Syntheses and characterization of organotin(IV) complexes derived from 2-mercapto-1,3,4-thiadiazole

Article abstract of DOI:10.1002/hc.21046

Four organotin complexes of the types [(Ph₃Sn)(C ₂HN₂S₂)] (1), [(CH₃) ₃Sn(C₂HN₂S₂)]_n (2), [(Bu₂Sn)(C₂HN₂S_2<

Full text of DOI:10.1002/hc.21046

Heteroatom Chemistry
Volume 00, Number 0, 2012
Syntheses and Characterization of
Organotin(IV) Complexes Derived from
2-Mercapto-1,3,4-thiadiazole
Qingfeng Wang,1 Chunlin Ma,2 Guofang He,1 and Yanfei Li1
1Department of Chemistry, Taishan University, Taian 271021, People’s Republic of China
2Department of Chemistry, Liaocheng University, Liaocheng 252059, People’s Republic of China
Received 5 January 2012; revised 20 July 2012
been reported several times before [1–8], as well as
ABSTRACT:
of the
Four
types
organotin
[(Ph3Sn)(C2HN2S2)]
complexes
(1),
the versatile molecular structure and supramolec-
ular architecture exhibited by these complexes [9–
11]. Among them, an organotin heterocyclic thiol
complex is a interesting field because of their bio-
logical activity as well as their variable molecular
structures [12–15]. As an extension of this research
program, we selected 2-mercapto-1,3,4-thiadiazole
as a heterocyclic thiol ligand and obtained four
organotin heterocyclic thiol complexes by using this
ligand with organotin chloride. In this paper, we
report the synthesis and characterization of these
organotin complexes.
[(CH3)3Sn(C2HN2S2)]n (2), [(Bu2Sn)(C2HN2S2)2]
(3), and [(Me2Sn)4(C2HN2S2)2(μ3-O)2(C2H5O)2] (4)
have been obtained by 2-mercapto-1,3,4-thiadiazole
and triorganotin chloride or diorganotin dichloride.
All the complexes were characterized by elemental
analysis, IR and NMR spectroscopy, and X-ray
diffraction analyses, which revealed that complexes
1 and 3 are mononuclear structures, complex 1 can
further form a one-dimensional (1D) helical chain,
and complex 3 can further form a 22-membered
macrocycle through the intermolecular C H· · ·N
hydrogen bond; complex 2 is a 1D infinite chain
linked by intermolecular N→Sn and S→Sn bonding
interactions; complex 4 is a typical ladder structure.
EXPERIMENTAL
ꢀ
C
Materials and Measurements
2012 Wiley Periodicals, Inc. Heteroatom Chem 00:1–8,
2012; View this article online at wileyonlinelibrary.com.
DOI 10.1002/hc.21046
All reagents were commercially available, and they
were used without further purification. The melting
points were obtained with X-4 digital micromelt-
ing point apparatus and were uncorrected. Infrared
spectra were recorded on a Nicolet-5700 spectropho-
tometer (Thermo Nicolet Corporation, Madison, WI)
using KBr disks and sodium chloride optics. 1H
and 119Sn NMR spectra were recorded on a Var-
ian Mercury Plus 400 spectrometer (Varian Medical
Systems, Palo Alto, CA) operating at 400 and 149.2
MHz, respectively. The spectra were acquired at 298
K. The chemical shifts were reported in ppm with
respect to the references and were stated relative
INTRODUCTION
Organotin complexes have attracted more and more
attention in recent years, owing to their determi-
nate or potential pharmaceutical value, which have
Correspondence to: Qingfeng Wang; e-mail: wangqingfeng100@
126.com.
Contract grant sponsor: National Natural Foundation, People’s
Republic of China.
1
c
ꢀ
to external tetramethylsilane for H NMR and neat
2012 Wiley Periodicals, Inc.
1

2
Wang et al.
tetramethyltin for 119Sn NMR. Elemental analyses
(C, H, N) were performed with a PE-2400II appara-
tus (Perkin Elmer, Waltham, MA).
[(Me2Sn)4(C2HN2 S )2(μ3 − O)2(C2 H O)2](4).
2
5
The procedure is similar to that of complex 1.
2-Mercapto-1,3,4-thiadiazole (0.118 g, 1 mmol),
sodium ethoxide (0.068 g, 1 mmol), and Me2SnCl2
(0.438 g, 2 mmol) were added to the solution
of benzene (20 mL), continuing the reaction for
12 h at 40◦C. The solid was recrystallized from
ether, and colorless crystals were formed. Yield:
68%. mp 171–173◦C. Anal. Found: C 20.37, H 3.95,
N 5.58. Calcd for C16H36N4O4S4Sn4: C 20.19, H
3.81, N 5.89. IR (KBr, cm−1): ν(S C N) 1553,
ν(C S) 966, ν(O Sn O) 652, ν(Sn N) 439. 1H
[(Ph3Sn)(C2HN2 S )] (1). The reaction was car-
2
ried out under nitrogen atmosphere. 2-Mercapto-
1,3,4-thiadiazole (0.118 g, 1 mmol), sodium ethoxide
(0.068 g, 1 mmol), and Ph3SnCl (0.385 g, 1 mmol)
were added to the solution of benzene (20 mL), con-
tinuing the reaction for 12 h at 40◦C. The solid was
recrystallized from ether, and colorless crystals were
formed. Yield: 75%. mp 147–149◦C. Anal. Found: C
51.67, H 3.59, N 5.73. Calcd for C20H16N2S2Sn: C
51.42, H 3.45, N 6.05. IR (KBr, cm−1): ν(S C N),
NMR (CDCl3, ppm): δ 8.36 (s, 2H, CH N), 0.95
2
(s, 24H, Sn CH3, J119
= 84.2 Hz); 13C NMR
1
(CDCl3. ppm): 165.1 (C S HSn), 152.4 (CH N), 14.2
Sn
1
1551; ν(C S), 977; ν(Sn S), 335. H NMR (CDCl3,
1
(Sn CH3, J119
= 615 Hz). 119Sn NMR (CDCl3,
ppm): δ 8.35 (s, 1H, CH N), 7.28–7.61 (m, 15H, Ph-
13
ppm): −121.7, −1C57.4.
Sn
H). 13C NMR (CDCl3. ppm): 168.3 (C S Sn), 150.5
(CH N), 137.6 (1 J119
= 538 Hz), 134.9 (2 J119
13
13
Sn
= 34 Hz), 130.7, 129.4C(Ar–C); 119Sn NMR (CDSCn l3C,
X-Ray Crystallography
ppm): 78.4.
Data were collected at 298 K on a Bruker SMART
CCD 1000 diffractometer fitted with Mo Kα radia-
tion. The structures were solved by direct methods
and refined by a full-matrix least squares procedure
based on F2 using the SHELXL-97 program system.
All non-hydrogen atoms were included in the model
at their calculated positions. The positions of hydro-
gen atoms were calculated, and their contributions
to structural factor calculations were included. Crys-
tal data and experimental details of the structure de-
terminations are presented in Table 1.
[(CH3)3Sn(C2HN2 S )]n (2). The procedure is
2
similar to that of complex 1. 2-Mercapto-1,3,4-
thiadiazole (0.118 g, 1 mmol), sodium ethoxide
(0.068 g, 1 mmol), and Me3SnCl (0.199 g, 1 mmol)
were added to the solution of benzene (20 mL), con-
tinuing the reaction for 12 h at 40◦C. The solid was
recrystallized from ether, and colorless crystals were
formed. Yield: 73%. mp 155–157◦C. Anal. Found:
C 21.08, H 3.75, N 9.71. Calcd for C5H10N2S2Sn: C
21.37, H 3.59, N 9.97. IR (KBr, cm−1): ν(S C N)
1
1549, ν(C S) 953, ν(Sn S) 344, ν(Sn N) 447. H
NMR (CDCl3, ppm): δ 8.40 (s, 1H, CH N), 0.92
2
(s, 9H, CH3, J119
= 81.6 Hz). 13C NMR (CDCl3.
RESULTS AND DISCUSSION
1
Sn
H
ppm): 167.8 (C S Sn), 153.7 (CH N), 13.8 (CH3,
Synthesis of Complexes 1–4
1 J119
= 504 Hz). 119Sn NMR (CDCl3, ppm): 27.5.
13
Sn
C
The synthetic procedure is shown in Scheme 1.
[(Bu2Sn)(C2HN2 S )2](3). The procedure is sim-
2
ilar to that of complex 1. 2-Mercapto-1,3,4-
thiadiazole (0.236 g, 2 mmol), sodium ethoxide
(0.136 g, 2 mmol), and Bu2SnCl2 (0.325 g, 1 mmol)
were added to the solution of benzene (20 mL), con-
tinuing the reaction for 12 h at 40◦C. The solid was
recrystallized from ether, and colorless crystals were
formed. Yield: 71%. mp 132–134◦C. Anal. Found: C
30.69, H 4.55, N 12.21. Calcd for C12H20N4S4Sn : C
30.84, H 4.31, N 11.99. IR (KBr, cm−1): ν(S C N)
IR Spectroscopic Studies of Complexes 1–4
The stretching frequencies of interest are those as-
sociated with the Sn S and Sn N groups. The ex-
plicit features in the infrared spectra of complexes
1–3 are strong absorption appearing in the range of
335–344 cm−1 in respective complexes, which are ab-
sent in the free ligand and could be assigned to the
Sn S stretching mode [16]. While for complexes 2
and 4, new bands at 447 and 439 cm−1 in respective
spectra are assigned to ν(Sn N), indicating the ni-
trogen atom from the ligand moiety coordinates to
the central tin atom [17]; moreover, the strong peak
at 652 cm−1 in complex 4 is assigned to ν (O Sn O),
indicating the O Sn O bridging structure in com-
plex 4 [18].
1
1552, ν(C S) 958, ν(Sn S) 342. H NMR (CDCl3,
ppm): δ 8.46 (s, 2H, CH N), 0.89 (s, 6H, CH3), 1.26–
1.54 (m, 12H, Sn CH2 CH2 CH2, 2 J119
= 73 Hz).
1
Sn
H
13C NMR (CDCl3, ppm): 166.4 (C S Sn), 151.8
(CH N), 29.1 (2 J119
= 46 Hz), 26.8 (3 J119
= 108
13
13
Sn
C
Hz), 25.3 (1 J119
= 498 Hz), 13.8 (Sn C SnCC C C).
13
Sn
C
119Sn NMR (CDCl3, ppm): 43.2.
Heteroatom Chemistry DOI 10.1002/hc

Syntheses and Characterization of Organotin(IV) Complexes Derived from 2-Mercapto-1,3,4-thiadiazole
3
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Heteroatom Chemistry DOI 10.1002/hc

4
Wang et al.
SCHEME 1
and complex 4 is five coordinated. These data are
confirmed by the X-ray crystal structures of com-
plexes 1,3, and 4; whereas complex 2 has the sig-
nals in 27.5 ppm, thus indicating four-coordinated
environment around the tin atoms for complex 2;
which is not accordant with the structure in solid
state. It can reasonably be assumed that the Sn N
dative bond of complex 2 is probably broken in the
solution.
NMR Data of Complexes 1–4
1
The H NMR data show that the signal of the SH
proton in the spectrum of the free ligand is ab-
sent in complexes 1–3, indicating the removal of
the SH proton and the formation of Sn S bond.
The structural changes occurring in the ligand upon
deprotonation and coordination to the tin atom
could be reflected by the changes in the 13C NMR
spectra of complexes. The 13C NMR spectra of all
complexes 1–4 show a downfield shift of all carbon
resonances compared with the free ligand, which in-
dicates the formation of the tin complexes [19,20].
Furthermore, in solution the C Sn C angles esti-
Crystal Structure of Complexes 1 and 2
The molecular structure or repeating unit of com-
plexes 1 and 2 are illustrated in Figs. 1–3 and 4 along
with 5, respectively; selected bond lengths and bond
angles are given in Tables 2 and 3, respectively. Com-
plex 1 has the common structural property with a
monomeric coordination structure. The tin atom is
four-coordinated tetrahedron geometry. The Sn S
mated by 1 J119
coupling constants as reported in
13
Sn
C
the literature are 119◦ for complex 2 and 130◦ for
complex 4 [21], which are basically consistent with
the C Sn C angles in solid state. The 119Sn NMR
spectra of complexes 1–4 show resonances between
27.5 and −157.4 ppm. As reported in the literature
[22], values of δ (119Sn) in the ranges −210 to −400,
−90 to −190, and 200 to −60 ppm have been asso-
ciated with six-, five-, and four-coordinated tin cen-
ters, respectively. On this basis, we can conclude that
complexes 1 and 3 are typical of four coordinated
˚
bond length in complex 1 is 2.4677(14) A, which
approaches the range reported for triphenyltin
˚
heteroarenethiolates (2.405–2.481 A) and the sum
˚
of the covalent radii of tin and sulfur (2.42 A) [23],
showing the sulfur atom coordinates to the tin atom
Heteroatom Chemistry DOI 10.1002/hc

Syntheses and Characterization of Organotin(IV) Complexes Derived from 2-Mercapto-1,3,4-thiadiazole
5
FIGURE 1 Molecular structure of complex 1.
FIGURE 3 View of the 1D helical chain of complex 1 from c
axis, propagation via intermolecular C H...N hydrogen bond
interactions.
FIGURE 4 Repeating unit of complex 2.
by a covalent bond. Furthermore, the C H· · ·N hy-
drogen bond is found in complex 1, which con-
nects the adjacent molecules to give rise to a one-
dimensional (1D) helical chain, the N(2)· · ·H(11) and
˚
C(11)-H(11) distances are 2.554 and 0.931 A, respec-
tively, and the C H· · ·N angle is 166.43◦. These data
are similar to other triorganotin complexes that have
been reported [24].
Complex 2 exhibit a infinite 1D polymeric chain
structure via the tin and nitrogen atoms from the
ligand coordinating to the tin atom. All the tin atoms
are five-coordinated geometry with slight distortion
from an ideal trigonal bipyramidal. The distortion
lies at the angle of N(1)–Sn(1)–S(1)#1 is 174.3(2)◦,
FIGURE 2 1D helical chain of complex 1, propagation via
intermolecular C H· · ·N hydrogen bond interactions.
Heteroatom Chemistry DOI 10.1002/hc

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Wang et al.
FIGURE 5 1D infinite chain of complex 2.
which is slightly deviated from the normal angle of
180◦. Three methyl groups defined at the equatorial
plane, and the axial positions are occupied by the
sulfur and nitrogen atoms. The bond length of Sn(1)–
tively; selected bond lengths and bond angles are
given in Tables 4 and 5, respectively. In complex
3, two carbon atoms and two sulfur atoms are co-
valently linked to the tin atom, so the tin atom is
four-coordinated tetrahedron geometry, The Sn C
˚
S(2) is 2.591(3) A, which is longer than the sum of
˚
˚
distances [from 2.130(5) to 2.135(4) A] are close
the covalent radii of tin and sulfur (2.42 A), but much
to those found in (n-Bu)2Sn(SC5H5N2)2 [28]. The
shorter than the sum of the van der Waals radii of
˚
˚
˚
Sn S distances [2.5506(11) A and 2.5545(13) A] are
little longer than those found in complex 1 and little
shorter than those found in complex 2. Similar to
complex 1, the C H· · ·N hydrogen bond is found in
complex 3, which connects the adjacent molecules
to give rise to a 22-membered macrocycle structure,
tin and sulfur (4.0 A) [23]. The Sn(1)–N(2)#1 bond
˚
length (2.541(10) A) is longer than the covalent radii
˚
of tin and nitrogen (2.15 A) [25], but shorter than
those found in other similar triorganotin complexes
[26,27].
˚
˚
the width of the macrocycle is 9.307 A × 3.982 A
[transannular N(2)· · ·N(2a) and N(3)· · ·N(4)], which
is similar to those found in other complex [29].
Complex 4 is a typical ladder structure. It con-
sists of Sn4O4 ladders with one nitrogen atom from
Crystal Structure of Complexes 3 and 4
The molecular structure of complexes 3 and 4 are
illustrated in Figs. 6 along with 7 and 8, respec-
◦
˚
TABLE 2 Selected Bond Lengths (A) and Bond Angles ( ) for Complex 1
Bond lengths
Sn(1)–C(15)
Sn(1)–C(3)
2.128(5)
2.128(4)
Sn(1)–C(9)
Sn(1)–S(2)
2.146(4)
2.4677(14)
Bond angles
C(15)–Sn(1)–C(3)
C(3)–Sn(1)–C(9)
C(3)–Sn(1)–S(2)
119.01(17)
112.31(17)
108.79(11)
C(15)–Sn(1)–C(9)
C(15)–Sn(1)–S(2)
C(9)–Sn(1)–S(2)
107.50(17)
111.36(14)
95.33(12)
◦
˚
TABLE 3 Selected Bond Lengths (A) and Bond Angles ( ) for Complex 2
Bond lengths
Sn(1)–C(5)
Sn(1)–C(3)
Sn(1)–S(2)
2.074(12)
2.162(12)
2.591(3)
Sn(1)–C(4
Sn(1)–N(2)#1
2.109(11)
2.541(10)
Bond angles
C(5)–Sn(1)–C(4)
C(4)–Sn(1)–C(3)
C(4)–Sn(1)–N(2)#1
C(5)–Sn(1)–S(2)
C(3)–Sn(1)–S(2)
117.8(5)
C(5)–Sn(1)–C(3)
C(5)–Sn(1)–N(2)#1
C(3)–Sn(1)–N(2)#1
C(4)–Sn(1)–S(2)
121.2(6)
83.0(5)
84.4(5)
99.8(3)
174.3(2)
118.0(6)
85.5(4)
96.4(4)
91.1(4)
N(2)#1–Sn(1)–S(2)
Heteroatom Chemistry DOI 10.1002/hc

Syntheses and Characterization of Organotin(IV) Complexes Derived from 2-Mercapto-1,3,4-thiadiazole
7
FIGURE 8 Molecular structure of complex 4.
FIGURE 6 Molecular structure of complex 3.
covalent of radii of tin and nitrogen (2.15 A◦) [25],
˚
concerning the distance of Sn(1)–N(2) [2.852(5) A],
is midway between the sum of the van der Waals
˚
and covalent radii of tin and nitrogen (3.75–2.15 A)
[25], and it can be regarded as a weak coordinative
bond. Thus, the environment of Sn1 increases to six-
coordinated distorted octahedral geometry.
CONCLUSIONS
Four organotin heterocyclic thiol complexes derived
from 2-mercapto-1,3,4-thiadiazole have been syn-
thesized and characterized. In our work, various
structures are found, including the mononuclear
structure, 1D zigzag infinite chain structure, ladder
structure, and 22-membered macrocycle structure
propagation via the intermolecular C H· · ·N hydro-
gen. These organotin structures reported in this pa-
per further enrich the organotin heterocyclic thiol
chemistry in the structural field.
FIGURE 7 Macrocycle structure of complex 3, propaga-
tion via intermolecular C H· · ·N hydrogen bond interactions
(three carbon atoms of the Sn butyl group were omitted for
clarity).
the ligand coordinating to the tin atom. This sit-
uation is similar to previously reported double O-
capped organo-oxotin cluster [30]. The four tin
atoms and four oxygen atoms are basically copla-
nar. Each of the ladders consists of four tin centers
held together by two μ3-oxygen atoms. According to
their different coordinative environments, the four
tin atoms can be divided into two types: Two tin
atoms Sn2 and Sn2A are each bonded to two μ3-
oxygen atoms and one nitrogen atom derived from
the ligand; other two tin atoms Sn1 and Sn1A are
bonded to two μ3-oxygen atoms. All of the tin atoms
are five-coordinated distorted trigonal bipyramidal
geometry. The bond lengthenlargethispage-12pt of
SUPPLEMENTARY DATA
Atomic coordinates, thermal parameters, and bond
lengths and angles for complexes 1, 2, 3 and 4
have been deposited in the Cambridge Crystallo-
graphic Data Center, CCDC nos. CCDC 857747,
857748, 857749 and 857750. Copies of this in-
formation may be obtained free of charge from
the Director, CCDC, 2 Union Road, Cambridge
CB2 1EZ, UK on request (fax: +44-1223-336-033;
E-mail: deposit@ccdc.cam.ac.uk or URL:http://
www.ccdc.cam.ac.uk).
˚
Sn(2)–N(1) is 2.290(4) A, approaching the sum of the
Heteroatom Chemistry DOI 10.1002/hc

8
Wang et al.
◦
˚
TABLE 4 Selected Bond Lengths (A) and Bond Angles ( ) for Complex 3
Bond lengths
Sn(1)–C(3)
Sn(1)–S(3)
2.130(5)
2.5506(11)
Sn(1)–C(9)
Sn(1)–S(2)
2.135(4)
2.5545(13)
Bond angles
C(3)–Sn(1)–C(9)
C(9)–Sn(1)–S(3)
C(9)–Sn(1)–S(2)
141.18(18)
104.02(14)
103.62(15)
C(3)–Sn(1)–S(3)
C(3)–Sn(1)–S(2)
S(3)–Sn(1)–S(2)
102.79(13)
106.15(14)
85.18(4)
◦
˚
TABLE 5 Selected Bond Lengths (A) and Bond Angles ( ) for Complex 4
Bond lengths
Sn(1)–O(1)#1
Sn(1)–C(4)
Sn(1)–O(2)
Sn(2)–O(1)
Sn(2)–C(6)
Sn(1)–N(2)
2.064(3)
2.111(5)
2.219(4)
2.015(3)
2.112(5)
2.852(5)
Sn(1)–C(3)
Sn(1)–O(1)
Sn(2)–N(1)
Sn(2)–C(5)
Sn(2)–O(2)#1
2.107(5)
2.122(3)
2.290(4)
2.109(6)
2.157(4)
Bond angles
O(1)#1–Sn(1)–C(3)
O(1)#1–Sn(1)–O(1)
O(1)#1–Sn(1)–O(2)
O(1)#1–Sn(1)–N(2)
O(2)–Sn(1)-N(2)
106.1(2)
C(3)–Sn(1)–C(4)
C(3)–Sn(1)–O(1)
O(1)–Sn(1)–O(2)
O(1)–Sn(1)–N(2)
O(1)–Sn(2)–O(2)#1
C(5)–Sn(2)–C(6)
145.0(3)
75.21(14)
72.56(13)
147.80(13)
139.64(13)
84.82(14)
99.03(19)
147.69(13)
72.62(12)
74.82(13)
133.7(3)
O(1)–Sn(2)-N(1)
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Heteroatom Chemistry DOI 10.1002/hc