The occurrence of a slow relaxation of the magnetization in a one-dimensional (1D) system was recently reported by one of us.[1] The system was claimed to illustrate, for the first time, a theoretical model designed by Glauber in 1963 for anisotropic Ising systems [2] and opened the perspective of a potential use of 1D magnetic molecular nanowires for information storage. Even though 1D magnetism is a very active area of research, such dynamic behavior was never detected before since it is not clear how to fulfill experimentally the requirements of a perfect 1D Ising-type chain. This finding prompted us to look carefully at 1D systems containing anisotropic elements, such as cobalt(ii) and low-spin iron(iii) centers that we synthesized recently, [3] to investigate their anisotropic magnetic properties and to study the dynamics of their magnetization.The stable low-spin cyanide-containing iron(iii) precur-À (L = bidentate nitrogen donor) react with hydrated metal ions in aqueous solution [4,5] and afford single crystals of the bimetallic double zigzag chains [{Fe(1 with L = 2,2'-bipyridine (bpy) and 2 with L = 1,10-phenanthroline (phen)). We found that 1 and 2 show intrachain ferromagnetic coupling, 1D Ising-type behavior, slow relaxation of the magnetization, and hysteresis effects and thus are the second examples of anisotropic molecular magnetic nanowires and the first with an intrachain ferromagnetic coupling. Their preparation, Xray crystal structure, [6] and preliminary static and dynamic magnetism are reported herein.Compounds 1 and 2 are isostructural (monoclinic system, space group P2 1 /n). They are made up of neutral cyanidebridged Co II

No abstract

The synthesis, crystal structure, and magnetic properties of [Cp2TiGi-OCH3)]2 (1) (Cp = tj5-C5H5) and [Cp2Ti-(m-OC2H5)]2 (2) are described. The two compounds are obtained from [Cp2Ti(CH3)2] and trimethoxy-and triethoxysilane, respectively, in hexane. Both crystallize in the tetragonal system, space group PAnl.

The synthesis, X-ray structures, and magnetic behavior of two new, three-dimensional compounds [W(IV)[(mu-CN)(4)Co(II)(H(2)O)(2)](2).4H(2)O](n) (1) and [[W(V)(CN)(2)](2)[(mu-CN)(4)Co(II)(H(2)O)(2)](3).4H(2)O](n) (2) are presented. Compound 1 crystallizes in the tetragonal system, space group I4/m with cell constants a = b = 11.710(3) A, c = 13.003(2) A, and Z = 4, whereas 2 crystallizes in the orthorhombic system, space group Cmca with cell constants a = 13.543(5) A, b = 16.054(6) A, c = 15.6301(9) A, and Z = 4. The structure of 1 shows alternating eight-coordinated W(IV) and six-coordinated Co(II) ions bridged by single cyanides in a three-dimensional network. The geometry of each [W(IV)(CN)(8)](4-) entity in 1 is close to a square antiprism. Its eight cyanide groups are coordinated to Co(II) ions which have two coordinated water molecules in trans position. The structure of 2 consists of alternating eight-coordinated W(V) and six-coordinated Co(II) ions linked by single cyanide bridges in a three-dimensional network. Each [W(V)(CN)(8)](3-) unit shows a geometry close to a square antiprism. Only six of its eight cyanide groups are coordinated to Co(II) ions while the other two are terminal. The Co(II) ion in 2 has the same CoN(4)O(2) environment as in 1. The magnetic behavior of 1 is that of magnetically isolated high spin Co(II) ions (S(Co) = 3/2), bridged by the diamagnetic [W(IV)(CN)(8)](3-) units (S(W(IV)) = 0). The magnetic behavior of 2, where the high spin Co(II) ions are bridged by the paramagnetic [W(V)(CN)(8)](3-) units [S(W(V)) = 1/2], is that of ferromagnetically coupled Co(II) and W(V) giving rise to an ordered ferromagnetic phase below 18 K. The magnetic properties of 1 are used as a blank to extract the parameters that are useful to analyze the magnetic data of compound 2.