Cyclic voltammetric studies on N,N-disubstituted N′-ferrocenoylthioureas and their transition metal complexes

The Fe(II)/Fe(III) redox potentials of N,N-disubstituted N'-ferrocenoylthioureas and the respective ferrocene-1,1'-dicarbonic acid-di- N,N-dialkyl-thioureids are shifted cathodically by complexation of Ni(II), Cu(II), Co(III), Mn(II), Pt(II) and Pd(II). The extent of the shift is more pronounced in the latter ligand class and reaches values up to -0.32 V. The N,N-disubstituted N'-ferrocenoylthioureas exhibit two redox processes in dichlormethane. A mechanistic scheme is proposed. Ferrocene-1,1'-dicarbonic acid-di-N,N-dialkylthioureids decompose after oxidation in dichlormethane. In contrast, complexes of both ligand types contain quasireversibly oxidisable ferrocene subunits. (C) 1998 Elsevier Science Ltd. All rights reserved.