A STUDY OF CRYSTAL STRUCTURES OF TETRA(p-TOLYL)ANTIMONY 2,4,6-TRICHLOROPHENOXIDE AND 3,4,5-TRIFLUOROBENZOATE

Article abstract of DOI:10.1134/S0022476620090085

Abstract: Tetra(p-tolyl)antimony 2,4,6-trichlorophenoxide p-Tol₄SbOC₆H₂Cl₃-2,4,6 (1) and tetra(p-tolyl)antimony 3,4,5-trifluorobenzoate p-Tol₄SbOС(O)C₆H₂F₃-3,4,5 (2) are synthesized by the interaction of penta(p-tolyl)antimony with equimolar amounts of 2,4,6-trichlorophenol and 3,4,5-trifluorobenzoic acid in a benzene solution. Compounds 1 and 2 are also obtained by ligand redistribution reactions between penta(p-tolyl)antimony and symmetric antimony derivatives p-Tol₃SbХ₂. The crystal structures and structural features of compounds 1 and 2, in which antimony atoms have a trigonal bipyramidal coordination of substituents with axially located oxygen-containing ligands, are determined by single crystal X-ray diffraction.

Full text of DOI:10.1134/S0022476620090085

ISSN 0022-4766, Journal of Structural Chemistry, 2020, Vol. 61, No. 9, pp. 1414-1421. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Strukturnoi Khimii, 2020, Vol. 61, No. 9, pp. 1490-1497.
A STUDY OF CRYSTAL STRUCTURES
OF TETRA(p-TOLYL)ANTIMONY
2,4,6-TRICHLOROPHENOXIDE
AND 3,4,5-TRIFLUOROBENZOATE
1 1
V. V. Sharutin , O. K. Sharutina ,
1
and A. N. Efremov *
Tetra(p-tolyl)antimony 2,4,6-trichlorophenoxide p-Tol4SbOC6H2Cl3-2,4,6 (1) and tetra(p-tolyl)antimony
3,4,5-trifluorobenzoate p-Tol4SbOС(O)C6H2F3-3,4,5 (2) are synthesized by the interaction of
penta(p-tolyl)antimony with equimolar amounts of 2,4,6-trichlorophenol and 3,4,5-trifluorobenzoic acid in
a benzene solution. Compounds 1 and 2 are also obtained by ligand redistribution reactions between
penta(p-tolyl)antimony and symmetric antimony derivatives p-Tol3SbХ2. The crystal structures and
structural features of compounds 1 and 2, in which antimony atoms have a trigonal bipyramidal
coordination of substituents with axially located oxygen-containing ligands, are determined by single
crystal X-ray diffraction.
DOI: 10.1134/S0022476620090085
Keywords: tetra(p-tolyl)antimony 2,4,6-trichlorophenoxide, tetra(p-tolyl)antimony 3,4,5-trifluorobenzoate,
synthesis, crystal and molecular structures.
INTRODUCTION
Pentavalent antimony compounds with the general formula Ar4SbX (where X is a ligand bonded to the antimony
atom via a heteroatom) have been structurally characterized sufficiently well [1-23]. Tetraphenylantimony carboxylates and
aroxides are most well studied in the wide range of these derivatives [24-37]. These compounds are synthesized by
substitution reactions between acids (phenols) and pentaphenylantimony [24, 25, 27, 28] or tetraphenylantimony halide in the
presence of a hydrogen halide acceptor [29-36]. A method based on reactions of tetraphenylantimony halide with acid salts
has been known, too [37]. Synthesis by the ligand redistribution reaction between pentaphenylantimony and a derivative with
the symmetric structure Ph3SbX2 is less popular [26]. Note that data on the synthesis and structure of tetra(p-tolyl)antimony
derivatives over the last five years were given only in [38, 39].
This work is devoted to the synthesis and crystal structure studies of tetra(p-tolyl)antimony 2,4,6-trichlorophenoxide
p-Tol4SbOC6H2Cl3-2,4,6 (1) and tetra(p-tolyl)antimony 3,4,5-trifluorobenzoate p-Tol4SbOС(O)C6H2F3-3,4,5 (2).
1
South Ural State University, Chelyabinsk, Russia; *efremov_an94@mail.ru. Original article submitted February 20,
2020; revised April 7, 2020; accepted April 16, 2020.
1414
0022-4766/20/6109-1414 © 2020 by Pleiades Publishing, Ltd.

EXPERIMENTAL
General synthesis procedure. The starting reagent (penta(p-tolyl)antimony) was obtained by the procedure
described in [40]. In the work, we used 2,4,6-trichlorophenol and 3,4,5-trifluorobenzoic acid (Alfa Aesar). In the first case,
compound 1 was synthesized by the interaction of 0.346 mmol of penta(p-tolyl)antimony with 0.346 mmol of 2,4,6-
trichlorophenol in 2 mL of benzene in a sealed ampoule. After heating the ampoule for 1 h at 80 °С and subsequent slow
cooling colorless crystals of 1 were isolated from the reaction mixture (yield 91%, Тmelt 188 °С). In the second case, 1 was
obtained from 0.346 mmol of penta(p-tolyl)antimony and 0.346 mmol of tris(p-tolyl)antimony bis(2,4,6-trichlorophenoxide)
in 2 mL of benzene by the similar procedure (yield 90%, Тmelt 188 °С).
The IR spectrum was measured on a Shimadzu IRAffinity-1S IR-Fourier spectrometer in KBr pellets in the range
–1
4000-400 cm . The С, Н elemental analysis was conducted on a Carlo-Erba 1106 instrument.
Found for 1 (%): С 59.73, Н 4.51; calculated for C34H30OCl3Sb (%): С 59.81, Н 4.44.
–1
IR spectrum (ν, cm ): 3111, 3059, 3024, 3012, 2974, 2954, 2918, 2864, 1639, 1591, 1560, 1527, 1492, 1452, 1440,
1419, 1388, 1307, 1298, 1273, 1247, 1230, 1211, 1188, 1178, 1116, 1062, 1037, 1012, 972, 947, 869, 854, 796, 740, 700,
678, 634, 582, 572, 489, 426, 403.
TABLE 1. Crystallographic Data and Conditions of the Diffraction Experiment for 1 and 2
Parameter
1
2
Stoichiometric formula
М
C34H30OCl3Sb
682.68
C35H30O2F3Sb
661.34
Crystal system
Space group
a, b, c, Å
Monoclinic
P21/n
Triclinic
P1
11.787(8), 17.357(13),15.897(14) 10.276(8), 11.619(10), 14.120(9)
90.00, 103.15(4), 90.00
75.95(4), 88.93(4), 70.97(4)
α, β, γ, deg
3
V, Å
3167(4)
4
1543(2)
2
Z
3
1.432
1.424
ρcalc, g/cm
–1
1.149
0.941
μ, mm
F(000)
1376.0
668.0
Crystal dimensions, mm
0.26×0.25×0.07
from 5.88 to 54.3
0.38×0.36×0.25
from 6.56 to 71.74
2θ range of data collection, deg
Index range
–15 ≤ h ≤ 15,
–22 ≤ k ≤ 22,
–20 ≤ l ≤ 20
41724 / 6980
[Rint = 0.0484]
0.994
–16 ≤ h ≤ 16,
–19 ≤ k ≤ 19,
–23 ≤ l ≤ 23
109386 / 14259
[Rint = 0.0444]
0.985
Number of measured / unique reflections
Data collection completeness over θ = 25.00°,%
Refinement method
2
2
Full-matrix LSM on F
Full-matrix LSM on F
Number of reflections / restraints / parameters
6980 / 0 / 356
1.028
14259 / 0 / 374
1.043
2
S-factor on F
R1 = 0.0302,
wR2 = 0.0629
R1 = 0.0500,
wR2 = 0.0702
−0.57 and 0.39
R1 = 0.0446,
wR2 = 0.0838
R1 = 0.0835,
wR2 = 0.0954
−0.55 and 0.64
R-factor [I > 2σ(I)]
R-factor (all data)
3
Residual electron density (min and max), e/Å
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Compound 2 was obtained similarly. Yield 90%, Тmelt 182 °С.
Found for 2 (%): С 63.49, Н 4.63; calculated for C35H30O2F3Sb (%): С 63.56, Н 4.58.
–1
IR spectrum (ν, cm ): 3074, 3034, 3016, 2922, 2866, 1637, 1616, 1593, 1564, 1521, 1492, 1433, 1394, 1355, 1296,
1273, 1226, 1211, 1190, 1178, 1116, 1093, 1064, 1043, 1016, 970, 952, 894, 846, 831, 798, 783, 756, 732, 711, 700, 638,
582, 574, 551, 489, 480, 445.
X-ray experiments were carried out on a D8 Quest Bruker diffractometer (MoK radiation, λ = 0.71073 Å, graphite
α
monochromator) at 293(2) K. Data collection and editing, refinement of unit cell parameters, and absorption correction were
performed using SMART and SAINT-Plus programs [41]. All structure calculations and refinement were carried out using
the SHELXL/PC [42] and Olex2 [43] programs. The structures were solved by a direct method and refined by the least
squares technique in the anisotropic approximation for non-hydrogen atoms. Positions of hydrogen atoms were calculated
geometrically and included in the refinement in the riding model. Full tables of atomic coordinates, bond lengths and bond
angles have been deposited with the Cambridge Crystallography Data Center (Nos. 1957182 (1), 1978214 (2);
deposit@ccdc.cam.ac.uk; http://www.ccdc.cam.ac.uk). Main crystallographic data and refinement results for structures 1 and
2 are summarized in Table 1; selected bond lengths and bond angles are listed in Table 2.
TABLE 2. Selected Bond Lengths and Bond Angles in the Structures of 1 and 2
Bond
d, Å
Angle
ω, deg
1
Sb1–O1
Sb1–C1
Sb1–C11
Sb1–C31
Sb1–C21
O1–C41
Cl3–C46
Cl2–C44
Cl1–C42
C4–C7
2.266(2)
2.121(3)
2.118(3)
2.125(3)
2.173(3)
1.316(3)
1.737(3)
1.751(3)
1.727(3)
1.521(5)
1.528(5)
C1–Sb1–O1
C1–Sb1–C31
C1–Sb1–C21
C11–Sb1–O1
C11–Sb1–C1
C11–Sb1–C31
C11–Sb1–C21
C31–Sb1–O1
C31–Sb1–C21
C21–Sb1–O1
C41–O1–Sb1
83.29(10)
111.10(10)
95.10(11)
83.35(8)
128.33(10)
117.17(11)
96.49(10)
85.28(10)
96.77(11)
177.76(8)
130.46(15)
C14–C17
2
Sb1–O1
Sb1–C1
Sb1–C21
Sb1–C41
Sb1–C11
O1–C37
O2–C37
C35–F3
C33–F1
F2–C34
C4–C7
2.294(2)
2.123(3)
2.118(2)
2.157(2)
2.114(2)
1.293(2)
1.218(3)
1.344(3)
1.347(4)
1.345(3)
1.533(4)
1.518(3)
C1–Sb1–O1
C1–Sb1–C41
C21–Sb1–O1
C21–Sb1–C1
C21–Sb1–C41
C41–Sb1–O1
C11–Sb1–O1
C11–Sb1–C1
C11–Sb1–C21
C11–Sb1–C41
C37–O1–Sb1
O2–C37–O1
85.32(8)
92.68(9)
84.32(9)
126.86(8)
96.18(9)
177.80(6)
82.57(7)
116.48(9)
113.53(8)
99.17(8)
122.17(13)
126.40(18)
C24–C27
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RESULTS AND DISCUSSION
Compounds 1 and 2 were synthesized by the interaction of penta(p-tolyl)antimony with phenol or acid in benzene
(Scheme 1)
Scheme 1. Synthesis of compounds 1 and 2.
Derivatives of 1 and 2 were also obtained by the ligand redistribution reaction between penta(p-tolyl)antimony and
a derivative with the symmetric structure p-Tol3SbX2 in a benzene solution
p-Tol5Sb + p-Tol3SbX2 → 2 p-Tol4SbX
X = OC6H2Cl3-2,4,6 (1), OC(O)C6H2F3-3,4,5 (2).
Both syntheses are characterized by a high yield and the purity of the target product.
To study the structures of the compounds IR spectroscopy and single crystal X-ray diffraction (XRD) were
employed.
–1
The IR spectra of compounds 1 and 2 exhibit an intense absorption band at 489 cm that characterizes vibrations of
–1
Sb–C bonds. An absorption band at 1298 cm corresponds to stretching vibrations of C–О bonds in the IR spectrum of
–1
compound 1. The 740 cm band that is located in a higher frequency range compared to the similar band in the IR spectrum
–1
of 2,4,6-trichlorophenol (732 cm ) may be assigned to vibrations of С–Cl bonds. An intense absorption band at 1637 cm
–1
–1
characterizes the carbonyl group in the spectrum of compound 2. Absorption bands in the range 3111-3012 cm belong to
vibrations of CAr–H bonds in aryl, phenoxide, and carboxylate ligands. The bands of stretching vibrations of methyl groups of
–1 –1
p-tolyl substituents are also observed: asymmetric vibrations at 2918 cm (1), 2922 cm (2), symmetric vibrations at
–1 –1
2864 cm (1), 2866 cm (2) [44].
According to the data of the single crystal XRD analysis, in the molecules of 1 and 2 the antimony atoms have
a distorted trigonal bipyramidal coordination with axially located aroxide and carboxylate ligands respectively (Figs. 1, 2).
The СSbO axial angles are 177.76(8)° (1), 177.80(6)° (2); the sums of СSbС angles in the equatorial plane are
356.6(10)° (1), 356.87(8)° (2). The values of ОaxSbCeq angles are less than 90° while those of СaxSbCeq are larger than 90°.
Antimony atoms are out of the [C3] equatorial plane towards the axial carbon atom by 0.225 Å (1) and 0.216 Å (2). All bond
angles at antimony atoms in the molecules of 1 and 2 have similar values. The Sb–Ceq bond lengths in the molecules are also
1417

Fig. 1. General view of the molecule of compound 1 (hydrogen atoms are
omitted).
Fig. 2. General view of the molecule of compound 2
(hydrogen atoms are omitted).
approximately the same (2.121(3) Å, 2.118(3) Å, 2.125(3) Å (1) and 2.123(3) Å, 2.118(2) Å, 2.114(2) Å (2)). A distinction is
observed in Sb–Cax distances, which is 0.016 Å larger in 1 than 2. On the contrary, the Sb–O distance is 0.028 Å larger in the
molecule of 2 than that in 1. An increase in Sb–O distances in comparison with the sum of covalent radii of antimony and
oxygen (2.07 Å), which is observed in the molecules of tetraarylantimony aroxides and carboxylates [24-37], indicates the
coordination character of this bond [38, 39]. The increase in the Sb–O distance in 2 can be explained by a lower basicity of
the carboxylate anion in comparison with the basicity of the aroxide anion, and hence, its lower coordination ability.
A feature is revealed in the arrangement of equatorial aryl groups in the molecule of 1. Thus, two aryl rings ([C1–
C6] and [C31–C36]) in the structure are turned about the equatorial Sb–C bonds so that the angles between their planes and
1418

Fig. 3. Scheme of the molecular interaction of one crystallographic
cell of compound 1.
the equatorial [C1C11C31] plane are 57.27° and 68.94° respectively, whereas a similar angle with the plane of the third
aromatic ring [C11–C16] is only 13.38°. This ring is located opposite to the C41–C46 aromatic ring plane of the aroxy group,
which determines the interaction of their π systems. However, the ideal geometry of this π–π stacking interaction is distorted:
the interplanar angle is 38.72°, the distance between the centers of π systems of the aroxide and p-tolyl ligands is 4.01 Å.
Similar interactions are also observed in other tetraarylantimony aroxides [24, 25, 36, 38].
A characteristic feature of tetraarylantimony carboxylates is the presence of the intramolecular contact of the
antimony atom with the carbonyl oxygen atom [26-37, 39]. In the structure of compound 2, the Sb⋯O=C distance is
3.377(3) Å, which is smaller than the sum of van der Waals radii of antimony and oxygen atoms (3.70 Å) [45]. This
interaction causes an increase in one of the equatorial C(1)SbC(21) angles (126.86(8)°) located from the side of the
intramolecular contact.
The structures of the crystals of compounds 1 and 2 are organized by weak halogen–hydrogen hydrogen bonds of
Cl2⋯Н–C22 (2.94 Å) (1) and F2⋯Н–C17 (2.47 Å) (2) types and C–H π-interactions.
The crystal of compound 1 also contains intermolecular Cl⋯Cl contacts between two molecules of one
crystallographic cell (Z = 4) (Fig. 3). The two types of dimers formed alternate along the [abc ] parallelepiped diagonal.
The Cl⋯Cl distances are shorter than the sum of van der Waals radii of chlorine atoms (3.60 Å) and are 3.32 Å,
which evidences the occurrence of halogen⋯halogen interactions. All С–Cl⋯Cl angles at chlorine atoms are the same
(146.92(9)°) because these interactions are observed only between symmetrically equivalent chlorine atoms bound by the
center of inversion. The halogen⋯halogen interaction corresponds to type I characterized by similar or equal values of angles
around halogen atoms [46].
Thus, in this work on substitution and ligand redistribution reactions, tetra(p-tolyl)antimony 2,4,6-
trichlorophenoxide and 3,4,5-trifluorobenzoate are obtained with a high yield and structurally characterized. The
coordination polyhedron of the antimony atom in both compounds is a distorted trigonal bipyramid with an axially located
oxygen-containing ligand. In the crystal of tetra(p-tolyl)antimony 2,4,6-trichlorophenoxide there are not only weak hydrogen
bonds but also short halogen⋯halogen contacts.
CONFLICT OF INTERESTS
The authors declare that they have no conflict of interests.
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