Reactivity of Pd(II) complexes containing the orthometallated C,C-chelating ligand C6H4-2-PPh2C(H)COCH2PPh3 towards deprotonating reagents. Part 2

The reaction of [Pd(C6H4-2-PPh2C(H)COCH2PPh3)(μ-Cl)]2(ClO4)2 (1) with the deprotonating reagent NBu4OH (1:2.5 molar ratio, room temperature (r.t.)) and subsequently with monodentate ligands L (1:4 molar ratio) or bidentate ligands L–L (1:2 molar ratio) gives the cationic complexes [Pd(C6H4-2-PPh2C(H)COCHPPh3)(L)2](ClO4) (L=PPh3 (2), H2NCH2CHCH2 (3)) or [Pd(C6H4-2-PPh2C(H)COCHPPh3)(LL)](ClO4) (LL=dppm (4), Ph2PCH2PPh2C(H)COPh (5), NC5H4-2-CONPPh3 (6)). In complexes 2–6 the orthometallated-ylide ligand is coordinated through the arylic carbon and through one ylidic carbon, and contains a free ylide fragment C(H)PPh3. The reaction of 1 with NBu4OH (1:2.5 molar ratio, r.t.) and with [PPh2CH2PPh2CH2COMe]ClO4 (1:2 molar ratio) gives [Pd(PPh2CH2PPh2CHC(O)Me)2](ClO4)2 (7) and the ylide–phosphonium salt [Ph3PC(H)COCH2PPh3]ClO4. The reaction seems to occur through protonation of the orthometallated-ylide ligand by the acid protons of the phosphonium unit. All complexes were characterized on the basis of their spectroscopic data.