Platinum dimer, synthesis

Oxides of Platinum Metals Anodes of platinum (and more rarely of other platinum metals) are used in the laboratory for studies of oxygen and chlorine evolution and in industry for the synthesis of peroxo compounds (such as persulfuric acid, H2S2O8) and organic additive dimerization products (such as sebacic acid see Section 15.6). The selectivity of the catalyst is important for all these reactions. It governs the fraction of the current consumed for chlorine evolution relative to that consumed in oxygen evolution as a possible parallel reaction it also governs the current yields and chemical yields in synthetic electrochemical reactions. 

A versatile synthesis of monoamine platinum(II) complexes of the type ptCl3(amine)], where the nature of the amine ligand can be varied readily, involves treatment of the iodo-bridged dimer [PtI(/r-I)L]2 (L = NH3, methylamine, ethylamine, isopropylamine, cyclobutylamine, and... 

Visser and Ramakers [6] liberated 465 by the action of 2-methylthiirene 1,1-dioxide on the bis(triphenylphosphane)platinum complex 469 (Scheme 6.96) and observed a dimer, probably 474, or several dimers. The synthesis of 469 was accomplished by dehydrobromination of 468b in the presence of bis(triphenylphospha-ne)(ethylene)platinum and was believed to proceed via the trapping of 465 by the platinum complex. Jones et al. [185] doubted this opinion and regarded the reversed sequence as more likely, that is, the complexation of 468b by (PPh3)2Pt followed by the dehydrobromination. 

Nonetheless, a number of electroorganic synthesis reactions are known whose outcome i.e., whose yield and selectivity, is decisively determined by the nature of the electrode so that heterogeneous acceleration of at least one of several competitive reactions of the electrogenerated reactive intermediates might be anticipated. A famous case is the Kolbe reaction, which is essentially the anodic dimerization of alkyl radicals that are generated at platinum anodes by anodic oxidation of the anions of carboxylic acids ... 

Nevertheless, synthesis of the monocyclopropenylidene platinum complex cis-Cl2(Bu3P)Pt[C3(f-Bu)2] was achieved when 3,3-dichloro-l,2-di-f-butylcyclopropene was treated in refluxing benzene with the dimeric complex /i-[(Bu3P)Cl2Pt]2 in a 2 1 ratio, instead of Pt° (equation 275)351. The reaction may involve a dimer intermediate analogous to that obtained in the palladium series above (equation 273). 

Heterometal alkoxide precursors, for ceramics, 12, 60-61 Heterometal chalcogenides, synthesis, 12, 62 Heterometal cubanes, as metal-organic precursor, 12, 39 Heterometallic alkenes, with platinum, 8, 639 Heterometallic alkynes, with platinum, models, 8, 650 Heterometallic clusters as heterogeneous catalyst precursors, 12, 767 in homogeneous catalysis, 12, 761 with Ni—M and Ni-C cr-bonded complexes, 8, 115 Heterometallic complexes with arene chromium carbonyls, 5, 259 bridged chromium isonitriles, 5, 274 with cyclopentadienyl hydride niobium moieties, 5, 72 with ruthenium—osmium, overview, 6, 1045—1116 with tungsten carbonyls, 5, 702 Heterometallic dimers, palladium complexes, 8, 210 Heterometallic iron-containing compounds cluster compounds, 6, 331 dinuclear compounds, 6, 319 overview, 6, 319-352... 

Both amido and pinacol derivatives of B-Si compounds 125 and 126 added to terminal and internal alkynes in the presence of a palladium244-246 or platinum(O) catalyst247 by a mechanism involving an oxidative addition-insertion process (Equation (39)).248 On the other hand, phosphine-free nickel(O) catalyst resulted in the dimerization of alkynes giving a Z,Z-isomer of l-silyl-4-borylbutadiene derivatives.249 Since the palladium-catalyzed cross-coupling at the C-B bond is faster than the G-Si bond of 137, a silylboration-cross-coupling sequence provided a method for the synthesis of 1-alkenylsilanes.246... 

Di-jj-chloro-dichlorobis(ethylene)diplatinum(II) is customarily prepared by evaporating an aqueous solution of H[PtCl3(C2H4)] to dryness and then recrystallizing the dimer.1 However, this procedure has not been applied as a general synthesis of other related olefin complexes. The dimer has also been prepared, but with less success, by the reaction of Na2PtCl6 with boiling ethanol.2 The direct reaction of ethylene with platinum(IV) chloride also provides the dimer,3 but yield data are not available and presumably the method is unsatisfactory. 

Reaction of hydroxylic compounds with butadiene has been studied with palladium compounds. A common feature is the dimerization of butadiene with incorporation of functional groups from alcohols (270). l-Methoxyoctadiene-2,7 was obtained from butadiene and methanol in the presence of Pd(maleic anhydride)(PPh3)2 (273). Complex Pt(PPh3)4 has also been used, although platinum compounds were less effective. Octadienyl esters were obtained from butadiene and acetic acid in the presence of Pd(acac)2 and either PPh3 or P(OPh)3 (294). Palladium complexes were effective for the synthesis of jS,y-unsaturated esters from butadiene, methanol, and CO. The favored mechanism involved addition of a hydropalladium complex to butadiene to give an allylpalladium intermediate (46). 

Another example of this type starts from exo,< xo-tetracyclo[3.3.1.0. 0 ]nonane, which reacted with Zeise s dimer, [(C2H4)PtCl2]2, to form an insoluble platinum complex. This product is solubilized with pyridine and was shown to be a metallacyclobutane complex 4. Synthesis of cxo-tricyclo[3.3.1.0 ]non-6-ene was achieved in 45-55% yield if 4 was treated with dimethyl sulfoxide. ... 

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