A second transition state for chain transfer to monomer in olefin polymerization promoted by group 4 metal catalysts

Journal of the American Chemical Society

Volumn 128, Issue 14, 2006, Pages 4524-4525

  Talarico, Giovanni ^a   Budzelaar, Peter H M ^b  

^a UNIVERSITY OF NAPLES FEDERICO II   (Italy)

^b UNIVERSITY OF MANITOBA   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

ALKENE; HAFNIUM; HYDROGEN; METAL; POLYMER; PROPYLENE; TITANIUM; ZIRCONIUM;

ARTICLE; CATALYSIS; CATALYST; CHEMICAL INTERACTION; CHEMICAL STRUCTURE; ENERGY TRANSFER; PHASE TRANSITION; POLYMERIZATION; PROTON TRANSPORT;

EID: 33646032123     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja0586034     Document Type: Article

References (20)

1. See, for example: Resconi, L.; Cavallo, L.; Fait, A.; Piemontesi, F. Chem. Rev. 2000, 100, 1253 and references therein.
2. 1
3. Margl, P.; Deng, L.; Ziegler, T. J. Am. Chem. Soc. 1999, 121, 154.
4. Cavallo, L.; Guerra, G. Macromolecules 1996, 29, 2729.
5. Stehling, U.; Diebold, J.; Kirsten, R.; Röll, W.; Brintzinger, H. H.; Jüngling, S.; Mülhaupt, R.; Langhauser, F. Organometallics 1994, 13, 964.
6. Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100, 1169.
7. Busico, V.; Cipullo, R.; Friederichs, N.; Ronca, S.; Talarico, G.; Togrou, M.; Wang, B. Macromolecules 2004, 37, 8201.
8. Talarico, G.; Busico, V.; Cavallo, L. Organometallics 2004, 23, 5989.
9. Tshuva, E. Y.; Goldberg, I.; Kol, M. J. Am. Chem. Soc. 2000, 122, 10706.
10. Leading references: (a) Makio, H.; Kashiwa, N.; Fujita, T. Adv. Synth. Catal. 2002, 344, 477.
11. (b) Coates, G. W.; Hustad, P. D.; Reinartz, S. Angew. Chem., Int. Ed. 2002, 41, 2236.
12. See, for example: Budzelaar, P. H. M.; Talarico, G. In Group 13 Chemistry III: Industrial Applications; Roesky, H. W., Atwood, D. A., Eds.; Structure and Bonding; Springer-Verlag: Berlin, 2003; Vol. 105, and references therein.
13. Calculations carried out with Gaussian03, Gaussian98, and Tnrbomole programs. For further details, see the Supporting Information.
14. 2M systems: see the Supporting Information for energies.
15. For the 4-Zr and 5-Zr systems, no separate path C seems to exist; the energy increases monotonically on increasing the Zr-H separation from 2.8 to 3.6 Å.
16. 1 symmetric system (see: Jayaratne, K. C.; Sita, L. R. J. Am. Chem. Soc. 2000, 122, 958) shows two TSs for both paths A and C, differing in the monomer and chain positions. Values in Table I refer to the lowest-energy TSs.
17. A for the extremely crowded system 6-Ti, one of the amidinate nitrogens has dissociated from the metal. This disturbs the otherwise consistent trend in metal effect somewhat.
18. The second-order saddle points were located using a development version of our own external optimizer (see Supporting Information).
19. Recently, the possibility of a path C-like TS has even been suggested for β-methyl transfer to monomer: Yang, P.; Baird, M. C. Organometallics 2005, 24, 6013.
20. The stronger preference of Ti (compared to Zr) for path C might be due to steric factors. For Hf vs Zr, the explanation is probably more complicated (Budzelaar, P. H. M.; Talarico, G. Manuscript in preparation). In ref 3, Ziegler et al. calculated a weakening of the M-H bond (relative to the M-C bond) on going from lighter to heavier metals, which agrees with our Zr → Hf trend.