Reactions of [(CO)(3)Mn(eta(5)-Thi)](+) (Thi equals thiophene or 2,5-dimethylthiophene) with nucleophiles

The eta(5)-thiophene complexes, [(CO)(3)Mn(eta(5)-T)](+) (1) and [(CO)(3)Mn(eta(5)-2,5-Me(2)T)](+) (2), react with LiCuR(2) (R = Me or Ph) by adding R(-) to the sulfur atom of the thiophene, which gives the eta(4)-thiophene complexes, (CO)(3)Mn(eta(4)-T . R) and (CO)(3)Mn(eta(4)-2,5-Me(2)T . R). An X-ray study of (CO)(3)Mn(eta(4)-T . C6H5) (6) shows the eta(4)-T . C6H5 ligand to be coordinated to the manganese through the four thiophene carbon atoms, while the sulfur bearing the phenyl group is bent away from the metal. The structure of 6 supports previous suggestions that the sulfur in eta(5)-thiophene complexes is an electrophilic center. Reactions of 1 or 2 with RS(-), CH3O-, or (CH)-C--(CO2CH3)(2) nucleophiles result in the displacement of thiophene with the formation of [(CO)(4)Mn(mu-SR)](2) or Mn-2(CO)(10). The structure of [(CO)(4)Mn(mu-SC6H4CH3-p)](2) (9), established by X-ray studies, is also reported.