Synthesis, characterization, HOMO-LUMO study, and antimicrobial activity of organotin(IV) complexes of 4-piperidine carboxamide and its Schiff base

Article abstract of DOI:10.1080/00958972.2013.869584

A series of organotin(IV) complexes has been synthesized by reacting 4-piperidine carboxamide with CS₂ and R₂SnCl ₂/R₃SnCl in 1: 1 M/L ratio at room temperature. The synthesized complexes were further treated with benzaldehyde to synthesize Schiff bases under stirring. All the complexes were characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR. FT-IR and semi-empirical study confirm the bidentate nature of ligand. The complexes exhibit four-coordinate geometry in solution. Thermodynamic parameters and molecular descriptors were calculated by using semi-empirical PM3 method. HOMO-LUMO calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic attack when compared with triorganotin complexes. Negative heats of formation at 298 K demonstrate that 1, 4, and 7 are thermodynamically stable. The antimicrobial results have shown that complexes containing Schiff base exhibit significantly better activity compared to complexes with carboxamide derivatives. 2014

Full text of DOI:10.1080/00958972.2013.869584

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Synthesis, characterization, HOMO-LUMO study and
antimicrobial activity of organotin(IV) complexes of 4-
piperidine carboxamide and its Schiff base
Muhammad Rizwana, Saqib Alib, Saira Shahzadia, Saroj K. Sharmac, Kushal Qanungoc,
Muhammad Shahidd & Sohail Mahmoode
a Department of Chemistry, GC University, Faisalabad, Pakistan
b Department of Chemistry, Quaid-i-Azam University, Islamabad-45320, Pakistan
c Department of App. Sci. and Hum., Faculty of Engg. and Tech., Mody Institute of
Technology and Science (Deemed University), Lakshmangargh-332311, Dist Sikar, Raj., India
d Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad, Pakistan
e Department of Chemistry, Islamabad College for Boys (ICB), G-6/3, Islamabad, Pakistan
Accepted author version posted online: 28 Nov 2013.Published online: 28 Nov 2013.
To cite this article: Journal of Coordination Chemistry (2013): Synthesis, characterization, HOMO-LUMO study and
antimicrobial activity of organotin(IV) complexes of 4-piperidine carboxamide and its Schiff base, Journal of Coordination
Chemistry, DOI: 10.1080/00958972.2013.869584
To link to this article: http://dx.doi.org/10.1080/00958972.2013.869584
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Synthesis, characterization, HOMO-LUMO study and antimicrobial
activity of organotin(IV) complexes of 4-piperidine carboxamide and its
Schiff base
MUHAMMAD RIZWANa, SAQIB ALI*b, SAIRA SHAHZADI*a, SAROJ K. SHARMAc, KUSHAL
QANUNGOc, MUHAMMAD SHAHIDd and SOHAIL MAHMOODe
aDepartment of Chemistry, GC University, Faisalabad, Pakistan
bDepartment of Chemistry, Quaid-i-Azam University, Islamabad-45320, Pakistan
cDepartment of App. Sci. and Hum., Faculty of Engg. and Tech., Mody Institute of Technology and Science
(Deemed University), Lakshmangargh-332311, Dist Sikar, Raj., India
dDepartment of Chemistry and Biochemistry, University of Agriculture, Faisalabad, Pakistan
eDepartment of Chemistry, Islamabad College for Boys (ICB), G-6/3, Islamabad, Pakistan
A series of organotin(IV) complexes has been synthesized by reacting 4-piperidine
carboxamide with CS2 and R2SnCl2/R3SnCl in 1:1 M/L ratio at room temperature. The
synthesized complexes were further treated with benzaldehyde to synthesize Schiff bases
1
under stirring. All the complexes were characterized by elemental analysis, FT-IR, H and
13C-NMR. FT-IR and semi-empirical study confirm the bidentate nature of ligand. The
complexes exhibit four-coordinate geometry in solution. Thermodynamic parameters and
molecular descriptors were calculated by using semi-empirical PM3 method. HOMO-LUMO
calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic
attack as compared to triorganotin complexes. Negative heats of formation at 298K
demonstrate that 1, 4 and 7 are thermodynamically stable. The antimicrobial results have
shown that complexes containing Schiff base exhibit significantly better activity compared to
complexes with carboxamide derivatives.
Keywords: 4-Piperidine carboxamide; Schiff base; Organotin complexes; Spectroscopic
studies; Semi-empirical study; HOMO-LUMO calculations; Biological activity
1. Introduction
Organotin(IV) complexes are of interest because of their biomedical and commercial
applications [1]. Several organotin complexes are effective as antifouling, antimicrobial [2],
and antiviral agents. Applications of metal complexes in the treatment of numerous human
diseases is a vigorously expanding area in biomedical and inorganic chemistry [3, 4].
There has been interest in coordination chemistry of Schiff bases because of ease of
syntheses of various metal complexes [5, 6] and stabilization in various oxidation states.
*Corresponding authors. Email: drsa54@yahoo.com (S.A.); sairashahzadi@hotmail.com (S.S.)
1

Schiff-base complexes have been used as models for biological systems [7, 8]. In addition to
anti-tumor activities, organotin(IV) complexes with Schiff bases present an interesting
variety of structural possibilities [9].
As an extension of our previous work with Schiff bases [10-12], the present studies
have been undertaken to investigate organotin(IV) derivatives of 4-piperidine carboxamide
and its Schiff base to compare the biological activities.
2. Experimental
2.1. Chemicals and instrumentation
All reagents and solvents were purchased from Sigma, Aldrich and Merck. The solvents were
dried [13] prior to use. The melting points of complexes were determined by electrothermal
melting point apparatus using open capillaries (Stuart-SMP, USA). Elemental analyses were
carried out on a CHNS elemental analyzer Leco (USA). Infrared spectra were recorded as
KBr/CsBr discs using a Perkin Elmer spectrophotometer from 4000–250 cm−1. 1H and 13C
NMR spectra were recorded on a Bruker 300 MHz FT-NMR spectrometer using CDCl3 as an
internal standard.
The molecules were modeled by MOPAC 2007 program [14] in the gas phase using
PM3 method [15], based on the premise that atoms prefer an arrangement which has the
minimum energy and hence most stable. Selected parts of the complexes not containing tin
were pre-optimized using molecular mechanics methods. Several cycles of energy
minimization had to be carried out for each molecule. The structures were optimized by
Eigen Vector. The root mean square gradient for molecules was less than one. Self consistent
field was attained in each case. Absences of imaginary frequencies were checked.
2.2. General procedure for synthesis of organotin(IV) complexes
Step-I
4-Piperidine carboxamide (1 mmol) was dissolved in ethanol (20 ml) in a round bottom flask
(250 ml) with continuous stirring and then CS2 (1 mmol) was added dropwise. The reaction
mixture was stirred at room temperature for 0.5 h. Then R2SnCl2/R3SnCl (1 mmol) was added
as solid in portions in the above reaction mixture and stirred continuously for 7 h. Solvent
was evaporated and the solid product obtained was recrystallized in ethanol:pet.ether (1:1).

Step-II
The product obtained in step-I (1 mmol) was dissolved in ethanol (15 ml) with continuous
stirring at room temperature and benzaldehyde (1 mmol) was added dropwise. The reaction
mixture was further stirred for 8 h at room temperature. Solvent was evaporated and the
product obtained was recrystallized in ethanol:pet.ether (1:1).
R
Me
n-Bu
Ph
Compound
1, 4, 7, 10
2, 5, 8, 11
3, 6, 9, 12
3

3. Results and discussion
The synthesized complexes have sharp melting points and are soluble in common organic
solvents. Elemental analysis data reveal that the observed values are in agreement with
calculated values. Physical data are given in table 1.
3.1. Infrared spectroscopy
In order to study the binding mode of the ligand with tin(IV), spectra of the complexes were
compared with that of ligand [16]; data are given in table 2. The disappearance of the S-H
band in spectra of all synthesized complexes confirms the complexation of organotin(IV)
through sulfur. It has been reported [17] that observation of a single υC=S at 1000 cm-1 is
indicative of dithiocarbamate groups bonded symmetrically or bidentate. A strong ν(C-S) is
at 1004-1056 cm-1, while ν(C=S) is at lower frequency, 939-993 cm-1.
Schiff base formation was confirmed due to the occurrence of νC=N bands at 1614-
1697 cm-1 in 7-12. The spectral band due to -NH at 3248-3296 cm-1 in ligand and 1-6
illustrates that –NH does not coordinate [18] and disappearance of this band in 7-12 confirms
formation of Schiff base.
New bands at 528-563 cm-1, 461-492 cm-1 and 221-242 cm-1 are assigned to ν(Sn-C),
ν(Sn-S) and ν(Sn-Cl), respectively [19, 20]; ν(Sn-C) band appears at 263, 254, 251 and 261
cm-1 for 3, 6, 9 and 12, respectively, which are di- and triphenyltin derivatives.
3.2. 1H NMR Spectroscopy
1H NMR spectral data of the ligand and 1-12 are given in tables 3 and 4 along with their
coupling values. The absence of the −SH proton resonance in the complexes confirms
deprotonation. All the protons present in 1-12 have been identified in position and number
with the protons calculated from the incremental method [21]. The NH2 protons are sharp
singlet at 8.73 in HL and do not show any shift in 1-6, confirming that this group does not
participate in complexation. Disappearance of this signal in spectra of 7-12 confirms reaction
of NH2 with benzaldehyde to yield the Schiff base. The CH3 protons in 1 and 7 are singlets at
2
1.13 and -0.01 ppm with tin satellites having J[119Sn–1H] = 96 and 98 Hz, respectively,
supporting five-coordinate tin in solution [17].
In 2 and 8, the methylene protons of butyl are multiplets at 1.26-1.87 and 0.56-
0.90 ppm. The terminal CH3 group of butyl gives triplets at 0.87 and 0.20 ppm with
4

3J[1H−1H] of 7.2 Hz for 2 and 8, respectively. The methyls in 4 and 10 attached to Sn give
singlets at 0.39 and 0.50 ppm.
In triphenyltin(IV) derivatives, the phenyl protons consisted of two groups of peaks.
The ortho protons were observed at 6.86-7.30 and 6.98-7.42 ppm and those for the meta and
para protons (6.69-6.92 and 6.82-6.95 ppm) for 6 and 12.
3.3. 13C NMR Spectroscopy
Tables 5 and 6 list the 13C chemical shifts and tin-carbon coupling constants for 1-12. In 7-12,
the chemical shift of C-1 attached with sulfur (-CSS) was at 194.4-194.6 ppm [22].
The C=O in 1-6 give signal at 175.56-175.98 ppm, upfield in 7-12 due to
condensation of NH2 with benzaldehyde to 169.8-169.8 ppm.
1
The J(119Sn-13C) for 4, 6, 8, 10 and 11 are 395.6, 638.1, 558.3, 378.6 and 578.6 Hz,
respectively, indicative of four-coordinate geometry [23] in solution.
In 1 and 7, signals at 28.5 ppm and 28.7 ppm were due to methyl bound to Sn. In 12,
phenyl carbon signals were observed at 128.7-137.2 ppm [24, 25].
3.4. Semi-empirical study
In the geometry optimized structures, one sulfur of the ligand bonds bidentate to tin. The
other positions are occupied by methyl or phenyl groups. Selected bond angles (°) and bond
lengths (Å) are given in Supplementary Material and are typical [26]. The piperidine
molecule adopts a chair like configuration in all the complexes.
Computed negative heats of formation indicate that 1, 4 and 7 are thermodynamically
stable (Supplementary Material). The calculated HOMO and LUMO of 1, 3, 4, 6, 7, 9, 10 and
12 are shown in figure 1 and Supplementary Material. The HOMO is primarily located on
sulfur and chloride, while the LUMO is located on Sn, which indicates that Sn is highly
susceptible to nucleophilic attack. The calculated HOMO and LUMO energies are shown in
Supplementary Material. A large HOMO-LUMO gap indicates stable molecule with low
chemical reactivity, while a small energy of HOMO is associated with unstable molecule
with high chemical reactivity. Energy of HOMO for 3 and 10 shows that 3 is least stable with
high reactivity while 10 is most stable with less reactivity. The ability of the molecule to
donate electrons, (-Ionisation Potential), ELUMO represents (- Electron Affinity), and
2
electrophilicity values (ω = μ /2η) [27], chemical potential values μ = - (I+A)/2 [28], global
hardness (η = I-A/2) values [29] and global softness values (S=1/2η) [30] have been
5

calculated in each case (Supplementary Material). The presence of a chloride instead of a
methyl or phenyl increases the electrophilic character of the molecule. In other words, the
chlorodiorganotin complexes are more susceptible to nucleophilic attack as compared to
triorganotin complexes. Substituting chloride for methyl/phenyl makes the molecule less hard
due to lower HOMO-LUMO gap.
3.5. Antibacterial activity
The ligand and organotin(IV) complexes were screened for their antibacterial activity against
B. subtilus, P. multocida, S. aureus and E. coli test by the disc diffusion method [31].
Rifampicin was used as positive control to compare its activity with synthesized complexes.
The data in table 7 show the complexes exhibit significant antibacterial activity as compared
to free ligand.
The antibacterial activities of 7-12 containing the Schiff base were better than 1-6,
suggesting the imine group enhances activity of complexes [7, 8]. This may be due to the
greater lipophilic nature of the complexes [32-35]. Comparison of the activities of
synthesized complexes with standard drug and with compounds already reported in literature
[36-45] showed that some complexes are more potent but some are less active than standard
drug against different test microorganisms.
3.6. Antifungal activity
The antifungal activities of organotin(IV) complexes along with the ligand were checked
against selected fungal strains A. niger, A. flavus, G. lucidum and A. alternata. Standard drug
showed highest antifungal activity against all selected fungi. Data are given in table 8. The
results show that 7-12 have better fungicidal activity compared to 1-6 without Schiff base.
The better fungicidal activity is due to formation of Schiff base in 7-12 which enhances the
activity on coordination with tin [46]. Greater fungicidal activity of organotin(lV) complexes
as compared to free ligand may be due to chelation.
4. Conclusion
We have synthesized organotin(IV) complexes with 4-piperidine carboxamide and its Schiff
base with benzaldehyde under stirring. IR and semi-empirical study confirms the bidentate
nature of ligand. Complexes are five-coordinate in the solid state. NMR data reveal four-
coordinate geometry in solution. HOMO-LUMO calculations show that chlorodiorganotin
complexes are more susceptible to nucleophilic attack as compared to triorganotin
6

complexes. Computed negative heat of formation shows that 1, 4 and 7 are
thermodynamically stable. Antimicrobial results reveal that activity is enhanced upon
coordination with tin. The antimicrobial activity further increases upon coordination with
Schiff base. Difference in behavior towards bacterial and fungal strains suggest different
mode of action and activity controlling factors in either case.
Acknowledgements
Pakistan Science Foundation is acknowledged for support under the project No. PSF/Res/P-
GCU/Chem(436). SKS and KQ thanks the Head, App Sci. and Dean FET, MITS for
encouragement and support.
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9

Table 1. Physical data of organotin(IV) complexes.
M. P
Elemental analysis
% C
calcd.
(found)
% H
calcd.
(found)
% N
calcd.
(found)
% S
calcd.
(found)
Complex No.
Molecular formula
M. W
% Yield
(°C)
41.17
(41.14)
27.89
(27.93)
38.20
(38.24)
44.60
(44.55)
32.72
(32.77)
46.20
(46.16)
54.27
(54.31)
40.40
(40.36)
47.21
(47.24)
52.07
(52.12)
44.86
5.92
(5.96)
4.42
(4.40)
6.20
(6.15)
4.14
(4.10)
5.49
(5.42)
7.76
(7.71)
4.74
(4.70)
4.45
(4.41)
5.94
(5.90)
4.20
(4.24)
5.31
13.72
(13.68)
7.23
(7.19)
5.94
(5.90)
5.47
(5.51)
7.63
(7.68)
5.68
(5.71)
5.06
(5.01)
5.89
(5.94)
5.00
(5.04)
4.67
(4.71)
6.15
31.37
(31.32)
16.52
(16.56)
13.58
(13.54)
12.53
(12.57)
17.45
(17.41)
12.99
(13.04)
11.57
(11.52)
13.45
(13.49)
11.44
(11.48)
10.69
(10.63)
14.07
HL
1
C7H12N2OS2
C9H17N2OS2SnCl
C15H29N2OS2SnCl
C19H21N2OS2SnCl
C10H20N2OS2Sn
C19H38N2OS2Sn
C25H26N2OS2Sn
C16H21N2OS2SnCl
C22H33N2OS2SnCl
C26H25N2OS2SnCl
C17H24N2OS2Sn
C26H42N2OS2Sn
C32H30N2OS2Sn
204
387.2
471.2
511.68
367.1
493.1
553.7
475.2
559.2
599.78
455.2
581.4
641.4
214-215
168-170
115-118
182-183
98-100
76
70
74
85
80
80
76
61
63
78
80
77
89
2
3
4
5
110-112
166-167
141-143
122-124
171-172
160-163
102-105
113-115
6
7
8
9
10
11
12
(44.90)
53.72
(53.76)
59.92
(60.06)
(5.35)
7.28
(7.25)
4.71
(4.67)
(6.11)
4.82
(4.86)
4.37
(4.42)
(14.02)
11.02
(11.01)
10.00
(10.05)
10

Table 2. Infrared absorption bands (cm-1) of organotin(IV) complexes.
Complex No.
ν(S-H)
ν(C=S)
ν(C-S)
ν(NH)
ν(C=N)
ν(Sn-C)
ν(Sn-S)
ν(Sn-Cl)
HL
1
2796
997
968
978
952
947
942
993
941
976
972
964
945
939
947
3248
-
-
-
-
242
239
230
-
-
-
1024
1012
1032
1056
1045
1023
1045
1004
1015
1050
1043
1030
3265
-
-
545
544
263
555
535
254
530
536
251
540
528
261
492
472
474
479
472
461
464
469
480
483
469
487
2
3296
3
3285
-
4
-
-
-
-
-
3207
-
5
3271
-
-
6
3290
-
-
7
-
-
-
-
-
-
1685
1697
1626
1690
1614
1650
234
239
221
-
8
9
10
11
12
-
-
-
-
-
11

Table 3. 1H NMR dataa-c of organotin(IV) complexes.
Chemical shift (ppm)
Proton No.
HL
1
2
3
4
5
6
2, 2/
3, 3/
NH2
SH
1.83-1.88m
2.85-2.96m
8.73s
1.82-1.86m
2.82-2.86m
8.74s
1.82-1.87m
2.82-2.87m
8.73s
1.82-1.87m
2.84-2.85m
8.74s
1.82-1.87m
2.82-2.86m
8.74s
1.81-1.87m
2.81-2.85m
8.74s
1.81-1.86m
2.82-2.87m
8.74s
1.62s
-
-
-
-
-
-
0.39s
0.87t(7.2)
6.52-6.83m
6.12-7.50m
0.92t(7.7)
6.69-6.92m
6.86-7.30m
[77.8]
1.13s
[96]
R
-
1.26-1.34m
1.61-1.87m
1.63-1.68m
1.72-1.77m
a Chemical shifts (δ) in ppm. nJ(1H,1H) and nJ[119Sn,1H] in Hz are listed in parenthesis and square brackets, respectively
b Multiplicity is given as, s = singlet, t = triplet, m = multiplet
c
S
R
3
Sn
R
2
C
1
N
O
R'
S
NH2
C
5
3'
4
2'
R/ = R for triorganotin
R/ = Cl for diorganotin
R = Me, n-Bu, Ph
12

Table 4. 1H NMR dataa-c of organotin(IV) complexes.
Chemical shift (ppm)
Proton No.
7
8
9
10
11
12
2,2/
3,3/
4
2.78-2.87m
1.83-1.86m
2.42-2.47m
7.44s
2.77-2.86m
1.82-1.87m
2.41-2.46m
7.43s
2.78-2.87m
1.82-1.86m
2.42-2.46m
7.45s
2.78-2.87m
1.82-1.87m
2.41-2.47m
7.44s
2.78-2.87m
1.83-1.87m
2.43-2.47m
7.44s
2.77-2.86m
1.85-1.86m
2.45-2.46m
7.46s
6
8,12
9,11
10
7.27-7.40m
6.81-6.93m
7.27s
7.26-7.39m
6.80-6.95m
7.28s
7.26-7.40m
6.81-6.94m
7.27s
7.27-7.41m
6.82-6.90m
7.26s
7.27-7.39m
6.82-6.95m
7.27s
7.28-7.40m
6.80-6.95m
7.28s
0.56-0.90m
0.20t(7.2)
6.72-6.87m
6.92-7.52m
0.64-1.1m
0.23t(7.2)
6.82-6.95m
6.98-7.42m
R
-0.01 2J[98]
0.50s 2J[82]
a Chemical shifts (δ) in ppm. nJ(1H,1H) and nJ[119Sn,1H] in Hz are listed in parenthesis and square brackets, respectively
b Multiplicity is given as, s = singlet, m = multiplet
c
S
R
3
Sn
R
R'
C
1
N
2
o
H
C
6
8
S
N
C
5
3'
7
9
2'
4
10
12
11
R/ = R for triorganotin; R/ = Cl for diorganotin
R = Me, n-Bu, Ph
13

Table 5. 13C NMR dataa-c of organotin(IV) complexes.
Chemical shift (ppm)
Carbon No.
HL
1
2
3
4
5
6
1
2, 2/
3, 3/
4
211.6
42.9
195.7
42.8
195.0
42.8
195.5
42.7
195.6
42.8
195.2
42.7
195.4
42.8
28.9
28.5
28.7
28.6
28.6
28.3
28.7
39.8
39.8
39.9
39.8
39.8
39.8
39.8
5
175.7
175.6
175.6
175.5
175.8
175.9
175.6
a Compound 1: Sn-CH3Cl; (C-α) 28.5 1J[299]; Compound 2: Sn-C4H9Cl; (C-α) 28.1 1J[551], (C-β) 27.2 2J[24], (C-γ) 26.5 3J[65], (C-δ) 14.1; Compound 3: Sn-
C6H5Cl, (C−α) 147.3 1J[434], (C−β) 137.8 2J[34], (C-γ) 135.6 3J[43], (C−δ) 129.6; Compound 4: Sn-CH3, (C−α) -2.0 1J[395]; Compound 5: Sn-C4H9; (C-α)
28.8 1J[573], (C-β) 26.80 2J[23], (C-γ) 25.4 3J[65], (C-δ) 14.2; Compound 6: Sn-C6H5, (C−α) 142.1 1J[638], (C−β) 136.0 2J[47.8], (C-γ) 135.9 3J[58], (C−δ)
129.2.
b Chemical shifts (δ) in ppm. nJ[119Sn,13C] in Hz are listed in square brackets
c
S
R
3
Sn
R
2
C
1
N
O
R'
S
NH2
C
5
3'
4
2'
R/ = R for triorganotin
R/ = Cl for diorganotin
R = Me for 1, 3, Bu for 2, 4, Ph for 5
14

Table 6. 13C NMR dataa-c of organotin(IV) complexes.
Chemical shift (ppm)
Carbon No.
7
8
9
10
11
12
1
2,2/
3,3/
4
194.6
43.4
194.4
43.4
194.3
43.4
194.6
43.4
194.5
43.4
194.6
45.4
28.9
28.9
28.9
28.9
28.9
28.9
39.0
39.0
39.0
39.0
39.0
39.0
5
169.8
161.2
131.5
129.4
128.2
136.0
169.8
161.1
131.5
129.3
128.2
136.0
169.8
161.2
131.4
129.2
128.2
136.0
169.8
161.1
131.5
129.5
128.2
136.0
169.8
161.1
131.5
129.5
128.2
136.0
169.8
161.1
136.5
129.2
128.2
136.0
6
7
8,12
9,11
10
a Compound 7: Sn-CH3Cl; (C-α) 28.7 1J[297]; Compound 8: Sn-CH2CH2CH2CH3Cl, (C−α) 20.9 1J[558], (C−β) 28.6 2J[33], (C-γ) 27.6 3J[86], (C−δ) 14.0;
Compound 9: Sn-C6H5Cl, (C-α) 137.0 1J[438], (C-β) 129.2 2J[36], (C-γ) 136.2 3J[46], (C-δ) 128.2; Compound 10: Sn-CH3, 2.2 1J[378]; Compound 11: Sn-
CH2CH2CH2CH3, (C−α) 22.6 1J[578], (C−β) 28.7 2J[34], (C-γ) 27.6 3J[87], (C−δ) 14.2; Compound 12: Sn-C6H5, (C-α) 137.2 1J[642], (C-β) 129.8 2J[49],
(C-γ) 136.5 3J[62], (C-δ) 128.7
b Chemical shifts (δ) in ppm. nJ[119Sn,13C] in Hz are listed in square brackets
c
S
R
R
R
3
S
n
C
1
N
2
o
H
C
6
'
8
S
N
C
5
3 '
7
9
2 '
4
1 0
1 2
1 1
R/ = R for triorganotin
R/ = Cl for diorganotin
15

Table 7. Antibacterial activitya-c of organotin(IV) complexes.
Zone of inhibition (mm)
Complex No.
B. subtilus
S. aureus
P. multocida
E. coli
17f
19.5e 0.9
HL
18.5e 0.9
22.0d 0.00
22.5d 0.9
24.0cd 0.00
23.3cd 0.8
26.0ab 0.9
24.0cd 0.00
24.0cd 1.4
26.0b 0.00
14.5f 0.9
20.5e 0.9
21.5de 0.5
21.7de 0.4
25.2bc 0.8
23.5cd 0.8
1
1
21de
1
2
22.0cd 0.00
24.6bc 0.8
20.0e 0.00
3
22cd
1
4
23cd
21de
1
1
21.3de 0.8
26.0ab 0.00
5
26b
1
6
24.7bc 0.8
24.0bcd 0.00
25.3bc 0.8
25.3bc 0.8
24.0c 0.00
22cde
23.5bcd 0.5
24bc
1
7
8
25bc
29a
1
3
9
28a
1
26ab
19e
2
1
27.3a 0.8
24.5bc 0.9
26.0ab 0.00
27.5a 0.9
10
11
25bc
1
1
26.5b 0.9
26.7ab 0.8
23bcd
26ab
1
27b
29a
1
1
12
28a
1
2
Rifampicin
26ab
1
24.0a 0.5
24bc
1
26a
1
a Rifampicin = Standard drug
b Values are mean SD of three samples analyzed individually in triplicate at (p<0.01)
c Different letters in superscript indicate significant and non-significant differences within sample
16

Table 8. Antifungal activitya-c of organotin(IV) complexes.
Zone of inhibition (mm)
Complex No.
A. niger
A. flavus
7f
12.0d 0.00
00.0g
A. alternata
G. lucidum
HL
05.5h 0.9
12.5g 0.9
00.0i
1
00.0f
07.5f 0.9
14.0e 0.00
00.0g
1
17e
00.0f
1
2
3
18b
1
16.5b 0.00
14.0c 0.00
14.0cd 0.8
10.5e 0.9
13.5c 0.9
14.2c 0.4
16.9b 0.00
14.7bc 0.8
14.7bc 0.8
16.0b 0.00
19.3b 0.4
17.7de 0.4
18.5b 0.5
18.5cd 0.9
17.5de 0.5
18.0de 0.00
19.9b 0.4
18.2cd 0.4
19.2bc 0.4
19.7b 0.4
22.0a 0.00
17.6b 0.4
14.0e 0.00
17.0bc 0.5
15.5d 0.5
15.7d 0.4
16.0d 0.00
17.9b 0.4
16.5cd 0.5
17.2bc 0.4
17.7b 0.4
4
13.5fg 0.5
15.0cd 0.00
14.0ef 0.00
14.5def 0.5
15.2cde 0.4
19b
15.5cd 0.5
16.0c 0.00
5
6
7
8
9
1
10
11
12
18b
20a
1
1
Fluconazol
19a
1
17a
1
a Fluconazol = Standard drug
b Values are mean SD of three samples analyzed individually in triplicate at (p<0.01)
c Different letters in superscript indicate significant and non-significant differences within sample
17

Figure 1. HOMO-LUMO of 1.
18