Synthesis and structure of [Fe(OMe)2(O2CCH2Cl)]10: a molecular ferric wheel

Taft, Kingsley L.; Lippard, Stephen J.

doi:10.1021/ja00182a027

Cited by 155 publications

(89 citation statements)

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“…5), the systems to be discussed below, were synthesized at the Institut für Organische Chemie in Erlangen [109] and labeled as substances 4 and 3 in the latter publication. There exist a large family of ferric wheels with a different even number ( 6 8 10 12 18 N = , , , , ) of iron atoms [109][110][111][112][113][114][115][116][117][118][119]. Besides the ferric ones, there have been reports on wheels with other transition metal ions such as an eight membered Cr(III) wheel [120], a Cu(II) [121,122], a Co(II) [123], a Mn(II) [124] and a 24 membered Ni(II) wheel [125].…”

Section: Ferric Wheelsmentioning

confidence: 99%

Density functional studies of molecular magnets

Postnikov

Kortus

Pederson

2006

Physica Status Solidi (b)

110

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PACS 71.15.Mb, 75.50.XxAfter a general introduction into the field of molecular magnets the discussion focuses on a more specific description of their most important representative species, single-molecule magnets incorporating transition metal ions. We overview traditional model approaches for the phenomenological description of such systems and outline some ways used to parameterize the corresponding models from experiment and from first-principle calculations. The latter can be either multi-determinantal quantum chemical schemes or those based on the density functional theory. In particular we discuss Heisenberg exchange parameters and magnetic anisotropy constants. As a practical example, an introduction into problems and properties of some single-molecule magnets which gained much attention within last years, namely Mn 12 -acetate, "Fe 8 " and "V 15 " systems, is given. This introduction into systems is followed by a critical comparison of calculation schemes based on the density functional theory that are particularly well suited for the study of molecular magnets. For the above systems we select some benchmark results, obtained by different methods. Finally, we outline our recent progress in the study of other single-molecule magnets, including sixmembered "ferric wheels", "ferric stars" and "Ni 4 " molecules, which we studied with the use of firstprinciples methods SIESTA and NRLMOL.

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Section: Ferric Wheelsmentioning

confidence: 99%

Density functional studies of molecular magnets

Postnikov

Kortus

Pederson

2006

Physica Status Solidi (b)

110

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“…[14] An eight- membered Fe II wheel of sulfide cubes, [{(Cy 3 P)FeS} 2 Fe 2 S 2 ] 4 has been prepared, [15] but all remaining iron wheels are based on octahedral Fe III . [16][17][18][19][20][21] What is the aggregation state if only one ligand can bridge? The treatment of 4 b with one equivalent of LiCCSitBu 3 per mole of Fe (chosen in part for size compatibility) afforded the ferrous cube [{(tBu 3 SiCC)Fe(m-SSitBu 3 )} 4 (C 6 H 6 ) 3 ] (6 (67 %)).…”

Section: àmentioning

confidence: 99%

“…[11,22] The cube is nearly perfect (Figure 3), with S-Fe-S av = 90.6 (8)8 and Fe-S-Fe av = 89.4 (8)8. Thiolate-containing cubes with a ferrous-only core are rarely observed, [15][16][17][18][19][20][21]23] although a ferrous acetylide phosphaneimide derivative is known. [24] The magnetic properties of 4 a, 4 b, 5 and 6 were briefly examined.…”

Section: àmentioning

confidence: 99%

“…Thiolate acetylide cube 6 was fit to a tetrahedral array of iron(ii) centers according to the Kambe method, [26] and it exhibited no significant interactions (0.5, 2.0 T; J = 0.1, 0.3 cm À1 ; m eff (295 K) = 5.7, 5.4 m B ). Most wheels based on octahedral Fe III motifs have modest antiferromagnetic behavior, [16][17][18][19][20][21] although certain Mn III (O h ), [27] Cr III (O h ), [28] and Ni II [29] wheels have manifested ferromagnetic properties.…”

Section: àmentioning

confidence: 99%

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Ferrous Wheels, Ellipse [(tBu₃SiS)FeX]_n, and Cube [(tBu₃SiS)Fe(CCSitBu₃)]₄

2003

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The controlled aggregation of low-coordinate, transitionmetal complexes can lead to the generation of unusual oligomers, polymers or clusters. Inspired by Hoffmann's treatise on tetrahedral units as building blocks, [1,2] we sought "XMY" species as potential monomers for [M(m-X)(m-Y)] n , an oligomer or polymer based on the edge-connectivity of tetrahedra. Literature precedent [3] suggested the use of bulky thiolate and halide ligands as the m-X and m-Y linkages. [5,6] hence desymmetrization was viewed as one means toward oligomerization. FeX 2 (thf) 2 and one equivalent of tBu 3 SiSNa(thf) x (x = 1.4-1.7) were stirred for 18-24 h to provide yellow [(X 2 Fe)(m-SSitBu 3 ) 2 {FeX(thf)}]Na(thf) 4 (2 a, X = Cl, 74 %; 2 b, X= Br, 86 %) and cis-[{I(thf)Fe} 2 -(m-SSitBu 3 ) 2 ] (3, 75 %) upon isolation. The structures of 1, 2 b and 3 were determined by single-crystal X-ray crystallography, and quenching studies (D 2 O/DCl in D 3 COD) suggested that 2 a has the same thiolate:THF ratio (1:3.9) as 2 b. Elemental analyses were indeterminate, probably because of variable desolvation. Each complex has a m eff consistent with an S = 2 ground state (Evans' method [7] in [D 8 ]THF) and little orbital contribution: 2 a, 4.8 m B ; 2 b, 4.5 m B ; 3, 4.8 m B .If the solvent (THF) was removed after the above procedures, and the remaining solids were heated under vacuum (2 a, 808C, 1.5 h; 2 b, 798C, 2 h); 3, 117 8C, 5 h) and extracted into benzene, then desolvation and aggregation occurred, but not to the expected polymers. Instead, ferrous wheels [Fe(m-X)(m-SSitBu 3 )] n (C 6 H 6 ) m (X = Cl, n = 12, 4 a, 45 %;[8] X = Br, n = 12, 4 b, 72%) [9] and the ferrous ellipse [Fe(m-I)(m-SSitBu 3 )] 14 (C 6 H 6 ) m (5, 16%) [10] were isolated by crystallization. The structures of these complexes were determined by single-crystal X-ray crystallography, [11] but the benzene molecules of solvation, determined from quenching studies to be~0.5-1.0 equivalent per Fe atom, exhibited significant disorder, and were removed from the refinement by using PLATON methods.The chloride ferrous wheel, 4 a (Figure 1), packs in a tetragonal array of columns; the bromide derivative, 4 b, is isomorphous. The wheels consist of edge-shared tetrahedra, with the inner diameter comprises m-X ligands, and the periphery composed of m-SSitBu 3 linkages. The orientation of each shared tetrahedral edge alternates relative to the ring plane such that the three different transannular X···X separations are basically the same (4 a, 9.484 (29) av; 4 b, 9.483 (22) av) Because of the greater size of Br ion, the iron atoms in 4 b are slightly displaced towards the outside of the wheel relative to 4 a.The iodide ellipse, 5 (Figure 2) is constructed of tetrahedra linked on the perimeter by m-SSitBu 3 ligands, and internally by bridging iodides. Ellipse 5 also packs in columnar fashion, and has transannular d(I···I) of 11.101 (2), 11.499 (2), 12.402 (2) and 13.469 (2) . The tetrahedra form a ring with the iodides inside, despite the d(FeI) av = 2.672 (11) that is substantially long...

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“…The literature on polymetallic compounds with cyclic metal cores has certain unusual gaps.S ince the publication in 1990 of both {Fe 10 } [1] by Lippard and Taft and {Cr 8 } [2] by Timco and co-workers,awide range of sizes have been reported for homometallic rings,i ncluding {Fe 18 }/{Ga 18 } [3] rings (currently the largest reported regular wheels,that is,where every edge and every vertex is chemically equivalent) to the more complex {Mn 32 }d ouble decker structure. [4] "Magic number" rings of {Mn 84 } [5] and {Pd 84 } [6] have also been reported.…”

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confidence: 99%

[CrF(O₂C^tBu)₂]₉: Synthesis and Characterization of a Regular Homometallic Ring with an Odd Number of Metal Centers and Electrons

et al. 2016

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The first regular homometallic ring containing an odd number of metal centers is reported. The ring was synthesized by means of amine-templated self-assembly. Extensive physical characterization studies,including magnetic measurements,p owder inelastic neutron scattering (INS), and DFT calculations,s how that the molecule has an ear perfect matchtothe expected behavior for afrustrated system with the lowest energy pair of S = 1/2 spin states separated by only 0.1 meV (0.8 cm À1).The literature on polymetallic compounds with cyclic metal cores has certain unusual gaps.S ince the publication in 1990 of both {Fe 10 } [1] by Lippard and Taft and {Cr 8 } [2] by Timco and co-workers,awide range of sizes have been reported for homometallic rings,i ncluding {Fe 18 }/{Ga 18 } [3] rings (currently the largest reported regular wheels,that is,where every edge and every vertex is chemically equivalent) to the more complex {Mn 32 }d ouble decker structure.[4] "Magic number" rings of {Mn 84 } [5] and {Pd 84 } [6] have also been reported. The largest cyclic metal structures remain the extraordinary molybdate wheels from Müller and co-workers.[7] However, rings with odd numbers of metal centers (termed herein oddnumbered rings), particularly those larger than triangles,a re conspicuous by their near absence.There are afew reported heterometallic nine-metal rings, including {Cr 7 V 2 }a nd a{ Cr 8 M} family.[8] However,r egular homometallic rings containing odd numbers of metal centers are restricted to metal triangles,asmall number of pentagons, [9,10] and as ingle heptametallic {V 7 }ring made by Oshio and co-workers with the vanadium sites bridged by ac yclodextrin ligand. [11] Large regular odd-numbered rings would show interesting physics associated with spin frustration, [12,13] which occurs when the classical magnetic energy cannot be simultaneously minimized for all individual two-spin interaction terms. Theoretical studies to classify the degree of frustration in such systems have been recently reported. [14] In 2002 the structures of two toroidal thiolate-bridged nickel structures, {Ni 9 }and {Ni 11 }, were published by Dahl and co-workers,both of which showed considerable geometric irregularity;h owever,n oc haracterization beyond crystallography was reported.[15] In 2004, Mezei et al. reported an onametallic copper ring {Cu 9 }that was not isolated but co-crystallized with arange of other copper rings. [16] We previously reported two nonametallic rings {Cr 9 F 10 } and {Cr 9 F 11 }( see below), each of which contained one edge with adefect breaking the regularity of the ring.[17] Herein, we report the synthesis of the first regular nine-metal homometallic ring, [CrF(O 2 C t Bu) 2 ] 9 1,a long with characterization of the ring by magnetometry and inelastic neutron scattering (INS) to explore the extent of spin frustration.Thes ynthesis of 1 is based on ap rocedure we previously developed for synthesizing hexametallic and heptametallic chromium horseshoes [18] -addition of at emplating amine to ar eaction that...

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Synthesis and structure of [Fe(OMe)2(O2CCH2Cl)]10: a molecular ferric wheel

Cited by 155 publications

References 0 publications

Density functional studies of molecular magnets

Density functional studies of molecular magnets

Ferrous Wheels, Ellipse [(tBu₃SiS)FeX]_n, and Cube [(tBu₃SiS)Fe(CCSitBu₃)]₄

[CrF(O₂C^tBu)₂]₉: Synthesis and Characterization of a Regular Homometallic Ring with an Odd Number of Metal Centers and Electrons

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Synthesis and structure of [Fe(OMe)2(O2CCH2Cl)]10: a molecular ferric wheel

Cited by 155 publications

References 0 publications

Density functional studies of molecular magnets

Density functional studies of molecular magnets

Ferrous Wheels, Ellipse [(tBu3SiS)FeX]n, and Cube [(tBu3SiS)Fe(CCSitBu3)]4

[CrF(O2CtBu)2]9: Synthesis and Characterization of a Regular Homometallic Ring with an Odd Number of Metal Centers and Electrons

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Ferrous Wheels, Ellipse [(tBu₃SiS)FeX]_n, and Cube [(tBu₃SiS)Fe(CCSitBu₃)]₄

[CrF(O₂C^tBu)₂]₉: Synthesis and Characterization of a Regular Homometallic Ring with an Odd Number of Metal Centers and Electrons