New water-soluble palladium(II) iodide complexes derived from N-protonated or N-alkyl-1,3,5-triaza-7-phosphaadamantanes: Synthesis, crystal structure and catalytic properties in aqua media

Abstract

Reactions of [NH4]2[PdCl4] with N-protonated or N-alkyl-1,3,5-triaza-7-phosphaadamantane iodide salts [PTA-R]I (R=H, Me, Et, nPr, nBu) give the water-soluble palladium(II) complexes of type [PdI3(PTA-R)] in isolated yields of 62–81%. All these compounds have been fully characterized by IR and NMR spectroscopies and elemental analyses. Their molecular structures were confirmed by single crystal X-ray diffraction analysis. The complexes belong to the relatively unusual zwitterionic, coordination compounds. Moreover, they constitute, as far as we are aware, the first reported examples of palladium compounds bearing N-alkyl-1,3,5-triaza-7-phosphaadamantane ligands. The complexes catalyze efficiently Heck reaction of iodobenzene and n-butyl acrylate as well as iodobenzene and substituted styrenes, under mild conditions in water as a solvent.