Dimer species in dimethyl sulfoxide-water (80:20 w/w) solution of N,N'-bis(salicylideneimine)-m-phenylenediamine (H(2)sal-m-phen) and similar Schiff bases with Cu-II, Ni-II, Co-II and Zn-II. Crystal structure of [Co-2(sal-m-phen)(2)]center dot CHCl3

Potentiometric studies were carried out in dimethyl sulfoxide-water (80:20 w/w) at 25 degrees C and ionic strength 0.1 mol dm(-3) in NaClO4 for the Schiff bases H(2)sal-m-phen [N, N'-bis(salicylidene)-m-phenylenediamine], H(2)sal-2, 4-toluen [N, N'-bis(salicylidene)toluene-2,4-diamine] and H(2)sal-2, 6-toluen [N, N'-bis(salicylidene)toluene-2, 6-diamine] and their complexes with Cu-II, Ni-II, Co-II and Zn-II. These studies have shown that monomer, dimer, ligand:metal ratio 2:1 and 1:2 complex species are found. The first reported stability constants for these systems have been determined. The molecular structure of the complex [Co-2(sal-m-phen)(2)].CHCl3 has been determined by single-crystal X-ray analysis. It consists of dimeric centrosymmetric units, with the two bis(salicylideneiminato)-cobalt(II) residues bridged by two m-phenylene groups and with a chloroform molecule associated with each dimer molecule. The co-ordination geometry around each cobalt(Ir)can be best described as a distorted tetrahedron. Variable-temperature magnetic susceptibility measurements for the solid complexes [Co-2(sal-m-phen)(2)].CHCl3, [Co-2(sal-2, 4-toluen)(2)].4H(2)O, [Co-2(sal-2, 6-toluen)(2)], [Ni-2(sal-m-phen)(2)].3H(2)O, [Ni-2(sal-2, 4-toluen)(2)].3H(2)O, [Ni-2(sal-2, 6-toluen)(2)], [Cu-2(sal-2, 4-toluen)(2)] and [Cu-2(sal-2, 6-toluen)(2)] revealed a weak intradimer antiferromagnetic interaction.