Oxidative addition of cyanogen bromide to C,N-chelated and Lappert's stannylenes

Abstract

Stannylenes of L₂Sn type bearing either C,N-chelating (1, L = L^CN = 2-(N,N-dimethylaminomethyl)phenyl) or bulky amido (2, L = L^N = N(SiMe₃)₂) ligands react with cyanogen bromide (Br–CN) via an oxidative-addition reaction to give monomeric six-coordinate (L^CN)₂Sn(Br)CN (1a) and four-coordinate (L^N)₂Sn(Br)CN (2a) stannanes in moderate yields. In solution, both 1a and 2a undergo instantaneous bromido-cyanido ligand redistribution reactions, leading to mixtures containing 1a, (L^CN)₂SnBr₂ (1b) and (L^CN)₂Sn(CN)₂ (1c) or 2a, (L^N)₂SnBr₂ (2b) and (L^N)₂Sn(CN)₂ (2c), respectively. The prepared species were characterised by multinuclear NMR spectroscopy in solution (1a–c and 2a–c) and in the solid state (1a–c). The crystal structures of 1a/b/c, 2a/b/c and sole 2b were determined by XRD analyses. DFT calculations and QTAIM analysis were also carried out to corroborate the experimental results.