Synthesis, characterisation and properties of ferrocenylalkylimidazolium salts

Article abstract of DOI:10.1016/j.jorganchem.2010.01.019

New ferrocenylalkylimidazolium salts [Fc(CH₂)_n(C₃H₃N₂)R]X^- were synthesised through the incorporation of green chemistry principles of atom economy and when feasible under solvent-free conditions. The products comprise a series of salts all characterised by the ferrocenyl moiety with variations in the length of the linker alkyl chain (n), the size of the imidazolium alkyl substituent (R) or the electronic nature of the counter-ion (X^-). The dependence of the physical and electronic properties of the salts on the three main structural variants was studied. It was found that variation in the steric size of the R group has the most profound influence on the melting points of the ionic liquids. The compounds were fully characterised by IR, ¹H and ¹³C NMR, MS and melting point determinations.

Full text of DOI:10.1016/j.jorganchem.2010.01.019

Journal of Organometallic Chemistry 695 (2010) 1126–1132
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, characterisation and properties of ferrocenylalkylimidazolium salts
*
*
Vincent O. Nyamori , Mhleli Gumede, Muhammad D. Bala
School of Chemistry, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa
a r t i c l e i n f o
a b s t r a c t
ꢀ
Article history:
2 n 3 3 2
New ferrocenylalkylimidazolium salts [Fc(CH ) (C H N )R]X were synthesised through the incorpora-
Received 15 December 2009
Received in revised form 7 January 2010
Accepted 14 January 2010
Available online 21 January 2010
tion of green chemistry principles of atom economy and when feasible under solvent-free conditions.
The products comprise a series of salts all characterised by the ferrocenyl moiety with variations in
the length of the linker alkyl chain (n), the size of the imidazolium alkyl substituent (R) or the electronic
ꢀ
nature of the counter-ion (X ). The dependence of the physical and electronic properties of the salts on
the three main structural variants was studied. It was found that variation in the steric size of the R group
Keywords:
has the most profound influence on the melting points of the ionic liquids. The compounds were fully
Ferrocenylalkylimidazole
Ferrocenylalkylimidazolium salts
Green chemistry
1
13
characterised by IR, H and C NMR, MS and melting point determinations.
Ó 2010 Elsevier B.V. All rights reserved.
Solventless synthesis
Ionic liquid
1
. Introduction
synthesis and study of the reactivity, but also the isolation and full
characterisation of the first nucleophilic NHC (Fig. 1). It is, how-
ever, noteworthy that the ferrocenyl moiety containing analogues
of the NHCs has received less attention, with the exception of the
work by Snegur et al. [8] with a series of N-heterocyclic groups
linked to ferrocenyl compounds such as ferrocenylmethylbenzim-
idazole which were found to exhibit anticancer activity. The
importance of related compounds is again highlighted by Howarth
The study of substituted imidazolium-based salts has been an
active area of research due to the wide variety of applications that
utilizes their unique physical and chemical properties [1]. Specifi-
cally, they have been used as ionic liquids [2] and as ancillary li-
gands in catalysis [3]. Relevant to the current study is the
tethering of ferrocene to an imidazolium ion which extends the
chemical diversity of intrinsically electroactive ionic liquid phases
to redox molten salts [4]. This also diversifies the class of stable N-
heterocyclic carbene (NHC) ligands especially as sources of carb-
enes containing redox-active ferrocenyl substituents [5].
The ferrocenyl moiety represents a quite bulky group with un-
ique spatial requirements due to its sandwich shape, and electron-
ically, the powerful donor capacity of ferrocene is important in the
stabilization of highly reactive metal centres and other electroac-
tive species. Some of the important properties that ferrocenyl con-
taining imidazolium salts exhibit that makes their study significant
include electronic stabilisation of adjacent electron-deficient cen-
tres due to participation of the iron atom in the dispersal of the po-
sitive charge; the unique steric bulk, chemical stability and
reversibility of the ferrocene/ferrocenium redox couple [6]. In re-
cent years, aryl and alkyl imidazolium compounds have been the
subject of intense scientific study including the topical work by
Arduengo et al. [7] who demonstrated the stabilisation of carbenes
with a variety of substituents that allows not only for the in situ
0
and Hanlon [9] through the synthesis of N-ferrocenylmethyl-N -
methyl-2-substituted benzimidazolium iodide salts which are ac-
tive against the malaria parasite, P. falciparum. Later, Bildstein
[10] highlighted the stereoelectronic influence of the ferrocenyl
group on carbenes in terms of steric protection, electron-donation
and reversible redox chemistry that makes them interesting com-
pounds for a variety of applications. However, in his findings, he
suggests that the ferrocenyl group has no capability of electroni-
cally stabilising NHCs.
Another important aspect of this study is the application of
green chemistry principles to synthesis. Especially relevant is the
exclusion of solvents whenever possible by applying solvent-free
synthetic techniques which have been shown to give higher yields
and selectivities as compared to the same reaction carried out in
the presence of organic solvents [11]. Hence, the methods of Ranu
et al. [12] has been adopted and modified in this study. Therefore,
in this report we present work on the synthesis and characterisa-
tion of new ferrocenylalkylimidazoles and ferrocenylalkylimidazo-
lium salts with the aim of studying the effects of structural
variations on the physical and electronic properties of the salts,
since the ability to tune their structural and electronic properties
has implications on their applications in catalysis [13] and as envi-
ronmentally green ionic liquid solvents.
*
Corresponding authors. Tel.: +27 31 260 8256; fax: +27 31 260 3091.
E-mail addresses: nyamori@ukzn.ac.za (V.O. Nyamori), bala@ukzn.ac.za (M.D.
Bala).
0
022-328X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.01.019

V.O. Nyamori et al. / Journal of Organometallic Chemistry 695 (2010) 1126–1132
1127
described by Ranu et al. [12], however, attempts to follow the sug-
gested method led to lower yields and significant amount of
decomposition. Hence, we slightly modified the described proce-
dure by cooling the reaction mixture (ꢁ15 °C). This was achieved
by having the reaction flask with the exothermic mixture initially
kept in a temperature controlled cool water bath with occasional
shaking and cooling in an ice bath for about 30 min to obtain a pink
coloured solid mass. This was then placed on a shaker at room tem-
perature under vacuum and vigorously shaken for 36 h to ensure
maximum homogeneity of the mixture and minimal decomposi-
tion of the product. The above method for the acylation of ferro-
cene has a significant advantage over existing methods in that it
avoids the synthesis of acyl chlorides as a separate step and the
handling of aluminium trichloride, a corrosive and sensitive re-
agent was also avoided. Moreover, the methodology provides a di-
rect use of carboxylic acids, operational simplicity and excellent
selectivity (only monoacylation occurs), and thus it offers signifi-
cant improvements over other procedures involving Friedel–Crafts
acylation of ferrocenes [16].
N
N
R , R or both = ferrocenyl moiety
1 2
R1
R
2
Fig. 1. General structure of ferrocenylalkylimidazolium carbenes.
2
. Results and discussion
All the series of ferrocenylalkylimidazolium salts reported here
were synthesised by using ferrocenylalkylimidazoles as precursors,
which were synthesised via two routes. In the first method, ferr-
ocenylcarbinols were first synthesised from the reduction of ferro-
cene monocarboxyaldehyde. The second step involved synthesis of
ferrocenylalkylimidazoles (Scheme 1) from a reaction of equimolar
amounts of ferrocenylcarbinols and N,N -carbonyldiimidazole in
anhydrous dichloromethane. Attempts to perform this reaction
under solvent-free conditions were unsuccessful even though a
0
0
similar reaction with the sulfur analogue, N,N -thiocarbonyldiimi-
The second step involved the reduction of the ferrocenylalkyl
ketone (Scheme 2b) by using equimolar quantities of aluminium
trichloride and tert-butylamine-borane in dry diethyl ether under
a nitrogen atmosphere at room temperature. This reaction proved
to be very efficient, providing yields in excess of 92%. The third step
dazole, has been reported [14]. The reaction mixture was refluxed
for 1 h followed by a work-up procedure and then chromato-
graphic isolation of the products as reported by Simenel et al.
15] was performed.
In the second method, ferrocenylalkyl bromides were first syn-
[
(Scheme 2c) also occurred under mild conditions with the use of
thesised as precursors for the synthesis of ferrocenylalkylimidaz-
oles through selective monoacylation of ferrocene. This was
achieved by using a greener approach (as opposed to the common
conditions and reagents for a Friedel–Crafts acylation reaction)
involving the reaction between bromoalkylcarboxylic acid and tri-
fluoroacetic anhydride with ferrocene on activated alumina under
solvent-free conditions (Scheme 2a). A similar reaction has been
equimolar amounts of the ferrocenylalkyl bromide and the imidaz-
ole in the presence of a base, KOH powder. The ferrocenylalkylim-
idazole product was isolated fairly easily and yields were good.
The synthesis of ferrocenylalkylimidazolium salts was achieved
firstly by quaternization of the ferrocenylalkylimidazoles 1 and 2
to form the corresponding desired cations and anions (Scheme 3).
This was achieved by using an alkyl iodide or bromide compound
O
H
H
N
N
C
H
N
C
H
OH
N
N
(a)
N
Fe
Fe
CH Cl , 1 hour Reflux
2
2
1
Scheme 1. Synthesis of ferrocenylalkylimidazole via a ferrocenylmethanol route.
O
O
C
Al O
2
3
(a)
+
Br-(CH2)5
C
Fe
Fe
(CH2)5 Br
OH
(
CF CO) O
3 2
solvent-free
O
AlCl , [CH3(CH2)3]4N-BF3
3
(CH2)6 Br
(b)
C
Fe
(CH2)5 Br
Fe
diethyl ether, room temp.
(
CH2)6 Br
KOH, Acetone
Stir, room temp.
(CH2)6
N
N
HN
N
(
c)
Fe
+
Fe
2
Scheme 2. Synthesis of ferrocenylalkylimidazole via a ferrocenylalkyl bromide route.

1
128
V.O. Nyamori et al. / Journal of Organometallic Chemistry 695 (2010) 1126–1132
as the alkylating reagent. This yielded the primary halide salts
compounds 3–8, Table 1). Secondly, a metathesis reaction was
carried out that involved anion exchange using compounds such
as sodium tetrafluoroborate, sodium hexafluorophosphate and so-
dium hexafluoroantimonate with the aim of introducing a variety
of counter anions.
ration, since the size of its cation is unusually larger than its anion
as compared with those of the halide salts 3–7. The change in the
length of the alkyl ferrocenyl-imidazolium linker from n = 1 to
n = 6 whilst keeping the other variables constant, also had a similar
but less drastic effect on the melting point in that the longer chain
(n = 6) salts have lower meting points. This may be observed by
comparing salts 3 vs. 6, 4 vs. 7, 5 vs. 8, 9 vs. 12, 10 vs. 13 and
11 vs. 14 with the larger anions being anomalies (i.e. salts 15 vs.
18 and 19 vs. 22).
As indicated earlier the halide salts were further investigated by
carrying out anion exchange reactions to provide other ferro-
cenylalkylimidazolium salts which are used to further probe the
effect of the counter anion. This was achieved by the metathesis
reactions shown in Scheme 4.
It is interesting to note again the effect of changing the counter-
ion on the physical properties of the salts. An example is the
change from the solid-state in compound 5, to pastes in com-
pounds 11 and 17 and subsequently to a liquid oil in compound
21. This phenomenon correlates with previous observation where-
by an increase in the size of the counter-ion introduces increased
asymmetry which usually leads to a decrease in the melting points
of salts [17]. A larger counter anion will also cause a reduction in
the melting point of a salt as a result of the disruption in the crystal
packing and a reduction of the crystal lattice energy. Moreover, a
gradual increase in the size of the anion while keeping the same
cation reduces the Coulombic attraction between the two ions in
addition to the fact that larger ions enable charge delocalization,
further reducing the overall charge density and hence causing a de-
crease in melting point.
(
The ferrocenylalkylimidazolium halide salts 3–7 were found to
be solids at room temperature while 8 was a liquid oil. If the alkyl
linker chain length is kept constant (i.e. n = 1 or 6), then the trend
observed for a series of salts is that the melting points decrease
with an increase in the molecular size of the imidazolium alkyl side
chain R on the imidazole moiety in the order methyl > n-butyl > n-
octyl. Compound 8 was a liquid oil due to a combination of a long
alkyl linker (hexyl) and an equally long octyl imidazole side chain.
The two long alkyl derivatives combine to exert strain on the
molecular chain of 8 and affect its ability to pack in any ordered
fashion that will result in solidification. This poor crystal packing
causes a lowering of the melting point and is a general observation
for all the series studied. The melting points of the salts studies are
affected by a combination of the properties of the constituent an-
ions and cations. It is interesting to note that the results correlate
with what is known for ionic liquid anion–cation combinations
[
17]. In addition, the oily compound 8 is expected to have the
weakest inter-ion Coulombic attraction due to a larger ionic sepa-
Table 1
The effects of molecular structural variations on the properties of ferrocenylalkylim-
idazolium salts.
Compounda
ꢀ
b
1H NMR (ppm)c
In addition to the observation of changes in melting point, the
effect of varying the structural features of the salts was also mon-
itored on the electronic environment around the imidazolium ion.
To understand this, in Table 1 we tracked the chemical shifts of the
imidazolium C-1 protons of the primary halide salts and the deriv-
n
–R
X
mp (°C)
1
2
3
4
5
6
7
8
9
1
6
1
1
1
6
6
6
1
1
1
6
6
6
1
1
1
6
1
1
1
6
None
None
–CH
–(CH
–(CH
–CH
–(CH
–(CH
–CH
–(CH
–(CH
–CH
–(CH
–(CH
–CH
–(CH
–(CH
–CH
–CH
–(CH
–(CH
–CH
None
None
66–67
68–70
7.50
7.47
10.13
10.58
10.69
10.08
10.79
10.76
8.91
9.19
9.17
9.94
8.96
9.17
9.05
8.62
8.61
9.18
9.94
8.44
8.44
9.58
3
I
130–135
85
2
)
)
3
CH
CH
3
Br
Br
I
2
7
3
71
95
75
Oil
145
73
Paste
91
Oil
Oil
66–68
70
Paste
93
66
52
1
atives that were obtained via metathesis. The H NMR analysis of
3
the ferrocenylalkylimidazolium salts show that there is a consider-
able deshielding effect by the various anions on the imidazolium
protons. This is evident from the significant shift to a lower reso-
nance experienced by the imidazolium salts protons relative to
2
2
)
)
3
CH
CH
3
Br
7
3
Br
BF
BF
BF
BF
BF
BF
PF
ꢀ
3
4
ꢀ
1
1
1
1
1
1
1
1
1
1
2
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
2
2
)
)
3
CH
CH
3
4
ꢀ
7
3
4
those of the neutral ferrocenylalkylimidazole compounds
1
ꢀ
3
4
ꢀ
(7.50 ppm) and 2 (7.47 ppm). For instance, this is illustrated by
2
)
)
3
CH
CH
3
4
1
ꢀ
comparing the H NMR spectrum of compound 2 with that of its
2
7
3
4
ꢀ
3
6
derivative salt compound 6 (see also Fig. 2.1 and Tables 2.1–2.5
of the Supplementary material). Generally, the deshielding effect
is more pronounced by the halide salts compared to other anions.
The size of the anion and its effective charge influence the electro-
static interaction on the imidazolium protons, hence different
chemical shifts are observed. The size of the anions increases in
ꢀ
2
2
)
)
3
CH
CH
3
PF
PF
PF
6
ꢀ
7
3
6
ꢀ
3
6
ꢀ
3
SbF
SbF
SbF
SbF
6
ꢀ
2
)
)
3
CH
CH
3
6
ꢀ
2
7
3
6
Oil
68
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
3
6
the order Br < I < BF < PF < SbF , however, the effective charge
4 6 6
a
b
c
is highest on Br . Hence, the NMR chemical shift on the imidazoli-
um protons of salts 3 to 8 are relatively shifted down field com-
pared to all the analogues derived from them through anion
See Section 4.
Some compounds are oils or pastes at RT.
Chemical shifts of imidazole H
3
2
1
Proton (CDCl
3
).
N
N
1
X-
+
N
N
N
N
RX
(
CH )n
R
2
(
CH )n
Fe
2
Fe
Reflux, N , 12 hours
2
n = 1 or 6
X = I or Br
R = CH , (CH ) CH , or (CH ) CH
3
3
2 3
3
2 7
Scheme 3. Synthesis of ferrocenylalkylimidazolium halide salts.

V.O. Nyamori et al. / Journal of Organometallic Chemistry 695 (2010) 1126–1132
1129
-
N+Y
X-
N
NaY, Acetone
N , RT., 24 hours
+
N
N
(CH )n
R
2
Fe
(
CH )n
R
2
2
Fe
-
-
-
X = I or Br
n = 1 or 6
-
-,
PF6-, or SbF6-
Y = BF
4
R = CH , (CH ) CH , or (CH ) CH
3
2 3
3
2 7
3
Scheme 4. Anion exchange reaction on ferrocenylalkylimidazolium halide salts
metathesis. The relatively higher charge density seen on the halide
anions also contributes to their relatively higher melting points
compared with their salt analogues. Solid-state X-ray crystallogra-
(Scheme 2c), imidazole (148 mg, 2.17 mmol) was added to acetone
(2.0 cm ) and the solution was stirred. Potassium hydroxide pow-
3
der (128 mg, 2.27 mmol) was then introduced and allowed to dis-
solve, forming a homogenous solution. The solution was stirred for
about 30 min and then 6-bromohexylferrocene (834 mg,
1
phy and H NMR evidence suggests that the halides can enter into
hydrogen bonding with cationic centres [18]. This bonding has
been postulated to be between the electron-deficient C-2 carbon
atom of the imidazolium ring and the halides.
3
2.39 mmol) in acetone (1.0 cm ) was introduced to the solution
dropwise and allowed to stir for about 1 h at room temperature.
The solution was then filtered and concentrated. The crude product
was passed through a column of silica gel. Diethyl ether recovered
unreacted 6-bromohexylferrocene (150 mg) while ethyl acetate/
methanol (10:1) afforded the product 2 as yellow crystals
3
. Conclusions
The synthesis of a series of ferrocenylalkylimidazolium salts has
ꢀ1
(
591 mg, 81%); mp 68–70 °C; IR (KBr cm ) 3090, 2932, 2859,
been achieved. In some steps the green chemistry concept of sol-
ventless reactions and atom economy was applied by the use of
equimolar amounts of neat reagents without the use of potentially
harmful organic solvents. Generally, the salts generated via the sol-
ventless technique were obtained in higher yields as compared to
procedures utilizing solvents. The key structure-dependent prop-
erty of the salts was investigated by determining their melting
temperatures. Salts that structurally contain bulkier cations or an-
ions have relatively lower melting points compared with those
consisting of sterically smaller ionic components. This is postu-
lated to be due to weaker intermolecular forces of interaction
and a poorer ability for ordered crystal packing. The electronic nat-
ure of the various anions has been shown to influence the chemical
shifts of the imidazolium protons with the halide anions showing
the largest influence.
1
6
655, 1508, 1466, 1439, 1234, 1107, 1076, 999, 829, 802, 745,
71, 509, 486; H NMR (CDCl ) 7.47 (1H, s, NCH), 7.07 (1H, s,
3
1
NCH), 6.91 (1H, s, NCH), 4.09 (5H, s, C
5
H
5
), 4.04 (4H, m, C
), 2.31 (2H, t, J 7.3, CH ), 1.77 (2H, m, CH
), 1.31 (4H, m, 2 ꢂ CH
37.48, 129.76, 119.22, 89.45, 68.87, 68.45, 67.48, 47.42, 31.44,
5
H
4
),
),
3
1
1
3
6
.91 (2H, t, J 7.1, CH
2
2
2
1
3
.48 (2H, m, CH
2
2
);
3
C NMR (CDCl )
+
+
1.37, 29.89, 29.35, 26.83; m/z (EI) 337 (M +1, 14%), 336 (M ,
1%), 272 (19), 271 (100), 269 (10), 199 (9), 121 (26); Anal. Calc.
+
for C19
H
24
N
2
Fe: C, 67.8; H, 7.2; N, 8.3; [M ], 336.128888. Found:
+
C, 67.5; H, 7.3; N, 8.0%; [M ], 336.128905.
4.2. Synthesis of ferrocenylalkylimidazolium halide salts
The ferrocenylalkyl imidazolium halide (Br and I) salts were all
synthesised following a similar procedure. A typical method is de-
scribed for 1-(ferrocenylmethyl)-3-methylimidazolium iodide 3.
4
. Experimental
4.1. General
4.2.1. 1-(Ferrocenylmethyl)-3-methylimidazolium iodide 3
In a two-neck round-bottom flask, methyl iodide (4 mL, 9.12 g,
64.26 mmol) was added to ferrocenylmethyl imidazole (1.0098 g,
3.7944 mmol) and allowed to reflux gently for ꢁ15 h at 50 °C un-
der an atmosphere of nitrogen. The solution was then allowed to
cool to room temperature before it was washed with anhydrous
diethyl ether several times to yield a yellow solid. The crude prod-
uct was dissolved in dichloromethane and recrystallized in hexane
to yield yellow crystals of 3 (1.07 g, 70%), mp 130–135 °C; IR
All reactions involving air and moisture sensitive compounds
were carried out under a nitrogen atmosphere using standard
Schlenk techniques. Solvents were dried by using standard meth-
ods under a nitrogen atmosphere. Melting points were recorded
with a Stuart Scientific Melting Point apparatus SMP3 in duplicate
and the readings were averaged. Infrared spectra were recorded
with a Perkin Elmer Universal ATR (Spectrum 100) FT-IR spec-
trometer. All NMR experiments were conducted in deuterated
chloroform with a 400 MHz Bruker Advance 3 spectrometer. Mass
spectra were recorded on a VG70-SEQ/MSSMS2 spectrometer at
the Cape Technikon or the Waters LCT Premier TOF (time of
flight) MS using direct infusion at the University of KwaZulu-
Natal.
ꢀ1
(cm ) 3434, 3042, 1567, 1549, 1428, 1150, 1040, 837, 821, 755,
1
6
20, 502, 482; H NMR (CDCl
2 ꢂ NCH), 5.33 (2H, s, CH ), 4.43 (2H, t, J 1.8, C
.8, C ), 4.25 (5H, s, C ), 4.01 (3H, s, CH
(3%), 198.5 (100%), 199.2 (15%), 280.6 (M - I , 7.4%); Anal. Calc.
3
) 10.13 (1H, s, NCH), 7.09 (2H, m,
), 4.26 (2H, t, J
); m/z (ESI) 197.1
2
5 4
H
1
H
5 4
5
H
5
3
+
ꢀ
+
+
for C15
H
17
N
2
Fe ; [M ]ꢀI, 281.07411.
All chemicals used for synthesis were commercially available
and were used as received. Ferrocenylalkylimidazole precursors
were synthesised by adaptation of literature procedures. The first
precursor 1-(ferrocenylmethyl)-1H-imidazole 1 was obtained from
ferrocenylmethanol by the method of Simenel et al. [15]. The sec-
ond precursor 1-(6-ferrocenylhexyl)-1H-imidazole 2 was obtained
through a three-step synthetic procedure. The first step (Scheme
4.2.2. 1-(Ferrocenylmethyl)-3-butylimidazolium bromide 4
This salt was synthesised following a similar method to 3 using
butyl bromide (10 mL) to yield 1.48 g, 97% of 4; mp 85 °C; IR (ATR
ꢀ1
cm ) 3404, 3065, 2958, 1625, 1558, 1464, 1238, 1150, 1105, 1000,
1
816, 773, 624, 480; H NMR (CDCl
m, 2 ꢂ NCH), 5.31 (2H, s, NCH ), 4.42 (2H, s, CH
, C ), 4.24 (2H, m, C ), 1.87 (2H, m, CH
2 ꢂ CH ), 0.95 (3H, m, CH ); m/z (ESI) 124.9 (0.9%), 181.1 (22%),
3
) 10.58 (1H, s, NCH), 7.06 (2H,
), 4.26 (7H, s,
), 1.36 (4H, m,
2
2
2a) was an adaptation from Ranu et al. [12], while the second step
C H
5 5
5
H
4
5
H
4
2
(Scheme 2b) was adapted from Lau et al. [19]. In the final step
2
3

1
130
V.O. Nyamori et al. / Journal of Organometallic Chemistry 695 (2010) 1126–1132
+
ꢀ
1
3
96.9 (3%), 198.6 (100%), 199.4 (15%), 322.8 (M ꢀBr ), 323.7 (7%),
4.3. Anion exchange on ferrocenylalkylimidazolium halide salts
+
23 2
78.9 (4%), 464.7 (6%), 724.8 (1%); Anal. Calc. for C18H N Fe ;
+
[
M ]ꢀBr, 323.12051.
All the ion exchange reactions were conducted following a sim-
ilar procedure. A typical method is described for the tetrafluorobo-
rate ion.
4
.2.3. 1-(Ferrocenylmethyl)-3-octylimidazolium bromide 5
This salt was synthesised following a similar method to 3
4
.3.1. 1-(Ferrocenylmethyl)-3-methylimidazolium tetrafluoroborate 9
In a two-neck round-bottom flask was added sodium tetrafluo-
using octyl bromide (12 mL) to yield 1.54 g, 94% of 5; mp 71 °C;
1
IR (ATR cm ) 3476, 3409, 3090, 2924, 2854, 1621, 1438, 1157,
roborate (0.08 g, 0.77 mmol) to a solution of 1-(ferrocenylmethyl)-
-methylimidazolium iodide (0.31 g, 0.75 mmol) in acetone
20 mL). The mixture was stirred under a nitrogen atmosphere
1
(
105, 999, 835, 814, 770, 734, 558, 481; 1H NMR (CDCl
3
) 10.69
), 4.42 (2H,
), 1.24 (14H, m, 7 ꢂ CH ), 0.84
3
3H, m, CH ); m/z (ESI) 181 (0.6%), 197 (3.4%), 198.7 (100%),
3
(
1H, s, NCH), 7.07 (2H, d, 2 ꢂ NCH), 5.36 (2H, s, CH
2
s, CH
2
), 4.24 (9H, m, C
5
H , C
5 5
H
4
2
for 24 h at room temperature. The reaction mixture was filtered
through a plug of celite and the filtrate was then concentrated in
vacuo to give 0.21 g, 76% of an orange powder 9 (mp 145 °C; IR
(
+
1
1
3
99.5 (14%), 265.8 (0.5%), 293.1 (4%), 377.2 (5%), 378.9 (M ꢀBr,
+ +
00%), 379.5 (23%); Anal. Calc. for
77.16801.
C
22
H
29
N
2
Fe ; [M ]ꢀBr,
ꢀ1
(
ATR cm ) 3436, 3069, 1559, 1323, 1152, 1104, 1039, 1000, 819,
1
7
72, 748, 618, 480; H NMR (CDCl
3
) 8.91 (1H, s, NCH), 7.08 (1H,
), 4.37 (2H, t, J 1.8,
), 4.27 (5H, s, C ), 3.91 (3H, s,
3
C NMR (CDCl ) 136.18, 123.08, 121.40, 78.35, 77.26,
s, NCH), 7.07 (1H, s, NCH), 5.18 (2H, s, CH
C
CH
2
4
.2.4. 1-(6-Ferrocenylhexyl)-3-methylimidazolium iodide 6
H
5 4
), 4.27 (2H, t, J 1.8, C
H
5 4
5 5
H
1
3
This salt was synthesised following a similar method to 3
3
);
3
using methyl iodide (3.0 cm , 6.84 g, 48.2 mmol) and compound
69.89, 69.68, 69.26, 50.11; m/z (ESI) 197.1 (3%), 198.6 (100%),
+
ꢀ
2
9
1
6
7
4
(5.00 g, 13.7 mmol) to yield yellow solid crystals of 6 (6.16 g,
199.2 (14%), 280.6 (M ꢀBF , 7.5%), 281.6 (1.1%). Anal. Calc. for
4
ꢀ1
+
+
4%), mp 95 °C; IR (KBr cm ) 3083, 2927, 2858, 1584, 1564,
C
H
15 17
N
2
Fe ; [M ]ꢀBF
4
, 281.07411.
471, 1433, 1374, 1257, 1174, 1103, 1040, 1000, 920, 808, 729,
53, 616, 512, 491, 419; 1H NMR (CDCl
), 10.08 (1H, s, NCH),
.43 (1H, s, NCH), 7.34 (1H, s, NCH,), 4.31 (2H, t, J 7.3, CH ),
.11 (3H, s, NCH ), 4.09 (5H, s, C ), 4.04 (4H, m, C ), 2.33
), 1.92 (2H, m, CH ), 1.47 (2H, m, CH ), 1.38
), 137.44, 123.86, 122.29,
4.3.2. 1-(Ferrocenylmethyl)-3-butylimidazole tetrafluoroborate 10
This salt was synthesised following a similar method to 9 using
sodium tetrafluoroborate (0.24 g, 2.15 mmol) and 1-(ferrocenylm-
ethyl)-3-butylimidazolium bromide (0.43 g, 1.08 mmol) to yield a
brown powder of 10 (0.33 g, 75%); mp 73 °C; IR (ATR cm
3
2
3
H
5 5
5 4
H
(
(
2H, t, J 7.5, CH
2
2
2
1
3
ꢀ1
4H, m, 2 ꢂ CH
2
);
C NMR (CDCl
3
)
8
2
1
5
3
9.37, 68.91, 68.51, 67.49, 50.66, 37.53, 31.33, 30.58, 29.88,
3147, 3094, 2961, 1561, 1466, 1152, 1035, 822, 752, 625, 499,
+
1
9.20, 26.54; m/z (FAB) 351 (M ꢀI, 100%), 199 (7), 154 (21),
481; H NMR (CDCl
5.23 (2H, s, CH ), 4.38 (2H, t, J 1.8, C
4.16 (5H, s, C ), 1.82 (2H, m, CH ), 1.33 (4H, m, CH
) 207, 136, 121, 77.24, 69.8, 69.5,
9.2, 50, 32, 19, 13; m/z (ESI) 124.9 (0.3%), 181.2 (12.1%), 182
3
) 9.1900 (1H, s, NCH), 7.1199 (2H, m, 2 ꢂ NCH),
), 4.24 (2H, t, J 1.8, C ),
), 0.93 (3H,
36 (20), 83 (12), Anal. Calc. for C20
H
27
N
2
FeI: C, 50.2; H, 5.7; N,
2
5
H
4
5 4
H
+
+
.9; [M ]ꢀI, 351.152363. Found: C, 50.1; H, 5.8; N, 5.8%; [M ]ꢀI,
5
H
5
2
2
1
3
51.152426.
3 3
t, J 7.2, CH ); C NMR (CDCl
6
(
(
1.2%), 197 (2.2%), 198.6 (100%), 199.3 (15%), 322.7 (27%), 323.7
4
.2.5. 1-(6-Ferrocenylhexyl)-3-butylimidazolium bromide 7
+
+
+
4 23 2
M ꢀBF , 5.4%); Anal. Calc. for C18H N Fe ; [M ] 323.12051.
This salt was synthesised following a similar method to 3
3
using n-bromobutane (5.0 cm , 6.38 g, 46.6 mmol) and compound
2
4
.3.3. 1-(Ferrocenylmethyl)-3-octylimidazolium tetrafluoroborate 11
This salt was synthesised following a similar method to 9 using
an excess of sodium tetrafluoroborate (0.52 g, 4.71 mmol) and 1-
ferrocenylmethyl)-3-octylimidazolium bromide (0.39 g,
.83 mmol) to yield an orange-yellow paste identified as 11
(5.00 g, 13.7 mmol) to yield 5.77 g, 89%, of brown powder of 7
ꢀ1
(
mp 75 °C; IR (KBr cm ) 3047, 2954, 2935, 2856, 1691, 1559,
1
6
2
C
465, 1377, 1329, 1167, 1105, 1021, 999, 922, 820, 754, 732,
(
0
(
1
58, 635, 614; H NMR (CDCl
ꢂ NCH), 4.37 (4H, m, 2 ꢂ CH
), 2.27 (2H, t, J 7.2, CH
), 1.38 (8H, m, 4 ꢂ CH
C NMR (CDCl ), 137.63, 122.33, 122.25, 89.36,
3
), 10.79 (1H, s, NCH), 7.25 (2H, s,
), 4.18 (5H, s, C ), 4.14 (4H, m,
), 0.99 (3H, t,
2
5 5
H
ꢀ1
0.38 g, 97%); IR (ATR cm ) 2927, 1561, 1014, 773, 550, 526,
H
5 4
2
2
1
4
(
83; H NMR (CDCl
1H, s, NCH), 5.22 (2H, s, CH
t, J 1.8, C ), 4.23 (5H, s, C
3
) 9.17 (1H, s, NCH), 7.09 (1H, s, NCH), 7.07
), 4.38 (2H, t, J 1.8, C ), 4.25 (2H,
), 4.14 (2H, m, CH ), 1.26 (12H, m,
2 3 3
), 0.85 (3H, m, CH ); C NMR (CDCl ) 135.9, 121.2, 121.1,
1
3
J 6.5, CH
6
2
3
);
3
2
5 4
H
8.88, 68.47, 67.47, 50.44, 50.24, 32.58, 31.35, 30.70, 29.86,
5
H
4
5
H
5
2
+
9.25, 26.54, 19.88, 13.90; m/z (FAB) 393 (M ꢀBr, 100%), 271
1
3
6
7
1
ꢂ CH
(
(
3
10), 199 (12), 179 (7), 165 (5), 151 (10), 138 12), 121 (11);
Found: [M ]ꢀBr, 393.199288. C23
7.2, 69.9, 69.5, 69.3, 50.3, 50.0, 31.6, 30.1, 29, 28.8, 26.2, 22.6,
+
+
H
33
N
2
FeBr requires [M ]ꢀBr,
4.0; m/z (ESI) 197.1 (2.9%), 198.6 (100%), 199.4 (12%), 377.2
93.199314).
ꢀ
+
(
2.8%), 378.9 (M ꢀBF , 59%), 379.7 (14%), 380.8 (2.6%); Anal. Calc.
4
+
+
for C22
H
29
N
2
Fe ; [M ]ꢀBF
4
, 377.16801.
4
.2.6. 1-(6-Ferrocenylhexyl)-3-octylimidazolium bromide 8
This salt was synthesised following a similar method to 3 using
n-bromooctane (5.0 cm , 5.59 g, 29.0 mmol) and compound 2
4.3.4. 1-(6-Ferrocenylhexyl)-3-methylimidazolium tetrafluoroborate
12
3
(
5.00 g, 13.7 mmol) to yield 6.24 g, 86% of brown oil 8; IR (CHCl
3
This salt was synthesised following a similar method to 9 using
sodium tetrafluoroborate (0.46 g, 4.18 mmol) and 1-(6-ferro-
cenylhexyl)-3-methylimidazolium iodide (2.00 g, 4.18 mmol) to
give a yellow solid identified as 12 (1.79 g, 98%); mp 91 °C; IR
ꢀ
1
cm ) 3022, 2935, 2860, 1584, 1559, 1468, 1238, 1223, 1162,
1
7
C
2
104, 1001, 821, 693, 485; 1H NMR (CDCl
.28 (2H, m, 2 ꢂ NCH), 4.37 (5H, s, C ), 4.17 (8H, m, 2 ꢂ CH
), 2.29 (2H, m, CH ), 1.70 (4H, m,
), 1.97 (4H, m, 2 ꢂ CH
ꢂ CH ), 1.33 (12H, m, 6 ꢂ CH ), 0.89 (3H, t, J 7.2, CH
), 137.63, 122.33, 122.25, 89.36, 68.88, 68.47, 67.47, 50.24,
3
), 10.76 (1H, s, NCH),
H
5 5
2
,
ꢀ1
H
5 4
2
2
(KBr cm ) 3088, 2928, 2860, 1636, 1584, 1564, 1471, 1375,
1
3
1
2
2
3
); C NMR
1312, 1258, 1174, 1103, 1084, 1041, 1000, 808, 730, 653, 616; H
(
CDCl
3
NMR (CDCl
t, J 1.7, NCH), 4.29 (2H, t, J 7.4, CH
s, C ), 4.03 (4H, m, C ), 2.30 (2H, t, J 7.5, CH
CH ), 1.47 (2H, m, CH
), 1.35 (4H, m, 2 ꢂ CH
137.10, 124.10, 122.53, 89.41, 68.92, 68.50, 67.49, 50.59, 37.52,
3
) 9.94 (1H, s, NCH), 7.51 (1H, t, J 1.7, NCH), 7.41 (1H,
), 4.09 (3H, s, NCH ), 4.08 (5H,
), 1.89 (2H, m,
3
4
2
1
2.58, 31.35, 30.70, 29.86, 29.25, 26.54, 19.88, 13.90; m/z (FAB)
2
3
+
49 (M ꢀBr, 100%), 403 (7), 328 (8), 293 (5), 271 (20), 249 (11),
5
H
5
H
5 4
2
3
1
35 (11), 221 (11), 199 (28), 181 (9), 151 (7), 135 (10), 121 (40),
2
2
2 3
); C NMR (CDCl )
+
08 (18); (Found: [M ]ꢀBr, 449.261993. C27
41 2 4
H N FeBF requires
+
+
[
M ]ꢀBr, 449.261914).
31.40, 30.61, 29.86, 29.86, 29.23, 26.52; m/z (FAB) 351 (M ꢀBF
4
,

V.O. Nyamori et al. / Journal of Organometallic Chemistry 695 (2010) 1126–1132
1131
+
ꢀ
1
00%), 200 (11), 154 (6), 137 (10), 121 (10), 121 (10), 109 (10);
198.6 (100%), 199.3 (13.3%), 241.9 (4%), 322.8 (M ꢀPF , 12.7%),
6
+
+
+
(
[
Found: [M ]ꢀBF
4
,
351.152401.
C
20
H
27
N
2
Fe BF
4
requires
323.7 (2.8%); Anal. Calc. for C18
H
23
N
2
Fe ; [M ]ꢀPF
6
, 323.12051.
+
M ]ꢀBF
4
, 351.15236).
4
.3.9. 1-(Ferrocenylmethyl)-3-octylimidazolium hexafluorophosphate
1
7
4.3.5. 1-(6-Ferrocenylhexyl)-3-butylimidazolium tetrafluoroborate 13
This salt was synthesised following a similar method to 9 using
an excess of sodium hexafluorophosphate (0.55 g, 3.27 mmol) and
-(ferrocenylmethyl)-3-octylimidazolium bromide (0.39 g,
0.84 mmol) to yield an orange-yellowish paste identified as 17
This salt was synthesised following a similar method to 9 using
sodium tetrafluoroborate (0.70 g, 6.34 mmol) and 1-(6-ferro-
cenylhexyl)-3-butylimidazolium bromide (3.00 g, 6.34 mmol) to
1
ꢀ1
give a brown oil identified as 13 (2.83 g, 93%); IR (CHCl
3
cm
)
ꢀ1
(
0.42 g, 95%); mp 74 °C; IR (ATR cm ) 2928, 1709, 1366, 1233,
3
1
(
153, 3095, 3031, 2937, 2861, 1697, 1564, 1467, 1362, 1288,
1
1
3
1150, 824, 556, 501, 483; H NMR (CDCl ) 8.61 (1H, s, NCH), 7.12
219, 1165, 1062, 858, 821, 670, 520, 483; H NMR (CDCl
3
), 8.96
), 4.10
), 1.87 (4H,
), 0.96 (3H, t,
), 136.24, 122.65, 122.57, 89.49,
(
1
1H, s, NCH), 7.09 (1H, s, NCH), 5.17 (2H, s, CH
.8, C ), 4.26 (2H, t, J 1.8, C ), 4.23 (5H, s, C
J 7.1, CH ), 0.85 (3H, m, CH
), 1.24 (12H, m, 6 ꢂ CH
(CDCl ) 134.9, 121.4, 77.97, 77.2, 69.97, 69.50, 69.3, 50.3, 31.6,
2
), 4.36 (2H, t, J
1H, s, NCH), 7.34 (2H, m, 2 ꢂ NCH), 4.20 (4H, m, 2 ꢂ CH
5H, s, C ), 4.05 (4H, m, C ), 2.31 (2H, t, J 7.3, CH
), 1.48 (2H, m, CH
), 1.35 (6H, m, 3 ꢂ CH
2
H
4
H
5 4
5 5
H ), 4.09 (2H, t,
(
H
5 5
H
5 4
2
5
13
3
); C NMR
m, 2 ꢂ CH
2
2
2
2
2
1
3
J 7.2, CH
3
);
C NMR (CDCl
3
3
2
9.9, 28.9, 26.2, 22.6, 14.0; m/z (ESI) 197.0 (2.9%), 198.6 (100%),
6
2
2
(
4
8.95, 68.52, 67.52, 50.47, 50.26 32.38, 31.33, 30.50, 29.85, 29.20,
+
199.3 (12.9%), 293 (1.2%), 377 (1.4%), 378.1 (1.1%), 378.9
6.47, 19.80, 13.79; m/z (FAB) 480 (M , 10%), 393 (100%), 347 (8),
+
ꢀ
+
(
M ꢀPF , 27%), 379.7 (7.2%); Anal. Calc. for
22 29 2
C H N Fe ;
72 (12), 200 (10), 179 (9), 165 (8), 151 (17), 138 (18), 121 (18);
6
+
+
+
[M ]ꢀPF , 377.16801.
Found: [M ], 480.202425.
80.202232).
C
23
H
33
N
2
FeBF
4
requires [M ],
6
4.3.10. 1-(6-Ferrocenylhexyl)-3-methylimidazolium
hexafluorophosphate 18
4.3.6. 1-(6-Ferrocenylhexyl)-3-octylimidazolium tetrafluoroborate 14
This salt was synthesised following a similar method to 9 using
sodium hexafluorophosphate (0.70 g, 4.18 mmol) and 1-(6-ferro-
cenylhexyl)-3-methylimidazolium iodide (2.00 g, 4.18 mmol) to
yield a yellow solid identified as 18 (1.99 g, 96%), mp 93 °C; IR
This salt was synthesised following a similar method to 9 using
sodium tetrafluoroborate (0.63 g, 5.68 mmol) and 1-(6-ferro-
cenylhexyl)-3-octylimidazolium bromide (3.00 g, 5.67 mmol) to
ꢀ1
give a brown oil identified as 14 (2.80 g, 92%); IR (CHCl
3
cm
)
ꢀ1
(
KBr cm ) 3083, 2944, 2925, 2858, 1575, 1635,1575, 1565,
3
8
026, 2933, 2860, 1695, 1586, 1563, 1468, 1207, 1163, 1065,
1
7
7
CH
2
468, 1460,1434, 1320, 1224, 1163, 1105, 1039, 1022, 1003, 854,
1
22, 670, 514, 485; H NMR (CDCl
3
), 9.17 (1H, s, NCH), 7.25 (2H,
and C ), 4.14 (5H, s, C ),
), 1.30 (14H, m, 7 ꢂ CH ), 0.91 (3H, t, J 7.2,
); C NMR (CDCl ), 136.24, 122.65, 122.57, 89.49, 68.95,
1
62, 725, 661, 625, 556, 487; H NMR (CDCl
.33 (1H, t, J 1.7, NCH), 7.29 (1H, t, J 1.7, NCH), 4.21 (2H, t, J 7.5,
), 4.11 (5, s, C ), 4.06 (4H, m, C ), 3.99 (3H, s, NCH ),
.32 (2H, t, J 7.5, CH ), 1.89 (2H, m, CH ), 1.46 (2H, m, CH ), 1.36
) 136.86, 123.87, 122.31, 89.55,
9.03, 68.60, 67.57, 50.61, 37.05, 31.29, 30.39, 29.84, 29.16,
3
) 9.18, (1H, s, NCH),
m, 2 ꢂ NCH), 4.97 (8H, m, 2 ꢂ CH
2
5
H
4
5 5
H
1
CH
6
1
(
(
.76 (8H, m, 4 ꢂ CH
2
2
H
5 5
H
5 4
3
1
3
2
3
3
2
2
2
8.52, 50.47, 32.38, 31.33, 30.50, 29.85, 29.20, 26.47, 19.80,
1
3
(
6
2
4H, m, 2 ꢂ CH
2 3
); C NMR (CDCl
+
3.79; m/z (FAB) 536 (M , 24%), 450 (100), 404 (8), 328 (8), 293
5), 271 (10), 250 (11), 236 (12), 221 (11), 207, (20), 186 (5), 151
+
+
6.47; m/z (FAB) 496 (M , 20%), 351 (M ꢀPF
6
, 100%), 329 (6), 306
+
4), 137 (9), 121 (25), 109 (13); (Found: [M ], 536.264943.
(
(
[
6), 284 (5), 268 (14), 230 (11), 212 (11), 199 (38), 186 (12), 176
45), 165 (4), 151 (18), 137 (28), 121 (35), 109 (35); (Found:
+
C
27
H
41
N
2
FeBF
4
requires [M ], 536.264832).
+
+
27 2 6
M ], 496.116636. C20H N FePF requires [M ], 496.116546).
4
.3.7. 1-(Ferrocenylmethyl)-3-methylimidazole hexafluorophosphate
1
5
4
.3.11. 1-(Ferrocenylmethyl)-3-methylimidazole
This salt was synthesised following a similar method to 9 using
hexafluoroantimonate 19
sodium hexafluorophosphate (0.13 g, 0.76 mmol) and 1-(ferroce-
nylmethyl)-3-methylimidazolium iodide (0.30 g, 0.74 mmol) to
yield 0.23 g, 72% of an orange crystals identified as 15; mp 66–
This salt was synthesised following a similar method to 9 using
sodium hexafluoroantimonate (0.1958 g, 0.7568 mmol) and 1-
(
ferrocenylmethyl)-3-methylimidazolium
iodide
(0.3092 g,
ꢀ
1
6
5
8 °C; IR (ATR cm ) 3429, 1624, 1567, 1331, 1150, 812, 619,
54, 500, 480; H NMR (CDCl
0
6
1
4
.7596 mmol) to yield an orange powder identified as 19 (0.26 g,
1
3
) 9.05 (1H, s, NCH), 7.11 (1H, s,
), 4.39 (2H, t, J 1.8,
), 4.24 (5H, s, C ), 3.94 (3H, s,
3
C NMR (CDCl ) 136.06, 122.79, 121.23, 78.02, 77.23,
6%); mp 66 °C; IR (ATR cm ) 3072, 1706, 1566, 1445, 1409,
ꢀ1
NCH), 7.0868 (1H, s, NCH), 5.22 (2H, s, CH
C
CH
2
325, 1238, 1149, 1104, 1027, 999.7, 816, 734, 653, 619, 499,
5
H
4
), 4.23 (7H, t, J 1.8, C
5
H
4
5
H
5
1
80; H NMR (CDCl
3
) 9.94 (1H, s, NCH), 7.27 (1H, s, NCH), 7.23
), 4.45 (2H, m, C ), 4.29 (7H, m,
) 135.56, 123.16,
1
3
3
);
(
1H, s, NCH), 5.34 (2H, s, CH
5 4
H
2
6
9.97, 69.59, 69.19, 50.18; m/z 197 (2.3%), 198.6 (100%), 199.3
13
C
H
5 5
, C ), 4.02 (3H, m, CH ); C NMR (CDCl
5
H
4
3 3
+
þ
+
(
[
13.1%), 280.6 (M ꢀPF , 4.5%); Anal. Calc. for C15
17 2
H N Fe ;
6
121.62, 77.82, 77.23, 70.04, 69.68, 69.31, 50.42; m/z (ESI) 197.1
+
+
ꢀ
M ]ꢀPF
6
, 281.07411.
(
2.6%), 198.6 (100%), 199.2 (15%), 280.6 (M ꢀSbF ), 4.4%); Anal.
6
+
+
Calc. for C15
H
17
N
2
Fe ; [M ]ꢀSbF
6
, 281.07411.
4.3.8. 1-(Ferrocenylmethyl)-3-butylimidazolium hexafluorophosphate
1
6
4.3.12. 1-(Ferrocenylmethyl)-3-butylimidazolium
This salt was synthesised following a similar method to 9 using
hexafluoroantimonate 20
sodium hexafluorophosphate (0.30 g, 1.81 mmol) and 1-(ferroce-
nylmethyl)-3-butylimidazolium bromide (0.43 g, 1.08 mmol) to
yield a brown powder identified as 16 (0.48 g, 96%); mp 70 °C; IR
This salt was synthesised following a similar method to 9 using
sodium hexafluoroantimonate (0.38 g, 1.47 mmol) and 1-(ferroce-
nylmethyl)-3-butylimidazolium bromide (0.43 g, 1.08 mmol) to
yield dark brown-greenish powder identified as 20 (0.46 g, 77%);
ꢀ1
(
5
7
(
ATR cm ) 3639, 3167, 2934, 1562, 1448, 1154, 820, 775, 555,
1
ꢀ1
01, 478; H NMR (CDCl
.13 (1H, s, NCH), 5.17 (2H, s, CH
), 4.22 (5H, s, C
), 1.32 (2H, m, CH ), 0.93 (3H, m, CH
34.8, 121.6, 121.5, 78.1, 77.2, 69.9, 69.5, 69.3, 50.0, 31.8, 19.4,
3.3; m/z 125 (1.7%), 181.2 (13.6%), 182.1 (1.6%), 197 (2.4%),
3
) 8.62 (1H, s, NCH), 7.15 (1H, s, NCH),
), 4.37 (2H, t, J 1.8, C ), 4.25
), 4.11 (2H, t, J 5.8, CH ), 1.81
); C NMR (CDCl
mp 52 °C; IR (ATR cm ) 3155, 2965, 1561, 1467, 1321, 1239,
1
2
5
H
4
1148, 1105, 828, 749, 650, 482; H NMR (CDCl
3
) 8.44 (1H, s,
), 4.42
), 1.81
); C NMR (CDCl
134, 121.7, 77.3, 77.0, 70.6, 70.1, 69.9, 50.1, 31.8, 30.9, 19.4, 13.3;
2H, t, J 1.8, C
2H, m, CH
H
5 4
5
H
5
2
NCH), 7.16 (1H, s, NCH), 7.12 (1H, s, NCH), 5.07 (2H, s, CH
(2H, s, C ), 4.29 (7H, m, C , C ), 4.09 (2H, m, CH
(2H, m, CH ), 1.35 (2H, m, CH ), 0.94 (3H, m, CH
2
13
(
2
2
3
3
)
5
H
4
5
H
4
5
H
5
2
1
3
1
1
2
2
3
3
)

1
132
V.O. Nyamori et al. / Journal of Organometallic Chemistry 695 (2010) 1126–1132
m/z (ESI) 125.0 (2.4%), 181.1 (14.2%), 181.9 (1.4%), 197.0 (2.9%),
98.5 (100%), 199.3 (14.9%), 200.5 (1.4%), 320.8 (2.6%), 322.7
Appendix A. Supplementary data
1
+
ꢀ
+
+
(
M ꢀSbF , 2.4%); Anal. Calc. for
C
18
23
H N
2
Fe ; [M ]ꢀSbF
6
,
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2010.01.019.
6
3
23.12051.
References
4.3.13. 1-(ferrocenylmethyl)-3-octylimidazolium
hexafluoroantimonate 21
[
1] (a) J. Ohmori, M. Shimizu-Sasamata, M. Okada, S. Sakamoto, J. Med. Chem. 39
(1996) 3971;
This salt was synthesised following a similar method to 9 using
an excess of sodium hexafluoroantimonate (0.5332 g, 2.061 mmol)
and 1-(ferrocenylmethyl)-3-octylimidazolium bromide (0.3850 g,
(
b) Y.S. Lo, J.C. Nolan, T.H. Maren Jr., W.J. Welstead, D.F. Gripshover, D.A.
Shamblee, J. Med. Chem. 35 (1992) 4790;
c) P. Cozzi, G. Carganico, D. Fusar, M. Menichincheri, V. Pinciroli, R. Tonani, F.
(
0
.8402 mmol) to yield a dark brown-greenish oil identified 21
Vaghi, P. Salvati, J. Med. Chem. 36 (1993) 2964;
(d) T. Güngngor, A. Fouquet, J.M. Teulon, D. Provost, M. Cazes, A. Cloarec, J.
Med. Chem. 35 (1992) 4455;
ꢀ1
(
1
(
0.4819 g, 93.4%); IR (ATR cm ) 3155, 2928, 1709, 1561, 1467,
320, 1148, 1106, 828, 746, 652, 501, 482; 1H NMR (CDCl3) 8.44
1H, s, NCH), 7.20 (1H, s, NCH), 7.14 (1H, s, NCH), 4.86 (2H, s,
(
e) G.R. Martinez, K.A.M. Walker, D.R. Hirschfeld, J.J. Bruno, D.S. Yang, P.J.
Maloney, J. Med. Chem. 35 (1992) 620;
f) H.M. Lee, S.P. Nolan, Org. Lett. 2 (2000) 2053;
(g) W.A. Herrmann, C. Köcher, Angew. Chem., Int. Ed. Engl. 36 (1997) 2161;
h) A.L. Johnson, J.C. Kauer, D.C. Sharma, R.I. Dorfman, J. Med. Chem. 12 (1969)
(
CH
CH
1
2
1
2
), 4.60 (2H, s, C
5
H
4
), 4.47 (7H, m, C
5 4 5 5
H , C H ), 4.09 (2H, s,
13
2
), 1.29 (12H, m, C
6
H12), 0.86 (3H, m, CH ); C NMR (CDCl )
3 3
(
34.64, 121.96, 121.91, 77.34, 77.23, 50.65, 50.20, 31.65, 30.06,
1024;
9.70, 28.98, 28.86, 26.27, 22.59, 14.07; m/z (ESI) 197.1 (2.7%),
(i) Y.-K. Li, H.-S. Hsu, L.-F. Chang, G. Chen, J. Biochem. 123 (1998) 416.
ꢀ
[2] (a) J.-L. Thomas, J. Howarth, A.M. Kennedy, Molecules 7 (2002) 861;
b) Y. Gao, B. Twamley, J.M. Shreeve, Inorg. Chem. 43 (2004) 3406.
98.6 (100%), 199.3 (14.3%), 378.8 (M+ꢀSbF , 10%), 379.8 (1.7%);
6
(
+
+
Anal. Calc. for C22
H
29
N
2
Fe ; [M ]ꢀSbF
6
, 377.16801.
[
[
[
[
3] H.-W. Yu, J.-C. Shi, H. Zhang, P.-Y. Yang, X.-P. Wang, Z.-L. Jin, J. Mol. Catal. A:
Chem. 250 (2006) 15.
4] R. Balasubramanian, W. Wang, R.W. Murray, J. Am. Chem. Soc. 128 (2006)
9
994.
5] W. Wang, R. Balasubramanian, R.W. Murray, J. Phys. Chem. C 112 (2008)
8207.
4.3.14. 1-(6-Ferrocenylhexyl)-3-methylimidazolium
1
hexafluoroantimonate 22
6] B. Bildstein, M. Malaun, H. Kopacka, K. Wu rst, M. Mitterböck, K.-H. Ongania, G.
Opromolla, P. Zanell, Organometallics 18 (1999) 4325.
[7] A.J. Arduengo III, R.L. Harow, M. Kline, J. Am. Chem. Soc. 113 (1991) 361.
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Starikova, A.I. Yanovsky, A.F. Kolomiets, V.N. Babin, J. Organomet. Chem. 580
This salt was synthesised following a similar method to 9 using
sodium hexafluoroantimonate (1.08 g, 4.18 mmol) and 1-(6-ferro-
cenylhexyl)-3-methylimidazolium iodide (2.00 g, 4.18 mmol) to
give a yellow solid identified as 22 (2.33 g, 95%), mp 68 °C; IR
[
(
1999) 26;
ꢀ1
(
KBr cm ) 3164, 3119, 2924, 2857, 1628, 1572, 1467, 1431,
(b) L.V. Snegur, A.A. Simenel, Y.S. Nekrasov, E.A. Morozova, Z.A. Starikova, S.M.
Peregudova, Y.V. Kuzmenko, V.N. Babin, L.A. Ostrovskaya, N.V. Bluchterova,
M.M. Fomina, J. Organomet. Chem. 689 (2004) 2473.
1
7
374, 1337, 1319, 1224, 1165, 1105, 1022, 1002, 922, 840, 821,
59, 726, 661, 625, 514, 484, 423; 1H NMR (CDCl
) 9.58, (1H, s,
3
[
9] J. Howarth, K. Hanlon, Tetrahedron Lett. 42 (2001) 751.
NCH), 7.41 (1H, t, J 1.7 NCH), 7.33 (1H, t, J 1.7, NCH), 4.26 (2H, t,
CH ), 4.10 (5H, s, C ), 4.04 (7H, m, CH and C ), 3.99 (3H, s,
NCH ), 2.32 (2H, t, J 7.5, CH ), 1.90 (2H, m, CH ), 1.49 (2H, m,
CH ), 136.88, 124.00,
[10] B. Bildstein, J. Organomet. Chem. 617–618 (2001) 28.
[
11] P.T. Anastas, C. Warner, Green Chemistry: Theory and Practice, Oxford
University Press, Oxford, 1998.
2
5
H
5
3
5 4
H
3
2
2
[
12] B.C. Ranu, U. Jana, A. Majee, Green Chem. 1 (1999) 33.
13
2
), 1.36 (4H, m, 2 ꢂ CH
2
); C NMR (CDCl
3
[13] V. César, S. Bellemin-Laponnaz, L.H. Gade, Chem. Soc. Rev. 33 (2004) 619.
[
[
[
14] D. Onyancha, V.O. Nyamori, C.W. McCleland, C. Imrie, T.I.A. Gerber, J.
Organomet. Chem. 694 (2009) 207.
15] A.A. Simenel, E.A. Morozova, Y.V. Kuzmenko, L.V. Snegur, J. Organomet. Chem.
665 (2003) 13.
16] (a) K. Plesske, Angew. Chem., Int. Ed. 1 (1962) 312;
(b) D.E. Bublitz, K.L. Rinehart Jr., Organic Reactions, vol. 17, John Wiley and
Sons, New York, 1969, p. 23. and references therein;
1
2
2
22.45, 89.46, 68.95, 68.54, 67.51, 50.63, 37.32, 31.31, 30.52,
9.85, 29.21, 26.50; m/z (FAB) 587 (M , 11%) 351 (100), 268 (10),
+
30 (11), 212 (10), 199 (30), 186 (10), 151 (20), 137 (24), 121
+
(
[
28), 109 (30); (Found: [M ], 587.054774. C20
H
27
N
2
FeSbF
6
requires
+
M ], 587.054432).
(
c) R. Vukicevic, Z.R. Ratkovic, M.D. Vukicevic, S.K. Konstantinovic,
Tetrahedron Lett. 39 (1998) 5837. and references therein.
17] P. Wasserscheid, T. Welton, Ionic Liquids in Synthesis, vol. 1, Wiley-VCH,
Weinheim, 2008. p. 62.
[
[
[
Acknowledgements
18] J.-L. Thomas, J. Howarth, K. Hanlon, D. McGuirk, Tetrahedron lett. 41 (2000)
413.
The authors wish to thank the University of KwaZulu-Natal for
financial support and the School of Chemistry for availing its
facilities.
19] C.K. Lau, S. Tardif, C. Dufresne, J. Scheigetz, J. Org. Chem. 54 (1989) 491.