The redox behaviour of the dimeric tetrairon complex, ([fc(NPiPr2)2]Fe)2 (where fc(NPiPr2)2 = 1,1′-(C5H4NPiPr2)2Fe) has been investigated. Upon reduction with KC8 an Fe–Fe bond is formed with the complex maintaining a high spin configuration and having the formula [K(THF)6]([fc(NPiPr2)2]Fe)2. In contrast, oxidation of the complex is ligand based; for example, addition of the 1,2-diiodoethane (I2 equivalent) results in the formation of the monomeric iron(II) diiodide [fc(NiPr2I)2]FeI2 wherein the phosphine is oxidized. The dimeric tetrairon complex reacts photolytically with azobenzene, cleaving the N![[double bond, length as m-dash]](http://www.rsc.org/images/entities/char_e001.gif)
N double bond and forming the new monomeric bis(phosphoramidate) iron complex. [fc(NP(NPh)iPr2)2]Fe. Characterization of these paramagnetic complexes was accomplished by magnetic susceptibility studies and X-ray analyses.
![Graphical abstract: Redox behaviour of ([fc(NPiPr2)2]Fe)2, formation of an iron–iron bond and cleavage of azobenzene](http://hg.y866.cn/compound/lib/scimg/usr/1/C8DT00828K.jpg)
