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Title: Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

Abstract

The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ ) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described as a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.

Authors:
ORCiD logo [1];  [2];  [2];  [3];  [2];  [4];  [2]
  1. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Center for High Pressure Science & Technology Advanced Research, Shanghai (People's Republic of China)
  4. Univ. of Colorado, Boulder, CO (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1360788
Grant/Contract Number:  
P41 GM103393; AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 56; Journal Issue: 2; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Liang, H. Winnie, Kroll, Thomas, Nordlund, Dennis, Weng, Tsu -Chien, Sokaras, Dimosthenis, Pierpont, Cortlandt G., and Gaffney, Kelly J. Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies. United States: N. p., 2016. Web. doi:10.1021/acs.inorgchem.6b01666.
Liang, H. Winnie, Kroll, Thomas, Nordlund, Dennis, Weng, Tsu -Chien, Sokaras, Dimosthenis, Pierpont, Cortlandt G., & Gaffney, Kelly J. Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies. United States. doi:10.1021/acs.inorgchem.6b01666.
Liang, H. Winnie, Kroll, Thomas, Nordlund, Dennis, Weng, Tsu -Chien, Sokaras, Dimosthenis, Pierpont, Cortlandt G., and Gaffney, Kelly J. Fri . "Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies". United States. doi:10.1021/acs.inorgchem.6b01666. https://www.osti.gov/servlets/purl/1360788.
@article{osti_1360788,
title = {Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies},
author = {Liang, H. Winnie and Kroll, Thomas and Nordlund, Dennis and Weng, Tsu -Chien and Sokaras, Dimosthenis and Pierpont, Cortlandt G. and Gaffney, Kelly J.},
abstractNote = {The valence tautomeric states of Co(phen)(3,5-DBQ)2 and Co(tmeda)(3,5-DBQ)2, where 3,5-DBQ is either the semiquinone (SQ–) or catecholate (Cat2–) form of 3,5-di-tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described as a low-spin CoIII configuration and the high-temperature valence tautomer as a high-spin CoII configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ– in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.},
doi = {10.1021/acs.inorgchem.6b01666},
journal = {Inorganic Chemistry},
issn = {0020-1669},
number = 2,
volume = 56,
place = {United States},
year = {2016},
month = {12}
}

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