267901-91-7Relevant academic research and scientific papers
Dimerization and polymerization of ethylene catalyzed by nickel complexes bearing multidentate amino-functionalized indenyl ligands
Groux, Laurent F.,Zargarian, Davit,Simon, Leonardo C.,Soares, Jo?o B.P.
, p. 51 - 58 (2008/10/08)
The combination of the neutral compound (η3:η 0-Ind(CH2)2NMe2)Ni(PPh 3)Cl (1) and methylaluminoxane (MAO) produces catalysts for the dimerization and the polymerization of ethylene. On the other hand, activation of the cationic complex (η3:η1-Ind(CH 2)2NMe2)Ni(PPh3)][BPh4] (2) by MAO or trimethylaluminum leads to a system which dimerizes ethylene with high turnover frequencies (2 × 103 s-1), but does not promote its polymerization. The effects of parameters such as ethylene pressure, reaction temperature and time, solvent type, and the type and amount of activator used have been studied in order to optimize the conditions for the formation of polyethylene. In addition, a number of reactions have been studied by NMR and GC-MS analysis in an effort to identify the catalytically active species. The results of these studies point to the involvement of cationic species in the dimerization of ethylene, whereas, the active catalyst for the polymerization of ethylene appears to be a non-cationic species.
Preparation and characterization of nickel complexes with η-indenyl ligands bearing a pendant aminoalkyl chain
Groux, Laurent F.,Bélanger-Gariépy, Francine,Zargarian, Davit,Vollmerhaus, Rainer
, p. 1507 - 1513 (2008/10/08)
The aminoindenyl complexes {Ind(CH2)3,4N(t-Bu)H}Ni(PPh3)Cl (7, 8) and {Ind(CH2)2,3NMe2}Ni(PPh3)Cl (9, 10) have been prepared and characterized by spectroscopy and, in the case of 7 and 9, by X-ray structural studies. Although there is no interaction between the Ni center and the amine moiety of these complexes in the solid state, solution spectra point to a temperature-dependent, intramolecular N→Ni coordination in complex 9 and a more facile, intermolecular interaction in 10. Abstraction of Cl- from these complexes led to the formation of the cations [{η3:η0-Ind(CH2)3,4N(t-Bu)H}Ni (PPh3)2]+ and [{η3:η1-Ind(CH2) 2,3NMe2}Ni(PPh3)]+ (11, 12). The origin of the observed differences in the reactivities of these complexes is discussed in terms of the lengths of the tether and the nature of the N-substituents.
