Osmium compounds Os

The same behavior reported for the Mo complexes XXI and XXII was also observed by Matyjaszewski for the osmium compounds Os Cl2(PPh3)3 (XLIII) and Cp Os Br(PtPr3)2 (XLIV) (Figure 32). Complex XLIII ensures good control by ATRP in the bulk polymerization of styrene, MMA, and BA at... 

Organic imide ligands have also been used to stabilize high oxidation states. The best example of this is the osmium(VIII) compound Os(NBul)4, which has a distorted tetrahedral OsN4 core (N—Os—N 104.6-111.9° Os—N 1.750 A) [194],... 

Fig. 7.54 Mosshauer spectra of osmium compounds obtained at 4.2 K with 69.6 keV (a) and 36.2 keV (b) transitions of Os with a source of Ir in iridium metal (from [258])...

Table 7.9 Summary of the results obtained from the Mossbauer spectra of the 36.2 and 69.6 keV y-rays of Os in absorbers of various osmium compounds containing d mg of is the full experimental line width at half maximum, 5 the isomer shift with respect to the source of Ir metal. 

However, when osmium atoms are co-condensed with a mixture of benzene and 2-methylpropane only trace amounts of [Os (Tj -CgHg) (TjG-CgHg) ] can be detected in the reaction mixture. More importantly, the tri-nuclear compound [ Os (Tl -CgHg) 3 ( j2-H) 3 ( j3- (CH2) 3CH) ] can be isolated (5) (Figure 8) (29). Co-condensation of osmium... 

We have previously seen examples of the carbon-like formulas of mononuclear and dinuclear osmium compounds, namely the methane-like tetrahydride (4.50c), ethylene-like H20s=CH2 (4.51c) and H2Os = OsH2 (Table 4.15), acetylenelike HOs = CH (4.54c) and HOs = OsH (Table 4.15), allene-like H2C = Os = CH2 (4.55a), and so forth. While the coordination numbers and Lewis-like formulas are formally analogous, the actual structures of Os and C species may be quite similar (e.g., the Td structures of OsfL and CH4) or dissimilar (e.g the strongly bent Cs structure of H20s = CH2 [Fig. 4.13(c)] versus the planar D2h structure of H2C = CH2). 

Examples of the osmium and iridium complexes are Os(PPh3)2Cl(NO) and Ir(PPh3)3(NO), respectively [216]. The osmium compound gave, on reaction with HC1, the first characterized complex with the feature of an N-coordinated HNO, Os(PPh3)2Cl2(HNO), which was confirmed by X-ray crystallography. On the other hand, the nitrosylated iridium compound gave the hydroxylamine complex [216]. 

Os (Tp)(OTf)(Cl)2] can abstract a nitrogen atom from MeCN upon heating to give the osmium nitrido compound [Os (N)(Tp)(Cl)2] (Equation (75)). The suggested mechanism is hydrolysis at Os followed by redox disproportionation to Os and Os ... 

Osmium tetroxide can be obtained from almost any osmium compound and a strong enough oxidant. X-ray structural studies show that solid Os04 contains a slightly distorted tetrahedron (O—Os—O angle of 106.7(4)° and 110.7(3)°, two Os=0 distances of 1.684(7) A, and two 1.710(7) A) (319), whereas electron diffraction data on the vapor show that the vapor contains regular tetrahedral molecules with... 

OSO4 is obtained on oxidation of any osmium compound or by direct synthesis at 300-800°C from the elements [50], Its solubility in CCI4 and volatility make it easy to purify it forms pale yellow crystals (m.p. 40.46°C, b.p. 131°C). Like RUO4 it forms tetrahedral molecules with Os-O 1.684-1.710 A, O—Os—O 106.7-110.7° in the solid state Os-O 1.711A in the gas phase [51], It is soluble in water as well as in CCI4 and is very toxic (TLV 2.5 ppm), affecting the eyes. (Its use as a biological stain involves its reaction with tissue.)... 

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