Alkali counterions tune diruthenium(iii,iii)-based ferrimagnetic chain structured antiferromagnets exhibiting step-like hysteresis loops

Homo-valent diruthenium(II,II) carbonates Na4[Ru2(CO3)4]·10H2O: synthesis, structure, properties, and calculation

Homo-valent diruthenium(II,II) carbonates have been underexplored hitherto. This paper reports the synthesis and crystal structure of a diruthenium(II,II) compound, Na₄Ru₂(CO₃)₄·10H₂O (1). It has a two-dimensional structure in which the paddle-wheel diruthenium units of Ru₂(CO₃)₄^4- are cross-linked through the carbonate groups. The investigation of the primary magnetic properties and theoretical studies with density functional theory (DFT) reveal that weak antiferromagnetic interactions are propagated between the Ru₂ units which contain two unpaired electrons in an electron configuration σ²π⁴δ²π*²δ*² with a ground state S = 1. According to Raman spectrum measurements combined with theoretical calculations, the strong peak at 356 cm^-1 in the small-wavenumber region was assigned to the stretching of the Ru-Ru double bonds.

Synthesis, crystal structure and magnetic properties of a one-dimensional Mn2+ complex constructed from (+)-dibenzoyltartaric acid and 2,2'-bipyridine

The self-assembly reaction of (+)-dibenzoyltartaric acid (D-H₂DBTA) with 2,2'-bipyridine (bpy) and Mn(CH₃CO₂)₂·4H₂O yielded a new coordination polymer, namely, catena-poly[[[diaqua(2,2'-bipyridine-κ²N,N')manganese(II)]-μ-2,3-bis(benzoyloxy)butanedioato-κ²O²:O³] dihydrate], {[Mn(C₁₈H₁₂O₈)(C₁₀H₈N₂)(H₂O)₂]·2H₂O}_n or {[Mn(DBTA)(bpy)(H₂O)₂]·2H₂O}_n, (I). Complex (I) has been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA) and single-crystal and powder X-ray diffraction. It crystallizes in the orthorhombic space group P2₁2₁2₁. In the complex, the Mn²⁺ cation displays a distorted octahedral {MnO₄N₂} geometry, formed from two carboxylate O atoms of two DBTA^2- ligands, two cis-oriented N atoms from one chelating 2,2'-bipyridine ligand and two trans-oriented O atoms from coordinated water molecules. The polymer displays a 1D chain with an Mn...Mn distance of 9.428 (1) Å. Due to the presence of flexible polycarboxylate and rigid bipyridyl ligands in the molecular structure, a high thermal stability of the complex is attained. The magnetic properties of (I) were analyzed based on the mononuclear Mn²⁺ model due to the long intramolecular Mn...Mn distance. The zero field splitting (ZFS) contribution in the high-spin Mn²⁺ cation is almost negligible and there are weak antiferromagnetic couplings between 1D chains [zJ' = -0.062 (5) cm^-1], corresponding to an intermolecular Mn...Mn distance of 7.860 (2) Å.

Interlayer hydrogen bonding directed magnetic properties for a different number of water-intercalated structural heterometallic phosphates based on paddlewheel units Ru2(PO4)46

Layered heterometallic phosphates {Mn(H2O)4}2Mn(H2O)2Ru2(PO4)4(H2O)2 (1) with a new topology were constructed from Ru2(PO4)46- and Mn2+ in the presence of anions as assisting reactants whose alkaline strength plays a key role in directing a different number of lattice water-intercalated structures. In the presence of CO32- and SO42- as assisting reactants, the assembling reaction in the aqueous solution at room temperature results in compounds 1·10H2O and 1·4H2O, respectively. Single-crystal X-ray diffraction analysis reveals that compounds 1·10H2O and 1·4H2O crystallize in orthorhombic space group Pbca and monoclinic space group P21/c, respectively. The layered structure of 1 is constructed by alternating Ru2O10 tetragonal dipyramid and MnO6 octahedra bridged by PO4 tetrahedra. The neutral heterometallic phosphate layers of 1 are separated by a different number of interlayer lattice water molecules, and hydrogen bonds are responsible for the neutral inorganic layer connection. Magnetism measurements show that compound 1·10H2O exhibits a soft magnet behaviour ordering below 8.5 K with indirect hydrogen bonding between these ferrimagnetic layers, and a reentrant spin-glass-like transition is observed for compound 1·4H2O, exhibiting two steps transition at 8.0 and 12 K, due to a strong competition between intralayer magnetic coupling and interlayer antiferromagnetic interactions mediated through the direct hydrogen bonding.

Structural diversity and magnetic properties of six ferrocenyl monocarboxylate Mn(ii), Ni(ii) and Co(ii) complexes with 1D aqua, carboxyl or dinuclear hydroxyl bridges

Six ferrocenyl monocarboxylate Mn(ii), Ni(ii) and Co(ii) complexes with different types of magnetic coupling bridges were synthesized successfully. 1–6 display intriguing structure diversity and magnetic properties.