Synthesis and Structure of Pd(II) Complexes Containing the C,C-Chelating Bis-Ylide Ligand [Ph(3)P=C(H)](2)CO. X-ray Crystal Structure of {Pd(&mgr;-Cl){[C(H)PPh(3)](2)CO}}(2)(ClO(4))(2).CH(2)Cl(2).

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)CO}, 1, in which the bis(ylide) ligand C(H)PPh(3)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(&mgr;-Cl){C(H)PPh(3)CO}(ClO(4))(2), 2, which reacts with two further equivalents of TlClO(4) in NCMe to give Pd{C(H)PPh(3)CO}(NCMe)(2)(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)CO}(L) (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)CO}, 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)CO}NC-C(H)=PPh(3)(2), 8, which contains two N-coordinated ylides, and with NBu(4)OH (1:1) to give Pd(&mgr;-OH){C(H)PPh(3)CO}(ClO(4))(2), 9. The reaction of Pd(OAc)(2) with the ylide phosphonium salt Ph(3)P=C(H)COCH(2)PPh(3) (1:1) gives the acetate dimer Pd(&mgr;-OOCCH(3)){C(H)PPh(3)CO}(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).