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Volumn 119, Issue 26, 1997, Pages 6177-6186

The role of bulky substituents in Brookhart-type Ni(II) diimine catalyzed olefin polymerization: A combined density functional theory and molecular mechanics study

Author keywords

[No Author keywords available]

Indexed keywords

CATALYSIS; ETHYLENE; MATHEMATICAL MODELS; NICKEL; QUANTUM THEORY; STABILIZATION;

EID: 0031549124     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja970226a     Document Type: Article
Times cited : (361)

References (57)
  • 9
    • 0038609505 scopus 로고
    • These systems have been calculated theoretically by Fan and Ziegler: (a) Fan, L.; Krzywicki, A.; Somogyvari, A.; Ziegler, T. Inorg. Chem. 1994, 33, 5287. (b) Fan, L.; Krzywicki, A.; Somogyvari, A.; Ziegler, T. Inorg. Chem. 1996, 25, 4003.
    • (1994) Inorg. Chem. , vol.33 , pp. 5287
    • Fan, L.1    Krzywicki, A.2    Somogyvari, A.3    Ziegler, T.4
  • 10
    • 0001079509 scopus 로고    scopus 로고
    • These systems have been calculated theoretically by Fan and Ziegler: (a) Fan, L.; Krzywicki, A.; Somogyvari, A.; Ziegler, T. Inorg. Chem. 1994, 33, 5287. (b) Fan, L.; Krzywicki, A.; Somogyvari, A.; Ziegler, T. Inorg. Chem. 1996, 25, 4003.
    • (1996) Inorg. Chem. , vol.25 , pp. 4003
    • Fan, L.1    Krzywicki, A.2    Somogyvari, A.3    Ziegler, T.4
  • 18
    • 0004124784 scopus 로고
    • te Riele, H. J. J., Dekker, T. J., van de Horst, H. A., Eds.; Elsevier: Amsterdam, The Netherlands
    • Ravenek, W. Algorithms and Applications on Vector and Parallel Computers; te Riele, H. J. J., Dekker, T. J., van de Horst, H. A., Eds.; Elsevier: Amsterdam, The Netherlands, 1987.
    • (1987) Algorithms and Applications on Vector and Parallel Computers
    • Ravenek, W.1
  • 23
    • 0003990093 scopus 로고
    • Department of Theoretical Chemistry, Free University: Amsterdam, The Netherlands
    • Krijn, J.; Baerends, E. J. Fit Functions in the HFS Method; Department of Theoretical Chemistry, Free University: Amsterdam, The Netherlands, 1984.
    • (1984) Fit Functions in the HFS Method
    • Krijn, J.1    Baerends, E.J.2
  • 30
    • 16944364936 scopus 로고    scopus 로고
    • Woo, T. K.; Cavallo, L.; Ziegler, T. Unpublished work
    • Woo, T. K.; Cavallo, L.; Ziegler, T. Unpublished work.
  • 42
    • 16944362978 scopus 로고    scopus 로고
    • note
    • The reported values are the angle between the normal vectors of the two planes defined by the Ni, N, C atoms of the Ni - diimine ring and C1, C2, C6 atoms of the aryl ring.
  • 43
    • 16944365458 scopus 로고    scopus 로고
    • note
    • Two linear transit calculations were performed in which one of the Ni-C(ethylene) distances was used as the reaction coordinate. The reverse process, from the resting state to the free Ni alkyl cation and free ethylene unit, was examined.
  • 44
    • 16944363411 scopus 로고    scopus 로고
    • Woo, T. K.; Margl, P. M.; Deng, L.; Blöchl, P. E.; Ziegler, T. Work in progress
    • Woo, T. K.; Margl, P. M.; Deng, L.; Blöchl, P. E.; Ziegler, T. Work in progress.
  • 47
    • 16944365079 scopus 로고    scopus 로고
    • note
    • We have also examined the first insertion or chain initialization process with our pure QM/MM model. The first insertion of ethylene into the Ni - methyl bond is calculated to proceed through a barrier of 5.7 kcal/mol. This is significantly diminished from the pure QM model, which gives a first insertion barrier of 11.1 kcal/mol.
  • 48
    • 16944366869 scopus 로고    scopus 로고
    • note
    • The QM/MM structures 3 and 4 correspond to the pure QM structures 7a and 8a of ref 10.
  • 49
    • 16944364810 scopus 로고    scopus 로고
    • Professor Maurice Brookhart (Department of Chemistry, University of North Carolina at Chapel Hill). A private communication.
    • Professor Maurice Brookhart (Department of Chemistry, University of North Carolina at Chapel Hill). A private communication.
  • 50
    • 16944361957 scopus 로고    scopus 로고
    • note
    • This is further corroborated by the experimental observation that increased ethylene pressures decrease the branching, while not dramatically affecting the polymer yields or molecular weights.
  • 57
    • 16944365819 scopus 로고    scopus 로고
    • note
    • Comparison of the combined QM/MM and the stepwise QM then MM methodologies can be found in ref 40.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.