Thermodynamics of a diaminocarbene-tetraaminoethylene equilibrium [1]

Journal of the American Chemical Society

Volumn 121, Issue 45, 1999, Pages 10626-10627

  Liu, Yufa ^a   Lindner, Patrick E ^a   Lemal, David M ^a  

^a Dartmouth College   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ETHYLENE DERIVATIVE;

CHEMICAL ANALYSIS; CHEMICAL BINDING; CHEMICAL REACTION; DIMERIZATION; DISSOCIATION CONSTANT; ENTROPY; LETTER; REACTION ANALYSIS; SYNTHESIS; THERMODYNAMICS;

EID: 0033579190     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9922678     Document Type: Letter

References (44)

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4. For reviews of this early work, see: Hoffmann, R. Angew. Chem., Int. Ed. Engl. 1968, 7, 754. Wiberg, N. Angew. Chem., Int. Ed. Engl. 1968, 7, 766.
5. For reviews of this early work, see: Hoffmann, R. Angew. Chem., Int. Ed. Engl. 1968, 7, 754. Wiberg, N. Angew. Chem., Int. Ed. Engl. 1968, 7, 766.
6. Lemal, D. M. In The Chemistry of the Amino Group; Patai, S., Ed.; Interscience: New York, 1968; p 701.
7. Lemal, D. M.; Lovald, R. A.; Kawano, K. I. J. Am. Chem. Soc. 1964, 86, 2518.
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9. In a very recent paper Denk has challenged the early findings, demonstrating that crossover can indeed occur between the same pairs of tetraaminoethylenes studied independently by the groups of Lemal and Winberg (Denk, M. K.; Hatano, K.; Ma, M. Tetrahedron Lett. 1999, 40, 2057). His conclusion that the new work "supports the existence of the Wanzlick equilibrium" is flawed, however. Finding the absence of crossover is compelling evidence against unimolecular dissociation of a tetraaminoethylene, as small amounts of impurities could not inhibit such a process. On the other hand, the observation of crossover is subject to a variety of interpretations including catalyzed dissociation, e.g. via the mechanism presented in ref 5. Regarding catalysis in the present work, see ref 23.
10. (a) Arduengo, A. J., III; Harlow, R. L.; Kline, M. J. Am. Chem. Soc. 1991, 113, 361.
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14. See also: Herrmann, W. A.; Köcher, C.; Goossen, L. J.; Artus, G. R. J. Chem. Eur. J. 1996, 2, 1627. Kuhn, N.; Kratz, T. Synthesis 1993, 561.
15. See also: Herrmann, W. A.; Köcher, C.; Goossen, L. J.; Artus, G. R. J. Chem. Eur. J. 1996, 2, 1627. Kuhn, N.; Kratz, T. Synthesis 1993, 561.
16. Alder, R. W.; Blake, M. E. J. Chem. Soc., Chem. Commun. 1997, 1513.
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19. Because of its very bulky substituents, 2 (R = mesityl) does not dimerize. Arduengo, A. J., III; Goerlich, J. R.; Marshall, W. J. J. Am. Chem. Soc. 1995, 117, 11027.
20. For recent reviews on tetraaminoethylenes and diaminocarbenes, see: Warkentin, J. In Advances in Carbene Chemistry; Blinker, U. H., Ed.; Jai Press: London, 1998; Vol. 2, p 245. Herrmann, W. A.; Köcher, C. Angew. Chem., Int. Ed. Engl. 1997, 36, 2162. Regitz, M. Angew. Chem., Int. Ed. Engl. 1996, 35, 725.
21. For recent reviews on tetraaminoethylenes and diaminocarbenes, see: Warkentin, J. In Advances in Carbene Chemistry; Blinker, U. H., Ed.; Jai Press: London, 1998; Vol. 2, p 245. Herrmann, W. A.; Köcher, C. Angew. Chem., Int. Ed. Engl. 1997, 36, 2162. Regitz, M. Angew. Chem., Int. Ed. Engl. 1996, 35, 725.
22. For recent reviews on tetraaminoethylenes and diaminocarbenes, see: Warkentin, J. In Advances in Carbene Chemistry; Blinker, U. H., Ed.; Jai Press: London, 1998; Vol. 2, p 245. Herrmann, W. A.; Köcher, C. Angew. Chem., Int. Ed. Engl. 1997, 36, 2162. Regitz, M. Angew. Chem., Int. Ed. Engl. 1996, 35, 725.
23. Taton, T. A.; Chen, P. Angew. Chem., Int. Ed. Engl. 1996, 35, 1011. Chen, P. In Advances in Carbene Chemistry; Brinker, U. H., Ed.; Jai Press: London, 1998; Vol. 2, p 45. Compound 4 (n = 3) was independently synthesized in Thummel's laboratory. Shi, Z.; Goulle, V.; Thummel, R. P. Tetrahedron Lett. 1996, 37, 2357.
24. Taton, T. A.; Chen, P. Angew. Chem., Int. Ed. Engl. 1996, 35, 1011. Chen, P. In Advances in Carbene Chemistry; Brinker, U. H., Ed.; Jai Press: London, 1998; Vol. 2, p 45. Compound 4 (n = 3) was independently synthesized in Thummel's laboratory. Shi, Z.; Goulle, V.; Thummel, R. P. Tetrahedron Lett. 1996, 37, 2357.
25. Taton, T. A.; Chen, P. Angew. Chem., Int. Ed. Engl. 1996, 35, 1011. Chen, P. In Advances in Carbene Chemistry; Brinker, U. H., Ed.; Jai Press: London, 1998; Vol. 2, p 45. Compound 4 (n = 3) was independently synthesized in Thummel's laboratory. Shi, Z.; Goulle, V.; Thummel, R. P. Tetrahedron Lett. 1996, 37, 2357.
26. Recently, both a thiazol-2-ylidene and its dimer have been isolated and characterized. Arduengo, A. J., III; Goerlich, J. R.; Marshall, W. J. Liebig's Ann./Recl. 1997, 365.
27. The degree of aromaticity and of ylidic character in carbenes of type 3 remains a matter of controversy. Boehme, C.; Frenking, G. J. Am. Chem. Soc. 1996, 118, 2039. Heinemann, C.; Müller, T.; Apeloig, Y.; Schwarz, H. J. Am. Chem. Soc. 1996, 118, 2023. Sauers, R. R. Tetrahedron Lett. 1996, 37, 149. Olsson, M. H. M.; Boroski, P. Theor. Chim. Acta 1996, 93, 17. Arduengo, A. J., III; Dias, H. V. R.; Dixon, D. A.; Harlow, R.; Klooster, W. T.; Koetzle, T. F. J. Am. Chem. Soc. 1994, 116, 6812.
28. The degree of aromaticity and of ylidic character in carbenes of type 3 remains a matter of controversy. Boehme, C.; Frenking, G. J. Am. Chem. Soc. 1996, 118, 2039. Heinemann, C.; Müller, T.; Apeloig, Y.; Schwarz, H. J. Am. Chem. Soc. 1996, 118, 2023. Sauers, R. R. Tetrahedron Lett. 1996, 37, 149. Olsson, M. H. M.; Boroski, P. Theor. Chim. Acta 1996, 93, 17. Arduengo, A. J., III; Dias, H. V. R.; Dixon, D. A.; Harlow, R.; Klooster, W. T.; Koetzle, T. F. J. Am. Chem. Soc. 1994, 116, 6812.
29. The degree of aromaticity and of ylidic character in carbenes of type 3 remains a matter of controversy. Boehme, C.; Frenking, G. J. Am. Chem. Soc. 1996, 118, 2039. Heinemann, C.; Müller, T.; Apeloig, Y.; Schwarz, H. J. Am. Chem. Soc. 1996, 118, 2023. Sauers, R. R. Tetrahedron Lett. 1996, 37, 149. Olsson, M. H. M.; Boroski, P. Theor. Chim. Acta 1996, 93, 17. Arduengo, A. J., III; Dias, H. V. R.; Dixon, D. A.; Harlow, R.; Klooster, W. T.; Koetzle, T. F. J. Am. Chem. Soc. 1994, 116, 6812.
30. The degree of aromaticity and of ylidic character in carbenes of type 3 remains a matter of controversy. Boehme, C.; Frenking, G. J. Am. Chem. Soc. 1996, 118, 2039. Heinemann, C.; Müller, T.; Apeloig, Y.; Schwarz, H. J. Am. Chem. Soc. 1996, 118, 2023. Sauers, R. R. Tetrahedron Lett. 1996, 37, 149. Olsson, M. H. M.; Boroski, P. Theor. Chim. Acta 1996, 93, 17. Arduengo, A. J., III; Dias, H. V. R.; Dixon, D. A.; Harlow, R.; Klooster, W. T.; Koetzle, T. F. J. Am. Chem. Soc. 1994, 116, 6812.
31. The degree of aromaticity and of ylidic character in carbenes of type 3 remains a matter of controversy. Boehme, C.; Frenking, G. J. Am. Chem. Soc. 1996, 118, 2039. Heinemann, C.; Müller, T.; Apeloig, Y.; Schwarz, H. J. Am. Chem. Soc. 1996, 118, 2023. Sauers, R. R. Tetrahedron Lett. 1996, 37, 149. Olsson, M. H. M.; Boroski, P. Theor. Chim. Acta 1996, 93, 17. Arduengo, A. J., III; Dias, H. V. R.; Dixon, D. A.; Harlow, R.; Klooster, W. T.; Koetzle, T. F. J. Am. Chem. Soc. 1994, 116, 6812.
32. Cetinkaya, E.; Hitchcock, P. B.; Kücükbay, H.; Lappert, M. F.; Al-Juaid, S. J. Organomet. Chem. 1994, 481, 89
33. Other bis(benzimidazol-2-ylidenes) have been synthesized as well, but none has been observed to dissociate. (a) Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1994, 35, 33. Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1995, 36, 2741. Shi, Z.; Thummel, R. P. J. Org. Chem. 1995, 60, 5935. (b) Hünig, S.; Scheutzow, D.; Schlaf, H.; Quast, H. Justus Liebig's Ann. Chem. 1972, 765, 110. Hünig, S.; Scheutzow, D.; Schlaf, H. Justus Liebig's Ann. Chem. 1972, 765, 126. (c) Bourson, J. Bull. Soc. Chim. Fr. 1971, 3541.
34. Other bis(benzimidazol-2-ylidenes) have been synthesized as well, but none has been observed to dissociate. (a) Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1994, 35, 33. Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1995, 36, 2741. Shi, Z.; Thummel, R. P. J. Org. Chem. 1995, 60, 5935. (b) Hünig, S.; Scheutzow, D.; Schlaf, H.; Quast, H. Justus Liebig's Ann. Chem. 1972, 765, 110. Hünig, S.; Scheutzow, D.; Schlaf, H. Justus Liebig's Ann. Chem. 1972, 765, 126. (c) Bourson, J. Bull. Soc. Chim. Fr. 1971, 3541.
35. Other bis(benzimidazol-2-ylidenes) have been synthesized as well, but none has been observed to dissociate. (a) Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1994, 35, 33. Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1995, 36, 2741. Shi, Z.; Thummel, R. P. J. Org. Chem. 1995, 60, 5935. (b) Hünig, S.; Scheutzow, D.; Schlaf, H.; Quast, H. Justus Liebig's Ann. Chem. 1972, 765, 110. Hünig, S.; Scheutzow, D.; Schlaf, H. Justus Liebig's Ann. Chem. 1972, 765, 126. (c) Bourson, J. Bull. Soc. Chim. Fr. 1971, 3541.
36. Other bis(benzimidazol-2-ylidenes) have been synthesized as well, but none has been observed to dissociate. (a) Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1994, 35, 33. Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1995, 36, 2741. Shi, Z.; Thummel, R. P. J. Org. Chem. 1995, 60, 5935. (b) Hünig, S.; Scheutzow, D.; Schlaf, H.; Quast, H. Justus Liebig's Ann. Chem. 1972, 765, 110. Hünig, S.; Scheutzow, D.; Schlaf, H. Justus Liebig's Ann. Chem. 1972, 765, 126. (c) Bourson, J. Bull. Soc. Chim. Fr. 1971, 3541.
37. Other bis(benzimidazol-2-ylidenes) have been synthesized as well, but none has been observed to dissociate. (a) Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1994, 35, 33. Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1995, 36, 2741. Shi, Z.; Thummel, R. P. J. Org. Chem. 1995, 60, 5935. (b) Hünig, S.; Scheutzow, D.; Schlaf, H.; Quast, H. Justus Liebig's Ann. Chem. 1972, 765, 110. Hünig, S.; Scheutzow, D.; Schlaf, H. Justus Liebig's Ann. Chem. 1972, 765, 126. (c) Bourson, J. Bull. Soc. Chim. Fr. 1971, 3541.
38. Other bis(benzimidazol-2-ylidenes) have been synthesized as well, but none has been observed to dissociate. (a) Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1994, 35, 33. Shi, Z.; Thummel, R. P. Tetrahedron Lett. 1995, 36, 2741. Shi, Z.; Thummel, R. P. J. Org. Chem. 1995, 60, 5935. (b) Hünig, S.; Scheutzow, D.; Schlaf, H.; Quast, H. Justus Liebig's Ann. Chem. 1972, 765, 110. Hünig, S.; Scheutzow, D.; Schlaf, H. Justus Liebig's Ann. Chem. 1972, 765, 126. (c) Bourson, J. Bull. Soc. Chim. Fr. 1971, 3541.
39. A recent report describes the first isolation of a benzimidazol-2-ylidene, the sterically hindered N,N′-bis(2,2-dimethylpropyl) derivative. Hahn, F. E.; Wittenbecher, L.; Boese, R.; Bläser, D. Chem. Eur. J. 1999, 5, 1931.
40. 6 (ref 11).
41. Nakazawa, Y.; Sawahara, M.; Hinata, M. French patent 1,534,386 (1968); Chem. Abstr. 1969, 71, 126008t.
42. Nakazawa, Y.; Sawahara, M.; Hinata, M. French patent 1,534,386 (1968); Chem. Abstr. 1969, 71, 126008t.
43. Concentrations were corrected for the volume expansion of the solvent with temperature.
44. These measurements were feasible because of adventitious catalysis of the equilibrium, presumably by a trace electrophile. When potassium hydride was added to test for catalysis, establishment of equilibrium became impractically slow. This reagent has been used to prevent acid-catalyzed dissociation of a bis(thiazol-2-ylidene); see ref 15.