Novel
thioureas RNHC(S)NHP(S)(OiPr)2 [R = (HOCH2)(Me)2C (1), Me2CH2CH2 (2), 2-CF3C6H4 (3), 2-Pym (4), and bis-thiourea
1,5-C10H6{NHC(S)NHP(S)(OiPr)2} (5)] have been synthesized and characterized by NMR,
X-ray diffraction, Hirshfeld surface analysis, and theoretical ETS-NOCV
charge and energy decomposition calculations. The monomers contain
multiple intramolecular noncovalent interactions including N–H···X
(X = O, 1–3; F, 3; N, 4; S, 5) and C–H···Y (Y
= O, 1; N, 2 and 3; S, 4 and 5) augmented further by homopolar C–H···H–C
contacts in all the structures. It has been determined that the three-dimensional
crystal networks are primarily constituted from intermolecular H···H
and H···S contacts due to homopolar C–H···H–C
as well as X–H···S (X = N, C) interactions.
They are, depending on the system, augmented further by C–H···Y
(Y = π, S, F) as well as by σ-hole(S)···π
interactions. ETS-NOCV allowed us to delineate that in the case of
C–H···H–C, C–H···Y,
and σ-hole(S)···π intermolecular interactions,
except for the electrostatically dominated N–H···N
in 4, London dispersion forces appeared to be a crucial
contributor to the stability with non-negligible factors stemming
from electrostatics and charge delocalization terms. Remarkably, the
dispersion dominated (∼50% of the overall stabilization ΔE
elstat + ΔE
orb + ΔE
dispersion) σ-hole(S)···π
interactions appeared to be the strongest among all the discovered
interactions, including classical hydrogen bonds N–H···N.
The electrostatic and charge delocalization contributions within the
σ-hole(S)···π interactions amount to ∼30%
and ∼20%, respectively.