Treatment of the dimer [Ru(OEP)]2 (1, OEP = dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin) with the thioethers n-decyl methyl sulfide (DecMS) and Ph2S yields the low-spin complexes Ru(OEP)L2, L = DecMS (2) and Ph2S (3). Complex 2 crystallizes in the triclinic system, space group P̅I, with a = 9.429 (3) Å, b = 14.198 (3) Å, c = 21.392 (5) Å, α = 87.68 (2)°, β = 79.19 (2)°, γ = 77.73 (2)° and Z = 2. Crystals of 3 are orthorhombic, space group Pbca, with a = 9.569 (1) A, b = 22.401 (1) A, c = 23.868 (2) A, and Z = 4. The average Ru-S distance of 2.37 Å in both complexes and relatively blue-shifted a bands in the visible spectrum (in the 525-nm region) suggest little π-back-bonding in the systems. Variable-temperature 1H NMR data reveal resolution of the protons of the axial thioether ligands (because of the porphyrin ring current), as well as the diastereotopic nature of the methylene protons of coordinated DecMS; the chirality at the coordinated sulfur atoms in 2 is R,S in the solid state, while in solution at ambient temperatures inversion at the sulfur is apparent, although axial ligand exchange is not observed. In contrast, 3 does undergo thioether exchange, almost certainly via a supposed five-coordinate intermediate that is also in equilibrium with 1: Preliminary data show that 2 catalyzes autoxidation of DecMS possibly via an outer-sphere process and in situ generation of H2O2, while 3 is ineffective for Ph2S oxidation because rapid decomposition to a Ru(IV) µ-oxo species occurs, probably via the five-coordinate intermediate and/or 1.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry