Molecular architectures of cationic [Pd(η3-C3H5)(pzbp2py)]+ complexes and BF4- and CF3 SO3- as counteranions (pzbp2py = 2-[3,5-bis(4-butoxyphenyl)pyrazol-1-yl]pyridine)

Article abstract of DOI:10.1016/j.jorganchem.2005.12.071

The crystal structures of two complexes containing the 2-[3,5-bis(4-butoxyphenyl)pyrazol-1-yl]pyridine (pz^bp2py) ligand bonded to the [Pd(η³-C₃H₅)]⁺ fragment and BF₄^- and CF₃ SO₃^- as counteranions (1 and 2, respectively) have been solved and their molecular architectures compared. The compounds exhibit a ²D network based on weak interactions in which the counterion plays an important role. The molecular layers in the ²D arrangement show interpenetration between the substituent-chains on the pyrazole rings. These features are also observed in related compounds bearing only one chain on the pyrazole ring.

Full text of DOI:10.1016/j.jorganchem.2005.12.071

Journal of Organometallic Chemistry 691 (2006) 2614–2622
www.elsevier.com/locate/jorganchem
Molecular architectures of cationic [Pd(g3-C3H5)(pzbp2py)]+
complexes and BF4ꢀ and CF3SOꢀ3 as counteranions
(pzbp2py = 2-[3,5-bis(4-butoxyphenyl)pyrazol-1-yl]pyridine)
a
a,
a
a
b
M.C. Torralba , M. Cano *, J.A. Campo , J.V. Heras , E. Pinilla a,b, M.R. Torres ,
c
c
J. Perles , C. Ruiz-Valero
a
Departamento de Quı´mica Inorga´nica I, Facultad de Ciencias Quı´micas, Universidad Complutense, E-28040 Madrid, Spain
Laboratorio de Difraccio´n de Rayos-X, Facultad de Ciencias Quı´micas, Universidad Complutense, E-28040 Madrid, Spain
b
c
Instituto de Ciencia de Materiales, CSIC, Cantoblanco, E-28049 Madrid, Spain
Received 12 November 2005; received in revised form 20 December 2005; accepted 20 December 2005
Available online 10 March 2006
Abstract
The crystal structures of two complexes containing the 2-[3,5-bis(4-butoxyphenyl)pyrazol-1-yl]pyridine (pzbp2py) ligand bonded to the
[Pd(g3-C3H5)]+ fragment and BF4ꢀ and CF3SOꢀ as counteranions (1 and 2, respectively) have been solved and their molecular architec-
3
tures compared. The compounds exhibit a 2D network based on weak interactions in which the counterion plays an important role. The
2
molecular layers in the D arrangement show interpenetration between the substituent-chains on the pyrazole rings. These features are
also observed in related compounds bearing only one chain on the pyrazole ring.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Palladium(II) complexes; Pyrazolylpyridine ligands; X-ray structure; Supramolecular architecture
1. Introduction
In addition, weaker interactions have also been
exploited in crystal engineering studies [3], and due to their
abundance in the crystal structures, their contribution
should also be considered in the design of supramolecular
architectures.
A variety of multidimensional frameworks have been
constructed by coordination bonds between multifunc-
tional ligands and metal ions in different coordination envi-
ronments. Other synthetic approaches such as those based
on hydrogen bonds or pꢁ ꢁ ꢁp interactions have also been
used and are well documented [1,2]. In general, supramo-
lecular architectures assembled by coordination bonds or
supramolecular interactions have been proposed to be use-
ful for more predictable control over directional assemblies
and packing in the solid state [1].
In previous works from our lab, we have found that the
crystallization process of complexes of the type [Pd(g3-
C3H5)(Hpz*)2]A containing the [Pd(g3-C3H5)]+ fragment
and pyrazole groups (Hpz* = 3,5-bis(4-butoxyphenyl)pyra-
zole Hpzbp2; 3,5-dimethyl-4-nitropyrazole HpzNO2) as co-
ligands was strongly controlled by hydrogen bonding
interactions established between the counterions, A, and
the NH pyrazolic groups [4,5]. By contrast, in the related
compounds [Pd(g3-C3H5)(pzRpy)]A (pzRpy = 2-[3-(4-alkyl-
oxyphenyl)pyrazol-1-yl]pyridine; A ¼ BFꢀ; PFꢀ; CF3SOꢀ),
4
6
3
the pzRpy ligands can only act as terminal ligands as they
form bidentate chelating species [6]. In the absence of
*
Corresponding author. Fax: +34 91 3944352.
E-mail address: mmcano@quim.ucm.es (M. Cano).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.12.071

M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
2615
NH groups, these ligands do not have supramolecular
interaction sites for molecular recognition through
NHꢁ ꢁ ꢁA bonds. In spite of these, the counterion still plays
an important role at a supramolecular level involving non-
conventional C–Hꢁ ꢁ ꢁF hydrogen bonds between neigh-
cantly modify the molecular assembly through the counter-
ion, at least in the D arrangement (Fig. 1).
1
In this work, the X-ray structures of the complexes
[Pd(g3-C3H5)(pzbp2py)]A ðA ¼ BF4ꢀ 1; CF3SOꢀ 2Þ con-
3
taining disubstituted pyrazole groups (pzbp2py = 2-
[3,5-bis(4-butoxyphenyl)pyrazol-1-yl]pyridine) have been
solved and the molecular assemblies discussed. We were
1
bouring entities which produce polymeric chains in a D
assembly (Fig. 1). Additional related interactions hold the
chains together defining molecular layers. These features,
which were observed in the crystal structures of
[Pd(g3-C3H5)(pzRpy)]BF4 (pzRpy = 2-[3-(4-hexyloxyphe-
nyl)pyrazol-1-yl]pyridine pzhppy; 2-[3-(4-decyloxyphe-
nyl)pyrazol-1-yl]pyridine pzdppy), allowed us to establish
that the bidentate pzRpy ligands and the counterion func-
tion as hydrogen-bond sources giving rise to a 2D supramo-
lecular assembly [6].
also interested in establishing how counterions such as
1
BFꢀ4 or CF3SOꢀ could contribute to the formation of D
3
assemblies through hydrogen-bond interactions involving
the F and/or O atoms. Further interactions were expected
2
to extend the dimensionality to a D framework.
2. Experimental
Since layer-like molecular assemblies in the solid state
can be related to the lamellar structures of liquid crystal
compounds, the above structural features are potentially
useful to establish structure/mesomorphic properties rela-
tionships in metallomesogenic coordination compounds
based on mesogenic or promesogenic pyrazolylpyridine-
type ligands [7].
Following these results, we are now interested in proving
that a similar structural behavior can be obtained in related
complexes with adequate counterions, thus contributing to
the design of layer-like structures based on weak non-
conventional hydrogen-bonds. Taking into account the
supramolecular structure of [Pd(g3-C3H5)(pzhppy)]BF4
[6], we expect that the presence of two substituents at the
3 and 5 positions of the pyrazole group should not signifi-
2.1. Materials and physical measurements
All commercial reagents were used as supplied. The
starting Pd-complex [Pd(l-Cl)(g3-C3H5)]2 was purchased
from Sigma–Aldrich and used as supplied. The ligand
2-[3,5-bis(4-butoxyphenyl)pyrazol-1-yl]pyridine (pzbp2py)
and compound 1 were prepared as described in the litera-
ture [4,8].
Elemental analyses for carbon, hydrogen, nitrogen and
sulphur were carried out by the Microanalytical Service
of the Complutense University. IR spectra were recorded
on a FTIR ThermoNicolet 200 spectrophotometer with
samples as KBr pellets in the 4000–400 cmꢀ1 region.
1H NMR spectra were performed on a Bruker AC-200
spectrophotometer (NMR Service of the Complutense
F
F
F
F
F
F
F
N
N
F
N
N
N
N
Pd
F
Pd
Pd
F
Pd
N
N
N
N
N
N
F
F
F
F
F
F
a
F
F
F
F
F
F
F
N
N
F
N
N
N
N
Pd
Pd
Pd
F
Pd
F
N
N
N
N
N
N
F
F
F
F
F
F
b
Fig. 1. (a) Schematic representation of the structure of [Pd(g3-C3H5)(pzRpy)]BF4 (pzRpy = 2-[3-(4-alkyloxyphenyl)pyrazol-1-yl]pyridine) [6]. (b) Sche-
matic representation of the proposed structure for [Pd(g3-C3H5)(pzR2py)]BF4 (pzR2py = 2-[3,5-bis(4-alkyloxyphenyl)pyrazol-1-yl]pyridine).

2616
M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
Table 1
University) from solutions in CDCl3. Chemical shifts d are
listed in ppm relative to TMS using the signal of the deuter-
ated solvent as reference (7.26 ppm), and coupling con-
stants J are in hertz. Multiplicities are indicated as d
(doublet), t (triplet), m (multiplet), br (broad signal). The
1H chemical shifts and coupling constants are accurate to
0.01 ppm and 0.3 Hz, respectively.
Crystal and refinement data for 1 and 2.
1
2
Empirical formula
Formula weight
Crystal system
Space group
C31H36BF4N3O2Pd C32H36F3N3O5SPd
675.84
738.13
Orthorhombic
Pbca
9.961(1)
19.824(2)
31.062(3)
Triclinic
P(ꢀ1)
˚
a (A)
10.774(1)
17.482(1)
18.548(1)
105.861(1)
90.560(2)
101.547(2)
3284.9(4)
4
˚
b (A)
2.2. Preparation of [Pd(g3-C3H5)(pzbp2py)]CF3SO3
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
To a solution of [Pd(l-Cl)(g3-C3H5)]2 (0.107 mmol,
39 mg) in 20 mL of acetone, AgSO3CF3 (0.214 mmol,
54.8 mg) was added. The mixture of reaction was stirred
at room temperature under nitrogen and absence of light
at least for six hours. Then the residue was separated by fil-
tration over celite and pzbp2py (0.214 mmol, 94.1 mg) dis-
solved in ca. 10 ml of dichloromethane was added to the
resulting colorless solution. After 24 h stirring at room
temperature under nitrogen, the solution was filtered over
celite/activated carbon and the solvent partially removed
in vacuo. The addition of hexane led to the crystallization
of colorless needles that were isolated by filtration, washed
with hexane and dried in vacuo. Yield: 60%.
3
˚
V (A )
6134(1)
8
173(2)
2768
1.464
0.662
0.50 · 0.40 · 0.30
x and /
(ꢀ14,ꢀ24,ꢀ30)
to (14,28,44)
3.76–31.09
37883
Z
T (K)
F(000)
296(2)
1512
1.492
0.689
0.25 · 0.12 · 0.04
x and /
(ꢀ12,ꢀ18,ꢀ21)
to (12,20,22)
1.14–25.00
25551
qcalc. (g cmꢀ3
)
l (mmꢀ1
)
Crystal dimensions (mm)
Scan technique
Data collected
h range (ꢁ)
Reflections collected
Independent reflections (Rint
Completeness to
maximum h (%)
Data/restraints/parameters
Observed reflections
[I P 2 r(I)]
)
9076 (0.0644)
92.0
11256 (0.0998)
97.4
Elemental analyses: found C 52.0, H 5.0, N 5.8, S 4.3%;
calculated for C32H36F3N3O5SPd: C 52.1, H 4.9, N 5.7, S
4.3%. IR (KBr, cmꢀ1): m(CN) 1610, c(CH)py 770,
m(SO3) + m(CF3) 1272–1253, ms(SO3) 1027. 1H NMR
9076/0/497
5895
11256/0/765
4139
GOF (F2)
1.077
0.809
3
4
Ra
RwF
0.0535
0.1202
0.647
0.0575
0.1272
0.915
(CDCl3; d in ppm; J, in Hz): 8.89 (dd, J = 5.4, J = 1.0,
3
3
4
b
1H, H6(py)), 7.81 (ddd, J = 8.5, J = 6.8, J = 1.7, 1H,
H4(py)), 7.59 (d, 3J = 8.8, 2H, Ho(C6H4)), 7.54 (ddd,
3J = 6.6, 3J = 5.4, 4J = 1.0, 1H, H5(py)), 7.41 (d,
3J = 8.8, 2H, Ho(C6H4)), 7.06 (d, 3J = 8.8, 2H,
Hm(C6H4)), 7.04 (d, 3J = 8.8, 2H, Hm(C6H4)), 6.99 (d,
3J = 8.6, 1H, H3(py)), 6.69 (s, 1H, H4(pz)), 5.70 (m,
ꢀ3
˚
Largest residual peak (e A
)
P
P
a
[jFoj ꢀ jFcj]/ jFoj.
P
P
2
2
1=2
b
f
½wðF 2o ꢀ F c2Þ ꢂ= ½wðF 2oÞ ꢂg
.
3
3
3Ja = 12.7, Js = 6.8, 1H, Hmeso(C3H5)), 4.06 (t, J = 6.4,
2H, OCH2), 4.05 (t, 3J = 6.3, 2H, OCH2), 4.05 (2H,
Hs(C3H5), masked by the OCH2 signals), 3.35 (br, 2H,
Ha(C3H5)), 1.83 (m, 4H, CH2), 1.54 (m, 4H, CH2), 1.01
Data for compound 1 were taken at low temperature
(173 K). The structure was solved by direct methods and
refined in the orthorhombic system (space group Pbca).
The refinement was made by full-matrix least-squares with
anisotropical thermal parameters for all non-hydrogen
atoms. In one of the butoxy chains, the three final atoms
(C29, C30 and C31) show disorder, occupying two alterna-
tive positions A and B with a probability value of 51% and
49%, respectively. The hydrogen atoms of this fragment as
well as the three hydrogen atoms bonded to C21 have been
calculated and refined as riding on their respective carbon
atoms. The remaining hydrogen atoms were located in a
difference Fourier synthesis, included and refined their
coordinates.
3
(t, J = 7.2, 6H, CH3).
2.3. X-ray structure determinations of
[Pd(g3-C3H5)(pzbp2py)]A (A ¼ BF 4ꢀ 1; CF 3SOꢀ 2)
3
Suitable pale yellow or colorless crystals of 1 and 2,
respectively, were grown by layering dichloromethane solu-
tions with hexane. The crystals were mounted on a Smart
CCD-Bruker diffractometer with graphite monochromated
˚
Mo Ka radiation (k 0.71073 A) operating at 50 kV and
The structure of 2 was solved by direct and difference
Fourier methods. Due to the existence of two crystallo-
graphic independent set of atoms which are apparently
equal, data collection of different crystals and refine-
ment with the original unit cell and a transform unit
20 mA. A summary of the fundamental crystal and refine-
ment data for these structures is given in Table 1.
In both cases, data were collected over an hemisphere of
the reciprocal space by combination of the three exposure
sets. Each exposure of 20 s covered 0.3ꢁ in x. The cell
parameters were determined and refined by a least-squares
fit of all reflections. The first 100 frames were recollected at
the end of the data collection to monitor crystal decay, and
no appreciable decay was observed.
˚
cell (a = 10.680(1), b = 10.771(1), c = 17.127(1) A; a =
80.158(2), b = 73.844(1), c = 60.299(1)ꢁ; V = 1642.5(3)
3
˚
A ) were carried out. The same structural model was
obtained in the acentric space group (P1) with the trans-

M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
2617
form unit cell, but the thermal parameters of many atoms
became negative in the refinement. Thus, the refinement
was made with the original cell by full-matrix least squares
on F2. All non-hydrogen atoms have been refined aniso-
tropically, except some carbon atoms of the butoxy chains
carbon atom and the oxygen atom is 73.6(3)ꢁ and
42.7(3)ꢁ for 2A and 2B, respectively.
The molecular structures of 1 and 2 consist of discrete
[Pd(g3-C3H5)(pzbp2py)]+ cations and BF4ꢀ or CF3SOꢀ
3
anions, respectively (Figs. 2 and 3). In both cases, the cat-
ionic entity shows the same structural skeleton. Table 2
lists selected bond distances and angles, and Table 3 recov-
ers the geometrical parameters for the C–Hꢁ ꢁ ꢁF/O interac-
tions responsible for the supramolecular arrangement.
The cations in 1 and 2 (2A and 2B) each exhibits a pyr-
azolylpyridine ligand bonded in a bidentate manner
through the N1 (N-pyrazole) and N3 (N-pyridine) atoms
to the metal center giving rise to a five-membered metallo-
cycle. The allyl ligand (p-bonded to the metal center) com-
pletes the coordination environment of the metal, which is
distorted square-planar, with the Pd atom deviating
and the fluorine atoms of the CF3SOꢀ group. Hydrogen
3
atoms were included in calculated positions and were
refined as riding on their respective carbon atoms.
All calculations were performed using SMART software
for data collection, SAINT for data reduction [9], and SHEL-
XTL to resolve and refine the structure [10].
The refinement converged to R values of 0.0535 and
0.0575 for 1 and 2, respectively. The largesꢀt 3residual peaks
˚
in the final difference map were 0.647 e A for 1, in the
vicinity of the C9 atom, and 0.915 e Aꢀ3 for 2, in the vicin-
˚
ity of the F1A atom.
˚
ꢀ0.088(2) A from the least-squares plane defined by the
3. Results and discussion
N1, N3, C1 and C3 atoms in the case of 1, and 0.087(1)
˚
and ꢀ0.090(1) A in 2A and 2B, respectively. The Pd1N1N3
The synthesis and characterization of compound 1 have
already been published by us [4]. Following a similar pro-
cedure, compound 2 was prepared from [Pd(g3-C3H5)(ace-
tone)2]CF3SO3, which was obtained in situ by reaction of
the dimer [Pd(l-Cl)(g3-C3H5)]2 and AgCF3SO3 in acetone
and Pd1C1C3 planes are almost parallel (the dihedral
angles are of 8.0(2)ꢁ, 7.2(2)ꢁ and 6.4(2)ꢁ for 1, 2A and
2B, respectively).
The Pd–N distances (Table 2) are similar to those found
in related compounds [4–6,11–13]. The Pd–N1 and Pd–N3
bonds form the basis of the five-membered chelate ring,
1
[11]. Elemental analysis and IR and H spectroscopic data
˚
agree with the proposed formulation (see Section 2).
Crystals of 1 and 2 suitable for X-ray diffraction were
obtained from dichloromethane/hexane solutions. The
structures of both compounds were unequivocally deter-
mined by single crystal X-ray diffraction.
Compound 2 presents two crystallographically indepen-
dent sets of atoms in the asymmetric unit (namely 2A and
2B), which show significant differences in the relative dispo-
sition of the butoxy chains. Thus, the angle between the
chains defined by the lines linking the corresponding CH3
with the Pd–N3 distance (mean value of 2.089 A) being
slightly shorter than the Pd–N1 one (mean value of
˚
2.109 A), in agreement with the expected difference in basi-
city of their respective heterocycles.
The C1C2C3 allyl group is slightly deviated from the
ideal geometry (i.e., the mean values of the C–C bond dis-
˚
tances and C–C–C angles are of ca. 1.39 A and 118ꢁ,
respectively; Table 2). The Pd–C(allyl) distances (2.092–
3
+
˚
2.126 A) are in the expected range for a [Pd(g -allyl)]
fragment with nitrogen ligands in trans position [5,6,11,12].
Fig. 2. ORTEP plot of 1 with 50% probability, showing the two alternative positions of C29, C30 and C31 atoms. Hydrogen atoms have been omitted for
clarity.

2618
M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
Fig. 3. ORTEP plot of 2A with 40% probability. Hydrogen atoms have been omitted for clarity. The ORTEP plot of 2B is similar and then it is not
depicted.
Table 2
Table 3
3
Selected bond distances (A) and angles (ꢁ) for [Pd(g -C3H5)(pzbp2py)]A
Geometrical parameters for the weak C–Hꢁ ꢁ ꢁF/O hydrogen-bond inter-
˚
ðA ¼ BFꢀ4 1; CF3SOꢀ 2Þ
actions (lengths in A and angles in degrees) for [Pd(g -C3H5)(pzbp2py)]A
3
˚
3
ðA ¼ BFꢀ4 1; CF3SOꢀ 2Þ
3
1
2A
2.101(7)
2B
2.107(6)
Contact
d(D–H)
d(Hꢁ ꢁ ꢁA)
d(Dꢁ ꢁ ꢁA)
\(D–Hꢁ ꢁ ꢁA)
Pd1–N1
Pd1–N3
Pd1–C1
Pd1–C2
Pd1–C3
C1–C2
2.118(2)
2.101(2)
2.123(3)
2.118(3)
2.122(3)
1.379(5)
1.393(5)
2.093(7)
2.111(8)
2.113(8)
2.126(8)
1.39(1)
2.074(6)
2.113(8)
2.109(8)
2.092(8)
1.39(1)
1
C13–Hꢁ ꢁ ꢁF4a
C4–Hꢁ ꢁ ꢁF4b
C6–Hꢁ ꢁ ꢁF2c
0.93(3)
0.95(3)
0.84(3)
2.54(3)
2.72(3)
2.59(3)
3.061(4)
3.149(4)
3.185(4)
116(2)
108(2)
129(3)
2
C2–C3
1.39(1)
1.37(1)
C17A–Hꢁ ꢁ ꢁO4Bd
C17B–Hꢁ ꢁ ꢁO3Ae
C13A–Hꢁ ꢁ ꢁO5Af
C6A–Hꢁ ꢁ ꢁF2Ag
a
0.93
0.93
0.93
0.93
2.70
2.55
2.72
2.67
3.22(1)
3.27(1)
3.32(1)
3.28(1)
120.8
134.4
123.1
123.1
N1–Pd1–N3
N1–Pd1–C1
N1–Pd1–C2
N1–Pd1–C3
N3–Pd1–C1
N3–Pd1–C2
N3–Pd1–C3
C1–Pd1–C2
C1–Pd1–C3
C2–Pd1–C3
C1–C2–C3
77.89(9)
77.0(3)
172.9(3)
143.8(4)
110.3(3)
103.9(3)
135.8(4)
172.2(3)
38.5(3)
77.5(3)
173.8(3)
143.3(4)
110.5(3)
103.2(3)
136.1(4)
170.9(3)
38.5(3)
68.4(3)
38.0(3)
118(1)
171.9(1)
144.2(1)
110.4(1)
103.6(1)
134.6(1)
171.5(1)
37.9(1)
67.9(1)
38.4(1)
117.6(4)
1 + 1/2 ꢀ x, y + 1/2, z + 1.
x ꢀ 1/2, 1 + 1/2 ꢀ y, 1 ꢀ z.
x + 1/2, 1 + 1/2 ꢀ y, 1 ꢀ z.
x, y + 1, z.
b
c
d
e
f
x, y ꢀ 1, z.
68.6(3)
38.3(3)
118.0(9)
1 ꢀ x, 2 ꢀ y, ꢀz.
g
x + 1, y, z.
The dihedral angle between the allyl plane (C1C2C3)
and the coordination plane defined by the Pd, N1 and
N3 atoms is 63.9(3)ꢁ for 1, and 63.3(7) and 62.2(7)ꢁ for
2A and 2B, respectively, with the allyl carbon atoms dis-
placed a mean value of 0.27 A with respect to the PdN1N3
plane.
The pyrazole and pyridine planes are twisted respect to
each other and form dihedral angles of 22.5(2)ꢁ, 19.0(2)ꢁ
and 19.7(2)ꢁ for 1, 2A and 2B, respectively. The benzene
planes of the substituents are also twisted with respect to
their own pyrazole planes with dihedral angles of 32.1(1)ꢁ
and 48.3(1)ꢁ for 1, 35.5(3)ꢁ and 51.7(2)ꢁ for 2A, and
35.6(2)ꢁ and 55.0(2)ꢁ for 2B. The largest angle in each com-
pound corresponds, as expected, to the benzene plane clo-
ser to the pyridine ring. In this disposition, the benzene
planes are twisted respect to each other at an angle of
74.2(1)ꢁ, 80.5(2)ꢁ and 85.5(2)ꢁ for 1, 2A and 2B,
respectively.
˚

M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
2619
Fig. 4. View of the chain of 1 along the b axis, showing the Pdꢁ ꢁ ꢁF and Cꢁ ꢁ ꢁF contacts.
At the supramolecular level, each BFꢀ4 anion in 1 is
attached to two neighbouring cations through weak coor-
dinative Pdꢁ ꢁ ꢁF1(x,y + 1,z + 1) and non-conventional
C13ꢁ ꢁ ꢁF4(1 + 1/2 ꢀ x,y + 1/2,z + 1) hydrogen-bond inter-
All the above structural features are similar to those
found in the related complex [Pd(g3-C3H5)(pzhppy)]BF4,
with a monosubstituted pyrazole group (pzhppy = 2-[3-(4-
hexyloxyphenyl)pyrazol-1-yl]pyridine) [6]. In this, the
Cꢁ ꢁ ꢁF hydrogen-bond interactions defined along the chains
˚
actions of 3.311(2) and 3.061(4) A, respectively (Table 3).
˚ ˚
(3.08 A) and interchains (3.27 A) both compare well with
These interactions are propagated along the b axis, thus
generating a polymeric chain with Pdꢁ ꢁ ꢁPd distances of
1
2
those found in 1 for the D and D assemblies, of 3.06
˚
˚
ca. 10.9 A, in which the molecules involved show an inverse
and 3.16 A, respectively. Therefore, as it had been pro-
orientation (Fig. 4).
posed, the double substitution at the 3 and 5 positions on
the pyrazole ring by alkyloxyphenyl substituents does not
significantly modify the molecular assembly in the solid
with respect to the analogous compounds containing only
one substituent at the 3 position on the pyrazole ring
(Fig. 1). In both cases, the tetrahedral BFꢀ4 anion appears
to be responsible for the molecular assembly, giving rise
to the formation of weak D networks.
Complex 2 exhibits similar structural features to 1.
However, in this case, each type of interaction defining
Further weak Cꢁ ꢁ ꢁF hydrogen-bond interactions from
different chains, involving the F2 and F4 atoms of the
BFꢀ4 anion and the C4 and C6 atoms of the pyridine ring
˚
[C4ꢁ ꢁ ꢁF4(x ꢀ 1/2,1 + 1/2 ꢀ y,1 ꢀ z) 3.149(4) A, C6ꢁ ꢁ ꢁF2-
˚
(x + 1/2,1 + 1/2 ꢀ y,1 ꢀ z) 3.185(4) A] are also observed
(Table 3). The chains are held together in layers, which
are almost parallel to the ab plane (Fig. 5). In this layer-like
structure the flexible chains are interdigitated, occupying
the space between the layers (Fig. 6).
2
Fig. 5. View of a layer of 1 in the ab plane. The contacts have been omitted for clarity.

2620
M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
Fig. 6. 2D network of 1, showing the interdigitation of the chains between layers.
the molecular assembly presents two values because
to the presence of two molecules per asymmetric unit.
At the molecular level, each [Pd(g3-C3H5)(pzbp2py)]+ unit
interactions, which are propagated along the a axis
(Fig. 7), generate a one-dimensional arrangement with
the Pd atoms showing a zig-zag distribution and Pdꢁ ꢁ ꢁPd
˚
in
2
interacts with its neighbouring counteranion
distances of ca. 6 A.
through a weak coordinative Pdꢁ ꢁ ꢁO5 interaction of ca.
Additional extended Cꢁ ꢁ ꢁF and Cꢁ ꢁ ꢁO interactions (the
˚
˚
3.90 A.
shortest distances are 3.27(1) and 3.33(1) A, respectively;
Each [Pd(g3-C3H5)(pzbp2py)]CF3SO3 entity interacts
Table 3) give rise to layers that lie almost parallel to the
2
with its neighbours through weak non-conventional hydro-
ac plane, thus generating a D network (Fig. 8) in which
˚
gen-bonds, C17Aꢁ ꢁ ꢁO4B(x,y + 1,z) of 3.22(1) A and
the flexible chains are interdigitated occupying the space
between the layers.
˚
C17Bꢁ ꢁ ꢁO3A(x,y ꢀ 1,z) of 3.27(1) A (Table 3). These

M.C. Torralba et al. / Journal of Organometallic Chemistry 691 (2006) 2614–2622
2621
Fig. 7. View of the chain of 2 along the a axis, showing the Pdꢁ ꢁ ꢁO and Cꢁ ꢁ ꢁO contacts.
Fig. 8. 2D network of 2 in the ac plane. The contacts have been omitted for clarity.

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4. Conclusions
References
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Hꢁ ꢁ ꢁF hydrogen bonds on the crystal structures of
[Pd(g3-C3H5)]+ complexes containing the 2-[3,5-bis(4-but-
oxyphenyl)pyrazol-1-yl]pyridine (pzbp2py) ligand and BFꢀ4
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3
of the weakness of the interactions, reflected on the C–
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organometallic complexes studied is responsible for the
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2
generation of weak D supramolecular networks.
The relative intermolecular orientations between the cat-
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orientation of the [Pd(g3-C3H5)(pzbp2py)]+ along the b or a
axis in 1 and 2, respectively, can be traced to C–Hꢁ ꢁ ꢁF and
C–Hꢁ ꢁ ꢁO/F bonding interactions related with the presence
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4
3
zag chains. Regarding the geometry of the counterions, the
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C–Hꢁ ꢁ ꢁF and C–Hꢁ ꢁ ꢁO/F interactions responsible for the
interchain bonding, which give rise to layer arrangements
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2
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of D networks.
Complexes 1 and 2 are new examples which show that a
detailed analysis of the nature of weak interactions should
also be taken into account when designing supramolecular
assemblies.
[7] M.J. Mayoral, M.C. Torralba, M. Cano, J.A. Campo, J.V. Heras,
Inorg. Chem. Commun. 6 (2003) 626.
5. Supplementary data
[8] J.A. Campo, M. Cano, J.V. Heras, M.C. Lagunas, J. Perles, E.
Pinilla, M.R. Torres, Helv. Chim. Acta 85 (2002) 1079.
[9] Siemens, SAINT: Data Collection and Procedure Software for the
SMART System, Siemens Analytical X-Ray Instrument Inc., Mad-
ison, WI, 1995.
The supplementary crystallographic data have been
passed to the Cambridge Crystallographic Data Centre
(CCDC deposition numbers 288062 and 288063 for 1 and
2, respectively).
[10] Bruker, SHELXTL, Version 6.1, Bruker Analytical X-Ray Systems,
2000.
Acknowledgments
´
´
[11] F. Gomez-de la Torre, A. de la Hoz, F.A. Jalon, B.R. Manzano, A.
´
´
´
Otero, A.M. Rodrıguez, M.C. Rodrıguez-Perez, Inorg. Chem. 37
(1998) 6606.
´
We are grateful to the Direccion General de Investi-
´
´
´
[12] F. Gomez-de la Torre, A. de la Hoz, F.A. Jalon, B.R. Manzano,
gacion/MEC of Spain (Project No. BQU2003-07343) for
´
´
A.M. Rodrıguez, J. Elguero, M. Martınez-Ripoll, Inorg. Chem. 39
financial support. We also thank to Comunidad de Madrid
for financial support (Project GR/MAT/0511/2004) and
the contract to M.C.T.
(2000) 1152.
[13] M.C. Torralba, M. Cano, S. Go´mez, J.A. Campo, J.V. Heras, J.
Perles, C. Ruiz-Valero, J. Organomet. Chem. 682 (2003) 26.