The determination of thermodynamics of oxygen complexes of anions of sulfur dioxide and fluoronitrobenzenes using atmospheric pressure ionization mass spectrometry

The thermodynamic properties of oxygen complexes of the negative ions of 1-fluoro-2,4-dinitrobenzene (FDNB), 1,5-difluoro-2,4-dinitrobenzene (DFDNB), and sulfur dioxide have been determined by measuring the temperature dependence of the pertinent ion ratios by using a mass spectrometer equipped with a⁶³Ni atmospheric pressure ionization source. The values of -H° and -S°are SO₂^–(O₂), 101 ± 2.1 kJ mole¹ and 121 ± 3.8 J/K-mole; FDNB^–(O₂), 51.5 ±3.4 kJ mole^–1 ± 9.2 J/K-mole; and DFDNB^–(O₂), 65.7 ± 0.4 kJ mole^–2 and 110 ± 5.0 J/K-mole.