Reversible Inter- and Intramolecular Carbon–Hydrogen Activation, Hydrogen Addition, and Catalysis by the Unsaturated Complex Pt(IPr)(SnBut3)(H)

The complex Pt­(IPr)­(SnBut3)­(H) (1) was obtained from the reaction of Pt­(COD)2 with But3SnH and IPr [IPr = N,N′-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene]. Complex 1 undergoes exchange reactions with deuterated solvents (C6D6, toluene-d8, and CD2Cl2), where the hydride ligand and the methyl hydrogen atoms on the isopropyl group of the IPr ligand have been replaced by deuterium atoms. Complex 1 reacts with H2 gas reversibly at room temperature to yield the complex Pt­(IPr)­(SnBut3)­(H)3 (2). Complex 2 also undergoes exchange reactions with deuterated solvents as in 1 to deuterate the hydride ligands and the methyl hydrogen atoms on the isopropyl group of the IPr ligand. Complex 1 catalyzes the hydrogenation of styrene to ethylbenzene at room temperature. The reaction of 1 with 1 equiv of styrene at −20 °C yields the η2-coordinated product Pt­(IPr)­(SnBut3)­(η2-CH2CHPh)­(H) (3), and with 2 equiv of styrene, it forms Pt­(IPr)­(η2-CH2CHPh)2 (4).

从二(1,5-环辛二烯)合铂[Pt(COD)₂]与三叔丁基氢化锡（But₃SnH）以及IPr（N,N'-双(2,6-二异丙基苯基)咪唑-2-亚基）的反应中，得到了配合物Pt(IPr)(SnBut₃)(H)（化合物1）。配合物1可与氘代溶剂（氘代苯C₆D₆、氘代甲苯-d₈以及二氯甲烷-d₂ CD₂Cl₂）发生氢-氘交换反应，其氢负离子配体与IPr配体异丙基基团上的甲基氢原子均可被氘原子取代。配合物1在室温下可与氢气发生可逆反应，生成配合物Pt(IPr)(SnBut₃)(H)₃（化合物2）。配合物2同样可与氘代溶剂发生类似配合物1的交换反应，使氢负离子配体及IPr配体异丙基的甲基氢原子发生氘代。配合物1可在室温下催化苯乙烯加氢生成乙苯。在-20 ℃条件下，1与1当量苯乙烯反应得到η²配位产物Pt(IPr)(SnBut₃)(η²-CH₂CHPh)(H)（化合物3）；当使用2当量苯乙烯时，则生成配合物Pt(IPr)(η²-CH₂CHPh)₂（化合物4）。