Bond angle of isothiocyanate. Molecular network of cobalt(II) isothiocyanate with bis(3-pyridyl)dialkylsilanes

The reaction of Co(NCS)(2) with L produces the coordination polymers of [Co(NCS)(2)L-2] unit (L = bis(3-pyridyl)cyclotetramethylenesilane (bpcms) and bis(3-pyridyl)dimethylsilane (bpdms)). Each L linker connects two cobalt(II) ions defining the edges of a 32-membered [Co-11](4), thus forming a 2D grid sheet structure. The local geometry of the cobalt(II) ion is an octahedral arrangement with two NCS groups in trans position and four pyridine units in a propeller fashion building the basal plane. Difference between dimethyl and cyclotetramethylene moieties of two spacer ligands induces delicate structural difference. The Co-N-CS angle of [Co(NCS)(2)(bpdMS)(2)] is severely bent (Co-N-C = 153.9(2)degrees) in contrast to the corresponding angle (Co-N-C = 180.0degrees) of [Co(NCS)(2)(bpdms)(2)]. The degree of the Co-N-CS angle seems to be determined by steric or packing effects rather than electronic effects. (C) 2003 Elsevier B.V. All rights reserved.