Organometallics
Article
(NCHN(Im)). FAB MS: m/z 169.137 [M]+ of cation (experimental),
169.134 [M]+ (calculated).
it difficult to know how many waters of recrystallization are present, or
if the sample crystallized without water in the lattice, and this can alter
the analytical results). See spectra in Figures SI-5−SI-8 (Supporting
Information.)
Synthesis of 3-Ethyl-1-pentylimidazolium Bromide (3).
Compound 3 was synthesized using a method similar to that described
for 1 using 1-ethylimidazole (5.000 g, 52.01 mmol) and bromopentane
(7.865g, 52.07 mmol). 3-Ethyl-1-pentylimidazolium bromide (3) was
obtained as a yellow, sticky oil in 90% yield (11.620 g, 47.22 mmol).
Synthesis of ImEt,CH2CH2OEtRu(Cl)2(C6Me6) (6). Compound 6 was
synthesized by a method similar to that described for 4 using 1 (0.135
g, 0.544 mmol), Ag2O (0.065, 0.280 mmol), and [RuCl2(C6Me6)]2
(0.176g, 0.271 mmol). The product was purified by recrystallization
through dissolving in hot toluene and placing in the freezer at −35 °C.
The product was purified by recrystallization from dichloromethane
a n d h e x a n e s a t r o o m t e m p e r a t u r e t o p r o d u c e
ImEt,CH2CH2OEtRuCl2(C6Me6) (6) as an orange solid in 69% yield
3
1H NMR (CDCl3, 500 MHz): δ 0.52 (t, 3H, CH3, JH−H = 7.5 Hz),
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0.98 (m, 4H, 2 × CH2(pentyl)), 1.26 (t, 3H, CH3, JH−H = 7.5 Hz),
1.59 (q, 2H, CH2(pentyl), 3JH−H = 7.0 Hz), 4.02 (t, 2H, NCH2, 3JH−H
= 7.5 Hz), 4.11 (q, 2H, NCH2, 3JH−H = 7.0 Hz), 7.33 (d, 1H, CH(Im),
3
3JH−H = 1.0 Hz), 7.49 (d, 1H, CH(Im), JH−H = 1.5 Hz), 9.99 (s, 1H,
1
CH(Im)); 13C NMR (CDCl3, 75 MHz): δ 12.90, 14.89 (2 × CH3),
21.05, 27.23, 29.05, 44.20, 48.94 (5 × CH2), 121.49, 121.55 (2 ×
CH(Im)), 135.19 (NCHN(Im)). CI MS: m/z = 167.155595 [M]+ of
cation (experimental), 167.154824 [M]+ of cation (calculated).
Synthesis of ImEt,CH2CH2OEtRuCl2(benzene) (4). A mixture of 1
(0.201g, 0.810 mmol) and Ag2O (0.110, 0.473 mmol) in 20 mL of
dichloromethane was stirred overnight under the exclusion of light.
The solution was filtered, and [RuCl2(benzene)]2 (0.204 g, 0.408
mmol) was added to the filtrate. The contents were further stirred for
20 h at room temperature. A white precipitate formed during the
reaction, which was filtered off, and the solvent from the filtrate was
dried under vacuum, leaving a dark orange solid, which was washed
with 10 mL of hexanes and then dried under vacuum. The product was
purified by recrystallization through dissolving in hot toluene and
placing in a freezer at −35 °C. Crystals suitable for X-ray diffraction
were grown by layering a dichloromethane solution with diethyl ether
and storing at −35 °C to produce ImEt,CH2CH2OEtRuCl2(benzene) (4)
(0.188 g, 0.371 mmol). H NMR (CDCl3, 500 MHz): δ 1.17 (t, 3H,
CH3(OEt), 3JH−H = 7.0 Hz), 1.44 (t, 3H, CH3(NEt), 3JH−H = 6.5 Hz),
1.98 (s, 18H, C6Me6), 3.46 (br, 2H, OCH2), 3.74 (br, 2H, OCH2),
3.85 (m, 2H, NCH2), 4.64−4.85 (m, 2H, NCH2), 6.99 (s, 2H,
CH(Im)), 7.43 (s, 1H, CH(Im)). 13C NMR (CDCl3, 75 MHz): δ
15.54, 15.78, 17.35 (3 × CH3), 46.05, 51.36, 66.60, 72.14 (4 × CH2),
93.88 (benzene), 121.15, 124.15 (2 × CH(Im)), 176.82(Ccarbene-Ru).
IR (ν, cm−1): 2931, 2875(C−H sp3), 1431, 1408, 1393, 1376, 1344,
1248, 1217, 1197, 1167 (weak), 1110, 968 (weak), 949 (weak), 922
(weak), 804, 729, 712 (weak), 691. CI MS: m/z 502.107973 [M]+
(experimental), 502.109167 [M]+ (calculated). Anal. Calcd for
C21H34ON2Cl2Ru: C, 50.20; H, 6.82; N, 5.58. Found: C, 50.89; H,
6.92; N, 5.50. See spectra in Figures SI-9−SI-12 (Supporting
Information).
Synthesis of RuCl(methylenebis(ImEt)2)(η6-p-cymene)]PF6 (7).
Compound 7 was synthesized using a slightly modified literature
procedure.40 A mixture of methylenebis(N-ethyl)imidazolium diiodide
(2.715 g, 5.888 mmol), Ag2O (3.382 g, 14.72 mmol), and 100 mL of
distilled water was mixed at room temperature with the exclusion of
light for 30 min. A dark gray mixture formed, which was filtered
through Celite to afford a clear solution. An aqueous solution of
NH4PF6 (6.862 g, 42.10 mmol) was added to the filtrate to instantly
produce a white precipitate. The precipitate was collected by vacuum
filtration and washed with distilled water (2 × 320 mL) and diethyl
ether (2 × 200 mL). The product was dried under vacuum. The
formation of the silver NHC salt was verified by 1H NMR in DMSO-
d6. The yield of [AgImethylenebis(N-ethylIm)2]PF6 was 1.591 g (3.489
mmol), and the percent yield was 59%.
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as a dark orange solid in 68% yield (0.231 g, 0.552 mmol). H NMR
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(CDCl3, 500 MHz): δ 1.17 (t, 3H, CH3(OEt), JH−H = 7.2 Hz), 1.42
(t, 3H, CH3(NEt), 3JH−H = 7.2 Hz), 3.47 (m, br, 2H, OCH2), 3.71 (m,
br, 2H, OCH2), 4.22 (m, br, 1H, NCH2), 4.53 (m, br, 1H, NCH2),
4.57 (m, br, 1H, NCH2), 4.61 (m, br, 1H, NCH2), 5.56 (s, 6H,
3
(benzene)), 7.05 (d, 2H, CH(Im), JH−H = 2.4 Hz), 7.31 (d, 1H,
3
CH(Im), JH−H = 2.4 Hz). 13C NMR (CDCl3, 75 MHz): δ 15.40,
17.02 (2 × CH3), 46.35, 51.77, 66.73, 70.88 (4 × CH2), 86.44
(benzene), 121.36, 122.97 (2 × CH(Im)), 171.73 (Ccarbene-Ru). IR (ν,
cm−1): 3102 (C−H aromatic), 2966, 2878 (C−H sp3), 1435, 1411,
1394, 1348, 1255, 1230, 1195 (weak), 1161 (weak), 1105, 1075, 1045,
921 (weak), 813, 740, 686. LIFDI MS: m/z 418.0 [M]+
(experimental), 418.3 [M]+ (calculated). FAB MS: m/z 383.046414
[M − Cl]+ (experimental), 383.045274 [M − Cl]+ (calculated). Anal.
Calcd for C15H22ON2Cl2Ru: C, 43.06; H, 5.30; N, 6.70. Found: C,
42.78; H, 5.10; N, 6.58. See spectra in Figures SI-1−SI-4 (Supporting
Information).
The silver carbene salt (1.554 g, 3.408 mmol), [(η6-p-cymene)-
RuCl2]2 (1.043 g, 1.703 mmol), and 100 mL of dichloromethane were
stirred at room temperature for 18 h. The orange mixture was then
filtered through Celite. The orange filtrate was collected, and the
volume was reduced to 20 mL. RuCl(methylenebis(N-ethylIm)2)(η6-
p-cymene)]+PF6− (7) precipitated as a yellow solid upon the addition
of 240 mL of diethyl ether. The product was collected by gravity
filtration and dried under vacuum to produce RuCl(methylenebis-
(ImEt)2)(η6-p-cymene)]PF6 (7) in 87% yield (1.834 g, 2.958 mmol).
Crystals suitable for X-ray crystallography were grown in methanol at
room temperature. 1H NMR (CDCl3, 500 MHz): δ 1.05 (d, 6H,
Synthesis of ImEt,CH2CH2OEtRuCl2(p-cymene) (5). Compound 5
was synthesized using a method similar to that described for 4 with 1
(0.209 g, 0.843 mmol), Ag2O (0.101 g, 0.436 mmol), and [RuCl2(p-
cymene)]2 (0.258 g, 0.421 mmol). The product was purified by
recrystallization through dissolving in hot toluene and placing in the
freezer at −35 °C. Crystals suitable for X-ray diffraction were grown by
dissolving in dichloromethane and layering with hexanes to produce
ImEt,CH2CH2OEtRuCl2(p-cymene)·0.9H2O (5·0.9H2O) as an orange
solid in 70% yield (0.281 g, 0.592 mmol).1H NMR (CDCl3, 500
3
3
CH3(iPr), JH−H = 6.5 Hz), 1.48 (t, 6H, CH3(NEt), JH−H = 7.0 Hz),
2.13 (s, 3H, CH3(cymene)), 2.43 (m, 1H, CH(iPr)), 4.32 (m, 2H,
CH2(NEt)), 4.48 (m, 2H, CH2(NEt)), 5.48 (d, 1H, NCH2N, 2JH−H
=
3
13.0), 5.59 (d, 2H, cymene, JH−H = 6.5 Hz), 5.64 (d, 2H, cymene,
3JH−H = 6.5 Hz), 6.10 (d, 1H, NCH2N, 2JH−H = 14.0 Hz), 7.12 (d, 2H,
3
MHz): δ 1.18 (t, 3H, CH3(OEt), JH−H = 7.0 Hz), 1.23 (d, 6H,
3
3
CH(Im), 3JH−H = 1.5 Hz), 7.33 (d, 2H, CH(Im), 3JH−H = 2.0 Hz). 13
C
CH3(iPr), JH−H = 6.5 Hz), 1.45 (t, 3H, CH3(NEt), JH−H = 7.0 Hz),
2.03 (s, 3H, CH3(cymene)), 2.91 (m, 1H, CH(iPr)), 3.48 (m, 2H,
OCH2), 3.71 (m, 2H, OCH2), 4.07−4.23 (m, 2H, NCH2), 4.73−4.80
(m, 2H, NCH2), 5.12 (d, 2H, cymene), 5.40 (d, 2H, cymene), 7.03 (d,
1H, CH(Im), 3JH−H = 2.0 Hz), 7.38 (d, 1H, CH(Im), 3JH−H = 2.0 Hz).
13C NMR (CDCl3, 75 MHz): δ 15.40, 17.05, 18.74, 22.76 (4 × CH3),
30.89 (CH(iPr)), 46.47, 51.80, 66.70, 71.25 (4 × CH2), 82.87, 85.14,
85.48, 99.81, 108.57 (cymene), 121.14, 123.33 (2 × CH(Im)), 173.82
(Ccarbene-Ru). IR (ν, cm−1): 3094 (C−H aromatic), 2958, 2864 (C−H
sp3), 1455, 1413, 1377, 1346, 1255, 1196 (weak), 1124, 1108, 1077,
1045, 928 (weak), 868, 802, 733, 710, 689; LIFDI MS: m/z 474.3
[M]+ (experimental), 474.4 [M]+ (calculated). Anal. Calcd for
C19H30ON2Cl2Ru: C, 48.10; H, 6.37; N, 5.90. Found: C, 47.35; H,
6.60; N, 5.83 (note that the hygroscopic nature of this molecule makes
NMR (CDCl3, 75 MHz): δ 16.4 (CH3(NEt)), 18.7 (CH3(iPr)), 22.8
(CH(iPr)), 32.1 (CH3(cymene)), 45.6 (CH2(NEt)), 61.6 (NCH2N),
91.8, 86.6 (2 × Ccym−H), 104.0, 108.4 (2 × Ccym-C), 122.3, 121.2 (2 ×
CH(Im)), 173.8 (Ccarbene-Ru). IR (ν, cm−1): 3100 (C−H aromatic),
2968 (C−H sp3), 1472, 1423, 1357 (weak), 1259, 1214, 1180, 1053
(weak), 725 (strong), 731, 697, 686. MS (ESI): [C21H30N4RuCl]+
calculated [M] m/z 475.1, experimental m/z [M] 475.1. IR (cm−1):
2968 (w), 3150 (w), 1472 (w), 1423 (w), 825 (s). Anal. Calcd for
C21H30N4ClF6PRu: C, 40.64; H, 4.88; N, 9.03. Found: C, 40.58; H,
4.64; N, 8.74. See spectra in Figures SI-13−SI-16 (Supporting
Information).
Synthesis of ImEt,PentylRuCl2(p-cym) (8). Compound 8 was
synthesized using a method similar to that described for 4 using 3
L
dx.doi.org/10.1021/om300547f | Organometallics XXXX, XXX, XXX−XXX