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首页> 外文期刊>Chemistry: A European journal >Mechanistic Investigations of Imine Hydrogenation Catalyzed by Dinuclear Iridium Complexes
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Mechanistic Investigations of Imine Hydrogenation Catalyzed by Dinuclear Iridium Complexes

机译：双核铱配合物催化亚胺加氢的机理研究

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Treatment of [Ir_2(mu-H)(mu-Pz)_2H_3(NCMe)(PiPr_3)_2](1)with one equivalent of HBF_4 or [PhNH=CHPh]BF_4 affords efficient catalysts for the homogeneous hydrogenation of N-benzylideneaniline.The reaction of 1 with HBF_4 leads to the trihydride-dihydrogen complex [Ir_2(mu-H)(mu-Pz)_2H_2-(eta~2-H_2)(NCMe)(PiPr_3)_2]BF_4(2),which has been characterized by NMR spectroscopy and DFT calculations on a model complex.Complex 2 reacts with imines such as tBuN=CHPh or PhN=CHPh to afford amine complexes [Ir_2-(mu-H)(mu-Pz)_2H_2(NCMe){L}(PiPr_3)_2]BF_4(L= NH(rBu)CH_2Ph, 3;NH(Ph)CH_2Ph,4)through a sequence of proton-and hydride-transfer steps.Dihydrogen partially displaces the amine ligand of 4 to form 2;this complements a possible catalytic cycle for the N-benzylideneaniline hydrogenation in which the amine-by-dihydrogen substitution is the turnover-determining step.The rates of ligand substitution in 4 and its analogues with labile ligands other than amine are dependent upon the nature of the leaving ligand and independent on the incoming ligand concentration,in agreement with dissociative substitutions.Water complex [Ir_2-(mu-H)(mu-Pz)_2H_2(NCMe)(OH_2)-(PiPr_3)_2]BF_4(7)hydrolyzes N-benzyli-deneaniline,which eventually affords the poor hydrogenation catalyst [Ir_2(mu-H)(mu-Pz)_2H_2(NCMe)(NH_2Ph)-(PiPr_3)_2]BF_4(11).The rate law for the catalytic hydrogenation in 1,2-dichloro-ethane with complex [Ir_2(mu-H)(mu-Pz)_2H_2(OSO_2CF_3)(NCMe)(PiPr_3)_2](8)as catalyst precursor is rate=kappa[8]{p(H_2)};this is in agreement with the catalytic cycle deduced from the stochiometric experiments.The hydrogenation reaction takes place at a single iridium center of the dinuclear catalyst,although ligand modifications at the neighboring iridium center provoke changes in the hydrogenation rate.Even though this catalyst system is also capable of effectively hydroge-nating alkenes,N-benzylideneaniline can be selectively hydrogenated in the presence of simple alkenes.
机译：用一当量的HBF_4或[PhNH = CHPh] BF_4处理[Ir_2（mu-H）（mu-Pz）_2H_3（NCMe）（PiPr_3）_2]（1），可提供有效的催化剂用于N-苄叉亚基苯胺的均匀加氢。 1与HBF_4的反应生成三氢化物-二氢络合物[Ir_2（mu-H）（mu-Pz）_2H_2-（eta〜2-H_2）（NCMe）（PiPr_3）_2] BF_4（2）复合物2与亚胺类化合物如tBuN = CHPh或PhN = CHPh反应，得到胺络合物[Ir_2-（mu-H）（mu-Pz）_2H_2（NCMe）{L} （PiPr_3）_2] BF_4（L = NH（rBu）CH_2Ph，3; NH（Ph）CH_2Ph，4）。二氢部分取代了4的胺配体，形成2;补充了N-亚苄基苯胺加氢的可能催化循环，其中胺被二氢取代是决定周转的步骤.4及其类似物被胺以外的不稳定配体取代的配体的速率取决于其性质。利维ng配体且与输入配体浓度无关，与解离取代一致。水络合物[Ir_2-（mu-H）（mu-Pz）_2H_2（NCMe）（OH_2）-（PiPr_3）_2] BF_4（7）水解N -苄基-二苯胺，最终提供了不良的氢化催化剂[Ir_2（mu-H）（mu-Pz）_2H_2（NCMe）（NH_2Ph）-（PiPr_3）_2] BF_4（11）。以[Ir_2（mu-H）（mu-Pz）_2H_2（OSO_2CF_3）（NCMe）（PiPr_3）_2]（8）作为催化剂前体的1,2-二氯乙烷的比率为kappa [8] {p（H_2 ）};这与化学计量实验得出的催化周期一致。加氢反应在双核催化剂的单个铱中心发生，尽管相邻铱中心的配体修饰引起了加氢速率的变化。催化剂体系还能够有效地使烯烃加氢，在简单的烯烃存在下，N-苄叉基苯胺可以选择性地氢化。

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