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

The reaction of Co(NCS)2 with L produces the coordination polymers of [Co(NCS)2L2] unit (L ¼ 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 [CoII]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 ¼ 153.9(2)8) in contrast to the corresponding angle (Co–N–C ¼ 180.08) 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. q 2003 Elsevier B.V. All rights reserved.