Synthesis, characterization, Catalytic and antibacterial activity of two series of dinuclear ruthenium sulphoxide complexes using 5,5'- methylenebis(pyridine) as bis-chelating bridging ligand

Article abstract of DOI:10.1002/jccs.201100049

The reaction of a new heterocyclic bidentate N containing spacer, (ligand) 5,5'-methylenebis(pyridine) with ruthenium sulphoxide precursors resulted, dinuclear complexes. We herein report three formulations; [{cis,fac-RuCl ₂(so)₃}₂(μ-mbp)].3so; [{trans,mer-RuCl ₂(so)₃}₂(μ-mbp)].3so and [{trans-RuCl ₄(so)}₂(μ-mbp)]^2-[X]₂ ⁺; where so = dimethyl-sulfoxide/tetramethylenesulfoxide; mbp = 5,5'-methylenebis(pyridine) and [X]⁺ = [(dmso)₂H] ⁺, Na⁺ or [(tmso)H]⁺. These complexes were characterized on the basis of elemental analyses, molar conductance measurement, magnetic susceptibility, FT-IR, ¹H-NMR, ¹³C{1H}-NMR, electronic spectroscopy and FAB-Mass spectrometry. Catalytic activity of these complexes has been investigated in hydrolysis of benzonitrile. All the complexes exhibit good antibacterial activity against gram-negative bacteria Escherichia coli in comparison to Chloramphenicol.

Full text of DOI:10.1002/jccs.201100049

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Article
Synthesis, Characterization, Catalytic and Antibacterial Activity of Two Series of
Dinuclear Ruthenium Sulphoxide Complexes Using 5,5¢-Methylenebis(pyridine) as
Bis-chelating Bridging Ligand
Satyendra N. Shukla,a* Pratiksha Gaur,a Mamta Prasad,a Mahender Prasad,b Ripul Mehrotraa
and Sheela Mathewsa
aCoordination Chemistry Research Lab, Department of Chemistry, Govt. Model Science College,
Jabalpur (MP) 482 001, India
bDMSRDE, GT Road, Kanpur (UP), India
(Received Jan. 20, 2011; Accepted May 27, 2011; Published Online Jun. 7, 2011; DOI: 10.1002/jccs.201100049)
The reaction of a new heterocyclic bidentate N containing spacer, (ligand) 5,5¢-methylenebis(pyridine)
with ruthenium sulphoxide precursors resulted, dinuclear complexes. We herein report three formula-
tions; [{cis,fac-RuCl2(so)3}2(µ-mbp)].3so; [{trans,mer-RuCl2(so)3}2(µ-mbp)].3so and [{trans-
RuCl4(so)}2(µ-mbp)]2-[X]2 ; where so = dimethyl-sulfoxide/tetramethylenesulfoxide; mbp = 5,5¢-meth-
+
ylenebis(pyridine) and [X]+ = [(dmso)2H]+, Na+ or [(tmso)H]+. These complexes were characterized on
1
the basis of elemental analyses, molar conductance measurement, magnetic susceptibility, FT-IR, H-
NMR, 13C{1H}-NMR, electronic spectroscopy and FAB-Mass spectrometry. Catalytic activity of these
complexes has been investigated in hydrolysis of benzonitrile. All the complexes exhibit good antibacte-
rial activity against gram-negative bacteria Escherichia coli in comparison to Chloramphenicol.
Keywords: Ruthenium; Dimethylsulfoxide; Tetramethylenesulfoxide; 5,5¢-Methylenebis(pyridine).
INTRODUCTION
The ruthenium complexes have been extensively
new look to synthesized molecule.11 Ruthenium complexes
have generated interest in the synthesis of new compounds
in view of their lack of side effects and selective antimeta-
static property.12-16
studied in terms of its coordination and organometallic
chemistry due to stability, catalytic and biological applica-
tion. In medicinal field, there are two ruthenium based inor-
ganic compound, NAMI-A, [ImH]+[trans-Ru(Im)(dmso)-
Cl4]-1-3 and KP1019, [trans-tetracholorobis(Indazole)ru-
thenate(III)], have been introduce as anticancer agent and
have completed phase-I clinical trials.4-6 N-N¢ donor lig-
ands have been synthesized for their catalytic properties
with some Ru(II)/(III)complexes.7 Despite these great
pharmacological profile ruthenium complexes are also re-
cently studied for antibacterial and antifungal properties
and screened for a wide range of plant and animal patho-
gens.8,9 These complexes are well suited to medicinal uses
due to their rate of ligand exchange, range of accessible ox-
idation states and ability of ruthenium to mimic iron in
binding to certain biological molecules.10
The ligand, 5,5¢-methylenebis(pyridine) having N-
donor site at opposite ends, has an ability to link two metal
center at a time at a definite space which may introduce
good activity in the resulting complexes probably due to
greater metal content and more stereo specificity. There-
fore, the aim of present work is to explore the reaction of
this novel and biologically active spacer with ruthenium
sulphoxide precursor, which may result in to the formation
of dinuclear complexes with rich and unique reactivity.
RESULTS AND DISCUSSION
Characterization of ligand
The analytical data for the newly synthesized ligand
is in good agreement with the proposed empirical formula.
In FAB-mass spectrum of ligand shows a [M+H]+ pseudo
molecular ion peak at m/z = 171, confirming the molecular
weight of the ligand.
The 2-aminopyridine functionally, closely related to
biological systems, which, shows good biological activity,
is able to form self-complementary intermolecular interac-
tion. These compounds, bearing two 2-aminopyridyl moi-
eties which were separated by linkers of different shape,
length and devoid of any other functionality that might give
The ligand was characterized on the basis of FT-IR,
1H-NMR, 13C{1H}-NMR spectra. In FT-IR spectrum of
ligand, three sharp bands appeared at 1608, 1560 and 1508
* Corresponding author. E-mail: ccrl_2004@rediffmail.com; sns1963_1@rediffmail.com
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cm-1 were assigned for the cyclic C=C and C=N and the
band observed at 2930 cm-1 and 2840 cm-1 were assigned
1
for n(CH2) stretching vibrations. H-NMR spectrum of
and 7, three bands were observed. The first two bands ap-
peared between 468-374 nm were ascribed to charge trans-
fer transition from chloride to Ru(III), a typical identifica-
tion for RuCl4 unit.22 In complex 3 and 7 a weak absorption
-
ligand exhibit multiplet between d 7.60-8.12 ppm was as-
signed for the six heteroaromatic protons. A sharp singlet
observed at d 2.78 ppm was assigned for the two methyl-
enic protons. In 13C{1H}-NMR spectrum of ligand, a signal
for the methylenic carbon was observed at d 38.9 ppm. Sig-
nals for heteroaromatic carbon were observed between d
136.8-148.3 ppm.
Thus on the basis of FT-IR, 1H-NMR, 13C{1H}-NMR
spectral studies and elemental data the most probable struc-
ture of the ligand is suggested in Fig. 1.
band at about 300 nm, probably due to the presence of
protonated sulphoxide cation.18-21
Infrared spectra
Three sharp bands at 1608, 1560 and 1508 cm-1 were
attributed for cyclic (C=C) and (C=N), found shifted to-
wards higher frequency region by ~30-40 cm-1, in all the
complexes; indicating the coordination of ligand to metal
through the cyclic nitrogen of pyridyl group.23 In the
ligand, bands observed at 2930 cm-1 and 2840 cm-1 were as-
signed for n(CH2) stretching vibrations were almost un-
shifted in all the complexes.24 In all the complexes two or
three bands attributed for n(SO) were observed in the range
of 1100-1045 cm-1 indicating the presence of S-bonded
sulphoxide moiety and non coordinated sulphoxide moi-
ety.25-27
Characterization of ruthenium complexes
Stoichiometries of complexes 1-7 are in agreement
with elemental analyses. Molecular weight of all the com-
plexes were confirmed by FAB-Mass spectra, where [M+
H]+ pseudo molecular ion peak was observed. Molar con-
ductance of all the complexes was recorded in water. For
the complex 1, 2, 5 and 6 it was found low in the range of
(62-69 W-1 cm2 mol-1), indicating their non-electrolytic na-
ture. However, for the complex 3, 4 and 7 it was found
comparatively high (116-123 W-1 cm2 mol-1), indicating
their ionic nature.17 Complex 1, 2, 5 and 6 are diamagnetic
(low spin d6, s=o), as expected for the low spin Ru(II) com-
plex. However, complex 3, 4 and 7 are paramagnetic with
magnetic moment 1.86-1.89 BM, (low spin d5, s = 1/2) as
expected for low spin Ru(III) complex.
1H-NMR and 13C{1H}-NMR spectra
1
In H-NMR of complex 1, three signals were ob-
served with 1:1:1 intensity at d 3.42 ppm, d 3.40 ppm and d
3.32 ppm attributed for three different environment of
methyl group of dmso. The signal at d 3.42 ppm and d 3.40
ppm for 12 proton each were assigned for methyl proton of
dmso trans to Cl and diastereotopic to each other.28 How-
ever, the third signal at d 3.32 ppm was assigned to methyl
proton of dmso trans to nitrogen of pyridine ring.29,30
13C{1H}-NMR of this complex also confirm this view by
exhibiting these signal at d 45.7 ppm, d 44.4 ppm and d
43.8 ppm for three environment of methyl carbon of dmso.
In complex 5 four signals with 1:1:1:3 intensity cen-
tered at d 4.58 ppm, d 4.30 ppm, d 3.56 ppm and d 2.27 ppm
were observed. The signal centered d 4.58 ppm and d 4.30
ppm for eight protons each were assigned to S-CH2 group
of tmso trans to nitrogen of pyridine ring. The signal at d
2.27 ppm for 24 protons was assigned to all S-C-CH2
group. 13C{1H}-NMR of this complex also exhibit three
signals centered at d 58.3 ppm, d 56.9 ppm and d 56.1 ppm
assigned for (S-C) carbon of tmso in three different envi-
ronment and three signals centered at d 25.5 ppm, d 25.4
ppm and d 25.1 ppm assigned for S-C-C carbon of tmso.
1H-NMR of complex 2 exhibits two signals with in-
tensity ratio 1:2 at d 3.43 ppm and d 3.39 ppm. The singlet
at d 3.43 ppm for twelve protons was assigned to methyl
proton of dmso trans to pyridyl nitrogen. However, signal
at d 3.39 ppm for 24 protons was attributed to methyl pro-
Electronic spectra
All Ru(II) complexes viz. 1, 2, 5 and 6, show four
bands in electronic spectra. The two absorption bands in
the visible region at 658-630 nm and 558-529 nm were due
to d-d transition, corresponding to the electronic transition
1
1A1g®1T1g and A1g®1T2g respectively. Higher extinc-
tion absorption band at about 422-356 nm in these com-
plexes was probably due to MLCT transition. However, ab-
sorption band at about 300 nm was assigned for p®p*
intraligand transition in the coordinated p-acidic imine
ligand.18-21
In electronic spectra of Ru(III) complexes viz. 3, 4
Fig. 1
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Synthesis, Characterization as Bis-chelating Bridging Ligand
ton of dmso trans to each other. 13C{1H}-NMR of this com-
plex also exhibit two signals assigned for (S-C) carbon of
dmso at d 46.8 ppm and d 45.4 ppm.29,30
However, 1H-NMR spectra of Ru(II) complex, 1 and
2 have additional sharp signal at about d 2.56 ppm, as-
signed for free (S-CH3) group of uncoordinated dmso. This
view is also supported by 13C{1H}-NMR spectra, where the
signal for the free (S-C) carbon was observed at about d
37.4 ppm.
Similarly, for complex 6, 1H-NMR spectrum exhibits
three sets of multiplet centered at d 3.66, d 3.46 and d 3.33
ppm. Signals centered at d 3.66 ppm and d 3.46 ppm was
assigned for the (S-CH2) protons in two different environ-
ments. Signal at d 3.33 ppm was assigned for (S-C-CH2)
protons of tmso ligand. Intensity ratio of these three signals
is 1:2:3. However, 13C{1H}-NMR spectrum of this com-
plex exhibit signals at d 58.8 ppm, assigned for the (S-C)
carbon trans to pyridine nitrogen and signal at d 57.4 ppm
was assigned for the (S-C) carbon trans to each other. The
signals at d 26.6 ppm and d 25.5 ppm were assigned for the
(S-C-C) carbon of tmso. So it can be concluded that one
tmso unit is trans to each other and other is trans to pyridyl
nitrogen in octahedral environment at both metal cen-
ter.31-33
In complex 5 and 6, two signals were observed at d
2.51 ppm and d 2.27 ppm, assigned for free (S-CH2) and
(S-C-CH2) of uncoordinated tmso group respectively. This
view is also in agreement with 13C{1H}-NMR spectra,
where these signals at about d 54.4 ppm and d 24.6 ppm
were attributed for free (S-C) and (S-C-C) carbon, respec-
tively; indicating the presence of uncoordinated dmso/tmso
in all Ru(II) complexes. 34,35
Thus on the basis of elemental analyses, FT-IR, UV-
VIS, 1H-NMR, 13C{1H}-NMR and FAB Mass studies the
most plausible structure for the Ru(II) complexes were sug-
gested in Fig. 2.
Fig. 2. Complex 1, 2, 5 and 6.
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The signal in NMR spectra of complexes 3, 4 and 7
were too broad and observed shifts were far away from the
original position, due to intervention of paramagnetic ion.
Thus on the basis of FT-IR, UV-VIS, FAB Mass and CHN
analyses, we suggest the most plausible structure of com-
plexes 3, 4 and 7 in Fig. 3. 3-D molecular structure of one
of the complex was also shown in Fig. 4.
ANTIBACTERIAL ACTIVITY
The antibacterial activity of ligand (A) and their
Fig. 4. 3D structure of Complex 1.
metal complexes 1-7 along with their precursor’s 1a-7a
have been tested on Escherichia coli, MTCC 1304, gram-
negative bacteria at different concentrations.
Mueller Hinton Agar (MHA) plates were prepared at
50 mL suspension of Escherichia coli, containing approxi-
mately 105 CFU (colony forming unit) were applied to the
plate by spread plate technique and by the Well diffusion
method.36-39 The wells made on the plate were filled with
50 mL of sample solution of 0.02%, 0.03% and 0.04% con-
centrations. Now, these plates were incubated at 37 1 °C
for 24-48 h in a refrigerated incubator shaker. Active zone
was measured in comparison to Chloramphenicol. Accord-
ing to results shown in Table 1 inhibition zone was very
small around the control compound (ligand A). However,
all complexes show more inhibition than their precursor,
probably due to increased lipophilicity in the complexes.40,41
The complex 3 and 4 were found more active than all other
complexes at 0.02% concentration.
CATALYTIC ACTIVITY
Ruthenium, complexes were found to have good cata-
lytic properties in many reactions such as decomposition of
hydrogen peroxide.42 In present investigation seven com-
plexes were tested for catalytic activity in hydrolysis of
benzonitrile. In a round bottom flask benzonitrile 1.5 mL
was added to the 25 mL of hydrogen peroxide. Reaction
mixture was stirred for five minutes. It turns milky white.
To this mixture 0.5 mL of 10% sodium hydroxide solution
was added and stirred for five minutes. Now reaction mix-
ture was refluxed, until the oily suspension of benzonitrile
was completely disappeared. Thereafter, reaction mixture
was allowed to cool. White shining crystals of benzamide
was obtained, which was then filtered, washed with water
Fig. 3. Complex 3, 4 and 7.
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Table 1. Antibacterial activity against Escherichia coli
*Diameter of
Activity against
S. No.
Compound / Precursor
Inhibition Zone (in
mm)
E. coli
A
1
5,5¢-methylenebis(pyridine), ligand
complex 1
+
+
-
14
20
06
26
07
34
15
32
12
19
07
22
07
31
08
40
1a
2
[cis, fac-RuCl2(S-dmso)4(O-dmso)]
complex 2
+
-
2a
3
[trans-RuCl2(dmso)4]
complex 3
[H(dmso)2]+[trans-RuCl4(dmso)2]-
+
+
+
+
+
-
3a
4
complex 4
(Na)+ [(trans-RuCl4(dmso)2]-
complex 5
4a
5
5a
6
[cis-RuCl2(tmso)4]
complex 6
+
-
6a
7
[trans-RuCl2(tmso)4]
complex 7
[H(tmso)2]+[trans-RuCl4(tmso)2]-
+
+
+
7a
8
Chloramphenicol
* Diameter of inhibition zone >8 mm is taken as active as shown as + in the table.
Table 2. Catalytic activity of the complexes
Media (Himedia) were used as received and routine sol-
vents were used without further purification for synthetic
purposes.
Amount in
Yield of
Complexes
*Turnover
(m Mols)
product (%)
Electronic absorption spectra were recorded with
Shimadzu-1700 PC. Conductivity measurements were car-
ried out at 25 ºC on an EI-181 conductivity bridge with a
dipping type cell. FT-IR spectra were recorded in KBr pel-
lets on Shimadzu-8400 PC, FT-IR spectrophotometer. 1H-
NMR and 13C{1H}-NMR spectra were recorded in solvent
CDCl3 on a Bruker Avance-400 NMR spectrometer. FAB-
Mass spectra were recorded on Jeol SX-102 Mass spec-
trometer. Chem Draw Ultra 8.0 and Chem 3D Ultra 8.0
software have been used for molecular structure. Gouy’s
method was employed for measurement of magnetic sus-
ceptibility. Cobalt mercurytetrathiocyanate was used as
standard. Diamagnetic correction was made using Pascal’s
constant.
Control Reaction
complex 1
complex 2
complex 3
complex 4
complex 5
complex 6
complex 7
-
50
62
68
68
64
62
70
63
-
82
82
88
82
91
91
93
112
121
114
115
99
112
100
* Moles of product per moles of catalysts
and kept for dry. Very little amount of benzamide was iso-
lated also from mother liquor after vacuum evaporation.
When complex was added to the reaction mixture in
micro moles (82-93) and whole procedure were repeated, it
was found that; time of completion of reaction was less in
comparison to the control reaction. The yield of benzamide
was also increased in each case. Results show that complex
2, 3 and 6 exhibit high catalytic activity. The result of cata-
lytic activity is shown in Table 2.
Synthesis of 5,5¢-methylenebis(pyridine)
The ligand was synthesized in three steps
(a) Preparation of 5,5¢-methylenebis(2-aminopyridine)
The ligand 5,5¢–methylenebis(2-aminopyridine) was
prepared according to the procedure reported by Pradeep
et. al.24 The 2-aminopyridine (0.941 g, 0.01 mol) was dis-
solved in distilled water (~25 mL) in a round bottom flask.
To this solution formaldehyde (0.14 mL, 0.005 mol) was
added with constant stirring. The reaction mixture was
stirred for 2 h. A cream colour precipitate was obtained,
EXPERIMENTAL SECTION
RuCl3.3H2O (E. Merck), 2-aminopyridine (Himedia),
tetramethylenesulphoxide (Aldrich, USA), analytical
grade dimethylsulfoxide (E. Merck), Mueller Hinton Agar
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which was filtered off, washed with distilled water. The
solid was recrystallized from ethanol. Mp, 92-93 oC.
(b) Preparation of Tetrazonium Salt
n(CH2), 2960 (m), 2720 (s); n(C=C) + (C=N), 1658 (s),
1572 (m), 1520 (s); n(SO), 1090 (s), 1056 (s); n(Ru-S), 425
1
(m); H-NMR Spectra (d value in ppm); d (Ar-H), 8.30-
The 5,5¢-methylenebis(2-aminopyridine), (0.500 g,
0.002 mol) was dissolved in 0.24 mL dil. HCl (0.006 N) in a
beaker. To this solution NaNO2 (0.331 g, 0.004 mol) and 6
mL distilled water was added in an ice bath at about ~5 oC.
A yellow colour solid was obtained which was dried. Mp,
150 oC, Yield, 0.263 g (50%).
7.63 (6H, m); d (CH3), 3.42 (12H, s), 3.40 (12H, s), 3.32
(12H, s), 2.56 (30H, s) d (CH2), 2.86 (2H, s); 13C{1H}-
NMR Spectra (d value in ppm): d (Ar-C), 139.6-147.7; d
(S-C), 45.7, 44.4, 43.8, 37.4; d (CH2), 38.8; FAB-Mass
[M+H]+ m/z = 1218. Dm at 25 °C (W-1 cm2 mol-1): 69 in
CDCl3. Calcd for C29H64N2S9O9Cl4Ru2 (Mt = 1217): C,
28.61; H, 5.30; N, 2.30; S, 23.71. Found: C, 28.62; H, 5.31;
N, 2.32; S, 23.73.
(c) Preparation of ligand [5,5¢-methylenebis(pyridine)]
The prepared tetrazonium salt (0.2629 g, 0.009 mol)
was dissolved in methanol (10 mL) in a round bottom flask.
The solution was stirred for 4 h. The reaction mixture was
refluxed for 6 h. The reddish brown colour solution was ob-
tained. The solution was cooled and concentrated in vac-
uum. Areddish brown colour compound was obtained. The
solid was recrystallized from 2:1:3 water-ethanol-diethyl-
ether (v/v) mixture. Yield, 0.112 g (73%), Mpd; 105 oC. Se-
lected infrared absorption (KBr, cm-1): n(CH2), 2930 (m),
2840 (s); n(C=C) + (C=N), 1608 (s), 1560 (s), 1508 (s);
1H-NMR Spectra (d value in ppm); d (Ar-H), 8.12-7.60
(6H, m), d (CH2), 2.78 (2H, s); 13C{1H}-NMR (d value in
ppm); d (Ar-C), 136.8-148.3, d (CH2), 38.9; FAB-Mass
[M+H]+ m/z = 171. Calcd for C11H10N2 (Mt = 170): C,
77.62; H, 5.92; N, 16.46. Found: C, 77.63; H, 5.94; N,
16.47.
Synthesis of [{trans,mer-RuCl2(dmso)3}2(µ-5,5¢-methyl-
enebis(pyridine))]. 3 dmso; Complex 2
The precursor [trans-RuCl2(dmso)4] was prepared
by procedure cited in literature.44 Recrystallized [trans-
RuCl2(dmso)4], (0.087 g, 0.18 mmol) was dissolved in
methanol (~5 mL) in a two neck flask. The ligand 5,5¢-
methylenebis(pyridine), (0.0308 g, 0.18 mmol), dissolved
in methanol (~5 mL) was added to the reaction mixture and
stirred for 2 h. The colour of solution becomes red brown.
To the above solution, recrystallized [trans-RuCl2(dmso)4],
(0.087 g, 0.18 mmol) dissolved in methanol (~5 mL) was
added and stirred for 10 h. Dark red brown colour solution
was obtained. Reaction mixture was refluxed for 2 h. The
reaction mixture was vacuum evaporated and recrystal-
lized from 2:1:1 ethanol-methanol-water (v/v) mixture.
o
Synthesis of Ruthenium complexes
Yield; 0.169 g (77%); Mpd; 170 C. Electronic Spectra
Synthesis of [{cis-RuCl2(dmso)3}2(µ-5,5¢-methylenebis-
(pyridine))]. 3 dmso; Complex 1
(lmax, nm (e in M-1 cm-1) in CDCl3; 652 (72), 558 (95),
356 (589), 296 (849). Selected infrared absorption (KBr,
cm-1): n(CH2), 2880 (w), 2810 (sh); n(C=C) + (C=N), 1627
(s), 1590 (s), 1530 (s), n(SO), 1097 (s), 1059 (s); n(Ru-S),
The precursor complex, [cis, fac-RuCl2(S-dmso)3(O-
dmso)] was prepared according to procedure cited in litera-
ture.43 The recrystallized [cis, fac-RuCl2(S-dmso)3(O-
dmso)], (0.097 g, 0.20 mmol) was dissolved in methanol
(~5 mL) taken in a round bottom flask. To the above solu-
tion 5,5¢-methylenebis(pyridine), (0.034 g, 0.20 mmol)
dissolved in methanol (~5 mL) was added. Reaction mix-
ture was stirred for 1 h. Yellow colour changed into pale
yellow. Recrystallized [cis, fac-RuCl2(S-dmso)3(O-dmso)],
(0.097 g, 0.20 mmol), dissolved in methanol (~5 mL) was
added to the above reaction mixture. The above solution
was stirred for 7 h. Dark yellow colour solution was ob-
tained which was refluxed for 3 h. The light yellow solid
was obtained on vacuum evaporation. Yellow solid was
recrystallized from 1:2 ethanol-methanol, (v/v) mixture.
1
442 (s). H-NMR Spectra, (d value in ppm): d (Ar-H),
7.98-7.51 (6H, m); d (CH3), 3.43 (12H, s), 3.39 (24H, s),
2.49 (30H, s); d (CH2), 2.82 (2H, s), 13C{1H}-NMR Spectra
(d value in ppm): d (Ar-C), 126.1-136.4; d (S-C), 46.8,
45.4, 36.2; d (CH2), 38.9; FAB-Mass [M+H]+ m/z = 1218.
Dm at 25 °C (W-1 cm2 mol-1): 65 in water. Calcd for
C29H64N2S9O9Cl4Ru2 (Mt = 1217): C, 28.61; H, 5.30; N,
2.30; S, 23.71. Found: C, 28.64; H, 5.33; N, 2.31; S, 23.75.
Synthesis of [H(dmso)2]2+ [trans-RuCl4(dmso)(m-5,5¢-
methylenebis(pyridine))]2-; Complex 3
The precursor [H(dmso)2]+[trans-RuCl4(dmso)2]-
was prepared according to the procedure given by Alessio
et al.17 Recrystallized [H(dmso)2]+[trans-RuCl4(dmso)2]-,
(0.0445 g, 0.079 mmol) was dissolved in methanol (~5 mL)
in a two neck flask. The ligand 5,5¢-methylenebis(2-hy-
droxypyridine), (0.0136 g, 0.079 mmol) dissolved in meth-
o
Yield; 0.193 g (79%); Mpd; 165 C. Electronic Spectra
(lmax, nm (e in M-1cm-1) in CDCl3; 658 (80), 541 (84), 395
(678), 299 (756); Selected infrared absorption (KBr, cm-1):
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Synthesis, Characterization as Bis-chelating Bridging Ligand
anol (~5 mL) was added to the above solution. The reaction
mixture was stirred for 1 h. Dirty brown colour was ob-
served. To this solution, recrystallized [H(dmso)2]+[trans-
RuCl4(dmso)2]- (0.0445 g, 0.079 mmol) dissolved in meth-
anol (~5 mL) was added and stirred for 12 h. A yellow-
brown colour solution was obtained which was vacuum
evaporated. The solid was recrystallized from 2:1:1 etha-
nol-methanol-water (v/v) mixture. Yield; 0.0579 g (64%);
Mpd; 130 oC. Electronic Spectra (lmax, nm (e in M-1 cm-1)
in water; 666 (81), 468 (111), 379 (421), 302 (815); Se-
lected infrared absorption (KBr, cm-1): n(CH2), 2965 (s),
2845 (sh); n(C=C) + (C=N), 1665 (s), 1623 (s), 1548 (s);
n(SO), 1096 (w), 1026 (s); FAB-Mass [M+H]+ m/z = 1127;
Dm at 25 °C (W-1 cm2 mol-1): 123 in water. Calcd for
C23H48N2S6O6Cl8Ru2 (Mt = 1126): C, 24.52; H, 4.29; N,
2.49; S, 17.08. Found: C, 24.54; H, 4.31; N, 2.54; S, 17.15.
Synthesis of [Na]2+ [trans-RuCl4(dmso)(m-5,5¢-methyl-
enebis(pyridine))]2-; Complex 4
The precursor [Na]+[trans-RuCl4(dmso)2]- was pre-
pared according to the procedure reported in literature.17
Recrystallized [Na]+[trans-RuCl4(dmso)2]-, (0.046 g,
0.109 mmol) was dissolved in methanol (~5 mL) in a two
neck flask. The ligand 5,5¢-methylenebis(pyridine), (0.0186
g, 0.109 mmol) dissolved in methanol (~5 mL) was added
to the above reaction mixture. The above reaction mixture
was stirred for 1 h. The colour changed into fluorescent
yellow. To the above solution recrystallized [(Na)]+[trans-
RuCl4(dmso)2]- (0.046 g, 0.109 mmol) dissolved in metha-
nol (~5 mL) was added and stirred for 9 h. The colour be-
came dirty yellow. The reaction mixture was refluxed for 2
h. Dark yellow colour solution was obtained. After few
hours the colour was changed into yellow green. The solu-
tion was evaporated and recrystallized from ethanol-meth-
anol, 2:1 (v/v) mixture. Yield; 0.079 g (87%); Mpd; 125 °C.
Electronic Spectra (lmax, nm (e in M-1cm-1) in water; 589
(64), 459 (116), 374 (513), 304 (638). Selected infrared ab-
sorption (KBr, cm-1): n(CH2), 2955 (s), 2820 (s); n(C=C) +
(C=N), 1645 (s), 1532 (m), 1525 (m); n(SO), 1086, 1025
(s), 1019 (s); n(Ru-S), 418 (s). FAB-Mass [M+H]+ m/z =
813. Dm at 25 °C (W-1 cm2 mol-1): 120 in water. Calcd for
C15H22N2S2O2Na2Cl8Ru2 (Mt = 812): C, 22.18; H, 2.73; N,
3.45; S, 7.90. Found: C, 22.21; H, 2.68; N, 3.47; S, 7.88.
Synthesis of [{cis,fac-RuCl2(tmso)3}2(µ-5,5¢-methylene-
bis(pyridine))]. 3 tmso; Complex 5
(0.599 g, 1.018 mmol) was dissolved in methanol (~5 mL)
in a two neck flask. The ligand 5,5¢-methylenebis(pyri-
dine), (0.173 g, 1.018 mmol) dissolved in methanol (~5
mL) was added to the above reaction mixture and stirred
for 1 h. The yellow colour became red-yellow colour. To
this reaction mixture recrystallized [cis-RuCl2(tmso)4],
(0.599 g, 1.018 mmol) dissolved in methanol (~5 mL) was
added and stirred for 12 h. Dark red brown colour solution
was obtained. Reaction mixture was vacuum evaporated
and the solid obtained was recrystallized from ethanol-
methanol-water 1:1:1, (v/v) mixture. Yield; 1.101 g (75%);
Mpd; 115 oC; Electronic Spectra (lmax, nm (e in M-1cm-1)
in water; 644 (61), 529 (96), 422 (583), 301 (832). Selected
infrared absorption (KBr, cm-1): n(CH2), 2910 (m), 2690
(s); n(C=C) + (C=N), 1650 (s), 1592 (s), 1535 (s); n(SO),
1
1100 (s), 1066 (s), 1032 (s); n(Ru-S), 420 (s); H-NMR
Spectra (d value in ppm); d (Ar-H), 8.05-7.72 (6H, m); d
(S-CH2), 4.58 (8H, m), 4.30 (8H, m), 3.56 (8H, m), 2.51
(20H, m); d (CH2), 2.79 (2H, s); d (S-C-CH2), 2.27 (24H,
m), 2.18 (20H, m); 13C{1H}-NMR Spectra (d value in
ppm); d (Ar-C), 135.6-128.3; d (S-C), 58.3, 56.9, 56.1,
48.7; d (CH2), 38.7; d (S-C-C), 25.5, 25.4, 25.1, 24.2; FAB-
Mass [M+H]+ m/z = 1452; Dm at 25 °C (W-1 cm2 mol-1): 62
in water. Calcd for C47H82N2S9O9Cl4Ru2 (Mt = 1451): C,
38.89; H, 5.69; N, 1.93; S, 19.88. Found: C, 38.91; H, 5.71;
N, 2.01; S, 19.90.
Synthesis of [trans,mer-RuCl2(tmso)3]2(µ-5,5¢-methyl-
enebis(pyridine))]. 3 tmso; Complex 6
The starting material [trans-RuCl2(tmso)4] was pre-
pared from the recrystallized [trans-RuCl2(dmso)4] ac-
cording to procedure given in literature.45 The recrystal-
lized [trans-RuCl2(tmso)4], (0.0521 g, 0.088 mmol) was
dissolved in methanol (~5 mL) in a two neck flask. The
ligand 5,5¢-methylenebis(pyridine), (0.0150 g, 0.088
mmol) dissolved in methanol (~5 mL) was added to the re-
action mixture and stirred for 1 h. The colour changed into
red orange. To this reaction mixture, recrystallized [trans-
RuCl2(tmso)4] (0.0521 g, 0.088 mmol) dissolved in metha-
nol (~5 mL) was added and stirred for 11 h. The colour of
solution became red brown. The reaction mixture was vac-
uum evaporated to yield brown colour solid, which was
washed from 1:1:2 ethanol-methanol-water (v/v) mixture.
o
Yield; 0.089 g (76%); Mpd; 115 C; Electronic Spectra
(lmax, nm (e in M-1cm-1) in water; 630 (51), 550 (92), 369
(399), 289 (841). Selected infrared absorption (KBr, cm-1):
n(CH2), 2860 (m), 2841 (w); n(C=C) + (C=N), 1630 (s),
1597 (s), 1540 (s); n(SO), 1115 (s), 1095 (s), 1024 (s); 1H-
The precursor [cis-RuCl2(tmso)4] was prepared from
the recrystallized [cis-RuCl2(dmso)4], according to proce-
dure cited in literature.45 Recrystallized [cis-RuCl2(tmso)4],
J. Chin. Chem. Soc. 2012, 59, 485-493
© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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491

Article
Shukla et al.
NMR Spectra (d value in ppm); d (Ar-H), 8.68-7.80 (6H,
m); d (S-CH2), 3.66 (16H, m), 3.46 (8H, m), 2.59 (20H, m);
d (S-C-CH2), 3.33 (24H, s), 2.18 (20H, m); d (CH2), 2.75
(2H, s); 13C{1H}-NMR Spectra (d value in ppm); d (Ar-C),
127.5-146.6; d (S-C), 58.8, 57.4, 56.6; d (CH2), 39.7; d
(S-C-C), 26.6, 25.5, 24.3; FAB-Mass [M+H]+ m/z = 1452;
Dm at 25 °C (W-1 cm2 mol-1): 64 in water. Calcd for
C47H82N2S9O9Cl4Ru2 (Mt = 1451): C, 38.89; H, 5.69; N,
1.93; S, 19.88. Found: C, 38.91; H, 5.71; N, 2.01; S, 19.90.
ence College, Jabalpur (M.P.) and Head, Department of
Chemistry, Govt. Model Science College, Jabalpur (M.P.)
for providing Laboratory facilities. We are thankful to
SAIF, CDRI, Lucknow for C, H, N, S analysis and FAB-
1
mass spectra and DMSRDE, Kanpur for recording H-
NMR, 13C{1H}-NMR, spectra. We are indebted to HOD
Chemistry, RDVV, Jabalpur (M.P.) for their help in re-
cording FT-IR spectra.
+
Synthesis of [H(tmso)]2 [{trans-RuCl4(tmso)}2(m-5,5¢-
methylenebis(pyridine)]2-; Complex 7
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CONCLUSION
Seven dinuclear ruthenium complexes have been
synthesized by the reaction of 5,5¢-methylenebis(pyridine),
spacer with different ruthenium precursor. Reaction of a
precursor with spacer ligand in 2:1 molar ratio replaced the
one sulphoxide and linked two metal centers. The ligand
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specific structure and biological activity. These complexes
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ACKNOWLEDGEMENT
We are thankful to our Principal Govt. Model Sci-
492
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J. Chin. Chem. Soc. 2012, 59, 485-493

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