The electron localization function (ELF) has been separated in its sigma and pi components. topological analysis of the new ELFsigma ELFpi functions used to quantify concept resonance. highest bifurcation values these describe a correct way aromaticity classical ring molecules some aromatic compounds as B6CO6, Al4(2-), N5-. In case an important delocalization contribution found, which is agreement with previous interpretation.

An alternative response function, based on the dual descriptor in terms of Koopmans' approximation, is hereby proposed for description chemical reactivity systems with (quasi-) degenerate frontier molecular orbitals. This constructed from Fukui functions that include contributions different orbitals, i.e., orbital-weighted functions. The methodology applied to three case studies: first consists a series benchmark organic and inorganic molecules which descriptor, only not appropriate describe...

The prediction of reactivity is one the long‐standing objectives chemistry, contributing to enforce link between theory and experiment. In particular, regioselectivity aromatic molecules has motivated proposal different descriptors based on foundational theories, like Frontier Molecular Orbital (FMO) density functional theory, predict rationalize such regioselectivity. This article examines cases where descriptors, FMO are known have failed, specifically electrophilic substitution reactions,...

Abstract Herein, the first global minima containing a planar hexacoordinate carbon (phC) atom are reported. The fifteen structures belong to CE 3 M + (E=S–Te and M=Li–Cs) series satisfy both geometric electronic criteria be considered as true phC. design strategy consisted of replacing oxygen in D 3h CO Li structure with heavy less electronegative chalcogens, inducing negative charge on C an attractive electrostatic interaction between alkali‐metal cations. chemical bonding analyses indicate...

The quest for planar hypercoordinate atoms (phA) beyond six has predominantly focused on transition metals, with dodecacoordination being the highest reported thus far. Extending this bonding scenario to main-group elements, which typically lack d orbitals despite their larger atomic radius, posed significant challenges. Intrigued by potentiality of covalent formation using heavier alkaline-earth metals (Ae = Ca, Sr, Ba), so-called "honorary metals", we aim push boundaries hypercoordination....

This work deals with exploring some empirical scales of nucleophilicity. We have started evaluating the experimental indices nucleophilicity proposed by Legon and Millen on basis measure force constants derived from vibrational frequencies using a probe dipole H-X (X = F,CN). The correlation among theoretical parameters this scale has been evaluated. chosen as minimum electrostatic potential V(min), binding energy (BE) between nucleophile dipole, measured at position hydrogen atom V(H) when...

In this work an alternative to the analysis of Fukui function will be presented and compared with traditional condensed function. The topological allows us define basins corresponding different regions space, numerical integration density over those volumes gives a number amenable chemical interpretation in line applications. Various examples are shown, series small molecules, couple clusters, aromatic molecules. They discussed comparison other methodologies experimental evidence.

Non-peptidic thrombin inhibitors (TIs; 177 compounds) with diverse groups at motifs P1 (such as oxyguanidine, amidinohydrazone, amidine, amidinopiperidine), P2 cyanofluorophenylacetamide, 2-(2-chloro-6-fluorophenyl)acetamide), and P3 phenylethyl, arylsulfonate groups) were studied using molecular modeling to analyze their interactions S1, S2, S3 subsites of the binding site. Firstly, a protocol combining docking three dimensional quantitative structure–activity relationship was performed. We...

Although aromaticity is a concept in chemistry, the last years, special efforts have been carried out order to propose theoretical strategies quantify it as property of molecular rings. Among them, perhaps computation nucleus independent chemical shifts (NICSs) most commonly used, since possible calculate an easy and fast way with used quantum chemistry software. However, contradicting assignments by NICS other methods reported literature, especially studies concerning inorganic chemistry....

A novel program for the search of global minimum structures atomic clusters and molecules in gas phase, AUTOMATON, is introduced this work. This involves following: first, generation an initial population, using a simplified probabilistic cellular automaton method, which allows easy control adequate distribution atoms space; second, fittest individuals are selected to evolve, through genetic operations (mating mutations), until best candidate surfaces. In addition, we propose simple way...

The aromaticity of benzene, Al42- cluster, cyclopropane, borazine and planar cyclooctatetraene (COT) was analyzed according to different strategies based on nucleus-independent chemical shift (NICS) computations. analysis NICS-components evolution along the main molecular axis seems be most adequate simplest strategy predict aromatic or antiaromatic character studied systems. Moreover, σ- π-electron contributions out-of-plane component NICS (NICS zz ) leads same qualitative quantitative...

It was recently shown that, when tested in cellular systems, quercetin oxidized products (Qox) have significantly better antioxidant activity than (Q) itself. The main Qox identified the experiments are either 2,5,7,3′,4′-pentahydroxy-3,4-flavandione (Fl) or its tautomer, 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (Bf). We now performed a theoretical evaluation of different physicochemical properties using density functional theory (DFT) calculations on Q and species. most...

We report a comprehensive assessment of Lewis acidity for series carbone-stibenium and -bismuthenium ions using the Gutmann-Beckett (GB) method. These new antimony bismuth cations have been synthesized by halide abstractions from (CDC)PnBr3 [(pyCDC)PnBr2][Br] (CDC = carbodicarbene; Pn Sb or Bi; py pyridyl). The reaction (CDC)SbBr3 (1) with one two equivalents AgNTf2 (NTf2 bis(trifluoromethanesulfonyl)imide) AgSbF6 gives stibaalkene mono- dications form [(CDC)SbBr3-n][A]n (2-4; n 1,2; A NTf2...

The presence of a delocalized π-bond is often considered an essential criterion for achieving planar hypercoordination. Herein, we show that σ-delocalization could be sufficient to make the configuration most stable isomer in series pentacoordinate s-block metals. High-level ab initio computations reveal global minimum interalkali and interalkali-alkaline earth clusters (LiNa5, Li5Mg+, Na5Mg+, K5Ca+, CaRb5+, Rb5Sr+, SrCs5+) adopts singlet D5h structure with lithium or alkaline metal (AE =...

We have explored in detail the potential energy surfaces of Si(5)Li(n)(5-6) (n = 5-7) systems. found that it is feasible to design three-dimensional star-like silicon structures using appropriate ligands. The global minimum structure for Si(5)Li(7)(+) has a perfect seven-peak structure. title compounds comprise, essentially, Si(5)(6-) ring interacting with lithium cations. ionic character Si-Li interactions induces formation bridged Concomitantly, our calculations show reduction Pauli...

We performed global minimum searches for the B(n) H(n+2) (n=2-5) series and found that classical structures composed of 2c-2e B-H B-B bonds become progressively less stable along series. Relative energies increase from 2.9 kcal mol(-1) in B(2) H(4) to 62.3 B(5) H(7). believe this occurs because boron atoms studied molecules are trying avoid sp(2) hybridization trigonal structure at atoms, as case one 2p-AO is empty, which highly unfavorable. This affinity have some electron density on all...

In the course of a reaction it is shape Fukui potential that guides distant reagent toward site where an electrophile/nucleophile willing to accept/donate charge. this paper we explore mathematical characteristics and demonstrate its relationship hardness ability atom in molecule change The not only determines active for electron transfer, but also approximates distribution molecule: Coulomb contribution frontier local hardness. at position nuclei equal variation chemical with nuclear charge...

The most stable forms of E(5)Li(7)(+) (E = Ge, Sn, and Pb) have been explored by means a stochastic search their potential-energy surfaces using the gradient embedded genetic algorithm (GEGA). preferred isomer Ge(5)Li(7)(+) ion is slightly distorted analogue D(5h) three-dimensional seven-pointed starlike structure adopted lighter C(5)Li(7)(+) Si(5)Li(7)(+) clusters. In contrast, structures for Sn(5)Li(7)(+) Pb(5)Li(7)(+) are quite different. By starting from arrangement, corresponding...

A new approach to stabilize compounds containing a planar tetracoordinate carbon (ptC), embedded in aromatic hydrocarbons, is presented herein.

The pandemic that started in Wuhan (China) 2019 has caused a large number of deaths, and infected people around the world due to absence effective therapy against coronavirus 2 severe acute respiratory syndrome (SARS-CoV-2). Viral maturation requires activity main viral protease (M

Here, we analyze the possibility of predicting local and global current densities in a series bicyclic hydrocarbons with 4n + 2 π-electrons from nucleus-independent chemical shifts (NICS) computations.

Four different ways to condense the Fukui function are compared. Three of them perform a numerical integration over basins define condensed function, and other one is most traditional using Mulliken population analysis. The chosen be electron density (AIM), localization (ELF), itself. use last two new presented for first time here. It found that three methods yield results which stable against change in basis set. ELF not able give information on reactivity an acceptor molecule. In general,...

In this article, we employed the induced magnetic field method to show that Al2X6 (X = F, Cl, Br, I) clusters cannot be classified as aromatic systems. Interestingly, even nucleus independent chemical shift (NICS) reveals same conclusion when analyzed in greater detail, showing a superficial analysis of index can easily lead incorrect interpretations. view fact NICS is extensively used by computational and theoretically oriented experimental chemists, an important warning against analyses,...

The B19− anion and other boron species have been dubbed 'Wankel motors' for the almost barrierless rotation of inner outer concentric rings relative to each in these compounds. A single substitution is shown shut down well-established fluxionality anion. carbon atom substituted structure give a neutral CB18 computationally enforce bond localization.