OSMIUM LIGAND DEFICIENT CLUSTERS AS CATALYSTS FOR LIQUID-PHASE HYDROCARBON TRANSFORMATIONS

Reduction of OsO4 by molecular hydrogen in alkane (cycloalkane) or ben zene media at 20-150-degrees-C yields small osmium clusters of the Os1 C0.34-0.48H-0-0.6 composition with a specific surface area of 34-46 m2 /g. The systems obtained are shown to be ligand deficient osmium clust ers (LDC) of 7-16 angstrom in diameter, stabilized by a small amount o f carbonaceous ligands with Os-Os = 2.68-1.70 angstrom and Os-C = 2.11 -2.19 angstrom. The characteristics of these chemically prepared Os-LD C are similar to those of Ni- and Co-LDC, prepared by a vapour phase s ynthesis. The novel Os-LDC effectively catalyze hydrogenolysis of alka nes and cycloalkanes at 100-150-degrees-C and initial H-2 pressure of 5 MPa, hydrogenation of cyclopentadiene and arenes at 20-degrees-C, mu ltiple H/D exchange between CH4 and D2 at 100-120-degrees-C and methan ation of CO2 at 150-180-degrees-C.