Revealing Germylene Compounds to Attain Superbasicity with Sigma Donor Substituents: A Density Functional Theory Study

Abstract

Compounds of Ge are shown for the first time to function as superbases. Two B(N=PiPr ) groups attached to a germanium(II) center show a gas-phase proton affinity of 296.2 kcal mol , 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 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 (ΔE ). Furthermore, the calculated gas-phase proton affinity values also show good correlation with the most negative valued point (V ) 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 and AlMe further suggest that the lone pair of Ge can act as a Lewis base and display higher donor-acceptor bond strengths.

Exploiting the (–C–H···C–) Interaction to Design Cage-Functionalized Organic Superbases and Hyperbases: A Computational Study

“…The superbase calculations with a variety of systems are performed with the B3LYP DFT functional, hence this functional was used for the study. 39 , 40 There are several reports where B3LYP-D3 were employed in calculating PAs, and a reasonable agreement was found between the experimental and computated PA values. 41 , 42 The presence of an intramolecular (–C–H···C–) interaction in the protonated P-MHPN helps in alleviating the steric strain in the unprotonated base.…”

“…In our study, the P-MHPN was optimized at M062 X /6-31G­(d) and B3LYP-D3/6-311+G­(d,p) levels, which have shown similarity with the available crystal structure. The superbase calculations with a variety of systems are performed with the B3LYP DFT functional, hence this functional was used for the study. , There are several reports where B3LYP-D3 were employed in calculating PAs, and a reasonable agreement was found between the experimental and computated PA values. , The presence of an intramolecular (–C–H···C–) interaction in the protonated P-MHPN helps in alleviating the steric strain in the unprotonated base. This naphthalene framework, which was employed to synthesize P-MHPN and anchored to P-ylide to generate the superbase, is similar to a class of nitrogen-based 1,8-bis­(dimethylamino)­naphthalene-type superbases, where the N–H···N hydrogen bonding plays a predominant role in achieving superbasicity. ,, Therefore, exploiting the possibility of intramolecular –C–H···C– interaction opens a new avenue for the design of neutral organic superbases.…”

Predicting novel strong acids of plumbylene at theoretical levels

“…The acid‐base theory has been scrutinized for many years. [ 1–4 ] The acidity and basicity of carbenes, [ 5–7 ] silylenes, [ 8–10 ] germylenes, [ 11,12 ] and stannylenes [ 13 ] have been studied at theoretical levels. In contrast, plumbylenes, especially their acyclic isomers, are less considered.…”

Design of Exceptional Strong Organosuperbases Based on Iminophosphorane and Azaphosphiridine Derivatives: Harnessing Ring Strain and Aromaticity to Engineer Neutral Superbases

“…Based on these factors, a wide variety of the superbase such as silylenes, germylenes, guanidines, imidazolines, guanidinophosphazenes, phosphorus ylides, amines, quinones, iminopolyenes, etc . have been reported in the scientific resources . Phosphazenes are a large family of the phosphorous superbases which have nowadays attracted much attention .…”

“…The gas phase proton affinity (PA) of HMPN was 12 times more than that of 1,8‐bis(dimethylamino)naphthalene (DMAN) as the first reported superbase . Several other structures containing the phosphazene groups such as Verkade bases, Germylene phosphazene and proazaphosphatranes have also been designed and examined their basicity (Scheme ).…”