Article
Organometallics, Vol. 30, No. 2, 2011 343
þ
(
imidazole-C4/C5). MS (EI, 20 eV): m/z (%) 276 (100) [M] .
Anal. Calcd (%): C, 65.20; H, 4.38; N, 30.42. Found: C, 65.27; H,
.26; N, 30.35. The spectroscopic data match those reported in ref 23.
Synthesis of 1,2,4,5-Tetrakis(3-n-butyl-1-imidazolium)benzene
Tetrabromide, H -2a(Br) . A sample of 1,2,4,5-tetrakis(1-
imidazolyl)benzene (1; 0.7 g, 2.05 mmol) was dissolved in DMF
10 mL), and n-butyl bromide (2.263 g, 16.4 mmol) was added.
Synthesis of 1,3,5-Tris(3-n-buyl-1-imidazolium)benzene Tribro-
mide, H -4a(Br) . A sample of 1,3,5-tris(1-imidazolyl)benzene
3 3
4
3 (1.2 g, 4.35 mmol) and n-butyl bromide (6.0 g, 43.5 mmol)
were dissolved in DMF (15 mL) and heated to 100 °C for 2 days.
A white precipitate formed during this time, which was isolated
by filtration, washed with diethyl ether (3 ꢀ 15 mL), and dried
4
4
(
in vacuo to yield the bromide salt H
3
-4a(Br)
3
as white solid. Yield:
]DMSO): δ
10.62 (t, J = 1.4 Hz, 3H, N-CH-N), 8.81 (s, 3H, Ar-H), 8.78 (dd,
1
The reaction mixture was heated for 40 h at 100 °C, during which
time a white precipitate formed. The precipitate was isolated by
filtration and washed with diethyl ether. The solid residue was
dissolved in methanol and precipitated with diethyl ether to give
2.10 g (3.05 mmol, 70%). H NMR (400 MHz, [d
6
4
3
4
3
J = 2.2 Hz, J=1.4 Hz, 3H, imidazole-H5), 8.23 (dd, J=2.2
4
3
Hz, J = 1.4 Hz, 3H, imidazole-H4), 4.35 (t, J = 7.19 Hz, 6H,
NCH ), 1.97 (m, 6H, NCH CH ), 1.36 (m, 6H, CH CH CH ),
0.96 ppm (t, J = 7.34 Hz, 9H, CH ). C{ H} NMR (100 MHz,
[d ]DMSO):δ136.34 (Ar-C-N), 136.10 (N-C-N), 123.76 (imidazole-
C4), 120.99 (imidazole-C5), 115.35 (Ar-C-H), 49.45 (NCH
30.86 (NCH CH ), 18.76 (CH CH CH ), 13.22 ppm (CH
MS (ESI, positive ions): m/z 223.1581 (calcd for [H
223.1579). Anal. Calcd (%) for H -4a(Br) O: C, 45.97; H,
H
(
4
4
-2a(Br)
1.41 mmol, 69%). H NMR (400 MHz, [d
H, N-CH-N), 8.97 (s, 2H, Ar-H), 8.14 (m, 8H, imidazole-H4
4
as a colorless solid after drying in vacuo. Yield: 1.25 g
2
2
2
2
2
2
1
3
13
1
6
]DMSO): δ 10.24 (s,
3
6
3
and imidazole-H5), 4.31 (t, J = 7.18 Hz, 8H, NCH
2
), 1.90
), 0.94 ppm
t, J = 7.35 Hz, 12H, CH ). C{ H} NMR (100 MHz, [d ]-
2
),
).
(
(
m, 8H, NCH
2
CH
2
), 1.32 (m, 8H, NCH
2
CH
2
CH
2
2
2
2
2
2
3
3
13
1
2þ
2
-4a]
3
6
DMSO): δ 138.40 (N-C-N), 130.40 (Ar-C-N), 128.40 (Ar-C-H),
3
3
3 H
2
1
23.60 (imidazole-C4), 122.70 (imidazole-C5), 49.40 (NCH2),
0.80 (NCH CH ), 18.70 (CH CH CH ), 13.20 ppm (CH ).
5.86; N, 11.92. Found: C, 45.38; H, 5.70; N, 12.02.
Synthesis of 1,3,5-Tris(3-n-buyl-1-imidazolium)benzene Tris-
3
MS (ESI, positive ions): m/z 284.1987 (calcd for [H
2
5
2
2
2
2
2
3
2
þ
(
(
hexafluorophosphate), H -4a(PF ) . A solution of NH PF
3 6 3 4 6
2
-2a]
0.326 g, 2.0 mmol) in methanol (3 mL) was added slowly to a
-4a(Br) (0.342 g, 0.50 mmol) in methanol (5 mL).
The white hexafluorophosphate salt H -4a(PF precipitated
84.2001). Anal. Calcd (%) for H -2a(Br) 2H O: C, 44.08; H,
4
.88; N, 12.10. Found: C, 44.25; H, 5.85; N, 11.75.
Synthesis of 1,2,4,5-Tetrakis(3-n-butyl-1-imidazolium)benzene
4
3
2
solution of H
3
3
3
6 3
)
immediately and was collected by filtration and washed with
small portions of cold methanol and diethyl ether. Drying in
Tetrakis(hexafluorophosphate), H -2a(PF ) . A solution of
4
6 4
NH
slowly to a solution of H
methanol (7 mL). The white hexafluorophosphate salt H4-
a(PF ) precipitated immediately and was collected by fil-
4
PF
6
(0.896 g, 5.5 mmol) in methanol (3 mL) was added
3 6 3
vacuo gave H -4a(PF ) as a colorless solid. Yield: 0.34 g (0.385
4
-2a(Br) (0.886 g, 1.0 mmol) in
4
1
mmol, 77%). H NMR (400 MHz, [d
4
6
]DMSO): δ 9.89 (t, J =
3
.4 Hz, 3H, N-CH-N), 8.51 (s, 3H, Ar-H), 8.41 (dd, J = 2.4 Hz,
1
2
6
4
4
3
4
J = 1.4 Hz, 3H, imidazole-H5), 8.20 (dd, J = 2.4 Hz, J = 1.4
tration and washed with small portions of cold methanol and
diethyl ether. Drying in vacuo gave H -2a(PF as a colorless
solid. Yield: 1.024 g (0.89 mmol, 89%). H NMR (400 MHz,
]DMSO): δ 9.55 (s, 4H, N-CH-N), 8.64 (s, 2H, Ar-H), 8.13
s, 4H, imidazole-H5), 7.91 (s, 4H, imidazole-H4), 4.30 (t,
3
Hz, 3H, imidazole-H4), 4.35 (t, J = 7.25 Hz, 6H, NCH
2
), 1.92
4
6 4
)
1
(
m, 6H, NCH CH ), 1.38 (m, 6H, CH CH CH ), 0.97 ppm (t,
2
2
2
2
2
3
13
J = 7.37 Hz, 9H, CH3). C{ H} NMR (100 MHz, [d ]DMSO):
1
[
d
6
6
δ 136.40 (Ar-C-N), 135.66 (N-C-N), 124.01 (imidazole-C4),
21.12 (imidazole-C5), 116.19 (Ar-C-H), 49.56 (NCH ), 30.99
(
3
1
2
J = 7.18 Hz, 8H, NCH
2 2 2
), 1.84 (m, 8H, NCH CH ), 1.31 (m,
3
H, CH CH CH ), 0.94 ppm (t, J = 7.36 Hz, 12H, CH ).
(
positive ions): m/z 737.2500 (calcd for [H
NCH CH ), 18.75 (CH CH CH ), 13.20 ppm (CH ). MS (ESI,
3
8
2
2
2
2
2
2
2
2
3
þ
1
3
1
-4a(PF
6
)
2
] 737.2520),
6
C{ H} NMR (100 MHz, [d ]DMSO): δ 137.68 (N-C-N),
3
2
)] 296.1439), 223.1582 (calcd
þ
2
for [H
96.1444 (calcd for [H
3
-4a(PF
6
1
1
1
31.00 (Ar-C-N), 128.18 (Ar-C-H), 124.01 (imidazole-C4),
23.05 (imidazole-C5), 49.59 (NCH ), 31.03 (NCH CH ),
2
-4a] 223.1579). Satisfactory microanalytical data for
þ
2
2
2
2
H -4a(PF ) could not be obtained due to the large amount of
6 3
8.68 (CH CH CH ), 13.20 ppm (CH ). MS (ESI, positive
2
3
2
2
3
þ
1005.3075),
430.1715), 238.4593 (calcd
fluorine present.
Synthesis of 1,3,5-Tris(3-ethyl-1-imidazolium)benzene Tribro-
ions): m/z 1005.3073 (calcd for [H
4
-2a(PF
6
)
3
]
2þ
430.1710 (calcd for [H -2a(PF
4
6 2
) ]
3
þ
mide, H
(
3 3
-4b(Br) . A sample of 1,3,5-tris(1-imidazolyl)benzene
3; 1.2 g, 4.35 mmol) and ethyl bromide (4.74 g, 43.5 mmol) were
for [H -2a(PF )] 238.4595). Satisfactory microanalytical
4
6
data for H
amount of fluorine present.
4
6 4
-2a(PF ) could not be obtained due to the large
dissolved in DMF (15 mL) and heated to 100 °C for 2 days. A
white precipitate formed during this time, which was isolated
by filtration, washed with diethyl ether (3 ꢀ 15 mL), and dried
Synthesis of 1,2,4,5-Tetrakis(3-ethyl-1-imidazolium)benzene
Tetrabromide, H -2b(Br) . A sample of 1,2,4,5-tetrakis(1-
4
4
in vacuo to yield the crude bromide salt H -4b(Br) . Yield: 1.97 g
imidazolyl)benzene (1; 0.5 g, 1.462 mmol) was dissolved in DMF
8 mL), and ethyl bromide (1.275 g, 11.70 mmol) was added. The
3
3
(
3.26 mmol, 75%). The crude bromide salt H
not further purified but used directly for the preparation of
H -4b(PF ) .
3 3
-4b(Br) was
(
reaction mixture was heated for 40 h at 100 °C, during which
time a white precipitate formed. The precipitate was isolated
by filtration and washed with diethyl ether. Yield: 1.0 g (1.286
3
6 3
Synthesis of 1,3,5-Tris(3-ethyl-1-imidazolium)benzene Tris-
hexafluorophosphate), H -4b(PF . The crude bromide salt H
was converted to H -4b(PF by adding a solution of
(2.119 g, 13 mmol) in methanol (4 mL) to a methanolic
-4b(Br) (1.97 g, 3.26 mmol). The pre-
(
4
NH
3
6
)
3
3
-
4 4
mmol, 88%). The crude bromide salt H -2b(Br) obtained this
b(Br)
3
3
6 3
)
way was not further purified but used directly for the preparation
of H -2b(PF ) .
PF
4 6
4
6 4
Synthesis of 1,2,4,5-Tetrakis(3-ethyl-1-imidazolium)benzene
Tetrakis-(hexafluorophosphate), H -2b(PF . The hexafluoro-
phosphate salt H -2b(PF ) was synthesized as described for the
solution (30 mL) of H
3
3
4
6
)
4
cipitated white hexafluorophosphate salt was collected by filtra-
tion and washed with small portions of cold methanol and diethyl
4
6 4
preparation of H
-2b(Br) and 1.152 g (7.07 mmol) of NH
powder. Yield: 1.11 g (1.069 mmol, 83%). H NMR (400 MHz,
CD CN): δ 9.12 (s, 4H, N-CH-N), 8.29 (s, 2H, Ar-H), 7.65 (s,
4
-2a(PF
6
)
4
starting from 1.0 g (1.286 mmol) of
ether. Dryinginvacuo gave H
3
-4b(PF
2.08 g(2.61 mmol,80%). H NMR (400 MHz, CD
3H, N-CH-N), 8.12 (s, 3H, Ar-H), 7.95 (s, 3H, imidazole-H5),
6
)
3
asa colorlesssolid. Yield:
1
H
4
4
4
1
PF as an off-white
6
CN):δ9.15(s,
3
3
7.73 (s, 3H, imidazole-H4), 4.36 (q, J = 7.33 Hz, 6H, NCH
2
),
). C{ H} NMR (100 MHz,
CN): δ 138.25 (Ar-C-N), 136.15 (N-C-N), 124.92 (imidazole-
C4), 122.87 (imidazole-C5), 119.24 (Ar-C-H), 47.10 (NCH ),
15.20 ppm (CH ). MS (ESI, positive ions): m/z 653.1566 (calcd
for [H -4b(PF
3
3
3
13
1
4
H, imidazole-H5), 7.48 (s, 4H, imidazole-H4), 4.32 (q, J = 7.3
1.61 ppm (t, J = 7.33 Hz, 9H, CH
CD
3
3
13
1
Hz, 8H, NCH
NMR (100 MHz, CD
2
), 1.56 ppm (t, J = 7.3 Hz, 12H, CH
CN): δ 137.88 (N-C-N), 133.14 (Ar-C-N),
30.03 (Ar-C-H), 125.34 (imidazole-C4), 124.17 (imidazole-C5),
3
). C{ H}
3
3
2
1
4
8
3
þ
7.31 (NCH
93.1854 (calcd for [H -2b(PF ) ] 893.1826). Satisfactory
2
), 15.08 ppm (CH
3
). MS (ESI, positive ions): m/z
3
6
)
2
]
653.1575), 254.0961 (calcd for [H
)] 254.0964). Satisfactory microanalytical data for H
4b(PF could not be obtained due to the large amount of
fluorine present.
3
-4b-
þ
2þ
(PF
-
3
4
6 3
6
microanalytical data for H
4
-2b(PF
due to the large amount of fluorine present.
6
)
4
could not be obtained
6 3
)