Nucleophilic substitution reactions of cyclopentadienyl and its related carbanions on tricarbonyl(η6-4-fluorotoluene)chromium: molecular structures of 1,4-bis [tricarbonyl(η6-4-toluene)chromium] cyclopentadiene, 3-[tricarbonyl(η6-4-toluene)chromium]indene

3-[Tricarbonyl(η6-4-toluene)chromium]indene (4) was obtained as the only separated product from the nucleophilic substitution of tricarbonyl(η6-4-fluorotoluene)chromium (1) with indenyl lithium. Presumably, a 1,3-shift of benzylic proton takes place after the attack of (1) by indenyl lithium during the formation of (4). Under similar reaction conditions, 1,4-bis[tricarbonyl(η6-4-toluene)chromium]cyclopentadiene (3) was detected as the only separaed bimetallicc product from continuous nucleophilic substitutions of cyclopentadienyl by (1). In this case, a 1,2-shift of the benzylic proton was observed during the formation of (3). Also,9,9-bis[tricarbonyl(η6-4-toluene)chromium]fluorene (7) was obtained from the consecutive nucleophilic substitutions of fluorenyl by (1). No proton shift is possible after the formation of (7). Presumably, the nucleophilic substitutions take place directly on the fluorine-bearing carbon in all these cases. Compounds were characterized by mass, infrared, 1H, 13C NMR spectra. The molecular structures of 3, 4 and 7 have been determined by X-ray diffraction.