Conformational analysis of EDTA-type chromium(III) complexes with β-propionato metal chelate rings

Conformational analysis of the three geometrical isomers of (aqua)(ethylenediamine-tripropionato)chromium(III) has been performed with the Consistent Force Field (CFF) program. Four stable conformations were identified for trans(H2O,O) and trans(H2O,NH), and five stable conformations for trans(H2O,N′) geometrical isomer. Their structure and relative strain were analyzed and compared with the available experimental data. The conformer representing the global minimum (population 58% at 298 K) was found to match closely the X-ray structure of the trans(H2O,NH) isomer. The factors which determine the individual chelate ring conformations, and conformational transmission through the entire ligand system was elucidated, and a possible extension of this analysis to other EDTA-type complexes is indicated. [Copyright &y& Elsevier]