Condensation reactions of tetracyanoethylene and its monoanion promoted by Lewis acids: synthesis and crystal, molecular, and electronic structure of a novel heterocycle, the 2,3,6,7-tetracyano-5-(tricyanoethenylimino)-3H-1,4,7b-triazabenzo[i,j]pentalenide ion

Abstract

From the condensation reaction of tetracyanoethylene (C₆N₄, TCNE) with its radical monoanion (C₆N₄˙^–) promoted by a Lewis acid [ZnCl₂, AlCl₃, or V(bpy)₃⁺²], a novel heterocyclic carbanion (C₁₇N₁₁^–) has been synthesized and characterized by X-ray, ¹³C NMR, IR, and UV spectroscopy and cyclic voltammetry measurements. The crystal and molecular structure of the title anion has been determined for the tetraphenylarsonium salt, and its electronic structure and the mechanism of formation are discussed.