Synthesis, Characterization and Electronic Structure of Dirhenadehyro[12]annulene Complexes.

Treatment of the SiMe -protected dichloro-rhenium carbyne complexes Re{≡CCH=C(R)C≡CSiMe }Cl (PMe Ph) (R = CMe , 1-adamantyl) with CsF in methanol directly afforded the 12-membered metallacycles {ReCl(PMe Ph) } {≡CCH=C(R)C≡C-} . The electronic structure of the metallacycle was investigated by density functional calculations. The UV-vis spectrum of the metallacycle shows a red-shifted band compared to that of the starting dichlorocarbyne complex. Treatment of {ReCl(PMe Ph) } {≡CCH=C(CMe )C≡C-} with HCl produced the dichloro-rhenium carbyne complex Re{≡CCH=C(CMe )C≡CH}Cl (PMe Ph) , which is consistent with the electronic structure of the 12-membered metallacycles.