Diorgano-gallium and -indium complexes with N-heterocyclic carboxylic acids: Synthesis, characterization and structures of [Me2M(O2C–C5H4N)]2, M = Ga or In

The reaction of triorgano-gallium and -indium etherate with heterocyclic carboxylic acids in benzene at room temperature yields complexes of the type [R2M(L)]n(M = Ga or In; R = Me or Et; L = 2-(C5H4N)CO2, 2-(C4H3N2)CO2 or 2-(C9H6N)CO2). These complexes have been characterized by elemental analysis, IR, UV–vis, NMR (1H and 13C{1H}) and mass spectral data. Complexes with L = (C5H4N)CO2- and (C9H6N)CO2- showed photoluminescence on excitation with ∼250 or ∼310 nm radiation, respectively. Single crystal X-ray structural analysis of [Me2M(O2C–C5H4N-2)]2 (M = Ga or In), revealed a dimeric structure with five-coordinate metal atoms arising from the presence of two tridentate bridging picolinate ligands.