Syntheses, crystal structures, and electrochemical properties of multi-ferrocenyl resorcinarenes

Article abstract of DOI:10.1016/j.tet.2006.12.073

Tetraaryl and tetraferrocenyl resorcinarenes 1a-1c have been synthesized by the HCl-catalyzed condensation of resorcinol with aromatic aldehydes or ferrocenecarbaldehyde, which were fully alkylated with ethyl α-chloroacetate to give the activated ethyl re

Full text of DOI:10.1016/j.tet.2006.12.073

Tetrahedron 63 (2007) 2275–2282
Syntheses, crystal structures, and electrochemical properties
of multi-ferrocenyl resorcinarenes
b
Jun Han,a Ya Hua Cai,a Li Liu,a Chao Guo Yana, and Qi Li
*
aCollege of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China
bDepartment of Chemistry, Beijing Normal University, Beijing 100875, China
Received 29 September 2006; revised 20 December 2006; accepted 21 December 2006
Available online 27 December 2006
Abstract—Tetraaryl and tetraferrocenyl resorcinarenes 1a–1c have been synthesized by the HCl-catalyzed condensation of resorcinol with
aromatic aldehydes or ferrocenecarbaldehyde, which were fully alkylated with ethyl a-chloroacetate to give the activated ethyl resorcinar-
ylacetates 2a–2c. Reaction of 2a–2c with hydrated hydrazine yielded the resorcinarene acylhydrazine derivatives 3a–3c, from which the
multi-ferrocenyl functional groups were selectively and efficiently introduced on the upper rim, or on the lower rim, or both on the upper
and lower rims of resorcinarenes 4a–4c and calixarenes 4d–4f based upon the condensation reactions of acylhydrazones with ferrocenecar-
boxaldehyde.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
other metallocene23–26 units to the lower and upper rims of
calixarenes and resorcinarenes, many of which include an
amide hydrogen-bonding group.27–28 Anions may be recog-
nized in a range of environmental conditions, with some
receptors even being active in aqueous solution.29–31 The
tetraferrocenyl resorcinarenes were also obtained from the
condensation of resorcinol with ferrocenecarboxaldehyde.17
In continuation of our studies on molecular design of calix-
arene acceptors, we are interested in constructing multi-
ferrocene functional groups on p-tert-butylcalix[n]arenes
and resorcinarenes. In this paper, we report a selective and
efficient procedure to introduce ferrocenes on the upper
rim, or on the lower rim, or both on the upper and lower
rims of resorcinarenes and calixarenes based upon the con-
densation reactions of acylhydrazones with ferrocenecar-
boxaldehyde.
Calixarenes and resorcinarenes have become popular tem-
plates for a number of chemical investigations because it
can be produced selectively in large quantities from cheap
commercial starting materials and can easily be chemically
modified, leading to versatile tail-made receptors.1–3 In
order to design new types of valuable receptor molecules
and supramolecular structures, various methods have been
developed for complete and selective modification on the
upper and lower rims of calixarenes and resorcinarenes.4–5
Recently, molecular design of calixarenes and resorcinar-
enes for anion recognition and sensing has become an
increasingly important research topics in supramolecular
chemistry because selective binding of anions is more de-
manding than that of cations in view of the high free energies
of solvation of anions and that the frequently occurring pH
dependency of anion complexation.6–8 The incorporation
of redox-active centers, such as ferrocene into ligands of
the calixarene type aimed at the development of molecular
sensory devices, which allow electrochemical recognition
of trapped guests, has attracted much more attention in the
past years. Ferrocene does not directly interact with anions
until it is oxidized to ferrocenium, when electrostatic interac-
tions are switched on. Beer and co-workers firstly prepared
metallocene amide receptors for binding and sensing
anions.9–10 From then Beer and others reported a lot of works
with different strategies for introducing ferrocene11–22 and
2. Results and discussion
2.1. Synthesis and characterization
Tetraaryl resorcinarenes, which can be easily prepared from
the condensation of resorcinol with aromatic aldehydes,
have received less attention compared to tetraalkyl resorci-
narenes32–34 because tetraaryl resorcinarenes have less solu-
bility in common solvents and are much difficult for
chemical modifications. But rigid aryl groups might create
a more stable conformation for resorcinarenes and result
in much high selective recognition. Thus resorcinarenes
1a–1c with phenyl, p-hydroxyphenyl, and ferrocenyl groups
were prepared in high yields from the condensation of
Keywords: Resorcinarene; Calixarene; Ferrocene; Conformation; Crystal
structure.
* Corresponding author. E-mail: cgyan@yzu.edu.cn
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.12.073

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J. Han et al. / Tetrahedron 63 (2007) 2275–2282
OCH2COOC2H5
OH
C2H5OOCH2CO
ClCH2COOC2H5
HO
4
KI,K2CO3,acetone
4
R
R
1a: R=C6H5
2a: R=C6H5
1b: R=C6H4OH
1c: R=Fc
2b: R=C6H4OCH2COOC2H5
2c: R=Fc
H2NNH2
OCH2CONHNH2
H2NHNOCH2CO
OCH2CONHN=CH
Fc
HC=NHNOCH2CO
Fc
FcCHO
acetic acid
4
4
R
R
3a: R=C6H5
4a: R=C6H5
4b: R=C6H4OCH2CONHN=CHFc
4c: R=Fc
3b: R=C6H4OCH2CONHNH2
3c: R=Fc
Scheme 1. Synthesis of multi-ferrocenyl resorcinarenes.
with ethyl a-chloroacetate in K2CO3/KI/acetone system to
give active ester derivatives 2a–2c in 50–70% yield, which
make it possible to modify resorcinarene on the upper rim.
It must be noticed that there are 8, 12, or 8 active ester groups
in 2a–2c, respectively, for the p-hydroxyphenyl groups in 1b
would be also alkylated in this procedure. The structures of
2a–2c were characterized by spectroscopic data and fully
confirmed by the X-ray single crystal analysis.
The molecular structures are shown in Figures 1–3. The
crystal structures give stronger evidence that all hydroxyl
groups have been alkylated by ethyl a-chloroacetate to
give fully alkylated ethyl calixarylacetate. It can be seen
that in 2a–2c the four resorcinol units in the ring were di-
vided into two groups with two resorcinol rings almost per-
pendicular to the other two resorcinol rings, which show the
resorcinarene in boat conformation, with much distorted in
a propeller-like manner in 2c. The stretching directions of
two perpendicular resorcinol rings are opposite. One is up-
per standing and the other is upside down. It is interesting
Figure 1. The crystal structure of 2a.
resorcinol with benzaldehyde, p-hydroxybenzaldehyde, and
ferrocenecarboxaldehyde according to the published method
(Scheme 1).32–34 Although having very poor solubilities in
common solvents, 1a–1c can still be fully O-alkylated
Figure 2. The crystal structure of 2b.

J. Han et al. / Tetrahedron 63 (2007) 2275–2282
2277
transformed into acylhydrazine groups. The molecular
structures of acylhydrazine derivatives 3a–3f were fully
confirmed by the X-ray single crystal analysis of one repre-
sentative compound 3d (Fig. 4). It exists in cone confor-
mation with the four acylhydrazine groups orienting in the
same direction.
Even if 3a–3f had very poor solubility in common solvent,
the suspension of acylhydrazine derivatives 3a–3f in acetic
acid at room temperature reacted smoothly with ferrocene-
carbaldehyde to yield brown precipitates as the ferrocenyl
hydrazone products 4a–4f in satisfied yields (62–89%). In
the IR spectra of ferrocenyl hydrazones 4a–4f, the absorp-
tion band of C]O appears at about 1680 cmꢀ1 and the
absorption of N]CH was observed with a strong peak at
about 1610 cmꢀ1. Thus multi-ferrocenyl groups have been
successfully introduced into the calixarene plateform.
Figure 3. The crystal structure of 2c.
to find that in 2a and 2c the four phenyl groups and ferro-
cenyl groups are located in the lower rim direction. Com-
pounds 2a and 2c show rccc (all cis) conformation.
Compound 2b exists in rctt (cis–trans–trans) conformation,
in which two neighboring p-hydroxyphenyl groups are lo-
cated in upper rim direction with other two p-hydroxyphenyl
groups lying at the opposite direction. Thus the 12 ethoxy-
carbonylmethoxy groups in the calixarene are peripherally
stretched from resorcinarene core, which give a good advan-
tage for the preparation of dendrite molecules.
Refluxing 2a–2c or ethyl p-tert-butylcalix[n]aryl acetates
2d–2f (n¼4, 6, 8)35 with excess of hydrated hydrazine in eth-
anol gave the corresponding calixaryl acylhydrazine deriva-
tives 3a–3f as white solid in excellent yields (85–92%,
Scheme 2). It should be pointed out that beside 3d, other
acylhydrazine derivatives have very poor solubility in most
organic solvents, which makes great difficulty to get satisfied
characterization data for them. Compound 3d has good sol-
ubility in common organic solvent because it has only four
hydrazine groups, while others have 6–12 hydrazine groups.
In the IR spectra of 3a–3f, the C]O group of acylhydrazine
shows stronger absorption band at 1680 cmꢀ1, while C]O
group of ester in 2a–2f appears at 1750 cmꢀ1, which
indicates that all ethyl ester groups in 2a–2f have been
Figure 4. The crystal structure of 3d.
ClCH2COOC2H5
KI,K2CO3,acetone
n
n
OH
OCH2COOC2H5
2d: n=4, 2e: n=6, 2f: n=8
1d: n=4, 1e: n=6, 1f: n=8
H2NNH2
FcCHO
acetic acid
n
n
OCH2CONHN=CHFc
4d: n=4, 4e: n=6, 4f: n=8
OCH2CONHNH2
3d: n=4, 3e: n=6, 3f: n=8
Scheme 2. Synthesis of multi-ferrocenyl calixarenes.

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J. Han et al. / Tetrahedron 63 (2007) 2275–2282
at the upper rim and four ferrocenyl groups at side position
of resorcinarene (Scheme 3).
Fe
OCH2CONHN=CH
Fe
HC=NHNOCH2CO
HC=NHNOCH2CO
4a
4
Refluxing resorcinarene acylhydrazines 3a and 3c with ex-
cess of acetoacetone in THF caused the formation of pyra-
zole derivatives 5a and 5c in moderate yields (Scheme 4).
Compounds 5a and 5c were characterized and gave further
evidence to the structure of the resorcinarene acylhydrazine.
OCH2CONHN=CH
Fe
Fe
4c
4
2.2. Electrochemical properties
Fe
The electrochemical properties of the resorcinarene com-
pounds 2c and 4a–4f (Fig. 5) with the redox-active ferro-
cenyl groups were studied by cyclic voltammetry, which is
a sensitive electrochemical method and permits the collec-
tion of excellent data at low concentration of electroactive
substance.36,37 The values obtained for the peak potentials
of the anodic and cathodic waves (Epa and Epc, respectively)
for the oxidation processes are given in Table 1. The
Scheme 3. Concise representation of molecules 4a and 4c.
According to the crystal structure of the ester precursors 2a–
2c, the ferrocenyl groups must occupy the different positions
of the calixarene. In 4a all eight ferrocenyl groups are at the
upper rim. In 4c there are eight ferrocenyl hydrazone groups
O
O
N
N
OCH2CONHNH2
H2NHNOCH2CO
OCH2C
N
N
CH2CO
O
O
4
4
R
R
3a: R=C6H5
3c: R=Fc
5a: R=C6H5
5b: R=Fc
Scheme 4. Synthesis of resorcinarene pyrazole derivatives 5a and 5b.
(b)
4.0x10-6
3.0x10-6
2.0x10-6
(a)
1.8x10-4
1.6x10-4
1.4x10-4
1.2x10-4
1.0x10-4
8.0x10-5
6.0x10-5
4.0x10-5
4c
2c
4a
4b
1.0x10-6
0.0
2.0x10-5
0.0
-2.0x10-5
-4.0x10-5
-6.0x10-5
-8.0x10-5
-1.0x10-4
-1.2x10-4
-1.0x10-6
-2.0x10-6
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
Potential vs. SCE (V)
Potential vs. SCE (V)
(c)
4.0x10-5
4d
4e
4f
2.0x10-5
0.0
-2.0x10-5
-4.0x10-5
-6.0x10-5
-8.0x10-5
1.0
0.8
0.6
0.4
0.2
0.0
Potential vs. SCE (V)
Figure 5. Cyclic voltammetric curves (5ꢁ10ꢀ4 M CH2Cl2 solution, 0.1 M Bu4NClO4 (TBAP), 298 K; scan rate 50 mV sꢀ1) for the ferrocene units in (a) 2c,
(b) 4a–4c, and (c) 4d–4f.

J. Han et al. / Tetrahedron 63 (2007) 2275–2282
Table 1. Electrochemical data of 2c and 4a–4f at scan rates 50 mV sꢀ1
2279
number, which also indicates that this electrochemical
process is irreversible. The group CH]N in 4a–4f may be
contributing to electrochemical process, their strong elec-
tron-withdrawing effect causes an increase in anodic poten-
tial of 4a–4f compared with the data of ferrocene itself.
Entry
(Fcꢀe/Fc+)
Epa (V)
Epc (V)
DEp (V)
E1/2 (V)
FcH
2c
4a
4b
4c
4d
4e
4f
0.548
0.550
0.655
0.628
0.585
0.734
0.700
0.779
0.441
0.292
0.354
0.382
0.352/0.324
0.528
0.476
0.107
0.258
0.301
0.246
—
0.206
0.224
0.224
0.494
0.421
0.505
0.505
—
0.631
0.588
0.667
3. Experimental
3.1. General remarks
0.555
3.1.1. Materials. All reagents and solvents were commer-
cially available with analytical grade and used as received.
Further purification and drying by standard method were
employed and distilled prior to use when necessary. All
evaporations of organic solvents were carried out with a ro-
tary evaporator in conjunction with a water aspirator. The
plates used for thin-layer chromatography (TLC) were silica
gel GF254 (0.25 mm thickness) precoated on glass plates,
and they were visualized under both long (365 nm) and short
(254 nm) UV light. Flash column chromatography was
performed on silica gel H (6w8 cm thickness). Tetra-n-butyl-
ammonium perchlorate (TBAP) was prepared by treatment
of tetra-n-butylammonium bromide, and recrystallized three
times from ethanol and dried under vacuum for 24 h.
Ferrocenecarboxaldehyde,40 resorcinarenes 1a–1c,32–34
p-tert-butylcalix[n]arenes41 1d–1f (n¼4, 6, 8), and ethyl
calixarylacetate35 2d–2f were prepared according to the
published methods.
All potentials are referred to the saturated calomel electrode (SCE) in
CH2Cl2 solution.
electrochemical results of the investigated compounds were
compared to that of ferrocene.
The cyclic voltammetric behavior of compounds 2c and 4a–
4f showed one redox wave in the potential range of 0–1.0 V
suggesting that ferrocene units of each compound were in
the same ferrocenyl environment. The separation of the
anodic and the cathodic peak potentials, DEp, was 258,
301, 246, 206, 224, and 224 mV at 50 mV sꢀ1 for com-
pounds 2c, 4a, 4b, and 4d–4f, respectively. These values
were larger or smaller than that expected for a reversible
4-, 6-, 8-, and 12-electron transfer reaction, which is given
by jEp ꢀ Ep=2j ¼ 56:5=n mV, where n is the number of elec-
tron transferred in the process,38 indicating that the electron
transfer process was irreversible under this condition. Other-
wise, the larger the scan rate, the broader the observed DEp
would be. It is probably due to the onset of kinetic compli-
cations. The peak current of the redox couples described
above is not proportional to the square root of the scan rate
(50–250 mV sꢀ1), indicating that the electrochemical pro-
cesses are adsorption-controlled.39 Compound 4c shows
much complicated redox waves because it has two kinds
of ferrocenyl subunits, which are eight ferrocenyl acylhydra-
zone groups and four outer ferrocenyl groups. Two reduction
peaks at 0.352 and 0.324 V are observed with only one
oxidation peak (Fig. 5b), which is possibly due to peak-
superposition. DPV (differential pulse voltammetry) is ap-
plied to 4c in order to distinguish two kinds of ferrocenyl
groups (Fig. 6). The result is disappointing. The number of
electron transferred in the process is less than the academic
3.1.2. Apparatus. Melting points were taken on a hot-plate
microscope apparatus and were uncorrected. 1H NMR spec-
tra were recorded with a Bruker AV-600 spectrophotometer
(600 MHz for 1H NMR). They were carried out at room tem-
perature in deuterated trichloromethane solution unless
otherwise stated. Chemical shifts are reported as parts per
million (ppm) in d units on the scale downfield from tetra-
methylsilane (TMS). 1H NMR data are reported in this
order: chemical shift, multiplicity, numbers of proton, group
of proton. IR spectra were obtained on a Bruker Tensor27
spectrometer (KBr disc). Elemental analysis was obtained
on Perkin–Elmer 2400 SERIESII Instrument. X-ray data
were collected on a Bruker Smart APEX-2 diffractometer.
The cyclic voltammograms were recorded with a Shanghai
ZhenHua CHI 660A recorder.
4c
0.0
3.2. General procedure for the syntheses of 2a–2c
-5.0x10-7
-1.0x10-6
-1.5x10-6
-2.0x10-6
-2.5x10-6
-3.0x10-6
A suspension of 1a–1c (3.0 mmol) and anhydrous potassium
carbonate (8.28 g, 60 mmol), and potassium iodide (0.5 g,
3.0 mmol) in dry acetone (120 mL) was heated to reflux un-
der nitrogen for at least 0.5 h. Then ethyl a-chloroacetate
(5.3 mL, 50 mmol) was added. The reaction mixture was re-
fluxed for 7 days. After removal of acetone, the residue was
dissolved in water, acidified with hydrochloric acid, and then
extracted with CHCl3. The yellow organic layers were sep-
arated and dried with MgSO4. Red oil was yielded after
evaporation of the solvent, which was titrated with alcohol
to give yellow products, and recrystallized from ethanol to
give pure solid of 2a–2c.
1.0
0.8
0.6
0.4
0.2
0.0
Potential vs. SCE (V)
Figure 6. Differential pulse voltammetry of 4c; pulse amplitude: 50 mV;
pulse width: 50 ms; amplitude: 50 mV; scan rate: 0.004 V sꢀ1; other condi-
tions as in Figure 5.
3.2.1. Compound 2a. White solid, 69.5%, mp 143–144 ꢂC.
1
IR (KBr disc, cmꢀ1) n: 1760 (C]O). H NMR (600 MHz,

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J. Han et al. / Tetrahedron 63 (2007) 2275–2282
CDCl3) d: 6.2–6.9 (m, 28H, ArH), 5.9 (s, 4H, CH), 4.25–4.30
(m, 16H, OCH2), 4.1–4.2 (m, 16H, CH2), 1.2–1.3 (m, 24H,
CH3). Anal. Calcd for C84H88O24: C, 68.10; H, 5.99. Found:
C, 68.25; H, 5.71.
(s), 2893 (m), 2858 (m), 1668 (vs), 1597 (m), 1470 (vs),
1351 (m), 1182 (s), 1104 (m). Anal. Calcd for
C78H108N12O12: C, 66.64; H, 7.74; N, 11.96. Found: C,
66.27; H, 7.36; N, 12.37.
3.2.2. Compound 2b. White solid, 56.5%, mp 151–153 ꢂC.
3.3.6. Compound 3f. White solid, 95.2%; mp 290 ꢂC
(decomp.). IR (KBr, cmꢀ1) n: 3316 (m), 3041 (m), 2957
(s), 2893 (m), 2858 (m), 1668 (vs), 1604 (m), 1470 (vs),
1280 (m), 1182 (s), 1104 (m). Anal. Calcd for
C104H144N16O16: C, 66.64; H, 7.74; N, 11.96. Found: C,
66.81; H, 8.23; N, 11.73.
1
IR (KBr disc, cmꢀ1) n: 1760 (C]O). H NMR (600 MHz,
CDCl3) d: 6.2–6.6 (m, 24H, ArH), 5.9 (s, 4H, CH), 4.3–4.5
(m, 24H, OCH2), 4.1–4.6 (m, 24H, CH2), 1.2–1.3 (m, 36H,
CH3). Anal. Calcd for 2b$2CHCl3 (C102H114O36Cl6): C,
57.55; H, 5.40. Found: C, 57.27; H, 5.27.
3.2.3. Compound 2c. Yellow solid, 69.0%, mp 135 ꢂC. IR
3.4. General procedure for the syntheses of 4a–4f
1
(KBr disc, cmꢀ1) n: 1758 (C]O). H NMR (600 MHz,
CDCl3) d: 6.24 (s, 4H, ArH), 6.13 (s, 4H, ArH), 5.53 (s,
4H, ArCHAr), 4.23 (s, 16H, OCH2), 4.05 (s, 8H, C5H4),
4.02 (s, 20H, Cp), 3.84 (s, 8H, C5H4), 1.29–1.30 (m, 16H,
CH2), 1.28–1.27 (m, 24H, CH3). Anal. Calcd for
2c$H2O$C2H5OH (C102H112Fe4O26): C, 61.96; H, 5.71;
Found: C, 61.80; H, 5.69.
To a solution of calixaryl acylhydrazines 3a–3f (0.1 mmol)
in 5 mL of acetic acid was added dropwise ferrocenecarbal-
dehyde (1.1 mol for each hydrazine group) in 10 mL of
ethanol in 10 min. Then the mixture was stirred under nitro-
gen at room temperature overnight. The precipitates were
collected by filtration, washed with ethanol (until the filtrate
was colorless), and dried in vacuum to give orange solid
products 4a–4f.
3.3. General procedure for the syntheses of 3a–3f
A mixture of ethyl resorcinarylacetates 2a–2c or ethyl p-
tert-butylcalixarylacetates 2d–2f (0.50 mmol) and hydrated
hydrazine (10 mL, 80%) in 15 mL of ethanol was refluxed
for 24 h. After cooling to room temperature the resulting
precipitate was collected by filtration and washed with abso-
lute alcohol to give the white solid of 3a–3b, 3d–3f and
yellow solid 3c.
3.4.1. Compound 4a. Yellow-orange solid, yield: 89.7%;
mp 250 ꢂC. IR (KBr disc, cmꢀ1) n: 3403 (m), 1686 (vs),
1609 (s), 1496 (s), 1439 (w), 1279 (m), 1189 (m), 1105
1
(m), 821 (m), 701 (m). H NMR (600 MHz, DMSO-d6) d:
8.10 (s, 8H, NH), 7.01 (s, 8H, CH]N), 5.97–6.34 (m,
28H, ArH), 5.75 (s, 4H, ArCHAr, CH), 4.55–4.63 (m,
16H, CH2), 4.41–4.22 (m, 32H, C5H4), 4.15 (s, 40H, Cp).
Anal. Calcd for C156H136Fe8N16O16: C, 63.78; H, 4.67; N,
7.63. Found: C, 64.25; H, 4.79; N, 7.21.
3.3.1. Compound 3a. White solid, 92.0%; mp >250 ꢂC. IR
(KBr disc, cmꢀ1) n: 3397 (s), 1683 (vs), 1612 (s), 1503 (vs),
1438 (m), 1407 (m), 1299 (s), 1199 (s), 1161 (m), 1106 (s),
1061 (s), 930 (m), 709 (m). Anal. Calcd for C68H72N16O16:
C, 56.64; H, 5.30; N, 16.37. Found: C, 57.10; H 5.52; N,
15.89.
3.4.2. Compound 4b. Yellow-orange solid, yield: 62.9%;
mp >250 ꢂC. IR (KBr disc, cmꢀ1) n: 3401 (m), 1681 (vs),
1609 (s), 1507 (s), 1440 (w), 1253 (m), 1189 (m), 1105
1
(m), 824 (m). H NMR (600 MHz, DMSO-d6) d: 8.10 (s,
12H, NH), 6.97 (s, 12H, CH]N), 5.96–6.30 (m, 24H,
ArH), 5.75 (s, 4H, ArCHAr, CH), 4.79–4.82 (m, 24H,
CH2), 4.30–4.40 (m, 48H, C5H4), 4.17 (s, 60H, Cp). Anal.
Calcd for C208H184Fe12N24O24: C, 61.32; H, 4.55; N, 8.25.
Found: C, 61.27; H, 5.07; N, 8.57.
3.3.2. Compound 3b. White solid, 85.0%; mp >250 ꢂC. IR
(KBr disc, cmꢀ1) n: 3401 (s), 1680 (s), 1611 (s), 1508 (vs),
1438 (m), 1405 (m), 1296 (s), 1160 (m), 1103 (m), 1106
(s), 1030 (m), 927 (w), 827 (w). Anal. Calcd for
C76H88N24O24: C, 53.02; H, 5.15; N, 19.53. Found: C,
52.75; H 5.38; N, 19.27.
3.4.3. Compound 4c. Red-orange solid, yield: 79.0%; mp
209 ꢂC (decomp.). IR (KBr disc, cmꢀ1) n: 3441 (s), 2918
(vs), 2549 (s), 1884 (vs), 1618 (m), 1487 (m), 1282 (m),
1105 (s), 1022 (w), 818 (w), 785 (m). 1H NMR (600 MHz,
DMSO-d6) d: 7.97 (s, 8H, NH), 6.73 (s, 8H, CH]N),
6.54–6.60 (s, 8H, ArH), 5.83 (s, 4H, ArCHAr, CH), 4.54–
4.62 (m, 16H, CH2), 4.17–4.37 (m, 108H, C5H4). Anal.
Calcd for C172H152Fe12N16O16: C, 61.31; H, 4.54; N, 6.65.
Found: C, 60.78; H, 4.83; N, 6.22.
3.3.3. Compound 3c. Yellow solid, 75.8%; mp 198 ꢂC. IR
(KBr disc, cmꢀ1) n: 2405 (s), 1672 (vs), 1500 (vs), 1197
(s), 1060 (ms), 1145 (ms), 873 (w). Anal. Calcd for
C84H88Fe4N16O16: C, 56.02; H, 4.92; N, 12.44. Found: C,
56.23; H, 5.18; N, 12.65.
3.3.4. Compound 3d. White solid, 86.8%; mp 275 ꢂC
(decomp.). IR (KBr disc, cmꢀ1) n: 3316 (m), 3041
(m), 2957 (s), 2893 (m), 2858 (m), 1661 (vs), 1597 (m),
1470 (vs), 1351 (m), 1189 (s), 1111 (m). 1H NMR
(600 MHz, CDCl3) d: 9.25 (s, 4H, NH), 6.86 (s, 8H, ArH),
4.46 (s, 8H, OCH2), 4.30, 3.27 (d, d, J¼6.4 Hz, 8H, CH2),
1.08 (s, 36H, C(CH3)3). Anal. Calcd for C52H72N8O8:
C, 66.64; H, 7.74; N, 11.96. Found: C, 66.75; H, 7.09;
N, 12.23.
3.4.4. Compound 4d (n¼4). Yellow-orange solid, yield:
67.7%; mp >250 ꢂC. IR (KBr disc, cmꢀ1) n: 3441 (m),
2960 (s), 1689 (vs), 1628 (s), 1479 (s), 1244 (m), 1104
(m). 1H NMR (600 MHz, CDCl3) d: 8.48 (s, 4H, NH),
7.15 (s, 4H, CH]N), 6.43–6.57 (m, 8H, ArH), 4.78 (s,
8H, C5H4), 4.46 (s, 8H, C5H4), 4.23 (s, 20H, Cp), 4.15
(s, 8H, OCH2), 3.45–3.49 (m, 8H, ArCH2Ar, CH), 1.24 (s,
12H, C(CH3)3), 0.84 (s, 24H, C(CH3)3). Anal. Calcd for
C96H104Fe4N8O8: C, 66.99; H, 6.09; N, 6.51. Found: C,
66.63; H, 6.28; N, 6.39.
3.3.5. Compound 3e. White solid, 90.7%; mp 300 ꢂC
(decomp.). IR (KBr, cmꢀ1) n: 3316 (m), 3041 (m), 2950

J. Han et al. / Tetrahedron 63 (2007) 2275–2282
2281
3.4.5. Compound 4e (n¼6). Yellow-orange solid, yield:
69.0%; mp >250 ꢂC. IR (KBr disc, cmꢀ1) n: 3437 (m),
2960 (s), 1680 (vs), 1611 (s), 1470 (m), 1188 (m), 1107
(m). 1H NMR (600 MHz, CDCl3) d: 8.38 (s, 6H, NH),
7.17 (s, 6H, CH]N), 6.69–7.07 (m, 12H, ArH), 4.40–4.89
(m, 24H, C4H5), 4.21–4.28 (s, 30H, Cp), 3.98 (s, 12H,
OCH2), 3.79–3.86 (m, 12H, ArCH2Ar, CH), 1.21–1.29 (m,
54H, C(CH3)3). Anal. Calcd for C144H156Fe6N12O12: C,
66.99; H, 6.09; N, 6.51. Found: C, 66.67; H, 6.31; N, 6.31.
residue was dissolved in 3 mL of CHCl3 and filtered, and
powder was collected when 3 mL of ethanol was added
into the above yellow CHCl3 solution. Recrystallization
from ethanol gave pure white solid for 5a or yellow solid
for 5b.
3.5.1. Compound 5a (R¼H). White solid, yield: 40.0%; mp
143–145 ꢂC. IR (KBr disc, cmꢀ1) n: 3477 (w), 3414 (w),
1747 (vs), 1614 (w), 1585 (m), 1495 (m), 1438 (m), 1401
(s), 1328 (m), 1298 (m), 1161 (m), 1255 (m), 960 (s), 807
1
3.4.6. Compound 4f (n¼8). Yellow-orange solid, yield:
74.4%; mp >250 ꢂC. IR (KBr disc, cmꢀ1) n: 3412 (m),
2957 (s), 1689 (vs), 1621 (s), 1477 (s), 1181 (m), 1102
(m). 1H NMR (600 MHz, CDCl3) d: 8.35 (s, 8H, NH),
7.15 (s, 8H, CH]N), 6.69–7.07 (m, 16H, ArH), 4.44–4.73
(m, 32H, C4H5), 4.22–4.28 (s, 40H, Cp), 3.98 (s, 16H,
OCH2), 3.79–3.83 (m, 16H, ArCH2Ar, CH), 1.22–1.31 (m,
72H, C(CH3)3). Anal. Calcd for C192H208Fe8N16O16: C,
66.99; H, 6.09; N, 6.51. Found: C, 66.59; H, 6.55; N, 6.26.
(m). H NMR (CDCl3) d: 6.98 (s, 8H, ArH), 6.88 (s, 4H,
ArH), 6.79 (s, 8H, ArH), 6.40–6.54 (m, 8H, ArH), 6.16 (s,
4H, CH), 5.84–5.88 (m, 8H, CH), 5.11–5.36 (m, 16H,
OCH2), 2.43 (s, 24H, CH3), 2.09–2.18 (m, 24H, CH3). 13C
NMR (CDCl3) d: 13.5, 13.8, 69.5, 110.6, 125.2, 126.7,
128.3, 129.0, 129.1, 129.2, 132.4, 142.3, 144.0, 144.1,
152.1, 152.3, 154.7, 154.9, 168.4. Anal. Calcd for
C108H104N16O16: C, 68.92; H, 5.57; N, 11.90. Found: C,
68.55; H, 5.83; N, 12.28.
3.5. General procedure for the syntheses of 5a and 5b
3.5.2. Compound 5b (R¼Fc). Yellow solid, yield: 35.0%;
mp 188–189 ꢂC (decomp.). IR (KBr disc, cmꢀ1) n: 3441
(w), 3133 (w), 2956 (m), 1746 (s), 1629 (s), 1496 (m),
1400 (vs), 1328 (s), 1255 (m), 1151 (m), 1106 (m), 962
(s), 803 (m). H NMR (CDCl3) d: 6.82 (s, 8H, ArH), 6.38
(s, 4H, CH), 5.73–5.83 (m, 8H, CH), 5.24 (s, 16H, OCH2),
4.01–4.23 (m, 36H, Cp), 2.35 (s, 24H, CH3), 2.05 (s, 24H,
Calixaryl acylhydrazine 3a or 3c (0.1 mmol), an excess of
acetoacetone (3.0 mL), and a little p-toluenesulfonic acid
were added as catalysts in 30 mL of anhydrous THF. The
mixture was heated under reflux for 72 h under nitrogen.
The solvent was removed under reduced pressure, and the
1
Table 2. Crystal data and structure refinement details of 2a–2c and 4d
2a
2b
2c
4d
Empirical formula
Formula weight
Temperature (K)
C84H88O24
1481.54
293(2)
0.71073
Triclinic, P-1
C100H112O36$2CHCl3
2086.87
173(2)
0.71070
Triclinic, P-1
C102H112Fe4O26
1977.32
293(2)
0.71073
Monoclinic, P21/n
C56H81N8O10
1026.29
293(2)
0.71073
Monoclinic, P2(1)/c
˚
Wavelength (A)
Crystal system,
space group
Unit cell dimensions
˚
˚
˚
˚
a¼12.160(0) A,
a¼11.0389(7) A,
a¼13.9751(3) A,
a¼23.742(5) A,
a¼78.470ꢂ,
a¼64.406(13)ꢂ,
a¼90 , b¼27.7708(6) A,
a¼90 , b¼13.266(3) A,
ꢂ
ꢂ
˚
˚
b¼17.530(0) A,
b¼17.1440(6) A,
b¼100.4270(10)ꢂ,
b¼97.639ꢂ,
˚
˚
b¼77.630ꢂ,
b¼73.919(16)ꢂ,
c¼25.4590(5) A,
c¼20.975(4) A,
˚
˚
c¼19.260(0) A,
c¼17.4008(6) A,
g¼90ꢂ
g¼90ꢂ
˚
˚
g¼79.790ꢂ
3890.4
2
g¼71.743(16)ꢂ
2781.6(2)
1
3
Volume (A )
˚
9717.5(4)
4
1.352
6080(2)
4
1.121
Z
Calculated density
1.265
1.246
(g cmꢀ3
)
Absorption coefficient
(mmꢀ1
F(000)
Crystal size (mm)
q Range for data
collection
0.093
0.229
0.661
0.077
)
1568
0.2ꢁ0.2ꢁ0.3
1039
0.1ꢁ0.27ꢁ0.3
4144
0.2ꢁ0.2ꢁ0.3
2212
0.20ꢁ0.20ꢁ0.20
1.10–24.99
3.02–25.35
1.68–25.00
1.80–25.98
hkl Ranges
0 to 14, ꢀ20 to 20,
ꢀ20 to 22
ꢀ12 to 13, ꢀ20 to 20,
ꢀ20 to 18
ꢀ14 to 16, ꢀ33 to 27,
ꢀ30 to 30
ꢀ26 to 29, ꢀ16 to 0,
ꢀ25 to 0
Reflections collected/
unique
Completeness to q¼27.50
Absorption correction
Refinement method
14,311/13,638
[R(int)¼0.0345]
99.5%
27,350/10,121
[R(int)¼0.0977]
99.5%
61,173/17,064
[R(int)¼0.0809]
99.7%
12,250/11,907
[R(int)¼0.0659]
99.7%
None
Full-matrix
None
Full-matrix least-squares
None
Full-matrix
None
Full-matrix least-squares
least-squares on F2
13,638/0/974
on F2
10,121/6/667
least-squares on F2
17,064/56/1188
on F2
11,907/26/685
Data/restraints/
parameters
Goodness-of-fit on F2
Final R indices [I>2s(I)]
R indices (all data)
Largest diff. peak and
1.014
1.247
0.992
0.885
R1¼0.0957, wR2¼0.2719
R1¼0.2252, wR2¼0.3585
0.738 and ꢀ0.421
R1¼0.1579, wR2¼0.3788
R1¼0.2362, wR2¼0.4298
1.710 and ꢀ0.770
R1¼0.0703, wR2¼0.1788
R1¼0.1507, wR2¼0.2328
0.730 and ꢀ0.486
R1¼0.0886, wR2¼0.2301
R1¼0.3078, wR2¼0.3269
0.446 and ꢀ0.445
ꢀ3
˚
hole (eA
)
Weighting scheme: w¼1/[s2(Fo2)+(0.1660P)2+0.0000P], where P¼(Fo2+2F2c)/30.

2282
J. Han et al. / Tetrahedron 63 (2007) 2275–2282
CH3). 13C NMR (CDCl3) d: 13.5, 13.8, 68.1, 68.3, 68.6, 68.7,
68.9, 69.0, 69.1, 69.2, 110.3, 144.0, 151.9, 168.4. Anal.
Calcd for C124H120Fe4N16O16: C, 64.37; H, 5.23; N, 9.69.
Found: C, 64.58; H, 5.65; N, 9.41.
9. Beer, P. D.; KeefeMichael, A. D.; Drew, G. B. J. Organomet.
Chem. 1988, 353, C10.
10. Beer, P. D.; Keefe, A. D.; Slawin, A. M. Z.; Drew, M. G. B.
J. Chem. Soc., Dalton Trans. 1990, 3675.
11. Beer, P. D.; Tite, E. L.; Ibbotson, A. J. Chem. Soc., Dalton
Trans. 1991, 1691.
3.6. Electrochemical analysis
12. Beer, P. D.; Keefe, A. D. J. Inclusion Phenom. 1987, 5, 499.
13. Beer, P. D.; Chen, Z.; Drew, M. G. B.; Gale, P. A. J. Chem. Soc.,
Chem. Commun. 1995, 1851.
14. Beer, P. D.; Chen, Z.; Goulden, A. J.; Graydon, A.; Stockes,
S. E.; Wear, T. J. Chem. Soc., Chem. Commun. 1993, 1834.
15. Beer, P. D.; Drew, M. G. B.; Hazlewood, C.; Hesek, D.;
Hodacova, J.; Stockes, S. E. J. Chem. Soc., Chem. Commun.
1993, 229.
16. Beer, P. D.; Hesek, D.; Kingston, J. E.; Smith, D. K.; Stockes,
S. E.; Drew, M. G. B. Organometallics 1995, 14, 3288.
17. Beer, P. D.; Drew, M. G. B.; Ibbotson, A.; Tite, E. L. J. Chem.
Soc., Chem. Commun. 1988, 1498.
E
1/2(Epa) versus Fc+/Fc was estimated by cyclic voltammet-
ric method using platinum disc electrode as a working elec-
trode, platinum wire as a counter electrode, and SCE as
a reference electrode; the solution (0.5 mM) was dissolved
in CH2Cl2 using 0.1 M Bu4NClO4 (TBAP) as a supporting
electrolyte with a scan rate of 50 mV sꢀ1 and all the poten-
tials were calibrated and referenced with ferrocene (E1/2
(Fc/Fc+)¼0.49 V vs SCE) as an internal standard.
3.7. X-ray structure determination
18. Gale, P. A.; Chen, Z.; Drew, M. G. B.; Heath, J. A.; Beer, P. D.
Polyhedron 1998, 17, 405.
19. Dumazet, I.; Beer, P. D. Tetrahedron Lett. 1999, 40, 785.
20. Beer, P.D.;Gale,P. A.;Hesek,D.TetrahedronLett.1995, 36, 767.
21. Tomapatanaget, B.; Tuntulani, T.; Chailapakul, O. Org. Lett.
2003, 5, 1539.
22. Tomapatanaget, B.; Tuntulani, T. Tetrahedron Lett. 2001, 42,
8105.
23. Beer, P. D.; Drew, M. G. B.; Hesek, D.; Shade, M.; Szems, D.
Chem. Commun. 1996, 2161.
The procedure of crystal structure determination for both 2a–
2c and 4d was the same. X-ray data were collected at
293(2) K on a Bruker diffractometer using Mo Ka X-ray
˚
(0.71069 A) source and a graphite monochromator. The
unit cell dimensions were obtained from a least-squares fit
to setting angles of 25ꢂ reflections. Psi scan absorption cor-
rections were applied. The structures were solved by direct
methods using CRYSTAL STRUCTURE and refined by
full-matrix least square method using SHELXL97. In the
final step of refinement procedure, all non-hydrogen atoms
were refined with anisotropic displacement parameters. A
summary of crystallographic relevant data is given in Table 2.
24. Beer, P. D.; Drew, M. G. B.; Hesek, D.; Nam, K. C. Chem.
Commun. 1997, 107.
25. Beer, P. D.; Drew, M. G. B.; Hesek, D.; Nam, K. C.
Organometallics 1999, 18, 3933.
3.8. Supplementary material
26. Cooper, J. B.; Drew, M. G. A.; Beer, P. D. J. Chem. Soc., Dalton
Trans. 2000, 2721.
27. Beer, P. D.; Hayes, E. J. J. Coord. Chem. Rev. 2003, 240, 131.
28. Bondy, C. R.; Beer, P. D.; Loeb, S. J. Coord. Chem. Rev. 2003,
240, 77.
Single crystal X-ray diffraction data are deposited at CCDC
(deposition numbers 2a: 622100; 2b: 622101; 2c: 622102;
4d: 622103).
29. Reynes, O.; Maillard, F.; Moutet, J. C.; Royal, G.; Saint-Aman,
E.; Stanciu, G.; Dutasta, J. P.; Gosse, I.; Mulatier, J. C.
J. Organomet. Chem. 2001, 356, 637.
30. Valero, C.; Fillut, J. L.; Ruiz, J.; Guittard, J.; Blais, J. C.;
Astruc, D. J. Am. Chem. Soc. 1997, 119, 2588.
31. Beer, P. D.; Cadman, J.; Lloris, J. M.; Martinez-Manez, R.;
Soto, J.; Pardo, T.; Marcos, M. D. J. Chem. Soc., Dalton
Trans. 2000, 1805.
Acknowledgements
This work was financially supported by the National Natural
Science Foundation of China (Grant No. 20672091) and
the Jiangsu Provincial Key Program of Physical Chemistry
in Yangzhou University, China. We are also grateful to
Ms. Min Shao for assistance with measuring the single crys-
tal structures.
32. Atwood, J. L.; Szumna, A. Chem. Commun. 2003, 940.
33. Botta, B.; Caporuscio, F.; Subissati, D.; Tafi, A.; Botta, M.;
Filippi, A.; Speranza, M. Angew. Chem., Int. Ed. 2006, 45, 2717.
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