Abstract
Treatment of CpW(CO) 2 (η 4 -cyclohexadiene)-BF 4 with RMgBr (R = methylvinyl, phenyl, naphthyl) in cold THF (-78°C) afforded the CpW(CO) 2 [(1,2,4-η-1-CO-2-R-cyclohexene] complex as the major product; this result provides an example of a nucleophile attacking the internal carbon of a cationic η 4 -diene fragment.