724428-41-5Relevant academic research and scientific papers
Ortho-5-methylfuran- and benzofuran-substituted η3- allyl(α-diimine)nickel(II) complexes: Syntheses, structural characterization, and the first polymerization results
Ionkin, Alex S.,Marshall, William J.
, p. 3276 - 3283 (2004)
Two representatives of a new family of ortho-furan-substituted N,N-phenyl α-diimine ligands [(Ar-N=C(Me)-(Me)C=N-Ar) Ar = 2,6-bis(5-methylfuran-2- yl)-4-phenylphenyl, 9; Ar = 2,6-bis(benzofuran-2-yl)phenyl, 17] have been synthesized by two alternative synthetic methodologies. 3,5-Bis(5-methylfuran-2- yl)biphenyl-4-ylamine (7) was prepared through a classical pyrylium salt approach. 2,6-Bis(5-methylfuran-2-yl)-4-phenylpyranylium tetrafluoroborate (4) was converted to 2,6-bis(5-methylfuran-2-yl)-4-phenylnitrobenzene (5) by reaction with nitromethane. Reduction of nitro compound 5 by zinc dust afforded aniline 7. The palladium-catalyzed cross-coupling reaction between 2,6-dibromophenylamine 13 and 2-benzofuranboronic acid 14 was used to prepare 2,6-bis(benzofuran-2-yl)phenylamine 15. The condensation of 2,2,3,3- tetramethoxybutane 8 with anilines 7 and 15 afforded α-diimines 9 and 17. The reaction of π-allylnickel chloride dimer 10, α-diimines 9 and 17, and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BAF) (11) or silver hexafluoroantimonate 18 led to three complexes, [η3-allyl(Ar-N= C(Me)-(Me)C=N-Ar)Ni]+X- [Ar = 2,6-bis(5-methylfuran-2-yl)- 4-phenylphenyl, X = BAF, 12, Ar = 2,6-bis(benzofuran-2-yl)phenyl, X = BAF, 19, X = SbF6, 20]. The steric repulsion of closely positioned benzofuran-2-yl groups in 20 caused distortion of the nickel square planar coordination by up to 11.4° according to X-ray analysis. Benzofuran-2-yl groups deviated up to 46.6° from the main planes of central phenyl rings in 20. Complexes 12 and 19 were tested as ethylene polymerization catalysts. The benzofuran-substituted η3-allyl (α-diimine)Ni complexes 19 afforded polyethylene with ultrahigh molecular weights (Mw) and was about three time more productive than complex 12.
