부산대학교 도서관

Nonheme oxoiron(IV) complexes can serve as synthons for generating heterobimetallic oxo-bridged dimetal complexes by reaction with divalent metal complexes. The formation of Fe-O-Cr and Fe-O-Mn complexes is described herein. The latter complexes may serve as models for the Fe-X-Mn active sites of an emerging class of Fe/Mn enzymes represented by the Class 1c ribonucleotide reductase from Chlamydia trachomatis and the R2-like ligand-binding oxidase (R2lox) found in Mycobacterium tuberculosis. These synthetic complexes have been characterized by UV-Vis, resonance Raman, and X-ray absorption spectroscopy, as well as electrospray mass spectrometry. The Fe-O-Cr complexes exhibit a three-band UV-Vis pattern that differs from the simpler features associated with Fe-O-Fe complexes. The positions of these features are modulated by the nature of the supporting polydentate ligand on the iron center, and their bands intensify dramatically in two examples upon the binding of an axial cyanate or thiocyanate ligand trans to the oxo bridge. In contrast, the Fe-O-Mn complexes resemble Fe-O-Fe complexes more closely. Resonance Raman characterization of the Fe-O-M complexes reveals an O-sensitive vibration in the range of 760-890 cm. This feature has been assigned to the asymmetric Fe-O-M stretching mode and correlates reasonably with the Fe-O bond distance determined by EXAFS analysis. The likely binding of an acetate as a bridging ligand to the Fe-O-Mn complex 12 lays the foundation for further efforts to model the heterobimetallic active sites of Fe/Mn enzymes. [ABSTRACT FROM AUTHOR]