Correlations between chirality and circular dichroism among trans-diacidotetra-amines of cobalt(III)

Conformational studies of metal chelates. II. Stereochemistry and conformational analysis of the cobalt(III) complexes of 4,7-diaza-5(R)-methyl-1,10-decanediamine

“…The CD spectrum of the trans isomer has been recorded and reported earlier. 25 On the basis of the correlations between the chelate ring conformations, the secondary amine configurations, and the signs of the A2 and Ea bands in the CD spectrum, which we proposed earlier,25 the trans complex was assigned the absolute configuration depicted in Figure 1 which is analogous to that of the 3.2.3. complex whose structure has since been determined. 26 In order to confirm this assignment for the 3.2'.3.…”

“…A comparison of the CD spectra of their trans complex and our trans-SW complex showed that the curves are almost superimposable. 25,28,31 This implies that the complexes have the same configurations. Since we know the configuration of the 3.2'.3.…”

Importance of donor atom distortions. Crystal structure, absolute configuration, and optical activity of (-)589-trans-dichloro(1,10-diamino-4,7-diazadecane)cobalt(III) nitrate

“…A recent study27 of complexes of 5-(R)-methyl-1,10-diamino-4,7-diazadecane, applying the hexadecant rule, concluded that the sign of the 'Eg band can be correlated with the ring chirality, while the sign of the 'A2g band does not always correlate with that predicted by the sector rule.20 An empirical correlation was noticed, however, with the chirality of the asymmetric, secondary nitrogen atoms. 27 We conclude therefore, that distortions of the donor atoms from an ideal octahedral geometry may give rise to additional sources of dissymmetry. Such sources may contribute markedly to the sign of the circular dichroism, especially in complexes where the prime sources of dissymmetry are either conformational or vicinal in origin.…”