Diorgano-gallium and -indium complexes with salen ligands: Synthesis, characterization, crystal structure and C–C coupling reactions

The reactions of triorgano-gallium and -indium etherate with salen ligands in benzene afforded complexes of the type [R2MOC6H4CR′double bond; length as m-dashNCH2–]2, (R/M/R′ = Me/Ga/H (1), Et/Ga/H (2), Me/In/H (3), Et/Ga/Me (4)) in nearly quantitative yields. These complexes have been characterized by elemental analysis, IR, UV–Vis, NMR (1H and 13C{1H}) and mass spectral data. The organogallium complexes showed photoluminescence in blue-green region. The complex, [(Me2Ga)2(O–(C6H4)CHdouble bond; length as m-dashN–CH2–)2] on recrystallization from benzene–hexane and dichloromethane gave orthorhombic and monoclinic forms, respectively. Both the forms are dimeric with gallium atoms acquiring a distorted tetrahedral configuration defined by two methyl groups, phenolate oxygen and azomethene nitrogen. The complexes [(Me2Ga)2(O–(C6H4)CHdouble bond; length as m-dashN–CH2–)2] and [(Me2In)2(O–(C6H4)CHdouble bond; length as m-dashN–CH2–)2] have been employed as alkylating agent for C–C coupling reaction of 1-bromonaphthalene in presence of PdCl2(PPh3)2.