Synthesis, spectroscopic characterization and DNA cleavage studies of dibutyltin(IV) complexes of bidentate Schiff bases

Article abstract of DOI:10.1016/j.ica.2013.10.012

Reactions of di-n-butyltin(IV)dichloride with sodium salts of Schiff bases in tetrahydrofuran-benzene solution in 1:1 and 1:2 stoichiometry afforded complexes of the types [(n-Bu)₂Sn(sb)Cl] and [(n-Bu) ₂Sn(sb)₂], respectiv

Full text of DOI:10.1016/j.ica.2013.10.012

Inorganica Chimica Acta 410 (2014) 39–45
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis, spectroscopic characterization and DNA cleavage studies
of dibutyltin(IV) complexes of bidentate Schiff bases
Raj Kumar Dubey a, , Avadhesh Pratap Singh , Sangamesh A. Patil b
⇑
a
a
Synthetic Inorg. and Metallo-organic Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad 211002, India
Department of Chemistry, Karnatak University, Dharwad 580003, India
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 23 May 2013
Received in revised form 10 October 2013
Accepted 11 October 2013
Available online 19 October 2013
Reactions of di-n-butyltin(IV)dichloride with sodium salts of Schiff bases in tetrahydrofuran-benzene
solution in 1:1 and 1:2 stoichiometry afforded complexes of the types [(n-Bu)
Sn(sb) ], respectively, [where sb = Schiff bases: N-salicylidene-2-aminopyridine (sapH), N-salicylidene-
-methylaniline (o-smabH) and N-salicylidene-4-methylaniline (p-smabH)]. All these complexes which
are colored solids and are soluble in common organic solvents were characterized by elemental (C, H,
2
Sn(sb)Cl] and [(n-Bu)2-
2
2
1
13
119
N, Cl and Sn) analysis and spectral [IR, ( H, C and
Sn) NMR] and Mass studies. On the basis of
Keywords:
Schiff bases
spectroscopic studies plausible structures have been proposed. The DNA cleavage activity of these
complexes has been studied by agarose gel electrophoresis method.
Ó 2013 Elsevier B.V. All rights reserved.
Organotin(IV) complexes
119
Sn NMR
DNA cleavage
1
. Introduction
Organotin(IV) compounds are of current interest due to their
(Merck), o-toludine (BDH), p-toludine (Merck) were used without
further purification. Benzene (AR Merck), tetrahydrofuran (AR
Merck), n-hexane (AR Merck) were dried by refluxing over so-
dium-benzophenone, followed by distillation under anhydrous
conditions. Other solvents were purified by standard procedures
[17]. Elemental analyses were performed with a Haraeus Carlo
Erba 1108 elemental analyzer. Tin was estimated gravimetrically
wide range of applications [1] such as homogeneous catalysts in
industry, biocides [2–4], antitumor [5,6], antibacterial, acaricidal,
and antifungal activities [7,8]. Furthermore, organotin(IV) com-
plexes derived from N-salicylidene amino acid have shown notable
antitumor activities in human tumor cell line [9]. The cleavage
3
as SnO2, after decomposition with concentrated HNO . Chlorine
[
10–12] of the DNA by Schiff base metal complexes derived from
was estimated volumetrically by using Volhard method. Infrared
spectra were recorded on a Perkin-Elmer 100 FT-IR spectrometer
the salicylaldehyde has also been reported. To our knowledge,
however, no example have been reported in the literature [1b] con-
cerning the synthesis, spectroscopy and DNA cleavage activity of
di-n-butyltin(IV) complexes based on bidentate Schiff bases of
the types used in this paper. As part of our investigations on Schiff
base metal complexes containing oxygen and nitrogen donor
atoms [13–16], we report herein synthesis, spectrochemical char-
acterization and DNA cleavage studies of di-n-butyltin(IV) com-
plexes derived from Schiff bases such as sapH, o-smabH, p-smabH.
À1
1
13
119
in the range 4000–400 cm . H, C and
recorded on Bruker DRX-300 spectrometer. Chemical shifts were
given in ppm relative to Me Si for carbon, hydrogen and Me Sn
for tin in CDCl /DMSO-d solvent. TOF-MS and ESI-MS spectra
Sn NMR spectra were
4
4
3
6
were recorded on WATERS TOF MS and Agilent 6520 Q-Tof LCMS,
MS/MS spectrometers respectively.
2.2. DNA cleavage experiment
2
. Experimental
Cleavage products were analyzed by agarose gel electrophoresis
method [18]. Test samples (1 mg/ml) were prepared in DMF. The
samples (25 g) were added to the isolated DNA of Escherichia coli
and Aspergillus niger. The samples were incubated for 2 h at 37 °C
and then 20 l of DNA sample was loaded carefully into the elec-
trophoresis chamber wells along with standard DNA marker con-
taining TAE buffer and finally loaded on agarose gel and passed
the constant 50 V of electricity for around 30 min. Removed the
2
.1. Materials and physical measurements
l
All chemicals and reagents were of reagent grade. Di-n-butyl-
l
tin(IV)dichloride (Fluka), Salicylaldehyde (Loba), 2-aminopyridine
⇑
Corresponding author.
E-mail address: rajalkoxy@yahoo.com (R.K. Dubey).
gel and stained with 10.0 lg/ml ethidium bromide for 10–15 min
0
020-1693/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2013.10.012

4
0
R.K. Dubey et al. / Inorganica Chimica Acta 410 (2014) 39–45
and the bands observed under Vilberlourmate Gel documentation
system and photographed to determine the extent of DNA cleav-
age. Then the, results are compared with standard DNA marker.
moved by distillation. The solid products were dried under reduced
pressure and recrystallized from a mixture of THF/n-hexane
(20:80) at À20 °C.
2
.3. Synthesis of Schiff bases
2.4.1. [(n-Bu)
Yield: 84%, brown solid, m.p. 83–85 °C. Anal. Calc. for C20
ClN OSn: C, 51.59; H, 5.84; N, 6.02; Cl, 7.61; Sn, 25.50. Found: C,
51.55; H, 5.82; N, 5.98; Cl, 7.52; Sn, 25.36%. H NMR (CDCl
ppm): 9.32(1H, s, CH@N), 8.40(d, 1H, Py–H), 6.30–7.89(m, 7H,
Ar, Py) 1.27–1.71(12H, m, Sn–(CH –), 0.89–0.83(6H, m, CH ).
) (ppm): 161.64 (s, CO), 161.09 (s, CN), 145.84,
136.84, 132.80, 129.95, 128.56, 120.95, 119.84, 118.93, 117.16,
2
Sn(sap)Cl](1)
H
27-
The Schiff base ligands were synthesized according to the pro-
2
1
cedure described in some of our earlier publications [15,16].
3
)
(
2.4. Synthesis of complexes
2
)
3
3
1
3
C NMR (CDCl
3
Similar procedure was used for the preparation of the com-
n
plexes (1–6), therefore, general preparative details are given be-
SnCl , sodium salt
116.60, (s, Ar–C
,
Py–C), 27.63, 20.99, 20.45, 13.56 (s, Sn–Bu ).
1
19
À1
low: To a benzene (ꢀ 20 ml) solution of n-Bu
2
2
Sn NMR (DMSO-d
6
) (ppm): À138.76. IR (KBr, cm ) 1617 (
m
C-
of Schiff base [prepared by the reaction of equimolar amounts of
sodium metal and a Schiff base (HL) in tetrahydrofuran (ꢀ30 ml)]
in appropriate (1:1 and 1:2) molar ratios was added dropwise with
constant stirring. The reaction mixture was refluxed for ꢀ5 h. The
precipitated NaCl was removed by filtration. The solvent was re-
@
N
), 681 ( Sn–C), 538 (mSn–O), 417 (mSn–N).
m
2.4.2. [(n-Bu)
Yield: 88%. dark brown solid, m.p. 136–137 °C. Anal. Calc. for
Sn: C, 61.26; H, 5.78; N, 8.93; Sn, 18.92. Found: C,
2 2
Sn(sap) ](2)
32 36 4 2
C H N O
Complex
W
X
Y
1
2
3
4
5
6
N
N
C
C
C
C
H
H
H
H
H
H
CH
CH
H
3
3
CH
3
3
H
CH
Scheme 1. General method for preparation of Schiff bases and di-n-butyltin(IV) complexes.

R.K. Dubey et al. / Inorganica Chimica Acta 410 (2014) 39–45
41
6
9
1
1.23; H, 5.72; N, 8.88; Sn, 18.86%. 1H NMR (CDCl
.36(2H, s, CH@N), 8.43(d, 2H, Py–H), 6.40–7.90(m, 14H, Ar, Py)
3
) (ppm):
1.28–1.79(12H, m, Sn–(CH
(CDCl
130.24, 129.94, 128.53, 122.92, 120.94, 119.83, 118.91, 117.15,
2
)
3
–), 0.90–0.84(6H, m, CH
3
). 13C NMR
3
) (ppm): 161.63 (s, CO), 161.59 (s, CN), 136.83, 132.80,
1
3
.30–1.59(12H, m, Sn–(CH
) (ppm): 163.92 (s, CO), 160.84 (s, CN), 156.95, 148.11,
46.94, 136.72, 132.64, 130.13, 121.83, 119.28, 118.51, 116.79 (s,
2 3 3
) –), 0.86–0.73(6H, m, CH ). C NMR
(
CDCl
3
116.56, (s, Ar–C), 20.98 (s, Ar–CH
3
), 27.25, 26.56, 26.41, 13.56 (s,
n
119
À1
1
Sn–Bu ).
1596 (
Sn NMR (DMSO-d
), 679 ( Sn–C), 528 (
6
) (ppm): À139.88. IR (KBr, cm
)
n
119
Ar–C, Py–C), 26.33, 26.43, 26.51, 12.76 (s, Sn–Bu ).
Sn NMR
Sn–
), 678 (m -
m
C
@
N
m
m
Sn–O), 423 (
mSn–N).
À1
(
DMSO-d
6
) (ppm): À309.94 IR (KBr, cm ) 1612 (
m
C
@
N
C
), 536, (mSn–O), 419 (mSn–N).
2
.4.4. [(n-Bu)
Yield: 85%, light yellow solid, m.p. 112–115 °C. Anal. Calc. for
Sn: C, 66.71; H, 6.48; N, 4.29; Sn, 18.17. Found: C,
2 2
Sn(o-smab) ](4)
2.4.3. [(n-Bu)
2
Sn(o-smab)Cl](3)
C
36 42 2 2
H N O
1
Yield: 86%, light yellow solid, m.p. 72–74 °C. Anal. Calc. for C22-
66.13; H, 6.42; N, 4.22; Sn, 18.17%. H NMR (CDCl
8.68(2H, s, CH@N), 6.67–7.31(m, 16H, Ar–H), 2.51(6H, s, Ar–CH
1.18–1.64(12H, m, Sn–(CH
(CDCl
3
) (ppm):
),
). C NMR
3
) (ppm): 164.60 (s, CO), 161.71 (s, CN), 138.28, 137.83,
H
30ClNOSn: C, 55.21; H, 6.32; N, 2.93; Cl, 7.41; Sn, 24.80. Found: C,
3
1
13
5
5.17; H, 6.28; N, 2.90; Cl, 7.38; Sn, 24.76%. H NMR (CDCl
3
) (ppm):
),
2 3 3
) –), 0.85–0.87(6H, m, CH
8
.54(1H, s, CH@N), 6.67–7.31(m, 8H, Ar–H), 2.31(3H, s, Ar–CH
3
2
Scheme 2. Fragmentation pattern of [(n-Bu) Sn(sap)Cl] (1) derived from TOF-MS spectrum.

4
2
R.K. Dubey et al. / Inorganica Chimica Acta 410 (2014) 39–45
1
1
33.69, 133.27, 130.81, 129.11, 126.23, 122.35, 120.07, 118.97,
2
2.4.5. [(n-Bu) Sn(p-smab)Cl](5)
17.05 (s, Ar–C), 25.57 (s, Ar–CH
3
), 27.28, 26.92, 26.24, 13.39 (s,
Yield: 81%, dark yellow solid, m.p. 78–80 °C. Anal. Calc. for C22-
n
119
À1
Sn–Bu ).
598 (
6
Sn NMR (DMSO-d ) (ppm): À387.67. IR (KBr, cm
), 634 ( Sn–C), 524 (
)
H30ClNOSn: C, 55.21; H, 6.32; N, 2.93; Cl, 7.41; Sn, 24.80. Found: C,
1
1
m
C
@
N
m
mSn–O), 419 (
m
Sn–N).
55.18; H, 6.25; N, 2.87; Cl, 7.36; Sn, 24.75%. H NMR (CDCl
3
) (ppm):
2 2
Scheme 3. Fragmentation pattern of [(n-Bu) Sn(sap) ] (2) derived from ESI-MS spectrum.

R.K. Dubey et al. / Inorganica Chimica Acta 410 (2014) 39–45
43
8
1
.50(1H, s, CH@N), 6.85–7.34(m, 8H, Ar–H), 2.33(3H, s, Ar–CH
.25–1.77(12H, m, Sn–(CH ) –), 0.84–0.90 (6H, m, CH
2 3 3
3
),
). C NMR
) (ppm): 161.70 (s, CO), 160.73 (s, CN), 132.57, 131.66,
ture (Scheme 1). All these complexes are colored solids, soluble in
polar solvents (e.g. methanol, ethanol, THF, DMF and DMSO).
1
3
(
DMSO-d
6
1
1
30.16, 126.48, 126.31, 118.81, 118.47, 117.19, 116.69 (s, Ar–C),
3
.1. Infrared spectral studies
n
119
7.65 (s, Ar–CH
3
), 26.77, 26.07, 25.73, 13.06 (s, Sn–Bu ).
Sn
),
À1
NMR (DMSO-d
6
6
) (ppm): À138.52. IR (KBr, cm ) 1599 (
m
C
@
N
The weak and broad bands, assigned to intramolecular hydro-
80 (mSn–C), 526 (mSn–O), 421 (mSn–N).
gen-bonded OH in the Schiff bases in the region 3484–
3
À1
430 cm , is not observed in the spectra of six di-n-butyltin(IV)
complexes [19], which is indicative of deprotonation of phenolic
2
.4.6. [(n-Bu)
Yield: 85%, dark yellow solid, m.p. 138–140 °C. Anal. Calc. for
Sn: C, 66.71; H, 6.48; N, 4.29; Sn, 18.17. Found: C,
2 2
Sn(p-smab) ](6)
hydrogen. This was further supported by the appearance of a
À1
new band in the 538–521 cm
region due to Sn–O stretching
C
6
8
1
36 42 2 2
H N O
1
mode [20]. In complexes the
m
(C@N), occurring between 1617–
6.14; H, 6.45; N, 4.24; Sn, 18.14%. H NMR (CDCl
.58(2H, s, CH@N), 6.53–7.42(m, 16H, Ar–H), 2.40(6H, s, Ar–CH
.33–1.67(12H, m, Sn–(CH ) –), 0.86–0.89(6H, m, CH
2 3 3
3
) (ppm):
),
). C NMR
) (ppm): 161.43 (s, CO), 160.30 (s, CN), 132.05, 131.40,
30.95, 128.87, 127.92, 125.90, 124.33, 121.36, 118.28, 118.21,
À1
1
596 cm , is considerably shifted towards lower frequencies with
3
À1
1
3
respect to that of the parent Schiff bases 1634–1616 cm , con-
firming the coordination of the azomethine nitrogen to dibutyl-
(
CDCl
3
tin(IV) moiety [15,16]. The weak intensity bands observed in the
1
1
À1
4
m
23–413 cm region may be due to
m
(Sn–N) vibration [21]. The
16.75 (s, Ar–C), 17.09 (s, Ar–CH
3
), 26.58, 26.36, 25.94, 12.60 (s,
À1
n
119
À1
(Sn–C) bands [20] were observed at 691–621 cm . On the basis
Sn–Bu ).
1
Sn NMR (DMSO-d
), 634 ( Sn–C), 521(
6
) (ppm): À389.51. IR (KBr, cm
)
of these observations, the structures of the complexes displayed
in Scheme 1 are more acceptable.
603 (
m
C
@
N
m
m
Sn–O), 413 (
mSn–N).
1
3
. Results and discussion
3.2. H NMR spectral studies
Organotin(IV) complexes (1–6) have been synthesized by the
interactions of di-n-butyltin(IV)dichloride with sodium salts of
Schiff bases in 1:1 and 1:2 stoichiometric ratios in THF-C mix-
The bidentate (O, N) connectivity [22,23] of the Schiff bases to
2
Sn moiety in complexes (1–6) is consistent with the (i) absence
of a signal assignable to phenolic OH in the 13.25–12.76 ppm
Bu
6
H
6
2
Fig. 1. TOF-MS spectrum of [(n-Bu) Sn(sap)Cl] (1).

4
4
R.K. Dubey et al. / Inorganica Chimica Acta 410 (2014) 39–45
region [16], (ii) appearance of a signal for azomethine H in the
.36–8.50 ppm region, which is downfield shifted [16] compared
to that observed for the corresponding Schiff bases in the 9.23–
.23 ppm region. The butyl group attached to tin showed two
broad peaks in the 0.90–0.83 and 1.79–1.18 ppm regions, respec-
tively due to –CH and (–CH –) groups of butyl chain [24].
For complexes (1) and (2), most of the fragment ions were ob-
served in the form of group of peaks due to the presence of various
isotopes of tin. In the spectra of (1) and (2) (Figs. 1 and 2) the
9
8
molecular ion peaks are observed at m/z 464.22 [(C20
2
H27ClN OSn)
(calculated mass = 466.08)] and 625.3 [(C32 Sn) (calculated
36 4 2
H N O
3
2
3
mass = 628.19)], respectively. In spectrum of the complex (1), the
base peak was observed due to the formation of phenoxy cation
+
1
3
[C H O] at about m/z 93, and other important peaks were also ob-
3
.3. C NMR spectral studies
6
5
served at m/z 429.13, 388.56, 367.22, 347.22, 303.16, 247.21,
n
Å
2
12.07, 120.14, 93.25 due to the formation of various radicals Bu ,
The presence of a downfield shifted signal in the region 161.71–
60.30 ppm [19,24,25] with respect to that observed (158.30–
56.51 ppm) for the corresponding parent Schiff bases is in support
of coordination of azomethine nitrogen to tin atom. The signal
which appears in the 151.56–149.70 ppm region for the carbon
atom adjacent to the phenolic oxygen in the spectra of free ligands,
is observed in the complexes 164.60–161.43 ppm region, which is
indicative of the bonding [20,25,26] through phenolic oxygen.
Å
Å
Å
Å
5 6 6 6
Cl , C H N , CHN, C H O , Sn in complex (1), whereas complex (2)
1
1
showed base peak at about m/z 355 due to the formation of frag-
Å+
ment [C14
10
H N
2
O
2
Sn] , some other prominent peaks were also ob-
served at m/z 577.3, 536.3, 503.3, 459.4, 429.2, 391.3, 318.2, 297.2,
n
Å
2
C
14.1, and 120.2 due to the formation of various radicals Bu ,
Å
Å
Å
5 6 6 6
H N , CHN, C H O , Sn .
3.6. DNA cleavage studies
1
19
3.4.
Sn NMR spectral studies
The organotin(IV) complexes (1–6) have been investigated for
their DNA cleavage activity by agarose gel electrophoresis method
18]. Lanes HSR1, HSR2, HSR3, HSR4, HSR5 and HSR6 of Fig. 3 rep-
resents the cleavage activity of the organotin(IV) complexes (1–6)
respectively, on the isolated DNA of Staphylococcus aureus and the
difference in the migration was observed compared to the control
DNA of S. aureus (Lane C). Control experiments clearly revealed
that, the untreated DNA does not show any cleavage (Fig. 3;
Lane-C1) whereas, all the metal complexes have exhibited cleavage
activity on DNA. The difference in the migration was observed in
The organotin(IV) complexes (1, 3, 5) and (2, 4, 6) exhibit a
1
19
single sharp
Sn resonance (see Experimental Section) in the
[
À139.88 to À138.52 and À389.51 to À309.94 ppm regions consis-
tent with penta- and hexa-coordinated tin atoms [27], respectively.
3
.5. Mass spectral studies
2
The mass spectral data for the complexes [(n-Bu) Sn(sap)Cl] (1)
2 2
and [(n-Bu) Sn(sap) ] (2) were recorded and different fragmenta-
tion patterns [13–16] have been suggested (Schemes 2 and 3).
the Lanes
1 HSR1, HSR2, HSR3, HSR4, HSR5 and HSR6 of
2
Fig. 2. ESI-MS spectrum of [(n-Bu) Sn(sap)Cl] (2).

R.K. Dubey et al. / Inorganica Chimica Acta 410 (2014) 39–45
45
to Mr. Suman Gupta, Department of Chemistry, University of Rajas-
1
13 119
than, Jaipur for recording H, C,
Sn NMR and TOF-MS spectra of
the complexes. The authors are also grateful to CDRI, Lucknow for
providing the analytical and ESI-MS data and IIT Bombay for IR
spectral facilities.
References
[
1] (a)M. Gielen, A.G. Davies, K. Pannell, E.R.T. Tiekink (Eds.), Tin Chemistry:
Fundamentals, Frontiers and Applications, Willey-Blackwell, 2008;
(
b) M. Nath, P.K. Saini, Dalton Trans. 40 (2011) 7077. and references cited
therein.
[
[
[
[
[
[
2] A.G. Davies, Organotin Chemistry, Second ed., Willey-VCH, Weinheim, 2004.
3] S.R. Collinson, D.E. Fenton, Coord. Chem. Rev. 148 (1996) 19.
4] H. Beraldo, D. Gambino, Med. Chem. 4 (2004) 159.
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London, 1998.
[
8] A.G. Davies, in: G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.), Comprehensive
Organometallic Chemistry II, Pergamon Press, Oxford, 1995.
Fig. 3. DNA cleavage study on genomic DNA of A. niger. M: Standard molecular
weight marker; C1: Control DNA of A. niger.
[9] N.K. Goh, C.K. Chu, L.E. Khoo, D. Whalen, G. Eng, F.E. Smith, R.C. Hynes, Appl.
Organomet. Chem. 12 (6) (1998) 457.
[
10] S.M. Santanu, B. Subbrangsu, J. Chem. Soc., Chem. Commun. (1995) 2489.
organotin(IV) complexes (1–6) respectively compared to the con-
trol DNA of A. niger (Lane-C1). This shows that, the control DNA
alone does not show any apparent cleavage whereas, organotin(IV)
complexes (1–6) shown. However, the nature of reactive interme-
diates involved in the DNA cleavage by the complexes has not been
clear. The results indicated the important role of metal ions in iso-
lated DNA cleavage reaction. From these results, we infer that the
organotin(IV) complexes (1–6) act as a potent nuclease agents. As
the compound was observed to cleave the DNA, which is indicative
of inhibiting the growth of the pathogenic organism by cleaving
the genome.
[11] S. Shujha, A. Shah, Z.U. Rehman, N. Muhammad, S. Ali, R. Quershi, N. Khalid, A.
Meetsma, Eur. J. Med. Chem. 45 (2010) 2902.
[
12] S. Tabassuma, R.A. Khan, F. Arjmand, S. Sen, J. Kayal, A.S. Juvekar, S.M. Zingde, J.
Organomet. Chem. 696 (2011) 1600.
[13] (a) R.K. Dubey, S. Pathak, Main Group Met. Chem. 31 (1–2) (2008) 29;
(
(
b) R.K. Dubey, P. Baranwal, A.K. Jha, J. Coord. Chem. 65 (15) (2012) 2645;
c) R.K. Dubey, U.K. Dubey, S.K. Mishra, J. Coord. Chem. Chem. 64 (13) (2011)
2292;
(d) R.K. Dubey, P. Baranwal, S.K. Dwivedi, U.N. Tripathi, J. Coord. Chem. 64 (15)
(
(
2011) 2649;
e) R.K. Dubey, U.K. Dubey, C.M. Mishra, Transition Met. Chem. 31 (7) (2006)
8
49;
(f) R.K. Dubey, U.K. Dubey, Indian J. Chem. 45A (2006) 1638;
c) R.K. Dubey, J. Indian Chem. Soc. 83 (2006) 1087.
(
[
[
14] R.K. Dubey, A.P. Singh, N. Dwivedi, J. Indian Chem. Soc. 88 (2011) 845.
15] R.K. Dubey, A.P. Singh, N. Dwivedi, Main Group Met. Chem. 34 (3–4) (2011) 77.
4
. Conclusion
[16] (a) R.K. Dubey, A.P. Singh, N. Dwivedi, Phosphorus, Sulphur Silicon Relat. Elem.
87 (2012) 1038;
b) R.K. Dubey, A.P. Singh, J. Coord. Chem. 66 (12) (2013) 2201.
1
(
Synthesis of five- and six-coordinate di-n-butyltin(IV) com-
[
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plexes have been achieved by the reactions of di-n-butyl-
tin(IV)dichloride with appropriate sodium salt of Schiff base
ligands in 1:1 and 1:2 molar ratios, respectively and investigated
by a variety of physicochemical methods. The DNA cleavage stud-
ies revealed that the complexes show non-specific cleavage of
DNA.
[
[
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A P S gratefully acknowledges the CSIR, New Delhi for Senior
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2