Phosphaferrocenes Containing the Chiral Pinene-Fused Cyclopentadienyl Ligand PCp

The chiral PCp-substituted phosphaferrocene 7 was prepared from the dimeric iron carbonyl complex [PCpFe(CO)2]2 (5) and t-butylphosphole (PCp=pinene-fused cyclopentadienyl). In 7, the PCp ligand is coordinated to the iron atom via its exo-side as shown by X-ray crystallography. Formylation of the sandwich complex 7 leads to a mixture of the diastereomeric aldehydes 10a,b in an approximate ratio of 2:1. As a side-product of the synthesis of 7, the homoleptic ferrocene (PCp)2Fe (8) was obtained by a ring ligand transfer reaction. Complex 8 is formed as a single C2-symmetrical isomer.