A vanadium(V) complex with a tetradentate [OSSO]-type bis(phenolato) ligand: Synthesis, structure, and ethylene polymerization activity

Synthesis and olefin homo- and copolymerization behavior of new vanadium complexes bearing [OSSO]-type ligands

“…Their activities were very high, over 40,000 kg/(mol h). Besides, the activities of the studied vanadium complexes are much higher than those observed in ethylene polymerization for titanium, hafnium and zirconium complexes which contain [OSSO] ligands of different structure [12,19], and for the vanadium(V) complex which contains a trans-1,2-dithiacyclohexane-bridged bis(phenolato) ligand activated with MAO [20]. After the complex amount was reduced to 0.05 lmol, the activity of the catalysts was lowered, which may result from easier reduction of vanadium to inactive oxidation states at a very high Al:V molar ratio amounting to 60,000:1, with a higher loss of activity observed for the complex 2V.…”

“…In contrast to group 4 elements, the group 5 complexes bearing [OSSO]-type bis(phenolate) ligands are rare [20,21]. The oxovanadium(V) complex in conjunction with MAO showed high activity in ethylene polymerization but did not catalyze the propylene and styrene polymerization [20], and the tantalum(V) complex activated with Al(iBu) 3 /Ph 3 CB(C 6 F 5 ) 4 gave isotactic poly(1-hexene) with narrow dispersity [21].…”

Metal Complexes Bearing Sulfur-Containing Ligands as Catalysts in the Reaction of CO2 with Epoxides

“…On this basis, it was thought that the introduction in the ligand of a soft donor, such as sulfur, can be advantageous because of the possibility to tune the Lewis acidity of the metal center by using the weaker metal-donor interaction. Indeed, many successful examples of catalysts having sulfur-containing ligands have been reported to date in the field of olefin polymerization [39][40][41][42][43][44][45][46], ring-opening polymerization of cyclic esters [47][48][49], hydroamination [50] and hydrosilylation [51] with various metal centers ( Figure 4). In this context, theoretical and experimental studies have shown the crucial role of the hemilabile sulfur atom in determining the catalytic activity and selectivity [52,53].…”

Vanadium, niobium and tantalum

“…89 The tetradentate ligand, trans-1,2-dithiacyclohexanediyl-2,2 0bis(6-tert-butyl-4-methylphenol) was treated to [VOCl 3 ] to form [LVOCl]. 90 This complex was shown to be an active catalyst in ethylene polymerisation. Vanadium complexes bearing sulfur and ethylidene-bridged diphenol were synthesised and were found to be active catalysts and procatalysts for ethylene polymerisation as well as the polymerisation of e-caprolactone.…”