Structural, thermal and spectral studies of N-2-pyridyl-, N-2-picolyl- and N-2-(4,6-lutidyl)-N′-(3-methoxyphenyl)thioureas

Article abstract of DOI:10.1016/S0022-2860(02)00205-3

N-2-pyridyl-N′-3-methoxyphenylthiourea, PyTu3OMe, triclinic, P-1, a = 8.6590(16), b = 8.7489(16), c = 10.0540(15) ?, α = 90.255(9), β = 66.765(8), γ = 68.547(7)°, V = 641.40(19) ?³ and Z = 2; N-2-(3-picolyl)-N′-3-methoxyphenylthiourea, 3PicTu3OMe, triclinic, P-1, a = 6.9100(9), b = 12.7370(16), c = 16.4710(14) ?, α = 107.782(6), β = 91.656(7), γ = 95.115(4)°, V = 1372.5(3) ?³ and Z = 4; N-2-(4-picolyl)-N′-3-methoxphenylthiourea, 4PicTu3OMe, monoclinic, C2/c, a = 12.5036(7), b = 8.5942(5), c = 25.4050(10) ?, β = 97.712(3)°, V = 2705.3(2) ?³ and Z = 8; N-2-(5-picolyl)-N′-3-methoxyphenylthiourea, 5PicTu3OMe, monoclinic, P2₁/c, a = 10.9200(4), b = 15.3920(15), c = 8.1150(11) ?, β = 92.020(5)°, V = 1363.1(2) ?³ and Z = 4; N-2-(6-picolyl)-N′-3-methoxyphenylthiourea, 6PicTu4OMe, triclinic, P-1, a = 7.4220(16), b = 9.944(3), c = 10.038(3) ?, α = 104.815(9), β 94.452(16), γ = 108.134(14)°, V = 670.6(3) ?³ and Z = 2 and N-2-(4,6-lutidyl)-N′-3-methoxyphenylthiourea, 4,6LutTu3OMe, orthorhombic, Pbca, a = 16.3710(5), b = 7.4910(6), c = 24.1890(15) ?, V = 2966.4(3), Z = 8. Intramolecular hydrogen bonding between N′H and the pyridine nitrogen and intermolecular hydrogen bonding between NH and the thione sulfur are characteristic of these thioureas except that 3PicTu3OMe has a very weak intermolecular NH···S interaction due to a steric effect of the methyl group.

Full text of DOI:10.1016/S0022-2860(02)00205-3

Journal of Molecular Structure 613 (2002) 223–233
www.elsevier.com/locate/molstruc
Structural, thermal and spectral studies of N-2-pyridyl-,
N-2-picolyl- and N-2-(4,6-lutidyl)-N0-(3-methoxyphenyl)thioureas
James M. Giesen, Kacey A. Claborn, Karen I. Goldberg, Werner Kaminsky, Douglas
*
X. West
Department of Chemistry, 351700, University of Washington, Seattle, WA 98195-1700, USA
Received 13 August 2001; accepted 19 April 2002
Abstract
0
ꢀ
N-2-pyridyl-N -3-methoxyphenylthiourea, PyTu3OMe, triclinic, P-l, a ¼ 8:6590ð16Þ; b ¼ 8:7489ð16Þ; c ¼ 10:0540ð15Þ A;
0
ꢀ 3
a ¼ 90:255ð9Þ; b ¼ 66:765ð8Þ; g ¼ 68:547ð7Þ8; V ¼ 641:40ð19Þ A and Z ¼ 2; N-2-(3-picolyl)-N -3-methoxyphenylthiourea,
ꢀ
3PicTu3OMe, triclinic, P-1, a ¼ 6:9100ð9Þ; b ¼ 12:7370ð16Þ; c ¼ 16:4710ð14Þ A; a ¼ 107:782ð6Þ; b ¼ 91:656ð7Þ; g ¼
0
ꢀ 3
95:115ð4Þ8; V ¼ 1372:5ð3Þ A and Z ¼ 4; N-2-(4-picolyl)-N -3-methoxphenylthiourea, 4PicTu3OMe, monoclinic, C2/c, a ¼
12:5036ð7Þ; b ¼ 8:5942ð5Þ; c ¼ 25:4050ð10Þ A; b ¼ 97:712ð3Þ8; V ¼ 2705:3ð2Þ A and Z ¼ 8; N-2-(5-picolyl)-N 0-3-
ꢀ
ꢀ 3
ꢀ
methoxyphenylthiourea, 5PicTu3OMe, monoclinic, P21/c, a ¼ 10:9200ð4Þ; b ¼ 15:3920ð15Þ; c ¼ 8:1150ð11Þ A; b ¼
92:020ð5Þ8; V ¼ 1363:1ð2Þ A and Z ¼ 4; N-2-(6-picolyl)-N0-3-methoxyphenylthiourea, 6PicTu4OMe, triclinic, P-1, a ¼
ꢀ 3
ꢀ
ꢀ 3
7:4220ð16Þ; b ¼ 9:944ð3Þ; c ¼ 10:038ð3Þ A; a ¼ 104:815ð9Þ; b ¼ 94:452ð16Þ; g ¼ 108:134ð14Þ8; V ¼ 670:6ð3Þ A and Z ¼ 2
and N-2-(4,6-lutidyl)-N0-3-methoxyphenylthiourea, 4,6LutTu3OMe, orthorhombic, Pbca, a ¼ 16:3710ð5Þ; b ¼ 7:4910ð6Þ; c ¼
0
ꢀ
24:1890ð15Þ A; V ¼ 2966:4ð3Þ; Z ¼ 8: Intramolecular hydrogen bonding between N H and the pyridine nitrogen and
intermolecular hydrogen bonding between NH and the thione sulfur are characteristic of these thioureas except that
3PicTu3OMe has a very weak intermolecular NH· · ·S interaction due to a steric effect of the methyl group. q 2002 Elsevier
Science B.V. All rights reserved.
Keywords: 2-Pyridylthioureas; 3-Methoxyphenylthioureas; Crystal structures; Hydrogen bonding; Enthalpy of fusion
1. Introduction
demonstrated that intermolecular N–H· · ·S hydrogen
bonding [2] also existed and resulted in dimer
formation. Both forms of hydrogen bonding, as well
as the planarity of the molecules, have been the focus
in recent structural studies of substituted N-(2-
pyridyl)-N 0-arylthioureas including N-(2-pyridyl)-
N0-tolylthioureas [3] and the N-2-(4,6-lutidyl)-N0-
tolylthioureas [4]. In addition, the structures of N-(5-
bromo-2-pyridyl)-N 0-2-(2,5-dimethoxyphenyethyl)
thiourea [5] and four thioureas with p-substituted aryl
groups including N-(2-pyridyl)-N 0-(4-methoxyphe-
nyl)thiourea [6], in which the methoxy oxygen is
Intramolecular hydrogen bonding between the
pyridine nitrogen and N0H for N-(2-pyridyl)thioureas
1
was confirmed some years ago by a H NMR study
[1]. More recently, the crystal structure of N-(2-
pyridyl)-N0-phenylthiourea also showed intramolecu-
lar N0-H· · ·N interaction in the solid state and
*
Corresponding author. Tel.: þ1-360-642-5813; fax: þ1-206-
685-8665.
E-mail address: westdx@hotmail.com (D.X. West).
0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-2860(02)00205-3

224
J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
Fig. 1. Representation of (a) N-2-pyridyl-N 0-3-methoxyphenylthiourea, (b) N-2-(n-picolyl)-N 0-3-methoxyphenylthioureas, (c) N-2-(4,6-
lutidyl)-N 0-3-methoxyphenylthiourea and (d) a representation showing the intermolecular NH· · ·S hydrogen bonding, as well as the potential
C3H· · ·S interaction.
also involved in weak intermolecular interactions,
have been reported. A study of the structural,
thermal and spectral properties of N-2-(picolyl)-
and N-(4,6-lutidyl)-N0-phenylthioureas has been
communicated [7]. A recent study showed that
some members of a series of N-(2-pyridyl)-N0-2-
methoxyphenylthioureas possess bifurcated intra-
molecular hydrogen bonding involving the pyridyl
nitrogen and methoxy oxygen [8]. Since the
methoxy substituent can add to the intermolecular
interactions, we decided to prepare and character-
ize a series of N-2-pyridyl-N0-3-methoxyphe-
nylthioureas. Included in this report are the X-
eas, Fig. 1, which are represented by the symbols
PyTu3OMe (a), 3PicTu3OMe (b), 4PicTu3OMe
(b), 5PicTu3OMe (b), 6PicTu3OMe (b) and
4,6LutTu3OMe (c).
2. Experimental
2.1. Preparative, spectral and thermal methods
3-Methoxyphenyl isothiocyanate and 2-aminopyri-
dine, the four 2-aminopicolines and 2-amino-4,6-
lutidine were purchased from Aldrich Chemical
Company, Milwaukee, WI, and used as received.
The desired 2-aminopyridine was mixed in a 1:1
molar ratio with 3-methoxyphenyl isothiocyanate in
1
ray crystal structures, DHfus and selected H NMR
spectral assignments of N-2-pyridyl-, the four N-2-
picolyl- and N-2-(4,6-lutidyl)-N0-3-methoxythiour-

J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
225
Table 6
Melting points (8C), DHfus values (kJ/mol) and selected 1H NMR peaks (ppm) for the various N-2 pyridyl-N0-3-methoxyphenylthioureas
Thiourea
M.p.
DHfus
N0H (N3H)
NH (N2H)
C6H
OCH3
CH3
PyTu3OMe
136–138
88–89
22.2
19.3
26.4
34.5
31.5
33.1
13.60
13.94
13.61
13.60
14.60
14.27
8.20
8.10
8.21
8.27
7.87
8.07
7.74
7.54
7.74
8.03
3.85
3.85
3.85
3.84
3.84
3.84
2.19
2.18
2.18
2.17
2.18
2.19
3PicTu3OMe
4PicTu3OMe
5PicTu3OMe
6PicTu3OMe
4,6LutTu3OMe
159–160
180–181
172–173
165–166
95% ethanol and the mixture stirred with gentle
warming for a minimum of 1 h. On cooling and
slowly evaporating the reactant mixture, the
thioureas crystallized from solution, were filtered
and washed with i PrOH. The yields are ca. 70%
for each of the thioureas and the melting points
are listed in Table 6 with the DHfus values. Their
1H NMR spectra were recorded in CDCl3 with a
Varian 300 MHz spectrometer and the enthalpies
of fusion were obtained with approximately 3 mg
samples at a heating rate of 108/min using a
Perkin–Elmer Differential Scanning Calorimeter,
DSC7.
3. Results and discussion
3.1. Structural studies
The ORTEP drawings for the thioureas are shown
in Figs. 2–7 and bond distances and angles are listed
in Table 3. These thioureas crystallize with one
unique molecule per unit cell, except for 3Pic-
Tu3OMe, which has two crystallographically differ-
ent molecules. In a similar study of the 2-methoxy
analogues [8] we were not able to acquire a suitable
crystal
of
N-2-(3-picolyl)-N0-2-methoxyphe-
nylthiourea, 3PicTu2OMe, and only N-2-(6-picolyl)-
N0-2-methoxyphenylthiourea, 6PicTu2OMe, has two
crystallographically different molecules in the unit
cell in that series. Like other N-2-pyridyl-N0-
arylthioureas [2–8], the thioureas of this study are
found in a conformation resulting from intramolecular
hydrogen bonding of N3H (N0H) to the pyridine
nitrogen, N1, in a manner similar to the benzoyl and
acyl thioureas [13–20]. Some of these thioureas are
nearly planar (vide infra), but evidently the packing of
molecules causes 4PicTu3OMe to be unique in this
series; it has its methoxy group on the same side of the
molecule as the thione sulfur. This arrangement is also
different from N-2-(4,6-lutidyl)-N0-3-chlorophe-
nylthiourea, 4,6LutTu3Cl, which has its aryl ring
rotated so that the chloro substituent is on the opposite
side of the molecule from the thione sulfur. These
thioureas have essentially the same bond distances,
Table 3, except that the N3–C7 bond of PyTu3OMe is
2.2. X-ray data collection, structure solution and
refinement
Crystals of the thioureas were grown by slow
evaporation of 1:1 by volume acetone–ethanol
mixtures at room temperature. The colorless
thiourea crystals were mounted in random orien-
tation on a glass fiber and data acquired with a
Nonius Kappa CCD Diffractometer. The structures
were solved by direct methods and missing atoms
were found by difference-Fourier synthesis. The
non-hydrogen atoms were refined with anisotropic
temperature factors and hydrogens attached to
nitrogens and carbons, except for methyl groups,
were found on a difference Fourier map and
refined isotropically. Scattering factors are from
Wassmaire and Kirfel [9], calculations were done
by maXus, version 2.0 [10], structure refinement
for the three thioureas was carried out with
SHELXL-97 [11] and the graphics used are Zortep
[12]. Tables 1 and 2 summarize the crystal data,
collection information and refinement data for
these thioureas.
˚
substantially shorter, 1.305(5) A, than the analogous
bond for the other thioureas of this study. There is a
greater difference in the bond angles; for the various
molecules some angles involving the thiourea moiety
differ by 4–58, Table 3.
The intramolecular hydrogen bonding parameters,

226
J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
Table 1
Crystallographic data and methods of data collection, solution and refinement for PyTu3OMe, 3PicTu3OMe and 4PicTu3OMe
Crystal data
PyTu3OMe
13HI3ON3S
3PicTu3OMe
C14H15ON3S
Pale yellow, prism
0.48 £ 0.31 £ 0.24
293(2)
4PicTu3OMe
C14(H15ON3S
Colorless, prism
0.48 £ 0.48 £ 0.41
293(2)
Empirical formula
Crystal color, habit
Crystal size (mm)
Temperature (K)
Crystal system
Space group
C
Colorless, prism
0.26 £ 0.12 £ 0.10
293(2)
Triclinic
Triclinic
Monoclinic
C2/c
P-1 (#2)
P-1 (#2)
˚
a (A)
˚
b (A)
˚
c (A)
8.6590(16)
8.7489(16)
10.0540(15)
90.255(9)
66.765(8)
68.547(7)
641.40(19)
2
6.9100(9)
12.5040(7)
8.5940(5)
25.4050(10)
90
12.7370(16)
16.4710(14)
107.782(6)
91.656(7)
a (8)
b (8)
g (8)
97.712(3)
90
95.115(4)
3
˚
Volume (A )
1372.5(3)
2705.3(2)
8
Z
4
Formula weight
259.32
273.35
273.35
Density (calcd) (g/cm3)
Absorption coefficient (mm21
Reflections for indexing
u range for data collection (8)
F(000)
1.343
1.323
1.342
)
0.244
0.231
0.235
152
489
182
4.15–21.96
272
3.54–21.96
576
3.24–28.30
1152
Index ranges
29 # h # 9
29 # k # 9
210 # l # 10
2078
27 # h # 6
213 # k # 13
217 # l # 16
5131
0 # h # 16
210 # k # 11
228 # l # 28
4584
Reflections collected
Inddpendent reflections, Rint
Completeness to u (%)
Absorption correction
Max. and min. transmissions
Goodness-of-fit
1032, 0.1068
83.6
3119, 0.0474
92.6
2928, 0.0285
40.7
HKL-SCALEPACK
0.9761 and 0.9394
0.948
HKL-SCALEPACK
0.9466 and 0.8971
0.990
HKL-SCALEPACK
0.9099 and 0.8957
1.049
23
˚
Largest diff. Peak, hole (eA
)
0.221, 20.186
0.0563, 0.1194
0.0930, 0.1337
0.271, 20.156
0.0542, 0.1332
0.0975, 0.1545
0.206, 20.201
0.0437, 0.1189
0.0704, 0.1315
R, wR2
R, wR2 (all reflections)
Table 4, for this series of thioureas are in the range
found for previously studied N-2-pyridyl-N 0-
arylthioureas [2–8]. The present thioureas can be
separated into two groups of three in terms of the non-
bonding N3· · ·N1 distance; PyTu3OMe, 3Pic-
˚
Tu3OMe and 5PicTu3OMe average ca. 2.67 A
while 4PicTu3OMe, 6PicTu3OMe and 4,6Lut-
thioureas [2–8]. Except for PyTu3OMe, the N3H3–
N1 angles for the present thioureas are between 135 and
1508 in agreement with the those found for previously
studied N-2-pyridyl-N0-arylthioureas [2–8].
The intermolecular N2H2· · ·S1 interaction, Fig.
1(d), is present in thioureas with intramolecular
hydrogen bonding to an oxygen [13–20] or nitrogen
atom [2–8], as well as thioureas without intramole-
cular hydrogen bonding [21–25]. The N2· · ·S1 non-
bonding distances show small differences for the
present thioureas, and generally, those thioureas with
the stronger intramolecular hydrogen bonding have
longer N2· · ·S1 distances. For example, in 6Pic-
˚
Tu3OMe average ca. 2.61 A. A similar grouping
occurs for the H3· · ·N1 distances, and therefore, the
methyl groups in the 4- and 6-positions (i.e. ortho and
para to the pyridine nitrogen) strengthen this
interaction by donation of electron density. This also
indicates that the methyl group in the 6-position of the
pyridine ring does not exert a significant steric effect.
Both distances for the two groups fall in the range
found for other substituted N-2-pyridyl-N0-aryl-
˚
Tu3OMe, N3· · ·N1 is 2.608(4) A and N2· · ·S1 is
˚
3.431(3) A, and in 5PicTu3OMe N3· · ·N1 is
˚
2.687(2) A and N2· · ·S1 is 3.386(2) A. The H2· · ·S1
˚

J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
227
Table 2
Crystallographic data and methods of data collection, solution and refinement for 5PicTu3OMe, 6PicTu3OMe and 4,6LuTu3OMe
Crystal data
5PicTu3OMe
C14H15ON3S
6PicTu3OMe
C14H15ON3S
Colorless, prism
0.24 £ 0.19 £ 0.10
293(2)
4,6LutTu3OMe
C15H17ON3S
Empirical formula
Crystal color, habit
Crystal size (mm)
Temperature (K)
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
Colorless, plate
1.03 £ 0.96 £ 0.12
293(2)
Colorless, prism
0.29 £ 0.24 £ 0.14
293(2)
Monoclinic
P21/c (#14)
10.9200(4)
15.3920(15)
8.1150(11)
90(0)
Triclinic
Orthorhombic
Pbca (#61)
16.3710(5)
7.4910(6)
24.1890(15)
90(0)
P-1 (#2)
7.4220(16)
9.944(3)
10.038(3)
104.815(9)
94.452(16)
108.134(14)
670.6(3)
a (8)
b (8)
g (8)
92.020(5)
90(0)
90(0)
90(0)
3
˚
Volume (A )
1363.1(2)
4
2966.4(3)
8
Z
2
Formula weight
273.35
273.35
287.37
Density (calcd) (g/cm3)
Absorption coefficient (mm21
Reflections for indexing
u range for data collection (8)
F(000)
1.332
1.354
1.291
)
0.233
0.237
0.218
191
270
210
3.35–26.36
576
3.53–26.31
288
3.00–26.37
1224
Index ranges
213 # h # 13
219 # k # 17
28 # l # 8
7305
28 # h # 8
212 # k # 11
211 # l # 12
3790
220 # h # 20
29 # k # 9
230 # l # 30
5327
Reflections collected
Independent reflections, Rint
Completeness to u (%)
Absorption correction
Max. and min. transmissions
Goodness-of-fit
6468, 0.0418
89.5
2423, 0.0894
89.0
2990, 0.0670
86.6
HKL-SCALEPACK
0.9726 and 0.7954
0.932
HKL-SCALEPACK
0.9767 and 0.9454
0.838
HKL-SCALEPACK
0.9702 and 0.9396
0.826
Data/restaints/parameters
˚
Largest diff. peak, hole, e (A
2596/0/210
0.130, 20.232
0.015(5)
2423/0/211
0.205, 20.220
0.055(11)
0.0535, 0.1539
0.0990, 0.1226
2990/0/216
0.196, 20.177
None
23
)
Extincton coefficient
R, wR2
0.0410, 0.0920
0.0895, 0.1056
0.0466, 0.1100
0.1346, 0.1359
R, wR2 (all reflections)
distance in one of the two molecules of 3PicTu3OMe
˚
is ca. 3.28 A, and this distance is longer in the second
1(d). The C3H· · ·S1 interactions when compared to
N2H· · ·S1 are the following: C3· · ·S1 is longer by
˚
˚
molecule making both considerably longer than the
other molecules of this study (and outside the arbitrary
˚
3.0 A we required for listing in Table 4). Therefore,
0.14–0.30 A, H· · ·S1 is longer by 0.19–0.44 A, and
the angle C3–H· · ·S1 is smaller by 14–348. These
ranges are comparable to previously studied to N-2-
pyridyl-N0-arylthioureas [6–8,26,27]. Other weak C–
H· · ·X interactions are listed in Table 3; only the
bulkiest member of the series, 4,6LutTu3OMe, did
not have a significant interaction by its methoxy
oxygen.
the steric effect of the methyl group in the 3-position
hinders the N2–H2· · ·S1 interaction that is common
to most thioureas. There are CH· · ·X interactions (i.e.
˚
H· · ·S distances ,3.00 A) listed in Table 3 for
3PicTu3OMe that partially make up for the absence
of a strong N2H2· · ·S1 interaction. Like other N-2-
pyridyl-N0-arylthioureas [6–8,26,27], other than
3PicTu3OMe, the rest of these thioureas have a
weak interaction, C3H3· · ·S1; S1 is positioned almost
equally between C3 and N2 of another molecule, Fig.
The data for the mean planes are shown in Table 5,
and there is substantial difference in the planarity of
these thioureas. The angle between the mean planes of
the pyridyl and aryl rings, as a measure of planarity, is
a useful parameter. The choice of this angle is most

228
J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
Fig. 2. ORTEP drawing showing PyTu3OMe with atom numbering scheme and displacement ellipsoids at 50% probability level.
useful since the angle between the mean planes of
the pyridine ring and the thiourea moiety does not
show large variation, 2–118, like other N-2-
pyridyl-N0-arylthioureas studied to date [2–8,26,
27]. In PyTu3OMe the angle between the pyridine
and aryl planes is essentially 908, and it is less
than 58 for 6PicTu3OMe and 4,6LutTu3OMe.
Therefore, the position and presence of methyl
groups on the pyridine ring affects the packing of
these molecules resulting in large differences in
their planarity.
3.2. Thermal studies
The DSC plots of these thioureas show a sharp
peak due to melting, and values for DHfus are shown in
Table 6 along with their melting points. The low value
for 3PicTu3OMe is due to the 3-methyl group
substantially reducing the strength of the N–H· · ·S
interaction. Similarly, the DHfus for N-2-(3-pico-
lyl)-N0-phenylthiourea is 21.3 kJ/mol [7], N-2-(3-
picolyl)-N0-4-tolylthiourea is 22.5 kJ/mol [26], and
that of N-2-(3-picolyl)-N0-4-chlorophenylthiourea
Fig. 3. ORTEP drawing of the four unique molecules of 3PicTu3OMe with atom numbering scheme and displacement ellipsoids at 50%
probability level.

J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
229
Fig. 4. ORTEP diagram showing 4PicTu3OMe with atom numbering scheme and displacement ellipsoids at 50% probability level.
intermolecular N2–H· · ·S1 interaction and also, the
weak C3–H·· ·S1 interaction is absent.
Even though there are weak intermolecular inter-
actions with the methoxy oxygen, it is significant that
these 3-methoxythioureas generally have lower DHfus
values than thioureas with methyl substituents on
either or both rings. This indicates that the weak
hydrogen bonding interactions are not as important as
the N2H· · ·S1 intermolecular interaction, and possibly
the accompanying C3H· · ·S1 interaction in thioureas
prepared from substituted 2-aminopyridines. The
melting points listed in the Table 6 are consistent
with these same conclusions.
Fig. 5. ORTEP diagram showing 5PicTu3OMe with atom
numbering scheme and displacement ellipsoids at 50% probability
level.
is 16.1 kJ/mol[28]. These values are substantially lower
than analogues with methyl groups on other positions of
the pyridine ring, as well as without a methyl group on
the ring. These data confirm that blocking the 3-position
of the pyridine ring reduces the strength of the
3.3. NMR spectral studies
The 1H NMR signals, Table 6, show little change in
chemical shift for the thioureas of this study except for
N3H (N0H), which is in a downfield position consistent
Fig. 6. ORTEP diagram showing 6PicTu3OMe with atom numbering scheme and displacement ellipsoids at 50% probability level.

230
J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
Fig. 7. ORTEP diagram showing 4,6LutTu3OMe with atom numbering scheme and displacement ellipsoids at 50% probability level.
Table 3
Selected bond distances (A) and angles (8) for PyTu3OMe, 3PicTu3OMe, 4PicTu3OMe, 5PicTu3OMe, 6PicTu3OMe and 4,6LuTu3OMe
˚
PyTu3OMe
3PicTu3OMea
4PicTu3OMe
5PicTu3OMe
6PicTu3OMe
4,6LuTu3OMe
˚
Distances (A)
S1–C7
N1–C2
N1–C6
N2–C2
N2–C7
N3–C7
N3–C8
C10–O1
O1–C15
1.690(4)
1.321(5)
1.350(5)
1.393(5)
1.368(5)
1.305(5)
1.437(5)
1.372(5)
1.420(7)a
1.664(3)
1.334(4)
1.335(5)
1.399(4)
1.376(4)
1.336(4)
1.410(4)
1.370(4)
1.406(4)
1.669(3)
1.331(4)
1.347(5)
1.395(4)
1.372(4)
1.336(4)
1.406(4)
1.370(4)
1.417(4)
1.6761(17)
1.329(2)
1.339(2)
1.401(2)
1.378(2)
1.336(2)
1.407(2)
1.377(2)
1.428(2)
1.6793(19)
1.328(2)
1.347(2)
1.393(2)
1.359(2)
1.331(2)
1.434(2)
1.367(3)
1.412(3)
1.679(3)
1.334(4)
1.352(4)
1.398(4)
1.377(4)
1.338(4)
1.413(4)
1.378(4)
1.422(4)
1.671(2)
1.333(3)
1.345(3)
1.403(3)
1.377(3)
1.338(3)
1.410(3)
1.373(3)
1.422(3)b
Angles (8)
C2–N2–C7
C7–N3–C8
N1–C2–N2
N2–C2–C3
S1–C7–N2
S1–C7–N3
N2–C7–N3
N3–C8–C9
N3–C8–C13
C9–C10–O1
C11–C10–O1
C10–O1–C15
129.8(4)
124.4(4)
118.6(4)
118.8(4)
118.1(3)
123.6(3)
118.3(4)
118.7(5)
119.4(5)
122.8(5)
115.6(4)
119.1(4)a
131.9(3)
131.1(3)
117.9(3)
118.6(3)
118.0(3)
127.3(3)
114.7(3)
115.5(3)
124.5(3)
124.3(3)
115.2(3)
117.7(3)
132.4(3)
130.72(16)
133.10(15)
118.47(15)
118.80(17)
117.85(13)
127.48(13)
114.67(14)
114.52(15)
125.74(16)
114.53(16)
124.05(17)
117.61(16)
131.22(18)
125.17.(16)
119.17(17)
118.51(17)
118.65(15)
124.03(15)
117.32(17)
118.21(18)
120.5(2)
130.5(3)
133.3(3)
117.9(3)
119.4(3)
118.1(2)
126.7(3)
115.2(3)
114.2(3)
125.7(3)
125.0(3)
114.3(3)
117.4(3)
130.8(2)
132.9(2)
118.5(2)
118.7(2)
118.0(2)
127.6(2)
114.4(2)
114.1(2)
126.2(2)
124.5(2)
115.0(3)
117.8(2)c
131.9(3)
118.2(3)
117.7(3)
117.2(3)
127.6(3)
115.2(3)
115.5(3)
125.3(3)
124.8(3)
115.0(3)
117.5(3)
123.8(2)
116.43(19)
117.01(17)
a
The second column represents the analogous bonds in the S2 molecule.
b
c
O1–C16.
C10–O1–C16.

J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
231
Table 4
˚
Intramolecular and intermolecular hydrogen bond distances (A) and angles (8) for PyTu3OMe, 3PicTu3OMe, 4PicTu3OMe, 5PicTu3OMe,
˚
6PicTu3OMe, and 4,6LutTu3OMe, as well as C–H· · ·X interactions with H· · ·X distances of less than 3.00 A
Thiourea
D
A
D–H
H· · ·A
D–H· · ·A
/(D–H· · ·A)
Intramolecular
PyTu3OMe
3PicTu3OMe
N3
N3
N6
N3
N3
N3
N3
N1
N1
N4
N1
N1
N1
N1
0.87(4)
0.83(3)
0.83(3)
0.88(2)
0.877(17)
0.86(3)
0.88(3)
2.00(5)
1.93(3)
1.96(4)
1.832(19)
1.96(2)
1.82(3)
1.83(3)
2.657(4)
2.658(4)
2.672(4)
2.6178(19)
2.687(2)
2.608(4)
2.614(3)
132(4)
145(3)
143(3)
147(2)
139.2(17)
150(3)
147(3)
4PicTu3OMe
5PicTu3OMe
6PicTu3OMe
4,6Lut3OMe
Intermolecular
PyTu3OMea
N2
C3
C6
C6
S1#1
S1#1
O1#2
O1#3
O1#3
O1#1
O1#1
O2#1
S1#3
S1#1
S1#1
O1#3
O1#2
S1#1
S1#1
O1#2
N3#3
S1#3
O1#4
S1#1
S1#1
O1#2
O1#3
N3#4
S1#1
S1#1
0.74(3)
0.93(4)
1.02(4)
1.02(4)
0.87(4)
0.96
0.96
0.96
0.96
0.86(2)
0.85(3)
0.900(19)
0.96
0.80(2)
0.92(2)
0.96(2)
0.98(2)
0.96
2.73(3)
2.92(4)
2.86(5)
2.75(5)
2.79(4)
2.50
2.91
2.51
2.93
2.72(2)
2.99(2)
2.82(2)
2.89
2.60(2)
2.81(2)
2.73(2)
2.94(2)
2.91
3.410(4)
3.666(5)
3.622(6)
3.447(6)
3.512(5)
3.426(5)
3.611(5)
3.383(5)
3.870(5)
3.5025(16)
3.641(2)
3.493(2)
3.711(3)
3.386(2)
3.619(2)
3.600(3)
3.819(3)
3.706(2)
3.679(3)
3.431(3)
3.732(4)
3.746(5)
3.569(5)
3.531(5)
3.505(3)
3.759(3)
153(3)
139(3)
132(4)
126(3)
142(4)
163.1
130.7
150.5
167.3
151.9(18)
135(2)
132.2(15)
144.6
169.5(18)
147.8(16)
150.8(16)
148.8(16)
140.7
N3
3PicTu3OMeb
4PicTu3OMec
5PicTu3OMed
C34
C15
C14
C14
N2
C3
C11
C15
N2
C3
C4
C6
C15
C15
N2
C3
C4
C11
C14
N2
0.96
2.84
146.1
6PicTu3OMee
0.93(4)
0.94(3)
0.93(4)
0.90(4)
0.96
2.51(4)
2.96(3)
2.89(4)
2.91(4)
2.87
174(3)
140(3)
154(3)
131(3)
126.8
4,6Lut3OMef
0.84(3)
0.96(3)
2.68(3)
2.89(2)
166(2)
151.3(19)
C3
a
#1: 1 2 x, 21 2 y, 2z; #2: 1 þ x, 21 þ y, z; #3: 1 2 x, 2y, 1 2 z.
#1: 2x, 21 2 y, 2z; #2: 1 2 x, 21 2 y, 1 2 z; #3: 2x, 2y, 1 2 z.
#1: 0.5 2 x, 20.5 2 y, 1 2 z; #2: 0.5 2 x, 0.5 þ y, 1.5 2 z.
b
c
d
e
f
#1: 2 2 x, 2y, 2z; #2: 21 þ x, 0.5 2 y, 0.5 þ z; #3: x, 0.5 2 y, 0.5 þ z; #4: 3 2 x, 1 2 y, 2z.
#1: 1 2 x, 21 2 y, 1 2 z; #2: x, 21 þ y, 21 þ z; #3: 2 2 x, 1 2 y, 2 2 z; #4: 2 2 x, 2y, 1 2 z.
#1: 2 2 x, 2y, 1 2 z.
with its involvement in intramolecular hydrogen
bonding in solution. The presence of a methyl group
in the 6-position on the pyridine ring (i.e. 6PicTu3OMe
and 4,6LutTu3OMe) provides sufficient additional
electron density to shift the N3H resonance further
downfield compared to other thioureas of this study,
Table 6. This same effect was found when comparing
the various N-2-picolyl-N0-phenylthioureas and for N-
2-(4,6-lutidyl)-N0-phenylthiourea [7]. Also, N2H is
somewhat upfield for thioureas with a 6-methyl group
in this series, as well as in the previous series [7].
4. Conclusions
The hydrogen bonding interactions are similar to
those of related N-2-pyridyl-N0-arylthioureas. The

Table 5
Mean plane data and angles between planes for PyTu3OMe, 3PicTu3OMe, 4PicTu3OMe, 5PicTu3OMe, 6PicTu3OMe and 4,6LutTu3OMe
Compound
PyTu3OMe
Plane
Plane
Mean plane deviation
Atom with greatest deviation
Plane/Plane
Angle
N1–C2–C3–C4–C5–C6
N2–C7–S1–N3
1
2
3
1
2
3
4
5
6
1
2
3
1
2
3
1
2
3
1
2
3
0.0056
0.0000
0.0073
0.0077
0.0059
0.0029
0.0078
0.0026
0.0066
0.0061
0.0008
0.0022
0.0029
0.0030
0.0045
0.0050
0.0037
0.0058
0.0026
0.0016
0.0053
C2, 0.0092(0.0035)
C7, 0.0001(0.0038)
C9, 0.0098(0.0028)
C3, 0.0118(0.0025)
C7, 0.0102(0.0029)
C12, 0.0050(0.0025)
C23, 0.0124(0.0024)
C27, 0.0046(0.0029)
C31, 0.0097(0.0025)
N1, 0.0096(0.0012)
C7, 0.0014(0.0013)
C8, 0.0033(0.0012)
C6, 0.0040(0.0015)
C7, 0.0051(0.0017)
C8, 0.0074(0.0013)
C2, 0.0081(0.0021)
C7, 0.0064(0.0025)
C12, 0.0085(0.00
2/1
3/2
1/3
2/1
3/2
1/3
5/4
6/5
4/6
2/1
3/2
1/3
2/1
3/2
1/3
2/1
3/2
1/3
2/1
3/2
1/3
2.66(0.35)
88.17(0.12)
89.68(0.13)
10.11(0.08)
29.64(0.07)
32.40(0.08)
3.25(0.09)
18.40(0.10)
15.72(0.10)
4.48(0.11)
10.93(0.11)
6.67(0.12)
2.86(0.12)
59.82(0.07)
57.95(0.07)
2.38(0.12)
5.57(0.11)
4.32(0.11)
3.76(0.11)
8.44(0.11)
4.92(0.10)
C8–C9–C10–C11–C12–C13
N1–C2–C3–C4–C5–C6
N2–C7–S1–N3
3PicTu3OMe
C8–C9–C10–C11–C12–C13
N4–C22–C23–C24–C25–C26
N5–C27–S2–N6
C28–C29–C30–C31–C32–C33
N1–C2–C3–C4–C5–C6
N2–C7–S1–N3
4PicTu3OMe
5PicTu3OMe
6PicTu3OMe
4,6LutTu3OMe
C8–C9–C10–C11–C12–C13
N1–C2–C3–C4–C5–C6
N2–C7–S1–N3
C8–C9–C10–C11–C12–C13
N1–C2–C3–C4–C5–C6
N2–C7–S1–N3
C8–C9–C10–C11–C12–C13
N1–C2–C3–C4–C5–C6
N2–C7–S1–N3
N1, 0.0042(0.0016)
C7, 0.0028(0.0020)
C13, 0.0085(0.0022)
C8–C9–C10–C11–C12–C13

J.M. Giesen et al. / Journal of Molecular Structure 613 (2002) 223–233
233
C.A. Presto, A.K. Hermetet, K.D. Haslow, L.J. Ackerman,
L.F. Szczepura, K.I. Goldberg, J.M. Giesen, W. Kaminsky,
D.X. West, J. Mol. Struct. 608 (2002) 77.
difference in the planarity among these thioureas is an
important aspect of their solid state properties and
results from the number and position of methyl
substituents causing different packing effects. The
very low values for DHfus and melting point for
3PicTu3OMe result from the steric effect of the 3-
methyl group weakening the intermolecular N2–
H· · ·S1 interaction. This is consistent with results
found for other N-2-(3-substituted) pyridyl N0-
arylthioureas [7,26,28].
[8] D.X. West, J.K. Swearingen, A.K. Hermetet, L.J. Ackerman,
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¨
Crystal Structures, University of Gottingen, Germany, 1997.
[12] L. Zsolnai, G. Huttner, ZORTEP, University of Heidelberg,
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5. Supplementary material
[13] A. Dago, M.A. Simonov, E.A. Pobedimskaya, A. Macias, A.
´
Martın, Kristallografiya 32 (1987) 1024.
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Center as supplementary publication no CCDC-
168211 for PyTu3OMe, CCDC-168212 for 3Pic-
Tu3OMe, CCDC-168213 for 4PicTu3OMe, CCDC-
168214 for 5PicTu3OMe, CCDC-168215 for 6Pic-
Tu3OMe and CCDC-168216 for 4,6LutTu3OMe.
Copies of available material can be obtained, free of
charge, on application to the Director, CCDC, 12
Union Road, Cambridge CB21EZ, UK, (fax: þ44-
1223-336033, e-mail: deposit@ccdc.cam.ac.uk).
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Acknowledgement is made to the Camille and
Henry Dreyfus Foundation for the partial support of
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