Stoichiometric reactions of methylparathion with a palladium aryl oxime metallacycle

Abstract

The reaction of [Pd₃(OAc)₆] with (E)-acetophenone oxime and pyridine in CHCl₃ under reflux affords the metallacycle [Pd(OAc){C,N-(C₆H₄C(CH₃)NOH)-2}(py)] (1) as a yellow air-stable complex. The same reaction carried out at room temperature in the absence of pyridine affords the trinuclear oximato complex [Pd(μ-(E)-ONC(CH₃)Ph)(μ-OAc)]₃ (2), which can be converted into 1 upon heating in the presence of pyridine. As indicated by ¹H and ³¹P NMR spectroscopy, complex 1 reacts with methylparathion in acetone-d₆–D₂O solutions to afford [Pd(SP(O)(OCH₃)₂){C,N-(C₆H₄C(CH₃)NOH)-2}(py)] (3) and [Pd(μ-SP(O)(OCH₃)₂){C,N-(C₆H₄C(CH₃)NOH)-2}]₂ (4) as well as free p-nitrophenol. Compounds 1–4 have been characterized by single-crystal X-ray analysis, NMR and EA. Compounds 1 and 3 are mononuclear complexes with the acetate and dimethylthiophosphate ligand, respectively, trans from the phenyl group. Compound 2 is a trinuclear complex whose structure can be derived from that of [Pd₃(OAc)₆] by replacing three of the acetate ligands on one side of Pd₃ plane by three N,O-coordinated oximate ligands. Complex 4 is a dinuclear complex in which the two square-planar palladium moieties are linked by the sulfur atoms of the bridging dimethylthiophosphate ligands.