Qualitative analysis of intermolecular interactions: Hirshfeld
surface and 2D fingerprint plots
Hirshfeld surface (HS) has widely been used as a qualitative tool to
analyze the intermolecular contacts present in the title complex. The
2D-fingerprint plots (2D-FP) were obtained for the individual component
of the complex from the HS analysis (Fig. 5). For the lysinium cation,
the intermolecular H···H interactions (with the contribution of 45.9%)
are appeared as a single spike
(d i+d e = 2.0 Å;d i and d e are the
distances from the surface to the nearest nucleus internal and external
to the surface, respectively) which confirms the existence of
C6–H6B···H14–C14 contact (motif D3). The next contribution comes from
the intermolecular H···O interactions and shown as double spikes with
the shortest d i+d edistance of 1.8 Å. It should be noted that the intermolecular H···C
contacts (sum of d i and d edistance is being 2.8 Å) are contributing 11% to the total HS area of
the cation. The entire contribution emanated from the donor molecules
(d e > d i) for
these interactions. The C=Olp···Cπcontacts contribute about 0.8% to the total HS area.
For mandelate anion, the H···H contacts are also shown as a single spike
on the FP with the shortest contact at 2.0 Å. In the case of H···O
contacts, there is a remarkable difference noticed on the FP as compared
to the lysinium ion. The contribution from donor molecules
(d e > d i) is
reduced by ca . 2.5% that of the acceptor molecules
(d e < d i) of the
anion. Similarly, the acceptor molecules contributing more to the H···C
contacts from the anion as compared to the cation in which the
contribution of donor molecules is more towards crystal packing.
Furthermore, the contributions of H···H and H···O also varied between
water molecules.