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Magnetic semiconductors, with integrated properties of ferromagnets and semiconductors, are significant for developing next‐generation spintronic devices. Herein two atomically precise clusters of dysprosium(III) tellurides, formulated respectively as [Na2(15‐crown‐5)3(py)2][(η5‐Cp*Dy)5(Te)6](py)4 (Dy5Te6, Cp*=pentamethylcyclopentadienyl; py=pyridine) and [K(2,2,2‐cryptand)]2[(η5‐Cp*Dy)6(Te3)(Te2)2(Te)3] (Dy6Te10), are reported. Crystallographic studies revealed the presence of multifarious tellurido ligands within the polyhedral cluster cores. Spectroscopic and magnetic studies showed that both clusters are single‐molecule magnets exhibiting slow magnetic relaxation behaviors at low temperatures and semiconductors with low optical band gaps comparable to benchmark semiconductors. These clusters represent probably the first lanthanide‐based molecular magnetic semiconductors. [ABSTRACT FROM AUTHOR]

Compared with aggregate spin behavior, single‐molecule spin behavior can be accurately understood, controlled, and applied at the level of basic building blocks. The potential of single‐molecule electronic and nuclear spins for monitoring and control represents a beacon of promise for the advancement of molecular spin devices, which are fabricated by connecting a single molecule between two electrodes. Metal complexes, celebrated for their superior magnetic attributes, are widely used in the devices to explore spin effects. Moreover, single‐molecule electrical techniques with high signal‐to‐noise ratio, temporal resolution, and reliability help to understand the spin characteristics. In this review, the focus is on the devices with metal complexes, especially single‐molecule magnets, and systematically present experimental and theoretical state of the art of this field at the single‐molecule level, including the fundamental concepts of the electronic and nuclear spin and their basic spin effects. Then, several experimental methods developed to regulate the spin characteristics of metal complexes at single‐molecule level are introduced, as well as the corresponding intrinsic mechanisms. A brief discussion is provided on the comprehensive applications and the considerable challenges of single‐molecule spin devices in detail, along with a prospect on the potential future directions of this field. [ABSTRACT FROM AUTHOR]

The introduction of the cerium(III) analogue (1‐Ce, Ln = Ce) of (tert‐butoxido)chloridopentakis(tetrahydrofuran)lanthanide(III) tetraphenylborate tetrahydrofuran disolvate, [Ln{OC(CH3)3}Cl(C4H8O)5][B(C6H5)4]·2C4H8O or [Ln(OtBu)Cl(THF)5](BPh4)·2THF (1‐Ln) has been achieved with a structural comparison between the existing solid‐state structures of other rare earth analogues and the title compound at 100 and 180 K. The cation in 1‐Ce is targeted as the cerium(III) ion possesses the criteria to exhibit slow magnetic relaxation in axial point‐charge crystal fields, akin to the dysprosium(III) ion in 1‐Dy. AC magnetic susceptibility experiments reveal no such behaviour for 1‐Ce, putting the viability of cerium‐based SMMs into question. [ABSTRACT FROM AUTHOR]

The search for new metal‐organic compounds as candidates for quantum information processing technologies is in the spotlight. Several metal ions and organic linkers have been used to obtain such compounds. Herein, we describe the synthesis, crystal structures, and cryomagnetic properties of two air‐stable isostructural neodymium(III) and europium(III) one‐dimensional (1D) coordination polymers of formula [Nd(Hmpa)3(DMSO)2]n (1) and [Eu(Hmpa)3(DMSO)2]n (2) [Hmpa=N‐(4‐methylphenyl)oxamate, and DMSO=dimethylsulfoxide]. These complexes were prepared by reacting n‐Bu4N(Hmpa) proligand [n‐Bu4N+=tetra‐n‐butylammonium] and the correspondent LnCl3 ⋅ 6H2O salt (Ln=Nd or Eu) in the open air and mild conditions. The crystal structures of 1 and 2 reveal the Ln3+ ion surrounded by two DMSO molecules and three oxamate ligands, one of them connecting to adjacent mononuclear entities through carboxylate bridges featuring a homometallic chain, while the other two establishing double N−H ⋅ ⋅ ⋅ O hydrogen bonds among adjacent polymers to give a resultant supramolecular 2D network. Cryomagnetic measurements in the static (dc) and dynamic current (ac) regimes reveal that 1 behaves as a field‐induced single‐molecule magnet below 8.8 K. A photoluminescence study shows that Hmpa ligands efficiently sensitize the luminescence of Eu3+ complex in the visible region in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

A well‐judged combination of a high axial ligand field and a bridging radical ligand in a dinuclear lanthanide complex provides a single‐molecule magnet with a higher effective energy barrier for magnetic relaxation and blocking temperature compared to its non‐radical analog due to significant magnetic exchange coupling between radical and Ln(III) ions. In this work, we report two chloranilate (CA) bridged dinuclear dysprosium complexes, [{(bbpen)Dy(μ2‐CA)Dy(bbpen)}] (1Dy) and [{(bbpen)Dy(μ2‐CA⋅)Dy(bbpen)}−{CoCp2}+] (2Dy), where 2Dy is the radical bridged Dy‐complex obtained via the chemical reduction of bridging CA moiety (H2bbpen=N,N′‐bis(2‐hydroxybenzyl)‐N,N′‐bis(2‐methylpyridyl)ethylenediamine). The presence of high electronegative phenoxide moiety enhances the axial anisotropy of pseudo‐square antiprismatic Dy(III) ions. The diffused spin of radical is efficiently coupled with anisotropic Dy(III) centres and decreases the quantum tunnelling of magnetization (QTM) in the magnetic relaxation process. The magnetic relaxation of 1Dy follows Orbach, Raman, and QTM processes whereas for 2Dy it follows Orbach and Raman Processes. Due to less involvement of the QTM relaxation process, 2Dy shows a higher thermal energy barrier (Ueff=700 K) and a high blocking temperature (6.7 K), compared to its non‐radical analog. Remarkably, the radical coupled 2Dy complex shows the highest energy barrier among the radical bridged Dy(III)‐based SMMs to date. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Many sandwich‐type lanthanide complexes show extremely high energy barriers (Ueff) for the reversal of magnetization and high blocking temperatures, being the star molecules in the research area of single‐molecule magnets. Herein, the preparation, structural determination, and magnetic property studies of two ansa‐bridged Er‐COT (COT = cyclooctatetraenyl dianion) complexes [KDME2][Er((η8‐COT‐SiMe2)2O)] (1) and [KDME2][Er((η8‐COT‐SiiPr2)2O)]K[Er((η8‐COT‐SiiPr2)2O)] (2) were reported. The Er(III) ions in both complexes are sandwiched by two COT rings which are ansa‐bridged by a [Si‐O‐Si] group. Magnetic studies reveal both complexes display slow magnetic relaxations with comparable energy barriers (228(5) K for 1, and 196(4) K for 2) and blocking temperatures (10.5 K for both complexes). The difference in the relaxation times (τ) for the two complexes was studied in details: different molecular vibrations induced by the substituents are the main reason for τ for 1 being about 10 times longer than for 2 at the same temperature above 10 K, while the quantum tunnelling of magnetization relaxation time (τQTM) for 2 is about 10 times longer than for 1 below 8 K, probably owing to the different dipolar interactions. Further rearrangement of molecular network with such ansa‐bridged SMMs is promising to design molecular magnetic materials with enhanced properties or new properties. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Many sandwich‐type lanthanide complexes show extremely high energy barriers (Ueff) for the reversal of magnetization and high blocking temperatures, being the star molecules in the research area of single‐molecule magnets. Herein, the preparation, structural determination, and magnetic property studies of two ansa‐bridged Er‐COT (COT = cyclooctatetraenyl dianion) complexes [KDME2][Er((η8‐COT‐SiMe2)2O)] (1) and [KDME2][Er((η8‐COT‐SiiPr2)2O)]K[Er((η8‐COT‐SiiPr2)2O)] (2) were reported. The Er(III) ions in both complexes are sandwiched by two COT rings which are ansa‐bridged by a [Si‐O‐Si] group. Magnetic studies reveal both complexes display slow magnetic relaxations with comparable energy barriers (228(5) K for 1, and 196(4) K for 2) and blocking temperatures (10.5 K for both complexes). The difference in the relaxation times (τ) for the two complexes was studied in details: different molecular vibrations induced by the substituents are the main reason for τ for 1 being about 10 times longer than for 2 at the same temperature above 10 K, while the quantum tunnelling of magnetization relaxation time (τQTM) for 2 is about 10 times longer than for 1 below 8 K, probably owing to the different dipolar interactions. Further rearrangement of molecular network with such ansa‐bridged SMMs is promising to design molecular magnetic materials with enhanced properties or new properties. [ABSTRACT FROM AUTHOR]

Integrating controllable spin states into single‐molecule magnets (SMMs) enables precise manipulation of magnetic interactions at a molecular level, but remains a synthetic challenge. Herein, we developed a 3d–4f metallacrown (MC) magnet [DyNi5(quinha)5(Clsal)2(py)8](ClO4) ⋅ 4H2O (H2quinha=quinaldichydroxamic acid, HClsal=5‐chlorosalicylaldehyde) wherein a square planar NiII is stabilized by chemical stacking. Thioacetal modification was employed via post‐synthetic ligand substitutions and yielded [DyNi5(quinha)5(Clsaldt)2(py)8](ClO4) ⋅ 3H2O (HClsaldt=4‐chloro‐2‐(1,3‐dithiolan‐2‐yl)phenol). Thanks to the additional ligations of thioacetal onto the NiII site, coordination‐induced spin state switching (CISSS) took place with spin state altering from low‐spin S=0 to high‐spin S=1. The synergy of CISSS effect and magnetic interactions results in distinct energy splitting and magnetic dynamics. Magnetic studies indicate prominent enhancement of reversal barrier from 57 cm−1 to 423 cm−1, along with hysteresis opening and an over 200‐fold increment in coercive field at 2 K. Ab initio calculations provide deeper insights into the exchange models and rationalize the relaxation/tunnelling pathways. These results demonstrate here provide a fire‐new perspective in modulating the magnetization relaxation via the incorporation of controllable spin states and magnetic interactions facilitated by the CISSS approach. [ABSTRACT FROM AUTHOR]

Two enantiomeric pairs of new 3d–4f heterometallic clusters have been synthesized from two enantiomer Schiff base derivatives: (R/S)-2-[(2-hydroxy-1-phenylethylimino)methyl] phenol (R-/S-H2L). The formulae of the series clusters are Co3Ln(R-L)6 (Ln = Dy (1R), Gd (2R)), Co3Ln (S-L)6 (Ln = Dy (1S), Gd (2S)), whose crystal structures and magnetic properties have been characterized. Structural analysis indicated that the above clusters crystallize in the chiral P213 group space. The central lanthanide ion has a coordination geometry of D3 surrounded by three [CoIII(L)2]– anions using six aliphatic oxygen atoms of L2− featuring a star-shaped [CoIII3LnIII] configuration. Magnetic measurements showed the presence of slow magnetic relaxation with an effective energy barrier of 22.33 K in the DyIII derivatives under a zero-dc field. Furthermore, the circular dichroism (CD) spectra of 1R and 1S confirmed their enantiomeric nature. [ABSTRACT FROM AUTHOR]

The quantum nature of single-ion magnets, single-molecule magnets, and single-chain magnets has been manifested among other phenomena by magnetic hysteresis due to slow spin relaxation, competing with fast quantum tunneling at low temperatures. Slow spin relaxation, described by Arrhenius-type law with the effective barrier energies Ueff = 50 cm–1, was discovered 3 decades ago in paramagnetic Mn12-acetate complex of oxy-bridged mixed-valence manganese ions, below the blocking temperature TB = 3 K. In contrast to common magnetic materials , it is governed primarily by magnetic anisotropy, set by zero-splitting of spin states of a magnetic ion in a field of ligands, and spin-lattice coupling. The emerging studies on the border of coordination chemistry, physics of spin systems with reduced dimensionality, and nanotechnologies, were performed in search of routes for enhancement of Ueff and TB characteristics, in line with increase of operation temperature and quantum correlation time, mandatory for quantum applications. The best results with TB ∼ 80 K and Ueff ∼ 1261 cm–1, were obtained for DyIII single-ion magnet, so far. Numerous excellent research and review articles address particular activities behind this achievement. It follows, that present challenges are dictated by the rational development of novel, smart magnetic molecules, featured by butterfly cores, cyano-bridges, 2D metal-organic frameworks, and metal-free graphene nanoclusters, as well as stable free radicals, magnetized by spare electrons. These species are briefly considered here with respect to the unique experience of international collaborative activity, established by Prof. Juan Bartolomé. [ABSTRACT FROM AUTHOR]

Lanthanide Single‐Molecule Magnets are fascinating objects that break magnetic performance records with observable magnetic bistability at the boiling temperature of liquid nitrogen, paving the way for potential applications in high‐density data storage. The switching of lanthanide SMM has been successfully achieved using several external stimuli such as redox reaction, pH titration, light irradiation or solvation/desolvation thanks to the high sensitivity of the magnetic anisotropy to any structural change in the lanthanide surrounding. Nevertheless, the use of applied high pressure as an external stimulus is largely underused, especially considering that it can be combined with high pressure X‐ray diffraction to establish a complementary structure‐property relationship. This Concept article summarizes the few relevant examples of investigations of lanthanide SMMs under applied high pressure, provides conclusions on the effect of such stimulus on molecular structures and magnetic anisotropy, and finally draws perspective on the future development of magnetic measurements under applied pressure. [ABSTRACT FROM AUTHOR]

Two five‐coordinate mononuclear DyIII single‐molecule magnets [(TrapenTMS)Dy(L)] (Trapen=tris(2‐aminobenzyl) amine; TMS=SiMe3; L=OPMe31, OPEt32) have been synthesized by the reaction of [(TrapenTMS)Dy(THF)] and OPMe3, OPEt3, respectively. The molecular structures of 1 and 2 were fully established by single crystal X‐ray diffraction. The centre DyIII ions of both complexes exhibit distorted triangular bipyramid geometries, varying with different neutral ligands L on the apex. The TrapenTMS ligand forms the pyramid base of the trigonal bipyramid. Subtle structural modifications of the axial O‐ligand terminal substituent result in different dynamic magnetic behaviors. Magnetic data analysis reveals that 1 and 2 exhibit the characteristic behavior of SMM without a dc field, accompanying an unambiguous quantum tunneling of the magnetization. Field‐induced slow magnetic relaxation was observed for 1 and 2 under an applied bias dc field of 1000 Oe, the relaxation energy barriers are 107 K and 88 K for 1 and 2, respectively. We have investigated the differences in magnetism and magnetic anisotropy between the two complexes by ab initio calculations. [ABSTRACT FROM AUTHOR]

Three mixed valence dinuclear Co (III)–Co (II)‐based complexes having general formulae of [CoIICoIII (HL2)2(L1)] [L1H = 2‐hydroxy‐1‐naphthaldehyde (1), o‐vanillin (2), and salicylaldehyde (3)] have been synthesized successfully using Schiff base (LH4) ligand. The complexes were characterized by single‐crystal XRD, powder XRD, IR, and UV–Vis analyses. The CoII ion with elongated octahedral geometry conferred significant magnetic anisotropy with D values being 64.0(8), 71.1(7), and 52.1(3) cm−1 for 1, 2, and 3, respectively. These complexes exhibited single‐molecule magnet behavior with magnetic relaxation occurring mainly through Raman for 1 and 3 whereas direct and Raman for complex 2. The analysis of the static and dynamic magnetic properties was further supported by theoretical calculations using CASSCF/DLPNO‐NEVPT2. [ABSTRACT FROM AUTHOR]

A new TEMPO derivative was synthesized and two Dy-radical complexes, [Dy(hfac)3(H2O)hmb-TEMPO] (1) and [Dy(hfac)3(hmb-TEMPO)2] (2, hmb-TEMPO = 4-((2-hydroxy-3-methoxybenzylidene)amino)-2,2,6,6-tetramethyl; hfac = hexafluoroacetylacetonate), were synthesized through reacting hmb-TEMPO radical and Dy(hfac)3 with 1:1 and 1:2 ratio, respectively. The structures of 1 and 2 were elucidated by single-crystal X-ray structural analysis. Both 1 and 2 feature mononuclear structures. Nonzero out-of-phase signals were observed for both Dy derivatives, indicating single-molecule magnet behavior. The room-temperature photoluminescence spectra of 1 and 2 exhibit strong emissions in the visible region. [ABSTRACT FROM AUTHOR]

Two enantiomeric pairs of new 3d–4f heterometallic clusters have been synthesized from two enantiomer Schiff base derivatives: (R/S)-2-[(2-hydroxy-1-phenylethylimino)methyl] phenol (R-/S-H2L). The formulae of the series clusters are Co3Ln(R-L)6 (Ln = Dy (1R), Gd (2R)), Co3Ln (S-L)6 (Ln = Dy (1S), Gd (2S)), whose crystal structures and magnetic properties have been characterized. Structural analysis indicated that the above clusters crystallize in the chiral P213 group space. The central lanthanide ion has a coordination geometry of D3 surrounded by three [CoIII(L)2]– anions using six aliphatic oxygen atoms of L2− featuring a star-shaped [CoIII3LnIII] configuration. Magnetic measurements showed the presence of slow magnetic relaxation with an effective energy barrier of 22.33 K in the DyIII derivatives under a zero-dc field. Furthermore, the circular dichroism (CD) spectra of 1R and 1S confirmed their enantiomeric nature.

The hexacoordinate Co(II) complex [Co(neo)2(cin)][BPh4]·½Me2CO (1·½Me2CO) containing trans-cinnamic acid (Hcin) and neocuproine (neo) was prepared. The compound 1·½Me2CO was characterized via single-crystal X-ray analysis, FT-IR spectroscopy, and magnetic measurements. The coordination polyhedron of the complex cation adopts a deformed octahedron shape, and cinnamate exhibits a bidentate mode of coordination, which is unusual for mononuclear Co(II) cinnamate complexes. The analysis of DC magnetic measurements with zero-field splitting (ZFS) spin Hamiltonian revealed large magnetic anisotropy defined by the axial ZFS parameter D = +53.2 cm−1. AC susceptibility measurements revealed the slow relaxation of magnetization under the applied field; thus, 1·½Me2CO behaves as a field-induced single-molecule magnet. The analysis of magnetic properties was also supported by CASSCF/NEVPT2 calculations. [ABSTRACT FROM AUTHOR]

The reaction between the ((E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide) (H2opch) ligand and the metallo-precursor [Dy(hfac)3]·2H2O led to the formation of an homometallic coordination complex with the formula [Dy2(hfac)3(H2O)(Hopch)2][Dy(hfac)4] (1). In presence of both [Dy(hfac)3] 2H2O and the Fe(II) salt, the heterobimetallic tetranuclear [FeDy3(hfac)8(H2O)2(opch)2] (2) was isolated, while the addition of the co-ligand 1,2-Bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H2bmh) led to the formation of two heterobimetallic tetranuclear complexes with the formula [Fe3Dy(hfac)6(opch)2(H2bmh)] C6H14 (3) C6H14 and [Fe2Dy2(hfac)7(opch)2(H2bmh)] 0.5C7H16 (4) 0.5C7H16. Single crystal X-ray diffraction and dc magnetic investigation demonstrated that 3 and 4 involved the iron center in the +II and +III oxidation states. Dynamic magnetic measurements highlighted the single-molecule magnet behavior of 1 and 2 in a zero applied dc field primarily due to the ferromagnetic interactions taking place in these compounds. [ABSTRACT FROM AUTHOR]

Cyano‐bridged 4d–4f molecular nanomagnets have re‐called increasing research interests in molecular magnetism since they offer more possibilities in achieving novel nanomagnets with versatile structures and magnetic interactions. In this work, four β‐diketone ligands bearing different substitution N‐sites were designed and synthesized, namely 1‐(2‐pyridyl)‐3‐(3‐pyridyl)‐1,3‐propanedione (HL1), 1,3‐Bis (3‐pyridyl)‐1,3‐propanedione (HL2), 1‐(4‐pyridyl)‐3‐(3‐pyridyl)‐1,3‐propanedione (HL3), and 1,3‐Bis (4‐pyridyl)‐1,3‐propanedione (HL4), to tune the magnetic relaxation behaviors of cyano‐bridged {DyIIIMoV} systems. By reacting with DyCl3 ⋅ 6H2O and K4Mo(CN)8 ⋅ 2H2O, four cyano‐bridged complexes, namely {[Dy[MoV(CN)8](HL1)2(H2O)3]} ⋅ 6H2O (1), {[Dy[MoV(CN)8](HL2)(H2O)3(CH3OH)]}2 ⋅ 2CH3OH ⋅ 3H2O (2), {[Dy[MoV(CN)8](HL3)(H2O)2(CH3OH)] ⋅ H2O}n (3), and {[Dy[MoV(CN)8](HL4)2(H2O)3]} ⋅ 2H2O⋅CH3OH (4) were obtained. Structural analyses revealed that 1 and 4 are binuclear complexes, 2 has a tetragonal structure, and 3 exhibits a stair‐like polymer chain structure. The DyIII ions in all complexes have eight‐coordinated configurations with the coordination spheres DyO7N1 for 1 and 4, DyO6N2 for 2, and DyO5N3 for 3. Magnetic measurements indicate that 1 is a zero‐field single‐molecule magnet (SMM) and complexes 2–4 are field‐induced SMMs, with complex 4 featuring a two‐step relaxation process. The magnetic characterizations and ab initio calculations revealed that changing the N‐sites in the β‐diketone ligands can effectively alter the structures and magnetic properties of cyano‐bridged 4d–4f nanomagnets by adjusting the coordination environments of the DyIII centers. [ABSTRACT FROM AUTHOR]

The extreme sensitivity of trivalent lanthanide ions to crystal field variations led to the emergence of single‐molecule magnetic switching under various stimuli. The use of pressure as an external stimulus instead of classic light irradiation, oxidation or any chemical reactions allows a fine tuning of the magnetic modulation. Here the well‐known pure isotopically enriched [162Dy(tta)3(L)]⋅C6H14 (162Dy) Single‐Molecule Magnet (SMM) (tta−=2‐2‐thenoyltrifluoroacetonate and L=4,5‐bis(propylthio)‐tetrathiafulvalene‐2‐(2‐pyridyl)benzimidazole‐methyl‐2‐pyridine) was experimentally investigated by single‐crystal diffraction and squid magnetometry under high applied pressures. Both reversible piezochromic properties and pressure modulation of the slow magnetic relaxation behavior were demonstrated and supported by ab initio calculations. The magnetic study of the diluted sample [162Dy0.05Y0.95(tta)3(L)]⋅C6H14 (162Dy@Y) indicated that variations in the electronic structure have mainly intermolecular origin with weak intramolecular contribution. Quantitative magnetic interpretation concludes to a deterioration of the Orbach process for the benefit of both Raman and QTM mechanisms under applied pressure. [ABSTRACT FROM AUTHOR]

Two dichloride-bridged dinuclear dysprosium(III) complexes based on salen ligands, namely, [Dy(L¹)(μ-Cl)(thf)]2 (1; H2L¹=N,N'-bis(3,5-di-tert-butylsalicylidene)phenylene-diamine) and [Dy2(L²)2(μ-Cl)2(thf)2]2 (2; H2L²=N,N'-bis(3,5-ditert- butylsalicylidene)ethylenediamine) are reported. These two complexes have two short Dy--O(PhO) bonds that exhibit angles of ~90° for 1 and ~143° for 2, leading to clear slow relaxation of the magnetization for 2 and not for 1. Compound 2 has a near-identical core to the recently reported compound [Dy2(L³)2(μ-Cl)2(thf)2] (3; H2L³=N-(2-pyridylmethyl)-N,N-bis(2'-hydroxy-3',5'-di-tertbutylbenzyl) amine). The only substantial difference is the relative angle of the two O(PhO)--Dy--O(PhO) vectors, which is collinear in 2 owing to inversion symmetry and ~68° in 3 due to a molecular C2 axis. It is shown that this subtle structural difference leads to large differences in the dipolar ground states, giving rise to open magnetic hysteresis for 3 and not for 2. [ABSTRACT FROM AUTHOR]

Highly anisotropic single-molecule magnets (SMMs) have attracted much interest in the field of molecular magnetism because of their spin features and potential technological applications. Additionally, a great effort has been devoted to the functionalization of such molecule-based systems which are made with ligands containing functional groups suitable to connect SMMs to junction devices or to perform their grafting on surfaces of different substrates. We have synthesized and characterized two lipoic acid-functionalized and oxime-based Mn(III) compounds, of formula [Mn6(μ3-O)2(H2N-sao)6(lip)2(MeOH)6][Mn6(μ3-O)2(H2N-sao)6(cnph)2(MeOH)6]}·10MeOH (1) and [Mn6(μ3-O)2(H2N-sao)6(lip)2(EtOH)6]·EtOH·2H2O (2) [H2N-saoH2 = salicylamidoxime, lip = lipoate anion, cnph = 2-cyanophenolate anion]. Compound 1 crystallizes in the space group Pī of the triclinic system and 2 crystallizes in the space group C2/c of the monoclinic system. In the crystal, neighboring Mn6 entities are linked using non-coordinating solvent molecules, which are H-bonded to N atoms of –NH2 groups of amidoxime ligand. In addition, Hirshfeld surfaces of 1 and 2 were calculated to study the variety of intermolecular interactions and the different levels of importance that take place in their crystal lattice; this type of computed study is the first time performed on Mn6 complexes. The study of the magnetic properties of 1 and 2 through dc magnetic susceptibility measurements reveals the coexistence of ferromagnetic and antiferromagnetic exchange couplings between the Mn(III) metal ions in both compounds, the latter being the predominant magnetic interaction. A spin S = 4 value of the ground state was obtained using isotropic simulations of the experimental magnetic susceptibility data for both 1 and 2. Ac magnetic susceptibility measurements show features typical of slow relaxation of the magnetization in 1 and 2, which indicate that SMM behavior takes place in both compounds. [ABSTRACT FROM AUTHOR]

Photo‐responsive lanthanide‐based single‐molecule magnets (SMM) hold great promise for future switching and memory devices. Herein, we report a dysprosium phosphonate [DyIII(SCN)2(NO3)(depma)2(4‐hpy)2] (1Dy), which features a supramolecular framework containing layers of hydrogen‐bonding network and pillars of π–π interacted anthracene units. The photocycloaddition reaction of anthracene pairs led to a rapid and reversible single‐crystal‐to‐single‐crystal (SC–SC) structural transition to form the 1D coordination polymer [DyIII(SCN)2(NO3)(depma2)(4‐hpy)2]n (2Dy), accompanied by photoswitchable SMM properties with the reduction of effective energy barrier by half and the narrowing of the butterfly‐like hysteresis loop. The diluted sample showed a photo‐induced switch of the blocking temperature (TB) from 3.8 K for 1Dy@Y to 2.6 K for 2Dy@Y. This work may inspire the construction of lanthanide‐based molecular materials with targeted photo‐responsive magnetic properties. [ABSTRACT FROM AUTHOR]

Di‐nuclear citrate complexes, [CH6N3]2[M2(citH)2(H2O)4] ⋅ 2H2O (citH4=citric acid; M=FeII (Fe‐2), CoII (Co‐2), and NiII (Ni‐2)), are synthesized. The ligand, citH3−, is deprotonated only at the three carboxy groups, which is different from the previously reported tetra‐nuclear structures with cit4− ligands. Magnetic measurements reveal that these complexes have intramolecular ferromagnetism with J=∼0 cm−1 (Ni‐2), 0.02 cm−1 (Co‐2), and 0.04 cm−1 (Fe‐2). Co‐2 and Fe‐2 show slow magnetic relaxation, and are field‐induced SMMs with activation energy of spin‐reversal Ueff=27 cm−1 (Co‐2) and 4.2 cm−1 (Fe‐2). Density functional theory calculations indicate that the uniaxial anisotropy along the z‐axis of each metal ion center forms the pseudo‐serial arrangement, leading to intramolecular ferromagnetism via the magnetic dipole interaction. This work demonstrates the creation of ferromagnetic SMMs by the magnetic dipole engineering of 3d di‐nuclear metal ion centers. [ABSTRACT FROM AUTHOR]

The interest for chiral tris(β‐diketonato)lanthanide complexes in coordination chemistry is huge due to its Lewis acid character, optical activity, and the control of the final compound architecture. The reaction of equimolar quantities of [Dy((−)/(+)hfc)3(H2O)] (hfc− = 3‐(heptafluoropropylhydroxymethylene)‐(+/−)‐camphorate) and L led to the formation of a pair of enantiomers for dinuclear complexes [Dy((−)/(+)hfc)3(L)]2⋅C7H16([(−)/(+)1]⋅C7H16) (L = 4′‐(4′′′‐pyridyl‐N‐oxide)‐1,2′:6′1′′‐bis‐(pyrazolyl)pyridine]). Starting from the previous experimental protocol with the addition of bulky BArF anions, a partial dissociation of the chiral [Dy((−)/(+)hfc)3(H2O)] was observed leading to the isolation of a mono‐dimensional cationic chiral polymer {[Dy((−)/(+)hfc)2(L)][BarF]}n⋅nCH3NO2([(−)/(+)2]n⋅nCH3NO2). Natural circular dichroism (NCD) highlighted an exciton CD couplet for [(−)/(+)2]n but not for (−)/(+)1. The latter behaves as a single‐molecule magnet (SMM) with a blocking temperature up to 4 K, whereas [(−)/(+)2]n is a 1D assembly of field‐induced SMMs with a magnetic relaxation occurring through a Raman process only. [ABSTRACT FROM AUTHOR]

Binuclear heteroleptic triple-decker terbium(III) phthalocyaninate (Pc)Tb[(15C5)4Pc]Tb(Pc), where Pc2− is phthalocyaninate dianion and 15C5 is a 15-crown-5 moiety, has been synthesized as a solvent-free powder (1) and a well-defined crystal solvate with o-dichlorobenzene (Pc)Tb[(15C5)4Pc]Tb(Pc)⋅6C6H4Cl2 (2). In the crystal structure of 2, the Tb-N(Pc) distances to the nitrogen atoms in the outer and inner decks are 2.350–2.367(4) and 2.583–2.598(4) Å, respectively, and the Tb–Tb distance is 3.4667(3) Å. The twist angle between the outer and the inner decks is 42.6°. The magnetic properties were studied for both 1 and 2. The χMT magnitude of 23.3 emu⋅K/mol at 300 K indicates a contribution of two TbIII centers with the 7F6 ground state. The χMT product increases with decreasing temperature to reach 38.5 emu⋅K/mol at 2 K. This is indicative of ferromagnetic coupling between TbIII spins in accordance with previous data for triple-decker lanthanide phthalocyaninates of a dipolar nature. Both forms show a single-molecule magnet (SMM) behavior manifesting the in-phase (χ′) and out-of-phase (χ″) AC susceptibility signals in an oscillating field of 3 Oe with estimated effective spin-reversal energy barriers (Ueff) of 222(9) and 93(7) cm−1 for 1 and 2, respectively. The compounds show narrow hysteresis loops in the −1 – +1 kOe range, and the splitting between the zero-field-cooling and field-cooling curves is observed below 6 K. Thus, in spite of similar static magnetic characteristics, each form of the Tb(III) complex shows a different dynamic SMM behavior. [ABSTRACT FROM AUTHOR]

The combination of physical properties sensitive to molecular chirality in a single system allows the observation of fascinating phenomena such as magneto‐chiral dichroism (MChD) and circularly polarized luminescence (CPL) having potential applications for optical data readout and display technology. Homochiral monodimensional coordination polymers of YbIII were designed from a 2,15‐bis‐ethynyl‐hexahelicenic scaffold decorated with two terminal 4‐pyridyl units. Thanks to the coordination of the chiral organic chromophore to Yb(hfac)3 units (hfac−=1,1,1,5,5,5‐hexafluoroacetylaconate), efficient NIR‐CPL activity is observed. Moreover, the specific crystal field around the YbIII induces a strong magnetic anisotropy which leads to a single‐molecule magnet (SMM) behaviour and a remarkable room temperature MChD. The MChD‐structural correlation is supported by computational investigations. [ABSTRACT FROM AUTHOR]

Two pairs of chiral end‐on azido‐bridged dinuclear hexaazamacrocycles, [Dy2(LN6R/S)2(N3)2Cl2](BPh4)2 (1R/1S) and [Dy2(LN6R/S)2(N3)4]Cl2 (2R/2S) (LN6R/S is hexaazamacrocyclic neutral Schiff base ligand derived from 2,6‐diformylpyridine and (1R, 2R)/(1S, 2S)‐diaminocyclohexane), were constructed by adjusting the molar ratio of sodium azide to Dy(III) macrocycle precursor. Structural analyses reveal that all Dy(III) centers in complexes 1R/1S and 2R/2S are nine‐coordinate with hula‐loop coordination geometry, and the differences between 1R/1S and 2R/2S are the terminal coordination anion and counter anion. Magnetic studies indicate that complex 2S displays typical SMM behaviors under a zero dc field, whereas 1S just shows slow relaxation of magnetization resulting from a relatively weak axial crystal field. Significantly, complex 2R/2S represents the first homochiral all‐nitrogen‐coordinated lanthanide single‐molecule magnet. [ABSTRACT FROM AUTHOR]

Two tetranuclear Ni(II) complexes: [Ni4(HL1)4] ⋅ H2O (1) and [Ni4(HL2)4] ⋅ 1.5 dmf (2) where dmf=dimethylformamide, H3L1=4‐(tert‐butyl)‐2‐(((2‐hydroxy‐5‐nitrophenyl)imino)methyl)‐6‐(hydroxymethyl)phenol and H3L2=4‐(tert‐butyl)‐2‐(hydroxymethyl)‐6‐(((2‐hydroxyphenyl)‐imino)methyl)phenol, have been prepared and characterized by single crystal X‐Ray diffraction, elemental analysis and FT‐IR spectroscopy. The solid‐state structures reveal the formation of highly symmetric and asymmetric [Ni4O4] cubane cores in complexes 1 and 2, respectively. Extensive magnetic studies show that both complexes present ferromagnetic exchange interactions between the Ni(II) ions within the cubane core with g=2.113(3), J1=−7.89(8) cm−1, J2=13.3(1) cm−1 and |D|=11.3(4) cm−1 (for 1) and g=2.206(4), J1=1.0(1) cm−1, J2=7.8(1) cm−1 and |D|=8.7(2) cm−1 (for 2). The large anisotropy, high ground spin state (arising from the ferromagnetic coupling) and the good isolation of the clusters provided by the Schiff base ligands, give rise to the first examples of field‐induced single‐molecule magnets (FI−SMM) in Ni4O4 clusters and to the highest energy barrier reported to date in a Ni4O4 cluster. [ABSTRACT FROM AUTHOR]

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1–15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210–596 m2·g−1, an apparent density of 0.403–0.740 cm3·g−1 and a porosity of 60–78%. The actual cobalt content in the aerogels was 0.01–1.50 mmol per 1 g of SiO2, which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO3)2], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K. [ABSTRACT FROM AUTHOR]

The conditions for achieving the maximal unquenched orbital angular momentum L = 3 and the highest magnetic anisotropy in mononuclear 3d complexes with axial coordination symmetry are examined in terms of the ligand field theory. It is shown that, apart from the known linear two-coordinate 3d7 complex CoII(C(SiMe2ONaph)3)2 characterized by record magnetic anisotropy and single-molecule magnet (SMM) performance (with the largest known spin-reversal barrier Ueff = 450 cm−1), the maximal orbital angular momentum L = 3 can also be obtained in linear two-coordinate 3d2 complexes (V3+, Cr4+) and in trigonal-prismatic 3d3 (Cr3+, Mn4+) and 3d8 (Co+, Ni2+) complexes. A comparative assessment of the SMM performance of the 3d2, 3d3 and 3d8 complexes indicates that they are unlikely to compete with the record linear complex CoII(C(SiMe2ONaph)3)2, whose magnetic anisotropy is close to the physical limit for a 3d metal. [ABSTRACT FROM AUTHOR]

Multifunctional lanthanide complexes have been studied extensively owing to their promising applications in information storage, luminescence sensors and magneto‐optical devices, etc. Here, we report the facile synthesis of two discrete highly thermally stable lanthanide compounds, Ln(hfac)3(TPE‐tz) (Ln=Eu, Dy), by the reaction of the AIE‐active organic ligand with Ln(III) β‐diketonate precursor. Due to different energy gaps between the triplet state of the ligand and the accepted level of Ln(III) ions, Eu(hfac)3(TPE‐tz) exhibited remarkably enhanced luminescence intensity upon aggregation, i. e. a typical AIE behavior, while Dy(hfac)3(TPE‐tz) displayed weak characteristic emission bands of Dy(III) ions. In addition, Dy(hfac)3(TPE‐tz) showed field‐induced SMM behavior. This work shows that careful choice of auxiliary ligands paves the way for the construction of multifunctional lanthanide smart materials. [ABSTRACT FROM AUTHOR]

A novel multi-channel barcode module was developed by using chiral co-crystals which contain field-induced SMM behavior and different emission bands. The chiral co-crystals [Zn(H2L)Dy(DBM)2]4(ClO4)4⋅9CH3OH⋅H2O (1a) and [Zn(H2L)Dy(DBM)2]4(ClO4)4⋅8CH3OH⋅0.5H2O (1b) (H4L = 2,2′-[1,2-ethanediylbis[(hydroxyethylimino)methylene]]bis[6-methoxy-4-methyl-phenol], HDBM = dibenzoylmethane) were obtained through one-pot reaction of ZnII and DyIII with the achiral ligands H4L and HDBM. X-ray single crystal diffraction and CD spectroscopy confirmed that they are enantiomers crystallized in P43 (1a) and P41 (1b), both consisting of two ∆-[Zn(H2L)Dy(DBM)2]+ cations, two Λ-[Zn(H2L)Dy(DBM)2]+ cations and four (ClO4)− anions. The presence of DyIII ions endow them with the property of field-induced slow magnetic relaxation. The relatively low energy barrier of 35.0(9) K for complex 1 may be due to the poor axiality of the ligand field caused by the long Dy-Ophenoxy bond lengths and the small Ophenoxy-Dy-Ophenoxy bond angles. Moreover, when the organic ligands H4L (λex = 350 nm) and DyIII (λex = 420 nm) are excited, different emission spectra are observed. [ABSTRACT FROM AUTHOR]

Three novel hexanuclear DyIII complexes with polyhydroxy Schiff-base ligands have been prepared under ambient conditions and structurally characterized. Each of the hexanuclear complexes is constructed with Dy 3 triangular motifs as building blocks, and the six DyIII ions are arranged in three different conformations. [Display omitted] Three novel hexanuclear DyIII complexes supported by polyhydroxy Schiff-base ligands, [Dy 6 (hmc) 3 (μ -acac) 2 (acac) 3 (μ 3 -OH) 4 (H 2 O) 2 ]·2MeCN (1 ·2MeCN), [Dy 6 K 2 (hmc) 3 (μ -CO 3) 6 (μ 3 -CO 3) 4 (H 2 O) 2 ]·8MeOH (2 ·8MeOH) and [Dy 6 (hmc) 3 (μ -OAc) 6 (μ 3 -OH) 3 (H 2 O) 3 ] (3) (H 3 hmc: 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonhydrazide), have been prepared and structurally characterized by single-crystal X-ray diffraction, elemental analysis, and IR spectroscopy. Each of the hexanuclear complexes is constructed from triangular Dy 3 building blocks, with the six DyIII ions are arranged in three different conformations. The magnetic properties of three dinuclear DyIII complexes have also been investigated (Fig. S2). The frequency-dependent ac susceptibility is indicative of Single-Molecule Magnet behavior without and/or with optimum dc field for complexes 2 and 3. [ABSTRACT FROM AUTHOR]

• Two dysprosium complexes Dy 4 and Dy 5 based on hydrazone Schiff-base ligand were synthesized, and their structures could be regulated by controlling temperature. • Complex Dy 4 is a typical field-induced single-molecule magnet with an effective energy barrier U eff of 42.9 K under 1 kOe dc field. Complex Dy 5 is a zero dc field single-molecule magnet with an effective energy barrier U eff of 4.18 K. Two dysprosium complexes [Dy 4 (H 2 L) 6 ]⋅4H 2 O (Dy 4) and [Dy 5 (H 2 L)(HL) 2 (L)(µ 3 OH) 2 Cl(H 2 O)(MeCN) 2 ]⋅4MeOH⋅7H 2 O (Dy 5) (H 4 L = (N',N'''E,N',N'''E)-N',N'''-(pyridine-2,6-diylbis(methanylylidene))bis(2-hydroxybenzohydrazide)) based on hydrazone Schiff-base ligand were synthesized, which could be regulated by controlling temperature (Dy 4 , below 293 K and Dy 5 , over 308 K). Magnetic studies show that complex Dy 4 is a typical field-induced single-molecule magnet with an effective energy barrier (U eff) of 42.9 K under 1 kOe dc field. Complex Dy 5 is a zero dc field single-molecule magnet with an effective energy barrier (U eff) of 4.18 K. The results indicate the synthesis of lanthanide complexes is sensitive to substitute of ligand and temperature. Two novel compounds, Dy 4 and Dy 5 , were synthesized by using hydrazone Schiff-base ligand and dysprosium ions. Their structures and single-molecule magnet properties can be regulated by synthetic temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

The hexacoordinate Co(II) complex [Co(neo)2(cin)][BPh4]·½Me2CO (1·½Me2CO) containing trans-cinnamic acid (Hcin) and neocuproine (neo) was prepared. The compound 1·½Me2CO was characterized via single-crystal X-ray analysis, FT-IR spectroscopy, and magnetic measurements. The coordination polyhedron of the complex cation adopts a deformed octahedron shape, and cinnamate exhibits a bidentate mode of coordination, which is unusual for mononuclear Co(II) cinnamate complexes. The analysis of DC magnetic measurements with zero-field splitting (ZFS) spin Hamiltonian revealed large magnetic anisotropy defined by the axial ZFS parameter D = +53.2 cm−1. AC susceptibility measurements revealed the slow relaxation of magnetization under the applied field; thus, 1·½Me2CO behaves as a field-induced single-molecule magnet. The analysis of magnetic properties was also supported by CASSCF/NEVPT2 calculations.

Abstract 2D metal–organic frameworks have been recently proposed as a flexible platform for realizing new functional materials including quantum phases. Here, we present a method to create metal‐organic dimer complexes by on‐surface assembly on a metal substrate using low‐temperature scanning tunneling microscopy (STM) and spectroscopy (STS). We demonstrate that a dimer of Mn‐Phthalocyanine (MnPc)2 on a Ag(111) surface can be switched between two stable configurations upon a small conformational change controlled by STM manipulation. By means of density‐functional theory calculations, it is found that the two conformations correspond to an antiferromagnetic (AFM) and a ferromagnetic (FM) state respectively. Directly coordinated Mn atoms of the dimer lead to an AFM‐coupling whereas indirectly coordinated (shifted) Mn atoms lead to a FM‐coupling. Rarely seen in a molecular‐dimers with transition‐metal atoms, the FM‐AFM‐FM transition is thus readily on‐surface accessible. Furthermore, the two configurations of the switch are easily identified by their Kondo states, opening interesting routes in terms of both, writing (FM versus AFM states) and reading. These results pave the experimental route toward dimer‐based materials with complex magnetic structures of potential interest for application in spintronics, logics and computing.

Molecular crystals acting as temperature sensors, designed for multiple measurement techniques, can be a promising pathway for self‐calibrating thermometers. The molecular assemblies [DyxIIIY1–xIII(phen)2(μ‐OH)2(H2O)2]·[AuI(SCN)2]2·phen·0.5MeCN·0.5H2O (x = 0, 0.1, 0.02; phen = 1,10‐phenanthroline) which contain weakly bonded lanthanide(III) and Au(I) metal complexes are reported. They have Raman scattering in the low‐frequency (LF) region with sharp peaks, one of the prerequisites to design Raman thermometers. The Raman thermometric behaviors are characterized by three vibrational bands, and their thermal sensitivity is compared with their emission thermometric ability. The LF phonon linked with the Au···Au vibration helps increase the thermometric sensitivity of emission and Raman thermometers. Additionally, magnetically diluted complexes containing both Dy3+ and Y3+ ions are prepared to demonstrate the effect of temperature sensing capability through Raman and emission spectroscopy among isostructural mixed‐metal materials. Compounds are immersed inside various benchtop solvents to unravel the robustness and functioning of Raman thermometers. Furthermore, they reveal single‐molecule magnet properties, which disclose the effect of LF phonons on the spin relaxation process. Therefore, the reported molecular materials are Raman and luminescent thermometers, and they contain a molecular magnetic center with thiocyanidoaurate ions playing a critical role due to their emissive and Raman activities. [ABSTRACT FROM AUTHOR]

Schiff base ligands with multiple chelating coordination sites are usually able to quickly capture lanthanide metal ions to form complexes, and it is difficult to twist and construct helical chains. In this work, we used 2-hydroxy-1-naphthaldehyde, propylenediamine, and Ln(NO3)3·6H2O to react at 80 °C in solvothermal to obtain chains [Ln = Dy (1); Ln = Gd (2)] with a helical structure. It is worth noting that 2-hydroxy-1-naphthaldehyde and propylenediamine undergo an in situ reaction under one-pot conditions to form ligand 1,1′-((1E,1′E)-(propane-1,3-diylbis(azaneylylidene))bis(methaneylylidene))bis(naphthalen-2-ol) (H2L). The ligand (L)2− bridges the two metal center Ln(III) ions with a monodentate, causing it to twist into an "S" shape and further form a helical chain. In addition, the independent unit of the helical chain is a single core, and its metal center is in the O9 coordination environment provided by the ligand and the end group coordination NO3− ions. What's more noteworthy is that chain 1 exhibits single-molecule magnet (SMM) behavior, and its SMM performance is significantly improved under the DC field induction condition of 600 Oe. By Debye model fitting, the effective energy barrier of 1 is 17.8 K, and the relaxation time is 2.4 × 10–6 s. The magnetocaloric effect test of chain 2 is further carried out. When ΔH = 7 T and T = 2 K, its − ΔSm reaches the maximum value of 16.19 J K−1 kg−1. [ABSTRACT FROM AUTHOR]

We report the synthesis and structures of two base‐free alkoxide dysprosium(III) complexes of formula [Dy(L1)2(μ‐η6:η1‐Ph)2BPh2] ⋅ CH2Cl2 (1) and [Dy(L2)2(μ‐η6:η1‐Ph)2BPh2] ⋅ 3(C7H8) (2) featuring a tetraphenylborate binding (L1=2,6‐dibenzhydryl‐4‐(tert‐butyl)phenolate, L2=tri(naphtalen‐1‐yl)methanolate). Investigations of the magnetic properties for 1 in line with theoretical calculations reveal the occurrence of a field‐induced slow relaxation of the magnetization. [ABSTRACT FROM AUTHOR]

Four mononuclear complexes were synthesized through simple self‐assembly reactions, [Dy(L1)2(NO3)H2O] (1), [Tb(L1)2(NO3)MeOH] (2), [Ho(L1)2(NO3)H2O] ⋅ 5.5H2O (3) (HL1=4‐bromo‐2‐((quinolin‐8‐ylimino)methyl)phenol), and [Dy(L2)2(NO3)H2O] (4) (HL2=2,4‐dibromo‐6‐((quinolin‐8‐ylimino)methyl)phenol). They are characterized by their structures and magnetic properties. The magnetic data show that the Dy clusters all have obvious frequency‐dependent magnetic behavior and slow magnetic relaxation effects. The complex 1 under an external dc field with the anisotropic barrier of 14.41 K and pre‐exponential factor τ0=2.70×10−6 s, the complex 4 under an external dc field with the anisotropic barrier of 64.36 K and pre‐exponential factor τ0=2.38×10−7 s. [ABSTRACT FROM AUTHOR]

The first neutral 0D and 1D heterometallic assemblies based on orbitally degenerate heptacyanidorhenate(IV) were prepared and structurally characterized. An analysis of the magnetic data of polycrystalline samples showed that both compounds display slow magnetization relaxation at temperatures below 5 K. The very low temperature measurements of the magnetization on the single crystals demonstrate that for the 1D compound {[Mn(SB2+)Re(CN)7]·7H2O}n (1) and the 0D complex [Mn(SB2+)(H2O)Re(CN)7]·2H2O (2), the hysteresis loops open just below 2.2 and 1.8 K, respectively. Thus, heterometallic polymer 1 is the first single-chain magnet involving a pentagonal bipyramidal [ReIV(CN)7]3− synthon, and the binuclear complex 2 represents a single-molecule magnet. [ABSTRACT FROM AUTHOR]

We report the synthesis of heteroleptic dysprosium complexes of the 1,2,4-tris(trimethylsilyl)cyclopentadienyl ligand (Cp‴={C5H2(SiMe3)3-1,2,4}), and diamagnetic yttrium analogues, by salt metathesis protocols from KCp‴ and molecular lanthanoid halide or borohydride precursors: [{Ln(Cp‴)2(μ-Cl)2K}2]∞ (1-Ln ; Ln = Y, Dy), [Ln(Cp‴)2(THF)(Cl)] (2-Ln ; Ln = Y, Dy), [Y(Cp‴)2(η3-C3H5)] (3-Y), [Y(Cp‴)(BH4)2(THF)] (4-Y), [Dy(Cp‴)(BH4)(μ-BH4)]4 (5-Dy) and [Ln(Cp‴)2(BH4)] (6-Ln ; Ln = Y, Dy); several crystals of [Dy(Cp‴)2(BH4)(THF)] (7-Dy) formed on one occasion during the isolation of 6-Dy. Efforts to prepare the isolated lanthanoid metallocenium cations [Ln(Cp‴)2]+ for Y and Dy were not successful by the anion abstraction methods investigated herein; however, several crystals of the contact ion-pair complex [Y(Cp‴)2{(μ-Ph)2BPh2}] (8-Y) formed from the reaction of 3-Y with [NEt3H][BPh4]. On one occasion during the preparation of 3-Y we isolated several crystals of [Mg(Cp‴)(THF)(μ-Cl)]2. Complexes 1–6 and [NEt3H][BPh4] were all structurally authenticated by single crystal XRD and characterised by IR spectroscopy and elemental analysis, with magnetic susceptibility for dysprosium complexes determined by the Evans method, and yttrium analogues studied by multinuclear NMR spectroscopy; complexes 7-Dy , 8-Y , and [Mg(Cp‴)(THF)(μ-Cl)]2 were characterised by single crystal XRD only. The magnetic properties of 5-Dy were probed by SQUID magnetometry and ab initio calculations. We report the synthesis and characterisation of a series of heteroleptic yttrium and dysprosium 1,2,4-tris(trimethylsilyl)cyclopentadienyl complexes containing halide, borohydride or allyl co-ligands. Attempts to abstract co-ligands and install weakly coordination anions to generate lanthanoid metallocenium cations were unsuccessful, which we attribute to side reactions with 1,2,4-tris(trimethylsilyl)cyclopentadienyl rings. [ABSTRACT FROM AUTHOR]

The introduction of the cerium(III) analogue (1-Ce, Ln = Ce) of (tert-butoxido)chloridopentakis(tetrahydrofuran)lanthanide(III) tetraphenylborate tetrahydrofuran disolvate, [Ln{OC(CH 3 ) 3 }Cl(C 4 H 8 O) 5 ][B(C 6 H 5 ) 4 ]·2C 4 H 8 O or [Ln(O t Bu)Cl(THF) 5 ](BPh 4 )·2THF (1-Ln) has been achieved with a structural comparison between the existing solid-state structures of other rare earth analogues and the title compound at 100 and 180 K. The cation in 1-Ce is targeted as the cerium(III) ion possesses the criteria to exhibit slow magnetic relaxation in axial point-charge crystal fields, akin to the dysprosium(III) ion in 1-Dy. AC magnetic susceptibility experiments reveal no such behaviour for 1-Ce, putting the viability of cerium-based SMMs into question.

The pursuit of molecule-based magnetic memory materials contributes significantly to high-density information storage research in the frame of the ongoing information technologies revolution. Remarkable progress has been achieved in both transition metal (TM) and lanthanide based single-molecule magnets (SMMs). Notably, six-coordinated Co II SMMs hold particular research significance owing to the economic and abundant nature of 3d TM ions compared to lanthanide ions, the substantial spin-orbit coupling of Co II ions, the potential for precise control over coordination geometry, and the air-stability of coordination-saturated structures. In this review, we will summarize the progress made in six-coordinated Co II SMMs, organized by their coordination geometry and molecular structure similarity. Valuable insights, principles, and new mechanism gleaned from this research and remaining issues that need to be addressed will also be discussed to guide future optimization., (© 2024 Wiley-VCH GmbH.)

The reaction between the ((E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide) (H2opch) ligand and the metallo-precursor [Dy(hfac)3]·2H2O led to the formation of an homometallic coordination complex with the formula [Dy2(hfac)3(H2O)(Hopch)2][Dy(hfac)4] (1). In presence of both [Dy(hfac)3] 2H2O and the Fe(II) salt, the heterobimetallic tetranuclear [FeDy3(hfac)8(H2O)2(opch)2] (2) was isolated, while the addition of the co-ligand 1,2-Bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H2bmh) led to the formation of two heterobimetallic tetranuclear complexes with the formula [Fe3Dy(hfac)6(opch)2(H2bmh)] C6H14 (3) C6H14 and [Fe2Dy2(hfac)7(opch)2(H2bmh)] 0.5C7H16 (4) 0.5C7H16. Single crystal X-ray diffraction and dc magnetic investigation demonstrated that 3 and 4 involved the iron center in the +II and +III oxidation states. Dynamic magnetic measurements highlighted the single-molecule magnet behavior of 1 and 2 in a zero applied dc field primarily due to the ferromagnetic interactions taking place in these compounds.