New penta-nuclear and hepta-nuclear iron(II, III) complexes with ferrocenedicarboxylic acid

The reaction of [Fe3EuO2(O2CCCl3)8(H2O)(THF)3] or [Fe2CaO(O2CCCl3)6(THF)4] and [Fe3O(O2CCMe3)6(H2O)3]NO3 with 1,1′-ferrocenedicarboxylic acid (fcdcH2) yielded penta- and hepta-nuclear [Fe4O2(O2CCCl3)6(fcdc)(THF)2(H2O)2] and [Fe6O2(OH)2(O2CCMe3)10(fcdc)(H2O)2], respectively, which are the first X-ray structurally characterized clusters comprising Fe(III) and the ferrocenedicarboxylic organometallic ligand. Variable-temperature solid-state magnetic susceptibility measurements in the temperature range 1.8–300 K were carried out, and for both complexes a predominantly antiferromagnetic exchange interaction between the metal centres was observed. Mössbauer investigations show the presence of different environments for the Fe(III) atoms and confirm that no electron-transfer from Fe(II) of the ferrocene unit to Fe(III) of the central core occurs.

Graphical abstractReaction of preformed iron clusters with 1,1′-ferrocenedicarboxylic acid (fcdcH2) yielded penta- and hepta-nuclear [Fe4O2(O2CCCl3)6(fcdc)(THF)2(H2O)2] and [Fe6O2(OH)2(O2CCMe3)10(fcdc)(H2O)2], respectively, which are the first clusters comprising FeIII and the ferrocenedicarboxylic organometallic ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide