Reactivity of [PdCl(μ-med)]2 with monodentate or bidentate ligands. Structure of the dinuclear complexes [Pd(μ-med)(PPh 3)]2(BF4)2 and [Pd(μ-med)(bpy)] 2(BF4)2. [Hmed=N-(2-mercaptoethyl)-3,5- dimethylpyrazole]

Article abstract of DOI:10.1016/j.ica.2003.08.013

Treatment of the ligand N-(2-mercaptoethyl)-3,5-dimethylpyrazole with [Pd(CH₃COO)₂]₃ and reaction of [PdCl(μ-med)]₂ with pyridine (py) or triphenylphosphine (PPh ₃) in the presence of AgBF₄ produced the following complexes: [Pd(CH₃COO)(μ-med)]₂, [Pd(μ-med)(py)] ₂(BF₄)₂ and [Pd(μ-med)(PPh ₃)]₂(BF₄)₂. Similar reactions carried out with 2,2′-bipyridine (bpy) or 1,3-bis(diphenylphosphino) propane (dppp) produced [Pd(μ-med)(bpy)]_x(BF₄) _x (x=1 or 2) and [Pd(μ-med)(dppp)]_x(BF ₄)_x (x=1 or 2). Treatment of [Pd(μ-med)(bpy)] _x(BF₄)_x with [PdCl₂(CH ₃CN)₂] produced [Pd₃Cl₂(μ-med) ₂(bpy)₂](BF₄)₂. Treatment of [Pd(μ-med)(dppp)]_x(BF₄)_x with [PdCl ₂(CH₃CN)₂] produced a mixture of [Pd(μ-Cl)(dppp)]₂(BF₄)₂ and [Pd(μ-med)₂(dppp)]²⁺. X-ray crystal structures of [Pd(μ-med)(PPh₃)]₂(BF₄) ₂·2CH₃CN and [Pd(μ-med)(bpy)]₂(BF ₄)₂·0.5CH₃OH are presented.

Full text of DOI:10.1016/j.ica.2003.08.013

Inorganica Chimica Acta 357 (2004) 571–580
www.elsevier.com/locate/ica
Reactivity of [PdCl(l-med)]2 with monodentate or bidentate
ligands. Structure of the dinuclear complexes
[Pd(l-med)(PPh3)]2(BF4)2 and [Pd(l-med)(bpy)]2(BF4)2.
[Hmed ¼ N-(2-mercaptoethyl)-3,5-dimethylpyrazole]
b
a
a,
b
*
ꢀ
ꢀ
ꢁ
Jordi Garcıa-Anton , Josefina Pons , Xavier Solans , Merce Font-Bardia ,
a
Josep Ros
a
Departament de Quꢀımica, Universitat Autoꢁnoma de Barcelona, Facultat de Cieꢁncies, Bellaterra-Cerdanyola, Barcelona 08193, Spain
b
Cristal.lografia, Mineralogia i Dipoꢁsits Minerals, Universitat de Barcelona, Martꢀı i Franqueꢁs s/n, Barcelona 08028, Spain
Received 16 August 2003; accepted 19 August 2003
Abstract
Treatment of the ligand N-(2-mercaptoethyl)-3,5-dimethylpyrazole with [Pd(CH3COO)2]3 and reaction of [PdCl(l-med)]2 with
pyridine (py) or triphenylphosphine (PPh3) in the presence of AgBF4 produced the following complexes: [Pd(CH3COO)(l-med)]2,
[Pd(l-med)(py)]2(BF4)2 and [Pd(l-med)(PPh3)]2(BF4)2. Similar reactions carried out with 2,20-bipyridine (bpy) or 1,3-bis(di-
phenylphosphino)propane (dppp) produced [Pd(l-med)(bpy)]x(BF4)x (x ¼ 1 or 2) and [Pd(l-med)(dppp)]x(BF4)x (x ¼ 1 or 2).
Treatment of [Pd(l-med)(bpy)]x(BF4)x with [PdCl2(CH3CN)2] produced [Pd3Cl2(l-med)2(bpy)2](BF4)2. Treatment of [Pd
(l-med)(dppp)]x(BF4)x with [PdCl2(CH3CN)2] produced a mixture of [Pd(l-Cl)(dppp)]2(BF4)2 and [Pd(l-med)2(dppp)]2þ. X-ray
crystal structures of [Pd(l-med)(PPh3)]2(BF4)2 ꢀ 2CH3CN and [Pd(l-med)(bpy)]2(BF4)2 ꢀ 0.5CH3OH are presented.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Palladium; N ligand; S ligand
1. Introduction
In recent years we have studied and reported the
synthesis and characterisation of ligands based on the
pyrazolyl group and another group containing N
(amine) [4], P (phosphine) [5], O (alcohol or ether) [6]
and S (thioether) [7] atoms.
The complexation of these ligands with Ru(II) [5],
Rh(I) [4,5], Pd(II) [6,7] and Pt(II) [6,7] was also studied,
but only the complexes of Rh(I) with pyrazole–amine
[4a,4e] or pyrazole–ether [6d] ligands and the Pd(II) and
Pt(II) complexes of the pyrazole–thioether ligands [7]
had hemilabile properties.
This paper continues a recent study based on the
coordination of the ligand N-(2-mercaptoethyl)-3,5-
dimethylpyrazole (Hmed) when treated with group 10
metal salts [8]. In the previous paper, the synthesis and
characterisation of [MCl(l-med)]2 (M ¼ Ni(II), Pd(II)
and Pt(II)) is reported. These complexes consist of
dimeric units in which two-thiolate groups bridge two
The term ‘‘hemilabile ligand’’ – first introduced by
Jeffrey and Rauchfuss [1] – refers to polydentate ligands
that contain at least two different types of chemical
functionalities that bind to metal centres. They must
contain at least one substitutionally labile donor group
while the other group remains firmly bound to the metal
centre [2]. Their interest lies in their potential applica-
tion in catalysis.
Pyrazole-based ligands are suitable models on which
to study hemilabile properties since they are relatively
easy to obtain and we can modulate their steric and
electronic properties [3].
* Corresponding author. Tel.: +34-93581-2895; fax: +34-93581-3101.
E-mail address: Josefina.Pons@uab.es (J. Pons).
0020-1693/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.08.013

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J. Garcıa-Anton et al. / Inorganica Chimica Acta 357 (2004) 571–580
N
S
CH3COO
N
Hmed
Pd
[Pd(CH COO) ]
CH COOH
3
6
+
2 3
3
Pd
+ 6
OOCCH3
2
3
N
N
S
[1]
Scheme 1.
+
+
metallic centres and each pyrazolyl group coordinates
one of these metallic cations.
N
N
N
N
S
S
4
Pd
2
Pd
Here we extend the study of the coordinative prop-
erties of the Hmed ligand to Pd(II). Treatment of the
ligand with [Pd(CH3COO)2]3 and reaction of [PdCl
(l-med)]2 with pyridine (py) or triphenylphosphine
(PPh3) in the presence of AgBF4 produced the following
complexes: [Pd(CH3COO)(l-med)]2 [1], [Pd(l-med)
(py)]2(BF4)2 [2](BF4)2 and [Pd(l-med)(PPh3)]2(BF4)2
[3](BF4)2. Similar reactions with 2,20-bipyridine (bpy) or
1,3-bis(diphenylphosphino)propane (dppp) produced
[Pd(l-med)(bpy)]x(BF4)x (x ¼ 1, [4a](BF4); x ¼ 2,
[4b](BF4)2) and [Pd(l-med)(dppp)]x(BF4)x (x ¼ 1,
[5a](BF4); x ¼ 2, [5b](BF4)2). X-ray crystal structures of
[3](BF4)2 ꢀ 2CH3CN and [4b](BF4)2 ꢀ 0.5CH3OH are
presented. Treatment of [4](BF4)x with [PdCl2
N
N
Ph2P
PPh2
[5a]+
[4a]+
2+
2+
N
N
Ph2P
PPh2
S
N
N
N
N
Pd
Pd
Pd
Pd
2
N
N
N
S
N
S
N
S
N
Ph2P
PPh2
[4b]2+
[5b]2+
[PdCl2(CH3CN)2]
- 2 CH3CN
2 [PdCl2(CH3CN)2]
- 4 CH3CN, 2 Cl-
Ph2
P
Pd
Ph2
2+
Cl
Cl
P
N
2+
Pd
S
S
Pd
[7]2+
N
N
P
P
Pd
N
Ph2
Ph2
N
N
Cl
N
2+
2+
+
Pd
N
N
N
N
N
2+
S
Pd Pd
S
S
Pd Pd
S
Ph3P
Cl
N
[6]2+
N
N
Ph2
P
N
N
N
N
PPh3
S
N
[2]2+
[3]2+
Pd Pd
2
N
N
S
P
Ph2
2 py, 2 AgBF4
- 2 AgCl
2 PPh3, 2 AgBF4
- 2 AgCl
[8]2+
N
N
S
Pd Pd
S
Cl
Scheme 3.
N
N
Cl
2 bpy, 2 AgBF4
- 2 AgCl
2 CH3CN, 2 AgBF4
- 2 AgCl
(CH3CN)2] produced [Pd3Cl2(l-med)2(bpy)2](BF4)2
[6](BF4)2. Treatment of [5](BF4)x with [PdCl2
(CH3CN)2] produced a mixture of [Pd(l-Cl)(dppp)]2
(BF4)2 [7](BF4)2 and [Pd(l-med)2(dppp)]2þ [8]2þ
(Schemes 1–3).
2+
+
N
N
CH3CN
S
S
S
N
N
Pd
Pd
2
Pd
N
N
N
N
NCCH3
[4a]+
2 dppp
2+
+
2. Results and discussion
N
N
N
N
N
N
Pd
Pd
S
N
N
S
N
S
N
2
Pd
The Hmed was synthesised as described by Bouwman
et al. [9]. Complexes [PdCl2(CH3CN)2] [10] and [PdCl(l-
med)]2 [8] were synthesised as described elsewhere.
Treatment of the ligand with [Pd(CH3COO)2]3 in
acetonitrile gave [Pd(CH3COO) (l-med)]2 [1]. Treat-
ment of [PdCl(l-med)]2 with AgBF4 in the presence of
pyridine or triphenylphosphine yielded [Pd(l-med)(py)]2
(BF4)2 [2](BF4)2 and [Pd(l-med)(PPh3)]2(BF4)2 [3]
(BF4)2. These proposed formulas were corroborated by
elemental analyses.
Ph2P
PPh2
[5a]+
[4b]2+
2+
Ph2P
PPh2
N
N
Pd
N
N
S
S
Pd
Ph2P
PPh2
[5b]2+
Scheme 2.

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573
Conductivity in acetonitrile for [1] (2 Xꢁ1 cm2 molꢁ1
)
bands attributable to m(Pd–Npz)as between 459 and 450
cmꢁ1 and m(Pd–S) between 301 and 280 cmꢁ1. Bands
attributable to m(Pd–O) at 511 cmꢁ1 for [1] and m(Pd–P)
at 310 cmꢁ1 for [3](BF4)2 were also assigned.
shows that the complex is a nonelectrolyte. Conductivity
values in acetonitrile for complexes [2](BF4)2 and
[3](BF4)2 (278 and 263 Xꢁ1 cm2 molꢁ1, respectively) are
in agreement with 2:1 electrolytes. The reported values
for 10ꢁ3 M solutions of nonelectrolyte complexes are
lower than 120 Xꢁ1 cm2 molꢁ1 in acetonitrile, while the
range of conductivity values for 10ꢁ3 M solutions of 2:1
electrolyte compounds in acetonitrile is between 220 and
300 Xꢁ1 cm2 molꢁ1 [11].
IR spectra of complexes [1]–[3](BF4)2 are similar to
that of [PdCl(l-med)]2, the most characteristic bands
being those attributable to the pyrazolyl group:
m(C@C)ar and m(C@N)ar between 1553 and 1551 cmꢁ1
The absence of the m(S–H) band, found in the free ligand
spectrum at 2543 cmꢁ1, shows that the ligand Hmed acts
as a thiolate (med) when complexed. The IR spectrum of
[1] shows the absorption bands assigned to the asym-
metric and symmetric m(OCO) stretching modes. It dis-
plays one mas(OCO) band at 1617 cmꢁ1 and one ms(OCO)
band at 1370 cmꢁ1, separated by D ¼ masðOCOÞ ꢁ
msðOCOÞ ¼ 247 cmꢁ1. This D value suggests the presence
of unidentate acetate groups in compound [1] [12].
IR spectrum of [2](BF4)2 presents a band attributable
to m(C@C)py and m(C@N)py at 1606 cmꢁ1. IR spectra of
[2](BF4)2 and [3](BF4)2 present bands that were assigned
to m(B–F) at 1057 and 1058 cmꢁ1, respectively [13].
The IR spectra of the complexes in 500–100 cmꢁ1
region were also studied [14]. In all cases they show
The 1H and 13C{1H} NMR spectra of complexes [1]–
[3](BF4)2 show the signals of coordinated ligands [15].
Spectra of [1] and [3](BF4)2 were recorded in CDCl3 and
spectra of [2](BF4)2 were recorded in [D3] acetonitrile.
1H NMR spectra show, for complexes [1]–[3](BF4)2,
four groups of doublets of doublets of doublets which
can be assigned to a single hydrogen of the N–CH2–
CH2–S fragment each. This happens because the two
protons of each CH2 are diastereotopic, owing to the
rigid conformation of the ligand when it is complexed.
HMQC spectra of [1]–[3](BF4)2 were used to assign 7-
H protons to the two doublets of doublets of doublets of
lower d and 6-H protons to those of higher d (Fig. 1).
We obtained a set of coupling constants for com-
plexes [1] and [2](BF4)2 with the aid of the gNMR
program [16]. All these results are reported in Section 4.
Fig. 2 shows the experimentally determined and simu-
lated spectra for [1]. Coupling constants for complex
[3](BF4)2 could not be obtained due to the broadness of
the bands.
.
These spectra suggest a coordination of the thiolate
ligand (med) similar to that found for [PdCl(l-med)]2 in
which two thiolate ligands N-(2-mercaptoethyl)-3,5-
dimethylpyrazolate (med) bridge two metallic centres
and the pyrazolyl groups are bonded to one palladium
2 Me
CH3COO
pz-CH
1-H
2-H
2-H
(ppm)
0
2 Me
CH3COO
2-C
40
1-C
80
pz-CH
120
160
200
2 pz-CH
CH3COO
(ppm)
8.0
6.0
4.0
2.0
0.0
Fig. 1. The 250 MHz 2D HMQC spectrum of [Pd(CH3COO)(l-med)]2 [1] and the numbering for the complexes [1]–[3](BF4)2.

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J. Garcıa-Anton et al. / Inorganica Chimica Acta 357 (2004) 571–580
Fig. 2. The 400-MHz 1H NMR and gNMR simulated spectra for the NCH2CH2S fragment of [Pd(CH3COO)(l-med)]2 [1].
each [8]. The remaining coordination site for each pal-
ladium atom (occupied by the chloride ion in [PdCl
(l-med)]2) is now occupied in [1]–[3](BF4)2 by an un-
identate acetate, a pyridine or a triphenylphosphine,
respectively.
Further evidence of the N,S:S0 coordination can be
seen in the X-ray crystal structure of [3](BF4)2 ꢀ
2CH3CN.
the mean coordination plane which contains the Pd
ꢂ
ꢂ
0.035(3) A for N(1).
atom, which are )0.036(1) A for the sulfur atom and
The two planar PdNPS2 units are joined via two
bridging thiolate ligands forming a four-membered ring,
which is flat, with Pdꢀ ꢀ ꢀPd and Sꢀ ꢀ ꢀS distances of
ꢂ
3.4159(5) and 3.1729(4) A, respectively. Bridging angle
for Pd–S–Pd(a) is 94.23(3)°.
The structure of [3](BF4)2 ꢀ 2CH3CN (Fig. 3) consists
Pd–N distances are slightly shorter than those re-
ported for dinuclear complexes with PdNS2X cores (N
amine, S bridging thiolate and X chloride or nitrogen
atom) [17] and Pd–P and Pd–S distances are similar to
those reported for dinuclear complexes with PdPS2X
(P ¼ PPh3, S bridging thiolate and X chloride or thio-
late) [18] and PdNS2X (N amine, S bridging thiolate and
X chloride or nitrogen) [17] cores, respectively.
The amino–thiolate ligand acts as a bidentate chelate
(as well as bridging ligand), forming a Pd–S–C–C–N–N
ring. This ring has skew-boat conformation. Bite angle
N(1)–Pd–S is 84.12(9)°.
of dimeric cationic units of [Pd(l-med)(PPh3)]22þ, BF4
anions and solvent molecules (CH3CN). The structure
contains an inversion centre.
ꢁ
Each palladium atom is coordinated by two thiolate-
bridging sulfurs (in anti conformation), one pyrazole
nitrogen and one triphenylphosphine ligand in a dis-
torted square-planar geometry. Table 1 lists selected
bond distances and bond angles for the cation [3]2þ
.
Tetrahedral distortion of the square-planar geometry
can be observed in the largest deviations with respect to
The distortion of the skew-boat in the ring Pd–N(1)–
1
N(2)–C(6)–C(7)–S is DCS(N(1)–N(2)) ¼ 29.8(4)° .
C11
C10
C9
To examine the influence of the ligands that replace
the chloride ion in [PdCl(l-med)]2, we exchanged the
chloride ion by bidentate chelating ligands 2,20-bipyri-
dine and 1,3-bis(diphenylphosphino)propane. In con-
trast, use of the same reaction conditions with the ligand
1,2-bis(diphenylphosphino)ethane (dppe) gave decom-
position products.
C12
C8
C23
C13
C22
C21
C24
C25
C20
C19
P
Pd
C14
C15
C18
Treatment of [PdCl(l-med)]2 with AgBF4 in the pres-
ence of 2,20-bipyridine produced a complex whose elec-
S
C17
N1
C2
C7
C16
C6
C1
N2
1
vffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
u
C4
C3
m
P
u
u
t
2
ð/i þ /0Þ
i
C5
i¼1
DCs ¼
m
2þ
Fig. 3. ORTEP drawing of [Pd(l-med)(PPh3)]2 cation ([3]2þ) (293 K
determination) showing the atom numbering scheme. Fifty percent
probability amplitude displacement ellipsoids are shown.
where m is the equivalent torsion angles and /i þ /0 is the torsion
i
angles related to the considered plane [19].

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575
Table 1
C33
Selected bond lengths (A) and angles (°) for [3] and [4b]2þ with es-
2þ
ꢂ
C29
C3
timated standard deviations (esds) in parentheses
N7
C31
[3]2þ
[4b]2þ
C19
C28
C32
Pd–N(1)
Pd–P
Pd–S
2.060(3)
Pd(1)–N(1)
Pd(1)–N(2)
2.064(4)
2.078(3)
N8
C10
Pd1
C9
C18
C20
N4
2.2936(9)
2.2972(10)
2.3646(9)
C8
C7
S2
Pd(1)–S(1)
Pd(1)–S(2)
2.2841(10)
2.2906(11)
2.072(3)
C17
C34
Pd–S(a)
Pd2
C16
C15
Pd(2)–N(3)
Pd(2)–N(4)
N2
C21
S1
C6
2.072(4)
N3
C14
Pd(2)–S(2)
Pd(2)–S(1)
Pd(1)–Pd(2)
2.2854(10)
2.2872(11)
3.4159(5)
80.13(15)
99.21(10)
176.75(10)
178.60(9)
98.66(12)
81.97(4)
C22
C4
C3
N1
C1
C5
C26
C23
N5
C11
N(1)–Pd–P
N(1)–Pd–S
P–Pd–S
99.24(9)
169.02(9)
90.17(3)
84.12(9)
171.21(3)
85.77(3)
94.23(3)
N(1)–Pd(1)–N(2)
N(1)–Pd(1)–S(1)
N(2)–Pd(1)–S(1)
N(1)–Pd(1)–S(2)
N(2)–Pd(1)–S(2)
S(1)–Pd(1)–S(2)
N(3)–Pd(2)–N(4)
N(3)–Pd(2)–S(2)
N(4)–Pd(2)–S(2)
N(3)–Pd(2)–S(1)
N(4)–Pd(2)–S(1)
S(2)–Pd(2)–S(1)
C13
C12
N6
C2
C24
N(1)–Pd–S(a)
P–Pd–S(a)
S–Pd–S(a)
Pd–S–Pd(a)
C25
C27
80.09(13)
175.18(10)
99.54(10)
98.11(10)
176.56(10)
82.01(4)
2þ
Fig. 4. ORTEP drawing of [Pd(l-med)(bpy)]2 cation [4b]2þ (293 K
determination) showing the atom numbering scheme. Fifty percent
probability amplitude displacement ellipsoids are shown.
The two planar PdN2S2 units are joined via two
bridging thiolate ligands forming a four-membered ring,
which is CR form, with Pdꢀ ꢀ ꢀPd and Sꢀ ꢀ ꢀS distances
trospray mass spectrum is in accordance with the pro-
posed formula [Pd(l-med)(bpy)](BF4) [4a](BF4). The 1H
NMR spectrum of this complex in CDCl3 is similar to
those of [1]–[3](BF4)2. Four groups of broad doublets of
doublets of doublets can be assigned to each H from the
N–CH2–CH2–S chain. This means that the ligand is rigid
when complexed to the metallic centre. The ligand (med)
is coordinated through the thiolate and pyrazolyl groups,
but, in contrast to what happens in [1]–[3] (BF4)2, the
complex is mononuclear in [4a](BF4) (Scheme 2).
To explore how the pyrazole–thiolate ligand coordi-
nates the metallic centre, [4a](BF4) was recrystallised in
a mixture of dichloromethane and methanol (1:1) and,
surprisingly, monocrystals of [Pd(l-med)(bpy)]2 (BF4)2 ꢀ
0.5CH3OH [4b](BF4)2 ꢀ 0.5CH3OH were obtained. These
were structurally characterised by X-ray crystallogra-
phy. The structure (Fig. 4) consists of cationic units of
[Pd(l-med)(bpy)]22þ, BF4ꢁ anions and solvent molecules
(methanol).
ꢂ
ꢂ
3.4369(5) A and 3.0002(17) A, respectively. The dihedral
angle between the planes Pd(1)–S(1)–Pd(2) and Pd(1)–
S(2)–Pd(2) is 8.16(5)°. Bridging angles for Pd(1)–S(1)–
Pd(2) and Pd(1)–S(2)–Pd(2) are 97.50(4)° and 97.37(4)°,
respectively.
2,20-Bipyridine ligands act as bidentate chelates
forming two Pd–N–C–C–N rings. The Pd(1)–N(1)–
C(5)–C(6)–N(2) ring is twisted on Pd(1)–N(1) bond
whereas the Pd(2)–N(3)–C(15)–C(16)–N(4) ring is flat.
Bite angles N(1)–Pd(1)–N(2) and N(3)–Pd(2)–N(4) are
80.13(15)° and 80.09(13)°, respectively. These angles are
similar to those reported for complexes with chelating
2,20-bipiridines [20].
The distortion of the five-membered rings is
DCS(Pd(1)–N(1)) ¼ 9.8(5)° and DCS(Pd(2)–N(3)) ¼
5.2(4)° for Pd(1)–N(1)–C(5)–C(6)–N(2) and Pd(2)–
N(3)–C(15)–C(16)–N(4), respectively.
When the crystals of [4b](BF4)2 ꢀ 0.5CH3OH were
redissolved in chloroform or dichloromethane, [4a]þ was
again obtained in solution. Varying the temperature we
could not observe the formation of [4b]2þ in solution.
1,3-Bis(diphenylphosphino)propane reacted with
[Pd(l-med)(CH3CN)]2(BF4)2 (generated in situ from the
reaction of [PdCl(l-med)]2, acetonitrile and AgBF4 in a
mixture of dichloromethane and methanol) to give two
complexes in a 1:1 ratio. The 31P{1H} NMR spectrum
of the mixture shows two doublets centred at 0.2 and
13.5 ppm with the same coupling constant (2J ¼ 51:5
Hz, assigned to [Pd(l-med)(dppp)]þ [5a]þ) and a sin-
Each palladium atom is coordinated by two thiolate-
bridging sulfurs from two pyrazole ligands (in syn con-
formation) and two nitrogens of 2,20-bipyridine in a
distorted square-planar geometry. The pyrazole groups
are not coordinated to the metal centre. Table 1 lists
selected bond distances and bond angles for the cation
[4b]2þ
.
Tetrahedral distortion of the square-planar geometry
can be observed in the largest deviation with respect to
the mean coordination planes, which contain Pd atoms.
ꢂ
These deviations are ꢂ 0.025(5) A for the nitrogen atoms
ꢂ
and ꢂ 0.022(1) A for the sulfur atoms with respect to
2þ
ꢂ
glet at 10.2 ppm (assigned to [Pd(l-med)(dppp)]2
Pd(1), and ꢂ 0.018(4) A for the nitrogen atoms and
ꢂ
ꢂ 0.016(1) A for the sulfur atoms with respect to Pd(2).
[5b]2þ). These data are in agreement with [5a]þ being a

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576
mononuclear species of Pd(II) with dppp and the thio-
late ligand (med) chelating the metallic centre as in
[4a]þ and [5b]2þ a dinuclear compound similar to [4b]2þ
(Scheme 2).
mass spectrum are in agreement with the formula [Pd(l-
Cl)(dppp)]2(BF4)2 ([7](BF4)2) (Scheme 3). The cationic
part of this complex had previously been reported by
2ꢁ
ꢁ
Pelzer et al. [22] but with SO4 instead of BF4
.
To confirm the presence of these two species, an
electrospray mass spectrum of the mixture was per-
formed (solvent acetonitrile). Sample was measured at
573 K. Surprisingly, only the mononuclear species
([5a]þ) was observed, even though an enhanced resolu-
tion technique was applied. This indicated a temperature
dependent dynamic equilibrium between the two species.
Therefore, we performed variable-temperature NMR
studies of the mixture in [D3] acetonitrile. At 343 K, the
initial ratio 1:1 ([5a]þ:[5b]2þ) turned into a 4:1 ratio.
When temperature was returned to 298 K, the initial
ratio was restored.
The other complex (d ¼ 7:5 ppm in the 31P{1H}
NMR spectrum) could not be obtained as a pure
product. From the electrospray mass spectrum of a so-
lution in which it is the majority compound, it was
possible to assign it to [Pd2(l-med)2(dppp)]2þ [8]2þ. The
1H NMR spectrum of this species shows the four groups
of broad doublets of doublets of doublets typical of N,S
coordination. The proposed structure is illustrated in
Scheme 3.
3. Conclusion
As the equilibrium was displaced towards [5a]þ when
the temperature was raised, we attempted to obtain pure
[5b]2þ at low temperatures. When a saturated solution of
[5a]þ and [5b]2þ in a mixture of dichloromethane and
methanol was cooled to 243K, we obtained [5b](BF4)2
(0.11 g, 83% yield) as dark yellow microcrystals.
The 31P{1H} NMR spectrum of pure [5b]2þ in
CD2Cl2 returned to that of the initial mixture of [5a]þ
and [5b]2þ after approximately 30 min.
The thiolate ligand N-(2-mercaptoethyl)-3,5-dim-
ethylpyrazolate (med) forms dinuclear Pd(II) units with
the general formula [Pd(l-med)X]2, X being a monod-
entate (chloride, acetate, pyridine, triphenylphosphine)
or bidentate (2,20-bipiridine (bpy), 1,3-bis(diph-
enylphosphino)propane (dppp)) ligand. These dimeric
units can be neutral or charged depending on X.
When X is monodentate, the thiolate group in med
bridges the two Pd atoms and the pyrazolyl group che-
lates one of the metallic centres. When X is bidentate,
two isomers can be formed, and in one of them (the
dinuclear species) the chelate is broken, and the pyraz-
olyl group is uncoordinated. This shows the different
coordinative properties of the thiolate and pyrazolyl
groups. Furthermore, when X is bidentate, another
isomer is formed. In this isomer (a mononuclear spe-
cies), med does not act as a bridging ligand, although it
does chelate the metallic centre through the thiolate and
pyrazolyl groups. When X is dppp, there is a dynamic
equilibrium between the dinuclear and the mononuclear
species. Therefore, the pyrazolyl group coordinates and
de-coordinates the palladium atom in a process that
could be considered as hemilabile.
Treatment of [4b](BF4)2 with [PdCl2(CH3CN)2] pro-
duced a complex whose elemental analyses are consis-
tent with the formula [Pd3Cl2(l-med)2(bpy)2](BF4)2
([6](BF4)2) (Scheme 3). Conductivity value for this
complex in acetonitrile (266 Xꢁ1 cm2 molꢁ1) corre-
sponds to those of 2:1 electrolytes [11]. The IR spectrum
between 500 and 100 cmꢁ1 shows bands attributable to
m(Pd–N)as(bpy, pz) at 417 cmꢁ1, m(Pd–Cl) at 348 cmꢁ1
1
and m(Pd–S) at 279 cmꢁ1 [14]. The H NMR spectrum
shows four signals corresponding to the NCH2CH2S
chain, as expected for the rigid structure of this complex
(Scheme 3). Although the four signals resemble the
doublets of doublets of doublets found for complexes
[1]–[3](BF4)2, they could not be further studied due to
their broadness. Electrospray mass spectrum of this
complex shows the monocationic unit {[6] ꢀ BF4}þ.
There are four structures reported in the literature on
trinuclear Pd(II) complexes with at least one pyrazolyl
group coordinated to one of the metal centres [21]. The
cores of the metallic centres in the hypothetical structure
of [6](BF4)2 would be two [PdN2S2] and one [PdCl2N2].
The [PdN2S2] core is not found in any of the trinuclear
species described in the literature. However, the
[PdCl2N2] core is found in two of them [21a,21c].
In summary, we have shown that the ligand med,
when complexed to Pd(II), can act as a bridge, a chelate
or a bridging-chelate, depending on the coordinative
environment of the metallic centre.
4. Experimental
4.1. Generals remarks
Treatment of a solution of [5a](BF4)/[5b](BF4)2 with
[PdCl2(CH3CN)2] produced a mixture of two complexes
in a 1:1 ratio, with chemical shifts in the 31P{1H} NMR
spectrum of 7.5 and 12.6 ppm. Recrystallisation of the
mixture with dichloromethane/diethyl ether (1:1) yielded
one of the complexes (d ¼ 12:6 ppm in the 31P{1H} NMR
spectrum), whose elemental analyses and electrospray
Preparations were performed using usual vacuum line
and Schlenk techniques. All reagents were commercial
grade materials and were used without further purifi-
cation. Acetonitrile and dichloromethane were dried
and distilled by standard methods and previously de-
oxygenated in the vacuum line.

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577
We recently reported the preparation of [PdCl(l-
med)]2 [8]. N-(2-Mercaptoethyl)-3,5-dimethylpyrazole
[9] and [PdCl2(CH3CN)2] [10] were prepared according
to the reported methods.
and methanol (10 ml). About 0.025 g (0.32 mmol) of
pyridine was then added, followed immediately by a
solution of 0.051 g (0.26 mmol) of AgBF4 in methanol (2
ml). The reaction was carried out in the dark to prevent
reduction of Ag(I) to Ag(0). After 5 min, stirring was
stopped, and AgCl was filtered off through Celite
pad. Solution had turned from initial orange to bright
yellow. When the volume of resultant solution had been
reduced to roughly 5 ml, the product precipitated as
a yellow solid. This solid was filtered and washed in
dichloromethane.
Analyses (C, N, H, and S) were performed in our
analytical laboratory on a Carlo Erba CHNS EA-1108
instrument. Conductivity measurements were performed
at room temperature in 10ꢁ3 M acetonitrile solutions
employing a Crison, micro CM 2200 conductimeter.
Infrared spectra were recorded from KBr pellets or
polyethylene mulls in the range 4000–100 cmꢁ1 under a
nitrogen atmosphere. The 1H NMR, 13C{1H} NMR,
31P{1H} NMR, HMQC and NOESY spectra were ob-
tained either on a Bruker 250 MHz or Bruker 400 MHz
instrument. 1H NMR and 13C{1H} NMR chemical
shifts (dÞ were determined relative to internal TMS and
are given in ppm. 31P{1H} NMR chemical shifts are
relative to external 85% H3PO4 and are given in ppm.
Mass spectra were obtained with an Esquire 3000 ion
trap mass spectrometer from Bruker Daltonics.
Yield: 0.104 g (93%) – C24H32B2F8 N6Pd2S2 (855.13):
C, 33.71; H, 3.77; N, 9.83; S, 7.50. Found: C, 33.46; H,
3.57; N, 9.60; S, 7.22%. Conductivity (Xꢁ1 cm2 molꢁ1
,
1.03 ꢃ 10ꢁ3 M in acetonitrile): 278 – IR (KBr, cmꢁ1):
m(C–H)ar 3057, m(C–H)al 2927, m(C@C)py, m(C@N)py
1606, m(C@C)pz, m(C@N)pz 1553, d(CH3)as 1454,
d(CH3)s 1382, m(B–F) 1057, d(C–H)oop 758. IR (poly-
1
ethylene, cmꢁ1): m(Pd–N)as(pz, py) 457, m(Pd–S) 280. H
NMR (400 MHz, [D3]-acetonitrile solution) d ¼ 1:63 (s,
6H, Me), 2.22 (s, 6H, Me), 1.55 (ddd, 2H, pz-CH2–
CHH, 2J ¼ 14.6 Hz, 3J ¼ 11.9 Hz, 3J ¼ 2.1 Hz), 2.00
(ddd, 2H, pz-CH2–CHH, 2J ¼ 14.6 Hz, 3J ¼ 1.3 Hz,
3J ¼ 3.9 Hz), 4.53 (ddd, 2H, pz-CHH–CH2, 2J ¼ 15.3
Hz, 3J ¼ 11.9 Hz, 3J ¼ 1.3 Hz), 4.98 (ddd, 2H, pz-CHH–
CH2, 2J ¼ 15.3 Hz, 3J ¼ 2.1 Hz, 3J ¼ 3.9 Hz), 5.98 (s, 2H,
pz-CH), 7.67 (m, 4H, py), 8.13 (m, 2H, py), 8.77 (m, 4H,
py). 13C{1H} NMR (63 MHz, [D3]-acetonitrile solution)
d ¼ 11:9 (Me), 13.6 (Me), 29.4 (S–CH2–CH2), 52.7 (pz-
CH2–CH2), 108.8 (pz-CH), 128.5 (py), 141.8 (py), 145.1
(pz-C), 151.8 (pz-C), 153.1 (py).
4.2. Synthesis of the complexes
4.2.1. [Pd(l-med)(CH3COO)]2 [1]
A
solution of 0.220
g
(0.33 mmol) of
[Pd(CH3COO)2]3 in 10 ml of acetonitrile was added
dropwise to a solution of 0.154 g (0.99 mmol) of N-
mercaptoethyl-3,5-dimethylpyrazole in dry acetonitrile
(5 ml).
After 6 h, stirring was stopped, and the solution was
filtered to eliminate any solid impurity. Acetonitrile was
then evaporated and the solid was recrystallised in a di-
chloromethane/diethyl ether mixture (1:1) (yellow solid).
Yield: 0.283 g (90%) – C18H28N4O4Pd2S2 (641.41): C,
33.71; H, 4.40; N, 8.73; S, 10.00. Found: C, 33.65; H,
4.2.3. [Pd(l-med)(PPh3)]2(BF4)2 [3](BF4)2
A solution of 0.108 g (0.18 mmol) of [Pd(l-med)Cl]2
and 0.0954 (0.36 mmol) of PPh3 were dissolved in a
mixture of dichloromethane (10 ml) and methanol (10
ml). Then, a solution of 0.0695 g (0.36 mmol) of AgBF4
in methanol (2 ml) was added dropwise with vigorous
stirring. The solution turned red. After 5 min, stirring
was stopped, and AgCl was filtered off through a Celite
pad. When the volume of the resultant solution had
been reduced to roughly 5 ml, the product precipitated
as a yellow solid. This solid was filtered and dried in
vacuo.
4.31; N, 8.80; S, 10.14%. Conductivity (X cm2 molꢁ1
,
ꢁ1
9.92 ꢃ 10ꢁ4 M in acetonitrile): 2 – IR (KBr, cmꢁ1): (C–
H)al 2921, m(OCO)as 1617, m(C@C), m(C@N) 1553,
d(CH3)as 1469, d(OCO)s 1370, d(CH3)s 1312, 1260 d(C–
H)oop 783. IR (polyethylene, cmꢁ1): m(Pd–O) 511, m(Pd–
N)as 459, m(Pd–S) 301. 1H NMR (400 MHz, CDCl3
solution) d ¼ 1.96 (s, 6H, CH3COO) 2.25 (s, 6H, Me),
2.37 (s, 6H, Me), 1.71 (ddd, 2H, pz-CH2–CHH,
3
3
2J ¼ 13.8 Hz, J ¼ 2.1 Hz, J ¼ 11.8 Hz), 2.63 (ddd, 2H,
2
3
3
pz-CH2–CHH, J ¼ 13.8 Hz, J ¼ 3.9 Hz, J ¼ 1.6 Hz),
4.52 (ddd, 2H, pz-CHH–CH2, 2J ¼ 15.2 Hz, 3J ¼ 2.1 Hz,
3J ¼ 3.9 Hz), 5.39 (ddd, 2H, pz-CHH–CH2, 2J ¼ 15.2
Hz, 3J ¼ 11.8 Hz, 3J ¼ 1.6 Hz), 5.85 (s, 2H, pz-CH).
13C{1H} NMR (63 MHz, CDCl3 solution) d ¼ 12:1
(Me), 13.6 (Me), 23.7 (CH3COO), 27.8 (S–CH2–CH2),
51.9 (pz-CH2–CH2), 107.3 (pz-CH), 150.6 (pz-C), 177.2
(CH3COO).
Yield: 0.173 g (78%) – C50H52B2F8N4P2Pd2S2
(1221.50): C, 49.16; H, 4.29; N, 4.59; S, 5.25. Found: C,
48.99; H, 4.35; N, 4.46; S, 5.37%. Conductivity (Xꢁ1 cm2
molꢁ1, 9.08 ꢃ 10ꢁ4 M in acetonitrile): 263 – IR (KBr,
cmꢁ1): m(C–H)ar 3053, m(C–H)al 2942-2917, m(C@C),
m(C@N) 1551, d(CH3)as 1480, d(CHar)as 1435, (CH3)s
1391, m(B–F) 1058, d(CHar)oop 692. IR (polyethylene,
cmꢁ1): m(Pd–N)as 450, m(Pd–P) 310, m(Pd–S) 288. 1H
NMR (400 MHz, CDCl3 solution) ¼ 1.62 (s, 6H, Me),
2.08 (s, 6H, Me), 2.14 (b, 2H, pz-CH2–CHH), 2.84 (b,
2H, pz-CH2–CHH), 4.46 (b, 2H, pz-CHH–CH2), 5.38
(b, 2H, pz-CHH–CH2), 5.78 (s, 2H, pz-CH), 7.49 (m,
4.2.2. [Pd(l-med)(py)]2(BF4)2 [2](BF4)2
A solution of 0.078 g (0.13 mmol) of [Pd(l-med)Cl]2
were dissolved in a mixture of dichloromethane (10 ml)

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578
30H, PPh3). 13C{1H} NMR (63 MHz, CDCl3 solution)
d ¼ 11:2 (Me), 13.5 (Me), 32.4 (S–CH2–CH2), 53.6 (pz-
CH2–CH2), 109.9 (pz-CH), 128.3 (m, PPh3), 133.9 (m,
PPh3), 145.1 (pz-C), 152.7 (pz-C). 31P{1H} NMR (101
MHz, CDCl3 solution) d ¼ 21:9 (s, PPh3).
was evaporated in vacuo. At this point we obtained a
mixture (1:1) of [5a](BF4) and [5b]2(BF4)2. When the
product was recrystallised in a mixture of dichlorome-
thane and methanol (1:1) at 243 K, [5b]2(BF4)2 was
obtained as a pure solid.
[5a](BF4): 1H NMR (400 MHz, CD2Cl2 solution)
d ¼ 1:92 (s, 3H, Me), 1.95 (b, 2H, CH2–CH2–CH2
dppp), 2.58 (s, 3H, Me), 2.42 (b, 1H, pz-CH2–CHH),
2.84 (b, 1H, pz-CH2–CHH), 3.09 (b, 4H, CH2–CH2–
CH2 dppp), 4.33 (b, 1H, pz-CHH–CH2), 4.76 (b, 1H, pz-
CHH–CH2), 5.70 (s, 1H, pz-CH), 7.42–7.60 (m, 20H,
PPh3). 13C{1H} NMR (63 MHz, CD2Cl2 solution)
d ¼ 12:1 (Me), 14.9 (Me), 18.5 (CH2-CH2–CH2 dppp),
24.3 (b, pz-CH2–CH2), 30.8 (b, CH2–CH2–CH2 dppp),
48.6 (b, pz-CH2–CH2), 108.2 (pz-CH), 129.4–134.2
(PPh2 dppp), 139.0, 147.5 (pz-C). 31P{1H} NMR (101
4.2.4. [Pd(l-med)(bpy)](BF4) [4a](BF4) and [Pd(l-
med)(bpy)]2(BF4)2 [4b](BF4)2
A solution of 0.034 g (0.22 mmol) of 2,20-bipyridine
in dichloromethane (5 ml) was added to a solution of
0.067 g (0.11 mmol) of [PdCl(l-med)]2 in a mixture of
dichloromethane (10 ml) and methanol (10 ml) and
immediately after a solution of 0.043 g (0.22 mmol) of
AgBF4 in methanol (2 ml) was also added. After 5 min,
stirring was stopped, and AgCl was filtered off through a
Celite pad. Solution turned dark orange. When the
volume of the resultant solution had been reduced to
roughly 5 ml, the product precipitated as an orange solid
when it had been filtered and dried in vacuo. As we
could not confirm that it was a mixture of [4a](BF4)
and [4b](BF4)2, the product was recrystallised in a
mixture (1:1) of dichloromethane and methanol, and
dark orange monocrystals of [4b](BF4)2 ꢀ 0.5CH3OH
were obtained. [4a](BF4) was again obtained when the
crystals of [4b](BF4)2 are redissolved in chloroform or
dichloromethane.
2
MHz, CD2Cl2 solution) d ¼ 0:2 (d,dppp, J ¼ 51.5 Hz),
2
13.5 (d, dppp, J ¼ 51.5 Hz). MS(ESI): m/z (%) ¼ 673
(100) [Mþ].
[5b]2(BF4)2: Yield: 0.11 g (83%) – C68H74B2F8N4P4
Pd2S2 (1521.81): C, 53.67; H, 4.90; N, 3.68; S, 4.21.
Found: C, 53.33; H, 4.58; N, 3.43; S, 4.04%. IR (KBr,
cmꢁ1): m(C–H)ar 3051, m(C–H)al 2919, m(C@C), m(C@N)
1555, d(CH3)as 1483, d(CHar)as 1436, d(CH3)s 1386, m(B–
F) 1059, d(CHal)oop 745, d(CHar)oop 693. IR (polyeth-
1
ylene, cmꢁ1): m(Pd–P) 302, m(Pd–S) 280. H NMR (400
[4a](BF4): 1H NMR (400 MHz, CDCl3 solution)
d ¼ 2:45 (s, 3H, Me), 2.48 (s, 3H, Me), 2.55 (b, 1H, pz-
CH2–CHH), 2.85 (b, 1H, pz-CH2–CHH), 4.62 (b, 1H,
pz-CHH–CH2), 4.77 (b, 1H, pz-CHH–CH2), 6.21 (s,
1H, pz-CH), 7.66 (m, 2H, bpy), 7.99 (m, 1H, bpy), 8.31
(m, 2H, bpy), 8.62 (m, 2H, bpy), 8.98 (m, 1H, bpy).
13C{1H} NMR (63 MHz, CDCl3 solution) d ¼ 12:4
(Me), 15.5 (Me), 28.4 (S–CH2–CH2), 53.4 (pz-CH2–
CH2), 109.3 (pz-CH), 124.8 (bpy), 128.1 (bpy), 141.1
(pz-C), 141.9 (bpy), 150.0(bpy), 150.5 (pz-C). MS(ESI):
m/z (%) ¼ 417 (100) [Mþ].
MHz, CD2Cl2 solution) d ¼ 1:91 (s, 6H, Me), 1.95 (b,
4H, CH2–CH2–CH2 dppp), 2.15 (s, 6H, Me), 2.62, 2.70
(m, 8H, pz-CH2C–H2), 3.09 (b, 8H, CH2–CH2–CH2
dppp), 5.65 (s, 2H, pz-CH), 7.42–7.60 (m, 40H, PPh2).
13C{1H} NMR (63 MHz, CD2Cl2 solution) d ¼ 11:3
(Me), 13.6 (Me), 18.5 (CH2–CH2–CH2 dppp), 24.3 (b,
pz-CH2–CH2), 30.8 (b, CH2–CH2–CH2 dppp), 48.6 (b,
pz-CH2–CH2), 104.9 (pz-CH), 129.4–134.2 (PPh2 dppp),
139.0, 147.5 (pz-C). 31P{1H} NMR (101 MHz, CD2Cl2
solution) d ¼ 10:2 (s,dppp).
[4b](BF4)2:C34H38B2 F8N8Pd2S2 ꢀ 0.5CH3OH (1025.28):
C, 40.41; H, 3.93; N, 10.93; S, 6.25. Found: C, 40.43; H,
3.85; N, 10.69; S, 5.98%. IR (KBr, cmꢁ1): m(C–H)ar
3081, m(C–H)al 2919, m(C@C)bpy, m(C@N)bpy 1601,
m(C@C)pz, m(C@N)pz 1551, (CH3)as 1497, d(CH3)s 1390,
m(B–F) 1059, d(C–H)oop 769. IR (polyethylene, cmꢁ1):
4.2.6. [Pd3Cl2(l-med)2(bpy)2](BF4)2 [6](BF4)2
A
solution of 0.0096
g
(0.037 mmol) of
[PdCl2(CH3CN)2] in dichloromethane (2 ml) was added
to a solution of 0.037 g (0.037 mmol) of [4b](BF4)2 in
dichloromethane (8 ml). The orange solution turned
yellow and when the volume of the resulting solution
had been reduced to roughly 5 ml the product precipi-
tated as yellow solid. This solid was filtered and dried in
vacuo.
m(Pd–Nbpy as 458, 453, m(Pd–S) 280.
)
4.2.5. [Pd(l-med)(dppp)](BF4) [5a](BF4)2 and
[Pd(l-med)(dppp)]2(BF4)2 [5b](BF4)2
Yield: 0.034 g (79%) – C34H38B2Cl2F8N8Pd3S2
(1186.62): C, 34.41; H, 3.23; N, 9.44; S, 5.40. Found: C,
34.61; H, 3.10; N, 9.24; S, 5.22%. Conductivity (Xꢁ1 cm2
molꢁ1, 1.03 ꢃ10ꢁ3 M in acetonitrile): 266 – IR (KBr,
A solution of 0.034 g (0.175 mmol) of AgBF4 in
methanol (2 ml) was added dropwise under vigorous
stirring to a solution of 0.052 g (0.088 mmol) of [PdCl(l-
med)]2 in dichloromethane (10 ml) and acetonitrile (5
ml). After 5 min, stirring was stopped, and AgCl was
filtered off through a Celite pad. A solution of 0.072 g
(0.175 mmol) of 1,3-bis(diphenylphosphino)propane
(dppp) in dichloromethane (2 ml) was then added. The
solution turned bright yellow and after 6 h the solvent
cmꢁ1): m(C–H)ar 3105–3023, m(C–H)al 2920, m(C@C)bpy
,
m(C@N)bpy 1600, (C@C)pz, m(C@N)pz 1550, d(CH3)as
1470, d(CH3)s 1391, m(B–F) 1062, (C–H)oop 766. IR
(polyethylene, cmꢁ1): m(Pd–N)as(bpy, pz) 417, m(Pd – Cl)
1
348, m(Pd–S) 279. H NMR (400 MHz, CD2Cl2 solu-
tion) d ¼ 1:88 (s, 6H, Me), 2.42 (s, 6H, Me), 2.49 (b, 2H,

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579
pz-CH2–CHH), 3.62 (b, 2H, pz-CH2–CHH), 4.79 (b,
2H, pz-CHH–CH2), 5.44 (b, 2H, pz-CHH–CH2), 6.06
(s, 2H, pz-CH), 7.45 (m, 4H, bpy), 7.95 (m, 4H, py), 8.21
(m, 4H, bpy), 8.69 (m, 2H, bpy), 9.34 (m, 2H, bpy).
13C{1H} NMR (63 MHz, CD2Cl2 solution) d ¼ 11:9
(Me), 13.5 (Me), 36.4 (S–CH2–CH2), 51.3 (pz-CH2–
CH2), 108.9 (pz-CH), 124.6 (bpy), 128.5 (bpy), 142.6
(bpy), 144.9 (pz-C), 149.4 (bpy), 151.3 (pz-C). MS(ESI):
m/z (%) ¼ 1099 (5) [M ꢀ BF4þ].
CH2–CH2–CH2 dppp), 7.49–7.81 (m, 40H, PPh2).
13C{1H} NMR (63 MHz, CD2Cl2 solution) d ¼ 18:9
(CH2–CH2–CH2 dppp), 26.2 (b, CH2–CH2–CH2 dppp),
128.9–134.1 (PPh2 dppp). 31P{1H} NMR (101 MHz,
CD2Cl2 solution) d ¼ 12:6 (s, dppp). MS(ESI): m/z (%)
¼ 1145 (5) [MꢀClþ].
[8]2þ: 1H NMR (400 MHz, CD2Cl2 solution) d ¼ 1:89
(s, 6H, Me), 2.06 (b, 4H, CH2–CH2–CH2 dppp), 2.31 (s,
6H, Me), 2.40, 3.79 (b, pz-CH2–CHH), 2.95 (b, 4H,
CH2–CH2–CH2 dppp), 4.80, 5.72 (b, pz-CHH–CH2),
5.94 (s, 2H, pz-CH), 7.44–7.84 (b, 20H, PPh2). 13C{1H}
NMR (63 MHz, CD2Cl2 solution) d ¼ 12:0 (Me), 13.7
(Me), 18.6 (CH2–CH2–CH2 dppp), 23.5 (b, CH2–CH2–
CH2 dppp), 27.7 (b, pz-CH2–CH2), 52.0 (b, pz-CH2–
CH2), 108.0 (pz-CH), 129.1–134.1 (PPh2 dppp), 143.5,
150.6 (pz-C). 31P{1H} NMR (101 MHz, CD2Cl2 solu-
tion) d ¼ 7:5 (s, dppp). MS(ESI): m/z (%) ¼ 468 (26)
[M2þ]; 961 (9) [MꢀClþ].
4.2.7. [Pd(l-Cl)(dppp)]2(BF4)2 [7](BF4)2 and [Pd2
(l-med)2(dppp)]2þ [8]2þ
A
solution of 0.0041
g
(0.016 mmol) of
[PdCl2(CH3CN)2] in dichloromethane (2 ml) was added
to a solution of 0.024 g (0.016 mmol) of [5b](BF4)2 in
dichloromethane (8 ml).The solution was stirred for 4 h
2þ
and a mixture of [Pd(l-Cl)(dppp)]2 [7]2þ and [Pd2(l-
med)2(dppp)]2þ [8]2þ was formed. When the mixture
was recrystallised with dichloromethane/diethyl ether
(1:1), [Pd(l-Cl)(dppp)]2(BF4)2 [7](BF4)2 was obtained as
4.3. X-ray crystallographic study
a pure solid. [8]2þ was always obtained in the presence of
2þ
[Pd(l-Cl)(dppp)]2
.
Suitable crystals for X-ray diffraction experiments
of compounds [3](BF4)2 ꢀ 2CH3CN and [4b](BF4)2 ꢀ
0.5CH3OH were obtained by crystallisation from ace-
tonitrile and methanol, respectively. Data were collected
on a MAR345 diffractometer with Image Plate detector,
using u-scan technique. Both crystals were collected
with graphite-monochromated Mo Ka radiation. The
structures were solved by direct methods using the
[7](BF4)2: Yield: 0.006 g (59%) –C54H52B2Cl2F8P4Pd2
(1282.24): C 50.58, H 4.09. Found: C 50.86, H 4.26%. IR
(KBr, cmꢁ1): m(C–H)ar 3055, (C–H)al 2919, d(CH3)as
1484, d(CHar)as 1435, m(B–F) 1067, d(CHal)oop 743,
d(CHar)oop 692. IR (polyethylene, cmꢁ1): m(Pd–P) 289,
1
m(Pd–Cl)B 313. H NMR (400 MHz, CD2Cl2 solution)
d ¼ 2:06 (b, 4H, CH2–CH2–CH2 dppp), 2.45 (b, 8H,
Table 2
Crystallographic data for the two crystal structures
Compound
[3](BF4)2 ꢀ 2CH3CN
54H58B2F8N6P2Pd2S2
[4b](BF4)2 ꢀ 0.5CH3OH
C34:5H40B2F8N8O0:5Pd2S2
Empirical formula
Molecular mass (g)
Temperature (K)
Crystal system
C
1303.54
293
triclinic
1025.28
293
triclinic
ꢃ
ꢃ
Space group
Unit cell dimensions
P1
P1
ꢂ
a (A)
10.7500(10)
10.8610(10)
13.0670(10)
104.45
11.8760(10)
12.9140(10)
15.5750(10)
104.32
ꢂ
b (A)
ꢂ
c (A)
a (°)
b (°)
c (°)
100.75
100.15
100.07
110.95
2068.0(3)
3
ꢂ
Volume (A )
1411.1(2)
1
1.534
Z
2
1.647
Dcalc: (g cmꢁ3
)
l (mmꢁ1
F(000)
)
8.36
636
10.45
1026
Crystal size (mm)
h Range (°)
0:2 ꢃ 0:1 ꢃ 0:2
1.99–28.84
6223, 4954, 0.0212
4954/20/385
0.0496, 3.3649
0.0439, 0.1053
0.0555, 0.1113
0.661, )0.867
2
0:1 ꢃ 0:1 ꢃ 0:3
2.63–28.90
12131, 7442, 0.0224
7442/20/489
0.0878, 0.8021
0.0430, 0.1301
0.0595, 0.1411
0.826, )0.786
Reflexions collected:total, independent, Rint
Data/restraints/parameters
a=bꢄ
Final R1, wR2
R1 (all data), wR2
Residual electron density (e A
ꢁ3
ꢂ
)
P
2
2
2
2
2
The function minimised was
wðjFoj ꢁ jFcj Þ , where w ¼ ½r2ðIÞ þ ðaPÞ þ bPꢅꢁ1, and P ¼ ðjFoj þ 2jFcj Þ=3.

ꢀ
ꢀ
J. Garcıa-Anton et al. / Inorganica Chimica Acta 357 (2004) 571–580
580
SHELXS 97-computer program and refined by full-
matrix least-squares method with a SHELXS 97-com-
puter program [23].
[6] (a) A. Boixassa, J. Pons, A. Virgili, X. Solans, M. Font-Bardia, J.
Ros, Inorg. Chim. Acta 340 (2002) 49;
(b) A. Boixassa, J. Pons, X. Solans, M. Font-Bardia, J. Ros,
Inorg. Chim. Acta 346 (2003) 151;
All hydrogen atoms were computed and refined using
a riding model. The final R (on F) factor and xR (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 2.
(c) A. Boixassa, J. Pons, X. Solans, M. Font-Bardia, J. Ros,
Inorg. Chim. Acta (in press);
(d) A. Boixassa, J. Pons, J. Ros, R. Mathieu, N. Lugan, J.
Organomet. Chem. (in press);
(e) A. Boixassa, J. Pons, J. Ros, X. Solans, M. Font-Bardia,
Inorg. Chim. Acta. (accepted).
ꢀ
[7] (a) J. Garcia-Anton, J. Pons, X. Solans, M. Font-Bardia, J. Ros,
ꢀ
Eur. J. Inorg. Chem. (2002) 3319;
ꢀ
ꢀ
(b) J. Garcia-Anton, J. Pons, X. Solans, M. Font-Bardia, J. Ros,
Eur. J. Inorg. Chem. (2003) 2992–3000;
5. Supplementary material
ꢀ
(c) J. Garcia-Anton, J. Pons, X. Solans, M. Font-Bardia, J. Ros,
ꢀ
Eur. J. Inorg. Chem. (in press).
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been de-
posited with the Cambridge Crystallographic Data
Centre as supplementary publication No. CCDC 212888
([3](BF4)2 ꢀ 2CH3CN) and CCDC 212889 ([4b](BF4)2 ꢀ
0.5CH3OH). 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, Cambridge CB2 1EZ, UK; fax: (internat.) +44-
1223/336-033; email: deposit@ccdc.cam.ac.uk].
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Inorg. Chim. Acta (in press).
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Acknowledgements
Support by the Spanish Ministerio de Educaciꢀon y
Cultura (Project BQU2000-0238 and a grant to J.G.) is
gratefully acknowledged.
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