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.