Reinvestigation of structural and magnetic properties of a cyano-bridged bimetallic compound: K2Mn3(H2O)6[ Mo(CN)7] 2$\cdot $6H2O

In this communication, we reinvestigate the structural and magnetic properties of the title compound K2Mn3(H2O)6[ Mo(CN)7] $_{2}\cdot $6H2O. We show that this material crystallises in the space group $C2/c$(monoclinic no.15), instead of $C2$(monoclinic no.5) reported by J. Larianova et al.in J. Am. Chem. Soc., 121(1999) 3349 - 3356. The C2/c and C2 unit cells are closely related. The presence of an inversion center in the C2/c unit cell implies the doubling of the cparameter in comparison to the $C2$unit cell. Magnetic measurements show a transition from a paramagnetic state to a ferrimagnetic ordered state at 39 K, in agreement to neutron diffraction experiments. Key words.X-ray diffraction – Ferrimagnet – Heptacyanomolybdenate.