Osmium, tris structure

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

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... 

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... 

In [59] the authors reported the structure of a tri-osmium complex containing a hydride and clearly stated that a low temperature X-ray diffraction experiment would not be useful to locate the hydride if an accurate absorption correction is not carried out. Curiously, a few years before they had contacted Prof A. Sironi and myself at the University of Milan proposing a low temperature data collection on that compound, with the purpose of locating the not so clearly visible hydride. As evident from [59], we were able to convince them on the real problems connected with the location of hydrogens close to heavy metals. 

Reaction of 0s04 with catechol or substituted catechols Rcat in chloroform yields the deep blue diamagnetic Os(Rcat)3 species (Rcat = catechol, 4-rerf-octyl-, 4-terr-butyl-, 3,5-di-ferf-butyl-catech-ol).486 X-Ray crystal structures of Os(cat)3 and of the tris complex with 3,5-di-terf-butylcatechol show these to have D3 symmetry the Os—O distances fall within the range 1.947 to 1.985 A (mean 1.960 A) and the C—O distances are between 1.30 and 1.35 A the catecholato (02C6H4 or 02C6H2) rings are essentially planar.666 For Os(cat)3, IR, Raman, HNMR and electrochemical data were obtained the latter showed two one-electron reversible reductions, presumably to [Os(cat)3] and [Os(cat)3]2-. The diamagnetism of these formally osmium(VI) species probably arises from the distortion from octahedral to Z>3 symmetry.486... 

As with permanganate oxidations, a-hydroxy ketones can be formed as side products. In some cases, structural features make the osmium complex relatively unstable, and in an aqueous medium it can react with water to give a hydroxy-hydrate, which is then converted to an a-keto alcohol. Sharpless et al. developed a procedure that used tert-butyl hydroperoxide with a catalytic amount of osmium tetroxide,367 in the presence of tetraethylammonium hydroxide (EtqN" " OH ). The procedure gave improved yields of the cis-diol and a little a-hydroxyketone, as shown in the conversion of oct-(4 )-ene to a mixture of 258 and 259 in 73% yield. This method is more reliable for oxidation of tri- and tetrasubstituted alkenes than the Upjohn procedure. The reaction was not suitable for base sensitive alkenes, but later work showed that changing the solvent to acetone allowed the use of tetraethylammonium acetate (Et4NOAc) 68 for the hydroxylation of sensitive alkenes such as ethyl crotonate. 

Coupling of ruthenium or osmium polyazine light absorbers to rhodium has been investigated in some detail. Most of these systems include bis(triden-tate) or tris(bidentate) coordination on Rh(III), impeding reactivity at the rhodium site following photoreduction of rhodium. This structural motif has... 

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