Vibrational study of ionic association in aprotic solvents—I. The ion pairs of alkali and silver thiocyanate in dimethylformamide or dimethylthioformamide

Raman Spectroscopic Characterization of Association and Thermoreversible Gelation in Aqueous Systems of Poly(N-acetamidoacrylamide)

“…The vibrational spectrum of thiocyanate ion has three fundamental frequencies: − ν 1 (C−N stretching) at 2065 cm -1 , ν 2 (bending) at 470 cm -1 , and ν 3 (C−S stretching) at 750 cm -1 . Both C−S and C−N stretchings are reported to be sensitive to the complex formation, , and therefore the knowledge about their spectral behavior in each certain system can bring information about the SCN ion configuration.…”

Influence of solute-solvent coordination on the orientational relaxation of ion assemblies in polar solvents

“…Extensive experimental studies using FTIR, Raman, and NMR spectroscopy have been used to determine the nuclear structure associated with each CN-stretch peak in the FTIR spectra. 25,[33][34][35][36] The peak at 2073 cm −1 corresponds to the CN stretch absorption of the ion pair, 25,36 the peak at 2042 cm −1 corresponds to the CN stretch absorption of an ion-pair dimer with a quadrupole charge distribution (Q-dimer), 35,36 and the small blueshifted peak in MeNO 2 at 2102 cm −1 corresponds to the thiocyanate anion coordinating Li and nitromethane (MeNO 2 : dashed red line). The peak at ∼2040 cm −1 corresponds to an ion-pair dimer structure with a quadrupole charge distribution (Q-dimer), the peak at ∼2070 cm −1 corresponds to the LiNCS ion pair, and the peak at ∼2100 cm −1 corresponds to the NCS − in a linear ion-pair dimer (L-dimer) that is coordinating two Li + cations, one with the N atom and the other with the S atom.…”

“…23,24 Here we have used the technique to study the rotational dynamics of lithium thiocyanate (LiNCS) dissolved in various polar solvents. LiNCS forms several types of ionic assemblies in solution depending on the LiNCS concentration and the properties of the solvent, with the CN-stretch frequency providing a sensitive marker of the distinct ionic structures [25][26][27][28][29] and an excellent probe of orientational dynamics because of the long vibrational excited state lifetime. 24,[28][29][30][31] In strong polar solvents with Lewis base electron donating properties, such as dimethyl sulfoxide and acetonitrile, LiNCS exists predominantly as free ions at low ionic concentration and ion pairs at high concentration.…”

Vibrational spectroscopic study of the ionic association and ion-pair structures in solutions of silver(I), copper(I) and thallium(I) thiocyanates in N,N-dimethylthioformamide

“…To analyse the concentration of unpaired thiocyanate anion in DMTF solutions, it is necessary to obtain its IR molar absorption coefficient which, although known in several solvents, 15,16,29 has not yet been evaluated in DMTF solutions. Because of the low solubility of K(SCN) in DMTF (pK sp \ tetrabutylammonium thiocyanate has 3.3), 30 [NBu 4 (SCN)] been used as the non-associating solute.…”

“…To the best of our knowledge, the only vibrational spectroscopic (IR) studies published on silver(I) or copper(I) thiocyanate solutions in DMTF are from Chabanel and coworkers. 15,16 In these studies the thiocyanate structure of the ionic pair Ag(SCN), and the isothiocyanate structure of the corresponding Cu(NCS) are demonstrated. The equilibrium constant of the ionic pairing processes, however, are not reported in these works.…”