1,1′,2,2′-Tetralithioferrocene and 1,1′,2,2′,3,3′-Hexalithioferrocene: Useful Additions to Ferrocene Precursor Compounds

The direct synthesis of 1,1′,2,2′-tetralithioferrocene from 1,1′,2,2′-tetrabromoferrocene is reported. In addition, the related 1,1′,2,2′,3,3′-hexalithioferrocene is also described, prepared directly from 1,1′,2,2′,3,3′-hexabromoferrocene. These lithioferrocenes may be isolated as orange red (tetralithio) and red (hexalithio) powders, respectively. When these are prepared in situ and reacted with chlorotrimethylsilane, the corresponding 1,1′,2,2′-tetrakis(trimethylsilyl)ferrocene and 1,1′,2,2′,3,3′′ -hexakis(trimethylsilyl)ferrocene are obtained as red and crimson crystalline solids, respectively. The single-crystal structures of 1,1′,2,2′-tetrakis(trimethylsilyl)ferrocene (11) and 1,1′,2,2′,3,3′-hexakis(trimethylsilyl)ferrocene (12) have been determined and are described.