Cobalt(III) complexes containing carboxylate ligands

Abstract

The i.r. absorption spectra of a number of cobalt(III) compounds containing carboxylate ligands are reported. Compounds of the type [Co(en)CO₃]X have spectra of two distinct types. Deuteriation studies show that the spectral differences are in the vibrations of the ethylenediamine chelate ring. It is suggested that hydrogen bonding between the amine protons and the anion favours specific conformations of the ethylenediamine (en) rings in some compounds. The results suggest that in the phenanthroline compound, [Co(phen)₂CO₃]⁺, the C–O bond order has decreased in comparison with that in the bisethylenediamine-containing ion, which may indicate stronger M–O bonding.