Cobalt(II), nickel(II), and copper(II) complexes of 4(5)-bromoimidazole

Abstract

The preparation and spectral and magnetic properties are reported for complexes of cobalt(II), nickel(II) and copper(II) with 4(5)-bromoimidazole (Blz). The compounds (Blz)₆CoCl₂, (Blz)₄NiX₂(X = Cl, Br, or I), and (Blz)₂NiX₂(X = Cl or Br) possess essentially octahedral structures, whilst (Blz)₂CoX₂(X = Cl, Br, or I) and (Blz)₂Nil₂ are pseudotetrahedral. The compounds (Blz)₂CuX₂(X = Cl or Br) and (Blz)₄CuBr₂ have tetragonally distorted pseudo-octahedral structures. The structures of the ‘inner’ complexes (Blz′)₂M (Blz′= C₃H₂BrN₂, M = Co, Ni, or Cu) are described. The compounds (Blz)₆NiCl₂, (Blz)₄CuCl₂, and (Blz)₆CuCl₂ are shown to contain clathrated 4(5)-bromoimidazole. In the octahedral complexes the organic ligand is considered to be 5-bromoimidazole. The stoicheiometry and stereochemistry of the complexes are discussed in relation to the basicity and π-bonding properties of the ligands.