S. Massoud, L. Quan, K. Gatterer
Jan 4, 2012
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Polyhedron
Abstract
The reaction of M(ClO 4 ) 2 ·6H 2 O with NH 4 NCS in presence of the organic sterically hindered bis(2-(di-3,5-dimethyl-1-pyrazolyl)ethyl)amine (bedmpza) afforded the five-coordinate mononuclear dithiocyanato–M(II) complexes [M(bedmpza)(NCS) 2 ]· x MeOH ( 1 : M = Cu 2+ , x = 0; 2 : M = Ni 2+ , x = 0; 3 : M = Co 2+ , x = 0.84). The compounds which proved to be non-electrolytes were characterized by IR and UV–Vis spectroscopy and their molecular structures were determined by single-crystal X-ray crystallography. In these complexes, the five-coordinate geometry was achieved by the three N-donors of the ligand bedmpza and two N atoms of the terminal thiocyanato ligands. The Cu(II) complex exists in two polymorphs 1-I and 1-II : an intermediate five-coordinate geometry with the two thiocyanato ligands are arranged as cisoid in 1-I and distorted square pyramidal geometry with the thiocyanato ligands are in transoid orientation in 1-II . Although the later geometry was also observed in the nickel complex 2 , distorted trigonal bipyramidal geometry was found in 3 . Each complex forms hydrogen bonds of type N–H⋯S from the secondary amine N(3) donor atoms to the adjacent terminal S(1) acceptor atoms of the thiocyanate group. The thermal behavior of the two polymorphs 1-I and 1-II were similar and no significant differences were observed between the two complexes.