Triphenylcyclopropenyl cation

The chemistry of cyclopropenyl ions is dominated by reactions which lead to cyclopropenes, usually either by reduction or by their reactions with nucleophiles. For example, triphenylcyclopropenyl cations, as well as some other derivatives, can be reduced in good yield to the corresponding cyclopropene using lithium aluminum hydride (equation 11)27,28 however, diphenylcyclopropene which is produced in the analogous reduction of... 

Reduction of triphenylcyclopropenyl salts with other reagents including Mg and Zn have been reported. Reduction of triphenylcyclopropenyl cations by these metals yields 22 (equation 14), whereas the diphenyl species yield tetraphenylbenzene (equation 12) . Isolation of bis-cyclopropenes has also been reported from reductions using chromium(II)... 

Extensive studies have been carried out on the electrochemical reduction of the triphenylcyclopropenyl cations " . These reactions are presumed to proceed via the route outlined in equation 15. Although the bis-cyclopropene 22 is the major product,... 

The cyclopropene produced upon reaction of the triphenylcyclopropenyl cation with aqueous alkali collapses to give the ring-opened product 26 (equation 21). D yakonov and coworkers have used this reaction to confirm the symmetry of the cation by labeling... 

Reaction of Na[Co(CO)4] with the triphenylcyclopropenyl cation in acetonitrile gives 7r-triphenylcyclopropenylcarbonylcobalt tricarbonyl (L) as air-stable yellow crystals, m.p. 134-135.5° C 207). 

The cyclopropenyl ether (10 R = Et), with FeCla, in refluxing ethanol, gives triphenylcyclopropene and indenone (11). The former results from reduction of the triphenylcyclopropenyl cation by ethanol the latter is thought to involve oxidation of the hydroxy-cyclopropene (10 R = H) to the radical (12) (or further to the cation), which cyclises."... 

Analogously, the reaction of rhenate pentacarbonyl anion [Re(CO)5] as its sodium salt, with cyclopropenylium cations [C3Ph3]X (X = BF4, PF6) in THF, at -80 °C, afforded the octahedral n-coordinated pentacarbonyl ( /-l,2,3-triphenylcyclopropenyl)rhenium complex in 60-73% yield (equation 195)26 269. The l3C NMR (acetone-, .) spectrum dis-... 

A comparison of the reduction potentials of triphenylcyclopropenyl (40, Ar = Ph) and triphenylmethyl (42) cations indicates that the former is harder to reduce ... 

Shono and coworkers studied the electrochemical formation of triphenylcyclopropenyl radical and its chemical behavior in the presence of hydrogen donors and olefins (Table 10). Wasielevsky and Breslow studied the reduction of various cyclopropenyl cations by second harmonic AC voltammetry (Table 11). They detected adsorption effects for some of the cations at the Pt but not at the Au electrode. The electrochemical data were used in thermodynamic sequences to evaluate the basicity of various cycloproenyl anions as well as the C-O bond dissociation energy of cyclopropenols. 

DDQ has proved useful also for the preparation of salts containing stable aromatic cations, for example tropylium and triphenylcyclopropenyl perchlorate. ... 

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