The gas phase nitrogen disulfide radical (SNS)

Collisional activation and neutralization—reionization mass spectrometric experiments provide evidence for the gas phase existence of the symmetrical nitrogen disulfide radical (S-N-S, 2A1) as well as the corresponding cation (S-N-S+, 1Σg+). Thiadiazolothiadiazole has been employed as the precursor. Ab initio molecular orbital calculations at the QCISD(T)/6–311 + + G(3df, 2p)/ /MP2/6–311 + + G(d, p) + ZPE level lead to the following thermochemical data: heats of formation at 0 K (Δ Hf,00 in kcal/mol): S-N-S: 66 ± 3, N-S-S: 85 ± 3, S-N-S+: 240 ± 3, N-S-S+: 311 ± 3 and HS-N-S: 59 ± 3; proton affinity PA(SNS) = 169 ± 3 kcal/mol and ionization energies IEa(SNS) = 7.5 ± 0.2 eV and IEa(HS-N-S) = 8.7 ± 0.2 eV.