Predicting novel strong acids of plumbylene at theoretical levels

Abstract

AbstractWe have reached at new acyclic plumbylenes which show high acidity, via B3LYP, Def2‐TZVP, MP2, and wB97XD functionals. Our scrutinized plumbylenes include dicyclopropaplumbylene (1), dicyclopentaplumbylene (2), dicycloheptaplumbylene (3), and their unsaturated analogs (1’‐3’, respectively). All scrutinized plumbylenes and their corresponding protonated forms, 1H(1’H)‐3H(3’H), appear as minima on their energy surfaces. The conductor‐like polarizable continuum model (CPCM) and integral equation formalism polarized continuum model (IEFPCM) are used to predict the pka values for electrophilic plumbylenes, 1(1’)‐3(3’), in chloroform and water. In most cases, plumbylenes turn out as strong acids for showing relatively high negative pka values. The acidity trend of plumbylenes (pka) appears consistent with their proton affinity (PA), electrophilicity (ω), nucleophilicity (N), Mulliken electronegativity ( ), absolute chemical hardness (ηabs), singlet‐triplet energy gap (ΔEs‐t), and highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gap (ΔEH‐L). Structure 1, with two cyclopropyl groups, turns out as the most acidic specie in chloroform and water.