Scanning Tunnellng Mlcroscopy of Self-Assembled ... - ACS Publications

(c) Tebbe, F. N.; Harlow, R. L.; Chase, D. B.; Thorn, D. L.; Campbell,. G. C., Jr.; Calabrese, J. C.; Herron, N.; Young, R. J., Jr.; Wasserman, E. Sci...
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J . Phys. Chem. 1992, 96,6110-61 11

J. R.;Preston, K. F. Science 1991, 254, 1183. ( 5 ) (a) Olah, G. A,; Bucsi, I.; Lambert, C.; Aniszfeld, R.; Trivedi, N. J.; Scnsharma, D. K.; F'rakash, G. K.S.J. Am. Chem. Soc. 1991,113,9385. (b) Tebbe, F. N.; Becker, J. Y.; Chase, D. B.; Firment, L. E.; Holler, E. R.; Malone, B. S.;Krusic, P. J.; Wasserman, E. J . Am. Chem. Soc. 1991, 113, 9900. (c) Tebbe, F. N.; Harlow, R. L.; Chase, D. B.; Thorn, D. L.; Campbell, G. C., Jr.; Calabrese, J. C.; Herron, N.; Young, R. J., Jr.; Wasserman, E. Science 1992, 256, 822. (6) (a) Suzuki, T.; Li, Q.; Khemani, K. C.; Wudl, F.; Almaesson, 0. Science 1991, 254, 1186. (b) Bausch, J. W.; Prakash, G. K. S.;Olah, G. A. J. Am. Chcm.Soc. 1991, 113, 3205. (7) Hirsh, A.; Li, Q.; Wudl, F. Angew. Chem., In?. Ed. Engl. 1991, 30, 1309. (8) Matsuzawa, N.; Dixon, D. A.; Fukunaga, T. J. Phys. Chem., in press. (9) (a) Eliel, E. L. Stereochemistry of Carbon Compounds; Mdjraw-Hill: New York, 1%2. (b) Payne, P. W.; Allen, L. C. In Applications ofEl&ronic Structure Theory;Schaefer, H. F., 111, Ed.; Plenum Press: New York, 1977; Chapter 2, p 29. (10) Dewar, M. J. S.;Zoebisch, E. G.; Healy, E. F.; Stewart, J. J. P. J . Am. Chem. Soc. 1985, 107, 3902. (11) Stewart, J. J. P. J . Comput. Chem. 1989, 10, 209, 221. (12) Matsuzawa, N.; Dixon, D. A. J . Phys. Chem., submitted for publi-

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In Ab Initio Methods in Quantum Chemistry-II; Lawley, K . P., Ed.; John Wiley & Sons: New York, 1987; p 447. (c) Wimmer, E.; Freeman, A. J.; Fu, C.-L.; Cao, P.-L.; Chou, S.-H.; Delley. B. In Supercomputer Research in Chemistry and Chemical Engineering, Jensen, K . F., Truhlar, D. G., Eds.; ACS Symposium Series 353; American Chemical Society: Washington, D.C., 1987; p 49. (d) Jones, R. 0.;Gunnarsson, 0. Rev. Mod.Phys. 1989,61,689. (e) Dixon, D. A,; Andzelm, J.; Fitzgerald, G.; Wimmer, E.; Delley, B. In Science and Engineering on Supercomputers; Pitcher, E. J., Ed.; Computa-

tional Mechanics Publications: Southampton, England, 1990; p 285. (f) Dixon, D. A.; Andzelm, J.; Fitzgerald, G.; Wimmer, E.; Jasien, P. In Density Functional Methods in Chemistry; Labanowski,J. K., Andzelm, J. W., Eds.; Springer-Verlag: New York, 1991; Cha ter 3, p 33. (16) SCF convergence criteria = 10- (PRECISE option in MOPAC). No symmetry constaints were used. (17) (a) Delley, B. J . Chem. Phys. 1990, 92, 508. DMol is available commercially from BIOSYM Technologies, San Diego, CA. The grid used in the calculations was obtained by using the MEDiuM parameter in DMol. (b) Delley, B. In Density Functional Methods in Chemistry; Labanowski, J. K.,Andzelm, J. W., Eds.; Springer-Verlag: New York, 1991; Chapter 11, p 101. (18) von Barth, U.; Hedin, L. J . Phys. C 1972, 5, 1629. (19) Brown, H. C. Record Chem. Progr. 1953, 14, 83. (20) The 1,3,5-trisubtituted trimethylmccyclohcxanestructure in C a r u is a consequence of a series of sequential '1,4-additions" under thermal equilibration (see ref 22). The pcntadienyl and cyclopcntadienyl radical structures (see ref 4) also can be regarded as results of the 1,haddition process. (21) Matsuzawa, N.; Dixon, D. A. J. Phys. Chem., submitted for publication. (22) The AMI energies for reaction 2 are -8.2, +22.3, +15.0, +10.6, and +7.2 kcal/mol for X = H, F, C1, Br, and I, respectively. Thcsc reactions are all more exothermic than predicted at the LDF level, and this will lead to exothermic values for reaction 1 for all X. (23) (a) Pedley, J. B.; Naylor, R. D.; Kirby, S.P. Thermochemical Data of Organic Compounds; Chapman and Hall: London, England, 1986. (b) Chase, M. W., Jr.; Davies, C. A.; Downey, J. R., Jr.; Frurip, D. J.; MacDonald, R. A.; Syverud, A. N. J . Phys. Chem. Ref. Data 1985, 14, Suppl. 1. (24) Matsuzawa, N.; Dixon, D. A.; Fukunaga, T. J . Phys. Chem., sub mitted for publication. Such equilibration is suggested, for example, by the observation that freshly prepared partially brominated yellowish product, C60Br