Structure of the doubly charged C5O22− anion

The dianion C5O22− was recently observed mass spectrometrically as a half-integer peak at Arizona State University. Here the structure of this small gas-phase dianion is studied. Six C5O22− isomers are investigated with regard to their stability in the gas phase. Only one isomer is found to be stable with respect to electron autodetachment, yet, three other isomers are close to electronic stability, and examination of the repulsive Coulomb barriers shows that long (≫10−5 s) autodetachment lifetimes can be expected. Implications for larger doubly charged clusters are briefly discussed.