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New organometallic derivatives of titanium and zirconium with application in polymerization catalysis of olefins
Abstract
A variety of new chiral one-carbon-bridged metallocene derivatives of titanium and zirconium have been prepared. Addition of the anions of cyclopentadiene, indene and fluorene to 6-t-butylfulvene and 6,6-dimethylfulvene produced the ligands t-BuCH(C$\sb5$H$\sb5$)R (R = C$\sb5$H$\sb5$, 22; C$\sb9$H$\sb7$, 23; C$\sb{13}$H$\sb9$, 26) and (CH$\sb3$)$\sb2$C(C$\sb5$H$\sb5$)R (R = C$\sb9$H$\sb7$, 24; 3-CH$\sb3$-C$\sb9$H$\sb6$, 25). The reaction of the ligands 22-26 with n-BuLi produced the corresponding bis-anions, which were reacted with titanium or zirconium tetrachloride at low temperature ($-$78$\sp\circ$C), to produce the complexes t-BuCH($\eta\sp5$-C$\sb5$H$\sb4$)(R)MCl$\sb2$ (R = $\eta\sp5$-C$\sb5$H$\sb4$, M = Ti, 27; R = $\eta\sp5$-C$\sb5$H$\sb4$, M = Zr, 29; R = $\eta\sp5$-C$\sb9$H$\sb6$, M = Ti, 30; R = $\eta\sp5$-C$\sb9$H$\sb6$, M = Zr, 31; R = $\eta\sp5$-C$\sb{13}$H$\sb8$, M = Zr, 32) and (CH$\sb3$)$\sb2$C($\eta\sp5$-C$\sb5$H$\sb4$)(R)MCl$\sb2$ (R = $\eta\sp5$-C$\sb9$H$\sb6$, M = Ti, 34; R = $\eta\sp5$-C$\sb9$H$\sb6$, M = Zr, 14; R = 3-CH$\sb3$-$\eta\sp5$-C$\sb9$H$\sb5$, M = Ti, 35; R = 3-CH$\sb3$-$\eta\sp5$-C$\sb9$H$\sb5$, M = Zr, 36). The structure of 34 is very rigid due to strain at the bridgehead carbon. The chlorine atoms in complexes 27 and 32 can be easily replaced by methyl groups. By treatment of 27 and 32 with MeLi in diethyl ether the corresponding dimethyl derivatives 28 and 33 were obtained. The influence of the symmetry of the bridge in metallocene Ziegler-Natta catalysis was tested. The chiral complex 32 was compared to the symmetric system $\rm (CH\sb3)\sb2C(\eta\sp5$-$\rm C\sb5H\sb4)(\eta\sp5$-$\rm C\sb{13}H\sb8)ZrCl\sb2({\bf 52})$ in the syndiospecific polymerization of propylene. The polymerization behavior of precursors 32 and 52 were very similar. The substituents on the bridgehead carbon had little or no influence on the polymerization process because of their remote location from the available coordination sites involved in the polymerization reaction. The symmetry of the cyclopentadienyl groups was also tested for the polymerization of propylene with metallocene systems. Precursors 14 and 36 polymerized propylene to low molecular weight materials in reduced activities compared to the symmetric precursor 52. The polymers obtained with 14 and 36 present a structure assigned to hemiisotactic chains. New sulfur and selenium derivatives of the mixed sandwich complex ($\eta\sp5$-$\rm C\sb5H\sb5)(\eta\sp7$-$\rm C\sb7H\sb7)Ti\ ({\bf 63})$ were prepared. Complexes ($\eta\sp5$-$\rm C\sb5H\sb5)(\eta\sp7$-$\rm C\sb7H\sb6$R)Ti (R = SCH$\sb3$, 82; SPh, 84; SePh, 86), ($\eta\sp5$-$\rm C\sb5H\sb4R)(\eta\sp7$-$\rm C\sb7H\sb7$)Ti (R = SCH$\sb3$, 81) and ($\eta\sp5$-$\rm C\sb5H\sb4R)(\eta\sp7$-$\rm C\sb7H\sb6$R)Ti (R = SCH$\sb3$, 80; SPh, 83; SePh, 85) were prepared by reaction of the mono- or dilithio-derivatives of 63 with one or two equivalents of the corresponding dichalcogenide. Compound 80 behaved as a bidentated ligand. Heterobimetallic derivatives 88-90 were obtained by treatment of 80 with Cr(CO)$\sb4$(nbd), Cr(CO)$\sb4$(nbd) and PtCl$\sb2$(PhCN)$\sb2$, respectively.
Subject Area
Organic chemistry|Polymer chemistry|Inorganic chemistry|Chemistry
Recommended Citation
Fierro, Ricardo, "New organometallic derivatives of titanium and zirconium with application in polymerization catalysis of olefins" (1993). Doctoral Dissertations Available from Proquest. AAI9408272.
https://scholarworks.umass.edu/dissertations/AAI9408272