MOSSBAUER SPECTROSCOPIC STUDIES OF (NR4FEFE(OX)(3))(X) AND RELATED-COMPOUNDS (R = N-C3H7, N-C4H9)

Oxalate-bridged metal complexes, {NBu4[FeFe(ox)(3)]}(x) (1), {NPr4[FeF e(ox)(3)]}(x) (2), {NPr4[FeCr(ox)(3)]}(x) (3) and Fe-57(II)-doped {NPr 4[MnCr(ox)(3)]}(x) (4) were investigated by using Fe-57 Mossbauer spec troscopy, where NBu4+, NPr4+ and ox(2-) are the tetra(n-butyl)ammonium ion, tetra(n-propyl)ammonium ion and oxalate ion, respectively. Magne tically split features of the Mossbauer spectra of 1 and 2 below Neel temperature were similar to each other, while a great difference in ma gnetization behavior between these compounds was reported. From the te mperature dependence of the quadrupole splitting in the paramagnetic s tates, it was suggested that the axial field splitting of the t(2g) or bitals of Fe(II) is somewhat larger in 1 than in 2. The direction of t he internal field at Fe(II) was observed to be approximately parallel in 1-3 and perpendicular in 4 to the honeycomb layers consisting of an alternate array of the bivalent and tervalent metal ions through ox(2 -) ligands.