Osmium tris

Osmium, quinuclidinetetraoxime-stereochemistry, 1,44 Osmium, tetrachloronitrido-tetraphenylarsenate stereochemistry, 1,44 Osmium, tris(l,l0-phenanthro1ine)-structure, 1, 64... 

Polymetallic complexes presenting directional energy migration are of much significance for the design of photochemical molecular devices. Large arrays of multiple photoactive and redox-active building blocks (of ruthenium- or osmium tris(bipyri-dine)-type for instance) have been constructed for such purposes [A. 10,8.25-8.27]. 

Reaction of dineopentylosmium dioxide with 2 equiv. of Ta(CHR)(CH2R)3 was reported to result in the formation of osmium dineopentylbisneopentylidene [269, 270]. Interconversion of the two isomeric forms [syn-anti and anti-anti) of this compound was postulated to proceed via an osmium tris(neopentyl)neo-pentylidene. So far, no reports on the ROMP activity of these complexes have been given. Similar to OsCls [271] and (p-cyrnene)OsCl2P(c-H,.) j [272], (/z-H)20s3(CO)io was reported to be active in the ROMP of NBE to yield all cis-poly-NBE [273]. 

Osmium, quinuclidinetetraoxime-stereochemistry, 44 Osmium, tetrachloronitrido-tetraphenylarsenate stereochemistry, 44 Osmium, tris( 1,10-phenanthroline) -structure, 64 Osmium(II) complexes polymerization electrochemistry, 488 Osmium(III) complexes magnetic behavior, 273 Osmium(lV) complexes magnetic behavior, 272 Osmium(V) complexes magnetic behavior, 272 Osmium(VI) complexes magnetic behavior, 272 Oxaloacetic acid decarboxylation metal complexes, 427 Oxamidoxime in gravimetry, 533 Oxidation-reduction potentials non-aqueous solvents, 27 Oxidation state nomenclature, 120 Oxidative addition reactions, 282 Oxidative dehydrogenation coordinated imines, 455 Oximes... 

The rate constants and activation parameters (including AV ) for electron self-exchange in the [Mn(CNC(CH)3)6]-"/ -" and [Mn(CNC6Hu)6] couples have been determined by Mn NMR line broadening in several pure and binary organic solvent systems. The values of A V cover a range of about 12 cm moP (-9 to -21 cm mol ) with no simple correlation with solvent parameters observed. A self-exchange rate constant of 0.7 0.4 M" s" has been calculated for the [Mn(edta)(H20)] and [Mn(cdta)(H20)] couples from the application of the Marcus relationship to outer-sphere cross-reactions with a variety of metal complexes in aqueous solution. Deviations from the correlation were observed for the nonadiabatic reactions with osmium tris(polypyridine) complexes. 

Lee W-Y, Majda M, Brezesinski G, Wittek M, Mobius D (1999) Structure and lateral electron hopping in osmium-tris-4,7-diphenylphenanthroline perchlorate monolayers at the air/water interface. J Phys Chem B 103(33) 6950-6956. doi 10.1021/jp991053-t... 

Osmium tris(dithiocarbamate) complexes [Os(S2CNR2)3] were only authentically detailed in the early 1980s (295,296). They can be prepared upon addition... 

Because osmium tetroxide is expensive, and its vapors are toxic, alternate methods have been explored for effecting vic-glycol formation. In the aliphatic series, olefins can be hydroxylated with hydrogen peroxide with the use of only a catalytic amount of osmium tetroxide. Anhydrous conditions are not necessary 30% hydrogen peroxide in acetone or acetone-ether is satisfactory. The intermediate osmate ester is presumably cleaved by peroxide to the glycol with regeneration of osmium tetroxide. When this reaction was tried on a A -steroid, the product isolated was the 20-ketone ... 

Many of the reactions already discussed for the preparation of bis-oxygenated pregnanes can also be used for the synthesis of 17,20,21-tris-oxygenated pregnanes by proper choice of substrate. Thus, reaction of a 17-vinyl-17-hydroxy steroid or a A -21-hydroxypregnene with osmium tetroxide will give the 17,20,21-triol, and the Stork reaction can be applied to 17a-hydroxy-20-keto steroids. 

Rhodium-on-carbon has also been found to bring about the formation of 2,2 -biquinoline from quinoline, the yield and the percentage conversion being similar to that obtained with palladium-on-carbon. On the other hand, rhodium-on-carbon failed to produce 2,2 -bipyridine from pyridine, and it has not yet been tried with other bases. Experiments with carbon-supported catalysts prepared from ruthenium, osmium, iridium, and platinum have shown that none of these metals is capable of bringing about the formation of 2,2 -biquinoline from quinoline under the conditions used with palladium and rhodium. ... 

There is a wide range of diketonates, such as Ru(acac)3, with octahedral coordination [133b] (they do not seem, however, to be oxidized to the +4 state this is possible with osmium) similarly several salts of the tris(oxalato) complex Ru(C204)3 have been isolated. 

Oxidation of Coordinated Diimine Ligands in Basic Solutions of Tris( diimine )iron(III),-ruthenium(III), and -osmium(III)... 

The rate of oxidation of tris(2,2 -bipyridine)osmium(II) by octacyanomo-lybdate(V)... 

Antimony, arsenic, selenium, tellurium, iridium, iron, molybdenum, osmium, potassium, rhodium, tungsten (and when primed with charcoal,) aluminium, copper, lead, magnesium, silver, tin, zinc. Interaction of lithium or calcium with chlorine tri- or penta-fluorides is hypergolic and particularly energetic. 

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... 

Homogeneous Processes with Tris-phenanthroline Metal(III) Oxidants. The rates of electron transfer for the oxidation of these organometal and alkyl radical donors (hereafter designated generically as RM and R, respectively, for convenience) by a series of tris-phenanthroline complexes ML33+ of iron(III), ruthe-nium(III), and osmium(III) will be considered initially, since they have been previously established by Sutin and others as outer-sphere oxidants (5). 

The parent carbonyls, M COlu (M = Ru, Os), have not been isolated, but the related hydrides H2M4(CO)13 and HJVtjCCO) have been prepared for both ruthenium and osmium by direct reaction of the tri-nuclear carbonyl with hydrogen or water (see Section III,C) (82, 86). 

Figure 6.17. Phthalocyanine, naphrhalocyanine, Bodipy , and Tris(bipyridyl) osmium infrared fluorophores.

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