Metal complexes of sulphur ligands. Part 10. Reaction of mer-trichlorotris(dimethylphenylphosphine)osmium(III) with dimethyldithiocarbamate, dimethyl- and diphenyl-phosphinodithioate, and O-ethyl dithiocarbonate ligands

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Abstract
Reactions of the complex mer-[OsCl3(PMe2Ph)3](1) with excess of [S–S]– ion (S–S–= S2CNMe2 –, S2PMe2 –S2 PPh2 –, or S2COEt) have been thoroughly studied. For [S2CNMe2]–, refluxing in methanol for 90 min gives a high yield of cis-[Os(PMe2Ph)2(S2CNMe2)2](2). whereas shaking in methanol gives mer-[OsCl(PMe2Ph)3 –(S2CNMe2)](3). Reaction of (3) with Na[S2CNMe2]·2H2O in refluxing ethanol gives (2) together with small amounts of fac-[OsCl(PMe2Ph)3(S2CNMe2)](5) and fac-[Os(OEt)(PMe2Ph)3(S2CNMe2)](6). whereas with K[S2COEt] these three complexes and cis-[Os(PMe2Ph)2(S2CNMe2)(S2COEt)](4) are formed. Similarly, for [S–S]-= S2PMe2 –or S2PPh2 –, reaction with (1) in refluxing ethanol gives cis-[Os(PMe2Ph)2(S2PR2)2][R-Me (7) or Ph (8)]. However, shaking in methanol gives paramagnetic mer-[OsCl2(PMe2Ph)3(S2PR2)][R = Me (9) or Ph (10)]. Recrystallisation of (9) from boiling benzene gives tans-[OsCl2(PMe2Ph)3(S2PMe2)]+(11), whereas prolonged standing in cold benzene gives a purple oil containing the cation [OsCl(PMe2Ph)3(S2PMe2)]+(12) together with (1) and brown crystalline mer-[OsCl(PMe2Ph)3(S2PMe2)](13). Carbonylation of (7) in refluxing ethanol in thepresenceof sulphur gives cis[OS(CO)(PMe2Ph)(S2PMe2)2](14) together with a brown oil containing PMe2PhS and a complex of probable formula [Os(CO)2(PMe2Ph)(S2PMe2)2](15). In the presence of PMe2Ph, carbonylation of (7) gives [Os(CO)(PMe2Ph)2(S2PMe2)2](16) whereas in cold CH2Cl2–C6H13 a different isomeric form of [Os(CO)(PMe2Ph)2(S2PMe2)2](17) is produced. In contrast, reaction of (1) with K[S2COEt] under all conditions gives only mer-[OsCl(PMe2Ph)3(S2COEt)](18). The complexes have been characterised by elemental analyses and mass, i.r., and n.m.r. spectroscopy (1H and 31P), and detailed mechanisms for the overall reaction and the carbonylation of (7) are postulated.

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