Synthesis and characterisation of rod-like metallomesogens of Mn(I) based on Schiff base ligands

Article abstract of DOI:10.1016/S0022-328X(97)00437-3

Complexation of liquid-crystalline imines to Mn(I) carbonyls led to liquid-crystalline complexes when the ligated imine was sufficiently anisotropic. Thus, all two-ring and some three-ring imine ligands were not mesomorphic when complexed, while some thre

Full text of DOI:10.1016/S0022-328X(97)00437-3

Ž
.
Journal of Organometallic Chemistry 551 1998 271–280
ž /
Synthesis and characterisation of rod-like metallomesogens of Mn I
1
based on Schiff base ligands
2
)
Xiao-Hua Liu, M. Nurul Abser , Duncan W. Bruce
Department of Chemistry, UniÕersity of Exeter, Stocker Road, Exeter EX4 4QD, UK
Received 17 June 1997; received in revised form 2 July 1997
Abstract
Ž .
Complexation of liquid-crystalline imines to Mn I carbonyls led to liquid-crystalline complexes when the ligated imine was
sufficiently anisotropic. Thus, all two-ring and some three-ring imine ligands were not mesomorphic when complexed, while some
three-ring and all four-ring imines led to mesomorphic complexes. As expected, complexation disturbed the anisotropy of the ligands and
led to a lowering of clearing points and a suppression of smectic phase formation. q 1998 Elsevier Science S.A.
Keywords: Synthesis; Metallomesogens; Schiff base ligands
Ž
.
1. Introduction
palladium and platinum followed Fig. 1 and the results
w x
of these studies were reported in 1986 9 . He then
suggested the synthesis of stilbazoles Fig. 3 —sub-
stituted pyridines 10 . These ligands served the work
very well and a variety of effects were demonstrated
with them, such as liquid-crystallinity with metals
11,12 , liquid-crystallinity through hydrogen bonding to
acids 13 and phenols 14 , enhanced linear 15 and
non-linear polarisabilities 16 , Langmuir–Blodgett film
formation 17 and pyroelectric response within the L–B
films 18 . However, perhaps the most interesting and
satisfying results, at least from a pure liquid crystal
perspective, were obtained with their complexes to sil-
ver I —another of Peter’s initial suggestions 19–25 .
The subject of this paper relates to organometallic met-
allomesogens—a term coined by Peter 6 —and is ded-
icated to him with much warmth and affection.
An examination of the literature reveals that of all
the thermotropic liquid crystalline complexes synthe-
sised thus far, the vast majority contain metals in linear
or planar environment and usually with a d8–d10 elec-
Ž .
The synthesis and characterisation of metal com-
plexes with liquid crystalline properties is now a well
established area of materials chemistry and has been the
w
x
w
x
subject of several recent reviews 1–5 , including two
w
x
w
x
co-authored by Maitlis 6,7 . Serious UK effort in this
area started in 1984 in Sheffield and DWB remembers
several early conversations with Peter Maitlis on the
subject. The first molecule which Peter drew was
pentylcyanobiphenyl, shown in Fig. 1. Materials of this
type, discovered by George Gray in the early 1970s at
the University of Hull in the UK, led to the widespread
commercialisation of liquid crystal displays. Being an
organometallic chemist first, foremost and at heart,
Peter suggested coordination in an h6 fashion through
one of the rings. Liquid crystals binding Cr CO
fragments in this way have since been reported by
Ziessel and Deschenaux Fig. 2 8 . In fact, it turned
out that with these compounds, which are simply substi-
tuted benzonitriles, coordination through the nitrile ni-
trogen was to be preferred; liquid crystals based on
w
x
w
x
w x
w
x
w
x
w
x
Ž .
w
x
w x
w
Ž
.3x
Ž
. w x
w
x
tronic configurations 26 . Notable exception are the
five-coordinated complexes of vanadyl and Fe III –Cl
moieties 27 , both bound in a square-pyramidal fashion,
some complexes containing Fe CO unit 28 and the
increasing literature of mesomorphic ferrocene com-
plexes 29 . However, most metal complexes are not
derived from metallocenes or from metals in groups
Ž
.
w
x
)
Corresponding author. Tel.: q44-1392-263489; fax: q44-1392-
Ž
.
w x
3
263434; e-mail: d.bruce@exeter.ac.uk.
1 Dedicated to Peter Maitlis on the occasion of his 65th birthday.
2 Present address: Department of Chemistry, Jahangirnagar Uni-
versity, Savar, Dhaka, Bangladesh.
w
x
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

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272
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
Ž .
Ž .
Fig. 1. Cyanobiphenyls and their complexes with Pd II and Pt II .
Fig. 2. Organochromium mesogens described by Ziessel and Deschenaux.
8–12 and so there are whole areas of the periodic table
for which calamitic liquid crystalline complexes have
not been synthesised.
Fig. 3. Structure of 4X-alkoxy-4-stilbazoles.
This is, however, not a straightforward problem, as it
is necessary to match the need of liquid crystals to have
structural anisotropy with the inevitable disruption which
will be caused to such anisotropy by the introduction of
high coordinate, and therefore bulky, metal complex
fragments. Structurally anisotropic molecules are needed
in order to realise liquid crystalline behaviour and hence,
planar metal centres represent excellent molecular com-
ponents as the global anisotropy is unperturbed by their
inclusion.
We previously communicated out initial findings that
w
Ž
.4 x
highly anisotropic imines could be bound to M CO
Ž
.
fragments MsMn, Re with retention of the liquid
w
x
crystal properties 30 . We now report these findings in
detail and provide further examples of liquid-crystalline
manganese complexes.
2. Establishment of a synthetic model
Although mesomorphic manganese complexes were
realised with highly anisotropic ligands, it is worth first
charting the work which preceded these materials. Thus,
in the 1970s, Stone and co-workers had demonstrated
that reaction in light petroleum of benzylidene aniline
w
Ž
.
5x
Ž
.
MsMn, Re led to evolution of
with MMe CO
methane and CO and the generation of the orthometal-
lated complex in yields of about 40%. This was very
important as most work on orthometallated complexes
had concentrated on group 10 metals. Benzylideneani-
Ž .
Fig. 4. Synthesis of octahedral Mn I complexes of two-ring ligands,
Ž .
Ž .
C8 H17 Br, K 2CO3 rDMF; ii
reagents and conditions:
i
w
x
Ž
. Ž . w . x
Ž
line is a very common fragment 31 in organic liquid
tolueneracetic acid 2 drops ; iii MnMe CO rToluene.
5

(
)
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
273
crystals, and work on it can be traced back to the
w
x
beginning of the century 32 . Clearly then, a suitable
metalrligand combination was available.
Initially, we began by synthesising simple two-ring
Ž
.
imines Fig. 4; 1 by reaction of alkoxybenzaldehydes
with alkylanilines. These were then complexed on reac-
w
Ž
. x
tion with MnMe CO .
5
However, in our hands and with these ligands, we
were unable to form the complexes in light petroleum,
and changing the solvent to THF only led to trace
amounts of product. However, carried out in toluene at
reflux, the reaction was complete in 4 h, allowing
Ž .
isolated yields for complexes 2 of more than 90%.
Several derivatives were made, and their thermal be-
haviour is now described.
3. Mesomorphism
w
x
All of the ligands were known 31 and their meso-
morphism is summarised in Table 1. However, none of
the complexes was liquid-crystalline, and all simply
Ž
.
melted straight into an isotropic i.e., normal liquid
state at the temperatures indicated in Table 1. Clearly,
these ligands were insufficiently anisotropic to tolerate
w
Ž
.
x
the introduction of the Mn CO moiety.
4
4. Manganese complexes containing three aromatic
rings
Ž .
3
Fig. 5. Synthesis of three-ring ligands
and related manganese
Ž .
complexes 4 .
In order to enhance the structural anisotropy, it was
therefore necessary to incorporate additional benzene
Ž .
rings into the ligand. The new ligands 3 were synthe-
was esterified with 4-hydroxybenzaldehyde using
DCCrDMAP to give an alkoxybenzoyloxybenzalde-
hyde, which was then condensed with a 4-substituted
aniline to give the required imine. As before, reaction of
sised as shown in Fig. 5. Thus, an alkoxybenzoic acid
w
Ž
. x
the imine with MnMe CO in toluene at reflux gave
5
Table 1
Ž .
the desired complexes 4 in about 70% isolated yield.
Ž .
Ž .
Transition temperatures for ligands 1 and complexes 2
n
Transition
Tr8C DHrkJ mol-1
DSrJ K-1 mol-1
1
6
Crys-SB 44
37.7
3.6
6.2
119
10
17
SB-SA
SA-I
72
84
5. Mesomorphism
1
1
1
7
Crys-SB 33
24.3
3.8
6.8
57.1
4.2
7.8
58.9
3.9
7.8
79
11
19
171
12
22
174
11
The mesomorphism of the ligands, 3, was charac-
terised using DSC and polarising optical microscopy,
and is summarised in Table 2. The re-entrant behaviour
SB-SA
SA-I
75
87
10 Crys-SB 63
SB-SA
SA-I
78
87
w
x
of 3c has previously been noted by Weissflog 33 .
Ž .
Ž
.
The related Mn I complexes 4a–c are non-meso-
morphic. The melting point for 4a, 4b, and 4c are
1108C, 1248C and 1368C, respectively, and careful ex-
amination of the behaviour on cooling failed to reveal
12 Crys-SB 67
SB-SA
SA-I
Crys-I
Crys-I
76
84
40
36
39
57
22
2
2
2
2
6
7
Ž
.
the presence of monotropic metastable mesophases. It
can be readily seen that the complexes’ clearing points
10 Crys-I
12 Crys-I
Ž
are lower than that of their corresponding ligands ca.

(
)
274
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
.
Table 3
Phase transitions of the mesomorphic three-ring complexes 6–8
2008C or over and the more polar the terminal groups,
the higher its melting point.
Ž
.
Ž
.
Compound
n
m
Transition
T 8C
Clearly then, the functionality attached to the core
had an important influence on melting point, at least,
and so it was decided to see whether other modifica-
tions to the three-ring imines could be made which
would allow the generation of mesomorphic complexes
5a
7
8
Crys–I
123
Ž
.
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
I–N
Crys–I
83
93
73
5b
6a
6b
6c
6d
6e
7a
7b
7c
7d
7e
8a
8b
11
12
13
14
15
17
12
13
14
15
17
8
9
Ž
.
Ž
I–N
Crys–I
123
Ž .
of manganese I . The approach taken was to retain the
Ž
.
Ž
I–N
Crys–I
83
104
basic motif of the three-ring ligands discussed above,
but to introduce one terminal group as an alkanoyloxy
function, rather than a simple alkoxy function. The
synthetic approach is shown in Fig. 5 and complexes
5–7 were synthesised in moderate yield 60–70%
from the ligands via reaction with MnMe CO
toluene at reflux.
Two derivatives 5a–b were originally synthesised,
and now, the metal complexes did show liquid crystal
mesophases, having a monotropic nematic phase. Ther-
mal data for the ligands and their related complexes are
collected in Table 3. Monotropic behaviour means
simply that the mesophase is less thermodynamically
stable than the crystal phase, and so appears only on
9
Ž
.
Ž
67
99
Ž
65
97
Ž
65
95
Ž
63
I–N
Crys–I
9
Ž
.
I–N
Crys–I
9
Ž
.
Ž
Ž
.
in
Ž
.
I–N
Crys–I
w
.5x
9
Ž
.
I–N
Crys–I
10
10
10
10
10
102
Ž
.
Ž
.
Ž
I–N
Crys–I
67
101
Ž
.
Ž
I–N
Crys–I
66
104
Ž
.
Ž
I–N
Crys–I
64
102
Ž
Ž
.
Ž
Ž
I–N
Crys–I
67
96
64
.
supercooling the isotropic melt. Encouraged by this
Ž
.
I–N
Crys–I
result, we decided to see whether variation of the chain
length in these systems could lead to lower-melting
materials which might allow the melting point to fall to
a sufficiently low temperature to allow enantiotropic
mesomorphism to be seen. To this end, a number of
124
Ž
.
Ž
I–N
Crys–I
85
92
63
Ž
.
Ž
I–N
ligands were synthesised based on a nonyloxy or decy-
loxy group at one end and an alkanoyloxy group at the
other. Unfortunately, the ligands were made in rather
small quantities and so the ligand mesomorphism has
not been characterised. However, there is every reason
to assume that it will be similar to that of the two
initially prepared ligands.
Table 2
Ž
.
Phase transitions of the three-ring ligands 3–5
Compound Transition T 8C D HrkJ moly1 DSrJ Ky1 moly1
Ž
.
3a
Crys–K
K–SI
SI –SC
SC –N
N–I
69
74
76
149
193
14.4
0.4
0.9
1.3
1.5
42
1
3
3
3
All of these new complexes were mesomorphic, but
again, only monotropic phases resulted. Indeed, the
Ž
.
melting and monotropic clearing points were remark-
ably independent of chain length as may be seen from
3b
3c
3d
3e
Crys–SA
97
26.1
y
0.7
0.9
71
y
2
Ž
.
Ž .
SA –E
89
SA –N
N–I
181
204
2
Crys–Nrae 108
y
y
y
y
y
y
y
y
Nre –SA
SA –N
N–I
152
198
255
Crys–G
G–SC
SC –N
N–I
72
94
148
212
23.2
2.7
1.5
1.2
67
7
4
3
Crys–G
G–SC
SC –N
N–I
76
100
172
201
33.3
2.5
2.8
1.8
96
7
6
4
aRe-entrant nematic phase.
Fig. 6. Phase diagram for complexes 6 and 7.

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X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
275
of the complexes to the arrangement of ligand function-
alities bound to it.
Thus, while we had generated manganese complexes
which were now mesomorphic, which did not decom-
pose and which had relatively low clearing points, the
higher melting points led to the observation of only
monotropic phases. We therefore decided to press the
idea of ligand anisotropy one step further, and under-
took the synthesis of some four-ring imine ligands and
Fig. 7. Isomeric three-ring manganese complexes.
Ž .
their complexes with Mn I .
Fig. 6. DSC data were not recorded as it was not always
possible to see the monotropic N–I transitions in the
DSC experiment, even though they were always ob-
served by optical microscopy.
( )
6. Manganese I complexes containing four rings
Ž
Finally here, we synthesised two complexes Fig. 7;
.
Ž .
Ž
.
8a and 8b in which the ends of the ligand had been
The ligands 9 and complexes 10 were synthesised
as shown in Fig. 8.
effectively ‘swopped over’; the synthetic approach was
exactly analogous to that described for the structurally
isomeric ligands. The thermal data are collected in
Table 3 alongside their isomers, and the correspondence
in transition temperatures is remarkable and is, within
experimental error, identical, showing the insensitivity
The new ligands were synthesised using the same
synthetic steps employed in the smaller ligands, the
only extra step being the formation of alkoxybenzoy-
loxynitrobenzene by a DCCrDMAP coupling of an
alkoxybenzoic acid with 4-nitrophenol, followed by its
Fig. 8. Synthesis of four-ring ligands and complexes.

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X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
Table 4
8. Conclusion
Ž .
Ž .
Mesomorphism of the ligands 9 and complexes 10 containing four
ringsi
By way of conclusion, some useful comparisons
between the behaviour of the ligands and their man-
ganese complexes can be made. First, it is noteworthy
that the temperature at which the complexes pass into
the nematic phase is not much different from the tem-
perature at which the ligands pass into a fluid
mesophase. The mesomorphism, however, is quite dif-
ferent in that the fluid and ordered smectic phases seen
in the ligands have been destabilised so that only ne-
matic phases are seen in the complexes. In many ways,
this is expected as the introduction of a bulky lateral
substituent would be predicted to reduce that occurrence
of smectic phases which require lateral associations.
Despite this, we have found that in mesomorphic com-
plexes of 2,2X-bipyridines 34 and of 1,4-di-
w
x
w
x
w
Ž
.3x
azabutadienes 35 bound the to the ReBr CO frag-
ment, smectic C mesophases are seen at certain chain
lengths. The origin of this difference in behaviour is, for
the present, unclear. The other consequence of the
w
Ž
.
x
introduction of the lateral Mn CO group is to reduce
4
the overall anisotropy and therefore, it is again unsur-
prising that the clearing point of the complexes is much
lower than that of the ligands, in fact by some 1008C,
even though the thermal stability was such that the
complexes decomposed in the upper reaches of the
nematic phase, accelerating on clearing.
Evidently, these are systems of great promise, partic-
ularly with respect to the formation of stable, low-melt-
ing metallomesogens—one of Peter’s great aspirations
for the field.
Ž .
reduction to alkoxybenzoyloxyaniline using tin II . The
manganese complexes were then prepared in 65% yield
by reaction of the ligands with MnMe CO in toluene
w
Ž
.
x
5
at reflux for 8 h.
9. Experimental
7. Mesomorphism
Apparatus and general techniques of microscopy and
The ligands showed extensive mesomorphism, with
all having SC and nematic phases. Two then showed
subsequent formation of a crystal G phase on further
cooling of the SC phase, while for the heptylcyclohexyl
derivative, a crystal J and a SI phase were introduced
beneath the SC phase, as characterised by optical mi-
croscopy. As expected with such highly anisotropic
ligands, the clearing points were rather high at around
3008C. The thermal data are collected in Table 4.
As now expected, the related complexes were meso-
morphic. Thus, 10a, 10b, and 10c melted in a nematic
phase at 135, 122 and 1548C, clearing, with decomposi-
tion, at 184, 180 and 1908C respectively. Thus, by using
the strongly anisotropic, four-ring imines, the perturba-
w
x
calorimetry are as described elsewhere 35 .
X
(
)
9.1. 4 - 4-Octyloxybenzoyloxy benzaldehyde
Ž
.
Dicyclohexylcarbodiimide 5.94 g, 28.8 mmol and
Ž
.
N,N-dimethylaminopyridine 0.15 g were added to a
stirred solution of 4-octyloxybenzoic acid 6.0 g, 24
mmol and hydroxybenzaldehyde 3.0 g, 24.0 mmol in
dry dichloromethane DCM, 100 cm . The reaction
mixture was stirred at room temperature for 6 h. The
dicyclohexylurea was filtered off and the solvent from
the filtrate was removed under reduced pressure. The
crude product was purified by column chromatography
Ž
.
Ž
.
3
Ž
.
w
Ž
.
x
tion represented by the Mn CO group was tolerated
4
Ž
.
Ž
and liquid crystal behaviour resulted.
silica gel, DCM . A colourless product was obtained.
Yield, 7.35 g 87% . m.p. 1038C. H NMR CDCl3
d: 0.9 t, 3H, CH3 , 1.34–1.85 m, 12H, 6CH2 , 4.05
1
.
Ž
.
a With decomposition.
Ž
.
Ž
.

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)
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
277
1
Ž
.
Ž
Ž
.
Ž
.
t, 2H, Js6.5 Hz, OCH2 , 6.98 d, 2H, Js9.0 Hz,
Yield, 3.24 g 70.4% . m.p. 948C. H NMR CDCl3
X
X
X
X
.
Ž
.
Ž
Ž
.
Ž
.
AA XX , 7.4 d, 2H, Js9.0 Hz, AA XX , 7.95 d,
d: 0.9 t, 3H, CH3 , 1.17;1.55 m, 10H, 5CH2 , 1.82
qn, 2H, OCH2CH2 , 3.64 s, 2H, NH2 , 4.03 t, 2H,
X
X
.
Ž
Ž
.
Ž
.
Ž
2H, Js9.0 Hz, AA XX , 8.12 d, 2H, Js9.0 Hz,
X
X
X
X
.
Ž
.
.
Ž
.
AA XX , 10.02 s, 1H, CHO ppm.
Js6.5 Hz, OCH2 , 6.7 d, 2H, Js9 Hz. AA XX ,
X
X
Ž
.
Ž
.
Ž
For the next two aldehydes ns5,7 , the synthesis
was performed in an analogous manner—one set of
NMR data is given—the other is similar.
6.95 d, 4H, Js9Hz, 2AA XX , overlapped , 8.1 d,
X
X
.
Ž .
2H, Js9 Hz, AA XX ppm; Elemental analysis % :
Found: C, 73.6; H, 7.8; N, 4.1; C21H27 NO3 requires C,
73.9; H, 8.0; N, 4.1.
X
(
)
9.5. Ligands 1: 4 -octyloxybenzylidene -4-hexylaniline
Ž
.
4-Hexylaniline 3.79 g, 19.2 mmol was dissolved in
3
Ž
.
Ž
.
toluene 25 cm and then acetic acid 2 drops was
added into the solution. 4-Octyloxybenzaldehyde 4.5 g,
19.2 mmol was added to the solution, and stirred for a
Ž
.
1
Ž
.
H NMR 250 MHz, CDCl3, ppm
few minutes then left unstirred overnight. The crude
product was filtered and recrystallized in ethanol to give
9.2. ns5
a colourless crystalline solid.
1
Ž
.
Ž
.
Ž
Yield, 6.45g 85.4% ; H NMR CDCl3 d: 0.9 m,
Ž
.
Ž
.
d: 0.9 t, 3H, CH3 , 1.0 m, 2H, H3ax yH5ax , 1.25
.
Ž
.
Ž
6H, 2CH3 , 1.2–1.6 m, 18H, 9CH2 , 1.8 qn, 2H,
Ž
Ž
Ž
Ž
.
Ž
.
m, 9H, 4CH2 qH4 , 1.55 qd, 2H, H2ax qH6ax , 1.85
.
Ž
.
Ž
OCH2CH2 , 2.6 t, 2H, ph-CH2 , 4.0 t, 2H, Js6.5
.
Ž
.
dd, 2H, H3eq qH5eq , 2.1 dd, 2H, H2eq qH6eq , 2.45
X
X
.
Ž
.
Ž
Hz, OCH2 , 6.95 d, 2H, Js9.0 Hz, AA XX , 7.1 dd,
X
X
.
Ž
.
tt, 1H, H1 , 7.23 d, 2H, Js9.0 Hz, AA XX , 7.94
X
X
.
Ž
2H, Js9.0 Hz, AA XX , 7.85 d, 2H, Js9.0 Hz,
X
X
.
Ž
.
d, 2H, Js9.0 Hz, AA XX , 10.0 s, 1H, CHO
X
X
.
Ž
.
AA XX , 8.4 s, 1H, CHsN ppm. Elemental analysis
X
Ž
.
% : Found: C, 81.9; H, 10.0; N, 3.4; C27 H39 NO
requires C, 82.4; H, 9.9; N, 3.6.
(
)
9.3. 4 - 4-Octyloxybenzoyloxy nitrobenzene
Ž
Ž
.
Ž
.
For the homologous Schiff base ligands ns
DCC 34.61 g, 168 mmol and DMAP 0.3 g were
added to a stirred solution of 4-octyloxybenzoic acid
.
7,10,12 , the synthesis was performed in an analogous
Ž
.
Ž
manner; the alkylanilines were commercially available.
NMR data were effectively identical and satisfactory
analytical data were obtained.
35 g, 140 mmol and hydroxybenzaldehyde 29 g, 210
3
.
Ž
.
mmol in dry DCM 400 cm . The reaction mixture
was stirred at room temperature for 6 h. The dicyclo-
hexylurea was filtered off and the solvent was removed
under reduced pressure. The crude product was crystal-
lized from ethanol to give a colourless solid.
1
Ž
.
Ž
.
Ž
Yield, 46.2 g 89% . H NMR CDCl3 d: 0.9 t, 3H,
.
Ž
.
Ž
CH3 , 1.25–1.45 m, 10H, 5CH2 , 1.8 qn, 2H,
.
Ž
.
Ž
OCH2CH2 , 4.05 t, 2H, Js6.5 Hz, OCH2 , 6.98 d,
For the ligands 3, the synthesis was performed in an
analogous manner starting from the corresponding
alkoxybenzoyloxybenzaldehyde; the aniline derivatives
were commercially available.
X
X
X
X
.
Ž
.
2H, Js9 Hz, AA XX , 7.4 d, 2H, Js9Hz, AA XX ,
X
X
Ž
.
Ž
8.1 d, 2H, Js9.0 Hz, AA XX , 8.13 d, 2H, Js9
X
X
.
Ž .
Hz, AA XX ppm; Elemental analysis % : Found: C,
68.0; H, 6.8; N, 3.9; C21H25NO5 requires C, 67.9; H,
6.8; N, 3.8.
X
(
)
9.4. 4 - 4-Octyloxybenzoyloxy aniline
X
Ž
.
A mixture of 4 - 4-octyloxybenzoyloxy nitrobenzene
9.5.1. RsC6 H13 3a
Ž
. Ž
.
Ž
(
)
25 5 g, 13 mmol and 5 equiv. of SnCl2 P2H2O 15.2
1
3
.
Ž
.
Ž
.
Ž
.
.
Ž
g, 65 mmol was refluxed in ethanol 100 cm for 6 h.
After cooling, the mixture was poured into ice and the
pH value was adjusted to 7;8 using sodium hydrox-
ide. The mixture was extracted with ethyl acetate. The
ethyl acetate solution was washed three times with brine
and was dried over anhydrous MgSO4. The solvent was
evaporated under reduced pressure. The brownish solid
Yield, 67% ; H NMR CDCl3 d: 0.9 m, 6H,
.
Ž
Ž
2CH3 , 1.2–1.6 m, 18H, 9CH2 , 1.85 qn, 2H,
.
.
Ž
.
Ž
OCH2CH2 , 2.6 t, 2H, ph-CH2 , 4.05 t, 2H, Js6.5
X
X
Ž
.
Ž
Hz, OCH2 , 6.98 d, 2H, Js9.0 Hz, AA XX , 7.12 d,
X
X
.
Ž
2H, Js9.0 Hz, AA XX , 7.18 d, 2H, Js9.0 Hz,
X
X
X
X
.
Ž
.
Ž
AA XX , 7.3 d, 2H, Js9.0 Hz, AA XX , 7.95 d,
X
X
.
Ž
2H, Js9.0 Hz, AA XX , 8.15 d, 2H, Js9.0 Hz,
X
X
Ž
.
Ž
.
was purified by column chromatography silica gel:
DCM and 1% triethylamine and then crystallized from
AA XX , 8.45 s, 1H, CHsN ppm. Elemental analy-
.
Ž
.
sis % : Found: C, 79.4; H, 8.6; N, 2.6; C34 H43NO3
requires C, 79.5; H, 8.4; N, 2.7.
ethanol to give a whitish solid.

(
)
278
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
(
)
.
Ž
9.5.2. RsF 3b
2CH3 qH3ax yH5ax , 1.2–1.65 m, 25H, 9CH2 qH4
1
Ž
.
Ž
.
Ž
Ž
.
.
.
Ž
Yield, 70% ; H NMR CDCl3 d: 0.9 t, 3H, CH3 ,
1.28–1.55 m, 10H, 5CH2 , 1.8 qn, 2H, OCH2CH2 ,
q H 2ax q H6ax
,
1.85 m, 4H, H3eq q H5eq
q
Ž
.
.
Ž
Ž
.
Ž
OCH2CH2 , 2.15 dd, 2H, H2eq qH6eq , 2.5 tt, 1H,
Ž
.
Ž
.
.
Ž
4.05 t, 2H, Js6.5 Hz, OCH2 , 6.95 d, 2H, Js9.0
H1 , 4.05 t, 2H, Js6.5 Hz, OCH2 , 6.95 d, 2H,
X
X
X
X
X
X
.
Ž
.
Ž
.
Ž
Hz, AA XX , 7.05 dd, 2H, AA XX , 7.2 m, 2H,
Js9.0 Hz, AA XX , 6.95 d, 2H, Js9.0 Hz,
X
X
X
X
X
X
X
X
.
Ž
.
Ž
.
Ž
.
Ž
AA XX , 7.3 d, 2H, Js9.0 Hz, AA XX , 7.94 d,
AA XX , 7.2 m, 6H, AA XX , overlapped , 7.9 d, 2H,
X
X
X
X
.
Ž
.
Ž
2H, Js9.0 Hz, AA XX , 8.17 d, 2H, Js9.0 Hz,
Js9.0 Hz, AA XX , 8.15 d, 2H, Js9.0 Hz,
X
X
X
X
.
Ž
.
.
Ž
.
AA XX , 8.45 s, 1H, CHsN ppm. Elemental analy-
AA XX , 8.45 s, 1H, CHsN ppm. Elemental analy-
Ž
.
Ž
.
sis % : Found: C, 74.9 H, 6.9; N, 3.0; C28 H30 NFO3
requires C, 75.1; H, 6.8; N, 3.1.
sis % : Found: C, 76.9; H, 8.5; N, 2.1; C42 H55NO5
required C, 77.1; H, 8.5; N, 2.1.
(
)
9.5.3. RsCN 3c
1
Ž
.
Ž
.
Ž
.
Yield, 78% ; H NMR CDCl3 d: 0.9 t, 3H, CH3 ,
Ž
.
Ž
.
1.17–1.55 m, 10H, 5CH2 , 1.8 qn, 2H, OCH2CH2 ,
Ž
.
Ž
4.0 t, 2H, Js6.5 Hz, OCH2 , 6.95 d, 2H, Js9.0
X
X
X
X
.
Ž
.
Hz, AA XX , 7.15 d, 2H, Js9.0 Hz, AA XX , 7.3
X
X
X
X
Ž
.
Ž
.
d, 2H, AA XX , 7.6 d, 2H, Js9.0 Hz, AA XX ,
X
X
1
Ž
.
Ž
7.92 d, 2H, Js9.0 Hz, AA XX , 8.1 d, 2H, Js9.0
Ž
.
Ž
.
Yield 86.3%; H NMR CDCl3 d: 0.9 t, 6H, 2CH3 ,
X
X
.
.
Ž
.
Hz, AA XX , 8.35 s, 1H, CHsN ppm. Elemental
Ž
.
Ž
.
1.25–1.5 m, 22H, 11CH2 , 1.85 m, 4H, OCH2CH2 ,
Ž
analysis % : Found: C, 76.3 H, 6.6; N, 6.3;
C29 H30 N2O3 requires C, 76.6; H, 6.7; N, 6.2.
Ž
.
Ž
4.05 t, 4H, Js9.0 Hz, 2OCH2 , 6.95 d, 4H, Js9.0
X
X
X
X
.
Ž
.
Ž
Hz, AA XX , 7.2–7.35 m, 6H, AA XX , 7.9 d, 2H,
X
X
Ž .
Four-ring imine ligands 9 were synthesized simi-
.
Ž
Js9.0 Hz, AA XX , 8.15 d, 4H, Js9.0 Hz,
X
X
13
Ä1
4
Ž
larly to the two-ring imines, 1, except the final products
were purified by crystallization from DCMrmethanol.
.
Ž
.
AA XX , 8.45 s, 1H, CHsN ppm. C H NMR 250
.
MHz CDCl3 : d: 14.11, 22.66, 25.99, 29.11, 29.23,
29.33, 31.8, 68.36, 114.3, 114.4, 121.2, 121.5, 121.8,
122.2, 122.4, 130.0, 132.3, 132.4, 133.7, 149.3, 149.4,
153.6, 159.3, 163.6, 163.7, 164.6, 165.0 ppm; Elemen-
Ž
.
tal analysis % : Found: C, 75.9; H, 7.7; N, 2.0;
C43 H51NO6 required C, 76.2; H, 7.6; N, 2.1.
Three ring Schiff base ligands which have alkanoy-
loxy terminal groups were synthesised as described
below. Analytical and NMR data are given for one
example, all the others gave similar, satisfactory results.
1
Ž
.
Ž
Yield 81.4%; H NMR CDCl3 d: 0.85–1.1 m 8H,
.
Ž
2CH3 qH3ax yH5ax , 1.2–1.65 m, 21H, 9CH2qH4
.
Ž
1.85 m, 4H, H3eq q H5eq q
q H 2ax q H6ax
,
.
Ž
.
Ž
Ž
OCH2CH2 , 2.15 dd, 2H, H2eq qH6eq , 2.5 tt, 1H,
.
Ž
.
H1 , 4.05 t, 2H, Js6.5 Hz, OCH2 , 6.95 d, 2H,
X
X
.
Ž
Js9.0 Hz, AA XX , 6.95 d, 2H, Js9.0 Hz,
X
X
X
X
.
Ž
.
Ž
AA XX , 7.2 m, 6H, AA XX overlapped , 7.9 d, 2H,
X
X
.
Ž
Js9.0 Hz, AA XX , 8.15 d, 2H, Js9.0 Hz,
X
X
.
Ž
.
AA XX , 8.45 s, 1H, CHsN ppm. Elemental analy-
Ž
.
sis % : Found: C, 77.0 H, 8.5; N, 2.3; C40 H51NO5
required C, 76.8; H, 8.2; N, 2.2.
(
)
9.5.4. ms7 5a
Ž
.
Ž
.
DCC 0.33 g, 1.6 mmol and DMAP 0.05 g were
added to a stirred solution of octanoic acid 0.2 g, 1.3
mmol and compound 33 0.6 g, 1.3 mmol in dry DCM
30 cm . The reaction mixture was stirred at room
Ž
.
Ž
.
3
Ž
.
temperature for 12 h. The dicyclohexylurea was filtered
and the solvent was removed under reduced pressure.
The crude product was crystallized from
DCMrmethanol to give a colourless solid.
1
Ž
.
Ž
Yield 0.54 g, 69%; H NMR CDCl3 d: 0.9 6H,
.
Ž
2CH3, two overlapped triplets , 1.25–1.5 m, 18H,
1
Ž
.
Ž
. Ž .
9CH2 , 1.8 m, 4H, CH2CH2CO2 qOCH2CH2 , 2.55
Yield 90%. H NMR CDCl3 d: 0.85–1.1 m, 8H,

(
)
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
279
Ž
Ž
.
Ž
.
t, 2H, CH2CO2 , 4.05 t, 2H, Js6.5 Hz, OCH2 , 6.95
Commission for the award of a Marie-Curie training
X
X
.
Ž
Ž
d, 2H, Js9.0 Hz, AA XX , 7.1 d, 2H, Js9.0 Hz,
fellowship under the ALA programme Contract No.
X
X
X
X
)
.
Ž
.
Ž
.
AA XX , 7.2 d, 2H, Js9.0 Hz, AA XX , 7.33 d,
CI1 -CT93-0114 .
X
X
.
Ž
2H, Js9.0 Hz, AA XX , 7.95 d, 2H, Js9.0 Hz,
X
X
X
X
.
Ž
.
Ž
AA XX , 8.15 d, 2H, Js9.0 Hz, AA XX , 8.45 s,
.
Ž .
1H, CHsN ppm. Elemental analysis % : Found: C,
75.4; H, 7.7; N, 2.4; C36 H45NO5 required C, 75.7; H,
7.9; N, 2.5.
References
w x
1
Ž
.
D.W. Bruce, in: D.W. Bruce, D. O’Hare Eds. , Inorganic
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9.6. Mn complexes
w x
Ž .
2
w x
3
J.L. Serrano Ed. , Metallomesogens. VCH, Weinheim, 1996.
Ž .
All Mn I complexes were synthesized in an analo-
Ž
.
D.W. Bruce, J. Chem. Soc., Dalton Trans., 1993 2983.
P. Espinet, J.L. Serrano, L.A. Oro, M.A. Esteruelas, Coord.
w x
4
gous manner by using the method now described. When
the number of rings in the ligands were increased from
two to four, the reaction time was increased from 4 to 8
h.
Under a nitrogen atmosphere, an equimolar amount
of the Schiff base and MnMe CO were dissolved in
dry toluene and heated at reflux for between 4 and 8 h.
depending on the ligand. The solvent was removed in
vacuo and passed through a column of neutral alumina
eluting with DCM. The yellow band from the column
gave, on removal of the solvent, a yellow solid which
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uct.
Ž
.
Chem. Rev. 117 1992 215.
w x
5
Ž
.
A.P. Polishchuk, T.V. Timofeeva, Russ. Chem. Rev. 62 1993
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6
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Ž
.
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Ž
.
x
w x
Ž
.
7
S.A. Hudson, P.M. Maitlis, Chem. Rev. 93 1993 861.
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5
w x
8
Ž
.
w x
9
Ž
.
J. Chem. Soc., Chem. Commun., 1986 581.
w
w
w
x
10 D.W. Bruce, D.A. Dunmur, E. Lalinde, P.M. Maitlis, P. Styring,
Ž
.
Liq. Cryst. 3 1988 385.
x
11 J.P. Rourke, F.P. Fanizzi, N.J.S. Salt, D.W. Bruce, D.A. Dun-
mur, P.M. Maitlis, J. Soc., Chem. Commun., 1990, 229.
x
12 D.W. Bruce, D.A. Dunmur, M.A. Esteruelas, S.E. Hunt, R. Le
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Ž
.
J. Mater. Chem. 1 1991 251.
w
w
w
w
w
x
13 K. Willis, J.E. Luckhurst, D.J. Price, J.M.J. Frechet, T. Kato, G.
Ungar, D.W. Bruce, Liq. Cryst. 21 1996 585.
14 D.J. Price, K. Willis, T. Richardson, G. Ungar, D.W. Bruce,
´
Ž
.
x
Ž
.
J. Mater. Chem. 7 1997 883.
x
15 C. Bertram, D.W. Bruce, D.A. Dunmur, S.E. Hunt, P.M. Maitlis,
M. McCann, J. Chem. Soc., Chem. Commun., 1991, 69.
16 D.W. Bruce, A. Thornton, Mol. Cryst., Liq. Cryst. 231 1993
253.
x
Ž
.
Details are given for ns6. All other complexes
gave satisfactory elemental analyses, and related NMR
and infrared data.
x
17 T. Richardson, A. Topac¸li, W.H. Abd Majid, M.B. Greenwood,
D.W. Bruce, A. Thornton, J.R. Marsden, Adv. Mater. Opt.
Ž
.
Electron. 4 1994 243.
w
w
w
x
18 A. Topac¸li, T. Richardson, W.H. Abd Majid, A. Thornton,
Ž
.
D.W. Bruce, J.R. Marsden, Int. J. Elec. 77 1994 951.
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x
19 D.W. Bruce, D.A. Dunmur, E. Lalinde, P.M. Maitlis, P. Styring,
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20 D.W. Bruce, D.A. Dunmur, P.M. Maitlis, P. Styring, M.A.
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R.M. Richardson, J.L. Feijoo, G. Ungar, Mol. Cryst., Liq. Cryst.
Ž
.
Yield 91.2%; m.p. 38–408C; IR DCM solution
2073 w , 1986 vs , 1938 s . 1 H
Ž .
Ž
.
Ž
.
nco cmy 1
:
Ž
.
Ž
.
x
Ž
.
Ž
NMR CD2Cl2 d: 0.9 6H, 2CH3, two overlapped
.
Ž
.
Ž
triplets , 1.2–1.6 m, 18H, 9CH2 , 1.8 qn, 2H,
Ž
.
.
Ž
.
Ž
w
x
OCH2CH2 , 2.6 t, 2H, Ph-CH2 , 4.05 t, 2H, Js6.5
.
Ž
.
Ž
Hz, OCH2 , 6.63 dd, 1H, Js8.4, 2.4 Hz , 7.12 d,
X
X
.
Ž
2H, Js8.4 Hz, AA XX , 7.23 d, 2H, Js8.4 Hz,
Ž
.
206 1991 79.
X
X
.
Ž
.
Ž
AA XX , 7.52 d, 1H, Js2.4 Hz , 7.62 d, 1H, Js8.4
w
w
w
w
x
22 D.W. Bruce, S.C. Davis, D.A. Dunmur, S.A. Hudson, P.M.
Maitlis, P. Styring, Mol. Cryst., Liq. Cryst. 215 1992 1.
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25 D.W. Bruce, B. Donnio, S.A. Hudson, A.-M. Levelut, S.
.
Ž
.
Hz , 8.17 s, 1H, CHsN ppm. Elemental analysis
Ž
.
Ž
.
x
% : Found: C, 66.4; H, 6.4; N, 2.4; C31H38 NO5Mn
Ž
.
requires C, 66.5; H, 6.8; N, 2.5.
x
Ž
.
x
Ž
.
Megtert, D. Petermann, M. Veber, J. Phys. II France 5 1995
Acknowledgements
289.
w
w
x
Ž
.
26 D.W. Bruce, Adv. Mater. 6 1994 699.
x
XHL would like to thank the University of Sheffield
for a scholarship, while MNA thanks the European
27 Yu.G. Galyametdinov, G.I. Ivanova, I.V. Ovchinnikov, Izv.
Akad. Nauk. SSSR Ser. Khim., 1989, 1931.

(
)
280
X.-H. Liu et al.rJournal of Organometallic Chemistry 551 1998 271–280
w
w
x
w
x
32 D.W. Bruce, V. Vill, Liq. Cryst., 1997, in press.
28 L. Ziminski, J. Malthete, J. Chem. Soc., Chem. Commun., 1990,
ˆ
w
x
33 W. Weissiflog, G. Pelzl, D. Demus, Mol. Cryst., Liq. Cryst. 76
1495.
x
Ž
.
Ž
.
29 R. Deschenaux, J.W. Goodby, in: A. Togni, T. Hayashi Eds.
1981 261.
w
w
x
Ferrocenes, Vol. Chap. 9, VCH Verlagsgesellschaft, Weinheim,
1994, p. 471.
34 K.E. Rowe, D.W. Bruce, J. Chem. Soc., Dalton Trans., 1996,
3913.
w
w
x
x
Ž
.
30 D.W. Bruce, X.-H. Liu, J. Chem. Soc., Chem. Commun., 1994,
729.
31 V. Vill, LiqCryst Database 2.1, LCI Publishing, Hamburg.
35 S. Morrone, D. Guillon, D.W. Bruce, Inorg. Chem. 35 1996
7041.
x