5-Methyl-2-hydroxy-acetophenone-S-methyl-thiosemicarbazone and
its nickel-PPh
3
complex. Synthesis, characterization, and DFT
calculations
S¸ükriye Güveli
a,*, Is¸
ın Kılıç-Cıkla
b,**, Bahri Ülküseven
a, Metin Yavuz
c,
Tülay Bal-Demirci
aaDepartment of Chemistry, Engineering Faculty, Istanbul University-Cerrahpas¸a, 34320, Avcilar, Istanbul, Turkey bDepartment of General Secretary, Ondokuz Mayıs University, 55139, Kurupelit, Samsun, Turkey
cDepartment of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139, Kurupelit, Samsun, Turkey
a r t i c l e i n f o
Article history: Received 17 April 2018 Accepted 26 June 2018 Available online 27 June 2018 Keywords: Thiosemicarbazone Nickel(II) Triphenylphosphine X-ray diffraction DFT calculations
a b s t r a c t
A tridentate Schiff base ligand (5-methyl-2-hydroxy-acetophenone-S-methyl-thiosemicarbazone, H2L)
and its mononuclear nickel complex, [NiL(PPh3)], were obtained and characterized by spectroscopic
techniques. Structural analysis of the compounds was supported by complementing crystallographic studies. The X-ray data related to molecular geometries was used in the DFT/B3LYP calculations with 6-311G (d, p) and LANL2DZ (for nickel atom) basis sets. Atomic charge distribution data indicated that the negative charges of free thiosemicarbazidato ligand were transferred to nickel (II) by the formation of the metal complex. To understand the nucleophilic or electrophilic reaction capabilities the ligand and nickel complex, the molecular electrostatic potential (MEP) and electrostatic potential (ESP) analyses have performed.
© 2018 Elsevier B.V. All rights reserved.
1. Introduction
The condensation of thiosemicarbazide with a carbonyl com-pound results in the formation of thiosemicarbazone comcom-pounds. The chemistry of the thiosemicarbazones has been drawing a lot of interest due to their potential donor atoms providing varied coor-dination modes [1e3]. The reason of the increasing of expectations from these kind compounds is that thiosemicarbazide-based ligand and metal complexes have many application possibilities such as medicine, analytic and organic processing due to their catalytic activities [4e6]. Additionally, the thiosemicarbazibased de-rivatives with an alkyl group on sulfur atom, S-alkyl thio-semicarbazones, are content of many studies investigating various biological activities such as antimicrobial, antiviral [7,8], cytotox-icity [9] and proliferation [10] features.
As reported, mixed-ligand complexes of thiosemicarbazones are functional in vital mechanisms like enzyme activation [11,12].
Phenanthroline groups [13], diamines [14], hydroxy compounds [15] and phosphines [16,17] are widely preferred co-ligands. In the last years, metal-thiosemicarbazone complexes bearing phosphine derivatives have considerable interest due to the catalyst features [18e20].
The aim of this study is to synthesize new acetophenone iso-thiosemicarbazide ligand and its nickel(II) complex and to exhibit experimental and theoretical structural analysis of the synthesized compounds (Fig. 1) and to have comparision of them. For this purpose, infrared, electronic,1H NMR, and X-ray spectroscopies were used in the experimental explanation of the structures. The electronic properties of the compounds were also obtained via quantum-mechanical calculations. Electrostatic potential (ESP) and the molecular electrostatic potential (MEP) analyses were per-formed to predict the nucleophilic and electrophilic reaction sites of the molecules. 2. Experimental 2.1. Synthesis Synthesis of 5-methyl-2-hydroxy-acetophenone-S-methyl-* Corresponding author. ** Corresponding author.
E-mail addresses:sguveli@istanbul.edu.tr(S¸. Güveli),ikilic@omu.edu.tr(I. Kılıç-Cıkla).
Contents lists available atScienceDirect
Journal of Molecular Structure
j o u r n a l h o me p a g e : h t t p : / / w w w . e l s e v i e r . c o m/ l o ca t e / m o l s t r u c
https://doi.org/10.1016/j.molstruc.2018.06.102
thiosemicarbazone (H2L).
The ligand was gained by using the literature method [21]. The compound was used after recrystallization from ethanol. Analytical and spectroscopic data of the yellow colored ligand is below.
H2L: m. p. 149e150C; yield 75%; Analytical data for C11H15N3OS
(237.32 g mol1): C, 55.67; H, 6.37; N, 17.71; S, 13.51. Found: C, 55.55; H, 6.26; N, 17.60; S, 13.45 (%). FT-IR (KBr, cm1):
n
(OH) 3170,n
as(NH2) 3368,n
s (NH2) 3312,d
(NH2) 1639,n
(C]N1) 1587,n
(C]N2)1559,
n
(CeO) 1309,n
(CeS) 692.1H NMR (CDCl3, 25C, ppm, J in Hz):13.04, 12.92 (cis/trans isomer: 1/1, s, 1H, OH), 7.24 (dd, J¼ 1.46, J¼ 11.22, 1H, d), 6.99 (dd, J ¼ 1.95, J ¼ 8.78, 1H, b), 6.80 (d, J ¼ 8.30, 1H, a), 4.86 (cis/trans isomer: 3/1, s, 2H, N3H2), 2.45, 2.40 (cis/trans
ratio 3/1, s, 3H, SeCH3), 2.24 (s, 3H, CeCH3).
2.1.1. Synthesis of nickel-PPh3complex
The solution of 2.37 g (1 mmol) of the ligand in 10 ml dichloromethane were mixed with 6.54 g (6, 1 mmol) of [Ni(PPh3)2Cl2] in 10 mL 2-propanol at room temperature and after
7 h, it was standed for about a week until the dark red product was obtained. The product was crystallized from n-hexan-dichloro-methane mixture (1:1). The characterization data of the nickel complex are below (p-t indicate PPh3protons).
[NiL (PPh3)] m. p. 198e199C; yield 77%; Anal. Calc. for
C29H28N3NiOPS (M 556.28 g mol1): C, 62.75; H, 5.15; N, 7.69; S, 5.92. Found: C, 62.61; H, 5.07; N, 7.55; S, 5.76%; FT-IR (KBr, cm1):
n
(C]N1) 1612,n
(C]N2) 1562,n
(PPh3) 1435, 1087, 700,n
(CeO) 1316,n
(CeS) 696;1H NMR (CDCl3, 25C, ppm, J in Hz): 7.77e7.58 (m, 6H, p, t), 7.49e7.46 (m, 3H, r), 7.41e7.39 (m, 6H, q, s), 7.38 (d, J ¼ 1.46, 1H, d),6.82 (s, 1H, b), 6.47 (d, J¼ 8.30, 1H, a), 5.22 (s, 1H, N3H), 2.94,2.21 (cis/trans ratio: 1/3, s, 3H, SeCH3), 2.02 (s, 3H, CeCH3).
2.2. Apparatus and methods
Infrared spectra of both compounds were obtained using a Bruker Vertex 80 V FTeIR spectrometer with KBr pellets. To record the electronic absorption spectra, Shimadzu 2600 UVeVisible Spectrometer was performed using 1.0 105M solutions of the
ligand and complex in methanol medium. The1H NMR spectra were obtained by a Bruker Avance/500 model spectrometer in chloroform, relative to SiMe4. Crystallographic measurements were
carried out on Bruker D8 QUEST and STOE IPDS II diffractometers using Mo/Ka radiation (
l
¼ 0.71073 Å) for ligand and complex, respectively. The structures were clarified by direct methods using SHELXS-2013 [22] and refined by a full matrix least squares pro-cedure using SHELXL-2014 [22]. While the hydrogen atoms on heteroatoms such as O and N were placed in a difference Fourier map and refined isotropically, the hydrogen atoms related to C atoms were positioned geometrically and refined utilizing a riding model. The final period of refinement process results thatR1¼ 0.0516, wR2¼ 0.1250 (H2L) and R1¼ 0.0497, wR2¼ 0.0573
[NiL(PPh3)] for the observed reflections. The information about the
crystal data and refinement parameters of the compounds is listed inTable 1.
2.3. Computational details
The first-hand geometries of the compounds were taken directly from the X/ray diffraction results and optimized consid-ering density functional theory (DFT) with the B3LYP [23,24] method. Except for the metal atom, the 6/311G (d,p) basis set [25,26] was applied to all atoms in the optimization process. The atom nickel has been symbolized by the quasi/relativistic LANL2DZ basis set [27]. All theoretical calculations in this work were evaluated using the Gaussian03W program package [28], performing the identical method and basis sets as used in the optimization process. The 1H chemical shifts were calculated within the GIAO approach [29,30] and converted to the TMS scale whose calculated absolute chemical shielding value of 31.97 ppm. The default model IEF/PCM [31] was preferred to include the ef-fect of the solvent on the theoretical NMR parameters using CDCl3.
The computed chemical shifts for hydrogen atoms of NH2and CH3
groups were given on average inTable 7. The harmonic vibrational frequencies were computed and scaled by 0.9679 [32] to confirm the calculated frequencies. We used the time-dependent density functional theory (TD/DFT) formalism [33e35] to calculate the electronic absorption spectra. The contour maps and MEP mapped surfaces of the compounds were taken using the same method. 3. Results and discussion
3.1. Crystallographic studies
The molecular structures of the ligand and complex are shown inFigs. 2e3and chosen geometrical parameters of the compounds recorded from X-ray analysis are listed inTable 2.
The S-methyl-thiosemicarbazone (1) crystallizes in the mono-clinic space group P 21/c with four molecules in the unit cell. The
molecule is in thiol tautomeric form with the cis (Z) configuration of the N1 atom according to the N3 atom. While the N1eC7 bond shows a strong double bond character, N2eC9 and N3eC9 bond lengths are between the single and double bond characters because of the
p
electron delocalization in the ligand. The thiol form of free ligand is supported by the CeS bond distance with a value of 1.765 (2) Å. The geometrical parameters of the ligand are consistent with the compounds reported in literature [36e38]. The thio-semicarbazone chain of the ligand (C7/N1/N2/C9/N3/S1) has a mean plane with small separation of 0.018 Å. The ligand is nearly planar with the dihedral angle of 5.31 (6)between the (C7/N1/N2/P
O
N
N
NH
S
Ni
C
H
3CH
3C
H
3[Ni(PPh
3)
2Cl
2]
-PPh
3- 2HCl
N
N
S
NH
2CH
3OH
C
H
3C
H
31
3
2
a
b
d
p
q
r
s
t
C9/N3/S1) plane and the phenyl ring. A hydrogen atom of the hy-droxyl group acts as bifurcated donor and creates two intra-molecular O1eH1/N1 and O1eH1/S1 hydrogen bonds, which form S (6) and S (5) ring motifs [39], respectively. The intermolec-ular hydrogen bonds causing the formation of the crystal packing of the ligand are presented inTable 3. N3eH3A$$$N2 hydrogen bond with details, which lie down along the b axis, forms R2
2ð8Þ [40]
centrosymmetric dimers as shown inFig. 4a. The atom O1 in the molecule at (-xþ1, y-1/2, -z þ 3/2) acts as hydrogen-bond acceptor to atoms N3 and C10 in main molecule and generates an infinite chain structure (Fig. 4b).
The complex, [NiL(PPh3)], is formed by the chelating of the
ligand on ONN coordination mode and the square planar geometry of the nickel (II) centered structure is complemented by the atom P of triphenylphosphine. The complex with eight molecules in the unit cell crystallizes in the orthorombic crystal system and space group P bca. The dihedral angle between the chelate rings formed with the coordination is 3.78 (5). There are no significant changes at angles of thiosemicarbazone moiety on coordination, phenolic C1eO1 bond length only shows a remarkable shortening from 1.353 (2) to 1.300 (6) Å. The coordination bond lengths well matched with the range of previously reported similar complexes [41e44]. The molecules are adjacent to each other with intermo-lecular CeH/N interactions to form a three dimensional network (Details are inTable 3) in the crystal structure of the complex. The mutual CeH/N interactions in the molecules at (x, y, z) and (-xþ1, -yþ1, -zþ1) forms the centrosymmetric dimers with R2
2ð10Þ motifs
(Fig. 5). The packing of the complex is supported by intermolecular CeH$$$
p
interactions.3.2. Optimized structures
The selected bond angles, torsion angles and bond lengths of the optimized structures are given inTable 2. As seen on the table, the geometrical parameters which came by single crystal X-ray analysis and by the DFT/B3LYP method revealed the acceptable
discrepancies. Because the intra and intermolecular forces are taken into account in the crystalline state, while the computational processes deal with isolated molecules [45]. The maximal differ-ences in the bond lengths and angles are around the atom N3 in the ligand and around the metal center in the complex. The structural accordance between the experimental and optimized geometries were quantitatively studied by the root mean square (r.m.s.) overlay for H2L and [NiL(PPh3)], the resulting RMSEs were 0.151 and 0.354,
respectively (Fig. 2).
The dihedral angles between the thiosemicarbazone chain (C7/ N1/N2/C9/S1/C10) and the phenyl ring (C1eC6) are 2.36 (X-ray) and 16.29 (DFT) for H2L and 4.44 (X-ray) and 1.33 (DFT) for
[NiL(PPh3)]. Comparing the X-ray structures with their optimized
counterparts, while the optimized geometry of the complex is more planar conformation than X-ray geometry, the planar conformation of the ligand is distorted in optimization.
3.3. Electrostatic potential (ESP) and molecular electrostatic potential (MEP) analyses
The MEP analysis is related to the electronic density and gives the knowledge regarding the reactive sites and hydrogen-bonding interactions of the molecules [46]. The contour maps are drawn in the molecular plain two dimensionally and used to show lines of constant density or brightness. In the MEPs, the maximum negative region, which is the favorable site for the electrophilic attack is indicated as a red color, the maximum positive region which preferred site for the nucleophilic attack is shown with blue color [47]. In the MEPs, potential decreases in order red> orange > yel-low> green > blue. ESP and MEP analyses of the optimized geom-etries were calculated at the B3LYP and demonstrated inFig. 6. The most negative atoms in the ligand are N1, N3 and O1 with the Mulliken charges of0.398, 0.386 and 0.337 a. u., respectively. The ligand coordinated to the positively charged metal through these atoms. The negative electrostatic potential region around oxygen in the MEP is theoretically potential active sides of the
Table 1
Crystal data and structure refinement parameters for H2L and [NiL(PPh3)].
H2L [NiL(PPh3)]
CCDC deposition number 1526251 1526252
Chemical formula C11H15N3OS C29H28N3NiOPS
Color/shape Yellow/Block Dark red/Prismatic plate
Formula weight 237.32 556.28
Crystal size (mm) 0.18 0.16 0.13 0.19 0.11 0.07 Wavelength (Å) MoKa,l¼ 0.71073 MoKa,l¼ 0.71073
Temperature (K) 296 296
Crystal system Monoclinic Orthorombic
Space group P 21/c P bca
Unit cell parameters
a, b, c (Å) 9.5912(6), 9.2441(6), 13.7120(8) 9.5787(4), 17.8104(8), 31.2400(18) a,b,g() 90, 92.933 (2), 90 90, 90, 90 Volume (Å3) 1214.14 (13) 5329.6 (4) Z 4 8 Density (Mgm3) 1.298 1.387 m(mm1) 0.250 0.894
Absorption correction Multi-scan Integration
Tmin, Tmax 0.675, 0.745 0.875, 0.969
F000 504 2320
qrange for data collection () 2.97q 28.30 1.30q 26.97
Index ranges 12 h 12, 12 k 12, 18 l 16 11 h 11, 21 k 21, 37 l 35 Reflections collected 44060 41162 Independent/observed reflections 3013/2328 4726/1936 Rint 0.044 0.184 Data/restraints/parameters 3013/0/158 4726/0/330 Goodness offit on F2 1.039 0.837
Final R indices [I> 2s(I)] 0.0516, 0.1250 0.0497, 0.0573
ligand and verify the intra and intermolecular hydrogen bonding of the molecule. The MEP of [NiL(PPh3)] shows that a maximum
negative regions are localized on nitrogen and sulfur atoms indi-cating a possible site for electrophilic attack. As a result, electro-negative atoms cause the formation of electro-negative potential sites while carbon and hydrogen atoms give the positive potential sites, as expected.
3.4. Electronic properties and UV spectra
The molecular orbital energies in the HOMO-10dLUMOþ5 range for nickel(II) complex are shown inTable 4. The contour plots of some chosen molecular orbitals are presented inFig. 7.
The high energy occupied orbitals of nickel(II) complex, the HOMO to HOMO-2 have mainly H2L (
p
) character withcontribu-tions of 95%, 80% and 80%, respectively, while HOMO-3 is concen-trated on Ni(d) orbitals (91%). The low lying unoccupied orbital, LUMO has the mixed contribution of PPh3(
p
*) and Ni(d) orbitals.Other low lying unoccupied orbitals, LUMOþ1, LUMOþ2 and LUMOþ4 have PPh3(
p
*) character. LUMOþ3 is mainly contributedby H2L (
p
*) (56%) and PPh3(p
*) (38%) orbitals.The UVeVisible spectra of both compounds taken in methanol
are given in Fig. 8. The spectrum of the ligand showed the
p
-p
* transitions belong to the aromatic rings at 221 nm and 292 nm. The n-p
* transitions related to the azomethine and thioamide groups were detected at 337 nm. The spectrum of the complex showed bands at 201, 296, 373 nm, which were assigned to the ligand transitions. The band at 337 nm in the spectrum of H2L shifts toabout 373 nm on complexation. To get a better understanding of electronic transitions, TD-DFT calculation on the optimized geom-etry of the complex was carried out. The vertical electronic exti-tations obtained with TD-DFT/PCM and the experimental equivalents are listed inTable 5.
The calculated maximum absorption wavelength belong to the electronic transition from the HOMO to LUMO with 46% contribu-tion and implies an electron density transfer. HOMO/LUMO transition has H2L (
p
)/PPh3(p
*) and H2L (p
)/Ni(d) character.The calculated strong transitions at 376 nm and 355 nm corre-sponding to HOMO/HOMO-1/LUMOþ1 have intra-ligand charge transfer [H2L (
p
)/ PPh3(p
*)] and comply with the experimentalband observed at 373 nm. 3.5. IR spectra
The noteworthy frequencies recorded in FT-IR spectrometer and calculated by B3LYP method, and probable assignments are listed in
Table 6. The experimental IR spectra are shown inFig. 9. Consid-ering systematic errors, we regulated the computed vibrational wavenumbers with scaling factor of 0.9679. Due to the crystal in-teractions (Van der Waals,
p
/p
stacking, hydrogen bonding etc.) in the solid phase, some frequencies which were calculated in gas phase can show small differences [48].It is stated that the nonhydrogen-bonded or a free hydroxyl group vibrations occur in the region of 3550e3700 cm1. Owing to the strong, sensitive of OH group vibrations to the environment, intramolecular hydrogen bonding would reduce the OeH stretch-ing band to the region of 3200e3550 cm1[49]. Because of intra-molecular hydrogen bonding formation of H2L, the OeH stretching
vibration was detected at 3170 cm1. Ligand was coordinated to nickel atom through an oxygen atom of phenolic OH, so this band disappeared in the spectrum of the complex. The NH stretching vibrations generally arise in the region of 3250e3500 cm1[50]. The NeH2symmetric and asymmetric stretching frequencies in the
spectrum of ligand were observed at 3312 cm1 and 3368 cm1, respectively. In the spectrum of complex, a new strong peak belonging to
n
(NeH) stretching vibration was observed at 3410 cm1, due to the coordination of the amino N atom. The spectral results indicate that the ligand is functional through ONN donor set of dibasic thiosemicarbazidato structure (L2).The IR spectra of the compounds exhibited very strong ab-sorptions at 1587 cm1, 1559 cm1 for ligand and at 1612 cm1, 1562 cm1for complex due to the azomethine
n
(C]N) groups. Then
(CeO) stretching band of the ligand shifted to higher frequency after the coordination to metal. Then
(CeH) aromatic stretching modes of the ligand and complex were observed at 3024 cm1and 3059 cm1, respectively. For CH3 groups, the CH asymmetricstretching vibrations generally are recorded at higher frequencies than those of the symmetric mode. In this study, the CH3symmetric
and asymmetric stretching frequencies were obtained at the pre-dicted region. The spectrum of complex includes also the charac-teristic bands of the coordinated PPh3ligand at ca. 1440, 1103, 745
and 700 cm1[42]. 3.6. NMR spectra
The 1H NMR chemical shifts recorded in chloroform and the calculated counterparts are given inTable 7.
Fig. 2. Experimental and optimized structures of H2L and atom-by-atom
The spectrum of ligand (H2L) shows two singlets at 12.92 and
13.04 ppm, which the integral values of the signals are equal to each other, attributed to one proton belonging to phenolic hydroxyl. Owing to the coordination of the deprotonated phenolate compo-nent, the hydroxyl proton signals disappeared in the spectrum of the complex. The signal assigned to NH2was observed at 4.86 ppm
as a singlet that equivalents to two protons. In the spectrum of the complex, one of the NH2protons has only been observed due to the
complex formation. After the formation of the ONN chelate, the N3 proton of the equivalent proton of the complex gives a significant shift to the lowerfield (from 4.86 to 5.20 ppm).
As known, the1H chemical shifts for hydrogen atoms in aro-matic rings give signals in the range of 6e8 ppm [16,43]. The pro-tons belong to the benzene rings (H2, H3 and H5) for studied compounds have signals in the range of 6.47e7.38 ppm. While the signals of protons H2 and H3 moved to the higherfield on the chelation, the proton H5 shifted to higher frequencies because of the proximity to thiosemicarbazone component. The signals related to the protons of the PPh3were obtained as multiplets in the range
of 7.39e7.77 ppm. The computed chemical shifts of both com-pounds are conformable with the experimental ones (Table 7).
Fig. 3. Experimental and optimized structures of [NiL(PPh3)] and atom-by-atom
su-perimposition of experimental (black) and optimized (red) structures.
Table 2
Some selected optimized and experimental parameters of H2L and [NiL(PPh3)].
Parameters H2L [NiL(PPh3)] XRD DFT XRD DFT Bond lengths (Å) Ni1eP1 e e 2.205 (2) 2.274 Ni1eO1 e e 1.815 (3) 1.831 Ni1eN1 e e 1.878 (4) 1.894 Ni1eN3 e e 1.829 (4) 1.856 S1eC9 1.765 (2) 1.789 1.757 (5) 1.786 O1eC1 1.353 (2) 1.342 1.300 (6) 1.313 N1eC7 1.291 (2) 1.300 1.300 (5) 1.314 N1eN2 1.396 (2) 1.378 1.406 (5) 1.386 N2eC9 1.306 (2) 1.288 1.305 (5) 1.308 N3eC9 1.339 (3) 1.378 1.341 (6) 1.336 Bond angles () N1eNi1eP1 e e 176.03 (15) 177.55 O1eNi1eN3 e e 177.37 (19) 178.14 N3eNi1eP1 e e 92.92 (15) 95.08 N1e Ni1eN3 e e 83.42 (19) 83.02 O1eNi1eP1 e e 88.49 (11) 86.66 O1eNi1eN1 e e 95.18 (17) 95.24 C7eN1eN2 118.10 (15) 117.45 117.3 (4) 117.91 C9eN2eN1 111.52 (16) 114.55 107.8 (4) 109.43 N2eC9eS1 120.59 (15) 122.59 113.7 (4) 113.62 N2eC9eN3 119.91 (18) 118.93 122.7 (5) 122.01 Torsion angles() C7eN1eN2eC9 178.9 (2) 168.7 174.9 (5) 177.2 N1eN2eC9eS1 1.8 (2) 6.0 178.6 (3) 174.9 N2eC9eS1eC10 168.6 (2) 167.6 170.9 (4) 162.4 N1eN2eC9eN3 176.5 (2) 171.5 1.0 (7) 4.2 Table 3
Hydrogen bonding geometries for H2L and [NiL(PPh3)].
D-H$$$A D-H H$$$A D$$$A D-H$$$A H2L O1/H1/N1 0.87 (3) 1.76 (3) 2.536 (2) 147
O1/H1/S1 0.87 (3) 2.55 (3) 3.2349 (17) 137 N3/H3A$$$N2i 0.88 (3) 2.31 (3) 3.179 (3) 172
N3/H3B/O1ii 0.84 (2) 2.24 (3) 3.025 (2) 158
C10/H10B/O1ii 0.96 2.40 3.299 (3) 157
[NiL(PPh3)] C8eH8B/N2iii 0.96 2.59 3.495 (7) 157
C3eH3$$$Cg1iv 0.93 2.90 3.745 (6) 151
D: donor; A: acceptor.
Symmetry codes: (i) -xþ1, y-1/2, -zþ3/2; (ii) -xþ1, -y, -zþ1; (iii) -xþ1, -yþ1, -zþ1; (iv) 1þ x, y, z [Cg1: C18eC23].
4. Conclusion
The new compounds, 5-methyl-2-hydroxy-S-methyl-acetophe-none thiosemicarbazone and its nickel-PPh3complex were
iden-tified by means of analytical, spectral, and X-ray crystallographic techniques The dibasic thiosemicarbazone (H2L) acts as tridentate
ligand, and this ONN-chelating structure, constitutes a square-planar geometry (ONNP) with the participation of PPh3. The
nickel(II) centered structure has a distortion with the value 3.78. The nickel(II) centered structure has a distorted square-planar ge-ometry with the value of four-coordinated gege-ometry index that is 0.05 [51].
DFT method was used to calculate the geometric parameters,
Fig. 4. (a) The crystal packing of H2L, viewed down b axis, with strong NeH/N
hydrogen bonds. (b) A partial view of the packing of H2L. Dashed lines represent
NeH/O (red) and CeH/O (green) hydrogen bonds.
Fig. 5. Part of the crystal structure of [NiL(PPh3)], showing the CeH/N hydrogen
bonds.
Fig. 6. Molecular electrostatic potential (MEP) and electrostatic potential (ESP) a) for H2L b) for [NiL(PPh3)].
Table 4
Energy and compositions of some selected MOs of [NiL(PPh3)].
MO E (eV) % of composition Ni H2L PPh3 LUMOþ5 0.63 16 9 75 LUMOþ4 0.96 1 2 97 LUMOþ3 1.04 6 56 38 LUMOþ2 1.17 3 18 79 LUMOþ1 1.27 8 22 70 LUMO 1.46 29 17 54 HOMO 4.95 4 95 1 HOMO-1 5.28 20 80 0 HOMO-2 6.15 20 80 0 HOMO-3 6.16 91 8 1 HOMO-4 6.56 9 58 33 HOMO-5 6.62 45 53 2 HOMO-6 6.94 44 54 2 HOMO-7 7.15 35 55 9 HOMO-8 7.21 10 16 75 HOMO-9 7.25 24 37 40 HOMO-10 7.31 4 8 88
chemical shifts of the1H NMR and vibrational frequencies of the compounds. The experimental data were evaluated by comparing the results of DFT method. With the thought that it may be a model for examining the biological activity and catalytic proper-ties of similar molecules, the nucleophilic and electrophilic sites of the molecules were calculated to determine the probable reaction sites.
The electronic absorption wavelengths and the energies of the effective molecular orbitals of the considered molecules are also investigated. As a conclusion, the DFT method was used to
reproduced from the X-ray crystallographic results. TD-DFT calcu-lations were also carried out and probable electronic transitions were utilized to specify the bands revealed in electronic spectra.
Acknowledgements
The authors acknowledge the Scientific and Technological Research Application and Research Center of Sinop University
Fig. 8. UV spectra of H2L (blue) and [NiL(PPh3)] (red) in MeOH.
Table 5
Vertical electronic extitations for [NiL(PPh3)] with TD-DFT/PCM.
Eexc.(eV) TDDFTl(nm) Osc. Strength (f) Key Transitions Character Exp.l(nm)
3.05 406 0.0052 (%46) H/L H2L (p)/ PPh3(p*)/Ni(d) 3.29 376 0.2838 (%73) H/L þ1 H2L (p)/ PPh3(p*) 373 3.49 355 0.2041 (%61) H-1/L þ1 H2L (p)/ PPh3(p*) 3.66 338 0.0055 (%97) H/Lþ2 H2L (p)/ PPh3(p*) 296 3.81 325 0.0126 (%97) H/Lþ3 H2L (p)/ H2L (p*)/PPh3(p*) 201 Table 6
The experimental and calculated vibrational frequencies (cm1) of H2L and
[NiL(PPh3)].
Assignmentsa H
2L [NiL(PPh3)]
Exp. (KBr) Calc. B3LYP Exp. (KBr) Calc. B3LYP
nOeH 3170 3150 e e nasNeH2 3368 3536 e e nsNeH2 3312 3429 e e nNeH e e 3410 3495 nsCeH 3024 3084 3059 3043 nasCeH3 2968 3021 2920 3018 nsCeH3 2920 2944 2855 2941 aNeH2 1639 1603 e e nC]N1 1587 1578 1612 1548 nC]N2 1559 1557 1562 1515 gNeH e e 1510 1343 aCeH3 1479 1449 1435 1439 nCeO 1309 1287 1316 1305 nCeS 692 683 696 686
Assignmentsa:n, stretching;a, scissoringg, rocking.
Abbreviations: s, symmetric; as, asymmetric.
Fig. 9. Experimental IR spectra belong to compounds.
Table 7
Experimental and calculated1H NMR chemical shiftsd(ppm) from TMS for the
compounds. H2L [NiL(PPh3)] CDCl3 B3LYP CDCl3 B3LYP H1(OH) 12.92(s)/13.04(s) 12.29 e e H1 (NH) e e 5.22(s) 5.26 H2 6.80 (d) 7.03 6.47 (d) 6.64 H3 6.99 (t) 7.35 6.82 (d) 7.04 H3 (NH2) 4.86 (s) 3.79a e e H5 7.24 (dd) 7.42 7.38 (t) 7.62 H8 (CH3) 2.45 (s) 2.51a 2.21(s) 3.02a H10 (CH3) 2.40 (s) 2.35a 2.94(s) 1.67a H11 (CH3) 2.24(s) 2.30a 2.02(s) 2.26a H13 e e 7.77e7.58 (m) 7.67 H14 e e 7.41e7.39 (m) 7.65 H15 e e 7.49e7.46 (m) 7.65 H16 e e 7.41e7.39 (m) 7.53 H17 e e 7.77e7.58 (m) 7.04 H19 e e 7.77e7.58 (m) 7.51 H20 e e 7.41e7.39 (m) 7.67 H21 e e 7.49e7.46 (m) 7.74 H22 e e 7.41e7.39 (m) 7.69 H23 e e 7.77e7.58 (m) 9.17 H25 e e 7.77e7.58 (m) 7.53 H26 e e 7.41e7.39 (m) 7.63 H27 e e 7.49e7.46 (m) 7.76 H28 e e 7.41e7.39 (m) 7.77 H29 e e 7.77e7.58 (m) 9.45 a: average.
(Turkey) for the use of the Bruker D8 QUEST diffractometer. The authors sincerely thank Ondokuz Mayıs University (Turkey) for providing analysis using the STOE IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund). This work was also supported by the BAP (The Scientific Research Projects Coor-dination Unit of Istanbul University (Turkey), Project Numbers: 23552).
Appendix A. Supplementary data
Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Center, CCDC reference number: 1526251 (H2L) and 1526252 [NiL (PPh3)]. Copies
of this information may be obtained free of the charge from the Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (Fax: þ44-1223-336033; E-mail:deposit@ccdc.cam.ac.ukorhttp://www.ccd. cam.ac.uk).
References
[1] Z.G. Jiang, M.S. Lebowitz, H.A. Ghanbari, Neuroprotective activity of 3-aminopyridine-2-carboxaldehydethiosemicarbazone (PAN-811), a cancer therapeutic agent, CNS Drug Rev. 12 (2006) 77e90.
[2] H. Beraldo, D. Gambino, The wide pharmacological versatility of semi-carbazones, thiosemicarbazones and their metal complexes, Mini Rev. Med. Chem. 4 (2004) 31e39.
[3] Y.D. Kurt, B. _Ilhan-Ceylan, M. Açıkg€oz, E. Tüzün, G. Atun, B. Ulkuseven, N2O2
-complexes of oxovanadium(IV) with 2,20-dihydroxybenzophenone
thio-semicarbazones: synthesis, EPR and electrochemical studies, Polyhedron 65 (2013) 67e72.
[4] S.N. Youssef, A.M.A. El-Seidy, M. Schiavoni, B. Castano, F. Ragaini, E. Gallo, A. Caselli, Thiosemicarbazone copper complexes as competent catalysts for olefin Cyclopropanations, J. Organomet. Chem. 714 (2012) 94e103. [5] T. Bal Demirci, G. Congur, A. Erdem, S. Erdem-Kuruca, N. €Ozdemir, K.
Akgun-Dar, et al., Iron(III) and nickel(II) complexes as potential anticancer agents: synthesis, physicochemical and structural properties, cytotoxic activity and DNA interactions, New J. Chem. 39 (2015) 5643e5653.
[6] Z. Afrasiabi, E. Sinn, W. Lin, Y. Ma, C. Campana, S. Padhye, Nickel (II) complexes of naphthaquinone thiosemicarbazone and semicarbazone: synthesis, struc-ture, spectroscopy, and biological activity, J. Inorg. Biochem. 99 (2005) 1526e1531.
[7] A. Kolocouris, K. Dimas, C. Pannecouque, M. Witvrouw, G.B. Foscolos, G. Stamatiou, et al., New 2-(1-adamantylcarbonyl)pyridine and 1-acetyladamantane thiosemicarbazones-thiocarbonohydrazones: cell growth inhibitory, antiviral and antimicrobialactivity evaluation, Bioorg. Med. Chem. Lett 12 (2002) 723e727.
[8] S¸. Güveli, K. Turan, B. Ülküseven, Nickel(II)-PPh3complexes with ONS and
ONN chelating thiosemicarbazones: synthesis and inhibition potential on influenza A viruses Turk, J. Chem. 42 (2018) 371e384.
[9] B. Atasever, B. Ülküseven, T. Bal-Demirci, S. Erdem-Kurucaand, Z. Solakoglu,
Cytotoxic activities of new iron(iii) and nickel(ii) chelates of some S-Methyl-Thiosemicarbazones on K562 and Ecv304 cells, Invest. N. Drugs 28 (2010) 421e432.
[10] R. Yanardag, T. Bal Demirci, B. Ülküseven, S. Bolkent, S. Tunalı, S. Bolkent, Synthesis, characterization and antidiabetic properties of N1-2,4-
Dihydroxybenzylidene-N4-2-Hydroxybenzylidene-S-Methyl-Thio-semicarbazidato-Oxo vanadium(iv), Eur. J. Med. Chem. 44 (2009) 818e826. [11] R. Sharma, M. Nagar, M. Agarwal, H. Sharma, Synthesis, characterization and
antimicrobial activities of some mixed ligand complexes of Co(II) with thio-semicarbazones and N-protected amino acids, J. Enzym. Inhib. Med. Chem. 24 (2009) 197e204.
[12] A.C. Ekennia, D.C. Onwudiwe, L.O. Olasunkanmi, A.A. Osowole, E.E. Ebenso, Mixed ligand complexes of N-Methyl-N-phenyl dithiocarbamate: synthesis, characterisation, antifungal, activity, and solvent extraction studies of the ligand, Bioinorgan. Chem. Appl. 2015 (2015) 1e12.
[13] T.S. Lobana, S. Indoria, H. Sood, D.S. Arora, S.B. Randhawa, I. Garcia-Santos, V.A. Smolinski, J.P. Jasinski, Synthesis of 5-nitro-salicylaldehyde-N-substituted thiosemicarbazonates of copper(II): molecular structures, spectroscopy, ESI-mass studies and antimicrobial activity, Inorg. Chim. Acta. 461 (2017) 248e260.
[14] T. Bal Demirci, Synthesis, spectroscopic and crystallographic characterization of the cobalt(III) ternary mixed-ligand complexes of N(4)-allyl/methyl thio-semicarbazones, N, N,N',N'-tetramethylethylenediamine and azide, Poly-hedron 27 (2008) 440e446.
[15] S. Eglence, M. Sahin, M. Ozyurek, R. Apak, B. Ulkuseven, Dioxomolybde-num(VI) complexes of S-methyl-5-bromosalicylidene-N-alkyl substituted thiosemicarbazones: synthesis, catalase inhibition and antioxidant activities, Inorg. Chim. Acta. 469 (2018) 495e502.
[16] S¸. Güveli, T. Bal Demirci, N. €Ozdemir, B. Ülküseven, Nickel(II) complexes of
ONS and ONN chelating thiosemicarbazones with triphenylphosphine co-li-gands, Transit. Met. Chem. 34 (2009) 383e388.
[17] M. Shabbir, Z. Akhter, A.R. Ashraf, H. Ismail, A. Habib, B. Mirza, Nickel(II) and palladium(II) triphenylphosphine complexes incorporating tridentate Schiff base ligands: synthesis, characterization and biocidal activities, J. Mol. Struct. 1149 (2017) 720e726.
[18] G. Erre, S. Enthaler, K. Junge, S. Gladiali, M. Beller, Synthesis and application of chiral monodentate phosphines in asymmetric hydrogenation, Coord. Chem. Rev. 252 (2008) 471e491.
[19] S. Guveli, S. Cinar-Agopcan, O. Karahan, V. Aviyente, B. Ulkuseven, Nickel(II)e PPh3complexes of S,N-Substituted thiosemicarbazones-structure, DFT study,
and catalytic efficiency, Eur. J. Inorg. Chem. 2016 (2016) 538e544. [20] S. Priyarega, P. Kalaivani, R. Prabhakaran, T. Hashimoto, A. Endo, K. Natarajan,
Nickel(II) complexes containing thiosemicarbazone and triphenylphosphine: synthesis, spectroscopy, crystallography and catalytic activity, J. Mol. Struct. 1002 (2011) 58e62.
[21] C. Yamazaki, The structure of isothiosemicarbazones, Can. J. Chem. 53 (1975) 610e615.
[22] G.M. Sheldrick, A short history of SHELX, Acta Crystallogr. A 64 (2008) 112e122.
[23] C. Lee, W. Yang, R.G. Parr, Development of the Colle-Salvetti correlation-en-ergy formula into a functional of the electron density, Phys. Rev. B 37 (1988) 785e789.
[24] A.D. Becke, Density-functional thermochemistry. III. The role of exact ex-change, J. Chem. Phys. 98 (1993) 5648e5652.
[25] A.D. McLean, G.S. Chandler, Contracted Gaussian basis sets for molecular calculations. I. Second row atoms, Z¼11e18, J. Chem. Phys. 72 (1980) 5639e5648.
[26] K. Raghavachari, J.S. Binkley, R. Seeger, J.A. Pople, Self-consistent molecular orbital methods. XX. A basis set for correlated wave functions, J. Chem. Phys. 72 (1980) 650e654.
[27] P.J. Hay, W.R. Wadt, Ab initio effective core potentials for molecular calcula-tions. Potentials for the transition metal atoms Sc to Hg, J. Chem. Phys. 82 (1985) 270e310.
[28] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A. Pople, Gaussian 03, Revision E.01, Gaussian Inc., Wallingford, CT, 2004.
[29] R. Ditchfield, Molecular orbital theory of magnetic shielding and magnetic susceptibility, J. Chem. Phys. 56 (1972) 5688e5691.
[30] K. Wolinski, J.F. Hinton, P. Pulay, Efficient implementation of the gauge-independent atomic orbital method for NMR chemical shift calculations, J. Am. Chem. Soc. 112 (1990) 8251e8260.
[31] E. Cances, B. Mennucci, J. Tomasi, A new integral equation formalism for the polarizable continuum model: theoretical background and applications to isotropic and anisotropic dielectrics, J. Chem. Phys. 107 (1997) 3032e3041. [32] M.P. Andersson, P. Uvdal, New scale factors for harmonic vibrational
fre-quencies using the B3LYP density functional method with the triple-zbasis set 6-311þG(d, p), J. Phys. Chem. 109 (2005) 2937e2941.
[33] R. Bauernschmitt, R. Ahlrichs, Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory, Chem. Phys. Lett. 256 (1996) 454e464.
[34] R.E. Stratmann, G.E. Scuseria, M.J. Frisch, An efficient implementation of time-dependent density-functional theory for the calculation of excitation energies of large molecules, J. Chem. Phys. 109 (1998) 8218e8224.
[35] M.E. Casida, C. Jamorski, K.C. Casida, D.R. Salahub, Molecular excitation en-ergies to high-lying bound states from time-dependent density-functio-nal response theory: characterization and correction of the time-dependent local density approximation ionization threshold, J. Chem. Phys. 108 (1998) 4439e4449.
[36] R. Takjoo, A. Akbari, M. Ahmadi, H.A. Rudbari, G. Bruno, Synthesis, spectros-copy, DFT and crystal structure investigations of 3-methoxy-2-hydroxybenzaldehyde S-ethylisothiosemicarbazone and its Ni(II) and Mo(VI) complexes, Polyhedron 55 (2013) 225e232.
[37] G. Argay, A. Kalman, B. Ribar, V.M. Leovac, A.F. Petrovic, Synthesis and mo-lecular structure of salicylaldehyde S-methyl-isothiosemicarbazone, Monatsh. Chem. 114 (1983) 1205e1211.
[38] M. Ahmadi, A. Fasihizad, B. Machura, R. Kruszynski, T. Barak, New complexes of an unsymmetrical tetradentate isothiosemicarbazone: structural, spectral and thermogravimetric investigations, and their nanoparticles synthesis, Polyhedron 81 (2014) 115e122.
[39] J. Bernstein, R.E. Davis, L. Shimoni, N.L. Chang, Patterns in hydrogen bonding: functionality and graph set analysis in crystals, Angew Chem. Int. Ed. Engl. 34 (1995) 1555e1573.
[40] K. Balasubramani, P.T. Muthiah, D.E. Lynch, R22(8) motifs in Aminopyrimidine
sulfonate/carboxylate interactions: crystal structures of pyrimethaminium benzenesulfonate monohydrate (2:2:1) and 2-amino-4,6-dimethylpyrimidinium sulfosalicylate dihydrate (4:2:2), Chem. Cent. J. 1 (2007) 1e10.
[41] P. Kalavani, S. Saranya, P. Poornima, R. Prabhakaran, F. Dallemer, V. Vijaya Padma, K. Natarajan, Biological evaluation of new nickel(II) metallates: syn-thesis, DNA/protein binding and mitochondrial mediated apoptosis in human lung cancer cells (A549) via ROS hypergeneration and depletion of cellular antioxidant pool, Eur. J. Med. Chem. 82 (2014) 584e599.
[42] M.M. Tamizh, K. Mereiter, K. Kirchner, B.R. Bhat, R. Karvembu, Synthesis, crystal structures and spectral studies of square planar nickel (II) complexes containing an ONS donor Schiff base and triphenylphosphine, Polyhedron 28 (2009) 2157e2164.
[43] S¸. Güveli, N. €Ozdemir, T. Bal-Demirci, B. Ülküseven, M. Dinçer, €O. Andaç, Quantum-chemical, spectroscopic and x-ray diffraction studies on nickel complex of 2-hydroxyacetophenone thiosemicarbazone with triphenylpho-spine, Polyhedron 29 (2010) 2393e4303.
[44] I. Kılıç-Cıkla, S¸. Güveli, T. Bal-Demirci, M. Aygün, B. Ülküseven, M. Yavuz, X-ray diffraction, spectroscopic and DFT studies on nickel(II)- triphenylphosphine complexes of 2-hydroxyacetophenone thiosemicarbazones, Polyhedron 130 (2017) 1e12.
[45] G. €O. Tarı, Ü. Ceylan, E. Agar, H. Eserci, Crystal structure, spectroscopic in-vestigations and quantum chemical computational study of
5-(diethylamino)-2-((3-nitrophenylimino) methyl) phenol, J. Mol. Struct. 1126 (2016) 83e93. [46] H. Tanak, F. Koçak, E. Agar, A combined experimental (XRD, FT-IR, and
UVeVis) and DFT computational studies on (E)-N-[4-bromo-2-(tri-fluromethoxy)phenyl]-1-(5-nitrothiophen-2-yl)methanimine, Mol. Phys. 114 (2016) 197e212.
[47] R.J. Xavier, P. Dinesh, Vibrational spectra, monomer, dimer, NBO, HOMO, LUMO and NMR analyses of trans-4-hydroxy-I-proline, Spectrochim. Acta, Part A 128 (2014) 54e68.
[48] H. Saral, €O. €Ozdamar, _I. Uçar, Y. Bekdemir, M. Aygün, Synthesis, spectroscopic characterization and DFT calculations of N-Methyl-2-(2-hydoxyphenyl)benz-imidazole derivatives, J. Mol. Struct. 1103 (2016) 9e19.
[49] H. Tanak, A. Alaman Agar, O. Buyukgungor, Quantum-chemical, spectroscopic and X-ray diffraction studies of (E)-2-[(2-Bromophenyl)iminomethyl]-4-trifluoromethoxyphenol, Spectrochim. Acta Mol. Biomol. Spectrosc. 87 (2012) 15e24.
[50] Y. Bing€ol Alpaslan, H. G€okçe, M. Macit, G. Alpaslan, N. €Ozdemir, Molecular
structure, spectroscopic characterization and DFT calculations of a novel (Z)-1-[(2-Ethylphenylamino)methylene]naphthalene-2(1H)-one, J. Mol. Struct. 1096 (2015) 43e54.
[51] L. Yang, D.R. Powell, R.P. Houser, Structural variation in copper(I) complexes with pyridylmethylamide ligands: structural analysis with a new four-coordinate geometry index,t4, Dalton Trans. (2007) 955e964.
