Mössbauer spectra of alkali tris(maleato) ferrates(III), i.e., M3[Fe(C2H2C2O4)3]·nH2O [M=Li, Na, K, Cs] at 300 K display a doublet. The Mössbauer parameters indicate these complexes to be high spin with octahedral
symmetry. The isomer shift shows a decreasing trend with the increase in electronegativity/polarizing power of the substituent
cation (Li+, Na+, K+, Cs+). A linear correlation between isomer shift values and the (Fe−O) stretching frequencies has also been observed.