The mer-[RuCl3(dppb)(H2O)] complex: A versatile tool for synthesis of RuII compounds

Article abstract of DOI:10.1016/j.poly.2010.09.025

The complex mer-[RuCl₃(dppb)(H₂O)] [dppb = 1,4-bis(diphenylphosphino)butane] was used as a precursor in the synthesis of the complexes tc-[RuCl₂(CO)₂(dppb)], ct-[RuCl ₂(CO)₂(dppb)], cis-[Ru

Full text of DOI:10.1016/j.poly.2010.09.025

Polyhedron 30 (2011) 41–46
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
The mer-[RuCl3(dppb)(H2O)] complex: A versatile tool for synthesis
of RuII compounds
Marilia I.F. Barbosa a, Edjane R. dos Santos a, Angelica E. Graminha a, André L. Bogado b, Leticia R. Teixeira c,
Heloisa Beraldo c, Maria Teresa S. Trevisan d, Javier Ellena e, Eduardo E. Castellano e, Bernardo L. Rodrigues e,
a,
Márcio P. de Araujo f, , Alzir A. Batista
⇑
⇑
a Departamento de Química, Universidade Federal de São Carlos, CP 676, CEP 13565-905, São Carlos (SP), Brazil
b Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, CEP 38302-000, Ituiutaba (MG), Brazil
c Departamento de Química, Universidade Federal de Minas Gerais, CEP 31270-901, Belo Horizonte (MG), Brazil
d Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, CP 12200 60451-970 Fortaleza, Ceará, Brazil
e Instituto de Física, Universidade de São Paulo, CEP 13560-970, São Carlos (SP), Brazil
f Departamento de Química, Universidade Federal do Paraná, Centro Politécnico, CP 19081, CEP 81531-980, Curitiba (PR), Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
The complex mer-[RuCl3(dppb)(H2O)] [dppb = 1,4-bis(diphenylphosphino)butane] was used as a precur-
sor in the synthesis of the complexes tc-[RuCl2(CO)2(dppb)], ct-[RuCl2(CO)2(dppb)], cis-[RuCl2(dppb)(Cl-
bipy)], [RuCl(2Ac4mT)(dppb)] (2Ac4mT = N(4)-meta-tolyl-2-acetylpyridine thiosemicarbazone ion) and
trans-[RuCl2(dppb)(mang)] (mang = mangiferin or 1,3,6,7-tetrahydroxyxanthone-C2-b-D-glucoside)
complexes. For the synthesis of RuII complexes, the RuIII atom in mer-[RuCl3(dppb)(H2O)] may be reduced
by H2(g), forming the intermediate [Ru2Cl4(dppb)2], or by a ligand (such as H2Ac4mT or mangiferin). The
X-ray structures of the cis-[RuCl2(dppb)(Cl-bipy)], tc-[RuCl2(CO)2(dppb)] and [RuCl(2Ac4mT)(dppb)]
complexes were determined.
Received 13 August 2010
Accepted 22 September 2010
Available online 29 September 2010
Keywords:
Ruthenium complexes
Mangiferin
N(4)-meta-tolyl-2-acetylpyridine
thiosemicarbazone
X-ray structures
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
In this study, we made use of the remarkably versatile aqua-
complex mer-[RuCl3(dppb)(H2O)] as the precursor in the synthesis
The ‘‘Ru(P–P)” containing complexes represent an attractive
class of compounds on account of their catalytic activities, and in
this laboratory an ongoing research involves synthesizing new
complexes with this unit [1–9]. The RuIII complex mer-[RuCl3(dppb)
(H2O)] [dppb = 1,4-bis(diphenylphosphino)butane] was synthe-
sized for the first time by our research group at about ten years
ago, and since then it has been used by us in different kinds of reac-
tions [10–13]. The coordinated water can easily be replaced by
monodentate ligands, e.g. N-heterocyclic, forming derivatives with
the general formula [RuCl3(dppb)(L)] [11]. Thus, we have recently
shown that the aqua complex can be used for dehydrogenation
of diamine leading to the formation of RuII diimine complexes
[11,14]. Certainly, this is possible due to the special characteristics
of the aqua-diphosphine complex, which is irreversibly reduced at
low potential (ca. 0.0 V versus Ag/AgCl) to form a mixed-valence
complex [10,11].
of RuII complexes, in which the reducing agents were an external
mediator or the ligand itself, which was, in some cases, coordi-
nated to the metal center in its reduced form. N(4)-meta-tolyl-2-
acetylpyridine thiosemicarbazone and mangiferin were selected
as ligands because of their known potential pharmaceutical prop-
erties [15]. Mangiferin is probably the best studied natural product
extracted from plants of the Anacardiaceae family, the interest in
this compound arises from its pharmacological effects as an antitu-
mor, antiviral and antidiabetic agent. Our main interest in the
preparation of the tc-[RuCl2(CO)2(dppb)], ct-[RuCl2(CO)2(dppb)]
and cis-[RuCl2(dppb)(Cl-bipy)] complexes is to use them as cata-
lysts in the hydrogenation of unsaturated organic substrates, while
the mangiferin complex was selected for its pharmacological
properties.
2. Experimental
2.1. Materials for synthesis
⇑
Corresponding authors.
E-mail addresses: mparaujo@ufpr.br (M.P. de Araujo), daab@ufscar.br (A.A.
The synthetic reactions had to be carried out under an inert
atmosphere (Ar). Solvents were purified by standard methods.
Batista).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.09.025

42
M.I.F. Barbosa et al. / Polyhedron 30 (2011) 41–46
The chemicals employed were of reagent grade quality (Aldrich).
The precursors cis-[RuCl2(P–P)(N–N)] [16], [Ru2Cl4(dppb)3] [17],
[Ru2Cl4(CO)2(dppb)3] [17], [Ru2Cl4(dppb)2] [12], mer-[RuCl3(dppb)
(H2O)] [10] and the N(4)-meta-tolyl-2-acetylpyridine thiosemicar-
bazone [15] ligand were prepared by the literature methods.
Mangiferin (1,3,6,7-tetrahydroxyxanthone-C2-b-D-glucoside) was
extracted from the mango fruit (Mangifera indica L.) in an ethanolic
solution and purified as described in the literature [18].
ORTEP diagrams were prepared with ORTEP-3 for windows [25].
Hydrogen atoms on the aromatic rings were isotropically set, with
a thermal parameter 20% greater than the equivalent isotropic dis-
placement parameter of the atom to which they are bonded. The
data collected and some experimental details are summarized in
Table 1.
2.4. Syntheses
The purity of the mangiferin was checked by elemental analyses
(%C and %H) and UV–Vis spectrum analysis in ethanol solution
(kmax at 366, 316, 260 and 242 nm) [19].
In this paper, the first letter of the prefixes tc and ct in the dicar-
bonyl complexes formulae refers to the position (cis or trans) of the
chlorines to each other, and the second letter refers to the position
of the carbonyls to each other. For non-carbonyl complexes, the cis
and trans refer to the positions of the chlorines to each other.
2.2. Instrumentation
All the NMR spectra were recorded at 293 K, in a BRUKER 9.4 T
spectrometer (400 MHz for hydrogen frequency) at 161.98 MHz,
with CH2Cl2 as solvent (external reference 85% H3PO4), with a cap-
illary containing D2O. Cyclic voltammetry experiments were
carried out in CH2Cl2 solutions containing 0.10 mol Lꢀ1, Bu4NClO4
(TBAP) (Fluka Purum), with a Bioanalytical Systems Inc. BAS-
100B/W electrochemical analyzer; the working and auxiliary
electrodes were stationary Pt foils, and the reference electrode
was Ag/AgCl in a Luggin capillary probe. Under these conditions,
ferrocene is oxidized at 0.43 V (Fc+/Fc).
2.4.1. tc-[RuCl2(CO)2(dppb)]
tc-[RuCl2(CO)2(dppb)] was derived from [Ru2Cl4(dppb)2]
(100 mg, 0.0835 mmol) dissolved in benzene (5 mL) and exposed
to CO gas (1 atm). The mixture was stirred at room temperature,
and after 24 h, the yellow solid formed was filtered off, washed
with diethyl ether and dried under vacuum. Yield: 83.1 mg; 76%.
This complex can also be derived directly from [RuCl3(dppb)(H2O)],
using MeOH/CH2Cl2 as the solvent and an atmosphere of H2(g), as
described previously [12]. In this case, the solution should be ex-
posed to CO(g) and after about 4 h of reaction with hydrogen gas.
Yield: 84.0 mg, 83%. Anal. Calc. (%) for C30H28Cl2O2P2Ru: C, 55.66;
H, 4.31. Found: C, 55.88; H, 4.74%.
The elemental analyses were performed using a FISONS CHNS,
EA 1108 micro analyzer of the Microanalytical Laboratory at Uni-
versidade Federal de São Carlos, São Carlos (SP).
2.4.2. ct-[RuCl2(CO)2(dppb)]
2.3. X-ray crystallography
ct-[RuCl2(CO)2(dppb)] was synthesized from the precursor mer-
[RuCl3(dppb)(H2O)] (100 mg, 0.153 mmol) dissolved in benzene
(5 mL). The red suspension was exposed to CO gas (1 atm) forming
a blue suspension. The mixture was stirred at room temperature,
and after 20 min, the yellow solid formed was filtered off, washed
with diethyl ether and dried under vacuum. Yield: 93.0 mg; 92%.
Anal. Calc. (%) for C30H28Cl2O2P2RuꢁH2O: C, 53.58; H, 4.50. Found:
C, 53.47; H, 4.60%.
Crystals of the complexes were grown by slow evaporation of
dichloromethane/diethyl ether solution. The crystals were
mounted on an Enraf–Nonius Kappa-CCD diffractometer with
graphite-monochromated Mo Ka (k = 0.71073 Å) radiation. The fi-
nal unit cell parameters were based on all reflections. Data were
collected with the COLLECT program [20]; integration and scaling of
the reflections were performed with the HKL DENZO-SCALEPACK system
of programs [21]. Absorption corrections were carried out by the
Gaussian method [22]. The structure was solved by direct methods
with SHELXS-97 [23]. The model was refined by full-matrix least
squares on F2 by means of SHELXL-97 [24]. All hydrogen atoms were
stereochemically positioned and refined with the riding model. The
2.4.3. cis-[RuCl2(dppb)(Cl-bipy)]
cis-[RuCl2(dppb)(Cl-bipy)] was prepared by allowing mer-
[RuCl3(dppb)(H2O)] (100 mg, 0.153 mmol), dissolved in a mixture
of CH2Cl2 (16 mL) and methanol (4 mL), to react with H2(g), at
Table 1
Crystallographic data and refinement details for the complexes cis-[RuCl2(dppb)(Cl-bipy)] (1), tc-[RuCl2(CO)2(dppb)] (2) and
[RuCl(2Ac4mT)(dppb)] (3).
1
2
3
Formula
Formula weight
T (K)
C
38H34Cl4N2P2Ru
C30H28Cl2O2P2Ru
654.43
293(2)
C43H44Cl2N4P2ꢁRuSꢁ0.5H2O
891.80
293(2)
823.48
293(2)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
monoclinic
P21/n
monoclinic
P21/c
15.2296(3)
9.8707(2)
19.5489(4)
94.8560(10)
2928.18(10)
4; 1.484
ꢀ19 ꢂ h ꢂ 19
ꢀ12 ꢂ k ꢂ 12
ꢀ22 ꢂ l ꢂ 24
19409
8356 [Rint = 0.06601]
26.59° (99.7%)
R1 = 0.0431
wR2 = 0.1068
R1 = 0.0589
wR2 = 0.1192
1.018
monoclinic
P21/n
18.7170(8)
10.4900(6)
20.6890(10)
113.318(2)
3730.3(3)
13.9780(4)
20.3360(7)
16.5990(5)
105.095(2)
4555.6(2)
b (°)
V (Å3)
Z, qcalc (mg mꢀ3
Index ranges
)
4; 1.466
4; 1.300
ꢀ22 ꢂ h ꢂ 22
ꢀ11 ꢂ k ꢂ 12
ꢀ24 ꢂ l ꢂ 24
11326
6573 [Rint = 0.0682]
25.0o (99.8%)
R1 = 0.0468
wR2 = .0868
R1 = 0.1248
wR2 = 0.1018
0.901
ꢀ16 ꢂ h ꢂ 16
ꢀ24 ꢂ k ꢂ 22
ꢀ19 ꢂ l ꢂ 19
20865
8084 [Rint = 0.0622]
25.23° (97.7%)
R1 = 0.0584
wR2 = 0.1627
R1 = 0.0787
wR2 = 0.1838
1.051
Reflections collected
Unique reflections/Rint
Completeness to h
Final R indices [I > 2
r
(I)]a,b
R indices (all data)
Goodness-of-fit (GOF)
S

M.I.F. Barbosa et al. / Polyhedron 30 (2011) 41–46
43
1 atm, in a Schlenk flask. The mixture was stirred at room temper-
ature, and after 12 h of reaction, the ligand 4,40-dichloro-2,20-
bipyridine (34.4 mg, 0.153 mmol) was added and the mixture
refluxed for 36 h. The volume of the solution was then reduced
to ca. 2 mL and hexane was added. The solid formed was filtered
off and washed well with diethyl ether. This complex was also pre-
pared as described in the literature, from the precursor
[Ru2Cl4(dppb)3] [26]. Yield: 111 mg; 90%. Anal. Calc. (%) for
C38H34Cl4N2P2Ru: C, 57.35; N, 3.48; H, 4.81. Found: C, 56.99; N,
3.20; H, 4.93%.
2.4.4. [RuCl(2Ac4mT)(dppb)]
The ligand H2Ac4mT (74.0 mg, 0.260 mmol) was added to the
suspension of mer-[RuCl3(dppb)(H2O)] (85.0 mg, 0.130 mmol) in
CH2Cl2 (20 mL) and the mixture was stirred for 2 h at room tem-
perature. The volume of the solution was reduced to ca. 2 mL and
CO
Cl
Cl
P
Ru
CO(g) / CH Cl
2
2
Cl
III
P
Cl
P
CO
Cl
Ru
Ru
P
OH
Cl
2
Cl
P
Cl
Cl
CO
CO
P
P
H (g) / MeOH, CH Cl
Ru
Cl
2
2
2
Ru
P
P
P
CO(g) / CH Cl
2
2
Cl
Scheme 1. Route for synthesis of carbonyl complexes from the precursor the mer-[RuCl3(dppb)(H2O)].
δ
δ
Scheme 2. Metal-assisted oxidative dehydrogenation of mangiferin.

44
M.I.F. Barbosa et al. / Polyhedron 30 (2011) 41–46
diethyl ether was added. The solid formed was filtered off, washed
with diethyl ether and vacuum dried. Yield: Yield: 0.103 g; 89%.
Anal. Calc. (%) for (C42H40ClN4P2RuS)ꢁ1.5CH2Cl2: C, 54.33; H, 4.82;
N, 5.83; S, 3.33. Found: C, 54.72; H, 4.55; N, 6.29; S, 3.03%.
The mother liquor was dried, and its infrared spectrum showed
The reaction of the mer-[RuCl3(dppb)(H2O)] complex with
mangiferin involves the dehydrogenation of this ligand as in
Scheme 2, which is similar to the scheme suggested for the dehy-
drogenation of the o-phenylediamine ligand [14].
Moreover, intermediate 2 is oxidized very fast, since it was not
detected in a 31P{1H} NMR experiment carried out immediately
after the reagents were mixed.
a
mSO band at 1080 cmꢀ1
.
This reaction was also attempted with an equimolar mixture of
precursor and ligand and in this case the yield fell to about 45%.
The complex [RuCl(2Ac4mT)(dppb)] was also obtained from
[RuCl2(dppb)(PPh3)], using a 1:1 M ratio of complex:ligand. The
yield obtained by this method was equal to that in the first
method, 89%.
H2Ac4mT can be oxidized to a sulfoxide or sulfone. Thus, in the
reaction of the aqua complex with this ligand, in excess, part of the
ligand may be oxidized, consequently reducing the RuIII to RuII and
forming [RuCl(2Ac4mT)(dppb)] (the mSO band of the oxidized li-
gand was detected in the IR spectrum of the solid obtained from
mother liquor, as mentioned in the Section 2).
To confirm the above suggested mechanism an electrochemical
experiment was done. A mixture of the mangiferin and 2,20-bipyr-
idine ligands (in the proportion 1:1) was dissolved in dichloro-
methane, and mer-[RuCl3(dppb)(H2O)] was added, the reaction
was followed by cyclic voltammetry. Thus, in the first cycle, per-
formed immediately after the reagents were mixed, the voltammo-
gram showed two oxidation processes: one at 420 mV and another,
at 700 mV (Fig. 1). The first oxidation peak associated to the pres-
ence of the trans-[RuCl2(bipy)(dppb)] complex, and the second is
associated with the trans-[RuCl2(dppb)(mang)] complex [16]. The
solution used in the electrochemical experiment was concen-
trated; 31P{1H} NMR was recorded, and a peak at 33.0 ppm con-
firms the formation of trans-[RuCl2(bipy)(dppb)] [16]. Obviously,
this was possible because the ‘‘RuCl2(dppb)” (formed in the reac-
tion of the aqua complex with the mangiferin, which reduces the
original ruthenium(III) complex in solution) reacts with 2,20-bipyr-
idine. The formation of trans-[RuCl2(bipy)(dppb)] is in agreement
with the previously published work, in which the reaction of
mer-[RuCl3(dppb)(H2O)] with o-phenylenediamine (opda) (1:1)
yielded two different ruthenium(II) complexes, one with the ligand
o-phenylenediamine, trans-[RuCl2(dppb)(opda)] and another with
o-benzoquinonediimine (bdqi) – the two-electron oxidation prod-
uct of opda, trans-[RuCl2(dppb)(bqdi)]. With this in mind, it is not
expected the formation of ruthenium(III) complexes in this type of
reaction. This is confirmed by 31P NMR and EPR analysis [14].
Also, immediately after the mixture of the reagents, the 31P{1H}
NMR spectrum showed two signals, virtually with the same inten-
sity: one at 33.0 ppm and another, at 56.9 ppm, the first attributed
to the trans-[RuCl2(dppb)(bipy)] and the second, to the trans-
[RuCl2(dppb)(mang)] complex.
2.4.5. trans-[RuCl2(dppb)(mang)]
The complex trans-[RuCl2(dppb)(mang)] was obtained by allow-
ing mer-[RuCl3(dppb)(H2O)] (100 mg, 0.154 mmol), dissolved in
methanol (50 mL), to react with mangiferin (650 mg, 0.154 mmol).
After 6 h, the solid obtained was filtered off, washed with methanol
and vacuum dried. Yield: 0.110 g; 71%. Anal. Calc. (%) for
C47H44Cl2O11P2Ru: C, 55.41; H, 4.35. Found: C, 55.53; H, 4.41%.
3. Results and discussion
The synthetic routes used here to obtain the carbonyl com-
plexes can be seen in Scheme 1.
It is well known [27] that the H2Ac4mT ligand can be found in
two possible forms (Fig. 2):
As will be discussed below, in the [RuCl(2Ac4mT)(dppb)] com-
plex this ligand is in the thiol form.
The 31P{1H} NMR spectra of trans-[RuCl2(dppb)(mang)], tc-
[RuCl2(CO)2(dppb)] and ct-[RuCl2(CO)2(dppb)] show singlets at
56.9, 8.6, and 11.0 ppm, respectively.
Fig. 1. Cyclic voltammogram of products of the reaction of the mer-
[RuCl3(dppb)H2O] complex with mangiferin in presence of 2,20-bipyridine (1:1),
in CH2Cl2 (Pt versus AgCl, 0.1 M TBAP.
+
(A)
(B)
H3C
H3C
CH3
H
CH3
HN
N
N
HN
N
N
S
P
N
S
P
N
Ru
P
Ru
P
Cl
Cl
Fig. 2. Two possible forms of coordination of the ligand N(4)-meta-tolyl-2-acetylpyridine thiosemicarbazone to the metal center: (A) uncharged, thione form or (B) anionic
(deprotonated, charged), thiol form.

M.I.F. Barbosa et al. / Polyhedron 30 (2011) 41–46
45
FTIR was used to distinguish between the ct- and tc-[RuCl2
(CO)2(dppb)] isomers. Thus, the IR spectrum of the ct-isomer
shows just one mCO band at 2079 cmꢀ1, while the tc-isomer shows
two m
CO bands (2008 cmꢀ1 and 2065 cmꢀ1), in agreement with the
trans and cis positions of CO for ct- and tc-[RuCl2(CO)2(dppb)],
respectively.
6
Fig. 3. ORTEP view of the complexes: (1) cis-[RuCl2(dppb)(Cl-bipy], (2) tc-[RuCl2(CO)2(dppb)] and (3) [RuCl(2Ac4mT)(dppb)] showing the atom labeling and the 50%
probability ellipsoids.
Table 2
Selected bond lengths (Å) and angles (°) for cis-[RuCl2(dppb)(Cl-bipy)] (1), tc-[RuCl2(CO)2(dppb)] (2) and [RuCl(2Ac4mT)(dppb)] (3).
cis-[RuCl2(dppb)(Cl-bipy)]
tc-[RuCl2(CO)2(dppb)]
[RuCl(2Ac4mT)(dppb)]
Bond
Bond
Length (Å)
Bonds
Length (Å)
Length (Å)
Ru(1)–Cl(1)
Ru(1)–Cl(2)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–N(1)
Cl(18)–C(18)
P(2)–C(4)
2.4156(12)
2.4777(12)
2.3047(12)
2.3382(12)
2.121(3)
Ru–Cl(1)
Ru–Cl(2)
Ru–P(1)
2.411(8)
2.412(8)
2.424(7)
2.449(7)
1.923(4)
1.118(4)
1.128(4)
Ru–Cl(1)
Ru–S(1)
Ru–P(1)
Ru–P(2)
Ru–N(1)
S(1)–C(8)
N(2)–N(3)
2.4597(13)
2.3479(13)
2.3315(11)
2.3073(11)
2.125(4)
Ru–P(2)
Ru–C(50)
C(60)–O(1)
C(50)–O(2)
1.727(4)
1.834(5)
1.697(5)
1.355(6)
Angle (°)
Angle (°)
177.2(3)
92.47(2)
88.80(10)
177.61(12)
177.21(10)
88.37(10)
88.60(3)
Angle (°)
N(2)–Ru(1)–P(1)
N(1)–Ru(1)–P(1)
N(2)–Ru(1)–P(2)
N(1)–Ru(1)–P(2)
P(1)–Ru(1)–P(2)
N(2)–Ru(1)–Cl(1)
N(1)–Ru(1)–Cl(1)
P(1)–Ru(1)–Cl(2)
96.31(10)
90.14(10)
104.37(10)
175.84(11)
93.61(4)
166.95(10)
90.49(11)
175.84(4)
O(2)–C(50)–Ru(1)
P(1)–Ru(1)–P(2)
C(50)–Ru(1)–P(2)
C(50)–Ru(1)–P(1)
C(60)–Ru(1)–P(2)
C(60)–Ru(1)–P(1)
Cl(1)–Ru(1)–P(2)
C(60)–Ru(1)–Cl(2)
N(2)–Ru–P(2)
N(1)–Ru–P(2)
N(2)–Ru–P(1)
N(1)–Ru–P(1)
P(1)–Ru–P(2)
N(2)–Ru–S
91.48(11)
96.41 (10)
173.58(11)
104.31(10)
94.70(4)
83.20(12)
159.49(10)
174.17(4)
N(1)–Ru–S
P(2)–Ru–Cl(1)
90.88(10)

46
M.I.F. Barbosa et al. / Polyhedron 30 (2011) 41–46
In the 31P{1H} NMR spectra of cis-[RuCl2(dppb)(Cl-bipy)] and
Appendix A. Supplementary data
[RuCl(2Ac4mT)(dppb)] there are doublets, at 43.8 and 30.4 ppm
(2JP–P = 31.6 Hz), and 42.6 (P1) and 32.9 (P2) ppm (2JP–P = 33.9 Hz),
respectively. The presence of doublets, clearly exclude the coordi-
nation of HAc4mTꢀ to the metal center through two nitrogen
atoms [28].
The X-ray structures of the cis-[RuCl2(dppb)(Cl-bipy)], tc-
[RuCl2(CO)2(dppb)] and [RuCl(2Ac4mT)(dppb)] complexes are
shown in Fig. 3, and the relevant bond lengths and angles are sum-
marized in Table 2.
CCDC 746.020, 746.021 and 746.022 contains the supplemen-
tary crystallographic data for cis-[RuCl2(dppb)(Cl-bipy)], tc-
[RuCl2(CO)2(dppb)] and [RuCl(2Ac4mT)(dppb)]. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.
In cis-[RuCl2(dppb)(Cl-bipy)], the Ru–Cl bond length is longer
when the chlorine is trans to the phosphorus atom than trans to
the nitrogen atom (2.4777(12) Å and 2.4156(12) Å, respectively),
since the trans influence of the phosphorus atom is stronger than
that of the nitrogen atom.
In [RuCl(2Ac4mT)(dppb)], the Ru–Cl bond length, 2.4597(13) Å
is closer to the value observed for Ru–Cl trans to the phosphorus
atoms in cis-[RuCl2(dppb)(Cl-bipy)], since it is also trans to a phos-
phorus atom.
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In the complex tc-[RuCl2(CO)2(dppb)], the bond lengths Ru–P
are longer than in the other complexes [2.424(7) Å and
2.449(7) Å], owing to the competitive effect between two good
p-acceptor ligands (phosphorus atom and CO) [29].
In the complex [RuCl(2Ac4mT)(dppb)], the bond lengths
1.697(5) Å and 1.355(6) Å are typical for C–S and N–N single bonds,
respectively [30]. The distance Ru–S, 2.3479(13) Å is also in the
normal range [30]. In this complex, the distance Ru–N(1) is longer
than the distance Ru–N(2) [2.125(4) Å and 2.046(3) Å, respec-
tively], in this case, the N(2) is trans to a phosphorus atom, which
is a good
p
acceptor species, and N(1) is trans to the Sꢀ, a good do-
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173.58(11)°, while the angle N(1)–Ru–S is only 159.49(10)°, far
from 180°.
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Polyhedron 22 (2003) 3205.
mer-[RuCl3(dppb)(H2O)] has proved to be a extremely versatile
precursor for the synthesis of different kinds of RuII complexes. In
this study, it was used to obtain a ruthenium(II) complex contain-
ing the m-tolyl-2-acetylpyridine-thiosemicarbazone ion as a li-
gand. Also, the mer-[RuCl3(dppb)(H2O)] complex, in the presence
of a reducing agent, was used to prepare new carbonylrutheni-
um(II) complexes. The oxidizing property of this aqua complex al-
lowed us to stabilize the compound trans-[RuCl2(dppb)(mang)],
containing the natural pharmaceutical product, mangiferin. The
mechanism of the reaction between the mangiferin and mer-
[RuCl3(dppb)(H2O)] was elucidated by cyclic voltammetry and
pulse differential voltammetry, as well as by 31P{1H} experiments.
[28] E.M.A. Valle, F.B. do Nascimento, A.G. Ferreira, A.A. Batista, M.C.R. Monteiro,
S.P. Machado, J. Ellena, E.E. Castellano, E.R. de Azevedo, Quim. Nova 31 (2008)
807.
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Castellano, C.L. Donnici, J.V. Comasseto, A.A. Batista, Organometallics 24
(2005) 6159.
[30] C. Rodrigues, A.A. Batista, R.Q. Aucélio, L.R. Teixeira, L.do.C. Visentin,, H.
Beraldo, Polyhedron 27 (2008) 3061.
Acknowledgement
We thank FAPESP, CNPq, CAPES for the financial support and
Johnson Matthey plc for the loan of RuCl3 (to M.P.A).