Three alkaline-earth metal complexes with 3D networks constructed from a 7,7,8,8-tetracyanoquinodimethaneligand: synthesis, structure and electrochemical properties

Abstract

Three new 7,7,8,8-tetracyanoquinodimethane (TCNQ) alkaline-earth metal complexes, namely {[M₂(TCNQ)₃(H₂O)₆]·TCNQ}_n (M = Ca (1), Sr (2) and Ba (3)) have been synthesized by salt elimination reactions. X-ray crystallographic analysis reveals that complexes 1, 2 and 3 are isomorphic featuring a unique 3D structure. Cyclic and differential pulse voltammograms for complexes 1–3 show a reversible one-electron oxidation and a reversible one-electron reduction within the electrochemical window of CH₃CN. Their electrochemical HOMO–LUMO gap and reversibility are examined.