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 PPh3AuCl and K2Fe(CO)(4) gives rise to the unique heterobimetallic complex 1,2-((NHI)-N-Mes)(2)-C2H4-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 Fe-57 Mossbauer 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.

Automated summary

The facile synthesis of the first bis-N-heterocyclic imine-stabilized chlorosilyliumylidene and its consecutive reaction with PPh3AuCl and K2Fe(CO)(4) resulted in the formation of a unique heterobimetallic complex. The complex bears an unusual linear Si-Au-Fe structure with a rare anagostic interaction between the gold atom and a CH bond. Computational analysis shows strong hyperconjugative back donation from the gold(I) atom to the silyliumylidene ligand.