Ruthenium complexes of the scorpionate ligand bis(3,5-dimethylpyrazol-1-yl) -dithioacetate and the effect of nitric oxide coordination

Article abstract of DOI:10.1002/ejic.200401062

Six new ruthenium(II) complexes with the scorpionate ligand bis(3,5-dimethylpyrazol-1-yl)dithio-κ³N,N,S-acetate (bdmpzdta) were obtained by treatment of the ligand with RuCl₃ or [RuCl ₃(NO)] in 1:1 or 2:1 molar ratios in the presence or absence of ethylenediamine. In all six complexes the pyrazolic rings lie in the equatorial plane. The mononitrosyl complexes present a sharp ν(NO) band in the range 1864-1859 cm^-1 for samples prepared either as KBr tablets or dichloromethane solutions. In the case of [Ru(NO)-(bdmpzdta)₂]Cl (7), the dithiocarboxylate group of one of the ligands is not coordinated (κ²N,N). In the other five complexes, however, bdmpzdta behaves as a κ³N,N,S scorpionate ligand. When the complexes obtained from RuCl₃ were dissolved in dichloromethane and NO was bubbled through the solution, a high degree of coordination of NO⁺ was observed, according to IR, UV and voltammetric studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200401062

FULL PAPER
Ruthenium Complexes of the Scorpionate Ligand Bis(3,5-dimethylpyrazol-1-yl)-
dithioacetate and the Effect of Nitric Oxide Coordination
Mayreli Ortiz,[a] Ariadna Penabad,[a] Alicia Díaz,[a] Roberto Cao,*[a] Antonio Otero,[b]
Antonio Antiñolo,[b] and Agustín Lara[b]
Keywords: N ligands / Nitric oxide / Ruthenium / S ligands / Scorpionate ligands
Six new ruthenium(II
)
complexes with the scorpionate
(bdmpzdta)2]Cl (7), the dithiocarboxylate group of one of the
ligands is not coordinated (κ2N,N). In the other five com-
plexes, however, bdmpzdta behaves as a κ3N,N,S scorpi-
onate ligand. When the complexes obtained from RuCl3 were
dissolved in dichloromethane and NO was bubbled through
the solution, a high degree of coordination of NO+ was ob-
served, according to IR, UV and voltammetric studies.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
ligand bis(3,5-dimethylpyrazol-1-yl)dithio-κ3N,N,S-acetate
(bdmpzdta) were obtained by treatment of the ligand with
RuCl3 or [RuCl3(NO)] in 1:1 or 2:1 molar ratios in the pres-
ence or absence of ethylenediamine. In all six complexes the
pyrazolic rings lie in the equatorial plane. The mononitrosyl
complexes present a sharp ν(NO) band in the range 1864–
1859 cm–1 for samples prepared either as KBr tablets or
dichloromethane solutions. In the case of [Ru(NO)-
κ3N,N,O scorpionates, but with a weak interaction through
the oxyanionic moiety. Mononitrosyl complexes of RuII
were also obtained from the same ligands with NO coordi-
nated in the apical position.[7] NO was found to have a
strong trans influence on the oxyanionic moiety. As a conse-
quence, the mononitrosyl bis(bis-pyrazolic) complexes of
RuII show an on/off switching process of the oxyanionic
moiety trans to the coordinated NO.
Introduction
The physiological functions of nitric oxide (NO) have
been widely studied in the past decade as dysfunction in
NO metabolism has been associated with a great number
of diseases.[1,2] When a patient has a severe infection, as in
so-called septic shock, the body generates such a large
amount of nitric oxide that the patient’s blood pressure
practically collapses. A specific inhibitor for induced nitric
oxide synthase, iNOS, has yet to be found. An alternative
to save patients’ lives in cases of septic shock involves find-
ing NO scavengers that can be used when NO is produced
in relatively large amounts.
We report here the main results obtained on RuII com-
plexes with a similar ligand: bis(3,5-dimethylpyrazol-1-yl)-
dithioacetate (bdmpzdta; 1), which is depicted in Figure 1.
This ligand is expected to behave as a κ3N,N,S scorpionate,
but with a softer anionic moiety. For this reason, a higher
scorpionate affinity for RuII than the previously studied
bdmpza and bdmpzsa ligands is to be expected.
RuIII complexes are known to coordinate NO to form
stable RuII mononitrosyl complexes and these can therefore
act as efficient NO scavengers. A number of different RuIII
complexes with polyaminocarboxylic acids have been
studied as NO scavengers.[3–5]
Recently, we reported different ruthenium(ii) complexes
with the bis(3,5-dimethylpyrazol-1-yl)methane derivatives
bis(3,5-dimethylpyrazol-1-yl)methanesulfonate (bdmpzsa)
and bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza).[6,7]
Both ligands lie in the equatorial plane and coordinate as
[a] Laboratorio de Bioinorgánica, Facultad de Química, Uni-
versidad de La Habana,
Figure 1. Schematic representation of ligand 1.
La Habana 10400, Cuba
Fax: +537-873-3502
E-mail: cao@fq.uh.cu
[b] Departamento de Química Inorgánica, Orgánica y Bioquímica,
Facultad de Ciencias Químicas, Universidad de Castilla-La
Mancha,
Results and Discussion
In a previous paper,[6] we reported a kinetic study of the
interaction of RuCl3 with bis(3,5-dimethylpyrazol-1-yl)ace-
13071 Ciudad Real, Spain
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2005, 3135–3140
DOI: 10.1002/ejic.200401062
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M. Ortiz, A. Penabad, A. Díaz, R. Cao, A. Otero, A. Antiñolo, A. Lara
FULL PAPER
tate (bdmpza; k = 1.1×10–3 s–1), and bis(3,5-dimethylpyr- in the MLCT band, pseudo first-order rate constants of k
azol-1-yl)methanesulfonate (bdmpzsa; k = 1.6×10–3 s–1), in = 1.2×10–4 s–1 and 3.4×10–4 s–1 were obtained for 1:1 and
a 1:1 molar ratio in methanol. Coordination of the ligand 1:2 RuIII:bdmpzdta molar ratios, respectively. Both values
involves the reduction of RuIII to RuII. We assumed that are ten times smaller than those reported previously for
the reducing agent was methanol, but could not detect the similar ligands (bdmpza and bdmpzsa).[6] Furthermore,
corresponding oxidation product. After this study was pub- with these latter ligands the rate constants for 1:2 molar
lished, a signal at δ = 9.2–9.4 ppm, corresponding to me- ratios could not be detected using the same procedure.
thanal, was detected in the 1H NMR spectra when the reac-
tion was carried out in an NMR tube.
The complete reduction of RuIII was confirmed by EPR
spectroscopy − all the complexes are silent. As one would
The interaction of RuCl3 with bis(3,5-dimethylpyrazol-1- expect, all NMR spectra contained sharp signals.
yl)dithioacetate (bdmpzdta; 1) was studied spectrophoto- The interaction of ligand 1 with RuCl3 gave the com-
metrically in methanol in an effort to confirm the reduction plexes [{Ru(H2O)(bdmpzdta)(Cl)}]2 (2), [Ru(bdmpzdta)-
of RuIII, as observed previously with similar ligands. A de- (en)Cl] (3) and [Ru(bdmpzdta)2] (4) using procedures sim-
crease in the absorbance of the bdmpzdta band at 350 nm ilar to those reported for bdmpza and bdmpzsa.[6] Similarly,
and the appearance and increase in the absorbance of the [RuNO(bdmpzdta)(Cl)2] (5), [RuNO(bdmpzdta)(en)]Cl2 (6)
MLCT band at approximately 300 nm were observed (see and [RuNO(bdmpzdta)2]Cl (7) were synthesised by the in-
Figure 2).
teraction of 1 with [RuCl3(NO)].
1
The H and 13C NMR spectra of 2, 3, 4, 5 and 6 gave
only one set of signals for the pyrazolic rings and ethyl-
enediamine (3, 6). In the case of compound 7 (Figure 3)
this statement is not completely accurate since the signals
of some of the atoms show a slight (or moderate) splitting.
The observed equivalence in the NMR signals indicates that
the pyrazolic rings of ligand 1 lie in the equatorial plane, as
does the ethylenediamine unit in complexes 3 and 6 (Fig-
ure 3).
The composition and low solubility of complex 2 in po-
lar organic solvents suggests a dimeric form in which the
two chloride ions in the equatorial plane form bridges be-
tween the two RuII centres (Figure 3), similar to a pre-
viously reported structure.[8] Under such conditions, and
with the water molecule (from RuCl3·xH2O) at the apical
position trans to the coordinated dithiocarboxylate group,
the two pyrazolic rings remain equivalent. Each of the two
chloride anions in the equatorial plane of compound 5 is
coordinated to one RuII (Figure 3) and the octahedral
structure is achieved without the need for bridge formation.
Figure 2. Variations in the UV/Visible spectra with time for the
interaction of RuCl3 with bdmpzdta (1:1 molar ratio) in methanol.
This MLCT band corresponds to the transition from
RuII to 1. A signal at δ = 9.35 ppm (due to methanal) was
detected in the 1H NMR spectra when the reaction was
carried out in an NMR tube. From the variations observed
Figure 3. Schematic representation of the synthesised complexes 2–7.
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Eur. J. Inorg. Chem. 2005, 3135–3140

Ruthenium Complexes with a Scorpionate Ligand
FULL PAPER
As expected, the dithiocarboxylate group (a soft base) is cant for the aliphatic CH signal (Figure 4). The signal at δ
very strongly coordinated at an apical position to RuII (soft = 70.3 ppm was assigned to the CH aliphatic group bound
–
acid) through a sulfur atom (Figure 3). Evidence for this to the coordinated CS2 , while the signal at δ = 83.4 ppm
–
structure is provided by the significant shift to higher field corresponds to the free CS2 .
of the CS2– and aliphatic CH signals in the 13C NMR spec-
tra. Moreover, a significant shift in the νC=S and νC–S
stretching bands is observed with respect to the IR spec-
–
trum of the free ligand. Coordination of the CS2 moiety
to RuII is appreciably stronger than that observed for the
–
–
CO2 moiety of bdmpza and the SO3 moiety of bdmpzsa,
as reported previously.[6,7,9] Consequently, ligand 1 behaves
as a κ3N,N,S scorpionate ligand.
The strong coordination of the CS2– moiety should cause
a slight distortion of the two pyrazolic rings in 1. This dis-
tortion takes the rings out of the equatorial plane, although
the effect is the same for both rings. This could be the
reason why only one set of signals is observed even in the
presence of this distortion. In this sense, it is interesting to
point out that Otero et al. have investigated TiIV-bdmpzdta
complexes and reported a distortion in the planarity of the
Figure 4. 13C NMR spectra of ligand 1 (inset) and complex 7 in
CD3OD.
–
pyrazolic rings.[10] In this latter case the soft CS2 moiety
was coordinated to a hard acid (TiIV).
The interaction of ligand 1 with RuII should initially pass
In the nitrosyl complexes [Ru(NO)(L)2]Cl (where L =
through the coordination mode κ2N,N. The coordination of bdmpza or bdmpzsa), a dynamic on/off switching exchange
the CSS– group should require additional energy and time between the two oxyanionic groups was found to take place
in order to achieve the formation of the stable RuII–S bond. in the coordination to RuII at the only remaining vacant
This process involves a distortion in the equatorial plane position (trans to NO).[7] This process is favoured by the
of the pyrazolic rings. Such a situation could explain the powerful NO trans influence over the oxyanionic moiety. In
kinetically slow coordination of ligand 1 (ten times slower contrast, such an exchange was not observed in complex 7
than for bdmpza and bdmpzsa).[6]
and the only RuII–S bond formed was not dissociated by
The coordination of NO in compounds 5, 6 and 7 was NO in the trans position.
fully characterised by IR spectroscopy. A sharp and intense
The trans influence of NO on the dithiocarboxylate
band is observed at around 1860 cm–1 for all the mononi- group is evidenced by the marked shift observed (about
trosyl complexes, whether the samples were prepared as 20 ppm) in the 13C NMR signal relative to that in the corre-
KBr tablets or CH2Cl2 solutions. This band was assigned sponding NO-free complex. It appears that the ionic char-
to the ν(NO) stretching vibration and indicates that in these acter of this bond is increased when coordinated NO weak-
complexes NO is coordinated in a linear mode, as a ens the RuII–S bond and increases the positive charge on
{RuNO}6 unit according to the Enemark–Feltham formal- the metal. In this way, the coordinated sulfur atom could
ism.[11] As expected, these ν(NO) values are lower than that increase its electron density with the consequent shielding
for the [RuCl3(NO)] starting material.
of the CS2 carbon atom. The coordination of NO appears
A single set of signals was observed for ligand 1 in the to cause a strong electronic shift along the S–RuII–NO axis,
NMR spectra of compounds 5 and 6, indicating that in the which is also seen in the MLCT band as a hypsochromic
nitrosyl complexes NO is coordinated at the apical position shift (by about 10 nm). This change is observed in the UV/
trans to the bonded dithiocarboxylate moiety. It is worth Vis spectra when comparing compounds 2, 3 and 4 with
pointing out that a single set of signals was also observed the corresponding mononitrosyl complexes 5, 6 and 7,
for ethylenediamine in compound 6.
respectively. The mononitrosyl complexes (5, 6 and 7) do
An interesting situation was found for [Ru(bdmpzdta)2- not liberate NO under a strong vacuum and in compound
–
NO]Cl (7) as the 13C NMR spectrum (Figure 4) contains 7 the second CS2 moiety does not substitute NO. These
–
two signals for the CS2 group (δ = 211.0 and 243.2 ppm). observations demonstrate the high stability of the RuII–NO
–
The latter value corresponds to the free CS2 group that bond. Taking this into consideration, we decided to study
does not replace NO. In this complex one bdmpzdta is the possible interaction of compounds 2, 3 and 4 with NO
therefore coordinated as a bidentate ligand (κ2N,N) and the in an attempt to obtain the corresponding complexes with
other as a κ3N,N,S scorpionate ligand. The difference be- coordinated NO+ ligand. In order to achieve this aim, NO
tween the two coordinated ligands in compound 7 is that was bubbled through dichloromethane solutions of these
the bidentate one is not distorted from the equatorial plane, complexes under an oxygen-free inert atmosphere. The
while the scorpionate κ3N,N,S ligand should be. This ar- solutions, which were initially brown, became reddish after
rangement explains the observed splitting of the signals in 15–20 min. These compounds were isolated and character-
the NMR spectra of 7, an effect that is particularly signifi- ised by UV/Vis and IR spectroscopy. The UV/Vis spectra
Eur. J. Inorg. Chem. 2005, 3135–3140
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M. Ortiz, A. Penabad, A. Díaz, R. Cao, A. Otero, A. Antiñolo, A. Lara
Table 1. Spectroscopic properties of the compounds obtained after bubbling NO through CH2Cl2 solutions of 2–4.
FULL PAPER
Compounds
IR (ν, cm–1)
ν(C=S)
UV (λ, nm)
˜
ν(NO)
ν(C–S)
[{Ru(bdmpzdta)(Cl)(H2O)}]2 (2) + NO(g)
[Ru(bdmpzdta)(Cl)(en)] (3) + NO(g)
[Ru(bdmpzdta)2] (4) + NO(g)
1866
1862
1857
1028
1032
1034
784
782
786
286
290
292
are very similar (Table 1) to those of complexes obtained compounds obtained by bubbling NO through solutions of
from [RuCl3(NO)] (compounds 5, 6 and 7). A strong sharp complexes 2–4 show very similar characteristics (Table 1) to
band is observed in the IR spectra of these complexes at those found for compounds 5–7, respectively, and should
around 1860 cm–1 and this is assigned to ν(NO). This band therefore be considered as equivalent. This fact should be
was seen when the samples were prepared either as KBr attributed to the coordination of NO+ by the bubbled com-
tablets or CH2Cl2 solutions (Figure 5 for complex 3 with plexes that is assumed to be present in this type of solu-
NO bubbled through). The positions of the ν(NO) bands tion.[12]
are very similar to those in 5, 6 and 7, respectively, as de-
DMSO solutions of the compounds obtained by bub-
picted in Figure 5 for compound 3 (after NO bubbled bling NO through solutions of complexes 2, 3 and 4 in
through) and mononitrosyl complex 6.
dichloromethane were studied by voltammetry. The results
of these experiments were also similar to those found for
compounds 5, 6 and 7, respectively. The irreversible cath-
odic wave assigned to the RuII–NO+ + e– Ǟ RuII–NO0 re-
duction[13] is observed in the voltammograms of these six
complexes between –700 and –720 mV, as depicted in Fig-
ure 6 for complexes 5 and (2 + NO).
Figure 5. IR spectra of a) compound 3, b) compound 3 with NO
bubbled through and c) compound 6.
The areas of the ν(NO) bands of the compounds after
bubbling NO through were compared with those obtained
from [RuCl3(NO)], with the ν(C=S) and ν(C–S) stretching
bands taken as references. The areas of the ν(NO) bands of
the former compounds correspond to 75–90% of those of
the latter. This indicates that a high percentage of RuII co-
ordinates NO. Possible explanations for the incomplete co-
ordination of NO include unavoidable partial oxidation of Figure 6. Cyclic voltammograms of complexes 5 (---) and (2 + NO)
(
___).
NO and its relatively low solubility in CH2Cl2. The fact that
100% NO coordination was not achieved in any of these
compounds means that they are not pure. Purification of
the nitrosyl compound by bubbling NO through solutions
of the complexes was not successful.
Although the interaction of complexes 2, 3 and 4 with
NO was studied in dichloromethane, it is reasonable to con-
sider the possibility that they could behave as NO scaven-
gers in a biological system. This possibility is currently un-
der investigation.
The 1H NMR spectra gave an overlap of signals that was
not possible to interpret. The 13C NMR spectra of the com-
pounds obtained after bubbling NO through show a double
set of signals that are not well resolved in most cases. A
well-defined 13C NMR spectrum was obtained only for the
product of bubbling NO through a solution of complex 2
(Supporting Information, Figure S1). The differences be-
Conclusions
The interaction of RuCl3 with bis(3,5-dimethylpyrazol-
tween the chemical shifts of both set of signals, one of 1-yl)dithioacetate (bdmpzdta; 1) in methanol leads to the
which is much more intense than the other, mainly lie in reduction of RuIII to RuII with the stabilisation of the latter
the range 0.1–1.1 ppm. For the CSS– signal the observed species. Reaction of compound 1 with [RuCl3(NO)] gives
difference was about 20 ppm. The set of signals with highest new, stable nitrosyl complexes. In all six complexes the pyr-
intensity is very similar to that of the spectra of the com- azolic rings of ligand 1 lie in the equatorial plane with the
–
pounds obtained from [RuCl3(NO)] (5–7), whereas the CS2 group also coordinated. The ligand therefore behaves
other set of signals is similar to that of the spectra of the as a κ3N,N,S scorpionate system. One exception to this
corresponding NO-free complexes (2–4). Evidently, the trend was observed in complex 7, where the second ligand
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Eur. J. Inorg. Chem. 2005, 3135–3140

Ruthenium Complexes with a Scorpionate Ligand
FULL PAPER
is coordinated in a κ2N,N manner with its dithiocarboxylate
moiety free.
ane, and the LiCl filtered off. The solvent was removed from the
filtrate under vacuum to give a brown, hygroscopic solid. Yield:
0.166 g (80%). C12H17ClN4ORuS2 (433.7): calcd. C 33.21, H 3.92,
When NO was bubbled through solutions of complexes
2, 3 and 4 in dichloromethane, a high level of coordination
of NO+ took place to give compounds that are apparently
equivalent to complexes 5, 6 and 7, respectively. For exam-
ple, the ν(NO) band of the latter lies in the range 1864–
1859 cm–1, while for the former complex the band appears
at 1866–1857 cm–1. The irreversible voltammetric wave cor-
responding to the RuII–NO+ + e– Ǟ RuII–NO° reduction
is observed in the same range (–700 and –720 mV) for both
sets of compounds.
N 12.92; found C 33.23, H 3.94, N 12.90. IR (KBr): ν = 1562
˜
ν(C=N), 1027 νas(C=S), 791 cm–1 νs(C–S). UV/Vis: λ (log ε) =
1
295 nm (3.36, MLCT). H NMR (250 MHz, CD3OD, 298 K): δ =
2.12 (s, 6 H, Me3), 2.40 (s, 6 H, Me5), 5.95 (s, 2 H, H4), 7.34 (s,
1 H, CH) ppm. 13C{1H} NMR/DEPT-135 (62.89 MHz, CD3OD,
298 K): δ = 12.4 (+, Me5), 13.8 (+, Me3), 76.4 (+, CH), 105.1 (+,
C4), 143.2 (0, C5), 152.5 (0, C3), 240.5 (0, CS2 ) ppm.
–
[Ru(bdmpzdta)(Cl)(en)] (3): A procedure similar to that described
for 2 was used, but with the addition of ethylenediamine (16 μL,
0.24 mmol) before ligand 1. A brown crystalline solid was obtained.
Yield: 0.097 mg (84%). C14H23ClN6RuS2 (475.7): calcd. C 35.33,
H 4.84, N 17.66; found C 35.36, H 4.87, N 17.64. IR (KBr): ν =
˜
Experimental Section
1562 ν(C=N), 1030 νas(C=S), 792 νs(C–S), 3233 νas(NH2),
1
3127 cm–1 νs(NH2). UV/Vis: λ (log ε) = 297 nm (3.53, MLCT). H
General Remarks: All chemicals used were of high quality and pur-
chased from Aldrich. The solvents were dried and distilled before
use.
NMR (250 MHz, CD3OD, 298 K): δ = 2.10 (s, 6 H, Me3), 2.31 (s,
6 H, Me5), 5.86 (s, 2 H, H4), 7.12 (s, 1 H, CH), 2.24/2.33 [t, 4 H,
CH2(en)] ppm. 13C{1H} NMR/DEPT-135 (62.89 MHz, CD3OD,
298 K): δ = 12.4 (+, Me5), 13.8 (+, Me3), 76.3 (+, CH), 105.1 (+,
Spectroscopy: The electronic spectra were recorded with an Ultro-
spec III spectrophotometer (Pharmacia-LKB) interfaced with a
microcomputer for data acquisition. IR spectra were recorded with
a Perkin–Elmer 883 FT-IR spectrometer, with samples prepared as
KBr tablets or as CH2Cl2 solutions in CaF2 cells. NMR spectra
were obtained with a Bruker AC 250 (62.89 MHz for 13C) spec-
trometer equipped with an ASPECT 3000 computer. All samples
were dissolved in CD3OD (30 mg/0.4 mL) and recorded at 300 K.
The reported chemical shifts (δ) are expressed in ppm and refer-
enced to tetramethylsilane (TMS). The nature of each carbon atom
was determined using the DEPT technique with proton pulses at θ
= 135°. X-band EPR spectra of nitrosylruthenium complexes at
120 K were obtained on a Bruker EMX-300 X-band spectrometer
operating at a frequency of 9.5 GHz or aBruker ESP 300 spectrom-
eter operating at 100 KHz field modulation for dichloromethane
solutions and polycrystalline samples, respectively. The frequencies
were measured with a Hewlett–Packard 5352B frequency counter.
The temperature was regulated with an Oxford Instruments ESR
900 continuous flow helium cryostate (low temperature) and
Bruker RS-232 continuous flow nitrogen thermostat (room tem-
perature).
–
C4), 143.2 (0, C5), 152.5 (0, C3), 239.6 (0, CS2 ) ppm.
[Ru(bdmpzdta)2] (4): A procedure similar to that described for 2
was used, but with the addition of a double quantity of ligand 1
(0.138 g, 0.48 mmol) in four portions. A brown crystalline solid was
obtained. Yield: 0.141 g (90%). C24H30N8RuS4 (659.2): calcd. C
43.70, H 4.55, N 16.99; found C 43.73, H 4.58, N 16.97. IR (KBr):
ν = 1562 ν(C=N), 1029 ν (C=S), 790 cm–1 νs(C–S). UV/Vis: λ (log
˜
as
1
ε) = 298 nm (3.14, MLCT). H NMR (250 MHz, CD3OD, 298 K):
δ = 2.15 (s, 12 H, Me3), 2.35 (s, 12 H, Me5), 6.06 (s, 4 H, H4),
7.05 (s, 2 H, CH) ppm. 13C{1H} NMR/DEPT-135 (62.89 MHz,
CD3OD, 298 K): δ = 13.4 (+, Me5), 12.2 (+, Me3), 75.7 (+, CH),
–
103.5 (+, C4), 144.9 (0, C5), 157.9 (0, C3), 230.5 (0, CS2 ) ppm.
[Ru(bdmpzdta)(Cl)2(NO)] (5): [RuCl3(NO)] (0.050 g, 0.21 mmol)
was dissolved in methanol (20 mL) and ligand
1 (0.060 g,
0.21 mmol) was added in two portions. The reaction mixture was
stirred for 4 h under an inert atmosphere. The solvent was removed
from the resulting reddish suspension, the product was dissolved in
dichloromethane, and the LiCl was filtered off. The solvent was
removed from the filtrate under vacuum to give a brown hygro-
scopic solid. Yield: 0.071 mg (70%). C12H15Cl2N5ORuS2 (481.2):
calcd. C 29.93, H 3.12, N 14.55; found C 29.96, H 3.16, N 14.52.
Techniques for Kinetic Determinations: The UV/Vis kinetic determi-
nations were performed spectrophotometrically at 300 K with the
IR (KBr): ν = 1864 ν(NO), 1560 ν(C=N), 1031 ν (C=S), 785 cm–1
˜
appropriate software. Methanolic solutions containing 5.8×10–4
m
as
νs(C–S). IR (CH2Cl2): ν(NO) = 1860 cm–1. UV/Vis: λ (log ε) =
RuCl3 and corresponding amounts of 1 were studied in 1-cm quartz
optical cells.
1
284 nm (3.14, MLCT). H NMR (250 MHz, CD3OD, 298 K): δ =
2.11 (s, 6 H, Me3), 2.42 (s, 6 H, Me5), 5.93 (s, 2 H, H4), 7.32 (s,
1 H, CH) ppm. 13C{1H} NMR/DEPT-135 (62.89 MHz, CD3OD,
298 K): δ = 10.3 (+, Me5), 13.0 (+, Me3), 76.4 (+, CH), 105.2 (+,
Electrochemical Measurements: Electrochemical measurements
were carried out with a Yanaco P-900 cyclic polarograph coupled
to a Graphted WX1000 X-Y recorder using a standard three-
holder cell. Glassy carbon, Pt and Ag/AgCl (saturated) were used
as working, counter and reference electrodes, respectively. The cy-
clic voltammograms of the complexes (0.01 m) in DMSO solution,
which had been previously deoxygenized, were recorded with tetra-
n-butylammonium tetrafluoroborate (0.2 m) as supporting electro-
lyte.
–
C4), 140.4 (0, C5), 146.8 (0, C3), 218.1 (0, CS2 ) ppm.
[Ru(bdmpzdta)(en)(NO)]Cl2 (6): A procedure similar to that de-
scribed for 5 was used, but with the addition of ethylenediamine
(14 μL, 0.21 mmol) before ligand 1. A brown crystalline solid was
obtained. Yield: 0.085 g (75%). C14H23Cl2N7ORuS2 (541.2): calcd.
C 31.05, H 4.25, N 18.11; found C 31.08, H 4.29, N 18.13. IR
(KBr): ν = 1860 ν(NO), 1562 ν(C=N), 1033 ν (C=S), 785 ν (C–S),
˜
as
s
[{Li(bdmpzdta)(H2O)}4] (1): This ligand was prepared as reported
3232 νas(NH2), 3130 cm–1 νs(NH2). IR (CH2Cl2): ν(NO)
=
previously.[10,14]
1860 cm–1. UV/Vis: λ (log ε) = 288 nm (3.34, MLCT). 1H NMR
(250 MHz, CD3OD, 298 K): δ = 2.31 (s, 6 H, Me3), 2.10 (s, 6 H,
Me5), 5.85 (s, 2 H, H4), 7.15 (s, 1 H, CH), 2.20/2.40 [t, 4 H,
CH2(en)] ppm. 13C{1H} NMR/DEPT-135 (62.89 MHz, CD3OD,
298 K): δ = 10.7 (+, Me5), 13.5 (+, Me3), 75.2 (+, CH), 106.0 (+,
[{Ru(bdmpzdta)(Cl)(H2O)}]2 (2): RuCl3 (0.050 g, 0.24 mmol) was
dissolved in methanol (20 mL) and ligand 1 (0.069 g, 0.24 mmol)
was added in two portions. The mixture was stirred for 4 h in an
inert atmosphere. The solvent was removed from the resulting
brownish suspension, the product was dissolved in dichlorometh-
–
C4), 140.3 (0, C5), 147.7 (0, C3), 220.3 (0, CS2 ) ppm.
Eur. J. Inorg. Chem. 2005, 3135–3140
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3139

M. Ortiz, A. Penabad, A. Díaz, R. Cao, A. Otero, A. Antiñolo, A. Lara
FULL PAPER
[Ru(bdmpzdta)2(NO)]Cl (7): A procedure similar to that described
for 5 was used, but with the addition of a double quantity of ligand
1 (0.120 g, 0.42 mmol) in four portions. A brown crystalline solid
was obtained. Yield: 0.137 g (90%). C24H30RuN9OS4Cl (724.7):
calcd. C 39.75, H 4.14, N 17.39; found C 39.77, H 4.16, N 17.36.
[1] S. Moncada, R. M. J. Palmer, E. A. Higgs, Biochem. Pharma-
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ney, Br. J. Pharmacol. 1997, 122, 1441–1448.
IR (KBr): ν = 1859 ν(NO), 1560 ν(C=N), 1033 ν (C=S), 786 cm–1
˜
as
νs(C–S). IR (CH2Cl2): ν(NO) = 1862 cm–1. UV/Vis: λ (log ε) =
1
289 nm (3.20, MLCT). H NMR (250 MHz, CD3OD, 298 K): δ =
[4] Y. Chen, F. T. Lin, R. E. Shepherd, Inorg. Chem. 1999, 38, 973–
2.15 (s, 12 H, Me3), 2.30 (s, 12 H, Me5), 6.08 (s, 4 H, H4), 7.07 (s,
2 H, CH) ppm. 13C{1H} NMR/DEPT-135 (62.89 MHz, CD3OD,
298 K): δ = 10.5 (+, Me5), 13.2 (+, Me3), 70.3 (+, aliphatic CH of
CS2– coordinated moiety), 83.4 (+, aliphatic CH of CS2– uncoordi-
nated moiety), 105.6/106.2 (+, C4), 142.8 (0, C5), 145.7 (0, C3),
983.
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silla, J. Tejeda, A. Lara-Sánchez, L. F. Sánchez-Barba, M.
Fernández-López, A. M. Rodríguez, I. López-Solera, Inorg.
Chem. 2002, 41, 5193–5202.
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5002–5010; b) R. D. Feltham, J. H. Enemark, Top. Stereochem.
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[12] a) K. Y. Lee, D. J. Kuchynka, K. Kochi, Inorg. Chem. 1990,
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sio, Coord. Chem. Rev. 2003, 245, 73–83.
–
–
211.0 (0, coordinated CS2 ), 243.2 (0, uncoordinated CS2 ) ppm.
Interaction of 2, 3 or 4 with NO in Solution: Nitric oxide was ob-
tained from the reaction between copper and nitric acid (5 m) under
a nitrogen atmosphere using Schlenk techniques at 293 K. The gas-
eous product(s) of this reaction were passed through NaOH(conc)
traps to remove nitrogen oxides other than nitric oxide. Com-
pounds 2, 3 and 4 (0.08–0.11 mmol) were each dissolved in 20 mL
of dichloromethane in a Schlenk flask and deoxygenated with oxy-
gen-free nitrogen. These 10–3 m solutions had nitric oxide bubbled
through them for 20 min and were then stirred for 6 h whilst main-
taining anaerobic conditions under nitrogen. The solutions, which
were initially brown, became reddish. The corresponding products
were isolated by evaporating the solvent under vacuum.
Acknowledgments
[14] A. Otero, J. Fernández-Baeza, A. Antiñolo, J. Tejeda, A. Lara-
Sánchez, Dalton Trans. 2004, 1499–1510.
This research was supported by the Universidad de Castilla-La
Mancha, Spain.
Received: December 30, 2004
Published Online: June 28, 2005
3140
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3135–3140