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

摘要

A series of (pseudo)halo(l,3-di-tert-butylimidazol-2-ylidine)gold complexes [(Bu~t_2Im)AuX] (X = Cl,Br,I,CN,N_3,NCO,SCN,SeCN,ONO_2,OCOCH,,CH_3) have been synthesized and characterised spectroscopically and structurally.~(13)C NMR chemical shifts for the carbene carbon vary widely with differing ancillary anion,correlating well with the sigma-donor ability of the latter and with the M-C_((calbene)) bond distance.These results reinforce the notion that N-heterocyclic carbene ligands are primarily a-donor ligands with little pi-acceptor ability.