A Zwitterionic Heterobimetallic Gold–Iron Complex Supported by Bis(N‐Heterocyclic Imine)Silyliumylidene

The facile synthesis of the first bis‐N‐heterocyclic imine‐stabilized chlorosilyliumylidene 1 is reported. Remarkably, consecutive reaction of 1 with PPh(3)AuCl and K(2)Fe(CO)(4) gives rise to the unique heterobimetallic complex 1,2‐((Mes)NHI)(2)‐C(2)H(4)‐ClSiAuFe(CO)(4) (4). The overall neutral complex 4 bears an unusual linear Si−Au−Fe structure and a rare anagostic interaction between the d (10)‐configured gold atom and a CH bond of the mesityl ligand. According to the computational analysis and (57)Fe Mössbauer spectroscopy, the formal Fe‐oxidation state remains at −II. Thus, the electronic structure of 4 is best described as an overall neutral—yet zwitterionic—heterobimetallic “Si(II)(+)‐Au(I)(+)‐Fe(‐II)(2−)”‐silyliumylidene complex, derived from double anion exchange. The computational analysis indicates strong hyperconjugative back donation from the gold(I) atom to the silyliumylidene ligand.