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

Reactions of the Ir hydride [ BDI ]IrH {BDI=(Dipp)NC(Me)CH(Me)CN(Dipp); Dipp=2,6-iPr C H } with E[N(SiMe ) ] (E=Sn, Pb) afforded the unusual dimeric dimetallotetrylenes ([ BDI ]IrH) (μ -E) in good yields. Moreover, ([ BDI ]IrH) (μ -Ge) was formed in situ from thermal decomposition of [ BDI ]Ir(H) Ge[N(SiMe ) ] . These reactions are accompanied by liberation of HN(SiMe ) and H through the apparent cleavage of an E-N(SiMe ) bond by Ir-H. In a reversal of this process, ([ BDI ]IrH) (μ -E) reacted with excess H to regenerate [ BDI ]IrH . Varying the concentrations of reactants led to formation of the trimeric ([ BDI ]IrH ) (μ -E) . The further scope of this synthetic route was investigated with group 15 amides, and ([ BDI ]IrH) (μ -Bi) was prepared by the reaction of [ BDI ]IrH with Bi(NMe ) or Bi(OtBu) 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 Ir E (E=Sn, Pb) compounds characterized them as open-shell singlets with confined nonbonding lone pairs at the E centers. In contrast, Ir Bi is characterized as having a closed-shell singlet ground state.