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It is different from the reaction of Ph2C(OH)COOH and n-BuSn(O)OH, the latter is a hexanuclear
drum organotin oxo cluster [18]. For the latter, each of the Sn atoms has a coordination number of six, the
hydroxyl O atom is not involved in the coordination, and the Sn-O bonds are laying in 0.2079~0.2188
nm, which are slightly shorter than those in the title compound, so there is a notable difference between
these two compounds. It may mean that the number of alkyl attached to the central tin atoms plays an
important role in the self-assembly process.
此致！
敬礼！
庾江喜
2013 年 11 月 15 日
Synthesis, Crystal Structure,
Quantum Chemistry of a
One-Dimensional Chain Di(n-butyl)tin Benzilicarboxylate①
Jiang-Xi Yua,b Dai-Zhi Kuanga,b,② Yong-Lan Fenga,b Wu-Jiu Jianga,b
Xiao-Ming Zhua,b Fu-Xing Zhanga,b Jian-Qiu Wanga,b
(aKey Laboratory of Functional Organometallic Materials of College of Hunan Province, Hengyang
421008; bDepartment of Chemistry and Material Science, Hengyang Normal University, Hengyang
421008, China )
Abstract: A novel diorganotin(IV) compound [n-Bu2SnO2CC(O)Ph2]n has been synthesized by
dibutyltin oxide with benzilic acid in methanol. It was characterized by IR, elemental analysis and X-ray
single crystal diffraction. The crystal belongs to monoclinic system, space group Cc with the cell
parameters: a=1.84719(8) nm, b=1.20544(5) nm, c=1.03570(4) nm, β=112.571(3)°, V=2.12953(15) nm3,
Z=4, Dc=1.431 Mg·m-3, (MoKa)=1.217 mm-1, F(000)=936, R1=0.0488 and wR2=0.0953. The structural
①This work was supported by Natural Science Foundation of Hunan Province (No.13JJ3112), Scientific & Technological Projects of
Hunan Province (No.2013TZ2025), the Open Fund Project of Key Laboratory in Hunan Universities (13K105), Scientific Research Fund
of Hunan Provincial Education Department (No.12C0537), Scientific & Technological Projects of Hengyang City (No.2011KG56,
2012KJ30), the Youth Backbone Teacher Training Program of Hengyang Normal University (2012).
②Corresponding author: Dai-Zhi Kuang, male, 58 years old, professor, Research orientation: organometallic chemistry, E-mail:
hnkcq@qq.com.
analyses reveals that the compound is a one-dimensional infinite chain coordination polymer, each tin
atom is five-coordinated distorted trigonal bipyramidal configuration. Moreover, A 3D supramolecular
structure of the compound is assembled by intermolecular C–H···π interactions between the butyl group
and the benzene ring in an adjacent chain. CCDC: 837452
Keywords: diorganotin, benzilic acid, crystal structure, supramolecular compound, quantum chemistry
一维链状二丁基锡二苯乙醇酸酯的合成、晶体结构及量子
化学研究
庾江喜a,b
邝代治a,b,② 冯泳兰a,b 蒋伍玖a,b
朱小明a,b
张复兴a,b
(a 功能金属有机材料湖南省普通高等学校重点实验室, 衡阳 421008;
b
王剑秋a,b
衡阳师范学院化学与材料
科学系, 衡阳 421008)
摘要：在甲醇中二丁基氧化锡与二苯乙醇酸反应，合成了一个新颖的二烃基锡化合物
[n-Bu2SnO2CC(O)Ph2]n。经 IR、元素分析和 X-射线单晶衍射表征结构。该配合物晶体属单斜晶系，
空间群 Cc，晶胞参数：a=1.84719(8) nm，b=1.20544(5) nm，c=1.03570(4) nm，β=112.571(3)°，
V=2.12953(15) nm3 ，Z=4，Dc=1.431 Mg·m-3 ， (MoKa)=1.217 mm-1 ，F(000)=936，R1=0.0488，
wR2=0.0953。晶体结构分析表明：化合物为一维无限链状配位聚合物，中心锡原子为五配位畸变
三角双锥构型。两相邻配位聚合链间，通过丁基氢与另链苯环发生 C–H···π 作用，扩展成三维超
分子结构。
关键词：二烃基锡；二苯乙醇酸；晶体结构；超分子化合物；量子化学
1. Introduction
In recent years, the molecular self-assembly via intermolecular non-covalent interactions has
emerged as a powerful tool for the design and realization of intriguing supramolecular architectures.
These self-assembled motifs have attracted increasing attention for their potential applications such as
electronic, magnetic, optical and catalytic materials [1-4]. One of the most common ligands is multidentate
aromatic ligand, reacting with metal ions, that can easily form extended network structures through
various combinations of different types of intermolecular non-covalent interactions (hydrogen bonds,
π…π stacking and C–H…π interactions).
Although considerable progress has been made in the development of self-assembled chemistry,
only a few of main-group organometallic species have been reported so far [5,6]. Among them, organotin
compounds are awaking more and more interest, owing to their structural diversity
activity
[9,10]
as well as their application as catalysts in organic synthesis
[11,12].
[7,8],
high biological
Many novel organotin
compounds have been obtained, such as monomers, dimers, trimers, tetramers, oligomeric ladders, and
hexameric drums [13-18]. In our previous work, we have also reported several novel organotin compounds,
containing tetranuclear organotin oxo clusters
[19,20],
and 1D chain organotin polymers
[21,22],
some of
which have shown excellent electrochemical activity. As a continuation of our research, we report here
the syntheses and characterization of [n-Bu2SnO2CC(O)Ph2]n.
2. Experimental
2.1 Materials and methods
All reagents were of analytical grade and used without further purification. The melting points was
obtained on an X-4 microscopic melting point apparatus and is uncorrected. IR spectra (KBr pellets)
was recorded on a Shimadzu FTIR 8700 spectrometer (4000- 400 cm-1 range). Elemental analysis of C
and H was performed with a Perkin-Elmer 2400 II elemental analyser.
2.2 Synthesis of the compound
To a methanol solution (20 ml) of benzilic acid (0.228g, 1mmol), Bu2SnO (0.249g, 1mmol) was
added. The mixture was stirred and heated at reflux for 1 h. After cooling down to ambient temperature,
the solution was filtered. Colorless crystals suitable for X-ray analysis were obtained by the slow
evaporation of methanol solution at room temperature after a few days. Yield: 0.293g (63.8%). M.p.＞
300 ℃. Anal. Calc. For C22H28O3Sn: C, 57.55; H, 6.15. Found: C, 57.59; H, 6.23. IR (cm-1 ): 3057.0 (w,
νPh-H); 2956.7, 2925.8, 2862.2 (m, νC-H); 1562.2 (s, νasCOO-); 1402.2 (m, νsCOO-); 565.1 (w, νSn-O); 443.6
(w, νSn-C). The low solubility of this compound in common solvents has made it impossible for us to
investigate by NMR spectroscopy what kind of coordinated environment of Sn atom in the solid state.
2.3 Determination of crystal structure
X-ray diffraction data for the crystal was performed with graphite monochromated Mo Ka radiation
( λ= 0.071073 nm ) on a Bruker Smart Apex II CCD diffractometer, and collected by the φ–ω scan
technique at 296(2) K. Multi-scan absorption correction was applied to the data. The crystal structure
was solved by direct methods and refined by full-matrix least-squares on F2. All the non-hydrogen atoms
were located in successive difference Fourier syntheses and then refined anisotropically. Hydrogen
atoms were placed in calculated positions and refined isotropically with the isotropic vibration
parameters related to the parent atom. All calculations were performed with SHELXTL-97 programs.
Figures 1−2 were obtained from the DIAMOND 3.1c software package. The crystal data and structure
refinement parameters of this compound are listed in Table 1. CCDC: 837452
Table 1. Crystal data and structure refinement parameters of the compound
Empirical formula
C22H28O3Sn
Absorption coefficient (mm−1)
1.217
Formula weight
458.93
F(000)
936
Temperature (K)
296(2)
Crystal size (mm)
0.14 × 0.13 × 0.09
Wavelength (nm)
0.071073
θ range for data collection (°)
2.07 to 25.05
Crystal system
Monoclinic
Limiting indices
-22 ≤ h ≤ 22, -14 ≤ k ≤ 11, -12 ≤ l ≤ 12
Space group
Cc
Reflections collected / unique
5878 / 3337 (Rint = 0.0415)
a (nm)
1.84719(8)
Completeness to theta (%)
99.9
b (nm)
1.20544(5)
Data / restraints / parameters
3337 / 442 / 236
2
c (nm)
1.03570(4)
Goodness-of-fit on F
β (°)
112.571(3)
Final R indices [I >2σ(I)]
R1 = 0.0488, wR2 = 0.0953
volume (nm3)
2.12953(15)
R indices (all data)
R1 = 0.0897, wR2 = 0.1066
Z
4
Dc (Mg·m-3)
1.431
Largest diff. Peak and hole
(e·nm-3)
0.989
336 and -339
3. Results and discussion
3.1 IR Spectra
The IR spectra of the compound have been identified in comparison with that of free ligand. A
broad band in the region 2500–3300 cm-1 in the IR spectrum of free ligand attributed to the stretching
vibrations of OH group
[23]
, which is disappeared in the IR spectra of the compound due to the
deprotonation, that indicates metal-ligand bond formation through the site. For this compound, the weak
absorption bond appeared at 3057 cm-1 and the medium intensity bands observed at 2957, 2926, 2862
cm-1 are assigned to the C-H stretching vibrations of Ph and butyl, reapectively
[18, 21]
. The frequency of
νas(COO) and νs(COO) stretching vibrations observed at 1719 and 1342 cm in the spectrum of the
-1
ligand are shifted separately to 1562 cm-1 and 1402 cm-1 in the compound. The △ν(νas(COO)－νs(COO))
value of the compound (160 cm-1 ) indicates bridging bidentate coordination of the carboxylate ligand [24].
The stretching frequencies appear at 565 cm-1 for ν(Sn-O) and 444 cm-1 for ν(Sn-C), which are consistent
with the literature data [25, 26].
3.2 Description of the structure
Molecular structure of the compound is shown in Figure 1, Selected bond lengths and angles are
given in Table 2.
Figure 1. Molecular structure of the compound with 10% probability ellipsoids (i: x, 1-y, -1/2+z) (Hydrogen atoms are
omitted for clarity).
Table 2. Selected bond lengths (nm) and angles (°) for the compound
Sn(1)-C(1)
0.2117(12)
C(1)-Sn(1)-O(1)i
90.2(4)
Sn(1)-C(5)
0.2068(12)
C(5)-Sn(1)-O(1)i
96.8(4)
Sn(1)-O(3)
0.1976(6)
O(3)-Sn(1)-O(1)i
84.4(2)
Sn(1)-O(2)
0.2222(5)
C(1)-Sn(1)-O(2)
91.7(4)
Sn(1)-O(1)i
0.2176(5)
C(5)-Sn(1)-O(2)
97.9(4)
C(1)-Sn(1)-C(5)
124.8(5)
O(3)-Sn(1)-O(2)
77.9(2)
C(1)-Sn(1)-O(3)
120.3(3)
O(1)i-Sn(1)-O(2)
160.6(2)
C(5)-Sn(1)-O(3)
114.8(5)
Symmetry code: i: x, 1-y, -1/2+z.
From Figure 1, we can see that the central tin atom is five-coordinated trigonal bipyramid geometry
with two butyl C atoms and the O atom of the hydroxyl in equatorial positions, the sum of the angles
[C1-Sn1-C5 124.8°, C1-Sn1-O3 120.3°, C5-Sn1-O3 114.8° ] is 359.9°, which shows that Sn1, C1, C5
and O3 are basically planar, but the bond lengths [Sn1-C1 0.2117 nm, Sn1-C5 0.2068 nm, Sn1-O3
0.1976 nm ] are unequal, it proves the distortion of the geometry. The Sn1-O3 bond length is obviously
shorter than the Sn-O covalent bond length (0.216 nm)
[27]
, which reveals that the hydroxyl O atom is
coordinated to the tin atom by a strong chemical bond. Two O atoms of two different carboxylate ligands
occupy the axial positions, the axial O1i-Sn1-O2 angle is not 180° but 160.6(2)°. The Sn1-O1i, Sn1-O2
bond lengths are 0.2176, 0.2222 nm respectively, which are slightly longer than the Sn-O covalent bond
length but considerably shorter than the sum of the van der Waals radii of the two atoms (0.368 nm) [28].
It shows the carboxylate O atom and tin atom are bonding with a stable coordination bond. This O→Sn
coordination result in the formation of a one-dimensional infinite chain (Figure 2). It is different from the
reaction of Ph2C(OH)COOH and n-BuSn(O)OH, the latter is a hexanuclear drum organotin oxo cluster
[18].
For the latter, each of the Sn atoms has a coordination number of six, the hydroxyl O atom is not
involved in the coordination, and the Sn-O bonds are laying in 0.2079~0.2188 nm, which are slightly
shorter than those in the title compound, so there is a notable difference between these two compounds.
It may mean that the number of alkyl attached to the central tin atoms plays an important role in the
self-assembly process.
Moreover, the C−H…π interaction is observed between the butyl group and the benzene ring in an
adjacent chain(Figure 3a), which leads to the forming of a interesting 3D supramolecular network
(Figure 3b).
Figure 2. 1D infinite structure of the compound (Butyl and phenyl groups are omitted for clarity).
(a)
(b)
Figure 3. (a) Intermolecular C−H…π interactions [C8−H8A…π(C17ii−C22ii) 0.3080 nm] (ii: 1/2+x, 3/2-y, 1/2+z). (b) 3D
supramolecular structure of the compound by C−H…π interactions. (Some butyl and phenyl groups are omitted for
clarity).
3.3 Quantum chemistry
According to the method described in reference
[17, 19],
the atoms of the compound are divided into
four groups (C; H; O; Sn ), and quantum chemistry calculation of the compound was performed with
Gaussian03W program at B3LYP/LANL2DZ level.
In general, the stability of the structural unit is closely related to the total energy of the system and
the frontier orbital energy. For this compound, the total molecular energy is -1083.60730119 a.u., the
energies of HOMO and LUMO are -0.21150, -0.09587 a.u. respectively, and the △E(ELUMO-EHOMO)
value is 0.11563 a.u., which shows the compound is fairly stable.
The frontier orbital component of the compound is shown in Figure 4, the contributions of C, H, O
and Sn atoms to HOMO and LUMO are listed in Table 3. We can see that the HOMO is composed
chiefly of O and C atoms (the sum of the two is 98.43%), while the LUMO is mainly formed by Sn and
C atoms (the sum is 92.26%). Certainly when electron transfer occurs from ground state to excited state,
electrons mainly transfer from the carboxyl O atoms to the Sn atom to generate a charge transfer
compound.
Figure 4. Schematic diagram of frontier MO for the compound
Table 3. The calculated some frontier molecular orbitals composition (%) of the compound at LanL2DZ level
MO
E/a.u.
C
H
O
Sn
94HOMO
-0.21150
33.74
0.65
64.69
0.92
95LUMO
-0.09587
40.88
1.98
5.76
51.38
4. Conclusion
A novel dibutyltin(IV) compound based on benzilic acid ligand has been synthesized. The structural
analyses reveals that the compound is a one-dimensional infinite chain coordination polymer, each
central tin atom is five-coordinated distorted trigonal bipyramidal configuration. The 3D supramolecular
structure is also formed by C−H…π interactions, which indicates the weak intermolecular interactions
have enormous potential for constructing organometallic supramolecular frameworks.
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