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Aldehyde Deformylation by Nonheme Manganese(Ⅲ)-Peroxo Intermediates

Title
Aldehyde Deformylation by Nonheme Manganese(Ⅲ)-Peroxo Intermediates
Authors
김자영
Issue Date
2007
Department/Major
대학원 나노과학부
Publisher
이화여자대학교 대학원
Degree
Master
Abstract
Mononuclear metal complex는 최근 oxidation catalyst로써의 metal complex와 biological system에서 oxygen activating biomolecule의 반응 메커니즘을 이해하기 위한 흥미로운 연구이다. Nonheme iron enzyme에서, ferric-peroxo종은 Rieske dioxygenase에 의한 aromatic 화합물의 cis-dihydroxylation 반응으로써 나타났다. 본 연구에서는 macrocyclic tetradentate N4 리간드 TMC (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)를 사용하여 side-on peroxo의 Mn(TMC) intermediate를 생성시킴으로써 그 특성과 반응성을 연구했다. Side-on peroxo Mn(Ⅲ)종은 UV-vis spectrophotometer, electron paramagnetic resonance, electrospray ionization mass spectrometer의 다양한 분광학적 방법을 통해 특성화된다. Side-on peroxo Mn(Ⅲ)종은 ESI-MS에서 (m/z) 343.1을 나타내며, 이것은 [Mn^(Ⅲ)(η-O₂)(TMC)]^(+)의 isotope distribution pattern과 일치한다 (calculated m/z 343). 또한 ^(18)○ 실험을 통해(^(18)○-labeled hydrogen peroxide) m/z 347.1로 치환됨을 확인하였다. [Mn^(Ⅲ)(η-O₂)(TMC)]^(+) intermediate의 X-ray crystal 구조는 Manganese와 dioxygen의 공유 결합을 보여준다 (○-○ : 1.404 Å, Mn-O : 1.884 Å). Mn(Ⅱ) complex에 의한 aldehyde oxidation은 side-on Mn(III) peroxo complex의 aldehyde oxidation 메커니즘을 이해하기 위해 시도되었다.;Mononuclear metal complexes are recent interest for understanding the reaction mechanisms of oxygen activating biomolecules in biological systems and utilizing metal complexes as oxidation catalyst. In nonheme iron enzymes, ferric-peroxo species has been proposed as an active oxidant responsible for the cis-dihydroylation of aromatic compounds catalyzed by Rieske dioxygenases. We have reported the characterization and reactivity of a mononuclear Mn peroxo complex, bearing a macrocyclic tetradentate N4 ligand, TMC (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) were studied by side-on peroxo Mn(TMC) intermediate. The side-on peroxo Mn(Ⅲ) species are characterized with various spectroscopic techniques such as UV-vis spectrophotometer, electron paramagnetic resonance, and electrospray ionization mass spectrometer. The electrospray ionization mass spectrum (ESI-MS) of side-on peroxo Mn(Ⅲ) species exhibited a prominent ion at a mass-to-charge ratio (m/z) of 343.1, with mass and isotope distribution pattern corresponding to [Mn^(Ⅲ)(η-O₂)(TMC)]^(+) (calculated m/z of 343). The mass peak at 347.1 up-shifted accordingly upon introduction of ^(18)○ (^(18)○-labeled hydrogen peroxide used). The X-ray crystal structure of [Mn^(Ⅲ)(η-O₂)(TMC)]^(+) intermediate reveals a coordination of Mn with dioxygen, with a 1.404 Å distance of ○-○ and 1.884 Å distance of Mn-O. A catalytic aldehyde oxidation by Mn(Ⅱ) complex was demonstrated to understand mechanisms of the aldehyde oxidation by side-on Mn(Ⅲ) peroxo complex.
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일반대학원 > 화학·나노과학과 > Theses_Master
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