Could more than two atoms be bound in such a way that a π-bond is the major bonding force without involving σ-bond at all? To answer this question, we have shown that 3, 4 or 5 metal atoms can be held together by a single π-bond in the Mg 3 - , NaMg 3 - and Na 2 Mg 3 species. In both the NaMg 3 - and Na 2 Mg 3 species, the basic structural unit is an unusual Mg 3 2 - trigonal planar cluster, which exhibits properties of aromaticity, because it satisfies the 4n+2 rule for π-electrons and it is an equilateral triangle. Natural population analysis shows that the Na atomic orbitals contribute to formation of the π-bonding MO and thus all four in NaMg 3 - or all five in Na 2 Mg 3 atoms are involved in chemical bonding. In these clusters, π-aromaticity occurs without initial formation of the σ-framework.