Temperature Induced Reversible Switching of the Magnetic Anisotropy in a Neodymium Complex Adsorbed on Graphite.

Controlling the magnetic anisotropy of molecular layers assembled on a surface is one of the challenges that needs to be addressed to create the next-generation spintronic devices. Recently, metal complexes that show a reversible solid-state switch of their magnetic anisotropy in response to physical stimuli, such as temperature and magnetic field, have been discovered. The complex Nd(trensal) (H3trensal = 2,2',2''-tris(salicylideneimino)triethylamine) is predicted to exhibit such property. An ultra-thin film of Nd(trensal) is deposited on highly ordered pyrolytic graphite as a proof-of-concept system to show that this property can be retained at the nanoscale on a layered material. By combining single crystal magnetometric measurements and synchrotron X-ray-based absorption techniques, supported by multiplet ligand field simulations based on the trigonal crystal field surrounding the lanthanide centre, it is demonstrated that changing the temperature reverses the magnetic anisotropy of an ordered film of Nd(trensal), thus opening significant perspectives for the realization of a novel family of temperature-controlled molecular spintronic devices.

LnDOTA puppeteering: removing the water molecule and imposing tetragonal symmetry.

Complexes of lanthanide(iii) ions (Ln) with tetraazacyclododecane-N,N',N'',N'''-tetraacetate (DOTA) are a benchmark in the field of magnetism due to their well-investigated and sometimes surprising features. Ab initio calculations suggest that the ninth ligand, an axial water molecule, is key in defining the magnetic properties because it breaks the potential C4 symmetry of the resulting complexes. In this paper, we experimentally isolate the role of the water molecule by excluding it from the metal coordination sphere without altering the chemical structure of the ligand. Our complexes are therefore designed to be geometrically tetragonal and strict crystallographic symmetry is achieved by exploiting a combination of solution ionic strength and solid state packing effects. A thorough multitechnique approach has been used to unravel the electronic structure and magnetic anisotropy of the complexes. Moreover, the geometry enhancement allows us to predict, using only one angle obtained from the crystal structure, the ground state composition of all the studied derivatives (Ln = Tb to Yb). Therefore, these systems also provide an excellent platform to test the validity and limitations of the ab initio methods. Our combined experimental and theoretical investigation proves that the water molecule is indeed key in defining the magnetic anisotropy and the slow relaxation of these complexes.

Efficient Spin-Selective Electron Transport at Low Voltages of Thia-Bridged Triarylamine Hetero[4]helicenes Chemisorbed Monolayer.

The Chirality Induced Spin Selectivity (CISS) effect describes the capability of chiral molecules to act as spin filters discriminating flowing electrons according to their spin state. Within molecular spintronics, efforts are focused on developing chiral-molecule-based technologies to control the injection and coherence of spin-polarized currents. Herein, for this purpose, we study spin selectivity properties of a monolayer of a thioalkyl derivative of a thia-bridged triarylamine hetero[4]helicene chemisorbed on a gold surface. A stacked device assembled by embedding a monolayer of these molecules between ferromagnetic and diamagnetic electrodes exhibits asymmetric magnetoresistance with inversion of the signal according to the handedness of molecules, in line with the presence of the CISS effect. In addition, magnetically conductive atomic force microscopy reveals efficient electron spin filtering even at unusually low potentials. Our results demonstrate that thia[4]heterohelicenes represent key candidates for the development of chiral spintronic devices.

VdW Mediated Strong Magnetic Exchange Interactions in Chains of Hydrogen-Free Sublimable Molecular Qubits.

Sulfur-rich molecular complexes of dithiolene-like ligands are appealing candidates as molecular spin qubits because spin coherence properties are enhanced in hydrogen-free environments. Herein, we employ the hydrogen-free mononegative 1,3,2-dithiazole-4-thione-5-thiolate (dttt-) ligand as an alternative to common dinegative dithiolate ligands. We report the first synthesis and structural characterization of its Cu2+, Ni2+, and Pt2+ neutral complexes. The XPS analysis of thermal deposition of [Cu(dttt)2] in UHV conditions indicates that films of intact molecules can be deposited on surfaces by sublimation. Thanks to a combined approach employing DC magnetometry and DFT calculations, we highlighted AF exchange interactions of 108 cm-1 and 36 cm-1 attributed to the two different polymorph phases. These couplings are exclusively mediated by S···S VdW interactions, which are facilitated by the absence of counterions and made particularly efficient by the diffuse electron density on S atoms. Furthermore, the spin dynamics of solid-state magnetically diluted samples was investigated. The longest observed T m is 2.3 µs at 30 K, which significantly diverges from the predicted T m > 100 µs. These results point to the diluting matrix severely affecting the coherence lifetime of Cu2+ species via different factors, such as the contributions of neighboring 14N nuclei and the formation of radical impurities in a non-completely controllable way. However, the ease of processing [Cu(dttt)2] via thermal sublimation can allow dispersion in matrices better suited for coherent spin manipulation of isolated molecules and the realization of AF-coupled VdW structures on surfaces.

Quantum spin coherence and electron spin distribution channels in vanadyl-containing lantern complexes.

We herein investigate the heterobimetallic lantern complexes [PtVO(SOCR)4] as charge neutral electronic qubits based on vanadyl complexes (S = 1/2) with nuclear spin-free donor atoms. The derivatives with R = Me (1) and Ph (2) give highly resolved X-band EPR spectra in frozen CH2Cl2/toluene solution, which evidence the usual hyperfine coupling with the 51V nucleus (I = 7/2) and an additional superhyperfine interaction with the I = 1/2 nucleus of the 195Pt isotope (natural abundance ca. 34%). DFT calculations ascribe the spin density delocalization on the Pt2+ ion to a combination of π and δ pathways, with the former representing the predominant channel. Spin relaxation measurements in frozen CD2Cl2/toluene-d8 solution between 90 and 10 K yield Tm values (1-6 µs in 1 and 2-11 µs in 2) which compare favorably with those of known vanadyl-based qubits in similar matrices. Coherent spin manipulations indeed prove possible at 70 K, as shown by the observation of Rabi oscillations in nutation experiments. The results indicate that the heavy Group 10 metal ion is not detrimental to the coherence properties of the vanadyl moiety and that Pt-VO lanterns can be used as robust spin-coherent building blocks in materials science and quantum technologies.

Direct detection of spin polarization in photoinduced charge transfer through a chiral bridge.

It is well assessed that the charge transport through a chiral potential barrier can result in spin-polarized charges. The possibility of driving this process through visible photons holds tremendous potential for several aspects of quantum information science, e.g., the optical control and readout of qubits. In this context, the direct observation of this phenomenon via spin-sensitive spectroscopies is of utmost importance to establish future guidelines to control photo-driven spin selectivity in chiral structures. Here, we provide direct proof that time-resolved electron paramagnetic resonance (EPR) can be used to detect long-lived spin polarization generated by photoinduced charge transfer through a chiral bridge. We propose a system comprising CdSe quantum dots (QDs), as a donor, and C60, as an acceptor, covalently linked through a saturated oligopeptide helical bridge (χ) with a rigid structure of ∼10 Å. Time-resolved EPR spectroscopy shows that the charge transfer in our system results in a C60 radical anion, whose spin polarization maximum is observed at longer times with respect to that of the photogenerated C60 triplet state. Notably, the theoretical modelling of the EPR spectra reveals that the observed features may be compatible with chirality-induced spin selectivity, but the electronic features of the QD do not allow the unambiguous identification of the CISS effect. Nevertheless, we identify which parameters need optimization for unambiguous detection and quantification of the phenomenon. This work lays the basis for the optical generation and direct manipulation of spin polarization induced by chirality.

Mixed-Sandwich Titanium(III) Qubits on Au(111): Electron Delocalization Ruled by Molecular Packing.

Organometallic sandwich complexes are versatile molecular systems that have been recently employed for single-molecule manipulation and spin sensing experiments. Among related organometallic compounds, the mixed-sandwich S = 1/2 complex (η8-cyclooctatetraene)(η5-cyclopentadienyl)titanium, here [CpTi(cot)], has attracted interest as a spin qubit because of the long coherence time. Here the structural and chemical properties of [CpTi(cot)] on Au(111) are investigated at the monolayer level by experimental and computational methods. Scanning tunneling microscopy suggests that adsorption occurs in two molecular orientations, lying and standing, with a 3:1 ratio. XPS data evidence that a fraction of the molecules undergo partial electron transfer to gold, while our computational analysis suggests that only the standing molecules experience charge delocalization toward the surface. Such a phenomenon depends on intermolecular interactions that stabilize the molecular packing in the monolayer. This orientation-dependent molecule-surface hybridization opens exciting perspectives for selective control of the molecule-substrate spin delocalization in hybrid interfaces.

A dysprosium single molecule magnet outperforming current pseudocontact shift agents.

A common criterion for designing performant single molecule magnets and pseudocontact shift tags is a large magnetic anisotropy. In this article we present a dysprosium complex chemically designed to exhibit strong easy-axis type magnetic anisotropy that is preserved in dichloromethane solution at room temperature. Our detailed theoretical and experimental studies on the magnetic properties allowed explaining several features typical of highly performant SMMs. Moreover, the NMR characterization shows remarkably large chemical shifts, outperforming the current state-of-the art PCS tags.

Hetero-tri-spin systems: an alternative stairway to the single molecule magnet heaven?

The search for molecule-based magnetic materials has stimulated over the years the development of extremely rich coordination chemistry. Various combinations of spin carriers have been investigated and illustrated by a plethora of hetero-spin complexes: 3d-nd, 3d-4f, 2p-3d, and 2p-4f. More recently, two other classes of hetero-spin complexes have grown rapidly: compounds containing three different paramagnetic metal ions, or one radical and two different paramagnetic metal ions (all within the same molecular entity). Such new classes of systems represent a challenge both from a synthetic and theoretical point of view. Indeed, the synthetic control and the understanding of the spin topology effect on the overall magnetic behavior from first-principles is a difficult problem to be solved. The presence of different spin carriers in a single molecule makes such compounds particularly interesting because they offer the possibility of developing new magnetic properties, different from those of hetero-bi-spin or homo-spin systems. A critical overview taking the case of 2p-3d-4f complexes is the focus of this perspective paper. An original organic picture of the state-of-art in this field and new hints about the main directions that should be pursued to achieve hetero-tri-spin systems with large anisotropy barriers, low quantum tunneling of magnetization and, possibly, large blocking temperatures are provided in this article through an analysis based on numerically revisiting already published data and a critical survey of the literature reported so far. The reasons for the limited success obtained for the largely used 3d-2p-4f topology are given along with the ones explaining the failure for the 2p-4f-3d case. The still never synthesized linear 2p-3d-4f spin topology seemed to be the most promising one based on the results obtained for the unique closed hetero-tri-spin closed triangular system synthesized so far.

A Complete Ab Initio View of Orbach and Raman Spin-Lattice Relaxation in a Dysprosium Coordination Compound.

The unique electronic and magnetic properties of lanthanide molecular complexes place them at the forefront of the race toward high-temperature single-molecule magnets and magnetic quantum bits. The design of compounds of this class has so far being almost exclusively driven by static crystal field considerations, with an emphasis on increasing the magnetic anisotropy barrier. Now that this guideline has reached its maximum potential, a deeper understanding of spin-phonon relaxation mechanisms presents itself as key in order to drive synthetic chemistry beyond simple intuition. In this work, we compute relaxation times fully ab initio and unveil the nature of all spin-phonon relaxation mechanisms, namely Orbach and Raman pathways, in a prototypical Dy single-molecule magnet. Computational predictions are in agreement with the experimental determination of spin relaxation time and crystal field anisotropy, and show that Raman relaxation, dominating at low temperature, is triggered by low-energy phonons and little affected by further engineering of crystal field axiality. A comprehensive analysis of spin-phonon coupling mechanism reveals that molecular vibrations beyond the ion's first coordination shell can also assume a prominent role in spin relaxation through an electrostatic polarization effect. Therefore, this work shows the way forward in the field by delivering a novel and complete set of chemically sound design rules tackling every aspect of spin relaxation at any temperature.

Magnetic anisotropy on demand exploiting high-pressure as remote control: an ab initio proof of concept.

Lanthanide based single molecule magnets have recently become very promising systems for creating single molecule devices working at high temperatures (nitrogen boiling temperature). However, the variation of the direction of the anisotropy tensor as a function of the applied pressure still represents a quite unexplored field. Application of external pressure can be a promising method toward neat control of magnetic anisotropy and relaxation processes in the bulk phase. Required criteria for being eligible for such systems are as follows: the presence of first excited energy levels with significantly different orientations of its anisotropy tensor; sufficiently low energies of such levels so that they can mix with the ground state; and the possibility of tuning their energies by small geometrical perturbations. The archetype compound {Na[DyDOTA(H2O)]·4H2O} (1) (H4DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-N,N',N'',N'''-tetraacetic acid) fulfils all such criteria. A state-of-the-art in silico proof of concept study on the possibility of controlling the orientation of the anisotropy tensor as a function of pressure in [DyDOTA(H2O)]- by inducing different apical water molecule (AWM) orientations and/or DOTA-induced crystal field is presented.

Single-Ion Anisotropy and Intramolecular Interactions in CeIII and NdIII Dimers.

This article reports the syntheses, characterization, structural description, together with magnetic and spectroscopic properties of two isostructural molecular magnets based on the chiral ligand N,N'-bis((1,2-diphenyl-(pyridine-2-yl)methylene)-(R,R/S,S)-ethane-1,2-diamine), L1, of general formula [Ln2(RR-L1)2(Cl6)]·MeOH·1.5H2O, (Ln = Ce (1) or Nd (2)). Multifrequency electron paramagnetic resonance (EPR), cantilever torque magnetometry (CTM) measurements, and ab initio calculations allowed us to determine single-ion magnetic anisotropy and intramolecular magnetic interactions in both compounds, evidencing a more important role of the anisotropic exchange for the NdIII derivative. The comparison of experimental and theoretical data indicates that, in the case of largely rhombic lanthanide ions, ab initio calculations can fail in determining the orientation of the weakest components, while being reliable in determining their principal values. However, they remain of paramount importance to set the analysis of EPR and CTM on sound basis, thus obtaining a very precise picture of the magnetic interactions in these systems. Finally, the electronic structure of the two complexes, as obtained by this approach, is consistent with the absence of zero-field slow relaxation observed in ac susceptibility.

Magnetic Anisotropy Trends along a Full 4f-Series: The fn+7 Effect.

The combined experimental and computational study of the 13 magnetic complexes belonging to the Na[LnDOTA(H2O)] (H4DOTA = tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid and Ln = Ce-Yb) family allowed us to identify a new trend: the orientation of the magnetic anisotropy tensors of derivatives differing by seven f electrons practically coincide. We name this trend the fn+7 effect. Experiments and theory fully agree on the match between the magnetic reference frames (e.g., the easy, intermediate, and hard direction). The shape of the magnetic anisotropy of some couples of ions differing by seven f electrons might seem instead different at first look, but our analysis explains a hidden similarity. We thus pave the way toward a reliable predictivity of the magnetic anisotropy of lanthanide complexes with a consequent reduced need of computational and synthetical efforts. We also offer a way to gain information on ions with a relatively small total angular momentum (i.e., Sm3+ and Eu3+) and on the radioactive Pm3+, which are difficult to investigate experimentally.

Exploring the Organometallic Route to Molecular Spin Qubits: The [CpTi(cot)] Case.

The coherence time of the 17-electron, mixed sandwich complex [CpTi(cot)], (η8 -cyclooctatetraene)(η5 -cyclopentadienyl)titanium, reaches 34 µs at 4.5 K in a frozen deuterated toluene solution. This is a remarkable coherence time for a highly protonated molecule. The intramolecular distances between the Ti and H atoms provide a good compromise between instantaneous and spin diffusion sources of decoherence. Ab initio calculations at the molecular and crystal packing levels reveal that the characteristic low-energy ring rotations of the sandwich framework do not yield a too detrimental spin-lattice relaxation because of their small spin-phonon coupling. The volatility of [CpTi(cot)] and the accessibility of the semi-occupied, non-bonding d z 2 orbital make this neutral compound an ideal candidate for single-qubit addressing on surface and quantum sensing in combination with scanning probe microscopy.

An Oxalate-Bridged Copper(II) Complex Combining Monodentate Benzoate, 2,2'-bipyridine and Aqua Ligands: Synthesis, Crystal Structure and Investigation of Magnetic Properties.

A dinuclear copper(II) complex of formula [{Cu(bipy)(bzt)(OH2)}2(µ-ox)] (1) (where bipy = 2,2'-bipyridine, bzt = benzoate and ox = oxalate) was synthesised and characterised by diffractometric (powder and single-crystal XRD) and thermogravimetric (TG/DTG) analyses, spectroscopic techniques (IR, Raman, electron paramagnetic resonance spectroscopy (EPR) and electronic spectroscopy), magnetic measurements and density functional theory (DFT) calculations. The analysis of the crystal structure revealed that the oxalate ligand is in bis(bidentate) coordination mode between two copper(II) centres. The other four positions of the coordination environment of the copper(II) ion are occupied by one water molecule, a bidentate bipy and a monodentate bzt ligand. An inversion centre located on the ox ligand generates the other half of the dinuclear complex. Intermolecular hydrogen bonds and π-π interactions are responsible for the organisation of the molecules in the solid state. Molar magnetic susceptibility and field dependence magnetisation studies evidenced a weak intramolecular-ferromagnetic interaction (J = +2.9 cm-1) between the metal ions. The sign and magnitude of the calculated J value by density functional theory (DFT) are in agreement with the experimental data.

Quantum dynamics of a single molecule magnet on superconducting Pb(111).

Magnetic materials interfaced with superconductors may reveal new physical phenomena with potential for quantum technologies. The use of molecules as magnetic components has already shown great promise, but the diversity of properties offered by the molecular realm remains largely unexplored. Here we investigate a submonolayer of tetrairon(III) propeller-shaped single molecule magnets deposited on a superconducting lead surface. This material combination reveals a strong influence of the superconductor on the spin dynamics of the single molecule magnet. It is shown that the superconducting transition to the condensate state switches the single molecule magnet from a blocked magnetization state to a resonant quantum tunnelling regime. Our results open perspectives to control single molecule magnetism via superconductors and to use single molecule magnets as local probes of the superconducting state.

Covalency and magnetic anisotropy in lanthanide single molecule magnets: the DyDOTA archetype.

Lanthanide ions when complexed by polyamino-polycarboxylate chelators form a class of compounds of paramount importance in several research and technological areas, particularly in the fields of magnetic resonance and molecular magnetism. Indeed, the gadolinium derivative is one of the most employed contrast agents for magnetic resonance imaging while the dysprosium one belongs to a new generation of contrast agents for T2-weighted MRI. In molecular magnetism, Single Molecule Magnets (SMMs) containing lanthanide ions have become readily popular in the chemistry and physics communities since record energy barriers to the reversal of magnetization were reported. The success of lanthanide complexes lies in their large anisotropy due to the contribution of the unquenched orbital angular momentum. However, only a few efforts have been made so far to understand how the f-orbitals can be influenced by the surrounding ligands. The outcomes have been rationalized using mere electrostatic perturbation models. In the archetype compound [Na{Dy(DOTA) (H2O)}]·4H2O (Na{DyDOTA}·4H2O) an unexpected easy axis of magnetization perpendicular to the pseudo-tetragonal axis of the molecule was found. Interestingly, a dependency of the orientation of the principal magnetization axis on the simple rotation of the coordinating apical water molecule (AWM) - highly relevant for MRI contrast - around the Dy-OAWM bond was predicted by ab initio calculations, too. However, such a behaviour has been contested in a subsequent paper justifying their conclusions on pure electrostatic assumptions. In this paper, we want to shed some light on the nature of the subtle effects induced by the water molecule on the magnetic properties of the DyDOTA archetype complex. Therefore, we have critically reviewed the structural models already published in the literature along with new ones, showing how the easy axis orientation can dangerously depend on the chosen model. The different computed behaviors of the orientation of the easy axis of magnetization have been rationalized as a function of the energy gap between the ground and the first excited doublet. Magneto-structural correlations together with a mapping of the electrostatic potential generated by the ligands around the Dy(iii) ion through a multipolar expansion have also been used to evidence and quantify the covalent contribution of the AWM orbitals.

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 [MIIDyIII(LH)(hfac)5] (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. For the [CoIIDyIIIRad] derivative obtained using a nitronyl-nitroxide chiral ligand, a high energy barrier (∼200 cm-1) and a slow relaxation behavior below 30 K were found and rationalized by ab initio calculations. The improvement of magnetic properties comes from the synergy of optimal single ions properties and exchange couplings contributions where the CoII-Rad interaction becomes the leading one. The role played by this interaction is clearly proved by the investigation of the magnetic properties of the [ZnIIDyIIIRad] derivative, with a much lower energy barrier (12.7 cm-1) and by the lack of SMM behavior of the previously reported [CoIIDyIIIRad] compound ( Chem. Commun . 2017 , 53 , 6504 ), with a linear topology of spin carriers and a negligible CoII-Rad interaction.

Promoting a Significant Increase in the Photoluminescence Quantum Yield of Terbium(III) Complexes by Ligand Modification.

Two discrete mononuclear complexes, [Tb(bbpen)(NO3)] (I) and [Tb(bbppn)(NO3)] (II), for which H2bbpen = N,N'-bis(2-hydroxybenzyl)-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine and H2bbppn = N,N'-bis(2-hydroxylbenzyl)-N,N'-bis(pyridin-2-ylmethyl)-1,2-propanediamine, were synthesized and characterized by FTIR, Raman, and photoluminescence (PL, steady-state and time-resolved modes) spectroscopy. The attachment of a methyl group to the ethylenediamine portion of the ligand backbone differentiates II from I and acts as a determining feature to both the structural and optical properties of the former. The single-crystal X-ray structure of H2bbppn is described here for the first time, while that of complex II has been redetermined in the monoclinic C2 space group in light of new diffraction data. In II, selective crystallization leads to spontaneous resolution of enantiomeric molecules in different crystals. Absolute emission quantum yields (ϕ) and luminescence excited-state lifetimes (at room temperature and 11 K) were measured for both complexes. Despite their similar molecular structures, I and II exhibit remarkably different ϕ values of 21 ± 2% and 67 ± 7%, respectively, under UV excitation at room temperature. Results of quantum-mechanical (DFT and TD-DFT) calculations and experimental PL measurements also performed for H2bbpen and H2bbppn confirmed that both ligands are suitable to work as "antennas" for TbIII. Considering the 5D4 lifetime profiles and the significantly higher absolute quantum yield of II, it appears that thermally active nonradiative pathways present in I are minimized in II due to differences in the conformation of the ethylenediamine bridge.

Magnetic Cationic Copper(II) Chains and a Mononuclear Cobalt(II) Complex Containing [Ln(hfac)4]- Blocks as Counterions.

Four new heterospin compounds with molecular formula {[Cu2(hfac)3(TlTrzNIT)2][Ln(hfac)4]} n·C7H16 (LnIII = Gd (1), Tb (2), or Dy (3)) and [Co(hfac)(TlTrzNIT)2][Dy(hfac)4] (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)4]- as counterions. In compound 4, the cobalt(II) ion is coordinated to two TlTrzNIT radicals and one hfac ligand in bidentate mode leading to a mononuclear cationic complex that contains [Dy(hfac)4]- as counterion. Magnetic measurements of all complexes were performed. Magnetic data were fit considering the contributions of the copper(II)-radical chain and a paramagnetic gadolinium(III) ion for 1. The sign and magnitude of the magnetic coupling constants extracted from the fit were confirmed by density functional theory calculations. The obtained spin topology shows an alternated ferro-antiferromagnetic chain. Field-induced single molecule magnet behavior was observed for the Dy derivatives 3 and 4, in agreement with CASSCF calculations performed for the latter system.