P. O. Asekunowo et al.
at room temperature for 3 h and allowed to stand overnight. Then
the solvent was removed under reduced pressure and the resultant
beige powder was washed with distilled water (3×5 ml) to remove
unreacted KPF6, and air dried. The product formed was collected
and washed with diethyl ether to produce a fine, pale beige solid.
Recrystallization from acetonitrile gave a crystalline solid. Yield
1.25 g (67%); m.p. 221–223 °C. 1H NMR (500 MHz, DMSO-d6, 298 K,
δ, ppm): 4.80 (s, 8H, 4 × N–CH2); 5.10 (d, J =6.0Hz, 8H, 4 × N–CH2–CH)
118.3 (benzimidazolium-CH7); 121.2 (benzimidazolium-CH8);
127.9 (benzimidazolium-CH9); 187.97, 190.56 ((d, 1 J(C–109Ag)
=209.5 Hz and d, 1 J(C–107Ag) =181.0 Hz). FT-IR (KBr disc, cmꢀ1):
3117, 3005 (C–HAr); 2984, 2957 (C–Haliph); 1390, 1439 (C–NAr);
1661 (C¼C, allyl). Anal. Calcd for C24H28AgF6N4P (%): C, 46.08; H,
4.48; N, 8.96. Found (%): C, 46.42; H, 4.55; N, 9.21.
Synthesis of 1-cyanopropyl-3-allylbenzimidazolium silver(I) hexafluorophosp
hate (9)
2
3
5.40 (dd, 4H, JHH =1.6Hz, JHH =10.0Hz, CH¼HHcis); 5.47 (dd, 4H,
3
2JHH =1.6Hz, JHH =17.5 Hz, CH¼CHHtrans); 6.00 (m, 4H, 4 × CH);
A mixture of 4 (0.60 g, 1.96 mmol) and Ag2O (0.45g, 1.96 mmol) in
dichloromethane (40 ml) was stirred at room temperature for
24h. The reaction mixture was filtered through Celite to remove
unreacted silver and the solvent was removed under reduced pres-
sure, which was then reacted with a solution of KPF6 (1 equiv.) in
methanol (20 ml) The mixture was stirred at room temperature for
3 h and allowed to stand overnight. The solvent was removed
under reduced pressure and the resultant white powder was
washed with distilled water (3× 5 ml) to remove unreacted KPF6,
and air dried. The compound was further purified by acetonitrile–
dichloromethane to give a crystalline solid. Single crystals suitable
for X-ray analysis were obtained by the slow diffusion of diethyl
ether into acetonitrile solution containing the complex. Yield 0.7g
(61%); m.p. 191–193 °C. 1H NMR (500 MHz, DMSO-d6, 298 K, δ,
ppm): 2.25 (m, 4H, 2 × CH2–CH2–CN); 2.60 (t, J =7.5 Hz, 4H,
2 × CH2–CN); 4.70 (t, J =7.5 Hz, 4H, 2 × N–CH2–CH2–CH2–CN); 5.25
7.44 (d, J =8.0 Hz, 4H, benzimidazolium-H6); 7.45 (d, J =8.0Hz, 4H,
benzimidazolium-H7); 7.82 (t, J =8.0Hz, 4H, benzimidazolium-H8);
7.90 (t, J =8.0 Hz, 4H, benzimidazolium-H9). 13C{1H} NMR (125 MHz,
DMSO-d6, 298 K, δ, ppm): 30.7 (N–CH2–CH2); 44.0 (N–CH2); 49.0
(N–CH2–CH); 53.4 (–CH¼CH2); 110.5 (benzimidazolium-CH6); 117.2
(benzimidazolium-CH7); 124.8 (benzimidazolium-CH8); 128.7
(benzimidazolium-CH9); 188.4 (C2 –Ag). FT-IR (KBr disc, cmꢀ1):
3219, 3125 (C–HAr); 2991, 2945 (C–Haliph); 1350, 1464, 1465, 1485
(C–NAr); 1691 (C¼C, allyl). Anal. Calcd for C44H44Ag2F12N8P2 (%): C,
44.36; H, 3.69; N, 9.41. Found (%): C, 44.67; H, 3.97; N, 9.71.
Synthesis of 1,1-diallyl-3,3-propylenedibenzimidazolium disilver(I) bis(hexafluo-
rophosphate) (7)
Complex 7 was prepared according to the same procedure as 6, ex-
cept that 1 was replaced with 2 (0.68 g, 0.96 mmol) and Ag2O
(0.44g, 1.92 mmol). Single crystals suitable for X-ray analysis were
obtained by the slow diffusion of diethyl ether into acetonitrile so-
lution containing the complex. Yield 1.35g (70%); m.p. 225–227 °C.
1H NMR (500 MHz, DMSO-d6, 298 K, δ, ppm): 2.68 (br quint, J =7.0Hz,
4H, 2 × N–CH2–CH2); 4.80 (t, J =7.0 Hz, 8H, 4 ×N–CH2); 5.10 (d, J =6.0.
2
(d, J =6.0 Hz, 4H, 2 × N–CH2–CH); 5.30 (dd, 2H, JHH =1.5 Hz,
2
3
3JHH =10.2 Hz, CH¼HHcis); 5.35 (dd, 2H, JHH =1.5 Hz, JHH =17.0 Hz,
CH¼CHHtrans); 6.06 (m, 2H, 2 × CH); 7.60–7.72 (m, 4H,
benzimidazolium-H6/H7); 7.87–8.00 (m, 2H, benzimidazolium-H8);
8.05–8.15 (m, 2H, benzimidazolium-H9). 13C{1H} NMR (125 MHz,
DMSO-d6, 298 K, δ, ppm): 30.3 (CH2–C ≡N); 44.0 (N–CH2); 51.7
(N–CH2–CH); 53.2 (–CH¼); 116.5 (C ≡ N); 120.2 (¼CH2); 117.4
(benzimidazolium-CH6); 120.0 (benzimidazolium-CH7); 125.7
(benzimidazolium-CH8); 129.5 (benzimidazolium-CH9); 189.0
(C2′–Ag). FT-IR (KBr disc, cmꢀ1): 3105, 3042 (C–HAr); 2986, 2960
(C–Haliph); 1396, 1459 (C–NAr); 1661 (C¼C, allyl); 2237 (C ≡ N).
Anal. Calcd for C28H30AgF6N6P (%): C, 47.80; H, 4.37; N, 11.95.
Found (%): C, 47.88; H, 4.74; N, 12.24.
2
3
Hz, 8H, 4 × N–CH2–CH); 5.38 (dd, 4H, JHH =1.6Hz, JHH =10.0Hz,
CH¼HHcis); 5.45 (dd, 4H, 2JHH =1.6 Hz, 3JHH =17.5 Hz, CH¼CHHtrans);
5.95 (m, 4H, 4 × CH); 7.44 (d, J =8.0Hz, 4H, benzimidazolium-H6);
7.45 (d, J =8.0Hz, 4H, benzimidazolium-H7); 7.79 (t, J =8.0 Hz, 4H,
benzimidazolium-H8); 8.10 (t, J =8.0Hz, 4H, benzimidazolium-H9).
13C{1H} NMR (125 MHz, DMSO-d6, 298 K, δ, ppm): 30.7 (N–CH2–CH2);
44.0 (N–CH2); 51.2 (–CH¼CH2); 110.5 (benzimidazolium-CH6);
117.2 (benzimidazolium-CH7); 124.8 (benzimidazolium-CH8);
128.7 (benzimidazolium-CH9); 189.8 (C2′–Ag). FT-IR (KBr disc,
cmꢀ1): 3029, 3125 (C–HAr); 2991, 2945 (C–Haliph); 1396, 1449,
1457, 1488 (C–NAr); 1694 (C¼C, allyl). Anal. Calcd for
Synthesis of 1-pentyl-3-allylbenzimidazolium silver(I) hexafluorophosphate (10)
C
46H48Ag2F12N8P2 (%): C, 45.32; H, 3.94; N, 9.19. Found (%): C,
To a suspension of 5 (0.50 g, 1.62mmol) in acetonitrile (40 ml) was
added Ag2O (0.38 g, 1.62mmol). The mixture was stirred at
50–60 °C for 12 h with the exclusion of light. The obtained solution
was filtered through a pad of Celite and the filtrate was slowly evap-
orated to precipitate a greyish solid. The compound was further pu-
rified by acetonitrile–dichloromethane to give a crystalline solid.
Compound 10 was isolated as a grey powder. Yield 0.62 g (65%);
m.p. 201–203 °C. 1H NMR (500 MHz, DMSO-d6, 298K, δ, ppm): 0.86
(t, J =7.0Hz, 6H, 2 × CH3); 1.15 (m, 4H, 2 × CH2–CH3); 1.30 (m, 4H,
2 × CH2–CH2–CH3); 1.90 (m, 4H, 2 × N–CH2–CH2); 4.55 (t, J =7.0 Hz,
4H, 2 × N–CH2–R); 5.25 (d, J =6.0Hz, 4H, 2 × N–CH2–CH); 5.30 (dd,
45.71; H, 4.32; N, 9.47.
Synthesis of 1-ethyl-3-allylbenzimidazolium silver(I) hexafluorophosphate (8)
To a suspension of 3 (0.80 g, 2.97 mmol) in acetonitrile (40 ml) was
added Ag2O (0.69g, 2.97 mmol). The mixture was stirred at
50–60 °C for 12 h with the exclusion of light. The obtained grey so-
lution was filtered through a pad of Celite and the filtrate was slowly
evaporated to precipitate the required product. The compound
was further purified by acetonitrile–dichloromethane to give a crys-
talline solid. Single crystals suitable for X-ray analysis were obtained
by the slow diffusion of diethyl ether into acetonitrile solution
2
3
2
2H, JHH =1.2Hz, JHH =11.0Hz, CH¼HHcis); 5.39 (dd, 2H, JHH
1
3
containing the complex. Yield 1.12 g (75%); m.p. 185–187 °C. H
=1.2Hz, JHH =17.0 Hz, CH¼CHHtrans); 6.05 (m, 2H, 2 × CH);
NMR (500 MHz, DMSO-d6, 298 K, δ, ppm): 1.50 (t, J =7.0Hz, 6H,
2 × CH3); 4.60 (q, J =7.0Hz, 4H, 2 × N–CH2–CH3); 5.22 (d, J =6.0Hz,
7.50–7.65 (m, 4H, benzimidazolium-H6/H7); 7.77–7.86 (m, 2H,
benzimidazolium-H8); 7.90–8.00 (m, 2H, benzimidazolium-H9). 13C
{1H} NMR (125 MHz, DMSO-d6, 298 K, δ, ppm): 14.90 (CH3); 23.7
(CH2); 29.3 (CH2); 43.0 (N–CH2); 50.7 (N–CH2–CH); 55.6 (–CH¼);
112.5 (benzimidazolium-CH6); 118.3 (benzimidazolium-CH7); 121.2
(benzimidazolium-CH8); 127.9 (benzimidazolium-CH9); 179.7,
180.6 ((d, 1 J(C–109Ag) =199.5Hz and d, 1 J(C–107Ag) =185.0 Hz).
FT-IR (KBr disc, cmꢀ1): ca 3100, 3045 ν(C–HAr); 2996, 2967 (C–Haliph);
2
3
4H, 2 × N–CH2–CH); 5.36 (dd, 2H, JHH =1.5Hz, JHH =10.2Hz,
CH¼HHcis); 5.45 (dd, 2H, 2JHH =1.5 Hz, 3JHH =17.2 Hz, CH¼CHHtrans);
6.02 (m, 2H, 2 × CH); 7.50–7.65 (m, 4H, benzimidazolium-H6/H7);
7.77–7.86 (m, 2H, benzimidazolium-H8); 7.90–8.00 (m, 2H,
benzimidazolium-H9). 13C{1H} NMR (125 MHz, DMSO-d6, 298K, δ,
ppm): 48.7 (N–CH2–CH); 50.7 (–CH¼); 112.5 (benzimidazolium-CH6);
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Appl. Organometal. Chem. (2014)