Circular dichroism spectra of asymmetric unidentate amine complexes of cobalt(III)

Abstract

The preparations of pentaamminecobalt(III) complexes of a series of asymmetric unidentate amines are reported. The circular dichroism spectra for the (S)-amines show negative Cotton effects under the ¹A_1g → ¹T_1g absorption band, which are somewhat solvent dependent but independent of temperature down to -190°C. The vicinal effect from 1- cyclohexylethylamine was comparable to that from analogous aromatic compounds, but the simpler alkyl derivatives were found to impose smaller rotational strengths on the d-d transitions. The lack of measurable c.d. in the visible region for tetraammine((S)-butane-1,3- diamine)cobalt(III) is reported and discussed in the light of the other studies.