Synthesis, Structure, and Magnetic Properties of 1D {[Mn^III(CN)₆][Mn^II(dapsc)]}_<i>n</i> Coordination Polymers: Origin of Unconventional Single-Chain Magnet Behavior

Two one-dimensional cyano-bridged coordination polymers, namely, {[Mn^II(dapsc)]­[Mn^III(CN)₆]­[K­(H₂O)_2.75(MeOH)_0.5]}_<i>n</i>·0.5<i>n</i>(H₂O) (<b>I</b>) and {[Mn^II(dapsc)]­[Mn^III(CN)₆]­[K­(H₂O)₂(MeOH)₂]}_<i>n</i> (<b>II</b>), based on alternating high-spin Mn^II(dapsc) (dapsc = 2,6-diacetylpyridine bis­(semicarbazone)) complexes and low-spin orbitally degenerate hexacyanomanganate­(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>_eff ≈ 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^III–CN–Mn^II spin coupling resulting from a nonmagnetic singlet ground state of orbitally degenerate complexes [Mn^III(CN)₆]^3–. The prospects of [Mn^III(CN)₆]^3– complex as magnetically anisotropic molecular building block for engineering molecular magnets are critically analyzed

Multifunctional Compound Combining Conductivity and Single-Molecule Magnetism in the Same Temperature Range

We report the first highly conducting single-molecule magnet, (BEDO)₄[ReF₆]·6H₂O [<b>1</b>; BEDO = bis­(ethylenedioxo)­tetrathiafulvalene], whose conductivity and single-molecule magnetism coexist in the same temperature range. The compound was synthesized by BEDO electrocrystallization in the presence of (Ph₄P)₂[ReF₆]·2H₂O and characterized by crystallography and measurements of the conductivity and alternating-current magnetic susceptibility

The Conducting Spin-Crossover Compound Combining Fe(II) Cation Complex with TCNQ in a Fractional Reduction State

The radical anion salt [Fe­{HC­(pz)₃}₂]­(TCNQ)₃ demonstrates conductivity and spin-crossover (SCO) transition associated with Fe­(II) complex cation subsystem. It was synthesized and structurally characterized at temperatures 100, 300, 400, and 450 K. The compound demonstrates unusual for 7,7,8,8,-tetracyanoquinodimethane (TCNQ)-based salts quasi-two-dimensional conductivity. Pronounced changes of the in-plane direct-current resistivity and intensity of the electron paramagnetic resonance (EPR) signal, originated from TCNQ subsystem, precede the SCO transition at the midpoint <i>T</i>* = 445 K. The boltzmannian growth of the total magnetic response and structural changes in the vicinity of <i>T</i>* uniquely show that half [Fe­{HC­(pz)₃}₂] cations exist in high-spin state. Robust broadening of the EPR signal triggered by the SCO transition is interpreted in terms of cross relaxation between the TCNQ and Fe­(II) spin subsystems