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 calculated electronegativity and hardness of the SnRR'X groups, applying a methodology previously developed by Geerlings and coworkers (J. Phys. Chem. 1993, 97, 1826). These calculations allowed to see the regularities concerning the influence of the nature of organic groups RR' and inorganic group X on electronegativities and hardness of the SnRR'X groups; in this case, it was found a very good correlation between the electronegativity of the fragment and experimental 119 Sn chemical shifts, a property that sensitively reflects the change in the valence electronic structure of molecules. This work was complemented with the study of some compounds of the EX and ER types, where E= C, Si, Ge, Sn and R= CH 3 , H, which was performed to study the influence that the central atom has on the electronegativity and hardness of molecules, or whether these properties are mainly affected for the type of ligand bound to the central atom. All these calculations were performed using the B3PW91 functional together with the 6-311++G** basis set level for H, C, Si, Ge, F, Cl and Br atoms and the 3-21G for Sn and I atoms.

A new method to derive electronegativity from resonant inelastic x-ray scattering

“…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.…”

Pyrrolothiazolones as Potential Inhibitors for the nsP2B‐nsP3 Protease of Dengue Virus and Their Mechanism of Synthesis

“…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 .…”

“…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.…”

Synthesis and Catalytic Activity of Atrane‐type Hard and Soft Lewis Superacids with a Silyl, Germyl, or Stannyl Cationic Center

“…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).…”