Synthesis and spectral studies of di- and triorganotin(IV) complexes with 2-(6-methoxynaphthyl)propionic acid (naproxen)

Article abstract of DOI:10.1081/SIM-120003213

Complexes of the composition R_4-nSnL_n (R=Me, Et, Bu, Ph, Bz, n=1 and 2, and L=2-(6-methoxynaphthyl)propionic acid anion have been synthesized by the reaction of tri- and diorganotin halides with the silver salt of 2-(6-methoxynaphthy

Full text of DOI:10.1081/SIM-120003213

Synthesis and Reactivity in Inorganic and Metal-Organic
Chemistry
ISSN: 0094-5714 (Print) 1532-2440 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt19
SYNTHESIS AND SPECTRAL STUDIES OF DI-
AND TRIORGANOTIN(IV) COMPLEXES WITH
2-(6-METHOXYNAPHTHYL)PROPIONIC ACID
(NAPROXEN)
Saqib Ali , Fiaz Ahmad , M. Mazhar , Arshad Munir & M. Tariq Masood
To cite this article: Saqib Ali , Fiaz Ahmad , M. Mazhar , Arshad Munir & M. Tariq Masood (2002)
SYNTHESIS AND SPECTRAL STUDIES OF DI- AND TRIORGANOTIN(IV) COMPLEXES WITH 2-(6-
METHOXYNAPHTHYL)PROPIONIC ACID (NAPROXEN), Synthesis and Reactivity in Inorganic and
Metal-Organic Chemistry, 32:2, 357-372, DOI: 10.1081/SIM-120003213
To link to this article: http://dx.doi.org/10.1081/SIM-120003213
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Date: 28 January 2016, At: 10:27

SYNTH. REACT. INORG. MET.-ORG. CHEM., 32(2), 357–372 (2001)
SYNTHESIS AND SPECTRAL STUDIES
OF DI- AND TRIORGANOTIN(IV)
COMPLEXES WITH
2-(6-METHOXYNAPHTHYL)PROPIONIC
ACID (NAPROXEN)
Saqib Ali,1,* Fiaz Ahmad,1 M. Mazhar,1 Arshad Munir,2
and M. Tariq Masood3
1Department of Chemistry, Quaid-I-Azam University,
Islamabad, Pakistan
2Pakistan Atomic Energy Commission, P. O. Box. 1331,
Islamabad, Pakistan
3Islamabad College for Boys G-6=3, Islamabad,
Pakistan
ABSTRACT
Complexes of the composition R4-nSnLn (R ¼ Me, Et, Bu, Ph,
Bz, n ¼ 1 and 2, and L ¼ 2-(6-methoxynaphthyl)propionic
acid anion have been synthesized by the reaction of tri- and
diorganotin halides with the silver salt of 2-(6-methox-
ynaphthyl)propionic acid in dry chloroform. Conductance
data show that the complexes are non-electrolytes. Structural
assignments were made on the basis of spectral studies (FTIR,
1H, 13C, 119Sn NMR, mass and UV-Vis spectroscopy).
*Corresponding author. E-mail: drsa54@yahoo.com
357
Copyright # 2002 by Marcel Dekker, Inc.
www.dekker.com

358
ALI ET AL.
INTRODUCTION
Organotin compounds show a large spectrum of biological activity but
mainly are used commercially as industrial and agricultural biocides because
of their antifungal properties1. Some organotins are currently being inves-
tigated for antitumour activity2. Some R3SnL derivatives (L ¼ monodentate
or bidentate ligand) are highly toxic3–8, while diorganotin(IV) derivatives
like diethyltin(IV) and dibutyltin(IV) carboxylates are known anti-tumor
agents9–12. In various studies it has been suggested that ligand replacement
changes the toxicity of the organotin moiety3–8, because it has been assumed
that, eventually, coordinated organic ligands would facilitate the transport
of the potentially active R2Sn2þ moiety to the site of action, where it is
released by hydrolysis. If the compound is hydrolytically unstable, the
R2Sn2þ species is released too early and reacts at unsuitable sites; if it is too
stable, it may be released too late or very slowly for the activity to be
effective13.
In order to explore their biological activity, we have prepared a series
of organotin carboxylates of 2-(6-methoxynaphthyl)propionic acid com-
monly known as Naproxen, one of the most frequently used analgesic,
antipyretic and anti-inflammatory drugs14–16. In the accessible literature, no
organotin(IV) derivatives have been synthesized so far.
In this paper we report the synthesis and spectral properties of tri- and
diorganotin derivatives of Naproxen (Fig. 1)
RESULTS AND DISCUSSION
Complexes of di- and triorganotin chlorides with 2-(6-methoxynaph-
thyl)propionic acid (Naproxen) have been synthesized by mixing dry
chloroform solutions of the respective organotin compound and the silver
Figure 1. Numbering scheme and structure of 2-(6-methoxynaphthyl)propionic
acid (naproxen).

ORGANOTIN COMPLEXES OF NAPROXEN
359
salt of the ligand in 1:1 and 1:2molar ratios. The preparation of the com-
plexes may be represented by the following general equations.
R3SnCl þ AgLÀ! R3SnL þ AgCl
½R ¼ Bu ð2Þ; Me ð4Þ; Ph ð7Þ; Bz ð9ފ
R2SnCl2 þ AgLÀ! R2SnL2 þ 2AgCl
½R ¼ Bu ð1Þ; Me ð3Þ; Et ð5Þ; Ph ð6Þ; Bz ð8ފ
All the newly synthesized complexes are quite stable to air and are
creamy white, crystalline solids, which are mostly soluble in common
organic solvents. The complexes were sufficiently soluble in absolute ethanol
to enable their molar conductivity measurements. The molar conductivity of
10À3 M solutions of the complexes is in the range of 2–15 mS=cm2, which
indicates their non-electrolytic nature17 (Table I).
Electronic Spectra
The electronic spectra for the ligand and its complexes were recorded
in absolute ethanol. The bands are derived from interligand and charge
transfer or (n ? p*) transitions. The UV spectra of the complexes are similar
to that of the ligand and show very little or no shifts in the positions of the
absorption maxima. The bands near 285 and 270 nm are assigned to
interligand (p ? p*) transitions for the aromatic moiety of the ligand18.
Further, a few sharp absorption bands were observed in the region
2407270 nm in the spectra of the complexes which could be assigned as
charge transfer (L ? M)19 or (n ? p*) transition20.
Infrared Spectra
Infrared spectra of the di- and triorganotin(IV) derivatives of 2-(6-
methoxynaphthyl)propionic acid have been recorded in the range of
4000–250 cmÀ1 as KBr disc and important bands are given in Table II.
The broad band in the range of 3189–3140 cmÀ1 due to n(OH) present
in the acid ligand is absent in the spectra of its silver salt and the corre-
sponding di- and triorganotin(IV) derivatives.
In case of diorganotin carboxylates, the most important bands
observed for n(COO)asym and n(COO)sym occur at 158071630 cmÀ1 and

360
ALI ET AL.

ORGANOTIN COMPLEXES OF NAPROXEN
361
Table II. Infrared Dataa (cmÀ1) for Organotin Derivatives of Naproxen
n(COO)
No
Compounds
asym
sym
Dn
n(Sn-C)
n(Sn-O)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
L
Bu2SnL2
Bu3SnL
Me2SnL2
Me3SnL
Et2SnL2
Ph2SnL2
Ph3SnL
Bz2SnL2
Bz3SnL
Ligand
1628 s
1610 s
1602 s
1593 s
1596 s
1610 s
1628 s
1587 s
1628 s
1674 s
1665 s
1380 s
1320 s
1381 s
1344 s
1380 s
1413 s
1399 s
1389 s
1399 s
1453 s
1389 s
248
290
221
299
216
197
229
198
229
220
276
545 s
520 m
541 s
553 s
536 s
510 s
560 s
536 m
536 w
–
474 s
472 s
479 w
477 m
479 s
477 s
452 s
475 s
478 s
–
L-Ag
Ligand-Ag
–
–
as, strong; m, medium; w, weak.
132071420 cmÀ1, respectively (Table II). The Dn value [Dn ¼ n(COO)asym
À
n(COO)sym] has been utilized to identify the mode of carboxylate interac-
tion. According to the earlier reports, if this value is comparable to that of
the silver salt of the acid ligand, then the carboxylate ion behaves as a
bidentate chelate group. It is, therefore, suggested that the carboxylate
group in these compounds is acting as a bidentate ligand21–23 (Fig. 4). The
bands in the range of 5107545 cmÀ1 and 4507480 cmÀ1 indicate the Sn-C
and Sn-O bonds, respectively.
Multinuclear NMR Spectra
1
The H NMR spectral data in CDCl3 solution of the acid and com-
plexes are listed in Tables III and IV. The absence of the COOH proton
resonance in the compounds shows that organotin carboxylates have been
formed. A complex multiplet due to the aromatic protons of the phenyl
group (both in the ligand and phenyltin) is observed in the range of
7.13–7.73 ppm. The resonance assigned to butyltin protons fall in the region
of 0.72–1.60 ppm.
The methyl protons of the di- and trimethyltin derivatives appear as
sharp singlets with coupling satellites from tin. The coupling constant
2J(119Sn-1H) provides valuable information about hybridization24,25. For
2
four-coordinated methyltin(IV) compounds, J(119Sn-1H) values have been

362
ALI ET AL.

ORGANOTIN COMPLEXES OF NAPROXEN
363

364
ALI ET AL.
reported, which increase as the coordination number of tin increases from
four to five to six or seven depending upon the stereochemistry26–28. For
2
trimethyltin derivative J[119Sn-1H] ¼ 57.13 Hz falls in the range of tetra-
hedral environment29, which is further supported by the C-Sn-C bond angle
(111.0ꢀ) calculated using Lockhart’s equation29. In case of n-butyl, phenyl
n
and benzyl derivatives the J[119Sn-1H] couplings are not visible due to a
complex multiplet pattern.
13C NMR spectral data in CDCl3 solutions of the acid ligand and of the
compounds are given in the Tables V and VI. The number of signals found
corresponds to the presence of expected magnetically nonequivalent carbon
atoms. The position of the aromatic carbon signals remains unchanged in the
complexes as compared to that of the ligand acid. The position of the car-
boxylate carbon in all of the complexes shifts to lower field as compared to
the free acid indicating the participation of carboxylate group in coordina-
tion to tin(IV)30. In the butyl complexes there are four types of magnetically
non-equivalent carbons. The identification of alkyl=phenyl carbons in all the
1
complexes along with J values confirms the complexation.
Table V. 13C NMR Dataa,b,c of Diorganotin Derivatives of Naproxen
Compound
13C No.
L
(1)
(3)
(5)
(6)
Naproxen Bu2SnL2 Me2SnL2 Et2SnL2 Ph2SnL2 Bz2SnL2
(8)
1
181.0
45.8
n.o 185.20
45.58 48.4145.72 38.36
185.49
183.46
184.71
18.91
245.5
3
18.6
55.80
127.60
119.5
129.3
106.0
135.4
126.5
158.1
134.2136.18
–
19.17
55.80
19.26
55.77
19.31
55.76
18.67
55.7255.69
127.57
118.99
129.29
105.95
135.93
126.68
157.83
135.97
143.75
137.69
133.96
129.76
–
4
10
127.50
119.29
129.22
105.93
134.13
126.64
156.99
127.66
119.43
129.34
105.98
134.14
126.50
158.06
127.55
119.36
129.33
105.97
134.13
126.59
158.01
135.93
18.09
9.25
127.45
119.31
128.53
105.99
134.15
126.59
158.03
20
300,80
4
400
500,70
6
800
a
b
g
d
e
135.93
136.13
24.15
26.89
26.34
13.81
–
14.53
32.27
124.37
128.87
126.33
125.79
–
–
–
–
–
–
–
–
–
–
aChemical shifts (d) in ppm.
bNumbering is according to Fig. 1.
cSee footnotes of Table III for a, b, g, d, e.

ORGANOTIN COMPLEXES OF NAPROXEN
365
Table VI. 13C NMR Dataa,b,c of Triorganotin(IV) Derivatives of Naproxen
Compound
13C No.
(2)
Bu3SnL
(4)
Me3SnL
(7)
Ph3SnL
(9)
Bz3SnL
1
246.67
3
180.37
46.51
180.55
.5426.04
19.91
181.48
n.o
42
19.67
55.7255.74
127.03
119.03
129.37
105.93
133.89
126.16
157.76
137.77
27.39
19.86
18.90
4
55.71
55.56
10
127.34
119.14
129.38
105.96
133.89
126.17
157.83
137.66
À1.94 [390]
–
127.04
119.16
129.30
106.00
133.99
126.23
157.93
133.58
137.23
138.73
130.52
128.79
–
127.42
119.45
129.04
106.00
129.74
126.57
158.00
132.56
32.78
129.29
128.77
126.32
125.65
20
30, 80
40
400
50,70
60
800
a
b
g
d
e
27.91
28.17
14.05
–
–
–
–
1
aChemical shifts (d) in ppm. J(119Sn-13C) in Hz in parentheses.
bNumbering is according to Fig. 1.
cSee footnotes of Table III for a, b, g, d, e.
Table VII. 119Sn NMR Data for Organotin(IV) Derivatives of Naproxen
Compound No.
Compounds
119Sn NMR
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Bu2SnL2
Bu3SnL
Me2SnL2
Me3SnL
Et2SnL2
Ph2SnL2
Ph3SnL
Bz2SnL2
Bz3SnL
À146.15
111.137
n. p.a
135.449
À152.03
À223.120
À108.90
À246.34
33.929
an. p. (not performed).

366
ALI ET AL.
The chemical shifts d 119Sn (Table VIII) for triorganotin carboxylates
are comparable with shift earlier reports describing tetrahedral geometry31,32
.
In diorganotin(IV) derivatives d 119Sn chemical shifts reveal a coordination
number greater than 5 for tin as reported earlier30.
Mass Spectrometry
The mass fragmentation patterns of the diorganotin and triorganotin
carboxylates are given in Figs. 2and 3, respectively. A molecular ion peak of
reasonable intensity was observed in almost all of the compounds except the
phenyl derivatives. In the triorganotin derivatives primary fragmentation is
due to the loss of an R group, while the secondary fragmentation occurs by
the elimination of either R or CO221,33. In case of the diorganotin deriva-
tives, the primary fragmentation is mostly by the loss of one ligand and CO2
is eliminated in a second step. If the primary fragmentation is due to the loss
of an R group, then there is a successive elimination of two CO2 molecules.
There is another route for the fragmentation of diorganotin in which
primary fragmentation occurs by the loss CO2, while the secondary
fragmentation is due to the loss of a ligand molecule followed by the loss of
two R groups. The base peak of the ligand moiety [C13H13O]þ is observed in
Table VIII. Mass Fragmentation Pattern for Diorganotin(IV) Derivatives of
Naproxen
Fragmentation
(1) Int.(%) (3) Int.(%) (5) Int.(%) (6) Int.(%) (8) Int.(%)
[R2SnC28H26O6]þ 6925 608
10 636 n.o 73n2.o 760
25 407 100 503
8
12 531
[R2SnC14H13O3]þ 463
[RSnC14H13O3]þ 406
45 379
20
5
5
5
364
349
305
10 378
2349
2642
38 349
1
440
18 349
52
[SnC14H13O3]þ
[SnC13H13O]þ
[C13H13O]þ
[C14H13O3]þ
[R]þ
349
305
18
5
305
10 305
22 305
18
65
40
185 100 185 100 185 100 185 100 185
229
58
10 229
3
3
8
1
229
30
12 229
278
38 229
91 32
15
379
8
[R2SnC13H13O]þ 419
25 363
1
459
–
487
–
[RSnC13H13O]þ 36210 32n.o 334 n.o 3826 396
10
[Snþ=SnH]þ
120
6
8
6
2578
2534
120
593
564
2
120 n.o 120
20 655
688
5
8
120
668
716
10
10
8
[RSnC28H26O6]þ 635
[R2SnC27H26O4]þ 648
18 607
22 592
–
–
[SnC28H26O6]þ
[SnC27H26O4]þ
578
574
10 578
534
18 578
10 534
10 578
534
8
8
8
8

ORGANOTIN COMPLEXES OF NAPROXEN
367
Figure 2. Fragmentation pattern of R2SnL2.
Figure 3. Fragmentation pattern of R3SnL.

368
ALI ET AL.
Figure 4. Proposed structures (a), (b), (c) for triorganotin (IV) carboxylates and (d),
(e) for diorganotin (IV) carboxylates.
Table IX. Mass Fragmentation Pattern for Triorganotin(IV) Derivatives of
Naproxena
Fragmentation
(2) Int.(%) (4) Int.(%) (7) Int.(%) (9) Int.(%)
[C14H13O3SnR3]þ 520
[C14H13O3SnR2]þ 463
20
85
5
394
379
335
305
165
150
135
185
120
229
15
5
5
580
503
459
n.o
2531
–
622
487
10
1
65
[C14H13OSnR2]þ
[C13H13OSn]þ
[R3 Sn]þ
419
305
291
234
177
185
120
229
57
4
2305
8
8
5
8
16
305
8
16
18
16
100
2
10
8
2350
351
274
197
185
120
229
77
85
10
20
100
18
28
18
393
302
211
185
120
229
91
2
5
8
100
1
10
20
[R2 Sn]þ
[R Sn]þ
[C13H13O]þ
[SnHþ=Sn]þ
[C14H13O3]þ
[R]þ
100
2
2
1
[C13H13OSnR3]þ
476
5
536
12 578
48
an.o ¼ not observed.

ORGANOTIN COMPLEXES OF NAPROXEN
369
almost all compounds. The peaks for [R3Sn]þ and [R2Sn]þ have either very
low intensities or are absent, which indicates that fragmentation through
these species is not favourable21,34
.
EXPERIMENTAL
All the di- and triorganotin halides except benzyl derivatives, were
procured from Aldrich or Fluka while the di- and tribenzyltin chlorides were
prepared by the reported method35. All the solvents were dried before use36.
General Procedure for the Synthesis
To a suspension of the silver salt of 2-(6-methoxynaphthyl)propionic
acid (2.303 g, 0.01 mol) in dry chloroform (25 mL) in a 250 mL two-necked
round bottom flask equipped with a water condenser and magnetic stirring
bar, triorganotin chloride (0.01 mol) or diorganotin dichloride (0.005 mol) in
dry chloroform (25 mL) was added dropwise with constant stirring. The
reaction mixture was refluxed for 7–8 h, in an inert atmosphere and then was
allowed to stand overnight at room temperature. The silver chloride formed
was filtered off and the solvent was removed under reduced pressure. The
solid mass left was recrystallized in dichloromethan=n-hexane (1:1).
Instrumentation
Melting points were determined in a capillary tube using a MPD
Mitamura Riken Kogyo (Japan) electrothermal melting point apparatus.
Infrared absorption spectra were recorded as KBr pellets on a Perkin Elmer
FT-IR (model Spectrum 1000) spectrometer. 1H, 13C and 119Sn NMR
spectra were recorded on a Bruker AM 250 spectrometer (Germany) using
CDCl3 as an internal reference [d 1H(CDCl3) ¼ 7.23 ppm:
d
13C
(CDCl3) ¼ 77.0 ppm]. 119Sn NMR spectra were obtained on a Bruker
250ARX spectrometer (Germany) with Me4Sn [(Sn) ¼ 37.296665 ppm] as an
external reference. Mass spectral data were measured on a MAT 8500
Finnigan mass spectrometer (Germany). UV absorption spectra were
recorded on a Perkin Elmer UV-Vis Lambda 2S instrument, while con-
ductance measurements were made on a Model DDS-11A (China) con-
ductometer.

370
ALI ET AL.
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Received February 17, 2000
Accepted November 29, 2001
Referee I: I. Haiduc
Referee II: J. C. Cochran