title: Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction.
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 of2was 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 of1in hexane, in the presence of 4-substituted tetrafluoropyridines C5NF4X, where X = NMe2, OMe, results in elimination of C2H4and 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 of4shows a planar RhCCNC-five-membered ring. Complexes2-5may also be formed by thermal reaction of CpRh(PMe3)(Ph)H with the respective pyridines at 50 °C.
authors.affiliation: Department of Chemistry, University of York , York, U.K. YO10 5DD.
authors.forename: Barbara
authors.initials: B
authors.lastname: Procacci
authors.affiliation: Department of Chemistry, University of York , York, U.K. YO10 5DD.
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Blagg
authors.affiliation: Department of Chemistry, University of York , York, U.K. YO10 5DD.
authors.forename: Robin N
authors.initials: RN
authors.lastname: Perutz
authors.affiliation: Department of Chemistry, University of York , York, U.K. YO10 5DD.
authors.forename: Nuria
authors.initials: N
authors.lastname: Rendón
authors.affiliation: Department of Chemistry, University of York , York, U.K. YO10 5DD.
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Whitwood