New dimeric, trimeric and supramolecular organotin(IV) dithiocarboxylates: Synthesis, structural characterization and biocidal activities

Article abstract of DOI:10.1016/j.poly.2009.07.025

Some new tri-, chlorodi- and diorganotin(IV) dithiocarboxylates (1-10) of 4-benzylpiperidine-1-carbodithioate ligand (L), with general formulae R₃SnL {R = n-C₄H₉ (1), C₆H₁₁ (2), CH₃ (3) and C₆H₅ (4)}, R₂SnClL {R = n-C₄H₉ (5), C₂H₅ (7), CH₃ (9)} and R₂SnL₂ {R = n-C₄H₉ (6), C₂H₅ (8), CH₃ (10)}, have been synthesized by the reaction of organotin(IV) chlorides with the ligand-salt in the appropriate molar ratio. Elemental analysis, Raman, IR, multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) and X-ray crystallographic studies have been undertaken to elucidate the structures of the complexes, both in solution and in solid state. Single-crystal X-ray diffraction study indicate trimeric, dimeric, supramolecular cyclic and supramolecular zig-zag chain structures for complexes 2, 4, 6 and 9, respectively. Square-pyramidal geometry is attributed to complex 9 on the basis of the τ value (0.4). A subsequent antimicrobial study indicates that the compounds are biologically active.

Full text of DOI:10.1016/j.poly.2009.07.025

Polyhedron 28 (2009) 3439–3448
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
New dimeric, trimeric and supramolecular organotin(IV) dithiocarboxylates:
Synthesis, structural characterization and biocidal activities
b
c
Zia-ur-Rehman a,b, Niaz Muhammad a, Shaukat Shuja a, Saqib Ali a, , Ian S. Butler , Auke Meetsma ,
*
Momin Khan d
a Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
b Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Quebec, Canada H3A2K6
c Crystal Structure Center, Chemical Physics, Zernike, Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen, The Netherlands
d Centre of Biotechnology, University of Peshawar, Peshawar, Pakistan
a r t i c l e i n f o
a b s t r a c t
Article history:
Some new tri-, chlorodi- and diorganotin(IV) dithiocarboxylates (1–10) of 4-benzylpiperidine-1-carbod-
ithioate ligand (L), with general formulae R3SnL {R = n-C4H9 (1), C6H11 (2), CH3 (3) and C6H5 (4)}, R2SnClL
{R = n-C4H9 (5), C2H5 (7), CH3 (9)} and R2SnL2 {R = n-C4H9 (6), C2H5 (8), CH3 (10)}, have been synthesized
by the reaction of organotin(IV) chlorides with the ligand-salt in the appropriate molar ratio. Elemental
analysis, Raman, IR, multinuclear NMR (1H, 13C and 119Sn) and X-ray crystallographic studies have been
undertaken to elucidate the structures of the complexes, both in solution and in solid state. Single-crystal
X-ray diffraction study indicate trimeric, dimeric, supramolecular cyclic and supramolecular zig–zag
chain structures for complexes 2, 4, 6 and 9, respectively. Square-pyramidal geometry is attributed to
Received 22 June 2009
Accepted 12 July 2009
Available online 18 July 2009
Keywords:
Organotin(IV) 4-benzylpiperidine-1-
carbodithioates
Trimeric
Dimeric
Supramolecular
Antifungal
complex 9 on the basis of the
s
value (0.4). A subsequent antimicrobial study indicates that the com-
pounds are biologically active.
Ó 2009 Elsevier Ltd. All rights reserved.
Antibacterial
1. Introduction
ziram (zinc-dimethyldithiocarboxylate) and zineb (zinc ethylene-
1,2-bis-dithiocarboxylate) are marketed as fungicides. Organo-
tin(IV) dithiocarboxylates, in particular, are continuing to attract
significant attention because of their structural diversity and vari-
ety of biological applications, e.g., fungicidal, bactericidal, insecti-
cidal and antitumor activity [6–9]. These complexes exert their
toxic effect owing to the non-covalent interactions with the cell
constituents [10]. Encouraged by these findings and our interest
in the field of organotin complexes [11], we decided to synthesize
tin-based dithiocarboxylates with a new ligand, 4-benzylpiperi-
dine-1-carbodithioate, and then screen them for fungicidal and
bactericidal activity, thereby widening their scope in biological
applications (Scheme 2a).
Dithiocarboxylate anions are among the most well-known me-
tal-coordinating agents. These anions are highly effective ligands
for metals owing to the stability of the resulting metal dithiocarb-
oxylates, due to a significant contribution of the resonance form
shown in the Scheme 1 (structure IV) to the overall electronic
structure. Underscoring the affinity of dithiocarboxylate ligands
for metals, these ligands also play a significant role in medicine.
For example, the diethyldithiocarbamate anion, Et2CNS2À, has
had extensive clinical use as antidote for copper poisoning, i.e.,
Wilson’s disease [1] and ameliorating nephrotoxicity associated
with platinum-based chemotherapy [2]. In addition to the medici-
nal uses, metal dithiocarboxylates are used in the vulcanization of
rubber [3], as pesticides [4] and as synthetic precursors for the
deposition of metal sulfide nanoparticles [5]. The synthesis of me-
tal complexes with this type of active ligand is a research area of
increased interest in inorganic, pharmaceutical and medicinal
chemistry as a possible approach to the development of new drugs.
A judicious choice of ligands can modulate the properties of com-
plexes. Consequently, metal-based dithiocarboxylates such as
2. Experimental
2.1. Materials and methods
The reagents, triorganotin(IV) chlorides, diorganotin(IV) dichlo-
rides and 4-benzylpiperidine were obtained from Aldrich Chemical
CO., while CS2 was purchased from Riedal-de Haën. Methanol was
dried before use by the literature procedure [12]. Microanalyses
were performed using a Leco CHNS 932 apparatus. IR spectra were
recorded with KBr pellets in the range from 4000 to 400 cmÀ1
* Corresponding author. Tel.: +92 (051) 90642130; fax: +92 (051) 90642241.
E-mail address: drsa54@yahoo.com (S. Ali).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.07.025

3440
Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
36.5, 32.4, 29.7, (piperidine-C), 42.9, 42.8 (CH2), 140.1, 139.4,
129.1, 129.0, 128.4, 128.3, 126.3, 126.0 (Ar–C).
S
S
S
S
S
S
N
N
N
N
S
S
2.2.2. General procedure for synthesis of complexes
(I)
(II)
(IV)
(III)
Triorganotin(IV) chloride and diorganotin(IV) dichloride in
methanol (30 mL) was added dropwise to the ligand-salt in meth-
anol (50 mL) in the appropriate molar ratio and the mixture was
refluxed for 6 h with constant stirring. The salt was allowed to set-
tle and was removed by filtration. The filtrate was rotary evapo-
rated and the product thus obtained was recrystallized from
chloroform–ethanol (4:1) mixture (Scheme 2a).
Scheme 1. Resonant forms of the –NCSSÀ moiety.
using a Bio-Rad Excaliber FT-IR, model FTS 300 MX spectrometer
(USA). Raman spectra ( 1 cmÀ1) were measured with an InVia Ren-
ishaw spectrometer, using argon-ion (514.5 nm) and near-infrared
diode (785 nm) lasers. WIRE 2.0 software was used for the data
acquisition and spectra manipulations. The 1H and 13C NMR spec-
tra were obtained by a Hg-300 MHz spectrometer and the 119Sn
NMR spectra were recorded on a Varian Unity 500-MHz instru-
ment using Me4Sn as external reference.
2.2.3. Tributyltin(IV) 4-benzylpiperidine-1-carbodithioate (1)
(Yield: 0.46 g, 74%). Sticky material. Anal. Calc. for C25H43NS2Sn
(540.5): C, 55.56; H, 8.02; N, 2.59; S, 11.87. Found: C, 55.49; H,
7.93; N, 2.56; S, 11.81%. Raman (cmÀ1): 587
m
(C–S), 1030
m(C@S),
1440
1467
m(C–N), 504 m(Sn–C), 380 m m(C–S),
(Sn–S). IR (cmÀ1): 965
m
(C–N). 1H NMR (ppm): 1.38–1.28, 3.08–3.04, 1.85–1.78 (m,
3
9H, piperidine-H) 5.19 (d, JH–H = 12.9 Hz, 2H, CH2), 7.33–7.12 (m,
2.2. Syntheses
5H, Ar–H), 1.65–1.20 (m, 18H, H
, SnBu), 0.93 (t, 3JH–H = 7.3 Hz,
, b, c
a
9H, Hd, SnBu). 13C NMR (ppm), [nJ(119Sn, 13C), Hz]: 197.2 (CS), 36.5,
2.2.1. Synthesis of 4-benzylpiperidinium 4-benzylpiperidine-1-
carbodithioate (L-salt)
42.6, 52.4 (piperidine-C), 31.9 (CH2), 139.8, 129.1, 128.5, 126.3
(Ar–C), 17.5 {(C-a, SnBu), [341]}, 29.1 {(C-b, SnBu), [18]} 27.8 {(C-
Carbon disulfide (in excess) in methanol (50 mL) was added
dropwise to 4-benzylpiperidine (5 g, 28.57 mmol) in methanol
(50 mL) and the mixture was stirred for 4 h at 273 K. The solvent
was evaporated under reduce pressure to yield a white product,
which was recrystallized from methanol. (Yield: 4.68 g, 77%).
M.p. 132–134 °C. Anal. Calc. for C25H34N2S2 (426.7): C, 70.37; H,
8.03; N, 6.57; S, 15.03. Found: C, 70.22; H, 7.97; N, 6.61; S,
c
, SnBu), [68]}, 13.7 (C-d, SnBu). 119Sn NMR: d À129.6.
2.2.4. Tricyclohexyltin(IV) 4-benzylpiperidine-1-carbodithioate (2)
(Yield: 0.51 g, 70%). M.p. 122–124 °C. Anal.Calc. for C31H49NS2Sn
(618.6): C, 60.19; H, 7.98; N, 2.26; S, 10.37. Found: C, 60.07; H,
7.90; N, 2.23; S, 10.30%. Raman (cmÀ1): 547
m
(C–S), 1077
m(C@S),
14.91%. Raman (cmÀ1): 644
m
m
(C–S), 1075
m
(C@S), 1455
m
(C–N). IR
1472
1460
m(C–N), 645 m(Sn–C), 370 m m(C–S),
(Sn–S). IR (cmÀ1): 963
(cmÀ1): 1017
m
(C–S), 1453
(C–N). 1H NMR (ppm): 3.04–2.96,
m
(C–N). 1H NMR (ppm): 1.34–1.29, 1.82–1.75, 3.07–2.99 (m,
3
2.60–2.58, 2.82–2.67, 2.60–2.58, 1.84–1.64, 1.35–1.27 (m, 18H,
piperidine-H), 5.77, 3.79 (d, 4H, CH2), 7.34–7.14 (m, 10H, Ar–H),
8.3 (s, 2H, NH2). 13C NMR (ppm): 208.8 (C-1), 51.2, 44.7, 38.2,
9H, piperidine-H) 5.19 (d, JH–H = 13.2 Hz, 2H, CH2), 7.30–7.11 (m,
5H, Ar–H), 1.96–1.24 (m, 33H, H
d, SnC6H11). 13C NMR
a, b, c,
(ppm), [nJ(119Sn, 13C), Hz]: 198.7 (CS), 37.7, 42.8, 52.8 (piperidine-
S
N
a) Dry MeOH
a
NH
+ CS2
b) 4 h stirring
c) 273 K
SH
NH
..
Dry MeOH
6 h reflux
R3SnCl
R
S
S
S
R
Sn
R
N
N
-Salt
S
H2N
R = n-C4H9, C6H11, CH3, C6H5
Dry MeOH
6 h reflux
1/2R2SnCl2
Dry MeOH
6 h reflux
R2SnCl2
-Salt
-Salt
R
R
S
S
S
S
Sn
R
N
N
Cl
Sn
N
S
S
R
R = C4H9, C2H5, CH3
R = n-C4H9, C2H5, CH3
Salt =
NH2Cl
γ
b
δ
γ
H2
C
β
β
β
γ
CH3
α
α
α
β
CH3
α
α
C
δ
H2C
δ
H2C
CH3
H2
,
,
,
,
Scheme 2. (a) Synthesis of ligand-salt and complexes and (b) numbering scheme of organic groups attached to Sn atom.

Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
3441
C), 31.7 (CH2), 140.1, 129.3, 128.5, 126.3 (Ar–C), 35.0 {(C-
a
,
126.6, 128.7, 129.2, 139.1 (Ar–C), 21.3 {(C-
a
, SnEt), [534]}, 10.4 (C-
SnC6H11), [334]}, 32.2 {(C-b, SnC6H11), [16]} 29.5 {(C-
c, SnC6H11),
b, SnEt). 119Sn NMR: d À180.2.
[67]}, 27.2 (C-d, SnC6H11). 119Sn NMR: d 82.3.
2.2.10. Diethyltin(IV) bis[4-benzylpiperidine-1-carbodithioate] (8)
(Yield: 0.29 g, 74%). Sticky material. Anal. Calc. for C30H42N2S4Sn
(677.6): C, 53.17; H, 6.25; N, 4.13; S, 18.93. Found: C, 53.03; H,
2.2.5. Trimethyltin(IV) 4-benzylpiperidine-1-carbodithioate (3)
(Yield: 0.34 g, 71%). M.p. 133–134 °C. Anal.Calc. for C16H25NS2Sn
(414.2): C, 46.39; H, 6.08; N, 3.38; S, 15.48. Found: C, 46.33; H,
6.11; N, 4.10; S, 18.85%. Raman (cmÀ1): 619
m
(C–S), 1028
m
(C@S),
6.03; N, 3.35; S, 15.39%. Raman (cmÀ1): 618
m
(C–S), 1030
m
(C@S),
1455
1459
m(C–N), 493 m(Sn–C), 372 m m(C–S),
(Sn–S). IR (cmÀ1): 961
(C–N). 1H NMR (ppm): 1.32–1.19, 1.82–1.75, 3.11–3.02 (m,
1474
1457
m(C–N), 521 m(Sn–C), 361 m m(C–S),
m
(Sn–S). IR (cmÀ1): 970
m
(C–N). 1H NMR (ppm), [2J(119Sn, 1H), Hz]: 1.39–1.27, 1.82–
3
9H, piperidine-H) 4.74 (d, JH–H = 13.2 Hz, 2H, CH2), 7.28–7.08 (m,
3
3
3
1.75, 3.07–3.03 (m, 9H, piperidine-H) 5.07 (d, JH–H = 12.6 Hz, 2H,
5H, Ar–H), 1.81 {(q, JH–H = 7.5 Hz, 4H, H , SnEt), 1.43 {(t, JH–H
a
CH2), 7.34–7.14 (m, 5H, Ar–H), 1.56 {(s, 9H, H , SnCH3), [57]}.13
C
= 7.5 Hz, 6H, Hb, SnEt) .13C NMR (ppm), [nJ(119Sn, 13C), Hz]: 191.6
a
NMR (ppm), [nJ(119Sn, 13C), Hz]: 201.1 (CS), 36.5, 42.5, 51.8 (piper-
(CS), 36.6, 42.6, 52.6 (piperidine-C), 31.9 (CH2), 126.6, 128.7,
idine-C), 31.8 (CH2), 126.2, 128.4, 129.1, 139.7 (Ar–C), 15.0 {(C-a,
129.2, 139.3 (Ar–C), 29.3 {(C-a, SnEt), [578]}, 10.5 (C-b, SnEt).
SnCH3), [391]}. 119Sn NMR: d À49.8.
119Sn NMR: d À184.6.
2.2.6. Triphenyltin(IV) 4-benzylpiperidine-1-carbodithioate (4)
2.2.11. Chlorodimethyltin(IV) 4-benzylpiperidine-1-carbodithioate (9)
(Yield: 0.39 g, 77%). M.p. 161–163 °C. Anal. Calc. for
C15H22NS2SnCl (434.6): C, 41.45; H, 5.10; N, 3.22; S, 14.75. Found:
C, 41.35; H, 5.04; N, 3.19; S, 14.69%. Raman (cmÀ1): 621
(C–S),
1024 (C@S), 1500 (C–N), 514 (Sn–C), 368 (Sn–S), 249 (Sn–
(C–S), 1459
(Yield: 0.55 g, 79%). M.p. 138–139 °C. Anal.Calc. for C31H31NS2Sn
(600.4): C, 62.01; H, 5.20; N, 2.33; S, 10.68. Found: C, 61.92; H, 5.17;
N, 2.31; S, 10.62%. Raman (cmÀ1): 617
m
(C–S), 1019
m(C@S), 1488
m
m
m
(C–N), 264 m(Sn–C), 370 m m(C–S), 1470
(Sn–S). IR (cmÀ1): 988
m
m
m
m
m
m
(C–N). 1H NMR (ppm): 1.37–1.33, 1.91–1.79, 3.29–3.21 (m, 9H,
Cl). IR (cmÀ1): 961
m
(C–N). 1H NMR (ppm), [2J(119Sn,
3
1H), Hz]: 1.39–1.36, 1.82–1.78, 3.10–3.02 (m, 9H, piperidine-H)
piperidine-H) 4.89 (d, JH–H = 12.3 Hz, 2H, CH2), 7.32–7.17 (m, 5H,
Ar–H), 7.71–7.41 (m, 15H, Hb, , d, SnC6H5). 13C NMR (ppm): 193.3
3
c
4.66 (d, JH–H = 13.2 Hz, 2H, CH2), 7.30–7.10 (m, 5H, Ar–H), 1.36
{(s, 6H, SnMe), [82]}. 13C NMR (ppm), [nJ(119Sn, 13C), Hz]: 194.9
(CS), 36.6, 41.8, 53.2 (piperidine-C), 31.6 (CH2), 125.9, 128.5,
129.0, 140.1 (Ar–C), 142.9 (C-a, SnC6H5), 136.4 (C-b, SnC6H5),
(CS), 36.9, 42.4, 52.7 (piperidine-C), 31.8 (CH2), 126.6, 128.7,
, SnC6H5), 129.1 (C-d, SnC6H5). 119Sn NMR: d À182.2.
129.2, 139.5 (Ar–C), 10.2 (C-
a
, SnMe), [571]}. 119Sn NMR: d À201.2.
128.9 (C-
c
2.2.7. Chlorodibutyltin(IV) 4-benzylpiperidine-1-carbodithioate (5)
2.2.12. Dimethyltin(IV) bis[4-benzylpiperidine-1-carbodithioate] (10)
(Yield: 0.30 g, 80%). M.p. 180–184 °C. Anal. Calc. for
C28H38N2S4Sn (649.6): C, 51.77; H, 5.90; N, 4.31; S, 19.74. C,
51.67; H, 5.82; N, 4.28; S, 19.66%. Raman (cmÀ1): 622
(C–S),
(Sn–S). IR (cmÀ1):
(C–N). 1H NMR (ppm), [2J(119Sn, 1H), Hz]:
1.39–1.28, 1.80–1.78, 3.04–2.95 (m, 9H, piperidine-H) 4.66 (d,
3JH–H = 13.2 Hz, 2H, CH2), 7.30–7.10 (m, 5H, Ar–H), 1.36 {(s, 6H,
SnMe), [90]}. 13C NMR (ppm): 195.1 (CS), 36.9, 42.1, 52.7 (piperi-
(Yield: 0.47 g, 77%). Sticky material. Anal.
Calc. for
C21H34NS2SnCl (518.8): C, 48.62; H, 6.61; N, 2.70; S, 12.36. Found:
C, 48.53; H, 6.54; N, 2.67; S, 12.30%. Raman (cmÀ1): 619
m
(C–S),
m
1031
m
(C@S), 1445
m
m
(C–N), 581
(C–S), 1475
m(Sn–C), 345 m(Sn–S), 255 m(Sn–
1030
971
m
m
(C@S), 1474 m(C–N), 511 m(Sn–C), 364 m
(C–S), 1451 m
Cl). IR (cmÀ1): 968
m
(C–N). 1H NMR (ppm): 1.37–
3
1.27, 1.86–1.78, 3.11–3.03 (m, 9H, piperidine-H) 4.72 (d, JH–H
= 12.9 Hz, 2H, CH2), 7.31–7.09 (m, 5H, Ar–H), 1.99–1.31 (m, 12H,
3
H
a
, SnBu), 0.93 (t, JH–H = 6.9 Hz, 6H, Hd, SnBu). 13C NMR
,
b,
c
(ppm), [nJ(119Sn, 13C), Hz]: 195.6 (CS), 36.4, 42.5, 52.7 (piperidine-
C), 31.9 (CH2), 139.2, 129.2, 127.5,126.6 (Ar–C), 26.5 {(C- , SnBu),
, SnBu), [67]}, 13.9 (C-d,
dine-C), 31.6 (CH2), 126.6, 128.7, 129.2, 139.3 (Ar–C), 10.5 (C-a,
a
SnMe). 119Sn NMR: d À337.0.
[590]}, 36.4 {(C-b, SnBu), [18]}, 28.7 {(C-
c
SnBu). 119Sn NMR: d À175.0.
2.3. X-ray crystallographic studies
2.2.8. Dibutyltin(IV) bis[4-benzylpiperidine-1-carbodithioate] (6)
Acrystalfragment,cuttosizetofitinthehomogeneouspartofthe
X-raybeam, wasmountedon topofaglassfiberandalignedonaBru-
ker SMART APEX CCD diffractometer (platform with full three-circle
goniometer). The crystal was cooled to 100(1) K using the Bruker
KRYOFLEX low-temperature device. Intensity measurements were
(Yield: 0.33 g, 76%). M.p. 141–142 °C. Anal.
Calc. for
C34H50N2S4Sn (733.7): C, 55.65; H, 6.87; N, 3.82; S, 17.48. Found:
C, 55.56; H, 6.80; N, 3.78; S, 17.41%. Raman (cmÀ1): 587
m(C–S),
1028
m
(C@S), 1473
m(C–N), 503 m(Sn–C), 334 m
(Sn–S). IR (cmÀ1):
969
m
(C–S), 1465
m
(C–N). 1H NMR (ppm): 1.40–1.30, 1.86–1.78,
3
performed using graphite monochromatized Mo Ka radiation from
3.42–3.37 (m, 9H, piperidine-H) 4.89 (d, JH–H = 12.3 Hz, 2H, CH2),
a sealed ceramic diffraction tube (SIEMENS). X-ray diffraction data
were collected on a Bruker SMART APEX CCD diffractometer which
was equipped with a 4 K CCD detector set 60.0 mm from the crystal.
Data integration and global cell refinement was performed with the
program SAINT. The program suite SAINTPLUS was used for space group
determination(XPREP).ThestructurewassolvedbyPattersonmethod;
extension of the model was accomplished by direct methods and ap-
pliedtodifferentstructurefactorsusingtheprogramDIRDIF.Allrefine-
ment calculations and graphics were performed with the program
PLUTO and PLATON package.
7.28–7.09 (m, 5H, Ar–H), 1.85–1.33 (m, 12H, H
, SnBu), 0.93
a, b, c
3
(t, JH–H = 7.2 Hz, 6H, Hd, SnBu). 13C NMR (ppm), [nJ(119Sn, 13C),
Hz]: 190.6 (CS), 36.7, 42.5, 52.5 (piperidine-C), 31.9 (CH2), 139.4,
128.7, 127.5, 126.5 (Ar–C), 26.5 {(C-
a
, SnBu), [601]}, 36.7 {(C-b,
SnBu), [19]}, 29.3 {(C-
c
, SnBu), [68]}, 13.9 (C-d, SnBu). 119Sn
NMR: d À201.1.
2.2.9. Chlorodiethyltin(IV) 4-benzylpiperidine-1-carbodithioate (7)
(Yield: 0.43 g, 79%). M.p. 125–126 °C. Anal.
Calc. for
C17H26NS2SnCl (462.7): C, 44.13; H, 5.66; N, 3.03; S, 13.86. Found:
C, 44.05; H, 5.59; N, 3.00; S, 13.79%. Raman (cmÀ1): 620
m
(C–S),
1031
m
(C@S), 1446
m
(C–N), 476
m
(Sn–C), 370
m
(Sn–S), 271
m
(Sn–Cl).
3. Results and discussion
IR (cmÀ1): 963
m
(C–S), 1463 m
(C–N). 1H NMR (ppm): 1.32–1.19,
1.82–1.75, 3.11–3.02 (m, 9H, piperidine-H) 4.72 (d, 3JH–H = 13.2 Hz,
3.1. Syntheses of ligand-salt and complexes 1–10
3
2H, CH2), 7.30–7.08 (m, 5H, Ar–H), 1.81 {(q, JH–H = 7.5 Hz, 4H, H ,
a
SnEt), 1.46 {(t, 3JH–H = 7.5 Hz, 6H, Hb, SnEt) .13C NMR (ppm), [nJ(119Sn,
The new organotin(IV) 4-benzylpiperidine-1-carbodithioate
complexes were prepared by the reaction of the ligand-salt (L-salt)
13C), Hz]: 195.5 (CS), 36.4, 42.5, 51.7 (piperidine-C), 31.9 (CH2),

3442
Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
with the selected triorganotin(IV) chlorides and diorganotin(IV)
dichlorides in the appropriate mole ratio in dry methanol (Scheme
2a). The numbering system for the organic groups attached to Sn is
given in scheme 2b. The compounds 1–10 are quite stable in moist-
air and are soluble in common organic solvents.
derivatives could not be calculated due to their complex peak pat-
tern. In case of compound 4, the difference in chemical shift reso-
nances of ortho to meta and para protons (0.3 ppm) is an indication
of anisobidentate bonding of 1,1-dithiolate moiety in solution [17].
The 13C NMR chemical shifts due to organic groups, attached to
Sn atom, were observed at positions comparable to the other sim-
ilar compounds [18]. The disappearance of duplicate peak pattern
and a small shift in the position of CS carbon confirmed the coor-
dination of ligand to the Sn center via CSS moiety. In organotin
compounds, the 1J(119Sn, 13C) coupling constant can be used to as-
sess the coordination number of the Sn atom. The coupling con-
stants were calculated and found to be in the order of 341 Hz for
tributhyltin 1, 334 Hz for tricyclohexyltin 2 and 391 Hz for tri-
methyltin 3 compounds which are the typical values for tetrahe-
dral compounds [19] as given in Table 1. A characteristic feature
for triphenyltin derivative is the observance of 13C chemical shift
of the ipso-carbon at about 142.9 ppm which is attributed to a
five-coordinated Sn atom [20]. The calculated value of the
1J(119Sn, 13C) coupling constant for 5, 6, 7, 8 and 9 are 590, 601,
534, 578 and 571 Hz, respectively which described the penta-coor-
dinated environment about the Sn atom in these compounds.
The 119Sn chemical shift values obtained for triorganotin(IV)
complexes lie in the range expected for tetrahedral geometry, ex-
cept for the Ph3Sn(IV) complex which gave a 119Sn peak corre-
sponding to a five-coordinated Sn atom. The 119Sn NMR data for
the chlorodi- and diorganotin(IV) compounds are in conformity
with five coordination around the Sn atom. Among the diorgano-
tin(IV) derivatives, only complex 10 furnished a 119Sn peak associ-
ated with the octahedral geometry in solution [21].
3.2. Vibrational spectra
The assignment of the Raman bands of the complexes has been
made by comparison with the Raman spectra of their related pre-
cursors. In the complexes, the appearance of a new peak in the re-
gion 334–380 cmÀ1 owing to a Sn–S vibration indicated the
formation of complexes. In addition, all the complexes displayed
a sharp Sn–C peak in the range 476–645 cmÀ1, except for the tri-
phenyltin(IV) derivative where a weak vibration appeared at
263 cmÀ1 due to Sn–C stretching. A peak associated with
m(Sn–
Cl) was observed in the chlorodiorganotin(IV) derivatives only,
which indicates the substitution of one chloride in the diorganotin
salt during the reaction.
With respect to the dithiocarboxylate moiety, two main regions
of the IR are of particular interest. First, the 1450–1580 cmÀ1 re-
gion, which is primarily associated with the ‘thioureide’ band
due to the
which is associated with
peak due to
m
(N–CSS) vibration; second, the 940–1060 cmÀ1 region,
m
(C–S) stretching. The stretching vibration
m
(N–CSS), in the complexes studied here were located
in the range 1457–1475 cmÀ1. These values lie between the range
reported for C–N single bond (1250–1360 cmÀ1) and C@N double
bond (1640–1690 cmÀ1), and is an indication of partial double
bond character in C–N bond [13]. The presence of a band in the
above-mentioned range for
resonance structures (Scheme 1). On passing from the ligand-salt
to the complexes, the (N–CSS) mode is shifted to higher energies,
showing an increase of C–N double bond character [14]. Regarding
the chlorodiorganotin(IV) derivatives, the (N–CSS) band is shifted
to higher energy as compared to diorganotin(IV) complexes owing
to the presence of electron-withdrawing effect of chloride in the
complexes, thus promoting a higher positive charge on nitrogen
atom. A single band for C–S in the region of 900–1060 cmÀ1, in
complexes, is in accord with bidentate bonding of 1,1-dithiolate
moiety with Sn [15].
m(N–CSS) is due to the four possible
3.4. X-ray structures
m
3.4.1. Crystal structures of compound 2, 4, 6 and 9
m
An ORTEP view of compound 2 together with atomic numbering
scheme is depicted in Fig. 1. Pertinent crystallographic parameters,
relevant bond lengths and bond angles are given in Tables 2 and 3.
The Sn atom is five-coordinate, being chelated by asymmetrically
coordinating 4-benzylpiperidine-1-carbodithioate ligand and three
cyclohexyl substituents. The Sn–S1 [3.160 Å] bond distance
approximately trans- to the C26 is longer than the other Sn–S2
[2.4756(9) Å] bond distance. According to Addison et al., the geom-
3.3. NMR spectra
etry around the Sn atom can be characterized by the value of
(b À )/60 [22], where b is the largest of the basal angles around
the Sn atom. The angle = b = 180° correspond to a square-pyrami-
dal geometry, and the value of = 120° corresponds to perfectly
trigonal-bipyramidal geometry. Thus, the value is equal to zero
s =
The 1H NMR spectra were recorded for the compounds 1–10 in
DMSO-d6. The characteristic chemical shifts were identified by
their intensity and multiplicity patterns. The total number of pro-
tons, calculated from the integration curves, is in agreement with
the expected molecular composition of the compounds. For the li-
gand, the piperidine protons demonstrate three triplets (1.78–1.85,
1.27–1.39 and 3.04–3.08 ppm) in the aliphatic region as expected
for the structure. The protons of the benzyl part resonate in two re-
gions; a doublet (ꢀ5.07 ppm) due to CH2 protons and a multiplet
(7.12–7.33 ppm) because of phenyl moiety. The proton chemical
shifts assignment of the organic groups attached to Sn exhibited
a singlet at ꢀ1.53 ppm for compounds 3, 9 and 10 and appeared
as multiplets in the aliphatic region in case of compounds 1, 2, 5
and 6. The protons of the ethyltin(IV) derivatives appeared as a
quartet and a triplet as expected, while the aromatic protons of
the triphenyltin(IV) complex resonate as multiplets in the range
7.42–7.71 ppm. The 2J [119Sn, 1H] coupling constant value for com-
plex 3 was 57 Hz, in the range normally expected for four-coordi-
nate Sn and consistent with CSnC angle of 110.9° while the angle
calculated (Table 1) from 2J [119Sn, 1H] coupling constant certify
the 5- and six-coordinate environment around Sn for compounds
9 and 10, respectively [16]. However, the coupling constants, 2J
a
a
a
s
for a perfect square-pyramidal and unity for a perfect trigonal-
bipyramidal. For compound 2, b is S1–Sn–C26 = 157.39°. The sec-
ond largest of the basal angles around the Sn atom,
2 is S2–Sn–C20 = 116.84(8)°. The calculated value for the 2 is
a for compound
s
0.67, and is an indicative of highly distorted trigonal-bipyramidal
Table 1
(C–Sn–C) angles (°) based on NMR parameters of selected compounds.
Compound Number
1J(119Sn, 13C) (Hz)
2J(119Sn, 1H) (Hz)
Angle (°)
1J
2J
1
2
3
5
6
7
8
9
341
334
391
590
601
534
578
571
106.6
106.0
111.0
128.5
129.5
123.6
127.4
126.8
57
110.9
82
90
127.5
135.5
10
[
119Sn, 1H] for n-butyl-, cyclohexyl-, ethyl- and triphenyltin(IV)

Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
3443
Fig. 1. ORTEP drawing of compound 2 with atomic numbering scheme.
Table 2
Crystal data and structure refinement parameters for compounds 2, 4, 6 and 9.
2
4
6
9
Empirical formula
Formula mass
Crystal system
Space group
a (Å)
C31H46NS2Sn
615.55
C31H31NS2Sn
600.38
C34H50N2S4Sn
733.75
C15H22NS2SnCl
434.64
monoclinic
P21
13.2495(12)
9.7868(9)
13.6949(12)
triclinic
triclinic
triclinic
ꢀ
ꢀ
ꢀ
P1
P1
P1
10.5063(10)
10.6281(10)
15.0438(15)
109.3918(12)
103.1745(12)
92.5424(13)
1529.6(3)
9.2531(8)
10.7273(9)
14.4044(12)
95.313(10)
101.880(10)
94.328(10)
1386.6(2)
2
9.7767(13)
10.9801(15)
17.105(2)
89.8273(19)
79.0265(18)
80.4534(19)
1776.9(4)
2
b (Å)
c (Å)
a
(°)
b (°)
90.7045(11)
c
(°)
V (Å3)
1775.7(3)
4
Z
2
Crystal size (mm)
Total reflections
Independent reflections
All
0.44 Â 0.37 Â 0.17
0.50 Â 0.45 Â 0.40
0.25 Â 0.35 Â 0.47
0.55 Â 0.50 Â 0.42
13801
10780
20874
14351
7234
6477
0.0401
0.1180
4936
10225
7585
0.0528
0.1302
8608
8251
0.0302
0.0780
For Fo P 4.0
r
(Fo)
P
P
R(F) = (||Fo| À |Fc||)/ |Fo| for Fo > 4.0
r
(Fo)
0.0299
P
P
wR(F2) = [ [w(Fo À Fc2) ]/ [w(Fo2) ]]
2
2
1/2
2
R indices (all data)
R1 = 0.0278, wR2 = 0.0750
R1 = 0.0228, wR2 = 0.0530
1.197
Final R indices [I > 2
r(I)]
Goodness-of-fit (GOF)
1.037
1.034
1.026
h range for data collections (°)
Data/restraints/parameters
2.68–28.28
7234/0/316
2.41–25.93
4936/0/316
2.51–25.68
10225/0/581
2.56–28.28
8608/0/365
geometry. The C26 atom occupies one of the apical positions of the
trigonal-bipyramid with the C26–Sn–S2 angle of 95.35(8)°. The
quasi-axial S1 atom cannot occupy exactly the position trans to
C26 and C26–Sn–S1 angle is 157.39°. Thus, ligand chelates the Sn
atom via its two sulfur atoms in anisobidentate fashion, forming
a four-membered ring with S1–Sn–S2 bond angle of 62.80°. The
S–C bond lengths [S1–C13 = 1.691(3) Å and S2–C13 = 1.768(3) Å]
also demonstrate the asymmetric nature of the ligand. The packing
diagram confirmed trimeric structure for compound 2, formed as
the result of intermolecular HÁ Á ÁH interactions (Fig. 2).
Table 3
Selected bond lengths (Å) and bond angles (°) for compound 2.
Sn–S2
2.4756(9)
2.181(3)
1.691(3)
3.160
Sn–C14
Sn–C26
S2–C13
2.170(3)
2.184(3)
1.768(3)
Sn–C20
S1–C13
Sn–S1
S2–Sn–C14
S2–Sn–C20
S2–Sn–C26
C14–Sn–C20
C14–Sn–C26
C20–Sn–C26
Sn–C14–C15
Sn–C20–C21
Sn–C26–C27
112.09(8)
116.84(8)
95.35(8)
115.11(12)
108.77(11)
106.30(12)
114.36(19)
109.4(2)
S1–Sn–C14
S1–Sn–C20
S1–Sn–C26
S1–Sn–S2
Sn–S2–C13
Sn–S1–C13
Sn–C14–C19
Sn–C20–C25
Sn–C26–C31
86.33
80.78
157.39
62.80
98.97(1)
78.00
109.9(2)
113.4(2)
112.4(2)
The molecular structure of compound 4 is shown in Fig. 3, while
crystal data and selected bond lengths and bond angles are given in
Tables 2 and 4, respectively. The geometry around Sn is almost a
midway between square-pyramidal and trigonal-bipyramidal as
112.2(2)
evident from the
s value (0.66). The value indicates a highly

3444
Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
Fig. 2. Loosely associated trimer in compound 2, connected through weak intermolecular cyclohexyl HÁ Á ÁH interactions.
Fig. 3. ORTEP drawing of compound 4 with atomic numbering scheme.
distorted trigonal-bipyramidal arrangement around the Sn1 atom
with C26 from a phenyl group and the S2 from the dithiocarboxyl-
ate ligand at the axial positions while C14 and C20 from two phe-
nyl groups and S1 in the plane positions. The sum of the equatorial
angles is 350° instead of the ideal value of 360°. Being a part of che-
late, the angle S2–Sn1–S1 is not 90° but only 65.70°, so the S2 can-
not occupy exactly the corresponding trans apical position of C26
and the angle between the apical groups is 158.88°. Finally, the
C–S bond lengths are characteristic of the 1,1-dithiolate moiety
and are intermediate between the values expected for single and
double bonds [23]. The packing diagram indicated
tions that gave rise to a dimeric structure (Fig. 4).
pÁ Á ÁH interac-
Crystal data and selected interatomic parameters for compound
6 are collected in Tables 2 and 5, respectively. An ORTEP view of
the molecule including numbering scheme is shown in Fig. 5. The
Sn atom in 6 is coordinated by two butyl groups and two 4-ben-
zylpiperidine-1-carbodithioate ligands, with the latter adopting
different asymmetric coordination modes. The first dithiocarboxyl-
ate ligand is chelating but forms asymmetric Sn–S bond distances
of 2.5315(14) Å and 2.9574(15) Å, respectively, while for the sec-
ond ligand, Sn–S bond lengths are 2.5470(14) Å and 2.8970
(16) Å. The weaker Sn–S distances are well within the sum of the
van der Waals radii for the Sn and S atoms (4.0 Å). The overall
geometry at Sn is, however, highly distorted from the trans octahe-
dral: the C27–Sn–C31 angle is only 137.3(2)° which is intermediate
between cis and trans, the Sn and the four S atoms of the ligands
are nearly coplanar but distorted from square-planar geometry,
so that the cis S2-Sn–S4 angle is only 83.89(4)° and the cis S1-
Table 4
Selected bond lengths (Å) and bond angles (°) for compound (4).
S1–Sn1
C14–Sn1
C26–Sn1
C1–S1
2.4892(8)
2.144(3)
2.173(3)
1.758(3)
Sn1–S2
C20–Sn1
C1–S2
2.935
2.156(3)
1.696(3)
C14–Sn1–S1
115.38(8)
93.88(9)
83.72
C20–Sn1–S1
C14–Sn1–S2
C26–Sn1–S2
119.21(9)
89.50
158.88
C26–Sn1–S1
C20–Sn1–S2
C14–Sn1–C20
115.43(11)
103.11(11)
80.75
C14–Sn1–C26
C1–S1–Sn1
S2–C1–S1
104.96(11)
94.00(10)
118.35(18)
C20–Sn1–C26
C1–S2–Sn1
S1–Sn–S2
65.70

Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
3445
gands. The bond angles subtended at the Sn atom by the methylene
carbons and S2 and S4 atoms range from 104.45(14)° to
107.05(18)° demonstrating that the Sn–C bonds are bent toward
the longer Sn–S bonds. This situation must be a consequence of
repulsion between the bonding electron pairs around the central
Sn atom. Electronic and steric arguments have also been invoked
to account the distortion of the similar structures from the regular
octahedral geometry. Thus, the coordination geometry about the
Sn atom in compound 6 is best described as being distorted skew
trapezoidal-bipyramidal. Secondary
in compound 6, result in a supramolecular cyclic structure as
p
Á Á ÁH and HÁ Á ÁH interactions,
shown in Fig. 6.
The asymmetric unit of complex 9 contains two different mole-
cules. An ORTEP diagram for one of the two independent mole-
cules, together with an example of the atom numbering scheme
used here is shown in Fig. 7. Crystal data and selected interatomic
parameters are collected in Tables 2 and 6, respectively. The con-
figuration about the tin atom is five-coordinate. The sum of the
Fig. 4. Loosely associated dimer in compound 4, connected through weak inter-
molecular
pÁ Á ÁH interactions.
equatorial angles involving the two a-carbons of the methyl groups
and a S atom [S11, S22]: 358.7°, show little deviation from the ideal
angle of 360°. The coordination geometry, for both molecules, is al-
most intermediate between square-pyramidal and trigonal-bipyra-
Table 5
Selected bond lengths (Å) and bond angles (°) for compound (6).
midal with a slight bias towards the former, based on the
s value
Sn–S1
Sn–S3
Sn–C27
S1–C13
S3–C26
2.9574(15)
2.8970(16)
2.141(7)
1.701(5)
1.695(6)
Sn–S2
Sn–S4
Sn–C31
S2–C13
S4–C26
2.5315(14)
2.5470(14)
2.135(5)
1.743(5)
1.731(5)
(0.40 and 0.44). A concrete explanation is available for the devia-
tion of the coordination geometries towards square-pyramidal. In
complex 9, a secondary SnÁ Á ÁS interaction is responsible for lower-
ing the
s value, which leads to the formation of a supramolecular
S1–Sn–S2
S1–Sn–S4
S1–Sn–C31
S2–Sn–S4
S2–Sn–C31
S3–Sn–C27
S4–Sn–C27
C27–Sn–C31
Sn–S2–C13
Sn–S4–C26
S3–C26–S4
64.95(4)
S1–Sn–S3
S1–Sn–C27
S2–Sn–S3
S2–Sn–C27
S3–Sn–S4
S3–Sn–C31
S4–Sn–C31
Sn–S1–C13
Sn–S3–C26
S1–C13–S2
145.29(4)
84.57(18)
149.76(5)
107.05(18)
65.87(4)
82.95(14)
104.45(14)
81.33(18)
81.43(18)
119.1(3)
zig–zag chain structure (Fig 8). For each molecule, the Cl atom
occupies one of the apical positions of the highly distorted trigo-
nal-bipyramid with the Cl1–Sn1–S11 and Cl2–Sn2–S22 angles of
86.57(3)° and 86.49(3)°, respectively. The quasi-axial S12 and
S21 atoms cannot occupy exactly the position trans to Cl and
Cl1–Sn1–S12 and Cl2–Sn2–S21 angles are 155.58(3)° and
155.38(3)°. Thus, the dithiocarboxylate group in both molecules
is asymmetrically coordinated, and in each molecule Sn–S
[Sn1–S12 = 2.6765(11) Å, Sn2–S21 = 2.6961(11) Å] bond length
approximately trans to the chloride is longer than the other Sn–S
[Sn1–S11 = 2.4908(9) Å and Sn2–S22 = 2.4866(9) Å] bond distance.
The S–C bond lengths [(Sx1–Cx13 = 1.745(5) Å and 1.706(3) Å) and
(Sx2–Cx13 = 1.711(3) Å and 1.763(5) Å)] also illustrate the asym-
metric nature of the dithiocarboxylate group in each molecule.
148.84(4)
84.61(14)
83.89(4)
105.35(15)
82.93(18)
106.03(19)
137.3(2)
94.39(16)
92.06(18)
120.5(3)
Sn–S3 angle is 145.29(4)°. In both anisobidentate ligands, each
shorter Sn–S bond is associated with a longer C–S bond and vice
versa; this is in consonance with the bonding asymmetry of the li-
Fig. 5. ORTEP drawing of compound 6 with atomic numbering scheme.

3446
Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
Fig. 6. Supramolecular cyclic structure of compound 9 mediated by secondary
pÁ Á ÁH and HÁ Á ÁH interactions.
Fig. 7. ORTEP drawing for one of two independent molecules of compound 9 with atomic numbering scheme.
Table 6
Selected bond lengths (Å) and bond angles (°) for compound (9).
x = 1
x = 2
x = 1
x = 2
Snx–Clx
2.5024(10)
2.6765(11)
2.123(4)
2.4976(10)
2.4866(9)
2.131(4)
Snx–Sx1
Snx–Cx14
Sx1–Cx13
2.4908(9)
2.122(3)
1.745(5)
2.6961(11)
2.123(3)
1.706(3)
Snx–Sx2
Snx–Cx15
Sx2–Cx13
1.711(3)
1.763(5)
Clx–Snx–Sx1
86.57(3)
96.86(16)
69.18(4)
114.86(11)
91.51(13)
89.76(11)
116.4(3)
155.38(3)
97.38(13)
69.08(4)
92.02(13)
116.36(11)
84.63(17)
116.1(2)
Clx–Snx–Sx2
155.58(3)
96.32(16)
112.38(10)
95.12(16)
131.48(15)
84.50(17)
86.49(3)
Clx–Snx–Cx14
Sx1–Snx–Sx2
Sx1–Snx–Cx15
Sx2–Snx–Cx15
Snx–Sx1–Cx13
Sx1–Cx13–Sx2
Clx–Snx–Cx15
Sx1–Snx–Cx14
Sx2–Snx–Cx14
Cx14–Snx–Cx15
Snx–Sx2–Cx13
96.38(13)
95.20(13)
113.47(10)
128.86(15)
90.16(11)
By comparing the Sn–S bond lengths, the shorter Sn–S bond dis-
tance decreases in the following order: 6 > 4 > 2 > 9 and the longer
SnÁ Á ÁS bond value decreases in the sequence: 2 > 6 > 4 > 9. The
smallest Sn–S bond distances for compound 9 in the series is pre-
sumably due to two reasons: firstly the less steric hindering
methyl groups and secondly electron-withdrawing effect of the
chloride group that increases electron accepting capability of the
Sn atom. For Sn–Sshorter, the high value for compound 4 might be
due to the back-donation capability of the phenyl groups, thus sta-
bilizing Sn atom d-orbitals and reducing their interactions with
S-orbitals of the ligand. For complex 6 the highest value can be
explained on the basis of electron-donating effect of the butyl
groups which increase the electron density on Sn atom as a conse-
quence repulsion between Sn and S atoms increase. In the case of
Sn–Slonger, the order for complexes 2, 4 and 6 can be explained
on the basis of steric reasons. The high value for complex 2 is
due to high steric hindrance of the cyclohexyl groups as compared
to the phenyl and butyl groups.

Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
3447
Fig. 8. Supramolecular zig–zag chain in the structure of compound 9 mediated by secondary SnÁ Á ÁS and benzyl-CÁ Á ÁH interactions.
Table 7
Antifungal activitya of organotin(IV) derivatives 1–10.
Sample
Tested fungi
A. nigar
A. flavus
H. solani
A. solani
Fusarium sp.
Linear growth % inhibition Linear growth % inhibition Linear growth % inhibition Linear growth % inhibition Linear growth % inhibition
Control
Ld
(1)
(2)
(3)
(4)
(5)
(6)
(7)
85
86
87
90
70
56
70
70
70
60
56
63
63
61
60
70
44
48.0
50.0
78.0
80.0
68.0
72.0
66.0
72.0
80.0
66.0
76.0
43.5
41.2
8.2
63.0
65.0
73.0
78.0
66.0
73.0
80.0
74.0
78.0
69.0
76.0
52
26.7
24.4
15.1
9.3
23.3
15.1
7.0
14.0
9.3
19.8
11.6
39.5
76.0
80.0
80.0
81.0
70.0
61.0
73.0
78.0
68.0
73.0
80.0
51
12.6
8.0
8.0
74.0
84.0
76.0
76.0
68.0
66.0
70.0
68.0
64.0
66.0
73.0
48
17.8
6.7
20
0
0
15.6
15.6
24.4
26.7
22.2
24.4
28.9
26.7
18.9
46.7
5.9
6.9
0
20.0
15.3
22.4
15.3
5.9
22.4
10.6
29.4
19.5
29.9
16.1
10.3
21.8
16.1
8.0
14.2
20
10
10
12.8
14.2
0
(8)
(9)
(10)
Clotrimazole 60
41.4
37.1
a
Concentration: 200
lg/mL of DMSO.
A comparison of the
s
values for the five-coordinate complexes
movement of ribosome along with RNA. This situation would inhi-
bit synthesis of DNA in the cell nucleus [10]. The higher activity of
complex 1 may be due to highest lipophilic character of tributyl-
tin(IV) derivatives [24]. The ligand and tributyltin(IV) complex
are more active than is the standard drug against A. nigar and these
compounds have potential to be used as fungicides in future.
2, 4 and 9 reveals the smallest value for complex 9 because of sec-
ondary SnÁ Á ÁS intermolecular interactions. The presence of such
kinds of interaction in compound 9 only, is due to the presence
of small methyl groups on one end, that allow the molecules to ap-
proach one another closely. Secondly the presence of electronega-
tive chloride group makes the Sn atom electron deficient and thus
facilitates its interaction with S atom of the adjacent molecule.
3.5.2. Antibacterial activity
The compounds 1–10 were tested by agar well diffusion meth-
od against five different types of bacteria, namely, Escherichia coli,
Salmonella typhi, Pseudomonas aeroginosa, Staphylococcus auerus
and Streptococcus, Streptomycin was used as the reference drug
and the results are presented in Table 8. Almost all the compounds
were more toxic than was their parent ligand but slightly less so
than the standard drug. Among the triorganotin(IV) derivatives,
the bactericidal activity of 1 and 4 are fairly good; however, neither
of these complexes (1–4) demonstrated any activity against Staph-
lococcus aureus. The chlorodiorganotin(IV) complexes were found
to be more active than their counterparts without chloride substit-
uents. The most probable reason is the ease of hydrolysis of the for-
mer [25]. The enhanced bactericidal activity of the ligand on
complexation with organotin moiety may be explained by chela-
tion theory [26], according to which chelation reduces the polarity
of the central Sn atom because of the partial sharing of its positive
3.5. Biocidal activities
3.5.1. Antifungal activity
The agar tube dilution protocol method was employed to test
the antifungal activities of the synthesized compounds against
the five different strains of fungi Aspergillusnigar, A. flavus, Helmin-
thosporium solani, Alternia solani, Fusarium sp. and the results are
shown in Table 7. The activity of compounds is highly strain
dependent. Triorganotin(IV) derivatives are more active than are
the chlorodi- and diorganotin(IV) complexes against the A. nigar
and A. flavus. However, for the other three species, the order is re-
versed which is an indication of different mode of interaction of
these compounds with the strains studied. The different mecha-
nism of these compounds may be due to their ability to form sec-
ondary intermolecular interactions (as can be seen in crystal
packing diagram) with bioreceptors in the cells of the microorgan-
isms, which in turn block the synthesis of protein by inhibiting the
charge with donor groups and possible
p-electrons delocalization
within the whole chelating ring. As a result, the lipophilic nature

3448
Zia-ur-Rehman et al. / Polyhedron 28 (2009) 3439–3448
Table 8
Antibacterial activity dataa,b of organotin(IV) derivatives 1–10.
Bacterium
Clinical implication
Zone of inhibition (mm)
Reference drug
L
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
E. coli
S. typhi
P. aeroginosa
Staphylococcus aureus
Streptococcus
infection of wounds, urinary tract and dysentery
typhoid fever, localized infection
infection of wounds, eyes, septicemia
food poisoning, scaled skin syndrome, endocarditis
Strep throat
22
16
17
12
0
25
23
16
0
12
12
0
0
11
11
17
13
0
23
19
0
0
21
14
19
10
15
11
13
17
0
19
13
19
23
14
15
17
17
20
16
11
17
18
21
14
11
17
0
13
0
10
11
34
31
24
38
38
18
0
a
In vitro, agar well diffusion method, conc. 1 mg/mL of DMSO.
Reference drug, Streptomycin.
b
[3] P.J. Nieuwenhuizen, J. Reedijk, M. van Duin, W.J. McGill, Rubber Chem. Technol.
70 (1997) 368.
[4] M. Cicotti, Handbook of Residue Analytical Methods for Agrochemicals, vol. 2,
Wiley, Chichester, 2003.
of the central Sn atom increases, which favors the permeation of
the complexes through the lipid layer of the cell membrane.
[5] D. Fan, M. Afzaal, M.A. Malik, C.Q. Nguyen, P. O’Brien, P.J. Thomas, Coord. Chem.
Rev. 251 (2007) 1878.
4. Conclusions
[6] P.K. Gogoi, D.P. Phukan, D.K. Das, Asian J. Chem. 11 (1999) 1291.
[7] H.P.S. Chauhan, N.M. Shaik, J. Inorg. Biochem. 99 (2005) 538.
[8] G. Eng, X. Song, Q. Duong, D. Strickman, J. Glass, L. May, Appl. Organomet.
Chem. 17 (2003) 218.
[9] H.D. Yin, S.C. Xue, Appl. Organomet. Chem. 20 (2006) 283.
[10] R. Mash, Ann. Appl. Biol. 41 (1954) 652.
[11] Z. Rehman, A. Shah, N. Muhammad, S. Ali, R. Qureshi, I.S. Butler, J. Organomet.
Chem. 694 (2009) 1998.
[12] W.F.L. Armarego, C. Chai, Purification of Laboratory Chemicals, 5th ed.,
Butterworth, Oxford, 2003.
The presence of intermolecular interactions in packing dia-
grams can be exploited to conclude that these compounds exert
their toxic actions on microorganisms by making similar contacts
with the cells constituents. The influence of the metal is clearly vis-
ible in the antibacterial activity. This study provides a further step
in designing novel antifungal metal-based drugs.
[13] A. Mohammad, C. Varshney, S.A.A. Nami, Spectrochim. Acta, Part A 73 (2009)
20. reference therein.
Supplementary data
[14] L. Ronconi, C. Maccato, D. Barreca, R. Saini, M. Zancato, D. Fregona, Polyhedron
24 (2005) 521.
[15] O. Jung, Y.S. Sohn, J.A. Ibers, Inorg. Chem. 25 (1986) 2273.
[16] T.P. Lockhart, W.F. Manders, E.M. Holt, J. Am. Chem. Soc. 108 (1986) 6611.
[17] S. Shahzadi, S. Ali, K. Wurst, M.N. Haq, Heteroat. Chem. 18 (2007) 664.
reference therein.
CCDC 717026, 717715, 717024, and 717025 contain the supple-
mentary crystallographic data for 2, 4, 6 and 9. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.
ˇ
ˇ
[18] M. Nádvorník, J. Holecek, K. Handlír, J. Organomet. Chem. 275 (1984) 43.
[19] R. William, I. Verbruggen, M. Gielen, M. Biesemans, B. Mahieu, T.S.B. Baul,
E.R.T. Tiekink, Organometallics 17 (1998) 5758.
[20] T.S.B. Baul, S. Dhar, S.M. Pyke, E.R.T. Tiekink, E. Rivarola, R. Butcher, F.E. Smith,
J. Organomet. Chem. 633 (2001) 7.
[21] A. Tarassoli, T. Sedaghat, B. Neumüller, M. Ghassemzadeh, Inorg. Chim. Acta
318 (2001) 15.
[22] A.W. Addison, T.N. Rao, J. Reedijk, J. Van Rijn, G.C. Verschoor, J. Chem. Soc.,
Dalton Trans. (1984) 1349.
[23] G.M. Sheldrick, W.S. Sheldrick, J. Chem. Soc. A (1970) 490.
[24] G.J.M. Van der Kerk, J.G.A. Luijten, J. Appl. Chem. 6 (1956) 56.
[25] E.R.T. Tiekink, Appl. Organomet. Chem. 22 (2008) 533.
[26] R.S. Srivastava, Inorg. Chim. Acta 56 (1981) 65.
Acknowledgements
We thank the Higher Education Commission of Pakistan and the
NSERC (Canada) for financial support.
References
[1] F.W. Sunderman, Ann. Clin. Lab. Sci. 9 (1979) 1.
[2] D.L. Bodenner, P.C. Dedon, P.C. Keng, R.F. Borch, Cancer Res. 46 (1986) 2745.