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10.1002/chem.201704049
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CCDC 1561909 (1) contain the supplementary crystallographic data for
this paper. These data are provided free of charge by The Cambridge
Crystallographic Data Centre.
Scheme 2. Generalization to
a copper complex bearing
a
single redox
source 3. Reaction conditions for TEMPO–
and compounds 6 and 7 are identical to optimized conditions from Tables
and 2, and scheme 1 respectively. Catalyst loading: 20 mol%.
a
+
b
+
equivalent. CF
CF
3 3
source 2, CF
3
Acknowledgements
1
The authors thank UPMC, CNRS, IR-RPE CNRS FR3443
RENARD network (CW X-band EPR with Dr. J.-L. Cantin, INSP
UMR CNRS 7588, UPMC and X-band EPR in Lille). Sorbonne
Universités is acknowledged for an Emergence Sorbonne
Universités grant (MDEM and KC). Geoffrey Gontard and Lise-
Marie Chamoreau are acknowledged for XRD analysis and
Omar Khaled for mass spectrometry. The authors gratefully
acknowledge the support of this work by the COST Action 27
CM1305 ECOSTBio (Explicit Control Over Spin-States in
Technology and Biochemistry).
The UV-vis profiles of the TEMPO-trapping reactions (Figure 4,
red and black spectra) were a close match to the UV-vis
spectrum recorded upon independent oxidation of complex 8
with
one
equivalent
of
[Fc][PF
6
]
(ferrocenium
hexafluorophosphate, green spectrum) thus evidencing ligand-
!
based SET from complex 8 for the formation of CF
3
radicals.
The EPR spectra of complex 8 before and after oxidation were
recorded (SI, figure S12). As could be expected from the
antiferromagnetic coupling between the ligand radical and the
II
Cu center (S=0 ground state), complex 8 is EPR silent (Figure
1
9
+
S12 red trace). After reaction with the CF
presence of TEMPO, a strong axial signal with a g// of 2.26 and
// of 152G (Figure S12 black trace), typical of a Cu-centered
3
source in the
!
Keywords: nickel • redox-active ligand • CF
3
radicals • single
electron transfer
A
II
S=1/2 spin (ie Cu ) center is obtained, presumably resulting from
the one electron oxidation of the ligand to the diamagnetic LBQ
form. These results show that a “single redox-equivalent” ligand
is enough to promote the reactivity.
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+
Figure 4. UV-vis spectra for TEMPO-trapping experiments of CF
complex 8.
3
source with
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promoting radical generation through single-electron transfer
+
with an electrophilic CF
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Experimental Section
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