Polynuclear Metal Complexes Obtained from the Task-Specific Ionic Liquid Betainium Bistriflimide

The task-specific ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was used to dissolve metal oxides and hydroxides. The crystal structures of the resulting metal betaine bistriflimide complexes exhibit a rich structural variety. A trimeric structure was found for the cobalt(II) compound, [Co3(bet)8(Hbet)2(H2O)2][Tf2N]9[Hbet], a tetrameric structure for the manganese(II) and zinc(II) compound, [Mn4(bet)10(H2O)4][Tf2N]8 and [Zn4(bet)10(H2O)2][Tf2N]8, respectively, a pentameric structure for the nickel(II) compound, [Ni5(bet)12(H2O)6][Tf2N]10, an oxo-hydroxo-cluster formation for the lead(II) compound, [(Pb4O)Pb(OH)(bet)8(Tf2N)3][Tf2N]4·MeOH, and a polymeric structure for the silver(I) compound, [Ag2(bet)2(Tf2N)Ag2(bet)2][Tf2N]3. The zwitterionic nature of the betaine ligand and the weakly coordinating ability of the bis(trifluoromethylsulfonyl)imide [Tf2N]− anion facilitates the incorporation of metal ions into oligonuclear and polynuclear metal complexes.