Antiferromagnetic Ordering of Mn(III)F(salen)

Due to a report suggesting Mn(III)F(salen), salen = H$_{14}$C$_{16}$N$_2$O$_2$, is an $S = 2$ Haldane system with $J/k_B = 50$~K and no long-range order down to 2~K based on standard magnetometry studies,\footnote{T.~Birk \emph{et al.}, Inorg.~Chem.~{\bf50} (2011) 5312.} specific heat and NMR measurements were performed. Using small single crystals, specific heat studies revealed the presence of an anomaly near 23~K, and this response was robust in fields up to 9~T. The $^1$H NMR results performed on a single crystal in 1~T revealed a sharp transition characteristic of antiferromagnetic ordering at 22.5~K. Measuring the magnetic response of the same single crystal in a commercial magnetometer reveals the presence of a subtle feature, near 23~K, that is not resolved with as-grown, randomlly oriented microcrystalline samples. These findings provide insight into the results obtained in torque magnetometry, EPR, and neutron scattering data.\footnote{J.-H.~Park \emph{et al.}, Acta Phys.~Pol.~A, in press.}