The HSSS radical and the HSSS- anion.

The HS3 radical and the HS3(-) anion, the sulfur analogues of HO3 and HO3(-), have been detected for the first time by mass spectrometric experiments performed in the gas phase. The structural and energetic features of HS3 and HS3(-) have been investigated by ab initio calculations. Both HS3 and HS3(-) are characterized by HSSS open-chain structures, stable toward the dissociation into S2 and HS(0/-). HS3 adds to HS and HS2 as the known HS n species, and HS3(-) is the conjugate base of a strong Brønsted acid, the trisulfane HSSSH.