M. Hvastijova et al., DICYANAMIDE COMPLEXES OF COPPER(II), NICKEL(II) AND COBALT(II) WITH BENZIMIDAZOLE AND ITS 2-ALKYL-DERIVATIVES, Transition metal chemistry, 18(6), 1993, pp. 579-582
Dicyanamide complexes of Cu-II, Ni-II and Co-II of the type M[N(CN)(2)
](2)L(2), where L=benzimidazole, 2-methyl- or 2-ethylbenzimidazole, ha
ve been prepared and studied by spectroscopy and magnetochemistry. The
complexes, except for Co[N(CN)(2)](2) (benzimidazole)(2), are six-coo
rdinate, involving bidentate bridging dicyanamide groups. While the Ni
-II complexes have practically octahedral structures, the Cu-II comple
xes are pseudooctahedral with similar tetragonal distortion. The ligan
d held strength in these complexes depends mainly on the steric effect
of the benzimidazole ligands. The Co-II complex of benzimidazole is m
onomeric tetrahedral, but that of 2-ethylbenzimidazole is tetragonal o
ctahedral. The oridging function of dicyanamide in the six-coordinate
complexes is realized either through both cyanide or through amide and
cyanide nitrogens. The complex Cu[N(CN)(2)](2) (2-methylbenzimidazole
)(2) is a weak antiferromagnet (J=-O.1cm(-1)), exhibiting under ca. 15
K a long-range antiferromagnetic ordering.