| SYNTHESIS |
No examples of a metal atom occupying a position in a benzyne ring have been previously known, although many metallabenzenes are known and metal-benzyne complexes have been used as reaction substrates. Authors rationalized that a 14-electron transition-metal fragment should be a stable replacement for a carbon atom in benzyne, the same way a 15-electron fragment can replace a CH group to give metallabenzenes. The osmabenzyne (shown) was prepared by treatment of OsCl2[P(C6H5)3]3 with excess HC[CSi(CH3)3 in wet benzene. After the mixture was stirred for five days at room temperature, the osmabenzyne was isolated in 30% yield along with three lower yield osmium complexes. The X-ray structure of the osmabenzyne reveals a nearly planar ring, and the researchers suggest that the Os-C bond lengths are consistent with a delocalized system. The group is now making other metallabenzynes and probing their chemistry.
|