The 1′,1‴-diacetyl and 1′-acetyl-1‴-(1-naphthylimino-ethyl)substituted biferrocenes, CH3COFcFcCOCH3 (1) and CH3COFcFcC(CH3)Nnp (2), where Fc = C5H4FeC5H4 and np = 1-naphthyl, and the corresponding monocations as salts with I3−, I5−, FeCl4− and CuI2− have been prepared. The crystal structures of 1 and 2 have been determined. The temperature-dependent Mössbauer spectra of the biferrocenium salts with the exception of the I3− salt from 2 revealed them all to be of the mixed-valence type. The interaction between counter anions and the biferrocenium cations is discussed.
Journal of organometallic chemistry 470(1-2), pp.161-167