Organometallics
Article
sealed with a cap containing a PTFE septum, removed from the
glovebox, and placed in a temperature-controlled aluminum heating
block set to 110 °C with magnetic stirring. At the designated time, the
reaction vial was removed from the heating block and left to cool to
ambient temperature, followed by addition of dodecane internal
standard (0.12 mmol, 1.0 equiv) to the reaction mixture, which was
subsequently analyzed by use of GC methods following Workup
Method A. The product distribution observed when this method was
used (<5% unreacted ArCl, 71% ArNH , 11% Ar NH) is similar to
Synthesis of L16. In a nitrogen-filled glovebox, 1 (0.400 g, 1.08
mmol, 1.0 equiv) and diethyl ether (ca. 6 mL) were combined in a 4
dram vial along with a magnetic stir bar. The vial was sealed and then
cooled to −33 °C in the glovebox freezer. This vial was then removed
from the freezer, and a 2.5 M hexanes solution of cold (−33 °C) n-
butyllithium (0.517 mL, 1.3 mmol, 1.2 equiv) was added dropwise
under the influence of magnetic stirring, resulting in a yellowish
orange solution. This mixture was stirred for 30 min at ambient
temperature. At this time, a solution of dimesitylphosphorus chloride
2
2
(
395.0 mg, 1.3 mmol, 1.2 equiv) in diethyl ether (ca. 6 mL) was
that observed for analogous reactions employing (L1)NiCl /(o-
2
added, resulting in an orange solution. This mixture was stirred at
ambient temperature for 20 h. On the benchtop, the reaction mixture
was diluted with CH Cl (ca. 10 mL) and filtered over Celite, with
tolyl)MgCl catalyst mixtures (GP2) (<5% unreacted ArCl, 81%
ArNH , 8% Ar NH).
2
2
General Procedure for Monitoring the Reaction Progress
2
2
CH Cl as eluent (ca. 20 mL). The eluent was collected, and the
for the Cross-Coupling of Ammonia and 4-Chlorobiphenyl
2
2
Using (L)NiCl /(o-tolyl)MgCl Mixtures (GP4). Individual reactions
solvent was removed via rotary evaporation. The resulting yellow oil
2
was purified by flash chromatography (SiO ), with 3% ethyl acetate/
were set up for each time interval. In a nitrogen-filled glovebox,
precatalyst (0.006 mmol, 5 mol %), 4-chlorobiphenyl (2; 22.6 mg,
2
hexanes as eluent. The resulting beige waxy solid was recrystallized in
cold pentane (0 °C) overnight, which following filtration afforded
0.12 mmol, 1.0 equiv), sodium tert-butoxide (23.1 mg, 0.24 mmol, 2.0
1
L16 as a white crystalline solid (260.0 mg, 43% yield). H NMR
equiv), o-tolylmagnesium chloride as a 1.0 M solution in THF (24.0
μL, 0.024 mmol, 0.2 equiv), and ammonia as a 0.5 M solution in 1,4-
dioxane (2.4 mL, 1.2 mmol, 10.0 equiv) were placed in a screw-
capped vial containing a magnetic stir bar. The vial was sealed with a
cap containing a PTFE septum, removed from the glovebox, and
placed in a temperature-controlled aluminum heating block set to 110
(
CDCl , 500.1 MHz): δ 8.27 (m, 1H, ArH), 7.30−7.27 (m, 1H,
3
ArH), 7.17−7.13 (m, 2H, ArH), 6.90 (d, J = 2.0 Hz, 2H, ArH), 6.76
d, J = 2.5 Hz, 2H, ArH), 2.31 (s, 3H, Me), 2.27 (s, 3H, Me), 2.16−
.13 (m, 7H, Me/CgP), 2.04−2.02 (m, 7H, Me/CgP), 1.89 (m, 1H,
CgP), 1.59−1.55 (m, 4H, CgP), 1.48 (s, 3H, Me), 1.39 (s, 3H, Me),
(
2
1
3
1
1
.38 (d, J = 12.0 Hz, 3H, Me). C{ H} NMR (CDCl , 125.8 MHz):
3
°C with magnetic stirring. At the designated time, the reaction vial
δ 148.1 (dd, J = 33.9, 15.1 Hz, ArC), 144.5 (d, J = 16.3 Hz, ArC),
was removed from the heating block and left to cool to ambient
temperature, followed by addition of dodecane internal standard (0.12
mmol, 1.0 equiv) to the reaction mixture, which was subsequently
analyzed by use of GC methods following Workup Method A.
General Procedure for the Cross-Coupling of 4-Amino-
1
1
1
3
42.3 (d, J = 16.3 Hz, ArC), 140.7−140.2 (m, ArC), 138.8 (ArC),
37.3 (ArC), 134.1 (ArC), 133.4 (d, J = 7.5 Hz, ArC), 131.8 (d, J =
8.9 Hz, ArC), 130.8 (dd, J = 20.7, 11.3 Hz, ArC), 130.2 (dd, J =
5.2, 3.8 Hz, ArC), 129.4 (ArC), 128.1 (ArC), 97.0 (CgP), 96.2
(
2
1
CgP), 74.7−74.3 (m, CgP), 46.2 (d, J = 20.1 Hz, CgP), 36.5 (CgP),
biphenyl and 4-Chlorobiphenyl Using (L)NiCl /(o-tolyl)MgCl
2
9.1 (dd, J = 18.9, 7.5 Hz, CgP), 28.4 (Me), 27.9 (Me), 26.8 (d, J =
1.3 Hz, Me), 23.6 (dd, J = 41.5, 16.3 Hz, Me), 21.2 (d, J = 10.0 Hz,
Mixtures (GP5). In a nitrogen-filled glovebox, precatalyst (0.006
mmol, 5 mol %), 4-chlorobiphenyl (2; 22.6 mg, 0.12 mmol, 1.0
equiv), sodium tert-butoxide (23.1 mg, 0.24 mmol, 2.0 equiv), o-
tolylmagnesium chloride as a 1.0 M solution in THF (24.0 μL, 0.024
mmol, 0.2 equiv), and 4-aminobiphenyl (20.3 mg, 0.12 mmol, 1.0
equiv) were placed in a screw-capped vial containing a magnetic stir
bar, followed by the addition of 2.4 mL of 1,4-dioxane ([ArCl] = 0.05
M). The vial was sealed with a cap containing a PTFE septum,
removed from the glovebox, and placed in a temperature-controlled
aluminum heating block set to 110 °C for 2 h with magnetic stirring.
The reaction vial was then removed from the heating block and left to
cool to ambient temperature, followed by addition of dodecane
internal standard (0.12 mmol, 1.0 equiv) to the reaction mixture,
which was subsequently analyzed by use of GC methods following
Workup Method A.
3
1
1
Me). P{ H} (202.5 MHz, CDCl ): δ −24.9 (d, J = 158 Hz, 1P),
3
PP
−
36.8 (d, JPP = 159 Hz, 1P). HRMS-ESI (m/z): calcd for C H O P
34 43 3 2
[
M + H], 561.2687; found, 561.2682. A single crystal suitable for X-
ray diffraction was obtained by slow evaporation of L16 in cold (0
°
C) hexanes.
Synthesis of (L15)NiCl . In a nitrogen-filled glovebox, a 4 dram
2
vial was charged with NiCl (dme) (219.6 mg, 0.999 mmol, 1.0 equiv)
2
and L15 (500.0 mg, 1.05 mmol 1.05 equiv). To these solids was
added THF (ca. 10 mL), affording a cloudy brown mixture. A
magnetic stir bar was added, the vial was sealed, and stirring was
initiated. After several minutes, a red precipitate formed. The resulting
mixture was stirred at ambient temperature for 2 h, after which time
the vial was removed from the glovebox and pentane (5 mL) was
added. The precipitated red solid was collected on a glass filter frit,
and the retained solid was washed with cold (∼0 °C) pentane (3 × 3
mL). The collected solid product was then washed off of the frit by
passing CH Cl (ca. 50 mL) through the frit, followed by evaporation
Workup Method A: Procedure for the Preparation of GC
Samples. Following GP1−GP5, the reaction mixture was diluted
using ethyl acetate and was passed through a Kimwipe filter
containing Celite and silica. The eluent was collected in a GC vial,
followed by analysis using calibrated GC methods.
2
2
of solvent from the intensely red eluent. The product was then dried
in vacuo to afford the desired complex as a crimson solid (520 mg,
General Procedure for Ligand Substitution Reactions
Involving L and Ni(cod)2 (Scheme 1). In a nitrogen-filled
glovebox, L1, L15, or L16 (0.019 mmol), and bis(cyclooctadiene)-
nickel(0) (5.2 mg, 0.019 mmol) were placed in a screw-capped vial
containing a magnetic stir bar, followed by the addition of 0.75 mL of
C D . The vial was sealed with a cap containing a PTFE septum and
1
8
6%). H NMR (500.1 MHz, CDCl ): δ 8.45 (d, J = 8.0 Hz, 1H,
3
ArH), 8.04 (d, J = 7.6 Hz, 2H, ArH), 7.64−7.61 (m, 3H, ArH), 7.56−
.54 (m, 2H, ArH), 7.51−7.48 (m, 2H, ArH), 7.45 (d, J = 7.1 Hz, 1H,
ArH), 7.41−7.36 (m, 3H, ArH), 4.19 (d, J = 13.6 Hz, 1H, CgP), 2.20
d, J = 13.9 Hz, 1H, CgP), 1.85 (d, J = 13.7 Hz, 2H, CgP), 1.61 (s,
7
(
13
1
6
6
3H, Me), 1.57 (s, 3H, Me), 1.52−1.51 (m, 6H, Me). C{ H} NMR
(
placed in a temperature-controlled aluminum heating block set to 80
C for 2 h with magnetic stirring. After the mixture was cooled to
125.8 MHz, CDCl ): δ 144.1 (ArC), 137.7 (ArC), 135.0 (ArC),
3
°
1
34.8 (ArC), 134.5 (ArC), 133.9 (ArC), 133.0 (ArC), 132.7 (ArC),
ambient temperature, the vial was brought into the glovebox and an
NMR sample was prepared. Analysis of the reaction mixture by use of
132.4 (ArC), 132.1 (ArC), 131.6 (ArC), 129.1 (ArC), 128.7 (ArC),
128.4 (ArC), 97.6 (CgP), 97.0 (CgP), 79.3 (CgP), 74.8 (CgP), 41.7
(CgP), 40.4 (CgP), 28.6 (Me), 27.8 (Me), 26.9 (Me), 25.7 (Me).
31
1
P{ H} NMR methods revealed partial conversion of L1 and the
3
3
1
1
1
appearance of two resonances at 46.1 and 38.4 ppm (JPP = 40.5 Hz),
which we tentatively assign to (L1)Ni(cod). For L15, analysis of the
P{ H} NMR (202.5 MHz, CDCl ): no observable signals in the
3
1
P{ H} NMR spectrum. Anal. Calcd for C H Cl NiO P : C, 55.49;
2
8
30
2
3 2
3
1
1
reaction mixture by use of P{ H} NMR methods revealed complete
consumption of L15 and the appearance of two resonances at 51.2
and 38.5 ppm (JPP = 40.5 Hz), which we tentatively assign to
H, 4.99; N, 0. Found: C, 55.16; H, 5.21; N, <0.3.
Synthesis of (L16)NiCl . In a nitrogen-filled glovebox, a 4 dram
2
vial containing a magnetic stir bar was charged with NiCl (dme)
2
(
L15)Ni(cod). For L16, only free ligand was detected upon analysis
(48.9 mg, 0.223 mmol, 1.0 equiv) and L16 (150.0 mg, 0.268 mmol,
1.2 equiv). The solid mixture was dissolved in THF (ca. 2 mL),
3
1
1
of the reaction mixture by use of P{ H} NMR methods.
G
Organometallics XXXX, XXX, XXX−XXX