Crystal structure and magnetic properties of the layer ferrimagnet N(n-C5H11)4MnIIFeIII(C2O4)3

Abstract

The crystal structure and magnetic properties of the molecular-based ferrimagnet N(n-C₅H₁₁)₄Mn^IIFe^III(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 Mn^II and Fe^III bridged by C₂O₄^2–, 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 C₂O₄^2–. 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 T_N= 27 K an uncompensated moment estimated as 8.78 × 10^–5µ_B atom^–1 arises, the direction of which was identified as parallel to the c axis by single-crystal magnetization measurements.