Quantifying the Inter- and Intramolecular Interactions in Crystalline Phthalic Acid

All inter- and intramolecular interactions
in the crystals of phthalic
acid have been quantified from the topology of the electron density
distribution obtained from low temperature (20 K) X-ray diffraction
data and from theoretical calculations. Using the Quantum Theory of
Atoms in Molecules (QTAIM) approach, all covalent bonds have been
characterized by the electronic properties at their (3, −1)
bond critical points as well as all noncovalent bonds of the type
O···H (both strong and weak), C···C,
O···O, O···C, and H···H.
Integrated atomic charges and the derived molecular dipole moment
are reported. Differentiation of the two faces of the pyramidalized
sp2 carbon atoms is investigated via the electrostatic
potential projected onto the molecular surface.