Tetrahedral complexes of nickel(II) with benzimidazole

Abstract

The preparations are described of the benzimidazole (=L) complexes, NiL₂X₂(X = Br or I) and (Et₄N)(NiLBr₃). From their electronic spectra and magnetic properties these compounds are assigned pseudo-tetrahedral configurations, but with pronounced departures from T_d symmetry. The magnetic moments of NiL₂Br₂ and (Et₄N)(NiLBr₃) decrease from 3·46 and 3·57 B.M., respectively, at room temperature to about the spin-only value at ca. 4·2°K. The moments of (MePh₃As)₂NiCl₄ and Ni(Ph₃P)₂Cl₂, at ca. 4·2°K are 0·70 and 2·20 B.M., respectively. Solution equilibria between 2 : 1 and 4 : 1 complexes of L with the nickel halides are also reported.