This voLume describes the buLk metaL rhodium and its aLLoys with arsenic to ruthenium in accordance with the GmeLin system. The first section, pages 1 through 37, covers in detaiL the foLlowing properties of the metal: CrystaLlographic properties; seLt-diffusion; me- chanicaL properties (tensiLe properties, eLastic moduli, hardness, etc. ); thermaL properties (thermaL expansion, vapour pressure, specific heat, thermaL conductivity, etc. ); eLectricaL and magnetic properties (eLectric resistivity, superconductivity, HaLL effect, thermoeLectric force, magnetic susceptibiLity, etc. ); eLectrochemicaL behaviour and chemicaL reactions. A number of subject matters on metaLlic rhodium are aLready contained together with those of other pLatinum group metals in appropriate chapters of "PLatinum" SuppL. VoL. A 1, 1986. These incLude 1) preparation and eLectrodeposition, 2) zone-refining operations, and 3) chemicaL vapour deposition, sputtering, and thermaL evaporation. Likewise, "PLatinum" SuppL. VoL. 2, 1989, aL ready contains information on the 1) separa- tion and properties of the Rh isotopes, 2) physicaL properties of the Rh atom and the atomic 2 ions Rh+ and Rh +, 3) the formation of Rh cLusters, and 4) the moLecuLar properties of Rh * 2 The second and major portion of this voLume, pp. 38 to 273, deaLs with the physicaL and chemicaL properties of rhodium aLloys. Phase diagrams of a Large number of binary and muLticomponent systems are treated in detaiL as weLL as the crystaLlographic and other properties of many intermetalLic compounds.

With platinum and rhodium, palladium is one of the most important members of the platinum metal group. The last Gmelin treatment of it was in 1942, and knowledge of its properties and chemistry has made enormous strides since then. This volume is primarily concerned with binary compounds and with the coordination complexes derived from them. Although it is a member of the nickel-palladium-platinum triad, it more closely resernblas platinum in its binary and coordination chemistry, though being a second-row transition element it displays less tendency than does platinum to assume higher oxidation states. ln heterogeneous and homogeneous catalysis, referred to at appropriate points, palladium and its complexes are of great importance in bulk and fine chemieals production, effecting a wide variety of organic transformations. The arrangement of material in this volume follows the traditional Gmelin arrangement. Within each category of compounds or complexes the material is arranged, as usual, in order of ascending metal oxidation states (e. g., palladium(ll) precedes palladium(IV)). The chemistry of the palladium-hydrogen system is so large that it merits a separate volume, so this book starts with the binary oxides and oxopalladates followed by hydroxides, hydroxo complexes and aquo complexes. Then nitrides and nitrates are treated. They are followed by the large chapters on halides and their complexes (172 pages). The largest single chapter in this volume (11 0 pages) deals with chlorides, chloropalladates and other chloro complexes.