Amino acid complexes of ruthenium: synthesis, characterization and cyclic voltammetric studies

Abstract

Reaction of α-amino acids (HL) with [Ru(PPh 3) 3Cl 2] in the presence of a base afforded a family of complexes of type [Ru(PPh 3) 2(L) 2]. These complexes are diamagnetic (low-spin d 6, S=0) and show ligand-field transitions in the visible region. 1H and 31P NMR spectra of the complexes indicate the presence of C 2 symmetry. Cyclic voltammetry on the [Ru(PPh 3) 2(L) 2] complexes show a reversible ruthenium(II)–ruthenium(III) oxidation in the range 0.30–0.42 V vs. SCE. An irreversible ruthenium(III)–ruthenium(IV) oxidation is also displayed by two complexes near 1.5 V vs. SCE.