Pentafluorophenyl compounds

Unlike alkyl-gold bonds the Au—C bonds in pentafluorophenyl compounds are more resistant to cleavage by protic acids, giving more chemical integrity to the complexes. 

Fluorine NMR data for a few representative examples of pentafluorophenyl compounds are given in Table 6.2, along with typical F—F coupling constants.5... 

Pentafluorophenyllithium readily reacted with electrophiles to give the pentafluorophenylated compounds in good yield [195,197,207-211]. The addition-elimination product was obtained instead of the displacement product when pentafluorophenyllithium was reacted with iodotrifluoroethylene [212] (Scheme 72). 

The addition of water and methanol to terminal alkynes has also been studied by Laguna et al. by pentafluorophenyl and mesityl gold derivatives. Both acidic and non-acidic conditions led to high activity, even in the presence of as little as 0.5 mol% of catalyst. The use of pentafluorophenyl compounds allowed them to obtain additional spectroscopic information in the stoichiometric reaction of the complex [Au (C6F5)2C1]2 and phenylacetylene, which showed that gold(III) was the active species in the catalytic process. The reaction followed the Markovnikov rule, as shown in the proposed mechanism (Scheme 8.13), delivering the corresponding ketones or diacetal products [96]. 

The contrast in thermal stability between (C6F5)3B and CF3BF2 is significant for example, the pentafluorophenyl compound was recovered largely unchanged after heating at 270° C for 168 h [82]. Tris(pentafluorophenyl)boron is, in effect, a novel Lewis acid and it is a curious fact that this compound, which was first made over 40 years ago, has... 

Reaction of bis(cyclopentadienyl)diphenyltitanium(iv) with acetylenes affords a general route to titana-indenes. The products from the reactions with phenyl-(trimethylsilyl)ethyne and bis(pentafluorophenyl)ethyne were both characterized by single crystal Z-ray studies, and the structure of the former is shown in (6). The structure is drawn with the one double bond, because, unlike metallocyclo-pentadienes in general, the Ci—Ca bond in (6) is significantly shorter than C3—C4, which is typically aromatic. The two Ti—C bonds in (6) are similar in length but the Ti—Cx bond length in the pentafluorophenyl compound is longer, which the authors attribute to steric factors. ... 

Fild, M. Glemser, O., "Phosphorus, Arsenic, and Antimony Pentafluorophenyl Compounds," Fluorine Chem. Rev. 1969,5,129. 

Several perfluoroalkyl and polyfluoroalkyl, and a number of perfluoro-vinyl and pentafluorophenyl compounds of tin have been prepared (Table II). Their study has added much to our knowledge of the chemical and spectroscopic properties of fluorocarbon-metal compounds. 

Table 6 Spectral parameters for pentafluorophenyl compounds, CgFaX...

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