The catalytic C(sp³)–H deuteration of tricyclohexylphosphine (PCy₃) with excess benzene-d₆ at 60 °C was achieved using the iridium catalyst precursor Ir(κ²Si,Si-xantsil)(H)₂(PCy₃)Cl (1), in the presence of (Me₃Al)₂·DABCO (xantsil = (9,9-dimethylxanthene-4,5-diyl)bis(dimethylsilyl), DABCO = 1,4-diazabicyclo[2.2.2]octane). In this reaction, the 3,5-equatorial and 4-axial C–Hs of PCy₃ were selectively deuterated, chiefly affording P(Cy-d₃)₃. To gain insight into the reaction mechanism, iridium complexes bearing an asymmetric and bulkier bis(silyl)–xanthene chelate ligand with SiMe₂ and Si(p-Tol)₂ coordinating moieties, namely, Ir(κ²Si,Si-xantSi^MeSi^p-Tol)(H)₂(L)Cl (L = pyridine (2-py) or PCy₃ (2-PCy)), were synthesized, and similar reactions using them were examined under stoichiometric and catalytic conditions. The stoichiometric reaction of 2-py with (Me₃Al)₂·DABCO at 60 °C resulted in dehydrochlorination to give the dinuclear complex [Ir(μ-κ¹Si:η⁶,κ¹Si-xantSi^MeSi^p-Tol)(H)]₂ (3). On the other hand, the analogous reaction of 2-PCy in benzene at 60 °C afforded the thermally unstable Ir(xantSi^MeSi^p-Tol)(H)(PCy₃) (4). When this reaction was performed in benzene-d₆, the partially deuterated analogue Ir(xantSi^MeSi^p-Tol)(D)(PCy₃-d_n) (4-D) was formed due to the deuteration of Ir–H and some C(sp³)–Hs of PCy₃ of 4 via H/D exchange with benzene-d₆. Moreover, 2-PCy showed catalytic activity similar to that of 1. On the basis of these results, it is suggested that 4 and 4-D functioned as active species for the catalytic deuteration of PCy₃ using 2-PCy.

中文翻译：

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三环己基膦与苯-d6 的区域选择性和立体选择性 C(sp3)-H 氘化催化剂

使用铱催化剂前体 Ir(κ ² Si,Si -xantsil)(H) ₂ (PCy ₃ )在 60 °C 下使用过量的苯-d ₆实现了三环己基膦 (PCy ₃ )的催化 C(sp ³ )–H 氘化)Cl ( 1 )，在 (Me ₃ Al) ₂ ·DABCO (xantsil = (9,9-二甲基呫吨-4,5-二基)双(二甲基甲硅烷基)，DABCO = 1,4-二氮杂双环[2.2.2 ]辛烷）。在该反应中，PCy ₃的 3,5-赤道和 4-轴 C–Hs被选择性地氘化，主要得到 P(Cy- d ₃ ) ₃. 为了深入了解反应机理，铱配合物带有不对称且体积更大的双（甲硅烷基）-呫吨螯合配体，带有 SiMe ₂和 Si( p -Tol) ₂配位部分，即 Ir(κ ² Si,Si -xantSi ^Me Si合成了^{p- Tol} )(H) ₂ (L)Cl（L = 吡啶（2-py）或 PCy ₃（2-PCy）），并在化学计量和催化条件下检查了使用它们的类似反应。2-py与(Me ₃ Al) ₂的化学计量反应·DABCO在60°C导致脱氯化氢得到双核络合物[Ir(μ-κ ¹ Si :η ⁶ ,κ ¹ Si -xantSi ^Me Si ^{p -Tol} )(H)] ₂ ( 3 )。另一方面，2-PCy在 60 °C 下在苯中的类似反应提供了热不稳定的 Ir(xantSi ^Me Si ^{p -Tol} )(H)(PCy ₃ ) ( 4 )。当该反应在苯-d _{6 中进行时}，部分氘化的类似物 Ir(xantSi ^Me Si ^{p -Tol} )(D)(PCy₃ - d _n ) ( 4-D ) 是由于 Ir-H 和PCy ₃ of 4 的一些 C(sp ³ )-Hs通过与苯-d _{6 的}H/D 交换而形成的。此外，2-PCy表现出与1相似的催化活性。在这些结果的基础上，故建议4和4-d充当用于PCY的催化活性氘化物种₃使用2- PCY。