Self-assembly of triorganotin(IV) or diorganotin(IV) moieties and 2-methylpyrazine-5-acid: Syntheses, characterizations and crystal structures of monomeric, polymeric or tetranuclear macrocyclic compounds

Article abstract of DOI:10.1016/j.jorganchem.2006.10.061

A series of diorganotin(IV) and triorganotin(IV) compounds of the type [R₂Sn(pca)₂ClSnR₃]₂ (R{double bond, long}PhCH₂ 1, 2-ClC₆H₄CH₂ 2, 2-FC₆H₄CH₂ 3, 4-FC₆H₄CH₂ 4, 4-CNC₆H₄CH₂ 5, 4-ClC₆H₄CH₂ 6, 2,4-Cl₂C₆H₃CH₂ 7; Hpca{double bond, long}2-methylpyrazine-5-acid), [(ⁿBu)₃Sn(pca)]_∞ 8, [(CH₃)₂Cl₂Sn(pca)Sn(CH₃)₂(pca)]_∞ 9, {[(ⁿBu)₂Sn(pca)]₂O}₂ 10 and {[Ph₂Sn(pca)]₃O₂[Ph₂Sn(OCH₃)]} 11 have been obtained by reactions of 2-methylpyrazine-5-acid with triorganotin(IV) chloride, diorganotin(IV) dichloride, and diorganotin(IV) oxide. All compounds were characterized by elemental, IR, and NMR spectra analyses. The crystal structure of compounds 1, 8-11 were determined by X-ray single crystal diffraction, which revealed that compound 1 was tetranuclear macrocyclic structures with seven-coordinate and five-coordinate tin atoms, compounds 8 and 9 were polymeric chain structures with five-coordinate and seven-coordinate tin atoms, compounds 10 and 11 were monomeric structures with six-coordinate and five-coordinate tin atoms.

Full text of DOI:10.1016/j.jorganchem.2006.10.061

Journal of Organometallic Chemistry 692 (2007) 1010–1019
www.elsevier.com/locate/jorganchem
Self-assembly of triorganotin(IV) or diorganotin(IV) moieties and
2-methylpyrazine-5-acid: Syntheses, characterizations and
crystal structures of monomeric, polymeric or tetranuclear
macrocyclic compounds
*
Han Dong Yin , Fa Hui Li, Lin Wei Li, Gang Li
Department of Chemistry, Liaocheng University, Liaocheng 252059, China
Received 2 June 2006; received in revised form 20 October 2006; accepted 31 October 2006
Available online 7 November 2006
Abstract
A series of diorganotin(IV) and triorganotin(IV) compounds of the type [R2Sn(pca)2ClSnR3]2 (R@PhCH2 1, 2-ClC6H4CH2 2, 2-
FC6H4CH2 3, 4-FC6H4CH2 4, 4-CNC6H4CH2 5, 4-ClC6H4CH2 6, 2,4-Cl2C6H3CH2 7; Hpca@2-methylpyrazine-5-acid), [(nBu)3Sn(pca)]
1
8, [(CH3)2Cl2Sn(pca)Sn(CH3)2(pca)] 9, {[(nBu)2Sn(pca)]2O}2 10 and {[Ph2Sn(pca)]3O2[Ph2Sn(OCH3)]} 11 have been obtained by reac-
1
tions of 2-methylpyrazine-5-acid with triorganotin(IV) chloride, diorganotin(IV) dichloride, and diorganotin(IV) oxide. All compounds
were characterized by elemental, IR, and NMR spectra analyses. The crystal structure of compounds 1, 8–11 were determined by X-ray
single crystal diffraction, which revealed that compound 1 was tetranuclear macrocyclic structures with seven-coordinate and five-coor-
dinate tin atoms, compounds 8 and 9 were polymeric chain structures with five-coordinate and seven-coordinate tin atoms, compounds
10 and 11 were monomeric structures with six-coordinate and five-coordinate tin atoms.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Organotin(IV) compounds; 2-Methylpyrazine-5-acid; Synthesis; Crystal structure
1. Introduction
with nitrogen atoms, yielding products characterized by
Sn–N bonds [4]. This fact has led to considerable effort
being devoted to characterizing model compounds
obtained from the ligands which have other donor atoms
or groups. In previous work, we have reported on the
chemical, structural, spectroscopic properties of a series
of similar organotin(IV) compounds, characterized by dif-
ferent coordinating properties [5]. As an extension of this
research program and in connection with our current inter-
est in the coordination chemistry of organotin compounds
with heterocyclic ligands, we choose another fascinating
ligand: 2-methylpyrazine-5-acid (Hpca). This ligand is
interesting because of its potential multiple coordinate pos-
sibilities. As exhibited in Scheme 1, at least three bonding
modes between this ligand and tin are conceivable. The
above considerations stirred our interest in some detailed
syntheses, and structure patterns for diorganotin deriva-
tives of the ligand. Interestingly, we obtained a series of
Metal-directed self-assembly of organic ligands and
metal ions or organometallic substances with various
intriguing topologies have been extensively studied [1,2].
An important objective is also the synthesis of new higher
soluble metal compounds useful for testing the distinctive
reactivity patterns of the multimetallic systems. In recent
years organotin(IV) derivatives have received much atten-
tion, both in academic and applied research, because of
the ability of the tin to afford stable bonds with carbons
as well as with heteroatoms: a wide range of compounds
have been reported in organic synthesis and catalysis [3].
Especially, organotin compounds react with the ligands
*
Corresponding author. Tel.: +86 6358239121; fax: +86 6358239121/
8121.
E-mail address: handongyin@sohu.com (H.D. Yin).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.10.061

H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
1011
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.
Scheme 1.
2.2. Synthesis of the complex
diorganotin(IV) and triorganotin(IV) compounds by reac-
tion of diorganotin(IV) dichloride or triorganotin(IV) chlo-
ride with 2-methylpyrazine-5-acid in the presence of
sodium ethoxide. When using a 1:1:1 molar ratio of
RySnCl:Hpca:EtONa (R@PhCH2 1; 2-ClC6H4CH2 2, 2-
FC6H4CH2 3, 4-FC6H4CH2 4, 4-CNC6H4CH2 5, 4-
ClC6H4CH2 6, 2,4-Cl2C6H3CH2 7, y = 3), we obtained
seven tetranuclear macrocyclic compounds 1–7 of the type
[R2Sn(pca)2ClSnR3]2. Although also with a 1:1:1 ratio,
another two polymeric compounds 8 and 9 are obtained
The reactions 1–9 are carried out under a nitrogen atmo-
sphere. 2-Methylpyrazine-5-acid (2.0 mmol) was added to
the solution of benzene (20 ml) of triorganotin(IV) chloride
(or diorganotin(IV) dichloride) (2.0 mmol) in a Schlenk
flask and stirred for 0.5 h. After the sodium ethoxide
(2.0 mmol) was added to the reactor, the reaction mixture
was stirred for 24 h at 50 ꢁC and then filtered. The solvent
is gradually removed by evaporation under vacuum until a
solid product is obtained. The solid is then recrystallized
from methanol to give colorless crystals. The synthesis pro-
cedures are shown in Scheme 2, similar to our previous
studies [7,8]. The reaction 10 and 11 is of 2-Me-pyrazine-
and the general formula are [(nBu)3Sn(pca)] 8 (R@Bu,
1
y = 3) and [(CH3)2Cl2Sn(pca)Sn(CH3)2(pca)] 9 (R@CH3,
1
y = 2). When using a 1:1 molar ratio of R2SnO:Hpca
(R@Bu 10, Ph 11), we obtained two monomeric com-
pounds {[(nBu)2Sn(pca)]2O}2 10 and {[Ph2Sn(pca)]3O2-
[Ph2Sn(OCH3)]} 11. Determinations by elemental, IR,
and NMR spectra analyses of all the compounds are given
and except for compounds 2–7, the others are also charac-
terized by X-ray crystallography diffraction analyses.
n
5-Acid (2.0 mmol) with Bu2SnO (or Ph2SnO) (2.0 mmol)
in refluxing benzene and methyl (60 ml), which afford air-
stable solid complexes. The solid is then recrystallized from
methanol to give colorless crystals. The synthesis proce-
dures are shown in Scheme 2.
2.2.1. [(PhCH2)2Sn(pca)2ClSn(PhCH2)3]2 Æ 0.5CH3OH 1
The reaction is carried out under a nitrogen atmosphere.
2-Methylpyrazine-5-acid (0.276 g, 2.0 mmol) was added to
the solution of dry benzene (20 ml) of (PhCH2)3SnCl
(0.855 g, 2.0 mmol) in a Schlenk flask and stirred for
0.5 h. After the sodium ethoxide (0.136 g, 2.0 mmol) was
added to the reactor, the reaction mixture was stirred for
12 h at 50 ꢁC and then filtered. The solvent is gradually
removed by evaporation under vacuum until a solid prod-
uct is obtained. The solid is then recrystallized from meth-
anol and the colorless crystal compound 1 is formed. Yield:
2. Experimental
2.1. Materials and measurements
All the reactions were carried out under nitrogen atmo-
n
n
sphere. Bu3SnCl, (CH3)2SnCl2, Bu2SnO, Ph2SnO, and 2-
methylpyrazine-5-acid were used as received. The series of
triorganotin(IV) chloride (for 1–7) were prepared by the
reported method [6]. The melting points were obtained
with Kofler micro-melting points apparatus and were
uncorrected. Infrared spectra were recorded on a Nicole-
68%. Mp 116–117 ꢁC. Anal. Calc. for C94.50H88Cl2N8O8.50
-
(1)
(2)
R SnClL RH
R SnCl
H-L
H-L
+
+
2
3
MeOH
[R2SnL2ClSnR3]2
nCH3OH
(1)+(2)
EtONa
NaCl
R SnCl
R SnL
EtOH+
+
3
+
3
(R = PhCH 1, 2-ClC H CH 2, 2-FC H CH 3, 4-FC H CH 4,
4-CNC6H4CH2 5, 4-ClC6H4CH2 6,
2
6
4
2
6
4
2
6
4
2
)
n = 0, 0.5
2,4-Cl2C6H3CH2 7; L=Hpca = 2-Me-pyrazine-5-Acid;
[nBu3SnL]x
xEtONa
8
xnBu3Cl+xH-L
xEtOH
+
2EtONa
2NaCl
R2SnL2 +2 EtOH
+
2L
R2SnCl2
+
[R2Cl2SnLSnR2L]
{[nBu2SnL]2O}2
R=CH3
R2SnCl2
+
9
R2SnL2
∞
C6H6
C6H6
4nBu2SnO
10
+
4H-L
4Ph2SnO
{[Ph2SnL]3O2[Ph2Sn(OCH3)]}
+
11
4H-L
MeOH
Scheme 2.

1012
H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
Sn4: C, 56.25; H, 4.40; N, 5.55. Found: C, 56.52; H, 4.43;
N, 5.42%. IR (KBr, cmꢀ1): mas(COO), 1654; ms(COO),
1456; m(C@N), 1593; m(Sn–C), 552; m(Sn–O), 478; m(Sn–
1667; ms(COO), 1479; m(C@N), 1591; m(Sn–C), 576; m(Sn–
O), 481; m(Sn–N), 463; m(Sn–Cl), 270. H NMR (CDCl3,
ppm): d 3.08 (t, 8H, JSn–H = 94 Hz, –CH2–), 3.02 (t, 12H,
JSn–H = 79 Hz, –CH2–), 7.08–7.16 (m, 40H, Ph–H), 8.26
(br, 4H, pca–H), 9.13 (br, 4H, pca–H), 2.53 (s, 12H, pca–
1
1
N), 468; m(Sn–Cl), 268. H NMR (CDCl3, ppm): d 3.16
(t, 8H, JSn–H = 95 Hz, –CH2–), 3.09 (t, 12H, JSn–H
= 72 Hz, –CH2–), 6.85–7.10 (m, 50H, Ph–H), 8.76 (br,
4H, pca–H), 9.25 (br, 4H, pca–H), 2.55 (s, 12H, pca–
CH3). 13C NMR (CDCl3, ppm): d 32.26 (CH2Ar,
1J(119Sn–13C) = 596 Hz), d 33.7 (CH2Ar, 1J(119Sn–13C)
= 895 Hz), 28.7, 122.5 122.3, 127.1, 127.3, 151.7, 152.2,
154.6, 154.8 (Ar–C), 141.2, 142.5, 143.6, 147.4 (C4H3N2–),
171.6 (COO). 119Sn NMR (CDCl3, ppm): d ꢀ576.6, ꢀ56.6.
CH3). 13C NMR (CDCl3, ppm):
d 32.1 (CH2Ar,
1J(119Sn–13C), 610 Hz), d 33.7 (CH2Ar, 1J(119Sn–13C),
893 Hz), 28.5, 159.6, 157.5, 153.3, 129.3, 127.7, 125.7,
123.7 (Ar–C), 148.2, 147.2, 143.7, 141.6 (C4H3N2–), 173.5
(COO). 119Sn NMR (CDCl3, ppm): d ꢀ596.6, ꢀ58.7.
2.2.5. [(4-CNC6H4CH2)2Sn(pca)2ClSn(4-
CNC6H4CH2)3]2 5
Compound 5 is prepared in the same way as that of
compound 1. The solid is then recrystallized from metha-
nol. Yield: 58%. Mp 130–133 ꢁC. Anal. Calc. for
2.2.2. [(2-ClC6H4CH2)2Sn(pca)2ClSn(2-ClC6H4CH2)3]2
2
Compound 2 is prepared in the same way as that of
compound 1. The solid is then recrystallized from metha-
nol. Yield: 62%. Mp 125–127 ꢁC. Anal. Calc. for
C94H78Cl12N8O8Sn4: C, 48.08; H, 3.35; N, 4.77. Found:
C, 48.34; H, 3.41; N, 4.76%. IR (KBr, cmꢀ1): mas(COO),
1662; ms(COO), 1475; m(C@N), 1602; m(Sn–C), 567; m(Sn–
C104H78Cl2N18O8Sn4: C, 55.43; H, 3.49; N, 11.19. Found:
C, 55.58; H, 3.35; N, 11.06%. IR (KBr, cmꢀ1): mas(COO),
1671; ms(COO), 1491; m(C@N), 1606; m(Sn–C), 578; m(Sn–
1
O), 487; m(Sn–N), 465; m(Sn–Cl), 262. H NMR (CDCl3,
ppm): d 3.15 (t, 8H, JSn–H = 97 Hz, –CH2–), 3.04 (t, 12H,
JSn–H = 72 Hz, –CH2–), 7.11–7.24 (m, 40H, Ph–H), 8.70
(br, 4H, pca–H), 9.19 (br, 4H, pca–H), 2.53 (s, 12H, pca–
1
O), 482; m(Sn–N), 466; m(Sn–Cl), 267. H NMR (CDCl3,
CH3). 13C NMR (CDCl3, ppm):
d 32.0 (CH2Ar,
ppm): d 3.11 (t, 8H, JSn–H = 92 Hz, –CH2–), 3.02 (t, 12H,
JSn–H = 76 Hz, –CH2–), 7.08–7.21 (m, 40H, Ph–H), 8.68
(br, 4H, pca–H), 9.27 (br, 4H, pca–H), 2.56 (s, 12H, pca–
1J(119Sn–13C) = 603 Hz), d 33.7 (CH2Ar, 1J(119Sn–13C)
= 891 Hz), 28.6, 158.6, 157.4, 152.5, 127.1, 127.5, 122.1
(Ar–C), 143.5, 141.0, 143.2, 147.6 (C4H3N2–), 170.1
(COO). 119Sn NMR (CDCl3, ppm): d ꢀ522.8, ꢀ51.3.
CH3). 13C NMR (CDCl3, ppm):
d 31.1 (CH2Ar,
1J(119Sn–13C) = 598 Hz), d 33.7 (CH2Ar, 1J(119Sn–13C)
= 892 Hz), 28.6, 157.6, 154.6, 129.1, 128.4, 125.2 125.3,
124.7, 122.6 (Ar–C), 141.1, 142.6, 146.6, 147.8 (C4H3N2–),
172.5 (COO). 119Sn NMR (CDCl3, ppm): d ꢀ512.5, ꢀ55.8.
2.2.6. [(4-ClC6H4CH2)2Sn(pca)2ClSn(4- ClC6H4CH2)3]2
6
Compound 6 is prepared in the same way as that of
compound 1. The solid is then recrystallized from metha-
nol. Yield: 52%. Mp 126–128 ꢁC. Anal. Calc. for
C94H78Cl12N8O8Sn4: C, 48.08; H, 3.35; N, 4.77. Found:
C, 47.88; H, 3.41; N, 4.72%. IR (KBr, cmꢀ1): mas(COO),
1659; ms(COO), 1481; m(C@N), 1595; m(Sn–C), 558; m(Sn–
2.2.3. [(2-FC6H4CH2)2Sn(pca)2ClSn(2- FC6H4CH2)3]2 3
Compound 3 is prepared in the same way as that of
compound 1. The solid is then recrystallized from metha-
nol. Yield: 59%. Mp 121–122 ꢁC. Anal. Calc. for
C94H78Cl2F10N8O8Sn4: C, 51.71; H, 3.60; N, 5.13. Found:
C, 51.49; H, 3.73; N, 5.07%. IR (KBr, cmꢀ1): mas(COO),
1668; ms(COO), 1478; m(C@N), 1598; m(Sn–C), 538; m(Sn–
1
O), 481; m(Sn–N), 467; m(Sn–Cl), 268. H NMR (CDCl3,
ppm): d 3.14 (t, 8H, JSn–H = 93 Hz, –CH2–), 3.05 (t, 12H,
JSn–H = 74 Hz, –CH2–), 7.09–7.22 (m, 40H, Ph–H), 8.68
(br, 4H, pca–H), 9.23 (br, 4H, pca–H), 2.55 (s, 12H,
pca–CH3). 13C NMR (CDCl3, ppm): d 32.3 (CH2Ar,
1J(119Sn–13C) = 615 Hz), d 33.7 (CH2Ar, 1J(119Sn–13C)
= 892 Hz), 28.7, 163.5, 161.4, 158.6, 122.6 125.3 (Ar–C),
141.1, 142.2, 142.6, 146.6 (C4H3N2–), 173.8 (COO). 119Sn
NMR (CDCl3, ppm): d ꢀ536.5, ꢀ63.6.
1
O), 480; m(Sn–N), 462; m(Sn–Cl), 268. H NMR (CDCl3,
ppm): d 3.19 (t, 8H, JSn–H = 96 Hz, –CH2–), 3.08 (t, 12H,
JSn–H = 73 Hz, –CH2–), 7.09–7.18 (m, 40H, Ph–H), 8.76
(br, 4H, pca–H), 9.22 (br, 4H, pca–H), 2.55 (s, 12H, pca–
CH3). 13C NMR (CDCl3, ppm):
d
33.7
31.0 (CH2Ar,
(CH2Ar,
1J(119Sn–13C) = 598 Hz),
d
1J(119Sn–13C) = 894 Hz), 28.5, 161.7, 158.5, 156.4, 129.6,
127.5 128.5, 116.2, 115.5 (Ar–C), 142.2, 143.1, 144.5,
147.4 (C4H3N2–), 173.1 (COO). 119Sn NMR (CDCl3,
ppm): d ꢀ593.6, ꢀ52.2.
2.2.7. [(2,4- Cl2C6H3CH2)2Sn(pca)2ClSn(2,4-
Cl2C6H3CH2)3]2 7
Compound 7 is prepared in the same way as that of
compound 1. The solid is then recrystallized from metha-
nol.Yield: 79%. Mp 112–113 ꢁC. Anal. Calc. for
C94H68Cl22N8O8Sn4: C, 41.93; H, 2.55; N, 4.16. Found:
C, 42.11; H, 2.58; N, 4.03%. IR (KBr, cmꢀ1): mas(COO),
1668; ms(COO), 1471; m(C@N), 1592; m(Sn–C), 568; m(Sn–
2.2.4. [(4-FC6H4CH2)2Sn(pca)2ClSn(4- FC6H4CH2)3]2 4
Compound 4 is prepared in the same way as that of
compound 1. The solid is then recrystallized from metha-
nol.Yield: 69%. Mp 134–137 ꢁC. Anal. Calc. for
C94H78Cl2F10N8O8Sn4: C, 51.71; H, 3.60; N, 5.13. Found:
C, 51.56; H, 3.65; N, 5.09%. IR (KBr, cmꢀ1): mas(COO),
1
O), 483; m(Sn–N), 462; m(Sn–Cl), 265. H NMR (CDCl3,
ppm): d 3.21 (t, 8H, JSn–H = 97 Hz, –CH2–), 3.01 (t, 12H,

H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
1013
JSn–H = 78 Hz, –CH2–), 7.17–7.36 (m, 30H, Ph–H), 8.86
(br, 4H, pca–H), 9.26 (br, 4H, pca–H), 2.56 (s, 12H,
pca–CH3). 13C NMR (CDCl3, ppm): d 33.8 (CH2Ar,
1J(119Sn–13C) = 618 Hz), d 33.7 (CH2Ar, 1J(119Sn–13C)
= 876 Hz), 28.5, 169.1, 168.3, 161.8, 158.9, 157.3, 152.1,
152.1, 151.1, 122.5 122.3 (Ar–C), 142.1, 142.4, 142.6,
146.6 (C4H3N2–), 172.5 (COO). 119Sn NMR (CDCl3,
ppm): d ꢀ572.8, ꢀ56.8.
(bCH2), 26.7 (bCH2), 25.3 (cCH2), 25.1 (cCH2), 13.5
(CH3), 13.6 (CH3), 141.1, 142.2, 142.6, 146.6 (C4H2N2–),
30.4 (CH3Ar), 167.2 (COO). 119Sn NMR (CDCl3, ppm):
d ꢀ286.6, ꢀ202.6.
2.2.11. {[Ph2Sn(pca)]3O2[Ph2Sn(OCH3)]} 11
The complex 11 is prepared in the same way as that of
complex 10. The solid is then recrystallized from methanol
and the colorless crystal is obtained.Yield: 82%. Mp 91–
92 ꢁC. Anal. Calc. for C67H58N6O9Sn4: C, 51.39; H, 3.73;
N, 5.37. Found: C, 51.30; H, 3.82; N, 5.51%. IR (KBr,
cmꢀ1): mas(COO), 1669, 1604; ms(COO), 1384; 1471; 1565,
1480, 1438 (m, Ph); m(C@N), 1602, m(Sn–O–Sn), 681;
2.2.8. [(nBu)3Sn(pca)]
8
1
Compound 8 is prepared in the same way as that of
compound 1. The solid is then recrystallized from methanol
and the colorless crystal compound 8 is formed. Yield:
87%. Mp 90–92 ꢁC, Anal. Calc. for C36H64N4O4Sn2: C,
50.61; H, 7.55. Found: C, 50.60; H, 7.55%. IR (KBr,
cmꢀ1): mas(COO), 1584; ms(COO), 1423, m(C@N), 1596,
1
m(Sn–C), 579; m(Sn–O), 447. H NMR (CDCl3, ppm): d
9.61 (br, 3H, pca–H), 9.23 (br, 3H, pca–H), 7.32–8.45 (m,
40H, Ph–H); 3.92 (d, 3H, CH3O), 2.74 (s, 9H, ArCH3);
13C NMR (CDCl3, ppm): d 159.7, 159.2, 158.5, 152.1,
137.9, 137.3, 136.6, 136.4, 131.5, 131.2, 130.8, 130.3,
130.0, 129.8, 129.4, 129.2 (C6H5–), 51.3 (CH3O), 30.4
(CH3Ar), 173.2 (COO). 119Sn NMR (CDCl3, ppm): d
ꢀ480.5, ꢀ183.3.
1
m(Sn–C), 534; m(Sn–O), 465. H NMR (CDCl3, ppm): d
8.25–9.28 (m, 4H, pca), 2.34 (s, 6H, pca–CH3), 1.33–1.56
(m, 36H, –(CH2)3–), 0.99 (t, 18H, –CH3). 13C NMR
(CDCl3, ppm): d 26.7 (aCH2, 1J(119Sn–13C), 596 Hz),
119Sn NMR (CDCl3, ppm): d ꢀ46.5.
2.2.9. [(CH3)2Cl2Sn(pca)Sn(CH3)2(pca)]
9
2.3. X-ray crystallographic studies
1
Compound 9 is prepared in the same way as that of
compound 1. The solid is then recrystallized from methanol
and the colorless crystal compound 8 is formed. Yield:
80%. Mp 136–138 ꢁC. Anal. Calc. for C32H44Cl4N8O8Sn4:
C, 29.90; H, 3.45; N, 8.72. Found: C, 29.88; H, 3.48; N,
8.76%. IR (KBr, cmꢀ1): mas(COO), 1620; ms(COO), 1426;
m(C@N), 1586, m(Sn–C), 561, m(Sn–O), 479, m(Sn–N), 458,
X-ray crystallographic data for compounds 1 and 8– 11
were collected on a Bruker smart-1000 CCD diffractometer
˚
using MoKa radiations (0.71073 A). The structures were
solved by direct method and difference Fourier map using
SHELXL-97 program, and refined by full-matrix leastsquares
on F2. All non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were located at calculated positions
and refined isotropically. Further details are given in
Table 1.
1
m(Sn–Cl), 271; H NMR (CDCl3, ppm): d 0.85 (t, 12H,
JSn–H = 96 Hz, –CH3), 0.82 (t, 12H, JSn–H = 85 Hz, –
CH3), 8.70 (br, 4H, pca–H), 9.28 (br, 4H, pca–H), 2.61
(s, 12H, pca–CH3). 13C NMR (CDCl3, ppm): d 10.0
1
1
(CH3, J(119Sn–13C), 728 Hz), d 12.1 (CH3, J(119Sn–13C),
909 Hz), 143.6.2, 145.6, 145.6, 147.4 (C4H3N2–), 171.6
(COO). 119Sn NMR (CDCl3, ppm): d ꢀ375.6, ꢀ35.5.
3. Results and discussion
3.1. Spectroscopic studies
2.2.10. {[(nBu)2Sn(pca)]2O}2 10
3.1.1. IR spectra
The reaction is carried out under nitrogen atmosphere.
2-Methylpyrazine-5-acid (0.276, 2.0 mmol) are added to
the solution of dry benzene and methanol (5:1) of di-n-
butyltin oxide (0.498 g, 2.0 mmol) in a Schlenk flash.
The mixture gives a clear solution within 10–15 min.
Refluxing was continued for 10 h, the solvent is gradually
removed by evaporation under vacuum until solid prod-
uct is obtained. The solid is then recrystallized from meth-
anol and the colorless crystal is obtained. Yield: 86%. Mp
145–147 ꢁC. Anal. Calc. for C56H90N8O10Sn4: C, 44.54;
H, 6.01; N, 7.42. Found: C, 44.27; H, 6.11; N, 7.38%.
IR (KBr, cmꢀ1): mas(COO), 1665, 1617; ms(COO), 1388,
1464; m(C@N), 1598, m(Sn–C), 571; m(Sn–O–Sn), 627;
The stretching frequencies of interest are those associ-
ated with the acid COO, Sn–C, Sn–O, and Sn–N groups.
Above all , there are absorption peaks near 478 cmꢀ1 and
436– 458 cmꢀ1, which indicate that there are Sn–O and
Sn–N bonds in all compounds. All these values are con-
sistent with that detected in a number of organotin(IV)
derivatives [9,10]. Besides, in organotin carboxylate com-
pounds, the IR spectra can provide useful information
concerning the coordinate formation of the carboxyl.
The magnitude of (Dm = mas(COO) ꢀ ms(COO)) of about
in the band of 133–198 cmꢀ1 for compounds 1–11 is com-
parable to those for the corresponding sodium salts,
which indicates the presence of bidentate carboxyl groups
[11]. Moreover, the magnitude of Dm also occurring at
about 280 cmꢀ1 for compounds 10 and 11 indicates that
the carboxylate ligands function as the type of monoden-
tate except bidentate, which was also confirmed by X-ray
structure analyses.
1
m(Sn–O), 489; H NMR (CDCl3, ppm): d 9.56 (br, 4H,
pca–H), 9.19 (br, 4H, pca–H), 2.83 (s, 12H, ArCH3), d
0.87 (t, 24H, CH3), 1.10–1.58 (m, 48H, CH2CH2CH2),
13C NMR (CDCl3, ppm): d 26.7 (aCH2, 1J(119Sn–13C),
655 Hz), 27.3 (aCH2, 1J(119Sn–13C), 772 Hz), 26.5

1014
H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
Table 1
Crystal, data collection and structure refinement parameters for compounds 1 and 8–11
Compound
1
8
9
10
11
Empirical
C94.50H88Cl2N8O8.50Sn4 C36H64N4O4Sn2
C32H44Cl4N8O8Sn4
C56H90N8O10Sn4
C67H58N6O9Sn4
formula
Formula weight
Wavelength (A)
Crystal system
Space group
2017.39
0.71073
Triclinic
854.29
0.71073
Triclinic
1285.31
0.71073
Orthorhombic
Pna21
1510.12
0.71073
Triclinic
1565.95
0.71073
Monoclinic
P21/n
˚
ꢀ
ꢀ
ꢀ
P1
P1
P1
Unit cell dimension
˚
a (A)
12.427(2)
14.184(2)
15.843(3)
114.255(2)
103.927(2)
95.997(2)
1
10.6572(14)
11.5515(15)
18.860(3)
82.867(2)
78.588(2)
71.823(2)
2
30.205(7)
10.824(3)
7.2092(16)
90
90
90
2
12.176(3)
12.630(3)
13.292(3)
70.662(4)
69.435(3)
65.545(3)
1
12.220(3)
27.210(7)
21.423(6)
90
100.186(5)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
Z
4
Absorption
coefficient
1.138
1.194
2.373
1.507
1.464
(mmꢀ1
)
Crystal size (mm) 0.45 · 0.32 · 0.21
h Range for data 2.31–25.01
collection (ꢁ)
0.41 · 0.30 · 0.22
0.58 · 0.43 · 0.11
0.39 · 0.18 · 0.12
0.45 · 0.38 · 0.29
1.86–25.03
2.00–25.01
1.90–25.03
1.78–25.01
Index ranges
ꢀ14 6 h 6 9,
ꢀ16 6 k 6 15,
ꢀ15 6 l 6 18
12620
ꢀ12 6 h 6 11,
ꢀ13 6 k 6 11,
ꢀ22 6 l 6 22
11137
ꢀ29 6 h 6 35,
ꢀ12 6 k 6 10,
ꢀ8 6 l 6 8
11833
ꢀ14 6 h 6 14,
ꢀ15 6 k 6 9,
ꢀ15 6 l 6 15
9036
ꢀ14 6 h 6 14,
ꢀ32 6 k 6 32,
ꢀ14 6 l 6 25
35672
Reflections
collected
Unique
8334(0.0179)
7395(0.0267)
4154(0.0769)
5947(0.0303)
12062(0.1100)
reflections
(Rint
)
Absorption
correction
Refinement
method
Data/restrainst/
parameters
Goodness of fit
on F2
Semi-empirical from
equivalents
Full-matrix least-
squares on F2
Semi-empirical from
equivalents
Full-matrix least-squares Full-matrix least-
on F2
Semi-empirical from
equivalents
Semi-empirical from
equivalents
Full-matrix least-
squares on F2
5947/62/352
Semi-empirical from
equivalents
Full-matrix least-
squares on F2
squares on F2
4154/1/253
8334/421/596
7395/234/416
12062/36/779
1.056
1.001
1.002
1.031
1.003
Final R indices
[I > 2r(I)]
R indices (all
data)
R1 = 0.0395,
xR2 = 0.0924
R1 = 0.0695,
xR2 = 0.1127
R1 = 0.0518,
xR2 = 0.1320
R1 = 0.0620,
xR2 = 0.1407
R1 = 0.0448,
xR2 = 0.1079
R1 = 0.0530,
xR2 = 0.1146
R1 = 0.0555,
xR2 = 0.1287
R1 = 0.1097,
xR2 = 0.1591
R1 = 0.0647,
xR2 = 0.1450
R1 = 0.1760,
xR2 = 0.2062
3.1.2. NMR spectroscopic
four-coordinate from +200 to ꢀ60 in solution [16]. The
119Sn NMR spectrum of compounds 1–7 exhibit two sig-
nals at about d ꢀ51.3 to ꢀ63.6 and ꢀ512.5 to 593.6 ppm,
suggesting there are either 4- and 7-coordinate. The devia-
tion may be because the 119Sn NMR is influenced by sev-
eral factors, including the aromatic or aliphatic of the R
group bound to the tin atom (and possibly the type of
donor atoms of the ligand) [17]. Therefore it can reason-
ably be assumed that the intermolecular Sn–N or Sn–O
interaction of compounds 1–7 probably does not survive
in solution.
In 1H NMR spectra of the free ligand, single resonances
are observed at 7.02 ppm, which are absent in the spectra
of the compounds, indicating the replacement of the car-
1
boxylic acid proton by a organotin moiety. The H NMR
of compounds 1–7 show that the chemical shifts of the pro-
tons of methylene bound to tin atom (ArCH2Sn) exhibit
two signals at the region 3.01–3.21 ppm as triplets and indi-
cates that there are two different types of tin atoms, which
is also indicated by tin (119Sn)–hydrogen coupling [5,12,13].
The 13C NMR spectra of all compounds show a signif-
icant downfield shift of all carbon resonances, compared
with the free ligand. The shift is a consequence of an elec-
tron density transfer from the ligand to the acceptor.
119Sn NMR chemical shift values may be used to give
tentative indications of the environment around tin atoms.
Seven-coordinate Sn has d (119Sn) values ranging from
about ꢀ525 to ꢀ786 ppm, six-coordinate from ꢀ333 to
ꢀ395 ppm [14,15], five-coordinate from ꢀ90 to ꢀ190 and
3.2. Crystal structures
3.2.1. Crystal structure of [(PhCH2)2Sn(pca)2ClSn-
(PhCH2)3]2 Æ 0.5CH3OH 1
The molecular structure is illustrated in Fig. 1. Selected
˚
bond lengths (A) and angles (ꢁ) are listed in Table 2. The
compound prove to be tetranuclear macrocyclic compound

H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
1015
˚
radii of the tin and oxygen 2.13 A [19] both of which are
similar to those reported in the literature [20]. The Sn–Cl
˚
bond length [Sn(1)–Cl(1)] 2.5402(16) A lies in the range
˚
of the normal covalent radii (2.37–2.60 A) [21]. The Sn–C
distances fall in a narrow range from 2.139(6) to
˚
2.150(7) A, typical of organotin derivatives.
3.2.2. Crystal structure of [(nBu)3Sn(pca)] 8 and
1
[(CH3)2Cl2Sn(pca)Sn(CH3)2(pca)]
9
1
The molecular structure of compounds 8 and 9 are illus-
trated in Figs. 2–4, selected bond lengths (A) and angles (ꢁ)
˚
Fig. 1. Molecular structure of compound 1. For clarity, only the first
carbon atoms of the benzyl chains linked to Sn are shown.
are listed in Tables 3 and 4. As shown from Fig. 2, the crys-
tal structure of compound 8 possesses a continuous mean-
der-shaped polymeric chain structure and the asymmetric
molecular contains two independent tin atoms that are
practically superimposable. In fact correlative data of the
two tin atoms show only a very marginal difference in the
bond lengths and angles. Obviously, the tin atoms are con-
sidered as distorted trigonal bipyramidal with the axial site
occupied by the O atoms and the basal plane defined by
three C atoms from the R groups The tin–oxygen bond
Table 2
˚
Selected bond distances (A) and angles (ꢁ) for compound 1
Sn(1)–O(3)
Sn(1)–O(1)
Sn(1)–C(20)
Sn(1)–C(13)
Sn(1)–N(3)
Sn(1)–N(1)
O(1)–C(1)
O(3)–C(7)
O(1)–Sn(1)–N(1)
N(3)–Sn(1)–N(1)
C(20)–Sn(1)–C(13)
C(20)–Sn(1)–O(3)
C(13)–Sn(1)–O(3)
C(20)–Sn(1)–O(1)
C(13)–Sn(1)–O(1)
O(3)–Sn(1)–O(1)
C(20)–Sn(1)–N(3)
C(13)–Sn(1)–N(3)
Cl(1)–Sn(1)–N(1)
C(34)–Sn(2)–C(41)
C(34)–Sn(2)–O(2)
C(41)–Sn(2)–O(2)
C(27)–Sn(2)–O(4)#1
O(2)–Sn(2)–O(4)#1
2.307(4) Sn(1)–Cl(1)
2.381(4) Sn(2)–O(4)#1
2.144(7) Sn(2)–C(34)
2.145(7) Sn(2)–C(27)
2.504(5) Sn(2)–C(41)
2.606(5) Sn(2)–O(2)
1.239(7) O(2)–C(1)
1.238(7) O(4)–C(7)
65.12(14) O(3)–Sn(1)–N(1)
159.14(15) C(13)–Sn(1)–N(1)
2.5402(16)
2.312(4)
2.139(6)
2.144(7)
2.150(7)
2.216(4)
1.251(7)
1.222(7)
133.23(15)
92.9(2)
67.46(15)
135.52(15)
92.74(19)
92.3(2)
147.52(11)
144.36(11)
80.10(12)
85.5(2)
˚
lengths of 2.300(4) and 2.304(4) A are the evidence of the
174.3(3)
90.3(2)
86.8(2)
85.5(2)
88.9(2)
O(3)–Sn(1)–N(3)
O(1)–Sn(1)–N(3)
C(20)–Sn(1)–Cl(1)
C(13)–Sn(1)–Cl(1)
O(3)–Sn(1)–Cl(1)
68.11(14) O(1)–Sn(1)–Cl(1)
92.6(2)
90.8(2)
N(3)–Sn(1)–Cl(1)
C(20)–Sn(1)–N(1)
79.25(11) C(34)–Sn(2)–C(27)
118.2(3)
121.6(3)
91.9(3)
95.0(2)
78.1(3)
119.3(3)
97.7(2)
90.1(2)
C(27)–Sn(2)–C(41)
C(27)–Sn(2)–O(2)
C(34)–Sn(2)–O(4)#1
C(41)–Sn(2)–O(4)#1
87.7(3)
165.78(16)
with 2-methylpyrazine-5-acid bridging the adjacent tin
atoms with a twenty-member Sn4O8N4C4 ring. The unit
is [(PhCH2)2Sn(pca)ClSn(PhCH2)3], in which the primary
bonds of the two ligands to tins occur through their nitro-
gen atoms and four oxygen atoms of the carboxyl (mode
B). The compound exist in distorted pentagonal bipyrami-
dal about all four tin atoms with seven-coordinated tin(IV)
atom. The Sn–N bond lengths [Sn(1)–N(1)], 2.606(5) and
[Sn(1)–N(3)], 2.504(5) are totally in agreement with the
valence extension of the tin atom and lie within the sum
of their respective Van der Waal’s radii of the two atoms
Fig. 2. Molecular structure of compound 8.
˚
(3.74 A) [18]. The carboxylate ligand chelates two Sn atoms
with asymmetric Sn–O bond distances and this asymmetry
is reflected in the association with the shorter Sn–O bonds.
The degree of asymmetry in the Sn–O bond distances is not
equal, with the difference between Sn–O bond distance for
˚
the two carboxylate ligands being 0.165, 0.096 A, respec-
tively. Although the Sn–O ranges from 2.216(4) to
˚
Fig. 3. Molecular structure of compound 9.
2.381(4) A which is longer than the sum of the covalent

1016
H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
Table 4
Selected bond distances (A) and angles (ꢁ) for compound 9
˚
Sn(1)–C(14)
Sn(1)–C(13)
Sn(1)–O(1)
Sn(1)–O(4)#1
Sn(1)–O(3)
Sn(1)–N(1)
O(4)–Sn(1)#2
2.095(9)
2.100(9)
2.287(5)
2.311(6)
2.327(6)
2.487(7)
2.311(6)
Sn(1)–N(3)
Sn(2)–C(15)
Sn(2)–C(16)
Sn(2)–O(2)
Sn(2)–Cl(2)
Sn(2)–Cl(1)
2.496(7)
2.087(10)
2.117(10)
2.330(6)
2.393(3)
2.480(2)
C(14)–Sn(1)–C(13)
C(14)–Sn(1)–O(1)
C(13)–Sn(1)–O(1)
C(14)–Sn(1)–O(4)#1
C(13)–Sn(1)–O(4)#1
O(1)–Sn(1)–O(4)#1
C(14)–Sn(1)–O(3)
C(13)–Sn(1)–O(3)
O(1)–Sn(1)–O(3)
O(4)#1–Sn(1)–O(3)
C(14)–Sn(1)–N(1)
C(13)–Sn(1)–N(1)
O(1)–Sn(1)–N(1)
O(4)#1–Sn(1)–N(1)
O(3)–Sn(1)–N(1)
C(14)–Sn(1)–N(3)
177.2(4)
C(13)–Sn(1)–N(3)
O(1)–Sn(1)–N(3)
O(4)#1–Sn(1)–N(3)
O(3)–Sn(1)–N(3)
N(1)–Sn(1)–N(3)
C(15)–Sn(2)–C(16)
C(15)–Sn(2)–O(2)
C(16)–Sn(2)–O(2)
C(15)–Sn(2)–Cl(2)
C(16)–Sn(2)–Cl(2)
O(2)–Sn(2)–Cl(2)
C(15)–Sn(2)–Cl(1)
C(16)–Sn(2)–Cl(1)
O(2)–Sn(2)–Cl(1)
Cl(2)–Sn(2)–Cl(1)
C(7)–O(4)–Sn(1)#2
87.2(3)
74.1(2)
141.8(2)
67.2(2)
142.9(2)
144.5(4)
83.1(3)
89.5(3)
88.0(3)
87.9(3)
93.2(3)
144.1(2)
87.1(3)
95.7(3)
140.9(2)
74.8(2)
87.8(3)
90.0(3)
68.8(2)
75.3(2)
149.8(2)
93.5(3)
86.0(4)
106.6(3)
106.3(3)
86.60(19)
95.4(3)
96.1(3)
Fig. 4. The helical chain structure of compound 9, which are linked by
bridged carboxyl groups and the chain propagate through along the two-
fold screw axis.
177.9(2)
92.40(10)
132.5(6)
4. Its absolute configuration was successfully determined
by refining the Flack parameter [22]. This structure is made
up of infinite 1D zigzag chains. The chains propagate
through along the two-fold screw axis. If viewed down
the screw axis, it will show the symmetry quite well, which
propagate parallel for every other asymmetric units. In
every asymmetric unit, there exist two distinct tin environ-
ments and one kind of multi-coordination mode for ligands
chelated to tin (mode B). The coordination environment of
the Sn(1) center are distorted pentagonal bipyramid, in
which the deprotonated carboxylate groups bond to the
tin center in anisobidentate fashion. The compound con-
tains a seven-coordinated tin atom and the pentagonal
bipyramidal environment with C(13) and C(14) atoms
occupying the axial sites and the axial–Sn–axial, C(14)–
Sn(1)–C(13) is 177.2(4)ꢁ. Sn(1), N(1) and N(3), O(1),
O(3), O(4)#1 are completely coplanar with the tin atom
existing in the plane. The two chelating nitrogens occupy
trans positions. The sum of angles between the tin atom
and the equatorial atoms is 360.2ꢁ, consistent with the ideal
value of 360ꢁ. In the structure, two carbon atoms and one
oxygen atoms of 2-methylpyrazine-5-acid are covalently
Table 3
˚
Selected bond distances (A) and angles (ꢁ) for compound 8
Sn(1)–C(13)
Sn(1)–C(21)
Sn(1)–C(17)
Sn(1)–O(1)
Sn(1)–O(3)
Sn(2)–C(25)
C(13)–Sn(1)–C(21)
C(13)–Sn(1)–C(17)
C(21)–Sn(1)–C(17)
C(13)–Sn(1)–O(1)
C(21)–Sn(1)–O(1)
C(17)–Sn(1)–O(1)
C(13)–Sn(1)–O(3)
C(21)–Sn(1)–O(3)
C(17)–Sn(1)–O(3)
O(1)–Sn(1)–O(3)
C(25)–Sn(2)–C(29)
C(25)–Sn(2)–C(33)
C(29)–Sn(2)–C(33)
2.121(6)
2.137(7)
2.144(5)
2.300(4)
2.304(4)
2.106(6)
Sn(2)–C(29)
Sn(2)–C(33)
Sn(2)–O(2)
Sn(2)–O(4)#1
Sn(2)–O(4)
2.130(5)
2.133(6)
2.303(4)
2.307(4)
9.040(4)
130.7(3)
O(4)–Sn(2)#2
2.307(4)
85.59(19)
93.1(2)
91.7(2)
85.57(19)
87.2(2)
170.36(14)
116.4(2)
45.30(16)
102.4(2)
41.09(10)
129.50(11)
95.5(2)
114.0(2)
115.0(2)
91.1(2)
87.3(2)
85.16(18)
94.9(2)
C(29)–Sn(2)–O(2)
C(33)–Sn(2)–O(2)
C(25)–Sn(2)–O(4)#1
C(29)–Sn(2)–O(4)#1
C(33)–Sn(2)–O(4)#1
O(2)–Sn(2)–O(4)#1
C(25)–Sn(2)–O(4)
C(29)–Sn(2)–O(4)
C(33)–Sn(2)–O(4)
O(2)–Sn(2)–O(4)
O(4)#1–Sn(2)–O(4)
C(25)–Sn(2)–O(2)
94.3(2)
85.60(18)
170.42(14)
115.0(3)
129.3(3)
115.4(3)
evenness about bonds. The oxygen–tin–oxygen skeleton is
bent (170.42(14)ꢁ) and the distortion from idealized geom-
etry is also seen in the sum of the carbon–tin–carbon angles
(359.7ꢁ). Although the nitrogen atom from the pyrazine
ring of this ligand makes a close contact with Sn(2) at
3.258 A, and another nitrogen atom from the pyrazine ring
of another ligand makes a even closer contact to Sn(1) at
3.219 A, a distance is slightly less than the sum of the
van der Waal’s radii for Sn and N of 3.74 A [18]. Although
the weak SnÆN is not indicative of a significant bonding
interaction, it is perhaps the reason that the polymeric
chain take on meander-shaped but not linear.
The molecular structure of compound 9 is shown is Figs.
3 and 4, selected bond lengths and angles are listed in Table
˚
linked to the Sn(1). The Sn–O bond length (2.327(6) A)
are longer than those in {[nBu2Sn(2-pic)]2O}2 (2.0544 and
˚
2.110 A), near to the sum of the covalent radii of Sn and
˚
˚
O (2.13 A) [19]. The Sn–N bond lengths [Sn(1)–N (1) and
˚
Sn(1)–N(3), 2.487(7), 2.496(7) A, respectively] are longer
n
˚
˚
than those in Bu2Sn(pca)2(H2O) [2.2522(6) A] [23], but
˚
much shorter than the sum of the van der Waal’s radii of
˚
Sn and N, 3.74 A [18]. The Sn–O bond lengths [Sn(1)–
O(1) and Sn(1)–O(4)#1 [ꢀx,ꢀy + 1,z ꢀ 1/2], 2.287(5),
˚
2.311(6) A] are also below the sum of the van der Waal’s
˚
radii of these atoms, 3.68 A [18]. The overall configuration
at Sn(2) is best described as distorted trigonal bipyramid:

H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
1017
tin and the bonded oxygen and chlorine atoms are nearly
coplanar and deviate only slightly from regular trigonal
bipyramid geometry, mean deviation from plane is
˚
0.0133 A. The methyl groups occupy the apical position,
the axial–Sn–axial, C(13)–Sn(1)–C(14) is 177.2(4)ꢁ. The
˚
Sn–O distance 2.330(6) A, is in keeping with those reported
in Sn–O compounds [19] Me2SnCl(2-Pic) [24], Me2Sn(2-
Pic)2 [25] and {[nBu2Sn(2-Pic)]2O}2 [26].
It should be noted here that the compounds are inher-
ently chiral [27], moreover, in our case we can speak about
a significant helical twist in the coordination geometry,
since the angle between the two planes formed by the adja-
cent assymmertry units is 76.1ꢁ.
Fig. 6. Molecular structure of compound 11. For clarity, only the first
carbon atoms of the phenyls linked to Sn are shown.
3.2.3. Crystal structure of {[(nBu)2Sn(pca)]2O}2 10 and
{[Ph2Sn(pca)]3O2[Ph2Sn(OCH3)]} 11
˚
the tin atom deviating from the best plane by 0.0221 A.
The sum of angles between the tin atom and the equatorial
atoms is 360.07ꢁ. Compared to the ideal octahedral value
of 360ꢁ, this further testfies the atoms in the same plane.
The distortion from trigonal planar geometry is clearly also
related to the relatively short Sn1ÆN1 contacts. At
The molecular structure of compounds 10 and 11 are
˚
illustrated in Figs. 5 and 6, selected bond lengths (A) and
angles (ꢁ) are listed in Tables 5 and 6. There have being
significant intramolecular contacts in the crystal lattice.
As observed for the related structure [28–30], the core
geometry of the molecule consists of a centrosymmetric
planar four-membered Sn2O2 ring with two additional
nBu2Sn(pca) units attach at each bridging oxygen atom,
with the result that these oxygen atoms are three coordina-
tion. The two crystallographically unique 2-methylpyr-
azine-5-acid ligands coordinate in different ways (modes
A and C). The ligand contains the O(1) and O(2) atoms
bridging two tin atoms only via the O(1) atom. There are
two types of tin atom. For compound 10 (Fig. 5), the
Sn(1) atom is bonded to two carbon and four oxygen
˚
2.936(8) A, it is much shorter than the sum of the Van
der Waal’s radii of Sn and N, 3.74 A [18]. The coordination
˚
sphere of Sn(2) consists of two carbon and three oxygen
˚
atoms, with Sn(1)–O bond lengths of 1.993(5)–2.198(6) A.
The angles in the central Sn2O2 ring are 75.1(2)ꢁ and
104.9(2)ꢁ.
For compound 11 (Fig. 6), there are three distinct
coordinate ligands. Partial similar to the compound 10,
one of the carboxylates ligands is bidentate and bridge
a pair of tin atoms and the two other carboxylates are
monodentate. Differently, one of the two monodentate
carboxylates ligands bridge a pair of tin atoms through
O(4) atom resembling that of in compound 10, the other
only coordinates a exocyclic tin atom. Interestingly, on
˚
atoms, the longest Sn–O bond is 2.487(6) A, Sn(1)–O(1),
˚
while the others are between 2.096(5) and 2.386(6) A.
Two of the carboxylates ligands are bidentate and bridge
a pair of tin atoms and the two other carboxylates are
monodentate and coordinate each exocyclic tin atom.
The coordination geometry of the tin atom Sn(1) is a
distorted octahedron. C(13) and C(17) atoms occupy the
apical sites and C(13)–Sn(1)–C(17), is 152.3(4)ꢁ. Sn(1),
O(1), O(5)#1, O(5), and O(3) are almost coplanar with
Table 5
˚
Selected bond distances (A) and angles (ꢁ) for compound 10
Sn(1)–O(5)#1
Sn(1)–C(13)
Sn(1)–C(17)
Sn(1)–O(5)
Sn(1)–O(3)
Sn(1)–O(1)
Sn(1)–N(1)
2.096(5)
2.111(8)
2.119(8)
2.166(5)
2.386(6)
2.487(6)
2.936(8)
O(5)–Sn(1)#1
Sn(2)–O(5)
Sn(2)–C(25)
Sn(2)–C(21)
Sn(2)–O(4)#1
Sn(2)–O(1)
O(4)–Sn(2)#1
2.096(5)
1.993(5)
2.096(13)
2.170(12)
2.182(7)
2.198(6)
2.182(7)
76.6(3)
O(5)#1–Sn(1)–C(13)
O(5)#1–Sn(1)–C(17)
C(13)–Sn(1)–C(17)
O(5)#1–Sn(1)–O(5)
C(13)–Sn(1)–O(5)
C(17)–Sn(1)–O(5)
O(5)#1–Sn(1)–O(3)
C(13)–Sn(1)–O(3)
C(17)–Sn(1)–O(3)
O(5)–Sn(1)–O(3)
O(5)#1–Sn(1)–O(1)
C(13)–Sn(1)–O(1)
C(17)–Sn(1)–O(1)
O(5)–Sn(1)–O(1)
O(3)–Sn(1)–O(1)
O(5)#1–Sn(1)–N(1)
102.9(3)
C(13)–Sn(1)–N(1)
C(17)–Sn(1)–N(1)
O(5)–Sn(1)–N(1)
O(3)–Sn(1)–N(1)
O(1)–Sn(1)–N(1)
O(5)–Sn(2)–C(25)
O(5)–Sn(2)–C(21)
C(25)–Sn(2)–C(21)
O(5)–Sn(2)–O(4)#1
C(25)–Sn(2)–O(4)#1
C(21)–Sn(2)–O(4)#1
O(5)–Sn(2)–O(1)
C(25)–Sn(2)–O(1)
C(21)–Sn(2)–O(1)
O(4)#1–Sn(2)–O(1)
102.5(3)
152.3(4)
75.1(2)
97.0(3)
99.8(3)
87.7(2)
84.8(3)
85.6(3)
162.7(2)
142.4(2)
83.7(3)
82.8(3)
67.27(19)
130.0(2)
159.6(2)
75.7(3)
125.2(2)
72.0(2)
58.0(2)
113.7(4)
114.2(4)
130.9(5)
93.3(2)
93.7(4)
93.6(4)
76.2(2)
92.8(4)
88.6(4)
169.2(2)
Fig. 5. Molecular structure of compound 10.

1018
H.D. Yin et al. / Journal of Organometallic Chemistry 692 (2007) 1010–1019
Table 6
are bidentate The directionality of this interaction involv-
ing the exocyclic tin atom Sn or the endocyclic tin almost
mimics that of in compound 10. The angles in the central
Sn2O2 ring are 72.0(3)ꢁ and 107.0(3)ꢁ.
˚
Selected bond distances (A) and angles (ꢁ) for compound 11
Sn(1)–O(3)
Sn(1)–C(7)
Sn(1)–O(6)
Sn(1)–C(1)
Sn(1)–O(4)
Sn(1)–N(5)
Sn(2)–C(19)
Sn(2)–O(3)
Sn(2)–C(13)
Sn(4)–O(2)
Sn(4)–O(1)
Sn(4)–C(43)
O(3)–Sn(1)–C(7)
O(3)–Sn(1)–O(6)
C(7)–Sn(1)–O(6)
O(3)–Sn(1)–C(1)
C(7)–Sn(1)–C(1)
O(6)–Sn(1)–C(1)
O(3)–Sn(1)–O(4)
C(7)–Sn(1)–O(4)
O(6)–Sn(1)–O(4)
C(1)–Sn(1)–O(4)
O(3)–Sn(1)–N(5)
C(7)–Sn(1)–N(5)
O(6)–Sn(1)–N(5)
C(1)–Sn(1)–N(5)
O(4)–Sn(1)–N(5)
C(19)–Sn(2)–N(3)
O(3)–Sn(2)–N(3)
C(13)–Sn(2)–N(3)
C(19)–Sn(2)–O(8)
O(3)–Sn(2)–O(8)
C(19)–Sn(2)–O(3)
C(19)–Sn(2)–C(13)
O(3)–Sn(2)–C(13)
C(19)–Sn(2)–O(2)
O(3)–Sn(2)–O(2)
C(13)–Sn(2)–O(2)
C(19)–Sn(2)–O(4)
O(3)–Sn(2)–O(4)
2.013(7)
2.100(12)
2.121(10)
2.161(14)
2.380(8)
2.614(12)
2.133(11)
2.136(8)
2.147(11)
1.993(7)
2.108(8)
2.112(13)
Sn(2)–O(2)
Sn(2)–O(4)
Sn(2)–O(8)
Sn(2)–N(3)
Sn(3)–O(3)
Sn(3)–O(2)
Sn(3)–C(25)
Sn(3)–C(31)
2.184(7)
2.363(7)
2.393(7)
2.618(10)
2.052(8)
2.063(7)
2.113(12)
2.131(12)
2.244(8)
2.121(13)
2.179(9)
91.9(4)
141.0(3)
83.5(3)
81.2(3)
137.8(3)
154.9(3)
64.0(3)
3.3. Conclusion
2-Methylpyrazine-5-acid has been shown to be able to
form monomeric, polymeric and tetranuclear macrocyclic
compounds. The nuclearity and stoichiometry were found
to depend on the nature of the starting acceptor and reac-
tion conditions. The ligand chelates to one tin, bonding
through the oxygen of carboxyl and the nitrogen atoms.
In the monomeric compounds, the ligand is bidentate or
monodentate and the coordinate numbers of the tin atom
is five or six. When using a series of benzyl triorganotin(IV)
chloride react with it, we can obtain the corresponding
tetranuclear macrocyclic compounds possess seven-coordi-
nate and five-coordinate tin atoms and the ligand is triden-
tate. It is noteworthy that dealkyltion reaction often
occurred. In the polymeric compounds, in view of the
highly variable coordination numbers and geometries of
tin centers the synthesis of helical chain organotin(IV)
architectures, where the building units are linked via dative
bonds represent an excellent challenge.
Sn(3)–O(1)
Sn(4)–C(37)
Sn(4)–O(9)
C(13)–Sn(2)–O(4)
O(2)–Sn(2)–O(4)
C(13)–Sn(2)–O(8)
O(2)–Sn(2)–O(8)
O(4)–Sn(2)–O(8)
O(2)–Sn(2)–N(3)
O(4)–Sn(2)–N(3)
O(8)–Sn(2)–N(3)
O(3)–Sn(3)–O(2)
O(3)–Sn(3)–C(25)
O(2)–Sn(3)–C(25)
O(3)–Sn(3)–C(31)
O(2)–Sn(3)–C(31)
C(25)–Sn(3)–C(31)
O(3)–Sn(3)–O(1)
O(2)–Sn(3)–O(1)
C(25)–Sn(3)–O(1)
C(31)–Sn(3)–O(1)
O(2)–Sn(4)–O(1)
O(2)–Sn(4)–C(43)
O(1)–Sn(4)–C(43)
O(2)–Sn(4)–C(37)
O(1)–Sn(4)–C(37)
C(43)–Sn(4)–C(37)
O(2)–Sn(4)–O(9)
O(1)–Sn(4)–O(9)
C(43)–Sn(4)–O(9)
C(37)–Sn(4)–O(9)
108.3(4)
80.2(3)
102.4(5)
108.6(4)
138.9(5)
101.1(4)
70.7(3)
89.2(4)
150.7(3)
86.4(4)
148.3(4)
77.3(4)
68.2(4)
80.8(4)
141.0(4)
85.8(4)
133.1(3)
83.2(4)
84.4(4)
153.1(3)
95.6(4)
165.5(4)
98.9(4)
94.1(4)
72.0(3)
91.9(4)
91.8(4)
69.1(3)
73.8(3)
76.2(3)
104.1(4)
116.6(4)
101.8(4)
115.3(4)
126.0(5)
147.2(3)
71.0(3)
90.6(4)
92.4(4)
75.2(3)
114.0(4)
98.2(5)
121.7(4)
95.2(4)
124.3(5)
91.7(3)
166.1(3)
91.3(5)
87.7(4)
Acknowledgements
We acknowledged the National Natural Foundation,
PR China (20543004) and the Shandong Province Science
Foundation (2005ZX09).
Appendix A. Supplementary material
CCDCs 606715 (1), 287658 (8), 287659 (9), 606713 (10),
and 606714 (11) contain the supplementary crystallo-
graphic data for 1, 8, 9, 10, and 11. The data can be
obtained free of charge via htpp://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2006.10.061.
another place, a methanol molecule replace the carboxy-
lates ligand as a unique ligand. The Sn(2) and Sn(3)
atoms are bonded to two carbon and to four oxygen
atoms, two carbon and to three oxygen atoms, resulting
in the coordination geometries of the tin atom Sn(2)
and Sn(3) are distorted octahedron and trigonal bipyrami-
˚
dal, respectively. The longest Sn–O bonds are 2.393(7) A,
Sn(2)–O(8) and 2.244(8) A, Sn(3)–O(1). The exocyclic tin
˚
atoms, take Sn(1) for example, forms three short Sn–O
bonds with three oxygen atoms. Together with the two
bonds to phenyltin groups, the Sn(1) atoms may be con-
sidered as distorted trigonal bipyramidal with the axial
site (O(6)–Sn(1)–O(4), 150.7(3)ꢁ) occupied by the O(4)
and O(6) atoms and the basal plane defined by O(3),
C(1), and C(7). It is noteworthy that short contacts are
recognized between SnÆN derived from the monodentate
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