Effect of Lattice Dynamics on Intramolecular Electron-Transfer Rates in Mixed-Valence Complexes

Hendrickson, David N.; Oh, Seung M.; Dong, Tungalag; Kambara, Takeshi; Cohn, Michelle J.; Moore, Michael F.

doi:10.1080/02603598508072271

Cited by 83 publications

(33 citation statements)

References 29 publications

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“…Indeed, the Mçssbauer results are consistent with this interpretation in which fast electron transfer is only evident with these counterions in the temperature range studied. The special case of [ 4 ] underlines the fact that static disorder effects also have to be taken into consideration in the interpretation of X-ray structural data, and environmental conditions, such as temperature and lattice dynamics, [67] may impact electron transfer, which for […”

Section: Resultsmentioning

confidence: 99%

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)₂{μ‐C₁₀H₆(BPh)₂}]⁺

Venkatasubbaiah

Doshi

Nowik

et al. 2007

Chemistry A European J

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A series of mixed-valent (MV) complexes [(FeCp)2(mu-C10H6(BPh)2)]+X ([1+]X; X=I 5, PF6, SbF6, B(C6F5)4) were prepared by oxidation of diboradiferrocene [(FeCp)2(mu-C10H6(BPh)2)] (1) with I 2, AgPF6, and AgSbF6, respectively, and through anion exchange of the I 5(-) salt with [Li(Et2O)x][B(C6F5)4] in the case of X=B(C6F5)4. The MV state of the cation was investigated in solution by multinuclear NMR spectroscopy, CV, and UV/Vis-NIR absorption spectroscopy, and in the solid state by IR spectroscopy, single-crystal X-ray crystallography, and Mössbauer spectroscopy. The cyclic voltammogram of 1 shows two distinct redox waves with a large redox splitting of Delta E=510 mV in CH2Cl2 and the NIR spectrum for the mono-oxidized species displays an intervalence charge-transfer band at around 1500 to 1700 nm depending on the specific counterion present. The X-ray crystal structures of [1+]X show inversion-symmetric cations with X=I 5 and B(C6F5)4 and unsymmetric valence-trapped structures composed of one ferrocene and one ferrocenium moiety with X=PF6 and SbF6. Mössbauer data for X=PF6 are consistent with valence trapping at all temperatures between 90 and 343 K. In comparison, fast electron transfer is evident on the Mössbauer timescale for X=I 5 and temperature-dependent behavior is observed for X=B(C6F5)4. The anion dependence of the X-ray structural and Mössbauer data is discussed in the context of crystal symmetry and the possibility of static and dynamic disorder effects is considered.

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Section: Resultsmentioning

confidence: 99%

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)₂{μ‐C₁₀H₆(BPh)₂}]⁺

Venkatasubbaiah

Doshi

Nowik

et al. 2007

Chemistry A European J

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“…In the case of outer-sphere ET between metal complexes in solution sluggish motion of solvent structure and/or counterions could be partially rate determining in non-adiabatic processes [2]. The study of intramolecular ET events in mixed-valence complexes in the solid state has given fundamental information about environmental effects on rates of electron transfer [3]. Mixed-valence complexes are electronically labile.…”

Section: Introductionmentioning

confidence: 99%

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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“…[2] Biferrocene, composed of two ferrocene units, produces a monocation (D + ) and a dication (D 2+ ) by oxidation. [3] During our research on biferrocenium charge-transfer salts, [4] we found that a charge-transfer salt comprising D = dineopentylbiferrocene (1) and A = fluorotetracyanoquinodimethane (F 1 TCNQ), [(1)(F 1 TCNQ) 3 ) at around 120 K (Figure 1b). [4a] The phase transition is of the first order and accompanies a two-phase coexistence over a wide temperature range (100-150 K).…”

Section: − ) To a Divalent State (D 2+ A 3 2−mentioning

confidence: 99%

“…This phenomenon is ascribed to the smaller electron affinity of the acceptor trimers containing TCNQ; namely, only (F 1 TCNQ) 3 − had sufficient electron affinity to receive an electron to become A 3 2− , whereas the other trimers containing TCNQ ([(F 1 TCNQ) m (TCNQ) 3−m ] − ; m = 0, 1, and 2) remained monovalent in the low-temperature phase. The ratio of (F 1 TCNQ) 3 − and the other trimers was predicted to be 51:49 (= x 3 :(1−x) 3 ) for x = 0.8, which is in agreement with the ratio determined by Mössbauer spectroscopy. The low-temperature phase of the molecular alloys is hence regarded as an intermediate phase containing both the monovalent and divalent species.…”

Section: − ) To a Divalent State (D 2+ A 3 2−mentioning

confidence: 99%

Chemical control of the monovalent–divalent electron-transfer phase transition in biferrocenium–TCNQ salts

et al. 2014

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Effect of Lattice Dynamics on Intramolecular Electron-Transfer Rates in Mixed-Valence Complexes

Cited by 83 publications

References 29 publications

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)₂{μ‐C₁₀H₆(BPh)₂}]⁺

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)₂{μ‐C₁₀H₆(BPh)₂}]⁺

Electron Transfer in Mixed-Valence Complexes in the Solid State

Chemical control of the monovalent–divalent electron-transfer phase transition in biferrocenium–TCNQ salts

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Effect of Lattice Dynamics on Intramolecular Electron-Transfer Rates in Mixed-Valence Complexes

Cited by 83 publications

References 29 publications

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)2{μ‐C10H6(BPh)2}]+

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)2{μ‐C10H6(BPh)2}]+

Electron Transfer in Mixed-Valence Complexes in the Solid State

Chemical control of the monovalent–divalent electron-transfer phase transition in biferrocenium–TCNQ salts

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Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)₂{μ‐C₁₀H₆(BPh)₂}]⁺

Examination of the Mixed‐Valence State of the Doubly Boron‐Bridged Diferrocene Cation [(FeCp)₂{μ‐C₁₀H₆(BPh)₂}]⁺