Studies on ruthenium(III) chalconate complexes containing PPh 3/AsPh3

Article abstract of DOI:10.1080/10426500903486706

The reactions of [RuX₃(EPh₃)₃] (X = Cl or Br; E = P or As) with 2′-hydroxychalcones in benzene under reflux led to the formation of [RuX₂(EPh₃)₂(L)] (X = Cl or Br; E = P or As; L = chalcona

Full text of DOI:10.1080/10426500903486706

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Phosphorus, Sulfur, and Silicon and the
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Studies on Ruthenium(III) Chalconate
Complexes Containing PPh /AsPh
3
3
a
a
b
M. Muthukumar , P. Viswanathamurthi & R. Karvembu
a
Department of Chemistry , Periyar University , Salem , India
b
Department of Chemistry , National Institute of Technology ,
Tiruchirappalli , India
Published online: 05 Nov 2010.
To cite this article: M. Muthukumar , P. Viswanathamurthi & R. Karvembu (2010) Studies on
Ruthenium(III) Chalconate Complexes Containing PPh /AsPh , Phosphorus, Sulfur, and Silicon and the
3
3
Related Elements, 185:11, 2201-2211, DOI: 10.1080/10426500903486706
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Phosphorus, Sulfur, and Silicon, 185:2201–2211, 2010
Copyright ꢀ
Taylor & Francis Group, LLC
C
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500903486706
STUDIES ON RUTHENIUM(III) CHALCONATE
COMPLEXES CONTAINING PPh /AsPh
3
3
1
1
2
M. Muthukumar, P. Viswanathamurthi, and R. Karvembu
1
Department of Chemistry, Periyar University, Salem, India
Department of Chemistry, National Institute of Technology, Tiruchirappalli, India
2
ꢀ
The reactions of [RuX3(EPh3)3] (X = Cl or Br; E = P or As) with 2 -hydroxychalcones
in benzene under reflux led to the formation of [RuX2(EPh3)2(L)] (X = Cl or Br; E = P
or As; L = chalconates). The new complexes have been characterized by analytical and
spectroscopic (IR, electronic, and EPR) data. The redox behavior of the complexes has
also been studied. Based on the data, an octahedral structure has been assigned for all the
complexes. The new complexes exhibit efficient catalytic activity for the oxidation of primary
and secondary alcohols into their corresponding aldehydes and ketones in the presence of
N-methylmorpholine-N-oxide (NMO) as co-oxidant and also found efficient catalytic activity
for the transfer hydrogenation of ketones. The antifungal properties of the complexes have
also been examined and compared with standard Bavistin.
Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental
file.
Keywords Antifungal study; catalytic activity; cyclic voltammetry; ruthenium(III) complexes;
spectroscopic characterization
INTRODUCTION
1
The chemistry of ruthenium has been attracting considerable current interest, largely
because of the fascinating photochemical, photophysical, and redox properties exhibited by
complexes of this metal. As all these properties are primarily directed by the coordination
environment around the metal center, complexation of ruthenium by ligands of selected
2
types are of significant importance, and the present study has originated from our interest in
this area. Chalcones are precursors to the flavonoids, natural products that play a significant
role in the disease and parasite resistance of plants. Indeed, there is interest in the use of
chalcone derivatives for pharmaceutical purposes including as antibiotic, antitumor, and
antimalarial agents.3
Received 15 August 2009; accepted 13 November 2009.
The authors express their sincere thanks to Council of Scientific and Industrial Research (CSIR), New Delhi
[
Grant No. 01(2065)/06/EMR-II], for financial support. One of the authors (M.M.) thanks CSIR for the award of
Senior Research Fellowship.
Address correspondence to P. Viswanathamurthi, Department of Chemistry, Periyar University, Salem-636
011, India. E-mail: viswanathamurthi@rediffmail.com
2
201

2
202
M. MUTHUKUMAR ET AL.
Ruthenium complexes have been used as catalysts or catalyst precursors for a va-
riety of purposes including hydrogenation, oxidation, isomerization, polymerization, nu-
4
cleophilic addition to multiple bonds, and carbon–carbon bond formation. The oxidation
of alcohols into their corresponding aldehydes and ketones is of greater importance in
synthetic organic chemistry.5 Though several ruthenium catalytic systems have been
–7
8
9
reported with a wide range of oxidants viz., tert-butyl hydroperoxide, chloramine-T, ben-
10
11
12
13
14
zoquinone, hydrogen peroxide, molecular oxygen, iodosylbenzene, and NaIO4,
N-methylmorpholine-N-oxide (NMO) as an oxidant has received less coverage in the liter-
ature.
More recently, transition metal–catalyzed transfer hydrogenation reactions using iso-
propanol as the hydrogen source have become efficient methods in organic synthesis,
15
as illustrated by several useful applications. Among the different metal-catalyzed re-
actions, ruthenium-based catalytic systems are effective in the transfer hydrogenation of
1
6–23
ketones.
Even though there are a number of reports available on catalytic oxidation
and the transfer hydrogenation of ketones, to the best of our knowledge, there are no re-
ports available for catalytic oxidation of alcohols by ruthenium(III) chalconate complexes
incorporating O,O-donors in the presence of NMO and catalytic transfer hydrogenation of
ketones in the presence of isopropanol and KOH.
In view of the growing interest in the catalytic and biological activities of ruthe-
nium complexes, in this article we report the synthesis of a series of hexacoordinated
ruthenium(III) chalconate complexes containing PPh3/AsPh3. A few of the synthesized
complexes have been effectively used as catalysts in oxidation of alcohols in the presence
of NMO and in transfer hydrogenation of ketones in the presence of isopropanol and KOH.
Further, the new complexes have been screened for their antifungal studies.
RESULTS AND DISCUSSION
Paramagnetic, hexa-coordinated, low-spin ruthenium(III) complexes of the general
formula [RuX2(EPh3)2(L)] (X = Cl or Br; E = P or As; L = chalconates) were synthesized
in good yields from the reaction of [RuX3(EPh3)3] (X = Cl or Br; E = P or As) with
ꢁ
2
-hydroxychalcone ligands in dry benzene in equal molar ratio (Scheme 1). In all these
ꢁ
reactions, it has been observed that the 2 -hydroxychalcones behave as monobasic bidentate
chelating ligands by replacing a triphenylphosphine/arsine and a chloride/bromide ion from
the starting complexes.
All the complexes are stable in air at room temperature, brown in color, non-
hygroscopic, and highly soluble in common organic solvents such as dichloromethane,
acetonitrile, chloroform, and DMSO. The analytical data are in good agreement with the
general molecular formula proposed for all the complexes.
Infrared Spectroscopic Analysis
−
1
The free chalcone ligands showed a strong band in the region 1632–1647 cm due to
−1
υC O. This band has been shifted to a lower wave number 1612–1629 cm in the ruthenium
complexes, indicating the coordination of the ligands to ruthenium through the carbonyl
oxygen atom.24 A strong band observed at 1300–1305 cm in the free chalcone ligands
−1
has been assigned to phenolic υC O stretching. This band has been shifted to higher
−
1
wave number 1306–1317 cm in the spectra of the complexes due to its coordination
25
to the ruthenium ion through the oxygen atom of the phenolic group. This has been

RUTHENIUM(III) CHALCONATE COMPLEXES
2203
HO
[
RuX (EPh ) ]
3 3 3
+
O
C
CH3
CH
CHR
Benzene/
Reflux 6h
EPh3
X
O
Ru
X
O
C
CH3
CH
CHR
EPh3
(X = Cl or Br; E = P orAs; R = 4-(CH
3 6 3 6 6 4 3 2 6 3
)C H4, 4-(OCH )C H4, 4-(Cl)C H or 3, 4-(OCH ) C H )
Scheme 1 Formation of ruthenium(III) chalconate complexes.
−1
further supported by the disappearance of the broad υOH band around 3400–3600 cm
in the complexes, indicating deprotonation of the phenolic proton prior to coordination to
the ruthenium metal. Hence, from the infrared spectroscopic data, it is inferred that both the
carbonyl and phenolic oxygen atoms are involved in the coordination of the chalcones to
ruthenium ion in all the complexes. The absorption due to υC C of the free ligands appeared
−1
as a separate band in their infrared spectra around 1600 cm , but the same could not be
identified in the spectra of the ruthenium complexes because of their possible merging with
26
υC O. In the complexes, the absorption due to the phenyl alkene vibration appeared in
−1
the region 1536–1551 cm , which is slightly lower than that observed in the spectra of
the free ligands.27 In addition, the other characteristic bands due to triphenylphosphine or
−
1
triphenylarsine (around 1440, 1090, and 700 cm ) were also present in the spectra of all
the complexes.28 The observed bands in the regions 460–475 cm in the mononuclear
complexes are tentatively assigned to the υRu Cl vibrations.
−1
29
Electronic Spectroscopic Analysis
The electronic spectra of the ruthenium(III) complexes were recorded in
dichloromethane in the region 900–200 nm. Most of the complexes showed two to three
bands in the region 830–207 nm. The ground state of ruthenium(III) in an octahedral
2
5
environment is T2g, arising from the t configuration, and the first excited doublet levels
2g
2
2
4
1
in the order of increasing energy are A2g and T1g, arising from the t e configuration.
2g
g
2
2
2
2
Hence, two bands corresponding to T2g → A2g and T2g → T1g are possible. The
absorption bands around 830–802 nm and 442–401 nm are assigned to d–d and charge

2
204
M. MUTHUKUMAR ET AL.
transfer (LMCT) transitions respectively. In most ruthenium(III) complexes, charge
transfer bands of the type Lπy → T2g are prominent in the low-energy region, which
30
obscures the weaker bands due to d–d transitions. It is therefore difficult to assign
conclusively the bands of the ruthenium(III) complexes that appear in the visible region.
However, the extinction coefficients for the bands 830–802 nm are found to be low
compared to that of the charge transfer bands. Hence the bands around 830–802 nm have
2
2
been assigned to T2g → A2g, which is in conformity with the assignment made for similar
octahedral ruthenium(III) complexes.3
1,32
The absorptions in the ultraviolet region below
4
00 nm are very similar and are attributable to the transitions within the ligand orbital
∗ ∗
(
π–π , n–π ) that are taking place in the chalcone ligands. The pattern of the electronic
spectra of all the complexes indicated the presence of an octahedral environment around
the ruthenium(III) ion.
Cyclic Voltammetry
The electrochemical properties of some of the complexes have been examined cyclic
voltammetrically under N2 atmosphere at glassy carbon working electrode in acetonitrile
solution (0.05 M: NBu4ClO4), and the redox potentials are expressed with reference to
−3
Ag/AgCl. All the complexes (1 × 10 M) are electroactive with respect to the metal
centers and exhibited two redox processes in the potential range +1.5 V to −1.5 V. The
complexes display a reversible oxidative (RuIV/RuIII) and reversible reductive response
−1
(
RuIII/RuII) at the scan rate of 100 mVs . (See Table S1 in the Supplemental Materials,
available online.)
EPR Spectroscopic Analysis
The solid state EPR spectra of all the ruthenium(III) chalconate complexes (a rep-
resentative spectrum is given in Figure 1) were recorded in X-band frequencies at room
temperature. All the new complexes showed a single isotropic line with “g” values in the
range 2.30–2.52, indicating a high symmetry around the ruthenium ion. Such isotropic lines
are due either to the results of intermolecular spin exchange, which can broaden the lines,
or to occupancy of the unpaired electron in a degenerate orbital.
The nature and pattern of the EPR spectra suggest an almost perfect octahedral
33,34
environment around the ruthenium ion in the complexes,
interactions with any other nuclei present in the complexes.
and there are no hyperfine
Based on the above analytical and spectroscopic data, an octahedral structure (Scheme
) has been suppositionally proposed for all the ruthenium(III) chalconate complexes.
1
Catalytic Oxidation
Catalytic oxidation of primary alcohols and secondary alcohols by the synthesized
ruthenium(III) chalconate complexes was carried out in CH2Cl2 in the presence of NMO,
and the byproduct water was removed by using molecular sieves. All the complexes oxidize
primary alcohols to the corresponding aldehydes and secondary alcohols to ketones with
high yields. The aldehydes or ketones formed after 3 h of refluxing were determined by
GC, and there was no detectable oxidation in the absence of ruthenium complex.
The oxidation of benzylalcohol to benzaldehyde resulted in 93–99% yield, and cy-
clohexanol to cyclohexanone resulted in 53–82% yield. The relatively higher product yield

RUTHENIUM(III) CHALCONATE COMPLEXES
2205
1
Figure 1 EPR spectrum of [RuCl2(AsPh3)2(L )].
obtained for the oxidation of benzylalcohol as compared to cyclohexanol is due to the fact
that the α-CH unit of benzylalcohol is more acidic than cyclohexanol.35 It has been ob-
served that the triphenylarsine ruthenium(III) chalconate complexes possess slight changes
in catalytic activity compared to triphenylphosphine complexes. The conversion of primary
and secondary alcohols to corresponding aldehydes and ketones increases with increase in
reaction time up to 3 h (Table S2, Supplemental Materials).
The results of the present investigations suggest that the complexes are able to react
36
efficiently with NMO to yield a high-valent ruthenium-oxo species capable of oxygen
atom transfer to alcohols. This was further supported by spectroscopic changes that occur
by addition of NMO to dichloromethane solution of the ruthenium(III) complexes. The
V
appearance of a peak at 390 nm is attributed to the formation of Ru = O species, which is
37,38
in conformity with other oxo ruthenium(V) complexes.
Further support in favor of the
formation of such species was identified from the IR spectrum of the solid mass (obtained
−1
by evaporation of the resultant solution to dryness), which showed a band at 860 cm ,
V
36,38
characteristic of Ru = O species
(Scheme 2).
Catalytic Transfer Hydrogenation
The catalytic transfer hydrogenation of acetophenone in the presence of ruthenium
chalconate complexes has been studied in isopropanol–KOH medium using a molar ratio
of 1:2.5:300 for the catalyst, KOH, and the ketone in 10 mL of isopropanol.

2
206
M. MUTHUKUMAR ET AL.
O
O
N
III
(
ligand)Ru (PPh )
H O + 2PPh
+
3 2
2
3
H C
3
O
O
OH
(
ligand)RuV
O
+ 2PPh3
N
CH3
Scheme 2 Proposed catalytic cycle for the oxidation of alcohols by the ruthenium(III) chalconate complexes.
The catalyst performed efficiently for both aliphatic and aromatic ketones with
high conversion. Cyclohexanone was converted into cyclohexanol in 78–99% yield (Table
S3, Supplemental Materials). Acetophenone was converted into corresponding alcohol in
28–95% yield. Similarly, benzophenone underwent transfer hydrogenation to afford the
corresponding alcohol in 84–99% yield. The product formation in the absence of base was
very low. The role of KOH is to generate the catalyst from the chloro precursor, and the
reaction mediates through the hydride species. The base facilitated the formation of the
ruthenium alkoxide by abstracting the proton of the alcohol and, subsequently, the alkoxide
underwent β-elimination to give ruthenium hydride, which is the active species in this
39
reaction.
Antifungal Activity
The in vitro antifungal screening against Aspergillus niger and Mucor Sp. for the
ligands and some of their ruthenium(III) chalconate complexes has been carried out by the
disc diffusion method40 (see the Supplemental Materials for complete details). The results
showed that the ruthenium complexes are more toxic than their parent ligands against the
same microorganisms under identical experimental conditions (Table S4, Supplemental
Materials).
MATERIALS AND METHODS
All the reagents used were chemically pure and AR grade. The solvents were purified
41
and dried according to standard procedures. RuCl3·3H2O was purchased from Loba
Chemie Pvt. Ltd., and was used without further purification. The microanalyses of carbon,
hydrogen, and nitrogen were recorded by a Carlo-Erba 1108 model analyzer at Central Drug
Research Institute (CDRI), Lucknow, India. Infrared spectra of the ligands and complexes
−1
were recorded in KBr pellets with a Nicolet FT-IR spectrophotometer in the 400–4000 cm
range. Electronic spectra of the complexes have been recorded in CH2Cl2 using a Shimadzu
UV-visible 1650 PC spectrophotometer in the 200–900 nm range. Electron paramagnetic
resonance spectra (EPR) of the powdered samples were recorded with a JEOL JES-FA200
instrument at X-band frequencies in room temperature using 2,2-diphenyl-1-picrylhydrazyl
radical (DPPH) as internal standard at Pondicherry University, Pondicherry, India. Cyclic
voltammetric measurements were carried out with a BAS CV-27 electrochemical analyzer

RUTHENIUM(III) CHALCONATE COMPLEXES
2207
in acetonitrile using [NBu4]ClO4 (TBAP) as the supporting electrolyte under nitrogen
atmosphere. A three-electrode cell was employed with a glassy carbon working electrode,
a platinum wire counter electrode, and an Ag/AgCl reference electrode. Melting points
were recorded on a Technico micro heating table and are uncorrected. The catalytic yields
were determined using ACME 6000 series GC-FID with a DP-5 column of 30 m length,
4
2
0
[
.53 mm diameter, and 5.00 µm film thickness. The starting complexes [RuCl3(PPh3)3],
RuCl3(AsPh3)3],43 and [RuBr3(AsPh3)3] were prepared according to the methods in the
44
literature.
ꢀ
Synthesis of 2 -Hydroxychalcone Ligands
ꢁ
2
-Hydroxychalcone ligands were prepared by condensing 4-substituted benzalde-
hyde (0.6007–0.8309 g, 5 mmol) with 2-hydroxy-5-methylacetophenone (0.7509 g, 5
mmol) in the presence of alcoholic sodium hydroxide solution (50 mL, 20%). After 24
h of stirring, the product was precipitated by the addition of concentrated hydrochloric
acid, followed by filtration, and then the product was recrystallized from ethanol.
1
−1
2
L : FT-IR (KBr, cm ): ν(C O) 1637, ν(C O) 1302, ν(C C) 1569. L : FT-IR (KBr,
−1
3
−1
cm ): ν(C O) 1635, ν(C O) 1300, ν(C C) 1555. L : FT-IR (KBr, cm ): ν(C O)
647, ν(C O) 1302, ν(C C) 1571. L : FT-IR (KBr, cm ): ν(C O) 1632, ν(C O) 1305,
4
−1
1
ν(C C) 1547.
Synthesis of New Ruthenium(III) Chalconate Complexes
All reactions were carried out under anhydrous conditions and were prepared by the
following common procedure. To a solution of [RuX3(EPh3)3] (X = Cl or Br; E = P or
ꢁ
As) (0.1 g) in benzene (20 mL), the appropriate 2 -hydroxychalcone (0.02–0.03 g) was
added in 1:1 molar ratio. The mixture was heated under reflux for 6 h. The reaction mixture
gradually changed to deep color, and the solvent was removed under reduced pressure. The
◦
product was separated by the addition of a small amount of petroleum ether (60–80 C) and
recrystallized from a CH2Cl2/petroleum ether mixture. The compounds were dried under
vacuum, and the purity of the complexes was checked by TLC.
1
◦
[
RuCl2(PPh3)2(L )]. Brown, dp 202 C, yield 61%, Anal. Calcd. for
C53H45O2P2Cl2Ru: C, 67.16; H, 4.78. Found: C, 67.21; H, 4.72%. FT-IR (KBr,
−
1
cm ): ν(C O) 1619; ν(C O) 1315; ν(C C) 1536; (PPh3/AsPh3) 1435, 1091, 694. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 830(1321), 402(15280), 358(24160).
2
◦
[RuCl2(PPh3)2(L )]. Brown, dp 175 C, yield 58%, Anal. Calcd. for
C53H45O3P2Cl2Ru: C, 66.04; H, 4.70. Found: C, 66.10; H, 4.70%. FT-IR (KBr,
−
1
cm ): ν(C O) 1623; ν(C O) 1310; ν(C C) 1536; (PPh3/AsPh3) 1434, 1091, 694. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 380(22360), 231(31143).
3
◦
[RuCl2(PPh3)2(L )]. Brown, dp 172 C, yield 64%, Anal. Calcd. for
C52H42O2P2Cl3Ru: C, 64.50; H, 4.37. Found: C, 64.46; H, 4.35%. FT-IR (KBr,
−
1
cm ): ν(C O) 1620; ν(C O) 1312; ν(C C) 1536; (PPh3/AsPh3) 1435, 1091, 694. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 802(1442), 350(25190), 232(31160).
4
◦
[RuCl2(PPh3)2(L )]. Brown, dp 178 C, yield 71%, Anal. Calcd. for
C54H47O4P2Cl2Ru: C, 65.26; H, 4.76. Found: C, 65.32; H, 4.72%. FT-IR (KBr,
−
1
cm ): ν(C O) 1623; ν(C O) 1311; ν(C C) 1541; (PPh3/AsPh3) 1438, 1093, 695. UV
(
3
−1 −1
CH2Cl2, nm (ε, dm mol cm )): 401(15137), 232(31160), 209(27694).

2
208
M. MUTHUKUMAR ET AL.
1
◦
[
RuCl2(AsPh3)2(L )]. Brown, dp 160 C, yield 59%, Anal. Calcd. for
C53H45O2As2Cl2Ru: C, 61.46; H, 4.38. Found: C, 61.42; H, 4.41%. FT-IR (KBr,
−
1
cm ): ν(C O) 1627; ν(C O) 1317; ν(C C) 1542; (PPh3/AsPh3) 1436, 1077, 693. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 817(1367), 236(32175).
2
◦
[RuCl2(AsPh3)2(L )]. Brown, dp 149 C, yield 65%, Anal. Calcd. for
C53H45O3As2Cl2Ru: C, 60.52; H, 4.30. Found: C, 60.48; H, 4.28%. FT-IR (KBr,
−
1
cm ): ν(C O) 1624; ν(C O) 1315; ν(C C) 1551; (PPh3/AsPh3) 1435, 1078, 692. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 364(23532), 233(31530), 223(28478).
3
◦
[RuCl2(AsPh3)2(L )]. Brown, dp 135 C, yield 72%, Anal. Calcd. for
C52H42O2As2Cl3Ru: C, 59.13; H, 4.00. Found: C, 59.09; H, 3.97%. FT-IR (KBr,
−
1
cm ): ν(C O) 1625; ν(C O) 1312; ν(C C) 1542; (PPh3/AsPh3) 1435, 1076, 694. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 383(22128), 223(28354).
4
◦
[RuCl2(AsPh3)2(L )]. Brown, dp 153 C, yield 64%, Anal. Calcd. for
C54H47O4As2Cl2Ru: C, 59.95; H, 4.38. Found: C, 60.01; H, 4.39%. FT-IR (KBr,
−
1
cm ): ν(C O) 1622; ν(C O) 1313; ν(C C) 1548; (PPh3/AsPh3) 1435, 1076, 693. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 393(25495), 233(31530).
1
◦
[RuBr2(AsPh3)2(L )]. Brown, dp 125 C, yield 59%, Anal. Calcd. for
C53H45O2As2Br2Ru: C, 56.60; H, 4.00. Found: C, 56.54; H, 4.06%. FT-IR (KBr,
−
1
cm ): ν(C O) 1625; ν(C O) 1306; ν(C C) 1543; (PPh3/AsPh3) 1435, 1080, 691. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 401(15137), 235(26970), 207(25682).
2
◦
[RuBr2(AsPh3)2(L )]. Brown, dp 145 C, yield 55%, Anal. Calcd. for
C53H45O3As2Br2Ru: C, 55.80; H, 3.97. Found: C, 55.78; H, 3.98%. FT-IR (KBr,
−
1
cm ): ν(C O) 1628; ν(C O) 1311; ν(C C) 1539; (PPh3/AsPh3) 1435, 1079, 691. UV
3
−1 −1
(
CH2Cl2, nm (ε, dm mol cm )): 440(16342), 234(35890), 221(27963).
3
◦
[
RuBr2(AsPh3)2(L )]. Brown, dp 135 C, yield 63%, Anal. Calcd. for C52H42O2Cl
−1
As2Br2Ru: C, 54.54; H, 3.69. Found: C, 54.56; H, 3.71%. FT-IR (KBr, cm ): ν(C O)
1
629; ν(C O) 1306; ν(C C) 1545; (PPh3/AsPh3) 1435, 1079, 691. UV (CH2Cl2, nm (ε,
3
−1
−1
dm mol cm )): 439(15598), 237(32398).
4
◦
[
RuBr2(AsPh3)2(L )]. Brown, dp 138 C, yield 70%, Anal. Calcd. for C54H47O4
−1
As2Br2Ru: C, 55.40; H, 4.05. Found: C, 55.36; H, 4.07%. FT-IR (KBr, cm ): ν(C O)
1
612; ν(C O) 1312; ν(C C) 1537; (PPh3/AsPh3) 1435, 1080, 691. UV (CH2Cl2, nm (ε,
3
−1
−1
dm mol cm )): 442(17580), 232(31160).
Catalytic Oxidation
Catalytic oxidation of primary alcohols to corresponding aldehydes and secondary
alcohols to ketones by ruthenium(III) chalconate complexes was studied in the presence
of NMO as co-oxidant. A typical reaction using the complex as a catalyst and primary or
secondary alcohol as substrates at 1:100 molar ratio was described as follows. A solution of
ruthenium complex (0.01 mmol) in CH2Cl2 (20 mL) was added to the mixture containing
substrate (1 mmol), NMO (3 mmol), and molecular sieves. The reaction mixture was
refluxed for 3 h, and the solvent was then evaporated from the mother liquor under reduced
◦
pressure. The solid residue was then extracted with petroleum ether (60–80 C, 20 mL)
and was analyzed by GC. The oxidation products were identified by GC co-injection with
authentic samples.

RUTHENIUM(III) CHALCONATE COMPLEXES
2209
Catalytic Transfer Hydrogenation of Ketones
The catalytic transfer hydrogenation reactions were also studied using ruthenium(III)
chalconate complexes as a catalyst, ketone as substrate, and KOH as promoter in 1:300:2.5
molar ratios. The procedure was described as follows. A mixture containing ketone (3.75
mmol), the ruthenium complex (0.0125 mmol), and KOH (0.03 mmol) in i-prOH (10 mL)
was reacted under reflux in a water bath for 2 h. After completion of the reaction, the
catalyst was removed from the reaction mixture by the addition of diethyl ether followed
by filtration and subsequent neutralization with 1 M HCl. The ether layer was filtered
through a short path of silica gel by column chromatography. The filtrate was subjected to
GC analysis, and the hydrogenated product was identified and determined with authentic
samples.
CONCLUSIONS
Several new ruthenium(III) chalconate complexes were synthesized using chalcone
formed from derivatives of benzaldehyde and 2-hydroxy-5-methylacetophenone. The new
complexes have been characterized by analytical and spectroscopic (IR, electronic, and
EPR) data. An octahedral structure has been tentatively proposed for all the complexes.
The complexes showed efficient catalytic activity for the oxidation of both primary and
secondary alcohols with excellent yields in the presence of N-methylmorpholine-N-oxide,
and also for transfer hydrogenation of aliphatic and aromatic ketones with high conversions
in the presence of isopropanol and KOH as promoter. The complexes exhibited considerable
amounts of antifungal activity at the time of screening.
REFERENCES
1. (a) M. Turki and C. Daniel, Coord. Chem. Rev., 216, 31 (2001); (b) V. Balzani, A. Juris, Coord.
Chem. Rev., 211, 97 (2001); (c) G. Simonneaux and P. Le Maux, Coord. Chem. Rev., 228, 43
(2002); (d) H. Yersin and C. Kratzer, Coord. Chem. Rev., 229, 75 (2002); (e) M. J. Clarke,
Coord. Chem. Rev., 236, 209 (2003); (f) I. Ando, Coord. Chem. Rev., 248, 185 (2004); (g) R. F.
Winter and S. Zali, Coord. Chem. Rev., 248, 1565 (2004); (h) M. K. Nazeeruddin, C. Klein, P.
Liska, and M. Gratzel, Coord. Chem. Rev., 249, 1460 (2005).
2
. (a) F. Basuli, S. M. Peng, and S. Bhattacharya, Inorg. Chem., 36, 5645 (1997); (b) A. K. Das, A.
Rueda, L. R. Falvello, S. M. Peng, and S. Bhattacharya, Inorg. Chem., 38, 4365 (1999); (c) F.
Basuli, S. M. Peng, and S. Bhattacharya, Inorg. Chem., 39, 1120 (2000); (d) K. Majumder, R.
J. Butcher, and S. Bhattacharya, Inorg. Chem., 41, 4605 (2002); (e) P. K. Sinha, L. R. Falvello,
and S. Bhattacharya, Ind. J. Chem., 43A, 1846 (2004); (f) P. Gupta, S. Dutta, F. Basuli, S. M.
Peng, G. H. Lee, and S. Bhattacharya, Inorg. Chem., 45, 460 (2006); (g) A. M. S. Silva, J. A. S.
Cavaleiro, G. Tarragob, and C. Marzinb, New. J. Chem., 329 (1999); (h) L. Mishra, R. Sinha, H.
Itokawa, K. F. Bastow, Y. Tachibana, Y. Nakanishi, N. Kilgorec, and K. H. Leeb, Bioorg. Med.
Chem., 9, 1667 (2001).
3
4
. D. N. Dhar, The Chemistry of Chalcones and Related Compounds (Wiley, New York, 1981).
. R. Drozdzak, B. Allaert, N. Ledoux, I. Dragutan, V. Dragutan, and F. Verpoort, Coord. Chem.
Rev., 249, 3055 (2005).
5. S. V. Ley, J. Norman, W. P. Griffith, and S. P. Marsden, Synthesis, 639 (1994).
6. S. Kanemote, S. Matsubara, K. Takai, and K. Oshima, Tetrahedron Lett., 24, 2185 (1983).
7. A. Hanyu, E. Takezwa, S. Sakaguchi, and Y. Ishii, Tetrahedron Lett., 39, 5557 (1998).
8. D. Chatterjee, A. Mitra, and S. Mukherjee, J. Mol. Catal. A: Chem., 165, 295 (2001).
9. K. B. Sharpless, K. Akashi, and K. Oshima, Tetrahedron Lett., 17, 2503 (1976).

2
210
M. MUTHUKUMAR ET AL.
1
1
0. J. E. Backvall, R. L. Chowdhury, and U. Karlsson, J. Chem. Soc., Chem. Commun., 473 (1991).
1. S. Campestrini, M. Carraro, U. Tonellato, M. Pagliaro, and R. Ciriminna, Tetrahedron Lett., 45,
283 (2004).
7
1
1
1
1
2. C. Bilgrien, S. Davis, and R. S. Drago, J. Am. Chem. Soc., 109, 3786 (1987).
3. P. Muller and J. Godoy, Tetrahedron Lett., 22, 2361 (1981).
4. W. S. Trahanosky, Oxidation of Organic Chemistry, Part B (Academic Press, New York, 1973).
5. (a) E. P. Kelson and P. P. Phengsy, J. Chem. Soc., Dalton Trans., 129 (2000); (b) R. K. Rath,
M. Nethaji, and A. R. J. Chakravarty, Organomet. Chem., 633, 79 (2001); (c) J. E. Backvall, J.
Organomet. Chem., 652, 105 (2002); (d) J. Q. Yu, H. C. Wu, C. Ramarao, J. B. Spencer, and S.
V. Ley, Chem. Commun., 678 (2003); (e) J. Hannedouche, G. J. Clarkson, and M. J. Wills, J.
Am. Chem. Soc., 126, 986 (2004).
1
6. (a) R. Noyori and S. Hashiguchi, Acc. Chem. Res., 30, 97 (1997); (b) M. J. Palmer, M. Will,
Tetrahedron: Asymmetry, 10, 2045 (1999); (c) K. Okano, K. Murata, and T. Ikariya, Tetrahedron
Lett., 41, 9277 (2000); (d) J. S. Chen, Y. Li, Z. Dong, B. Li, and J. Gao, Tetrahedron Lett., 45,
8
415 (2004).
7. M. Poyatos, J. A. Mata, E. Falomir, R. H. Crabtree, and E. Peris, Organometallics, 22, 1110
2003).
1
(
1
1
2
2
8. A. A. Danopoulus, S. Winston, and W. B. Motherwell, Chem. Commun., 1376 (2002).
9. J. Louie, C. W. Bielawski, and R. H. Grubbs, J. Am. Chem. Soc., 123, 11312 (2001).
0. R. Noyori and T. Okhuma, Angew. Chem., Int. Ed., 40, 40 (2001).
1. (a) T. Ohkuma, H. Ooka, S. Harshiguchi, T. Ikariya, and R. Noyori, J. Am. Chem. Soc., 117,2675
(
1995); (b) T. Okhuma, H. Takeno, and R. Noyori, Adv. Synth. Catal., 343, 369 (2001).
2. (a) M. Albrecht, B. M. Kocks, A. L. Spek, and G. V. Koten, J. Organomet. Chem., 624, 271
2001); (b) P. Dani, T. Karlen, R. A. Gossage, S. Gladiali, and G. V. Koten, Angew. Chem., Int.
2
(
Ed., 112, 759 (2000).
2
3. (a) T. Ohkuma, M. Koizumi, H. Doucet, T. Pham, M. Kozawa, K. Murata, E. Katayama, T.
Yokozawa, T. Ikariya, and R. Noyori, J. Am. Chem. Soc., 120, 13529 (1998); (b) T. Ohkuma,
D. Ishii, H. Takeno, and R. Noyori, J. Am. Chem. Soc., 122, 6510 (2000); (c) T. Ohkuma, M.
Koizumi, H. Ikehira, T. Yokozawa, and R. Noyori, Org. Lett., 2, 659 (2000).
4. M. Muthukumar and P. Viswanathamurthi, Spectrochim. Acta, 70A, 1222 (2008).
5. M. Sivagamasundari and R. Ramesh, Spectrochim. Acta, 67A, 256 (2007).
6. N. Fuson, M. L. Josien, and E. M. Shelton, J. Am. Chem. Soc., 76, 2526 (1954).
7. M. V. Kaveri, R. Prabhakaran, R. Karvembu, and K. Natarajan, Spectrochim. Acta, 61A, 2915
2
2
2
2
(2005).
2
8. J. R. Dyer, Application of Absorption Spectroscopy of Organic Compounds (Prentice-Hall,
Englewood Cliffs, NJ, 1978).
2
3
3
3
3
3
3
9. M. S. El-Shahawi and A. F. Shoair, Spectrochim. Acta, 60A, 121 (2004).
0. N. Dharmaraj, P. Viswanathamurthi, and K. Natarajan, Trans. Met. Chem., 26, 105 (2001).
1. K. Natarajan and U. Agarwala, Bull. Chem. Soc. Jpn., 49, 2877 (1976).
2. A. B. P. Lever, Inorganic Electronic Spectroscopy, 2nd ed. (Elsevier, New York, 1984).
3. M. M. T. Khan, D. Srinivas, R. I. Khureshy, and N. H. Khan, Inorg. Chem., 29, 2320 (1990).
4. O. K. Medhi and U. Agarwala, Inorg. Chem., 19, 1381 (1980).
5. K. P. Balasubramanian, R. Karvembu, R. Prabhakaran, V. Chinnusamy, and K. Natarajan, Spec-
trochim. Acta, 65A, 678 (2006).
36. W. H. Leung and C. M. Che, Inorg. Chem., 28, 4619 (1989).
37. A. M. El-Hendawy, A. H. Alkubaisi, A. E. Kourashy, and M. M. Shanab, Polyhedron, 12, 2343
(1993).
38. M. M. T. Khan, Ch. Sreelatha, S. A. Mirza, G. Ramachandraiah, and S. H. R. Abdi, Inorg. Chim.
Acta, 154, 103 (1988).
39. (a) K. J. Haack, S. Hashiguchi, A. Fujji, J. Takehera, T. Ikariya, R. Noyori, Angew. Chem., Int.
Ed., 36, 285 (1997); (b) A. Aranyos, G. Csjernyik, K. J. Szabo, and J. Backvall, Chem. Commun.,
3
51 (1999).

RUTHENIUM(III) CHALCONATE COMPLEXES
2211
40. C. H. Colins and P. M. Lyne, Microbial Methods (University Park Press, Baltimore, MD, 1970).
41. A. I. Vogel, Text Book of Practical Organic Chemistry, 5th ed. (Longman, London, 1989).
42. J. Chatt, G. J. Leigh, D. M. P. Mingos, and R. J. Paske, J. Chem. Soc. A, 2636 (1968).
43. R. K. Poddar, I. P. Khullar, and U. Agarwala, J. Inorg. Nucl. Chem. Lett., 10, 221 (1974).
44. K. Natarajan, R. K. Poddar, and U. Agarwala, J. Inorg. Nucl. Chem., 39, 431 (1977).