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Title: Electronic structure and reactivity studies of a nonsymmetric one-electron oxidized Cu II bis-phenoxide complex

Abstract

Here, the tetradentate mixed imino/amino phenoxide ligand (N-(3,5-di- tert-butylsalicylidene)-N'-(2-hydroxyl-3,5-di-tert-butylbenzyl))- trans-1,2-cyclohexanediamine (salalen) was complexed with Cu II, and the resulting Cu complex (2) was characterized by a number of experimental techniques and theoretical calculations. Two quasi-reversible redox processes for 2, as observed by cyclic voltammetry, demonstrated the potential stability of oxidized forms, and also the increased electron-donating ability of the salalen ligand in comparison to the salen analogue. The electronic structure of the one-electron oxidized [2] + was studied in detail, and Cu K-edge X-ray Absorption Spectroscopy (XAS) measurements confirmed a Cu II-phenoxyl radical complex in solution. Resonance Raman (rR) and variable temperature 1H NMR studies, coupled with theoretical calculations, showed that [2 ] + is a triplet (S = 1) Cu II-phenoxyl radical species, with localization of the radical on the more electron-rich aminophenoxide. Attempted isolation of X-ray quality crystals of [2 ] + afforded [2H] +, with a protonated phenol bonded to Cu II, and an additional H-bonding interaction with the SbF 6 counterion. Stoichiometric reaction of dilute solutions of [2 ] + with benzyl alcohol showed that the complex reacts in a similar manner as the oxidized Cu II-salen analogue, and does not exhibit a substrate-binding pre-equilibriummore » as observed for the oxidized bis-aminophenoxide Cu II-salan derivative.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6]
  1. Stanford Univ., Stanford, CA (United States); Univ. of the Fraser Valley, Abbotsford, BC (Canada)
  2. California State Univ., Chico, CA (United States)
  3. Ibaraki Univ., Mito (Japan)
  4. The Univ. of Minnesota, Minneapolis, MN (United States)
  5. Simon Fraser Univ., Burnaby, BC (Canada)
  6. Stanford Univ., Stanford, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1469090
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganica Chimica Acta
Additional Journal Information:
Journal Volume: 481; Journal Issue: C; Journal ID: ISSN 0020-1693
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Chiang, Linus, Wasinger, Erik C., Shimazaki, Yuichi, Young, Jr., Victor, Storr, Tim, and Stack, T. Daniel P.. Electronic structure and reactivity studies of a nonsymmetric one-electron oxidized CuII bis-phenoxide complex. United States: N. p., 2017. Web. doi:10.1016/j.ica.2017.09.042.
Chiang, Linus, Wasinger, Erik C., Shimazaki, Yuichi, Young, Jr., Victor, Storr, Tim, & Stack, T. Daniel P.. Electronic structure and reactivity studies of a nonsymmetric one-electron oxidized CuII bis-phenoxide complex. United States. doi:10.1016/j.ica.2017.09.042.
Chiang, Linus, Wasinger, Erik C., Shimazaki, Yuichi, Young, Jr., Victor, Storr, Tim, and Stack, T. Daniel P.. Mon . "Electronic structure and reactivity studies of a nonsymmetric one-electron oxidized CuII bis-phenoxide complex". United States. doi:10.1016/j.ica.2017.09.042. https://www.osti.gov/servlets/purl/1469090.
@article{osti_1469090,
title = {Electronic structure and reactivity studies of a nonsymmetric one-electron oxidized CuII bis-phenoxide complex},
author = {Chiang, Linus and Wasinger, Erik C. and Shimazaki, Yuichi and Young, Jr., Victor and Storr, Tim and Stack, T. Daniel P.},
abstractNote = {Here, the tetradentate mixed imino/amino phenoxide ligand (N-(3,5-di-tert-butylsalicylidene)-N'-(2-hydroxyl-3,5-di-tert-butylbenzyl))-trans-1,2-cyclohexanediamine (salalen) was complexed with CuII, and the resulting Cu complex (2) was characterized by a number of experimental techniques and theoretical calculations. Two quasi-reversible redox processes for 2, as observed by cyclic voltammetry, demonstrated the potential stability of oxidized forms, and also the increased electron-donating ability of the salalen ligand in comparison to the salen analogue. The electronic structure of the one-electron oxidized [2]+ was studied in detail, and Cu K-edge X-ray Absorption Spectroscopy (XAS) measurements confirmed a CuII-phenoxyl radical complex in solution. Resonance Raman (rR) and variable temperature 1H NMR studies, coupled with theoretical calculations, showed that [2•]+ is a triplet (S = 1) CuII-phenoxyl radical species, with localization of the radical on the more electron-rich aminophenoxide. Attempted isolation of X-ray quality crystals of [2•]+ afforded [2H]+, with a protonated phenol bonded to CuII, and an additional H-bonding interaction with the SbF6– counterion. Stoichiometric reaction of dilute solutions of [2•]+ with benzyl alcohol showed that the complex reacts in a similar manner as the oxidized CuII-salen analogue, and does not exhibit a substrate-binding pre-equilibrium as observed for the oxidized bis-aminophenoxide CuII-salan derivative.},
doi = {10.1016/j.ica.2017.09.042},
journal = {Inorganica Chimica Acta},
number = C,
volume = 481,
place = {United States},
year = {Mon Sep 18 00:00:00 EDT 2017},
month = {Mon Sep 18 00:00:00 EDT 2017}
}

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