Reaction of a Germylene, Stannylene, or Plumbylene with Trimethylaluminum and Trimethylgallium: Insertion into Al–C or Ga–C Bonds, a Reversible Metal–Carbon Insertion Equilibrium, and a New Route to Diplumbenes

The reaction of the tetrylenes Ge(Ar Me 6 )2, Sn(Ar Me 6 )2, and Pb(Ar Me 6 )2 [Ar Me 6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with the group 13 metal alkyls trimethylaluminum and trimethylgallium afforded (Ar Me 6 )2Ge(Me)AlMe2 (1), (Ar Me 6 )2Ge(Me)GaMe2 (2), and (ArMe6 )2Sn(Me)GaMe2 (3) in good yields via insertion reaction routes. In contrast, the reaction of AlMe3 with Sn(Ar Me 6 )2 afforded the [1.1.1]propellane analogue Sn2{Sn(Me)Ar Me 6 }3 (5) in low yield, and the reaction of AlMe3 or GaMe3 with Pb(Ar Me 6 )2 resulted in the formation of the diplumbene {Pb(Me)Ar Me 6 }2 (6) and AlAr Me 6 Me2 (7) or GaAr Me 6 Me2 (8) via metathesis. The reaction of Sn(Ar Me 6 )2 with gallium trialkyls was found to be reversible under ambient conditions and analyzed through the reaction of Sn(Ar Me 6 )2 with GaEt3 to form (Ar Me 6 )2Sn(Et)GaEt2 (4), which displayed a dissociation constant K diss and ΔG diss of 8.09(6) × 10–3 and 11.8(9) kJ mol–1 at 296 °C. The new compounds were characterized by X-ray crystallography, NMR (1H, 13C, 119Sn, and 207Pb), IR, and UV–vis spectroscopies.