Electronic structure of semiconductor clusters and the special stability of – A gas phase Zintl analogue

Here we present evidence that the gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO gap) can be tuned (1.12–1.89 eV) by changing the Ga composition of Bi3Gay anionic and neutral clusters, some of which display special stability. Collaboratively, mass spectrometry, photoelectron spectroscopy and computational results show that Bi 3 Ga 2 - is a very stable cluster with a large calculated HOMO–LUMO gap of 1.89 eV, and can be viewed as a gas phase Zintl analogue of Sn 5 2 - , already synthesized in the solution phase. The stability of Bi 3 Ga 2 - is further attributed to the fact that it has 12 valence electrons and possesses a closo structure in agreement with Wade’s rules.