The effect of low molecular weight organosiloxane substituents on mesophase formation and structure in non-symmetric nickel(II) complexes

Article abstract of DOI:10.1016/S0022-328X(97)00515-9

Organosiloxane groups have been used as components of metal-containing liquid crystals (metallomesogens). It has been found that the disiloxane unit aids mesophase formation, stabilising an enantiotropic smectic A phase over a wide temperature range. The

Full text of DOI:10.1016/S0022-328X(97)00515-9

Ž
.
Journal of Organometallic Chemistry 551 1998 299–311
The effect of low molecular weight organosiloxane substituents on
ž /
mesophase formation and structure in non-symmetric nickel II
1
complexes
)
Isabel M. Saez, Georg H. Mehl, Ekkehard Sinn, Peter Styring
Department of Chemistry, The UniÕersity of Hull, Hull, HU6 7RX, UK
Received 6 June 1997
Abstract
Ž
.
Organosiloxane groups have been used as components of metal-containing liquid crystals metallomesogens . It has been found that
the disiloxane unit aids mesophase formation, stabilising an enantiotropic smectic A phase over a wide temperature range. The overall
effect of an organodisiloxane unit is to lower the melting point relative to an alkyl substituted complex while increasing the clearing
temperature, or leaving it unchanged, and so increasing mesophase temperature range. A model for the mesophase is proposed based on
thermo-optical polarized light microscopy and small angle X-ray scattering studies. This proposes that weak nickel–nickel interactions,
which are observed in the solid state, are maintained in the mesophase. The unusual steric shape of the organosiloxane group stabilizes
the smectic A structure, allowing more efficient packing of the flexible chains. q 1998 Elsevier Science S.A.
Keywords: Organosiloxanes; Metallomesogens; Self-assembly; Thermo-optic properties
1. Introduction
Metal-containing liquid crystals metallomesogens
molecular structure to form segregated layers, assuming
that the molecule is composed of a polar aromatic core,
a non-polar hydrocarbon chain and a polar yet distinct
Ž
.
w x
w
x
have attracted considerable interest in recent years 1 .
PMDS terminal unit 3,4 . The phase behavior of these
low molar mass siloxanes is similar to that of polymeric
liquid crystalline siloxanes with respect to their solid
However, one of the major drawbacks that precludes the
application of metallomesogens in practical electro-optic
devices are the high melting points and clearing points
of the complexes. In organic liquid crystal chemistry,
w
x
and condensed phase behavior 3,4 .
We have shown that it is possible to synthesize
mono-activated, non-symmetric liquid crystalline co-
Ž
.
the use of a pentamethyldisiloxane PMDS terminal
group leads to significant decreases in the melting points
of the materials while, in general, the effect on the
clearing temperatures has been found to depend on the
w x
ordination complexes that can be easily polymerized 5
w
x
or hydrosilylated 5–7 . Using the latter methodology, it
is possible to obtain organosiloxane materials using a
wide variety of silicon-containing precursors. In this
paper the synthesis of an organosiloxane-terminated
nickel-containing metallomesogens, and analogous
complexes containing only hydrocarbon terminal chains,
will be discussed and their thermal and optical behavior
w
x
type of mesogenic group employed 2,3 . The result is a
wide liquid crystal phase range with a mesophase that is
stable at room temperature. This effect has been at-
tributed to aggregation of like segments within the
Ž
.
will be evaluated. Small angle X-ray scattering SAXS
studies have been undertaken in order to elucidate the
role of the organosiloxane unit in the molecular struc-
ture of the mesophase. A model for the mesophase
structure in these unique materials is also suggested.
)
Corresponding author. Tel: q44-0148-246-5409; fax: q44-
0148-246-6411; e-mail: p.styring@chem.hull.ac.uk.
1 Dedicated to Professor Peter Maitlis on the occasion of his 65th
birthday.
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

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I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
2. Results and discussion
regiospecific, only the linear isomer being formed by
w x
a-addition as observed previously 6 . However, in the
Ž
.
2.1. Synthesis
high field region ca. 0.0 ppm of 11 a number of
singlets were observed, some of them partially over-
lapped. The relative integration of this peak was deter-
mined as 12 protons which is consistent with the stoi-
chiometry of the pure material. We have interpreted this
splitting as an indication that the fully and partly bent
disiloxane conformers are present in solution together
with the conformer where the tetramethyldisiloxane
moiety is present in the fully extended form.
Ž
.
Ž .
1 was
4-Hydroxyphenyl dimethylaminoacrolein
prepared by the Vilsmeier–Arnold–Haack formylation
Ž
.
of commercial 4-hydroxyphenyl acetic acid as de-
w x
Ž
.
scribed by Lloyd et al. 8 . 2- 4-Decyloxyphenyl -N,N-
Ž .
dimethyl-1-aminoprop-1-en-3-al
2
was prepared
Ž
.
Scheme 1 by standard alkylation of 1 with 1-bromo-
dec-10-ene. Hydrolysis of 2 in strong, aqueous sodium
hydroxide followed by acidification yielded the desired
Ž
.
Ž
.
4-decenyloxyphenyl malonaldehyde 3b .
2.2. Thermo-optical properties
Ž .
The unsymmetrical ligands 6 were prepared by the
reaction of equimolar quantities of an appropriate
Ž .
phenylmalonaldehyde 3 , an appropriate salicylalde-
Ž .
The mesomorphic properties of the materials were
investigated by a combination of thermo-optical polar-
ized light microscopy using an Olympus BH-2 polarized
light microscope together with a Mettler FP52 microfur-
nace and FP5 temperature controller. The temperature
controller was calibrated to an accuracy of "0.18C in
the range 50–2858C. Phase transitions were confirmed
by differential scanning calorimetry DSC using a
Perkin Elmer DSC2 with TADS data acquisition system
at a scan rate of "108 miny1. The instrument was
hyde 5 and 1,2-diaminoethane in dichloromethane un-
Ž
.
der reflux with the separation of water Scheme 2 . The
1H NMR spectra of the ligands exhibit four unique
resonances in the region 13.5 to 7.5 ppm, which have
been assigned to the four different protons in the non-
symmetrical NNX OOX chelating core. The asymmetry of
the ligand is also reflected in the ethylenediamine re-
gion which shows two distinct resonances at around 3.8
and 3.65 ppm. The unsymmetrical, diamagnetic,
Ž
.
Ž .
Ž
.
Ž
square-planar nickel II complexes 7–9 were obtained
by the reaction of equimolar quantities of nickel acetate
tetrahydrate and an appropriate ligand 6 in refluxing
calibrated against pure indium metal Mps156.68C,
D Hs28.5 J gy1 9 . The transition temperatures of
the complexes studied are summarized in Table 1.
All three ligands, 6a–c, showed no mesomorphism,
melting directly to the isotropic liquid. This can be
rationalized by the fact that the ethylenediamine linking
group is saturated so the molecular core is unconjugated
and therefore each unsymmetrical half of the molecule
is free to rotate independently of the other. Furthermore,
unlike 1,3-diketonate ligands which are held together in
a rigid, mesogenic structure by intra-molecular hydro-
gen bonding, ligands 6 possess two protons in the
central cavity which results in steric crowding. Single
crystal X-ray diffraction studies on related ligands show
that there is an anti-conformation of the substitutions
.
w x
Ž .
methanol. Materials were characterized by standard
spectroscopic techniques IR; MS EI and FAB ; 1H
Ž
Ž
.
.
Ž
NMR and by elemental analysis. In some cases e.g.
9 , a methanol of crystallisation was observed in the
resulting complex.
.
Ž
.
The pentamethyldisiloxane-terminated complex 10
was prepared by the hydrosilylation reaction of 1.1
equivalents of 8 with pentamethylhydrodisiloxane in
toluene Scheme 3 using a 3–3.5% solution of plat-
inum 0 divinyltetramethyldisiloxane complex Kars-
Ž
.
Ž .
Ž
.
w
x
tedt’s catalyst in xylene Fluorochem as the catalyst at
room temperature, monitoring the disappearance of the
Si–H stretch at 2167 cmy1 in the IR spectrum 6 . The
w x
w
x
about the 1,2-diamino bridge 10 , a conformation not
conducive to mesomorphic behavior. However, addition
of a divalent metal ion has a templating effect, bringing
the two halves of the molecule together to form a rigid
central core with an NNX OOX donor set. This results in
product was obtained by recrystallisation from
Ž
.
dichloromethanermethanol 1:1 as red–brown needles
in 72% isolated yield. A similar procedure was used in
Ž
.
the preparation of the dimeric complex 11 using com-
plex 8 from ligand 6b and 1,1,3,3-tetramethyldihydro-
Ž
.
Ž
.
the appearance of a smectic A SmA mesophase in all
the complexes studied.
Ž
.
disiloxane TMDS in the molar ratio of 2:1, under the
same reaction conditions. Complex 11 was isolated as a
red–brown solid in 64% yield. The elemental analyses
are somewhat inaccurate in the siloxane materials. This
is common in these types of materials because of prob-
lems in combustion: it should be remembered that these
types of materials are often used as a precursor to
ceramics.
Ž
.
Complex 7 from 6a contains a terminal n-alkane
moiety and is therefore not activated towards hydrosily-
lation, but is a reference for the remaining complexes.
Complex 7 exhibits a single enantiotropic smectic A
Ž
.
SmA phase over the temperature range 193–2218C.
The nature of the liquid crystalline phase was deter-
mined using thermo-optical polarized light microscopy.
The smectic A phase was identified via its focal-conic
optical texture and the low viscosity of the material at
1
The H NMR spectra of the 10 and 11 were clean
and show that addition of the Si–H bond to the olefin is

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I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
301
Scheme 1. Synthesis of the 4-substituted phenyl malonaldehyde.
Ž
.
Ž
.
Scheme 2. General synthesis of the non-symmetric ligands and complexes. 3a: YsH. 3b: Y5CH2 5CH CH2 8O–. 5a: Xs –O CH2 8CH2CH3.
Ž
.
Ž
.
Ž
.
5b: X s –O CH2 8CH5CH2. 5c: X s H. 6a: Y s H; X s –O CH2 8CH2CH3. 6b: Y s H; X s –O CH2 8CH5CH2. 6c: Y s
CH2 5CH CH2 8O–; XsH. 7: YsH; Xs –O CH2 8CH2CH3. 8: YsH; Xs –O CH2 8CH5CH2. 9: YsCH2 5CH CH2 8O–; XsH.
Ž
.
Ž
.
Ž
.
Ž
.
Scheme 3. Hydrosilylation reactions of monomer 8.

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I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
Table 1
Mesomorphism in the liquid crystalline nickel complexes
Complex
X
Y
Tr8C
Ž
.
7
8
9
10
–O CH2 8CH2CH3
H
H
Cryst 193 SmA 221 Iso
Cryst 181 SmA 190 Iso
Cryst 209 Iso
Cryst1 162 Cryst2 184 SmA 240 Iso
Cryst 176 SmA 220 Iso
Ž
.
–O CH2 8CH5CH2
Ž
.
H
–O CH2 8CH5CH2
H
NrA
Ž
.
–O CH2 10SiMe2OSiMe3
(
)
5 dimer
NrA
Mesomorphism in the non-symmetrical nickel complexes.
Ž
.
10 . This results in an increase in the melting point of
that temperature. For a material of similar structure but
with a terminal alkenic group in the alkyl chain 8 ,
then the melting point is reduced slightly but the
mesophase is heavily destabilized with clearing occur-
ring at 1908C. This observation concurs with previous
experimental results for inorganic and organic materials
Ž .
Ž .
38C with respect to the parent complex 8 while the
clearing temperature is enhanced by 508C, to give a
smectic A phase over a 568C temperature range. This is
unexpected for the following reasons: Although for
simple organic liquid crystals, introduction of a PMDS
moiety tends to produce low melting point materials
relative to the alkane terminated analogues, the clearing
temperatures are also reduced 2 . Additionally, the
PMDS unit has little effect on the melting or clearing
points of the alkene terminated organic materials with
w
x
with liquid crystalline cores 11,12 .
Hydrosilylation of 8 with pentamethylhydrodisilox-
Ž
Ž .
w x
ane using Karstedt’s catalyst platinum 0 divinyltetra-
methyldisiloxane complex at room temperature gives
.
the complex with a terminally substituted PMDS group
Ž .
Ž .
Fig. 1. ORTEP diagrams of an unsymmetrical nickel complex showing a dimer formation in one unit cell and b long range nickel–nickel
interactions in the molecular structure.

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I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
303
long chain lengths. However, in the case of 10, while
the melting point is reduced relative to 7 but is rela-
tively unaffected relative to 8, the clearing temperature
is substantially increased relative to both.
In order to understand the structural influence of
reversing the substitution pattern on mesophase forma-
tion, we substituted the phenyl malonaldehyde sub-unit
in the 4-position while keeping the salicylaldehyde
sub-unit unsubstituted. The resulting alkene terminated
range interaction between the dimeric pairs. The molec-
Ž
.
ular packing diagram Fig. 1b shows that there is long
range correlation between nickel centers, brought about
by overlap of the d2z orbitals, to give an extended
molecular axis in the solid state. The individual
molecules within the dimer are inverted relative to each
other so that the different substituents are oriented at
1808 to each other. While the nickel atoms may be
superimposed on top of each other, the nitrogens in the
chelate core from one molecule are aligned with the
oxygens in the second molecule and vice versa as
Ž
.
complex 9 from 6c , which has the same molecular
formula as 8, showed no mesomorphism melting di-
rectly to the isotropic liquid at 2098C.
Ž
.
shown in the ORTEP diagram Fig. 1a . Similar molec-
ular packing is observed in the single crystal structures
of similar, symmetrical mesomorphic salicylaldamine
complexes that show nickel–nickel interactions over
considerable correlations lengths to give an extended
Hydrosilylation of two equivalents of 8 with di-
activated 1,1,3,3-tetramethyldihydrodisiloxane yielded
Ž
.
the dimeric TMDS complex 11 . The dimer shows both
a reduced melting point and a reduced clearing tempera-
Ž
.
w
x
ture relative to the monomeric PMDS complex 10 , to
give a smectic A phase with a 448C phase range. This is
again in contrast to the simple organic liquid crystalline
TMDS dimers where both the melting and clearing
temperature are significantly enhanced relative to the
metallic axis 13 . This may explain the high transition
temperatures observed in the liquid crystalline com-
plexes. Unfortunately, it has not yet been possible to
grow single crystals of X-ray quality for complexes
7–11.
w
x
PMDS monomers 3,4 .
The dramatic change in mesophase stability as a
result of a small modification in the molecular structure
may be attributable to the geometry of the central
chelating core. This is based on single crystal X-ray
diffraction studies of unsubstituted, non-symmetric
2.3. X-ray diffraction
While the complexes described in this paper show a
number of similarities to simple organic liquid crystals
there are some effects that are unique and may be
attributed to the presence of a transition metal center.
w
x
complexes 10 . The single crystal structure of complex
12, illustrates why the reversed complex 9 is non-
Ž .
mesomorphic. The presence of the 1,2-diaminoethane
bridge precludes conjugation of the molecular core so
that the two aromatic sections are not co-planar. Indeed,
there is a considerable twist of the phenyl malon-
aldehyde section away from the rest of the core. Molec-
ular modelling of a single molecule at 400 K using
2
Single crystal X-ray diffraction of the non-liquid crys-
Ž
.
talline complex 12
constant NVT molecular dynamics with 0.001 ps time
2
w
steps CERIUS ver 2.0 from Molecular Simulations
Ž
.x
MSI has been used to investigate the effects of substi-
tution of the phenyl malonaldehyde unit and also the
salicylaldehyde unit. Modelling was performed on sin-
gle molecules or weakly associated dimers on isolated
lattice sites. Initial molecular mechanics calculations
w
x
using the Universal 1.02 force field 14 were performed
to minimize the energy of the initial structure. Con-
straints were imposed around the metal core to prevent
deviations away from the observed crystal structure.
Being on an isolated lattice site, interactions of neigh-
boring molecules are neglected. The resultant simulated
structures were compared with the single crystal struc-
ture using the molecular similarity routine in Cerius2
and showed a low standard deviation around the chela-
tion core. The chelation core is almost bowlic in nature.
Substitution of the salicylaldehyde group gives a com-
plex in which the peripheral chain is largely co-linear
with the chelation core. Dimer formation gives an ex-
tended molecular geometry to form a rod-like structure
that is conducive to mesophase formation. Substitution
shows the molecules to form weakly associated dimers
w
x
in the solid state 10 . The observed unweighted and
weighted agreement factors were Rs0.062 and Rw s
0.063, respectively. Two discrete intermolecular nickel
to nickel distances are observed which also represent
the closest intermolecular contacts, with values of 3.3
˚
and 4.3 A. While these do not represent covalent bonds,
˚
they do represent significant interactions. The 3.3 A
separation represents the formation of weakly associated
˚
Ž
.
dimers Fig. 1a while the 4.3 A separation is a long-
2 The single crystal X-ray diffraction data for 12 have been
deposited with the Cambridge Crystallographic Data center and are
available as supplementary data.

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I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
of the phenyl malonaldehyde unit on the other hand
leads to a distorted shape that is accentuated in the
dimer. The peripheral chains are not co-linear giving a
distorted X-like structure that is not conducive to
mesophase formation. We propose that dimer formation
may be necessary for mesophase formation based on
by DSC measurements. Upon reaching the liquid-crys-
talline state the diffraction pattern coalesced into a
meridional maximum, which is indicative of some
macroscopic alignment of the material via interactions
with the surface of the capillary, diminishing with in-
creased temperature, indicative of a loss of the initially
obtained macroscopic ordering in the liquid crystalline
state.
Ž
.
information obtained from related oxovanadium IV
complexes. Infra red studies show the oxovanadium IV
Ž
.
˚
complexes to be completely monomeric with no evi-
dence of metal–metal or metal–axial oxygen interac-
The overall length of 8 was calculated as 27.2 A by
molecular dynamics simulation of a single molecule
2
w
x
Ž
.
Ž
.
tions in the solid state or in solution 15 . In contrast to
the nickel complexes, these materials show no meso-
morphism whatsoever, which therefore supports the as-
sumption that dimer formation is necessary to enhance
anisotropy. No X-ray data are available for these com-
plexes at the present time although in related 1,3-diketo-
nato complexes the closest intermolecular V . . . O con-
NVT, 400 K, 0.001 ps in Cerius MSI. . This as-
sumed that all sp3 hybridized atoms existed in an
anti-conformation about rotable bonds to give the fully
extended structure, taking no account of gauche bonds
or chain disorder. It is therefore difficult to rationalize
the observed d-spacing in the smectic A phase with a
monolayer structure. The high transition temperatures
may be rationalized via a degree of assembly within the
layers where weak nickel–nickel interactions are main-
tained after melting from the crystalline state to the
mesophase. The low viscosity observed under the opti-
cal polarising light microscope suggests that the
nickel–nickel interactions are present in the mesophase,
but are weak in order to allow for a fluid, dynamic
structure with free diffusion between layers. Above
1968C the material reached its isotropic liquid state
leading to the absence of small angle intensity maxima.
Cooling the sample lead to the formation of the
liquid crystalline phase at 1938C and the onset of crys-
tallization at 1798C. Whereas the d-spacings in the
smectic A phase were similar to those observed on
˚
tact is almost 8 A, which precludes dimer formation.
In order to further characterize the nature of the
smectic A phase and to derive a model for the assembly
of the molecules within that phase, complexes 7, 8 and
10 were investigated using small angle X-ray scattering
Ž
.
SAXS . High flux synchrotron radiation was employed
so that thermal degradation of the samples did not
become a problem. The experimental set-up of station
w
x
8.2 at Daresbury Laboratories 16,17 was used in order
to discount the presence of a SA; phase which is
characterized by an undulation of the layer planes: a
structural feature for which, in organic materials, peri-
˚
odicities greater than 100 A have been observed. How-
ever, in the materials reported here, this structural fea-
˚
˚
.
Ž
Ž .
ture could not observed for periodicities up to 230 A.
heating 26.4 4 A , the values for the crystalline phase
˚
.
Ž
Ž .
Samples were prepared as polycrystalline powders in
Lindemann tubes and kept at a controlled temperature.
This allowed for the recording of diffraction data whilst
performing temperature scans in the temperature inter-
val of interest. The selected experimental set-up was
limited to the recording of data relating to lattice param-
were found to be slightly higher 27.6 4 A . Addition-
ally, after the onset of supercooled crystallisation two
maxima were observed. One of them decreased in inten-
sity with decreasing temperature and could be detected
down to 1618C, corresponding to the smectic A phase
with a d-spacing of 26.4 4 A. This occurred within a
biphasic region having a width of 28C, with the crys-
talline state growing in to the smectic A phase.
˚
Ž .
˚
eters greater than 17.8 A and the use of wet rat tail
collagen as calibration standard leads to a systematic
w
x
Ž .
error of 3% in the observed d-spacings 18 . The sys-
tematic error is due to the sample to detector distance
For the alkane substituted complex 7 , an essentially
similar liquid crystalline phase structure could be ob-
w
x
calibration by a natural product 16,17 . Wide angle
served in the temperature interval of 190 to 2208C with
˚
˚
Ž .
A
Ž
.
Ž .
X-ray scattering WAXS data are not available at the
present time due to technical problems during data
collection, although we intend to continue these studies.
Data were collected for the alkenyl terminated com-
a d-spacing of 27.0 4 A, increasing to 27.6 4
preceding the isotropisation temperature. As the corre-
sponding molecular length obtained from molecular dy-
˚
namics is 27.5 A, it can be concluded that the smectic A
Ž .
plex 8 on heating in the temperature interval 180 to
phase is of similar structure to that proposed for 8.
Ž
.
2008C and on cooling between 200 and 1608C. For the
The pentamethylsiloxane substituted complex 10
crystalline state preceding the transition to the smectic
was studied over the temperature interval 180 to 2708C,
scanned at 38Crmin whilst recording diffraction data.
˚
Ž .
A phase, a d-spacing of 27.3 4 A was detected. After
˚
Ž .
passing through a short biphasic region, the smectic A
Two maxima were observed at d-spacings of 35.4 6 A
˚
˚
Ž .
Ž .
phase was reached, where a d-spacing of 26.4 4 A was
on melting to the smectic A phase and at 35.9 6 A
observed. The recorded transition temperature of 1808C
with a biphasic area up to 1828C is consistent with
results observed by optical polarising microscopy and
prior to isotropisation. The values of the d-spacings, are
slightly larger than that of the calculated maximum
˚
length of 32.2 A obtained by molecular dynamics,

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305
indicating that some overlap of the terminal siloxane
groups placed at the interfaces between the mesogenic
layers occurs. This observation is in agreement with
previous experimental results for cyanobiphenyl meso-
having a templating-like effect to aid layer formation. It
has been proposed that the organosiloxane end groups
self-organize through polar interactions to produce a
layered structure in the smectic A phase, separated into
organosiloxane, hydrocarbon and aromatic sub-regions
w
x
gens 3,4 .
w
x
2–4,6 . Calculations on isolated molecules of 10 and its
related dimeric structure to determine the electrostatic
potential over the surface of the molecule were per-
2.4. A model for the smectic A phase
Ž .
Ž
.
The alkane terminated complex 7 shows a d-spac-
formed in WebLab Viewer ver 2.0.1 MSI using the
˚
˚
ing of 27.6 A in the smectic A phase. The molecular
surface generator with a probe diameter of 1.4 A. The
length of 7 with a fully extended, all-trans peripheral
chain was calculated as 27.2 A using NVT molecular
dynamics at a simulation temperature of 400 K. A
electrostatic surfaces of a single molecule or a weakly
˚
associated dimer, which had previously been simulated
2
Ž
.
at 400 K using NVT molecular dynamics Cerius
nickel–nickel associated dimeric structure based on 7
reveal that the organosiloxane region, rather than being
a highly polar moiety, is considerably non-polar. Re-
gions of high electron density are clearly visible around
the chelation core and around the oxygen of the ether
side chain. An unexpected feature of the organosiloxane
region is the steric shape of the group, which exhibits a
kidney-like shape that allows for an off-center packing
of like-groups. This dissymmetry allows for the self-
organisation of the organosiloxane moieties into a sub-
layer as shown in Fig. 2, which in turn results in a high
degree of interdigitation, and allows for good space
filling. The resulting calculated layer spacing corre-
˚
would give an extended molecular length of ca. 37 A.
Allowing for interdigitation of the peripheral chains,
containing at least one gauche bond, gives a structure
with a calculated d-spacing which is in good agreement
with the experimental value. This classifies the phase as
Ž
.
a bilayer smectic A SmAd phase with respect to the
monomer. The interdigitation allows for good packing
of the peripheral chains, leaving the bulk free of spatial
voids. A similar model may be applied to the unsatu-
˚
Ž .
rated analogue 8 which shows a d-spacing of 26.4 A
in the smectic A phase, with a calculated molecular
˚
˚
Ž
.
length of ca. 36 A for the dimer. The depression of
sponds well with the experimental d-spacing 35.4 A
transition temperatures observed for the unsaturated
analogue is well known for simple organic liquid crys-
tals, especially where the unsaturated moiety is situated
at the chain terminus. For complexes 7 and 8 there is
only a 108C depression of the melting point on the
introduction of unsaturation. This may highlight the role
of the metal center on phase stabilisation although
further studies are required in this area. For all the
complexes investigated in this study the difference in
the melting points was found to be surprisingly small.
There is, however, a 308C depression of the clearing
temperature of 8 relative to 7. This can be directly
related to the presence of the terminal alkene, which can
cause packing difficult in the smectic A phase and so
destabilized the structure.
as shown in Fig. 2. It may be possible to attribute the
stabilisation of the mesophase to the increased ordering
of the molecules in the phase brought about by self-
organisation of the organosiloxane end groups, which
require increased energy for breakdown. Further studies
The inclusion of a pentamethyldisiloxane end group
Ž
.
10 has little effect on the melting point of the complex
relative to complex 8, but shows a similar depression
Ž .
Ž
.
108C relative to the saturated analogue 7 . However,
the clearing point of 10 is increased significantly rela-
tive to both complexes 7 and 8. This effect is unusual in
pentamethyldisiloxane terminated materials. A model to
explain such phase behaviour is shown in Fig. 2. An
intercalated phase structure of the SmAd-type, based on
pairing the of single molecules of 10, would require a
2
˚
Ž
.
d-spacing of 41 A in the fully extended form Cerius .
The observed stabilisation of the smectic A phase of the
organosiloxane containing material with respect to the
alkyl or alkenyl terminated mesogen may be attributable
to the existence of weak nickel–nickel interactions,
Fig. 2. A model for the smectic A phase in the PMDS terminated
Ž
.
complex. Nickel atoms are shown as black circles v . The larger
grey circles represent the off-set PDMS units.

(
)
306
I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
Ž
.
Ž
.
are in progress on a range of different materials in an
attempt to fully clarify the phase structure.
C10 H19 Br 3.26 g, 14.9 mmol in butanone 200 ml
Ž
.
were heated to reflux 20 h , protected from moisture
with a calcium chloride guard tube. The resulting sus-
pension was filtered off and the solution evaporated to
dryness to yield a white solid. The solid was purified by
We propose that the existence of dimeric molecules
is necessary to support mesophase formation as the
monomeric molecules themselves do not possess a suf-
ficiently mesogenic structure, being substituted on only
one side of the central chelation core. We would point
Ž
column chromatography flash grade silica gel; elution
.
with CH2Cl2rTHF 4r1 , to yield 2 as a colorless syrup
Ž
.
Ž
.
Ž
.
to the loss of mesomorphism in the oxovanadium IV
Rf s0.54 . Yields4.89 g 94% .
w
x
complexes discussed earlier 15 as evidence for this.
The differences in melting points are brought about as a
direct result of the packing abilities of the terminal
moieties and are consistent with previously reported
systems. The differences in clearing temperatures how-
ever, are reasonably unique. In simple cyanobiphenyl
(
)
( )
3.2. 4-Dec-9-enyloxy phenyl malonaldehyde, 3a
Ž
.
A solution of sodium hydroxide 7.42 g, 185 mmol
in water 22 ml was added to a solution of 2 4.89 g,
Ž
.
Ž
.
Ž
.
14.84 mmol in ethanol 100 ml and the two layer
mixture heated gently to reflux for 3 h. The solution
was cooled down to room temperature and the ethanol
evaporated in vacuo until only water remained. The
white solid so formed was filtered off, suspended in
water 100 ml and the strongly alkaline solution was
neutralized with 10N HCl until ca. pH 3. The resulting
white solid was filtered off, washed repeatedly with
water, dissolved in CH2Cl2 and the organic layer dried
over MgSO4. The solvent was evaporated and the white
solid produced was recrystallised form petroleum ether.
w
x
liquid crystal systems 2–4 , inclusion of a pentamethyl-
disiloxane unit tends to give a large depression of the
melting and clearing temperatures with respect to the
alkyl-terminated material. The melting and clearing
points of the PMDS-terminated cyanobiphenyls are
however relatively unchanged with respect to the
alkenyl-terminated analogues. However, for the material
reported here, the clearing temperature is significantly
increased on the inclusion of a pentamethyldisiloxane
unit relative to both the alkyl and alkenyl terminated
analogues. We therefore propose that the clearing tem-
perature corresponds to the breakdown of the dimeric
nickel–nickel interactions to form discreet monomeric
units. It should be pointed out that the model is consis-
tent with the assembly of the sub-units in terms of their
associated ‘philicities’.
Ž
.
Ž
.
Yields3.18 g 71% .
1
Ž
.
Ž
.
Ž
H NMR CDCl3 : d 14.30 s, 1H, OH ; 8.70 s, 2H,
.
Ž
.
CHO, 5CH–OH ; 7.17, 6.92 AB q, 4H, aromatic ;
Ž Ž . Ž
.
Ž
.
5.81 d Jtrans s17 Hz d Jcis s10 Hz t Jfg s7 Hz ,
e
.
Ž Ž
.
.
1H, CH2 5C H ; 4.99 d Jtrans s17 Hz m, 1H, H ;
Ž Ž Ž Ž
.
.
.
4.93 d Jcis s10 Hz m, 1H, Hd ; 3.87 t Js7 Hz ,
.
Ž
.
.
Ž
2H, C H2O ; 2.04 m, 2H, C H2–CH5 ; 1.73 m, 2H,
.
Ž
Ž
. .
C H2–CH2–O ; 1.30 m, 10H, CH2
5
(
)
( )
3. Experimental
3.3. 4- Decyloxy phenol, 4a
Ž
.
Solvents were dried over appropriate drying agents
and distilled prior use. Nickel acetate tetrahydrate was
purchased from Aldrich and used as received. All silox-
ane materials, including Karstedt’s catalyst were pur-
chased from Fluorochem.
Hydroquinone 37.65 g, 342 mmol and 1-bromode-
Ž
.
cane 23.65 ml, 114 mmol were dissolved in ethanol
150 ml with warming under a nitrogen atmosphere.
The solution was heated under reflux and a solution of
potassium hydroxide 6.83 g, 121 mmol in water 20
ml was added dropwise over 1 h. The resulting suspen-
sion was heated under reflux 3 h then poured on to
water 500 ml and extracted with ether 3=100 ml .
The combined extracts were dried MgSO4 , evaporated
in vacuo and the residue extracted with heptane 300
Ž
.
Ž
.
Ž
.
Infrared spectra were recorded on a Perkin–Elmer
783 spectrometer. NMR spectra were recorded on a Jeol
Ž
.
Ž1
.
Ž
.
Ž
.
JNM-GX spectrometer H, 270 MHz ; chemical shifts
Ž .
Ž
.
are reported in parts per million d with reference to
Ž
internal SiMe4 or residual protonated species of the
deuterated solvent used for 1H analysis. Elemental anal-
ysis was performed on a Fisons Instruments Carlo Erba
EA 1108 CHN analyzer using acetanilide as the refer-
ence standard. V2O5 was added to aid combustion in a
number of cases. Mass spectra were recorded on a
.
Ž
Ž
ml . Cooling afforded a first crop of the phenol 10.31
g . The remaining material was chromatographed flash
.
grade silica gel, petroleum ether 40–608Crdiethyl ether
.
Ž
.
3r2 . 2 was isolated as white plates Rf s0.57 . Com-
Ž
.
bined yields15.69 g 55% . Mps548C.
1
Ž
Ž
.
Ž
.
Ž
Finnigan 1020 GC-MS spectrometer electron ionisation
H NMR CDCl3 :d 6.76 m, 4H, aromatic ; 4.63 s,
Ž Ž
.
Ž
.
.
Ž
.
Ž
moder70 eV and on a Kratos MS80 spectrometer fast
1H, OH ; 3.88 t Js7 Hz , 2H, C H2O ; 1.74 m, 2H,
.
.
Ž
. .
Ž Ž
.
atom bombardment moderNOBA matrix .
C H2–CH2O ; 1.30 m, H, C H2 , 0.70 t Js7 Hz ,
7
.
3H, C H3 .
(
)
3.1. 2- 4-Dec-9-enyloxyphenyl -N,N-dimethyl-1-
( )
(
)
(
)
aminoprop-1-en-3-al, 2
3.4. 4- Dec-9-en-yloxy phenol 4b
Ž
.
Ž . Ž
4-Hydroxyphenyl dimethylaminoacrolein 1 3.00
The synthetic procedure was as described for 4a
above using the following quantities: Hydroquinone
.
Ž
.
g, 15.6 mmol , K2CO3 2.49 g, 18.0 mmol and

(
)
I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
307
Ž
.
Ž
Ž
.
Ž
.
37.65 g, 342 mmol ; dec-9-enylbromide 25 g, 114
0.74 g, 5 mmol in dichloromethane 300 ml . A white
precipitate formed immediately. The salicylaldehyde 5a
.
Ž
.
mmol ; potassium hydroxide 6.83 g, 121 mmol . Yield
s15.61 g 55% . Mps548C.
Ž
.
Ž
.
1.391 g, 5 mmol was added and the resulting suspen-
1
Ž
.
Ž
.
Ž
.
H NMR CDCl3 : d 6.78 m, 4H, aromatic ; 5.81
sion stirred at room temperature 18 h and then re-
fluxed using a Dean–Stark apparatus until a clear yel-
Ž Ž
.
Ž Ž
Ž
. Ž
.
d Jtrans s17 Hz d Jcis s10 Hz t Jfg s7 Hz , 1H,
.
.
.
.
Ž
.
CH2 5C H ; 4.99 d Jtrans s17 Hz m, 1H, He ; 4.93
low solution was obtained 6 h . The yellow solution
was evaporated in vacuo and the residue purified by
column chromatography flash grade silica gel,
Ž Ž
.
.
Ž
d Jcis s10 Hz m, 1H, Hd ; 4.63 s, 1H, OH ; 3.89
Ž Ž
.
.
Ž
.
Ž
t Js7 Hz , 2H, C H2O ; 2.04 m, 2H, C H2–CH5 ;
Ž
.
Ž
Ž
. .
.
1.73 m, 2H, C H2–CH2–O ; 1.30 m, 10H, C H2 5 .
Cl2CH2rTHF, 4r1 . The band with Rf s0.83 yielded
Ž
.
symmetrical salen derivative 0.369 g, 51% . The band
with Rf s0.66 was collected and the product recrystal-
lized from Cl2CH2rMeOH to yield yellow microcrys-
(
)
( )
3.5. 2-Hydroxy-5- decyloxy benzaldehyde, 5a
Ž
.
SnCl4 0.52 ml, 4.53 mmol was added to a solution
Ž
.
tals of 6a. Yields0.616 g 55% . The percentage
Ž
.
of 4-decyloxyphenol 11.35 g, 45.3 mmol in sodium
dried, degassed toluene 250 ml under a dry nitrogen
atmosphere. Tri-n-butylamine 4.30 ml, 18.13 mmol
was added at room temperature. The solution turned
yellow and was stirred for 1 h before paraformaldehyde
yields are based on the statistical maximum theoretical
Ž
.
Ž
yields: 50% maximum for the unsymmetrical ligand
and 25% maximum for the salen ligand in the reaction
mixture 6 .
Microanalysis: Calcd for C28 H38O3N2: C, 74.64; H,
8.49; N, 6.21. Found: C, 74.46; H, 8.74; N, 6.11.
Ž
.
.
w x
Ž
. Ž
.
BDH 2.99 g, 100 mmol was added and the yellow
Ž
.
suspension heated to 1058C 3 h . The brown solution
q
q
Ž
.
Ž
.
Ž
.
Ž
MS EI : mrz 451 M 450 M y1 ; 421 M y
Ž
was cooled, poured onto saturated aqueous NaCl 200
ml and acidified to pH 2 with 10% HCl. The product
was extracted with ether 3=100 ml and the combined
organic layers dried MgSO4 and evaporated. The
.
CO .
.
1
Ž
.
Ž
.
Ž
H NMR CDCl3 : d 12.57 s, 1H, OH ; 10.60 m
Ž Ž
Ž
.
.
.
.
broad, 1H, NH ; 9.60 d Js4 Hz , 1H, C HO ; 8.43
Ž
.
Ž
.
Ž
s, 1H, C H5N ; 7.45-6.87 m, 9H, aromatic C6 H5, Ha,
Ž Ž
Ž
residue was purified by column chromatography flash
.
.
.
Hb, Hc , NC H5C ; 4.01 t Js7 Hz , 2H, C H2O ;
grade silica gel; petroleum ether 40–608Crdiethyl ether,
Ž
Ž
.
Ž
Ž
.
3.93 m, 2H, C H2–N5CH ; 3.78 m, 2H, C H2–NH ;
.
3r2 . The title compound 5a was isolated as a yellow
.
Ž
. .
1.85 m, 2H, C H2–CH2–O ; 1.40 m, 14H, C H2 7 ;
Ž Ž
Ž
.
Ž
.
oil Rf s0.62 . Yields3.72 g 29% .
1
.
.
0.95 t Js7 Hz , 3H, CH3 .
Ž
.
Ž
.
Ž
H NMR CDCl3 : d 10.64 s, 1H, OH ; 9.85 s,
.
Ž Ž
.
Ž
.
1H, C HO ; 7.13 d Jab s9 Hz d Jbc s3 Hz , 1H,
(
)
3.8. 8- 3-Dec-9-enyloxy-6-hydroxyphenyl -2-phenyl-
4,7-diazocta-2,7-dien-1-al, 6b
.
Ž Ž Ž Ž
.
.
.
Hb ; 7.00 t Js3 Hz , 1H, Hc ; 6.92 d Js9 Hz ,
(
)
.
Ž Ž
.
.
Ž
1H, Ha ; 3.94 t Js7 Hz , 3H, C H2O ; 1.78 m, 2H,
Ž
.
1,2-Diaminoethane 0.2 g, 3.36 mmol was added to
a vigorously stirred solution of 2-phenyl-3-hydroxypro-
.
.
Ž
Ž
. . Ž Ž
C H2–CH2–O ; 1.60 m, 14H, CH2 ; 0.88 t Js7
7
.
Hz , 3H, CH3 .
Ž
.
Ž
.
penal 0.498 g, 3.36 mmol in CH2Cl2 300 ml . A
white precipitate formed immediately. 2-Hydroxy-5-
(
)
( )
3.6. 2-Hydroxy-5- dec-9-enyloxy benzaldehyde, 5b
Ž
.
Ž
.
dec-9-enyloxy benzaldehyde 0.93 g, 3.36 mmol was
added and the yellow suspension was stirred at room
The preparation was as described above for com-
Ž
pound 5a using the following quantities: SnCl4 0.27
ml, 2.33 mmol , 4- dec-9-enyloxy phenol 5.80 g, 23.33
mmol , toluene 250 ml , tri-n-butylamine 2.22 ml,
9.34 mmol , paraformaldehyde 1.54 g, 51 mmol . The
Ž
.
Ž
.
temperature 18 h and then heated under reflux 5 h
.
Ž
.
Ž
using a Dean–Stark apparatus protected from moisture
with a calcium chloride guard tube. The yellow solution
was evaporated in vacuo and the residue purified by
.
Ž
.
Ž
.
Ž
.
Ž
title compound 5b was isolated as a yellow oil Rf s
Ž
column chromatography flash grade silica gel;
.
Ž
.
0.62 . Yields2.44 g 38% .
.
CH2Cl2rTHF, 4r1 . The band with Rf s0.76 yielded
1
Ž
.
Ž
.
Ž
H NMR CDCl3 : d 10.91 s, 1H, OH ; 9.85 s,
Ž
the symmetrical by-product 1,6-di 3-dec-9-enyloxy-6-
.
Ž Ž
.
.
Ž
1H, C HO ; 7.32 d Js3 Hz , 1H, Ha ; 7.24 m, 1H,
.
hydroxyphenyl -2,5-diazahexa-1,5-diene after recrys-
.
Ž Ž Ž Ž
.
.
.
Hb ; 7.0 d Js9 Hz , 1H, Hc ; 5.81 d Jtrans s17 Hz
Ž
.
tallisation from ethanol yields0.19 g, 40% . The band
with Rf s0.50 was collected and the product recrys-
tallised from ethanol to yield bright yellow crystals of
6b. Yields0.46 g 61% 6 .
Ž
. Ž
.
.
d Jcis s10 Hz t Jfg s7 Hz , 1H, CH2 5C H ; 4.99
Ž Ž Ž Ž
.
.
.
d Jtrans s17 Hz m, 1H, He ; 4.93 d Jcis s10 Hz
.
Ž Ž
.
.
Ž
m, 1H, Hd ; 3.87 t Js7 Hz , 2H, C H2O ; 2.04 m,
Ž
. w x
.
Ž
.
2H, C H2–CHs ; 1.73 m, 2H, C H2–CH2–O ; 1.30
Micro analysis: Calc. for C28 H36O3N2: C, 74.97; H,
Ž
Ž
. .
m, 10H, C H2
.
5
8.08; N, 6.24. Found: C, 74.66; H, 8.12; N, 6.21.
1
q
q
Ž
.
Ž
.
Ž
.
MS EI : mrz 448 M ; 420 M yCO . H NMR
(
)
3.7. 8- 3-Decyloxy-6-hydroxyphenyl -2-phenyl-4,7-di-
azocta-2,7-dien-1-al, 6a
Ž
.
Ž
.
Ž
CDCl3 : d 12.45 s, 1H, OH ; 10.48 m broad, 1H,
Ž Ž
(
)
.
.
.
Ž
NH ; 9.47 d Js4 Hz , 1H, C HO ; 8.31 s, 1H,
Ž
.
.
Ž
1,2-Diaminoethane 0.33 ml, 5 mmol was added to a
vigorously stirred solution of phenylmalonaldehyde
C H5N ; 7.30-6.72 m, 9H, aromatic C6 H5, Ha, Hb,
Ž Ž
.
.
Ž
Hc , NC H5C ; 5.81 d Jtrans s17 Hz d Jcis s10

(
)
308
I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
. Ž
.
.
Ž Ž
Ž
.
Ž
Hz t Jfg s7 Hz , 1H, CH2 sC H ; 4.99 d Jtrans s17
solution of 6b 0.350 g, 0.78 mmol in methanol 30
.
.
Ž Ž
.
.
.
Hz m, 1H, He ; 4.93 d Jcis s10 Hz m, 1H, Hd ;
ml which was heated to reflux. The red solution ob-
Ž Ž
.
.
Ž
Ž
Ž
.
3.88 t Js7 Hz , 2H, C H2O ; 3.81 m, 2H, C H2–
tained was heated under reflux 1 h and on cooling to
room temperature produced red–brown needles which
were filtered off, dried and recrystallized from methanol.
.
Ž
.
N5CH ; 3.65 m, 2H, C H2–NH ; 2.04 m, 2H, C H2–
.
Ž
.
Ž
CH5 ; 1.70 m, 2H, C H2–CH2–O ; 1.30 m, 10H,
. .
Ž
Ž
.
C H2
.
Yields0.355 g 90% .
5
Mesomorphism: Cryst 181 SmA 190 Iso 8C.
Microanalysis: Calcd for C28 H34O3N2 Ni: C, 66.56;
H, 6.77; N, 5.54. Found: C, 66.47; H, 6.65; N, 5.46.
(
)
(
3.9. 8- 2-Hydroxyphenyl -2- 4-dec-9-enyloxy-6-hy-
droxyphenyl -4,7-diazocta-2,7-dien-1-al, 6c
)
( )
q
q
Ž
.
Ž
.
Ž
.
MS EI : mrz 504 M y1 ; 365 M yC10 H19 .
The reversed ligand was prepared as described previ-
ously for 6ac from 3b 1.209 g; 4.0 mmol , 1,2-di-
Ž
Molecular weight determination osmometry in
Ž
.
.
Ž
CHCl3 : Calcd for C28 H3y4O1 3N2 Ni: 505.24; Found: 567.
Ž
.
aminoethane 0.26 ml; 4.0 mmol and salicylaldehyde
. Ž
.
Ž
IR KBr disc, yrcm : 1609 vs, sharp; C5N,
Ž
.
Aldrich 0.41 ml; 4.0 mmol in CH2Cl2. Yields0.155
.
C5O and C5C–N coordinated .
Ž
.
1
g 17% .
Microanalysis: Calcd for C28 H36O3N2: C, 74.97; H,
8.08; N, 6.24. Found: C, 75.33; H, 8.23; N, 6.23.
Ž
.
Ž
H NMR CDCl3 : d 7.4-7.0 m, 8H; aromatic C6 H5,
.
Ž
.
HC5N, HC5O and NC H5C ; 6.91 m, 2H, Ha,Hb ;
Ž Ž . Ž
Ž
.
6.48 m, 1H, Hc ; 5.81 d Jtrans s17 Hz d Jcis s10
q
Ž
.
Ž
.
MS EI : mrz 448 M .
. Ž Ž Ž
.
.
Hz t Jfg s7 Hz , 1H, CH2 5C H ; 4.99 d Jtrans s17
1
Ž
.
Ž
.
Ž
H NMR CDCl3 : d 12.95 s, 1H, OH ; 10.37 m
Ž Ž
.
.
Ž Ž
.
.
.
Hz m, 1H, He ; 4.93 d Jcis s10 Hz m, 1H, Hd ; 3.79
.
.
.
.
broad, 1H, NH ; 9.40 d Js4 Hz , 1H, C HO ; 8.36
Ž Ž
Ž
.
.
Ž
t Js7 Hz , 2H, C H2O ; 3.34 m, 4H, NC H2 ; 2.04
Ž
Ž
s, 1H, C H5N ; 7.40-6.78 m, 9H, aromatic C6 H4,
Ž Ž . Ž . Ž
.
Ž
.
m, 2H, C H2–CH5 ; 1.70 m, 2H, C H2–CH2–O ;
. .
.
NC H5C ; 5.82 d Jtrans s17 Hz d Jcis s10 Hz t Jfg
Ž
Ž
1.30 m, 10H, C H2
.
5
.
.
.
Ž Ž
.
s7 Hz , 1H, CH2 5C H ; 4.99 d Jtrans s17 Hz m,
Ž Ž Ž Ž
.
.
1H, He ; 4.93 d Jcis s10 Hz m, 1H, Hd ; 3.91 t Js
(
)
(
3.12. 8- 2-Hydroxyphenyl -2- 4-dec-9-enyloxy-6-hy-
]( ) ( )
.
.
Ž
.
7 Hz , 2H, C H2O ; 3.79 m, 2H, C H2–NsCH ; 3.62
)
droxyphenyl -4,7-diazocta-1,3,7-trienato 2- nickel II ,
( )
Ž
.
Ž
.
Ž
m, 2H, C H2–NH ; 2.04 m, 2H, C H2–CH5 ; 1.70 m,
. .
9
.
Ž
Ž
2H, C H2–CH2–O ; 1.30 m, 10H, C H2
.
5
Ž .
Ž
.
Nickel II acetate tetrahydrate 24.8 mg; 0.1 mmol
was added to a refluxing solution of 6c 44.8 mg; 0.1
mmol in methanol 10 ml . Red plates formed immedi-
ately. The red suspension was heated 1 h , cooled
down to room temperature and the red crystals filtered
[ (
)
Ž
3.10. 8- 3-decyloxy-6-hydroxyphenyl -2-phenyl-4,7-di-
azocta-1,3,7-trienato 2- nickel II , 7
]( ) ( ) ( )
.
Ž
.
Ž
.
Ž
Ž
.
Nickel acetate tetrahydrate 99.5 mg; 0.4 mmol was
added to a solution of 6a 0.180 g; 0.4 mmol in
methanol 15 ml heated to reflux. A mass of red
crystals formed immediately. The suspension was heated
to reflux for 1 h. After cooling to room temperature, the
red needles formed were filtered off and recrystallized
.
Ž
.
off and dried in air. Yields28.7 mg 57% . Mps
Ž
.
2098C.
Microanalysis: Calcd for C28 H34O3N2 Ni: C, 66.56;
H, 6.77; N, 5.54. Found: C, 65.10; H, 6.66; N, 5.37.
Calcd for C28 H34O3N2 Ni.CH3OH: C, 64.81; H, 7.13;
N, 5.24.
Ž
.
from methanol. Yields0.163 g 80% .
q
q
Mesomorphism: Cryst 193 SmA 221 Iso 8C.
Microanalysis: Calcd for C28 H36O3N2 Ni: C, 66.30;
H, 7.14; N, 5.51. Found: C, 66.17; H, 7.02; N, 5.39.
Ž
.
Ž
.
Ž
.
MS EI : mrz 504 M y1 ; 365 M yC10 H20 .
y1
Ž
.
.
Ž
IR KBr disc, y cm : 1609 vs, sharp; C5N, C5O
and C5C–N coordinated .
q
q
1
Ž
.
Ž
.
Ž
.
MS EI : mrz 508 M q1 ; 506 M y1 ; 365
Ž
.
Ž
H NMR CDCl3 :7.48-6.80 m, 10H, C6 H4 aro-
q
Ž
.
.
M yC10 H19
.
Ž
matic, HC5N, HCO, NC H5C ; 6.53 m, 1H, aro-
Ž Ž . Ž
y1
Ž
.
.
Ž
IR KBr disc, y cm : 1609 vs, sharp; C5N, C5O
.
Ž
.
matic ; 6.53 m, 1H, Hc ; 5.81 d Jtrans s17 Hz d Jcis
and C5C–N coordinated .
. Ž Ž Ž
.
.
s10 Hz t Jfg s7 Hz , 1H, C H2 sC H ; 4.99 d Jtrans
1
Ž
.
Ž
H NMR CDCl3 : d 7.45-7.10 m, 8H; aromatic
.
.
Ž Ž
.
.
s17 Hz m, 1H, He ; 4.93 d Jcis s10 Hz m, 1H, Hd ;
.
Ž
C6 H5, HC5N, HC5O and NC H5C ; 6.93 m, 2H,
Ž Ž
Ž Ž
.
.
Ž
3.92 t Js7 Hz , 2H, C H2O ; 3.37 m, 2H, CH2–
.
Ž
.
.
Ha, Hb ; 6.52 m, 1H, Hc ; 3.82 t Js7 Hz , 2H,
.
Ž
.
Ž
N5C H ; 3.30 m, 2H, C H2–NH ; 2.04 m, 2H, C H2–
.
Ž
.
Ž
Ž
C H2O ; 3.38 m, 2H, C H2–N5CH ; 3.31 m, 2 H,
.
Ž
.
Ž
CH5 ; 1.70 m, 2H, C H2–CH2–O ; 1.30 m, 10H,
. .
.
Ž
.
C H2–NH ; 1.72 m, 2H, C H2–CH2–O ; 1.30 m, 14H,
. . Ž Ž
Ž
C H2
.
5
Ž
.
.
C H2 ; 0.89 t Js7 Hz , 3H, CH3 .
7
[ (
(
(
3.13. 8- 2-Hydroxy-5- 10- 1,1,3,3,3-pentamethyldi-
[ (
)
3.11. 8- 3-Dec-9-enyloxy-6-hydroxyphenyl -2-phenyl-
4,7-diazocta-1,3,7-trienato 2- nickel II , 8
)
)
)
siloxy decyloxy phenyl -2-phenyl-4,7-diazocta-1,3,7-tri-
]( ) ( ) (
]( ) ( ) ( )
)
enato 2- nickel II , 10
Ž
A suspension of nickel acetate tetrahydrate 0.1941
10 ml of 3–3.5% solution of Karstedt’s catalyst
platinum 0 divinyldisiloxane complex in xylene Flu-
.
Ž
.
Ž
Ž .
.
Ž
g, 0.78 mmol in methanol 5 ml was added to a

(
)
I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
309
Table 3
.
Ž .
orochem was added to a solution of nickel II complex
Ž
.
Positional parameters and B eq for 12
Ž
.
Ž
.
8 0.1731 g, 0.342 mmol in toluene 8 ml under a dry
nitrogen atmosphere. The solution was stirred 1 h at
room temperature and a solution of pentamethylhydro-
Ž .
B eq
Atom
x
y
z
Ž
.
Ž .
0.1371 9
Ž .
Ž .
0.9511 1
Ž .
3.42 6
Ni
0.2058 2
0.01025 6
0.0827 3
Ž .
Ž .
Ž .
Ž .
0.9003 6
Ž .
4.0 4
O 1
Ž
. Ž
.
disiloxane Fluorochem 44.1 mg, 0.297 mmol in
Ž .
Ž .
Ž .
y0.0092 3
Ž .
0.7847 6
Ž .
.1 3
O 2
0.1486 9
Ž
.
toluene 5 ml was added dropwise over a period of 1 h.
IR spectral monitoring of the reaction showed complete
disappearance of the Si–H band in 2–4 h. The red
solution was stirred overnight and the solvent removed
Ž .
Ž .
Ž .
0.1089 5
Ž .
0.654 1
Ž .
13 1
O 3
0.248 2
Ž .
Ž .
Ž .
Ž .
1.1164 8
Ž .
3.7 4
N 1
0.267 1
0.0293 3
y0.0609 4
0.1277 5
0.1276 4
0.1784 5
0.2275 5
0.2281 5
Ž .
Ž .
Ž .
Ž .
Ž .
3.3 4
N 2
0.282 1
0.9920 8
Ž .
Ž .
Ž .
Ž .
Ž .
4.0 2
C 1
0.189 1
1.098 1
Ž .
Ž .
Ž .
Ž .
Ž .
3.6 2
C 2
0.134 1
0.970 1
Ž
.
in vacuo. The residue was dissolved in CH2Cl2 5 ml ,
passed down a short pasteur pipette loaded with Hyflo
Filter Aid and the red solution layered with methanol
Ž .
Ž .
Ž .
Ž .
Ž .
5.0 3
C 3
0.065 1
0.915 1
Ž .
0.985 1
Ž .
Ž .
Ž .
Ž .
5.4 3
C 4
0.064 1
Ž
Ž
.
Ž .
Ž .
Ž .
Ž .
Ž .
6.2 3
C 5
0.125 2
1.107 1
Ž .
1.163 1
.
80 ml to yield red–brown needles which were recrys-
Ž .
Ž .
Ž .
Ž .
5.2 3
C 6
0.190 2
0.1798 5
0.0786 5
Ž .
Ž .
Ž .
Ž .
Ž .
4.6 6
tallized from CH2Cl2rMeOH once more to afford 10 as
C 7
0.258 1
1.161 1
Ž .
Ž .
Ž .
Ž .
Ž .
9 1
C 8
0.344 2
y0.0191 6
1.190 1
Ž
.
red–brown needles. Yields0.14 g 72% .
Ž .
C 10
Ž .
Ž .
Ž .
Ž .
7.0 8
C 9
Ž
0.351 2
y0.0164 6
1.329 1
Ž .
1.128 1
Mesomorphism: Cryst1 164 Cryst2 184 SmA 240 Iso
.
.
.
.
.
.
.
.
.
.
.
Ž .
Ž .
y0.0710 5
Ž .
6.0 8
0.321 2
Ž
.
8C .
Microanalysis: Calcd for C33 H50O4 N2 NiSi2: C,
60.64; H, 7.70; N, 4.28. Found: C, 62.01; H, 7.55; N,
4.39.
Ž
Ž .
Ž .
Ž .
Ž .
4.2 6
C 11
0.308 1
y0.1043 5
0.920 1
Ž .
0.788 1
Ž
Ž .
Ž .
y0.1030 5
Ž .
3.8 6
C 12
0.272 1
Ž
Ž .
Ž .
Ž .
Ž .
4.9 7
C 13
0.192 2
y0.0552 6
0.730 1
Ž .
0.712 1
Ž
Ž .
Ž .
y0.1510 5
Ž .
3.9 6
C 14
0.330 1
Ž
Ž .
Ž .
Ž .
Ž .
4.8 6
C 15
0.320 2
y0.2059 5
0.756 1
Ž .
0.693 1
Ž
Ž .
Ž .
y0.2512 5
Ž .
5.8 7
C 16
0.391 2
Table 2
Ž
Ž .
Ž .
Ž .
Ž .
6.0 8
C 17
0.462 2
y0.2420 7
0.578 1
Ž .
0.534 1
Experimental details for the structure determination of 12
Ž
Ž .
Ž .
y0.1876 7
Ž .
6.4 8
C 18
0.468 2
A. Crystal data
Empirical formula
Crystal color, habit
Crystal dimensions mm
No. reflections used for unit
Ž
Ž .
Ž .
Ž .
Ž .
4.8 6
C 19
0.400 2
y0.1430 5
0.597 1
C20 H22O3N2 Ni
red, prism
0.60=0.33=0.20
Ž
Ž .
Ž .
0.092 1
Ž .
Ž .
15 2
C 20
0.111 3
0.563 1
Ž .
H O
0.2350
0.0181
0.0231
0.1282
0.2299
0.2963
0.4871
0.3584
0.1527
0.2663
0.3832
0.5164
0.5134
0.4091
0.0862
0.1778
0.2614
0.2612
0.1799
0.0839
y0.0154
y0.1371
y0.0571
y0.2129
y0.2887
y0.2727
y0.1837
y0.1067
0.0999
0.1132
0.0529
0.0198
y0.0276
y0.0433
y0.0859
y0.0986
0.7718
0.8300
0.9450
1.1531
1.2502
1.2489
1.1777
0.9578
0.6408
0.8323
0.7258
0.5375
0.4536
0.5592
0.5865
0.4851
0.5424
1.3585
1.3550
1.3651
1.1627
1.1494
13.7
6.2
6.6
7.4
6.2
5.3
11.7
5.2
5.6
5.5
6.5
6.4
7.3
Ž
.
Ž .
H 3
Ž .
H 4
Cell determination
Omega scan peak width at half-height 0.40
25
Ž .
H 5
Ž .
H 6
˚
Ž .
as7.332 3 A
Lattice parameters
Ž .
H 7
Ž .
˚
Ž .
bs23.604 7 A
H 8
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
˚
Ž .
cs10.689 4 A
H 11
Ž
Ž .
H 13
b s94.60 5
Ž
Ž .
H 14
Vs1844 2 3
Ž
H 15
Space Group
P2l rc
Ž
H 16
Z value
4
m MoK a
10.76 cmy1
Ž
Ž
.
H 17
Ž
H 18
5.1
B. Intensity measurements
Diffractometer
Radiation
Ž
H 21
y0.0078
0.1260
0.1205
0.3814
0.2345
0.4406
0.2153
0.4137
16.9
16.9
16.9
7.3
7.3
7.3
Rigaku AFC6S
MoK a ls0.71069
Ž
H 22
Ž
.
Ž
H 23
Temperature
218C
Ž
H 91
Scan type
Scan rate
vy2u
Ž
H 92
Ž
.
88rmin in v
Ž
H 93
2umax
54.18
Ž
.
.
H 101
10.7
5.4
No. of reflections measured
Corrections
Total 4486, unique 4171
Lorentz-polarization,
Ž
H 102
Ž
absorption trans. factors:
.
0.69–1.32 decay
y9.20% decline
q
q
Ž
.
Ž
.
M
Ž
Ž
Ž
.
MS EI : mrz 652 M y1 ; 504 M y CH3 3Si–
Ž
.
q
Ž
. .
Ž
Ž
.
O – S i C H
Si CH 3 2 C 10 H 20
;
3 6 5
y C H 3 S i-O -
3
2
3
q
C. Structure solution and refinement
Structure solution
Refinement
Ž
Ž
.
.
Ž .
y CH 3 3 Si-O-
;
349
M
Ž
.
Heavy atom Patterson
.
.
Si CH3 2C10 H20O .
Full-matrix least-squares
y1
Ž
.
Ž
Ž<
<
<
<.2
.
IR KBr disc; y, cm : 1608 vs, sharp; C5N,
Function minimized
Least-squares weights
p-factor
Ý w Fo y Fc
2
4Fo2rs 2 Fo
. Ž
Ž
C5O and C5C–N coordinated ; 1057 vs, broad; Si–
0.03
1287
205
.
O–Si .
2
2
1
Ž
Ž
.
No. observations F0 )3 s F0
No. variables
Ž
.
Ž
.
Ž
.
.
H NMR CD2Cl2 : d 7.43 s, 1H , 7.28 m. 3H ,
Ž
7.14 m, 4H, aromatic Ph, HC5N,HC5O, N–C H5C ;
Ž Ž . Ž Ž Ž
Residuals: R; Rw
Goodness of fit indicator
0.062; 0.063
1.91
.
.
6.87 d Jab s9 Hz d Jbc s3 Hz , 1H, Hb ; 6.71 d Jab
.
.
Ž Ž
.
.
s9 Hz , 1H, Ha ; 6.54 d Jbc s3 Hz 1H, Hc ; 3.80

(
)
310
I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
Ž Ž
.
.
Ž
.
.
Ž
t Js6 Hz 2H, C H2O ; 3.30 m, 4H, C H2 N ; 1.69
C H2–Si ; 0.10-0.01 several singlets; 6H, CH2 –
Ž
.
Ž
Ž
. .
Ž
Ž
.
.
m, 2H, C H2–CH2O ; 1.30 m, 14H, C H2 ; 0.49 m,
2H, C H2–Si ; 0.04 s, 9H, C H3 3Si–O ; 0.01 s, 6H,
CH2– C H3 Si–O .
C H3 2–Si–O .
7
.
Ž
.
Ž
.
.
Ž
3.15. Structure determination of 12
Ž
.
2
All measurements were made as previously described
{
[ (
(
)
)
}
3.14. Bis 8- 2-hydroxy-5- dec-10-yl-1-yloxy phenyl -
w
x
19 on a red prismatic crystal mounted on a glass fiber.
]( ) ( )
2-phenyl-4,7-diazocta-1,3,7-trienato 2- nickel II -
1,1,3,3-tetramethyldisiloxane, 11
The experimental details are summarized in Table 2.
The metal atom position was determined from a 3-D
Patterson function based on all data. This phased the
data sufficiently to locate the other atoms from differ-
ence Fourier maps. Most of the non-hydrogen atoms
were refined anisotropically. Full-matrix least-squares
(
)
5 ml of 3–3.5% solution of Karstedt’s catalyst in
Ž .
xylene was added to a solution of nickel II complex 8
Ž
.
Ž
.
44 mg; 0.008 mmol , in toluene 8 ml under a dry
nitrogen atmosphere. The solution was stirred 1 h at
room temperature and a solution of tetramethyldihydro-
Ž
.
w
x
refinement was carried out using the TEXRAY 20
program set, giving unweighted and weighted agree-
ment factors of:
Ž
. Ž
.
disiloxane Fluorochem 5.69 mg, 0.004 mmol in
Ž
.
toluene 1 ml was added at once. IR spectral monitor-
ing of the reaction showed complete disappearance of
the Si–H band. The red solution was stirred overnight
and the solvent removed in vacuo. The residue was
5
<
<
5
S Fo y F
c
Rs
s0.062
<
<
S Fo
1
2
Ž
.
<
<
<
<
c
2 s0.063
dissolved in CH2Cl2 5 ml , passed down a short
Sw F y F
Ž
.
o
Rw s
Ž
.
pasteur pipette loaded with Hyflo Filter Aid and the
red solution evaporated under vacuo; the red solid ob-
tained was washed with a little toluene, diethyl ether
SwFo2
The standard deviation of an observation of unit
weight 6 was 1.91.
Ž
.
and dried under vacuum. Yields31 mg 64% .
Mesomorphism: Cryst 176 SmA 220 Iso 8C.
Tables 3 and 4 give the atomic fractional coordinates
and selected interatomic distances and angles, respec-
tively. The molecular structure consists of a neutral
Microanalysis: Calcd for C60 H82O7 N4 Ni2 Si2: C,
62.95; H, 7.21; N, 4.89. Found: C, 62.05; H, 7.09; N,
Ž .
4.80.
Ni II complex with a methanol sovate hydrogen-bonded
q
Ž
.
Ž
.
MS FAB : mrz 1145 M , 827, 535, 505, 365.
to the phenolic oxygen of the unsymmetrical ligand.
The metal environment is approximately planar with
y1
Ž
.
Ž
IR KBr disc; y, cm : 1608 vs, sharp; C5N,
˚
.
Ž
C5O and C5C–N coordinated ; 1096-1037 vs, broad;
each of the donor atoms deviating less than 0.02 A from
.
Si–O–Si .
the least squares plane through the first co-ordination
1
Ž
.
Ž
.
Ž
Ž . Ž . Ž . Ž . Ž .
H NMR CD2Cl2 : d 7.44 s, 1H , 7.33-7.08 m,
sphere. The Sal ligand ring O 1 –C 2 –C 1 –C 7 –N 1
.
7H, aromatic Ph, HC5N, HC5O, N–C H5C ; 6.88
Ž Ž . Ž Ž Ž
is coplanar with this plane, as is the phenolic ring. The
.
.
Ž .
d Jab s9 Hz d Jbc s3 Hz , 1H, Hb ; 6.69 d Jab s9
main deviation comes from the other donor ring O 2 –
.
.
Ž Ž Ž Ž
.
.
Ž
.
Ž
.
Ž
.
Ž .
Hz , 1H, Ha ; 6.55 d Jbc s3 Hz 1H, Hc ; 3.81 t Js
C 13 –C 12 –C 11 –N 2 at 10.28 and the attached
.
.
Ž
.
Ž
6 Hz 2H, C H2O ; 3.32 m, 4H, C H2 N ; 1.69 m, 2H,
phenyl at 41.48 to the plane of the first co-ordination
˚
.
Ž
Ž
. .
Ž
Ž
.
C H2–CH2O ; 1.30 m, 14H, C H2 ; 0.49 m, 2 H,
sphere. The closest intermolecular approach 3.308 A
7
Table 4
Selected interatomic distances and angles for 12
˚
Ž .
Distance A
Atom
Atom
Distance
Ž .Ž .
4.383 3 b
Ž .
1.851 6
Atom
Atom
Ž .
N 1
Ž .
N 2
Ni
Ni
Ni
NiX
3.308 3 a
Ni
Ni
Ni
O 2
Ž .
Ž .
1.852 6
NiY
Ž .Ž .
Ž .
1.844 8
Ž .
O 1
Ž .
1.813 7
Intermolecular distances
Ž . Ž .
Ž .Ž .
3.36 2 b
Ž .
Ž .
O 2
Ž .
N 1
Ž .Ž .
3.22 1 a
3.34 1 b
O 1
Ž .
O 3
Ž
2.88 1 a
O 2
Ž .
O 3
Ž .
.
Ž .Ž .
Ž .Ž .
O 1
C 10
Ž .
Ž .
Angle
Ž .
Symmetry operators: a x, y, z; b yx, yy, 2yz; c 1yx, yy, 2yz
Ž .
Angle 8
Atom
Atom
Atom
Atom
Atom
Atom
Ž .
O 1
Ž .
Ž .
O 1
Ž .
C 2
C 13
Ž .
127.2 5
O 1
Ž .
Ni
Ni
Ni
Ni
Ni
Ni
O 2
Ž .
84.9 2
Ni
Ni
Ni
Ni
Ni
Ni
Ž .
Ž .
Ž
.
Ž .
127.0 6
N 1
N 2
N 1
95.4 3
176.2 3
179.1 3
O 2
Ž .
Ž .
Ž .
Ž .
Ž .
Ž .
125.1 7
O 1
N 1
C 7
Ž .
Ž .
Ž .
Ž .
Ž .
Ž .
Ž .
111.9 6
O 2
N 1
C 8
Ž .
Ž .
Ž .
Ž
.
.
Ž .
114.7 6
O 2
Ž .
N 2
Ž .
92.6 3
Ž .
N 2
C 10
Ž .
Ž
Ž .
130.1 7
N 1
N 2
87.0 3
N 2
C 11

(
)
I.M. Saez et al.rJournal of Organometallic Chemistry 551 1998 299–311
311
w x
3
M. Ibn-Elhaj, A. Skoulios, D. Guillon, J. Newton, P. Hodge, H.
is between the nickel atoms of adjacant molecules. The
pairs of molecules have their nickel atoms separated by
4.383 A from each other to form alternating short and
long Ni–Ni separations along an infinite Ni . . . Ni . . . .
Ni . . . Ni . . . . chain.
Ž
.
Coles, Liq. Cryst. 19 1995 373.
w x
4
M. Ibn-Elhaj, A. Skoulios, D. Guillon, J. Newton, P. Hodge, H.
˚
Ž
.
Coles, Journal de Physique II 3 1993 1807.
w x
5
P. Styring, I.M. Saez, N. Gough, E. Sinn, J.W. Goodby, Patent
Ž
.
application No. 9613068.7 filed 21 June 1996 .
w x
Ž .
6
I.M. Saez, P. Styring, Adv. Mater. 8 1996 1001.
I.M. Saez, P. Styring, Mol. Cryst. Liq. Cryst., 1997 in press.
D. Lloyd, C. Reichardt, M. Struthers, Liebigs Ann. Chem.
w x
Ž
.
7
w x
8
Acknowledgements
Ž
.
1986 1368.
w x
9
O. Kubaschewski, E.L. Evans, Metallurgical Thermochemistry,
Dr. Peter Styring is the first DRA Lecturer in Chem-
4th edn., Pergamon, New York, 1958.
Ž
.
istry. We wish to thank the EPSRC for funding IMS
w
w
x
10 I.M. Saez, P. Styring, A.N. Paterson, E. Sinn, in preparation.
Ž
.
x
11 P. Maldivi, L. Bonnet, A.M. Giroud-Godquin, M. Ibn-Elhaj, D.
in the form of a PDRA Grant reference No: Kr08567 .
Ž
.
Guillon, A. Skoulios, Adv. Mater. 5 1993 909.
We gratefully acknowledge everyone at the University
w
w
x
Ž
.
12 S.M. Kelly, Liq. Cryst. 20 1996 443.
Ž
of Hull Analytical Services Brenda Worthington, Alan
D. Roberts and Carol Kennedy for help in the materi-
x
13 A.B. Blake, J.R. Chipperfield, W. Hussain, R. Paschke, E. Sinn,
.
Ž
.
Inorg. Chem. 34 1995 1125.
als’ characterisation and to the University of Sheffield
w
w
w
x
Ž
.
14 A.K. Rappe, W.A. Goddard III, J. Phys. Chem. 95 1991 3358.
Ž
.
x
15 I.M. Saez, P. Styring, in preparation.
for the provision of FAB mass spectra Simon Thorpe
x
16 W. Bras, G.E. Derbyshire, D. Bogg, J. Cooke, M.J. Elwell, B.U.
Ž
.
and osmometry Sue Bradshaw . We would also like to
express thanks to Dr. B.U. Komanschek at Daresbury
Laboratories for his support and help in the SAXS
studies.
Ž
.
Komanschek, S. Naylor, A.J. Ryan, Science 267 1995 996.
w
w
x
Ž
.
17 W. Bras, J. Bouwstra, NIMPR A326 1993 587.
x
18 W. Folkhard, W. Geercken, E. Knoerzer, E. Mosler, H.
Nemetschek-Gansler, T. Nemetschek, M.H.J. Koch, J. Mol.
Ž
.
Biol. 193 1987 405.
w
w
x
19 J.R. Backhouse, H.M. Lowe, E. Sinn, S. Suzuki, S. Woodward,
Ž
.
J. Chem. Soc., Dalton Trans. 1995 1489.
References
x
20 TEXSAN–TEXRAY Structure Analysis Package, Molecular
Ž
.
Structure 1985 .
w x
Ž
.
1
w x
2
J.L. Serrano Ed. , Metallomesogens, VCH, Weinheim, 1996.
J. Newton, H. Coles, P. Hodge, J. Hannington, J. Mater. Chem.
Ž
.
4 1994 869.