Synthesis and crystal structure of N-phenyl-N′-(pyridin-2-ylmethyl)-S-methyl-thiouronium iodide

Article abstract of DOI:10.1016/j.molstruc.2009.11.037

Methylation of N-phenyl-N′-(pyridin-2-ylmethyl)thiourea led to a new low melting thiouronium iodide salt, whereas a further methylation of the nitrogen of the pyridine ring was not successful. This could be explained by the inactivity of the nitrogen atom

Full text of DOI:10.1016/j.molstruc.2009.11.037

Journal of Molecular Structure 965 (2010) 50–55
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis and crystal structure of N-phenyl-N0-(pyridin-2-ylmethyl)-S-methyl-
thiouronium iodide
*
Anja Stojanovic , Cornelia Morgenbesser, Markus Galanski, Daniel Kogelnig, Alexander Roller,
Regina Krachler, Bernhard K. Keppler
University of Vienna, Department of Inorganic Chemistry, Waehringerstrasse 42, A-1090 Vienna, Austria
a r t i c l e i n f o
a b s t r a c t
Methylation of N-phenyl-N0-(pyridin-2-ylmethyl)thiourea led to a new low melting thiouronium iodide
salt, whereas a further methylation of the nitrogen of the pyridine ring was not successful. This could
be explained by the inactivity of the nitrogen atom due to the sterical shielding revealed by crystallo-
graphic data. Exchange of the iodide anion with bis(trifluoromethylsulfonyl)imide led to a thiouronium
room temperature ionic liquid. Methylation of the urea analog N-phenyl-N0-(pyridin-2-ylmethyl)urea
occurred on pyridine nitrogen, resulting in the expected pyridinium salt.
Article history:
Received 17 September 2009
Received in revised form 13 November 2009
Accepted 13 November 2009
Available online 20 November 2009
Keywords:
Ó 2009 Elsevier B.V. All rights reserved.
Thiouronium
Pyridinium
Urea
Ionic liquids
X-ray structure
1. Introduction
Following the idea of Rogers et al. [7], we have tried to synthe-
size similar compounds incorporating the urea and thiourea func-
Thiourea and urea compounds are widely applied in different
fields of chemistry e.g. as amine scavengers, in catalytic processes
or as germicides [1–3]. Moreover, they are very promising as metal
scavenger e.g. for Hg, Ag or Cu [4–6]. Recently Rogers et al. [7] ap-
pended different urea and thiourea functional groups onto the
imidazole ring, gaining interesting cations based on 1-alkyl-imi-
dazolium-3-alkyl(thio)urea structures. Combining these cations
with hexafluorophosphate as anion, they designed hydrophobic io-
nic liquids (ILs), which were liquid at room temperature and were
efficiently applied for the extraction of Cd(II) and Hg(II) from aque-
ous solutions [7]. Furthermore, Ignatyev et al. have reported ionic
liquids containing thiourea and urea moieties, suggesting their
possible application as solvents or catalysts [8,9].
Generally, ILs are defined as molten salts with a melting point
below 100 °C, mainly consisting of bulky and nonsymmetrical or-
ganic cations such as imidazolium, pyrrolidinium, pyridinium,
ammonium or phosphonium, whereas various inorganic or organic
anions are known. This group of compounds exhibits several out-
standing properties such as an extremely low vapor pressure or
extraordinary high thermal and electrochemical stabilities. Their
physico-chemical properties such as viscosity, hydrophobicity or
miscibility can be tuned by modifying the chemical structure of
their constituents [10].
tionality but with a pyridine ring, using N-phenyl-N0-pyridin
thiourea- and urea-based structures as starting materials. Several
structural studies of this group of substances have already been
presented in the literature and the influence of various substitu-
ents on inter- and intramolecular hydrogen bonding, and hence
on crystal packaging has been discussed in detail [11–14].
Herein, we present the simple methylation of N-phenyl-N0-
(pyridin-2-ylmethyl)thiourea
and
N-phenyl-N0-(pyridin-2-
ylmethyl)urea resulting in low melting salts with different
chemical structures. X-ray diffraction studies of the new thiouroni-
um iodide salt together with comprehensive NMR-experiments
were conducted and discussed. Anionic exchange of both low melt-
ing iodide salts with bis(trifluoromethylsulfonyl)imide led to a
room temperature thiouronium-based ionic liquid [8] and an
urea-based pyridinium salt.
2. Results and discussion
2.1. Synthesis
The starting material N-phenyl-N0-(pyridin-2-ylmethyl)thio-
urea 1 was prepared according to the literature [15]. Although
the sulfur atom is actually a weak acceptor in alkylation reactions,
it is well known that sulfur can act as extremely strong acceptor in
systems like R1R2C@S, where R1 and R2 can form an extended
* Corresponding author. Tel.: +43 1 4277 52625; fax: +43 1 4277 52620.
E-mail address: anja.stojanovic@univie.ac.at (A. Stojanovic).
0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2009.11.037

A. Stojanovic et al. / Journal of Molecular Structure 965 (2010) 50–55
51
delocalized system with C@S, as it is the case for thioureas and
thiosemicarbazones [16,17]. As expected, the methylation of com-
pound 1 with the twofold mol equivalent of iodomethane in ace-
tone resulted in the corresponding thiouronium compound 3
(Scheme 1). In contrast, methylation of the urea analog N-phe-
detected. In case of the methylated thiourea analog, most of the ex-
pected cross peaks in the HMBC NMR spectrum could not be ob-
served due to the very broad 1H NMR signals.
2.2. Crystal structure of N-phenyl-N0-(pyridin-2-ylmethyl)-S-methyl-
thiouronium iodide, 3
nyl-N0-(pyridin-2-ylmethyl)urea
2
resulted in N-phenyl-N0-(1-
methylpyridinium-2-ylmethyl)urea iodide 4. Even in highly
delocalized systems an oxygen atom is still a weak acceptor in
alkylation reactions [18–21]. Generally, methylation of starting
compounds N-phenyl-N0-(pyridin-2-ylmethyl)thiourea and the
urea analog resulted in the corresponding iodide salts, however,
with two different chemical structures (Scheme 1).
The difference in the methylation products of the thiourea and
urea precursors is clearly observable in 1H NMR spectra presented
in Fig. 1. Whereas the methylated thiourea compound generally
exhibited broad signals with the methyl group signal at 2.6 ppm,
the methylated urea compound is characterized by sharp signals;
the CH3 protons resonate at 4.3 ppm. Methylation of the pyridine
nitrogen in the urea compound was clearly confirmed by a long
range 1H, 13C HMBC NMR measurement. Shift correlation signals
of the N–CH3 protons with carbon atoms of the pyridine ring were
Beside the characteristic S–CH3 resonance at 2.6 ppm, the struc-
ture of the synthesized thiouronium iodide compound was further
confirmed by X-ray diffraction study, the result of which is shown
in Fig. 2. Crystal data and details of data collection are listed in Ta-
ble 1. Selected bond distances and angles along with hydrogen
bond parameters are given in Table 2. The conformation of the
compound is so, that the C6 of the phenyl ring and the S atom
are in anti position with respect to N1–C6 bond, whereas C8 and
the S atom are in syn position, with respect to N2–C8. This is in ac-
cord with the crystal structure of the starting compound, N-phe-
nyl-N0-(pyridin-2-ylmethyl)thiourea, already described in the
literature [11,12]. The formation of centrosymmetric dimers via
N2H hydrogen bonding to an iodide atom (N2–H2ꢀ ꢀ ꢀI1 3.483 Å)
of a neighboring pair of ions is evident in Fig. 3. In contrast, in
Scheme 1. Synthesis of salts. Reagents and conditions: (i) two mol equivalents of iodomethane, acetone, reflux at 70 °C, 24 h, inert atmosphere (ii) one mol equivalent of
lithium bis(trifluoromethylsulfonyl)imide, acetone/water, room temperature, over night.
Fig. 1. 1H NMR spectra of (a) starting compounds and (b) methylated products.

52
A. Stojanovic et al. / Journal of Molecular Structure 965 (2010) 50–55
Fig. 2. Thermal ellipsoid diagram for compound 3 showing intramolecular hydrogen bonding as well as N2Hꢀ ꢀ ꢀI1 bond with the iodide atom of the neighboring pair of ions,
with atom numbering scheme and displacement ellipsoids at 30% probability level.
Table 1
Table 2
Crystal data and details of data collection.
Selected bond distances (Å), bond angles (°) and hydrogen bond parameters.
Empirical formula
fw
C14H16N3SI
385.26
P21/c
7.2671(8)
13.0720(15)
16.432(2)
99.048(5)
1541.6(3)
4
Bond distances (Å)
Bond angles (°)
S1–C7
1.7482 (14)
1.8029 (14)
1.3236 (16)
1.4338 (16)
1.3293 (17)
1.4732 (17)
1.3883 (19)
1.3916 (19)
1.5114 (18)
1.3451 (17)
1.3899 (18)
1.3397 (18)
1.3888 (21)
C7–S1–C14
C6–N1–C7
C7–N2–C8
C2–C1–C6
C1–C2–C3
N1–C6–C1
N1–C6–C5
N1–C7–N2
S1–C7–N1
S1–C7–N2
N2–C8–C9
N3–C9–C13
C8–C9–N3
C8–C9–C13
C9–N3–C10
N3–C10–C11
102.24 (6)
125.57 (11)
124.76 (11)
119.29 (13)
120.25 (14)
120.56 (12)
118.46
120.49 (12)
118.20 (10)
121.22 (12)
115.66 (11)
122.26 (13)
115.94 (11)
121.70 (12)
118.18 (12)
123.19 (13)
Space group
a (Å)
b (Å)
c (Å)
b (°)
S1–C14
N1–C7
N1–C6
N2–C7
N2–C8
C1–C6
C1–C2
C8–C9
C9–N3
C9–C13
N3–C10
C10–C11
V (Å3)
Z
qcalcd (g/cmꢁ3
)
1.66
Crystal size (mm)
0.30 ꢂ 0.12 ꢂ 0.10
T (K)
120(2)
l
R1
(cmꢁ1
)
2.203
0.0195
0.0464
1.019
a
b
wR2
GOFc
a
b
c
R1
wR2 = {
GOF (goodness of fit) = {
=
R
||Fo| ꢁ |Fc||/
R|Fo|.
R
[wF2o ꢁ F2c Þ2]/
R
[wðF2oÞ2 ]}1/2
.
Hydrogen
bond
Bond distances (Å)
Bond angles (°) Symmetry code
R
[wFo2 ꢁ Fc2Þ2]/(n–p)}1/2, where n is the number of
reflections and p is the total number of parameters refined.
parameters
D–H
A
d (D–H) d (H. . .A) d (D. . .A) \DHA
case of different uncharged N-2-alkylpyridyl-N0-arylthioureas, this
kind of bond is built with the sulfur atom of a neighboring mole-
cule [13,14]. This structural difference is in accordance with the
second Etter hydrogen bonding rule, indicating the best hydrogen
bond donor and best hydrogen bond acceptor would preferably
form hydrogen bonds if there are no intramolecular hydrogen
bonds possible, e.g. due to sterical shielding [22]. An iodide anion
is clearly the better proton acceptor compared with a sulfur atom.
These two driving forces resulted in the 3D packing structure pre-
sented in Fig. 3. Due to the spatial dispersion of hydrogen bonding
and hence structure formation, the iodide anion is localized in the
neighborhood of the N2 atom. Additionally, the strong intramolec-
ular N1Hꢀ ꢀ ꢀN3 hydrogen bond (2.768 Å) resulted in the rigid struc-
ture of the pyridine ring, inhibiting a free rotation of the ring. Due
N1–H100 N3 0.880
N2–H200 I1 0.880
1.965
2.656
2.768 (12) 151.07
3.483 (17) 157.06
ꢁ1 + x, y, z
to the strong hydrogen bondings (and broad signals in NMR-exper-
iments) the N1H signal was not observable in 1H NMR spectra. This
rigid structure and strong hydrogen bondings make the N3 atom of
the pyridine ring practically ‘‘inactive” as electron donor. The at-
tempt of a further methylation of the thiouronium compound on
the nitrogen of the pyridine ring was not possible even under se-
vere experimental conditions. For example, a maximum of approx.
10% of a dually methylated compound was gained in a methylation
reaction of the thiouronium salt directly suspended in iodometh-
ane (30-fold excess) under reflux for several days.

A. Stojanovic et al. / Journal of Molecular Structure 965 (2010) 50–55
53
Fig. 3. Packing diagram for 3.
The prepared low melting iodide salts can strictly not be re-
garded as ionic liquids as they have melting points over 100 °C
(3: 133–135 °C; 4: 155–156 °C). However, a simple anion exchange
of iodide with bis(trifluoromethylsulfonyl)imide led to a significant
decrease in the melting points. While the pyridinium–urea com-
pound is solid at room temperature (melting point 104–105 °C),
the prepared thiouronium compound is liquid at room tempera-
ture and can be regarded as ionic liquid. Thiouronium ionic liquids
were already reported in the literature following different synthe-
sis routes [8,9,23,24], describing their outstanding properties and
possible application fields e.g. as solvents for synthetical and cata-
lytical reactions (Friedel–Crafts acylation and alkylation, Diels–Al-
der cycloadditions, esterifications), as electrolytes or surfactants
[8,24].
the solvent residual peak for 1H and 13C as internal reference. Ele-
mental analysis (C, H, N and S) was carried out by the Microanalyt-
ical Laboratory, University of Vienna [25]. ESI-MS-measurements
were performed with an Esquire3000 ion trap mass spectrometer
(Bruker Daltonics, Bremen, Germany) equipped with an orthogonal
ESI source. Samples were diluted with methanol to ensure good
spraying conditions and introduced via flow injection at a rate of
4 lL/min using a Cole-Parmer 74900 single-syringe infusion pump.
Infrared spectra were measured with a Bruker Vertex 70 FTIR spec-
trometer (4000–400 cmꢁ1). Melting points were determined with a
Melting Point B-540 instrument from Büchi, Switzerland.
4.2. The following procedure is representative of the synthesis of (1)
and (2) [15,18]
2-(Aminomethyl)pyridine was dissolved in dry dichlorometh-
ane and cooled to 0 °C (ice bath). An equimolar amount of phenyl-
isothiocyanate or phenylisocyanate, respectively, was slowly
added and stirred at room temperature over night. After evapora-
tion of the solvent, the solid product was dried under vacuum
(10ꢁ3 mbar) for 24 h.
3. Summary
In summary, we have shown that the methylation of N-phenyl-
N0-(pyridin-2-ylmethyl)thiourea occurred on the sulfur atom of the
thiourea group. Crystallographic data revealed that the nitrogen of
the pyridine ring is shielded due to the strong hydrogen bond and
is therefore not easily available for a further methylation. Anion
exchange led to a hydrophobic thiouronium room temperature io-
nic liquid. The methylation of the urea analog led to low melting
pyridinium salts.
4.2.1. N-phenyl-N0-(pyridin-2-ylmethyl)thiourea (1)
White solid, yield 98%; 1H NMR (500 MHz, DMSO-d6): d = 4.85
(d, J = 4.7 Hz, 2H), 7.14 (t, J = 7.3 Hz, 1H), 7.30 (t, J = 7.2 Hz, 1H),
7.37 (m, 3H), 7.51 (d, J = 7.6 Hz, 2H), 7.79 (t, J = 7.5 Hz, 1H), 8.29
(s, 1H), 8.54 (d, J = 4.6 Hz,1H), 9.88 (s, 1H) ppm. ESI-MS: m/z calcd
for C13H13N3S: 244.33 (+); 242.33 (ꢁ); found: 244.2 (+); 242.1 (ꢁ).
4. Experimental
IR: 3172, 2994–2800, 1591, 1518, 1422; 1239 and 840–500 cmꢁ1
.
4.1. General considerations
Anal. Calcd for C13H13N3S: C, 64.16; H, 5.39; N, 17.27; S, 13.18;
found: C, 64.21; H, 5.59; N, 17.36; S, 12.97.
Dichloromethane for synthesis was distilled over P2O5 before
use. All other chemicals were used as received without further
purification. 1H, 13C and two-dimensional HMBC NMR spectra were
recorded with a Bruker Avance III 500 MHz NMR spectrometer at
500.32 (1H) and 125.81 (13C), or 500.10 (1H) and 125.75 (13C)
MHz (standard Bruker pulse programs) in DMSO-d6 at 298 K, using
4.2.2. N-phenyl-N0-(pyridin-2-ylmethyl)urea (2)
White solid, yield 98%; 1H NMR (500 MHz, DMSO-d6): d = 4.42
(d, J = 5.7 Hz, 2H), 6.76 (t, J = 5.7 Hz, 1H), 6.90 (t, J = 7.3 Hz, 1H),
7.21–7.29 (m, 3H), 7.36 (d, J = 7.8 Hz, 1H), 7.43 (d, J = 7.8 Hz, 2H),

54
A. Stojanovic et al. / Journal of Molecular Structure 965 (2010) 50–55
7.78 (t, J = 7.8 Hz, 1H), 8.54 (d, J = 4.8 Hz, 1H), 8.77 (s, 1H) ppm. ESI-
MS: m/z calcd for C13H13N3O: 228.3 (+); 226.3 (ꢁ); found: 228.1
(+); 226.2 (ꢁ). IR: 3331, 3020–2900, 1631, 1624; 1594, 1568,
1440, 1239, 790–500 cmꢁ1. Anal. Calcd for C13H13N3O: C, 68.70;
H, 5.77; N, 18.49; found: C, 68.66; H, 5.57; N, 18.55.
J = 5.8 Hz, 1H), 7.27 (m, 2H), 7.43 (m, 2H), 7.99 (m, 2H), 8.55 (t,
J = 7.7 Hz, 1H), 8.98 (d, J = 5.0 Hz, 2H) ppm. 13C NMR (126 MHz,
DMSO-d6): d = 41.0, 45.7, 118.5, 118.7, 121.2, 122.3, 126.2, 126.6,
129.5, 140.3, 146.0, 147.0, 155.7, 157.4 ppm. ESI-MS: m/z calcd
for C16H16N4O5S2F6: 242.3 (+); 280.2 (ꢁ); found: 242.1 (+); 279.7
(ꢁ). IR: 3320, 3102–2950, 1650, 1567, 1597; 1517, 1447, 1348,
4.3. The following procedure is representative of the synthesis of (3)
and (4)
1188, 1135, 1057, 739, 780–500 cmꢁ1
.
Anal. Calcd for
C16H16N4O5S2F6: C, 36.78; H, 3.09; N, 10.73; S, 12.28; found: C,
36.83; H, 3.06; N, 10.71; S, 12.26.
General methylation route: starting material (1 oder 2, respec-
tively) was dissolved in acetone at 40 °C and a twofold mol equiv-
alent of iodomethane was slowly added. The reaction was refluxed
(70 °C, solvation of reactants at 50 °C) under inert atmosphere for
24 h. After evaporation of the solvent, the resulting solid was dried
under vacuum (10ꢁ3 mbar) for 24 h.
4.5. Crystallographic structure determination
A crystal suitable for X-ray diffraction measurements was ob-
tained after recrystallisation of compound 3 in acetone at 50 °C
and subsequently slowly evaporation of the solvent under cooling.
X-ray diffraction measurements were performed on a Bruker X8
4.3.1. N-phenyl-N0-(pyridin-2-ylmethyl)-S-methyl-thiouronium iodide
(3)
APEXII diffractometer with graphite-monochromated Mo K radia-
a
tion (k = 0.71073 Å), controlled by a Pentium-based PC running the
SAINT software package. A single crystal was positioned at 35 mm
from the detector and 1921 frames were measured, each for 30 s
over 1° scan for N-phenyl-N0-(pyridin-2-ylmethyl)-S-methyl-thio-
uronium iodide. Crystal data, data collection parameters and struc-
ture refinement details are given in Table 1. The structure was
solved by direct method and refined on F2 by full-matrix least-
squares techniques using the SHELXTL software package. All non-
hydrogen atoms were refined with anisotropic displacement
parameters. Hydrogen atoms were placed at calculated positions
or localized on difference Fourier maps and isotropically refined.
The graphics were prepared by using ORTEP24.
White solid, yield 80%; 1H NMR (500 MHz, DMSO-d6): d = 2.66
(s, 3H), 4.88 (s, 2H), 7.32–7.51 (m, 7H), 7.94 (s, 1H), 8.65 (s, 1H),
9.44 (s, 1H) ppm. 13C NMR (126 MHz, DMSO-d6): d = 14.9, 48.8,
122.7, 123.7, 126.8, 128.6, 130.1, 138.5, 149.1, 155.1 ppm. ESI-
MS: m/z calcd for C14H16N3SI: 258.4 (+); 126.9 (ꢁ); found: 258.1
(+); 126.8 (ꢁ). IR: 3105, 2977–2800, 1630; 1590, 1490, 1424;
1287, 760–570 cmꢁ1. Anal. Calcd for C14H16N3SI: C, 43.64; H,
4.19; N, 10.91; S, 8.32; found: C, 43.64; H, 4.32; N, 10.82; S, 8.09.
4.3.2. N-phenyl-N0-(1-methylpyridinium-2-ylmethyl)urea iodide (4)
White solid, yield 83%; 1H NMR (500 MHz, DMSO-d6): d = 4.35
(s, 3H), 4.76 (d, J = 5.6 Hz, 2H), 6.95 (t, J = 7.3 Hz, 1H), 7.02 (t,
J = 5.8 Hz, 1H), 7.26 (d, J = 7.8 Hz, 2H), 7.43 (d, J = 7.8 Hz, 2H), 8.01
(m, 2H), 8.56 (t, J = 7.5 Hz, 1H), 8.99 (br, 2H) ppm.13C NMR
(126 MHz, DMSO-d6): d = 41.1, 45.6, 118.5, 122.2, 126.1, 126.6,
129.2, 140.3, 145.7, 147.0, 155.6, 157.4 ppm. ESI-MS: m/z calcd
for C14H16N3OI: 242.3 (+); 126.9 (ꢁ); found: 242.1 (+); 126.8 (ꢁ).
IR: 3302; 3181, 3120, 3060–2900, 1689, 1624; 1597, 1542, 1441,
790–500 cmꢁ1. Anal. Calcd for C14H16N3OI: C, 45.54; H, 4.37; N,
11.38; found: C, 45.59; H, 4.19; N, 11.32.
Acknowledgments
The authors are grateful to Prof. Vladimir Arion, University of
Vienna, for his constructive criticism and review of the manuscript.
The financial support of the Austrian Federal Ministry of Agricul-
ture, Forestry, Environment and Water Management (Project No.
A600702) is gratefully acknowledged.
Appendix A. Supplementary data
4.4. The following procedure is representative of the synthesis of (5)
and (6) [8,24]
All measured NMR spectra as well as the synthesis route and
characterization of the dual methylation of N-phenyl-N0-(pyridin-
2-ylmethyl)-S-methyl-thiouronium iodide (3) can be found in the
supplementary data. Crystallographic data for the structure
reported in this paper have been deposited with the Cambridge
Crystallographic Data Center as supplementary publication No.
CCDC-747959. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.molstruc.2009.
11.037.
Iodide salts were dissolved in appropriate solvents (3 water; 4
water/acetone 1:1) and an equimolar amount of lithium bis(tri-
fluoromethylsulfonyl)imide dissolved in water was added. The
reaction mixture was stirred under inert atmosphere at room tem-
perature for 24 h. The hydrophobic phase formed was separated
and washed several times with ice-cold water. Products were dried
under vacuum at 40 °C for 24 h (10ꢁ3 mbar).
4.4.1. N-phenyl-N0-(pyridin-2-ylmethyl)-S-methyl-thiouronium
bis(trifluoromethylsulfonyl)imide (5)
References
Green liquid, yield: 73%; 1H NMR (500 MHz, DMSO-d6): d = 2.64
(s, 3H), 4.87 (br, 2H), 7.29–7.51 (m, 7H), 7.93 (s, 1H), 8.65 (s, 1H),
9.42 (br, 1H).13C NMR (126 MHz, DMSO-d6): d = 14.7, 48.8, 118.7,
121.2, 122.6, 123.7, 126.8, 128.6, 130.1, 138.5, 149.2, 155.3 ppm.
ESI-MS: m/z calcd for C16H16N4O4S3F6: 258.4 (+); 280.2 (ꢁ); found:
258.2 (+); 279.7 (ꢁ). IR: 3348, 3070–2900, 1595, 1495, 1348, 1196,
1137, 1059, 739, 780–500 cmꢁ1. Anal. Calcd for C16H16N4O4S3F6: C,
35.68; H, 3.00; N, 10.41; S, 17.86; found: C, 36.00; H, 3.07; N,
10.34; S, 17.82.
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4.4.2. N-phenyl-N0-(1-methylpyridinium-2-ylmethyl)urea
bis(trifluoromethylsulfonyl)imide (6)
White solid, yield: 80%, 1H NMR (500 MHz, DMSO-d6): d = 4.34
(s, 3H), 4.75 (d, J = 5.8 Hz, 2H), 6.95 (t, J = 7.5 Hz, 1H), 7.01 (t,

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