Structures, ferromagnetic ordering, anisotropy, and spin reorientation fortwo- and three-dimensional cyano-bridged Mo3+-Mn2+ compounds

The compounds K2Mn3(H2O)(6)[Mo(CN)(7)](2). 6H(2)O and Mn-2(H2O)(5)Mo(CN)(7) . nH(2)O (alpha phase, n = 4; beta phase, n = 4.75) have been synthesized i n the form of well shaped single crystals by slow diffusion of aqueous solu tions containing [Mo(CN)(7)]K-2. 2H(2)O and [Mn(H2O)(6)](NO3), respectively . The first compound has been obtained in the presence of an excess of K+ i ons. The crystal structures have been determined. K2Mn3(H2O)(6)[Mo(CN)(7)]( 2). 6H(2)O is two-dimensional, and Mn-2(H2O)(5)Mo(CN)(7). nH(2)O (alpha and beta phases) are three-dimensional. The magnetic properties have been stud ied in great detail through single crystal magnetic measurements, and the m agnetic phase diagrams have been determined. The three compounds exhibit a long-range ferromagnetic ordering along with a field-induced spin reorienta tion. Furthermore, the last two compounds show an additional magnetically o rdered state which disappears when applying a sufficiently large magnetic f ield. The magnetic properties have been found to be dramatically modified w hen the non-coordinated water molecules are released. For instance, T-c is shifted from 39 to 72 K for K2Mn3(H2O)(6)[Mo(CN)(7)](2). 6H(2)O, and a pron ounced coercivity is observed after partial dehydration.