5 research outputs found
Cyano-Bridged Dy(III) and Ho(III) Complexes with Square-Wave Structure of the Chains
Four new cyano-bridged DyIII-CrIII, DyIII-FeIII, HoIII-CrIII and HoIII-FeIII bimetallic coordination polymers were synthesized by the reaction of [Ln(H2dapsc)(H2O)4](NO3)3 (Ln = Dy, Ho); H2dapsc = 2,6-diacetylpyridinebis(semicarbazone)) with K3[M(CN)6] (M = Cr, Fe) in H2O, resulting in the substitution of two water molecules in the coordination sphere of rare earth by paramagnetic tricharged hexacyanides of Fe and Cr. The complexes are isostructural and consist of alternating [Ln(H2dapsc)(H2O)2]3+ and [M(CN)6]3− units linked by bridges of two cis-cyano ligands of the anion to form square-wave chains. The ac magnetic measurements revealed that the DyCr and DyFe complexes are field-induced single molecule magnets, while their Ho analogs do not exhibit slow magnetic relaxation
Synthesis, Structure, and Magnetic Properties of 1D {[Mn<sup>III</sup>(CN)<sub>6</sub>][Mn<sup>II</sup>(dapsc)]}<sub><i>n</i></sub> Coordination Polymers: Origin of Unconventional Single-Chain Magnet Behavior
Two one-dimensional
cyano-bridged coordination polymers, namely,
{[Mn<sup>II</sup>(dapsc)]Â[Mn<sup>III</sup>(CN)<sub>6</sub>]Â[KÂ(H<sub>2</sub>O)<sub>2.75</sub>(MeOH)<sub>0.5</sub>]}<sub><i>n</i></sub>·0.5<i>n</i>(H<sub>2</sub>O) (<b>I</b>) and {[Mn<sup>II</sup>(dapsc)]Â[Mn<sup>III</sup>(CN)<sub>6</sub>]Â[KÂ(H<sub>2</sub>O)<sub>2</sub>(MeOH)<sub>2</sub>]}<sub><i>n</i></sub> (<b>II</b>), based on alternating high-spin
Mn<sup>II</sup>(dapsc) (dapsc = 2,6-diacetylpyridine bisÂ(semicarbazone))
complexes and low-spin orbitally degenerate hexacyanomanganateÂ(III)
complexes were synthesized and characterized structurally and magnetically.
Static and dynamic magnetic measurements reveal a single-chain magnet
(SCM) behavior of <b>I</b> with an energy barrier of <i>U</i><sub>eff</sub> ≈ 40 K. Magnetic properties of <b>I</b> are analyzed in detail in terms of a microscopic theory.
It is shown that compound <b>I</b> refers to a peculiar case
of SCM that does not fall into the usual Ising and Heisenberg limits
due to unconventional character of the Mn<sup>III</sup>–CN–Mn<sup>II</sup> spin coupling resulting from a nonmagnetic singlet ground
state of orbitally degenerate complexes [Mn<sup>III</sup>(CN)<sub>6</sub>]<sup>3–</sup>. The prospects of [Mn<sup>III</sup>(CN)<sub>6</sub>]<sup>3–</sup> complex as magnetically anisotropic
molecular building block for engineering molecular magnets are critically
analyzed
Single-Ion Magnet Et<sub>4</sub>N[Co<sup>II</sup>(hfac)<sub>3</sub>] with Nonuniaxial Anisotropy: Synthesis, Experimental Characterization, and Theoretical Modeling
In
this article we report the synthesis and structure of the new
CoÂ(II) complex Et<sub>4</sub>NÂ[Co<sup>II</sup>Â(hfac)<sub>3</sub>] (<b>I</b>) (hfac = hexafluoroacetylacetonate) exhibiting
single-ion magnet (SIM) behavior. The performed analysis of the magnetic
characteristics based on the complementary experimental techniques
such as static and dynamic magnetic measurements, electron paramagnetic
resonance spectroscopy in conjunction with the theoretical modeling
(parametric Hamiltonian and ab initio calculations) demonstrates that
the SIM properties of <b>I</b> arise from the nonuniaxial magnetic
anisotropy with strong positive axial and significant rhombic contributions