Details

Autor(en) / Beteiligte

• Gil, Marcelo P.
• Santos, J.H.Z. dos
• Casagrande, O.L.
• T. Simplício, Lílian M.
• Rocha, Zênis N. da

Titel

Spectroscopic and voltametric studies in titanium tris(pyrazolyl)borate catalysts

Ist Teil von

• Journal of molecular catalysis. A, Chemical, 2005-09, Vol.238 (1), p.96-101

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2005

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The ethylene polymerization using Tp Ms*TiCl 3 ( 1) (Tp Ms* = HB(3-mesitylpyrazolyl) 2(5-mesitylpyrazolyl) −) and Tp MsTiCl 3 ( 2) (Tp Ms = HB(3-mesityl-pyrazolyl) 3 −) was performed in toluene or hexane at 60 °C in the presence of MAO or TiBA/MAO (1:1) as cocatalysts. Higher activities were found for the polymerization reactions carried out in hexane, and using a combination of TiBA/MAO as cocatalysts. Absorciometric measurements in the UV–vis region and cyclic voltammetric have shown that such complexes when activated by MAO were not stable. Measurements carried out in the presence 1-hexene have demonstrated the necessity to add the cocatalyst in the presence of an olefin, i.e., ethylene or hexene-1 in order to stabilize the active species. Furthermore, these studies have revealed that after the activation process most of Ti remains as Ti IV.