The Crystal Structure of [2,6-Bis(1-methyl-4-methylthio-5-thia-2,3-diazahexa-1,3-dienyl)-pyridine]dithiocyanatonickel(II), a Complex of a Potentially Pentadentate N3S2 Ligand, and a Comparison with Complexes of an N3O2 Ligand

Abstract

The crystal structure of Ni(dapsm)(NCS)2 [dapsm is 2,6-bis(1-methyl-4-methylthio-5-thia-2,3-diazahexa-1,3-dienyl)pyridinel has been determined from three-dimensional single-crystal diffractometer X-ray data. Structure refinement was carried out by least-squares methods to a final R value of 0.059. The ligand dapsm is a potential N3S2 pentadentate, but it coordinates as a tetradentate, giving a planar N3S donor grouping. Rotation occurs about an N-N bond in dapsm, moving a potential donor sulfur atom away from the nickel(II) ion. The pyridine ring of the ligand, and the N3S donor grouping, are approximately coplanar. Two thiocyanate groups are coordinated to the nickel, giving a distorted octahedral structure. The structure and electronic spectrum of Ni(dapsm)- (NCS)2 are compared with those for seven-coordinate complexes with the related N3O2 ligand, 2,6-diacetylpyridine bissemicarbazone.