SULFUR CLUSTER DIANIONS

Free dianionic sulfur clusters have been studied by standard ab initio methods. Chainlike S-n(2-) isomers have been found to exhibit nonline ar twisted geometries, and the onset of electronic stability in this s eries is predicted to occur at n = 7. S-8(2-) is the smallest system c learly stable with respect to electron autodetachment and is predicted to be sufficiently long-lived to allow the observation in a mass spec trometer, Branched isomers have been found to be electronically more s table than the corresponding chainlike isomers but are expected to be more sensitive to fragmentation. The bonding mechanisms of the excess electrons in the different isomers are discussed, and The stable syste ms are compared to other small gas-phase dianions, Our results broaden the overall picture of isolated dianionic species.