Rapid C–H Bond Activation by a Monocopper(III)–Hydroxide Complex
摘要:
One-electron oxidation of the tetragonal Cu(II) complex [Bu4N][LCuOH] at -80 degrees C generated the reactive intermediate LCuOH, which was shown to be a Cu(III) complex on the basis of spectroscopy and theory (L = N,N'-bis(2;6-diisopropylphenyl)-2,6-pyridinedicarboxamide). The complex LCuOH reacts with dihydroanthracene to yield, anthracene and the Cu(II) complex LCu-(OH2). Kinetic studies showed that the reaction occurs via H-atom abstraction via a second order rate law at high rates (cf. k = 1.1(1) M-1 s(-1) at -80 degrees C, Delta H-double dagger = 5.4(2). kcal mol(-1), Delta S-double dagger = -30(2) eu) and with very large kinetic isotope effects.(cf. k(H)/k(D) = 44 at -770 degrees C). The findings suggest that a Cu(III)-OH moiety is a viable reactant in oxidation catalysis.
Structural Characterization of the [CuOR]<sup>2+</sup> Core
作者:V. Mahesh Krishnan、Dimitar Y. Shopov、Caitlin J. Bouchey、Wilson D. Bailey、Riffat Parveen、Bess Vlaisavljevich、William B. Tolman
DOI:10.1021/jacs.0c13470
日期:2021.3.10
Formal Cu(III) complexes bearing an oxygen-based auxiliary ligand ([CuOR]2+, R = H or CH2CF3) were stabilized by modulating the donor character of supporting ligand LY (LY = 4-Y, N,N′-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamide, Y = H or OMe) and/or the basicity of the auxiliary ligand, enabling the first characterization of these typically highly reactive cores by NMR spectroscopy and X-ray
通过调节支持配体 L Y ( L Y = 4 - Y , N , N '-双(2,6-二异丙基苯基)-2,6-吡啶二甲酰胺, Y = H 或 OMe) 和/或辅助配体的碱度, 能够通过 NMR 光谱和 X 首次表征这些典型的高反应性核- 射线晶体学。观察到苯酚底物在溶液中的寿命延长和 PCET 速率降低。核磁共振光谱证实了S= 0 配合物的基态,X 射线结构显示缩短的 Cu-配体键距离与理论非常吻合。
Reactivity of the copper(<scp>iii</scp>)-hydroxide unit with phenols
作者:Debanjan Dhar、Gereon M. Yee、Todd F. Markle、James M. Mayer、William B. Tolman
DOI:10.1039/c6sc03039d
日期:——
Second-order rateconstants (k) were determined from pseudo first-order and stoichiometric experiments, and follow the trends CF3 < NO2 < Cl < H < Me < OMe < NMe2 and LCuOH < NO2LCuOH. The data support a concerted proton–electron transfer (CPET) mechanism for all but the most acidic phenols (X = NO2 and CF3), for which a more complicated mechanism is proposed. For the case of the reactions between NO2ArOH