Solid state coordination chemistry of copper(II)/α-hydroxycarboxylato/2,2′-bipyridine systems |
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Authors: | Rosa Carballo, Alfonso Casti eiras, Susana Balboa, Berta Covelo,Juan Nicl s |
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Affiliation: | Rosa Carballo, Alfonso Castiñeiras, Susana Balboa, Berta Covelo,Juan Niclós |
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Abstract: | Four new two-ligand complexes of copper(II) with 2,2′-bipyridine and one of three different α-hydroxycarboxylic acids (lactic, H2LACO; 2-methyllactic, H2MLACO; and mandelic, H2MANO) were prepared. Complexes 1–3 of general formula [Cu(HL)2(bipy)]·nH2O (HL=monodeprotonated acid), were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermogravimetric analysis. Complexes 1 (HL=HLACO, n=2), 2 (HL=HMLACO, n=1) and 3a (the result of attempted recrystallization of 3, of formula [Cu(HMANO)(bipy)2](HMANO)·H2MANO·CH3CN were studied by X-ray diffractometry. The copper atom is in an elongated, tetragonally distorted octahedral environment in 1 and 2 and in 3a has a coordination polyhedron intermediate between a square pyramid and a trigonal bipyramid, as evaluated in terms of the parameter τ. In 1 and 2 the α-hydroxycarboxylato ligand is bidentate and monoanionic but in 3a there are three forms: a monodentate monoanion, a monoanionic counterion, and a neutral molecule. |
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Keywords: | Mixed-ligand complexes Copper(II) complexes 2,2′ -Bipyridine complexes Lactic acid 2-Methyllactic acid Mandelic acid Crystal structures |
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