Donor/acceptor coupling in mixed-valent dinuclear iron polypyridyl complexes: experimental and theoretical considerations

Journal Article · Wed Jun 05 04:00:00 EDT 1996 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja954297q· OSTI ID:264046

Elliott, C M; Derr, D L; Ferrere, S ^[1]; Newton, M D; Liu, Y P ^[2]

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1. Colorado State Univ., Ft. Collins, CO (United States)
2. Brookhaven National Lab., Upton, NY (United States)

Coupling between donor and acceptor orbitals for optically-induced intervalence electron transfer processes has been considered for a series of rigid mixed-valent dinuclear tris(2,2`-bipyridine)iron complexes. Each of the four complexes considered ontains three saturated bridges which link the two tris(2,2`-bipyridine)iron moieties. The bridging linkages are -CH{sub 2}CH{sub 2}-, -CH{sub 2}CH{sub 2}CH{sub 2}-, -CH{sub 2}OCH{sub 2}-. Despite differences in the composition of the bridges X-ray diffraction and/or molecular dynamics calculations show that the metal-metal separation and relative bipyridine orientations among all four complexes are nearly identical. Consequently, the only factor which differs significantly among these complexes and which might affect the donor-acceptor coupling in the mixed-valent forms is their connectivity. Theses complexes thus provide a unique opportunity to focus on potential superexchange coupling in the absence of ambiguities introduced by other structural and energetic considerations. Theories developed by Mulliken and Hush have been applied to intervalence charge-transfer transitions in order to obtain values of the coupling matrix elements, H{sub 12}. Configuration interaction calculations were also carried out for each of the [Fe{sub 2}(L){sub 3}]{sub 5+} complexes to provide theoretical values of H{sub 12} and the effective donor/acceptor separation distances (r{sub DA}). Experimental and theoretical results for H{sub 12} are in excellent agreement. 31 refs., 3 figs., 4 tabs.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 264046
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 22 Vol. 118; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
CALCULATION METHODS
CONFIGURATION INTERACTION
ELECTRON TRANSFER
ELECTRON-ELECTRON COUPLING
INFRARED SPECTRA
IRON COMPLEXES
MOLECULAR MODELS
ORGANOMETALLIC COMPOUNDS
PYRIDYL RADICALS