Why the Classical and Nonclassical Norbornyl Cations Do Not Resemble the 2-endo- and 2-exo-Norbornyl Solvolysis Transition States

Journal of Organic Chemistry

Volumn 62, Issue 13, 1997, Pages 4216-4228

  Schreiner, Peter R ^a,b,c   Von Ragué Schleyer, Paul ^a,b   Schaefer, Henry F ^a  

^a UNIVERSITY OF GEORGIA   (United States)

^b UNIVERSITY OF ERLANGEN NUREMBERG   (Germany)

^c UNIVERSITY OF GÖTTINGEN   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 1542426862     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo9613388     Document Type: Article

References (99)

1. Winstein, S.; Trifan, D. S. J. Am. Chem. Soc. 1949, 71, 2953; 1952, 74, 1147, 1154.
2. Winstein, S.; Trifan, D. S. J. Am. Chem. Soc. 1949, 71, 2953; 1952, 74, 1147, 1154.
3. 5 See: Roberts, J. D.; Mazur, R. H. J. Am. Chem. Soc. 1951, 73, 3542.
4. Brown, H. C., with comments by Schleyer, P. v. R. The Nonclassical Ion Problem; Plenum: New York, 1977. For other reviews, see refs 6 and 12.
5. (a) Lenoir, D.; Apeloig, Y.; Arad, D.; Schleyer, P. v. R. J. Org. Chem. 1988, 53, 661; this paper is the latest available review on the norbornyl solvolysis literature.
6. (b) Brown, H. C. Acc. Chem. Res. 1986, 19, 34.
7. (c) Barkhash, V. A. Topics in Current Chemistry; Springer: Berlin, 1984; Vol. 116/117, pp 1-249.
8. (d) Saunders, M.; Kates, M. R. J. Am. Chem. Soc. 1983, 105, 3571.
9. (e) Lenoir, D. Nachr. Chem. Tech. Lab. 1983, 31, 889.
10. (f) Walling, C. Acc. Chem. Res. 1983, 16, 448.
11. (g) Olah, G. A.; Prakash, G. K. S.; Arvanaghi, M.; Anet, F. A. L. J. Am. Chem. Soc. 1982, 104, 7105.
12. (h) Lyerla, J. R.; Yannoni, C. S.; Fyfe, C. A. Acc. Chem. Res. 1982, 15, 208.
13. (i) Kirmse, W. Topics in Current Chemistry; Springer: Berlin, 1979; Vol. 80, p 128.
14. (j) Olah, G. A. Topics in Current Chemistry; Springer: Berlin, 1979; also see ref 11.
15. The first good evidence for such ion pair intermediates in related terpene rearrangements had been presented by Nevell, T. P.; deSalas, E.; Wilson, C. L. J. Chem. Soc. 1939, 1188.
16. Ikegami, S.; Van der Jagt, D. L.; Brown, H. C. J. Am. Chem. Soc. 1968, 90, 7124.
17. Brown, H. C.; Takeuchi, K. J. Am. Chem. Soc. 1968, 90, 2691.
18. Brown, H. C.; Chloupek, F. J. J. Am. Chem. Soc. 1963, 85, 2322.
19. (a) Bentley, T. W.; Bowen, C. T.; Morten, D. H.; Schleyer, P. v. R. J. Am. Chem. Soc. 1981, 103, 5466.
20. (b) Bentley, T. W.; Carter, G. E. J. Org. Chem. 1983, 48, 579.
21. For a historical account, see: Olah, G. A. Angew. Chem. 1995, 107, 1519. Also see: (a) Olah, G. A., Schleyer, P. v. R., Eds. Carbonium Ions; Wiley-Interscience: New York, 1968-1976; Vol. I-IV. (b) Olah, G. A. Carbocations and Electrophilic Reactions; Verlag Chemie: Weinheim, 1974. (c) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New York, 1985. (d) Olah, G. A.; Molnár, A. Hydrocarbon Chemistry; Wiley: New York, 1995. (e) Olah, G. A.; Prakash, G. K. S.; Williams, R. E.; Field, L. D.; Wade, K. Hypercarbon Chemistry; Wiley: New York, 1987.
22. For a historical account, see: Olah, G. A. Angew. Chem. 1995, 107, 1519. Also see: (a) Olah, G. A., Schleyer, P. v. R., Eds. Carbonium Ions; Wiley-Interscience: New York, 1968-1976; Vol. I-IV. (b) Olah, G. A. Carbocations and Electrophilic Reactions; Verlag Chemie: Weinheim, 1974. (c) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New York, 1985. (d) Olah, G. A.; Molnár, A. Hydrocarbon Chemistry; Wiley: New York, 1995. (e) Olah, G. A.; Prakash, G. K. S.; Williams, R. E.; Field, L. D.; Wade, K. Hypercarbon Chemistry; Wiley: New York, 1987.
23. For a historical account, see: Olah, G. A. Angew. Chem. 1995, 107, 1519. Also see: (a) Olah, G. A., Schleyer, P. v. R., Eds. Carbonium Ions; Wiley-Interscience: New York, 1968-1976; Vol. I-IV. (b) Olah, G. A. Carbocations and Electrophilic Reactions; Verlag Chemie: Weinheim, 1974. (c) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New York, 1985. (d) Olah, G. A.; Molnár, A. Hydrocarbon Chemistry; Wiley: New York, 1995. (e) Olah, G. A.; Prakash, G. K. S.; Williams, R. E.; Field, L. D.; Wade, K. Hypercarbon Chemistry; Wiley: New York, 1987.
24. For a historical account, see: Olah, G. A. Angew. Chem. 1995, 107, 1519. Also see: (a) Olah, G. A., Schleyer, P. v. R., Eds. Carbonium Ions; Wiley-Interscience: New York, 1968-1976; Vol. I-IV. (b) Olah, G. A. Carbocations and Electrophilic Reactions; Verlag Chemie: Weinheim, 1974. (c) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New York, 1985. (d) Olah, G. A.; Molnár, A. Hydrocarbon Chemistry; Wiley: New York, 1995. (e) Olah, G. A.; Prakash, G. K. S.; Williams, R. E.; Field, L. D.; Wade, K. Hypercarbon Chemistry; Wiley: New York, 1987.
25. For a historical account, see: Olah, G. A. Angew. Chem. 1995, 107, 1519. Also see: (a) Olah, G. A., Schleyer, P. v. R., Eds. Carbonium Ions; Wiley-Interscience: New York, 1968-1976; Vol. I-IV. (b) Olah, G. A. Carbocations and Electrophilic Reactions; Verlag Chemie: Weinheim, 1974. (c) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New York, 1985. (d) Olah, G. A.; Molnár, A. Hydrocarbon Chemistry; Wiley: New York, 1995. (e) Olah, G. A.; Prakash, G. K. S.; Williams, R. E.; Field, L. D.; Wade, K. Hypercarbon Chemistry; Wiley: New York, 1987.
26. For a historical account, see: Olah, G. A. Angew. Chem. 1995, 107, 1519. Also see: (a) Olah, G. A., Schleyer, P. v. R., Eds. Carbonium Ions; Wiley-Interscience: New York, 1968-1976; Vol. I-IV. (b) Olah, G. A. Carbocations and Electrophilic Reactions; Verlag Chemie: Weinheim, 1974. (c) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New York, 1985. (d) Olah, G. A.; Molnár, A. Hydrocarbon Chemistry; Wiley: New York, 1995. (e) Olah, G. A.; Prakash, G. K. S.; Williams, R. E.; Field, L. D.; Wade, K. Hypercarbon Chemistry; Wiley: New York, 1987.
27. (a) Schleyer, P. v. R.; Watts, W. E.; Fort, R. C., Jr.; Comisarow, M. B.; Olah, G. A. J. Am. Chem. Soc. 1964, 86, 4195.
28. (b) Saunders, M.; Schleyer, P. v. R.; Olah, G. A. J. Am. Chem. Soc. 1964, 86, 5680.
29. (c) Olah, G. A.; White, A. M.; DeMember, J. R.; Commeyras, A.; Lui, C. Y. J. Am. Chem. Soc. 1970, 92, 4627.
30. (d) Olah, G. A.; Prakash, G. K. S.; Arvanaghi, M.; Anet, F. A. L. J. Am. Chem. Soc. 1982, 104, 7105.
31. (e) Olah, G. A.; Prakash, G. K. S.; Saunders, M. Acc. Chem. Res. 1983, 16, 440.
32. 6 distances; see. Laube, T. Angew. Chem. 1986, 98, 368.
33. (a) Olah, G. A.; Mateescu, G. D.; Wilson, L. A.; Gross, M. H. J. Am. Chem. Soc. 1970, 92, 4627.
34. (b) Olah, G. A.; Mateescu, G. D.; Riemenschneider, J. L. J. Am. Chem. Soc. 1972, 94, 2529.
35. (c) Johnson, S. A.; Clark, D. T. J. Am. Chem. Soc. 1988, 110, 4112.
36. (d) Saunders, M.; Kates, M. R. J. Am. Chem. Soc. 1980, 102, 6867.
37. (e) Saunders, M.; Johnson, C. S., Jr. J. Am. Chem. Soc. 1987, 109, 4401.
38. (f) Yannoni, C. S.; Macho, V.; Myhre, P. C. J. Am. Chem. Soc. 1982, 104, 7380.
39. (a) Sieber, S.; Buzek, P.; Schleyer, P. v. R.; Koch, W.; Carneiro, J. W. de M. J. Am. Chem. Soc. 1993, 115, 259.
40. (b) Schleyer, P. v. R.; Sieber, S. Angew. Chem. 1993, 32, 1606 and earlier references cited therein.
41. (c) Koch, W.; Liu, B.; DeFrees, D. J. J. Am. Chem. Soc. 1989, 111, 1527.
42. (d) Koch, W.; Liu, B.; DeFrees, D. J.; Sunko, D. E.; Vancik, H. Angew. Chem. 1990, 102, 198.
43. (e) Raghavachari, K.; Haddon, R. C.; Schleyer, P. v. R.; Schaefer, H. F. J. Am. Chem. Soc. 1983, 105, 5915.
44. (a) Flury, P.; Grob, C. A.; Wang, G. Y.; Lennartz, H.-W.; Roth, W. R. Helv. Chim. Acta 1988, 71, 1017.
45. (b) Bielmann, R.; Fuso, F.; Grob, C. A. Helv. Chim. Acta 1988, 71, 312.
46. (c) Altmann-Schaffner, E.; Grob, C. A. Helv. Chim. Acta 1987, 70, 43.
47. (d) Fuso, F.; Grob, C. A.; Sawlewicz, P.; Yao, G. W. Helv. Chim. Acta 1986, 69, 2098.
48. (e) Grob, C. A. Helv. Chim. Acta 1983, 66, 3139.
49. This contradicts the common assumption, reflected in the comment of a referee: "Chemists know well that in any reaction, including solvolysis, the structure of the intermediate is a most important guiding post for the nature of the transition state." This has long been known not to be the case for 2-endo-norbornyl solvolysis (see, e.g., Olah, G. A. Acc. Chem. Res. 1975, 8, 413), and we show that this is not the case for 2-exo-norbornyl solvolysis as well.
50. (a) Bentley, T. W.; Schleyer, P. v. R. Adv. Phys. Org. Chem. 1977, 14, 1.
51. (b) Bentley, T. W.; Schleyer, P. v. R. J. Am. Chem. Soc. 1976, 98, 7658.
52. (c) Schadt, F. L.; Bentley, T. W.; Schleyer, P. v. R. J. Am. Chem. Soc. 1976, 98, 7667.
53. Bridging in the norbornyl cation system implies movement of C6 from C1 toward C2; the C1-C6 distance lengthens, and the C2-C6 (as well as the C1-C2) bond shortens. These changes, of course, are accompanied by delocalization of the C1-C6 electron density. The important consequences of a symmetrical bridge, e.g., in the 2-norbornyl cation, include the loss of chirality. Schleyer and Olah have stressed the continuum of bridging possibilities in carbocations: Schleyer, P. v. R.; Lenoir, D.; Mison, P.; Liang, G.; Prakash, G. K. S.; Olah, G. A. J. Am. Chem. Soc. 1980, 102, 683.
54. -1 lower in energy than the endo-TS; see: Goering, H. L.; Schewene, C. B. J. Am. Chem. Soc. 1965, 87, 3516.
55. Sieber, S. Dissertation, Erlangen, 1994.
56. Kirmse, W.; Minkner, D. Angew. Chem., Int. Ed. Engl. 1993, 32, 385.
57. 1) norbornyl cation minimum does not exist even at the HF/6-31G* level.
58. Arnett, E. M.; Petro, C.; Schleyer, P. v. R. J. Am. Chem. Soc. 1979, 101, 522; see also ref 11.
59. Müller, P.; Milin, D.; Feng, W. Q.; Houriet, R.; Della, E. W. J. Am. Chem. Soc. 1992, 114, 6169. A very recent study reports a smaller slope (0.7) for a plot of the Gibbs free energy changes of the deprotonation reactions of substituted cumyl cations in solution and in the gas phase; see: Richards, J. P.; Jagannadham, V.; Amyes, T. L.; Mishima, M.; Tsuno, Y. J. Am. Chem. Soc. 1994, 116, 6706. A slope of 0.52 for formolysis of allyl chlorides vs the heats of deprotonation of the cation was reported by Mayr, H.; Förner, W.; Schleyer, P. v. R. J. Am. Chem. Soc. 1979, 101, 6032.
60. Müller, P.; Milin, D.; Feng, W. Q.; Houriet, R.; Della, E. W. J. Am. Chem. Soc. 1992, 114, 6169. A very recent study reports a smaller slope (0.7) for a plot of the Gibbs free energy changes of the deprotonation reactions of substituted cumyl cations in solution and in the gas phase; see: Richards, J. P.; Jagannadham, V.; Amyes, T. L.; Mishima, M.; Tsuno, Y. J. Am. Chem. Soc. 1994, 116, 6706. A slope of 0.52 for formolysis of allyl chlorides vs the heats of deprotonation of the cation was reported by Mayr, H.; Förner, W.; Schleyer, P. v. R. J. Am. Chem. Soc. 1979, 101, 6032.
61. Müller, P.; Milin, D.; Feng, W. Q.; Houriet, R.; Della, E. W. J. Am. Chem. Soc. 1992, 114, 6169. A very recent study reports a smaller slope (0.7) for a plot of the Gibbs free energy changes of the deprotonation reactions of substituted cumyl cations in solution and in the gas phase; see: Richards, J. P.; Jagannadham, V.; Amyes, T. L.; Mishima, M.; Tsuno, Y. J. Am. Chem. Soc. 1994, 116, 6706. A slope of 0.52 for formolysis of allyl chlorides vs the heats of deprotonation of the cation was reported by Mayr, H.; Förner, W.; Schleyer, P. v. R. J. Am. Chem. Soc. 1979, 101, 6032.
62. Winstein, S. J. Am. Chem. Soc. 1965, 87, 381; ..."there are good reasons to expect carbon bridging to lag behind C-X elongation at the transition state."
63. Jorgensen, W. L.; Buckner, J. K.; Huston, S. E.; Rossky, P. J. J. Am. Chem. Soc. 1987, 109, 1891.
64. Schreiner, P. R.; Severance, D. L.; Jorgensen, W. L.; Schleyer, P. v. R.; Schaefer, H. F. J. Am. Chem. Soc. 1995, 117, 2663.
65. For reviews: see: Beveridge, D. L.; DiCapua, F. M. Annu. Biophys. Biophys. Chem. 1989, 18, 431. Allen, M. P.; Tildesley, D. J. Computer Simulation of Liquids; Clarendon Press: Oxford, Englnd, 1987. Zwanzig, R. W. J. Chem. Phys. 1954, 22, 1420.
66. For reviews: see: Beveridge, D. L.; DiCapua, F. M. Annu. Biophys. Biophys. Chem. 1989, 18, 431. Allen, M. P.; Tildesley, D. J. Computer Simulation of Liquids; Clarendon Press: Oxford, Englnd, 1987. Zwanzig, R. W. J. Chem. Phys. 1954, 22, 1420.
67. For reviews: see: Beveridge, D. L.; DiCapua, F. M. Annu. Biophys. Biophys. Chem. 1989, 18, 431. Allen, M. P.; Tildesley, D. J. Computer Simulation of Liquids; Clarendon Press: Oxford, Englnd, 1987. Zwanzig, R. W. J. Chem. Phys. 1954, 22, 1420.
68. Jorgensen, W. L. BOSS, Version 3.42; Yale University: New Haven, CT, 1994.
69. Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785.
70. Becke, A. D. Phys. Rev. A 1988, 38, 3098.
71. (a) Frisch, M. J.; Trucks, G. W.; Head-Gordon, M.; Gill, P. M. W.; Wong, M. W.; Foresman, J. B.; Johnson, B. G.; Schlegel, H. B.; Robb, M. A.; Replogle, R. S.; Gomperts, R.; Andres, J. L.; Raghavachari, K.; Binkley, J. S.; Gonzalez, C.; Martin, R. L.; Fox, D. J.; Defrees, D. J.; Baker, J.; Stewart, J. J. P.; Pople, J. A. Gaussian 92, Revision C; Gaussian, Inc.: Pittsburgh, PA, 1992.
72. (b) 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.; Cioslowski, J.; Stefanov, B. B.; Nanayakkara, A.; Challacombe, M.; 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.2; Gaussian, Inc.: Pittsburgh, PA, 1995.
73. Pople, J. A.; Krishnan, R.; Schlegel, H. B.; Binkley, J. S. Int. J. Quant. Chem. Symp. 1979, S13, 225.
74. Feller, D. J. Chem. Phys. 1992, 96, 6104.
75. Boys, S. F.; Bernardi, F. Mol. Phys. 1970, 18, 553.
76. Hehre, W. J.; Radom, L.; Pople, J. A.; Schleyer, P. v. R. Ab Initio Molecular Orbital Theory; John Wiley & Sons, Inc.: New York, 1986. Møller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. Binkley, J. S.; Pople, J. A. Int. J. Quant. Chem. 1975, 9, 229. Pople, J. A.; Binkley, J. S.; Seeger, R. Int. J. Quant. Chem. 1976, S10, 1.
77. Hehre, W. J.; Radom, L.; Pople, J. A.; Schleyer, P. v. R. Ab Initio Molecular Orbital Theory; John Wiley & Sons, Inc.: New York, 1986. Møller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. Binkley, J. S.; Pople, J. A. Int. J. Quant. Chem. 1975, 9, 229. Pople, J. A.; Binkley, J. S.; Seeger, R. Int. J. Quant. Chem. 1976, S10, 1.
78. Hehre, W. J.; Radom, L.; Pople, J. A.; Schleyer, P. v. R. Ab Initio Molecular Orbital Theory; John Wiley & Sons, Inc.: New York, 1986. Møller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. Binkley, J. S.; Pople, J. A. Int. J. Quant. Chem. 1975, 9, 229. Pople, J. A.; Binkley, J. S.; Seeger, R. Int. J. Quant. Chem. 1976, S10, 1.
79. Hehre, W. J.; Radom, L.; Pople, J. A.; Schleyer, P. v. R. Ab Initio Molecular Orbital Theory; John Wiley & Sons, Inc.: New York, 1986. Møller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. Binkley, J. S.; Pople, J. A. Int. J. Quant. Chem. 1975, 9, 229. Pople, J. A.; Binkley, J. S.; Seeger, R. Int. J. Quant. Chem. 1976, S10, 1.
80. Laube, T. Helv. Chim. Acta 1994, 77, 943.
81. Schleyer, P. v. R.; Maerker, C. Pure Appl. Chem. 1995, 67, 755. See also: Schleyer, P. v. R.; Maerker, C.; Buzek, P.; Sieber, S. Accurate Carbocation Structures: Verification of Computed Geometries by NMR, IR, and X-Ray Diffraction. In Stable Carbocations; Prakash, G. K. S., Schleyer, P. v. R., Eds.; Wiley: New York, 1997.
82. Schleyer, P. v. R.; Maerker, C. Pure Appl. Chem. 1995, 67, 755. See also: Schleyer, P. v. R.; Maerker, C.; Buzek, P.; Sieber, S. Accurate Carbocation Structures: Verification of Computed Geometries by NMR, IR, and X-Ray Diffraction. In Stable Carbocations; Prakash, G. K. S., Schleyer, P. v. R., Eds.; Wiley: New York, 1997.
83. -1 (Table 2).
84. i are the 3N - 6 vibrational frequencies of the molecule. Only 3N - 7 (one mode is imaginary and is not counted) vibrations are summed into the ZPVE for a transition structure, leading to a small error if the activation barrier on the potential energy surface (PES) is sufficiently high, and the absolute value of the imaginary vibration is small. For our flat potential energy surfaces, however, this precondition is not met as a strong bond (C-O) is broken (correlating to a high in), leading to a large change in the ZPVEs for the ground vs the transition structure. For completeness, we have given the ZPVEs in Table 2; Figure 2 also contains the relative energies for the ground states corrected for ZPVE in parentheses.
85. Kebarle, P. Annu. Rev. Phys. Chem. 1977, 28, 445.
86. Yamataka, H.; Ando, T.; Nagase, S.; Hanamura, M.; Morokuma, K. J. Org. Chem. 1984, 49, 631.
87. For an early review on nucleophilic substitution, see: Ingold, C. K. Structure and Mechanism in Organic Chemistry, 2nd ed.; Cornell University Press: New York, 1969.
88. Schreiner, P. R. Dissertation, Universität Erlangen-Nürnberg, 1994.
89. exo, which is geometrically still at a considerable distance from the fully bridged ion, has almost the same energy as the nonclassical ion.
90. Foresman, J. B.; Frisch, Æ. Exploring Chemistry with Electronic Structure Methods: A Guide to Using Gaussian; Gaussian Inc.: Pittsburgh, PA, 1993.
91. -1.
92. -1. Thus, 3 behaves like a typical secondary alkyl cation.
93. Brown, H. C.; Rei, M.-H. J. Am. Chem. Soc. 1968, 90, 6216.
94. Lias, S. G.; Bartmess, J. E.; Liebman, J. F.; Holmes, J. L.; Levin, R. D.; Mallard, W. G. J. Phys. Chem. Ref. Data 1988, 17, (Suppl. 1), 1.
95. (a) Schleyer, P. v. R.; Woodworth, C. W. J. Am. Chem. Soc. 1968, 90, 6528.
96. (b) Lancelot, C. J.; Harper, J. J.; Schleyer, P. v. R. J. Am. Chem. Soc. 1969, 91, 4294,
97. (c) Apeloig, Y.; Arad, D.; Lenoir, D.; Schleyer, P. v. R. Tetrahedron Lett. 1981, 22, 879.
98. (d) Lenoir, D.; Apeloig, Y.; Arad, D.; Schleyer, P. v. R. J. Org. Chem. 1988, 53, 661.
99. Schleyer, P. v. R.; Trifan, D. S.; Bacskai, R. J. Am. Chem. Soc. 1958, 80, 6691.