1
|
Milkovich SK, Buguis FL, Boyle PD, Gilroy JB. Pnictogen-Rich Heterocycles Derived from a Phosphadiazonium Cation. Chemistry 2024; 30:e202400569. [PMID: 38393539 DOI: 10.1002/chem.202400569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 02/25/2024]
Abstract
Heterocycles that pair main group elements and nitrogen are extremely important within the π-conjugated heterocycles research community. Compared to the vast number of boron-nitrogen heterocycles, those that include phosphorus are less common. Furthermore, the use of phosphorus-nitrogen triple bonds of any type to prepare such compounds is unprecedented. Here, we pair pyridyl hydrazonide ligands with phosphadiazonium cations and demonstrate that the chelated Mes*NP group is directly implicated in the photophysical and redox properties observed for the resulting heterocycles. In doing so, we introduce a novel building block for the production of phosphorus-containing heterocycles that could find use in small molecule activation and catalysis or as the functional component of emerging organic electronics.
Collapse
Affiliation(s)
- Shaun K Milkovich
- Department of Chemistry, The University of Western Ontario (Western University), 1151 Richmond St. N., London, ON, N6A 5B7, Canada
| | - Francis L Buguis
- Department of Chemistry, The University of Western Ontario (Western University), 1151 Richmond St. N., London, ON, N6A 5B7, Canada
| | - Paul D Boyle
- Department of Chemistry, The University of Western Ontario (Western University), 1151 Richmond St. N., London, ON, N6A 5B7, Canada
| | - Joe B Gilroy
- Department of Chemistry, The University of Western Ontario (Western University), 1151 Richmond St. N., London, ON, N6A 5B7, Canada
| |
Collapse
|
2
|
LaPierre EA, Patrick BO, Manners I. Synthesis of Carbene-Stabilized PNPN Fragments and Their Carbene-Dependent Redox Properties. J Am Chem Soc 2024; 146:6326-6335. [PMID: 38408316 DOI: 10.1021/jacs.4c00148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Herein, we report the synthesis of carbene-stabilized 1,3-diaza-2,4-diphosphabutenes CAACMePNPNCAACMe 4CAAC (CAACMe = 1-[2,6-bis(isopropyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene) and IPrPNPNIPr 4NHC (IPr = 1,3-Bis(2,6-diisopropylphenyl)-imidazol-2-ylidene). The bonding in both systems is defined by a delocalized polar covalent π-system, with 4NHC exhibiting increased conjugation relative to 4CAAC. The nature of the stabilizing carbene also influences the redox properties of the compound, with 4CAAC undergoing potassium-mediated reduction to the closed-shell P-P bonded dimer K252, which upon treatment with Kryptofix-2,2,2 converts to the transient radical anion [Kcrypt][5], the formal one-electron reduction product of 4CAAC. In contrast, 4NHC undergoes reversible one-electron oxidation to the stable radical cation [6NHC][SbF6]. Computational and spectroscopic analyses of both radical species are suggestive of unevenly delocalized spin, with the bulk of the spin density residing on phosphorus in both cases.
Collapse
Affiliation(s)
- Etienne A LaPierre
- Department of Chemistry, University of Victoria, 3800 Finnerty Rd, Victoria, British Columbia V8P 5C2, Canada
| | - Brian O Patrick
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Ian Manners
- Department of Chemistry, University of Victoria, 3800 Finnerty Rd, Victoria, British Columbia V8P 5C2, Canada
| |
Collapse
|
3
|
Zhong Q, Mardyukov A, Solel E, Ebeling D, Schirmeisen A, Schreiner PR. On-Surface Synthesis and Real-Space Visualization of Aromatic P 3 N 3. Angew Chem Int Ed Engl 2023; 62:e202310121. [PMID: 37702299 DOI: 10.1002/anie.202310121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 09/11/2023] [Accepted: 09/12/2023] [Indexed: 09/14/2023]
Abstract
On-surface synthesis is at the verge of emerging as the method of choice for the generation and visualization of unstable or unconventional molecules, which could not be obtained via traditional synthetic methods. A case in point is the on-surface synthesis of the structurally elusive cyclotriphosphazene (P3 N3 ), an inorganic aromatic analogue of benzene. Here, we report the preparation of this fleetingly existing species on Cu(111) and Au(111) surfaces at 5.2 K through molecular manipulation with unprecedented precision, i.e., voltage pulse-induced sextuple dechlorination of an ultra-small (about 6 Å) hexachlorophosphazene P3 N3 Cl6 precursor by the tip of a scanning probe microscope. Real-space atomic-level imaging of cyclotriphosphazene reveals its planar D3h -symmetric ring structure. Furthermore, this demasking strategy has been expanded to generate cyclotriphosphazene from a hexaazide precursor P3 N21 via a different stimulation method (photolysis) for complementary measurements by matrix isolation infrared and ultraviolet spectroscopy.
Collapse
Affiliation(s)
- Qigang Zhong
- Institute of Applied Physics, Justus Liebig University Giessen, Giessen, Germany
- Center for Materials Research (ZfM), Justus Liebig University Giessen, Giessen, Germany
| | - Artur Mardyukov
- Center for Materials Research (ZfM), Justus Liebig University Giessen, Giessen, Germany
- Institute of Organic Chemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Ephrath Solel
- Center for Materials Research (ZfM), Justus Liebig University Giessen, Giessen, Germany
- Institute of Organic Chemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Daniel Ebeling
- Institute of Applied Physics, Justus Liebig University Giessen, Giessen, Germany
- Center for Materials Research (ZfM), Justus Liebig University Giessen, Giessen, Germany
| | - André Schirmeisen
- Institute of Applied Physics, Justus Liebig University Giessen, Giessen, Germany
- Center for Materials Research (ZfM), Justus Liebig University Giessen, Giessen, Germany
| | - Peter R Schreiner
- Center for Materials Research (ZfM), Justus Liebig University Giessen, Giessen, Germany
- Institute of Organic Chemistry, Justus Liebig University Giessen, Giessen, Germany
| |
Collapse
|
4
|
Zhu B, Song Y, Zhu J, Rauhut G, Jiang J, Zeng X. FP(μ-N) 2 S: A Sulfur-Pnictogen Four-Membered Ring with 6π Electrons. Chemistry 2023; 29:e202300251. [PMID: 37261435 DOI: 10.1002/chem.202300251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/28/2023] [Accepted: 06/01/2023] [Indexed: 06/02/2023]
Abstract
The new 6π-electron four-membered ring compound 3-fluoro-1λ2 ,2,4,3λ3 -thiadiazaphosphetidine, FP(μ-N)2 S, has been generated in the gas phase through high-vacuum flash pyrolysis (HVFP) of thiophosphoryl diazide, FP(S)(N3 )2 , at 1000 K. Subsequent isolation of FP(μ-N)2 S in cryogenic matrices (Ar, Ne, and N2 ) allows its characterization with matrix-isolation IR and UV-vis spectroscopy by combination with 15 N-isotope labeling and computations at the CCSD(T)-F12a/VTZ-F12 level of theory. Upon visible-light irradiation at 550 nm, this cyclic compound undergoes ring-opening to the thiazyl isomer FPNSN, followed by dissociation to FP and SN2 under subsequent UV-irradiation at 365 nm. In sharp contrast to the square planar structure for the isolobal four-membered ring S2 N2 , a puckered structure with significant biradical character has been found for FP(μ-N)2 S.
Collapse
Affiliation(s)
- Bifeng Zhu
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China
| | - Yanlin Song
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Jun Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany
| | - Junjie Jiang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China
| | - Xiaoqing Zeng
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China
| |
Collapse
|
5
|
Abstract
The occurrence of aromaticity in organic molecules is widely accepted, but its occurrence in purely metallic systems is less widespread. Molecules comprising only metal atoms (M) are known to be able to exhibit aromatic behaviour, sustaining ring currents inside an external magnetic field along M-M connection axes (σ-aromaticity) or above and below the plane (π-aromaticity) for cyclic or cage-type compounds. However, all-metal compounds provide an extension of the electrons' mobility also in other directions. Here, we show that regular {Bi6} prisms exhibit a non-localizable molecular orbital of f-type symmetry and generate a strong ring current that leads to a behaviour referred to as φ-aromaticity. The experimentally observed heterometallic cluster [{CpRu}3Bi6]-, based on a regular prismatic {Bi6} unit, displays aromatic behaviour; according to quantum chemical calculations, the corresponding hypothetical Bi62- prism shows a similar behaviour. By contrast, [{(cod)Ir}3Bi6] features a distorted Bi6 moiety that inhibits φ-aromaticity.
Collapse
|
6
|
Frenette BL, Trach J, Ferguson MJ, Rivard E. Frustrated Lewis Pair Adduct of Atomic P(-1) as a Source of Phosphinidenes (PR), Diphosphorus (P 2 ), and Indium Phosphide. Angew Chem Int Ed Engl 2023; 62:e202218587. [PMID: 36625676 DOI: 10.1002/anie.202218587] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/11/2023]
Abstract
We report phosphinidenes (PR) stabilized by an intramolecular frustrated Lewis pair (FLP) chelate. These adducts include the parent phosphinidene, PH, which is accessed via thermolysis of coordinated HPCO. The reported FLP-PH species acts as a springboard to other phosphorus-containing compounds, such as FLP-adducts of diphosphorus (P2 ) and InP3 . Our new adducts participate in thermal- or light-induced phosphinidene elimination (of both PH and PR, R=organic group), transfer P2 units to an organic substrate, and yield the useful semiconductor InP at only 110 °C from solution.
Collapse
Affiliation(s)
- Brandon L Frenette
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada
| | - Jonathan Trach
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada
| | - Michael J Ferguson
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada
| |
Collapse
|
7
|
Srikanth K, Kumar A, Tammineni RR. Unraveling the Photoelectron Spectrum of 1-Phospha-2,3,4-triazolate Anion, HCPN 3-, A Theoretical Approach. J Phys Chem A 2023; 127:78-91. [PMID: 36563286 DOI: 10.1021/acs.jpca.2c06701] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The first five low-lying electronic states of HCPN3 are probed through extensive ab initio electronic structure and quantum dynamics studies to reproduce the 193 nm photoelectron spectrum. Vibronic Hamiltonian is constructed and availed for time-dependent (TD) and time-independent (TI) quantum dynamical studies. The presence of numerous conical intersections (CIs) and crossings among electronic states yielded interesting nonadiabatic effects in the photoelectron bands of the overall spectrum. Moreover, the theoretical bands corresponding to five electronic states have reproduced all three experimental spectral bands. Among these, the first two bands originated due to a combination of four electronic states as predicted by previous studies. The third band corresponds to the fifth electronic state. The results calculated via TD and TI approaches exhibited satisfying agreement with the experimental results.
Collapse
Affiliation(s)
- Korutla Srikanth
- Department of Chemistry, Indian Institute of Technology Patna, Patna801106, India
| | - Abhishek Kumar
- Department of Chemistry, Indian Institute of Technology Patna, Patna801106, India
| | | |
Collapse
|
8
|
Petrov A, Conrad L, Coles NT, Weber M, Andrae D, Zagidullin A, Miluykov V, Müller C. Reactivity of Sodium Pentaphospholide Na[
cyclo
‐P
5
] towards C≡E (E=C, N, P) Triple Bonds. Chemistry 2022; 28:e202203056. [PMID: 36210344 PMCID: PMC10098531 DOI: 10.1002/chem.202203056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Indexed: 11/16/2022]
Abstract
A diglyme solution of Na[cyclo-P5 ] (1) reacts with alkynes and isolobal nitriles and phosphaalkynes to afford the otherwise elusive (aza)phospholide anions 2 a-c, 4 a,b, and 6. The reaction of Na[cyclo-P5 ] with alkynes and nitriles was studied by means of DFT methods, which suggested a concerted mechanism for the formation of 2 a and 4 b. The anions 2 a-c, 4 a,b, and 6 coordinate in an η5 -fashion towards FeII to give the sandwich (aza)phosphametallocenes 3 a-c, 5 a,b and 7 in moderate to good yields. The new compounds were characterized by means of multinuclear NMR spectroscopy, single-crystal X-ray diffraction and cyclic voltammetry.
Collapse
Affiliation(s)
- Andrey Petrov
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstr. 34/36 14195 Berlin Germany
| | - Lawrence Conrad
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Nathan T. Coles
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstr. 34/36 14195 Berlin Germany
- School of Chemistry University of Nottingham University Park Nottingham NG7 2RD United Kingdom
| | - Manuela Weber
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstr. 34/36 14195 Berlin Germany
| | - Dirk Andrae
- Institute of Chemistry and Biochemistry Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Almaz Zagidullin
- Arbuzov Institute of Organic and Physical Chemistry FRC Kazan Scientific Center of RAS Arbuzov Str. 8 Kazan Russia
| | - Vasili Miluykov
- Arbuzov Institute of Organic and Physical Chemistry FRC Kazan Scientific Center of RAS Arbuzov Str. 8 Kazan Russia
| | - Christian Müller
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstr. 34/36 14195 Berlin Germany
| |
Collapse
|
9
|
Kysliak O, Schreiner SHF, Grabicki N, Liebing P, Weigend F, Dumele O, Kretschmer R. A Planar Five‐Membered Aromatic Ring Stabilized by Only Two π‐Electrons. Angew Chem Int Ed Engl 2022; 61:e202206963. [PMID: 35593009 PMCID: PMC9401857 DOI: 10.1002/anie.202206963] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Indexed: 11/10/2022]
Abstract
Many chemicals known today are partially or fully aromatic, since a ring framework experiences additional stabilization through the delocalization of π‐electrons. While aromatic rings with equal numbers of π‐electrons and ring atoms such as benzene are particularly stable, those with the minimally required two π‐electrons are very rare and yet remain limited to three‐ and four‐membered rings if not stabilized in the coordination sphere of heavy metals. Here we report the facile synthesis of a dipotassium cyclopentagallene, a unique example of a five‐membered aromatic ring stabilized by only two π‐electrons. Single‐crystal X‐ray diffraction revealed a planar Ga5 ring with almost equal gallium–gallium bond lengths, which together with computational and spectroscopic data confirm its aromatic character. Our results prove that aromatic stabilization goes far beyond what has previously been assumed as minimum π‐electron count in a five‐atom ring fragment.
Collapse
Affiliation(s)
- Oleksandr Kysliak
- Institute of Inorganic and Analytical Chemistry (IAAC) Friedrich Schiller University Jena Humboldtstraße 8 07743 Jena Germany
| | - Simon H. F. Schreiner
- Institute of Inorganic and Analytical Chemistry (IAAC) Friedrich Schiller University Jena Humboldtstraße 8 07743 Jena Germany
- Institute of Chemistry University of Technology Chemnitz Straße der Nationen 62 09111 Chemnitz Germany
| | - Niklas Grabicki
- Department of Chemistry & IRIS Adlershof Humboldt University Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - Phil Liebing
- Institute of Inorganic and Analytical Chemistry (IAAC) Friedrich Schiller University Jena Humboldtstraße 8 07743 Jena Germany
| | - Florian Weigend
- Department of Chemistry Philipps-Universität Marburg Hans-Meerwein-Str. 4 35043 Marburg Germany
| | - Oliver Dumele
- Department of Chemistry & IRIS Adlershof Humboldt University Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - Robert Kretschmer
- Institute of Inorganic and Analytical Chemistry (IAAC) Friedrich Schiller University Jena Humboldtstraße 8 07743 Jena Germany
- Institute of Chemistry University of Technology Chemnitz Straße der Nationen 62 09111 Chemnitz Germany
- Jena Center for Soft Matter (JCSM) Friedrich Schiller University Jena Philosophenweg 7 07743 Jena Germany
| |
Collapse
|
10
|
Zhang C, Zhu C, Eckhardt AK, Kaiser RI. Formation of the elusive tetrahedral P 3N molecule. SCIENCE ADVANCES 2022; 8:eabo5792. [PMID: 35648866 PMCID: PMC9159698 DOI: 10.1126/sciadv.abo5792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
The tetrahedral 1,2,3-triphospha-4-azatricyclo [1.1.0.02,4] butane (P3N) molecule-an isovalent species of phosphorus (P4)-was prepared in low-temperature (5 K) phosphine-nitrogen ices and was identified in the gas phase through isomer-selective, tunable, soft photoionization reflectron time-of-flight mass spectrometry. Theoretical calculations reveal that the substitution of a single phosphorus atom by nitrogen in the P4 molecule results in enhanced spherical aromaticity while simultaneously increasing the strain energy from 74 to 195 kJ mol-1. In P3N, the P─P bond is shortened compared to those in P4 by 3.6 pm, while the P─N─P bond angle of 73.0° is larger by 13.0° compared to the P─P─P bond angle of 60.0° in P4. The identification of tetrahedral P3N enhances our fundamental understanding of the chemical bonding, electronic structure, and stability of binary, interpnictide tetrahedral molecules and reveals a universal route to prepare ring strained cage molecules in extreme environments.
Collapse
Affiliation(s)
- Chaojiang Zhang
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Cheng Zhu
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - André K. Eckhardt
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| |
Collapse
|
11
|
Kysliak O, Schreiner SHF, Grabicki N, Liebing P, Weigend F, Dumele O, Kretschmer R. A Planar Five‐Membered Aromatic Ring Stabilized by Only Two π‐Electrons. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Oleksandr Kysliak
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena IAAC GERMANY
| | - Simon H. F. Schreiner
- Chemnitz University of Technology: Technische Universitat Chemnitz Institut für Chemie GERMANY
| | - Niklas Grabicki
- Humboldt-Universität zu Berlin: Humboldt-Universitat zu Berlin Department of Chemistry GERMANY
| | - Phil Liebing
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena IAAC GERMANY
| | - Florian Weigend
- Philipps-Universität Marburg: Philipps-Universitat Marburg Department of Chemistry, GERMANY
| | - Oliver Dumele
- Humboldt-Universität zu Berlin: Humboldt-Universitat zu Berlin Department of chemistry GERMANY
| | - Robert Kretschmer
- Chemnitz University of Technology: Technische Universitat Chemnitz Institut für Chemie Straße der Nationen 62 09111 Chemnitz GERMANY
| |
Collapse
|
12
|
|
13
|
Eckhardt AK, Riu MLY, Müller P, Cummins CC. Staudinger Reactivity and Click Chemistry of Anthracene ( A)-Based Azidophosphine N 3P A. Inorg Chem 2022; 61:1270-1274. [PMID: 35020379 DOI: 10.1021/acs.inorgchem.1c03753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
11-Azido-9,10-dihydro-9,10-phosphanoanthracene (N3PA) has been demonstrated recently as a transfer reagent for molecular phosphorus mononitride (PN) because it easily dissociates at room temperature into dinitrogen (N2), PN, and anthracene (A). Here we report further reactivity studies of the N3PA molecule including strain-promoted 1,3-dipolar cycloaddition with cyclooctyne and Staudinger-type reactivity. Calculations at the DLPNO-CCSD(T)/cc-pVTZ//PBE0-D3(BJ)/cc-pVTZ level of theory indicate that the click reaction is faster than the dissociation of N3PA. The Staudinger-type reactivity enabled transfer of the NPA fragment to a base-stabilized silylene. The previously reported intermediate of vanadium trisanilide with an NPA ligand could be isolated in 61% yield and structurally characterized in a single-crystal X-ray diffraction experiment. In line with the previously reported phosphinidene reactivity of the transient vanadium phosphorus mononitride complex, thermolysis or irradiation of the complex leads to A elimination and formation of the corresponding vanadium PN dimer or trimer, respectively.
Collapse
Affiliation(s)
- André K Eckhardt
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Martin-Louis Y Riu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peter Müller
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Christopher C Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
14
|
Zhu B, Jiang J, Lu B, Li X, Jiang X, Rauhut G, Zeng X. Phosphenic isocyanate (O2PNCO): Gas-phase generation, characterization, and photodecomposition reactions. Chem Commun (Camb) 2022; 58:10703-10706. [DOI: 10.1039/d2cc03178g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phosphenic isocyanate (O2PNCO), a novel phosphorus-containing small molecule has been generated by thermolysis of a dioxaphospholane-based precursor. The characterization of O2PNCO with IR and UV-vis spectroscopy in solid N2 and...
Collapse
|
15
|
Gu X, Yang L, Jin P. Planar Inorganic Five-Membered Heterocycles with σ+π Dual Aromaticity in Both S0 and T1 States. Phys Chem Chem Phys 2022; 24:22091-22101. [DOI: 10.1039/d2cp03116g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclic species being aromatic in both the lowest singlet and triplet electronic states (so-called adaptive aromaticity) are scarce. To date, the reported systems are mostly organometallic heterocycles with the aromaticities...
Collapse
|
16
|
Tkachenko NV, Popov IA, Kulichenko M, Fedik N, Sun Z, Muñoz‐Castro A, Boldyrev AI. Bridging Aromatic/Antiaromatic Units: Recent Advances in Aromaticity and Antiaromaticity in Main‐Group and Transition‐Metal Clusters from Bonding and Magnetic Analyses. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Nikolay V. Tkachenko
- Department of Chemistry and Biochemistry Utah State University 0300 Old Main Hill 84322-0300 Logan UT USA
| | - Ivan A. Popov
- Theoretical Division Los Alamos National Laboratory 87545 Los Alamos NM USA
| | - Maksim Kulichenko
- Department of Chemistry and Biochemistry Utah State University 0300 Old Main Hill 84322-0300 Logan UT USA
| | - Nikita Fedik
- Department of Chemistry and Biochemistry Utah State University 0300 Old Main Hill 84322-0300 Logan UT USA
| | - Zhong‐Ming Sun
- Tianjin Key Lab of Rare Earth Materials and Applications State Key Laboratory of Elemento-Organic Chemistry School of Materials Science and Engineering Nankai University 300350 Tianjin China
| | - Alvaro Muñoz‐Castro
- Grupo de Química Inorgánica y Materiales Moleculares Facultad de Ingeniería Universidad Autonoma de Chile El Llano Subercaseaux 2801 Santiago Chile
| | - Alexander I. Boldyrev
- Department of Chemistry and Biochemistry Utah State University 0300 Old Main Hill 84322-0300 Logan UT USA
| |
Collapse
|
17
|
Yu Q, Zhang L, He Y, Pan J, Li H, Bian GQ, Chen X, Tan G. A stable tetrazagallole and its radical anion dimer. Chem Commun (Camb) 2021; 57:9268-9271. [PMID: 34519308 DOI: 10.1039/d1cc03448k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The reaction of the carbazole ligand supported Ga(I) compound LGa(THF) (3) and 1-azido-4-(tert-butyl)benzene (ArN3) afforded the first stable tetrazagallole LGaN4Ar2 (4) bearing a three-coordinate Ga atom. Reduction of 4 with elemental potassium resulted in the radical dimer {[K(18-c-6)]+[4]˙-}2, featuring a strong antiferromagnetic interaction between the spin centers.
Collapse
Affiliation(s)
- Qian Yu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Li Zhang
- Center of Materials Science and Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China
| | - Yuhao He
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Jinjing Pan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Hao Li
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Guo-Qing Bian
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| | - Xiaodan Chen
- College of Chemistry and Material, Jinan University, Guangzhou 510632, China
| | - Gengwen Tan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
| |
Collapse
|
18
|
Ota K, Kinjo R. Heavier element-containing aromatics of [4 n+2]-electron systems. Chem Soc Rev 2021; 50:10594-10673. [PMID: 34369490 DOI: 10.1039/d0cs01354d] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
While the implication of the aromaticity concept has been dramatically expanded to date since its emergence in 1865, the classical [4n+2]/4n-electron counting protocol still plays an essential role in evaluating the aromatic nature of compounds. Over the last few decades, a variety of heavier heterocycles featuring the formal [4n+2] π-electron arrangements have been developed, which allows for assessing their aromatic nature. In this review, we present recent developments of the [4n+2]-electron systems of heavier heterocycles involving group 13-15 elements. The synthesis, spectroscopic data, structural parameters, computational data, and reactivity are introduced.
Collapse
Affiliation(s)
- Kei Ota
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Nanyang Link 21, Singapore 637371, Singapore
| | - Rei Kinjo
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Nanyang Link 21, Singapore 637371, Singapore
| |
Collapse
|
19
|
Abstract
Recently, we discovered that the delocalization of nitrogen lone-pair electrons (NLPEs) in five-membered nitrogen heterocycles created a second σ-aromaticity in addition to the prototypical π-aromaticity. Such dual-aromatic compounds, such as the pentazole anion, were proved to have distinct chemistry in comparison to traditional π-aromatics, such as benzene, and were surprisingly unstable, susceptible to electrophilic attack, and relatively difficult to obtain. The dual-aromatics are basic in nature, but prefer not to be protonated when confronting more than three hydronium/ammonium ions, which violates common sense understanding of acid−base neutralization for a reason that is unclear. Here, we carried out 63 test simulations to explore the stability and reactivity of three basic heterocycle anions (pentazole anion N5¯, tetrazole anion N4C1H1¯, and 1,2,4-triazole anion N3C2H2¯) in four types of solvents (acidic ions, H3O+ and NH4+, polar organics, THF, and neutral organics, benzene) with different acidities and concentrations. By quantum mechanical calculations of the electron density, atomistic structure, interatomic interactions, molecular orbital, magnetic shielding, and energetics, we confirmed the presence of dual aromaticity in the heterocyclic anions, and discovered their reactivity to be a competition between their basicity and dual aromaticity. Interestingly, when the acidic ions H3O+/NH4+ are three times more in number than the basic heterocyclic anions, the anions turn to violate acid−base neutralization and remain unprotonated, and the surrounding acidic ions start to show a significant stabilization effect on the studied heterocyclic anions. This work brings new knowledge to nitrogen aromatics and the finding is expected to be adaptable for other pnictogen five-membered ring systems.
Collapse
|
20
|
Riu MLY, Transue WJ, Rall JM, Cummins CC. An Azophosphine Synthetic Equivalent of Mesitylphosphaazide and Its 1,3-Dipolar Cycloaddition Reactions. J Am Chem Soc 2021; 143:7635-7640. [PMID: 33999612 DOI: 10.1021/jacs.1c03333] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dibenzo-7-phosphanorbornadiene-substituted diazene MesN2PA (1, where Mes = mesityl, A = anthracene, or C14H10), a synthetic equivalent of mesitylphosphaazide (MesN2P) and anthracene, was synthesized by treatment of [Ph3BPA][Na(OEt2)2] with [MesN2]OTf (OTf = CF3SO3-) in thawing tetrahydrofuran (14% isolated yield). Treatment of 1 with unsaturated molecules cyclooctyne, [Na(dioxane)2.5][OCP] (phosphaethynolate), and Ad-C≡P (Ad = adamantyl) results in the corresponding [3 + 2] phosphaazide-(phospha)alkyne cycloadducts, with concomitant loss of anthracene in 65%, 49%, and 38% isolated yield, respectively. Structural data for the phosphaethynolate cycloadduct ([3][Na(12-crown-4)2]) were obtained in a single-crystal X-ray diffraction study. A diazatriphosphole was generated by combining 1 with P2A2, a thermally activated anthracene-based molecular precursor to diphosphorus (P2). Thermolysis (33-65 °C) of 1 in benzene-d6 leads to anthracene extrusion. This process has a unimolecular kinetic profile and proceeds with activation parameters of ΔH⧧ = 21.6 ± 0.3 kcal/mol and ΔS⧧= -4.9 ± 0.8 cal/(mol K).
Collapse
Affiliation(s)
- Martin-Louis Y Riu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wesley J Transue
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jan M Rall
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Christopher C Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
21
|
Hu Z, Guo W. Fibrous Phase Red Phosphorene as a New Photocatalyst for Carbon Dioxide Reduction and Hydrogen Evolution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2008004. [PMID: 33792191 DOI: 10.1002/smll.202008004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/08/2021] [Indexed: 06/12/2023]
Abstract
2D photocatalysts are one of the hottest issues in energy and material science. In the field of photocatalysis, a 2D material with an appropriate bandgap of 1.3 to 2.0 eV is desirable. Herein, a new kind of fibrous phase red phosphorene with a bandgap between 1.43 to 1.54 eV is obtained. This is much better than black phosphorus because the bandgap of black P depends of its layer number. The black P needs to be as thin as 1-2 layers for suitable band diagram, which is difficult to control. The fibrous red phosphorene is first used for photocatalytic CO2 reduction, and its activity is superior to the majority of mainstream photocatalysts and reaches a record-high value among phosphorus. Besides, its activity in hydrogen evolution is higher than most of the phosphorus photocatalysts. The intralayer charge transfer is much easier than interlayer transfer. The mobility of electron and hole along the phosphorene plane is about 20 times higher than that perpendicular to different layers. The activity sites is at region between the two P[21] chains. These regions are easy to be exposed for fibrous phase phosphorene, making it to exhibit high activity.
Collapse
Affiliation(s)
- Zhuofeng Hu
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, China
| | - Weiqing Guo
- School of Environmental and Chemical Engineering, Foshan University, Foshan, 528000, China
| |
Collapse
|
22
|
Du J, Hunger D, Seed JA, Cryer JD, King DM, Wooles AJ, van Slageren J, Liddle ST. Dipnictogen f-Element Chemistry: A Diphosphorus Uranium Complex. J Am Chem Soc 2021; 143:5343-5348. [PMID: 33792307 DOI: 10.1021/jacs.1c02482] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The first isolation and structural characterization of an f-element dinitrogen complex was reported in 1988, but an f-element complex with the first heavier group 15 homologue diphosphorus has to date remained unknown. Here, we report the synthesis of a side-on bound diphosphorus complex of uranium(IV) using a 7λ3-(dimethylamino)phosphadibenzonorbornadiene-mediated P atom transfer approach. Experimental and computational characterization reveals that the diphosphorus ligand is activated to its dianionic (P2)2- form and that in-plane U-P π-bonding dominates the bonding of the U(μ-η2:η2-P2)U unit, which is supplemented by a weak U-P interaction of δ symmetry. A preliminary reactivity study demonstrates conversion of this diphosphorus complex to unprecedented uranium cyclo-P3 complexes, suggesting in situ generation of transient, reactive phosphido species.
Collapse
Affiliation(s)
- Jingzhen Du
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - David Hunger
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - John A Seed
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Jonathan D Cryer
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - David M King
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, U.K
| | - Ashley J Wooles
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | - Joris van Slageren
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Stephen T Liddle
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| |
Collapse
|
23
|
A tris-spiro metalla-aromatic system featuring Craig-Möbius aromaticity. Nat Commun 2021; 12:1319. [PMID: 33637738 PMCID: PMC7910433 DOI: 10.1038/s41467-021-21648-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/05/2021] [Indexed: 12/03/2022] Open
Abstract
As aromaticity is one of the most fundamental concepts in chemistry, the construction of aromatic systems has long been an important subject. Herein, we report the synthesis and characterization of a tris-spiroaromatic complex, hexalithio spiro vanadacycle 2. The delocalization of the four electrons within the two V 3d orbitals and the π* orbitals of the three biphenyl ligands leads to a 40π Craig-Möbius aromatic system with three metalla-aromatic rings, as revealed by both experimental measurements and theoretical analyses. For comparison, if Cr is used instead of V, a similar Craig-Möbius aromatic system can not be generated. In this case, pentalithio spiro chromacycle 3 is obtained, and the Cr center uses its two 3d orbitals to form two independent metalla-aromatic rings. This work presents a type of aromatic systems that will contribute to both aromaticity theory and organometallic chemistry. Spiroaromatic compounds are advantageous platforms for designing expanded aromatic systems. Herein, the authors present a tris‐spiro metalla‐aromatic Vanadium compound which forms a 40π Craig‐Möbius aromatic system.
Collapse
|
24
|
Rottschäfer D, Neumann B, Stammler H, Sergeieva T, Andrada DM, Ghadwal RS. Isolation of a 16π-Electrons 1,4-Diphosphinine-1,4-diide with a Planar C 4 P 2 Ring. Chemistry 2021; 27:3055-3064. [PMID: 33080114 PMCID: PMC7898681 DOI: 10.1002/chem.202003617] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/05/2020] [Indexed: 02/02/2023]
Abstract
Herein, we report the first 1,4-diphosphinine-1,4-diide compound [(ADCPh )P]2 (5-Ph) (ADCPh =PhC{(NDipp)C}2 ; Dipp=2,6-iPr2 C6 H3 ) derived from an anionic dicarbene (ADCPh ) as a red crystalline solid. Compound 5-Ph containing a 16π-electron planar fused-tricyclic ring system was obtained by the 4e reduction of [(ADCPh )PCl2 ]2 (4-Ph) with Mg (or KC8 ) in a quantitative yield. Experimental and computational results imply that the central 8π-electrons C4 P2 ring of 5-Ph, which is fused between two 6π-electrons C3 N2 aromatic rings, is antiaromatic. Thus, each of the phosphorus atoms of 5-Ph has two electron-lone-pairs, one in a p-type orbital is in conjugation with the C=C bonds of the C4 P2 ring, while the second resides in a σ-symmetric orbital. This can be shown with the gold complex [(ADCPh )P(AuCl)2 ]2 (6-Ph) obtained by reacting 5-Ph with (Me2 S)AuCl. A mixture of 5-Ph and 4-Ph undergoes comproportionation in the presence of MgCl2 to form the intermediate oxidation state compound [(ADCAr )P]2 (MgCl4 ) (7-Ph), which is an aromatic species.
Collapse
Affiliation(s)
- Dennis Rottschäfer
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Beate Neumann
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Tetiana Sergeieva
- Inorganic and Computational Chemistry GroupAllgemeine und Anorganische ChemieUniversität des SaarlandesCampus C4.166123SaarbrückenGermany
| | - Diego M. Andrada
- Inorganic and Computational Chemistry GroupAllgemeine und Anorganische ChemieUniversität des SaarlandesCampus C4.166123SaarbrückenGermany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| |
Collapse
|
25
|
Patra SG, Mondal T. Interplay of Hückel and Möbius Aromaticity in Metal-Metal Quintuple Bonded Complexes of Cr, Mo, and W with Amidinate Ligand: Ab initio DFT and Multireference Analysis*. Chemphyschem 2021; 22:298-311. [PMID: 33252161 DOI: 10.1002/cphc.202000923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 11/29/2020] [Indexed: 11/10/2022]
Abstract
The aromaticity of metal-metal quintuple bonded complexes of the type M2 L2 (M=Cr, Mo, and W; L=amidinate) are studied employing gauge including magnetically induced ring current (GIMIC) analysis and electron density of delocalized bonds (EDDB). It is found that the complexes possess two types of aromaticity: i) Hückel aromaticity through delocalization of ligand π electrons with metal-metal δ-bond-forming 6 conjugated electrons (4π and 2δ) ring; ii) Craig-Möbius aromaticity through delocalization of π electrons of both the ligands with metal d-orbitals in Craig type orientation forming 10π electrons ring with a double twist. Extended transition state natural orbital chemical valence (ETS-NOCV) and canonical molecular orbital natural chemical shielding (CMO-NCS) analysis confirm the Craig-Möbius type arrangement of the orbitals. Furthermore, the unprecedented Hückel and Möbius type aromaticity is confirmed from the plot of the current pathways using 3D line integral convolution (3D-LIC) plots. The metal-metal bond order also increases down the group as justified from the complete active space self-consistent field (CASSCF) analysis. Due to an increase in the π and δ electron conjugation, both the Hückel and Möbius aromaticity increase down the group.
Collapse
Affiliation(s)
- Shanti G Patra
- Department of Chemical Sciences, Ariel University, Ariel, 40700, Israel
| | - Totan Mondal
- Department of Organic Chemistry and the, Lise Meitner-Minerva Centre for Computational Quantum Chemistry, The Hebrew University, Jerusalem, 91904, Israel
| |
Collapse
|
26
|
Eulenstein AR, Franzke YJ, Lichtenberger N, Wilson RJ, Deubner HL, Kraus F, Clérac R, Weigend F, Dehnen S. Substantial π-aromaticity in the anionic heavy-metal cluster [Th@Bi 12] 4. Nat Chem 2021; 13:149-155. [PMID: 33288891 DOI: 10.1038/s41557-020-00592-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 10/27/2020] [Indexed: 01/30/2023]
Abstract
The concept of aromaticity was originally defined as a property of unsaturated, cyclic planar organic molecules like benzene, which gain stability by the inherent delocalization of 4n + 2 π-electrons over the ring atoms. Since then, π-aromaticity has been observed for a large variety of organic and inorganic non-metal compounds, yet, for molecules consisting only of metal atoms, it has remained restricted to systems with three to five atoms. Here, we present the straightforward synthesis of a metal 12-ring that exhibits 2π-aromaticity and has a ring current much stronger than that of benzene (6π) and equivalent to that of porphine (26π), despite these organic molecules having (much) larger numbers of π-electrons. Highly reducing reaction conditions allowed access to the heterometallic anion [Th@Bi12]4-, with interstitial Th4+ stabilizing a Bi128- moiety. Our results show that it is possible to design and generate substantial π-aromaticity in large metal rings, and we hope that such π-aromatic heavy-metal cycles will eventually find use in cluster-based reactions.
Collapse
Affiliation(s)
- Armin R Eulenstein
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany.,Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg, Marburg, Germany
| | - Yannick J Franzke
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.,Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Niels Lichtenberger
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany.,Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg, Marburg, Germany
| | - Robert J Wilson
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany.,Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg, Marburg, Germany
| | - H Lars Deubner
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Florian Kraus
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Rodolphe Clérac
- Univ. Bordeaux, CNRS, Centre de Recherche Paul Pascal, Pessac, France
| | - Florian Weigend
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany.
| | - Stefanie Dehnen
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany. .,Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg, Marburg, Germany.
| |
Collapse
|
27
|
Tofan D, Velian A. Interstellar Chemistry in a Glovebox: Elusive Diatomic P≡N, Exposed. ACS CENTRAL SCIENCE 2020; 6:1485-1487. [PMID: 32999923 PMCID: PMC7517113 DOI: 10.1021/acscentsci.0c01148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Daniel Tofan
- Department of Chemistry, University
of Washington, Seattle, Washington 98195-0005, United States
| | - Alexandra Velian
- Department of Chemistry, University
of Washington, Seattle, Washington 98195-0005, United States
| |
Collapse
|
28
|
Bass TM, Carr CR, Sherbow TJ, Fettinger JC, Berben LA. Syntheses of Square Planar Gallium Complexes and a Proton NMR Correlation Probing Metalloaromaticity. Inorg Chem 2020; 59:13517-13523. [DOI: 10.1021/acs.inorgchem.0c01908] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas M. Bass
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Cody R. Carr
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Tobias J. Sherbow
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - James C. Fettinger
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Louise A. Berben
- Department of Chemistry, University of California, Davis, California 95616, United States
| |
Collapse
|
29
|
Zong HH, Yao C, Sun CQ, Zhang JG, Zhang L. Structure and Stability of Aromatic Nitrogen Heterocycles Used in the Field of Energetic Materials. Molecules 2020; 25:molecules25143232. [PMID: 32679862 PMCID: PMC7397173 DOI: 10.3390/molecules25143232] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 11/16/2022] Open
Abstract
Understanding the stabilization of nitrogen heterocycles is critical in the field of energetic materials and calls for innovative knowledge of nitrogen aromatics. Herewith, we report for the first time that nitrogen lone pair electron (NLPE) delocalization in five-membered nitrogen heterocycles creates a second σ-aromaticity in addition to the prototypical π-aromaticity. The NLPE delocalization and the attendant dual-aromaticity are enhanced as more carbon atoms in the ring are substituted by unsaturated nitrogen atoms. The presence of adjacent nitrogen atoms in the ring can enhance the aromaticity of the nitrogen heterocycles and improve in-crystal intermolecular binding strength but will decrease the firmness of the individual molecular architecture. Notably, such σ-aromaticity is not present in six-membered nitrogen heterocycles, probably due to the longer bonds and broader regions of their rings; therefore, six-membered heterocycles present overall lower aromaticity than five-membered heterocycles. This work brings new knowledge to nitrogen aromatics and is expected to inspire broad interest in the chemistry community.
Collapse
Affiliation(s)
- He-Hou Zong
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China;
- CAEP Software Center for High Performance Numerical Simulation, Beijing 100088, China
| | - Chuang Yao
- Key Laboratory of Extraordinary Bond Engineering and Advance Materials Technology (EBEAM) of Chongqing, School of Materials Science and Engineering, Yangtze Normal University, Chongqing 408100, China; (C.Y.); (C.Q.S.)
| | - Chang Q Sun
- Key Laboratory of Extraordinary Bond Engineering and Advance Materials Technology (EBEAM) of Chongqing, School of Materials Science and Engineering, Yangtze Normal University, Chongqing 408100, China; (C.Y.); (C.Q.S.)
| | - Jian-Guo Zhang
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
- Correspondence: (J.-G.Z.); (L.Z.); Tel.: +86-1068918091 (J.-G.Z.); +86-1061935621 (L.Z.); Fax: +86-1068918091 (J.-G.Z.); +86-1061935702 (L.Z.)
| | - Lei Zhang
- CAEP Software Center for High Performance Numerical Simulation, Beijing 100088, China
- Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
- Correspondence: (J.-G.Z.); (L.Z.); Tel.: +86-1068918091 (J.-G.Z.); +86-1061935621 (L.Z.); Fax: +86-1068918091 (J.-G.Z.); +86-1061935702 (L.Z.)
| |
Collapse
|
30
|
Zhu C, Eckhardt AK, Bergantini A, Singh SK, Schreiner PR, Kaiser RI. The elusive cyclotriphosphazene molecule and its Dewar benzene-type valence isomer (P 3N 3). SCIENCE ADVANCES 2020; 6:eaba6934. [PMID: 32832667 PMCID: PMC7439403 DOI: 10.1126/sciadv.aba6934] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 06/08/2020] [Indexed: 06/11/2023]
Abstract
Although the chemistry of phosphorus and nitrogen has fascinated chemists for more than 350 years, the Hückel aromatic cyclotriphosphazene (P3N3, 2) molecule-a key molecular building block in phosphorus chemistry-has remained elusive. Here, we report a facile, versatile pathway producing cyclotriphosphazene and its Dewar benzene-type isomer (P3N3, 5) in ammonia-phosphine ices at 5 K exposed to ionizing radiation. Both isomers were detected in the gas phase upon sublimation via photoionization reflectron time-of-flight mass spectrometry and discriminated via isomer-selective photochemistry. Our findings provide a fundamental framework to explore the preparation of inorganic, isovalent species of benzene (C6H6) by formally replacing the C─H moieties alternatingly through phosphorus and nitrogen atoms, thus advancing our perception of the chemical bonding of phosphorus systems.
Collapse
Affiliation(s)
- Cheng Zhu
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - André K. Eckhardt
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany and Center for Materials Research (LaMa), Justus Liebig University, Heinrich-Buff-Ring 16, 35392 Giessen, Germany
| | - Alexandre Bergantini
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Santosh K. Singh
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Peter R. Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany and Center for Materials Research (LaMa), Justus Liebig University, Heinrich-Buff-Ring 16, 35392 Giessen, Germany
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
- W. M. Keck Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| |
Collapse
|
31
|
Xia K, Yuan J, Zheng X, Liu C, Gao H, Wu Q, Sun J. Predictions on High-Power Trivalent Metal Pentazolate Salts. J Phys Chem Lett 2019; 10:6166-6173. [PMID: 31560550 DOI: 10.1021/acs.jpclett.9b02383] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
High-energy-density materials (HEDMs) have been intensively studied for their significance in fundamental sciences and practical applications. Here, using the molecular crystal structure search method based on first-principles calculations, we have predicted a series of metastable energetic trivalent metal pentazolate salts MN15 (M= Al, Ga, Sc, and Y). These compounds have high energy densities, with the highest nitrogen content among the studied nitrides so far. Pentazolate N5- molecules stack up face-to-face and form wave-like patterns in the C2221 and Cc symmetries. The strong covalent bonding and very weak noncovalent interactions with nonbonded overlaps coexist in these ionic-like structures. We find MN15 molecular structures are mechanically stable up to high temperature (∼1000 K) and ambient pressure. More importantly, these trivalent metal pentazolate salts have high detonation pressure (∼80 GPa) and velocity (∼12 km/s). Their detonation pressures exceeding that of TNT and HMX make them good candidates for high-brisance green energetic materials.
Collapse
Affiliation(s)
- Kang Xia
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Jianan Yuan
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Xianxu Zheng
- National Key Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics , China Academy of Engineering Physics , Mianyang 621900 , Sichuan , China
| | - Cong Liu
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Hao Gao
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Qiang Wu
- National Key Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics , China Academy of Engineering Physics , Mianyang 621900 , Sichuan , China
| | - Jian Sun
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| |
Collapse
|
32
|
Zhang L, Yao C, Yu Y, Wang X, Sun CQ, Chen J. Mechanism and Functionality of Pnictogen Dual Aromaticity in Pentazolate Crystals. Chemphyschem 2019; 20:2525-2530. [PMID: 31418994 DOI: 10.1002/cphc.201900674] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/12/2019] [Indexed: 11/11/2022]
Abstract
Our recent work (J. Phys. Chem. Lett. 2019, 10, 2378) reported the discovery of the abnormal pnictogen dual aromaticity (π and σ) in cyclo-N5 - , which makes the anion unstable in nature but confers enhanced stability in sufficiently acid solution. Herein, we present systematic quantum calculations on the structures, energetics and dynamics of the pentazolate salt and metal pentazolate hydrates, focusing on the mechanism and functionality of the pnictogen dual aromaticity in these crystals, which are verified by experiments. We find that owning a net charge of -e is crucial to the formation of the dual aromaticity and the stabilization of the cyclo-N5 - . The competition between the dual aromaticity and the proton affinity drives the cyclo-N5 - to be unreactive to acid and remain unprotonated in these crystals. We decompose the crystal packing effect into pure mechanical compression and interspecies nonbonding interactions, and figure out that the type and number of the adjacent counterions of the cyclo-N5 - anion, instead of the compression effect, accounts for the protonation state reversion in the vacuum and in the crystal. The current work supports our original conclusion (Science 2018, 359, eaas8953) and is expected to provide compelling evidence against the current debate on the cyclo-N5 - stability (Science 2018, 359, eaao3672; J. Phys. Chem. Lett. 2018, 9, 7137; J. Am. Chem. Soc. 2019, 141, 2984).
Collapse
Affiliation(s)
- Lei Zhang
- CAEP Software Center for High Performance Numerical Simulation, Beijing, 100088, China.,Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China
| | - Chuang Yao
- EBEAM, Yangtze Normal University, Chongqing, 408100, China
| | - Yi Yu
- CAEP Software Center for High Performance Numerical Simulation, Beijing, 100088, China
| | - Xing Wang
- CAEP Software Center for High Performance Numerical Simulation, Beijing, 100088, China
| | - Chang Q Sun
- EBEAM, Yangtze Normal University, Chongqing, 408100, China.,NOVITAS, Nanyang Technological University, 639798, Singapore
| | - Jun Chen
- Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China.,Center for Applied Physics and Technology, Peking University, Beijing, 100871, China
| |
Collapse
|
33
|
Ellis JE. The Chatt reaction: conventional routes to homoleptic arenemetalates of d-block elements. Dalton Trans 2019; 48:9538-9563. [PMID: 30724934 DOI: 10.1039/c8dt05029e] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Joseph Chatt was the first to discover in the early 1960s that previously unknown transition metal compounds were accessible and isolable via the reactions of alkali metal arene radical anions with transition metal precursors containing good leaving groups, such as weakly basic neutral or anionic ligands, especially halides. Later Peter Timms confirmed the importance of these early studies with the synthesis of several new bis(arene)metal(0) sandwich compounds by a variant of Chatt's route. Following a brief historical survey of alkali metal arene compounds, first examined in some detail by Wilhelm Schlenk, use of these reagents in the conventional syntheses of anionic homoleptic arene metal complexes of the d-block elements will be described. In several cases these species are quite useful because they function as storable "naked" atomic metal anion reagents, especially in their reactions with carbon monoxide and isocyanides. In view of Chatt's seminal contributions to an often unique route to organometallic and inorganic compounds, it is proposed that this valuable synthetic method be named the "Chatt reaction" in honor of a giant of chemistry.
Collapse
Affiliation(s)
- John E Ellis
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA.
| |
Collapse
|
34
|
Zhang L, Yao C, Yu Y, Jiang SL, Sun CQ, Chen J. Stabilization of the Dual-Aromatic cyclo-N 5- Anion by Acidic Entrapment. J Phys Chem Lett 2019; 10:2378-2385. [PMID: 31021641 DOI: 10.1021/acs.jpclett.9b01047] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pentazole anion, the best candidate for full-nitrogen energetic materials, can be isolated only from acidic solution for unclear reasons, which hinders the high-yield realization of a full-nitrogen substance with higher energy density. Herein, we report for the first time the discovery of the dual aromaticity (π and σ) of cyclo-N5-, which makes the anion unstable in nature but confers additional stability in acidic surroundings. In addition to the usual π-aromaticity, similar to that of the prototypical benzene, five lone pairs are delocalized in the equatorial plane of cyclo-N5-, forming additional σ-aromaticity. It is the compatible coexistence of the inter-lone-pair repulsion and inter-lone-pair attraction within the σ-aromatic system that makes the naked cyclo-N5- highly reactive to electrophiles and easily broken. Only in sufficiently acid solution can the cyclo-N5- become unsusceptible to the electrophilic attack and gain extra stability through the formation of hydrogen-bonded complex from surrounding electrophiles; otherwise, the cyclo-N5- cannot be productively isolated. The dual aromaticity discovered in cyclo-N5- is expected to be universal for pnictogen five-membered ring systems.
Collapse
Affiliation(s)
- Lei Zhang
- Software Center for High Performance Numerical Simulation , Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
- Laboratory of Computational Physics , Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Chuang Yao
- EBEAM , Yangtze Normal University , Chongqing 408100 , China
| | - Yi Yu
- Software Center for High Performance Numerical Simulation , Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Sheng-Li Jiang
- Software Center for High Performance Numerical Simulation , Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Chang Q Sun
- EBEAM , Yangtze Normal University , Chongqing 408100 , China
- NOVITAS , Nanyang Technological University , 639798 Singapore
| | - Jun Chen
- Laboratory of Computational Physics , Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
- Center for Applied Physics and Technology , Peking University , Beijing 100871 , China
| |
Collapse
|
35
|
Ying H, Gong M, Pi C. Generation and reactivity of neutral 1,3-benzazaphosphole and anionic 1,3-benzazaphospholide ytterbium(iii) complexes. Dalton Trans 2019; 48:2722-2729. [PMID: 30720828 DOI: 10.1039/c8dt04768e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Treatment of Cp3Ln (Ln = Yb, Y) with 5-R3-6-R1-2-R2-1H-1,3-benzazaphosphole (HBp) (HBp1 (1a): R1 = H, R2 = 2,4,6-Me3C6H2, R3 = Me; HBp2(1b): R1 = Me, R2 = C6H5, R3 = H; HBp3(1c): R1 = R3 = H, R2 = C6H5) at room temperature gives the crystalline 1 : 1 Lewis acid-base adducts [(η1(p)-HBp)LnCp3] (2a-d) [Ln = Yb: Bp = Bp1 (2a), Bp2 (2b), Bp3 (2c); Ln = Y: Bp2 (2d)] with Ln-P donor bonds in good yields. Heating 2a-c in toluene leads to the liberation of one molecule of CpH to afford the corresponding N-bonded complexes [Cp2YbBp] (Bp = Bp1 (3a), Bp2 (3b), Bp3 (3c)). Interestingly, the P atom of complexes 3a-c can also be further coordinated to another Lewis acid such as Cp3Yb and B(C6F5)3 to give the adducts [Cp2Yb(μ-η1(N):η2(C,C):η1(P)-Bp)YbCp3] (Bp = Bp1 (4a), Bp2 (4b), Bp3 (4c)) and [Cp2Yb(μ-η1(N):η2(C,C):η1(P)-Bp)B(C6F5)3] (Bp = Bp1 (5a), Bp2 (5b), Bp3 (5c)), respectively. The molecular structures of complexes 2a, 4b-4c and 5c are confirmed by X-ray diffraction analysis.
Collapse
Affiliation(s)
- Huacheng Ying
- School of Material and Chemical Engineering, Qianjiang College, Hangzhou Normal University, Xuelin Street 16, Hangzhou, Zhejiang Province 310036, China.
| | | | | |
Collapse
|
36
|
Abstract
This year marks the 350th anniversary of the discovery of phosphorus by the alchemist Hennig Brand. However, this element was not included in the p-block of the periodic table until more recently. 2019 also marks the 150th anniversary of the preliminary tabular arrangement of the elements into the periodic system by Mendeleev. Of the 63 elements known in 1869, almost one-third of them belonged to what ultimately became the p-block, and Mendeleev predicted the existence of both gallium and germanium as well. The elements of the p-block have a disparate and varied history. Their chemical structure, reactivity, and properties vary widely. Nevertheless, in recent years, a better understanding of trends in p-block reactivity, particularly the behavior of those elements not typically found in biological systems, has led to a promising array of emerging applications, highlighted herein.
Collapse
|
37
|
Wu J, Liu X, Hao Y, Chen H, Su P, Wu W, Zhu J. σ-Aromaticity in a Fully Unsaturated Ring. Chem Asian J 2018; 13:3691-3696. [PMID: 30232840 DOI: 10.1002/asia.201801279] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 09/14/2018] [Indexed: 11/07/2022]
Abstract
Aromaticity is one of the most fundamental and fascinating chemical topics, attracting both experimental and theoretical chemists owing to its many manifestations. Both σ- and π-aromaticity can be classified depending on the character of the cyclic electron delocalization. In general, σ-aromaticity stabilizes fully saturated rings with σ-electron delocalization whereas the traditional π-aromaticity describes the π-conjugation in fully unsaturated rings. Here, we demonstrate a strong correlation between nucleus-independent chemical shift (NICS) values and extra cyclic resonance energies (ECREs), which are used to evaluate the σ-aromaticity in an unsaturated three-membered ring (3MR) of cyclopropene, which were computed by molecular orbital (MO) theory and valence bond (VB) theory, respectively. Further study shows that the fully unsaturated ring in methylenecyclopropene and its metallic analogy is σ-aromatic. Our findings revolutionize the fundamental knowledge of the concept of σ-aromaticity, thus opening an avenue to design σ-aromaticity in other fully unsaturated systems, which are traditionally reserved as the domain of π-aromaticity.
Collapse
Affiliation(s)
- Jingjing Wu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Xin Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Yulei Hao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Hongjiang Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Peifeng Su
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Wei Wu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Jun Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| |
Collapse
|
38
|
Transue WJ, Yang J, Nava M, Sergeyev IV, Barnum TJ, McCarthy MC, Cummins CC. Synthetic and Spectroscopic Investigations Enabled by Modular Synthesis of Molecular Phosphaalkyne Precursors. J Am Chem Soc 2018; 140:17985-17991. [DOI: 10.1021/jacs.8b09845] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wesley J. Transue
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Junyu Yang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Matthew Nava
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ivan V. Sergeyev
- Bruker BioSpin Corporation, Billerica, Massachusetts 01821, United States
| | - Timothy J. Barnum
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael C. McCarthy
- Harvard−Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, United States
| | - Christopher C. Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
39
|
Díaz-Tinoco M, Corzo HH, Ortiz JV. Electron Propagator Methods for Vertical Electron Detachment Energies of Anions: Benchmarks and Case Studies. J Chem Theory Comput 2018; 14:5881-5895. [DOI: 10.1021/acs.jctc.8b00736] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Manuel Díaz-Tinoco
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - H. H. Corzo
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - J. V. Ortiz
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| |
Collapse
|
40
|
Yuan QQ, Yang Z, Li RZ, Transue WJ, Li ZP, Jiang L, Govind N, Cummins CC, Wang XB. Magnetic-Bottle and velocity-map imaging photoelectron spectroscopy of APS− (A=C14H10 or anthracene): Electron structure, spin-orbit coupling of APS•, and dipole-bound state of APS−. CHINESE J CHEM PHYS 2018. [DOI: 10.1063/1674-0068/31/cjcp1805114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Qin-qin Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P. O. Box 999, MS K8-88, Richland, Washington 99352, USA
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zheng Yang
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P. O. Box 999, MS K8-88, Richland, Washington 99352, USA
| | - Ren-zhong Li
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P. O. Box 999, MS K8-88, Richland, Washington 99352, USA
| | - Wesley J. Transue
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zhi-peng Li
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P. O. Box 999, MS K8-88, Richland, Washington 99352, USA
| | - Ling Jiang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Niranjan Govind
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P. O. Box 999, MS K8-91, Richland WA 99352, USA
| | - Christopher C. Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P. O. Box 999, MS K8-88, Richland, Washington 99352, USA
| |
Collapse
|
41
|
Janda T, Foroutan‐Nejad C. Why is Benzene Unique? Screening Magnetic Properties of C6H6Isomers. Chemphyschem 2018; 19:2357-2363. [DOI: 10.1002/cphc.201800364] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Tomáš Janda
- Department of Chemistry, Faculty of ScienceMasaryk University Kamenice 5, CZ – 62500 Brno Czech Republic
- Institute of Chemistry and Technology of Macromolecular Materials, Faculty of Chemical TechnologyUniversity of Pardubice
| | - Cina Foroutan‐Nejad
- CEITEC – Central European Institute of Technology, Masaryk University Kamenice 5, CZ – 62500 Brno Czech Republic
| |
Collapse
|
42
|
Sulfur monoxide thermal release from an anthracene-based precursor, spectroscopic identification, and transfer reactivity. Proc Natl Acad Sci U S A 2018; 115:5866-5871. [PMID: 29773708 DOI: 10.1073/pnas.1804035115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sulfur monoxide (SO) is a highly reactive molecule and thus, eludes bulk isolation. We report here on synthesis and reactivity of a molecular precursor for SO generation, namely 7-sulfinylamino-7-azadibenzonorbornadiene (1). This compound has been shown to fragment readily driven by dinitrogen expulsion and anthracene formation on heating in the solid state and in solution, releasing SO at mild temperatures (<100 °C). The generated SO was detected in the gas phase by MS and rotational spectroscopy. In solution, 1 allows for SO transfer to organic molecules as well as transition metal complexes.
Collapse
|
43
|
Zhou X, Huang F, Tang C, Zhuo Q, Chen Z, Zhang H, Xia H. A missing member of conjugated N-heterocycles: realizing pyrido[1,2-α]azepine by reacting ruthenium alkenylcarbene complex with alkyne. Chem Commun (Camb) 2018; 54:4009-4012. [PMID: 29617019 DOI: 10.1039/c8cc00758f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Despite the excellent chemical properties of N-heterocycles, pyrido[1,2-α]azepine remains elusive due to its potential antiaromaticity and lability. Herein, we demonstrate the synthesis and characterization of the first bicyclic pyrido[1,2-α]azepine that leverages the coordination to the ruthenium center to promote the stability of N-bridged bicycle.
Collapse
Affiliation(s)
- Xiaoxi Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | | | | | | | | | | | | |
Collapse
|
44
|
Arhangelskis M, Katsenis AD, Morris AJ, Friščić T. Computational evaluation of metal pentazolate frameworks: inorganic analogues of azolate metal-organic frameworks. Chem Sci 2018; 9:3367-3375. [PMID: 29780467 PMCID: PMC5933226 DOI: 10.1039/c7sc05020h] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/27/2018] [Indexed: 11/21/2022] Open
Abstract
Pentazolate is the ultimate all-nitrogen, inorganic member of the azolate series of aromatic 5-membered ring anions. As an azolate ligand, it has the potential to form open framework structures with metal ions, that would be inorganic analogues of azolate metal-organic frameworks formed by its congeners. However, while the low stability and elusive nature of the pentazolate ion have so far prevented the synthesis of such frameworks, computational studies have focused on pentazolate exclusively as a ligand that would form discrete metallocene structures. Encouraged by the recent first isolation and structural characterization of pentazolate salts and metal complexes stable at ambient conditions, we now explore the role of pentazolate as a framework-forming ligand. We report a computational periodic density-functional theory evaluation of the energetics and topological preferences of putative metal pentazolate frameworks, which also revealed a topologically novel framework structure.
Collapse
Affiliation(s)
- Mihails Arhangelskis
- Department of Chemistry , McGill University , 801 Sherbrooke St. W. H3A 0B8 Montreal , Canada .
| | - Athanassios D Katsenis
- Department of Chemistry , McGill University , 801 Sherbrooke St. W. H3A 0B8 Montreal , Canada .
| | - Andrew J Morris
- School of Metallurgy and Materials , University of Birmingham , Edgbaston , Birmingham B15 2TT , UK
| | - Tomislav Friščić
- Department of Chemistry , McGill University , 801 Sherbrooke St. W. H3A 0B8 Montreal , Canada .
| |
Collapse
|
45
|
Starikova A, Boldyreva NM, Minyaev RM, Boldyrev AI, Minkin VI. Computational Assessment of an Elusive Aromatic N 3P 3 Molecule. ACS OMEGA 2018; 3:286-291. [PMID: 31457893 PMCID: PMC6641276 DOI: 10.1021/acsomega.7b01719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 12/26/2017] [Indexed: 05/09/2023]
Abstract
We computationally proved that the planar aromatic hexagonal isomer N3P3 with the alteration of N and P is the second most stable structure for the N3P3 stoichiometry. We found that the aromatic isomer has high barriers for transition into the global minimum structure or into the three isolated NP molecules, making this structure kinetically stable. We showed that the sandwich N3P3CrN3P3 molecule corresponds to a minimum on the potential energy surface; thus, the aromatic N3P3 molecule has a potential to be a new ligand in chemistry.
Collapse
Affiliation(s)
- Alyona
A. Starikova
- Institute
of Physical and Organic Chemistry, Southern
Federal University, 194/2
Stachka Avenue, 344090 Rostov-on-Don, Russian Federation
| | - Natalia M. Boldyreva
- Institute
of Physical and Organic Chemistry, Southern
Federal University, 194/2
Stachka Avenue, 344090 Rostov-on-Don, Russian Federation
| | - Ruslan M. Minyaev
- Institute
of Physical and Organic Chemistry, Southern
Federal University, 194/2
Stachka Avenue, 344090 Rostov-on-Don, Russian Federation
- E-mail: (R.M.M.)
| | - Alexander I. Boldyrev
- Institute
of Physical and Organic Chemistry, Southern
Federal University, 194/2
Stachka Avenue, 344090 Rostov-on-Don, Russian Federation
- Department
of Chemistry and Biochemistry, Utah State
University, Old Main
Hill 300, Logan, Utah 84322, USA
- E-mail: (A.I.B.)
| | - Vladimir I. Minkin
- Institute
of Physical and Organic Chemistry, Southern
Federal University, 194/2
Stachka Avenue, 344090 Rostov-on-Don, Russian Federation
- E-mail: (V.I.M.)
| |
Collapse
|
46
|
Shida N, Buss JA, Agapie T. Mild electrochemical synthesis of metal phosphides with dibenzo-7-phosphanorbornadiene derivatives: mechanistic insights and application to proton reduction in water. Chem Commun (Camb) 2018; 54:767-770. [DOI: 10.1039/c7cc09003j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Transition metal phosphide films were synthesized using a mild electrochemical method.
Collapse
Affiliation(s)
- Naoki Shida
- Division of Chemistry and Chemical Engineering
- California Institute of Technology
- Pasadena
- USA
| | - Joshua A. Buss
- Division of Chemistry and Chemical Engineering
- California Institute of Technology
- Pasadena
- USA
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering
- California Institute of Technology
- Pasadena
- USA
| |
Collapse
|
47
|
Buss JA, Oyala PH, Agapie T. Terminal Molybdenum Phosphides with d Electrons: Radical Character Promotes Coupling Chemistry. Angew Chem Int Ed Engl 2017; 56:14502-14506. [DOI: 10.1002/anie.201707921] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Joshua A. Buss
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Paul H. Oyala
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| |
Collapse
|
48
|
Buss JA, Oyala PH, Agapie T. Terminal Molybdenum Phosphides with d Electrons: Radical Character Promotes Coupling Chemistry. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201707921] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Joshua A. Buss
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Paul H. Oyala
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| |
Collapse
|
49
|
Schmidt M, Seitz AE, Eckhardt M, Balázs G, Peresypkina EV, Virovets AV, Riedlberger F, Bodensteiner M, Zolnhofer EM, Meyer K, Scheer M. Transfer Reagent for Bonding Isomers of Iron Complexes. J Am Chem Soc 2017; 139:13981-13984. [PMID: 28933848 DOI: 10.1021/jacs.7b07354] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The cothermolysis of As4 and [Cp″2Zr(CO)2] (Cp″ = η5-C5H3tBu2) results in the formation of [Cp″2Zr(η1:1-As4)] (1) in high yields and the arsenic-rich complex [(Cp″2Zr)(Cp″Zr)(μ,η2:2:1-As5)] (2) as a minor product. In contrast to yellow arsenic, 1 is a light-stable, weighable and storable arsenic source for subsequent reactions. The transfer reaction of 1 with [Cp‴Fe(μ-Br)]2 (Cp‴ = η5-C5H2tBu3) yields the unprecedented bond isomeric complexes [(Cp‴Fe)2(μ,η4:4-As4)] (3a) and [(Cp‴Fe)2(μ,η4:4-cyclo-As4)] (3b). In contrast, the analogous reaction with the CpBn derivative [CpBnFe(μ-Br)]2 (CpBn = η5-C5(CH2(C6H5)5) leads exclusively to the triple decker complex [(CpBnFe)2(μ,η4:4-As4)] (4) possessing the tetraarsabutadiene-type ligand analogous to 3a. To elucidate the stability of the bonding isomers 3a and 3b, DFT calculations were performed. The oxidation of 4 with AgBF4 affords [(CpBnFe)2(μ,η5:5-As5)][BF4] (5), which is a product expanded by one arsenic atom, instead of the expected complex [(CpBnFe)2(μ,η4:4-cyclo-As4)]+.
Collapse
Affiliation(s)
- Monika Schmidt
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| | - Andreas E Seitz
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| | - Maria Eckhardt
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| | - Gábor Balázs
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| | - Eugenia V Peresypkina
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany.,Nikolaev Institute of Inorganic Chemistry SB RAS , Novosibirsk 630090, Russia
| | - Alexander V Virovets
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany.,Nikolaev Institute of Inorganic Chemistry SB RAS , Novosibirsk 630090, Russia
| | - Felix Riedlberger
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| | - Michael Bodensteiner
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| | - Eva M Zolnhofer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg , Erlangen 91054, Germany
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg , Erlangen 91054, Germany
| | - Manfred Scheer
- Institute of Inorganic Chemistry, University of Regensburg , Regensburg 93053, Germany
| |
Collapse
|
50
|
Borger JE, Ehlers AW, Slootweg JC, Lammertsma K. Functionalization of P 4 through Direct P-C Bond Formation. Chemistry 2017; 23:11738-11746. [PMID: 28497639 PMCID: PMC5655700 DOI: 10.1002/chem.201702067] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Indexed: 11/20/2022]
Abstract
Research on chlorine-free conversions of P4 into organophosphorus compounds (OPCs) has a long track record, but methods that allow desirable, direct P-C bond formations have only recently emerged. These include the use of metal organyls, carbenes, carboradicals, and photochemical approaches. The versatile product scope enables the preparation of both industrially relevant organophosphorus compounds, as well as a broad range of intriguing new compound classes. Herein we provide a concise overview of recent breakthroughs and outline the acquired fundamental insights to aid future developments.
Collapse
Affiliation(s)
- Jaap E. Borger
- Department of Chemistry and Pharmaceutical SciencesVrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamthe Netherlands
| | - Andreas W. Ehlers
- Department of Chemistry and Pharmaceutical SciencesVrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamthe Netherlands
- Department of ChemistryUniversity of JohannesburgAuckland ParkJohannesburg2006South Africa
- Current address: Van “t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamthe Netherlands
| | - J. Chris Slootweg
- Department of Chemistry and Pharmaceutical SciencesVrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamthe Netherlands
- Current address: Van “t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamthe Netherlands
| | - Koop Lammertsma
- Department of Chemistry and Pharmaceutical SciencesVrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamthe Netherlands
- Department of ChemistryUniversity of JohannesburgAuckland ParkJohannesburg2006South Africa
| |
Collapse
|