Phenyl nickel complexes with a chelating P,N ligand. Structures of Ph3P=CHC(=NPh)Ph and [NiPh{Ph2PCH-??C(- ??NPh)Ph}-{Ph3P=CHC(=NPh)Ph-N}]

Article abstract of DOI:10.1039/DT9960003571

The complexes [NiPh{Ph₂PCH-^??C(- ^??NPh)Ph}{Ph₃P=CHC(=NPh)Ph-N}] and [NiPh{Ph₂PCH-^??C(- ^??NPh)Ph}-(PR₃)] (PR₃ = PMe₃, PMe₂Ph or PMePh₂) were prepared starting from [Ni(cod)₂] (cod = cycloocta-1,5-diene) and the phosphorus ylide Ph₃P=CHC(=NPh)Ph I in the presence of a tertiary phosphine. Surprisingly, only the first complex was isolated when PPh₃ and P(C₆H₁₁)₃ were used, whereas the other phosphines led to the corresponding PR₃ complexes together with variable amounts of the first depending on their steric demand. The known synthesis of I has been optimized to yields close to 90%. Experiments carried out to study the potential of the nickel compounds as catalysts for ethylene oligomerization showed the stoichiometric formation of styrene and minor amounts of low-molecular-weight linear α-olefins. The molecular structures of I and the first complex have been determined by X-ray diffraction. In the nickel complex the coordination around the metal is distorted square planar, with P(1)-Ni-C(1) and N(1)-Ni-N(2) angles of 90.30(8) and 97.18(8)°, respectively.

Full text of DOI:10.1039/DT9960003571

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