Division of Chemistry and Chemical Engineering, California Institute of Technology (USA); Current address: Department of Chemistry, University of California, Riverside, CA 92521 (USA).
Angew Chem Int Ed Engl. 2014 Jan 20;53(4):1081-6. doi: 10.1002/anie.201308175. Epub 2013 Dec 9.
Bifunctional EH activation offers a promising approach for the design of two-electron-reduction catalysts with late first-row metals, such as Ni. To this end, we have been pursuing H2 activation reactions at late-metal boratranes and herein describe a diphosphine-borane-supported Ni-(H2 ) complex, [((Ph) DPB(iPr) )Ni(H2 )], which has been characterized in solution. (1) H NMR spectroscopy confirms the presence of an intact H2 ligand. A range of data, including electronic-structure calculations, suggests a d(10) configuration for [((Ph) DPB(iPr) )Ni(H2 )] as most appropriate. Such a configuration is highly unusual among transition-metal H2 adducts. The nonclassical H2 adduct is an intermediate in the complete activation of H2 across the NiB interaction. Reaction-coordinate analysis suggests synergistic activation of the H2 ligand by both the Ni and B centers of the nickel boratrane subunit, thus highlighting an important role of the borane ligand both in stabilizing the d(10) Ni-(H2 ) interaction and in the H-H cleavage step.
双功能 EH 活化为设计具有后过渡金属（如 Ni）的两电子还原催化剂提供了一种很有前途的方法。为此，我们一直在研究后过渡金属硼烷的 H2 活化反应，在此描述了一种二膦-硼烷负载的 Ni-(H2 )配合物 [((Ph) DPB(iPr) )Ni(H2 )]，该配合物已在溶液中得到了表征。(1) 1 H NMR 光谱证实存在完整的 H2 配体。一系列数据，包括电子结构计算，表明 [((Ph) DPB(iPr) )Ni(H2 )] 的 d(10)构型最合适。这种构型在过渡金属 H2 加合物中非常罕见。非经典 H2 加合物是 NiB 相互作用中完全活化 H2 的中间产物。反应坐标分析表明，Ni 和镍硼烷亚基的 B 中心协同活化 H2 配体，从而突出了硼烷配体在稳定 d(10)Ni-(H2 )相互作用和 H-H 断裂步骤中的重要作用。
