Two new preparative routes to, and 57Fe Mössbauer and infrared spectroscopic measurements on, the salts of µ-halogeno-bis[(π-cyclopentadienyl)dicarbonyliron(II)] cations, [(π-C5H5)Fe(Co)2]2X+(halogeno = chloro, bromo, or iodo)

Abstract

The [(π-C₅H₅)Fe(CO)₂]₂X⁺PF₆^– salts can be prepared from the corresponding (π-C₅H₅)Fe(CO)₂X complexes (X = Cl, Br, or I) either by reaction with sulphuric acid and subsequent treatment with hexafluorophosphoric acid, or by treatment with silver hexafluorophosphate. The structures of the [(π-C₅H₅)Fe(CO)₂]₂X⁺ cations are discussed in terms of their ⁵⁷Fe Mössbauer and i.r. spectra; u.v.–visible spectra are also reported for the complexes.