Abstract
Irradiation of CpRh(PMe3)(C2H4) (1; Cp = η5-C5H5) in the presence of pentafluoropyridine in hexane solution at low temperature yields an isolable η2-C,C-coordinated pentafluoropyridine complex, CpRh(PMe3)(η2-C,C-C5NF4) (2). The molecular structure of 2 was determined by single-crystal X-ray diffraction, showing coordination by C3–C4, unlike previous structures of pentafluoropyridine complexes that show N-coordination. Corresponding experiments with 2,3,5,6-tetrafluoropyridine yield the C–H oxidative addition product CpRh(PMe3)(C5NF4)H (3). In contrast, UV irradiation of 1 in hexane, in the presence of 4-substituted tetrafluoropyridines C5NF4X, where X = NMe2, OMe, results in elimination of C2H4 and HF to form the metallacycles CpRh(PMe3)(κ2-C,C-CH2N(CH3)C5NF3) (4) and CpRh(PMe3)(κ2-C,C-CH2OC5NF3) (5), respectively. The X-ray structure of 4 shows a planar RhCCNC-five-membered ring. Complexes 2–5 may also be formed by thermal reaction of CpRh(PMe3)(Ph)H with the respective pyridines at 50 °C.
Highlights
There has been substantial recent progress in C−F bond activation of aromatic and alkene C−F bonds in both stoichiometric and catalytic reactions.[1]
Albrecht reviewed cyclometalation reactions using d-block transition metals, showing many examples of metallacycles successfully applied in organic transformations, in catalysis and in various other domains of materials science.[2]
The two fluorines close to N (F2, F6) resonate at lower field at δ −55.5 and δ −119.8, F5, which is not involved in the η2 coordination, resonates at δ −155.7, and the two remaining fluorines appear at δ −157.3 (F4) and δ −169.0 (F3) (Scheme 3)
Summary
There has been substantial recent progress in C−F bond activation of aromatic and alkene C−F bonds in both stoichiometric and catalytic reactions.[1] Transition-metal-mediated C−F bond activation holds out the prospect of new ways of making fluorocarbons. It has been found to be an excellent method of generating metal fluoride complexes.1e The analogy to C−H bond activation is tempting, but the contrasts can be revealing. Albrecht reviewed cyclometalation reactions using d-block transition metals, showing many examples of metallacycles successfully applied in organic transformations, in catalysis and in various other domains of materials science.[2] Since many other papers have been published presenting characterizations of new metallacycles,[3] applications in hydrodefluorination catalysis,[4] oxygen sensing,[5] and transfer hydrogenation.[6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
