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

The crystal structure and magnetic properties of the molecular-based ferrimagnet N(n-C5H11)(4)(MnFeIII)-Fe-II(C2O4)(3) have been determined. The compound is orthorhombic, space group C222(1), a = 9.707(3), b = 16.140(3), c = 19.883(7) Angstrom (120 K), Z = 4 [R 0.047 for I > 2 sigma(1)]. The structure consists of hexagonal layers of alternating Mn-II and Fe-III 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 3d(5) configuration with (6)A(1) 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 x 10(-5) mu(B) atom(-1) arises, the direction of which was identified as parallel to the c axis by single-crystal magnetization measurements.