Synthesis and X-ray crystal structure analysis of a Cp-substituted phosphaferrocene

At 140°C in THF, a 2,3,4,5-tetramethyl-1-cyclopentadienylide anionic substituent migrates from phosphorus to the α-carbon of the corresponding P-substituted 3,4-dimethylphosphole 2. The resulting 2-cyclopentadienyl-3,4-dimethylphospholide ion (3) reacts with a [CpFe]⁺ source to give the corresponding 2-cyclopentadienyl-3,4-dimethyl-1-phosphaferrocene (5) as a mixture of two diastereomers, one of which has been characterized by X-ray crystal structure analysis.