Infrared and Ultrasonic Spectra of Sodium Thiocyanate and Lithium Thiocyanate in Tetrahydrofuran.
Abstract
Infrared spectra of sodium thiocyanate solutions and of lithium thiocyanate solutions in tetrahydrofuran (THF) in the wavenumber range 2000-2200/cm are reported. The digitized spectral envelope, which is due to the out of phase stretch of the SCN anion, is quantitatively described by the sum of three Gaussian-Lorentzian product functions. The three spectral bands are assigned respectively to the N-bonded pairs (approx. 2057/cm for NaNCS, approx. 2064/cm for LiNCS), to the dimers or quadrupoles (approx. 2043/cm for (NaNCS)2), 2040/cm for (LiNCS)2, and tentatively to triple ions (2074/cm for sodium thiocyanate, approx. 2086/cm for lithium thiocyanate). The maximum absorbances per unit lenght of cell are expressed as a function of concentrations by cubic polynomial functions. Ultrasonic spectra for sodium thiocyanate solutions in the THF in the frequency range 0.5-400 MHz are described by the sum of two Debye relaxation functions. For lithium thiocyanate solutions in the THF, the ultrasonic spectra are described by a single Debye relaxation function. The limitations of the infrared method in giving reliable formation stoichiometric constants in media of low permittivity are discussed. The advantage of combining the structural information from vibrational spectra to the kinetic results of the ultrasonic spectra for a molecular interpretation of the latter ones is reiterated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1986
- Accession Number
- ADA163765
Entities
People
- D. Saar
- S. Petrucci