150
S. Tsuzuki
crystal. Therefore, the water crystal has large vacant space, which is not advantageous
for the stabilization by the dispersion interactions.
On the other hand, the crystal structure in which the vacant space is reduced and the
average intermolecular distance is shortened like the benzene crystal in Fig. 8.10b is
advantageous for the stabilization of the crystal, if the major source of the attraction
between adjacent molecules in the crystal is the dispersion interactions. Most of
organic crystals have structures which have few vacant spaces. This result suggests
that the dispersion interactions are the primary source of attraction in most of organic
crystals.
8.10 Summary
Ab initio molecular orbital calculations and dispersion-corrected DFT calculations
are becoming powerful methods for studying intermolecular interactions in organic
crystals. We can obtain detailed information on the intermolecular interactions in
crystals (magnitude and origin of attraction). The intermolecular interactions in
crystals have been mainly discussed based on the presence or absence of atom–
atom contact at short distances. However, analysis of intermolecular interactions in
organic crystals show that the strong attraction by the dispersion interactions often
exists between adjacent molecules in crystals, even if adjacent molecules do not have
short atom–atom contact. The analysis shows that we should remember the significant importance of the dispersion interactions in organic crystals and the danger to
discuss the intermolecular interactions in crystals solely based on crystal structures.
The analysis of intermolecular interactions in crystals by theoretical calculations is
important for understanding structures and properties of organic crystals.
References
1. Tsuzuki, S., Orita, H., Sato, N.: Intermolecular interactions of oligothienoacenes: do S···S
interactions positively contribute to crystal structures of sulfur-containing aromatic molecules?
J. Chem. Phys. 145, 174503 (2016)
2. Stone, A.J.: The Theory of Intermolecular Forces, 2nd edn. Oxford University Press, Oxford
(2013)
3. Nishio, M., Hirota, M., Umezawa, Y.: The CH/π Interaction. Wiley-VCH, New York (1998)
4. Tsuzuki, S., Honda, K., Uchimaru, T., Mikami, M., Tanabe, K.: The magnitude of the
CH/π interaction between benzene and some model hydrocarbons. J. Am. Chem. Soc. 112,
3746–3753 (2000)
5. Tsuzuki, S., Fujii, A.: Nature and physical origin of CH/π interaction: significant difference
from conventional hydrogen bonds. Phys. Chem. Chem. Phys. 10, 2584–2594 (2008)
6. Desiraju, G.R., Steiner, T.: The Weak Hydrogen Bond (Oxford University Press, New York,
1999)
7. Tsuzuki, S., Mikami, M., Yamada, S.: Origin of attraction, magnitude, and directionality of
interactions in benzene complexes with pyridinium cations. J. Am. Chem. Soc. 129, 8656–8662
(2007)
S. Tsuzuki
crystal. Therefore, the water crystal has large vacant space, which is not advantageous
for the stabilization by the dispersion interactions.
On the other hand, the crystal structure in which the vacant space is reduced and the
average intermolecular distance is shortened like the benzene crystal in Fig. 8.10b is
advantageous for the stabilization of the crystal, if the major source of the attraction
between adjacent molecules in the crystal is the dispersion interactions. Most of
organic crystals have structures which have few vacant spaces. This result suggests
that the dispersion interactions are the primary source of attraction in most of organic
crystals.
8.10 Summary
Ab initio molecular orbital calculations and dispersion-corrected DFT calculations
are becoming powerful methods for studying intermolecular interactions in organic
crystals. We can obtain detailed information on the intermolecular interactions in
crystals (magnitude and origin of attraction). The intermolecular interactions in
crystals have been mainly discussed based on the presence or absence of atom–
atom contact at short distances. However, analysis of intermolecular interactions in
organic crystals show that the strong attraction by the dispersion interactions often
exists between adjacent molecules in crystals, even if adjacent molecules do not have
short atom–atom contact. The analysis shows that we should remember the significant importance of the dispersion interactions in organic crystals and the danger to
discuss the intermolecular interactions in crystals solely based on crystal structures.
The analysis of intermolecular interactions in crystals by theoretical calculations is
important for understanding structures and properties of organic crystals.
References
1. Tsuzuki, S., Orita, H., Sato, N.: Intermolecular interactions of oligothienoacenes: do S···S
interactions positively contribute to crystal structures of sulfur-containing aromatic molecules?
J. Chem. Phys. 145, 174503 (2016)
2. Stone, A.J.: The Theory of Intermolecular Forces, 2nd edn. Oxford University Press, Oxford
(2013)
3. Nishio, M., Hirota, M., Umezawa, Y.: The CH/π Interaction. Wiley-VCH, New York (1998)
4. Tsuzuki, S., Honda, K., Uchimaru, T., Mikami, M., Tanabe, K.: The magnitude of the
CH/π interaction between benzene and some model hydrocarbons. J. Am. Chem. Soc. 112,
3746–3753 (2000)
5. Tsuzuki, S., Fujii, A.: Nature and physical origin of CH/π interaction: significant difference
from conventional hydrogen bonds. Phys. Chem. Chem. Phys. 10, 2584–2594 (2008)
6. Desiraju, G.R., Steiner, T.: The Weak Hydrogen Bond (Oxford University Press, New York,
1999)
7. Tsuzuki, S., Mikami, M., Yamada, S.: Origin of attraction, magnitude, and directionality of
interactions in benzene complexes with pyridinium cations. J. Am. Chem. Soc. 129, 8656–8662
(2007)