Metallocycles osmium

Reactions of ruthenium and osmium cluster carbonyls with heteroatom-substituted and functionalized alkynes (metallocycles) 00IZV1. 

The oxidative addition of C-H bonds of ligands is very common and this reaction forms metal-alkyl or metal-aryl complexes. In osmium triarylphosphine complexes, orthomet-allation gives four-membered metallocycles. When the ortho... 

Other formations of metallocycles are possible with various unsaturated substrates. With Roper s osmium methylene complex, the carbenie earbon reaets with a nucleophihe substrate (CO) as well as with an electrophilie one (SO2) ... 

The dihydroxylation of olefins is catalyzed by OSO4. Sharpless has proposed olefin coordination on osminm followed by formation of a metallocycle analogous to met-allacyclobutanes in metathesis, then generation of a 5-membered ring. Another mechanistic possibility is direct formation of the 5-membered ring metallocycle without prior coordination of the olefin on osmium. 

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