Structural Characterization of a Series of N5‐Ligated Mn ^IV ‐Oxo Species

Journal Article · 19 December 2019 · Chemistry - A European Journal

DOI: https://doi.org/10.1002/chem.201904434 · OSTI ID:1580145

Massie, Allyssa A. ^[1]; Denler, Melissa C. ^[1]; Singh, Reena ^[2]; Sinha, Arup ^[3]; Nordlander, Ebbe ^[2]; Jackson, Timothy A.  ^[1]

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1. Department of Chemistry and Center for Environmentally, Beneficial Catalysis The University of Kansas 1567 Irving Hill Road Lawrence KS 66045 USA
2. Chemical Physics Department of Chemistry Lund University Box 124 221 00 Lund Sweden
3. Chemical Physics Department of Chemistry Lund University Box 124 221 00 Lund Sweden, Department of Chemistry School of Advanced Science Vellore Institute of Technology Vellore 632014 Tamil Nadu India

Abstract Analysis of extended X‐ray absorption fine structure (EXAFS) data for the Mn ^IV ‐oxo complexes [Mn ^IV (O)( ^DMM N4py)] ²⁺ , [Mn ^IV (O)(2pyN2B)] ²⁺ , and [Mn ^IV (O)(2pyN2Q)] ²⁺ ( ^DMM 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 ^IV (O)( ^DMM N4py)] ²⁺ and [Mn ^IV (O)(2pyN2B)] ²⁺ are 1.72 and 1.70 Å, respectively. In contrast, the Mn=O distance for [Mn ^IV (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 [Mn ^IV (O)(2pyN2Q)] ²⁺ . The Mn=O distances for [Mn ^IV (O)( ^DMM N4py)] ²⁺ and [Mn ^IV (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 Mn ^IV ‐oxo adducts. The DFT methods were extended to investigate the structure of the putative [Mn ^IV (O)(N4py)] ²⁺ ⋅(HOTf) ₂ adduct. These computations suggest that a Mn ^IV ‐hydroxo species is most consistent with the available experimental data.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-76SF00515; SC0016359
• OSTI ID: 1580145
• Journal Information: Chemistry - A European Journal, Journal Name: Chemistry - A European Journal Journal Issue: 4 Vol. 26; ISSN 0947-6539
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: Germany
• Language: English