Studies of the circular dichroism of bisdiamine complexes of cobalt(III).

Abstract

Circular dichroism spectra are reported for cis-bis-diamine d 6 metal complexes with C 4v symmetry, of the type cis-[Co(en) 2(NH 3)(X)] n+. An empirical molecular orbital treatment is used to predict and assign the circular dichroism transitions associated with the d→ d absorption bands. The theory is extended to the trans-bisdiamine and cis-bisdiamine metal complexes with D 4hand C 2 symmetry, respectively. The band splittings of the d→ d transitions of the trans-bisdiamine complexes are twice those of the cis-bisdiamine complexes with C 4v symmetry. Linear relationships are found experimentally between the frequencies of the circular dichroism components of the visible absorption bands and δΔ, the empirical molecular orbital parameter, which has sigma and pi components, and is the digonal perturbation due to the ligands.