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

机译：阳离子铱配合物催化亚胺加氢的机理研究

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Complexes [IrH_2(eta~6-C_6H_6)-(PiPr_3)]BF_4(1)and [IrH_2(NCMe)_3-(PiPr_3)]BF_4(2)are catalyst precursors for homogeneous hydrogenation of N-benzylideneaniline under mild conditions.Precursor 1 generates the resting state [IrH_2{eta~5-(C_6H_5)NHCH_2Ph}-(PiPr_3)]BF_4(3),while 2 gives rise to a mixture of [IrH(PhN=CH(C_6H_4)-kappa N,C)(NCMe)_2(PiPr_3)]BF_4(4)and [IrH{PhN=CH(C_6H_4)-kappa N,C}(NCMe)-(NH_2Ph)(PiPr_3)]BF_4(5),in which the aniline ligand is derived from hydrolysis of the imine.The less hindered ben-zophenone imine forms the catalytically inactive,doubly cyclometalated compound [Ir{HN=CPh(C_6H_4)-kappa N,C}_2-(NH_2CHPh_2)(PiPr_3)]BF_4(6).Hydroge-nations with precursor 1 are fast and their reaction profiles are strongly dependent on solvent,concentrations,and temperature.Significant induction periods,minimized by addition of the amine hydrogenation product,are commonly observed.The catalytic rate law(THF)is rate=kappa[l][PhN=CHPh]p(H_2).The results of selected stoichiometric reactions of potential catalytic intermediates exclude participation of the cyclometalated compounds [IrH{PhN=CH(C_6H_4)-kappa N,C}(S)_2(PiPr_3)]BF_4 [S=acetonitrile(4),[D_6]acetone(7),[D_4]methanol(8)]in catalysis.Reactions between resting state 3 and D_2 reveal a selective sequence of deuterium incorporation into the complex which is accelerated by the amine product.Hydrogen bonding among the components of the catalytic reaction was examined by MP2 calculations on model compounds.The calculations allow formulation of an ionic,outer-sphere,bifunctional hydrogenation mechanism comprising 1)amine-assisted oxidative addition of H_2 to 3,the result of which is equivalent to het-erolytic splitting of dihydrogen,2)replacement of a hydrogen-bonded amine by imine,and 3)simultaneous H~(delta+)/H~(delta-)transfer to the imine substrate from the NH moiety of an arene-coor-dinated amine ligand and the metal,respectively.
机译：配合物[IrH_2（eta〜6-C_6H_6）-（PiPr_3）] BF_4（1）和[IrH_2（NCMe）_3-（PiPr_3）] BF_4（2）是在温和条件下N-苄叉亚基苯胺均匀氢化的催化剂前体。 1产生静止状态[IrH_2 {eta〜5-（C_6H_5）NHCH_2Ph}-（PiPr_3）] BF_4（3），而2产生[IrH（PhN = CH（C_6H_4）-kappa N，C）的混合物（NCMe）_2（PiPr_3）] BF_4（4）和[IrH {PhN = CH（C_6H_4）-κN，C}（NCMe）-（NH_2Ph）（PiPr_3）] BF_4（5），其中苯胺配体为受阻较少的苯并偶氮酮亚胺形成催化惰性的双环金属化化合物[Ir {HN = CPh（C_6H_4）-k N，C} _2-（NH_2CHPh_2）（PiPr_3）] BF_4（6）与前体1的氢化反应速度快，并且它们的反应曲线在很大程度上取决于溶剂，浓度和温度。通常观察到显着的诱导期，通过添加胺加氢产物将其最小化。催化速率定律（THF）为速率= kappa [l] [PhN = CHPh] p（H_2）。选定化学计量比r的结果潜在催化中间体的作用不包括环金属化合物[IrH {PhN = CH（C_6H_4）-κN，C}（S）_2（PiPr_3）] BF_4的参与[S =乙腈（4），[D_6]丙酮（7） ，[D_4]甲醇（8）]。在静止状态3和D_2之间的反应揭示了氘结合到配合物中的选择性顺序，该顺序被胺产物加速。MP2检测了催化反应各组分之间的氢键该计算允许制定一种离子型，外层双功能加氢机理，该机理包括：1）胺辅助的H_2氧化加成到3的氧化，其结果等同于二氢的热裂解，2）取代由亚胺形成的氢键合胺，和3）分别由芳烃键位胺配体的NH部分和金属同时将H〜（δ+）/ H〜（δ）同时转移至亚胺底物。

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