1
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Ghosh A, Conradie J. Theoretical Photoelectron Spectroscopy of Metal-Metal Quintuple Bonds: Relativity-Driven Reordering of Frontier Orbitals. ACS ORGANIC & INORGANIC AU 2024; 4:301-305. [PMID: 38855336 PMCID: PMC11157506 DOI: 10.1021/acsorginorgau.4c00002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 02/22/2024] [Accepted: 02/27/2024] [Indexed: 06/11/2024]
Abstract
A recent reinvestigation of the gas-phase photoelectron spectra of Group 6 metal-metal quadruple-bonded complexes with scalar-relativistic DFT calculations showed that common exchange-correlation functionals reproduce the lowest ionization potentials in a semiquantitative manner. The finding encouraged us to undertake a DFT study of metal-metal quintuple bonds in a set of bisamidinato complexes with the formula MI 2[HC(NR)2]2 (M = Cr, Mo, W; R = H, Ph, 2,6-iPr2C6H3) and idealized D 2h symmetry. Scalar-relativistic OLYP/STO-TZ2P calculations indicated significant shifts in valence orbital energies among the three metals, which translate to lower first ionization potentials, higher electron affinities, and lower HOMO-LUMO gaps for the W complexes relative to their Cr and Mo counterparts. These differences are largely attributable to substantially larger relativistic effects in the case of tungsten relative to those of its lighter congeners.
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Affiliation(s)
- Abhik Ghosh
- Department
of Chemistry, UiT − The Arctic University
of Norway, N-9037 Tromsø, Norway
| | - Jeanet Conradie
- Department
of Chemistry, UiT − The Arctic University
of Norway, N-9037 Tromsø, Norway
- Department
of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
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2
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Ghosh A, Conradie J. Theoretical Photoelectron Spectroscopy of Quadruple-Bonded Dimolybdenum(II,II) and Ditungsten(II,II) Paddlewheel Complexes: Performance of Common Density Functional Theory Methods. ACS OMEGA 2024; 9:12237-12241. [PMID: 38496970 PMCID: PMC10938323 DOI: 10.1021/acsomega.4c00269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/13/2024] [Accepted: 02/22/2024] [Indexed: 03/19/2024]
Abstract
We have revisited the gas-phase photoelectron spectra of quadruple-bonded dimolybdenum(II,II) and ditungsten(II,II) paddlewheel complexes with modern density functional theory methods and obtained valuable calibration of four well-known exchange-correlation functionals, namely, BP86, OLYP, B3LYP*, and B3LYP. All four functionals were found to perform comparably, with discrepancies between calculated and experimental ionization potentials ranging from <0.1 to ∼0.5 eV, with the lowest errors observed for the classic pure functional BP86. All four functionals were found to reproduce differences in ionization potentials (IPs) between analogous Mo2 and W2 complexes, as well as large, experimentally observed ligand field effects on the IPs, with near-quantitative accuracy. The calculations help us interpret a number of differences between analogous Mo2 and W2 complexes through the lens of relativistic effects. Thus, relativity results in not only significantly lower IPs for the W2 complexes but also smaller HOMO-LUMO gaps and different triplet states relative to their Mo2 counterparts.
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Affiliation(s)
- Abhik Ghosh
- Department
of Chemistry, UiT − the Arctic University
of Norway, N-9037 Tromsø, Norway
| | - Jeanet Conradie
- Department
of Chemistry, UiT − the Arctic University
of Norway, N-9037 Tromsø, Norway
- Department
of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, Republic
of South Africa
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3
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Conradie J, Alemayehu AB, Ghosh A. Iridium(VII)-Corrole Terminal Carbides Should Exist as Stable Compounds. ACS ORGANIC & INORGANIC AU 2021; 2:159-163. [PMID: 36855452 PMCID: PMC9955125 DOI: 10.1021/acsorginorgau.1c00029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Scalar-relativistic DFT calculations with multiple exchange-correlation functionals and large basis sets foreshadow the existence of stable iridium(VII)-corrole terminal carbide derivatives. For the parent compound Ir[Cor](C), OLYP/STO-TZ2P calculations predict a short Ir-C bond distance of 1.69 Å, a moderately domed macrocycle with no indications of ligand noninnocence, a surprisingly low electron affinity of ∼1.1 eV, and a substantial singlet-triplet gap of ∼1.8 eV. These results, and their essential invariance with respect to the choice of the exchange-correlation functional, lead us to posit that Ir(VII)-corrole terminal carbide complexes should be isolable and indefinitely stable under ambient conditions.
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Affiliation(s)
- Jeanet Conradie
- Department
of Chemistry, UiT The Arctic University
of Norway, N-9037 Tromsø, Norway,Department
of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, Republic of South Africa
| | - Abraham B. Alemayehu
- Department
of Chemistry, UiT The Arctic University
of Norway, N-9037 Tromsø, Norway
| | - Abhik Ghosh
- Department
of Chemistry, UiT The Arctic University
of Norway, N-9037 Tromsø, Norway,
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4
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Einrem RF, Jonsson ET, Teat SJ, Settineri NS, Alemayehu AB, Ghosh A. Regioselective formylation of rhenium-oxo and gold corroles: substituent effects on optical spectra and redox potentials. RSC Adv 2021; 11:34086-34094. [PMID: 35497316 PMCID: PMC9042328 DOI: 10.1039/d1ra05525a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/29/2021] [Indexed: 12/26/2022] Open
Abstract
Vilsmeier-Haack formylation of ReO and Au meso-triarylcorroles over 16-18 hours affords moderate to good yields (47-65%) of the ReO-3-formyl and Au-3,17-diformyl derivatives in a highly regioselective manner. Formylation was found to effect substantial upshifts for redox potentials (especially the reduction potentials) as well as significant to dramatic redshifts for both the Soret and Q bands.
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Affiliation(s)
- Rune F Einrem
- Department of Chemistry, UiT - The Arctic University of Norway N-9037 Tromsø Norway
| | - Einar Torfi Jonsson
- Department of Chemistry, UiT - The Arctic University of Norway N-9037 Tromsø Norway
| | - Simon J Teat
- Advanced Light Source, Lawrence Berkeley National Laboratory Berkeley CA 94720-8229 USA
| | - Nicholas S Settineri
- Advanced Light Source, Lawrence Berkeley National Laboratory Berkeley CA 94720-8229 USA
- Department of Chemistry, University of California, Berkeley Berkeley California 94720 USA
| | - Abraham B Alemayehu
- Department of Chemistry, UiT - The Arctic University of Norway N-9037 Tromsø Norway
| | - Abhik Ghosh
- Department of Chemistry, UiT - The Arctic University of Norway N-9037 Tromsø Norway
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5
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Yadav P, Nigel-Etinger I, Kumar A, Mizrahi A, Mahammed A, Fridman N, Lipstman S, Goldberg I, Gross Z. Hydrogen evolution catalysis by terminal molybdenum-oxo complexes. iScience 2021; 24:102924. [PMID: 34430813 PMCID: PMC8367842 DOI: 10.1016/j.isci.2021.102924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/28/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
Stable complexes with terminal triply bound metal-oxygen bonds are usually not considered as valuable catalysts for the hydrogen evolution reaction (HER). We now report the preparation of three conceptually different (oxo)molybdenum(V) corroles for testing if proton-assisted 2-electron reduction will lead to hyper-reactive molybdenum(III) capable of converting protons to hydrogen gas. The upto 670 mV differences in the [(oxo)Mo(IV)]-/[(oxo)Mo(III)]-2 redox potentials of the dissolved complexes came into effect by the catalytic onset potential for proton reduction thereby, significantly earlier than their reduction process in the absence of acids, but the two more promising complexes were not stable at practical conditions. Under heterogeneous conditions, the smallest and most electron-withdrawing catalyst did excel by all relevant criteria, including a 97% Faradaic efficiency for catalyzing HER from acidic water. This suggests complexes based on molybdenum, the only sustainable heavy transition metal, as catalysts for other yet unexplored green-energy-relevant processes.
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Affiliation(s)
- Pinky Yadav
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | - Izana Nigel-Etinger
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | - Amit Kumar
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | - Amir Mizrahi
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
- Chemistry Department, Nuclear Research Centre Negev, Beer Sheva 84190, Israel
| | - Atif Mahammed
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | - Natalia Fridman
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | - Sophia Lipstman
- School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Israel Goldberg
- School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Zeev Gross
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
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Alemayehu AB, Thomas KE, Einrem RF, Ghosh A. The Story of 5d Metallocorroles: From Metal-Ligand Misfits to New Building Blocks for Cancer Phototherapeutics. Acc Chem Res 2021; 54:3095-3107. [PMID: 34297542 PMCID: PMC8382219 DOI: 10.1021/acs.accounts.1c00290] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
Porphyrin chemistry is Shakespearean: over a
century of study has
not withered the field’s apparently infinite variety. Heme
proteins continually astonish us with novel molecular mechanisms,
while new porphyrin analogues bowl us over with unprecedented optical,
electronic, and metal-binding properties. Within the latter domain,
corroles occupy a special place, exhibiting a unique and rich coordination
chemistry. The 5d metallocorroles are arguably the icing on that cake. New Zealand chemist Penny Brothers has used the word “misfit”
to describe the interactions of boron, a small atom with a predilection
for tetrahedral coordination, and porphyrins, classic square-planar
ligands. Steve Jobs lionized misfits as those who see things differently
and push humanity forward. Both perspectives have inspired us. The
5d metallocorroles are misfits in that they encapsulate a large 5d
transition metal ion within the tight cavity of a contracted porphyrin
ligand. Given the steric mismatch inherent in their structures,
the syntheses
of some 5d metallocorroles are understandably capricious,
proceeding under highly specific conditions and affording poor yields.
Three broad approaches may be distinguished. (a) In the metal–alkyl approach, a free-base
corrole is exposed to an alkyllithium and the resulting lithio-corrole
is treated with an early transition metal chloride; a variant of the
method eschews alkyllithium and deploys a transition metal–alkyl
instead, resulting in elimination of the alkyl group as an alkane
and insertion of the metal into the corrole. This approach is useful
for inserting transition metals from groups 4, 5, and, to some extent,
6, as well as lanthanides and actinides. (b) In our laboratory,
we have often deployed a low-valent
organometallic approach for the middle transition elements
(groups 6, 7, 8, and 9). The reagents are low-valent metal–carbonyl
or −olefin complexes, which lose one or more carbon ligands
at high temperature, affording coordinatively unsaturated, sticky
metal fragments that are trapped by the corrole nitrogens. (c)
Finally, a metal acetate approach provides
the method of choice for gold and platinum insertion (groups 10 and
11). This Account provides a first-hand perspective
of the three approaches, focusing on the last two, which were largely
developed in our laboratory. In general, the products were characterized
with X-ray crystallography, electrochemistry, and a variety of spectroscopic
methods. The physicochemical data, supplemented by relativistic DFT
calculations, have provided fascinating insights into periodic trends
and relativistic effects. An unexpected feature of many 5d metallocorroles,
given their misfit
character, is their remarkable stability under thermal, chemical,
and photochemical stimulation. Many of them also exhibit long triplet
lifetimes on the order of 100 μs and effectively sensitize singlet
oxygen formation. Many exhibit phosphorescence in the near-infrared
under ambient conditions. Furthermore, water-soluble ReO and Au corroles
exhibit impressive photocytotoxicity against multiple cancer cell
lines, promising potential applications as cancer phototherapeutics.
We thus envision a bright future for the compounds as rugged building
blocks for new generations of therapeutic and diagnostic (theranostic)
agents.
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Affiliation(s)
- Abraham B. Alemayehu
- Department of Chemistry, UiT—The Arctic University of Norway, N-9037 Tromso, Norway
| | - Kolle E. Thomas
- Department of Chemistry, UiT—The Arctic University of Norway, N-9037 Tromso, Norway
| | - Rune F. Einrem
- Department of Chemistry, UiT—The Arctic University of Norway, N-9037 Tromso, Norway
| | - Abhik Ghosh
- Department of Chemistry, UiT—The Arctic University of Norway, N-9037 Tromso, Norway
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7
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Braband H, Benz M, Spingler B, Conradie J, Alberto R, Ghosh A. Relativity as a Synthesis Design Principle: A Comparative Study of [3 + 2] Cycloaddition of Technetium(VII) and Rhenium(VII) Trioxo Complexes with Olefins. Inorg Chem 2021; 60:11090-11097. [PMID: 34255507 PMCID: PMC8388117 DOI: 10.1021/acs.inorgchem.1c00995] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
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The difference in [3 + 2] cycloaddition reactivity between fac-[MO3(tacn)]+ (M = Re, 99Tc; tacn = 1,4,7-triazacyclononane) complexes has been reexamined
with a selection of unsaturated substrates including sodium 4-vinylbenzenesulfonate,
norbornene, 2-butyne, and 2-methyl-3-butyn-2-ol (2MByOH). None of
the substrates was found to react with the Re cation in water at room
temperature, whereas the 99Tc reagent cleanly yielded the [3 + 2] cycloadducts. Interestingly,
a bis-adduct was obtained as the sole product for 2MByOH, reflecting
the high reactivity of a 99TcO-enediolato monoadduct. On
the basis of scalar relativistic and nonrelativistic density functional
theory calculations of the reaction pathways, the dramatic difference
in reactivity between the two metals has now been substantially attributed to differences in relativistic effects, which are much
larger for the 5d metal. Furthermore, scalar-relativistic ΔG values were found to decrease along the series propene
> norbornene > 2-butyne > dimethylketene, indicating major variations
in the thermodynamic driving force as a function of the unsaturated
substrate. The suggestion is made that scalar-relativistic effects,
consisting of greater destabilization of the valence electrons of
the 5d elements compared with those of the 4d elements, be viewed
as a new design principle for novel 99mTc/Re radiopharmaceuticals,
as well as more generally in heavy-element coordination chemistry. Room temperature cycloaddition reactivity of fac-[99TcO3(tacn)]+ (tacn = 1,4,7-triazacyclononane)
with a variety of unsaturated substrates and the lack of such reactivity
for fac-[ReO3(tacn)]+ appears
largely attributable to much stronger relativistic effects for Re
relative to Tc, based on relativistic density functional theory calculations.
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Affiliation(s)
- Henrik Braband
- Department of Chemistry, University of Zurich, Zürich 8057, Switzerland
| | - Michael Benz
- Department of Chemistry, University of Zurich, Zürich 8057, Switzerland
| | - Bernhard Spingler
- Department of Chemistry, University of Zurich, Zürich 8057, Switzerland
| | - Jeanet Conradie
- Department of Chemistry, UiT-The Arctic University of Norway, Tromsø N-9037, Norway.,Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
| | - Roger Alberto
- Department of Chemistry, University of Zurich, Zürich 8057, Switzerland
| | - Abhik Ghosh
- Department of Chemistry, UiT-The Arctic University of Norway, Tromsø N-9037, Norway
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8
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Kumar Maurya Y, Wei P, Shimada T, Yamasumi K, Mori S, Furukawa K, Kusaba H, Ishihara T, Xie Y, Ishida M, Furuta H. Chiral Interlocked Corrole Dimers Directly Linked at Inner Carbon Atoms of Confused Pyrrole Rings. Chem Asian J 2021; 16:743-747. [PMID: 33624937 DOI: 10.1002/asia.202100083] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/23/2021] [Indexed: 12/13/2022]
Abstract
A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face-to-face intramolecularly interlocked corrole dimers were formed by the oxidative C-C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials.
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Affiliation(s)
- Yogesh Kumar Maurya
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan
| | - Pingchun Wei
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan
| | - Takahide Shimada
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan
| | - Kazuhisa Yamasumi
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan
| | - Shigeki Mori
- Advanced Research Support Center, Ehime University, Matsuyama, 790-8577, Japan
| | - Ko Furukawa
- Center for Instrumental Analysis, Niigata University, Niigata, 950-2181, Japan
| | - Hajime Kusaba
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka, 819-0395, Japan
| | - Tatsumi Ishihara
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka, 819-0395, Japan
| | - Yongshu Xie
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, State Key Laboratory of Bioreactor Engineering, Laboratory of Pharmaceutical Crystal Engineering & Technology, School of Pharmacy, East China University of Science & Technology, 200237, Shanghai, P. R. China
| | - Masatoshi Ishida
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan
| | - Hiroyuki Furuta
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan
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9
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Nayak M, Nayak P, Sahu K, Kar S. Synthesis, Characterization, and Application of Oxo-Molybdenum(V)-Corrolato Complexes in Epoxidation Reactions. J Org Chem 2020; 85:11654-11662. [PMID: 32808776 DOI: 10.1021/acs.joc.0c01146] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sharpless et al. have described, while performing the molybdenum-catalyzed epoxidation reaction of olefins using alkyl hydroperoxides, that the molybdenum-oxo moiety is an active catalytic species. Thus, continuous efforts have been made to synthesize molybdenum-oxo complexes of different ligand environments. While plenty of such works on molybdenum porphyrins are reported in the literature, related molybdenum corroles are very less reported. The synthesis and characterization of two new oxo-molybdenum(V)-corrolato complexes are described herein. Both the complexes have been fully characterized by several spectroscopic techniques in conjunction with single-crystal X-ray diffraction analysis. The efficacy of the oxo-molybdenum(V)-corrolato complexes for the catalytic epoxidation reaction of olefins with the help of hydroperoxides has also been explored. The catalytic application of oxo-molybdenum(V)-corrolato complexes in the epoxidation reaction has not been reported earlier. A mechanism has been proposed to explain the experimental findings.
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Affiliation(s)
- Manisha Nayak
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar 752050, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Panisha Nayak
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar 752050, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Kasturi Sahu
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar 752050, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Sanjib Kar
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar 752050, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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10
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Abstract
Metallocorroles involving 5d transition metals are currently of interest as near-IR phosphors and as photosensitizers for oxygen sensing and photodynamic therapy. Their syntheses, however, are often bedeviled by capricious and low-yielding protocols. Against this backdrop, we describe rhenium-imido corroles, a new class of 5d metallocorroles, synthesized simply and in respectable (∼30%) yields via the interaction of a free-base corrole, Re2(CO)10, K2CO3, and aniline in 1,2,4-trichlorobenzene at ∼190 °C in a sealed vial under strict anaerobic conditions. The generality of the method was shown by the synthesis of six derivatives, including those derived from meso-tris(pentafluorophenyl)corrole, H3[TPFPC], and five different meso-tris(p-X-phenyl)corroles, H3[TpXPC], where X = CF3, F, H, CH3, OCH3. Single-crystal X-ray structures obtained for two of the complexes, Re[TpFPC](NPh) and Re[TpCF3PC](NPh), revealed relatively unstrained equatorial Re-N distances of ∼2.00 Å, a ∼ 0.7-Å displacement of the Re from the mean plane of the corrole nitrogens, and an Re-Nimido distance of ∼1.72 Å. Details of the corrole skeletal bond distances, diamagnetic 1H NMR spectra, relatively substituent-independent Soret maxima, and electrochemical HOMO-LUMO gaps of ∼2.2 V all indicated an innocent corrole macrocycle. Surprisingly, unlike several other classes of 5d metallocorroles, the Re-imido complexes proved nonemissive in solution at room temperature and also failed to sensitize singlet oxygen formation, indicating rapid radiationless deactivation of the triplet state, presumably via the rapidly rotating axial phenyl group. By analogy with other metal-oxo and -imido corroles, we remain hopeful that the Re-imido group will prove amenable to further elaboration and thereby contribute to the development of a somewhat challenging area of coordination chemistry.
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Affiliation(s)
- Abraham B Alemayehu
- Department of Chemistry, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Simon J Teat
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720-8229, United States
| | - Sergey M Borisov
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Abhik Ghosh
- Department of Chemistry, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
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11
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Alemayehu AB, Vazquez‐Lima H, Teat SJ, Ghosh A. Unexpected Molecular Structure of a Putative Rhenium-Dioxo-Benzocarbaporphyrin Complex. Implications for the Highest Transition Metal Valence in a Porphyrin-Type Ligand Environment. ChemistryOpen 2019; 8:1298-1302. [PMID: 31649839 PMCID: PMC6804418 DOI: 10.1002/open.201900271] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 09/25/2019] [Indexed: 01/08/2023] Open
Abstract
A combination of quantum chemical calculations and synthetic studies was used to address the possibility of very high (>6) valence states of transition metals in porphyrin-type complexes. With corrole as a supporting ligand, DFT calculations ruled out Re(VII) and Ir(VII) dioxo complexes as stable species. Attempted rhenium insertion into benzocarbaporphyrin (BCP) ligands on the other hand led to two products with different stoichiometries - Re[BCP]O and Re[BCP]O2. To our surprise, single-crystal structure determination of one of the complexes of the latter type indicated an ReVO center with a second oxygen bridging the Re-C bond. In other words, although the monooxo complexes Re[BCP]O are oxophilic, the BCP ligand cannot sustain a trans-ReVII(O)2 center. The search for metal valence states >6 in porphyrin-type ligand environments must therefore continue.
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Affiliation(s)
| | - Hugo Vazquez‐Lima
- Centro de Química, Instituto de CienciasUniversidad Autónoma de Puebla Edif. IC9, CU, San Manuel72570Puebla, PueblaMexico
| | - Simon J. Teat
- Advanced Light SourceLawrence Berkeley National LaboratoryBerkeleyCA 94720–8229USA
| | - Abhik Ghosh
- Department of ChemistryUiT – The Arctic University of Norway9037TromsøNorway
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12
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Abstract
Noninnocent ligands do not allow an unambiguous definition of the oxidation state of a coordinated atom. When coordinated, the ligands also cannot be adequately represented by a classic Lewis structure. A noninnocent system thus harbors oxidizing (holes) or reducing equivalents (electrons) that are delocalized over both the ligand and the coordinated atom. To a certain degree, that is true of all complexes, but the phenomenon is arguably most conspicuous in complexes involving ligands with extended π-systems. The electronic structures of such systems have often been mischaracterized, thereby muddying the chemical literature to the detriment of students and newcomers to the field. In recent years, we have investigated the electronic structures of several metallocorrole families, several of which have turned out to be noninnocent. Our goal here, however, is not to present a systematic account of the different classes of metallocorroles, but rather to focus on seven major tools (in a nod to A. G. Cairns-Smith's Seven Clues to the Origin of Life) that led us to recognize noninnocent behavior and subsequently to characterize the phenomenon in depth. (1) The optical probe: For a series of noninnocent meso-triarylcorrole derivatives with different para substituents X, the Soret maxima are typically exquisitely sensitive to the nature of X, red-shifting with increasing electron-donating character of the group. No such substituent sensitivity is observed for the Soret maxima of innocent triarylcorrole derivatives. (2) Quantum chemistry: Spin-unrestricted density functional theory calculations permit a simple and quick visualization of ligand noninnocence in terms of the spin density profile. Even for an S = 0 complex, the broken-symmetry method often affords a spin density profile that, its fictitious character notwithstanding, helps visualize the intramolecular spin couplings. (3) NMR and EPR spectroscopy: In principle, these two techniques afford experimental probes of the electronic spin density. (4) Structure/X-ray crystallography. Ligand noninnocence in metallocorroles is often reflected in small but distinct skeletal bond length alternations in and around the bipyrrole part of the macrocycle. In addition, for Cu and some Ag corroles, ligand noninnocence manifests itself via a strong saddling of the macrocycle. (5) Vibrational spectroscopy. Unsurprisingly, the aforementioned bond length alternations translate to structure-sensitive vibrational marker bands. (6) Electrochemistry. Noninnocent metallocorroles exhibit characteristically high reduction potentials, but caution should be exercised in turning the logic around. A high reduction potential does not necessarily signify a noninnocent metallocorrole; certain high-valent metal centers also undergo metal-centered reduction at quite high potentials. (7) X-ray absorption spectroscopy (XAS). By focusing on a given element, typically the central atom in a coordination complex, X-ray absorption near-edge spectroscopy (XANES) can provide uniquely detailed local information on oxidation and spin states, ligand field strength, and degree of centrosymmetry. For metallocorroles, some of the most clear-cut distinctions between innocent and noninnocent systems have come from the K-edge XANES of Mn and Fe corroles. For researchers faced with a new, potentially noninnocent system, the take-home message is to employ a good majority (i.e., at least four) of the above methods to arrive at a reliable conclusion vis-à-vis noninnocence.
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Affiliation(s)
- Sumit Ganguly
- Department of Chemistry and Arctic Center for Sustainable Energy, UiT−The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Abhik Ghosh
- Department of Chemistry and Arctic Center for Sustainable Energy, UiT−The Arctic University of Norway, N-9037 Tromsø, Norway
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13
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Lim H, Thomas KE, Hedman B, Hodgson KO, Ghosh A, Solomon EI. X-ray Absorption Spectroscopy as a Probe of Ligand Noninnocence in Metallocorroles: The Case of Copper Corroles. Inorg Chem 2019; 58:6722-6730. [PMID: 31046257 PMCID: PMC6644708 DOI: 10.1021/acs.inorgchem.9b00128] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The question of ligand noninnocence in Cu corroles has long been a topic of discussion. Presented herein is a Cu K-edge X-ray absorption spectroscopy (XAS) study, which provides a direct probe of the metal oxidation state, of three Cu corroles, Cu[TPC], Cu[Br8TPC], and Cu[(CF3)8TPC] (TPC = meso-triphenylcorrole), and the analogous Cu(II) porphyrins, Cu[TPP], Cu[Br8TPP], and Cu[(CF3)8TPP] (TPP = meso-tetraphenylporphyrin). The Cu K rising-edges of the Cu corroles were found to be about 0-1 eV upshifted relative to the analogous porphyrins, which is substantially lower than the 1-2 eV shifts typically exhibited by authentic Cu(II)/Cu(III) model complex pairs. In an unusual twist, the Cu K pre-edge regions of both the Cu corroles and the Cu porphyrins exhibit two peaks split by 0.8-1.3 eV. Based on time-dependent density functional theory calculations, the lower- and higher-energy peaks were assigned to a Cu 1s → 3d x2- y2 transition and a Cu 1s → corrole/porphyrin π* transition, respectively. From the Cu(II) porphyrins to the corresponding Cu corroles, the energy of the Cu 1s → 3d x2- y2 transition peak was found to upshift by 0.6-0.8 eV. This shift is approximately half that observed between Cu(II) to Cu(III) states for well-defined complexes. The Cu K-edge XAS spectra thus show that although the metal sites in the Cu corroles are more oxidized relative to those in their Cu(II) porphyrin analogues, they are not oxidized to the Cu(III) level, consistent with the notion of a noninnocent corrole. The relative importance of σ-donation versus corrole π-radical character is discussed.
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Affiliation(s)
- Hyeongtaek Lim
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Kolle E. Thomas
- Department of Chemistry, UiT — The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Keith O. Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Abhik Ghosh
- Department of Chemistry, UiT — The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
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14
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Alemayehu AB, McCormick LJ, Vazquez-Lima H, Ghosh A. Relativistic Effects on a Metal-Metal Bond: Osmium Corrole Dimers. Inorg Chem 2019; 58:2798-2806. [PMID: 30730723 DOI: 10.1021/acs.inorgchem.8b03391] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of metal-metal bonded osmium corrole dimers, {Os[T pXPC]}2, were synthesized in reasonably good yields (35-46%) via the interaction of the corresponding free-base meso-tris( p-X-phenyl)corroles (H3[T pXPC], X = CF3, H, CH3, and OCH3), Os3(CO)12, and potassium carbonate in 1,2,4-trichlorobenzene under an inert atmosphere at 180 °C over several hours. The complexes are only the second class of Os corroles reported to date (the first being OsVIN corroles) and also the second class of metal-metal bonded metallocorrole dimers (the other being Ru corrole dimers). Comparison of the X-ray structures, redox potentials, and optical spectra of analogous Ru and Os corrole dimers, along with scalar-relativistic DFT calculations, has provided an experimentally calibrated account of relativistic effects in these complexes. Three of the Os corrole dimers (X = CF3, H, and OCH3) were analyzed with single-crystal X-ray diffraction analysis, revealing inversion-related corrole rings with eclipsed Os-N bonds and Os-Os distances of ∼2.24 Å that are ∼0.06 Å longer than the Ru-Ru distances in the analogous Ru corrole dimers. Interestingly, a comparison of scalar-relativistic and nonrelativistic DFT calculations indicates that this difference in metal-metal bond distance does not, in fact, reflect a differential relativistic effect. For a given corrole ligand, the Ru and Os corrole dimers exhibit nearly identical oxidation potentials but dramatically different reduction potentials, with the Os values ∼0.5 V lower relative to Ru, suggesting that whereas oxidation occurs in a ligand-centered manner, reduction is substantially metal-centered, which indeed was confirmed by scalar-relativistic calculations. The calculations further indicate that approximately a third of the ∼0.5 V difference in reduction potentials can be ascribed to relativity. The somewhat muted value of this relativistic effect appears to be related to the finding that reduction of an Os corrole dimer is not exclusively metal-based but that a significant amount of spin density is delocalized over to the corrole ligand; in contrast, reduction of an Ru corrole dimer occurs exclusively on the Ru-Ru linkage. For isoelectronic complexes, the Ru and Os corrole dimers exhibit substantially different UV-vis spectra. A key difference is a strong near-UV feature of the Os series, which in energy terms is blue-shifted by ∼0.55 V relative to the analogous feature of the Ru series. TDDFT calculations suggest that this difference may be related to higher-energy Os(5d)-based LUMOs in the Os case relative to analogous MOs for Ru.
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Affiliation(s)
- Abraham B Alemayehu
- Department of Chemistry , UiT - The Arctic University of Norway , N-9037 Tromsø , Norway
| | - Laura J McCormick
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720-8229 , United States
| | - Hugo Vazquez-Lima
- Department of Chemistry , UiT - The Arctic University of Norway , N-9037 Tromsø , Norway
| | - Abhik Ghosh
- Department of Chemistry , UiT - The Arctic University of Norway , N-9037 Tromsø , Norway
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15
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Liu W, Zeng S, Chen X, Pan H, Qi D, Wang K, Dou J, Jiang J. Hemiporphyrazine-Involved Sandwich Dysprosium Double-Decker Single-Ion Magnets. Inorg Chem 2018; 57:12347-12353. [PMID: 30230324 DOI: 10.1021/acs.inorgchem.8b02068] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Both heteroleptic (phthalocyaninato)(hemiporphyrazinato) and homoleptic bis(hemiporphyrazinato) dysprosium double-decker complexes, Dy[H(Hp)2] (1) and Dy[H(Pc)(Hp)] (2) (H2Pc = metal-free phthalocyanine; H2Hp = metal-free hemiporphyrazine), were designed, synthesized, and structurally characterized. The dysprosium center in both double-deckers are octa-coordinated with a nearly ideal square-antiprismatic coordination geometry, which provides an increased molecular anisotropy for the dysprosium ion and ensures the strengthened magnetic properties of both single-ion magnets (SIMs) in terms of coordination geometry. Magnetic studies reveal that both double-deckers exhibit typical SIM behavior with a spin reversal energy barrier of 80.1 ± 6.3 K for 1 and 57.3 ± 3.8 K for 2 as well as the hysteresis loops emerging at 3 K. In particular, introduction of two Hp ligands with four pyridine nitrogen atoms coordinated with the dysprosium spin center endows Dy[H(Hp)2] (1) with the thus far highest energy barrier among the sandwich-type dysprosium SIMs with N4-macrocyclic ligands, revealing the potential applications of sandwich-type lanthanide complexes with Hp ligands in molecular-based information storage.
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Affiliation(s)
- Wenbo Liu
- Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
| | - Suyuan Zeng
- Department of Chemistry , Liaocheng University , Liaocheng , 252059 , China
| | - Xin Chen
- Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
| | - Houhe Pan
- Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
| | - Dongdong Qi
- Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
| | - Kang Wang
- Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
| | - Jianmin Dou
- Department of Chemistry , Liaocheng University , Liaocheng , 252059 , China
| | - Jianzhuang Jiang
- Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
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16
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Demissie TB, Conradie J, Vazquez-Lima H, Ruud K, Ghosh A. Rare and Nonexistent Nitrosyls: Periodic Trends and Relativistic Effects in Ruthenium and Osmium Porphyrin-Based {MNO} 7 Complexes. ACS OMEGA 2018; 3:10513-10516. [PMID: 31459176 PMCID: PMC6645279 DOI: 10.1021/acsomega.8b01434] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 08/14/2018] [Indexed: 05/26/2023]
Abstract
Relativistic and nonrelativistic density functional theory calculations were used to investigate rare or nonexistent ruthenium and osmium analogues of nitrosylhemes. Strong ligand field effects and, to a lesser degree, relativistic effects were found to destabilize {RuNO}7 porphyrins relative to their {FeNO}7 analogues. Substantially stronger relativistic effects account for the even greater instability and/or nonexistence of {OsNO}7 porphyrin derivatives.
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Affiliation(s)
- Taye B. Demissie
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Tromsø—The Arctic University
of Norway, N-9037 Tromsø, Norway
- Materials
Science Program, Department of Chemistry, Addis Ababa University, Addis
Ababa, Ethiopia
| | - Jeanet Conradie
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Tromsø—The Arctic University
of Norway, N-9037 Tromsø, Norway
- Department
of Chemistry, University of the Free State, P.O. Box 339, 9300 Bloemfontein, Republic of South Africa
| | - Hugo Vazquez-Lima
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Tromsø—The Arctic University
of Norway, N-9037 Tromsø, Norway
| | - Kenneth Ruud
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Tromsø—The Arctic University
of Norway, N-9037 Tromsø, Norway
| | - Abhik Ghosh
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Tromsø—The Arctic University
of Norway, N-9037 Tromsø, Norway
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17
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Alemayehu A, M cCormick LJ, Gagnon KJ, Borisov SM, Ghosh A. Stable Platinum(IV) Corroles: Synthesis, Molecular Structure, and Room-Temperature Near-IR Phosphorescence. ACS OMEGA 2018; 3:9360-9368. [PMID: 31459069 PMCID: PMC6645213 DOI: 10.1021/acsomega.8b01149] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 08/01/2018] [Indexed: 05/17/2023]
Abstract
A series of stable Pt(IV) corrole complexes with the general formula PtIV[TpXPC](m/p-C6H4CN)(py), where TpXPC3- is the trianion of a tris(p-X-phenyl)corrole and X = CF3, H, and CH3, has been synthesized, affording key physicochemical data on a rare and elusive class of metallocorroles. Single-crystal X-ray structures of two of the complexes revealed very short equatorial Pt-N distances of 1.94-1.97 Å, an axial Pt-C distance of ∼2.03 Å, and an axial Pt-N distance of ∼2.22 Å. The complexes exhibit Soret maxima at ∼430 nm, which are essentially independent of the meso-aryl para substituents, and strong Q bands with the most intense peak at 595-599 nm. The substituent-independent Soret maxima are consistent with an innocent PtIV-corrole3- description for the complexes. The low reduction potentials (-1.45 ± 0.08 V vs saturated calomel reference electrode) also support a highly stable Pt(IV) ground state as opposed to a noninnocent corrole•2- description. The reductions, however, are irreversible, which suggests that they involve concomitant cleavage of the Pt-aryl bond. Unlike Pt(IV) porphyrins, two of the complexes, PtIV[TpXPC](m-C6H4CN)(py) (X = CF3 and CH3), were found to exhibit room-temperature near-IR phosphorescence with emission maxima at 813 and 826 nm, respectively. The quantum yield of ∼0.3% is comparable to those observed for six-coordinate Ir(III) corroles.
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Affiliation(s)
- Abraham
B. Alemayehu
- Department
of Chemistry, UiT—The Arctic University
of Norway, N-9037 Tromsø, Norway
| | - Laura J. McCormick
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720-8229, United States
| | - Kevin J. Gagnon
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720-8229, United States
| | - Sergey M. Borisov
- Institute
of Analytical Chemistry and Food Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Abhik Ghosh
- Department
of Chemistry, UiT—The Arctic University
of Norway, N-9037 Tromsø, Norway
- E-mail:
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18
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Schies C, Alemayehu AB, Vazquez-Lima H, Thomas KE, Bruhn T, Bringmann G, Ghosh A. Metallocorroles as inherently chiral chromophores: resolution and electronic circular dichroism spectroscopy of a tungsten biscorrole. Chem Commun (Camb) 2018; 53:6121-6124. [PMID: 28530281 DOI: 10.1039/c7cc02027a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An inherently chiral metallocorrole has been resolved for the first time by means of HPLC on a chiral stationary phase. For the compound in question, a homoleptic tungsten biscorrole, the absolute configurations of the enantiomers were assigned using online HPLC-ECD measurements in conjunction with time-dependent CAM-B3LYP calculations, which provided accurate simulations of the ECD spectra.
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Affiliation(s)
- Christine Schies
- Institute of Organic Chemistry, University of Würzburg, 97074 Würzburg, Germany.
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