Phosphine-NHC-Phosphonium Ylide Pincer Ligand: Complexation with Pd(II) and Unconventional P-Coordination of the Ylide Moiety - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Inorganic Chemistry Année : 2023

Phosphine-NHC-Phosphonium Ylide Pincer Ligand: Complexation with Pd(II) and Unconventional P-Coordination of the Ylide Moiety

Résumé

An efficient synthesis of two pincer pre-ligands [Ph2PCH(R)ImCH2CH2CH2PPh3]X2 (R = H, X = OTf; R = Ph, X = BF4) was developed. Subsequent reactions with PdCl2 and an excess of Cs2CO3 lead to the formation of highly stable cationic orthometalated Pd(II) complexes [(P,C,C,C)Pd]X exhibiting phosphine, NHC, phosphonium ylide and σ-aryl donor extremities. The protonation of one of the latter complexes with R = H affords the Pd(II) complex [(P,C,C)Pd(MeCN)](OTf)2 bearing an unprecedented nonsymmetrical NHC core pincer scaffold with a 5,6-chelating framework. The overall donor properties of this phosphine-NHCphosphonium ylide ligand were estimated using experimental nCN stretching frequency in the corresponding [(P,C,C)Pd(CNtBu](OTf)2 derivative and was shown to be competitive with related bis(NHC)-phosphonium ylide and phenoxy-NHC-phosphonium ylide pincers. The presence of a phenyl substituent in the bridge between phosphine and NHC moieties in orthometalated complex [(P,C,C,C)Pd](BF4) makes possible the deprotonation of this position using LDA to provide a persistent zwitterionic complex [(P,C,C,C)Pd] featuring a rare P-coordinated phosphonium ylide moiety in addition to a conventional C-coordinated one. The comparison of the 31P and 13C NMR data for these C- and P-bound phosphonium ylide fragments within the same molecule was performed for the first time and the bonding situation in both cases was studied in detail by QTAIM and ELF topological analyses.
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Dates et versions

hal-04284085 , version 1 (14-11-2023)

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Mohammad Ameskal, Rachid Taakili, Ekaterina S Gulyaeva, Carine Duhayon, Jérémy Willot, et al.. Phosphine-NHC-Phosphonium Ylide Pincer Ligand: Complexation with Pd(II) and Unconventional P-Coordination of the Ylide Moiety. Inorganic Chemistry, 2023, 62 (49), pp.20129-20141. ⟨10.1021/acs.inorgchem.3c03025⟩. ⟨hal-04284085⟩
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