Synthesis, crystal structure, and biological activity of a new Cu(I) complex of the N-phenyl-N′-(2-nitrobenzoyl)-thiourea

Article abstract of DOI:10.1080/10426501003752187

The complex bis(-sulfur)-sulfur-[N-phenyl-N′-(2-nitrobenzoyl)- thiourea]copper (I) was obtained from the reaction between the N-phenyl-N′-(2-nitrobenzoyl)-thiourea(HL) and copper(II). The compound was characterized by IR and 1H NMR, 13C NMR spectroscopy a

Full text of DOI:10.1080/10426501003752187

Phosphorus, Sulfur, and Silicon, 185:2558–2562, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426501003752187
SYNTHESIS, CRYSTAL STRUCTURE, AND BIOLOGICAL
ACTIVITY OF A NEW Cu(I) COMPLEX OF THE
N-PHENYL-Nꢀ-(2-NITROBENZOYL)-THIOUREA
Jing-Han Hu,1 Xiao Hui Fan,1 Xiao-Li Du,2 and Tai-Bao Wei2
1College of Chemical and Biological Engineering, Lanzhou Jiaotong University,
Lanzhou, Gansu, P. R. China
2College of Chemistry and Chemical Engineering, Northwest Normal University,
Lanzhou, Gansu, P. R. China
The complex bis(µ-sulfur)-sulfur-[N-phenyl-Nꢀ-(2-nitrobenzoyl)-thiourea]copper (I) was
obtained from the reaction between the N-phenyl-Nꢀ-(2-nitrobenzoyl)-thiourea(HL) and
1
copper(II). The compound was characterized by IR and H NMR, 13C NMR spectroscopy
and its structure was determined by single crystal X-ray diffraction. The complex is binuclear
with two copper(I) ions coordinated by a terminal sulfur, two bridging sulfurs, and a HL
molecule. In addition, the compound is also a considerable plant-growth regulator.
Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental
file.
Keywords Biological activity; copper(I) complex; sulfur-bridging complexes; thiourea
INTRODUCTION
Acyl thiourea derivatives have many biological activities. For example, they have
been used as bactericides, fungicides, and insecticides in many plants1,2 and as plant-growth
regulators.3 Moreover, thioureas are potentially very versatile ligands, as they are able to
coordinate to a range of metal centers as either neutral ligands,4 monoanions,5 or dianions.6
In recent years, many N-substituted thioureas have been extensively used as ligands in
the synthesis of metal complexes.7–9 In these complexes, thiourea and its derivatives are
coordinated to a metal ion either by the N or S atoms, by both of them, or by other donor
atoms available in the molecule. In addition, the different donor atoms as well as the various
structures of thiourea derivatives result in a variety of complexes.10–12 In continuation of our
earlier work,13–16 we report in this article the synthesis and characterization of the complex
formed by the reaction of copper(II) with N-substituted thiourea ligands via S atoms. In
Received 19 January 2010; accepted 5 March 2010.
We gratefully acknowledge the support of the colleges and universities graduate advisor research project in
Gansu Province (No. 0804-11) and the National Natural Science Foundation of China (No. 20671077).
Address correspondence to Jing-Han Hu, College of Chemical and Biological Engineering, Lanzhou Jiaotong
University, Lanzhou, Gansu, 730070, P. R. China. E-mail: hujinghan62@163.com
2558

NEW Cu(I) COMPLEX
2559
addition, the crystal structure of the complexes in this work shows the N-phenyl-Nꢁ- (2-
nitrobenzoyl)-thiourea ligand to display an unusual coordination mode to Cu(I). Finally,
by investigating the biological activity of the title compound, we found that the compound
has high plant-growth regulating activity at low concentration.
RESULTS AND DISCUSSION
Spectroscopic Properties
The IR spectrum of the title complex shows two bands at 3443 and 3144 cm−1, which
are attributed to the two stretching frequencies υ(N H). A strong band at 1687 cm−1 is
assigned to the υ(C O) vibration. A strong band at 1169 cm−1 is ascribed to the thionyl
group, which has a 89 cm−1 red shift compared with 1258 cm−1 in free thiourea, indicating
coordination of the thionyl group with copper(I). The IR spectra of the title complex are
consistent with the structure of the title compound.
Crystal Structure
The preparation of the ligand is shown in Scheme 1. The crystal structure of the title
compound was shown in Figure 1. The crystal data and structure refinement details for
C28H22ClCuN6O6S2 are summarized in Table I, and selected bond distances and angles are
listed in Table II.
O
O
PEG-400
+
KSCN
CH2Cl2 / r.t.
N C S
Cl
NO2
NO2
2
1
O
S
NH2
N
N
H
H
CH2Cl2 / r.t.
NO2
3
Scheme 1
The molecular structure of the dimer [{Cu(HL)2Cl}2] is shown in Figure 1. The
copper(I) complex was obtained from the reaction between the ligand and copper(II), to-
gether with the atom numbering scheme used. Each copper(I) ion is bonded to one chloride
and three sulfur atoms, which come from one terminal and two bridging acylthiourea
ligands, displaying a distorted tetrahedral geometry. The two copper(I) ions and the bridg-
ing sulfur atoms form a strictly planar Cu2-S2 core with two short [2.315 Å] and two
longer Cu S distances [2.599 Å]. The short one is nearly the same as the sum of the
tetrahedral covalent radii (2.39 Å).17 The core also contains a relatively longer Cu. . . Cu
separation of 3.523 Å, a narrow bridging S Cu S angle of 88.61, and a wide Cu S Cu
angle of 91.39. The dihedral angle (66.90◦) between the core and the remaining coordina-
tion plane, Cl(1)Cu(1)S(1) or Cl(1ꢁ)Cu(1ꢁ)S(1ꢁ), is smaller than the right angle (90◦) of a

2560
J.-H. HU ET AL.
Figure 1 The structure of {Cu(HL)2Cl}2.
normal tetrahedron, indicating a rather distorted tetrahedral co-ordination geometry around
copper(I). In the complex the ligands (HL) are co-ordinated to the copper(I) ions only
through the unidentate S atom; the acyl oxygen atoms do not take part in co-ordination but
form intermolecular hydrogen bonds C H. . . O with the cyclopentadienyl ring of the other
Table I The crystal data of the title compound [{Cu(HL)2Cl}2]
Formula
C28H22ClCuN6O6S2
Fw
701.63
Crystal system
Triclinic
Space group
P1
a/◦
8.3436(10)
13.2043(15)
14.8885(18)
108.843(5)
97.962(6)
98.449(5)
1504.9(3), 2
716
b/◦
c/◦
α/◦
β/◦
γ /◦
V/Å3, Z
F (000)
Reflections collected/unique (Rint
Obsd reflns [I ≥ 2σ(I)]
D
)
8653/5845 [R(int) = 0.0143]
5845
5845/0/413
1.548
1.006
1.027
0.0345, 0.0829
Dc/Mg·m−3
µ/mm−1
Goodness-of-fit on F2
R1,a wR2b [I ≥ 2σ(I)]

NEW Cu(I) COMPLEX
2561
Table II Selected bond distances and bond angles (◦) for the compound
Bond lengths
Cu(1) S(2)
Cu(1) S(1)
S(1) Cu(1)#1
2.2587(6)
2.3153(6)
2.5995(8)
Cu(1) Cl(1)
Cu(1) S(1)#1
2.2892(7)
2.5994(7)
Bond angles
S(2) Cu(1) Cl(1)
Cl(1) Cu(1) S(1)
Cl(1) Cu(1) S(1) #1
C(7) S(1) Cu(1) #1
116.60(2)
S(2) Cu(1) S(1)
115.96(2)
116.12(3)
111.24(3)
103.73(8)
S(2) Cu(1) S(1) #1
S(1) Cu(1) S(1) #1
Cu(1) S(1) Cu(1) #1
103.57(2)
88.61(2)
91.39(2)
Symmetry transformations used to generate equivalent atoms: #1 –x + 2, –y + 2, –z + 1.
dimmer. In addition, there are two N H. . . Cl intermolecular interactions, N2 H2. . . Cl and
N5 H5. . . Cl, which stabilize the molecular conformation. Moreover, it also can be seen
that the crystals form a six-membered ring through one intermolecular hydrogen bond of
N2 H2N···Cl1. In addition, there are two intermolecular hydrogen bonds N4 H4N···O2i
and C11 H1. . . O8ii, that form a 2D network structure (Figure S1, Table S1 Supplemental
Materials, available online). It is interesting that the charge of copper changed from copper
(II) to copper (I). We had previously reported this phenomenon.16,18 It was found that the
portion of the ligand(HL) played the reducer role in the reaction and then the title compound
was obtained.
Biological Activity
We also investigated plant growth regulation activity. Here, we adopted the method
of plate culture. From the results summarized in Table S2 (Supplementary Materials),
compared with heteroauxing, the compound exhibited root elongation activity, and when
the concentration was decreased from 100 ppm to 0.001 ppm, the root elongation activity
becomes strengthener gradually. It was obvious that the compound showed excellent plant-
growth regulation activity in the concentration of 0.001 ppm, with which the growth activity
reached 40.0%.
EXPERIMENTAL
Material and Methods
Melting points were measured on an X-4 digital melting-point apparatus and were
uncorrected. The infrared spectra were performed on a Digilab FTS-3000 FT-IR spectropho-
tometer. 1H NMR and 13C NMR spectra were recorded on a Varian Mercury plus-400 MHz
spectrometer with DMSO as solvent and TMS as an internal reference. MS spectra were
obtained on a Waters ZQ 4000.
Synthesis of the N-Phenyl-Nꢀ-(2-nitrobenzoyl)-thiourea Ligand (HL)
Powdered potassium thiocyanate (7.5 mmol) 2-nitrobenzoyl chloride (5 mmol), PEG-
400 (3% with respect to ammonium thiocyanate), and dichloromethane 20 mL were placed
in a dry, round-bottomed flask containing a magnetic stirrer bar and stirred at room
temperature for 1 h. Then aniline (5 mmol) was added, and the mixture was stirred for
an additional 0.5 h. The corresponding thiourea precipitated immediately. The product was

2562
J.-H. HU ET AL.
filtered, washed with water to remove inorganic salts, dried, and recrystallized from DMF-
◦
1
EtOH-H2O to give the title compound. Yield, 78%; mp 179–181 C; H NMR (CDCl3,
400 MHz) δ: 12.28 (s, 1H, NH), 11.62 (s, H, NH), 7.24∼8.14(m, 9H, Ar H); 13C NMR
(CDCl3, 400 MHz) δ: 124.3, 125.0, 127.1, 128.3, 128.9, 130.0, 131.9, 134.3, 137.2, 145.8,
166.7, 177.9; ESI-MS: 301.7(m/z+1).IR (KBr, cm−1) υ: 3169, 3028 (NH), 1691 (C O),
1258(C S); Anal. Calc. for C14H11N3SO3: C: 55.80, H: 3.68, N: 13.95; Found C: 55.77,
H: 3.70, N: 13.97.
Preparation of the Complex {Cu(HL)2Cl}2
The ligand (5 mmol) was dissolved in DMF (5 mL). To this solution, CuCl2·2H2O
(2.5mmol) in EtOH (5 mL) was added. After stirring the solution at room temperature for 2 h,
the yellow precipitate was filtered and obtained. During the process, oxidation–reduction
reactions occurred.18 Single crystals were obtained in CH3CN after 1 month by slow
evaporation at room temperature. Anal. Calc. for C56H44Cl2Cu2N12O12S4: C: 47.93, H:
3.16, N: 11.98; Found C: 47.86, H: 3.01, N: 11.85.1H NMR (CDCl3, 400 MHz) δ:12.12 (s,
2H, NH) δ: 9.46 (s, 2H, NH) δ:7.26∼8.18 (m, 18H, Ar H) 13C NMR (CDCl3, 400 MHz)
124.3, 124.4, 125.4, 128.1, 129.3, 129.7, 131.5, 133.9, 136.0, 145.9, 168.4, 178.9.
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