Complexes of cobalt(II) and nickel(II) halides with imidazole

Abstract

The preparation and spectral and magnetic properties are reported for complexes of cobalt(II) and nickel(II) halides with imidazole (lz). The compounds Iz₄NiX₂(X = Cl, Br, or l), lz₂NiX₂(X = Cl or Br), Iz NiX₂(X = Cl or Br), and lz CoCl₂ possess essentially octahedral structures whilst lz₂Nil₂, Iz Nil₂, lz₂CoX₂(X = Cl, Br, or l), and Iz CoX₂(X = Br or l) are pseudotetrahedral. The product of fusing a 4 : 1 mole ratio of imidazole and cobalt(II) chloride has been shown to be an equimolar mixture of Iz₆CoCl₂ and lz₂CoCl₂. The M–lz stretching vibration occurs at a higher frequency in these complexes than the M–pyridine vibration in the corresponding pyridine complexes. The ligand field parameter Dq appears to be less for imidazole than for pyridine.