Chiral molecules with achiral excited states: A computational study of 1,3-dimethylaliene

Journal of Physical Chemistry A

Volumn 105, Issue 41, 2001, Pages 9509-9517

  Deretey, Eugen ^a   Shapiro, Moshe ^b   Brumer, Paul ^a  

^a UNIVERSITY OF TORONTO   (Canada)

^b WEIZMANN INSTITUTE OF SCIENCE   (Israel)

Author keywords

[No Author keywords available]

Indexed keywords

CHIRAL MOLECULES; RACEMIZATION REACTIONS;

AROMATIC COMPOUNDS; CHEMICAL BONDS; COMPUTATIONAL METHODS; GROUND STATE; LASER APPLICATIONS;

MOLECULAR STRUCTURE;

EID: 0035909748     PISSN: 10895639     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp010557g     Document Type: Article

References (31)

1. Maierle, C. S.; Harris, R. A. J. Chem. Phys. 1998,109,3713;
2. Cina, J. A.; Harris, R. A. J. Chem. Phys. 1994, 700, 2531.
3. Quack, M. Angew. Chem. Ed. Engt. 1989, 28, 571.
4. Shapiro, M.; Frishman, E.; Brumer, P. Phys. Rev. Lett. 2000, 84, 1669.
5. Fujimura Y.; Gonzalez, L.; Hoki, K.; Manz, J.; Ohtsuki, Y. Chem. Phys. Lett. 1999,306, 1.
6. Salam A.; Meath, W. J. J. Chem. Phys. 1997, 706, 7865;
7. Salam A.; Meath, W. J. J. Chem. Phys. 1998, 228, 115.
8. D. Gerbasi, M. Shapiro and P. Brumer, (manuscript in preparation).
9. Rauk, A.; Drake, A. F.; Mason, S. F. J. Am. Chem. Soc. 1979, 707, 2284.
10. Roth, W. R.; Bastigkeit, T. Liebigs Ann. Chem. 1996, 2171.
11. Iverson, A. A.; Rüssel, B. R. Spectrochim. Acta, Part A 1972, 284, 447.
12. Fuke, K.; Schnepp, O. Chem. Phys. 1979, 38, 211.
13. Baltzer, P.; Wannberg, B.; Lundqvist, M.; Karlsson, L.; Holland, D. M. P.; MacDonald, M. A.; von Niessen, W. Chem. Phys. 1995, 790, 551.
14. Bawagan, A. D. O.; Ghanty, T. K.; Davidson, E. R.; Tan, K. H. Chem. Phys. Lett. 1998, 287, 61.
15. Holland, D. M. P.; Shaw, D. A. Chem. Phys. 1999, 243, 333.
16. Mahapatra, S.; Cederbaum, L. S.; Koppel, H. J. Chem. Phys. 1999, 7/7, 10452.
17. Seeger, R.; Krishnan, R.; Pople, J. A.; Schleyer, P.V.R. J. Am. Chem. Soc. 1977, 99, 7103.
18. Bettinger, H. F.; Schreiner, P. R.; Schleyer, P.V.R.; Schaefer, III, H. F. J. Phys. Chem. 1996, 700, 16147.
19. Bettinger, H. F.; Schreiner, P. R.; Schleyer, P. v. R.; Schaefer, III, H. F. J. Org. Chem. 1997, 62, 9267.
20. Jackson, W. M.; Mebel, A. M.; Lin, S. H.; Lee, Y. T. J. Phys. Chem. 1997, 101, 6638 and references wherein.
21. Otto, P.; Ruiz, M. B. J. Mol. Struct. (THEOCHEM) 1998, 433, 131.
22. Foresman, J. B.; Head-Gordon, M.; Pople, J. A.; Frisch, M. J. J. Phys. Chem. 1992, 96, 135.
23. Stanton, J. F.; Gauss, J.; Ishikawa, N.; Head-Gordon, M. J. Chem. Phys. 1995, 103, 4160.
24. Schlegel, H. B.; Robb, M. A. Chem. Phys. Lett. 1982, 93, 43.
25. Bernardi, F.; Bottoni, A.; McDougall, J. J. W.; Robb, M. A.; Schlegel, H. B. Faraday Symp. Chem. Soc. 1984, 19, 137.
26. 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.; HeadGordon, M.; Gonzalez, C., Pople, J. A. Gaussian 94, Revision D.4; Gaussian, Inc.: Pittsburgh, PA, 1995.
27. Schaftenaar, G.; Noordik, J. H. J. Comput.-Aided Mol. Des. 2000, 14, 123.
28. The optimization of the 2a geometry yielded two CASSCF(4, 6) structures, both of them having mostly (1,2)(1,2) configuration. The higherenergy structure, with Ecas = -193.867624, has a CAS coefficient of 0.999, indicating that it is completely dominated by the (1,2)(1,2) configuration. This structure has three imaginary frequencies. The C-C bond-length and the C-C-C bending angle are 1.318 A and 179.634°, respectively. The lower energy structure, with £cas = - 193.888821 hartree, has a CAS coefficient of 0.982. In this case the main (1,2)(1,2) configuration is mixed with the doubly-excited (1,3)(1,3) configuration. The lower energy structure has four imaginary frequencies. The C-C bond-length and the C-C-C bending angle are 1.329 A and 179.690°, respectively. In this structure the symmetries of the active space orbitals changed from (AAA'A'A'A') to (AAAA'A'A'). The closeness of the two structures suggests the existence of an avoided curve-crossing or of a conical intersection near the 2a conformation.
29. The central C=C=C carbon atom defines the origin of XYZ axis. The C=C=C group is located along the Z axis, the X axis is contained in the frozen plane defined by CHs-C-H group and the K axis is orthogonal to this plane.
30. In the ground state, the distance between the two carbons belonging to the two methyl groups in the syn configuration is 4.32 A. The smallest distance between two hydrogens belonging to the two methyls is 3.06 A. These distances are well outside the sum of the van der Waals radii of two carbon atoms, which is 3.40 A and that of two hydrogen atoms which is 2.40 A.
31. On the basis of previous DFT calculations for the nonsubstituted aliène, where a first-excited-state minimum in the planar-linear configuration was found, we have used the DFT method to optimize the planar geometries of 1,3-dimethylallene. Since the DFT methods is strictly applicable to ground closed-shell configurations, the use of DFT for excited-state calculations might appear questionable. However, in our case, the excited-state geometries have closed shell electronic states, for which DFT is applicable. Using DFT in conjunction with the B3LYP method with a smaller basis set [6-31+G(d, p)] yielded a iionplanar minimum energy geometry of the CiSymmetry, with the two C-H hydrogen atoms oriented out-of-plane. This finding was confirmed by a preliminary CASSCF optimization, yielding a critical point at a nonplanar conformation.