Further investigation on preparation, structure and electrochemical properties of N-alkyl- and N-aryl-2-aza-[3]-ferrocenophanes

Article abstract of DOI:10.1246/bcsj.74.2059

The reactions of 1,1′-bis(hydroxymethyl)ferrocene with amines primary atnines such as 6-aminohexanol, cyclohexylamine, 4-phenylbutylamine, 2-isopropylaniline, 4-(trifluoromethyl)benzylamine, and 1-aminomethylferrocene in the presence of [RuCl₂(PPh₃)₃] catalyst led to intermolecular condensation of the CH₂OH and NH₂ groups to afford N-alkyl- or N-aryl substituted 2-aza-[3]-(1,1′)-ferrocenophanes. Cyclic voltammograms of the obtained N-alkyl-2-aza-[3]-(1,1′)-ferrocenophanes exhibit reversible redox of the Fe center at E_1/2 = -0.01 - +0.04 V (vs Ag⁺/Ag) and subsequent irreversible oxidation of the amino group of the ligand at E_ox = 0.41-0.44 V. N-(4-Hydroxyphenyl)-2-aza-[3]-(1,1′)-ferrocenophane shows two pairs of reversible electrochemical oxidation and reduction at E_1/2 = 0.04 and 0.44 V. The latter potential is significantly lower than the corresponding electrochemical oxidation of N-aryl-2-aza-[3]-(1,1′)-ferrocenophanes (0.68-0.75 V). The N-alkyl-2-aza-[3]-(1,1′)-ferrocenophanes react with MeI to cause methylation of the amino group to produce cationic 2-aza-[3]-(1,1′)-ferrocenophanes containing a quaternary nitrogen center. The iodo counter anion is easily replaced with BF4^- or PF6^-. Cyclic voltammograms of the cationic ferrocenophanes show the redox between ferrocene and ferrocenium at E_1/2 = 0.37-0.42 V.

Full text of DOI:10.1246/bcsj.74.2059

c. Jpn.
© 2001 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 74, 2059–2065 (2001) 2059
e Chemical
ciety of Ja-
n
e Chemical
ciety of Ja-
n
Further Investigation on Preparation, Structure and Electrochemical
Properties of N-Alkyl- and N-Aryl-2-aza-[3]-ferrocenophanes
N-Alkyl-2-aza-[3]-ferrocenophanes
T. Sakano et al.
Tatsuaki Sakano, Masaki Horie, Kohtaro Osakada,* and Hidenobu Nakao†
01
59
65
SJA8
09-2673
110
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503
†Instrumentation Engineering Laboratory, National Food Research Institute, 2-1-12, Kannondai, Tsukuba 305-8642
(Received March 29, 2001)
The reactions of 1,1ꢀ-bis(hydroxymethyl)ferrocene with primary amines such as 6-aminohexanol, cyclohexy-
lamine, 4-phenylbutylamine, 2-isopropylaniline, 4-(trifluoromethyl)benzylamine, and 1-aminomethylferrocene in the
presence of [RuCl2(PPh3)3] catalyst led to intermolecular condensation of the CH2OH and NH2 groups to afford N-alkyl-
or N-aryl substituted 2-aza-[3]-(1,1ꢀ)-ferrocenophanes. Cyclic voltammograms of the obtained N-alkyl-2-aza-[3]-(1,1ꢀ)-
ferrocenophanes exhibit reversible redox of the Fe center at E1/2 = −0.01 − +0.04 V (vs Ag+/Ag) and subsequent irre-
versible oxidation of the amino group of the ligand at Eox = 0.41–0.44 V. N-(4-Hydroxyphenyl)-2-aza-[3]-(1,1ꢀ)-ferro-
cenophane shows two pairs of reversible electrochemical oxidation and reduction at E1/2 = 0.04 and 0.44 V. The latter
potential is significantly lower than the corresponding electrochemical oxidation of N-aryl-2-aza-[3]-(1,1ꢀ)-ferro-
cenophanes (0.68–0.75 V). The N-alkyl-2-aza-[3]-(1,1ꢀ)-ferrocenophanes react with MeI to cause methylation of the
amino group to produce cationic 2-aza-[3]-(1,1ꢀ)-ferrocenophanes containing a quaternary nitrogen center. The iodo
counter anion is easily replaced with BF4− or PF6−. Cyclic voltammograms of the cationic ferrocenophanes show the re-
dox between ferrocene and ferrocenium at E1/2 = 0.37–0.42 V.
01
01
.1
.2
Introduction of functional groups to cyclopentadienyl
ligands of ferrocene provides a variety of compounds which
show unique electrochemical and physical properties as poten-
tial molecular materials.1–6 We reported previously Ru com-
plex-catalyzed condensation of 1,1ꢀ-bis(hydroxymethyl)fer-
rocene with arylamines and hexylamine7–11 to produce N-aryl
(or alkyl)-2-aza-[3]-(1,1ꢀ)-ferrocenophanes in moderate to high
yields as shown in Scheme 1.12 In order to obtain further scope
and insight of the reaction and the products, we have continued
study of the condensation of 1,1ꢀ-bis(hydroxymethyl)ferrocene
with various alkylamines and the chemical and electrochemi-
cal properties of the formed ferrocenophanes. Here we report
preparation of several new N-alkyl-2-aza-[3]-(1,1ꢀ)-ferro-
cenophanes and related compounds, as well as results of rein-
vestigation of their structures and electrochemical behavior,
and compare the results with those for analogous N-aryl-2-aza-
[3]-(1,1ꢀ)-ferrocenophanes reported previously.
rocenophanes 1–3 as shown in Eq. 1.
(1)
Similar reactions of 2-isopropylaniline and of 4-(trifluorome-
thyl)benzylamine also form the N-substituted-2-aza-[3]-(1,1ꢀ)-
ferrocenophanes 4 and 5, respectively. Ferrocenophane 6, hav-
ing ferrocenylmethyl group at the nitrogen, is obtained from
the reaction of 1-aminomethylferrocene with 1,1ꢀ-bis(hy-
droxymethyl)ferrocene. Table 1 summarizes results of the re-
actions. Yields of 1 and 2 (19% and 30%) as well as that of N-
hexyl-2-aza-[3]-(1,1ꢀ)-ferrocenophane (40%)12 are lower than
those of N-arylated azaferrocenophane from similar reactions
reported previously (56–68%).12 Although 6-aminohexanol
causes not only condensation of the NH2 group with 1,1ꢀ-
bis(hydroxymethyl)ferrocene but also undesired self-conden-
sation of the NH2 and OH groups, the product 1 can be isolated
in a pure form after purification by column chromatography
Results and Discussion
Alkylamines such as 6-aminohexanol, cyclohexylamine,
and 4-phenylbutylamine react with 1,1ꢀ-bis(hydroxymeth-
yl)ferrocene in the presence of [RuCl2(PPh3)3] catalyst at 180
°C to produce the corresponding N-alkyl-2-aza-[3]-(1,1ꢀ)-fer-
Scheme 1.

2060 Bull. Chem. Soc. Jpn., 74, No. 11 (2001)
N-Alkyl-2-aza-[3]-ferrocenophanes
Table 1. Yields and Analytical Data of N-Substituted-2-aza-[3]-(1,1ꢀ)-ferrocenophanes
Product
Amine
Yielda)
Color
Elemental Analysisb)
R in RNH2
-(CH2)6-OH
-cyclo-C6H11
-(CH2)4Ph
%
19
30
56
32
35
49
C
H
N
1
2
3
Yellow 65.80 (66.07) 6.42 (7.70) 4.33 (4.28)
Yellow 70.26 (69.91) 7.30 (7.50) 4.34 (4.53)
Yellow 72.99 (73.54) 7.08 (7.01) 3.82 (3.90)
Orange 73.28 (73.05) 7.00 (7.01) 3.85 (3.90)
Orange 62.07 (62.36) 4.84 (4.71) 3.56 (3.64)
Orange 64.71 (64.98) 5.28 (5.45) 3.02 (3.29)
4
-C6H4-o-iPr
-CH2C6H4CF3
-CH2Fcd)
5c)
6
a) Isolated yield after purification by column chromatography and/or recrystallization.
b) Required values are given in parenthesis. c) F: 14.79 (14.50) d) Fc = ferrocenyl.
Table 2. Results of Cyclic Voltammetry
and recrystallization. 2-Isopropylaniline also undergoes the
condensation with 1,1ꢀ-bis(hydroxymethyl)ferrocene to afford
4 in 32% yield, indicating that the presence of the bulky sub-
stituent at ortho position does not block the C–N bond forma-
tion. The OH group of 1 was substituted with iodine atom by
the reaction of 1 with NaI in the presence of P2O5 and
Me3SiOSiMe3 to give 7, which has a 6-iodohexyl substituent at
the nitrogen, as shown in Eq. 2.13,14
Compound
Electrochemical Potential/V (vs Ag+/Ag)a)
E1/2 (I− ↔ I2)b) E1/2 (Fe(Ⅱ) ↔ Fe(Ⅲ)) Eox (amine)b)
1
2
3
4
5
−0.01 (0.10)
−0.01 (0.15)
+0.04 (0.09)
+0.04 (0.12)
+0.04 (0.06)
+0.44
+0.42
+0.41
c)
—
c)
—
9-I−
−0.11
−0.15
+0.42 (0.06)
+0.42 (0.07)
+0.37 (0.09)
+0.39 (0.10)
−
9-BF4
12-I−
−
12-BF4
(2)
The ferrocenophanes 1–7 were characterized by means of
NMR spectroscopy and elemental analyses. For example, the
1H NMR spectrum of 1 contains an AB doublet at δ 4.08 and
4.07 due to the cyclopentadienyl hydrogens and a singlet of the
CpCH2 hydrogens at δ 2.89. The OH hydrogen signal is ob-
served at δ 1.57. The 13C{1H} NMR spectrum exhibits the
OCH2, NCH2(6-hydroxyhexyl), and NCH2Cp carbon signals at
δ 63.0, 57.6 and 52.2, respectively. The peak positions are
close to the corresponding hydrogen signals of analogous N-
alkyl-2-aza-[3]-(1,1ꢀ)-ferrocenophanes. Ferrocenophanes 2–5
also give reasonable NMR spectra for the proposed structure.
The 1H and 13C{1H} NMR spectra of 6 indicate the presence of
1,1ꢀ-disubstituted ferrocenylene and 1-substituted ferrocenyl
groups. The two CH2 hydrogen signals are observed at δ 3.84
and 2.85 in a 1:2 peak area ratio. These spectroscopic data as
well as analytical results confirm the N-ferrocenomethyl-2-
aza-[3]-(1,1ꢀ)-ferrocenophane structure.
a) ∆E (= Epc − Epa, V) is shown in parentheses.
b) Irreversible oxidation. c) Not observed clearly.
(1,1ꢀ)-ferrocenophane shows the corresponding oxidation
wave at a lower potential (E1/2 = 0.44 V). The reaction was as-
signed to the electrochemical oxidation of the NCH2 group of
the ligand accompanied by deprotonation as shown in Scheme
2 (i). The initially formed ferrocenium (A) is in equilibrium
with (Aꢀ) having Fe(Ⅱ) center and a cation radical at the nitro-
gen atom via rapid and reversible electron transfer between Fe
and N atoms.15 Further oxidation of the ligand accompanied
by proton elimination leads to the product having an iminium
structure (B). The latter reaction lacks in reversibility, due to
low affinity of the iminium group and H+ under the electro-
chemical reduction conditions. The fact that the oxidation po-
tential of 1–3 with N-alkyl substituents is lower than that of the
N-aryl derivatives can be attributed to the basicity of the alkyl
amines being higher than that of the aryl amines. The electro-
chemical behavior of N-aryl-2-aza-[3]-(1,1ꢀ)-ferrocenophanes,
N-(4-t-butylphenyl)-2-aza-[3]-(1,1ꢀ)-ferrocenophane and N-(4-
hydroxyphenyl)-2-aza-[3]-(1,1ꢀ)-ferrocenophane (8),12 is com-
pared in Figs. 1b and c. Both compounds exhibit the redox be-
N-Alkyl-2-aza-[3]-(1,1ꢀ)-ferrocenophanes 1–3 undergo two
electrochemical oxidation reactions at different potentials, as
described below. Figure 1a depicts the cyclic voltammogram
of 1, which shows two oxidation waves, at 0.06 V and 0.44 V
(Ag+/Ag). The former electrochemical reaction is reversible,
since a scanning up to 0.20 V leads to reversible oxidation and
reduction waves at Epc − Epa = 98 mV. Similar two step redox
was obtained for 2 and 3, as summarized in Table 2. Cyclic
voltammograms of 4 and 5 show electrochemical response of
ferrocene-ferrocenium redox only. The electrochemical mea-
surement of 6 was not feasible, partly due to its low solubility
in polar organic solvents.
tween ferrocene and ferrocenium at similar positions (E1/2
=
0.04 and −0.02 V, respectively). The former compound shows
a second oxidation at Eox = 0.75 V with low reversibility,
whereas 8 undergoes reversible electrochemical oxidation and
reduction at a lower potential (E1/2 = +0.44 V). Scheme 2 (ii)
depicts the mechanism which accounts for the unique electro-
chemical behavior of 8. The initial oxidation of 8 produces a
ferrocenium (C) which is in equilibrium with the ferro-
cenophane-containing cation radical at the nitrogen atom (Cꢀ)
similarly to Scheme 2 (i). Further oxidation and deprotonation
Our previous study12 revealed that the N-aryl-2-aza-[3]-
(1,1ꢀ)-ferrocenophanes exhibit an irreversible electrochemical
oxidation at Eox = 0.68–0.75 V and that N-hexyl-2-aza-[3]-

T. Sakano et al.
Bull. Chem. Soc. Jpn., 74, No. 11 (2001) 2061
Scheme 2.
of the OH group affords the species with a iminium quinone
structure in the ligand (D). The stability of (D) is much higher
than that of (B); this is probably the primary reason for the ox-
idation potential of 8 being lower than those of 7 and the other
N-aryl-2-aza-[e]-ferrocenophanes. Since protonation of the
oxygen of D takes place to regenerate the ferrocenium (C) eas-
ily under the electrochemical reduction conditions, the total
electrochemical process shown in Scheme 2 (ii) occurs with
high reversibility.
subsequent addition of NH4PF6 to the reaction mixture (Eq. 5).
(3)
Figure 2 depicts absorption spectra obtained during the elec-
trochemical oxidation of 8 using a flow electrolysis cell.16 Be-
fore oxidation, the spectrum (a) contains an absorption due to
8 (247 nm) exclusively. Oxidation up to 0.0 V leads to a de-
crease in the peak at UV region and to concomitant growth of
new peaks at 375 and 535 nm. They can be assigned to the ni-
trogen radical cation of (Cꢀ) in Scheme 2 (ii) and ferrocenium
cation (C), respectively, based on comparison of the spectrum
with those of oxidized polyaniline and ferrocenium.17 At high-
er potentials (above 0.30 V), a new absorption band at nearly
800 nm is observed, which is ascribed to further oxidation of
the N-substituent and deprotonation of the OH group, afford-
ing the species with a quinone-imine structure (D). The reac-
tion pathway shown in Scheme 2 is consistent with the above
electrochemical and spectroscopic measurements, although the
intermediates in the Scheme were not fully identified.
(4)
(5)
As reported previously, N-hexyl-2-aza-[3]-(1,1ꢀ)-ferro-
cenophane reacts with MeI to produce the quaternary ammoni-
um derivative 9-I− (Eq. 3).12 The reaction of N-alkyl-2-aza-
[3]-(1,1ꢀ)-ferrocenophanes (1–3) with MeI also give the corre-
sponding N-methylated cationic compounds, 10-I−, 11-I−, and
12-I−, respectively, as shown in Eq. 3. The iodo counter anion
is easily replaced with BF4− by addition of AgBF4 to a solution
of the quaternary group containing ferrocenophanes (Eq. 4).
The structures of these complexes were confirmed by NMR
spectroscopy and X-ray crystallography. Figure 3 displays
−
structures of the cationic part of 10-I−, 11-I−, and 12-PF6
.
These cationic ferrocenophanes have the quaternary nitrogens
with an almost tetrahedral structure. The N–C bonds in aver-
age are longer than those of neutral azaferrocenophanes due to
the presence of positive charge, as summarized in Table 3.
Separation of the iodo anion from the cationic part of the ferro-
cenophanes is sufficiently large in the solid state. Figure 4
−
PF6 salt of the cationic N-methylated ferrocenophane 12-
PF6− was obtained from a one-pot reaction of 3 with MeI and

2062 Bull. Chem. Soc. Jpn., 74, No. 11 (2001)
N-Alkyl-2-aza-[3]-ferrocenophanes
−
Fig. 3. Molecular structures of 10-I−, 11-I−, and 12-PF6
determined by X-ray crystallography. Counter anions and
hydrogen atoms are omitted for simplicity. As for 10-I−,
one of the two crystallographically independent molecules
is shown.
Fig. 1. Cyclic voltammograms of (a) 1, (b) N-(4-t-butylphen-
yl)-2-aza-[3]-(1,1ꢀ)-ferrocenophane (c) N-(4-hydroxyphen-
yl)-2-aza-[3]-(1,1ꢀ)-ferrocenophane in MeCN solutions
containing Et4NBF4 (0.10 M) (scan rate = 100 mV s−1).
The E1/2 values of (b) (E1/2 = +0.04 and +0.45 V) and (c)
(E1/2 = +0.04 and +0.44 V) shown in our previous
report12 were not correct, but are actually (b) E1/2 = +0.06
Table 3. Selected Bond Distances and Angles
−
10-I−a)
11-I−
12-PF6
N1–C11
N1–C12
N1–C13
N1–C14
1.519(9) 1.546(9)
1.57(1)
1.54(1)
1.50(1)
1.55(1)
1.53(1)
1.56(1)
1.52(1)
1.52(1)
1.55(1)
1.50(1)
1.53(1)
1.516(9)
1.49(1)
1.52(1)
(∆E = 0.07 V) and +0.67 V (∆E = 0.06 V) and (c) E1/2
=
−0.02 (∆E = 0.07 V) and +0.41V (∆E = 0.08 V). These
results were not discussed in detail in our previous paper.
N1–C11–C1 118.2(8) 118.6(7) 116.5(9) 119.3(8)
N1–C12–C6 119.3(8) 118.7(7) 118(1) 119.4(8)
a) The parameters in the right column of 10-I− are those
of the crystallographically independent molecule.
Fig. 2. Absorption spectra of 1.0 × 10−4 M of N-(4-hydroxy-
phenyl)-2-aza-[3]-ferrocenophane (8) in MeCN solutions
containing Et4NBF4 (0.10 M) at (a) −0.40 V, (b) +0.00 V,
(c) +0.30 V, and (d) +0.40 V (vs Ag+/Ag).
Fig. 4. 13C{1H} NMR spectrum of 12-I− in CDCl3.

T. Sakano et al.
Bull. Chem. Soc. Jpn., 74, No. 11 (2001) 2063
shows the 13C{1H} NMR spectrum of 12-I− in CDCl3. Peaks
of the NCH2 carbon (δ 65.8) and Cp-CH2 carbon (δ 57.9) ap-
pear at significantly lower positions than the corresponding
carbon peaks of non-methylated ferrocenophane 3 (δ 57.4 and
52.3, respectively) owing to the existence of the positive
charge at the nitrogen. The 1H NMR spectra of 12-I− and 12-
BF4− are similar but not exactly identical to each other, which
may suggest the presence of weak interaction between the cat-
ionic ferrocenophane and the counter ion in solution. Storage
of the solution of 12-I− for several days caused color change of
the solution to red brown, probably due to formation of I2 in
solution, although the ferrocene-containing product was not
than the potentials of 3 (E1/2 = +0.03 V) can be rationalized
by the existence of positive charge at the nitrogen atom close
to the Fe center, which prevents facile electrochemical oxida-
tion around the nitrogen atom. Such smaller electrochemical
peaks of 12-I− at +0.30 V may be assigned to a minor fer-
rocene-containing product due to the oxidation of the iodo
counter ion because the cyclic voltammogram of 12-BF4− does
not show such redox waves.
N-alkyl- and N-aryl-2-aza-[3]-(1,1ꢀ)-ferrocenophanes pre-
pared in our previous and present studies exhibit several kinds
of unique chemical and electrochemical behavior. Since we
also succeeded in immobilization of the ferrocenophanes in
polymer matrices,18 application of these for electrodes or catal-
ysis can be expected.
−
characterized. 12-BF4 shows much higher stability than 12-
I− in solution.
Figure 5 depicts cyclic voltammograms of 12-I− and 12-
Experimental Section
−
BF4 in addition to the non-N-methylated neutral ferro-
cenophane 3. 12-I− exhibits the irreversible oxidation of I− to
I2 at E1/2 = −0.15 V (vs Ag+/Ag, Eox = −0.04 V) and two ad-
ditional reversible redoxes leading to two pairs of oxidation
and reduction peaks. The large peaks at E1/2 = +0.37 V are in
General Consideration, Materials, and Measurement. All
the manipulations of [RuCl2(PPh3)3] were carried out under nitro-
gen or argon using standard Schlenk techniques. The NMR spec-
tra (1H and 13C{1H}) were recorded on a JEOL EX-400 spectrom-
eter at 25 °C unless otherwise stated. Elemental analyses were
carried out by aYanaco MT-5 CHN autocorder. Cyclic voltamme-
try was measured in MeCN solution containing 0.10 M Et4NBF4
with ALS Electrochemical Analyzer Model-600A. The Ag+/Ag
reference was used as the reference. Spectroelectrochemical mea-
surements were carried out by using a combination of a flow
through electrolysis cell, ALS Electrochemical Analyzer Model-
600A and EYELA peristaltic pump SMP-11, and Shimadzu
UV1600 spectrometer. Details of apparatus were reported previ-
ously.16 [RuCl2(PPh3)3] and 1,1ꢀ-bis(hydroxymethyl)ferrocene
were prepared according to literature methods.19,20 Acetonitrile
and 1-methyl-2-pyrrolidinone (NMP) were dried over CaH2, dis-
tilled, and stored under nitrogen or argon. Et4NBF4 for the elec-
trochemical measurement was recrystallized from methanol be-
fore use.
−
positions close to those of 12-BF4 (0.39 V), indicating that
the electrochemical reaction corresponds to oxidation and re-
duction of the Fe center of cationic ferrocenophane 12-I−.
Why the oxidation potentials of 12-I− and 12-BF4− are higher
Preparation of 1–6. To an NMP (3 cm3) solution of
[RuCl2(PPh3)3] (67 mg, 0.070 mmol) was added 6-aminohexanol
(234 mg, 2.0 mmol) and then 1,1ꢀ-bis(hydroxymethyl)ferrocene
(492 mg, 2.0 mmol) at room temperature. The mixture was heated
at 180 °C for 24 h. After the solution was evaporated under vacu-
um, the remaining residue was dissolved in ethyl acetate to re-
move the insoluble fraction by filtration. The soluble material was
purified by column chromatography (silica gel, hexane:ethyl ace-
tate = 2:1) and was recrystallized from a chloroform–methanol
mixture to afford 1 as a yellow solid (124 mg, 19%). 1H NMR
(CDCl3) δ 4.08, 4.07 (d, 8H, Cp, J = 2 Hz), 3.68 (t, 2H, CH2OH),
2.89 (s, 4H, Cp-CH2-N), 2.69 (t, 2H, NCH2, J = 7 Hz), 1.62 (m,
4H, NCH2 and CH2OH), 1.57 (s, 1H, OH), 1.44 (q, 4H,
(CH2)2CH2OH). 13C{1H} NMR (100 MHz, in CDCl3 at 25 °C) δ
83.2 (Cp-CH2-N), 69.8, 69.1 (Cp), 63.0 (CH2OH), 57.6 (NCH2),
52.2 (Cp-CH2-N), 32.8, 27.6, 27.2, 25.6 (CH2).
Other N-substituted-2-aza-[3]-(1,1ꢀ)-ferrocenophanes 2–6 were
prepared analogously and their data are shown below. NMR data
of 2. Abbreviation of hydrogens is shown in Chart 1. 1H NMR
Fig. 5. Cyclic voltammograms of (a) 3, (b) 12-I−, and (c) 12-
−
BF4 in MeCN solutions containing Et4NBF4 (0.10 M)
(scan rate = 100 mV s−1).
Chart 1.

2064 Bull. Chem. Soc. Jpn., 74, No. 11 (2001)
N-Alkyl-2-aza-[3]-ferrocenophanes
(CDCl3) δ 4.08, 4.04 (d, 8H, Cp, J = 2 Hz), 3.02 (s, 4H, Cp-CH2-
N), 2.72 (tt, 1H, NCHa, J = 3, 12 Hz), 1.90 (d, 2H, Hb, J = 12
Hz), 1.83 (d, 2H, Hc, J = 12 Hz), 1.65 (m, 1H, Hd), 1.36 (m, 2H,
He), 1.27 (m, 2H, Hf), 1.14 (tt, 1H, Hg, J = 3, 12 Hz). 13C{1H}
NMR (100 MHz, in CDCl3 at 25 °C) δ 84.4 (Cp-CH2-N), 69.8,
68.8 (Cp), 64.9 (NCH), 48.8 (Cp-CH2-N), 29.7 (NCHCH2) 26.5,
26.4 (NCHCH2CH2CH2).
7 Hz), 3.00 (s, 4H, Cp-CH2-N), 2.77 (t, 2H, NCH2, J = 7 Hz),
1.87 (quintet, 2H, ICH2CH2), 1.67 (quintet, 2H, NCH2CH2), 1.46
(m, 4H, CH2). 13C{1H} NMR (100 MHz in CDCl3 at 25 °C) δ
82.5 (Cp-CH2-N), 70.0, 69.4 (Cp), 57.6 (NCH2), 52.1 (Cp-CH2-
N), 33.5, 30.3, 27.0, 26.3 (CH2(CH2)4CH2), 7.01 (CH2I).
Preparation of 10-I−–12-I−. To the MeCN (5 cm3) suspen-
sion of 1 (63 mg , 0.19 mmol) was added MeI (81 mg, 0.57 mmol)
at room temperature. Compound 1 was instantly dissolved on stir-
ring. After 24 h, a crystalline product was separated from the so-
lution and was collected by filtration. The resulting orange solid
was recrystallized from CHCl3/Et2O (65 mg, 72%) to give 10-I−.
Anal. Calcd for C19H28FeINO: C, 48.64; H, 6.02; N, 2.99; I,
27.05%. Found: C, 48.68; H, 5.95; N, 2.58; I, 26.50%. 1H NMR
(CDCl3) δ 4.56, 4.50, and 4.47 (m, 4H, CpCH2N), 4.34 and 4.29
(8H, Cp ring), 3.88 (br, 2H, NCH2CH2), 3.68 (t, 2H, CH2OH),
3.56 (s, 3H, Me), 1.96 (br, 2H, NCH2CH2), 1.61 (quintet, 2H,
CH2CH2OH), 1.60 (s, 1H, OH), 1.56 (br, 4H, CH2(CH2)2CH2OH).
11-I− and 12-I− were obtained analogously from 2 and 3, re-
spectively. Analytical data of 11-I−. Anal. Calcd for C23H28FeIN:
C, 50.58; H, 5.81; N, 3.10%. Found: C, 50.28; H, 5.79; N, 2.66%.
NMR data of 12-I−. 1H NMR (CDCl3) δ 7.33–7.19 (Ph), 4.50,
4.53, 4.49 (m, 4H, Cp-CH2N), 4.30–4.10 (br, 8H, Cp), 3.81 (m,
2H, NCH2), 3.52 (s, 3H, Me), 2.76 (t, 2H, PhCH2), 2.00–1.75 (m,
4H, NCH2CH2 and PhCH2CH2). 13C{1H} NMR (100 MHz, in
CDCl3 at 25 °C) δ 140.6 (ipso, C6H5), 128.7, 128.6, 126.3 (ortho,
meta, para, C6H5), 73.1 (Cp-CH2-N), 72.8 (Me), 72.3, 71.8 (Cp),
65.8 (NCH2CH2), 57.9 (CpCH2-N), 35.0, 27.9, 22.5 (CH2).
NMR data of 11-I− and analytical data of 12-I− were not ob-
tained.
NMR data of 3. 1H NMR (CDCl3) δ 7.30 (t, 2H, meta, J = 7
Hz), 7.21 (d, 2H, ortho, J = 7 Hz), 7.19 (t, 1H, para, J = 7 Hz),
4.08, 4.07 (d, 8H, Cp, J = 2 Hz), 2.88 (s, 4H, Cp-CH2N), 2.71 (t,
2H, NCH, J = 8 Hz), 2.69 (t, 2H, PhCH2, J = 8 Hz), 1.74 (quin-
tet, 2H, NCH2CH2, J = 7 Hz), 1.67 (quintet, 2H, PhCH2CH2, J =
8 Hz). 13C{1H} NMR (100 MHz, in CDCl3 at 25 °C) δ 142.7 (ip-
so, C6H5), 128.4, 128.3, 125.7 (ortho, meta, para, C6H5), 83.8
(Cp-CH2-N), 69.8, 69.0 (Cp), 57.4 (NCH2CH2), 52.3 (CpCH2-N),
35.8 (PhCH2), 29.3 (NCH2CH2), 27.3 (PhCHCH2).
NMR data of 4. 1H NMR (CDCl3) δ 7.15–7.35 (m, 4H, Ph),
4.24, 4.15 (d, 8H, Cp, J = 3 Hz), 3.81 (m, CH3CH-), 3.34 (s, 4H,
Cp-CH2-), 1,28 (d, 6H, CH3). 13C{1H} NMR (100 MHz, in CDCl3
at 25 °C) δ 145.0 (ipso, NC6H5), 126.3, 126.3, 125.1, 122.4 (ortho,
meta, para, NC6H5), 83.5 (Cp-CH2-N), 70.0, 69.5 (Cp), 53.5
(CpCH2-N), 26.6 (CH3CH), 23.6 (CH3CH).
NMR data of 5. 1H NMR (CDCl3) δ 7.61, 7.56 (d, 4H, Ph, J =
9 Hz), 4.12, 4.09 (d, 8H, Cp, J = 2 Hz), 3.89 (s, 2H, CH2-N), 2.90
(s, 4H, Cp-CH2-N). 13C{1H} NMR (100 MHz, in CDCl3 at 25 °C)
δ 144.1 (para, C6H4CF3), 129.2 (ipso, C6H4CF3, 2J(C–F) = 29 Hz),
3
129.0 (meta, C6H4CF3), 125.2 (ortho, C6H4CH3, J(C–F) = 4 Hz),
1
124.3 (CF3, J(C–F) = 271 Hz), 83.1 (Cp-CH2-), 69.8, 69.2 (Cp),
61.3 (C6H4-CH2-N), 52.3 (Cp-CH2-N).
NMR data of 6. 1H NMR (CDCl3) δ 4.22 (t, 2H, Ha, J = 3 Hz),
4.15 (m, 6H, Hb and Hf), 4.05 (m, 9H, Hc and Hg), 3.84 (s, 2H,
Hd), 2.85 (s, 4H, Hc) (Chart 2). 13C{1H} NMR (100 MHz, in
CDCl3 at 25 °C) δ 83.2 (Cp-CH2-N), 83.2 (Cp-CH2-N), 70.2, 69.5,
69.1, 68.5, 67.9 (Cp), 57.9 (Cp-CH2-N), 51.1 (crosslinked Cp-
CH2-N).
Anion Exchange of 9-I− and 12-I− with AgBF4. To an ace-
tone (5 cm3) suspension of 12-I− (95 mg, 0.19 mmol) was added
AgBF4 (37 mg, 0.19 mmol) at room temperature, then readily a
white solid was precipitated. The reaction mixture was filtered to
remove the AgI and evaporated at reduced pressure. The obtained
crude products were recrystallized from CHCl3/ether to lead 12-
BF4− as yellow crystals (67 mg, 76%). 1H NMR (CDCl3) δ 7.32–
7.19 (Ph), 4.30, 3.90 (br, 8H, Cp), 4.39, 4.08 (s, 4H, Cp-CH2N),
3.60 (m, 2H, NCH2), 3.32 (s, 3H, Me), 2.75 (t, 2H, PhCH2), 2.00–
1.75 (m, 4H, NCH2CH2 and PhCH2CH2).
N-(6-Iodohexyl)-2-aza-[3]-(1,1ꢀ)-ferrocenophanes (7). Pre-
paration was carried out according to the reported procedure with
slight modification as follows.13,14 A mixture of phosphorus pen-
toxide (1.31 g, 9.2 mmol), hexamethyldisiloxane (1.49g, 9.2
mmol), and dry benzene (15 cm3) was refluxed for 30 min until
the mixture became a clear solution. The solvent was removed
and toluene (5 cm3), sodium iodide (138 mg, 0.92 mmol), 1 (260
mg, 0.80 mmol) were added in this order at room temperature.
The reaction mixture was heated at 50 °C for 24 h with stirring. A
saturated aqueous sodium bicarbonate solution containing sodium
thiosulfate was added to quench the reaction. The organic prod-
ucts were extracted with ether repeatedly. The combined extracts
were washed with brine and the solvent was evaporated. The
crude product was purified by column chromatography (silica gel,
CHCl3:MeOH = 95.5) to 6 as a yellow solid (215 mg, 61%).
Anal. Calcd for C18H24FeNI: C, 49.46; H, 5.53; N, 3.20; I,
29.03%. Found: C, 48.68; H, 5.39; N, 2.97; I, 28.98%. 1H NMR
(CDCl3) δ 4.16, 4.09 (d, 8H, Cp, J = 2 Hz), 3.22 (t, 2H, CH2I, J =
Anion exchange of 9-I− was carried out analogously.
−
Preparation of 12-PF6
.
MeCN (5 cm3) suspension of 3 (63
mg, 0.18 mmol) was added MeI (77 mg, 0.54 mmol) at room tem-
perature. Compound 3 was instantly dissolved on stirring. After
24 h, a crystalline product was separated from the solution and
was collected by filtration. The obtained crystals were dissolved
in MeCN and NH4PF6 (32 mg, 0.20 mmol) was added. The reac-
tion mixture was stirred for 1 h, then H2O was added to precipitate
the product. Solids were filtered and washed with H2O repeatedly.
The obtained crude products were recrystallized from CHCl3/ether
to give 12-PF6− as orange crystals (76 mg, 82%). Anal. Calcd for
C23H24F6FeNP: C, 53.20; H, 5.43; N, 2.70%. Found: C, 53.53; H,
5.71; N, 2.62%.
Crystal Structure Determination. Crystals of 10-I−, 11-I−,
and 12-PF6− suitable for X-ray diffraction study were obtained by
recrystallization from CHCl3-Et2O and mounted in glass capillary
tubes under argon. Intensities were collected for Lorentz and po-
larization effects on a Rigaku AFC-5R automated four-cycle dif-
fractometer by using Mo-Kα radiation (λ = 0.71069 Å) and ω-2θ
scan method, and an empirical absorption correction (Ψ scan) was
applied. Calculations were carried out using a program package
TEXSAN for Windows. Atomic scattering factors were obtained
from the literature.21 A full matrix least-squares refinement was
Chart 2.

T. Sakano et al.
Bull. Chem. Soc. Jpn., 74, No. 11 (2001) 2065
−
Table 4. Crystallographic Data of 10-I−, 11-I−, and 12-PF6
−
10-I−
11-I−
12-PF6
Formula
M
C19H28FeNOI
469.19
C19H26FeNI
451.17
C23H28FeNPF6
519.29
Crystal Size
Crystal system
Space group
a/Å
0.5 × 0.6 × 0.8
monoclinic
P21/c (No. 14)
12.507(5)
20.669(7)
15.001(7)
93.30(2)
3871(2)
0.4 × 0.4 × 0.6
monoclinic
P21/c (No. 14)
7.169(3)
17.504(3)
14.965(4)
96.04(3)
1867.3(8)
4
0.5 × 0.9 × 1.0
monoclinic
Cc (No. 9)
10.534(5)
16.805(5)
13.466(6)
107.40(3)
2275(2)
b/Å
c/Å
β/deg
V/Å3
Z
4
4
µ(MoKα)/ mm−1
Unique reflections
Used reflections
(I > 3.00σ(I))
R (F0)
2.378
7694
3197
2.458
4445
2182
0.792
2694
1890
0.047
0.043
0.068
0.048
0.066
0.056
Rw (F0)
used for non-hydrogen atoms with anisotropic thermal parame-
ters. Hydrogen atoms were located by assuming the ideal geome-
try and these locations were included in the structure calculation
without further refinement of the parameters. Crystallographic
data and details of refinement are summarized in Table 4. All the
data of the crystallographic study including Fo-Fc tables are de-
posited as Document No. 74059 at the Office of the Editor of Bull.
Chem. Soc. Jpn. Crystallographic data are deposited also at the
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK and copies can
be obtained on request, free of charge, by quoting the publication
citation and the deposition numbers 169227–169229.
Lett., 23, 229 (1982).
8
Y. Watanabe, Y. Tsuji, H. Ige, Y. Ohsugi, and T. Ohta, J.
Org. Chem., 49, 3359 (1984).
9
Y. Tsuji, K.-T. Huh, Y. Ohsugi, and Y. Watanabe, J. Org.
Chem., 50, 1365 (1985).
10 Y. Tsuji, K.-T. Huh, Y. Yokoyama, and Y. Watanabe, J.
Chem. Soc., Chem. Commun., 1986, 1575.
11 Y. Tsuji, Y. Yokoyama, K.-T. Huh, and Y. Watanabe, Bull.
Chem. Soc. Jpn., 60, 3456 (1987).
12 T. Sakano, H. Ishii, I. Yamaguchi, K. Osakada, and T.
Yamamoto, Inorg. Chim. Acta, 296, 176 (1999).
13 T. Iwamoto, T. Matsumoto, T. Kusumoto, and M.
Yokoyama, Synthesis, 1983, 460.
14 T. Iwamoto, H. Yokoyama, and M. Yokoyama, Tetrahedron
Lett., 22, 1803 (1981).
15 H. Plenio, J. Yang, R. Diodone, and J. Heinze, Inorg.
Chem., 33, 4098 (1994).
This work was financially supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology.
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