Two formal palladium carbene complexes, [PC-(sp 2 )P]Pd(PR 3 ) (3: R = Me; 4: R = Ph) were isolated and characterized from [PC(sp 3 )H 2 P] ([PC(sp 3 )H 2 P] = bis[2-(diisopropylphosphino)phenyl]methane, i Pr 2 P-C 6 H 4 -CH 2 -C 6 H 4 -P i Pr 2 ). Structural studies and DFT calculations indicate that the interaction between palladium and carbon is best described as a single bond, associated with nucleophilic character at that carbon atom. The characteristics of 3 were probed by reactions with electrophiles (MeI), acids (MeOH and HCl), and paratoluidine.

A series of palladium(ii) persistent radical carbene complexes, [PC˙(sp2)P]PdX (X = Cl, Br, I), was synthesized from the nucleophilic carbene [PC(sp2)P]PdPMe3.

The reactivity of two nucleophilic palladium carbenes, [PC(sp(2))P]Pd(PMe3) and [PC(sp(2))P]Pd(PPh3), where [PC(sp(2))P] = bis[2-(di-iso-propylphosphino)phenyl]methylene, toward the E-H bond activation of Ph4-nEHn (E = Si, Ge; n = 1-3) and pinacolborane (HBpin) is discussed. Unlike previous reports, both types of isomer species, hydride [PC(EHn-1Ph4-n)P]PdH or [PC(Bpin)P]PdH and silyl/germyl [PC(H)P]Pd(EHn-1Ph4-n), were observed depending on the substrate and the phosphine ligand, showing that the polarity of the Pd-C bond can be tuned by the phosphine substituents.