Formamidine disulfide, formation

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. 

The kinetics of the coherent synchronous reactions of HP decomposition and oxidation of pyridine derivatives has been reported. Regioselective oxidation of the pyridine derivatives were studied and conditions have been optimized for the production of 4-vinylpyridine, 4-vinylpyridine oxide, 2,2 -dipyridyl, and pyridine. A probable synchronized reaction mechanism has been suggested for the decomposition of HP and the free radical chain oxidation of pyridine derivatives. It is suggested that the hydroperoxy radical (H02-radical) plays a key role in this reaction mechanism. The activation energy has been calculated for the elementary steps of the dehydrogenation of 4-ethylpyridine. Oxidation of formamidine disulfide with HP in acidic medium results in the formation... 

Thiourea acts as a mild reductant (E° = 0.427 V) for transition metal complexes and is oxidized to formamidine disulfide. Thiourea is an excellent ligand for many metal ions, especially for those of the platinum metals.88 Therefore, in most of its redox reactions, thiourea acts simultaneously as a reductant and as a ligand. For example, OSO4 reacts with thiourea in sulfuric acid to form [Osfthiole] and formamidine disulfide.89 Addition of [NH4][Tc04] to a solution of thiourea in a mixture of ethanol and hydrochloric acid results in the formation of the homoleptic thiourea complex of technetium(in), [Tc(thio)6] ". An X-ray structure study of the isolated product, [Tc(thio)6]Cl3-4H20, has shown that the six thiourea ligands are S-bonded to the metal. 

Hydroxyl radicals, generated radiolytically in N2O, react with thiourea and tetram-ethylthiourea to afford a radical cation. Initially an adduct forms between thiourea (or tetramethylthiourea) and HO this is followed by loss of HO and reaction of the resulting monomeric radical cation with a molecule of thiourea (or tetramethylthiourea) affords the dimeric radical cation. In the bimolecular decay of the dimeric radical cation formamidine (or tetramethylformamidine) disulfide is formed. In basic solutions of thiourea (but not tetramethylthiourea), the formation of a dimeric radical anion, via neutralization of the dimeric radical cation and subsequent deprotonation of the neutral dimeric radical, is observed. The reactions of the dimeric radical cation with O2, superoxide radical, phenolate ion, and azide ion have also been studied. ... 

A related insertion into an 7V,lV -formamidine ligand has been reported carbon disulfide addition to [Pd(C6F5)2(ti -tolNCHNtol)] (tol = tolyl) resulting in formation of [Pd(C6Fs)2 S2CN(tol)CHNtol ] (Eq. 24) (200). 

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