Pd(ii) and Pt(ii) coordination chemistry with hybrid pyridine-pyrazole ligands: From 3D-frameworks structures in molecular complexes

Article abstract of DOI:10.1071/CH13021

In this paper we studied the reaction of ligands 2-[5-phenyl-1-(3,6,9- trioxodecane)-1H-pyrazol-3-yl]pyridine (L1) and 3,5-bis(2-pyridyl)-1-(3,6,9- trioxodecane)-1H-pyrazole (L2) with [MCl2(CH3CN)2] (M≤Pd(ii), Pt(ii)), to obtain monomeric complexes [MCl2(L)] (M≤Pd(ii):L≤L1 (1), L≤L2 (2); M≤Pt(ii):L≤L1 (3), L≤L2 (4)). Additionally, the reaction of [Pd(CH ₃COO)₂] with L1 (5) and L2 (6) was also studied pointing out dimeric structures with bridged acetates between the Pd(ii) atoms. All complexes were characterised by elemental analyses, conductivity measurements, infrared spectroscopy (IR), ¹H, ¹³C{¹H}, and ¹⁹⁵Pt{1H} NMR spectroscopies, and electrospray ionisation mass spectrometry (MS-ESI(+)). The crystal structure of complex [PtCl ₂(L1)] (3) was determined by X-ray diffraction methods; it consists of a mononuclear complex where L1 acts as a bidentate chelate ligand. Moreover, we also studied the extended structure observing that the ether, present in the alkyl chain of the ligand, chlorine, and platinum moieties play a fundamental role in the final disposition of the supramolecular structure. All these results show how the design of an appropriate hybrid ligand can strongly influence the structural control of the molecular packing.

Full text of DOI:10.1071/CH13021

CSIRO PUBLISHING
Aust. J. Chem. 2013, 66, 685–691
Full Paper
http://dx.doi.org/10.1071/CH13021
Pd(II) and Pt(II) Coordination Chemistry with Hybrid
Pyridine-Pyrazole Ligands: from 3D-Frameworks
Structures in Molecular Complexes
A
A
B
C
Miguel Guerrero, Jose´ A. Pe´rez, Teresa Calvet, Merce` Font-Bard´ıa,
A D
,
and Josefina Pons
A
Departament de Qu´ımica, Unitat de Qu´ımica Inorga`nica, Universitat Auto`noma de
Barcelona, 08193-Bellaterra, Barcelona, Spain.
B
Cristalꢀlografia, Mineralogia i Dipo`sits Minerals, Universitat de Barcelona,
Mart´ı i Franque`s s/n, 08028-Barcelona, Spain.
C
Unitat de Difraccio´ de RX. Centres Cient´ıfics i Tecnolo`gics de la Universitat de
Barcelona (CCiTUB), Universitat de Barcelona, Sole´ i Sabar´ıs 1-3,
08028-Barcelona, Spain.
D
Corresponding author. Email: Josefina.Pons@uab.es
In this paper we studied the reaction of ligands 2-[5-phenyl-1-(3,6,9-trioxodecane)-1H-pyrazol-3-yl]pyridine (L1) and
3,5-bis(2-pyridyl)-1-(3,6,9-trioxodecane)-1H-pyrazole (L2) with [MCl2(CH3CN)2] (M ¼ Pd(II), Pt(II)), to obtain mono-
meric complexes [MCl2(L)] (M ¼ Pd(II): L ¼ L1 (1), L ¼ L2 (2); M ¼ Pt(II): L ¼ L1 (3), L ¼ L2 (4)). Additionally, the
reaction of [Pd(CH3COO)2] with L1 (5) and L2 (6) was also studied pointing out dimeric structures with bridged acetates
between the Pd(II) atoms. All complexes were characterised by elemental analyses, conductivity measurements, infrared
1
spectroscopy (IR), H, 13C{1H}, and 195Pt{1H} NMR spectroscopies, and electrospray ionisation mass spectrometry
(MS-ESI(þ)). The crystal structure of complex [PtCl2(L1)] (3) was determined by X-ray diffraction methods; it consists of
a mononuclear complex where L1 acts as a bidentate chelate ligand. Moreover, we also studied the extended structure
observing that the ether, present in the alkyl chain of the ligand, chlorine, and platinum moieties play a fundamental role in
the final disposition of the supramolecular structure. All these results show how the design of an appropriate hybrid ligand
can strongly influence the structural control of the molecular packing.
Manuscript received: 13 January 2013.
Manuscript accepted: 22 March 2013.
Published online: 13 June 2013.
Introduction
and have been used in liquid crystals, self-assembled species,
and catalysis,[10,11] are considered excellent candidates to build
1D, 2D, and 3D frameworks due to their steric profile being
highly dependent on the presence of substituents, their size, and
their position on the aromatic ring.[12]
During the past 20 years thesmart design of new multi-functional
composites[1] with appealing properties have been of great
interest and have been actively pursued in fields like materials
chemistry, crystal engineering, or biomedicine.[2–5] One of the
most important issues in this field is to achieve the correct
molecular packing through the smart design of all the elements
involved, which, in turn, will affectthe macroscopicproperties of
the material. Moreover, non-covalent interactions like hydrogen
bonding are a particularly powerful building motif for the con-
struction of self-assembling supramolecular structures.[6–8]
In the process of self-assembly of metallic complexes there
are two main issues to take into account: a) the number and type
of coordinating moieties which contains the used ligand in the
reaction, and b) the coordination number and the preferred
geometry of the chosen metallic centre. Regarding the ligand,
heterocycles represent an intelligent option because of their ring
structure containing heteroatoms with different coordination
behaviour; this fact has been clearly proved in the past century
with wide application in all areas of coordination chemistry, for
example, of azole-derived ligands.[9] Moreover, pyrazole
ligands, which are able to be engaged in hydrogen bonding
We have previously described the synthesis, characterisa-
tion, and reactivity towards Pd(II) of several families of hybrid
3,5-dimethylpyrazole ligands containing N-polyetheralkyl
chains,[13,14] with phenyl groups in different relative posi-
tions,[15,16] as well as using the mixed-donor ligand 1,8-
bis(3,5-dimethyl-1H-pyrazol-1yl)-3,6-dioxaoctane.[17] A high
versatility of these ligands has been observed and their denticity
varies from N,N-bidentate (chelate or bridge) to N,O,O,N-
tetradentate (equatorial or axial).[17] Furthermore, these hybrid
pyrazole ligands have also been found to accommodate a range
of metal coordination geometries (tetrahedral, cis/trans-square
planar, or octahedral) and nuclearity (monomer, dimer, or
polymer), as a consequence of the coordination requirement
of the metals, the reaction conditions, and the variety of the
donor atoms.[18,19]
As an extension of the above results, we have recently
described the synthesis and characterisation of a new family
Journal compilation Ó CSIRO 2013
www.publish.csiro.au/journals/ajc

686
M. Guerrero et al.
(a)
(b)
N
N
N
N
N
O
N
N
O
O
O
O
O
L2
L1
M ꢀ Pd, L ꢀ L1 (1)
M ꢀ Pd, L ꢀ L2 (2)
[MCl2(CH3CN)2]
[M(CH3COO)2]
[MCl2(L)]
M ꢀ Pt, L ꢀ L1 (3)
M ꢀ Pt, L ꢀ L2 (4)
L1 or L2
M ꢀ Pd, L ꢀ L1 (5)
M ꢀ Pd, L ꢀ L2 (6)
[M2(CH3COO)4(L)2]
Scheme 1.
C21
C20
O3
C19
C2
C3
C5
O2
C1
N1
Cl1
C4
C18
Pt
C17
O1
C6
N2
C7
C16
Cl2
N3
C8
C10
C15
C9
C11
C12
C14
C13
Fig. 1. ORTEP diagram of complex cis-[PtCl2(L1)] (3) showing all non-hydrogen atoms and the atom-numbering
scheme; 50 % probability displacement ellipsoids are shown.
of N-polyetherpyrazole ligands introducing pyridine substitu-
ents: 2-[5-phenyl-1-(3,6,9-trioxodecane)-1H-pyrazol-3-yl]
[MCl2(CH3CN)2] (M ¼ Pd(II), Pt(II)) was reacted with the
corresponding pyrazole ligand (L1, L2) using 1M : 1 L ratio
in an acetonitrile solution (Scheme 1). The ability of L1 and
L2 to coordinate Pd(II) and Pt(II) metallic centres is com-
parable to other complexes with N-alkylpyrazole,[20–22] and
N-hydroxyalkylpyrazole [23–25] ligands.
The elemental analyses are consistent with the formula
[MCl2(L)] (M ¼ Pd(II), Pt(II)) for compounds 1–4. The positive
ionisation mass spectra (ESI(þ)-MS) of compounds 1–4 give
peaks with m/z values of 509 (100 %) (1), 510 (100 %) (2), 598
(100 %) (3), and 599 (100 %) (4); all of them are attributable to
[M-Cl]þ (M ¼ Pd(II), Pt(II)). Molecular peaks are observed with
the same isotope distribution as the theoretical ones. Complexes
1–4 are slightly soluble in common organic solvents, such as
pyridine (L1) and 3,5-bis(2-pyridyl)-1-(3,6,9-trioxodecane)-
1H-pyrazole (L2) (M. Guerrero, J. A. Pe´rez, V. Branchadell,
et al., unpubl. data). Due to their potential application in
supramolecular chemistry, here we present a study of the
synthesis and characterisation of new Pd(II) and Pt(II) complexes
with these hybrid pyridine-pyrazole ligands, and compare with
closely related complexes.
Results and Discussion
Synthesis and Spectroscopic Properties of Complexes 1–4
Complexes cis-[MCl2(L)] (M ¼ Pd(II): L ¼ L1 (1), L2 (2);
M ¼ Pt(II): L ¼ L1 (3), L2 (4)) were obtained when

Effect of Hybrid Ligand in Supramolecular Chemistry
687
˚
Table 1. Selected bond lengths [A] and bond angles [8] for
cis-[PtCl2(L1)] (3)
Table 2. Crystallographic data for cis-[PtCl2(L1)] (3)
cis-[PtCl2(L1)] (3)
˚
Bond length [A]
Molecular formula
C21H25Cl2N3O3Pt
633.43
Pt-N(1)
2.040(9)
2.050(9)
Pt-Cl(1)
Pt-Cl(2)
2.298(3)
2.307(3)
Formula weigh
Pt-N(2)
Temperature (K)
˚
Wavelength (A)
293(2)
Bond angles [8]
N(1)-Pt-N(2)
Cl(1)-Pt-Cl(2)
N(1)-Pt-Cl(1)
0.71069
78.6(4)
N(1)-Pt-Cl(2)
N(2)-Pt-Cl(1)
N(2)-Pt-Cl(2)
179.1(3)
System, space group
Unit cell dimensions
˚
a (A)
˚
b (A)
˚
c (A)
Monoclinicic, P21/c
87.08(14)
93.7(3)
172.2(2)
100.6(3)
9.093(11)
17.669(6)
16.537(4)
117.65(4)
2353(3)
4
b (8)
3
˚
V (A )
acetone, dichloromethane, or ethanol. Thus, dimethyl sulfoxide
was used for the conductivity measurements. The obtained
values (22–36 Oꢁ1 cm2 molꢁ1) show the non-ionic behaviour
of 1–4 (conductivity values for a non-electrolyte are below
50 Oꢁ1 cm2 molꢁ1 in DMSO solution).[26,27] The IR spectra
studied in the range of 4000–400 cmꢁ1 show the coordination
of the ligands to the Pd(II) or Pt(II) atom (Fig. S1, Crystallo-
graphic data). The (n(C¼C), n(C¼N))ar (ar ¼ aromatic) bands
of the pyrazole ligand increase in frequency when part of the
complex, whereas no significant change is observed in the
n(C-O-C)as (as ¼ asymmetric) band.[28,29]
Z
Dcalc (g cmꢁ3
)
1.788
m (mmꢁ1
F(000)
)
6.215
1232
Crystal size (mm3)
0.2 ꢂ 0.1 ꢂ 0.1
hkl ranges
ꢁ12 # h # 12–24 # k # 6,ꢁ12 # l # 23
2.31 to 29.98
2 y Range (8)
Reflections collected/
7089/6813[R(int) ¼ 0.0560]
unique/[Rint
]
Completeness to y
99.4
Absorption correction
Data/restrains/parameters
Goodness-of-fit on F2
Final R indices [I .2 s (I)]
R indices (all data)
None
The IR spectra of complexes 1–4 in the 600–100 cmꢁ1 region
were also studied. The presence of bands between 492–
462 cmꢁ1 for Pd(II) and 483–450 cmꢁ1 for Pt(II) complexes,
assigned to n(M-N), confirm the coordination of the Npz (pz ¼
pyrazole) of the ligand to the metallic atom. It is remarkable to
point out that both palladium and platinum complexes display
two n(M-Cl) bands between 356 and 331 cmꢁ1, indicating that
the chlorine atoms are coordinated to the M(II) atom in cis
disposition,[30] due to the chelating structure of the ligand.
1H, 13C{1H}, and HSQC NMR spectra for complexes 1–4 in
CDCl3 show the signals of the coordinated ligands.[28,29] All
NMR signals are reported in detail in the Experimental section.
In the 1H NMR spectra, characteristic signals for the CH(pz) are
observed between 7.00 and 6.73 ppm. The protons of the
3,6,9-trioxodecane chain appear between 5.59 and 3.31 ppm,
and the protons of the methyl group of the chain between 3.41
and 3.32 ppm.
6813/5/242
0.986
R1 ¼ 0.0722, wR2 ¼ 0.1168
R1 ¼ 0.2289, wR2 ¼ 0.1496
1.323 and ꢁ1.244
Largest diff. peaꢁk3
˚
and hole (e A
)
parameters and details concerning the refinement of the crystal
structures are gathered in Table 2.
The platinum centre has typical square-planar geometry
(with a slight tetrahedral distortion) showing the largest devia-
˚
tion from the mean coordination plane (0.014 A). The metal
atom is coordinated to one L1 ligand via one pyrazole nitrogen,
one pyridine nitrogen, and two chlorine atoms in a cis-disposition.
The L1 ligand behaves as a chelated bidentate ligand (bite angle
of 78.6(4)8) forming a five-membered metallocycle.
˚
In the 13C{1H} NMR spectra the signals attributable to
CH(pz) appear between 108.4 and 104.6 ppm, the carbons of
the 3,6,9-trioxodecane chain between 71.8 and 49.3 ppm, and
the carbon of the methyl group of the chain between 59.9 and
58.8 ppm. Interestingly, when the ligand is part of the complex
the signals of CH(pz) in the H NMR decrease in chemical
shift, while the signals increase in chemical shift in the
13C{1H} NMR.
Additionally, 195Pt{1H} NMR experiments for complexes 3
and 4, at 298 K, have been also recorded in CDCl3 and display
only one signal for each complex at d ¼ ꢁ2187 ppm (3) and
ꢁ2173 ppm (4). These values appear in the range described in
the literature for complexes with [PtCl2N2] core (between
ꢁ2447 and ꢁ1198 ppm).[30–32] These data illustrate how sensi-
tive the platinum chemical shift is to the average ligand
environment.
The bond distances Pt-Npy (2.040(9) A, where py ¼ pyridine)
˚
are in the same order as Pt-Npz (2.050(9) A). The Pt-Npy, Pt-Npz,
and Pt-Cl distances are in the usual range found for other
platinum complexes containing analogous ligands.[33] The
[PtCl2(Npy)(Npz)] core (containing pyrazole, pyridine nitrogen
atoms, and terminal chlorine atoms) is found in seven complexes
describes in the literature.[22,34–36] It is important to mention that
L1 is not positioned in a planar way; pyridyl and phenyl groups
of the ligands are clearly twisted with respect to the pyrazole
ring. Whereas the pyridyl group is slightly twisted (py-pz
dihedral angle 4.18), the phenyl group (ph) shows a significant
torsion with respect to pyrazole (ph-pz dihedral angle 55.68).
The 3,6,9-trioxodecane group, which is bonded to N(3), moves
away from the chelating plane giving a torsion angle
(N(2)-N(3)-C(15)-C(16)) of ꢁ74.08; this value is lower than
others previously reported ([PdCl2(LA)] (LA ¼ 1-octyl-3,5-bis
(2-pyridyl)pyrazole).[22]
1
Crystal and Molecular Structure of Complex
cis-[PtCl2(L1)] (3)
Extended Structure of cis-[PtCl2(L1)] (3)
The crystal structure of 3 consists of discrete cis-[PtCl2(L1)]
molecules linked by intermolecular forces (Fig. 1). Selected
bond distances and angles are given in Table 1 and other
In order to shed light on the final disposition of the self-
assembled structure it is necessary to study the interactions
between the metal centres and the organic ligands. In this case,

688
M. Guerrero et al.
H19
3.403 Å
2.697 Å
2.618 Å
Fig. 2. A view of the three-dimensional layered supramolecular architecture of cis-[PtCl2(L1)] (3) along the [100]
direction, generated by C-HꢃꢃꢃCl (blue) and C-HꢃꢃꢃO (red) intermolecular interactions.
˚
the extended structure analyses revealed a novel three-
dimensional network (Fig. 2). What is more important, the
presence of intermolecular hydrogen bonds (C-HꢃꢃꢃCl) have
been studied in recent times. These kind of interactions have
proved to be key for the final configuration of the supra-
molecular structure of solids.[37–39] So, we have investigated the
self-assembly pattern of complex [PtCl2(L1)] (3) in the crystal
structure mainly through different intermolecular hydrogen
bonding interactions (C-HꢃꢃꢃCl and C-HꢃꢃꢃO) and also inter-
metallic interactions (PtꢃꢃꢃPt). All the bonding parameters are
gathered in Table 3.
Table 3. Distances [A] and angles [deg] related to hydrogen bonding
in complex 3
Symmetry codes: (i) ꢁ1 þ x, y, z; (ii) ꢁ1 þ x, 1/2 ꢁ y, ꢁ1/2 þ z; (iii) ꢁ1 þ x,
y, ꢁ1 þ z; (iv) 1 þ x, y, 1 þ z; (v) 1 ꢁ x, ꢁy, ꢁz; (vi) 1 ꢁ x, ꢁy, ꢁz
D-H
DꢃꢃꢃA
AꢃꢃꢃH
D-HꢃꢃꢃA
C(7)–H(7)ꢃꢃꢃCl(2)i
0.93
0.97
0.96
0.93
0.93
0.97
3.64(1)
3.76(2)
3.73(2)
3.33(1)
3.43(2)
3.60(2)
2.72
2.94
2.94
2.54
2.62
2.70
170
142
140
143
146
156
C(19)–H(19)ꢃꢃꢃCl(1)ii
C(21)–H(21)ꢃꢃꢃCl(1)iii
C(1)–H(1)ꢃꢃꢃO(3)iv
C(14)–H(14)ꢃꢃꢃO(3)v
C(15)–H(15A)ꢃꢃꢃO(2)vi
Three different H atoms (H7, H19, and H21) (Fig. 2) are
engaged in hydrogen bonds with the Cl atom, which acts as the
sole receptor for the interactions. Each [PtCl2(L1)] unit is linked
to seven neighbouring molecules, via C-HꢃꢃꢃCl hydrogen bond-
interdigitation. This fact confirms that the oxygen atoms,
present in the alkyl chain of L1, play an important role in the
generation of these directional hydrogen bonding interactions.
All the C-HꢃꢃꢃX (X ¼ Cl or O) intermolecular contacts can be
considered as ‘weak’ on the basis of the contact distances and
angles.[40] Moreover, important intermetallic interactions
˚
ing (bond distances and angles ranging between 2.72–2.94 A
and 140–1708, respectively), accompanied by cooperative
C-HꢃꢃꢃO interactions (bond distances and angles ranging
˚
between 2.54–2.704 A and 143–1568, respectively), forming
layers of molecules with opposite distributions showing clear

Effect of Hybrid Ligand in Supramolecular Chemistry
689
˚
(3.403(1)A) have also been observed between adjacent Pt
atoms (Fig. 2).
between the Pd(II) atoms. All new complexes have been char-
acterised by elemental analyses, conductivity measurements,
infrared and 1H, 13C{1H}, and 195Pt{1H} NMR spectroscopies,
and MS-ESI(þ) spectrometry.
Synthesis and Spectroscopic Properties
of Complexes 5 and 6
The crystal structure of complex [PtCl2(L1)] (3) was deter-
mined by X-ray diffraction methods showing a square planar
geometry unit where the platinum centre is coordinated to one
bidentate L1 ligand and two chlorine atoms in cis disposition.
The extended structure shows that the ether moieties, present in
the alkyl chain of the ligand, as well as Cl and Pt atoms, play a
fundamental role in the final disposition in the supramolecular
structure. All these results show how the design of an appropri-
ate hybrid ligand can strongly influence structural control of
molecular packing.
To study the effect of the anion, we have also studied the
reaction of L1 and L2 with [Pd(Ac)2] (Ac ¼ CH3COOꢁ), giving
rise to dimeric complexes [Pd(Ac)(L)]2(Ac)2 (L ¼ L1 (5) and L2
(6)). In contrast to complexes 1–4, complexes 5 and 6 are soluble
in acetone, dichloromethane, and ethanol. The proposed
formula was confirmed by elemental analyses. The positive
ionisation mass spectra (MS-ESI(þ)), of complexes 5 and 6,
give peaks with m/z values of 529 (100 %) (5) and 530 (100 %)
(6), attributable to [Pd(Ac)(L)]þ. Molecular peaks of the cations
and the theoretical ones are observed with the same isotope
distribution.
Conductivity values of 10ꢁ3 M samples in methanol solution
(197 Oꢁ1 cm2 molꢁ1 (5), 200 Oꢁ1 cm2 molꢁ1 (6)) are in agree-
ment with the presence of 1 : 2 electrolyte compounds by
comparison with reported compounds (between 160 and
220 Oꢁ1 cm2 molꢁ1).[26,27]
Experimental
General Details
All reactions were carried out in vacuum line and using Schlenk
techniques. All reagents were commercial grade materials
without further purification. All solvents were previously dried
and distilled by standard methods.
Conductivity measurements were performed at room tem-
perature in dimethyl sulfoxide (DMSO) or methanol solutions
(10ꢁ3 M) employing a Crison i-micro CM 2200 conductimeter.
Elemental analyses (C, H, N) were carried out by the Chemical
Analyses Service of the Universitat Auto`noma de Bacelona on a
Carlo Erba CHNS EA-1108 instrument. Infrared spectra were
run on a Perkin–Elmer FT spectrophotometer series 2000 cmꢁ1
as KBr pellets or polyethylene films in the range 4000–
100 cmꢁ1 under a nitrogen atmosphere. 1H and 13C{1H}
NMR, HSQC, and NOESY spectra were run on a NMR-FT
Bruker AC-250 MHz spectrometer in CDCl3 solutions, at room
temperature. 195Pt{1H}NMR were recorded at 298 K in CDCl3
solutions, and at 77.42 MHz on a DPX-360 MHz Bruker spec-
trometer using aqueous solutions of [PtCl6]2ꢁ (0 ppm) as an
external reference, with delay times of 0.01 s. Chemical shifts
(d) are given in ppm. Mass spectra [MS-ESI(þ)] were obtained
with an Esquire 3000 ion trap mass spectrometer from Bruker
Daltonics.
The IR spectra of complexes 5 and 6 show absorption bands
assigned to the asymmetric and symmetric n(OCO) stretching
modes and the typical bands of polyetherpyrazole-derived
ligands.[28,29] The IR spectra of these complexes containing
the acetate anion were recorded between 1650 and 1400 cmꢁ1
,
allowing us to determine the coordination mode of the acetate
group. These complexes show a complicated spectrum in this
region and display bands between 1642–1591 and 1473–
1432 cmꢁ1, separated by D ¼ 205–126 cmꢁ1 (Fig. S1, Crystallo-
graphic data). These D values are consistent with the presence of
both ionic and coordinated acetate groups, pointing out the
presence of dimeric species.[30,41]
1H and 13C{1H} NMR spectra for complexes 5 and 6
recorded in CDCl3 solution show signals for coordinated ligands
(L1, L2) and acetate groups. In the 1H NMR spectra the bands
attributable to CH(pz) appears at 6.71 (5) and 7.08 (6) ppm;
moreover the signals that correspond to the protons of the chain
Npz(CH2CH2O)3CH3 appear between 4.74 and 3.19 ppm and the
protons of the methyl groups at 3.30 and 3.29 ppm. The 13C{1H}
NMR spectra display the signals of CH(pz) at 104.5 (5) and
105.9 (6) ppm, the signals of the chain Npz(CH2CH2O)3CH3
between 71.8 and 49.3 ppm, and the carbons of the methyl
groups at 59.0 and 58.9 ppm.
Samples of [PdCl2(CH3CN)2][42] and [PtCl2(CH3CN)2][43]
were prepared as described in the literature. 2-[5-Phenyl-1-
(3,6,9-trioxodecane)-1H-pyrazol-3-yl]pyridine (L1) and 3,5-
bis(2-pyridyl)-1-(3,6,9-trioxodecane)-1H-pyrazole (L2) ligands
were prepared according to the methods by us (Scheme 1)
(M. Guerrero, J. A. Pe´rez, V. Branchadell, et al., unpubl. data).
The methyl of the acetate groups display two signals in each
1
of the H NMR spectra and the 13C{1H} NMR spectra. These
1
Synthesis of the Complexes [PdCl2(L)] (L 5 L1 (1); L2 (2))
signals appear at 2.10 and 1.98 ppm (for H), and 23.0 and
22.9 ppm (for 13C) (5) and 2.13 and 2.05 (for 1H), and 23.4 and
22.8 ppm (for 13C) (6). The presence of two signals for each type
of proton could indicate the presence of two types of acetates:
bridged (2.10, 2.13 ppm; 23.0, 23.4 ppm) and ionic (1.98,
2.05 ppm; 22.9, 22.8 ppm). Unfortunately, no suitable single
crystals could be obtained for complexes 5 and 6.
A solution of [PdCl2(CH3CN)2] (0.088 g, 0.34 mmol) in 75 mL
of dry acetonitrile was treated with a solution of L1 or L2
(0.125 g, 0.34 mmol) dissolved in 5 mL of dry acetonitrile. After
12 h of stirring at room temperature, the solution was concen-
trated until a crystalline precipitate appeared. The complex was
obtained as orange needles. The solid was recrystallised from
dichloromethane. The solid was filtered off, washed with diethyl
ether (5 mL), and dried under vacuum.
Conclusions
1. (75 % yield). (Found:
C 46.5, H 4.7, N 7.6.
We have studied new Pd(II) and Pt(II) monomeric complexes
with
pyridine (L1) and 3,5-bis(2-pyridyl)-1-(3,6,9-trioxodecane)-
1H-pyrazole (L2) ligands (1–4). Additionally, the reaction of
[Pd(CH3COO)2] with L1 (5) and L2 (6) was also studied,
showing formation of dimeric structures with bridged acetates
C21H25N3Cl2O3Pd requires C 46.3, H 4.6, N 7.7 %). Conductivity
(1.0 ꢂ 10ꢁ3 M in DMSO): 25Oꢁ1 cm2 molꢁ1. nmax(KBr)/cmꢁ1
3114 n(C-H)aromatic (ar), 2899 n(C-H)aliphatic (al), 1625
(n(C¼C), n(C¼N))ar, 1458 (d(C¼C), d(C¼N))ar, 1133 n(C-O-
C)as, 1045 d(C-H)ar, vibration in the plain (ip), 784 d(C-H)ar,
vibration out of the plane (oop); (polyethylene, cmꢁ1): 492, 481 n
2-[5-phenyl-1-(3,6,9-trioxodecane)-1H-pyrazol-3-yl]

690
M. Guerrero et al.
(Pd-N), 349, 340 n(Pd-Cl). dH (CDC13, 250 MHz) 9.01 (1H, d,
3J ¼ 5.6, Hortho, py), 7.80–7.60 (3H, m, Hpy), 7.51–7.41 (5H, m,
Hph), 6.73 (1H, s, Hpz), 4.92 (2H, t, 3J ¼ 4.8, NCH2CH2O), 3.99
(2H, t, 3J ¼ 4.8, NCH2CH2O), 3.47 (8H, m, (CH2CH2O)2), 3.32
(3H, s, OCH3). dC (CDCl3, 62.9 MHz) 148.9 (Cortho, py), 136.7,
130.3, 129.1, 128.5, 122.2 (Cpy, Cph), 130.3–128.5 (Cph), 105.6
(Cpz), 71.7 (NCH2CH2O), 70.6–69.8 (CH2CH2O)2, 58.8 (OCH3),
49.3 (NCH2CH2O). m/z (ESIþ) 509 (100, [PdCl(L1)]þ).
Synthesis of the Complexes [Pd(Ac)(L)]2(Ac)2
(L 5 L1 (5); L2 (6))
The reactions were carried out under nitrogen atmosphere. To a
Schlenk flask containing deoxygenated warm CH2Cl2 (50 mL),
was added Pd(CH3COO)2 (0.045 g, 0.20 mmol) and L1 or L2
(0.074 g, 0.20 mmol). The resulting solution was stirred at room
temperature for 16 h and then concentrated on a vacuum line to
one-fifth of the initial volume; crystalline solids were obtained,
which were filtered off, washed with ethanol, and dried under
vacuum.
2. (72 % yield). (Found:
C 44.0, H 4.3, N 10.2.
C20H24N4Cl2O3Pd requires C 44.0, H 4.4, N 10.3 %). Conduc-
tivity (9.8 ꢂ 10ꢁ4 M in DMSO): 22 Oꢁ1 cm2 molꢁ1. nmax(KBr)/
cmꢁ1 3090 n(C-H)ar, 2875 n(C-H)al, 1611, 1571 (n(C¼C),
n(C¼N))ar, 1459, 1438 (d(C¼C), d(C¼N))ar, 1104 n(C-O-C)as,
1030 d(C-H)ar, ip, 783, 768 d(C-H)ar, oop; (polyethylene,
cmꢁ1): 479, 464 n(Pd-N), 356, 342 n(Pd-Cl). dH (CDC13,
250 MHz) 9.32 (1H, d, 3J ¼ 5.4, Hortho, py), 8.68 (1H, d,
3J ¼ 4.7, Hortho, py), 7.98–7.27 (6H, m, Hpy), 6.97 (1H, s, Hpz),
5.52 (2H, t, 3J ¼ 4.7, NCH2CH2O), 3.89 (2H, t, 3J ¼ 4.7,
NCH2CH2O), 3.41 (3H, s, OCH3), 3.31 (8H, m, (CH2CH2O)2).
dC (CDCl3, 62.9 MHz) 154.0 (Cortho, py), 150.9 (Cortho, py),
140.1, 139.3, 130.6, 126.7, 124.8, 121.4 (Cpy), 108.4 (Cpz), 71.8
(NCH2CH2O), 70.6–70.1 (CH2CH2O)2, 59.9 (OCH3), 52.8
(NCH2CH2O). m/z (ESIþ) 510 (100, [PdCl(L2)]þ).
5. (80 % yield). (Found:
C 50.7, H 5.1, N 7.3.
C50H62N6O14Pd2 requires C 50.7, H 5.3, N 7.1 %). Conductivity
(1.1 ꢂ 10ꢁ3 M in CH3OH): 197 Oꢁ1 cm2 molꢁ1. nmax(KBr)/
cmꢁ1 3068 n(C-H)ar, 2877 n(C-H)al, 1647 (n(C¼C), n
(C¼N))ar, 1635, 1591 n(COO)as, 1472 n(COO)s, 1465, 1432
(d(C¼C), d(C¼N))ar, 1102 n(C-O-C)as, 1079, 1031 d(C-H)ar,
ip, 787, 770 d(C-H)ar, oop; (polyethylene, cmꢁ1): 512 n(Pd-O),
485 n(Pd-N). dH (CDC13, 250 MHz) 8.15 (2H, d, 3J ¼ 5.0,
Hortho, py), 7.97–7.32 (6H, m, Hpy), 7.49–7.47 (8H, m, Hph),
6.71 (2H, s, Hpz), 4.31 (4H, t, 3J ¼ 4.7, NCH2CH2O), 3.85 (4H, t,
3J ¼ 4.7, NCH2CH2O), 3.51 (16H, m, (CH2CH2O)2), 3.30 (6H,
s, OCH3), 2.10 (6H, s, (CH3COO)bridged), 1.98 (6H, s,
(CH3COO)ionic). dC (CDCl3, 62.9 MHz) 178.7 (CH3COO)brid-
gedþionic, 178.5 (CH3COO)bridgedþionic, 149.6 (Cortho, py), 140.0,
130.3, 129.8, 128.9, 124.3, 121.0 (Cpy), 130.3–128.9 (Cph),
104.5 (Cpz), 71.8 (NCH2CH2O), 70.3, 69.7 (CH2CH2O)2, 59.0
(OCH3), 49.5 (NCH2CH2O), 23.0 (CH3COO)bridgedþionic, 22.9
(CH3COO)bridgedþionic. m/z (ESIþ) 529 (100, [Pd(Ac)(L1)]þ).
Synthesis of the Complexes [PtCl2(L)] (L 5 L1 (3); L2 (4))
A solution of [PtCl2(CH3CN)2] (0.118 g, 0.34 mmol) in 75 mL
of dry acetonitrile was treated with a solution of L1 or L2
(0.125 g, 0.34 mmol) dissolved in 10 mL of dry acetonitrile. The
resulting solution was stirred and heated at reflux for 24 h,
before concentrating on a vacuum line to one fifth of the initial
volume. The yellow solution was filtered off, washed with
diethyl ether (5 mL), and dried under vacuum.
6. (82 % yield). (Found:
C 48.5, H 4.9, N 9.4.
C48H60N8O14Pd2 requires C 48.6, H 5.1, N 9.5 %). Conductivity
(1.0 ꢂ 10ꢁ3 M in CH3OH): 200 Oꢁ1 cm2 molꢁ1. nmax(KBr)/
cmꢁ1 3075 n(C-H)ar, 2867 n(C-H)al, 1651 (n(C¼C),
n(C¼N))ar, 1642, 1602 n(COO)as, 1477 n(COO)s, 1473, 1437
(d(C¼C), d(C¼N))ar, 1107 n(C-O-C)as, 1062, 1035 d(C-H)ar,
ip, 789, 773 d(C-H)ar, oop; (polyethylene, cmꢁ1): 508 n(Pd-O),
483 n(Pd-N). dH (CDC13, 250 MHz) 8.56 (2H, d, 3J ¼ 4.8,
3. (68 % yield). (Found:
C 39.6, H 3.7, N 6.7.
C21H25N3Cl2O3Pt requires C 39.8, H 4.0, N 6.6 %). Conductivity
(1.2 ꢂ 10ꢁ3 M in DMSO): 36 Oꢁ1 cm2 molꢁ1. nmax(KBr)/cmꢁ1
3104 n(C-H)ar, 2868 n(C-H)al, 1619 (n(C¼C), n(C¼N))ar,
1466 (d(C¼C), d(C¼N))ar, 1122 n(C-O-C)as, 1032 d(C-H)ar,
ip, 782, 765 d(C-H)ar, oop; (polyethylene, cmꢁ1): 483, 471 n(Pt-
N), 348, 334 n(Pt-Cl). dH (CDC13, 250 MHz) 9.69 (1H, d,
3J ¼ 5.9, Hortho, py), 8.02–7.62 (3H, m, Hpy), 7.53–7.50 (5H,
m, Hph), 6.75 (1H, s, Hpz), 5.05 (2H, t, 3J ¼ 5.7, NCH2CH2O),
4.06 (2H, t, 3J ¼ 5.7, NCH2CH2O), 3.46 (8H, m, (CH2CH2O)2),
3.32 (3H, s, OCH3). dC (CDCl3, 62.9 MHz) 149.4 (Cortho, py),
139.0, 130.1, 129.7, 128.7, 124.5, 120.8 (Cpy, Cph), 106.8 (Cpz),
71.7 (NCH2CH2O), 71.6–70.0 (CH2CH2O)2, 58.8 (OCH3), 49.8
(NCH2CH2O). 195Pt{1H} (CDCl3, 77.0 MHz) ꢁ2187 (s). m/z
(ESIþ) 598 (100, [PtCl(L1)]þ).
3
Hortho, py), 8.19 (2H, d, J ¼ 4.7, Hortho, py), 7.83–7.05 (12H,
m, Hpy], 7.08 (2H, s, Hpz], 4.74 (4H, t, 3J ¼ 4.8, NCH2CH2O),
3
3.80 (4H, t, J ¼ 4.8, NCH2CH2O), 3.29 (6H, s, OCH3), 3.19
(16H, m, (CH2CH2O)2), 2.13 (6H, s, (CH3COO)bridged), 2.05
(6H, s, (CH3COO)ionic). dC (CDCl3, 62.9 MHz) 179.3
(CH3COO)bridgedþionic
,
179.1(CH3COO)bridgedþionic
,
149.8
(Cortho, py), 149.4 (Cortho, py), 138.3, 137.8, 124.3, 124.1,
123.4, 122.8 (Cpy), 105.9 (Cpz), 71.8 (NCH2CH2O), 70.6, 70.1
(CH2CH2O)2, 58.9 (OCH3), 49.3 (NCH2CH2O), 23.4
(CH3COO)bridgedþionic, 22.8 (CH3COO)bridgedþionic. m/z (ESIþ)
530 (100, [Pd(Ac)(L2)]þ).
4. (65 % yield). (Found:
C 37.6, H 3.7, N 8.7.
X-Ray Crystal Structure Analyses of Complex [PtCl2(L1)] (3)
C20H24N4Cl2O3Pt requires C 37.9, H 3.8, N 8.8 %). Conductiv-
ity (9.6 ꢂ 10ꢁ4 M in DMSO): 32 Oꢁ1 cm2 molꢁ1. nmax(KBr)/
cmꢁ1 3099 n(C-H)ar, 2881 n(C-H)al, 1621, 1591 (n(C¼C),
n(C¼N))ar, 1447 (d(C¼C), d(C¼N))ar, 1108 n(C-O-C)as, 1033
d(C-H)ar, ip, 790 d(C-H)ar, oop; (polyethylene, cmꢁ1): 465, 450
n(Pt-N), 342, 331 n(Pt-Cl). dH (CDC13, 250 MHz) 9.64 (1H, d,
3J ¼ 5.7, Hortho, py), 8.72 (1H, d, 3J ¼ 4.8, Hortho, py), 8.04–7.37
(6H, m, Hpy], 7.00 (1H, s, Hpz], 5.59 (2H, t, 3J ¼ 4.8,
Suitable crystals for X-ray diffraction of compound cis-
[PtCl2(L1)] (3) were obtained through crystallisation from
acetonitrile. Data were collected on an Enraf-Nonius CAD4
four-circle diffractometer using the v/2y scan technique.
Intensities were collected with graphite monochromatised Mo
˚
Ka radiation (l ¼ 0.71069 A). Unit cell parameters were deter-
mined from automatic centring of 25 reflections (128 , y ,218).
7037 reflections were measured in the range 2.318 # y # 29.988,
6763 of which were non-equivalent by symmetry (R int
(on I) ¼ 0.055). 3008 reflections were assumed as observed
applying the condition I .2s(I). Three reflections were mea-
sured every 2 h as orientation and intensity control, significant
intensity decay was not observed. Lorentz-polarisation and
absorption corrections were made.
3
NCH2CH2O), 3.94 (2H, t, J ¼ 4.8, NCH2CH2O), 3.41 (3H, s,
OCH3) 3.32 (8H, m, (CH2CH2O)2). dC (CDCl3, 62.9 MHz)
149.8 (Cortho, py), 149.5 (Cortho, py), 139.3, 137.2, 124.7,
124.2, 121.2 (Cpy), 105.0 (Cpz), 71.8 (NCH2CH2O), 70.4,
70.1 (CH2CH2O)2, 59.0 (OCH3), 50.2 (NCH2CH2O).
195Pt{1H} (CDCl3, 77.0 MHz) ꢁ2173 (s). m/z (ESIþ) 599
(100, [PtCl(L2)]þ).

Effect of Hybrid Ligand in Supramolecular Chemistry
691
The structure was solved by direct methods and refined
by the full-matrix least-squares method, using 6763 reflec-
tions (very negative intensities were not assumed).[44] The
function minimised was Sw!Fo|2 – |Fc|2|2, were w ¼ [s2(I) þ
(0.0386P)2]ꢁ1 and P ¼ (|Fo|2 þ 2|Fc|2)/3. All H atoms were
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 are linked. The final R(F) factor and R
(F2) values as well as the number of parameters and other details
concerning the refinement of the crystal structure are gathered in
Table 2.
(b) A. de Leon, M. Guerrero, J. Garc´ıa-Anto´n, J. Ros, M. Font-Bardia,
J. Pons, CrystEngComm 2013, 15, 1762.
[19] (a) M. Guerrero, J. Pons, J. Ros, M. Font-Bard´ıa, O. Vallcorba, J. Rius,
V. Branchadell, A. Merkoc¸i, CrystEngComm 2011, 13, 6457.
doi:10.1039/C1CE05626C
(b) S. Mun˜oz, M. Guerrero, J. Ros, T. Parella, M. Font-Bardia, J. Pons,
Cryst. Growth Des. 2012, 12, 6234. doi:10.1021/CG3014333
[20] V. Montoya, J. Pons, V. Branchadell, J. Garc´ıa-Anto´n, X. Solans,
M. Font-Bard´ıa, J. Ros, Organometallics 2008, 27, 1084. doi:10.1021/
OM7009182
[21] V. Montoya, J. Pons, V. Branchadell, J. Garc´ıa-Anto´n, X. Solans,
M. Font-Bard´ıa, J. Ros, Organometallics 2007, 26, 3183. doi:10.1021/
OM070093U
Crystallographic Data
[22] V. Montoya, J. Pons, X. Solans, M. Font-Bard´ıa, J. Ros, Inorg. Chim.
Acta 2006, 359, 25. doi:10.1016/J.ICA.2005.07.047
Crystallographic data for the structural analyses have been
deposited with the Cambridge Crystallographic Data Centre,
CCDC reference number CCDC 916483 for compound
[PtCl2(L1)] (3). Copies of this information may be obtained free
of charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ. (Fax: þ44 1223 33603); email: deposit@
ccdc.com.ac.uk www.htpp://ccdc.cam.ac.
[23] V. Montoya, J. Pons, V. Branchadell, J. Garc´ıa-Anto´n, X. Solans,
M. Font-Bard´ıa, J. Ros, Inorg. Chim. Acta 2007, 360, 625.
doi:10.1016/J.ICA.2006.08.058
[24] S. Mun˜oz, J. Pons, J. Ros, M. Font-Bard´ıa, C. A. Kilner, M. A.
Halcrow, Inorg. Chim. Acta 2011, 373, 211. doi:10.1016/J.ICA.
2011.04.027
[25] M. Guerrero, J. Pons, M. Font-Bard´ıa, T. Calvet, J. Ros, Aust. J. Chem.
2010, 63, 958. doi:10.1071/CH10040
[26] L. K. Thompson, F. L. Lee, E. J. Gabe, Inorg. Chem. 1988, 27, 39.
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[27] W. J. Geary, Coord. Chem. Rev. 1971, 7, 81. doi:10.1016/S0010-8545
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[28] D. H. Williams, I. Fleming, Spectroscopic Methods in Organic
Acknowledgements
This work has been financially supported by the Spanish Ministry of Culture
and Education (project CTQ 2007 6391/BQU and MAT2011–27225).
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