Osmium carbonyl clusters hydrides

Figure 6. The structures of the osmium carbonyl clusters discussed in this work , Os(CO)4 , Os(CO)3 , Os(CO)2 , Os(CO). Hydride and bridging carbonyl ligands are drawn explicitly.

Osmium-Carbonyl-Hydride Clusters and Related Ruthenium Complexes. Our investigation of these species began with a study of the species (/i2-H)(H)Os3(CO)n, prepared from Os3(CO)i2 via the unsaturated species (M2-H)20s3(CO)io (33) (see Reaction 1). 

The hydrogen ligands in osmium carbonyl hydride clusters, whether neutral or... 

Although less fully documented than osmium cluster chemistry, rhenium cluster chemistry has been subjected to many structural studies, including those on approximately 20 neutral or anionic carbonyls, particularly carbonyl hydrides [Rev(CO). H ] of nuclearities x = 2 to 6 (Fig. 7). In addition, some ten or more rhenium carbonyl carbides [Rev(CO)vH C] have been shown to contain a core carbon atom, usually occupying a central octahedral site. These systems offer scope not only to explore for rhenium the trends we have already shown for osmium, but also to study the effect on metal-metal distances (and so enthalpies) of such core carbon atoms, which formally donate all four of their valence shell electrons to the cluster bonding. To our knowledge only one rhenium carbonyl cluster compound, Re2(CO)io, has been subjected to calorimetric study to determine its enthalpy of formation. ... 

Retaining the theme of metal carbonyl clusters, capping considerations in transition-metal clusters have been discussed with reference to [Sb2Co4(CX))] g( A-CX))], and [Bi2Co4(CO)jQ( i-CO)]" 28. An infrared spectroscopic study of the formation of carbonyl rhodium clusters on a rhodium electrode produced by oxidation reduction cycles in acidic solution 2 has also been published. Electrochemistry with ruthenium carbonyls >21 osmium carbonyls 2 jg also reported. Muon spin rotation in a metal-cluster carbonyl compound has been communicated and, lastly, a proton spin-lattice NMR relaxation study of hydride carbonyl clusters has been reported. This provides a method for determining distances involving hydrido ligands... 

Oxidation of metal clusters may also be performed by reaction with Bronsted-acids through straightforward addition of protons to metal backbone. Thus, carbonyl clusters of ruthenium, osmium and iridium are stable in acids and may be pro toned without decomposition. The H-NMR spectra of these carbonyls in concentrated sulfuric or trifluoroacetic acid indicate the formation of cationic metal hydrides ... 

The first mixed-metal cluster of Os-Pd, [Os6Pd(bipy)(CO)i8], was reported in 1994, and since then a variety of mixed-metal cluster that contain various Os Pd ratios have been created. Palladium-pyridine complexes appear to be useful reagents in the synthesis of mixed-metal clusters with osmium carbonyl compounds. " The reaction of the coordinately unsaturated cluster [Os3(yu-H)2(CO)io] with [Pd(NH3)2l2] afforded a number of Os-Pd clusters with a high hydride content. " Both palladium phosphine and bidentate phosphine complexes are useful in the preparation of high-nuclearity mixed-metal clusters. The reaction of [Os3(/i-H)2(CO)io] with [Pd2(/i-dppm)2Cl2] gave 258 and 259, in addition to 260, with the same metal core, " in which the molecule contains a twofold symmetry axis. " " ... 

Binding energy, pentacarbonyliron, 6, 3 Binuclear complexes bis-Cp titanium halides, 4, 522 with Ni-M and Ni-C cr-bonds heterometallic clusters, 8, 115 homometallic clusters, 8, 111 Binuclear dicarbonyl(cyclopentadienyl)hydridoiron complexes, with rand C5 ligands, 6, 178 Binuclear iridium hydrides, characteristics, 7, 410 Binuclear monoindenyl complexes, with Ti(IV), 4, 397 Binuclear nickel(I) carbonyl complexes, characteristics, 8, 13 Binuclear osmium compounds, with hydrocarbon bridges without M-M bonds, 6, 619... 

Heterometal alkoxide precursors, for ceramics, 12, 60-61 Heterometal chalcogenides, synthesis, 12, 62 Heterometal cubanes, as metal-organic precursor, 12, 39 Heterometallic alkenes, with platinum, 8, 639 Heterometallic alkynes, with platinum, models, 8, 650 Heterometallic clusters as heterogeneous catalyst precursors, 12, 767 in homogeneous catalysis, 12, 761 with Ni—M and Ni-C cr-bonded complexes, 8, 115 Heterometallic complexes with arene chromium carbonyls, 5, 259 bridged chromium isonitriles, 5, 274 with cyclopentadienyl hydride niobium moieties, 5, 72 with ruthenium—osmium, overview, 6, 1045—1116 with tungsten carbonyls, 5, 702 Heterometallic dimers, palladium complexes, 8, 210 Heterometallic iron-containing compounds cluster compounds, 6, 331 dinuclear compounds, 6, 319 overview, 6, 319-352... 

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