Osmium complexes thiourea

Other sulphur-containing organic reagents for determination of osmium are, 2,3-quinoxalinedithiol (e = 1.710" ) [89], Bismuthiol II [90], rubeanic acid [91], and dithizone (complex formed at 80°C in alkaline solution, then extracted into CHCI3, e = 3.M0 at 360 nm) [92], The second-order derivative spectrum of the Os-thiourea complex has been used for determining Os in the presence of Ru [42a],... 

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

It appears that the main reaction product of OsO with thiourea is [Os(thio)s], together with formamidine disulfide, via initial formation of [Os02thio4]. The earlier-reported species [Os(thio)j](OH)Cl3 is likely to have contained the osmium(III) species. Salts of [Os(thio)< ] with [Cr(NH3)2(SCN)4] and [Cr(SCN)5] have been isolated using OSO4, thiourea and the complex anion in HC1. [Os(thio) ](SnCl3)2Cl has been reported ESCA data on [Os(thio)j]Cl3 have been given. 

Recently, Takeda et al. (2007) and Minowa et al. (2007) introduced a complex RNAA procedure for the determination of trace siderophil elements and REEs in rock and meteorite samples. After irradiation, samples were subjected to alkaline oxidative fusion. Osmium and Ru were removed sequentially by evaporation and the remaining siderophil elements were retained on the chelating resin SRAFION NMRR REEs, Au, and Pt, and finally. Re and Ir were sequentially stripped from the column with 0.05 mol/1 HCl, 5% thiourea, and 7 mol/1 NH4OH, respectively. Although chemical yields determined by the reactivation method widely varied, the method seems to be promising for the sensitive determination of several PGEs (Ru, Os), Re, and lanthanides. 

Os3(GO)ii(NGMe) reacts with thiols, forming (/x-H)Os3(GO)io(/x-SR) clusters through the intermediacy of Os3(GO)ii(HSR) complexes where the thiol is bound to one osmium atom through the S-H bond. " Thioureas also react with triosmium dodecacarbonyl ... 

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