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Revealing Germylene Compounds to Attain Superbasicity with Sigma Donor Substituents: A Density Functional Theory Study
Author(s) -
Biswas Abul Kalam,
Ganguly Bishwajit
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201605209
Subject(s) - electronegativity , chemistry , proton affinity , electron affinity (data page) , density functional theory , ionization energy , singlet state , lone pair , crystallography , binding energy , lewis acids and bases , computational chemistry , stereochemistry , ionization , molecule , atomic physics , ion , excited state , organic chemistry , physics , protonation , catalysis
Abstract Compounds of Ge II are shown for the first time to function as superbases. Two B(N=P i Pr 3 ) 2 groups attached to a germanium(II) center show a gas‐phase proton affinity of 296.2 kcal mol −1 , which is close to the range of a hyperbase as revealed by B3LYP‐D3/6‐31G(2d,p) level of theory. These DFT calculations showed better agreement of geometrical parameters for the reported stable germylene compound 1 than previously reported calculations. A systematic study with different substitutions of Ge II revealed that such a system can achieve basicity close to a hyperbase. The stabilities of these superbases were examined with dimerization energy and singlet–triplet state energy difference (Δ E S–T ). Furthermore, the calculated gas‐phase proton affinity values also show good correlation with the most negative valued point ( V min ) in electron‐rich regions from the molecular electrostatic potential. The high PA values of compounds were also supported by ionization potential, electron affinity, absolute electronegativity, and absolute hardness calculations. The energetics for the reaction with BH 3 and AlMe 3 further suggest that the lone pair of Ge II can act as a Lewis base and display higher donor–acceptor bond strengths.