Multiple-edge XAS studies of cyanide-bridged iron-copper molecular assemblies relevant to cyanide-inhibited heme-copper oxidases using four-body multiple-scattering analysis
- Stanford Univ., CA (United States)
- European Synchrotron Radiation Facility, Grenoble (France)
- Harvard Univ., Cambridge, MA (United States)
A pair of cyanide-bridged iron-copper molecular assemblies relevant to cyanide-inhibited heme-copper oxidases has been studied by X-ray absorption spectroscopy at both Fe and Cu K-edges. These two complexes, [(py)(OEP)Fe-CN-Cu(Me{sub 6}tren)]{sup 2+} (2) and [(py)(OEP)Fe-CN-Cu(TIM)]{sup 2+} (3), contain a unique four-body Fe-C-N-Cu bridge with an Fe-C-N angle of 179{degree}. They, however, differ significantly in the Cu-N-C angle (174{degree} in 2 and 147{degree} in 3). We have calculated theoretical four-body MS signals for the bridge configuration and other four-body pathways in the structures, and performed least-square fittings of the theoretical signals to the experimental data using the GNXAS programs. A strong long-range Fe...Cu interaction (4.94 A) has been observed from both the Fe and Cu K-edge data for 2. GNXAS analysis shows that this long-range interaction is attributed to the MS amplitude enhancement form the linear four-body Fe-C-N-Cu configuration. This interaction is not observable from the Fe and Cu K-edge data for 3 where the angle deviates significantly from linearity. An angle-dependence study of MS effects on the Cu-N-C angle shows that there is a large enhancement of MS intensity where the angle approaches linearity, and that this MS effect is negligible when the angle is below nearly 160{degree}. Essentially no Fe-Cu interaction is detectable for a configuration with such an angle. 33 refs., 11 figs., 2 tabs.
- OSTI ID:
- 466373
- Journal Information:
- Journal of the American Chemical Society, Vol. 119, Issue 10; Other Information: PBD: 12 Mar 1997
- Country of Publication:
- United States
- Language:
- English
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