1
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Keil P, Ezendu S, Schulz A, Kubisz M, Szilvási T, Hadlington TJ. Thermodynamic Modulation of Dihydrogen Activation Through Rational Ligand Design in Ge II-Ni 0 Complexes. J Am Chem Soc 2024; 146:23606-23615. [PMID: 39106297 PMCID: PMC11345810 DOI: 10.1021/jacs.4c08297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Revised: 07/19/2024] [Accepted: 07/22/2024] [Indexed: 08/09/2024]
Abstract
A family of chelating aryl-functionalized germylene ligands has been developed and employed in the synthesis of their corresponding 16-electron Ni0 complexes (PhiPDippGeAr·Ni·IPr; PhiPDipp = {[Ph2PCH2Si(iPr)2](Dipp)N}-; IPr = [{(H)CN(Dipp)}2C:]; Dipp = 2,6-iPr2C6H3). These complexes demonstrate the ability to cooperatively and reversibly activate dihydrogen at the germylene-nickel interface under mild conditions (1.5 atm H2, 298 K). We show that the thermodynamics of the dihydrogen activation process can be modulated by tuning the electronic nature of the germylene ligands, with an increase in the electron-withdrawing character displaying more exergonic ΔG298 values, as ascertained through NMR spectroscopic Van't Hoff analyses for all systems. This is also shown to correlate with experimental 31P NMR and UV/vis absorption data as well as with computationally derived parameters such as Ge-Ni bond order and Ni/Ge NPA charge, giving a thorough understanding of the modulating effect of ligand design on this reversible, cooperative bond activation reaction. Finally, the utility of this modulation was demonstrated in the catalytic dehydrocoupling of phenylsilane, whereby systems that disfavor dihydrogen activation are more efficient catalysts, aligning with H2-elimination being the rate-limiting step. A density functional theory analysis supports cooperative activation of the Si-H moiety in PhSiH3.
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Affiliation(s)
- Philip
M. Keil
- Fakultät
für Chemie, Technische Universität
München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
| | - Sophia Ezendu
- Department
of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Annika Schulz
- Fakultät
für Chemie, Technische Universität
München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
| | - Malte Kubisz
- Fakultät
für Chemie, Technische Universität
München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
| | - Tibor Szilvási
- Department
of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Terrance J. Hadlington
- Fakultät
für Chemie, Technische Universität
München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
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2
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Kameo H, Miyazaki T, Shimoyama Y, Asada A, Izumi D, Matsuzaka H, Bourissou D. Trigonal-Bipyramidal Pt(0) and Pd(0) Anions. Inorg Chem 2024; 63:13186-13190. [PMID: 38976600 DOI: 10.1021/acs.inorgchem.4c01884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Anionic Pt(0) and Pd(0) complexes with unprecedented trigonal-bipyramidal geometry have been prepared and thoroughly characterized by experimental and computational means. Coordination of a σ-acceptor borane moiety supported by three phosphine buttresses enhances the electrophilicity of M(0) and triggers the binding of soft anions (X = Br, I, CN).
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Affiliation(s)
- Hajime Kameo
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Osaka 558-8585, Japan
| | - Tokoro Miyazaki
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Osaka 558-8585, Japan
| | - Yoshihiro Shimoyama
- Interdisciplinary Research Center for Catalytic Chemistry, National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba, Ibaraki 305-8565 Japan
| | - Ayaka Asada
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Osaka 558-8585, Japan
| | - Daisuke Izumi
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Osaka 558-8585, Japan
| | - Hiroyuki Matsuzaka
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Osaka 558-8585, Japan
| | - Didier Bourissou
- Laboratoire Hétérochimie Fondamentale et Appliquée, UMR 5069, CNRS, Université Toulouse III Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 09, France
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3
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Sansores-Paredes MLG, Lutz M, Moret ME. Cooperative H 2 activation at a nickel(0)-olefin centre. Nat Chem 2024; 16:417-425. [PMID: 38052947 DOI: 10.1038/s41557-023-01380-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 10/23/2023] [Indexed: 12/07/2023]
Abstract
Catalytic olefin hydrogenation is ubiquitous in organic synthesis. In most proposed homogeneous catalytic cycles, reactive M-H bonds are generated either by oxidative addition of H2 to a metal centre or by deprotonation of a non-classical metal dihydrogen (M-H2) intermediate. Here we provide evidence for an alternative H2-activation mechanism that instead involves direct ligand-to-ligand hydrogen transfer (LLHT) from a metal-bound H2 molecule to a metal-coordinated olefin. An unusual pincer ligand that features two phosphine ligands and a central olefin supports the formation of a non-classical Ni-H2 complex and the Ni(alkyl)(hydrido) product of LLHT, in rapid equilibrium with dissolved H2. The usefulness of this cooperative H2-activation mechanism for catalysis is demonstrated in the semihydrogenation of diphenylacetylene. Experimental and computational mechanistic investigations support the central role of LLHT for H2 activation and catalytic semihydrogenation. The product distribution obtained is largely determined by the competition between (E)-(Z) isomerization and catalyst degradation by self-hydrogenation.
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Affiliation(s)
- María L G Sansores-Paredes
- Organic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Martin Lutz
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Marc-Etienne Moret
- Organic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands.
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4
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Landaeta VR, Horsley Downie TM, Wolf R. Low-Valent Transition Metalate Anions in Synthesis, Small Molecule Activation, and Catalysis. Chem Rev 2024; 124:1323-1463. [PMID: 38354371 PMCID: PMC10906008 DOI: 10.1021/acs.chemrev.3c00121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 10/09/2023] [Accepted: 10/09/2023] [Indexed: 02/16/2024]
Abstract
This review surveys the synthesis and reactivity of low-oxidation state metalate anions of the d-block elements, with an emphasis on contributions reported between 2006 and 2022. Although the field has a long and rich history, the chemistry of transition metalate anions has been greatly enhanced in the last 15 years by the application of advanced concepts in complex synthesis and ligand design. In recent years, the potential of highly reactive metalate complexes in the fields of small molecule activation and homogeneous catalysis has become increasingly evident. Consequently, exciting applications in small molecule activation have been developed, including in catalytic transformations. This article intends to guide the reader through the fascinating world of low-valent transition metalates. The first part of the review describes the synthesis and reactivity of d-block metalates stabilized by an assortment of ligand frameworks, including carbonyls, isocyanides, alkenes and polyarenes, phosphines and phosphorus heterocycles, amides, and redox-active nitrogen-based ligands. Thereby, the reader will be familiarized with the impact of different ligand types on the physical and chemical properties of metalates. In addition, ion-pairing interactions and metal-metal bonding may have a dramatic influence on metalate structures and reactivities. The complex ramifications of these effects are examined in a separate section. The second part of the review is devoted to the reactivity of the metalates toward small inorganic molecules such as H2, N2, CO, CO2, P4 and related species. It is shown that the use of highly electron-rich and reactive metalates in small molecule activation translates into impressive catalytic properties in the hydrogenation of organic molecules and the reduction of N2, CO, and CO2. The results discussed in this review illustrate that the potential of transition metalate anions is increasingly being tapped for challenging catalytic processes with relevance to organic synthesis and energy conversion. Therefore, it is hoped that this review will serve as a useful resource to inspire further developments in this dynamic research field.
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Affiliation(s)
| | | | - Robert Wolf
- University of Regensburg, Institute
of Inorganic Chemistry, 93040 Regensburg, Germany
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5
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Itazaki M, Nouichi K, Ookuma KI, Moriuchi T, Nakazawa H. Synthesis, Structure, and Reactivity of Molybdenum- and Tungsten-Indane Complexes with Tris(pyrazolyl)borate Ligand. Molecules 2024; 29:757. [PMID: 38398509 PMCID: PMC10893353 DOI: 10.3390/molecules29040757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 02/01/2024] [Accepted: 02/02/2024] [Indexed: 02/25/2024] Open
Abstract
The reaction of molybdenum complexes with a tris(pyrazolyl)borate ligand (Et4N[TpMo(CO)3] and Et4N[Tp*Mo(CO)3] (Tp = hydridotris(pyrazolyl)borate, Tp* = hydridotris(3,5-dimethylpyrazolyl)borate)) and InBr3 at a 1:1 molar ratio afforded molybdenum-indane complexes (Et4N[TpMo(CO)3(InBr3)] 1 and Et4N[Tp*Mo(CO)3(InBr3)] 2). In addition, tungsten-indane complexes, Et4N[TpW(CO)3(InBr3)] 3 and Et4N[Tp*W(CO)3(InBr3)] 4, were obtained by the reaction of corresponding tungsten complexes. Complex 4 reacted with H2O to form the hydrido complex Tp*W(CO)3H, in which the W-In bond was cleaved. On the other hand, 4 reacted with three equiv. of AgNO3 to form Et4N[Tp*W(CO)3{In(ONO2)}] 5, in which three substituents on the In were exchanged while retaining the W-In dative bond. Complexes 1-5 were fully characterized using NMR measurements and elemental analyses, and the structures of 1-5 and Et4N[Tp*W(CO)3] were determined via X-ray crystallography. These are the first examples of mononuclear molybdenum- and tungsten-indane complexes with Mo-In and W-In dative bonds.
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Affiliation(s)
- Masumi Itazaki
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan;
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan; (K.N.); (K.-i.O.)
| | - Kunihisa Nouichi
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan; (K.N.); (K.-i.O.)
| | - Ken-ichiro Ookuma
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan; (K.N.); (K.-i.O.)
| | - Toshiyuki Moriuchi
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan;
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan; (K.N.); (K.-i.O.)
| | - Hiroshi Nakazawa
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan;
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan; (K.N.); (K.-i.O.)
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6
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Woińska M, Hoser AA, Chodkiewicz ML, Woźniak K. Enhancing hydrogen positions in X-ray structures of transition metal hydride complexes with dynamic quantum crystallography. IUCRJ 2024; 11:45-56. [PMID: 37990870 PMCID: PMC10833390 DOI: 10.1107/s205225252300951x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 10/31/2023] [Indexed: 11/23/2023]
Abstract
Hirshfeld atom refinement (HAR) is a method which enables the user to obtain more accurate positions of hydrogen atoms bonded to light chemical elements using X-ray data. When data quality permits, this method can be extended to hydrogen-bonded transition metals (TMs), as in hydride complexes. However, addressing hydrogen thermal motions with HAR, particularly in TM hydrides, presents a challenge. At the same time, proper description of thermal vibrations can be vital for determining hydrogen positions correctly. In this study, we employ tools such as SHADE3 and Normal Mode Refinement (NoMoRe) to estimate anisotropic displacement parameters (ADPs) for hydrogen atoms during HAR and IAM refinements performed for seven structures of TM (Fe, Ni, Cr, Nb, Rh and Os) and metalloid (Sb) hydride complexes for which both the neutron and the X-ray structures have been determined. A direct comparison between neutron and HAR/SHADE3/NoMoRe ADPs reveals that the similarity between neutron hydrogen ADPs and those estimated with NoMoRe or SHADE3 is significantly higher than when hydrogen ADPs are refined with HAR. Regarding TM-H bond lengths, traditional HAR exhibits a slight advantage over the other methods. However, combining NoMoRe/SHADE3 with HAR results in a minor decrease in agreement with neutron TM-H bond lengths. For the Cr complex, for which high-resolution X-ray data were collected, an investigation of resolution-related effects was possible.
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Affiliation(s)
- Magdalena Woińska
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland
| | - Anna A. Hoser
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland
| | - Michał L. Chodkiewicz
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland
| | - Krzysztof Woźniak
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland
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7
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Hosseinmardi S, Scheurer A, Heinemann FW, Marigo N, Munz D, Meyer K. Closed Synthetic Cycle for Nickel-Based Dihydrogen Formation. Chemistry 2023; 29:e202302063. [PMID: 37615237 DOI: 10.1002/chem.202302063] [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: 06/29/2023] [Revised: 08/15/2023] [Accepted: 08/24/2023] [Indexed: 08/25/2023]
Abstract
Dihydrogen evolution was observed in a two-step protonation reaction starting from a Ni0 precursor with a tripodal N-heterocyclic carbene (NHC) ligand. Upon the first protonation, a NiII monohydride complex was formed, which was isolated and fully characterized. Subsequent protonation yields H2 via a transient intermediate (INT) and an isolable NiII acetonitrile complex. The latter can be reduced to regenerate its Ni0 precursor. The mechanism of H2 formation was investigated by using a deuterated acid and scrutinized by 1 H NMR spectroscopy and gas chromatography. Remarkably, the second protonation forms a rare nickel dihydrogen complex, which was detected and identified in solution and characterized by 1 H NMR spectroscopy. DFT-based computational analyses were employed to propose a reaction profile and a molecular structure of the Ni-H2 complex. Thus, a dihydrogen-evolving, closed-synthetic cycle is reported with a rare Ni-H2 species as a key intermediate.
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Affiliation(s)
- Soosan Hosseinmardi
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany
| | - Andreas Scheurer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany
| | - Frank W Heinemann
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany
| | - Nicola Marigo
- Inorganic Chemistry, Coordination Chemistry, Saarland University, Campus C4.1, 66123, Saarbrücken, Germany
| | - Dominik Munz
- Inorganic Chemistry, Coordination Chemistry, Saarland University, Campus C4.1, 66123, Saarbrücken, Germany
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany
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8
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Hastings CD, Huffman LSX, Tiwari CK, Betancourth JG, Brennessel WW, Barnett BR. Coordinatively Unsaturated Metallates of Cobalt(II), Nickel(II), and Zinc(II) Guarded by a Rigid and Narrow Void. Inorg Chem 2023; 62:11920-11931. [PMID: 37462947 PMCID: PMC10394664 DOI: 10.1021/acs.inorgchem.3c01335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Both natural enzymatic systems and synthetic porous material catalysts utilize well-defined and uniform channels to dictate reaction selectivities on the basis of size or shape. Mimicry of this design element in homogeneous systems is generally difficult owing to the flexibility inherent in most small molecular species. Herein, we report the synthesis of a tripodal ligand scaffold that orients a narrow and rigid cavity atop accessible metal coordination space. The permanent void is formed through a macrocyclization reaction whereby the 3,5-dihydroxyphenyl arms are covalently linked through methylene bridges. Deprotonative metallation leads to anionic and coordinatively unsaturated complexes of divalent cobalt, nickel, and zinc. An analogous series of trigonal monopyramidal complexes bearing a nonmacrocyclized variant of the tripodal ligand are also reported. Physical characterization of the coordination complexes has been carried out using multiple spectroscopic techniques (NMR, EPR, and UV-vis), cyclic voltammetry, and X-ray diffraction. Complexes of the macrocyclized [LOCH2O]3- ligand retain a rigid cavity upon metallation, with this cavity guarding the entrance to the open axial coordination site. Through a combination of spectroscopic and computational studies, it is shown that acetonitrile entry into the void is sterically precluded, disrupting anticipated coordination at the intracavity site.
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Affiliation(s)
- Christopher D Hastings
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Lucy S X Huffman
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Chandan Kumar Tiwari
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | | | - William W Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Brandon R Barnett
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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9
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Woińska M, Pawlędzio S, Chodkiewicz ML, Woźniak K. Hirshfeld Atom Refinement of Metal-Organic Complexes: Treatment of Hydrogen Atoms Bonded to Transition Metals. J Phys Chem A 2023; 127:3020-3035. [PMID: 36947670 PMCID: PMC10084459 DOI: 10.1021/acs.jpca.2c06998] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 03/04/2023] [Indexed: 03/24/2023]
Abstract
Hydrogen positions in hydrides play a key role in hydrogen storage materials and high-temperature superconductors. Our recently published study of five crystal structures of transition-metal-bound hydride complexes showed that using aspherical atomic scattering factors for Hirshfeld atom refinement (HAR) resulted in a systematic elongation of metal-hydrogen bonds compared to using spherical scattering factors with the Independent Atom Model (IAM). Even though only standard-resolution X-ray data was used, for the highest-quality data, we obtained excellent agreement between the X-ray and the neutron-derived bond lengths. We present an extended version of this study including 10 crystal structures of metal-organic complexes containing hydrogen atoms bonded to transition-metal atoms for which both X-ray and neutron data are available. The neutron structures were used as a benchmark, and the X-ray structures were refined by applying Hirshfeld atom refinement using various basis sets and DFT functionals in order to investigate the influence of the technical aspects on the length of metal-hydrogen bonds. The result of including relativistic effects in the Hamiltonian and using a cluster of multipoles simulating interactions with a crystal environment during wave function calculations was examined. The effect of the data quality on the final result was also evaluated. The study confirms that a high quality of experimental data is the key factor allowing us to obtain significant improvement in transition metal (TM)-hydrogen bond lengths from HAR in comparison with the IAM. Individual adjustments and better choices of the basis set can improve hydrogen positions. Average differences between TM-H bond lengths obtained with various DFT functionals upon including relativistic effects or between double-ζ and triple-ζ basis sets were not statistically significant. However, if all bonds formed by H atoms were considered, significant differences caused by different refinement strategies were observed. Finally, we examined the refinement of atomic thermal motions. Anisotropic refinement of hydrogen thermal motions with HAR was feasible only in some cases, and isotropically refined hydrogen thermal motions were in similar agreement with neutron values whether obtained with HAR or with the IAM.
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Affiliation(s)
- Magdalena Woińska
- Biological and Chemical Research
Centre, Chemistry Department, University
of Warsaw, Żwirki i Wigury 101, 02-089 Warszawa, Poland
| | - Sylwia Pawlędzio
- Biological and Chemical Research
Centre, Chemistry Department, University
of Warsaw, Żwirki i Wigury 101, 02-089 Warszawa, Poland
| | - Michał L. Chodkiewicz
- Biological and Chemical Research
Centre, Chemistry Department, University
of Warsaw, Żwirki i Wigury 101, 02-089 Warszawa, Poland
| | - Krzysztof Woźniak
- Biological and Chemical Research
Centre, Chemistry Department, University
of Warsaw, Żwirki i Wigury 101, 02-089 Warszawa, Poland
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10
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Garçon M, Phanopoulos A, White AJP, Crimmin MR. Reversible Dihydrogen Activation and Catalytic H/D Exchange with Group 10 Heterometallic Complexes. Angew Chem Int Ed Engl 2023; 62:e202213001. [PMID: 36350647 PMCID: PMC10107683 DOI: 10.1002/anie.202213001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Indexed: 11/10/2022]
Abstract
Reaction of a hexagonal planar palladium complex featuring a [PdMg3 H3 ] core with H2 is reversible and leads to the formation of a new [PdMg2 H4 ] tetrahydride species alongside an equivalent of a magnesium hydride co-product [MgH]. While the reversibility of this process prevented isolation of [PdMg2 H4 ], analogous [PtMg2 H4 ] and [PtZn2 H4 ] complexes could be isolated and characterised through independent syntheses. Computational analysis (DFT, AIM, NCIPlot) of the bonding in a series of heterometallic tetrahydride compounds (Ni-Pt; Mg and Zn) suggests that these complexes are best described as square planar with marginal metal-metal interactions; the strength of which increases slightly as group 10 is descended and increases from Mg to Zn. DFT calculations support a mechanism for H2 activation involving a ligand-assisted oxidative addition to Pd. These findings were exploited to develop a catalytic protocol for H/D exchange into magnesium hydride and zinc hydride bonds.
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Affiliation(s)
- Martí Garçon
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, London, W12 0BZ, UK
| | - Andreas Phanopoulos
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, London, W12 0BZ, UK
| | - Andrew J P White
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, London, W12 0BZ, UK
| | - Mark R Crimmin
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, London, W12 0BZ, UK
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11
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Moore JT, Dorantes MJ, Pengmei Z, Schwartz TM, Schaffner J, Apps SL, Gaggioli CA, Das U, Gagliardi L, Blank DA, Lu CC. Light-Driven Hydrodefluorination of Electron-Rich Aryl Fluorides by an Anionic Rhodium-Gallium Photoredox Catalyst. Angew Chem Int Ed Engl 2022; 61:e202205575. [PMID: 36017770 PMCID: PMC9826370 DOI: 10.1002/anie.202205575] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Indexed: 01/11/2023]
Abstract
An anionic Rh-Ga complex catalyzed the hydrodefluorination of challenging C-F bonds in electron-rich aryl fluorides and trifluoromethylarenes when irradiated with violet light in the presence of H2 , a stoichiometric alkoxide base, and a crown-ether additive. Based on theoretical calculations, the lowest unoccupied molecular orbital (LUMO), which is delocalized across both the Rh and Ga atoms, becomes singly occupied upon excitation, thereby poising the Rh-Ga complex for photoinduced single-electron transfer (SET). Stoichiometric and control reactions support that the C-F activation is mediated by the excited anionic Rh-Ga complex. After SET, the proposed neutral Rh0 intermediate was detected by EPR spectroscopy, which matched the spectrum of an independently synthesized sample. Deuterium-labeling studies corroborate the generation of aryl radicals during catalysis and their subsequent hydrogen-atom abstraction from the THF solvent to generate the hydrodefluorinated arene products. Altogether, the combined experimental and theoretical data support an unconventional bimetallic excitation that achieves the activation of strong C-F bonds and uses H2 and base as the terminal reductant.
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Affiliation(s)
- James T. Moore
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA
| | - Michael J. Dorantes
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA
| | - Zihan Pengmei
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA
| | - Timothy M. Schwartz
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA,Institut für Anorganische ChemieUniversität BonnGerhard-Domagk-Str. 1Bonn53121Deutschland
| | - Jacob Schaffner
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA
| | - Samantha L. Apps
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA
| | - Carlo A. Gaggioli
- Department of ChemistryUniversity of Chicago5735 S Ellis Ave.ChicagoIllinois60637USA
| | - Ujjal Das
- Institut für Anorganische ChemieUniversität BonnGerhard-Domagk-Str. 1Bonn53121Deutschland
| | - Laura Gagliardi
- Department of ChemistryUniversity of Chicago5735 S Ellis Ave.ChicagoIllinois60637USA
| | - David A. Blank
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA
| | - Connie C. Lu
- Department of ChemistryUniversity of Minnesota207 Pleasant Street SEMinneapolisMinnesota55455-0431USA,Institut für Anorganische ChemieUniversität BonnGerhard-Domagk-Str. 1Bonn53121Deutschland
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12
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Komuro T, Nakajima Y, Takaya J, Hashimoto H. Recent progress in transition metal complexes supported by multidentate ligands featuring group 13 and 14 elements as coordinating atoms. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Paskaruk K, Emslie DJH, Britten JF. Coordination chemistry and structural rearrangements of the Me 2PCH 2AlMe 2 ambiphilic ligand. Dalton Trans 2022; 51:15040-15048. [PMID: 36112126 DOI: 10.1039/d2dt02519a] [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
Reaction of 2 equivalents of (Me2PCH2AlMe2)2 with [{RhCl(cod)}2] (cod = 1,5-cyclooctadiene) afforded [{κ2P,P-(Me3Al)ClMeAl(CH2PMe2)2}Rh(cod)] (1), which features a κ2-coordinated bis(phosphino)aluminate anion. In compound 1, an Al-Cl substituent bridges to a molecule of AlMe3, which could be removed in vacuo to provide [{κ2P,P-ClMeAl(CH2PMe2)2}Rh(cod)] (2). By contrast, reaction of 1 equiv. of (Me2PCH2AlMe2)2 with [{RhCl(cod)}2] yielded [Rh(cod)(μ-Cl)(Me2PCH2AlMe2)] (3) as the major product, where the phosphine donor of an intact Me2PCH2AlMe2 ligand is coordinated to rhodium and a chloride ligand bridges between Rh and Al. [Rh(cod)(μ-Cl)(Me2PCH2AlClMe)] (3A) and 2 were also formed as minor products. The aforementioned reactions were carried out in benzene or toluene, whereas the 1 : 1 reaction of (Me2PCH2AlMe2)2 with [{RhCl(cod)}2] in THF afforded [{Rh(μ-CH2PMe2)(cod)}2] (4). Reactions of (Me2PCH2AlMe2)2 with iridium(I), gold(I) and platinum(II) precursors were also explored. A 1 : 1 reaction of (Me2PCH2AlMe2)2 with [{IrCl(cod)}2] afforded [{κ2P,P-Cl2Al(CH2PMe2)2}Ir(cod)] (5) as one of two major phosphine-containing products; unlike 3, this compound features two chlorine substituents on aluminium. For comparison, the rhodium analogue of 5, [{κ2P,P-Cl2Al(CH2PMe2)2}Rh(cod)] (6), was also synthesized via the 1 : 1 reaction of {ClAl(CH2PMe2)2}2 with [{RhCl(cod)}2]. Reactions of (Me2PCH2AlMe2)2 with [AuCl(CO)] or [PtCl2(cod)] also resulted in chloride-methyl group exchange between the transition metal and aluminium. However, these reactions generated free (Me2PCH2AlClMe)2 accompanied by gold and ethane, or [PtMe2(cod)], respectively. Reaction of 1.5 equivalents of (Me2PCH2AlMe2)2 with [PtMe2(cod)] at 75 °C afforded zwitterionic [(PtMe{μ-κ1P:κ2P,P-MeAl(CH2PMe2)3})2] (7) which features two tris(phosphino)aluminate anions bridging between PtMe units. Compounds 1-2, 3/3A, 4-7 and (Me2PCH2AlClMe)2 were crystallographically characterized.
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Affiliation(s)
- Katarina Paskaruk
- Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1, Canada.
| | - David J H Emslie
- Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1, Canada.
| | - James F Britten
- Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1, Canada.
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14
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Moore JT, Dorantes MJ, Pengmei Z, Schwartz TM, Schaffner J, Apps SL, Gaggioli CA, Das U, Gagliardi L, Blank DA, Lu CC. Light‐Driven Hydrodefluorination of Electron‐Rich Aryl Fluorides by an Anionic Rhodium‐Gallium Photoredox Catalyst. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- James T. Moore
- University of Minnesota College of Science and Engineering Chemistry UNITED STATES
| | - Michael J. Dorantes
- University of Minnesota College of Science and Engineering Chemistry UNITED STATES
| | - Zihan Pengmei
- University of Chicago Department of Chemistry Chemistry UNITED STATES
| | - Timothy M. Schwartz
- University of Bonn: Rheinische Friedrich-Wilhelms-Universitat Bonn Inorganic Chemistry GERMANY
| | - Jacob Schaffner
- University of Minnesota College of Science and Engineering Chemistry UNITED STATES
| | - Samantha L. Apps
- University of Minnesota College of Science and Engineering Chemistry UNITED STATES
| | - Carlo A. Gaggioli
- University of Chicago Department of Chemistry Chemistry UNITED STATES
| | - Ujjal Das
- University of Bonn: Rheinische Friedrich-Wilhelms-Universitat Bonn Inorganic Chemistry GERMANY
| | - Laura Gagliardi
- University of Chicago Department of Chemistry Chemistry UNITED STATES
| | - David A. Blank
- University of Minnesota College of Science and Engineering Chemistry UNITED STATES
| | - Connie C. Lu
- University of Minnesota College of Science and Engineering Chemistry Gerhard-Domagk-Straße 1 53121 Bonn GERMANY
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15
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Prat JR, Cammarota RC, Graziano BJ, Moore JT, Lu CC. Toggling the Z-type interaction off-on in nickel-boron dihydrogen and anionic hydride complexes. Chem Commun (Camb) 2022; 58:8798-8801. [PMID: 35838123 DOI: 10.1039/d2cc03219h] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Completing a series of nickel-group 13 complexes, a coordinatively unsaturated nickel-boron complex and its derivatives with a H2, N2, or hydride ligand were synthesized and characterized. The toggling "on" of a Ni(0)-B(III) inverse-dative bond enabled the stabilization of a nickel-bound anionic hydride with a remarkably low thermodynamic hydricity of kcal mol-1 in THF. The flexible topology of the boron metalloligand confers both favorable hydrogen binding affinity and strong hydride donicity, albeit at the cost of high H2 basicity during deprotonation to form the hydride.
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Affiliation(s)
- Jacob R Prat
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
| | - Ryan C Cammarota
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
| | - Brendan J Graziano
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
| | - James T Moore
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
| | - Connie C Lu
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA.,Institute of Inorganic Chemistry, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany.
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16
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Li R, Barel N, Subramaniyan V, Cohen O, Tibika F, Tulchinsky Y. Sulfonium cations as versatile strongly π-acidic ligands. Chem Sci 2022; 13:4770-4778. [PMID: 35655889 PMCID: PMC9067576 DOI: 10.1039/d2sc00588c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 03/14/2022] [Indexed: 01/31/2023] Open
Abstract
More than a century old, sulfonium cations are still intriguing species in the landscape of organic chemistry. On one hand they have found broad applications in organic synthesis and materials science, but on the other hand, while isoelectronic to the ubiquitous tertiary phosphine ligands, their own coordination chemistry has been neglected for the last three decades. Here we report the synthesis and full characterization of the first Rh(i) and Pt(ii) complexes of sulfonium. Moreover, for the first time, coordination of an aromatic sulfonium has been established. A thorough computational analysis of the exceptionally short S-Rh bonds obtained attests to the strongly π-accepting nature of sulfonium cations and places them among the best π-acceptor ligands available today. Our calculations also show that embedding within a pincer framework enhances their π-acidity even further. Therefore, in addition to the stability and modularity that these frameworks offer, our pincer complexes might open the way for sulfonium cations to become powerful tools in π-acid catalysis.
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Affiliation(s)
- Ruiping Li
- Institute of Chemistry, The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | - Nitsan Barel
- Institute of Chemistry, The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | | | - Orit Cohen
- Institute of Chemistry, The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | - Françoise Tibika
- Institute of Chemistry, The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | - Yuri Tulchinsky
- Institute of Chemistry, The Hebrew University of Jerusalem Jerusalem 9190401 Israel
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17
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Uchida K, Kishimoto N, Noro SI, Iguchi H, Takaishi S. Reversible hydrogen adsorption at room temperature using a molybdenum-dihydrogen complex in the solid state. Dalton Trans 2021; 50:12630-12634. [PMID: 34545876 DOI: 10.1039/d1dt01404h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Reversible H2 storage under mild conditions is one of the most important targets in the field of materials chemistry. Dihydrogen complexes are attractive materials for this target because they possess moderate adsorption enthalpy as well as adsorption without cleavage of the H-H bond. In spite of these advantages, H2 adsorption studies of dihydrogen complexes in the solid state are scarce. We herein present H2 adsorption properties of the 16-electron precursor complex ([Mo(PCy3)2(CO)3]) in the solid state synthesized by two procedures. One is the direct synthesis under an Ar atmosphere (1), and the other is removal of the N2-adduct under vacuum (2). 2 showed ideal Langmuir type reversible ad/desorption of H2 above room temperature, whereas 1 showed irreversible adsorption. The adsorption enthalpy of 2 was larger than that in THF solution. Using DFT calculation, this difference was explained by the absence of the agostic interaction in the solid state.
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Affiliation(s)
- Kaiji Uchida
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
| | - Naoki Kishimoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
| | - Shin-Ichiro Noro
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Hiroaki Iguchi
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
| | - Shinya Takaishi
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
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18
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Barnett BR, Evans HA, Su GM, Jiang HZH, Chakraborty R, Banyeretse D, Hartman TJ, Martinez MB, Trump BA, Tarver JD, Dods MN, Funke LM, Börgel J, Reimer JA, Drisdell WS, Hurst KE, Gennett T, FitzGerald SA, Brown CM, Head-Gordon M, Long JR. Observation of an Intermediate to H 2 Binding in a Metal-Organic Framework. J Am Chem Soc 2021; 143:14884-14894. [PMID: 34463495 DOI: 10.1021/jacs.1c07223] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Coordinatively unsaturated metal sites within certain zeolites and metal-organic frameworks can strongly adsorb a wide array of substrates. While many classical examples involve electron-poor metal cations that interact with adsorbates largely through physical interactions, unsaturated electron-rich metal centers housed within porous frameworks can often chemisorb guests amenable to redox activity or covalent bond formation. Despite the promise that materials bearing such sites hold in addressing myriad challenges in gas separations and storage, very few studies have directly interrogated mechanisms of chemisorption at open metal sites within porous frameworks. Here, we show that nondissociative chemisorption of H2 at the trigonal pyramidal Cu+ sites in the metal-organic framework CuI-MFU-4l occurs via the intermediacy of a metastable physisorbed precursor species. In situ powder neutron diffraction experiments enable crystallographic characterization of this intermediate, the first time that this has been accomplished for any material. Evidence for a precursor intermediate is also afforded from temperature-programmed desorption and density functional theory calculations. The activation barrier separating the precursor species from the chemisorbed state is shown to correlate with a change in the Cu+ coordination environment that enhances π-backbonding with H2. Ultimately, these findings demonstrate that adsorption at framework metal sites does not always follow a concerted pathway and underscore the importance of probing kinetics in the design of next-generation adsorbents.
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Affiliation(s)
- Brandon R Barnett
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Hayden A Evans
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Gregory M Su
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Henry Z H Jiang
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Romit Chakraborty
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Didier Banyeretse
- Department of Physics, Oberlin College, Oberlin, Ohio 44074, United States
| | - Tyler J Hartman
- Department of Physics, Oberlin College, Oberlin, Ohio 44074, United States
| | - Madison B Martinez
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Benjamin A Trump
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jacob D Tarver
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Matthew N Dods
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States
| | - Lena M Funke
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.,Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States
| | - Jonas Börgel
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Jeffrey A Reimer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States
| | - Walter S Drisdell
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Katherine E Hurst
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Thomas Gennett
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.,Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | | | - Craig M Brown
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.,Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Martin Head-Gordon
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jeffrey R Long
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States
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19
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Ghosh B, Fantuzzi F, Phukan AK. Understanding, Modulating, and Leveraging Transannular M → Z Interactions. Inorg Chem 2021; 60:12790-12800. [PMID: 34424687 DOI: 10.1021/acs.inorgchem.1c00977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Density functional theory calculations have been performed on metallatranes featuring a group 13 elements at the bridgehead position to understand the factors that influence the nature of the M···Z (M = Fe, Co, Ni; Z = Al, Ga, In) interaction present in these complexes and the resultant reactivity at the metal center. The strength of the M···Z interaction increases with the increase in the size and polarizability of the bridgehead group 13 elements. The calculated reaction free energies (ΔG° values) for binding of different Lewis bases to the metallatranes are found to be significantly more exergonic for the larger In(III) ions. Quantum theory of atoms in molecules calculations reveal the covalent nature of the M···Z interactions, while the EDA-NOCV analysis indicates the strong binding ability of these metallatranes not only to different σ-donor and π-acceptor ligands but also to relatively inert species, such as N2.
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Affiliation(s)
- Bijoy Ghosh
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India
| | - Felipe Fantuzzi
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ashwini K Phukan
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India
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20
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Persaud RR, Fang Z, Zall CM, Appel AM, Dixon DA. Computational Study of Triphosphine-Ligated Cu(I) Catalysts for Hydrogenation of CO 2 to Formate. J Phys Chem A 2021; 125:6600-6610. [PMID: 34297558 DOI: 10.1021/acs.jpca.1c04050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The catalyzed hydrogenation of CO2 to formate via a triphosphine-ligated Cu(I) was studied computationally at the density functional theory level in the presence of a self-consistent reaction field. Of the four functionals benchmarked, M06 was generally in the best agreement with the available experimentally estimated values. Two bases, DBU and TBD, were studied in the context of two proposed mechanisms in the MeCN solvent. Activation of H2 was explored by using LCu(DBU)+ to form LCuH. Dissociation of a ligand arm results in higher barriers to form the key hydride complex, LCuH. The preferred mechanism passes through a transition state, where the H2 has one H atom interacting with the copper center and the other H atom interacting with the N atom of the base, similar to H2 insertion into a frustrated Lewis pair. There is no significant difference between the choice of a base, DBU or TBD, with respect to the proposed mechanisms. We propose that the experimentally observed differences between DBU and TBD reactivities for this mechanism are due to off-pathway changes.
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Affiliation(s)
- Rudradatt R Persaud
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Zongtang Fang
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Christopher M Zall
- Department of Chemistry, Sam Houston State University, 1003 Bowers Boulevard, Huntsville, Texas 77341, United States
| | - Aaron M Appel
- Pacific Northwest National Laboratory, P.O. Box 999, MS K2-57, Richland, Washington 99352, United States
| | - David A Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
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21
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Charles RM, Brewster TP. H 2 and carbon-heteroatom bond activation mediated by polarized heterobimetallic complexes. Coord Chem Rev 2021; 433:213765. [PMID: 35418712 PMCID: PMC9004596 DOI: 10.1016/j.ccr.2020.213765] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The field of heterobimetallic chemistry has rapidly expanded over the last decade. In addition to their interesting structural features, heterobimetallic structures have been found to facilitate a range of stoichiometric bond activations and catalytic processes. The accompanying review summarizes advances in this area since January of 2010. The review encompasses well-characterized heterobimetallic complexes, with a particular focus on mechanistic details surrounding their reactivity applications.
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Affiliation(s)
- R Malcolm Charles
- Department of Chemistry, The University of Memphis, 3744 Walker Ave., Smith Chemistry Building, Memphis, TN 38152, United States
| | - Timothy P Brewster
- Department of Chemistry, The University of Memphis, 3744 Walker Ave., Smith Chemistry Building, Memphis, TN 38152, United States
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22
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Wang Q, Brooks SH, Liu T, Tomson NC. Tuning metal-metal interactions for cooperative small molecule activation. Chem Commun (Camb) 2021; 57:2839-2853. [PMID: 33624638 PMCID: PMC8274379 DOI: 10.1039/d0cc07721f] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cluster complexes have attracted interest for decades due to their promise of drawing analogies to metallic surfaces and metalloenzyme active sites, but only recently have chemists started to develop ligand scaffolds that are specifically designed to support multinuclear transition metal cores. Such ligands not only hold multiple metal centers in close proximity but also allow for fine-tuning of their electronic structures and surrounding steric environments. This Feature Article highlights ligand designs that allow for cooperative small molecule activation at cluster complexes, with a particular focus on complexes that contain metal-metal bonds. Two useful ligand-design elements have emerged from this work: a degree of geometric flexibility, which allows for novel small molecule activation modes, and the use of redox-active ligands to provide electronic flexibility to the cluster core. The authors have incorporated these factors into a unique class of dinucleating macrocycles (nPDI2). Redox-active fragments in nPDI2 mimic the weak-overlap covalent bonding that is characteristic of M-M interactions, and aliphatic linkers in the ligand backbone provide geometric flexibility, allowing for interconversion between a range of geometries as the dinuclear core responds to the requirements of various small molecule substrates. The union of these design elements appears to be a powerful combination for analogizing critical aspects of heterogeneous and metalloenzyme catalysts.
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Affiliation(s)
- Qiuran Wang
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.
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23
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Lücke MP, Yao S, Driess M. Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst. Chem Sci 2021; 12:2909-2915. [PMID: 34164057 PMCID: PMC8179395 DOI: 10.1039/d0sc06471h] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/04/2021] [Indexed: 11/21/2022] Open
Abstract
The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2 (cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecular η 2-arene coordination of Ni, [E(Terp)E]Ni(η 2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2 activation and H atom transfer, [SiII(Terp)SiII]Ni(η 2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2 pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η 2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h-1) could be realised.
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Affiliation(s)
- Marcel-Philip Lücke
- Department of Chemistry: Metalorganics and Inorganic Materials Technische Universität Berlin Strasse des 17. Juni 115, Sekr. C2 D-10623 Berlin Germany
| | - Shenglai Yao
- Department of Chemistry: Metalorganics and Inorganic Materials Technische Universität Berlin Strasse des 17. Juni 115, Sekr. C2 D-10623 Berlin Germany
| | - Matthias Driess
- Department of Chemistry: Metalorganics and Inorganic Materials Technische Universität Berlin Strasse des 17. Juni 115, Sekr. C2 D-10623 Berlin Germany
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24
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Ríos P, Borge J, Fernández de Córdova F, Sciortino G, Lledós A, Rodríguez A. Ambiphilic boryl groups in a neutral Ni(ii) complex: a new activation mode of H 2. Chem Sci 2020; 12:2540-2548. [PMID: 34164022 PMCID: PMC8179274 DOI: 10.1039/d0sc06014c] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/21/2020] [Indexed: 12/18/2022] Open
Abstract
The concept of metal-ligand cooperation opens new avenues for the design of catalytic systems that may offer alternative reactivity patterns to the existing ones. Investigations of this concept with ligands bearing a boron center in their skeleton established mechanistic pathways for the activation of small molecules in which the boron atom usually performs as an electrophile. Here, we show how this electrophilic behavior can be modified by the ligand trans to the boron center, evincing its ambiphilic nature. Treatment of diphosphinoboryl (PBP) nickel-methyl complex 1 with bis(catecholato)diboron (B2Cat2) allows for the synthesis of nickel(ii) bis-boryl complex 3 that promotes the clean and reversible heterolytic cleavage of dihydrogen leading to the formation of dihydroborate nickel complex 4. Density functional theory analysis of this reaction revealed that the heterolytic activation of H2 is facilitated by the cooperation of both boryl moieties and the metal atom in a concerted mechanism that involves a Ni(ii)/Ni(0)/Ni(ii) process. Contrary to 1, the boron atom from the PBP ligand in 3 behaves as a nucleophile, accepting a formally protic hydrogen, whereas the catecholboryl moiety acts as an electrophile, receiving the attack from the hydride-like fragment. This manifests the dramatic change in the electronic properties of a ligand by tuning the substituent trans to it and constitutes an unprecedented cooperative mechanism that involves two boryl ligands in the same molecule operating differently, one as a Lewis acid and the other one as a Lewis base, in cooperation with the metal. In addition, reactivity towards different nucleophiles such as amines or ammonia confirmed the electrophilic nature of the Bcat moiety, allowing the formation of aminoboranes.
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Affiliation(s)
- Pablo Ríos
- Instituto de Investigaciones Químicas, Departamento de Química Inorgánica, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Centro de Innovación en Química Avanzada (ORFEO-CINQA) C/Américo Vespucio 49 41092 Sevilla Spain
| | - Javier Borge
- Departamento de Química Física y Analítica, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Oviedo C/Julián Clavería 8 33006 Oviedo Spain
| | - Francisco Fernández de Córdova
- Instituto de Investigaciones Químicas, Departamento de Química Inorgánica, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Centro de Innovación en Química Avanzada (ORFEO-CINQA) C/Américo Vespucio 49 41092 Sevilla Spain
| | - Giuseppe Sciortino
- Departament de Química, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Autònoma de Barcelona Campus UAB 08193 Cerdanyola del Vallès Spain
| | - Agustí Lledós
- Departament de Química, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Autònoma de Barcelona Campus UAB 08193 Cerdanyola del Vallès Spain
| | - Amor Rodríguez
- Instituto de Investigaciones Químicas, Departamento de Química Inorgánica, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Centro de Innovación en Química Avanzada (ORFEO-CINQA) C/Américo Vespucio 49 41092 Sevilla Spain
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25
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Mei L, Veleta JM, Bloch J, Goodman HJ, Pierce-Navarro D, Villalobos A, Gianetti TL. Tunable carbocation-based redox active ambiphilic ligands: synthesis, coordination and characterization. Dalton Trans 2020; 49:16095-16105. [PMID: 32186563 DOI: 10.1039/d0dt00419g] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The synthesis of novel redox active ambiphilic ligands L1-L3 and their coordination chemistry to first-row late transition metal halides (M = Co and Ni) is reported. The heterocyclic carbocation scaffolds act as Lewis acid moieties while the pyridine anchor acts as the coordinating Lewis base. The high synthetic tunability of this ligand scaffold allows for control of its rigidity and electronic properties. Anion exchange and coordination of a chloride anion to the metal center was observed resulting in the formation of [MCl3]- metallate. Upon coordination to the pyridine anchor, the metallate centers adopt a canonical tetrahedral geometry, resulting in an overall neutral complex best described as a zwitterionic metallate trichloride bound to a cationic ligand. Characterization techniques including single crystal X-ray diffraction, cyclic voltammetry, and UV-Vis absorption spectroscopy were employed to better understand the structural and chemical properties of the ligands and metal complexes. A possible weak interaction between one of the chlorides and the carbenium moiety in the ligand is observed in crystals of both of the Co(ii) and Ni(ii) complexes with ligand L1. Density functional theory (DFT) calculations support that this electrostatic interaction for complexes 2a and 2b exists only in the solid state.
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Affiliation(s)
- Liangyong Mei
- University of Arizona, Department of Chemistry and Biochemistry, Tucson, AZ, USA.
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26
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Deegan MM, Hannoun KI, Peters JC. Dihydrogen Adduct (Co–H
2
) Complexes Displaying H‐Atom and Hydride Transfer. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202009814] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Meaghan M. Deegan
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Kareem I. Hannoun
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Jonas C. Peters
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
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27
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Deegan MM, Hannoun KI, Peters JC. Dihydrogen Adduct (Co–H
2
) Complexes Displaying H‐Atom and Hydride Transfer. Angew Chem Int Ed Engl 2020; 59:22631-22637. [DOI: 10.1002/anie.202009814] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Meaghan M. Deegan
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Kareem I. Hannoun
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Jonas C. Peters
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
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28
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Raghavan A, Yuan F, Ren T. Drastic Tuning of the Electronic Structures of Diruthenium Aryl Complexes by Isoelectronic Axial Ligands. Inorg Chem 2020; 59:8663-8666. [PMID: 32568533 DOI: 10.1021/acs.inorgchem.0c01755] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reported herein is the use of aryls as axial ligands to manipulate reactivity at the distal metal site through metal-metal-ligand interactions in diruthenium paddlewheel complexes. The vacant ruthenium site in Ru2(ap)4(Ar) (1; ap = 2-anilinopyridinate and Ar = C6H4-4-NMe2), thus rendered reactive, is able to bind a series of isoelectronic ligands to afford three complexes of the form (Y)[Ru2(ap)4](Ar) [Y = CN- (2), HC≡C- (3), CO (4)], each of which exhibits a distinct electronic structure. While reactions with anionic ligands subsequently result in oxidation of the diruthenium core from Ru2(II,III) to Ru2(III,III), the reaction with CO yields a rare example of a Ru2(II,III)-COaxial adduct. The latter reaction is particularly interesting in its completely reversible change of the ground state from S = 3/2 in 1 to S = 1/2 in 4, the first of its kind seen in Ru2(II,III) species. In general, this work sheds light on the modulation of the electronic structure of diruthenium paddlewheel complexes using distinct coordination environments around each of the ruthenium centers.
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Affiliation(s)
- Adharsh Raghavan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Fang Yuan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tong Ren
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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29
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McNeill AS, Zhan CG, Appel AM, Stanbury DM, Dixon DA. The H•/H– Redox Couple and Absolute Hydration Energy of H–. J Phys Chem A 2020; 124:6084-6095. [DOI: 10.1021/acs.jpca.0c03833] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ashley S. McNeill
- Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Chang-Guo Zhan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Aaron M. Appel
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - David M. Stanbury
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - David A. Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
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30
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Eaton MC, Knight BJ, Catalano VJ, Murray LJ. Evaluating Metal Ion Identity on Catalytic Silylation of Dinitrogen Using a Series of Trimetallic Complexes. Eur J Inorg Chem 2020; 2020:1519-1524. [PMID: 33071629 DOI: 10.1002/ejic.201901335] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We report catalytic silylation of dinitrogen to tris(trimethylsilyl)amine by a series of trinuclear first row transition metal complexes (M = Cr, Mn, Fe, Co, Ni) housed in our tris(β-diketiminate) cyclophane (L 3- ). Yields are expectedly dependent on metal ion type ranging from 14 to 199 equiv NH4 +/complex after protonolysis for the Mn to Co congeners, respectively. For the series of complexes, the number of turnovers trend observed is Co > Fe > Cr > Ni > Mn, consistent with prior reports of greater efficacy of Co over Fe in other ligand systems for this reaction.
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Affiliation(s)
- Mary C Eaton
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, FL 32611-7200 (USA)
| | - Brian J Knight
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, FL 32611-7200 (USA)
| | | | - Leslie J Murray
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, FL 32611-7200 (USA)
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31
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Ramirez BL, Lu CC. Rare-Earth Supported Nickel Catalysts for Alkyne Semihydrogenation: Chemo- and Regioselectivity Impacted by the Lewis Acidity and Size of the Support. J Am Chem Soc 2020; 142:5396-5407. [DOI: 10.1021/jacs.0c00905] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Bianca L. Ramirez
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Connie C. Lu
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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32
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Vollmer MV, Ye J, Linehan JC, Graziano BJ, Preston A, Wiedner ES, Lu CC. Cobalt-Group 13 Complexes Catalyze CO2 Hydrogenation via a Co(−I)/Co(I) Redox Cycle. ACS Catal 2020. [DOI: 10.1021/acscatal.9b03534] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Matthew V. Vollmer
- Department of Chemistry, University of Minnesota−Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Jingyun Ye
- Department of Chemistry, University of Minnesota−Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
- Supercomputing Institute, and Chemical Theory Center, University of Minnesota−Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - John C. Linehan
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, MS K2-57, Richland, Washington 99352, United States
| | - Brendan J. Graziano
- Department of Chemistry, University of Minnesota−Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Andrew Preston
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, MS K2-57, Richland, Washington 99352, United States
| | - Eric S. Wiedner
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, MS K2-57, Richland, Washington 99352, United States
| | - Connie C. Lu
- Department of Chemistry, University of Minnesota−Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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33
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Lai Q, Cosio MN, Ozerov OV. Ni complexes of an alane/tris(phosphine) ligand built around a strongly Lewis acidic tris(N-pyrrolyl)aluminum. Chem Commun (Camb) 2020; 56:14845-14848. [DOI: 10.1039/d0cc05452f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Syntheses of a new tripodal alane/tris(phosphine) ligand (AlP3) based on 2-(diisopropylphosphino)pyrrole, and AlP3-supported Ni complexes are reported.
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Affiliation(s)
- Qingheng Lai
- Department of Chemistry
- Texas A&M University
- College Station
- USA
| | - Mario N. Cosio
- Department of Chemistry
- Texas A&M University
- College Station
- USA
| | - Oleg V. Ozerov
- Department of Chemistry
- Texas A&M University
- College Station
- USA
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34
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Arnett CH, Kaiser JT, Agapie T. Remote Ligand Modifications Tune Electronic Distribution and Reactivity in Site-Differentiated, High-Spin Iron Clusters: Flipping Scaling Relationships. Inorg Chem 2019; 58:15971-15982. [PMID: 31738534 DOI: 10.1021/acs.inorgchem.9b02470] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the synthesis, characterization, and reactivity of [LFe3O(RArIm)3Fe][OTf]2, the first Hammett series of a site-differentiated cluster. The cluster reduction potentials and CO stretching frequencies shift as expected on the basis of the electronic properties of the ligand: electron-donating substituents result in more reducing clusters and weaker C-O bonds. However, unusual trends in the energetics of their two sequential CO binding events with the substituent σp parameters are observed. Specifically, introduction of electron-donating substituents suppresses the first CO binding event (ΔΔH by as much as 7.9 kcal mol-1) but enhances the second (ΔΔH by as much as 1.9 kcal mol-1). X-ray crystallography, including multiple-wavelength anomalous diffraction, Mössbauer spectroscopy, and SQUID magnetometry, reveal that these substituent effects result from changes in the energetic penalty associated with electronic redistribution within the cluster, which occurs during the CO binding event.
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Affiliation(s)
- Charles H Arnett
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Jens T Kaiser
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
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