Synthesis and mesomorphic properties of γ-substituted β-diketones and their dicarbonylrhodium(I) complexes

Article abstract of DOI:10.1016/S0022-328X(03)00146-3

Five series of 3-(C₁₀H₂₁O-Ph-X-Ph-Y-) substituted pentane-2,4-diones and their dicarbonylrhodium(I) complexes, namely, series 1: X = -CH = CHCOO- and Y = -COO-, series 2: X = -CH - CHCOO-; and Y = -CH=CHCOO-, series 3: X = -COO- and

Full text of DOI:10.1016/S0022-328X(03)00146-3

Journal of Organometallic Chemistry 672 (2003) 86Á93
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www.elsevier.com/locate/jorganchem
Synthesis and mesomorphic properties of g-substituted b-diketones
and their dicarbonylrhodium(I) complexes
Jie Han *, Liang Fu Zhang, Wen Wan
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, PR China
Received 14 January 2003; received in revised form 6 March 2003; accepted 6 March 2003
Abstract
Five series of 3-(C10H21OÃ
series 1: Xꢀ CHÄCHCOOÃ
and Yꢀ CHÄCHCOOÃ, series 4: Xꢀ
synthesized, their mesogenic properties have been investigated using a Nikon polarizing microscope and DSC. It is found the b-
diketones 1aÁ3a, 5a and the complexes 1bÁ3b exhibit liquid crystal behaviors. The effect of the bridging groups of X and Y on the
/
PhÃ
/
XÃ
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PhÃ
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YÃ
COOÃ
CH2OÃ
/
) substituted pentane-2,4-diones and their dicarbonylrhodium(I) complexes, namely,
, series 2: Xꢀ CHÄCHCOOÃ and Yꢀ CHÄCHCOOÃ, series 3: Xꢀ COOÃ
and Yꢀ COOÃ, series 5: Xꢀ NÄNÃ and Yꢀ COOÃ, have been
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Ã
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and Yꢀ
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mesogenic properties of the ligands and the complexes has been explored.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Liquid crystal; b-Diketone; Organometallic complexes
1. Introduction
endeavoring to understand the relationship between the
molecular structures and the mesogenic properties,
herein, we report the synthesis of five series of new b-
diketones and their corresponding complexes based on
dicarbonylrhodium(I) as the terminal group (Chart 1),
the relationship between the molecular structure and the
mesogenic properties has also been explored.
In recent years, there has been a continuing interest in
the synthesis of various b-diketones because they can be
widely used as organic ligands in mesogenic coordina-
tion complexes of most transition metal ions [1Á6].
/
Although a large number of b-diketones have been
reported to date, only a few examples of mesogenic 3-
substituted pentane-2,4-dione have been published [7,8].
To the best of our knowledge, the relationship between
the molecular structure of the b-diketones and its
mesogenic properties has not been explored in detail
yet. So far, the metal ion of b-diketone complexes is
most situated at the center of the molecules, such
molecules have always central symmetry, which will be
disadvantageous to further enhancement of electro-optic
response. Our results [9,10]and recent reports
[11,12]show that the b-diketone complexes with terminal
metal ion have not only good conjugation structure, but
also have great dipole moments, both factors are
beneficial to improve the mesogenic properties. We are
2. Results and discussion
2.1. Synthesis and characterization
Compound 2,4-dioxo-3-pentyl 4-hydroxybenzoate 7
is a key intermediate in the synthesis of g-substituted b-
diketone. The synthesis of 7 had been reported by
Serrano and co-workers which is outlined in Scheme 1
[8].
The three-step synthesis of 7 by Serrano was under-
taken using BrCH2Ph as the protecting reagent and the
expensive Pd/C catalyst as the deprotecting reagent, and
the phase transfer catalyst are used in the reaction.
Generally speaking, the procedure above is complicated
and the total yield is about 40%.
* Corresponding author. Tel.:
85223978.
E-mail address: hhanjie@hotmail.com (J. Han).
ꢁ
/
86-28-85229122; fax:
ꢁ/86-28-
A practical and facile method for the synthesis of 7
has been found, which is outlined in Scheme 2. The
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00146-3

J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á
/93
87
Chart 1.
methyl 4-hydroxybenzoate with the compound 13 [17] to
give the compound 14 smoothly. The b-diketone 4a was
obtained by the reaction of 3-chloropentane-2,4-dione
with the compound 14 according to the similar proce-
dure reported before [18].
The b-diketone 5a was synthesized in a typical
method, which is outlined in Scheme 6.
The structures of the compounds were confirmed by
the elemental analyses, MS, 1H-NMR, infrared (IR) and
Scheme 1. The synthesis of 7 by Serrano and co-workers.
UVÁvis spectroscopies.
/
The IR spectra of the ligands show a strong stretching
vibration frequency at ca.1730 cmꢂ1, which is assigned
to the nCÄO and nCOO. In contrast, the stretching
vibration frequency at ca.1730 cmꢂ1 in the IR spectra
of the complexes becomes weaker than that of the
corresponding free ligands, which implies the two
carbonyl groups have chelated with the metal ion [9].
The IR spectra of the complexes appear absorption at
ca. 2080 and 2010 cmꢂ1, which are the characteristic of
Scheme 2. A practical and facile synthesis of 7.
synthesis of 7 was undertaken using the available 3-
chloropentane-2,4-dione and the sodium 4-hydroxy-
benzoate solid in dry DMF at 50 8C overnight, the
sodium 4-hydroxybenzoate was obtained nearly stio-
chio-metrically by the reaction of 4-hydroxybenzoic acid
with the aqueous solution of NaOH. It’s unnecessary to
use any phase transfer catalyst and protecting reagent in
Scheme 2, all the reactions are operated simply and in
mild conditions, the total yield is about 80% which is
nearly two times of Serrano’s method.
The compound 2,4-dioxo-3-pentyl 4-hydroxycinna-
mate 8 is another key intermediate in the synthesis of
g-substituted b-diketone, it was obtained in good yield
using the similar procedure to prepare the compound 7.
The route to synthesize 8 is outlined in Scheme 3. The
compound 4-hydroxycinnamic acid was obtained ac-
cording to the literature reported previously [13].
The synthesis of 1a, 2a and 3a is outlined in Scheme 4.
This method seemed to be the most facile for prepara-
tion of the compounds with the general structures 1a, 2a
and 3a. Compounds 9 [14], 10 [15,16] were refluxed with
SOCl2 to give the compounds 11 and 12, respectively,
which were then reacted with 7 or 8 to obtain 1a, 2a and
3a in excellent yield. The overall reaction sequence was
carried out simply without chromatographic purifica-
tion.
the carbon monoxide (CO) stretching region [19].
1
From the H-NMR data of the compounds 1aÁ
/
5a, it
3a and 5a exist in both of keto form
and enol form in the solution of CDCl3 (Chart 2). The
1H-NMR spectra for 1aÁ
3a and 5a show a signal (d) at
is found that 1aÁ
/
/
ca. 14.50 ppm due to the enolic proton, a signal at 2.10
ppm for the CH3 proton in the enol form. While, the
signals at ca. 5.71 and 2.37 ppm are assigned to the CH
and CH3 protons in the keto form, respectively.
The UVÁ
complexes 1bÁ
The UVÁvis data in Table 1 show that the lmax of 1aÁ
5a and 1bÁ5b decrease according to the order: 4a,4bꢀ
2a,2bꢀ1a,1bꢀ3a,3bꢀ4a,4b. This may be explained by
the structures of the compounds. As to the compounds
1aÁ3a,5a and 1bÁ3b,5b, the bridging groups between
the two benzene rings are ÃCHÄCHCO2Ã, ÃCO2Ãand
NÄNÃ, respectively, while the compounds 4a,4b have
the ÃCH2OÃ as the bridging group. ÃCHÄCHCO2Ã, Ã
CO2Ã and ÃNÄNÃ are all unsaturated groups which
can be conjugated with the benzene rings and make a
long conjugated structure. In contrast, the ÃCH2OÃ is a
/
vis data of the ligands 1aÁ
/
5a and the
/5b are summarized in Table 1.
/
/
/
/
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/
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/
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/
/
/
Ã
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/
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/
The synthesis of 4a is outlined in Scheme 5, which was
carried out by the reaction of the commercially available
saturated group which is disadvantageous to form long
conjugated system, so the lmax of 4a,4b are the shortest
Scheme 3. Synthesis of 8.

88
J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á93
/
and cooling. The optical, thermal, and thermodynamic
data of the new b-diketones 1aÁ5a are given in Table 2.
/
From Table 2, it is found the following results: (i) the
b-diketones 1a,2a,3a and 5a are all mesogens while 4a
does not display mesophism; (ii) the b-diketone 5a
exhibits two enantiotropic phases (N and Sc), the
temperature range of mesophase is from 78.5 to
184.5 8C, which is the widest among the compounds
1a,2a,3a and 5a; (iii) the b-diketone 2a displays two
monotropic phases (N and Sc) and the mesomorphic
temperature range is about 40 8C,while 1a and 3a both
have one monotropic phase (N) and a narrow meso-
Scheme 4. Synthesis of 1a, 2a, 3a.
among all the compounds. On basis of the lmax of the
compounds 1aÁ3a,5a and 1bÁ3b,5b, we can find that
the conjugation of the bridging groups X increase
according to the order ÃCO2Ã CHÄCHCO2Ã
NÄNÃ. By comparison the lmax of the ligands and the
/
/
/
/
B
/
Ã
/
/
/
B
/
Ã
/
/
/
corresponding complexes, it is found that the lmax of the
complexes are larger than that of the corresponding
ligands. The formation of the six-membered metalacycle
extends the conjugated system because of its aromati-
city, which may explain the change of the lmax between
the ligands and the complexes.
Chart 2.
2.2. Mesomorphism
The textures of the mesophases were studied with a
Nikon polarizing microscope equipped with a hot stage.
All mesophases had been identified according to the
textures observed by optical microscopy [20,21]. The b-
diketones 1a and 3a both exhibit one monotropic phase
(N), and 2a display two monotropic phases (N and Sc),
while 5a exhibit two enantiotropic phases (N and Sc);
The complexes 1b,3b exhibit one enantiotropic phase
(Sc), and 2b displays one enantiotropic smectic A phase.
The typical texture of the ligands and the complexes are
Table 1
The UVÁ
/
vis data of 1aÁ
/
5a and 1bÁ
/
5b
Compound lmax (nm) omax (dm3 molꢂ1 cmꢂ1) (CHCl3) log omax
1a
2a
3a
4a
5a
1b
2b
3b
4b
5b
320.2
321.6
287.4
263.6
361.5
321.0
323.0
288.0
267.5
363.2
28 183
41 687
26 915
20 417
29 054
31 623
47 863
30 651
28 184
31 248
4.45
4.62
4.43
4.31
4.46
4.50
4.68
4.48
4.45
4.49
shown in Figs. 1Á3.
/
The transition temperatures were measured by differ-
ential scanning calorimetry using DSC-7 instrument
operated at a scanning rate of 5 8C minꢂ1 on heating
Scheme 5. Synthesis of 4a.
Scheme 6. Synthesis of 5a.

J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á
/93
89
Table 2
Optical, thermal and thermodynamic data of the g-substituted b-
diketones
Compound
Transition
Temperature (8C)
DH (kJ molꢂ1
)
1a
CÁ
IÁ
NÁ
CÁ
IÁ
NÁ
ScÁ
CÁ
IÁ
NÁ
CÁ
CÁ
NÁ
ScÁ
/
I
108.62
73.84
54.92
126.8
106.8
98.7
43.66
/
N
ꢂ
/
2.49
/
C
ꢂ
/
0.078
2a
3a
/I
47.48
/
N
ꢂ
/
0.53
0.45
4.11
/
Sc
ꢂ
/
/C
68.9
ꢂ/
/I
66.52
52.39
48.36
62.30
78.5
18.12
/
N
ꢂ
/
0.37
/
C
ꢂ
/
1.22
Fig. 1. Texture of the ligand 1a under crossed polarizers, 68 8C, upon
cooling run, ꢃ250 N phase.
4a
5a
/I
42.08
46.23
/
/N
/
Sc
138.7
184.5
ꢂ
/
0.74
/I
ꢂ
/
0.61
the bridging group is an azo, an ester or an acrylic ester,
the aromatic conjugation can be extended to the b-
diketone, and this fact favors molecular polarizability,
thus increasing molecular interactions and consequently
promoting liquid crystal behavior. The conjugation of
the bridging group increases according to the order Ã
/
CO2Ã CHÄCHCO2Ã NÄNÃ, which may explain
/
B
/
Ã
/
/
/
B
/
Ã
/
/
/
the different liquid crystal behaviors of the b-diketones
1a,2a,3a and 5a. The conjugation of the bridging groups
may increase the molecular rigidity and planarity, the
intermolecular interactions and the ordered arrange-
ment of molecules increase consequently. All of these
factors are beneficial to form the mesomorphism and
increase the stability of the thermotropic mesogenic
phase. Owing to the most conjugation of the azo group,
5a has the best mesomorphism than that of the 1a,2a
and 3a. By comparison of the mesomorphic properties
of 1a with that of 2a and 3a, we can see that the
compound 2a has not only wider mesogenic temperature
range but also more mesogenic phases than 2a and 3a.
The bridging groups X and Y in compound 1a are two
acrylic ester groups, which are more effective to form
conjugation structure than the ester group; On the other
hand, the length-to-breadth ratio of 2a is greater than
that of 1a or 3a. Both of the factors favor the parallel
molecular organization and form mesomorphism.
Fig. 2. Texture of the complex 2b under crossed polarizers, 120 8C,
upon cooling, ꢃ250 Sc phase.
/
Fig. 3. Texture of the complex 3b under crossed polarizers, 124 8C,
upon heating, ꢃ250 N phase.
/
The optical, thermal and thermodynamic data of the
organometallic complexes are given in Table 3.
morphic temperature range about 20 8C. The meso-
morphic behaviors observed can be explained using
geometrical and electronic factors associated with the
If the mesomorphism of the organometallic com-
plexes are compared with that of the corresponding
organic ligands, we find that the organic ligands
1a,2a,3a all display monotropic phases, whereas the
molecules. From the structures of the compounds 1aÁ4a
/
and 5a, we can see the bridging group X is CH2O, the
corresponding compounds 4a does not display liquid
crystal behaviors. This is because the bridging group
CH2O disrupts the electronic conjugation and cannot
form enough mesogenic core, which is the basic factor to
the formation of mesomorphic phases. In contrast, when
complexes 1bÁ3b all possess enantiotropic phases. Two
/
factors may be attributed to this improvement of
mesomorphic behavior: (i) the chelating ring of the b-
diketone complexes is not only six-membered conjuga-
tion structure but also planar because of its aromaticity,
which may enhance the rigidity and extend the con-

90
J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á
/93
Table 3
The optical, thermal and thermodynamic data of the organometallic
complexes
4. Experimental
4.1. Techniques
Compound
Transition
Temperature (8C)
DH (kJ molꢂ1
)
1b
CÁ
NÁ
CÁ
SA
CÁ
NÁ
CÁ
/
N
101.5
142.4
118.40
128.49
114.6
130.2
111.2
168
18.83
1.71
IR and UVÁ
/
vis spectroscopies were recorded on,
/
I
respectively a NICOLET FT-MX-IE spectrometer in
KBr pellets and UV-2401PC SHIMADZU. The 1H-
NMR spectra were carried on 300 MHz Brucker AC-
P300 spectrometer in CDCl3 solution, with Me4Si as
internal standard, 1H-NMR peak frequencies are
quoted in ppm and coupling constants in Hz. Elemental
analysis was performed with a CARLO ERBA-1106
microanalyzer. The Mass spectra were taken on a
Finnigan MAT4510 spectrometer (70 eV, direct inser-
tion probe).
2b
3b
/
SA
19.00
3.25
ÁI
/
/
N
21.43
2.12
/
I
4b
5b
/
I
29.08
Á/
Á/
jugated system of the complexes; and (ii) the terminal
carbon monoxides in the complexes are strong ligands
which can be easily coordinated with the metal rho-
dium(I) by the dÁ
tions tend to reduce the strength of the CÅ
extend the conjugation of the mesogenic core, which can
be confirmed experimentally by comparing the vibra-
tional spectra of free and coordinated CO. The free
molecule has a stretching frequency nCO
[22], whereas the terminal groups in the complexes 1bÁ
The optical observations were made with a ORTH-
LUX-II POLBK polarizing optical microscope with a
hot stage and TDA temperature controller. The transi-
tion temperatures and enthalpies were measured on a
/
p and pÁ
/
p* interaction. Both interac-
O bond and
/
PerkinÁElmer DSC-7 differential scanning calorimeter
/
with a heating and cooling rate of 5.0 8C minꢂ1. The
apparatus was calibrated with indium (156.6 8C, 3.3 kJ
molꢂ1) and tin (232.1 8C, 7.2 kJ molꢂ1).
ꢀ
2143 cmꢂ1
/
/
5b have nCO at 2080 and 2010 cmꢂ1, which implies that
the CO ligand accepts p-back donation from metal ion
and may give rise to a large dipole moment of the
complexes. Both of the factors lead to the complexes
have not only good conjugation structure, but also great
dipole moments and facilitate the formation of liquid
crystal phases.
4.2. Synthesis
4.2.1. Synthesis of 2,4-dioxo-3-pentyl 4-hydroxybenzoate
(7) (general procedure for 8)
A mixture of 3-chloropentane-2,4-dione (6.73 g, 0.05
mol) and sodium 4-hydrobenzoate (8 g, 0.05 mol) in
anhydrous DMF (60 ml) was stirred at 50 8C for 24 h.
After cooling at room temperature, 200 ml of water was
added and the mixture was extracted twice with CHCl3.
The combined extracts were dried over sodium sulfate.
The solvent was evaporated under reduced pressure, the
We expect the complex 5b has better mesomorphism
than 5a, unfortunately, when 5b was heated above
168 8C before the melting point, it decomposed partly
and didnot appear mesomorphism. The reason that the
complex 4b did not show mesogenic phase is probably
due to the bridging group Ã
/
CH2OÃ/, which disrupts the
conjugation of the molecule.
remainder was chromatographed on silica gel (EtOAcÁ
/
petrodeum ether 1:1) and further purified by recrystalli-
zation in benzene to obtain a white solid. Yield: 79.7%;
m.p. 109.5 8C; nmax (KBr)/cmꢂ1 3500Á
/
3100, 1724, 1613,
1571, 1254, 1169; dH (CDCl3) 13.90, 5.70 (2ꢃ s, 1H),
s, 6H, 2ꢃ
3. Conclusion
/
6.93Á
/
7.98 (m, 4H, ArH), 2.16, 1.97 (2ꢃ
/
/
CH3); m/z (%): 236 (Mꢁ, 4.78), 147 (100); Anal. Found:
C, 60.95; H, 5.11; Calc. for C12H12O5: C, 61.20; H,
5.08%.
General methods for the syntheses of five series of
new g-substituted b-diketones and their corresponding
dicarbonylrhodium(I) complex have been reported. The
mesogenic properties of the ligands and the complexes
have also explored. The results shown that the bridging
group between the two benzene rings affects the liquid
crystal properties of the ligands and the complexes
greatly. The formation of the six-membered metala-
cycles may extend the conjugated system of the com-
plexes, and the terminal CO ligands accepts p-back
donation from Rh(I) which may give rise to a large
dipole moment of the complexes. Both of the factors are
beneficial to form the mesomorphism.
4.2.2. Data for 2,4-dioxo-3-pentyl 4-hydrocinnate (8)
Yield: 76.4%; white powder; nmax (KBr)/cmꢂ1 3366,
1716, 1631, 1605, 1580, 1515, 1266, 1204, 1149, 985; dH
(CDCl3) 14.45, 5.64 (1H, 2ꢃ
2ꢃ d, J 16, ÃCHÄCHÃ), 7.40, 6.85 (4H, 2ꢃ
s, 6H, 2ꢃ CH3); m/z (%): 262
/
s, CH), 7.70, 6.35 (2H,
/
/
/
/
/
d, J 8.0,
ArH), 2.36, 2.05 (2ꢃ
/
/
(Mꢁ, 2.52), 147 (100); Anal. Found: C, 63.88; H, 5.31.
Calc. for C14H14O5: C, 64.12; H, 5.34%.

J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á
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91
4.2.3. Synthesis of 4-[[4-(n-decyloxy)]oxy]benzoic acid
(14)
(16H, m, 8ꢃ CH2), 0.85 (3H, t, J 6.0, CH3); Anal.
Found: C, 72.10; H, 8.13; N, 7.54. Calc. for C23H30N2O3
C, 72.22; H, 7.90; N, 7.33%.
/
To a suspension of the compound 13 (5.65 g, 0.02
mol) in 50 ml of EtOH was added methyl 4-hydro-
xybenzoate (3.04 g, 0.02 mol) and K2CO3 (5.52 g, 0.04
mol) under stirring. The mixture was refluxed for 12 h.
After cooling to room temperature, the mixture was
neutralized to pH 7 with 2 M HCl. The precipitate was
filtered and washed twice with EtOH. The product was
purified by recrystallization in EtOH to give a white
solid. Yield: 62%; white powder; nmax (KBr)/cmꢂ1 2920,
4.2.6. Synthesis of 2,4-dioxo-3-pentyl 4-[[4-(n-
decyloxy)cinnamoyl]oxy] benzoate (1a) (general
procedure for 2a and 3a)
To a solution of the compound 9 (3.04 g, 10 mmol) in
30 ml of anhydrous benzene was added 5 ml of SOCl2
under stirring. The reaction mixture was refluxed for 12
h and concentrated under reduced pressure. The residue
was diluted with anhydrous benzene (40 ml). To this
solution was added the compound 7 (2.36 g, 10 mmol)
and refluxed for 16 h, then the solvent was removed
under reduced pressure, the residue was recrystallized
twice in anhydrous ethanol to give a white solid. Yield:
82%; nmax (KBr)/cmꢂ1 1726, 1630, 1600, 1505, 1268,
2851, 3500Á
8.06, 7.05 (4H, 2ꢃ
d, J 8, ArH), 5.03 (2H, s, ArCH2O), 3.95 (2H, t, J 6.6,
RCH2OAr), 1.85 (2H, m, CH2), 1.35 (14H, m, 7ꢃ
/
2500, 1681, 1608, 1515, 1249; dH (CDCl3)
/
d, J 9.3, ArH), 7.35, 6.89 (4H, 2ꢃ
/
/
CH2), 0.87 (3H, t, J 6.0, CH3). Anal. Found: C, 74.89;
H, 8.56. Calc. for C24H32O4 C, 75.00; H, 8.33%.
1122; UVÁ
(CHCl3): 320.2 (4.45); dH (CDCl3) 8.16Á
ArH), 7.84, 6.45 (2H, 2ꢃ d, J 16, ÃCHÄ
(2H, t, J 6.6, RCH2OAr), 14.05, 5.71 (1H, 2ꢃ
2.37, 2.07 (6H, 2ꢃ s, 2ꢃ CH3), 1.88 (2H, m, CH2), 1.17
/
vis lmax/nm (log o/dm3 molꢂ1 cmꢂ1
6.96 (8H, m,
CHꢂ), 4.00
s, CH),
)
4.2.4. Synthesis of 4-(4-hydroxyphenylazo)benzoic acid
(15)
/
/
/
/
/
In a typical preparation, 20 ml of H2O containing
HCl (9 ml, 12 M, 0.11 mol) was added to the compound
4-aminobenzoic acid (10 g, 0.073 mol). To the resulting
solution, stirred and cooled to 0 8C, an aqueous NaNO2
(5.1 g, 0.074 mol) solution (20 ml) was added dropwise,
and the so-formed diazonium chloride was consecutively
adjusted to pH 8 with an aqueous solution of K2CO3
and then coupled with phenol (6.9 g, 0.73 mol),
dissolved in 40 ml of aqueous NaOH (2.9 g, 0.073
mol) solution. The reaction mixture was stirred for 30
min at 0 8C and allowed to warm slowly to room
temperature. The mixture was adjusted to pH 6 with an
aqueous HCl solution and the red precipitate was
filtered, washed several times with water and recrystal-
lized in the EtOH to give a red solid. Yield: 53%; nmax
/
/
/
(14H, m, 7ꢃ CH2), 0.88 (3H, t, J 6.0, CH3); m/z (%):
/
522 (Mꢁ, 0.12), 288 (100); Anal. Found: C, 71.46; H,
7.17; Calc. for C31H38O7: C, 71.26; H, 7.28%.
4.2.7. Data for 2,4-dioxo-3-pentyl 4-[[4-(n-decyloxy)-
cinnamoyl]oxy]cinnate (2a)
Yield: 82%; white powder; nmax (KBr)/cmꢂ1 2923,
2853, 1722, 1631, 1600, 1506, 1287, 1252, 1216, 1146;
UVÁ
321.6 (4.62); dH (CDCl3) 14.50, 5.621H, 2ꢃ
7.80, 6.54 (2H, 2ꢃ d, J 16, ÃCHÄCHÃ), 7.72, 6.46 (2H,
2ꢃ d, J 16, ÃCHÄCHÃ), 7.62, 7.23 (4H, 2ꢃ d, J 8,
ArH), 7.52, 6.91 (4H, 2ꢃ d, J 8, ArH), 3.99 (2H, t, J
6.6, RCH2OAr), 2.34, 2.05 (2ꢃ s, 6H, 2ꢃ CH3), 1.78
CH2), 0.87 (t, 3H,
/
vis lmax/nm (log o/dm3 molꢂ1 cmꢂ1) (CHCl3):
/
s, CH),
/
/
/
/
/
/
/
/
/
(KBr)/cmꢂ1 3540Á
2480, 1664, 1610, 1595, 1510; Anal.
/
/
Found: C, 53.58; H, 4.38; N, 11.65. Calc. for
C13H10N2O3 C, 53.71; H, 4.13; N, 11.57%.
/
/
(m, 2H, CH2), 1.24 (m, 14H, 7ꢃ
/
CH3); m/z (%): 548 (Mꢁ, 0.27), 287 (100); Anal. Found:
C, 72.31; H, 7.42. Calc. for C33H40O7: C, 72.26; H,
7.30%.
4.2.5. Synthesis of 4-[4-(n-decyloxy)phenylazo]benzoic
acid (16)
This compound was made by adapting a procedure
reported previously [14]. Three grams (12.4 mmol) of the
compound 15 and 1.0 g (25 mmol) of NaOH were added
to a flask and dissolved in a solution of H2O (40 ml) and
EtOH (20 ml). To this solution was added a solution of
1-bromodecane (2.77 g, 12.5 mmol) in 20 ml of EtOH.
The reaction mixture was refluxed 24 h. After cooled to
the room temperature, the mixture was adjusted to pH 5
using aqueous HCl solution, the red precipitate was
filtered and washed several times with water. The
product was recrystallized twice in ethanol to give a
4.2.8. Data for 2,4-dioxo-3-pentyl 4-[[4-(n-decyloxy)-
benzoyl]oxy]cinnate (3a)
Yield: 68.5%; white powder; nmax (KBr)/cmꢂ1 2927,
2854, 1727, 1635, 1603, 1510, 1258, 1211, 1164, 1064;
UVÁ
287.4 (4.43); dH (CDCl3) 14.50, 5.66 (1H, 2ꢃ
8.15, 7.30 (4H, 2ꢃ d, J 9, ArH), 7.65, 6.99 (4H, 2ꢃ
J 8.7, ArH), 7.80, 6.58 (2H, 2ꢃ d, J 15.9, ÃCHÄCHÃ
4.04 (2H, t, J 6.6, RCH2OAr), 2.37, 2.08 (6H, 2ꢃ s, 2ꢃ
CH2), 0.90
/
vis lmax/nm (log o/dm3 molꢂ1 cmꢂ1) (CHCl3):
/
s, CH),
d,
),
/
/
/
/
/
/
/
/
yellow solid. Yield: 45%; TCÁN
TScÁI
245.9 8C; nmax (KBr)/cmꢂ1 3580Á
1605, 1502, 1285, 1250, 1140; dH (CDCl3) 8.10Á
(8H, m, ArH), 4.05 (2H, t, J 6.6, RCH2OAr), 1.57Á
ꢀ
/
143.7, TNÁSc
ꢀ/181.1,
CH3), 1.85 (2H, m, CH2), 1.30 (14H, m, 7ꢃ
/
ꢀ
/
/2570, 1684,
(3H, t, J 6.0, CH3); m/z (%): 522 (Mꢁ, 0.93), 121 (100);
Anal. Found: C, 71.11; H, 7.38; Calc. for C31H38O7: C,
71.26; H, 7.28%.
/
6.90
1.20
/

92
J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á93
/
4.2.9. Synthesis of 2,4-dioxo-3-pentyl 4-[[4-(n-
decyloxy)benzyl]oxy]benzoate (4a) (general procedure
for 5a)
Ã
/
CHÄ
(2H, t, J 6.6, RCH2OAr), 2.14 (6H, s, 2ꢃ
(2H, m, CH2), 1.26 (14H, m, 7ꢃ CH2), 0.86 (3H, t, J
/
CHÃ
/
), 7.58, 7.00 (4H, 2ꢃ
/
d, J 8.4, ArH), 4.10
/
CH3), 1.78
/
To a suspension of (3.68 g, 10 mmol) in anhydrous
DMF (30 ml) was added KOH (0.56 g, 10 mmol), the
mixture was stirred at 80 8C for 3 h, then 3-chloro-2,4-
pentanedione (1.25 ml, 11 mmol) was added to the
above mixture and stirred over night at 50 8C. After it
cooled to ambient temperature, 100 ml water was added
to the reaction mixture and the mixture was extracted
three times with CHCl3. The combined extracts were
washed with water for three times and then dried with
sodium sulfate. The solvent was evaporated under
reduced pressure and the residue was purified by
chromatography on silica gel using ethyl acetate:
6.0, CH3); Anal. Found C, 57.92; H, 5.59; Calc. for
C33H37RhO9: C, 58.23; H, 5.44%.
4.2.12. Data for dicarbonyl-2,4-dioxo-3-pentyl 4-[[4-(n-
decyloxy)cinnamoyl]oxy] cinnatorhodium(I) (2b)
Yellow solid, yield: 75.3%; nmax (KBr)/cmꢂ1 2925,
2860, 2081, 2009, 1723, 1631, 1601, 1509, 1473, 1253,
1139; UVÁ
(CHCl3): 323.0 (4.68); dH (CDCl3) 8.20, 7.42 (4H, 2ꢃ
d, J 8.8, Ar), 7.82, 6.50 (2H, 2ꢃ d, J 16, ÃCHÄCHÃ),
7.68, 6.48 (2H, 2ꢃ d, J 16, ÃCHÄCHÃ), 7.56, 6.94 (4H,
2ꢃ d, J 8.4, Ar), 4.05 (2H, t, J 6.6, RCH2OAr), 2.10
(6H, s, 2ꢃ CH3), 1.76 (2H, m, CH2), 1.26 (14H, m, 7ꢃ
/
vis lmax/nm (log o/dm3 molꢂ1 cmꢂ1
)
/
/
/
/
/
/
/
/
/
/
petroleum ether (60Á90 8C) (1:2) as eluant. The products
/
/
/
were recrystallized from EtOH to give a white needle
crystal. Yield: 72.8%; nmax (KBr)/cmꢂ1 2920, 2853,
CH2), 0.88 (3H, t, J 6.0, CH3); Anal. Found: C, 59.72;
H, 5.43. Calc. for C35H39RhO7: C, 59.49; H, 5.52%.
1728, 1711, 1607, 1514, 1246, 1168; UVÁ
(log o/dm3 molꢂ1 cmꢂ1) (CHCl3): 263.6 (4.31); dH
(CDCl3) 8.05, 6.89 (4H, 2ꢃ d, J 9.6, ArH), 7.32, 7.01
(4H, 2ꢃ d, J 8.8, ArH), 5.67 (1H, s, CH), 5.04 (2H, s,
ArCH2OAr), 3.94 (2H, t, J 6.6, RCH2OAr), 2.37 (6H, s,
/
vis lmax/nm
4.2.13. Data for dicarbonyl-2,4-dioxo-3-pentyl 4-[[4-(n-
decyloxy)benzoyl]oxy] cinnatorhodium(I) (3b)
/
/
Yellow solid, yield: 72.8%; nmax (KBr)/cmꢂ1 2082,
2009, 1725, 1634, 1603, 1585, 1511, 1474, 1265, 1148;
2ꢃ
/
CH3), 1.79 (2H, m, CH2), 1.27 (14H, m, 7ꢃ CH2),
/
UVÁ
288.0 (4.48); dH (CDCl3) 8.12, 7.30 (4H, 2ꢃ
Ar), 7.88, 6.56 (2H, 2ꢃd, J 16, ÃCHÄCHÃ), 7.62, 6.96
(4H, 2ꢃ d, J 8.4, Ar), 4.03 (2H, t, J 6.6, RCH2OAr),
2.07 (6H, s, 2ꢃ CH3), 1.80 (2H, m, CH2), 1.22 (14H, m,
7ꢃ CH2), 0.87 (3H, t, J 6.0, CH3); Anal. Found: C,
/
vis lmax/nm (log o/dm3 molꢂ1 cmꢂ1) (CHCl3):
0.87 (3H, t, J 6.0, CH3); m/z (%): 482 (Mꢁ, 0.78), 366
(76.51), 57 (100); Anal. Found C, 72.06; H, 7.80; Calc.
for C29H38O6: C, 72.20; H, 7.88%.
/
d, J 8.8,
/
/
/
/
/
/
4.2.10. Data for 2,4-dioxo-3-pentyl 4-[4-(n-
decyloxy)phenylazo]benzoate (5a)
Yield: 60%; red solid; nmax (KBr)/cmꢂ1 2957, 2865,
/
58.41; H, 5.53. Calc. for C31H37O7Rh: C, 58.23; H,
5.44%.
1730, 1630, 1598, 1505, 1260, 1255, 1140; UVÁ
nm (log o/dm3 molꢂ1 cmꢂ1) (CHCl3): 361.5 (4.46); dH
(CDCl3) 14.45, 5.70 (1H, 2ꢃ s, CH), 8.20Á7.10 (8H, m,
ArH), 4.15 (2H, t, J 6.6, RCH2OAr), 2.38, 2.05 (6H,
2ꢃ s, 2ꢃ CH3), 1.87 (2H, m, CH2), 1.18 (14H, m, 7ꢃ
/vis lmax/
4.2.14. Data for dicarbonyl-2,4-dioxo-3-pentyl 4-[[4-(n-
decyloxy)benzyl]oxy]benzoato-rhodium(I) (4b)
Yellow solid; yield: 72.3%; nmax (KBr)/cmꢂ1 2081,
/
/
/
/
/
2008, 1734, 1609, 1585, 1472, 1245, 1151; UVÁ
nm (log o/dm3 molꢂ1 cmꢂ1) (CHCl3): 267.5 (4.45); dH
(CDCl3) 8.12, 6.90 (4H, 2ꢃ d, J 9.6, Ar), 7.30, 7.04
(4H, 2ꢃ d, J 8.8, Ar), 5.10 (s, 2H, ArCH2OAr), 4.03
(2H, t, J 6.6, RCH2OAr), 2.16 (6H, s, 2ꢃ CH3), 1.76
(2H, m, CH2), 1.24 (14H, m, 7ꢃ CH2), 0.86 (3H, t, J
/
vis lmax/
CH2), 0.86 (3H, t, J 6.0, CH3); Anal. Found: C, 70.17;
H, 7.81; N, 5.74. Calc. for C28H36N2O5: C, 69.98; H,
7.55; N, 5.83%.
/
/
/
4.2.11. Synthesis of dicarbonyl-2,4-dioxo-3-pentyl-4-[4-
(n-decyloxy)cinnamoyl]oxy] benzoatorhodium(I) (1b)
/
6.0, CH3); Anal. Found: C, 58.36; H, 5.87. Calc. for
C31H37O7Rh: C, 58.13; H, 5.78%.
(general procedure [9] for 2bÁ5b)
/
A mixture of acetone solution of 1a (109.6 mg, 0.2
mmol) and [RhCl(CO)2]2 [23] (38.9 mg, 0.1 mmol) with
excess of solid barium carbonate was stirred under an
argon atmosphere at room temperature for 2 h. Then
the reaction mixture was filtered to remove the pre-
cipitate, the filtrate was evaporated under reduced
pressure. The reminder was purified by silica gel using
chloroform as eluant and further purified by recrystalli-
zation in EtOH to give a yellow solid. Yield: 79.9%; nmax
(KBr)/cmꢂ1 2930, 2854, 2082, 2009, 1725, 1634, 1603,
4.2.15. Data for dicarbonyl-2,4-dioxo-3-pentyl 4-[4-(n-
decyloxy)phenylazo] benzoato-rhodium(I) (5b)
Red solid; yield: 75.8%; nmax (KBr)/cmꢂ1 2950, 2860,
2080, 2012, 1737, 1605, 1505, 1585, 1417, 1260, 1250,
1145; UVÁ
(CHCl3): 363.2 (4.49); dH (CDCl3) 8.25Á
ArH), 4.00 (2H, t, J 6.6, ArOCH2), 2.07 (6H, s, 2ꢃ
CH3), 1.90 (2H, m, CH2), 1.22 (14H, m, 7ꢃ CH2), 0.83
/
vis lmax/nm (log o/dm3 molꢂ1 cmꢂ1
)
/6.95 (8H, m,
/
/
1511, 1265, 1208, 1148; UVÁ
molꢂ1 cmꢂ1) (CHCl3): 321.0 (4.50); dH (CDCl3) 8.30,
7.38 (4H, 2ꢃ d, J 8.8, ArH), 7.90, 6.56 (2H, 2ꢃd, J 16,
/
vis lmax/nm (log o/dm3
(3H, t, J 6.0, CH3); Anal. Found: C, 56.08; H, 5.85; N,
4.66; Calc. for C30H35N2RhO7: C, 56.43; H, 5.48; N,
4.39%.
/
/

J. Han et al. / Journal of Organometallic Chemistry 672 (2003) 86Á
/93
93
[9] W. Wan, W. Guang, K. Zhao, W. Zheng, L.F. Zhang, J.
Organomet. Chem. 557 (1998) 157.
Acknowledgements
[10] W. Wan, K.Q. Zhao, W. Wuan, L.F. Zhang, Acta Chim. Sin. 56
(1998) 278.
We thank for the National Nature Science Founda-
tion (2927024, 29673041).
[11] S.T. Trzaska, T.M. Swager, Chem. Mater. 10 (1998) 438.
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