A Molecular Complex with a Formally Neutral Iron Germanide Motif (Fe₂Ge₂)

Abstract

We report the synthesis and isolation of a stable complex containing the formally neutral Fe₂Ge₂ motif, which is stabilized by the coordination of an N-heterocyclic carbene to the germanium and of carbon monoxide to the iron center. [(NHC^{<i>i</i>Pr₂Me₂})­GeFe­(CO)₄]₂ is obtained by reduction of the NHC^{<i>i</i>Pr₂Me₂}-coordinated dichlorogermylene adduct of Fe­(CO)₄, which in turn is obtained from the reaction of Fe₂(CO)₉ with GeCl₂·NHC^{<i>i</i>Pr₂Me₂} (NHC^{<i>i</i>Pr₂Me₂} = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene). The solid-state structure of the title compound reveals two distinct coordination modes for the Fe­(CO)₄ fragments: bridging (π-type) and terminal (σ-type). In solution, the rapid equilibrium between the two modes was resolved by NMR at −35 °C. Reaction with propylene sulfide at room temperature affords the sulfide-bridged digermanium complex with two terminal Fe­(CO)₄ moieties