Oxovanadium(IV) complexes with unsymmetrical macrocyclic ligands derived from o-bromoaniline, alpha- or beta-diketones and primary diamines

A new series of N-4-donor unsymmetrical oxovanadium(IV) complexes of type [ VO(mac)]SO4 ( mac = macrocyclic ligands derived from o-bromoaniline, alpha -or beta -diketone and aliphatic diamines e.g. ethylenediamine or 1,3-propy lenediamine) have been prepared by template synthesis. Tentative structures of the complexes have been proposed on the basis of elemental analysis, el ectrical conductance, magnetic moment and spectral (IR, electronic and EPR) data. The X-band EPR spectra of all the complexes have been recorded at ro om temperature and at liquid N-2 temperature. The room temperature EPR spec tra do not show anisotropy because of rapid tumbling of molecules in soluti on. The spectral studies support square-pyramidal geometry for the vanadium (IV) complexes.