Synthesis and characterization of ruthenium(II) complexes of 2'- hydroxychalcones

Article abstract of DOI:10.1039/a809005j

Reaction of cis-RuCl₂(DMSO)₄, with the potassium salts of 2'- hydroxychalcones L leads to the stable complexes RuL₂(DMSO)₂. For each ligand L three isomers of each bis(dimethyl sulfoxide)bis(chalconato)ruthenium

Full text of DOI:10.1039/a809005j

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Synthesis and characterization of ruthenium(II) complexes of
2º-hydroxychalcones
Artur M. S. Silva,*a Jose A. S. Cavaleiro,a Georges Tarragob and Claude Marzinb
a Chemistry Department, University of Aveiro, 3810 Aveiro, Portugal. Fax: ]351 34 370084;
e-mail: arturs=dq.ua.pt
b Equipe Chimie Supramoleculaire, L MPM, (CNRS UMR 5635), Universite Montpellier II,
Place E. Bataillon, 34095 Montpellier cedex 5, France
Received (in Strasbourg, France), 17th November 1998, Accepted 7th January 1999
Reaction of cis-RuCl (DMSO) with the potassium salts of 2@-hydroxychalcones L leads to the stable complexes
2
4
RuL (DMSO) . For each ligand L three isomers of each bis(dimethyl sulfoxide)bis(chalconato)ruthenium(II)
2
2
complex were found; in two of them the two chalconates and the two DMSO ligands are equivalent, while in the
third one the chalconates and DMSO ligands are inequivalent. Only two isomers of the RuL (DMSO) complex
were obtained by the reaction of cis-RuCl (DMSO) with the potassium salt of the 2@-hydroxy-3,4,4@,5,6@-
pentamethoxydihydrochalcone. One of these isomers was also obtained by the reduction of the appropriate
bis(dimethyl sulfoxide)bis(chalconato)ruthenium(II) complex. All these complexes were fully characterized by
extensive NMR studies, mass spectrometry and elemental analysis. The unequivocal stereochemistry of each
RuL (DMSO) complex was established by NOESY experiments.
2
2
2
4
2
2
Chalconoids constitute an important class of naturally
occurring Ñavonoid compounds exhibiting a wide spectrum of
biological activities, which include potential applications as
artiÐcial sweeteners, new drugs or agrochemicals.1v8 The term
chalconoid has been used to designate the whole family of
compounds possessing a 1,3-diarylpropane skeleton, which
can be modiÐed in the propane chain by the presence of an
oleÐnic bond, keto and/or hydroxyl groups. The most
common and widespread compounds of the chalconoid group
are the chalcones, which possess a 1,3-diaryl-2-propen-1-one
carbon framework.1,3,5 However, there are also other impor-
tant derivatives of this family, such as the dihydrochal-
cones.2,8
The antioxidant activity of Ñavonoids is basically associated
with the reduction or inhibition of lipid peroxidation, which is
strongly related with aging and carcinogenesis, by their ability
to act as free radical scavengers and also to chelate transition
metals ions, in order to avoid the involvement of iron and
copper ions in the initiation of free radical reactions.9,10 Sub-
stances that can limit lipoperoxidation processes can be of
considerable interest for therapeutic research on diseases
in which free radicals are implicated. Having in mind these
tal analysis, of the new bis(dimethyl sulfoxide)-
bis(chalconato)ruthenium(II)
sulfoxide)bis(dihydrochalconato)ruthenium(II)
which are respectively formed by
RuCl (DMSO) with chalconates L1ÈL3 and dihydrochalcon-
5È7
and
bis(dimethyl
complexes,
treating cis-
8
2
4
ate L4 (Scheme 1). The complex bis(dimethyl sulfoxide)bis(di-
hydrochalconato)ruthenium(II) 8h was also obtained by
reduction of the corresponding bis(dimethyl sulfoxide)bis-
(chalconato)ruthenium(II) complex 7i with ammonium formate
and Pd/C (10%).
Results and discussion
Synthesis and characterization of bis(dimethyl
sulfoxide)bis(chalconato or dihydrochalconato)ruthenium(II)
complexes
We have followed the complexation of chalconates with
ruthenium(II) by 1H NMR as in our previous work.14 A solu-
tion of 2@-hydroxy-3,4,4@,5,6@-pentamethoxychalcone
3 in
methanol-d was treated with a molar equivalent of an
4
aqueous solution of sodium hydroxide (some drops of
dimethyl sulfoxide-d were added to homogenize the reaction
6
facts
and
that
the
2@-hydroxychalcone
and
2@-
mixture) and was reÑuxed for 15 min. By 1H NMR analysis, it
hydroxydihydrochalcone Ñavonoids present antioxidant activ-
ity,7,11 it is of interest to study the complexation of these
compounds with transition metal ions.
was possible to observe the presence of a small amount of
starting material and signals corresponding to the expected
3,4,4@,5,6@-pentamethoxychalconate L3. However, it may be
noticed that the intensity of the integral of the vinylic proton
resonance of this chalconate L3 is almost half of that corre-
sponding to H-2,6 and decreases after more reÑux time, sug-
gesting that a-deuteriation has taken place.15 To improve the
synthesis of the chalconates L1ÈL3, the corresponding 2@-
hydroxychalcones 1È3 were treated with a molar equivalent of
potassium tert-butoxide in di†erent solvents. After several
Studies on 2@-hydroxychalcone complexation with some
transition metal ions (CoII, NiII, CuII, PtII and PdII) led to
stable complexes, with a square planar conÐguration, in a
1:2 metal:ligand stoichiometry.12,13 Rao et al. have also
reported the synthesis and characterization of complexes of
the diamagnetic transition metal ion RuII with 2@-
hydroxychalcones.13 These complexes were obtained by treat-
ing cis-RuCl (DMSO) with appropriate chalcones under
assays, dimethyl sulfoxide-d , a solvent without exchangeable
2
4
6
reÑux in a 3 : 1 mixture of toluene : methanol. In spite of the
diamagnetic properties of such ruthenium(II) species, the com-
plexes obtained were not characterized by NMR.
deuterium atoms, was chosen for NMR studies and anhy-
drous tert-butyl alcohol for the synthesis of ruthenium(II) com-
plexes of chalconates L1ÈL3.
In this paper we will report the synthesis and character-
ization, by 1H and 13C NMR, mass spectrometry and elemen-
Treatment of cis-RuCl (DMSO) with two molar equiva-
2
4
lents of chalconates L1ÈL3 gave the corresponding
New J. Chem., 1999, 329È335
329

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Scheme 1.
com-
bis(dimethyl
plexes 5È7. For each chalconate L1ÈL3 three isomers have
been obtained for each bis(dimethyl
sulfoxide)bis(chalconato)ruthenium
In the NOESY spectra of chalconates L1ÈL3, NOE cross
peaks were observed between the resonances of H-2,6 and
those of H-a and H-b. No cross peaks were observed between
sulfoxide)bis(chalconato)ruthenium(II) complex, which have
been separated by thin layer chromatography and identiÐed in
each case as h (higher), i (intermediate) and l (lower), following
the signal of H-a and that of H-6@ in L1 or of 6@-OCH in L2
3
and L3, which indicates that these protons are not spatially
close. In 4-methoxychalconate L1, due to the repulsive e†ect
between the anion and the carbonyl group, there is rotation
around the C1@wCxO bond, which places the anion and H-a
in close proximity (Scheme 2). Due to this spatial proximity
H-a is strongly deshielded (]1.05 ppm) compared to H-a in
the corresponding 2@-hydroxychalcone 1. In the case of chal-
conates L2 and L3, there is also a repulsive e†ect between the
anions and the carbonyl groups with a consequent rotation
around the C1@wCxO bond. However, in this case the steric
hindrance due to the presence of the 6@-methoxyl group
implies that the A ring of these compounds will be perpen-
dicular to the other part of the molecule (Scheme 3). As a
consequence, H-a does not feel the through-space deshielding
e†ect of the 6@-methoxyl oxygen, which is signiÐcant in the
corresponding 2@-hydroxychalcones 2,3. These e†ects are
their R values in thin layer chromatographic analysis. In the
f
case of 3,4,4@,5,6@-pentamethoxydihydrochalconate L4 only
two isomers, 8h and 8l, of the corresponding bis(dimethyl
sulfoxide)bis(dihydrochalconato)ruthenium(II) complex have
been obtained and separated by thin layer chromatography.
The bis(dimethyl sulfoxide)bis(3,4,4@,5,6@-pentamethoxydihy-
drochalconato)ruthenium(II) complex 8h was also obtained by
treatment of bis(dimethyl sulfoxide)bis(3,4,4@,5,6@-pentame-
thoxychalconato)ruthenium(II) 7i with ammonium formate
and Pd/C (10%). In this transformation hydrogenation of the
chalconate ligand double bonds took place.
The 1H and 13C NMR spectral data of the 2@-
hydroxychalcones 1È3, corresponding chalconates L1ÈL3 and
their ruthenium(II) complexes 5È7 are given in Tables 1 and 2.
The assignments of all proton and protonated carbon reso-
nances were determined by 2D NMR experiments (COSY,
NOESY, HETCOR and HMBC, Heteronuclear Multiple-
Bond Correlation).
As shown in Table 1, the resonances corresponding to the A
ring protons of chalconates L1ÈL3 are shielded relative to
those of the corresponding 2@-hydroxychalcones 1È3, because
of the increased electronic density e†ects on all the protons of
the chalconate A ring due to the anion charge, which most
strongly a†ects the para position. The H-a and H-b reso-
nances in 1È3 appeared as two doublets. The coupling constant
(3J
15.5È15.7 Hz) indicates the trans conÐguration of the
HavHb
vinylic system. The unequivocal assignment of these reso-
nances were made by using HMBC experiments, in which the
resonance of H-a presents connectivities with CxO, C-1 and
C-1@ and that of H-b with CxO, C-1 and C-2,6. In the
NOESY spectra of compounds 1È3, NOE cross peaks were
observed between the resonances of H-b and H-2,6 and also
between H-a and H-2,6 and H-6@, for 5, or 6@-OCH , for 6 and 7.
3
2@-Hydroxychalcones have a strong hydrogen bond involv-
ing the carbonyl and the proton of the 2@-hydroxyl groups,
inducing a delocalization along the a,b-unsaturated keto
moiety of the molecule. In the chalconates L1ÈL3 this hydro-
gen bond does not exist and, as a consequence, this delocal-
ization e†ect is decreased and H-b is shielded (D [0.6 ppm).
Scheme 2.
330
New J. Chem., 1999, 329È335

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Table 1 1H chemical shiftsa,b of the 2@-hydroxychalcones 1È3 and 2@-hydroxydihydrochalcone 4, their chalconates L1ÈL3 and dihydrochalconate
L4 and of the corresponding bis(dimethyl sulfoxide)bis(chalconato or dihydrochalconato)ruthenium(II) complexes 5È8
OH-2@
H-3@
H-4@
H-5@
H-6@
H-a
H-b
H-2,6
H-3,5
S-DMSO
1
12.95
(s)
È
7.02
(dd; 8.4, 1.2)
6.23
(d; 8.6)
6.55
(d; 8.4)
6.73
(dd; 8.4, 1.0)
6.94
(dd; 8.6, 1.0)
6.98
(d; 8.0)
6.61
(d; 7.6)
6.01
(d; 8.2)
5.99
(d; 7.9)
6.32
(dd; 8.6, 0.7)
6.53
(dd; 8.6, 0.8)
6.59
(dd; 8.6, 0.8)
6.11
(d; 2.4)
5.36
(s; broad)
5.66
(d; 2.1)
5.88
(d; 2.3)
6.05
(d; 2.3)
6.11
(d; 2.3)
6.08
(d; 2.2)
6.21
(s; broad)
5.98
(d; 2.3)
6.04
(d; 2.3)
5.59
(s)
7.48
(dt; 7.8, 1.7)
6.86
(dt; 7.4; 1.9)
7.13
(t; 7.9)
7.12
(dt; 7.7, 1.6)
7.18
(dt; 7.7, 1.6)
7.24
(dt; 7.6, 1.6)
7.35
(t; 7.6)
6.75
(t; 8.2)
6.90
(dd; 8.4, 7.9)
6.96
(dd; 8.6, 8.0)
7.05
(dd; 8.6, 7.7)
7.12
(dd; 8.6, 7.8)
È
6.93
7.92
(dd; 7.6, 1.7)
7.49
(dd; 7.6, 1.9)
7.73
(d; 7.9)
7.72
(dd; 8.6, 1.6)
7.81
(dd; 8.6, 1.6)
7.65
(dd; 7.5, 1.6)
È
7.54
(d; 15.5)
8.60
(d; 15.9)
7.42
(d; 16.0)
7.35
(d; 15.0)
7.46
(d; 16.0)
7.34
(d; 15.3)
7.77
(d; 15.7)
6.99
(d; 16.0)
7.38
(d; 15.6)
7.37
(d; 15.4)
7.40
(d; 15.6)
7.34
(d; 15.5)
7.82
(d; 15.5)
7.32
(d; 15.8)
7.37
(d; 16.0)
7.29
(d; 15.3)
7.35
(d; 15.5)
7.36
(d; 15.4)
3.31
(t; 7.4)
3.35
(t; 7.4)
3.11
(m)
3.27
(m)
7.90
(d; 15.5)
7.36
(d; 15.9)
7.56
(d; 16.0)
6.96
(d; 15.0)
7.66
(d; 16.0)
7.13
(d; 15.3)
7.81
(d; 15.7)
7.18
(d; 16.0)
7.49
(d; 15.6)
7.07
(d; 15.4)
7.58
(d; 15.6)
7.19
(d; 15.5)
7.68
(d; 15.5)
7.11
(d; 15.8)
7.39
(d; 16.0)
7.02
(d; 15.3)
7.48
(d; 15.5)
7.08
(d; 15.4)
2.94
(t; 7.4)
3.10
(t; 7.4)
2.48
(m)
2.88
(m)
7.62
(d; 8.6)
7.56
(d; 8.7)
7.57
(d; 8.6)
7.34
(d; 8.8)
7.62
(d; 8.8)
7.36
(d; 8.8)
7.57
(d; 8.1)
7.51
(d; 8.7)
7.51
(d; 8.7)
7.33
(d; 8.7)
7.55
(d; 8.7)
7.38
(d; 8.8)
6.84
(s)
6.82
(s)
6.78
(s)
6.63
(s)
6.81
(s)
6.66
(s)
6.46
(s)
6.54
(s)
6.31
(s)
6.95
(d; 8.6)
6.96
(d; 8.7)
6.93
(d; 8.6)
6.84
(d; 8.8)
6.94
(d; 8.8)
6.85
(d; 8.8)
6.93
(d; 8.1)
6.93
(d; 8.7)
6.90
(d; 8.7)
6.84
(d; 8.7)
6.91
(d; 8.7)
6.85
È
È
È
(ddd; 7.8, 7.6, 1.2)
5.88
(dd; 7.6, 7.4)
6.46
(t; 7.9)
6.44
(dt; 7.7, 1.0)
6.48
(dt; 7.7, 1.0))
6.45
(dd; 7.6, 7.5)
6.42
(d; 7.6)
5.74
(t; 8.2)
5.97
(d; 8.4)
5.96
(d; 8.0)
5.99
(d; 7.7)
5.98
(d; 7.8)
5.96
(d; 2.4)
5.16
(s; broad)
5.56
(d; 2.1)
5.59
(d; 2.3)
5.64
L1
5h
5i
È
È
2.97; 3.35
(2 s)
2.90; 3.22
(2 s)
3.19; 3.37
(2 s)
3.05; 3.32
(2 s)
5l
2
È
13.32
(s)
È
È
L2
6h
6i
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
2.99; 3.29
(2 s)
2.87; 3.19
(2 s)
3.12; 3.34
(2 s)
3.02; 3.29
(2 s)
6l
3
(d; 8.8)
È
14.36
(s)
È
È
L3
7h
7i
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
È
3.01; 3.28
(2 s)
2.93; 3.15
(2 s)
3.15; 3.34
(2s)
3.06; 3.28
(2 s)
(d; 2.3)
5.62
(d; 2.3)
5.93
(d; 2.2)
5.80
(s; broad)
5.61
(d; 2.3)
5.65
(d; 2.3)
5.59
7l
4
14.00
(s)
È
È
L4
8h
È
È
È
È
2.77; 3.11
(2 s)
3.11; 3.31
(2 s)
2.82; 3.18
(2 s)
6.37
(s)
6.32
(s)
8l
3.20
(m)
2.77
(m)
(s)
a The resonances of the methoxyl groups are given in the Experimental. b In parentheses is shown the multiplicity of each signal and the
corresponding coupling constants in hertz.
responsible for the shift to lower frequency values ([0.50 to
[0.78 ppm) of the H-a resonance in L2,L3 relative to that in
2@-hydroxychalcones 2,3.
and the corresponding ruthenium(II) complexes 5È7 are similar
to those already reported for 5-hydroxyÑavones, the corre-
sponding Ñavonates and their ruthenium(II) complexes.14
These e†ects are a consequence of the electronic processes
referred to above, and the most a†ected resonances are those
of the A ring, C-a, C-b and of the carbonyl group. The com-
parison of the 13C NMR spectra of 2@-hydroxy-3,4,4@,5,6@-pen-
tamethoxydihydrochalcone 4, the corresponding 3,4,4@,5,6@-
pentamethoxydihydrochalconate L4 and their bis(dimethyl
sulfoxide)bis(3,4,4@,5,6@-pentamethoxydihydrochalconato)-ruth-
enium(II) complexes 8h and 8l allowed us to conclude that the
electronic processes a†ect essentially the resonances of the A
ring and of the carbonyl group.
In the case of 3,4,4@,5,6@-pentamethoxydihydrochalconate
L4, benzene-d was chosen as solvent for the NMR character-
6
ization, because in this solvent no a-deuteriation could occur.
Comparison between the resonances of dihydrochalcone 4
and the corresponding dihydrochalconate L4 is not possible
because the 1H NMR spectra of these two compounds were
recorded in very di†erent solvents.
Upon complexation of chalconates L1ÈL3 the A ring
protons are deshielded (Table 1), as reported in the case of
Ñavonate complexation with ruthenium(II).14 Due to the com-
plexation of chalconates L1ÈL3 as bidentate ligands it is
important to notice that the conformational e†ects referred to
above and shown in Schemes 2 and 3 have now disappeared;
H-a is now shielded ([1.13 to [1.25 ppm) in complex 5 and
deshielded in complexes 6 and 7, but this e†ect is stronger in 6
(]0.35 to ]0.41 ppm).
Structures of the new complexes
Mass spectra and elemental analysis of the synthesized com-
plexes 5È8 suggest their composition as RuL (DMSO)
2
2
(L \ chalconates L1ÈL3 or dihydrochalconate L4). The stereo-
chemistry of these complexes will be discussed from the results
of 1H and 13C NMR spectroscopy, because our attempts to
As shown in Table 2, the e†ects observed in the 13C NMR
spectra of 2@-hydroxychalcones 1È3, their chalconates L1ÈL3
New J. Chem., 1999, 329È335
331

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that in all the synthesized complexes the DMSO ligands are
S-bonded.17
The presence of two unsymmetrical bidentate chalconate or
dihydrochalconate ligands and of two S-bonded DMSO
ligands may give rise to Ðve diastereoisomers of the
ruthenium(II) complexes 5È8, three of which have enantiomers
(forms C, D and E) (Scheme 4). However, in the case of chal-
conates L1ÈL3 and dihydrochalconate L4 only three and two
diastereoisomes have been respectively obtained; their struc-
tures are discussed below.
The 1H NMR spectra of complexes 5h, 6h and 7h (Table 1)
present signals corresponding to two equivalent chalconate
ligands and two other broad signals of equal intensity (6H
each) in the S-bonded DMSO region (2.97È3.35 ppm). The
broadness of these signals and the strong NOE cross peaks
between them, observed in the NOESY spectra, led us to con-
clude that they are due to the resonance of two diastereotopic
methyl groups18 of two equivalent DMSO ligands. This
broadness is due to the 1HÈ1H coupling between the dia-
stereotopic methyl groups on the same DMSO.
Of the Ðve possible isomers of complexes 5h, 6h and 7h
(Scheme 4), the structures corresponding to forms A and E (or
their enantiomer) are ruled out. In form A the two DMSO
ligands are equivalent because of the horizontal plane of sym-
metry, while the vertical plane through the two sulfur atoms
makes the methyl groups on each DMSO equivalent. On the
other hand, in form E the two chalconate and the two DMSO
ligands are inequivalent, because this form has only a C axis
1
of symmetry. Considering these facts and the NOE cross
peaks, observed in the NOESY spectra, between the methyl
proton resonances of the DMSO ligands and that of the H-b
of chalconates, one can establish that the structures of com-
plexes 5h, 6h and 7h are represented by form C (or its
enantiomer).
Scheme 3.
In the NOESY spectra of all the synthesized complexes 5, 6
and 7, NOE cross peaks were observed between the reso-
nances of H-b and those of H-2,6 and also between H-a and
grow single crystals for X-ray analysis were unsuccessful.
The methyl carbon resonances of the DMSO ligands is a
general and reliable criterion to establish their coordination
mode, as S- or O-bonded.16 In our case, these carbon reso-
nances appear at higher frequency values (42.3È44.7 ppm)
H-2,6 and H-6@, for 5, or 6@-OCH , for 6 and 7. These data
3
allowed us to conclude that in these complexes the stereoche-
mistry of the ligands is similar to that of the 2@-
hydroxychalcones 1È3 mentioned above.
than that of free DMSO (40.1 ppm in CDCl ), which indicates
3
Table 2 13C chemical shiftsa of the 2@-hydroxychalcones 1È3 and 2@-hydroxydihydrochalcone 4, their chalconates L1ÈL3 and dihydrochalconate
L4 and of the corresponding bis(dimethyl sulfoxide)bis(chalconato or dihydrochalconato) ruthenium(II) complexes 5È8
C-1@
C-2@
C-3@
C-4@
C-5@
C-6@
CxO
C-a
C-b
C-1
C-2,6
C-3,5
C-4
S-DMSO
1
120.1
125.7
122.9
122.1
123.6
122.8
112.0
118.5
118.6
117.9
118.8
118.7
106.3
113.1
113.5
112.3
113.5
113.0
105.8
110.0
111.4
112.1
112.1
163.6
176.1
171.6
172.3
173.6
175.4
164.8
173.9
173.2
173.8
175.8
176.9
168.8
175.6
175.9
175.9
177.6
178.7
167.6
171.8
175.2
176.5
175.1
118.6
126.2
125.3
125.8
126.5
127.1
110.9
114.3
117.1
118.1
118.6
119.0
93.8
97.8
98.2
99.0
99.4
99.5
93.7
96.7
98.7
136.2
133.2
135.1
134.4
135.2
134.6
135.7
130.0
133.9
133.5
134.1
133.7
166.6
162.7
165.5
165.1
165.5
165.2
166.0
163.5
165.0
165.5
165.5
118.8
107.1
114.0
114.0
114.3
113.8
101.5
92.5
96.2
96.6
96.8
96.5
91.3
81.3
88.7
89.0
89.3
89.3
90.9
89.9
88.6
88.7
88.2
127.4
131.1
131.4
131.2
131.8
131.9
160.9
158.7
161.3
161.2
161.9
161.9
162.8
161.2
162.5
162.3
162.9
163.1
162.7
166.3
163.2
163.5
163.0
193.7
189.5
190.2
187.3
191.6
187.4
194.3
195.1
191.5
188.6
192.9
189.9
192.3
190.9
188.8
185.4
189.9
185.8
204.4
205.3
197.8
202.1
201.6
117.6
128.6
120.6
120.9
121.2
120.6
125.1
128.1
126.1
126.0
126.1
126.3
126.9
134.1
127.9
127.7
128.3
128.1
45.8
145.4
135.9
143.1
143.3
143.4
144.0
143.1
137.7
140.4
140.5
140.9
140.9
142.4
132.3
139.6
139.6
139.6
140.1
31.1
127.4
129.3
128.1
128.0
128.3
128.1
128.0
128.7
128.5
128.4
128.8
128.6
131.1
131.9
131.6
131.5
132.1
131.7
137.5
138.5
135.9
136.1
136.0
129.5
129.2
130.0
129.9
130.1
130.0
130.3
129.4
129.8
129.7
129.9
129.8
105.5
104.6
105.1
104.9
105.1
105.0
105.4
107.4
105.1
105.2
105.2
114.5
114.2
114.5
114.2
114.5
114.3
114.4
114.3
114.3
114.1
114.4
114.2
153.4
153.0
153.4
153.3
153.4
153.3
153.1
154.6
153.0
153.1
153.0
162.0
159.8
161.4
161.1
161.5
161.4
161.5
160.2
161.1
160.9
161.2
161.0
140.0
137.9
139.6
139.4
139.7
139.4
136.2
138.5
137.1
138.1
137.2
È
È
L1
5h
5i
43.5; 44.3
44.0; 44.2
42.4; 44.3
43.5; 44.2
È
5l
2
L2
6h
6i
È
43.4; 44.0
43.9; 44.6
42.3; 44.7
43.9; 44.3
È
6l
3
L3
7h
7i
È
43.7; 44.3
43.9; 44.6
42.6; 44.7
43.9; 44.3
È
7l
4
L4
8h
47.2
44.9
45.7
45.6
32.6
32.3
33.1
33.0
È
43.3; 44.2
42.5; 44.4
43.6; 43.6
99.1
98.0
8l
a The resonances of the methoxyl groups are given in the Experimental.
332
New J. Chem., 1999, 329È335

View Article Online
Scheme 4.
The 1H NMR spectra of complexes 5l, 6l and 7l (Table 1)
also present signals of equivalent chalconate ligands and of
two diastereotopic methyl groups18 of two equivalent DMSO
ligands. In the NOESY spectra of these complexes, NOE
cross peaks between the methyl proton resonances of the two
DMSO ligands and that of the H-3@ of the chalconate were
observed, establishing form D (or its enantiomer) as represent-
ing the structures of complexes 5l, 6l and 7l.
complex 8h as being represented by an analogous form of E
(or its enantiomer) (Scheme 4). The 1H NMR spectrum of
complex 8l presents the signals of two equivalent dihydrochal-
conate ligands and of two diastereotopic methyl groups18 of
two equivalent DMSO ligands. These results and the NOE
cross peaks, observed in the NOESY spectrum, between the
methyl proton resonances of the DMSO ligands and that of
H-b of the dihydrochalconate ligands, led us to establish an
analogous form of C (or its enantiomer) as representing the
structure of complex 8l.
The 1H NMR spectra of complexes 5i, 6i and 7i (Table 1)
present the signals of two inequivalent chalconate ligands and
of four inequivalent methyl groups of two DMSO ligands, as
expected for a molecule belonging to the C symmetry point
group. In the NOESY spectra of these complexes, NOE cross
Experimental
1
Measurements
peaks were observed between the two methyl proton reso-
nances of the DMSO ligand trans to the carbonyl oxygen
(2.90, 3.22 for 5i; 2.99, 3.29 for 6i and 2.93, 3.15 ppm for 7i)
and that of H-3@ of one chalconate ligand and also between
the two methyl proton resonances of the DMSO ligand trans
to the phenoxide (3.19, 3.37 for 5i; 3.12, 3.34 for 6i and 3.15,
3.34 ppm for 7i) and that of H-b of the other chalconate
ligand (Scheme 4). These results led us to conclude that the
structure of complexes 5i, 6i and 7i is represented by form E
(or its enantiomer).
In the 1H NMR spectrum of complex 8h were observed the
signals corresponding to two inequivalent dihydrochalconate
ligands and of four inequivalent methyl groups of two DMSO
ligands (Table 1). These results and their similarity to those of
complexes 5i, 6i and 7i allowed us to establish the structure of
Melting points were determined on a Reichert Thermovar
apparatus Ðtted with a microscope and are uncorrected. 1H
and 13C NMR spectra were recorded in diluted deuteriochlo-
roform solutions (ca. 0.3%), except those of chalconates
(DMSO-d ) and dihydrochalconate (C D ), on a Bruker
6
6 6
AMX 300 spectrometer, at 300.13 and 75.47 MHz, respec-
tively; the chemical shifts are expressed in ppm relative to
tetramethylsilane (TMS) as internal reference. 1H assignments
were made by using 2D COSY and NOESY (mixing time of
800 ms) experiments, while 13C assignments were made using
HETCOR and HMBC (delay for long-range J CÈH couplings
were optimized for 7 Hz) experiments. Electron impact mass
spectra were obtained at 70 eV electron impact ionization
using a VG Autospec Q mass spectrometer. Fast atom bom-
New J. Chem., 1999, 329È335
333

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bardment mass spectra were run on a Jeol JMX DX-33 mass
spectrometer, using 3-nitrobenzyl alcohol as a matrix. Ele-
mental analyses were carried out in the ““Service Central de
Microanalyse du Centre National de la Recherche ScientiÐque
de MontpellierÏÏ. Preparative thin layer chromatography was
tert-butoxide. The reaction mixture was heated at 40 ¡C, with
magnetic stirring and under nitrogen, for 30 min and then 1H
and 13C NMR spectra were recorded. These values are shown
in Tables 1 and 2; however, the proton and carbon assign-
ments of the methoxyl groups are as follows. 1H NMR:
d \ 3.28 (s, 3H, 4@-OCH ), 3.47 (s, 3H, 6@-OCH ), 3.62 [s, 6H,
carried out on silica gel plates (Riedel silica gel 60 DGF ).
254
3
3
Column chromatography was also performed on silica gel
3,5-(OCH ) ], 3.90 (s, 3H, 4-OCH ). 13C NMR: d \ 55.3 (4@-
3 2
OCH ), 55.4 (6@-OCH ), 56.6 [3,5-(OCH ) ], 61.0 (4-OCH ).
3 2
3
(Merck silica gel 60, 70È230 mesh).
3
3
3
Reagents and syntheses
Bis(dimethyl sulfoxide)bis (chalconato)ruthenium (II) com-
plexes 5–7. To solution of the appropriate 2@-
a
cis-RuCl (DMSO) was obtained from Johnson Matthey Alfa
2
4
hydroxychalcone 1È3 (1.0 mmol) in tert-butyl alcohol (10 ml),
potassium tert-butoxide (112 mg, 1.0 mmol) was added. The
mixture was heated at reÑux, with magnetic stirring and under
nitrogen, for 30 min, giving a red clear solution of the chal-
conate anion. cis-RuCl (DMSO) (243 mg, 0.5 mmol) was
Products. All other chemicals and solvents used herein were
obtained from commercial sources and used as received or
dried using standard procedures.
2º-Hydroxychalcones. These were synthesized by known
procedures.19
2
4
then added and the reÑux was continued for the appropriate
time (2 days for 2 and 3, and 6 days for 1).
2@-Hydroxy-4-methoxychalcone 1. (85%), mp 89È91 ¡C (lit.20
95 ¡C). 1H NMR: d \ 3.86 (s, 3H, 4-OCH ). 13C NMR:
Upon cooling, CH Cl (100 ml) was added to the reaction
3
2
2
d \ 55.5 (4-OCH ).
mixture and the organic layer was washed with water (2 ] 100
ml), dried over anhydrous sodium sulfate and the solvent
evaporated to dryness. The obtained residue was chromato-
graphed on several preparative thin layer chromatography
3
2@-Hydroxy-4,6@-dimethoxychalcone 2. (89%), mp 112È
114 ¡C. 1H NMR: d \ 3.85 (s, 3H, 4-OCH ), 3.94 (s, 3H, 6@-
3
OCH ). 13C NMR: d \ 55.4 (6@-OCH ), 55.9 (4-OCH ).
3
3
3
FAB`-MS: m/z (rel. int.) 285 [(M ] H)`, 100], 284 (11), 269
plates, eluting with an 8 : 2 CHCl Èacetone mixture. In decreas-
3
(5), 153 (3), 241 (3), 177 (15), 161 (15), 151 (95), 135 (12), 134
ing R order, in each case, three fractions were collected and
f
(11), 121 (70), 103 (15), 91 (10). Anal. calcd. C
71.82, H 5.67; found: C 71.50, H 5.47%.
H
O : C
identiÐed as h (higher), i (intermediate) and l (lower). After
17 16
4
crystallization from a CH Cl ÈC H
mixture, the yields
2
2
6 12
2@-Hydroxy-3,4,4@,5,6@-pentamethoxychalcone 3. (86%), mp
183È185 ¡C (lit.21 176È178 ¡C). 1H NMR: d \ 3.84 (s, 3H, 4-
OCH ), 3.90 (s, 3H, 6@-OCH ), 3.91 (s, 3H, 4@-OCH ), 3.91 [s,
obtained were as follows. (a) Starting from 1 the following
isomers have been obtained: 5h, 36 mg, 19%; 5i, 97 mg, 51%;
and 5l, 7 mg, 4%. (b) When using 2 as reagent: 6h, 32 mg,
15%; 6i, 92 mg, 45%; and 6l, 8 mg, 4% have been obtained.
(c) When using 3 as reagent: 7h, 45 mg, 18%; 7i, 88 mg, 35%;
and 7l, 5 mg, 2% have been obtained.
3
3
3
6H, 3,5-(OCH ) ]. 13C NMR: d \ 55.4 (6@-OCH ), 55.8 (4@-
3 2
OCH ), 56.1 [3,5-(OCH ) ], 61.0 (4-OCH ).
3 2
3
3
3
2º-Hydroxy-4,4º,5,6,6º-pentamethoxydihydrochalcone 4. Am-
monium formate (3.0 g, 48 mmol) and Pd/C (10%) (0.8 g) were
added to a solution of 3 (1.5 g, 4 mmol) in acetone (60 ml).
The reaction mixture, with magnetic stirring and under nitro-
gen, was reÑuxed for 1 h, Ðltered through a column of celite
and the solvent evaporated to dryness. The obtained residue
was taken up in chloroform and puriÐed by silica gel column
chromatography, using a 9 : 1 mixture of CH Cl Èacetone as
Bis(dimethyl sulfoxide)bis(4-methoxychalconato)ruthenium(II)
5h. Mp 105È108 ¡C. 1H NMR: d \ 3.86 (s, 6H, 2 ] 4-
OCH ). 13C NMR: d \ 55.4 (2 ] 4-OCH ). FAB`-MS: m/z
3
3
(rel. int.) 764 (M`~, 8), 608 (25), 355 (10), 255 (64). Anal. calcd.
for RuC
H 5.03, S 8.01%.
H O S : C 56.60, H 5.01, S 8.40; found: C 56.49,
36 38 8 2
Bis(dimethyl sulfoxide)bis(4-methoxychalconato)ruthenium(II)
5i. Mp 127È130 ¡C. 1H NMR: d \ 3.82 and 3.87 (2s, 2 ] 3H,
2 ] 4-OCH ). 13C NMR: d \ 55.35 and 55.44 (2 ] 4-OCH ).
2
2
eluent. After solvent evaporation the residue was crystallized
from EtOH, giving 4 in 89% yield (1.34 g), mp 118È120 ¡C. 1H
NMR: d \ 3.84 (s, 3H, 4-OCH ), 3.90 (s, 3H, 6@-OCH ), 3.91
3
3
FAB`-MS: m/z (rel. int.) 764 (M`~, 15), 608 (74), 355 (27), 255
3
3
(43). Anal. calcd. for RuC
36 38 8 2
5.50, S 7.96; found: C 58.54, H 5.57, S 8.01%.
H
O S É 0.5C H : C 58.12, H
(s, 3H, 4@-OCH ), 3.92 [s, 6H, 3,5-(OCH ) ]. 13C NMR:
6
12
3
3 2
d \ 55.6 (6@-OCH ), 55.6 (4@-OCH ), 56.1 [3,5-(OCH ) ], 61.0
(4-OCH ). EI-MS: m/z (rel. int.) 376 (M`~, 36), 375 (100), 327
(6), 195 (66), 194 (57), 181 (98), 179 (20), 167 (10), 151 (9), 138
3
3
3 2
Bis(dimethyl sulfoxide)bis(4-methoxychalconato)ruthenium(II)
3
5l. Mp 125È128 ¡C. 1H NMR: d \ 3.82 (s, 6H, 2 ] 4-OCH ).
3
13C NMR: d \ 55.4 (2 ] 4-OCH ). FAB`-MS: m/z (rel. int.)
3
(9), 121 (5), 95 (7). Anal. calcd. C
found: C 63.61, H 6.17%.
H
O : C 63.82, H 6.43;
20 24
7
764 (M`~, 4), 608 (12), 355 (9), 255 (75). Anal. calcd. for
RuC
36 38 8 2
58.34, H 5.77, S 8.26%.
H
O S É 0.5C H : C 58.12, H 5.50, S 7.96; found: C
6
12
Chalconates L1-L3 . (NMR characterisation only) A solution
of the appropriate 2@-hydroxychalcone 1È3 (0.1 mmol) in
Bis(dimethyl sulfoxide)bis(4,6@-dimethoxychalconato)rutheniu-
m(II) 6h. Mp 125È128 ¡C. 1H NMR: d \ 3.846 (s, 6H, 2 ] 6@-
OCH ), 3.851 (s, 6H, 2 ] 4-OCH ). 13C NMR: d \ 55.4
DMSO-d (0.6 ml), was treated with a molar equivalent of
6
potassium tert-butoxide. The reaction mixture was heated at
3
3
40 ¡C, with magnetic stirring and under nitrogen, for 30 min
and then 1H and 13C NMR spectra were recorded. These
values are shown in Tables 1 and 2; however, the proton and
carbon assignments of the methoxyl groups are as follows.
4-Methoxychalconate L1. 1H NMR: d \ 3.77 (s, 3H, 4-
OCH ). 13C NMR: d \ 55.2 (4-OCH ).
(2 ] 4-OCH ), 55.6 (2 ] 6@-OCH ). FAB`-MS: m/z (rel. int.) 827
3
3
[(M ] 3)`, 4], 825 [(M ] H)`, 6], 668 (25), 285 (10), 269 (2).
Anal. calcd. for RuC S É 0.5C H : C 56.87, H 5.59,
S 7.41; found: C 56.87, H 5.55, S 7.50%.
H
O
38 42 10 2 12
6
Bis(dimethyl sulfoxide)bis(4,6@-dimethoxychalconato)rutheniu-
m(II) 6i. Mp 127È130 ¡C. 1H NMR: d \ 3.79 and 3.87 (2s,
3
3
4,6@-Dimethoxychalconate L2. 1H NMR: d \ 3.56 (s, 3H, 6@-
OCH ), 3.77 (s, 3H, 4-OCH ,). 13C NMR: d \ 54.9 (6@-
2 ] 3H, 2 ] 6@-OCH ), 3.82 and 3.85 (2s, 2 ] 3H, 2 ] 4-
3
OCH ). 13C NMR: d \ 55.35 and 55.41 (2 ] 4-OCH ), 55.6
3
3
3
3
3
OCH ), 55.2 (4-OCH ).
and 55.9 (2 ] 6@-OCH ). FAB`-MS: m/z (rel. int.) 827
3
3
3,4,4@,5,6@-Pentamethoxychalconate L3. 1H NMR: d \ 3.53
[(M ] 3)`, 16], 825 [(M ] H)`, 23], 668 (59), 387 (12), 285
(s, 3H, 6@-OCH ), 3.59 (s, 3H, 4-OCH , s), 3.66 (s, 3H, 4@-
(10), 269 (3). Anal. calcd. for RuC
H
O
S É 0.5C H : C
3
3
38 42 10 2 6
12
OCH , s), 3.79 [s, 6H, 3,5-(OCH ) ]. 13C NMR: d \ 54.0 (4@-
56.87, H 5.59, S 7.41; found: C 56.88, H 5.60, S 7.69.%
3
3
3 2
OCH ), 54.6 (6@-OCH ), 55.8 [3,5-(OCH ) ], 60.1 (4-OCH ).
Bis(dimethyl sulfoxide)bis(4,6@-dimethoxychalconato)rutheniu-
m(II) 6l. Mp 96È99 ¡C. 1H NMR: d \ 3.64 (s, 6H, 2 ] 6@-
OCH ), 3.82 (s, 6H, 2 ] 4-OCH ). 13C NMR: d \ 55.4
3
3 2
3
3,4,4@,5,6@-Pentamethoxydihydrochalconate L4. (NMR char-
acterization only) A suspension of 4 (0.1 mmol) in C H -d
6
6
6
3
3
(0.6 ml) was treated with a one molar equivalent of potassium
(2 ] 6@-OCH ), 55.7 (2 ] 4-OCH ). FAB`-MS: m/z (rel. int.)
3
3
334
New J. Chem., 1999, 329È335

View Article Online
825 [(M ] H)`, 4], 668 (8), 387 (4), 285 (59), 269 (1). Anal.
calcd. for RuC S É 0.5C H : C 56.87, H 5.59, S 7.41;
found: C 57.08, H 5.87, S 7.83%.
Acknowledgements
H
O
38 42 10 2 12
6
Thanks are due to the University of Aveiro and the former
INIC (Lisbon) for funding this work. We also thank the
JNICT-French Embassy Protocol for the award of travel
grants; A.M.S.S. also thanks the Calouste Gulbenkian Foun-
dation for the award of two short-period research grants.
Bis(dimethyl
sulfoxide)bis(3,4,4@,5,6@-pentamethoxychalcon-
ato)ruthenium(II) 7h. Mp 119È122 ¡C. 1H NMR: d \ 3.60
(s, 6H, 2 ] 6@-OCH ), 3.79 (s, 6H, 2 ] 4@-OCH ), 3.88 (s, 6H,
3
3
2 ] 4-OCH ), 3.90 [s, 12H, 2 ] 3,5-(OCH ) ]. 13C NMR:
3
3 2
3
d \ 55.2 (2 ] 6@-OCH ), 55.5 (2 ] 4-OCH ), 56.2 [2 ] 3,5-
3
(OCH ) ], 61.0 (2 ] 4-OCH ). FAB`-MS: m/z (rel. int.) 1004
3 2
(M`~, 3), 848 (15), 375 (20). Anal. calcd. for RuC
3
H
O
S :
Notes and references
1 D. N. Dhar, T he Chemistry of Chalcones and Related Compounds,
John Wiley & Sons, New York, 1981.
2 R. J. Grayer, in Methods in Plant Biochemistry, eds. P. M. Dey and
J. B. Harborne, Academic Press, London, 1989, vol. 1, pp. 283È
323.
3 B. A. Bohm, in Methods in Plant Biochemistry, eds. P. M. Dey and
J. B. Harborne, Academic Press, London, 1989, vol. 1, pp. 237È
282.
4 (a) A. Krutosikova and M. Uher, in Natural and Synthetic Sweet
Substances, ed. J. Hudec, Ellis Horwood, New York, 1992, pp. 99È
108; (b) G. E. Dubois, G. A. Crosby, R. A. Stephenson and R. E.
Wingard, Jr., J. Agric. Food Chem., 1977, 25, 763; (c) G. E. Dubois,
G. A. Crosby and R. A. Stephenson, J. Med. Chem., 1981, 24, 408;
(d) A. D. Kinghorn and E. J. Kennelly, J. Chem. Educ., 1995, 72,
676.
5 B. A. Bohm, in T he Flavonoids-Advances in Research Since 1986,
ed. J. B. Harborne, Chapman and Hall, London, 1994, pp. 387È
440.
44 54 16 2
C 52.63, H 5.42, S 6.39; found: C 52.75, H 5.48, S 6.09%.
Bis(dimethyl sulfoxide)bis(3,4,4@,5,6@- pentamethoxychalcon-
ato)ruthenium(II) 7i. Mp 120È123 ¡C. 1H NMR: d \ 3.62 and
3.77 (2s, 2 ] 3H, 2 ] 6@-OCH ), 3.78 and 3.79 (2s, 2 ] 3H, 2
3
] 4@-OCH ), 3.87 and 3.89 (2s, 2 ] 3H, 2 ] 4-OCH ), 3.87
3
3
and 3.90 [2s, 2 ] 6H, 2 ] 3,5-(OCH ) ]. 13C NMR: d \ 55.2
3 2
and 55.3 (2 ] 6@-OCH ), 55.5 (2 ] 4-OCH ), 56.1 and 56.2
3
3
[2 ] 3,5-(OCH ) ], 61.0 (2 ] 4-OCH ). FAB`-MS: m/z (rel.
3 2
3
int.) 1006 [(M ] 2)`~, 2], 1005 [(M ] H)`, 2], 1004 (M`~, 1),
850 (5), 849 (5), 848 (55), 477 (5), 375 (20). Anal. calcd. for
RuC
44 54 16 2
53.54, H 5.67, S 6.30.%
H
O
S É 0.5C H : C 53.96, H 5.78, S 6.13; found: C
6
12
Bis(dimethylsulfoxide)bis(3,4,4@,5,6@-pentamethoxychalconato)-
ruthenium(II) 7l. Mp 138È141 ¡C. 1H NMR: d \ 3.61 (s,
6H, 2 ] 6@-OCH ), 3.80 (s, 6H, 2 ] 4@-OCH ), 3.86 (s, 6H, 2
3
3
] 4-OCH ), 3.88 [s, 12H, 2 ] 3,5-(OCH ) ]. 13C NMR:
3
3 2
d \ 55.4 (2 ] 6@-OCH ), 55.6 (2 ] 4@-OCH ), 56.1 [2 ] 3,5-
6 V. S. Parmar, K. S. Bisht, R. Jain, S. Singh, S. K. Sharma, S.
Gupta, S. Malhotra, O. D. Tyagi, A. Vardhan, H. N. Pati, D. V.
Berghe and A. J. Vlietinck, Indian J. Chem., 1996, 35B, 220.
7 (a) D. A. Lewis, Chem. Brit., February, 1992, 141; (b) S. Esaki, K.
Nishiyama, N. Sugiyama, R. Nakajima, Y. Takao and S. Kamiya,
Biosci. Biotech. Biochem., 1994, 58, 1479.
3
3
(OCH ) ], 61.0 (2 ] 4-OCH ). FAB`-MS: m/z (rel. int.) 1006
3 2
[(M ] 2)`~, 2], 848 (0.1), 375 (74). Anal. calcd. for
3
RuC
H O S É 0.5C H : C 53.96, H 5.78, S 6.13; found: C
44 54 16 2 12
6
53.66, H 5.47, S 5.98.%
8 A. Gadow, E. Joubert and C. F. Hansmann, J. Agric. Food Chem.,
1997, 45, 632.
Bis(dimethyl sulfoxide)bis (3,4,4º,5,6º-pentamethoxydihydro-
chalconato) ruthenium(II) complexes 8.
9 (a) J. Pincemail, C. Deby, K. Drieu, R. Anton and R. Goutier,
Proceedings of the 3rd International Symposium on Flavonoids in
Biology and Medicine, ed. N. P. Das, Singapore University Press,
1990, pp. 161È179; (b) S. V. Jovanovic, S. Steenken, M. Tosic, B.
Marjanovic and M. G. Simic, J. Am. Chem. Soc., 1994, 116, 4846;
(c) W. Bors, W. Heller, C. Michel and K. Stettmaier, in Handbook
of Antioxidants, eds. E. Cadenas and L. Packer, Marcel Dekker,
New York, 1996, pp. 409È466; (d) C. A. Rice-Evans, N. J. Miller
and G. Paganga, Free Radicals Biol. Med., 1996, 20, 933.
10 (a) I. Morel, P. Cillard and J. Cillard, in Flavonoids in Health and
Disease, eds. C. A. Rice-Evans and L. Packer, Marcel Dekker,
New York, 1998, pp. 163È177; (b) S. V. Jovanovic, S. Steenken,
M. G. Simic and Y. Hare, in Flavonoids in Health and Disease, eds.
C. A. Rice-Evans and L. Packer, Marcel Dekker, New York,
1998, pp. 137È161.
11 (a) R. A. Larson, Phytochemistry, 1988, 27, 969; (b) A. Arnoldi, M.
Carughi, G. Farina, L. Merlini and M. G. Parrino, J. Agric. Food
Chem., 1989, 37, 508.
12 M. Palaniandavar and C. Natarajan, Aust. J. Chem., 1980, 33, 737.
13 T. S. Rao, K. L. Reddy and P. Lingaiah, Indian J. Chem., 1988,
27A, 510.
Using 4 and the same experimental procedure described for
the preparation of complexes 7, two fractions have been col-
lected from preparative layer plates. The fraction having the
higher R value is the bis(dimethyl sulfoxide)bis(3,4,4@,5,6@-pen-
f
tamethoxydihydrochalconato) ruthenium(II) complex 8h,
whereas the other fraction is the isomer 8l. After evaporating
the solvents to dryness the residues were crystallized from a
CH Cl ÈC H mixture.
2
2
6 12
Bis(dimethyl sulfoxide)bis (3,4,4@,5,6@-pentamethoxydihydro-
chalconato)ruthenium(II) 8h. (53%), mp 83È85 ¡C. 1H NMR:
d \ 3.72 and 3.75 (2 ] 3H, 2 ] 6@-OCH ), 3.77 and 3.78 (2s,
3
2 ] 3H, 2 ] 4@-OCH ), 3.851 and 3.854 [2s, 2 ] 6H, 2 ] 3,5-
3
(OCH ) ], 3.87 (s, 6H, 2 ] 4-OCH ). 13C NMR: d \ 55.2 and
3 2
3
55.3 (2 ] 4@-OCH ), 55.3 and 55.4 (2 ] 6@- OCH ),56.0 [2 ] 3,
3
3
5-(OCH ) ], 60.8 (2 ] 4-OCH ). FAB`-MS: m/z (rel. int.)
3 2
1008 (M`~, 11), 478 (4), 376 (76). Anal. calcd. for
3
RuC S : C 52.42, H 5.80, S 6.36; found: C 52.87, H
H O
44 58 16 2
5.69, S 5.96.%
14 A. M. S. Silva, J. A. S. Cavaleiro, G. Tarrago and C. Marzin, J.
Heterocycl. Chem., 1994, 31, 97.
15 A. M. S. Silva, W. A. Price and J. A. S. Cavaleiro, T etrahedron
L ett., 1993, 34, 5657.
Bis(dimethyl
sulfoxide)bis(3,4,4@,5,6@-pentamethoxydihydro-
chalconato)ruthenium(II) 8l. (7%), mp 93È96 ¡C. 1H NMR:
d \ 3.61 (s, 6H, 2 ] 6@-OCH ), 3.76 (s, 6H, 2 ] 4@-OCH ), 3.80
3
3
3
3
[s, 12H, 2 ] 3,5-(OCH ) ], 3.81 (s, 6H, 2 ] 4-OCH ). 13C
16 J. D. Fotheringham, G. A. Heath, A. J. Lindsay and T. A. Step-
henson, J. Chem. Res. (S), 1986, 82; J. Chem. Res. (M), 1986, 801.
17 In all the bis(dimethyl sulfoxide)bis(Ñavonato)ruthenium(II) com-
plexes described in ref. 14, the 13C NMR resonances of the methyl
carbon resonances appeared at 41.3È44.2 ppm, which indicates
that in those cases also the DMSO ligands were S-bonded.
18 (a) G. A. Heath, A. J. Lindsay and T. A. Stephenson, J. Chem. Soc.,
Dalton T rans., 1982, 24; (b) M. Iwamoto, E. Alessio and L. G.
Marzilli, Inorg. Chem., 1996, 35, 2384; (c) E. Alessio, M. Calligaris,
M. Iwamoto and L. G. Marzilli, Inorg. Chem., 1996, 35, 2538.
19 A. M. S. Silva, H. R. Tavares, A. I. N. R. A. Barros and J. A. S.
Cavaleiro, Spectrosc. L ett., 1997, 30, 1655.
3 2
NMR: d \ 55.2 (2 ] 4@-OCH ), 55.3 (2 ] 6@-OCH ), 56.0
3
[2 ] 3,5-(OCH ) ], 60.8 (2 ] 4-OCH ). FAB`-MS: m/z (rel.
3 2
int.) 1009 [(M ] H)`, 1], 1008 (M`~, 1), 477 (2). Anal. calcd.
3
for RuC S : C 52.42, H 5.80, S 6.36; found: C 52.67,
H O
44 58 16 2
H 5.99, S 6.16%.
Bis(dimethyl sulfoxide)bis(3,4,4º,5,6º-pentamethoxydihydro-
chalconato)ruthenium(II) 8h. Ammonium formate (38 mg, 0.6
mmol) and Pd/C (10%) (20 mg) were added to a solution of 7i
(100 mg, 0.1 mmol) in acetone (10 ml). The reaction mixture,
with magnetic stirring and under nitrogen, was reÑuxed for 1
h, Ðltered through a column of celite and the solvent evapo-
20 A. G. Doshi and B. J. Ghiya, Curr. Sci., 1986, 55, 502.
21 A. W. Fraser and J. R. Lewis, Phytochemistry, 1974, 13, 1561.
rated to dryness. The residue was crystallized from
a
CH Cl ÈC H mixture, giving 8h in 58% yield (58 mg).
Paper 8/09005J
2
2
6 12
New J. Chem., 1999, 329È335
335