Organotin(IV) complexes of 2-[(2′,4′,6′- trichlorophenylamido)]benzoic acid: Synthesis, coordination chemistry, and semi-empirical study

Article abstract of DOI:10.1080/10426500903486722

A new series of organotin(IV) complexes of aniline derivatives, R ₂SnL₂ and R₃SnL [where R = Me, n-Bu, n-Oct, and Ph], have been synthesized by the reaction of ligand acid with respective organotin halides in the presence of triethylamine as base or dioctyltin oxide using a Dean-Stark trap for the removal of water under reflux conditions. Experimental details for the preparation and characterization, including elemental analysis, IR, semi-empirical study, multinuclear NMR (1H, 13C, and 119Sn spectra and EI mass spectral studies) of all reported complexes are provided. The IR data indicate that in both di- and triorganotin(IV) carboxylates, the ligand moiety -COO acts as a bidentate group in the solid state. Multinuclear NMR data show that triorganotin complexes exhibits a four-coordinated geometry, while diorganotin(IV) complexes show a coordination number greater than four, probably five or six, in solution state. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/10426500903486722

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Organotin(IV) Complexes of 2-[(2′,4′,6′-
Trichlorophenylamido)]benzoic Acid:
Synthesis, Coordination Chemistry, and
Semi-Empirical Study
Saira Shahzadi a , Saqib Ali b , Khadija Shahid b , Saroj K. Sharma c &
Kushal Qanungo c
a Department of Chemistry , GC University , Faisalabad, Pakistan
b Department of Chemistry , Quaid-i-Azam University , Islamabad,
Pakistan
c Deptartment of Applied Sciences and Humanities, Faculty of
Engineering and Technology , Mody Institute of Technology and
Science (Deemed University) , Lakshmangargh, India
Published online: 24 Sep 2010.
To cite this article: Saira Shahzadi , Saqib Ali , Khadija Shahid , Saroj K. Sharma & Kushal Qanungo
(2010) Organotin(IV) Complexes of 2-[(2′,4′,6′- Trichlorophenylamido)]benzoic Acid: Synthesis,
Coordination Chemistry, and Semi-Empirical Study, Phosphorus, Sulfur, and Silicon and the Related
Elements, 185:10, 2045-2053, DOI: 10.1080/10426500903486722
To link to this article: http://dx.doi.org/10.1080/10426500903486722
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Phosphorus, Sulfur, and Silicon, 185:2045–2053, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500903486722
ORGANOTIN(IV) COMPLEXES OF 2-[(2ꢀ,4ꢀ,6ꢀ-
TRICHLOROPHENYLAMIDO)]BENZOIC ACID:
SYNTHESIS, COORDINATION CHEMISTRY,
AND SEMI-EMPIRICAL STUDY
Saira Shahzadi,1 Saqib Ali,2 Khadija Shahid,2
Saroj K. Sharma,3 and Kushal Qanungo3
1Department of Chemistry, GC University, Faisalabad, Pakistan
2Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan
3Deptartment of Applied Sciences and Humanities, Faculty of Engineering and
Technology, Mody Institute of Technology and Science (Deemed University),
Lakshmangargh, India
A new series of organotin(IV) complexes of aniline derivatives, R2SnL2 and R3SnL [where
R = Me, n-Bu, n-Oct, and Ph], have been synthesized by the reaction of ligand acid with
respective organotin halides in the presence of triethylamine as base or dioctyltin oxide using
a Dean–Stark trap for the removal of water under reflux conditions. Experimental details
for the preparation and characterization, including elemental analysis, IR, semi-empirical
study, multinuclear NMR (1H, 13C, and 119Sn spectra and EI mass spectral studies) of all
reported complexes are provided. The IR data indicate that in both di- and triorganotin(IV)
carboxylates, the ligand moiety COO acts as a bidentate group in the solid state. Multin-
uclear NMR data show that triorganotin complexes exhibits a four-coordinated geometry,
while diorganotin(IV) complexes show a coordination number greater than four, probably
five or six, in solution state.
Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental
file.
Keywords Organotin(IV) carboxylates; semi-empirical study; spectroscopic studies
INTRODUCTION
Organotin compounds show a diversity of applications. They are used as fungicides
and bactericides. In addition, diorganotin compounds exhibit greater antitumor activity than
the corresponding triorganotin compounds.1 Organotin compounds are also interesting
in view of the considerable structural diversity they possess; this aspect has attracted
Received 24 July 2009; accepted 13 November 2009.
S.A. is thankful to Quaid-i-Azam University, Islamabad, for financial support. S.K.S. and K.Q. thank the
Head, App Sci. and Dean FET, MITS, for encouragement and support.
Address correspondence to Saira Shahzadi, Department of Chemistry, GC University, 38000-Faisalabad,
Pakistan. E-mail: sairashahzadi@yahoo.com and Saqib Ali, Department of Chemistry, Quaid-i-Azam University,
45320-Islamabad, Pakistan. E-mail: drsa54@yahoo.com
2045

2046
S. SHAHZADI ET AL.
Cl
O
O
C
Cl
NH
C
OH
Cl
Figure 1 Structure of 2-[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid (HL).
the attention of a number of researchers and, in recent years, a multitude of structural
types have been discovered.2 The increasing importance of organotin(IV) compounds are
not only because of extensive commercial use3 in industry as PVC stabilizing agents
and anti-neoplastic agents, in agriculture as wood preservatives,4 and as fungicide and
pesticide, but also due to the environmental consequences of the widespread use of these
complexes.3 The organotin(IV) compounds are also used for pharmacological applications
such as bactericides,5 as an antitumor agent,6 as an anti-inflammatory agent,7 and as an
antitubercular.7
We have investigated the reactions of di- and triorganotin chlorides/oxide with 2-
[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid. The generic structure of the ligand frame-
work is shown in Figure 1. The characterization of the compounds is carried out by means
of 1H, 13C, 119Sn NMR, and FT-IR spectroscopy, as well as the elemental analyses, semi-
empirical study, and mass spectrometric analyses.
RESULTS AND DISCUSSION
Reactions of di- and triorganotin chlorides/oxide with a stoichiometric amount of
ligand acid were carried out at temperature of reflux in dry toulene. All the synthesized
compounds are stable and soluble in common solvents. The physical data are summarized
in Table I.
IR Spectra
The stretching frequencies of interest are those associated with COO, Sn C, and
Sn O groups and are listed in Table II. The IR spectra of the ligand and the synthesized
complexes have been recorded as KBr pellets or neat liquids in the range 4000–250 cm−1
.
The assignment of the bands is based on comparison with the spectra of the free ligand
(HL). The deprotonation of the carboxylic acid is evident from the disappearance of a broad
band, owing to the COOH group in the region 3429 cm−1 of the ligand.8 In the complexes,
the carbonyl stretching frequencies are found to be shifted to lower wave numbers, which
is ascribed to carboxylate coordination in accordance with earlier reports.9,10
The values of a difference ꢀν = νasym(COO) − νsym(COO) in the spectra of the com-
plexes are lower than the values for the ligand acid (ꢀν = 218 cm−1). These observations
suggest the anisobidentate nature of the carboxylate ligand11,12 and supports the assessment
that diorganotin(IV) carboxylates have hexa-coordinated, distorted, octahedral motifs, and
triorganotin(IV) compounds may acquire polymeric geometries containing bridging COO
groups in the solid state. This is totally consistent with the earlier reports.13,14 Diorgan-
otin(IV) carboxylates exhibit a hexa-coordinated geometry, while triorganotin(IV) show a
trigonal bipyramidal geometry. Polymeric structure is supported by trigonal bipyramidal

ORGANOTIN(IV) COMPLEXES
2047
Table I Physical data for organotin(IV) complexes of 2-[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid
Elemental analysis %
Calculated (found)
Quantity used
Compound
No.
1st
Reactant
2nd
Reactant
3rd
Reactant
Mp
(◦C)
Yield
(%)
C
H
N
(1)
(2)
(3)
(4)
(5)
HL
1.0 g
Me2SnCl2
0.31 g
Et3N
0.40 mL
78–80
105–106
158
92
90
85
75
67
43.06
(43.26) (2.48)
2.39
3.34
(3.27)
(2.90 mmol) (1.45 mmol) (2.90 mmol)
HL
1.0 g
Bu2SnCl2
0.44 g
Et3N
0.40 mL
46.95
(46.87) (3.32)
3.47
3.04
(3.17)
(2.90 mmol) (1.45 mmol) (2.90 mmol)
HL
1.0 g
Oct2SnO
0.52 g
−
51.16
(51.02) (4.55)
4.65
2.71
(2.63)
(2.90 mmol) (1.45 mmol)
HL
1.0 g
Bu3SnCl
0.78 g
Et3N
0.40 mL
172–173
146–147
49.28
(49.20) (5.25)
5.37
2.21
(2.11)
(2.90 mmol) (2.90 mmol) (2.90 mmol)
HL
1.0 g
Ph3SnCl
1.12 g
Et3N
0.40 mL
55.41
(55.32) (3.10)
3.17
2.02
(2.19)
(2.90 mmol) (2.90 mmol) (2.90 mmol)
geometry. Absorption bands in the region 480–450 cm−1 are assigned to the stretching
frequencies associated with the Sn O bonds,15 which substantiate further the formation of
tin complexes.
Mass Spectrometric Data
The mass spectral data collected at 70 eV for both the di- and triorganotin(IV) deriva-
tives are reported in Table S1 (Supplemental Materials, available online). The molecular
ion peak is observed only for the methyl derivative (1) and is consistent with the literature.16
The fragment ions containing the Sn atom are quite intense. In triorganotin(IV) car-
boxylates, the primary fragmentation is due to the loss of the R group, and the same is true
Table II Assignment of characteristic FT-IR vibrations of 2-[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid and
their organotin(IV) complexes
IR peak (cm−1
)
Compound
νOH
νNH
νC
νCOO
ꢀν
νSn
νSn
O
O
C
HL
(1)
(2)
(3)
(4)
(5)
3429b
−
3358s
3364s
3352m
3361m
3369s
3350s
1776s
1769s
1764s
1760s
1768s
1762s
1552ma
1580m
1598m
1590s
1570s
1566m
1334sb
1456m
1406s
1450s
1424m
1411m
218
124
192
140
146
155
−
−
550s
510m
570m
560w
252m
450m
461m
480w
460m
472m
−
−
−
−
aAntisymmetric
bSymmetric.
Abbreviations: s = strong; m = medium; w = weak; b = broad.

2048
S. SHAHZADI ET AL.
for diorganotin(IV) derivatives. However, the secondary and tertiary decomposition is also
followed by the loss of the R group in triorganotin(IV) derivatives, while diorganotin(IV)
derivatives manifest a slightly different pattern of fragmentation. All of the diorganotin(IV)
derivatives exhibit almost the same behavior. In these compounds, the fragmentation pro-
ceeds via two pathways. In one case, the primary fragmentation may occur through loss
of O2CRꢁ, and the secondary fragmentation involves elimination of CO2. The further frag-
mentations are due to release of the corresponding R and Rꢁ groups generating [RSn]+ and
finally [Sn]+. In the second pathway, primary fragmentation arises by loss of the R group,
and removal of CO2 provides the secondary fragmentation. Successive release of CO2,
Rꢁ, and R groups make the SnR, which ends at [Sn]+. In conclusion, the fragmentation
patterns of both di- and triorganotin(IV) carboxylates obey the established routes described
in earlier reports.16,17
NMR Spectra
Tables III and IV show the 1H, 13C, and 119Sn NMR chemical shifts of the ligand and
its complexes in CDCl3 solution. 1H NMR spectra coincide with the expected integration
1
and peak multiplicities. In H NMR spectra of all the complexes studied, the CO(OH)
resonance of the ligand is absent, which suggests the replacement of the carboxylic proton
by the organotin(IV) moiety. The –NH signal remains unchanged, which indicates that this
group is not involved in inter/intramolecular hydrogen bonding or in bonding to organotin
2
moiety. The J[119Sn 1H] coupling constant values for compound 1 is 81 Hz, which
support hexa-coordinated environment around the tin atom.15 In compound 4, a tetrahedral
geometry around tin is observed as indicated from 2J[119Sn-1H] coupling constant value15
in solution form.
In the case of diorganotin dicarboxylates, the geometry around tin in solution could
not be determined with certainty due to the fluxional behavior of the carboxylate oxygens
with coordination to tin atom; however, earlier reports suggest hexa-coordination around
tin. The alkyl carbons attached to the tin occur at the normal values in the case of methyl and
butyl tin compounds. The aromatic carbon resonances were assigned by the comparison
of experimental chemical shift with those calculated from the incremental method.18 The
Table III 1H NMR dataa of 2-[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid and its organotin complexes
Chemical shift (ppm)
Proton
HL
1
2
3
4
5
Cl3 C6H2
NH
7.63s
6.90s
7.45s
6.90s
7.50s
6.90s
7.68s
6.90s
7.36s
6.90s
7.30s
6.90s
O
C
O
C
7.50d (8.0)
7.08d (7.9)
7.78d (8.1) 7.20–7.24d,d 7.55–7.59d,d 7.27–7.31d,d
(8.2) (8.6) (8.9)
8.00–8.05d,d 8.05–8.09d,d 8.03–8.05d,d 7.68–7.72d,d 8.02–8.06d,d 8.02–8.06d,d
(8.0)
(7.9)
(8.1)
(8.2)
(8.6)
(8.9)
R
−
0.26s
[81]
0.84t [81]
1.34–1.36m
0.88–1.52m
0.98t(7.7)
1.34–1.38m
7.65–7.82m
aChemical shifts (δ) in ppm. 2J[119Sn, 1H] and nJ(1H, 1H) in Hz are listed in square brackets and parenthesis,
respectively. Multiplicity is given as: s = singlet, d = doublet, d,d = doublet of doublet, t = triplet, m = multiplet.

ORGANOTIN(IV) COMPLEXES
2049
Table IV 13C and 119Sn NMR dataa–c of 2-[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid and its organotin(IV)
complexes
Carbon
HL
1
2
3
4
5
1
2/6
4
3/5
7
8
9,9ꢁ
10,10ꢁ
11
12
136.0
128.1
127.8
136.0
167.4
129.1
125.6
114.2
127.7
174.7
136.7
128.4
127.5
136.7
167.6
129.2
124.2
114.0
127.5
175.8
136.4
128.0
127.2
136.6
167.5
129.9
124.3
114.3
127.3
175.2
136.2
128.7
127.7
136.5
167.3
129.3
124.5
114.1
127.6
175.5
136.8
128.6
127.4
136.2
167.9
129.3
124.4
114.4
127.7
175.7
136.5
128.5
127.1
136.4
167.2
129.7
124.8
114.7
127.2
175.9
aCompound 1: Sn-CH3, (C−α) 29.6. δ 119Sn = –27.6. Compound 2: Sn-CH2CH2CH2CH3, (C−α) 29.6 [597],
(C−β) 26.8, (C−γ ) 26.3, (C−δ) 14.1. δ 119Sn = –136.6. Compound 3: Sn-CH2CH2CH2CH2CH2CH2CH2CH3,
(C−α) 33.4 [583], (C−β) 32.7, (C−γ ) 30.6 [92.1], (C−δ) 29.6, (C−α∗) 29.1, (C−β∗) 26.7, (C−γ ∗) 22.4, (C−δ∗)
14.0. δ 119Sn = –139.3. Compound 4: Sn CH2CH2CH2CH3, (C−α) 29.6 [358], (C−β) 27.8 [22.1], (C−γ ) 26.8
3J[64.0], (C−δ) 14.1. δ 119Sn = +80.0. Compound 5: Sn-C6H5, (C−α) 137.2, (C−β) 136.8, (C−γ ) 135.7, (C−δ)
130.4. δ 119Sn = –98.30.
bChemical shifts (δ) in ppm: nJ[119Sn, 13C] in Hz is listed in square brackets.
c
O
O
R
11
8
NH
1
C
C
O
Sn
R
7
12
9
R
Cl
Cl 9
2
6
10
10
3
5
4
Cl
Rꢁ = R for triorganotin, Rꢁ = L for diorganotin.
resonances of the carboxylic carbons in organotin compounds showed downfield shift
(175.9–175.2 ppm) as compared to ligand (174.7 ppm), suggesting the coordination of the
ligand through the carboxylic oxygen, to the organotin(IV) moiety.
For the tri-n-butyltin(IV) derivative, with the 1J[119Sn 13C] value being 350.6 Hz and
by the use of the Holecek and Lycka equation,19 a C Sn C value of 112.3◦ was calculated,
which corresponds to a quasi-tetrahedral geometry in CDCl3 solution (data are given in
Table V). The geometric data calculated, as just described, are consistent with tetrahedral
geometries for the triorganotin(IV) species, i.e., monomer in solution. In all complexes,
119Sn NMR spectra show only a sharp singlet, indicating the formation of a single species.
Table V (C−Sn−C) angles (◦) based on NMR parameters for organotin complexes of 2-[(2ꢁ,4ꢁ,6ꢁ-
trichlorophenylamido)]benzoic acid
Angle (◦)
Compound No.
1J[119Sn, 13C] (Hz)
2J[119Sn, 1H] (Hz)
1J
2J
1
2
3
4
—
81
81
—
—
—
132.1
132.1
—
597
583
358
134.6
133.3
112.3
—

2050
S. SHAHZADI ET AL.
The 119Sn chemical shifts δ(119Sn) of organotin compounds cover a range of over 600 ppm
and are quoted relative to tetramethyltin as a reference. As the electron-releasing power
of the alkyl group increases, the tin atom becomes progressively more shielded, and the
δ(119Sn) value moves to higher field. These values are also dependent on the nature of
X in RnSnX4–n and generally move to lower field as the electronegativity of the latter
increases. A very important property of the 119Sn chemical shift is that an increase in the
coordination number of tin from four to five, six, or seven usually produces a large upfield
shift of δ(119Sn).20 In triorganotin(IV) complexes, 119Sn chemical shift values lie in the
tetrahedral region in non-coordinating solvents, whereas diorganotin(IV) compounds show
a higher coordination, probably five. These values are strongly dependent on the nature and
orientation of the organic groups bonded to tin. The shifts observed in complexes can be
explained quantitatively in terms of an increase in electron density on the tin atom as the
coordination number increases.20
Semi-Empirical Study
In all five structures 1–5, the carboxylate group binds in an anisobidentate mode to
the Sn atom. The bond lengths and angles are similar to those in the literature.21 In 1, the
Sn atom is 2.012 and 2.709 Å away from the oxygens of one of the carboxylic group, while
the other oxygens of the carboxylic group are 2.011 and 2.712 Å away. The long and the
short bonds are trans to each other. The C O bond are also unequal (1.316, 1.239 Å and
1.314, 1.238 Å), the shorter C O bond corresponding to the weakly coordinating oxygens.
The two methyl groups are equidistant from Sn (2.079, 2.079 Å) and are in trans position.
The optimized structure is shown in Figure S1 (Supplemental Materials).
Similarly in compound 2, the displacement of the Sn atom from the O atoms of the
carboxylic acid groups are 2.014 and 2.710 Å away from one of the carboxylic groups,
while the other carboxylic group is 2.014 and 2.720 Å. The long and the short bonds are
trans to each other. The C O bonds are also unequal, being 1.239 and 1.316 Å for both the
ligands, with the longer Sn O bond associated with the shorter C O bond. The two butyl
groups are equidistant from Sn (2.108, 2.107 Å) and complete the coordination sphere of
Sn. The optimized structure is shown in Figure S2 (Supplemental Materials). In 3, again the
Sn atom is asymmetrically attached to the carboxylic acid with displacement of the Sn atom
from the O atoms being 2.015, 2.701 Å and 2.014, 2.717 Å. The long and the short bonds
are cis to each other. The C O bonds are also unequal, being 1.239 and 1.316 Å and 1.239
and 1.315 Å, with the shorter C O bond for the weakly coordinated longer Sn O. The
two octyl groups are equidistant from Sn (2.111 Å, 2.113 Å) and complete the coordination
sphere of Sn. The optimized structure is shown in Figure S3 (Supplemental Materials). In
4, the Sn atom is asymmetrically attached to the carboxylic acid with displacement of the
Sn atom from the O atoms being 2.028, 2.737 Å. The C O bonds are also unequal, being
1.237 and 1.317 Å, with the shorter C O bond for the weakly coordinated longer Sn O.
The three butyl groups are equidistant from Sn (2.133, 2.135, 2.138 Å) and complete the
coordination. The optimized structure is shown in Figure S4 (Supplemental Materials). In
5, the Sn atom is asymmetrically attached to the carboxylic acid with displacement of Sn
atom from the O atoms being 2.11, 2.793 Å. The C O bonds are also unequal, being 1.235
and 1.316 Å with the shorter C O bond for the weakly coordinated longer Sn O. The
three phenyl groups are nearly equidistant from Sn (2.064, 2.065, 2.071 Å) and complete
the coordination. The selected bond lengths and angles of the optimized structure are shown
in Table S2 (Supplemental Materials). The optimized structure is shown in Figure S5.

ORGANOTIN(IV) COMPLEXES
2051
CONCLUSION
Organotin(IV) complexes of 2-[(2ꢁ,4ꢁ,6ꢁ-trichlorophenylamido)]benzoic acid have
been synthesized in anhydrous toluene and characterized by various analytical and spectro-
scopic techniques. The IR data indicate that in both di- and triorganotin(IV) carboxylates,
the ligand moiety COO acts as a bidentate group in solid state, which is also confirmed
by semi-empirical study. Semi-empirical study shows that in the compounds 1–5, the car-
boxylate group binds in an anisobidentate mode to the Sn atom. Spectral studies of reported
complexes in solution state indicate that their structures are tetrahedral for triorganotin(IV)
complexes, while the polymeric structure was exhibited by the diorganotin(IV) complex,
which has a penta-coordinated geometry around the tin atom.
EXPERIMENTAL
Glass apparatus with standard quick-fit joints were used throughout the work after
cleaning and drying at 120 ◦C. Phthalic anhydride and organotin(IV) chlorides were pur-
chased from Aldrich Chemical Company (USA), while dioctyltin oxide was procured from
Alfa Aesar (USA) and used as such. Glacial acetic acid, toluene, acetone, dichloromethane,
diethyl ether, methanol, and chloroform were obtained from Merck Chemicals (Germany).
All solvents were purified and dried by the reported methods.22 Melting points were deter-
mined on an electrothermal melting point apparatus, model MP-D Mitamura Riken Kogyo
(Japan) by using capillary tubes and are uncorrected. Elemental analysis was carried out
on a Perkin-Elmer 2400 analyzer (USA). Infrared spectra were recorded as KBr pellets on
a 1000 Perkin Elmer instrument in the range 4000–250 cm−1. Mass spectra were recorded
1
on a MAT 8500 Finnigan (Germany). The H and 13C NMR spectra were recorded on a
Bruker AM-250 using CDCl3 as an internal reference. 119Sn NMR spectra were obtained
on a Bruker 250 ARX instrument with Me4Sn as an external reference.
The structure of complexes 1–5 were modeled by the MOPAC 200723 program using
the PM6 method.24 Selected parts of the molecule not containing the metal ion were
preoptimized using the molecular mechanics method before subjecting the whole molecule
to geometry optimization.
General Procedure for the Synthesis of Carboxylic Acid
Carboxylic acid has been synthesized by the method in the literature.25 Detail of the
procedure is as follows:
A solution of phthalic anhydride (1 mmol) in a HOAc (300 mL) was added to a
solution of substituted aniline (1 mmol) in a HOAc (150 mL) in a 1 L round bottom flask,
and the mixture was stirred at room temperature overnight. The precipitates formed were
filtered, washed with cold distilled water (200 mL), and air dried [Equation (1)]. Yield =
95%.
O
O
C
O
C
C
i) Glacial acetic acid
ii) Overnight stirring
(1)
O
R
NH2 +
R
NH
OH
C
O

2052
S. SHAHZADI ET AL.
Where
Cl
Cl
R =
Cl
General Procedure for the Synthesis of Organotin(IV) Complexes
from Organotin(IV) Chloride
The synthesized carboxylic acid (10 mmol) was suspended in dry toluene (100 mL)
and treated with triethylamine in a 1:1 molar ratio. The mixture was refluxed for 2–3 h.
To a solution of triethylammonium salt of the ligand in dry toluene (100 mL), diorganotin
dichloride (5 mmol) or triorganotin chloride (10 mmol) was added as a solid to a reaction
flask with constant stirring, and the reaction mixture was refluxed for 8–10 h. The reaction
mixture was contained Et3NHCl and was filtered. The filtrate contained the organotin(IV)
derivative. The solvent was removed in a rotary apparatus under reduced pressure. The
residue was recrystallized from CHCl3 and ether (1:1) [Equations (2) and (3)].
i) Toluene
R2SnCl2 + 2Et3NHL −−−−−−−−−−−→ R2SnL2 + 2Et3NHCl
(2)
(3)
ii) Reflux for 8−10 hrs
i) Toluene
R3SnCl + Et3NHL −−−−−−−−−−−→ R3SnL + Et3NHCl
ii) Reflux for 8−10 hrs
From Organotin(IV) Oxide
The synthesized carboxylic acid (10 mmol) was suspended in dry toluene (100 mL)
and treated with organotin oxide (5 mmol) in a reaction flask with constant stirring. Then
the mixture was refluxed for 8–10 h. Water formed was removed via a Dean–Stark trap.
After completion and cooling the reaction mixture to room temperature, the solvent was
removed in a rotary apparatus under reduced pressured. The residue was recrystallized from
CHCl3 and ether (1:1) [Equation (4)].
i) Toluene
R2SnO + 2HL −−−−−−−−−−−→ R2SnL2+H2O
(4)
ii) Reflux for 8−10 hrs
Where
R2
R3
Me2
Bu2
Oct2
(1)
–
–
(2)
Bu3
(4)
(3)
Ph3
(5)
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