Di- and Tetrairon(III) mu-Oxido Complexes of an N3S-Donor Ligand : Catalyst Precursors for Alkene Oxidations

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Das , B , Al-Hunaiti , A , Sanchez-Eguia , B N , Zeglio , E , Demeshko , S , Dechert , S , Braunger , S , Haukka , M , Repo , T , Castillo , I & Nordlander , E 2019 , ' Di- and Tetrairon(III) mu-Oxido Complexes of an N3S-Donor Ligand : Catalyst Precursors for Alkene Oxidations ' , Frontiers in Chemistry , vol. 7 , 97 . https://doi.org/10.3389/fchem.2019.00097

Title: Di- and Tetrairon(III) mu-Oxido Complexes of an N3S-Donor Ligand : Catalyst Precursors for Alkene Oxidations
Author: Das, Biswanath; Al-Hunaiti, Afnan; Sanchez-Eguia, Brenda N.; Zeglio, Erica; Demeshko, Serhiy; Dechert, Sebastian; Braunger, Steffen; Haukka, Matti; Repo, Timo; Castillo, Ivan; Nordlander, Ebbe
Contributor: University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
Date: 2019-03-01
Language: eng
Number of pages: 12
Belongs to series: Frontiers in Chemistry
ISSN: 2296-2646
URI: http://hdl.handle.net/10138/300267
Abstract: The new di- and tetranuclear Fe(III) mu-oxido complexes [Fe-4(mu-O)(4) (PTEBIA)(4)]CF3SO3)(4)(CH3CN)(2)] (1a) , [Fe-2(mu-O)Cl-2(PTEBIA)(2)(CF3SO3)(2) (1b), and [Fe-2(mu-O)(HCOO)(2)(PTEBIA)(2)](ClO4)(2) (MeOH) (2) were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thiO)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex 1a features four mu-oxido bridges, while in dinuclear 1b, the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) angstrom . In 2, two Fe(III) centers are bridged by one oxido and two formate units, the latter likely formed by methanol oxidation. Complexes 1a and 1 b show broad sulfur-toiron charge transfer bands around 400-430 nm at room temperature, consistent with mononuclear structures featuring Fe-S interactions. In contrast, acetonitrile solutions of 2 display a sulfur-to-iron charge transfer band only at low temperature (228 K) upon addition of H2O2/CH3COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H2O2 as oxidant, but with low product selectivity. High valent iron-oxo intermediates could not be detected by UV-vis spectroscopy or ESI mass spectrometry. Rather, evidence suggest preferential ligand oxidation, in line with the relatively low selectivity and catalytic activity observed in the reactions.
Subject: Fe-S interaction
oxidation
homogeneous catalysis
thioether
iron-oxo complex
NONHEME IRON CATALYSTS
FUNCTIONAL-MODEL
ACTIVE-SITE
COPPER-COMPLEXES
SULFUR
OXO
COORDINATION
MECHANISM
PEROXIDE
ACID
116 Chemical sciences
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