Cluster Salts [Nb₆Cl₁₂(HIm)₆]A_n (with HIm=1H‐imidazole and A=Mineral Acid Anion, n=1 or 2) Made in and with Brønsted‐basic Ionic Liquids and Liquid Mixtures

Abstract

Four new hexanuclear niobium cluster compounds of the general formula [Nb6Cl12(HIm)6](A)n ⋅ x(solvent molecule) (HIm=1H‐imidazole, A=mineral acid anion, Cl− (n=2) (1), (SO4)2− (n=1) (2), (CrO4)2− (n=1) (3), and (HAsO4)2− (n=1) (4)) were prepared. Their synthesis can be done in basic ionic liquids, which form on the addition of a mineral acid, which also delivers the counter anion for the final cluster compound, to an excess of the 1H‐imidazole. Some addition of an auxiliary solvent, like methanol, improves the speed of crystallisation. The cluster unit comprises a hexanuclear Nb6 unit of octahedral shape with the edges bridged by Cl atoms and the exo sites being occupied by N‐bonded 1H‐imidazole ligands. The cluster cation carries sixteen cluster‐based electrons. Between the NH groups of the ligands of the cluster unit, the anions and the co‐crystallised water (1), or 1H‐imidazole and methanol molecules (2, 3, and 4) a network of hydrogen bonds exists.