Aliphatic Carbon−Fluorine Bond Activation Using (C5Me5)2ZrH2

Abstract

Carbon-fluorine bonds are among the strongest and most inert single bonds found in organic compounds.1 The extraordinary properties of fluorocarbons have led to their increased use commercially and, in turn, to an increased interest in the study of C-F activation. In particular, the development of CFC disposal methods remains a challenging task.2 A variety of early transition metal complexes have been shown to be reactive toward aromatic C-F bonds such as those in perfluorobenzene,2-4 while only a few metal complexes show well characterized reactions with aliphatic fluorocarbons.5 The use of early transition metal hydride reagents in C-F activation remains largely unexplored. In fact, only two examples of C-F activation by early transition metal hydrides have been documented.6 The dihydride complex Cp*2ZrH2 is known to react with a variety of unsaturated small molecules through what are commonly classified as electrophilic concerted addition reactions.7 We have found that Cp*2ZrH2 reacts with many types of fluorinated substrates to give hydrogenated organic products and Cp*2ZrHF. Reaction of Cp*2ZrH2 (1) with 1-fluorohexane in cyclohexaned12 at ambient temperature under 1.3 atm H2 has been found to produce hexane and Cp*2ZrHF (2) in quantitative yield (eq 1).