A theoretical investigation of the interaction between small Pd particles and 1-butyl-3-methyl imidazolium ionic liquids with Cl−, BF4− and PF6− anions

Abstract

Density functional calculations have been used to investigate the interaction between Pd_n clusters (n = 1–6) and 1-butyl-3-methylimidazolium (Bmim⁺) based ionic liquids (ILs) with the anions [Cl⁻], [BF₄⁻] and [PF₆⁻]. The interaction of small Pd_n clusters (1 ≤ n ≤ 6) with a single cation or anion is also studied. The interaction strengths in anion–Pd_n categories with n = 1–6 follow the trend [Cl⁻] > [BF₄⁻] > [PF₆⁻]. The cation could also form interactions with Pd_n clusters. Compared with a single anion or cation, the interaction could be strengthened when palladium particles interact with the whole ion pair. Further studies indicated that anion⋯Pd interaction is the decisive factor in the interaction between the Pd atom and the whole ion pair. The Pd₂ dimer interacts with the whole ion pair much more strongly than the Pd atom. Solvent effects have been considered in the present study by means of the polarizable continuum model. It is found that the stability of [Bmim⁺·BF₄⁻]–Pd_n and [Bmim⁺·PF₆⁻]–Pd_n complexes with n = 1 and 2 can be improved in solvents.