Synthesis and Configuration of New Isomers of the Bis(aminocarboxylato )carbonatocobaltate(III) Ion

In the reaction between potassium tricarbonatocobaltate(III) and the corresponding amino acid (glycine or ~-alanine) two new geometrical isomers of the bis(aminocarboxylato)carbonatocobaltate( III) ion have been obtained. In case of glycine, in addition to the previously described1- 3 cis(N), cis(O)-isomer, the corresponding cis(N), trans(O)-isomer was also obtained, whereas in the reaction with ~-alanine the trans(N), cis(O)-isomer was prepared. The configuration of the trans(N)-isomer was established using its electronic spectrum, whereas the configuration of the other two isomers was determined by means of PMR spectroscopy. In addition, the cis, cis-isomer was resolved into enantiomers by means of A - ( + )ss9-cis(N02), trans(N)-isomer of the bis(S-arginine)dinitrocobalt( III) ion. The absolute configuration of the tJ. - (-)589- -cis(N), cis(O)-isomer was assumed by comparing its CD spectrum with that of the A - ( + )58rcis(N), cis(O)-isomer of the carbonatobis-( S-valinato)cobaltate(III) ion

Mixed cobalt(III) complexes with aromatic amino acids and diamine. Part IV. Influence of noncovalent intraand interligand interactions on rotamer population of the S-phenylalaninato and S-tyrosinato side groups in (1,2-diaminoethane)bis(S-aminocarboxylato)cobalt(III) complexes

Rotamer population of S -tyrosinato and S -phenylalaninato ligands side groups in diastereomers of (1,2-diaminoethane) bis ( S -aminocarboxylato)cobalt(III) complexes is calculated by vicinal and proton coupling constant analysis. The effect of noncovalent intra- and interligand interactions on the population of rotamers in D 2 O solution is discussed. It has been established that in all the complexes investigated the most abundant is rotamer t , in which aromatic voluminous moiety and carboxylic group are in an anti position. In almost all complexes the lowest content is of rotamer g , in which these two groups are in the nearest position. Relatively high population of rotamer h in complex 5 tyr , in spite of high steric hindrances, is due to intra- and interligand NH interactions