Bis-substituted diphenylamine arylidene hydrazones for the synthesis of new binuclear organotin(IV) complexes: Crystal structure, DNA cleavage and molecular docking

Article abstract of DOI:10.1016/j.poly.2018.08.040

Five dinuclear organotin(IV) complexes, R₄Sn₂L^a (R = Me, Ph) and R₄Sn₂L^b (R = Me, Ph and Bu) have been synthesized from reaction of R₂SnCl₂ with 2,4′- and 2,2′-bis-sub

Full text of DOI:10.1016/j.poly.2018.08.040

Accepted Manuscript
Bis-substituted diphenylamine arylidene hydrazones for the synthesis of new
binuclear organotin(IV) complexes: crystal structure, DNA cleavage and mo-
lecular docking
Maryam Yousefi, Tahereh Sedaghat, Jim Simpson, Hossein Motamedi,
Mohammad Reza Dayer
PII:
S0277-5387(18)30506-0
https://doi.org/10.1016/j.poly.2018.08.040
POLY 13363
DOI:
Reference:
Polyhedron
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Revised Date:
Accepted Date:
25 June 2018
27 July 2018
10 August 2018
Please cite this article as: M. Yousefi, T. Sedaghat, J. Simpson, H. Motamedi, M.R. Dayer, Bis-substituted
diphenylamine arylidene hydrazones for the synthesis of new binuclear organotin(IV) complexes: crystal structure,
DNA cleavage and molecular docking, Polyhedron (2018), doi: https://doi.org/10.1016/j.poly.2018.08.040
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Bis-substituted diphenylamine arylidene hydrazones for the synthesis of new binuclear
organotin(IV) complexes: crystal structure, DNA cleavage and molecular docking
Maryam Yousefia, Tahereh Sedaghata,*, Jim Simpsonb, Hossein Motamedi c,d, Mohammad Reza
Dayerc
a Department of Chemistry, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz,
Iran
b Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand
cDepartment of Biology, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran
dBiotechnology and Biological Science Research Center, Shahid Chamran University of Ahvaz,
Ahvaz, Iran
*corresponding author: tsedaghat@scu.ac.ir
1

Abstract
Five dinuclear organotin(IV) complexes, R4Sn2La (R = Me, Ph) and R4Sn2Lb (R = Me, Ph and
Bu) have been synthesized from reaction of R2SnCl2 with 2, 4- and 2, 2-bis-substituted
diphenylamine arylidene hydrazones, H4La and H4Lb, respectively. The synthesized compounds
have been investigated by elemental analysis and IR, 1H NMR, and 119Sn NMR spectroscopy.
The structures of Me4Sn2Lb and Ph4Sn2Lb have been also confirmed by X-ray crystallography.
The results show that the fully deprotonated bis-hydrazone ligand provides two contiguous ONO
tridentate domains that coordinate to the two SnR2 moieties in the enolate form. Each tin atom in
the complexes adopts a five-coordinate environment. Ligands and complexes showed no
antibacterial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and
Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. However, both ligands
and their methyl complexes were found to degrade DNA, an observation that adapt with the
mode of interaction suggested by molecular docking.
Keywords: organotin(IV); hydrazone; crystal structure; 119Sn NMR; DNA cleavage, molecular
docking
2

1.Introduction
Interest in the use of acyl-/aroyl-dihydrazones as polyfunctional ligands has increased
considerably [1-5]. Such ligands are derived from the condensation of acyl-/aroyl-dihydrazines
(organic acid dihydrazides) with aldehydes or ketones. The presence of two coordinating units
with several binding sites connected by bridges with different degrees of flexibility may produce
better coordinating properties in these ligands than for ligands with a single coordinating unit.
They are able to create different supramolecular architectures, coordination polymers and
polynuclear complexes involving ligand bridging [6-10]. Binuclear complexes of bis-hydrazones
may also be able to mimic the bimetallic sites found in several enzymes. To date the structure of
many transition metal complexes of multidentate dihydrazones have been studied extensively [1,
4, 11, 12]. However, a survey of literature reveals that the binuclear organotin(IV) complexes
with these types of ligands have been less widely studied. Research into the organotin chemistry
is a prolific area of chemical investigations. These compounds have found more industrial,
agricultural and medicinal applications than any other organometallic compounds [13-16]. In
addition, they present an interesting structural variety, so that structural studies have always been
prominent in organotin(IV) chemistry [13, 14, 17]. Among these investigations, hydrazone
organotin(IV) complexes have received much attention because of their potential
pharmacological applications and the possibility of chemical variations due to the presence of
different functional groups [18-23]. Because of this, the inclusion of two organotin units, instead
of just one, in the same molecular entity may produce new compounds with interesting
biological and structural properties. In this line, the first binuclear organotin(IV) complexes of
dihydrazones were synthesized in 1994 by Gopinathan and coworkers [24]. Then, in 2008, Yin et
al. reported dinuclear organotin(IV) complexes of bis-aroyl-hydrazones with a rigid spacer
3

between the hydrazine units [25]. Recently, the synthesis and structural investigation of binuclear
organotin complexes of bis-hydrazones have received attention again and we have also published
several articles in this area [26-34]. In most of these complexes, the dihydrazone ligand was
symmetric and both tin atoms were in the same chemical environments. This is readily proven by
observing only one signal in 119Sn NMR spectrum of the resulting complex. Recently we have
also reported binuclear organotin complexes of a multiprotic dihydrazone ligand containing both
ONS and ONN tridentate donor environments [33]. In a continuation of our research into
symmetric and asymmetric binuclear organotin complexes of bis-hydrazones, in this study we
have used diphenylamine as a linker for the synthesis of new types of dinuclear Sn(IV)
complexes with the N-aryl anthranilic acid ligands. It has been shown previously that
diphenylamine derivatives are anticancer and orally active antiproliferative agents that inhibit
tyrosine kinase autophosphorylation. Anti-inflammatory activity is also exhibited by a variety of
N-aryl anthranilic acid derivatives [35-37]. In view of the likely structural diversity and potential
anticancer activity of organotin(IV) complexes of such hydrazones, we report here the synthesis
of 2, 4- and the more symmetrical 2, 2-bis-substituted diphenylamine arylidene hydrazones,
Figure 1, and their use as binucleating ligands for the synthesis of a series of organotin(IV)
complexes.
2. Experimental
2.1. Materials and methods
All starting materials were obtained from commercial suppliers and used as received without
further purification. Copper powder used as catalyst for the synthesis of diphenylamine
carboxylic acids was activated by washing with a 1: l mixture of acetone and concentrated HCl
4

and then with aqueous acetone, and dried in a vacuum oven. 2, 4-diphenylamine dicarboxylic
acid (3a) was prepared according to a literature method with some modifications from the
reaction of 2-chlorobenzoic acid (1) and 4-aminobenzoic acid, 2a, in the presence of the copper
catalyst and excess potassium carbonate by refluxing for 18 h in DMF (m.p. 288 C) [38]. 2-[4-
(methoxycarbonyl)phenylamino] benzoic acid methyl ester (m.p. 75 C) (4a) and 2-[4-
(hydrazinecarbonyl)phenylamino] benzoic acid hydrazide (m.p. 245 C) (5a) were also prepared
by reported procedures with an increase in the reflux time [36].
The IR spectra were obtained using an FT BOMEM MB102 spectrophotometer. The 1H
and 119Sn NMR spectra were recorded with a Bruker Avance Ultrashield spectrometer using
TMS and SnMe4 respectively as internal references. Melting points were determined on a
Thermo Scientific LTD IA9200 apparatus. Elemental analyses were carried out on an Elementar
vario EL III analyzer.
2.2. Synthesis of H4La (6a)
2-[4-(Hydrazinecarbonyl)phenylamino]benzoic acid hydrazide (5a, 0.304 g, 1.2 mmol) and 2-
hydroxynaphthaldehyde (0.413 g, 2.4 mmol) were dissolved in ethanol (10 mL). Then two drops
of glacial acetic acid were added and the solution was refluxed for 6 h. The resulting green-
yellow precipitate was filtered and washed with ethanol. Yield: 0.611 g (86%); m.p. 298 °C
Anal. Calcd. for C36H27N5O4: C, 72.84; H, 4.58; N, 11.80 %. Found: C, 72.98; H, 4.73; N, 11.68
%. FT-IR (KBr, cm-1): (NH), 3366, 3219, (ArH), 3056; (C=O), 1640; (C=N), 1620. 1H
NMR (250 MHz, DMSO-d6): δ = 12.90, 12.70 (s, 2H, Hb,b), 12.27, 12.07 (s, 2H, Hc,c), 9.52 (s,
1H, NH), 9.46, 9.44 (s, 2H, Ha,a), 8.26-7.09 (m, 20H, Ar-H).
5

2.3. Synthesis of [Me4Sn2La] (7a)
To a stirred solution of H4La (0.148 g, 0.25 mmol) in ethanol (5 mL) triethylamine (1 mmol) was
added. This suspension was stirred for 10 min and then Me2SnCl2 (0.109 g, 0.5 mmol) in ethanol
(5 mL) was added. The suspension was refluxed for 4 h and during which time the yellow
precipitate changed to an orange solid product. This precipitate was collected, washed with
ethanol (5 mL) and dried in vacuum over CaCl2. Yield: 0.20 g (90%); m.p. 240 °C. Anal. Calcd.
for C40H35N5O4Sn2: C, 54.15; H, 3.98 N, 7.89 %. Found: C, 54.53; H, 3.82; N, 7.87 %. FT-IR
(KBr, cm-1): (C=N), 1616, 1601; as(SnC), 656; s(SnC), 562; (SnO), 523; (SnN), 464.
1H NMR (250 MHz, DMSO-d6): δ = 10.48 (s, 1H, NH), 9.70, 9.57 (s, 2H, Ha,a, 3J(119Sn-1H) =
32.4 Hz), 8.31-6.90 (m, 20H, Ar-H), 0.77, 0.74 [s, 12H, Me2Sn, 2J(119Sn-1H) = 88.3 Hz]. 119Sn
NMR (186 MHz, DMSO): δ = 208.2, 233.6.
2.4. Synthesis of [Ph4Sn2La] (8a)
Complex 8a was synthesized as described for 7a from H4La (0.148 g, 0.25 mmol), triethylamine
(0.13 mL, 1 mmol) and Ph2SnCl2 (0.172 g, 0.0.5 mmol). Yield: 0.22 g (78%); m.p. 272 °C; Anal.
Calcd. for C60H43N5O4Sn2: C, 63.47; H, 3.82; N, 6.17 %. Found: C, 63.76; H, 4.23; N, 6.21 %.
FT-IR (KBr, cm-1): (C=N), 1616, 1600; (SnO), 505; (SnN), 440. 1H NMR (250 MHz,
DMSO-d6): δ = 10.55 (s, 1H, NH), 9.75, 9.58 (s, 2H, Ha,a, 3J(119Sn-1H) = 29.8 Hz), 8.387.00
(m, 40H, Ar-H), 119Sn NMR (186 MHz, DMSO): δ = 399.6, 420.4.
2.5. Synthesis of 2, 2-diphenylamine dicarboxylic acid (3b)
This compound was synthesized by a procedure similar to that used for 3a. A solution of 2-
chlorobenzoic acid (1, 5.16 g, 33 mmol) and potassium carbonate (15 g, 180 mmol) in DMF (40
6

mL) was stirred for 15 min. Then a mixture of 2-aminobenzoic acid (2b, 4.93 g, 36 mmol) and
copper powder (0.6 g) in DMF (40 mL) was added. This mixture was refluxed for 20 h, at 140-
145 C and under a stream of nitrogen gas. During this time the color of the mixture changed
from brown to pink. The mixture was cooled to 60 C, added to 200 mL of ice-water and stirred
for 15 min. This solution was decolorized using activated carbon (3 g) at 100 C with stirring for
10 min. The mixture was filtered and enough HCl (6 M) was added to the solution in an ice bath
until the formation of precipitation was completed. The yellow solid product was filtered,
washed with water and dried at 50 C in an oven. Yield: 6.62 g (78%); m.p. 293 °C; FT-IR (KBr,
cm-1): (NH), 3330 sh; (OH), 3000-2800 br; (C=O), 1667. 1H NMR (300 MHz, DMSO-d6):
δ = 13.01 (s, 2H, OH), 10.81(s, 1H, NH), 7.91-6.91 (m, 8H, Ar-H).
2.6. Synthesis of 2-[2-(methoxycarbonyl)phenylamino] benzoic acid methyl ester (4b)
This compound was synthesized by a similar procedure to that reported for the chloro-derivative
of this compound with some modifications [37]. To a stirred solution of 3b (6.20 g, 24.12 mmol)
in MeOH (124 mL) in an ice bath, thionyl chloride (6.1 mL) was added dropwise. This solution
was stirred for 20 min at room temperature and then refluxed for 12 h. The dark solution was
then concentrated to half volume and put aside. The resulting pale green crystals were collected
and dried. Yield: 6.4 g (98%); m.p. 92 °C; FT-IR (KBr, cm-1): (NH), 3309 sh; (CHaliphatic),
2985-2940; (C=O), 1700. 1H NMR (300 MHz, DMSO-d6): δ = 10.72(s, 1H, NH), 7.92-6.95 (m,
8H, Ar-H), 3.85 (s, 6H, CH3).
7

2.7. Synthesis of 2-[2-(hydrazinecarbonyl)phenylamino]benzoic acid hydrazide (5b)
Hydrazine hydrate (64 mL) was added to 4b (6.7 g, 23.6 mmol) and the solution was refluxed for
15 h. The resulting white solid was filtered and dried. Yield: 6.2 g (95%); m.p. 275 °C; FT-IR
(KBr, cm-1): (NH), 3360, 3278, 3172; (C=O), 1645. 1H NMR (300 MHz, DMSO-d6): δ =
10.22 (s, 1H, NH), 9.64 (s, 2H, NH), 7.48-6.84 (m, 8H, Ar-H), 4.44 (s, 4H, NH2).
2.8. Synthesis of H4Lb (6b)
A solution of 2-hydroxynaphthaldehyde (0.413 g, 2.4 mmol) and 5b (0.317 g, 1.2 mmol) in
EtOH (10 mL) was refluxed for 6 h. The green-yellow solid product was filtered and washed
with EtOH. Yield: 0.572 g (83%); m.p. 275 °C; Anal. Calcd. for C36H27N5O4: C, 72.84; H, 4.58;
N, 11.80 %. Found: C, 72.73; H, 4.43; N, 11.95%. FT-IR (KBr, cm-1): (NH), 3360, 3241,
(ArH), 3060; (C=O), 1638; (C=N), 1624. 1H NMR (300 MHz, DMSO-d6): δ = 12.73 (s, 2H,
OH), 12.20 (s, 2H, NH), 10.32 (s, 1H, NH), 9.42 (s, 2H, CH=N), 8.21-7.06 (m, 20H, Ar-H).
2.9. Synthesis of [Me4Sn2Lb] (7b)
Complex 7b was synthesized as described for 7a from H4Lb (0.148 g, 0.25 mmol), triethylamine
(1 mmol) and Me2SnCl2 (0.109 g, 0.5 mmol) after a 6 h reflux. Yellow block-like crystals
suitable for X-ray crystallography were obtained by slow evaporation of an ethanol/methanol
(2:1) solution. Yield: 0.22 g (99%); m.p. 250 °C; Anal. Calcd. for C40H35N5O4Sn2: C, 54.15; H,
3.98 N, 7.89 %. Found: C, 54.29; H, 3.91; N, 7.93 %. FT-IR (KBr, cm-1): (C=N), 1617, 1600;
as(SnC), 649; s(SnC), 562; (SnO), 533; (SnN), 462. 1H NMR (300 MHz, DMSO-d6): δ
= 11.34 (s, 1H, NH), 9.53 (s, 2H, CH=N, 3J(119Sn-1H) = 37.5 Hz), 8.04-6.76 (m, 20H, Ar-H),
0.75 [s, 12H, Me2Sn, 2J(119Sn-1H) = 88.5 Hz]. 119Sn NMR (111 MHz, DMSO): δ = 292.8
8

2.10 Synthesis of [Ph4Sn2Lb] (8b)
Complex 8b was synthesized as described for 8a from H4Lb (0.148 g, 0.25 mmol), triethylamine
(1 mmol) and Ph2SnCl2 (0.172 g, 0.5 mmol) after a 4 h reflux. Red plate-like crystals suitable for
X-ray crystallography were obtained by slow evaporation of an ethanol solution. Yield: 0.15 g
(53%); m.p. 225 °C; Anal. Calcd. for C60H43N5O4Sn2: C, 63.47; H, 3.82; N, 6.17 %. Found: C,
63.03; H, 4.06; N, 6.47 %. FT-IR (KBr, cm-1): (C=N), 1616, 1600; (SnO), 521; (SnN),
448. 1H NMR (250 MHz, DMSO-d6): δ = 11.24 (s, 1H, NH), 9.57 (s, 2H, CH=N, 3J(119Sn-1H) =
47.5 Hz), 8.276.49 (m, 40H, Ar-H), 119Sn NMR (111 MHz, DMSO): δ = 407.7.
2.11. Synthesis of [Bu4Sn2Lb] (9b)
A solution of H4La (0.148 g, 0.25 mmol) and triethylamine (1 mmol) in ethanol (15 mL) was
stirred for 10 min. Bu2SnCl2 (0.152 g, 0. 5 mmol) in ethanol (10 mL) was then added. The
orange solution was refluxed for 5 h. After this time, a yellow precipitate formed on adding
water to the solution. This precipitate was collected and dried in vacuum over CaCl2. Yield: 0.20
g (85%); m.p. 78 °C. Anal. Calcd. for C52H59N5O4Sn2: C, 59.17; H, 5.63; N, 6.64 %. Found: C,
58.97; H, 5.71; N, 6.67 %. FT-IR (KBr, cm-1): (CHaliphatic), 2957-2857; (C=N), 1601;
(SnO), 527; (SnN), 461. 1H NMR (300 MHz, DMSO-d6): δ = 10.94 (s, 1H, NH), 9.56 (s,
2H, CH=N, 3J(119Sn-1H) = 40.0 Hz), 7.96-6.82 (m, 20H, Ar-H), 1.51-1.26 (m, 16H, CH2CH2),
1.14-1.03 (m, 8H, CH2), 0.58 (t, 12H, CH3, 3JHH = 7.7 Hz). 119Sn NMR (111 MHz, DMSO): δ =
245.7.
9

2.12. X-ray structure determination
Yellow block like crystals of 7b and red plates of 8b were used for data collection. X-ray
measurements for both structures were carried out on an Agilent Duo diffractometer using MoK
radiation (λ = 0.71073 Å) with data collection, reduction and absorption corrections controlled
using CrysAlisPro [39] and data were collected at 100(2) K. Data were reduced and multi-scan
absorption corrections were applied using CrysAlisPro [39]. Both structure was solved by direct
methods using SHELXT [40] and refined using full-matrix least-squares procedures using
SHELXL-2014/7 [41] and TITAN2000 [42]. All non-hydrogen atoms were refined
anisotropically and all hydrogen atoms bound to carbon were placed in the calculated positions,
and their thermal parameters were refined isotropically with Ueq = 1.2—1.5 Ueq(C). The N—H
hydrogen atoms in both molecules were located in difference Fourier maps and their coordinates
were refined with Ueq = 1.2 Ueq(N).
Once all of the non-hydrogen atoms of complex 7b had been located and refined, several
additional high peaks remained in the difference Fourier map that appeared to represent a water
molecule and an additional solvent molecule. However assignment and subsequent refinement of
these atoms proved difficult with high and increasing displacement parameters suggesting
significant disorder in both solvates. However a suitable disorder model could not be found. The
contribution to the scattering from these disordered solvates, was therefore removed with the
SQUEEZE routine [43] within PLATON [44] and subsequent refinement saw significant
improvements to the residuals.
Residuals for 8b were poor with R1 = 0.0731, which was the best result achieved from
data collections on three separate samples. Despite this, the structure solved and refined without
difficulty and the relatively poor data is reflected in the uncertainties reported for this structure.
10

Molecular plots and packing diagrams were drawn using Mercury [45]. Additional metrical data
were calculated using PLATON and tabular material was produced using WINGX [46]. Details
of the X-ray measurements and crystal data for both complexes are given in Table 1.
2.13. Antibacterial tests and DNA cleavage assay
The antibacterial activity of ligands and complexes at four different concentrations including 2.5,
5, 10 and 20 mg/mL in DMSO were evaluated against Escherichia coli ATCC25299,
Pseudomonas aeruginosa ATCC9027, Bacillus subtilis ATCC6633 and Staphylococcus aureus
ATCC6538 using the Kirby-Bauer standard disc diffusion method [19, 47]. No inhibition zone
was found around the discs prepared from these compounds. Hence, none of the tested
compounds showed any antibacterial activity.
Drug-DNA interaction was studied simply and sensitively by measuring structural
alteration or degradation in circular DNA obtained from either Gram-positive bacteria of B.
subtilis and S. aureus or Gram-negative bacteria of E. coli and P. aeruginosa on agarose gel
electrophoresis. The more potent binding of compounds to DNA provide shorter DNA fragments
moving faster on the gel with no retained band in the starting point (loading wells). Accordingly
the bacterial DNA was extracted by boiling method [19, 48]. Then a solution of each compound
in DMSO (20 mg/mL) was prepared and 10 µL of this solution was mixed with 10 µL of
extracted DNA and incubated at 37 C for 2 h. A positive control was prepared by mixing 10 µL
of H2O2 with 10 µL of DNA and an untreated DNA was used as negative control. These samples
then electrophoresed at 100 V for 50 min in a 1% agarose gel containing DNA safe stain. The
treated gel was documented under UV irradiation using a UVI-Tec gel documentation system.
11

2.14. Docking experiments
A double stranded DNA of 12 base pair with AGTCAGTCAGTCAGTC sequence was
constructed using ArgusLab software version 4.0.1 (http://www.planaria-software.com/). This
structure then equilibrated and optimized at 37 C, pH 7 and 1atomsphere of pressure in Gromacs
version 4.6.5 using Amber03 force field. Steep descent algorithm was used for energy
minimization and total energy for the system lower than 200 kJ/mol was used as energy
minimization criterion. After removing all hetero atoms the optimized structure was used as
receptor for docking experiments in Hex version 6.3 (http://hex/loria.fr/). Docking experiments
were carried out based on shape and electrostatic mode and default parameters using 6a, 6b, 7b
and 8b with different DNA binding and degrading potency as compounds for docking.
3. Results and discussion
2, 4-Diphenylamine dicarboxylic acid (3a) and 2, 2-diphenylamine dicarboxylic acid (3b) were
prepared from the reaction of 2-chlorobenzoic acid (1) with 4-aminobenzoic acid (2a) and 2-
aminobenzoic acid (2b), respectively. Then 2-[4-(methoxycarbonyl)phenylamino] benzoic acid
methyl ester (4a) and 2-[2-(methoxycarbonyl)phenylamino] benzoic acid methyl ester (4b) were
obtained through esterification of the corresponding diphenylamine dicarboxylic acid, 3a and 3b.
Hydrazinolysis of the diesters 4a and 4b gives 2-[4-(hydrazinecarbonyl) phenylamino] benzoic
acid hydrazide (5a) and 2-[2-(hydrazinecarbonyl)phenylamino] benzoic acid hydrazide (5b),
respectively. Condensation of the dihydrazides 5a and 5b with 2-hydroxynaphthaldehyde
afforded the bis-hydrazones 6a (H4La) and 6b (H4Lb). Figure 2 shows these synthetic pathways.
Bis-aroylhydrazone ligands, H4La and H4Lb, are isomers with four ionizable protons, two
each from the phenol and the amide functions. These ligands each have six potential donor atoms
12

with two tridentate domains connected by diphenylamine as a linker. The flexibility and
tautomerism present in these hydrazones has the potential to allow the ligands or their complexes
to adopt different orientations and coordination modes.
Five new binuclear organotin(IV) complexes 7a, 7b, 8a, 8b and 9b were synthesized by
reaction of H4La or H4Lb with R2SnCl2 (R = Me, Ph and n-Bu) in the presence of triethylamine as
1
a base in a 1:2:4 ratio. The new complexes were characterized by elemental analysis and IR, H
and 119SnNMR spectroscopy. The stoichiometry of the complexes was confirmed by the
analytical data and integrations in the 1H NMR spectra. The structures of 7b and 8b have also
been also confirmed by X-ray crystallography.
3.1. X-ray structures
The structures of 7b and 8b were determined by single-crystal X-ray diffraction analysis. Both
complexes crystallized in the monoclinic space group C 2/c with eight molecules in a unit cell.
Figure 3 shows the molecular structures of 7b with the structure of 8b shown in Figure 4.
Selected bond lengths and angles are listed in Tables 2 and 3. The structures of both complexes
reveal that complexation was preceded by ketone to enol tautomerism accompanied by complete
deprotonation of the ligand, Figure 5. The fully deprotonated aroyldihydrazone ligands provide
two contiguous ONO tridentate domains each of which coordinate the Sn atoms of two
organotin(IV) moieties forming the binuclear complexes. Structural parameters are very similar
for the two parts of the complex molecules. This is perhaps to be expected given the
symmetrical nature of the [Lb]4- ligand. Each tin center coordinates to the imine nitrogen,
phenolic oxygen and enolate oxygen atoms of the [Lb]4- ligands. The two C atoms of the methyl
and phenyl substituents of the organotin units increase the coordination numbers of the tin atoms
13

to five in each case with 5 and 6 membered chelate rings resulting from the coordination of the
O2 and N1 or the N1 and O1 atoms respectively. The trigonality index, τ = (α  )/60, was
calculated to determine the extent of structural distortion from ideal square pyramidal or trigonal
bipyramidal geometries around each tin atom. In this equation, proposed by Reedijk and
coworkers [49], α and β are the two largest bond angles around the metal atom in a five-
coordinate environment. The τ value for an ideal square pyramidal geometry is zero, while for
ideal trigonal bipyramidal geometry it would be unity. In the complex 7b, the τ value is 0.48 and
0.42 for Sn1 and Sn2 atoms, respectively; therefore both Sn atoms are located in highly distorted
square pyramid environment with the imine nitrogen (N1) in the axial position. The imine
nitrogen is chosen as axial because none of four donor atoms that make α and  should be placed
in apical position. The trigonality index for the Sn1 and Sn2 atoms in complex 8b are found to be
0.50 and 0.56. This indicates that the coordination geometry around Sn1 in 8b appears as
midway between square-pyramidal and trigonal-bipyramidal. For Sn2, the structure around the
metal tends more towards highly distorted trigonal-bipyramidal with the two oxygen atoms are in
the axial positions. The rigidity of chelate rings and the large covalent radius of tin(IV) leads to
these structural distortions from the ideal geometries [50, 51].
The Sn−N and Sn−O bond distances are considerably shorter than sum of van der Waals
radii of the corresponding atoms, 3.85 and 3.80 Ǻ, respectively, although they are very close to
the sum of the covalent radii of the elements (Sn−N, 2.15 Ǻ and Sn−O, 2.10 Ǻ) [52, 53].
Therefore, binding in this coordination complex is strong.
A search of the Cambridge Crystallographic Database (version 5.39; updated February
2018) [54] for five-coordinate tin complexes with a C2SnONO coordination sphere generated an
impressive 358 hits. However limiting this search to dimethyl and diphenyl derivatives with a
14

phenolateCH=NN=CO- coordination sphere resulted in 36 and 35 hits respectively. Of these
only 8 dimethyl and 5 diphenyl derivatives were found to be five coordinate binuclear complexes
with the two tin coordination spheres variously bridged alkyl chains [26, 27, 34] and in one
instance a benzene ring [25]. These contrast with the diphenylamine link observed here. In only
two instances were closely related diphenylmethane bridging systems observed [33].
3.2. Spectroscopic studies
In the spectra of complexes the absence of ν(C=O) and presence of two bands for the (C=N)
stretching mode, at a lower frequency than the ligand is evidence for the occurrence of a ketone
to enol tautomerism prior to coordination of the resulting enolic oxygen and the azomethine
nitrogen to tin. New bands were appeared in the ~400-600 cm-1 range that may be related to
(Sn-N) and (Sn-O) stretching modes. These further support coordination of the nitrogen and
oxygen to the diorganotin(IV) moieties [55-57].
Details of the 1H NMR spectral data of ligands and their complexes in DMSO are
presented in the experimental section. H4La is a 2,4-substituted diphenylamine and so the two
segments of the molecule provide slightly different chemical environments, therefore two signals
were observed for each of the Ar-OH, –NHN= and CH=N protons. In contrast, H4Lb is a
symmetrically 2,2-substituted diphenylamine with chemical equivalence for the equivalent set of
protons in solution. In the 1H NMR spectra of complexes, signals due to the four acidic OH
protons are absent, suggesting completely deprotonation of the ligand precedes coordination to
the tin centers in the enolate form. The ratio of the integrals of the methyl and phenyl resonances
15

of the organotin moieties to those of the ligands confirms the 2:1 ratio of metal to ligand in the
complexes.
In the 1H NMR spectra of 7a and 8a two resonances were observed for two imine protons
with both signals flanked by satellites due to 3J(119Sn-H) coupling. This confirms the
coordination of the two chemically different azomethine nitrogen atoms to the tin(IV) centers.
The 1HNMR spectrum of 7a also clearly shows two singlets for the resonances of the Me2Sn
protons confirming that the complex is binuclear with discrete environments for the chemically
different dimethyltin moieties. A singlet resonance attributable to the two imine protons appears
in the spectrum of the more symmetrical H4Lb. This is shifted slightly downfield and
accompanied by 119Sn satellites in the spectra of 7b and 8b confirming that the environments of
the coordinated tin(IV) centers are magnetically equivalent a fact further indicated by the
appearance of the 12 methyl protons of the SnMe2 groups of 7b as a singlet resonance . The
coupling constants, 2J(119Sn-1H), in of the methyl groups in the dimethyltin complexes, 7a (88.3
Hz) and 7b (88.5 Hz), are larger than those for Me2SnCl2 (68.7 Hz) due to the increased
coordination numbers of the tin centers. Substitution of this coupling constant into the Lockhart-
Manders equation [58], θ = 0.0162J2 1.322J + 133.4, gives values of 141.6° and 141.9° for the
CH3-Sn-CH3 angles of 7a and 7b, respectively, in DMSO solution. This value for 7b is different
from the value obtained from X-ray data in solid state. The discrepancy is doubtless due to
variations between the solid state and solution structures. The 2J(119Sn-1H) value for SnCH2 in
butyl complex cannot be extracted from the spectrum because of the complexity of the
methylene multiplets. All complexes show multiplets at 8.47.0 ppm for aromatic protons of
ligand. The phenyl protons of the Ph2Sn groups in 8a and 8b also appear in this range. These
signals cannot be carefully assigned due to significant overlap of the multiplets.
16

The 119SnNMR spectra of 7a and 8a show two sharp signals close together because of the
chemical environments of two tin centers in these complexes, while distinguishable, are only
slightly different. 119Sn resonances for two tin centers in 7a appear at 208.2 and 233.6 and at
399.6, 420.4 ppm for 8a. All these chemical shifts are at significantly lower frequencies in
comparison to the Me2SnCl2 (+137 ppm) and Ph2SnCl2 (-32 ppm) starting materials [16]. This is
again a result of the increase in the coordination number at the tin centers. Based on the
empirical chemical shift ranges observed for a variety of related organotin compounds, the
coordination number of the tin atoms in both complexes is five. The appearance of only one
sharp singlet in the 119Sn NMR spectra of 7b-9b indicates similar environments for two tin
centers in all of these complexes as expected. The values of these chemical shifts, 292.8,
407.7 and 245.7 ppm for 7b, 8b and 9b, respectively, are again indicative of a coordination
number of five for both tin centers in all of the complexes. It is generally found that the chemical
shifts for diphenyltin complexes appear at higher field due to anisotropic shielding effects and
possible π-interactions [28]. Signals are also found to appear at lower frequencies in coordinating
solvents such as DMSO [59].
3.3 Antibacterial activity and DNA cleavage
Based on antibacterial activity assessment in standard Kirby- Bauer disc diffusion method, none
of the tested ligands or their complexes were found to inhibit bacterial growth, i.e., no inhibition
zone was performed. These observations may be attributed to impermeability of bacterial cell
wall against these compounds and the probable absence of carrier system for active transport of
these large chemicals across cell wall and bilayer cytoplasmic membrane. On the other hand, this
finding reveals that there isn’t any target site for these compounds on bacterial cell wall. So,
17

these compounds can’t interact with any of enzymes involved in cell wall synthesis and growth,
carrier proteins, porins of outer membrane and enzymes of electron transport system [60-63].
As indicated in Figure 6, the ligands (6a and 6b) have completely changed DNA
structures for all strains used in this study and in comparison 6a behave more potently than 6b,
the character should rely on its more effective interaction. This Figure also shows that among
organotin complexes 7a and to lesser extent 7b, reveals low degrees of DNA structural
alterations with week bands retained in loading wells. The rest tin complexes of 8a, 8b and 9b
show no significant interaction with DNA due to unaffected bands in loading wells. To see what
happen in these experiments and to understand underling mechanism we turned to modeling and
docking experiment.
3.4 Molecular Modeling and Docking
DNA cleavage assays have shown that both free ligands of 6a and 6b and also tin complex of 7a
and 7b show activity in this context. In addition to 6a, 6b and 7b, we selected 8b as inactive
complex for docking experiments and comparison.
It is important to know that the ability of a compound to interact with DNA and perturb
its native structure has potential applications in cancer therapy. DNA binding compounds may
bind via their planar aromatic moiety and insertion between base pairs of DNA, the process
called intercalation and by this way they facilitate DNA degradation [64]. Double stranded DNA
in its three dimensional structure contain a wide and shallow binding pocket called major groove
which is suitable for binding of large molecules as regulatory protein and not small molecules as
our chemicals. There is another narrow and deep binding pocket which is more effective for drug
or chemical compound binding called minor groove [65, 66]. Therefore it seems logic that more
18

effective compounds in our experiment should bind to DNA through minor groove and the more
binding energy calculated for each compound should correlate with more degrading behavior.
As indicated in method section and in order to perform well designed docking
experiments we constructed a DNA molecule with 12bp with uniform distribution of nucleotide
to prevent sequence dependent binding energy for different compounds. This artificial DNA
should be converted to an equilibrated minimized structure at native like conditions of neutral
pH, 37 C, 0.1 M salinity and 1 atmosphere of pressure. The structure of compounds used in
these experiments including 6a, 6b, 7b and 8b were minimized in ArgusLAb and used for
docking. The total of 100 docking conformations or poses for each compound were saved and
analyzed for comparison. The binding energy of 100 poses for compounds were analyze in SPSS
and one way ANOVA and paired-sample T-test to compare their average. The average energies
obtained for 6a, 6b, 7b and 8b were calculated as -340.36±6.0, -305.26±5.8 -309.89±2.36 and -
274.37±2.6 kJ/mol, respectively (at p-value0.001 level). These energies are in agreement with
DNA cleavage potency sequence of 6a7b6b8b, the more potent binding compound cause the
more degrading ability. Graphical survey of the binding conformations for our compounds
(Figure 7) illustrates that among these compounds, 6a (Figure 7A) has more linear structure and
fits better to double stranded DNA and more importantly binds DNA through its minor groove.
This interprets more potent binding energy and more DNA cleavage ability of 6a in our
observations. Compound 6b (Figure 7B) due to its curved and globular structure (contrast to 6a)
could not bind to minor groove of DNA and obliged to interact via major groove. As indicated
earlier this contact is not efficient for binding, so the binding energy of 7b exceeds that’s of 6b.
Indeed 7b as shown in Figure 7C interact with DNA by inserting one of its bicyclic moieties
inside minor groove to stacks with DNA base pairs. Substitution of phenyl groups instead of
19

methyl groups in 7b leads to 8b complex. Figure 8 illustrates clearly that the four larger phenyl
groups by occupying surrounding space of 8b prevent bicyclic moieties of the molecule interact
with minor groove part of DNA and hence this compound arbitrary bind to DNA via major
groove with architecture not compatible with effective stacking with DNA base pairs (Figure
7D). Hence the mode of interaction suggested by molecular docking for our compounds seems to
adapt our experimental findings.
4. Conclusion
Both symmetric and unsymmetric bis-hydrazones used in this work are completely deprotonated
and coordinated to two diorganotin moiety through two ONO tridentate binding pocket.
Therefore dinulear organtin(IV) complexes with diphenylamine as linker were formed in which
coordination number of each tin will be five. Despite the lack of antibacterial activity of the
synthesized ligands and complexes, probably because of impermeability of bacterial cell walls,
DNA degradation and complimentary docking experiments reveal that ligands as well as
dimethyltin complexes show prominent DNA binding ability. These compounds that bind
through minor groove of DNA are appropriate to study for their anti cancer effects, taking in to
account that the impermeability of bacterial cell wall does not means that these compounds did
not pass human cell membranes, because cell membrane contain miscellaneous mechanisms for
transportation.
20

Acknowledgment
Support of this work by Shahid Chamran University of Ahvaz, Ahvaz, Iran (Grant No. 1396) is
gratefully acknowledged. We also thank the University of Otago for purchase of the
diffractometer and the Chemistry Department, University of Otago for support of the work of JS.
Appendix A. Supplementary material
CCDC 1824768 and 1824769 contains the supplementary crystallographic data for 7b and 8b,
respectively. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336 033; or e-mail:
deposit@ccdc.cam.ac.uk.
References
[1] A.-M. Stadler, J. Harrowfield, Inorg. Chim. Acta, 362 (2009) 4298-4314.
[2] D.P. Singh, R. Dwivedi, A.K. Singh, B. Koch, P. Singh, V.P. Singh, Sens. Actuators, B, 238
(2017) 128-137.
[3] I. Syiemlieh, A. Kumar, S.D. Kurbah, R.A. Lal, J. Mol. Struct., 1166 (2018) 252-261.
[4] L.D. Popov, A.N. Morozov, I.N. Shcherbakov, Y.P. Tupolova, V.V. Lukov, V.A. Kogan,
Russ. Chem. Rev., 78 (2009) 643-658.
[5] G.K. Patra, R. Chandra, A. Ghorai, K.K. Shrivas, Inorg. Chim. Acta, 462 (2017) 315-322.
[6] H. Adams, D.E. Fenton, G. Minardi, E. Mura, A.M. Pistuddi, C. Solinas, Inorg. Chem.
Commun., 3 (2000) 24-28.
[7] P. Zabierowski, M. Oszajca, M. Hodorowicz, D. Matoga, Polyhedron, 121 (2017) 25-32.
21

[8] T.S. Abedin, L.K. Thompson, D.O. Miller, E. Krupicka, Chem. Commun., (2003) 708-709.
[9] S.K. Dey, T.S. Abedin, L.N. Dawe, S.S. Tandon, J.L. Collins, L.K. Thompson, A.V.
Postnikov, M.S. Alam, P. Müller, Inorg. Chem., 46 (2007) 7767-7781.
[10] S. Naskar, D. Mishra, S.K. Chattopadhyay, M. Corbella, A.J. Blake, Dalton Trans., (2005)
2428-2435.
[11] K. Anđelković, M.R. Milenković, A. Pevec, I. Turel, I.Z. Matić, M. Vujčić, D. Sladić, D.
Radanović, G. Brađan, S. Belošević, B. Čobeljić, J. Inorg. Biochem., 174 (2017) 137-149.
[12] S.D. Kurbah, A. Kumar, I. Syiemlieh, M. Asthana, R.A. Lal, Inorg. Chem. Comm., 86
(2017) 39-43.
[13] M. Gielen, Tin chemistry: fundamentals, frontiers, and applications, John Wiley & Sons,
2008.
[14] A. Tarassoli, T. Sedaghat, in: R.P. Irwin (Ed.) Organometallic Chemistry Research
Perspectives, Nova Science Publishers, New York, 2007, pp. 221-248.
[15] M. Gielen, E.R. Tiekink, Metallotherapeutic drugs and metal-based diagnostic agents: the
use of metals in medicine, John Wiley & Sons, 2005.
[16] A.G. Davies, Organotin chemistry, John Wiley & Sons, 2006.
[17] P.J. Smith, Chemistry of tin, Springer Science & Business Media, 2012.
[18] K. Liu, H. Yan, G. Chang, Z. Li, M. Niu, M. Hong, Inorg. Chim. Acta, 464 (2017) 137-146.
[19] T. Sedaghat, Y. Ebrahimi, L. Carlucci, D.M. Proserpio, V. Nobakht, H. Motamedi, M.R.
Dayer, J. Organomet. Chem., 794 (2015) 223-230.
[20] S. Kumar, M. Nath, J. Organomet. Chem., 856 (2018) 87-99.
[21] C. González-García, A. Mata, F. Zani, M.A. Mendiola, E. López-Torres, J. Inorg. Biochem.,
163 (2016) 118-130.
22

[22] Y. Yang, M. Hong, L. Xu, J. Cui, G. Chang, D. Li, C.-z. Li, J. Organomet. Chem., 804
(2016) 48-58.
[23] Z. Ansari-Asl, T. Sedaghat, A. Tarassoli, H. Motamedi, E. Hoveizi, Phosphorus, Sulfur
Silicon Relat. Elem, 192 (2017) 538-543.
[24] M.P. Degaonkar, V.G. Puranik, S.S. Tavale, S. Gopinathan, C. Gopinathan, B. Chem. Soc.
Jpn, 67 (1994) 1797-1801.
[25] H.-d. Yin, J.-c. Cui, Y.-l. Qiao, Polyhedron, 27 (2008) 2157-2166.
[26] T. Sedaghat, M. Aminian, G. Bruno, H. Amiri Rudbari, J. Organomet. Chem., 737 (2013)
26-31.
[27] T. Sedaghat, M. Aminian, H. Amiri Rudbari, G. Bruno, J. Organomet. Chem., 754 (2014)
26-31.
[28] S. Shujah, N. Muhammad, A. Shah, S. Ali, A. Meetsma, Z. Hussain, J. Organomet. Chem.,
759 (2014) 19-26.
[29] D.K. Dey, S.P. Dey, N.K. Karan, A. Lyčka, G.M. Rosair, J. Organomet. Chem., 749 (2014)
320-326.
[30] T. Sedaghat, M. Aminian, M. Azarkish, Phosphorus, Sulfur, and Silicon and the Related
Elements, 190 (2015) 352-359.
[31] H. Zafarian, T. Sedaghat, H. Motamedi, H.A. Rudbari, J. Organomet. Chem., 825 (2016)
25-32.
[32] S. Kumar, M. Nath, J. Organomet. Chem., 853 (2017) 113-121.
[33] H. Zafarian, T. Sedaghat, H. Motamedi, D. Trzybiński, K. Woźniak, J. Organomet. Chem.,
853 (2017) 184-192.
23

[34] H. Ullah, B. Twamley, A. Waseem, M. Khawar Rauf, M.N. Tahir, J.A. Platts, R.J. Baker,
Cryst. Growth Des., 17 (2017) 4021-4027.
[35] T. Shimizu, Y. Fujiwara, T. Osawa, T. Sakai, K. Kubo, K. Kubo, T. Nishitoba, K. Kimura,
T. Senga, H. Murooka, Bioorg. Med. Chem. Lett., 14 (2004) 875-879.
[36] S.M. Abou-Seri, Eur. J. Med. Chem., 45 (2010) 4113-4121.
[37] A.A.H.M. Eissa, G.A.E.-H. Soliman, M.H. Khataibeh, Chem. Pharm. Bull., 60 (2012) 1290-
1300.
[38] I.B. Taraporewala, J.M. Kauffman, J. Pharm. Sci., 79 (1990) 173-178.
[39] P. CrysAlis, Agilent Technologies Ltd: Yarnton, 2013.
[40] G. Sheldrick, Acta Cryst. A, 71 (2015) 3-8.
[41] G. Sheldrick, Acta Cryst. C, 71 (2015) 3-8.
[42] K. Hunter, J. Simpson, TITAN2000: A molecular graphics program to aid structure solution
and refinement with the SHELX suite of programs, 1999.
[43] A. Spek, Acta Cryst. C, 71 (2015) 9-18.
[44] A. Spek, Acta Cryst. D, 65 (2009) 148-155.
[45] C.F. Macrae, I.J. Bruno, J.A. Chisholm, P.R. Edgington, P. McCabe, E. Pidcock, L.
Rodriguez-Monge, R. Taylor, J.v. Streek, P.A. Wood, J. Appl. Cryst., 41 (2008) 466-470.
[46] L.J. Farrugia, J. Appl. Cryst., 30 (1997) 565-565.
[47] J. Vandepitte, J. Verhaegen, K. Engbaek, P. Rohner, P. Piot, C. Heuck, Basic laboratory
procedures in clinical bacteriology, World Health Organization, 2003.
[48] J. Sambrook, E.F. Fritsch, T. Maniatis, Molecular cloning, Cold spring harbor laboratory
press New York, 1989.
24

[49] A.W. Addison, T.N. Rao, J. Reedijk, J. van Rijn, G.C. Verschoor, J. Chem. Soc., Dalton
Trans., (1984) 1349-1356.
[50] C. Pettinari, F. Marchetti, R. Pettinari, D. Martini, A. Drozdov, S. Troyanov, Inorg. Chim.
Acta, 325 (2001) 103-114.
[51] S. Öztaş, E. Şahin, N. Ancın, S. Ide, M. Tüzün, J. Mol. Struct., 705 (2004) 107-112.
[52] B. Cordero, V. Gómez, A.E. Platero-Prats, M. Revés, J. Echeverría, E. Cremades, F.
Barragán, S. Alvarez, Dalton Trans., (2008) 2832-2838.
[53] S. Batsanov, Inorg. Materials, 37 (2001) 871-885.
[54] C.R. Groom, I.J. Bruno, M.P. Lightfoot, S.C. Ward, Acta Cryst. B, 72 (2016) 171-179.
[55] T. Sedaghat, M. Naseh, G. Bruno, H. Amiri Rudbari, H. Motamedi, J. Mol. Struct., 1026
(2012) 44-50.
[56] B. Yearwood, S. Parkin, D.A. Atwood, Inorg. Chim. Acta, 333 (2002) 124-131.
[57] T. Sedaghat, M. Yousefi, G. Bruno, H. Amiri Rudbari, H. Motamedi, V. Nobakht,
Polyhedron, 79 (2014) 88-96.
[58] T.P. Lockhart, W.F. Manders, Inorg. Chem., 25 (1986) 892-895.
[59] L.S. Zamudio-Rivera, R. George-Tellez, G. López-Mendoza, A. Morales-Pacheco, E.
Flores, H. Höpfl, V. Barba, F.J. Fernández, N. Cabirol, H.I. Beltrán, Inorg. Chem., 44 (2005)
5370-5378.
[60] E. Padan, Encyclopedia of Life Sciences (ELS). John Wiley-Sons Ltd, Chichester, (2009).
[61] H. Bajaj, S. Acosta Gutierrez, I. Bodrenko, G. Malloci, M.A. Scorciapino, M. Winterhalter,
M. Ceccarelli, ACS nano, 11 (2017) 5465-5473.
[62] H. Nikaido, Mol. Microbiol., 6 (1992) 435-442.
25

[63] G.J. Mitchell, K. Wiesenfeld, D.C. Nelson, J.S. Weitz, J. Roy. Soc Interface, 10 (2013)
20120892.
[64] A. Mukherjee, W.D. Sasikala, Drug–DNA intercalation: from discovery to the molecular
mechanism, in: Advances in protein chemistry and structural biology, Elsevier, 2013, pp. 1-62.
[65] C.T. Winston, D.L. Boger, Chem. Biol., 11 (2004) 1607-1617.
[66] S. Neidle, Nat. Prod. Rep., 18 (2001) 291-309.
26

Table 1 Crystallographic and structure refinement data for 7b and 8b
8b
7b
C60H42N5O4Sn2
1134.36
100(2)
Empirical formula
Formula weight
T (K)
C40H33N5O4Sn2
885.09
100(2)
1.54184
Monoclinic
C 2/c
Wavelength, λ (Å)
Crystal system
Space group
Crystal size (mm3)
a (Å)
b (Å)
c (Å)
 (˚)
1.54184
Monoclinic
C 2/c
0.18  0.11  0.09
24.8269(4)
11.5856(3)
26.5907(4)
90
0.21  0.08  0.08
28.8935(19)
8.7165(5)
40.270(3)
90
106.740(7)
90
9712.2(11)
8
β (˚)
γ (˚)
V (Å3)
102.587(2)
90
7464.6(3)
8
Z
4552
F(000)
3520
Index ranges
-25≤ h ≤25
-11≤ k ≤ 8
-26≤ l ≤ 26
19011
-35≤ h ≤35
-10≤ k ≤10
-49≤ l ≤ 49
44706
Reflections collected
9650 [R(int) = 0.1078]
100 %
Independent reflections
Completeness to theta = 67.684 ˚
Absorption correction
Max. and min. transmission
Refinement method
3833
100 %
Multi-scan
1.0000 and 0.69429
Full-matrix least squares on F2
3833/0/467
0.882
1.0000 and 0.57769
9650 / 72 / 631
1.054
Data / restraints / parameters
2
Goodness-of-fit on F
R1 = 0.0731, wR2 =
0.1820
Final R indices [I>2sigma(I)]
R1 = 0.0211, wR2 = 0.0540
R1 = 0.0888, wR2 =
0.1935
R indices (all data)
Largest diff. peak and hole
R1 = 0.0225, wR2 = 0.0549
0.307 and -0.543
2.833 and -2.042 e.Å-3
27

Table 2. Bond lengths [Å] and angles [] for complex 7b
2.095(2)
2.132(2)
2.110(4)
2.106(4)
2.148(3)
1.306(5)
1.303(5)
1.403(4)
1.307(5)
1.316(5)
1.382(5)
2.097(3)
2.144(2)
2.103(4)
2.099(4)
2.141(4)
1.305(5)
1.305(5)
1.400(4)
1.299(5)
1.306(5)
1.381(5)
Sn1O1
Sn1O2
Sn1C19
Sn1C20
Sn1N1
C12O2
C11N1
N1N2
Sn2O1
Sn2O2
Sn2C19
Sn2C20
Sn2N1
C12O2
C11N1
N1N2
N2C12
C2O1
C14N3
N2C12
C2O1
C14N3
154.04(12)
94.70(13)
97.26(13)
93.04(13)
98.30(13)
81.69(11)
125.44(17)
73.66(11)
125.42(14)
108.96(14)
155.14(12)
97.41(16)
93.90(16)
95.33(15)
94.17(15)
81.26(12)
129.9(2)
73.94(12)
116.85(17)
113.07(15)
O1Sn1-O2
O1Sn2-O2
O1Sn2C19
O1Sn2C20
O2Sn2C19
O2Sn2C20
O1Sn2N1
C19Sn2C20
O2Sn2N1
N1Sn2C19
N1Sn2C20
O1Sn1C19
O1Sn1C20
O2Sn1C19
O2Sn1C20
O1Sn1N1
C19Sn1C20
O2Sn1N1
N1Sn1C19
N1Sn1C20
1.7(4)
8.6(5)
-2.1(5)
4.3(4)
-4.0(5)
-3.4(6)
-4.9(5)
-15.1(6)
4.4(6)
8.2(4)
-2.1(5)
8.5(6)
N2C12O2Sn1
C1C2O1Sn1
C1C11N1Sn1
Sn1N1N2C12
N1N2 C12O2
C2C1C11N1
N2C12O2Sn2
C1C2O1Sn2
C1C11N1Sn2
Sn2N1N2C12
N1N2 C12O2
C2C1C11N1
28

Table 3. Bond lengths [Å] and angles [] for complex 8b
2.084(6)
2.110(6)
2.121(7)
2.114(9)
2.140(6)
1.307(9)
1.300(10)
1.401(9)
1.315(10)
1.312(11)
1.402(10)
2.082(6)
2.126(5)
2.118(8)
2.118(9)
2.141(4)
1.313(9)
1.295(9)
1.394(8)
1.303(10)
1.299(9)
1.299(9)
Sn1O1
Sn1O2
Sn1C19
Sn1C25
Sn1N1
C12O2
C11N1
N1N2
Sn2O1
Sn2O2
Sn2C19
Sn2C25
Sn2N1
C12O2
C11N1
N1N2
N2C12
C2O1
C14N3
N2C12
C2O1
C14N3
155.5(2)
97.1(3)
93.3(3)
98.0(3)
94.2(3)
82.6(2)
123.5(3)
74.1(2)
110.8(3)
125.6(3)
155.2(2)
96.9(3)
95.2(3)
93.4(3)
98.5(3)
82.1(2)
121.5(3)
73.3(2)
121.6(3)
116.7(3)
O1Sn1-O2
O1Sn2-O2
O1Sn2C19
O1Sn2C25
O2Sn2C19
O2Sn2C25
O1Sn2N1
C19Sn2C25
O2Sn2N1
N1Sn2C19
N1Sn2C25
O1Sn1C19
O1Sn1C25
O2Sn1C19
O2Sn1C25
O1Sn1N1
C19Sn1C25
O2Sn1N1
N1Sn1C19
N1Sn1C25
-11.0(9)
-1.6(12)
13.1(12)
5.8(8)
3.5(10)
5.0(12)
-13.0(9)
-21.0(12)
11.3(11)
12.0(8)
0.8(10)
9.5(12)
N2C12O2Sn1
C1C2O1Sn1
C1C11N1Sn1
Sn1N1N2C12
N1N2 C12O2
C2C1C11N1
N2C12O2Sn2
C1C2O1Sn2
C1C11N1Sn2
Sn2N1N2C12
N1N2 C12O2
C2C1C11N1
29