Structural, spectral and thermal studies of N-2-(picolyl)-N′-4-chlorophenylthioureas

Article abstract of DOI:10.1016/S0022-2860(01)00966-8

N-2-(4-picolyl)-N′-4-chlorophenylthiourea, 4PicTu4ClPh, triclinic, P-1, a = 7.5235(3), b = 9.1585(5), c = 10.5158(7) ?, α = 76.015(3), β = 70.015(4), γ = 82.010(4)°, V = 1309.8(2) ?³ and Z = 2; N-2-(5-picolyl)-N′-4-chlorophenylthiourea, 5PicTu4

Full text of DOI:10.1016/S0022-2860(01)00966-8

Journal of Molecular Structure 608 ꢀ2002) 245±251
www.elsevier.com/locate/molstruc
Structural, spectral and thermal studies of
N-2-ꢀpicolyl)-N0-4-chlorophenylthioureas
Lisa F. Szczepuraa, Diantha R. Kelmanb, Anne K. Hermeteta, Lily J. Ackermana,
Karen I. Goldbergb, Kacey A. Clabornb, Werner Kaminskyb, Douglas X. Westb,
*
aDepartment of Chemistry, Illinois State University, Normal, IL 61790-4160, USA
bDepartment of Chemistry, 351700, University of Washington, Seattle, WA 98195-1700, USA
Received 1 August 2001; revised 30 November 2001; accepted 30 November 2001
Abstract
0
ꢀ
N-2-ꢀ4-picolyl)-N -4-chlorophenylthiourea, 4PicTu4ClPh, triclinic, P-1, a ˆ 7:5235ꢀ3†; b ˆ 9:1585ꢀ5†; c ˆ 10:5158ꢀ7† A;
a ˆ 76:015ꢀ3†; b ˆ 70:015ꢀ4†; g ˆ 82:010ꢀ4†8; V ˆ 1309:8ꢀ2† A and Z ˆ 2; N-2-ꢀ5-picolyl)-N0-4-chlorophenylthiourea,
ꢀ 3
ꢀ
ꢀ 3
5PicTu4ClPh, monoclinic, P21/c, a ˆ 15:139ꢀ2†; b ˆ 4:8386ꢀ3†; c ˆ 17:338ꢀ2† A; b ˆ 90:661ꢀ4†8; V ˆ 1270:0ꢀ2† A and Z ˆ
4 and N-2-ꢀ6-picolyl)-N0-4-chlorophenylthiourea, 6PicTu4ClPh, monoclinic, C2/c, a ˆ 33:520ꢀ6†; b ˆ 4:0750ꢀ3†; c ˆ
ꢀ
ꢀ 3
18:658ꢀ4† A; b ˆ 97:500ꢀ6†8; V ˆ 2526:8ꢀ7† A and Z ˆ 8: The most striking difference between the structures of the three
thioureas is the difference in planarity, and among the four N-2-ꢀpicolyl)-N0-4-chlorophenylthioureas, their values for DHfus.
q 2002 Elsevier Science B.V. All rights reserved.
Keywords: 2-Pyridylthioureas; Chlorophenylthioureas; Crystal structures; Hydrogen bonding; Enthalpy of fusion
1. Introduction
dimethoxyphenyethyl)thiourea [5] and four thioureas
with p-substituted aryl groups including N-ꢀ2-
pyridyl)-N0-ꢀ4-chlorophenyl)thiourea [6] have been
reported. A study of the structural, thermal and spec-
tral properties of the N-2-ꢀpicolyl)- and N-ꢀ4,6-
lutidyl)-N0-phenylthioureas has been communicated
[7]. A recent report showed that some members of a
series of N-ꢀ2-pyridyl)-N0-2-methoxyphenylthioureas
possess bifurcated intramolecular hydrogen bonding
involving the pyridyl nitrogen and methoxy oxygen
[8]. A similar study of the N-2-ꢀ4,6-lutidyl)-N0-chlor-
ophenylthioureas showed that N-2-ꢀ4,6-lutidyl)-N0-4-
chlorophenylthiourea has interaction between methyl
hydrogens and the chlorine atoms ꢀi.e. H´´´Cl
After a 1H NMR study of the intramolecular
hydrogen bonding between the pyridyl nitrogen and
N0H for N-ꢀ2-0pyridyl)thioureas [1], the structure of N-
ꢀ2-pyridyl)-N0-phenylthiourea was reported [2]. Intra-
molecular N ±H´´´N and intermolecular N±H´´´S
hydrogen bonding, as well as the planarity of the
molecules, has been the focus in recent structural
studies of substituted N-ꢀ02-pyridyl)-N0-arylthioureas
including N-ꢀ2-pyridyl)-N -tolylthioureas [3] and the
N-2-ꢀ4,6-lutidyl)-N0-tolylthioureas [4]. In addition,
the structures of N-ꢀ5-bromo-2-pyridyl)-N0-2-ꢀ2,5-
Ê
distances ,3.00 A), as well as the expected intramo-
lecular and intermolecular hydrogen bonding [9].
Since C±H´´´Cl interactions in N-2-ꢀpyridyl)-N0-4-
* Corresponding author. Tel.: 11-206-616-4213; fax: 11-206-
685-8665.
E-mail address: westdx@chem.washington.edu ꢀD.X. West).
0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-2860ꢀ01)00966-8

246
L.F. Szczepura et al. / Journal of Molecular Structure 608 :2002) 245±251
used as received. The desired 2-aminopicoline was
mixed in a 1:1 molar ratio with 4-chlorophenyl
isothiocyanate in 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 and were
®ltered and stored until required for spectral and
thermal characterization. The yields are ca. 70% for
each of the thioureas and their melting points are
listed in Table 5 with the enthalpies of fusion. 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 10 8C/min using a
Perkin±Elmer Differential Scanning Calorimeter,
DSC7.
2.2. X-ray data collection, structure solution and
re®nement
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 orientation on a
glass ®ber and data acquired with a Nonius MACH3
Four Circle Diffractometer ꢀ4PicTu4ClPh) or a
Nonius Kappa CCD Diffractometer ꢀ5PicTu4ClPh
and 6PicTu4ClPh), both at 130ꢀ2)8. The structures
were solved by direct methods and missing atoms
were found by difference-Fourier synthesis. The
non-hydrogen atoms were re®ned with anisotropic
temperature factors and hydrogens attached to nitro-
gens and carbons, except for methyl groups, were
found on a difference-Fourier map and re®ned isotro-
pically for 4PicTu4ClPh and 6PicTu4ClPh. The
hydrogens on carbons for 5PicTu4ClPh were ®xed
and allowed to ride on their parent atoms with a
Fig. 1. Representation of ꢀa) N-2-ꢀ3-picolyl)-; ꢀb) N-2-ꢀ4-picolyl)-;
ꢀc) N-2-ꢀ5-picolyl)- and ꢀd) N-2-ꢀ6-picolyl)-N0-4-chlorophe-
nylthiourea.
chlorophenylthiourea are weaker ꢀi.e. H´´´Cl distances
Ê
.3.00 A) [6], w0 e decided to extend our study to the four
N-2-picolyl-N -4-chlorophenylthioureas, 3PicTu4ClPh,
4PicTu4ClPh, 5PicTu4ClPh and 6PicTu4ClPh, Fig. 1.
2. Experimental
2.1. Preparative, spectral and thermal methods
4-Chlorophenyl isothiocyanate and the four 2-
aminopicolines were purchased from Aldrich and
ꢀ 2
®xed isotropic temperature factor, U ˆ 0:05 A :
Table 5
Melting points ꢀ8C), DHfus values ꢀkJ/mol) and selected H NMR assignments for the N-2-pyridyl-N0-4-chlorophenylthioureas
1
Thiourea
mp
DHfus
N3H ꢀN0H)
NH ꢀN2H)
C6H
CH3
References
PyTu4ClPh
188±190
117±119
186±187
200±201
190±192
226±227
34.3
16.8
35.2
51.1
40.1
66.5
13.91
13.96
13.73
14.60
14.04
14.11
8.32
8.25
8.30
8.18
8.36
8.26
7.84
8.06
8.04
7.93
[6]
3PicTu4ClPh
4PicTu4ClPh
5PicTu4ClPh
6PicTu4ClPh
4,6LutTu4ClPh
2.36
This work
This work
This work
This work
[9]
2.36
2.42
2.51
2.39, 2.23

L.F. Szczepura et al. / Journal of Molecular Structure 608 :2002) 245±251
247
Table 1
Crystallographic data and methods of data collection, solution and re®nement for 4PicTu4ClPh, 5PicTu4ClPh and 6PicTu4ClPh
Crystal data
4PicTu4Cl
C13H12ClN3S
Colorless, prism
0.25 £ 0.20 £ 0.12
293ꢀ2)
5PicTu4Cl
C13H12ClN3S
Colorless, needle
0.65 £ 0.05 £ 0.05
130ꢀ2)
6PicTu4Cl
C13H12ClN3S
Colorless, needle
0.16 £ 0.07 £ 0.05
130ꢀ2)
Empirical formula
Crystal color, habit
Crystal size ꢀmm3)
Temperature ꢀK)
Crystal system
Space group
Triclinic
Monoclinic
P21/cꢀ#14)
15.139ꢀ2)
4.8386ꢀ3)
17.338ꢀ2)
90
Monoclinic
C2/cꢀ#15)
33.520ꢀ6)
4.0750ꢀ3)
18.658ꢀ4)
90
P-1ꢀ#2)
Ê
a ꢀA)
7.5235ꢀ3)
9.1585ꢀ5)
10.5158ꢀ7)
76.015ꢀ3)
70.015ꢀ4)
82.010ꢀ4)
1309.8ꢀ2)
2
Ê
b ꢀA)
Ê
c ꢀA)
a ꢀ8)
b ꢀ8)
g ꢀ8)
90.661ꢀ4)
90
97.500ꢀ6)
90
Ê 3
Volume ꢀA )
Z
1270.0ꢀ2)
4
277.77
2526.8ꢀ7)
8
277.77
Formula weight
Density ꢀcalcd) ꢀg/cm3)
Absorp. coeff. ꢀmm21
277.77
1.399
1.453
1.460
)
0.432
0.449
0.451
Fꢀ000)
Index ranges
288
576
1152
28 # h # 8
210 # k # 10
212 # l # 12
2.64±24.71
3954
219 # h # 19
24 # k # 4
222 # l # 22
3.55±28.27
5026
0 # h # 38
24 # k # 4
221 # l # 21
3.07±24.79
2076
u range for data collection ꢀ8)
Total re¯ections
Independent re¯ects, Rint
Absorption correction
Max and min transmissions
Goodness-of-®t
2183, 0.0303
C-scan
3776, 0.1269
HKL-Scalepack
0.9770 and 0.7590
0.855
1328, 0.0852
HKL-Scalepack
0.9788 and 0.6711
0.867
0.9499 and 0.8996
1.017
Ê 3
Largest diff. peak ꢀe/A )
0.176
0.293
0.291
Ê 3
Largest diff. hole ꢀe/A )
R1, wR
20.214
0.0365, 0.0897
0.0594, 0.0993
20.284
0.0471, 0.0709
0.1461, 0.0879
20.291
0.0454, 0.0891
0.0836, 0.1000
R1, wR ꢀall re¯ections)
Fig. 3. ORTEP drawing showing 5PicTu4Cl with atom numbering
scheme and displacement ellipsoids at 50% probability level. The
disorder in the aryl ring is equally populated.
Fig. 2. ORTEP drawing showing 4PicTu4Cl with atom numbering
scheme and displacement ellipsoids at 50% probability level.

248
L.F. Szczepura et al. / Journal of Molecular Structure 608 :2002) 245±251
Fig. 4. ORTEP diagram showing 6PicTu4Cl with atom numbering scheme and displacement ellipsoids at 50% probability level.
DENZO [10] was used for data reduction and
scattering factors are from Wassmaire and Kirfel
[11]. The structures were solved with MaXus [12],
structure re®nement for the three thioureas was
carried out with SHELXL-97 and the graphics
used are Zortep [13]. Table 1 summarizes the
crystal data, collection information and re®nement
data for these thioureas.
3. Results and discussion
3.1. Structural studies
Table 2
The ORTEP diagrams of 4PicTu4ClPh,
5PicTu4ClPh and 6PicTu4ClPh are shown in
Figs. 2±4, respectively. Unfortunately, we were
unable to obtain suitable crystals for 3PicTu4ClPh.
4PicTu4ClPh, 5PicTu4ClPh and 6PicTu4ClPh all
crystallize with one unique molecule in the unit
cell, but even at low temperature there is disorder
ꢀi.e. equal population) in the aryl ring of
5PicTu4ClPh. The previously reported N-2-
Ê
Selected bond distances ꢀA) and angles ꢀ8) for 4PicTu4ClPh,
5PicTu4ClPh and 6PicTu4ClPh
Ê
Distances ꢀA) 4PicTu4Cl
5PicTu4Cl
6PicTu4Cl
S1±C7
N1±C2
N1±C6
C2±N2
N2±C7
N3±C7
N3±C8
C11±Cl1
1.674ꢀ2)
1.331ꢀ3)
1.344ꢀ3)
1.401ꢀ3)
1.370ꢀ2)
1.332ꢀ3)
1.434ꢀ3)
1.745ꢀ2)
1.682ꢀ3)
1.332ꢀ4)
1.343ꢀ3)
1.404ꢀ3)
1.369ꢀ4)
1.344ꢀ4)
1.414ꢀ3)
1.746ꢀ3)
1.674ꢀ3)
1.334ꢀ4)
1.358ꢀ4)
1.394ꢀ4)
1.376ꢀ4)
1.350ꢀ4)
1.410ꢀ4)
1.742ꢀ3)
pyridyl-N0-4-chlorophenylthiourea,
PyTu4ClPh,
crystallizes P-1 with two different molecules in
the unit cell [6] and N-2-ꢀ4,6-lutidyl)-N0-4-chloro-
phenylthiourea, 4,6LutTu4ClPh, C2/c with one
unique molecule [9] like 6PicTu4ClPh. Like
other pyridyl thioureas [2±9], 4PicTu4ClPh,
5PicTu4ClPh and 6PicTu4ClPh are found in a
conformation resulting fro0m intramolecular
hydrogen bonding of N3H ꢀN H) to the pyridine
nitrogen, N1, in a manner similar to the benzoyl
and acyl 0 thioureas [14±21] and `cis±cis' like N-
phenyl-N -phenylthiourea [22]. The three thioureas
have essentially the same bond distances, Table 2.
There are more differences among the bond
angles, particularly close to the thiourea moiety;
Angles ꢀ8)
C2±N1±C6
N1±C2±C3
N1±C2±N2
N2±C2±C3
C2±N2±C7
S1±C7±N2
N2±C7±N3
S1±C7±N3
C7±N3±C8
N3±C8±C9
N3±C8±C13
116.68ꢀ18)
123.36ꢀ19)
118.23ꢀ17)
118.42ꢀ19)
130.15ꢀ18)
119.63ꢀ16)
116.46ꢀ18)
123.90ꢀ15)
125.30ꢀ18)
121.10ꢀ19)
119.0ꢀ2)
117.3ꢀ3)
118.7ꢀ3)
123.0ꢀ3)
118.6ꢀ3)
118.4ꢀ3)
131.9ꢀ3)
118.1ꢀ2)
114.2ꢀ3)
127.7ꢀ2)
131.0ꢀ3)
126.7ꢀ3)
114.7ꢀ3)
123.0ꢀ3)
118.9ꢀ3)
118.1ꢀ3)
130.7ꢀ3)
118.4ꢀ2)
115.0ꢀ3)
126.5ꢀ2)
130.8ꢀ3)
117.7ꢀ4), 114.0ꢀ4)a
122.9ꢀ4), 127.5ꢀ4)b
a
N3±C8±C91 angle.
b
N3±C8±C131 angle.

L.F. Szczepura et al. / Journal of Molecular Structure 608 :2002) 245±251
249
Table 3
Intramolecular and intermolecular hydrogen bond distances ꢀA) and angles ꢀ8) for 4PicTu4ClPh, 5PicTu4ClPh and 6PicTu4ClPh, as well as C±
Ê
Ê
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
4PicTu4Cl
5PicTu4Cl
6PicTu4Cl
N3
N3
N3
N1
N1
N1
0.90ꢀ3)
0.86ꢀ3)
0.93ꢀ3)
1.92ꢀ2)
1.88ꢀ3)
1.80ꢀ3)
2.650ꢀ2)
2.633ꢀ3)
2.647ꢀ4)
137ꢀ2)
145ꢀ3)
149ꢀ3)
Intermolecular
4PicTu4Cla
N2
C3
C6
N2
C3
C91
N2
S1#1
S1#1
Cl1#2
S1#1
S1#1
Cl1#2
S1#1
0.92ꢀ3)
0.92ꢀ2)
0.98ꢀ2)
0.83ꢀ3)
0.95
2.49ꢀ3)
2.97ꢀ2)
2.96ꢀ2)
2.61ꢀ3)
2.81
3.383ꢀ2)
3.729ꢀ2)
3.585ꢀ2)
3.411ꢀ3)
3.612ꢀ3)
3.594ꢀ6)
3.403ꢀ3)
165.0ꢀ19)
139.9ꢀ16)
122.5ꢀ16)
163ꢀ3)
5PicTu4Clb
143.2
0.95
0.82ꢀ3)
2.80
2.60ꢀ3)
142.1
6PicTu4Clc
164ꢀ3)
a
#1: 1 2 x, 2y, 2z; #2: 2 2 x, 2y, 1 2 z.
#1: 1 2 x, 1 2 y, 2 2 z; #2: 2 2 x, 1 2 y, 2 2 z.
#1: 1 2 x, y, 0.5 2 z; #2: 0.5 2 x, 20.5 1 y, 0.5 2 z.
b
c
for example, C7±N3±C8 is 125.30ꢀ18)8 for
4PicTu4ClPh, 130.8ꢀ3)8 for 5PicTu4ClPh and
131.0ꢀ3)8 for 6PicTu4ClPh.
interaction. However, the N3´´´N1 distances for the
corresponding N-2-ꢀ4-picolyl)- and N-2-ꢀ6-picolyl)-
0
Ê
N -phenylthioureas, 2.622ꢀ4) and 2.647ꢀ3) A [7], indi-
cate that other factors in¯uence this interaction. For
thioureas with pyridine rings the angle for the N3±
H3´´´N1 interaction ranges between 135 and 1508 [2±
The
non-bonding
N3´´´N1
distance
for
Ê
5PicTu4ClPh, 2.633ꢀ3) A, is less than for the other
two thioureas of this study, which are both closer to
Ê
the average of 2.669ꢀ6) A for PyTu4ClPh [6] and
Ê
2.652ꢀ2) A for 4LutTu4ClPh [9]. These non-bonding
4,6±9,23,24]
5PicTu4ClPh and 6PicTu4ClPh.
as
found
for
4PicTu4ClPh,
distances of 4PicTu4ClPh and 6PicTu4ClPh are
somewhat longer than the analogous N-2-ꢀ4-picolyl)-
[23] and N-2-ꢀ6-picolyl)-N0-4-tolylthioureas [24],
Ê
2.630ꢀ3) and 2.623ꢀ2) A, indicating a difference in
the electronic effect by the aryl substituent on this
The intermolecular N2H2´´´S1 interaction is present
in thioureaswith intramolecularhydrogenbonding to an
oxygen [14±21] or nitrogen atom [2±9], as well as
thioureas without intramolecular hydrogen bonding
[22,25±28]. The N2´´´S1 non-bonding distances show
Table 4
Mean plane data and angles between planes for 4PicTu4ClPh, 5PicTu4ClPh and 6PicTu4ClPh
Compound Plane
Plane Mean plane deviation Atom with greatest deviation Plane/plane Angle
4PicTu4Cl N1±C2±C3±C4±C5±C6
N2±C7±S1±N3
1
2
3
1
2
3
4
0.0081
0.0051
0.0076
0.0066
0.0015
0.0255
0.0023
C5, 0.0098ꢀ0.0016)
N2, 0.0067ꢀ0.0013)
C10, 0.0118ꢀ0.0018)
C2, 0.0098ꢀ0.0019)
C7, 0.0025ꢀ0.0023)
C11, 0.0426ꢀ0.0041)
C121, 0.0034ꢀ0.0048)
2/1
3/2
1/3
2/1
3/2
1/3
3/4
12.77ꢀ0.21)
67.79ꢀ0.10)
62.30ꢀ0.07)
4.81ꢀ0.14)
28.98ꢀ0.22)
30.24ꢀ0.21)
47.85ꢀ0.23)
C8±C9±C10±C11±C12±C13
5PicTu4Cl N1±C2±C3±C4±C5±C6
N2±C7±S1±N3
C8±C9±C10±C11±C12±C13
C8±C91±C101±C11±C121±
C131
6PicTu4Cl N1±C2±C3±C4±C5±C6
N2±C7±S1±N3
1
2
3
0.0040
0.0018
0.0014
C6, 0.0054ꢀ0.0019)
C7, 0.0032ꢀ0.0021)
C9, 0.0023ꢀ0.0015)
2/1
3/2
1/3
7.55ꢀ0.13)
7.98ꢀ0.14)
7.12ꢀ0.15)
C8±C9±C10±C11±C12±C13

250
L.F. Szczepura et al. / Journal of Molecular Structure 608 :2002) 245±251
small differences for the present thioureas, but all
Ê
three are larger than PyTu4ClPh, 3.413ꢀ5) A [6],
Ê
and smaller than 3.465ꢀ2) A for 4,6LutTu4ClPh [9],
suggesting a steric effect due to the methyl groupꢀs)
on the pyridine ring.
Like other N-2-pyridyl-N0-arylthioureas [6±
9,27,28], 4PicTu4ClPh and 5PicTu4ClPh have a
weak interaction, C3±H3´´´S1; the interaction is
weaker in 6PicTu4ClPh with a H3´´´S distance of
Ê
3.08ꢀ3) A. S1 is positioned almost equally between
C3 and N2 of another molecule and the C3´´´S1 and
Ê
H3´´´S1 distances are often ca. 0.2 A longer than the
corresponding distances of the N2H20´´´S1 interaction.
Of note is that N-ꢀ3-picolyl)-N -phenylthiourea,
3PicTuPh, in which the methyl group in the 3-position
sterically hinders the N2±H2´´´S1 interaction, has a
due to melting, and values for DHfus are shown in
Table 5 along with their melting points. Data for N-
ꢀ2-pyridyl)-N0-4-chlorophenylthiourea, PyTu4ClPh
[6],
and
N-2-ꢀ4,6-lutidyl)-N0-4-chloro-
phenylthiourea, 4,6LutTu4ClPh [9] are included.
The very low value for 3PicTu4ClPh is due to the 3-
methyl group reducing the strength of the N±H´´´S
interaction. Similarly, the DHfus for N-2-ꢀ3-picolyl)-
N0-phenylthiourea is 21.3 kJ/mol 0 compared to
43.5 kJ/mol for N-2-ꢀ6-picolyl)-N0-phenylthiourea
[7]. In addition, N-2-ꢀ3-picolyl)-N -4-tolylthiourea
[23], N-2-ꢀ4-picolyl)-N0-4-tolylthiourea [23], and N-
2-ꢀ6-picolyl)-N0-4-tolylthiourea [24], have DHfus
values of 22.5, 44.6 and 47.2 kJ/mol, respectively.
These data con®rm that blocking the 3-methyl posi-
tion of the pyridine ring reduces the strength of the
intermolecular N2±H´´´S1 interaction and also, the
weak C3±H´´´S1 interaction is absent.
Ê
very long H2´´´S1 distance, an average of 3.09 A [7].
The comparatively low melting point and DHfus ꢀvide
infra) for 3PicTu4ClPh suggests weak intermolecular
interaction and probably contributes to our inability to
acquire a suitable crystal. Other C±H´´´X interactions
Since the tolyl analogues [23,24] of 3PicTu4Cl,
4PicTu4Cl and 6PicTu4Cl all have higher DHfus
values, the C±H´´´Cl interactions listed in Table 3
do not have much affect on the intermolecular attrac-
tions of the present molecules. However, for N-2-ꢀ4,6-
Ê
in which a hydrogen is within less than 3.00 A of X
and the angle is above 1108 are listed in Table 3.
The data for the mean planes is shown in Table 4
and there is a considerable difference in the planarity
of the three molecules. The angle between the mean
planes of the pyridyl and aryl ring, as a measure of
planarity, is a useful parameter. This is particularly
true since the angle between the mean planes of the
pyridine ring and the thiourea moiety do not show
large variation; they have been found to be less than
158 for the N-2-pyridyl-N0-arylthioureas studied to
date [2±9,23,24]. 6PicTu4ClPh is quite planar
although less planar than 4,6LutTu4ClPh, which has
an angle between the mean planes of the two rings of
less than 58 [9]. In contrast, the angle between the
rings in 4PicTu4ClPh is similar to the average for
the two unique molecules of PyTu4ClPh, ca. 608 [6]
and 5PicTu4Cl falls in between at about 308. The
disorder of the aryl ring in 5PicTu4Cl has 50% occu-
pancy for each form. One of the rings has a C±H
lutidyl)-N0-phenylthiourea, 4,6LutTuPh, DHfus
ˆ
50:9 kJ=mol and is far less than found for
4,6LutTu4ClPh, DHfus ˆ 66:5 kJ=mol [9]. Therefore,
other factors besides the dominant N2±H´´´S interac-
tion have an effect on the packing of these molecules
and their enthalpies of fusion. These other factors
include the number of molecules in the unit cell and
the planarity of the molecule; in general, the more
planar molecules have higher DHfus values. The
melting points listed in Table 5 are consistent with
these same conclusions.
3.3. NMR spectral studies
The 1H NMR signals, Table 5, show little change in
chemical shift for the thioureas of this study. The
down®eld position of N3H is consistent with its
involvement in intramolecular hydrogen bonding in
solution. The presence of a methyl group in the
6-position on the pyridyl ring in a previous study
ꢀi.e. 6PicTuPh and 4,6LutTuPh) [7] was found to
provide shielding to the N3H resonance due to the
diamagnetic anisotropic effect of the C6±CH3 bond.
Therefore, it is expected that the N3H resonance will
be found further down®eld in thioureas without a
Ê
within less than 3.0 A of a Cl1 of neighboring mole-
cule, Table 3, while the other ring has the analogous
Ê
CH greater than 3.0 A from a neighboring Cl1.
3.2. Thermal studies
The DSC plots of these thioureas show a sharp peak

L.F. Szczepura et al. / Journal of Molecular Structure 608 :2002) 245±251
251
[6] L.F. Szczepura, K.K. Eilts, A.K. Hermetet, L.J. Ackerman,
J.K. Swearingen, D.X. West, J. Mol. Struct. ꢀ2002) in press.
6-methyl substituent, but this is only true for
5PicTu4Cl of this study.
Â
Â
Â
Â
[7] J. Valdes-Martõnez, S. Hernandez-Ortega, G. Espinosa-Perez,
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. In press.
4. Conclusions
[8] D.X. West, J.K. Swearingen, A.K. Hermetet, L.J. Ackerman,
J. Mol. Struct. 562 ꢀ2001) 95.
The difference in the planarity of the three mole-
cules is striking, although not unexpected, given the
difference between PyTu4Cl [6] and 4,6LutTu4Cl [9]
noted earlier. The longer distance for C3H3´´´S1 in
6PicTu4Cl is in agreement with earlier ®ndings for
4,6LutTu4Cl, which also has the H3´´´S1 distance
[9] A.K. Hermetet, L.J. Ackerman, K.K. Eilts, T.K. Johnson, J.K.
Swearingen, J.M. Giesen, K.I. Goldberg, W. Kaminsky, D.X.
West, J. Mol. Struct. ꢀ2002) in press.
[10] Z. Otinowksi, W. Minor, Processing of X-ray diffraction data
collected in oscillation mode, Meth. Enzymol. 276 ꢀ1995)
307.
Ê
above 3.00 A [9]. The very low values for the DHfus
[11] D. Wassmaier, A. Kirfel, Acta Cryst. A51 ꢀ1995) 416.
[12] S. Mackay, C. Edwards, A. Henderson, C. Gilmore, N.
Stewart, K. Shankland, A. Donald. University of Glasgow,
Scotland, MaXus, 1997.
and melting point for 3PicTu4Cl is consistent wit0h
results found for other 3-substituted N-2-pyridyl-N -
phenylthioureas [23] and makes it dif®cult to acquire
suitable crystals for structural study.
[13] L. Zsolnai, G. Huttner. ZORTEP, University of Heidelberg,
Germany, 1994.
Supplementary material: Crystallographic data
ꢀexcluding structure factors) for the structures
reported in this paper have been deposited with the
Cambridge Crystallographic Data Center as supple-
mentary publication no. CCDC-167228 for
4PicTu4ClPh, CCDC-167229 for 5PicTu4ClPh, and
CCDC-167230 for 6PicTu4ClPh. Copies of available
material can be obtained, free of charge, on applica-
tion to the Director, CCDC, 12 Union Road,
Cambridge CB21EZ, UK ꢀfax: 144-ꢀ0) 1223-
336033 or e-mail: deposit@ccdc.cam.ac.uk).
[14] A. Dago, M.A. Simonov, E.A. Pobedimskaya, A. Macias, A.
Â
Martõn, Kristallogra®ya 32 ꢀ1987) 1024.
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Â
Martõn, Kristallogra®ya 33 ꢀ1988) 1021.
Â
[16] A. Dago, Y. Shepelev, F. Fajardo, F. Alvarez, R. Pomes, Acta
Cryst. C45 ꢀ1989) 1192.
[17] K.R. Koch, C. Sacht, S. Bourne, Inorg. Chim. Acta 232 ꢀ1995)
109.
[18] D.-C. Zhang, Y.-Q. Zhang, Y. Cao, B. Zhao, Acta Cryst. C52
ꢀ1996) 1716.
[19] Y. Cao, B. Zhao, Y.-Q. Zhang, D.-C. Zhang, Acta Cryst. C52
ꢀ1996) 1772.
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Acknowledgements
[22] A. Ramnathan, K. Sivakumar, K. Subramanian, N.
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Acknowledgement is made to the Camille and Henry
Dreyfus Foundation and the Donors of the Petroleum
Research Fund, administered by the American
Chemical Society, for the partial support of this
research.
Â
Â
Â
[23] J. Valdes-Martõnez, S. Hernandez-Ortega, A.K. Hermetet, L.J.
Ackerman, C.A. Presto, J.K. Swearingen, D.R. Kelman, K.I.
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submitted.
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D.R. Kelman, J.M. Giesen, K.I. Goldberg, W. Kaminsky, D.X.
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