About the calculation of exchange coupling constants in polynuclear transition metal complexes

Ruiz, Eliseo; Rodríguez‐Fortea, Antonio; Cano, Joan; Álvarez, Santiago; Alemany, Pere

doi:10.1002/jcc.10257

Cited by 489 publications

(372 citation statements)

References 38 publications

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“…The J values were obtained as previously proposed. [47] X-ray crystallographic data for 2 (see Table 1 . Data were collected on an orange plate (0.30 0.25 0.02 mm 3 ) using a Nonius Kappa CCD diffractometer with graphite-monochromated Mo Ka radiation (T = 150 K, l = 0.71073 ).…”

Section: Resultsmentioning

confidence: 99%

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

Barrios

Aguilà

Roubeau

et al. 2009

Chemistry A European J

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The ligand 1,3-bis[3-oxo-3-(2-hydroxyphenyl)propionyl]benzene (H(4)L), designed to align transition metals into tetranuclear linear molecules, reacts with M(II) salts (M=Ni, Co, Cu) to yield complexes with the expected [MMMM] topology. The novel complexes [Co(4)L(2)(py)(6)] (2; py=pyridine) and [Na(py)(2)][Cu(4)L(2)(py)(4)](ClO(4)) (3) have been crystallographically characterised. The metal sites in complexes 2 and 3, together with previously characterised [Ni(4)L(2)(py)(6)] (1), favour different coordination geometries. These have been exploited for the deliberate synthesis of the heterometallic complex [Cu(2)Ni(2)L(2)(py)(6)] (4). Complexes 1, 2, 3 and 4 exhibit antiferromagnetic interactions between pairs of metals within each cluster, leading to S=0 spin ground states, except for the latter cluster, which features two quasi-independent S=1/2 moieties within the molecule. Complex 4 gathers the structural and physical conditions, thus allowing it to be considered as prototype of a two-qbit quantum gate.

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Section: Resultsmentioning

confidence: 99%

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

Barrios

Aguilà

Roubeau

et al. 2009

Chemistry A European J

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“…The DFT calculations were performed using Noodleman's broken symmetry (BS) approach (29) to compute J values, using Gaussian 09 software (30) with the hybrid B3LYP functional (31)(32)(33). We used a triple zeta valence (34) basis set on Cr and split valence polarization for the rest of the elements (35).…”

Section: Methodsmentioning

confidence: 99%

A classification of spin frustration in molecular magnets from a physical study of large odd-numbered-metal, odd electron rings

Baker

Timco

Piligkos

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

130

103

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The term "frustration" in the context of magnetism was originally used by P. W. Anderson and quickly adopted for application to the description of spin glasses and later to very special lattice types, such as the kagomé. The original use of the term was to describe systems with competing antiferromagnetic interactions and is important in current condensed matter physics in areas such as the description of emergent magnetic monopoles in spin ice. Within molecular magnetism, at least two very different definitions of frustration are used. Here we report the synthesis and characterization of unusual ninemetal rings, using magnetic measurements and inelastic neutron scattering, supported by density functional theory calculations. These compounds show different electronic/magnetic structures caused by frustration, and the findings lead us to propose a classification for frustration within molecular magnets that encompasses and clarifies all previous definitions. ,4,7-triazacyclononane). One area where molecular magnetism might contribute is in spin frustration (3), which is important in condensed matter physics in areas such as spin ice (4) and spin liquids (5). Potential model systems would be odd-numbered metal rings where the metal array forms equilateral triangles, or regular pentagons, heptagons, and larger 2D rings. Alternatively 3D solids made from regular odd-numbered rings should also be frustrated, e.g., regular tetrahedra and octahedra contain triangular faces and regular icosahedra contain pentagonal faces.Studies of spin frustration in molecular systems are largely restricted to that of triangular trimetallic species (6, 7). There are a few reports of five-metal rings but no detailed magnetic studies of such compounds (8), with the exception of a {Cu 5 } cage (9). The only significant examples of larger frustrated molecules are studies of the {M 30 } Keplerates (10) and a recent report of a heptametallic {VO} 7 ring (11), where the studies are limited to low temperature magnetization. There is also a report of an {Fe 9 } complex that can, very approximately, be described as a nine-metal ring (12).A further difficulty is that precisely what is meant by frustration varies in this area. The strictest definition used in molecular magnetism, from Kahn (13), states that frustration must result in a spin degenerate ground state, typically a degenerate pair of S = 1/2 states. Surprisingly, this definition excludes all possible models built from integer spins, as in such cases (for example a regular pentagon of s = 1 spins), the ground total spin state is unique and has S = 0. This definition thus seems prohibitively strict. At the other extreme, the term frustration has been used to describe cases where there are competing antiferromagnetic interactions, even where those interactions result in a unique spin ground state that can be described using a classical picture, with spins represented as arrows pointing alternately up and down. This definition seems, if anything, too permissive.We have reported studies of...

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“…The "melt" reaction (100 8C) between MnF 3 and benzotriazole (btaH, C 6 H 5 N 3 ) under an inert atmosphere, followed by dissolution in MeOH produces the cluster [Mn 26 O 17 (OH) 8 (OMe) 4 F 10 -(bta) 22 (MeOH) 14 (H 2 O) 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 m 3 -O 2À ions, m 3 -and m 2 -OH À ions, m 2 -MeO À ions and m 2 -bta À ligands.…”

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confidence: 99%

New Routes to Polymetallic Clusters: Fluoride‐Based Tri‐, Deca‐, and Hexaicosametallic Mn^III Clusters and their Magnetic Properties

Jones

Rajaraman

Brockman

et al. 2004

Chemistry A European J

109

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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.

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About the calculation of exchange coupling constants in polynuclear transition metal complexes

Cited by 489 publications

References 38 publications

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

A classification of spin frustration in molecular magnets from a physical study of large odd-numbered-metal, odd electron rings

New Routes to Polymetallic Clusters: Fluoride‐Based Tri‐, Deca‐, and Hexaicosametallic Mn^III Clusters and their Magnetic Properties

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About the calculation of exchange coupling constants in polynuclear transition metal complexes

Cited by 489 publications

References 38 publications

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

A classification of spin frustration in molecular magnets from a physical study of large odd-numbered-metal, odd electron rings

New Routes to Polymetallic Clusters: Fluoride‐Based Tri‐, Deca‐, and Hexaicosametallic MnIII Clusters and their Magnetic Properties

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New Routes to Polymetallic Clusters: Fluoride‐Based Tri‐, Deca‐, and Hexaicosametallic Mn^III Clusters and their Magnetic Properties