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

Treatment of the SiMe3-protected dichloro-rhenium carbyne complexes Re{equivalent to CCH=C(R)C equivalent to CSiMe3}Cl-2(PMe2Ph)(3) (R = CMe3, 1-adamantyl) with CsF in methanol directly afforded the 12-membered metallacycles {ReCl(PMe2Ph)(3)}(2){equivalent to CCH=C(R)C equivalent to 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(PMe2Ph)(3)}(2){equivalent to CCH=C(CMe3)C equivalent to C-}(2) with HCl produced the dichloro-rhenium carbyne complex Re{equivalent to CCH=C(CMe3)C equivalent to CH}Cl-2(PMe2Ph)(3), which is consistent with the electronic structure of the 12-membered metallacycles.