Synthesis of a 14-electron iridium(III) complex with a xanthene-based bis(silyl) chelate ligand (xantsil): A distorted seesaw-shaped four-coordinate geometry and reactions leading to 16-electron complexes

Catalysts for Regio- and Stereoselective C(sp3)–H Deuteration of Tricyclohexylphosphine with Benzene-d6 Generated via Dehydrochlorination of Chlorido(dihydrido)iridium Complexes Containing a Xanthene-Based Bis(silyl) Chelate Ligand

“…Observation of C−H Deuteration of PCy 3 in a Dehydrochlorination Reaction of an Iridium−xantsil Complex with a Methylating Reagent. In the course of our investigation to produce a highly active 14-electron species, we tested the abstraction of both the hydrido ligand and the chlorido ligand from Ir(κ 2 Si,Si-xantsil)(H) 2 (PCy 3 )Cl (1), 9 that is, dehydrochlorination, using (Me 3 Al) 2 •DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane) as a methylating reagent. 11 In this reaction, substitution of the chlorido ligand with a methyl ligand followed by C−H reductive elimination of methane was expected to occur and thereby generate a vacant coordination site on iridium.…”

“…These hydrogens, H1 and H2, cap the Si1−Si2−N/ P and Si1−Si2−Cl triangles and occupy positions trans to Cl and N(pyridine)/P(PCy 3 ), respectively. The coordination geometry around iridium is similar to that of the analogous Ir−xantsil complex 1 9 and is supported by the 1 H NMR data for 2-PCy (vide infra). The metal center has a larger space trans to the SiMe 2 coordinating moiety in comparison with that trans to the Si(p-Tol) 2 moiety, and the Si1−Ir− N(pyridine)/P(PCy 3 ) bond angles (134.70(10)°(2-py) and 127.28(6)°(2-PCy)) are considerably wider than the Si2−Ir− N/P angles (102.82(10)°(2-py) and 109.14(6)°(2-PCy)).…”

“…PCy 3 (Strem Chemicals), (Me 3 Al) 2 ·DABCO (Sigma-Aldrich), and BH 3 ·THF (1 M solution in THF, Sigma-Aldrich) were stored under argon in a glovebox. 4-Bromo-2,7-di- tert -butyl-5-dimethylsilyl-9,9-dimethylxanthene, ClSiH­( p -Tol) 2 , [IrCl­(coe) 2 ] 2 , and Ir­(κ 2 Si,Si -xantsil)­(H) 2 (PCy 3 )Cl ( 1 ) were prepared according to previously reported methods.…”

“…We recently reported that regioselective C–H activation of tricyclohexylphosphine (PCy 3 ) occurred during the synthesis of a ruthenium complex bearing a xanthene-based bis­(silyl) chelate ligand: namely, Ru­(κ 3 Si,O,Si -xantsil)­(H)­[PCy 2 (η 3 -C 6 H 8 )] (xantsil = (9,9-dimethylxanthene-4,5-diyl)­bis­(dimethylsilyl)) (Figure b) . In the course of our study on the catalysis of xantsil complexes toward C–H functionalization, an iridium–xantsil complex, Ir­(κ 2 Si,Si -xantsil)­(H) 2 (PCy 3 )Cl ( 1 ), and its derivative were found to catalyze the C­(sp 3 )–H deuteration of PCy 3 via H/D exchange with benzene- d 6 (Figure c) . Herein, we report (i) the synthesis and characterization of iridium complexes bearing a bulkier derivative of xantsil and (ii) the catalytic C–H deuteration of PCy 3 .…”

Coordination Geometrical Effect on Ligand-to-Metal Charge Transfer-Dependent Energy Transfer Processes of Luminescent Eu(III) Complexes

“…16 In particular, there have been a number of studies on the control of the MLCT emission processes of Ir(III) and Ru(II) complexes. 17,18 Recently, the control of the LMCT transition in Fe(II) complexes has also been described. 19 The charge-transfer bands are directly related to the electronic and geometrical structures of the metal complex.…”