Platinum tin complexes

The problem of establishing the solution structure of platinum-tin complexes is complicated by the lability of this system. We have found (16, 17) (and will refer to this later) that these complexes are often dynamic on the NMR time scale. Despite these difficulties it is possible to characterize such molecules using NMR methods. 

From Table II we note that the Pt-195 NMR chemical shifts of the platinum-tin complexes fall in and even at higher field than the classical Pt(0) complexes (e.g. [Pt(CF3-C C-CF3)(PEt3)2] = -4712 ppm, [Pt(frans-stilbene)(PEt3)2] = -5122 (47)). Accordingly it is tempting to seek a relationship between the Pt-195 NMR coordination chemical shift A8 = 8(complex with tin)-8(related complex without tin) and the electron density at the metal. However, the few ESCA data for the chosen test compounds do not indicate a simple charge dependence of the NMR shielding. 

Frankel, E. N., Emken, E. A., Itatani, H., Bailar, J. C., Jr., Homogeneous Hydrogenation of Methyl Linolenate Catalyzed by Platinum-Tin Complexes, presented before the American Oil Chemists Society, Los Angeles, Calif., April 24-27, 1966. 

Olefin isomerization has been widely studied, mainly because it is a convenient tool for unravelling basic mechanisms involved in the interaction of olefins with metal atoms (10). The reaction is catalyzed by cobalt hydrocarbonyl, iron pentacarbonyl, rhodium chloride, palladium chloride, the platinum-tin complex, and by several phosphine complexes a review of this field has recently been published (12). Two types of mechanism have been visualized for this reaction. The first involves the preformation of a metal-hydrogen bond into which the olefin (probably already coordinated) inserts itself with the formation of a (j-bonded alkyl radical. On abstraction of a hydrogen atom from a diflFerent carbon atom, an isomerized olefin results. 

Among the complexes which may function in this way are pentacyano-cobaltate ion, iron pentacarbonyl, the platinum-tin complex, and iridium and rhodium carbonyl phosphines. It has been suggested that with tristriphenylphosphine Rh(I) chloride, a dihydride is formed and that concerted addition of the two hydrogen atoms to the coordinated olefin occurs (16). There are few examples of the homogeneous reduction of other functional groups besides C=C, C=C, and C=C—C=C penta-cyanocobaltate incidentally is specific in reducing diolefins to monoolefins. 

Homs and co-workers described the linkage of ethene and C02 on a supported platinum/tin complex yielding 3-hydroxypropionic acid [73], Another approach to utilizing C02 was pursued by Tominaga and Sasaki, namely hydroformylation with C02 [74]. 1-Hexene, for instance, reads with a mixture of C02 and H2 in the presence of ruthenium dusters giving heptanals, heptanols, and, in small amounts, the undesired hexane as a result of simple hydrogenation. Mechanistically it is assumed that a retro water gas shift reaction occurs, in which CO and H20 are formed from C02 and H2. This carbon monoxide undergoes ordinary hydroformylation with the alkene and H2. 

Figure 11. The model of structure of the platinum-tin complex anion. The inter-atomic distances (and some related bond angles) specified those determined with certainty on the basis of simulation of the RDF in Fig. 10, because of the sufficiently high contribution of these distances to the RDF.

R. TarozaitS, L. Tamasauskaite TamaSiunaite, V. Jasulaitien4, Platinum-tin complexes as catalysts for the anodic oxidation of borohydride, J. Solid State Electrochem. 13 (2009) 721-731. 

Hetorogenized Catalysts.—Reaction of [Ru(NH3)60H] + with a Faujasite-type zeolite gives a supported Ru complex, which effects hydroformylation of ethylene the catalytic species may be ruthenium clusters that are trapped in the zeolite cages. The effect of reaction conditions upon the selectivity of the hydroformylation of methyl methacrylate with [RhH(CO)(PPh3)3] or its polymer-anchored analogue has been investigated and hydroformylation of hex-l-ene and cyclo-octa-1,5-diene has been carried out with cobalt, rhodium, and platinum-tin complexes anchored to an ion-exchange resin via quaternary amino-phosphines. ... 

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