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Título
E–Z Isomerization of Phosphine-Olefin (PEWO-F4) Ligands Revealed upon PdCl2 Capture: Facts and Mechanism
Año del Documento
2019
Editorial
American Chemical Society
Descripción
Producción Científica
Documento Fuente
Organometallics, 2019, 38, 24, 4701–4707
Resumen
The PEWO phosphines R2P(o-C6H4CH═CHC(O)Ph), R2P(o-C6H2F2CH═CHC(O)Ph), and R2P(o-C6F4CH═CHC(O)Ph) and their P-monodentate complexes trans-[PdCl2(P-monodentate)2] show, in solution and (when 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 as well but are not observed because they are extremely displaced toward the E isomer. Their capture in the form of [PdCl2(P-chelate)], with equilibrium constants on the order Keq ≈ 1–3, allows the two configurations to be observed and isolated. Evaluation of their ability to couple Pf–Pf from cis-[PdPf2(THF)2] (Pf = C6F5) affords values of their ΔG⧧(Pf–Pf)Pd parameters confirming that higher substitution of H by F produces lower coupling barriers and a double bond that is more electron deficient when it is free and more electron withdrawing when it is coordinated.
Palabras Clave
Phosphine
ISSN
0276-7333
Revisión por pares
SI
Patrocinador
Junta de Castilla y León (projects VA051P17 and VA062G18)
Ministerio de Economía, Industria y Competitividad (projects CTQ2016-80913-P and CTQ2017-89217-P)
Ministerio de Economía, Industria y Competitividad (projects CTQ2016-80913-P and CTQ2017-89217-P)
Version del Editor
Propietario de los Derechos
© 2019 American Chemical Society
Idioma
eng
Tipo de versión
info:eu-repo/semantics/acceptedVersion
Derechos
openAccess
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