Quantum chemical studies on the enantiomerization mechanism of several [Zn(py)3(tach)]2+ derivatives

Abstract

The enantiomerization mechanism of the trigonal-prismatic [Zn(py)₃(tach)]²⁺ complex and several derivatives has been studied by applying DFT calculations (B3LYP/LANL2DZp). The enantiomerization pathways of [Zn(py₃tach-X)]²⁺ (X = C, Si, Ge, N, P, As, O, S and Se) start from a distorted trigonal-prismatic C₃ symmetric ground state via an ideal trigonal-prismatic C_3v structure to end up in a C₃′ symmetric image of the ground state. The activation energy and structural data of the complexes depend on electronic and steric factors. The activation barriers of the complexes decrease in the order [Zn(py₃tach-Ge)]²⁺ > [Zn(py₃tach-Si)]²⁺ > [Zn(py₃tach-As)]²⁺ > [Zn(py₃tach-Se)]²⁺ > [Zn(py₃tach-P)]²⁺ > [Zn(py₃tach-S)]²⁺ > [Zn(py₃tach-C)]²⁺ > [Zn(py₃tach-N)]²⁺ > [Zn(py₃tach-O)]²⁺.