<i>E</i>–<i>Z</i> Isomerization of Phosphine-Olefin (PEWO-F<sub>4</sub>) Ligands Revealed upon PdCl<sub>2</sub> Capture: Facts and Mechanism
作者:Marconi N. Peñas-Defrutos、Andrea Vélez、Estefanía Gioria、Pablo Espinet
DOI:10.1021/acs.organomet.9b00679
日期:2019.12.23
available) in the X-ray diffraction structures, an E configuration of the double bond. In contrast, the structures of [PdCl2(P-chelate)] display E and Z configurations. The E/Z isomerization of the latter requires first decoordination of the double bond, which then allows for easy rotation about the electron-deficient double bond. Thus, the E/Z equilibria exist for the free and the P-monodentate complexes
所述PEWO膦- [R 2 P(ø -C 6 ħ 4 CH = CHC(O)PH),R 2 P(ø -C 6 ħ 2 ˚F 2 CH = CHC(O)PH),和R 2 P(ø - ç 6 ˚F 4 CH = CHC(O)PH)和它们的P-单齿络合物反式- [的PdCl 2(P-单齿)2 ]示出了在溶液中和在X射线衍射结构(当可用时),一个è配置双键的。相反,[PdCl 2(P-螯合物)]的结构显示E和Z配置。后者的E / Z异构化需要首先使双键解配位,然后使它容易围绕缺电子的双键旋转。因此,对于游离的和P-单齿的配合物也存在E / Z平衡,但是未观察到,因为它们极易向E异构体位移。它们以[PdCl 2(P-螯合物)]的形式捕获,平衡常数约为K eq≈1-3,可以观察和分离这两种构型。评价它们从顺式-[PdPf 2(THF)2 ]偶联Pf-Pf的能力(Pf = C 6 F5),得到其Δ的值ģ