TY - JOUR
T1 - Synthesis of a 14-electron iridium(III) complex with a xanthene-based bis(silyl) chelate ligand (xantsil)
T2 - A distorted seesaw-shaped fourcoordinate geometry and reactions leading to 16-electron complexes
AU - Komuro, Takashi
AU - Furuyama, Keisuke
AU - Kitano, Takeo
AU - Tobita, Hiromi
N1 - Funding Information:
This work was supported by Grants-in-Aid for Scientific Research (Grant Numbers 25410058 , 22350024 , and 23750053 ) from the Japan Society for the Promotion of Science (JSPS) and also partly supported by “Nanotechnology Platform” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan , at the Center for Integrated Nanotechnology Support, Tohoku University. We are grateful to Mr. Shinichiro Yoshida (Tohoku University) for his help with the 2D EXSY measurements of 1a + 1b and 2 and with the solid-state NMR spectroscopic measurements of 1a + 1b . We also acknowledge the Research and Analytical Center for Giant Molecules, Tohoku University, for spectroscopic measurements and elemental analyses. This work was also performed under the Cooperative Research Program of “Network Joint Research Center for Materials and Devices”. We acknowledge Prof. Hideo Nagashima (Kyusyu University) for his warm support in this program. We are also grateful to Ms. Keiko Ideta for her help with the low-temperature NMR spectroscopic measurements of 2 and with the determination of spin-lattice relaxation times (T 1 ) of 2 in the Evaluation Center of Materials Properties and Function, Institute for Material Chemistry and Engineering, Kyusyu University.
PY - 2014/2/1
Y1 - 2014/2/1
N2 - Synthesis, structure determination, and reactions of a 14-electron four-coordinate iridium(III) complex bearing a xanthene-based bis(silyl) chelate ligand, i.e., Ir{κ2(Si,Si)-xantsil}(PCy3)Cl (1a, xantsil = (9,9-dimethylxanthene-4,5-diyl)bis(dimethylsilyl)), are reported. A precursor of 1a, the 16-electron (dihydrido)iridium(V) complex Ir{κ2 (Si,Si)-xantsil}(H)2(PCy3)Cl (2), was prepared by the reaction of [IrCl-(coe)2]2 (coe = cyclooctene) with 4,5-bis(dimethylsilyl)-9,9-dimethylxanthene (xantsilH2) and PCy 3. Dehydrogenation reaction of 2 with 3,3-dimethylbut-1-ene, a hydrogen acceptor, afforded a mixture of 1a and its isomer 1b, abbreviated as 1a + 1b, together with 2,2-dimethylbutane. Single crystals obtained from a CH 2Cl2 solution of 1a + 1b contained only isomer 1a. X-ray crystal structure analysis of one of the crystals revealed that 1a adopts a distorted seesaw-shaped four-coordinate geometry where the coordinatively unsaturated metal center is stabilized by weak agostic interaction of two γ-C-H bonds of the PCy3 ligand. On the other hand, NMR spectroscopic analysis of 1a + 1b demonstrated that 1a is in fast equilibrium with a minor amount of 1b in solution. Replacement of the chloro ligand in complexes 1a + 1b by a triflato ligand with AgOTf (OTf = OSO2CF 3) afforded quantitatively a single product, i.e., the 16-electron iridiumetriflato complex Ir{κ3(Si,O,Si)-xantsil}(PCy 3)(OTf) (3). 1a + 1b and 16-electron complex 2 are interconvertible via oxidative addition of dihydrogen (from 1a + 1b to 2) and alkene hydrogenation (from 2 to 1a + 1b). Complexes 1a + 1b and 2 were found to catalyze hydrogenation of 3,3-dimethylbut-1-ene.
AB - Synthesis, structure determination, and reactions of a 14-electron four-coordinate iridium(III) complex bearing a xanthene-based bis(silyl) chelate ligand, i.e., Ir{κ2(Si,Si)-xantsil}(PCy3)Cl (1a, xantsil = (9,9-dimethylxanthene-4,5-diyl)bis(dimethylsilyl)), are reported. A precursor of 1a, the 16-electron (dihydrido)iridium(V) complex Ir{κ2 (Si,Si)-xantsil}(H)2(PCy3)Cl (2), was prepared by the reaction of [IrCl-(coe)2]2 (coe = cyclooctene) with 4,5-bis(dimethylsilyl)-9,9-dimethylxanthene (xantsilH2) and PCy 3. Dehydrogenation reaction of 2 with 3,3-dimethylbut-1-ene, a hydrogen acceptor, afforded a mixture of 1a and its isomer 1b, abbreviated as 1a + 1b, together with 2,2-dimethylbutane. Single crystals obtained from a CH 2Cl2 solution of 1a + 1b contained only isomer 1a. X-ray crystal structure analysis of one of the crystals revealed that 1a adopts a distorted seesaw-shaped four-coordinate geometry where the coordinatively unsaturated metal center is stabilized by weak agostic interaction of two γ-C-H bonds of the PCy3 ligand. On the other hand, NMR spectroscopic analysis of 1a + 1b demonstrated that 1a is in fast equilibrium with a minor amount of 1b in solution. Replacement of the chloro ligand in complexes 1a + 1b by a triflato ligand with AgOTf (OTf = OSO2CF 3) afforded quantitatively a single product, i.e., the 16-electron iridiumetriflato complex Ir{κ3(Si,O,Si)-xantsil}(PCy 3)(OTf) (3). 1a + 1b and 16-electron complex 2 are interconvertible via oxidative addition of dihydrogen (from 1a + 1b to 2) and alkene hydrogenation (from 2 to 1a + 1b). Complexes 1a + 1b and 2 were found to catalyze hydrogenation of 3,3-dimethylbut-1-ene.
KW - 14-Electron complex
KW - Alkene hydrogenation
KW - Bis(silyl) chelate ligand
KW - Iridium
KW - Seesaw-shaped complex
KW - Xanthene-based ligand
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U2 - 10.1016/j.jorganchem.2013.09.009
DO - 10.1016/j.jorganchem.2013.09.009
M3 - Article
AN - SCOPUS:84893750945
VL - 751
SP - 686
EP - 694
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
SN - 0022-328X
ER -