Journal of Chemical Physics vol:101 issue:6 pages:4885-4892
date:UNIV MONS,ORGAN CHEM LAB,B-7000 MONS,BELGIUM
An experimental and theoretical characterization has been carried out for the thionitroxyl radical (H2NS) and its ionic counterparts (H2NS)(+) and (H2NS)(-). Experimentally, (H2NS)(+) and (H2NS) have been detected by a combination of collisional activation and neutralization-reionization mass spectrometry. Thiourea has been used as a precursor. Theoretically, the neutral and ionic potential energy surfaces have been explored using (PU)MP4/6-311++G(3df,2p) energies based on (U)MP2/6-311++(d,p) geometries. Predictions for some spectroscopic and thermochemical properties have been made on the basis of molecular orbital calculations and empirical corrections. The rearrangements leading to the (HNSH) and (NSH2) isomeric species and the loss of hydrogen or other fragmentations have also been examined. The (HNSH) and (NSH2) species are less stable than their respective thionitroxyl isomers in all states considered. For the (H2NS)(+) cation, an H loss constitutes the lowest energy fragmentation followed by an H-2 elimination giving NS+ and a cleavage of the N-S bond. The thermochemical data are predicted as follows: Delta H-f,0(0) (H2NS)=31.2+/-3 kcal/mol, IE(a)(H2NS)=88.+/-0.2 eV, EA(a)(H2NS)=1.4+/-0.2 eV, PA(H2NS-)=357.5+/-3 kcal/mol as compared with the experimental value of 356.8+/-3 kcal/mol, Delta H-f,0(0)(HNS)=52.6+/-3 kcal/mol and Delta H-f,0(0)(H2NSH)=13.4+/-3 kcal/mol.