Synthesis, structure and magnetic properties of organic-intercalated bimetallic molecular-based ferrimagnets (n-CnH2n+1)PPh3MIIFeIII(C2O4)3, (MII = Mn, Fe; n = 3–7)

Bimetallic tris-oxalato-salts (n-CnH2n+1)PPh3MIIFeIII(C2O4)3 (n = 3–7, MII = Mn, Fe) were prepared and the structures investigated by powder X-ray diffraction in order to study the evolution of the structure and magnetic properties as a function of alkyl chain length. The compounds all have the same two-dimensional honeycomb structure of MII and FeIII bridged by oxalate, with the organic cations lying between the metal–oxalate layers, whose separation ranges from 9.48 Å (n = 3) to 11.10 Å (n = 7) for the FeII salts and 9.37 to 10.81 Å for MnII. The compounds all behave as ferrimagnets, with magnetic parameters similar to the corresponding AMIIFeIII(C2O4)3 with A = NR4+, PPh4+ and Tcs almost insensitive to interlayer separation. The MnII salts exhibit uncompensated magnetisation below Tc and the FeII ones show Néel type N ferrimagnetism, with negative magnetisation at low temperature, the magnitude of which is influenced by the preparation conditions, due to vacancies in the FeII sublattice.