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Abstract: The new nitrogen-rich oxide N3O has been detected in the gas phase by mass spectrometric experiments. The radical has been assigned a minimum lifetime of 0.7μs and an open-chain NNNO structure in the quartet state. Structures and energies of the N3O+ precursor ion and the N3O radical have been investigated by ab initio calculations. [Copyright &y& Elsevier]

Abstract: A theoretical study performed at B3LYP and CCSD(T) level of theory of the reaction of formation of S3O+ in ionized carbonyl sulphide/disulphur monoxide mixtures is reported here. The interaction of carbonyl sulphide with disulphur monoxide cation leads to three different [CS3O2]+ isomers, essentially formed by a S3O+ cation solvated by a CO molecule. The S3O+ cation is present in the three structures cis, trans and ring, showed also by the isolated S3O+ species. The complex with the ring S3O+ unit is the most stable, but a direct path to its formation starting from OCS and S2O+ has not been found in the potential energy surface of [CS3O2]+. This species can be obtained from the isomerization of the complexes containing the cis or trans S3O+ unit, overcoming relatively low barrier heights. [Copyright &y& Elsevier]

Abstract: ions are shown to be formed in ionized O2/CH4 mixtures from the secondary reaction of CH2O+ with O2. By high-resolution mass spectrometric techniques, the peroxide HOOH structure and the H2CO structure of ionized formaldehyde are assigned to the [H2O2]+ ions and the [CH2O]+ reactants, respectively. The [CH4O2]+ intermediate of the reaction between and CH4 is characterized as a mixture of the loosely bound complex and the theoretically predicted insertion product CH3OOH+. The CH3OOH+ intermediate, precursor of the most abundant ionic product CH2OOH+, has been characterized for the first time as a long-lived species. [Copyright &y& Elsevier]

Abstract: The oxywater cation H2OO+ was generated in the gas phase by ionization of mixtures containing O3, O2 and H2O. Different ionic mixtures, rich in either the H2OO+ or the HOOH+ isomer, were obtained by O3/O2/H2O–O2/H2O CI, and by CH3OH/O2–CH2O/O2 CI, respectively. The H2O2 + ions were characterized by high-resolution CAD mass spectrometry, and structural and energetic effects were examined. [Copyright &y& Elsevier]

The HOOO− anion, the conjugate base of dihydrogen trioxide, HOOOH, is suggested as a key intermediate in ozonation reactions relevant to atmospheric chemistry, water purification, preparative organic chemistry, etc. Whereas recent theoretical calculations characterize HOOO− as a long-lived metastable species, so far the anion proved experimentally elusive, defying attempts at its direct detection even in solution, where it should be stabilized by solvation. We report the preparation and the proof-positive detection of HOOO− as an isolated species with a lifetime >0.8 μs. The preparation proved particularly difficult, since the only viable approach is the indirect route involving the preliminary formation of HOOO⋅ upon neutralization of HOOO+, followed by electron attachment to the radical, utilizing neutralization–reionization (+NR−) mass spectrometry. Direct two-electron reduction of the HOOO+ cation to the HOOO− anion by the vertical process typical of charge reversal (CR) experiments proved inefficient. This observation, and application of neutral and ion decomposition difference (NIDD) mass spectrometry, pioneered by Schwarz and coworkers [Int. J. Mass Spectrom. Ion Processes 172 (1998) 181] suggest that the geometries of HOOO+ and HOOO− are significantly different, whereas that of the HOOO⋅ radical is structurally intermediate between them, which accounts for the diversity of the Franck–Condon factors characterizing the mutual vertical transitions of the three species. This inference is consistent with the available optimized geometries of HOOO⋅ and HOOO+, computed at various levels of theory, and with that of the anion recently reported by Plesnica˘r et al. [J. Am. Chem. Soc. 124 (2002) 8462]. [Copyright &y& Elsevier]