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Triosmium Clusters

1986; Elsevier BV; Linguagem: Inglês

10.1016/s0065-3055(08)60003-9

2162-7614

Antony J. Deeming,

Organometallic Complex Synthesis and Catalysis

This chapter discusses triosmium clusters. Dodecacarbonyltriosmium, OS3 (CO) 12, has been one of the key compounds in the development of transition-metal clusters, because it can undergo a wide range of reactions giving many new clusters, more often than not without any change of nuclearity. Triosmium dodecacarbonyl is the best starting material for triosmium clusters, and hundreds of compounds have now been formed by the reaction of inorganic or organic substrates, directly or more commonly with more reactive derivatives, such as OS3H2(CO)10, Os3(CO)11,L (16–18), or Os3(CO)10 L, (18–21) where L is weakly bound. It is useful to classify compounds so that they may be compared and normal behavior distinguished from the abnormal. This situation is found rarely and is only to be expected when strongly bridging ligands maintain the trinuclear cluster intact. Interest in μ3 ligands lies in the variety of molecules that may be used, in the variation of the number of electrons donated by the bridge, and in the potential, the ligands have to rotate with respect to the three metal atoms. OS3 (CO) 12 was first reported by Hieber as Os2(CO)9 in 1943. The reaction of OsO4 with HI gave an oxyiodide, which was treated with Ag powder in benzene at 150°C under CO (200 atm) to give OS3 (CO)12 in poor yield. Ultraviolet photolysis of OS3 (CO)12 in the presence of dienes, such as butadiene, cyclooctatetraene, or cyclooctadienes leads to the mononuclear species of type Os(CO)3(diene).