Electrochemical variational study of donor/acceptor orbital mixing and electronic coupling in cyanide-bridged mixed-valence complexes

Journal Article · Wed Jul 08 00:00:00 EDT 1992 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00040a034· OSTI ID:7180278

Dong, Yuhuua; Hupp, J T ^[1]

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1. Northwestern Univ., Evanston, IL (United States)

Cyanide-bridged mixed-valence complexes are interesting examples of strongly covalently linked redox systems which, nevertheless, exist in valence-localized form. As mixed-valence species, they display fairly intense intervalence (or metal-to-metal) charge-transfer transitions ([epsilon] [approx] 3000 M[sup [minus]1] cm[sup [minus]1]), which tend to be shifted toward the visible region from the near-infrared on account of substantial redox asymmetry. The authors have recently succeeded in obtaining (by femtosecond transient absorbance spectroscopy) a direct measure of the thermal kinetics (k[sub ET]) of the highly exothermic back-electron-transfer reaction which follows intervalence excitation in one of these complexes, (H[sub 3]N)[sub 5]Ru-NC-Fe(CN)[sub 5][sup [minus]]. With the available structural, kinetic, and thermodynamic information, the only additional ingredient needed to complete the picture of intramolecular electron transfer is a knowledge of initial-state/final-state electronic coupling. From the work of Burewicz and Haim, one estimate of the size of the coupling element (H[sub if]) is, in fact, already available. They report H[sub if] = 1500 cm[sup [minus]1], on the basis of a Hush-Mulliken analysis of the oscillator strength for intervalence absorption. The purpose of this paper is to report on an alternative electrochemical investigation of electronic coupling as well as donor/acceptor orbital mixing - with particular emphasis on comparisons to the oscillator strength method.

• DOE Contract Number: FG02-87ER13808
• OSTI ID: 7180278
• Journal Information: Inorganic Chemistry; (United States), Vol. 31:14; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RUTHENIUM COMPLEXES
ELECTROCHEMISTRY
ELECTRONIC STRUCTURE
BINDING ENERGY
CHARGE TRANSPORT
CHEMICAL PREPARATION
ELECTRIC POTENTIAL
ELECTRON-ELECTRON COUPLING
ELECTRONS
LIGANDS
QUALITATIVE CHEMICAL ANALYSIS
RAMAN SPECTRA
VALENCE
VOLTAMETRY
CHEMICAL ANALYSIS
CHEMISTRY
COMPLEXES
COUPLING
ELEMENTARY PARTICLES
ENERGY
FERMIONS
LEPTONS
SPECTRA
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400400* - Electrochemistry