A Nonheme Thiolate-Ligated Cobalt Superoxo Complex: Synthesis and Spectroscopic Characterization, Computational Studies, and Hydrogen Atom Abstraction Reactivity
The synthesis and characterization of a Co(II) dithiolato complex Co(Me TACN)(S SiMe ) (1) are reported. Reaction of 1 with O generates a rare thiolate-ligated cobalt-superoxo species Co(O )(Me TACN)(S SiMe ) (2) that was characterized spectroscopically and structurally by resonance Raman, EPR, and...
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| Vydáno v: | Journal of the American Chemical Society Ročník 141; číslo 8; s. 3641 |
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| Hlavní autoři: | , , , , , |
| Médium: | Journal Article |
| Jazyk: | angličtina |
| Vydáno: |
United States
27.02.2019
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| ISSN: | 1520-5126, 1520-5126 |
| On-line přístup: | Zjistit podrobnosti o přístupu |
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| Shrnutí: | The synthesis and characterization of a Co(II) dithiolato complex Co(Me
TACN)(S
SiMe
) (1) are reported. Reaction of 1 with O
generates a rare thiolate-ligated cobalt-superoxo species Co(O
)(Me
TACN)(S
SiMe
) (2) that was characterized spectroscopically and structurally by resonance Raman, EPR, and X-ray absorption spectroscopies as well as density functional theory. Metal-superoxo species are proposed to S-oxygenate metal-bound thiolate donors in nonheme thiol dioxygenases, but 2 does not lead to S-oxygenation of the intramolecular thiolate donors and does not react with exogenous sulfur donors. However, complex 2 is capable of oxidizing the O-H bonds of 2,2,6,6-tetramethylpiperidin-1-ol derivatives via H atom abstraction. Complementary proton-coupled electron-transfer reactivity is seen for 2 with separated proton/reductant pairs. The reactivity studies indicate that 2 can abstract H atoms from weak X-H bonds with bond dissociation free energy (BDFE) ≤ 70 kcal mol
. DFT calculations predict that the putative Co(OOH) product has an O-H BDFE = 67 kcal mol
, which matches the observed pattern of reactivity seen for 2. These data provide new information regarding the selectivity of S-oxygenation versus H atom abstraction in thiolate-ligated nonheme metalloenzymes that react with O
. |
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| Bibliografie: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 1520-5126 1520-5126 |
| DOI: | 10.1021/jacs.8b13134 |