Heterocyclic ligands, osmium

Heterocyclic astatides, 31 74-77 Heterocyclic ligands, osmium, 37 244 Heterocysts, 38 228-230 Heterodinuclear complexes, quadruply bridged, 40 214-218... 

Fe-Heterocycles and iron complexes with heterocyclic ligands 93 JOM(457)63. Ruthenium and osmium complexes with heterocyclic ligands, clusters including Ru- and Os-heterocyclic fragments 93JOM(457)121. 

Irradiation of an aqueous solution of [Os(NH3)5(N2)] by electrons or y-rays gives [Os(NH3)4(NH2XN2)] by action of OH radicals. Complexes involving heterocyclic ligands [Os(NH3)4(N2)L] (L = pyrazine, JV-methylpyrazium, isonicotinamide, and isonicotinic acid) have been synthesized by displacement of N2 from [Os(NH3)4(N2)2] under Ar. Aerial oxidation of these complexes in the presence of HX (L = pyr or isonicotinic acid) leads to the reversible formation of [Os(NH3)4X(L)]X2 (X = Cl or Br) pK, measurements indicate marked back bonding from osmium to the heterocycle. 

Ruthenium catalysts, coordinated with an N-heterocyclic carbene allowed for the ROMP of low-strain cyclopentene and substituted cyclopentenes (10,23). Suitable ruthenium and osmium carbene compounds may be synthesized using diazo compounds, by neutral electron donor ligand exchange, by cross metathesis, using acetylene, cumulated olefins, and in an one-pot method using diazo compounds and neutral electron donors (24). The route via diazo compounds is shown in Figure 1.7. 

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