Reactivity of a Unique Si(I)-Si(I)-Based η2-Bis(silylene) Iron Complex.

In this paper, we report the synthesis of a unique silicon(I)-based metalla-disilirane and report on its reactivity toward TMS-azide and benzophenone. Metal complexes containing disilylenes ((bis)silylenes with a Si-Si bond) are known, but direct ligation of the Si(I) centers to transition metals always generated dinuclear species. To overcome this problem, we targeted the formation of a mononuclear iron(0)-silicon(I)-based disilylene complex via templated synthesis, starting with ligation of two Si(II) centers to iron(II), followed by a two-step reduction. The DFT structure of the resulting η2-disilylene-iron complex reveals metal-to-silicon π-back donation and a delocalized three-center-two-electron (3c-2e) aromatic system. The Si(I)-Si(I) bond displays unusual but well-defined reactivity. With TMS-azide, both the initial azide adduct and the follow-up four-membered nitrene complex could be isolated. Reaction with benzophenone led to selective 1,4-addition into the Si-Si bond. This work reveals that selective reactions of Si(I)-Si(I) bonds are made possible by metal ligation.

Aminolysis of bis[bis(trimethylsilyl)amido]-manganese, -iron, and -cobalt for the synthesis of mono- and bis-silylene complexes.

We report a method for the synthesis of amidinate stabilized silylene (NHSi) metal-halide complexes from M{N(SiMe3)2}2 (M = Mn, Fe, Co). The reported reactions can be used to make mono-silylene or bis-silylene complexes and the resulting products can be easily controlled by the reaction stoichiometry. Additionally, we apply this new synthetic protocol for the synthesis of a bis-iron complex derived from a bis-amidinate ligand having a terphenyl backbone.