Isomers chelate ring combinations

One of the most extensively studied systems is that of [Co(dien)2]3+ (Table 7.1). The mer- isomer is chiral (C2) because of the two possible orientations of the proton at the secondary nitrogen atomst38,39], the unsym-fac-vsoiasi is also chiral (C2) while the sym-fac-isomer is achiral (Q). For the five-membered chelate rings all possible combinations of S and X conformations (see Fig. 6.5 for the SIX nomenclature) have to be considered, leading to a total of 40 isomers and conformers (some conformers are calculated to be unstable and may therefore be neglected144,451). The calculated distribution is based on partition functions (Eqs. 7.1, 7.2) ... 

Co(trab)2]3+ (trab = 1,2,4-triaminobutane) has five isomers and a total of 16 con-formers (all nondegenerate combinations of chair and skew-boat of the six-mem-bered chelate rings Table 7.3 for the structures see Fig. 7.3). Two of the chromatographic signals of the three isomers A, B, C with optically pure trab were overlap-... 

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