Q. Li et al. / Polyhedron 59 (2013) 29–37
35
and refluxed for 18 h. After cooling to room temperature, the sol-
vent was removed under reduced pressure. The residue was dis-
solved in water (100 ml), and then extracted with CH2Cl2
(3 ꢂ 50 ml). The organic layers were combined and dried over
anhydrous Na2SO4. After removing CH2Cl2, the residue was treated
with ethyl acetate under ultrasonic conditions for 10 min to give a
yellow solid. Yield: 5.4 g (74%), mp 152–154 °C. 1H NMR (CDCl3): d
4.24 (s, 5H, C5H5), 4.24–4.27 (m, 2H), 4.45–4.47 (m, 2H) (C5H4),
5.33 (s, 2H, CH2), 5.69 (s, 2H, CH2), 7.24 (s, 1H), 7.56 (s, 1H) (protons
of imidazole ring), 7.27–7.31 (m, 1H), 7.75–7.82 (m, 2H), 8.52 (d,
J = 4.6 Hz, 1H) (C5NH4), 10.16 (s, 1H, proton of imidazolium) ppm.
13C NMR (CDCl3): d 50.1 (CH2), 54.0 (CH2), 69.2 (C5H5), 69.6, 69.8,
78.5 (C5H4), 121.3, 122.7, 124.0, 124.1, 135.7, 137.7, 149.9, 152.1
(carbons of pyridyl and imidazole ring) ppm. Anal. Calc. for C20H20-
FeIN3: C, 49.51; H, 4.16; N, 8.66. Found: C, 49.55; H, 4.53; N, 8.66%.
J = 7.6 Hz, 1H), 8.55 (d, J = 4.0 Hz, 1H) (C5NH4), 7.52 (d,
J = 1.4 Hz, 1H), 7.55 (d, J = 1.4 Hz, 1H) (protons of imidazole ring)
ppm. 13C NMR (DMSO-d6): d 50.5 (CH2), 55.8 (CH2), 68.4 (C5H5),
68.6, 68.8, 83.4 (C5H4), 121.9, 122.2, 122.5, 123.3, 137.5, 149.6,
155.9 (carbons of pyridyl and imidazole ring), 179.9 (Ccarbene
)
ppm. Anal. Calc. for C20H19Ag2FeI2N3: C, 29.05; H, 2.32; N, 5.08.
Found: C, 29.14 (1a) and 29.18 (1b); H, 2.64 (1a) and 2.49
(1b); N, 5.12 (1a) and 5.03% (1b).
The single crystals of 1a suitable for X-ray analyses were ob-
tained by the following method. A drop of DMF (ca. 0.2 ml) was
added to the reaction solution (4 ml) in a test tube. This tube
was placed in ether atmosphere at room temperature for several
days to afford yellow single crystals. The single crystals of 1b suit-
able for X-ray analyses were obtained by the following method.
CH2Cl2 (1 ml) was added to the reaction solution (4 ml) in a test
tube, and then this tube was sealed by a rubber stopper, and placed
to evaporate the solvents slowly at room temperature for several
days to afford yellow single crystals.
3.3. Synthesis of N-ferrocenylmethyl-N0-(3-
pyridylmethyl)imidazolium iodide
The solution of 1-(3-pyridylmethyl)imidazole (0.78 g, 4.9 mmol)
and FcCH2N(CH3)3I (1.9 g, 4.9 mmol) in CH3CN (20 ml) was stirred
and refluxed for 18 h. After cooling to room temperature, the sol-
vent was removed under reduced pressure. The residue was purified
by column chromatography on silica using ethyl acetate/ethanol (1/
1 v/v) as eluent. The yellow eluate was concentrated to dryness to
give viscous oils. Yield: 0.6 g (25%). 1H NMR (CDCl3): d 4.24 (s, 5H,
C5H5), 4.27 (s, br, 2H), 4.46 (s, br, 2H) (C5H4), 5.33 (s, 2H, CH2),
5.70 (s, 2H, CH2), 7.20 (d, J = 7.8 Hz, 1H), 8.11 (d, J = 7.8 Hz, 1H) (pro-
tons of imidazole ring), 7.34–7.42 (m, 2H), 8.63 (d, J = 4.3 Hz, 1H),
8.75 (s, 1H) (C5NH4), 10.27 (s, 1H, proton of imidazolium) ppm.
13C NMR (CDCl3): d 50.1 (CH2), 50.3 (CH2), 69.1 (C5H5), 69.7, 69.8,
78.5 (C5H4), 122.0, 122.3, 124.3, 129.3, 135.1, 137.3, 149.9, 150.5
(carbons of pyridyl and imidazole ring) ppm. HRMS (ESI, m/z):
358.1005 (Calc. for C20H20FeN3+: 358.1007, [MꢀI]+, 40%).
3.6. Reaction of N-ferrocenylmethyl-N0-(2-pyridylmethyl)imidazolium
iodide with Ag2O in CH2Cl2
The mixture of N-ferrocenylmethyl-N0-(2-pyridylmethyl)imi-
dazolium iodide (80 mg, 0.16 mmol) and Ag2O (23 mg, 0.09 mmol)
in CH2Cl2 (20 ml) was stirred for 24 h at room temperature in the
dark. After filteration, the reaction solution was placed for several
days to evaporate the solvent slowly to give yellow single crystals
of complex 2. Yield: 28 mg (34%), mp 155–157 °C. 1H NMR
(DMSO-d6): d 4.16 (s, br, 2H), 4.38 (s, br, 2H) (C5H4), 4.20 (s, 5H,
C5H5), 5.06 (s, 2H, CH2), 5.46 (s, 2H, CH2), 7.28 (d, J = 7.8 Hz, 1H),
7.34 (dd, J = 4.9 Hz, J = 7.4 Hz, 1H), 7.80 (dt, J = 1.5 Hz, J = 7.7 Hz,
1H), 8.53 (d, J = 4.7 Hz, 1H) (C5NH4), 7.49 (d, J = 1.4 Hz, 1H), 7.53
(d, J = 1.4 Hz, 1H) (protons of imidazole ring) ppm. 13C NMR
(DMSO-d6): d 50.5 (CH2), 55.8 (CH2), 68.3 (C5H5), 68.6, 68.7, 83.5
(C5H4), 121.8, 122.0, 122.6, 123.2, 137.3, 149.5, 156.0 (carbons of
pyridyl and imidazole ring), 178.5 (Ccarbene) ppm. Anal. Calc. for
3.4. Synthesis of N-ferrocenylmethyl-N0-(4-
pyridylmethyl)imidazolium iodide
C
40H38Ag2Cl2Fe2N6: C, 47.99; H, 3.83; N, 8.39. Found: C, 47.63;
This ligand was obtained similarly using 1-(4-pyridylmethyl)
imidazole instead of 1-(3-pyridylmethyl)imidazole as described
above for N-ferrocenylmethyl-N0-(3-pyridylmethyl)imidazolium
iodide. Yield: 25%, mp 145–147 °C. 1H NMR (CDCl3): d 4.25 (s,
5H, C5H5), 4.28 (t, J = 1.7 Hz, 2H), 4.46 (t, J = 1.8 Hz, 2H) (C5H4),
5.34 (s, 2H, CH2), 5.71 (s, 2H, CH2), 7.22 (s, br, 1H), 7.33 (s, br,
1H) (protons of imidazole ring), 7.44 (d, J = 5.6 Hz, 2H), 8.64 (d,
J = 5.6 Hz, 2H) (C5NH4), 10.26 (s, 1H, proton of imidazolium) ppm.
13C NMR (CDCl3): d 50.4 (CH2), 51.8 (CH2), 69.3 (C5H5), 69.7, 70.0,
78.0 (C5H4), 121.7, 122.2, 123.4, 135.8, 141.6, 150.8 (carbons of
pyridyl and imidazole ring) ppm. Anal. Calc. for C20H20FeIN3: C,
49.51; H, 4.16; N, 8.66. Found: C, 49.18; H, 4.28; N, 8.62%.
H, 3.99; N, 8.27%.
3.7. Reaction of N-ferrocenylmethyl-N0-(3-pyridylmethyl)imidazolium
iodide with Ag2O
The mixture of N-ferrocenylmethyl-N0-(3-pyridylmethyl)imi-
dazolium iodide (80 mg, 0.16 mmol) and Ag2O (23 mg, 0.09 mmol)
in CH2Cl2 (20 ml) was stirred for 24 h at room temperature in the
dark. After filteration, the reaction mixture was concentrated to
ca. 2 ml, and ethanol (10 ml) was added. A yellow solid was
formed, which was filtered and washed with ethanol and ether
to give complex 3. Yield: 70 mg (72%), mp 104 °C (dec.). 1H NMR
(DMSO-d6): d 4.14 (s, br, 2H), 4.35 (s, br, 2H) (C5H4), 4.18 (s, 5H,
C5H5), 5.10 (s, 2H, CH2), 5.40 (s, 2H, CH2), 7.38–7.41 (m, 1H), 7.70
(d, J = 7.8 Hz, 1H), 8.52 (d, J = 3.8 Hz, 1H), 8.58 (s, 1H) (C5NH4),
7.54 (s, 1H), 7.55 (s, 1H) (protons of imidazole ring) ppm. 13C
NMR (DMSO-d6): d 50.6 (CH2), 56.0 (CH2), 68.7 (C5H5), 68.4, 68.8,
83.3 (C5H4), 122.0, 122.3, 123.9, 132.9, 135.6, 148.9, 149.3 (carbons
of pyridyl and imidazole ring), 180.0 (Ccarbene) ppm. Anal. Calc. for
C40H38Ag2Fe2I2N6: C, 40.58; H, 3.23; N, 7.10. Found: C, 40.15; H,
3.62; N, 7.36%.
3.5. Reaction of N-ferrocenylmethyl-N0-(2-pyridylmethyl)imidazolium
iodide with Ag2O
The mixture of N-ferrocenylmethyl-N0-(2-pyridylmethyl)imi-
dazolium iodide (80 mg, 0.16 mmol) and Ag2O (23 mg,
0.09 mmol) in acetone (20 ml) was stirred at room temperature
for 24 h in the dark. After filteration, the mother liquid was con-
centrated to dryness to give a yellow solid of 1a. Yield: 50 mg
(36%, based on the imidazolium salt), mp 96–98 °C. While the
reaction was carried out in CH3CN, a yellow solid of 1b was ob-
tained. Yield: 29% (based on the imidazolium salt), mp 84–86 °C.
Complexes 1a and 1b displayed the same NMR spectroscopic
data within experimental error. 1H NMR (DMSO-d6): d 4.13 (s,
br, 2H), 4.35 (s, br, 2H) (C5H4), 4.16 (s, 5H, C5H5), 5.10 (s, 2H,
CH2), 5.48 (s, 2H, CH2), 7.29–7.38 (m, 2H), 7.81 (dt, J = 1.6 Hz,
The single crystals of 3 suitable for X-ray analyses were ob-
tained by the following method. Hexane was slowly added over
the DMF solution of 3 in a test tube, and then this tube was placed
in ether atmosphere at room temperature for several days to afford
yellow single crystals.