Platinum methyl

This reaction can even be carried out in strongly acidic solution, since the iodomethyl complex is stable in such conditions. No evidence is found for protolysis of the platinum-methyl bond. For higher-homolog alkyl groups, the stability of the iodoalkyl complex is lower, and the reaction of Pt2(pop)/ with higher alkyl iodides may give the diiodo diplatinum(III) complex rather than the iodoalkyl complex (Eq. 13). These reactions... 

Prior to 1982, Crabtree s report of the reaction of cyclopentane with a solvated IrH2(PPh3)2+ species to give a cyclopentadienyl-iridium product stood as the only well characterized example of a reaction of an alkane with a homogeneous transition metal, in contrast to the widespread reactivity of arenes [2]. Based upon the instability of the platinum methyl hydride complex Pt(PPh3)2(CH3)H, it was believed that alkane oxidative addition might not be a thermodynamically feasible process, and consequently few attempts were made to attempt such a reaction [3]. It was not until the discovery of the formation of stable alkane oxidative addition products in 1982 that it was realized that reactions of hydrocarbons were in fact feasible. 

L. Mond and his co-workers discovered it in 1888. The platinum methyls, prepared in 1907 by W. J. Pope, were amongst the first-known transition metal alkyls, and the discovery by W. Reppe in 1940 that Ni complexes catalyse the cyclic oligomerization of acetylenes produced a surge of interest which was reinforced by the discovery in I960 of the jr-allylic complexes of which those of Pd arc by far the most numerous. 

The use of complexes as stationary phases is well developed in gas chromatography. For example, Cartoni et al. [87] studied the properties of nickel, palladium, platinum and copper N-dodecylsalicylaldimines (MSal2) and those of nickel, palladium and platinum methyl-N-octylglyoximes (MGly2). It was shown that the stationary phases studied showed specific retention of amines, alcohols and olefinic compounds. Table 6.3... 

R or L Solvent Platinum Methyl 1 Jpt-cI Arsine Methyls 1 Jpt-Ac-C 1 Aromatic Carbons P/pt-/l3-C-C [ Other... 

R or L Solvent Platinum Methyl 1 Jptc [ Arsine Methyls 1 JptAsC 1 Aromatic Carbons Other 1 JptAtCC 1... 

The mechanism of the final step of C-0 bond formation by a formal reductive elimination was included as part of Chapter 11. In particular, two model systems have provided information on the mechanism of this reaction. First, the reaction orders, solvent effects, and electronic effects on the reductive elimination of methyl acetate and methyl aryl ethers from methylplatinum(lV) acetate and phenoxide complexes (Equation 18.16 and Scheme 18.4) indicated that these reductive eliminations occur by backside attack on a platinum methyl. Second, a study of the stereochemistry of the attack of water on a Pt(lV) alkyl showed that the formation of alcohol occurred with the inversion of configuration that reflects a backside attack. ... 

An example involving a larger hydrocarbon molecule is provided by the dehydrogenation (aromatization) of methyl cyclohexane (C6H11CH3) to toluene (C6H5CH3) catalyzed by platinum. Methyl cyclohexane will be abbreviated as MCH. According to Sinfelt (1981), the mechanism can be written as a sequence of reactions in the forward direction only... 

Scheme 4.11 Mechanism of the cyclometallation of the bis-NHC platinum methyl complex 31. Relative free energies given in kcal moF. ...

---