title: On the aromaticity of square planar Ga4(2-) and In4(2-) in gaseous NaGa4- and NaIn4- clusters.
abstract: We investigated the electronic structure and chemical bonding of two bimetallic clusters NaGa4- and NaIn4-. Photoelectron spectra of the anions were obtained and compared with ab initio calculations. We found that the ground state of the two anions contains a square planar dianion interacting with a Na+ cation. The Ga4(2-) and In4(2-) dianions both possess two delocalized pi electrons and are considered to be aromatic, similar to that recently found in Al4(2-). Using calculations for a model compound, we showed that a recently synthesized Ga4-organometallic compound also contains an aromatic -Ga4(2-)- unit, analogous to the gaseous clusters.
authors.affiliation: Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Kuznetsov
authors.forename: A I
authors.initials: AI
authors.lastname: Boldyrev
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: L S
authors.initials: LS
authors.lastname: Wang