Synthesis, X-ray crystal structure, and NMR characterisation of thiolate-bridged dinuclear Ni(II), Pd(II) and Pt(II) complexes of didentate ligands with NS-donor set

Article abstract of DOI:10.1016/S0020-1693(03)00333-5

Thiolate-bridged dinuclear nickel(II), palladium(II) and platinum(II) complexes with N-(2-mercaptoethyl)-3,5-dimethylpyrazole (Hmed), [MCl(med)] ₂ (M=Ni (1), Pd (2), Pt (3)), have been synthesised and characterised by elemental analyses, conductivity, IR, electronic spectra and NMR spectroscopies. The crystal structure of 2 was determined by a single-crystal X-ray diffraction method. The structure consists of thiolate-bridged dinuclear units. Each Pd(II) atom is coordinated by a pyrazolic nitrogen, one chlorine and two bridging sulfur atoms. When the synthesis of complex 1 was carried out in acetonitrile and in the presence of oxygen, [NiCl₃(Hdeds)] (4) was formed (deds=1,1′- (dithiodiethylene)bis(3,5-dimethylpyrazole)). The crystal structure of this complex was also determined by single-crystal X-ray diffraction method. The structure consists of nickel(II) ions coordinated by three chloride ions and one pyrazolic nitrogen atom. Ligand deds is the result of the oxidation of N-(2-mercaptoethyl)-3,5-dimethylpyrazole (Hmed).

Full text of DOI:10.1016/S0020-1693(03)00333-5

Inorganica Chimica Acta 355 (2003) 87ꢁ94
/
www.elsevier.com/locate/ica
Synthesis, X-ray crystal structure, and NMR characterisation of
thiolate-bridged dinuclear Ni(II), Pd(II) and Pt(II) complexes of
didentate ligands with NS-donor set
Jordi Garc´ıa-Anto´n a, Josefina Pons a,*, Xavier Solans b, Merce` Font-Bardia b,
Josep Ros a,*
a Departament de Qu´ımica, Facultat de Cie`ncies, Universitat Auto`noma de Barcelona, 08193-Bellaterra-Cerdanyola, Barcelona, Spain
b Cristal.lografia, Mineralogia i Dipo`sits Minerals, Universitat de Barcelona, Mart´ı i Franque`s s/n, 08028 Barcelona, Spain
Received 29 January 2003; accepted 16 April 2003
Abstract
Thiolate-bridged dinuclear nickel(II), palladium(II) and platinum(II) complexes with N-(2-mercaptoethyl)-3,5-dimethylpyrazole
(Hmed), [MCl(med)]2 (MꢀNi (1), Pd (2), Pt (3)), have been synthesised and characterised by elemental analyses, conductivity, IR,
/
electronic spectra and NMR spectroscopies. The crystal structure of 2 was determined by a single-crystal X-ray diffraction method.
The structure consists of thiolate-bridged dinuclear units. Each Pd(II) atom is coordinated by a pyrazolic nitrogen, one chlorine and
two bridging sulfur atoms. When the synthesis of complex 1 was carried out in acetonitrile and in the presence of oxygen,
[NiCl3(Hdeds)] (4) was formed (dedsꢀ1,1?-(dithiodiethylene)bis(3,5-dimethylpyrazole)). The crystal structure of this complex was
/
also determined by single-crystal X-ray diffraction method. The structure consists of nickel(II) ions coordinated by three chloride
ions and one pyrazolic nitrogen atom. Ligand deds is the result of the oxidation of N-(2-mercaptoethyl)-3,5-dimethylpyrazole
(Hmed).
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Nickel; Palladium; Platinum; Dinuclear; N,S ligands
1. Introduction
the bonding, spectral and redox properties of bioinor-
ganic compounds [1a,5,6,7].
The known tendency of thiolate ligands to give highly
insoluble neutral complexes of polymeric nature has led
to new synthetic strategies [1] and thus has enabled the
obtaining of structural information on metal-thiolate
complexes [2].
The Ni(m2-SR)xNi has attracted much attention to
model the active site of the nickel-enzymes [8], in
particular for the hydrogenases, metalloenzymes which
catalyse H2ꢀ
/
2Hꢂꢂ2eꢃ. Only recently, however, it has
/
been established that the active site contained a dime-
tallic substructure [9].
Discrete first-row transition-metal complexes featur-
Pt(m2-SR)xPt complexes have been ascribed as anti-
tumor drugs [10]. However, their inactivation is thought
probably to be due to the bonding of platinum atoms to
sulfur-containing biomolecules [11].
ing central M(m2-SR)xM cores (xꢀ
/
1ꢁ3) have come
/
under increased investigation in the past several years
[3]. There are several M(m2-SR)xM type complexes [4],
most of which have been studied in attempts to mimic
In recent years, we have studied and reported the
synthesis and characterisation of ligands N-alkylamino-
pyrazole [12], N-hydroxyalkylpyrazole [13], N-phosphi-
nopyrazole [14] and more recently ligands containing
pyrazolyl and thioether groups [15].
* Corresponding authors. Tel.: ꢂ
3101.
E-mail address: josefina.pons@uab.es (J. Pons).
/
34-93-581 2895; fax: ꢂ34-93-581
/
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00333-5

88
J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ94
/
In the present paper, we describe the examination of
cmꢃ1 which is characteristic of n(Cꢁ
/
C) and n(Cꢁ
/N)
dinuclear Ni(II), Pd(II) and Pt(II) complexes of the
ligand with NS-donor set N-(2-mercaptoethyl)-3,5-di-
methylpyrazole (Hmed). The reactivity of dinuclear
Ni(II) complex in acetonitrile with the HCl formed in
the reaction mixture in the presence of oxygen, leads to a
new mononuclear Ni(II) complex with a NiCl3N core.
Thiolate ligands medꢃ are oxidised to disulfide
1,1?(dithiodiethylene(bis(3,5-dimethylpyrazole) (deds)
in this reaction (Fig. 1).
absorption bands of pyrazole rings. However, complex 4
shows two absorption bands in this region (1592 and
1554 cmꢃ1), which were assigned to the protonated and
complexed pyrazolyl groups, respectively [20].
The IR spectra of complexes in the region 500ꢁ
cmꢃ1 were also studied [21]. Complexes 1ꢁ
3 show three
well-defined bands corresponding to n(MꢀS) at 366ꢁ
315 cmꢃ1, n(Mꢀ 333 cmꢃ1 and n(Mꢀ
Cl) at 388ꢁ N) at
513ꢁ
450 cmꢃ1. For complex 4 only two bands were
assigned for n(Niꢀ N) at 484
Cl) at 375 cmꢃ1 and n(Niꢀ
cmꢃ1
/
100
/
/
/
/
/
/
/
NMR studies of complexes 1ꢁ/3 and the X-ray crystal
/
/
structures of 2 and 4 are also presented.
.
Electronic spectra of the complexes 1 and 4 were
measured in acetonitrile. Complex 1 shows two intense
ligand-to-metal charge transfer bands at 524 nm (oꢀ
molꢃ1 cmꢃ1l) and 416 nm (oꢀ1010 l molꢃ1 cmꢃ1
[22]. Electronic spectrum of complex 4 exhibits one dꢁ
band at 616 nm (oꢀ
/
411
2. Results and discussion
/
)
/
d
2.1. Synthesis and spectroscopic properties of the
complexes
/
215 l molꢃ1 cmꢃ1), which can be
3
attributed to the T1(F)0
/
3T1(P) transition, character-
istic for tetrahedral Ni(II) complexes. Absorption bands
at 447 and 362 nm for 2 and 384 nm for 3 can be
The N-(2-mercaptoethyl)-3,5-dimethylpyrazole
(Hmed) (Fig. 2) was synthesised according to a proce-
dure previously described by Bouwman et al. [16].
assigned to dꢁd and charge transfer transitions [23].
/
Complexes [M(med)Cl]2 (Mꢀ
Pt(II) (3)) were obtained by reaction of the ligand Hmed
with 6H2O, [PdCl2(CH3CN)2] [17] or
NiCl2×
[PtCl2(CH3CN)2] [18], respectively. Reaction of Hmed
with NiCl2×6H2O always gave a secondary product (4)
in very small quantities. This compound (4) was
formulated as [NiCl3(Hdeds)] being deds 1,1?-(dithio-
diethylene)bis(3,5-dimethylpyrazole), the product of
oxidation of medꢃ. Complex [NiCl3(Hdeds)] (4) was
/
Ni(II) (1), Pd(II) (2) and
2.2. NMR experiments
/
1H and 13C NMR spectra of compounds 1, 2 and 3
were recorded in CDCl3 and show the signals of the
coordinated ligands. NMR data are reported in the
experimental section. From the structure of complexes
1, 2 and 3 it can be seen that the two protons of each
/
CH2 in the Sꢀ
/
CH2ꢀ
/
CH2ꢀ
/
N chain are diastereotopic,
obtained directly by treatment of NiCl2×
Hmed in acetonitrile, in the presence of oxygen.
Elemental analyses of products 1ꢁ4 are consistent
/6H2O with
thus leading to four groups of signals, which can be
associated to a single hydrogen each. This happens
because of the rigid conformation of the ligand when it
is complexed. In this way, each group of signals can be
assigned as doublets of doublets of doublets (Fig. 2).
HMQC spectra (Fig. 3) were used to assign protons
/
with the proposed molecular formula. Conductivity
values in acetonitrile for all complexes are in agreement
with a non-electrolyte nature of complexes. The re-
ported values for 10ꢃ3 M solutions of non-electrolyte
complexes in acetonitrile are lower than 120 Vꢃ1 cm2
molꢃ1 [19].
H1R and H1S to the two doublets of doublets of doublets
of lower d and H2R and H2S to those of higher d.
NOESY spectra (Fig. 4) allowed us to differentiate
H2R from H2S and CH3(4) from CH3(7): the singlet that
The main difference among IR spectra of complexes
1ꢁ
of the n(Sꢀ
because ligand Hmed acts as a thiolate when complexed.
Complexes 1ꢁ3 present one band between 1550ꢁ1554
/
3 and the IR spectrum of the free ligand is the absence
appears at 2.56 ppm shows NOE interaction only with
H5 and was assigned to CH3(4). The singlet at 2.29 ppm,
besides having NOE interaction with H5, shows strong
NOE interaction with the doublets of doublets of
/
H) band found at 2543 cmꢃ1. This happens
/
/
Fig. 1. Synthesis of [NiCl3(Hdeds)] (4).

J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ
/
94
89
Fig. 2. The 400 MHz 1H NMR and gNMR simulated spectra for NCH2CH2S fragment of [PdCl(med)]2 (2), including (a) the numbering and (b) the
dihedral angles for the NCH2CH2S fragment of [MCl(med)]2 (MꢀNi (1), Pd (2) or Pt (3)).
/
doublets at 4.60 ppm and weak NOE interaction with
the doublets of doublets of doublets at 4.87 ppm and
was assigned to CH3(7). From the X-ray structure of 2,
it can be seen that the nearest proton to CH3(7) is H2S
and therefore should have a stronger NOE interaction.
This information leads us to assign it to the doublets of
doublets of doublets at 4.60 ppm and H2R to the signal
at 4.87 ppm.
Coupling constants (obtained from the gNMR gen-
1
erated H NMR simulated spectra, Fig. 2) helped us to
differentiate H1R and H1S. These coupling constants
agree with the conformation of the Sꢀ
/
CH2ꢀ
/
CH2ꢀ/N
chain as seen in Fig. 2, which has been corroborated by
a X-ray crystal study.
2
3
Geminal J and :
/
1808 J coupling constants have
significantly higher values than :
/
308 and :
/
608 3J
Fig. 3. The 250 MHz 2D HMQC spectrum of [PdCl(med)]2 (2).
Fig. 4. The 250 MHz 2D NOESY spectrum of [PdCl(med)]2 (2).

90
J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ94
/
Table 1
1H NMR results: chemical shifts (ppm) and 1Hꢁ1
(Hz)
Table 2
Selected bond lengths (A) and angles (8) for 2 and 4 with estimated
standard deviations (e.s.d.s.) in parentheses
˚
/
H coupling constants
Compound
1 (CDCl3)
2 (CDCl3)
3 (CDCl3)
2
4
d H (2S)
d H (2R)
d H (1R)
d H (1S)
2J(2R,2S)
2J(1R,1S)
3J(1R,2S)
3J(1S,2S)
3J(1R,2R)
3J(1S,2R)
3J(Pt,1R)
3J(Pt,1S)
4.49
5.60
0.75
2.63
4.60
4.87
1.69
3.85
4.27
5.00
1.67
3.97
Bond lenths
Pd(1)ꢀ
Pd(1)ꢀ
Pd(1)ꢀ
Pd(1)ꢀ
Pd(1)ꢀ
Pd(2)ꢀ
Pd(2)ꢀ
Pd(2)ꢀ
Pd(2)ꢀ
/
N(1)
S(1)
2.057(3)
2.2804(10) Niꢀ
2.2807(9)
Niꢀ
2.3379(10) Niꢀ
Niꢀ
/
N(1)
Cl(1)
Cl(2)
Cl(3)
2.011(3)
/
/
2.2916(11)
2.2492(12)
2.2386(12)
/
S(2)
/
ꢃ
ꢃ/
/
14.8
13.2
2.2
ꢃ
ꢃ/
/
15.4
13.9
2.2
ꢃ
ꢃ/
/
14.9
13.7
2.1
/
Cl(1)
Pd(2)
N(3)
S(2)
/
/
3.1175(4)
/
2.056(3)
3.7
4.4
4.0
/
2.2746(10)
2.2864(10)
2.3409(12)
11.7
1.5
11.7
1.5
11.6
1.8
/
S(1)
Cl(2)
/
ꢁ/
ꢁ/
ꢁ/
ꢁ/
45.0
49.8
Bond angles
N(1)ꢀPd(1)ꢀ
N(1)ꢀPd(1)ꢀ
S(1)ꢀPd(1)ꢀ
N(1)ꢀPd(1)ꢀ
S(1)ꢀPd(1)ꢀ
S(2)ꢀPd(1)ꢀ
N(3)ꢀPd(2)ꢀ
N(3)ꢀPd(2)ꢀ
S(2)ꢀPd(2)ꢀ
N(3)ꢀPd(2)ꢀ
S(2)ꢀPd(2)ꢀ
S(1)ꢀPd(2)ꢀ
/
/
S(1)
91.51(10)
170.42(10)
79.29(4)
93.49(10)
173.65(4)
95.87(4)
92.06(9)
171.24(9)
79.29(4)
93.20(9)
173.54(4)
95.52(4)
N(1)ꢀ
N(1)ꢀ
N(1)ꢀ
Cl(1)ꢀ
Cl(1)ꢀ
Cl(2)ꢀ
/
Niꢀ
Niꢀ
Niꢀ
Niꢀ
Niꢀ
Niꢀ
/
Cl(1)
Cl(2)
Cl(3)
104.79(9)
105.13(9)
119.41(9)
/
/S(2)
/
/
/
/
S(2)
/
/
/
/Cl(1)
/
/
Cl(2) 105.29(5)
coupling constants [24] (Fig. 2). Thus, H1R should
correspond to the doublets of doublets of doublets at
1.69 ppm and H1S to the one at 3.85 ppm (Table 1).
/
/
Cl(1)
/
/
Cl(3) 105.21(5)
/
/
Cl(1)
/
/
Cl(3) 115.67(5)
/
/S(2)
/
/S(1)
/
/
S(1)
2.3. Crystal and molecular structure of [Pd(med)Cl]2
(2)
/
/Cl(2)
/
/
Cl(2)
/
/
Cl(2)
The structure of 2 (Fig. 5) consists of dimeric
[Pd(med)Cl]2 units linked by van der Waals forces.
Each palladium atom is coordinated by two thiolate-
bridging sulfurs (in anti conformation), one pyrazole
nitrogen and one chloride ion in a distorted square-
planar geometry. Table 2 lists some selected bond
distances and bond angles for this complex.
than those found in the literature for dimeric complexes
with PdClNS2 core [6cꢁ6d].
PdꢀN distances are smaller and Pdꢀ
distances are similar to the ones found for related
complexes [6]. However, PdꢀN bond distances are of
the same order as the ones found in the literature for
complexes containing PdꢀNpz (pzꢀpyrazole) [13,15].
The pyrazoleꢁthiolate ligand acts as a bidentate
chelate (as well as bridging ligand), forming two Pdꢀ
SꢀCꢀCꢀNꢀN rings. These two six-membered rings
have boat conformation. Bite angles S(1)ꢀPd(1)ꢀN(1)
and N(3)ꢀPd(2)ꢀS(2) are 91.5(1)8 and 92.1(1)8, respec-
tively.
The distortion of the boat in six-membered rings are
DCS(Pd1)ꢀ10.1(3)8, DC2(S1ꢀC1)ꢀ42.4(4)8 and
DCS(Pd2)ꢀ13.1(3)8, DC2(S2ꢀC8)ꢀ40.5(4)8 for Pd1ꢀ
S1ꢀC1ꢀC2ꢀN2ꢀN1 and Pd2ꢀS2ꢀC8ꢀC9ꢀN4ꢀN3, re-
spectively.
/
/
/
Cl and Pdꢀ
/
S
/
The largest deviations to the mean planes that contain
˚
the four donor atoms and the Pd atom are 0.052(1) A in
/
/
˚
˚
0.048(3) A in N(3) for Pd(2) and 0.062(3) A
S(2) and ꢃ
/
/
in N(2) and ꢃ
/
0.068(1) in S(1) for Pd(1).
The two planar PdClNS2 units are joined via two
/
/
/
/
/
bridging thiolate ligands forming a four-membered ring,
/
/
which is CR-form with Pd
/
ꢀ ꢀ ꢀ
3.1174(4) and 2.910(1) A, respectively. The dihedral
angles between the planes Pd(1)ꢀS(1)ꢀPd(2) and Pd(1)ꢀ
S(2)ꢀPd(2) is 54.84(4)8. This dihedral angle is larger
/
Pd and S
/
ꢀ ꢀ ꢀ
/
S distances
/
/
˚
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2.4. Crystal and molecular structure of [NiCl3(Hdeds)]
(4)
The structure of 4 consists of discrete [NiCl3(Hdeds)]
units, linked by hydrogen bonds (Fig. 6). Nickel atom is
coordinated by three terminal chloride ions and one
pyrazole nitrogen in a slightly distorted tetrahedral
geometry.
Fig. 5. ORTEP drawing of [PdCl(med)]2 (2) (293 K determination)
showing the atom numbering scheme. Fifty percent probability
amplitude displacement ellipsoids are shown.

J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ
/
94
91
Analyses (C, N, H, S) were performed in our
analytical laboratory on a Carlo Erba CHNS EA-1108
instrument. Conductivity measurements were performed
at room temperature in 10ꢃ3 M acetonitrile solutions
employing a Crison, micro CM 2200 conductimeter.
Infrared spectra were recorded from KBr pellets or
polyethylene mulls in the range 4000ꢁ
100 cmꢃ1 under a
/
nitrogen atmosphere. Electronic spectra in solution were
run on a Kontron-Uvikon 860 in acetonitrile between
750 and 350 nm. The 1H NMR, 13C{1H} NMR, HMQC
and NOESY spectra were obtained either on a Bruker
250 MHz or Bruker 400 MHz instrument. Chemical
shifts (d) were determined relative to internal TMS and
are given in ppm.
Fig. 6. ORTEP drawing of [NiCl3(Hdeds)] (4) (293 K determination)
showing the atom numbering scheme. Fifty percent probability
amplitude displacement ellipsoids are shown.
Niꢀ
/
N and Niꢀ
/
Cl distances are similar to those found
in the literature for Ni(II) complexes containing pyr-
azolyl groups and at least one coordinated Cl atom [25].
The azine nitrogen in the uncoordinated pyrazole
(N12) is protonated. The positive charge is cancelled out
by the negative charge that is provided by the third
chloride ion linked to Ni(II), forming a zwitterionic
structure. Pyrazole N(12) atom is intermolecularly
hydrogen bridged to Cl(1) atom from another molecule,
3.2. Synthesis
3.2.1. Preparation of [Ni(med)Cl]2 (1)
To a solution of 0.345 g (2.21 mmol) of N-(2-
mercaptoethyl)-3,5-dimethylpyrazole in 5 ml of absolute
ethanol (light brown) and 2 ml of triethyl ortoformate
was added dropwise a solution of 0.525 g (2.21 mmol) of
NiCl2×/6H2O in absolute ethanol (green). Solution
thereby linking the molecules into a chain (the N(12)ꢀ
/
H
bond length is 0.86(4) A and the contact parameters
turned into dark brown colour and a precipitate of the
same colour was formed. After stirring for 1 h, the
precipitate was filtered off and dried in vacuum. Yield:
0.46 g (83%), C14H22Cl2N4Ni2S2 (498.78): C 33.71, H
4.45, N 11.23, S 12.86; Found: C 34.06, H 4.46, N 11.24,
˚
˚
between N(12)ꢀ
N(12) Cl(1), 3.158(4) A; symmetry code (i): x, y, 1ꢂ
ꢀ ꢀ ꢀ
z).
/
H and Cl(1) are: H
/
ꢀ ꢀ ꢀ
/
Cl(1), 2.30(4) A;
˚
/
/
/
No other complex with NiCl3N core (terminal Cl) has
been fully described in the literature. Only one complex
with this core (but with one bridged chloride ion) was
found, but due to the poor quality of the crystal it could
not be further described in the corresponding paper [26].
The most similar complex to the one presented here is
a copper complex with CuCl3N core (pyrazole nitrogen
S 12.53%. Conductivity (Vꢃ1 cm2 molꢃ1, 1.06 10ꢃ3
in acetonitrile): 14.0, IR (KBr, cmꢃ1): n(Cꢀ
H)al 2982ꢁ
2921, n(CꢁC), n(CꢁN) 1554, d(CH3)as 1469ꢁ1421,
d(CH3)s 1310, d(CꢀH)oop 774. IR (polyethylene,
cmꢃ1): n(Niꢀ
N)as 463, n(NiꢀCl) 388, n(NiꢀS) 366.
UVꢁ
Vis (acetonitrile, 1.1 10ꢃ3 M, nm), l(o): 524(411),
416(1010). 1H NMR (400 MHz, CDCl3) dꢀ
2.19 (s, 6H,
Me), 2.74 (s, 6H, Me), 0.72/2.60/4.47/5.58 (4 ddd, 8H,
pzꢀCH2 ꢀCH2), 5.79 (s, 2H, pzꢀ
CH). 13C{1H} NMR
(100 MHz, CDCl3) dꢀ11.9 (Me), 15.7 (Me), 24.7 (Sꢀ
CH2 ꢀCH2), 50.4 (pzꢀCH2 ꢀCH2), 108.4 (pzꢀCH),
142.1, 152.8 (pzꢀC).
M
/
/
/
/
/
/
/
/
/
/
/
and terminal chloride): [Cu(daeH)Cl3] where daeHꢀN-
/
(2-(3,5-dimethyl-1-pyrazolyl)ethyl)hydro-ethylammo-
nium [27].
/
/
/
/
/
/
/
/
/
/
3. Experimental
3.2.2. Preparation of [Pd(med)Cl]2 (2) and
[Pt(med)Cl]2 (3)
3.1. Generals methods
A solution of 0.100 g (0.39 mmol) of [PdCl2
(CH3CN)2] (orange) or 0.076 g (0.22 mmol) of
[PtCl2(CH3CN)2] (yellow) in 5 ml of dichloromethane
was added dropwise to a solution containing (Pd: 0.061
g, 0.39 mmol; Pt: 0.034 g, 0.22 mmol) of N-(2-
mercaptoethyl)-3,5-dimethylpyrazole in 5 ml of dichlor-
omethane (light brown). After 12 h stirring, solvent was
removed in vacuum. For Pd complex, the resulting
precipitate was then filtered off and washed with diethyl
ether, yielding the desired compound. Pt complex was
further purified by chromatography (silica gel 60) using
methanol-dichloromethane (1:9) as eluent to give the
desired product as a yellow precipitate.
Preparations were performed using usual vacuum line
and Schlenk techniques. All reagents were commercial
grade materials and were used without further purifica-
tion. Acetonitrile and dichloromethane were dried and
distilled by standard methods and previously deoxyge-
nated in the vacuum line.
N-(2-mercaptoethyl)-3,5-dimethylpyrazole was pre-
pared according to the published methods [16].
Samples
of
[PdCl2(CH3CN)2]
[17]
and
[PtCl2(CH3CN)2] [18] were prepared as described in
the literature.

92
J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ94
/
2: Yield: 0.112 g (98%), C14H22Cl2N4S2Pd2 (594.23):
C 28.30, H 3.73, N 9.43, S 10.76; Found: C 28.65, H
3.91, N 9.20, S 10.44%. Conductivity (Vꢃ1 cm2 molꢃ1
7.08 10ꢃ4 M in acetonitrile): 11.2, IR (KBr, cmꢃ1):
n(CꢀH)ar 3119ꢁ3078, n(CꢀH)al 2976ꢁ2918, n(CꢁC),
n(CꢁN) 1550, d(CH3)as 1466ꢁ1422, d(CH3)s 1312,
d(CꢀH)oop 814ꢁ
771. IR (polyethylene, cmꢃ1): n(Pdꢀ
N)as 450, n(PdꢀCl) 360, n(PdꢀS) 315. UVꢁVis (aceto-
nitrile, 1.0 10ꢃ3 M, nm), l: 447, 362. H NMR (400
MHz, CDCl3) dꢀ2.29 (s, 6H, Me), 2.56 (s, 6H, Me),
1.69/3.85/4.60/4.87 (4 ddd, 8H, pzꢀCH2 ꢀCH2), 5.94 (s,
2H, pzꢀ
CH). 13C{1H} NMR (100 MHz, CDCl3) dꢀ
12.4 (Me), 15.6 (Me), 28.0 (SꢀCH2 ꢀCH2), 52.6 (pzꢀ
CH2 ꢀCH2), 108.2 (pzꢀCH), 141.9, 152.4 (pzꢀC).
Table 3
Crystallographic data for 2 and 4
,
Compound
2
4
Empirical formula
Molecular mass (g)
Temperature (K)
Crystal system
C
14H22Cl2N4Pd2S2 C14H23Cl3N4NiS2
/
/
/
/
/
594.18
293(2)
triclinic
476.54
293(2)
triclinic
/
/
/
/
/
/
/
/
¯
P/1 (no. 2)
¯
P1 (no. 2)
Space group
/
1
Unit cell dimensions
˚
a (A)
˚
8.649(1)
10.484(1)
11.946(1)
104.685(1)
95.166(1)
95.912(1)
1034.64(2)
2
10.545(1)
10.488(1)
10.944(1)
82.961(2)
71.510(1)
64.282(2)
1034.0(2)
2
/
b (A)
˚
c (A)
/
/
/
/
a (8)
b (8)
g (8)
/
/
/
/
/
/
3
˚
V A
Z
3: Yield: 0.044 g (52%), C14H22Cl2N4S2Pt2 (771.54): C
21.79, H 2.87, N 7.26, S 8.32; Found: C 21.67, H 2.52, N
6.99, S 8.03%. Conductivity (Vꢃ1 cm2 molꢃ1, 1.13 10ꢃ3
Dcalc (g cmꢃ3
)
1.907
2.202
584
1.531
1.532
492
m (mmꢃ1
F(0 0 0)
)
M in acetonitrile): 12.5, IR (KBr, cmꢃ1): n(Cꢀ
/
H)al
N) 1552, d(CH3)as 1467ꢁ
H)oop 801. IR (polyethylene,
N)as 513, n(PtꢀCl) 330, n(PtꢀS) 320. UVꢁ
Vis (acetonitrile, 1.6 10ꢃ3 M, nm), l: 384. H NMR
(400 MHz, CDCl3) dꢀ2.23 (s, 6H, Me), 2.54 (s, 6H,
Me), 1.69/3.98/4.29/5.02 (4 ddd, 8H, pzꢀCH2 ꢀCH2),
5.94 (s, 2H, pzꢀ
CH). 13C{1H} NMR (100 MHz, CDCl3)
dꢀ12.3 (Me), 14.9 (Me), 24.8 (SꢀCH2 ꢀCH2), 51.1
(pzꢀCH2 ꢀCH2), 107.7 (pzꢀCH), 141.1, 152.2 (pzꢀC).
2959ꢁ
1416, d(CH3)s 1302, d(Cꢀ
cmꢃ1): n(Ptꢀ
/
2853, n(Cꢁ
/
C), n(Cꢁ
/
/
Crystal size (mm)
u Range (8)
0.1ꢄ
3.03ꢁ
/
0.1ꢄ
31.50
/
0.2
0.1ꢄ
1.96ꢁ
/
0.1ꢄ
24.89
/
0.2
/
/
/
Reflexions collected:
Total, independent, Rint
Data/restraints/parameters
a/b *
/
/
/
/
9823, 5922, 0.0266 5688, 3146, 0.0287
5381, 0, 243
1
3146, 0, 297
/
0.0413, 2.6258
0.0370, 0.0902
0.0487, 0.0975
0.0487, 1.3308
0.0392, 0.0969
0.0577, 0.1061
/
/
Final R1, wR2
R1 (all data), wR2
/
Residual electron density
ꢃ3
ꢂ
/
0.756, ꢃ
/
0.843
ꢂ
/
0.310, ꢃ0.398
/
/
/
/
˚
(e A
)
/
/
/
/
* The function minimized was aw(jFoj)2ꢃ
/
jFcj ) , where wꢀ
/
2 2
[s2(I)ꢂ
/
(aP)2ꢂ
/
bP]ꢃ1, and Pꢀ
/
(jFoj ꢂ
/
2jFcj )/3.
2
2
3.2.3. Preparation of [NiCl3(Hdeds)] (4)
A solution of 0.256 g (1.1 mmol) of NiCl2×
/6H2O in 20
ml of acetonitrile (blue) was added dropwise to a
solution of 0.168 g (1.1 mmol) of N-(2-mercaptoethyl)-
3,5-dimethylpyrazole in 5 ml of acetonitrile and 2 ml of
triethyl ortoformate. Solution turned into dark brown
colour (dimeric nickel(II) complex). In presence of
oxygen, and after 3 days, solution turned into blue
turquoise and a pale yellow precipitate was formed
(nickel oxide). Precipitate was filtered off and then
solvent was evaporated to give the desired product.
Yield: 0.24 g (96%), C14H23Cl3N4NiS2 (476.54): C 35.29,
H 4.86, N 11.76, S 13.46; Found: C 35.56, H 4.94, N
11.83, S 13.52%. Conductivity (Vꢃ1 cm2 molꢃ1, 1.01
collected with graphite-monochromated Mo Ka radia-
tion. The structures were solved by direct methods using
the SHELXS 97 computer program [28] and refined by
full-matrix least-squares method with a SHELXL 97
computer program [29].
All hydrogen atoms were computed and refined using
a riding model. The final R (on F) factor and vR (on
F2) values, as well as the numbers of parameters refined
and other details concerning the refinement of the
crystal structure are presented in Table 3.
10ꢃ3 M in acetonitrile): 21.4, IR (KBr, cmꢃ1): n(Cꢀ
H)ar 3129, n(CꢀH)al 2967ꢀ2920, n(CꢁC), n(CꢁN)
1592, 1554, d(CH3)as 1462ꢁ1427, d(CH3)s 1292, d(Cꢀ
H)oop 815ꢁ N)as
833. IR (polyethylene, cmꢃ1): n(Niꢀ
484, n(NiꢀCl) 375. UVꢁ
Vis (acetonitrile, 9.8 10ꢃ4 M,
nm), l(o): 616(215).
/
/
/
/
/
/
/
4. Conclusion
/
/
/
/
The ligand N-(2-mercaptoethyl)-3,5-dimethylpyrazole
(Hmed) reacts with Ni(II), Pd(II) and Pt(II) ions to give
new thiolate bridged dinuclear compounds. These com-
plexes contain the anionic [med]ꢃ ligand in a chelating
form, which induces a rigid conformation of the
ethylenic fragment. NMR studies have shown to be
very useful in the determination of the configuration of
ligands in these complexes. This study represent an
important addition to the series of similar structures
established with M(m2-SR)2M cores. Ni(II) complex
3.3. X-ray crystal structure analyses
Suitable crystals for X-ray diffraction experiments of
compounds 2 and 4 were obtained by crystallisation
from CH2Cl2 and acetonitrile, respectively. Data were
collected on a MAR345 diffractometer with Image Plate
detector, using 8-scan technique. Both crystals were

J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ
/
94
93
Longhurst, Acta Crystallogr., Sect. C (Cr. Str. Commun.) 55
(1999) 1436. (f) C.B. Allan, G. Davidson, S.B. Choudhury, Z. Gu,
K. Bose, R.O. Day, M.J. Maroney, Inorg. Chem. 37 (1998) 4166.
(g) S. Brooker, P.D. Croucher, T.C. Davidson, G.S. Dunbar, A.J.
McQuillan, G.B. Jameson, Chem. Commun. (1998) 2131. (h) B.
Kersting, D. Siebert, Inorg. Chem. 37 (1998) 3820. (i) C.R.
Commas, K.L. Jantzi, J.I. Wirgau, T.C. Stauffer, J.W. Kampf,
P.D. Boyle, Inorg. Chem. 37 (1998) 5851. (j) E. Bouwman, R.K.
Henderson, A.K. Powell, J. Reedijk, W.J.J. Smeets, A.L. Spek, N.
Veldman, S. Wocadlo, J. Chem. Soc., Dalton Trans. (1998) 3495.
(k) N.F. Curtis, O.P. Gladhikh, S.L. Heath, K.R. Morgan, Aust.
J. Chem. 51 (1998) 49. (l) S. Brooker, P.D. Croucher, F.M.
Roxburgh, J. Chem. Soc., Dalton Trans. (1996) 3031. (m) S.B.
Choudhury, M.A. Pressler, S.A. Mirza, R.O. Day, M.J. Maroney,
Inorg. Chem. 33 (1994) 4831. (n) A.J. Atkins, A.J. Blake, M.
Schroder, Chem. Commun. (1993) 1062. (o) M. Mikuriya, M.
Handa, S. Shigematsu, S. Funaki, T. Fujii, H. Okawa, K.
Toriumi, T. Koshiba, H. Terauchi, Bull. Chem. Soc. Jpn 66
(1993) 1104. (p) M. Mikiruya, S. Kida, I. Murase, Bull. Chem.
Soc. Jpn 60 (1987) 1180. (q) T.B. Vance, L.B. Warner, K. Seff,
Inorg. Chem. 16 (1977) 2106.
[NiCl(med)]2 can be oxidised in acetonitrile solution
leading to a new complex with an unique NiCl3N core.
We expect to find further exciting reactivity of 2 with
other substrates to permit study of the hemilabile
character of the ligand.
5. Supplementary material
Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC 196720 (2),
CCDC 196721 (4). These data can be obtained free of
charge at www: http://www.ccdc.cam.ac.uk/conts/retrie-
ving.html [or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (internat.) ꢂ44-1223-336-033; e-mail: depos-
/
[6] di(thiolate)-bridged Pd/Pd systems see: (a) G. Sa´nchez, J.L.
Serrano, M.C. Ram´ırez de Arellano, J. Pe´rez, G. Lo´pez, Poly-
hedron 19 (2000) 1395 (b) B. Kersting, Eur. J. Inorg. Chem. 37
it@ccdc.cam.ac.uk].
(1998) 1071. (c) H. Barrera, J.M. Vinas, M. Font-Altaba, X.
˜
Acknowledgements
Solans, Polyhedron 4 (1985) 2027. (d) X. Solans, M. Font-Altaba,
J.L. Brianso´, J. Sola, J. Suades, H. Barrera, Acta Crystallogr.,
Sect C (Cr. Str. Commun.) 39 (1983) 1653.
Supports by the Ministerio de Educacio´n y Cultura of
Spain (Project BQU2000-0238 and grant to J.G.) are
gratefully acknowledged.
[7] di(thiolate)-bridged Pt/Pt systems see: (a) K.A. Mitchell, C.M.
Jensen, Inorg. Chem. 34 (1995) 4441. (b) K.A. Mitchell, C.M.
Jensen, Inorg. Chem. 32 (1993) 2608. (c) M. Capdevila, W. Clegg,
P. Gonza´lez-Duarte, I. Mira, J. Chem. Soc., Dalton Trans. (1992)
173. (d) J.A. Ayllo´n, P. Gonza´lez-Duarte, C. Miravitlles, E.
Molins, J. Chem. Soc., Dalton Trans. (1990) 1793. (e) C.E. Briant,
C.J. Gardner, T.S.A. Hor, N.D. Howells, D.M.P. Mingos, J.
Chem. Soc., Dalton Trans. (1984) 2645.
References
[1] (a) S. Brooker, Coord. Chem. Rev. 222 (2001) 33;
(b) J.G. Wright, M.J. Natan, F.M. McDonnell, D.M. Ralston,
T.V. O’Halloran, Prog. Inorg. Chem. 38 (1990) 323;
(c) P.J. Blower, J.R. Dilworth, Coord. Chem. Rev. 76 (1987) 121;
(d) R.H. Holm, Chem. Rev. 10 (1981) 455.
[8] M. Mirukiya, M. Handa, S. Shigematsu, S. Funaki, T. Fujii, H.
Okawa, K. Toriumi, T. Koshiba, H. Teranchi, Bull. Chem. Soc.
Jpn 66 (1993) 1104.
[9] A. Volbeda, M.H. Charon, C. Piras, E.C. Hatchikion, M. Frey,
J.C. Fontecilla-Camps, Nature 373 (1995) 580.
[2] (a) J. Arnold, Prog. Inorg. Chem. 43 (1995) 353;
(b) M.G. Kanatzidis, D. Coucovanis, J. Am. Chem. Soc. 108
(1986) 337;
[10] (a) I.H. Krakoff, Cancer Treat. Rep. 63 (1979) 1523;
(b) M. Dentro, F.C. Luft, N.M. Yum, S.D. Williams, L.H.
Einhorn, Cancer 41 (1978) 1274;
(c) I.G. Dance, Polyhedron 5 (1986) 1037;
(d) A.D. Watson, C.h. Pulla Rao, J.R. Dorfman, R.H. Holm,
Inorg. Chem. 24 (1985) 2820;
(c) K.A. Mitchell, C.M. Jensen, Inorg. Chem. 34 (1995) 4441.
[11] (a) E.L.M. Lempers, J. Reedijk, Inorg. Chem. 29 (1990) 1880;
(b) C. Dedon, R.F. Borch, Biochem. Pharmacol. 36 (1978) 1955.
[12] (a) G. Esquius, J. Pons, R. Ya´n˜ez, J. Ros, R. Mathieu, B.
Donnadieu, N. Lugan, Eur. J. Inorg. Chem. (2002) 2999;
(b) R. Mathieu, G. Esquius, N. Lugan, J. Pons, J. Ros, Eur. J.
Inorg. Chem. (2001) 2683;
(e) K.S. Hagen, R.H. Holm, Inorg. Chem. 23 (1984) 418;
(f) D. Coucovanis, Acc. Chem. Res. 14 (1981) 201.
[3] (a) T. Beissel, T. Glaser, F. Kesting, K. Wieghardt, B. Nuber,
Inorg. Chem. 35 (1996) 3936;
(b) T. Beissel, F. Birkelbach, E. Bill, T. Glaser, F. Kesting, C.
Krebs, T. Weyhermuller, K. Wieghardt, C. Butzlaff, A.X.
¨
(c) G. Esquius, J. Pons, R. Ya´nez, J. Ros, J. Organomet. Chem.
˜
Trautwein, J. Am. Chem. Soc. 118 (1996) 12376.
[4] (a) B. Krebs, E. Henkel, Angew. Chem., Int. Ed. Engl. 30 (1991)
769;
619 (2001) 14;
(d) G. Esquius, J. Pons, R. Ya´nez, J. Ros, X. Solans, M. Font-
˜
Bard´ıa, J. Organomet. Chem. 605 (2000) 226;
(b) I.G. Dance, R.G. Garbutt, M.L. Scudder, Inorg. Chem. 29
(1990) 1571.
(e) G. Esquius, J. Pons, R. Ya´nez, J. Ros, X. Solans, M. Font-
˜
Bard´ıa, Acta Crystallogr. C58 (2002) 133.
[13] (a) A. Boixassa, J. Pons, A. Virgili, X. Solans, M. Font-Bard´ıa, J.
Ros, Inorg. Chim. Acta 340 (2002) 49;
[5] di(thiolate)-bridged Ni/Ni systems see: (a) S. Brooker, G.B.
Caygill, P.D. Croucher, T.C. Davidson, D.L.J. Clive, S.R.
Magnson, S.P. Cramer, C.Y. Raltson, J. Chem. Soc., Dalton
Trans. (2000) 3113. (b) S. Brooker, P.D. Croucher, T.C.
Davidson, G.S. Dunbar, C.U. Beck, S. Subramanian, Eur. J.
Inorg. Chem. (2000) 169. (c) B. Kersting, G. Steinfeld, J.
Hausmann, Eur. J. Inorg. Chem., (1999) 179. (d) C.A. Grapper-
haus, J.A. Bellefeuille, J.H. Reibenspies, M.Y. Darensbourg,
Inorg. Chem. 38 (1999) 3698. (e) S.C. Davies, D.L. Hughes, S.
(b) A. Boixassa, J. Pons, X. Solans, M. Font-Bard´ıa, J. Ros,
Inorg. Chim. Acta 346 (2003) 151.
´
[14] R. Tribo´, J. Pons, R. Ya´nez, J.F. Piniella, A. .Alvarez-Larena, J.
˜
Ros, Inorg. Chem. Commun. 3 (2000) 545.
[15] J. Garc´ıa-Anto´n, J. Pons, X. Solans, M. Font-Bard´ıa, J. Ros, Eur.
J. Inorg. Chem. (2002) 3319.

94
J. Garc´ıa-Anto´n et al. / Inorganica Chimica Acta 355 (2003) 87ꢁ94
/
[16] E. Bouwman, P. Evans, R.A.G. de Graaf, H. Kooijman, R.
Poinsot, P. Rabu, J. Reedijk, A.L. Spek, Inorg. Chem. 34 (1995)
6302.
(1999) 179;
(c) M. Handa, M. Mikuriya, Z.J. Zhone, H. Okawa, S. Kida, Bull.
Chem. Soc. Jpn 61 (1988) 3883.
[17] S. Komiya, Synthesis of Organometallic Compounds: A Practical
Guide, Wiley, New York, USA, 1997.
[23] (a) D. Sutton, Electronic Spectra of Transition Metal Complexes,
McGraw-Hill, London, UK, 1975;
[18] F.A. Cotton, Inorganic Synthesis 13 (1972) 52.
[19] (a) W.J. Geary, Coord. Chem. Rev. 7 (1971) 81;
(b) L.K. Thompson, F.L. Lee, E.J. Gabe, Inorg. Chem. 27 (1988)
39.
(b) J.C. Bailar, H.J. Emeleus, S.R. Nyttorm, A.F.T. Dickenson,
Comprehensive Inorganic Chemistry, Pergamon Press, London,
UK, 1973.
[24] E. Pretsh, T. Clerc, J. Seibl, W. Simon, Tables of Determination
1
[20] (a) E. Pretsh, T. Clerc, J. Seibl, W. Simon, Tables of Determina-
tion of Organic Compounds. 13C-NMR, 1H-NMR, IR, MS, UV/
VIS, Chemical Laboratory Practice, Springer, Berlin, Germany,
1989;
of Organic Compounds. 13C-NMR, H-NMR, IR, MS, UV/VIS,
Chemical Laboratory Practice, Springer, Berlin, Germany, 1989.
[25] F.H. Allen, O. Kennard, Chem. Des. Autom. News 8 (1993) 31.
[26] S. Buchler, F. Meyer, A. Jacobi, P. Kircher, L. Zsolnai, Z.
Naturforsch 54b (1999) 1295.
(b) D.H. Williams, I. Fleming, Spectroscopic Methods in Organic
Chemistry, McGraw-Hill, London, UK, 1995.
[27] W.L. Driessen, R.M. de Vos, A. Etz, J. Reedijk, Inorg. Chim.
Acta 235 (1995) 127.
[21] (a) R.J.H. Clark, G. Natile, U. Belluco, L. Cattalini, C. Filippin,
J. Chem. Soc. (A) (1970) 659;
[28] G.M. Sheldrick, Acta Crystallogr. A46 (1990) 467.
[29] G.M. Sheldrick, SHELXS 97, SHELXL 97, CIFTAB-Program for
(b) K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, Wiley, New York, USA, 1986.
[22] (a) M.A. Halcrow, E. Christon, Chem. Rev. 94 (1994) 2421;
(b) B. Kersting, G. Steinfeld, J. Hausmann, Eur. J. Inorg. Chem.
Crystal Structure Analysis (Release 97-2), Institut fur Anargo-
¨
nische Chemie der Universitat, Tammanstraße 4, 3400 Gottingen,
Berlin, Germany, 1998.
¨
¨