First report of a planar and a quasi-planar Al13+ cluster having localized antiaromatic deltas within an aromatic sea: NICS, ELF, AIM, and AdNDP bonding analysis.

A perfectly planar Al13+ cluster (CI) and a quasi-planar Al13+ cluster (CII) have been found for the first time. Both clusters have a triangular core surrounded by a set of ten Al atoms in the form of a ring. These cationic clusters have substantial aromatic character. The planar CI cluster has local antiaromatic patches within global aromatic sea. It is doubly aromatic having both σ and π aromatic character. The quasi-planar CII cluster is also aromatic but it has more σ-delocalization. Graphical abstract Planar and quasi-planar Al13+ clusters with triangular core surrounded by a ring of ten atoms.