Electrochemical and structural studies of one-dimensional copper charge transfer complexes.

Abstract

The electrochemistry of solid electrodes of charge transfer complexes of tetracyanoquinodimethane (TCNQ) and copper complexes with nitrogen containing chelates, such and dipyridylamine (dpaH), bipyridyl (bpy) and 1,10-dimethyl-2,9-phenanthroline (dmp), has been investigated with cyclic voltammetry. Pressed pellet electrodes of these complexes exhibit a broad electrochemically stable region. The oxidative and reductive breakdown reactions involve solid state reactions into the bulk electrode. These materials also act as electron mediators for glucose oxidation in glucose oxidase modified electrodes. The structure of the model compound, copper(I)(dpaH)₂Cl has been determined to have a distorted tetrahedral coordination sphere. The electrochemistry of solid electrodes of charge transfer complexes of tetrathiafulvalene (TTF) with copper chloride and copper bromide has been investigated with cyclic voltammetry. Pressed pellet electrodes do not exhibit a broad stable region, as do the TCNQ complexes. A preliminary structure of the organic part of tetramethyltetraselenafulvalene copper chloride has been determined from the solution of the Patterson function and exhibits a displacive modulation with a repeat unit of seven TMTSF molecules. (TTF)(SCN)₀ͺ₆₆ and (TTF)Cu(SCN)₂ have been investigated by infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. (TTF)(SCN)₀ͺ₆₆ crystallized in a tetragonal space group with a disordered column of thiocyanate anions. (TTF)Cu(SCN)₂ is an insulator with a two-dimensional network of Cu(SCN)₂⁻ ions. X-ray crystal structures of four compounds prepared in association with copper complex chemistry have been determined; (1) 5,5'-dibromo-2,2'-bithiophene, (2) 3,5,5'-tribromo-2,2'-bithiophene, (3) Cu(dmp)(CN)₂ ⁻ · Bu₄N⁺ and (4) the 1:2 adduct of dimercaptosuccinic acid and dimethylformamide.