The dynamics of the β-agostic isopropyl complex (ArN=C(R)-C(R)=NAr)Pd(CH(CH2-μ-H)(CH3)) +BAr4′- (Ar = 2,6-C6H3(i-Pr)2): Evidence for in-place rotation versus dissociation of the agostic methyl group

Organometallics

Volumn 17, Issue 11, 1998, Pages 2290-2296

  Tempel, Daniel J ^a   Brookhart, Maurice ^a  

^a The University of North Carolina at Chapel Hill   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001673737     PISSN: 02767333     EISSN: None     Source Type: Journal    
DOI: 10.1021/om971137+     Document Type: Article

References (37)

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10. For an earlier investigation of the dynamics of this system, see: (a) Byrne, J. W.; Kress, J. R. M.; Osborn, J.; Ricard, L.; Weiss, R. E. J. Chem. Soc., Chem. Commun. 1977, 662-663. (b) Byrne, J. W.; Blaser, H. U.; Osborn, J. A. J. Am. Chem. Soc. 1975, 97, 3871-3873.
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15. +, see: (a) Spencer, J. L.; Mhinzi, G. S. J. Chem. Soc., Dalton Trans. 1995, 23, 3819-3824. (b) Carr, N.; Mole, L.; Orpen, A. G.; Spencer, J. L. J. Chem. Soc., Dalton Trans. 1992, 18, 2653-2662. (c) Mole, L.; Spencer, J. L.; Carr, N.; Orpen, A. G. Organometallics 1991, 10, 49-52. (d) Conroy-Lewis, F. M.; Mole, L.; Redhouse, A. D.; Litster, S. A.; Spencer, J. L. J. Chem. Soc., Chem. Commun. 1991, 22, 1601-1603.
16. +, see: (a) Spencer, J. L.; Mhinzi, G. S. J. Chem. Soc., Dalton Trans. 1995, 23, 3819-3824. (b) Carr, N.; Mole, L.; Orpen, A. G.; Spencer, J. L. J. Chem. Soc., Dalton Trans. 1992, 18, 2653-2662. (c) Mole, L.; Spencer, J. L.; Carr, N.; Orpen, A. G. Organometallics 1991, 10, 49-52. (d) Conroy-Lewis, F. M.; Mole, L.; Redhouse, A. D.; Litster, S. A.; Spencer, J. L. J. Chem. Soc., Chem. Commun. 1991, 22, 1601-1603.
17. +, see: (a) Spencer, J. L.; Mhinzi, G. S. J. Chem. Soc., Dalton Trans. 1995, 23, 3819-3824. (b) Carr, N.; Mole, L.; Orpen, A. G.; Spencer, J. L. J. Chem. Soc., Dalton Trans. 1992, 18, 2653-2662. (c) Mole, L.; Spencer, J. L.; Carr, N.; Orpen, A. G. Organometallics 1991, 10, 49-52. (d) Conroy-Lewis, F. M.; Mole, L.; Redhouse, A. D.; Litster, S. A.; Spencer, J. L. J. Chem. Soc., Chem. Commun. 1991, 22, 1601-1603.
18. +, see: (a) Spencer, J. L.; Mhinzi, G. S. J. Chem. Soc., Dalton Trans. 1995, 23, 3819-3824. (b) Carr, N.; Mole, L.; Orpen, A. G.; Spencer, J. L. J. Chem. Soc., Dalton Trans. 1992, 18, 2653-2662. (c) Mole, L.; Spencer, J. L.; Carr, N.; Orpen, A. G. Organometallics 1991, 10, 49-52. (d) Conroy-Lewis, F. M.; Mole, L.; Redhouse, A. D.; Litster, S. A.; Spencer, J. L. J. Chem. Soc., Chem. Commun. 1991, 22, 1601-1603.
19. Details of this isomerization will be discussed in a future publication. Theoretical studies predict the β-agostic isopropyl complex to be more stable than the n-propyl agostic complex, see: (a) Musaev, D. G.; Svensson, M.; Morokuma, K.; Strömberg, S.; Zetterberg, K.; Seigbahn, P. E. M. Organometallics 1997, 16, 1933-1945. (b) Musaev, D. G.; Froese, R. D. J.; Svensson, M.; Morokuma, K. J. Am. Chem. Soc. 1997, 119, 363-374. (c) Deng, L. Q.; Margl, P.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 1094-1100. (d) Deng, L. Q.; Woo, T. K.; Cavallo, L.; Margl, P. M.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 6177-6186.
20. Details of this isomerization will be discussed in a future publication. Theoretical studies predict the β-agostic isopropyl complex to be more stable than the n-propyl agostic complex, see: (a) Musaev, D. G.; Svensson, M.; Morokuma, K.; Strömberg, S.; Zetterberg, K.; Seigbahn, P. E. M. Organometallics 1997, 16, 1933-1945. (b) Musaev, D. G.; Froese, R. D. J.; Svensson, M.; Morokuma, K. J. Am. Chem. Soc. 1997, 119, 363-374. (c) Deng, L. Q.; Margl, P.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 1094-1100. (d) Deng, L. Q.; Woo, T. K.; Cavallo, L.; Margl, P. M.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 6177-6186.
21. Details of this isomerization will be discussed in a future publication. Theoretical studies predict the β-agostic isopropyl complex to be more stable than the n-propyl agostic complex, see: (a) Musaev, D. G.; Svensson, M.; Morokuma, K.; Strömberg, S.; Zetterberg, K.; Seigbahn, P. E. M. Organometallics 1997, 16, 1933-1945. (b) Musaev, D. G.; Froese, R. D. J.; Svensson, M.; Morokuma, K. J. Am. Chem. Soc. 1997, 119, 363-374. (c) Deng, L. Q.; Margl, P.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 1094-1100. (d) Deng, L. Q.; Woo, T. K.; Cavallo, L.; Margl, P. M.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 6177-6186.
22. Details of this isomerization will be discussed in a future publication. Theoretical studies predict the β-agostic isopropyl complex to be more stable than the n-propyl agostic complex, see: (a) Musaev, D. G.; Svensson, M.; Morokuma, K.; Strömberg, S.; Zetterberg, K.; Seigbahn, P. E. M. Organometallics 1997, 16, 1933-1945. (b) Musaev, D. G.; Froese, R. D. J.; Svensson, M.; Morokuma, K. J. Am. Chem. Soc. 1997, 119, 363-374. (c) Deng, L. Q.; Margl, P.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 1094-1100. (d) Deng, L. Q.; Woo, T. K.; Cavallo, L.; Margl, P. M.; Ziegler, T. J. Am. Chem. Soc. 1997, 119, 6177-6186.
23. 13C-labeled material (6*, see below).
24. Integration of this broad band is not sufficiently accurate to rule out a 7H band due to averaging of all seven hydrogens of the isopropyl group.
25. 1H line shapes suggests these processes occur at similar rates, we prefer the simplest explanation which ascribes the isopropyl group dynamics to the front-to-back process shown in Scheme 3. However, we cannot rule out some contribution to the isopropyl averaging process through an olefin hydride intermediate.
26. Budzelaar, P. H. M. gNMR for Macintosh, Version 3.6.5; Cherwell Scientific Publishing Limited: Oxford, 1992-1996.
27. Temperatures below -95 °C were extrapolated.
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30. 3Br can result in explosions. Extreme precautions are required.)
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37. Prepared by Lynda K. Johnson according to literature procedure: Andersen, R. A.; Wilkinson, G. Inorg. Synth. 1979, 19, 262-265.