Synthesis, structure and properties of the macrocyclic ferrocenophanes with cyclopentadienyl ligands tethered by oligo(ethylene glycol) chain

Article abstract of DOI:10.1016/j.jorganchem.2010.07.028

Cyclization reactions of Fe{C₅H₄OCH ₂(CH₂OCH₂)_nCH₂OTs} ₂ (n = 1, 2) with C₆H₄-1,2-(OH)₂, C₆H₄-1,3-(OH)₂, and Fe(C₅H ₄OAc)₂ under basic conditions yield the corresponding macrocyclic 1,1′-ferrocenophanes. The ferrocenophane having a pyrido-crown ether structure was also synthesized. These ferrocenophanes were characterized by X-ray crystallography and NMR spectroscopy. Cyclic voltammograms of the ferrocenophanes exhibited reversible redox peaks assigned to the oxidation and reduction of the ferrocene unit. The macrocyclic pyrido-containing ferrocenophane forms pseudorotaxane with [NH₂{(CH₂) ₉Me}₂]BARF (BARF = B{C₆H₃-3,5- (CF₃)₂}₄) in CDCl₃.

Full text of DOI:10.1016/j.jorganchem.2010.07.028

Journal of Organometallic Chemistry 695 (2010) 2512e2518
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, structure and properties of the macrocyclic ferrocenophanes
with cyclopentadienyl ligands tethered by oligo(ethylene glycol) chain
*
Yuji Suzaki, Atsuko Takagi, Kohtaro Osakada
Chemical Resources Laboratory (Mail Box R1-3), Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Cyclization reactions of Fe{C5H4OCH2(CH2OCH2)nCH2OTs}2 (n ¼ 1, 2) with C6H4-1,2-(OH)2, C6H4-1,3-
(OH)2, and Fe(C5H4OAc)2 under basic conditions yield the corresponding macrocyclic 1,10-ferroceno-
phanes. The ferrocenophane having a pyrido-crown ether structure was also synthesized. These
ferrocenophanes were characterized by X-ray crystallography and NMR spectroscopy. Cyclic voltam-
mograms of the ferrocenophanes exhibited reversible redox peaks assigned to the oxidation and
reduction of the ferrocene unit. The macrocyclic pyrido-containing ferrocenophane forms pseudor-
otaxane with [NH2{(CH2)9Me}2]BARF (BARF ¼ B{C6H3-3,5-(CF3)2}4) in CDCl3.
Received 12 June 2010
Received in revised form
24 July 2010
Accepted 29 July 2010
Available online 6 August 2010
Keywords:
Ferrocene
Ó 2010 Elsevier B.V. All rights reserved.
Ferrocenophane
Crown ether
Electrochemistry
1. Introduction
R
BARF-
O
O
O
Ferrocenophanes, ferrocene derivatives whose cyclopentadienyl
ligands were connected by bridging unit, have received attention
due to their unique propertied such as the intramolecular elec-
tronic communication, the ligandation to the transition metals and
their ring-opening polymerization [1e5]. Macrocyclic ferroceno-
phanes having oligo(ethylene glycol) units as the tether of the
cyclopentadienyl ligands were regarded as analogues to the crown
ethers and have been reported to include metal cations as the
host molecule [6]. The affinity to the metal cations varies
depending on the length of the oligo(ethylene glycol) tether,
oxidation state of the Fe atom, and the presence of a heteroatom
within the ring [6e8].
O
O
+
O
N
O
O
H2
Fe
O
O
O
BARF = B{C6H3-3,5-(CF3)2}4
R
O
O
(1)
O
O
O
+
BARF-
k
obs
O
+
N
H2
CD3CN
O
Fe
O
O
O
O
Recently we have reported a macrocyclic octaoxa[22]ferroce-
nophane and its rotaxane with dialkyl ammonium [9]. The
rotaxane undergoes disaggregation reaction in CD3CN (kobs ¼ 3.9
(7) ꢀ 10ꢁ6 sꢁ1 at 45 ꢂC) (Eq (1)), although the rotaxane having
DB24C8 (dibenzo[24]crown-8) as a macrocyclic component is
stable in solution under the same conditions. It is probably
assigned to the larger size of the cavity of the octaoxa[22]ferro-
cenophane than that of DB24C8. The macrocyclic structures of
these 1,10-ferrocenylene-containing crown ethers were considered
(kobs = 3.9(7) x 10-6 /s-1, at 45 oC)
Fe
R =
,
(No reaction)
to influence the formation of the hosteguest complexes with the
cationic ions or molecules. Akabori reported detailed structure of
the complex of a pentaoxa[13]ferrocenophane and NaSCN [6e]. In
this paper we report preparation of macrocyclic 1,10-ferroceno-
phanes as well as their structures in the solid state, electro-
chemical properties, and pseudorotaxane formation in solution.
* Corresponding author. Tel./fax: þ81 45 924 5224.
E-mail address: kosakada@res.titech.ac.jp (K. Osakada).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.07.028

Y. Suzaki et al. / Journal of Organometallic Chemistry 695 (2010) 2512e2518
2513
OCH2(CH2OCH2)nCH2OTs
OCH2(CH2OCH2)nCH2OTs
A
Fe
C H
5
4
OCH
2
+ OCH
2
(n = 1, 2; Ts = SO2C6H4-4-Me)
*
C H
5
4
C6H4(OH)2
O
O
n
(or Fe(C5H4OAc)2)
O
O
base
Fe
(2)
R
OCH
O
O
2
DMF
B
BARF
*
C H
5
4
n
1: n = 1, R = C6H4-1,2-
2: n = 1, R = C6H4-1,3-
3: n = 1, R = Fe(C5H4)2
4: n = 2, R = C6H4-1,2-
5: n = 2 R = Fe(C5H4)2
δ
8
6
4
Fig. 1. 1H NMR spectra (300 MHz, CDCl3, r.t.) of (A) 3 ([3] ¼ 10 mM) and (B) 3 and
NaBARF ([3] ¼ [NaBARF] ¼ 10 mM). Peaks with asterisk indicate CHCl3.
2. Results and discussion
magnetic field position (
d
4.01, 4.33) and of C5H4 (
d
3.86e3.89, 4.11)
Macrocyclic 1,10-ferrocenophanes, 1e3 and 5, were newly
prepared, although 4 was already reported elsewhere [9]. Fe
{C5H4OCH2(CH2OCH2)nCH2OTs}2 (n ¼ 1, 2; Ts ¼ SO2C6H4-4-Me) is
to the higher magnetic field positions (
d 3.71, 3.92). FABMS of the
mixture shows a peak at m/z ¼ 599 corresponding to [3 þ Na]þ.
These results indicate that 3 and Naþ form the 1:1 inclusion
complex in CDCl3 solution [6,10].
synthesized by reaction of TsCl and Fe{C5H4OCH2(CH2OCH2)n
-
CH2OH}2 (n ¼ 1, 2) and used for the cyclization shown in Eq (2).
Reaction of Fe(C5H4OCH2CH2OCH2CH2OTs)2 and C6H4-1,2-(OH)2
with K2CO3 in DMF for 7 days yields 1 having a hexaoxa[16]ferro-
cenophane structure (Table 1). FABMS (Fast atom bombardment
mass spectrum) of 1 shows a peak at m/z ¼ 468 corresponding to
Reaction of Fe(C5H4OCH2CH2OCH2CH2OH)2 with C5H3N-2,6-
(CH2OTs)2 in the presence of NaH ([Fe(C5H4OCH2CH2OCH2
CH2OH)2] ¼ [C5H3N-2,6-(CH2OTs)2] ¼ 5 mM) forms the cyclization
product 6 in 18% isolated yield (Eq (3)). 13C{1H} NMR spectrum of 6
shows signals for the cyclopentadienyl carbons at
d 56.0, 62.9 and
the structure. 13C{1H} NMR of 1 contains signals of C5H4 units (
d
128.8. FABMS of 6 shows a peak at m/z ¼ 497 corresponding to the
56.1, 61.8, 126.7). Similar cyclization reactions yield ferrocene-
containing crown ether 2e5 in 8e88% (Eq (2), Table 1). The reac-
tions of Fe(C5H4OCH2CH2OCH2CH2OTs)2 with C6H4-1,2-(OH)2 and
C6H4-1,3-(OH)2 in the presence of K2CO3 yield 1 and 2 in higher
yield (1:58%, 2:20%) than those with Cs2CO3 (1:43%, 2:13%). The
difference in the yields was attributed to the template effect of the
macrocycle to inclusion of metal cations, Kþ or Csþ, which facili-
tates the cyclization.[10] Ferrocenophanes 3 and 5 were synthe-
sized from the reaction of Fe{C5H4OCH2(CH2OCH2)nCH2OTs}2
(n ¼ 1, 2) with [Fe(C5H4O)2]2ꢁ, generated in situ from Fe(C5H4OAc)2,
Cs2CO3 and KOH in water. 13C{1H} NMR spectrum of 3 contains
calculated molecular weight.
TsO
OCH2CH2OCH2CH2OH
Fe
+
N
OCH2CH2OCH2CH2OH
TsO
(3)
O
O
O
O
O
O
NaH
N
Fe
THF
reflux
18%
three signals for C5H4 (d 56.2, 62.1, 127.0) and two signals for OCH2
(d 70.1 (overlapping)) due to the symmetric structure composed of
two 1,10-ferrocenylenes and two di(ethylene glycol) units. 1H NMR
6
spectrum of 3 in CDCl3 shows the two signals of the C5H4 hydrogens
(d 3.86e3.89, 4.11) as well as the two signals of OCH2 (d 3.86e3.89,
Recrystallization of 1, 2 and 3 gave the single crystals suitable for
X-ray structure analysis. Complexes of 5 with KBPh4 and of 6 with
NaBARF were also characterized by X-ray crystallography. The
obtained molecular structures were shown in Fig. 2. C(C5H4)eO
bonds of 1 (C5eO1 and C20eO6) adopt almost eclipsed conforma-
tion to the axis of the ferrocene unit (Chart 1(A), Table 2). The
dihedral angle of the bonds, C5eO1 and C20eO6, is 16ꢂ.
The conformations of C5eO1eC6 and C20eO6eC19 units avoid the
electrostatic repulsion of the lone pairs of O1 and O6. Cyclo-
pentadienyl ligands of 1 are deviated by 6.1(1)ꢂ from the ideal
parallel conformation (Chart 1(B)) which is partly ascribed to the
repulsion of O1 and O6. H8 atom of 1 has a contact with O3 (2.536 Å)
which is shorter than the sum of the van der Waals radii for oxygen
and hydrogen (2.72 Å), indicating the intramolecular hydrogen bond.
Dihedral angles of C5H4 and C6H4 are almost vertical (86.33(9)ꢂ and
88.06(9)ꢂ). Distance between Fe1 and the centroid of C6H4 is 10.053
(1) Å. The circumferential bond lengths, the sum of the bond lengths
of the macrocycle unit containing Fe1eC5eO1e through
4.06) as shown in Fig. 1(A). Addition of NaBARF (BARF ¼ B{C6H3-
3,5-(CF3)2}4) to a CDCl3 solution of 3 ([3] ¼ [NaBARF] ¼ 10 mM)
causes shift of the signals of OCH2 (d 3.86e3.89, 4.06) to lower
Table 1
Conditions and yields of macrocyclic ferrocenophanes, 1e6.
Compound
n
1
R
Base
Time
Isolated Yields
1
C6H4-1,2-
K2CO3
Cs2CO3
K2CO3
Cs2CO3
Cs2CO3/KOH
Cs2CO3
Cs2CO3/KOH
NaH
7 days
4 days
3 days
3 days
7 h
3 days
19 h
2 days
58%
43%
20%
13%
8%
88%
33%
18%
2
1
C6H4-1,3-
3
Fe(C5H4)2
C6H4-1,2-
Fe(C5H4)2
e
1
4a
5
2
2
6b
e
a
Ref. [9].
b
See Eq. (3) and experimental section for the structure of the compounds and
reaction conditions.

2514
Y. Suzaki et al. / Journal of Organometallic Chemistry 695 (2010) 2512e2518
A
C6
C19
O6
O1
C20
C5
Fe
B
O1
O6
6.1(1)o
Fe
Chart 1. Conformation of cyclopentadienyl ligands of 1 obtained from X-ray crystal
analysis.
the cationic part of [K(5)]BPh4. K1 atom was incorporated in the
cavity of the two tri(ethylene glycol) units with helixed confor-
mation. The distances between K1 and oxygen atoms of 5 (O1eO8)
is in the range of 2.819(2)e2.888(2) Å. The atoms K1, Fe1 and Fe2
are arranged almost linearly, and K1 is located at the midpoint of
Fe1 and Fe2 (distances: Fe1/K1, 4.122(1) Å, Fe2/K1, 4.114(1) Å;
angle: Fe1/K1/Fe2, 174ꢂ). The dihedral angle of the cyclo-
pentadienyl ligands between two ferrocenylene units is 57ꢂ
(average). Fig. 2(E) shows the molecular structure of cationic part of
[Na(6)]BARF. Na atom was incorporated in the cavity of 6. The
distance between Na1 and oxygens of 6 (O1eO6) is in the range of
2.419(2)e2.654(2) Å. The nitrogen atom of 6 coordinates to the Na
atom (distance: Na1eN1, 3.914(1) Å; angle: Na1eN1/Centroid of
C5H3N, 177ꢂ). Fe1 is separated from Na1 (distance: Fe1/Na1, 3.914
(1) Å), indicating little interaction between them. The dihedral
angle of C5eO1 and C21eO6 bond is 50ꢂ.
In all the macrocyclic ferrocenophanes, cyclopentadienyl
ligands of the ferrocenylene unit are in the eclipsed conformation
(tilt angle: 0.9e14.5ꢂ) and the bond angles of C(C5H4)eO bonds
were in the range of 16ꢂe72ꢂ. The cyclopentadienyl ligands were
almost parallel in 2, 3, 4, [K(5)]BPh4 and [Na(6)]BARF. The
circumferential bond lengths were varied from 28.42(5) Å to 39.7
(1) Å depending on the ethylene glycol, the 1,10-ferrocenylene, and
the pyrido units[11,12]. Replacement of a C6H4-1,2- in the benzo-
crown ether by a 1,10-ferrocenylene unit causes the enlargement of
the circumferential bond lengths by ca. 2.7 Å.
Ferrocene-containing crown ethers, 1e6, undergo electro-
chemical oxidation and reduction at E1/2 ¼ ꢁ0.19 to ꢁ0.21 V (vs.
Fcþ/Fc, Fc ¼ ferrocene). The redox potentials of the compounds
determined by cyclic voltammetry (CV) are summarized in Table 3.
The lower redox potentials of ferrocene-containing crown ethers
were ascribed to the electron donation from the alkoxy groups to
stabilize the Fe(III)þ. Fig. 3 depicts cyclic voltammograms of 1 and 3
in MeCN. Both the compounds show one pair of peaks assigned to
the redox of ferrocenylene units. The larger peaks of 3 than those of
1 indicate the oxidation and reduction of the two ferrocenylene
units of 3 at the same potential and no interaction between the
Fe centers. Similar redox peaks were observed also in the cyclic
voltammogram of 5 (E1/2 ¼ ꢁ0.20 V).
Fig. 2. Molecular structure of (A) 1, (B) 2, (C) 3, (D) [K(5)]BPh4, and (E) [Na(6)]BARF.
ORTEP drawings are shown in 50% probability except [Na(6)]BARF (30%). Hydrogen
atoms and counter anions were omitted for simplicity.
eO6eC20eFe1, is 28.42(5) Å which is longer than that of DB18C6
(dibenzo[18]crown-6, 25.8(2) Å) by 2.6 Å (Table 2)[11].
The compounds 2, 3, [K(5)]BPh4 and [Na(6)]BARF were analyzed
similarly. Intramolecular hydrogen bonds were observed in 2,
C1eH1/O4 (distance: 2.694 Å; angle: 144ꢂ) and C15eH16/O1
(distance: 2.600 Å; angle: 156ꢂ), and in 3, C4-H4/O5 (distance:
2.725 Å; angle: 154ꢂ) and C18-H20/O2 (distance: 2.684 Å; angle:
153ꢂ) (Fig. 2(B) and (C)). Fig. 2(D) shows the molecular structure of
Formation of pseudorotaxane of 6 with di(alkyl)ammonium,
[NH2{(CH2)9Me}2]BARF, was investigated by FABMS and 1H NMR
spectroscopy (Scheme 1). FABMS of the product obtained from the
equimolar mixture of 6 and [NH2{(CH2)9Me}2]BARF in CDCl3

Y. Suzaki et al. / Journal of Organometallic Chemistry 695 (2010) 2512e2518
2515
Table 2
Selected distances, bond angles of macrocyclic ferrocenophanes and crown ethers.
Compound
Angle of C(C5H4)eO bonds
Dihedral angle of
Circumferential bond
length/Å
Conformation of C5H4 planes
a
C5H4 planes/ꢂ
)
(Tilt angleb)
1
2
3
16ꢂ
62ꢂ
72ꢂ
72ꢂ
50ꢂ
57ꢂ
58ꢂ
50ꢂ
e
6.1(1)
ꢁ1.60(8)
ꢁ2.55(7)
ꢁ3.63(7)
3.92(9)
1.1(2)
2.1(1)
1.6(1)
e
28.42(5)
29.72(4)
31.1(4)
eclipsed (8.7ꢂ)
eclipsed (0.9ꢂ)
eclipsed (1.2ꢂ)
4
5
37.02(8)
39.7(1)
eclipsed (14.5ꢂ)
eclipsed (8.4ꢂ, 9.3ꢂ)
6
32.47(8)
25.8(2)
34.16(6)
eclipsed (6.0ꢂ)
e
DB18C6c
DB24C8d
e
e
e
a
The deviations from the ideal parallel conformation.
The deviations from the ideal eclipsed conformation.
Ref. [11].
Ref. [12].
b
c
d
Table 3
-
BARF
Redox potential of macrocyclic ferrocenophanes.a
+
6
+
Me(CH )
N
H
(CH ) Me
2 8
Compound
Epa/V
Epc/V
E1/2 (D
Eb)/V
2 8
2
1
2
ꢁ0.17
ꢁ0.18
ꢁ0.13
ꢁ0.18
ꢁ0.16
ꢁ0.15
ꢁ0.24
ꢁ0.25
ꢁ0.25
ꢁ0.24
ꢁ0.23
ꢁ0.28
ꢁ0.21 (0.07)
ꢁ0.21 (0.07)
ꢁ0.19 (0.12)
ꢁ0.21 (0.06)
ꢁ0.20 (0.07)
ꢁ0.21 (0.13)
Fe
3
-
4c
5
BARF
O
O
+
Me(H C)
N
(CH ) Me
2 8
2
8
6
O
O
H
2
a
Electrochemical potentials are obtained by cyclic voltammetry (CV) in MeCN
containing nBu4NPF6 as the electrolyte. Potentials are referenced with Fcþ/Fc
O
O
CDCl
3
N
(Fc ¼ Fe(C5H5)2). Sweep rate: 0.10 V sꢁ1
.
b
D
E ¼ Epa ꢁ Epc
.
c
[(6){NH ((CH ) Me) }]BARF
Ref. [9].
2
2 9
2
Scheme 1. Formation of pseudorotaxane of 6 and [NH2{(CH2)9Me}2]BARF.
contains a peak at m/z ¼ 796 which is corresponding to the cationic
pseudorotaxane, [(6){NH2((CH2)9Me)2}]þ. Addition of 6 to a CDCl3
the hydrogen bonds between NCH2 and NH2 hydrogen of
[NH2{(CH2)9Me}2]BARF and the oxygens and nitrogen of 6[14].
The mixture of 6 and [NH2{(CH2)9Me}2]BARF shows the signals
solution of [NH2{(CH2)9Me}2]BARF ([6]
¼
[[NH2{(CH2)9Me}2]
BARF] ¼ 10 mM) causes shift of the 1H NMR signals of NCH2 (
d 2.94)
and NH2
(d
5.88) hydrogens to the lower magnetic field positions
of the hydrogen at C6H3N-CH2 and 3-position of C6H3N of 6 (
7.19) and the sharp cyclopentadienyl hydrogen signals ( 3.80, 3.90)
(Fig. 4(C)), while free 6 shows the former signals at lower positions
4.72, 7.34) and as broad signals due to the cyclopentadienyl
hydrogens (
4.03, 4.24). The difference in the 1H NMR signals
d 4.55,
(
d
3.38 (NCH2), 7.92 (NH2)) (Fig. 4(A) and (B)). Cooling the solution
d
to ꢁ50 ꢂC causes further shift of the NH2 hydrogen peak to
d 8.42.
The molar ratio of [(6){NH2((CH2)9Me)2}]BARF to [NH2{(CH2)9Me}2]
BARF at ꢁ50 ꢂC was estimated to 87/13, based on the signal of the
NCH2 hydrogens. The shifts of the signals of [(6){NH2((CH2)9Me)2}]
BARF from those of [NH2{(CH2)9Me}2]BARF were ascribed to
(d
d
between the complexed and uncomplexed macrocycle is ascribed
to the restricted ring motion in ferrocene unit in pseudorotaxane
[(6){NH2((CH2)9Me)2}]BARF. The association constant Ka (5.1 ꢀ
103 Mꢁ1 at 25 ꢂC) is obtained from the 1H NMR and found to be
larger than that of the complex of P21C7 (pyrido[21]crown-7) and
(A)
(B)
4 μA
-0.4
0
0.4
E/V vs Fc+/Fc
Fig. 4. 1H NMR spectra (300 MHz, CDCl3, 25 ꢂC) of (A) [NH2{(CH2)9Me}2]BARF, (B) 6
and [NH2{(CH2)9Me}2]BARF (10 mM for each), and (C) 6. Peaks with asterisk indicate
CHCl3.
Fig. 3. Cyclic voltammograms in MeCN containing 0.10 M nBu4NPF6 at 25 ꢂC. Sweep
rate: 0.10 V sꢁ1. (A) 1 (1.0 mM) and (B) 3 (1.0 mM).

2516
Y. Suzaki et al. / Journal of Organometallic Chemistry 695 (2010) 2512e2518
[NH2(nBu)2]PF6 in acetone-d6 (Ka ¼ 1625 Mꢁ1 at 22 ꢂC)[13]. Stod-
dart et al. investigated complexation of DB24C8 and di(n-alkyl)
ammonium with PFꢁ6 anion in CDCl3 and concluded that low
solubility of the dialkylammonium in the less polar solvent pre-
vented determination of precise association constant[15]. Since di
(alkyl)ammonium with BARF counter anion used in this study is
soluble in CDCl3 and forms an equilibrated mixture with the [2]
pseudorotaxane, the 1H NMR data gives the reliable association
constants in CDCl3. Similar pseudorotaxane formation of
[NH2{(CH2)9Me}2]BARF with 1e3 and 5 was not observed in both in
1H NMR spectroscopy and in FABMS measurement.
In summary, we report the synthesis of macrocyclic ferroceno-
phanes which were analyzed by X-ray crystallography. The crown
ethers with various ring sizes were obtained depending on the
numbers of ethylene glycol units as well as the 1,10-ferrocenylene,
C6H4 and pyrido units. The obtained ferrocene-containing crown
ethers exhibit reversible oxidation and reduction of the Fe(II)
center at lower potentials than that of unsubstituted ferrocene. The
macrocyclic ferrocenophanes having a pyrido group showed func-
tion as a host molecule for the dialkylammonium to form a pseu-
dorotaxane type complex in solution.
r.t.): d 55.9 (C5H4), 61.4 (CH2), 62.3 (C5H4), 69.6 (CH2, 2 signals), 72.6
(CH2), 126.5 (C5H4).
3.3. Fe(C5H4OCH2CH2OCH2CH2OTs)2
NaOH (0.15 g, 3.3 mmol) and TsCl (0.26 g, 1.3 mmol) was added
to
a
solution (THF/H2O
¼
0.6 mL/0.1 mL) of Fe(C5H4OCH2
-
CH2OCH2CH2OH)2 (0.17 g, 0.43 mmol) at room temperature. The
solution was stirred for 21 h at room temperature followed by
addition of water and the extraction of the product with CH2Cl2.
The separated organic phase was dried over MgSO4, filtered, and
evaporated to give Fe(C5H4OCH2CH2OCH2CH2OTs)2 as orange oil
(0.30 g, 0.42 mmol, 98%). Anal. Calcd. for C32H38FeO10S2(H2O): C,
53.33; H, 5.59. Found: C, 53.25; H, 5.56; 1H NMR (300 MHz, CDCl3,
r.t.):
d 2.42 (s, 6H, CH3), 3.68e3.75 (m, 8H, CH2), 3.83e3.85 (m, 4H,
C5H4), 3.89e3.92 (m, 4H, CH2), 4.07e4.08 (m, 4H, C5H4), 4.16e4.19
(m, 4H, CH2), 7.32 (d, 4H, C6H4, J ¼ 8 Hz), 7.79 (d, 4H, C6H4, J ¼ 8 Hz);
13C{1H} NMR (75.5 MHz, CDCl3, r.t.):
d 21.5 (CH3), 55.8 (C5H4), 62.3
(C5H4), 68.6 (CH2), 69.1 (CH2), 69.5 (CH2), 69.8 (CH2), 126.4 (C5H4),
127.8 (C6H4), 129.7 (C6H4), 132.5 (C6H4), 144.7 (C6H4).
3.4. Ferrocenophane 1
3. Experimental
A DMF solution (20 mL) containing Fe(C5H4OCH2CH2OCH2
-
CH2OTs)2 (0.23 g, 0.33 mmol) and ortho-catechol (36 mg,
0.33 mmol) was added dropwise to the DMF suspension (20 mL) of
K2CO3 (0.46 g, 3.3 mmol) at 80 ꢂC. The resulting solution was stirred
for 7 days at 80 ꢂC followed by evaporation. The obtained brown oil
was dissolved in CH2Cl2 and the solution was washed with satu-
rated NH4Cl(aq). The separated organic phase was dried over
MgSO4, filtered and evaporated to form yellow oil. The crude
product was purified by SiO2 column chromatography (CH2Cl2,
Rf ¼ 0.09) to give 1 as yellow solid (90 mg, 0.19 mmol, 58%). Anal.
Calcd. for C24H28FeO6: C, 61.55; H, 6.03. Found: C, 61.43; H, 5.68;
FABMS: Calcd. for C24H28FeO6: 468. Found: m/z ¼ 468; 1H NMR
3.1. General
Fe{C5H4OCH2(CH2OCH2)2CH2OTs}2[9],
C5H3N-2,6-(CH2OTs)2[17], NaBARF[18], (BARF
(CF3)2}4) and 4[9] were prepared according to the literature
method. The other chemicals were commercially available. DMF
Fe(C5H4OAc)2[6c,16],
B{C6H3-3,5-
¼
and water used as solvent for preparation of Fe(C5H4OCH2
-
CH2OCH2CH2OH)2, 1, 2, 3 and 5 were degassed by N2 gas bubbling
(1 h) before use. NMR spectra (1H, 13C{1H}) were recorded on
a Varian MERCURY300. The chemical shifts were referenced with
respect to CHCl3 (d d
7.26) for 1H and CDCl3 ( 77.0) for 13C as internal
(300 MHz, CDCl3, r.t.): d 3.81e3.83 (m, 4H, C5H4), 3.96e3.99 (m, 8H,
standards. Fast atom bombardment mass spectrum (FABMS) was
obtained from JEOL JMS-700 (matrix, 2-nitrophenyloctylether).
Elemental analyses were carried out with a Yanaco MT-5 CHN
autorecorder. Cyclic voltammetry (CV) was measured in MeCN
solution containing 0.1 M nBu4NPF6 with ALS Electrochemical
Analyzer Model-600A. The measurement was carried out in
a standard one-compartment cell equipped with Agþ/Ag reference
electrode, a platinum-wire counter electrode and a platinum-disk
working electrode (ID: 1.6 mm). Thermogravity analysis (TGA) was
recorded on Seiko TG/DTA6200R. Differential scanning calorimeter
(DSC) was recorded on Seiko DSC6200S. IR absorption spectra were
recorded on Shimadzu FT/IR-8100 spectrometers.
CH2), 4.03e4.06 (m, 4H, CH2), 4.12e4.13 (m, 4H, C5H4), 4.19e4.22
(m, 4H, CH2), 6.87e6.94 (m, 4H, C6H4); 13C{1H} NMR (75.5 MHz,
CDCl3, r.t.):
d 56.1 (C5H4), 61.8 (C5H4), 69.3 (CH2), 69.8 (CH2), 70.0
(CH2), 70.6 (CH2), 113.5 (C6H4), 121.3 (C6H4), 126.7 (C5H4), 148.6
(C6H4); IR (KBr disk, r.t., in cmꢁ1): 2938, 2679, 1356, 1279, 1125; 5%
weight loss temperature: 262 ꢂC (by TGA. scan rate ¼ 5 ꢂC/min);
m.p.: 132 ꢂC (by DSC. decomp.). Similar reaction using Cs2CO3
instead of K2CO3 gave 1 in 43% yield.
3.5. Ferrocenophane 2
A DMF solution (50 mL) containing Fe(C5H4OCH2CH2OCH2
-
CH2OTs)2 (0.27 g, 0.39 mmol) and meta-resorcinol (1,3-dihydrox-
ybenzene) (46 mg, 0.39 mmol) was added dropwise to the DMF
suspension (25 mL) of K2CO3 (0.54 g, 3.9 mmol) for 6 h at 80 ꢂC. The
resulting solution was stirred for 3 days at 80 ꢂC followed by
evaporation. The obtained brown oil was dissolved in CH2Cl2 and
the solution was washed with saturated NH4Cl(aq). The separated
organic phase was dried over MgSO4, filtered and evaporated to
form yellow oil. The crude product was purified by SiO2 column
chromatography (CH2Cl2, Rf ¼ 0.36) to give 2 as yellow solid (37 mg,
0.079 mmol, 20%). Anal. Calcd. for C24H28FeO6: C, 61.55; H, 6.03
Found: C, 61.45; H, 5.90; FABMS: Calcd. for C24H28FeO6: 468. Found:
3.2. Fe(C5H4OCH2CH2OCH2CH2OH)2
The aqueous solution (40 mL) containing Fe(C5H4OAc)2 (0.73 g,
2.4 mmol), [18]crown-6 (0.021 g, 0.079 mmol) and KOH (6.9 g,
120 mmol) was refluxed for 20 min under nitrogen atmosphere. Cl
(CH2CH2O)2THP (THP ¼ 2-tetrahydropyranyl) (2.0 g, 9.6 mmol) was
added to the solution followed by further refluxing for 7 h. The
product was extracted by Et2O and the separated organic phase was
washed with NaHCO3(aq) and water then dried over MgSO4,
filtered and evaporated to give yellow oil. The crude product was
purified by SiO2 column chromatography (AcOEt, Rf ¼ 0.08) to give
Fe(C5H4OCH2CH2OCH2CH2OH)2 as yellow oil (0.24 g, 0.61 mmol,
25%). Anal. Calcd. for C18H26FeO6(H2O)0.75: C, 53.02; H, 6.80. Found:
m/z ¼ 468; 1H NMR (300 MHz, CDCl3, r.t.):
d 3.79 (t, 4H, CH2,
J ¼ 4 Hz), 3.85 (m, 8H, CH2, C5H4), 3.97 (t, 4H, CH2, J ¼ 4 Hz), 4.12
(brs, 4H, C5H4), 4.24 (t, 4H, CH2, J ¼ 5 Hz), 6.53 (dd, 2, C6H4, J ¼ 8,
2 Hz), 6.89 (t, 1H, C6H4, J ¼ 2 Hz), 7.14 (t, 1H, C6H4, J ¼ 8 Hz); 13C{1H}
C, 53.14; H, 6.58; 1H NMR (300 MHz, CDCl3, r.t.):
d 2.99 (m, 2H, OH),
3.64e3.67 (m, 4H, CH2), 3.73e3.79 (m, 8H, CH2), 3.88 (brs, 4H,
NMR (75.5 MHz, CDCl3, r.t.): d 56.3 (C5H4), 62.3 (C5H4), 68.2 (CH2),
C5H4), 3.99e4.02 (brs, 4H, C5H4); 13C{1H} NMR (75.5 MHz, CDCl3,
69.9 (CH2), 70.0 (CH2), 70.2 (CH2), 103.2 (C6H4), 108.3 (C6H4), 129.7

Y. Suzaki et al. / Journal of Organometallic Chemistry 695 (2010) 2512e2518
2517
(C6H4), 160.0 (C6H4). Similar reaction using Cs2CO3 instead of K2CO3
gave 2 in 13% yield.
3.8. Ferrocenophane 6
A THF solution (14 mL) containing Fe(C5H4OCH2CH2OCH2
-
CH2OH)2 (107 mg, 0.27 mmol) and C5H3N-2,6-(CH2OTs)2 (120 mg,
0.27 mmol) was added dropwise for 24 h to the THF solution (43 mL)
of NaH (19 mg, 0.81 mmol) under reflux. The solution was refluxed
further 2 days followed by quenching with methanol/water and
evaporation. The product was dissolved in AcOEt and the solution
was washed with saturated NaCl(aq). The separated organic phase
was dried over MgSO4, filtered and evaporated to form yellow oil
which was purified by SiO2 column chromatography (AcOEt,
Rf ¼ 0.19) and preparative HPLC (eluent: CHCl3) to give 6 as yellow
solid (23 mg, 0.048 mmol,18%). FABMS: Calcd. for C25H31FeNO6: 497.
Found: m/z ¼ 497; 1H NMR (400 MHz, CDCl3, r.t.): 3.64 (brs, 4H,
OCH2), 3.70 (m, 4H, OCH2), 3.77 (m, 4H, OCH2), 3.85 (brs, 4H, OCH2),
4.03 (brs, 4H, C5H4), 4.24 (brs, 4H, C5H4), 4.72 (s, 4H, CH2C5H3N), 7.34
(d, 2H, C3H5N-H3, J ¼ 8 Hz), 7.69 (t,1H, C3H5N-H4, J ¼ 8 Hz); 13C{1H}
3.6. Ferrocenophane 3
The water suspension (8 mL) of Cs2CO3 (0.75 g, 2.3 mmol),
KOH (0.10 g, 0.19 mmol), and Fe(C5H4OAc)2 (70 mg, 0.23 mmol)
was refluxed for 20 min under Ar atmosphere. A DMF solution
(27 mL) containing Fe(C5H4OCH2CH2OCH2CH2OTs)2 (0.16 g,
0.23 mmol) was added dropwise to the solution at 80 ꢂC. The
resulting solution was stirred for 7 h at 80 ꢂC followed by evap-
oration. The obtained brown oil was dissolved in CH2Cl2 and the
solution was washed with saturated NH4Cl(aq). The separated
organic phase was dried over MgSO4, filtered and evaporated to
form yellow oil. The crude product was purified by SiO2 column
chromatography (CH2Cl2, Rf ¼ 0.35) to give 3 as yellow oil (10 mg,
0.017 mmol, 8%). Anal. Calcd. for C28H32Fe2O6(H2O)0.25: C, 57.91;
H, 5.64. Found: C, 57.87; H, 5.30; FABMS: Calcd. for C28H32Fe2O6:
NMR (100 MHz, CDCl3, r.t.): d 56.0 (C5H4), 62.9 (C5H4), 69.8 (OCH2),
576. Found: m/z
¼
576; 1H NMR (300 MHz, CDCl3, r.t.):
69.8 (OCH2), 70.0 (OCH2), 71.0 (OCH2), 74.3 (CH2C5H3N), 121.2
(C3H5N-C3), 128.8 (C5H4), 137.1 (C3H5N-C4), 157.8 (C3H5N-C2); Anal.
Calcd. for C57H43BF24FeNNaO6 ([Na(6)]BARF): C, 49.48; H, 3.13; N,
1.01. Found: C, 49.10; H, 2.77; N, 1.00; IR data for [Na(6)]BARF (KBr
disk, r.t., in cmꢁ1): 2915, 1354, 1279, 1100e1170; 5% weight loss
temperature: 327 ꢂC (by TGA. scan rate ¼ 5 ꢂC/min).
d
3.86e3.89 (m, 16H, C5H4, CH2), 4.06 (m, 8H, CH2), 4.11 (m, 8H,
C5H4); 13C{1H} NMR (75.5 MHz, CDCl3, r.t.):
(C5H4), 70.1 (CH2, 2 signals), 127.0 (C5H4).
d 56.2 (C5H4), 62.1
3.7. Ferrocenophane 5
3.9. [NH2{(CH2)9Me}2]BARF
The water suspension (10 mL) of Cs2CO3 (1.2 g, 3.6 mmol), KOH
(0.19 g, 3.0 mmol) and Fe(C5H4OAc)2 (0.12 g, 0.36 mmol) was
refluxed for 20 min under Ar atmosphere. A DMF solution (60 mL)
containing Fe{C5H4OCH2(CH2OCH2)2CH2OTs}2 (0.28 g, 0.36 mmol)
was added dropwise to the solution at 80 ꢂC. The resulting solution
was stirred for 19 h at 80 ꢂC followed by evaporation. The obtained
brown oil was dissolved in CH2Cl2 and the solution was washed
with saturated NH4Cl(aq). The separated organic phase was dried
over MgSO4, filtered and evaporated to form 5 as yellow oil (80 mg,
0.12 mmol, 33%). The isolation of 5 was not feasible due to
decomposition during the further purification by SiO2 column
chromatography and the preparative HPLC (eluent: CHCl3). FABMS:
Calcd. for C32H40Fe2O8: 664. Found: m/z ¼ 664; 1H NMR (300 MHz,
[NH2{(CH2)9Me}2]BARF was prepared by similar method to the
literature [19]. Data of [NH2{(CH2)9Me}2]BARF: 1H NMR (300 MHz,
CDCl3, r.t.):
d
0.87 (t, 6H, CH3, J ¼ 7 Hz), 1.16e1.36 (brs, 28H, CH2),
1.51e1.62 (brs, 4H, NCH2CH2), 2.94 (m, 4H, NCH2), 5.88 (brs, 2H,
NH2), 7.56 (s, 4H, p-C6H3(CF3)2), 7.70 (s, 8H, o-C6H3(CF3)2); 13C{1H}
NMR (75.5 MHz, CDCl3, r.t.):
d 13.9 (CH3), 22.6 (CH2), 25.9 (CH2),
26.3 (CH2), 28.6 (CH2), 29.0 (CH2), 29.1 (CH2), 29.2 (CH2), 31.7 (CH2),
49.7 (NCH2), 117.6 (p-C6H3), 124.6 (q, CF3, J(FC) ¼ 273 Hz), 128.9 (q,
CCF3, J(FC) ¼ 32 Hz), 134.8 (o-C6H3), 161.7 (q, BC, J(BC) ¼ 50 Hz); IR
(neat, r.t., in cmꢁ1): 2934, 2860, 1356, 1279, 1129.
3.10. X-ray structure analyses
CDCl3, r.t.):
d 3.58e3.88 (m, 24H, CH2), 3.83e3.88 (m, 8H, C5H4),
3.92e4.04 (m, 8H, CH2), 4.09e4.18 (m, 8H, C5H4). Low stability of 5
Crystals of 1, 2 and 3 suitable for X-ray diffraction study were
obtained by recrystallization from acetone, CH2Cl2/hexane, and
in CDCl3 prevents 13C{1H} NMR measurement.
Table 4
Crystal data and details of structure refinement of 1, 2, 3, [K(5)]BPh4 and [Na(6)]BARF.
Compound
1
2
3
[K(5)]BPh4
[Na(6)]BARF
recrystallization solvent
color of crystal
formula
molecular weight
crystal system
space group
a/Å
acetone
orange
CH2Cl2/hexane
orange
C24H28FeO6
468.33
monoclinic
P21/n (No. 14)
13.994(2)
9.3331(15)
16.386(3)
e
AcOEt
orange
C28H32Fe2O6
576.25
monoclinic
P21/n (No. 14)
13.3096(7)
11.5137(6)
16.1874(12)
e
MeOH/acetone
orange
C56H60Fe2KO8
1022.69
triclinic
P1 (No. 2)
10.435(2)
14.310(3)
16.747(4)
80.722(6)
86.568(8)
85.891(7)
2458.7(10)
2
AcOEt
orange
C24H28FeO6
C57H43NO6BF24FeNa
1383.58
triclinic
P1 (No. 2)
12.527(3)
12.978(3)
18.950(5)
98.513(4)
105.126(3)
94.139(3)
2921(1)
2
468.33
monoclinic
P21/n (No. 14)
9.154(2)
13.057(3)
17.934(4)
e
b/Å
c/Å
a
/deg
/deg
b
102.716(4)
e
95.019(2)
e
92.094(4)
e
g
/deg
V/Å3
2090.9(8)
4
2131.9(6)
4
2478.9(3)
4
Z
F(000)
984.00
1.488
984.00
1.459
1200.00
1.544
1072.00
1.381
1383.58
1.573
D$c/g cmꢁ1
crystal size/mm
unique reflections
used reflections [I ꢃ 2.0
No. of variables
R
0.70 ꢀ 0.30 ꢀ 0.15
0.20 ꢀ 0.15 ꢀ 0.10
0.40 ꢀ 0.40 ꢀ 0.20
0.80 ꢀ 0.60 ꢀ 0.15
0.50 ꢀ 0.40 ꢀ 0.20
4659
4833
5389
10390
12307
s
(I)]
3448
308
0.032
3846
308
0.029
4850
357
0.027
8801
673
0.052
10566
863
0.050
Rw
0.036
0.036
0.040
0.064
0.080
good of fitness
1.01
1.02
0.96
1.04
0.90

2518
Y. Suzaki et al. / Journal of Organometallic Chemistry 695 (2010) 2512e2518
ꢀ
ꢀ
(c) A. Almássy, K. Barta, G. Franciò, R. Sebesta, W. Leitner, S Toma, Tetrahedron:
Asymmetry 18 (2007) 1893.
AcOEt, respectively. The crystal of [K(5)]BPh4 and [Na(6)]BARF was
obtained by recrystallization from the solution containing 5 and
KBPh4 and from the solution containing 6 and NaBARF in 1:1 M
ratio. All measurements were made on Rigaku AFC-10R Saturn CCD
[4] K. Osakada, T. Sakano, M. Horie, Y. Suzaki, Coord. Chem. Rev. 250 (2006) 1012.
[5] (a) I. Yamaguchi, T. Sakano, H. Ishii, K. Osakada, T. Yamamoto, J. Organomet.
Chem. 584 (1999) 213;
(b) T. Sakano, H. Ishii, I. Yamaguchi, K. Osakada, T. Yamamoto, Inorg. Chim.
Acta 296 (1999) 176;
(c) T. Sakano, M. Horie, K. Osakada, H. Nakao, Bull. Chem. Soc. Jpn. 74 (2001)
2059;
(d) M. Horie, T. Sakano, K. Osakada, H. Nakao, Organometallics 23 (2004) 18;
(e) T. Sakano, M. Horie, K. Osakada, H. Nakao, Eur. J. Inorg. Chem. (2005) 644;
(f) Y. Suzaki, M. Horie, T. Sakano, K. Osakada, J. Organomet. Chem. 691 (2006)
3403.
diffractometer with graphite monochromated Mo-K
a radiation.
Calculations were carried out by using a program package Crystal
StructureÔ for Windows [20]. Crystal data and detailed results of
refinement are summarized in Table 4. All hydrogen atoms were
included at the calculated positions with fixed thermal parameters.
[6] (a) J.F. Biernat, T. Wilczewski, Tetrahedron 36 (1980) 2521;
(b) S. Akabori, H. Fukuda, Y. Habata, M. Sato, S. Ebine, Chem. Lett. (1982) 1393;
(c) S. Akabori, Y. Habata, Y. Sakamoto, M. Sato, S. Ebine, Bull. Chem. Soc. Jpn. 56
(1983) 537;
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1459;
(e) S. Akabori, Y. Habata, M. Sato, Bull. Chem. Soc. Jpn. 57 (1984) 68.
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(b) T. Saji, I. Kinoshita, J. Chem. Soc., Chem. Commun. (1986) 716.
[8] 1,1’-Ferrocenylene-containing (pyrido)crown ethers having C5H4eCOO bonds.
(a) T. Izumi, T. Tezuka, S. Yusa, A. Kasahara, Bull. Chem. Soc. Jpn. 57 (1984) 2435;
(b) T. Izumi, S. Murakami, A. Kasahara, Bull. Chem. Soc. Jpn. 61 (1988) 3565.
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[10] C.J. Pedersen, J. Am. Chem. Soc. 89 (1967) 7017.
Acknowledgments
We thank our colleagues in the Center for Advanced Materials
Analysis, Technical Department, Tokyo Institute of Technology for
elemental analysis and for FABMS measurement. This work was
supported by a Grant-in-Aid for Scientific Research for Young
Scientists from the Ministry of Education, Culture, Sports, Science
and Technology, Japan (19750044), and by the Global COE program
“Education and Research Center for Emergence of New Molecular
Chemistry”.
[11] G.M. de Lima, J.L. Wardell, W.T.A. Harrison, Acta Crystallogr. E64 (2008)
o2001.
Appendix A. Supplementary material
[12] I.R. Hanson, D.L. Hughes, M.R. Truter, J. Chem. Soc., Perkin Trans. 2 (1976) 972.
[13] C. Zhang, K. Zhu, S. Li, J. Zhang, F. Wang, M. Liu, N. Li, F. Huang, Tetrahedron
Lett. 49 (2008) 6917.
[14] (a) G. Bottari, F. Dehez, D.A. Leigh, P.J. Nash, E.M. Pérez, J.K.Y. Wong,
F. Zerbetto, Angew. Chem. Int. Ed. 42 (2003) 5886;
CCDC nos. 787554, 787555, 787556, 787557, and 773746 con-
tain the supplementary crystallographic data for 1, 2, 3, [K(5)]BPh4
and [Na(6)]BARF, respectively. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
(b) T. Chang, A.M. Heiss, S.J. Cantrill, M.C.T. Fyfe, A.R. Pease, S.J. Rowan,
J.F. Stoddart, A.J.P. White, D.J. Williams, Org. Lett. 2 (2000) 2947;
(c) A.R. Williams, B.H. Northrop, K.N. Houk, J.F. Stoddart, D.J. Williams, Chem.
Eur. J. 10 (2004) 5406.
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