Moessbauer Spectroscopic Study of Magnetic Ordering in Oxalate-Bridged Cr(III)-Fe(II) and Fe(III)-Fe(II) Systems

Magnetic ordering phenomena in mixed-metal assemblies {NBu4[Fe(II)M(III)(ox)3]}3∞ (M=Cr (1), Fe (2)) were studied by using 57Fe Moessbauer spectroscopy, where NBu4 +=tetra(n-butyl)ammonium ion, ox2-=oxalate ion. Nuclear Zeeman splittings were observed in the Moessbauer spectra of both 1 and 2 at low temperatures (below 10 K for 1 and 41 K for 2), which indicated the occurrence of three-dimensional magnetic ordering in these complexes under zero applied field.