Probing Weak Intermolecular Interactions by Using the Invariom Approach: A Comparative Study ofs‐Tetrazine

Abstract

A comparative study of chemical bonding peculiarities in 1,2,4,5-tetrazine was carried out to test the performance of a recently developed invariom approach against a conventional charge density analysis of high-resolution X-ray diffraction data and quantum chemical calculations within the plane-wave functional theory. The amazing similarity between the intermolecular features thus obtained for this van der Waals crystal showed the invariom approximation to now emerge as a fast and convenient way towards reliable description of weak intermolecular interactions.

A New Class of Homogeneous Visible‐Light Photocatalysts: Molecular Cerium Vanadium Oxide Clusters

“…The invariom approximation was found to better describe interionic interactions with the chloride anion than with the carbonate anion, although the electron density distribution of the former is governed by the crystal environment around it and that of the latter is well defined by covalent bonds within it. This, however, agrees with an excellent performance of the invariom approximation in the case of weaker contacts in molecular crystals 14…”

“…The largest difference in the E int values for the H‐bonds obtained from the invariom and full multipole refinements for GuaCl is below 0.3 kcal mol −1 . The energy estimated for the anion ⋅⋅⋅ π interaction from the two models is even closer (0.6 vs. 0.7 kcal mol −1 ), as in the case of other cation–anion and cation–cation interactions; being weak, those are better described by the invariom approximation 14…”

“…In particular, the value of local potential energy v (r) in a bcp provides an estimate for the energy of an interaction ( E int );26, 27 a semi‐qualitative relation between these two parameters was initially observed for H‐bonds26, 27 and later successfully applied to other types of intermolecular and interionic interactions28 (it is also the best choice for estimating the energy of binding between ionic species, for which classical “energy difference‐based” approach in quantum chemistry predicts destabilizing character29). This methodology proved very helpful for revealing a good performance of the invariom approximation for molecular crystals, with a sum of the interaction energies thus estimated quite nicely reproducing the energy of a crystal lattice 14…”

Experimental Charge Density Evidence for Pnicogen Bonding in a Crystal of Ammonium Chloride

“…[30,31] With a very simple form as 0.5v(r), it was repeatedly shown to give accurate estimates in many cases (those are succinctly summarized in Ref. [32]), including weak interactions, such as H···H and CÀH···O [57] or CÀH···N, [58] Mg···C, and Ca···C interactions, [59,60] strong and intermediate hydrogen bonds, [61] CaÀO(carbonate), [62] AuÀPPh 3 , and GdÀOH 2 bonds, [63,64] etc. [32] The interaction energies thus obtained were shown to accurately reproduce the energy of a crystal lattice, [57,58,62,65,66] the discrepancy between the crystal lattice energies estimated in such a manner from X-ray diffraction data and those measured experimentally can be as small as 0.2 kcal mol À1 .…”

“…[32]), including weak interactions, such as H···H and CÀH···O [57] or CÀH···N, [58] Mg···C, and Ca···C interactions, [59,60] strong and intermediate hydrogen bonds, [61] CaÀO(carbonate), [62] AuÀPPh 3 , and GdÀOH 2 bonds, [63,64] etc. [32] The interaction energies thus obtained were shown to accurately reproduce the energy of a crystal lattice, [57,58,62,65,66] the discrepancy between the crystal lattice energies estimated in such a manner from X-ray diffraction data and those measured experimentally can be as small as 0.2 kcal mol À1 . [57,67] PW-DFT calculations were carried out by using the VASP 5.3.3 program; [68][69][70][71] exchange and correlation parts of the total energy were described by means of PBE functional.…”