Dielectric relaxation of NaClO4 solutions in formamide, N-methylformamide, and N,N-dimethylformamide

Abstract

Complex permittivity spectra in the frequency range 0.95 ≤ v/[GHz] ≤ 89 for N,N-dimethylformamide (DMF), N-methylformamide (NMF), formamide (FA) and their solns. of NaClO4 are investigated to study the change of liq. structure and dynamics arising from the availability of one hydrogen-bond acceptor site together with no (DMF), one (NMF), or two (FA) donor sites on the same mol. Three solvent relaxation processes are obsd. for NMF and two for FA and DMF. The relaxation parameters are used to det. solvation nos. They show that ion-solvent interactions lead to a redn. of the av. length of the H-bonded NMF chains but have only moderate influence on the FA structure. An addnl. sol. relaxation process in DMF solns. is due to the diffusion-controlled formation and decompn. of solvent-shared ion pairs.