Synthesis and Characterization of Rhenabenzyne Complexes

Reactions of [ReH 5 (PMe 2 Ph) 3 ] with alkynols HC≡CC(OH)(R)C≡CSiMe 3 (R= t Bu, i Pr, 1‐adamantyl) in the presence of HCl give the vinylcarbyne complexes [Re{≡CCHC(R)C≡CSiMe 3 }Cl 2 (PMe 2 Ph) 3 ], which react with t BuMgCl to give [Re{≡CCHC(R)C≡CSiMe 3 }HCl(PMe 2 Ph) 3 ]. Treatment of [Re{≡CCHC(R)C≡CSiMe 3 }HCl(PMe 2 Ph) 3 ] with n Bu 4 NF gives [Re{≡CCHC(R)C≡CH}HCl(PMe 2 Ph) 3 ], which first isomerizes to the bicyclic complexes [Re{CHCHC(R)CCH}Cl(PMe 2 Ph) 3 ], and then to the rhenabenzynes [Re{≡CCHC(R)CHCH}Cl(PMe 2 Ph) 3 ]. The NMR spectroscopic and structural data as well as the aromatic stabilization energy (ASE) and nucleus‐independent chemical‐shift (NICS) values suggest that these rhenabenzynes have aromatic character.