Structural and magnetic properties of three copper(II) pyridine-2,3-dicarboxylate coordination polymers incorporating the same chain motif

The complex [Cu(2,3-pydcH)(2)], (1), (2,3-pydcH(2) = 2,3-pyridinedicarboxylic acid) is a chain polymer. Two ligands occupy the equatorial plane of each tetragonally elongated octahedral Cu2+ coordination sphere, chelating through the pyridine nitrogen and one oxygen of the deprotonated 2-carboxylic acid group; the axial positions are occupied by long bonds to a 3-carboxylic acid oxygen of adjacent Cu(2,3-pydcH)(2) repeat units. This polymeric chain motif also appears in two heterometallic complexes incorporating the doubly deprotonated dicarboxylate ligand species 2,3-pydc; namely [Cu(2,3-pydc)(2)][Na-2(H2O)(6)(mu-H2O)(2)], (2), and [Cu(2,3-pydc(2)][Mn(H2O)(6)]center-dot2H(2)O, (3). In 2, the chains are cross-linked via a novel disodium cation [Na-2(H2O)(6)(mu-H2O)(2)](2+) to form a 2D sheet structure. In 3, the chains carry a formal 2- charge per copper centre, with charge neutrality achieved by the presence of isolated [Mn(H2O)(6)](2+) complex cations in the lattice. The structural and magnetic properties of these three species are compared. (C) 2003 Elsevier Ltd. All rights reserved.