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 [1; 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.

Spin-singlet Quantum Ground State in Zigzag Spin Ladder Cu(CF3 COO)2

The copper salt of trifluoroacetic acid, Cu(CF₃ COO)₂ , offers a new platform to investigate the quantum ground states of low-dimensional magnets. In practice, it realizes the ideal case of a solid hosting essentially isolated magnetic monolayers. These entities are constituted by well-separated two-leg half-integer spin ladders organized in a zigzag fashion. The ladders are comprised of dimeric units of edge-sharing tetragonal pyramids coupled through carbon ions. The spin-gap state in this compound was revealed by static and dynamic magnetic measurements. No indications of long range magnetic ordering down to liquid helium temperature were obtained in specific heat measurements. First principles calculations allow estimation of the main exchange interaction parameters, J_⊥ =176 K and J_∥ =12 K, consistent with the weakly interacting dimers model.

Crystal structure and spin-trimer magnetism of Rb2.3(H2O)0.8Mn3[B4P6O24(O,OH)2]

The novel borophosphate Rb_2.3(H₂O)_0.8Mn₃[B₄P₆O₂₄(O,OH)₂] was prepared under hydrothermal conditions at 553 K. Its crystal structure was determined using single-crystal X-ray diffraction data obtained from a non-merohedral twin and refined against F² to R = 0.057. The compound crystallizes in the orthorhombic space group Pbcn, with unit-cell parameters a = 20.076(2) Å, b = 9.151(1) Å, c = 12.257(1) Å, V = 2251.8(2) ų, and Z = 4. The title compound is the first example of a borophosphate with manganese ions adopting both octahedral and tetrahedral coordinations. Its unique crystal structure is formed by borophosphate slabs and chains of Mn²⁺-centered polyhedra sharing edges and vertices. These 2D and 1D fragments interconnect into a framework with open channels that accommodate Rb⁺ cations and water molecules. Topological relationships between borophosphates built from three-membered rings of two borate and one phosphate tetrahedra sharing oxygen vertices, amended by additional PO₄ and HPO₄ tetrahedra, are discussed. The temperature dependence of the magnetic susceptibility of Rb_2.3(H₂O)_0.8Mn₃[B₄P₆O₂₄(O,OH)₂] reveals predominant antiferromagnetic exchange interactions and the high-temperature effective magnetic moment corresponding to the high-spin S = 5/2 state of Mn²⁺ ions. At 12.5 K, a magnetic transition is evidenced by ac-susceptibility and specific heat measurements. A spin-trimer model with the leading exchange interaction J ∼ 3.2 K is derived from density-functional band-structure calculations and accounts for all experimental observations.

Evidence of field induced slow magnetic relaxation in cis-[Co(hfac)2(H2O)2] exhibiting tri-axial anisotropy with a negative axial component

We report a combined experimental characterization and theoretical modeling of the hexa-coordinated high-spin Co(ii) complex cis-[Co(hfac)₂(H₂O)₂] (I).