Three dimensional aromaticity in pyramidanes C4R4E and Ge4R4Ge

Three dimensional aromaticity in pyramidanes C₄(SiMe₃)₄E (E = Ge, Sn, Pb, P⁺, BCl, Mg) and Ge₄(SiMe₃)₄Ge was investigated using gauge-included magnetically induced currents and electron density of delocalized bonds as two criteria. For the C₄(SiMe₃)₄E compounds, different series of the aromaticity degree have been obtained by the two methods, respectively: P > Ge ≥ Sn ∼ Pb > B and Pb ≥ Sn ≥ Ge > B > P. Two isomers of Ge₄(SiMe₃)₄Ge possess nearly equal aromaticity.