Thermochemistry of solvation of NO/sub 2//sup -/ and C/sub 6/H/sub 5/NO/sub 2//sup -/ by polar molecules in the vapor phase. Comparison with Cl/sup -/ and variation with ligand structure
The stabilities of NO/sub 2//sup -/ x HR and C/sub 6/H/sub 5/NO/sub 2//sup -/ x HR associations ions, where HR is a dipolar protic or aprotic organic molecule, have been investigated by the technique of pulsed electron beam high-pressure mass spectrometry. For comparison, analogous measurements were also made with Cl/sup -/. Equilibrium constants were determined as a function of temperature in order to define ..delta..H/sup 0/ and ..delta..S/sup 0/ values for solvation. The binding energies vary as NO/sub 2//sup -/ = Cl/sup -/ > C/sub 6/H/sub 5/NO/sub 2//sup -/ for ligands with -OH sites. On the average, the bond strength in C/sub 6/H/sub 5/NO/sub 2//sup -/ x HR complexes is found to be approx. 2.1 kcal/mol/sup -1/ lower than for those incorporating Cl/sup -/. For classes of ligands in which the nature of the bonding is expected to be similar, the binding energies increase with increasing acid strength of the ligand. With the exception of the aprotic ligands, CH/sub 3/NO/sub 2/ and CH/sub 3/CN, the association entropies for cluster ions incorporating NO/sub 2//sup -/ and C/sub 6/H/sub 5/NO/sub 2//sup -/ are significantly higher than those having C;/sup -/ as the core ion, and the values for complexation of a common ligand by NO/sub 2//sup -/ and C/sub 6/H/sub 5/NO/sub 2//sup -/ are essentially identical. Probable structures for C/sub 6/H/sub 5/NO/sub 2//sup -/ x HR ions are presented and discussed. 19 references 5 figures, 2 tables.
- Research Organization:
- National Bureau of Standards, Gaithersburg, MD
- OSTI ID:
- 7170044
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 89:25
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANIONS
SOLVATION
NITROGEN DIOXIDE
ORGANIC COMPOUNDS
BINDING ENERGY
CHEMICAL BONDS
CHLORINE
EQUILIBRIUM
EXPERIMENTAL DATA
HIGH PRESSURE
LIGANDS
MASS SPECTROSCOPY
MOLECULES
PH VALUE
POLAR COMPOUNDS
PULSE TECHNIQUES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
VAPORS
CHALCOGENIDES
CHARGED PARTICLES
DATA
ELEMENTS
ENERGY
FLUIDS
GASES
HALOGENS
INFORMATION
IONS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTROSCOPY
400201* - Chemical & Physicochemical Properties