Catalytic cyanosilylation of ketones utilizing air-stable zinc complexes supported by amidophosphine chalcogenide ligands

Abstract

We report the synthesis and structural characterization of a series of novel zinc (II) and cadmium (II) complexes with the chemical composition, [κ2-N,E-{C5H4NCH2N(H)PPh2(E)}MX2] (M = Zn; E = Se, X = Cl (1a), Br (1b), I (1c); E = S, X = Cl (2a), Br (2b), I (2c) and M = Cd; E = Se, X = Cl (3a), I (3b); E = S, X = Cl (4a), I (4b)). These complexes are easy to prepare and air-stable. The single-crystal X-ray diffraction analysis of the complexes 1a-1c, 2a-2c, 3b, and 4b reveals that these complexes are isostructural and involve a seven-membered ring formed by the coordination of soft donor atoms (S/Se), pyridine nitrogen atom, and zinc/cadmium metal. The zinc metal complexes 1a-1c and 2a-2c were explored as pre-catalysts for the cyanosilylation of ketones with trimethylsilyl cyanide. The catalyst 1c showed excellent activity at room temperature under solvent-free conditions and demonstrated high tolerance toward a number of functional groups.