Layered crystal structure of the trans(O5O6) isomer of potassium (1,3-propanediamine-N,N '-diacetato-N,N '-di-3-propionato) cobaltate(III) trihydrate, trans(O5O6)-K[Co(1,3-pddadp)] center dot 3H(2)O, stabilized by ionic, hydrogen bond and C=O dipolar inte

The hexadentate trans(O5O6)-K[Co(1,3-pddadp)] (.) 3H(2)O complex (where 1,3-pddadp represents the 1,3-propanediamine-N,N'-diacetate-N,N'-di-3-propionate ion) has been characterized by single-crystal X-ray crystallography. The complex crystallizes in the P2/c space group of the monoclinic crystal system. In the crystal structure of trans(O5O6)-K[Co(1,3-pddadp)] (.) 3H(2)O the potassium ions and two solvent water molecules (O1W and O3W) are settled on a twofold axis of symmetry. The octahedral complex units trans(O5O6)-[Co(1,3-pddadp)](-) are bridged by carboxylate oxygen atoms with the potassium ions to build a two-dimensional polymer structure, separated by layers formed by hydrogen bonded water molecules and carboxylate oxygens. The coordination polyhedra around K1 and K2 are found to be distorted square antiprism and twisted bi-capped trigonal prism, respectively. Conformational analysis of the three possible geometrical isomers (trans(O-5), trans(O5O6) and trans(O-6)) of the [Co(1,3-pddadp)]- complex, was performed using the Consistent Force Field (CFF) program, with the parameters developed previously for edta-type complexes and new parameters for Co(III). Molecular mechanics (MM) calculations reproduced very well the crystallographically characterized structures (trans(O5O6)-[Co(1,3-pddadp)](-) and trans(O-6)-[Co(1,3-pddadp)](-))