A Quantum Chemical Study of Bis-(iminoquinonephenolate) Zn(II) Complexes

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• 作者：Andrey G. Starikov ; Vladimir I. Minkin ; Ruslan M. Minyaev ; Vitaliy V. Koval
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：July 29, 2010
• 年：2010
• 卷：114
• 期：29
• 页码：7780-7785
• 全文大小：317K
• 年卷期：v.114,no.29(July 29, 2010)
• ISSN：1520-5215

文摘

A computational DFT B3LYP*/6-311++G(d,p) study performed on bis-(iminoquinonephenolate) Zn(II) complex [Zn^II(C₁₂H₈NO₂)₂] has revealed a previously unexplored mechanism for valence tautomerism inherent in transition metal complexes with redox active (noninnocent) ligands. The occurrence of energy-close isomeric forms of the complex and their low energy barrier interconversion is caused not by the intramolecular electron transfer (IET) between the metal and ligand frontier orbitals, but the intersystem conversion within a redox active ligand without involvement of a metal center. This mechanism gives a new insight into the origin of the previously experimentally studied isomeric forms of bis-(iminoquinonephenolate) Zn(II) complexes that must be assigned to [Zn^II(¹L⁻¹)₂] (8) and [Zn^II(¹L⁻¹)(³L⁻¹)] (9) structures. The spin-forbidden transition between the two forms of the complex proceeds via a minimal energy crossing point (MECP) corresponding to the energy barrier of 8.9 kcal mol⁻¹ for the 9 → 8 transformation in the gas phase.