Paramagnetic Resonance in Trivalent Transition Metal Complexes

Abstract

Paramagnetic‐resonance absorption has been observed in complexes of acetylacetone with the trivalent transition metals titanium, chromium, iron, molybdenum, and ruthenium. The symmetry of the field perturbing the metal ion is predominantly axial. For the complexes of Ti⁺³ and of Ru⁺³, the axial potential is negative. Energy‐level splittings by the ligand field and g factors were obtained for the various complexes. Resonance was also observed in complexes of trifluoroacetylacetone with chromium and iron and in the complex chromium (III) hexafluoroacetylacetonate. Resonance could not be detected in the complexes vanadium (III) acetylacetonate, manganese (III) acetylacetonate and ferric (III) hexafluoroacetylacetonate, although magnetic‐susceptibility measurements on the last two compounds indicated that they were paramagnetic.