Preparation and Circular Dichroism Spectra of P-mer (N)-trans (0)(8-Amino-3, 6-diazaoctanoato) (L-phenylalaninato)cobalt (Ill) Diastereo i s o m e r s t

In order to isolate the diastereoisomers (abbreviated as isomers below) in [Co(adao)(L-phe)]+(adao: -OOCCH2NH2(CH2)2NH(CH2)2NH2; L-phe: C6H5CH2CH(NH2)C00-) and to clarify their structures, the liquid chromatographic separation was carried out on the reaction products from β-mer(N)-[Co(adao)Cl(H2O)]ClO4 and L-phenylalaninate ion. Two isomers were successfully isolated as the crystals from two eluates (EI and EII). The elemental analyses indicated that the crystals had the compositions of [Co(adao)(L-phe)]X[sm middot]nH2O { (X, n) = (I, 2), (ClO4, 1)}, respectively. Their absorption spectra in aqueous solution showed that both crystals are trans(O) isomers. As shown in Fig., 1, it is apparent that adao in the trans(O)isomers coordinates with the β-mer(N) coordination mode. By using the circular dichroism (CD) spectra of two isomers, the configurational effective CD curves and the vicinal effective CD curve of L-phenylalanine were calculated. On the basis of the configurational CD curve for the trans(O) isomer from EI, it has been deduced that this isomer has the δ(δδδδ)-β-mer(N)-trans(O) structure. Therefore, the isomer from Elf has been assigned to the δ(δδδδ)-β-mer(N)-trans(O) one.