Reductive decomposition of cationic half-titanocene(IV) complexes, precursors of the active species in syndiospecific styrene polymerization

Organometallics

Volumn 15, Issue 2, 1996, Pages 480-482

  Grassi, Alfonso ^a   Zambelli, Adolfo ^a   Laschi, Franco ^b  

^a UNIVERSITY OF SALERNO   (Italy)

^b UNIVERSITY OF SIENA   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000118989     PISSN: 02767333     EISSN: None     Source Type: Journal    
DOI: 10.1021/om950666f     Document Type: Article

References (36)

1. (a) Soga, K.; Park, J. R.; Shioni, Y. Polym. Commun. 1991, 32, 310.
2. (b) Canich, J. M.; Hlatky, G. G.; Turner, H. W. Int. Pat. Appl. WO 92 00,333; Chem. Abstr. 1992, 116, 174967z.
3. (a) Zambelli, A.; Ammendola, P.; Proto, A. Macromolecules 1989, 22, 2126.
4. (b) Oliva, L.; Longo, P.; Grassi, A.; Ammendola, P.; Pellecchia, C. Makromol. Chem., Rapid Commun. 1990, 11, 519.
5. (c) Ricci, G.; Porri, L. Macromolecules 1994, 27, 868.
6. (d) Ricci, G.; Porri, L.; Giarrusso, A. Macromol. Symp. 1995, 89, 383 and references therein.
7. (a) Ishihara, N.; Seimiya, T.; Kuramoto, M.; Uoi, M. Macromolecules 1986, 19, 2464.
8. (b) Ready, T. E.; Day, R. O.; Chien, J. C. W.; Rausch, M. D. Macromolecules 1993, 26, 5822.
9. (c) Flores, J. C.; Chien, J. C. W.; Rausch, M. D. Organometallics 1994, 13, 4140.
10. Pellecchia, C.; Longo, P.; Proto, A.; Zambelli, A. Makromol. Chem., Rapid Commun. 1992, 13, 265.
11. Kucht, H.; Kucht, A.; Chien, J. C. W.; Rauch, M. D. Appl. Organomet. Chem. 1994, 8, 393.
12. Zambelli, A.; Pellecchia, C.; Oliva, L.; Longo, P.; Grassi, A. Makromol. Chem. 1991, 192, 223.
13. (a) Pellecchia, C.; Proto, A.; Zambelli, A. Macromolecules 1992, 25, 4450.
14. (b) Zambelli, A.; Proto, A.; Longo, P.; Oliva, L. Macromol. Chem. Phys. 1994, 195, 2623.
15. (a) Longo, P.; Grassi, A.; Oliva, L. Makromol. Chem. 1990, 191, 2387. Pseudo random ethylene-styrene copolymers are copolymers containing at most 50 mol % of styrene and lacking regioregularly arranged styrene-styrene diads even when the styrene content approaches 50 mol % (for this definition see: Stevens, J. C.; Timmers, F. J.; Wilson, D. R.; Schmidt, G. F.; Nickias, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S. Eur. Pat. Appl. 416815, 1991 (to Dow Chemical Co.); Chem. Abstr. 1991, 115, 93163).
16. (a) Longo, P.; Grassi, A.; Oliva, L. Makromol. Chem. 1990, 191, 2387. Pseudo random ethylene-styrene copolymers are copolymers containing at most 50 mol % of styrene and lacking regioregularly arranged styrene-styrene diads even when the styrene content approaches 50 mol % (for this definition see: Stevens, J. C.; Timmers, F. J.; Wilson, D. R.; Schmidt, G. F.; Nickias, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S. Eur. Pat. Appl. 416815, 1991 (to Dow Chemical Co.); Chem. Abstr. 1991, 115, 93163).
17. (a) Bochmann, M.; Wilsons, L. M. J. Chem. Soc., Chem. Commun. 1986, 1610.
18. (b) Bochmann, M.; Jaggar, A. J.; Nicholls, J. C. Angew. Chem., Int. Ed. Engl. 1990, 29, 780.
19. (c) Bochmann, M.; Jaggar, A. J. J. Organomet. Chem. 1992, 424, C5.
20. In the presence of the title catalysts insertion of the monomer is secondary for styrene and mainly primary for 1-olefins.
21. (a) Bueschges, U.; Chien, J. C. W. J. Polym. Sci., Part A 1989, 27, 1525.
22. (b) Chien, J. C. W.; Salajka, Z.; Dong, S. Macromolecules 1992, 29, 3199.
23. Grassi, A.; Pellecchia, C.; Oliva, L.; Laschi, F. Macromol. Chem. Phys. 1995, 196, 1093.
24. X-Band electron spin resonance (ESR) spectra were recorded with an ER 200 D-SRC Bruker spectrometer operating at ν = 9.62 GHz using an HS Bruker rectangular cavity. The control of the operational frequency was obtained with a Hewlett-Packard X5-32 B wave meter, and the magnetic field was calibrated with a DPPH (diphenylpicrylhydrazyl) free radical as suitable field marker. The control of the temperature was obtained with a Bruker ER 4111 VT device (±1 K).
25. The ESR resonances observed downfield from g = 1.977 are probably due to Ti(III) alkoxides and/or other products arising from oxygen traces and impurities present in the ESR tube. The relative intensities of these resonances erratically depend on the samples, and they seem unrelated to the polymerization catalysis (e.g., see Figure Id). These resonances are observed in all the spectra reported in this communication and will not discussed any further.
26. •, on the basis of the number and sharpness of the spectral lines (see Figure Ib).
27. It is worth noting that the same equilibrium has been observed for the corresponding Ti(IV) complexes (see: Gillis, D. J.; Tudoret, M. J.; Baird, C. J. Am. Chem. Soc. 1993, 115, 2543).
28. ⊥) = 1.972(3) suggesting that a significant orbital contribution of the unpaired electron affects the present spectral features.
29. -5) M. In the ESR spectrum of the A system (see Figure 1a) the concentration of Ti(III) species has been evaluated as corresponding to 1% of the starting Ti. After the addition of p-chlorostyrene or styrene, the area of the ESR signal (see Figure 1d) at 〈g〉 = 1.972, corresponding to the supposed active species, is integrated for 50% of the starting Ti. In the ESR spectrum of toluene solutions of the same catalytic system with [Ti] = 0.001 M (this value approximately corresponds to the catalyst concentrations typically used in styrene and olefin polymerizations) the concentration of Ti(III) species was about 1% of the starting Ti. After the addition of styrene, the ESR resonance observed at 〈g〉 = 1.972 is integrated for about 10% of the starting Ti.
30. Dam, C.; Sartori, F.; Maldotti, A. Macromol. Chem. Phys. 1994, 195, 2818.
31. 5: Haselwander, T.; Beck, S.; Brintzinger, H. H. In Ziegler Catalysts; Fink, G., Mulhaupt, R., Brintzinger, H. H., Eds.; Springer-Verlag: Berlin, 1995; p 181. With M = Ti and Cp′ = indenyl see: Bochmann, M.; Lancaster, S. J. J. Organomet. Chem. 1992, 434, C1).
32. 5: Haselwander, T.; Beck, S.; Brintzinger, H. H. In Ziegler Catalysts; Fink, G., Mulhaupt, R., Brintzinger, H. H., Eds.; Springer-Verlag: Berlin, 1995; p 181. With M = Ti and Cp′ = indenyl see: Bochmann, M.; Lancaster, S. J. J. Organomet. Chem. 1992, 434, C1).
33. 13C-enriched titanium complex afforded an impure product which was used in the polymerization runs without further purification.
34. Ammendola, P.; Tancredi, T.; Zambelli, A. Macromolecules 1986, 19, 307. The chemical shift of the signal is referred to hexamethyldisiloxane, used as internal reference.
35. (a) Pellecchia, C.; Longo, P.; Grassi, A.; Ammendola, P.; Zambelli, A. Makromol. Chem., Rapid Commun. 1987, 8, 277.
36. (b) Pellecchia, C.; Pappalardo, D.; Oliva, L.; Zambelli, A. J. Am. Chem. Soc. 1995, 117, 6593.