title: A new vanadium (III) complex of 2,6-bis(3,5-diphenylpyrazol-1-ylmethyl)pyridine as a catalyst for ethylene polymerization.
abstract: The tridentate ligand 2,6-bis(3,5-diphenylpyrazol-1-ylmethyl)pyridine, abbreviated as 2,6-[(3,5-ph₂pz-CH₂)₂-py], a new pyridine-pyrazole derivative, was prepared from 2,6-bis(bromomethyl)pyridine and 3,5-diphenylpyrazole. The ligand was characterized by means of elemental analyses, ATR-IR, ¹H- and ¹³C-NMR spectroscopy and single crystal X-ray crystallography. Using this ligand, a new mononuclear vanadium (III) complex, {2,6-[(3,5-ph₂pz)CH₂]₂py}VCl₃ was prepared and characterized by elemental analysis, ATR-IR and HR-MS. The complex was investigated as a catalyst for ethylene polymerization and compared with 2,6-[(3,5-Me₂pz)CH₂]₂py}VCl₃ to explore the effect of the substituent on the pyrazolyl rings on ethylene polymerization. High catalytic activity was observed at ambient temperature. After treatment with AlEtCl₂, these complexes showed high activity for ethylene polymerization converting ethylene to highly linear polyethylene and affording high molecular weight polymers (up to 1.0 × 10⁶ g/mol) with unimodal molecular weight distributions.
authors.affiliation: Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa. habbo@uwc.ac.za
authors.forename: Hanna S
authors.initials: HS
authors.lastname: Abbo
authors.forename: Salam J J
authors.initials: SJ
authors.lastname: Titinchi
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D005030:Ethylenes / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D058105:Polymerization; D011720:Pyrazoles / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D014639:Vanadium / Q000737:chemistry*
chemical_list: D005030:Ethylenes; D008024:Ligands; D011720:Pyrazoles; D011725:Pyridines; D014639:Vanadium; C031280:pyrazole; C036216:ethylene