METALLACYCLIC COMPLEXES .5. LIGAND PROPERTIES OF PLATINATHIETANE-3-OXIDE COMPLEXES AND THE SINGLE-CRYSTAL X-RAY STRUCTURE OF [PT(CH(COPH)S(O)CH(COPH))(PPH3)2.RHCL(CO)].CH2CL2.H2O

Treatment of the platinathietane-3-oxide complex [activatived Pt{CH(COPh)S(O)CH(COPh)}(PPh3)2] 1a with 1 mol equivalent of either [PdCl2(cod)] (cod = cycloocta-1,5-diene) or trans-[PdCl2(NCPh)2] and with 0.5 mol equivalents of [Rh2(mu-Cl)2(CO)4] affords the complexes [activatived Pt{CH(COPh)S(O)CH(COPh)}(PPh3)2.MCl(X)] (M = Pd, X = Cl; M = Rh, X = CO), which contain a five-membered activated M-S-C-C-O ring system, formed by co-ordination of the sulphoxide sulphur and the equatorial benzoyl oxygen atom to the metal M. The absence of reaction of 1a with the related labile platinum complexes [PtCl2(cod)] and cis-[PtCl2(NCPh)2] illustrates that the sulphur atom in 1a has relatively poor ligand properties. A single-crystal X-ray diffraction study has been carried out on [activatived Pt{CH(COPh)S(O)CH(COPh)}(PPh3)2.RhCl(CO)].CH2Cl2.H2O, 3. Crystals are triclinic, space group P1BAR, Z = 2, in a unit cell with lattice parameters a = 11.761 (17), b = 20.701 (18), c = 13.006 (16) angstrom, alpha = 102.8(3), beta = 124.7(3) and gamma = 88.4(2)-degrees. The structure was refined to R 0.0600 (R' 0.0559) for 5105 reflections having 7 < 2-theta < 54-degrees collected at room temperature. It bears a strong resemblance to that of complex 1a, but there are several differences which are discussed.