Mixed cobalt(III) complexes with aromatic amino acids and diamine. Part IV. Influence of noncovalent intra-and 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 alpha and beta proton coupling constant analysis. The effect of noncovalent intra- and interligand interactions on the population of rotamers in D20 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.

Mixed cobalt(III) complexes with aromatic amino acids and diamine. Part II. Synthesis and configuration of (1,2-diaminoethane)bis(L-tyrosinato)cobalt(III)complex diastereomers. The crystal structure of the delta-C1-cis(O) diastereomer.

In the reaction of trans-[CoCl2(en)2]+ with L-tyrosine all six theoretically possible diastereomers of the (1,2-diaminoethane)bis(L-tyrosinato)cobalt(III) complex were formed. The following five were isolated: gamma-trans(O); and gamma- and delta-C2-cis(O) and gamma- and delta-C1-cis(O) diastereomers, while the delta-trans(O) diastereomer was only detected in the corresponding eluate. Separation of the obtained diastereomers was performed by chromatography on a Dowex 1 x 4 column.