Clustering of H2SO4 with BX3 (X=H, F, Cl, Br, CN,OH) compounds creates strong acids and superacids

Publication date: Available online 5 March 2019Source: Computational and Theoretical ChemistryAuthor(s): Younes Valadbeigi, Theo KurténAbstractThe interaction of H2SO4 with boron compounds including BH3, BF3, BCl3, BBr3, B(CN)3 and B(OH)3 was studied computationally using the ωB97xD density functional. All the BX3 compounds except B(OH)3 bind to H2SO4 via both SOH...X hydrogen bonds, and interactions between the B atoms and the S=O oxygen atoms. B(OH)3 interacts with H2SO4 solely through hydrogen bonds. B(CN)3 and BCl3 exhibit the strongest and weakest interactions with H2SO4, respectively. Natural bond orbital (NBO) analysis shows that the relative weakness of the H2SO4– BCl3 interaction may be due to π-bonding between the B and Cl atoms, and the occupation of the pz orbital of the B atom. The strong electron withdrawing groups CN in B(CN)3 intensify electron deficiency of B atom and promote its tendency to capture electrons of oxygen atom of O=S group. Atoms in molecules (AIM) calculations show bond critical points (BCP) between the X groups of BX3 and the hydrogen atoms of H2SO4 for all cases except X = OH. Enthalpies and Gibbs free energies of deprotonation in the gas phase (ΔHacid, ΔGacid) were calculated for (BX3)H2SO4 and (BX3)2H2SO4 complexes. These data revealed that clustering of BX3 with H2SO4 enhances the acidity of H2SO4 by about 9–58 kcal.mol-1. The (B(CN)3)2H2SO4 cluster had ΔHacid and ΔGacid values of 255.0 and 246.7 kcal.mol-1, respectively, and is...

Source: Computational and Theoretical Chemistry - March 6, 2019 Category: Chemistry Source Type: research