Cyclic Diynes with Dimethylsilyl and Dimethylgermyl Groups in the Bridges. Syntheses and Properties.
In: Organometallics, Jg. 18 (1999) ; Nr. 18, S. 3615-3622
Zeitschriftenaufsatz / Fach: Chemie
The syntheses of the cyclic diynes, e.g. I (n = 2-4) could be achieved. Common to all of them are one dimethylsilyl group, one dimethylgermyl group, two dimethylsilyl groups, two dimethylgermyl groups, or three dimethylsilyl groups in the bridges between the triple bonds. X-ray investigations on the single crystals of I (n = 2-4) reveal twisted chair like conformations in the solid state. The He I PE spectra show a very strong splitting of 0.9-1.2 eV between the bands assigned to the removal of electrons from the p i- and pi+ orbitals of the 10-membered ring. The first ionization energy varies between 8 and 9 eV.