Experimental and theoretical investigation on binary anionic clusters of Al(m)Bi(n)(-).

Al(m)Bi(n)(-) (m = 1-12; n = 1-4) binary cluster anions are generated by laser ablation of a sample composed of Al and Bi, and studied by reflectron time-of-flight mass spectrometry (RTOF-MS) in the gas phase. Some clusters with magic numbers are present in the mass spectrum. The structures of Al(m)Bi(n)(-) (m + n <or=7) clusters are investigated with the density functional theory (DFT) method and the most likely structures are obtained. The calculations of the binding energy (BE), energy gain (Delta) and HOMO-LUMO gaps confirm that the Al(2)Bi(3)(-) cluster has a very stable structure, which agrees well with the experimental results. It is further established that Al(2)Bi(3)(-) can be considered as a gas-phase Zintl analogue that follows Wade's rules and is the analogue of Ga(2)Bi(3)(-) and Sn(5)(2-) Zintl ions.