New Derivatives of PCP-Type Pincer Complexes of Nickel

The pincer-type complexes (PCsp3Pi-Pr)NiR (PCsp3Pi-Pr = (i-Pr2PCH2CH2)(2)CH) react with HBF4 (R = C equivalent to CMe, Ph, Me) or AgBF4 (R = Br) to give (PCsp3 Pi-Pr)Ni(BF4), 1, which was found to involve fluxional Ni-F-BF3 interactions. Competition experiments revealed that the relative ease of protonation of the Ni-hydrocarbyl moiety follows the order Ni-Me > Ni-C equivalent to CMe > Ni-Ph. Complex 1 reacts with water to give [(PCsp3Pi-Pr)Ni(H2O)][BF4], 2, that in turn undergoes H2O exchange with CH3CN, i-PrNH2, and CO to give the corresponding cationic adducts 3, 4, and 5; alternatively, 3-5 can also be obtained directly from the reaction of 1 with CH3CN, i-PrNH2, and CO, respectively. Deprotonation of complex 2 gives the neutral hydroxo complex (PCsp3Pi-Pr)Ni(OH), 6. All complexes have been characterized by NMR spectroscopy and, in the case of 2-6, by X-ray crystallography.

钳型配合物(PCsp3Pi - Pr)NiR（PCsp3Pi - Pr = (i - Pr2PCH2CH2)(2)CH；R = 乙炔基甲基、苯基、甲基）与HBF4（R = 乙炔基甲基、苯基、甲基）或AgBF4（R = 溴）反应生成(PCsp3Pi - Pr)Ni(BF4)（1），发现其存在动态的Ni - F - BF3相互作用。竞争实验表明，Ni - 烃基部分质子化的相对难易程度遵循Ni - Me > Ni - C≡CMe > Ni - Ph的顺序。配合物1与水反应生成[(PCsp3Pi - Pr)Ni(H2O)][BF4]（2），后者进而与CH3CN、i - PrNH2和CO发生H2O交换，生成相应的阳离子加合物3、4和5；或者，3 - 5也可分别由1与CH3CN、i - PrNH2和CO直接反应得到。配合物2去质子化生成中性羟基配合物(PCsp3Pi - Pr)Ni(OH)（6）。所有配合物都通过核磁共振波谱进行了表征，对于2 - 6，还通过X射线晶体学进行了表征。