Deuteron NMR study of lattice dynamics affecting the rate of intramolecular electron transfer in the iron acetato oxo pyridine mixed-valence complex [Fe3O(O2CCH3)6(py)3](py)

Woehler, S. E.; Wittebort, Richard J.; Oh, Seung M.; Kambara, Takeshi; Hendrickson, David N.; Inniss, Daryl; Strouse, Charles E.

doi:10.1021/ja00238a014

Cited by 79 publications

(42 citation statements)

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“…There is an onset of solvate molecule motion in the crystal which occurs cooperatively in the valence-detrapping phase transition. This has been well documented in several solid-state 2H NMR studies of the solvate molecule motion [28,[30][31][32][33].…”

Section: Sample History Dependence and Pol Ymorphsmentioning

confidence: 75%

Electron Transfer in Mixed-Valence Complexes in the Solid State

Hendrickson

1991

Mixed Valency Systems: Applications in Chemistry, Physics and Biology

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ABSTRACT. The factors influencing the rate of intramolecular electron transfer (ET) in the solid state have been investigated for mixed-valence oxo-bridged trinuclear metal acetate complexes and salts of biferrocenium cations. Mixed-valence complexes which have potential-energy barriers for ET and are trapped on the vibrational timescale are studied. These include mixed-valence [M30(02CR)6L3lS, where M is either Fe or Mn, L is a substituted pyridine, and S is a solvate molecule such as C6H6, CHCI3, etc., and salts of the mixed-valence 1 ',1 '''-disubstituted biferrocenium cation. It is shown that it is not the level of intramolecular electronic coupling between metal centers which controls the rate of intramolecular ET. The environment about the mixed-valence complex controls the rate of ET. For salts of mixed-valence 1 ',1 '''-disubstituted biferrocenium cations the positioning of the counteranion relative to the cation controls the rate of ET. If the anion is positioned so that the two iron ions in a cation are inequivalent, the rate of ET is small and the cation is trapped in one valence description. In the case of Fe30 acetate complexes the positioning of the solvate molecule S can lead to valence trapping, even though only van der Waals interactions between the Sand mixed-valence Fe30 complexes exist. Valence detrapping, where the rate of ET increases appreciably, occurs frequently in a phase transition. In the solid-state intermolecular interactions valence trap complexes. As the temperature is increased, the coopenitive onset in a phase transition of motion associated with ligands, counterions, or even solvate molecules leads to valence detrapping. 57Fe Mossbauer, EPR, IR, solid-state 2H NMR and heat capacity data are used to probe these catastrophic events.

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Section: Sample History Dependence and Pol Ymorphsmentioning

confidence: 75%

Electron Transfer in Mixed-Valence Complexes in the Solid State

Hendrickson

1991

Mixed Valency Systems: Applications in Chemistry, Physics and Biology

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“…(68) but are stoichiometrically amalgamated in the crystal lattice play an important role for the intramolecular electron transfer event.…”

Section: Frenkel Theory Of Heterophase Fluctuations In Liquidsmentioning

confidence: 99%

“…A schematic drawing of the molecular packing in the valence-detrapped high-temperature phase of figure 20. (68) For simplicity, the acetato ligands are not drawn. As described previously, the space group of this crystal is R32.…”

Section: Frenkel Theory Of Heterophase Fluctuations In Liquidsmentioning

confidence: 99%

“…As required by the presence of the C 3 axes along which the metal complexes are stacked, the pyridine solvate molecules are disordered, with at least three orientational positions. On the other hand, solid-state 2 H NMR for the iron complex with deuterated pyridine solvate molecule studied by Hendrickson and his collaborators (68) revealed detailed molecular dynamics. As illustrated in figure 21(a), the molecular plane of the pyridine jumps among three positions about the crystallographic C 3 axis.…”

Section: Frenkel Theory Of Heterophase Fluctuations In Liquidsmentioning

confidence: 99%

“…As the result, the pyridine solvate molecule converts from being static to dynamically interconverting among twelve different orientations. (68) Now that the dynamics of the solvate molecule has been clarified, the transition entropy can be interpreted as follows. If each metal complex converts from being statically distorted in one state to interconverting dynamically between three vibronic states when the complex is heated from low temperatures, this contributes R ln 3 to the entropy gain.…”

Section: Frenkel Theory Of Heterophase Fluctuations In Liquidsmentioning

confidence: 99%

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Calorimetric investigations of phase transitions in which electrons are directly involved

Sorai

2002

The Journal of Chemical Thermodynamics

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Iron: Inorganic & Coordination ChemistryBased in part on the article Iron: Inorganic & Coordination Chemistry by Pelham N. Hawker & Martyn V. Twigg which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Burgess

Twigg

2005

Encyclopedia of Inorganic Chemistry

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Iron, the most abundant transition element in the biosphere, is essential in higher forms of life and its compounds have numerous industrial applications. The element has catalytic properties. Several simple iron compounds are industrially important, for example, large amounts of iron oxides are produced for pigment and magnetic recording media applications. Oxidation states ranging from −2 to +6 are known, the most familiar are +2 (ferrous iron) and +3 (ferric iron). Most common complexes are octahedral, although examples of higher (e.g. seven coordinate) and lower (e.g. tetrahedral and square planar) geometries are well known, as are a variety of mixed oxidation state compounds. Depending on ligands involved high‐ and low‐spin complexes can be formed, and temperature‐dependent spin‐state crossover complexes are well documented. The thermodynamics and kinetics of reactions of low‐spin iron(II) complexes with ligands such as 1,4‐diimines and CN − have been extensively studied. While low‐spin iron(II) is present in biological systems such as oxygenated heme centered oxygen carriers and thiolate clusters, iron(III) is more common. Thiolate‐containing iron clusters form readily, and here mixed oxidation states are a prominent feature that is exploited in some important electron transfer proteins. Microorganism iron uptake is facilitated by tris‐catecholate and tris‐hydroxamate ligands like enterobactin that have an extraordinarily high affinity for iron(III) that results in a dramatic enhancement of the 3+ relative to the 2+ state in terms of redox potential.

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Deuteron NMR study of lattice dynamics affecting the rate of intramolecular electron transfer in the iron acetato oxo pyridine mixed-valence complex [Fe3O(O2CCH3)6(py)3](py)

Cited by 79 publications

References 0 publications

Electron Transfer in Mixed-Valence Complexes in the Solid State

Electron Transfer in Mixed-Valence Complexes in the Solid State

Calorimetric investigations of phase transitions in which electrons are directly involved

Iron: Inorganic & Coordination ChemistryBased in part on the article Iron: Inorganic & Coordination Chemistry by Pelham N. Hawker & Martyn V. Twigg which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

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