A P‐Functionalized [3]Ferrocenophane with a Dynamic SPS‐Bridge

Ferrocene‐1,1′‐dithiol reacts with PCl 3 and P(NMe 2 ) 3 to give [3]ferrocenophanes with SPS‐ ansa ‐bridges comprising potentially reactive P−Cl and P−N bonds at the central bridge atom. The products were characterized by NMR data and single‐crystal XRD studies. The P‐chloro‐derivative exists both in the solid state and in solution as a mixture of two energetically nearly degenerate conformers with different stereochemical disposition of the ansa ‐bridge. Activation parameters for the dynamic equilibration between both isomers in solution were determined by dynamic NMR spectroscopy. Computational studies suggest that the isomerization proceeds via a torsional motion of the bridging SPS‐unit rather than via configuration inversion at the phosphorus atom.