σ-Aromaticity Planar Pentacoordinate Beryllium Atoms

Six-valence-electron planar pentacoordinate beryllium (ppBe) is explored herein as a global minimum, which is only constructed by s-block metals in BeM5+ (M = Cu, Ag, Au). The bonding in ppBe can be regarded as the excited-stated Be with a 2p(x)(1)2p(y)(1) electronic configuration, forming electron sharing with doublet M-5(+) motifs followed by two sets of Be(p(parallel to)) ->[M-5(+)] sigma donations and one Be(s) <-[M-5(+)] sigma back-donation. Thus, the sigma aromaticity originating from three delocalized s orbitals gives rise to the whole stability of the high D-5h-symmetry ppBe and strongly enriches s-block planar hypercoordinate bonding.

Automated summary

The study explores the stability of planar pentacoordinate beryllium with six valence electrons, which is only constructed by s-block metals in BeM5+ (M = Cu, Ag, Au). The bonding in ppBe can be regarded as a result of sigma aromaticity originating from three delocalized s orbitals and electron sharing with doublet M-5(+) motifs.