Search results for "vanadium complex"
showing 7 items of 7 documents
Vanadium complex with tetradentate [O,N,N,O] ligand supported on magnesium type carrier for ethylene homopolymerization and copolymerization
2010
Immobilization of 1,2‐cyclohexylenebis(5‐chlorosalicylideneiminato)vanadium dichloride on the magnesium support obtained in the reaction of MgCl2·3.4EtOH with Et2AlCl gives a highly active precursor for ethylene homopolymerization and its copolymerization with 1‐octene. This catalyst exhibits the highest activity in conjunction with MAO, but it is also highly active with AlMe3 as a cocatalyst. On the other hand, when combined with chlorinated alkylaluminum compounds, Et2AlCl and EtAlCl2, it gives traces of polyethylene. Moreover, its catalytic activity is strongly affected by the reaction temperature: it increased with rising polymerization temperature from 20 °C to 60 °C. The kinetic curve…
Dichlorovanadium (IV) complexes with salen‐type ligands for ethylene polymerization
2008
Vanadium complexes with tetradentate salen‐type ligands were first time explored in ethylene polymerizations. The effects of the vanadium complex structure, the alkyl aluminum cocatalysts type (EtAlCl2, Et2AlCl, Et3Al, and MAO), and the polymerization conditions (Al/V molar ratio, temperature) on polyethylene yield were explored. It was found that EtAlCl2 in conjunction with investigated vanadium complexes produced the most efficient catalytic systems. It was shown, moreover, that the structural changes of the tetradentate salen ligand (type of bridge which bond donor nitrogen atoms and type of substituent on aryl rings) affected activity of the catalytic system. The complexes containing li…
Impact of Vanadium Complexes with Tetradentate Schiff Base Ligands on the DPPC and EYL Liposome Membranes: EPR Studies
2023
This paper investigates the effect of three vanadium complexes with Schiff base-type tetradentate ligands of general formula N,N′-1,2-cyclohexylenebis(3,5-dichlorosalicylideneiminate) (V1); LVCl2 (L = N,N′-1,2-cyclohexylenebis(5-chlorosalicylideneiminate) (V2); and N,N′-1,3propylenebis (salicylideneiminate) (V3) on the fluidity of liposome membranes obtained by the sonication of natural lecithin (EYL) and synthetic lecithin (DPPC). The study was carried out with TEMPO and 16DOXYL spin probes using the EPR technique. The results show that the effect of the complexes on the fluidity of liposomes whose membranes are in the liquid crystalline phase is much stronger as compared to the liposome m…
Ethylene homo- and copolymerization catalyzed by vanadium, zirconium, and titanium complexes having potentially tridentate Schiff base ligands
2021
Abstract New potentially tridentate Schiff base ligands, 2-[({4-[(3-N,N-dimethylamino)propyl] phenyl}imino)methyl]-4,6-di-tert-butylphenol (L1H) and 2-[{2-(N-phenyl-N-methylaminomethyl)-phenylimino}-methyl]-4,6-di-tert-butylophenol (L2H) were prepared and after deprotonation they were reacted with VOCl3 or MCl4 (where M = Zr or Ti) to produce corresponding complexes (L1-V, L2-V, L1-Zr, L2-Ti) with good yields. All new compounds were characterized by the 1H and 13C NMR as well as FTIR spectroscopic methods. Upon activation with Et2AlCl or EtAlCl2, both the vanadium complexes exhibited exceptionally high catalytic activities in the ethylene polymerization (up to 69,000 kg/(molV⋅h) for L1-V an…
Synthesis and olefin homo- and copolymerization behavior of new vanadium complexes bearing [OSSO]-type ligands
2017
Novel vanadium complexes bearing [OSSO]-type ligands having two phenolato units linked through the –CH2S(CH2)4SCH2– (1V) or –CH2S(CH2)2SCH2– (2V) bridge are synthesized with good yields by reacting a deprotonated ligand with VCl4. They are then used in ethylene (co)polymerization after activation with EtAlCl2 and Et2AlCl. In the presence of EtAlCl2, both complexes promote ethylene polymerization with very high activities, over 4 × 107 g/(mol h), leading to PEs with high molecular weight and narrow molecular weight distribution. The prepared complexes exhibit lower activity for ethylene/1-octene copolymerization. It is also revealed that the catalyst based on the –CH2S(CH2)4SCH2– bridged com…
Ethylenebis(5‐chlorosalicylideneiminato)vanadium dichloride immobilized on MgCl2‐based supports as a highly effective precursor for ethylene polymeri…
2009
Ethylenebis(5‐chlorosalicylideneiminato)vanadium dichloride supported on MgCl2(THF)2 or on the same carrier modified by EtnAlCl3−n, where n = 1–3, was used in ethylene polymerization in the presence of MAO or a common alkylaluminium compounds as a cocatalyst. The support type alter vanadium loading and also change the characteristic of the catalytic active sites. Et2AlCl is the best activator for a catalyst which has been immobilized on a nonmodified support, whereas the systems which contain a carrier which has been modified by an organoaluminium compound reveal the highest activity in conjunction with MAO. That difference, together with different temperature effects on polymerization effi…
Ring opening polymerization of ε-caprolactone initiated by titanium and vanadium complexes of ONO-type schiff base ligand
2021
AbstractA phenoxy-imine proligand with the additional OH donor group, 4,6-tBu2-2-(2-CH2(OH)-C6H4N = CH)C6H3OH (LH2), was synthesized and used to prepare group 4 and 5 complexes by reacting with Ti(OiPr)4 (LTi) and VO(OiPr)3 (LV). All new compounds were characterized by the FTIR, 1H and 13C NMR spectroscopy and LTi by the single-crystal X-ray diffraction analysis. The complexes were used as catalysts in the ring opening polymerization of ε-caprolactone. The influence of monomer/transition metal molar ratio, reaction time, polymerization temperature as well as complex type was investigated in detail. The complexes showed high (LTi) and moderate (LV) activity in ε-caprolactone polymerization a…