Article
Organometallics, Vol. 29, No. 6, 2010 1427
yields 9.199 g (13.4 mmol, 67%) of Li[B(C6F5)4] as a colorless
solid. Mp: 253 ꢀC (dec). Anal. Calcd (found): C, 42.02 (41.58); H,
0.00 (0.11). 11BNMR (25ꢀC, C6D6, 96.3MHz):δ -16.4. 13C{1H}
NMR (25 ꢀC, C6D6, 75.5 MHz): δ 123 (br, ipso-C), 137.3 (dm, m-
1J(13C-19F) = 239 Hz). 19F{1H} NMR (25 ꢀC, CD2Cl2, 282.4
1
MHz): δ -165.7 (m, m-CF, J(13C-19F) = 245 Hz), -161.8
(dm, p-CF, 1J(13C-19F) = 247 Hz), -131.2 (dm, o-CF,
1J(13C-19F) = 239 Hz).
Synthesis of Silver Tetrakis(pentafluorophenyl)borate Toluene
1
CF, J(13C-19F) = 246 Hz), 139.2 (dm, p-CF, 1J(13C-19F) =
1
251 Hz), 148.6 (dm, o-CF, J(13C-19F) = 238 Hz). 19F{1H}
Solvate, Ag[B(C6F5)4] 2 Toluene. Silver tetrakis(pentafluorophenyl)-
3
NMR (25 ꢀC, C6D6, 282.4 MHz): δ -164.1 (m, m-CF, 1J-
borate diethyl etherate, Ag[B(C6F5)4] Et2O (1.722 g, 2 mmol), is
3
1
(13C-19F) = 246 Hz), -158.7 (dm, p-CF, J(13C-19F) = 251
dissolved in toluene (20 mL) at ambient temperatures, resulting in
a colorless, oily outer layer and a colorless, clear upper layer.
Removal of solvent results in a colorless solid, which is dried in
vacuofor five hours at 50ꢀC. The resulting residue isdissolved ina
minimum of hot toluene and cooled to ambient temperature over
a period of 10 hours, resulting in the deposition of colorless
crystals. The supernatant isremoved, andthe crystalline residueis
washed with n-pentane (5 mL) and dried in vacuo for five hours at
Hz), -134.9 (dm, o-CF, 1J(13C-19F) = 238 Hz). Recrystalliza-
tion from toluene gives Li[B(C6F5)4] 2 toluene. Prolonged ex-
3
posure to vacuum at elevated temperatures leads to a complete
loss of the two toluene molecules.
Synthesis of Lithium Tetrakis(pentafluorophenyl)borate Die-
thyletherate, Li[B(C6F5)4] Et2O. To a stirred solution of C6F5Br
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(10.13 g, 41 mmol) in diethyl ether (200 mL) is added dropwise
n-BuLi (2.5M, 16.4 mL, 41 mmol) at -80 ꢀC over a period of
5 min. The resulting colorless suspension is stirred for 30 min at
this temperature. A suspension of B(C6F5)3 (20.48 g, 40 mmol)
in diethyl ether (100 mL) is then added by means of PTFE tubing
in one portion. The resulting colorless suspension is stirred
for a further 10 min at this temperature and is then slowly
warmed to ambient temperatures over a period of one hour. The
solvent is removed in vacuo, resulting in a colorless, crystalline
residue, which is washed two times with 100 mL portions of
n-pentane and dried in vacuo (this crude product contains about
2.5 molecules of diethyl ether and shows a melting point of
120 ꢀC). The crystalline residue is then slowly heated to 120 ꢀC in
vacuo, which yields 29.92 g (39.4 mmol, 98%) of Li[B-
50 ꢀC, which yields 1.616 g (1.66 mmol, 83%) of Ag[B(C6F5)4] 2
3
toluene as a microcrystalline solid. Mp: 94 ꢀC (dec). Anal. Calcd
(found): C, 47.00 (46.46); H, 1.66 (1.73). 1H NMR (25 ꢀC,
CD2Cl2, 250.13 MHz): δ 2.39 (s, 3H, CH3), 6.8-7.7 (m, 5H,
CH-aryl). 11B{1H} NMR (25 ꢀC, CD2Cl2, 80.3 MHz): δ -16.6.
13C{1H} NMR (25 ꢀC, CD2Cl2, 62.9 MHz): δ 21.8 (s, CH3,
toluene), 123.1 (s, p-CH, toluene), 124 (br, ipso-C), 127.2 (s,
CH, toluene), 129.8 (s, CH, toluene), 136.9 (dm, m-CF,
1
1J(13C-19F) = 244 Hz), 138.9 (dm, p-CF, J(13C-19F) = 244
Hz), 114.5 (s, ipso-C, toluene), 148.8 (dm, o-CF, 1J(13C-19F) =
236 Hz). 19F{1H} NMR (25 ꢀC, CD2Cl2, 282.4 MHz): δ -167.4
(m, m-CF, 1J(13C-19F) = 244 Hz), -163.4 (dm, p-CF,
1J(13C-19F) = 244 Hz), -133.3 (dm, o-CF, 1J(13C-19F) =
236 Hz).
(C6F5)4] Et2O as a colorless solid. Mp: 184 ꢀC. Anal. Calcd
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(found): C, 44.24 (44.06); H, 1.33 (1.47). 1H NMR (25 ꢀC,
Synthesis of Pentafluorophenyl Silver, AgC6F5. Lithium
tetrakis(pentafluorophenyl)borate, Li[B(C6F5)4] (6.859 g, 10
mmol), and silver fluoride (1.649 g, 13 mmol) were combined
and suspended in dichloromethane (60 mL). The resulting
orange-colored suspension was sonicated in an ultrasonic bath
at 40-60 ꢀC for eight hours. The resulting grayish suspension is
filtered (F5), resulting in a brownish, clear solution. The solvent
is removed in vacuo, and the resulting pale brownish solid is
redissolved in n-hexane (30 mL), filtered (F4), and washed four
times by repeated back distillations of solvent. Removal of
solvent and drying in vacuo yields 2.461 g (8.95 mmol, 90%) of
pure Ag[B(C6F5)4] as an off-white solid. Mp: 276 ꢀC. Anal.
Calcd (found): C, 26.21 (25.89); H, 0.00 (0.00). 13C{1H} NMR
(25 ꢀC, CD3CN, 62.9 MHz): δ 121.7 (br, ipso-C), 137.0 (dm,
m-CF, 1J(13C-19F) = 252 Hz), 140.1 (dm, p-CF, 1J(13C-
19F) = 244 Hz), 150.0 (dm, o-CF, 1J(13C-19F) = 221 Hz).
19F{1H} NMR (25 ꢀC, CD3CN, 282.4 MHz): δ -163.1 (m, m-
CF), -159.1 (dm, p-CF), -106.5 (dm, o-CF). 19F{1H} NMR
(25 ꢀC, CD2Cl2, 282.4 MHz): δ -158.3 (m, m-CF), -143.8 (br,
p-CF), -100.4 (dm, o-CF). Recrystallization from CH3CN gives
3
CD2Cl2, 300.13 MHz): δ 1.17 (t, 6H, CH3, J(1H-1H) = 7.1
Hz), 3.64 (q, 4H, CH2, 3J(1H-1H) = 7.1 Hz). 11B NMR (25 ꢀC,
CD2Cl2, 80.3 MHz): δ -16.6. 13C{1H} NMR (25 ꢀC, CD2Cl2,
62.9 MHz): δ 14.4 (s, CH3), 67.5 (s, CH2), 123.1 (br, ipso-C),
1
137.4 (dm, m-CF, J(13C-19F) = 244 Hz), 139.3 (dm, p-CF,
1J(13C-19F) = 249 Hz), 148.8 (dm, o-CF, 1J(13C-19F) =
239 Hz). 19F{1H} NMR (25 ꢀC, CD2Cl2, 282.4 MHz):
δ -165.7 (m, m-CF, 1J(13C-19F) = 244 Hz), -160.8 (dm,
p-CF, 1J(13C-19F) = 249 Hz), -135.5 (dm, o-CF, 1J-
(13C-19F) = 239 Hz). The residual equivalent of diethyl ether
may be removed by dissolution of Li[B(C6F5)4] Et2O in
3
excess toluene, removal of solvent, and drying for five hours
at 60 ꢀC in vacuo.
Synthesis of Silver Tetrakis(pentafluorophenyl)borate Diethyl
Etherate, Ag[B(C6F5)4] Et2O. To a stirred solution of lithium
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tetrakis(pentafluorophenyl)borate diethyl etherate, Li[B-
(C6F5)4] Et2O (7.601 g, 10 mmol), in diethyl ether (80 mL) is
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added ddropwise a solution of AgNO3 (3.397 g, 20 mmol) in
H2O (20 mL, acidified with a few drops of HNO3(conc)) at
ambient temperatures, resulting in a colorless, clear aqueous
layer and a colorless, clear diethyl ether layer. The mixture is
shaken in a separation funnel and the ethereal layer is separated
and washed again with H2O (10 mL). The solvent is removed in
vacuo, resulting in a pale brown residue, which is dried at 60 ꢀC
for two hours in vacuo. The resulting brownish solid is dissolved
in dichloromethane (10 mL) and filtered (F4), resulting in a
clear, colorless solution. Removal of solvent and drying in vacuo
for three hours at 50 ꢀC yields 8.206 g (9.53 mmol, 95%) of
AgC6F5 (CH3CN).
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Recovering of B(C6F5)3. The washing solutions from the
synthesis of Li[B(C6F5)4] and AgC6F5 contain mainly B(C6F5)3,
which is recovered by sublimation at 110 ꢀC for six hours (cf.
3.2). This procedure yields about 73% of the possible quantity of
B(C6F5)3 as a colorless solid, which can directly be used for
further syntheses.
Acknowledgment. Financal support by the Deutsche
Forschungsgemeinschaft (SCHU 1170/4-1) is gratefully
acknowledged.
Ag[B(C6F5)4] Et2O as a colorless microcrystalline solid. Mp:
3
117 ꢀC (dec). Anal. Calcd (found): C, 39.06 (39.77); H, 1.17
1
(1.80). H NMR (25 ꢀC, CD2Cl2, 300.13 MHz): δ 1.30 (t, 6H,
CH3, 3J(1H-1H) = 7.0 Hz, 1J(13C-1H) = 126.4 Hz), 3.69 (q,
4H, CH2, 3J(1H-1H) = 7.0 Hz, 1J(13C-1H) = 144.0 Hz). 11
B
Supporting Information Available: Crystallographic data in
CIF data format. The CIF files are also available online from the
Cambridge Crystallographic Data Centre (CCDC Nos.
757606-757610). This material is available free of charge via
NMR (25 ꢀC, CD2Cl2, 96.3 MHz): δ -14.7. 13C{1H} NMR
(25 ꢀC, CD2Cl2, 75.5 MHz): δ 16.0 (s, CH3), 68.2 (s, CH2), 124.8
1
(br, ipso-C), 136.9 (dm, m-CF, J(13C-19F) = 245 Hz), 138.8
(dm, p-CF, 1J(13C-19F) = 247 Hz), 148.7 (dm, o-CF,