Synthesis, characterization, and biological evaluation of novel ferrocene-triadimefon analogues

Article abstract of DOI:10.1016/j.jorganchem.2005.11.029

In order to improve biological behavior of the 1H-1,2,4-triazole derivatives, a series of new ferrocene-analogues of commercial triadimefon were synthesized and their antifungal and plant growth regulatory activities evaluated. These organometallic analogues showed lower antifungal activity than parent triadimefon, but exhibited promising plant growth regulatory activity.

Full text of DOI:10.1016/j.jorganchem.2005.11.029

Journal of Organometallic Chemistry 691 (2006) 2340–2345
www.elsevier.com/locate/jorganchem
Synthesis, characterization, and biological evaluation
of novel ferrocene-triadimefon analogues
a
a
a
a
a
Zhong Jin , Yan Hu , Aihong Huo , Weifeng Tao , Ling Shao ,
a
a,b,
*
Jianbing Liu , Jianxin Fang
a
Institute of Elemento-Ogranic Chemistry, Nankai University, Weijin Road 94#, Tianjin 300071, PR China
b
State Key Laboratory of Elemento-Ogranic Chemistry, Nankai University, Tianjin 300071, PR China
Received 30 July 2005; received in revised form 10 November 2005; accepted 15 November 2005
Abstract
In order to improve biological behavior of the 1H-1,2,4-triazole derivatives, a series of new ferrocene-analogues of commercial
triadimefon were synthesized and their antifungal and plant growth regulatory activities evaluated. These organometallic analogues
showed lower antifungal activity than parent triadimefon, but exhibited promising plant growth regulatory activity.
ꢀ 2005 Published by Elsevier B.V.
Keywords: Ferrocene; Triadimefon; Antifungal activity; Plant growth regulatory activity
1. Introduction
dent 14a-sterol demethylase (P450DM), an important
enzyme in ergosterol biosynthesis in fungi and cholesterol
synthesis in mammalian cells [5].
Nowadays, invasive fungal infections, ranking alongside
bacterial infections, have become a major cause of morbid-
ity and mortality in seriously debilitated and immunocom-
promised patients [1]. Relatively, seriously insuppressible
mildews and rusts have arose from invasive fungal infec-
tions on all kinds of agricultural and horticultural species
[2]. 1H-1,2,4-Triazole derivatives (Chart 1), such as agro-
chemicals triadimefon (1), triadimenol (2), flusilazole, bit-
ertanol, cyproconazole, etc. [3] and clinical drugs
fluconazole (3) and itraconazole (4) [4], are a class of bio-
logically significant compounds which were widely used
as antifungal agents against mildews and rusts of cereal
grains, fruits, vegetables, and ornamentals, or clinically
against topical or disseminated Candida spp. and Aspergil-
lus spp. These compounds inhibit fungal proliferation by
their interference with steroid biosynthesis and fungal
cell-wall formation mediated by cytochrome P450-depen-
However, with extensive application in agriculture and
horticulture, triadimefon and triadimenol are suspected of
having teratogenic potential such as craniofacial and axial
skeletal defects on the basis of developmental toxicity stud-
ies on rodent mammals [6]. It has also been ascertained that
triadimefon and triadimenol can produce a neurotoxic syn-
drome in rats characterized by increased motor activity, ste-
reotyped behaviors, and altered monoamine metabolism
due to inhibition of dopamine uptake [7]. And besides, tria-
dimefon had a significant stimulating side effect on respira-
tion at a concentration of 1–100 mg/kg and on inhibition of
nitrification in soil at a concentration of 100 mg/kg [8].
Although few data are available on the effect of agrochem-
ical triazoles on human pregnancy, the effect of the clinical
drug fluconazole on newborns has been well documented.
Long-term or high-dose maternal fluconazole therapy is
probably related to an increased teratological risk, reported
craniofacial and limb abnormalities in newborns [9].
Recently, increasing interests have been focused on
developing structural variations of established drugs by
*
Corresponding author. Tel.: +86 22 2350 5330; fax: +86 22 2350 3438.
E-mail addresses: zjin@nankai.edu.cn (Z. Jin), fjx@nankai.edu.cn (J.
Fang).
0022-328X/$ - see front matter ꢀ 2005 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2005.11.029

Z. Jin et al. / Journal of Organometallic Chemistry 691 (2006) 2340–2345
2341
O
OH
F
OH
N
H3C
H3C
H3C
H3C
O
N
O
N
N
N
CH3
N
CH3
N
N
N
Cl
N
Cl
N
F
N
N
1
2
3
Fluconazole
Triadimefon
Triadimenol
N
N
O
N
Cl
N
N
N
N
O
O
O
4
Itraconazole
Cl
Chart 1.
metallocenic organometallic compounds as alternatives of
the chemotherapy of drug-resistance in cancer and tropical
diseases [10]. The stability, non-toxicity and readily mem-
brane-permeation of the ferrocenyl group, the accessibility
of a large variety of derivatives, as well as its favorable elec-
trochemical properties have made ferrocene and its deriva-
tives very suitable for biological applications and for
conjugation with biomolecules [11]. Several structural
modification of established drugs with ferrocenyl moiety
have been reported, such as ferrocene fluconazole [12], fer-
rocene aspirin [13], the anti-malarial drugs chloroquine
(termed ferroquine), quinine, mefloquine, and artemisinin
[14], and the anti-cancer drug tamixofen (termed ferroci-
fen) [15].
reported their chemistry and biological screening results
involving antifungal and plant growth regulatory activity.
2. Results and discussion
2.1. Synthesis of ferrocene-triadimefon analogues
As shown in Scheme 1, our synthesis of the title com-
pounds 10a–j was started from commercial ferrocene 5.
The intermediates, acetylferrocene (6), a-bromoacetylferro-
cene (7), and a-(1H-1,2,4-triazol-1-yl)acetylferrocene (8)
were prepared according to the previous literaturesÕ meth-
ods in a yield of 93%, 80%, and 95%, respectively [16–18].
Attempt to direct bromination of a-(1H-1,2,4-triazol-1-
yl)acetylferrocene (8) under conventional conditions, such
as Br2/HOAc, NBS in CH3CN or CS2, NBS/azobis(isobu-
tyronitrile) (AIBN), and etc., caused a decomposed mixture
of original materials. Thus, the key intermediate 9 was pre-
pared utilizing similar bromination method described by
Tarraga and co-workers [17].
As part of our continual program in pursuit of novel
biological molecules containing 1H-1,2,4-triazole moiety,
a class of novel triadimefon analogues 10a–j structurally
modified by ferrocenyl group was designed and synthesized
for improving biological behavior (Chart 2). We herein
Originally, substitution reactions of bromide 9 by vari-
ous phenols were conducted utilizing sodium hydride as
base in anhydrous tetrahydrofuran (THF), and low yields
were reached because of insolubility of sodium phenoxyl
in THF. Thus, anhydrous potassium carbonate was used
as base instead of sodium hydride and reactions were car-
ried out in anhydrous acetonitrile under elevated tempera-
ture. After conventional workup, the target ferrocene-
O
O
H3C
H3C
O
N
O
N
X
Fe
CH3
N
N
Cl
N
N
Ferrocene-Triadimefon
Triadimefon
Chart 2.
O
1. LDA/THF
2. TMSCl
3. NBS
O
O
N
N
1H-1,2,4-triazole
K2CO3
CH2Br
N
AcCl/AlCl3
ref. 16
CH3
Fe
Fe
Fe
Fe
ref. 17
ref. 18
8
5
6
7
OH
O
O
N
1. LDA/THF
O
N
2. TMSCl
3. NBS
X
N
X
Fe
N
N
Br
Fe
N
K2CO3
72%
9
10a-j
Scheme 1.

2342
Z. Jin et al. / Journal of Organometallic Chemistry 691 (2006) 2340–2345
triadimefon analogues 10a–j were readily obtained in good
to excellent yields.
tuted aryl group was spatially repulsed and swerved to
nearby triazole group.
2.2. Single crystalline X-ray diffraction analysis of ferrocene-
triadimefon analogues
2.3. Biological evaluation
2.3.1. Antifungal activity
To confirm their structures and explore steady confor-
mation of this type of ferrocene-triadimefon derivatives,
the structure of compound 10f was investigated by a single
crystalline X-ray diffraction analysis (Fig. 1). In the crystal
cell, due to the bulkiness of ferrocenyl group, the substi-
Compounds 10a–j were assayed for antifungal activities
against mildew and rusts on intravital wheat plants, includ-
ing five selected fungi Isariopsis clavispora, Bremia lactucae,
Cladosporium fulvum, Erysiphe graminis, and Alternaria
mali, according to procedures described previously [19].
The screening results were outlined in Table 1.
To our disappointment, all the tested compounds
showed lower antifungal activity against all fungi than par-
ent triadimefon. As far as we know, a linkage between the
triazole ring and substituted aryl group via no more than
two atoms is essential for their fungicidal activity. Besides,
we have proved that an extended backbone linking the tri-
azole group and aryl group in an almost linear fashion pos-
sesses higher antifungal activity than a distorted backbone
[20]. It is the bulkiness of ferrocenyl group that make a dis-
torted backbone linking the triazole group and aryl group
adopted. In addition, it is well known that the antifungal
activities of the triazole derivatives are related to their
interference with steroid biosynthesis and fungal cell-wall
formation mediated by ferrous cytochrome-P450 enzymes
[5]. It was also hypothesized that binding of the triazole
to ferrous atom of cytochrome-P450 enzymes was replaced
with binding of the triazole to ferrous atom of ferrocene
group by intramolecular or intermolecular interaction, as
a result, the antifungal activities of title compounds 10a–j
was depressed.
Fig. 1. Molecular structure and crystallographic numbering scheme for
compound 10f (Hydrogen atoms were omitted for clarification). Selected
˚
bond lengths (A): Fe1–C1 2.028(2); Fe1–C2 2.027(2); Fe1–C5 2.043(2);
Fe1–C6 2.042(2); C1–C11 1.450(3); O1–C11 1.211(3); O2–C12 1.413(3);
O2–C13 1.383(3): C11–C12 1.543(3); N1–C12 1.441(3); N1–N2 1.356(3);
N3–C19 1.314(3); N2–C20 1.313(3); N3–C19 1.314(3); N3–20 1.342(4).
Selected bond angles (ꢁ): C2–Fe1–C1 41.41(9); C2–Fe1–C7 108.28(11);
C1–Fe1–C7 122.39(10); C2–Fe1–C8 120.97(11); C7–Fe1–C8 40.35(10);
C5–C1–C2 107.5(2); C5–C1–C11 124.7(2); C2–C1–C11 127.4(2); C13–O2–
C12 118.13(17); C19–N1–N2 109.6(2); C19–N1–C12 130.9(2); N3–C19–
N1 110.5(2); N2–C20–N3 115.8(2).
2.3.2. Plant growth regulatory activity
Plant growth regulatory activities of new ferrocene-
triadimefon derivatives 10a–j were tested using cucumber
cotyledon rhizogenesis method (see Section 4.3.). The plant
growth regulatory activity data for compounds 10a–j were
shown in Table 1.
Table 1
Antifungal and plant growth regulatory activity of compounds 10a–j
Compound
Substituted X
Antifungal activity (relative inhibitory ratio, %)a
Plant growth regulatory activity (%)b
I. clavispora
B. lactucae
C. fulvum
E. graminis
A. mali
10a
10b
4-Cl
2,4-Cl2
2,5-Cl2
15.6
15.6
15.6
15.6
15.6
23.3
23.3
15.6
15.6
15.6
92.8
26.7
26.7
26.7
26.7
26.7
26.7
33.3
26.7
33.3
26.7
76.2
13.0
13.0
0
0
13.0
0
13.0
13.0
0
0
42.8
11.9
14.3
11.9
11.9
11.9
16.6
16.6
11.9
14.3
11.9
56.6
20.0
20.0
30.0
20.0
20.0
20.0
30.0
20.0
30.0
20.0
96.6
+60.0
+50.0
+40.0
+40.0
+16.6
+68.1
+16.3
+93.9
+76.7
+98.2
+57.1
10c
10d
2,4,5-Cl3
2,4,6-Cl3
4-NO2
3-CH3-6-Cl
2,4-Br2
1-Naphthoxy
2-Naphthoxy
–
10e
10f
10g
10h
10i
10j
Triadimefon
a
Antifungal activity was assayed on intravital wheat plants at a concentration of 50 mg/L.
Plant growth regulatory activity was assayed using cucumber cotyledon rhizogenesis method at a concentration of 10 mg/L.
b

Z. Jin et al. / Journal of Organometallic Chemistry 691 (2006) 2340–2345
2343
To our surprise, although these novel triadimefon ana-
logues exhibited lower antifungal activities against various
fungi than parent triadimefon, screening data displayed
that all of them had excellent plant growth regulatory
activity. The target compounds 10a–j obvious promoted
cotyledon rhizogenesis of cucumber seed at a concentration
of 10 mg/L. In comparison with parent triadimefon, com-
pounds 10e and 10g showed lower activity than the parent
triadimefon, the ferrocenee analogue 10a, 10f and 10i had a
comparative activity while compounds 10h and 10j dis-
played more highly promoting activity.
With respect to ineffective antifungal activity and prom-
ising plant growth regulatory activity of these ferrocene-
triadimefon derivatives, it could be inferred that these
triazole derivatives might share different action mechanism
between fungicidal activity and plant growth regulator
activity. However, to prove this possibility, further chemi-
cal and biological investigation is needed to clarify action
modes of these novel ferrocene-triadimefon analogues.
another 4 h at ꢀ78 ꢁC and N-bromosuccinimide (57 mmol)
was added in small portions. The cool bath was then
removed and the reaction was not quenched until room
temperature was reached. After conventional workup and
separation by flash column chromatography, 2-bromo-2-
(1H-1,2,4-triazol-1-yl)acetylferrocene (9) was obtained as
deep red crystal in 72.7% yield, m.p. 114–116 ꢁC (after
recrystallization from acetone-petroleum ether (V/V 1:1)),
1H NMR d (300 MHz, d6-DMSO): 8.24 (1H, s, C30, tria-
zole), 8.08 (1H, s, C50, triazole), 6.48 (1H, s, CHBr), 4.30
(2H, s, metallocene), 4.22 (2H, s, metallocene), 4.14 (5H,
s, metallocene); EIMS (M+) m/z: 373. Anal. Calc. for
C14H12BrFeN3O: C 44.96, H 3.23, N 11.23. Found: C
44.70, H 3.19, N 11.10%.
4.2. General procedure for synthesis of 2-aryloxy-1-
ferrocenyl-2-(1H-1,2,4-triazol-1-yl)ethanones (10a–j)
To a suspension solution of 2-bromo-2-(1H-1,2,4-tria-
zol-1-yl)acetylferrocene (9) (2.7 mmol) and anhydrous
potassium carbonate (2.835 mmol) in dry acetonitrile
(10 mL) was added substituted phenols (2.835 mmol) in
one portion at room temperature. The mixture was stirred
and warmed to reflux for 2 h. The cooled mixture was run
into a 10% aqueous NaOH solution (50 mL) and resulting
precipitate was collected by filtration. Recrystallization
from ethyl acetate-petroleum ether (v/v 1:1) gave title
compounds, 2-aryloxy-1-ferrocenyl-2-(1H-1,2,4-triazol-1-yl)
ethanone derivatives (10a–j).
3. Conclusion
In search of potentially biological molecules containing
1H-1,2,4-triazole moiety, a series of new ferrocene-
triadimefon analogues were synthesized and their anti-
fungal and plant growth regulatory activity assayed. These
ferrocenyl-substituted derivatives showed lower antifungal
activity than parent triadimefon, while exhibited unexpect-
edly promising plant growth regulatory activity.
4. Experimental
4.2.1. 2-(4-Chlorophenoxy)-1-ferrocenyl-2-(1H-1,2,4-
triazol-1-yl)ethanone (10a)
1
All reactions were carried out under nitrogen atmo-
sphere and monitored by conventional TLC method.
THF was distilled on CaH2 and acetonitrile was distilled
on anhydrous CaCl2 prior to use. All melting points were
determined on a Taike hotplate melting apparatus and
Orange yellow solid; yield 88.1%; m.p. 165–167 ꢁC; H
NMR d(300 MHz, d6-DMSO): 9.00 (1H, s, C30, triazole),
8.18 (1H, s, C50, triazole), 7.48–7.23 (4H, m, aryl), 7.42
(1H, s, CHTr), 4.97 (2H, s, metallocene), 4.86 (1H, s,
metallocene), 4.77 (1H, s, metallocene), 4.30 (5H, s, metal-
locene); EIMS (M+) m/z: 422. Anal. Calc. for
C20H16ClFeN3O2: C 56.97, H 3.82, N 9.97. Found: C
56.88, H 3.79, N 10.02%.
1
thermometer was uncorrected. The H NMR spectra were
measured on a Bruker Ultra-300 spectrometer in d6-DMSO
solution with TMS as internal standard. Elemental analy-
ses were determined on an MT-3 elemental analyzer within
5& of the theoretical values. Mass spectra were recorded
on a HP-5988A GC–MS instrument at 70 eV, and the
temperature of ionization was 200 ꢁC. Acetylferrocene
(6), a-bromoacetylferrocene (7), and a-(1H-1,2,4-triazol-
1-yl)acetylferrocene (8) were prepared according to the
literaturesÕ methods in a yield of 93%, 80%, and 95%,
respectively [16–18].
4.2.2. 2-(2,4-Dichlorophenoxy)-1-ferrocenyl-2-(1H-1,2,4-
triazol-1-yl)ethanone (10b)
Red solid; yield 86.6%; m.p. 151–152 ꢁC; 1H NMR
d(300 MHz, d6-DMSO): 8.94 (1H, s, C30, triazole), 8.18
(1H, s, C50, triazole), 7.71–7.32 (3H, m, aryl), 7.50 (1H,
s, CHTr), 5.01 (1H, s, metallocene), 4.92 (1H, s, metallo-
cene), 4.88 (1H, s, metallocene), 4.74 (1H, s, metallocene),
4.29 (5H, s, metallocene); EIMS (M+) m/z: 456. Anal. Calc.
for C20H15Cl2FeN3O2: C 52.67, H 3.31, N 9.21. Found: C
52.78, H 3.48, N 9.41%.
4.1. 2-Bromo-2-(1H-1,2,4-triazol-1-yl)acetylferrocene (9)
To a well stirred LDA (72.3 mmol) solution in THF
(20 mL) was dropwise added a solution of a-(1H-1,2,4-tria-
zol-1-yl)acetylferrocene (8) in THF (20 mL) at ꢀ78 ꢁC dur-
ing a period of 30 min. After stirred at that temperature for
2 h, trimethylchlorosilane (57 mmol) was run into the mix-
ture in one portion. The reaction mixture was stirred for
4.2.3. 2-(2,5-Dichlorophenoxy)-1-ferrocenyl-2-(1H-1,2,4-
triazol-1-yl)ethanone (10c)
Deep red solid; yield 63.0%; m.p. 173–175 ꢁC; 1H NMR
d(300 MHz, d6-DMSO): 9.19 (1H, s, C30, triazole), 8.25
(1H, s, C50, triazole), 7.71–6.46 (3H, m, aryl), 7.57 (1H,

2344
Z. Jin et al. / Journal of Organometallic Chemistry 691 (2006) 2340–2345
s, CHTr), 5.02 (1H, s, metallocene), 4.93 (1H, s, metallo-
cene), 4.89 (1H, s, metallocene), 4.75 (1H, s, metallocene),
4.31 (5H, s, metallocene); EIMS (M+) m/z: 456. Anal. Calc.
for C20H15Cl2FeN3O2: C 52.67, H 3.31, N 9.21. Found: C
52.69, H 3.38, N 9.35%.
for C20H15Br2FeN3O2: C 44.08, H 2.77, N 7.71. Found: C
44.07, H 2.66, N 7.61%.
4.2.9. 2-(1-Naphthenoxy)-1-ferrocenyl-2-(1H-1,2,4-triazol-
1-yl)ethanone (10i)
Red solid; yield 82.0%; m.p. 173–175 ꢁC; 1H NMR
d(300 MHz, d6-DMSO): 9.03 (1H, s, C30, triazole), 8.19
(1H, s, C50, triazole), 7.94–7.39 (7H, m, aryl), 7.92 (1H,
s, CHTr), 4.96 (2H, s, metallocene), 4.75 (2H, s, metallo-
cene), 4.30 (5H, s, metallocene); EIMS (M+) m/z: 437.
Anal. Calc. for C24H19FeN3O2: C 65.92, H 4.38, N 9.61.
Found: C 65.91, H 4.39, N 9.70%.
4.2.4. 2-(2,4,5-Trichlorophenoxy)-1-ferrocenyl-2-(1H-
1,2,4-triazol-1-yl)ethanone (10d)
1
Yellow solid; yield 81.3%; m.p. 175–177 ꢁC; H NMR
d(300 MHz, d6-DMSO): 8.95 (1H, s, C30, triazole), 8.18
(1H, s, C50, triazole), 7.95 (1H, s, aryl), 7.78 (1H, s, aryl),
7.67 (1H, s, CHTr), 5.00 (1H, s, metallocene), 4.92 (1H,
s, metallocene), 4.75 (2H, s, metallocene), 4.30 (5H, s,
metallocene); EIMS (M+) m/z: 490. Anal. Calc. for
C20H14Cl3FeN3O2: C 48.97, H 2.88, N 8.57. Found: C
49.09, H 3.04, N 8.73%.
4.2.10. 2-(2-Naphthenoxy)-1-ferrocenyl-2-(1H-1,2,4-
triazol-1-yl)ethanone (10j)
Purple red solid; yield 81.6%; m.p. 152–154 ꢁC; 1H
NMR d(300 MHz, d6-DMSO): 8.95 (1H, s, C30, triazole),
8.16 (1H, s, C50, triazole), 7.97–7.40 (7H, m, aryl), 7.70
(1H, s, CHTr), 4.99 (2H, s, metallocene), 4.77 (2H, s,
metallocene), 4.30 (5H, s, metallocene); EIMS (M+) m/z:
437. Anal. Calc. for C24H19FeN3O2: C 65.92, H 4.38, N
9.61. Found: C 65.90, H 4.37, N 9.74%.
4.2.5. 2-(2,4,6-Trichlorophenoxy)-1-ferrocenyl-2-(1H-
1,2,4-triazol-1-yl)ethanone (10e)
1
Orange yellow solid; yield 80.5%; m.p. 196–198 ꢁC; H
NMR d(300 MHz, d6-DMSO): 8.85 (1H, s, C30, triazole),
8.15 (1H, s, C50, triazole), 7.81 (2H, s, aryl), 7.20 (1H, s,
CHTr), 5.03 (1H, s, metallocene), 4.82 (1H, s, metallocene),
4.71 (1H, s, metallocene), 4.48 (1H, s, metallocene), 4.29
(5H, s, metallocene); EIMS (M+) m/z: 490. Anal. Calc.
for C20H14Cl3FeN3O2: C 48.97, H 2.88, N 8.57. Found:
C 49.07, H 2.78, N 8.58%.
4.3. Biological evaluation
4.3.1. Antifungal activity
Antifungal activity of the title compounds 10a–j were
assayed against powdery mildew and brown rust on intra-
vital wheat plants at the Biological Assay Centre, Nankai
University according to procedures described previously
[19]. The five selected fungi included I. clavispora, B. lactu-
cae, C. fulvum, E. graminis, and A. mali.
4.2.6. 2-(4-Nitrophenoxy)-1-ferrocenyl-2-(1H-1,2,4-triazol-
1-yl)ethanone (10f)
Red solid; yield 75.0%; m.p. 159–160 ꢁC; 1H NMR
d(300 MHz, d6-DMSO): 9.04 (1H, s, C30, triazole), 8.18
(1H, s, C50, triazole), 7.31–7.43 (4H, m, aryl), 7.76 (1H,
s, CHTr), 4.97 (2H, s, metallocene), 4.86 (1H, s, metallo-
cene), 4.77 (1H, s, metallocene), 4.31 (5H, s, metallocene);
EIMS (M+) m/z: 432. Anal. Calc. for C20H16FeN4O4: C
55.58, H 3.73, N 12.96. Found: C 55.50, H 3.70, N 13.05%.
4.3.2. Plant growth regulatory activity
Plant growth regulatory activity of compounds 10a–j
was screened using cucumber cotyledon rhizogenesis
method at the same department as above. The detailed pro-
cedure was described as following:
4.2.7. 2-(3-Methyl-6-chlorophenoxy)-1-ferrocenyl-2-(1H-
1,2,4-triazol-1-yl)ethanone (10g)
After dipped in distilled water for 1 h at 23 ꢁC, the
cucumber seed (JINKE, No. 4, commercial availably)
was then sowed into soil with 0.7% agar at a covered por-
celain enamel plate and incubated at 26 ꢁC in a darkroom
for 3 days. The same size cotyledons were carefully selected
to subsequent biological assay. The tested compound
(3 mg) was resolved in N,N-dimethylformamide (3 mL)
and this solution was then diluted to 10% concentration
with distilled water. A sample solution (0.3 mL) was
sprayed over a 6-cm diameter filter paper and solvent
was volatilized to dryness on air. The filter paper thus pre-
pared was placed into a 6-cm diameter incubation vessel
and soaked with 10 mL distilled water. Finally, ten pieces
of the same size cotyledons were added into incubation ves-
sel. These cotyledons were incubated at 26 ꢁC in a dark-
room for 5 days. At that moment, the rhizogenesis
numbers of every ten pieces of hypocotyls were measured.
Each sample was repeated twice. In contrast, the distilled
water was used as control experiment.
1
Pale red solid; yield 50.3%; m.p. 140–142 ꢁC; H NMR
d(300 MHz, d6-DMSO): 8.95 (1H, s, C30, triazole), 8.14
(1H, s, C50, triazole), 7.46–7.08 (3H, m, aryl), 7.26 (1H,
s, CHTr), 4.96 (2H, s, metallocene), 4.85 (1H, s, metallo-
cene), 4.77 (1H, s, metallocene), 4.30 (5H, s, metallocene),
2.31 (3H, s, CH3); EIMS (M+) m/z: 436. Anal. Calc. for
C21H18ClFeN3O2: C 57.89, H 4.16, N 9.64. Found: C
58.06, H 4.29, N 9.43%.
4.2.8. 2-(2,4-Dibromophenoxy)-1-ferrocenyl-2-(1H-1,2,4-
triazol-1-yl)ethanone (10h)
Red solid; yield 83.2%; m.p. 140–142 ꢁC; 1H NMR
d(300 MHz, d6-DMSO): 8.92 (1H, s, C30, triazole), 8.18
(1H, s, C50, triazole), 7.92–7.24 (3H, m, aryl), 7.51 (1H,
s, CHTr), 4.99 (1H, s, metallocene), 4.92 (1H, s, metallo-
cene), 4.86 (1H, s, metallocene), 4.75 (1H, s, metallocene),
4.29 (5H, s, metallocene); EIMS (M+) m/z: 545. Anal. Calc.

Z. Jin et al. / Journal of Organometallic Chemistry 691 (2006) 2340–2345
2345
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Relative ratio % = (NS ꢀ NC)/NC · 100 %, where NS and
NC are the numbers of cucumber cotyledon rhizogenesis of
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5. Supplementary material
Crystallographic data for compound 10f has been
deposited with the Cambridge Crystallographic Data Cen-
ter, CCDC No. 279 272. Copies of this information may be
obtained free of charge from: The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223
336033; e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
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Acknowledgments
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1021;
The present work was financially supported by the Na-
tional Natural Science Foundation of China (NNSFC)
(Nos. 29872022, 20172030) and the Research Fund for
the Doctoral Program of Higher Education (RFDP) (No.
9805520).
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