The hydrogallation of CN double bonds — reactions of GaH3·NMe2Et with tetramethyl-2,3-diazabutadiene

The reaction of 1,1,4,4-tetramethyl-2,3-diazabutadiene with GaH3·NMe2Et yielded two different products depending on the reaction conditions. The hydrogallation of only one CN double bond was observed at low temperature and for a 1:1 molar ratio of the starting compounds. The resulting dimeric gallium hydrazonide [H2GaN(iPr)NCMe2]2 (4) has a six-membered Ga2N4 heterocycle in its molecular centre. In contrast, NN bonds were partially cleaved when the same reaction was carried out at room temperature with an excess of the gallane–amine adduct. The structure of the tricyclic tetragallium compound {(GaH)(GaH2)(NiPr)[N(iPr)NCMe2]}2 (5) isolated in low yield consists of two five-membered Ga2N3 heterocycles anellated to a central four-membered Ga2N2 ring.