Different Reactivity Patterns in the Reactions of the Homologous Trimethylelement Compounds EMe3 (E = Al, Ga, In) with Methylhydrazine

The trimethylelement compounds EMe3 (E = Al, Ga, In) followed three different reaction courses upon treatment with methylhydrazine, H2N–N(H)Me. AlMe3 reacted at room temperature by releasing 1.5 equiv. methane to yield the sesquihydrazide (Me2Al)3[μ‐NH–N(H)Me]6Al (1), which in the solid state has a hexacoordinate central aluminum atom and six hydrazido groups in the bridging positions to the three terminally arranged AlMe2 groups. Dissociation occurred upon dissolution, and the dialuminum compound Me2Al[μ‐NH–N(H)Me]2Al(Me)[NH–N(H)Me] (2), containing one terminal hydrazido group, was identified unambiguously by NMR spectroscopy. GaMe3 gave a simple adduct, Me3Ga←N(H)Me–NH2 (3), under the same reaction conditions. Boiling toluene was required to initiate a secondary reaction with the release of methane. A bicyclic tetragallium compound, 4, in which a twofold deprotonated hydrazide, [HN–NMe]2–, bridges four gallium atoms, was the result. Each pair of gallium atoms on both sides of the central hydrazinediide ligand is further bridged by the monoanionic hydrazide [HN–N(H)Me]– to yield two annelated, five‐membered Ga2N3 heterocycles. A similar compound, 5, was directly obtained from the reaction of InMe3 with methylhydrazine at room temperature.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)