Crystal structures of two Co(NCS)2 urotropine coordination compounds with different Co coordinations

Abstract

The reaction of Co(NCS)2 with urotropine in ethanol leads to the formation of two different compounds, namely, bis(ethanol-κO)bis(hexamethylenetetramine-κN)bis(thiocyanato-κN)cobalt(II)–diaqua-κ 2O-bis(hexamethylenetetramine-κN)bis(thiocyanato-κN)cobalt(II)–ethanol–hexamethylenetetramine (1.2/0.8/1.6/4), [Co(NCS)2(C6H12N4)2(C2H6O)2]1.2·[Co(NCS)2(C6H12N4)2(H2O)2]0.8·1.6C2H6O·4C6H12N4, 1, and tris(ethanol-κO)(hexamethylenetetramine-κN)bis(thiocyanato-κN)cobalt(II), [Co(NCS)2(C6H12N4)(C2H6O)3], 2. In the crystal structure of compound 1, two crystallographically independent discrete complexes are observed that are located on centres of inversion. In one of them, the Co cation is octahedrally coordinated to two terminal N-bonded thiocyanate anions, two urotropine ligands and two ethanol molecules, whereas in the second complex 80% of the coordinating ethanol is exchanged by water. Formally, compound 1 is a mixture of two different complexes, i.e. diaquadithiocyanatobis(urotropine)cobalt(II) and diethanoldithiocyanatobis(urotropine)cobalt(II), that contain additional ethanol and urotropine solvate molecules leading to an overall composition of [Co(NCS)2(urotropine)2(ethanol)1.2(H2O)0.8·0.8ethanol·4urotropine. Both discrete complexes are linked by intermolecular O—H...O and O—H...N hydrogen bonding and additional urotropine solvate molecules into chains, which are further connected into layers. These layers combine into a three-dimensional network by pairs of centrosymmetric intermolecular C—H...S hydrogen bonds. In the crystal structure of compound 2, dithiocyanato(urotropine)triethanolcobalt(II), the cobalt cation is octahedrally coordinated to two terminal N-bonded thiocyanate anions, one urotropine ligand and three ethanol molecules into discrete complexes, which are located in general positions. These complexes are linked by intermolecular O—H...N hydrogen bonding into layers, which are further connected into a three-dimensional network by intermolecular C—H...S hydrogen bonding.