Further solvent-free reactions of ferrocenylaldehydes: Synthesis of 1,1′-ferrocenyldiimines and ferrocenylacrylonitriles

Article abstract of DOI:10.1016/j.jorganchem.2007.04.011

Grinding of 1,1′-ferrocenedicarboxaldehyde with a 2.2 molar equivalent of an aromatic amine in a solvent-free environment provided excellent yields of 1,1′-ferrocenyldiimines. After mixing the aldehyde and amines, a gum or melt formed which eventually solidified to the product. An analytically pure sample of the product was obtained by cold recrystallization. Grinding of ferrocenecarboxaldehyde and 4-substituted phenylacetonitriles under solvent-free conditions provided good yields of the corresponding ferrocenylacrylonitriles. The yield in this reaction was very low when the substituent group para to the acetonitrile group was electron-donating.

Full text of DOI:10.1016/j.jorganchem.2007.04.011

Journal of Organometallic Chemistry 692 (2007) 3443–3453
www.elsevier.com/locate/jorganchem
Further solvent-free reactions of ferrocenylaldehydes: Synthesis
of 1,10-ferrocenyldiimines and ferrocenylacrylonitriles
a,
a
a
a
Christopher Imrie *, Phumelele Kleyi , Vincent O. Nyamori , Thomas I.A. Gerber ,
b
b
Demetrius C. Levendis , Jennifer Look
Department of Chemistry,1 University of Port Elizabeth, P.O. Box 1600, Port Elizabeth 6000, South Africa
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa
a
b
Received 30 January 2007; received in revised form 10 April 2007; accepted 10 April 2007
Available online 20 April 2007
Dedicated to the memory of my Mother, Kathleen Mary Imrie.
Abstract
Grinding of 1,10-ferrocenedicarboxaldehyde with a 2.2 molar equivalent of an aromatic amine in a solvent-free environment provided
excellent yields of 1,10-ferrocenyldiimines. After mixing the aldehyde and amines, a gum or melt formed which eventually solidified to the
product. An analytically pure sample of the product was obtained by cold recrystallization. Grinding of ferrocenecarboxaldehyde and 4-
substituted phenylacetonitriles under solvent-free conditions provided good yields of the corresponding ferrocenylacrylonitriles. The
yield in this reaction was very low when the substituent group para to the acetonitrile group was electron-donating.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: 1,10-Ferrocenedicarboxaldehyde; Ferrocenylacrylonitrile compounds; 1,10-Ferrocenyldiimines; Green chemistry; Solvent-free synthesis
1. Introduction
metallic molecules, especially ferrocenes and ruthenocenes
since this field is relatively undeveloped. The ultimate aim
is to use knowledge on simple organometallic molecules
to gain an understanding on the molecular parameters
required for reactivity in the room temperature grinding
of reactants.
Ferrocenecarboxaldehyde (1) and acetylferrocene are
two important precursors of ferrocene derivatives, and
have been shown to be particularly amenable to reaction
under solvent-free conditions [3]. For example, it was
shown by Imrie et al. that 1 reacts with substituted anilines
to provide excellent yields of ferrocenylmonoimines after
just a few minutes of grinding [3a]. The reactions took
place in most cases at room temperature and the products
were isolated by cold recrystallization from a minimal
quantity of methanol. This current paper describes our lat-
est results on further reactions of 1 under solvent-free con-
ditions. Furthermore, it reports the first results on the
reactivity of 1,10-ferrocenedicarboxaldehyde under sol-
vent-free conditions.
The solvent-free approach to the synthesis of mole-
cules is an attractive one since the majority of solvents
are either toxic or flammable and add considerably to
the cost of an overall synthesis. In many instances, the
solvent-free approach allows shorter reaction times,
improved selectivities and easier separations and purifica-
tions than conventional solvents [1]. A monologue has
recently appeared on the subject of solvent-free reactions
and it provides an up-to-date account of the range of
synthetic reactions that have been investigated under sol-
vent-free conditions [2]. One of the current themes in our
research is to study the solvent-free synthesis of organo-
1
University of Port Elizabeth now forms part of the Nelson Mandela
Metropolitan University, Port Elizabeth, South Africa.
*
Corresponding author. Tel.: +27 415042823; fax: +27 415042573.
E-mail address: Christopher.Imrie@upe.ac.za (C. Imrie).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.04.011

3444
C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
2. Results and discussion
provides 4 (Fig. 1) in quantitative yield in a few minutes. In
contrast to the reactions described in Scheme 1, we found
that it was necessary to use an excess of the diamine to
achieve a high conversion.
2.1. Solvent-free synthesis of ferrocenylimines
Ferrocenylimines have been conventionally prepared by
heating a solution of the ferrocenylaldehyde and aromatic
amine in solvents such as methanol or ethanol [4]. This
approach usually involves heating the reactants for a few
hours under reflux; thermally sensitive ferrocenylimines
can suffer a degree of decomposition during this time. Dur-
ing our initial study [3a], it became apparent that 1 was
extremely reactive under solvent-free conditions. To inves-
tigate this further, we decided to look at its reactivity with
anilines and amines containing two amino functional
groups. The reactions with anilines are summarized in
Scheme 1 and the results again demonstrate the reactivity
of 1. The molar ratio of the reactants, 1:anilines was varied
from 1:2, 1:1 and 2:1. In all cases, bisferrocenylimines 2 and
3 were isolated and the excess unreacted starting materials
were recovered. The ratio 2:1 (aldehyde:aniline) had the
best atom economy and provided excellent yields of the
bisimines.
Despite the fact that the first synthesis of 1,10-ferrocen-
edicarboxaldehyde (5) (Scheme 2) was reported many years
ago, the synthesis of simple 1,10-ferrocenyldiimines
(Scheme 2) and other derivatives has not been researched
in-depth. This could be due in part to the fact that 5 is
not commercially available and the difficulties experienced
in its synthesis.
The starting materials used in the synthesis of 1,10-ferr-
ocenyldiimines were all commercially available apart from
5. The synthesis of 5 according to the available literature
methods [6] proved to be very inefficient, giving consis-
tently isolated yields of less than 10% and involved a
tedious work-up procedure. However, with the help of
modifications communicated separately to us by Loubser
and Kamounah [7], it was possible to modify the literature
method to give consistently higher yields. Synthesis of 1,10-
ferrocenyldiimines 6–12 was achieved by simply mixing and
grinding 5 with the aniline under solvent-free conditions in
a 1:2.2 mole ratio (Scheme 2).
The reactions occurred readily. In some cases a gum
formed and in others the mixture turned into a melt. Upon
solidification, 13C NMR was used to analyze the crude
product and to gauge the extent of the reaction. This was
easily followed by the disappearance of the carbonyl
(C@O) resonance peak of 5 and the appearance of a strong
resonance for the imine (C@N) functional group in the
range 155.00–165.00 ppm. Minimal amounts of anhydrous
methanol were used to recrystallize the products. The
results are given in Table 1.
Compound 4 has been previously reported by Lee et al.
[5] and was synthesized by the reaction of 1 with ethylene-
diamine in diethyl ether in the presence of either a drying
agent, magnesium sulfate or catalyst, RuCl2(PPh3)2. We
have found that simple grinding of 1 with ethylenediamine
N
CH
Fe
N
2
HC
In general, under the equivalent solvent-free conditions,
5 was less reactive than 1, justifying the slight excess of ani-
lines that were used in these reactions. In a few cases, in
order to improve the yield, the pyrex reaction tube was
immersed in a constant temperature water bath at 50 ꢁC.
The reaction did not work very well in cases where the ani-
line contained an electron-withdrawing group such as
nitro; this could be explained by the electrons being induc-
tively pulled from the amino group causing the aniline to
be less reactive in this type of reaction. The 1H NMR spec-
trum for the 1,10-ferrocenyldiimines showed a characteris-
tic peak in the region of 8.40–8.20 ppm for the imine
protons (CH@N). Its integration represented the two pro-
tons that are chemically equivalent.
Fe
H2N
NH2
N
CH
CHO
Fe
Fe
1
X
NH2
X
N
NH2
CH
NH2
H2N
Fe
N
N
CH
C
H
N
C
H
N
CH
Fe
Fe
Fe
Fe
3
4
Scheme 1. Solvent-free reactions of 1 with bis(amino) compounds that
provide isolated products.
Fig. 1. Structure of N,N0-ethylenebis[(ferrocenylmethylidene)amine].

C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
3445
X
grinding 1 with phenylacetonitriles in the presence of a cat-
alytic amount of piperidine (Scheme 3).
N
CH
CHO
CHO
No Solvent
Grind
H2N
+
The starting compounds were thoroughly ground
together and the resultant solids were allowed to dry in
the open air before being analysed by IR, H NMR and
Fe
Fe
X
CH
N
1
5
13C NMR spectrometry to determine the reaction pro-
gress. In most cases the reactions occurred readily and
this was characterized by the formation of a dark purple
melt. The reaction proved to be very favourable, espe-
cially when electron withdrawing-groups such as nitro
and trifluoromethyl were attached to the para position
of the phenylacetonitrile (see Table 2). In these cases,
the reaction was observed to be instantaneous. The strong
inductive effect of the electron-withdrawing group would
contribute to the activation of the methylene group taking
part in the reaction. In the case of an electron-donating
group such as methoxy on the para-position of the phe-
nylacetonitrile, the efficiency of the reaction dropped dras-
tically. An attempt to change the reaction conditions in
this instance, for example by heating, did not prove to
be very successful.
X
X= 4-OCH3 (6), 4-CH3 (7), 4-F (8), 4-Cl (9), 4-Br (10), 3,4,5-(Cl)3 (11), 4-Fc (12)
Scheme 2. Synthesis of 1,10-ferrocenyldiimines under solvent-free
conditions.
Table 1
Yields of 1,10-ferrocenyldiimines from the reaction of 1,10-ferrocenedicar-
boxaldehyde and substituted anilines under solvent-free conditions
Compound
Substituent X (Scheme 2)
Yield (%)a,b
6
4-OCH3
4-CH3
4-F
4-Cl
4-Br
98
98
82
96
95
74
91
7
8
9
10
11
12
a
3,4,5-(Cl)3
4-Fc
Yields are based on isolated products.
Imines were isolated and characterized by IR, NMR (1H, 13C), high
b
2.3. Electronic spectroscopy of ferrocenylacrylonitriles
resolution mass spectroscopy and elemental analysis.
The UV–Vis spectra of selected ferrocenylacrylonitriles
were recorded in acetonitrile (Fig. 2). Spectral comparisons
were made with unsubstituted ferrocene. Ferrocene exhib-
its two major bands at 327 and 445 nm, which have been
2.2. Solvent-free synthesis of ferrocenylacrylonitriles
Ferrocenecarboxaldehyde (1) is known to undergo
Knoevenagel condensations under classical homogeneous
conditions in ethanol with occasional necessary use of
Schlenk techniques or Dean-Stark trap apparatus [8]. Use
of inorganic supports such as aluminium oxide or silica
gel under solvent-free conditions has also been investigated
by Cooke et al. [9] and Stankovic et al. [10], respectively. In
their work they used either Al2O3 or SiO2 to catalyze the
condensation of ferrocenecarboxaldehyde with active
methylene compounds to provide good-to-excellent yields
of the ferrocenylmethylene in the range of 58–100%. How-
ever, the reactions involved 2–5 h of stirring the mixture
(solution or molten, depending on the active methylene
compound) and in some cases heat was required to
improve the efficiency. The extraction of the product from
the inorganic support using dichloromethane also makes
this approach less favourable in terms of its green chemis-
try credentials. Following a recent report by McClusky
et al. on the Knoevenagel reaction [11], it was decided to
attempt the synthesis of ferrocenylacrylonitriles by simply
1
1
1
1
assigned to A2g ! E2g and A1g ! E1g ligand field d–d
transitions [12].
In most cases, on substitution of the cyclopentadienyl
ring of ferrocene with conjugated substituents, a shift to
lower energy for the absorption would be anticipated.
Increased mixing of ligand orbitals with metal d-orbitals
is anticipated. There is a marked bathochromic shift of
the longer wavelength absorption as a result of conjugation
of the ferrocenyl group with a phenyl substituent. This is
evident on comparative analysis on the kmax of the unsub-
stituted ferrocene and those of ferrocenylacrylonitrile com-
pounds. Compound 18 exhibits the largest bathochromic
shift while 13 shows the smallest effect. The molar extinc-
tion coefficients were also determined and are listed in
Table 3.
Table 2
Yields of ferrocenylacrylonitriles from the reactions of ferrocenecarbox-
aldehyde and substituted phenylacetonitriles under solvent-free conditions
Compound
Substituent X (Scheme 3)
Yield (%)a,b
13
14
15
16
17
18
a
4-OCH3
4-Cl
4-F
4-CN
4-CF3
4-NO2
6
89
91
95
93
99
NC
C
O
H
No Solvent
C
X
CH
+
CH2CN
Fe
Fe
X
Yields are based on isolated products.
Ferrocenylacrylonitriles were characterized by IR, NMR (1H, 13C),
X= 4-OCH3 (13), 4-Cl (14), 4-F (15), 4-CN (16), 4-CF3 (17), 4-NO2 (18)
b
high resolution mass spectroscopy and elemental analysis.
Scheme 3. Solvent-free synthesis of ferrocenylacrylonitriles.

3446
C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
Table 4
20000
17
Comparative kmax values for ferrocenylacrylonitriles in different solvents
14
18
13
Compound
kmax (nm)
15000
10000
5000
Chloroform
Acetonitrile
Toluene
DMF
17
14
18
13
512
337
509
330
510
330
476
335
502
337
501
330
501
338
469
330
542
359
537
353
533
355
558
355
498
344
492
337
491
340
482
343
0
200
250
300
350
400
450
500
550
600
650
700
Wavelength (nm)
Fig. 2. UV–Vis spectra of ferrocenylacrylonitriles in acetonitrile.
ties [14]. Cooke et al. have also reported kmax values of sim-
ilar ferrocenyl derivatives. In their results toluene,
dichloromethane and DMF were used as solvents for deter-
mining the solvatochromic behaviour [9]. In our results,
compound 18 (Fig. 3) exhibited a significant bathochromic
shift when the solvent was changed from toluene to DMF
whereas compound 14 and 17 showed a hypsochromic shift
(Table 4). This warrants further examination with regards
to their NLO properties. 3-Ferrocenyl-2-(4-methoxyphe-
nyl)acrylonitrile 13 did not show much behavioural differ-
ence in the different solvents.
Table 3
Wavelength maxima and extinction coefficients of ferrocenylacrylonitriles
in acetonitrile
Compound
k )
max/nm (emax/molꢀ1 dm3 cmꢀ1
Ferrocene
445 (97), 327 (57)
18
17
14
13
537 (4646), 353 (19541)
509 (2705), 330 (19852), 274 (8259)
501 (2380), 330 (19394), 274 (8443)
492 (2145), 337 (20018)
2.4. Cyclic voltammetry of ferrocenylacrylonitriles
Ferrocenylacrylonitriles were also investigated for solva-
tochromic behaviour. Compounds that exhibit solvato-
chromic behaviour are known to exhibit NLO properties
[13]. The UV–Vis spectrum of each compound was
recorded in a range of solvents of differing polarity. The
solvents used were chloroform, acetonitrile, toluene and
dimethylformamide (DMF). Results are shown graphically
in Fig. 3 for compound 18 in toluene and DMF. The com-
parative kmax for each compound in all solvents are listed in
Table 4.
The redox behaviour of selected ferrocenylacrylonitriles
prepared in this study was evaluated using cyclic voltam-
metry. The observed redox behaviour of the respective
complexes are all reported with regard to the reversible
redox wave of unsubstituted ferrocene, which showed an
E1/2 at 429.5 mV under the given conditions in acetonitrile
with tetrabutylammonium perchlorate (TBAP) as back-
ground electrolyte. The observed couples were all revers-
ible, where reversibility in this case is taken to imply that
the difference between anodic and cathodic peak potentials
is less than 80 mV, as well as the peak current ratios (ipa/ipc)
being approximately equal to unity (0.91–1.02). Derivatiza-
tion of ferrocene gave a positive shift for all compounds
studied, indicating that placing a substituent on the cyclo-
pentadienyl ring of ferrocene made the ferrocene group
harder to oxidise. The extent of shift, however, was depen-
dant on the nature of the substituent. The p-nitro substitu-
ent on the phenyl ring (compound 18) showed the most
positive shift while the p-methoxy substituent on the phenyl
ring (compound 13) showed the least. Half-wave potentials
of ferrocene and selected ferrocenylacrylonitriles are listed
in Table 5 with corresponding anodic Epa and cathodic Epc
peak potentials.
cis-[1-Ferrocenyl-2-(4-nitrophenyl)ethylene] synthesized
by Green et al. was one of the first examples of ferrocenyl
derivatives that exhibited solvatochromic behaviour and
was found to have second-order nonlinear optical proper-
DMF
20000
Toluene
15000
10000
5000
0
2.5. X-ray crystallography
290
340
390
440
490
540
590
640
690
The crystal and molecular structures of 16 and 17 were
determined by single crystal X-ray crystallography. The
ORTEP diagrams of the two molecules showing their num-
Wavelength (nm)
Fig. 3. Electronic spectra of compound 18 in toluene and DMF.

C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
3447
Table 5
Table 6
˚
Electrochemical data of ferrocene and ferrocenylacrylonitriles in
acetonitrile
Selected bond lengths (A) and angles (ꢁ) for 16
˚
Bond length (A)
Bond angles (ꢁ)
Compound
Epa (mV)
Epc (mV)
E1/2 (mV)
C11–C12
C10–C11
C12–C13
C12–C14
C13–N1
C17–C20
C20–N2
C6–C7
1.351(2)
1.447(3)
1.436(2)
1.488(3)
1.144(2)
1.44(3)
1.136(3)
1.413(2)
1.414(3)
C11–C12–C13
C11–C12–C14
C12–C11–C10
C13–C12–C14
C12–C11–H11
C10–C11–H11
C16–C17–C20
N1–C13–C12
N2–C20–C17
120.4(2)
123.7(2)
131.2(2)
115.9(2)
114.4
Ferrocene
465
670
659
690
629
394
597
582
624
560
429.5
633.5
620.5
657
17
14
18
13
594.5
114.4
118.4(2)
177.4(2)
176.8(3)
C7–C8
bering schemes are shown in Fig. 4. Selected bond lengths
and angles for 16 and 17 are provided in Tables 6 and 7,
respectively.
In compound 16, the nitrile-ethylene and cyano-phenyl
moieties are almost coplanar with the ferrocenyl Cp ring.
The torsion angles of C(6)–C(10)–C(11)–C(12), C(10)–
C(11)–C(12)–C(13) and C(13)–C(12)–C(14)–C(19) are
ꢀ2.7(3)ꢁ, 2.3(3)ꢁ and ꢀ7.4(2)ꢁ, respectively. The ferrocenyl
rings have an eclipsed conformation with a 1.9ꢁ staggering
Table 7
˚
Selected bond lengths (A) and angles (ꢁ) for 17
˚
Bond length (A)
Bond angles (ꢁ)
C11–C12
C10–C11
C12–C13
C12–C14
C13–N1
C17–C20
C6–C7
1.354(3)
1.438(3)
1.448(3)
1.474(3)
1.139(3)
1.487(4)
1.402(4)
1.407(3)
C11–C12–C13
C11–C12–C14
C12–C11–C10
C13–C12–C14
C12–C11–H11
C10–C11–H11
C16–C17–C20
N1–C13–C12
120.1(2)
124.0(2)
128.3(2)
115.6(2)
116(2)
116(2)
120.2(3)
175.2(3)
˚
angle. The single C–C bond length C10–C11, 1.448(2) A, is
shorter than C12–C14, 1.488(2) A. This difference in bond
˚
lengths is not observed in the comparable molecules 1-ferr-
ocenyl-1-phenyl-2-(4-cyanophenyl)ethylene [15] and 2-ferr-
ocenyl-1-(4-(trifluoromethyl)phenyl)propene [15], where
the substituent on the ethylene group is not nitrile. A sim-
ilar difference was observed in the molecule, 2,5-dicyano-3-
diferrocenylhexa-2,4-dienedinitrile [16]. In contrast to 16,
molecules of compound 17 have the nitrile-ethylene and
cyano-phenyl moieties twisted out of the plane of the ferr-
C7–C8
ocenyl Cp ring. The torsion angles of C(9)–C(10)–C(11)–
C(12), C(10)–C(11)–C(12)–C(13) and C(19)–C(14)–C(15)–
C(16) are 32.9(4)ꢁ, 6.8(4)ꢁ and ꢀ2.5(4)ꢁ, respectively. The
ferrocenyl rings are again eclipsed, with a 3.3ꢁ staggering
angle. The single C–C bond lengths around the ethylene
˚
are similar to 16: C10–C11, 1.438(3) A and C12–C14,
1.474(3) A. The only noteworthy intermolecular interac-
˚
tions is that between two fluorine atoms, F20ꢁ ꢁ ꢁF20 related
by a centre of inversion. However, since CF3 is disordered,
this distance may not really be significant.
3. Conclusion
Solvent-free reaction of ferrocenecarboxaldehyde with
diamines provided excellent yields of the corresponding dii-
mines. The solvent-free method was also successfully
applied in the synthesis of 1,10-ferrocenyldiimines by the
reaction of 1,10-ferrocenedicarboxaldehyde and a range of
substituted anilines. The products were isolated in good
yield with minimum work-up. Solvent-free synthesis of fer-
rocenylacrylonitriles using the Knoevenagel reaction was
successful. The synthetic procedure was very simple and
the products were generally obtained in very good yield.
4. Experimental
4.1. Purification and characterization of the materials
All reactions, unless otherwise stated, were performed
under an inert atmosphere of dry nitrogen. For more sen-
sitive manipulations, standard Schlenk techniques were
applied and pure argon was used. n-Butyllithium (1.6 M
and 10.0 M in hexanes), N,N,N0,N0-tetramethylethylenedi-
Fig. 4. Molecular structures of compounds 16 and 17 showing the atom
numbering scheme.

3448
C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
amine (packaged under nitrogen in sealed bottles), ferro-
cene, ferrocenecarboxaldehyde and the phenylacetonitriles
were obtained from the Sigma–Aldrich Chemical Com-
pany, Milwaukee, USA. Thin layer chromatography was
performed on aluminium-backed silica gel or Merck silica
gel 60 F254 (1.5 mm) as adsorbent in a variety of solvent
systems using the ascending technique. Plates were ana-
lysed under ultraviolet light. Column chromatography
was conducted either on silica gel 60, particle size 0.063–
0.200 mm (70–230 mesh ASTM) or neutral alumina, parti-
cle size 0.063–0.200 mm (70–230 mesh ASTM). Unless
otherwise stated, all recrystallizations were performed at
room temperature. If more than one solvent was used to
perform the recrystallization, two different annotations
are used, e.g., dichloromethane/ethanol or dichlorometh-
ane/hexane denotes that a mixture of two solvents was
used, whereas dichloromethane-ethanol denotes that
dichloromethane was used to dissolve the solid and the
slow addition of ethanol resulted in crystallization.
Melting points were determined on an Electrothermal
IA 900 series digital melting point apparatus and are
uncorrected. Infrared spectra were recorded on either, a
Perkin–Elmer 1600 series instrument, a Nicolet Magna
550 Fourier Transform spectrophotometer or on a Digi-
Lab FTS 3100 Excalibur HE Series, packaged to DigiLab
Resolution 4.0 software with solid samples prepared as
potassium bromide disks and solution samples in sodium
chloride solution cells. Microanalyses were obtained on a
Carlo Erba EA 1108 elemental analyser. Fast atomic
bombardment (FAB) and high resolution (EI) mass spec-
tra were recorded on a micromass autospec-Tof mass
spectrometer at the University of the North West in
South Africa. NMR spectra were recorded on a Bruker
AX (300 MHz) spectrometer at ambient temperatures.
1H NMR spectra were referenced internally using residual
protons in the deuterated solvent and values reported
relative to tetramethylsilane (d 0.00). 13C NMR spectra
were similarly referenced internally to the solvent reso-
nance with values reported relative to tetramethylsilane
(d 0.00). Electrochemical data were obtained by cyclic
voltammetry with a BASi Epsilon-EC instrument using
version 1.50.69_XP software. A platinum working elec-
trode, platinum-wire auxiliary electrode and silver/silver
chloride reference electrode were used with 3 M sodium
chloride filling in a single-compartment-cell configuration.
Solution volumes of ca. 10 cm3 were used that were ca.
10ꢀ3 M in compound. Anhydrous acetonitrile was used
with the supporting electrolyte, TBAP which was present
in 0.1 M concentration. Solutions were deaerated by
nitrogen bubbling for ca. 15 min and were maintained
Solution concentrations of the ferrocenylacrylonitriles
were in the range 5 · 10ꢀ3 M.
4.2. Solvent-free synthesis of ferrocenylimines: general
procedure for the reaction of
ferrocenylmonocarboxaldehydes and aromatic amines
The ferrocenylmonocarboxaldehyde and aniline (equi-
molar 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 (ca.
25 ꢁC). In some cases, a gum formed and in others the mix-
ture turned into a melt. The pyrex tube was sealed and then
placed on a shaker for approximately 30 min at room tem-
perature. In cases where the starting materials were less
reactive, the pyrex tube was immersed in a constant tem-
perature water bath at 50 ꢁC. The samples were then placed
under a high vacuum overnight. Initial characterization of
the ferrocenylimine was carried out by IR spectroscopy
(KBr disc). This showed the disappearance of the carbonyl
absorption of the aldehyde at approximately 1680 cmꢀ1
and the appearance of a strong band between 1615 and
1635 cmꢀ1 for the imine. The ferrocenylimines were charac-
1
terized by H, 13C, mass spectroscopy and microanalysis.
4.2.1. 3,4,5-Trichloro-N-(ferrocenylmethylidene)aniline
The general procedure in Section 4.2 was followed using
ferrocenecarboxaldehyde (1) (100 mg, 0.47 mmol) and
3,4,5-trichloroaniline (93 mg, 0.47 mmol). The product
was isolated as a red crystalline solid and was recrystallized
from cold anhydrous methanol (167 mg, 91%); m.p. 97 ꢁC;
IR (KBr, cmꢀ1) 3079, 2888, 1619, 1571, 1541, 1426, 1374,
1253, 1226, 1188, 1143, 1105, 1040, 1004, 947, 861, 819,
1
803, 780, 492, 477; H NMR (CDCl3) 8.34 (1H, s, CHN),
7.19 (2H, s, ArH), 4.81 (2H, s, C5H4), 4.57 (2H, s, C5H4),
4.27 (5H, s, C5H5); 13C NMR (CDCl3) 164.14, 152.23,
134.68, 127.76, 121.50, 79.74, 72.45, 69.88, 69.80; m/z
(EI) 393 (M++2, 93%), 392 (M++1, 21%), 391 (M+,
100%), 272 (10), 270 (10), 237 (10), 235 (20), 228 (12),
202 (15), 200 (35), 199 (13), 186 (11), 181 (13), 164 (30),
121 (99). Anal. Calc. for C17H12Cl3FeN: C, 52.0; H, 3.1;
N, 3.6; [M+], 390.938472. Found: C, 51.9; H, 3.1; N,
3.3%; [M+], 390.938479.
4.2.2. 4-[4-(Ferrocenylmethyleneamino)benzyl]-N-
(ferrocenylmethylene)benzenamine (2)
The general procedure in Section 4.2 was followed
except that 2 molar equivalents of ferrocenecarboxalde-
hyde (200 mg, 0.93 mmol) and 1 molar equivalent of 4,40-
methylenedianiline (93 mg, 0.47 mmol) was used. The
product was isolated as a orange solid and was recrystal-
lized from cold anhydrous CHCl3–MeOH (225 mg, 81%);
m.p. 128 ꢁC; IR (KBr, cmꢀ1) 3083, 2923, 1628, 1596,
1503, 1467, 1412, 1370, 1327, 1251, 1219, 1192, 1169,
under
a nitrogen stream at ambient temperatures
(25 2 ꢁC). Calculation of E1/2 values was by averaging
the anodic and cathodic peak potentials. Scans were car-
ried out at a scan rate of 100 mV/s. Electronic spectra
were obtained with a Perkin–Elmer 330 spectrophotome-
ter. The sample path length or cell width was 0.1 cm
and the sample holder tube was quartz for all samples.
1
1105, 1043, 1002, 966, 823, 748, 703, 638, 596, 483; H
NMR (CDCl3) 8.36 (2H, s, CHN), 7.22 (4H, d, J 8.3,
ArH), 7.13 (4H, d, J 8.0, ArH), 4.82 (4H, s, C5H4), 4.51

C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
3449
(4H, s, C5H4), 4.26 (10H, s, C5H5), 4.01 (2H, s, CH2); 13C
NMR (CDCl3) 161.36, 151.20 138.71, 130.04, 121.17,
80.83, 71.71, 69.69, 69.45, 41.36; m/z (FAB) 590 (M+,
98%), 525 (10), 487 (8), 394 (15), 302 (20), 289 (15), 274
(8), 224 (5), 212 (8), 179 (12), 154 (100), 136 (86), 121
(36). Anal. Calc. for C35H30Fe2N2: C, 71.2; H, 5.1; N,
4.7; [M+], 590.110803. Found: C, 70.6; H, 5.2; N, 4.7%;
[M+], 590.110778.
165.00 ppm). Further purification was achieved by minimal
washing using cold anhydrous methanol. Sample purity
was confirmed by H NMR, IR spectroscopy, mass spec-
1
troscopy and microanalysis.
4.3.1. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-
(4-methoxyaniline) (6)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (150 mg, 0.62 mmol)
and 4-methoxyaniline (170 mg, 1.38 mmol). The product
was isolated as a red solid and was recrystallized from cold
anhydrous methanol (275 mg, 98%); m.p. 150 ꢁC; IR (KBr,
cmꢀ1) 3064, 2999, 2958, 2833, 1622, 1579, 1505, 1470, 1290,
4.2.3. 4-[4-(Ferrocenylmethyleneamino)phenethyl]-N-
(ferrocenylmethylene)benzenamine (3)
The general procedure in Section 4.2 was followed
except that 2 molar equivalents of ferrocenecarboxalde-
hyde (200 mg, 0.93 mmol) and 1 molar equivalent 4,40-dia-
minobibenzyl (103 mg, 0.47 mmol) was used. The product
was isolated as an orange solid and was recrystallized from
cold anhydrous CHCl3–MeOH (245 mg, 86%); m.p.
191 ꢁC; IR (KBr, cmꢀ1) 3025, 2913, 2886, 1622, 1595,
1506, 1465, 1411, 1369, 1325, 1250, 1220, 1192, 1169,
1
1244, 1216, 1033, 827, 784, 722, 638; H NMR (CDCl3)
8.29 (2H, s, CHN), 7.10 (4H, d, J 8.8, ArH), 6.85 (4H, d,
J 8.8, ArH), 4.87 (4H, t, J 1.7, C5H4), 4.52 (4H, t, J 1.7,
C5H4), 3.83 (6H, s, 2 · OCH3); 13C NMR (CDCl3)
158.89, 158.19, 145.76, 122.24, 114.71, 82.45, 72.38,
70.29, 55.86; m/z (EI) 453 (M++1, 8%), 452 (M+, 26%),
358 (100), 356 (6), 328 (8), 312 (11), 254 (7), 191 (12), 190
(26), 165 (11), 163 (10), 152 (7), 122 (7), 121 (70), 56 (15),
32 (18). Anal. Calc. for C26H24FeN2O2: [M+],
452.118717. Found: [M+], 452.118698.
1
1105, 1045, 1002, 839; 820, 639, 479; H NMR (CDCl3)
8.36 (2H, s, CHN), 7.19 (4H, d, J 8.4, ArH), 7.10 (4H, d,
J 8.4, ArH), 4.82 (4H, t, J 1.9, C5H4), 4.50 (4H, t, J 1.8,
C5H4), 4.27 (10H, s, C5H5), 2.96 (4H, s, 2 · CH2); 13C
NMR (CDCl3) 161.30, 151.10, 139.20, 129.65, 121.01,
80.91, 71.66, 69.69, 69.41, 37.93; m/z (FAB) 604 (M+,
55%), 307 (45), 289 (28), 273 (8), 212 (15), 180 (8), 154
(100), 136 (85), 121 (15). Anal. Calc. for C36H32Fe2N2:
[M+], 604.126874. Found: [M+], 604.126874.
4.3.2. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-
(4-methylaniline) (7)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (150 mg, 0.62 mmol)
and 4-aminotoluene (146 mg, 1.36 mmol). The product was
isolated as a red solid and was recrystallized from cold
anhydrous methanol (255 mg, 98%); m.p. 107 ꢁC; IR
(KBr, cmꢀ1) 3022, 2915, 2855, 1622, 1595, 1508, 1466,
1373, 1329, 1250, 1216, 1189, 1169, 1042, 1021, 968, 820,
786, 535; 1H NMR (CDCl3) 8.31 (2H, s, CHN), 7.13
(4H, d, J 8.2, ArH), 7.04 (4H, d, J 8.3, ArH), 4.87 (4H, t,
J 1.8, C5H4), 4.54 (4H, t, J 1.8, C5H4), 2.36 (6H, s,
2 · CH3); 13C NMR (CDCl3) 160.02, 150.14, 135.65,
130.15, 120.99, 82.20, 72.58, 70.47, 21.41; m/z (EI) 421
(M++1, 10), 420 (M+, 31%), 329 (6), 238 (8), 182 (4), 91
(5) 32 (22), 28 (100). Anal. Calc. for C26H24FeN2: C,
74.3; H, 5.8; N, 6.7 [M+], 420.12889. Found: C, 73.7; H,
5.7; N, 6.5%; [M+], 420.128903.
4.2.4. N,N0-Ethylenebis[(ferrocenylmethylidene)amine] (4)
[17]
Ferrocenecarboxaldehyde (400 mg, 1.87 mmol) and eth-
ylenediamine (100 mg, 1.66 mmol) were added together
and ground using a mortar and pestle. The yellow paste
was placed into a glass tube fitted with a ground glass joint
and the solid was placed on a vacuum pump overnight. The
product was obtained as a yellow solid and identified as
N,N-ethylenebis(ferrocenylmethylidene)amine (4) (380 mg,
83%).
4.3. General procedure for the synthesis of ferrocenyldiimines
from 1,10-ferrocenedicarboxaldehyde and anilines
1,10-Ferrocenedicarboxaldehyde (5) (1 molar equivalent)
and a substituted aniline (2.2 molar equivalent) 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 (ca. 25 ꢁC). 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 temperature (25 ꢁC). The samples were
then placed under a high vacuum overnight. Initial charac-
terization of the ferrocenylimine was carried out by 13C
NMR spectroscopy (CDCl3). This indicated a disappear-
ance of the carbonyl (C@O) resonance peak of the 1,10-fer-
rocenedicarboxaldehyde and showed a strong resonance
for the imine (C@N) functional group (range 155.00–
4.3.3. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-
(4-fluoroaniline) (8)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (150 mg, 0.62 mmol)
and 4-fluoroaniline (151 mg, 1.36 mmol) except that reac-
tion mixture in the pyrex tube was initially immersed in a
constant temperature water bath at 50 ꢁC for 1 h. The
product was isolated as a maroon solid and was recrystal-
lized from cold anhydrous methanol (217 mg, 82%); m.p.
112 ꢁC; IR (KBr, cmꢀ1) 3090, 2862, 1621, 1593, 1503,
1467, 1372, 1328, 1251, 1225, 1212, 1182, 1095, 1028,
1
939, 829, 797, 728, 642, 531, 480, 348; H NMR (CDCl3)
8.27 (2H, s, CHN), 7.02 (8H, m, ArH), 4.88 (4H, s,
C5H4), 4.55 (4H, s, C5H4); 13C NMR (CDCl3) 161.72,

3450
C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
(1C, d, JCaF 183.4, Ca), 159.70, 148.74, 122.35 (2C, d, JCcF
8.3, Cc) 116.19 (2C, d, JCbF 22.4, Cb), 82.00, 72.63, 70.51;
m/z (EI) 429 (M++1, 57%), 428 (M+, 100), 426 (13), 333
(33), 242 (28), 186 (23), 95 (11). Anal. Calc. for
C24H18F2FeN2: C, 67.3; H, 4.2; N, 6.5; [M+], 428.078744.
Found: C, 67.6; H, 4.1; N, 6.0%; [M+], 428.078711.
(CDCl3) 8.22 (2H, s, CHN), 7.06 (4H, s, ArH), 4.92 (4H,
t, J 1.8, C5H4), 4.60 (4H, t, J 1.8, C5H4); 13C NMR
(CDCl3) 162.42, 151.12, 134.80, 128.39, 121.31, 81.26,
73.21, 70.98; m/z (EI) 598 (M+, 16%), 307 (18), 289 (10),
200 (5), 180 (7), 154 (100), 136 (84), 120 (15). Anal. Calc.
for C24H14Cl6FeN2: C, 48.1; H, 2.4; N, 4.7; [M+],
595.863754. Found: C, 47.6; H, 2.3; N, 4.0%; [M+],
595.863804.
4.3.4. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-
(4-chloroaniline) (9)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (150 mg, 0.62 mmol)
and 4-chloroaniline (174 mg, 1.36 mmol). The product was
isolated as a red solid and was recrystallized from cold
anhydrous methanol (275 mg, 96%); m.p. 144 ꢁC; IR
(KBr, cmꢀ1) 3101, 3081, 2861, 1624, 1580, 1489, 1470,
1372, 1329, 1252, 1220, 1188, 1169, 1093, 1043, 1031,
1011, 940, 875, 824, 763, 657; 1H NMR (CDCl3) 8.26
(2H, s, CHN), 7.27 (4H, d, J 8.3, ArH), 7.01 (4H, d, J
8.6, ArH), 4.89 (4H, t, J 1.7, C5H4), 4.56 (4H, t, J 1.7,
C5H4); 13C NMR (CDCl3) 161.06, 151.09, 131.44, 129.59,
122.29, 81.86, 72.77, 70.63; m/z (EI) 460 (M+, 17%), 308
(6), 258 (4), 242 (13), 186 (3), 178 (11), 121 (5), 32 (17),
28 (100). Anal. Calc. for C24H18Cl2FeN2: C, 62.5; H, 3.9;
N, 6.1; [M+], 460.019643. Found: C, 62.2; H, 3.9; N,
5.5%; [M+], 460.019598.
4.3.7. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-
(4-ferrocenylaniline) (12)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (100 mg, 0.41 mmol)
and 4-ferrocenylaniline (230 mg, 0.83 mmol). The product
was isolated as an orange solid and was recrystallized from
cold anhydrous CHCl3–MeOH (284 mg, 91%); m.p. 120–
121 ꢁC; IR (KBr, cmꢀ1) 3089, 2863, 1621, 1593, 1521,
1
1452, 1219, 1105, 1001, 889, 821, 504; H NMR (CDCl3)
8.40 (2H, s, CHN), 7.46 (4H, d, J 8.5, ArH), 7.12 (4H, d,
J 8.4, ArH), 4.93 (4H, t, J 1.7, C5H4), 4.65 (4H, t, J 1.8,
C5H4), 4.58 (4H, t, J 1.8, C5H4), 4.33 (4H, t, J 1.8,
C5H4), 4.06 (10H, s, C5H5); 13C NMR (CDCl3) 169.99,
159.78, 137.23, 127.19, 121.28, 85.47, 82.24, 72.75, 70.59,
70.03, 69.35, 66.80; m/z (FAB) 757 (M+, 31%), 407 (8),
307 (15), 288 (10), 276 (8), 260 (5), 180 (6), 154 (100), 136
(33), 120 (16). Anal. Calc. for C44H36Fe3N2: [M+],
757.069192. Found: [M+], 757.069439.
4.3.5. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-
(4-bromoaniline) (10)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (150 mg, 0.62 mmol)
and 4-bromoaniline (234 mg, 1.36 mmol). The product was
isolated as a red solid and was recrystallized from cold
anhydrous methanol (324 mg, 95%); m.p. 137 ꢁC; IR
(KBr, cmꢀ1) 3082, 2863, 1624, 1577, 1488, 1469, 1329,
1252, 1219, 1189, 1169, 1102, 1072, 1032, 1006, 824, 758;
1H NMR (CDCl3) 8.26 (2H, s, CHN), 7.42 (4H, d, J 8.6,
ArH), 6.95 (4H, d, J 8.6, ArH), 4.89 (4H, t, J 1.7, C5H4),
4.56 (4H, t, J 1.8, C5H4); 13C NMR (CDCl3) 161.15,
151.54, 132.56, 122.70, 119.29, 81.81, 72.82, 70.65; m/z
(FAB) 550 (M++2, 100%), 548 (M+, 51), 395 (8), 308
(29), 290 (9), 249 (7), 222 (9), 211 (6), 167 (33), 154 (89),
136 (82), 120 (17). Anal. Calc. for C24H18Br2FeN2: C,
52.4; H, 3.3; N, 5.1; [M+], 547.918610. Found: C, 52.0;
H, 3.3; N, 4.8%; [M+], 547.918244.
4.4. General procedure for the solvent-free synthesis of
ferrocenylacrylonitrile compounds
Into a pyrex tube fitted with a ground glass joint, was
added an equimolar quantity of ferrocenemonocarboxalde-
hyde and a substituted phenylacetonitrile. The compounds
were thoroughly mixed (ground in case of two solids). One
or two drops of piperidine was introduced and allowed to
mix thoroughly using a glass rod at room temperature
(ca. 25 ꢁC). The pyrex tube was sealed and then placed
on a shaker for approximately 30 min at room tempera-
ture. The samples were then allowed to dry in open air
before being placed on a pump. Initial characterization of
the ferrocenylacrylonitrile was by NMR (1H and 13C)
and IR spectroscopy (KBr disc). In a typical case, the
13C NMR spectrum showed the disappearance of the car-
bonyl resonance and the appearance of resonance peaks
for the alkene. The carbonyl absorption band in the IR
spectrum disappeared and the intense band for the nitrile
group appeared at approximately 2200 cmꢀ1. The products
were purified for microanalysis and mass spectrometry
using preparative TLC plates or column chromatography
on silica gel.
4.3.6. N,N0-(Ferrocene-1,10-diyldimethylylidene)di-(3,4,5-
trichloroaniline) (11)
The general procedure was followed as in Section 4.3
using 1,10-ferrocenedicarboxaldehyde (150 mg, 0.62 mmol)
and 3,4,5-trichloroaniline (270 mg, 1.37 mmol) except that
the reaction mixture in the pyrex tube was initially
immersed in a constant temperature water bath at 50 ꢁC
for 1 h. The product was isolated as an orange solid and
was recrystallized from cold anhydrous methanol
(275 mg, 74%); m.p. 180 ꢁC; IR (KBr, cmꢀ1) 3070, 2887,
1626, 1572, 1541, 1473, 1426, 1374, 1254, 1226, 1188,
4.4.1. 3-Ferrocenyl-2-(4-methoxyphenyl)acrylonitrile (13)
The general procedure was followed as in Section 4.4
using ferrocenecarboxaldehyde (200 mg, 0.93 mmol) and
4-methoxyphenylacetonitrile (138 mg, 0.94 mmol) except
that the reaction mixture was heated to 80 ꢁC in a constant
1
1142, 1027, 938, 874, 859, 807, 782, 690, 661; H NMR

C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
3451
temperature water bath. The mixture formed a melt that
was placed on a shaker for 1 h and was then allowed to
dry in air overnight to form a red solid. The product was
further subjected to column chromatography using hex-
ane/diethyl ether (6:1) as the eluting solvent to achieve
143.61, 131.36, 127.32 (2C, d, JCcF 8.2, Cc), 119.42,
116.46 (2C, d, JCbF 22.0, Cb), 106.03, 77.66, 71.99, 70.49,
70.24; m/z (EI) 333 (M++1, 18%), 332 (M+, 100), 331
(55), 266 (85), 240 (25), 239 (94), 190 (24), 184 (26), 183
(94), 182 (10), 164 (14), 163 (25), 157 (16), 121 (73), 95
(12), 56 (56), 43 (16), 39 (24). Anal. Calc. for C19H14FFeN:
C, 68.9; H, 4.3; N, 4.2; [M+], 332.053792. Found: C, 68.3;
H, 4.3; N, 3.7%; [M+], 332.053805.
red crystals (18 mg, 6%); m.p. 92 ꢁC; IR (KBr, cmꢀ1
)
3010, 2968, 2935, 2841, 2214, 1605, 1515, 1457, 1424,
1252, 1184, 1107, 1041, 1001, 831, 821, 499, 481; 1H
NMR (CDCl3) 7.55 (2H, d, J 8.9, ArH), 7.27 (1H, s,
CH), 6.96 (2H, d, J 8.9, ArH), 4.96 (2H, t, J 1.9, C5H4),
4.52 (2H, t, J 1.9, C5H4), 4.25 (5H, s, C5H5), 3.87 (3H, s,
OCH3); 13C NMR (CDCl3) 160.11, 141.51, 127.74,
126.86, 119.68, 114.86, 106.85, 78.20, 71.65, 70.28, 70.16,
55.86; m/z (EI) 344 (M++1, 47%), 343 (M+, 100), 340
(13), 278 (19), 251 (23), 195 (18), 152 (16), 121 (25), 56
(10). Anal. Calc. for C20H17FeNO: [M+], 343.065954.
Found: [M+], 343.065902.
4.4.4. 3-Ferrocenyl-2-(4-cyanophenyl)acrylonitrile (16)
The general procedure was followed as in Section 4.4
using ferrocenecarboxaldehyde (200 mg, 0.93 mmol) and
4-cyanophenylacetonitrile (132 mg, 0.93 mmol). A maroon
paste was obtained upon grinding. Upon drying, the prod-
uct was isolated as a dark red solid which was further sub-
jected to TLC preparative plates using hexane/diethyl ether
(1:1) to achieve maroon crystals (300 mg, 95%); m.p.
140 ꢁC; IR (KBr, cmꢀ1) 3100, 3024, 2933, 2226, 2213,
1605, 1581, 1458, 1411, 1380, 1308, 1255, 1176, 1104,
4.4.2. 3-Ferrocenyl-2-(4-chlorophenyl)acrylonitrile (14)
The general procedure was followed as in Section 4.4
using ferrocenecarboxaldehyde (200 mg, 0.93 mmol) and
4-chlorophenylacetonitrile (141 mg, 0.93 mmol). An initial
yellow melt was obtained and on mixing with 2 drops of
piperidine, it turned into a red solution. The product was
isolated as a red solid which was further subjected to col-
umn chromatography using hexane/diethyl ether (5:1) as
the eluting solvent to achieve red crystals (287 mg, 89%);
m.p. 133 ꢁC; IR (KBr, cmꢀ1) 3094, 3033, 2208, 1644,
1597, 1492, 1458, 1408, 1363, 1271, 1252, 1184, 1096,
1
1053, 1040, 1001, 923, 836, 821, 545, 504, 481, 434; H
NMR (CDCl3) 7.72 (4H, s, ArH), 7.55 (1H, s, CH), 5.03
(2H, t, J 1.7, C5H4), 4.65 (2H, t, J 1.7, C5H4), 4.28 (5H,
s, C5H5); 13C NMR (CDCl3) 147.04, 139.49, 133.26,
125.84, 119.01, 118.77, 111.70, 104.86, 77.64, 72.98,
71.07, 70.51; m/z (EI), 339 (M++1, 10%), 338 (M+, 44%),
273 (8), 246 (8) 215 (7), 190 (24), 121 (31), 56 (11), 32
(19), 28 (100). Anal. Calc. for C20H14FeN2: C, 71.0; H,
4.2; N, 8.3; [M+], 338.050638. Found: C, 70.8; H, 4.2; N,
7.9%; [M+], 338.050578.
1
1052, 999, 923, 898, 827, 505, 482, 424; H NMR (CDCl3)
7.55 (2H, d, J 8.6, ArH), 7.41 (1H, s, CH), 7.38 (2H, s,
ArH), 4.99 (2H, t, J 1.7, C5H4), 4.58 (2H, t, J 1.7, C5H4),
4.26 (5H, s, C5H5); 13C NMR (CDCl3) 144.20, 134.45,
133.66, 129.62, 126.74, 119.25, 105.82, 77.55, 72.22,
70.64, 70.32; m/z (EI) 350 (M++3, 22%), 349 (M++2,
73), 347 (M+, 100), 282 (41), 257 (13), 255 (39), 199 (16),
191 (14), 190 (35), 165 (17), 164 (25), 163 (28), 121 (31),
56 (18), 45 (17), 44 (13), 28 (11). Anal. Calc. for
C19H14ClFeN: C, 65.7; H, 4.1; N, 4.0; [M+], 347.016417.
Found: C, 66.1; H, 4.3; N, 3.8%; [M+], 347.016398.
4.4.5. 3-Ferrocenyl-2-[4-
(trifluoromethyl)phenyl]acrylonitrile (17)
The general procedure was followed as in Section 4.4
using ferrocenecarboxaldehyde (200 mg, 0.93 mmol) and
4-(trifluoromethyl)phenylacetonitrile (172 mg, 0.93 mmol).
An orange/red paste was obtained on grinding. The prod-
uct was isolated as a red solid which was further subjected
to column chromatography using hexane/diethyl ether
(5:1) as the eluting solvent to achieve dark red crystals
(331 mg, 93%); m.p. 125 ꢁC; IR (KBr, cmꢀ1) 3056, 2936,
2217, 1615, 1593, 1454, 1417, 1334, 1251, 1169, 1110,
1073, 1000, 837, 733, 617, 492; 1H NMR (CDCl3) 7.71
(4H, m, ArH), 7.51 (1H, s, CH), 5.02 (2H, t, J 1.8,
C5H4), 4.62 (2H, t, J 1.8, C5H4), 4.27 (5H, s, C5H5); 13C
NMR (CDCl3) 146.03, 138.55, 130.53, 130.10, 126.43,
125.67, 119.09, 105.36, 77.17, 72.60, 70.89, 70.41; m/z
(EI) 382 (M++1, 9%), 381 (M+, 38%), 240 (6), 191 (9),
190 (13), 121 (10), 32 (19), 28 (100). Anal. Calc. for
C20H14F3FeN: C, 63.0; H, 3.7; N, 3.7; [M+], 381.042774.
Found: C, 62.9; H, 3.7; N, 3.5%; [M+], 381.042792.
4.4.3. 3-Ferrocenyl-2-(4-fluorophenyl)acrylonitrile (15)
The general procedure was followed as in Section 4.4
using ferrocenecarboxaldehyde (200 mg, 0.93 mmol) and
4-fluorophenylacetonitrile (126 mg, 0.93 mmol). An initial
yellow paste was obtained on grinding with piperidine
and this eventually turned red. The product was isolated
as a red solid which was further subjected to column chro-
matography using hexane/diethyl ether (5:1) as the eluting
solvent to achieve red crystals (281 mg, 91%); m.p. 95–
96 ꢁC; IR (KBr, cmꢀ1) 3054, 2921, 2851, 2214, 1602,
1590, 1511, 1454, 1415, 1366, 1308, 1279, 1251, 1233,
1164, 1105, 923, 831, 722, 614, 595, 494, 450, 431, 331;
1H NMR (CDCl3) 7.59 (2H, dd, Jbc 8.9, JbF 5.1, ArH),
7.33 (1H, s, CH), 7.12 (2H, t, JCbF 8.6, ArH), 4.97 (2H,
t, J 1.9, C5H4), 4.56 (2H, t, J 1.9, C5H4), 4.26 (5H, s,
C5H5); 13C NMR (CDCl3) 162.99 (1C, d, JCaF 248.9, Ca),
4.4.6. 3-Ferrocenyl-2-(4-nitrophenyl)acrylonitrile (18)
The general procedure was followed as in Section 4.4
using ferrocenecarboxaldehyde (200 mg, 0.93 mmol) and
4-nitrophenylacetonitrile (151 mg, 0.93 mmol). Upon addi-
tion of two drops of piperidine the solid mixture changed
rapidly into a purple melt. The product was isolated as a

3452
C. Imrie et al. / Journal of Organometallic Chemistry 692 (2007) 3443–3453
dark purple solid. The product was further subjected to
column chromatography using hexane/diethyl ether (4:1)
as the eluting solvent to achieve purple crystals (331 mg,
99%); m.p. 195 ꢁC; IR (KBr, cmꢀ1) 3094, 3054, 2219,
1603, 1582, 1514, 1457, 1372, 1340, 1254, 1199, 1113,
R1obs = 0.0389, wR2obs = 0.0898, R1all = 0.0790, wR2all =
0.1001, goodness-of-fit = 0.920.
Acknowledgements
1
The authors thank the following persons for technical
assistance: Mr. H. Marchand (UPE, now known as
NMMU) for general technical assistance, Dr. P. Boshoff
(formerly of the Cape Technikon, Cape Town) and Dr.
L. Fourie (Potchefstroom University, now called Univer-
sity of the North West) for their mass spectroscopic analy-
ses, and Mr. P. Benincasa (UCT) for elemental analyses.
The authors thank the University of Port Elizabeth
(NMMU) and the National Research Foundation (Preto-
ria) for funding.
1050, 1032, 1002, 849, 825, 753, 690; H NMR (CDCl3)
8.29 (2H, d, J 8.9, ArH), 7.77 (2H, d, J, 8.9, ArH), 7.61
(1H, s, CH), 5.05 (2H, t, J 1.8, C5H4), 4.68 (2H, t, J 1.8,
C5H4), 4.29 (5H, s, C5H5); 13C NMR (CDCl3) 147.87,
147.31, 141.35, 125.89, 124.87, 118.77, 104.41, 76.90,
73.21, 71.21, 70.59; m/z (EI) 359 (M++1, 12%), 358 (M+,
55%), 312 (7), 191 (6), 190 (12), 165 (6), 121 (25), 56 (6),
32 (19), 28 (100). Anal. Calc. for C19H14FeN2O2: C, 63.7;
H, 3.9; N, 7.8; [M+], 358.040467. Found: C, 64.2; H, 4.3;
N, 7.5%; [M+], 358.040422.
Appendix A. Supplementary material
5. X-ray crystallography
CCDC 286626 and 286627 contain the supplementary
crystallographic data for 16 and 17. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2007.04.011.
5.1. Structural analysis of 3-ferrocenyl-2-(4-cyanophenyl)-
acrylonitrile (16)
X-ray diffraction data for 16 and 17 were collected on
a Bruker SMART 1K CCD area detector diffractometer
with graphite-monochromated Mo Ka radiation (50 kV,
30 mA). The collection method involved x-scan of width
0.3ꢁ. Data reduction was carried out using the program
SAINT+, Version 6.02 [18]. Multi-scan absorption correc-
tions were made using the program SADABS [19]. The
crystal structures were solved by direct methods using
SHELXS-97 [20]. Non-hydrogen atoms were first refined
isotropically followed by anisotropic refinement by full-
matrix least-squares calculation based on F2 using
SHELXL-97 [20]. Hydrogen atoms were first located in
the different map then positioned geometrically and
allowed to ride on their respective parent atoms. Dia-
grams and publication materials were generated using
SHELXTL, PLATON [21] and ORTEP3 [22]. The general-pur-
pose crystallographic tool PLATON was used for structure
analysis.
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