New Hexanuclear Niobium Cluster Compounds with Perfluorinated Ligands Made Using Ionic Liquids

Abstract

Three new hexanuclear niobium cluster compounds, which carry trifluoroacetate ligands on the exo sites of the metal atom octahedra, were synthesized and characterized. For the syntheses, the ionic liquid 1,1,3,3‐tetramethylguanidinium‐trifluoroacetat, (TMG‐H)TFA, was used as solvent as well as source for the ligands and cations. All three cluster compounds consist of the [Nb 6 Cl 12 (TFA) 6 ] 4– anion and (TMG‐H) + , (TMG‐H) + + (TMGTFAA‐H) + , or (TMGTFAA‐H) + cations [(TMGTFAA‐H) + = 1,1,3,3‐tetramethylguanidine‐trifluoroacetamidinium]. TMGTFAA and the corresponding cation are obtained by either heating and/or by addition of TFA‐anhydrate to (TMG‐H)TFA in a slow chemical reaction. (TMGTFAA‐H)TFA comprises a second ionic liquid in this reaction system, which provides cations for two of the three characterized niobium cluster compounds. Structural details of the three new cluster compounds as well as of TMGTFAA were obtained by X‐ray diffraction experiments. With a melting point of approx. 145 °C the cluster compound with the (TMG‐H) + cations almost can be called a “cluster ionic liquid“.