The novel mixed-valence, exchange-coupled, class III dimer [L2Fe2(µ-OH)3]2+(L =N,N′,N″-trimethyl-1,4,7-triazacyclononane)

Drüeke, S.; Chaudhuri, Phalguni; Pohl, Klaus; Wieghardt, Karl; Ding, X.‐Q.; Bill, Eckhard; Sawaryn, A.; Trautwein, Alfred X.; Winkler, H.; Gurman, S. J.

doi:10.1039/c39890000059

Cited by 84 publications

(55 citation statements)

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“…A dinuclear ironA C H T U N G T R E N N U N G (III) complex is known which contain three m-hydroxo groups, for example, [Fe 2 A C H T U N G T R E N N U N G (m-OH) 3 A C H T U N G T R E N N U N G (Me 3 tacn) 2 ]; [24] whether mononuclear fragments related to this dimer can be generated and then used in place of phosphonates in 1 is debatable, but it seems a worthy synthetic target as we strive to achieve an icosahedron.…”

Section: Discussionmentioning

confidence: 99%

Studies of an Fe₉ Tridiminished Icosahedron

Tolis

Engelhardt

Mason

et al. 2006

Chemistry A European J

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The synthesis and structural characterization of a nonanuclear FeIII cage complex is reported. The nine iron centers in [Fe9(mu3-O)4(O3PPh)3(O2CCMe3)13] lie on the vertices of an incomplete icosahedron, with the P atoms of triphenylphosphonate at the other three vertices. The paramagnetic core therefore describes a tridiminished icosahedron. Magnetic studies suggest an S=1/2 ground state for the molecule. Analysis of exchange paths and the susceptibility data point to the interpretation that the cluster can be divided into two nearly decoupled sections: an {Fe6O3} section, with an S=0 ground state, in which three oxo-centered triangles bound a central triangle that is not oxo-centered; and an {Fe3O} triangle with S=1/2. The analysis of the susceptibility data leads to a Heisenberg model based on three significant antiferromagnetic exchange interactions, with values of 173.7 cm-1 in the {Fe3O} triangle, and 30.9 and 19.1 cm-1 within the {Fe6O3} section, while the exchange between them is <1 cm-1. With these assignments, the theoretical low-temperature differential susceptibility is also in very good agreement with measurements up to 50 T. Magnetic measurements in the milli-kelvin range reveal striking hysteresis loops and magnetization reversals associated with a Landau-Zener-Stückelberg (LZS) transition as enhanced by the occurrence of a phonon bottleneck.

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Section: Discussionmentioning

confidence: 99%

Studies of an Fe₉ Tridiminished Icosahedron

Tolis

Engelhardt

Mason

et al. 2006

Chemistry A European J

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“…Only a few examples of similarly coordinated diiron complexes are known, which either lack a neutral bridging ligand, such as dimeric bis(acetylacetonato)iron(II) [14], and/or contain iron (III). Two examples of the latter type of complex are the tris(μ-hydroxo)-bridged mixed-valent species, [Fe 2 (OH) 3 (tmtacn) 2 ] 2+ (tmtacn = N,N′,N″-trimethyltriazacyclononane) [15], and ferric citrate [16].…”

Section: Resultsmentioning

confidence: 99%

Unexpected assembly of a novel triply bridged diiron(II) core by a bidentate Schiff base ligand

Smith

Day

Que

et al. 2007

Inorganica Chimica Acta

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The unusual dinucleating properties of a simple bidentate Schiff base (LH, 1) in the presence of weakly coordinating methanol solvent lead to the self-assembly of [Fe II 2 (2) (b and t refer to bridging and terminally bound ligands, respectively). Complex 2 is the first diiron (II) species in which the two metal centers are triply bridged by single atoms in an asymmetric fashion, involving both μ-O Ph and μ-OH Me bridges. This binding mode produces an Fe···Fe distance of 3.139 (1) Å. Dinucleation appears to be driven by a combination of ligand deficiency and solvent-mediated chemistry reminiscent of host-guest interactions. The presence of a μ-MeOH ligand is unprecedented in iron chemistry. Parallel-mode EPR spectra of complex 2 recorded at 4 K show an intense negative signal at g || ≈ 16, suggesting the dimeric form exists in solution.

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“…These values, and that of 110 for the bipyrimidine-bridged complex [(bipy) 2 Fe(l-bipym)Fe(bipy) 2 ] 5+ [47], are significantly higher than the value of 4 corresponding to zero net stabilisation of the mixed valence species, but are very much less than the values of the order of 10 8 which are the highest values reached before Class II (in the Robin and Day classification [48]) mixed valence species merge into fully delocalised Class III species. [(LLL)Fe(l-OH) 3-Fe(LLL)] 2+ (where LLL ¼ N,N¢,N¢¢-trimethyl-1,4,7-triazacyclononane) [49] is, on electronic and Mo¨ssbauer spectroscopic evidence, a Class III species with essentially complete electron delocalisation over the two iron centres. The FeÁ Á ÁFe distance in this last complex is only 2.50 Å (from EXAFS measurements)/2.51 Å (by X-ray diffraction), in [Fe 2 ((6)) 3 ] 4+ this distance is as much as 7.65 Å -there is a rough correlation between FeÁ Á ÁFe distance, the degree of metal-metal interaction, and stabilisation of the mixed valence species.…”

Section: Oxidationmentioning

confidence: 99%

Solvation and reactivity of a helical binuclear iron(II) complex with a tetradentate Schiff-base ligand

Blundell

Burgess

Hubbard

2005

Transition Met Chem

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Reaction of 2-acetylpyridine, hydrazine, and an iron(II) salt gives a low-spin binuclear iron(II) complex, [Fe 2 (pmk) 3 ] 4+ , in which three tetradentate Schiff base ligands span the two metal centres to give a complex of helical geometry. We report solubilities of the iodide and perchlorate salts, in H 2 O, in aqueous MeOH, and in aqueous DMSO (perchlorate only), up to 60% by vol of organic cosolvent. Transfer chemical potentials for the complex cation from H 2 O into the respective mixed solvents have been derived from these solubilities, to give a picture of solvation of this complex in the media studied. Kinetics of base hydrolysis of [Fe 2 (pmk) 3 ] 4+ have been established, in H 2 O and in 40% MeOH, 20 and 40% i-PrOH, and 20 and 40% DMSO, at 298.2 K. The reactivity of [Fe 2 (pmk) 3 ] 4+ is discussed in relation to reactivities of a selection of iron(II)-diimine complexes, ranging from [Fe(bipy) 3 ] 2+ and [Fe(phen) 3 ] 2+ to ligand-encapsulated cage complexes.

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The novel mixed-valence, exchange-coupled, class III dimer [L₂Fe₂(µ-OH)₃]²⁺(L =N,N′,N″-trimethyl-1,4,7-triazacyclononane)

Cited by 84 publications

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Studies of an Fe₉ Tridiminished Icosahedron

Studies of an Fe₉ Tridiminished Icosahedron

Unexpected assembly of a novel triply bridged diiron(II) core by a bidentate Schiff base ligand

Solvation and reactivity of a helical binuclear iron(II) complex with a tetradentate Schiff-base ligand

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The novel mixed-valence, exchange-coupled, class III dimer [L2Fe2(µ-OH)3]2+(L =N,N′,N″-trimethyl-1,4,7-triazacyclononane)

Cited by 84 publications

References 0 publications

Studies of an Fe9 Tridiminished Icosahedron

Studies of an Fe9 Tridiminished Icosahedron

Unexpected assembly of a novel triply bridged diiron(II) core by a bidentate Schiff base ligand

Solvation and reactivity of a helical binuclear iron(II) complex with a tetradentate Schiff-base ligand

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About

The novel mixed-valence, exchange-coupled, class III dimer [L₂Fe₂(µ-OH)₃]²⁺(L =N,N′,N″-trimethyl-1,4,7-triazacyclononane)

Studies of an Fe₉ Tridiminished Icosahedron

Studies of an Fe₉ Tridiminished Icosahedron