260251-75-0Relevant academic research and scientific papers
Nickel chelate complexes of 2-alkylphenylphosphanylphenolates: Synthesis, structural investigation and use in ethylene polymerization
Heinicke, Joachim,Koesling, Manuela,Bru?ll, Robert,Keim, Wilhelm,Pritzkow, Hans
, p. 299 - 305 (2007/10/03)
2-Diphenylphosphanyl- and 2-alkylphenylphosphanyl-4-methylphenols 1 or their silyl ethers 2 and equimolar amounts of nickelocene react in benzene preferably to give orange-brown diamagnetic cyclopentadienylnickel chelate complexes [η-CpNi(P(intersection set)O)] (3). Addition of a second equivalent of 1 or 2 affords (RR) and (SS) diastereoisomers of cis- bis(P(intersection set)O-chelates) 4a-c (R = Ph, Me, iPr) or the unsymmetrical cis-bis(P(intersection set)O-chelate) 5, whereas with bulkier substituted derivatives 1d or 2d (R = tBu) the second step is hindered or retarded. The reactivity of 1d remains high towards nickel salts in polar solvents, but in contrast to 1a-c, yielding 4, a sparingly soluble green trans-bis(P-O-chelate) nickel complex 6d is formed. Complexes formed in situ from 1 or 2 and Ni(COD)2 in toluene catalyze the polymerization of ethylene. The cyclopentadienyl (P(intersection set)O) complexes 3, however, are too stable to be active in this process. The crystal and molecular structure of 3c and 4c are described.
