CsC2H: Synthesis, crystal structure, and spectroscopic properties

CsC2H was synthesised by the reaction of caesium solved in liquid ammonia w ith acetylene. The crystal structure could be solved and refined from X-ray and neutron powder diffraction data (space group: R3c, Z=18). The structur e is characterised by C2H- trimers which are surrounded by caesium ions. Sp ectroscopic investigations (IR and Raman) of the stable monoalkalimetal ace tylides mainly confirm the data given in the literature and show that the a lkalimetal cation has a marked influence on the vibrational properties of t he C2H- anion.