Generation and electronic properties of lanthanide-cyclooctatetraene organometallic clusters in gas phase

Organometallic clusters of lanthanide (Ln = Nd, Er, Eu, and Yb) and 1,3,5,7-cyclooctatetraene (C₈H₈) were produced by a combination of laser vaporization and molecular beam methods. In the mass spectra of [Ln_n,(C₈H₈)_m], compositions of m = n + 1 were magic numbers. From mass spectrometry, photo-ionization spectroscopy, and photoelectron spectroscopy, we have concluded that these magic-numbered clusters take multiple-decker sandwich structures in which Ln atoms and C₈H₈ molecules are alternatedly piled up. These sandwich clusters are formed through ionic bonds composed of multiply charged cations [Ln^k+ (k = 2 and 3)] and multiply charged anions [C₈H^h-₈ (h = 1, 1.5, and 2)].