3 nm-wide Cyanometallate Fe-Co Tape Exhibiting Single-Chain Magnet Behavior

Treatment of Co(OTf)2·6H2O, Li[(pzTp)FeIII(CN)3], and H3PMo12O40·nH2O in protic solvents afforded two structurally related Fe-Co cyanometallate complexes: [{(pzTp)Fe(CN)3}3Co3(MeOH)10][PMo12O40]·H2O·11MeOH (1, pzTp- = tetra(pyrazolyl)borate) and {[(pzTp)Fe(CN)3]4Co3(MeOH)5(H2O)3}n[HPMo12O40]n·3 nMeOH·6.5nH2O (2). Complex 1 consists of a cyanide-bridged hexanuclear [Fe3Co3] cage, characterized by the fused conjunction of two mutually perpendicular trigonal bipyramids (TBPs, [Fe2Co3] and [Co2Fe3]), while complex 2 showcases an intricate cyanide-bridged Fe-Co tape comprising a central chain backbone of vertex-sharing [Fe2Co3] TBPs alongside peripheral [Fe2Co2] squares. Complex 2 is among the widest one-dimensional coordination assemblies characterized by the single-crystal X-ray diffraction technique. Magnetic studies revealed that complex 2 behaved as a single chain magnet with an effective energy barrier (Ueff/kB) of 46.8 K. Our findings highlight the possibilities in the development of cyanometallate-POM hybrid materials with captivating magnetic properties.

Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry

The magnetic anisotropy associated with a pentagonal bipyramidal (PBP) coordination sphere is examined on the basis of experimental and theoretical investigations. The origin and the characteristics of this anisotropy are discussed in relation to the electronic configuration of the metal ions. The effects of crystal field, structural distortion, and a second-coordination sphere on the observed anisotropies for transition meal and lanthanide ions are outlined. For the Ln derivatives, we focus on compounds showing SMM-like behavior (i.e. slow relaxation of their magnetization) in order to highlight the essential chemical and structural parameters for achieving strong axial anisotropy. The use of PBP complexes to impart controlled magnetic anisotropy in polynuclear species such as SMMs or SCMs is also addressed. This review of the magnetic anisotropies associated with a pentagonal bipyramidal coordination sphere for transition metal and lanthanide ions is intended to highlight some general trends that can guide chemists towards designing a compound with specific properties.

Accessing water processable cyanido bridged chiral heterobimetallic Co(ii)-Fe(iii) one dimensional network

A water processable cyanido bridged extended chiral heterobimetallic Co(ii)-Fe(iii) network is assembled. The unusual water processability of the coordination polymer originates from dangling hydrophilic substituents. The present approach offers a simple route to impart solution processability to cyanido bridged molecular magnetic materials.

Heterometallic MIILnIII (M = Co/Zn; Ln = Dy/Y) Complexes with Pentagonal Bipyramidal 3d Centers: Syntheses, Structures, and Magnetic Properties

We herein reported the syntheses, structures, and magnetic properties of three dinuclear heterometallic M^IILn^III complexes, namely, [M^IILn^III(H₂L)(CH₃OH)₂(NO₃)₂](NO₃)·S (M = Co, Ln = Dy, S = MeOH (1_CoDy); M = Zn, Ln = Dy, S = MeOH (2_ZnDy); M = Co, Ln = Y, S = MeNO₂ (3_CoY), H₄L = 2,6-diacetylpyridine bis[2-(semicarbazono) propionylhydrazone]. Synthesized from the predesigned multidentate ligand H₄L, which has two different coordination pockets (smaller N₃O₂ and larger N₂O₄ pockets) suitable for either a 3d or a 4f metal center, all these complexes have very similar structures, where the M^II centers possess a pentagonal bipyramidal (PBP) geometry and the Ln^III sites have a tetradecahedron geometry. Magnetic measurements on these compounds revealed the existence of weak ferromagnetic coupling between the Co²⁺ and Dy³⁺ centers and the field-induced slow magnetic relaxation of all three complexes. Furthermore, theoretical calculation on all these complexes indicates that although the change of the diamagnetic Zn²⁺ ion to the paramagnetic Co²⁺ ion only slightly modifies the local magnetic anisotropy of the Dy³⁺ ion, the weak Co-Dy magnetic interaction decreases the energy barrier. These compounds are the first systematic results of a heterometallic 3d-4f single-molecule magnet containing predesigned PBP 3d metal ions.

A cyano-bridged coordination nanotube showing field-induced slow magnetic relaxation

Field-induced slow magnetic relaxation was observed in a cyano-bridged nanotube constructed from a pentagonal bipyramidal Co^II unit and a hexacyanocobaltate(iii) anion.

Two-dimensional frameworks formed by pentagonal bipyramidal cobalt(ii) ions and hexacyanometallates: antiferromagnetic ordering, metamagnetism and slow magnetic relaxation

Two-dimensional frameworks constructed by pentagonal bipyramidal Co^II and [M(CN)₆]³⁻ units have been synthesized and characterized structurally and magnetically.