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Title: Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes

Abstract

The geometric and electronic structure of an oxidized Cu complex ([CuSal](+); Sal = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV-vis-NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal](+) (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal](+), affording exclusively a Cu(III) species in the solid state (4-300 K). Variable-temperature solution studies suggest that [CuSal](+) exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal(*)](+) (S = 1) and the high-valent metal form [Cu(III)Sal](+) (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine-bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSal(red)](+) (Sal(red) = N,N'-bis(3,5-di- tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)-ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affectmore » the locus of oxidation in Cu-bis-phenoxide complexes.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
953575
Report Number(s):
SLAC-REPRINT-2009-308
Journal ID: ISSN 0002-7863; JACSAT; TRN: US201002%%1403
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
J. Am. Chem. Soc 130:15448,2008
Additional Journal Information:
Journal Volume: 130; Journal Issue: 46; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; COMPLEXES; COORDINATION NUMBER; COPPER; COPPER COMPLEXES; CRYSTALLOGRAPHY; DENSITY; ELECTROCHEMISTRY; ELECTRONIC STRUCTURE; EQUILIBRIUM; FUNCTIONALS; INFORMATION; LIGANDS; MAGNETIC SUSCEPTIBILITY; METALS; OXIDATION; RAMAN SPECTROSCOPY; RESONANCE; SOLIDS; SOLUTIONS; SPECTROSCOPY; SPIN; VALENCE; VARIATIONS; Other,OTHER, CHEM

Citation Formats

Storr, T, Verma, P, Pratt, R C, Wasinger, E C, Shimazaki, Y, and Stack, T D.P. Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes. United States: N. p., 2009. Web.
Storr, T, Verma, P, Pratt, R C, Wasinger, E C, Shimazaki, Y, & Stack, T D.P. Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes. United States.
Storr, T, Verma, P, Pratt, R C, Wasinger, E C, Shimazaki, Y, and Stack, T D.P. Tue . "Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes". United States.
@article{osti_953575,
title = {Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes},
author = {Storr, T and Verma, P and Pratt, R C and Wasinger, E C and Shimazaki, Y and Stack, T D.P.},
abstractNote = {The geometric and electronic structure of an oxidized Cu complex ([CuSal](+); Sal = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV-vis-NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal](+) (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal](+), affording exclusively a Cu(III) species in the solid state (4-300 K). Variable-temperature solution studies suggest that [CuSal](+) exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal(*)](+) (S = 1) and the high-valent metal form [Cu(III)Sal](+) (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine-bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSal(red)](+) (Sal(red) = N,N'-bis(3,5-di- tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)-ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu-bis-phenoxide complexes.},
doi = {},
journal = {J. Am. Chem. Soc 130:15448,2008},
issn = {0002-7863},
number = 46,
volume = 130,
place = {United States},
year = {2009},
month = {5}
}