Phosphaalkenylidene bridged ferrocenes

The lithiation of ferrocenylphosphane Fc-PH2 (Fc = –C5H4FeC5H5) has been reinvestigated and both Fc-PHLi and Fc-PLi2 have been identified by NMR-spectroscopy. The lithiated phosphanides have been converted to the corresponding mono and bis(silylated) species the latter of which gave synthetic access to an oligomer in which three ferrocene units are symmetrically connected by phosphaalkene units. The charge distribution within this oligomer and its isomers has been analyzed using DFT calculations which indicates that the iron atom of the central metallocene unit is slightly more positive than the terminal ones. These findings are supported experimentally by Mößbauer spectroscopy and cyclic voltammetry.