Synthesis and crystal structures of the five-coordinate diorganotin(IV) complex [Ph2Sn(L)]·DMF and its 5-hydroxypyrazoline ligand (H2L)

Article abstract of DOI:10.1007/s10870-010-9914-4

A five-coordinate diorganotin(IV) complex [Ph₂Sn(L)]·DMF and its ligand, 5-hydroxy-3-methyl-5-phenyl-(N₄- phenylthiosemicarbazone)pyrazoline (H₂L), were synthesized and characterized by elemental analysis, IR, NMR (1H, 13C) spectroscopies and X-ray crystallography techniques. Our studies revealed that H₂L has formed as 5-hydroxy-4,5-dihydropyrazoline derivative in orthorhombic, Pbca space group with a = 15.4330(3) A, b = 11.5427(2) A, c = 18.1440(3) Awhereas [Ph₂Sn(L)]·DMF crystallizes with two independent molecules (a and b) in the asymmetric unit in triclinic system, P space group with a = 9.2795(1) A , b = 15.8315(2) A, c = 19.9895(3) A, α = 100.855(1)°,β = 92.985(1)°, γ = 102.243(1)°. In molecule a, the central Sn(IV) atom adopts a distorted tetragonal-pyramidal (TTP) geometry with N2 atom at apical position, while in molecule b the Sn(IV) occupies the centre of a trigonal-bipyramid (TBP) with N2 atom of the ONS-tridentate ligand and both Ph groups occupying equatorial positions. One molecule of DMF (crystallization solvent) helps in stabilizing the crystal structure. Springer Science+Business Media, LLC 2010.

Full text of DOI:10.1007/s10870-010-9914-4

J Chem Crystallogr (2011) 41:528–532
DOI 10.1007/s10870-010-9914-4
ORIGINAL PAPER
Synthesis and Crystal Structures of the Five-Coordinate
Diorganotin(IV) Complex [Ph2Sn(L)]ÁDMF
and its 5-Hydroxypyrazoline Ligand (H2L)
•
Gerimario F. de Sousa Daniel R. Marques
•
´
Ines S. Resck Jose R. Sabino
•
ˆ
´
Received: 17 June 2010 / Accepted: 17 November 2010 / Published online: 9 December 2010
Ó Springer Science+Business Media, LLC 2010
Abstract A five-coordinate diorganotin(IV) complex
[Ph2Sn(L)]ÁDMF and its ligand, 5-hydroxy-3-methyl-5-phe-
nyl-(N4-phenylthiosemicarbazone)pyrazoline (H2L), were
synthesized and characterized by elemental analysis, IR,
NMR (1H, 13C) spectroscopies and X-ray crystallography
techniques. Our studies revealed that H2L has formed as
5-hydroxy-4,5-dihydropyrazoline derivative in orthorhombic,
Introduction
NNO–, ONO– and specially ONS-tridentate hydrazones
synthesized from 2-acetylpyridine, 2-hydroxyacetophe-
none and salicylaldehyde are among the most extensively
investigated chelating agents over the past several years
[1–5]. These thio- and semicarbazones chelating com-
pounds are of considerable interest, because of their phar-
macological applications and ability to form interesting
chelates with transition metals, which in some cases possess
enhanced biological activity, such as antitumor, antibacte-
rial, antiviral and antimalarial activities [4–8]. Recently,
the ONO-coordination behavior of 4-phenyl-2-4-butane-
dione-benzoylhydrazone (5-dihydropyrazoline derivative)
towards diorganotin(IV) derivatives has been reported
[4]. However, diorganotin(IV) complexes prepared from
5-hydroxypyrazoline derivatives with ONS-donor capacity,
have been much less studied [9, 10]. In view of this, we are
reporting the synthesis and characterization of a new five-
coordinated diorganotin(IV) complex containing the ligand
shown in Scheme 1. As far as we know, the ligand (H2L)
was prepared for the first time and [Ph2Sn(L)]ÁDMF is the
first complex synthesized from 5-hydroxy-4,5-dihydropy-
razoline thiohydrazone which has been characterized by
X-ray crystallography.
˚
Pbca space group with a = 15.4330(3) A, b = 11.5427(2) A,
˚
˚
c = 18.1440(3) A whereas [Ph2Sn(L)]ÁDMF crystallizes
with two independent molecules (a and b) in the asymmetric
unit in triclinic system, P¯ı space group with a = 9.2795(1)
˚
˚
˚
A, b = 15.8315(2) A, c = 19.9895(3) A, a = 100.855(1)°,
b = 92.985(1)°, c = 102.243(1)°. In molecule a, the central
Sn(IV) atom adopts a distorted tetragonal–pyramidal (TTP)
geometry with N2 atom at apical position, while in molecule
b the Sn(IV) occupies the centre of a trigonal-bipyramid
(TBP) with N2 atom of the ONS-tridentate ligand and both
Ph groups occupying equatorial positions. One molecule of
DMF (crystallization solvent) helps in stabilizing the crystal
structure.
Keywords Diorganotin(IV) complex Á Pyrazoline
derivative Á Crystal structures
Experimental
G. F. de Sousa (&) Á D. R. Marques Á I. S. Resck
Physical Measurements
´ ´
Instituto de Quımica, Universidade de Brasılia,
´
70919-970 Brasılia, DF, Brazil
e-mail: gfreitas@unb.br
Elemental analyses were performed using a FISSONS
CHNS, mod. EA 108 microanalizer. Infrared spectra were
recorded on a BOMEM MB100 FT-IR spectrophotome-
ter in the 4000–400 cm-1 range using KBr pellets. NMR
J. R. Sabino
Instituto de Fısica, Universidade Federal de Goias,
´
74001-970 Goiania, GO, Brazil
´
ˆ
123

J Chem Crystallogr (2011) 41:528–532
529
–CH3); 2.89 (d, 6H, J 45.0 Hz; –N(CH3)2); 5.81 (s, 1H,
–CH). 13C NMR (75.46 MHz, CDCl3): d 26.5 (1C); 162.5
(2C); 94.7 (3C); 162.5 (4C); 137.8 (5C); 169.9 (11C); 135.7
(12C). IR (KBr), m(cm-1): m(N–H): 3281 m; m(C=O, DMF):
1653 s; m(C=N): 1561 s, 1519 s; m(C=C): 1487 s, 1452 s,
1429 m; m(N–N): 1019 m; m(C=S): 770 w; m(Sn–O): 527 w.
CH3
N
N
C
HO
S
N
H
Crystal Structure Determinations and Refinements
X-ray crystallography analysis were carried out using a
KappaCCD diffractometer [11] using graphite-monochro-
Scheme 1 The molecular structure of H2L
˚
mated Mo Ka (k = 0.71073 A) radiation at room temper-
ature. Colorless and orange block crystals of the ligand and
of the complex were mounted on glass fibers with glue.
Diffraction data were collected up to h = 27.5° from both
crystals and the data reductions were performed with Denzo
[12]. The X-ray crystal structures were solved by the heavy
atom method and Direct Methods with SHELXS-97 [13],
and refined with anisotropic atomic displacement by full
matrix least-squares on F2 using SHELXL-97 [13].
Hydrogen atom positions were calculated at idealized
positions and refined isotropic using the riding model con-
straints to their parent atoms. The complex phenyl rings
were refined as rigid groups with fixed C–C bond lengths of
spectra were recorded on a VARIAN MERCURY PLUS
1
spectrometer (7.05 T) operating at 300 MHz for H and at
75.46 MHz for 13C.
Synthesis
All chemical were of reagent grade and were used without
further purification. N4-phenylthiosemicarbazide was pre-
pared from phenyl isothiocyanate and hydrazine monohy-
drate in an anhydrous mixture of ethanol/ether (1:1) with
stirring [10]. The 5-hydroxy-3-methyl-5-phenyl-(N4-phe-
nylthiosemicarbazone)pyrazoline ligand (H2L) was syn-
thesized by refluxing a 1:1 M ratio mixture of benzoyl
acetone and the semicarbazide in methanol. Cooling fol-
lowed by slow evaporation of the solvent produced single
crystals for X-ray study. Its structure is shown in Scheme 1.
H2L: Anal. Calcd for C17H17N3OS (311.40 g/mol): C
65.57, H 5.50, N 13.49, S 10.30%; Found: C 64.93, H 5.21,
N 13.38, S 10.23%, color: yellow, yield: 78%, m.p.:
139–140 °C. 1H NMR (300 MHz, CDCl3): d 2.11 (t, J 0.98;
3H, –CH3); 3.07 (d, J 0.96; 1Ha, –CHaHb); 3.47 (d, J 1.06;
1Hb, –CHaHb); 9.15 (s, 1H, –NH). 13C NMR (75.46 MHz,
CDCl3): d 16.44 (1C), 154.9 (2C), 55.5 (3C), 95.7 (4C);
144.6 (5C); 173.4 (12C); 138.0 (10C). IR (KBr), m(cm-1):
m(O–H): 3459 vs; m(N–H): 3337 vs; m m(C=N–N=C): 1590
vs; m(C=C): 1516 s, 1451 s, 1410 s; m(N–N): 959 m;
m(C=S): 858 m.
˚
1.39 A. Further details of the structure analysis for the
ligand and complex are summarized in Table 1.
Results and Discussion
Crystal Structure of H2L
The ORTEP plot of H2L is shown in Fig. 1 along with the
atom numbering scheme. Selected bond lengths and angles
with their estimated standard deviations are compiled in
Table 2. The structure obtained confirms the cyclization
reaction and the formation of the 5-hydroxy-4,5-dihydro-
pyrazoline derivative. The compound crystallizes in the
centrosymmetric space group Pbca and exhibits two intra-
molecular hydrogen bonds of type O1–H1ÁÁÁS1, with
˚
The complex [Ph2Sn(L)]ÁDMF was obtained by a gen-
eral method. 0.27 g (0.87 mmol) of H2L was dissolved in
10 ml of CHCl3. To this solution were added three drops of
Et3N, followed by the slow addition of 0.30 g (0.87 mmol)
Ph2SnCl2 dissolved in 10 ml of MeOH. The mixture was
stirred at room temperature for 24 h, and the yellow
product was filtered, washed with hexane and dried in air.
Orange single crystals suitable for X-ray crystallography
were obtained by recrystallization from DMF. [Ph2Sn(L)]Á
DMF: Anal. Calcd for C61H57N7O3S2Sn2 (1237.64 g/mol):
C 59.20, H 4.64, N 7.92, S 5.18% Found: C 58.87, H 4.56,
N 7.85, S 5.12%, color: yellow, yield: 67%, m.p.:
distance 3.107(2) A and angle 137° forming a pseudo six-
membered ring, and of type N3–H3ÁÁÁN2 with distance
2.612(2) and angle 108.9° forming a pseudo five-membered
ring, which help in stabilizing the structure. The
˚
N2–C2 = 1.280(3) A double bond length and the C2–C3 =
1.483(3), C3–C4 = 1.536(3), C4–N1 = 1.490(3) and
˚
N1–N2 = 1.406(3) A single bond lengths are very close to
those found in a similar pyrazoline derivative [4]. The
C11–S1 = 1.6770(19) bond length indicates double-bond
nature. As expected, the bond angles of O1–C4–C5 =
112.57(16), C3–C4–N1 = 100.39(15), O1–C4–C3 =
108.34(16) and C5–C4–N1 = 110.91(16)° indicate that the
C4 asymmetric center is sp3 hybridized.
1
160–162 °C. H NMR (300 MHz, CDCl3): d 2.45 (s, 3H,
123

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J Chem Crystallogr (2011) 41:528–532
Table 1 Crystal data and structure refinement for H2L and
[Ph2Sn(L)]ÁDMF
C8
C5
C7
C9
C3
C6
C1
Identification code
Empirical formula
Formula weight
H2L
[Ph2Sn(L)]ÁDMF
C61H57N7O3S2Sn2
1237.64
C2
C10
C17H17N3OS
311.41
C4
(g mol-1
)
O1
N2
Temperature (K)
Crystal system
Space group
Color
298(2)
298(2)
Triclinic
P¯ı
Orthorhombic
Pbca
N1
Colourless
Orange
C11
S1
Crystal size (mm)
0.10 9 0.12 9 0.25 0.10 9 0.16 9 0.19
˚
a (A)
N3
15.4330(3)
11.5427(2)
18.1440(3)
9.2795(1)
15.8315(2)
19.9895(3)
100.855(1)
92.985(1)
102.243(1)
2805.50(6)
1256
˚
b (A)
C12
˚
c (A)
C13
C14
a (°)
b (°)
c (°)
C17
3
˚
Volume (A )
3232.15(10)
1312
C16
C15
F (000)
Z
8
2
Fig. 1 ORTEP plot of H2L with the displacement parameters drawn
at the 30% probability level. The dashed lines indicate intramolecular
hydrogen bonding
Calculated density
1.280
0.205
1.465
Absorption Coefficient
(mm-1
1.016
)
Limiting indices
–20 B h B 16
–14 B k B 12
–23 B l B 23
26233
–12 B h B 11
–20 B k B 20
–25 B l B 25
87760
collaborators [15] are 0.49 for molecule a and 0.61 for
molecule b. Thus for molecule a, tetragonal-pyramidal
(TTP) geometry predominates over trigonal-bipyramidal
(TBP) for molecule b. This might be explained by the steric
repulsion out of the phenyl ring C12a/C17a of the neighbor
molecule, which interacts with the phenyl rings C20b/C25b
and C30b/C35b upon the crystal packing (see Fig. 3).
Besides, the complex presents two intermolecular hydro-
Reflections collected
Reflections observed
[I [ 2r(I)]
Absorption correction
3692
12850
None
Gaussian [14]
0.9052/0.8303
Max. and min.
transmission
Data/parameters
Goodness-of-fit on F2
3692/201
1.040
12850/584
1.006
˚
gen bonds of types N3a–HÁÁÁO2 = 2.951(5) A and
N3b–HÁÁÁO2i = 3.030(5) (i: 1 ? x, y, 1 ? z), which con-
nect the molecules a and b to the DMF solvate (see Fig. 3).
As in other complexes [2, 3] containing ONS-tridentate
thiosemicarbazones, the main distortion from regular
geometry comes from the stereochemical constraints
imposed by the ligand, which reduces the O1–Sn1–S1
angle from the ideal value of 180° to the values of
161.79(9)° for molecule a and 162.63(9)° for molecule
b. The C20–Sn1–C30 = 117.93(11)° bond angle found in
molecule a differ significantly from the similar bond angle
of 126.01(12)° observed in molecule b.
Final R indices
[I [ 2r(I)]
R indices (all data)
0.0495; 0.1056
0.0496; 0.0871
0.0870; 0.1242
0.01167; 0.1072
Largest diff. peak and
´
0.172 and -0.240 0.710 and -0.649
-3
˚
hole (eA
)
Crystal Structure of [Ph2Sn(L)]ÁDMF
The ORTEP plot of [Ph2Sn(L)]ÁDMF is shown in Fig. 2
and consists of two crystallographically independent mol-
ecules (denoted by a and b) in the asymmetric unit. The
bond lengths and angles are summarized in Table 2. The
complex crystallizes in triclinic system and space group P¯ı.
In both molecules the ligand binds tridentately, forming
ONS-donor systems containing five- and six-membered
chelate rings. The index of trigonality (s) used to distin-
guish between tetragonal–pyramidal (s = 0) and trigonal-
bipyramidal (s = 1) geometries, defined by Addison and
The bond distances values of, respectively, 1.749(4),
1.289(5), 1.391(5), 1.330(5), 1.409(6), 1.362(6), and
´
˚
1.295(5) A, found in the skeleton S1–C11–N1–N2–C2–
C3–C4–O1 of molecule a, indicate that it has a conju-
gated double bond character. The shortening of the
˚
C11–N1 = 1.289(5) and C3–C4 = 1.362(6) A bonds, the
˚
lengthening of the S1–C11 = 1.749(4) A bond and the rup-
ture of C4–N1 bond upon complex formation, show that
123

J Chem Crystallogr (2011) 41:528–532
531
˚
Table 2 Selected bond distances (A) and angles for H2L and
[Ph2Sn(L)]ÁDMF
C2
H2L
[Ph2Sn(L)]Á
DMF (a)
[Ph2Sn(L)]Á
DMF (b)
N4
C3
S1–C11
1.6770(19)
1.352(2)
1.406(2)
1.280(3)
1.483(3)
1.536(3)
1.398(2)
1.749(4)
1.289(5)
1.391(5)
1.330(5)
1.409(6)
1.362(6)
1.295(5)
2.139(2)
2.150(2)
2.093(3)
2.5011(12)
2.184(3)
113.1(3)
124.1(4)
128.5(4)
114.7(4)
123.5(4)
117.93(11)
161.79(9)
84.25(12)
79.11(10)
1.755(5)
1.296(6)
1.395(5)
1.330(6)
1.410(6)
1.350(6)
1.293(5)
2.139(2)
2.134(2)
2.113(3)
2.5068(13)
2.163(4)
113.8(4)
123.8(4)
129.0(5)
114.4(4)
122.3(4)
126.01(12)
162.63(9)
83.51(13)
79.42(10)
N1–C11
C1
O2
N1–N2
N2–C2
C30a
C2–C3
S1a
N3a
C3–C4
O1–C4
C12a
Sn1–C20
Sn1–C30
Sn1–O1
C11a
N2a
Sn1a
N1a
Sn1–S1
C2a
O1a
C20a
Sn1–N2
C2–N2–N1
C3–C2–N2
C4–C3–C2
O1–C4–C5
O1–C4–C3
C20–Sn1–C30
O1–Sn1–S1
O1–Sn1–N2
N2–Sn1–S1
107.53(17)
114.81(18)
104.13(17)
112.57(16)
108.34(16)
C4a
C1a
C3a
C5a
Fig. 2 ORTEP plot of [Ph2Sn(L)]ÁDMF (molecule a) with the
displacement parameters drawn at the 30% probability level. The
dashed line indicates an intermolecular hydrogen bonding
3459, m(C=N) at 1640, and m(C=S) at 858 cm-1 bands
disappear, suggesting double deprotonation of the ligand
upon complex formation [2, 3]. However, a strong new
band observed at 1603 cm-1 is attributed to m(C=N–N=C)
stretching vibration [4]. The IR spectrum of the com-
plex also exhibits m(C=N) bands shifted to both higher
the double deprotonation of the ligand results in a con-
version from thione to thiolate sulfur. These results were
also observed in complex Ph2Sn[Ph(O)C=CH–C(Me)=
N–N=C(O)Ph] [4], which has a ONO-donor ligand. The
comparison among the bond parameters found in mole-
cules a and b is unremarkable.
and lower wave numbers at 1561 and 1519 cm-1
,
evidencing double deprotonation and ONS-tridentate
dibasic behavior of the ligand [4]. The far IR bands
observed at 527 cm-1 was tentatively assigned to the
m(Sn–O) mode.
Infrared Spectroscopy
The IR spectrum of [Ph2Sn(L)]ÁDMF, when compared
with that of the free ligand, shows that the m(O–H) at
Fig. 3 View of the packing
showing two intermolecular
interactions between DMF
solvate with molecules a and b
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J Chem Crystallogr (2011) 41:528–532
(1H, 13C) NMR Spectroscopy
Acknowledgments This work was sponsored by grants from CNPq
and FINEP (CT-INFRA 0970/01). GFS also gratefully acknowledges
the financial support of the Conselho Nacional de Desenvolvimento
The (1H, 13C) NMR spectra of the free ligand (H2L) mea-
sured in CDCl3 solution (see Fig. 1 for atom numbering)
show that it exists exclusively in the cyclic 5-hydroxy-4,
5-dihydropyrazoline form in solution. The signal of the
terminal CH3 appears at 2.11 ppm as a triplet, whereas the
magnetically and chemically nonequivalent CH2 methylene
hydrogens appear as a double doublet at 3.27 ppm
(JHH = 1.01 Hz); the N–H proton appears at 9.15 ppm.
Similar results have been reported by Zelenin and collabo-
rators [16, 17]. The 1H NMR spectrum (CDCl3) of
[Ph2Sn(L)]ÁDMF showed the appearance of two new signals
at 2.88 and 5.81 ppm assigned to –N(CH3)2 (DMF) and C3H
protons. This last peak strongly suggests that double
deprotonation of H2L give rise the tridentate bibasic
behavior of the ligand.
According to the 13C NMR spectroscopy, the spectrum
of H2L showed signal at 55.5 and 95.7 ppm assigned to C3
and C4, whereas the spectrum of the complex [Ph2Sn(L)]Á
DMF showed that these peaks were shifted from their
original positions to 94.7 and 162.5, respectively. This is
due to the rehybridization process of these atoms from
Csp3 to Csp2 with the ring-opening reaction upon complex
formation.
´
Cientıfico e Tecnologico-CNPq (Edital Universal-2007, Processo
307412/2008-3).
´
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Supporting Information Available
Crystallographic data for the structural analysis of the
compounds have been deposited at the Cambridge Crys-
tallographic Data Center (CCDC). The CCDC numbers are
778430 for [Ph2Sn(L)]ÁDMF and 778431 for (H2L). Copies
of the data can be obtained free of charge on application to
CCDC, 12 Union Road, Cambridge CB21EZ, United
Kingdom; Fax: ?44 1223 336033 or e-mail: deposit@ccdc.
cam.ac.uk.
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