Reports: AC3

44147-AC3 Transition Metal-Templated Reduction of Carbon-Fluorine Bonds: A New General Route to Unsaturated Fluorocarbon Ligands

Russell P. Hughes, Dartmouth College

Initially we discovered that the first transition metal carbene complexes containing two trifluoromethyl substituents could be prepared and isolated; the complex Ir[=C(CF3)2]Cp*(CO) was prepared by reduction of Ir[CF(CF3)2]Cp*(CO)(I) with Na/Pb alloy and characterized crystallographically. Further reduction of the perfluorocarbene ligand with KC8 to give a perfluoroallene complex could be achieved (1). In soon to be published work, the corresponding compound Ir[=C(CF3)(CF2CF3]Cp*(CO) has been prepared and characterized crystallographically (2). It undergoes further reduction to give a more diverse series of products, including the hexafluoro-2-butyne complex Ir(CF3CCCF3)Cp*(CO) and the tetrafluorobutatriene complex Ir(CF2=C=C=CF2)Cp*(CO), the PMe3 analogue of which we have already reported (3). Efforts to extend this methodology to other members of group 9 and to group 10 metals are underway, but the precursor target molecules have proven more difficult to prepare.

Following our initial discovery of methodology to make the first examples of complexes containing CF as a terminal ligand (4), we have now extended this to the synthesis of the full series of group 6 complexes M(Cp#)(CO)2(CF) [Cp# = Cp, Cp*](5). Chemical reactivity and DFT studies of these novel compounds are underway. Efforts to prepare other CF complexes will be guided by the isoelectronic relationship between terminal CF and NO ligands.

A review article on this and related work has been accepted for publication and will appear later this year (6).

(1) Yuan, J.; Hughes, R. P.; Rheingold, A. L., Eur. J. Inorg. Chem. 2007, 4723-4725.

(2) Yuan, J.; Hughes, R. P., unpublished observations.

(3) Hughes, R. P.; Laritchev, R. B.; Zakharov, L. N.; Rheingold, A. L., J. Am. Chem. Soc. 2004, 126, 2308-2309.

(4) Huang, H.; Hughes, R. P.; Landis, C. R.; Rheingold, A. L., J. Am. Chem. Soc. 2006, 128, 7454-7455.

(5) Huang, H.; Hughes, R. P., unpublished observations.

(6) Hughes, R. P., Eur. J. Inorg. Chem. 2009, in the press.