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Versatility and adaptative behaviour of the P^N chelating ligand MeDalphos within gold(i) π complexes
The hemilabile P^N ligand MeDalphos enables access to a wide range of stable gold(i) π-complexes with unbiased alkenes and alkynes, as well as electron-rich alkenes and for the first time electron-poor ones. All complexes have been characterized by multi-nuclear NMR spectroscopy and whenever possibl...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Royal Society of Chemistry
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8157524/ https://www.ncbi.nlm.nih.gov/pubmed/34084334 http://dx.doi.org/10.1039/c9sc06398f |
Sumario: | The hemilabile P^N ligand MeDalphos enables access to a wide range of stable gold(i) π-complexes with unbiased alkenes and alkynes, as well as electron-rich alkenes and for the first time electron-poor ones. All complexes have been characterized by multi-nuclear NMR spectroscopy and whenever possible, by X-ray diffraction analyses. They all adopt a rare tricoordinate environment around gold(i), with chelation of the P^N ligand and side-on coordination of the alkene, including the electron-rich one, 3,4-dihydro-2H-pyrane. The strength of the N → Au coordination varies significantly in the series. It is the way the P^N ligand accommodates the electronic demand at gold, depending on the alkene. Comparatively, when the chelating P^P ligand (ortho-carboranyl)(PPh(2))(2) is used, gold(i) π-complexes are only isolable with unbiased alkenes. The bonding situation within the gold(i) P^N π-complexes has been thoroughly analyzed by DFT calculations supplemented by Charge Decomposition Analyses (CDA), Natural Bond Orbital (NBO) and Atoms-in-Molecules (AIM) analyses. Noticeable variations in the donation/back-donation ratio, C[double bond, length as m-dash]C weakening, alkene to gold charge transfer and magnitude of the N → Au coordination were observed. Detailed examination of the descriptors for the Au/alkene interaction and the N → Au coordination actually revealed intimate correlation between the two, with linear response of the MeDalphos ligand to the alkene electronics. The P^N ligand displays non-innocent and adaptative character. The isolated P^N gold(i) π-complexes are reactive and catalytically relevant, as substantiated by the chemo and regio-selective alkylation of indoles. |
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