title: A cyclopentadienide analogue containing divalent germanium and a heavy cyclobutadiene-like dianion with an unusual Ge4 core.
abstract: The first isolable cyclogermylidenide salt 2 has been synthesized and isolated by facile dehalogenation of the N-heterocyclic chlorogermylene 1 with elemental potassium in ether and isolated in the form of yellow crystals in 33% yield. Single-crystal X-ray diffraction analysis revealed that 2 crystallizes as a dimeric half-sandwich complex of aromatic C3NGe rings interconnected via intermolecular Ge(II)-->K dative bonds. Its yield can be improved up to 42% by gentle reduction of 1 (or its related GeCl3 complex 8) using potassium graphite. Additionally, the remarkable K2Ge4 cluster compound 9 has been isolated as a side product which consists of an unusual dianionic Ge4 core with parallelogram configuration and pronounced aromaticity as indicated by highly negative NICS values.
authors.affiliation: Institute of Chemistry, Metalorganics and Inorganic Materials, Technische Universität Berlin, D-10623 Berlin, Germany.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Wang
authors.forename: Shenglai
authors.initials: S
authors.lastname: Yao
authors.forename: Christoph
authors.initials: C
authors.lastname: van Wüllen
authors.forename: Matthias
authors.initials: M
authors.lastname: Driess