Structure and Magnetic Studies on a Series of Two-Dimensional Iron(II) Framework Materials with Varying Ligand Characteristics

2017 ◽  
Vol 70 (5) ◽  
pp. 623 ◽  
Author(s):  
Matthew A. D. Roxburgh ◽  
Samantha Zaiter ◽  
Xina I. B. Hudson ◽  
Benjamin R. Mullaney ◽  
John E. Clements ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Large Family ◽  
Structural Motif ◽  
Magnetic Studies ◽  
Bridging Ligands ◽  
Coordination Environment ◽  
Pyridyl Ligands ◽  
Framework Materials ◽  
Grid Topology ◽  
Varying Length

Targeting the general (4,4)-grid structural motif, we have prepared seven new coordination polymers in the general family [Fe(NCX)2(L)2]·(guest) (L = bis-pyridyl-type bridging ligands; X = S, Se) as an extension of the well-established spin crossover framework (SCOF) family. In all cases, the (4,4)-grid topology is formed by the bridging of octahedral iron(ii) sites in the equatorial plane by bis-pyridyl ligands of varying length, flexibility, and intermolecular interaction capacity. In particular, the six ligands n-(4-pyridyl)-isonicotinamide (pin), trans-1,2-bis(4′-pyridyl)ethane (tvp), 1,2-dibromo-1,2-bis(4′-pyridyl)ethane (dbbpe), bis(4-pyridyl)-1,2,4,5-tetrazine (bptz), 4,4′-bis(pyridyl)acetylene (bpac), and 1,4-bis(4-pyridylethynyl)benzene (bpeben) have been utilised. The seven new materials [Fe(NCS)2(pin)2]·2(MeCN) (pin-S), [Fe(tvp)2(NCS)2]·1/2(tvp)·(CH3CH2OH) (tvp-S), [Fe(dbbpe)2(NCS)2]·6(CH3CN) (dbbpe-S), [Fe(NCS)2(bptz)2]·2(CHCl3)·6(EtOH) (bptz-S), [Fe(NCSe)2(bptz)2]·4(CHCl3)·(EtOH)·(H2O) (bptz-Se), [Fe(NCS)2(bpac)2]·2(PrOH) (bpac-S), and [Fe(NCS)2(bpeben)2]·2(CHCl3) (bpeben-S) all form (4,4)-grids of varying size that are arranged in a parallel stacked topology. Despite being in the [FeN6] coordination environment known to be conducive to spin crossover, these materials all remain high-spin with thermal variation. These results are discussed in context with the large family of SCOFs that show varied spin crossover behaviours.

Exchange-Biasing in a Dinuclear Dysprosium(III) Single-Molecule Magnet with a Large Energy Barrier for Magnetization Reversal

2019 ◽  
Author(s):  
Tian Han ◽  
Marcus J. Giansiracusa ◽  
Zi-Han Li ◽  
You-Song Ding ◽  
Nicholas F. Chilton ◽  
...  
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Energy Barrier ◽  
Magnetic Hysteresis ◽  
Large Energy ◽  
Magnetic Studies ◽  
Bridging Ligands ◽  
Single Molecule Magnet ◽  
Exchange Biasing

A dichlorido-bridged dinuclear dysprosium(III) single-molecule magnet [Dy<sub>2</sub>L<sub>2</sub>(<i>µ</i>-Cl)<sub>2</sub>(THF)<sub>2</sub>] has been made using a diamine-bis(phenolate) ligand, H<sub>2</sub>L. Magnetic studies show an energy barrier for magnetization reversal (<i>U</i><sub>eff</sub>) around 1000 K. Exchange-biasing effect is clearly seen in magnetic hysteresis with steps up to 4 K. <i>Ab</i> initio calculations exclude the possibility of pure dipolar origin of this effect leading to the conclusion that super-exchange <i>via</i> the chloride bridging ligands is important.

scholarly journals Solvent-Induced Hysteresis Loop in Anionic Spin Crossover (SCO) Isomorph Complexes

2021 ◽  
Vol 7 (6) ◽  
pp. 75
Author(s):  
Emmelyne Cuza ◽  
Samia Benmansour ◽  
Nathalie Cosquer ◽  
Françoise Conan ◽  
Carlos J. Gómez-García ◽  
...  
Keyword(s):  
Metal Ion ◽  
Spin Crossover ◽  
Magnetic Behaviour ◽  
Magnetic Studies ◽  
Tridentate Ligands ◽  
Tripodal Ligand ◽  
Single Crystal Structures ◽  
One Step ◽  
Lower Temperature ◽  
Step Transition

Reaction of Fe(II) with the tris-(pyridin-2-yl)ethoxymethane (py3C-OEt) tripodal ligand in the presence of the pseudohalide ancillary NCSe- (E = S, Se, BH3) ligand leads to the mononuclear complex [Fe(py3C-OEt)2][Fe(py3C-OEt)(NCSe)3]2·2CH3CN (3), which has been characterised as an isomorph of the two previously reported complexes, Fe(py3C-OEt)2][Fe(py3C-OEt)(NCE)3]2·2CH3CN, with E = S (1), BH3 (2). X-ray powder diffraction of the three complexes (1–3), associated with the previously reported single crystal structures of 1–2, revealed a monomeric isomorph structure for 3, formed by the spin crossover (SCO) anionic [Fe(py3C-OEt)(NCSe)3]− complex, associated with the low spin (LS) [Fe(py3C-OEt)2]2+ cationic complex and two solvent acetonitrile molecules. In the [Fe(py3C-OEt)2]2+ complex, the metal ion environment involves two py3C-OEt tridentate ligands, while the [Fe(py3C-OEt)(NCSe)3]− anion displays a hexacoordinated environment involving three N-donor atoms of one py3C-OEt ligand and three nitrogen atoms arising from the three (NCSe)− coligands. The magnetic studies for 3 performed in the temperature range 300-5-400 K, indicated the presence of a two-step SCO transition centred around 170 and 298 K, while when the sample was heated at 400 K until its complete desolvation, the magnetic behaviour of the high temperature transition (T1/2 = 298 K) shifted to a lower temperature until the two-step behaviour merged with a gradual one-step transition at ca. 216 K.

Observation of the First Spin Crossover in an Iron(II) Complex with an S 6 Coordination Environment: Tris[bis( N , N ‐diethylamino)carbeniumdithiocarboxylato]iron(II) Hexafluorophosphate

2018 ◽  
Vol 24 (68) ◽  
pp. 17955-17963
Author(s):  
Tomoaki Sugaya ◽  
Takashi Fujihara ◽  
Takashi Naka ◽  
Takao Furubayashi ◽  
Akiyuki Matsushita ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Coordination Environment

New Ternary Phosphide La7Pd17P12: Preparation and Crystal Structure

2002 ◽  
Vol 57 (12) ◽  
pp. 1409-1413 ◽  
Author(s):  
S. Budnyk ◽  
Yu. Prots ◽  
Yu. Kuz’ma ◽  
Yu. Grin
Keyword(s):  
Crystal Structure ◽  
Temperature Region ◽  
Large Family ◽  
Structural Features ◽  
Structural Motif ◽  
Crystal Data ◽  
Monoclinic Structure ◽  
X Ray ◽  
Data Space ◽  
Metal Ratio

The title compound was prepared from elements by sintering in the temperature region between 1073 and 1473 K. The monoclinic structure of La7Pd17P12 was solved and refined from X-ray single crystal data: space group C2/m, a = 24.519(1), b = 4.0859(5), c = 13.6106(8)Å , β = 112.129(3)°, Z = 2, RF = 0.025 for 1065 unique of 4877 measured reflections and 112 refined parameters. Main structural motif of the new phosphide are condensed blocks of trigonal prisms around phosphorus atoms connected to infinite chains via lanthanum atoms. The structural features of La7Pd17P12 are discussed in comparison with some representatives of a large family of structures with metal / non-metal ratio close to 2 : 1.

An Investigation of Photo- and Pressure-Induced Effects in a Pair of Isostructural Two-Dimensional Spin-Crossover Framework Materials

2014 ◽  
Vol 20 (24) ◽  
pp. 7448-7457 ◽  
Author(s):  
Natasha F. Sciortino ◽  
Suzanne M. Neville ◽  
Cédric Desplanches ◽  
Jean-François Létard ◽  
Victor Martinez ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Two Dimensional ◽  
Framework Materials

scholarly journals Spin Cross-Over (SCO) Complex Based on Unsymmetrical Functionalized Triazacyclononane Ligand: Structural Characterization and Magnetic Properties

2019 ◽  
Vol 5 (1) ◽  
pp. 19 ◽  
Author(s):  
Merzouk Halit ◽  
Mélissa Roger ◽  
Véronique Patinec ◽  
Said Yefsah ◽  
Carlos Gómez-García ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Nmr Spectroscopy ◽  
Functional Groups ◽  
Structural Characterization ◽  
Spin Crossover ◽  
Magnetic Studies ◽  
Dsc Measurements ◽  
Hexadentate Ligand

The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring that is functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1), which was characterized as the first Fe(II) complex based on the unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As observed in the few parent examples that are based on the symmetrical N-functionalized tacn ligands, the triazacyclononane ring is facially coordinated and the N-donor atoms of the three functional groups (two pyridine and one aniline groups) are disposed in the same side of the tacn ring, leading to a distorted FeN6 environment. The magnetic studies of 1 revealed the presence of an incomplete spin crossover (SCO) transition above 425 K, whose progress would be prevented by a very exothermic thermal decomposition at ca. 472 K, as shown by thermogravimetric and DSC measurements.

Thermal- and Light-Induced Spin Crossover in Novel 2D Fe(II) Metalorganic Frameworks {Fe(4-PhPy)2[MII(CN)x]y}·sH2O: Spectroscopic, Structural, and Magnetic Studies

2009 ◽  
Vol 48 (13) ◽  
pp. 6130-6141 ◽  
Author(s):  
M. Seredyuk ◽  
A. B. Gaspar ◽  
V. Ksenofontov ◽  
M. Verdaguer ◽  
F. Villain ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Magnetic Studies ◽  
Metalorganic Frameworks

Long range antiferromagnetic exchange in dinuclear copper(II) complexes containing 1,4-dicyanamidobenzene dianion bridging ligands

1995 ◽  
Vol 73 (4) ◽  
pp. 573-580 ◽  
Author(s):  
Linnus L. Cheruiyot ◽  
Robert J. Crutchley ◽  
Laurence K. Thompson ◽  
J.E. Greedan ◽  
Guo Liu
Keyword(s):  
Magnetic Susceptibility ◽  
Elemental Analysis ◽  
Epr Spectroscopy ◽  
Antiferromagnetic Exchange ◽  
Temperature Dependent ◽  
Magnetic Studies ◽  
Bridging Ligands ◽  
Dimer Model ◽  
Bridging Ligand ◽  
Exchange Constants

Six Cu(II)dimers, [{Cu(dien)}2(μ-dicyd)][CF3SO3]2 (1), [{Cu(dien)}2(μ-Me2dicyd)][CF3SO3]2 (2), [{Cu(dien)}2(μ-Cl2dicyd)][CF3SO3]2 (3), [{Cu(L)}2(μ-dicyd)] (4), [{Cu(L)}2(μ-Me2dicyd)] (5), and [{Cu(L)}2(μ-Cl2dicyd)] (6), where dicyd2−, Me2dicyd2− and Cl2dicyd2− are unsubstituted, 2,5-dimethyl- and 2,5-dichloro-1,4-dicyanamidobenzene dianions, respectively, dien is diethylenetriamine, and L− = 1,3-bis(2-pyridylimino)isoindolinato, have been synthesized and characterized by elemental analysis, IR, UV–vis, and EPR spectroscopy, and magnetic studies. Temperature-dependent magnetic susceptibility measurements of the complexes 1–6 from 5 to 300 K are reported. The data for 2, 3, 5, and 6 have been fitted to a dimer model with a modified Bleaney–Bowers expression which derived antiferromagnetic exchange constants −J = 10.6, 4.5, 5.2, and 3.0 cm−1, respectively (where the Hamiltonian is of the form [Formula: see text]) For 4, an approach to a maximum in χm with decreasing temperature gave an estimated −J < 3.5 cm−1. Only complex 1 showed Curie–Weiss behavior. This is far weaker antiferromagnetic exchange compared to that observed for dinuclear Ru(III) complexes incorporating the dicyd2− bridging ligands (J. Am. Chem Soc. 114, 5130 (1992)) and is attributed to a symmetry and energy mismatch between Cu(II) σ* magnetic orbitals and the πnb molecular orbitals of the bridging ligand which are important for superexchange. Keywords: superexchange, copper dimer, dicyanamidobenzene.

Magnetic Exchange Effects in {CrIII2DyIII2} Single Molecule Magnets Containing Alcoholamine Ligands

2014 ◽  
Vol 67 (11) ◽  
pp. 1581 ◽  
Author(s):  
Stuart K. Langley ◽  
Daniel P. Wielechowski ◽  
Boujemaa Moubaraki ◽  
Brendan F. Abrahams ◽  
Keith S. Murray
Keyword(s):  
Single Molecule ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Studies ◽  
Single Molecule Magnets ◽  
Magnetic Exchange ◽  
Bridging Ligands ◽  
Metallic Core ◽  
Ligand Coordination ◽  
Magnetic Hysteresis Loops

The synthesis and magnetic characterisation of four new heterometallic {CrIII2DyIII2} complexes 2–5 are described. The present work follows on from a recently isolated complex [CrIII2DyIII2(OMe)2(O2CPh)4(mdea)2(NO3)2] (1) (mdeaH2 = N-methyldiethanolamine), which displayed impressive single molecule magnet (SMM) properties, notably highly coercive magnetic hysteresis loops below 3.5 K. Compounds 1–5 all display a planar butterfly type metallic core arrangement, with the DyIII ions occupying the central body positions and the CrIII ion the outer wing positions. The core is stabilized by the amine–diolate, and carboxylate bridging ligands. Variation of the amine–diolate ligand resulted in several structural analogues which maintain the same metallic core, but differ from the parent 1 in the outer ligand coordination environment. Magnetic studies reveal complexes 2–5 also display SMM behaviour, unambiguously confirmed via low temperature magnetic hysteresis loops, each displaying wide coercive fields, a rare occurrence for lanthanoid-based SMMs.

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