Cobalt(II) and cadmium(II) square grids supported with 4,4′-bipyrazole and accommodating 3-carboxyadamantane-1-carboxylate

In poly[[bis(mu-4,40-bi-1H-pyrazole-kappa N-2(2):N-2') bis(3-carboxyadamantane- 1-carboxylato-kappa O-1) cobalt(II)] dihydrate], {[Co(C12H15O4)(2)(C6H6N4)(2)]center dot 2H(2)O}(n), (I), the Co2+ cation lies on an inversion centre and the 4,4'-bipyrazole (4,4'-bpz) ligands are also situated across centres of inversion. In its nonisomorphous cadmium analogue, {[Cd(C12H15O4)(2)(C6H6N4) (2)]center dot 2H(2)O}(n), (II), the Cd2+ cation lies on a twofold axis. In both compounds, the metal cations adopt an octahedral coordination, with four pyrazole N atoms in the equatorial plane [Co-N = 2.156 (2) and 2.162 (2) angstrom; Cd-N = 2.298 (2) and 2.321 (2) angstrom] and two axial carboxylate O atoms [Co-O = 2.1547 (18) angstrom and Cd-O = 2.347 (2) angstrom]. In both structures, interligand hydrogen bonding [N center dot center dot center dot O = 2.682 (3)-2.819 (3) angstrom] is essential for stabilization of the MN4O2 environment with its unusually high (for bulky adamantanecarboxylates) number of coordinated N-donor co-ligands. The compounds adopt two-dimensional coordination connectivities and exist as square-grid [M(4,4'-bpz)(2)] n networks accommodating monodentate carboxylate ligands. The interlayer linkage is provided by hydrogen bonds from the carboxylic acid groups via the solvent water molecules [O center dot center dot center dot O = 2.565 (3) and 2.616 (3) angstrom] to the carboxylate groups in the next layer [O center dot center dot center dot O = 2.717 (3)-2.841 (3) angstrom], thereby extending the structures in the third dimension.