Synthesis and spectral studies on mononuclear complexes of chromium(III) and manganese(II) with 12-membered tetradentate N2O2, N2S2 and N4 donor macrocyclic ligands

Complexes of Cr-III and Mn-II of general formula [Cr(L) X-2] X and [Mn(L) X-2] respectively were prepared from N2O2, N2S2 and N-4 donor macrocyclic ligands. The complexes have been characterized by elemental analysis, molar conductance measurements, spectral methods (i.r, mass, H-1-n.m.r, electronic spectra and e.p.r.) and magnetic measurements. The macrocyclic ligands have three different donating atom cavities, one with two unsaturated nitrogens and the other two have saturated nitrogen, oxygen and sulphur atoms. The effect of different donor atoms on the spectra and ligand field parameters is discussed. All the complexes show magnetic moments corresponding to a high-spin configuration. On the basis of spectral studies a six coordinated octahedral geometry may be assigned to these complexes.