Reporting a Unique Example of Electronic Bistability Observed in the Form of Valence Tautomerism with a Copper(II) Helicate of a Redox-Active Nitrogenous Heterocyclic Ligand

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• 作者：Nabanita Kundu ; Manoranjan Maity ; Pabitra Baran Chatterjee ; Simon J. Teat ; Akira Endo ; Muktimoy Chaudhury
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：December 21, 2011
• 年：2011
• 卷：133
• 期：50
• 页码：20104-20107
• 全文大小：789K
• 年卷期：v.133,no.50(December 21, 2011)
• ISSN：1520-5126

文摘

Valence tautomeric compounds involving nondixolene-type ligands are rare. The triple-helicate copper(II) complex [Cu^II₂(L)₃](ClO₄)₄路3CH₃CN (1) containing a redox-active N-heterocyclic ligand (L) has been prepared and displays VT equilibrium in solution, as established by electronic spectroscopy, electron paramagnetic resonance spectroscopy, and cyclic and differential pulse voltammetry carried out at variable temperatures. The process involves intramolecular transfer of an electron from one of the L ligands to a copper(II) center, leading to the oxidation of L to an L^鈥? radical with concomitant reduction of the Cu^II center to Cu^I, as shown by the equilibrium [Cu^IICu^IL^鈥?L₂]⁴⁺ [Cu^II₂L₃]⁴⁺.