Synthesis, structure and properties of monomeric complexes obtained from the cleavage of a (μ-oxo)bis(μ-carboxylato) diruthenium(III) core

Abstract

Reaction of [Ru 2O(O 2CR) 2(MeCN) 4(PPh 3) 2](ClO 4) 2 ( 1) with 1,2-diaminoethane (en) in MeOHH 2O yielded a mixture of products from which a diamagnetic ruthenium(II) complex [Ru(MeCN)(en) 2(PPh 3)](ClO 4) 2 ( 2) and a paramagnetic ruthenium(III) species [Ru(O 2CR)(en) 2(PPh 3)](BPh 4) 2 ( 3) (R = Ph, a>; C 6H 4-p-Me, b; C 6H 4-p-OMe, c) were isolated and characterized. The crystal structure of complex 2, obtained by X-ray diffraction analysis, shows a cis arrangement of the unidentate ligands in this octahedral complex. Complex 3 displays an axial EPR spectrum. Complex 2 undergoes two successive irreversible metal-centred one-electron oxidation processes at 1.13 and 1.33 V vs SCE in MeCN-0.1 M [NBU 4 n]ClO 4 at 50 mV s −1. The mechanistic aspects of the core cleavage reactions in 1 are discussed.