Crystalline, Mixed-Valence Manganese Analogue of Prussian Blue: Magnetic, Spectroscopic, X-ray and Neutron Diffraction Studies

The compound of stoichiometry Mn(II)3[Mn(III)(CN)6]2·zH2O (z = 12−16) (1) forms air-stable,
transparent red crystals. Low-temperature single crystal optical spectroscopy and single crystal X-ray
diffraction provide compelling evidence for N-bonded high-spin manganese(II), and C-bonded low-spin
manganese(III) ions arranged in a disordered, face-centered cubic lattice analogous to that of Prussian
Blue. X-ray and neutron diffraction show structured diffuse scattering indicative of partially correlated (rather
than random) substitutions of [Mn(III)(CN)6] ions by (H2O)6 clusters. Magnetic susceptibility measurements
and elastic neutron scattering experiments indicate a ferrimagnetic structure below the critical temperature
Tc = 35.5 K.