Nickel(0) and Palladium(0) Complexes with 1,3,5-Triaza-7-phosphaadamantane. Catalysis of Buta-1,3-diene Oligomerization or Telomerization in an AqueousBiphasic System
New homoleptic nickel(0) and palladium(0) complexes with a water-soluble ligand, 1,3,5-triaza-7-phosphaadamantane, were prepared and characterized by 1H, 13C, and 31P NMR spectra. The complexes, together with the known analogous Ni(0) and Pd(0) complexes with tris(hydroxymethyl)phosphine, were found to be catalysts for buta-1,3-diene oligomerization or telomerization with water in an aqueous biphasic system without a cosolvent or a modifier. Tetrakis[tris(hydroxymethyl)phosphine]nickel (7) preferentially catalyzes oligomerization (both linear and cyclic) in the first example of a nickel-catalyzed buta-1,3-diene oligomerization in an aqueous biphasic system. Palladium complexes give telomers or linear oligomers in quantitative yields. In the case of the triazaphosphaadamantane complex 4, high selectivity to octadienyl ethers (87%) was observed. High values of metal leaching into the product phase in these reactions suggest an easy extraction of starting or intermediate metal complexes caused by the fact that both monomer and products are good ligands for the metal complexes in this particular case.
