Protonation of Borylated Carboxonium Derivative [2,6-B10 H8 O2 CCH3 ]−: Theoretical and Experimental Investigation

Abstract

The process of protonation of [2,6-B10 H8 O2 CCH3 ]− was investigated both theoretically and experimentally. The most suitable conditions for protonation of the derivative [2,6-B10 H8 O2 CCH3 ]− were found. The process of protonation was carried out in the presence of an excess of trifluo-romethanesulfonic acid CF3 SO3 H at room temperature in dichloromethane solution. The structure of the resulting complex [2,6-B10 H8 O2 CCH3 *Hfac ]0 was established using NMR data and the results of DFT calculations. An additional proton atom Hfac was found to be localized on one of the facets that was opposite the boron atom in a substituted position, and which bonded mainly with one apical boron atom. The main descriptors of the B-Hfac bond were established theoretically using QTAIM and NBO approaches. In addition, the mechanism of [2,6-B10 H8 O2 CCH3 ]− protonation was investigated.