Tuning of intramolecular electron transfer between Ru(ii) and the disulfide bond

Abstract

Reaction of 2,2′-dithiodipyridine (DTDP) with cis-Ru(bpy)₂Cl₂ (bpy = 2,2′-bipyridine) and cis-Ru(phen)₂Cl₂ (phen = 1,10-phenanthroline) respectively yields the dicationic species [Ru(bpy)₂(DTDP)]²⁺ and [Ru(phen)₂(DTDP)]²⁺ in which the S–S bond of DTDP remains intact. The S–S bond undergoes a reductive cleavage when DTDP is reacted with cis-Ru(bisox)₂Cl₂ (bisox = 4,4,4′,4′-tetramethyl-2,2′-bisoxazoline) under identical conditions to generate the monocationic species [Ru(bisox)₂(2-thiolatopyridine)]⁺. The intramolecular electron transfer between the metal and the S–S bond is found to be subtly controlled by the crystal field strength of the ancillary bidentate N-donor ligands.