DFT study of the Jahn-Teller effect in Cu(II) chelate complexes

Density functional theory (DFT) in conjunction with the intrinsic distortion path (IDP) is employed to study the Jahn-Teller (JT) effect in all four diastereoisomers of tris(ethylenediamine)copper(II) ([Cu(en)3]2+) and tris(ethyleneglycol)copper(II) ([Cu(eg)3]2+) complexes. As a consequence of the JT effect all the isomers tetragonally elongate to the C2 configurations. Although there are energy differences between the isomers of [Cu(en)3]2+, almost equal JT parameters suggest that chelate ring conformation does not have affect on the JT distortion. In a case of [Cu(eg)3]2+ JT effect causes additional hydrogen bond formation and these two effects define the overall geometry of isomers.