Platinum alkyl halides

In 1974, Hegedus and coworkers reported the pa]ladium(II)-promoted addition of secondary amines to a-olefins by analogy to the Wacker oxidation of terminal olefins and the platinum(II) promoted variant described earlier. This transformation provided an early example of (formally) alkene hydroamination and a remarkably direct route to tertiary amines without the usual problems associated with the use of alkyl halide electrophiles. 

Hardacre et al. have developed a procedure for the synthesis of deuterated imidazoles and imidazolium salts [65]. The procedure involves the platinum- or palladium-catalyzed deuterium exchange of 1-methyl-d -imidazole with D2O to give 1-methylimidazole-d , followed by treatment with a deuterated alkyl halide. 

Sn2 attack of the electron-rich platinum(O) on the alkyl halide to give the Ptn(R)X species directly, possibly via an ionic intermediate. 

The most important of the tertiary phosphine complexes of platinum(IV) are Pt(QR3)2X4, generally prepared by halogen oxidation [174] of cis- or trans-Pt(QR3)2X2 (Q = P, As, R = alkyl Q = Sb, R = Me), since direct reaction of the platinum(IV) halides with the ligands leads to reduction. Once made, the platinum(IV) compounds are stable to reduction ... 

An interesting example is the electrolysis of alkyl halides on tin anodes and platinum cathodes which yields dialkyltin dihalides. The current yield is extremely high, Ca 5 g... 

The electrolysis of alkyl halides on platinum cathode and tin anode has been mentioned above. A completely different mechanism is associated with alkylation on tin cathodes. Electroreduction of allyl bromide on tin electrodes yields tetraallylstannane (Ca 90%). This is done in acetonitrile solutions with LiClC>4, Et4NBr or BujNBr as electrolyte and followed by CV with Ag/AgBr reference. Yields decrease to 78% in DMF. The proposed mechanism67 in this case is ... 

Synthetic organic chemistry applications employing alkane C-H functionalizations are now well established. For example, alkanes can be oxidized to alkyl halides and alcohols by the Shilov system employing electrophilic platinum salts. Much of the Pt(ll)/Pt(rv) alkane activation chemistry discussed earlier has been based on Shilov chemistry. The mechanism has been investigated and is thought to involve the formation of a platinum(ll) alkyl complex, possibly via a (T-complex. The Pt(ll) complex is oxidized to Pt(iv) by electron transfer, and nucleophilic attack on the Pt(iv) intermediate yields the alkyl chloride or alcohol as well as regenerates the Pt(n) catalyst. This process is catalytic in Pt(ll), although a stoichiometric Pt(rv) oxidant is often required (Scheme 6).27,27l 2711... 

The generality of the carbon monoxide insertion reaction is clear from reports that methylcyclopentadienyliron dicarbonyl (16), ethylcyclopentadienylmolylbde-num tricarbonyl (66), alkylrhenium pentacarbonyls (50), alkylrhodium dihalo carbonyl bisphosphines (34), allylnickel dicarbonyl halides (35), and mono-and di-alkyl derivatives of the nickel, palladium, and platinum bisphosphine halides (P), also undergo the reaction. The reaction of Grignard reagents (24), and of boron alkyls (51) with carbon monoxide probably takes place by the same mechanism. 

Hydrosilylations of fluorine-containing alkenes are free radical reactions initiated by UV light or organic peroxides The direction of addition is the same as with fluonnated alkyl halides However, the reaction between hydrosilanes and fluorine-containing olefins catalyzed by platinum group metal complexes may result in bidirectional addition and/or formation of a vinylic silane, the latter by de hydrogenative silylation[/] The natures of both the silane and the catalyst affect the outcome of the reaction[7] A random selection of some typical new reactions of silanes are shown in Table 1 [1, 2, 3 4]... 

To utilize the strong reducing power of the 3(da po) excited states of the platinum and iridium dimers, the nonproductive back electron transfer reactions need to be inhibited. An effective way to accomplish this is to use acceptors that are thermally unstable after the initial electron transfer. Reduction of alkyl halides has been shown to lead to short-lived radical anions RXT, which rapidly decompose to give R- and X (k... 

Alkyl halides react under most carbonylation conditions to give significant amounts of elimination products. However, under mild conditions, primary alkyl iodides may be carbonylated with a carbon monoxide-hydrogen mixture, in good yields in the presence of potassium carbonate using platinum catalysts837,838. 

Tetralelluride anions were generated by cathodic reduction of tellurium at — 1.4 V in a cell consisting of a tellurium cathode and a platinum-net anode. AIM solution of dry sodium perchlorate in dimethylformamide served as the catholy te. The tetratelluride ions were then reacted with alkyl halides to yield the corresponding dialkyl ditellurium5. 

Simonet, J. and Peters, D.G. (2004) Electrochemical conversion of primary alkyl halides to alkenes at platinum cathodes. J. Electrochem. Soc. 151, D7-D12. 

Vanhoye and coworkers [402] synthesized aldehydes by using the electrogenerated radical anion of iron pentacarbonyl to reduce iodoethane and benzyl bromide in the presence of carbon monoxide. Esters can be prepared catalytically from alkyl halides and alcohols in the presence of iron pentacarbonyl [403]. Yoshida and coworkers reduced mixtures of organic halides and iron pentacarbonyl and then introduced an electrophile to obtain carbonyl compounds [404] and converted alkyl halides into aldehydes by using iron pentacarbonyl as a catalyst [405,406]. Finally, a review by Torii [407] provides references to additional papers that deal with catalytic processes involving complexes of nickel, cobalt, iron, palladium, rhodium, platinum, chromium, molybdenum, tungsten, manganese, rhenium, tin, lead, zinc, mercury, and titanium. 

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