Organometallics
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(found, %): C 71.59, H 4.17, N 7.61 (calcd., C 71.86, H 4.46, N
7.29).
Table 5. Crystal Data and Structure Refinement for Pd-L3
and Pd-L4
1-(2-(Diphenylphosphanyl)thiophen-3-yl)-3-methyl-1H-benzimi-
dazol-3-ium trifluoromethanesulfonate (L2). Under N2 atmosphere,
a solution of L1 (0.79 g, 2 mmol) in dry dichloromethane was cooled
to −78 °C and then methyltrifluoromethanesulfonate (MeOTf, 0.33
g, 2 mmol) was added dropwise. The obtained mixture was stirred for
1 h at −78 °C and then warmed up to room temperature naturally.
After removal of solvent under vacuum, the residue was recrystallized
in dichloromethane/diethyl ether to give product of L2 as a white
Pd-L3
Pd-L4
empirical formula
formula weight
crystal system
space group
a (Å)
b (Å)
c (Å)
α (deg)
β (deg)
C35H26Cl2N2P2PdS
745.88
monoclinic
C2/c
33.2928(14)
10.3314(4)
19.5991(9)
90
96.624(4)
90
6696.3(5)
8
1.480
7.636
100
C24H19Cl2N2PPdS
575.74
monoclinic
P21/n
10.97340(10)
15.11960(10)
13.54790(10)
90
92.3220(10)
90
2245.93(3)
4
1.703
10.516
100
1
solid (0.58 g, yield of 73%). H NMR (CDCl3, ppm): 9.55 (s, 1H,
NCHN), 7.78−7.83 (m, 2H, SCHCH), 7.68−7.73 (m, 1H, CCH),
7.56−7.60 (m, 1H, CCH), 7.50 (dd, 1H, NCCH), 7.32−7.46 (m,
11H, PPh2+NCCH), 4.22 (s, 3H, CH3). 31P NMR (CDCl3, ppm):
−26.0 (s, PPh2). CHN elemental analysis of L2 (C25H20F3N2O3PS2)
(found, %): C 54.95, H 3.48, N 4.92 (calcd., C 54.74, H 3.68, N
5.11).
γ (deg)
V (Å3)
Z
d
calc(g cm−3
)
2-(Diphenylphosphanyl)-1-(2-(diphenylphosphanyl)thiophen-
3′-yl)-1H-benozimidazole (L3). L3 was obtained with a yield of 69%
according to the preparation procedures for L1. A small difference
between the preparation procedures of L1 and L3 is that when the
temperature droped to −78 °C, N,N,N′,N′-tetramethylethylenedi-
amine (2 equiv) was added to the reaction solution before n-BuLi. A
sample suitable for X-ray diffraction analysis was obtained by slow
volatilization of an petroleum ether/ethyl acetate (5:1) solution
containing L3. 1H NMR (CDCl3, ppm): 7.91 (d, 1H, SCH), 7.60 (dd,
1H, SCCH), 7.52 (td, 2H, 2CCH), 7.43−7.48 (m, 2H, PPh2), 7.32−
7.36 (m, 17H, PPh2), 7.16 (t, 1H, PPh2), 6.97 (d, 1H, NCCH), 6.77
(dd, 1H, NCCH). 31P NMR (CDCl3, ppm): −25.7 (d, P1Ph2), −29.3
(d, P2Ph2). CHN elemental analysis of L3 (C35H26N2P2S) (found,
%): C 74.16, H 4.38, N 5.23 (calcd, C 73.93, H 4.61, N 4.93).
2-(Diphenylphosphanyl)-1-(2-(diphenylphosphanyl)thiophen-
3′-yl)-3-methyl-1H-benzimidazol-3-ium trifluoromethanesulfonate
(L4). L4 was obtained with a yield of 65% after the quaternization of
L3 by MeOTf according to the preparation procedures for L2. A
sample suitable for X-ray diffraction analysis was obtained by slow
volatilization of an dichloromethane/diethyl ether (1:5) solution
μ (mm−1
T (K)
)
λ(Cu Kα) (A)
total reflections
unique reflections (Rint)
R1 [I ≥ 2σ(I)]
wR2 (all data)
F (000)
1.54184
30865
5950 (0.1131)
0.1477
0.3043
3008
1.54184
55168
3980 (0.1174)
0.0444
0.1162
1152
Wax capillary column (30 m × 0.25 mm × 0.25 μm). TG/DTG
analysis was performed on a thermogravimetric analyzer (TGA/
SDTA/SF/1100/851e). FT-IR spectra were obtained using a Nicolet
NEXUS 670 spectrometer. The amounts of Pd and P in the sample
were quantified by using an inductively coupled plasma optical
emission spectrometer (ICP-OES) on an Optima 8300 instrument
(PE Corporation).
Synthesis. 1-(2-(Diphenylphosphanyl)thiophen-3-yl)-1H-benzi-
midazole (L1). L1 was prepared according to the procedures reported
by our group37 with some modifications. Under N2 atmosphere,
benzimidazole (5.90 g, 50 mmol), 3-bromothiophene (9.78 g, 60
mmol), L-proline (2.30 g, 20 mmol), K2CO3 (14.51 g, 105 mmol),
and CuI (1.91 g, 10 mmol) were added to DMSO (150 mL), and the
mixture was stirred vigorously at 130 °C for 24 h. Water (150 mL)
was added to the system after completion of the reaction, and the
mixture was extracted with ethyl acetate (3 × 80 mL). After drying
with anhydrous sodium sulfate, the combined organic phase was
concentrated by vacuum. The residue was purified by column
chromatography on silica gel, using petroleum ether/ethyl acetate
(2:1) as eluant, to give the product 1-(thiophen-3-yl)-1H-
benzimidazole as a white solid (5.60 g, yield of 56%). 1H NMR
(CDCl3, ppm): 8.15 (s, 1H, NCHN), 7.90−7.92 (m, 1H, NCCH),
7.56−7.60 (m, 2H, 2SCH), 7.45 (dd, 1H, NCCH), 7.38−7.40 (m,
2H, 2CCH), 7.35 (dd, 1H, SCCH).
Under N2 atmosphere, a solution of 1-(thiophen-3-yl)-1H-
benzimidazole (2.00 g, 10 mmol) in dry THF (100 mL) was cooled
to −78 °C, and then n-BuLi (2.5 M in hexane, 4.40 mL, 11 mmol)
was added dropwise. After stirring vigorously for 1 h, the obtained
reaction mixture was added dropwise to chlorodiphenylphosphine
(PPh2Cl, 2.30 g, 11 mmol). The resultant mixture was stirred for
another 1 h at −78 °C and then warmed up to room temperature
naturally. After quenching the excess n-BuLi with deionized water, the
mixture was extracted with ethyl acetate (3 × 80 mL), and the
combined organic phase was concentrated by vacuum. The residue
was purified by column chromatography on silica gel, using petroleum
ether/ethyl acetate (3:1) as eluant, to give product L1 as a white solid
1
containing L4. H NMR (CDCl3, ppm): 8.02 (d, 1H, SCH), 7.66−
7.71 (m, 2H, 2CCH), 7.27−7.58 (m, 21H, 2PPh2 + SCH), 7.08 (dd,
1H, NCCH), 6.92 (d, 1H, NCCH), 3.79 (s, 3H, CH3). 31P NMR
(CDCl3, ppm): −16.8 (d, P1Ph2), −30.3 (d, P2Ph2). CHN elemental
analysis of L4 (C37H29F3N2O3P2S2) (found, %): C 60.89, H 4.33, N
4.11 (calcd, C 60.65, H 3.99, N 3.82).
Pd(II)-Complexes Pd-L3 and Pd-L4. Under N2 atmosphere, L3
(0.23 g, 0.4 mmol) and PdCl2(MeCN)2 was dissolved in dry
dichloromethane (2 mL). The mixture was stirred for 1 h at 100 °C.
Then dichloromethane was removed to obtain a yellow solid, which
was dried under vacuum to give product Pd-L3 in a yield of 78%
(0.23 g). A sample suitable for X-ray diffraction analysis was obtained
by recrystallization from dichloromethane/methanol. 31P NMR
(DMSO-d6, ppm): 14.9 (d, P1Ph2), 17.1 (d, P2Ph2). CHN lemental
analysis of Pd-L3 (C35H26Cl2N2P2PdS) (found, %): C 56.66, H 3.23,
N 3.92 (calcd, C 56.36, H 3.51, N 3.76).
Pd(II)-complex Pd-L4 was prepared with a yield of 85% by
following procedures similar to that described above for Pd-L3. A
sample suitable for X-ray diffraction analysis was obtained by
recrystallization from THF/MeOH. 31P NMR (DMSO-d6, ppm):
14.2 (s, PPh2 ). CHN elemental analysis of Pd-L4
(C24H19Cl2N2PPdS) (found, %): C 50.29, H 3.23, N 4.66 (calcd, C
50.06, H 3.33, N 4.87).
X-ray Crystallography. Intensity data were collected for L3, L4,
Pd-L3, and Pd-L4 on a Bruker SMARTAPEX II diffractometer using
graphite monochromated Mo Kα radiation (λ = 0.71073 Å) at 296 K.
Data reduction included absorption corrections by the multiscan
method. The structures were solved by direct methods and refined by
full matrix least-squares using SHELXS-97 (Sheldrick, 1990), with all
nonhydrogen atoms refined anisotropically. Hydrogen atoms were
added at their geometrically ideal positions and refined isotropically.
The crystal data and refinement details of Pd-L3 and Pd-L4 are given
1
(2.34 g, yield of 61%). H NMR (CDCl3, ppm): 7.87−7.90 (m, 2H,
SCHCH), 7.75 (dd, 1H, NCHN), 7.36−7.43 (m, 12H, PPh2
+
2NCCH), 7.33−7.35 (m, 2H, 2CCH). 31P NMR (CDCl3, ppm):
−28.3 (s, PPh2). CHN elemental analysis of L1 (C23H17N2PS)
1039
Organometallics 2021, 40, 1032−1041