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Chambenahalli R, Bhargav RM, McCabe KN, Andrews AP, Ritter F, Okuda J, Maron L, Venugopal A. Cationic Zinc Hydride Catalyzed Carbon Dioxide Reduction to Formate: Deciphering Elementary Reactions, Isolation of Intermediates, and Computational Investigations. Chemistry 2021; 27:7391-7401. [PMID: 33459452 DOI: 10.1002/chem.202005392] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/11/2021] [Indexed: 01/06/2023]
Abstract
Zinc has been an element of choice for carbon dioxide reduction in recent years. Zinc compounds have been showcased as catalysts for carbon dioxide hydrosilylation and hydroboration. The extent of carbon dioxide reduction can depend on various factors, including electrophilicity at the zinc center and the denticity of the ancillary ligands. In a few cases, the addition of Lewis acids to zinc hydride catalysts markedly influences carbon dioxide reduction. These factors have been investigated by exploring elementary reactions of carbon dioxide hydrosilylation and hydroboration by using cationic zinc hydrides bearing tetradentate tris[2-(dimethylamino)ethyl]amine and tridentate N,N,N',N'',N''-pentamethyldiethylenetriamine in the presence of triphenylborane and tris(pentafluorophenyl)borane.
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Affiliation(s)
- Raju Chambenahalli
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, 695551, India
| | - R M Bhargav
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, 695551, India
| | - Karl N McCabe
- LPCNO, UMR 5215, Université de Toulouse-CNRS, INSA, UPS, 31077, Toulouse, France
| | - Alex P Andrews
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, 695551, India
| | - Florian Ritter
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Jun Okuda
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Laurent Maron
- LPCNO, UMR 5215, Université de Toulouse-CNRS, INSA, UPS, 31077, Toulouse, France
| | - Ajay Venugopal
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, 695551, India
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Ritter F, Spaniol TP, Douair I, Maron L, Okuda J. Molecular Zinc Hydride Cations [ZnH] + : Synthesis, Structure, and CO 2 Hydrosilylation Catalysis. Angew Chem Int Ed Engl 2020; 59:23335-23342. [PMID: 32931656 PMCID: PMC7756573 DOI: 10.1002/anie.202011480] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Indexed: 01/12/2023]
Abstract
Protonolysis of [ZnH2 ]n with the conjugated Brønsted acid of the bidentate diamine TMEDA (N,N,N',N'-tetramethylethane-1,2-diamine) and TEEDA (N,N,N',N'-tetraethylethane-1,2-diamine) gave the zinc hydride cation [(L2 )ZnH]+ , isolable either as the mononuclear THF adduct [(L2 )ZnH(thf)]+ [BArF 4 ]- (L2 =TMEDA; BArF 4 - =[B(3,5-(CF3 )2 -C6 H3 )4 ]- ) or as the dimer [{(L2 )Zn)}2 (μ-H)2 ]2+ [BArF 4 ]- 2 (L2 =TEEDA). In contrast to [ZnH2 ]n , the cationic zinc hydrides are thermally stable and soluble in THF. [(L2 )ZnH]+ was also shown to form di- and trinuclear adducts of the elusive neutral [(L2 )ZnH2 ]. All hydride-containing cations readily inserted CO2 to give the corresponding formate complexes. [(TMEDA)ZnH]+ [BArF 4 ]- catalyzed the hydrosilylation of CO2 with tertiary hydrosilanes to give stepwise formoxy silane, methyl formate, and methoxy silane. The unexpected formation of methyl formate was shown to result from the zinc-catalyzed transesterification of methoxy silane with formoxy silane, which was eventually converted into methoxy silane as well.
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Affiliation(s)
- Florian Ritter
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 152056AachenGermany
| | - Thomas P. Spaniol
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 152056AachenGermany
| | - Iskander Douair
- CNRSINSAUPSUMR 5215LPCNOUniversité de Toulouse135 avenue de Rangueil31077ToulouseFrance
| | - Laurent Maron
- CNRSINSAUPSUMR 5215LPCNOUniversité de Toulouse135 avenue de Rangueil31077ToulouseFrance
| | - Jun Okuda
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 152056AachenGermany
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Abstract
The first bis(σ-zincane) complexes, heterotri- metallic species [M(CO)4 (η2 -HZnBDI)2 ], have been prepared (BDI=κ2 -{2,6-(iPr)2 C6 H3 NCMe}2 CH). For M=Cr, a single stereoisomer is observed in solution and the solid-state. For M=Mo and W, cis and trans isomers were found to reversibly interconvert at 297 K. Despite the huge steric demands of the ligand on zinc, the cis isomer was found to be the most thermodynamically stable in all cases. The activation parameters for the isomerisation when M=Mo are ΔH≠ =20.8 kcal mol-1 and ΔS≠ =-12.8 cal K-1 mol-1 . In combination with DFT calculations, the negative activation entropy suggests an intramolecular rotation mechanism for isomerisation.
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Affiliation(s)
- Olga Ekkert
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Andrew J P White
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Mark R Crimmin
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
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