Magnetic transitions in the cyano-bridged bimetallic ferromagnet Mn-2(H2O)(5)Mo(CN)(7)center dot 4.75H(2)O (beta phase)

Slow diffusion of two aqueous solutions containing K-4[Mo(CN)(7)]. 2H(2)O a nd [Mn(H2O)(6)](NO3)(2), respectively, has afforded two kinds of single cry stals whose formulas are Mn-2(H2O)(5)Mo(CN)(7)]. 4H(2)O (alpha phase) and M n-2(H2O)(5)Mo(CN)(7)]. 4.75H(2)O (beta phase). This paper is devoted to the latter compound. It crystalizes in the monoclinic system, space group P2(1 )/c, a = 7.885(3) Angstrom, b = 10.406(7) Angstrom, c = 25.233(11) Angstrom , beta = 98.11(2)degrees, Z = 4. The Mo site is surrounded by seven -C-N-Mn linkages in a distorted pentagonal bipyramid fashion. There are two distor ted octahedral Mn sites, one with four and the other with three -N-C-Mo lin kages. The structure is three-dimensional. It consists of bent ladders made of edge-sharing (MoCNMnNC)(2) lozenge motifs running along the a direction . These ladders are linked further along the a and c directions. The a, b, and c* axes were determined to be the magnetic axes; Both temperature and f ield dependence of the magnetization have been measured along the magnetic axes. The angular dependence of the magnetization in the ab plane as a func tion of the external field has also been measured. Single crystal magnetic measurements revealed that the compound orders ferromagnetically at T-c = 5 1 K, without a hysteresis effect. They have also shown that the compound ha s a complex magnetic phase diagram when the field is applied along the a di rection, with several ferromagnetically ordered domains and a spin reorient ation domain. The boundaries between these domains have been determined. Th ese results have been compared to those obtained with Mn-2(H2O)(5)Mo(CN)(7) ]. 4H(2)O (alpha phase).