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首页> 外文期刊>Chemistry: A European journal >Tuning the electronic properties of N-heterocyclic carbenes
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Tuning the electronic properties of N-heterocyclic carbenes

机译：调整N杂环卡宾的电子性质

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摘要

The electron-donating properties of N-heterocyclic carbenes ([N,N'-bis(2,6-dimethylphenyl)imidazol]-2-ylidene and the respective dihydro ligands) with 4,4'-R-substituted aryl rings (4,4'-R=NEt2, OC12H25, Me, H, Br, S(4-tolyl), SO(4-tolyl), SO2(4-tolyl)) were studied. Twelve new Nheterocyclic carbene (NHC) ligands were synthesized as well as the respective iridium complexes [IrCl(cod)-(NHC)] and [IrCl(CO)(2)(NHC)]. Cyclic voltarnmetry (Delta E-1/2) and IR (nu(CO)) can be used to measure the electrondonating properties of the carbene ligands. Modifying the 4-positions with electron-withdrawing substituents (4-R=-SO2Ar, Delta E-1/2=+0.92V) results in NHC ligands with virtually the same electron -donating capacity as a trialkylphosphine in [IrCl(cod)(PCy3)] (Delta E-1/2 =+0.95V), while [IrCl(cod)(NHC)] complexes with 4-R=NEt2 (Delta E-1/2= + 0.59 V) show drastically more cathodic redox potentials and significantly enhanced donating properties.
机译：具有4,4'-R-取代的芳基环的N-杂环卡宾（[N，N'-双（2,6-二甲基苯基）咪唑] -2-亚烷基和相应的二氢配体）的给电子性研究了4，-R ＝ NEt 2，OC 12 H 25，Me，H，Br，S（4-甲苯基），SO（4-甲苯基），SO 2（4-甲苯基））。合成了十二个新的杂环卡宾（NHC）配体以及相应的铱配合物[IrCl（cod）-（NHC）]和[IrCl（CO）（2）（NHC）]。循环伏安法（Delta E-1 / 2）和IR（nu（CO））可用于测量卡宾配体的供电子性能。用吸电子取代基（4-R = -SO2Ar，Delta E-1 / 2 = + 0.92V）修饰4位化合物，得到的NHC配体几乎与[IrCl（cod）中的三烷基膦具有相同的给电子能力（PCy3）]（Delta E-1 / 2 = + 0.95V），而具有4-R = NEt2（Delta E-1 / 2 = + 0.59 V）的[IrCl（cod）（NHC）]络合物显示出明显更多的阴极氧化还原电位和显着增强的捐赠特性。

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