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http://hdl.handle.net/2445/173399
Title: | Pyridine- and quinoline-derived mines as N,N‑bidentate directing groups in palladium versus platinum C−H bond activation reactions |
Author: | Torralvo Martín, Héctor Albert Mach, Joan Ariza Piquer, Xavier Font Bardia, Ma. Mercedes García Gómez, Jordi Granell Sanvicente, Jaime Ramón Martínez López, Manuel, 1957- |
Keywords: | Platí Compostos orgànics Nitrogen Platinum Organic compounds Nitrogen |
Issue Date: | 12-Jan-2021 |
Publisher: | American Chemical Society |
Abstract: | The C-H activation by Pd(II) and Pt(II) compounds of a wide range of imines related to 2-pyridinecarboxaldehyde, ArCH═NCH2(CH2)nPh (Ar = 2-pyridinyl, 2-picolinyl, 2-quinolinyl, n = 0, 1), which can be useful for bond functionalization assisted by bidentate directing groups, has been studied. The results indicate that the presence of two methyl groups at the α-carbon, relative to the imine nitrogen atom, facilitates the metalation. The heterocyclic fragment of the chelating ligand also shows a relevant influence on the full process, the cyclometalated compounds being more easily formed for the 2-picolinyl than for the 2-quinolinyl derivatives, while for the 2-pyridinyl derivatives the reaction is less favored. These effects have been found to be determinant for both palladium and platinum compounds. The preparative results can be explained by a steric enhancement of the metalation process, the reaction being strongly favored when bulky substituents are located in the proximity (α-carbon) of the coordinating nitrogen atoms (with both palladium and platinum). Furthermore, surprisingly the formation of six-membered platinacycles is especially favored. The kinetico-mechanistic studies of the C-H activation reaction, on some equivalent Pd(II) and Pt(II) coordination complexes of the family, have shown that the nature of the d8 metal center plays a determinant role in the reactivity observed. In this respect, the Pt(II) square-planar center has been found to be much more involved in the energetics of the reaction than the Pd(II) equivalent. The full process can be seen as a mechanistic continuum that goes from an electrophilic substitution (Pd(II) centers) to an oxidative addition/reductive elimination sequence (Pt(II) centers). The observation is directly associated with the fact that the Pt(II) center is prone to the existence of oxidatively added Pt(IV) hydrido complexes. |
Note: | Versió postprint del document publicat a: https://doi.org/10.1021/acs.organomet.0c00703 |
It is part of: | Organometallics, 2021, vol. 40, p. 203-217 |
URI: | http://hdl.handle.net/2445/173399 |
Related resource: | https://doi.org/10.1021/acs.organomet.0c00703 |
ISSN: | 0276-7333 |
Appears in Collections: | Articles publicats en revistes (Química Inorgànica i Orgànica) |
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706324.pdf | 1.18 MB | Adobe PDF | View/Open |
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