Palladium(II) and platinum(II) complexes with N1-hydroxyethyl-3,5-pyrazole derived ligands

Article abstract of DOI:10.1016/j.ica.2012.07.027

Reaction of the ligands 2-(5-methyl-3-phenyl-1H-pyrazol-1-yl)ethanol (L1) and 2-(3-methyl-5-phenyl-1H-pyrazol-1-yl)ethanol (L2) with [MCl ₂(CH₃CN)₂] (M = Pd(II), Pt(II)) gave the complexes trans-[MCl₂L₂] (M = Pd(II) and Pt(II), L = L1, L2). The new complexes were characterised by elemental analyses, conductivity measurements, mass spectrometry, IR, ¹H and ¹³C{ ¹H} NMR spectroscopies. The crystal and molecular structures of the ligand L2 and the complexes trans-[PdCl₂L₂] (L = L1, L2) were resolved by X-ray diffraction. Both palladium complexes consisted on monomeric trans-[PdCl₂L₂] (L = L1, L2) species and molecular packing is determined by intermolecular hydrogen bonding interactions. The NMR spectra of the complexes [PdCl₂L₂] (L = L1, L2) in CDCl₃ solution, is consistent with a very slow rotation of the pyrazolic ligands around the Pd-N bond, so that two conformational isomers can be observed in solution (syn and anti). Different behaviour was observed for complexes [PtCl₂L₂] (L = L1, L2), for which only the anti isomer was detected in CDCl₃ solution at room temperature.

Full text of DOI:10.1016/j.ica.2012.07.027

Inorganica Chimica Acta 394 (2013) 21–30
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Inorganica Chimica Acta
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Palladium(II) and platinum(II) complexes with N1-hydroxyethyl-3,5-pyrazole
derived ligands
José A. Perez a, Vanessa Montoya a, José A. Ayllon a, Mercè Font-Bardia b,c, Teresa Calvet b,c, Josefina Pons a,
⇑
a Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
b Cristal lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain
c Unitat de Difracció de RX, Centres Científics i Tecnològics de la Universitat de Barcelona, Solé i Sabaris 1-3, 08028, Barcelona, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Reaction of the ligands 2-(5-methyl-3-phenyl-1H-pyrazol-1-yl)ethanol (L1) and 2-(3-methyl-5-phenyl-
1H-pyrazol-1-yl)ethanol (L2) with [MCl2(CH3CN)2] (M = Pd(II), Pt(II)) gave the complexes trans-[MCl2L2]
(M = Pd(II) and Pt(II), L = L1, L2).
The new complexes were characterised by elemental analyses, conductivity measurements, mass spec-
trometry, IR, 1H and 13C{1H} NMR spectroscopies. The crystal and molecular structures of the ligand L2
and the complexes trans-[PdCl2L2] (L = L1, L2) were resolved by X-ray diffraction. Both palladium com-
plexes consisted on monomeric trans-[PdCl2L2] (L = L1, L2) species and molecular packing is determined
by intermolecular hydrogen bonding interactions.
Received 23 March 2012
Received in revised form 2 July 2012
Accepted 26 July 2012
Available online 11 August 2012
Keywords:
N-Hydroxyalkylphenylpyrazole
Regioisomers
The NMR spectra of the complexes [PdCl2L2] (L = L1, L2) in CDCl3 solution, is consistent with a very slow
rotation of the pyrazolic ligands around the Pd–N bond, so that two conformational isomers can be
observed in solution (syn and anti). Different behaviour was observed for complexes [PtCl2L2] (L = L1,
L2), for which only the anti isomer was detected in CDCl3 solution at room temperature.
Ó 2012 Elsevier B.V. All rights reserved.
Palladium(II)
Platinum(II)
Crystal structures
1. Introduction
polyether, tioether). These pyrazole derivatives ligands coordinate
to palladium and platinum only through the azine nitrogen, acting
Coordination chemistry of palladium(II) and platinum(II) com-
plexes with heterocyclic ligands with two potential donor atoms
is one of the research areas that has undergone a fast development
during the last years [1]. Among all the examples reported so far,
those containing pyrazole derivatives are especially attractive
because they have multiple applications. For example, similar com-
plexes (pyridylpyrazole ligands with Pt(II)) have show greater
antitumor activity and lower toxicity than the common
cis-[PtCl2(NH3)2] complex [2]. Applications of palladium and
platinum complexes including pyrazolic ligands extend also to
macromolecular chemistry [3] and homogeneous catalysis [4].
Properties of the pyrazole ligand can be modified through sub-
stitution of the protons, yielding a great diversity of pyrazolyl
derivatives. The nature of the substituents, size and functionaliza-
tion, determines the chemical and structural characteristics of me-
tal complexes formed with these pyrazole derivative ligands.
We have previously studied 1,3,5-substituted pyrazole derived
ligands, including only substituents without donor atoms (alkyl,
phenyl), or with donor atoms with low coordination power (ether,
thus as monodentate ligand. This is the case of the complexes with
stoichiometry [MCl2(Npz)2] (M = Pd(II) or Pt(II), pz = 1,3,5-substi-
tuted pyrazole ligand). In these complexes, it can exist two differ-
ent isomers: cis or trans which are defined as a function on the
arrangement of the chlorine or pyrazolyl ligands [5]. For all the pal-
ladium complexes the trans isomer was obtained, as it minimizes
the steric hindrance between the two pyrazolyl ligands, also the
NMR studies in solution have proved the existence of conforma-
tional diastereoisomers, anti and syn, defined by the relative dispo-
sition of the N1 attached group, while all analysed crystal
structures correspond to the anti isomer, suggesting that this iso-
mer is the most stable one in solid state. In the case of platinum
complexes, cis and trans isomers have been found in the solid state
[5b–d]. This difference in the disposition of the chlorine atoms be-
tween Pd(II) and Pt(II) complexes with similar ligands had already
been observed in the literature [6,7], and generally, it is explained
by the considerable higher labiality of ligand–Pd(II) bonds com-
pared to ligand–Pt(II).
In particular, in this work we have reported the synthesis and
structural characterisation of new palladium(II) and platinum(II)
complexes with N1-hydroxyethyl-3,5-substituted pyrazole li-
gands. Moreover, in order to see whether the hindered rotation
around the metal–N bond in solution is caused by the bulk substit-
uents in 3,5-disposition, by the lengths of the N1-substituents or
⇑
Corresponding author. Address: Departament de Química, Facultat de Ciències,
Universitat Autònoma de Barcelona, Bellaterra-Cerdanyola, 08193 Barcelona, Spain.
Fax: +34 93 581 31 01.
E-mail address: Josefina.Pons@uab.es (J. Pons).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.07.027

22
J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
by the nature of the metal, the related Pd(II) and Pt(II) isomer for-
mation with these ligands have been investigated by NMR and
compared with previous results obtained with similar complexes.
spectroscopy, mass spectrometry. L2 regioisomer was further char-
acterised by X-ray diffraction. The assignment of each one of the
regioisomers was confirmed by NOESY experiments. Regioisomer
L1 presents NOE-interactions between the protons of the hydroxy-
alkyl chain and the methyl group. For L2, NOE-interactions be-
tween the protons of hydroxyalkyl chain and the phenyl group
are observed.
2. Results and discussion
2.1. Synthesis and general characteristics of the ligands
The more distinctive signals in the 1H NMR are those assigned
to ortho-phenyl hydrogen at d = 7.76 ppm (3J = 5.1 Hz) (L1), and
d = 7.42 ppm (3J = 4.7 Hz) (L2) as doublets and the assigned to the
pyrazolic hydrogen at d = 6.19 ppm (L1) and 5.96 ppm (L2). Other
signals attributed to the metha- and para-phenyl hydrogens are
present as a multiplete. The 13C{1H} NMR spectra display the sig-
nals at d = 102.4 ppm (L1) and 105.6 ppm (L2), attributable to the
CH of the pyrazole [11]. In the mass spectrum (ESI(+)-MS) of L1
and L2 ligands, one signal is observed at 203 (100%), attributable
to [L+H]+ (L = L1, L2).
The structure of L2 ligand was confirmed by single crystal X-ray
diffraction from prismatic crystals obtained by the slow evapora-
tion of an ethyl acetate solution of a mixture of L1 and L2 ligands.
The quality of crystal was poor but the X-ray diffraction analysis
could be carried out and clearly revealed the structure of the
ligand.
1-Phenyl-1,3-butanedione [8] was the precursor for the synthe-
sis of the ligands. This b-dione was prepared by Claisen condensa-
tion of ethyl acetate and acetophenone using sodium ethoxide
(NaOEt) as base and dry toluene as solvent [9]. Treatment of this
b-dione with 2-hydroxyethylhydrazine in absolute ethanol at room
temperature during 16 h produced two regioisomers, 2-(5-methyl-
3-phenyl-1H-pyrazol-1-yl)ethanol (L1) and 2-(3-methyl-5-phenyl-
1H-pyrazol-1-yl)ethanol (L2) in a 98% yield (Scheme 1). The higher
reaction time required for this synthesis compared with similar
ones described in the literature is probably due to both electronic
and steric hindrance effects of the methyl group [10]. The separa-
tion of the two regioisomers was carried out by silica column chro-
matography using ethyl acetate as eluent. A 50:50 regioisomer
ratio (L1:L2) was calculated through the integration of the pyrazol-
ic proton signals in the 1H NMR spectrum. When the same reaction
was carried out at low temperature (ꢀ84 °C), the formation of the
kinetic regioisomer (L2) was favoured and the regioisomer ratio
was 24:76 (L1:L2).
ORTEP picture of L2 with the atom numbering scheme is shown
in Fig. 1. The phenyl group is twisted with respect to the pyrazole
and the asymmetric unit consists of four molecules that differ in
the angles between these rings (42.7(2)°, 44.7(2)°, 38.1(2)° and
40.3(2)°), respectively. Each molecule is linked to other two via
Both regioisomers were characterised by elemental analyses,
mass spectrometry, IR, 1H, 13C{1H}, COSY, HSQC and NOESY NMR
O
CH3
+
H3C
O
CH3
(
ethyl acetate)
O
(
Acetophenone)
1) NaOEt (toluene)
16h, r.t.
CH3
( β
−
dione)
O
O
1) NH2NHCH2CH2OH
CH3
CH3
+
N
N
N
N
(L1)
(L2)
HO
OH
[MCl2(CH3CN)2]
CH3
[MCl2(CH3CN)2]
CH3
N
N
N
N
Cl
Cl
OH
M
HO
M
HO
Cl
Cl
OH
N
N
N
N
H3C
H3C
(1),
(3)
(2),
(4)
Pt(II)
M = Pd(II)
Pt(II)
M = Pd(II)
Scheme 1.

J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
23
Fig. 1. ORTEP view of the L2 asymmetric unit with atom labelling scheme. Thermal ellipsoids were drawn at 50% probability. Hydrogen atoms are omitted for clarity.
hydrogen bonds between the proton of the alcohol (CH2–CH2–OH)
and the free pair electrons of the pyrazolic nitrogen (O–Hꢁ ꢁ ꢁN). The
O–Hꢁ ꢁ ꢁN distances and the angles showed in Table 1 are in agree-
ment with other values described in the literature [6,12]. These
interactions give as a result a supramolecular structure in a zig-
zag infinite chains extending in the a-axis direction (Fig. 2).
The pyrazole rings of the adjacent molecules are approximately
parallel (14.5(2)° and 15.7(2)°), whereas the phenyl rings are al-
most perpendicular (82.8(2)° and 81.8(2)°) in such way that the
supramolecular structure is also stabilized by C–Hꢁ ꢁ ꢁ
p interactions
involving the phenyl rings. The C–Hꢁ ꢁ ꢁCg contact distances be-
tween the H atoms of a phenyl groups and the centroid of the
neighbouring phenyl rings are: C(9B)–H(9B)ꢁ ꢁ ꢁCg(4) 2.87 Å, sym-
metry code ꢀx, 1 ꢀ y, 1 ꢀ z; C(11C)–H(11C)ꢁ ꢁ ꢁCg(2) 2.89 Å, symme-
try code 1 ꢀ x, 2 ꢀ y, ꢀz; C(12A)–H(12A). . .Cg(6) 2.94 Å, symmetry
code 1 + x, y, z; Cg(4), Cg(2) and Cg(6) are the centroids of the phe-
nyl rings numbered C(7A)–C(12A), C(7)–C(12) and C(7B)–C(12B),
respectively.
Table 1
Distances (Å) and angles (°) of hydrogen bonds of L2.
O–Hꢁ ꢁ ꢁN
O–H (Å) O–Hꢁ ꢁ ꢁN (Å) Oꢁ ꢁ ꢁN (Å) O–Hꢁ ꢁ ꢁN (°)
O(1)–H(1)ꢁ ꢁ ꢁN(2A)i
0.82
2.18
2.13
2.13
2.16
2.924(4)
2.850(4)
2.801(4)
2.853(4)
151
146
140
143
O(1A)–H(1A1)ꢁ ꢁ ꢁN(2C)i 0.82
O(1C)–H(1C)ꢁ ꢁ ꢁN(2B)i
O(1)–H(1B1)ꢁ ꢁ ꢁN(2)ii
0.82
0.82
Symmetry code: (i) 1 ꢀ x, 1 ꢀ y, 1 ꢀ z; (ii) ꢀx, 1 ꢀ y, 1 ꢀ z.
2.2. Synthesis and general characterisation of complexes
The reaction of the ligands (L1, L2) with [MCl2(CH3CN)2]
(M = Pd(II) [13] or Pt(II) [14] in acetonitrile, yielded [MCl2(L1)2]
(M = Pd(II) (1), Pt(II) (3)) and [MCl2(L2)2] (M = Pd(II) (2), Pt(II)
(4)) complexes. Reactions were performed with 1 M:1 L or
1 M:2 L molar ratios and the same results were obtained. Com-
pounds 1–4 were characterised by elemental analyses, mass spec-
trometry, conductivity measurements, IR and 1D and 2D NMR
spectroscopies. The NMR signals were assigned by reference to
the literature [11] and from DEPT, COSY, HSQC and NOESY spectra.
Single crystal X-ray diffraction was also obtained for the palladium
compounds, 1 and 2. For all complexes, the elemental analyses
agreed with the formula [MCl2L2] (M = Pd(II), Pt(II); L = L1, L2).
The positive ionisation spectra (ESI(+)-MS), of complexes 1–4
showed peaks with m/z values of 546 (100%), for 1 and 2, attribut-
able to [PdClL2]+ (L = L1, L2) and 635 (100%) for 3 and 4, attribut-
able to [PtClL2]+ (L = L1, L2). The observed molecular peaks of the
cations exhibit the same isotope distribution as predicted theoret-
ically. Conductivity values of 10ꢀ3 M samples in methanol, for all
Fig. 2. View of the infinite 3D-structure formed by the different units of L2 bonded
by hydrogen bonds.

24
J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
compounds, were in agreement with the presence of non-electro-
lyte compounds [15].
to be possible due to higher Pt–N bond rigidity in comparison with
Pd–N.
IR spectra of complexes 1–4 in KBr pellets display absorptions
of the N-hydroxyalkylmethylphenylpyrazole ligands. For all com-
plexes, the most characteristic bands are those attributable to the
With these results it seems that the hindrance to rotation
around metal–ligand bonds is predominantly controlled by the
metal but the influence of steric factor is not negligible [18]. Other
precedents in the literature also show that the reactivity of pyraz-
olic ligands with Pt(II) yields different results to those obtained
with Pd(II) [5b,5d,7]. It is well known that Pd(II) is more reactive
than Pt(II) complexes, for example in the literature it is found that
palladium complexes interconvert more readily than platinum
analogues [19]. NMR studies of rotational barriers for metal–N
complexes have also shown that in Pt(II) complexes, energy barri-
ers are higher than in Pd(II) complexes [18]. These experimental
observations were supported by ab initio calculations of model
complexes containing Pd–N and Pt–N bonds, which reveal that
pyrazole and phenyl groups: [m(C@C), m
(C@N)] (1559–1554 cmꢀ1),
[d(C@C), d(C@N)] (1500–1437 cmꢀ1), d(C–H)oop (812–768 cmꢀ1). It
is worth noting that, in the IR spectra of the four compounds, a typ-
ical broad band appeared between 3448 and 3309 cmꢀ1 showing
the presence of the alcohol group m(O–H). The shape and position
of this band suggests that hydroxyl group participates in hydrogen
bonding interactions [16]. IR spectra of all complexes, between 600
and 200 cmꢀ1, were also recorded. The complexes 1 and 2 showed
the
plexes 3 and 4 showed the
respectively [17]. Moreover, these complexes displayed one band
between 355 and 344 cmꢀ1, attributable to
(M–Cl) (M = Pd(II),
m
(Pd–N) bands at 487 and 494 cmꢀ1, respectively, and com-
m
(Pt–N) bands at 458 and 462 cmꢀ1
,
the nitrogen metal
plexes, resulting in a higher energy rotation barrier [20]. Despite
the fact that pyrazole ligands are poor- -acceptors [21], the exper-
imental finding suggests that the -effects can be significant in the
p–r interactions is stronger for Pt(II) com-
m
Pt(II)), which are typical of compounds with a trans disposition
of the chlorine atoms around the metal [17].
p
p
The NMR spectra of 1–4 were acquired using CDCl3 as solvent.
1H NMR and 13C{1H} NMR spectra for complexes 1 and 2 showed
two set of signals for many protons, suggesting the presence of
conformational isomers in solution, in an intensity ratio of approx-
imately 1:0.8 in the case of 1 and 1:0.4 in 2. Our previous work also
proved that the two species proposed in these cases are the anti
and the syn isomers, respectively, concerning the position of the
two carbon chain [5].
Different characteristics of the palladium complexes determine
the proportion of the different isomers in solution. When the N-al-
kyl chain increases its length, the less stable isomer (syn) decreases
its concentration in solution [5c]. The presence of the syn and the
anti isomers is not due to steric factors caused by the substitution
(hydrogen, methyl, phenyl or pyridyl) in positions 3 and 5 of the
pyrazolic ring [5] (Fig. 3).
In this work, it seemed that the hindrance rotation around me-
tal–ligand bonds, giving these two isomers in solution, was pre-
dominantly controlled by the position of the hydroxyalkyl chain
in the pyrazole ring. In both complexes the less stable isomer
(syn) was present in a minor concentration and this difference
was especially important for complex 2.
The presence of two isomers in solution was not observed in
complexes [PtCl2L2] (L = L1(3), L2(4)), which showed a unique set
of signals for each type of proton and carbon, corresponding to
the anti conformational isomer.
control of the preferential formation of the rotational
diastereoisomers.
Other observed bands are those attributable to Hpz, which ap-
pear between 6.33 and 6.03 ppm. These values show a displace-
ment compared to the same signal for the free ligands (6.19 ppm
(L1), 5.96 ppm (L2)). The bands attributable to ethylene protons
of the Npz–CH2–CH2–OH chains appear as two triplets between
5.41 and 4.75 ppm and 4.31 and 3.88 ppm, with 1H–1H coupling
constants between 6.6 and 5.7 Hz.
In complexes 3 and 4, the signal attributable to the proton of the
alcohol group (OH) is not observed. However in complexes 1 and 2,
this signal appears as a broad band between 3.14 and 2.84 ppm (1)
and 2.64 and 2.62 ppm (2).
Additional 195Pt{1H} NMR experiments for complexes 3 and 4 at
298 K, presents only one band for each complex. For these com-
plexes, the signals appeared at ꢀ2189 and ꢀ2152 ppm, respec-
tively. These values are in the range described in the literature
for complexes with [PtCl2N2] core (ꢀ2279, ꢀ1198 ppm) [5e,7b,22].
2.3. Crystal and molecular structures for compounds trans-
[PdCl2(L1)2](1) and trans-[PdCl2(L2)2](2)
The structures of 1 and 2 were determined by single crystal X-
ray diffraction.
ORTEP pictures and selected bond lengths (Å) and bond angles
(°) are shown in Figs. 4 and 5 and Table 2. Slow evaporation of chlo-
roform solution of 1 or 2 yielded prismatic orange crystals. The
quality of the crystals of complex 2 was not optimal. Other at-
tempts of crystallisation were done, but no single crystals of better
quality were obtained. Despite this limitation and the molecular
disorder of hydroxyethyl group, the structural refinement pre-
ceded reasonably well, all parameters converging satisfactorily
and no abnormal residual electron density being evident.
The 1H NMR spectra of complexes 3 and 4, at variable temper-
ature (298–233 K) did not show any splitting or broadening of sig-
nals, which is in agreement with the presence of only one species
in solution. In 3 and 4, the anti nature of the isomers was confirmed
by NOESY experiments. The complex 3, showed NOE-interaction
between CH3 group and CH2–CH2–OH, and in 4, we observed
NOE-interaction between ortho-Hph and CH2–CH2–OH chain. In
these compounds, the rotation around the Pt–N bond seemed not
CH3
CH3
N
N
N
N
Cl
N
Cl
HO
Pd
Pd
Cl
Cl
OH
OH
N
N
N
OH
3C
H
CH3
Fig. 3. The conformational isomers existing in solution due to hindered rotation around the Pd–N bond at room temperature for compounds 1 and 2.

J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
25
Fig. 4. ORTEP diagram of complex [PdCl2(L1)2] (1) showing the atom labelling scheme. 50% Amplitude displacement ellipsoids are shown. Hydrogen atoms are omitted for
clarity.
Fig. 5. ORTEP diagram of complex [PdCl2(L2)2] (2) showing an atom labelling scheme. 50% Amplitude displacement ellipsoids are shown. Hydrogen atoms are omitted for
clarity.
The crystal structures of 1 and 2, consist of discrete Pd(II) mol-
Table 2
0
ecules connected by hydrogen bonds. The Pd(II) is linked to two li-
Selected bond lengths (AÅ) and bond angles (°) for [PdCl2(L1)2] (1) and [PdCl2(L2)2] (2).
gand molecules (L1 or L2) via j
1-Npz and finishes its coordination
1
2
with two chlorine atoms in a trans disposition. The Pd(II) centre
presents a typical square planar geometry (with a slight tetrahe-
dral distortion) in which the largest deviation from the mean coor-
dination plane is ꢀ0.004(1) Å for 1, and 0.006(1) Å for 2. The
palladium centre is approximately coplanar with the four coordi-
nating atoms. The values of N–Pd–N and Cl-Pd–Cl angles are be-
tween 177.2(2)° and 179.7(1)°. Moreover, the values of N–Pd–Cl
angles are between 88.6(1)° and 90.3(2)°. The cis angles N–Pd–Cl
deviate from the ring angle in ꢂ1°, the deviation is the same order
in the similar complexes [8].
Pd–N(2)
Pd–N(4)
Pd–Cl(1)
Pd–Cl(2)
N(2)–Pd–N(4)
N(2)–Pd–Cl(1)
N(4)–Pd–Cl(1)
N(2)–Pd–Cl(2)
N(4)–Pd–Cl(2)
Cl(1)–Pd–Cl(2)
1.992(5)
1.998(5)
2.279(2)
2.282(2)
178.9(2)
90.3(2)
90.3(2)
89.8(2)
89.7(2)
179.7(1)
Pd–N(2)
Pd–N(4)
Pd–Cl(1)
Pd–Cl(2)
N(2)–Pd–N(4)
N(2)–Pd–Cl(1)
N(4)–Pd–Cl(1)
N(2)–Pd–Cl(2)
N(4)–Pd–Cl(2)
Cl(1)–Pd–Cl(2)
2.010(5)
2.007(5)
2.274(2)
2.318(2)
177.2(2)
89.4(1)
88.6(1)
90.4(1)
91.7(1)
179.1(1)

26
J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
Table 4
In both complexes, ligands (L1 and L2, respectively) are not pla-
Geometrical parameters of C–Hꢁ ꢁ ꢁ
p interactions in complex 1.
nar. The phenyl groups twisted with respect to the pyrazole
groups. The dihedral angles between ph and pz are 73.5(3)° and
69.9(4)° for 1, and 84.2(4)° and 58.6(3)° for 2. The ph–pz dihedral
angles are in the interval described in the literature [5a,5c,9a,23].
The hydroxyethyl group, bonded to Npz atom, moves away from
the chelating plane giving a torsion angle N–C–C–O, 80.7(9)° for
1 and 61.4(8)° and 63.3(8)° for 2, respectively. These values are
the same order than that found in other complexes described in
the literature [5e,24]. However, it has to be remarked that in the
complex 1 the hydroxyethyl group is disordered over two orienta-
tions with site-occupancy factors of 0.634(9) and 0.366(9).
The N1 and N3-hydroxyalkyl chains are in anti disposition with
respect of the plane of coordination of metal. The X-ray powder
diffraction pattern of 1 and 2 corroborate the presence of the un-
ique anti conformer in the solid state. The [PdCl2(Npz)2] core (con-
taining terminal chlorine atoms) is found in 69 complexes
described in the literature (39 of the complexes have trans geome-
try and thirty are cis) [6]. The values of distances Pd–N [1.992(5) Å,
1.998(5) Å; 2.007(5), 2.010(5) Å] and Pd–Cl [2.279(2) Å;
2.282(2) Å; 2.274(2) Å; 2.318(2) Å] are in agreement with the val-
ues described in the literature: Pd–N [1.989–2.042 Å] and Pd–Cl
[2.280–2.349 Å] [6].
C–Hꢁ ꢁ ꢁCg
Hꢁ ꢁ ꢁCg (Å)
D–Hꢁ ꢁ ꢁCg (Å)
3.70(1)
3.562(8)
3.635(8)
3.821(7)
3.792(8)
D–Hꢁ ꢁ ꢁA(°)
C(1)–H(1A)ꢁ ꢁ ꢁCg(4)i
C(9)–H(9)ꢁ ꢁ ꢁCg(2)ii
C(11)–H(11)ꢁ ꢁ ꢁCg(1)iii
C(17)–H(17)ꢁ ꢁ ꢁCg(4)iv
C(23)–H(23)ꢁ ꢁ ꢁCg(2)v
2.93
2.74
2.80
2.92
3.00
138
149
149
164
144
Symmetry codes for complex 1: (i) x, y, z; (ii) ꢀ + y, 1 ꢀ x, 1 + z; (iii) 1 ꢀ y, 1 + x,
3
4
4
4
4
4
1
3
3
3
ꢀ z; (iv) ꢀx, 3/2 ꢀ y, z; (v)
ꢀ y,
+ x,
4
ꢀ z.
4
4
4
Cg(4), Cg(2) and Cg(1) are the centroids of the phenyl and pyrazole rings numbered
C(7A)–C(12A), C(7)–C(12) and C(7B)–C(12B), respectively.
Nevertheless, the molecular packing and the intermolecular
interactions in complexes 1 and 2 are very different. The crystal
structure of complex 1 is tetragonal I41/a with 16 Pd(II) molecules
in the unit cell. Four molecules related by a 4-fold rotoinversion
axis form a tetrameric building unit through hydrogen bonding be-
tween the hydroxyethyl hydrogen atom at O1 and the oxygen atom
O2, symmetry code 3 ꢀ y, 3 4 + x, 3 4 ꢀ z. These tetrameric units are
4
further connected by hydrogen bonding involving the hydroxy-
ethyl hydrogen atom at O2 and the oxygen atom O1, symmetry
code ꢀ½ + x, y, ½ ꢀ z (see Table 3). Description of the hydrogen
bonds has been made with the position of the hydroxyethyl group
with the highest site-occupancy factor. Additional C–Hꢁ ꢁ ꢁCl hydro-
gen interactions connect the four-units along the [001] direction
Fig. 6. Crystal packing of complex 1, viewed along [100] direction. Dashed lines
represent hydrogen bonds.
Table 5
(Table 3). Furthermore, some weak C–Hꢁ ꢁ ꢁ
p interactions involving
Geometrical parameters of hydrogen bonds in complex 2.
the phenyl and pyrazole rings, play a role in the stabilization of the
crystal structure (see Table 4). These interactions and the coopera-
tive effect form a 3D supramolecular network where the molecules
are arranged in layers parallel to [001] direction and the phenyl
rings are nearly perpendicular in successive layers (Fig. 6).
O–Hꢁ ꢁ ꢁA
O–H (Å)
O–Hꢁ ꢁ ꢁA (Å)
1.90(2)
2.50
Oꢁ ꢁ ꢁA (Å)
2.747(8)
3.276(6)
O–Hꢁ ꢁ ꢁA (°)
156(2)
158
O(2)–H(2O)ꢁ ꢁ ꢁO(1)i
0.90(2)
0.82
O(1)–H(1O)ꢁ ꢁ ꢁCl(2)ii
Symmetry codes for complex 2: (i) ꢀ1 + x, y, z; (ii) 1 ꢀ x, ꢀy, 2 – z.
ꢀ
The crystal structure of complex 2 is triclinic P1 with two Pd(II)
molecules in the unit cell. The molecules are bonded by intermo-
lecular hydrogen bonds between the hydroxyethyl hydrogen atom
at O1 and the hydroxyethyl oxygen atom O2 of the translation re-
lated molecule (Table 5), forming chains that elongate in the direc-
tion of the a-axis (Fig. 7). These chains are connected by O–Hꢁ ꢁ ꢁCl
hydrogen bonding between the hydroxyethyl hydrogen atom at O2
and the chlorine atom Cl2 of the inversion symmetry related mol-
ecule (Table 5). These intermolecular interactions can be consid-
ered as ‘‘moderate’’ on the basis of the contact distances and
angles [25]. Furthermore the supramolecular structure is also sta-
interactions involving the phenyl rings. The
bilized by C–Hꢁ ꢁ ꢁ
p
C–Hꢁ ꢁ ꢁCg contact distances between the H atoms and the centroid
of the neighbouring phenyl ring are: C(1)–H(1A)ꢁ ꢁ ꢁCg(4) 2.94 Å,
symmetry code 1 + x, y, z; C(4)–H(4C)ꢁ ꢁ ꢁCg(4) 2.92 Å, symmetry
code x, ꢀ1 + y, z; Cg(4) is the centroid of the phenyl ring numbered
C(19)–C(24).
Table 3
Geometrical parameters of hydrogen bonds in complex 1.
D–Hꢁ ꢁ ꢁA
D–H (Å)
D–Hꢁ ꢁ ꢁA (Å)
Dꢁ ꢁ ꢁA (Å)
D–Hꢁ ꢁ ꢁA (°)
O(1)–H(1O)ꢁ ꢁ ꢁO(2)i
O(2)–H(2O)ꢁ ꢁ ꢁO(1)ii
C(4)–H(4B)ꢁ ꢁ ꢁCl(1)iii
C(4)–H(4C)ꢁ ꢁ ꢁCl(1)iv
C(16)–H(16B)ꢁ ꢁ ꢁCl(2)v
C(23)ꢀH(23)ꢁ ꢁ ꢁCl(2)vi
0.82
0.82
0.96
0.96
0.96
0.93
1.92
2.42
2.73
2.80
2.95
2.92
2.75(2)
3.21(2)
3.643(9)
3.704(9)
3.864(9)
3.639(9)
176
162
159
157
160
135
3
3
3
Symmetry codes for complex 1: (i)
ꢀ y,
+ x,
ꢀ z; (ii) ꢀ½ + x, y, ½ ꢀ z; (iii)
3 1 1
4
4
1
4
1
1
1
1
3
ꢀ y,
+ x,
ꢀ z; (iv) ꢀ + y,
ꢀ x, ꢀ + z; (v) ꢀ + y,
ꢀ x,
+ z; (vi)
4
4
4
3
4
4
4
4
4
4
Fig. 7. Crystal packing of complex 2, generated through hydrogen bonds and C–
3
3
ꢀ
+ y,
ꢀ x,
ꢀ z.
4
4
4
Hꢁ ꢁ ꢁp interactions. Dashed lines represent hydrogen bonds.

J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
27
4.2.1. Ligand L1
3. Conclusions
Yield: 57%. m.p = 20–25 °C. Anal. Calc. for C12H14N2O (202.2): C,
71.26; H, 6.98; N, 13.85. Found: C, 71.41; H, 6.72; N, 13.83%. MS(E-
SI+): m/z (%) = 225 (41) [L1+Na]+; 203 (100) [L1+H]+. IR (NaCl/
The ligands L1 and L2 reacts with [MCl2(CH3CN)2] (M = Pd(II),
Pt(II)) to give the trans-[MCl2L2] (M = Pd(II), Pt(II); L = L1, L2) com-
plexes. When M = Pd(II) and L = L1 (1), L2 (2), the NMR study is
consistent with a very slow rotation around Pd–N bond, so that
two conformationl isomers, anti and syn, can be observed in solu-
tion. The regioisomer ratio in solution is 1:0.8 (1) and 1:0.4 (2),
anti:syn, respectively. The position of N1-substituting, hydroxy-
ethyl chain is the responsible of the different intensity ratio ob-
served for two species. In the solid state only the anti isomer is
observed. A different behaviour is observed in the complexes
trans-[PtCl2L2] (L = L1, L2), which show only one signal for each
type of proton and carbon. The species present in solution is the
anti isomer. Several types of intermolecular interactions, specially
cmꢀ1):
(C@C),
m
(O–H) 3233,
m
(C–H)ar 3040,
m(C–H)al 2929, 2855,
[m
m(C@N)]ph 1654,
[
m
(C@C), (C@N)]pz 1604, [d(C@C),
m
d(C@N)] 1457, d(C–H)ip 1089, d(C–H)oop 697. 1H NMR (CDCl3 solu-
tion, 250 MHz, 298 K) d = 8.22–7.81 [m, 4H, Hph], 7.76 [d, 1H, 3J
5.1 Hz, Horto ph], 6.19 [s, 1H, CH(pz)], 4.28 [t, 2H, 3J 5.3 Hz, NCH2CH2-
OH], 4.13 [br, 1H, NCH2CH2OH], 4.06 [t, 2H, 3J 5.3 Hz, NCH2CH2OH],
2.80 [s, 3H, CH3]. 13C{1H} NMR (CDCl3 solution, 63 MHz, 298 K)
d = 151.3 [C–ph], 140.3 [C–CH3], 135.2 [C–Cph], 130.2–125.7
[Cph], 102.4 [CH(pz)], 61.5 [NpzCH2CH2OH], 50.1 [NpzCH2CH2OH],
11.9 [pz–CH3].
4.2.2. Ligand L2
hydrogen bonds but also C–Hꢁ ꢁ ꢁ
p links, define the overall 3D
supramolecular structure observed in the solid state.
Yield: 32%. Anal. Calc. for C12H14N2O (202.2): C, 71.26; H, 6.98;
N, 13.85. Found: C, 71.12; H, 6.85; N, 13.74%. MS(ESI+): m/z
(%) = 225 (47) [L2+Na]+; 203 (100) [L2+H]+. IR (NaCl/cmꢀ1):
m
(O–
(C@N)]ph
m(C@N)]pz 1597, [d(C@C), d(C@N)] 1452, d(C–H)ip
H) 3235,
m(C–H)ar 3038, m(C–H)al 2920, 2874, [m(C@C), m
4. Experimental
1672, [ (C@C),
m
1083, d(C–H)oop 782. 1H NMR (CDCl3 solution, 250 MHz, 298 K)
d = 8.04–7.51 [m, 4H, Hph], 7.42 [d, 1H, 3J 4.7 Hz, Horto ph], 5.96 [s,
1H, CH(pz)], 4.16 [t, 2H, 3J 5.1 Hz, NCH2CH2OH], 3.95 [t, 2H, 3J
5.1 Hz, NCH2CH2OH], 3.91 [br, 1H, NCH2CH2OH], 2.32 [s, 3H,
CH3]. 13C{1H} NMR (CDCl3 solution, 63 MHz, 298 K) d = 152.4 [C–
ph], 138.2 [C–CH3], 131.7 [C–Cph], 129.4–122.6 [Cph], 105.6
[CH(pz)], 61.9 [NpzCH2CH2OH], 50.5 [NpzCH2CH2OH], 13.3 [pz–
CH3].
4.1. General methods
All reactions were performed under a nitrogen atmosphere
using the usual vacuum line and Schlenk techniques. Solvents were
dried and distilled by standard methods and deoxygenated in the
vacuum line before being used. All reagents were commercial
grade and were used without further purification. 1-Phenyl-1,3-
butanedione, [PdCl2(CH3CN)2] and [PtCl2(CH3CN)2] were prepared
as described in the literature [9,13,14].
Elemental analysis (C, N, H) and mass spectra (ESI+-MS) were
carried out by the staff of the Chemical Analysis Services of the
Universitat Autònoma de Barcelona on a Carlo Erba CHNS EA-
1108 instrument and an Esquire 3000 ion trap mass spectrometer
from Bruker Daltonics, respectively. Conductivity measurements
were performed at room temperature in 10ꢀ3 M methanol solu-
tions employing a CiberScan instrument CON 500 conductimeter.
Infrared spectra were recorded on NaCl disks, as KBr pellets or
polyethylene films in the range 4000 to 200 cmꢀ1 under a nitrogen
atmosphere employing a Perkin Elmer FT-2000 spectrophotome-
ter. The 1H and 13C{1H} NMR spectra and bidimensional NMR spec-
tra were run on an NMR-FT Bruker AC-250 spectrometer. All NMR
experiments were recorded on CDCl3 solvent under nitrogen. 1H
and 13C{1H} NMR chemical shifts (d) were determined relative to
internal TMS and are given in ppm. The 195Pt{1H} NMR spectra
were recorded at 298 K in CDCl3 solutions, and 77 Mz on a DPX-
360 MHz Bruker spectrometer using aqueous solutions of [PtCl6]2-
4.3. Synthesis of the complexes [PdCl2(L1)2] (1) and [PdCl2(L2)2] (2)
The appropriate ligand (L1, L2: 0.40 mmol, 0.081 g) dissolved in
dry acetonitrile (25 ml) was added slowly to a solution of [PdCl2(-
CH3CN)2] (0.20 mmol, 0.052 g) in dry acetonitrile (50 ml). The
resulting solution was cooled down to 0 °C and diethyl ether was
then added to induce precipitation. The orange solids were filtered
off, washed twice with 10 ml of diethyl ether and dried under
vacuum.
4.3.1. Complex 1
Yield: 82%. T = 213 °C decomp. Anal. Calc. for C24H28N4O2PdCl2
(581.8): C, 49.60; H, 4.85; N, 9.63. Found: C, 49.37; H, 4.62; N,
9.32%. MS(ESI+): m/z (%) = 546 (100) [PdCl(L1)2]+. Conductivity
(
m
X
ꢀ1 cm2 molꢀ1, 1.08 ꢃ 10ꢀ3 M in methanol): 30. IR (KBr/cmꢀ1):
(O–H) 3309, m(C–H)ar 3117, m(C–H)al 2936, [m(C@C), m(C@N)]
1559, [d(C@C), d(C@N)] 1448, d(C–H)ip 1040, d(C–H)oop 768. (Poly-
ethylene/cmꢀ1): (Pd–Cl) 351. 1H NMR (CDCl3 solu-
m(Pd–N) 487,
m
ꢀ
(0 ppm) as an external reference and delay times 0.01 s.
tion, 250 MHz, 298 K) d isomer anti 8.10 [d, 2H, 3J 7.4 Hz, Horto
ph], 7.60 [s, 8H, Hph], 6.33 [s, 2H, CH(pz)], 5.41 [t, 4H, 3J 6.6 Hz,
NCH2CH2OH], 4.31 [t, 4H, 3J 6.6 Hz, NCH2CH2OH], 3.15 [br, 2H,
NCH2CH2OH], 2.38 [s, 6H, CH3]. d isomer syn 7.89 [d, 2H, 3J
8.1 Hz, Horto ph], 7.16 [s, 8H, Hph], 6.31 [s, 2H, CH(pz)], 4.78 [t, 4H,
3J 5.7 Hz, NCH2CH2OH], 4.01 [t, 4H, 3J 5.7 Hz, NCH2CH2OH], 3.14–
2.84 [br, 2H, NCH2CH2OH], 2.35 [s, 6H, CH3]. 13C{1H} NMR (CDCl3
solution, 63 MHz, 298 K) d isomer anti 149.2 [C–ph], 140.3 [C–
CH3], 133.8 [C–Cph], 129.8–128.5 [Cph], 108.1 [CH(pz)], 60.3 [Npz-
CH2CH2OH], 51.4 [NpzCH2CH2OH], 12.3 [pz–CH3]. d isomer syn
149.0 [C–ph], 139.9 [C–CH3], 133.6 [C–Cph], 129.8–128.5 [Cph],
108.4 [CH(pz)], 60.1 [NpzCH2CH2OH], 51.7 [NpzCH2CH2OH], 12.6
[pz–CH3].
4.2. Synthesis of 2-(5-methyl-3-phenyl-1H-pyrazol-1-yl)ethanol (L1)
and 2-(3-methyl-5-phenyl-1H-pyrazol-1-yl)ethanol (L2)
1-Phenyl-1,3-butanedione (1.2 mmol, 0.19 g) was dissolved in
absolute ethanol (25 ml). To this solution 2-hydroxyethylhydra-
zine (1.3 mmol, 0.10 g) was added and the mixture was stirred at
room temperature for 16 h. After removing the solvent under vac-
uum, the product was extracted from the oil residuum with H2O/
CHCl3. The collected organic phases were dried with anhydrous
calcium sulphate and removed under vacuum. Ligands were ob-
tained in 98% yield as oils with sufficient purity (1H NMR). The sep-
aration of regioisomers was done by silica column chromatography
using ethyl acetate as eluent.
4.3.2. Complex 2
In the case of the synthesis at low temperature, the same proce-
dure was followed. Reaction was performed during the same time
but at -84 °C using a cooling mixture of ethyl acetate/liquid N2.
Yield: 75%. T = 227 °C decomp. Anal. Calc. for C24H28N4O2PdCl2
(581.8): C, 49.60; H, 4.85; N, 9.63. Found: C, 49.57; H, 4.65; N,
9.35%. MS(ESI+): m/z (%) = 546 (100) [PdCl(L2)2]+. Conductivity

28
J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
(
m
X
ꢀ1 cm2 molꢀ1, 1.15 ꢃ 10ꢀ3 M in methanol): 19. IR (KBr/cmꢀ1):
4H, 3J 5.7 Hz, NCH2CH2OH], 2.84 [s, 6H, CH3]. 13C{1H} NMR (CDCl3
(O–H) 3398,
m
(C–H)ar 3045,
m
(C–H)al 2938, [
m
(C@C),
m
(C@N)]
solution, 63 MHz, 298 K) d isomer anti 153.1 [C–ph], 143.5 [C–
CH3], 137.2 [C–Cph], 131.4–128.7 [Cph], 108.9 [CH(pz)], 62.4 [Npz-
CH2CH2OH], 52.7 [NpzCH2CH2OH], 15.9 [pz–CH3]. 195Pt{1H} NMR
(CDCl3 solution, 77 MHz, 298 K) d isomer anti ꢀ2189 ppm.
1555, [d(C@C), d(C@N)] 1500, d(C–H)ip 1014, d(C–H)oop 772. (Poly-
ethylene/cmꢀ1): (Pd–Cl) 355. 1H NMR (CDCl3 solu-
m(Pd–N) 494,
m
tion, 250 MHz, 298 K) d isomer anti 7.47 [s, 10H, Hph], 6.19 [s, 2H,
CH(pz)], 4.97 [t, 4H, 3J 6.4 Hz, NCH2CH2OH], 4.22 [t, 4H, 3J 6.4 Hz,
NCH2CH2OH], 3.03 [s, 6H, CH3], 2.62 [br, 2H, NCH2CH2OH]. d isomer
syn 7.35 [s, 10H, Hph], 6.17 [s, 2H, CH(pz)], 4.75 [t, 4H, 3J 5.8 Hz,
NCH2CH2OH], 3.88 [t, 4H, 3J 5.8 Hz, NCH2CH2OH], 2.95 [s, 6H,
CH3], 2.64–2.62 [br, 2H, NCH2CH2OH]. 13C{1H} NMR (CDCl3 solu-
tion, 63 MHz, 298 K) d isomer anti 150.2 [C–ph], 141.7 [C–CH3],
134.2 [C–Cph], 130.1–129.3 [Cph], 109.1 [CH(pz)], 62.0 [NpzCH2-
CH2OH], 52.5 [NpzCH2CH2OH], 15.7 [pz–CH3]. d isomer syn 149.8
[C–ph], 141.9 [C–CH3], 133.8 [C–Cph], 130.1–129.3 [Cph], 108.9
[CH(pz)], 61.3 [NpzCH2CH2OH], 52.2 [NpzCH2CH2OH], 15.6 [pz-CH3].
4.4.2. Complex 4
Yield: 62%. T = 248 °C decomp. Anal. Calc. for C24H28N4O2PtCl2
(670.5): C, 43.05; H, 4.21; N, 8.36. Found: C, 42.88; H, 4.32; N,
8.39%. MS(ESI+): m/z (%) = 635 (100) [PtCl(L1)2]+. Conductivity
(
m
X
ꢀ1 cm2 molꢀ1, 9.20 ꢃ 10ꢀ4 M in methanol): 26. IR (KBr/cmꢀ1):
(O–H) 3448, m(C–H)ar 3052, m(C–H)al 2970, 2919, [m(C@C),
m
(C@N)] 1559, [d(C@C), d(C@N)] 1449, d(C-H)ip 1029, d(C–H)oop
803. (Polyethylene/cmꢀ1):
m
(Pt–N) 462,
m
(Pt–Cl) 348. 1H NMR
(CDCl3 solution, 250 MHz, 298 K) d isomer anti 7.58 [s, 10H, Hph],
6.14 [s, 2H, CH(pz)], 5.41 [t, 4H, 3J 6.6 Hz, NCH2CH2OH], 4.02 [t,
4H, 3J 6.3 Hz, NCH2CH2OH], 2.35 [s, 6H, CH3]. 13C{1H} NMR (CDCl3
solution, 63 MHz, 298 K) d isomer anti 152.4 [C–ph], 142.7 [C–
CH3], 135.6 [C-Cph], 129.8–128.5 [Cph], 108.0 [CH(pz)], 60.2 [Npz-
CH2CH2OH], 51.4 [NpzCH2CH2OH], 12.3 [pz–CH3]. 195Pt{1H} NMR
(CDCl3 solution, 77 MHz, 298 K) d isomer anti ꢀ2152 ppm.
4.4. Synthesis of the complexes [PtCl2(L1)2] (3) and [PtCl2(L2)2] (4)
The appropriate ligand ((L1, L2: 0.25 mmol, 0.051 g) dissolved
in dry acetonitrile (25 ml) was added slowly to a solution of
[PtCl2(CH3CN)2] (0.13 mmol, 0.045 g) in dry acetonitrile (50 ml).
The resulting solution was stirred and refluxed for 24 h and con-
centrated on a vacuum line to one fifth of the initial volume. The
yellow solids were filtered off, washed twice with 5 ml of diethyl
ether and dried under vacuum.
4.5. X-ray crystal structures for compounds L2 ligand, trans-
[PdCl2(L1)2] (1) and trans-[PdCl2(L2)2] (2)
Suitable crystals for X-ray diffraction of L2 ligand were obtained
through crystallisation from ethyl acetate solution, and for com-
pounds, trans-[PdCl2(L1)2] (1) and trans-[PdCl2(L2)2] (2) were ob-
tained through crystallisation from a chloroform solution.
For compounds L2, 1 and 2, a prismatic crystal was selected and
mounted on a MAR345 diffractometer, with an image plate detec-
tor for L2 and 1, and on an Enraf–Nonius CAD4, four-circle diffrac-
tometer for 2.
4.4.1. Complex 3
Yield: 68%. T = 236 °C decomp. Anal. Calc. for C24H28N4O2PtCl2
(670.5): C, 43.05; H, 4.21; N, 8.36. Found: C, 42.81; H, 4.07; N,
8.43%. MS(ESI+): m/z (%) = 635 (100) [PtCl(L1)2]+. Conductivity
(
m
X
ꢀ1 cm2 molꢀ1, 1.09 ꢃ 10ꢀ3 M in methanol): 18. IR (KBr/cmꢀ1):
(O–H) 3435, m(C–H)ar 3028, m(C–H)al 2968, 2931, [m(C@C),
m
(C@N)] 1554, [d(C@C), d(C@N)] 1437, d(C–H)ip 1032, d(C–H)oop
812. (Polyethylene/cmꢀ1):
m(Pt–N) 458,
m
(Pt–Cl) 344. 1H NMR
For L2, unit-cell parameters were determined from 456 reflec-
(CDCl3 solution, 250 MHz, 298 K) d isomer anti 7.21 [s, 10H, Hph],
tions (3° < h < 31°) and refined by least-squares method. Intensities
6.03 [s, 2H, CH(pz)], 4.91, [t, 4H, 3J 5.9 Hz, NCH2CH2OH], 3.96 [t,
were collected with graphite monochromatized Mo K
a radiation.
Table 6
Crystallographic data for L2, 1 and 2.
L2
1
2
Formula
Molecular weight
T (K)
Crystal System
Space group
Unit cell dimensions
a (Å)
C
12H14N2O
C24H28Cl2N4O2Pd
581.80
293(2)
tetragonal
I41/a
C24H28Cl2N4O2Pd
581.80
293(2)
triclinic
Pbar1
202.25
293(2)
triclinic
Pbar1
10.289(7)
11.777(9)
20.067(4)
86.11(3)
89.46(2)
64.57(2)
8
2190(2)
1.227
0.080
22.7902(12)
22.7902(12)
19.2949(7)
90
90
90
11.100(6)
11.611(3)
12.210(4)
106.82(3)
100.06(4)
116.36(4)
2
1262.6(12)
1.530
0.975
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Z
16
V (Å3)
10021.6(8)
1.542
0.982
Dcalc (g cmꢀ3
)
l
(mmꢀ1
)
F(000)
864
4736
592
Crystal size (mm)
h range (°)
0.19 ꢃ 0.18 ꢃ 0.17
0.2 ꢃ 0.1 ꢃ 0.1
0.09 ꢃ 0.08 ꢃ 0.07
1.92–25.03
1.38–24.92
2.12–29.97
Index range
ꢀ11 6 h 6 12, ꢀ11 6 k 6 11, 0 6 l 6 23 ꢀ19 6 h 6 18, 0 6 k 6 27, 0 6 l 6 22 ꢀ15 6 h 6 15, ꢀ16 6 k 6 15, 0 6 l 6 17
Reflections collected/unique
Completeness to h (%)
Absorption correction
Maximum and minimum transmissions
Data/restraints/parameters
Goodness-of-fit
8145/5034 [Rint = 0.0352]
65.3
27967/4372 [Rint = 0.0518]
85.5
7327/7276 [Rint = 0.0209]
100.0
empirical
empirical
none
0.99 and 0.98
5034/8/542
1.050
0.91 and 0.89
3756/2/305
1.151
–
7326/3/303
1.009
Final R1,
R1 (all data),
Largest difference in peak and hole (e Åꢀ3
x
R2
0.0468, 0.1447
0.0720, 0.1518
0.127 and ꢀ0.155
0.0537, 0.1309
0.0816, 0.1470
0.428 and ꢀ0.846
0.0644, 0.1329
0.1595, 0.1589
1.255 and ꢀ0.462
xR2
)

J.A. Perez et al. / Inorganica Chimica Acta 394 (2013) 21–30
29
(g) C.-K. Koo, Y.-M. Ho, C.-F. Chow, M.H.-W. Lam, T.-C. Lau, W.-Y. Wong, Inorg.
Chem. 46 (2007) 3603;
(h) C.-K. Koo, B. Lam, S.-K. Leung, M.H.-W. Lam, W.-Y. Wong, J. Am. Chem. Soc.
128 (2006) 16434;
8145 reflections were measured in the range 1.92° 6 h 6 25.03°.
5034 of which were non-equivalent by symmetry (Rint(on
I) = 0.035). 3092 reflections were assumed as observed applying
(i) A.S. Lokin, W.J. Marshall, Y. Wang, Organometallics 24 (2005) 619.
[2] (a) J. Pons, J. Ros, M. Llagostera, J.A. Pérez, M. Ferrer, Spanish Patent No. 01494,
2003.;
the conditions I > 2r(I).
For 1, unit-cell parameters were determined from automatic cen-
tring of 221 reflections (3° < h < 31°) and refined by least-squares
method. Intensities were collected with graphite monochromatized
(b) R.W.-Y. Sun, D.L. Ma, E.L.-M. Wong, C.M. Che, Dalton (2007) 4883;
(c) A. Satake, T. Nakata, J. Am. Chem. Soc. 120 (1998) 10391;
(d) C. Navarro-Ranninger, L. López-Solera, V.M. González, J.M. Pérez, A.
Alvarez-Valdes, A. Martin, P.R. Raithby, J.R. Massaguer, C. Alonso, Inorg.
Chem. 35 (1996) 5181;
Mo Ka radiation. 27967 reflections were measured in the range
1.38° 6 h 6 24.92°. 4372 of which were non-equivalent by symme-
try (Rint(on I) = 0.051). 3740 reflections were assumed as observed
applying the conditions I > 2r(I).
For 2, unit-cell parameters were determined from automatic
centring of 25 reflections (12° < h < 21°) and refined by least-
squares method. Intensities were collected with graphite mono-
(e) C. Navarro-Ranninger, L. López-Solera, J.M. Pérez, J.R. Massaguer, C. Alonso,
Appl. Organomet. Chem. 7 (1993) 57;
(f) J.D. Higgins, L. Neely, S. Fricker, J. Inorg. Biochem. 49 (1993) 149.
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Ros, Inorg. Chem. 47 (2008) 11084;
(b) J.M. Lehn, Science 260 (1993) 1762;
(c) C.A. Mirkin, M.A. Ratner, Annu. Rev. Phys. Chem. 43 (1992) 719;
(d) C. López, A. Caubet, S. Pérez, X. Solans, M. Font-Bardía, J. Organomet. Chem.
681 (2003) 82.
chromatized Mo Ka radiation, using x/2h scan-technique. 7327
reflections were measured in the range 2.12° 6 h 6 29.97°. 7276
of which were non-equivalent by symmetry (Rint(on I) = 0.020).
3801 reflections were assumed as observed applying the condition
I > 2r(I). Three reflections were measured every two hours as ori-
entation and intensity control, significant intensity decay was not
[4] (a) V. Montoya, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía, J. Ros,
Organometallics 26 (2007) 3183;
(b) M. Guerrero, J. Pons, J. Ros, J. Organomet. Chem. 695 (2010) 1957;
(c) J. Dupont, M. Pfeffer, J. Spencer, Eur. J. Inorg. Chem. (2001) 1917;
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observed.
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(2005) 2312;
For L2, 1 and 2, Lorentz-polarisation but no absorption correc-
tions were made.
(b) A. Boixassa, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 357
(2004) 733;
(c) A. Boixassa, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 346
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All structures, were solved by Direct methods, using SHELXS com-
puter program (SHELXS-97) [26] and refined by full matrix least-
squares method with SHELXL-97 [27] computer program using
8145 reflections for L2, 298 reflections for 1 and 7327 reflections
for 2 (very negative intensities were not assumed).
For L2, the function minimised was
R
w||FO|2 ꢀ |FC|2|2, where
[6] (a) Cambridge Structural Database, version 5.33, Cambridge Crystal Data
Centre, Cambridge, UK, 2012.;
(b) F.A. Allen, Acta Crystallogr., Sect. B 58 (2002) 380.
[7] (a) G. Aragay, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-Bardía,
J. Ros, Aust. J. Chem. 63 (2010) 257;
w = [
tion minimised was
r
2(I) + (0.0899P)2]ꢀ1, and P = (|FO|2 + 2|FC|2)/3. For 1, the func-
R
w||FO|2 ꢀ |FC|2|2, where w = [
r
2(I)
+ (0.1011)P2 + 36.974P]ꢀ1, and P = (|FO|2 + 2|FC|2)/3. For 2, the func-
(b) M. Guerrero, J. Pons, T. Parells, M. Font-Bardía, T. Calvet, J. Ros, Inorg. Chem.
48 (2009) 8736;
(c) A. Boixassa, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 355
(2003) 254.
tion minimised was
R
w||FO|2 ꢀ |FC|2|2, where w = [
r
2(I)
+ (0.0083P)2]ꢀ1 and P = (|FO|2 + 2|FC|2)/3.
For L2, 1 and 2, all hydrogen atoms are computed and refined,
using a riding model, with an isotropic temperature factor equal
to 1.2 times the equivalent temperature factor of the atom which
is linked. The final R(F) factor and RW(F2) values as well as the num-
ber of parameters refined and other details concerning the refine-
ment of the crystal structures are gathered in Table 6.
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Acknowledgement
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Organometallics 26 (2007) 3183.
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Support by the Spanish Ministerio de Educación y Cultura (Pro-
jects CTQ-2007-63913BQU and MAT2011-27225) gratefully
acknowledged.
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Appendix A. Supplementary material
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CCDC 872758, 872759 and 872760 contain the supplementary
crystallographic data for compounds L2, 1 and 2, respectively.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
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