Synthesis, structure, and fungicidal activity of triorganotin (4H-1, 2, 4-triazol-4-yl)benzoates

Article abstract of DOI:10.1002/hc.20566

A series of triorganotin (4H-1, 2, 4- triazol-4-yl)benzoates have been synthesized by the reaction of 4-(4H-1, 2, 4-triazol-4-yl)benzoic acid and 3-(4H-1, 2, 4-triazol-4-yl)benzoic acid with (R₃Sn)₂O (R = Et, n-Bu and Ph) or R′₃

Full text of DOI:10.1002/hc.20566

Heteroatom Chemistry
Volume 20, Number 7, 2009
Synthesis, Structure, and Fungicidal Activity of
Triorganotin (4H-1,2,4-triazol-4-yl)benzoates
Fang-Lin Li,1 Bin Dai,1 Hai-Bin Song,2 Na Mi,2 and Liang-Fu Tang2
1School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003,
Xinjiang, People’s Republic of China
2Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry,
Nankai University, Tianjin 300071, People’s Republic of China
Received 29 September 2009; revised 3 December 2009
INTRODUCTION
ABSTRACT: A series of triorganotin (4H-1,2,4-
triazol-4-yl)benzoates have been synthesized by the
reaction of 4-(4H-1,2,4-triazol-4-yl)benzoic acid and
3-(4H-1,2,4-triazol-4-yl)benzoic acid with (R3Sn)2O
(R = Et, n-Bu and Ph) or Rꢀ3SnOH (Rꢀ = p-tolyl and
cyclohexyl). The molecular structure of tri(p-tolyl)tin
3-(4H-1,2,4-triazol-4-yl)benzoate determined by X-ray
crystallography displays that the tin atom adopts a
five-coordinate distorted trigonal bipyramidal geom-
etry with the carboxyl oxygen atom and the nitro-
gen atom on 1-position of triazole ring occupying
the apical position. Moreover, this complex forms
a polymeric chain by the intermolecular Sn–N in-
teractions. All these complexes show good antifun-
gal activities in vitro against Alternaria solani, Cer-
cospora arachidicola, Gibberella zeae, Physalospora
Organotin compounds have been used widely in
industry and agriculture owing to their significant
biological activities, in spite of their toxicity and
environmental effects partially limiting their appli-
cations. Among these organotin derivatives, organ-
otin carboxylates have attracted extensive attention
because of their versatile structures [1,2] as well
as significant biological activities [3–5], especially
anticancer activity [6]. In recent years, more and
more investigations have focused on the synthesis of
organotin carboxylates of functionalized carboxylic
acids with additional O, S, or N donor groups [7–13].
Owing to the presence of additional coordinating
atoms, these organotin carboxylates show consid-
erable structural diversity. It is known that triazole
and its derivatives possess versatile biological activi-
ties, such as antimicrobial and antifungal activities.
Many triazole derivatives, for example, fluconazole
and propiconazole, have been commercially avail-
able antifungal agents. Some organotin derivatives
with triazole, such as azocyclotin (Scheme 1), have
also been used as agrochemicals. Recently, we are
interested in the synthesis and bioactivity of organ-
otin carboxylates with additional sulfur or nitrogen
donor groups, which exhibit considerable structural
diversity and good antifungal activity [14–16]. Tak-
ing into consideration of the important biological
activity of triazole derivatives as well as the versatile
coordinating ability of triazole [17], as an extension
of our investigations on biologically active organotin
ꢁ
C
piricola, and Botrytis cinerea. 2010 Wiley Periodicals,
Inc. Heteroatom Chem 20:411–417, 2009; Published online
in Wiley InterScience (www.interscience.wiley.com). DOI
10.1002/hc.20566
Correspondence to: Liang-Fu Tang; e-mail: lftang@nankai.
edu.cn.
Contract grant sponsor: National Natural Science Foundation
of China.
Contract grant number: 20721062.
2010 Wiley Periodicals, Inc.
c
ꢀ
411

412 Li et al.
Synthesis of Triethyltin 4-(4H-1,2,4-triazol-4-yl)
benzoate (3)
The mixture of 1 (0.38 g, 2 mmol) and (Et3Sn)2O
(0.43 g, 1 mmol) in anhydrous benzene (40 mL) was
stirred and was heated at reflux for 12 h. After cool-
ing to room temperature, the white solid was filtered
and was washed with n-hexane (10 mL) to give com-
pound 3. Yield: 0.51 g (65%); mp 257–258◦C. 1H
NMR (DMSO-d6, ppm): 1.10–1.28 (m, 15H, C2 H ),
5
SCHEME
1
Chemical structures of fluconazole and
7.75 (d, J = 8.0 Hz, 2H, C6 H ), 8.03 (d, J = 8.0 Hz,
4
azocyclotin.
2H, C6 H ), 9.19 (s, 2H, protons of triazole). 13C NMR
4
(DMSO-d6, ppm): 10.1 [2 J (13C-119/117Sn) = 33 Hz],
10.4 [1 J (13C-119/117Sn) = 497/475 Hz] (ethyl carbons),
120.5, 130.8, 134.4, 135.8 (C6H4), 141.2 (carbons of
triazole), 168.4 (COO). 119Sn NMR (DMSO-d6, ppm):
−25.9. IR (cm−1): νas (COO), 1621; νs (COO), 1356;
ꢀν, 265. Anal. Calcd for C15H21N3O2Sn: C, 45.72; H,
5.37; N, 10.66. Found: C, 45.92; H, 5.36; N, 10.59.
complexes, we herein report the synthesis and the
fungicidal activity in vitro of organotin (4H-1,2,4-
triazol-4-yl)benzoates.
EXPERIMENTAL
Synthesis of Tri(n-butyl)tin 4-(4H-1,2,4-triazol-
4-yl)benzoate (4)
IR spectroscopic data were obtained from a Nicolet
380 spectrometer as KBr disks. Multinuclear NMR
spectra were recorded on a Bruker 400 spectrom-
eter, and the chemical shifts were reported in
ppm with respect to reference standards (internal
This compound was obtained similarly using [(n-
C4H9)3Sn]2O instead of (Et3Sn)2O as described above
for 3. After completion of the reaction, the solvent
was removed in vacuo, and the crude product was
recrystallized from benzene to afford white solids
1
SiMe4 for H NMR and 13C NMR spectra, external
SnMe4 for 119Sn NMR). Elemental analyses were
carried out on an Elementar Vairo EL analyzer.
Melting points were measured with an X-4 digital
micro melting-point apparatus and were uncor-
rected. 4-(4H-1,2,4-Triazol-4-yl)benzoic acid (1) and
N,N-dimethylformamide azine dihydrochloride
were prepared by the published methods [18].
Organotin oxide and organotin hydroxide are com-
mercially available and are used as received without
further purification.
1
of 4. Yield: 84%; mp 193–195◦C. H NMR (CDCl3,
ppm): 0.93 (t, J = 7.0 Hz, 9H, CH ), 1.36–1.46, 1.60–
3
1.77 (m, m, 12H, 6H, CH CH CH ), 7.48 (d, J = 7.8
2
2
2
Hz, 2H, C6 H ), 8.24 (d, J = 7.8 Hz, 2H, C6 H ), 8.58
4
4
(s, 2H, protons of triazole). 13C NMR (CDCl3, ppm):
13.7, 16.9 [1 J (13C-119/117Sn) = 365/349 Hz], 27.0 [3 J
(13C-119/117Sn) = 65 Hz], 27.8 [2 J (13C-119/117Sn) =
21 Hz] (butyl carbons), 121.3, 132.3, 133.3, 136.3
(C6H4), 141.1 (carbons of triazole), 169.7 (COO).
119Sn NMR (CDCl3, ppm): 111.2. IR (cm−1): νas
(COO), 1632; νs (COO), 1355; ꢀν, 277. Anal. Calcd
for C21H33N3O2Sn: C, 52.74; H, 6.96; N, 8.79. Found:
C, 52.57; H, 7.03; N, 8.79.
Synthesis of 3-(4H-1,2,4-triazol-4-yl)benzoic
Acid (2)
The mixture of N,N-dimethylformamide azine dihy-
drochloride (10 g, 46.65 mmol) and 3-aminobenzoic
acid (6.40 g, 46.65 mmol) in benzene (125 mL) was
stirred and was heated at reflux for 7 h to yield a pale
yellow solid. After cooling to room temperature, the
solid was filtered and washed with EtOH (20 mL)
and ether (40 mL) to give compound 2 (8.45 g, 96%);
mp 292–294◦C. 1H NMR (DMSO-d6, ppm): 7.68–7.72,
Synthesis of Triphenyltin 4-(4H-1,2,4-triazol-
4-yl)benzoate (5)
This compound was obtained similarly using
(Ph3Sn)2O instead of (Et3Sn)2O as described above
for 3. Yield: 92%; mp 244–246◦C. 1H NMR
(DMSO-d6, ppm): 7.41–7.48, 7.88–7.90 (m, m, 9H,
7.97–7.80, 8.19 (m, m, s, 1H, 2H, 1H, C6 H ), 8.85 (s,
6H, C6 H ), 7.74 (d,
J
= 8.4 Hz, 2H, C6 H ),
4
5
4
br, 1H, OH), 9.24 (s, 2H, protons of triazole). 13C
NMR (DMSO-d6, ppm): 121.7, 125.6, 128.7, 130.4,
132.6, 134.2 (C6H4), 141.4 (carbons of triazole),
166.3 (COO). IR (cm−1): ν (OH), 3421 (br); ν
(C O), 1701.
7.99 (d, J = 8.4 Hz, 2H, C6 H ), 9.18 (s, 2H, pro-
4
tons of triazole). 13C NMR (DMSO-d6, ppm): 120.5,
128.3 [3 J (13C-119/117Sn) = 69 Hz], 128.9, 130.9, 133.9,
136.0, 136.2 [2 J (13C-119/117Sn) = 46 Hz], 141.2 (C6H5
and C6H4), 143.0 (carbons of triazole), 168.0 (COO).
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Structure, and Fungicidal Activity of Triorganotin (4H-1,2,4-triazol-4-yl)benzoates 413
1.35–1.45 (m, 15H, C2 H ), 7.61–7.63, 8.17, 8.23 (m,
119Sn NMR (DMSO-d6, ppm): −262.9. IR (cm−1): νas
5
s, d, J = 7.2 Hz, 2H, 1H, 1H, C6 H ), 8.63 (s, 2H,
(COO), 1629; νs (COO), 1336; ꢀν, 293. Anal. Calcd
for C27H21N3O2Sn: C, 60.26; H, 3.93; N, 7.81. Found:
C, 60.25; H, 4.00; N, 7.79.
4
protons of triazole). 13C NMR (CDCl3, ppm): 9.4 [1 J
(13C-119/117Sn) = 424/405 Hz], 10.1 [2 J (13C-119/117Sn)
= 30 Hz] (ethyl carbons), 123.4, 124.7, 130.1, 130.7,
133.2, 136.4 (C6H4), 141.3 (carbons of triazole), 169.3
(COO). 119Sn NMR (CDCl3, ppm): 54. IR (cm−1): νas
(COO), 1628; νs (COO), 1342; ꢀν, 286. Anal. Calcd
for C15H21N3O2Sn: C, 45.72; H, 5.37; N, 10.66. Found:
C, 45.92; H, 5.31; N, 10.64.
Synthesis of Tri(p-tolyl)tin 4-(4H-1,2,4-triazol-
4-yl)benzoate (6)
This compound was obtained similarly using (p-
CH3C6H4)3SnOH instead of (Et3Sn)2O as described
above for 3, but in a 1:1 molar ratio. Yield: 42%; mp
1
272–274◦C. H NMR (DMSO-d6, ppm): 2.32 (s, 9H,
Synthesis of Tri(n-butyl)tin 3-(4H-1,2,4-triazol-
CH ), 7.26 (d, J = 7.6 Hz, 6H, SnC6 H ), 7.67–7.83 (m,
3
4
4-yl)benzoate (9)
8H, SnC6 H and C6 H ), 7.95 (d, J = 7.8 Hz, 2H, C6 H ),
4
4
4
9.17 (s, 2H, protons of triazole).13C NMR (DMSO-d6,
ppm): 21.0 (CH3), 120.5, 128.9 [3 J (13C-119/117Sn) =
72 Hz], 130.8, 134.0, 135.9, 136.1 [2 J (13C-119/117Sn) =
47 Hz], 138.1, 139.4 (C6H5 and C6H4), 141.2 (car-
bons of triazole), 167.7 (COO). 119Sn NMR (DMSO-
d6, ppm): −251.2. IR (cm−1): νas (COO), 1632; νs
(COO), 1345; ꢀν, 287. Anal. Calcd for C30H27N3O2Sn:
C, 62.10; H, 4.69; N, 7.24. Found: C, 61.99; H, 4.67;
N, 7.23.
This compound was obtained similarly using [(n-
C4H9)3Sn]2O instead of (Et3Sn)2O as described above
for 8. Yield: 89%; mp 109–110◦C. H NMR (CDCl3,
1
ppm): 0.93 (t, J = 7.3 Hz, 9H, CH ), 1.37–1.45, 1.69–
3
1.71 (m, m, 12H, 6H, CH CH CH ), 7.58–7.65, 8.13,
2
2
2
8.19 (m, s, d, J = 7.3 Hz, 2H, 1H, 1H, C6 H ), 8.59
4
(s, 2H, protons of triazole). 13C NMR (CDCl3, ppm):
13.6, 17.2 [1 J (13C-119/117Sn) = 383/367 Hz], 27.0 [3 J
(13C-119/117Sn) = 67 Hz], 27.6 [2 J (13C-119/117Sn) =
22 Hz] (butyl carbons), 123.4, 124.9, 130.1, 130.5,
133.5, 135.7 (C6H4), 141.2 (carbons of triazole), 169.3
(COO). 119Sn NMR (CDCl3, ppm): 90.1. IR (cm−1): νas
(COO), 1629; νs (COO), 1349; ꢀν, 280. Anal. Calcd
for C21H33N3O2Sn: C, 52.74; H, 6.96; N, 8.79. Found:
C, 52.54; H, 7.09; N, 8.72.
Synthesis of Tricyclohexyltin 4-(4H-1,2,4-triazol-
4-yl)benzoate (7)
This compound was obtained similarly using tricy-
clohexyltin hydroxide instead of (Et3Sn)2O as de-
scribed above for 3, but in a 1:1 molar ratio. After
completion of the reaction, the solvent was removed
in vacuo, and the crude product was recrystallized
from CH2Cl2/n-hexane to afford white solids of 7.
Synthesis of Triphenyltin 3-(4H-1,2,4-triazol-
4-yl)benzoate (10)
1
Yield: 66%; mp 205–206◦C. H NMR (CDCl3, ppm):
This compound was obtained similarly using
(Ph3Sn)2O instead of (Et3Sn)2O as described above
for 8. After cooling to room temperature, the white
solid was filtered and washed with n-hexane (10 mL)
to give compound 10. Yield: 88%; mp 205–207◦C. 1H
NMR (CDCl3, ppm): 7.39–7.54, 7.77–7.92 (m, m, 9H,
1.33–1.39, 1.66–1.76, 1.98–2.03 (m, m, m, 9H, 15H,
9H, C6 H ), 7.46 (d, J = 8.4 Hz, 2H, C6 H ), 8.24
11
4
(d, J = 8.4 Hz, 2H, C6 H ), 8.55 (s, 2H, protons of
4
triazole).13C NMR (CDCl3, ppm): 26.8, 28.9 [3 J (13C-
119/117Sn) = 64 Hz], 31.1 [2 J (13C-119/117Sn) = 15 Hz],
34.1 [1 J (13C-119/117Sn) = 334/321 Hz] (C6H11), 121.3,
132.3, 133.1, 136.3 (C6H4), 141.1 (carbons of tria-
zole), 169.5 (COO). 119Sn NMR (CDCl3, ppm): 25.6.
IR (cm−1): νas (COO), 1626; νs (COO), 1353; ꢀν, 273.
Anal. Calcd for C27H39N3O2Sn: C, 58.29; H, 7.07; N,
7.55. Found: C, 58.35; H, 7.15; N, 7.51.
6H, C6 H ), 7.33, 8.04, 8.18 (s, s, d, J = 7.7 Hz, 2H, 1H,
5
1H, C6 H ), 8.32 (s, 2H, protons of triazole). 13C NMR
4
(CDCl3, ppm): 123.9, 125.5, 128.3, 129.1 [3 J (13C-
119/117Sn) = 65 Hz], 130.3, 130.9, 133.6, 134.2, 136.9
[2 J (13C-119/117Sn) = 47 Hz], 138.5 (C6H5 and C6H4),
141.4 (carbons of triazole), 170.2 (COO). 119Sn NMR
(CDCl3, ppm): −126.8. IR (cm−1): νas (COO), 1647; νs
(COO), 1345; ꢀν, 302. Anal. Calcd for C27H21N3O2Sn:
C, 60.26; H, 3.93; N, 7.81. Found: C, 60.21; H, 3.95;
N, 7.66.
Synthesis of Triethyltin 3-(4H-1,2,4-triazol-4-yl)
benzoate (8)
The mixture of 2 (0.38 g, 2 mmol) and (Et3Sn)2O
(0.43 g, 1 mmol) in anhydrous benzene (40 mL) was
stirred and was heated at reflux for 12 h. After cool-
ing to room temperature, the solvent was removed in
vacuo, and the crude product was recrystallized from
benzene/n-hexane to afford white solids of 8. Yield:
0.61 g (77%); mp 178–179 ◦C. 1H NMR (CDCl3, ppm):
Synthesis of Tri(p-tolyl)tin 3-(4H-1,2,4-triazol-
4-yl)benzoate (11)
This compound was obtained similarly using
(p-CH3C6H4)3SnOH instead of (Et3Sn)2O as
Heteroatom Chemistry DOI 10.1002/hc

414 Li et al.
TABLE 1 Crystallographic Data for Compound 11
described above for 8, but in a 1:1 molar ratio.
After cooling to room temperature, the white solid
was filtered and washed with n-hexane (10 mL) to
Formula
C30H27N3O2Sn
1
give compound 11. Yield: 44%; mp 261–262◦C. H
Formula weigh
Crystal size (mm)
Crystal system
Space group
580.24
0.20 × 0.18 × 0.12
Orthorhombic
P212121
NMR (DMSO-d6, ppm): 2.32 (s, 9H, CH ), 7.24–7.28,
3
7.62–7.94 (m, m, 5H, 11H, SnC6 H and C6 H ),
4
4
9.15 (s, 2H, protons of triazole). 13C NMR (DMSO-
d6, ppm): 21.0 (CH3), 121.8, 125.4, 128.7, 128.9 [3 J
(13C-119/117Sn) = 71 Hz], 130.2, 133.9, 134.1, 136.1
[2 J (13C-119/117Sn) = 48 Hz], 138.1, 139.4 (C6H5 and
C6H4), 141.5 (carbons of triazole), 166.6 (COO).
119Sn NMR (DMSO-d6, ppm): −251.3 ppm. IR
(cm−1): νas (COO), 1638; νs (COO), 1346; ꢀν, 292.
Anal. Calcd for C30H27N3O2Sn: C, 62.10; H, 4.69; N,
7.24. Found: C, 61.95; H, 4.79; N, 7.24.
˚
a (A)
9.4679(19)
16.487(3)
˚
b (A)
˚
c (A)
17.475(4)
113(2)
T (K)
˚
λ (A)
0.71073
2727.7(9)
1.413
3.40–50.02
0.967
3
˚
V (A )
Dcalc. (g cm−3
)
2θ Range (◦)
Absorption coefficient (mm−1
)
Z
4
F(000)
Reflections collected
Independent reflections (Rint
No. of observed reflections (I > 2σ(I )) 4738
1176
21511
4818 (0.0290)
Synthesis of Tricyclohexyltin 3-(4H-1,2,4-triazol-
4-yl)benzoate (12)
)
No. of parameters
Residuals R, R w [I > 2σ(I )]
Goodness-of-fit
327
This compound was obtained similarly using tricy-
clohexyltin hydroxide instead of (Et3Sn)2O as de-
scribed above for 8, but in a 1:1 molar ratio. After the
solvent was removed in vacuo, the crude product was
recrystallized from CH2Cl2/n-hexane to afford white
0.0176, 0.0452
1.106
RESULTS AND DISCUSSION
1
solids of 12. Yield: 68%; mp 118–120◦C. H NMR
Synthesis and Characterization of Complexes
(CDCl3, ppm): 1.33–1.39, 1.65–1.72, 1.93–2.03 (m, m,
m, 9H, 15H, 9H, C6 H ), 7.53–7.63, 8.09, 8.18 (m, s, d,
11
3-(4H-1,2,4-Triazol-4-yl)benzoic acid (2) was syn-
thesized similarly using 3-aminobenzoic acid in-
stead of 4-aminobenzoic acid as described in the
preparation of 4-(4H-1,2,4-triazol-4-yl)benzoic acid
(1) [18]. Upon treatment of these two acids with
organotin oxide or organotin hydroxide in anhy-
drous benzene, a series of triorganotin (4H-1,2,4-
triazol-4-yl)benzoates were obtained (Scheme 2),
which have been characterized by IR and NMR (1H,
13C, and 119Sn) spectra as well as elemental analyses.
J = 7.7 Hz, 2H, 1H, 1H, C6 H ), 8.54 (s, 2H, protons of
4
triazole).13C NMR (CDCl3, ppm): 26.8, 28.8 [3 J (13C-
119/117Sn) = 64 Hz], 31.1 [2 J (13C-119/117Sn) = 15 Hz],
33.8 [1 J (13C-119/117Sn) = 312/303 Hz] (C6H11), 123.6,
125.1, 130.1, 130.6, 133.8, 135.0 (C6H4), 141.3 (car-
bons of triazole), 169.3 (COO). 119Sn NMR (CDCl3,
ppm): 29.3. IR (cm−1): νas (COO), 1640; νs (COO),
1331; ꢀν, 309. Anal. Calcd for C27H39N3O2Sn: C,
58.29; H, 7.07; N, 7.55. Found: C, 58.45; H, 7.05;
N, 7.59.
IR Spectra. Compared to those of the free
acids, the remarkable changes in the IR spectra
of complexes 3–12 are the absence of the broad
band ascribed to the COOH group as well as the
lower carbonyl stretching frequencies, indicating the
Crystal Structure Determination of 11
Crystals of 11 suitable for X-ray analyses were ob-
tained by slowly cooling the hot ethanol/n-hexane
solution of 11. Intensity data were collected on a
Rigaku Saturn CCD detector using the ω/2θ scan
technique, and a semiempirical absorption correc-
tion was applied. The structure was solved by direct
methods and was refined by full-matrix least squares
on F2. All non-hydrogen atoms were refined with
anisotropic displacement parameters. A summary
of the fundamental crystal data is listed in Table 1.
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre (CCDC) as
CDCC No. 749359. These data can be obtained free of
charge from the CCDC at: www.ccdc.cam.ac.uk/data
request/cif.
SCHEME 2 Synthesis of triorganotin (4H-1,2,4-triazol-4-
yl)benzoates.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Structure, and Fungicidal Activity of Triorganotin (4H-1,2,4-triazol-4-yl)benzoates 415
deprotonation of the carboxylic acids and the car-
boxylate coordination [19]. The differences (ꢀν) be-
tween asymmetric and symmetric stretching vibra-
tions of the carboxylate groups are observed in the
region of 265–309 cm−1 in these complexes, larger
than those detected in the corresponding sodium
salts of acids 1 (217 cm−1) and 2 (224 cm−1), in which
the asymmetric and symmetric stretching vibrations
of the carboxylate groups appear at 1605 and 1388
cm−1 for 1, and 1618 and 1394 cm−1 for 2, respec-
tively, implying the monodentate manner of the car-
boxylate groups in these complexes to the tin atom
[20].
FIGURE 1 Polymeric chain structure of 11 with the ther-
mal ellipsoids at the 30% probability level. Hydrogen atoms
˚
are omitted for clarity. Selected bond distances (A) and
angles (◦): Sn1–C10 2.130(2), Sn1–C17 2.131(2), Sn1–
C24 2.126(2), Sn1–N1 2.4509(18), Sn1–O1A 2.1518(15),
NMR Spectra. The NMR spectroscopic data
˚
Sn1· · ·O2A 3.269(2), C9–O1 1.295(3), C9–O2 1.221(3) A;
1
also support the suggested structures. The H NMR
N1–Sn1–O1A 175.74(6), C10–Sn1–C17 121.05(9), C10–
Sn1–C24 120.04(8), C17–Sn1–C24 117.95(9), C7–C9–O1
113.26(19), C7–C9–O2 121.0(2), O1–C9–O2 125.7(2), Sn1–
O1A–C9A 122.46(13)◦. Symmetric operations: A = − x +
1.5, − y, z + 0.5.
spectra display the expected integration values and
peak multiplicities. The 13C NMR spectra clearly
show the carbonyl carbon resonances at 168.4–
170.2 ppm, slightly downfield shift compared with
those in free acids 1 and 2. Holecˇek and coworkers
1
have shown that the J(13C–119/117Sn) coupling con-
bidentate ligand by the carboxylate oxygen atom and
1-position nitrogen atom of triazole, which results
in the formation of a linkage coordination polymer
through the intermolecular Sn–N interactions. The
tin atom adopts a five-coordinate slightly distorted
trigonal bipyramidal geometry. The electronegative
nitrogen and oxygen atoms occupy the apical po-
sitions with an angle N1–Sn1–O1A of 175.74(6)◦,
and three p-tolyl groups lie in the equatorial plane.
stants depend significantly on the coordination num-
ber of the tin atom in triorganotin complexes [21,22].
For example, the 1 J(13C–119/117Sn) coupling constants
for four-coordinated tributyltin complexes in CDCl3
solution exhibit the values of 326–390 Hz [22]. In
the present work, the 1 J (13C-119/117Sn) coupling
constants of tributyltin complexes 4 (365/349 Hz)
and 9 (383/367 Hz) in CDCl3 solution are in accor-
dance with the values for four-coordinate tributyltin
complexes. The estimated C–Sn–C angles (∼111◦ in
4 and ∼113◦ in 9, respectively) calculated from their
1 J (13C–119Sn) coupling constants in solution [23]
are also consistent with the tetrahedral tin atom. In
addition, the 119Sn NMR resonances of complexes
in CDCl3 solution also suggest the four-coordinated
tetrahedral geometry of the tin atom. The 119Sn
NMR chemical shifts of tributyltin complexes 4
(111.2 ppm) and 9 (90.1 ppm) and triphenyltin com-
plex 10 (−126.8 ppm) are compared to those values
reported in the corresponding four-coordinated
tributyltin (100–145 ppm) and triphenyltin (−83 to
−122 ppm) carboxylates [2]. It is worthy of note
that although these complexes possibly exhibit poly-
meric linkage structures in solid (one case shown in
Fig. 1), these complexes should be monomeric four
coordinated structures in noncoordinating solvent,
based on the above results. The polymeric structures
lost in solution possibly owing to the weak Sn · · · N
interactions.
˚
The Sn1–N1 distance is 2.4509(18) A, slightly shorter
than those in linkage polymeric triaryltin derivatives
with nitrogen-functionalized carboxylate ligands,
˚
such as [2-(4-PyCH2S)]C6H4CO2SnPh3 (2.524(2) A)
[15], but similar to those in organotin deriva-
tives with triazole ligands, such as CH2Tz2SnPh2Br2
˚
(2.454(7) A, Tz: 1,2,4-triazol-1-yl) [24]. The non-
˚
bond Sn1 · · · O2A distance is 3.269(2) A, markedly
longer than the covalent Sn1–O1A bond distance
˚
(2.1518(15) A), but still shorter than the sum of
the van der Waal’s radii for the Sn and O atoms of
˚
3.57 A [25], suggesting that some weak interactions
possibly exist between these two atoms. The tria-
zolyl plane and the phenyl plane formed by the C3–
C8 atoms are noncoplanar, and the dihedral angle
between them is 140.6◦.
Fungicidal Activity
Preliminary in vitro tests for fungicidal activity of
all compounds have been carried out by the fungi
growth inhibition method [26]. The data are summa-
rized in Table 2, which indicate that all compounds
involving in complexes 3–12 as well as the free acids
The Crystal Structure of Complex 11
The molecular structure of 11 is presented in Fig. 1.
3-(4H-1,2,4-Triazol-4-yl)benzoate acts as a bridging
Heteroatom Chemistry DOI 10.1002/hc

416 Li et al.
TABLE 2 Antifungal Activity Data of the Free Acid Ligand and Complexes (Percent Inhibition)a
Compound
Alternaria solani Cercospora arachidicola Gibberella zeae Physalospora piricola Botrytis cinerea
1
2
3
4
5
6
7
8
9
10
11
12
22.2
27.8
100.0
100.0
83.3
66.7
66.7
100.0
100.0
83.3
72.2
66.7
26.1
30.4
78.3
91.3
82.6
56.5
82.6
69.6
69.6
82.8
78.3
82.6
91.3
32.1
32.1
100.0
100.0
71.7
60.4
77.4
100.0
100.0
71.7
60.4
67.9
50.0
54.8
100.0
98.8
94.1
95.2
95.0
95.0
100.0
100.0
95.0
100.0
95.0
100.0
100.0
85.0
78.6
100.0
100.0
73.8
78.6
96.4
95.0
100.0
100.0
Positive controlb
88.9
94.3
100.0
aConcentration: 50 μg/mL of DMF.
bPositive control: propiconazole.
1 and 2 display high activities to Botrytis cinere.
Compared with free acids 1 and 2, their complexes
3–12 are more active for Alternaria solani, Cercospora
arachidicola, Gibberella zeae, and Physalospora piri-
cola, possibly due to the increased lipophilic na-
ture, led by the complexation with organotin moi-
ety, which strengthens the interactions of complexes
with the cells [27]. Moreover, the inhibition per-
centage of triethyltin and tributyltin complexes in
vitro for Alternaria solani, Gibberella zeae, and Physa-
lospora piricola are approximate to 100%, respec-
tively, and higher than the corresponding values
of triaryl and tricyclohexyltin complexes, in accor-
dance with high toxicity of trialkyltin derivatives
[28]. It is worthy of note that the tributyltin deriva-
tive 4 of acid 1 is more active against Cercospora
arachidicola than the corresponding derivative 9 of
acid 2. In addition, the derivatives 5 and 6 of acid 1
also show high activities against Physalospora piri-
cola than the corresponding derivatives 10 and 11 of
acid 2. However, the activity of derivative 7 of acid
1 against Physalospora piricola is lower than that
of derivative 12 of acid 2. Even though no remark-
able rules are found so far, the differences between
para- and meta-substitution may inspire further
investigations.
tributyltin complexes, show good antifungal activi-
ties in vitro.
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