Spectral and structural studies of N-(2)-pyridylethyl-N'-arylthioureas

Article abstract of DOI:10.1016/S0022-2860(99)00332-4

N-(2-pyridylethyl)-N'-phenylthiourea, triclinic, P-1, a = 8.616(1) ?, b = 9.663(1) ?, c = 9.761(1) ?, α = 102.05(1)°, β = 102.36(1)°, and y = 116.17(1)°, V = 668.5(1) ?³, Z = 2, μ = 2.022 mm^-1, N-(2-pyridylethyl)- N'-p-tolylthiourea, triclinic, P-1, a = 8.804(3) ?, b = 9.951(2) ?, c = 10.255(2) ?, α = 115.03(2)°, β = 105.93(2)°, y = 104.04(2)°, V = 713.43(1) ?³, Z = 2, μ = 2.173 mm^-1, N-(2-pyridyl-ethyl)-N'-p- bromophenylthiourea, triclinic, P-1, a = 9.536(1) ?, b = 9.809(1) ?, c = 10.042(2) ?, α = 115.88(1)°, β = 96.80(1)°, and y = 110.44(1)°, V = 750.0(6) ?³, Z = 2, μ = 28.73 mm^-1, N-(2-pyridylethyl)-N'-p- nitrophenylthiourea, triclinic, P-1, a = 8.046(2) ?, b = 8.602(3) ?, c = 10.938(3) ?, α = 80.74(3)°, β = 89.77(2)°, y = 77.00(3)°, V = 727.6(6) ?³, Z = 2, μ = 2.325 mm^-1 and N-(2-pyridylethyl)-N'-p- methoxyphenylthiourea, monoclinic, P2₁/n, a = 11.526(2) ?, b = 9.723(2) ?, c = 13.460(2) ?, β = 100.49(2)°, V = 1483.3(2) ?3, Z = 4, μ = 1.929 mm^{- 1}. All five molecules possess an intramolecular hydrogen bond between NH and the pyridyl nitrogen, as well as intermolecular hydrogen bonding between N'H and a thione sulfur of a second molecule to form centrosymmetric dimers. Solution ¹H NMR studies (CDCl₃) show the N'H resonance downfield for each thiourea and its shift, as well as that of NH, is affected by substituents on the phenyl ring. (C) 2000 Elsevier Science B.V.

Full text of DOI:10.1016/S0022-2860(99)00332-4

Journal of Molecular Structure 524 (2000) 51–59
www.elsevier.nl/locate/molstruc
Spectral and structural studies of
N-(2)-pyridylethyl-N0-arylthioureas
a
a
b
b
´
´
´
J. Valdes-Martınez , S. Hernandez-Ortega , L.J. Ackerman , D.T. Li ,
J.K. Swearingenb, D.X. Westb,
*
a
´
´
´
´
Instituto de Quımica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan 04510,
´
Mexico D.F., Mexico
bDepartment of Chemistry, Illinois State University, Normal, IL 61790-4160, USA
Received 22 March 1999; accepted 15 July 1999
Abstract
0
ꢀ
ꢀ
ꢀ
N-(2-pyridylethyl)-N -phenylthiourea, triclinic, P-1, a ˆ 8:616ꢀ1† A; b ˆ 9:663ꢀ1† A; c ˆ 9:761ꢀ1† A; a ˆ 102:05ꢀ1†Њ; b ˆ
102:36ꢀ1†Њ; and g ˆ 116:17ꢀ1†Њ; V ˆ 668:5ꢀ1† A ; Z ˆ 2; m ˆ 2:022 mmϪ1; N-(2-pyridylethyl)-N0-p-tolylthiourea, triclinic, P-
ꢀ 3
ꢀ
ꢀ
ꢀ
ꢀ 3
1, a ˆ 8:804ꢀ3† A; b ˆ 9:951ꢀ2† A; c ˆ 10:255ꢀ2† A; a ˆ 115:03ꢀ2†Њ; b ˆ 105:93ꢀ2†Њ; g ˆ 104:04ꢀ2†Њ; V ˆ 713:43ꢀ1† A ;
Z ˆ 2; m ˆ 2:173 mmϪ1; N-(2-pyridyl-ethyl)-N -p-bromophenylthiourea, triclinic, P-1, a ˆ 9:536ꢀ1† A; b ˆ 9:809ꢀ1† A; c ˆ
0
ꢀ
ꢀ
10:042ꢀ2† A; a ˆ 115:88ꢀ1†Њ; b ˆ 96:80ꢀ1†Њ; and g ˆ 110:44ꢀ1†Њ; V ˆ 750:0ꢀ6† A ; Z ˆ 2; m ˆ 28:73 mmϪ1; N-(2-pyridyl-
ꢀ
ꢀ 3
0
ꢀ
ꢀ
ꢀ
ethyl)-N -p-nitrophenylthiourea, triclinic, P-1, a ˆ 8:046ꢀ2† A; b ˆ 8:602ꢀ3† A; c ˆ 10:938ꢀ3† A; a ˆ 80:74ꢀ3†Њ; b ˆ
89:77ꢀ2†Њ; g ˆ 77:00ꢀ3†Њ; V ˆ 727:6ꢀ6† A ; Z ˆ 2; m ˆ 2:325 mm and N-(2-pyridylethyl)-N0-p-methoxyphenylthiourea,
Ϫ1
ꢀ 3
ꢀ
ꢀ
ꢀ
ꢀ 3
monoclinic, P21/n, a ˆ 11:526ꢀ2† A; b ˆ 9:723ꢀ2† A; c ˆ 13:460ꢀ2† A; b ˆ 100:49ꢀ2†Њ; V ˆ 1483:3ꢀ2† A ; Z ˆ 4; m ˆ
1:929 mmϪ1: All five molecules possess an intramolecular hydrogen bond between NH and the pyridyl nitrogen, as well as
intermolecular hydrogen bonding between N0H and a thione sulfur of a second molecule to form centrosymmetric dimers.
Solution H NMR studies (CDCl3) show the N0H resonance downfield for each thiourea and its shift, as well as that of NH, is
1
affected by substituents on the phenyl ring. ᭧ 2000 Elsevier Science B.V. All rights reserved.
Keywords: Thioureas; Hydrogen bonding; Crystal structure; N-pyridylethylthioureas
1. Introduction
aryl rings) have been characterized structurally and
spectroscopically [3,4]. Intermolecular NH hydrogen
bonding with a sulfur of a neighboring molecule to
form centrosymmetric dimers is also present in these
thioureas. Here we report structural and spectroscopic
studies of five N-(2-pyridylethyl)-N0-arylthioureas in
which the NH, rather than the N0H in the previously
studied thioureas [2–4], is capable of intramolecular
hydrogen bonding to the pyridyl nitrogen. N0H is
expected to be involved in intermolecular hydrogen
bonding to a sulfur of a neighboring molecule. The
five thioureas studied here and their symbols are
Although 1H NMR has correctly predicted intramo-
lecular hydrogen bonding involving the pyridyl
nitrogen and N0H for N-(2-pyridyl)-N0-phenylthiourea
[1], only recently has a structural study been reported
[2]. Other examples of substituted N-(2-pyridyl)-N0-
arylthioureas (i.e. substituents on the pyridyl and/or
* Corresponding author. Tel.: ϩ 1-309-438-7661; fax: ϩ 1-309-
438-5538.
E-mail address: dxwest@ilstu.edu (D.X. West).
0022-2860/00/$ - see front matter ᭧ 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-2860(99)00332-4

´
´
52
J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
Fig. 1. Preparation reaction for the 5-thiourea prepared from 2-amionethylpyridine.
the following: N-(2-pyridylethyl)-N0-phenylthiourea,
PyEtTuPh; N-(2-pyridylethyl)-N0-p-tolylthiourea,
PyEtTupT; N-(2-pyridylethyl)-N0-p-bromophenyl-
thiourea, PyEtTupBrPh; N-(2-pyridylethyl)-N0-p-
nitrophenylthiourea, PyEtTupNO2Ph and N-(2-pyri-
dylethyl)-N0-p-methoxyphenylthiourea, PyEtTupO-
MePh.
mounted in random orientation on a glass fiber on a
Siemens P4 Four Circle Diffractometer or a Nonius
Mach 3 diffractometer. The structures were solved
with direct methods and missing atoms were found
by difference-Fourier synthesis. All non-hydrogen
atoms were refined with anisotropic temperature factors
and all hydrogens were found on the difference-Fourier
map. The H atoms of CH were allowed to ride on the C
atoms and assigned a fixed isotropic temperature factor,
ꢀ 2
U ˆ 0:05 A . Only the coordinates of the H atoms
2. Experimental
attached to N and N’ were refined. Scattering factors
for PyEtTuPh and PyEtTupOMePh were taken from
International Tables for X-ray Crystallography
(1974, Vol. IV), and all calculations were done with
the shelxtl pc௣ program package [5]. Scattering
factors for PyEtTupT, PyEtTupBrPh and PyEtTup-
NO2Ph are from Wassmaire and Kirfel [6], and calcu-
lations were done by maXus, version 2.0 [7].
The various isothiocyanates and 2-aminoethylpyr-
idine were purchased from Aldrich and used as
received. The desired aryl isothiocyanate was mixed
in a 1:1 molar ratio with 2-aminoethylpyridine in
anhydrous EtOH, and the resulting mixture gently
refluxed for a minimum of 1 h. On cooling and slowly
evaporating the reactant mixture (35ЊC), the thioureas
crystallized from solution (see Fig. 1). The solids were
filtered, washed with cold isopropanol followed by
anhydrous ether, dried on a warm plate and then
stored until required for characterization. Their
melting points are as follows: PyEtTuPh, 112–
114ЊC; PyEtTupT, 109–111ЊC; PyEtTupBrPh, 128–
130ЊC; PyEtTupNO2Ph, 159–160ЊC; and PyEtTupO-
MePh, 119–120ЊC. Their 1H NMR spectra were
recorded in CDCl3 with a Varian Gemini 2000
300 MHz spectrometer. IR spectra were recorded as
Nujol mulls between NaCl plates with a Nicolet 5SCX
FT Spectrometer and UV spectra with a Cary 5E spec-
trophotometer in 1 cm cells.
The crystallographic data and methods of data
collection, solution and refinement are shown in
Tables 1 and 2; the atomic coordinates and equivalent
isotropic displacement coefficients are included in
the deposited material (CCDC), as are a complete
list of bond distances and angles. The CCDC#s are
as follows: PyEtTuPh ˆ 113 878; PyEtTupT ˆ
113 877; PyEtTupBrPh ˆ 113 879; PyEtTupNO2Ph
ˆ 113 881 and PyEtTupOMePh ˆ 113 880:
3. Results and discussion
Crystals of the thioureas were grown by slow
evaporation of anhydrous ethanolic solutions
(filtrates) at room temperature. The crystals were
3.1. Structural studies
PyEtTupBrPh, PyEtTupNO2Ph and PyEtTupOMePh

´
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J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
53
Table 1
Crystallographic data and methods of data collection, solution and refinement for PyEtTuPh and PyEtTupT
Crystal data
PyEtTuPh
PyEtTupT
Empirical formula
Crystal color, habit
Crystal size (mm)
Crystal system
C14H15N3S
Colorless prism
0.40 × 0.24 × 0.12
Triclinic
P-1
8.616(1)
9.663(1)
9.761(1)
102.05(1)
102.36(1)
116.17(1)
668.5(1)
2
C15H17N3S
Yellow, prism
0.30 × 0.26 × 0.12
Triclinic
P-1
8.804(2)
9.951(2)
10.255(2)
115.03(2)
105.93(2)
104.04(2)
713.43(1)
2
Space group
˚
a (A)
˚
b (A)
˚
c (A)
a (Њ)
b ((Њ)
g (Њ)
Volume (A )
Z
3
˚
Formula weight
Density (calc.) (g/cm3)
Absorp. Coeff., mmϪ1
F(000)
257.35
1.279
2.022
272
271.4
1.30
2.173
288
Data collection
Diffractometer
Radiation l (A)
Siemens P4/PC
CuKa(1.54178 A)
Nonius Mach 3
MoKa(0.70930 A)
˚
˚
˚
Temperature (K)
Monochromator
Graphite crystal
Graphite crystal
2u range
293(2)
Highly oriented
Highly oriented
293(2)
3 to 110.0Њ
u/2u
2 to 55.0Њ
v/u
Scan type
Scan range (v)
Index ranges
0.70Њ
0.80Њ
Ϫ1 Յ h Յ 9
Ϫ9 Յ k Յ 9
Ϫ10 Յ l Յ 10
2053
1647 (5.62 %)
1382 {I Ͼ 2.0s(I)}
Semi-empirical
0 Յ h Յ 11
Ϫ12 Յ k Յ 12
Ϫ13 Յ l Յ 12
3589
3249 (1.70%)
2612 {I Ͼ 3.0s(I)}
c-scan
Reflections collected
Ind. Reflec.(Rint)
Observed reflections
Absorption correction
Solution and refinement
Solution method
Direct methods
1.085
Direct methods
2.464
2612/0/178
0.67
Goodness-of-fit on F2
Data /restraints/parameters
Largest diff. Peak (eA
Largest diff. hole (eA
1647/2a/170
0.294
Ϫ3
˚
˚
)
Ϫ3
)
Ϫ0.755
Ϫ0.31
Largest and mean D/s
R1, wR2
R1, wR2 (all data)
Programs used
0.000, 0.000
0.0693, 0.1935
0.0799, 0.2085
shelxtl plus
0.000, 0.000
0.0560, 0.0622 (vR)
0.0708, 0.0637 (vR)
MaXus
a
˚
The 2 N–H bond distances were restrained to 0.90(1) A.
are in a conformation resulting from intramolecular
hydrogen bonding of NH to the pyridine nitrogen, N1.
However, for PyEtTuPh and PyEtTupT, the NH
hydrogen is further from the pyridyl nitrogen than
an NH hydrogen from a neighboring molecule.
Perspective views of PyEtTupT, representing of N-
(2)-pyridylethyl-N0-arylthioureas without intramol-
ecular hydrogen bonding, and PyEtTupNO2Ph,

´ ´
J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
54
Table 2
Crystallographic data and methods of data collection, solution and refinement for PyEtTupBrPh, PyEtTupNO2Ph and PyEtTupMeOPh
Crystal data
PyEtTupBrPh
PyEtTupNO2Ph
PyEtTupOMePh
Empirical formula
Crystal color, habit
Crystal size (mm)
Crystal system
C14H14BrN3S
Colorless prism
0.32 × 0.24 × 0.10
Triclinic
P-1
9.536(1)
9.809(1)
10.042(2)
115.88(1)
96.80(1)
110.44(1)
750.0(6)
2
C14H14N4O2S
Yellow prism
0.34 × 0.24 × 0.10
triclinic
P-1
8.046(2)
8.602(3)
10.938(3)
80.74(3)
89.77(2)
77.00(3)
727.6(6)
2
C15H17N3OS
Colorless, prism
0.32 × 0.28 × 0.12
Monoclinic
P21/n
11.526(2)
9.723(2)
13.460(2)
90.00
100.49(2)
90.00
1483.3(2)
4
Space group
˚
a (A)
˚
b (A)
˚
c (A)
a (Њ)
b ((Њ)
g (Њ)
Volume (A )
Z
3
˚
Formula weight
Density (calcd.) (g/cm3)
Absorp. Coeff., mmϪ1
F(000)
336.3
1.30
28.734
356
302.4
1.30
2.325
316
287.4
1.287
1.929
608
Data collection
Diffractometer
Radiation l (A)
Nonius Mach 3
MoKa(0.70930 A)
Nonius Mach 3
MoKa(0.70930 A)
Siemens P4/PC
CuKa(1.54178 A)
˚
˚
˚
˚
Temperature (K)
Monochromator
2u range
293(2)
293(2)
293(2)
Highly oriented Graphite crystal
2.0 to 55.0Њ
v/u
Highly oriented graphite crystal
2.0 to 55.0Њ
v/u
Highly oriented Graphite crystal
3 to 110.0Њ
u/2u
Scan type
Scan range (v)
Index ranges
0.80
0.80Њ
0.80Њ
0 Յ h Յ 12
Ϫ 11 Յ k Յ 11
Ϫ 13 Յ l Յ 12
3779
3644 (1.0 %)
2346 {F Ͼ 3.0 s (I)}
c-scan
0 Յ h Յ 10
Ϫ 11 Յ k Յ 11
Ϫ 14 Յ l Յ 14
3722
3346 (3.3 %)
2408 {F Ͼ 3.0 s (I)}
c-scan
Ϫ 1 Յ h Յ 12
Ϫ 1 Յ k Յ 10
Ϫ 14 Յ l Յ 14
2497
1859 (4.90 %)
1655 {F Ͼ 3.0 s((F)}
Face-indexed numerical
Reflections collected
Ind. Reflec. (Rint)
Observed reflections
Absorption correction
Solution and refinement
Solution method
Direct methods
0.833
Direct methods
1.293
Direct methods
1.28
Goodness-of-fit on F2
Data/restraints/parameters
2346/0/172
0.294
Ϫ 0.755
2408/0/190
0.52
Ϫ 0.27
1859/0/221
0.19
Ϫ 0.18
Ϫ3
˚
Largest diff. peak (eA
)
Ϫ3
˚
Largest diff. hole (eA
)
Largest and mean D/s
R1, wR [I Ͼ 3s(I)]
R1, wR2 (all data)
Programs used
0.000, 0.000
0.0513, 0.0440
0.0918, 0.0499
MaXus
0.000, 0.000
0.0407, 0.0343
0.0648, 0.0379
MaXus
0.029, 0.005
0.0417, 0.0573 wR2
0.0459, 0.0602 wR2
shelxtl plus
representing those with intramolecular hydrogen
bonding are shown in Figs. 2 and 3. Representative
packing diagrams of PyEtTuPh and PyEtTupMeOPh
are shown in Figs. 4 and 5. Inspection of Table 3
shows that the bond distances and angles for the five
2-pyridyl thioureas are within three orders of magni-
tude of their estimated standard deviations, and the
largest differences occur close to the aryl substituent
as would be expected. However, the nature of the aryl
ring substituents does not have a large effect on the
bond distances and angles of the thiourea moiety.
The intramolecular and intermolecular hydrogen
bonding data are shown in Table 4. PyEtTupBrPh,
PyEtTupNO2Ph, and PyEtTupMeOPh show similar

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J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
55
Fig. 2. A perspective view of PyEtTupT showing intermolecular hydrogen bonding.
distances and angles for their intramolecular N2–
for the three. The thiourea moiety has an average
deviation from the mean plane of no greater than
0.003 A for any of these thioureas and C9 is the
…
…
H2 N1 hydrogen bonds. Intramolecular N2 N1
…
˚
distances and N2–H2 N1 angles for PyEtTuPh
˚
˚
{3.294(7) A, 124(3)Њ} and PyEtTupT {3.352(2) A,
110(11)Њ} are well outside the range normally asso-
atom that has the greatest deviation from the mean
plane, except in PyEtTupT where N2 shows the
greatest deviation. Since PyEtTuPh and PyEtTupT
do not intramolecularly hydrogen bond and PyEt-
TupBrPh, PyEtTupNO2Ph and PyEtTupMeOPh do,
there is a significant difference in the angles between
the pyridyl ring and thiourea moiety. This angle is
greater in the molecules with intermolecular N2–
…
˚
ciated with N–H N hydrogen bonding (2.6–3.1 A,
130–180Њ) [8]. Instead, these molecules have intermo-
…
lecular N2–H2 N1A hydrogen bonds. All five
…
thioureas are involved in intramolecular N3–H SA
hydrogen bonding and the non-bonding distance
between N3 and a SA on a neighboring molecule is
˚
…
in the normal range of 3.2–3.5 A [9]. Two molecules
H2 N1A hydrogen bonds (i.e. PyEtTuPh and PyEt-
arrange themselves, so that both N3H’s hydrogen
bond with the other sulfur, to form dimers with
eight-members. The N2–H SA angles for these
TupT), suggesting that the pyridyl ring is rotated to
point to N2H hydrogen of another molecule.
…
five thioureas are quite similar. Neither the nitro
group of PyEtTupNO2Ph nor the methoxy group of
PyEtTupMeOPh are involved in intermolecular
hydrogen bonding (i.e. classical hydrogen bonding).
Table 5 shows the angles between the mean planes
for the pyridyl ring, the thiourea moiety, and the
aromatic ring as well as the mean plane deviations
3.2. Spectral studies
The u.v. spectra (DMF) show two bands for four of
the N-(2-pyridylethyl)-N0-arylthioureas and a three
bands for PyEtTupNO2Ph. The higher energy band,
ca. 37,500 cmϪ1 we assign to a combination of p !
pء transitions from both the pyridinyl and aromatic

´
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J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
Fig. 3. A perspective view of PyEtTupNO2Ph.
Fig. 4. Packing diagram for PyEtTuPh.

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J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
57
presence of the nitro group shifts the other two
bands to higher energy compared to their positions
in the other four thioureas.
In the infrared spectra of the five thioureas we have
assigned n(N0H) to medium intensity absorptions in
the 3260–3325 cmϪ1 region. The thioamide IV band,
which owes considerable intensity to n(CS), is
assigned in the range 800–860 cmϪ1 agreement with
previously studied thioureas [3,4].
In contrast to their crystal structures, the chemical
shifts for N2H do not indicate intramolecular
hydrogen bonding in CDCl3 solution for PyEt-
TupBrPh, PyEtTupNO2Ph and PyEtTupMeOPh. The
…
fact that these five thioureas have N2–H2 SA angles
that are at the low end of the range (i.e. 120–130Њ) for
this type of hydrogen bond is probably related to its
1
disappearance on dissolution in CDCl3. The H NMR
spectra show some variation in the shift of the reso-
nance due to the aryl substituent with the resonances
for both NHs being affected (Table 6). The increased
negative inductive effect of the nitro group causes a
downfield shift while the methoxy function causes an
upfield shift; the d values vary in the order NO2 Ͼ
Br Ͼ H Ͼ Me Ͼ OMe for the resonance we have
assigned to N0H, which is our basis for the assign-
ment. All other chemical shifts shown in Table 6 are
affected to a lesser extent by the aryl substituents.
In conclusion, the lack of intramolecular hydrogen
Fig. 5. Packing diagram for PyEtTupOMePh.
rings. The band in the 34 500 cmϪ1 region of the
spectrum with a molar absorptivity of approximately
105 MϪ1 cmϪ1 is due to a combination of n ! pء
bands of the heterocyclic ring and thiourea moiety.
PyEtTupNO2Ph has a band at 28,120 cmϪ1 due to a
n ! pءtransition of the nitro group which also has a
molar absorptivity of about 105 MϪ1 cmϪ1. The
Table 3
˚
Selected bond distances (A) and angles (Њ) for PyEtTuPh, PyEtTupT, PyEtTupBrPh, PyEtTupNO2Ph and PyEtTupOMePh
PyEtTuPh
PyEtTupT
PyEtTupBrPh
PyEtTupNO2Ph
PyEtTupOMePh
˚
Bond distances (A)
S1–C9
N1–C2
N1–C6
N2–C8
N2–C9
N3–C9
N3–C10
1.688(4)
1.331(6)
1.332(7)
1.444(6)
1.326(6)
1.358(6)
1.418(6)
1.698(1)
1.336(2)
1.349(2)
1.449(2)
1.325(2)
1.372(2)
1.432(2)
1.686(6)
1.345(8)
1.349(8)
1.464(7)
1.336(6)
1.366(7)
1.421(7)
1.693(1)
1.340(2)
1.341(2)
1.463(1)
1.331(1)
1.366(1)
1.417(1)
1.691(2)
1.332(4)
1.345(4)
1.454(4)
1.324(4)
1.354(4)
1.432(3)
Bond angles (Њ)
C2–N1–C6
N1–C2–C7
C7–C8–N2
C8–N2–C9
N2–C9–S1
N2–C9–N3
N3–C9–S1
C9–N3–C10
117.1(4)
116.8(4)
111.1(4)
123.6(4)
122.6(3)
117.4(4)
120.1(4)
128.1(4)
116.3(2)
115.4(1)116.2(8)
108.8(1)
123.0(1)
123.6(1)
117.7(1)
118.6(1)
127.1(1)
117.1(5)
116.0(2)
111.8(8)
122.8(4)
122.8(4)
117.6(4)
119.6(4)
127.8(4)
118.0(1)
117.3(3)
111.3(3)
123.3(1)
123.2(1)
117.9(1)
118.8(1)
128.3(1)
117.6(3)
113.1(3)
126.1(2)
123.5(2)
117.2(2)
119.3(2)
127.6(2)

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J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
58
Table 4
˚
Intramolecular and intermolecular hydrogen bond distances (A) and angles (Њ)
Mode
PyEtTuPh
PyEtTupT
PyEtTupBrPh
PyEtTupNO2Ph
PyEtTupOMePh
Intramolecular
…
˚
H2 N1 (A)
2.26(1)
2.94(2)
128(5)
2.162(3)
2.900(4)
130(2)
2.38(3)
2.841(3)
115(3)
…
˚
N2–H2 N1 (A)
…
ЄN2–H2 N1 (Њ)
Intermolecular
…
˚
H2 N1A (A)
…
2.39(3)
3.040(7)a
130(3)
2.19(1)
2.996(1)b
156(13)
2.51(1)
˚
N2–H2 N1A (A)
ЄN2–H2 N1A (Њ)
…
˚
…
H3 SA (A)
…
2.51(2)
2.536(2)
3.375(6)b
162(5)
2.44(7)
3.423(2)e
165(2)
2.57(4)
3.394(3)d
165(3)
3.382(4)c
165(4)
3.460(1)d
161(11)
˚
N3–H3 SA (A)
…
ЄN3–H3 SA (Њ)
a Ϫx ϩ 1; Ϫy; Ϫz ϩ 2:
b Ϫx ϩ 1; Ϫy ϩ 1; Ϫz ϩ 1:
c Ϫx; Ϫy; Ϫz ϩ 1:
d Ϫx ϩ 2; Ϫy ϩ 2; Ϫz:
e Ϫx; Ϫy ϩ 1; Ϫz ϩ 1:
Table 5
Thiourea mean plane deviation and angles between planes (plane A ˆ mean plane of pyridine ring, plane B ˆ mean plane of the thiourea
moiety, N–C(S)– N0 and plane C ˆ mean plane of the six carbons of the aromatic ring)
Compound
A
B
C
ЄA/B
ЄB/C
ЄA/C
PyEtTuPh
PyEtTupT
PyEtTupBrPh
PyEtTupNO2Ph
PyEtTupOMePh
0.0082(3)
0.0041(2)
0.0065(6)
0.0038(3)
0.0066(3)
0.0023(2)
0.0010(3)
0.0001(1)
0.0027(2)
0.0020(3)
0.0028(2)
0.0049(2)
0.0056(4)
0.0065(3)
0.0052(3)
74(1)
80(4)
51(4)
36(4)
40(1)
49(1)
48(4)
55(3)
50(4)
55(1)
28(1)
40(4)
23(4)
21(4)
16(1)
Table 6
1H NMR (d), ultraviolet (cmϪ1) and infrared (cmϪ1) spectral data for PyEtTuPh, PyEtTupT, PyEtTupBrPh, PyEtTupNO2Ph and PyEtTupO-
MePh
Compound
C6H
N0H
NH
CH2N
CCH2
p ! pء
n ! pء
n(CyS)
n(N0H)
PyEtTuPh
PyEtTupT
PyEtTupBrPh
PyEtTupNO2Ph
8.145
8.172
8.212
8.295
8.067
7.730
8.212
8.886
7.939
7.660
7.899
8.572
4.020
4.026
4.078
4.144
3.029
3.042
3.096
3.170
37,630
37,580
37,880
39,560
34,760(4.92)a
34,830(4.95)
33,930(5.00)
35,300(5.02)
28,180(5.06)
34,590(4.97)
836m
836m
826m
858m
3296sh
3263m
3280m
3313m
PyEtTupOMePh
8.144
7.625
7.594
4.003
3.016
37,580
820m
3322m
a Values in parentheses are log 10e.

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´
J. Valdes-Martınez et al. / Journal of Molecular Structure 524 (2000) 51–59
59
bonding with the pyridyl nitrogen for PyTuEtPh and
Acknowledgements
PyTuEtpT, which have the smallest para substituents
on their aromatic rings (i.e. H and Me, respectively) is
somewhat surprising. As indicated earlier this results
in the pyridyl mean plane being at a much larger angle
(i.e. 74–80Њ) with the thiourea moiety mean plane
than found for the other three thioureas (i.e. 36–
51Њ). The behavior of these latter thioureas in not
due to an inductive effect of the aryl substituent
since both PyEtTupNO2Ph and PyEtTupMeOPh do
form intramolecular hydrogen bond, but may be a
steric effect since their aryl substituents are larger.
The intermolecular hydrogen bond involving the
pyridyl nitrogen in PyTuEtPh and PyTuEtpT results
Acknowlegment is made to the Donors of the Petro-
leum Research Fund, administered by the American
Chemical Society, the National Science Foundation
and the Consejo Nacional de Ciencia y Tecnologia
for the partial support of this research.
References
[1] A. Kascheres, M. Ueno, J. Heterocyclic Chem. 28 (1991) 2057.
´
´
[2] D.X. West, A.K. Hermetet, L.J. Ackerman, J. Valdes-Martınez,
´
S. Hernandez-Ortega, Acta Cryst. C55 (1999) 811.
[3] D.X. West, C.A. Presto, A.K. Hermetet, K.D. Haslow, L.J.
´
´
´
Ackerman, J. Valdes-Martınez, S. Hernandez-Ortega, G. Espi-
…
in a slightly longer N2–H1 N1A than found for the
´
nosa-Perez, J. Chem. Cryst. (1999) in press.
intramolecular hydrogen bonding. We are continuing
to study additional PyEtTu aromatic derivatives with
other para substituents, as well as meta and ortho
substituents.
Supplementary material: Crystallographic data
(excluding structure factors) for the structures
reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supple-
mentary publication No. CCDC-1003/m. Copies of
available material can be obtained, free of charge,
on application to the Director, CCDC, 12 Union
Road, teched@chemcrys.cam.ac.uk.
´
´
´
[4] J. Valdes-Martınez, S. Hernandez-Ortega, D.X. West, L.J.
Ackerman, J.K. Swearingen, A.K. Hermetet, J. Mol. Struct.
(1999) 478 (1999) 219.
[5] Siemens shelxtl pc௣: Release 4.1 for Siemens Crystallo-
graphic Research System, Siemens Analytical X-ray Instru-
ments, Inc., Madison, WI, USA, 1990.
[6] D. Wassmaier, A. Kirfel, Acta Cryst. A51 (1995) 416.
[7] S. Mackay, C. Edwards, A. Henderson, C. Gilmore, N. Stewart,
K. Shankland, A. Donald, University of Glasgow, Scotland,
1997.
[8] M.C. Etter, Acc. Chem. Res. 23 (1990) 120.
[9] A. Ramnathan, K. Sivakumar, K. Subramanian, N. Srinivasan,
K. Ramadas, H.-K. Fun, Acta Cryst. C52 (1996) 656 and refer-
ences therein.