Synthetic, structural and spectroscopic studies of (pseudo)halo(1,3-di-tert-butylimidazol-2-ylidine)gold complexes

Abstract

A series of (pseudo)halo(1,3-di-tert-butylimidazol-2-ylidine)gold complexes [(Bu^t₂Im)AuX] (X = Cl, Br, I, CN, N₃, NCO, SCN, SeCN, ONO₂, OCOCH₃, CH₃) have been synthesized and characterised spectroscopically and structurally. ¹³C NMR chemical shifts for the carbene carbon vary widely with differing ancillary anion, correlating well with the σ-donor ability of the latter and with the M–C_(carbene) bond distance. These results reinforce the notion that N-heterocyclic carbene ligands are primarily σ-donor ligands with little π-acceptor ability.