Diol functionalized ionic liquids (DFILs) with various anions as a ligand have been investigated for the copper(I)-catalyzed C-S coupling reaction. The dependence of reactivity and selectivity of the ionic liquids on the anion was demonstrated by experimental studies and supported by Density Functional Theory (DFT) calculations. The interaction energies obtained from the DFT calculations showed a good agreement with the experimental yields of the products.