Synthesis and Characterization of Dirhenadehydro[12]annulenes.

The 12-membered-ring metallacycles [mer-Re{≡CCH=C(R)C≡C−}Cl(PMe2Ph)3)]2 (R=CMe3, 1-adamantyl), which are organometallic analogues of antiaromatic octadehydro[12]annulene, are prepared by heating the methyl carbyne complexes mer-Re{≡CCH=C(R)C≡CH}(CH3)Cl(PMe2Ph)3. An intermolecular σ-bond metathesis between the Re−CH3 bond and the acetylenic C−H bond is proposed for their formation. [ABSTRACT FROM AUTHOR]