J. Braz. Chem. Soc., Vol. 8, No. 6, 649-652, 1997.
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Article
Adduct Formation Between Diphenyltin Dichloride and
2-phenyl-1,3-dithiane trans-1-trans-3-dioxide. Preparation,
Spectroscopy, Crystal and Molecular Structure of
[Ph2SnCl2.CH2(CH2)2SOCH(Ph)SO]
Gerimário F. de Sousaa, Carlos A.L. Filgueirasb*, John F. Nixonc,
and Peter B. Hitchcockc
a
Departamento de Química, ICC, Universidade de Brasília,
70919-900 Brasília - DF, Brazil
b
Departamento de Química, ICEx, Universidade Federal de Minas Gerais,
31270-901 Belo Horizonte - MG, Brazil
c
School of Chemistry and Molecular Sciences, University of Sussex,
Brighton, BN1 9QJ, UK
Received: April 18, 1997
Um novo aduto pentacoordenado de Sn (IV) foi preparado a partir de dicloreto de difenilestanho
(IV) e do dissulfóxido 2-fenil-1,3-ditiano trans-1,trans-3-dióxido. O estudo espectroscópico e por
difração de raios-X mostrou ser o novo composto um exemplo raro de aduto pentacoordenado 1:1
entre uma espécie organometálica de Sn (IV) e um ligante neutro. Apesar de ser difuncional, o ligante
apresenta-se monodentado, em virtude de sua geometria peculiar. Ademais, o aduto não mostra
evidência de interação intermolecular forte, formando moléculas discretas.
A new pentacoordinate Sn (IV) adduct was prepared from diphenyltin (IV) dichloride and the
disulphoxide 2-phenyl-1,3-dithiane trans-1, trans-3-dioxide. Spectroscopic and X-ray diffraction
studies showed the new compound to be a rare example of a pentacoordinate 1:1 adduct between
an organometallic Sn (IV) species and a neutral ligand. In spite of being difunctional, the ligand is
monodentate as a result of its peculiar geometry. Moreover, the adduct does not show any evidence
of strong intermolecular interactions, forming discrete molecules.
Keywords: Sn (IV) adduct, tin organometallics, tin-disulphoxide adduct
Introduction
Most 1:1 adducts of diorganotin (IV) dihalides with
Lewis donor ligands are actually six-coordinate dimeric
species, in particular when the organic group is methyl1.
Only a few adducts of this type are truly pentacoordinate2,
such as that formed between diphenyltin (IV) dichloride
with benzothiazole2, and those between both diphenyltin
(IV) dichloride and trimethyltin (IV) chloride with 2,6-dimethylpyridine3, as well as that which occurs between
dimethyltin (IV) dichloride and dibenzylsulphoxide4. A
curious example is given by the pyrazine adducts with
dimethyltin (IV) dichloride and diphenyltin (IV) dichloride. Both cases produce polymeric chains in which the
ligand and the organotin moiety alternate. The first of these
adducts has a structure made up exclusively of six-coordinate tin atoms in the chains. The second, however, forms
alternating chains containing five- and six-coordinate tin
centres, respectively5.
We report here the preparation and the spectroscopic
and structural study of a true pentacoordinate adduct in-
650
Sousa et al.
volving diphenyltin (IV) dichloride and the disulphoxide
2-phenyl-1,3-dithiane trans-1,
trans-3-dioxide,
[CH2(CH2)2SOCH(Ph)SO].
Of the two SO functional groups only one formed a
bond with the Sn atom, and no appreciable intermolecular
interaction was observed between individual adduct molecules.
Experimental
The ligand was kindly provided by Prof. C. Celso, who
had previously synthesised it.
Equal amounts (1.45 m mole) of both Ph2SnCl2 and the
ligand were dissolved in 10 mL of dry EtOH. After refluxing for 2 h, the mixture was filtered, and a clear solution
obtained. Slow cooling and evaporation of this solution
yielded an abundant crop of needle-like colourless crystals.
These were filtered off and washed with ether. The yield of
pure product was 0.60 g (72%), and the adduct decomposed
at 177 °C. An attempt to prepare a 2:1 adduct using a large
excess of ligand was unsuccessful. C, H analysis of the
product gave C, 46.02; H, 3.82%; calculated for
C22H22O2S2Cl2Sn gives C, 46.18; H, 3.85%.
I. R. spectra were recorded from a 283 B Perkin-Elmer
instrument using CsI pellets. Mössbauer spectra were obtained from a constant acceleration spectrometer moving a
CaSnO3 source at room temperature. Samples were analysed at 85 K with respect to that source. 119Sn NMR spectra
were run in CDCl3 in a 250 MHz Bruker instrument, using
Me4Sn as a reference. The molecular structure of the adduct
was established by a single crystal diffraction study using
an Enraf-Nonius CAD-4 diffractometer.
Crystal data for C22H22O2S2Cl2Sn: M = 572.1, monoclinic space group P21/c, cell dimensions, a = 15.126 (1), b
= 9.603 (1), c = 16.270 (3) Å; β = 101.82 (1)º, V = 2313.1
Å3, Z = 4, Dcalc = 1.64 g cm-3. Monochromated Mo Kα
radiation λ = 0.71069 Å, µ = 15.3 cm-1. The structure of the
crystal (0.1 x 0.1 x 0.05 mm) was solved by routine heavy
atom techniques and refined by full-matrix least-squares
methods with non-H atoms anisotropic, using EnrafNonius SDP programs. 2949 significant reflections with
|F2 | > 2σ (F2) were used in the refinement, which converged at R = 0.039 and R’= 0.049.
J. Braz. Chem. Soc.
Results and Discussion
Table 1 presents spectroscopic data for our adduct as
well as for its precursors. The I.R. spectrum of the ligand
shows only one SO band at 1044 cm-1, which in the adduct
appears at 1044 and 950 cm-1, indicating two different SO
groups. This is consistent with the fact that one SO function
is bonded to the metal, causing the shift to lower frequency
(950 cm-1), whereas the other SO group remains uncomplexed, which accounts for its practically unchanged frequency. The I.R. spectrum also shows a band at 420 cm-1,
which we assigned to the SnO vibration6. The SnCl bands
were shifted to lower frequencies compared to the precursor Ph2SnCl2, which is characteristic of adducts of organotin halides6.
The 119Sn NMR spectrum in CDCl3 showed a single
absorption at δ -62, upfield from Ph2SnCl2, due to enhanced
shielding of the Sn nucleus in the adduct7, compared to the
precursor (δ -33).
The 119Sn Mössbauer spectrum of the adduct showed
an increase in the quadrupole splitting and no variation in
the isomer shift, compared to Ph2SnCl2. The increase in the
quadrupole splitting may be accounted for by a greater
asymmetry in the electronic density distribution around the
Sn nucleus, whereas the invariance in δ is surprising. An
expansion in the coordination number of tin upon adduct
formation usually tends to produce lower δ values as a
consequence of rehybridisation and less s orbital participation in the overall hybrid orbitals8. Of course δ values do
not depend only on the hybridisation of tin, but also on the
total charge distribution, i.e., on the polarisation of the
bonds. The two effects may have acted here to balance each
other out, leading to the same value of δ in both the
precursor and the adduct.
Figure 1 shows the molecular structure of the adduct
and Fig. 2 the corresponding unit cell. Table 2 presents the
most important bond distances and angles, as well as some
of the dihedral angles of the adduct.
Figure 1 shows the adduct as a pentacoordinate trigonal
bipyramidal species, and Fig. 2 shows the arrangement of
the individual molecules in their unit cell. The monomeric
character of the adduct is shown by the fact that the SnCl’(1) distance, between the Sn atom of a given molecule
Table 1. Spectroscopic Data.
I.R. absorptions (cm-1)
Compound
νSO
Ligand
a
Ref. 9.
Sn n.m.r. (δ)
νSnO
119
Sn Mössbauer (mms-1)
δ
∆
1044
364, 356a
Ph2SnCl2
adduct
νSnCl
119
1040, 950
295, 240
420
-33
1.32
2.85
-62
1.32
3.22
Vol. 8, No. 6, 1997
Adduct Formation Between Diphenyltin Dichloride and 2-phenyl-1,3-dithiane trans-1-trans-3-dioxide
651
Figure 1. The molecular structure of the adduct [Ph 2SnCl2.CH2(CH2)2 SO(Ph)SO]
and the axial Cl’ atom of its nearest neighbour was found
to be 4.29 Å, greater than the sum of the van der Waals radii
of Sn (2.20 Å) and Cl (1.70-1.90 Å)10. Figure 2 clearly
shows that the self-association so common in organotin
compounds is not present in this case, and the complex is
indeed pentacoordinate.
The trigonal bipyramidal stucture of the monomer
shows two nearly identical equatorial Sn-C bonds and a
longer Sn-Cl (2) bond, as expected. The equatorial angles
are 108.8 (2)º and 110.2 (1)º for Cl (2)-Sn-C (11) and Cl
(2)-Sn-C (17), respectively, whereas the C (11)-Sn-C (17)
angle is 138.6 (2)º. The axial angle Cl (1)-Sn-O (1) is 173.1
(1)º, showing a small deviation from a regular trigonal
bipyramidal angle of 180º. The Sn-O (1) distance is 2.367
(3) Å, and the two S-O distances are significantly different:
S(1)-O (1) is 1.533 (4) Å, whereas S (2)-O (2) is 1.450 (6)
Å, as a consequence of the former being complexed to Sn,
and the latter remaining nonbonded.
It is interesting to compare our results with literature
data for the similar pentacoordinate adduct
[Me2SnCl2.O=S(CH2Ph)2]4. In the latter complex the two
equatorial Cl-Sn-C angles are 108.2 (6) and 113.0 (6)º,
respectively, and the equatorial C-Sn-C angle is 136.4
(19)º. The axial Cl-Sn-O angle is 173.9 (4)º, and the Sn-O
and S-O distances are 2.319 (10) and 1.488 (21) Å, respectively.
The two equatorial phenyl groups in our complex are
almost perpendicular to each other; indeed their dihedral
angle is 87.35º. The equatorial phenyl group represented by
atoms C (17) to C (22) and the phenyl group of the ligand
[C (5) to C (10)] form a dihedral angle of 84.04º. In contrast,
the phenyl group of the ligand and the second equatorial
phenyl ring [C (11) to C (16)] are almost parallel, with a
dihedral angle of only 7.00º between them.
Additional crystallographic data can be obtained from
the authors on request.
652
Sousa et al.
J. Braz. Chem. Soc.
Table 2. X-Ray Diffraction Data for the Adduct [Ph 2SnCl2.CH2(CH2)2SOCH(Ph)SO].
Intermolecular distances (Å)
Bond Angles (º)
Dihedral Angles (º)
Sn - Cl (1)
2.455 (1)
Cl (1) - Sn - Cl (2)
90.35 (6)
Planes 1-2
87.35 ± 0.18
Sn - Cl (2)
2.374 (2)
Cl (1) - Sn - C (11)
97.2 (1)
Planes 1-3
7.00 ± 1.44
Sn - O (1)
2.367 (3)
Cl (1) - Sn - O (1)
173.1 (1)
Planes 2-3
84.04 ± 0.18
Sn - C (11)
2.118 (5)
Cl (2) - Sn - O (1)
82.8 (1)
Sn - C (17)
2.122 (5)
Sn - O (1) - S (1)
128.5 (2)
S (1) - O (1) 1.533 (4)
Cl (1) - Sn - C (17)
96.0 (1)
S (2) - O (2) 1.450 (6)
Cl (2) - Sn - C (11)
108.8 (2)
Cl (2) - Sn - C (17)
110.2 (1)
O (1) - Sn - C (11)
84.3 (2)
O (1) - Sn - C (17)
87.2 (2)
C (11) - Sn - C (17)
138.6 (2)
O (11) - S (1) - C (1)
105.0 (3)
O (1) - S (1) - C (4)
99.1 (3)
O (2) - S (2) - C (3)
108.4 (3)
O (2) - S (2) - C (4)
107.9 (3)
a Plane 1: C (11) C (12 ) C (13) C (14) C (15) C (16). Plane 2: C (17) C (18) C (19) C (20) C (21) C (22). Plane 3: C (5) C (6) C (7) C (8) C(9) C (10).
References
Figure 2. The unit cell of the adduct [Ph2SnCl2.CH2(CH2)2SOCH
(Ph)SO]
Acknowledgments
The authors are grateful to Prof. C. Celso for providing
a sample of the ligand used in this work, and to Prof. A.
Abras for the Mössbauer spectra. CNPq and Fapemig are
thanked for financial support.
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