Synthesis, Magnetic and High-Field EPR Investigation of Two Tetranuclear Ni-Based Complexes.

Two tetranuclear compounds with a cubane-like structure were synthesized from a one-pot reaction between Ni and 2,2,6,6-tetramethyl-3,5-heptanedione (Hdpm) for or 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbta) for in the presence of sodium methoxide. The crystal structures of both compounds have been determined by single-crystal X-ray diffraction, and their magnetic properties have been studied by SQUID magnetometry as well as by high-field electron paramagnetic resonance (HFEPR) spectroscopy. For , the temperature dependence of the magnetic susceptibility can be fitted by taking into account Ni···Ni ferromagnetic interactions, which leads to an = 4 ground-state spin.

SMM Behavior Tuned by an Exchange Coupling LEGO Approach for Chimeric Compounds: First 2p-3d-4f Heterotrispin Complexes with Different Metal Ions Bridged by One Aminoxyl Group.

Coordination compounds containing three different spin carriers (2p, 3d, and 4f), with the general formula [MDy(LH)(hfac)] (M = Co, Ni, Mn, Zn), have been obtained using Mannich ligands decorated with a nitronyl-nitroxide fragment. The synthetic approach is general and leads to binuclear 3d-4f complexes, the two metal ions being bridged by one aminoxyl group and by one oxygen atom arising from a hfac ligand. Triangular spin topology affords significant 2p-3d, 3d-4f, and 2p-4f exchange interactions.

Magnetic Cationic Copper(II) Chains and a Mononuclear Cobalt(II) Complex Containing [Ln(hfac)] Blocks as Counterions.

Four new heterospin compounds with molecular formula {[Cu(hfac)(TlTrzNIT)][Ln(hfac)]} ·CH (Ln = Gd (1), Tb (2), or Dy (3)) and [Co(hfac)(TlTrzNIT)][Dy(hfac)] (4), where hfac is hexafluoroacetylacetonato and TlTrzNIT is the nitronylnitroxide radical 1-( m-tolyl)-1 H-1,2,3-triazole-4-(4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were obtained. All structures were determined by single-crystal X-ray diffraction. In compounds 1-3, the TlTrzNIT radical is bridge-coordinated to copper(II) ions, leading to positively charged copper(II)-radical chains containing [Ln(hfac)] as counterions.

Synthesis, Crystal Structures, and EPR Studies of First MnLn Hetero-binuclear Complexes.

A new family of binuclear complexes [MnLn(dpm)(MeO)(MeOH)] is reported (where Ln = La (1), Pr (2), and Eu(3)). These compounds were obtained from a one-pot reaction between 2,2,6,6-tetramethyl-3,5-heptanodione (Hdpm), Mn, and the respective Ln salt in the presence of sodium methoxide. The derivative containing the diamagnetic ion La has been synthesized in order to characterize the local anisotropy of the Mn ion.

A chimeric design of heterospin 2p-3d, 2p-4f, and 2p-3d-4f complexes using a novel family of paramagnetic dissymmetric compartmental ligands.

End-off bicompartmental ligands bearing a nitronyl-nitroxide arm have been designed for synthesizing various heterospin molecular systems. These ligands can selectively interact with 3d and 4f metal ions, leading to 2p-4f, 2p-3d, and 2p-3d-4f complexes. The magnetic properties of the 2p-4f and 2p-3d-4f complexes have been investigated and rationalized by theoretical calculations.

Binuclear Lanthanide-Radical Complexes Featuring Two Centers with Different Magnetic and Luminescence Properties.

Binuclear complexes with general formula [Ln(hfac)(HO)(dppnTEMPO)] (Ln = Gd, Tb, and Dy) have been obtained using the paramagnetic ligand 1-piperidinyl-4-[(diphenylphosphinyl)amino]-2,2,6,6-tetramethyl (dppnTEMPO) as a bridge. One of the lanthanide ions is ferromagnetically coupled with the TEMPO moiety. Two of the complexes (Dy and Tb) show slow relaxation of the magnetization, and the non-magneto-equivalence of the two Ln ions was clearly observed.

First coordination compounds based on a bis(imino nitroxide) biradical and 4f metal ions: synthesis, crystal structures and magnetic properties.

The synthesis, crystal structures and magnetic properties of two families of heterospin complexes containing lanthanide ions and a bis(imino nitroxide) biradical (IPhIN = 1-iodo-3,5-bis(4',4',5',5'-tetramethyl-4',5'-dihydro-1H-imidazole-1'-oxyl)benzene) are reported: in [Ln2(hfac)6(IPhIN)(H2O)2] compounds, two lanthanide ions [Ln = Gd(III) (1) and Dy(III) (2)] are coordinated to the biradical, and in [Ln(hfac)3(IPhIN)(H2O)] compounds, one lanthanide ion (Ln = Tb(III) (3), Gd(III) (4) or Dy(III) (5)) is coordinated to the biradical. Ferromagnetic intramolecular magnetic interactions between Gd(III) and the biradical were found for 1 and 4, while intramolecular magnetic interactions between the radicals were ferro- and antiferromagnetic, respectively. Compound 2 shows a field induced slow relaxation of magnetization, which (under an external applied field of 2 kOe) exhibits an activation energy barrier of ΔE/kB = 27 K and a pre-exponential factor of 1.

New families of hetero-tri-spin 2p-3d-4f complexes: synthesis, crystal structures, and magnetic properties.

In this work we report the synthesis, crystal structures, and magnetic behavior of 2p-3d-4f heterospin systems containing the nitroxide radical 4-azido-2,2,6,6-tetramethylpiperidine-1-oxyl radical (N3tempo). These compounds were synthesized through a one-pot reaction by using [Cu(hfac)2], [Ln(hfac)3] (hfac = hexafluoroacetylacetonate, Ln = Dy(III), Tb(III) or Gd(III)), and the N3tempo radical. Depending on the stoichiometric ratio used, the synthesis leads to penta- or trimetallic compounds, with molecular formulas [Cu3Ln2(hfac)8(OH)4(N3tempo)] (Ln = Gd, Tb, Dy) and [CuLn2(hfac)8(N3tempo)2(H2O)2] (Ln = Gd, Dy).

New synthetic route toward heterometallic 3d-3d' and 3d-4f single-molecule magnets. The first Co(II)-Mn(III) heterometallic complex.

Four tetranuclear heterometallic complexes, [Co(II)2Mn2(III)(dpm)4(MeO)6] (1) and [Ln(III)2Mn(III)2(dpm)6(MeO)6(MeOH)n], where Ln = Gd (2, n = 2), Tb (3, n = 2), and Dy (4, n = 0), have been obtained following the same general synthetic route, namely, the one-pot reaction between 2,2,6,6-tetrametil-3,5-heptanodione (Hdpm), MnCl2 and CoCl2 or Ln(NO3)3 in the presence of sodium methoxide. Within the four compounds, the metal ions bridged by methoxide ligands display a defect-diheterocubane core. Compounds 1, 3, and 4 show slow relaxation of the magnetization below 4 K.

New copper(II)-radical one dimensional chain: Synthesis, crystal structure, EPR, magnetic properties and DFT calculations.

The novel chain compound [Cu(Phtfac)(2)(NITpPy)](n) (where NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and Phtfac = 4,4,4-trifluoro-1-phenylbutane-1,3-dione) was synthesized and characterized structurally, magnetically and by EPR. The compound contains two non equivalent Cu(II) ions, Cu1 and Cu2, located at inversion centers and bridged by a NITpPy ligand coordinating Cu1 through the pyridine donor atom, and Cu2 through a N-O group, resulting in a head-to-head chain structure. The chain exhibits an unusual spin topology with two alternating pairs of magnetic coupling constants.