Osmium reactivity patterns

In our laboratory we have examined the reactivity pattern of [0s3(y-H)2(C0)10], an unsaturated cluster which can be represented as possessing an osmium-osmium double bond in its classical valence bond representation. We find (2,3) that this compound undergoes a number of reactions with metal carbonyls which in some cases can be formulated as proceeding through intermediates analogous to metal olefin complexes ... 

A second type of reactive metal-silicon bond involves multiple bonding, as might exist in a silylene complex, LnM=SiR2. The synthesis of isolable silylene complexes has led to the observation of new silicon-based reactivity patterns redistribution at silicon occurs via bi-molecular reactions of silylene complexes with osmium silylene complexes, reactions have been observed that mimic proposed transformations in the Direct Process. And, very recently, ruthenium silylene complexes have been reported to be catalytically active in hydrosilylation reactions. 

The effect of metal basicity on the mode of reactivity of the metal-carbon bond in carbene complexes toward electrophilic and nucleophilic reagents was emphasized in Section II above. Reactivity studies of alkylidene ligands in d8 and d6 Ru, Os, and Ir complexes reinforce the notion that electrophilic additions to electron-rich compounds and nucleophilic additions to electron-deficient compounds are the expected patterns. Notable exceptions include addition of CO and CNR to the osmium methylene complex 47. These latter reactions can be interpreted in terms of non-innocent participation of the nitrosyl ligand. 

Only recently first reports appeared describing the potential of the nanostructured thin block copolymer films for lithographic etching. A thin film of polystyrene-block-polybutadiene with a hexagonal cylindrical morphology where the poly-(butadiene) cylinders were oriented perpendicular to the substrate was deposited on a silicon wafer and selectively decomposed by treatment with ozone or converted with osmium tetroxide. By a subsequent reactive ion etching process the pattern could be inscribed into the surface of the silicon wafer yielding small holes or islands with a lattice constant of 27 nm and hole/island sizes of 13 nm [305,312]. 

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