Multiple-decker sandwich complexes of lanthanide 1,3,5,7- cyclooctatetraene [Ln(n)(C₈H₈)(m)] (Ln = Ce, Nd, Eu, Ho, and Yb); localized ionic bonding structure

Organometallic lanthanide complexes of Ln(n)(C₈H₈)(m) (Ln = lanthanide metals of Ce, Nd, Eu, Ho, and Yb; C₈H₈ := 1,3,5,7-cyclooctatetraene) were produced by a combination of laser vaporization and molecular beam methods. The complexes having (n, m) = (n, n + 1) for n = 1-5 were prominently produced as magic numbers in the mass spectra. Using mass spectrometry, photoionization spectroscopy, and photoelectron spectroscopy, it is concluded that these magic-numbered complexes form multiple decker sandwich structures in which Ln atoms and C₈H₈ molecules are alternately piled up. The obtained spectroscopic data show that these sandwich complexes are formed through ionic bonds and are charge transfer complexes, where the Ln atoms are multiply charged cations of Ln(k+) (k = 2 and 3) and C₈H₈ molecules are multiply charged anions.