Platinum complexes alcohols

Platinum blue formation, 2,265 Platinum complexes, S, 351-500 acetylacetone reactions, 2,380 acetylides reactions, 5,402 alcohols, 5,465 alkene-1,2-dithiolates optica] recording systems, 6,126 alkenes, 5,403 bonding, 5,403... 

The platinum complex of (W fAo-aUylphenyldimethyl arsine, PtBrg (oA)2, has also been treated with bromine and the products reacted with alcohols (8, 10). Two differences in the reaction sequences are, however, observed ... 

Since these substitution reactions follow a two-term rate law, it is clear that solvent effects are very significant. Poorly coordinating solvents are benzene, carbon tetrachloride and sterically hindered alcohols and strongly coordinating solvents are water, lower alcohols, DMF, DMSO, acetonitrile and nitromethane. The first-order rate constants are greater in DMSO than in water. Since the majority of precursor platinum complexes used in synthetic and mechanistic studies are halo complexes, the replacement of halide ligands by solvent and the reversibility of this reaction are important features of platinum halide chemistry. 

Typical platinum complexes that have recently been prepared from alcoholic KOH solutions and platinum isocyanide precursors are trans-Pt C(OMe)NR)(CHNR)(PEt3)2 (R = C6H4Me-p) (440, 451) and... 

Alcohols, hydrocarbons, and their halide-containing derivatives, and their mixtures, are the most frequently used solvents (Solv). The majority of these reactions take place at room temperature or with slight heating, necessary for dissolution of the reagents. The transformation (3.199) was one of the first template reactions of the examined type [434]. In this reaction, the coordinatively unsaturated platinum complex is an N-base and silver nitrate is a Lewis acid ... 

All the compounds are crystalline solids, and with the exception of RuH(OCOCH3)(CO)[P(C6H5)3]2, can be manipulated in air briefly without decomposition. The platinum complex, ris[Pt(OCOCH3 )2 P(C 6H 5 )3 2] is soluble in chloroform, dichloromethane, and methanol but practically insoluble in benzene and acetone. The other complexes are soluble in chloroform and dichloromethane, moderately soluble in benzene and acetone, and almost insoluble in light alcohols. Analytical and spectroscopic data are given in the following table. Infrared data refer to mulls in Nujol XH nmr data were obtained at 90 MHz using solutions in chloroform-d and are referenced to TMS. 

Scheme 4 shows a platinum catalyst 1 containing such a bis-SPO bidentate ligand anion, designed for the hydroformylation of ethylene and of 1-heptene, and various other, similarly built, platinum catalysts. Catalyst 1 has an activity comparable to that of the commercial cobalt catalysts that were used at the time and displays a higher selectivity for linear products than the cobalt-containing catalysts (66). Like the latter, the platinum complex exhibits hydrogenation activity to give, in part, alcohols in addition to aldehydes and also produces alkanes (an undesired reaction that implies a loss of feedstock). The catalysts are also active for isomerization, as are the cobalt complexes, and for internal heptene hydroformylation (Table 1), with formation of 60% linear products. 

Alkoxycarbonyl-platinum complexes form in reactions between a cationic metal-carbonyl complex and an alcohol ... 

The polysiloxane network is formed during part fabrication. In injection molding, the acetylenic alcohol, which acts as a fugitive inhibitor of the vinyl-addition reaction, is volatilized at low temperature as the pellets enter the feed throat. The platinum complex is activated at the process temperature of the urethane (170-185 °C). The vinyl-addition reaction is initiated by the melt state, and the parts generated demonstrate mechanical properties consistent with the formation of a silicone IPN. The fabricated parts are translucent. The physical properties of this formulation (PTUE 205) are given in Table 1. 

Most research and industrial syntheses are carried out in the presence of platinum complexes, with H2PtCl6 commonly used as the initial precursor. A solution of this catalyst in isopropanol (1-10%) is referred to as Speier s catalyst [11]. In addition to isopropanol other solvents (alcohols, ketones, aldehydes, ethers, esters, THF, hydrocarbons) have also been used in the preparation of active catalysts from chloroplatinic acid. Since 1957 hundreds of catalysts based on chloroplatinic acid and other d -Pt and d °-Pt° complexes have been reported [1-5]. The Karstedt s type of catalyst obtained by treating hexachloroplatinic acid with divi-nyldisiloxane was discovered in 1973 [33] and has predominated in recent years. This catalyst has the empirical formula Pt2(CH2=CHMe2SiOSiMe2CH=CH2)3. Its structure was reported [34, 35]. 

Of the new Pt catalysts reported since 1990 platinum complexes with new ligands and activators are noteworthy. Cyclodextrin complexes of platinum (as host-guest complexes) have been employed as hydrosilylation catalysts active at elevated temperature after releasing the guest compound [40]. Some other organic compounds have recently been used as activators (ligands) of Pt complexes, e. g., unsaturated secondary and tertiary alcohols and silylated unsaturated alcohols [41], alkadiynes, cyclooctadiene [42], and vinylnorbomene as well as quinones and methylnaphthoquinones [43]. 

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