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首页> 外文期刊>Chemistry: A European journal >Iridium Complexes Containing Mesoionic C Donors: Selective C(sp(3))-H versus C(sp(2))-H Bond Activation, Reactivity Towards Acids and Bases, and Catalytic Oxidation of Silanes and Water
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Iridium Complexes Containing Mesoionic C Donors: Selective C(sp(3))-H versus C(sp(2))-H Bond Activation, Reactivity Towards Acids and Bases, and Catalytic Oxidation of Silanes and Water

机译：含中键碳供体的铱配合物：选择性C（sp（3））-H与C（sp（2））-H键活化，对酸和碱的反应性以及硅烷和水的催化氧化

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摘要

Metalation of a C2-methylated pyridylimidazolium salt with [ IrCp* Cl-2](2) affords either an ylidic complex, resulting from C(sp(3))-H bond activation of the C2-bound CH3 group if the metalation is performed in the presence of a base, such as AgO2 or Na2CO3, or a mesoionic complex via cyclometalation and thermally induced heterocyclic C(sp(2))-H bond activation, if the reaction is performed in the absence of a base. Similar cyclometalation and complex formation via C(sp(2))-H bond activation is observed when the heterocyclic ligand precursor consists of the analogous pyridyltriazolium salt, that is, when the metal bonding at the C2 position is blocked by a nitrogen rather than a methyl substituent. Despite the strongly mesoionic character of both the imidazoly-lidene and the triazolylidene, the former reacts rapidly with D+ and undergoes isotope exchange at the heterocyclic C5 position, whereas the triazolylidene ligand is stable and only undergoes H/D exchange under basic conditions, where the imidazolylidene is essentially unreactive. The high stability of the Ir-C bond in aqueous solution over a broad pH range was exploited in catalytic water oxidation and silane oxidation. The catalytic hydrosilylation of ketones proceeds with turnover frequencies as high as 6 000 h(-1) with both the imidazolylidene and the triazolylidene system, whereas water oxidation is enhanced by the stronger donor properties of the imidazol-4-ylidene ligands and is more than three times faster than with the triazolylidene analogue.
机译：用[IrCp * Cl-2]（2）对C2-甲基化的吡啶并咪唑鎓盐进行金属化，可以得到任何一种叶状配合物，这是由于如果进行金属化，则C2结合的CH3基团的C（sp（3））-H键活化如果反应是在不存在碱的情况下进行的，则在碱（例如AgO2或Na2CO3）或通过环金属化和热诱导的杂环C（sp（2））-H键活化的中离子络合物的存在下进行。当杂环配体前体由类似的吡啶基三唑盐组成时，即当C2位置的金属键被氮而不是氮所阻止时，观察到类似的环金属化和通过C（sp（2））-H键活化形成复合物。甲基取代基。尽管咪唑基和三唑基都具有很强的介电特性，但前者会与D +快速反应并在C5杂环上进行同位素交换，而三唑基配体是稳定的，仅在碱性条件下进行H / D交换。咪唑基亚烷基基本上是不反应的。 Ir-C键在宽pH范围内在水溶液中的高稳定性被用于催化水氧化和硅烷氧化。咪唑基亚砜和三唑基亚砜体系的酮催化加氢硅烷化反应的周转频率高达6 000 h（-1），而咪唑4亚基的强供体性质增强了水的氧化作用，并且该作用要大于比三唑基类似物快三倍。

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