Synthesis, characterization, semi-empirical study, and biological activities of organotin(IV) complexes with cyclohexylcarbamodithioic acid as biological active ligand

Article abstract of DOI:10.1080/00958972.2012.657185

Cyclohexylcarbamodithioic acid has been synthesized by the reaction of cyclohexylamine with carbon disulfide at room temperature. Its complexes have been synthesized by the reaction of cyclohexylcarbamodithioic acid with organotin(IV) chlorides in 1 : 1/1

Full text of DOI:10.1080/00958972.2012.657185

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Synthesis, characterization, semi-
empirical study, and biological
activities of organotin(IV) complexes
with cyclohexylcarbamodithioic acid as
biological active ligand
Saba Jabbar a , Iram Shahzadi a , Rafia Rehman a , Humaira Iqbal
a , Qurat-Ul-Ain a , Aneela Jamil a , Rubina Kousar a , Saqib Ali
b , Saira Shahzadi a , Muhammad Aziz Choudhary c , Muhammad
Shahid d , Qaiser Mehmood Khan e , Saroj K. Sharma f & Kushal
Qanungo f
a Department of Chemistry , GC University , Faisalabad , Pakistan
b Department of Chemistry , Quaid-i-Azam University ,
Islamabad-45320 , Pakistan
c Department of Chemistry , Mirpur University of Science and
Technology , Mirpur Azad Jammu and Kashmir , Pakistan
d Department of Chemistry and Biochemistry , University of
Agriculture , Faisalabad , Pakistan
e Environmental Biotechnology Division , NIBGE, P.O. Box 577,
Jhang Raod, Faisalabad , Pakistan
f Department of Applied Science and Humanities, Faculty of
Engineering and Technology , Mody Institute of Technology and
Science (Deemed University) , Lakshmangargh-332311, Dist Sikar,
Rajasthan , India
Published online: 02 Feb 2012.
To cite this article: Saba Jabbar , Iram Shahzadi , Rafia Rehman , Humaira Iqbal , Qurat-Ul-
Ain , Aneela Jamil , Rubina Kousar , Saqib Ali , Saira Shahzadi , Muhammad Aziz Choudhary ,
Muhammad Shahid , Qaiser Mehmood Khan , Saroj K. Sharma & Kushal Qanungo (2012) Synthesis,
characterization, semi-empirical study, and biological activities of organotin(IV) complexes with
cyclohexylcarbamodithioic acid as biological active ligand, Journal of Coordination Chemistry, 65:4,
572-590, DOI: 10.1080/00958972.2012.657185
To link to this article: http://dx.doi.org/10.1080/00958972.2012.657185

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Journal of Coordination Chemistry
Vol. 65, No. 4, 20 February 2012, 572–590
Synthesis, characterization, semi-empirical study,
and biological activities of organotin(IV) complexes with
cyclohexylcarbamodithioic acid as biological active ligand
SABA JABBARy, IRAM SHAHZADIy, RAFIA REHMANy, HUMAIRA IQBALy,
QURAT-UL-AINy, ANEELA JAMILy, RUBINA KOUSARy, SAQIB ALI*z,
SAIRA SHAHZADI*y, MUHAMMAD AZIZ CHOUDHARYx,
MUHAMMAD SHAHID{, QAISER MEHMOOD KHAN?,
SAROJ K. SHARMAk and KUSHAL QANUNGOk
yDepartment of Chemistry, GC University, Faisalabad, Pakistan
zDepartment of Chemistry, Quaid-i-Azam University, Islamabad-45320, Pakistan
xDepartment of Chemistry, Mirpur University of Science and Technology,
Mirpur Azad Jammu and Kashmir, Pakistan
{Department of Chemistry and Biochemistry, University of Agriculture,
Faisalabad, Pakistan
?Environmental Biotechnology Division, NIBGE, P.O. Box 577,
Jhang Raod, Faisalabad, Pakistan
kDepartment of Applied Science and Humanities, Faculty of
Engineering and Technology, Mody Institute of Technology and Science
(Deemed University), Lakshmangargh-332311, Dist Sikar, Rajasthan, India
(Received 15 August 2011; in final form 9 December 2011)
Cyclohexylcarbamodithioic acid has been synthesized by the reaction of cyclohexylamine with
carbon disulfide at room temperature. Its complexes have been synthesized by the reaction
of cyclohexylcarbamodithioic acid with organotin(IV) chlorides in 1 : 1/1 : 2 molar ratio. The
ligand and complexes have been characterized by elemental analysis, infrared (IR), and
multinuclear (1H, 13C, and 119Sn) NMR spectroscopy. Elemental data show good agreement
between calculated and found values of carbon, hydrogen, nitrogen, and sulfur. IR data show
that the ligand is bidentate and complexes exhibit a five-coordinate geometry in the solid state,
which is also confirmed by semi-empirical studies. NMR data show that the complexes exhibit
tetrahedral geometry in solution state. The ligand and its complexes were screened for their
in vitro mutagenic, antimicrobial, MIC, antioxidant activities, and cytotoxicity. Biological
screening data demonstrate that complexes show significant activity against various bacterial
and fungal strains and are good antioxidants. The cytotoxicity data show positive lethality for
complexes as compared to ligand and can play a very significant role in drug development.
Keywords: Organotin(IV) complexes; IR; NMR; Mutagenic; Antimicrobial; MIC;
Antioxidant; Cytotoxicity; Semi-empirical study
*Corresponding authors. Email: drsa54@yahoo.com; sairashahzadi@hotmail.com
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2012.657185

Cyclohexylcarbamodithioic acid
573
1. Introduction
Organotin compounds are among the most widely used organometallic compounds [1].
Industrial use of non-toxic organotin compounds (R2SnX2 and RSnX3) account for
almost two-thirds of the total world consumption [2], although the other major use of
these derivatives is their selectivity for a variety of biological applications including
fungicides, anti-fouling agents [3–5], anti-inflammatory agents [6], pesticides [1], and
cardiovascular [7]. In addition to extensive biological applications, anti-tumor and
anti-cancer activities of such compounds have made them important [6]. The number
and diversity of sulfur chelating agents used to prepare new coordination and
organometallic compounds have increased rapidly because they provide an interesting
series of ligands whose properties can be modified by introducing different organic
substituents, thereby causing variation in the donor properties. The interaction of these
donors with metal ions gives complexes of different geometries and properties which
have potential for biological applications [8]. Metal thiolato complexes have been
studied because of their ability to adopt various nuclearities and their relevance
in biology [9–12], since they form the inorganic part of the biologically active centers
of some metalloproteins and enzymes [13]. Dithiocarbamates are active against
fungi [14, 15] and insects [16]. The aim of this work is to prepare new organotin(IV)
derivatives with cyclohexylcarbamodithioic acid. All these compounds have
been characterized by elemental analyses, infrared (IR), and multinuclear NMR
(1H, 13C, and 119Sn) spectroscopy. In addition, these compounds were tested for
their in vitro mutagenic, antimicrobial, minimum inhibitory concentration (MIC),
antioxidant, and hemolytic activities.
2. Experimental
2.1. Chemicals and instrumentation
Cyclohexylamine, ethanol, carbon disulfide, and organotin chlorides were purchased
from Aldrich Chemical Company (USA). Sodium carbonate (Na2CO3), Na2HPO4,
KH2PO4, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and methanol were purchased from
Merck (UK). Nutrient agar, nutrient broth, and potato dextrose agar (PDA) were
purchased from Oxoid Company (UK). All reagents used were of analytical grade.
The melting points were determined in capillary tube on an electrothermal melting
point apparatus, model Stuart (SMP3) (UK) and are uncorrected. IR spectra were
recorded using a Perkin-Elmer 1000 FT-IR Spectrophotometer as KBr discs/thin
films from 4000 to 250 cmꢀ1. NMR spectra were recorded on a Bruker AM-250 MHz
FT-NMR spectrometer (Germany) using deuterated CDCl3 as internal reference. The
percentage composition of C, H, N, and S were determined by using a CHNS-932 Leco
(USA). The antimicrobial activities of the ligand and organotin(IV) complexes have been
performed in an incubator (Sanyo, Germany) and sterilized in an autoclave (Omron,
Japan). The MIC and antioxidant activities were determined in a Micro Quant apparatus
(BioTek, USA). Centrifuge H-200 NR (Kokusan, Japan) was used to centrifuge the
sample solutions and Haemacytometer (Fisher Ultra Plane, Japan) used to count the
RBC in cyctotoxic assay. Colony counter GW-92CL, Go Won Scientific Technology
Co., Seoul, Korea has been used for counting the colonies in mutagenic activity.

574
S. Jabbar et al.
The molecules were modeled by MOPAC2007 [17] program in the gas phase using the
PM3 method [18, 19]. Selected parts of the complexes not containing the metal ion were
pre-optimized using molecular mechanics methods. Several cycles of energy minimiza-
tion had to be carried out for each molecule. Geometry was optimized using
Eigen Vector. The root-mean-square gradients for molecules were all less than one. Self
consistent field was achieved in each case.
2.2. Synthesis of cyclohexylcarbamodithioic acid
Cyclohexylamine (0.09 mL, 1 mmol) was dissolved in ethanol (25 mL) in a round
bottom flask and stirred for 15 min at room temperature. Then carbon disulfide
(0.06 mL, 1 mmol) was added dropwise to the above solution with constant stirring. The
reaction mixture was continuously stirred for 2 h at room temperature. The off-white
precipitates formed were filtered, washed with ethanol, and air dried. Purity was
checked by TLC.
S
H
C
NH2
ethanol
N
SH
CS2
+
2 hrs stirring
2.3. General procedure for synthesis of organotin(IV) complexes
Cyclohexylcarbamodithioic acid (1 mmol) was dissolved in chloroform (90 mL) in
a round bottom flask under continuous stirring for 15 min at room temperature.
Then R2SnCl2 (1 : 1/1 : 2)/R3SnCl and L (1 : 1) ratio was added in portions to the
reaction flask and the reaction mixture was stirred for 5–6 h. The light yellow
precipitates formed were filtered off and dried in open air. Purity was checked by TLC.
H
N
S
C
SH
+
R2SnCl2
5–6 hrs
Stirring
R
H
N
S
Sn
R
Y
C
S
R= Me , n-Bu 2, Me
1
3
H
N
S
S
C
3
Y =
Cl
, ,
1 2

Cyclohexylcarbamodithioic acid
575
H
N
S
C
SH
R3SnCl
+
5–6 hrs
Stirring
R
H
N
S
Sn
R
C
S
R
R= Me , n-Bu , Ph
6
4
5
2.4. Antibacterial assay
2.4.1. Bacterial growth medium, cultures, and inoculums preparation. Pure cultures
were maintained on nutrient agar medium in petri plates. For the inoculums
preparation, 13 g Lꢀ1 of nutrient broth was suspended in distilled water, mixed well,
and distributed homogeneously. Then autoclaved 10 mL of pure culture of a bacterial
strain was mixed in the medium and placed in a shaker for 24 h at 37ꢁC. The inocula
were stored at 4ꢁC. The inocula with 1 ꢂ 108 spores mLꢀ1 were used for further analysis.
2.4.2. Antibacterial assay by the disc diffusion method. Antibacterial activity of
samples was determined by using the disc diffusion method [20, 21]. Nutrient agar
28 g Lꢀ1 was suspended in distilled water, mixed well, and distributed homogeneously.
The medium was sterilized by autoclaving at 121ꢁC for 15 min. Before the medium was
transferred to petri plates, inoculums (100 mL/100 mL) were added to the medium and
poured in sterilized petri plates.
After this, small filter paper discs were laid flat on the growth medium containing
100 mL of sample solution. The petri plates were then incubated at 37ꢁC for 24 h, for the
growth of bacteria. The sample having antibacterial activity inhibited the bacterial
growth and clear zones were formed. The zones of inhibition were measured in
millimeters using a zone reader [22].
2.5. Antifungal assay
2.5.1. Growth medium, cultures, and inoculum preparation. Pure cultures of the fungi
were maintained on PDA medium in slant or petri plates that were pre-sterilized in hot
air oven at 180ꢁC for 3 h. These culture slants were incubated at 28ꢁC for 3–4 days for
the multiplication of fungal strains.
2.5.2. Antifungal assay by the disc diffusion method. The prepared sterilized growth
medium was transferred to the sterilized petri plates. The petri plates were then

576
S. Jabbar et al.
incubated at 28ꢁC for 48 h, for the growth of fungus. Small filter paper discs were laid
flat on the growth medium having fungal growth and 100 mL of each sample was
applied on each disc. The petri plates were again incubated. The samples having
antifungal activity exhibit clear zones around the discs. The zones of inhibition were
measured in millimeters using a zone reader [22].
2.6. Minimum inhibitory concentration
The MIC was determined by the modified resazurin assay utilizing microtiter-
plate [23].
2.6.1. Preparation of bacterial and fungal culture. Using aseptic technique a single
colony was transferred to 100 mL bottle of nutrient broth, capped and placed in an
incubator overnight at 37ꢁC. After 12–18 h of incubation using aseptic preparation and
the aid of a centrifuge, a clean sample of bacteria was prepared. The broth was spun
down using the centrifuge at 4000 rpm for 5 min. The supernatant was discarded into an
appropriately labeled and contaminated waste beaker.
The pellet was re-suspended using 20 mL of sterile normal saline and centrifuged
again at 4000 rpm for 5 min. This step was repeated until the supernatant was clear.
The pellet was suspended in 20 mL normal saline and was labeled. The optical density
of bacterial culture was recorded at 500 nm and serial dilutions were carried out
with appropriate aseptic technique until the optical density was in the range 0.5–1.0.
The actual number of colony forming units was calculated from the viability graph.
The dilution factor needed was calculated and the dilution was carried out to obtain
a concentration of 5 ꢂ 106 CFU mLꢀ1. The fungal culture was prepared by the same
procedure as described in antifungal activity.
2.6.2. Procedure for MIC. Plates were prepared under aseptic condition. A sterile 96
well plate was labeled. A volume of 100 mL of test material was pipetted out into
the first row of the plate. To all other wells 50 mL of nutrient broth was added.
Serial dilutions were performed. Tips were discarded after use such that each well had
50 mL of the test material in serially descending concentration. To each well 10 mL
of resazurin indicator solution was added. Finally, 10 mL of bacterial suspension
(5 ꢂ 106 CFU mLꢀ1) was added to achieve a concentration of 5 ꢂ 105 CFU mLꢀ1
.
Each plate had a set of controls: (i) A column with a broad spectrum antibiotic
as positive control; (ii) A column with all solutions except test compound; and (iii) a
column with all solutions with the exception of the bacterial solution adding 10 mL
of broth instead. Each plate was wrapped to ensure that bacteria did not dehydrate.
The plates were then incubated at 28ꢁC for 48 h for fungus and at 37ꢁC for 24 h for
bacteria. The absorbance was recorded at 620 nm by micro quant for fungus and
at 500 nm for bacteria. Any color change from purple to pink or colorless was
recorded as positive. The lowest concentration at which the color change occurred was
taken as MIC value [23].

Cyclohexylcarbamodithioic acid
2.7. DPPH radical scavenging assay
577
The DPPH assay was carried out as described by Bozin [24]. The antioxidant activity of
samples was assessed by measuring their scavenging abilities of the stable 2,2-diphenyl-
1-picrylhydrazyl radical (DPPH). Aliquot (50 mL) of various concentrations of the
samples was added to 5 mL of a 0.004% methanol solution of DPPH. After 30 min
incubation period at room temperature, the absorbance was read against a blank at
517 nm. The assay was carried out in triplicate.
Ið%Þ ¼ ðAblank ꢀ AsampleAblankÞ ꢂ 100
Ablank is the absorbance of the control reaction (containing all reagents except the test
compound) and Asample is the absorbance of the test compound. Sample concentration
providing 50% inhibition (IC50) was calculated from the graph which was obtained by
plotting inhibition percentage against sample concentration.
2.8. Hemolytic activity
Hemolytic activity was checked by using Powell’s method [25]. Freshly obtained
heparinized human blood (3 mL) was gently mixed with 2–3 drops of heparin, poured
into a sterile 15 mL falcon tube and centrifuged for 5 min at 3000 rpm. The supernatant
was poured off and viscous pellet was washed three additional times with sterile isotonic
phosphate-buffered saline (PBS) solution, and adjusted to pH ꢃ7.4. To stabilize the pH,
the sample was mixed for half an hour at room temperature (25–30ꢁC). The washed
cells were suspended in the 20 mL chilled, saline PBS buffer. Erythrocytes were counted
on a haemacytometer.
The blood cell suspension was maintained on wet ice and diluted with sterile PBS.
The cell count should be 7.068 ꢂ 108 cells per mL for each assay. 20 mL of sample
solution (10%) was taken in 2 mL Apendoff tubes. For each assay, 0.1% Triton X-100
was taken as a positive control, i.e., 100% of blood lysis and PBS was taken for each
assay as a negative control, i.e., background (0% lysis). In each 2 mL Apendoff already
containing 20 mL sample, 180 mL diluted blood cell suspension was added and mixed
with the help of the pipette tip. Tubes were incubated for 35 min at 37ꢁC and agitated
after 10 min. Immediately after incubation, the Apendoff tubes were placed on ice
for 5 min and then centrifuged for 5 min at 4200 rpm. After centrifugation, 100 mL
supernatant was taken from the tubes and diluted with 900 mL chilled PBS. All tubes
were maintained on wet ice after dilution.
Then 200 mL was taken into 96 well plates and three replicates were taken in well
plates which contain one positive control (100% of blood lysis) and another negative
control (0% of blood lysis). After this, absorbance at 576 nm recorded on micro Quant.
Triton X-100 (0.1%) were used as positive control for 100% lysis and PBS buffer as
negative control 0% lysis. The experiment was done in triplicate and mean ꢄ SD was
calculated by using the following % hemolysis formula:
HbABS
% hemolysis ¼
ꢂ 100:
Hb100 %ABS
Data observed were expressed in % of cell lysis by comparing with 100% hemolysis
of the same number of cells using 0.1% Triton X-100 as positive standard [25].

578
S. Jabbar et al.
2.9. Statistical analysis
The values obtained are given as means ꢄ SD of each measurement. Where appropriate,
the data were tested by one-way ANOVA using Minitab 13. Pearson correlation
coefficients and p-values were used to show correlations and their significance.
Differences of p 5 0.05 were considered significant [26].
2.10. Mutagenic activity
The mutagenic potential was evaluated by the Ames test [27] through the plate
incorporation method. The plate incorporation test consists of combining the test
compound and bacterial tester strain in soft top agar which is poured onto the minimal
agar plates; positive and negative controls are also included in each assay. After
incubation at 37ꢁC for 48 h revertant colonies are counted. The same method was
followed by just increasing the time of incubation because the size of revertant colonies
after 48 h remained too small to be counted easily. So, the time of incubation was
increased to 60 h. Top agar tubes containing 2 mL top agar were prepared and
autoclaved. Tubes were heated to melt the top agar and were placed in a heating
block at 45ꢁC. Histidine/biotin (his/bio) 0.5 mmol Lꢀ1 solution was prepared and filter
sterilized by using autoclaved filter assemblies with 0.22 mmol Lꢀ1 filter paper discs.
Filtered samples were used for testing their mutagenicity. 100 mL of test sample was
added to these tubes. Then 100 mL of overnight grown culture of test strain containing
approximately 3 ꢂ 107 cell mLꢀ1 and OD 0.7–0.8 at 590 nm was added. The tube was
vortexed and then immediately poured onto the medium plates. The plates were tilted
and rotated quickly for even spreading of top agar mixture over the whole surface of the
plates, which were then placed on a level surface to harden. For each experiment plates
were used in triplicate. All samples were checked with TA98 and TA100. Positive and
negative controls were also used for each test. As a negative control 100 mL autoclaved
DMSO was used. As a positive control, potassium dichromate (10 mg/plate) was used
for TA98 and the same amount of sodium azide was used for TA100. This process
was carried out with great care under aseptic conditions by using laminar air flow and
gas burner. Plates were incubated at 37ꢁC for 60 h and the revertant colonies on test and
control plates were counted on the colony counter. The presence of background lawn
on the negative control plate is evidence of bacterial toxicity. In the negative control,
spontaneously revertant colonies were also found for both strains. Single-lines were
streaked on nutrient agar plates by sterilized wire loop from all test samples and
solutions for sterility testing and from bacterial cultures for their viability. Mutagenicity
index (MI) was calculated by the following formula:
No: of revertant colonies in test plate
Mutagenicity index ðMIÞ ¼
No: of revertant colonies in negative control plate
3. Results and discussion
The synthesized cyclohexylcarbamodithioic acid and organotin(IV) complexes are
solids and stable in air. They have sharp melting points and are soluble in common

Cyclohexylcarbamodithioic acid
579
Table 1. Physical data of cyclohexylcarbamodithioic acid and its organotin(IV) complexes.
Elemental analysis
Compound
number
Molecular
formula
m.p. Yield % C Calcd % H Calcd % N Calcd % S Calcd
m.w. (ꢁC) (%)
(found) (found) (found) (found)
HL
1
2
C7H13NS2
175.32 181 64 47.96 (47.92) 7.47 (7.51) 7.99 (7.95) 36.58 (36.62)
C9H18NS2SnCl 358.54 155 96 30.15 (30.11) 5.16 (5.02) 3.91 (3.95) 17.89 (17.93)
C15H30NS2SnCl 442.2 201 77 40.77 (41.74) 6.83 (6.87) 3.16 (3.12) 14.49 (14.53)
C16H30N2S4Sn 497.4 130 54 38.64 (38.68) 6.08 (6.94) 5.63 (5.59) 25.79 (25.74)
3
4
5
6
C10H21NS2Sn
C19H39NS2Sn
C25H27NS2Sn
338.19 195 55 35.52 (35.56) 6.26 (6.22) 4.14 (4.18) 18.97 (18.93)
464.36 209 64 49.14 (49.10) 8.47 (8.51) 3.02 (3.06) 13.81 (13.77)
524.33 111 93 57.27 (57.31) 5.19 (5.15) 2.67 (2.63) 12.23 (12.27)
Table 2. Characteristic IR bands (cmꢀ1
complexes.
) of cyclohexylcarbamodithioic acid and its organotin(IV)
Compound number ꢀ(N–H)
ꢀ(S–H)
ꢀ(C–N) ꢀ(C¼S) ꢀ(C–S) ꢀ(Sn–C)
ꢀ(Sn–S) ꢀ(Sn–Cl)
HL
1
2
3
4
3463
3467
3368
3467
3367
3468
3466
2749
1446
1447
1444
1447
1446
1444
1449
1087
1082
1078
1079
1073
1085
1072
943
982
960
982
954
920
920
–
–
–
368
358
–
–
–
–
–
–
–
–
–
558
551
550
551
555
342
453
449
450
440
456
440
5
6
–
organic solvents. Elemental analysis was done to compare the observed values of
percentage of carbon, hydrogen, nitrogen, and sulfur in the cyclohexylcarbamodithioic
acid and its complexes with those of predicted values. The observed values are in good
agreement with the calculated values. The physical data of cyclohexylcarbamodithioic
acid and organotin(IV) complexes are summarized in table 1.
3.1. IR spectroscopy
IR spectra of HL and complexes were recorded as KBr discs/thin films from 4000 to
250 cmꢀ1. The values of different vibrational frequencies were assigned to different
bonds by comparing spectra of ligand and complexes. Complexation through sulfur was
confirmed by disappearance of ꢀS–H in spectra of the complexes [28]. This band appears
at 2749 cmꢀ1 in spectra of the ligand. The appearance of medium intensity bands due
to ꢀSn–S and ꢀSn–Cl in the complexes at 456–440 cmꢀ1 and 368–358 cmꢀ1, respectively,
further confirm complexation. The presence of a single band at 1072–1085 cmꢀ1 is
assigned to ꢀC–S and its relatively high value suggests that dithiocarbamate is linked
to Sn bidentate. The complexes do not show any significant shift in ꢀN–H, confirming
that complexation does not take place through nitrogen.
The medium to sharp intensity band that appears at 558–342 cmꢀ1 was assigned
to ꢀSn–C (table 2). The band at 982–920 cmꢀ1 in spectra of complexes was assigned to
ꢀC–S and was important to confirm the bidentate mode of the ligand [29].

580
S. Jabbar et al.
Table 3. 1H NMR dataa–c of cyclohexylcarbamodithioic acid and its organotin(IV) complexes.
Chemical shift (ppm)
Proton
HL
1
2
3
4
5
6
2
3.14 s
3.14 s
3.13 s
3.14 s
3.13 s
3.14bs
3.14bs
3
3.61–3.65 m 3.60–3.66 m 3.61–3.65 m 3.61–3.66 m 3.60–3.66 m 3.60–3.66 m 3.61–3.65 m
1.74–1.79 m 1.74–1.79 m 1.74–1.79 m 1.74–1.78 m 1.73–1.78 m 1.74–1.79 m 1.74–1.78 m
1.58–1.65 m 1.58–1.66 m 1.58–1.65 m 1.57–1.66 m 1.58–1.65 m 1.58–1.65 m 1.57–1.65 m
1.39–1.47 m 1.39–1.47 m 1.39–1.47 m 1.39–1.46 m 1.39–1.49 m 1.39–1.47 m 1.39–1.47 m
4,40
5,50
6
a(1) Sn–CH3Cl, 1.55 s 2J[96]; (2) Sn–CH2CH2CH2CH3Cl, 0.88–0.93 m, 0.23 t (7.2); (3) Sn–CH3, 1.35 s 2J[90]; (4) Sn–CH3,
0.51 s 2J[82]; (5) Sn–CH2CH2CH2CH3, 0.64–1.1 m, 0.23 t (7.2); (6) Sn–C6H5, 7.91 d 2J[57.2], 7.50–7.53 m, 7.42–7.50 m.
bChemical shifts (ꢁ) in ppm. 2J[119Sn,1H] and 3J(1H,1H) in Hz are listed in square brackets and parenthesis, respectively.
Multiplicity is given as: s ¼ singlet, bs ¼ broad singlet, d ¼ doublet, t ¼ triplet, m ¼ multiplet.
H
S
5
3
N
2
SH
4
C
1
5'
4'
6
3.2. NMR spectroscopy
1
3.2.1. 1H NMR. The H NMR spectral data of the ligand and complexes are given
in table 3 with their coupling constants. All protons present in the complexes have been
identified at position and number with protons calculated from the incremental method
[30]. The SH peak at 1.58 ppm in the ligand is absent in all the complexes, showing
deprotonation of the ligand during complexation. As reported earlier, when bulky
groups like n-C4H9 or C6H5 are attached in R3SnOOCR’, the carboxylate is
monodentate [31–33]. Probably there is a fast tautomerism in the ligand as shown
below, giving a broad signal at 3.14 ppm.
SH
C
R
S
C
R
H
R
N
S
Sn
R
R
R
N
S
Sn
R
R
R=Bu or Ph
Protons of the dithiolate give a multiplet at 1.39–3.65 ppm which does not show
significant shift upon complexation. In 2 protons of the butyl group appear as multiplet
at 0.88–0.93 ppm. The terminal CH3 group of butyl is a triplet at 0.23 ppm with
3J[1H–1H] coupling of 7.2 Hz. The proton chemical shift of the methyl in 4 attached
2
to the Sn gives a singlet at 0.51 ppm. The J[119Sn–1H] coupling constant value for this
complex is 82 Hz, in the range expected for the five-coordinate tin atom and consistent
with the C–Sn–C angle of 126.5ꢁ.
3.2.2. 13C NMR. 13C and 119Sn NMR spectral data of the complexes are listed in
table 4. The assignment of 13C signals are made by comparison with related compounds
from the incremental method [30]. The 13C NMR chemical shifts due to phenyl attached
to Sn were observed at positions comparable to related compounds [34].

Cyclohexylcarbamodithioic acid
581
Table 4. 13C and 119Sn NMR dataa–c of cyclohexylcarbamodithioic acid and its organotin(IV) complexes.
Chemical shift (ppm)
Carbon
HL
1
2
3
4
5
6
1
3
4,40
5,50
6
211.7
51.4
59.7
24.7
32.0
197.6
51.2
59.7
24.6
32.2
195.8
51.5
59.8
24.2
32.1
195.7
51.6
59.6
24.8
32.7
195.5
51.2
59.7
24.3
32.5
198.9
51.1
59.6
24.9
32.8
195.4
51.9
59.5
24.6
32.3
a(1) Sn–CH3Cl, 10.5; ꢁ 119Sn ¼ –336.2; (2) Sn–CH2CH2CH2CH3Cl, (C–ꢂ) 22.78 1J[341.0], (C–ꢃ) 28.69, (C–ꢄ) 27.08, (C–ꢁ)
13.70; ꢁ 119Sn ¼ –129.4; (3) Sn–CH3, 2.2 1J[395.6]; ꢁ 119Sn ¼ –201.2; (4) Sn–CH3, (Cꢀꢂ) –2.0 1J[571]; (5) Sn–CH2CH2CH2CH3,
(Cꢀꢂ) 22.6 1J[578.6], (Cꢀꢃ) 28.7 2J[34.29], (C–ꢄ) 27.6 3J[87.2], (Cꢀꢁ) 14.2; (6) Sn–C6H5, (C–ꢂ) 136.75, (C–ꢃ) 129.11, (C–ꢄ)
128.52, (C–ꢁ) 128.11; ꢁ 119Sn ¼ –80.0.
bChemical shifts (ꢁ) in ppm. nJ[119Sn,13C] in Hz is listed in parenthesis.
H
S
5
3
N
2
SH
4
C
1
5'
4'
6
Table 5. C–Sn–C angles (ꢁ) calculated from NMR.
Compound
number
C–Sn–C angles (ꢁ)
1J[119Sn–13C] (Hz)
2J[119Sn–1H] (Hz)
1J
2J
2
4
5
341.0
571.0
578.0
–
82
–
106.6
126.5
126.8
127.5
The carbon position of C¼S resonance shifted upfield upon complexation, attributed
to a lowering of C¼S bond order upon coordination and a shift of N!C electron
density producing a partial double bond character in the C–N bond.
To gain further information regarding possible coordination geometries in solution,
2
1J[119Sn–13C] and J[119Sn–1H] coupling constants examined as C–Sn–C bond angles
can be determined [35, 36]. The C–Sn–C angles (ꢁ) based on NMR parameters for the
complexes are given in table 5. The geometric data calculated (table 5) are consistent
with five- and six-coordinate geometry [37]. In triorganotin(IV) complexes, 119Sn
chemical shifts lie in the tetrahedral environment whereas the diorganotin(IV)
compounds show higher coordination, probably five or six.
3.3. Antibacterial activity
Antibacterial activities of ligand and complexes were determined using 1 mg mLꢀ1
DMSO solutions by the disc diffusion method [20, 21]. The inhibition zone (IZ)
diameters were measured in mm.
HL and organotin complexes were tested for in vitro antibacterial activity using
two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two
Gram-negative bacteria (Escherichia coli and Pasteurella multocida). The results were

582
S. Jabbar et al.
Table 6. Antibacterial activitiesa–d of cyclohexylcarbamodithioic acid and its
organotin(IV) complexes.
Bacterial IZ (mm)
Compound
number
B. subtilis
Mean ꢄ SD
P. multocida
Mean ꢄ SD
S. aureus
Mean ꢄ SD
E. coli
Mean ꢄ SD
HL
1
2
3
4
6.0c ꢄ 0.5
5.0c ꢄ 0.4
8.5b ꢄ 0.9
9.5b ꢄ 0.6
7.0b ꢄ 0.5
12b ꢄ 1
7.0c ꢄ 0.6
4.0c ꢄ 0.8
13b ꢄ 1
9b ꢄ 1
12b ꢄ 1
13b ꢄ 1
14.5b ꢄ 0.7
14.5b ꢄ 0.9
14b ꢄ 1
12.0b ꢄ 0.5
12.5b ꢄ 0.8
6b ꢄ 1
24a,b ꢄ 1
11b ꢄ 1
5
14.5b ꢄ 0.5
10b,c ꢄ 1
26a ꢄ 1
7.5b ꢄ 0.4
12a ꢄ 1
13.0b ꢄ 0.6
11a,b ꢄ 1
26a ꢄ 2
10.0b ꢄ 0.8
9.5c ꢄ 0.7
17a ꢄ 2
6
Standard
19a ꢄ 1
aConcentration ¼ 1 mg mLꢀ1 in DMSO.
bStandard ¼ Rifampicin.
c0 ¼ No activity, 5–10 ¼activity present, 10–20 ¼ moderate activity, 20–30 ¼ strong activity.
dAntibacterial values are mean ꢄ SD of three samples analyzed individually in triplicate at
p 5 0.05.
obtained as IZ diameters and compared against the results of rifampicin (positive
control).
The activities of the complexes were less than the standard drug, but higher than the
ligand [26]. Complexes 1–5 show moderate activity against all bacterial strains but
relatively high against Gram-positive bacteria, B. subtilis. This can be attributed to the
difference in the structure of the cell walls. The walls of Gram (ꢀ) cells are more
complex than those of Gram (þ) cells. The lipopolysaccharide forms an outer-lipid
membrane and contributes to antigenic specificity for the Gram (ꢀ) cells. The results
obtained (IZ) are summarized in table 6.
3.4. Antifungal activity
Many organotin compounds are antifungal agents. So HL and compounds were also
tested for antifungal activities against Aspergillus niger, Aspergillus flavus, Alternaria
alternata, and Rhizopus solani. Fluconazole (positive control) was used as standard drug
to calculate the growth IZs of ligand and complexes [38]. The result shows that
coordination of tin causes higher activity of complexes than ligand.
The complexes were more potent inhibitors of fungal growth as compared to
bacterial culture. This may be due to the antifungal nature of sulfur present in the
complexes [39]. The antifungal activity of the complexes against A. niger was
comparable to that of the standard drug. Thus, further studies of these complexes as
fungicides could lead to more interesting results. The IZ diameters of antifungal activity
are given in table 7.
3.5. Minimum inhibitory concentration
The MICs of ligand and complexes were determined by the modified resazurin assay
utilizing microtiter-plates [24]. Resazurin is an oxidation–reduction indicator used
for evaluation of cell growth, particularly in various cytotoxicity assays. It is a blue

Cyclohexylcarbamodithioic acid
583
Table 7. Antifungal activitiesa–d of cyclohexylcarbamodithioic acid and its
organotin(IV) complexes.
Fungal IZ (mm)
Compound
number
A. alternate
Mean ꢄ SD
A. niger
Mean ꢄ SD
R. solani
Mean ꢄ SD
A. flavus
Mean ꢄ SD
HL
1
2
3
4
4.0c ꢄ 0.3
7.0c ꢄ 0.8
13a,b ꢄ 1
10a,b ꢄ 1
11.5a,b ꢄ 0.4
12a,b ꢄ 1
19a ꢄ 1
8.0c ꢄ 0.9
12b ꢄ 1
12b ꢄ 1
22a ꢄ 1
10b ꢄ 1
21b ꢄ 2
15a,b ꢄ 1
24a ꢄ 2
5.0c ꢄ 0.4
9b ꢄ 0.8
9b ꢄ 1
13b ꢄ 1
16a,b ꢄ 1
8.5b ꢄ 0.5
14b ꢄ 1
11a,b ꢄ 0.5
11a,b ꢄ 1
12a,b ꢄ 1
9.5b ꢄ 0.7
13a ꢄ 1
5
11b ꢄ 1
6
Standard
13a,b ꢄ 1
12a,b ꢄ 1
14a ꢄ 1
18a ꢄ 2
aConcentration ¼ 1 mg mLꢀ1 in DMSO; bStandard ¼ Fluconazole; c0 ¼ no activity, 5–10 ¼activity
present, 10–20 ¼ moderate activity, 20–30 ¼ strong activity; dAntifungal values are mean ꢄ SD of
three samples analyzed individually in triplicate at p 5 0.05.
Table 8. MICsa–c of cyclohexylcarbamodithioic acid and its organotin(IV) complexes against selected
fungal strains.
Compound
number
A. alternate
Mean ꢄ SD (mg mLꢀ1
A. niger
Mean ꢄ SD (mg mLꢀ1
R. solani
Mean ꢄ SD (mg mLꢀ1
A. flavus
Mean ꢄ SD (mg mLꢀ1
)
)
)
)
HL
1
2
3
4
3000c ꢄ 1
375b ꢄ 1
187a,b ꢄ 1
750b ꢄ 1
375b ꢄ 1
750b ꢄ 1
750b ꢄ 1
187a ꢄ 1
750c ꢄ 1
187b ꢄ 1
375b ꢄ 1
375b ꢄ 1
750b ꢄ 1
187b ꢄ 1
375b ꢄ 1
93a ꢄ 1
1500c ꢄ 1
750b ꢄ 1
750b ꢄ 1
187b ꢄ 1
187a ꢄ 1
375a ꢄ 1
187a ꢄ 1
375b ꢄ 1
3000c ꢄ 1
750b ꢄ 1
1500b ꢄ 1
750b ꢄ 1
750b ꢄ 1
750b ꢄ 1
750b ꢄ 1
46a ꢄ 1
5
6
Standard
aConcentration ¼ 6 mg mLꢀ1 in DMSO; bStandard ¼ Fluconazole; cMIC values are mean ꢄ SD of three samples analyzed
individually in triplicate at p 5 0.05.
non-fluorescent and non-toxic dye that becomes pink and fluorescent when reduced
to resorufin by oxidoreductase within viable cells. The effectiveness of this modified
resazurin assay has been demonstrated with ligand and complexes.
Rifampicin was used as a standard drug for bacterial strains and fluconazole was
used as antifungal standard drug. The complexes show higher MIC values than
standards but lower than ligand. For antifungal activity the minimum value of MIC of
5 was against A. niger (187 mg mLꢀ1) and maximum was against A. flavus and R. solani
(750 mg mLꢀ1) as shown in table 8. Similarly maximum MIC of 5 was against S. aureus
(1250 mg mLꢀ1) and minimum against B. subtilis (156 mg mLꢀ1) for bacterial strains
which show higher activity against B. subtilis (table 9). The MIC results agree with
antibacterial and antifungal activity results.
3.6. Antioxidant activity
3.6.1. DPPH radical scavenging assay. Antioxidants are substances or nutrients
which can prevent or slow oxidative damage to our body. Health problems such as

584
S. Jabbar et al.
Table 9. MICsa–c of cyclohexylcarbamodithioic acid and its organotin(IV) complexes against selected
bacterial strains.
Compound
number
B. subtilis
Mean ꢄ SD (mg mLꢀ1
P. multocida
Mean ꢄ SD (mg mLꢀ1
S. aureus
Mean ꢄ SD (mg mLꢀ1
E. coli
Mean ꢄ SD (mg mLꢀ1
)
)
)
)
HL
1
2
3
4
625b ꢄ 1
156b ꢄ 1
312b ꢄ 1
78b ꢄ 1
1250c ꢄ 1
312b ꢄ 1
625b ꢄ 1
1250b ꢄ 1
312b ꢄ 1
156a ꢄ 1
156a,b ꢄ 1
156a ꢄ 1
625c ꢄ 1
312b ꢄ 1
156b ꢄ 1
156b ꢄ 1
156b ꢄ 1
1250c ꢄ 1
312b ꢄ 1
39a ꢄ 1
2500b ꢄ 1
625b ꢄ 1
625b ꢄ 1
312b ꢄ 1
1250b ꢄ 1
312b ꢄ 1
312b,c ꢄ 1
78a ꢄ 1
625b ꢄ 1
312b ꢄ 1
1250c ꢄ 1
39a ꢄ 1
5
6
Standard
aConcentration ¼ 5 mg mLꢀ1 in DMSO; bStandard ¼ Rifampicin; cMIC values are mean ꢄ SD of three samples analyzed
individually in triplicate at p 5 0.05.
Table 10. IC50 of cyclohexylcarbamodithioic acid and its organotin(IV)
complexes.a,b
Compound number
IC50 Mean ꢄ SD (mg mLꢀ1
)
HL
1
2
3
4
76ꢄ 2
48b ꢄ 2
48b ꢄ 2
44a ꢄ 2
49b ꢄ 2
75b ꢄ 2
49b ꢄ 2
44a ꢄ 2
5
6
Standard
aStandard ¼ butylated hydroxytoluene.
bIC50 values are mean ꢄ SD of three samples analyzed individually in triplicate
at p 5 0.05.
heart disease, diabetes, cancer, are all contributed by oxidative damage. Antioxidant
activities or free radical scavenging activities of complexes and ligand were determined
using the free radical, 2,2-diphenyl-1-picrylhydrazyl (DPPH.). In its radical form
DPPH. has an absorption at 517 nm with deep violet color which changes to pale yellow
upon reduction by an antiradical compound. The free radical scavenging capacity
increased with increasing concentration.
The % inhibition values and hence IC50 values of complexes and ligand were
calculated and results were compared with the antioxidant butylated hydroxytoluene
(BHT) (44 ꢄ 2 mg mLꢀ1). The IC50 (the sample concentration providing 50% inhibition)
values were used as end point to investigate the antioxidant activity, i.e., the greater the
IC50 value, the lower will be the antioxidant activity [40]. The results obtained (table 10)
were significant with R2 ¼ 0.9099 and p 5 0.05.
The results show that the ligand itself acts as an antioxidant agent (with IC50 value
of 76 ꢄ 2 mg mLꢀ1) but to lower extent than BHT (with IC50 value of 44 ꢄ 2 mg mLꢀ1).
The activity of the ligand was increased on coordination with tin due to the presence
of the proton donor capacity of the ligand [41].
3.6.2. Hemolytic activity. The in vitro hemolytic activities (or cytotoxicity assay)
of HL and compounds were performed to check their effect on human blood by the

Cyclohexylcarbamodithioic acid
585
Table 11. Cytotoxicities of cyclohexylcarbamo-
dithioic acid and its organotin(IV) complexes.a–c
% Hemolysis
Mean ꢄ SD (%)
Compound No.
HL
1
2
3
4
5
6
PBS
6.8b,c ꢄ 0.1
7.1b ꢄ 0.1
7.3b ꢄ 0.1
8.7b ꢄ 0.5
8.3b ꢄ 0.1
7b,c ꢄ 1
8.7b ꢄ 0.1
0.01c ꢄ 0.0
99a ꢄ 1
Triton X-100
aPBS ¼ Negative control standard drug.
bTriton X-100 ¼ positive control standard drug.
cCytotoxicity activities are mean ꢄ SD of three samples
analyzed individually in triplicate at p 5 0.05.
hemolytic method [25]. The results were obtained by comparison with a positive control
(Triton X-100) and a negative control (PBS). The results are given in table 11. The mean
values obtained are 7.1 ꢄ 0.1% (1), 6.8 ꢄ 0.1% (ligand), 0.01 ꢄ 0.0% (negative control),
and 99 ꢄ 1% (positive control).
The hemolytic activities of the complexes were higher than that of the ligand
(6.8 ꢄ 0.1%) and close to PBS (negative control), but not to Triton X-100 (positive
control). Hence the toxicity of the complexes was very low to human blood. By
comparing these results with antimicrobial and antioxidant activities, it can be concluded
that the reported complexes (1 mg mLꢀ1) show poor hemolytic activity, but good
antimicrobial and antioxidant activities, and could be further investigated as medicinal
agents against different microorganisms with minor side effect.
3.6.3. Mutagenic activity. In the Ames test [27], mutagenic potential of 6 was
evaluated by using Salmonella typhimurium, TA 98 and TA 100. Experiments were
performed in triplicate for both complexes. Negative and positive controls were also
carried out simultaneously. For TA-98, K2Cr2O7, and TA-100, sodium azide (NaN3)
(10–35 mg/plate) were used as positive controls in experiments along with known
mutagens like MNNG (12 mg/plate) and benzo (a) pyrene (35 mg/plate). Distilled water
served as negative control and DMSO as vehicle control. In the Ames test, with various
concentrations of synthesized compounds (10,000, 1000, and 500 mg/plate), the
mutation frequencies did not change significantly when compared to the positive
control.
Only a few revertant colonies were observed for the complex (table 12), probably due
to the toxic or inhibitory effect of the complex which may inhibit the growth of strains
TA-100 and TA-98. It may also be due to the antibacterial property of the reported
complex. This result is consistent with an earlier report [42] that complexation with
organotin compounds led to complexes devoid of mutagenicity. This behavior suggests
that structural factors imposed by the organotin moieties may be responsible for the
absence of activity.

586
Table 12. Mutagenic activity of 6 by plate incorporation assay.
Hisþ revertants/plate (Number of colonies)
TA98 TA100
S. Jabbar et al.
Compound
number
Amount tested
(mL/plate)
1
0
2
Mean
11
M.I
0.21
1
2
6
Mean
15
MI
6
100
22
12
0.27
Negative control
Mean
Mean
Distilled water
DMSO
100
100
34
0
68
13
50
32
51
21
55
5
35
12
71
14
54
10
Positive control
NaN3
K2Cr2O7
MNNG
B(a)P
10
10
3
10
5
0
38
35
84
0
0
66
42
95
0
0
66
81
110
0
53
0
58
0
66
0
58
0
75
0
115
0
B(a)P
84
65
87
NaN3 ¼ 35 mg/plate; K2Cr2O7 ¼ 35 mg/plate; N-methyl-N’-nitro-N-nitrosoguanidine (MNNG) ¼ 12 mg/plate; Benzo[a]
pyrene[B(a)P] ¼ 35 mg/plate; Test compound ¼ 0.01 gmmLꢀ1of DMSO (500 and 1000 mg/plate).
ꢁ
˚
Table 13. Selected bond lengths (A) and angles ( ) for 1, 3, and 4.
Compound 1
S2–C3–1.70
S2–Sn1–2.74
C25–Sn1–2.12
S2–Sn1–Cl24
C3–S2–Sn1
S2–C3–N5
C3–S4
1.74
2.40
2.12
93.4
115.4
119.4
Cl24–Sn1
C29–Sn1
S2–Sn1–C25
S2–C3–S4
S4–C3–N5
154.9
88.1
125.2
Compound 3
S2–C3–1.74
S2–Sn1–2.57
C28–Sn1–2.13
S2–Sn1–C24
S2–Sn1–S4
C3–S4
C24–Sn1
Sn1–S4
S2–Sn1–C28
S2–Sn1–S32
C24–Sn1–C28
1.70
2.13
2.84
107.7
145.9
133.8
107.6
65.2
80.9
S2–Sn1–S34
Compound 4
Sn1–S4–2.76
S2–Sn1–2.67
C28–Sn1–2.13
S2–Sn1–C24
S2–Sn1–C32
C24–Sn1–C28
C3–S4
C24–Sn1
C32–Sn1
S2–Sn1–C28
S2–Sn1–S4
C24–Sn1–C32
1.70
2.13
2.14
118.7
64.3
104.6
119.5
87.8
114.7
3.7. Structure–activity relationship
The different methods by which complexes can exert their action as antimicrobial
agents can include the effect of resonating structure such as potentially reactive
groupings, the introduction of a lipophilic substituent, either aryl or alkyl group, or
the hydrolysis of amine or reactive halogens to form microbial inhibitor growth
compounds [40].

Cyclohexylcarbamodithioic acid
587
Figure 1. Optimized structures of 1, 3, and 4.

588
S. Jabbar et al.
Degradative enzymes produced by the microorganism are important in host infection,
food deterioration, and breakdown of organic matter. Since the organotin(IV) complexes
inhibit the growth of organisms, it is assumed that the production of the enzymes is
being affected; hence the organisms are unable to utilize food and, consequently, growth
ceases.
Although, it is difficult to make out an exact structure–activity relationship between
the microbial activity and the structure of complexes, chelation as well as addition of
a substrate enhances the activities of the complexes. The variation in the toxicity
of different antibacterial agents against different organisms depends either on the
impermeability of the cell or difference in ribosomes to the antimicrobial agent.
Though the results suggest that the ligand also has some toxicity, the complexes
inhibit the growth of organisms to a greater extent. Further, the greater activity of the
complexes can also be explained on the basis of their higher solubility [41].
3.8. Semi-empirical study
In 1, the ligand binds bidentate to two Sn(IV) atoms. The two-methyl groups, Cl and
the dithio group are arranged in a distorted trigonal bipyramid. The Sn–S bond
˚
distances are 2.63 and 2.74 A. The Sn–C bond lengths are 2.12, 2.12 A, Sn–Cl distance
˚
˚
˚
is 2.40 A, and the C–S bond distances are 1.74 and 1.70 A. The Sn–S–C bond angles are
88.1ꢁ and 91.1ꢁ and S–C–S bond angle is 115.4ꢁ, while the S–Sn–S angle is 65.5ꢁ.
Two ligands bind bidentate to Sn(IV) in 3. The two-methyl groups and the two dithio
groups are arranged in a distorted octahedron. The Sn–S bond distances are 2.57, 2.84,
˚
˚
2.57, and 2.84 A. The Sn–C bond lengths are 2.13 and 2.13 A and the C–S bond
ꢁ
ꢁ
˚
distances are 1.74, 1.70, 1.75, and 1.69 A. The Sn–S–C bond angles are 85.0 , 93.2 ,
85.0ꢁ, and 93.3ꢁ and S–C–S bond angles are 116.6ꢁ and 116.7ꢁ, while the S–Sn–S angles
are 65.2ꢁ and 65.1ꢁ.
In 4, the ligand binds bidentate to Sn(IV). The three-methyl groups and the dithio
group form a distorted trigonal bipyramid. The Sn–S bond distances are 2.67 and
˚
˚
2.76 A. The Sn–C bond lengths are 2.13, 2.13, and 2.14 A and the C–S bond distances
are 1.73 and 1.70. The Sn–S–C bond angles are 89.2ꢁ and 91.8ꢁ and S–C–S bond angle is
114.7ꢁ, while the S–Sn–S angle is 64.3ꢁ.
All bond lengths and angles are comparable to literature values [43]. The selected
bond lengths and angles of the optimized structures are tabulated in table 13. The
optimized structures are given in figure 1.
4. Conclusion
FT-IR data of the complexes clearly demonstrate that the organotin(IV) moiety reacts
with [S,S] of the ligand in a bidentate manner. NMR data show tetrahedral geometry in
solution. The antimicrobial assay of ligand and complexes against different bacterial
and fungal strains show that the complexes are more active than the ligand;
mutagenicity results show that the antibacterial property of 6 is coupled with lack of
mutagenicity. The complexes also show higher antioxidant activities than the ligand.
The hemolytic activities of the complexes and ligand were very low compared to the

Cyclohexylcarbamodithioic acid
589
free ligand. By comparing the results of mutagenic and hemolytic activities with the
results of antimicrobial and antioxidant activities, it can be predicted that the complexes
have large inhibitory effect and might indeed be potential antimicrobial agents and be
used in biomedical and pharmaceutical fields.
Acknowledgments
SA and SS are grateful to the Pakistan Science Foundation for support under the
Project No. PSF/Res/P-GCU/Chem(436). SKS and KQ thank the Head, Applied
Science and Dean FET, MITS for encouragement and support.
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