Cyclopalladated complexes derived from benzamidoxime

Abstract

Cyclopalladated benzamidoxime complexes [Pd{C,N-C₆H₄{C(NH₂)NOH}-2}Cl(L)] (L = PTol₃, Tol = C₆H₄Me-4 (2a); XyNC, Xy = C₆H₃Me₂-2,6 (2b); pic, C₅H₄Me-4 (2c)), [Pd{C,N-C₆H₄{C(NH₂)NOH}-2}(L₂)]ClO₄ (L = pic (3a); L₂ = 4,4′-di-tert-butyl-2,2′-bipyridine, tbbpy (3b)) and PPN[Pd{C,N-C₆H₄{C(NH₂)NOH}-2}Cl₂] (4) are prepared by reacting [Pd{C,N-C₆H₄{C(NH₂)NOH}-2}(μ-Cl)]₂ (1) with the appropriate neutral ligand or with [PPN]Cl, respectively. The cationic complexes are obtained in the presence of NaClO₄. The reaction of 2a with K^tBuO affords the dinuclear oximato complex [Pd{μ-C,N,O-C₆H₄{C(NH₂)NO}-2}(PTol₃)]₂ (5) or, in the presence of ClCH₂py·HCl, the pincer derivative [Pd{C,N,N′-C₆H₄{C(NH₂)NOCH₂(C₅H₄N-2)}-2}(PTol₃)]ClO₄ (6). Complex 2b reacts with XyNC to give the iminobenzoyl complex [Pd{C,N-C(NXy)C₆H₄{C(NH₂)NOH}-2}Cl(CNXy)] (7) resulting from the insertion of XyNC into the Pd–C bond. The dinuclear complex [{Pd(tbbpy)}₂{C,N,N′,O-C₆H₄{C(NH)NO}-2}]ClO₄ (8) bearing a bridging tetradentate benzimido(oximate) ligand is obtained by reacting Pd(OAc)₂ with tbbpy and the metal–ligand complex 3b. The crystal structures of complexes 2a, 6, 7 and 8 have been determined.