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Abstract Understanding the electronic structures of high‐valent metal complexes aids the advancement of metal‐catalyzed cross coupling methodologies. A prototypical complex with formally high valency is [Cu(CF3)4]−(1), which has a formal Cu(III) oxidation state but whose physical analysis has led some to a Cu(I) assignment in an inverted ligand field model. Recent examinations of1by X‐ray spectroscopies have led previous authors to contradictory conclusions, motivating the re‐examination of its X‐ray absorption profile here by a complementary method, resonant diffraction anomalous fine structure (DAFS). From analysis of DAFS measurements for a series of seven mononuclear Cu complexes including1, here it is shown that there is a systematic trifluoromethyl effect on X‐ray absorption that blue shifts the resonant Cu K‐edge energy by 2–3 eV per CF3, completely accounting for observed changes in DAFS profiles between formally Cu(III) complexes like1and formally Cu(I) complexes like (Ph3P)3CuCF3(3). Thus, in agreement with the inverted ligand field model, the data presented herein imply that1is best described as containing a Cu(I) ion with dncount approaching 10.
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Mononuclear and Dinuclear Copper Complexes of Tridentate Redox‐active Ligands with Tunable H‐bonding Donors: Structure, Spectroscopy and H + /e − Reactivity
Abstract In this research article, we describe the synthesis and characterization of mononuclear and dinuclear Cu complexes bound by a family of tridentate redox‐active ligands with tunable H‐bonding donors. The mononuclear Cu‐anion complexes were oxidized to the corresponding “high‐valent” intermediates by oxidation of the redox‐active ligand. These species were capable of oxidizing phenols with weak O−H bonds via H‐atom abstraction. Thermodynamic analysis of the H‐atom abstractions, which included reduction potential measurements, pKadetermination and kinetic studies, revealed that modification of the anion coordinated to the Cu and changes in the H‐bonding donor did not lead to major differences in the reactivity of the “high‐valent” CuY complexes (Y: hydroxide, phenolate and acetate), which indicated that the tridentate ligand scaffold acts as the H+and e−acceptor.
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- Award ID(s):
- 1941220
- PAR ID:
- 10227932
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – An Asian Journal
- Volume:
- 16
- Issue:
- 12
- ISSN:
- 1861-4728
- Format(s):
- Medium: X Size: p. 1608-1618
- Size(s):
- p. 1608-1618
- Sponsoring Org:
- National Science Foundation
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