Organotin(IV) complexes of thiohydrazones: Synthesis, characterization and antifungal study

Article abstract of DOI:10.1016/j.saa.2004.11.035

Some new organotin(IV) complexes with salicylaldehyde aniline-N- thiohydrazone (L¹) and cinamaldehyde aniline-N-thiohydrazone (L ²) of the type (p-ClC₆H₄)₃Sn[L] Cl and (p-ClC₆H₄)₂Sn[L]Cl₂ have been synthesized (where L = L¹ and L²). The complexes and ligands were characterized by elemental analysis and spectral (UV-vis, IR and ¹H NMR) studies. In all the complexes, ligands act as bidentate, coordination through sulphur and azomethane nitrogen. Complexes are 1:1 metal ligands complexes. Antifungal studies of some complexes against Rhizoctonia bataticola fungal strain have been carried out.

Full text of DOI:10.1016/j.saa.2004.11.035

Spectrochimica Acta Part A 61 (2005) 3097–3101
Organotin(IV) complexes of thiohydrazones:
synthesis, characterization and
antifungal study
A.K. Mishra, N. Manav, N.K. Kaushik∗
Department of Chemistry, University of Delhi, Delhi-110007, India
Received 7 September 2004; accepted 2 November 2004
Abstract
Some new organotin(IV) complexes with salicylaldehyde aniline-N-thiohydrazone (L1) and cinamaldehyde aniline-N-thiohydrazone (L2)
of the type (p-ClC6H4)3Sn[L] Cl and (p-ClC6H4)2Sn[L]Cl2 have been synthesized (where L = L1 and L2). The complexes and ligands were
characterized by elemental analysis and spectral (UV–vis, IR and 1H NMR) studies. In all the complexes, ligands act as bidentate, coordination
through sulphur and azomethane nitrogen. Complexes are 1:1 metal ligands complexes. Antifungal studies of some complexes against
Rhizoctonia bataticola fungal strain have been carried out.
© 2004 Elsevier B.V. All rights reserved.
Keywords: Synthesis; Antifungal; Spectral; Organotin; Thiohydrazone
1. Introduction
2. Experimental
The organotin(IV) complexes possess significant biolog-
ical activities [1–4]. These complexes have been found as
antitumour [1], antibacterial [2], antifungal [3–5], antiviral
[6,7] and PVC-stabilizer [8]. They have been widely used as
agrochemicals and antifouling paints due to their low pho-
totoxicity and favourable environmental degradation [9] to
non-toxic inorganic tin residues. The work has been carried
out by many workers [3–5,10–17] by synthesizing and char-
acterizing the thiohydrazone complexes using different met-
als. In the present study, the authors have synthesized and
characterized some new organotin(IV) complexes using sali-
cylaldehyde aniline-N-thiohydrazone (complex 1 and 2) and
cinnamaldehyde aniline-N-thiohydrazone (complex 3 and 4)
ligands.
2.1. Physical measurements
All reagents used were AR grades and the solvents
were purified by standard method. IR and far IR spec-
tra were recorded on KBr and polyethylene discs, respec-
tively, using a Perkin-Elmer Spectrum 2000 FTIR spectrom-
eter, electronic (UV–vis) spectra were recorded on a Varian
1
cary 100 UV–vis spectrophotometer and H NMR spectra
were recorded on a Brucker spectrospin advance 300, Hi-
tachi R-600 FT NMR spectrometer 60. Elemental analysis
was carried out on Perkin Elmer 2400 series II CHN S/O
Analyser.
2.2. Preparation of organotin and ligands
p-Chlorotribenzyl tin chloride {(p-ClC6H4CH2)3SnCl}
and p-Chlorodibenzyl tin dichloride {p-ClC6H4CH2)2Sn-
Cl2} were synthesized by the method given by Sisido et al.
[18] All the ligands were synthesized in lab by Gilman and
Blatt [19] method with some modifications.
∗
Corresponding author. Tel.: +91 11 27667725x1391.
E-mail addresses: ajaykmishra1@yahoo.com (A.K. Mishra),
navneet92@rediffmail.com (N. Manav),
narenderkumar kaushik@yahoo.co.in (N.K. Kaushik).
1386-1425/$ – see front matter © 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2004.11.035

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A.K.Mishra et al./ Spectrochimica Acta Part A 61 (2005) 3097–3101
2.2.1. Preparation of thiohydrazide
refluxed in methanol for 3 h. On cooling, a yellow precipitate
obtained was filtered and washed with cold methanol. It
was recrystallised from hot methanol. The reactions in the
process are given below.
Aniline 18.2 ml (0.2 mol) (density 1.022) was dissolved
in methanol and potassium hydroxide 11.2 gm (0.2 mol)
in aqueous methanol was added with constant stirring in
methanolic ice cold solution of carbon disulphide 12.06 ml
(0.2 mol) (density 1.26) maintaining temperature below
10 ◦C. A white crystalline precipitate of aniline dithiocar-
bamate separated. Its aqueous solution was treated with
freshly prepared potassiumchloroacetate (0.05 mol). The
reaction temperature was maintained at 40 ◦C for an hour
and the content was left overnight at room temperature. After
24 h methanolic solution of 2.43 ml (0.05 mol) hydrazine
hydrate (density 1.03) was added to the reaction mixture.
The content was heated on water bath till the desired product
separated out. It was cooled in ice for 24 h and filtered.
Aniline-N-thiohydrazide so obtained was recrystallised from
hot water. The reactions are given below.
Analysis; found (calc.)% C, 68.42(68.33); H, 5.73(5.34);
N, 15.07(14.95)
Analysis; found (calc.)% C, 50.07(50.29); H, 5.42(5.38);
N, 25.18(25.38)
2.2.2. Preparation of salicylaldehyde
aniline-N-thiohydrazone (L1)
2.3. Preparation of thiohydrazone complexes
Aniline-N-thiohydrazide 4.2 g (0.025 mol) and sal-
icylaldehyde 2.7 ml (0.025 mol) (1.146 density) were
refluxed in methanol for 3 h. On cooling, a yellow pre-
cipitate obtained was filtered and washed with cold methanol.
A solution of corresponding thiohydrozones, salicylalde-
hyde aniline-N-thiohydrazone [L1, 0.54 g (0.002 mol)] and
a solution of cinnamaldehyde aniline-N-thiohydrazone [L2,
0.56 g (0.002 mol)] in 25 ml of acetone solution [1:7 (distilled
water:acetone mixture was added)] slowly added to corre-
sponding organotin chloride R3SnCl or R2SnCl2 (0.002 mol)
in 25 ml of [1:7 (distilled water:acetone)] mixture. The mix-
ture so obtained was refluxed for half an hour, stirred contin-
uously for additional 4 h and then evaporated to one-fourth
of its original volume under vacuum. The complex so ob-
tained was recrystallised in acetone, washed with petroleum
ether and dried in a desiccator over CaCl2 (where R = p-
ClC6H4CH2).
Analysis; found (calc.)% C, 61.34(61.99); H, 4.80(4.38);
N, 15.50(14.36)
It was recrystallised from hot methanol. The reactions in
the process are given above.
3. Results and discussion
2.2.3. Preparation of cinnamaldehyde
Elemental analysis reveals that complexes are of good pu-
rity. All the synthesized complexes are soluble in acetone and
DMSO solvents (Table 1). These are amorphous and grey in
colour.
aniline-N-thiohydrazone (L2)
Aniline-N-thiohydrazide 4.2 g (0.025 mol) and cin-
namaldehyde 3.2 ml (0.025 mol) (1.048 density) were

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3099
Table 1
Elemental analysis of thiohydrazone complexes
Complexes
Melting point (◦C)
and solubility
Empirical formula
Found (calc.) (%)
Sn Cl
C
H
N
(p-ClC6H4CH2)3Sn(L1)Cl
124 Acetone and DMSO C33H31SnN3OSCl4 14.16 (14.84) 17.65 (17.71) 52.32 (52.37) 4.38 (3.87) 5.57 (5.24)
28H25SnN3OSCl4 15.74 (16.71) 20.14 (19.94) 46.36 (47.19) 3.59 (3.51) 5.86 (5.90)
(p-ClC6H4CH2)2Sn(L1)Cl2 118 Acetone and DMSO
C
(p-ClC6H4CH2)3Sn(L2)Cl
(p-ClC6H4CH2)2Sn(L2)Cl2 113 Acetone and DMSO
127 Acetone and DMSO C37
H33SnN3SCl4
14.86 (14.66) 17.32 (17.49) 54.93 (54.68) 4.12 (4.06) 5.23 (5.17)
16.93 (16.49) 19.45 (19.67) 50.02 (49.86) 3.82 (3.74) 6.04 (5.82)
C30H27SnN3SCl4
Table 2
Table 4
UV–vis spectra of thiohydrazone complexes
1H NMR Spectra analysis of thiohydrazone complexes
Complexes
L1
λmax
Absorbance
Complexes
Ar–H
–CH2
–NHa and –NHb
270.32
315.26
2.36
1.16
L1
6.8–7.7 (m-9H)
7.1–7.3 (d-21H)
–
8.2 and 7.2 (s-1H)
8.5–8.7 and 7.5–7.7
(s-1H)
8.2 and 7.2 (s-1H)
8.6 and 7.5 (s-1H)
8.16 and 6.9 (s-1H)
8.5 and 7.4 (s-1H)
8.16 and 6.9 (s-1H)
8.3 and 7.2 (s-1H)
Complex 1
3.4 (s-6H)
Complex 1
L1
261.67
293.33
2.42
1.23
L1
6.8–7.7 (m-9H)
7.0–7.2 (d-17H)
6.5–7.8 (m-10H)
6.9–7.1 (d-22H)
6.5–7.8 (m-10H)
6.8–7.0 (d-18H)
–
Complex 2
L2
Complex 3
L2
3.3 (s-4H)
–
3.6 (s-6H)
–
3.4 (s-4H)
270.32
315.26
2.36
1.16
Complex 4
Complex 2
L2
261.60
300.00
2.58
1.98
3.2. I R spectra
267.43
323.46
2.18
1.46
In IR spectra, ν(C N) and ν(N N) shift to higher fre-
quency on complexation showing the involvement of azome-
thine nitrogen [20] in coordination and ν(C S) frequency
from ∼800 cm−1 shifts to ∼825 cm−1 indicates coordina-
tion of ligands through thione sulphur. −T1he metal complexes
also show ν(Sn S) [21] at ∼350 cm , ν(Sn N) [22] at
∼480 cm−1 and νSn Cl [21] at ∼315 cm−1. These indicate
that ligands are coordinated to the metal through thione sul-
phur and azomethine nitrogen (Table 3). On comparing with
the other synthesized compounds [4,5,25], the ν(C S) and
ν(C N) frequency shift indicates more stable coordination
on complexation.
Complex 3
L2
266.00
309.16
2.38
1.87
267.43
323.46
2.18
1.46
Complex 4
267.33
305.83
2.36
1.56
3.1. Electronic spectra
In the electronic spectra [4,25] due to chromophore re-
*
3.3. 1H NMR spectra
gion, absorption bands at ∼300 nm are assigned as ␲–␲
intraligand electronic transition (N C S). In UV spectra of
ligand (L1) two absorption bands at 270 nm (log ε = 3.37)
and 315 nm (log ε = 3.06). Ligand (L2) absorbs at 267 nm
(log ε = 3.34) and 323 nm (log ε = 3.16). On complexation
these bonds are shifted lower revealing involvement of C S
group coordination in all the complexes (Table 2).
In 1H NMR spectra [23–25] of complexes were recorded
in d6-DMSO taking TMS as internal standard (Table 4). The
shift observed in the region δ (ppm) 6.5–7.8 (Ar–H), 8.7–6.9
(NHa and NHb) and 3.4–3.6 (–CH2) on complexation. The
shift in the position of resonance signal of the complexes to
Table 3
IR Spectra of thiohydrazone complexes
Complexes
ν(C N)
ν(C O)
ν(N H)
ν(N N)
ν(C S)
ν(M S)
ν(M Cl)
ν(M N)
ν(C H)
L1
1591
1595
1591
1596
1593
1605
1593
1607
1240
1242
1240
1241
–
–
–
–
3216
3207
3216
3208
3201
3180
3201
3186
1008
1027
1008
1015
1003
1017
1003
1023
809
827
809
824
932
945
932
956
–
354
–
358
–
343
–
350
–
315
–
325
–
310
–
317
–
480
–
481
–
502
–
509
2926
2929
2926
2936
2926
2928
2926
2930
Complex 1
L1
Complex 2
L2
Complex 3
L2
Complex 4

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4. Conclusion
On the basis of elemental analysis, spectral (UV,
IR, 1H NMR) data; the following structures representing
donation, have been proposed for the complexes synthesized.
Fig. 1. Antifungal study against Rhizoctonia bataticola of complex 1.
Fig. 2. Antifungal study against Rhizoctonia bataticola of complex 2.
ligand due to change in the electronic environment as a result
of coordination of the ligands to the metal.
On comparing with the other synthesized compounds
[4,25], significant change in the δ (ppm) value has been ob-
served.
3.4. Antifungal screening
The organotin(IV) complexes show very high antimicro-
bial and fungicidal activities [4,26] against pathogenic strains
of Rhizoctonia bataticoala. The compounds were directly
mixedwiththemediumindifferentthreeconcentrations(250,
500, 1000 ␮g mL−1) in ethanol. The growth of fungus was
measured by the recording the diameter of fungal colony.
The relation for calculation of fungal growth inhibition: fun-
gal growth inhibition % = (A – B) × 100 /A, where A is the
diameter of fungal colony in control plate and B is the diam-
eter of the fungal colony in taste plate. The results show that
organotin(IV) complexes (Figs. 1 and 2) are found to be active
against pathogen Rhizoctonia bataticoala and show a higher
percentage of inhibition at higher concentration (Table 5). A
significant enhancement in the antifungal activity has been
observed in the present investigations when compared with
other biologically active compounds [26].
Complex 1: Tri [(p-chlorobenzyl) tin (salicylaldehyde
aniline-N-thiohydrazone)] chloride;
Complex 2: Di [(p-chlorobenzyl) tin (salicylaldehyde
aniline-N-thiohydrazone)] dichloride;
Complex 3: Tri [(p-chlorobenzyl) tin (cinnamaldehyde
aniline-N-thiohydrazone)] chloride;
Complex 4: Di [(p-chlorobenzyl) tin (cinnamaldehyde
aniline-N-thiohydrazone)] dichloride.
Acknowledgement
The authors are thankful to Dr. R.L. Gupta, Division of
Agricultural Chemicals, IARI, New Delhi, for the antifungal
studies of the complexes.
Table 5
Antifungal study against Rhizoctonia bataticola of thiohydrazone complexes
Complexes
Complex 1
Conc. (ppm)
Inhibition (%)
Fungal growth
diameter (cm)
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