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Synthesis and characterization of novel organotitanium compounds: Evaluation as olefin polymerization catalysts
Abstract
The reaction of TiCl$\sb3$(THF)$\sb3$ with one equivalent of isopropyltetramethylcyclopentadienyllithium (7) in THF followed by oxidation with HCl afforded ($\eta\sp5$-(CH$\sb3$)$\sb2$CHC$\sb5$(CH$\sb3$)$\sb4$) TiCl$\sb3$ (8) in 66% yield. Treatment of 8 with C$\sb5$H$\sb5$Tl in refluxing benzene gave ($\eta\sp5$-(CH$\sb{\rm 3}$)$\sb2$CHC$\sb5$(CH$\sb3$)$\sb4$) ($\eta\sp5$-C$\sb5$H$\sb5$)TiCl$\sb2$ (9) in 95% yield. Reaction of TiCl$\sb3$(THF)$\sb3$ with two equivalents of 7 in THF followed by oxidation with HCl afforded ($\eta\sp5$-(CH$\sb3$)$\sb2$CHC$\sb5$(CH$\sb3$)$\sb4$) $\sb2$TiCl$\sb2$ (10) in 73% yield. Compound 10 was characterized by a single-crystal X-ray diffraction study. Ethylene polymerizations by 9/MAO (MAO = methylalumoxane), 10/MAO and Cp$\sb2$TiCl$\sb2$/MAO are compared at 1.3 atm. over the temperature range of 0-50$\sp\circ$C. Ethylene polymerizations by Cp$\sb2$ZrCl$\sb2$/MAO and Cp$\sb2$HfCl$\sb2$/MAO catalysts were compared. The Hf catalysts have about two-thirds the activity of the Zr catalysts. This difference may be attributed to the greater number of active centers present in the Zr catalyst. The Hf catalyst shows a smaller dependence of: (1) polymer molecular 45 reacts with CpTl to produce ($\eta\sp5$-1-vinyl-2,3,4,5-tetramethylcyclopentadienyl)($\eta \sp5$-cyclopentadienyl)titanium dichloride (46) in high yield. Reduction of CpTiCl$\sb3$ in THF by magnesium in the presence of ether excess trimethylphosphine or 2,6-dimethylphenylisonitrile at ca. $-$30$\sp\circ$C produces the titanium (III) complexes CpTiCl$\sb2$(PMe$\sb3$)$\sb2$ (51) and CpTiCl$\sb2$(CNC$\sb6$H$\sb3$(CH$\sb3$)$\sb2$) $\sb2$ (52), respectively, in good yields. The X-ray structure of 51 is reported. Reduction of Cp*TiCl$\sb3$ in THF by magnesium produces Cp*$\sb2$TiCl$\sb2$MgCl$\sb2$TiClCp* (53). A reaction of pentabenzylcyclopentadienyllithium with TiCl$\sb3$(THF)$\sb3$, followed by treatment with HCl gas produces ($\eta\sp5$-C$\sb5$Bz$\sb5$)TiCl$\sb3$ (54). An isomer of pentabenzylcyclopentadiene was characterized by 2d $\sp1$H $\times$ $\sp1$H NMR and $\sp{13}$C NMR methods and spectra were fully assigned.
Subject Area
Inorganic chemistry|Polymer chemistry|Chemistry
Recommended Citation
Mallin, Daniel Todd, "Synthesis and characterization of novel organotitanium compounds: Evaluation as olefin polymerization catalysts" (1991). Doctoral Dissertations Available from Proquest. AAI9207430.
https://scholarworks.umass.edu/dissertations/AAI9207430