The crystal structure analysis of the chloroform adduct of NN′-ethylenebis(salicylideneiminato)copper(II) has revealed that the red crystals are monoclinic, a= 13·42, b= 7·54, c= 17·88 Å, β= 96·0°, space group P21/c. The copper complex exists as a centrosymmetric dimer, with axial bonds of length 2·79 Å from the copper of one molecule to a ligand oxygen of the other. The chloroform is not associated with the copper atom, but forms a hydrogen bond to the ligand oxygen atom not involved in this dimerisation bond. By comparison with related structures, it is demonstrated that such hydrogen bonding may influence the ability of the copper atom to increase its co-ordination number above four.
