Conformational analyses of the isomers of the [Co{(±)pm}n(en)₃₋n]³⁺ systems: a reinvestigation (en=ethane-1,2-diamine; pn=propane-1,2-diamine; n=0—3)

A molecular mechanics study of the isomers of [Co(pn)n(en)₃₋n]³⁺ (n=0-3) is reported. The MM2 force field has been parameterized for cobalt(III) amine complexes and the complete set of stereoisomers of the title complexes has been modelled. Detailed structural and thermodynamic comparisons are made with previous calculations on these systems and with experimental data. Structural details were satisfactorily modelled by MM2, and the correspondence between the calculated isomer ratios and those observed experimentally is excellent. The significance of statistical factors in thermodynamic comparisons of this type is discussed