IR SPECTROSCOPIC STUDY OF FERRICINIUM SALTS

Complex ferricinium salts, some not yet described in the literature, have been prepared by the oxidation of ferrocene. An ir study of these salts allowed the still dubious structure of the ferricinium cation to be unequivocally revealed. In the spectral region 4000 to 500 cm-1, all these compounds have but four intense bands, and it therefore follows that their cyclopentadienyl rings conform, to a D5th symmetry and that there is no coupling of vibrations between them. This, and their chemical composition, support the view that the valencies of the central iron atom are directed tetrahedrally and therefore, in contradistinction to ferrocene, the planes of the cyclopentadienyl rings are not parallel. © 1969.