Synthesis and characterization of tin(IV)/organotin(IV) complexes with 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT]: X-ray crystal structure of [SnCl3(BPCT)]

Article abstract of DOI:10.1080/00958972.2011.597849

Four new tin(IV)/organotin(IV) complexes, [SnCl₃(BPCT)] (2), [MeSnCl2(BPCT)] (3), [Me2SnCl(BPCT)] (4), and [Ph2SnCl(BPCT)] (5), have been synthesized by the direct reaction of 2-benzoylpyridine-N(4)- cyclohexylthiosemicarbazone [HBPCT, (1)] and

Full text of DOI:10.1080/00958972.2011.597849

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Synthesis and characterization of
tin(IV)/organotin(IV) complexes
with 2-benzoylpyridine-N(4)-
cyclohexylthiosemicarbazone [HBPCT]:
X-ray crystal structure of [SnCl (BPCT)]
3
a
a
a
M.A. Salam , M.A. Affan , Fasihuddin B. Ahmad , Ramli B.
b
c
c
Hitam , Zoltan Gal & Presly Oliver
a
Faculty of Resource Science and Technology, Universiti Malaysia
Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
b
Faculty of Science and Mathematics, Universiti Pendidikan
Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia
c
Oxford Diffraction Ltd., 10 Mead Road, Oxford Industrial Park,
OX5 1QU, UK
Published online: 12 Jul 2011.
To cite this article: M.A. Salam , M.A. Affan , Fasihuddin B. Ahmad , Ramli B. Hitam ,
Zoltan Gal & Presly Oliver (2011) Synthesis and characterization of tin(IV)/organotin(IV)
complexes with 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT]: X-ray crystal
structure of [SnCl (BPCT)], Journal of Coordination Chemistry, 64:14, 2409-2418, DOI:
3
10.1080/00958972.2011.597849
To link to this article: http://dx.doi.org/10.1080/00958972.2011.597849
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Journal of Coordination Chemistry
Vol. 64, No. 14, 20 July 2011, 2409–2418
Synthesis and characterization of tin(IV)/organotin(IV)
complexes with 2-benzoylpyridine-N(4)-cyclohexylthiosemicar-
bazone [HBPCT]: X-ray crystal structure of [SnCl (BPCT)]
3
M.A. SALAMy, M.A. AFFAN*y, FASIHUDDIN B. AHMADy, RAMLI
B. HITAMz, ZOLTAN GALx and PRESLY OLIVERx
yFaculty of Resource Science and Technology, Universiti Malaysia Sarawak,
9
4300 Kota Samarahan, Sarawak, Malaysia
zFaculty of Science and Mathematics, Universiti Pendidikan Sultan Idris,
5900 Tanjong Malim, Perak, Malaysia
xOxford Diffraction Ltd., 10 Mead Road, Oxford Industrial Park, OX5 1QU, UK
3
(
Received 8 January 2011; in final form 6 June 2011)
Four new tin(IV)/organotin(IV) complexes, [SnCl
[
3 2
(BPCT)] (2), [MeSnCl (BPCT)] (3),
2
Me SnCl(BPCT)] (4), and [Ph SnCl(BPCT)] (5), have been synthesized by the direct reaction
2
of 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT, (1)] and stannic chloride/
organotin(IV) chloride(s) in absolute methanol under purified nitrogen. HBPCT and its tin(IV)/
organotin(IV) complexes (2–5) were characterized by CHN analyses, molar conductivity,
1
UV-Vis, FT-IR, and H NMR spectral studies. In all the complexes, tin(IV) was coordinated
via pyridine-N, azomethine-N, and thiolato-S from 1. The molecular structure of 2 has been
determined by X-ray single-crystal diffraction analysis. Complex 2 is a monomer and the
central tin(IV) is six-coordinate in a distorted octahedral geometry. The crystal system of 2 is
˚
monoclinic with space group P121/n1 and the unit cell dimensions are a ¼ 8.3564(3) A,
˚
˚
b ¼ 23.1321(8) A, c ¼ 11.9984(4) A.
Keywords: Substituted thiosemicarbazone; Tin(IV)/organotin(IV) complexes; Spectral
analyses; Crystal structure
1. Introduction
Thiosemicarbazones are chelating ligands, bonding through the sulfur and hydrazine
nitrogen. Interest in tin(IV) thiosemicarbazones is focused on tin(IV) sulfur compounds
in biological molecules, with the bonding in tin(IV) chelates derived from the skeletal
¼
N–NH–C(S)–NH . Thiosemicarbazones and their organotin(IV) complexes are of
2
considerable interest due to their potential biological (namely antiviral and antitumor)
activities as well as their industrial and agricultural applications [1–4]. Synthesis and
biological studies of substituted thiosemicarbazones have received increasing attention
in recent years [5–8]. Mendes et al. [9] reported the synthesis of organotin(IV) complexes
*
Corresponding author. Email: maaffan@yahoo.com
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2011 Taylor & Francis
DOI: 10.1080/00958972.2011.597849

2
410
M.A. Salam et al.
of 2-pyridineformamide-derived thiosemicarbazone, which suggested that the com-
plexes possess an interesting pharmacological profile and are useful as cytotoxic and
antibacterial agents. Suni et al. [10] synthesized and characterized Co(II) and Co(III)
metal complexes with di-2-pyridylketone N(4)-cyclohexyl and N(4)-phenyl thiosemi-
carbazone ligands. However, most past works on thiosemicarbazones involved their
metal complexes with transition metal ions [11–16].
Many organotin(IV) compounds are investigated for their anticancer activity [17–20].
Survey of the literature found no report on the syntheses of tin(IV)/organotin(IV)
chelating 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone or its anticancer activity
and cytotoxicity. Continuing our work on organotin(IV) adducts with substituted
thiosemicarbazones [21–23], we report here the synthesis and structural characterization
of four new tin(IV)/organotin(IV) complexes (2–5) with 2-benzoylpyridine-N(4)-
cyclohexylthiosemicarbazone [HBPCT, (1)]. Single-crystal X-ray diffraction of
[
SnCl (BPCT)] (2) is also studied.
3
2
2
. Experimental procedure
.1. General procedure
All reagents were purchased from Fluka, Aldrich, and JT Baker. All solvents were
purified according to standard procedures [24]. UV-Vis spectra were recorded with
DMF on a Perkin Elmer Lambda 25 UV-Vis spectrophotometer. Infrared (IR) spectra
were recorded as KBr discs using a Perkin Elmer Spectrum GX Fourier-Transform
ꢀ
1
1
spectrometer (4000–375 cm ). H NMR spectra were recorded in CDCl solution on a
3
JEOL 500 MHz-NMR spectrophotometer. CHN analyses were recorded with a Flash
EA 1112 series CHN elemental analyzer. Molar conductance values were measured in
DMF using a Jenway 4510 conductivity meter. Finally, single-crystal X-ray crystallo-
graphic analyses were carried out using a CrysAlispro CCD diffractometer at Oxford
Diffraction Ltd. UK.
2
.2. Synthesis of N(4)-cyclohexylthiosemicarbazide
Cyclohexylisothiocyanate (1.41 g, 10 mmol) in 4 mL of ether was added dropwise into
mL of ether solution of hydrazine hydrate (2 g, 40 mmol). The mixture was stirred
4
vigorously for 5 h. Then, 5 mL petroleum ether was added into the resulting solution
and stirred for another 1 h forming white precipitate. The white precipitate was filtered
off, washed with a small amount of cold diethyl ether and dried in vacuo over silica gel.
ꢁ
ꢀ1
Yield: 2.12 g, 62%: m.p.: 146–148 C: FT-IR (KBr disc, cm ) ꢀmax: 3334 (s, NH2),
3
297 (s, NH), 2929, 2853 (s, cyclohexyl), 1349, 849 (w, C¼S).
2
.3. Synthesis of 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone
[
HBPCT, (1)]
N(4)-cyclohexylthiosemicarbazide (0.51 g, 3 mmol) was dissolved in dry methanol
10 mL) and mixed with a dry methanolic solution of 2-benzoylpyridine (0.54 g,
mmol) (10 mL). The resulting mixture was refluxed for 4 h (scheme 1) and cooled to
(
3

Organotin(IV) complexes
2411
room temperature. White microcrystals were formed and filtered off. The microcrystals
were washed several times with small amounts of cold methanol and subsequently with
cold hexane. The microcrystals were recrystallized from methanol and dried in vacuo over
ꢁ
silica gel. Yield: 0.94 g, 89%: m.p.: 174–176 C: UV-Vis (DMF) lmax/nm: 280, 300, 347: FT-
ꢀ1
IR (KBr disc, cm ) ꢀmax: 3335 (s, NH), 2938, 2845 (s, cyclohexyl), 1583 (w, C¼N), 984 (m,
1
N–N), 1345, 863 (w, C¼S), 608 (m, pyridine in plane). H NMR (CDCl ) ꢁ: 11.54 (s, 1H,
3
N1–H), 8.81 (d, 1H, pyridine ring C19–H), 7.76 (t, 1H, pyridine ring C17–H), 7.62 (d, 2H,
H of N2–H, 1H of CyC6–H), 7.53 (d, 1H, pyridine ring C16–H), 7.48 (t, 1H, pyridine ring
1
C18–H), 7.29–7.25 (m, 5H, phenyl ring), 2.11–1.71 (m, Cy–H). Anal. Calcd for
C H N S (%): C, 67.42; H, 6.55; N, 16.55. Found (%): C, 67.21; H, 6.31; N, 16.22.
1
9
22
4
2
.4. Synthesis of [SnCl (BPCT)] (2)
3
HBPCT (0.34 g, 1.0 mmol) was dissolved in absolute methanol (10 mL) under a nitrogen
atmosphere in a Schlenk round bottom flask. Then, a methanolic solution of stannic
chloride (0.26 g, 1.0 mmol) was added dropwise, resulting in a yellow solution. The
resulting reaction mixture was refluxed for 4 h (scheme 2) and cooled to room
temperature. Yellow microcrystals were obtained from slow evaporation of the solution
at room temperature. The microcrystals were filtered off, washed with a small amount
of cold methanol and dried in vacuo over silica gel. Single crystals were grown
from chloroform/methanol (1 : 1 ratio) at room temperature. Yield: 0.48 g, 80%;
ꢁ
ꢀ1
2
ꢀ1
m.p.: 281–283 C; molar conductance (DMF) ꢀ cm mol : 18.10; UV-Vis (DMF)
ꢀ
1
lmax/nm: 298, 370, 422; FT-IR (KBr, cm ) ꢀmax: 3329 (s, NH), 2931, 2852
(
(
s, cyclohexyl), 1596 (m, C¼N–N¼C), 1067 (w, N–N), 1307, 819 (m, C–S), 653
1
w, pyridine in plane), 449 (w, Sn–N). H NMR (CDCl ) ꢁ: 8.83 (d, 1H, pyridine ring
3
C19–H), 8.15 (t, 1H, pyridine ring C17–H), 8.10 (d, 1H, pyridine ring C16–H), 7.82
d, 2H, 1H of N2–H, 1H of CyC6–H), 7.55–7.25 (m, 6H, 1H of pyridine ring C18–H,
H of phenyl ring), 2.20–1.72 (m, CyC–H). Anal. Calcd for C H Cl N SSn (%):
(
5
1
9
21
3
4
C, 40.57; H, 3.76; N, 10.03. Found (%): C, 40.41; H, 3.63; N, 9.92.
Scheme 1. Synthesis of 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT, (1)].

2
412
M.A. Salam et al.
Scheme 2. The reaction scheme for the synthesis of 2–5.
The other complexes (3–5) were synthesized using a similar procedure to 2 using
appropriate organotin(IV) chloride(s).
2
.5. Synthesis of [MeSnCl (BPCT)] (3)
2
ꢁ
ꢀ1
2
Yield: 0.48 g, 84%: m.p.: 202–204 C: Molar conductance (DMF) ꢀ cm mol : 11.3:
ꢀ1
ꢀ
1
UV-Vis (DMF) lmax/nm: 295, 334, 385, 417: FT-IR (KBr, cm ) ꢀmax: 3360 (s, NH),
2
933, 2852 (s, cyclohexyl), 1596 (m, C¼N–N¼C), 1028 (w, N–N), 1308, 816 (m, C–S),
1
2
119
6
49 (w, pyridine in plane), 578 (w, Sn–C), 484 (w, Sn–N). H NMR (CDCl , J[ Sn,
3
1
H]) ꢁ: 8.83 (d, 1H, pyridine ring C19–H), 8.01 (t, 1H, pyridine ring C17–H), 7.96
d, 1H, pyridine ring C16–H), 7.66 (d, 2H, 1H of N2–H, 1H of CyC6–H), 7.51–7.25
(

Organotin(IV) complexes
2413
(
(
m, 6H, 1H of pyridine ring C18–H, 5H of phenyl ring), 2.15–1.73 (m, CyC–H), 1.08
s, 3H, Sn–CH ), [92.5 Hz]. Anal. Calcd for C H N SSnCl (%): C, 44.31; H, 4.46; N,
3
20 24
4
2
1
0.33. Found (%): C, 44.31; H, 4.38; N, 10.27.
2
.6. Synthesis of [Me SnCl(BPCT)] (4)
2
ꢁ
ꢀ1
2
Yield: 0.45 g, 81%: m.p.: 180–182 C: Molar conductance (DMF) ꢀ cm mol : 12.84:
ꢀ1
ꢀ
1
UV-Vis (DMF) lmax/nm: 298, 339, 386, 412: FT-IR (KBr, cm ) ꢀmax: 3335 (s, NH),
2
939, 2852 (s, cyclohexyl), 1583 (m, C¼N–N¼C), 1074 (w, N–N), 1320, 833 (m, C–S),
1
2
119
6
52 (w, pyridine in plane), 531 (w, Sn–C), 479 (w, Sn–N). H NMR (CDCl , J[ Sn,
3
1
H]) ꢁ: 8.82 (d, 1H, pyridine ring C19–H), 8.55 (t, 1H, pyridine ring C17–H), 7.76
d, 1H, pyridine ring C16–H), 7.63 (d, 2H, 1H of N2–H, 1H of CyC6–H), 7.47–7.25
m, 6H, 1H of pyridine ring C18–H, 5H of phenyl ring), 2.15–1.63 (m, CyC–H), 1.17
s, 6H, Sn–CH ), [110 Hz]. Anal. Calcd for C H N SSnCl (%): C, 48.34; H, 5.21;
(
(
(
3
21 27
4
N, 10.73. Found (%): C, 48.28; H, 5.14; N, 10.62.
2
.7. Synthesis of [Ph SnCl(BPCT)] (5)
2
ꢁ
ꢀ1
2
Yield: 0.52 g, 76%: m.p.: 192–195 C: Molar conductance (DMF) ꢀ cm mol : 8.15:
ꢀ1
ꢀ
1
UV-Vis (DMF) lmax/nm: 295, 306, 368, 417: FT-IR (KBr, cm ) ꢀmax: 3379 (s, NH),
2
6
(
929, 2851 (s, cyclohexyl), 1592 (m, C¼N–N¼C), 1020 (w, N–N), 1302, 811 (m, C–S),
1
36 (w, pyridine in plane), 588 (w, Sn–C), 457 (w, Sn–N). H NMR (CDCl ) ꢁ: 8.82
d, 1H, pyridine ring C19–H), 8.60 (t, 1H, pyridine ring C17–H), 8.55 (d, 1H, pyridine
3
ring C16–H), 7.70 (d, 2H, 1H of N2–H, 1H of CyC6–H), 7.27–7.25 (m, 16H, 1H of
pyridine ring C18–H, 15H of phenyl ring), 2.15–1.74 (m, Cy–H). Anal. Calcd for
C H N SSnCl (%): C, 57.65; H, 4.83; N, 8.67. Found (%): C, 57.34; H, 4.62; N, 8.48.
3
1
31
4
3
. Results and discussion
HBPCT was prepared by the condensation of cyclohexylthiosemicarbazide and
-benzoylpyridine in absolute methanol in 1 : 1 mole ratio. It has two tautomers
within the structure, existing as either thione or thiol tautomer (scheme 1). Four new
2
tin(IV)/organotin(IV) complexes (2–5) with 1 were synthesized in acceptable yields
(scheme 2). The physical properties and analytical data of 1–5 are given in section 2.
Complexes 2–5 are solids and are stable under N . They are more soluble in polar than
2
in nonpolar solvents. Complexes 2–5 are proposed to have octahedral configuration; all
are neutral and nonelectrolytes [25].
3
.1. UV-Vis spectroscopy
ꢀ
4
ꢀ1
The UV-Vis spectra of 1–5 were carried out in DMF (10 mol L ) at room
temperature. 1 exhibited three bands at 280, 300, and 347 nm assigned to the HOMO/
LUMO transition of pyridine, azomethine, thiolate functions and benzene ring system,
respectively [26]. On complexation, the UV-Vis spectra of 2–5 exhibit one new

2
414
M.A. Salam et al.
absorption at 412–422 nm, assigned to the HOMO/LUMO transition of the ligand–
metal charge transfer [27]. The shift of the HOMO/LUMO band from the ligand to the
complexes was a clear indication that coordination occurred between tin(IV) and 1.
3
.2. IR spectroscopy
The IR spectrum of 1 displayed absorptions at 3335, 2938, 2845, 1583, 984, 1345, 863,
ꢀ
1
and 608 cm attributable to ꢀ(NH), ꢀ(cyclohexyl), ꢀ(C¼N), ꢀ(N–N), ꢀ(C¼S), and
pyridine in plane, respectively. Upon complexation, several significant changes
ꢀ
1
occurred. The spectrum of the free ligand exhibits a strong band at 1583 cm due to
ꢀ
(C¼N). The newly formed C¼N–N¼C bond showed medium to strong absorptions at
ꢀ1
1
to tin(IV) [28]. The ꢀ(N–N) at 984 cm
1
This is further supported by the formation of a new ꢀ(Sn–N) at 449–484 cm in 2–5
[29]. The ꢀ(C¼S) and bending vibrations observed at 1345 and 863 cm in the spectrum
of 1 shift to lower frequencies, 1302–1320 and 811–833 cm , in spectra of 2–5,
583–1596 cm in spectra of 2–5, indicating coordination of azomethine nitrogen (N3)
ꢀ
1
in 1 is shifted to higher frequencies,
020–1074 cm , in 2–5, supporting the coordination of azomethine nitrogen to Sn(IV).
ꢀ
1
ꢀ
1
ꢀ1
ꢀ1
suggesting coordination of tin(IV) through sulfur after deprotonation and formation of
ꢀ
1
thiolate sulfur [30, 31]. The pyridine in-plane sharp band at 608 cm in free 1 shifts to
ꢀ
1
48–699 cm in 2–5, suggesting coordination of the pyridine nitrogen to tin(IV) [32].
6
Based on the IR spectra of 2–5, substituted thiosemicarbazone coordinates through
azomethine-N, pyridine-N, and thiolato-S.
1
.3. H NMR spectra
3
1
The H NMR spectra of 1–5 were interpreted based on the atom labeling in scheme 2.
In HBPCT a singlet at 11.54 ppm indicates a proton at N1–H. The pyridyl protons have
four resonances; two doublets at 8.81 and 7.53 ppm correspond to C19–H and C16–H,
while two triplets at 7.76 and 7.48 ppm belong to C17–H and C18–H, respectively. The
proton resonance on N2 and CyC6–H appear as a doublet at 7.76 ppm which is
overlapping. The aromatic resonances of the ligand were observed as multiplets at
7
.29–7.25 ppm. In the cyclohexyl, the equatorial protons were observed at 2.11 ppm
1
compared to their axial protons at 1.71 ppm. Upon complexation, the H NMR spectra
of 2–5 undergo some changes in chemical shifts as a result of coordination. The N1–H
signal was absent in spectra of 2–5, indicating deprotonation and coordination of
thiolate sulfur to tin(IV). The C19–H resonance was observed at 8.83–8.82 ppm in 2–5,
shifted downfield compared to 1, supporting coordination through pyridyl nitrogen
(N4). The C18–H resonance of the pyridine ring probably overlaps with aromatic ring
protons at 7.55–7.25 ppm in 2–5, downfield compared to the free ligand. C17–H and
C16–H of pyridine were downfield compared to 1. Some aromatic resonances are
multiplets, making it difficult to distinguish the individual signals. A doublet at
7
groups attached to tin(IV) in 3 and 4 give a singlet at 1.08 and 1.17 ppm, respectively.
.82–7.63 ppm in 2–5 corresponds to N2–H and CyC6–H overlapping. The methyl
2
The J[ Sn, H] values, 92.5 Hz for 3 and 110 Hz for 4, support the six-coordinate
119
1
environments around tin(IV) [33].

Organotin(IV) complexes
2415
Figure 1. Molecular structure of 2.
3.4. X-ray crystallography diffraction analyses
The molecular structure of 2 is shown in figure 1 together with the atomic numbering.
Crystal data and structural refinement parameters are given in table 1. Selected bond
˚
ꢁ
lengths (A) and angles ( ) are given in table 2. In the molecular structure of 2, Sn adopts a
distorted octahedral geometry with 1 coordinated as a mononegative tridentate chelating
agent via pyridine-N, azomethine-N, and thiolato-S. The distorted octahedral tin(IV) has
meridional chlorides. Cl2 and Cl1 are trans to each other, while Cl3 is trans to N14.
˚
The two trans chlorides show slightly longer bond lengths [d(Sn–Cl1) ¼ 2.433(1) A and
˚
˚
d(Sn–Cl2) ¼ 2.415(1) A] in [SnCl (FPT)] to 2.4289(5) and 2.4306(4) A to tin(IV), whereas
3
˚
˚
the trans chloride and nitrogen [d(Sn–Cl3) ¼ 2.360(1) A and d(Sn–N2) ¼ 2.194(2) A] in
˚
SnCl (FPT)] to 2.3610(5) and 2.1906(16) A were observed [34]. The Sn1–S17 bond
3
[
˚
˚
distance is 2.4474(5) A, close to the sum of the covalent radii of tin and sulfur 2.42 A [35],
˚
but much smaller than the van der Waals radii 4.0 A [36], confirming sulfur is coordinated
in the thiolate form. The Sn1–N14 and Sn1–N1 bond lengths are 2.1907(16) and
˚ ˚
.2047(15) A, respectively, close to the sum of the covalent radii of Sn–N (2.15 A),
2
indicating strong bond interaction of Sn1 with N14 and N1 [37]. The N14–C7 and
˚
N15–C16 bond distances are 1.307(2) and 1.333(2) A, respectively, in conformity with a

2
416
M.A. Salam et al.
Table 1. Crystal data, structure solution, and refinement for 2.
Compound
[SnCl
C
562.50
150(2)
0.71073
3
(BPCT)] (2)
SSn
Empirical formula
Formula weight
Temperature (K)
19
H
3 4
21Cl N
˚
Wavelength (A)
Crystal system
Space group
Unit cell dimensions (A, )
Monoclinic
P121/n1
˚
ꢁ
a
b
c
ꢂ
ꢃ
ꢄ
8.3564(3)
23.1321(8)
11.9984(4)
90.0
106.139(4)
90.0
2227.93(13), 4
1.677
o
M -Ka
3
˚
Volume (A ), Z
Calculated density (mg m
ꢀ
3
)
˚
Radiation type l (A)
F(000)
1120
0.599 ꢂ 0.248 ꢂ 0.17
3
Crystal size (mm )
Crystal color
Scan range ꢅ ( )
Absorption coefficient (ꢆ) (mm
Absorption correction
Max. and min. transmission
Yellow
3.1723–26.3154
1.613
ꢁ
ꢀ1
)
Multi-scan
1.0 and 0.83781
1.023
2
Goodness-of-fit on F
Data/restraints/parameters
3910/0/253
Final R indices [I 4 2ꢇ(I)]
R
1
¼ 0.0206,
wR
¼ 0.0447
¼ 0.0276,
wR
¼ 0.0462
2
R indices (all data)
R
1
2
˚
Table 2. Selected bond lengths (A) and angles ( ) of 2.
ꢁ
Sn1–Cl1
Sn1–Cl2
Sn1–S14
Sn1–Cl3
Sn1–N14
Sn1–N1
S17–C16
C6–N1
2.4289(5)
2.4306(5)
2.4474(5)
2.3610(5)
2.1907(16)
2.2047(15)
1.760(2)
1.349(2)
1.390(3)
1.478(3)
1.346(2)
1.307(2)
1.474(3)
1.325(3)
1.333(2)
1.333(2)
1.383(3)
1.521(3)
1.378(3)
1.374(3)
1.477(3)
1.389(3)
1.395(3)
Cl1–Sn1–Cl2
Cl1–Sn1–S17
Cl2–Sn1–S17
Cl3–Sn1–Cl1
Cl3–Sn1–Cl2
Cl3–Sn1–S17
N14–Sn1–Cl1
N14–Sn1–Cl2
N14–Sn1–S17
N14–Sn1–Cl3
N14–Sn1–N1
N18–C19–C24
N15–N14–Sn1
N1–Sn1–Cl1
N1–Sn1–Cl2
N1–Sn1–S17
N1–Sn1–Cl3
N1–C2–C3
171.129(17)
93.509(19)
94.334(19)
90.479(19)
90.941(19)
108.609(18)
87.29(4)
89.89(4)
80.69(4)
170.57(4)
73.92(6)
110.11(15)
121.01(11)
86.41(4)
84.73(4)
154.58(4)
96.81 (4)
121.89(19)
119.95(18)
120.10(18)
120.63(16)
119.07(18)
118.35(19)
C6–C5
C6–C7
N14–N15
N14–C7
N18–C19
N18–C16
N15C16
N1–C2
C5–C4
C19–C24
C3–C2
C3–C4
C7–C8
C8–C13
C8–C9
C5–C6–N1
C3–C4–C5
C2–N1–C6
C4–C5–C6
C4–C3–C2

Organotin(IV) complexes
2417
˚
formal C¼N double bond (1.28 A). The values are similar, indicating the consistency of
the thiol tautomeric form. Although the latter are a little longer than the former, these
differences in bond distance are due to delocalization along N15–C16–S17. It is clear
from the structural study that the complex is by elimination of HCl from the interaction
of the SH group of the thiol form of 1 and SnCl . Therefore, the C16–S17 bond changes
4
from a double bond to a predominately single bond, whereas C16–N15 acquires some
double bond characteristics. Two trans chlorides have Cl2–Sn1–Cl1 angle of
ꢁ
1
71.129(17) , showing significant distortion from linear. The S17–Sn1–N1 bond angle
ꢁ
ꢁ
(154.58(4) ) is much less than expected. The sum of the angles S17–Sn1–N14 (80.69(4) ),
N14–Sn1–N1 (73.92(6) ), and S17–Sn1–N1 (154.58(4) ) is 309.19 , showing distortion.
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
The sum of the angles S17–Sn1–Cl3 (108.609(18) ), S17–Sn1–N14 (80.69(4) ), N14–Sn1–
ꢁ
ꢁ
ꢁ
N1 (73.92(6) ), and Cl3–Sn1–N1 (96.81(4) ) is 360 , thus Cl3, Sn1, S17, N1, and N14 are
ꢁ
coplanar. In the pyridine ring, the angles are C2–N–C6 (120.63(16) ), N1–C2–C3
ꢁ ꢁ ꢁ
(
(
121.89(19) ), C2–C3–C4 (118.35(19) ), C3–C4–C5 (120.11(18) ), C4–C5–C6
119.07(18) ), and C5–C6–N1 (119.95(15) ); thus all the atoms in the pyridine ring are
ꢁ
ꢁ
not the same, perhaps due to the electronic effect of the adjacent electronegative pyridyl
nitrogen.
4
. Conclusion
HBPCT and its tin(IV)/organotin(IV) complexes (2–5) were synthesized and charac-
terized. 2–5 are proposed to be six-coordinate, where 1 is coordinated to tin(IV)
through thiolato-S, azomethine-N, and pyridine ring-N. X-ray diffraction has revealed
that 2 is a distorted octahedron.
Supplementary material
CCDC reference number 782929 contains the supplementary crystallographic data for
[SnCl (BPCT)] (2). This data can be obtained free of charge from the Cambridge
3
Crystallographic Data Center via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
This work was financially supported by the Ministry of Science, Technology and
Innovation (MOSTI) under research grant (No. 06-01-09-SF0046). The authors thank
Universiti Malaysia Sarawak (UNIMAS) for the facilities to carry out the research
work. The authors are also grateful to Zultan Gal, Oxford Diffraction Ltd. UK, for the
X-ray diffraction analysis.

2
418
M.A. Salam et al.
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1