title: The Electrochemical Synthesis of Polycationic Clusters.
abstract: As a new method for the synthesis of chalcogen polycationic clusters, the electrochemical dissolution of elemental tellurium in ionic liquids (IL) or in liquid SO2 is presented. ILs used are ethylmethylimidazolium triflate [OTf](-) and tetraalkylammonium triflylimide [NTf2](-). Tristriflylmethanide [CTf3](-) was used as [BuMeIm][CTf3] as the electrolyte in SO2. This allowed for the isolation of [Te4][CTf3]2, [Te6][OTf]4, and [Te8][NTf2]2 containing the square [Te4](2+), the prismatic [Te6](4+), and the novel barrelane-shaped [Te8](2+). The compounds are novel compositions as they do not contain the usual halometalate anions, but rather common weakly coordinating anions. The (125)Te NMR spectrum of an IL solution containing [Te8](2+) features only one broad signal at 2700 ppm. DFT calculations show that slight concerted displacements within the [Te8](2+) cluster lead to a fluxional molecular structure and a fast valence isomerism with a very low activation barrier of about 8 kJ mol(-1).
authors.affiliation: Institute for Inorganic Chemistry, University of Bonn, 53121, Bonn, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Schulz
authors.affiliation: Institute for Inorganic Chemistry, University of Bonn, 53121, Bonn, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Daniels
authors.affiliation: Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, 53115, Bonn, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bredow
authors.affiliation: Institute for Inorganic Chemistry, University of Bonn, 53121, Bonn, Germany. j.beck@uni-bonn.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Beck
keywords: 125Te NMR spectroscopy; electrolysis; ionic liquids; polycations; tellurium