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

Citations Over TimeTop 17% of 2011 papers

Abstract

Valence tautomeric compounds involving nondixolene-type ligands are rare. The triple-helicate copper(II) complex [Cu(II)(2)(L)(3)](ClO(4))(4)·3CH(3)CN (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(•+) radical with concomitant reduction of the Cu(II) center to Cu(I), as shown by the equilibrium [Cu(II)Cu(I)L(•+)L(2)](4+) ⇄ [Cu(II)(2)L(3)](4+).

Related Papers

• → Azo-hydrazone tautomerism of hydroxyazo compounds—a review(1982)140 cited
• → Identification, classification and relative stability of tautomers in the cambridge structural database(2010)68 cited
• → Direct demonstration of tautomeric nature of 4‐bromo‐3(5)‐methylpyrazoles(2022)4 cited
• → The tautomerism of 6-hydroxy-, 6-amino- and 6-acylamino-7-azaindolines(1966)19 cited
• → Studies on the Tautomerism of 2-Anilinopyridine and Related Heterocycles. II. 2-Anilino-5-nitropyridine and 2-Anilinopyrimidine(1980)9 cited