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Title: Crystal structure of a synthetic high-valent complex with an Fe{sub 2}({mu}-O){sub 2} diamond core. Implications for the core structures of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X

Abstract

In their efforts to model high-valent intermediates in the oxygen activation cycles of nonheme diiron enzymes such as methane monooxygenase (MMOH-Q) and ribonucleotide reductase (RNR R2-X), the authors have synthesized and spectroscopically characterized a series of bis({mu}-oxo)diiron(III,IV) complexes, [Fe{sub 2}({mu}-O){sub 2}(L){sub 2}](ClO{sub 4}){sub 3}, where L is tris(2-pyridylmethyl)amine (TPA) or its ring-alkylated derivatives. They now report the crystal structure of [Fe{sub 2}({mu}-O){sub 2}(5-Et{sub 3}-TPA){sub 2}](ClO{sub 4}){sub 3} (2), the first example of a structurally characterized reactive iron(IV)-oxo species, which provides accurate metrical parameters for the diamond core structure proposed for this series of complexes. Complex 2 has Fe-{mu}-O distances of 1.805(3) {angstrom} and 1.860(3) {angstrom}, an Fe-Fe distance of 2.683(1) {angstrom}, and an Fe-{mu}-O-Fe angle of 94.1(1){degree}. The EXAFS spectrum of 2 can be fit well with a combination of four shells: 1 O at 1.82 {angstrom}, 2--3 N at 2.03 {angstrom}, 1 Fe at 2.66 {angstrom}, and 7 C at 2.87 {angstrom}. The distances obtained are in very good agreement with the crystal structure data for 2, though the coordination numbers for the first coordination sphere are underestimated. The EXAFS spectra of MMOH-Q and RNR R2-X contain features that match well with those of 2 (except for the multi-carbonmore » shell at 2.87 {angstrom} arising from pyridyl carbons which are absent in the enzymes), suggesting that an Fe{sub 2}({mu}-O){sub 2} core may be a good candidate for the core structures of the enzyme intermediates. The implications of these studies are discussed.« less

Authors:
; ; ; ;  [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States)
Publication Date:
OSTI Identifier:
684311
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 121; Journal Issue: 22; Other Information: PBD: 9 Jun 1999
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; ENZYMES; HEME; CRYSTAL STRUCTURE; DIAMONDS; RIBOSIDES; IRON COMPLEXES

Citation Formats

Hsu, H F, Dong, Y, Shu, L, Young, Jr, V G, and Que, L Jr. Crystal structure of a synthetic high-valent complex with an Fe{sub 2}({mu}-O){sub 2} diamond core. Implications for the core structures of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X. United States: N. p., 1999. Web. doi:10.1021/ja983666q.
Hsu, H F, Dong, Y, Shu, L, Young, Jr, V G, & Que, L Jr. Crystal structure of a synthetic high-valent complex with an Fe{sub 2}({mu}-O){sub 2} diamond core. Implications for the core structures of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X. United States. https://doi.org/10.1021/ja983666q
Hsu, H F, Dong, Y, Shu, L, Young, Jr, V G, and Que, L Jr. Wed . "Crystal structure of a synthetic high-valent complex with an Fe{sub 2}({mu}-O){sub 2} diamond core. Implications for the core structures of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X". United States. https://doi.org/10.1021/ja983666q.
@article{osti_684311,
title = {Crystal structure of a synthetic high-valent complex with an Fe{sub 2}({mu}-O){sub 2} diamond core. Implications for the core structures of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X},
author = {Hsu, H F and Dong, Y and Shu, L and Young, Jr, V G and Que, L Jr},
abstractNote = {In their efforts to model high-valent intermediates in the oxygen activation cycles of nonheme diiron enzymes such as methane monooxygenase (MMOH-Q) and ribonucleotide reductase (RNR R2-X), the authors have synthesized and spectroscopically characterized a series of bis({mu}-oxo)diiron(III,IV) complexes, [Fe{sub 2}({mu}-O){sub 2}(L){sub 2}](ClO{sub 4}){sub 3}, where L is tris(2-pyridylmethyl)amine (TPA) or its ring-alkylated derivatives. They now report the crystal structure of [Fe{sub 2}({mu}-O){sub 2}(5-Et{sub 3}-TPA){sub 2}](ClO{sub 4}){sub 3} (2), the first example of a structurally characterized reactive iron(IV)-oxo species, which provides accurate metrical parameters for the diamond core structure proposed for this series of complexes. Complex 2 has Fe-{mu}-O distances of 1.805(3) {angstrom} and 1.860(3) {angstrom}, an Fe-Fe distance of 2.683(1) {angstrom}, and an Fe-{mu}-O-Fe angle of 94.1(1){degree}. The EXAFS spectrum of 2 can be fit well with a combination of four shells: 1 O at 1.82 {angstrom}, 2--3 N at 2.03 {angstrom}, 1 Fe at 2.66 {angstrom}, and 7 C at 2.87 {angstrom}. The distances obtained are in very good agreement with the crystal structure data for 2, though the coordination numbers for the first coordination sphere are underestimated. The EXAFS spectra of MMOH-Q and RNR R2-X contain features that match well with those of 2 (except for the multi-carbon shell at 2.87 {angstrom} arising from pyridyl carbons which are absent in the enzymes), suggesting that an Fe{sub 2}({mu}-O){sub 2} core may be a good candidate for the core structures of the enzyme intermediates. The implications of these studies are discussed.},
doi = {10.1021/ja983666q},
url = {https://www.osti.gov/biblio/684311}, journal = {Journal of the American Chemical Society},
number = 22,
volume = 121,
place = {United States},
year = {1999},
month = {6}
}