Synthesis and Structure of PdII Complexes Containing the C,C-Chelating Bis-Ylide Ligand [Ph₃PC(H)]₂CO. X-ray Crystal Structure of {Pd(μ-Cl){[C(H)PPh₃]₂CO}}₂(ClO₄)₂·CH₂Cl₂

The reaction of Pd(OAc)(2) with the bis(phosphonium) salt [Ph(3)PCH(2)COCH(2)PPh(3)]Cl(2) (1:1 molar ratio) results in the formation of the cis-dichlorobis(ylide) derivative Cl(2)Pd{[C(H)PPh(3)](2)CO}, 1, in which the bis(ylide) ligand [C(H)PPh(3)](2)CO acts as a chelating group through the two ylide carbon atoms. Complex 1 reacts with TlClO(4) (1:1 molar ratio) to give [Pd(-Cl){[C(H)PPh(3)](2)CO}](2)(ClO(4))(2), 2, which reacts with two further equivalents of TlClO(4) in NCMe to give [Pd{[C(H)PPh(3)](2)CO}(NCMe)(2)](ClO(4))(2) 3. The reactivity of 2 and 3 has been explored. Compound 2 reacts with pyridine, 3,5-lutidine, or Ph(3)P=C(H)CN (1:2 molar ratio), resulting in the rupture of the chlorine bridging system and formation of [PdCl{[C(H)PPh(3)](2)CO}(L)](ClO(4)) (L = py (4), 3,5-lu (5), NC-C(H)=PPh(3) (6)), and with Tlacac (1:2 molar ratio) with formation of the acetylacetonate [Pd(acac){[C(H)PPh(3)](2)CO}](ClO(4)), 7. On the other hand, complex 3 reacts with the ylide Ph(3)P=C(H)CN (1:2 molar ratio) giving [Pd{[C(H)PPh(3)](2)CO}[NC-C(H)=PPh(3)](2)](ClO(4))(2), 8, which contains two N-coordinated ylides, and with NBu(4)OH (1:1) to give [Pd(-OH){[C(H)PPh(3)](2)CO}](2)(ClO(4))(2), 9. The reaction of Pd(OAc)(2) with the ylide phosphonium salt [Ph(3)P=C(H)COCH(2)PPh(3)](ClO(4)) (1:1) gives the acetate dimer [Pd(-OOCCH(3)){[C(H)PPh(3)](2)CO}](2)(ClO(4))(2), 10. The structures of complexes 1-10 were deduced from their spectroscopic data and from the resolution of the molecular structure of complex 2.CH(2)Cl(2).