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

Research output: Contribution to journalArticle

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 [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.

Details

Authors
  • Allyssa A. Massie
  • Melissa C. Denler
  • Reena Singh
  • Arup Sinha
  • Ebbe Nordlander
  • Timothy A. Jackson
Organisations
External organisations
  • University of Kansas Lawrence
  • Vellore Institute of Technology University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Theoretical Chemistry

Keywords

  • DFT calculations, electronic structure, oxido ligands, spectroscopy, X-ray absorption spectroscopy
Original languageEnglish
Pages (from-to)900-912
Number of pages13
JournalChemistry - A European Journal
Volume26
Issue number4
Early online date2019
Publication statusPublished - 2020 Jan 16
Publication categoryResearch
Peer-reviewedYes