ISSN:
0377-0486
Schlagwort(e):
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The totally symmetric ν1 vibrational modes of the anions N3- and NO3- have been studied in aqueous solution with very high precision. The effect of different alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) has been systematically recorded as a function of the solution concentration. The experimental results show that the anion ν1 mode frequencies are dependent on both the cation present and on the solution concentration. Extrapolation of the experimental data yielded precise values of the anion ν1 frequencies in the limit of infinite dilution. These frequencies are 1342.7 ± 0.1 cm-1 for N3- and 1047.4 ± 0.1 cm-1 for NO3-. When Li+ or Na+ was present in solution with the azide anion, the ν1 frequency was shifted to a higher value than the infinite dilution frequency, with both cations having approximately the same effect, whereas when K+, Rb+ or Cs+ was present the ν1 frequency was decreased, the largest decrease being caused by Cs+, followed by Rb+, with the smallest decrease being caused by K+. In the case of the nitrate anion, the cations Na+, K+, Li+ and Rb+ were all responsible for an increase in the NO3- ν1 frequency with respect to the infinite dilution value, with the magnitude of the perturbation decreasing from Na+ to Rb+. When Cs+ was present the NO3- ν1 frequency was observed to decrease by a very small amount. It is suggested that for the vibrationally excited azide anion, the cation perturbation occurs through a form of polarizability interaction. However, the cation-nitrate anion interaction is thought to occur through the effect that the hydrated cation has on the vibrationally excited nitrate anion cosphere of hydration.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jrs.1250160105
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