Electronic structure of NSO− and SNO− anions: Stability, electron affinity, and spectroscopic properties

Abstract

The low-energy electronic states of NSO anion and its SNO isomeric form for the singlet, triplet, and quintet spin multiplicities have been investigated by accurate ab initio approaches and large atomic basis sets. One-dimensional cuts of the three-dimensional potential energy surfaces (PESs) along selected interatomic distances and bending angles for these states have been calculated to assess the formation and stability of NSO(-) and SNO(-) in the gas phase. Results show that these anions have two low-energy states (X̃(1)A(') and 1(3)A″) that are bound and stable with respect to electron detachment. Owing to the energetic position of the dissociating asymptotes of the neutral and anionic species, several electronic excited states are suggested to be stable with respect to the electron autodetachment process in the long-range parts of the potentials before reaching the molecular region. The nature of the PESs in these regions and their implications and effects on the formation of SNO(-) from atomic and molecular fragments are discussed. This information is essential for a better understanding of the potential role of these species in diverse media.

Energetics, structure, and rovibrational spectroscopic properties of the sulfurous anions SNO− and OSN−

“…Interest in these anions and their corresponding neutral radicals has grown very recently due to their perceived importance in atmospheric, planetary (Venus, in particular), circumstellar, and interstellar contexts. [1][2][3][4][5] However, the literature is bereft of data on these anions from before 2015. The neutral radicals have been studied for over 40 years, [6][7][8][9][10][11] but exhaustive analysis of the reaction, electronic, and rovibrational physics of these systems has only recently emerged.…”

“…The neutral radicals have been studied for over 40 years, [6][7][8][9][10][11] but exhaustive analysis of the reaction, electronic, and rovibrational physics of these systems has only recently emerged. [1][2][3]12 There still exists controversy as to the attribution of vibrational features arising from the 2ν 3 overtone and ν 1 fundamental band in the 1500 cm −1 to 1650 cm −1 range. 1,2 The very bright nature of the SNO ν 1 band compared to the lesser 2ν 3 intensity will allow for conclusive assignment of the bands once gas-phase experiments on this system can be undertaken.…”

Photoelectron spectroscopy of the thiazate (NSO−) and thionitrite (SNO−) isomer anions

“…40 According to calculations performed here (EOMCCSD/aug cc pVQZ) and previously, 19 SNO -has several low lying electronic states which could be the cause of this.…”

“…11,19 When an electron is removed from this orbital, generating the radical neutral NSO in its ground electronic state, it is expected that the N S bond should lengthen (less bonding character) and the S O bond should shorten (less antibonding character) due to the change in bond order. This is seen in the calculated geometries of NSO -and NSO summarized in Table I.…”

“…16,17,19,20 Some of these studies were done in support of the matrix isolation experiments. 16,17 Recent work from Yazidi et al 20 and Trabelsi et al 19 also explored the electronic structure of the neutral radicals at a much higher level of theory than previously done (MRCI in Ref. 20 and CCSD(T) with an extrapolation to the complete basis set limit in Ref.…”