ORCID Profile
0000-0002-9365-370X
Current Organisation
The University of Edinburgh
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Publisher: Elsevier BV
Date: 2006
Publisher: American Chemical Society (ACS)
Date: 30-07-2002
DOI: 10.1021/JA026407G
Abstract: The reaction between 2-(hydroxyethyl)pyridine (hepH) and a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3](ClO4) and [Mn3O(O2CMe)6(py)3](py) in MeCN leads to isolation of [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 10% yield. The complex is 2MnII,16MnIII and consists of a Mn4O6 central unit to either side of which is attached a Mn7O9 unit. Magnetization data collected in the 2.0-4.0 K and 20-50 kG ranges were fit to yield S = 13, g = 1.86, and D = -0.13 cm-1 = -0.19 K, where D is the axial zero-field splitting parameter. AC susceptibility studies in the 0.04-4.0 K range at frequencies up to 996 Hz display out-of-phase (chiM' ') signals, indicative of a single-molecule magnet (SMM). Magnetization vs applied DC field scans exhibit hysteresis at <1.0 K, confirming 1 to be a SMM. DC magnetization decay data were collected on both a microcrystalline s le and a single crystal, and the combined data were used to construct an Arrhenius plot. Between 3.50 and 0.50 K, the relaxation rate is temperature-dependent with an effective barrier to relaxation (Ueff) of 14.8 cm-1 = 21.3 K. Below ca. 0.25 K, the relaxation rate is temperature-independent at 1.3 x 10-8 s-1, indicative of quantum tunneling of magnetization (QTM) between the lowest energy Ms = +/-13 levels of the S = 13 state. Complex 1 is both the largest spin and highest nuclearity SMM to exhibit QTM.
Publisher: Elsevier BV
Date: 03-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1CC13558A
Abstract: The use of derivatised salicylaldoximes in manganese chemistry has led to the synthesis of a family of approximately fifty hexanuclear ([Mn(III)(6)]) and thirty trinuclear ([Mn(III)(3)]) Single-Molecule Magnets (SMMs). Deliberate, targeted structural distortion of the metallic core afforded family members with increasingly puckered configurations, leading to a switch in the pairwise magnetic exchange from antiferromagnetic to ferromagnetic. Examination of both the structural and magnetic data revealed a semi-quantitative magneto-structural correlation, from which the factors governing the magnetic properties could be extracted and used for predicting the properties of new family members and even more complicated structures containing analogous building blocks. Herein we describe an overview of this extensive body of work and discuss its potential impact on similar systems.
Publisher: American Chemical Society (ACS)
Date: 25-09-2003
DOI: 10.1021/IC034654V
Abstract: The reaction of [NEt(4)](2)[Fe(2)OCl(6)] with sodium benzoate, 4,6-dimethyl-2-hydroxypyrimidine (dmhp), and 1,1,1-tris(hydroxymethyl)ethane (H(3)thme) gives the undecametallic compound [NEt(4)][Fe(11)O(4)(O(2)CPh)(10)(thme)(4)(dmhp)(2)Cl(4)]. X-ray crystallography, EPR spectroscopy, bulk magnetic susceptibility studies, and low-temperature single-crystal magnetic measurements were used to characterize the compound. Magnetic measurements indicate an S = (11)/(2) ground state with the parameters g = 2.03 and D = -0.46 cm(-)(1). Single-crystal magnetic studies show hysteresis of molecular origin at T < 1.2 K with fast quantum mechanical tunneling at zero field.
Publisher: Elsevier BV
Date: 07-2003
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA14811E
Abstract: We present the solvothermal synthesis, structural and magnetic characterisation of a family of Cr( iii ) cages and extended networks comprising {Cr( iii ) 3 O(O 2 CR 1 ) 3 (R 2 -sao)} 2− (R 1 = H, CH 3 , C(CH 3 ) 3 , C 14 H 9 R 2 = Me, Ph, t Bu, C 10 H 6 ) building blocks.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B802927J
Abstract: The use of pyridine-2-amidoxime in reaction with NiCl2.6H2O in the presence of NaOMe has led to a cationic NiII 12 cluster with novel structural features each cluster molecule is a ferromagnet with a spin ground state of S = 6 arising from ferromagnetic exchange between the six octahedral NiII ions, but with intercationic interactions also affecting the magnetic properties.
Publisher: American Chemical Society (ACS)
Date: 16-05-2007
DOI: 10.1021/IC070320K
Abstract: We report the synthesis, by solvothermal methods, of the tetradecametallic cluster complexes [M14(L)6O6(OMe)18Cl6] (M=FeIII, CrIII) and [V14(L)6O6(OMe)18Cl6-xOx] (L=anion of 1,2,3-triazole or derivative). Crystal structure data are reported for the {M14} complexes [Fe14(C2H2N3)6O6(OMe)18Cl6], [Cr14(bta)6O6(OMe)18Cl6] (btaH=benzotriazole), [V14O6(Me2bta)6(OMe)18Cl6-xOx] [Me2btaH=5,6-Me2-benzotriazole eight metal sites are VIII, the remainder are disordered between {VIII-Cl}2+ and {VIV=O}2+] and for the distorted [FeIII14O9(OH)(OMe)8(bta)7(MeOH)5(H2O)Cl8] structure that results from non-solvothermal synthetic methods, highlighting the importance of temperature regime in cluster synthesis. Magnetic studies reveal the {Fe14} complexes to have ground state electronic spins of S<or=25, among the highest known, while in contrast the {Cr14} complex has an S=0 ground state despite having a very similar structure and all complexes being dominated by intramolecular antiferromagnetic exchange interactions. The {Fe14} complexes undergo a magnetic phase transition to long-range ordering at relatively high temperatures for molecular species, which are governed by the steric bulk of the triazole (TN=1.8 and 3.4 K for L=bta- and H2C2N3-, respectively). The huge spins of the {Fe14} complexes lead to very large magnetocaloric effects (MCE)-the largest known for any material below 10 K-which is further enhanced by spin frustration within the molecules due to the competing antiferromagnetic interactions. The largest MCE is found for [Fe14(C2H2N3)6O6(OMe)18Cl6] with an isothermal magnetic entropy change -DeltaSm of 20.3 J kg-1 K-1 at 6 K for an applied magnetic field change of 0-7 T.
Publisher: Royal Society of Chemistry (RSC)
Date: 18-11-2002
DOI: 10.1039/B209445B
Abstract: The reaction of MnF3 with benzotriazole (BTAH) in hot MeOH gives the Mn(III) complex [Mn26O16(OH)10(OMe)6(F)10(BTA)20(BTAH)2(MeOH)13(H2O)] which displays hysteresis and temperature-independent magnetisation relaxation at low temperature.
Publisher: American Physical Society (APS)
Date: 17-10-2006
Publisher: American Physical Society (APS)
Date: 09-11-2007
Publisher: American Chemical Society (ACS)
Date: 03-07-2007
DOI: 10.1021/IC7006638
Abstract: Two unusual mixed-valent {MnIII6MnII} bitetrahedra display frustrated magnetic exchange, leading to S = 13/2 +/- 1 and 11/2 +/- 1 ground states and slow magnetization relaxation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8DT04229B
Abstract: A family of polymetallic cages are presented which includes a rare ferromagnetically coupled [Ni( ii ) 2 ] dimer.
Publisher: American Chemical Society (ACS)
Date: 04-12-2008
DOI: 10.1021/CG800947Z
Publisher: Elsevier BV
Date: 10-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B914538A
Publisher: American Chemical Society (ACS)
Date: 23-07-2008
DOI: 10.1021/JP802195X
Abstract: We study the magnetic properties of two new functionalized single-molecule magnets belonging to the Mn 6 family (general formula [Mn (III)6O2(R-sao)6(O2C-th)2L(4-6)], where R=H (1) or Et (2), HO2C-th=3-thiophene carboxylic acid, L=EtOH, H2O and saoH2 is salicylaldoxime) and their grafting on the Au(111) surface. Complex 1 exhibits spin ground-state S=4, as the result of ferromagnetic coupling between the two antiferromagnetic Mn (III) 3 triangles, while slight structural changes in complex 2, switch the dominant magnetic exchange interactions from anti- to ferromagnetic, enhancing the spin ground-state to S=12 and, consequently, the effective energy barrier for the relaxation of magnetization. Direct-current and alternating-current magnetic susceptibility measurements show that the functionalized complexes preserve the main magnetic properties of the corresponding not-functionalized Mn 6 clusters (i.e., total spin value and magnetic behavior as a function of temperature), though a reduction of the anisotropy barrier is observed in complex 2. For both complexes, the -O2C-th functionalization allows the direct grafting on Au(111) surface by liquid-phase deposition. X-ray photoemission spectroscopy demonstrates that the stoichiometry of the molecular cores is preserved after grafting. Scanning tunneling microscopy (STM) reveals a sub-monolayer distribution of isolated clusters with a slightly higher coverage for complex 1. The cluster stability in the STM images and the S-2p energy positions demonstrate, for both derivatives, the strength of the grafting with the gold surface.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B911820A
Abstract: The synthesis and characterisation of a large family of trimetallic [Mn(III)(3)] Single-Molecule Magnets is presented. The complexes reported can be ided into three categories with general formulae (type 1) [Mn(III)(3)O(R-sao)(3)(X)(sol)(3-4)] (where R = H, Me, (t)Bu X = (-)O(2)CR (R = H, Me, Ph etc) sol = py and/or H(2)O), (type 2) [Mn(III)(3)O(R-sao)(3)(X)(sol)(3-5)] (where R = Me, Et, Ph, (t)Bu X = (-)O(2)CR (R = H, Me, Ph etc) sol = MeOH, EtOH and/or H(2)O), and (type 3) [Mn(III)(3)O(R-sao)(3)(sol)(3)(XO(4))] (where R = H, Et, Ph, naphth sol = py, MeOH, beta-pic, Et-py, (t)Bu-py X = Cl, Re). We show that deliberate structural distortions of the molecule can be used to tune the observed magnetic properties. In the crystals the ferromagnetic triangles are involved in extensive inter-molecular H-bonding which is clearly manifested in the magnetic behaviour, producing exchange-biased SMMs. These interactions can be removed by ligand replacement to give "simpler" SMMs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B822305J
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B926704B
Abstract: We report the synthesis and magnetic characterisation of a series of planar [M₇] (M= Ni(II), Zn(II)) disc complexes [Ni₇(OH)₆(L₁)₆](NO₃)₂ (1), [Ni₇(OH)₆(L₁)₆](NO₃)₂·2MeOH (2), [Ni₇(OH)₆(L₁)₆](NO₃)₂·3MeNO₂ (3), [Ni₇(OH)₆(L₂)₆](NO₃)₂·2MeCN (4), [Zn₇(OH)₆(L₁)₆](NO₃)₂·2MeOH·H₂O (5) and [Zn₇(OH)₆(L₁)₆](NO₃)₂·3MeNO₂ (6) (where HL₁ = 2-iminomethyl-6-methoxy-phenol, HL₂ = 2-iminomethyl-4-bromo-6-methoxy-phenol). Each member exhibits a double-bowl pseudo metallocalix[6]arene topology whereby the in idual [M₇] units form molecular host cavities which are able to accommodate various guest molecules (MeCN, MeNO₂ and MeOH). Magnetic susceptibility measurements carried out on complexes 1 and 4 indicate weak exchange between the Ni(II) centres.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT02281F
Abstract: Conversion of dimer → linear tetramer → cyclic hexamer reveals remarkable topological size effects.
Publisher: American Chemical Society (ACS)
Date: 04-10-2003
DOI: 10.1021/IC034979B
Abstract: The reaction of MnF(3) with 5,6-dimethylbenzotriazole (Me(2)BTAH) gives the [Mn(III)(8)] complex [Mn(8)O(4)(OMe)(2)(Me(2)BTA)(6)F(8)(Me(2)BTAH)(MeOH)(8)] and the [Mn(IV)(3)Mn(III)(10)] complex [Mn(13)O(12)(Me(2)BTA)(12)F(6)(MeOH)(10)(H(2)O)(2)]. The octametallic species is an "intermediate" in the formation of the tridecametallic cluster.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3DT51131F
Abstract: The synthesis, structural and magnetic characterisation of a family of homo- and heterometallic complexes constructed with the Schiff base ligands 2-iminomethyl-6-methoxy-phenol (L1H) and 2-imino-6-methoxy-phenol (L2H), are discussed. Members include the heterometallic tetranuclear complexes of general formula [Na2M2(X)2(L1)4(Y)2] (where M = Fe(III), X = (-)OMe, Y = NO3(-) (1) and M = Ni(II), X = N3(-) and Y = MeCN (2)), each possessing a butterfly-like topology. We also report the formation of the heterometallic molecular cage [Na3Ni2(L1)6](ClO4) (3) whose metallic skeleton describes a [rare] trigonal bipyramid, the homometallic 1-D coordination polymer [Mn(L1)2(Cl)]n (4), and the tetranuclear cubane clusters [Mn(III)3Mn(IV)(O)3(OEt)(OAc)3(L1)3] (5) and [Ni4(μ3-OMe)4(L2)4(MeOH)4] (6). Dc and ac magnetic susceptibility studies on complexes 5 and 6 reveal S = 9/2 and S = 4 spin ground states.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B820362H
Abstract: The reaction of Mn(ClO4)(2).6H2O with Naphth-saoH2 (Naphth-saoH2=2-hydroxy-1-napthaldoxime) in pyridine (py) forms the complex [MnIII3O(Naphth-sao)3(py)3](ClO4).0.5py (.0.5py) in very good yields. Reaction of with NaO2CPh in EtOH produces the complex [MnIII6O2(Naphth-sao)6(O2CPh)2(EtOH)6].[MnIII6O2(Naphth-sao)6(O2CPh)2(EtOH)4].2.5Et2O.0.5H2O (.2.5Et2O.0.5H2O). Further reaction of complex with 1 equivalent of both NaN3 and Mn(ClO4)(2).6H2O in MeOH produces the complex [MnII2MnIII6O2(Naphth-sao)6(N3)6(MeOH)8].10MeOH (.10MeOH) that displays an S approximately 0 ground state. Ligand substitution of Naphth-saoH2 with Me-saoH2 in CH2Cl2-MeOH for the latter complex (Me-saoH2= 2-hydroxyphenylethanone oxime) forms the complex [MnII2MnIII6O2(Me-sao)6(N3)6(MeOH)8].10MeOH (.10MeOH) that displays an S=7 ground state with Ueff= 44.6 K. In all four complexes the main building block is the triangular {MnIII3O(R-sao)3} unit (R=Naphth for , and R=Me for ). The ligand substitution in triggers a structural distortion in the [Mn6] sub-core as observed by the increased (Mn-N-O-Mn) torsion angles in , switching the interactions from antiferro- to ferromagnetic, dramatically changing the ground-state of the octanuclear complexes from S=0 to 7.
Publisher: American Chemical Society (ACS)
Date: 05-11-2012
DOI: 10.1021/JA309211D
Abstract: A toroidal magnetic moment in the absence of conventional total magnetic moment is observed in a {Dy(6)} ring. The reason for the net toroidal arrangement of the local magnetic moments is the high symmetry of the complex in combination with strong intra-molecular dipolar interactions between Dy ions. The description of single-ion and inter-ion anisotropic magnetic interactions is achieved here for the first time fully ab initio, i.e., without use of phenomenological parameters.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1DT11118C
Abstract: The serendipitous self-assembly of the complex [Mn(III)(2)Zn(II)(2)(Ph-sao)(2)(Ph-saoH)(4)(hmp)(2)] (1),whose magnetic core consists solely of two symmetry equivalent Mn(iii) ions linked by two symmetry equivalent -N-O- moieties, provides a relatively simple model complex with which to study the magneto-structural relationship in oxime-bridged Mn(III) cluster compounds. Dc magnetic susceptibility measurements reveal ferromagnetic (J = +2.2 cm(-1)) exchange resulting in an S = 4 ground state. Magnetisation measurements performed at low temperatures and high fields reveal the presence of significant anisotropy, with ac measurements confirming slow relaxation of the magnetisation and Single-Molecule Magnetism behaviour. Simulations of high field, high frequency EPR data reveal a single ion anisotropy, D((Mn(III))) = -3.83 cm(-1). DFT studies on a simplified model complex of 1 reveal a pronounced dependence of the exchange coupling on the relative twisting of the oxime moiety with respect to the metal ion positions, as suggested previously in more complicated [Mn(III)(3)] and [Mn(III)(6)] clusters.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9DT01968E
Abstract: The magnetism, Mössbauer, and structural properties of a series of borate appended ligands are described.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B810835H
Abstract: The employment of di-2-pyridyl ketone, (py)2CO, in manganese(II) acetate chemistry is reported. The syntheses, crystal structures and magnetochemical characterisation are described for [MnII4(O2CMe)4{(py)2C(OH)O}4] () and [MnII10MnIII4O4(O2CMe)20{(py)2C(OH)O}4] (), where (py)2C(OH)O- is the monoanion of the gem-diol form of the ligand. The reaction of Mn(O2CMe)(2).4H2O with one equivalent of (py)2CO in Me2CO gives . Complex was obtained from the 1:1 reaction, in EtOH, between Mn(O2CMe)(2).4H2O and (py)2CO in the presence of NEt3. The tetranuclear molecule has a cubane topology with the MnII and the deprotonated oxygen atoms from the eta1:eta3:eta1:micro3 ligands occupying alternate vertices of the cube. The core of consists of two mixed valence cubane {MnII2MnIII2(micro3-O)2(micro3-OR'')2}4+ subunits that are linked through an unusual {MnII6(eta1:eta2:micro-O2CMe)6(eta2:eta2:micro3-O2CMe)2}4+ moiety via twelve eta1:eta1:micro MeCO2- groups. Some suggestions have been made concerning the possible assembly of from . The magnetic properties of in the 300-5 K range have been modelled with two J values, which reveal weak antiferromagnetic interactions within the molecule. Complex has a low spin ground state. This work demonstrates the flexibility, versatility and synthetic potential of combining (py)2CO with carboxylate ligands.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B811143J
Abstract: The synthesis and magnetic properties of three new members of a family of salicyaldoxime based [Mn6] single-molecule magnets possessing new structural types, core topologies and Mn oxidation state distributions are reported. The isostructural complexes [MnIII6O2(R-sao)6(X)2(EtOH)6] (R = Et, X = Br (1) R = Me, X = I (2)) exhibit single-molecule magnet behaviour with spin Hamiltonian parameters S = 12, g = 1.98 and D = -0.36 cm(-1) in both cases. The hexametallic cluster [MnIII4MnIV2O2(OMe)(4-)(Et-sao)6(MeOH)2].MeOH (3.MeOH) possesses a planar rod-like topology and a mixed valent [MnIV4MnIII2] core, which is unprecedented in this family of [Mn6] SMMs.
Publisher: American Chemical Society (ACS)
Date: 05-01-2005
DOI: 10.1021/IC048857A
Abstract: The reaction of 2-(hydroxyethyl)pyridine (hepH) with a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3]ClO4 and [Mn3O(O2CMe)6(py)3] in MeCN afforded the new mixed-valent (16Mn(III), 2Mn(II)), octadecanuclear complex [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 20% yield. Complex 1 crystallizes in the triclinic space group P. Direct current magnetic susceptibility studies in a 1.0 T field in the 5.0-300 K range, and variable-temperature variable-field dc magnetization studies in the 2.0-4.0 K and 2.0-5.0 T ranges were obtained on polycrystalline s les. Fitting of magnetization data established that complex 1 possesses a ground-state spin of S = 13 and D = -0.18 K. This was confirmed by the value of the in-phase ac magnetic susceptibility signal. Below 3 K, the complex exhibits a frequency-dependent drop in the in-phase signal, and a concomitant increase in the out-of-phase signal, consistent with slow magnetization relaxation on the ac time scale. This suggests the complex is a single-molecule magnet (SMM), and this was confirmed by hysteresis loops below 1 K in magnetization versus dc field sweeps on a single crystal. Alternating current and direct current magnetization data were combined to yield an Arrhenius plot from which was obtained the effective barrier (U(eff)) for magnetization reversal of 21.3 K. Below 0.2 K, the relaxation becomes temperature-independent, consistent with relaxation only by quantum tunneling of the magnetization (QTM) through the anisotropy barrier via the lowest-energy MS = +/-13 levels of the S = 13 spin manifold. Complex 1 is thus the SMM with the largest ground-state spin to display QTM.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2DT31995K
Abstract: The heterobimetallic complex [Cu(II)Mn(III)(L)(2)(py)(4)](ClO(4))·EtOH (1) built using the pro-ligand 2,2'-biphenol (LH(2)), contains a rare ex le of a Jahn-Teller compressed Mn(III) centre. Dc magnetic susceptibility measurements on 1 reveal a strong antiferromagnetic exchange between the Cu(II) and Mn(III) ions mediated through the phenolate O-atoms (J = -33.4 cm(-1)), with magnetisation measurements at low temperatures and high fields suggesting significant anisotropy. Simulations of high-field and high frequency powder EPR data suggest a single-ion anisotropy D(Mn(III)) = +4.45 cm(-1). DFT calculations also yield an antiferromagnetic exchange for 1, though the magnitude is overestimated (J(DFT) = -71 cm(-1)). Calculations reveal that the antiferromagnetic interaction essentially stems from the Mn(d(x(2)-y(2)))-Cu(d(x(2)-y(2))) interaction. The computed single-ion anisotropy and cluster anisotropy also correlates well with experiment. A larger cluster anisotropy for the S = 3/2 state compared to the single-ion anisotropy of Mn(III) is rationalised on the basis of orbital mixing and various contributions that arise due to the spin-orbit interaction.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CE25047K
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT12229D
Abstract: A family of homo-valent [Co(II)(7)(OH)(6)(L(1))(6)](NO(3))(2) (1), [(MeOH)(2) is a subset of Co(II)(7)(OH)(6)(L(1))(6)](NO(3))(2) (2) (where L(1)H = 2-iminomethyl-6-methoxyphenol) and hetero-valent [(NO(3))(2) is a subset of Co(III)Co(II)(6)(OH)(6)(L(2))(6)](NO(3))·3MeCN (4) (where L(2)H = 2-iminophenyl-6-methoxyphenol) complexes possess metallic skeletons describing planar hexagonal discs. Their organic exteriors form double-bowl shaped topologies, and coupled with their 3-D connectivity, this results in the formation of molecular cavities in the solid state. These confined spaces are shown to behave as host units in the solid state for guests including solvent molecules and charge balancing counter anions. Magnetic susceptibility measurements on 2 and 4 reveal weak ferro- and ferrimagnetism, respectively. The utilisation of other Co(II) salt precursors gives rise to entirely different species including the mononuclear and trinuclear complexes [Co(II)(L(2))(2)] (5) and [Co(III)(2)Na(I)(1)(L(3))(6)](BF(4)) (6) (where L(3)H = 2-iminomethyl-4-bromo-6-methoxyphenol).
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5DT01463H
Abstract: Sheet Metal: The deliberate in situ Schiff base condensation of two organic subunits (hydroxamic acid and phenolic aldehyde) leads to polydentate ligands capable of forming large Cu( ii ) cages of nuclearities ranging from [Cu 10 ] to [Cu 30 ].
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7SC04460G
Abstract: The synergistic combination of high pressure techniques with ab initio methods creates a powerful tool to understand giant magnetic anisotropy.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9DT01531K
Abstract: A family of mono- and ditopic hydroxamic acids has been employed in the synthesis of discrete (0D) and (1- and 2-D) extended network coordination complexes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B712188A
Abstract: Reaction of MnCl(2).4H(2)O with H(3)L (H(3)L = tris(6-hydroxymethyl-2-pyridylmethyl)amine) in methanol gives hepta-coordinated [Mn(H(3)L)]Cl(2) involving attachment of Mn(II) to all four nitrogens and three hydroxymethyl arms. Reaction of H(3)L with Fe(ClO(4))(2).6H(2)O in CH(3)CN in the presence of NaO(2)CC(6)H(5) in an attempt to make [Fe(III)OH(H(3)L)(O(2)CC(6)H(5))](ClO(4)), a putative model for soybean lipoxygenase-1, instead gave rise to the linear triiron(III) complex [Fe(3)L(2)](ClO(4))(3) with all three hydroxymethyl arms deprotonated and forming three alkoxide bridges between each Fe(III) centre. The central Fe(III) is hexa-coordinated to only the alkoxide bridges and flanked by two hepta-coordinated iron(III) centres analogous to the Mn(ii) complex. [Fe(3)L(2)](ClO(4))(3) exhibits two reversible 1e(-) reductions to mixed-valence [Fe(3)L(2)](2+) and [Fe(3)L(2)](+) forms. Structure data and magnetochemistry on [Fe(3)L(2)](ClO(4))(3) reveals the tightest Fe-O-Fe angle (87.4 degrees ) and shortest Fe...Fe distance (2.834 A) yet found for any weakly antiferromagnetically-coupled high spin alkoxide-bridged di- or triiron(iii) system and challenges current theories involved in correlating the extent/nature of magnetic interactions in such systems based on Fe-O(bridge) distances and Fe-O-Fe angles. The central hexa-alkoxide coordinated Fe(III) is novel and shows a remarkable resistance towards reduction to Fe(II).
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT04233G
Abstract: Bis-calix[4]arene is a highly versatile ligand that is capable of forming a range of polymetallic clusters. Use of an N , O -chelating co-ligand affords a very high nuclearity mixed-valence Mn cluster (shown here) that displays coordination modes relative to each ligand type.
Publisher: Wiley
Date: 13-08-2003
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B900743A
Abstract: Use of the dicarboxylates iso-phthalate and succinate in the preparation of [Mn(6)] SMMs links the hexametallic units into 1D chains.
Publisher: Wiley
Date: 09-07-2008
Publisher: Wiley
Date: 10-10-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2DT01477G
Abstract: An [Fe III 8 ] hexagonal bipyramid displays antiferromagnetic exchange between the two capping tetrahedral ions and the six ring octahedral ions resulting in a spin ground state, S = 10.
Publisher: American Physical Society (APS)
Date: 10-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1SC00038A
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 06-2007
Publisher: Elsevier BV
Date: 09-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B717534E
Abstract: The synthesis and magnetic properties of the compounds [HNEt(3)][Fe(2)(OMe)(Ph-sao)(2) (Ph-saoH)(2)].5MeOH (1.5MeOH), [Fe(3)O(Et-sao)(O(2)CPh)(5)(MeOH)(2)].3MeOH (2.3MeOH), [Fe(4)(Me-sao)(4)(Me-saoH)(4)] (3), [HNEt(3)](2)[Fe(6)O(2)(Me-sao)(4)(SO(4))(2)(OMe)(4)(MeOH)(2)] (4), [Fe(8)O(3)(Me-sao)(3)(tea)(teaH)(3)(O(2)CMe)(3)] (5), [Fe(8)O(3)(Et-sao)(3)(tea)(teaH)(3)(O(2)CMe)(3)] (6), and [Fe(8)O(3)(Ph-sao)(3)(tea)(teaH)(3)(O(2)CMe)(3)] (7) are reported (Me-saoH(2) is 2'-hydroxyacetophenone oxime, Et-saoH(2) is 2'-hydroxypropiophenone oxime and Ph-saoH(2) is 2-hydroxybenzophenone oxime). 1-7 are the first Fe(III) compounds synthesised using the derivatised salicylaldoxime ligands, R-saoH(2). 1 is prepared by treatment of Fe(2)(SO(4))(3).6H(2)O with Ph-saoH(2) in the presence of NEt(3) in MeOH 2 prepared by treatment of Fe(ClO(4))(2).6H(2)O with Et-saoH(2) and NaO(2)CPh in the presence of NEt(4)OH in MeOH 3 prepared by treatment of Fe(ClO(4))(2).6H(2)O with Me-saoH(2) and NaO(2)CCMe(3) in the presence of NEt(4)OH in MeOH and 4 prepared by treatment of Fe(2)(SO(4))(3).6H(2)O with Me-saoH(2) in the presence of NEt(3) in MeOH. 4 is a rare ex le of a polynuclear iron complex containing a coordinated SO(4)(2-) ion. Compounds 5-7 are prepared by treatment of Fe(O(2)CMe)(2) with Me-saoH(2) (5), Et-saoH(2) (6), Ph-saoH(2) (7) in the presence of H(3)tea (triethanolamine) in MeOH, and represent the largest nuclearity Fe(III) clusters containing salicyladoxime-based ligands, joining a surprisingly small family of characterised octanuclear Fe complexes. Variable temperature magnetic susceptibilty measurements of 1, 3 and 5-7 reveal all five complexes possess S = 0 spin ground states 2 possesses an S = 1/2 spin ground state, while 4 has an S = 4 +/- 1 spin ground state.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B924143D
Abstract: The syntheses, structures and magnetic properties of nine new iron complexes containing salicylaldoxime (saoH(2)) or derivatised salicylaldoximes (R-saoH(2)), [Fe(3)O(OMe)(Ph-sao)(2)Cl(2)(py)(3)].2MeOH (1.2MeOH), [Fe(3)O(OMe)(Ph-sao)(2)Br(2)(py)(3)].Et(2)O (2.Et(2)O), [Fe(4)(Ph-sao)(4)F(4)(py)(4)].1.5MeOH (3.1.5MeOH), [Fe(6)O(2)(OH)(2)(Et-sao)(2)(Et-saoH)(2)(O(2)CPh)(6)] (4), [HNEt(3)](2)[Fe(6)O(2)(OH)(2)(Et-sao)(4)(O(2)CPh(Me)(2))(6)].2MeCN (5.2MeCN), [Fe(6)O(2)(O(2)CPh)(10)(3-(t)But-5-NO(2)-sao)(2)(H(2)O)(2)].2MeCN (6.2MeCN), [Fe(6)O(2)(O(2)CCH(2)Ph)(10)(3-(t)But-sao)(2)(H(2)O)(2)].5MeCN (7.5MeCN), {[Fe(6)Na(3)O(OH)(4)(Me-sao)(6)(OMe)(3)(H(2)O)(3)(MeOH)(6)].MeOH}n (8.MeOH) and [HNEt(3)](2)[Fe(12)Na(4)O(2)(OH)(8)(sao)(12)(OMe)(6)(MeOH)(10)] (9) are discussed. The predominant building block appears to be the triangular [Fe(3)O(R-sao)(3)](+) species which can self-assemble into more elaborate arrays depending on reaction conditions. An interesting observation is that the R-saoH(-)/R-sao(2-) ligand system tends to adopt coordination modes similar to carboxylates. The most unusual molecule is the [Fe(4)F(4)] molecular square, 3. While Cl(-) and Br(-) appear to act only as terminal ligands, the F(-) ions bridge making a telling impact on molecular structure and topology.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7SC00487G
Abstract: A family of [MIII2MII3] n+ trigonal bipyramidal cages are characterised in the solution and solid state.
Publisher: Wiley
Date: 10-11-2009
Abstract: A family of planar disc-like hexa-, octa- and decametallic Ni(II) complexes exhibit dominant ferromagnetic exchange. The deca- and octametallic clusters [Ni(II) (10)(tmp)(2)(N(3))(8)(acac)(6)(MeOH)(6)] (1, H(3)tmp=1,1,1-tris(hydroxymethyl)propane acac=acetylacetonate) and [Ni(II) (8)(thme)(2)(O(2)CPh)(4)(Cl)(6)(MeCN)(6)(H(2)O)(2)] (2, H(3)thme=1,1,1-tris(hydroxymethyl)ethane) represent rare ex les of Ni(II)-based single-molecule magnets, and [Ni(II) (10)] (1) possesses the largest barrier to magnetisation reversal of any Ni(II) single-molecule magnet to date.
Publisher: American Chemical Society (ACS)
Date: 19-11-2014
DOI: 10.1021/IC5023467
Abstract: The syntheses, structures, and magnetic properties of two heterometallic Cu(II)-Ln(III) (Ln(III) = Gd, Tb, and Dy) families, utilizing triethanolamine and carboxylate ligands, are reported. The first structural motif displays a nonanuclear {Cu(II)2Ln(III)7} metallic core, while the second reveals a hexadecanuclear {Cu(II)4Ln(III)12} core. The differing nuclearities of the two families stem from the choice of carboxylic acid used in the synthesis. Magnetic studies show that the most impressive features are displayed by the {Cu(II)2Gd(III)7} and {Cu(II)4Gd(III)12} complexes, which display a large magnetocaloric effect, with entropy changes -ΔSm = 34.6 and 33.0 J kg(-1) K(-1) at T = 2.7 and 2.9 K, respectively, for a 9 T applied field change. It is also found that the {Cu(II)4Dy(III)12} complex displays single-molecule magnet behavior, with an anisotropy barrier to magnetization reversal of 10.1 K.
Publisher: Wiley
Date: 07-10-2004
Abstract: The syntheses, structures and magnetic properties of three new MnIII clusters, [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1), [Mn(0O6(OH)2(bta)8(py)8F8] (2) and [NHEt3]2[Mn3O(bta)6F3] (3), are reported (bta=anion of benzotriazole), thereby demonstrating the utility of MnF3 as a new synthon in Mn cluster chemistry. The "melt" reaction (100 degrees C) between MnF(3) and benzotriazole (btaH, C6H5N3) under an inert atmosphere, followed by dissolution in MeOH produces the cluster [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1) after two weeks. Complex 1 crystallizes in the triclinic space group P1, and consists of a complicated array of metal tetrahedra linked by mu3-O2- ions, mu3- and mu2-OH- ions, mu2-MeO- ions and mu2-bta- ligands. The "simpler" reaction between MnF3 and btaH in boiling MeOH (50 degrees C) also produces complex 1. If this reaction is repeated in the presence of pyridine, the decametallic complex [Mn10O6(OH)2(bta)8(py)8F8] (2) is produced. Complex 2 crystallizes in the triclinic space group P1 and consists of a "supertetrahedral" [Mn(III)10] core bridged by six mu3-O2- ions, two mu3-OH- ions, four mu2-F- ions and eight mu2-bta- ions. The replacement of pyridine by triethylamine in the same reaction scheme produces the trimetallic species [NHEt3]2[Mn3O(bta)6F3] (3). Complex 3 crystallises in the monoclinic space group P2(1)/c and has a structure analogous to that of the basic metal carboxylates of general formula [M3O(RCO2)6L3]0/+, which consists of an oxo-centred metal triangle with mu2-bta- ligands bridging each edge of the triangle and the fluoride ions acting as the terminal ligands. DC magnetic susceptibility measurements in the 300-1.8 K and 0.1-7 T ranges were investigated for all three complexes. For each, the value of chi(M)T decreases with decreasing temperatures this indicates the presence of dominant antiferromagnetic exchange interactions in 1-3. For complex 1, the low-temperature value of chi(M)T is 10 cm(3) K mol(-1) and fitting of the magnetisation data gives S=4, g=2.0 and D=-0.90 cm(-1). For complex 2, the value of chi(M)T falls to a value of approximately 5.0 cm(3) K mol(-1) at 1.8 K, which is consistent with a small spin ground state. For the triangular complex 3, the best fit to the experimental chi(M)T versus T data was obtained for the following parameters: Ja = -5.01 cm(-1), Jb = +9.16 cm(-1) and g=2.00, resulting in an S=2 spin ground state. DFT calculations on 3, however, suggest an S=1 or S=0 ground state with J(a)=-2.95 cm(-1) and J(b)=-2.12 cm(-1). AC susceptibility measurements performed on 1 in the 1.8-4.00 K range show the presence of out-of-phase AC susceptibility signals, but no peaks. Low-temperature single-crystal studies performed on 1 on an array of micro-SQUIDS show the time- and temperature-dependent hysteresis loops indicative of single-molecule magnetism behaviour.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CE40859K
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0DT01593H
Abstract: The syntheses, structures and magnetic properties of six iron complexes stabilised with the derivatised salicylaldoxime ligands Me-saoH(2) (2-hydroxyethanone oxime) and Et-saoH(2) (2-hydroxypropiophenone oxime) are discussed. The four hexanuclear and two octanuclear complexes of formulae [Fe(8)O(2)(OMe)(4)(Me-sao)(6)Br(4)(py)(4)]·2Et(2)O·MeOH (1·2Et(2)O·MeOH), [Fe(8)O(2)(OMe)(3.85)(N(3))(4.15)(Me-sao)(6)(py)(2)] (2), [Fe(6)O(2)(O(2)CPh-4-NO(2))(4)(Me-sao)(2)(OMe)(4)Cl(2)(py)(2)] (3), [Fe(6)O(2)(O(2)CPh-4-NO(2))(4)(Et-sao)(2)(OMe)(4)Cl(2)(py)(2)]·2Et(2)O·MeOH (4·2Et(2)O·MeOH), [HNEt(3)](2)[Fe(6)O(2)(Me-sao)(4)(SO(4))(2)(OMe)(4)(MeOH)(2)] (5) and [HNEt(3)](2)[Fe(6)O(2)(Et-sao)(4)(SO(4))(2)(OMe)(4)(MeOH)(2)] (6) all are built from a series of edge-sharing [Fe(4)(μ(4)-O)](10+) tetrahedra. Complexes 1 and 2 display a new μ(4)-coordination mode of the oxime ligand and join a small group of Fe-phenolic oxime complexes with nuclearity greater than six.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C002247K
Abstract: Nickel and cobalt seamed metal-organic capsules have been isolated and studied using structural, magnetic and computational approaches. Antiferromagnetic exchange in the Ni capsule results from coordination environments enforced by the capsule framework.
Publisher: Elsevier BV
Date: 11-2005
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B811796A
Abstract: Replacement of carboxylate and solvent with facially capping tripodal ligands enhances the single-molecule magnet (SMM) properties of [Mn(III)3] triangles.
Publisher: World Scientific Pub Co Pte Lt
Date: 30-11-2004
DOI: 10.1142/S0217979204027591
Abstract: High frequency EPR investigations have been undertaken to gain insight into the spin environment of a novel pentanuclear Fe III cluster, [ Fe 5 O 2 ( OMe ) 2 ( Bta ) 4 ( BtaH )/( MeOH ) 5 Cl 5 ] ( Fe5Bta ). The elongated, centered ferric tetrahedron contains five Fe III ions with a S =15/2 ground spin state. Variable temperature EPR suggests that the first paramagnetic excited spin state is low lying. Employing high frequencies and fields in the EPR experiments allows for resolution of g anisotropy of the Fe III centers. We therefore are able to determine the g value of the Fe III ion precisely.
Publisher: Wiley
Date: 29-03-2012
Abstract: The synthesis and magnetic characterisation of a series of bis-μ-alkoxide bridged Mn(III) dinuclear complexes of general formula [Mn(III)(2)(μ-OR)(2)(biphen)(2)(ROH)(x)(L)(y)] (where R = Me, Et H(2) biphen = 2,2'-biphenol and L = terminally bonded N-donor ligand) is described, doubling the literature basis set for this type of complex. Building on these findings we have categorised all known μ-OR bridged Mn(III) dinuclear complexes into one of three classifications with respect to their molecular structures. We have then employed DFT and MO calculations to assess all potential magneto-structural correlations for this class of compound in order to identify the structural requirements for constructing ferromagnetic family members. Our analysis indicates that the most influential parameter which governs the exchange interaction in this class of compounds is the relative orientation of the JT axes of the Mn(III) atoms. A perpendicular orientation of the JT axes leads to a large ferromagnetic contribution to the exchange. These results also suggest that a large ferromagnetic interaction and a large anisotropy are unlikely to co-exist in such structural types.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT00752C
Abstract: Coordination compounds of the type [M II (L˙) 2 ][Re IV X 6 ] display a variety of different intra- and inter-molecular magnetic interactions.
Publisher: American Chemical Society (ACS)
Date: 10-06-2006
DOI: 10.1021/IC0607843
Abstract: The microwave-assisted reaction of Fe(O2CMe)2 with salicylaldoxime (saoH2) in pyridine produces an octametallic cluster in crystalline form in 2 min. The core describes a cube encapsulated in a tetrahedron, while sao2- exhibits a novel coordination mode.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT30674C
Abstract: The dimeric complex [Mn(III)(2)(Naphth-sao)(2)(Naphth-saoH)(2)(MeOH)(2)]·4MeOH (1·4MeOH), acts as a simple model complex with which to examine the magneto-structural relationship in polymetallic, oxime-bridged Mn(III) complexes. Dc magnetic susceptibility studies reveal that ferromagnetic exchange is mediated through the heavily twisted Mn-O-N-Mn moiety (J = +1.24 cm(-1)) with magnetisation measurements at low temperatures and high fields suggesting significant anisotropy. Simulations of high field, high frequency EPR data reveal a single ion anisotropy, D((Mn(III))) = -3.94 cm(-1). Theoretical studies on simplified model complexes of 1 reveal that calculated values of the exchange coupling and the anisotropy are in excellent agreement with experiment, with the weak ferromagnetism resulting from an accidental orthogonality between the Mn-N-O plane of the first Mn(III) ion and the Jahn-Teller axis of the second Mn(III) ion.
Publisher: American Chemical Society (ACS)
Date: 21-07-2004
DOI: 10.1021/IC049547V
Abstract: The reaction of the trimetallic species [Fe(3)O(PhCOO)(6)(H(2)O)(3)]NO(3) with 1,1,1-tris(hydroxymethyl)ethane (H(3)thme) affords either the octametallic species [Fe(8)(PhCOO)(12)(thme)(4)] 1 or the hexadecametallic species [Fe(16)(EtO)(4)(PhCOO)(16)(Hthme)(12)](NO(3))(4) 2, depending on the nature of the solvent used for crystallization. The structure of 1 can be described as a nonplanar wheel of eight Fe(III) ions bridged by a combination of PhCOO(-) and thme(3)(-) ligands, and 2 as a nonplanar wheel of sixteen Fe(III) ions bridged by PhCOO(-), Hthme(2)(-), and EtO(-) ligands. Both compounds can be broken down into simple units of two metal ions and the bridging ligands that connect them. The best fits of the chi vs T curves in the 300-10 K temperature range were obtained with the parameters g = 2.0, J(1) = -24.0 cm(-1), and J(2) = -8.59 cm(-1) for [Fe(8)] and g = 2.0, J(1) = -25.0 cm(-1), J(2) = -11.73 cm(-1), and J(3) = -69.3 cm(-1) for [Fe(16)]. Density functional theory (DFT) calculations show that the antiferromagnetic interactions between the metals in the dinuclear units decrease when two types of bridging ligands are present, as expected for an orbital counter-complementarity effect.
Publisher: American Physical Society (APS)
Date: 02-06-2008
Publisher: Elsevier BV
Date: 06-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA06064D
Abstract: We present a structural, magnetic and theoretical analysis on a family of Ni( ii ) cages which include 12-MC Ni(ii) -4 [Ni 5 ] metallacrowns. Subtle changes to reaction conditions aid the assembly of larger [Ni 7 ] and [Ni 9 ] architectures, depending on the hydroxamic acid used.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B804897E
Abstract: We report the synthesis of a series of mixed valence Mn(II/IV) tetranuclear clusters [Mn(II)2Mn(IV)2O2(heed)2(EtOH)6Br2]Br2 (1), [Mn(II)2Mn(IV)2O2(heed)2(H2O)2Cl4].2EtOH.H2O (2.2EtOH.H2O), [Mn(II)2Mn(IV)2O2(heed)2(heedH2)2](ClO4)4 (3), [Mn(II)2Mn(IV)2O2(heed)2(MeCN)2(H2O)2(bpy)2](ClO4)4 (4) and [Mn(II)2Mn(IV)2O2(heed)2(bpy)2Br4].2MeOH (5.2MeOH). Clusters 1-5 are constructed from the tripodal ligand N,N-bis(2-hydroxyethyl)ethylene diamine (heedH2) and represent rare ex les of tetranuclear Mn clusters possessing the linear trans zig-zag topology, being the first Mn(II/IV) mixed-valent clusters of this type. The molecular clusters can then be used as building blocks in tandem with the (linear) linker dicyanamide ([N(CN)2]-, dca-) for the formation of a novel extended network {[Mn(II)2Mn(IV)2O2(heed)2(H2O)2(MeOH)2(dca)2]Br2}n (6), which exhibits a rare form of the 2D herring bone topology.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B916153H
Abstract: We report on a tetranuclear Mn(ii) complex possessing a F-bridged molecular square topology directed by 1,10-phenanthroline ligands.
Publisher: American Chemical Society (ACS)
Date: 15-03-2002
DOI: 10.1021/JA012403K
Abstract: The reaction of (NBu(n)(4))[Mn(8)O(6)Cl(6)(O(2)CPh)(7)(H(2)O)(2)] (1) with 2-(hydroxymethyl)pyridine (hmpH) or 2-(hydroxyethyl)pyridine (hepH) gives the Mn(II)(2)Mn(III)(10) title compounds [Mn(12)O(8)Cl(4)(O(2)CPh)(8)(hmp)(6)] (2) and [Mn(12)O(8)Cl(4)(O(2)CPh)(8)(hep)(6)] (3), respectively, with X = Cl. Subsequent reaction of 3 with HBr affords the Br(-) analogue [Mn(12)O(8)Br(4)(O(2)CPh)(8)(hep)(6)] (4). Complexes 2.2Et(2)O.4CH(2)Cl(2), 3.7CH(2)Cl(2), and 4.2Et(2)O.1.4CH(2)Cl(2) crystallize in the triclinic space group P1, monoclinic space group C2/c, and tetragonal space group I4(1)/a, respectively. Complexes 2 and 3 represent a new structural type, possessing isomeric [Mn(III)(10)Mn(II)(2)O(16)Cl(2)] cores but with differing peripheral ligation. Complex 4 is essentially isostructural with 3. A magnetochemical investigation of complex 2 reveals an S = 6 or 7 ground state and frequency-dependent out-of-phase signals in ac susceptibility studies that establish it as a new class of single-molecule magnet. These signals occur at temperatures higher than those observed for all previously reported single-molecule magnets that are not derived from [Mn(12)O(12)(O(2)CR)(16)(H(2)O)(x)]. A detailed investigation of forms of complex 2 with different solvation levels reveals that the magnetic properties of 2 are extremely sensitive to the latter, emphasizing the importance to the single-molecule magnet properties of interstitial solvent molecules in the s les. In contrast, complexes 3 and 4 are low-spin molecules with an S = 0 ground state.
Publisher: American Physical Society (APS)
Date: 09-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC03229H
Abstract: In situ high-pressure single-crystal diffraction and spectroscopic techniques have been used to study a previously unreported Cu-framework bis[1-(4-pyridyl)butane-1,3-dione]copper( ii ) (CuPyr-I).
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B822235E
Abstract: The synthesis and characterisation of a large family of hexametallic [Mn(III)(6)] Single-Molecule Magnets of general formula [Mn(III)(6)O(2)(R-sao)(6)(X)(2)(sol)(4-6)] (where R = H, Me, Et X = (-)O(2)CR' (R' = H, Me, Ph etc) or Hal(-) sol = EtOH, MeOH and/or H(2)O) are presented. We show how deliberate structural distortions of the [Mn(3)O] trinuclear moieties within the [Mn(6)] complexes are used to tune their magnetic properties. These findings highlight a qualitative magneto-structural correlation whereby the type (anti- or ferromagnetic) of each Mn(2) pairwise magnetic exchange is dominated by the magnitude of each in idual Mn-N-O-Mn torsion angle. The observation of magneto-structural correlations on such large polymetallic complexes is rare and represents one of the largest studies of this kind.
Publisher: Elsevier BV
Date: 02-2008
Publisher: Informa UK Limited
Date: 02-2018
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Euan Brechin.