Osmium O

Name Formula State Color Solubility AG° (kJ/mole) 

Rh forms all the trihalides (F, Cl, Br, I). The first three have interesting forms, one insoluble and one soluble. When the trihalides are prepared 

Complexes. Rh(III) shows a wide variety of complexes with a coordination number of 6 and with an inert character. These include RhXs (X = F, 

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The platinum-group metals (PGMs), which consist of six elements in Groups 8— 10 (VIII) of the Periodic Table, are often found collectively in nature. They are mthenium, Ru rhodium, Rh and palladium, Pd, atomic numbers 44 to 46, and osmium. Os indium, Ir and platinum, Pt, atomic numbers 76 to 78. Corresponding members of each triad have similar properties, eg, palladium and platinum are both ductile metals and form active catalysts. Rhodium and iridium are both characterized by resistance to oxidation and chemical attack (see Platinum-GROUP metals, compounds). 

A particularly interesting case is that of the platinum metal group which, in addition to platinum (Pt), comprises ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), and palladium (Pd). These carbonyl halides are usually the most practical precursors for metal deposition because of their high volatility at low temperature. Indeed two of them, palladium and platinum, do not form carbonyls but only carbonyl halides. So does gold. 

The platinum-group metals comprise ruthenium (Ru), rhodium (Rh) and palladium (Pd) from the second transition series and osmium (Os), iridium(Ir), and platinum (Pt) from thethird transition series. Little or no C VD investigation of palladium and osmium have been reported and these metalsarenotincludedhere. The properties of the other platinum-group metals are summarized in Table 6.9. 

Iron, Fe ruthenium, Ru osmium, Os cobalt, Co rhodium, Rh iridium, Ir nickel, Ni palladium, Pd platinum, Pt... 

Osmium (Os, [Xe + 4/ l4]5 /66.v2), name from the Greek oop/ij (osme, smell). Powdered Os slowly gives off 0s04 toxic and with a strong smell. Discovered with... 

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