Dimetalloylene (M‐E‐M) Complexes of Heavier Main Group Elements Ge, Sn, Pb, Bi via Cleavage of E‐X Bonds (X=N(SiMe3)2, OtBu) with an Iridium Hydride

Abstract

AbstractReactions of the IrV hydride [MeBDIDipp]IrH4 {BDI=(Dipp)NC(Me)CH(Me)CN(Dipp); Dipp=2,6‐iPr2C6H3} with E[N(SiMe3)2]2 (E=Sn, Pb) afforded the unusual dimeric dimetallotetrylenes ([MeBDIDipp]IrH)2(μ2‐E)2 in good yields. Moreover, ([MeBDIDipp]IrH)2(μ2‐Ge)2 was formed in situ from thermal decomposition of [MeBDIDipp]Ir(H)2Ge[N(SiMe3)2]2. These reactions are accompanied by liberation of HN(SiMe3)2 and H2 through the apparent cleavage of an E−N(SiMe3)2 bond by Ir−H. In a reversal of this process, ([MeBDIDipp]IrH)2(μ2‐E)2 reacted with excess H2 to regenerate [MeBDIDipp]IrH4. Varying the concentrations of reactants led to formation of the trimeric ([MeBDIDipp]IrH2)3(μ2‐E)3. The further scope of this synthetic route was investigated with group 15 amides, and ([MeBDIDipp]IrH)2(μ2‐Bi)2 was prepared by the reaction of [MeBDIDipp]IrH4 with Bi(NMe2)3 or Bi(OtBu)3 to afford the first example of a “naked” two‐coordinate Bi atom bound exclusively to transition metals. A viable mechanism that accounts for the formation of these products is proposed. Computational investigations of the Ir2E2 (E=Sn, Pb) compounds characterized them as open‐shell singlets with confined nonbonding lone pairs at the E centers. In contrast, Ir2Bi2 is characterized as having a closed‐shell singlet ground state.