Synthesis, structure and properties of 1,1'-diamino- and1,1'-diazidoferrocene

We report an improved synthesis of 1,1'-diaminoferrocene, employing the reduction of 1,1'-diazidoferrocene with H2-Pd/C, along with extensive characterization data for both compounds. Diaminoferrocene under goes a reversible 1e- oxidation in CH3CN at a potential of -602 mVvs Fc0/+, one of the most negative redox potentials for a ferrocene derivative. The chemical reversibility of this process was confirmed by isolation of the stable, 17-electron[Fc(NH2)2]+ cation as PF6-, OTf-, and TCNE-salts. In the solid state, diaminoferrocene exists in two conformations: one with the NH2 groups eclipsed, and the other with the NH2 groups offset by one-fifth turn around the Cp-Fe-Cp axis. Diazidoferrocene, on the other hand, exhibits only the fully eclipsed conformation in the solid state. The Fe-Cp (centroid) vectors in the diazidoferrocene molecules are roughly aligned with the crystallographic-axis, and the molecules form layers perpendicular to this axis. The compound is thermally unstable at elevated temperatures, and rapid heating above its melting point results in explosion.