Crystal structure and magnetic properties of the layer ferrimagnet N(n-C₅H₁₁)₄Mn^IIFe^III(C₂O₄)₃

Abstract

The crystal structure and magnetic properties of the molecular-based ferrimagnet N(n-C5H11)4MnIIFeIII(C2O4)3 have been determined. The compound is orthorhombic, space group C2221, a= 9.707(3), b= 16.140(3), c= 19.883(7)Å(120 K), Z= 4[R 0.047 for I > 2σ(I)]. The structure consists of hexagonal layers of alternating MnII and FeIII bridged by C2O42–, separated by layers containing only N(n-C5H11)4+ with the alkyl chains extended, though with the terminal bonds twisted towards the gauche conformation. The terminal CH3 are embedded in the hexagonal pockets formed by three C2O42–. Since both metal ions have 3d5 configuration with 6A1 ground states the magnetic properties in the paramagnetic region mimic those of a two-dimensional antiferromagnet. Below TN= 27 K an uncompensated moment estimated as 8.78 × 10–5µB atom–1 arises, the direction of which was identified as parallel to the c axis by single-crystal magnetization measurements.