Spin-glass behavior and magnetic splitting in molecular magnetic materials {[N(n-C 4 H 9 ) 4 ][M II Fe III (C 2 O 4 ) 3 ]} n (M = Co, Mn)

The mixed valence character and the antiferromagnetic coupling in the molecular magnetic materials {[N(n-C 4 H 9 ) 4 ][M II Fe III (C 2 O 4 ) 3 ]} n (M = Co, Mn) were investigated by Mössbauer spectroscopy and magnetic measurements. In the material {[N(n-C 4 H 9 ) 4 ][CoFe(C 2 O 4 ) 3 ]} n , the appearence of the spin-glass phase transition temperature and the magnetic phase transition under zero-field-cooled AC magnetic measurements were studied in the temperature range 5–100 K. In the Mössbauer spectra of {[N(n-C 4 H 9 ) 4 ][MnFe(C 2 O 4 ) 3 ]} a magnetic splitting was observed below 30 K. The appearance of the magnetic splitting indicates the occurrence of magnetic ordering in this complex. The hyperfine parameters show that the electronic state of iron is high-spin Fe 3+ .