REVERSIBLE DIMERIZATION OF 3,3',5,5',-TETRAMETHYL-2,2'-BITHIOPHENE CATIONS

Cyclic voltammetric measurements at different temperatures, concentrat ions and scan rates give evidence for the reversible dimerization of 3 ,3',5,5',tetramethyl-2,2'-bithiophene radical cations. The analysis of the experimental data confirm the mechanistic concept of a RR dimeriz ation. The rate constants and equilibrium constants were determined fr om working curves and digital simulations. The reaction enthalpy is -6 0 kJ mol(-1). The weak temperature dependence of the rate constants fo r the dimerization results in values of the activation enthalpy that i s close to zero or even negative. (C) 1997 Elsevier Science S.A.