Organometallics
Article
Bu -4-Me-C H OH (BHT), t-BuOK, N-bromosuccinimide, and
(57 mg, 33%). Recrystallization from warm CH Cl gave orange
2
6
2
2
2
morpholine (Aldrich); NEt3 and H O2 (Acros); c-C H NH
crystals after standing overnight. Gradual, spontaneous sublimation of
iodine circumvented an accurate elemental analysis of this compound.
The 1H NMR and UV−vis spectra of this adduct were virtually
identical with the corresponding spectra of 1 (see Figures S1 and S31
in the Supporting Information).
2
6
11
2
(
American Chemicals). NiBr (NCiPr) was synthesized according to
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20
a literature procedure.
The NMR spectra were recorded on the following spectrometers:
1
1
Bruker AV400rg ( H at 400 MHz) and Bruker ARX400 ( H at 400
MHz and 13C{ H} at 100.56 MHz). Chemical shift values are reported
1
N
C
N′
{
κ ,κ ,κ -2,6-(pyrazole) -C H }Ni(BHT) (3). A dry Schlenk flask
1
2 6 3
in ppm (δ) and referenced internally to the residual solvent signals ( H
purged with N was charged with 1 (0.200 g, 0.575 mmol), BHT
and 13C: 7.26 and 77.16 ppm for CDCl ; 7.16 and 128.06 ppm for
2
3
(
0.127 g, 0,575 mmol), and THF (30 mL). NaH (0.022 g, 0.96 mmol)
C D ). Coupling constants are reported in Hz. The elemental analyses
6
6
was then added slowly to this mixture against a flow of N . The final
2
́
were performed by the Laboratoire d’Analyze Elem
ment de chimie, Universite de Montreal.
5-Methoxy-1,3-phenylene)bis(1H-pyrazole) (b). A dried
́ ́
entaire, Departe-
mixture was stirred at room temperature for 20 h. The resulting orange
solution was evaporated under vacuum and the yellow residue
́
́
(
extracted with dry Et O (5 × 10 mL). Evaporation to dryness gave a
2
Schlenk flask was charged with 3,5-dibromo-1-methoxybenzene (1.13
1
bright orange powder (0.280 g, 78% yield). H NMR (C D ): δ 7.39
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6
g, 4.25 mmol), pyrazole (0.868 g, 12.8 mmol), K CO (3.52 g, 25.5
2
3
(
6
2H, s, H10), 6.88 (2H, d, JHH = 2.1, H5), 6.67 (1H, t, JHH = 7.8, H4),
mmol), CuI (0.032 mg, 0.170 mmol), and N,N-dimethylglycine (0.029
.57 (2H, d, JHH = 2.4, H7), 6.05 (2H, d, JHH = 7.8, H3), 5.47 (2H, t,
g, 0.286 mmol). The system was purged three times with N , and 15
13
2
JHH = 2.4, H6), 2.63 (3H, s, H12), 2.19 (18H, s, H14). C NMR
mL of DMSO was added. This mixture was then heated at 130 °C for
(
1
C D ): δ 167.6 (1C, s, C8), 143.97 (2C, s, C2), 141.18 (2C, s, C5),
40.64 (2C, s, C9), 139.88 (1C, s, C1), 126.30 (2C, s, C10), 124.77
6 6
96 h and then cooled to room temperature. Water (30 mL) and ethyl
acetate (30 mL) were then added to the final mixture, and the
resulting mixture was partitioned. The organic layer was extracted with
ethyl acetate (3 × 15 mL) and washed with brine. The ethyl acetate
fractions were combined and evaporated next, and the residue was
purified by column chromatography (silica gel; eluent 20/80 to 40/60
mixtures of ethyl acetate and hexanes). Evaporation of the combined
(
1C, s, C4), 124.36 (2C, s, C7), 121.82 (1C, s, C11), 107.23 (2C, s,
C6), 106.91 (2C, s, C3), 36.22 (2C, s, C13), 32.37 (6C, s, C14), 22.09
(
1
1C, s, C12). Anal. Calcd for C H N NiO (487.26): C, 66.55; N,
1.50; H, 6.62. Found: C, 66.16; N, 11.30; H, 6.58.
27 32 4
4
-Bromo-2,6-bis(1H-pyrazol-1-yl)phenol and 2,6-Bis(1H-pyr-
azol-1-yl)phenol. A Schlenk flask was charged with 1 (0,050 g, 0,144
1
fractions gave the final product as an off-white solid (0.171 g, 46%). H
mmol), CH Cl (30 mL), and H O (1 mL of 30% solution in water,
2
2
2
2
NMR (CDCl , 400 MHz), δ 7.99 (2H, d, J = 2.5, H5), 7.74 (2H, d,
3
HH
9.79 mmol), and the mixture was stirred for 18 h. The initially yellow
mixture changed to deep purple over 20 min, but this color faded
JHH = 1.6, H7), 7.64 (1H, t, JHH = 1.9, H1), 7.22 (2H, d, J = 1.9,
HH
H3), 6.49 (2H, t, JHH = 1.9, H6), 3.93 (3H, s, H8). 13C NMR
gradually such that the final mixture was yellowish. Addition of H O
2
(
CDCl ): δ 161.42 (1C, s, C4), 142.01 (2C, s, C2), 141.47 (2C, s,
3
(20 mL) followed by extraction with CH Cl (3 × 20 mL) and
2
2
C7), 127.19 (2C, s, C5), 108.13 (2C, s, C6), 102.98 (2C, s, C3),
02.23 (1C, s, C1), 56.02 (1C, s, C8). MS: m/z 240; the mass
spectrum is shown in the Supporting Information (Figure S23).
evaporation of the combined organic layers gave an oily residue which
was purified by column chromatography (silica; eluent CHCl3).
Evaporation of the first and second fractions gave the minor and major
components of the product mixture, respectively, as white powders (6
mg, 7%; 22 mg, 32%).
1
N
C
N′
{
κ ,κ ,κ -2,6-(pyrazole) -C H }NiBr (1). An oven-dried Schlenk
2 6 3
was taken inside the glovebox and charged with NiBr (NC(i-Pr))
2
(
1.64 g, 5.71 mmol), ligand a (1.00 g, 4.76 mmol), and NEt (0.927
Characterization Data for 4-Bromo-2,6-bis(1H-pyrazol-1-yl)-
3
1
phenol. H NMR (CDCl ): δ 12.43 (1H, s, H8), 8.21 (2H, d, J
mL, 0.673 g, 6.67 mmol). The reaction vessel was then taken out of
3
HH
=
2.4 H5), 7.75 (2H, d, H7), 7.71 (2H, s, H3), 6.52 (2H, t, J = 2.1,
the glovebox and 10 mL of m-xylene added against a flow of N . The
HH
2
13
H6). C NMR (CDCl ): δ 140.91 (1C, s, C1), 140.10 (2C, s, C7),
resulting mixture was refluxed for 36 h, cooled to room temperature,
and evaporated under reduced pressure. The resulting solid residue
was stirred with distilled water (3 × 20 mL, in air) and filtered on a
Buchner funnel, the solid residue being washed consecutively with 3 ×
3
1
29.75 (2C, s, C5), 129.09 (2C, s, C2), 121.84 (2C, s, C3), 111.05
+
(
1C, s, C4), 107.37 (2C, s, C6). LRMS: expected mass (M + H )
05.0, 307.0; found (M + H ) 305.1, 307.1.
+
3
Characterization Data for 2,6-Bis(1H-pyrazol-1-yl)phenol. 1H
2
0 mL each of cold MeOH and hexanes. The yellow powder thus
NMR (CDCl ): δ 12.32 (1H, s, H8), 8.20 (2H, d, J = 2.3 H5), 7.75
obtained was then extracted with THF, concentrated under reduced
pressure, and allowed to crystallize to give the target complex as
orange crystals (0.720 g, 44%). H NMR (CDCl ): δ 7.95 (2H, d, J
3
HH
(
6
1
2H, s, H7), 7.55 (2H, d, J = 8.1, H3), 7.01 (1H, t, JHH = 8.1, H4),
HH
.51 (2H, t, JHH = 2.0, H6). 1 C NMR (CDCl ): δ 142.07 (1C, s, C1),
3
1
3
3
HH
39.72 (2C, s, C7), 129.62 (2C, s, C5), 128.38 (2C, s, C2), 119.47
=
6
(
2.2, H5), 7.85 (2H, d, JHH = 2.7, H7), 7.18 (1H, t, JHH = 7.8, H4),
.85 (2H, d, JHH = 7.8, H3), 6.35 (2H, t, JHH = 2.4, H6). 13C NMR
DMSO-d ): δ 144.07 (2C, s, C5), 142.74 (2C, s, C2), 137.34 (1C, s,
(
2C, s, C3), 119.42 (1C, s, C4), 106.91 (2C, s, C6). LRMS: expected
+
+
mass (M + H ) 227.1, found (M + H ) 227.2.
2-Methoxy-1,3-phenylene)bis(1H-pyrazole). A round-bottom
6
(
C1), 128.58 (2C, d, C7), 126.87 (1C, s, C4), 108.66 (2C, s, C6),
08.57 (2C, s, C3). Anal. Calcd for C H BrN Ni (347.82): C, 41.44;
flask was charged with 1 (0.040 g, 0.116 mmol), MeOH (30 mL), and
distilled water (1.5 mL), and the mixture was stirred at reflux for 24 h.
The resulting pale yellow mixture was cooled to room temperature and
evaporated. The residue was extracted with diethyl ether (3 × 20 mL)
and evaporated, and the solid mixture was purified by column
chromatography (silica; eluent 20/80 ethyl acetate/hexane) to give
both the protonated ligand and the functionalized ligand (13 mg, 48%
1
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4
N, 16.11; H, 2.61. Found: C, 41.41; N, 16.16; H, 2.53.
N
C
N′
{
κ ,κ ,κ -2,6-bis(pyrazole),4-MeO-C H }NiBr (2). The above
6 2
procedure was followed using NiBr (NC(i-Pr)) (1.06 g, 3.68 mmol),
2
ligand b (0.632 g, 2.63 mmol), and NEt (0.513 mL, 0.373 g, 3.69
3
mmol) in xylene (10 mL). The target complex 2 was obtained as
1
orange crystals (0.235 mg, 24%). H NMR (CDCl ): δ 7.89 (2H, d,
1
3
yield). H NMR (CDCl , 400 MHz): δ 8.10 (2H, d, J = 2.4, H5),
3
HH
JHH = 2.0, H5), 7.81 (2H, d, JHH = 2.7, H7), 6.46 (2H, s, H3), 6.34
7
.75 (2H, d, JHH = 1.6, H7), 7.69 (2H, d, JHH = 8.0, H3), 7.32 (1H, t,
(
2H, t, JHH = 2.4, H6), 3.87 (3H, s, H8). 13C NMR (CDCl ): δ 159.82
13
3
JHH = 8.0, H4), 6.49 (2H, t, JHH = 2.0, H6), 3.28 (3H, s, H8).
C
(
1C, s, C4), 144.50 (2C, s, C5), 142.68 (2C, s, C2), 127.92 (1C, s,
NMR (CDCl ): δ 144.85 (1C, s, C1), 140.98 (2C, s, C7), 134.97 (2C,
3
C1), 125.59 (2C, s, C7), 107.85 (2C, s, C6), 94.76 (2C, s, C3), 56.19
s, C2), 131.28 (2C, s, C5), 125.09 (1C, s, C4), 124.18 (2C, s, C3),
(
1
1C, s, C8). Anal. Calcd for C H BrN Ni (377.85): C, 41.32; N,
4.83; H, 2.93. Found: C, 41.23; N, 14.78; H, 2.86.
12 9 4
1
07.40 (2C, s, C6), 60.94 (1C, s, C8). GC/MS: m/z 240.
2-Ethoxy-1,3-phenylene)bis(1H-pyrazole). A round-bottom
(
N
C
N′
{
κ ,κ ,κ -2,6-(pyrazole) -C H }NiBr·I , (1·I ). A CH Cl solution
2
flask was charged with 1 (0.150 g, 0.431 mmol) and 95% EtOH (40
mL), and the mixture was stirred for 5 h at reflux. The resulting pale
yellow solution was cooled to room temperature and then evaporated.
The solid residue was then purified by column chromatography on
silica with acetone as eluent. The combined fractions were evaporated
2
6
3
2
2
2
2
of I (0.073 g, 0.288 mmol, in 10 mL) was added dropwise to a THF
solution of 1 (0.100 g, 0.288 mmol, in 30 mL). The mixture turned
immediately from yellow to deep orange, and an orange powder
precipitated after 20 min. The final mixture was filtered after an
additional 2 h of stirring to give the crude product as an orange solid
1
to give the desired product as an oil (47 mg, 68% yield). H NMR
1
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Organometallics 2015, 34, 133−145