Thanks to the + PCy3 substituents unlikely to undergo intramolecular C−H activation, a Pd(II) complex [(C,C,C)PdCl](OTf) exhibiting the neutral LX2-type NHC, diphosphonium bis(ylide) pincer ligand was selectively prepared by a double deprotonation of the [(NHC)PdCl2(Py)] precursor with tBuOK. The influence on the + PCy3 substituents on the overall electronic properties of this pincer scaffold was evaluated by IR spectroscopy data of the corresponding Pd−CO adduct revealing its stronger electron-donating character compared to the structurally related NHC core pincer bearing + PPh3 extremities. Treatment of the electron-rich pincer complex [(C,C,C)PdCl](OTf) with AgOTf led to the C,C-chelating NHC-phosphonium ylide Pd(II) complex [(C,C)Pd(OTf)Cl](OTf) via the oxidatively induced homolytic cleavage of a Pd−ylide bond. In the presence of stronger base (KHMDS or LDA) cyclometalation of a + P−Cy substituent was observed affording a constraint Pd(II) complex featuring the unique anionic LX3-type C,C,C,C-NHC, diphosphonium tris(ylide) ligand.

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