Journal of Inorganic and General Chemistry
www.zaac.wiley-vch.de
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
1
yield) was isolated from the crude reaction mixture by crystallization
temperature to –20 °C. M.p. 205–209 °C (dec). H NMR (500 MHz,
]acetonitrile): δ = 7.76 (s, 2 H), 1.55 (s, 18 H). 1 C NMR
(125.8 MHz, [D ]acetonitrile): δ = 148.45, 137.91, 133.72, 120.69,
114.92, 113.80, 122.88, 111.92, 104.86, 103.64, 99.96, 64.01, 29.89.
3
from MeCN at –26 °C, producing red X-ray quality crystals. M.p. [D
3
1
2
2
00 °C (dec, black). H NMR (500 MHz, [D
H), 7.68 (s, 2 H), 1.80 (s, 18 H), 1.52 (s, 18 H). H NMR (500 MHz,
]dichloromethane): δ = 7.52 (s, 2 H), 7.46 (s, 2 H), 1.86 (s, 18 H),
.57 (s, 18 H). 13C NMR (125.8 MHz, [D
]acetonitrile): δ = 30.00, 3152.08 (w, CH
0.10, 65.70, 66.28, 101.03, 114.25, 115.53, 116.72, 119.17, 120.53, CN), 2206.17 (w, CN), 1574.59 (w), 1433.82 (s) cm .
21.06, 122.48, 131.07, 140.19, 141.33, 152.40, 159.11. C17
3
]acetonitrile): δ = 7.79 (s,
3
1
+
[D
2
MS-FAB (M+H
2
+H ) = 375.21. FT-IR (KBr): ν˜ = 3186.79 (w, CH
3
),
1
3
1
3
3
), 3007.44 (w, CH ), 2989.12 (w, CH ), 2223.52 (s,
3
3
–
1
6 20
H N :
calcd. C 66.21; H 6.54; N 27.28%; found: C 65.79; H 6.90; N 27.46%.
Synthesis of Amidinium Salt 8: An oven-dried 300 mL triple-neck
round-bottomed flask equipped with a dry-ice condensor, stir bar, inlet
gas bubbler, and thermometer was setup. The dry-ice condensor outlet
was fitted to one end of an in-line oil bubbler with “T” and negative
pressure catch, and the other end was fitted to a nitrogen line with a
slow stream of nitrogen. The inlet gas bubbler was connected to a
cylinder of cyanogen via a 1/16ЈЈ coiled flexible polypropylene tubing
General Procedure for the Addition of 2a,b to 1: Within the drybox,
a solution of carbene (0.1–0.2 m) in THF was prepared in a Schlenk
flask equipped with a rubber septum. A second Schlenk flask of TCNE
in THF (0.1–0.2 m) equipped with a rubber septum and stir bar was
prepared within the drybox. The flasks were transferred outside of the
drybox, placed in an inert nitrogen atmosphere, and cooled to –70 °C
in a dry ice/acetone bath. The carbene solution was added dropwise to
the TCNE solution by syringe. After complete addition, the reaction
flask was slowly left to warm to room temperature. The solvent was
evaporated in vacuo and the solids that remained were further sepa-
rated by column chromotography on silica gel.
(
40 cm in linear length). This coiled connection tubing allowed for
tensionless weighing of the attached gas cylinders. The amount of cy-
anogen condensed in the reaction vessel was determined by mass loss
from the cylinder. Dry diethyl ether (100 mL) was placed in the
300 mL reaction flask and cooled to –78 °C by a dry ice/2-propanol
bath. Cyanogen (11.1 g, 214 mmol) was slowly condensed into the
cold diethyl ether. After the condensation of the cyanogen was com-
plete, the cyanogen cylinder was detached from the tubing, and the
tubing back-purged with dry nitrogen to remove any residual cyanogen
from the transfer system. Next, a cylinder of ammonia was connected
Isolation of 4a: The reaction of carbene 2a (0.250 g, 1.37 mmol) and
TCNE (0.176 g, 1.38 mmol) yields 4a (0.100 g, 0.243 mmol, 18%
yield) as a gold-yellow solid. 4a can be isolated from the crude reac-
tion mixture by chromatography on neutral silica gel in air using a 5%
to the system and, as with the cyanogen, was NH
3
(4.80 g,
MeCN/CH
2 2
Cl eluent. X-ray quality gold irregular-block crystals of
282.3 mmol) condensed into the cyanogen/ether solution at –78 °C.
4
a can be grown by heating and cooling a saturated DMSO solution.
After the addition of the ammonia was complete the ammonia cylinder
was disconnected from the setup and the connecting tubing was again
back-purged with dry nitrogen to remove residual ammonia from the
delivery lines. The ether solution of cyanoamidine and ammonia was
stirred for an additional 10 min at –78 °C and then cooled to –90 °C
1
H NMR (500 MHz, [D
6
]DMSO): δ = 8.38 (s, 2 H), 7.67 (s, 0.3 H),
.40 (s, 18 H). 13C NMR (125.8 MHz, [D
]acetonitrile): δ = 149.97,
47.44, 136.58, 131.47, 122.93, 116.12, 115.67, 112.87, 112.13,
11.55, 105.88, 85.03, 83.68, 64.39, 29.87.
1
1
1
3
2
by means of a liq. N /EtOH bath. A cylinder of dry HCl was connected
Isolation of 4b: The reaction of carbene 2b (0.336 g, 1.00 mmol) and
TCNE (0.128 g, 1.0 mmol) yields 4b (0.085 g, 0.15 mmol, 15% yield)
as a yellow solid. 4b can be isolated from the crude reaction mixture
by chromatography on neutral silica gel in air using a 10% MeCN/
to the system and at –90 °C HCl (10.3 g, 282.2 mmol) was slowly
condensed into the reaction vessel to avoid temperature excursions
and shifting the ammonia/cyanoamidine equilibrium. Protonations at
higher temperatures lead to formation of more ammonium chloride.
As the HCl was added the solution becomes light brown and copious
solids precipitate from the ether. The HCl cylinder was disconnected
from the system and the connecting tubing is back-purged with dry
nitrogen to remove residual HCl. The reaction suspension was allowed
to warm to room temperature and the solids collected by filtration
under nitrogen as a light brown solid and washed with 20 mL dry
ether. The crude product (25.3 g) is a 3:1 mixture of cyanoamidium
chloride, 8, and ammonium chloride. Recrystallization of crude solid
from 6N aq. HCl (ca. 40 mL) gave cyanoformamidinum chloride 8
2 2
CH Cl eluent. X-ray quality crystals of 4b can be grown by cooling
a saturated EtOAc solution from room temperature to –20 °C to afford
1
colorless crystals. M.p. Ͼ 250 °C. H NMR (500 MHz, [D
6
]DMSO):
δ = 8.47 (s, 2 H), 7.56 (s, 1 H), 2.08 (br., 6 H), 1.90 (m, 12 H), 1.60
m, 12 H). 1 C NMR (125.8 MHz, [D
3
(
6
]DMSO): δ = 149.85, 147.30,
1
8
36.57, 131.08, 116.32, 115.77, 113.08, 112.09, 111.93, 106.16, 84.66,
3.81, 65.69, 41.84, 34.99, 29.71.
Isolation of 5a: The reaction of carbene 2a (0.245 g, 1.36 mmol) and
TCNE (0.972 g, 6.81 mmol) yields 5a as a red solid. 5a can be isolated
from the crude reaction mixture by chromatography on neutral silica
(
16.2 g, mmol, 72%) as a beige solid. The freshly filtered product was
washed with 10 mL 8N aq. HCl and dried under a stream of dry nitro-
gen overnight. The isolated cyanoamidinium chloride was 99% pure
as indicated by H NMR spectroscopy. Brown solid (from 6N HCl),
gel in air using a 7.5% MeCN/CH
2 2
Cl eluent. X-ray quality red crys-
tals of 5a can be grown by heating and cooling a saturated DMSO
1
1
solution. M.p. 211–214 °C (dec). H NMR (500 MHz, [D
3
]acetonitr-
ile): δ = 7.77 (s, 2 H), 1.52 (s, 18 H). 1 C NMR (125.8 MHz, [D
3
mp. 154–190 °C (in a nitrogen atmosphere, dec, black) [mp. 150–
3
]ace-
tonitrile): δ = 136.57, 135.95, 132.28, 120.97, 112.67, 112.35, 111.36,
10.95, 107.73, 105.86, 96.52, 64.26, 29.74. FT-IR (KBr): ν˜ = 3190.65
w, CH ), 3163.65 (w, CH ), 3007.44 (w, CH ), 2938.98 (w, CH ),
228.34 (s, CN), 2210.49 (w, CN) 2209.06 (s, CN), 2204.24 (w, CN),
[
7]
1
1
NH
1
2
6
70 °C (dec)], H NMR (500 MHz, [D ]DMSO): δ = 10.71 (br. s,
1
3
). C NMR (125.8 MHz, [D
6
]DMSO): δ = 141.2 (q, C(NH
2
2
) ),
),
1
2
1
5
09.7 (q, CN). N NMR (50.7 MHz, [D ]DMSO): δ = 104.9 (NH
48.5 (CN). FT-IR (KBr): ν˜ = 3221 (m), 2986 (s), 2778 (w), 2728
6
2
(
3
3
3
3
2
1
–1
(w), 2678 (w), 2260 (vw), 2236 (vw), 2126 (vw), 1698 (vs), 1684 (vs),
599 (vw), 1579 (vw), 1473 (m), 1397 (m), 1145 (w), 902 (w), 702
582.31 (w), 1441.53 (s) cm .
1
–
1
Isolation of 6a: The reaction of carbene 2a (0.500 g, 2.78 mmol) and
TCNE (0.434 g, 3.39 mmol, 1.22 equiv.) yields 6a (0.172 g,
(m), 664 (w), 594 (w), 485 (m), 475 (m) cm .
0
.46 mmol, 17% yield) as an orange solid. 6a can be isolated from the
crude reaction mixture by chromatography on neutral silica gel in air
using a 7.5% MeCN/CH Cl eluent. X-ray quality crystals of 6a can
Synthesis of 11a: In a 20 mL round flask with a T-shaped glass tube,
a solution of sodium cyanotetrazolide (100 mg, 0.840 mmol), 1,3,5-
trimethylaniline hydrochloric acid salt (146 mg, 0.840 mmol) in 1,3,5-
trimethylaniline (1 mL) was stirred at 80 °C for 7 d in a nitrogen flow.
2
2
be grown by cooling a saturated 1:1 MeCN/toluene solution from room
Z. Anorg. Allg. Chem. 2015, 2190–2198
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