Arylsulfonylnitrene and arenesulfonyl azide complexes of palladium

Abstract

Reaction of [Pd₂Cl₂(dppm)₂] 1 with arenesulfonyl azides RSO₂N₃ in CH₂Cl₂ at ambient temperature resulted in the formation of dimeric palladium complexes with bridging arylsulfonylnitrene ligands [Pd₂Cl₂(dppm)₂(µ-NSO₂R)] 2 (R = phenyl a, 4-methylphenyl b, 4-nitrophenyl c, 2-nitrophenyl d, 2-naphthyl e or ferrocenyl f). According to their NMR spectra, complexes 2a–2f are typical A-frame adducts, which has been verified by single crystal X-ray diffraction studies on 2d–2f. The short N(1)–S(1) distances [1.541(3)–1.565(3) Å] reflect the double bond character of these bonds and indicate a d_π–p_π interaction of the sulfur atom and the imido nitrogen atom. With 2-nitrobenzenesulfonyl azide a by-product was observed in a yield of 10–15%. Based on spectroscopic properties (¹H and ³¹P NMR, IR) and elemental analysis, this compound contains a bridging arenesulfonyl azide ligand, [Pd₂Cl₂(dppm)₂(µ-2-O₂NC₆H₄SO₂N₃)] 3d. Irradiation with light of λ > 455 nm caused selective dissociation of 3d into 1 and 2-O₂NC₆H₄SO₂N₃. The azide complex 3d is not an intermediate in the formation of the corresponding nitrene complex 2d.