Spectroscopic characterizations, structural peculiarities, molecular docking study and evaluation of biological potential of newly designed organotin(IV) carboxylates

Article abstract of DOI:10.1016/j.jphotobiol.2019.111516

In the search for new therapeutic agents we have synthesized 13 new organotin(IV) carboxylate derivatives of (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid. The synthesized complexes were characterized by several spectroscopic techniques. A

Full text of DOI:10.1016/j.jphotobiol.2019.111516

Accepted Manuscript
Spectroscopic
characterizations,
structural
peculiarities,
molecular docking study and evaluation of biological potential of
newly designed organotin(IV) carboxylates
Muhammad Sirajuddin, Saqib Ali, Vickie McKee, Naheed
Akhtar, Saiqa Andleeb, Abdul Wadood
PII:
S1011-1344(19)30458-0
DOI:
https://doi.org/10.1016/j.jphotobiol.2019.111516
Article Number:
Reference:
111516
JPB 111516
To appear in:
Journal of Photochemistry & Photobiology, B: Biology
Received date:
Revised date:
Accepted date:
15 April 2019
30 April 2019
27 May 2019
Please cite this article as: M. Sirajuddin, S. Ali, V. McKee, et al., Spectroscopic
characterizations, structural peculiarities, molecular docking study and evaluation of
biological potential of newly designed organotin(IV) carboxylates, Journal of
Photochemistry
&
Photobiology,
B:
Biology,
https://doi.org/10.1016/
j.jphotobiol.2019.111516
This is a PDF file of an unedited manuscript that has been accepted for publication. As
a service to our customers we are providing this early version of the manuscript. The
manuscript will undergo copyediting, typesetting, and review of the resulting proof before
it is published in its final form. Please note that during the production process errors may
be discovered which could affect the content, and all legal disclaimers that apply to the
journal pertain.

ACCEPTED MANUSCRIPT
Spectroscopic characterizations, Structural peculiarities, Molecular docking study and
evaluation of biological potential of newly designed organotin(IV) carboxylates
Muhammad Sirajuddina,*, Saqib Alib,*, Vickie McKeec, Naheed Akhtard, Saiqa Andleebd,
Abdul Wadoode
a Department of Chemistry, University of Science and Technology Bannu, 28100, Pakistan
b Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan
c Department of Chemistry, Dublin City University, Ireland, UK
d
Department of Zoology, University of Azad Jammu and Kashmir, Muzaffarabad 13100,
Pakistan.
e
Department of Biochemistry, Computational Medicinal Chemistry Laboratory, UCSS, Abdul
Wali Khan University Mardan, Pakistan
*Corresponding author address: m.siraj09@yahoo.com (M. Sirajuddin); drsa54@hotmail.com
(S. Ali)
Abstract
In the search for new therapeutic agents we have synthesized 13 new organotin(IV) carboxylate
derivatives of (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid. The synthesized
complexes were characterized by several spectroscopic techniques. A chelating or bridging
bidentate nature of the carboxylate ligand was suggested from the solid state FT-IR results.
13
Solution state multinuclear NMR (1H, C and 119Sn) results reveal that the geometry around the
Sn atom in triorganotin(IV) complexes is trigonal bipyramidal and in diorganotin(IV) complexes
is octahedral. The ligand, (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid,
complex 1 and complex 2 were also analyzed by single crystal X-ray technique and the results
fully supports the spectroscopic data. For 1 and 2 the geometry optimized by the single crystal
X-ray analyses is distorted trigonal bipyramidal. The interaction of the studied compounds with
SS-DNA was investigated by UV-Vis. Spectroscopy and Molecular docking showing an
intercalative mode of binding. The evaluation of the screened compounds for cancer treatment
displays even higher than that of the vincristine used as a standard drug. Similarly the
performance of the tested compounds as an antileishmanial agent considers them very close in
activity to the standard drug, amphotericin B. The antibacterial results show that the most of the
compounds have a moderate sensitivity against the studied bacterial pathogens.
1

ACCEPTED MANUSCRIPT
Keywords: Organotin(IV) Carboxylate; Spectroscopic Characterization; DNA Interaction Study;
Anticancer Activity; Antileishmanial Activity; Molecular docking
1.
Introduction
Organometallic compounds which contain Sn atom attached to organic moiety with atleast one
direct Sn-C covalent bond are known as organotin(IV) compounds or simply organotins with
general formula of RnSnX4-n; where R is the organic moiety, X is any anionic group like Cl-, OH-
etc. and n = 1-4. Depending on the number of organic moiety (n) attached to Sn atom the
organotin(IV) compounds are classified as: RSnX3, R2SnX2, R3SnX and R4Sn: and are called
mono, di, tri and tetra organotin(IV) compounds, respectively [1]. Organotin(IV) compounds
have lot of applications both on non-biological and biological sides. The non-biological
applications include effective catalyst in the conversion of oil into biodiesel via trans
esterification reaction [2-4], antiseptic agents for marine [5], preservatives for wood [6, 7],
antifouling paints [8], polymer stabilizers [9], curing of silicon, and so forth [10, 11].
On the other hand the biological side covers the vast field of medicinal chemistry due to their
structural diversity and large therapeutic applications [12].
Cancer, which is also known as deadly fatal disease, is the 2nd most common disease after the
cardiovascular disease and is major issue to the human being from a very long time. The cancer
affected patients are increased day by day mainly due the modernization of the society. There are
many available anti cancer drugs in the markets but they posses some serious side effects that
bound their use for affective treatment. Due to these factors the demand for new affective and
less costly drugs is still continued [13].
Anticancer compounds must interact with DNA to stop its replication or transcription by
different ways, although the exact mechanism is till under the investigation [14]. The study of
DNA interaction with organotin(IV) compounds received incredible researcher attention from
the last few years as a result of their good anticancer and antitumor activities [11]. Metal
oxidation state, coordinated ligands, coordination number and geometry mostly affect the target
recognition [15]. DNA is the easy target for the organotins due to their specificity for DNA
sequences resulting in the alteration of the DNA structure leading to the inhibition of the protein
activator or repressor and ultimately influences the gene expression process [16]. The
organotin(IV) compounds have the ability of interaction with DNA which depends on number of
2

ACCEPTED MANUSCRIPT
factors like: geometry of the molecule or coordination number of the Sn atom, nature of the
organic moiety already attached to the Sn atom, nature of the coordinated ligand and ease of the
ligand hydrolysis [11, 17]. Organotin(IV) compounds interact with DNA via different modes
such interaction (in which the planar part of the molecule insert into the DNA bases), groove
binding (in which the compound with L type structure fit itself in the grooves of DNA) and
electrostatic interaction [18].
In the context here we are exploring the designing of 13 new organotin(IV) derivatives based on
(E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic
acid.
Different
instrumental
techniques were used for the characterization of the newly synthesized compounds. The
biological potential of the synthesized compounds were explored against bacteria, DNA, cancer
and leishmania.
2.
Experimental section
2.1. Materials and methods
Reagent grade quality chemicals were obtained from chemical companies (Aldrich and E.
Merck). The required solvents were 1st dried prior to use in accordance to the reported method
[19]. The (C6H5-CH2)2SnCl2 salt was synthesized according to the earlier reported method [20].
Salmon fish sperm DNA (SS-DNA) was purchased from Arcos chemical company in the form of
solid Na+ salt and was used as received.
The following instrument/apparatus were used for the desired purpose: Gallenkamp (UK)
electrothermal melting point apparatus for melting point determination;
Thermo Nicolet-6700
for FT-IR spectra recording; CE-440 Elemental Analyzer for carbon,
FT-IR Spectrophotometer
hydrogen and nitrogen contents measurement; JEOL ECS instrument (400 MHz) for NMR
spectra recording; Shimadzu 1800 UV-Vis. Spectrophotometer for recording absorption spectra
of compound-DNA adduct; Bruker Apex II CCD diffractometer for recording the crystal data;
Thermo Scientific executive mass spectrometer for recording the mass spectra.
Synthesis
Synthesis of (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid (HL)
(E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid (HL) was prepared by reacting
10 mmol (2.66 g) of 4-methoxy-2-nitroaniline dissolved in glacial CH3COOH with 10 mmol
3

ACCEPTED MANUSCRIPT
(0.98 g) maleic anhydride dissolved in glacial CH3COOH (Scheme 1) according to our earlier
reported procedure [21].
Synthesis of Sodium (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoate (NaL)
Sodium (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoate (NaL) was prepared by
reacting the aqueous solution of sodium hydrogen carbonate (NaHCO3) with suspended solution
of (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid in distilled water. After
mixing the reactants and stirring them at room temperature, a clear solution was obtained that on
rotary evaporation of the solvent gives the desired NaL product [22] as shown in Scheme 1.
Synthesis of complexes
Sodium (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoate (NaL) was used for the
preparation of complexes while reacting with different salts of organotins in different molar ratio
of NaL and organotin(IV) chlorides in dried toluene solvent and refluxing for 6-8 hours. i.e., for
the synthesis of triorganotin(IV) complexes the molar ratio of NaL and R3SnCl (R = CH3, C2H5,
C4H9, C6H5 and C6H11) was 1:1 while for the synthesis of diorganotin(IV) complexes the molar
ratio of NaL and R2SnCl2 (R = CH3, C4H9, C6H5, C6H5-CH2 and C2H3) was 2:1. Dioctyltin
complex was prepared with the same molar ratio while using HL instead of NaL and
(C8H17)2SnO (Scheme 1) [22]. After the completion of reaction the reaction mixture was
filtered to remove the byproduct NaCl and the toluene was evaporated by rotavapor to get the
required product which was then recrystallized in chloroform at room temperature.
4

ACCEPTED MANUSCRIPT
Scheme 1: Synthetic scheme for the preparation of HL, NaL and organotin(IV) complexes along
with atom numbering of HL and organic moieties attached to Sn atom
5

ACCEPTED MANUSCRIPT
2.2. Electronic absorption titration for DNA binding
Compound-DNA binding was carried out by UV-Vis. Spectroscopy according to the earlier
reported method [23, 24]. The tested samples were prepared in 70% ethanol at a concentration of
1 mM. A constant concentration of compounds (1 mM) was treated with varying concentrations
of SS-DNA (9-72 µM) at room temperature (25 ± 1 °C). The most shifted peak absorbencies of
the compound was noted after the successive additions of DNA. The absorbance of the reference
cell was made nil by using the same concentration of DNA in the reference cell also.
2.3. Anticancer Activity
The anticancer potential of the synthesized compounds was evaluated against two cancer cell
lines: H-157 and BHK-21 cells according the Skehan's method [25] of SRB (Sulforhodamine B)
with some modifications [21, 26]. Different concentrations of compounds were prepared (100,
10, 1 and 0.1 µM) and were transferred to test wells. Control and blank wells were also prepared
containing standard drug (Vincristine) and culture media with cells, respectively.
2.4. Antileishmanial activity
The compounds were evaluation of antileishmanial potential against Leishmania major according
to the earlier reported method [22, 27]. From different concentrations of compound, 10 μL/well
was transferred to triplicate wells. For the antileishmanial activity assays, 100 μL/well of the
culture which contained 2.5×106 cells/mL promastigotes was seeded in 96-well flat-bottom
plates. Then 10 μL/well from various concentrations of compounds were added to triplicate wells
and plates were incubated for 72 h at 25 ± 1 °C. The first well of 96 wells was as a blank well
which only contained of 100 μL culture medium without any compound, drug or parasite.
Amphotericin B was used as standard drug. The experiments were performed in triplicate and
results reported in the form of mean of three independent experiments (± SEM) and expressed as
percent inhibitions calculated by the formula [22, 27]:
2.5. Antibacterial activity assay
Determination of the antibacterial activity was carried out by agar well-diffusion method [28]
against seven human clinical bacterial pathogens viz., E. coli, S. marcesscens, K. pneumoniae, S.
epidermidis, S. pyogenes, P. aeruginosa and S. aureus. After 24 h, culturing flask containing
bacterial strains were poured aseptically in 100 mL flask containing nutrient agar medium, gently
6

ACCEPTED MANUSCRIPT
mixed and poured in Petri dishes. Petri plates were allowed to solidify under laminar flow to
avoid contamination. Six wells per plate were made with sterile yellow tip of (5mm) and 30 µL
of each compound was poured aseptically in wells. For each sample triplicate plates were
prepared. After 24 hours incubation at 37 ºC the zone of inhibition around each well was
observed and determined using scale in millimeters [29]. Antibacterial activities were calculated
as a mean of three replicates. Diameter of the clear zones (> 5 mm) showed bacterial growth
around each well [22].
2.6. Molecular docking
MOE “Molecular Operating Environment” (version 2016) [30] software was used for obtaining
the 3D figures of the newly synthesized organotin(IV) carboxylates. With the help of 3D
protonation, the H atoms to the synthesized compounds were added followed by energy
optimization using MOE. Crystal structure of the Salmon sperm-DNA was retrieved using PDB
(protein databank) with id: 1BNA) [www.rcsb.org/pdb]. With the help of MOE software
(www.chemcomp.com) all the H2O molecules were eliminated from the retrieved structure of
DNA prior to molecular docking. The 3D protonation and energy minimization of the retrieved
DNA was performed using MOE software having the default parameters. Docking of the
macromolecule (DNA) with the synthesized compounds was done with MOE with default
parameters i.e., Placement: Triangle Matcher, Rescoring: London dG. 10 conformations were
generated for each compound and the top-ranked conformation of each compound was used for
further analysis.
3. Results and discussion
The ligand was synthesized by an easy and economical method by treating aniline and maleic
anhydride in beaker at room temperature and within a very short time of 3-5 minutes the
precipitate of the resulting compound appeared. The precipitate was washed several times with
distilled water and then air dried. The ligand and its organotin(IV) derivative were prepared in
good yield and they were both light and air stable in light and dry air. They were freely soluble in
solvents such as CHCl3, CH3OH, C2H5OH and (CH3)2SO etc. Table 1 presents the %age yield of
the product, M.P, CHN (carbon, hydrogen, nitrogen) contents etc of the newly prepared
compounds. It can be seen from the data in Table 1 that a very good matching was observed
7

ACCEPTED MANUSCRIPT
between the experimentally and theoretically found values of carbon, hydrogen, nitrogen
contents.
8

ACCEPTED MANUSCRIPT
Table 1: Physical and elemental composition data (%) of the synthesized compounds*
Comp. No
%age
Yield
Melting
Formula
weight
Formula
Carbon,
Hydrogen,
Nitrogen,
point (°C)
calculated/found
calculated/found calculated/found
93
90
85
76
85
85
75
80
80
75
75
87
80
78
134-136
151-152
113-115
68-70
266.2
429.0
471.1
555.3
612.2
633.4
679.2
763.3
803.3
846.4
703.2
875.5
585.2
609.2
C11H10N2O6
C14H18N2O6Sn
C17H24N2O6Sn
C23H36N2O6Sn
C29H24N2O6Sn
C29H42N2O6Sn
C24H24N4O12Sn
C30H36N4O12Sn
C34H28N4O12Sn
C37H35N4O12Sn
C26H24N4O12Sn
C38H52N4O12Sn
C24H26N4O6Sn
C26H26N4O6Sn
49.6 (49.5)
39.2 (40.2)
43.0 (42.9)
49.6 (49.7)
56.6 (55.3)
55.0 (54.2)
42.4 (38.0)
47.2 (47.0)
50.8 (50.3)
52.5 (52.5)
44.4 (43.8)
52.1 (51.3)
49.3 (49.0)
51.3 (52.7)
3.8 (3.6)
4.2 (4.2)
5.5 (5.5)
6.9 (6.9)
3.9 (4.0)
6.7 (6.5)
3.7 (3.9)
4.6 (4.2)
3.5 (3.4)
4.2 (3.8)
3.4 (3.9)
6.0 (6.1)
4.5 (4.2)
4.3 (4.3)
10.5 (10.4)
6.5 (6.6)
5.9 (5.8)
5.1 (5.0)
4.6 (3.8)
4.4 (4.8)
8.2 (7.6)
7.3 (7.3)
7.0 (7.8)
6.6 (6.2)
8.0 (8.4)
6.4 (6.2)
9.6 (9.3)
9.2 (9.3)
HL
1
2
3
80-82
4
105-107
103-105
90-92
5
6
7
Paste type
Paste type
92-94
8
9
10
11
12
13
114-116
139-141
Paste type
* See Schme 1 for compounds numbering
9

ACCEPTED MANUSCRIPT
3.1. Solid state FT-IR spectroscopy
Table 2 shows FT-IR data for peaks of our interest such as νOH, νNH, νC=C, νCO, νSn-C, νSn–
O and νSn–N. Precious information about synthesis and structural elucidation of the compounds
in the solid state can be obtained from the FT-IR data. The disappearance of νOH of the free
ligand after treatment with NaHCO3 in the spectrum of the sodium salt confirms the successful
formation of NaL. NaL was then used for complexation and coordinates to Sn atom through O
atom of the COO group that was confirmed by the presence of new peak for Sn-O in the region
of 463-422 cm-1 in the spectra of the complexes. This Sn-O peak was absent in the spectrum of
the sodium salt of the ligand (NaL). Similarly another important absorption in the region of 551-
515 cm-1 for C-Sn stretching vibration was observed in the spectra of the complexes. For C6H5-
Sn derivatives the C-Sn stretching peak was appeared at 282-274 cm-1 [22].
Strong absorption bands were observed for symmetric and asymmetric vibrations of the
carboxylate moiety in the range of 1380-1340 cm-1 and 1532-1501 cm-1, respectively in the
spectra of complexes while for the free ligand they appeared at 1317 cm-1 and 1539 cm-1. After
complexation the value of the symmetric vibration of the carboxylate moiety increases while that
of the asymmetric decreases resulting in decrease in difference of the wave number of the
asymmetric and symmetric vibrations of the carboxylate moiety ‘Δν’ [31]. In the spectrum of the
NaL the value of Δν is 265 cm-1 (Table 2) while that of the complexes is smaller than that of the
NaL. The magnitude of the Δν for the reported complexes is less than 200 cm-1 which reflects
either chelating or bidentate nature of the ligand. The value of Δν was also calculated from single
crystal XRD data by using the following equation [32, 33]:
The difference between the two C-O bond lengths (Å) is represented by δr and the O-C-O angle
(°) is represented by θOCO. After matching the values of Δν obtained both from FT-IR data
and crystal data it was found that both the values were in close agreement, i.e., FT-IR data for
HL and complexes 1 and 2 (222, 160, 153) and single crystal XRD data (224, 133, 136).
10

ACCEPTED MANUSCRIPT
Table 2: Selective FT-IR peaks (cm-1) for synthesized compounds*
Comp. #
ν Sn-N
ν Sn-C
-
ν Sn-O
-
ν NH
3269
3357
3348
3349
3361
3343
3370
3370
3372
3371
3367
3371
3373
3349
3353
ν C=O ν (COO) asym ν (COO) sym Δν
ν OH
-
1707
1705
1694
1698
1695
1697
1692
1700
1714
1713
1712
1713
1713
1694
1698
1539
1575
1507
1504
1509
1506
1532
1501
1514
1512
1510
1513
1510
1509
1506
1317
1310
1347
1351
1342
1351
1342
1370
1378
1380
1375
1381
1377
1347
1340
222 3111
HL
NaL
1
-
-
-
265
160
153
167
155
190
131
136
132
135
132
133
162
166
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
545
515
538
282
540
542
527
274
543
545
544
546
551
436
428
459
449
422
440
434
444
463
458
457
438
440
-
2
-
3
-
4
-
5
-
6
-
7
-
-
8
9
-
10
11
12
13
-
560
557
* See Schme 1 for compounds numbering
3.3. NMR results
1
3.3.1. H NMR
1
1
Table 3 presents the data of H NMR recorded in DMSO. The H NMR spectrum of the ligand
shows a peak for the carboxylate OH proton at 13.12 ppm. After complexation this peak was
absent in the spectra of the complexes. A cis conformation for the H-2 and H-3 protons was
3
confirmed by giving clear doublets with J = 12.0-12.4 Hz. H-6 and H-7 protons give doublet
while H-9 protons exhibit doublet of doublet. The complextion was further confirmed by the
appearance of new Sn-C peak in the spectra of the complexes.
A sharp singlet with clear seattleite peaks at 0.35 ppm was observed for Sn-CH3 protons in
2
complex 1. A value of 69 Hz was calculated for J[119Sn-1H] which corresponds to the penta-
coordinated environment of Sn in solution state [22]. In complex 2 two peaks were observed for
the Sn-CH2-CH3 protons. A quartet for CH2 protons (Hα) having 2J[119/117Sn-1H] = 76, 64 Hz was
observed while for CH3 protons (Hβ) a triplet was observed. For Sn-CH2-CH2-CH2-CH3 protons
11

ACCEPTED MANUSCRIPT
(complex 3 & 7) exhibited a total 4 peaks, i.e., two triplets (Hα & Hδ) and two multiplets (Hβ &
Hγ). The Sn-C6H5 protons of complex 4 and 8 exhibited total four peaks, i.e., one doublet and
two triplets in their respective regions for Hβ, Hγ and Hδ, respectively. The Sn-C6H11 protons of
complex 5 exhibited total three peaks, i.e., triplet (Hα), multiplet (Hβ) and broad signals (Hγ &
Hδ) in their respective regions. A sharp singlet with clear seattleite peaks at 0.80 ppm was
observed for Sn-CH3 protons in dimethyltin complex (6). A value of 100 Hz was calculated for
2J[119Sn-1H] which corresponds to the hexa-coordinated environment of Sn in solution state [22,
34]. A singlet peak at 2.04 ppm was observed for the CH2 protons of the Sn-CH2-C6H5 in
complex 9. A doublet of a doublet was observed in complex 10 for the CH proton of Sn-
3
3
CH=CH2 while for the CH2 protons two doublets with Jcis (6.0 Hz) Jtrans (9.6 Hz) were
observed. A very difficult and complicated type spectra was observed for the (-CH2)7 protons of
Sn-C8H17 in complex 11. However a little bit clear triplet was observed for the CH3 protons.
Lockhart’s equation [35] was used for the calculation of C-Sn-C bond angle for the value of
2J[119Sn-1H] in complex 1, 2 and 6 and are shown in Table 5. The observed values of C-Sn-C
bond angle in complex 1 and 2 (triorganotin derivatives) show penta-coordinated environment
while in complex 6 (diorganotin derivatives) hexa-coordinated environment [36]. Figure 1a
presents the spectrum of 1H NMR for complex 1.
3. 3.2. 13C NMR results
Table 4 presents the complete data for 13C NMR of the synthesized compounds. A downfield
shift was observed for the resonances of the carboxylate moiety due to the withdrawal of electron
density from ligand by electropositive Sn atom [37]. With respect to free ligand a minor change
was observed for the phenyl carbons signals. The position of signal for the Cα in phenyltin
complexes (4 & 8) falls in the range of 143.5-143.7 ppm which is specified for penta or hexa
coordinated environment [22]. The value of C-Sn-C bond angle for methyl and ethyl tin
1
complexes (1, 2, 6, 12 & 13) was measured by substituting the value of J[119Sn-13C] in the
Lockhart’s equation [38]. Howard's equations were for the calculation of C-Sn-C bond angles
for butyl and phenyl tin complexes (3, 4, 7 & 8) [39] and are given in Table 5. The C-Sn-C bond
angles calculated from NMR are in good agreement with those obtained from the X-
2
crystallography. For example, for complex 1 the C-Sn-C value obtained from the J(119Sn-1H)
12

ACCEPTED MANUSCRIPT
coupling using the Lockhart’s equation is 117° while that obtained from crystal data is 118°,
respectively. The representative 13C NMR spectrum of the complex 1 is shown in Fig. 1b.
3.3.3. 119Sn NMR results
Table 4 also presents the 119Sn NMR data and all the complexes (1-13) have shown a single peak
in their Sn NMR spectra that shows the presence of one specie in solution. For Me3Sn, Et3Sn,
Bu3Sn complexes the value of tin NMR was shifted towards highly shielded region (-6.23 to -
18.3 ppm) which may be due to the extensive electron donating ability of alkyl groups attached
to tin atom [40, 41]. For complex 4, Ph3SnL, the 119Sn signal appears at -258.3 ppm. The 119Sn
NMR of diorganotin(IV) derivatives lies in the range from -247 ppm to -271.1 ppm which shows
hexa-coordinated environment about Sn atom. The 119Sn NMR spectrum of the complex 1 is
shown in Fig. 1b.
Fig. 1a: 1H NMR spectrum of complex 1
13

ACCEPTED MANUSCRIPT
Fig. 1b: 13C and 119Sn NMR spectra of complex 1
14

ACCEPTED MANUSCRIPT
Table 3: 1H NMR data (ppm) for synthesized compounds*
Comp.
#
Proton No.
H9
OH
H2
H3
NH
H6
H7
H11
α
Β
Γ
δ
ε
12.0, 6.32, d
6.43, d 10.4, s
(12)
6.17, d 10.93,
7.30, d
(8.8)
7.58, d
(8.8)
7.62, d
(9.2)
7.66, d
(8.8)
7.50, d
(8)
7.72, d
(9.2)
7.72, d
(8.8)
7.52, d
(8.8)
7.51, d
(9.2)
7.53, d
(8.4)
7.51, dd
(3.6)
7.30, dd
(2.8)
7.30, dd
(2.8)
7.27, dd
(2.8)
7.24, dd
(3.2)
7.29, dd
(3.2)
7.29, dd
(2)
7.11, dd
(2.8)
7.10, dd
(2.8)
7.32, dd
(2.8)
7.45, d 3.80, s
(3.6)
7.45, d 3.82, s 0.35, s [69]
(2.8)
7.45, d 3.80, s 1.0, q [76,
(2.8)
7.46, d 3.81, s 1.03, t (8.0)
(2.8)
7.45, d 3.80, s
(3.2)
7.47, d 3.78, s 1.16, t (8.8) 1.80, m
(3.2)
7.47, d 3.79, s
(2)
7.45, d 3.78, s
(2.8)
7.45, d 3.82, s
(2.8)
7.45, d 3.78, s
(2.8)
7.45, d 3.80, s
-
-
-
-
-
HL
s
-
(12)
6.06, d
(12.4)
6.12, d
(12.4)
6.07, d
(12.4)
6.01, d
(12.0)
6.13, d
(12.4)
6.13, d
(12.4)
6.03, d
(12.4)
6.15, d
(12.0)
6.15, d
(12.4)
6.15, d
(12.4)
-
-
-
-
-
-
-
-
-
-
-
-
-
1
(12.4)
6.21, d 11.04,
(12.4)
6.19, d 10.71,
(12.4)
6.35, d 10.69,
(12.0)
6.24, d 10.47,
(12.4)
6.25, d 11.41,
(12.4)
6.25, d 10.71,
(12.4)
6.23, d 10.14,
(12.0)
s
-
-
-
-
-
-
-
-
1.14, t
(8.0)
1.51, q
2
s
64]
1.23,
m
7.10, 7.53, m
0.80, t
(7.2)
3
s
-
7.61, d
(6.4)
4
s
m
1.61, 1.61, m
m
-
5
s
0.80, s
[100]
0.97, t
(7.6)
-
-
-
6
s
1.50, m
1.30,
m
7.22, 7.66, m
0.81, t
(7.6)
7
s
6.97, d
(9.2)
-
8
s
m
6.28, d 9.98, s
(12.4)
6.32, d 10.41,
2.04, s
7.59, 7.89, m 7.14,
d (7.6)
-
9
m
-
7.51, d
(9.2)
7.13, dd
(2.4)
6.97, d
(t,9.6),7.32,
d (c, 6)
7.24,dd
(3.2)
-
10
(12.4)
s
(2.4)
-
6.30, d
(12.0)
6.37, d 10.55,
(12.0)
7.51, d
(8)
7.28, dd
(3.2)
7.45, d 3.80, s 1.14, t (7.2) 1.55 (bs)
(3.2)
1.38
(bs)
-
11
s
0.80, t
(7.2)
-
-
6.05, d
(12.4)
6.06, d
(12.4)
6.17, d 10.99,
(12.4)
6.19, d 11.20,
(12.4)
7.57, d
(8.8)
7.55, d
(9.2)
7.30, dd
(2.8)
7.32, dd
(2.8)
7.44, d 3.79, s 0.35, s [69]
(2.8)
7.43, d 3.78, s 0.37, s [70]
(2.8)
8.36 {d, 1H (7.6)}, 7.93 (m, 2H),
8.65 {d, 1H, (5.6)} (2,2'-Bipy H)
9.07 {d, 1H (3.2)}, 7.76 {t, 1H
(6.8)}, 8.48 {d, 1H (7.2)}, 7.96 {d,
1H (3.2)} (1,10-phen H)
12
13
s
s
* See Schme 1 for compounds numbering. nJ[119/117Sn-1H] in Hz
15

ACCEPTED MANUSCRIPT
Table 4: 13C NMR data (ppm) for synthesized compounds *
Carbon No.
C9 C10
Comp.
#
β
γ
δ
ε
119Sn
-
C1
C2
C3
C4
C5
C6
C7
C8
C11
α
163.8 131.0 131.6 167.4 123.8 128.0 120.7 157.1 109.7 144.2 56.6
-
-
-
-
-
HL
1
0.8
164.2 129.2 134.9 169.8 124.7 127.5 121.0 156.5 109.5 143.4 56.5
-
-
-
-
-
-
-
-
-
-8.9
-18.3
-6.23
-258.3
[516,512]
11.1 [491,
470]
10.6
[32]
28.2
[28]
164.2 130.3 134.1 170.3 124.8 127.3 121.0 156.5 109.5 143.2 56.5
2
3
4
26.9
[73]
164.1 130.5 134.3 170.0 125.0 127.2 120.9 156.4 109.5 142.9 56.5 20.2 [460]
14.2
142.9
136.4 128.5 129.
163.9 130.7 132.6 169.6 124.4 127.0 120.6 156.2 109.2 143.4 56.3
[682]
[46]
31.4
[22]
[70]
29.2
[73]
2
37.3 [432,
163.5 131.4 133.8 169.3 125.1 126.8 121.1 155.6 109.5 143.5 56.5
413]
27.1
-
-
-
-39.6
-189.4
-208.5
5
6
7
164.2 131.4 133.8 170.2 125.2 126.8 121.1 156.3 109.5 142.7 56.6 -0.7 [833]
-
-
-
28.0
[44]
26.1
[149]
163.9 129.6 135.9 169.8 124.6 127.6 121.3 156.6 109.4 142.5 56.0 31.2 [887]
14.2
142.2
164.8 131.5 133.4 170.7 123.5 127.3 121.0 156.8 109.4 143.8 56.3
[1517]
129.
3
135.6 128.5
-
-247
8
9
12
143.0
135.1
[189]
128.
6
163.6 132.9 135.9 169.8 125.0 127.7 121.3 156.8 109.6 142.5 56.5
19.9
6. -244.9
9
149.7
[616]
25.0
167.4 131.6 132.8 170.6 123.7 127.7 121.3 156.7 109.7 142.5 56.0
163.9 132.9 135.9 169.8 124.2 127.7 121.3 156.8 109.5 142.5 56.5
164.2 129.2 135.0 169.8 124.7 127.5 121.0 156.5 109.5 143.4 56.5
129.5
-
-
-271.1
-243.9
10
11
12
22.6
31.8
33.3 29.1
22.8 14.5
29.2
0.8 [527, 149.8,124.6,137.9,120.9,15
504]
-9.6
5.7 (2,2-bipy C)
150.5,123.9,136.9,129.0,14
5.9,127.2
164.2 129.9 135.2 169.8 124.7 127.5 120.9 156.5 109.5 143.5 56.5
1.3 [517]
-11.1
13
(l-1,10-phen C)
* See Schme 1 for compounds numbering. nJ[119/117Sn-13C] in Hz
16

ACCEPTED MANUSCRIPT
3.4. X-Ray Crystallography
3.4.1. HL
Figure 2 describes the molecular structure with atom number while Figure 3 describes the 3D-
packing diagram with unit cell. Table 6 describes the detailed crystal data while Tables 7 and 8
describe the selected bond lengths and bond angles, respectively. The molecule, (E)-4-((4-
methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid, crystallizes in orthorhombic system with
space group Pna21. The main plan of the phenyl ring ‘C5-C10’ and that of maleic acid plan
formed by C4-C1/O1-O3 has a dihedral angle of 48.2(3)°. Similarly the plans of phenyl ring
and–NHCO ‘amide segment’ are inclined with an angle of 41.1(3)°. Anti conformation was
observed for the amide segment NH and carbonyl group. The intramolecular hydrogen bonding,
O1-H1···O3, of 2.529Å, results in the formation of 7-membered ring involving C1-C4, O3, H1
and O1 atoms. There are lot of weak intra- and inter-molecular H-bonding such as C3-H3···O2
(3.256Å), C7-H7···O3 (3.528Å), C9-H9···O6 (3.231Å) and C11-H11B···O6 (3.440Å) which are
responsible for the formation of flower like 3D packing diagram (Fig. 2b). Table 9 and Figure S1
of the supplementary data presents the detail of intra- and inter-molecular H-bonding present in
(E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid.
Complexes 1 and 2
Figures 4 and 6 describe the molecular structures with atom numbering of complex 1 and 2,
respectively. Table 5 describes the detailed crystal data while Tables 6 and 7 describe the
selected bond lengths and bond angles, respectively. Both the molecules crystallize in
monoclinic system with space group of P21/c. A polymeric chain like structures is exhibited by
complex 1 and 2 which is formed by ligand, (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-
2-enoic acid. The geometry of complex can be measured form the values of τ (τ = (β-α)/60. Here
α is the axial angle and β is the largest basal angle around the tin atom. The values of τ complex
1 and 2 are 0.83 and 0.82, respectively which correspond that the tin atoms are situated in a
distorted trigonal bipyramidal geometry [42, 43]. The equatorial plane is made of three R groups
(R = CH3 in complex 1 and C2H4 in complex 2) while the apical positions are occupied by the
two oxygen atoms of two (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid
molecules. The O1-Sn-O2 bond angle is close to a linear arrangement, i.e., 175.69(7)° in
complex 1 and 173.50(6)° in complex 2. The sum of the angles subtended at tin atom in the
17

ACCEPTED MANUSCRIPT
equatorial position is close to 360°, i.e., 359.7° in complex 1 and 359.6° in complex 2. The Sn-O
bond lengths [Sn1-O1 = 2.323(2)Å & 2.347(1)Å and Sn1-O2 = 2.217(2)Å & 2.227(1)Å] are
between the covalent bond length (2.13Å) and van der Waals radii (3.69Å) showing the distorted
trigonal bipyramid environment of the tin atom [42, 43]. The value of Sn1-O2 (2.323 Å or 2.327
Å) is slightly greater than the value of normal Sn-O1 (2.054 Å). This may due be presence of
weak interaction between O2 and Sn atom making the 5-coordinated geometry. The asymmetric
Sn-O separations are also evident from difference in the bond lengths of C1-O1 = 1.265(4) Å,
1.251(2) Å and C1-O2 = 1.253(4) Å, 1.276(2) Å, respectively in complexes 1 and 2 [44]. Here
we have got a difference of only 0.012 Å and 0.025 Å, for the complex 1 and 2 which may be
due to the chelating nature of (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid,
and is responsible for the formation of the polymeric structure. Complex 1 exist in wavelike
packing diagram which is due the presence of various intra- and inter-molecular interactions
within and hydrogen bonding that also stabilize the polymeric chains in zigzag manner which are
linked into a three-dimensional network via C-H---π interactions. The polar imino hydrogen
atom of the amide derivative participates in intramolecular hydrogen bonds (N1-H1---O3). C-H--
-π, π→π and stacking interactions are responsible for the self-assembled structure of the
compounds. Extended networks of O-Sn-O, C-H--O and C-H---π contacts lead to aggregation
and a superamolecular assembly. Table 8 gives the detail of all possible intra-and inter-molecular
H-bonds.
Fig. 2: A perspective view of the (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-enoic acid
(HL) with atom number.
18

ACCEPTED MANUSCRIPT
Fig. 3: Packing digram with unit cell of (E)-4-((4-methoxy-2-nitrophenyl)amino)-4-oxobut-2-
enoic acid (HL).
19

ACCEPTED MANUSCRIPT
Fig. 4: A perspective view of the complex 1 with atom number.
Fig. 5: Packing digram with unit cell of complex 1 viewed along a-axis.
20

ACCEPTED MANUSCRIPT
Fig. 6: A perspective view of the complex 2 with atom number.
Fig. 7: Packing digram with unit cell of complex 2 viewed along b-axis.
21

ACCEPTED MANUSCRIPT
Table 5: Crystal data for HL and complexes 1-2
Parameters
Empirical formula
Formula weight
T (K)
HL
C11H10N2O6
266.21
Complex 1
Complex 2
C14H18N2O6Sn
428.99
C34H48N4O12Sn2
942.14
150(2)
150.15
150(2)
Crystal system
Space group
a (Å)
Orthorhombic
Pna21
Monoclinic
P21/c
Monoclinic
P21/c
23.681(4)
12.240(2)
3.7890(7)
90, 90, 90
1098.3(3)
4
16.440(2)
10.7009(13)
9.9748(12)
90, 104.528(2), 90
1698.7(4)
4
9.988(3)
b (Å)
28.795(7)
13.878(4)
90, 101.605(4), 90
3909.8(18)
4
c (Å)
α, β, γ (°)
V (Å3)
Z
ρcalc (mg/mm3)
M (mm-1)
1.610
1.677
1.601
0.134
1.534
1.341
F(000)
552.0
856.0
1904.0
Crystal size (mm3)
2θ range for data coll.
(°)
0.5 × 0.12 × 0.04
0.37 × 0.16 × 0.09
0.41 × 0.11 × 0.07
6.142 to 54.952
4.586 to 56.662
3.314 to 56.47
Radiation MoKα (λ)
Reflections collected
Independent
reflections
Data/restraints/param
eters
0.71073)
5476
0.71073
17007
0.71073
39266
1808 [Rint = 0.0324,
Rsigma = 0.0418]
4223 [Rint = 0.0544,
Rsigma = 0.0500]
9581 [Rint = 0.0552,
Rsigma = 0.0495]
1808/1/174
4223/0/211
0.960
9581/0/475
1.021
S on F2
1.052
R1 = 0.0360, wR2 =
0.0830
Final R indexes
[I>=2σ(I)]
R1 = 0.0368, wR2 =
0.0915
R1 = 0.0389, wR2 =
0.0810
CCDC#
997756
997757
997758
22

ACCEPTED MANUSCRIPT
Table 6: Selected bond lengths (Å) for HL and complexes 1-2
Bond lengths for HL
O1-C1
C1-C2
N1-C4
1.309(2)
1.497(2)
1.367(2)
O2-C1
C2-C3
N1-C9
1.226(2)
1.388(2)
1.406(2)
Bond lengths for complex 1
O1-Sn1
O2-Sn1
C1-C2
C1-O1
2.323(2)
2.217(2)
1.522(3)
1.265(4)
C12-Sn1
C13-Sn1
C14-Sn1
C1-O2
2.125(3)
2.125(3)
2.122(3)
1.253(4)
Bond lengths for complex 2
O1-Sn1
O2-Sn1
C1-C2
C1-O1
2.347(1)
2.227(1)
1.514(3)
1.251(2)
C12-Sn1
C14-Sn1
C16-Sn1
C1-O2
2.140(3)
2.138(3)
2.136(2)
1.276(2)
23

ACCEPTED MANUSCRIPT
Table 7: Selected bond angles (˚) for HL and complexes 1-2
Bond angles for HL
O1-C1-O2
O1-C1-C2
N1-C4-C3
120.6(2)
O2-C1-C2
C1-C2-C3
C4-N1-C5
118.5(3)
132.5(3)
122.6(2)
120.8(2)
114.2(2)
Bond angles for complex 1
O1-Sn1-C12
O1-Sn1-C13
O1-Sn1-C14
O1-Sn1-O2
O1-C1-O2
87.4(1)
86.9(1)
C12-Sn1-O2
C13-Sn1-O2
C14-Sn1-O2
C12-Sn1-C13
C12-Sn1-C14
C13-Sn1-C14
93.94(9)
88.9(1)
90.4(1)
92.08(9)
118.0(1)
126.0(1)
115.7(1)
175.69(7)
122.3(2)
120.8(2)
O1-C1-C2
Bond angles for complex 2
O1-Sn1-C12
O1-Sn1-C14
O1-Sn1-C16
O1-Sn1-O2
O1-C1-O2
87.71(8)
89.68(9)
86.01(8)
173.50(6)
122.6(2)
120.9(2)
C12-Sn1-O2
C14-Sn1-O2
C16-Sn1-O2
C12-Sn1-C14
C12-Sn1-C16
C14-Sn1-C16
94.34(9)
94.21(9)
87.64(8)
124.5(1)
120.6(1)
114.5(1)
O1-C1-C2
24

ACCEPTED MANUSCRIPT
Table 8: Hydrogen-bond angles and bond lengths for HL and complexes 1-2
D-H (Å)
H····A (Å)
D····A (Å)
D-H····A (˚)
D-H····A
HL
1.69
2.46
2.09
2.26
2.65
2.60
2.51
0.84
0.95
0.88
0.88
0.95
0.95
0.98
2.529(2)
3.256(4)
2.935(3)
2.723(3)
3.528(3)
3.231(3)
3.440(4)
173.9
140.9
161.3
113.0
154.5
124.1
158.0
O1-H1···O3
C3-H3···O21
N1-H1A···O21
N1-H1A···O5
C7-H7···O32
C9-H9···O63
C11-H11B···O63
Complex 1
2.055
2.372
Complex 2
2.53
N1-H1···O6
C6-H6···O3
0.880
0.950
122.72
113.32
2.637
2.883
C2-H2···O3Ai
N1-H1···O5
0.95
0.88
0.95
0.88
0.95
0.98
3.155(4)
2.624(5)
2.866(5)
2.624(4)
2.877(5)
3.294(5)
123.8
133.3
123.1
133.5
124.3
140.4
1.94
C6-H6···O3
2.23
N1A-H1A···O5A
C6A-H6A···O3A
C11A-H11DA···O6Aii
1.94
2.23
2.48
Symmetry transformations used to generate equivalent atoms for HL: 1)-1/2-X,-1/2+Y,-1/2+Z; 2) -X,1-Y,-1/2+Z; 3) -X,-Y,-1/2+Z
Symmetry transformations used to generate equivalent atoms for complex 2 (i) -1+X,1/2-Y,-1/2+Z; (ii) 4-X,-Y,1-Z
3.4. Mass Spectrometry
The MS data of the ligand and its complexes determined by ESI method is presented in Table 9.
Scheme 2 shows the detail fragmentation pattern of ligand, (E)-4-((4-methoxy-2-
nitrophenyl)amino)-4-oxobut-2-enoic acid (HL). Both [M]+ and [M+1]+ were appeared in the
MS of the HL with [M+1]+ as base peak at m/z = 269.
In the MS of the synthesized organotin carboxylates (1-13), the low intensity M+ (molecular ion
peaks) and [MNa]+ are observed in all spectra. Triorganotin compounds undergo fragmentation
by three pathways based on observed m/z in their spectra. In one pathway various fragments
25

ACCEPTED MANUSCRIPT
such as COOR' and R on elimination gave [Sn]+ as end product. The other two pathways after
primary elimination of [R]+ and [R3Sn]+ groups and then elimination of COO and successive R
(in one of the pathway) results in the formation of [R']+, which shows similar pattern for the
further elimination of different groups (Supplementary data; Scheme S1).
A bit different scheme of mass fragmentation pattern has been suggested for the diorganotin
compounds (Supplementary data; Scheme S2) but these pathways end up in similar manner as
suggested for the triorganotin compounds. In addition, the following ions: [C4H9]+, [C6H5]+,
[C7H7]+ and [C8H17]+ are also observed with reasonable intensities in the mass spectra of all
organotin(IV) derivatives.
26

ACCEPTED MANUSCRIPT
Scheme 2: General mass fragmentation pattern for HL
27

ACCEPTED MANUSCRIPT
Table 9: ESI-Mass fragmentation data with m/z value of the synthesized compounds*
Comp. No
HL
Fragment with m/z (%)
[C11H10N2O6Na]+ = 289 (90); [C11H10N2O6Na]+ = 291 (100); [C11H10N2O6]+ = 266 (10); [C11H11N2O6]+, {M+1}+ = 267
(95); [C11H11N2O6]+ = 269 (50); [C11H8O5N2]+ = 248 (23); [C10H8N2O4]+ = 220 (5); [C8H7N2O4]+ = 195 (30);
[C7H7N2O3]+ = 167 (10); [C7H7NO2]+ = 137 (5); [C7H6O]+ = 106 (11); [C7H6NO3]+ = 152 (12); [C6H4N2O2]+ = 136 (15);
[C6H3N2O2]+ = 135 (11)
[C14H18N2O6SnNa]+ = 453 (23); [C14H18N2O6Sn]+ = 430 (39); [C11H9O6N2]+ = 265 (13); [C10H9N2O4]+ = 221 (26);
[C3H9Sn]+ = 165 (100); [C2H6Sn]+ = 150 (6); [CH3Sn]+ = 135 (9); [Sn]+ = 120 (6); [C13H15N2O6Sn]+ = 415 (9);
[C12H15N2O4Sn]+ = 371 (9); [C11H12N2O4Sn]+ = 356 (1); [C10H9N2O4Sn]+ = 341 (9)
1
2
3
4
5
[C17H24N2O6SnNa]+ = 493 (5); [C17H24N2O6Sn]+ = 430 (8); [C11H9N2O6]+ = 265 (13); [C10H9N2O4]+ = 221 (86);
[C6H15Sn]+ = 207 (100); [C4H10Sn]+ = 178 (11); [C2H5Sn]+ = 149 (10); [Sn]+ = 120 (11); [C15H19N2O6Sn]+ = 443 (1);
[C14H19N2O4Sn]+ = 399 (1); [C12H14N2O4Sn]+ = 370 (2); [C12H14N2O4]+ = 250 (1)
[C23H36N2O6SnNa]+ = 579 (34); [C23H36N2O6Sn]+ = 556 (32); [C11H9N2O6]+ = 265 (12); [C10H9N2O4]+ = 221 (10);
[C12H27Sn]+ = 291 (100); [C8H18Sn]+ = 234 (11); [C4H9Sn]+ = 177 (9); [Sn]+ = 120 (7); [C19H27N2O6Sn]+ = 499 (29);
[C18H27N2O4Sn]+ = 455 (34); [C14H18N2O4Sn]+ = 398 (45); [C14H18N2O4Sn]+ = 341 (41)
[C29H24N2O6SnNa]+ = 639 (17); [C29H24N2O6Sn]+ = 616 (7); [C11H9N2O6]+ = 265 (2); [C10H9N2O4]+ = 221 (2);
[C18H15Sn]+ = 351 (100); [C12H10Sn]+ = 274 (17); [C4H9Sn]+ = 197 (23); [Sn]+ = 120 (1); [C23H19N2O6Sn]+ = 539 (15);
[C22H19N2O4Sn]+ = 495 (34); [C16H14N2O4Sn]+ = 418 (16); [C10H9N2O4Sn]+ = 341 (41)
[C29H42N2O6SnNa]+ = 657 (11); [C29H42N2O6Sn]+ = 634 (3); [C11H9N2O6]+ = 265 (25); [C10H9N2O4]+ = 221 (29);
[C18H33Sn]+ = 369 (100); [C12H22Sn]+ = 287 (30); [C6H11Sn]+ = 197 (7); [Sn]+ = 120 (12); [C23H31N2O6Sn]+ = 551 (28);
[C22H31N2O4Sn]+ = 507 (34); [C16H20N2O4Sn]+ = 424 (3); [C10H9N2O4Sn]+ = 341 (11)
28

ACCEPTED MANUSCRIPT
[C24H24N4O12SnNa]+, m/z = 703 (30); [C24H24N4O12Sn]+, m/z = 680 (11); [C23H21N4O12Sn]+, m/z = 665 (10);
[C12H12N2O6Sn]+ = 400 (9); [C11H9N2O6Sn]+ = 385 (3); [C11H9N2O6]+ = 265 (14); [C10H9N2O4]+ = 221 (29); [C2H6Sn]+ =
150 (14); [CH3Sn]+ = 135 (13); [Sn]+ = 120 (12); [C13H15N2O6Sn]+ = 415 (100); [C12H15N2O4Sn]+ = 371 (43);
[C11H12N2O4Sn]+ = 356 (35); [C10H9N2O4Sn]+ = 341 (15); [C22H21N4O10Sn]+ = 621 (2)
[C30H36N4O12SnNa]+ = 787 (11); [C30H36N4O12Sn]+ = 764 (2); [C26H27N4O12Sn]+ = 707 (3); [C15H18N2O6Sn]+ = 442 (6);
[C11H9N2O6Sn]+ = 385 (2); [C11H9N2O6]+ = 265 (7); [C10H9N2O4]+ = 221 (12); [C8H18Sn]+ = 234 (23); [C4H9Sn]+ = 177
(100); [Sn]+ = 120 (20); [C19H27N2O6Sn]+ = 499 (43); [C18H27N2O4Sn]+ = 455 (27); [C14H18N2O4Sn]+ = 398 (21);
[C10H9N2O4Sn]+ = 341 (21); [C25H27N4O10Sn]+ = 663 (2)
6
7
[C34H28N4O12SnNa]+ = 827 (10); [C34H28N4O12Sn]+ = 804 (5); [C28H23N4O12Sn]+ = 727 (33); [C17H14N2O6Sn]+ = 462
(23); [C11H9N2O6Sn]+ = 385 (31); [C11H9N2O6]+ = 265 (43); [C10H9N2O4]+ = 221 (46); [C12H10Sn]+ = 274 (20);
[C6H5Sn]+ = 197 (65); [Sn]+ = 120 (31); [C23H19N2O6Sn]+ = 539 (100); [C22H19N2O4Sn]+ = 495 (50); [C16H14N2O4Sn]+ =
418 (20); [C10H9N2O4Sn]+ = 341 (12); [C27H25N4O10Sn]+ = 685 (9)
8
[C37H35N4O12SnNa]+ = 870 (12); [C37H35N4O12Sn]+ = 847 (5); [C30H28N4O12Sn]+ = 756 (33); [C17H14N2O6Sn]+ = 491
(21); [C11H7N2O6Sn]+ = 400 (34); [C11H9N2O6]+ = 265 (33); [C10H9N2O4]+ = 221 (46); [C14H14Sn]+ = 302 (9); [C7H7Sn]+
= 211 (65); [Sn]+ = 120 (31); [C26H26N2O6Sn]+ = 582 (100); [C19H19N2O6Sn]+ = 491 (46); [C18H19N2O4Sn]+ = 447 (34);
[C11H12N2O4Sn]+ = 356 (21); [C29H28N4O10Sn]+ = 712 (12)
9
[C26H24N4O12SnNa]+ = 727 (23); [C26H24N4O12Sn]+ = 704 (10); [C24H21N4O12Sn]+ = 677 (4); [C13H12N2O6Sn]+ = 412 (3);
[C11H9N2O6Sn]+ = 385 (2); [C11H9N2O6]+ = 265 (2); [C10H9N2O4]+ = 221 (29); [C4H6Sn]+ = 174 (3); [C2H3Sn]+ = 147
(3); [Sn]+ = 120 (3); [C15H15N2O6Sn]+ = 439 (100); [C14H15N2O4Sn]+ = 395 (3); [C12H12N2O4Sn]+ = 368 (5);
[C10H9N2O4Sn]+ = 341 (25); [C23H21N4O10Sn]+ = 633 (5)
10
11
[C38H52N4O12SnNa]+ = 899 (43); [C38H52N4O12Sn]+ = 876 (60); [C30H35N4O12Sn]+ = 763 (6); [C19H24N2O6Sn]+ = 496
29