M©B7O7+ (M = Ni, Pd, Pt): aromatic molecular stars with a planar heptacoordinate transition metal.

The dynamically stable global minima M©B7O7+ (M = Ni, Pd, Pt) are interesting in that they possess σ-aromaticity alone within the B7M core moiety, which can be attributed to the strong peripheral localized O → B π back-bonding that leads to the less favourable delocalized M → B π back-bonding over the B7M core moiety.