The properties of perfluoro-alkyl and -aryl transition metal complexes

The properties of perfluoro-alkyl and aryl transition metal complexes 

A most striking property of M—cr-Rf complexes is their marked thermal stability in comparison with the hydrocarbon analogues. Thus perfluoro- 

Generally, pentafluorophenyl complexes are more stable than perfluoro-alkyl analogues [241]. TUs enhanced stability presumably arises from an increased strength of the M-perfluoroaryl bond by donation of the metal electrons to 7i -orbitals of the aryl ligand. This increased bond strength would increase the kinetic stability of the compound by increasing the energy necessary for dissociation of the M—Rf bond. 

Perfluorohydrocarbon- r-metal complexes are also more stable to reaction with oxygen than thdr hydrocarbon analogues. Other differences between M—Rf and M— R, complexes are the greater resistance of the former to cleavage reactions with acids, and the greater volatility of the fluorocarbon complexes. 

It is interesting that metiil-perfluorocarbon systems do not readily undergo carbonyl insertion reactions, as do hydrocarbon complexes. Only one carbonylation reaction has been report and that occurs only in low yields and under rigorous conditions [244]. The reluctance of the M—Rf system to carbonylate may be associated with the known instability of the RfCO group. 

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