TY - JOUR
T1 - Di- and tetrairon(III) μ-oxido complexes of an N3S-donor ligand
T2 - Catalyst precursors for alkene oxidations
AU - Das, Biswanath
AU - Al-Hunaiti, Afnan
AU - Sánchez-Eguía, Brenda N.
AU - Zeglio, Erica
AU - Demeshko, Serhiy
AU - Dechert, Sebastian
AU - Braunger, Steffen
AU - Haukka, Matti
AU - Repo, Timo
AU - Castillo, Ivan
AU - Nordlander, Ebbe
PY - 2019/3/1
Y1 - 2019/3/1
N2 -
The new di- and tetranuclear Fe(III) μ-oxido complexes [Fe
4
(μ-O)
4
(PTEBIA)
4
](CF
3
SO
3
)
4
(CH
3
CN)
2
] (1a), [Fe
2
(μ-O)Cl
2
(PTEBIA)
2
](CF
3
SO
3
)
2
(1b), and [Fe
2
(μ-O)(HCOO)
2
(PTEBIA)
2
](ClO
4
)
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 μ-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) Å. 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 1b show broad sulfur-to-iron 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 H
2
O
2
/CH
3
COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H
2
O
2
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.
AB -
The new di- and tetranuclear Fe(III) μ-oxido complexes [Fe
4
(μ-O)
4
(PTEBIA)
4
](CF
3
SO
3
)
4
(CH
3
CN)
2
] (1a), [Fe
2
(μ-O)Cl
2
(PTEBIA)
2
](CF
3
SO
3
)
2
(1b), and [Fe
2
(μ-O)(HCOO)
2
(PTEBIA)
2
](ClO
4
)
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 μ-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) Å. 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 1b show broad sulfur-to-iron 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 H
2
O
2
/CH
3
COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H
2
O
2
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.
KW - Fe-S interaction
KW - Homogeneous catalysis
KW - Iron-oxo complex
KW - Oxidation
KW - Thioether
U2 - 10.3389/fchem.2019.00097
DO - 10.3389/fchem.2019.00097
M3 - Article
C2 - 30881952
AN - SCOPUS:85064708910
SN - 2296-2646
VL - 7
JO - Frontiers in Chemistry
JF - Frontiers in Chemistry
IS - MAR
M1 - 97
ER -