951383-13-4Relevant academic research and scientific papers
Cobalt and nickel complexes bearing pyrazolyliminophosphorane ligands: Synthesis, characterisation and catalytic ethylene oligomerisation behaviour
Zhang, Cheng,Sun, Wen-Hua,Wang, Zhong-Xia
, p. 4895 - 4902 (2006)
Treatment of 1-(2′-azidophenyl)-3,5-dimethylpyrazole (1) with Ph 2PR (R = Ph, Me) and (Ph2P)2CH2, respectively, affords the pyrazolyliminophosphoranes 2, 3 and 4. Reaction of 2 or 3 with [NiCl2(dme)] or NiBr2 yields the N,N-chelate nickel complexes 5-8, and with CoCl2 complexes 9 and 10. Reaction of 4 with [NiCl2(dme)], NiBr2 and CoCl2, respectively, affords the N,N,P-chelate complexes 11-13. Compounds 2-4 were characterised by 1H, 13C, 31P NMR and IR spectroscopy and elemental analysis, while complexes 5-13 were characterised by IR spectroscopy and elemental analysis. The structures of complexes 5, 9 and 12 were further characterised by single-crystal X-ray diffraction techniques. Complexes 5-13 are active catalysts for ethylene oligomerisation upon activation with alkylaluminium derivatives (Et2AlCl, MAO or MMAO). These complexes exhibit good to high catalytic activities (up to 3.54 × 10 6 g mol-1 h atm for the nickel complexes and 5.48 × 105 gmol-1 h atm for the cobalt complexes). The effects of varying ethylene pressure, temperature and aluminium co-catalyst/Ni or Co ratios with complexes 5, 9, 11 and 12 are reported. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
