Mononuclear Fe(III) Schiff Base Complex with Trans-FeO4N2 Chromophore of o-Aminophenol Origin: Synthesis, Characterisation, Crystal Structure, and Spin State Investigation

A new iron(III) complex (Et${}_3$NH)${}_2$[Fe(L)${}_2$](ClO${}_4$)·MeOH (1) where
H${}_2$L = 2-{(E)-[2-hydroxyphenyl)imino]methyl}phenol has been synthesised and characterised by
single crystal XRD, elemental analysis and DC magnetic susceptibility measurements. The dianionic
ligands L${}^2$− coordinate in a tridentate fashion with the Fe(III) through their deprotonated pheno-
lic oxygens and azomethine nitrogen atoms, resulting in a trans-FeO${}_4$N${}_2$ chromophore. Variable-
temperature magnetic measurements were performed between 300 and 5 K under an applied field of
0.1 T and show that 1 is in the high spin state (S = 5/2) over the whole measured temperature range.
This is confirmed by Mössbauer spectroscopy at 77 and 300 K.