2- pyridine reaction with platinum complexes

According to reaction (559) these reactions can occur by an oxidation reaction of platinum(II). With one-electron oxidants, the intermediate formation of platinum(III) complexes occurs. The best early example of this type of reaction is in the oxidation of PtCi - and Pt(en)2+ by IrIVCl - in the presence of free chloride ion. The presence of platinum(III) intermediates has been inferred from the rate law.2036 For the oxidation of platinum(II) by gold(III) the kinetic data are consistent with a mechanism requiring a complementary two-electron transfer,2037 with a rate independent of chloride ion. For the substituted pyridine derivatives PtCkLj (L = substituted pyridine) however, the third-order rate law is found with first-order dependencies on PtCl I, Aum and Cl-.2038 Comparisons have been made with the amine complexes PtC L (L = NH2R).2039... 

The addition of methyldichlorosilane to styrene has been carried out homogeneously in the presence of [PtCl2(CgH8)]2 246). This reaction is first-order with respect to the styrene and the silane, and first-order with respect to the platinum complex. In aromatic solvents, an induction period was observed which was attributed to coordination of the aromatic or a second molecule of styrene to the platinum. This necessity of a vacant site was further emphasized by the finding that addition did not occur in donor solvents such as tetrahydrofuran, ether, or pyridine. 

Conversion of norbornadiene to nortricyclenes can also be achieved with organomercurials. This reaction proceeds via transmetalation to form a c-bonded organopalladium system which inserts norbornadiene. Thus an enrfo-cw-addition is observed. Conversions of this type were observed in the phenylation of dichloro(t -norbornadiene)palladium either with diphenyl-mercury or, more conveniently, with sodium tetraphenylborate to give di-/r-chlorobis(2 5,6-t -c ffo-3-phenylbicyclo[2.2.1]hept-e /o-2-yl)palladium (30) via cis addition.By contrast, the analogous platinum complex did not give a phenylation product. The palladium complex 30 underwent reversible ring closure to a nortricyclenyl complex 31 with pyridine. ... 

The compound is a dark red-purple dichroic cystalline material. In time, the crystals develop a thin coating of sulfur. The rhodium(III) complex, which appears to be structurally similar to the platinum(IV) compound, shows much greater reactivity in that sulfur is readily lost on dissolving in water, dimethyl-formamide, or pyridine. From water, a product may be precipitated which appears to contain the [RhSi0] anion. Reaction with cyanide ultimately produces the thiocyanato complex. 

On the other hand, the palladium and platinum complexes of pyridine-2-aldoxime, when treated with acetyl chloride in hot chloroform, gave stable chelates containing the acylated ligand. A monoacetylated palladium chelate was isolated in which 1 mole of pyridine-2-aldoxime was replaced by two chloride ions (see reaction XXIV). This compound was identified by its infrared spectrum, which had a strong carbonyl absorption band near 1790 cm-1. The platinum complex of pyridine-2-aldoxime gave a... 

The reaction between the PtCh ion and alkanes can be induced by irradiation [26]. When a solution of hexachloroplatinic acid and n-hexane in acetic acid is irradiated by light (A > 300 nm) [26a,c,d] or y-quanta [26b], a 7t-coinplex of hex-1-ene with platinum(II) is formed in addition to isomeric chlorohexanes. This complex has been isolated in the form of the pyridine adduct, (hex-l-cne)PtCl2Py. The yield of the it-complex in the y-induced reaction reaches 17% based on Pt. The photochemical reaction is of first order with respect to hexane. It is interesting that the photochemical reaction with hex-2-ene affords the n-complex ofhex-l-ene (Scheme VII.5). This complex can be also prepared by the reaction ofhex-l-ene with PtCL, " under irradiation. It should be noted that the photoinduced reaction of PtCl6 or PtCU with olefins is a convenient method for the synthesis of various n-o efin complexes of platinum(II) [27]. The photostimulated reaction of PtCU with stilbene does not occur, possibly due to steric restrictions. 

A platinum complex with a bipyridine as the most widely used ligand is easily prepared in high yields by reaction with Pt(Me)2(DMSO)2 in toluene to give an air- and moisture-stable product. The ligand exchange reactions proceed easily with other ligands such as phosphine, CO, and pyridine derivative, as shown in Eq. (7.8) [48]. 

Bis(trifluoromethyl)platinum complexes may conveniently be prepared by the reaction of dimethyl(cyclo-octa-l,5-diene)platinum with trifluoro-iodomethane in methylene chloride, followed by displacement of the cydo-octadiene with the required ligand L (L = AsMcs, PMeaPh, pyridine, RNC, etc.) Oxidative addition of iodine thence gives the platinum(iv) compounds ... 

Formation.—Amongst substitution reactions of platinum(u) complexes the reaction of /ra j-[Pt(PEt8)2(R)Cl] (R = o-tolyl) with pyridine in methanol solution is anomalous. In dealing with this reaction in Volume 3 we reported on the nature of the anomaly and its explanation in terms of the mechanism... 

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