G. Cao et al. / Journal of Organometallic Chemistry 745-746 (2013) 158e165
159
Benzyl chloride (20 mmol) was added to the reaction mixture in
the presence of iodine catalyst. After the reaction finished (ca
1.5 h), the reaction mixture was cooled to room temperature, then
NHCOR
R1
N
R1
N
R1
N
R2
R2
Ar
N
R2
a
solution
of
2,6-(CH3)2C6H3eN]C(CH3)eC(CH3)]N-2,6-
N
N
(CH3)2C6H3 (1a, 20 mmol) in anhydrous ether (10 mL) was
injected slowly through a syringe. The mixture was allowed to stir
for 24 h at room temperature, and then the mixture was filtered.
The filtrate was carefully hydrolyzed with 5% aqueous NaOH so-
lution, and the organic layer was separated, dried over Na2SO4
and concentrated to give the crude product. The pure ligand was
recrystallized from ethanol to afford the white solid in 51% yield.
There are two isomers found in solution sate (the ratio is ca 1:1).
I
II
III
R3
R1
N
iPr
N
N
R1
N
HN R1
Ar
N
HN Ar
R2
iPr
Isomer 1: 1H NMR (300 MHz, CDCl3),
d (ppm): 7.52e7.50 (m, 2H,
This work
IV
V
AreH), 7.17e7.13 (m, 3H, AreH), 6.94e6.75 (m, 6H, AreH), 5.35 (s,
1H, NH), 3.71 (s, 2H, CH2Ph), 2.32 (s, 6H, CH3), 1.92 (s, 3H, CH3),
1.66 (s, 3H, CH3), 1.33 (s, 6H, CH3). 13C NMR (75 MHz, CDCl3),
Fig. 1. Types of N,N-bidentate ligands.
2. Experimental section
d
(ppm): 174.14 (C]N), 147.76, 144.65, 138.24, 133.90, 130.26,
128.63, 127.91, 126.61, 126.35, 124.76, 122.54, 65.80, 44.22, 24.91,
21.47, 18.08, 16.75. Isomer 2: 1H NMR (300 MHz, CDCl3),
(ppm):
2.1. Physical measurements and materials
d
7.52e7.50 (m, 2H, AreH), 7.17e7.13 (m, 3H, AreH), 6.94e6.75 (m,
6H, AreH), 5.35 (s, 1H, NH), 2.88 (s, 2H, CH2Ph), 2.32 (s, 6H, CH3),
1.92 (s, 3H, CH3), 1.66 (s, 3H, CH3), 1.24 (s, 6H, CH3). 13C NMR
2,6-Dimethylaniline and 2,6-diisopropylaniline were purchased
from Aldrich Chemical and were distilled under reduced pressure
before being used. Palladium chloride and trimethylaluminium
(1 M, hexane) was purchased from Aldrich Chemical. 2,3-
Butanedione and benzyl chloride was purchased from Guangzhou
Chemical Reagent Factory and was used as received. Toluene was
refluxed over metallic sodium for 24 h before being used. 2,6-
(CH3)2C6H3eN]C(CH3)eC(CH3)]Ne2,6-(CH3)2C6H3 (1a), 2,6-(iPr)2
C6H3eN]C(CH3)eC(CH3)]Ne2,6-(iPr)2C6H3 (1b), 2,6-(CH3)2C6H3e
N]C(CH3)eC(CH3)(CH3)eNHe2,6-(CH3)2C6H3 (L1) and 2,6-
(iPr)2C6H3eN]C(CH3)eC(CH3)eNHe2,6-(iPr)2C6H3 (L2) [45,46],
were prepared according to literature methods.
The NMR data of compounds were obtained on a Varian
Mercury-Plus 300 MHz spectrometer at ambient temperature, us-
ing CDCl3 as solvent and referenced versus TMS as standard.
Elemental analyses were determined with a Vario EL Series
Elemental Analyzer from Elementar. The X-ray diffraction data of
(75 MHz, CDCl3),
d (ppm): 174.14 (C]N), 147.76, 144.65, 138.24,
133.90, 130.26, 128.63, 127.91, 126.61, 126.35, 124.76, 122.54,
65.80, 44.22, 24.91, 21.47, 18.08, 16.75. Elemental analysis calcu-
lated for C27H32N2: C, 84.33; H, 8.39; N, 7.28. Found: C, 84.17; H,
8.45; N, 7.15.
2.2.2. Synthesis of 2,6-(iPr)2C6H3eN]C(CH3)eC(CH3)(CH2Ph)e
NHe2,6-(iPr)2C6H3 (L4)
Following the similar procedure, L4 was received as white
crystal in 54% yield. There are two isomers found in solution
sate (the ratio is ca 1:1). Isomer 1: 1H NMR (300 MHz, CDCl3),
d
(ppm): 7.64e7.61 (m, 2H, AreH), 7.21e7.13 (m, 3H, AreH),
7.07e7.02 (m, 4H, AreH), 6.95e6.93 (m, 2H, AreH), 5.30 (s, 1H,
NH), 3.67 (m, 2H, CH(CH3)2), 3.52 (s, 2H, CH2Ph), 2.75 (m, 2H,
CH(CH3)2), 1.58 (s, 3H, CH3), 1.16 (d, J ¼ 6.6 Hz, 12H, CH3), 1.10 (d,
J ¼ 6.6 Hz, 12H, CH3), 0.73 (s, 3H, CH3). 13C NMR (75 MHz, CDCl3),
single crystals were obtained with the
u-2q scan mode on a Bruker
SMART 1000 CCD diffractometer with graphite-monochromated
d
(ppm): 174.51(C]N), 147.11, 145.51, 140.27, 138.84, 136.65,
ꢀ
Mo K
a
radiation (
l
¼ 0.71073 A) at 173 K. The structure was
135.91, 129.79, 127.86, 126.34, 124.53, 123.30, 122.85, 65.93,
43.69, 28.99, 27.76, 25.53, 24.22, 23.77, 22.32, 17.37. Isomer 2: 1
NMR (300 MHz, CDCl3), (ppm): 7.64e7.61 (m, 2H, AreH), 7.21e
solved using direct methods, and further refinement with full-
matrix least squares on F2 was obtained with the SHELXTL pro-
gram package. All non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were introduced in calculated positions with
the displacement factors of the host carbon atoms.
H
d
7.13 (m, 3H, AreH), 7.07e7.02 (m, 4H, AreH), 6.95e6.93 (m, 2H,
AreH), 5.30 (s, 1H, NH), 3.67 (m, 2H, CH(CH3)2), 3.50 (s, 2H,
CH2Ph), 1.98 (m, 1H, CH(CH3)2), 1.58 (s, 3H, CH3), 1.16 (d,
J ¼ 6.6 Hz, 12H, CH3), 1.10 (d, J ¼ 6.6 Hz, 12H, CH3), 0.73 (s, 3H,
CH3). 13C NMR (75 MHz, CDCl3),
d (ppm): 174.51(C]N),
2.2. Syntheses and characterization
147.11, 145.51, 140.27, 138.84, 136.65, 135.91, 129.79, 127.86,
126.34, 124.53, 123.30, 122.85, 65.93, 43.69, 28.99, 27.76, 25.53,
24.22, 23.77, 22.32, 17.37. Elemental analysis calculated for
2.2.1. Synthesis of 2,6-(CH3)2C6H3eN]C(CH3)eC(CH3)(CH2Ph)e
NHe2,6-(CH3)2C6H3 (L3)
C
5.56.
35H48N2: C, 84.62; H, 9.74; N, 5.64. Found: C, 84.45; H, 9.81; N,
Under nitrogen atmosphere, a mixture of powdered magne-
sium (25 mmol) in anhydrous ether (45 mL) was stirred at 35 ꢀC.
R2
R2
R1
R1
R1
R1
R1
R1
R1
R1
R1
AlMe3 or
PdCl2
N
HN
N
NH
R1
N
N
PhCH2MgCl
MeOH
P
R1
R1
Cl
Cl
L1: R1 = Me, R2 = Me;
L2: R1 = iPr, R2 = Me;
L3: R1 = Me, R2 = CH2Ph;
L4: R1 = iPr, R2 = CH2Ph.
C1: R1 = Me, R2 = Me;
C2: R1 = iPr, R2 = Me;
C3: R1 = Me, R2 = CH2Ph;
C4: R1 = iPr, R2 = CH2Ph.
1a: R1 = Me;
1b: R1 = iPr;
Scheme 1. The synthetic route of a-iminoeamido ligands and palladium complexes.