219947-47-4Relevant academic research and scientific papers
Alkyl complexes of group 4 metals containing a tridentate-linked amido-cyclopentadienyl ligand: Synthesis, structure, and reactivity including ethylene polymerization catalysis
Amor, Francisco,Butt, Angelika,Du Plooy, Karen E.,Spaniol, Thomas P.,Okuda, Jun
, p. 5836 - 5849 (1998)
A series of group 4 metal complexes M(η5:η1: η1-C5Me4SiMe2NCH 2CH2X)R2 (M = Ti; R = Me, CH2Ph; M = Zr, Hf; R = Me, Et, nPr, nBu, CH2Ph, CH 2SiMe3, Ph) containing the tridentate-linked amido - tetramethylcyclopentadienyl ligand C5Me4SiMe 2NCH2CH2X (X = OMe, NMe2) were synthesized by alkylation of the dichloro complexes M(η5: η1:η1-C5Me4-SiMe 2NCH2CH2X)Cl2. The complexes were characterized by 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. Nuclear Overhauser effect measurements of the dimethyl complexes show that, in solution, the side chains of the zirconium derivatives coordinate intramolecularly, in contrast to the titanium complexes. The crystal structures of the zirconium alkyls Zr(η5: η1η1-C5Me4SiMe 2NCH2CH2OMe)R2 (R = Me, Ph) were determined by X-ray diffraction studies. Both complexes adopt a trigonal-bipyramidal structure, with the five-membered ring and the methoxy group in the apical positions. Insertion of carbon monoxide into the hafnium dimethyl and di(n-butyl) complexes led to the η2-acyl derivatives Hf(η5:η1:η1-C5Me 4SiMe2NCH2CH2OMe)(η2- COR)R (R = Me, nBu). Chloro mono(ethyl) complexes underwent insertion of fert-butyl isonitrile to give η2-iminoacyl derivatives M(η5:η1-C5Me4SiMe 2NCH2CH2X){η2-C(=N tBu)Et}Cl. The X-ray diffraction structure of the titanium complex Ti(η5:η1-C5Me4SMe 2NCH2CH2OMe){η2C(=N tBu)Et}Cl showed a square-pyramidal configuration with the imino nitrogen trans to the amido nitrogen. The zirconium dimethyl complexes Zr(η5:η1:η1-C5Me 4SiMe2NCH2CH2X)Me2 reacted with B(C6F5)3 to form the contact ion pairs [Zr(η5:η1:η1-C 5Me4SiMe2NCH2CH2X)Me] +[MeB(C6F5)3]-. Reaction between the titanium dibenzyl Ti(η5:η1-C 5Me4SiMe2NCH2CH2X) (CH2Ph)2 and B(C6F5)3 resulted in the clean formation of the solvent-separated ion pair [Ti(η5:η1:η1-C5Me 4SiMe2-NCH2CH2X)(CH 2Ph)]+[(PhCH2)B(C6F 5)3]-. When activated with methylaluminoxane, the complexes Ti(η5:η1-C5Me 4SiMe2NCH2CH2OMe)Cl2 and M(η5:η1:η1-C5Me 4SiMe2NCH2CH2- OMe)R2 (M = Zr, Hf; R = Me, nBu) are active in the polymerization of ethylene.
