Reactivity Studies on FeIII-(O22-)-CuII Compounds: Influence of the Ligand Architecture and Copper Ligand Denticity
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- 作者：Eduardo E. Chufá ; n ; Biplab Mondal ; Thirumanavelan Gandhi ; Eunsuk Kim ; Nick D. Rubie ; Pierre Moë ; nne-Loccoz ; Kenneth D. Karlin
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：August 6, 2007
- 年：2007
- 卷：46
- 期：16
- 页码：6382 - 6394
- 全文大小：406K
- 年卷期：v.46,no.16(August 6, 2007)
- ISSN：1520-510X
文摘
Heme-Cu/O2 adducts are of interest in the elucidation of the fundamental metal-O2 chemistry occurring in heme-Cu enzymes which effect reductive O-O cleavage of dioxygen to water. In this report, the chemistry of four heme-peroxo-copper [FeIII-(O22-)-CuII]+ complexes (1-4), varying in their ligand architecture, copper-ligand denticity, orboth and thus their structures and physical properties are compared in their reactivity toward CO, PPh3, acids,cobaltocene, and phenols. In 1 and 2, the copper(II) ligand is N4-tetradentate, and the peroxo unit is bound side-onto iron(III) and end-on to the copper(II). In contrast, 3 and 4 contain a N3-tridentate copper(II) ligand, and theperoxo unit is bound side-on to both metal ions. CO "displaces" the peroxo ligand from 2-4 to form reducedCO-FeII and CO-CuI species. PPh3 reacts with 3 and 4 displacing the peroxide ligand from copper, forming(porphyrinate)FeIII-superoxide plus CuI-PPh3 species. Complex 2 does not react with PPh3, and surprisingly, 1reacts neither with PPh3 nor CO, exhibiting remarkable stability toward these reagents. The behavior of 1 and 2compared to that of 3 and 4 correlates with the different denticity of the copper ligand (tetra vs tridentate). Complexes1-4 react with HCl releasing H2O2, demonstrating the basic character of the peroxide ligand. Cobaltocene causesthe two-electron reduction of 1-4 giving the corresponding 
ntities/mgr.gif">-oxo [FeIII-(O2-)-CuII]+ complexes, in contrast to thefindings for other heme-peroxo-copper species of different design. With t-butyl-substituted phenols, no reactionoccurs with 1-4. The results described here emphasize how ligand design and variations influence and control notonly the structure and physical properties but also the reactivity patterns for heme-Cu/O2 adducts. Implications forfuture investigations of protonated heme/Cu-peroxo complexes, low-spin analogues, and ultimately O-O cleavagechemistry are discussed.
ntities/mgr.gif">-oxo [FeIII-(O2-)-CuII]+ complexes, in contrast to thefindings for other heme-peroxo-copper species of different design. With t-butyl-substituted phenols, no reactionoccurs with 1-4. The results described here emphasize how ligand design and variations influence and control notonly the structure and physical properties but also the reactivity patterns for heme-Cu/O2 adducts. Implications forfuture investigations of protonated heme/Cu-peroxo complexes, low-spin analogues, and ultimately O-O cleavagechemistry are discussed.