Interpenetrated three-dimensional MnIIMIII ferrimagnets, [Mn(4dmap)4]3[M(CN)6]2•10H2O(M=Cr, Mn):: Structures, magnetic properties, and pressure-responsive magnetic modulation

Two novel cyanide-bridged ferrimagnets, [Mn(4dmap)(4)](3)[M(CN)(6)](2)- center dot 10H(2)O (4dmap=4-dimethylaminopyridine, M = Cr (1) and Mn (2)), have been prepared from the reaction of MnCl2 center dot 4H(2)O, a monodentate coligand (4dmap), with K-3[M(CN)(6)]. X-ray crystallographic results show that these are isomorphous, and form a unique twofold interpenetrated three-dimensional framework with a triconnected 6.10(2) net. The framework contains two types of one-dimensional channel: hexagonal channels based on a cyanide-bridged Mn6M6 hexagon, and triangle channels segmented by CN-Mn-NC linkages, which are filled with lattice water molecules. The dimethylamino groups of the 4dmap coligands are located around a pore and form the basic inner space. Variable-temperature X-ray powder diffraction and thermogravimetric analysis results show that the frameworks of both compounds are susceptible to dehydration through the loss of strongly hydrogen-bonded lattice water molecules. Magnetic measurements on both compounds show a ferrimagnetic ordering occurs at low temperature, Tc = 17 K for 1 and 6 K for 2. Application of hydrostatic pressure showed a positive effect on the magnetic ordering. Both values of T. increased linearly, to 25 K for 1 and 15 K for 2 at 1.0 GPa. The magnetic properties of both compounds were reversibly modulated by the external stress.