Geometry and bonding of small binary boron-aluminum clusters BnAln (n=1-7): Electron donation and interlocking aromaticity

© 2018 Elsevier B.V. Binary B n Al n clusters (n = 1-7) were investigated using both DFT/TPSSh and G4 calculations. B and Al atoms do not mix together but prefer to be assembled in two separated but interacting B n and Al n components. Large electron donation from Al to B atoms induces a donor-acceptor stabilization. Planar B 3 Al 3 is a σ aromatic compound. B 4 Al 4 exhibits two aromatic electron flows that are interlocking in two perpendicular planes and circulate independently. The B 7 Al 7 cluster appears as a double layer structure and this suggests formation of B n and Al n layers in larger clusters connected by electrostatic interactions.