Why are methylenecyclopropane and 1-methylcylopropene more 'strained' than methylcyclopropane?

Journal of the American Chemical Society

Volumn 119, Issue 25, 1997, Pages 5930-5933

  Johnson, William T G ^a   Borden, Weston Thatcher ^a  

^a UNIVERSITY OF WASHINGTON   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

1 METHYLCYCLOPROPENE; METHYLCYCLOPROPANE; METHYLENECYCLOPROPANE; UNCLASSIFIED DRUG;

ARTICLE; BINDING AFFINITY; BINDING KINETICS; CHEMICAL BINDING; HYDROGEN BOND; MATHEMATICAL ANALYSIS; MATHEMATICAL COMPUTING; THERMODYNAMICS;

EID: 0030741437     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9638061     Document Type: Article

References (36)

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5. See, for example: Liebman, J. F.; Greenberg, A. Chem. Rev. 1976, 76, 311, 324. Greenberg, A.; Liebman, J. F. Strained Organic Molecules; Academic Press: New York, 1978; pp 91-3. Haiton, B.; Banwell, M. G. In The Chemistry of the Cyclopropyl Group; Rappoport, Z., Ed.; John Wiley & Sons: New York, 1987; Part 2, Chapter 21, p 1251.
6. See, for example: Liebman, J. F.; Greenberg, A. Chem. Rev. 1976, 76, 311, 324. Greenberg, A.; Liebman, J. F. Strained Organic Molecules; Academic Press: New York, 1978; pp 91-3. Haiton, B.; Banwell, M. G. In The Chemistry of the Cyclopropyl Group; Rappoport, Z., Ed.; John Wiley & Sons: New York, 1987; Part 2, Chapter 21, p 1251.
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9. For examples see: Sun, H.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1987, 109, 5275. Hrovat, D. A.; Sun, H.; Borden, W. T. THEOCHEM 1988, 163, 51. Wang, S. Y.; Borden, W. T. J. Am. Chem. Soc. 1989, 111, 7282. Hammons, J. H.; Coolidge, M. B.; Borden, W. T. J. Phys. Chem. 1990, 94, 5468. Coolidge, M. B.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 2354. Nicolaides, A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 8682.
10. For examples see: Sun, H.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1987, 109, 5275. Hrovat, D. A.; Sun, H.; Borden, W. T. THEOCHEM 1988, 163, 51. Wang, S. Y.; Borden, W. T. J. Am. Chem. Soc. 1989, 111, 7282. Hammons, J. H.; Coolidge, M. B.; Borden, W. T. J. Phys. Chem. 1990, 94, 5468. Coolidge, M. B.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 2354. Nicolaides, A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 8682.
11. For examples see: Sun, H.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1987, 109, 5275. Hrovat, D. A.; Sun, H.; Borden, W. T. THEOCHEM 1988, 163, 51. Wang, S. Y.; Borden, W. T. J. Am. Chem. Soc. 1989, 111, 7282. Hammons, J. H.; Coolidge, M. B.; Borden, W. T. J. Phys. Chem. 1990, 94, 5468. Coolidge, M. B.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 2354. Nicolaides, A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 8682.
12. For examples see: Sun, H.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1987, 109, 5275. Hrovat, D. A.; Sun, H.; Borden, W. T. THEOCHEM 1988, 163, 51. Wang, S. Y.; Borden, W. T. J. Am. Chem. Soc. 1989, 111, 7282. Hammons, J. H.; Coolidge, M. B.; Borden, W. T. J. Phys. Chem. 1990, 94, 5468. Coolidge, M. B.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 2354. Nicolaides, A.; Borden, W. T. J. Am. Chem. Soc. 1992, 114, 8682.
13. Roth, W. R.; Quast, M. Unpublished results.
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15. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.; Johnson, B. G.; Robb, M. A.; Cheeseman, J. R.; Keith, T.; Petersson, G. A.; Montgomery, J. A.; Raghavachari, K.; Al-Laham, M. A.; Zakrzewski, V. G.; Ortiz, J. V.; Foresman, J. B.; Peng, C. Y.; Ayala, P. Y.; Chen, W.; Wong, M. W.; Andres, J. L.; Replogle, E. S.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Binkley, J. S.; Defrees, D. J.; Baker, J.; Stewart, J. P.; Head-Gordon, M.; Gonzalez, C.; Pople, J. A. Gaussian 94, Revision B.3; Gaussian, Inc.: Pittsburgh, PA, 1995.
16. Möller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. Pople, J. A.; Binkley, J. S.; Seeger, R. Int. J. Quantum Chem. 1976, 570, 1.
17. Möller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. Pople, J. A.; Binkley, J. S.; Seeger, R. Int. J. Quantum Chem. 1976, 570, 1.
18. Andersson, K.; Malmqvist, P.-Å.; Roos, B. O.; Sadlej, A. J.; Wolinski, K. J. Phys. Chem. 1990, 94, 5483. Andersson, K.; Malmqvist, P.-Å.; Roos, B. O. J. Chem. Phys. 1992, 96, 1218.
19. Andersson, K.; Malmqvist, P.-Å.; Roos, B. O.; Sadlej, A. J.; Wolinski, K. J. Phys. Chem. 1990, 94, 5483. Andersson, K.; Malmqvist, P.-Å.; Roos, B. O. J. Chem. Phys. 1992, 96, 1218.
20. Andersson, K.; Blomberg, M. R. A.; Fülscher, M. P.; Karlström, G.; Kellö, V.; Lindh, R.; Malmqvist, P.-Å.; Noga, J.; Olsen, J.; Roos, B. O.; Sadlej, A. J.; Siegbahn, P. E. M.; Urban, M.; Widmark, P.-O. MOLCAS-3; University of Lund: Sweden.
21. The amount by which (2,2)CASSCF overestimates the barrier to planarity at the tertiary radical center, relative to CASPT2N, is fortuitously nearly the same as the amount by which (2,2)CASSCF underestimates the stabilizing interaction between the primary radical center and the bent bonds of the cyclopropane ring. However, since CASPT2N uses second-order perturbation theory, it tends to overestimate the effects of dynamic correlation. Inclusion of these effects variationally would be expected to yield results that are bracketed by the CASSCF and CASPT2N values but which are closer to the latter.
22. Benson, S. W. J. Chem. Educ. 1965, 42, 502. Benson, S. W. Thermochemical Kinetics, 2nd ed.; Wiley: New York, 1976; pp 63-65.
23. Benson, S. W. J. Chem. Educ. 1965, 42, 502. Benson, S. W. Thermochemical Kinetics, 2nd ed.; Wiley: New York, 1976; pp 63-65.
24. After correcting for differences in zero-point energies and heat capacities, our calculations predict ΔH‡ = 3.3 kcal/mol for inversion in the 1-methylcyclopropyl radical at 298 K. This calculated value is in excellent agreement with the experimental value of Ea = 3.1 ±0.2 kcal/ mol, obtained by an EPR study of the rate of inversion of this radical in the temperature range 92-161 K. Deycard, S.; Hughes, L.; Lusztyk, J.; and Ingold, K. U. J. Am. Chem. Soc. 1987, 109, 4954.
25. For other ab initio calculations of barriers to inversion in cyclopropyl radicals see, inter alia: Apeloig, Y.; Nakash, M. J. Am. Chem. Soc. 1994, 116, 10781. Barone, V.; Minichino, C.; Faucher, H.; Subra, R.; Grand, A. Chem. Phys. Lett. 1993, 205, 324. Lien, M. H.; Hopkinson, A. C. J. Comput. Chem. 1985, 6, 274.
26. For other ab initio calculations of barriers to inversion in cyclopropyl radicals see, inter alia: Apeloig, Y.; Nakash, M. J. Am. Chem. Soc. 1994, 116, 10781. Barone, V.; Minichino, C.; Faucher, H.; Subra, R.; Grand, A. Chem. Phys. Lett. 1993, 205, 324. Lien, M. H.; Hopkinson, A. C. J. Comput. Chem. 1985, 6, 274.
27. For other ab initio calculations of barriers to inversion in cyclopropyl radicals see, inter alia: Apeloig, Y.; Nakash, M. J. Am. Chem. Soc. 1994, 116, 10781. Barone, V.; Minichino, C.; Faucher, H.; Subra, R.; Grand, A. Chem. Phys. Lett. 1993, 205, 324. Lien, M. H.; Hopkinson, A. C. J. Comput. Chem. 1985, 6, 274.
28. McMillen, D. F.; Golden, D. M.; Benson, S. W. Int. J. Chem. Kinet. 1971, 3, 359. Danen, W. C. J. Am. Chem. Soc. 1972, 94, 4835. Radom, L; Paviot, J.; Pople, J. A.; Schleyer, P. v. R. J. Chem. Soc., Chem. Commun. 1974, 58. Walton, J. C. Magn. Reson. Chem. 1987, 25, 998. Hehre, W. J., J. Am. Chem. Soc. 1973, 95, 2643.
29. McMillen, D. F.; Golden, D. M.; Benson, S. W. Int. J. Chem. Kinet. 1971, 3, 359. Danen, W. C. J. Am. Chem. Soc. 1972, 94, 4835. Radom, L; Paviot, J.; Pople, J. A.; Schleyer, P. v. R. J. Chem. Soc., Chem. Commun. 1974, 58. Walton, J. C. Magn. Reson. Chem. 1987, 25, 998. Hehre, W. J., J. Am. Chem. Soc. 1973, 95, 2643.
30. McMillen, D. F.; Golden, D. M.; Benson, S. W. Int. J. Chem. Kinet. 1971, 3, 359. Danen, W. C. J. Am. Chem. Soc. 1972, 94, 4835. Radom, L; Paviot, J.; Pople, J. A.; Schleyer, P. v. R. J. Chem. Soc., Chem. Commun. 1974, 58. Walton, J. C. Magn. Reson. Chem. 1987, 25, 998. Hehre, W. J., J. Am. Chem. Soc. 1973, 95, 2643.
31. McMillen, D. F.; Golden, D. M.; Benson, S. W. Int. J. Chem. Kinet. 1971, 3, 359. Danen, W. C. J. Am. Chem. Soc. 1972, 94, 4835. Radom, L; Paviot, J.; Pople, J. A.; Schleyer, P. v. R. J. Chem. Soc., Chem. Commun. 1974, 58. Walton, J. C. Magn. Reson. Chem. 1987, 25, 998. Hehre, W. J., J. Am. Chem. Soc. 1973, 95, 2643.
32. McMillen, D. F.; Golden, D. M.; Benson, S. W. Int. J. Chem. Kinet. 1971, 3, 359. Danen, W. C. J. Am. Chem. Soc. 1972, 94, 4835. Radom, L; Paviot, J.; Pople, J. A.; Schleyer, P. v. R. J. Chem. Soc., Chem. Commun. 1974, 58. Walton, J. C. Magn. Reson. Chem. 1987, 25, 998. Hehre, W. J., J. Am. Chem. Soc. 1973, 95, 2643.
33. The C - H BDE in cyclopropane at 298 K has been measured to be 106.3 ±0.3 kcal/mol (Baghal-Vayjooee, M. H.; Benson, S. W. J. Am. Chem. Soc. 1979, 101, 2838), which is nearly 8 kcal/mol larger than the BDE at 298 K of 98.6 ± 0.4 kcal/mol for a secondary C - H bond in propane ( Seakins, P. W.; Pilling, M. J.; Niiranen, J. T.; Gutman, D.; Kransoperov, L. N. J. Phys. Chem. 1992, 96, 9847). Of the several reasons considered by Baghal-Vayjooee and Benson for the unusually high C - H BDE in cyclopropane, the major cause, according to our calculations, is not a large increase in strain on forming a planar cyclopropyl radical but the unusually large amount of carbon 2s character in a cyclopropane C-H bond.
34. The C - H BDE in cyclopropane at 298 K has been measured to be 106.3 ±0.3 kcal/mol (Baghal-Vayjooee, M. H.; Benson, S. W. J. Am. Chem. Soc. 1979, 101, 2838), which is nearly 8 kcal/mol larger than the BDE at 298 K of 98.6 ± 0.4 kcal/mol for a secondary C - H bond in propane ( Seakins, P. W.; Pilling, M. J.; Niiranen, J. T.; Gutman, D.; Kransoperov, L. N. J. Phys. Chem. 1992, 96, 9847). Of the several reasons considered by Baghal-Vayjooee and Benson for the unusually high C - H BDE in cyclopropane, the major cause, according to our calculations, is not a large increase in strain on forming a planar cyclopropyl radical but the unusually large amount of carbon 2s character in a cyclopropane C-H bond.
35. It has previously been noted that the strong C - H bonds in cyclopropane reduce its apparent strain energy. Hamilton. J. G.; Palke, W. E. J. Am. Chem. Soc. 1993, 115, 4159.
36. Calculating these differences in BDEs is the same as calculating separately the changes that occur in the energies of the π C-C and σ C - H bonds in converting one isomer into the other.