Synthesis and structural characterizations of diorganotin(IV) complexes with 2-pyrazinecarboxylic acid

Article abstract of DOI:10.1016/j.jorganchem.2005.11.062

Two types of diorganotin(IV) complexes {[R₂Sn(O ₂CC₄H₃N₂)]₂O} ₂ (R = n-octyl 1, 2-ClC₆H₄CH₂ 3, 2-FC₆H₄CH₂ 5, 4-F

Full text of DOI:10.1016/j.jorganchem.2005.11.062

Journal of Organometallic Chemistry 691 (2006) 1235–1241
www.elsevier.com/locate/jorganchem
Synthesis and structural characterizations of diorganotin(IV)
complexes with 2-pyrazinecarboxylic acid
*
Han Dong Yin , Gang Li, Zhong Jun Gao, Hao Long Xu
Department of Chemistry, Liaocheng University, Liaocheng 252059, China
Received 21 September 2005; received in revised form 24 November 2005; accepted 25 November 2005
Available online 4 January 2006
Abstract
Two types of diorganotin(IV) complexes {[R2Sn(O2CC4H3N2)]2O}2 (R = n-octyl 1, 2-ClC6H4CH2 3, 2-FC6H4CH2 5, 4-FC6H4CH2 7)
and R2Sn(O2CC4H3N2)2 (R = n-octyl 2, 2-ClC6H4CH2 4, 2-FC6H4CH2 6, 4-FC6H4CH2 8) were prepared by reactions of diorganotin
oxide with 2-pyrazinecarboxylic acid. The complexes 1–8 are characterized by elemental analysis, IR and NMR (1H, 13C, 119Sn) spec-
troscopies. The complexes {[(n-C8H17)2Sn(O2CC4H3N2)]2O}2 (1) and (n-C8H17)2Sn(O2CC4H3N2)2 (2) are also determined by X-ray
single crystal diffraction, which reveal that the endo-cyclic tin atom of complex 1, is seven-coordinate, and the exo-cyclic tin atom is
hexa-coordinated geometry, while the complex 2 is seven-coordinated geometry. The nitrogen atom of the aromatic ring participates
in the interactions with the Sn atom.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Diorganotin oxide; 2-Pyrazinecarboxylic acid; Synthesis; Crystal structure
1. Introduction
ment that contains a central planar Sn2O2 four-membered
ring. When a 1:2 ratio is used, a diorganotin dicarboxy-
late is formed.
The environmental and biological chemistry of organo-
tin(IV) carboxylates have been the subjects of interest for
some time due to their increasingly widespread use in
industry and agriculture [1–5]. In particular, a few diorg-
anotin(IV) derivatives have been shown to exhibit in vitro
antitumour properties against a wide panel of tumoral cell
lines of human origin. In general, the biochemical activity
of organotin carboxylates is influenced greatly by the
structure of the molecule and the coordination number
of the tin atoms [6–8]. Recent review on structures of
diorganotin carboxylates has demonstrated that when a
1:1 (tin/ligand) ratio is used, five types of structure
adopted in the crystalline state. A characteristic feature
of these complexes in the solid state is their dimerization
that results in the so-called ladder or staircase arrange-
Our current interest focuses on how the hetero-atoms
(N, O or S) of the carboxylic acids influence the coordina-
tion mode and further help the self-assemble of these mol-
ecules [9–11]. Based on the above considerations, we have
investigated a series of reactions of diorganotin oxide with
2-pyrazinecarboxylic acid. This ligand is interesting
because of its potential multiple bidentate coordination
possibilities. As exhibited in Scheme 1, at least seven bond-
ing modes between this ligand and tin are conceivable
although nobody has investigated its actual coordination
mode until now [10]. With 1:1 ratio (tin/ligand), we have
obtained four ladder complexes of the type {[R2Sn-
(O2CC4H3N2)]2O}2 (R = n-octyl 1, 2-ClC6H4CH2 3,
2-FC6H4CH2 5, 4-FC6H4CH2 7). With 1:2 ratio, another
four complexes were obtained and the general formula is
R2Sn(O2CC4H3N2)2 (R = n-octyl 2, 2-ClC6H4CH2 4,
2-FC6H4CH2 6, 4-FC6H4CH2 8).
*
Corresponding author. Tel.:/fax: +86 6358239121.
E-mail address: handongyin@sohu.com (H.D. Yin).
0022-328X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.11.062

1236
H.D. Yin et al. / Journal of Organometallic Chemistry 691 (2006) 1235–1241
144.20, 141.71 (C4H3N2–),174.22 (COO). 119Sn NMR
Sn
Sn
O
N
Sn
(CDCl3, ppm): d À380.5, À250.6.
Sn
O
N
O
N
O
N
O
N
O
O
O
N
N
2.2.2. Synthesis of {[(2-ClC6H4CH2)2Sn-
(O2CC4H3N2)]2O}2 (3)
Yield: 54%. m.p. 199–201 °C. Anal Calc. for
C76H60Cl8N8O10Sn4: C, 45.55; H, 3.02; N, 5.59. Found:
C, 45.56; H, 2.99; N, 5.57%. IR (KBr, cmÀ1): mas(COO),
1671, 1648; ms(COO), 1383, 1377; m(Sn–C), 569; m(Sn–O),
N
A
C
B
D
Sn
Sn
O
N
N
O
O
N
Sn
1
O
474; m(Sn–O–Sn), 619, m(Sn–N), 452. H NMR (CDCl3,
O
N
O
N
E
ppm): d 3.04 (t, 8H, JSn–H = 80 Hz, SnCH2), 3.22 (t, 8H,
JSn–H = 86 Hz, SnCH2), 6.59–6.72 (m, 32H, Ph–H), 7.75–
8.88 (m, 12H, pyrazine–H). 13C NMR (CDCl3, ppm): d
31.58 (CH2Ar, 1J(119Sn–13C), 615 Hz), 32.54 (CH2Ar,
1J(119Sn–13C), 844 Hz), 151.63, 150.68, 136.10, 128.47,
125.21, 125.35, 122.73, 122.59 (Ar–C), 147.01, 146.41,
143.85, 141.56 (C4H3N2–), 170.26 (COO). 119Sn NMR
(CDCl3, ppm): d À344.7, À230.1.
N
G
F
Scheme 1.
2. Experimental
2.1. Materials and measurements
2.2.3. Synthesis of {[2-FC6H4CH2]2Sn(O2CC4H3N2)2O}2
(5)
All the reactions were carried out under nitrogen atmo-
sphere. Di-n-octyltin oxide and 2-pyrazinecarboxylic acid
were used as received. The (ArCH2)2SnO were prepared
by the reported method [12]. The melting points were
obtained with Kofler micro-melting points apparatus and
were uncorrected. Infrared spectra were recorded on a
Nicole-460 spectrophotometer using KBr discs. 1H, 13C
and 119Sn NMR spectra were recorded on a Mercury Plus-
400 NMR spectrometer. Chemical shifts are given in ppm
relative to Me4Si and Me4Sn in CDCl3 solvent. Elemental
analyses were performed on PE-2400-II elemental analyzer.
Yield: 56%. m.p. 190–192 °C. Anal Calc. for
C76H60F8N8O10Sn : C, 48.76; H, 3.23; N, 5.98. Found:
4
C, 48.71; H, 3.26; N, 5.95%. IR (KBr, cmÀ1): mas(COO),
1637, 1604; ms(COO), 1428, 1379; m(Sn–C), 571; m(Sn–O),
1
477; m(Sn–O–Sn), 628, m(Sn–N), 446. H NMR (CDCl3,
ppm): d 2.93 (t, 8H, JSn–H = 80 Hz, SnCH2), 3.21 (t, 8H,
JSn–H = 88 Hz, SnCH2), 6.62–6.74 (m, 32H, Ph–H), 7.74–
8.87 (m, 12H, pyrazine–H). 13C NMR (CDCl3, ppm): d
31.16 (CH2Ar, 1J(119Sn–13C), 613 Hz), 33.74 (CH2Ar,
1J(119Sn–13C), 853 Hz), 151.73, 148.56, 137.45, 129.65,
127.55, 127.21, 116.13, 115.52 (Ar–C), 147.01, 146.41,
143.85, 141.56 (C4H3N2–), 173.85 (COO). 119Sn NMR
(CDCl3, ppm): d À373.6, À248.7.
2.2. Synthesis of {[R2Sn(O2CC4H3N2)]2O}2 (R = n-octyl
1, 2-ClC6H4CH2 3, 2-FC6H4CH2 5, 4-FC6H4CH2 7)
The diorganotin oxide (2.0 mmol) and the 2-pyrazine-
carboxylic acid (2.0 mmol) were dissolved in dry benzene
(30 ml) and stirred at reflux for 7 h (for complexes 3, 5
and 7 stirred 14 h). After cooling to room temperature,
the solvent was evaporated under vacuum. The crude
adduct was recrystallized from dichloromethane–hexane
to give colorless crystals.
2.2.4. Synthesis of {[(4-FC6H4CH)2Sn-
(O2CC4H3N2)]2O}2 (7)
Yield: 51%. m.p. 195–196 °C. Anal. Calc. for
C76H60F8N8O10Sn : C, 48.76; H, 3.23; N, 5.98. Found:
4
C, 48.74; H, 3.28; N, 5.94%. IR (KBr, cmÀ1): mas(COO),
1655, 1620; ms(COO), 1439, 1379; m(Sn–C), 571; m(Sn–O),
1
471; m(Sn–O–Sn), 617, m(Sn–N), 447. H NMR (CDCl3,
ppm): d 2.92 (t, 8H, JSn–H = 80 Hz, SnCH2), 3.22 (t, 8H,
JSn–H = 88 Hz, SnCH2), 6.62–6.74 (m, 32H, Ph–H), 7.74–
8.87 (m, 12H, pyrazine–H). 13C NMR (CDCl3, ppm): d
31.46 (CH2Ar, 1J(119Sn–13C), 607 Hz), 33.27 (CH2Ar,
1J(119Sn–13C), 857 Hz), 137.34, 131.15, 129.31, 128.74,
123.79, 122.83 (Ar–C), 148.64, 147.25, 142.74, 141.64
(C4H3N2–), 172.55 (COO). 119Sn NMR (CDCl3, ppm): d
À359.4, À225.5.
2.2.1. {[(n-C8H17)2Sn(O2CC4H3N2)]2O}2 (1)
Yield: 81%. m.p. 103–104 °C. Anal. Calc. for
C84H148N8O10Sn4: C, 52.96; H, 7.83; N, 5.88. Found: C,
52.92; H, 7.80; N, 5.91%. IR (KBr, cmÀ1): mas(COO),
1663, 1639; ms(COO), 1400, 1374; m(–(CH2)n–), 725; m(Sn–
C), 577; m(Sn–O), 479; m(Sn–O–Sn), 620; m(Sn–N), 443.
1H NMR (CDCl3, ppm): d 0.80 (t, 24H, CH3), 1.34–1.67
(m, 112H, SnCH2CH2CH2CH2CH2CH2CH2), 7.71–8.85
(m, 12H, pyrazine–H). 13C NMR (CDCl3, ppm): d 33.85
(aCH2, 1J(119Sn–13C), 618 Hz), 34.02 (aCH2, 1J(119Sn–
13C), 780 Hz), 31.87 (bCH2), 32.21 (bCH2), 29.64 (cCH2),
29.39 (cCH2), 29.20 (dCH2), 29.14 (dCH2), 27.36 (eCH2),
25.95 (eCH2), 25.34 (fCH2), 22.58, (fCH2), 18.41 (gCH2),
18.30 (gCH2), 14.07 (CH3), 13.94 (CH3), 147.64, 147.13,
2.3. Synthesis of R2Sn(O2CC4H3N2)2 (R = n-octyl 2,
2-ClC6H4CH2 4, 2-FC6H4CH2 6, 4-FC6H4CH2 8)
The diorganotin oxide (2.0 mmol) and the 2-pyrazine-
carboxylic acid (4.0 mmol) were dissolved in dry benzene
(30 ml) and stirred at reflux for 7 h (for complexes 4, 6

H.D. Yin et al. / Journal of Organometallic Chemistry 691 (2006) 1235–1241
1237
Table 1
and 8 stirred 14 h). After cooling to room temperature, the
solvent was evaporated under vacuum. The crude adduct
was recrystallized from dichloromethane–hexane to give
colorless crystals.
Crystal data collection and structure refinement parameters for complexes
1 and 2
1
2
Empirical formula
M
C84H148N8O10Sn4 C26H40N4O4Sn
1904.86
298(2)
591.31
298(2)
2.3.1. (n-C8H17)2Sn(O2CC4H3N2)2 (2)
T (K)
Yield: 79%; m.p. 179–181 °C. Anal. Calc. for
C26H40N4O4Sn: C, 52.80; H, 6.82; N, 9.47. Found: C,
52.78; H, 6.83; N, 9.45%. IR (KBr, cmÀ1): mas(COO),
1646, 1598; ms(COO), 1415, 1347; m(–(CH2)n–) 723; m(Sn–
Crystal system
Space group
Triclinic
Orthorhombic
Pbca
ꢀ
P1
˚
a (A)
11.942(6)
21.513(10)
21.520(10)
104.830(7)
4969(4)
2
12.123(4)
18.819(6)
26.004(8)
90
5932(3)
8
˚
b (A)
˚
1
c (A)
C), 536; m(Sn–O), 485; m(Sn–N), 467. H NMR (CDCl3,
b (°)
ppm):
d 0.82 (t, 24H, CH3), 1.27–1.70 (m, 28H,
3
˚
V (A )
SnCH2CH2CH2CH2CH2CH2CH2), 7.73–8.87 (m, 6H, pyr-
azine–H). 13C NMR (CDCl3, ppm): d 34.54 (aCH2,
1J(119Sn–13C), 615 Hz), 32.21 (bCH2), 29.74 (cCH2),
29.19 (dCH2), 26.36 (eCH2), 23.17 (fCH2), 18.36 (gCH2),
13.94 (CH3), 148.01, 147.23, 144.86, 142.17 (C4H3N2–),
174.55 (COO). 119Sn NMR (CDCl3, ppm): d À432.5.
Z
Calculated density (Mg/m3)
1.273
1.324
F(000)
1976
2448
l (mmÀ1
)
1.046
0.896
Scan range h (°)
Reflections collected
Unique data
Date/restraints/parameters
Maximum/minimum transmission 0.6620, 0.5920
GOF
1.92–25.03
25512
2.15–25.02
28636
17026
5094
17026, 214, 796
5094, 68, 316
0.7940, 0.6680
1.072
2.3.2. (2-ClC6H4CH2)2Sn(O2CC4H3N2)2 (4)
0.999
Yield: 49%; m.p. 212–214 °C. Anal. Calc. for
C24H18Cl2N4O4Sn: C, 46.79; H, 2.95; N, 9.09. Found: C,
46.76; H, 2.99; N, 9.07%. IR (KBr, cmÀ1): mas(COO),
1642, 1615; ms(COO), 1435, 1388; m(Sn–C), 532; m(Sn–O),
482; m(Sn–N), 468. 1H NMR (CDCl3, ppm): d 2.96 (t,
4H, JSn–H = 96 Hz, SnCH2), 6.63–6.71 (m, 8H, Ph–H),
7.70–8.90 (m, 6H, pyrazine–H). 13C NMR (CDCl3, ppm):
d 33.58 (CH2Ar, 1J(119Sn–13C), 889 Hz), 138.18, 135.42,
131.98, 121.92, 117.85, 115.43 (Ar–C), 150.16, 147.36,
145.74, 143.65 (C4H3N2–), 172.23 (COO). 119Sn NMR
(CDCl3, ppm): d À412.7.
R1, wR2 [I > 2r(I)]
R1, wR2 (all data)
Largest difference peak,
0.0793, 0.1334
0.2233, 0.1759
1.138, À0.478
0.0680, 0.1588
0.1205, 0.2098
1.263, À2.310
À3
˚
hole (e A
)
2.4. X-ray crystallographic studies
X-ray crystallographic data for complexes 1 and 2 were
collected on a Bruker smart-1000 CCD diffractometer
using Mo Ka radiations (0.71073 A). The structures were
solved by direct method and difference Fourier map using
SHELXL-97 program, and refined by full-matrix least-
squares on F2. All non-hydrogen atoms were refined aniso-
tropically. Hydrogen atoms were located at calculated
positions and refined isotropically. Further details are
given in Table 1.
˚
2.3.3. (2-FC6H4CH2)2Sn(O2CC4H3N2)2 (6)
Yield: 56%; m.p. 218–220 °C. Anal. Calc. for
C24H18F2N4O4Sn: C, 49.43; H, 3.11; N, 9.61. Found: C,
49.40; H, 3.14; N, 9.58%. IR (KBr, cmÀ1): mas(COO),
1630, 1588; ms(COO), 1412, 1331; m(Sn–C), 551; m(Sn–O),
492; m(Sn–N), 464. 1H NMR (CDCl3, ppm): d 2.13 (t,
4H, JSn–H = 97 Hz, SnCH2), 6.73–6.82 (m, 8H, Ph–H),
7.81–8.99 (m, 6H, pyrazine–H). 13C NMR (CDCl3, ppm):
d 34.58 (CH2Ar, 1J(119Sn–13C), 889 Hz), 138.98, 130.15,
129.01, 124.13, 118.05, 116.43 (Ar–C), 147.01, 146.41,
143.85, 141.56 (C4H3N2–), 172.86 (COO). 119Sn NMR
(CDCl3, ppm): d À441.8.
3. Results and discussion
3.1. Spectroscopic studies
3.1.1. IR spectra
The infrared spectra of the diorganotin(IV) carbonxy-
lates are listed above. The Dm(mas(CO2)–ms(CO2)) value
can be used to determine the type of bonding between
metal and carboxyl group [13,14]. It is generally believed
that the difference in Dm between asymmetric masym(CO2)
and symmetric msym(CO2) absorption frequencies below
200 cmÀ1 for the bidentate carboxylate moiety, but greater
than 200 cmÀ1 for the monodentate carboxylate moiety
[15–18]. For complexes 1, 3, 5 and 7 the values of Dm are
between 210 and 300 cmÀ1 and this strongly indicates that
these complexes adopt the monodentate carboxylate struc-
ture. In complexes 2, 4, 6 and 8, the magnitudes of
Dm1[mas(CO2)1–ms(CO2)1] and Dm2[mas(CO2)2–ms(CO2)2] are
254–299 and 174–188 cmÀ1 which indicate the presence of
2.3.4. (4-FC6H4CH2)2Sn(O2CC4H3N2)2 (8)
Yield: 56%; m.p. 215–218 °C. Anal. Calc. for
C24H18F2N4O4Sn: C, 49.43; H, 3.11; N, 9.61. Found: C,
49.41; H, 3.15; N, 9.57%. IR (KBr, cmÀ1): mas(COO),
1645, 1611; ms(COO), 1423, 1350; m(Sn–C), 558; m(Sn–O),
484; m(Sn–N), 459. 1H NMR (CDCl3, ppm): d 2.16 (t,
4H, JSn–H = 85 Hz, SnCH2), 6.75–6.86 (m, 8H, Ph–H),
7.84–9.05 (m, 6H, pyrazine–H). 13C NMR (CDCl3, ppm):
d 35.41 (CH2Ar, 1J(119Sn–13C), 889 Hz), 135.34, 126.55,
125.98, 116.43 (Ar–C), 147.01, 146.41, 143.85, 141.56
(C4H3N2–), 173.47 (COO). 119Sn NMR (CDCl3, ppm): d
À450.3.

1238
H.D. Yin et al. / Journal of Organometallic Chemistry 691 (2006) 1235–1241
bidentate and monodentate carboxylate groups in these
complexes. A strong absorption appears at 471–492 cmÀ1
in the respective spectra of the complexes 1–8, which is
absent in the spectra of the free ligand. This is assigned
to the Sn–O stretching mode of vibration. The observation
of two Sn–C absorption bands in the 532–577 cmÀ1 region
reveals a non-linear trans configuration of the C–Sn–C
moiety. New vibrations, which appear in the 443–
468 cmÀ1, are attributed to Sn–N bonds. For complexes
1, 3, 5 and 7, a strong band near 620 cmÀ1, which is
absence in the other four complexes, is assigned to m(Sn–
O–Sn), indicating a Sn–O–Sn bridged structure. These
assignments are also confirmed by the X-ray diffraction
studies of complexes 1 and 2.
Although at least two different types of carboxyl groups
are present, only single resonances are observed for the
COO group in the 13C spectra. The possible reason is that
either accidental magnetic equivalence of the carbonyl car-
bon atoms or the separations between the two sets of reso-
nance are too small to be resolved. The 13C NMR data for
the complexes 1, 3, 5 and 7 are consistent with a dimeric
1
tetraorganostannoxane structure. The JSnC values for 1,
3, 5 and 7 are 590–626 and 831–870 Hz, are similar to that
of the dimeric organotin complex {[nBu2Sn(2-Py)]2O}2
[21,22].
The 119Sn NMR of complexes 1, 3, 5 and 7 showed two
well separated resonances, characteristic of the tetraorgan-
odistannoxane structure [23]. The low- and high-field reso-
nances observed for these complexes are attributed to the
exo-cyclic and endo-cyclic tin atoms, respectively [23]. Sin-
gle resonances at the regions À225.5 to À250.6 and À344.7
to À230.5 ppm in the 119Sn NMR spectra of complexes
suggest that the tin atoms exhibit hexa-coordination [23].
The 119Sn chemical shift values in complexes 2, 4, 6 and
8 are found to be in the range of À412.7 to À450.3 ppm.
The appearance of chemical shift values in this region
indicates seven-coordination environment [23] around the
central tin atoms in these complexes.
3.1.2. NMR spectroscopic
The 1H NMR spectra show the expected integration and
peak multiplicities. In the spectra of the free ligand, single
resonance are observed at 11.46 ppm, which is absent in the
spectra of the complexes indicating the replacement of the
carboxylic acid proton by a diorganotin moiety on complex
formation. The 1H NMR of complexes 3, 5, 7 show that the
chemical shifts of the protons of methylene bound to tin
atom (ArCH2Sn) exhibit two signals at the region 2.91–
3.30 ppm as triplets and indicates that there are two differ-
ent types of tin atoms, which is also indicated by tin
3.2. Crystal structure of {[(n-C8H17)2Sn(O2CC4H3N2)]2-
O}2 (1)
(
119Sn)–hydrogen coupling. The coupling constant JSn–H
are equal 76–80 and 82–89 Hz, which would be in agree-
ment with the decrease of the s-character of the C(Bz)-Sn
bonds on going from 5- to 6-coordination [19,20].
In the crystal of complex 1, the asymmetric unit contains
two independent molecules that are practically superimpos-
Fig. 1. Molecular structure of complex 1.

H.D. Yin et al. / Journal of Organometallic Chemistry 691 (2006) 1235–1241
1239
able. In fact, a computer fitting of molecules A and B
shows only a very marginal difference in the bond lengths
and angles. One of the two molecules is represented in
Fig. 1, the chemical structure diagram is represented
in Scheme 2, selected bond lengths and angles are listed
in Table 2. There are significant intra- and inter-molecular
contracts in the crystal lattice. As observed for the related
structure [2,17,22], the core geometry of the molecule con-
sists of a centrosymmetric planar four-membered Sn2O2
ring with two additional (n-C8H17)2Sn(O2CC4H3N2) unit
attached to each bridging oxygen atom, with the result that
these oxygen atoms are three coordinate. The two crystal-
lographically unique 2-pyrazinecarboxylic ligands coordi-
nate in different ways. The ligand contains the O(1) and
O(2) atoms bridging two tin atoms via the O(1) atom,
˚
Sn(1)–O(1) 2.412(7) A and Sn(2)–O(1) 2.450(6). Although
˚
the O(2) oxygen is 3.615 A from the Sn(1) atom, a distance
O
N
N
is slightly less than the sum of the van der Waal’s radii for
C
˚
Sn and O of 3.74 A [20], it is not indicative of a significant
R
N
O
N
bonding interaction. The C–O bond distance which associ-
ates with the oxygen atombridging the two tin atoms of
R
R
C
O
Sn
Sn
˚
1.294(11) A is significantly longer than the other C–O bond
O
˚
distance of 1.211(14) A that suggests a partial localization
O
R
R
of p-electron density in the C(1)–O(1) bond. The nitrogen
O
R
O
atom from the 2-pyrazine ring of this ligand a even close
Sn
Sn
R
˚
contact with Sn(2) at 2.920(9) A, and another nitrogen
O
R
C
O
atom from the 2-pyrazine ring of another ligand makes a
N
N
C
˚
even closer contact to Sn(1) at 2.730(10) A, which are sig-
O
nificantly less than the sum of the van der Waal’s radii
N
N
˚
for Sn and N of 3.74 A [17] and should be considered as
Scheme 2.
a bonding interaction. The O(3) of the second ligand in
Table 2
˚
Selected bond lengths (A) and angles (°) for complex 1 and 2
˚
Bond lengths (A)
Bond angles (°)
Bond angles (°)
Complex 1
Sn(1)–O(5)
Sn(1)–C(19)
Sn(1)–C(11)
Sn(1)–O(3)
Sn(1)–O(1)
Sn(1)–N(3)
Sn(2)–O(5)
Sn(2)–C(35)
Sn(2)–C(27)
Sn(2)–O(5A)
Sn(2)–O(1)
Sn(2)–N(1)
Sn(2)–O(3A)
2.040(6)
2.049(13)
2.104(13)
2.190(7)
2.412(7)
2.730(10)
2.032(6)
2.052(13)
2.076(14)
2.108(6)
2.450(6)
2.920(9)
2.798(8)
C(19)–Sn(1)–C(11)
O(5)–Sn(1)–O(3)
C(19)–Sn(1)–O(3)
C(11)–Sn(1)–O(3)
O(5)–Sn(1)–O(1)
C(19)–Sn(1)–O(1)
C(11)–Sn(1)–O(1)
O(3)–Sn(1)–O(1)
O(5)–Sn(1)–N(3)
C(19)–Sn(1)–N(3)
C(11)–Sn(1)–N(3)
O(3)–Sn(1)–N(3)
O(1)–Sn(1)–N(3)
O(5)–Sn(2)–C(35)
O(5)–Sn(2)–C(27)
C(35)–Sn(2)–C(27)
O(5)–Sn(2)–O(5A)
C(35)–Sn(2)–O(5A)
C(27)–Sn(2)–O(5A)
134.8(6)
75.6(3)
102.7(4)
109.4(5)
69.8(2)
86.7(4)
84.7(5)
145.3(2)
140.0(3)
83.0(5)
83.0(5)
64.4(3)
150.2(3)
111.7(4)
107.3(4)
140.5(5)
71.9(3)
98.3(3)
99.6(4)
O(5)–Sn(2)–O(1)
C(35)–Sn(2)–O(1)
C(27)–Sn(2)–O(1)
O(5A)–Sn(2)–O(1)
O(5)–Sn(2)–N(1)
C(35)–Sn(2)–N(1)
C(27)–Sn(2)–N(1)
O(5A)–Sn(2)–N(1)
O(1)–Sn(2)–N(1)
O(5)–Sn(2)–O(3A)
C(35)–Sn(2)–O(3A)
C(27)–Sn(2)–O(3A)
O(5A)–Sn(2)–O(3A)
O(1)–Sn(2)–O(3A)
N(1)–Sn(2)–O(3A)
Sn(1)–O(1)–Sn(2)
Sn(2)–O(5)–Sn(1)
Sn(2)–O(5)–Sn(2A)
Sn(1)–O(5)–Sn(2A)
69.1(2)
95.0(4)
92.8(4)
141.0(2)
127.7(3)
76.5(4)
74.8(4)
160.3(3)
58.7(3)
85.65(19)
58.9(3)
119.3(3)
139.56(19)
36.11(17)
53.4(2)
96.0(2)
125.0(3)
108.1(3)
126.9(3)
Complex 2
Sn(1)–C(11)
Sn(1)–C(19)
Sn(1)–O(1)
Sn(1)–O(3)
Sn(1)–O(4A)
Sn(1)–N(1)
Sn(1)–N(3A)
2.044(11)
2.121(9)
2.195(6)
2.317(6)
2.352(6)
2.429(7)
2.684(8)
C(11)–Sn(1)–C(19)
C(11)–Sn(1)–O(1)
C(19)–Sn(1)–O(1)
C(11)–Sn(1)–O(3)
C(19)–Sn(1)–O(3)
O(1)–Sn(1)–O(3)
C(11)–Sn(1)–O(4A)
C(19)–Sn(1)–O(4A)
O(1)–Sn(1)–O(4A)
O(3)–Sn(1)–O(4A)
C(11)–Sn(1)–N(1)
169.6(6)
92.0(5)
95.9(3)
88.5(4)
86.0(3)
81.8(2)
92.6(4)
85.1(3)
143.2(2)
134.8(2)
95.9(5)
C(19)–Sn(1)–N(1)
O(1)–Sn(1)–N(1)
O(3)–Sn(1)–N(1)
O(4A)–Sn(1)–N(1)
C(11)–Sn(1)–N(3A)
C(19)–Sn(1)–N(3A)
O(1)–Sn(1)–N(3A)
O(3)–Sn(1)–N(3A)
O(4A)–Sn(1)–N(3A)
N(1)–Sn(1)–N(3A)
93.2(4)
70.1(2)
151.7(2)
73.1(2)
82.3(5)
87.6(3)
152.2(2)
70.9(2)
64.5(2)
137.4(2)

1240
H.D. Yin et al. / Journal of Organometallic Chemistry 691 (2006) 1235–1241
{[(C8H17)2Sn(O2CN2H3C4)]2O}2 forms a strong bond to
Sn(1), 2.190(7) and 2.796(4) A from Sn(2A). Atom O(4) does
coordination sphere can be thought of as a distorted
octahedron.
˚
not make any significant contacts with the tin atoms. As
˚
for the second ligand, the C(6)–O(4) bond at 1.120(12) A
3.3. Crystal structure of (n-C8H17)2Sn(O2CC4H3N2)2 (2)
˚
is shorter than the C(6)–O(3) bond at 1.265(11) A. A weak
SnÁ Á ÁN interactions exist between the Sn atom and the
adjacent nitrogen atom, thereby forming a chelate with a
five-membered ring.
The crystal structure of complex 2 is shown in Fig. 2 and
the one-dimensional chain structure is illustrated in Fig. 3.
A structural line diagram is shown in Scheme 3. Selected
bond distances and bond angles are listed in Table 2. Com-
plex 2 contains a seven-coordinated tin atom and has a
pentagonal bipyramidal environment with the C(11) and
C(19) atoms occupying the axial sites and the axial–Sn–
axial angle, C(11)–Sn(1)–C(19) of 169.6(2)°. The tin atom
lies on a crystallographic twofold structure. Atoms Sn(1),
O(1), O(3), N(3A), O(4A), N(1) are completely coplanar
with the tin atom lying in the plane. The sum of angles
between the tin atom and the equatorial atoms is 360.4°,
consistent with the ideal value of 360°. In the structure,
two carbons atoms and two nitrogen atoms of 2-pyrazine-
carboxylic acid and an oxygen atom of the other 2-pyrazin-
ecarboxylic acid are covalently linked to the tin. The Sn–N
The endocyclic tin atom, Sn(2), is seven-coordinate to a
first approximation and exists in a distorted pentagonal
bipyramidal environment, with the two nOctyl groups
and the centrosymmetrically related bridging oxygen atom
defining an approximate pentagonal plane. The apical posi-
tion is occupied by C(27) and C(35) atom from the ligand.
The C(27)–Sn–C(35), is 140.5(5)°. The exocyclic tin atom,
Sn(1), forms four short bonds; a longer bond to O(5) is a
weak interaction. The geometry is highly distorted, the
˚
bond length (Sn(1)–N(1) 2.429(7) A and Sn(1)–N(4)#1,
n
˚
2.553(4) A) is longer than those in Bu2Sn(OOCC5H4N–
˚
2)2(H2O) (2.2522(6) A) [24,25], but much shorter than the
sum of the vander Waals radii of Sn and N, 3.74 A
[25,26]. The bond Sn(1)–O(4A) 2.352(6) A also approaches
the sum of the covalent radii of Sn and O (2.13 A) [26].
˚
˚
˚
These carboxylate groups are bidentate and use both oxy-
gen atoms to bridge between two tin atoms, thus the com-
plex becomes a one-dimensional chain polymer as shown in
N
O
C
N
N
R
R
O
Sn
O
N
Sn
O
C
O
C
N
R
N
O
R
O
N
C
O
N
Fig. 2. Molecular structure of complex 2.
Scheme 3.
Fig. 3. One-dimensional chain work of complex 2.

H.D. Yin et al. / Journal of Organometallic Chemistry 691 (2006) 1235–1241
n
1241
[7] J. Otera, T. Yano, R. Owawara, Organometallics 5 (1986) 1167.
Fig. 3. This is not the same as Bu2Sn(O2CN2H3C4)2 [27]
which forms a three-dimensional hydrogen bonded net-
work by hydrogen bonds.
[8] J.A. Zubita, J.J. Zukerman, Inorg. Chem. 24 (1987) 251.
[9] G. Atassi, Rev. Si, Ge, Sn, Pb Cpds 8 (1985) 21;
G.K. Sandhu, R. Gupta, S.S. Sandhu, R.V. Parish, Polyhedron 4
(1985) 81.
4. Supplementary material
[10] C.L. Ma, Y.F. Han, R.F. Zhang, D.Q. Wang, J. Chem. Soc., Dalton
Trans. (2004) 1832.
[11] S.G. Teoh, S.H. Ang, E.S. Looi, C.A. Keok, S.B. Teo, J.P. Declercq,
J. Organomet. Chem. 523 (1996) 75.
[12] H.D. Yin, Q.B. Wang, S.C. Xue, J. Organomet. Chem. 690 (2005)
831.
[13] (a) K. Sisido, Y. Takeda, Z. Kinugawa, J. Am. Chem. Soc. 82 (1960)
434;
(b) Q.L. Xie, X.H. Xu, D.K. Zhang, Acta Chim. Sinica 50 (1992)
508.
[14] G.K. Sandhu, N. Sharma, J. Organomet. Chem. 371 (1989) 31.
[15] V. Chandrasekhar, V. Bhaskar, A. Steiner, S. Zacchini, Organomet-
allics 21 (2002) 4528.
Crystallographic data for complexes 1 and 2 have been
deposited at the Cambridge Crystallographic Data Center
as supplementary publication numbers CCDC 284268
and 284269, respectively. The Director, CCDC, 12, Union
Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336033;
e-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).
Acknowledgements
[16] K.C.K. Swamy, M.A. Said, S. Nagabrahmanandachari, D.M. Pooj-
ary, J. Chem. Soc., Dalton Trans. (1998) 1645.
[17] X.N. Fang, X.Q. Song, Q.L. Xie, J. Organomet. Chem. 619 (2001)
43.
[18] H.D. Yin, C.H. Wang, Q.J. Xing, Polyhedron 23 (2004) 1805.
[19] S.P. Narula, S.K. Bharadwaj, Y. Sharda, D.C. Povey, G.W. Smith,
J. Organomet. Chem. 430 (1992) 167.
Authors acknowledge the financial support of the Shan-
dong Province Science Foundation, and the State Key Lab-
oratory of Crystal Materials, Shandong University, PR
China.
[20] C.S. Parulekar, V.K. Jain, T.K. Das, A.R. Gupta, J. Organomet.
Chem. 372 (1989) 193.
References
[21] D. Dakternieks, A. Duthie, D.R. Smyth, C.P.D. Stapleton, E.R.T.
Tiekink, Organometallics 22 (2003) 4599.
[22] H.D. Yin, C.H. Wang, C.L. Ma, D.Q. Wang, J. Organomet. Chem.
689 (2004) 246.
[23] T.S.B. Baul, S. Dhar, S.M. Pyke, E.R.T. Tiekink, E. Rivarola, R.
Butcher, F.E. Smith, J. Organomet. Chem. 633 (2001) 7.
[24] C.L. Ma, H.D. Yin, C.H. Wang, Y. Wang, Chin. J. Chem. 20 (2002)
1608.
[1] H.D. Yin, C.H. Wang, Y. Wang, C.L. Ma, J.X. Sao, J.H. Zhang,
Acta Chim. Sinica 60 (2002) 143.
[2] S.P. Narula, S. Kaur, R. Shankar, S.K. Bharadwaj, R.K. Chadha, J.
Organomet. Chem. 506 (1996) 181.
[3] S.B.B. Tushar, S.S. Keisham, H. Michal, J. Robert, L. Anthony,
Q.S. Xue, Z. Alejandra, E. George, Appl. Organomet. Chem. 19
(2005) 935.
[25] A. Bondi, J. Phys. Chem. 68 (1964) 441.
[26] C.L. Ma, Y.F. Han, R.F. Zhang, J. Organomet. Chem. 689 (2004)
1675.
[27] R. Kapoor, A. Gupta, P. Kapoor, P. Venugopalan, Appl. Organo-
met. Chem. 17 (2003) 600.
[4] M. Gielen, Appl. Organomet. Chem. 16 (2002) 481.
[5] S.B.B. Tushar, M. Cheerfulman, W. Rudolph, B. Monique, H.
Michal, J. Robert, L. Anthony, J. Organomet. Chem. 690 (2005) 3080.
[6] K.C. Molloy, T.G. Purcell, E. Hahn, H. Schumann, J.J. Zuckerman,
Organometallics 5 (1986) 85.