title: Highly fluorinated aryl-substituted tris(indazolyl)borate thallium complexes: diverse regiochemistry at the B-N bond.
abstract: The synthesis and characterization (mainly by (19)F NMR and X-ray diffraction) of highly fluorinated aryl-4,5,6,7-tetrafluoroindazoles and their corresponding thallium hydrotris(indazolyl)borate complexes are reported [aryl = phenyl, pentafluorophenyl, 3,5-dimethylphenyl, 3,5-bis(trifluoromethyl)phenyl]. Thanks to N-H···N hydrogen bonds, the indazoles crystallize as dimers that pack differently depending on the nature of the aryl group. The thallium hydrotris(indazolyl)borate complexes Tl[Fn-Tp(4Bo,3aryl)] resulting from the reaction of aryl-4,5,6,7-tetrafluoroindazoles [aryl = phenyl, 3,5-dimethylphenyl, 3,5-bis(trifluoromethyl)phenyl] with thallium borohydride adopt overall C(3v) symmetry with the indazolyl groups bound to boron via their N-1 nitrogen in a conventional manner. When the perfluorinated pentaphenyl-4,5,6,7-tetrafluoroindazole is reacted with thallium borohydride, a single regioisomer of C(s) symmetry having one indazolyl ring bound to boron via its N-2 nitrogen, TlHB(3-pentafluorophenyl-4,5,6,7-tetrafluoroindazol-1-yl)(2)(3-pentafluorophenyl-4,5,6,7-tetrafluoroindazol-2-yl) Tl[F27-Tp((4Bo,3C6F5)*)], is obtained for the first time. Surprisingly, the perfluorinated dihydrobis(indazolyl)borate complex Tl[F(18)-Bp(3Bo,3C6F5)], an intermediate on the way to the hydrotris(indazolyl)borate complex, has C(s) symmetry with two indazolyl rings bound to boron via N-2. The distortion of the coordination sphere around Tl and the arrangement of the complexes in the crystal are discussed.
authors.affiliation: CNRS, Laboratoire de Chimie de Coordination, 205 route de Narbonne, F-31077 Toulouse, France.
authors.forename: Wilfried-Solo
authors.initials: WS
authors.lastname: Ojo
authors.forename: Kane
authors.initials: K
authors.lastname: Jacob
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Despagnet-Ayoub
authors.forename: Bianca K
authors.initials: BK
authors.lastname: Muñoz
authors.forename: Sergio
authors.initials: S
authors.lastname: Gonell
authors.forename: Laure
authors.initials: L
authors.lastname: Vendier
authors.forename: Viet-Hoang
authors.initials: VH
authors.lastname: Nguyen
authors.forename: Michel
authors.initials: M
authors.lastname: Etienne