From Chelate C,N-Cyclopalladated Oximes to C,N,N′-, C,N,S-, or C,N,C′-Pincer Palladium(II) Complexes by Formation of Oxime Ether Ligands

Pincer complexes of the types [Pd­{C,N,N′-Ar­{C­(Me)NOCH2py-2}-2}­X] or [Pd­{C,N,S-C6H4{C­(Me)NOCH2SMe}-2}­Cl] (Ar = C6H4, C6H­(OMe)3-4,5,6; py-2 = 2-pyridyl; X = Cl, Br) have been prepared by reacting cyclopalladated oxime complexes [Pd­{C,N-Ar­{C­(Me)NOH}-2}­(μ-Cl)]2 with XCH2py-2 or ClCH2SMe, respectively, in the presence of KtBuO. Various neutral and cationic derivatives have been synthesized as well as iminobenzoyl complexes resulting from the insertion of isocyanide into their Pd–Caryl bond. The cycloaddition of MeO2CCCCO2Me to the oximato complex [Pd­{C,N-C6H4{C­(Me)NO}-2}­(tBubpy)] (tBubpy = 4,4′-di-tert-butyl-2,2′-bipyridine) in the presence of various neutral L ligands produces pincer complexes [Pd­{C,N,C′-C6H4{C­(Me)NOC­(CO2Me)C­(CO2Me)}-2}­L]. Complexes of each one of the new types have been characterized by X-ray diffraction methods.