Investigation on coordination modes of organotin(IV) complexes with 6-thiopurine and related ligands

Article abstract of DOI:10.1016/j.jorganchem.2004.12.026

The organotin(IV) complexes R₂Sn(tpu)₂ ? L [L = 2MeOH, R = Me (1); L = 0: R = n-Bu (2), Ph (3), PhCH₂ (4)], R ₃Sn(Hthpu) [R = Me (5), n-Bu (6), Ph (7), PhCH₂ (8)] and (R₂SnCl)₂ (

Full text of DOI:10.1016/j.jorganchem.2004.12.026

Journal of Organometallic Chemistry 690 (2005) 1560–1569
www.elsevier.com/locate/jorganchem
Investigation on coordination modes of organotin(IV)
complexes with 6-thiopurine and related ligands
a,b,
a
a
a
Chunlin Ma
*, Jiafeng Sun , Yang Shi , Rufen Zhang
a
Department of Chemistry, Liaocheng University, 34 Wenhua Road, Liaocheng 252059, PR China
b
Taishan University, Taian 271021, PR China
Received 5 November 2004; accepted 21 December 2004
Available online 12 January 2005
Abstract
The organotin(IV) complexes R2Sn(tpu)2 Æ L [L = 2MeOH, R = Me (1); L = 0: R = n-Bu (2), Ph (3), PhCH2 (4)], R3Sn(Hthpu)
[R = Me (5), n-Bu (6), Ph (7), PhCH2 (8)] and (R2SnCl)2 (dtpu) Æ L [L = H2O, R = Me (9); L = 0: R = n-Bu (10), Ph (11), PhCH2
(12)] have been synthesized, where tpu, Hthpu and dtpu are the anions of 6-thiopurine (Htpu), 2-thio-6-hydroxypurine (H2thpu)
1
and 2,6-dithiopurine (H2dtpu), respectively. All the complexes 1–12 have been characterized by elemental, IR, H, 13C and 119Sn
NMR spectra analyses. And complexes 1, 2, 7 and 9 have also been determined by X-ray crystallography, complexes 1 and 2
are both six-coordinated with R2Sn coordinated to the thiol/thione S and heterocyclic N atoms but the coordination modes differed.
As for complex 7 and 9, the geometries of Sn atoms are distorted trigonal bipyramidal. Moreover, the packing of complexes 1, 2, 7
and 9 are stabilized by the hydrogen bonding and weak interactions.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: 6-Thiopurine; Organotin(IV); Coordination modes
1. Introduction
from purine caught our attractions [4], for example, 6-
thiopurine (Htpu), 2-thio-6-hydroxypurine (H2thpu)
and 2,6-dithiopurine (H2dtpu) (see Scheme 1).
Organotin(IV) compounds are attracting more and
more attention for their potential industrial applications
and biological activities [1]. Recently, increasing investi-
gation on organotin(IV) complexes has been focused on
acquiring well-defined solid-state structures to learn the
nature of their versatile bonding modes [2], especially
that of some organotin(IV) derivatives from heterocyclic
thionates [3]. Heterocyclic thionates are ligands derived
from heterocyclic thiones that contain at least one
deprotonated heterocyclic thioamide group (N–C–S)À
and can act as monodentate, chelating and bridging li-
gands. Among them, due to the versatile coordination
modes and effective biological activities, derivatives
Htpu, which is an anticancer antimetabolite (inter
alia) proved to be clinically effective against human leu-
kemias [5]. The Htpu ligand is interesting also because of
it has multiple binding sites such as N1, N3, S6, N7 and
N9, when it coordinates to tin atom, the coordination
modes are certainly versatile (see Scheme 2). If coordina-
tion occurs through the S site, there may be two isomer-
ism between thiol and thione form (mode A and B) [6].
While if as a N,S-chelating ligand, two nitrogen atoms
(N1 and N7) will compete to involve the coordination
to the center tin atom. The final structure will depend
on the stability of the N1/S6 (mode C) or S6/N7 (mode
D) and different alkyl groups of organotin compounds
[6,7]. For instance, in Me3Sn(tpu), Htpu adopted
mode E to coordinate to tin atoms, and formed a poly-
meric trigonal bipyramidal structure [6]. While in
*
Corresponding author. Tel.: +86 635 825 8579/823 8121; fax: +86
538 671 5521.
E-mail address: macl@lctu.edu.cn (C. Ma).
0022-328X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.12.026

C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
1561
H2dtpu) products with only one chloride atom of
R2SnCl2 replaced.
Y2
Y1 Y2
SH
H2thpu SH OH
H2dtpu SH SH
N
6
N
5
Htpu
H
7
1
2
8
9
4
2.2. IR spectra
3
N
H
Y1
N
The IR spectra of organotin complexes 1–12 are sum-
marized in Table 1. The data show that the medium
absorption at 1150 cmÀ1 in free ligands due to the
C@S is absent in spectra of all complexes 1 and 3–12,
while new absorption appears 700–800 cmÀ1 region
which have been assignable to m(C–S) according to liter-
ature [3d], suggesting the coordinates of ligands involved
in these complexes are through sulfur atoms via thiolate
form. However, the two absorptions at 1224 and
782 cmÀ1 coexist in the spectrum of the complex 2,
which have been assigned to m(C@S) and m(C–S), respec-
tively, indicating that the two chelating ligand act as
thiol and thione forms, respectively. In the far-IR spec-
tra, the absorption in 305–312 cmÀ1 region for all com-
plexes 1–12, which is absent in the spectra of the free
ligands, is assigned to the m(Sn–S) and all the values
are located within the range for Sn–S vibration observed
in common organotin derivatives of thiolate (300–
400 cmÀ1) [10]. The m(Sn–Cl) absorption at about
290 cmÀ1 in complexes 9–12 is close to that found
in (S-dimethylchlorostannyl)-1-phenyl-5-thiotetrazole
(300 cmÀ1) [11], which suggests the incomplete substitu-
ent of chloride atoms of R2SnCl2. In organotin com-
pounds, the IR spectra can provide useful information
concerning the geometry of the SnCn moiety [12]. In
the case of our complexes, for both di- and triorgano-
tin(IV) derivatives, two bands were assigned to
asymmetric and symmetric Sn–C vibrations. Thus sug-
gesting non-linear SnC2 units for diorganotins and
non-planar SnC3 fragments for triorganotins,
respectively.
Scheme 1.
Bz3Sn(tpu)SnBz3OMe, Htpu adopted mode F to coordi-
nate to tin atoms, and displayed a binuclear structure
[3e]. As far as in n-Bu2Sn(tpu)2, Htpu adopted mode
D to coordinate to tin atom [6].
In our previous work, we have studied the coordina-
tion behavior of five- and six-membered thiol/thione
heterocycles to organotin(IV) [8,9]. As an extension of
this research program and in connection with our cur-
rent interest in the coordination chemistry of organo-
tin(IV) compounds with heterocyclic thionates, we
choose three fascinating ligands: Htpu, H2thpu and
H2dtpu. We synthesized
a series of complexes,
R2Sn(tpu)2 Æ L [L = 2MeOH, R = Me (1); L = 0: R = n-
Bu (2), Ph (3), PhCH2 (4)], R3Sn(Hthpu) [R = Me (5),
n-Bu (6), Ph (7), PhCH2 (8)] and (R2SnCl)2(dtpu) Æ L
[L = H2O, R = Me (9); L = 0: R = n-Bu (10), Ph (11),
PhCH2 (12)]. All the complexes 1–12 have been charac-
1
terized by elemental, IR, H, 13C and 119Sn NMR spec-
tra analyses. And complexes 1, 2, 7 and 9 have also been
determined by X-ray crystallography.
2. Results and discussion
2.1. Syntheses
The organotin(IV) derivatives were obtained by
reacting stoichiometric amounts of the thiopurine, so-
dium methoxide and corresponding organotin chlorides.
The syntheses procedure is given in Scheme 3.
2.3. NMR spectra
As shown in above Scheme, complexes 1–4 were
synthesized by using
1
The H, 13C and 119Sn NMR spectral data are col-
a
1:2:2 molar ratio of
lected in Table 2. The 1H NMR data show that the
chemical shifts of the phenyl group (Sn–C6H5) in com-
plexes 3, 7 and 11, 7.36–7.80 ppm, and those of methyl
or methylene connected directly with tin in other com-
plexes, 0.74–3.61 ppm, low frequency shift as compared
R2SnCl2:Htpu:MeONa. When using a 1:1:1 molar ratio
of R3SnCl:H2thpu:MeONa, complexes 5–8 were ob-
tained. It is worthy to note that despite using a 1:1:2
molar ratio of R2SnCl2:H2dtpu:MeONa in the synthe-
ses of complexes 9–12, we obtained 2:1 (R2SnCl2:
Sn
Sn
S
Sn
Sn
Sn
S
S
S
S
S
H
7
9
N
H
N
N
9
6
N
N
9
N
9
N 1
6
N
6
6
6
N 1
7
N 1
6
7
N 1
N 1
7
7
N 1
7
3
N
9
3
N
9
N
3
N
3
N
3
N
3
N
N
N
N
N
H
H
H
H
Sn
Sn
Sn
A
B
C
D
E
F
Scheme 2.

1562
C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
R
Sn
N
N
N
S
S
N
.
L
R
HN
N
N
NH
[L = 2M eOH, R = M e (1); L = 0: R = Ph (3), PhC H2 (4)]
R2SnCl 2
2MeONa
+ 2Htpu
+
R
S
Sn
R
N
N
.
L
N
S
N
N
H
N
HN
N
[L = 0: R = n-Bu (2)]
OH
R
N
N
+ H2thpu
Sn
R3SnCl
MeONa
+
R
N
N
S
H
R
[R = M e (5), n-Bu (6), Ph (7), PhC H2 (8)]
R
Cl
Sn
S
R
R
N
N
.
R2SnCl 2
+
2MeONa
+ H2dtpu
L
Sn
Cl
N
S
N
H
R
[L = H2O, R = M e (9); L = 0: R = n-Bu (10), Ph (11), PhCH2 (12)]
Scheme 3.
Table 1
Some relevant infrared spectral data (cmÀ1) for organotin(IV) complexes of Htpu, H2thpu and H2dtpu
Complex
m(C–S)
mas(Sn–C)
ms(Sn–C)
m(Sn–S)
Others
Me2Sn(tpu)2 Æ 2MeOH (1)
(n–Bu)2Sn(tpu)2 (2)
(Ph)2Sn(tpu)2 (3)
757
782
750
732
704
712
704
697
791
789
790
790
550
442
532
452
535
449
543
535
558
551
555
543
517
424
507
427
504
425
525
461
519
525
500
514
305
310
311
307
305
310
305
312
312
310
305
308
3427, m(O–H)
1224, m(C@S)
–
(PhCH2)2Sn(tpu)2 (4)
Me3Sn(Hthpu) (5)
–
3429, m(O–H)
3425, m(O–H)
3430, m(O–H)
3426, m(O–H)
3429, m(O–H); 289, m(Sn–Cl)
286, m(Sn–Cl)
285, m(Sn–Cl)
281, m(Sn–Cl)
(n–Bu)3Sn(Hthpu)2 (6)
Ph3Sn(Hthpu) (7)
(PhCH2)3Sn(Hthpu) (8)
(Me2SnCl)2(dtpu) Æ H2O (9)
(n–Bu2SnCl)2(dtpu) (10)
(Ph2SnCl)2(dtpu) (11)
[(PhCH2)2SnCl]2(dtpu) (12)
with those of their corresponding precursors. All these
data are similar to those cases appear in literature [13],
indicating coordination of the ligand to tin atom oc-
curred for all the complexes 1–12.
The structural changes occurring in ligand upon
deprotonation and coordination to the Sn atom should
be reflected by the changes in the 13C NMR spectra of
our complexes If the initial thione form of ligand
changes to the thiolate on complexation, C2 and/or C6
should be further low frequency in the spectra of all
complexes compared with those in free ligands, the
shielding effect of the C@N bond being greater than that
of the C@S bond [14]. As shown in Table 2, C6 atom of
complex 2 shows two signals (d 170.7, 160.5), one is sim-
ilar to that of free ligand (d 169.5) and the other is
shifted by 9 ppm to low frequency compared with it,
indicating that two tpu act as thiolate and thione forms,
respectively. Moreover, C2 and/or C6 atom signals of

C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
1563
complexes 1 and 3–12 are shifted by 5–15 ppm to low
frequency compared with those of free ligands, suggest-
ing the ligands involved in these complexes act as thio-
late form.
From the 13C NMR spectra, we can also obtain use-
ful information about the actual linkage isomerism of li-
gands. According to the literature, if the thiopurine
coordinate to tin atom by the mode D, the signal of
the C5 atom will high frequency shift compared with
that of free ligand [15]. For complexes 1, 3 and 4, the
C5 signals are located at d 127.3–127.8 region, much
close to that of free Htpu (d 128.4), suggesting no mode
D involved in these complexes. While, for the complex 2,
two signals for C5 appear at d 127.7 and 136.5. Together
with the signal of C4 (d 144.8 and 151.3), the informa-
tion indicates that N7 atoms in complex 2 exist in two
different environment, one is similar to that in free li-
gand and the other is consistent with that adopts coor-
dination mode D. Both the C5 and C4 signals of
complexes 9–12 (as shown in Table 2) are shifted by
10–20 ppm to high frequency compared with that of
H2dtpu. This fact means that complexes 9–12 all adopt
the chelating mode D. All of above analyses are con-
firmed by X-ray diffraction.
As reported in literatures [16], values of d(119Sn) in
the ranges À210 to À400, À90 to À190 and 200 to
À60 ppm have been associated with six-, five- and
four-coordinate tin centers, respectively. The d(119Sn)
values of 1–4 [68.3 (1), 50.8 (2), À82.1 (3) and 63.1 (4)]
are intermediate between those of four-coordinated
diorganotin dithiolates [d(119Sn) 122–144 ppm] and six-
coordinated diorganotin bis(dithiocarbamates) [e.g.,
Me2Sn(SCSNEt2)2, d(119Sn) À336 ppm] [17]. All these
revealed expanded coordination geometry about tin in
solution. The 119Sn NMR spectra of 5–8 show only
one sharp signal, and the d values found (119.4, 120.3,
À63.4 and 96.6 ppm, respectively) are consistent with a
tetrahedral and monomeric structure in solution. Be-
sides, the 119Sn NMR chemical shifts of 9–12 are in
accordance with those of five coordinate diorgano-
tin(IV) halides complexes involving halide or phosphine
ligands [18], as well as chelating S-donors and O-donors
complexes [19,20]. Thus, the d(119Sn) values of 9–12
[À77.9 (9), À72.3 (10), À84.8 (11) and À65.7 (12)] sug-
gest that the Sn–N interactions probably survive in solu-
tion and that five-coordinate species is maintained.
2.4. Description of crystal structures
2.4.1. Me2Sn(tpu)2 Æ 2MeOH (1)
The molecular structure of complex 1 is shown in Fig.
1, selected bond lengths and angles are given in Table 3.
There exists crystallographic twofold axe in the complex
1. Thus, two Sn–S and Sn–N bonds are identical, respec-
tively, due to the symmetric operation. The tin atom
establishes covalent bonds with the two thiolate sulfur

1564
C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
Fig. 1. Molecular structure of the complex 1.
Table 3
skew-trapezoidal bipyramidal with the two methyl car-
bons in bent axial positions and the plane being defined
by the two Sn–S covalent bonds and the two Sn–N sec-
ondary interactions. The C–Sn–C angle is 130.5(4)°. The
two sulfur atoms occupy cis-positions with the S–Sn–S
angle, 87.27(10)°.
It is worth to note that the component Me2Sn(tpu)2
crystallizes with two molecules of methanol and through
the hydrogen bonding between them the supramolecular
structure of complex 1 becomes a 2D network (Fig. 2).
The methanol molecules involve in two hydrogen bonds,
˚
Selected bond lengths (A) and bond angles (°) for 1
Sn(1)–C(6)
Sn(1)–C(7)
Sn(1)–S(1)
Sn(1)–N(3)
N(1)–C(1)
N(1)–C(5)
N(2)–C(1)
N(2)–C(2)
2.104(7)
2.109(7)
2.497(2)
2.718(6)
1.349(7)
1.377(7)
1.319(7)
1.372(6)
N(3)–C(4)
N(3)–C(3)
N(4)–C(5)
N(4)–C(4)
O(1)–C(8)
S(1)–C(3)
C(2)–C(5)
C(2)–C(3)
1.330(7)
1.337(6)
1.319(10)
1.329(6)
1.390(7)
1.733(6)
1.392(8)
1.408(8)
C(6)–Sn(1)–C(7)
C(6)–Sn(1)–S(1)
C(7)–Sn(1)–S(1)
C(6)–Sn(1)–S(1A)
C(7)–Sn(1)–S(1A)
130.5(4)
106.5(3)
S(1)–Sn(1)–S(1A)
C(6)–Sn(1)–N(3)
C(7)–Sn(1)–N(3)
S(1)–Sn(1)–N(3)
S(1A)–Sn(1)–N(3)
87.27(10)
85.05(13)
83.09(12)
60.67(14)
147.94(12)
108.73(19)
106.5(3)
108.73(19)
˚
acting as a donor (O(1)–H(1B)Á Á ÁN(2) 2.741(6) A, O(1)–
H(1B)–N(2) 164.13°) as well as an acceptor (N(1)–
˚
H(1A)Á Á ÁO(1) 2.724(6) A, N(1)–H(1A)–O(1) 171.77°).
atoms and weak connections with two heterocyclic
nitrogen atoms (N(3), N(3A)) of the ligand (mode C).
2.4.2. (n-Bu)2Sn(tpu)2 (2)
For complex 2, the asymmetric unit contains two
monomers A and B (see Fig. 3), which are crystallo-
graphically non-equivalent. The conformations of the
two independent molecules A and B are almost the
same, with only small differences in bond lengths and
bond angles (see Table 4). The geometry at tin atom in
the complex 2 is distorted octahedral with the two meth-
ylene carbons in axial positions and the equatorial plane
being defined by two S atoms and two N atoms. Two
Sn–S bonds and two Sn–N bonds form around each
tin atom but the two Sn–S bond lengths are much dis-
tinct and the same case occurs for Sn–N bond lengths.
˚
The Sn–S bond distances (2.497(2) A) are very close to
˚
the sum of the corresponding covalent radii (2.42 A)
[21], similar to the distances found in other Sn(IV) com-
plexes of the terazolethiolato with metal–sulfur primary
˚
bonds, viz. 2.474(3)–2.614(5) A [11,22]. The Sn–N bond
˚
lengths are markedly shorter [Sn(1)–N(3) 2.718(6) A]
than those reported in diorganotin derivatives of 1-phe-
˚
nyl-1H-tetrazole-5-thilato (2.975(5) [22c] and 2.947(4) A
[23]), all of which lie within the sum of their respective
˚
van der Walls radii (3.74 A) [24]. These information sug-
gests that the ligand Htpu adopts mode C to coordinate
tin atom.
˚
The shorter Sn–S bond (Sn(1)–S(1) 2.529(2) A for A
˚
and Sn(2)–S(3) 2.514(2) A for B) is close to the sum of
˚
the covalent radii of tin and sulfur atoms (2.42 A) [21],
Including the intramolecular tin–nitrogen interac-
tions, the geometry of center tin atom thus becomes
Fig. 2. Perspective view showing the 2D network of the complex 1.

C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
1565
Fig. 3. Molecular structure of the complex 2.
Table 4
Selected bond lengths (A) and bond angles (°) for 2
˚
while the longer one (Sn(1)–S(2) 3.123(2) A for A and
˚
Sn(2)–S(4) 3.128(2) A for B) is near to the sum of the
˚
van der Waals radii of the two atoms (4.0 A) [24]. Sim-
ilarly, the shorter and the longer Sn–N bond lengths
˚
Molecule A
Molecule B
Sn(1)–C(11)
Sn(1)–C(15)
Sn(1)–N(8)
Sn(1)–S(1)
Sn(1)–N(1)
Sn(1)–S(2)
N(1)–C(1)
N(1)–C(2)
N(2)–C(2)
N(2)–C(3)
N(3)–C(4)
N(3)–C(3)
N(4)–C(4)
N(4)–C(5)
N(5)–C(7)
N(5)–C(6)
N(6)–C(7)
N(6)–C(8)
N(7)–C(9)
N(7)–C(8)
N(8)–C(9)
N(8)–C(10)
S(1)–C(1)
S(2)–C(6)
2.117(8)
2.147(8)
2.196(5)
2.529(2)
2.725(5)
3.123(2)
1.336(8)
1.361(8)
1.290(8)
1.334(8)
1.308(8)
1.355(8)
1.342(8)
1.373(7)
1.327(8)
1.414(8)
1.322(8)
1.347(8)
1.316(8)
1.341(7)
1.336(8)
1.358(7)
1.732(6)
1.681(7)
Sn(2)–C(33)
Sn(2)–C(29)
Sn(2)–N(16)
Sn(2)–S(3)
2.095(9)
2.137(8)
2.209(5)
2.514(2)
2.660(5)
3.128(2)
1.328(8)
1.339(8)
1.331(7)
1.302(8)
1.320(8)
1.372(8)
1.341(8)
1.361(8)
1.295(9)
1.396(9)
1.335(9)
1.342(8)
1.308(8)
1.337(7)
1.328(8)
1.350(8)
1.740(6)
1.659(8)
˚
(Sn(1)–N(8) 2.196(5) A and Sn(1)–N(1) 2.725(5) A for
˚
˚
˚
A, Sn(2)–N(16) 2.209(5) A and Sn(2)–N(9) 2.660(5) A
for B) approach to the sum of the covalent radii
Sn(2)–N(9)
Sn(2)–S(4)
˚
(2.15 A) and the van der Waals radii of tin and nitrogen
˚
atoms (3.74 A) [24], respectively. Furthermore, there are
N(9)–C(20)
N(9)–C(19)
N(10)–C(21)
N(10)–C(20)
N(11)–C(22)
N(11)–C(21)
N(12)–C(22)
N(12)–C(23)
N(13)–C(25)
N(13)–C(24)
N(14)–C(25)
N(14)–C(26)
N(15)–C(27)
N(15)–C(26)
N(16)–C(27)
N(16)–C(28)
S(3)–C(19)
differences between two C–S bonds (S(2)–C(6)
˚
˚
1.681(7) A and S(1)–C(1) 1.732(6) A for A, S(4)–C(24)
˚
1.659(8) A and S(3)–C(19) 1.740(6) A for B). The shorter
˚
˚
C–S bond length is near to that in thioureas (1.681 A),
suggesting its role as C@S double bond. While the longer
lies between the average value for the double C@S bond
˚
in thioureas (1.681 A) and the single C–S bond in the C–
˚
S–Me fragment (1.789 A) [25], so that it can be regarded
as C–S single bond and also suggesting that it has some
double-bond character. All these remarkable differences
in Sn–S, Sn–N and C–S bond lengths reveal that the
thiol and thione forms may be concurrent in the Htpu
when it reacts with n-Bu2SnCl2. Thus we can conclude
that two S,N-chelating ligand asymmetrically coordi-
nate to the center tin atom, different from that of com-
plex 1, which adopts modes C and D simultaneously.
And the conclusion is complementary to Barbieriꢀs pre-
diction according to the data of infrared and Mo¨ssbauer
spectroscopy [9].
S(4)–C(24)
C(11)–Sn(1)–C(15)
C(11)–Sn(1)–N(8)
C(15)–Sn(1)–N(8)
C(11)–Sn(1)–S(1)
C(15)–Sn(1)–S(1)
N(8)–Sn(1)–S(1)
C(11)–Sn(1)–N(1)
C(15)–Sn(1)–N(1)
N(8)–Sn(1)–N(1)
S(1)–Sn(1)–N(1)
C(11)–Sn(1)–S(2)
C(15)–Sn(1)–S(2)
N(8)–Sn(1)–S(2)
S(1)–Sn(1)–S(2)
N(1)–Sn(1)–S(2)
143.7(3)
103.1(3)
104.4(3)
102.0(2)
103.9(2)
84.40(14)
84.3(3)
C(33)–Sn(2)–C(29)
C(33)–Sn(2)–N(16)
C(29)–Sn(2)–N(16)
C(33)–Sn(2)–S(3)
C(29)–Sn(2)–S(3)
N(16)–Sn(2)–S(3)
C(33)–Sn(2)–N(9)
C(29)–Sn(2)–N(9)
N(16)–Sn(2)–N(9)
S(3)–Sn(2)–N(9)
C(33)–Sn(2)–S(4)
C(29)–Sn(2)–S(4)
N(16)–Sn(2)–S(4)
S(3)–Sn(2)–S(4)
139.3(4)
106.5(3)
105.0(3)
103.3(3)
104.0(3)
86.06(14)
85.6(3)
In addition, intermolecular hydrogen bonding (N(7)–
˚
H(7)Á Á ÁN(4) 2.766(7) A, N(7)–H(7)–N(4) 164.87° for A
87.0(3)
81.6(3)
˚
144.29(17)
59.93(12)
84.8(2)
147.27(18)
61.38(12)
82.6(3)
and N(15)–H(15)Á Á ÁN(12) 2.867(7) A, N(15)–H(15)–
N(12) 164.35° for B) is recognized, which associates
the discrete molecule into a dimer. Besides, both the
hydrogen bonding and intermolecular non-bonded
NÁ Á ÁN interactions are noted in the complex 2, which
help the construction of the 2D network (Fig. 4). The
82.0(2)
83.5(3)
71.31(14)
155.69(5)
144.38(11)
71.65(14)
157.68(5)
140.94(12)
N(9)–Sn(2)–S(4)

1566
C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
Table 5
Selected bond lengths (A) and bond angles (°) for 7
˚
Sn(1)–C(18)
Sn(1)–C(12)
Sn(1)–C(6)
Sn(1)–S(1)
Sn(1)–N(1)
N(1)–C(2)
N(1)–C(1)
N(2)–C(2)
N(2)–C(3)
2.127(6)
2.134(6)
2.165(6)
2.4661(17)
2.653(5)
1.341(7)
1.343(7)
1.332(7)
1.345(7)
N(3)–C(3)
N(3)–C(4)
N(4)–C(4)
N(4)–C(5)
O(1)–C(1)
S(1)–C(2)
C(1)–C(5)
C(3)–C(5)
1.350(7)
1.368(8)
1.311(8)
1.383(8)
1.343(7)
1.740(6)
1.398(8)
1.375(8)
C(18)–Sn(1)–C(12)
C(18)–Sn(1)–C(6)
C(12)–Sn(1)–C(6)
C(18)–Sn(1)–S(1)
C(12)–Sn(1)–S(1)
115.3(2)
106.7(2)
C(6)–Sn(1)–S(1)
C(18)–Sn(1)–N(1)
C(12)–Sn(1)–N(1)
C(6)–Sn(1)–N(1)
S(1)–Sn(1)–N(1)
99.43(16)
78.38(19)
88.6(2)
106.6(2)
115.86(17)
111.11(17)
159.03(19)
60.92(10)
˚
3.74 A) [24], and approaches to the Sn–N length in the
complex 1. The C–S bond distance (C(2)–S(1)
˚
1.740(6) A) is similar to the longer C–S bond in complex
Fig. 4. Perspective view showing the 2D network of the complex 2.
2, also suggesting that the single C–S bond has some
double-bond character in the deprotonated H2thpu.
Including the Sn(1)–N(1) interaction, the geometry at
Sn(1) atom becomes distorted cis-trigonal bipyramidal
with the axial–tin–axial angle N(1)–Sn(1)–C(6) of
159.03(19).
˚
non-bonded NÁ Á ÁN distances (N(2)Á Á ÁN(13) 2.772(8) A
˚
and N(5)Á Á ÁN(10) 2.794(8) A) are shorter than the sum
of the van der Waals radii of nitrogen and nitrogen
˚
(3.08 A) [21].
There recognized two kind of hydrogen bonding in
the crystal of complex 7. One exists between the N(3)–
2.4.3. Ph3Sn(Hthpu) (7)
The molecular structure of complex 7 is shown in
Fig. 5, selected bond lengths and angles are collected
in Table 5. As expected, when the Htpu was replaced
by the H2thpu ligand, we found that the bonding is
through the deprotonated SH rather than the OH group
and the ligand adopts N1/S2 mode to coordinate to tin
H(3) and the N(2) derive from a neighboring molecule
˚
N(3)–H(3)–N(2)
(N(3)–H(3)Á Á ÁN(2)
2.804(7) A,
166.45°). And the other exists between O(1)–H(1) and
the N(4) of
a
third molecule (O(1)–H(1)Á Á ÁN(4)
˚
2.883(7) A, O(1)–H(1)–N(4) 143.39°). Thus the supra-
molecular structure of complex 7 is constructed as a
1D polymer (Fig. 6).
˚
atom. The bond length of Sn(1)–S(1) (2.4661(17) A) ap-
proaches to the sum of the covalent radii of tin and sul-
˚
fur (2.42 A) [21]. The bond distance of Sn(1)–N(1)
2.4.4. (Me2SnCl)2(dtpu) Æ H2O (9)
The molecular structure of complex 9 is shown in
Fig. 7, selected bond lengths and angles are given in Ta-
˚
(2.653(5) A) is midway between the sums of the van
der Waals and covalent radii of tin and nitrogen (2.15,
Fig. 5. Molecular structure of the complex 7.

C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
1567
Fig. 6. Perspective view showing the 1D polymer of the complex 7.
Fig. 8. Perspective view showing the 2D network of the complex 9.
˚
˚
(Sn(1)–S(1) 2.524(2) A and Sn(2)–S(2) 2.484(2) A) ap-
proach the sum of the covalent radii of Sn and S
˚
(2.42 A) [21]. Concerning the Sn–N bond lengths,
˚
though Sn(1)–N(1) bond length (2.597(5) A) is little
˚
longer than that of Sn(2)–N(2) (2.428(5) A), they are
both midway between the sums of the van der Waals
˚
and covalent radii of tin and nitrogen (2.15–3.74 A)
˚
[24]. Two Sn–Cl bonds (Sn(1)–Cl(1) 2.430(2) A and
˚
Sn(2)–Cl(2) 2.434(3) A) are typical Sn–Cl bond lengths
found in chloroorganotin(IV) complexes in general
[12,25]. Thus, the geometry at tin atoms become dis-
torted trigonal bipyramidal with C(6), C(6A) and S(1)
atoms for Sn(1), C(7), C(7A) and S(2) atoms for Sn(2)
occupying the equatorial plane. And the axial angle
Cl(1)–Sn(1)–N(1) and Cl(2)–Sn(2)–N(2) are 164.19(12)
and 152.57(14), respectively.
Fig. 7. Molecular structure of the complex 9.
Table 6
The supramolecular structure of complex 9 is a 2D
network (Fig. 8) linked by all kinds of weak interactions
such as SnÁ Á ÁCl, SnÁ Á ÁS, SnÁ Á ÁN and N–HÁ Á ÁCl. The
˚
Selected bond lengths (A) and bond angles (°) for 9
Sn(1)–C(6)
Sn(1)–Cl(1)
Sn(1)–S(1)
Sn(1)–N(1)
Sn(2)–C(7)
Sn(2)–Cl(2)
Sn(2)–S(2)
Sn(2)–N(2)
N(1)–C(5)
N(1)–C(1)
2.101(5)
2.430(2)
2.524(2)
2.597(5)
2.091(7)
2.434(3)
2.484(2)
2.428(5)
1.304(9)
1.374(8)
N(2)–C(2)
N(2)–C(3)
N(3)–C(3)
N(3)–C(4)
N(4)–C(5)
N(4)–C(4)
S(1)–C(2)
S(2)–C(3)
C(1)–C(4)
C(1)–C(2)
1.348(8)
1.375(8)
1.322(8)
1.365(8)
1.329(9)
1.352(9)
1.709(7)
1.730(7)
1.391(9)
1.392(9)
˚
SnÁ Á ÁCl distance is 3.580(8) A, shorter than the sum of
˚
the van der Waalsꢀ radii of Sn and Cl (3.85 A) [24].
˚
˚
The SnÁ Á ÁS and SnÁ Á ÁN are 3.675(7) A and 2.907(8) A,
respectively. For the hydrogen bond, the N(4)–
˚
H(4)Á Á ÁCl(1) and N(4)–H(4)–Cl(1) are 3.278(7) A and
143.16°, respectively. All of them benefit the construc-
tion of the 2D network.
Besides, it should be noted that the component
(Me2SnCl)2(dtpu) crystallizes with one molecule of
water that acts as an acceptor in the hydrogen
C(6A)–Sn(1)–C(6)
C(6)–Sn(1)–Cl(1)
C(6)–Sn(1)–S(1)
Cl(1)–Sn(1)–S(1)
C(6)–Sn(1)–N(1)
Cl(1)–Sn(1)–N(1)
S(1)–Sn(1)–N(1)
147.2(4)
C(7A)–Sn(2)–C(7)
C(7)–Sn(2)–Cl(2)
C(7)–Sn(2)–S(2)
Cl(2)–Sn(2)–S(2)
C(7)–Sn(2)–N(2)
Cl(2)–Sn(2)–N(2)
S(2)–Sn(2)–N(2)
131.5(4)
101.9(2)
110.9(2)
89.40(9)
88.9(2)
99.70(17)
103.85(17)
85.33(8)
˚
bond (N(4)–H(4)Á Á ÁO(1) 2.933(6) A, N(4)–H(4)–O(1)
84.24(16)
164.19(12)
78.86(13)
126.05°).
152.57(14)
63.16(14)
3. Experimental details
ble 6. There exists crystallographic symmetry in the
complex 1. Thus, two Sn–C bonds are identical, respec-
tively. As shown in Fig. 7, when we choose the H2dtpu
ligand to react with Me2SnCl2, the complex 9 is ob-
tained. Which is a binuclear and the H2dtpu adopts
N1/S2 and S6/N7 modes. Both of the Sn–S bond lengths
3.1. Materials and measurements
Trimethyltin chloride, tri-n-butyltin chloride, triphe-
nyltin chloride, dimethyltin dichloride, di-n-butyltin
dichloride, diphenyltin dichloride, and all of the

1568
C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
thiopurine were commercially available, and they were
used without further purification. Tribenzyltin chloride
and dibenzyltin dichloride were prepared by a standard
method reported in the literature [26]. The melting
points were obtained with Kofler micro melting point
apparatus and are uncorrected. Infrared-spectra were
recorded on a Nicolet-460 spectrophotometer using
KBr discs and sodium chloride optics. 1H, 13C and
119Sn NMR spectra were recorded on a Bruker
AMX-300 spectrometer operating at 300, 75.3 and
93.28 MHz, respectively. The TMS and Me4 Sn were
used as internal standards. The chemical shifts were gi-
ven in ppm in CDCl3 or CD3Cl–D2O solvent. Elemen-
3.2. Synthesis
The general route of synthesis is shown in the follow-
ing. The reaction was carried out under nitrogen atmo-
sphere with use of standard Schlenk technique.
Thiopurine (Htpu, H2thpu or H2dtpu) ligand and the
sodium methoxide were added to the solution of metha-
nol, the mixture was stirred for 10 min, and then added
organotin chlorides to the mixture, continuing the reac-
tion about 12 h at 40 °C. After cooling down to room
temperature, filtered it. The solvent of the filtrate was
gradually removed by evaporation under vacuum until
solid product was obtained. The solid was then recrys-
tallized from methanol and the elemental analyses of
all products are shown in Table 7.
tal analyses were performed with
apparatus.
a
PE-2400II
Table 7
Physical and analytical data for organotin(IV) complexes of Htpu, H2thpu and H2dtpu
Complexa,b
m.p. (°C)
Yield (%)
Analysis Found (Calc.) (%)
C
H
N
Me2Sn(tpu)2 Æ 2MeOH (1)
(n-Bu)2Sn(tpu)2 (2)
(Ph)2Sn(tpu)2 (3)
142–144
268–270
168–171
123–124
122–124
75–77
73
78
69
81
75
65
84
87
70
74
85
71
32.44(32.64)
40.33(40.39)
46.09(45.93)
47.96(47.78)
29.23(29.03)
44.78(44.66)
53.35(53.41)
54.47(54.26)
19.05(19.01)
34.94(35.08)
43.72(43.59)
46.14(46.35)
3.74(3.91)
4.54(4.52)
2.85(2.80)
3.41(3.34)
3.68(3.65)
6.65(6.61)
3.41(3.51)
3.75(3.79)
2.68(2.84)
5.33(5.33)
2.56(2.78)
3.61(3.54)
21.71(21.75)
21.03(20.93)
19.38(19.48)
18.45(18.57)
17.09(16.93)
12.33(12.25)
10.79(10.83)
10.40(10.55)
10.05(9.85)
7.64(7.79)
(PhCH2)2Sn(tpu)2 (4)
Me3Sn(Hthpu) (5)
(n-Bu)3Sn(Hthpu)2 (6)
Ph3Sn(Hthpu) (7)
212–215
142–143
116–118
148–150
140–143
124–125
(PhCH2)3Sn(Hthpu) (8)
(Me2SnCl)2(dtpu) Æ H2O (9)
(n-Bu2SnCl)2(dtpu) (10)
(Ph2SnCl)2(dtpu) (11)
[(PhCH2)2SnCl]2(dtpu) (12)
7.15(7.01)
6.67(6.55)
a
All complexes are pale yellow.
Solvent of recrystallization: methanol.
b
Table 8
Crystal data and structure refinement parameters for 1, 2, 7 and 9
1
2
7
9
Empirical formula
M
C
14H20N8O2S2Sn
C18H24N8S2Sn
535.26
298(2)
C23H18N4OSSn
517.16
298(2)
C9H16Cl2N4OS2Sn2
568.66
298(2)
515.19
293(2)
T (K)
Crystal system
Space group
Orthorhombic
Cmc21
27.28(3)
7.383(8)
10.597(12)
90
Monoclinic
P21/c
Triclinic
ꢀ
Orthorhombic
Cmca
P1
˚
a (A)
13.589(8)
23.021(14)
15.498(9)
90
9.431(3)
9.487(3)
15.866(5)
88.172(5)
78.842(6)
74.973(5)
1344.9(8)
2
10.827(8)
26.875(18)
16.320(11)
90
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
90
90
103.308(9)
90
90
90
3
˚
V (A )
2134(4)
4
1.418
4718(5)
8
1.281
4749(6)
8
2.504
Z
l (mmÀ1
)
1.045
7123
Reflections collected
Independent reflections
Rint
Goodness-of-fit on F2
R1, wR2 [I > 2r(I)]
R1, wR2 (all data)
4270
1601
23,856
8116
11,483
2121
4661
0.0399
0.0403
0.985
0.0537
0.941
0.0357
1.026
0.928
0.0544, 0.1267
0.0800, 0.1371
0.0274, 0.0606
0.0301, 0.0618
0.0491, 0.1067
0.1054, 0.1323
0.0351, 0.0941
0.0480, 0.1033

C. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 1560–1569
1569
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´
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Crystals were mounted in Lindemann capillaries un-
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lected on a Bruker SMART CCD 1000 diffractometer
with graphite monochromated Mo Ka radiation
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(k = 0.71073 A). A semi-empirical absorption correction
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was applied to the data. The structure was solved by di-
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Crystal data and experimental details of the structure
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4. Supplementary material
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Press, London, 1970.
Crystallographic data (excluding structure factors)
for the structure reported in this paper (1, 2, 7 and 9)
have been deposited with the Cambridge Crystallo-
graphic Data Center as Supplementary Publication
Nos. CCDC-220163, 222016, 223775, 223782. Copies
of the data can be obtained free of charge on application
to the Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (fax: +44 1223 336033; e-mail: depos-
it@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
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Acknowledgments
´ˇ
ˇ
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We thank the National Natural Science Foundation
of China (20271025) and the Natural Science Founda-
tion of Shandong Province for financial support.
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