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

Treatment of the SiMe 3 ‐protected dichloro‐rhenium carbyne complexes Re{≡CCH=C(R)C≡CSiMe 3 }Cl 2 (PMe 2 Ph) 3 (R = CMe 3 , 1‐adamantyl) with CsF in methanol directly afforded the 12‐membered metallacycles {ReCl(PMe 2 Ph) 3 } 2 {≡CCH=C(R)C≡C−} 2 . 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 2 Ph) 3 } 2 {≡CCH=C(CMe 3 )C≡C−} 2 with HCl produced the dichloro‐rhenium carbyne complex Re{≡CCH=C(CMe 3 )C≡CH}Cl 2 (PMe 2 Ph) 3 , which is consistent with the electronic structure of the 12‐membered metallacycles.