ELF basin centroids (magenta) for dication
 
Normal modes for neutral triplet
 
Normal modes for 6coordinate boron cation
 
Normal modes for 6coordinate nitrogen trication
 

 An ELF basin analysis for this dication^{[1]} based on a b3lyp/6311g(d,p) calculation^{[2]} has been reported ^{[3]} as revealing five basal carbon to apical carbon basins of 0.75e and a regular disynaptic apicalCH basin, thus supporting hexacoordination. QTAIM analysis indicated that value of ρ(r) for the bond critical point located for each of the five apical CC bonds is 0.156 au. The NBO Wiberg bond index at the 6coordinate carbon is 3.9588, which indicates it is not hypervalent. See also Pentacoordinated_Carbon.
 An obvious question to ask is what happens to this dication if two electrons are added to create a neutral species.^{[4]} In fact the lowest unoccupied orbital has degenerate Esymmetry, and so the spin state of such a neutral species would have to be a triplet to preserve symmetry and avoid JahnTeller distortion. This species is a higherorder stationary point, with TWO sets of degenerate normal modes (E2, E1) associated with negative force constants. You can inspect this and other modes by rightclicking in the JSmol window on the left and selecting model from the popup window that appears (third menu down from top).
 The isoelectronic B^{1+} and N^{3+} sixcoordinate cations are shown to the left. The first is a stable minimum^{[5]}, but the second has four low frequency imaginary modes indicating it is not a minimum.^{[6]} The neutral isoelectronic Be system is also stable.^{[7]}
