Synthesis and ligand properties towards gold and silver of the ferrocenylamidobenzimidazole ligand

Abstract

The treatment of FcCOCl (Fc = (C 5H 5)Fe(C 5H 4)) with aminobenzimidazole in 1:1 or 2:1 ratio gives the ferrocenyl-amido derivatives FcCO(benzimNH 2) or (FcCO) 2(NHbenzim), respectively. The reactivity of FcCO(benzimNH 2) with silver or gold complexes has been studied. The reaction with the basic gold compounds [Au(acac)(PPh 3)] or [O(AuPPh 3) 3]ClO 4 occurs with deprotonation of the NH 2 group and coordination of one or three gold(phosphine) fragments. The treatment of this ligand with silver compounds, such as Ag(OTf) or [Ag(OTf)(PPh 3)], gives the complexes of stoichiometry [Ag(OTf)L] or [Ag(OTf)(PPh 3)L]. The ligand FcCO(benzimNH 2) and the complex [Ag(OTf){FcCO(benzimNH 2)}(PPh 3)] have been characterized by X-ray diffraction studies. DFT calculations were performed on models of this dimeric silver complex and showed that dimerization is energetically favourable, because Ag(I) achieves a four coordination environment, despite some bonds being relatively weak.