Vanadyl C and N-capped tris(phenolate) complexes: influence of pro-catalyst geometry on catalytic activity

Abstract

Vanadyl complexes of C or N-capped tripodal ligands, possessing distorted tetrahedral geometry at vanadium, serve as extremely active, thermally robust pro-catalysts for ethylene homo- and ethylene/propylene copolymerisation, whereas pseudo-octahedral pro-catalysts produce far lower activities.

Oxidovanadium(V) Complexes with Aminoethanol Bis(phenolate) [O,N,O,O′] Ligands: Preparations, Structures, N‐Dealkylation and Condensation Reactions

“…chemical catalysis [18,19] where especially important topics are α-olefin polymerization [20][21][22][23] and oxidation of various species. [10,24,25] Generally, vanadium-based polymerization catalysts have been reported to be less active than titanium ones because they suffer deactivating reduction during the catalysis but some advantages are also reported, for instance the synthesis of high molecular weight polymers with a narrow polydispersity.…”

Ethylene Polymerization Using (Imino)vanadium(V) Dichloride Complexes Containing (Anilido)methyl-pyridine, -quinoline Ligands–Halogenated Al Alkyls Catalyst Systems

“…Moreover, we prepared the adamantylimido complexes containing 2-or 8-(anilidomethyl)-quinoline ligands, V(NAd)Cl 2 [(2,6-Me 2 C 6 H 3 )NCH 2 (C 9 H 6 N)] (2a,3a, Scheme 2), and V(N-2-MeC 6 H 4 )Cl 2 [2-ArNCH 2 (C 5 H 4 N)] complexes (4a,b) and explored reactions with ethylene in the presence of MAO (Table 1) [17]: remarkable effect of the imido ligand toward the selectivity (oligomer, polymer) was observed in the presence of MAO (Table 1, runs 9-12), whereas the reaction products by the quinoline analogues were a mixture of PE and oligomers. Since the reaction products by 1a,b in presence of Et 2 AlCl or Me 2 AlCl were PE, in this paper, we thus explored reactions with ethylene in the presence of halogenated Al alkyls to confirm our hypothesis outlined in Scheme 1, for example in ethylene polymerization by the other vanadium complex catalysts, [18][19][20][21][22][23][24]. Scheme 2.…”

An EPR Study of the V(IV) Species Formed Upon Activation of a Vanadyl Phenoxyimine Polymerization Catalyst with AlR3 and AlR2Cl (R = Me, Et)

“…Systems based on [V(acac) 3 ] and alkylaluminums are used commercially in the production of ethylene-propylene-diene elastomers. [1][2][3][4][5][6][7][8][9][10] Despite the ongoing interest in synthesis of new vanadium polymerization catalysts [11][12][13][14][15][16][17][18] little is known about the reaction mechanism. The main problem is the paramagnetism of alkylvanadium compounds, which precludes their characterization by NMR spectro- scopy.…”

“…In contrast, the catalytic system 1/AlMe 3 /ETA was inert towards polymerization of olefins. [17] In this work, we have undertaken the EPR spectroscopic study of the vanadium(IV) species formed upon interaction of 1 with AlR 3 and AlR 2 Cl (R ¼ Me, Et) in the presence and absence of ETA. We have chosen complex 1 with bulky substituents in the phenolic and anilinic rings for our study, since vanadium phenoxyimine catalysts with less bulky substituents (e.g., vanadyl complex with N-(3,5-ditert-butylsalicylidene)anilinato ligands) exhibited EPR spectra with unresolved hyperfine structure from vanadium.…”