Abstract

The two isomorphous title structures, formulated as {[Co(C10H4O8)(C12H10N2) (H2O)2]·C12H10N2} n , (I), and {[Co(C10H4O8)(C12H12N2)(H2O)2] ·C12H12N2} n , (II), respectively, are reported. They crystallize in the space group P with only one formula unit in the asymmetric unit, so that the organic ligands lie about inversion centres and the Co atom lies on an inversion centre. The Co atoms are octa-hedrally coordinated by a carboxyl-ate O atom from 2,5-dicarboxy-benzene-1,4-dicarboxyl-ate (H2btc), one N atom from 1,2-di-4-pyridyl-ethene (L) in (I) or from 1,2-di-4-pyridylethane (L) in (II), and one coordinated water mol-ecule, plus their inversion-related species. This particular coordination results in a two-dimensional array, with an elemental unit in the shape of a parallelogram having the Co II cations at the corners, linked in one direction by L bridges and in the opposite direction by H2btc groups. The L solvent mol-ecules act as pillars between parallel planes, linking them by strong hydrogen bonds where the H atoms lie midway between the formal donor/acceptor atoms in a shared mode. Comparison is made with structures presenting the same structural motif, strongly suggesting that the two-dimensional arrangement reported here might be a very stable robust building block for mol-ecular engineering purposes. © 2009 International Union of Crystallography.