Homo/hetero interactions in the binary solutions of toluene with acetonitrile: FTIR spectroscopic, theoretical and dielectric studies

Abstract

FTIR spectroscopic studies has been carried out on the equimolar binary solution of toluene with acetonitrile which predicts the existence of molecular interactions. DFT calculations reveal that B3LYP functional with Grimme's dispersion correction D3 level is more suitable than the ωB97XD functional for investigating the molecular interactions in the toluene-acetonitrile system. These theoretical calculations suggest that the hydrogen bond interactions among the acetonitrile dimers through the n→σ∗ transitions are more stronger than any of the interactions in the 1:2 (toluene: acetonitrile) complex. However the stability of this complex is found to be more than that of the acetonitrile dimer as implied by their interaction energies. To investigate the effect of the homo/heterointeractions on the dielectric parameters of the toluene-acetonitrile solutions, dielectric relaxation studies has been carried out on these solutions over the entire composition range in the frequency range: 10 MHz–28 GHz at 298 K. Despite the presence of molecular interactions, linearity is observed in the εm vs X2 curve for some of the solutions.