Solvent-free synthesis of ferrocenylimines

Article abstract of DOI:10.1016/j.jorganchem.2004.02.008

The mixing of equimolar quantities of ferrocenylaldehydes and aromatic amines in a solvent-free environment provided excellent yields of ferrocenylimines. After mixing the aldehydes and amines, a melt formed which eventually solidified to the product. An analytically pure sample of the product was obtained by cold recrystallization. 2004 Elsevier Science B.V. All rights reserved.

Full text of DOI:10.1016/j.jorganchem.2004.02.008

Journal of Organometallic Chemistry 689 (2004) 1617–1622
www.elsevier.com/locate/jorganchem
Solvent-free synthesis of ferrocenylimines
*
Christopher Imrie , Vincent O. Nyamori, Thomas I.A. Gerber
Department of Chemistry, University of Port Elizabeth, P.O. Box 1600, Port Elizabeth 6000, South Africa
Received 17 October 2003; accepted 6 February 2004
Abstract
The mixing of equimolar quantities of ferrocenylaldehydes and aromatic amines in a solvent-free environment provided excellent
yields of ferrocenylimines. After mixing the aldehydes and amines, a melt formed which eventually solidified to the product. An
analytically pure sample of the product was obtained by cold recrystallization.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Ferrocenylimines; Green chemistry; Solvent-free synthesis
1. Introduction
by the solvent-free mixing of ferrocenylaldehydes and
aromatic amines.
There has recently been an upsurge of interest in
performing chemical transformations in a solvent-free
environment. For example, McCluskey et al. [1] have
described solvent-free Knoevenagel condensation reac-
tions (Scheme 1). In comparison to methods employing
molecular solvents, the solvent-free approach proceeded
more cleanly and provided higher yields. Further ex-
amples of the solvent-free approach to organic trans-
formations can be found in a recent feature article [2]
and a monologue on the subject has recently appeared
[3].
One of our current research objectives is to introduce
the Green Chemistry Principles [4] into the synthesis of
simple ferrocenyl derivatives. In otherwords, our aim is
to synthesize ferrocenes using reactions that have a high
atom economy, that are conducted under ambient con-
ditions and that use non-toxic recyclable solvents. So
far, we have reported on the synthesis of ferrocenoyl
esters in [bmim][BF4] and [bmim][PF6] [5]. A major
concern in using ionic liquids such as imidazolium salts
as reaction solvent rests with their possible toxicity and
persistence in the environment [6]. In this paper, we
describe a highly efficient synthesis of ferrocenylimines
2. Results and discussion
The synthesis of ferrocenylimines by reaction of fer-
rocenylaldehydes with aromatic amines has been re-
ported by several research groups [7]. The imines are
potentially useful ligands for metal complexation and
many of the ferrocenylimines have been investigated for
non-linear optical properties [8]. In the majority of
cases, the ferrocenylimines were prepared by heating a
solution of the ferrocenylaldehyde and aromatic amine
in solvents such as anhydrous methanol or ethanol. Our
research group has also previously utilized this method
[9]. One of the problems associated with it is that ther-
mally sensitive ferrocenylimines suffer a degree of de-
composition during the heating process. To avoid this
problem and to fit in more closely with the principles of
green chemistry [4], the reactions have been conducted
in a solvent-free environment.
The reactions conducted with ferrocenylaldehydes are
shown in Scheme 2. 4-Formylphenylferrocene 1 and 40-
ferrocenyl-biphenyl-4-carbaldehyde 2 were prepared by
a modified Suzuki cross-coupling reaction. 4-(4-Ferr-
ocenyl-phenoxy)-benzaldehyde 3 was prepared by the
copper(II) acetate coupling of 4-ferrocenylphenol and
* Corresponding author. Fax: +27-41-504-2573.
E-mail address: chacci@upe.ac.za (C. Imrie).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.02.008

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C. Imrie et al. / Journal of Organometallic Chemistry 689 (2004) 1617–1622
Scheme 1. Solvent-free Knoevenagel reactions.
X
N
O
X
Ar
C
Grind
No solvent
C
Ar
+ H2N
H
H
Ar
4
(Ar= Fc)
5
6
7
(Ar= Fc-Ph)
Fe
Fe
(Fc)
(Ar= Fc-Ph-Ph)
(Ar= Fc-Ph-O-Ph)
(Fc-Ph)
1
2
(Fc-Ph-Ph)
Fe
Fe
O
(Fc-Ph-O-Ph)
3
Scheme 2. Reactions of ferrocenylaldehydes with aromatic amines.
Table 1
Yields of ferrocenylimines from the solvent-free reaction of ferro-
cenylaldehydes and aromatic amines
4-formylbenzeneboronic acid [9]. The mixing of an
equimolar quantity of the ferrocenylaldehyde and aro-
matic amine provided in most cases a melt after a few
minutes. An example of a reaction is that between fer-
rocenecarboxaldehyde and 4-tetradecyloxyaniline. On
mixing the sample of 4-tetradecyloxyaniline with ferro-
cenecarboxaldehyde, a melt was obtained and this
gradually solidified at room temperature under vacuum
to give the imine product in high yield (entry 5, Table 1).
The solidified melt was initially analyzed by IR
spectroscopy using a KBr pellet in order to substanti-
ate that the reaction was more or less completed under
solvent-free conditions. An example of an IR spectrum
is provided in Fig. 1 for the solvent-free reaction of 4-
formylphenylferrocene and 4-tetradecyloxyaniline. The
strong band associated with 4-formylphenylferrocene
(CO) which usually resides at approximately 1700 cmꢀ1
is absent and is replaced by a strong band at 1631
cmꢀ1 (Fig. 1) which is the normal region for an imine
bond (C@N). The solidified melt was finally crystal-
lized from cold anhydrous methanol and this provided
Entry
Ferrocenylaldehyde
Aromatic amine
Yield of
ferroce-
nyliminea
(%)
H2N
X
X
1
2
FcCHO
FcCHO
4-Cl
4-CH3
4-NO2
94
97
92
93
94
95
96
92
87
91
90
3
FcCHO
FcCHO
4
4-OC8H17
4-OC14H29
4-Fc
5
FcCHO
FcCHO
6
7
FcPhCHO
FcPhCHO
FcPhPhCHO
FcPhPhCHO
FcPhOPhCHO
4-OC14H29
4-Fc
8
9
4-OC8H17
4-OC14H29
4-OC14H29
10
11
a Yields are based on the starting materials and are isolated ones.
1
to the variation in the aldehyde and the nature of the
substituent in the aniline are provided in Table 1 and
are generally very good. In some instances, notably
a product with a high degree of purity as judged by H,
13C NMR, high resolution mass spectroscopy and mi-
croanalysis. The isolated yields of the imines according

C. Imrie et al. / Journal of Organometallic Chemistry 689 (2004) 1617–1622
1619
obtain a good conversion. Analysis of the reaction
between ferrocenecarboxaldehyde and 4-nitroaniline
was carried out by DSC and the results are shown in
Fig. 2. First of all, the starting materials and the
product were analyzed individually. Ferrocenecarbox-
aldehyde (Fig. 2(a)) shows a phase transition at 48 °C
representing the formation of a so-called plastic crystal
phase [10] and this runs to its melting point at 121 °C.
The 4-tetradecyloxyaniline and imine product exhibited
sharp melting points (57° and 78°, respectively). The
DSC analysis of the solvent-free reaction is shown in
Fig. 2(b) and it indicates that the reaction began at the
point where ferrocenecarboxaldehyde entered the
plastic crystal phase. This suggests that the reaction
could be promoted by the phase change and this
warrants future investigations.
The melting behaviors of the imine products are in
accordance with the guidelines provided by Imrie and
Loubser [11]. Compounds containing one ferrocenyl
group plus one phenyl ring have sharp melting points;
those with one ferrocenyl group plus two phenyl rings
show some crystal–crystal phase transitions and finally
those with one ferrocenyl group and three phenyl rings
exhibit liquid crystal behavior.
Fig. 1. IR spectrum of 4-tetradecyloxy-N-[4-(4-ferrocenyl)benzylid-
ene]-aniline.
where the aromatic amine contained an electron-with-
drawing group (Table 1, entry 3) or where the aldehyde
was less reactive (Table 1, entry 11), gentle heating
(50 °C) of the solid reaction mixture was required to
5
0
-5
-10
-15
-20
-25
20
40
60
80
100
120
140
160
180
200
220
240
260
(a)
Temperature (°C)
4
2
0
-2
-4
-6
-8
-10
-12
-14
-16
25
50
75
100
Temperature (°C)
125
150
175
200
(b)
Fig. 2. DSC analysis of (a) ferrocenecarboxaldehyde and (b) the reaction between ferrocenecarboxaldehyde and 4-tetradecyloxyaniline.

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C. Imrie et al. / Journal of Organometallic Chemistry 689 (2004) 1617–1622
3. Conclusion
4.2. General procedure for the reaction of ferrocenylalde-
hydes and aromatic amines
A simple, convenient and more environmentally
friendly route for the synthesis of ferrocenylimines has
been described. This involved the solvent-free mixing
of substituted anilines and ferrocenylaldehydes. The
yields of ferrocenylimines were very high and purifica-
tion was achieved simply by cold recrystallization from
methanol.
The ferrocenylaldehyde and aniline (equimolar
quantities) were added to a pyrex tube fitted with a
ground glass joint. The two compounds were ground
together using a glass rod at room temperature. In some
cases, a gum formed and in others the mixture turned
into a melt. The pyrex tube was sealed and then placed
on a shaker for approximately 30 min at room temper-
ature. In cases where the starting materials were less
reactive, the pyrex tube was immersed in a constant
temperature water bath at 50 °C. The samples were then
placed under a high vacuum overnight. Initial charac-
terization of the ferrocenylimine was carried out by IR
spectroscopy (KBr disc). This indicated a disappearance
of the carbonyl absorption of the aldehyde and showed
a strong absorption for the imine functional group. The
4. Experimental
4.1. Purification and characterization of the materials
Silica gel 50 was used for column chromatography.
Thin layer preparative chromatography was carried
out on plates using Merck silica gel 60 F254 (1.5 mm)
as adsorbent. M.p.s were recorded on an Electro-
thermal IA 900 series digital m.p. apparatus and are
uncorrected. Infrared spectra were recorded on a
Perkin–Elmer 1600 series Fourier Transform IR
spectrometer as KBr discs or as solutions in chloro-
form. 1H and 13C NMR spectra were recorded on a
Bruker Avance 300 MHz spectrometer as solutions in
CDCl3 using tetramethylsilane (TMS) as internal
standard. Mass spectra were recorded on a micromass
autospec-Tof mass spectrometer at the University of
Potchefstroom in South Africa. Microanalyzes of the
compounds were obtained on a Carlo Erba EA 1108
elemental analyzer. Transition temperatures of the li-
quid crystal molecules were investigated by differential
scanning calorimetry (DSC) utilizing a DSC Q100 cell,
connected to a Universal Analysis thermal analyzer.
Compounds were studied at various scanning rates
(2.5, 5 or 10 °C minꢀ1) for both the heating and
cooling cycles, after being encapsulated in aluminium
pans. An empty aluminium pan served as the refer-
ence. The calorimeter was calibrated with an indium
standard. The textures of the mesophases were studied
with a Nikon Eclipse E 600 optical polarizing micro-
scope equipped with a Linkam heating-freezing stage
linked to a Linkam range TMS 93 precision temper-
ature control at Rhodes University, Grahamstown.
Ferrocenecarboxaldehyde was purchased from the
Strem chemical company (USA) and was used without
further purification. 4-Formylphenylferrocene and 40-
ferrocenyl-biphenyl-4-carbaldehyde were prepared by a
modified Suzuki cross-coupling reaction as described
previously [9]. 4-(4-ferrocenyl-phenoxy)-benzaldehyde
was prepared by the copper(II) acetate-promoted
coupling of 4-ferrocenylphenol and 4-formylbenzen-
eboronic acid [9]. 4-Ferrocenylphenol and 4-ferroce-
nylaniline were prepared by the diazonium salt
method.
1
ferrocenylimines were finally characterized by H, 13C,
mass spectroscopy and microanalysis.
4.3. Preparation of ferrocenylimines derived from ferro-
cenecarboxaldehyde
4.3.1. 4-Chloro-N-(ferrocenylmethylidene)aniline 4 (X ¼
4-Cl)
The general procedure was followed using ferrocen-
ecarboxaldehyde (200 mg, 0.93 mmol) and 4-chloroan-
iline (119 mg, 0.93 mmol). The product was isolated as a
red solid and was recrystallized from cold anhydrous
methanol (283 mg, 94%); m.p. 108–110 °C; IR (KBr
cmꢀ1) 3097, 3015, 2967, 2866, 1619, 1586, 1489, 1464,
1370, 1228, 1186, 1167, 1099, 1040, 1010, 967, 904, 861,
826, 746, 716, 664; 1H NMR (CDCl3) 8.36 (1H, s,
CHN), 7.34 (2H, d, J 7.5, ArH), 7.12 (2H, d, J 7.4,
ArH), 4.83 (2H, t, J 1.8, C5H4), 4.54 ((2H, t, J 1.8,
C5H4), 4.27 (5H, s, C5H5); 13C NMR (CDCl3) 161.31,
151.30, 131.16, 129.61, 122.31, 80.22, 72.14, 70.06,
69.74; m=z 326, 325, 323 (Mþ, 100), 258, 186, 167, 139,
121, 56. Anal. Calc. for C17H14FeNCl: [Mþ],
323.016417. Found: [Mþ], 323.016487.
4.3.2. 4-Methyl-N-(ferrocenylmethylidene)aniline 4 (X ¼
4-CH3)
The general procedure was followed using ferrocene-
carboxaldehyde (200 mg, 0.93 mmol) and 4-methylani-
line (100 mg, 0.93 mmol). The product was isolated as a
red solid and was recrystallized from cold anhydrous
methanol (263 mg, 97%); m.p. 89–90 °C; IR (KBr cmꢀ1
)
3099, 3010, 2959, 2867, 1624, 1598, 1507, 1466, 1371,
1252, 1214, 1188, 1106, 1040, 1001, 909, 867, 822, 791,
1
738, 666; H NMR (CDCl3) 8.35 (1H, s, CHN), 7.19
(2H, d, J 7.5, ArH), 7.09 (2H, d, J 7.5, ArH), 4.81 (2H,
s, C5H4), 4.55 (2H, s, C5H4), 4.26 (5H, s, C5H5), 2.38
(3H, s, CH3); 13C NMR (CDCl3) 161.11, 150.69, 135.35,
130.13, 120.92, 80.95, 71.60, 69.66, 69.39, 21.39; m=z

C. Imrie et al. / Journal of Organometallic Chemistry 689 (2004) 1617–1622
1621
304, 303 (Mþ, 100), 302, 238, 182, 121, 91, 56. Anal.
Calc. for C18H17FeN: C, 71.4; H, 5.6; N, 4.6; [Mþ],
303.071039. Found: C, 70.9; H, 5.3; N, 4.6%; [Mþ],
303.071989.
(3H, t, CH3); 13C NMR (CDCl3) 159.91, 157.64, 146.12,
122.08, 115.37, 81.20, 71.48, 69.62, 69.27, 68.71, 32.35,
30.09, 30.03, 29.85, 29.79, 29.75, 26.48, 23.12, 14.56; m=z
503, 502, 501 (Mþ, 100), 417, 305, 304, 221, 214, 186,
121, 109, 69, 57, 43. Anal. Calc. for C31H43FeNO: C,
74.3; H, 8.6; N, 2.8; [Mþ], 501.269405. Found: C, 74.6;
H, 9.0; N, 2.6; [Mþ], 501.269387.
4.3.3. 4-Nitro-N-(ferrocenylmethylidene)aniline 4 (X ¼
4-NO2)
The general procedure was followed using ferrocene-
carboxaldehyde (200 mg, 0.93 mmol) and 4-nitroaniline
(129 mg, 0.93 mmol) except that the reaction mixture
was warmed to 50 °C in a water bath. The product was
isolated as a red solid and was recrystallized from cold
anhydrous methanol (286 mg, 92%); m.p. 183–185 °C;
IR (KBr cmꢀ1) 3102, 2914, 1631, 1593, 1578, 1506, 1341,
1223, 1111, 1052, 867, 828, 742, 703, 650, 492; 1H NMR
(CDCl3) 8.37 (1H, s, CHN), 8.26 (2H, d, J 7.7, ArH),
7.20 (2H, d, J 7.6, ArH), 4.84 (2H, s, C5H4), 4.60 (2H, s,
C5H4), 4.29 (5H, s, C5H5); 13C NMR (CDCl3) 164.51,
158.98, 145.32, 125.51, 121.48, 79.79, 72.62, 70.07,
69.93; m=z 335, 334 (Mþ, 100), 323, 288, 222, 214, 186,
167, 139, 121, 56. Anal. Calc. for C17H14FeN2O2: [Mþ],
334.040467. Found: [Mþ], 334.040503.
4.3.6. 4-Ferrocenyl-N-(ferrocenylmethylidene)aniline 4
(X ¼ 4-Fc)
The general procedure was followed using ferrocene-
carboxaldehyde (100 mg, 0.47 mmol) and 4-ferroceny-
laniline (130 mg, 0.47 mmol). The product was isolated
as a red solid and was recrystallized from cold anhy-
drous methanol (211 mg, 95%); m.p. 211–212 °C; IR
(KBr cmꢀ1) 3050, 1619, 1598, 1525, 1460, 1103, 1052,
1
1012, 894, 834, 512, 492; H NMR (CDCl3) 8.41 (lH, s,
CHN), 7.50 (2H, d, J 7.7, ArH), 7.13 (2H, d, J 7.8,
ArH), 4.83 (2H, s, C5H4), 4.67 (2H, s, C5H4), 4.52 (2H,
s, C5H4), 4.34 (2H, s, C5H4), 4.28 (5H, s, C5H5), 4.07
(5H, s, C5H5); 13C NMR (CDCl3) 160.85, 150.91,
136.80, 127.18, 121.18, 85.66, 81.03, 71.71, 70.02, 69.71,
69.44, 69.30, 66.75; m=z 474, 473 (Mþ), 471, 278, 277
(100), 275, 156, 121, 49. Anal. Calc. for C27H23Fe2N: C,
68.6; H, 4.9; N, 3.1; [Mþ], 473.052928. Found: C, 67.9;
H, 4.5; N, 3.1; [Mþ], 473.052125.
4.3.4. 4-Octyloxy-N-(ferrocenylmethylidene)aniline 4 (X ¼
4-OC8H17)
The general procedure was followed using ferrocene-
carboxaldehyde (100 mg, 0.47 mmol) and 4-octylox-
yaniline (104 mg, 0.47 mmol). The product was isolated
as a red solid and was recrystallized from cold anhydrous
4.4. Preparation of ferrocenylimines derived from 4-
formylphenylferrocene
methanol (182 mg, 93%); m.p. 71–72 °C; IR (KBr cmꢀ1
)
2921, 2861, 1631, 1512, 1473, 1302, 1249, 1190, 1117,
4.4.1. 4-Tetradecyloxy-N-[4-(4-ferrocenyl)benzylidene]
aniline 5 (X ¼ 4-OC14H29)
1
1038, 1005, 834, 736, 532, 505, 479; H NMR (CDCl3)
8.35 (1H, s, CHN), 7.15 (2H, d, J 8.6, ArH), 6.92 (2H, d,
J 8.6, ArH), 4.80 (2H, s, C5H4), 4.48 (2H, s, C5H4), 4.26
(5H, s, C5H5), 3.99 (2H, t, OCH2), 1.80 (2H, m, CH2),
1.47–1.29 (10H, m, CH2 ꢁ 5), 0.92 (3H, t, CH3); 13C
NMR (CDCl3) 159.92, 157.64, 146.10, 122.07, 115.38,
81.17, 70.06, 69.62, 69.27, 68.72, 32.23, 29.79, 29.73,
29.66, 26.47, 23.07, 14.52; m=z 418, 417 (Mþ, 100), 415,
305, 304, 221, 186, 121, 109, 43. Anal. Calc. for
C25H31FeNO: C, 72.0; H, 7.5; N, 3.3; [Mþ], 417.175504.
Found: C, 72.3; H, 7.3; N, 3.6; [Mþ], 417.175484.
The general procedure was followed as in 4.2 using 4-
formylphenylferrocene (100 mg, 0.34 mmol) and 4-tet-
radecyloxyaniline (104 mg, 0.34 mmol). The product was
isolated as an orange solid and was recrystallized from
cold anhydrous methanol (188 mg, 96%); m.p. 110–
112 °C; IR (KBr cmꢀ1) 2933, 2861, 1625, 1607, 1508,
1
1473, 1297, 1256, 1174, 1027, 845, 722, 546; H NMR
(CDCl3) 8.47 (lH, s, CHN), 7.82 (2H, d, J 8.3, ArH), 7.58
(2H, d, J 8.2, ArH), 7.25 (2H, d, J 8.8, ArH), 6.94 (2H, d,
J 8.8, ArH), 4.75 (2H, t, J 1.8, C5H4), 4.41 (2H, t, J 1.8,
C5H4), 4.07 (5H, s, C5H5), 4.01 (2H, t, J 5.6, OCH2), 1.80
(2H, m, CH2), 1.59–1.28 (22H, m, CH2 ꢁ 11), 0.90 (3H, t,
CH3); 13C NMR (CDCl3) 158.55, 158.15, 145.36, 143.37,
134.46, 129.07, 126.50, 122.53, 115.37, 84.36, 70.18,
69.97, 68.69, 67.11, 32.34, 30.08, 30.01, 29.83, 29.78,
29.72, 26.47, 23.11, 14.55; m=z 578, 577 (Mþ), 418, 417,
305, 290, 109 (100), 108, 69, 43. Anal. Calc. for
C37H47FeNO: C, 77.0; H, 8.2; N, 2.4; [Mþ], 577.300705.
Found: C, 77.3; H, 8.2; N, 2.2; [Mþ], 577.300679.
4.3.5. 4-Tetradecyloxy-N-(ferrocenylmethylidene)aniline
4 (X ¼ 4-OC14H29)
The general procedure was followed using ferrocene-
carboxaldehyde (100 mg, 0.47 mmol) and 4-tetradecy-
loxyaniline (143 mg, 0.47 mmol). The product was
isolated as a yellow crystalline solid and was recrystal-
lized from cold anhydrous methanol (221 mg, 94%);
m.p. 77–78 °C; IR (KBr cmꢀ1) 3097, 2923, 2872, 1631,
1502, 1472, 1244, 1103, 1015, 840, 798, 728, 505, 488; 1H
NMR (CDCl3) 8.35 (1H, s, CHN), 7.15 (2H, d, J 8.6,
ArH), 6.92 (2H, d, J 8.6, ArH), 4.80 (2H, s, C5H4), 4.48
(2H, s, C5H4), 4.25 (5H, s, C5H5), 3.98 (2H, t, OCH2),
1.82 (2H, m, CH2), 1.48–1.29 (22H, m, CH2 ꢁ 11), 0.91
4.4.2. 4-Ferrocenyl-N-[4-(4-ferrocenyl)benzylidene]ani-
line 5 (X ¼ 4-Fc)
The general procedure was followed as in 4.2 using
4-formylphenylferrocene (100 mg, 0.34 mmol) and

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C. Imrie et al. / Journal of Organometallic Chemistry 689 (2004) 1617–1622
4-ferrocenylaniline (95 mg, 0.34 mmol). The pyrex tube
was warmed to 50 °C during the reaction. The product
was isolated as a red solid and was recrystallized from
cold anhydrous methanol (172 mg, 92%); m.p. 260 °C
dec; IR (KBr cmꢀ1) 3090, 2358, 2336, 1629, 1612, 1563,
1530, 1179, 1108, 1009, 822, 532, 510; 1H NMR
(CDCl3) 8.52 (lH, s, CHN), 7.85 (2H, d, J 7.9, ArH),
7.59 (2H, d, J 7.9, ArH), 7.53 (2H, d, J 8.2, ArH), 7.22
(2H, d, J 8.0, ArH), 4.75 (2H, s, C5H4), 4.68 (2H, s,
C5H4), 4.41 (2H, s, C5H4), 4.35 (2H, s, C5H4), 4.08
(10H, s, C5H5); 13C NMR (CDCl3) 159.53, 150.31,
143.72, 137.52, 134.36, 129.26, 127.16, 126.55, 121.48,
85.49, 84.30, 70.31, 70.20, 70.03, 69.36, 67.15, 66.78;
m=z 549 (Mþ), 547, 501, 473, 417, 304, 290, 277, 274,
236, 186, 156, 139, 121, 109, 98, 83, 69, 57, 44, 39.
Anal. Calc. for C33H27Fe2N: C, 72.2; H, 5.0; N, 2.5;
[Mþ], 549.084229. Found: C, 72.3; H, 4.8; N, 2.7;
[Mþ], 549.084302.
4.7. Preparation of a ferrocenylimine derived from the
reaction of 4-ferrocenylaniline and 3,4,5-trimethoxybenz-
aldehyde
4.7.1. 4-Ferrocenyl-[3,4,5-(trimethoxybenzylidene)]ani-
line
The general procedure was followed using 3,4,5-tri-
methoxybenzaldehyde (100 mg, 0.51 mmol) and 4-fer-
rocenylaniline (142 mg, 0.51 mmol). The product was
isolated as a red solid and was recrystallized from cold
methanol (202 mg, 87%), m.p. 132–134 °C; IR (KBr
cmꢀ1) 3006, 1625, 1581, 1520, 1504, 1463, 1417, 1370,
1329, 1236, 1202, 1129, 999, 889, 860, 813, 750, 674, 624;
1H NMR (CDCl3) 8.45 (1H, s, CHN), 7.51 (2H, s,
ArH), 7.28 (1H, s, ArH), 7.21 (3H, s, ArH), 4.70 (2H, s,
C5H4), 4.37 (2H, s, C5H4), 4.09 (5H, s, C5H5), 3.98 (6H,
s, 2 ꢁ OCH3), 3.95 (3H, s, OCH3); 13C NMR (CDCl3)
159.26, 153.94, 127.15, 121.46, 106.19, 85.37, 70.08,
69.47, 66.81, 61.42, 56.69; m=z 457, 456, 455 (Mþ, 100),
363, 287, 277, 274, 261, 139, 121, 56, 43, 39. Anal. Calc.
for C26H25FeNO3: C, 68.6; H, 5.5; N, 3.1; [Mþ],
455.118416. Found: C, 68.5; H, 5.4; N, 3.1; [Mþ],
455.118383.
4.5. Preparation of ferrocenylimines derived from 40-
ferrocenyl-biphenyl-4-carbaldehyde
4.5.1. 4-Octyloxy-N-[4-(4-ferrocenylphenyl)benzylidene]-
aniline 6 (X ¼ 4-OC8H17)
The general procedure was followed as in 4.2 using 40-
ferrocenyl-biphenyl-4-carbaldehyde (50 mg, 0.14 mmol)
and 4-octyloxyaniline (31 mg, 0.14 mmol). The pyrex
tube was warmed to 50 °C during the reaction. The
product was isolated as an orange solid and was re-
crystallized from CH2Cl2–MeOH (69 mg, 87%). The
product was found to have an identical characterization
to that reported previously [9].
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4.5.2. 4-Tetradecyloxy-N-[4-ferrocenylphenyl)benzylidene]-
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The general procedure was followed as in 4.2 using 40-
ferrocenyl-biphenyl-4-carbaldehyde (50 mg, 0.14 mmol)
and 4-tetradecyloxyaniline (43 mg, 0.14 mmol). The
product was isolated as a yellow solid and was recrys-
tallized from CH2Cl2–MeOH (83 mg, 91%). The prod-
uct was found to have an identical characterization to
that reported previously [9].
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4.6.1. 4-Tetradecyloxy-N-{1-[4-(ferrocenylphenoxy)-phenyl]-
methylidene}aniline 7 (X ¼ 4-OC14H29)
ꢀ
ꢀ
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(4-ferrocenyl-phenoxy)-benzaldehyde (50 mg, 0.13 mmol)
and 4-tetradecyloxyaniline (40 mg, 0.13 mmol). The pyrex
tube was warmed to 50 °C during the reaction. The
product was isolated as a yellow solid and was recrystal-
lized from cold CH2Cl2–MeOH (78 mg, 90%). The
product was found to have an identical characterization
to that reported previously [9].
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