IR spectra and microstructure of electrolyte solutions. Dependence of spectroscopic characteristics of solvated molecules on composition of solvates in the system CH3CN–Mg(ClO4)2–DMF

Abstract

The integrated intensities of the ν(CC) and ν(CN) stretching vibration bands of acetonitrile (CH₃CN) molecules, the δ(OCN) bending vibration band of N,N-dimethylformamide (DMF) molecules, and the ν₃ and ν₄ bands of perchlorate anions (ClO₄⁻) in ternary CH₃CN–Mg(ClO₄)₂–DMF solutions were measured. The obtained experimental data show that DMF molecules have a greater ability to solvate cations than CH₃CN molecules. The spectroscopic properties of CH₃CN and DMF molecules located in the first coordination sphere of a cation depend on the composition of the solvate: the absolute intensities of the ν(CC) and ν(CN) bands of CH₃CN molecules and of the δ(OCN) band of DMF molecules decrease when the number of DMF molecules in the first solvation shell of the cations increases. Electron transfer from the solvent molecules to the cations is discussed. The influence of the electrostatic field of the cations on the electro-optical parameters of the bonds of the solvated molecules decreases due to this effect.