Coordination polymers of copper(II) based on mixed N- and O-donor ligands:: the crystal structures of [CuL2(4,4′-bipy)]n (L = lactate or 2-methyllactate)

The neutral polymeric complexes of copper(II) [CuL2(4,4'-bipy)](n), where L is an alpha -hydroxycarboxylato ligand, lactate in 1, 2-methyllactate in 2, were prepared and characterised structurally. The copper atom is in an elongated tetragonally distorted octahedral environment in both compounds. Both alpha -hydroxycarboxylato ligands are O,O'-bidentate chelating monoanions and 4,4'-bipyridine acts as an N,N'-bis(monodentate) bridging ligand creating a linear polymeric arrangement. The polymeric chains are interconnected by O-hydroxyl-H . . .O-carboxy hydrogen bonds in a way that creates cavities that differ in size between 1 and 2. Spectroscopic data are presented and discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.