The oxidative conversion of the N,S-bridged complexes [{RhLL′(μ-X)}2] to [(RhLL′)3(μ-X)2]+ (X = mt or taz): a comparison with the oxidation of N,N-bridged analogues

Abstract

The structures of [{RhLL′(μ-X)}₂] [LL′ = cod, (CO)₂, (CO)(PPh₃) or {P(OPh)₃}₂; X = mt or taz], prepared from [{RhLL′(μ-Cl)}₂] and HX in the presence of NEt₃, depend on the auxiliary ligands LL′. The head-to-tail arrangement of the two N,S-bridges is accompanied by a rhodium-eclipsed conformation for the majority but the most hindered complex, [{Rh[P(OPh)₃]₂(μ-taz)}₂], uniquely adopts a sulfur-eclipsed structure. The least hindered complex, [{Rh(CO)₂(μ-mt)}₂], shows intermolecular stacking of mt rings in the solid state. The complexes [{RhLL′(μ-X)}₂] are chemically oxidised to trinuclear cations, [(RhLL′)₃(μ-X)₂]⁺, most probably via reaction of one molecule of the dimer, in the sulfur-eclipsed form, with the fragment [RhLL′]⁺ formed by oxidative cleavage of a second.