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Context: Why are the halonium cations so effective in forming strongly-bound complexes? We directed our research to address this question and we present electrostatic potential data for the valence-state halogen atoms X and halonium cations X + , where X = Cl, Br, I. The electron densities and electrostatic potentials of the halonium cations show considerably greater anisotropy than do the valence state halogens. The distances from the electrostatic potential surface maxima to the halogen nuclei are about 0.5 Å smaller than the distances from the electrostatic potential surface minima to the nuclei, giving the halonium cations each a more disk-like shape than the corresponding neutral valence state halogens. Their surface electrostatic potentials are totally consistent with the directionalities of halonium cations in complexes and the strengths of their interactions. To add perspective to this brief report, we have included calculations of the isotropic cation K + and noble gas Kr., Methods: The calculations of the electrostatic potentials of the valence states of the halogen atoms Cl, Br and I and the halonium cations Cl + , Br + and I + , as well as K + and Kr, on 0.001 au contours of their electronic densities were carried out with Gaussian O9 and the Wave Function Analysis - Surface Analysis Suite (WFA-SAS) at the M06-2X/6-31 + G(d,p) and M06-2X/3-21G* levels., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A search has been conducted, by means of ab initio molecular orbital theory, for potential tetrel-bonded complexes formed between the fluorinated methanes methyl fluoride, difluoromethane and fluoroform, and the related hydrides ammonia, water, hydrogen fluoride, phosphine, hydrogen sulphide and hydrogen chloride. Eleven such complexes have been identified, six containing CH 3 F and five CH 2 F 2 . The complexes are typically less strongly bound than their hydrogen-bonded counterparts, and the interaction energies vary in a consistent way with the periodic trend of the electron donors. The intermolecular separations and changes of the relevant intramolecular bond lengths, the wavenumber shifts of the critical vibrational modes and the extents of charge transfer correlate, by and large, with the strengths of interaction., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The local and global reactivity descriptors of substituted dinitroaniline analogues were investigated using M06-2X/6-31 + G(d,p) method. It was observed that NH 2 (m = 3.53 eV; p = 3.70 eV) substituent conveyed the highest nucleophilic character on the benzene ring system than the other groups under study. For the substrates 4-substituted-1-chloro-2,6-dinitrobenzenes, the condensed to atom electrophilicity ([Formula: see text]) increases in the order COOCH 3  > NO 2  > F > SO 3 H > CN > Cl > Br. The para substituted groups with the halogens follow the order of increasing electronegativity, F > Cl > Br. However, the nucleophilicity of the halo substituents of the products increases in the order, F > Br > Cl. Molecular docking simulations using the homology model with the crystallographic structure of zinc-induced bovine tubulin heterodimer (1JFF) as one of the templates reveal that the interactions between the tubulins of Plasmodium falciparum and dinitroaniline analogues are due to H-bonding. In general, the binding interaction is with the following residues: Met137, ARG64, Lys60, Glu183, Val4, His28, Cys171, Tyr224, Asn206, 228, Ile235, and Leu238. The pK a s of the residue decrease as the ring activating power of the substituents increases from strongly activating to weakly activating groups. There is no evidence of intra or intermolecular H-bonding between Arg64 and Cys171. Electronegativity (χ) gives a better generic description of the dinitroanilines than any other parameters considered. Short-range hydrophobic interaction contributes to reduced binding affinities of the ligands. Graphical abstractReaction of substituted 2,6-dinitro chlorobenzene with diisopropylamine. Orbital interaction between the substrates and diisopropylamine in the formation of the dinitroanilines.

A number of properties of the homodimers of the three families of molecules MH 3 X, where M is Si, Ge, and Sn and X is F, Cl, Br, and I are computed. The results are compared with those of a similar study of the homodimers of the methyl halides containing the same four halogen atoms, and some notable differences are observed among related sets of monomer species. The interaction energies, the primary intermolecular geometrical parameters, the changes in the intramolecular bond lengths, and the vibrational data (wavenumber shifts and dimer/monomer infrared intensity ratios) of some of the modes most closely associated with the site of interaction show, for the most part, regular variations as the central atom and the halogen atom are systematically varied. The results are interpreted in terms of the changes in the bonding properties of the monomer molecules as they undergo dimerization. Graphical abstract Interaction energies of the silyl, germyl and stannyl fluoride, chloride, bromide and iodide dimers.

We present a systematic theoretical study on mono and digallium selenide clusters, Ga(m)Se(n) (m = 1, 2 and n  =  1-4), along with their negatively and positively charged counterparts. Different theoretical methods, namely density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2) and coupled cluster singles and doubles, including non-iterative triples [CCSD(T)], were employed in conjunction with the 6-311+G(2df) basis set. The lowest-energy configurations of gallium selenides prefer to be planar, with the exception of cationic GaSe4 and Ga2Se4. The adiabatic electron affinities (AEA) of Ga(m)Se(n) (m = 1, 2 and n  = 1-4) clusters range from 1.07 to 3.78 eV, and their adiabatic ionization potentials (AIP) vary from 7.57 to 8.76 eV using the CCSD(T)//B3LYP level of theory. It was found that the AEAs of gallium selenides do not depend solely on the electrophilicity of the clusters but also on their electronic structures. No significant trend was observed in the AIP values and HOMO-LUMO (H-L) gaps with increase in cluster size of the mono and digallium selenide series. Among the dissociation channels, the decomposition of GaSe4 → GaSe2 + Se2 was found to be thermodynamically most favored. Furthermore, the AEAs of GaSe2, GaSe3, GaSe4 and Ga2Se4 were found to exceed that of the chlorine atom and are therefore termed as 'superhalogens'. Finally, the AEAs of the Ga2X(n) (X = O-Se; n = 2-4) series were found to be almost similar.

Recent ab initio investigations of some complexes formed between carbon dioxide and its analogues carbonyl sulfide, carbonyl selenide, carbon disulfide, and thiocarbonyl selenide and the common bases ammonia, water, phosphine, and hydrogen sulfide have revealed significant differences between the properties of those complexes bound through the oxygen atom of the electron acceptor and their counterparts in which the interaction takes place through a sulfur atom. In each case the interaction is weak, but the structures, interaction energies, and vibrational spectra of the complexes show some regular variations in behavior as the base and the acid are systematically changed. The adducts bound through sulfur present examples of the type of non-covalent interaction known as the chalcogen bond. In this paper we extend the range of electron acceptors to include carbon diselenide, and we explore the effects of substituting selenium for sulfur as the acceptor atom in the complexes of OCSe, SCSe, and CSe2. These adducts are also classified as chalcogen-bonded complexes, and have many features in common with the sulfur-bonded species, but also exhibit some noticeable differences between the two series.

Quantum chemical calculations using density functional theory BP86/def2-TZVPP and ab initio methods at CCSD(T)/def2-TZVPP have been carried for the telluroketones H2A=Te (A = C, Si, Ge). DFT calculations have also been carried out for the ketones H2C=E (E = O, S, Se, Te) and for the complexes NHC → [H2A=Te] → B(C6F5)3. The nature of the bonding has been investigated with charge- and energy decomposition analyses. The calculated bond dissociation energies for the double bonds of the H2C = E and H2A = Te molecules show the expected trends O > S > Se > Te for atom E and C > Si > Ge for atom A. Complexation of the telluroketones in NHC → [H2A = Te] → B(C6F5)3 leads to longer and weaker A-Te bonds which exhibit the surprising trend for the bond dissociation energy Si > Ge > C. The contribution of the π bonding in H2A = Te increases for the heavier atoms with the sequence C < Si < Ge.

It is well-established that many covalently-bonded atoms of Groups IV-VII have directionally-specific regions of positive electrostatic potential (σ-holes) through which they can interact with negative sites. In the case of Group VII, this is called "halogen bonding." We have studied two series of molecules: the F3MX and, for comparison, the H3MX (M = C, Si and Ge; X = F, Cl, Br and I). Our objective was to determine how the interplay between M and X in each molecule affects the σ-holes of both, and consequently their interactions with the nitrogen lone pair of HCN. We find that the relative electronegativities of M and X are not sufficient to explain their effects upon each other's σ-holes; consideration of charge capacity/polarizability (and perhaps other factors) also appears to be necessary. However the results do support the description of normal σ-hole interactions as being largely electrostatically-driven.