title: Synthesis and Properties of Bridgehead-Functionalized Permethylbicyclo[2.2.2]octasilanes.
abstract: A series of previously unknown bridgehead-functionalized bicyclo[2.2.2]octasilanes, Me3Si-Si8Me12-X, X-Si8Me12-X, and X-Si8Me12-Y [X, Y = -SiMenPh3-n(n= 1, 2) (2,3,10), -SiMe2Fc (Fc = ferrocenyl) (4,11,13,14), -COR (R = Me,tBu) (6,7,12), COOMe (8), COOH (9)], have been prepared by the reaction of the silanides Me3Si-Si8Me12-K+or K+-Si8Me12-K+with proper electrophiles and fully characterized. The molecular structures of2,3,4,6,8,9,10, and13as determined by single-crystal X-ray diffraction analysis exhibit a slightly twisted structure of the bicyclooctasilane cage. Endocyclic bond lengths, bond angles, and dihedral angles are not influenced considerably by the substituents attached to the bridgehead silicon atoms. Due to σ(SiSi)/π(aryl) conjugation, a 20-30 nm bathochromic shift of the longest wavelength UV absorption band relative to Me3Si-Si8Me12-SiMe3(1) is evident in the UV absorption spectra of the phenyl and ferrocenyl derivatives. Otherwise, UV absorption data do not support the assumption of aryl/aryl or aryl/C=O interaction via the σ(SiSi) bicyclooctasilane framework.
authors.affiliation: Institute of Inorganic Chemistry, Graz University of Technology , Stremayrgasse 9, A-8010 Graz, Austria.
authors.forename: Harald
authors.initials: H
authors.lastname: Stueger
authors.forename: Bernd
authors.initials: B
authors.lastname: Hasken
authors.forename: Uwe
authors.initials: U
authors.lastname: Gross
authors.forename: Roland
authors.initials: R
authors.lastname: Fischer
authors.forename: Ana
authors.initials: A
authors.lastname: Torvisco Gomez