Synthesis, structure, and properties of 1,1′-diamino- and 1,1′-diazidoferrocene

We report an improved synthesis of 1, 1'-diaminoferrocene, employing the reduction of 1,1'diazidoferrocene with H-2-Pd/C, along with extensive characterization data for both compounds. Diaminoferrocene undergoes a reversible 1e(-) oxidation in CH3CN at a potential of -602 mV us Fc(0/+), 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 c-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.