Interaction of the polyfunctional 2-mercaptonicotinic acid with the ruthenium(III)-edta complex

摘要

Ruthenium(III)-edta reacts with the 2-mercaptonicotinic ligand in aqueous solution yielding a red product (lambda(max) = 530 nm) coordinated at the S atom. This species undergoes deprotonation with an apparent pK(a) = 3.80, generating a blue complex in which the ligand is (S,N) bidentate. In the presence of two times excess of ruthenium(III)-edta a binuclear species is formed, involving two bidentate (N,S) and (S,O) coordination modes for the bridging ligand. The corresponding:mixed-valence species exhibits a strong intervalence band at 8000 cm(-1), involving an electronic coupling energy of 990 cm(-1). An extensive investigation is reported for the complexes, based on kinetics, cyclic voltammetry and spectroelectrochemistry. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 13]