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.

Transition metal complexes of a hydrazone–oxime ligand containing the isonicotinoyl moiety: Synthesis, characterization and microbicide activities

“…The ligand and its metal complexes were analysed for C, H, N, Cl and S at the Micro-analytical Laboratory, Cairo University, Egypt. 1 H NMR (600 MHz) and 13 C NMR (150 MHz) spectra were recorded in DMSO-d 6 with Bruker Avance 600-DRX spectrometers. Chemical shifts (δ) are reported in ppm using tetramethylsilane as the internal standard (NMR laboratory, University of Jeddah, Saudi Arabia).…”

“…Ligands containing the pyridyl moiety and their complexes have attracted much attention owing to their special structure . For example a V 3+ complex catalyses ethylene polymerization . In addition, polymeric complexes of isonicotinic acid hydrazide shows anti‐tuberculosis effects, while isonicotinic Cu 2+ complexes possess antiviral activity .…”

“…[11,12] For example a V 3+ complex catalyses ethylene polymerization. [13] In addition, polymeric complexes of isonicotinic acid hydrazide shows anti-tuberculosis effects, [14] while isonicotinic Cu 2+ complexes possess antiviral activity. [15] Moreover, the toxicity of a Zn 2+ complex with mycobactericidal drug isoniazid (isonicotinohydrazide) is nearly 8.5 times greater than that of isonicotinohydrazide itself against Artemia salina.…”

Metal–Organic Gels Derived from Iron(III) and Pyridine Ligands: Morphology, Self‐Healing and Catalysis for Ethylene Selective Dimerization

“…With increasing the n(Al)/n(Fe) ratio from 250, 500 to 1000 (Entry 8, 6 and 9), the catalytic activity of Fe‐N‐ 20 achieved a maximum value at n(Al)/n(Fe) ratio of 500, reaching 1.48×10 5 g/(mol h), but dropped to 0.85×10 5 g/(mol h) at n(Al)/n(Fe) ratio of 1000. Sufficient Et 2 AlCl was indispensable to approach high activity through the alkylation and activation of Fe III sites, however, excess of Et 2 AlCl might induce the decrease in activity, possibly because too many aluminum impurities created by the Et 2 AlCl cocatalyst might cover the active sites and degrade the catalyst system . In this reaction, Et 2 AlCl possibly played a role as chain transfer agent simultaneously, which inhibited the chain growth and promoted the selectivity of dimerization.…”

“…Sufficient Et 2 AlCl was indispensable to approach high activity throught he alkylation and activation of Fe III sites, however,e xcess of Et 2 AlCl might induce the decrease in activity,p ossibly because too many aluminum impurities created by the Et 2 AlCl cocatalyst might cover the active sites and degrade the catalyst system. [29] In this reaction, Et 2 AlCl possibly played ar olea sc hain transfer agent simultaneously,w hich inhibited the chain growth and promoted the selectivityo fd imerization. Therefore, the oligomerization products of Fe-N catalystw ere most of C 4 with a small amount of C 6 ,C 8 and C 10 + olefins.A mongt hem, the content of C 4 could reach as high as 90 %, showing the dimerization of ethylene was the predominantr eaction.…”