New multifunctional complexes [Ru(κ3-L)(EPh 3)2CI]+ [E = P, As; L = 2,4,6-Tris(2-pyridyl)- 1,3,5-triazine] containing both group v and polypyridyl ligands

Article abstract of DOI:10.1002/ejic.200400069

Synthesis, structure, reactivity and enzyme inhibitory activity of the new cationic ruthenium complexes [Ru(κ³-L)(EPh₃) ₂CI]BF₄ [L = 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz); E = P (1), As (2)] and their subs

Full text of DOI:10.1002/ejic.200400069

FULL PAPER
New Multifunctional Complexes [Ru(κ3-L)(EPh3)2Cl]؉ [E ؍ P, As;
L ؍ 2,4,6-Tris(2-pyridyl)-1,3,5-triazine] Containing both Group
V
and
Polypyridyl Ligands
Sanjeev Sharma,[a] Manish Chandra,[a] and Daya Shankar Pandey*[a]
Keywords: Ruthenium / Tertiary phosphanes / 2,4,6-Tris(2-pyridyl)-1,3,5-triazine / DNA / Topoisomerase II
Synthesis, structure, reactivity and enzyme inhibitory activity
of the new cationic ruthenium complexes [Ru(κ3-
L)(EPh3)2Cl]BF4 [L = 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz);
E = P (1), As (2)] and their substitution products [Ru(κ3-
tptz)(PPh3)(dtc)]Cl (3), [Ru(κ3-tptz)(PPh3)(CN)2] (4), [Ru(κ3-
tptz)(AsPh3)(dtc)]BF4 (5), and [Ru(κ3-tptz)(AsPh3)(CN)2] (6)
observed in these complexes. Further studies indicated that
the complexes [Ru(κ3-L)(EPh3)2Cl]+ could find application as
precursors in the synthesis of other ruthenium complexes or
as metallo-ligands. The complexes also interact with DNA,
which was illustrated by absorption titration studies with CT-
DNA and inhibition of topoisomerase II of the filarial parasite
are reported. The complexes were characterized by analyt- Setaria cervi.
ical and spectroscopic methods and the structures of the com-
plexes 1, 2 and 3 determined by X-ray diffraction studies.
C−H···X (X = Cl, F and S), C−H···π and π−π interactions were
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
opportunity to behave as metallo-ligands because of the
presence of vacant donor sites at the tptz ligand and, thus,
could find applications in the synthesis of homo-, heterodi-
or polynuclear systems. Furthermore, DNA binding studies
have shown that ruthenium complexes containing polypyri-
dyl ligands are of significant importance.[5] It was felt that
the new complexes of the series [Ru(κ3-L)(EPh3)2Cl]ϩ could
be used as DNA probes. Although, a number of reports
dealing with DNA binding and inhibition activity of (poly-
pyridyl)RuII complexes are available in the literature, ac-
tivity of the complexes incorporating triphenylphosphane
or triphenylarsane and a polypyridyl ligand have yet to be
examined. We report herein, on the reactivity, absorption
titration studies and inhibitory activity against DNA topo
II of the filarial parasite Setaria cervi of the new, air-stable
mononuclear complexes [Ru(κ3-tptz)(L2)Cl]ϩ.
Recently, (polypyridyl)RuII complexes have received con-
siderable attention owing to their possible application in
conversion of solar energy to electrical energy,[1] in long-
range electron and energy transfer,[2] molecular electronic
devices,[3] self-assembly processes[4] and as photoprobes for
DNA.[5] Polypyridyl bridging ligands containing a delo-
calized π-electron system have drawn special attention in
this regard. Using such ligands, many luminescent and re-
dox-active compounds have been synthesized and studied
extensively.[6] During the past few years, we have been inter-
ested in the synthesis and characterization of metallo-li-
gands/synthons based on organometallic systems contain-
ing organonitriles and polypyridyl ligands.[7] During our
studies on the reactivity of hydrated RuIII chloride in the
presence of excess EPh3 or [RuCl2(PPh3)3] with 2,4,6-tris(2-
pyridyl)-1,3,5-triazine (tptz), we have isolated a completely
new series of cationic complexes [Ru(κ3-L)(EPh3)2Cl]ϩ.
These compounds are examples of ruthenium complexes
containing both Group V and polypyridyl ligands, which
are associated with classical coordination chemistry.
Results and Discussion
The air-stable cationic complexes 1, 2 and their represen-
tative substitution products [Ru(κ3-tptz)(PPh3)(dtc)]Cl (3),
[Ru(κ3-tptz)(PPh3)(CN)2] (4), [Ru(κ3-tptz)(AsPh3)(dtc)]BF4
(5), and [Ru(κ3-tptz)(AsPh3)(CN)2] (6) were obtained in ex-
cellent yield as shown in Scheme 1. The compounds were
characterized spectroscopically and gave satisfactory el-
emental analyses. The microanalyses, FAB-MS and NMR
(1H and 31P) data of the complexes correspond to their re-
spective formulas.
The new cationic complexes [Ru(κ3-L)(EPh3)2]Cl]ϩ all
possess κ3-bonded tptz, two tertiary phosphane or arsane
ligands, a labile chloro group, and have the potential to ex-
hibit rich chemistry. The ligand tptz primarily acts as a tri-
dentate ligand similar to terpyridine (tpy), but is more ver-
satile than tpy. The complexes under study offer a unique
[a]
Department of Chemistry, Awadhesh Pratap Singh University,
Rewa 486003 (M.P.), India
E-mail: dsprewa@yahoo.com
1H NMR spectroscopic data of the complexes are given
in the Exp. Sect. The positions and integrated intensities of
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DOI: 10.1002/ejic.200400069
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S. Sharma, M. Chandra, D. S. Pandey
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Scheme 1
the signals corresponding to tptz corroborated well with a exhibited reversible (RuII/III) metal-based oxidation couples
system containing two magnetically equivalent coordinated at 1.05 (70) V and 1.02 (50) V, respectively.[8] In the cathodic
pyridyl rings and one uncoordinated pyridyl ring. This ob- potential window, three ligand-based reversible and quasi-
servation indicated coordination of the tptz to Ru in a κ3- reversible reduction couples were observed in the range
manner. The aromatic protons of the PPh3 and AsPh3 li- 0.89Ϫ1.50 V for the tptz ligand.
gands gave a broad multiplet in the usual region with δ ϭ
7.26Ϫ7.07 ppm. Integrated intensities and positions of the
signals were consistent with the respective formulas of the
complexes. The main feature of the 1H NMR spectra of the
diethyl dithiocarbamate containing complexes 3 and 4 is the
presence of multiplet signals at high field with chemical
shifts characteristic of methyl and methylene protons. In the
complexes 3 and 4, these appeared at δ ϭ 4.10 (q, J ϭ
7.2 Hz, 2 H), 3.62 (q, J ϭ 6.9 Hz, 2 H), 1.52 (t, J ϭ 7.2 Hz,
3 H), 1.13 (t, J ϭ 6 Hz, 3 H) and 4.03 (q, J ϭ 7.2 Hz, 2 H),
3.55 (q, J ϭ 7.2 Hz, 2 H), 1.50 (t, J ϭ 7.2 Hz, 3 H), 1.10
(t, J ϭ 6.1 Hz, 3 H) ppm, respectively. The presence of sig-
Figure 1. Cyclic voltammogram of the complex 2
nals in this region strongly suggests coordination of the di-
ethyl dithiocarbamate to the metal center. In the 31P{1H}
NMR spectra of the complexes 1, 3 and 5, single sharp
In the electronic absorption spectra of complexes 1 and
resonances were observable at δ ϭ 16.24, 37.81 and 2, the MLCT transitions appeared in the visible region at λ
32.89 ppm, respectively. The presence of a single sharp peak (ε) ϭ 472 (24022) and 489 (6930) nm, respectively, while
in the 31P{1H} NMR spectrum of complex 1 suggests that the ligand-centered transitions were observed at λ (ε) ϭ 309
both the 31P nuclei are chemically equivalent and that the (63759), 273 (149195) (for 1) and 342 (7250), 271.5 (21355)
triphenylphosphane ligands are trans-disposed in this com- (for 2) nm. Complexes 3Ϫ6 exhibited red-shifted absorp-
plex.
tions when compared with complexes 1 and 2. The com-
Electrochemical properties of the new complexes were plexes do not luminesce in air at room temperature.
observed by cyclic voltammetry. The cyclic voltammogram
Molecular structures of complexes 1Ϫ3 were established
of complex [Ru(κ3-tptz)(AsPh3)2Cl]BF4 (2) is shown in Fig- crystallographically.[9] Both complexes 1 and 2 crystallize in
ure 1. The ruthenium complexes with the tptz ligand the P21/c space group, while complex 3 crystallizes in a very
[Ru(κ3-tptz)(PPh3)2Cl]BF4 and [Ru(κ3-tptz)(AsPh3)2Cl]BF4 rare F2dd space group (Table 3). In all the complexes, Ru is
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New Multifunctional Complexes [Ru(κ3-L)(EPh3)2Cl]ϩ
FULL PAPER
bonded covalently within the major coordination sites of ordinated pyridyl ring is inclined from the coordinated part
tptz in a κ3-manner by two phosphorus or arsenic atoms of the ligand tptz by 25.9 and 23.3°, respectively. In com-
from the triphenylphosphane or arsane ligand and a chloro plex 3, which is obtained by replacement of one PPh3 ligand
group in complex 1 and 2 and one phosphorus atom from and the chloro group of complex 1 by a dithiocarbamate
the triphenylphosphane ligand and a dithiolato group in ligand, the tptz ligand has regained its planarity. This is
complex 3. There is a distorted octahedral coordination ge- suggested by the angle of inclination (2.4°).
ometry about the ruthenium center. The N(1)ϪRu(1)ϪN(2)
Selection of ligands plays an important role amongst the
and N(2)ϪRu(1)ϪN(3) angles in complex 1 are essentially factors that induce the self-assembly processes. The ligands
equal with 78.77(12) and 78.47(11)°, while in complexes 2 EPh3 and triazine are expected to show different propen-
and 3 these angles are 78.91(13) and 78.44(12)° and 76.9(5) sities for molecular arrangement based on the stacking ar-
and 77.1(5)°, respectively. This suggests some inward bend- rangement of phenyl or triazine rings. The X-ray structure
ing of the coordinated pyridyl group and may be the reason for complexes 1Ϫ3 revealed intermolecular CϪH···X (X ϭ
for the observed distortion. The bond length of Ru(1) to
˚
the central triazine nitrogen atom Ru(1)ϪN(2) in complex
Table 2. Selected hydrogen bond lengths [A] and angles [°] for the
˚
1 is 1.936(3) A, which is shorter than the bond of Ru(1) to complex 1Ϫ3
the coordinated pyridyl nitrogen atom Ru(1)ϪN(1)
˚
˚
DϪHϪA
d(DϪH) d(HϪA) d(DϪA) Є(DHA)
[2.110(3) A] and Ru(1)ϪN(3) [2.103(3) A]. Similarly, in
˚
complexes 2 and 3 Ru(1)ϪN(2) is 1.931(3) and 1.968(13) A,
1
and the Ru(1)ϪN(1) and Ru(1)ϪN(3) distances are
˚
˚
2.098(3), 2.099(3) A and 2.099(17), 2.076(13) A, respec-
tively. The RuϪN bond lengths are consistent with a κ3-
coordination of tptz and similar to those reported for other
(tptz)RuII complexes.[10] The triphenylphosphane ligands in
complex 1 and the triphenylarsane ligands in complex 2 are
trans-disposed as indicated by the P(1)ϪRu(1)ϪP(2) angle
of 178.52(3)° and As(1)ϪRu(1)ϪAs(2) angle of 178.26(2)°.
The Ru(1)ϪP(1) and Ru(1)ϪP(2) distances are 2.4130(11)
C(8)ϪH(8)ϪCl(1)
C(14)ϪH(14)ϪCl(1)
C(24)ϪH(24)ϪCl(1)
C(26)ϪH(26)ϪCl(1)
0.93
0.93
0.93
0.93
2.69
2.72
2.71
2.81
2.51
2.53
3.536(4)
3.566(4)
3.411(5)
3.669(4)
3.041(8)
3.443(7)
151.9
152.3
132.7
153.7
116.1
165.7
C(39)ϪH(39)ϪF(3)[a] 0.93
C(43)ϪH(43)ϪF(2)[b] 0.93
2
C(39)ϪH(39)ϪF(1)[a] 0.84(7)
2.44(7)
2.82
3.084(9)
3.671(5)
134(6)
151.8
˚
and 2.4264(11) A in complex 1, while in complex 2 the
C(8)ϪH(8)ϪCl(1)
0.93
Ru(1)ϪAs(1) and Ru(1)ϪAs(2) distances are 2.481(6) and
˚
2.491(6) A, respectively. In complex 3, the Ru1ϪS1 and
3
˚
Ru1ϪS2 distances are 2.427(4) and 2.407(4) A, respectively.
These are essentially equivalent or similar to those in re-
lated complexes.[11] The RuϪCl distances in both complexes
1 and 2 are normal and are similar to RuϪCl distances in
other complexes (Table 1).[12]
The triazine ring from tptz and the coordinated pyridyl
rings are almost coplanar. In complexes 1 and 2, the unco-
C(15)ϪH(15)ϪN(4)
C(20)ϪH(20A)ϪS(1) 0.97
C(22)ϪH(22B)ϪS(2) 0.97
C(25)ϪH(25)ϪS(2)
C(37)ϪH(37)ϪS(2)
0.93
2.47
2.53
2.61
2.70
2.77
2.79(2)
3.10(2)
2.98(2)
3.477(19) 142.0
3.615(19) 151.0
100.4
117.3
103.0
0.93
0.93
[a]
[b]
x, y, z. x, y, z ϩ 1.
˚
Table 1. Selected bond lengths [A] and angles [°] for complexes 1Ϫ3
1
2
3
Ru(1)ϪCl(1)
Ru(1)ϪP(1)
Ru(1)ϪP(2)
Ru(1)ϪN(1)
Ru(1)ϪN(2)
Ru(1)ϪN(3)
N(2)ϪRu(1)ϪN(1)
N(3)ϪRu(1)ϪN(2)
N(1)ϪRu(1)ϪCl(1)
N(2)ϪRu(1)ϪCl(1)
N(3)ϪRu(1)ϪCl(1)
P(1)ϪRu(1)ϪCl(1)
P(2)ϪRu(1)ϪCl(1)
P(2)ϪRu(1)ϪP(1)
N(4)ϪC(49)ϪC(50)ϪN(6)
2.4473(11)
2.4130(11)
2.4264(11)
2.110(3)
1.936(3)
2.103(3)
78.77(12)
78.47(11)
103.31(9)
177.16(9)
99.48(8)
91.21(4)
89.44(4)
Ru(1)ϪCl(1)
Ru(1)ϪAs(1)
Ru(1)ϪAs(2)
Ru(1)ϪN(1)
Ru(1)ϪN(2)
Ru(1)ϪN(3)
N(2)ϪRu(1)ϪN(1)
N(3)ϪRu(1)ϪN(2)
N(1)ϪRu(1)ϪCl(1)
N(2)ϪRu(1)ϪCl(1)
N(3)ϪRu(1)ϪCl(1)
As(1)ϪRu(1)ϪCl(1)
As(2)ϪRu(1)ϪCl(1)
As(2)ϪRu(1)ϪAs(1)
2.443(11)
2.481(6)
2.491(6)
2.098(3)
1.931(3)
Ru(1)ϪN(1)
Ru(1)ϪN(2)
Ru(1)ϪN(3)
Ru(1)ϪP(1)
Ru(1)ϪS(1)
Ru(1)ϪS(2)
S(1)ϪC(19)
S(2)ϪC(19)
2.099(17)
1.968(13)
2.076(13)
2.323(4)
2.427(4)
2.407(4)
1.758(18)
1.66(2)
1.37(2)
76.9(5)
77.1(5)
94.4(4)
72.54(15)
94.09(14)
98.9(4)
113.6(11)
Ϫ3(3)
2.099(3)
78.91(13)
78.44(12)
102.45(10)
178.15(9)
100.21(9)
91.14(3)
90.40(3)
178.26(2)
Ϫ156.7(4)
N(7)ϪC(19)
N(1)ϪRu(1)ϪN(2)
N(2)ϪRu(1)ϪN(3)
N(2)ϪRu(1)ϪP(1)
S(1)ϪRu(1)ϪS(2)
P(1)ϪRu(1)ϪS(2)
S(1)ϪRu(1)ϪN(2)
S(2)ϪC(19)ϪS(1)
178.52(3)
154.1(4)
N(4)ϪC(49)ϪC(50)ϪN(6)
C(22)ϪN(7)ϪC(19)ϪS(2)
N(4)ϪC(13)ϪC(14)ϪN(6)
177.6(15)
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S. Sharma, M. Chandra, D. S. Pandey
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Figure 2. (a) Molecular structure of [Ru(κ3-tptz)(PPh3)2]Cl]ϩ (1); (b) molecular structure of [Ru(κ3-tptz)(AsPh3)2]Cl]ϩ (2); (c) molecular
structure of [Ru(κ3-tptz)(PPh3)(dtc)]ϩ (3)
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New Multifunctional Complexes [Ru(κ3-L)(EPh3)2Cl]ϩ
FULL PAPER
F, N, S and Cl) and πϪπ interactions. (Table 2) Complex 1 of the complexes were used for DNA binding and inhibition
shows CϪH···Cl intramolecular interactions, which involve studies. It is well documented that nonplanar octahedral
Cl and an adjacent hydrogen atom attached to the phenyl complexes can partially intercalate with the DNA helix or
(PPh3) rings. However, this type of interaction is not appar- they can show groove binding interactions with the major
ent in complex 2 which has an analogous structure. The or minor groove of the helix.[14] Fixed amounts of metal
absence of a CϪH···Cl type interaction is probably due to complexes [13.3 µ (1) and 40 µ (2)] were titrated with
the longer RuϪAs bond in complex 2 when compared with an increasing amount of CT-DNA over a range of DNA
the RuϪP distance in complex 1. The importance of πϪπ concentrations from 0 to 112 µ.[15] Absorption spectra
stacking interactions between aromatic rings, which lie in were measured after equilibration and the binding con-
˚
the range 3.4Ϫ3.5 A, has widely been recognized in the in- stants of the complexes with CT-DNA were determined by
tercalation of drugs with DNA[13] in biological systems. In monitoring the decay in absorbance with increasing DNA
all the complexes 1Ϫ3, intramolecular πϪπ interactions concentration. The model of Bard and Thorp for noncoop-
have been found with the interaction distances in the range erative and nonspecific binding was used.[16] Figure 4 de-
˚
3.29Ϫ3.52 A (see a, b and c in Figure 2). In complexes 1 picts the UV/Vis spectra of complex 1 for a solution buff-
and 2, the intermolecular πϪπ stacking interaction [dis- ered at pH ϭ 7.1 in the presence of increasing quantities of
˚
˚
tance 3.42 A (1) and 3.67 A (2)] results in a single helical CT-DNA. Absorption spectra exhibited an average de-
motif (see a in Figure 3), while CϪH···π, CϪH···SϪC and crease in absorption (hypochromism) of 29% and 42% and
˚
πϪπ stacking (3.39 A) interactions in complex 3 lead to a bathochromic shifts of 7.5 and 6.5 nm for complexes 1 and
double helical network (b in Figure 3).[13]
2, respectively. These observations are consistent with the
Interaction of the complexes with DNA is supported by values reported for other polypyridyl transition metal com-
the results from absorption titration studies with calf thy- plexes.[17,18] Binding constants for complexes 1 and 2 are
mus DNA and inhibition studies (gel electrophoresis) of to- 2.5 ϫ 104 Ϫ1 (s ϭ 0.25) and 2.1 ϫ 104 Ϫ1 (s ϭ 0.21),
poisomerase II of the filarial parasite S. cervi. Chloride salts respectively. The value for s Ͻ 1 is similar to other re-
Figure 3. (a) An intermolecular πϪπ stacking interaction results in a single helical network for complex 1; (b) intermolecular CϪΗ···π,
CϪH···SϪC and πϪπ stacking interactions result in a double helical network for complex 3
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S. Sharma, M. Chandra, D. S. Pandey
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ports.[17] The binding strength of the compounds 1 and 2
to nucleotides is relatively poor. This may be due to the
presence of the bulky EPh3 groups trans to each other,
which causes steric hindrance. Also, the phenyl rings of
EPh3 restrict further the intercalating properties of the com-
plexes. The six-coordinate ruthenium center does not in-
tercalate with the nucleotide and the absorption titration
data supports that tptz is stacking with other tptz ligands
of nearby complexes bound on the surface of the DNA.[17]
Further addition of a 12-fold excess of CT-DNA after satu-
ration of a 13.3 µ solution of complex 1 or addition of a
16-fold excess of CT-DNA to a 40 µ solution of complex
2 caused no changes in the absorption spectra of the final
equilibrium mixtures over a period of 48 h. This indicates a
strong interactive binding mode of (κ3- tptz)RuII complexes.
Figure 5. Inhibition of S. cervi topoisomerase II by complexes 1
and 2; lane 1: pBR322 alone; lane 2: DNA ϩ S. cervi topo II;
lanes 3 and 4 correspond to complex [Ru(κ3-tptz)Cl(PPh3)2]ϩ and
[Ru(κ3-tptz)Cl(AsPh3)2]ϩ (10 µ) and the inhibition percentage is
86% and 93%, respectively
Conclusions
In this work, we have presented the synthesis of the (poly-
pyridyl)RuII complexes [Ru(κ3-tptz)(PPh3)2Cl]ϩ, which have
many potential uses. We have shown that they can be em-
ployed as precursors of other RuII complexes, as metallo-
ligands or as biocatalysts. Detailed studies of the structure,
reactivity and assembling capability of the substituted com-
plexes is in progress in our laboratory.
Experimental Section
General: All reactions were carried out under nitrogen and in de-
aerated solvents. The solvents were of AR grade and were purified
rigorously by standard procedures[19] prior to use. Triply distilled
and deionized water was used for the preparation of the various
buffers. 2,4,6-Tris(2-pyridyl)-1,3,5-triazine (tptz), ammonium tetra-
fluoroborate, ruthenium() chloride hydrate (all Aldrich) and
tetrabutylammonium perchlorate (Fluka) were used as received.
Calf thymus (CT) DNA, supercoiled pBR322 DNA, bovine serum
albumin (BSA), ATP, dithiothreitol (DTT), agarose, ethidium bro-
mide, sodium dodecyl sulfate (SDS) and proteinase were procured
from Sigma Chem. Topoisomersase II from filarial parasite Setaria
cervi was partially purified according to the method by Pandeya et
al.[20] The complex RuCl2(PPh3)3 was prepared by a literature
method.[21]
Figure 4. Absorption spectra of [Ru(κ3-tptz)Cl(PPh3)2]ϩ (13.3 µ),
in buffer A in the presence of an increasing amount of CT DNA
(0Ϫ112 µ); inset represents a plot of (εa Ϫ εf)/(εb Ϫ εf) vs. [DNA]
in µ for [Ru(κ3-tptz)Cl(PPh3)2]ϩ; the best-fit line is superimposed
on the data according to the model of Bard and Thorp[17] for the
absorption titration [Kb ϭ 2.5 ϫ 104 Ϫ1 (s ϭ 0.25)]
Physical Measurements
Spectroscopy and Electrochemistry: Microanalyses were performed
by the microanalytical section of the Sophisticated Analytical In-
strumentation Centre, Central Drug Research Institute, Lucknow.
IR and electronic spectra were recorded with Shimadzu 8201PC
and Shimadzu UV-1601 spectrophotometers, respectively. Elec-
Efficacy of complexes 1 and 2 against DNA topoisomer-
ase II (topo-II) of the filarial parasite S. cervi was exam-
ined. The interaction behavior is supported by the inhibi-
tory effect of the metal complexes on DNA topoisomerase
II of the filarial parasite. Potential antifilarial agents act tronic absorption spectra were measured in a quartz cuvette with
a path length of 1 cm. 1H, 1H-1H COSY, 13C and 31P NMR spectra
either on membrane receptors or on metabolic enzymes.
were recorded with a Bruker DRX-300 NMR instrument. FAB
DNA topoisomerases are cellular enzymes that are intri-
mass spectra were recorded with a JEOL SX 102/DA 6000 mass
cately involved in the topographic structure of DNA tran-
spectrometer using Xenon (6 kV, 10 mA) as the FAB gas. The acce-
scription and mitosis.[18] In general, inhibition depends
lerating voltage was 10 kV and the spectra were recorded at room
upon the availability of binding sites for the enzyme on
temperature with m-nitrobenzyl alcohol as the matrix. Thermal de-
DNA. Topoisomerase has been identified as an important
naturation analyses were conducted with a DU-640 spectrophoto-
biochemical target in chemotherapy and microbial infec-
meter. Electrochemical data were acquired with a PAR model 273A
electrochemistry system at a scan rate of 50 mVsϪ1. The sample
tions. Complexes 1 and 2 are potential inhibitors of DNA
topo-II of the filarial parasite S. cervi with 86% and 93%
inhibition at a 10 µ concentration (Figure 5).
solutions (10Ϫ3 ) were prepared in purified acetonitrile containing
Et4NϩClO4 (0.1 ) as the supporting electrolyte. Solutions were
Ϫ
3560
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 3555Ϫ3563

New Multifunctional Complexes [Ru(κ3-L)(EPh3)2Cl]ϩ
FULL PAPER
deoxygenated by bubbling dinitrogen for about 20 min before each
experiment. The platinum wire working and auxiliary electrodes,
dye. The samples were electrophoresed on 1% agarose gel in tris-
acetate buffer at 20 V for 18 h. Gels were stained with ethidium
and an aqueous saturated calomel reference electrode were used in bromide (0.5 µg/mL) visualized and photographed on a UVP GDS
a three-electrode configuration.
7500 UV trans-illuminator. The percentage relaxation was meas-
ured by micro densitometry of gel using the Gel base/Gel blot Pro
Gel analysis software programme. 1H-NMR and UV/Vis spectral
analyses were used to check the stability of the complexes towards
the solvent (water and DMSO) and no change was observed. Buffer
A (5 m Tris-HCl, pH ϭ 7.1, 50 m NaCl) was used for absorption
titration and buffer B (50 m tris-HCl, pH ϭ 7.5, 50 m KCl) was
used for inhibition studies.
X-ray Crystallography: Suitable crystals for X-ray crystallographic
studies for the complexes 1Ϫ3 were obtained from CH2Cl2/petro-
leum ether (60Ϫ80°C) at room temperature over a period of 3 d.
All the pertinent crystallographic data are recorded in Table 3.
Intensity data were collected at 293(2) K with an EnrafϪNonius
CAD 4 diffractometer using graphite-monochromated Mo-Kα radi-
ation (λ ϭ 0.70930) from plate-like crystals with dimensions 0.22
ϫ 0.22 ϫ 0.17 (1), 0.4 ϫ 0.35 ϫ 0.35 (2) and 0.25 ϫ 0.35 ϫ
0.41 mm (3) in the ω-2θ scan mode in the range from 1.51 to 24.92°.
Intensities of these reflections were measured periodically to moni-
tor crystal decay. The structures were solved by direct methods and
refined by full-matrix least squares on F2 (SHELX-97).[10] In the
final cycles of refinement all the non-H atoms were treated aniso-
tropically. The contribution due to H atoms attached to carbon
atoms was included as a fixed contribution. Final residual values
and goodness-of-fit were R1 ϭ 0.0405, wR2 ϭ 0.1132, GOF ϭ
1.104 (1), R1 ϭ 0.0343, wR2 ϭ 0.0803, GOF ϭ 1.063 (2) and R1 ϭ
0.0673, wR2 ϭ 0.1968, GOF ϭ 1.066 (3). CCDC-229719 (1),
-229720 (2) and -233890 (3) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-1223-336-033; E-mail:
deposit@ccdc.cam.ac.uk].
Preparation of [Ru(κ3-tptz)(PPh3)2]Cl]BF4·H2O (1): Complex 1 was
prepared by either of the following two methods.
Method (a): Hydrated ruthenium trichloride RuCl3·xH2O (0.260 g,
1.0 mmol), dissolved in hot methanol (10 mL), was added to a re-
fluxing solution of triphenylphosphane (PPh3; 1.578 g, 6.0 mmol)
in methanol (50 mL) and the solution was heated under reflux for
1 h. Ligand tptz (0.312 g, 1.0 mmol) was added to the resulting
suspension and the contents of the flask were heated under reflux
for 8Ϫ10 h. After the resulting purple solution was cooled to room
temperature, any solid residue was filtered and the filtrate was con-
centrated under reduced pressure to one fourth of its volume. A
saturated solution of ammonium tetrafluoroborate, dissolved in
methanol, was added to the concentrated solution and the mixture
left for slow crystallization in a refrigerator at 8 °C. The microcrys-
talline product, which slowly deposited, was separated by filtration
and washed repeatedly with methanol and diethyl ether and then
dried in vacuo. Yield 73% (0.786 g). C54H44BClF4N6OP2Ru
(1078.3): calcd. C 60.11, H 4.08, N 7.79; found C 60.08, H 4.12, N
7.74. FAB-MS: m/z obsd. (calcd.), rel. int., [assignm.]: 973 (973),
29, [Ru(κ3-tptz)(PPh3)2Cl]ϩ; 711 (711), 69, [Ru(κ3-tptz)(PPh3)Cl]ϩ;
DNA Binding and Cleavage Studies
DNA Topoisomerase II Estimation: For activity measurements, the
reaction was carried out (10 µL) in a mixture containing buffer B,
10 m MgCl2, 1 m ATP, 0.1 m EDTA, 0.5 m DTT, 30 µg/mL 675 (675), 25, [Ru(κ3-tptz)(PPh3)]ϩ2; 413 (414), 12, [Ru(κ3-tptz)]ϩ2
.
BSA and enzyme protein. The reaction was started by incubation
at 37 °C for 30 min and stopped by addition of 5 µL of loading
1H NMR: δ ϭ 9.12 (d, J ϭ 4.80 Hz, 2 H), 8.92 (d, J ϭ 3.00 Hz),
1 H, 8.74 (d, J ϭ 7.8 Hz, 1 H), 8.57 (d, J ϭ 6.5 Hz, 1 H), 8.12 (t,
Table 3. Crystal data for complexes 1Ϫ3
1
2
3
Empirical formula
Formula mass
Color and habit
Crystal size [mm]
Space group
C54H44BClF4N6OP2Ru
1078.22
purple-black block
0.22 ϫ 0.22 ϫ 0.17
P21/c
C54H44As2BClF4N6ORu
1166.12
violet-black block
0.4 ϫ 0.35 ϫ 0.35
P21/c
C41H43ClN7O2.50PRuS2
905.43
black plate
0.25 ϫ 0.35 ϫ 0.41
F2dd
orthorhombic
System
monoclinic
monoclinic
Unit cell dimensions
˚
a [A]
12.338(3)
24.823(5)
16.291(4)
101.16(2)
2532.4(4)
4
12.439(8)
25.127(3)
16.399(13)
101.27
3753.0(12)
4
13.9940(13)
30.5770(19)
40.295(3)
90.00
17242(2)
16
˚
b [A]
˚
c [A]
˚
β [A]
3
˚
V [A ]
Z
dcalcd. [mg/m3]
1.463
0.502
1.541
1.732
1.395
0.604
µ [mmϪ1
]
Temperature [K]
No.of reflections
No. of refined parameters
R factor all
R factor [I Ͼ 2σ(I)]
wR2
293(2)
7469
639
0.0515
0.0405
0.1132
0.1045
1.104
293(2)
7220
807
0.0496
0.0343
0.0803
0.0727
1.063
293(2)
3157
505
0.0907
0.0673
0.1968
0.1716
1.066
wR2 [I Ͼ 2σ(I)]
Goodness of fit
Eur. J. Inorg. Chem. 2004, 3555Ϫ3563
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3561

S. Sharma, M. Chandra, D. S. Pandey
FULL PAPER
J ϭ 7.5 Hz, 2 H), 8.00 (t, J ϭ 7.8 Hz, 2 H), 7.58 (t, J ϭ 5.1 Hz, 1 (0.334 g). C41H38AsBF4N7Ru (891.6): calcd. C 51.51, H 3.97, N
H), 7.38 (t, J ϭ 6.3 Hz, 2 H) and 7.26Ϫ7.07 (br. m, aromatic pro- 10.26; found C 59.20, H 3.49, N 14.53. FAB- MS: m/z obsd.
tons of PPh3) ppm. 31P{1H} NMR: δ ϭ 16.24 (s) ppm. UV/Vis:
(calcd.), rel. int., [assignm.]: 868 (867), 60, [Ru(κ3-
λmax (ε [dm3 molϪ1cmϪ1])
ϭ
472 (24022), 309(63759), 273 tptz)(AsPh3)(dtc)]ϩ; 562 (561), 100, [Ru(κ3-tptz)(dtc)]ϩ; 413 (414),
1
(149195) nm.
36, Ru(κ3-tptz)]2ϩ. H NMR: δ ϭ 9.26 (d, J ϭ 5.1 Hz, 1 H), 9.05
(d, J ϭ 5.4 Hz, 2 H), 8.94 (t, J ϭ 4.2 Hz, 1 H), 8.80 (dd, J ϭ
Method (b): A suspension of [RuCl2(PPh3)] (0.982 g, 1.0 mmol) in
methanol (50 mL) was treated with tptz (0.312 g, 1.0 mmol) and
the resulting solution was heated under reflux for 8.0 h resulting in
a purple solution. After cooling to room temperature, the resulting
solution was filtered through Celite to remove any solid impurities.
A saturated solution of ammonium tetrafluoroborate, dissolved in
methanol, was added to the filtrate and it was left in the refrigerator
for slow crystallization. After several days, a purple-black crystal-
line product had separated. Analytical and spectroscopic data were
identical to those of the previous method but the yield was higher.
5.4 Hz, 3 H), 8.66 (d), 8.09 (t, J ϭ 7.8 Hz, 4 H) 7.79 (t, J ϭ 6.3 Hz,
2 H) 7.58 (m), 7.17 (m), 6.83 (d, J ϭ 7.1 Hz, 3 H), 4.10 (q, J ϭ
7.2 Hz, 2 H), 3.55 (q, J ϭ 7.2 Hz, 2 H), 1.50 (t, J ϭ 7.2 Hz, 3 H),
1.10 (t,
J ϭ 6.1 Hz, 3
H) ppm. UV/Vis: λmax (ε [dm3
molϪ1cmϪ1]) ϭ 229 (11600), 277 (11500), 343 (2500), 493 (2100)
nm.
Preparation of [Ru(κ3-tptz)(AsPh3)(CN)2] (6): Complex 6 was pre-
pared by the reaction of [Ru(κ3-tptz)(AsPh3)2(Cl)]BF4 (0.583 g,
0.5 mmol) with a slight excess of sodium cyanide according to the
procedure for complex 2. Yield 62% (0.239 g). C38H27AsN8Ru
(771.7): calcd. C 59.14, H 3.50, N 14.52; found C 59.20, H 3.49, N
14.53. FAB-MS: m/z obsd. (calcd.), rel. int., [assignm.]: 745 (745),
43, [Ru(κ3-tptz)(AsPh3)(CN)]ϩ; 719 (720), 35, [Ru(κ3-
tptz)(AsPh3)]2ϩ; 413 (414), 41, [Ru(κ3-tptz)]2ϩ. 1H NMR: δ ϭ 9.21
(d, J ϭ 4.6 Hz, 2 H), 9.05 (d, J ϭ 3.9 Hz, 1 H), 8.79 (d, J ϭ 6.5 Hz,
1 H), 8.43 (t, J ϭ 7.5 Hz, 2 H), 8.25 (m, 4 H), 7.86 (m, 2 H),
7.27 (m), 7.13 (t, J ϭ 5.3 Hz, 2 H) ppm. UV/Vis: λmax (ε [dm3
molϪ1cmϪ1]) ϭ 231 (12786), 320 (11607), 504 (1982) nm.
Preparation of [Ru(κ3-tptz)(AsPh3)2Cl]BF4·H2O (2): This complex
was prepared by a similar method (complex 1) except that AsPh3
(1.836 g, 6.0 mmol) was used in place of PPh3. A violet-black com-
plex was obtained. Yield 71% (0.827 g). C54H44As2BClF4N6ORu
(1166.1): calcd. C 55.57, H 3.77, N 7.20; found C 55.62, H 3.68, N
7.12. FAB-MS: m/z obsd. (calcd.), rel. int., [assignm.]: 1061 (1061),
19,
[Ru(κ3-tptz)(AsPh3)2Cl]ϩ;
755
(755),
54,
[Ru(κ3-
tptz)(AsPh3)Cl]ϩ; 449 (449), 35, Ru(κ3-tptz)Cl]ϩ. 1H NMR: δ ϭ
9.26 (d, J ϭ 5.1 Hz, 2 H), 8.93 (d, J ϭ 3.6 Hz, 1 H), 8.69 (d,, J ϭ
8.1 Hz 1 H), 8.65 (d, J ϭ 7.8 Hz, 1 H), 8.11 (m, J ϭ 7.5 Hz, 4 H),
7.59 (t, J ϭ 5.1 Hz, 1 H), 7.51 (t, J ϭ 6.3 Hz, 2 H) and 7.23Ϫ7.03
(br. m, aromatic protons of AsPh3) ppm. UV/Vis: λmax (ε [dm3
molϪ1cmϪ1]) ϭ 489 (6930), 342 (7250), 271.5 (21355) nm.
Acknowledgments
Thanks are due to the Department of Science and Technology,
Ministry of Science and Technology, New Delhi for providing fin-
ancial assistance [SP/S1/F-04/2000] and the National Single Crystal
X-ray Diffraction Laboratory, Indian Institute of Technology,
Mumbai, for providing single-crystal X-ray data.
Preparation of [Ru(κ3-tptz)(PPh3)(dtc)]Cl (3): Complex 3 was pre-
pared by the reaction of [Ru(κ3-tptz)(PPh3)2Cl]Cl (0.501 g,
0.5 mmol) with sodium diethyldithiocarbamate (0.112 g, 0.5 mmol)
in methanol in the same way as Method (b) for complex 1. Yield
75% (0.322 g). C41H37ClN7PRuS2 (859.4): calcd. C 57.24, H 4.30,
N 11.40; found C 57.46, H 4.17, N 11.21. FAB-MS: m/z obsd.
(calcd.), rel. int., [assignm.]: 824 (823), 100, [Ru(κ3-
tptz)(PPh3)dtc]ϩ; 561 (562), 94, [Ru(κ3-tptz)(dtc)]ϩ; 414 (413), 38,
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Preparation of [Ru(κ3-tptz)(PPh3)(CN)2] (4): Complex 4 was pre-
pared by the reaction of [Ru(κ3-tptz)(PPh3)2(Cl)]BF4 (0.539 g,
0.5 mmol) with a slight excess of sodium cyanide according to the
procedure of Method (b) for complex 1. Yield 63% (0.229 g).
C38H27N8PRu (727.7): calcd. C 62.72, H 3.71, N 15.40; found C
62.69, H 3.65, N 15.38. FAB-MS: m/z obsd. (calcdd), rel. int., [as-
signm.]: 701 (702), 31, [Ru(κ3-tptz)(PPh3)(CN)]ϩ; 675 (676), 33,
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9.04 (d, J ϭ 3.0 Hz, 1 H), 8.92 (d, J ϭ 3.9 Hz, 1 H), 8.71 (d, J ϭ
7.5 Hz, 1 H), 8.63 (t, J ϭ 7.5 Hz, 1 H), 8.16 (m, 4 H), 7.75 (m, 2
H), 7.22 (m), 7.09 (t, J ϭ 5 Hz, 1 H) ppm. 31P{1H} NMR: δ ϭ
32.89 (s) ppm. UV/Vis: λmax (ε [dm3 molϪ1cmϪ1]) ϭ 233 (31663),
247 (35003), 372 (1489), 522 (1722) nm.
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2004, 3555Ϫ3563

New Multifunctional Complexes [Ru(κ3-L)(EPh3)2Cl]ϩ
FULL PAPER
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