Ferrocene and Pentaphosphaferrocene: A Comparative Study Regarding Redox Chemistry

摘要

Since its discovery and structural characterization in 1951, ferrocene (Fc) has been a fundamental compound in organ-ometallic chemistry and is still of important synthetic and analytic interest. Apart from its use as a reference redox system (Fc~+/Fc), chiral ferrocene-based ligands are one of the most important classes of auxiliaries in asymmetric homogeneous catalysis, and ferrocene-based polymeric materials have attracted intense interest with their unique physical and chemical features. The isolobal relationship between Cp~- and cyclo-P_5~- ligands, led to an enlarged understanding of the relations of such compounds, and the discovery of pentaphosphaferrocene can be regarded as a milestone in chemistry. Like ferrocene, the compound Cp*Fe(η~5-P5) (1) was subject of extensive reactivity studies towards organometallic reagents. Similarities are observed in the formation of triple-decker complexes or in Cplcyclo-P5-transfer reactions. Fragmentations and distortions of the cyclo-P5 ring of 1 were found to be significant differences between both compounds. Furthermore, the existence of lone pairs at the P atoms opened up an extensive coordination chemistry of the cyclo-P5 unit that led to 1D and 2D polymers' and spherical fullerene-like supramolecules.