Study on electronic structures and properties of neutral and charged arsenic sulfides [As n S3 ((-1,0,+1)), n =1-6] with the Gaussian-3 scheme.

The structures and energies of neutral and charged arsenic sulfides As n S3 ((-1,0,+1)) (n = 1-6) were studied systematically with the G3 method. The ground-state structures of these species are reported. The ground-state structures of As n S3 with n ≥ 4 can be considered as resulting from the replacement of an As atom of the ground-state structure of neutral As n+1S2 by an S atom. In neutral As n S3, the character of sulfur bonding is edge-bridging. The ground-state structures of anion As n S3 (-) sometimes differ from their corresponding neutral structures. In such case, they exhibit a terminal sulfur atom. The ground-state structures of cationic As n S3 (+) are also sometimes different from the corresponding neutral ones. There, sulfur bonding can exhibit face-capping and arsenic can be four-fold coordinated. The potential energy surfaces of As4S3 (+) and As5S3 (+) are very flat and co-existence of various isomers of As4S3 (+) and As5S3 (+) is possible. Reliable adiabatic electron affinities (AEAs) and adiabatic ionization potentials (AIPs) of As n S3 are predicted. There are odd-even alternations in both AEAs and AIPs as a function of size. In addition, the reliable vertical detachment energies (VDEs) and vertical ionization potentials (VIPs) are presented. The dissociation energies (DEs) of S (and/or its ion S((-/+))) from As n S3 species and their ions were calculated to examine relative stabilities. The hardnesses and HOMO-LUMO gaps of As n S3 (n = 1-6) were evaluated and used to discuss relative chemical reactivity.