The new complex [Co(III)2Dy(III)2(OMe)2(teaH)2(Piv)6] in the {Co(III)2Dy(III)2} family, shows two well resolved thermal activated magnetization relaxation pathways under AC experiments in zero DC field. Fitted crystal field parameters suggest that the origin of these two pathways relies on two different excited mJ sub-levels.

We have successfully prepared and structurally characterized a family of butterfly-like [CoLn] complexes where all magnetic properties are due to the Ln(iii) ions. The complexes with Ln = Tb(1), Dy(2), Ho(3), Er(4) and Yb(5) are iso-structural. An exception is the complex with Ln = Gd(6) which strings in a one dimensional chain. The structural similarity together with the high tendency of the crystallites to align under an applied magnetic field allowed an overall DC magnetic data treatment to extract phenomenological crystal field parameters and hence to determine the ground state multiplet energy level splitting. The Dy(iii) member is the only one showing slow relaxation of magnetization under zero DC applied field, while all the others need a small DC applied field.

In this work we review the Co 2 III Ln 2 III family of compounds reported up to date that shows SMM features. The vast majority of them show a butterfly arrangement with Ln III ions placed at the body positions. The number of Dy III examples constitutes the majority, probably because of the intrinsic properties of this lanthanide ion regarding SMMs characteristics. Butterfly complexes have a SAP geometry around Ln III ions with a variety of distortion degrees. However, when looking at the key U eff parameter trend through this family of complexes, it becomes clear that a pure geometrical consideration is not [a] he started his independent research career in the field of molecular magnetism and coordination chemistry. The main research topic of his group is the synthesis, structural characterization and magnetic properties study of molecular nanomagnets.2067 III Ln 2 III unit. As low-spin Co III is a diamagnetic ion, this type of compounds, from the magnetic point of view, are genuine dinuclear lanthanide compounds. Moreover, the inclusion of the Co III coordination spheres offers more synthetic Eur.

We have prepared and structurally characterized a new member of the butterfly-like {Co(III) 2 Dy(III) 2 } single-molecule magnets (SMMs) through further Co(III) decoration, with the formula [Co(III) 4 Dy(III) 2 (OH)2 (teaH)2 (tea)2 (Piv)6 ] (teaH3 =triethanolamine; Piv=trimethylacetate or pivalate). Direct current (DC) susceptibility and magnetization measurements were performed allowing the extraction of possible crystal-field parameters. A simple electrostatic modeling shows reasonable agreement with experimental data. Alternating current (AC) susceptibility measurements under a zero DC field and under small applied fields were performed at different frequencies (i.e., 10-1500 Hz) and at low temperatures (i.e., 2-10 K). Multiple magnetization relaxation pathways are observed. Comparison with previously reported {Co(III) 2 Dy(III) 2 } complex measurements allows an overall discussion about the origin of the dynamic behavior and its relationship with crystal-field split ground multiplet sublevels.

Keywords: Cluster compounds / Cobalt / Mixed-valent compounds / Magnetic properties / Density functional calculations / EPR spectroscopyWe have synthesised and structurally characterised a new pentanuclear mixed-valent cobalt cluster of formula [Co II 3 Co III 2 (OH) 2 (piv) 6 (L) 2 (H 2 O) 4 ] (piv = trimethylacetate, H 2 L = salicylideneanthranillic acid) from reaction of a dinuclear cobalt pivalate precursor with a Schiff base type ligand under mild reaction conditions. The core structure can be conveniently described as two fused Co 3 -μ 3 -OH triangles with a strict unique sharing vertex point. A complete picture of the magnetic behaviour of this compound is presented. Through combined use of susceptibility, magnetisation, and[a]

In memory of the beloved extraordinary chemist Vicente "Vinko" G. PovseWe are reporting the synthesis and structural characterization of a new family of butterfly complexes with formula [Co 2 III Ln 2 III À (μ 3 À (OR)) 2 ] where À OR is an alcohol-amine type ligand, in this case N-methyldiethanolamine (H 2 mdea) with Ln=Tb, Dy, Ho, Er and Yb. This new family adds to the previously reported one, where the alcohol-amine ligand is triethanolamine (H 3 tea), and allows a one-to-one comparison between them. From a combined experimental study, that included DC and AC magnetometry as well as HF-EPR measurements, and a theoretical approach based on Broken-Symmetry DFT and CASSCF-SA-SOC ab-initio computations, we discuss the single molecule magnet (SMM) performance in these complexes. We focus in a few key structural parameters that correlate with the magnetization relaxation behaviour observed along the different explored lanthanide ions.

We are reporting two new mixed valent Co(ii)/Co(iii) polynuclear complexes, {Co(II)6Co(III)3} and {Co(II)Co(III)4}, bearing different amount of Co(ii) ions in their cores, through the employment of the multidentate triethanolamine (teaH3) ligand in different stoichiometric ratios. We present a complete picture of the magnetic behaviour of both complexes through a combined usage of the susceptibility, magnetization and X-band EPR data as well as broken-symmetry DFT calculations. Compound shows an atypical spin-only behaviour, probably due to the presence of four and five coordinated Co(ii) sites as well as highly distorted six coordinated Co(ii) ions, promoting a high degree of orbital contribution quenching. Through the usage of a simplified exchange coupling scheme and relying on DFT based magneto-structural correlation we have been able to explain the observed diamagnetic ground state. Concerning compound , DC magnetic data supported by X-band EPR measurements suggest the existence of anisotropy with a zero-field splitting parameter D, at least in the range of 2-10 cm(-1). In agreement with this description, a slow relaxation of magnetization is observed after applying a small external magnetic field, under AC measurements. Field and temperature dependence of the characteristic relaxation time establishes a thermal barrier for magnetization reversal of about 25 cm(-1), which is in good agreement with the energy splitting of the |±1/2〉 and |±3/2〉 doublets established from static magnetic measurements.

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