Rhodium Compounds perchlorate

Platinum Compounds Hydrogen hexachloroplatinate(IV)-Copper(II) chloride, 145 Hydrogen hexachloroplatinate(IV)-Diethoxymethylsilane, 76 Platinum-Titanium, 251 Rhodium Compounds [2,2 -Bis(diphenylphosphine)-l,T-binaphthyl](dimethanol)rhodium(I) perchlorate, 36... 

Despite the above similarities, many differences between the members of this triad are also to be noted. Reduction of a trivalent compound, which yields a divalent compound in the case of cobalt, rarely does so for the heavier elements where the metal, univalent compounds, or hydrido complexes are the more usual products. Rhodium forms the quite stable, yellow [Rh(H20)6] " ion when hydrous Rh203 is dissolved in mineral acid, and it occurs in the solid state in salts such as the perchlorate, sulfate and alums. [Ir(H20)6] + is less readily obtained but has been shown to occur in solutions of in cone HCIO4. 

The presence of copper(II) salts, in the optimum ratio Cu Rh=l or 2, considerably increases the rate and the selectivity of the reaction. Rhodium perchlorate alone acts as a catalyst, but cooxidizes the solvent alcohol to a carbonyl compound. With Cu Rh= 1, 85% of the copper precipitates from the reaction mixture as CuCl. 

Strained Carbocyclic Systems.—A large number of examples of catalysis of valence isomerization of strained ring compounds by transition-metal complexes has been considered during the period covered by this Report. The most commonly used metal centres are rhodium and silver, and much of the interest in this field is concentrated on determining and accounting for the differences, in effectiveness and in the nature of the products, between rhodium catalysts and silver catalysts. Thus, for instance, in the presence of [RhCl(nor)]2 or [RhCl(cod)]2, cubane (1) isomerizes to the diolefin (2), but in the presence of silver perchlorate cubane isomerizes to cuneane (3). ... 

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