112
Q. Li et al. / Journal of Organometallic Chemistry 745-746 (2013) 106e114
a head (carbene)eto tail (nitrogen) coordination mode, while the
latter show head (carbene)eto head (carbene) and tail (nitrogen)e
to tail (nitrogen) coordination modes to two silver atoms. Addi-
tionally, these NHC silver complexes exhibited high catalytic ac-
tivity in the three-component coupling reaction of alkyne,
aldehyde and amine to generate propargylamines. Further studies
on new organometallic complexes and their catalytic activity from
these precursors are ongoing in our laboratory.
(s, 6H, CH3), 5.48 (s, 2H, CH2), 6.20 (s, 2H, H4 of pyrazole), 6.74e7.07
(m, 2H), 7.27e7.55 (m, 5H), 7.75e7.87 (m, 3H), 7.80 (s, 2H) (protons
of C6H5, C6H4, CH and protons of imidazole) ppm. 13C NMR (DMSO-
d6):
d
11.2, 14.1 (CH3), 55.3 (CH2), 67.7 (CH), 106.8 (C4 of pyrazole),
122.5, 123.0, 124.1, 124.2, 128.3, 128.7, 129.3, 136.7, 137.2, 139.9,
143.5, 150.6 (carbons of C6H4, C6H5, imidazole and pyrazole), 180.3
(Ccarbene) ppm. Anal. Calc. for C54H56Ag2F12N12P2: C, 47.04; H, 4.09;
N, 12.19. Found: C, 47.50; H, 4.38; N, 11.78%.
3. Experimental
3.4. Reaction of 4 with Ag2O
1H and 13C NMR spectra were recorded using a Bruker 400
spectrometer, and the chemical shifts were reported in ppm with
respect to the reference (internal SiMe4 for 1H and 13C NMR
spectra). Element analyses were carried out using an Elementar
Vairo EL analyzer. HR mass spectra were obtained on a Varian
QFT-ESI spectrometer. Melting points were measured with an X-4
digital micro melting-point apparatus and were uncorrected. Bis(-
pyrazol-1-yl)methanone [38], bis(3,5-dimethylpyrazol-1-yl)meth-
anone [38], (2-hydroxyphenyl)bis(pyrazol-1-yl)methane [38], 4-
(1H-imidazol-1-yl)benzaldehyde [39] and 1-chloromethylimida
zole-hydrochloride [40] were prepared according to the literature
methods. Other reagents were of analytical grade and used without
further purification. The synthetic procedures and experimental
data for ligands 1e6 and 12e18 are listed in the Supporting
Information.
This reaction was carried out similarly using 4 instead of 3 as
described above. Complex 10 was obtained as a white solid. Yield:
97%, mp 187e188 ꢁC. 1H NMR (DMSO-d6):
d 2.07 (s, 6H, CH3), 2.10 (s,
6H, CH3), 5.36 (s, 2H, CH2), 5.92 (s, 2H, H4 of pyrazole), 7.11 (d,
J ¼ 8.4 Hz, 2H), 7.67 (d, J ¼ 8.4 Hz, 2H) (C6H4), 7.25e7.35 (m, 5H,
C6H5), 7.76 (s, 1H, CH), 7.91 (d, J ¼ 1.4 Hz, 1H), 7.80 (d, J ¼ 1.4 Hz, 1H)
(protons of imidazole) ppm. 13C NMR (DMSO-d6):
d 10.9, 13.4 (CH3),
54.5 (CH2), 71.6 (CH), 106.4 (C4 of pyrazole), 122.5, 123.2, 123.6,
127.7, 128.1, 128.6, 128.7, 136.7, 137.1, 139.5, 140.2, 147.1 (carbons of
C6H4, C6H5, imidazole and pyrazole), 179.6 (Ccarbene) ppm. Anal.
Calc. for C108H112Ag4Br4N24: C, 51.94; H, 4.52; N, 13.46. Found: C,
52.35; H, 5.01; N, 13.73%.
3.5. Reaction of 4 with Pd(OAc)2
The mixture of 4 (0.52 g, 1.0 mmol) and Pd(OAc)2 (0.22 g,
1.0 mmol) in CH3CN (20 ml) was stirred at room temperature for
24 h. The solution was filtered and concentrated to ca. 2 ml, ethanol
(10 ml) was added to give yellow solids of 11. Yield: 0.62 g (88%),
3.1. Reaction of 3 with Ag2O
The mixture of 3 (0.42 g, 1.0 mmol) and Ag2O (0.16 g, 0.7 mmol)
in CH3CN (20 ml) was stirred at room temperature for 24 h with
exclusion of light. The solution was filtered and concentrated to ca.
2 ml under reduced pressure, ethanol (10 ml) was added to give
white solids of 7. Yield: 0.50 g (96%), mp 164e166 ꢁC. 1H NMR
mp > 250 ꢁC. 1H NMR (CDCl3):
d 2.00 (s, 3H, CH3), 2.15 (s, 3H, CH3),
2.16 (s, 3H, CH3), 2.70 (s, 3H, CH3), 5.88 (d, J ¼ 14.7 Hz, 1H), 6.10 (d,
J ¼ 14.7 Hz, 1H) (CH2), 5.83 (s, 1H), 5.90 (s, 1H) (H4 of pyrazole), 6.81
(d, J ¼ 2.0 Hz,1H), 7.02 (d, J ¼ 2.0 Hz,1H) (protons of imidazole), 7.31
(d, J ¼ 8.3 Hz, 2H), 7.88 (d, J ¼ 8.3 Hz, 2H) (C6H4), 7.41e7.47 (m, 3H),
7.61e7.67 (m, 2H) (C6H5), 8.58 (s, 1H, CH) ppm. 13C NMR (CDCl3):
(DMSO-d6):
d
5.40 (s, 2H, CH2), 6.40 (t, J ¼ 2.0 Hz, 2H, H4 of pyr-
azole), 7.17 (d, J ¼ 8.4 Hz, 2H), 7.74 (d, J ¼ 8.4 Hz, 2H) (C6H4), 7.32e
7.36 (m, 5H, C6H5), 7.65 (d, J ¼ 1.8 Hz, 2H), 7.91 (d, J ¼ 1.9 Hz, 2H) (H3
and H5 of pyrazole), 7.80 (d, J ¼ 1.4 Hz, 1H), 7.89 (d, J ¼ 1.4 Hz, 1H)
(protons of imidazole), 8.21 (s, 1H, CH) ppm. 13C NMR (DMSO-d6):
d
11.7, 13.4, 14.1, 14.7 (CH3), 54.8 (CH2), 65.4 (CH), 105.3, 110.0 (C4 of
pyrazole), 121.0, 123.9, 127.8, 127.9, 128.6, 129.1, 134.0, 137.7, 139.3,
139.6, 147.0, 148.5, 151.1, 151.5 (carbons of C6H4, C6H5, imidazole and
pyrazole), 180.7 (Ccarbene) ppm. Anal. Calc. for C54H56Br4N12Pd2: C,
46.14; H, 4.02; N, 11.96. Found: C, 45.86; H, 4.38; N, 11.58%.
d
53.5 (CH2), 74.3 (CH), 105.3 (C4 of pyrazole), 121.5, 122.1, 122.9,
126.6, 127.0, 127.1, 127.6, 129.3, 135.6, 136.2, 138.8, 139.1 (carbons of
C6H4, C6H5, imidazole and pyrazole),177.4 (Ccarbene) ppm. Anal. Calc.
for C46H40Ag2Cl2N12: C, 52.74; H, 3.85; N, 16.05. Found: C, 52.43; H,
3.56; N, 16.41%.
3.6. Reaction of 14 with Ag2O
This reaction was carried out similarly using 14 instead of 3 as
described above. Complex 19 was obtained as a white solid. Yield:
3.2. Reaction of 5 with Ag2O
91%, mp 167e169 ꢁC. 1H NMR (CDCl3):
d 5.25 (s, 2H, CH2), 5.97 (s,
This reaction was carried out similarly using 5 instead of 3 as
described above. Complex 8 was obtained as a white solid. Yield:
2H, CH2), 6.28 (t, J ¼ 2.0 Hz, 2H, H4 of pyrazole), 6.76 (d, J ¼ 1.6 Hz,
1H), 6.84e6.86 (m, 2H), 7.06 (t, J ¼ 7.6 Hz, 1H), 7.17e7.21 (m, 3H),
7.32e7.43 (m, 6H), 7.58 (d, J ¼ 1.4 Hz, 2H) (C6H4, C6H5, protons of
imidazole and pyrazole), 7.92 (s, 1H, CH) ppm. 13C NMR (CDCl3):
83%, mp 146e148 ꢁC. 1H NMR (DMSO-d6):
d 5.39 (s, 2H, CH2), 6.53
(t, J ¼ 2.1 Hz, 2H, H4 of pyrazole), 6.93 (d, J ¼ 8.1 Hz, 2H), 7.67 (d,
J ¼ 8.1 Hz, 2H) (C6H4), 7.29e7.33 (m, 5H, C6H5), 7.72 (s, br, 2H), 8.18
(s, br, 2H) (H3 and H5 of pyrazole), 7.79 (d, J ¼ 1.3 Hz, 1H), 7.88 (d,
J ¼ 1.3 Hz, 1H) (protons of imidazole), 8.40 (s, 1H, CH) ppm. 13C NMR
d
56.1 (CH2), 73.1 (CH2), 78.2 (CH), 106.6 (C4 of pyrazole), 114.4,
120.8, 122.0, 123.6, 125.8, 127.9, 128.4, 128.9, 129.2, 129.5, 131.5,
134.9, 140.8, 152.4 (carbons of C6H4, C6H5, imidazole and pyrazole),
181.2 (Ccarbene) ppm. Anal. Calc. for C48H44Ag2Cl2N12O2: C, 52.05; H,
4.00; N, 15.18. Found: C, 52.29; H, 4.04; N, 15.09%.
(DMSO-d6):
d
53.6 (CH2), 73.0 (CH), 105.5 (C4 of pyrazole), 121.3,
122.4 (2 C), 126.5, 126.6, 127.0, 127.7, 131.4, 135.1, 135.6, 138.7, 141.0
(carbons of C6H4, C6H5, imidazole and pyrazole), 178.3 (Ccarbene
)
ppm. Anal. Calc. for C46H40Ag2F12N12P2: C, 43.62; H, 3.18; N, 13.27.
Found: C, 43.33; H, 3.38; N, 13.45%.
3.7. Reaction of 18 with Ag2O
This reaction was carried out similarly using 18 instead of 3 as
described above. Complex 20 was obtained as a white solid. Yield:
3.3. Reaction of 6 with Ag2O
91%, mp 248e249 ꢁC. 1H NMR (DMSO-d6):
d 5.01 (s, 2H, CH2), 5.98
This reaction was carried out similarly using 6 instead of 3 as
described above. Complex 9 was obtained as a white solid. Yield:
(s, 2H, CH2), 6.49 (t, J ¼ 1.9 Hz, 2H, H4 of pyrazole), 6.59 (d, J ¼ 7.4 Hz,
2H), 7.02 (d, J ¼ 7.4 Hz, 2H) (C6H4), 7.15e7.19 (m, 2H), 7.29e7.33 (m,
3H), 7.55 (J ¼ 1.3 Hz, 1H), 7.64 (s, 2H), 7.67 (d, J ¼ 1.3 Hz, 1H), 8.15 (s,
96%, mp 227e229 ꢁC. 1H NMR (DMSO-d6):
d 1.93 (s, 6H, CH3), 2.50