Thioether complexes, osmium

No sulfoxide complexes of osmium have been reported. Unsymmetri-cal dialkyl sulfoxides have been utilized in extraction studies, and methyl-4,8-dimethylnonyl sulfoxide has found application in the extraction of iron (266). Extraction of ruthenium from hydrochloric acid solutions by sulfoxides has been studied (470) and comparisons of sul-fones, sulfoxides, and thioethers as extractants for nitrosoruthenium species reported (441, 443). Similar studies on the extraction of nitro-soosmium species have been reported (442). 

Apparently, soft sulfur ligands alone cannot stabilize Ru or Os . The existing thioether, thiolato, and sulfide complexes of ruthenium(VI) and osmium(VI) are associated with either the 0x0 or the nitrido ligand and they have been discussed in the previous sections. 

Only one dialkyl sulfide complex has been reported,/ac-Os(SEt2)3Cl3, but recently a number of osmium-(III), -(IV) and -(VI) complexes of chelating thioethers have been prepared. There is also only one DMSO complex, Os(DMSO)3Cl3 (see p. 602). 

A Cr(VI) sulfoxide complex has been postulated after interaction of [CrOjtClj] with MejSO (385), but the complex was uncharacterized as it was excessively unstable. It was observed that hydrolysis of the product led to the formation of dimethyl sulfone. The action of hydrogen peroxide on mesityl ferrocencyl sulfide in basic media yields both mesityl ferrocenyl sulfoxide (21%) and the corresponding sulfone (62%) via a reaction similar to the Smiles rearrangement (165). Catalytic air oxidation of sulfoxides by rhodium and iridium complexes has been observed. Rhodium(III) and iridium(III) chlorides are catalyst percursors for this reaction, but ruthenium(III), osmium(III), and palladium(II) chlorides are not (273). The metal complex and sulfoxide are dissolved in hot propan-2-ol/water (9 1) and the solution purged with air to achieve oxidation. The metal is recovered as a noncrystalline, but still catalytically active, material after reaction (272). The most active precursor was [IrHClj(S-Me2SO)3], and it was observed that alkyl sulfoxides oxidize more readily than aryl sulfoxides, while thioethers are not oxidized as complex formation occurs. 

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