摘要:
                                Reactions of the vanadyl polyphenolate complexes {VO[p-tert-butylcalix[4]arene(O)(3)(OMe)]) (1) and [VO(OArCH2Ar'CH2OAr)](2) (Ar = 4,6-tert-butylphenol; Ar' = 4-tert-butylphenol) (2) with AlR3 and AlR2Cl, in the absence and in the presence of reactivator (ethyltrichloroacetate, ETA), were monitored by EPR (R = Me, Et). It was shown, that vanadium(IV) complexes with proposed structures (LtVR)-R-IV(AlR3) and (LIVR)-R-IV(AlR2Cl) are formed upon interaction of 1 with AlR3 and AlR2Cl, respectively (20 degrees C, L-1 is the initial oxo-calix[4]arene ligand). Similarly, vanadium(IV) complexes with proposed structures (L2VR)-R-IV(AlR3) and (L2VR)-R-IV(AlR2Cl) are formed upon interaction or 2 with AlR3 and AlR2Cl (L-2 is the initial ligand of 2). The growth of the concentration of (L1VR)-R-IV(AlR2Cl) and (L2VR)-R-IV(AlR2Cl) correlates with the increase of the ethylene polymerization activity of the catalyst systems 1,2/AlR2Cl/ETA. It is proposed therefore that vanadium(IV) species of the type (L1VR)-R-IV(AlR2Cl) and (L2VR)-R-IV(AlR2Cl) can be the active species (or their immediate precursors) of the catalyst system 1,2/AlR2Cl/ETA.