Synthesis and Characterization of New Palladium(II) Complexes Containing N-Alkylamino-3,5-diphenylpyrazole Ligands. Crystal Structure of [PdCl(L2)](BF4) {L2 ≤ Bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl] ethylamine}

Article abstract of DOI:10.1071/CH08521

In this paper, the synthesis of two new N,N′,N-ligands, bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]amine (L1) and bis[2-(3,5-diphenyl-1- pyrazolyl)ethyl]ethylamine (L2) is reported. These ligands form complexes with the formula [PdCl(N,N′,N)]Cl when reacting w

Full text of DOI:10.1071/CH08521

Full Paper
CSIRO PUBLISHING
www.publish.csiro.au/journals/ajc
Aust. J. Chem. 2009, 62, 475–482
Synthesis and Characterization of New Palladium(II)
Complexes Containing N-Alkylamino-3,5-diphenylpyrazole
Ligands. Crystal Structure of [PdCl(L2)](BF4) {L2 =
Bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]ethylamine}
Gemma Aragay,A Josefina Pons,A,D Jordi García-Antón,A Ángeles Mendoza,A,B
Guillermo Mendoza-Díaz,B Teresa Calvet,C Mercè Font-Bardia,C
and Josep RosA
ADepartament de Química, Unitat de Química Inorgànica, Universitat Autònoma de Barcelona,
08193 Bellaterra, Barcelona, Spain.
BFacultad de Química, Universidad de Guanajuato, 36050 Guanajuato, Mexico.
CCristal.lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona,
Martí i Franquès s/n, 08028 Barcelona, Spain.
DCorresponding author. Email: Josefina.Pons@uab.es
In this paper, the synthesis of two new N,Nꢀ,N-ligands, bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]amine (L1) and bis[2-(3,5-
diphenyl-1-pyrazolyl)ethyl]ethylamine (L2) is reported.These ligands form complexes with the formula [PdCl(N,Nꢀ,N)]Cl
when reacting with [PdCl2(CH3CN)2] in a 1:1 metal-to-ligand molar ratio. Treatment of these ligands with
[PdCl2(CH3CN)2] in a 1:1 metal-to-ligand molar ratio in the presence ofAgBF4 or NaBF4 gave [PdCl(N,Nꢀ,N)](BF4) com-
plexes. These PdII complexes were characterized by elemental analyses, conductivity measurements, mass spectrometry,
and IR, 1H, and 13C{1H} NMR spectroscopies. The X-ray structure of the complex [PdCl(L2)](BF4) has been determined.
The metal atom is coordinated by two azine nitrogen atoms and one amine nitrogen atom of the aminopyrazole ligand. The
distorted square planar coordination is completed by one chlorine atom. In this complex, intermolecular π–π stacking
interactions are present.
Manuscript received: 27 November 2008.
Final version: 20 January 2009.
Introduction
uninegative PPB and neutral PPA. In particular, we have pre-
sented the reactivity of the bis[2-(3,5-dimethyl-1-pyrazolyl)
Trofimenko initiated the studies of poly(1-pyrazolyl)borates
(PPB) as histidine donor models and reported the synthesis
of a wide variety of chelates of various elements that pro-
vide a fascinating and fertile field of research to inorganic
chemists, mainlythedesignofchelatingsystemstomimic, study,
and understand natures’ systems.[1–5] Poly(1-pyrazolyl)alkanes
(PPA) are neutral ligands that are isoelectronic and isosteric with
the uninegative poly(1-pyrazolyl)borates. For this reason, these
ligands are also appropriate mimics of the naturally occurring
histidine residues found in metalloenzymes.[6]
Although the synthesis of metalloenzyme models relevant
to biochemistry is an important field of application of these
compounds, in recent years, some other fields have been of
wide interest, including the coinage metal chemistry or the
development of homogeneous catalysts.[7–9] A proof of the
importance of these new fields of research is the review reported
by Dias and Lovely in 2008 about useful stabilities of a range
of complexes including coinage metal adducts that contain car-
bonyl and olefin groups supported by poly(pyrazolyl)alkane and
poly(pyrazolyl)borate ligands.[10]
ethyl]amine
ligand
with
[RhCl(cod)]2
(cod = 1,5-
cyclooctadiene).[15] Moreover, with a similar ligand, bis[2-(3,5-
dimethyl-1-pyrazolyl)ethyl]ethylamine, we have described its
reactivity with RhI,[16] PdII,[13] PtII,[12] and ZnII.[11]
In addition, we have recently reported the synthesis and
characterization of two 3,5-diphenyl-N-dialkylaminopyrazole
ligands and studied their reactivity with PdII, which yields
three different complexes for each ligand: N,Nꢀ-chelated, N-
zwitterionic, and C,N,Nꢀ-cyclopalladated compounds.[19]
The aim of this paper is to extend this work to a new family
of N,Nꢀ,N ligands, bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]amine
(L1)andbis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]ethylamine(L2),
and study their reactivity with PdII. We have isolated complexes
[PdCl(N,Nꢀ,N)]Cl (N,Nꢀ,N = L1 (1) and L2 (2)) and complexes
[PdCl(N,Nꢀ,N)](BF4) (N,Nꢀ,N = L1 (3) and L2 (4)). The lig-
ands contain two pyrazole nitrogens and one amine nitrogen as
potential N-donor atoms (Fig. 1).
Results and Discussion
Synthesis and Characterization of the Ligands
In previous papers, we have reported the study of a family
of tris(pyrazolyl)amine and bis(pyrazolyl)amine ligands,[11–18]
which present a similar configuration to those found for
Synthesis of the ligand bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]
amine (L1) consists of the treatment of 3,5-diphenylpyrazole
© CSIRO 2009
10.1071/CH08521
0004-9425/09/050475

476
G. Aragay et al.
values).[24,25] These compounds do not show a different elec-
trolyte nature depending on the solvent used as has been reported
for their analogues with methyl groups in positions 3 and 5 of the
pyrazolyl group.[13] The conductivity values of complexes 3 and
4 in acetonitrile are also in agreement with a 1:1 electrolyte.[24,25]
The IR spectra of all compounds are similar to those of the
ligands. The most characteristic bands are those attributable to
the phenyl and pyrazolyl groups: ν(C=C) and ν(C=N) between
R
N
N
N
N
N
1554 and 1549 cm−1 and δ(C–H)oop between 763 and 695 cm−1
.
R ϭ H (L1)
R ϭ Et (L2)
The ν(B–F) band between 1084 and 1062 cm−1 is character-
istic for compounds 3 and 4.[21,22] IR spectra of complexes 1
and 3 show moderated shifts of the ν(N–H) bands, 3140 and
3122 cm−1, respectively, in comparison to the free ligands. The
IR spectra for all complexes in the 600–100 cm−1 range were
also studied. Complexes 1–4 show−o1ne band that corresponds to
ν(Pd–N) between 521 and 487 cm , and one band attributable
Fig. 1. Pyrazole derived ligands.
with bis(2-chloroethyl)amine in the presence of sodium hydride
in N,N-dimethylformamide (DMF). The ligand is further puri-
fied by chromatography (silica gel 60 Å) with ethyl acetate as
eluent.
Synthesisoftheligandbis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]
ethylamine (L2) consists of the treatment of 1-(2-toluene-
p-sulfonyloxyethyl)-3,5-diphenylpyrazole[20] with ethylamine
in the presence of sodium hydroxide in tetrahydrofuran
(THF)/water (60/40).
Both ligands are obtained as yellow oils. The ligands were
characterized by elemental analyses, IR, 1H, and 13C{1H}
NMR spectroscopies, and mass spectrometry. The NMR sig-
nals were assigned by reference to the literature[21,22] and from
distortionless enhancement by polarization transfer (DEPT),
correlation spectroscopy (COSY), and heteronuclear multiple
quantum coherence (HMQC) NMR experiments.
to ν(Pd–Cl) between 348 and 340 cm−1 [26]
.
The 1H, 13C{1H}, DEPT, COSY, HMQC, and nuclear Over-
hauser effect correlation spectroscopy (NOESY) NMR spectra
were recorded in CDCl3 for 1 (Fig. 2) and 2, and in CD3CN
for 3 and 4 (see Figs S2–S4 in the Accessory Publication for
complexes 2–4, respectively).
For complexes 1 and 2 in CDCl3 and 4 in CD3CN, the
two protons of each CH2 group of each NpzCH2CH2Namino
chain are diastereotopic, thus give rise to four groups of sig-
nals, each one attributable to a single hydrogen atom of each
NpzCH2CH2Namino chain. HMQC spectra were used to assign
the signals of protons H-16 and H-17. Each group of signals in
both complexes can be assigned as two doublets of doublets of
doublets for H-16 in complexes 1, 2, and 4 and H-17 in com-
plexes 2 and 4 (for complex 4, the two doublets of doublets of
doublets attributable to protons H-17 appear overlapped). For
H-17 in complex 1, two doublets of doublets of doublets of dou-
blets are obtained, as a result of the additional coupling of this
Synthesis and Spectroscopic Properties of the Complexes
Complexes [PdCl(N,Nꢀ,N)]Cl (N,Nꢀ,N = L1 (1) and L2 (2))
were obtained by treatment of the corresponding ligand with
[PdCl2(CH3CN)2][23] in a 1:1 metal-to-ligand molar ratio
in acetonitrile (1) or dichloromethane (2). The reaction of
[PdCl2(CH3CN)2] with the corresponding ligand (L1 or L2), in
a 1:1 metal-to-ligand molar ratio in dichloromethane/methanol
(1/1) (3) or acetonitrile (4), in the presence of AgBF4 (3) or
NaBF4 (4), yields compounds of formula [PdCl(N,Nꢀ,N)](BF4)
(N,Nꢀ,N = L1 (3) and L2 (4)).
proton with Hamino
.
The 1H NMR spectrum of complex 3 in CD3CN, at
room temperature, displays broad bands for the protons of
the NpzCH2CH2Namino chains, which implies that a dynamic
process is taking place in solution at room temperature.
This prompted us to record variable-temperature spectra
(Fig. 3). We have observed that the bands that correspond to
NpzCH2CH2Namino chains become well-defined bands when we
increase the temperature to 338 K. Each group of signals can be
assigned as two doublets of doublets of doublets for H-16 and
two doublets of doublets of doublets of doublets for H-17, as a
Several techniques were used for the characterization of all
complexes: elemental analyses, conductivity measurements, IR,
1H, and 13C{1H} NMR spectroscopies, mass spectrometry, and
X-ray diffraction methods.
result of the additional coupling of this proton with Hamino
.
The elemental analyses of products 1 and 2 were consis-
tent with the formula [PdCl2(N,Nꢀ,N)] (N,Nꢀ,N = L1 and L2)
and those for compounds 3 and 4 with [PdCl(N,Nꢀ,N)](BF4)
(N,Nꢀ,N = L1 and L2).
Up to now, from our previous research, the dynamic pro-
cesses that take place in solution were attributed to fluxional
equilibria in which, with ring-flipping, the two hydrogens of
each CH2 of a Npz–CH2CH2–X (X = Namino, S) chain were
interconverted and only one signal could be observed. At low
temperatures, these processes did not have enough energy to
take place.[11,27,28] However, as aforementioned, in this case we
observe better resolution of the signals at higher temperatures.
This could be explained by a dynamic process that implies the
formation of aggregates that contain the cationic units by means
of hydrogens bonds.These hydrogen bonds can be detected in the
1H NMR spectra at variable temperature of complex 3: the chem-
ical shift of the signal that corresponds to the amino group varies
with temperature, which shifts to lower fields with decreasing
temperature (from 5.70 ppm at 338 K to 5.78 ppm at 298 K) as
expected for this kind of process.[29,30]
Molecular weights of 1–4 were confirmed by mass spec-
trometry studies. The positive ionization mass spectra (ESI+)
gave peaks with m/z values of 614.1 (100%) for 1, attributable
to [PdCl2(L1)–HCl–Cl]+, 678.1 (100%) for 2, attributable to
[PdCl(L2)]+, and 614.1 (100%) and 678.1 (100%), for com-
pounds 3 and 4, respectively, attributable to [PdCl(L1) − HCl]+
(3) and [PdCl(L2)]+ (4). Molecular peaks of the cations are
observed with the same isotope distribution as the theoretical
ones (see Fig. S1, Accessory Publication).
Molar conductances of complexes 1 and 2 measured in
acetonitrile and methanol, are in agreement with a 1:1 elec-
trolyteformulationofbothcompounds(comparedwithtabulated

New Palladium(ii) Complexes
477
ϩ
H-17b
H-17a
H-16a
H-16b
H
N
N
N
N
N
N
amino
H-17a
Pd
Cl
N
pz
Experimental
4.800 4.700 4.600 4.500 4.400 4.300 4.200 4.100 4.000 3.900 3.800 3.700 3.600 3.500 3.400 3.300 3.200 3.100 3.000 2.900
H-17b
H-17a
H-16b
H-16a
Simulated
Fig. 2. The experimental (250 MHz, CDCl3, 298 K) and simulated (g NMR) 1H NMR spectra for H-16 and H-17 protons of the NpzCH2CH2Namino fragment
of [PdCl(L1)]Cl (1).
Treatment of the signals of the NpzCH2CH2Namino chains
from the 1H NMR spectra at 298 K for 1, 2, and 4 and at 338 K
for 3 as AAꢀXXꢀ systems gave a set of coupling constants for
each complex. These constants are consistent with the simu-
lated spectra for compounds 1–4, obtained with the aid of the
g NMR program.[31] All the results are reported in the Experi-
mental section. Fig. 2 shows the experimentally determined and
simulated spectra for compound 1. The rest of the figures with
the experimentally and simulated spectra for compounds 2–4
are compiled in the Accessory Publication, Figs S2–S4. Sim-
ulation of the terminal chain (NaminoCH2CH3) for complex 2
was also necessary because of overlap of the signal attributable
to protons H-17b with the signal attributable to protons
NaminoCH2CH3.
In the NOESY spectra of complexes 1 and 2 in CDCl3, and
complexes 3 and 4 in CD3CN, the phenyl protons linked to the
pyrazole at δ 7.42–7.19 (1), 7.70–7.23 (2), 7.65–7.48 (3), and
7.61–7.45 (4), show NOE interaction with the doublets of dou-
blets of doublets at δ 4.63 (1), 5.66 (2), 5.28 (3), and 5.56 (4), but
not with the ones at δ 4.50 (1), 5.10 (2), 4.83 (3), and 4.69 (4).
We assign H-16b to the doublets of doublets of doublets at δ 4.63
(1), 5.66 (2), 5.28 (3), and 5.56 (4) and H-16a to the doublets
of doublets of doublets at δ 4.50 (1), 5.10 (2), 4.83 (3), and
4.69 (4).
These assignments were possible thanks to the X-ray crystal
structure of 4, which shows that the shortest distance is between
the phenyl protons linked to the pyrazole at δ 7.61–7.45 and the
doublet of doublets of doublets at δ 5.56 (H21· · · H22 = 2.355 Å,
Fig. 4).
For compounds 1–4, coupling constants (obtained from the
1
g NMR generated H NMR simulated spectra,[31] Fig. 2 and
Accessory Publication Figs S2–S4) helped us to differentiate
H-17a from H-17b. These coupling constants are in agreement
with the conformation of the Npz–CH2–CH2–Namino chains,
which have been corroborated by the X-ray crystal study of
complex 4.
2
Geminal J and ≈180◦ 3J coupling constants have signifi-
cantly higher values than ≈30◦ and ≈60◦ 3J coupling constants
(Fig. 2).[21] Thus, protons H-17a should correspond to the dou-
blets of doublets of doublets at δ 3.13 (1), 3.15 (2), 3.02 (3), and

478
G. Aragay et al.
H-16a
H-16b
H-17b
H-17a
NH
338 K
328 K
318 K
308 K
298 K
6.2
6.0
5.8
5.6
5.4
5.2
5.0
4.8
4.6
ppm
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
Fig. 3. 1H NMR spectra (250 MHz) of complex 3 in CD3CN at variable temperature (298–338 K).
C34
Crystal Structure of [PdCl(L2)](BF4) (4)
C33
C3
The crystal structure of compound 4 consists of discrete
[PdCl(L2)]+ units and BF−4 anions (Fig. 4). The cation com-
plex is mononuclear, with the PdII centre coordinated to the
L2 ligand by its three donor atoms (two nitrogen atoms of the
pyrazolyl groups and one nitrogen atom of the amine moiety),
along with one chlorine atom in a slightly distorted square-
planar geometry.The tetrahedral distortion can be observed from
the bond angles and from the mean separation (0.073 Å) of
the atoms coordinated to the Pd atom in relation to the mean
plane that contains these four atoms and the Pd atom. The dihe-
dral angle between the planes N5–Pd–N3 and N1–Pd–N3 is
2.92◦. The L2 ligand acts as a tridentate chelate and forms two
six-membered rings, with a boat conformation for Pd–N1–N2–
C16–C17–N3 and for Pd–N5–N4–C21–C20–N3, which share
an edge (Pd–N3(amino)).
C4
C5
C35
C36
C2
C1
C32
C31
C6
C7
CI
C30
N5
C29
C28
Pd
C8
C9
N1
N4
C19
C18
C26
N3
C17
C15
C27
N2
C21
C25
C10
C11
C14
C16
C20
C22
C23
C24
C12 C13
The PdN3Cl core is present in 116 complexes in the
literature.[32] The Pd–Npz [2.040(2) Å and 2.015(2) Å], the Pd–
Namino [2.099(2) Å], and the Pd–Cl bond lengths [2.288(1) Å]
can be regarded as normal compared with the distances found
in the literature. For Pd–Npz, the literature describes val-
ues between 1.979 and 2.141 Å,[19,27–29,33–39] for Pd–Namino
between 2.017 and 2.280 Å,[13,14,19,40–46] and for Pd–Cl between
2.280 and 2.341 Å.[13,14,19,27–29,33–40] In particular, all the values
are similar to those found for the complex [PdCl(ddae)]Cl·H2O
(ddae = bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]ethylamine).[13]
The Npz–Pd–Namino bite angles are 87.81(8)◦ and 91.81(8)◦,
and are similar to the corresponding bite angles in the
[PdCl(ddae)]Cl·H2O complex.[13]
Fig. 4. ORTEP drawing of [PdCl(L2)]+ cation of complex 4, showing
all non-hydrogen atoms and the atom-numbering scheme; 50% probability
amplitude displacement ellipsoids are shown. Selected bond parameters:
Pd–N(1) 2.040(2), Pd–N(3) 2.099(2), Pd–N(5) 2.015(2), Pd–Cl 2.288(1) Å;
N(5)–Pd–N(1) 177.06(8), N(5)–Pd–N(3) 91.81(8), N(1)–Pd–N(3) 87.81(8),
N(1)–Pd–Cl 90.49(6), N(5)–Pd–Cl 89.64(6), N(3)–Pd–Cl 174.52(6)◦.
3.16 (4) and H-17b to the ones at δ 3.44 (1), 4.66 (2), 3.25 (3),
and 3.23 (4) (comparative Tables S1 and S2 can be found in the
Accessory Publication).
All these data would indicate that for compounds 1–4, the N-
alkylamino-3,5-diphenylpyrazole ligands present a κ3(N,Nꢀ,N)
coordination mode.

New Palladium(ii) Complexes
479
Complex 4 shows π–π stacking interactions (Fig. S5 can
be found in the Accessory Publication). The angle between the
planes formed by the two phenyl rings C22–C23–C24–C25–
C26–C27 of two different ligands in two different molecules is
0◦, which confirms a perfect face-to-face interaction. However,
only C25 and C26 atoms build a parallel displaced π–π stacking
interaction. The distance between the pair of carbons is 3.737 Å,
in agreement with the interval found in the bibliography for this
kind of interaction [3.3–3.8 Å].[47]
of 60%, 13 mmol) in 10 mL of the same solvent at room tem-
perature. After hydrogen evolution had ceased, the mixture was
warmed to 60◦C and stirred for 2 h. Subsequently, a solution
of bis(2-chloroethyl)amine hydrochloride (0.80 g, 4.5 mmol) in
5 mL of dry DMF was added to the initial solution and the
mixture was stirred for 24 h to produce a cream white disper-
sion. After filtration of the precipitated NaCl, the solvent was
evaporated under vacuum. The resulting oil was dissolved in
50 mL of chloroform, washed with saturated aqueous sodium
chloride solution (3 × 50 mL), and dried overnight with anhy-
drous Na2SO4. The solution was filtered and the solvent was
removed under vacuum to obtain the product as a yellow oil.
The ligand was further purified by chromatography (silica gel
60 Å) with ethyl acetate as eluent.
L1: (0.75 g, 33%). (Found: C 80.02, H 5.98, N 13.58.
C34H31N5 (509.6) requires C 80.13, H 6.13, N 13.74%). νmax
(NaCl)/cm−1 ν(N–H) 3307, ν(C–H)ar 3059, ν(C–H)al 2939,
2851, δ(N–H) 1735, ν(C=C)ph 1605, [ν(C=C)pz, ν(C=N)pz]
1549, [δ(C=C)ar, δ(C=N)ar] 1483, 1462, δ(C–H)ip 1074, δ(C–
H)oop ar 760, 649. δH (250 MHz, CDCl3, 298 K) 7.82 (d, 4H,
3J 7.4, ortho-Ph), 7.38–7.26 (m, 16H, Ph), 6.56 (s, 2H, Npz–
CH), 4.23 (t, 4H, 3J 7.5, Npz–CH2–CH2–Nam), 3.06 (t, 4H, 3J
7.5, Npz–CH2–CH2–Nam), 2.03 (br, 1H, NHam). δC (63 MHz,
CDCl3, 289 K) 151.2, 145.8 (Npz–C), 133.9–126.0 (Ph), 103.8
(Npz–CH), 49.7, 49.5 (Npz–CH2–CH2–Nam). m/z (ESI+) 510.3
(100%, [L1 + H]+).
Conclusions
The reaction of N,Nꢀ,N ligands, L1 and L2, with [PdCl2(CH3
CN)2] yields compounds [PdCl(N,Nꢀ,N)]Cl (N,Nꢀ,N = L1 (1),
L2 (2)). Analytical and spectroscopic data of these complexes
lead us to predict that the ligands coordinate the PdII cen-
tre through the azine nitrogens of both pyrazolyl groups and
the amine group. If the reaction is performed in the presence
of AgBF4 (3) or NaBF4 (4), compounds [PdCl(N,Nꢀ,N)](BF4)
(N,Nꢀ,N = L1 (3), L2 (4)) are obtained. In these complexes, the
ligands are also coordinated to the metallic centre through their
three donor atoms (two Npz and one Namino). Therefore, we have
observed for all compounds a κ3(N,Nꢀ,N) coordination mode of
the N-alkylamino-3,5-diphenylpyrazole ligands.
The X-ray structure of compound 4 confirms the coordination
of L2 to the PdII centre by two azine nitrogens and one amine
nitrogen. The PdII centre completes its coordination with one
chlorine atom. In this complex, intermolecular displaced π–π
stacking interactions are present.
Synthesis of the Ligand Bis[2-(3,5-diphenyl-
1-pyrazolyl)ethyl]ethylamine (L2)
Experimental
A solution of ethylamine (0.09 g of 70%, 1.45 mmol) and
sodium hydroxide (0.15 g of 98%, 3.63 mmol) was added to
1-(2-toluene-p-sulfonyloxyethyl)-3,5-diphenylpyrazole (1.56 g,
2.90 mmol) in a mixture of THF/water (60/40). The reaction
was stirred under reflux for 8 days. Ethylamine and sodium
hydroxide were added in four different portions during the reac-
tion process (0.36 mmol of ethylamine and 0.91 mmol of sodium
hydroxide every 48 h). The mixture was then cooled to room
temperature and extracted three times with 10 mL of chloro-
form. The organic phase was collected and dried overnight with
anhydrous Na2SO4. The solution was filtered off and the sol-
vent was removed under vacuum to obtain the final product as a
yellow oil.
General Details
The reactions were carried out under nitrogen using vacuum-
line and Schlenk techniques. Solvents were dried and distilled
according to standard procedures and stored under nitrogen.
Elemental analyses (C, H, N) were carried out by the staff of
the Chemical Analyses Service of the Universitat Autònoma
de Barcelona on a Carlo Erba CHNS EA-1108 instrument.
Conductivity measurements were performed at room temper-
ature in 10−3 M acetonitrile and methanol solutions, employing
a CyberScan CON 500 (Euthech Instruments) conductimeter.
Infrared spectra were run on a Perkin–Elmer FT spectrophoto-
meter, series 2000 cm−1 as NaCl pellets, KBr pellets, or
polyethylene films in the range 4000–100 cm−1. 1H, 13C{1H},
DEPT, COSY, HMQC, and NOESY NMR spectra were recorded
with a NMR-FT Bruker 250 MHz spectrometer in CDCl3 or
CD3CN solutions at room temperature and variable temperature
when required. All chemical-shift values (δ) are given in ppm.
Mass spectra were obtained with an Esquire 3000 ion-trap mass
spectrometer from Bruker Daltonics. Mass spectrometry assign-
ments were supported by isotopic simulations. All chemicals
used were of AR grade. Bis(2-chloroethyl)amine hydrochlo-
ride (C4H9NCl2·HCl; Mw 178.49) and 3,5-diphenylpyrazole
(C15H12N2; Mw 220.27) were purchased from Sigma–Aldrich
(Steinheim, Germany). The complex [PdCl2(CH3CN)2] was
synthesized according to published methods.[23] The precur-
sor 1-(2-toluene-p-sulfonyloxyethyl)-3,5-diphenylpyrazole was
prepared as described in the literature.[20]
L2: (0.58 g, 74%). (Found: C 80.53, H 6.29, N 13.15.
C36H35N5 (537.7) requires C 80.41, H 6.56, N 13.02%).
νmax (NaCl)/cm−1 ν(C–H)ar 3060, ν(C–H)al 2928, 2861,
ν(C=C)ph 1605, [ν(C=C)pz, ν(C=N)pz] 1550, [δ(C=C)ar,
δ(C=N)ar] 1492, 1451, δ(C–H)ip 1094, δ(C–H)oop ar 763, 694.
δH (250 MHz, CDCl3, 298 K) 7.80 (d, 4H, 3J 7.3, ortho-
Ph), 7.33–7.22 (m, 16H, Ph), 6.53 (s, 2H, Npz–CH), 4.05 (t,
4H, 3J 6.3, Npz–CH2–CH2–Nam), 2.83 (t, 4H, 3J 6.3, Npz–
CH2–CH2–Nam), 2.34 (q, 2H, 3J 7.1, Nam–CH2–CH3), 0.76
3
(t, 3H, J 6.9, Nam–CH2–CH3). δC (63 MHz, CDCl3, 298 K)
151.2, 146.1 (Npz–C), 133.1–125.9 (Ph), 103.4 (Npz–CH), 68.1
(Npz–CH2–CH2–Nam), 47.7 (Npz–CH2–CH2–Nam), 43.0 (Nam
–
CH2–CH3), 21.4 (Nam–CH2–CH3). m/z (ESI+) 538.3 (100%,
[L2 + H]+).
Synthesis of the Complexes [PdCl(N,Nꢀ,N)]Cl
(N,Nꢀ,N = L1 (1), L2 (2))
Synthesis of the Ligand Bis[2-(3,5-diphenyl-
1-pyrazolyl)ethyl]amine (L1)
A solution of [PdCl2(CH3CN)2] (0.070 g, 0.27 mmol) in dry
acetonitrile (1) or dry dichloromethane (2), was added to a solu-
tion of 0.27 mmol of the corresponding ligand (L1: 0.136 g and
A solution of 3,5-diphenylpyrazole (1.96 g, 8.9 mmol) in 5 mL
of dry DMF was added to a solution of sodium hydride (0.52 g

480
G. Aragay et al.
L2: 0.150 g) in the same solvent (5 mL). The mixture was stirred
at room temperature for 12 h and a pale yellow (1) or orange
(2) solid precipitated. The solids were filtered off and washed
twice with dry and cool diethyl ether (3 mL), to yield the desired
compounds.
acetonitrile) 126.1. νmax (KBr)/cm−1 ν(N–H) 3122, ν(C–
H)ar 3048, ν(C–H)al 2926–2849, [δ(N–H), ν(C=C)ph] 1623,
[ν(C=C)pz, ν(C=N)pz] 1554, [δ(C=C)ar, δ(C=N)ar] 1483,
1469, ν(B–F) 1084, δ(C–H)ip 1034, δ(C–H)oop ar 763, 696. νmax
(polyethylene)/cm−1 ν(Pd–N) 494, ν(Pd–Cl) 345. δH (250 MHz,
CD3CN, 298 K): 8.22 (d, 4H, 3J 7.4, ortho-Ph), 7.65–7.47
(m, 16H, Ph), 6.83 (s, 2H, Npz–CH), 5.79 (br, 1H, NHam),
5.26 (br, 2H, Npz–CHH–CH2–Nam), 4.80 (br, 2H, Npz–CHH–
CH2–Nam), 3.20 (br, 2H, Npz–CH2–CHH–Nam), 3.00 (br, 2H,
Npz–CH2–CHH–Nam). δH (250 MHz, CD3CN, 338 K): 8.18
(d, 4H, 3J 7.4, ortho-Ph), 7.65–7.48 (m, 16H, Ph), 6.80 (s,
Compound 1 (0.061 g, 33%). (Found: C 59.22, H 4.31,
N 9.90. C34H31Cl2N5Pd (687.0) requires C 59.44, H 4.55,
N 10.20%). Conductivity (ꢀ−1 cm2 mol−1, 1.1 × 10−3 M in
methanol): 96.0. Conductivity (ꢀ−1 cm2 mol−1, 9.3 × 10−4 M
in acetonitrile): 133.2. νmax (KBr)/cm−1 ν(N–H) 3140,
ν(C–H)ar 3060, ν(C–H)al 2944, δ(N–H) 1620, ν(C=C)ph
1605, [ν(C=C)pz, ν(C=N)pz] 1549, [δ(C=C)ar, δ(C=N)ar]
1485, 1462, δ(C-H)ip 1029, δ(C–H)oop ar 760, 697. νmax
(polyethylene)/cm−1 ν(Pd–N) 487, ν(Pd–Cl) 340. δH (250 MHz,
2
2H, Npz–CH), 5.70 (br, 1H, NHam), 5.28 (ddd, 2H, J 15.57,
3J 2.24, 3J 8.61, Npz–CHH–CH2–Nam), 4.83 (ddd, 2H, 2J
15.57, 3J 6.54, 3J 3.00, Npz–CHH–CH2–Nam), 3.25 (dddd,
2H, 2J 13.28, 3J 2.24, 3J 6.54, 3J 8.65, Npz–CH2–CHH–
3
CDCl3, 298 K): 7.28 (d, 4H, J 7.2, ortho-Ph), 7.42–7.19 (m,
16H, Ph), 6.55 (s, 2H, Npz–CH), 5.25 (br, 1H, NHam), 4.63
(ddd, 2H, 2J 13.00, 3J 5.93, 3J 6.37, Npz–CHH–CH2–Nam),
4.50 (ddd, 2H, 2J 13.00, 3J 6.34, 3J 6.82, Npz–CHH–CH2–Nam),
3.44 (dddd, 2H, 2J 12.94, 3J 5.93, 3J 6.34, 3J 8.99, Npz–CH2–
CHH–Nam), 3.13 (dddd, 2H, 2J 12.94, 3J 6.37, 3J 6.82, 3J
4.33, Npz–CH2–CHH–Nam). δC (63 MHz, CDCl3, 298 K) 151.3,
145.9 (Npz–C), 133.3–125.9 (Ph), 103.6 (Npz–CH), 52.3 (Npz–
CH2–CH2–Nam), 47.3 (Npz–CH2–CH2–Nam). m/z (ESI+) 614.1
(100%, [PdCl2(L1) − HCl − Cl]+).
N
am), 3.02 (dddd, 2H, 2J 13.28, 3J 8.61, 3J 3.00, 3J 5.62,
Npz–CH2–CHH–Nam). δC (63 MHz, CD3CN, 298 K) 157.2,
149.1 (Npz–C), 131.5–128.0 (Ph), 108.5 (Npz–CH), 51.5 (Npz–
CH2–CH2–Nam), 50.3 (Npz–CH2–CH2–Nam). m/z (ESI+) 614.1
(100%, [PdCl(L1) − HCl]+).
Coupling constants for complex 3 were obtained with the aid
of the g NMR program.[31]
Synthesis of the Complex [PdCl(L2)](BF4) (4)
Compound 2 (0.124 g, 64%). (Found: C 60.19, H 4.85,
N 9.80. C36H35Cl2N5Pd (715.0) requires C 60.47, H 4.93,
N 9.79%). Conductivity (ꢀ−1 cm2 mol−1, 1.0 × 10−3 M in
methanol) 128.0. Conductivity (ꢀ−1 cm2 mol−1, 1.3 × 10−3 M
in acetonitrile) 153.6. νmax (KBr)/cm−1 ν(C–H)ar 3055, ν(C–
H)al 2922, ν(C=C)ph 1605, [ν(C=C)pz, ν(C=N)pz] 1552,
[δ(C=C)ar, δ(C=N)ar] 1480, 1467, δ(C–H)ip 1035, δ(C–H)oop ar
763, 696. νmax (polyethylene)/cm−1 ν(Pd–N) 504, ν(Pd–Cl) 348.
δH (250 MHz, CDCl3, 298 K) 8.00 (m, 4H, ortho-Ph), 7.70–
A solution of ligand L2 (0.15 g, 0.27 mmol) in dry acetonitrile
(10 mL) was added to a solution of [PdCl2(CH3CN)2] (0.070 g,
0.27 mmol) in the same solvent (10 mL). Under continuous stir-
ring, NaBF4 (0.030 g, 0.27 mmol) was added to the solution and
after 30 min of reaction, the solution was filtered through a pad
of Celite. The filtered solution was stirred for 30 min and then
the solvent was reduced to roughly 5 mL. Dry and cool diethyl
ether (3 mL) was added to induce precipitation. The yellow solid
was filtered off, washed twice with 3 mL of dry and cool diethyl
ether, and dried under vacuum.
2
7.23 (m, 16H, Ph), 6.63 (s, 2H, Npz–CH), 5.66 (ddd, 2H, J
15.86, 3J 2.09, 3J 11.09, Npz–CHH–CH2–Nam), 5.10 (ddd,
2H, 2J 15.86, 3J 1.73, 3J 4.33, Npz–CHH–CH2–Nam), 4.66
Compound 4 (0.130 g, 63%). (Found C 56.66, H 4.33,
N 9.13. C36H35BClF4N5Pd (766.4) requires C 56.42, H 4.60,
N 9.14%). Conductivity (ꢀ−1 cm2 mol−1, 1.1 × 10−3 M in ace-
tonitrile) 121.3. νmax (KBr)/cm−1 ν(C–H)ar 3047, ν(C–H)al
2954, 2854, ν(C=C)ph 1607, [ν(C=C)pz, ν(C=N)pz] 1552,
[δ(C=C)ar, δ(C=N)ar] 1482, 1470, ν(B–F) 1062, δ(C–H)oop ar
761, 695. νmax (polyethylene)/cm−1 ν(Pd–N) 521, ν(Pd–Cl) 341.
2
3
3
(ddd, 2H, J 14.60, J 2.09, J 11.09, Npz–CH2–CHH–Nam),
2
3
3
3.15 (ddd, 2H, J 14.60, J 1.73, J 4.33, Npz–CH2–CHH–
am), 3.10 (q, 2H, 3J 6.9, Nam–CH2–CH3), 1.75 (t, 3H, 3J
N
6.9, Nam–CH2–CH3). δC (63 MHz, CDCl3, 298 K) 157.4, 149.9
(Npz–C), 131.6–127.2 (Ph), 108.6 (Npz–CH), 62.4, 62.1 (Npz–
CH2–CH2–Nam, Nam–CH2–CH3), 51.6 (Npz–CH2–CH2–Nam),
14.1 (Nam–CH2–CH3). m/z (ESI) 678.1 (100%, [PdCl(L2)]+).
Coupling constants for complexes 1 and 2 were obtained with
the aid of the g NMR program.[31]
3
δH (250 MHz, CD3CN, 298 K) 8.14 (d, 4H, J 7.8, ortho-Ph),
7.61–7.45 (m, 16H, Ph), 6.85 (s, 2H, NpzCH), 5.56 (ddd, 2H,
2J 15.80, 3J 1.27, 3J 11.40, Npz–CHH–CH2–Nam), 4.69 (ddd,
2H, 2J 15.80, 3J 3.70, 3J 1.74, Npz–CHH–CH2–Nam), 3.23
2
3
3
(ddd, 2H, J 14.61, J 1.27, J 3.70, Npz–CH2–CHH–Nam),
2
3
3
Synthesis of the Complex [PdCl(L1)](BF4) (3)
3.16 (ddd, 2H, J 14.61, J 11.40, J 1.74, Npz–CH2–CHH–
am), 3.38 (q, 2H, 3J 7.0, Nam–CH2–CH3), 1.42 (t, 3H, 3J
A solution of AgBF4 (0.052 g, 0.27 mmol) in methanol (5 mL)
was added dropwise with vigorous stirring to a solution
of L1 (0.138 g, 0.27 mmol) and [PdCl2(CH3CN)2] (0.070 g,
0.27 mmol) in 15 mL of a dichloromethane/methanol mixture
(5/1). The reaction was carried out in the dark to prevent reduc-
tion of AgI to Ag0. After 30 min, stirring was stopped, and AgCl
was filtered off through a pad of Celite. The solution was then
stirred for 12 h. Afterwards, the volume of the resultant solution
was reduced to roughly 5 mL, and the product precipitated as a
pale yellow solid. This solid was filtered off, washed twice with
diethyl ether (5 mL), and dried under vacuum.
N
7.0, Nam–CH2–CH3). δC (63 MHz, CD3CN, 298 K) 157.8, 150.3
(Npz–C), 132.3–128.8 (Ph), 108.8 (Npz–CH), 61.9, 62.7 (Npz–
CH2–CH2–Nam, Nam–CH2–CH3), 51.5 (Npz–CH2–CH2–Nam),
11.7 (Nam–CH2–CH3). m/z (ESI+) 678.1 (100%, [PdCl(L2)]+).
Coupling constants for complex 4 were obtained with the aid
of g NMR program.[31]
Crystal Structure Determination for Compound
[PdCl(L2)](BF4) (4)
Compound 3 (0.153 g, 77%). (Found: C 55.22, H 4.07, N
9.40. C34H31BClF4N5Pd (738.3) requires C 55.31, H 4.23,
N 9.49%). Conductivity (ꢀ−1 cm2 mol−1, 8.9 × 10−4 M in
Suitable crystals for X-ray diffraction of compound [PdCl(L2)]
(BF4) were obtained through crystallization from
dichloromethane/diethyl ether (1/1) mixture.
a

New Palladium(ii) Complexes
481
A prismatic crystal was selected and mounted on a MAR345
diffractometer with an image plate detector. Unit cell parameters
were determined from 302 reflections (3 < θ < 31◦) and refined
by the least-squares method.
The structure was solved by Direct methods, using a
SHELXS-97 computer program,[48] and refined by a full-
matrix least-squares method with a SHELXL-97 computer
program[49] using 33079 reflections (very negative intensi-
ties were not assumed). The function minimized was ꢁω
[11] M. C. Castellano, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía,
J. Ros, Inorg. Chim. Acta 2008, 361, 2923. doi:10.1016/
J.ICA.2008.02.059
[12] M. C. Castellano, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía,
J. Ros, Inorg. Chim. Acta 2008, 361, 2491. doi:10.1016/
J.ICA.2008.01.016
[13] A. Pañella, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía, J. Ros,
Eur. J. Inorg. Chem. 2006, 1678. doi:10.1002/EJIC.200501056
[14] A. Pañella, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía,
J. Ros, Inorg. Chim. Acta 2006, 359, 4477. doi:10.1016/J.ICA.
2006.05.046
||Fo|2 − |Fc|2|2, where ω = [σ2(I) + (0.0427P)2 + 0.5925P]−1
,
and P = (|Fo|2 + 2|Fc|2)/3. All H atoms were computed and
refined, using a riding model, with an isotropic temperature fac-
tor equal to 1.2 times the equivalent temperature factor of the
atom that was linked.
[15] G. Zamora, J. Pons, J. Ros, Inorg. Chim. Acta 2004, 357, 2899.
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0682(200211)2002:11<2999::AID-EJIC2999>3.0.CO;2-A
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[20] W. G. Haanstra, W. L. Driessen, R. A. G. de Graff, G. C. Sebregts,
J. Suriano, J. Reedijk, U. Turpeinen, R. Hämäläinen, J. S. Wood, Inorg.
Chim. Acta 1991, 189, 243. doi:10.1016/S0020-1693(00)80196-6
[21] E. Pretch, T. Clerc, J. Seibl, W. Simon, Tables of Determination of
Organic Compounds. 13C-NMR,1H-NMR, IR, MS, UV/VIS, Chemical
Laboratory Practice 1989 (Springer: Berlin).
C36H35ClBN5F4Pd, M 766.35, colour yellow, monoclinic,
space group P21/n, a 13.920(5), b 18.275(5), c 14.543(4) Å, β
116.13(2)◦, U 3321.5(18) Å3, Z 4, D 1.533 Mg m−3, µ(MoKα
)
0.697 mm−1, F(000) 1560,T 293(2) K, hkl ranges −20 ≤ h ≤ 20,
−26 ≤ k ≤ 27, −21 ≤ l ≤ 21, wavelength 0.71073 Å, 2θ range
2.72◦ to 32.42◦, 33079 reflections, 9452 unique (Rint 0.0301),
completeness to θ 29.97◦ 94.7%, data/restraints/parameters
9452/2/433, goodness-of-fit on F2 1.154, R1 0.0424 (7721
reflections, I > 2σ(I)), wR2 0.0962, R1 0.0600 (all data), wR2
0.1027 (all data), largest diff. peak and hole 0.672 and
−0.831 e Å−3
.
The crystal data have been deposited with the Cambridge
Crystallographic Data Centre (www.htpp://ccdc.cam.ac.uk;
708273).
[22] D. H. Williams, I. Fleming, Spectroscopic Methods in Organic
Chemistry 1995 (McGraw-Hill: London, UK).
[23] S. Komiya, Synthesis of Organometallic Compounds: A Practice
Guide 1997 (Wiley & Sons: New York, NY).
[24] W. J. Geary, Coord. Chem. Rev. 1971, 7, 81. doi:10.1016/S0010-
8545(00)80009-0
[25] L. K. Thompson, F. L. Lee, E. J. Gabe, Inorg. Chem. 1988, 27, 39.
doi:10.1021/IC00274A010
[26] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordi-
nation Compounds 1997 (Wiley & Sons: New York, NY).
[27] J. García-Antón, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Eur. J.
Inorg. Chem. 2003, 3657.
Accessory Publication
Tableswithchemicalshiftsandcouplingconstantsforcomplexes
1–4, experimental and theoretical isotopic distribution ESI+ MS
spectra for compound 1, experimentally determined and simu-
lated spectra for compounds 2–4, and a figure of π–π stacking
interactions in the [PdCl(L2)]+ cation are available from the
Journal’s website.
[28] J. García-Antón, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Eur. J.
Inorg. Chem. 2002, 3319. doi:10.1002/1099-0682(200212)2002:12
<3319::AID-EJIC3319>3.0.CO;2-L
[29] J. García-Antón, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Eur. J.
Inorg. Chem. 2003, 2992. doi:10.1002/EJIC.200300035
[30] J. Llop, C. Masalles, C. Viñas, F. Teixidor, R. Sillampää, R. Kivekäs,
Dalton Trans. 2003, 556. doi:10.1039/B211860M
[31] P. H. M. Budzelaar, g NMR–Version 4.0. IvorySoft 1997 (Cherwell
Scientific: Oxford, UK).
[32] F. A. Allen, Acta Crystallogr. 2002, B58, 380.
[33] V. Montoya, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim.
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[34] J. A. Pérez, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim.
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[35] A. Boixassa, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim.
Acta 2004, 357, 733. doi:10.1016/J.ICA.2003.06.015
Acknowledgement
Supportby theSpanishMinisterio deEducación yCultura(projectCTQ2007
63913/BQU) is gratefully acknowledged.
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