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Proton affinities of n-alkylamines, n-alkyl thiols, n-alcohols and the ammonium affinities of n-alcohols up to C-18 were calculated and they were all found to be co-relating linearly. The calculated PA's make it clear that NH3 is an appropriate reactant gas for the formation of the so-called 'quasi-molecular ions' of thiols and alcohols in CIMS.

Abstract: For the first time, a study has been made of H2S as a reactant gas in positive-ion chemical-ionization mass spectrometry. To this end, the mass spectrum of an H2S plasma was recorded, and the energies and structures of the ions were examined. The most stable structures of the plasma ions H3S+, S2 +, H2S2 +, H3S2 +, [H2S···H3S]+, H2S3 +, H3S4 + and HS n + were obtained by the ab initio G3B3 method, in which the G3 method is extended with B3LYP/6-31G(d). Of the three isomers of H2S3 +, the C 2V structure, with terminal hydrogen atoms, proved to be the lowest energy. The structure of the adduct [H2S···H3S]+ was found to be comparable with that of the water adduct [H2O···H3O]+. An enthalpy of −59.9kJmol−1 was calculated for the reaction H3S+ +H2S→[H2S···H3S]+ and the exothermic reaction enthalpies of the polysulfonium ions, formed according to the equation HS n + +S→HS n+1 +, lie in the range 225–347kJmol−1 for n =1–8. [Copyright &y& Elsevier]

The title compound, C20H19F3N2O4, crystallizes with two mol­ecules in the asymmetric unit. The important characteristics of the mol­ecule are the two C=N bonds in Z,E configuration, one in the β-methoxy-system and the other in the oxy­methyl side chain between the two aromatic rings. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, C20H19F3N2O4, contains one mol­ecule in the asymmetric unit. The CF3 group is disordered over two positions. The important characteristics of the mol­ecule are the two C=N bonds in an E,Z-configuration, viz. E in the β-methoxy system and Z in the oxymethyl chain between the two aromatic rings. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, C19H17F3N2O4, a metabolite of the fungicide trifloxy­strobin (TFS), contains one mol­ecule in the asymmetric unit. The CF3 group is disordered over two positions. The important characteristics of the mol­ecule are the two C=N bonds in an E,E configuration, one in the β-methoxy system and the other in the oxy­methyl side chain between the two aromatic rings. The mol­ecules are linked via an O—H⋯N hydrogen bond and an infinite spiral is formed along the b-axis direction. [ABSTRACT FROM AUTHOR]