Concurrent loss of aromaticity and onset of superexchange in Mg3Na2 with an increasing Na–Mg3 distance

Gradual migration of Na+ from Mg32− brings about fascinating change in aromatic and magnetic behavior of inorganic Mg3Na2 cluster, which is addressed at the B3LYP and QCISD levels. During this process, Na+ takes away the electron density from Mg32− causing a net decrease in aromaticity. A tug-of-war between the Pauli repulsion and the aromaticity is shown to be responsible for the observed stability and aromaticity trends in singlet and triplet states. Implications of a spin crossover vis-a-vis a possible superexchange are also explored.