Attractions and repulsions in molecular crystals: What can be learned from the crystal structures of condensed ring aromatic hydrocarbons?

Accounts of Chemical Research

Volumn 32, Issue 8, 1999, Pages 677-684

  Dunitz, Jack D ^a   Gavezzotti, Angelo ^b  

^a ETH ZURICH   (Switzerland)

^b UNIVERSITY OF MILAN   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

BENZENE DERIVATIVE; HYDROCARBON; NAPHTHALENE DERIVATIVE;

CALCULATION; CRYSTAL STRUCTURE; MOLECULAR DYNAMICS; MOLECULAR INTERACTION; MOLECULAR RECOGNITION; MOLECULAR SIZE; REVIEW; STRUCTURE ANALYSIS;

EID: 0032821956     PISSN: 00014842     EISSN: None     Source Type: Journal    
DOI: 10.1021/ar980007+     Document Type: Review

References (37)

1. Majer, V.; Svoboda, V. IUPAC Chemical Data Series No. 32; Blackwell Scientific Publications: Boston, MA, 1985.
2. -1 for each additional methylene group. See also: Filippini, G.; Gavezzotti, A.; Simonetta, M.; Mason, R. Lattice Energies of Crystals of n.Alkanes: Molecular Motions, Defects and Phase Transitions. Nouv. J. Chim. 1981, 5, 211-217.
3. Chickos, J. S. Heats of Sublimation. In Molecular Structure and Energetics; Liebman, J. F., Greenberg, A., Eds.; Verlag Chemie: Weinheim, 1987; Vol. 2.
4. Since the molecular weight (MW) of alkanes also depends linearly on the number N of carbon atoms, it follows that enthalpies of vaporization and sublimation per gram of substance, ΔH°(vap)/MW and ΔH°(sub)/MW, remain essentially constant through-out the series.
5. The Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, England, produces and distributes the Cambridge Structural Database (CSD), which contains, in computer-readable form, unit cell dimensions, space groups, atomic coordinates, and bibliographic data for organic and organometallic crystals of known structure, plus software for retrieval, visualization, and statistical analysis of the results. The CSD contains almost 200 000 entries and is expanding by about 20 000 entries annually.
6. Gavezzotti, A. Are Crystal Structures Predictable? Acc. Chem. Res. 1994, 27, 309-314.
7. Since we are interested in comparing intermolecular distances, which are temperature-dependent quantities, we chose results of structure determinations at room temperature or as close as possible. Structures showing pronounced disorder effects were excluded. The CSD refcodes are BENZEN, NAPH-TA10, PHENAN12, ANTCEN07, PYRENE02, CRYSEN01, BZPHAN, BNPYRE10, DBNTHR01, DBNTHR10, ZZZOYC01, CORONE02, TEBNAPIO, DBPERY, TBZPYR, DNAPAN, OVALEN01, CORXAI10, DBZCOR, TBZPER, QUATER10, HBZCOR01, DUPHAX, and KEKULN10.
8. Filippini, G.; Gavezzotti, A. Empirical Intermolecular Potentials for Organic Crystals: The '6-exp' Approximation Revisited. Acta Crystallogr. 1993, B49, 868-880. Ideally, calculated lattice energies should be scaled to sublimation enthalpies at 0 K, but experimental estimates of the latter quantity are practically nonexistent. Sublimation enthalpies at 300 K are available for several hundred organic crystals (ref 3), but this is only a tiny fraction of those of known structure.
9. CRC Handbook of Chemistry and Physics, 73rd ed.; Lide, D. R., Ed.; CRC Press: Boca Raton, FL, 1992.
10. Kitaigorodskii, A. I. Molecular Crystals and Molecules; Academic Press: New York, 1973.
11. Despite the introduction of techniques such as scanning tunneling microscopy (STM), atomic force microscopy (AFM), and low-energy electron diffraction (LEED), the structure of molecular crystal surfaces is not known in sufficient detail to enable the accurate determination of intermolecular contact distances between and within surface layers. However, it seems clear that crystal surfaces tend to have low packing density and often exhibit a high degree of mobility approaching that of a liquid: Somorjai, G. A. Introduction to Surface Chemistry and Catalysis; Wiley: Interscience: New York, 1994; p 42.
12. The crystal structure of pyrene (pyrene I) has been the subject of several investigations by both X-ray and neutron diffraction, and there seems no doubt that it contains an anomalously short intermolecular H-H contact distance (2.03-2.07 Å). The exact value depends on which analysis one chooses and how the hydrogen positions are estimated. The structure is built from pairs of pyrene molecules associated into well-defined dimers across inversion centers. On cooling below about 100 K, pyrene I undergoes a first-order transition to a closely related structure in which very similar dimeric units alter their relative orientation in such a way as to alleviate the anomalously short H⋯H distance, which is actually longer in the low-temperature structure than at room temperature. See: Knight, K. S.; Shankland, K.; David, W. I. F.; Shankland, N.; Love, S. W. The Crystal Structure of Perdeuterated Pyrene II at 4.2 K. Chem. Phys. Lett. 1996, 258, 490-494.
13. Rowland, R. S.; Taylor, R. Intermolecular Non-bonded Contact Distances in Organic Crystal Structures: Comparison with Distances Expected from van der Waals Radii. J. Phys. Chem. 1996, 100, 7384-7391.
14. Kitaigorodskii, A. I. Organic Chemical Crystallography; Consultants Bureau: New York, 1961.
15. The packing coefficient of graphite can be taken as equal to or slightly less than 1, depending on the i value adopted for the "thickness" of a carbon atom in a graphite layer.
16. Estimated from results by Jeffrey et al. (Jeffrey, G. A.; Ruble, J. R.; McMullan, R. K.; Pople, J. A. The Crystal Structure of Deuterated Benzene. Proc. R. Soc. London 1987, A414, 47-57) (hexadeuteriobenzene at 15 K) and by Cox et al. (Cox, E. G.; Cruickshank, D. W. G.; Smith, J. A. S. The Crystal Structure of Benzene at -3 °C. Proc. R. Soc. London 1958, A247, 1-21) (benzene at 270 K). The value 0.68 in our compilation (Figure 5) is based on a study at 218 K by Bacon et al. (Bacon, G. E.; Curry, N. A.; Wilson, S. A. A Cristallographic Study of Solid Benzene by Neutron Diffraction. Proc. R. Soc. London 1964, A279, 98-110).
17. Estimated from results by Jeffrey et al. (Jeffrey, G. A.; Ruble, J. R.; McMullan, R. K.; Pople, J. A. The Crystal Structure of Deuterated Benzene. Proc. R. Soc. London 1987, A414, 47-57) (hexadeuteriobenzene at 15 K) and by Cox et al. (Cox, E. G.; Cruickshank, D. W. G.; Smith, J. A. S. The Crystal Structure of Benzene at -3 °C. Proc. R. Soc. London 1958, A247, 1-21) (benzene at 270 K). The value 0.68 in our compilation (Figure 5) is based on a study at 218 K by Bacon et al. (Bacon, G. E.; Curry, N. A.; Wilson, S. A. A Cristallographic Study of Solid Benzene by Neutron Diffraction. Proc. R. Soc. London 1964, A279, 98-110).
18. Estimated from results by Jeffrey et al. (Jeffrey, G. A.; Ruble, J. R.; McMullan, R. K.; Pople, J. A. The Crystal Structure of Deuterated Benzene. Proc. R. Soc. London 1987, A414, 47-57) (hexadeuteriobenzene at 15 K) and by Cox et al. (Cox, E. G.; Cruickshank, D. W. G.; Smith, J. A. S. The Crystal Structure of Benzene at -3 °C. Proc. R. Soc. London 1958, A247, 1-21) (benzene at 270 K). The value 0.68 in our compilation (Figure 5) is based on a study at 218 K by Bacon et al. (Bacon, G. E.; Curry, N. A.; Wilson, S. A. A Cristallographic Study of Solid Benzene by Neutron Diffraction. Proc. R. Soc. London 1964, A279, 98-110).
19. Piermarini, G. J.; Mighell, A. D.; Weir, C. E.; Bloch, S. Crystal Structure of Benzene H at 25 kilobars. Science 1969, 165, 1250-1255.
20. -1.
21. It has indeed been shown (Gavezzotti, A.; Filippini, G. Polymorphic Forms of Organic Crystals at Room Conditions: Thermodynamic and Structural Implications. J. Am. Chem. Soc. 1995, 117, 12299-12305) that, in polymorph pairs, the crystal with higher density mostly has a lower lattice vibrational entropy.
22. Despite the remarkable ice/water transition, we are not aware of a single organic compound that contracts on melting.
23. -1 at 300 K. See: Dunitz, J. D. The Entropic Cost of Bound Water in Crystals and Biomolecules. Science 1994, 264, 670.
24. As H. M. Powell pointed out many years ago (The Structure of Molecular Compounds. Part IV. Clathrate Compounds. J. Chem. Soc. 1948, 61-73) the formation of inclusion compounds is also possible even in the absence of attractive forces between host and guest. The guest molecule may simply be caught during crystal formation and held in an intermolecular cavity by repulsive forces: "...When this molecule approaches a possible hole of exit its outward passage will be opposed by the repulsive forces that arise when any two atoms approach closely...". Powell introduced the term "clathrate" compound to describe this situation, and it seems a pity that the term is often applied indiscriminately for inclusion compounds in general. Powell's emphasis on the importance of repulsive forces in mantaining crystal structures comes close to views expressed in this Account.
25. Pauling, L.; Delbrueck, M. The Nature of the Intermolecular Forces Operative in Biological Processes. Science 1940, 92, 77-79.
26. (a) van Eijck, B. P.; Spek, A. L.; Mooij, W. T. M.; Kroon, J. Hypothetical Crystal Structures of Benzene at O and 30 kbar. Acta Crystallogr. 1998, B54, 291-299.
27. (b) Gavezzotti, A. Polymorphism of 7-Dimethyl-armnocyclopenta[c]coumarin: Packing Analysis and Generation of Trial Crystal Structures. Acta Crystallogr. 1996, B52, 201-208.
28. Richardson, M. F.; Yang, Q.-C; Novotny-Bregger, E.; Dunitz, J. D. Conformational Polymorphism of Dimethyl-3,6-Dichloro-2,5-Dihydroxyterephtha-late. II. Structural, Thermodynamic, Kinetic and Mechanistic Aspects of Phase Transformations Among the Three Crystal Forms. Acta Crystallogr. 1990, B46, 653-660.
29. See also Stone, A. J.; Tsuzuki, S. Intermolecular Interactions in Strongly Polar Crystals with Layer Structures. J. Phys. Chem, 1997, B101, 10178-10183.
30. See for example: Israelachvili, J. Intermolecular and Surface Forces, 2nd ed.; Academic Press: New York, 1991; p 155 ff. Hobza, P.; Zahradnik, R. Intermolecular Complexes. The Role of van der Waals Systems in Physical Chemistry and in the Biodisciplines; Academia: Prague, 1988; p 215 ff. Gavezzotti, A. Molecular Aggregation of Acetic Acid in a Carbon Tetrachloride Solution: a Molecular Dynamics Study with a View to Crystal Nucleation. Chem. Eur. J. 1999, 5, 567-576 and references therein.
31. See for example: Israelachvili, J. Intermolecular and Surface Forces, 2nd ed.; Academic Press: New York, 1991; p 155 ff. Hobza, P.; Zahradnik, R. Intermolecular Complexes. The Role of van der Waals Systems in Physical Chemistry and in the Biodisciplines; Academia: Prague, 1988; p 215 ff. Gavezzotti, A. Molecular Aggregation of Acetic Acid in a Carbon Tetrachloride Solution: a Molecular Dynamics Study with a View to Crystal Nucleation. Chem. Eur. J. 1999, 5, 567-576 and references therein.
32. See for example: Israelachvili, J. Intermolecular and Surface Forces, 2nd ed.; Academic Press: New York, 1991; p 155 ff. Hobza, P.; Zahradnik, R. Intermolecular Complexes. The Role of van der Waals Systems in Physical Chemistry and in the Biodisciplines; Academia: Prague, 1988; p 215 ff. Gavezzotti, A. Molecular Aggregation of Acetic Acid in a Carbon Tetrachloride Solution: a Molecular Dynamics Study with a View to Crystal Nucleation. Chem. Eur. J. 1999, 5, 567-576 and references therein.
33. Mathews, C. K.; Baba, M. S.; Narasimham, T. S. L.; Balasubramanian, R.; Sivaraman, N.; Srinivasan, T. G.; Rao, P. R. V. Vaporization Studies of Buckminsterfullerene. J. Phys. Chem. 1992, 96, 3566-3568.
34. A formal proof that the hexagonal and cubic close packing of spheres is more dense than any irregular, i.e., nonperiodic, packing has been achieved only recently by Wu-yi Hsiang (Sphere Packings and Spherical Geometry - Kepler's Conjecture and Beyond; Center of Pure and Applied Mathematics, University of California: Berkeley, 1991). An extended discussion of the problem can be found in an article by N. Max (Nature 1992, 355, 115-116). Added in proof: But see Sloane, N. J. A. Kepler's Conjecture Confirmed. Nature 1998, 395, 435-436 for recent criticism of Hsiang's proof and description of a new proof by T. C. Hales.
35. A formal proof that the hexagonal and cubic close packing of spheres is more dense than any irregular, i.e., nonperiodic, packing has been achieved only recently by Wu-yi Hsiang (Sphere Packings and Spherical Geometry - Kepler's Conjecture and Beyond; Center of Pure and Applied Mathematics, University of California: Berkeley, 1991). An extended discussion of the problem can be found in an article by N. Max (Nature 1992, 355, 115-116). Added in proof: But see Sloane, N. J. A. Kepler's Conjecture Confirmed. Nature 1998, 395, 435-436 for recent criticism of Hsiang's proof and description of a new proof by T. C. Hales.
36. A formal proof that the hexagonal and cubic close packing of spheres is more dense than any irregular, i.e., nonperiodic, packing has been achieved only recently by Wu-yi Hsiang (Sphere Packings and Spherical Geometry - Kepler's Conjecture and Beyond; Center of Pure and Applied Mathematics, University of California: Berkeley, 1991). An extended discussion of the problem can be found in an article by N. Max (Nature 1992, 355, 115-116). Added in proof: But see Sloane, N. J. A. Kepler's Conjecture Confirmed. Nature 1998, 395, 435-436 for recent criticism of Hsiang's proof and description of a new proof by T. C. Hales.
37. Macgillavry, C. H. Symmetry Aspects of M. C. Escher's Periodic Drawings; A. Oosthoeks Uitgeversmaatschappij N.V.: Utrecht, The Netherlands, 1965.