Synthesis, spectroscopic studies and crystal structures of [Et 2Sn(O2AsMe2)2] and [Ph 2Sn(O2AsMe2)(μ-OMe)]2

Article abstract of DOI:10.1002/zaac.201100098

[Et₂Sn(O₂AsMe₂)₂] (1) and [Ph₂Sn(O₂AsMe₂)(μ-OMe)]₂ (2) were synthesized by treatment of Et₂SnO and Ph₂SnS with HO₂AsMe₂ in Methanol, respectively. The compounds were characterized by elemental analyses, vibrational spectroscopy and mass spectrometry. According to X-ray diffraction measurements compound 1 crystallizes monoclinic in space group P2₁/n with cell parameters a = 804.89(3), b = 987.11(5), c = 966.42(4) pm, β = 113.354(3)°. The unit cell parameters of 2, which crystallizes in the same space group, are a = 974.4(1), b = 1463.3(1), c = 1228.9(1) pm, β = 111.324(3)°. The (SnOAsO)₄ rings of 1 are linked and form a two-dimensional network with the SnEt groups pointing into the holes of the next layer. Compound 2 occurs as a dimer with internal Sn(OMe)₂Sn bridges in the (SnOAsO)₂ rings. The vibrational and mass spectra are given and discussed. Copyright

Full text of DOI:10.1002/zaac.201100098

ARTICLE
DOI: 10.1002/zaac.201100098
Synthesis, Spectroscopic Studies and Crystal Structures of
[Et2Sn(O2AsMe2)2] and [Ph2Sn(O2AsMe2)(μ-OMe)]2
Abdel-Fattah Shihada[a] and Frank Weller*[b]
Keywords: Organotin Dimethylarsinates; Crystal structure; Vibrational spectroscopy; Mass spectrometry; Methoxo bridges
Abstract. [Et2Sn(O2AsMe2)2] (1) and [Ph2Sn(O2AsMe2)(μ-OMe)]2 (2) eters of 2, which crystallizes in the same space group, are a = 974.4(1),
were synthesized by treatment of Et2SnO and Ph2SnS with HO2AsMe2 b = 1463.3(1), c = 1228.9(1) pm, β = 111.324(3)°. The (SnOAsO)4
in Methanol, respectively. The compounds were characterized by ele- rings of 1 are linked and form a two-dimensional network with the
mental analyses, vibrational spectroscopy and mass spectrometry. Ac- SnEt groups pointing into the holes of the next layer. Compound 2
cording to X-ray diffraction measurements compound 1 crystallizes occurs as a dimer with internal Sn(OMe)2Sn bridges in the (SnOAsO)2
monoclinic in space group P21/n with cell parameters a = 804.89(3), rings. The vibrational and mass spectra are given and discussed.
b = 987.11(5), c = 966.42(4) pm, β = 113.354(3)°. The unit cell param-
1 Introduction
2 Results and Discussion
The reactions of diorganotin dichlorides R2SnCl2 with
HO2AsMe2 in methanol at ambient temperature produce
[R2ClSn(O2AsMe2)] (R2 = Me2, Et2,[1] Bu2[2]). Meanwhile
[Ph3Sn(O2AsMe2)] and the dimer [PhClSn(O2AsMe2)(μ-
OMe)]2 were formed by the reaction of NaO2AsMe2 with
The reaction of Et2SnO with HO2AsMe2 in a 1:2 molar ratio
in refluxing methanol leads to the formation of
[Et2Sn(O2AsMe2)2] (1). Treatment of Ph2SnS with HO2AsMe2
in
methanol
at
ambient
temperature
afforded
[Ph2Sn(O2AsMe2)(μ-OMe)]2 (2) according to the following
equation.
Ph3SnCl
and
Ph2SnCl2
respectively.[2]
Crystalline
[Bu2Sn(O2AsMe2)2] was synthesized by the reaction of
Bu2SnO and HO2AsMe2.[3] X-ray diffraction studies of
[R2ClSn(O2AsMe2)] and [Ph3Sn(O2AsMe2)] show that the
O2AsMe2 groups behave as bidentate bridging ligands between
2Ph2SnS + 2HO2AsMe2 + 2HOMe
→ [Ph2Sn(O2AsMe2)(μ-OMe)]2 + 2H2S
The reactions of Ph2SnCl2 with NaO2AsMe2 and with
HO2PPh2 in methanol produce also dimers containing
the tin atoms, thus forming polymeric chain structures.[1,2]
A
MeO
groups
[PhClSn(O2AsMe2)(μ-OMe)]2
and
two-dimensional polymeric structure with (SnOAsO)4 sixteen-
membered rings was reported for [Bu2Sn(O2AsMe2)2].[3]
An analogous polymeric structure with (SnOPO)4 rings
was found in [Et2Sn(O2PMe2)2].[4] In addition, the
tetramers [Me3Sn(O2PPh2)]4,[5] [Me3Pb(O2PPh2)]4,[6] and
[Bu3Sn(O2Pcyc)]4 (cyc = 1,1,2,3,3-pentamethyltrimethylene)[7]
show also sixteen-membered ring structures with bridging
phosphinato ligands between the metal atoms. Continuing our
work on the preparation and structural studies of organotin
dimethylarsinates, we describe here the synthesis and crystal
structures of [Et2Sn(O2AsMe2)2] (1) and [Ph2Sn(O2AsMe2)(μ-
OMe)]2 (2). The vibrational and mass spectra are given and
discussed.
[PhClSn(O2PMe2)(μ-OMe)]2, which indicate that methanol be-
haves as solvent and reactant. X-ray diffraction studies show
[2]
that 2 and [PhClSn(O2AsMe2)(μ-OMe)]2 are centrosymmet-
ric dimers involving hexacoordinate tin atoms connected by
two bridges of O2AsMe2 and two bridges of OMe groups
forming Sn2O4As2 eight-membered and Sn2O2 four-membered
rings. A similar structure has been found for the analogous
phosphorus-containing dimer [PhClSn(O2PMe2)(μ-OMe)]2.[8]
Furthermore, [Ph2Sb(μ-O)(O2AsMe2)]2, which was prepared
by treatment of (Ph2SbBrO)2 with NaO2AsMe2 in CH2Cl2
shows a similar quadruply bridged structure with Sb2O4As2
eight-membered and Sb2O2 four-membered rings.[9] It is worth
noting, that [(Me2SnOSAsMe2)2O]2 was obtained by the reac-
tion of Me2SnS with HO2AsMe2 in methanol at ambient
temperature.[3]
* Dr. F. Weller
E-Mail: wellerf@mailer.uni-marburg.de
[a] Department of Chemistry
Faculty of Science
Vibrational Spectroscopy
Hashemite University
P.O.Box: 150459
Selected IR and Raman frequencies (Table 1) are assigned
by comparison with the vibrational spectra of related organotin
dimethylarsinates.[1–3] In agreement with bridging bidentate
O2AsMe2 groups, the vibrational spectra of 1 and 2 exhibit
Zarqa, 13115 Jordan
[b] Fachbereich Chemie
Philipps-Universität Marburg
Hans Meerwein-Str.
35032 Marburg, Germany
1378
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 637, 1378–1382

[Et2Sn(O2AsMe2)2] and [Ph2Sn(O2AsMe2)(μ-OMe)]2
ν(AsO2) vibrations in the range between 790–900 cm–1. The Mass Spectrometry
frequencies due to νas(AsC2) and νs(AsC2) appear in the region
between 580–650 cm–1.[10]
Table 2 gives the characteristic ions in the EI mass spectra
(70 eV) of compounds 1 and 2. The mass spectrum of 1 shows
the [M – Et]+ ion (m/e = 423) in considerable abundance
whereas the [M – Ph]+ ion (m/e = 805) appears in the mass
spectrum of 2 with low abundance. However the ion
Ph3Sn2(O2AsMe2)2O+ (2 minus Me2O and Ph-group, m/e =
759) appears in high abundance. In agreement with the poly-
meric nature of 1, the mass spectrum exhibits ions with masses
greater than the molecular mass of the monomer. The peaks at
527 and 511 in the mass spectrum of 1 are assigned to
Table 1. Selected IR and Raman frequencies /cm–1 of 1 and 2.
[Et2Sn(O2AsMe2)2] [Ph2Sn(O2AsMe2)(μ-OMe)]2 Assignment
(1)
(2)
IR
Raman
IR
Raman
999 vs
1018 s
ν(O-CH3)
Ph ring breath-
ing
897 vs 888 vw
855 vs
900 w
ν(AsO2)
+
+
EtHSn2O4As2Me3 and EtHSn2O3As2Me3 respectively. These
ions may be formed by β-hydrogen elimination. The ion
ν(AsO2)
852 vs
851 w
817 vw
646 m
620 w
ν(AsO2)
+
Et2Sn2O4As2Me3 (m/e = 555) which appears in the spectrum
819 vs 821 m-s
638 s 637 m
837 vs
648 m
620 vw
ν(AsO2)
νas(AsC2)
(C-C-C) Ph
bend
of
1
has also been observed in the spectrum of
[Et2ClSn(O2AsMe2)].[1] The spectra of 1 and 2 display the
tin(II)-containing ion Sn(O2AsMe2)+, which seems to be a
characteristic feature in the mass spectra of organotin
dimethylarsinates.[1–3] The mass spectrum of 2 shows the ions
Ph3Sn+, Ph2Sn+, PhSn+ in relatively high abundance. The ap-
pearance of Ph3Sn+ indicates a phenyl group transfer.
605 m 607 s-vs
525 m
611 m-s
470 vw
445 m
νs(AsC2)
νas(SnC2)
ν(Sn-O-Sn)
νs(SnC2)
ν(Sn-OAs)
ν(Sn-OAs)
νas(SnPh2)
νs(SnPh2)
494 m
450 vs
472 s-vs
429 m
417 s 418 m
258 w
215 m
Structural Results
A
comparison
of
the
vibrational
spectra
of
Sixteen-membered rings (SnOAsO)4 occur as part of
[Et2Sn(O2AsMe2)2] (1) and the structural analogue layered two-dimensional networks in
1 (Figure 1) and
[Bu2Sn(O2AsMe2)2][3] shows that decreasing the size of the [Bu2Sn(O2AsMe2)2].[3] Other examples of this structural ar-
alkyl groups has little effect on the frequencies of the O2AsMe2 rangement are reported with phosphinate[4] and fluorosulfate
ligands.
bridging ligands.[11] Some characteristic properties of these
The vibrational spectra of 1 show νas(SnC2) at 525 cm–1 (IR) layer compounds are listed in Table 3. The interlayer distance
and νs(SnC2) at 472 cm–1 (Raman), which is in agreement with is shown to depend mainly on the organic tin substituent, and
a linear C–Sn–C arrangement. The bands at 494 cm–1 (IR) and the mesh size to vary with the nature of the bridging ligand
470 cm–1 (Raman) in the vibrational spectra of 2 are assigned and layer folding. The planarity of the sheets as expressed in
to ν(Sn–O–Sn) vibrations. At 999 cm–1, the Raman spectrum the deviation of the bridging atoms from the tin atom plane, is
of 2 exhibits the characteristic and very strong band due to found equally high for the phosphinate and the arsinates. Se-
phenyl ring breathing.
vere folding in the fluorosulfate ligand is the reason for a small
Table 2. Characteristic ions formed in the 70 eV mass spectra of 1 and 2 (m/e /%).
[Et2Sn(O2AsMe2)2] (1)
[Ph2Sn(O2AsMe2)(μ-OMe)]2 (2)
+
Ph3Sn2(O2AsMe2)2(OMe)2
805 (2)
759 (90)
605 (7)
Ph3Sn2(O2AsMe2)2O+
PhSn2(O2AsMe2)2O+
+
Et2Sn2O4As2Me3
EtHSn2O4As2Me3
EtHSn2O3As2Me3
555 (70)
527 (18)
511 (13)
449 (33)
423 (14)
+
+
+
Et3SnO2As2Me4
+
EtSn(O2AsMe2)2
Ph2Sn(O2AsMe2)
+
411 (9)
+
EtSnO2As2Me4
391 (92)
Ph3Sn+
351 (77)
305 (18)
274 (66)
257 (5)
197 (65)
107 (100)
91 (46)
Ph2SnOMe+
Ph2Sn+
+
Sn(O2AsMe2)
257 (50)
PhSn+
+
AsO2
107 (92)
91 (100)
AsO+
Z. Anorg. Allg. Chem. 2011, 1378–1382
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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A.-F. Shihada, F. Weller
ARTICLE
Table 3. Some characteristic properties of similar layer structures (rounded values).
Space group interlayer distance /pm max. ring atom dev. of tin atom plane /pm
P21/n 737 16
P21/n 727
Pbca (HT) 983
P21/c 695
mesh size r(Sn–Sn)diag /pm
[Et2Sn(O2PMe2)2][4]
[Et2Sn(O2AsMe2)2] (1)
[Bu2Sn(O2AsMe2)2][3]
[Me2Sn(O2SOF)2][11]
985/974
982/987
1003/975
814/834
a)
22
43
153
a) Measured at 193 K. All other data taken from RT measurements.
Table 4. Selected bond lengths /pm and angles /° for
[Et2Sn(O2AsMe2)2] (1).
mesh opening, and the low volumes of methyl group and
bridging ligand are responsible for the shorter distance be-
tween the sheets.
Sn–C(1)
215.2(2)
O(1)–Sn–O(2)' 87.87(5)
Sn-O1, Sn–O(2)''
218.2(1),218.5(1) O(1)–As–O(2) 107.42(7)
As–O(1), As–O(2) 168.3(1),168.3(1) O(1)–As–C(3) 110.76(8)
As–C(3), As–C(4) 190.6(2), 190.9(2) O(1)–As–C(4) 108.61(8)
O(2)–As–C(3) 111.10(8)
As–O(1)–Sn
129.71(8)
131.70(7)
O(2)–As–C(4) 111.89(8)
C(3)–As–C(4) 107.07(9)
As–O(2)–Sn'''
Symmetry transformations used to generate equivalent atoms:
El' : –x, –y + 1, –z + 1;
El'': x – 1/2, –y + 1/2, z – 1/2;
El''' : –x + 1/2, y – 1/2, –z + 3/2
accordance with the greater Sn–Sn distance in 2 (347.97(2) pm
as compared to 340.84(2) pm in the phenyl-chloro-substituted
compound) and is due to the steric needs of the two phenyl
groups. The two SnO2 units within the eight-membered rings
of the dimer are very neatly coplanar (max. deviation of the
best plane 0.44 pm), and the arsenic atom is placed 44 pm
from this plane. The configuration at the triply coordinated
atom O(3) is pyramidal with an angular sum of 348°.
Figure 1. Perspective view[17] of a (SnOAsO)4 mesh in the polymeric
network 1 with the atomic numbering scheme. Thermal ellipsoids are
shown at 50 % probability level.
Bond lengths and angles of compound 1 are summarized in
Table 4. Octahedral configuration at the tin atom (max. devia-
tion of 2.13° from 90°) and tetrahedral surrounding of the ar-
senic atom (max. dev. 2.39° from tetrahedral angle) are ap-
proximately realized. By comparing compound 1 with its
isostructural phosphorus analogue,[4] it is obvious that the an-
gles O–P–O and O–P–Sn in the ring are significantly wider
than the corresponding angles in 1. This is not only a sign of
steric stress, but also hints enhanced multiple bond character
in the short P–O bonds giving also rise to an increase in the
Sn–O bond length (222.4(1)/221.8(1) pm vs. 218.5(1)/218.2(1)
pm in the arsinate).
Figure 2. ORTEP[17] view of a dimeric molecule of 2 with displace-
Compound 2 forms a centrosymmetric dimer consisting of
(Sn–O–As–O)2 eight-membered rings, in which the tin atoms
are linked by two MeO⎯ bridges (Figure 2). An analogue con-
ment ellipsoids at 50 % probability level.
figuration has been found for an arsinate[2] and
a
phosphinate,[8] in which the tin atoms are asymmetrically sub-
stituted by a chloride and a phenyl group causing the bridge
to be strongly asymmetric on account of the different trans-
positioned ligands. Bond lengths and bond angles (Table 5)
correspond well with the values found in the above arsenate,[2]
except for the angles O–As–O and Sn–O–Sn in the almost
3 Experimental Section
The chemical reagents employed were obtained from commercial sour-
ces and were used without further purification. Sodium sulfide
(Na2S·xH2O, 60–62 %) was provided from Riedel-de Haën.
Ph2SnS was prepared according to literature by treating Ph2SnCl2 with
symmetrical MeO⎯ bridge, which are by 3° wider. This is in Na2S.[12] Infrared spectra were measured using KBr pellets with a
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Z. Anorg. Allg. Chem. 2011, 1378–1382

[Et2Sn(O2AsMe2)2] and [Ph2Sn(O2AsMe2)(μ-OMe)]2
Table 5. Selected bond lengths /pm and angles /° for
[Ph2SnO2AsMe2(μ-OMe)]2 (2).
X-ray Structural Investigations: The crystals of 1 and 2 were han-
dled in oil, mounted on 0.2 mm cryoloops and measured at 193 K with
a Stoe diffractometer IPDS I. After data reduction[13] both data sets
were subjected to numerical absorption corrections. The structures
were solved by direct methods and the models were refined by full-
matrix least-squares methods.[14,15] Hydrogen positions were kept rid-
ing on calculated values. Crystal Data, experimental details, and details
about structure solution and refinement may be taken from Table 6.
The geometric calculations were made with PLATON.[16]
Sn–O(1)/Sn–O(2)'
Sn–O(3)/Sn–O(3)'
As–O(1)/As–O(2)
As–C(3)/As–C(4)
212.2(2)/211.3(2) C(11)–Sn–C(21) 101.45(6)
214.8(1)/215.7(1) O(1)–Sn–O(2)' 163.00(6)
168.6(2)/167.8(2) O(3)–Sn–O(3)' 72.15(6)
190.0(2)/190.9(2) Sn–O(3)–Sn'
107.85(6)
116.08(7)
109.5(1)
Sn–C(11)/Sn–C(21) 218.2(2)/218.5(2) O(2)–As–O(1)
C(3)–As–C(4)
As–O(1)–Sn
As–O(2)–Sn'
124.99(8)
126.09(8)
Symmetry transformation used to generate equivalent atoms:
Crystallographic data (excluding structure factors) have been deposited
with the Cambridge Crystallographic Data Centre as supplementary
publication nrs. CCDC-872551 (1) and -872550 (2). Details are availa-
ble, free of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033; E-Mail
deposit@ccdc.cam.ac.uk).
El' : –x + 1, –y, –z + 1
Bruker Instrument IFS 88. The Raman spectra were obtained using a
Jobin Yvon Labram HR 800 instrument with 632.8 nm helium neon
laser excitation. Mass spectra were recorded with a Finnigan MAT S
(EI 70eV). The chemical analyses were carried out in the analytical
laboratory of Fachbereich Chemie der Universität Marburg.
References
[1] A.-F. Shihada, F. Weller, Z. Anorg. Allg. Chem. 2002, 628, 1007.
[2] A.-F. Shihada, F. Weller, Z. Anorg. Allg. Chem. 2008, 634, 339.
[3] A.-F. Shihada, M. Alaqarbeh, F. Weller, W. Massa, Z. Anorg. Allg.
Chem. 2009, 635, 1384.
Synthesis of [Et2Sn(O2AsMe2)2] (1): Et2SnO (0.39 g, 2 mmol) and
HO2AsMe2 (0.55 g, 4 mmol) were mixed in methanol (50 mL). The
reaction mixture was heated under reflux for 4h, filtered off and the
mother liquor was set aside at ambient temperature in an open flask.
After few days the formed precipitate was filtered off and recrystal-
lized from methanol. The yield was 0.54 g.
[4] A.-F. Shihada, F. Weller, Z. Naturforsch. 1997, 52b, 587.
[5] M. G. Newton, I. Haiduc, R. B. King, C. Silvestru, J. Chem. Soc.,
Chem. Commun. 1993, 1229.
[6] R. A. Varga, J. E. Drake, C. Silvestru, J. Organomet. Chem. 2003,
675, 48.
C8H22As2O4Sn (450.8): Calcd. C 21.31, H 4.92; found C 21.29, H 4.91
[7] V. Chandrasekhar, V. Baskar, A. Steiner, S. Zacchini, Organome-
tallics 2004, 23, 1390.
Synthesis of [Ph2Sn(O2AsMe2)(μ-OMe)]2 (2):
A solution of
HO2AsMe2 (0.29 g, 2.1 mmol) in methanol (25 mL) was added to a
solution of Ph2SnS (0.30 g, 1.0 mmol) in 2:1 methanol/ethanol
(150 mL). The mixture was set aside at ambient temperature in a
closed flask. After 2d a small amount (yield 110 mg) of shiny crystals
of 2 had formed and was filtered off.
[8] A.-F. Shihada, F. Weller, Z. Anorg. Allg. Chem. 2006, 632, 2238.
[9] M. N. Gibbons, D. B. Sowerby, J. Chem. Soc., Dalton Trans.
1997, 2785.
[10] R. A. Zingaro, K. J. Irgolic, D. H. O’Brien, L. J. Edmonson Jr.,
J. Am. Chem. Soc. 1971, 93, 5677.
Table 6. Crystallographic and measurement data for the structures of 1 and 2.
1
2
Formula, M
[Et2Sn(O2AsMe2)2], 450.79
[Ph2SnO2AsMe2(μ-OMe)]2, 881.82
0.15 × 0.12 × 0.09
P21/n Z = 2
Crystal size/mm
Space group
0.27 × 0.13 × 0.11
P21/n, Z = 2
804.89(3)
a /pm
974.4(1)
b /pm
987.11(5)
1463.3(1)
c /pm
966.42(4)
1228.9(1)
β /°
113.354(3)
111.324(3)
Cell volume /m3
Density /Mg·m–3
Absorption coefficient μ /mm–1
Absorption corr. Type, Tmin/Tmax
Diffractometer type
Radiation
704.93(5) × 10–30
2.124
1632.2(1) × 10–30
1.794
6.465
3.581
numerical, 0.3575/0.6134
numerical, 0.5993/0.7787
IPDS I (Stoe)
Mo-Kα, graphite monochromator
Measuring range hkl
–10 ≤ h ≤ 11
–13 ≤ k ≤ 13
–13 ≤ l ≤ 12
29.14°
–12 ≤ h ≤ 12
–18 ≤ k ≤ 18
–15 ≤ l ≤ 15
26.76°
12438
3461/3071 >2σ(I)
166
Measuring range, max. Ө
Reflections (total)
10218
Reflections unique/observed
Refined parameters
1900/1780 >2σ(I)
86
Programs used
SHELXS-97, SHELXL-97,[15] SHELXTL,[17] WINGX[14]
0.0015(2)
Extinction coeff. (SHELXL)
wR2(F2)/R(observed F)
Goodness of Fit S
0.0509/0.0201
1.061
0.736/–0.717
0.0480/0.0191
1.020
0.602/–0.438
final diff. electron density max./ min. /e·Å–3
Z. Anorg. Allg. Chem. 2011, 1378–1382
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1381

A.-F. Shihada, F. Weller
ARTICLE
[11] F. H. Allen, J. A. Lerbscher, J. Trotter, J. Chem. Soc. A 1971, [16] A. L. Spek, PLATON-89, University of Utrecht, 1989.
2507.
[17] G. M. Sheldrick, SHELXTL, Release 5.03 for Siemens Analytical
X-ray Instruments Inc., Madison, WI, 1990.
[12] H. Berwe, A. Haas, Chem. Ber. 1987, 120, 1175.
[13] K. Harms, XCAD4, Program for Data Reduction, Marburg, 1993.
[14] L. J. Farrugia, WINGX, Crystallographic Programs for Windows,
J. Appl. Crystallogr. 1999, 32, 837.
Received: March 1, 2011
Published Online: June 7, 2011
[15] G. M. Sheldrick, SHELXS-97, SHELXL-97 Programs for the So-
lution and Refinement of Crystal Structures, Göttingen, 1997.
1382
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© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 1378–1382