Spectroscopic characterization and crystal structure of cis-Bis(N-(2-benzoyl)-N′,N′-diphenylthioureato-k 2O,S)nickel(II)

Article abstract of DOI:10.1134/S0022476612050137

The title compound [Ni(C₂₀H₁₅N₂OS) ₂] is prepared by the reaction of metal acetate with the corresponding acylthiourea derivative. The complex is characterized by elemental analysis, IR, ¹H and ¹³C NMR, and its structure is determined by single crystal X-ray diffraction. The Ni(II) ion is coordinated by the S and O atoms of two N-benzoyl-N′,N′-diphenylthiourea ligands in a slightly distorted square-planar coordination geometry. The two O and two S atoms are mutually cis to each other. The substance crystallizes triclinic (P-1 space group) with cell dimensions a = 10.7262(9) A, b = 12.938(3) A, c = 14.2085(12) A, α = 74.650(4), β = 78.398(4), γ = 68.200(5), and two formula units in the unit cell. The structure is very close to the related N-(2-furoyl) Ni complex reported previously.

Full text of DOI:10.1134/S0022476612050137

Journal of Structural Chemistry. Vol. 53, No. 5, pp. 921-926, 2012
Original Russian Text Copyright © 2012 by H. Pérez, R. S. Corrêa, B. O’Reilly, A. M. Plutín, C. C. P. Silva, Y. P. Mascarenhas
SPECTROSCOPIC CHARACTERIZATION AND CRYSTAL
STRUCTURE OF cis-Bis(N-(2-BENZOYL)-Nꢀ,Nꢀ-
DIPHENYLTHIOUREATO-k2O,S)NICKEL(II)
H. Pérez,1 R. S. Corrêa,2 B. O’Reilly,3 A. M. Plutín,3
C. C. P. Silva,4 and Y. P. Mascarenhas4
UDC 548.73:541.49:546.74
©
The title compound [Ni(C20H15N2OS)2] is prepared by the reaction of metal acetate with the corresponding
1
acylthiourea derivative. The complex is characterized by elemental analysis, IR, H and 13C NMR, and its
structure is determined by single crystal X-ray diffraction. The Ni(II) ion is coordinated by the S and O
atoms of two N-benzoyl-Nꢀ,Nꢀ-diphenylthiourea ligands in a slightly distorted square-planar coordination
geometry. The two O and two S atoms are mutually cis to each other. The substance crystallizes triclinic
(P-1 space group) with cell dimensions a = 10.7262(9) Å, b = 12.938(3) Å, c = 14.2085(12) Å,
ꢁ = 74.650(4)ꢂ, ꢃ = 78.398(4)ꢂ, ꢄ = 68.200(5)ꢂ, and two formula units in the unit cell. The structure is very
close to the related N-(2-furoyl) Ni complex reported previously.
Keywords: nickel(II) complex, acylhiourea derivatives, spectroscopic analysis, crystal structure, molecular
assembly, Hirshfeld surface.
INTRODUCTION
In recent years, thiourea derivatives have been a subject of investigations because of their applications in analytical
and biological sciences, as well as due to their ability to form stable metal complexes [1]. A class of substituted thioureas
widely studied is known as N-acyl-Nꢀ,Nꢀ-dialkylthiourea, synthesized for the first time by Neucki in 1873 [2]. In the field of
coordination chemistry, N-acyl-Nꢀ,Nꢀ-dialkylthioureas coordinated with transition metals were first explored by Beyer and co-
workers [3] and later by König et al. [4]. Many N-acyl-Nꢀ,Nꢀ-disubstituted thiourea complexes involving metals such as
nickel, copper, cobalt, cadmium, palladium, platinum, and ruthenium have been studied, [5-10]. Thioureas coordinate to a
metal via both sulfur and oxygen providing a multitude of bonding possibilities [1, 11]. Over recent years, many transition
metal complexes with N-benzoyl-Nꢀ,Nꢀ-disubstituted thioureas have been reported [12-15] because this kind of ligands
display a remarkably rich coordination chemistry. Usually the ligand is coordinated to the metal center forming a very stable
bidentate complexe (cis conformation preferred) with a six-membered ring chelate structure, the complex stoichiometry
generally being 1:2 or 1:3 (M:L, with M = metal ion and L = ligand), according to the oxidation state of the metal ion.
The biological activities of complexes with thiourea derivatives have been successfully screened for various
biological actions. Metal complexes of these ligands containing oxygen and sulfur as donor atoms are known to possess
1Departamento de Química Inorgánica, Facultad de Química, Universidad de la Habana, Habana, Cuba;
2
3
hperez@fq.uh.cu. Departamento de Química, Universidade Federal de São Carlos, São Carlos, SP, Brasil. Laboratorio de
4
Síntesis Orgánica, Facultad de Química, Universidad de la Habana, Habana, Cuba. Grupo de Cristalografia, Instituto de
Física de São Carlos, Universidade de São Paulo, SP, Brasil. The text was submitted by the authors in English. Zhurnal
Strukturnoi Khimii, Vol. 53, No. 5, pp. 941-945, September-October, 2012. Original article submitted November 5, 2011.
0022-4766/12/5305-0921
921

useful activities as anti-tumor, anti-fungal, anti-bacterial, insecticidal, herbicidal, pesticidal reagents and plant-growth
regulators [16, 17].
We have recently begun to examine the coordination behavior of a series of substituted acylthiourea derivatives [5-
7, 13-15]. In this paper, we study the binding of N-benzoyl-N′,N′-diphenylthiourea to the Ni(II) ion. The complex was
1 13
characterized by the elemental analysis, IR, H and C NMR spectra, and X-ray structural analysis.
EXPERIMENTAL
All reagents and solvents used were purchased from commercial sources of analytical grade. Elemental analysis (C,
H, N, and S) were performed on a Perkin-Elmer 2400 CHN instrument. The infrared spectrum was recorded on a Nicolet
1 13
NEXUS 670 IR spectrophotometer using KBr discs. H and C NMR spectra were recorded on an Advance 300 Bruker
spectrometer with CDCl as the solvent at frequencies of 250 MHz and 62.9 MHz respectively, using TMS as the standard.
3
13
The assignment of the signals in the C NMR spectra was supported by the DEPT-135° spectrum.
Synthesis of the complex. N-benzoyl-N′,N′-diphenylthiourea ligand was synthesized by converting benzoyl chloride
into benzoyl isothiocyanate and then condensing with an appropriate amine [18]. To an ethanol solution (30 ml) containing the
ligand (0.66 g, 2 mmol) was added an ethanol solution of Ni(CH ∼ COO) ∼ 4H O (0.25 g, 1 mmol). The solution was stirred at
3
2
2
room temperature for 2 h, and at once a solution of NaOH (1 N) was added to adjust pH to the neutral value. The mixture was
filtered and the filtrate was evaporated under reduced pressure to give a red solid that was washed with acetone. Suitable X-ray
quality crystals were obtained by slow evaporation of a chloroform/hexane solution (1:1, v/v) of the complex.
2
cis-Bis(N-(2-benzoyl)-N′,N′-diphenylthioureato-k O,S)nickel(II). Brown. Yield, 74.0%. TF (°C), 276-277. Anal.
Calc. for C H N NiO S (%): C, 66.59; H, 4.19; N, 7.76; S, 8.89. Found: C, 66.46; H, 4.15; N, 7.81; S, 8.95. IR (KBr):
40 30 4 2 2
–1 1
ν = 3060 (CH), 3028 (CH), 1587 (C=C), 1513, 1417 (CN), 1254 (CS) cm . H NMR (CDCl ), ppm: δ = 7.22-7.25 (m, 4H,Ph);
3
13
7.28 (d, J = 7.93 Hz, 1H, Ph); 7.33 (d, J = 7.32 Hz, 1H); 7.35-7.43 (m, 2H, Ph); 7.76 (d, J = 6.66 Hz, 2H, Ph); C NMR
(CDCl ), ppm: 127.10, 128.56, 129.12, 129.49, 131.18, 131.63, 136.37, 136.45, 142.96 (C–Ph); 173.71 (CO); 175.48 (CS).
3
X-ray crystallography. X-ray diffraction data collection of the complex was performed on an Enraf-Nonius
Kappa–CCD diffractometer (95 mm CCD camera on a ϕ-goniostat) using graphite-monochromated MoK radiation
α
(0.71073 Å). The final unit cell parameters were based on all reflections. Data collections were carried out using the
COLLECT program [19]; integration and scaling of the reflections were performed with the HKL Denzo–Scalepack system
of programs [20]. Gaussian absorption correction was applied [21]. The structure was solved by direct methods with
2
SHELXS-97 [22]. The model was refined by full-matrix least squares on F with SHELXL-97 [22]. All hydrogen atoms
were stereochemically positioned and refined with the riding model. The aromatic hydrogen atoms were set isotropic with a
thermal parameter 20% greater than the equivalent isotropic displacement parameter of the atom to which each one was
bonded. The WinGX [23] program was used to prepare the material for publication. Structural analysis and figures were
made using the ORTEP-3 [24] and MERCURY [25] softwares. The Cambridge Structural Database was used to compare the
structure of the complex with the others [26]. Further details concerning data collection and refinement are given in Table 1.
RESULTS AND DISCUSSION
–1
IR and NMR spectra. Regarding the IR spectra, the complex displays strong bands in the region of 1590-1250 cm ,
which are characteristic of N-benzoyl-N′,N′-diphenylthioureas and N-furoyl-N′,N′-diphenylthioureas [27]. No absorption was
–1
–1
detected, however, in the range between 1700 cm and 1650 cm , where the uncoordinated ligand is supposed to exhibit
C=O stretching vibrations [18]. This absorption shifts to lower frequencies is a clear proof of complex formation with a large
degree of electron delocalization within the chelate rings. N-benzoyl-N′,N′-diphenylthiourea show the N–H stretching band
–1
near 3200 cm , which is not present in the corresponding metal complex, in agreement with the presence of a deprotonated
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TABLE 1. Crystal Data and Structure Refinement Parameters Obtained for the Complex
Empirical formula
Formula weight
[NiC H N O S ]
40 30 4 2 2
721.51
Triclinic
P-1
Crystal system
Space group
Unit cell dimensions
a, b, c, Å; α, β, γ, deg
10.7262(9), 12.938(3), 14.2085(12);
74.650(4), 78.398(4), 68.200(5)
3
Volume, Å
1753.8(5)
Z
2
1.366
3
Density calculated, mg/cm
–1
0.713
μ, mm
F(000)
748
Crystal size, mm
0.072×0.042×0.031
3.11–25.00
θ range deg
Index ranges
–11 ≤ h ≤ 11, –14 ≤ k ≤ 14, –15 ≤ l ≤ 15
9392
Reflections collected
Independent reflections
5011 [R(int) = 0.0838]
99.4
Completeness to θ , %
max
Max. and min. transmission
Data/restraints/parameters
0.978 and 0.926
6179/0/442
2
GOOF on F
0.976
R1 = 0.0505, wR2 = 0.0910
R1 = 0.1102, wR2 = 0.1065
0.251 and –0.385
Final R indices [I > 2σ(I )]
R indices (all data)
–3
Δρ and Δρ , e⋅Å
max min
–1
–1
–1
ligand in this chelate. The bands that center near 1500 cm , 1400 cm , and 1250 cm can be attributed to absorptions of the
CN and CS groups engaged in partial double bonds and confirm the complex formation, while those bands are absent in the
IR spectra of the free ligand.
1
Additional support for the above assignments is obtained from the H NMR spectra of this complex. The
experimental NMR data of the complex correspond to those of similar compounds [28]. The absence of the singlet
corresponding to the proton of NH acylthioureide groups around 8.70 ppm [18] corroborates the coordination of the ligand to
13
metal through these groups. As far as C NMR spectra is concerned, the signals in 182.76 ppm (C=S) and 162.63 ppm
(C=O), typical of the free ligand, are absent. Two new peaks, assigned to quaternary carbon atoms, were found about
175.5 ppm (CS) and 173.7 ppm (CO) instead, which is in accordance with the proposed structure for the complex. The effects
of circulating π electrons of the chelate rings could account for the opposite displacements that have been found with respect
to the free ligand, especially in the carbon atoms corresponding to the thiocarbonyl and carbonyl groups, with shifts to lower
and higher frequencies respectively.
Single crystal X-ray analysis. The molecular structure of the complex showing the atom numbering scheme is
given in Fig. 1. Selected bond lengths and angles are listed in Table 2. In the structure, two N-benzoyl-N′,N′-diphenylthiourea
molecules are bonded to the central Ni(II) ion in cis positions. The coordination geometry is a slightly distorted square-plane
as reflected by O1–Ni1–S2 and O2–Ni1–S1 bond angles (Table 2). The dihedral angle between S1–Ni1–O1 and S2–Ni1–O2
planes is 5.1(2)°.
The Ni–S (1.862(3) Å and 1.865(3) Å) bond distances are equal within experimental error [26]. The Ni–S and Ni–O
bond lengths lie within the range of those found in the related structures [5, 14]. The distance of the nickel atom from the best
plane through the coordination sphere is –0.013(1) Å. The chelate ring systems Ni1–O1–C1–N1–C2–S1 and Ni1–O2–C21–
N3–C22–S2 are nearly planar with the largest deviations from the best plane being 0.047(2) Å for O1 and –0.037(3) Å for O2
923

Fig. 1. Molecular structure of the title compound with
selected atoms labeled. Displacement ellipsoids are
drawn at the 30% probability level.
TABLE 2. Selected Bond Lengths and Angles (Å, deg) for the Complex
Ni1–O1
Ni1–O2
Ni1–S1
Ni1–S2
1.862(3)
1.865(3)
C1–O1
C1–N1
C1–C3
1.255(4)
1.332(4)
1.478(5)
C2–N1
C2–N2
C2–S1
1.330(4)
1.362(4)
1.720(4)
2.1445(11)
2.1530(11)
O1–Ni1–O2
O1–Ni1–S1
83.36(11)
95.57(8)
O2–Ni1–S1
O1–Ni1–S2
176.66(9)
175.57(9)
O2–Ni1–S2
S1– Ni1–S2
95.68(9)
85.62(4)
respectively. The dihedral angle between these chelate planes is 6.66(13)°. The molecular structure is very close to the related
N-(2-furoyl) Ni complex reported previously [5], and shows a dihedral angle of 28.1(2)° between the phenyl planes of the
benzoyl groups, in comparison with the corresponding angle of 24.2(2)° between the furanic planes of the furoyl Ni complex.
The lengths of C–O, C–S, and C–N bonds in the chelate ring are between characteristic single and double bond
lengths [26], which are shorter than single and longer than double bonds. These results can be explained by the existence of
delocalization in the chelate ring, which is also supported by IR and NMR data. Fig. 2 shows the packing arrangement of the
complex with two molecules in the unit cell. The crystal assembly of this complex is formed by sheets along the [111]
direction (Fig. 3). To stabilize the structure there are weak non-classical C…H–C intermolecular interactions, such as van der
Waals forces and π–π stacking. It is known that the non-classical interactions can provide good structural motifs for the
construction of extended architectures and stabilize the crystal structures of Ni(II) complexes [29].
These weak intermolecular interactions of the complex were analyzed using the Hirshfeld surfaces and the
corresponding 2D fingerprint plots [30]. The d
(normalized contact distance) surface and the breakdown of the fingerprint
norm
plots (new techniques and tools incorporated in the CrystalExplorer computer program [31]) were used for decoding and
quantifying the intermolecular interactions in the crystal lattice. From this analysis, it immediately emerges that the title
compound noticeably contributes to C…H–C interactions (35.9% Hirshfeld surface area), more than other contacts, as
obtained from the crystal structure of the complex.
The authors thank the Grupo de Cristalografia, IFSC, USP, Brasil for allowing the X-ray data collection and
Professor J. Ellena for helpful discussion. The authors acknowledge the financial support from the Ph. D. Cooperative
Program — ICTP/CLAF and the Brazilian agencies: FAPESP, CNPq and Capes. RSC acknowledges FAPESP (2009/08131-1)
for a PhD fellowship.
924

Fig. 2. View of the unit cell of the title complex.
Fig. 3. Crystal packing representation with the
molecules forming sheets along the [111] direction.
Supplementary material. Crystallographic data for the structure reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre, CCDC No. 816028. Copies of this information may be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: (internat.) +44-1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk].
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