Zinc Catalysts for On-Demand Hydrogen Generation and Carbon Dioxide Functionalization

Abstract

[Tris(2-pyridylthio)methyl]zinc hydride, [κ(3)-Tptm]ZnH, is a multifunctional catalyst that is capable of achieving (i) rapid release of hydrogen by protolytic cleavage of silanes with either water or methanol and (ii) hydrosilylation of aldehydes, ketones, and carbon dioxide. For example, [κ(3)-Tptm]ZnH catalyzes the release of 3 equivalents of H(2) by methanolysis of phenylsilane, with a turnover number of 10(5) and a turnover frequency surpassing 10(6) h(-1) for the first 2 equivalents. Furthermore, [κ(3)-Tptm]ZnH also catalyzes the formation of triethoxysilyl formate by hydrosilylation of carbon dioxide with triethoxysilane. Triethoxysilyl formate may be converted into ethyl formate and N,N-dimethylformamide, thereby providing a means for utilizing carbon dioxide as a C(1) feedstock for the synthesis of useful chemicals.

Mechanistic studies on the N-formylation of amines with CO2 and hydrosilane catalyzed by a Cu–diphosphine complex

“…2 Additionally, silyl formate was reported to react with various amines, affording the corresponding formamides. 4,8 This encouraged us to clarify the formation of silyl formate as the reaction intermediate for the N-formylation of amines catalyzed by our Cu salt/diphosphine ligand catalyst system. To elucidate the reaction pathway for the N-formylation reaction, the time course of the initial period of the N-formylation of piperidine with triethylsilane (Et 3 SiH) using Cu(OAc) 2 $H 2 O and a diphosphine ligand, 1,2-bis(diisopropylphosphino)benzene (Chart 1, 1), was investigated.…”

Tuning of photocatalytic activity by creating a tridentate coordination sphere for palladium

“…34,49 As the 2,9-arylated-phen sphere of Ru(bmptpphz) should be capable of stabilizing a large variety of metal cations like Ni 2+ , Co 2+ , Cu + and Zn 2+ , 54 which are known to be active centres for catalytic hydrogen formation, a quite large number of potentially stable heterodinuclear photocatalysts is accessible. [55][56][57] Moreover, as the p-anisyl-substituents can easily be converted to hydroxyphenyl substituents, they provide the opportunity for further synthetic coupling, which makes Ru-(bmptpphz) an interesting candidate concerning its application as building block for artificial molecular machines. 58 For instance, an interlock of Ru(bmptpphz) with catenane or rotaxane like architectures, which are used for the construction of molecular machines and motors, seems to be feasible.…”

Reduction of carbon dioxide and organic carbonyls by hydrosilanes catalysed by the perrhenate anion

“…[1][2][3] A variety of catalysts have been discovered and developed for this reaction, including complexes of Co, 4 Cu, [5][6][7][8] Ir, [9][10][11][12][13][14] Ni, [15][16][17] Pd/Pt, 18 Rh, 19 Ru, [20][21][22][23][24][25] Sc, 26 Zn, [27][28][29] and Zr, 30 frustrated Lewis pairs, [31][32][33][34][35][36] organocatalysts, [37][38][39][40][41][42] alkali metal carbonates, 43 and even polar solvents such as DMF. 38 These reactions result in various reduction products including silyl-formates, -acetals, andethers, CO, and methane.…”