The synthesis and characterization (mainly by F-19 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 center dot center dot center dot 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-tetra-fluoroindazol-2-yl) Tl[F27-Tp((4Bo,3C6FS))*], is obtained for the first time. Surprisingly, the perfluorinated dihydrobis(indazolyl)borate complex Tl[F-18-Bp(3Bo,3C6FS)], 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.