Synthesis, spectroscopic characterization, mass spectrometry, and crystal structure of N-{[(4-bromophenyl)amino]carbonothioyl}benzamide

Article abstract of DOI:10.3906/kim-0912-415

N-{[(4-bromophenyl)amino]carbonothioyl}benzamide was synthesized and characterized by IR, ¹H- and ¹³ C-NMR, mass spectrometry, and elemental analysis. The crystal structure was determined from single crystal X-ray diffraction data. It crystallizes in monoclinic space group P2 ₁ /n with unit cell dimensions a = 13.822(3) A, b = 5.927(2) A, c = 16.642(3) A, and β = 103.963(3) ° . There is a strong intramolecular hydrogen bond of the type N--HAO, with an HAO distance of 2.6129 (11) A. The mass fragmentation pattern is also discussed. TUeBITAK.

Full text of DOI:10.3906/kim-0912-415

Turk J Chem
34 (2010) , 761 – 770.
¨
˙
c
ꢀ TUBITAK
doi:10.3906/kim-0912-415
Synthesis, spectroscopic characterization, mass
spectrometry, and crystal structure of
N-{[(4-bromophenyl)amino]carbonothioyl}benzamide
Sohail SAEED1,∗, Naghmana RASHID1, Moazzam Hussain BHATTI1,
Peter G. JONES2
1Department of Chemistry, Research Complex, Allama Iqbal Open University,
Islamabad PAKISTAN
e-mail: sohail262001@yahoo.com, nrk chem@yahoo.com, moazzamhussain b@yahoo.com
2Institut fu¨r Anorganische und Analytische Chemie, Technische Universit¨at Braunschweig,
Postfach 3329, 38023 Braunschweig, GERMANY
e-mail: p.jones@tu-bs.de
Received 28.12.2009
N-{[(4-bromophenyl)amino]carbonothioyl}benzamide was synthesized and characterized by IR, 1 H- and
13 C-NMR, mass spectrometry, and elemental analysis. The crystal structure was determined from single
crystal X-ray diffraction data. It crystallizes in monoclinic space group P21 /n with unit cell dimensions a
◦
˚
˚
˚
= 13.822(3) A, b = 5.927(2) A, c = 16.642(3) A, and β = 103.963(3) . There is a strong intramolecular
˚
hydrogen bond of the type N HΛO, with an HΛO distance of 2.6129 (11) A. The mass fragmentation
pattern is also discussed.
Key Words: Thiourea derivative, X-ray structure determination, mass fragmentation
Introduction
Sulfur is an interesting element, in particular because of the variety of its compounds and the variety of bonding
types it is involved in. 1 It has a prominent bioorganic chemistry and a large number of enzymes and other
proteins such as iron sulfur proteins exhibit fantastic properties involving the sulfur atoms in them.2,3 It is an
∗Corresponding author
761

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
important element forming chains4 and, more interestingly, bridges in polymers and in a variety of composite
materials, giving rise to strength and resistance to aging.
Thiourea and its derivatives are an important class of organic compounds in which sulfur is the major
ligand atom, playing an important role in coordination chemistry with transition metals. Thiourea and its
derivatives have found extensive applications in the fields of medicine, agriculture, and analytical chemistry.
Substituted thioureas are an important class of compounds, precursors, or intermediates towards the synthesis of
a variety of heterocyclic systems such as imidazole-2-thiones,4 2-imino-1,3-thiazolines,5 pyrimidine-2-thiones,
and (benzothiazolyl)-4-quinazolinones. Thioureas are also known to exhibit a wide range of biological ac-
tivities including antiviral, antibacterial, antifungal, antitubercular, antithyroidal, herbicidal, and insecticidal
activities6 and as agrochemicals.7−12 Thioureas are also well known chelating agents for transition metals.8
N, N-Dialkyl-N’-benzoyl thioureas act as selective complexing agents for the enrichment of platinum metals
even from strongly interfacing matrixes. The complexes of thiourea derivatives also show various biological
activities.9
The thiourea derivatives containing amino functional groups are also known as epoxy resin curing
agent.13 As a part of our continuing interest in biologically active thiourea derivatives and their transition
metal complexes, we report a route for synthesis of these compounds by using tetrabutylammonium bromide as
phase transfer catalyst to augment the yield of products. Saeed and coworkers14−16 have reported a number of
N-aroyl-N’-arylthioureas based publications that are related to our article.
We became interested in the synthesis of N-aroyl-N’-arylthioureas as intermediates towards some het-
erocycles and for the systematic study of their bioactive complexes and epoxy resin curing agents. In this
article, we describe the crystal structure of N-{[(4-bromophenyl)amino]carbonothioyl}benzamide as a typical
representative of N-aroyl-N’-arylthioureas.
Results and discussion
The target compound was synthesized by a slight modification of our published procedures.14−16 The use of
phase transfer catalysts to agitate a heterogeneous reaction system is gaining recognition.17,18 In an attempt to
improve syntheses of the target substituted thiourea derivative by reacting isothiocyanates with nucleophiles,
we found that the use of tetrabutylammonium bromide (TBAB) as phase transfer catalyst (PTC) can afford
aroyl isothiocyanate in good yield. In this study, we conducted our reaction using tetrabutylammonium bromide
(TBAB) as phase transfer catalyst to synthesize the intermediate aroyl thiourea derivative.
The chemical structure and purity of the compound were proved using elemental analysis, and 1 H-NMR,
13 C-NMR, and FTIR spectroscopy. The 1 H-NMR data of the compound obtained in DMSO solution are
given in the Experimental section and are consistent with the structural results. The elemental analyses closely
corresponded to calculated values. The analytical and spectroscopic data are consistent with the proposed
structure.19 IR (KBr) spectra of the compound had strong absorptions at 3352 cm−1 for free N-H and 3212
cm−1 for assoc N-H, and displayed absorptions at 1685 cm−1 and 1142 cm−1 that were assigned to C=O and
C=S functions, respectively. The medium-strong υC=O band in the IR spectrum of the compound appeared at
1685 cm−1 , which is lower than that of the ordinary carbonyl absorption (1730 cm−1); this may be attributed
to the formation of hydrogen bonds. These results agree with the data in the literature.20
762

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
In 1 H-NMR, the compound exhibited broad signals at 12.95 and 12.03 ppm, which were assigned to the
N-H protons. 13 C-NMR showed peaks at about δ 168.2 and 181.0 for C=O (amide) and C=S (thioamide),
respectively. The mass spectrum showed the molecular ion peak at m/z 335. The fragment at m/z 121(5.5%)
was derived from the N-McLafferty rearrangement and the base peak at m/z 105 (100%) originated from the
aroyl cation (Scheme).
+
.
NH2
+
.
N
Br
O
C
N
Br
m/z 172 (10 %)
m/z 291 (7. 2 %)
+
.
Br
S
H
N
N
H
+
.
Br
O
m/z = 335 . 22 (15 %)
m/z 157 (3. 5 %)
S
+
.
C
N
+
+
.
.
NH
O
C
OH
+
Br
m/z 105 (100 %)
- CO
m/z 121 (5. 5 %)
m/z 213 (20 %)
+
.
m/z 78 (65 %)
Scheme. Mass fragmentation pattern of N-{[(4-bromophenyl)amino]carbonothioyl} benzamide.
The molecular structure of the title compound is shown in Figure 1. Crystallographic data and refinements
are presented in Table 1 and final atomic coordinates and equivalent isotropic displacement parameters appear
in Table 2; bond lengths, angles, and torsion angles are presented in Tables 3 and 4, respectively. The C1-S
˚
and C2-O bonds show a typical double bond character with bond lengths of 1.6684(10) and 1.2324(12) A,
˚
˚
˚
respectively. All of the C-N bonds, C1-N1 = 1.3415(13) A, C11-N1 = 1.4137 (13) A, C2-N2 = 1.3769 (13) A,
˚
and C1-N2= 1.3992 (13) A, also indicate a partial double bond character. The C1-N2 bond, due to its vicinity to
763

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
the carbonyl group, is slightly larger than the C1-N1 bond.21 These bond distances are in good agreement with
those observed in structures containing the N-benzoyl-N’-phenylthiourea moiety, as reported in the Cambridge
Structural Database.22 The packing is 3-dimensional, but a representative 2-dimensional view along the short
axis is given in Figure 2. One classical H bond N1-H01ΛO and 4 ”weak” H bonds of the form C-HΛX (X =
O, S, Br) are observed. Numerical details are given in Table 5.
Table 1. Crystal data and structure refinement for N-{[(4-bromophenyl) amino]carbonothioyl}benzamide.
CCDC
724599
Empirical formula
Formula weight
Crystal size
C14H11BrN2OS
335.22
0.25 X 0.20 X 0.15 mm3
Temperature
Wavelength
100 (2) K
˚
0.71073 A
Crystal System
Space group
Monoclinic
P21/c
˚
a= 13.8228 (3) A
Unit cell dimensions
α = 90o
b=5.9272 (2) A
β = 103.963 (3)o
γ = 90o
˚
˚
c= 16.6425(3) A
3
˚
Volume
1323.24(6) A
Density (calculated)
1.683 g/cm3
Theta range of data collection 2.52 to 31.51o
Max and min transmission
No of reflections measured
No of independent reflections
F (0 0 0)
1.00000 and 0.71403
81955
4397
672
Refinement method
Final R indices [I > 2α(I)]
R indices (all data)
Goodness-of-fit on F2
Maximum, Δ/σ
Full-matrix least square on F2
R1= 0.0168, wR2= 0.0437
R1= 0.0216, wR2= 0.0441
1.028
0.000
˚
0.430 e/A
3
(Δ/ρ)max
3
˚
-0.260 e/A
(Δ/ρ)min
Data collection program
Cell refinement program
Data reduction program
Structure solving program
Oxford Diffraction, 2008
CrysAlis CCD
CrysAlis RED
Sheldrick, 2008
Structure refinement program Sheldrick, 2008
764

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
4
2
3
˚
Table 2. Atomic coordinates (x 10 ) and equivalent isotropic displacement parameters (A x 10 ) for N-{[(4-
bromophenyl) amino] carbonothioyl}benzamide.
x
y
z
U(eq)
4845.9(1) -3040.6(2) 3191.3(1) 15.3(1)
739.1(2) 2065.6(5) 4673.5(2) 15.9(1)
Br
S
N (1) 2676.8(6) 3345.6(15) 5018.8(5) 12.7(2)
N (2) 1619.6(6) 5431.2(15) 5600.6(5) 12.6(2)
O
3219.9(5) 6730.9(13) 6032.9(5) 17.1(2)
C (1) 1739.6(7) 3618.4(17) 5094.9(6) 11.7(2)
C (2) 2341.6(7) 6803.3(17) 6072.4(6) 12.6(2)
C (11) 3104.0(7) 1769.1(16) 4568.0(6) 10.9(2)
C (12) 2704.8(7) -330.6(17) 4287.6(6) 12.7(2)
C (13) 3221.0(7) -1736.5(17) 3865.8(6) 12.9(2)
C (14) 4129.4(7) -1060.1(18) 3735.6(6) 11.9(2)
C (15) 4539.5(7) 1023.7(18) 4007.8(6) 12.7(2)
C (16) 4020.7(8) 2427.4(17) 4423.4(6) 12.4(2)
C (21) 2005.5(7) 8384.4(17) 6643.3(6) 12.2(2)
C (22) 1226.8(8) 7864.2(19) 7009.9(6) 15.2(2)
C (23) 971.7(8)
C (24) 1479.5(8)
9372(2)
7563.9(7) 19.5(2)
7742.3(7) 19.9(2)
11400(2)
C (25) 2263.0(9) 11906.7(18) 7383.7(7) 18.4(2)
C (26) 2532.7(8) 10394.4(18) 6840.3(6) 15.1(2)
Figure 1. An ORTEP drawing of N-{[(4-bromophenyl)amino]carbonothioyl}benzamide with displacement ellipsoids
plotted at 50% probability level. The dotted line shows the intramolecular H-bonding interaction.
765

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
◦
˚
Table 3. Bond lengths [A] and angles [ ] for N-{[(4-bromophenyl) amino] carbonothioyl} benzamide.
Bond Angles
C(1)-N(1)-C(11)
C(2)-N(2)-C(1)
N(1)-C(1)-N(2)
N (1)-C (1)-S
131.79(9)
128.45(9)
114.00(9)
127.97(8)
118.03(7)
122.47(9)
121.32(9)
116.20(9)
Bond Lengths
Br-C (14)
1.9006(10)
1.6684(10)
1.3415(13)
1.4137(13)
1.3769(13)
1.3992(13)
1.2324(12)
1.4865(14)
1.3952(13)
1.4011(14)
1.3921(14)
1.3841(14)
1.3886(14)
1.3871(14)
1.3938(14)
1.3938(14)
1.3893(15)
1.3877(16)
1.3895(17)
1.3868(15)
S-C (1)
N (2)-C (1)-S
N(1)-C(1)
O-C (2)-N (2)
O-C (2)-C (21)
N (2)-C (2)-C (21)
N(1)-C(11)
N(2)-C(2)
N(2)-C(1)
C (12)-C (11)-C (16) 119.47(9)
O-C(2)
C (12)-C (11)-N (1)
C (16)-C (11)-N (1)
125.80(9)
114.71(9)
C(2)-C(21)
C(11)-C(12)
C(11)-C(16)
C(12)-C(13)
C(13)-C(14)
C(14)-C(15)
C(15)-C(16)
C(21)-C(26)
C(21)-C(22)
C(22)-C(23)
C(23)-C(24)
C(24)-C(25)
C(25)-C(26)
C (13)-C (12)-C (11) 119.55(9)
C (14)-C (13)-C (12) 120.02(9)
C (13)-C (14)-C (15) 121.39(9)
C(13)-C(14)-Br
C(15)-C(14)-Br
119.50(8)
119.10(7)
118.47(9)
121.09(9)
120.09(9)
117.58(9)
122.26(9)
119.64(10)
120.20(11)
120.11(10)
120.03(10)
119.89(10)
C(16)-C(15)-C(14)
C(15)-C(16)-C(11)
C(26)-C(21)-C(22)
C(26)-C(21)-C(2)
C(22)-C(21)-C(2)
C(23)-C(22)-C(21)
C(24)-C(23)-C(22)
C(23)-C(24)-C(25)
C(26)-C(25)-C(24)
C(25)-C(26)-C(21)
Experimental protocols
Instrumentation
Melting point was recorded on Electrothermal IA9000 series digital melting point apparatus. The proton NMR
and 13 C spectra were recorded in DMSO-d6 solvent on a Jeol ECS-400 and 300 MHz spectrophotometer using
tetramethylsilane as an internal reference, respectively. The apparent resonance multiplicity is described as s
(singlet), br s (broad singlet), d (doublet), dd (doublet of doublets), t (triplet), q (quartet), and m (multiplet).
Infrared measurement was recorded in the range 400-4000 cm−1 on a Spectrum 2000 (Perkin Elmer). Elemental
analysis was carried out using a Perkin Elmer CHNS/O 2400. The mass spectrum was run on a Finnigan TSQ-
70 spectrometer (Finnigan, USA) at 70 eV). X-ray diffraction data were collected on an Oxford Diffraction
766

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
Xcalibur Nova diffractometer. Thin layer chromatography (TLC) analysis was carried out on 5 × 20 cm plates
coated with silica gel GF254 type 60 (25-250 mesh) using an ethyl acetate-petroleum ether mixture (1:2) as
solvent.
Table 4. Torsion angles [◦ ] for N-{[(4-bromophenyl)amino]carbonothioyl}benzamide.
C (11)-N (1)-C (1)-N (2)
C (11)-N (1)-C (1)-S
-179.23(9)
1.41(17)
C (2)-N (2)-C (1)-N (1)
C (2)-N (2)-C (1)-S
-6.10(15)
173.32(8)
8.22(16)
C (1)-N (2)-C (2)-O
C (1)-N (2)-C (2)-C (21)
C (1)-N (1)-C (11)-C (12)
C (1)-N (1)-C (11)-C (16)
C (16)-C (11)-C (12)-C (13)
N(1)-C(11)-C(12)-C(13)
C(11)-C(12)-C(13)-C(14)
C(12)-C(13)-C(14)-C(15)
C(12)-C(13)-C(14)-Br
C(13)-C(14)-C(15)-C(16)
Br-C(14)-C(15)-C(16)
C(14)-C(15)-C(16)-C(11)
C(12)-C(11)-C(16)-C(15)
N(1)-C(11)-C(16)-C(15)
O-C(2)-C(21)-C(26)
-171.35(9)
-21.25(17)
160.41(10)
-0.25(14)
-178.51(10)
0.77(14)
-0.90(15)
177.91(7)
0.50(15)
-178.32(7)
0.04(15)
-0.16(15)
178.30(9)
28.69(14)
-151.74(9)
-148.06(10)
31.52(14)
0.79(15)
N(2)-C(2)-C(21)-C(26)
O-C(2)-C(21)-C(22)
N(2)-C(2)-C(21)-C(22)
C(26)-C(21)-C(22)-C(23)
C(2)-C(21)-C(22)-C(23)
C(21)-C(22)-C(23)-C(24)
C(22)-C(23)-C(24)-C(25)
C(23)-C(24)-C(25)-C(26)
C(24)-C(25)-C(26)-C(21)
C(22)-C(21)-C(26)-C(25)
C(2)-C(21)-C(26)-C(25)
177.46(10)
0.96(16)
-1.68(17)
0.64(16)
1.12(15)
-1.83(15)
-178.65(9)
767

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
Table 5. Hydrogen bonds [A and ◦ ] for N-{[(4-bromophenyl)amino]carbonothioyl} benzamide.
˚
D-H...A
d (D-H) d (H...A) d (D...A) < (DHA)
0.879(14) 1.843(15) 2.6129(11) 145.1(12)
0.806(13) 2.747(13) 3.5102(9) 158.6(12)
N (1)-H (01)...O
N (2)-H (02)...S#1
C (15)-H (15)...O#2
C (26)-H (26)...Br#2
C (24)-H (24)...S#3
0.95
0.95
0.95
2.46
3.13
2.90
3.3866(12)
3.9604(11)
3.7137(12)
165.5
147.5
144.7
Symmetry transformations used to generate equivalent atoms:
#1 -x,-y+1,-z+1
#2 -x+1,-y+1,-z+1
#3 x,-y+3/2,z+1/2
Figure 2. Packing diagram of N-{[(4-bromophenyl) amino]carbonothioyl}benzamide. The dashed lines denoted the
C
H . . . O and N H . . . O hydrogen bonds. Non-hydrogen bonded H atoms have been omitted for clarity.
768

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
Synthesis
The synthetic starting material, reagents, and solvents were of analytical reagent grade or of the highest quality
commercially available and were purchased from Aldrich Chemical Co. and Merck Chemical Co. and were
dried when necessary. A solution of benzoyl chloride (1.40 g, 0.01 mol) in anhydrous acetone (80 mL) and 3%
tetrabutylammonium bromide (TBAB) in acetone was added dropwise to a suspension of ammonium thiocyanate
(0.76 g, 0.01 mol) in acetone (50 mL) and the reaction mixture was refluxed for 45 min. After cooling to room
temperature, a solution of the corresponding 2-bromoaniline (1.71 g, 0.01 mol) in acetone (25 mL) was added and
the resulting mixture refluxed for 1.5 h. The reaction mixture was poured into 5 times its volume of cold water,
whereupon the thiourea precipitated. The solid product was washed with water and purified by re-crystallization
from an ethanol-dichloromethane mixture (1:2). Elemental analysis for C14 H11 BrN2 OS (MW=335.22) in wt
% calc. C=62.1, H=3.28, N=8.36, S=9.55 and found to be C=62.12, H=3.34, N=8.18, S= 9.43. mp. 141-142
◦ C, yield 93%. IR (KBr pellet) in cm −1 : 3352 (free NH), 3212 (assoc. NH), 1685 (C=O), 1509 (benzene ring),
1142 (C=S), 1402 (C-N stretching); 1 H-NMR (400 MHz, DMSO-d6) in δ (ppm) and J (Hz): 12.95 (1H, br
s, NH), 12.03 (1H, br s, NH), 7.74 (2H, d, J = 8.1 Hz), 7.66 (2H, d, J = 6.7 Hz) and 7.36 (2H, d, J = 8.4
Hz), 7.30 (2H, d, J = 8.0; 13 C-NMR (300 MHz, DMSO-d6) in δ (ppm): 181.0 (C=S), 168.2 (C=O), 145.1(C),
143.3(C), 133.0 (C), 132.2 (C), 129.5 (2 CH), 128.6 (2 CH), 127.5 (4 CH); EI MS, m/z (%): 335 (15), 291 (7.2),
213 (20), 172 (10), 157 (3.5), 121 (5.5), 105 (100), 78 (65).
Single Crystal X-ray Crystallography
Crystal data: C14 H11 BrN2 OS, monoclinic, space group P 21 /n, a=13.8228(3), b =5.9272(2), c = 16.6425(3)
◦
3
A, β = 103.963(3) , V = 1323.24 A , T = 100 K, Z = 4, F (000) = 672, Dx = 1.683 g cm−3 , μ
˚
˚
= 4.0 mm−1
.
Single crystals suitable for X-ray diffraction studies were obtained by evaporation from a
dichloromethane/ethanol mixture. A colorless plate 0.25 × 0.20 × 0.15 mm3 was mounted on a glass fiber
in inert oil. Measurements were performed at 100 K on an Oxford Diffraction Xcalibur Nova diffractometer
with mirror-focused Cu-Kα radiation to 2θmax 152◦ (99.8% complete to 31.51◦ ). The data were corrected
for absorption using the multi-scan method. Of 81,955 intensities, 4397 were independent (Rint 0.0273). The
structure was solved by direct methods and refined by full-matrix least-squares techniques on F 2 using the
program SHELXL-97.23 The non-hydrogen atoms were refined anisotropically. NH hydrogens were refined
freely, other H atoms using a riding model. The final wR2 was 0.0437, with a conventional R1 of 0.0168, for
−3
˚
180 parameters; S = 1.028; max. Δρ 0.260 e A
.
Supplementary crystallographic data
Crystallographic data for the structure reported in this article have been deposited with Cambridge Crys-
tallographic Data Centre, CCDC 724599. Copies of this information may be obtained free of charge from
the Director, CCDC, 12 Union Road, Cambridge, CBZ IEZ, UK. Facsimile (44) 01223 336 033, E-mail:
deposit@ccdc.cam.ac.uk or http//www.ccdc.com.ac.uk/deposit.
769

Synthesis, spectroscopic characterization, mass spectrometry..., S. SAEED, et al.,
Acknowledgements
The authors are grateful to the National Engineering & Scientific Commission and Allama Iqbal Open University,
Islamabad, for providing the necessary lab and analytical facilities.
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