1,2-Diaza-4-phospholide complexes of chromium(ii): dipotassium organochromates behaving as single-molecule magnets

Jing Su; Lei Yin; Zhongwen Ouyang; Zhenxing Wang; Wenjun Zheng

doi:10.1039/d0dt00878h

Slow Relaxation of the Magnetization in Anilato-Based Dy(III) 2D Lattices

Molecules ◽

10.3390/molecules26041190 ◽

2021 ◽

Vol 26 (4) ◽

pp. 1190

Author(s):

Samia Benmansour ◽

Antonio Hernández-Paredes ◽

María Bayona-Andrés ◽

Carlos J. Gómez-García

Keyword(s):

Magnetic Properties ◽

Single Molecule ◽

Related Compound ◽

Interlayer Space ◽

Magnetic Measurements ◽

Three Dimensional ◽

Slow Relaxation ◽

Two Dimensional ◽

Single Molecule Magnets ◽

Solvent Molecules

The search for two- and three-dimensional materials with slow relaxation of the magnetization (single-ion magnets, SIM and single-molecule magnets, SMM) has become a very active area in recent years. Here we show how it is possible to prepare two-dimensional SIMs by combining Dy(III) with two different anilato-type ligands (dianions of the 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone: C6O4X22−, with X = H and Cl) in dimethyl sulfoxide (dmso). The two compounds prepared, formulated as: [Dy2(C6O4H2)3(dmso)2(H2O)2]·2dmso·18H2O (1) and [Dy2(C6O4Cl2)3(dmso)4]·2dmso·2H2O (2) show distorted hexagonal honeycomb layers with the solvent molecules (dmso and H2O) located in the interlayer space and in the hexagonal channels that run perpendicular to the layers. The magnetic measurements of compounds 1, 2 and [Dy2(C6O4(CN)Cl)3(dmso)6] (3), a recently reported related compound, show that the three compounds present slow relaxation of the magnetization. In compound 1 the SIM behaviour does not need the application of a DC field whereas 2 and 3 are field-induced SIM (FI-SIM) since they show slow relaxation of the magnetization when a DC field is applied. We discuss the differences observed in the crystal structures and magnetic properties based on the X group of the anilato ligands (H, Cl and Cl/CN) in 1–3 and in the recently reported derivative [Dy2(C6O4Br2)3(dmso)4]·2dmso·2H2O (4) with X = Br, that is also a FI-SIM.

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Formation of a nonanuclear copper(II) cluster with 3,5-dimethylpyrazolate starting from an NHC complex of copper(I) chloride

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989020011275 ◽

2020 ◽

Vol 76 (9) ◽

pp. 1486-1490

Author(s):

Christopher A. Dodds ◽

Alan R. Kennedy

Keyword(s):

Hydrogen Bonds ◽

Single Molecule ◽

Chloride Ion ◽

Single Molecule Magnets ◽

Apical Position ◽

Tetrahedral Geometry ◽

Imidazolium Cation ◽

Research Fields ◽

Square Planar

The complete nonanuclear cluster in bis[1,3-bis(2,6-dimethylphenyl)imidazolium] di-μ-chlorido-tetrachloridooctakis(μ-3,5-dimethylpyrazolato)hexa-μ3-hydroxido-nonacopper(II) chloroform disolvate, [HIXy]2[Cu9(μ-pz*)8(μ3-OH)6(μ2-Cl)2Cl4]·2CHCl3 or (C19H21N2)2[Cu9(C5H7N2)8Cl6(OH)6]·2CHCl3, where pz* is the 3,5-dimethylpyrazolyl anion, C5H7N2 −, and HIXy is the 1,3-bis(2,6-dimethylphenyl)imidazolium cation, C19H21N2 +, is generated by a crystallographic centre of symmetry with a square-planar CuII ion bound to four μ3-OH ions lying on the inversion centre. Of the four remaining unique CuII atoms, three adopt CuN2O2Cl square-pyramidal coordination geometries with the chloride ion in the apical position and one has a distorted CuN2OCl tetrahedral geometry. The dianionic nonanuclear core can be described as a 24-membered [CuNN]8 ring that contains a Cu9O6Cl6 core. The cluster features three intramolecular O—H...Cl hydrogen bonds. In the crystal, weak C—H...N and C—H...Cl interactions link the components. Polynuclear paramagnetic clusters of this type are of considerable interest due to their relevance to both the bioinorganic and single-molecule magnets research fields.

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M–H–BR3 and M–Br–BR3 interactions in rhodium and nickel complexes of an ambiphilic phosphine–thioether–borane ligand

Canadian Journal of Chemistry ◽

10.1139/cjc-2017-0758 ◽

2018 ◽

Vol 96 (5) ◽

pp. 484-491 ◽

Cited By ~ 1

Author(s):

Bradley E. Cowie ◽

David J.H. Emslie

Keyword(s):

Crystal Structure ◽

Room Temperature ◽

Magnetic Measurements ◽

Nickel Complexes ◽

Planar Geometry ◽

Nmr Spectrum ◽

X Ray ◽

H Nmr ◽

Square Planar ◽

Hydride Ligand

Reaction of [Rh(μ-Cl)(CO)(TXPB)] (1; TXPB = 2,7-di-tert-butyl-5-diphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene) with NaBH4 yielded square planar [Rh(μ-H)(CO)(TXPB)] (2) in which the hydride ligand bridges between rhodium and the borane unit of TXPB. The Rh–H, Rh–B, and Rh–Cipso distances are short at 1.84(5), 2.456(6), and 2.568(5) Å, respectively, whereas the B–H bond, 1.59(6) Å, falls at the longer end of the usual range. Compound 2 is compared with the previously reported series of rhodium TXPB complexes: [RhX(CO)(TXPB)] {X = F (3), Cl (1), Br (4), I (5)}. Compound 4 in this series features the only crystallographically characterized example of an M–Br–BR3 interaction, and to expand this area, [NiBr(μ-Br)(TXPB)] (6) was prepared via the reaction of [NiBr2(dme)2] (dme = 1,2-dimethoxyethane) with TXPB. An X-ray crystal structure of light purple 6 revealed a square-planar geometry with a strong B–Br interaction {B–Br = 2.311(6) Å; ∑(C–B–C) = 344.5(7)°}. An 11B NMR chemical shift of 23 ppm was observed for 6, indicating that an appreciable B–Br interaction is maintained in solution. No signals were observed in the 31P{1H} NMR spectrum at room temperature, whereas a broadened 31P signal was observed at −20 °C, evolving into a sharp singlet at −67 °C. This behaviour suggests that at room temperature, square planar 6 exists in equilibrium with a paramagnetic tetrahedral isomer, present at a level below that detectable through Evans magnetic measurements.

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Insensitivity of Magnetic Coupling to Ligand Substitution in a Series of Tetraoxolene Radical-Bridged Fe2 Complexes

10.26434/chemrxiv.11400465.v1 ◽

2019 ◽

Author(s):

Agnes Thorarindottir ◽

Ragnar Bjornsson ◽

T. David Harris

Keyword(s):

Single Molecule ◽

Magnetic Measurements ◽

Variable Temperature ◽

Magnetic Coupling ◽

Ligand Substitution ◽

X Ray Diffraction ◽

Single Molecule Magnets ◽

Susceptibility Data ◽

Bridging Ligand ◽

Exchange Constants

The elucidation of magnetostructural correlations between bridging ligand substitution and strength of magnetic coupling is essential to the development of high-temperature molecule-based magnetic materials. Toward this end, we report the series of tetraoxolene-bridged FeII2 complexes [(Me3TPyA)2Fe2(RL)]n+ (Me3TPyA = tris(6-methyl-2-pyridylmethyl)amine; n = 2: OMeLH2 = 3,6-dimethoxy-2,5-dihydroxo-1,4-benzoquinone, ClLH2 = 3,6-dichloro-2,5-dihydroxo-1,4-benzoquinone, Na2[NO2L] = sodium 3,6-dinitro-2,5-dihydroxo-1,4-benzoquinone; n = 0: SMe2L = 3,6-bis(dimethylsulfonium)-2,5-dihydroxo-1,4-benzoquinone diylide) and their one-electron-reduced analogues. Variable-temperature dc magnetic susceptibility data reveal the presence of weak ferromagnetic superexchange between FeII centers in the oxidized species, with exchange constants of J = +1.2(2) (R = OMe, Cl) and +0.3(1) (R = NO2, SMe2) cm−1. In contrast, X-ray diffraction, cyclic voltammetry, and Mössbauer spectroscopy establish a ligand-centered radical in the reduced complexes. Magnetic measurements for the radical-bridged species reveal the presence of strong antiferromagnetic metal–radical coupling, with J = −57(10), −60(5), −58(6), and −65(8) cm−1 for R = OMe, Cl, NO2, and SMe2, respectively. The minimal effects of substituents in the 3- and 6-positions of RLx−• on the magnetic coupling strength is understood through electronic structure calculations, which show negligible spin density on the substituents and associated C atoms of the ring. Finally, the radical-bridged complexes are single-molecule magnets, with relaxation barriers of Ueff = 50(1), 41(1), 38(1), and 33(1) cm−1 for R = OMe, Cl, NO2, and SMe2, respectively. Taken together, these results provide the first examination of how bridging ligand substitution influences magnetic coupling in semiquinoid-bridged compounds, and they establish design criteria for the synthesis of semiquinoid-based molecules and materials.

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Field-Induced Single-Molecule Magnets of Dysprosium Involving Quinone Derivatives

Magnetochemistry ◽

10.3390/magnetochemistry7020024 ◽

2021 ◽

Vol 7 (2) ◽

pp. 24

Author(s):

Konstantin Martyanov ◽

Jessica Flores Gonzalez ◽

Sergey Norkov ◽

Bertrand Lefeuvre ◽

Vincent Dorcet ◽

...

Keyword(s):

Hydrogen Bonds ◽

Single Molecule ◽

Magnetic Relaxation ◽

Magnetic Measurements ◽

Single Molecule Magnets ◽

Single Molecule Magnet ◽

X Ray ◽

Tert Butyl ◽

Raman Process ◽

Coordination Reaction

The coordination reaction of the [Dy(hfac)3(H2O)2] units (hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonate) with the two quinone-based derivatives 4,7-di-tert-butyl-2-(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)benzo[d][1,3]dithiole-5,6-dione (L1) and 7,8-dithiabicyclo[4.2.0]octa-1,5-diene-3,4-dione,2,5bis(1,1-dimethylethyl) (L2) led respectively to the complexes [Dy(hfac)3(H2O)(L1)] (1) and [Dy(hfac)3(H2O) (L2)]⋅(C6H14)(CH2Cl2) (2)⋅(C6H14)(CH2Cl2). X-ray structures on single crystal of 1 and 2⋅(C6H14)(CH2Cl2) revealed the coordination of the DyIII on the bischelating oxygenated quinone site and the formation of dimeric species through hydrogen bonds. Ac magnetic measurements highlighted field-induced single-molecule magnet behavior with magnetic relaxation through a Raman process.

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A Series of Novel Pentagonal-Bipyramidal Erbium(III) Complexes with Acyclic Chelating N3O2 Schiff-Base Ligands: Synthesis, Structure, and Magnetism

Molecules ◽

10.3390/molecules26226908 ◽

2021 ◽

Vol 26 (22) ◽

pp. 6908

Author(s):

Tamara A. Bazhenova ◽

Vyacheslav A. Kopotkov ◽

Denis V. Korchagin ◽

Yuriy V. Manakin ◽

Leokadiya V. Zorina ◽

...

Keyword(s):

Experimental Study ◽

Magnetic Properties ◽

Schiff Base ◽

Theoretical Analysis ◽

Single Molecule ◽

Theoretical Study ◽

Magnetic Measurements ◽

Single Molecule Magnets ◽

Schiff Base Ligands ◽

Axial Ligands

A series of six seven-coordinate pentagonal-bipyramidal (PBP) erbium complexes, with acyclic pentadentate [N3O2] Schiff-base ligands, 2,6-diacetylpyridine bis-(4-methoxybenzoylhydrazone) [H2DAPMBH], or 2,6-diacethylpyridine bis(salicylhydrazone) [H4DAPS], and various apical ligands in different charge states were synthesized: [Er(DAPMBH)(C2H5OH)Cl] (1); [Er(DAPMBH)(H2O)Cl]·2C2H5OH (2); [Er(DAPMBH)(CH3OH)Cl] (3); [Er(DAPMBH)(CH3OH)(N3)] (4); [(Et3H)N]+[Er(H2DAPS)Cl2]− (5); and [(Et3H)N]+[Y0.95Er0.05(H2DAPS)Cl2]− (6). The physicochemical properties, crystal structures, and the DC and AC magnetic properties of 1–6 were studied. The AC magnetic measurements revealed that most of Compounds 1–6 are field-induced single-molecule magnets, with estimated magnetization energy barriers, Ueff ≈ 16–28 K. The experimental study of the magnetic properties was complemented by theoretical analysis based on ab initio and crystal field calculations. An experimental and theoretical study of the magnetism of 1–6 shows the subtle impact of the type and charge state of the axial ligands on the SMM properties of these complexes.

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Synthetic, Spectroscopic and Biocidal Aspects of Heterobimetallic Complexes Comprising Platinum(II) and a Group Four or Fourteen Element

Metal-Based Drugs ◽

10.1155/mbd.2000.1 ◽

2000 ◽

Vol 7 (1) ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

Kripa Sharma ◽

R. V. Singh

Keyword(s):

Molecular Weight ◽

Magnetic Measurements ◽

Pathogenic Fungi ◽

Molar Ratio ◽

Planar Geometry ◽

Conductivity Data ◽

Heterobimetallic Complexes ◽

Square Planar ◽

Growth Inhibiting

Heterobimetallic complexes with varying amines have been synthesized by the reaction of [Pt(C2H8N2)2]Cl2 with group four or fourteen organometallic dichlorides, viz., R2MCl2 and Cp2M'Cl2 in a 1:2 molar ratio in MeOH (where M=Si or Sn, M'= Ti or Zr and R=Ph or Me). These complexes have been characterized by elemental analysis, molecular weight determinations, magnetic measurements, conductance, IR, H1 NMR and electronic spectra. The spectral data suggest a square planar geometry for all the complexes. Conductivity data suggest that they behave as electrolytes. These monometallic precursors along with their complexes have been screened in vitro against a number of pathogenic fungi and bacteria to assess their growth inhibiting potential.

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Low-Coordinate Dinuclear Dysprosium(III) Single Molecule Magnets Utilizing LiCl as Bridging Moieties and tris(amido)amine as Blocking Ligands

Magnetochemistry ◽

10.3390/magnetochemistry7090125 ◽

2021 ◽

Vol 7 (9) ◽

pp. 125

Author(s):

Maria Brzozowska ◽

Gabriela Handzlik ◽

Mikolaj Zychowicz ◽

Dawid Pinkowicz

Keyword(s):

Single Molecule ◽

Magnetic Measurements ◽

Magnetic Hysteresis ◽

Magnetic Hysteresis Loop ◽

Magnetic Interactions ◽

Ac Magnetic Susceptibility ◽

Easy Magnetization ◽

Single Molecule Magnets ◽

Slow Magnetic Relaxation ◽

Dysprosium Complex

A low-coordinate dinuclear dysprosium complex {[Dy(N3N)(THF)][LiCl(THF)]}2 (Dy2) with a double bridging ‘LiCl’ moiety and tris(amido)amine (N3N)3- anions as a blocking ligand is synthesized and characterized structurally and magnetically. Thanks to the use of the chelating blocking ligand (N3N)3− equipped with large steric –SiMe3 groups, the coordination sphere of both DyIII ions is restricted to only six donor atoms. The three amido nitrogen atoms determine the orientation of the easy magnetization axes of both DyIII centers. Consequently, Dy2 shows slow magnetic relaxation typical for single molecule magnets (SMMs). However, the effective energy barrier for magnetization reversal determined from the AC magnetic susceptibility measurements is much lower than the separation between the ground and the first excited Kramers doublet based on the CASSCF ab initio calculations. In order to better understand the possible influence of the anticipated intramolecular magnetic interactions in this dinuclear molecule, its GdIII-analog {[Gd(N3N)(THF)][LiCl(THF)]}2 (Gd2) is also synthesized and studied magnetically. Detailed magnetic measurements reveal very weak antiferromagnetic interactions in Gd2. This in turn suggests similar antiferromagnetic interactions in Dy2, which might be responsible for its peculiar SMM behavior and the absence of the magnetic hysteresis loop.

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Magnetic Behaviour of Mn12-Stearate Single-Molecule Magnets Immobilized on the Surface of 300 nm Spherical Silica Nanoparticles

Materials ◽

10.3390/ma13112624 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2624 ◽

Cited By ~ 3

Author(s):

Magdalena Laskowska ◽

Oleksandr Pastukh ◽

Piotr Konieczny ◽

Mateusz Dulski ◽

Marcin Zalsiński ◽

...

Keyword(s):

Silica Nanoparticles ◽

Single Molecule ◽

Silica Surface ◽

Magnetic Measurements ◽

Magnetic Behaviour ◽

Silica Spheres ◽

Squid Magnetometry ◽

Single Molecule Magnets ◽

Transmission Electron ◽

Spherical Silica

The magnetic behaviour of Mn 12 -stearate single-molecule magnets (SMMs) ([ Mn 12 O 12 ( CH 3 ( CH 2 ) 16 CO 2 ) 16 ] · 2 CH 3 COOH · 4 H 2 O ) on the surface of 300 nm spherical silica nanoparticles were investigated. The SMMs were bonded at the silica surface with the assumed number of anchoring points, which influenced on their degree of freedom and distribution. In order to check the properties of Mn 12 -stearate molecules separated on the silica surface, and check their interactions, the samples containing four different concentration of spacers per single anchoring unit and variously bonded Mn 12 -stearate particles were prepared. The materials have been examined using Raman spectroscopy, transmission electron microscopy, and SQUID magnetometry. The results of magnetic measurements showed a correlation between the way of single-molecule magnets immobilization onto the silica spheres and the magnetic properties of the obtained hybrid materials.

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Insensitivity of Magnetic Coupling to Ligand Substitution in a Series of Tetraoxolene Radical-Bridged Fe2 Complexes

10.26434/chemrxiv.11400465 ◽

2019 ◽

Author(s):

Agnes Thorarindottir ◽

Ragnar Bjornsson ◽

T. David Harris

Keyword(s):

Single Molecule ◽

Magnetic Measurements ◽

Variable Temperature ◽

Magnetic Coupling ◽

Ligand Substitution ◽

X Ray Diffraction ◽

Single Molecule Magnets ◽

Susceptibility Data ◽

Bridging Ligand ◽

Exchange Constants

The elucidation of magnetostructural correlations between bridging ligand substitution and strength of magnetic coupling is essential to the development of high-temperature molecule-based magnetic materials. Toward this end, we report the series of tetraoxolene-bridged FeII2 complexes [(Me3TPyA)2Fe2(RL)]n+ (Me3TPyA = tris(6-methyl-2-pyridylmethyl)amine; n = 2: OMeLH2 = 3,6-dimethoxy-2,5-dihydroxo-1,4-benzoquinone, ClLH2 = 3,6-dichloro-2,5-dihydroxo-1,4-benzoquinone, Na2[NO2L] = sodium 3,6-dinitro-2,5-dihydroxo-1,4-benzoquinone; n = 0: SMe2L = 3,6-bis(dimethylsulfonium)-2,5-dihydroxo-1,4-benzoquinone diylide) and their one-electron-reduced analogues. Variable-temperature dc magnetic susceptibility data reveal the presence of weak ferromagnetic superexchange between FeII centers in the oxidized species, with exchange constants of J = +1.2(2) (R = OMe, Cl) and +0.3(1) (R = NO2, SMe2) cm−1. In contrast, X-ray diffraction, cyclic voltammetry, and Mössbauer spectroscopy establish a ligand-centered radical in the reduced complexes. Magnetic measurements for the radical-bridged species reveal the presence of strong antiferromagnetic metal–radical coupling, with J = −57(10), −60(5), −58(6), and −65(8) cm−1 for R = OMe, Cl, NO2, and SMe2, respectively. The minimal effects of substituents in the 3- and 6-positions of RLx−• on the magnetic coupling strength is understood through electronic structure calculations, which show negligible spin density on the substituents and associated C atoms of the ring. Finally, the radical-bridged complexes are single-molecule magnets, with relaxation barriers of Ueff = 50(1), 41(1), 38(1), and 33(1) cm−1 for R = OMe, Cl, NO2, and SMe2, respectively. Taken together, these results provide the first examination of how bridging ligand substitution influences magnetic coupling in semiquinoid-bridged compounds, and they establish design criteria for the synthesis of semiquinoid-based molecules and materials.

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