Efficient CO₂ Insertion and Reduction Catalyzed by a Terminal Zinc Hydride Complex

Abstract

The terminal zinc hydride complex [Tntm]ZnH (2; Tntm=tris(6-tert-butyl-3-thiopyridazinyl)methanide) is an efficient hydrosilylation catalyst of CO₂ at room temperature without the need of Lewis acidic additives. The inherent electrophilicity of the system leads to selective formation of the monosilylated product (MeO)₃ SiO₂ CH (at room temperature with a TOF of 22.2 h^-1 and at 45 °C with a TOF of 66.7 h^-1 ). In absence of silanes, the intermediate formate complex [Tntm]Zn(O₂ CH) (3) is quantitatively formed within 5 min. All complexes were fully characterized by ¹ H and ¹³ C NMR spectroscopy and single-crystal X-ray diffraction analyses. Density functional theory (DFT) calculations reveal a high positive charge on zinc and the increased preference of the ligand to adopt a κ³ -coordination mode.