Cage-like Carboxyl bridged octaphenyltetraantimony compounds (SbPh2)4(μ-O)4(μ-OH)2(μ- O2CR)2: Synthesis and structural characterization

Article abstract of DOI:10.1002/zaac.201100513

The metal-directed self-assembly of biphenylantimony trichloride and homocarboxylic acids LH [L = 2-CHO-C₆H₄COO^- (1), 2, 3-2F-C₆H₄COO^- (2), 4-CF ₃-C₆H₄COO^- (3)] provided three novel tetranuclear organoantimony(V) complexes, which were characterized by elemental analysis, FT-IR, ¹H, and ¹³C NMR spectroscopy as well as melting point, and X-ray single crystal analysis. In the molecular structure, four hexacoordinate antimony atoms are linked into a [Sb₂(μ-O) ₂]₂(μ-O)₂ cage architecture by oxo-bridges which are terminally bridged by two carboxyl groups. Copyright

Full text of DOI:10.1002/zaac.201100513

ARTICLE
DOI: 10.1002/zaac.201100513
“
Cage-like” Carboxyl Bridged Octaphenyltetraantimony Compounds
(
SbPh ) (μ-O) (μ-OH) (μ-O CR) : Synthesis and Structural Characterization
2
4
4
2
2
2
[a]
[a]
[a]
[a]
Handong Yin,* Qingkun Wu, Min Hong, and Wenkuan Li
Keywords: Biphenyl; Antimony; Tetranuclear; Cage; Crystal structure
Abstract. The metal-directed self-assembly of biphenylantimony tri-
as melting point, and X-ray single crystal analysis. In the molecular
COO (1), structure, four hexacoordinate antimony atoms are linked into a
COO– (3)] provided three novel
[Sb (μ-O) (μ-O) “cage” architecture by oxo-bridges which are ter-
tetranuclear organoantimony(V) complexes, which were characterized minally bridged by two carboxyl groups.
–
chloride and homocarboxylic acids LH [L = 2-CHO-C
6 4
H
2
,3-2F-C –C
6
H
4
COO– (2), 4-CF
3
6
H
4
2
2
]
2
2
1
13
by elemental analysis, FT-IR, H, and C NMR spectroscopy as well
Introduction
the obtained organoantimony(V) compounds are mononu-
clear.[ In contrast, only a few dinuclear and multinuclear or-
ganoantimony complexes have been reported so far. In order
1]
Organoantimony compounds are playing essential roles in
many aspects of neoteric chemistry, because of their diverse
structural chemistry, which arises partly from the various local
coordination spheres, and their potential applications. Tradi-
tional research on organoantimony compounds mostly focuses
on the structural diversity and a large number of organoanti-
mony derivatives derived from carboxylates, oximates, halides,
[5]
to generate more information on this subject and to relieve
the steric effect especially, diphenylantimony trichloride was
synthesized and utilized to construct organoantimony com-
[6]
plexes. Among the most common ligands used for the con-
struction of organoantimony(V) compounds with mono- or
multinuclear structures are carboxylic acids, which are able
to coordinate to central metal atoms in many ways, such as
unidentate, chelating-bidentate, and bridging-bidentate. Con-
sidering their various coordination modes and potential bioac-
tivity, we choose three structurally similar carboxylic acids LH
[1]
alkoxyls, and sulfonates have been synthesized. A growing
number of chemists have turned attention exploring their appli-
cations. For example, an organoantimony complex has been
used as a catalyst for direct diastereoselective Mannich reac-
tion in water.[ Antimony was also incorporated into thermo-
electric materials such as Sb Te and Ag Pb SbTe to mod-
2]
–
–
[
L = 2-CHO-C H COO (1), 2,3-2F-C H COO (2), and 4-
6 4 6 4
–
2
3]
3
1–x 18
20
CF –C H COO (3)], which are bound to electron with-
3 6 4
ify the physical properties.[ One of the most promising fields
is the exploration of their bioactivity and several articles re-
lated to this subject have been reported.[ Because coordina-
tion number, types of ligand, and molecular structures exert
influence on the performance of bioactivity, a substantial
number of organoantimony derivatives need to be synthesized
in order to investigate the mechanism and to explore the struc-
ture-activity relationship. The structural characterization of
such organoantimony compounds will, in turn, help chemists
to further optimize the reaction conditions and to construct
more organoantimony complexes with novel topologies or
higher bioactivity.
[7]
drawing groups for higher bioactivity performance as sup-
porting ligands to construct organoantimony derivatives. As
expected, three tetranuclear organoantimony compounds with
molecular structures similar to compounds reported previously
were prepared, which could be able to play an important role
in exploring the relationship between the number of nuclei and
4]
[8]
bioactivity performance. Herein, the syntheses and the crys-
tal structures of these compounds are reported, the bioactivity
screening experiment is ongoing in our group and the results
will be reported later.
It is well-known that organoantimony salts used to construct
organoantimony complexes are mostly surrounded by tri- or
tetra-organo groups, and owing to bulk and steric hindrance,
Results and Discussion
Synthesis
*
Prof. Dr. H. Yin
According to the documented method, biphenylantimony tri-
chloride was synthesized and reacted with carboxylic acids in
Fax: +86-6358239121
E-Mail: handongyin@lcu.edu.cn
[
a] Shandong Provincial Key Laboratory of Chemical Energy Storage an atmosphere of dry nitrogen using standard Schlenk tech-
and Novel Cell Technology
niques. Three organoantimony derivatives from carboxylic ac-
ids were obtained and crystals suitable for X-ray crystallo-
graphic investigations were obtained by recrystallizing from
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 725
School of Chemistry and Chemical Engineering
Liaocheng University
Liaocheng 252059, P. R. China
Z. Anorg. Allg. Chem. 2012, 638, (5), 725–729

H. Yin, Q. Wu, M. Hong, W. Li
ARTICLE
different organic solvents (Scheme 1, for the details see Exper- NMR Spectroscopy
imental Section).
1
In the H NMR spectra of compounds 1, 2, and 3, no signal
resonance of COOH is observed, which suggests that the car-
boxyl group is deprotonated and coordinates to the central anti-
mony atom. The NMR spectra of the compounds show that the
chemical shifts of the protons on the aryl group were assigned
reasonably. In the 13C NMR spectra of the title compounds,
the signal derived from the carboxylate group is observed in
the range from 168 to 193 ppm. Besides, co-crystallized sol-
vent molecules can also be assigned reasonably and the NMR
spectroscopic data are in good agreement with the crystal
structure.
Structure Description
The three title compounds have similar molecular structures,
which are shown in Figure 1, Figure 2, and Figure 3. Selected
bonds lengths and angles are listed in Table 1 whereas the most
relevant crystallographic data are listed in Table 2. Herein we
just take compound 1 as an example, whereas for antimony
Scheme 1. Synthesis procedures for the title compounds.
IR Spectroscopy
In the FT-IR spectra, bands at 1535 to 1555 and 1425 to atoms we take Sb(1) as example, because of the analogue coor-
–
1
1
440 cm are assigned to ν
(CO ) and ν (CO ) respec- dination environment of every antimony atom in compounds
asym 2 sym 2
1
–
tively and Δν = 95–130 cm , thus carboxyl groups coordinate 1–3. According to Figure 1, it is obvious that every antimony
to the metal atom in a bidentate mode, which are also sup- atom is hexacoordinate and the arrangement is best described
ported by the C–O bond lengths (Table 1). A strong band at as distorted octahedral, with two oxygen atoms in the axial
89–795 cm shows the presence of Sb–O–Sb stretching, position and two carbon atoms from phenyl groups together
whereas Sb–O absorption can be found at 450–480 cm , with two oxygen atoms occupying the equatorial plane. The
–
1
7
–1
which are in accordance with the crystal structure. All the trans angle between two axial oxygen atoms is in the range
bands observed are consistent with the data in the earlier litera- between 171–178°, just slightly deviating from the linear angle
ture.[
8]
180°.
Table 1. Selected bond lengths /Å and angles /° for complexes 1–3.
1
Sb(1)–O(7)
Sb(1)–O(10)
Sb(1)–C(23)
Sb(1)–Sb(2)
1.919(10)
2.084(10)
2.106(17)
3.2128(14)
1.253(18)
94.8(6)
Sb(1)–O(9)
Sb(1)–C(17)
Sb(1)–O(1)
O(1)–C(1)
O(9)–Sb(1)–O(10)
O(10)–Sb(1)–C(23)
O(7)–Sb(1)–O(1)
Sb(1)–O(10)–Sb(2)
2.010(10)
2.089(17)
2.200(10)
1.238(18)
74.6(4)
89.6(5)
175.0(4)
100.5(4)
O(2)–C(1)
O(9)–Sb(1)–C(17)
C(17)–Sb(1)–C(23)
Sb(1)–O(7)–Sb(3)
99.2(7)
141.5(6)
2
Sb(1)–O(9)
Sb(1)–O(6)
Sb(1)–C(21)
Sb(1)–Sb(2)
1.936(6)
2.079(6)
2.142(10)
3.2508(9)
1.269(11)
91.1(3)
Sb(1)–O(5)
Sb(1)–C(15)
Sb(1)–O(1)
O(1)–C(1)
O(5)–Sb(1)–O(6)
O(5)–Sb(1)–C(21)
O(9)–Sb(1)–O(1)
Sb(1)–O(9)–Sb(4)
2.019(6)
2.136(9)
2.291(6)
1.247(11)
75.9(2)
93.6(3)
175.0(2)
141.0(3)
O(2)–C(1)
O(6)–Sb(1)–C(15)
C(15)–Sb(1)–C(21)
Sb(1)–O(5)–Sb(2)
97.4(4)
106.4(3)
3
Sb(1)–O(10)
Sb(1)–O(6)
Sb(1)–C(17)
Sb(1)–Sb(2)
1.929(6)
2.068(6)
2.132(8)
3.2403(8)
1.268(9)
91.7(3)
Sb(1)–O(5)
Sb(1)–C(23)
Sb(1)–O(1)
O(1)–C(1)
O(5)–Sb(1)–O(6)
O(6)–Sb(1)–C(17)
O(10)–Sb(1)–O(1)
Sb(4)–O(10)–Sb(1)
2.030(5)
2.121(10)
2.207(6)
1.250(10)
75.5(2)
89.1(3)
176.8(2)
148.6(3)
O(2)–C(1)
O(5)–Sb(1)–C(23)
C(23)–Sb(1)–C(17)
Sb(1)–O(5)–Sb(2)
102.4(4)
104.9(2)
7
26
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 725–729

“Cage-like” Carboxyl Bridged Octaphenyltetraantimony Compounds
The Sb–O bonds in the molecule are in the range between
.91 and 2.20 Å, whereas the Sb–O bond lengths reported in
1
[1b,4b,9]
literature are larger than 2.00 Å.
The shortest are those
associated with monodentately bridging oxygen atoms [i.e.
O(7)], which are in agreement with the above angle data. The
longest are those bonded to the oxygen atoms of carboxyl
groups, but every two Sb–O bonds in the same carboxyl group
are nearly equal, which indicates almost complete delocaliza-
tion of the π electrons. The distance between Sb(1) and Sb(2)
is 3.2128(14) Å, which is longer than the sum of the covalent
radii but much shorter than the sum of the van der Waals radii,
and there exists strong interaction between the two antimony
atoms.[ Instead of a tetra-bridged structure, the products ex-
hibit a (SbPh ) (μ-O) (μ-OH) “cage” structure, which is pre-
10]
2
4
4
2
Figure 1. Molecular structure of complex 1 (the uncoordinated solvent
molecules and hydrogen atoms are omitted for clarity).
ferred to the tetra-bridged product, (SbPh ) (μ-O) (μ-O CR) ,
2 2 2 2 2
and can be rationalized: such tetra-bridged compounds would
be strained from the short “bite” of the carboxyl group, but
when only one carboxyl-bridge is present, the strain will be
relieved and the axial angles are close to linearity.
The three title compounds co-crystallize with different sol-
vent molecules, one water molecule and a quarter of a diethyl
ether molecule for 1, one water molecule and two diethyl ether
molecules for 2 and one ethanol molecule for 3, but they exhi-
bit similar molecular structures. This implies that the nature of
the solvent molecule does not exert great influence on the
overall structural topology.[
11]
Conclusions
Figure 2. Molecular structure of complex 2 (the uncoordinated solvent
molecule and hydrogen atoms are omitted for clarity).
According to the documented method, biphenylantimony tri-
chloride was synthesized. As expected, through reduction of
the number of organo-group, the bulk and the steric hindrance
were relieved and tetranuclear organoantimony complexes
with Sb O6 “cage” structure derived from carboxylic acids
4
were obtained. Although different carboxylic acids were cho-
sen, a similar structure was obtained in all three cases, which
indicates the extensive applicability of the synthesis method
and the stability of the “cage” structure. Together with other
mono- and dinuclear organoantimony compounds, the title
complexes will play an important role in exploring the rela-
tionship between the number of nuclei and bioactivity perform-
ance. Herein, the synthesis method and the crystal structure are
reported, the bioactivity screening experiment is ongoing in
our group and the results will be reported later.
Figure 3. Molecular structure of complex 3 (the uncoordinated solvent
molecule and hydrogen atoms are omitted for clarity).
Experimental Section
A pair of antimony atoms is bridged by a carboxyl group,
2 4 4 2 2 6 3 2
an oxygen atom and a hydroxyl oxygen atom to form a Sb O2 Synthesis of (SbPh ) (μ-O) (μ-OH) [μ-O C-(2-CHO-C H )] (1):
2
The reaction was carried out in an atmosphere of nitrogen by using
standard Schlenk techniques. 2-Aldehyde benzoic acid (60 mg,
four-membered ring. Due to the bulk and steric effect of the
phenyl group, the angle of O(9)–Sb(1)–O(10) is only 74.6(4)°,
and the angle of C(17)–Sb(1)–C(23) is 99.2(7)° (Figure 1).
Two oxygen atoms interlink two four-membered rings on both
sides, forming a Sb O cage-like conformation. It should be
0.4 mmol) and triethylamine (40.5 mg, 0.4 mmol) were solved in benz-
ene (40 mL) solution and stirred for 0.5 h. Afterwards, biphenylanti-
mony trichloride (169.6 mg, 0.4 mmol) was added to the mixture, and
the reaction was allowed to continue for 8 h at room temperature. After
filtration, the solvents were evaporated in vacuo. The obtained solid
was recrystallized from diethyl ether/petroleum ether (1:1).Yield 75%,
4
6
noted that the angles involving the single oxo bridges [i.e.
Sb(1)–O(7)–Sb(3)] are between 140–145° whereas the angles
in the Sb O ring [i.e. Sb(1)–O(10)–Sb(2)] are in the range m.p. 192–194 °C. Anal. C260H226O53 Sb16 (6146.41): calcd. C 50.8; H
2
2
1
04–106°.
3.71%; found C 51.15; H 3.82%. IR (KBr): ν˜ = 1538 νas(CO
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.zaac.wiley-vch.de
2
), 1429
Z. Anorg. Allg. Chem. 2012, 725–729
727

H. Yin, Q. Wu, M. Hong, W. Li
ARTICLE
Table 2. Crystal data and structure refinement parameters for complexes 1–3.
1
2
3
Empirical formula
C
260
H
226
O53 Sb16
C
70
H
70
F
4
O13 Sb
4
136 122 12 8
C H F O23Sb
Formula weight
Wavelength /Å
Crystal system
Space group
a /Å
b /Å
c /Å
α /°
β /°
6146.41
0.71073
1682.26
0.71073
3326.34
0.71073
triclinic
monoclinic
P2 /c
monoclinic
P2 /c
19.619(2)
¯
1
1
P1
19.835(2)
16.8628(18)
21.298(2)
90
90.386(2)
90
7123.4(14)
1
12.0161(13)
15.2652(16)
19.314(2)
83.108(2)
76.7670(10)
80.664(2)
3390.3(6)
1
16.3154(19)
16.3154(19)
90
90.112(2)
90
6997.3(13)
4
1.597
γ /° 3
V /Å
Z
–3
Dcalc /Mg·m
1.433
1.555
1.629
1.651
–1
μ /mm
1.598
F(000)
3026
3336
1638
Crystal size /mm
Reflections collected
Unique reflections [Rint
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [IϾ2σ (I)]
R indices (all data)
0.21ϫ0.19ϫ0.18
36087
12554 [R(int) = 0.1680]
12554 / 1422 / 775
0.893
0.49ϫ0.40ϫ0.22
35480
12260 [R(int) = 0.0404]
12260 / 2423 / 839
1.164
0.44ϫ0.24ϫ0.15
17498
11613 [R(int) = 0.0200]
11613 / 0 / 1078
1.133
]
R
1
= 0.1040, wR
= 0.1852, wR
2
= 0.2471
= 0.2901
R
1
= 0.0507, wR
= 0.1073, wR
2
= 0.0953
= 0.1313
R
1
= 0.0456, wR
= 0.0997, wR
2
= 0.0936
= 0.1302
R
1
2
R
1
2
R
1
2
–1
ν
(
s
(CO
400 MHz, CDCl
H, Ph-H), 3.12 (m, 1 H, OCH
100 MHz, CDCl , 25 °C): δ = 192.96, 170.43, 127.80, 128.84, 129.11,
29.94, 130.02, 130.58, 131.64, 131.92, 132.97, 133.84, 134.07,
35.55, 136.47, 137.05, 137.55, 77.57, 77.25, 46.94, 45.85, 8.79 ppm.
2
), 790 (Sb–O–Sb), 465 (Sb–C), 481 (Sb–O) cm . 1H NMR
numbers CCDC-841760 (1), CCDC-841761 (2), and CCDC-841762
(3) (Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk,
http://www.ccdc.cam.ac.uk).
3
, 25 °C): δ = 10.23 (s, 2 H, CHO), 7.06–7.81 (m, 48
1
3
2
2 3
–), 1.31 (1.5 H, t, OCH CH ). C NMR
(
1
1
3
Acknowledgment
We acknowledge the National Natural Science Foundation of China
2 4 4 2 2 2 6 3 2
Synthesis of (SbPh ) (μ-O) (μ-OH) [μ-O C-(2,3-F -C H )] (2):
(
201105042), the National Basic Research Program (2010CB234601),
and the Natural Science Foundation of Shandong Province
ZR2011BM007, ZR2010BQ021) for financial support. Additionally,
The synthesis procedure was the same as applied for 1 with the excep-
tion that 2,3-difluorobenzoic acid was used instead of 2-aldehyde ben-
zoic acid. The colorless solid was recrystallized from petroleum ether/
(
this work was supported by Shandong Tai-shan Scholar Research
Fund.
70 4 4
ethyl ether (1:1). Yield 74%, m.p. 184–186 °C. Anal. C70H F O13Sb
(
(
1682.26): calcd. C 49.98; H 4.19%; found C 50.02; H 4.12%. IR
KBr): ν˜ = 1533 νas(CO ), 1425 ν (CO ), 794 (Sb–O–Sb), 455 (Sb–
, 25 °C): δ = 7.15–
.35 (m, 40 H, Sb-PhH), 6.99–7.01 (m, 6 H, Ph-H), 3.14 (m, 8 H,
2
s
2
–1 1
C), 484 (Sb–O) cm . H NMR (400 MHz, CDCl
7
OCH
3
References
1
3
2
–) 1.42 (t, 12 H, OCH
2
CH
3
). C NMR (100 MHz, CDCl
3
,
[1] a) L. Quan, H. Yin, J. Cui, M. Hong, D. Wang, J. Organomet.
Chem. 2009, 694, 3708–3717; b) H. Yin, L. Quan, L. Li, Inorg.
Chem. Commun. 2008, 11, 1121–1124; c) M. Chovancová, R.
Jambor, A. R u˚ zˇ i cˇ ka, R. Jirásko, I. Císa rˇ ová, L. Dosatál, Organo-
metallics 2009, 28, 1934–1941; d) L. Dostál, R. Jambor, R. Jirá-
sko, Z. Pad eˇ Iková, A. R u˚ zˇ i cˇ ka, J. Hole cˇ ek, J. Organomet. Chem.
2
1
5 °C): δ = 168.6, 137.00, 134.21, 133.86, 133.56, 131.71, 129.82,
28.21, 127.28, 77.56, 77.24, 76.93, 46.11, 8.80 ppm.
2 4 4 2 2 3 6 3 2
Synthesis of (SbPh ) (μ-O) (μ-OH) [μ-O C-(4-CF –C H )] (3):
The synthesis procedure was the same as applied for 1 with the excep-
tion that 4-trifluoromethylbenzoic acid was used instead of 2-aldehyde
benzoic acid. The colorless solid was recrystallized from ethanol/ethyl
ether (1:1). Yield 78%, m.p. 188–189 °C. Anal. C136H F O23Sb
122 12 8
(
2
010, 695, 392–397; e) L. Dostál, R. Jambor, I. Císa rˇ ová, L. Be-
ne sˇ , A. R u˚ zˇ i cˇ ka, R. Jirásko, J. Hole cˇ ek, J. Organomet. Chem.
007, 692, 2350–2353.
2
[
2] J. Xia, R. Qiu, S. Yin, X. Zhang, S. Luo, C.-T. Au, K. Xia, W.-
3326.34): calcd. C 49.11; H 3.70%; found C 49.22; H 3.56%. IR
KBr): ν˜ = 1549 νas(CO2), 1432 ν
(CO2), 793 (Sb-O-Sb), 451 (Sb-C), [3] a) H.-J. Zhao, L.-H. Li, L.-M. Wu, L. Chen, Inorg. Chem. 2010,
s
Y. Wong, J. Organomet. Chem. 2010, 695, 1487–1492.
(
4
–1 1
77 (Sb-O) cm . H NMR (400 MHz, CDCl
3
, 25 °C) : δ = 6.83–6.95
49, 5811–5817; b) V. Jo, M. K. Kim, D. W. Lee, I.-W. Shim,
K. M. Ok, Inorg. Chem. 2010, 49, 2990–2995.
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Wang, F. Ran, J. Organomet. Chem. 2005, 690, 151–156; b) G.
Wang, J. Xiao, L. Yu, J. Li, J. Cui, R. Wang, F. Ran, J. Or-
ganomet. Chem. 2004, 689, 1631–1638; c) N. C. Kasuga, K. Ono-
dera, S. Nakano, K. Hayashi, K. Nomiya, J. Inorg. Biochem.
(m, 8 H, Ph–H), 7.19–7.35 (m, 40 H, Sb–PhH), 3.71 (t, 2 H, –CH
2
–
[
Me), 3.18 (m, 2 H, OCH –), 9.10 (s, 1 H, EtOH), 1.23 (t, 3 H, CH
2
3
),
). 1 C NMR (100 MHz, CDCl3, 25 °C): δ =
2 3
.45 (t, 3 H, OCH CH
3
1
1
1
68.9, 137.39, 136.19, 133.9, 133.46, 131.76, 130.68, 130.43, 129.88,
29.54, 128.27, 125.32, 125.29, 77.57, 77.25, 76.93, 66.11 ppm.
2
006, 100, 1176–1186.
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
[
5] L. Quan, H. Yin, J. Cui, M. Hong, L. Cui, M. Yang, D. Wang, J.
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7
28
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 725–729

“Cage-like” Carboxyl Bridged Octaphenyltetraantimony Compounds
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www.zaac.wiley-vch.de
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