Uncompensated magnetization in the layered molecular antiferromagnet {N(n-C5H11)4[MnIIFeIII(ox)3]}∞

The honeycomb layered {N(n-C5H11)4[MnIIFeIII(ox)3]}∞ antiferromagnet, where both MnII and FeIII ions have spin S=5/2, shows anisotropy and an uncompensated moment below TN of 27K. The Mössbauer spectrum in the applied magnetic field reveals the presence of two FeIIIA and FeIIIB spin sites with different responses towards the external magnetic field that is most probably responsible for the uncompensated magnetization. Breaking the local symmetry of the FeIII sites by the bulky N(n-C5H11)4 cations together with a small difference in g-factors for MnII and FeIII ions and a relatively large zero-field splitting for MnII may be a reason for the two non-equivalent sites within the iron sub-lattice.