Osmium imine complexes

Like mthenium, amines coordinated to osmium in higher oxidation states such as Os(IV) ate readily deprotonated, as in [Os(en) (NHCH2CH2NH2)] [111614-75-6], This complex is subject to oxidative dehydrogenation to form an imine complex (105). An unusual Os(IV) hydride, [OsH2(en)2] [57345-94-5] has been isolated and characterized. The complexes of aromatic heterocycHc amines such as pyridine, bipytidine, phenanthroline, and terpyridine ate similar to those of mthenium. Examples include [Os(bipy )3 [23648-06-8], [Os(bipy)2acac] [47691-08-7],... 

Photoinduced and chemical oxidation of coordinated imines to amides in isomeric osmium(II) complexes of AT-arylpyridine-2-carboxaldimines has been studied by Ghosh and coworkers [34]. The complexes [Os(Br)2(Rimpy)2] (Scheme 1) were prepared and characterized structurally, indicating the pyridines of the two Rimpy ligands are trans to one another and the bromides are cis. Broadband photolysis of the complex in aerated acetonitrile resulted in oxidation of one Rimpy ligand to yield the RimOpy ligand and oxidation of the osmium to Os(III). The overall yield of the photochemical process is reported to be greater than 95%. The authors propose a mech-... 

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... 

Os(NH3)6] condenses with acetone in a redox-catalyzed coordinated ligand reaction, impelled by the Os(II)-imine intermediate being strongly stabilized by TT-bonding. Indeed one of the most distinctive features of the chemistry of osmium(II) is its unusually high tendency to 7r-bond. This has a large effect on reactivity, manifested in the various substitution and tautomerization reactions of [Os(NH3)5L] complexes discussed in this section. Kinetic parameters for reactions of the L = 17 -arene series have been conveniently assembled. ... 

Very few examples of osmium-catalysed ATH reactions of imines have been reported [129]. However, one example is provided by arene iminopyiidine halido complexes which additionally exhibit properties as antitumor agents. Four complexes were prepared and tested, giving reductions in FA/TEA of ca. 22-23 % e.e. in each case (Fig. 42) [130]. 

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