Osmium mixed cluster compounds

The possibility of coordination of a two-electron ligand, in addition to arene, to the ruthenium or osmium atom provides a route to mixed metal or cluster compounds. Cocondensation of arene with ruthenium or osmium vapors has recently allowed access to new types of arene metal complexes and clusters. In addition, arene ruthenium and osmium appear to be useful and specific catalyst precursors, apart from classic hydrogenation, for carbon-hydrogen bond activation and activation of alkynes such compounds may become valuable reagents for organic syntheses. 

A mixed Pt-Rh cluster of corpulent proportions [Pt4Rhjg(CO)35] - has been reported by Fumagalli et aJ . The same groups is responsible for some Re-Ir clusters via addition of tIr(CO)4l" to fRe2(p-H)2(CO)g], and new Mi-Bi clusters . Adams has contributed to the swelling numbers of mixed-metal cluster compounds with RugPt 2 (CO) 23(11 -11)2 and other Ru-Pt clusters . A number of osmium-Group VI metal cluster compounds have also been prepared . 

One of the most important links between alkylidyne and alkyne compounds is that one of the first synthetic routes for cobalt al-kylidynes involved alkynes as reagents (264-268). In later studies, several other synthetic routes to cobalt (269-280), rhodium (281, 282), iron (283-285), molybdenum (286, 287), ruthenium (288-292), osmium (293, 294), nickel (295, 296), and some mixed-metal (165, 297-302) clusters have been developed. Reagents employed include carbynes (166, 277, 280), alkali metals (269), carbon disulfide (275), dithioesters (276, 282), RCC13, and acids (281, 282). 

Metal carbonyl clusters containing four or more metal atoms are made by a variety of methods osmium in particular forms a range of binary compounds and pyrolysis of Os3(CO)i2 yields a mix of products (equation 23.15) which can be separated by chromatography. 

This section is dedicated to a description of the chemistries of trinithenium and triosmium clusters that do not contain hydrocarbon ligands. This section should be viewed as an addition to the chemistry described in sections 32.5 and 33 of COMC (1982) and section 12 of COMC (1995) as most of the main themes have been developed in the previous two decades. Overall, the interest in the cluster chemistry of ruthenium and osmium during the period 1994-2004 has tended to focus mainly on higher nuclearity and mixed metal clusters in order to enhance the developments in catalysis and bridge the gap between molecular clusters and nanoparricles. However, triruthenium and triosmium clusters continue to play a pivotal role in the chemistry of ruthenium and osmium. Both classes of clusters can be, and are, used extensively as precursors for the synthesis of higher nuclearity clusters as well as the formation of mono- and bimetallic complexes. No up-to-date review of the chemistry of either Ru3(CO)i2 or Os3(CO)i2 and their compounds is available, but several annual reviews of the chemistry of mthenium and osmium, which include the chemistry of the trinuclear clusters, are available. ... 

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. " " ... 

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