Remote binding of B(C₆F₅)₃ to (PPO)PdMeL (L = pyridine or lutidine) or {(PPO)PdMe}₂ ethylene polymerization catalysts that contain phosphine-arenephosphinate or phosphine-arenephosphonate ligands (PPO^– = [1-PAr₂-2-PR′O₂-Ph]⁻: Ar = R′ = Ph (1a); Ar = Ph, R′ = OEt (1b); Ar = Ph, R′ = OⁱPr (1c); Ar = 2-OMe-Ph, R′ = OⁱPr (1d)) significantly increases the catalyst activity and the molecular weight of the polyethylene (PE) product. In the most favorable case, in situ conversion of (1d)PdMe(py) to the base-free adduct {1d·B(C₆F₅)₃}PdMe increases the ethylene polymerization activity from 9.8 to 5700 kg mol^–1 h^–1 and the M_n of the PE product from 9030 to 99 200 Da (80 °C, 410 psi). X-ray structural data, trends in ligand lability, and comparative studies of BF₃ activation suggest that these allosteric effects are primarily electronic in origin. The B(C₆F₅)₃ binding enhances the chain growth rate (R_growth) by increasing the degree of positive charge on the Pd center. This effect does not result in the large increase in the chain transfer rate (R_transfer) and concomitant reduction in PE molecular weight seen in previous studies of analogous (PO)PdRL catalysts that contain phosphine-arenesulfonate ligands, because of the operation of a dissociative chain transfer process, which is inhibited by the increased charge at Pd.

中文翻译：

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乙烯聚合催化中的变构作用。通过远程键合B（C ₆ F ₅）₃增强膦膦酸酯和膦膦酸酯钯烷基催化剂的性能

B（C ₆ F ₅）₃与（PPO）PdMeL（L =吡啶或二甲基吡啶）或{（PPO）PdMe} _2的乙烯聚合催化剂的远程结合，这些催化剂包含膦-芳烃次膦酸酯或膦-芳烃膦酸酯配体（PPO ^– = [1 -PAr ₂ -2-PR'O ₂ -Ph] ^-：Ar = R'= Ph（1a）; Ar = Ph，R'= OEt（1b）; Ar = Ph，R'= O ⁱ Pr（1c） ; Ar = 2-OMe-Ph，R'= O ⁱ Pr（1d））显着提高了催化剂活性和聚乙烯（PE）产品的分子量。在最有利的情况下，原位（转化1D）PDME（PY），以游离碱加合物{ 1D ·B（C ₆ ˚F ₅）₃ } PDME增加了从9.8乙烯聚合活性来5700千克摩尔^-1 ħ ^-1和中号_Ñ的从9030到99200 Da（80°C，410 psi）的PE产品。X射线结构数据，配体不稳定性趋势以及BF ₃活化的比较研究表明，这些变构作用主要是电子起源的。B（C ₆ F ₅）₃结合提高链增长速率（R_增长），以增加Pd中心的正电荷程度。这种作用不会导致链转移速率（R _transfer）大幅增加，也不会导致PE分子量的降低，这是因为以前的研究中，由于膦基芳烃磺酸盐配位基的存在，类似的（PO）PdRL催化剂含有膦-芳烃磺酸盐配体。离解链转移过程，其受Pd电荷增加的抑制。