Li+-molecule interactions of lithium tetrafluoroborate in propylene carbonate plus N,N-dimethylformamide mixtures: An FTIR spectroscopic study

FTIR (Fourier transformed infrared) spectra have been collected and analyzed for solutions of lithium tetrafluoroborate in propylene carbonate (PC), N,N-dimethylformamide (DMF), and PC + DMF mixtures. The band splitting and symmetric ring deformation for PC and O=C-N deformation for DMF suggest that there is a strong interaction between lithium cations and solvent molecules. The solvent molecules have been assigned to two types, the free and complexed molecules. By a comparison of the intensity for the corresponding bands, it has been concluded that Li+ cations are preferentially solvated by DMF molecules in the LiBF4/PC + DMF solutions. This has been explained by the difference in values of donor number (DN). (C) 2014 Elsevier B.V. All rights reserved.