title: Unusual bonding in trisilaallene and related heavy allenes.
abstract: The synthesis, X-ray and spectroscopic analysis, and unusual bonding and structure among heavy group-14 element congeners of allene (heavy allenes) [R(2)M=M'=MR(2); M = M' = Si (1a), M = Si, M' = Ge (1b), M = Ge, M' = Si (1c), and M = M' = Ge (1d)] are comparatively discussed. Using DFT calculations and PMO theory, the origin of the bent and fluxional skeleton of the heavy allenes is ascribed to the Jahn-Teller distortion associated with the effective pi-sigma* mixing (pi-sigma* distortion). This type of distortion is suggested to be a key concept for qualitative description of the unusual bonding of unsaturated compounds of heavy main-group elements.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan. mkira@mail.tains.tohoku.ac.jp
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kira
authors.forename: Takeaki
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Shintaro
authors.initials: S
authors.lastname: Ishida
authors.forename: Hidenori
authors.initials: H
authors.lastname: Masuda
authors.forename: Takashi
authors.initials: T
authors.lastname: Abe
authors.forename: Chizuko
authors.initials: C
authors.lastname: Kabuto