Mixed-ligand complexes of copper(II) and alpha-hydroxycarboxylic acids and1,10-phenanthroline

Eight new two-ligand complexes of copper(II) with 1,10-phenanthroline and o ne of four different a-hydroxycarboxylic acids (glycolic, lactic, mandelic and benzylic) were prepared. The complexes of general formula [Cu(HL)2(phen )l (.) nH(2)O (HL = monodeprotonated acid) (1-4) were characterized by elem ental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermo-gravimetric analysis. The complexes of general formulae [Cu(HL)( phen)(2)](HL) (.) H2L (.) nSolv [1a (HL = HGLYO(-), n = 1, Solv = MeCN) and 3a (HL = HMANO(-), n = 0)] and [Cu(L)(phen)(OH2)] (.) nH(2)O [2a (L = LACO (2-), n = 4) and 4a (L = BENO2-. n = 2)1 were characterized by X-ray diffra ctometry. In all these latter a pentacoordinated copper atom has a basicall y square pyramidal coordination polyhedron, the distortion of which towards a trigonal bipyramidal configuration has been evaluated in terms of the pa rameter tau. In la and 3a there are three forms of alpha -hydroxycarboxylic acid: a monodentate monoanion, a monoanionic counterion, and a neutral mol ecule lying in the outer coordination sphere; in 2a and 4a the cx-hydroxyca rboxylic acid is a bidentate dianion coordinating through carboxyl and hydr oxyl oxygens.