1985 Volume 58 Issue 6 Pages 1807-1811
Four cobalt(III) complexes of the [Co(L-quadridentate-N,S,O2)(en)]+ type were prepared; where L-quadridentate-N,S,O2 denotes S-(carboxymethyl)-L-cysteinate(L-cmc), S-(2-carboxyethyl)-L-cysteinate(L-cec), S-(carboxymethyl)-L-homocysteinate(L-cmhc), or S-(2-carboxyethyl)-L-homocysteinate(L-cehc). Each complex was chromatographically separated into the quasi-enantiomeric isomers; ΛL-trans(O)-S(S) and ΔL-cis(O)-R(S) for the L-cmc, L-cmhc, and L-cehc complexes, and ΛL-trans(O)-R(S) and ΔL-cis(O)-S(S) for the L-cec one. These isomers were characterized from their absorption and 13C NMR spectra. The sterically strained ΔL-cis(O) isomers exhibited some significant CD spectral behavior in the first d-d absorption band region. The CD spectra are discussed in relation to the sizes of the S–N and S–O chelate rings joining the chiral sulfur atom in the L-quadridentate-N,S,O2 ligand.
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