The 9-barbaralyl cation, 1,4-bishomotropylium ion and some related C9H9+ carbocations

The 9-barbaralyl and related C9H9+ carbocations — A QTAIM-DI-VISAB computational study

QTAIM-DI-VISAB analyses were used to characterize the bonding of the 9-barbaralyl cation, related C9H9+ cations, and rearrangement transition states. These analyses involved obtaining quantum theory of an atom in a molecule (QTAIM) molecular graphs and delocalization indexes (DIs) that were correlated with visualization of the proximities of atomic basins (VISAB). This study provides new insights into the bonding of these species and cements the QTAIM-DI-VISAB analysis as a method of choice for establishing the nature of the bonding in so-called nonclassical carbocations, while obviating the need for dashed-line representations of bonding.