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

摘要

Pincer complexes of the types [Pd{C,N,N′-Ar{C(Me)=NOCH _2py-2}-2}X] or [Pd{C,N,S-C _6H _4{C(Me)=NOCH _2SMe}-2}Cl] (Ar = C _6H _4, C _6H(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 XCH _2py-2 or ClCH _2SMe, respectively, in the presence of K ~tBuO. Various neutral and cationic derivatives have been synthesized as well as iminobenzoyl complexes resulting from the insertion of isocyanide into their Pd-C _(aryl) bond. The cycloaddition of MeO _2CC≡CCO _2Me to the oximato complex [Pd{C,N-C _6H _4{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′-C _6H _4{C(Me)=NOC(CO _2Me)=C(CO _2Me)}-2}L]. Complexes of each one of the new types have been characterized by X-ray diffraction methods.