Infrared solvent shift studies. I. Acetylacetonates of some trivalent transition metals

Solvent shift studies of MIII acetylacetonates where M = Co, Cr, Fe and Mn are reported in the 1700-1250 cm-1 region in about 20 solvents. Definitive assignments are made on fundamental C=O and C=C=C stretching vibrations. New solid bands are reported; these are probably due to combination bands, overtones, and ligand-crystal field effects. The possibility of Jahn-Teller effects, Fermi resonance, and the degree of π-electron delocalization in the chelate rings are discussed.