Perfluoroalkyl derivatives transition metals

The development of new types of reagents for the formation of perfluoroalkyl derivatives of metals is of interest since, as discussed below (Section II), the types of trifluoromethyl complexes which could be prepared until quite recently have been severely limited by the synthetic methods that have been historically available. Virtually all of the trifluoromethyl-containing transition metal species prepared prior to the 1980s arose from only two types of reactions thermal decarbonylations of trifluoroacetyl complexes or oxidative additions of CF3I. 

The first successful syntheses utilizing trifluoromethyl iodide in transition metal chemistry were reported by Stone and his students. Stone reasoned that if CF3I would not react with transition metal anions to form trifluoromethyl derivatives [see Eq. (3)] then perhaps compounds containing perfluoroalkyl substituents could be generated by the oxidative addition of perfluoroalkyl halides to low valent transition metal substrates (9,10). The first reported trifluoromethyl-substi-tuted transition metal complex prepared by this route is shown in Eq. (4) (41). 

The carbon-iodine bond in perfluoroalkyl iodides is usually susceptible to homolytic fission this was exploited in early work on the synthesis of mercurials and in later work relating to group IVB and transition-metal derivatives (Figure 10.2). 

H. C. Clark Advan. Fluorine Perfluoroalkyl derivatives of the 44 Transition metal compounds, p. 54... 

Few electrochemical studies have been carried out on perfluoroalkyl derivatives of transition metals, but polarographic and cyclic voltammetric measurements have been reported for a series of Co(salen)R complexes in which R was CF3 and CH3, among others (61). These studies indicated that in THF the reduction of Co(-salen)CF3 to Co(salen)CFj is 0.574 V easier (less negative) than the corresponding reduction of the methyl... 

The organometallic compounds prepared from alkali metal derivatives of metal carbonyls include compounds in which a transition metal of a metal carbonyl residue is cr-bonded to another atom such as a carbon atom in an alkyl, acyl, aryl, or perfluoroalkyl group, to the heavier congeners of carbon —silicon, germanium, tin, and lead—to mercury and gold which form unusually stable compounds, and even to other transition metals. The preparation and properties of all of these classes of compounds will be considered and, for the sake of completeness, a few related compounds prepared by routes other than those involving anionic metal carbonyl derivatives will be discussed. 

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