Palladium( ii ) pincer complexes of a C , C , C -NHC, diphosphonium bis(ylide) ligand

Rachid Taakili (1) , Christine Lepetit (1) , Carine Guyard-Duhayon (1) , Dmitry A. Valyaev (1) , Noël Lugan (1) , Yves Canac (1)

1 LCC - Laboratoire de chimie de coordination

A new family of pincer palladium(ii) complexes bearing an electron-rich C,C,C-NHC, diphosphonium bis(ylide) ligand of LX2-type was prepared through the dual N-functionalization of 1H-imidazole by (3-bromopropyl)triphenylphosphonium bromide. Selected basic conditions allowed the sequential coordination of the NHC and phosphonium ylide moieties to Pd(ii). This strategy led to an original ortho-metallated complex where the Pd center is bonded to four carbon atoms of three different natures: carbenic (sp2), arylic (sp2), and chiral ylidic (sp3). Protonation of the latter afforded NHC, diphosphonium bis(ylide) pincer Pd(ii) complexes as a mixture of meso- and dl-diastereomers (de = 50%). The selectivity of C-coordination was rationalized on the basis of DFT calculations, evidencing the quasi-degeneracy of the two diastereomeric forms.

Mots clés: Carbon ligand; NHC; palladium; phosphonium ylide; pincer complex 2

Domaines: Chimie de coordination

Rachid Taakili, Christine Lepetit, Carine Guyard-Duhayon, Dmitry A. Valyaev, Noël Lugan, et al.. Palladium( ii ) pincer complexes of a C , C , C -NHC, diphosphonium bis(ylide) ligand. Dalton Transactions, 2019, 48 (5), pp.1709-1721. ⟨10.1039/c8dt04316g⟩. ⟨hal-02140710⟩