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Structural Characterization of a Series of N5-Ligated MnIV-Oxo Species

Massie, Allyssa A. ; Denler, Melissa C. ; Singh, Reena LU ; Sinha, Arup LU ; Nordlander, Ebbe LU and Jackson, Timothy A. (2020) In Chemistry - A European Journal 26(4). p.900-912
Abstract

Analysis of extended X-ray absorption fine structure (EXAFS) data for the MnIV-oxo complexes [MnIV(O)(DMMN4py)]2+, [MnIV(O)(2pyN2B)]2+, and [MnIV(O)(2pyN2Q)]2+ (DMMN4py=N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; 2pyN2B=(N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, and 2pyN2Q=N,N-bis(2-pyridyl)-N,N-bis(2-quinolylmethyl)methanamine) afforded Mn=O and Mn−N bond lengths. The Mn=O distances for [MnIV(O)(DMMN4py)]2+ and [MnIV(O)(2pyN2B)]2+ are 1.72 and 1.70 Å, respectively. In contrast, the Mn=O distance for... (More)

Analysis of extended X-ray absorption fine structure (EXAFS) data for the MnIV-oxo complexes [MnIV(O)(DMMN4py)]2+, [MnIV(O)(2pyN2B)]2+, and [MnIV(O)(2pyN2Q)]2+ (DMMN4py=N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; 2pyN2B=(N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, and 2pyN2Q=N,N-bis(2-pyridyl)-N,N-bis(2-quinolylmethyl)methanamine) afforded Mn=O and Mn−N bond lengths. The Mn=O distances for [MnIV(O)(DMMN4py)]2+ and [MnIV(O)(2pyN2B)]2+ are 1.72 and 1.70 Å, respectively. In contrast, the Mn=O distance for [MnIV(O)(2pyN2Q)]2+ was significantly longer (1.76 Å). We attribute this long distance to sample heterogeneity, which is reasonable given the reduced stability of [MnIV(O)(2pyN2Q)]2+. The Mn=O distances for [MnIV(O)(DMMN4py)]2+ and [MnIV(O)(2pyN2B)]2+ could only be well-reproduced using DFT-derived models that included strong hydrogen-bonds between second-sphere solvent 2,2,2-trifluoroethanol molecules and the oxo ligand. These results suggest an important role for the 2,2,2-trifluoroethanol solvent in stabilizing MnIV-oxo adducts. The DFT methods were extended to investigate the structure of the putative [MnIV(O)(N4py)]2+⋅(HOTf)2 adduct. These computations suggest that a MnIV-hydroxo species is most consistent with the available experimental data.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
DFT calculations, electronic structure, oxido ligands, spectroscopy, X-ray absorption spectroscopy
in
Chemistry - A European Journal
volume
26
issue
4
pages
13 pages
publisher
Wiley-VCH Verlag
external identifiers
  • pmid:31693757
  • scopus:85076723841
ISSN
0947-6539
DOI
10.1002/chem.201904434
language
English
LU publication?
yes
id
7ae4edb5-c845-43cc-9fb6-899419f763c5
date added to LUP
2020-01-10 12:03:02
date last changed
2021-02-17 06:53:47
@article{7ae4edb5-c845-43cc-9fb6-899419f763c5,
  abstract     = {<p>Analysis of extended X-ray absorption fine structure (EXAFS) data for the Mn<sup>IV</sup>-oxo complexes [Mn<sup>IV</sup>(O)(<sup>DMM</sup>N4py)]<sup>2+</sup>, [Mn<sup>IV</sup>(O)(2pyN2B)]<sup>2+</sup>, and [Mn<sup>IV</sup>(O)(2pyN2Q)]<sup>2+</sup> (<sup>DMM</sup>N4py=N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; 2pyN2B=(N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, and 2pyN2Q=N,N-bis(2-pyridyl)-N,N-bis(2-quinolylmethyl)methanamine) afforded Mn=O and Mn−N bond lengths. The Mn=O distances for [Mn<sup>IV</sup>(O)(<sup>DMM</sup>N4py)]<sup>2+</sup> and [Mn<sup>IV</sup>(O)(2pyN2B)]<sup>2+</sup> are 1.72 and 1.70 Å, respectively. In contrast, the Mn=O distance for [Mn<sup>IV</sup>(O)(2pyN2Q)]<sup>2+</sup> was significantly longer (1.76 Å). We attribute this long distance to sample heterogeneity, which is reasonable given the reduced stability of [Mn<sup>IV</sup>(O)(2pyN2Q)]<sup>2+</sup>. The Mn=O distances for [Mn<sup>IV</sup>(O)(<sup>DMM</sup>N4py)]<sup>2+</sup> and [Mn<sup>IV</sup>(O)(2pyN2B)]<sup>2+</sup> could only be well-reproduced using DFT-derived models that included strong hydrogen-bonds between second-sphere solvent 2,2,2-trifluoroethanol molecules and the oxo ligand. These results suggest an important role for the 2,2,2-trifluoroethanol solvent in stabilizing Mn<sup>IV</sup>-oxo adducts. The DFT methods were extended to investigate the structure of the putative [Mn<sup>IV</sup>(O)(N4py)]<sup>2+</sup>⋅(HOTf)<sub>2</sub> adduct. These computations suggest that a Mn<sup>IV</sup>-hydroxo species is most consistent with the available experimental data.</p>},
  author       = {Massie, Allyssa A. and Denler, Melissa C. and Singh, Reena and Sinha, Arup and Nordlander, Ebbe and Jackson, Timothy A.},
  issn         = {0947-6539},
  language     = {eng},
  month        = {01},
  number       = {4},
  pages        = {900--912},
  publisher    = {Wiley-VCH Verlag},
  series       = {Chemistry - A European Journal},
  title        = {Structural Characterization of a Series of N5-Ligated Mn<sup>IV</sup>-Oxo Species},
  url          = {http://dx.doi.org/10.1002/chem.201904434},
  doi          = {10.1002/chem.201904434},
  volume       = {26},
  year         = {2020},
}