The crystal structures,molecular spectra and thermal behaviour of carbamoylferrocene and ferrocenecarbonylhydrazide

Carbamoylferrocene (1) and ferrocenecarbonylhydrazide (2) were synthesised by modified literature procedures and studied by a combination of the conventional spectroscopic methods (IR, MS and NMR), X-ray crystallography and thermal analysis. The crystal structures of two new polymorphs of amide 1 and the structure of hydrazide 2 were determined, revealing extensive hydrogen bonding interactions of the polar ferrocene substituents and supportive π?$?$π stacking interactions. Whereas the thermal behaviour of hydrazide 2 was relatively complicated, thermolysis of amide 1 in the presence of air oxygen led to a complete elimination of the organic constituents in a single step under mild conditions affording essentially pure hematite (α-Fe₂O₃). Mössbauer spectra, powder X-ray diffraction and high-resolution transmission electron microscopy indicated the pyrolytic hematite to result in the form of random aggregates of well crystalline nanoparticles.