Rhodium thiocyanates

Nondestructive reactions of trisacetylacetonates of chromium(lll), cobalt(lll), and rhodium(lll) are reviewed. Halogenation, nitration, thiocyanation, acylation, formylation, chloromethylation, and aminomethylation take place at the central carbon of the chelate rings. Trisubstituted chelates were obtained in all cases except acylation and formylation. Unsymmetrically and partially substituted chelates have been prepared. Substitutions on partially resolved acetylacetonates yielded optically active products. NMR spectra of unsymmetrically substituted, diamagnetic chelates were interpreted as evidence for aromatic ring currents. Several groups were displaced from the chelate rings under electrophilic conditions. The synthesis of the chromium(lll) chelate of mal-onaldehyde is outlined. 

This report covers two topics (1) The generation of 2-thioxo-2,4-dihydro-3fT-imidazol-l-ium-l-imides as intermediates in the course of [3+2] cycloaddition reactions of azoalkenes and thiocyanic acid resulting in the formation of l-aminoimidazole-2-thione derivatives some further reactions of these heterocycles are presented as well. (2) The rhodium-catalyzed intramolecular interaction of co-diazenyl a -diazo ketones giving rise to the formation of mostly two cyclic azomethine imine isomers with an exocyclic terminal nitrogen atom and with all three... 

The properties of irans-RhCl(CO)(PPh3)2 (m.p. 195-197°) and /mns-RhCl(CO)(AsPh3)2 (m.p. 242-244°) have been given. The chlorides can be rapidly converted to the corresponding bromides, iodides, or thiocyanates by the interaction in acetone solutions at room temperature with lithium bromide, sodium iodide, or potassium thiocyanate, respectively. Alternatively, rhodium (III) chloride can first be converted to the bromide or iodide by boiling the ethanolic solution with a ca. fivefold excess of lithium bromide or iodide. 

We found that when an aqueous solution of chloropentammino-cobalt(III) dichloride, [(NH3)5ClCo]Cl2, was boiled with two equivalents of the triamine, the cold concentrated solution deposited the orange crystals of bis(triaminopropane)cobaltic trichloride (VII X = Cl), which when treated in aqueous solution with sodium iodide deposited the orange-brown tri-iodide (VII X = I) (29)j and with sodium thiocyanate deposited the pale brown trithiocyanate (VII X = SCN) (28), The almost colorless crystals of bis(triaminopropane)rhodium(III) tri-iodide (VIII X = I) were similarly prepared (1925) (29). 

Thermodynamic parameters governing the outer-sphere equilibria between [Rh(en)3] and SO4" have been obtained. At 3.38, the equilibrium constant for formation of [Rh(NH3)5NCSAg] from Ag and the rhodium-bound thiocyanate complex is less than that between Ag and free NCS". ... 

In Table 8 appear complexes of rhodium with nitrile oxides, as well as some other related complexes with thiocyanates, isocyanates and iso thiocyanates. 

The formation of (II) provides a quite selective spot test for palladium. Gold must be removed prior to the test because it will cause the development of a deep ruby red in the spot plate test and a diffused violet spot on the paper, apparently due to the reduction of the gold ions to the colloidal metal. Interference may also arise from 0s04 , Os+, Ru+, and RuCle ions because they have distinct self-colors. Mercurous ion causes partial interference by the reduction of part of the palladium to the elementary state, but a positive response can still be seen. It is possible to detect I part of palladium in the presence of 200 parts of platinum or 100 parts of rhodium. Less favorable ratios should be avoided because of the color of these salts. No interference is caused by mercuric and iridic chloride, but free ammonia, ammonium ions, stannous, cyanide, thiocyanate, fluoride, oxalate, and tetraborate ions do interfere. Lead, silver, ferrous, ferric, stannic, cobaltous, nickel, cupric, nitrite, sulfate, chloride, and bromide ions do not interfere. 

Retrodiene scission 17, 198 Rhodanides s. Thiocyanates Rhodium-alumina 16, 75/6 ... 

CaH2oCuNgS2, Bis(1,3-diaminopropane)copper(II) thiocyanate, 37B, 617 CaH2oIN60i,Rh, Diamminebis(dimethylglyoximato)rhodium( 111) iodide, 44B, 912... 

Retrodiene scission 19, 766 Rhodanides s. Thiocyanates Rhodium-alumina 19, 67/8... 

Jaya, S. Rao, T. R Ramakrishna, T. V. Spectrophotometric determination of rhodium(III) in thermocouple wires using thiocyanate and Rhodamine 6G. Analyst 1983,108,1151-1155. 

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