Pyrene-Based Mono- and Di-N-Heterocyclic Carbene Ligand Complexes of Ruthenium for the Preparation of Mixed Arylated/Alkylated Arylpyridines

By using two pyrene-based mono- and di-N-heterocyclic carbene ligands, two ruthenium complexes (one monometallic and the other dimetallic) have been obtained and fully characterized. The molecular structure of the dimetallic complex has been determined by means of X-ray diffraction studies. The electrochemical studies reveal that the metal–metal communication in the dimetallic complex is weak. The catalytic activity of both complexes has been tested in the arylation of arylpyridines with aryl halides and in the hydroarylation of alkenes, where they showed similar activity. The sequential combination of these two catalytic processes (hydroarylation of alkenes followed by arylation of the resulting alkyl-substituted arylpyridine) allowed the preparation of mixed arylated/alkylated arylpyridines. In this tandem process, the dimetallic complex afforded activity higher than that of the monometallic complex. The activity was compared to that shown by the [RuCl₂(<i>p</i>-cymene)]₂ complex. This reaction constitutes an efficient method for reaching unsymmetrically substituted arylpyridines

Y-Shaped Tris-N-Heterocyclic-Carbene Ligand for the Preparation of Multifunctional Catalysts of Iridium, Rhodium, and Palladium

A series of homo- and hetero-dimetallic complexes of Ir, Rh, and Pd have been obtained using our previously reported Y-shaped tris-NHC ligand. The new complexes can be obtained through the isolation of the corresponding monometallic intermediates (in which the ligand always coordinates in a chelating form) or by a one-pot stepwise synthetic protocol that avoids the isolation of the intermediate. The catalytic properties of the Ir–Pd complexes have been explored in two tandem processes: dehalogenation/transfer hydrogenation of haloacetophenones and Suzuki-coupling/transfer hydrogenation of <i>p</i>-bromoacetophenone. These two complexes have been also tested in two model reactions typically catalyzed by iridium (cyclization of 2-aminophenyl ethyl alcohol to yield indole) and palladium (acylation of bromobenzene with <i>n</i>-hexanal)

Highly Fluorinated Aryl-Substituted Tris(indazolyl)borate Thallium Complexes: Diverse Regiochemistry at the B–N Bond

The synthesis and characterization (mainly by ¹⁹F 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 <i>C</i>_3<i>v</i> 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 <i>C</i>_<i>s</i> 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[F₁₈-Bp^3Bo,3C6F5], an intermediate on the way to the hydrotris­(indazolyl)­borate complex, has <i>C</i>_<i>s</i> 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

Highly Fluorinated Aryl-Substituted Tris(indazolyl)borate Thallium Complexes: Diverse Regiochemistry at the B–N Bond

The synthesis and characterization (mainly by ¹⁹F 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 <i>C</i>_3<i>v</i> 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 <i>C</i>_<i>s</i> 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[F₁₈-Bp^3Bo,3C6F5], an intermediate on the way to the hydrotris­(indazolyl)­borate complex, has <i>C</i>_<i>s</i> 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