New Palladium(II) Complexes with a Tridentate PNO Ligand

The synthesis of neutral and cationic palladium complexes containing the tridentate monoanionic ligand 2-(2-Ph₂PC₆H₄-CH=N)C₆H₄O]^? is described. Deprotonation of the Schiff base formed by condensation of 2-(diphenylphosphino)benzaldehyde with 2-aminophenol in the presence of the appropriate palladium precursor (Pd(AcO)₂] or PdCl₂(PhCN)₂]) form the corresponding neutral complexes Pd{2-(2-Ph₂PC₆H₄-CH=N)C₆H₄O}(AcO)] (1) or Pd{2-(2-Ph₂PC₆H₄-CH=N)C₆H₄O}(Cl)] (2) in good yield. The first reacts smoothly with thiols and activated phenols to give complexes of general formula Pd{2-(2-Ph₂PC₆H₄-CH=N)C₆H₄O}(X)] (X = OC₆F₅ (3), SEt (4), S^tBu (5), SC₆H₅ (6), SC₆H₄-4Me (7), SC₆H₄-4NO₂ (8)). When the chloro complex is treated with silver perchlorate and tertiary phosphines (L) the cationic derivatives Pd{2-(2-Ph₂PC₆H₄-CH=N)C₆H₄O}(L)]ClO₄] (L = PPh₃ (9), PMePh₂ (10), PMe₂Ph (11), PEt₃ (12)) were obtained. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, ¹H, ¹⁹F and ³¹P NMR).