Crystal structure of bis(biimidazole-k2N,N')- bis(isothiocyanato-kN)cobalt(II)-dimethylsulfoxide (1:2), Co(C6H6N4)2(NCS)2 · 2C2H6SO

Abstract

Source of materialAn aqueoussolution(5mL) of cobalt sulphate (1 mmol, 0.250 g) was slowly poured dropwise into ahot aqueous solution (3 ml) of ammonium thiocyanate (1 mmol, 0.0761 g). The mixture was stirred for 10 mins. 2,2'-Biimidazole (H 2 biim,1mmol, 0.134 g) and DMSO (4 ml)were added to this mixture. The resultant mixture was refluxed for 30 min and then allowed to cool to ambient temperature. The insoluble residues were removed by filtration, andt he filtrate wase vaporateds lowlya tr oomt emperature for aboutone week to yieldpinkcrystalline product. Block-shaped crystals suitable for single crystal X-ray diffraction were selected directly from theproduct. Experimental detailsThedisorder of DMSO andisothiocyanategroupsisthe resultof intensethermal vibration of the terminal group, which is also responsible for the huge R values.The occupation parameters were obtained by normalization refinement. There is no relationship betweenthe parameters.S1and C9 were refinedwithc ommon ADPs, because areasonable occupation could be obtained. DiscussionMetal-organic supramolecular compounds have received much attention due to their structural diversities and potential applications as new materials [1][2][3][4][5]. The consideration and utilization of the coordination bonds, intermolecular hydrogen bonds and p-p packing interactions helps to control the molecular arrangement. H 2 biim is an excellent candidate for building as upramolecular structure involving directed hydrogen bonding interactions. The uncoordinated N-H groups in H 2 biim participate in various hydrogen bonds with counter anions or other acceptors [6][7][8]. We focus on the synthesis of metal-biimidazole supramolecular compounds [9][10][11]. The asymmetric unit of the title crystal structure consists of the neutral moiety [Co(C 6 H 6 N 4 ) 2 (NCS) 2 ]and two free DMSO molecules. The coordination environment around the Co(II) atom can be described as ad istorted octahedron. Four nitrogen atomso f twoc helate H 2 biim ligands form the equatorial plane of the octahedron, whereas the apical positions are occupied by nitrogen atomsf rom two isothiocyanate anions. The difference of .M olecular packing is controlled to ag reat extent by the ability of coordinatedH 2 biim to form hydrogen bonds with solvent molecules.