Evaluation of group electronegativities and hardness (softness) of group 14 elements and containing functional groups through density functional theory and correlation with NMR spectra data
Abstract:Quantum Chemical calculations for group 14 elements of Periodic Table (C, Si, Ge, Sn, Pb) and their functional groups have been carried out using Density Functional Theory (DFT) based reactivity descriptors such as group electronegativities, hardness and softness. DFT calculations were performed for a large series of tetracoordinated Sn compounds of the CH 3 SnRR'X type, where X is a halogen and R and R' are alkyl, halogenated alkyl, alkoxy, or alkyl thio groups. The results were interpreted in terms of calcul… Show more
“…The peculiar behavior of H follows from its unique chemistry, which arises due to its small size and lack of core electrons and because the EA for H is small due to the inability of the H orbital involved in a bond to expand as much as it does in free H − . 17 According to Bergmann and Hinze, 46 True et al 33 described three types of ligands: (1) hydrogen, with low electronegativity but high chemical hardness (6.4 eV/e), as defined by Parr and Pearson; 4,5 (2) the halogens, which have a range of electronegativities and chemical hardness (4.6 <η < 8.7), with the values roughly correlated to one another; and (3) a variety of other functional groups, including CF 3 and SF 5 , with chemical hardness between 2 and 3, uncorrelated to electronegativity. The high chemical hardness of H reflects its TABLE III.…”
Section: Comparison To Xps-derived Electronegativitiesmentioning
Electronegativity is a well-known property of atoms and substituent groups. Because there is no direct way to measure it, establishing a useful scale for electronegativity often entails correlating it to another chemical parameter; a wide variety of methods have been proposed over the past 80 years to do just that. This work reports a new approach that connects electronegativity to a spectroscopic parameter derived from resonant inelastic x-ray scattering. The new method is demonstrated using a series of chlorine-containing compounds, focusing on the Cl 2p(-1)LUMO(1) electronic states reached after Cl 1s → LUMO core excitation and subsequent KL radiative decay. Based on an electron-density analysis of the LUMOs, the relative weights of the Cl 2p(z) atomic orbital contributing to the Cl 2p(3/2) molecular spin-orbit components are shown to yield a linear electronegativity scale consistent with previous approaches.
“…The peculiar behavior of H follows from its unique chemistry, which arises due to its small size and lack of core electrons and because the EA for H is small due to the inability of the H orbital involved in a bond to expand as much as it does in free H − . 17 According to Bergmann and Hinze, 46 True et al 33 described three types of ligands: (1) hydrogen, with low electronegativity but high chemical hardness (6.4 eV/e), as defined by Parr and Pearson; 4,5 (2) the halogens, which have a range of electronegativities and chemical hardness (4.6 <η < 8.7), with the values roughly correlated to one another; and (3) a variety of other functional groups, including CF 3 and SF 5 , with chemical hardness between 2 and 3, uncorrelated to electronegativity. The high chemical hardness of H reflects its TABLE III.…”
Section: Comparison To Xps-derived Electronegativitiesmentioning
Electronegativity is a well-known property of atoms and substituent groups. Because there is no direct way to measure it, establishing a useful scale for electronegativity often entails correlating it to another chemical parameter; a wide variety of methods have been proposed over the past 80 years to do just that. This work reports a new approach that connects electronegativity to a spectroscopic parameter derived from resonant inelastic x-ray scattering. The new method is demonstrated using a series of chlorine-containing compounds, focusing on the Cl 2p(-1)LUMO(1) electronic states reached after Cl 1s → LUMO core excitation and subsequent KL radiative decay. Based on an electron-density analysis of the LUMOs, the relative weights of the Cl 2p(z) atomic orbital contributing to the Cl 2p(3/2) molecular spin-orbit components are shown to yield a linear electronegativity scale consistent with previous approaches.
“…The less hardness value and more softness value reveals that 209 has sufficient polarizability in the binding cavity of the receptor. The absolute electronegativity can be defined as the ability of the atom to attract electrons towards itself in a covalent bond . The electronegativity order of top four compounds is 159>190>209>205 .…”
Section: Resultsmentioning
confidence: 99%
“…The absolute electronegativity can be defined as the ability of the atom to attract electrons towards itself in a covalent bond. [45][46] The electronegativity order of top four compounds is 159 > 190 > 209 > 205. The global electrophilicity index can be defined as the ability of compounds to accept electrons from the surrounding environment.…”
Section: Dft Analysis Of Top Four Compoundsmentioning
Dengue fever is a severe disease in the present time. Based on literature, there is no effective approved medicine available in the market for the treatment of dengue fever. This fever is spreading rapidly and there is an urgency to find the potential and cost‐effective antiviral compounds for the development of medicine to cure the patients from dengue fever. Different computational and experimental approaches have been tried to find the potential inhibitors for the nsP2B‐nsP3 protease of dengue virus. In the present work, a four component one‐pot reaction was designed to get pyrrolothiazolones & its mechanism of synthesis was studied by density functional theory. A library based on pyrrolothiazolones was created using computational tools. Further, the designed compounds were docked to get the potent inhibitor aginst the nsP2B‐nsP3 protease of dengue virus. Further, different parameters like absorption, distribution, metabolism, excretion and toxicity were applied. DFT analysis of the hit compounds were performed using Gaussian 09. The molecular dynamics simulations study was performed to check the formation of complex between the screened compound and nsP2B‐nsP3 protease of dengue virus. Finally, the molecular mechanics‐Poisson Boltzmann surface area analysis was performed to determine the effective binding for the formation of complex of potent compound with the nsP2B‐nsP3 protease of dengue virus.
“…Notably, the rigid structures of 1 E + around the group 14 center given by the atrane framework help to activate the alkyne moiety of 8 without any deactivation by a strong interaction with the amide moiety. [ 1 Sn(CH 3 CN)][SbCl 6 ] exhibited the highest catalytic activity because of the softness of the Sn center in comparison to the Si and Ge centers [45] . Furthermore, all cations were further applicable to the cyclization reaction of the other alkyne 10 for the synthesis of isocoumarin 11 even though substrate 10 has an acidic proton (reaction D).…”
The synthesis and isolation of atrane‐type molecules 1E+ (E=Si, Ge, or Sn) having a cationic group 14 elemental center are reported. The cations 1E+ act as hard and soft Lewis superacids, which readily interact with various hard and soft Lewis basic substrates. The rigid atrane framework stabilizes the localized positive charge on the elemental center and assists the formation of the well‐defined highly coordinated states of 1E+. The cations were applied to the hydrodefluorination, Friedel‐Crafts reaction, alkyne cyclization, and carbonyl reduction as Lewis acid catalysts. Most notably, [1Si][ClO4] exhibits unique chemoselectivity that depends on a solvent in the competitive reaction of silyl enol ether with a mixture of benzaldehyde dimethyl acetal and benzaldehyde. Our findings indicate the potential of hard and soft Lewis superacids in organic synthesis.
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