MIXED-LIGAND COMPLEXES OF CHROMIUM(III) AND IRON(III) - SYNTHESIS ANDEVALUATION AS CATALYSTS FOR OXIDATION OF OLEFINS

The mixed ligand complexes Cr-III(dpa)(L)Cl and Fe-III(dpa)(L)(H2O)(x) Cl (where dpa = dipicolinic acid, L = ethylenediamine, 2,2-bipyridine or 1,10-phenanthroline, n = 1 or 2) were synthesized and characterized by elemental analysis and spectral, magnetic, conductance and electro chemical studies. The complexes were evaluated for their activity as c atalysts for the epoxidation of olefins. The chromium complexes cataly zed epoxidation of olefins, viz., norbornene, cis-cyclooctene, styrene and cyclohexene with iodosylbenzene, to give corresponding epoxides. Oxidation of cyclohexene gave allylic oxidation products besides the e poxide. The iron complexes were nearly inactive as epoxidation catalys ts under these conditions. Spectrophotometric and electrochemical meas urements were used to deduce the cause of low catalytic activity.