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doi.org/10.1002/ejic.202000727
EurJIC
European Journal of Inorganic Chemistry
under reduced pressure and the solid was dissolved in Et O, filtered
through Celite and the solvent was evaporated under reduced pres-
sure yielding 305 mg (95 %) of complex 7 as a crystalline yellow
Magnetic measurements. The magnetic data were acquired on a
Quantum-Design MPMS-XL SQUID magnetometer. Susceptibility
data were acquired in a static field of 1.0 K Oe. Magnetization data
2
solid. Single crystals suitable for X-ray diffraction analysis were pre- were obtained with selected fields from 0 to 50 K Oe at T = 2–10 K
1
pared by slow diffusion of Et O into a DCM solution of 7 at 5 °C H
in 1K intervals. The polycrystalline samples were measured on a
2
NMR (500 MHz, C D ) δ 9.68–9.64 (m, 1H), 7.04–7.01 (m, 2H), 6.95– compacted powder sample in a polycarbonate capsule. Data were
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6
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2
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1
.92 (m, 1H), 6.86 (d, J = 7.8 Hz, 1H), 6.77 (td, J = 7.7, 1.6 Hz, 1H),
.34–6.29 (m, 1H), 2.79 (d, J = 9.1 Hz, 2H), 2.56 (d, J = 13.5 Hz, 2H), the sample moment from the sample holder and sample was cor-
corrected empirically for TIP and the diamagnetic contribution to
.11 (td, J = 12.1, 3.2 Hz, 2H), 1.84 (qdd, J = 12.9, 5.6, 3.8 Hz, 2H),
.69 (d, J = 14.4 Hz, 2H), 1.61 (d, J = 13.0 Hz, 2H), 1.56–1.46 (m, 6H),
rected through background measurements and Pascal constants,
respectively.
1
3
1
.29–1.17 (m, 2H), 1.12–1.00 (m, 4H). C{ H} NMR (126 MHz, C D )
6
6
EPR spectroscopy. The EPR spectra were recorded with a Bruker
Elexsys E500 equipped with a Bruker ER 4116 DM dual-mode cavity,
an EIP 538B frequency counter, and an ER035M NMR Gauss meter.
Data were recorded at X-band frequencies (ν≈9.63 GHz). The spec-
tra were simulated using home-written software considering an
electronic spin of 1/2 and taking into account only the experimen-
tally resolvable interactions with the nuclear spin of one bromide
δ = 165.9 (d, J = 29.7 Hz), 163.6 (d, J = 2.1 Hz), 151.9 (s), 149.9 (d,
J = 18.6 Hz), 147.6 (d, J = 0.6 Hz), 138.2 (s), 125.6 (d, J = 18.1 Hz),
1
25.0 (s), 122.5 (d, J = 2.0 Hz), 120.9 (d, J = 1.6 Hz), 117.1 (s), 35.4
(
(
d, J = 33.1 Hz), 34.5 (d, J = 23.0 Hz), 28.8 (dd, J = 14.2, 2.2 Hz), 27.1
dd, J = 23.3, 11.4 Hz), 26.4 (d, J = 1.2 Hz). P{ H} NMR (202 MHz,
3
1
1
C D ) δ = 68.88 (s). Found (calcd. for. C H BrNPNi): C, 56.81 (57.30);
H, 6.13 (6.21); N, 2.70 (2.78).
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24 31
(I = 3/2). No distinction was made between the naturally occurring
bromine isotopes. Simulation parameters are given in the Figure
legends.
Synthesis of [NCN]Ni-Br (9). To a solution of the (NCN)H ligand 8
(
441 mg, 1.9 mmol) in 35 mL THF, (DME)NiBr (586 mg, 1.9 mmol)
2
was added inside the glovebox. Then Et N (2.6 mL, 19 mmol) was
3
Electrochemical measurements. Cyclic voltammetry measure-
ments were carried out at room temperature using a PalmSens po-
tentiostat (–2 to +2 V for potential windows) and a 3mm glassy
carbon electrode as working electrode, a Ag/AgCl leakless reference
added to the reaction mixture. The flask was sealed and the reac-
tion mixture stirred overnight at 75 °C. THF and all volatiles were
removed under reduced pressure and the solid was dissolved in
DCM, washed with water, and the organic layer was dried with an-
electrode, and a platinum wire as a counter electrode. A 1 m
M solu-
hydrous Na SO . The solvent was evaporated under reduced pres-
2
4
tion of complex 6 in acetonitrile containing 0.1 (Bu N)PF as elec-
M
4
6
sure yielding 463 mg (65.8 %) of a reddish-yellow solid. Single crys-
trolyte was used and 0.1 V/s scan rate was applied. Ferrocene was
used for standardization.
tals suitable for X-ray diffraction analysis were prepared by slow
1
diffusion of Et O into a DCM solution of 9 at 5 °C. H NMR (400 MHz,
2
Crystallography. Data collection and refinement was performed as
DMSO) δ 8.89 (d, J = 5.6 Hz, 2H), 8.07 (td, J = 7.7, 1.4 Hz, 2H), 7.93
[
22]
previously reported.
All data is available in CIF format (CCDC
(
(
(
(
(
d, J = 7.7 Hz, 2H), 7.57 (d, J = 7.6 Hz, 2H), 7.39–7.30 (m, 2H), 7.23
13
1
t, J = 7.6 Hz, 1H). C{ H} NMR (101 MHz, C D ) δ = 168.8 (s), 162.1
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s), 154.1 (s), 144.1 (s), 140.3 (s), 125.3 (s), 123.5 (s), 123.2 (s), 119.0
s). Anal. Found (calcd. for. C H BrN Ni): C, 51.80 (51.96); H, 3.13
crystallographic data for this paper. These data are provided free of
charge by the joint Cambridge Crystallographic Data Centre and
Fachinformationszentrum Karlsruhe Access Structures service
www.ccdc.cam.ac.uk/structures.
1
6
11
2
3.00); N, 7.49 (7.57).
Synthesis of [tBuPCNPy]Ni(III)Br2 (10). To a solution of 18.04 mg
0.04 mmol) of 6 in 4 mL of DCM was added 8.93 mg (0.04 mmol)
of anhydrous CuBr immediately forming a deep red colored solu-
(
2
tion with concomitant formation of a precipitate. The reaction was Acknowledgments
left stirring for 1 h. Filtration over Celite and evaporation of the
solvent under reduced pressure yielded 20.8 mg (98 %) of the prod-
uct as dark crystalline solid. The complex is NMR silent. Anal. Found
Financial support from the Swedish Research Council, the Knut
and Alice Wallenberg Foundation and the Royal Physiographic
Society in Lund is gratefully acknowledged.
(
(
calcd. for. C H Br NPNi): C, 45.52 (45.25); H, 5.27 (5.13); N, 2.61
2.64).
20 27 2
Synthesis of [tBuPCNPy]Ni-Et (11). In a J. Young NMR tube, 20 μL
Keywords: Cross-coupling · Homogeneous catalysis ·
M
in THF) of EtMgCl was added to 9.0 mg Nickel · Pincer ligands · Paramagnetic complexes
(0.02 mmol, 2.0
(
0.02 mmol) of complex 6 in 0.5 mL of C D inside the glove box.
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The yellow colour of the solution turned immediately into red
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3
1
1
1
(wine). The reaction was monitored by P{ H} and H NMR spectro-
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[
[
3] M. E. van der Boom, D. Milstein, Chem. Rev. 2003, 103, 1759–1792.
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1
at –20 °C. H NMR (500 MHz, C D ) δ 8.64 (d, J = 5.6 Hz, 1H), 7.24
6
6
(d, J = 7.1 Hz, 1H), 7.15–7.08 (m, 3H), 6.93 (td, J = 7.9, 1.6 Hz, 1H),
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6] G. van Koten, D. Milstein (Eds.), Organometallic pincer chemistry. Top.
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6
.48 (d, J = 6.5 Hz, 1H), 3.19 (d, J = 8.5 Hz, 2H), 1.60 (td, J = 7.8,
.3 Hz, 3H), 1.28 (d, J = 12.3 Hz, 18H), 0.70 (qd, J = 7.8, 4.4 Hz, 2H).
1
13
1
[7] K. J. Szabó, O. F. Wendt (Eds.), Pincer and Pincer-Type Complexes; Wiley-
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[
[
C{ H} NMR (101 MHz, C D ) δ = 167.5 (d, J = 33.8 Hz), 167.4, 148.4,
6
6
1
3
1
38.9, 137.2, 124.2, 124.0, 123.6, 121.4 (d, J = 8.1 Hz), 119.7, 117.2,
9.6 (d, J = 29.2 Hz), 35.0 (d, J = 25.5 Hz), 29.6 (d, J = 15.1 Hz), 25.0,
8] G. Bauer, X. Hu, Inorg. Chem. Front. 2016, 3, 741–765.
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31
1
4.2. P{ H} NMR (202 MHz, C D ) δ = 85.35 (s). Due to thermal
6
6
decomposition the complex failed to give an accurate elemental
analysis.
[10] M. Gandelman, A. Vigalok, L. J. W. Shimon, D. Milstein, Organometallics
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Eur. J. Inorg. Chem. 2020, 4270–4277
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