The synthesis and liquid crystal behavior of monosubstituted ferrocenomesogens

Article abstract of DOI:10.1016/S0022-328X(02)02044-2

The synthesis and characterization of several new series of monosubstituted ferrocenyl-containing liquid crystals has been achieved. The results indicate that a terminal ferrocenyl group can promote stabilization of a nematic liquid crystal state. At leas

Full text of DOI:10.1016/S0022-328X(02)02044-2

Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
www.elsevier.com/locate/jorganchem
The synthesis and liquid crystal behaviour of monosubstituted
ferrocenomesogens
Christopher Imrie a,*, Christa Loubser a, Pieter Engelbrecht a, Cedric W. McCleland a,
Yifan Zheng b
a Department of Chemistry, University of Port Elizabeth, P.O. Box 1600, Port Elizabeth 6000, South Africa
b Inorganic Chemistry Laboratory, University of Oxford, South Parks Road OX1 3QR, UK
Received 1 July 2002
Abstract
The synthesis and characterization of several new series of monosubstituted ferrocenyl-containing liquid crystals has been
achieved. The results indicate that a terminal ferrocenyl group can promote stabilization of a nematic liquid crystal state. At least
three phenyl rings are required in the molecular core in order to provide nematic properties and addition of a fourth ring
substantially enhances it. Bulky lateral substituents or the introduction of linker groups that introduce kinks inhibit liquid crystal
phase formation. Short highly polarising terminal groups or terminal groups that support hydrogen bonding support liquid crystal
behaviour.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Ferrocenomesogens; Nematic phases; Liquid crystals
1. Introduction
Loubser et al. described the X-ray structure of a
monosubstituted ferrocenomesogen (4) [a ferrocenyl-
containing liquid crystal]. The molecule 4 contained a
terminal ferrocenyl group and laterally substituted
Maltheˆte and Billard synthesized the initial series of
mesogenic ferrocene derivatives [1]. Compounds of three
structural variation were synthesized (Fig. 1, 1ꢀ3) and in
/
each case the ferrocenyl group was situated in a terminal
position. The compounds of series 1 displayed enantio-
tropic nematic liquid crystal phases characterized by
their Schlieren texture but exhibited relatively short
liquid crystalline domains. The compounds of series 2
and 3 were monotropic nematogens.
The results of Maltheˆte and Billard were surprising at
the time in that it seemed likely that monosubstituted
ferrocenes would be poor candidates for stabilizing
liquid crystalline phases owing to disruption of the
overall linear shape of the molecule by the bulky
ferrocenyl group. It was only in 1993 that a publication
by Loubser et al. shed some light on the manner in
which a terminal ferrocenyl group can be incorporated
and tolerated in a liquid crystal [2]. The article by
* Corresponding author. Fax: ꢁ
/
27-41-5042573.
E-mail address: chacci@upe.ac.za (C. Imrie).
Fig. 1. The first monsubstituted ferrocenomesogens.
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 0 4 4 - 2

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
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49
fluorine atoms and exhibited an enantiotropic nematic
phase with a relatively low melting and clearing
temperature. Analysis of the molecular structure of 4
by X-ray diffraction indicated that there was an inter-
molecular association between two molecules in neigh-
bouring layers resulting in an overall extended S-shape
with the ferrocenylꢀphenyl groups forming the ‘core’
/
and the remainder of each pair of molecules extending in
opposite but parallel directions.
the thermal and photochemical stabilities. Insertion of
the spacer group attenuates the withdrawal of electron
density from the ferrocenyl group, which would have
resulted in a reduction of Cpꢀ
/
Fe back donation and
ligand bonds.
subsequent weakening of the metalꢀ
/
Compounds lacking the spacer were also found to be
more prone to hydrolysis during the purification proce-
dure.
Several other researchers have reported interesting
results in the area of monosubstituted ferrocenomeso-
gens and the field has been the subject of a recent review
article [4]. In this current article, we present our latest
This stimulated a systematic investigation into the
structural limits in which the liquid crystalline state can
be generated and retained in monosubstituted ferroce-
nomesogens, which was undertaken by Loubser and
Imrie over the period 1993ꢀ1997 [3]. The authors
/
results on the structureꢀliquid crystals activity of
/
synthesized a series of molecules based on the general
structure 5. The authors determined that a minimum of
three benzene rings and a ferrocenyl group in the
molecular core could stabilize the nematic phase, but
that addition of a fourth benzene ring greatly enhanced
nematic behaviour. The nematic phase was destabilized
by increasing the length of the terminal alkoxyl chain n,
and lateral fluorination reduced the nematic phase range
and suppressed smectic phases. It was shown that both
the number and position of the fluorine atoms on the
core was important. An alteration in the shape of the
core by moving the carbonyloxy linker group from the
4- to the 3-position resulted in a suppression of the
nematic phase as a result of introducing a kink into the
molecular structure.
monosubstituted ferrocenomesogens.
2. Results and discussion
2.1. Synthesis and properties of elongated ferrocenes
The ferrocenomesogens synthesized in this work were
designed according to the initial guidelines of Loubser
and Imrie. Hence, a benzene ring was inserted as a
spacer between the ferrocenyl group and the linker, and
the core of the molecule contained at least three benzene
rings (molecules contained a ferrocenyl group and at
least three benzene rings). Within this framework, other
variables with regard to the general structure 5 were of
interest to us. These included, the effect of switching the
Loubser and Imrie also highlighted the importance of
taking into account stability considerations when de-
signing new organometallic liquid crystals. It was shown
that the insertion of a benzene ring as a spacer between
the ferrocenyl group and carbonyloxy linker resulted in
a lowering of clearing temperature and increased both
linker group from ꢀ
making jꢂ2, the effect of introducing different
linker groups such as Nꢀ CH2OOCꢀ
CHꢁ
CH(CH3)OOCꢀ, the effect of lengthening the core
/
COOꢀ
/
to ꢀ
/
OOCꢀ
/
, the effect of
/
ꢀ
/
/
/
,
ꢀ
/
/,
ꢀ
/
/

50
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
and the effect of using shorter terminal groups (CN and
OCOOCH3).
nematic phase. As the length of the terminal alkoxyl
chain increased, smectic behaviour developed and the
The total synthesis of series 6 (nꢂ3, 5, 8, 9, 10, 12, 14)
/
compounds where nꢂ
tic A phases (the compound where nꢂ
short monotropic smectic C phase), and those with
longer chains (nꢂ12, 14) enantiotropic smectic A and
/
8ꢀ
/
10 exhibited monotropic smec-
is illustrated in Scheme 1 and is representative of the
types of reaction used in the synthesis of all series. 4-
Ferrocenylphenol (7), synthesized via the Suzuki cross-
coupling reaction of iodoferrocene and 4-benzyloxyben-
zeneboronic acid or by the diazonium method [5] was
reacted with a series of 4?-alkoxy-4-biphenylcarboxylic
/9 also exhibited a
/
monotropic smectic C phases. The texture of the smectic
A phase was often observed as homeotropic, but some-
times it was seen as a focal conic as in Fig. 3. The
smectic C phase was usually observed as a Schlieren
texture developing from the homeotropic smectic A
phase. The compounds of series 6 showed a reduction in
clearing temperature as the length of the terminal
alkoxyl chain increased (Fig. 4); this type of behaviour
has been observed previously [3]. The enthalpies of
transition for the compounds of series 6 appear in Table
2.
acids (8) (nꢂ3, 5, 8, 9, 10, 12, 14). The acids (8) were
/
synthesized in three steps from 4-hydroxy-4?-biphenyl-
carboxylic acid. The etherification steps were performed
using an adaption of the Finkelstein reaction [6] and
good-to-excellent yields were achieved (46ꢀ98%). The
/
final step in the syntheses of the compounds of series 6
involved the esterification of 8 which was accomplished
by treating 8 with 7 in the presence of dicyclohexylcar-
bodiimide (DCC) and 4-dimethylaminopyridine
(DMAP).
Two series of precursors of 6 (8 and 9) were also
mesogenic (with the exception of 9 where nꢂ3, 5) and
/
The phase transition temperatures of the compounds
of series 6 (and all subsequent series) were determined
from optical microscopy and differential scanning
calorimetry (DSC). The phase transition temperatures
for the series are provided in Table 1. All the
compounds in series 6 exhibited stable nematic phases
with characteristic Schlieren textures (Fig. 2) with the
the observed phase transition temperatures correlated
closely with those reported earlier by Gray et al. [7].
Comparing the phase behaviour of compounds in series
6 with their precursors (series 8) illustrates the ability of
a terminal ferrocenylꢀ
nematic liquid crystalline state. For example, in series
8, the molecules where nꢂ12 and 14 do not exhibit
/phenyl group to stabilize the
/
exception of the compounds where nꢂ
/
3 which was non-
nematic behaviour and those in the series with shorter
terminal chains have very narrow nematic ranges [7].
mesogenic and nꢂ5 which exhibited a monotropic
/
Scheme 1. The synthesis of 4-ferrocenylphenyl 4?-alkoxy-4-biphenylcarboxylates.

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
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51
A comparison of the phase behaviour of compounds
in series 6 with those of series 5 (jꢂ1, iꢂ2, XꢂH, Yꢂ
/
/
/
/
COO) synthesized by Loubser and Imrie previously, in
which there has been a reversal of the carbonyloxy
linkage, shows that aside from the different smectic
behaviour, compounds in the two series have remark-
ably similar nematic behaviour and similar clearing
temperatures. This is in contrast to results published
by Deschenaux et al. in relation to isomeric 1,3- and
1,1?-disubstituted ferrocene derivatives where the reor-
ientation of the ester functionality provided significantly
different liquid crystal properties [8].
Loubser and Imrie previously established that a
minimum of three benzene rings in the molecular core
(total number of rings in moleculeꢂ
/
1Fcꢁ3Ph) stabi-
/
lized the nematic phase and that the addition of a fourth
benzene ring greatly enhanced nematic behaviour.
However, since the latter conclusion was based on the
properties of only two molecules, series 10 was synthe-
sized in which another benzene ring was introduced into
the core in relation to the compounds of series 6,
lengthening the linear rod-like shape of the general
structure.
The total synthesis of the compounds of series 10 (nꢂ
/
5, 8, 9, 10, 12, 14) is illustrated in Scheme 2. The
compounds of this series exhibited very broad and high
temperature nematic phases (Table 3) and decomposi-
tion was evident for these compounds above 250 8C.
Two of the compounds of series 10 (nꢂ5, 8) exhibited
/
crystal-to-crystal transitions. The transitions generally
occurred from a fluffy texture to a more structured
texture.
A comparison of the phase behaviour of one of the
compounds in series 10 (nꢂ8) and a compound made
/
previously by Loubser and Imrie (11) highlights the
effect of lateral fluorination. Both compounds exhibited
enantiotropic nematic phases with very broad liquid
crystalline domains, 84 8C for 10 (nꢂ8) and 100 8C for
/
11. However, in the latter compound, there is a
significant lowering of the clearing and melting points.
This trend parallels that observed for organic liquid
crystals when the introduction of a highly electronega-
tive fluorine atom is known to be effective at reducing
the melting point without disrupting the overall phase
behaviour.
The insertion of additional methylene (CH2) and
methylmethine CH(CH3) spacers between the benzene
ring of the ferrocenylphenyl unit and the carbonyloxy
linkage resulted in the non-mesogenic derivatives 12 and
13 (Table 4). The new linker groups ꢀ
CH(CH3)OOCꢀ would prevent conjugation between the
ferrocenylꢀphenyl group and the rest of the molecule
/
CH2OOCꢀ
/
and ꢀ
/
/
/
which in turn would affect the polarity of the molecule.
Computer modelling of compounds in series 6, 12 and
13 (see Section 2.3) indicated that the introduction of the
ꢀ
/
CH2ꢀ
/
and ꢀ
/
CH(CH3)ꢀ
/
spacers resulted in significant

52
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
Table 1
The phase transition temperatures of series 6
a
Phase transition temperatures were calculated from a combination of optical microscopy and DSC.
Abbreviations: K, crystalline; SA, smectic A-phase; Sc, smectic C-phase; N, nematic phase; I, isotropic liquid.
b
observations reported by Loubser and Imrie; nematic
phase behaviour was suppressed when the shape of the
core was altered by moving the carbonyloxyl linkage
from the 4- to the 3-position with respect to the
kinks in the molecular backbone of molecules in series
12 and 13. The resultant kinks decrease the length/depth
(l/d) ratio of the molecules and when this drops below a
certain value, the molecules become non-mesogenic. The
results of the kinking effect are consistent with previous
Fig. 2. Photomicrograph of a ferrocenomesogen in series 6 with a
nematic phase exhibiting a Schlieren texture.

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
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53
involvement of hydrogen bonding in the development of
an extended molecular architecture (see Section 2.2).
Not surprisingly, 4-methoxycarbonyloxy-4?-phenylfer-
rocene (16) (1Fcꢁ1Ph ring) proved to be non-mesogenic
/
and it does not conform to the guidelines established by
Loubser and Imrie even, upon dimerization.
In the next facet of our work, we focused on
modification of the n-alkoxy terminal group and
compounds 17ꢀ20 were synthesized. In compounds 17
/
and 18, the terminal group was modified to a benzoate
unit by insertion of an additional carbonyl group.
Compound 17 exhibited a monotropic nematic phase
whereas 18 proved to be non-mesogenic. The reduction
of liquid crystalline properties in compounds 17 and 18
Fig. 3. Photomicrograph of a ferrocenomesogen in series 6 with a
smectic A phase exhibiting a focal conic texture.
in relation to those of 5 (jꢂ
/
1, iꢂ
/
2, Yꢂ
/
COO, XꢂH,
/
nꢂ8) or 6 (nꢂ8) upon introduction of a carbonyl
/
/
ferrocenyl group. The compounds of series 12 also
group could possibly be rationalized in terms of a
reversal of mesomerism resulting in an alteration of
polarizability and intermolecular interactions. The in-
troduction of an extra carbonyl group in 17 and 18
results in an additional kink in the molecular structure
of these compounds with respect to 5 and 6 which would
lead to a lower l/d ratio. Due to the non-mesogenic
behaviour of 18 it was decided not to synthesize its
chiral analogue (starting from S-(2)-octanol) as it is
highly unlikely that this ferrocene derivative would be
mesogenic.
In compounds 19 and 20, the terminal n-alkoxy
chains used in previous series were replaced with
terminal cyano groups. The cyano group is frequently
used as the terminal group in liquid crystals as it is
highly polarizable. Compounds synthesized by Gray et
al. [7] which were at the forefront of the commercial
exploitation of liquid crystals for electrooptic displays
incorporated terminal cyano groups. The cyano group is
known to stabilize the nematic phase and so we were
most interested in investigating the effect of having a
exhibited changes in the crystalline form (crystalꢀcrystal
/
modifications) on heating and these modifications
proved to be reproducible but were not observed by
DSC. The methods used in the synthesis of 12 and 13
were similar to those described previously except that
the esterification of compounds in series 13 was achieved
by the Mitsunobo reaction instead of the DCC/DMAP
protocol.
In an extension of series 6, compounds 14 and 15 were
synthesized. Compound 14 exhibited an enantiotropic
nematic phase with characteristic Schlieren textures,
whilst compound 15 proved to be non-mesogenic. A
DSC spectrum for 14 is shown in Fig. 5 and is
representative of those obtained for most of the
ferrocenomesogens. The solid state to nematic phase
and nematic phase to isotropic liquid transitions are
clearly observed. The phase behaviour of 14 may seem
anomalous when compared to the compounds of series 6
especially those where nꢂ
/
3 and 5 (Table 1). However,
X-ray crystallography of 14 provided evidence for the
Fig. 4. Phase distribution for the molecules in series 6.

54
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
Table 2
The enthalpies of transition (DH/kJ molꢃ1) as observed for the compounds of series 6
n
K0
/
I
K0/SA
K0
/
N
SA0/N
N0/I
I0
/
N
N0/K
N0
/
SA
SA0
/
K
SA0/SC
SC0K
/
5
8
9
33.3
ꢀ
ꢀ/
ꢀ/
ꢀ/
28.6
27.2
/
ꢀ
/
ꢀ
ꢀ/
ꢀ/
ꢀ/
0.75
0.69
/
ꢀ
/
7.52
1.33
1.06
0.50
1.02
0.98
21.52
ꢀ
/
ꢀ
/
ꢀ
ꢀ/
/
ꢀ
ꢀ/
/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
41.9
33.9
48.8
1.02
1.12
0.21
0.85
0.80
ꢀ/
ꢀ/
ꢀ/
ꢀ/
25.7*
NS
NS
25.7*
ꢀ/
36.1
NS
NS
10
12
14
ꢀ/
NS
NS
ꢀ/
26.3
22.2
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
Abbreviations: K, crystalline; SA, smectic A-phase; Sc, smectic C-phase; N, nematic phase; I, isotropic liquid; NS, observed by polarized optical
microscopy only; *, only one large unresolved peak was observed for the two transitions.
terminal cyano and ferrocenyl group (a group which
also appears to stabilize nematic phases) in the same
molecule. Compound 19 exhibited a relatively short-
and high-temperature nematic phase. A comparison of
siderably elevates the clearing temperature (an increase
of between 70 and 109 8C).
Compound 20 in which an additional benzene ring
(1Fcꢁ4Ph) was introduced with respect to 19 exhibited
/
a relatively broad very high temperature nematic phase.
Comparing the behaviour of compound 20 with its n-
alkoxy analogues 10 once more showed the complete
suppression of smectic behaviour upon introduction of
compound 19 with its n-alkoxyl analogues 5 (jꢂ
/
1, iꢂ2,
/
YꢂCOO, XꢂH, nꢂ8, 10, 12, 14) revealed that the
/
/
/
introduction of a terminal cyano group resulted in the
complete suppression of smectic behaviour and con-
Scheme 2. The total synthesis of series 10.

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
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55
Table 3
The phase transition temperatures of series 10
a
Phase transition temperatures were calculated from a combination of optical microscopy and DSC.
Abbreviations: K, crystalline; SA, smectic A-phase; Sc, smectic C-phase; N, nematic phase; I, isotropic liquid.
the terminal cyano group. It was, however, not feasible
to compare the liquid crystal domain size of these
compounds (20 and 10) since 20 showed evidence of
decomposition above 250 8C.
exhibits a short but stable nematic liquid crystal phase.
The molecular structure of 14 together with numbering
scheme is shown in Fig. 6. The unit cell is triclinic and
the bond lengths and angles fall within the expected
limits (Table 5). The molecular geometry is extended
and linear. The two cyclopentadienyl rings in the
ferrocenyl group are eclipsed. The cyclopentadienyl
ring and the adjacent phenyl ring are tilted at an angle
of 1.38 with respect to one another. The phenyl rings in
the biphenyl group are tilted at an angle of 2.28 with
respect to one another. The biphenyl unit is approxi-
mately orthoganol to the ferrocenylphenyl unit. The
molecular packing is depicted in Fig. 7. This emphasizes
the interesting arrangement between molecules within a
layer and between two layers. The molecules are ar-
ranged parallel to each other in an extended fashion in a
head-to-tail/tail-to-head format. The position of the
formate ester groups allows for hydrogen bonding
between O(2) in one molecule and HÁ Á ÁC(58) in another
molecule. The distance between O(2) and C(58) is 3.129
The series of Schiff’s bases 21 (nꢂ5, 8, 14) were
/
synthesized, as we were interested in observing the effect
of introducing a terminal ferrocenylbiphenyl unit into
ferrocenomesogens. The compounds of series 21 were
synthesized by the reaction of 4-formyl-4?-biphenylfer-
rocene with a series of n-alkoxyanilines [9]. The
compounds where nꢂ
smectic and nematic phases, whereas the compound
where nꢂ5 exhibited a monotropic nematic phase. In
/
8 and 14 exhibited enantiotropic
/
general, liquid crystal domains were short and once
again, the effects of increasing the length of the alkoxyl
chain with relation to the lowering of clearing tempera-
tures were observed.
Finally, the compounds of series 22 were synthesized
in which a lateral chlorine atom was introduced on the
benzene ring of the ferrocenylphenyl unit. The com-
pounds of series 22 exhibited low-temperature mono-
tropic nematic phases with characteristic Schlieren
textures.
˚
˚
A and between O(2)ꢀ
/
HC(58) 2.4854 A. The O(2)ꢀ
/
HC(58) distance is well within the range to allow
hydrogen bonding. pꢀp Stacking of the aromatic rings
/
enforces the extended molecular arrangement. For
example, the average intermolecular distance between
2.2. Crystal structure of 4-methoxycarbonyloxy-4?-
biphenylcarboxyphenylferrocene
the aromatic ring containing C41ꢀ
/
C46 to the ring
C55 is 3.69 A. Recently, Tse et al. [10]
reported p stacking between the aromatic planes of
˚
containing C51ꢀ
/
Compound 14 containing a bulky terminal ferrocenyl
group and a short terminal methoxycarbonyloxy group

56
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
Table 4
The phase transition temperatures and melting points of series 12 and 13
a
Phase transitions are quoted as observed with optical microscopy.
vb Abbreviations: K, crystalline; I, isotropic liquid.
some cyclometallated platinum(II) polymeric structures
˚
with an average distance of 3.68 A.
3. Conclusion
Monosubstituted ferrocene derivatives with large
enough l/d ratios can support liquid crystal behaviour.
The terminal ferrocenyl group is particularly good at
supporting stable nematic phases and phase behaviour is
normally observed at temperatures in excess of 100 8C.
Large lateral or linker groups that introduce kinks in
these molecules inhibit liquid crystal formation.
2.3. Structureꢀ
ferrocenes
/
liquid crystal properties of elongated
In order for a molecule to exhibit calamitic meso-
morphism, it should normally have a long linear shape
and a large enough l/d ratio so that significant inter-
molecular interactions can be generated. We have in one
of our previous papers [9] reported on conformational
searches on molecules in series 6, 12, 13, and 21.
Calculation of the approximate l/d ratios was carried
out for molecules in each series (for molecules with an
octyloxy terminal group). The clear trend from these
results was that monosubstituted ferrocenomesogens
have a much larger l/d ratio than non-liquid crystalline
elongated ferrocenes. The lowest energy conformation
of non-mesogenic molecules in series 12 and 13 show
pronounced kinks in the molecular structure that result
in lower l/d values.
4. Experimental
4.1. Purification and characterization of the materials
All reactions were performed under an atmosphere of
dry nitrogen. Silica gel 50 or Al2O3 (active, neutral,
Brockmann Grade I) were used for column chromato-
graphy. Plate chromatography was performed on a
model 7924T Harrison chromatotron using silica gel
60PF-254 as adsorbent with CaSO4 as binder or thin
layer preparative chromatography plates using Merck
silica gel 60 F254 (1.5 mm). Melting points were recorded

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
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57
Fig. 5. DSC spectrum of compound 14.
on an Electrothermal IA 900 series digital melting point
apparatus and are uncorrected. IR spectra were re-
at Oxford University. Transition temperatures were
investigated by DSC utilizing a Du Pont 910 DSC cell,
connected to a Du Pont 9000 Thermal Analyser.
Compounds were studied at various scanning rates
(2.5, 5 or 10 8C minꢃ1) for both the heating and cooling
cycle, after being encapsulated in aluminium pans. An
empty aluminium pan served as the reference. The
calorimeter was calibrated with an indium standard.
The textures of the mesophases were studied with a
standard Zeiss polarizing microscope equipped with a
Reichert hot stage at UPE and with a Nikon Eclipse
E600 optical polarizing microscope equipped with a
Linkam heating/freezing stage linked to a Linkam range
TMS 93 precision temperature control at Rhodes
University, Grahamstown. Photomicrographs were ta-
corded on a PerkinꢀElmer 1600 series Fourier Trans-
/
form IR spectrometer as KBr discs or as solutions in
1
CHCl3. H- and 13C-NMR spectra were recorded on a
Bruker Avance 300 MHz spectrometer as solutions in
CDCl3 or Me2SO-d6 using tetramethylsilane (Me4Si) as
internal standard; 1H-NMR peak frequencies are
quoted in ppm and coupling constants in Hz. Mass
spectra were recorded on an AEI MS 902/MSS update
(70 eV, direct insertion probe) at the Cape Technikon.
Microanalyses were performed by the Council for
Scientific and Industrial Research, Pretoria and at the
University of Cape Town. Crystal X-ray crystallography
was performed at the Inorganic Chemistry Laboratory
Fig. 6. Molecular structure of 14 with numbering scheme.

58
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
Table 5
tion, two different annotations are used. For example,
CH2Cl2/EtOH denotes that a mixture of two solvents
˚
Selected bond lengths (A) and angles (8) for compound 14
were used, whereas CH2Cl2ꢀEtOH denotes that CH2Cl2
/
Bond lengths
was used to dissolve the solid and the slow addition of
EtOH resulted in crystallization. The X-ray data were
Feꢀ
Feꢀ
Feꢀ
Feꢀ
Feꢀ
O(1)ꢀ
O(2)ꢀ
O(3)ꢀ
O(5)ꢀ
C(11)ꢀ
C(11)ꢀ
C(13)ꢀ
C(21)ꢀ
C(22)ꢀ
C(24)ꢀ
/
C(11)
C(12)
C(14)
C(13)
C(21)
2.034(5)
2.039(4)
2.042(4)
2.043(4)
2.050(5)
1.360(5)
1.201(6)
1.417(5)
1.322(6)
1.422(6)
1.485(6)
1.411(7)
1.416(8)
1.427(8)
1.424(8)
Feꢀ
Feꢀ
Feꢀ
Feꢀ
Feꢀ
O(1)ꢀ
O(3)ꢀ
O(4)ꢀ
O(5)ꢀ
C(11)ꢀ
C(12)ꢀ
C(14)ꢀ
C(21)ꢀ
C(23)ꢀ
/
C(15)
C(23)
C(22)
C(24)
C(25)
2.037(5)
2.040(4)
2.043(5)
2.046(4)
2.058(5)
1.423(5)
1.351(6)
1.179(7)
1.443(6)
1.439(6)
1.427(6)
1.429(7)
1.423(7)
1.413(7)
/
/
/
/
collected on an Enrafꢀ
/
Nonius DIP2000 image-plate
Ka radiation
0.71073 A). The images were processed with the
/
/
diffractometer with monochromated Moꢀ
/
/
/
˚
(lꢂ
/
/
C(37)
C(37)
C(54)
C(57)
/
C(34)
C(57)
C(57)
C(58)
DENZO and SCALEPAK programs [11]. The structure was
solved via direct methods [12] and refined by full-matrix
least-squares [13]. A representative synthesis of one
member of each of the series 6, 10, 12 and 13 is
provided. The full data on other members of each series
is provided in the supplementary information.
/
/
/
/
/
/
/
C(12)
C(31)
C(14)
C(22)
C(23)
C(25)
/
C(15)
C(13)
C(15)
C(25)
C(24)
/
/
/
/
/
/
/
/
/
4.2. Synthesis
Bond angles
C(11)ꢀ
C(15)ꢀ
C(57)ꢀ
/
Feꢀ
/
C(15)
41.41(17)
C(11)ꢀ
/
Feꢀ
O(1)ꢀ
/
C(12)
40.85(18)
115.0(4)
/
Feꢀ
/C(12)
68.95(19) C(37)ꢀ
115.4(4)
/
/
C(34)
4.2.1. 2-Chloro-4-ferrocenylbenzoic acid
/
O(3)ꢀC(54)
/
2-Chloro-4-ferrocenylbenzoic acid was synthesized by
the diazonium method. Quantities: 4-amino-2-chloro-
benzoic acid (5.35 g, 31.2 mmol), ferrocene (5.80 g, 31.2
mmol) and NaNO2 (2.90 g, 42.0 mmol). 2-Chloro-4-
ferrocenylbenzoic acid (0.57 g, 5%) was filtered off as
red crystals which were recrystallized from hot C3H6O,
ken with a Zeiss MC63 photo-micrographic camera
mounted on a standard Zeiss polarizing microscope
equipped with a Reichert hot stage. Reaction mixtures
were shaken on a Griffin flask shaker (896331/2). The
majority of the arylboronic acids were purchased from
Lancaster Synthesis (UK) and were used without further
purification. Unless otherwise stated all recrystalliza-
tions were performed at room temperature (r.t.). If more
than one solvent was used to perform the recrystalliza-
m.p. 180 8C (dec.); nmax(KBr)/cmꢃ1 3050ꢀ
2800 (br),
/
1686, 1598, 1565, 1505, 1427, 1407, 1306, 1257, 1162,
1104, 1089, 1044, 931, 906, 879; dH(Me2SO-d6) 7.67 (1H,
d, J 8.2, ArH), 7.58 (1H, s, ArH), 7.51 (1H, d, J 8.1,
ArH), 4.88 (2H, t, J 1.8, C5H4), 4.38 (2H, t, J 1.8,
C5H4), 3.99 (5H, s, C5H5); m/z 340 ([Mꢁ], 11%), 260
Fig. 7. Molecular packing diagram for compound 14.

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
/64
59
(5), 219 (18), 217 (5), 203 (5), 189 (5), 167 (5), 163 (5),
154 (7), 149 (21), 147 (7), 145 (5), 137 (5), 136 (7), 133
(6), 131 (6), 129 (9), 128 (5), 123 (6), 121 (7), 97 (16), 95
(21), 91 (20), 87 (15), 85 (17), 84 (40), 83 (27), 81 (27), 79
(15), 77 (15), 71 (34), 69 (48), 67 (28), 57 (100), 55 (77).
Anal. Found: C, 60.0; H, 4.4%; [Mꢁ], 339.9940. Calc.
for C17H13ClFeO2: C, 60.0; H, 3.8%; [Mꢁ], 339.9952.
71.0, 68.6, 57.5; m/z 533 (31%), 532 ([Mꢁ], 100), 530 (7),
337 (6), 336 (29), 278 (8), 277 (15), 256 (9), 255 (51), 168
(9), 140 (5), 139 (5). Anal. Found: C, 69.9; H, 4.5%;
[Mꢁ], 532.09716. Calc. for C31H24FeO5: C, 69.9; H,
4.5%; [Mꢁ], 532.0973.
4.2.4. 4-Ferrocenylphenyl 4?-hydroxy-4-
biphenylcarboxylate (15)
4.2.2. 4-Methoxycarbonyloxyphenylferrocene
4-Ferrocenylphenyl 4?-methoxycarbonyloxy-4-biphe-
nylcarboxylate (920 mg, 1.7 mmol) was suspended in a
mixture of CH2Cl2 (370 cm3), EtOH (75 cm3) and NH3
(35%, 55 cm3) and the mixture stirred overnight at r.t.
The solvents were removed in vacuo and the residue
purified by utilizing the insoluble nature of the com-
pound, impurities were washed out with CH2Cl2. The
residue was filtered leaving a yellow solid identified as 4-
ferrocenylphenyl 4?-hydroxy-4-biphenylcarboxylate (716
mg, 87%), m.p. 275 8C (dec.); nmax(KBr)/cmꢃ1 3414,
1712, 1590, 1521, 1497, 1442, 1277, 1187, 1093, 1014,
887, 832; dH(Me2SO-d6) 8.17 (2H, d, J 8.3, ArH), 7.84
(2H, d, J 8.3, ArH), 7.64 (4H, m, ArH), 7.23 (2H, d, J
8.5, ArH), 6.92 (2H, d, J 8.5, ArH), 4.81 (2H, t, J 1.8,
C5H4), 4.36 (2H, t, J 1.8, C5H4), 4.05 (5H, s, C5H5); m/z
475 (34%), 474 ([Mꢁ], 100), 472 (6), 279 (10), 278 (51),
255 (13), 277 (14), 198 (13), 197 (90), 169 (15), 168 (8),
150 (9), 141 (14), 121 (20). Anal. Found: [Mꢁ],
474.09225. Calc. for C29H22FeO3: [Mꢁ], 474.09183.
A solution of NaOH (0.12 g, 3.0 mmol) in water (10
cm3) was chilled to 0 8C in ice and to this was added 4-
ferrocenylphenol (0.30 g, 1.1 mmol). Methyl chlorofor-
mate (0.30 g, 3.2 mmol) was added slowly keeping the
temperature of the reaction mixture below 5 8C. After
stirring the mixture for 3 h at 0 8C, the solution was
acidified using dilute HCl. The solution was then
extracted with Et2O and after removing the solvent,
the residue was subjected to column chromatography,
elution with C6H14/CH2Cl2 (1:1) afforded the product.
Yield of 17 obtained was 0.19 g, 51%, m.p. 91 8C;
nmax(KBr)/cmꢃ1 3109, 3088, 3010, 2961, 2853, 1754,
1525, 1458, 1440, 1267, 1218, 1105, 1087, 1067, 1036,
1020, 1002, 951, 932, 888, 848, 823, 780, 740, 529, 500;
dH(CDCl3) 7.47 (2H, d, J 8.8, ArH), 7.11 (2H, d, J 8.8,
ArH), 4.61 (2H, t, J 1.8, C5H4), 4.32 (2H, t, J 1.8,
C5H4), 4.05 (5H, s, C5H5), 3.92 (3H, s, CH3); m/z 337
(33%), 336 ([Mꢁ], 100), 334 (11), 278 (32), 277 (49), 249
(25), 121 (51). Anal. Found: C, 64.4; H, 4.8%; [Mꢁ],
336.0445. Calc. for C18H16FeO3: C, 64.4; H, 4.8%;
[Mꢁ], 336.0444.
4.2.5. Representative synthesis of compounds in series 6
4.2.3. 4-Ferrocenylphenyl 4?-methoxycarbonyloxy-4-
biphenylcarboxylate (14)
4.2.5.1. 4-Ferrocenylphenyl
4?-propyloxy-4-biphenyl-
carboxylate (6, nꢂ3). Quantities: 4?-propyloxy-4-bi-
/
A solution of 4?-methoxycarbonyloxy-4-biphenylcar-
boxylic acid (835 mg, 3.1 mmol), 4-ferrocenylphenol
(853 mg, 3.1 mmol) and DMAP (125 mg, 1.0 mmol) in
anhydrous CH2Cl2 (15 cm3) was prepared under an
atmosphere of dry nitrogen. A solution of DCC (787
mg, 3.8 mmol) in anhydrous CH2Cl2 (40 cm3) was then
added over 1 min and the solution stirred at r.t. for 5
days. The solution was then filtered and the solvent
removed in vacuo. The crude product was purified by
flash column chromatography over silica gel using a
phenylcarboxylic acid (227 mg, 0.89 mmol), 4-ferroce-
nylphenol (255 mg, 0.92 mmol), DCC (244 mg, 1.18
mmol) and DMAP (51 mg, 0.42 mmol). The experi-
mental procedure was as described in Section 4.2.3. The
product 6 (nꢂ3) was obtained as yellow crystals and
/
was recrystallized from CH2Cl2/MeOH (85 mg, 18%),
m.p. 229 8C; nmax(KBr)/cmꢃ1 3080, 2968, 2934, 2878,
1723, 1603, 1522, 1497, 1473, 1454, 1403, 1298, 1271,
1200, 1170, 1104, 1072, 1029, 1014, 875, 826, 766, 717,
536; dH(CDCl3) 8.18 (2H, d, J 8.4, ArH), 7.64 (2H, d, J
8.4, ArH), 7.54 (2H, d, J 8.7, ArH), 7.47 (2H, d, J 8.6,
ArH), 7.10 (2H, d, J 8.6, ArH), 6.95 (2H, d, J 8.7, ArH),
4.57 (2H, t, J 1.8, C5H4), 4.26 (2H, t, J 1.8, C5H4), 4.01
(5H, s, C5H5), 3.92 (2H, t, J 6.6, OCH2), 1.79 (2H, m,
CH2), 1.00 (3H, m, CH3); m/z 518 (7%), 517 (38), 516
([Mꢁ], 100), 514 (7), 444 (5), 363 (7), 331 (7), 325 (6),
317 (18), 301 (7), 287 (5), 283 (6), 275 (9), 262 (6), 251
(12), 244 (7), 239 (22), 233 (11), 232 (12), 225 (10), 213
(24), 183 (16), 151 (63), 149 (14), 147 (9), 144 (7), 133
(28), 132 (18), 120 (13), 101 (30), 95 (15), 85 (18), 70 (22),
56 (13), 43 (11). Anal. Found: C, 73.8; H, 5.4%; [Mꢁ],
516.1385. Calc. for C32H28FeO3: C, 74.4; H, 5.5%;
[Mꢁ], 516.1388.
mixture of C6H14ꢀ
solvent was removed from the collected fractions and
the yellow solid was recrystallized from MeOHꢀCH2Cl2
/CH2Cl2 (1:1) as the eluent. The
/
(1.18 g, 72%) in the cold, m.p. (liquid crystal) 166,
194 8C; nmax(KBr)/cmꢃ1 3079, 2960, 2922, 2362, 1769,
1714, 1604, 1519, 1491, 1437, 1396, 1268, 1222, 1183,
1164, 1104, 1072, 1028, 1004, 933, 883, 810; dH(CDCl3)
8.28 (2H, d, J 8.5, ArH), 7.71 (2H, d, J 8.5, ArH), 7.67
(2H, d, J 8.7, ArH), 7.54 (2H, d, J 8.7, ArH), 7.31 (2H,
d, J 8.7, ArH) 7.17 (2H, d, J 8.6, ArH), 4.64 (2H, t, J
1.8, C5H4), 4.33 (2H, t, J 1.8, C5H4), 4.07 (5H, s, C5H5),
3.94 (3H, s, OCH3); dC(CDCl3) 156.2, 153.3, 151.1,
147.2, 139.9, 139.1, 132.8, 130.5, 129.2, 129.1, 86.8, 71.6,

60
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
4.2.6. 1-(4-Ferrocenylphenyl)ethyl 4?-
methoxycarbonyloxy-4-biphenylcarboxylate
(39). Anal. Found: C, 76.1; H, 6.9%; [Mꢁ], 614.2471.
Calc. for C39H42FeO3: C, 76.3; H, 6.9%; [Mꢁ],
614.2481.
Quantities:
4?-methoxycarbonyloxy-4-biphenylcar-
boxylic acid (433 mg, 1.59 mmol), 4-(1-hydro-
xyethyl)phenylferrocene (405 mg, 1.32 mmol), DMAP
(54 mg, 0.44 mmol), DCC (412 mg, 2.00 mmol). The
experimental procedure was as described in Section
4.2.8. 4-Hydroxymethylphenylferrocene
4.2.8.1. Step one. 4-Ferrocenylbenzoyl imidazolide. A
solution of 1,1?-carbonyldiimidazole (13.24 g, 81.7
mmol) in anhydrous THF (500 cm3) was added to a
solution of 4-ferrocenylbenzoic acid (5.00 g, 16.3 mmol)
in anhydrous THF (30 cm3) and the mixture stirred for
24 h at r.t. The solvent volume was reduced to ca. 20
cm3, and this solution was passed rapidly through a
silica gel column. Elution with Et2O afforded the
product which was obtained as a red solid (4.28 g,
4.2.3. The product was recrystallized from CH2Cl2ꢀ
/
MeOH in the cold (297 mg, 40%), m.p. 162 8C;
nmax(KBr)/cmꢃ1 3340, 2928, 1709, 1687, 1603, 1527,
1496, 1448, 1404, 1362, 1321, 1266, 1197, 1110, 1062,
1019, 997, 885, 856, 832, 774; dH(CDCl3) 8.24 (2H, d, J
8.5, ArH), 7.72 (2H, d, J 8.4, ArH), 7.71 (2H, d, J 8.6,
ArH), 7.56 (2H, d, J 8.2, ArH), 7.46 (2H, d, J 8.2, ArH),
7.36 (2H, d, J 8.7, ArH), 6.24 (1H, q, J 6.6, CH), 4.70
(2H, t, J 1.8, C5H4), 4.38 (2H, t, J 1.8, C5H4), 4.12 (5H,
s, C5H5), 4.01 (3H, t, J 6.6, OCH3), 1.78 (3H, d, J 6.6,
CH3); m/z 560 ([Mꢁ], 10%), 290 (8), 289 (22), 288 (100),
286 (9), 272 (19), 228 (23), 214 (5), 213 (14), 185 (12), 168
(6), 167 (10), 165 (7), 152 (5), 139 (9), 121 (9). Anal.
Found: [Mꢁ], 560.1278. Calc. for C33H28FeO5: [Mꢁ],
560.1285.
74%), m.p. 157ꢀ
158 8C; nmax(KBr)/cmꢃ1 2923, 2853,
/
1682, 1601, 1525, 1469, 1419, 1379, 1312, 1284, 1271,
1252, 1198, 1178, 1123, 1105, 1084, 1068, 1036, 1018,
969, 905, 882, 852, 836, 746, 694; dH(CDCl3) 8.07 (1H, s,
C3H3N2), 7.68 (2H, d, J 8.3, ArH), 7.55 (2H, d, J 8.3,
ArH), 7.51 (1H, s, C3H3N2), 7.12 (1H, s, C3H3N2), 4.68
(2H, t, J 1.8, C5H4), 4.39 (2H, t, J 1.8, C5H4), 4.01 (5H,
s, C5H5); m/z 356 ([Mꢁ], 13%), 307 (2), 306 (11), 261
(7), 168 (3), 140 (4), 139 (5). Anal. Found: [Mꢁ],
356.0622. Calc. for C20H16FeN2O: [Mꢁ], 356.0610.
4.2.7. Representative synthesis of compound in series 13
4.2.7.1. 1-(4-Ferrocenylphenyl)ethyl
4?-octyloxy-4-
biphenylcarboxylate (13, nꢂ8). A solution of 4?-octy-
/
4.2.8.2. Step two. Reduction of 4-ferrocenylbenzoyl imi-
dazolide. 4-Ferrocenylbenzoyl imidazolide (3.00 g, 8.4
mmol) was added to a solution of Et2O (250 cm3)
containing lithium aluminium hydride (LAH) (0.64 g,
16.8 mmol). The solution was stirred for 1 h at r.t. prior
to heating under reflux for 3 h. Excess LAH was
destroyed by the addition of EtOAc, and then by
loxy-4-biphenylcarboxylic acid (533 mg, 1.6 mmol), 4-
(1-hydroxyethyl)phenylferrocene (500 mg, 1.6 mmol)
and diethylazodicarboxylate (DEAD) (347 mg, 2.0
mmol) in anhydrous tetrahydrofuran (THF) (40 cm3)
was prepared under an atmosphere of dry Ar. A
solution of triphenylphosphine (522 mg, 2.0 mmol) in
anhydrous THF (5 cm3) was then slowly added and the
solution stirred for 2 weeks at r.t. The solvent was then
removed on a rotary evaporator, and the product
addition of a cold iceꢀ
mixture was filtered, extracted with Et2O (3ꢄ
/
water slurry. The reaction
100 cm3)
/
and the combined ether extracts were dried over
anhydrous Na2SO4. The solvent was removed in vacuo
and the residue passed through a column of silica gel,
recovered on a short silica gel column using CH2Cl2ꢀ
/
C6H14 (3:1) as the eluent. The initial orange band was
collected, the solvent was then removed and the residue
elution with CH2Cl2ꢀ
4-Hydroxybenzylferrocene was obtained as yellow crys-
tals (1.10 g, 45%), m.p. 109.5ꢀ
110 8C; nmax(KBr)/cmꢃ1
/
C6H14 (3:1) afforded the product.
recrystallized from CH2Cl2ꢀ
/
MeOH in the cold (240 mg,
92 8C; nmax(KBr)/cmꢃ1 2925, 2853,
24%), m.p. 89ꢀ
/
/
1709, 1609, 1524, 1495, 1472, 1395, 1339, 1280, 1246,
1187, 1118, 1102, 1058, 999, 829; dH(CDCl3) 8.16 (2H,
d, J 8.5, ArH), 7.65 (2H, d, J 8.5, ArH), 7.58 (2H, d, J
8.5, ArH), 7.50 (2H, t, J 8.5, ArH), 7.40 (2H, d, J 8.5,
ArH), 7.01 (2H, d, J 8.5, ArH), 6.19 (1H, q, J 6.5, CH),
4.64 (2H, t, J 1.8, C5H4), 4.33 (2H, t, J 1.8, C5H4), 4.09
(5H, s, C5H5), 4.02 (2H, t, J 6.6, OCH2), 1.82 (2H, m,
3287 (br), 2924, 1611, 1526, 1423, 1368, 1279, 1213,
1106, 1081, 1035, 1000, 886, 843, 804, 651, 537, 507, 482;
dH(CDCl3) 7.47 (2H, d, J 8.2, ArH), 7.28 (2H, d, J 8.2,
ArH), 4.66 (2H, d, J 5.5, CH2), 4.64 (2H, t, J 1.8, C5H4),
4.31 (2H, t, J 1.7, C5H4), 4.04 (5H, s, C5H5); m/z 293
(21%), 292 ([Mꢁ], 100), 290 (12), 227 (13), 154 (54), 153
(11), 152 (13), 121 (7). Anal. Found: C, 70.0; H, 5.8%;
[Mꢁ], 292.0546. Calc. for C17H16FeO: C, 69.9; H, 5.5%;
[Mꢁ], 292.0549.
CH2), 1.72 (3H, d, J 6.6, CH3), 1.31 (10H, m, 5ꢄCH2),
/
0.90 (3H, t, CH3); dC(CDCl3) 165.6, 159.2, 145.1, 139.1,
138.8, 132.0, 130.0, 128.1, 126.2, 126.1, 126.0, 114.7,
85.1, 72.5, 69.8, 68.5, 68.0, 66.4, 31.6, 29.2, 29.0, 25.8,
22.5, 22.0, 13.9; m/z 614 ([Mꢁ], 2%), 327 (14), 326 (59),
289 (38), 288 (67), 287 (5), 286 (17), 223 (5), 215 (28), 214
(100), 167 (18), 152 (9), 149 (7), 144 (9), 141 (6), 139 (8),
137 (8), 136 (5), 121 (18), 81 (23), 69 (54), 57 (32), 43
4.2.9. 4-Ferrocenylbenzyl 4?-methoxycarbonyloxy-4-
biphenylcarboxylate
A solution of 4?-methoxycarbonyloxy-4-biphenylcar-
boxylic acid (189 mg, 0.69 mmol), 4-hydroxybenzylfer-
rocene (200 mg, 0.68 mmol) and DMAP (44 mg, 0.15

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
/64
61
mmol) in anhydrous CH2Cl2 (40 cm3) was prepared
under an atmosphere of dry nitrogen. A solution of
DCC (189 mg, 0.92 mmol) in anhydrous CH2Cl2 (10
cm3) was then added over 1 min and the solution stirred
at r.t. for 5 days. The solution was then filtered and the
solvent removed in vacuo. The crude product was
purified by flash column chromatography over silica
gel using CH2Cl2 as the eluent. The solvent was removed
from the collected fractions and the yellow solid was
solution of DCC (650 mg, 3.15 mmol) in CH2Cl2 (30
cm3), and the reaction stirred at 25 8C for 16 h. The
N,N-dicyclohexylurea precipitate was filtered off and
the filtrate evaporated to dryness. The crude product
was subjected to chromatography on silica gel and
elution with C6H14ꢀ
Recrystallization from CH2Cl2ꢀ
/
CH2Cl2 (1:1) afforded the product.
MeOH in the cold gave
/
the product as a fluffy orange solid (737 mg, 41%), m.p.
165 8C; nmax(KBr)/cmꢃ1 2957, 2924, 2853, 1737, 1709,
1606, 1566, 1526, 1490, 1464, 1419, 1389, 1264, 1214,
1180, 1167, 1114, 1069, 1004, 859, 814, 771; dH(CDCl3)
8.14 (2H, d, J 8.4, ArH), 8.13 (2H, d, J 8.0, ArH), 7.70
(2H, d, J 8.5, ArH), 7.68 (2H, d, J 8.1, ArH), 7.60 (2H,
d, J 8.1, ArH), 7.34 (2H, d, J 8.1, ArH), 4.77 (2H, t, J
1.7, C5H4), 4.44 (2H, t, J 1.7, C5H4), 4.35 (2H, t, OCH2),
recrystallized from CH2Cl2ꢀ
/
MeOH (270 mg, 72%), m.p.
150 8C; nmax(KBr)/cmꢃ1 3934ꢀ
/3150 (br), 2949, 1760,
1709, 1611, 1526, 1497, 1440, 1377, 1269, 1217, 1175,
1103, 1011, 937, 823, 771; dH(CDCl3) 8.09 (2H, d, J 8.3,
ArH), 7.58 (2H, d, J 8.3, ArH), 7.55 (2H, d, J 8.3 ArH),
7.44 (2H, d, J 8.2, ArH), 7.32 (2H, d, J 8.1, ArH), 7.23
(2H, d, J 8.1, ArH), 5.29 (2H, s, CH2O), 4.58 (2H, t, J
1.8, C5H4), 4.26 (2H, t, J 1.8, C5H4), 3.98 (5H, s, C5H5),
3.87 (3H, s, OCH3); dC(CDCl3) 166.73, 154.60, 151.53,
145.09, 139.97, 138.40, 133.85, 130.73, 129.51, 128.85,
127.46, 126.70, 121.95, 85.25, 70.03, 69.45, 67.14, 66.99,
55.95; m/z 548 (9%), 547 (41), 546 ([Mꢁ], 100), 544 (7),
275 (10), 251 (7), 155 (7), 154 (45), 153 (6). Anal. Found:
C, 69.9; H, 5.0%; [Mꢁ], 546.1130. Calc. for
C32H26FeO5: C, 70.3; H, 4.8%; [Mꢁ], 546.1130.
4.07 (5H, s, C5H5), 1.82 (2H, m, CH2), 1.58ꢀ
/
1.20 (10H,
m, 5ꢄCH2), 0.89 (3H, m, CH3); dC(CDCl3) 166.97,
/
165.60, 151.53, 146.70, 145.11, 138.16, 138.81, 130.53,
129.76, 128.82, 127.41, 126.74, 126.19, 122.71, 83.39,
70.43, 70.31, 67.40, 65.63, 32.22, 29.69, 29.63, 29.16,
26.48, 23.08, 14.53; m/z 616 (11%), 615 (42), 614 ([Mꢁ],
100), 612 (7), 290 (9), 289 (40), 262 (20), 261 (97), 260
(5), 259 (7), 242 (6), 214 (5), 205 (6), 140 (5), 139 (8).
Anal. Found: C, 74.0; H, 6.8%; [Mꢁ], 614.2120. Calc.
for C38H38FeO4: C, 74.3; H, 6.7%; [Mꢁ], 614.2120.
4.2.10. Representative synthesis of compound in series 12
4.2.12. 4?-(2-Octyloxy)carbonyl-4-biphenyl 4-
ferrocenylbenzoate (18)
4.2.10.1. 4-Ferrocenylbenzyl
4?-octyloxy-4-biphenyl-
carboxlate (12, nꢂ8). Quantities: 4?-octyloxy-4-biphe-
/
A catalytic amount of DMAP was added to a solution
of 4-ferrocenylbenzoic acid (370 mg, 1.21 mmol) and 2-
octyl 4?-hydroxy-4-biphenylcarboxylate (355 mg, 1.21
mmol) in dry CH2Cl2 (150 cm3). To this was added a
solution of DCC (304 mg, 1.47 mmol) in CH2Cl2 (20
cm3). The reaction was stirred at r.t. for 16 h. The N,N-
dicyclohexylurea was filtered off and the filtrate was
then evaporated to dryness. The crude product was
subjected to chromatography on silica gel and elution
nylcarboxylic acid (224 mg, 0.69 mmol), 4-hydroxyben-
zylferrocene (200 mg, 0.68 mmol), DMAP (45 mg, 0.37
mmol), DCC (183 mg, 0.89 mmol) and CH2Cl2 (150
cm3). The experimental procedure was as described in
Section 4.2.9. The product was obtained as yellow
crystals recrystallized from CH2Cl2/MeOH in the cold
(224 mg, 54%), m.p. 91 8C; nmax(KBr)/cmꢃ1 3409, 3090,
2925, 2852, 1708, 1601, 1527, 1496, 1462, 1376, 1266,
1192, 1100, 1025, 997, 926, 887, 820, 767, 720, 633, 549,
495; dH(CDCl3) 8.12 (2H, d, J 8.3, ArH), 7.62 (2H, d, J
8.3, ArH), 7.55 (2H, d, J 8.6, ArH), 7.49 (2H, d, J 8.0,
ArH), 7.37 (2H, d, J 8.1, ArH), 6.98 (2H, d, J 8.6, ArH),
5.35 (2H, s, CH2O), 4.67 (2H, t, J 1.8, C5H4), 4.32 (2H,
t, J 1.8, C5H4), 4.04 (5H, s, C5H5), 4.00 (2H, t, J 6.6,
with C6H14ꢀ
orange solid recrystallized from MeOH (433 mg, 58%),
m.p. 119ꢀ
122 8C; nmax(KBr)/cmꢃ1 2926, 2872, 2854,
/
CH2Cl2 (1:1) afforded the product as an
/
1738, 1709, 1607, 1528, 1491, 1466, 1267, 1182, 1108,
1066; dH(CDCl3) 8.14 (2H, d, J 8.5, ArH), 8.13 (2H, d, J
8.4, ArH), 7.70 (2H, d, J 8.7, ArH), 7.68 (2H, d, J 8.0,
ArH), 7.61 (2H, d, J 8.3, ArH), 7.34 (2H, d, 8.7, ArH),
5.20 (1H, m, CH), 4.76 (2H, t, J 1.7, C5H4), 4.43 (2H, t,
J 1.7, C5H4), 4.07 (5H, s, C5H5), 1.92 (2H, m, CH2),
OCH2), 1.80 (2H, m, CH2), 1.47ꢀ
/
1.29 (10H, m, 5ꢄ
/
CH2), 0.88 (3H, s, CH3); m/z 602 (10%), 601 (43), 600
([Mꢁ], 100), 327 (6), 326 (27), 276 (5), 275 (7), 244 (9),
215 (13), 214 (83), 197 (7), 154 (23). Anal. Found: C,
76.0; H, 6.9%; [Mꢁ], 600.2321. Calc. for C38H40FeO3:
C, 76.0; H, 6.7%; [Mꢁ], 600.2324.
1.76ꢀ
/
1.20 (11H, m, CH3 and 4ꢄCH2), 0.89 (3H, t,
/
CH3); dC(CDCl3) 166.49, 165.60, 151.51, 146.69, 145.02,
138.22, 130.81, 130.51, 130.17, 128.82, 127.38, 126.75,
126.19, 122.70, 83.39, 72.24, 70.43, 70.32, 67.40, 36.51,
32.17, 29.60, 25.85, 23.02, 20.54, 14.50; m/z 616 (9%),
615 (39), 614 ([Mꢁ], 100), 612 (6), 366 (9), 328 (5), 316
(10), 290 (10), 289 (43), 287 (5), 266 (14), 262 (19), 261
(89), 260 (7), 259 (6), 250 (6), 243 (12), 214 (7), 205 (5),
139 (7). Anal. Found: C, 74.0; H, 6.2%; [Mꢁ], 614.2115.
Calc. for C38H38FeO4: C, 74.3; H, 6.2; [Mꢁ], 614.2120.
4.2.11. 4?-Octyloxycarbonyl-4-biphenyl 4-
ferrocenylbenzoate (17)
A catalytic amount of DMAP was added to a solution
of 4-ferrocenylbenzoic acid (700 mg, 2.94 mmol) and 1-
octyl 4-hydroxy-4-biphenylcarboxylate (756 mg, 2.94
mmol) in dry CH2Cl2 (300 cm3). To this was added a

62
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
4.2.13. 4?-Octyloxy-4-biphenyl 2-chloro-4-
ferrocenylbenzoate (22, nꢂ8)
(19), 295 (95), 261 (5), 204 (13), 203 (6), 202 (6), 186 (12),
185 (7), 139 (5), 43 (8). Anal. Found: C, 71.9; H, 6.6%;
[Mꢁ], 648.2087. Calc. for C39H41ClFeO3: C, 72.2; H,
6.4%; [Mꢁ], 648.2094.
/
A solution of 2-chloro-4-ferrocenylbenzoic acid (286
mg, 0.84 mmol), 4-hydroxy-4?-octyloxybiphenyl (250
mg, 0.84 mmol) and DMAP (34 mg, 0.28 mmol) in
anhydrous CH2Cl2 (100 cm3) was prepared under an
atmosphere of dry nitrogen. A solution of DCC (206
mg, 1.00 mmol) in anhydrous CH2Cl2 (30 cm3) was then
added over 1 min and the solution stirred at r.t. for 14
days. The solution was then filtered and the solvent
removed in vacuo. The crude product was purified by
flash column chromatography over silica gel using a
4.2.15. Representative synthesis of compounds in series
10
4.2.15.1. 4-(4?-Pentyloxy-4-biphenyloxycarbonyl)phenyl
4-ferrocenylbenzoate (10, nꢂ5). A solution of 4-ferro-
/
cenylbenzoic acid (407 mg, 1.3 mmol), 4?-pentyloxy-4-
biphenyl 4-hydroxybenzoate (500 mg, 1.3 mmol) and
DMAP (54 mg, 0.44 mmol) in anhydrous CH2Cl2 (200
cm3) was prepared under an atmosphere of dry nitrogen.
A solution of DCC (383 mg, 1.9 mmol) was then added
over 1 min, and the solution stirred at r.t. for 72 h. The
solution was then filtered and the solvent removed in
vacuo. The crude product was purified by flash column
mixture of C6H14ꢀ
solvent was removed from the collected fractions and
the red solid was recrystallized from CH2Cl2ꢀMeOH
/CH2Cl2 (1:1) as the eluent. The
/
(232 mg, 45%), m.p. 141 8C; nmax(KBr)/cmꢃ1 2923,
2853, 2362, 1741, 1600, 1548, 1495, 1474, 1408, 1388,
1289, 1249, 1202, 1153, 1092, 1030, 999, 906, 882, 843,
832, 804, 765, 686, 668, 524, 500; dH(CDCl3) 8.02 (1H,
d, J 8.2, ArH), 7.59 (3H, d, J 8.6, ArH), 7.51 (2H, d, J
8.6, ArH), 7.45 (1H, d, J 8.2, ArH), 7.29 (2H, d, J 8.5,
ArH), 6.97 (2H, d, J 8.7, ArH), 4.72 (2H, t, J 1.8,
C5H4), 4.44 (2H, t, J 1.8, C5H4), 4.08 (5H, s, C5H5), 4.00
chromatography over silica gel using C6H14ꢀ
(4:1) as the eluent. The product (nꢂ5) was obtained as
orange crystals recrystallized from CH2Cl2ꢀMeOH in
/CH2Cl2
/
/
the cold (601 mg, 68%), m.p. (liquid crystal) 178, 192,
291 8C (dec.); nmax(KBr)/cmꢃ1 3070, 2924, 2856, 2360,
1732, 1604, 1571, 1524, 1500, 1471, 1412, 1388, 1271,
1197, 1181, 1161, 1115, 1104, 1084, 1072, 1032, 1015,
920, 885; dH(CDCl3) 8.32 (2H, d, J 8.7, ArH), 8.13 (2H,
d, J 8.4, ArH), 7.60 (4H, d, J 8.2, ArH), 7.52 (2H, d, J
8.7, ArH), 7.41 (2H, d, J 8.7, ArH), 7.27 (2H, d, J 9.1,
ArH), 6.98 (2H, d, J 8.7, ArH), 4.77 (2H, d, J 1.8,
C5H4), 4.44 (2H, d, J 1.8, C5H4), 4.07 (5H, s, C5H5),
4.01 (2H, t, J 6.6, OCH2), 1.82 (2H, m, CH2), 1.44 (4H,
(2H, t, J 6.6, OCH2), 1.82 (2H, m, CH2), 1.49ꢀ
/
1.25
(10H, m, 5ꢄ
/
CH2), 0.91 (3H, t, CH3); m/z 622 (16%),
621 ([Mꢁ], 39), 620 (93), 618 (6), 366 (5), 325 (5), 323
(18), 322 (79), 320 (5), 316 (5), 297 (7), 296 (33), 295 (20),
294 (100), 266 (7), 211 (7), 204 (16), 203 (6), 200 (6), 186
(11), 185 (6), 181 (5), 139 (5). Anal. Found: C, 71.6; H,
6.1%; [Mꢁ], 620.17702. Calc. for C37H37ClFeO3: C,
71.6; H, 6.0%; [Mꢁ] 620.17806.
m, 2ꢄCH2), 0.95 (3H, m, CH3); dC(CDCl3) 165.01,
/
4.2.14. 4?-Decyloxy-4-biphenyl 2-chloro-4-
159.20, 155.73, 150.18, 147.04, 139.24, 133.11, 132.29,
130.87, 128.54, 128.19, 127.43, 126.34, 126.23, 122.51,
122.30, 115.22, 83.25, 70.51, 70.34, 68.50, 67.43, 29.41,
28.64, 22.91, 14.48; m/z 666 (12%), 665 (47), 664 ([Mꢁ],
100), 662 (7), 290 (11), 289 (47), 262 (13), 261 (62), 259
(5), 256 (12), 205 (7), 204 (20), 186 (28), 185 (7), 179 (12),
144 (15), 139 (5), 121 (5). Anal. Found: C, 73.8; H, 5.6%;
[Mꢁ], 664.1924. Calc. for C41H36FeO5: C, 74.1; H,
5.5%; [Mꢁ], 664.1912.
ferrocenylbenzoate (22, nꢂ10)
/
Quantities: 2-chloro-4-ferrocenylbenzoic acid (233
mg, 0.68 mmol), 4?-decyloxy-4-hydroxybiphenyl (223
mg, 0.68 mmol), DMAP (28 mg, 0.23 mmol) and DCC
(183 mg, 0.89 mmol). The experimental procedure was
as in Section 4.2.13. The product (nꢂ/10) was obtained
as red crystals recrystallized from CH2Cl2ꢀ
/
MeOH in the
cold (216 mg, 49%), m.p. 130 8C; nmax(KBr)/cmꢃ1 2921,
2865, 2363, 1741, 1599, 1547, 1494, 1474, 1467, 1387,
1289, 1267, 1251, 1202, 1166, 1094, 1032, 1014, 1001,
906, 882, 833, 805, 767, 686, 668, 500; dH(CDCl3) 8.03
(1H, d, J 8.2, ArH), 7.60 (3H, d, J 8.7, ArH), 7.51 (2H,
d, J 8.7, ArH), 7.45 (1H, d, J 8.2, ArH), 7.30 (2H, d, J
8.6, ArH), 6.97 (2H, d, J 8.7, ArH), 4.72 (2H, t, J 1.8,
C5H4), 4.44 (2H, t, J 1.8, C5H4), 4.08 (5H, s, C5H5), 4.00
4.2.16. 4?-Cyano-4-biphenyl 4?-ferrocenylbenzoate (19)
A solution of 4-ferrocenylbenzoic acid (513 mg, 1.7
mmol), 4-cyano-4?-hydroxybiphenyl (327 mg, 1.7 mmol)
and DMAP (20 mg, 0.17 mmol) in anhydrous CH2Cl2
(200 cm3) was prepared under an atmosphere of dry
nitrogen. A solution of DCC (415 mg, 2.0 mmol) in
anhydrous CH2Cl2 (60 cm3) was then added over 1 min
and the solution stirred at r.t. for 24 h. The solution was
then filtered and the solvent removed in vacuo. The
crude product was purified by flash column chromato-
(2H, t, J 6.6, OCH2), 1.81 (2H, m, CH2), 1.45ꢀ
/
1.29
(14H, m, 7ꢄCH2), 0.89 (3H, m, CH3); dC(CDCl3)
/
163.96, 158.82, 149.67, 146.69, 138.86, 135.00, 132.71,
132.34, 128.19, 128.12, 127.74, 125.40, 123.90, 121.87,
114.85, 81.58, 70.28, 69.98, 68.12, 67.02, 31.91, 29.57,
29.42, 29.33, 26.07, 22.69, 14.13; m/z 651 (15%), 650
(41), 649 (44), 648 ([Mꢁ], 100), 646 (7), 614 (5), 326 (5),
325 (27), 324 (17), 323 (76), 321 (5), 298 (7), 297 (31), 296
graphy over silica gel using a mixture of C6H14ꢀCH2Cl2
/
(1:1) as the eluent. The solvent was removed from the
collected fractions and the red solid was recrystallized
from CH2Cl2ꢀMeOH (780 mg, 96%), m.p. (liquid
/

C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ
/64
63
crystal) 238, 248 8C; nmax(KBr)/cmꢃ1 2940, 2926, 2857,
2366, 2354, 2229, 1720, 1600, 1520, 1491, 1417, 1269,
1229, 1183, 1069, 1006, 886, 851, 822, 800, 771, 703;
dH(CDCl3) 8.06 (2H, d, J 8.4, ArH), 7.68 (2H, d, J 8.6,
ArH), 7.63 (2H, d, J 8.6, ArH), 7.59 (2H, d, J 8.6, ArH),
7.53 (2H, d, J 8.5, ArH), 7.29 (2H, d, J 8.6, ArH), 4.70
(2H, t, J 1.8, C5H4), 4.37 (2H, t, J 1.8, C5H4), 4.00 (5H,
s, C5H5); dC(CDCl3) 165.12, 151.53, 146.43, 144.85,
136.81, 132.67, 130.40, 128.40, 127.71, 126.18, 125.79,
122.55, 118.90, 111.00, 82.91, 70.06, 69.91, 67.00; m/z
485 (6%), 484 (30), 483 ([Mꢁ], 100), 481 (6), 290 (6), 289
(26), 262 (18), 261 (92), 260 (6), 259 (6), 205 (9), 203 (5),
195 (7), 183 (7), 170 (6), 145 (6), 140 (10), 139 (19), 121
(7). Anal. Found: C, 74.5; H, 4.3; N, 2.9%; [Mꢁ],
483.09301. Calc. for C30H21FeNO2: C, 74.5; H, 4.4; N,
2.9%; [Mꢁ], 483.0917.
of C6H14ꢀCH2Cl2 (1:1) as the eluent. The solvent was
/
removed from the collected fractions and the orange
solid recrystallized from CH2Cl2/MeOH (259 mg, 78%),
m.p. 167ꢀ
/
168 8C; nmax(KBr)/cmꢃ1 3691ꢀ
3143 (br),
/
3100, 2980, 2946, 2886, 1780, 1746, 1660, 1617, 1531,
1506, 1471, 1403, 1283, 1206, 1180, 1154, 1086, 1017,
837; dH(CDCl3) 8.29 (2H, d, J 8.4, ArH), 7.71 (4H, t, J
8.7, ArH), 7.54 (2H, d, J 8.6, ArH), 7.26 (2H, d, J 8.5,
ArH), 7.17 (2H, d, J 8.6, ArH), 4.64 (2H, t, J 1.8,
C5H4), 4.42 (1H, d, J 7.1, CH), 4.33 (2H, t, J 1.8, C5H4),
4.08 (5H, s, C5H5), 2.26 (1H, m, CH), 1.47 (2H, m,
CH2), 1.16 (3H, d, J 6.8, CH3), 1.01 (3H, t, J 7.4, CH3);
dC(CDCl3) 168.39, 165.42, 150.93, 149.45, 145.60,
138.52, 137.51, 128.96, 128.74, 127.64, 127.47, 122.83,
122.21, 121.93, 85.21, 70.03, 69.38, 66.99, 63.01, 39.47,
25.56, 16.44, 11.31; m/z 608 (40%), 607 (41), 606 ([Mꢁ],
100), 604 (6), 572 (8), 571 (8), 570 (19), 558 (6), 474 (13),
473 (8), 331 (7), 329 (19), 278 (18), 277 (25), 249 (6), 198
(12), 197 (86), 169 (11), 168 (6), 141 (7), 121 (18). Anal.
Found: C, 69.9; H, 5.3%; [Mꢁ], 606.12593. Calc. for
C35H31ClFeO4: C, 69.4, H, 5.2%; [Mꢁ], 606.12603.
4.2.17. 4-(4?-Cyano-4-biphentyloxycarbonyl)phenyl 4-
ferrocenylbenzoate (20)
Quantities: 4-ferrocenylbenzoic acid (200 mg, 0.65
mmol), 4?-cyano-4-biphenyl 4-hydroxyphenylbenzoate
(250 mg, 0.65 mmol), DCC (188 mg, 0.91 mmol) and
DMAP (26 mg, 0.22 mmol). The experimental proce-
4.3. Crystal structure determination
dure as in Section 4.2.16. The product was an orangeꢀ
red solid (146 mg, 37%), m.p. (liquid crystal) 258, 304 8C
(dec.); nmax(KBr)/cmꢃ1 3500ꢀ
3000 (br), 2242, 1935,
1732, 1603, 1530, 1497, 1424, 1392, 1295, 1278, 1205,
1189, 1173, 1092, 1068, 1011, 897, 808, 776, 686;
dH(CDCl3) 8.32 (2H, d, J 8.7, ArH), 8.13 (2H, d, J
/
4.3.1. Crystal data for 14
/
Mrꢂ
/
532.35 g molꢃ1, size 0.08ꢄ
/
0.07ꢄ
/
0.05 mm3,
¯
triclinic, space group P1; aꢂ
/
9.0750(10), bꢂ
/
3
˚
˚
12.0290(10), cꢂ
296 K, Zꢂ2, rcalc
0.666 mmꢃ1, F(000)ꢂ
10), k (ꢃ15/14), l (ꢃ15/14), measured in the range
2.475U 526.528, 2422 independent reflections, Rint
0.0563, R1 obs 0.0637,
0.0466, wR2obs ꢂ0:1445; R1 all
wR2all ꢂ0:1508; goodness-of-fitꢂ
1.027.
/
12.522(2) A, Vꢂ
1.464 mg mꢃ3, m(Moꢀ
552, 2756 reflections in h (0/
/
1207.9(3) A , Tꢂ
/
/
ꢂ
/
/
Ka)ꢂ
/
8.5, ArH), 7.67ꢀ
/
7.61 (8H, m, ArH), 7.42ꢀ/7.36 (4H, m,
/
ArH), 4.77 (2H, t, J 1.8, C5H4), 4.45 (2H, t, J 1.8,
C5H4), 4.07 (5H, s, C5H5); dC(CDCl3) 165.02, 164.81,
155.90, 151.75, 147.12, 145.20, 137.42, 133.10, 132.34,
130.88, 128.87, 128.14, 127.09, 126.24, 122.90, 122.61,
119.30, 111.47, 83.21, 70.53, 70.34, 67.43; m/z 604
(39%), 603 ([Mꢁ], 91), 601 (6), 290 (12), 289 (54), 262
(20), 261 (100), 260 (8), 259 (7), 205 (10), 204 (18), 203
(7), 195 (19), 168 (10), 166 (6), 145 (7), 144 (29), 140 (13),
139 (18), 121 (26). Anal. Found: [Mꢁ], 603.11313. Calc.
for C37H25FeNO4: [Mꢁ], 603.11330.
/
/
/
/
ꢂ
/
ꢂ
/
ꢂ
/
/
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 186235 for compound 14.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
4.2.18. 4-[(1)-Chloro-(2)-methylbutyl carboxy]-4?-
biphenylcarboxy phenylferrocene
A solution of 4-ferrocenylphenyl 4?-hydroxy-4-biphe-
nylcarboxylate (260 mg, 0.55 mmol), 1-chloro-2-methyl-
butanecarboxylic acid (74 mg, 0.55 mmol) and DMAP
(22 mg, 0.18 mmol) in anhydrous CH2Cl2 (100 cm3) was
prepared under an atmosphere of dry nitrogen. A
solution of DCC (158 mg, 0.77 mmol) in anhydrous
CH2Cl2 (50 cm3) was then added over 1 min and the
solution stirred at r.t. for 2 weeks. TLC indicated that
the reaction was proceeding very slowly and thus the
solution was then stirred under reflux for another week.
The solution was then filtered and the solvent removed
in vacuo. The crude product was purified by flash
column chromatography over silica gel using a mixture
Cambridge CB2 1EZ, UK (Fax: ꢁ44-1223-336033; e-
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
/
Acknowledgements
The authors wish to thank the following persons for
technical assistance: H. Marchand (UPE) for general
technical assistance, Dr P. Boshoff (Cape Technikon,
Cape Town) for the mass spectrometric analyses, Dr R.
Sheets (Rhodes University, Grahamstown) for help with
use of the Linkam hotstage and polarizing microscope.

64
C. Imrie et al. / Journal of Organometallic Chemistry 665 (2003) 48ꢀ64
/
[6] J. March, Advanced Organic Chemistry, 4th ed., Wiley, New
York, 1992, p. 430.
One of the authors (C.I.) would especially like to thank
Professor J.R. Dilworth (University of Oxford) for
arranging help with the X-ray structure of compound
14. The National Research Foundation (Pretoria) and
the University of Port Elizabeth are gratefully acknowl-
edged for funding. The authors wish to extend a special
word of gratitude to Lancaster Synthesis (UK) for the
supply of phenylboronic acids.
[7] G.W. Gray, J.B. Hartley, B. Jones, J. Chem. Soc. (1955) 1412.
[8] (a) R. Deschenaux, J.-L. Marendaz, J. Chem. Soc. Chem.
Commun. (1991) 909;
(b) R. Deschenaux, J. Santiago, D. Guillon, B. Heinrich, J. Mater.
Chem. 4 (1994) 679;
(c) R. Deschenaux, I. Kosztics, J.-L. Marendaz, H. Stoeckli-
Evans, Chimia 47 (1993) 206;
(d) R. Deschenaux, J.-L. Marendaz, J. Santiago, Helv. Chim.
Acta 76 (1993) 865.
[9] C. Imrie, P. Engelbrecht, C. Loubser, C.W. McCleland, V.O.
Nyamori, R. Bogardi, D.C. Levendis, N. Tolom, J.L. van
Rooyen, J. Organomet. Chem. 645 (2002) 65.
References
[10] M.C. Tse, K.K. Cheung, M.C.W. Chun, C.M. Che, Chem.
Commun. (1998) 2295.
[1] J. Maltheˆte, J. Billard, Mol. Cryst. Liq. Cryst. 34 (1976) 117.
[2] C. Loubser, C. Imrie, P.H. van Rooyen, Adv. Mater. 5 (1993) 45.
[3] C. Loubser, C. Imrie, J. Chem. Soc. Perkin Trans 2 (1997) 399.
[4] C. Imrie, C. Loubser, P. Engelbrecht, C.W. McCleland, Appl.
Organomet. Chem. 15 (2001) 1.
[11] D. Gewirth, The HKL Manual, Written with the Cooperation of
the Program Authors, Z. Otwinowski and W. Miner, Yale
University, MA, 1995.
[12] G.M. Sheldrick, Acta Crystallogr. Sect. A 46 (1990) 467.
[13] G.M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University of Gottingen, Gottingen, Germany, 1996.
[5] C. Imrie, C. Loubser, C.W. McCleland, P. Engelbrecht, J. Chem.
Soc. Perkin Trans. 1 (1999) 2513.
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