Structural and Magnetic Diversity in Cyano-Bridged Bi- and Trimetallic Complexes Assembled from Cyanometalates and [M(rac-CTH)]n+ Building Blocks (CTH = d,l-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane)

Heterobimetallic cyanide-bridged FeIII(μ-CN)MII complexes (M = Mn and Cu): synthesis, structure and magnetism

Systematic magneto-structural studies reveal ‘[FeIII(Tp)(CN)2(μ-CN)MnIICl(L1/L2)]′ (both antiferromagnetic) and [FeIII(Tp)(CN)2(μ-CN)CuII(L1/L2)]+′(L1 ferro- and L2 antiferromagnetic).

A rare isostructural series of 3d-4f cyanido-bridged heterometallic squares obtained by assembling [FeIII{HB(pz)3}(CN)3]- and LnIII ions: synthesis, X-ray structure and cryomagnetic study

A new series of cyanido-bridged {Fe^IIILn^III}₂ neutral molecular squares of general formula [Fe{HB(pz)₃}(CN)(μ-CN)₂Ln(NO₃)₂(pyim)(Ph₃PO)]₂·2CH₃CN [Ln = Ce (1), Pr (2), Nd (3), Gd (4), Tb (5), Dy (6) and Er (7); {HB(pz)₃}^- = hydrotris(pyrazolyl)borate, pyim = 2-(1H-imidazol-2-yl)pyridine and Ph₃PO = triphenylphosphine oxide] were obtained by reacting the low-spin [Fe{HB(pz)₃}(CN)₃]^- species with the preformed [Ln^III(pyim)(NO₃)₂(pyim)(Ph₃PO)]⁺ complex anions (generated in situ by mixing the nitrate salt of each Ln(III) ion with pyim and Ph₃PO molecules). Single-crystal X-ray diffraction studies show that 1-7 are isostructural compounds that crystallize in the triclinic P1̄ space group. Their crystal structures consist of centrosymmetric cyanido-bridged {Fe^IIILn^III}₂ molecular squares where two [Fe{HB(pz)₃}(CN)₃]^- units adopt bis-monodentate coordination modes towards two [Ln^III(pyim)(NO₃)₂(pyim)(Ph₃PO)]⁺ moieties. The cis-oriented convergent sites from both low-spin Fe^III and Ln^III fragments form a quasi square-shaped molecule in which the 3d and 4f ions alternatively occupy the corners of the square. Both Fe^III ions show a distorted octahedral surrounding (C_3v symmetry), whereas the Ln^III ions exhibit a distorted muffin-like geometry (C_s symmetry) in 1-7. The intramolecular Fe^III⋯Ln^III distances across the two cyanido-bridges range from ca. 5.48/5.46 up to ca. 5.58/5.61 Å. The molecular squares in 1-7 are interlinked through hydrogen bonds, weak π⋯π stacking and very weak C-H⋯π type interactions into three-dimensional supramolecular networks. The analysis of the solid-state direct-current (dc) magnetic susceptibility data of 1-7 in the temperature range 1.9-300 K reveals the occurrence of weak intra- and intermolecular antiferromagnetic interactions. The small intramolecular antiferromagnetic couplings in 4 compare well with those previously reported for parent systems. Although the coexistence of the spin-orbit coupling (SOC) of the low-spin iron(III) and lanthanide(III) ions in the remaining compounds together with the ligand field effects mask the visualization and make difficult the evaluation of the possible magnetic interactions in them, we were able to do it through a SOC model applied on exact or effective Hamiltonians. Frequency-dependent alternating current magnetic susceptibility signals in the temperature range 2.0-9.0 K under zero and non-zero static fields were observed for 5-7 which indicate slow magnetic relaxation (SMM) behavior. The usual absence of χ''_M maxima moved us to estimate their energy barriers through ln(χ''_M/ χ'_M) vs. 1/T plots, obtaining values from 25 to 40 cm^-1.

Heterobimetallic complexes from 0D clusters to 3D networks based on various polycyanometallates and [Cu(dmpn)2]2+ (dmpn = 2,2-dimethyl-1,3-diaminopropane): synthesis, crystal structures and magnetic properties

Six new cyanide-bridged complexes (0–3D) have been assembled by employing one copper compound and six cyano precursors. Investigation of the magnetic properties revealed the ferro- or antiferromagnetic coupling between Fe^III/Cr^I ion and Cu^II ion.

Heterotrimetallic complexes in molecular magnetism

The most representative examples of coordination compounds containing three different paramagnetic metal ions are reviewed, with a special emphasis on their magnetic properties.

Single-molecule magnet behavior in three cyano-bridged heterometallic Fe(III)-Ni(II) clusters

One trinuclear and two tetranuclear cyanide-bridged Fe(III)-Ni(II) complexes were synthesized via treatment of a tricyanometallate with divalent Ni salts in the presence of 1-butylimidazole, 2,2-bipyrimidyl and 1,10-phenanthroline, respectively. Magnetic property studies demonstrated that the three complexes exhibit single-molecule magnet behavior as a result of strong intracluster ferromagnetic coupling and weak intercluster magnetic interactions.

A new series of cyanide-bridged heterobimetallic FeIII–FeIII/MnIII/CuII one-dimensional complexes: synthesis, crystal structures, and magnetic properties

Four new cyanide-bridged Fe^III–Fe^III/Mn^III/Cu^II one-dimensional complexes have been assembled using K[Fe(bpdBrb)(CN)₂]·2H₂O (1) as building blocks, and structurally characterized and magnetically investigated.