Study of the coordination behaviour of (3,5-diphenyl-1H-pyrazol-1-yl) ethanol against Pd(II), Zn(II) and Cu(II)

Article abstract of DOI:10.1016/j.ica.2011.04.027

A new easily synthetic route with a 96% yield of ligand 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol (L) is obtained. The reactivity of L against Pd(II), Zn(II) and Cu(II) leads to [PdCl₂(L)₂] (1), [ZnCl₂(L)] (2) and [CuCl(L′)]

Full text of DOI:10.1016/j.ica.2011.04.027

Inorganica Chimica Acta 373 (2011) 211–218
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Inorganica Chimica Acta
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Study of the coordination behaviour of (3,5-diphenyl-1H-pyrazol-1-yl)ethanol
against Pd(II), Zn(II) and Cu(II)
a
Sergio Muñoz a,d, Josefina Pons a, , Josep Ros , Mercè Font-Bardia b,c, Colin A. Kilner d, Malcolm A. Halcrow d,*
⇑
a Departament de Química, Unitat de Química Inorgànica, Universitat Autònoma de Barcelona, Bellaterra, 08193-Barcelona, Spain
b Cristalꢀlografia, Minerologia i Depòsits Minerals, Universitat de Barcelona, Martí i Franquès s/n, 08028-Barcelona, Spain
c Unitat de Difracció de RX, Serveis Científico Tècnics, Universitat de Barcelona, Martí i Franqués s/n, 08028-Barcelona, Spain
d School of Chemistry, The University of Leeds, Woodhouse Lane, Leeds, W Yorkshire LS2 9JT, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
A new easily synthetic route with a 96% yield of ligand 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol (L) is
obtained. The reactivity of L against Pd(II), Zn(II) and Cu(II) leads to [PdCl2(L)2] (1), [ZnCl2(L)] (2) and
[CuCl(L0)]2 (3) (L0 is the ligand L without alcoholic proton), respectively. According to the different geom-
etries imposed by the metallic centre and the capability of L to present various coordination links, it has
been obtained complexes with square planar (1 and 3) or tetrahedral (2) geometry and different nucle-
arity: monomeric (1 and 2) or dimeric (3). Complete characterisation by analytical and spectroscopic
methods, resolution of L and 1–3 by single-crystal X-ray diffraction and magnetic studies for complex
3 are presented.
Received 13 December 2010
Received in revised form 11 April 2011
Accepted 15 April 2011
Available online 23 April 2011
Keywords:
Hybrid N,O ligand
Palladium(II)
Zinc(II)
Ó 2011 Elsevier B.V. All rights reserved.
Copper(II)
X-ray structures
Magnetic properties
1. Introduction
and in the position 1 by hydroxyalkyl chain N-(CH2)x –OH (x = 1,
2 or 3) and N–(CH2)y–S–(CH2)z –OH (y = 2, z = 2 and y = 2, z = 3)
The research in coordination chemistry has grown progressively
during the last decades. The potential application of hybrid ligands
which permits to connect organic molecules to metals by two differ-
ent heteroatoms (N, S, O, P, etc.) to form metallocycles has focused
much interest. It is well known that the relationship between the
steric and electronic preferences to metal ion and the coordination
properties of the ligand plays an important role in the structure of
the compounds. In this context, many ligands that contain a flexible
bridge between the active centres can adapt better to the specific
preferences of different metal ion in different ways. In particular,
the coordination behaviour of N-pyrazole ligands has been inten-
sively studied for its potential applicability to different fields, phar-
maceutical, catalyst and magnetic properties and others. These
studies are extensively reported in the literature [1].
In the last 10 years, our group has focused our aims in the syn-
thesis and characterisation of new N-pyrazole 1,3,5-trisubstitued
ligands and we have studied their coordination behaviour with
transition metals [2]. One of our research lines is the synthesis
and characterisation of new N-pyrazole ligands substituted in the
positions 3 and 5 by –H, –CH3, –CF3, –pyridine or –phenyl groups
(Fig. 1) [3].
In order to continue with this investigation, our goal is synthe-
sise and characterise the ligand 2-(3,5-diphenyl-1H-pyrazol-1-
yl)ethanol (L) and study their coordination behaviour against
Pd(II), Zn(II) and Cu(II). Ligand L has been reported previously by
Bondavalli et al. [4]. In their work, these authors presented the syn-
thesis of the ligand L and other related ligands and the study of its
depressive, anthiarritmic and analgesic properties. Also, in 2008,
Jiang et al. publish a work where described the synthesis of the li-
gand L, in one step, for reaction between benzoylchloride, the al-
kyne appropriate and 2-hydroxyethyl hydrazine in presence of
CuI/[PdCl2(PPh3)2] as catalyst with 68% yield [5].
In this paper, the complete characterisation of L and its com-
plexes are reported and the discussion is focused on the NMR,
magnetic, crystallographic and magnetic properties.
2. Results and discussion
2.1. Synthesis and characterisation of 2-(3,5-diphenyl-1H-pyrazol-1-
yl)ethanol (L)
⇑
Ligand L is described in the literature by Bondavalli et al. [4] and
Jiang co-workers [5]. However, in this paper, we reported a new
Corresponding authors. Fax: +34 93 581 31 01.
E-mail address: Josefina.Pons@uab.cat (J. Pons).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.04.027

212
S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
R
R
R
R
R = H, CH3, CF3, pyridine, phenyl
x = 1, 2, 3
OH
x
N
N
N
N
N4b
N5b
O1a
R = CH3
N5d
y, z = 2
N4d
S
y
OH
O1b
z
y = 2, z = 3
N5a
Fig. 1. N-pyrazole, O-alcohol ligands developed previously in our group.
N4a
O1c
easily one-step synthetic route with a 96% yield. A solution of 1,3-
diphenylpropan-1,3-dione and 2-hydroxiethylhydrazine (1:1.3) in
dry toluene is refluxed in a Dean-Stark apparatus during 12 h.
The resulting solution is evaporated to dryness obtaining a white
crystalline solid that corresponds to L ligand (Scheme 1). The com-
pound has been characterised by elemental analysis, mass spec-
trometry, IR, 1H, 13C{1H}, COSY, HSQC and NOESY NMR
experiments. All of them are in agreement with expected proposed
ligand [4–6].
O1d
N5c
N4c
The structure of L is confirmed by single crystal X-ray diffrac-
tion from prismatic crystals obtained by the slow evaporation of
a nitromethane solution of L. ORTEP picture and selected bonds
distances and angles are shown in Fig. 2 and Table 1. The asymmet-
ric unit of the structure of L contains four unique molecules con-
nected by hydrogen bonds between the proton of the alcohol
(CH2–OH) and the free pair electrons of the pyrazole (O1–HꢀꢀꢀN5).
These interactions permit to create a supramolecular structure in
Fig. 2. ORTEP drawing of
L showing all non-hydrogen atoms and numbering
scheme; 50% probability amplitude displacement ellipsoid shown. Lines (ꢀꢀꢀ) show
hydrogen bonds.
2.2. Synthesis and general characterisation of complexes 1–3
Treatment of [PdCl2(CH3CN)2], ZnCl2 and CuCl2 with L lead to
compounds [PdCl2(L)2] (1), [ZnCl2(L)] (2) and [CuCl(L0)]2 (3) (L0,
the ligand L without alcoholic proton group), respectively (Scheme
1). Compounds 1 and 3 have been obtained using a 1:1 metal:li-
a
zig-zag disposition. The distances and the angles O–HꢀꢀꢀN
[1.899–1.953 Å; 173–178°] are in agreement with other values de-
scribed in the literature [7].
OH
Ph
N
Cl
N
Ph
1/2 [PdCl2(CH3CN)2]
CH2Cl2, 12h, -CH3CN
Pd
(1)
1/2
Ph
Cl
N
N
Ph
HO
Ph
H
N
H2N
OH
N
OH
Cl
N
Ph
Ph
(2)
ZnCl2, C2H5OH
Ph
dry toluene, Dean-Stark, 12h
-2H2O
+
N
N
Zn
OH
HC(OC2H5)3, 12h
Cl
O
O
L
Ph
Ph
Ph
N
N
O
Cl
Cl
Ph
CuCl2, CH3NO2
12h, -HCl
(3)
Cu
Cu
1/2
N
O
Ph
N
Ph
Scheme 1.

S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
213
Table 1
spectrum of free ligand in the aromatic and methyl regions. Never-
theless, the two compounds show a significant change of the mul-
tiplicity of the signal of the protons CH2–OH. The free ligand
presents the signal as a triplet at d = 3.96 ppm but when the ligand
is coordinated to the metallic centre the signals appear as multi-
plets [3.93 (1), 3.87 (2) ppm]. The change in the multiplicity could
be caused by the increase of the rigidity of the chain N–CH2CH2–
OH when the ligand coordinates to the metal centre. In 2, the for-
mation of a chelate ring between L and Zn(II) ion could explain the
difficult of the chain to rotate. On the other hand, 1 does not form a
chelate between L and the Pd(II), but the rigidity could be imposed
by the formation of hydrogen bonds between the proton CH2–OH
and the chlorine atoms. The signal of the proton O–H of compound
1 appears as a multiplet at d = 2.07 ppm and the distance and angle
values between O1–H10ꢀꢀꢀCl2 [2.491 Å, 163.25°] are in agreement
with this hypothesis.
Distances (Å) and angles (°) of hydrogen bonds of L.
O–HꢀꢀꢀN
O–H (Å)
O–HꢀꢀꢀN (Å)
OꢀꢀꢀN (Å)
O–HꢀꢀꢀN (°)
O1(A)–H1(A)ꢀꢀꢀN(5B)
O1(B)–H1(B)ꢀꢀꢀN(5C)
O1(C)–H1(C)ꢀꢀꢀN(5D)
O1(D)–H1(D)ꢀꢀꢀN(5A)
0.906
0.933
0.895
0.914
1.906
1.899
1.953
1.918
2.812
2.828
2.846
2.828
178.35
173.84
175.24
173.71
gand ratio and compound 2 with a 1:2 metal:ligand ratio. The sol-
ubility of starting compounds has imposed the solvents used for
synthesis (dichloromethane for 1, ethanol for 2 and nitromethane
for 3). The deprotonation of the L ligand in the synthesis of com-
pound 3 has occurred spontaneously.
Compounds 1–3 were characterised by elemental analysis,
mass spectrometry, conductivity measurements, IR spectroscopy
and single crystal X-ray diffraction. Also, compounds 1 and 2 have
been characterised by NMR spectroscopy employing CDCl3 and
CD3OD, respectively, while compound 3 has been characterised
by magnetic measurements and EPR in solid and in a frozen solu-
tion of nitromethane.
Elemental analyses of 1–3 are consistent with the formula pre-
dicted. MS-ESI(+) of 1 gives peaks with m/z values of 671 (100%)
and 633 (85%), attributable to [PdCl(L)2]+ and [Pd(L2)-H]+, respec-
tively. Compound 2 presents one peak at 363 (100%) corresponding
to [ZnCl(L)]+, while 3 shows peak values at 691 (4%) and 591
(100%), corresponding to [Cu2Cl(L)2]+ and [Cu(L)2]+, respectively.
The molar conductivity of 10ꢁ3 M solutions of compounds 1 and
2 in acetone and acetonitrile, respectively, shows values between 4
2.3. Magnetic susceptibility and EPR measurements of 3
The variable temperature magnetic susceptibility behaviour of a
powder sample of 3 is consistent with a strongly antiferromagnet-
ically coupled dinuclear compound (Fig. 3). At 300 K the compound
shows
v
MT = 0.19 cm3 molꢁ1 K, substantially less that the spin-only
value for two weakly interacting Cu(II) ions (0.75 cm3 molꢁ1 K) [8].
v
MT decreases further upon cooling, reaching a value of
0.02 cm3 molꢁ1 K at 5 K. These data were modelled by the Blea-
ney–Bowers equation for a dimer of two S = ½ ions (Eq. (1), which
uses the H = ꢁ2J(S1ꢀS2) Hamiltonian convention) [11].
ꢂ
ꢀ
ꢁꢃ
and 12
X
ꢁ1 cm2 molꢁ1, attributable to non-electrolyte compounds
vM
¼
3 þ exp
ꢁ1ð1 ꢁ
q
Þ þ
q
ð1Þ
2Ng2b2
kT
ꢁ2J
Ng2b2
2kT
[8]. The molar conductivity of compound 3 was not measured the
conductivity because of the low solubility of the compound in the
typical solvents. The IR spectra of the complexes 1–3 in the range
4000–400 cmꢁ1, show that L ligand is coordinated to metallic cen-
tre. The most characteristic bands are those attributable to pyraz-
kT
where J is the superexchange coupling constant, N is Avogadro’s
number, b is the Bohr magneton, k is Boltzmann’s constant and
q
is the mole fraction of a mononuclear paramagnetic impurity. A
good fit to the data was obtained, yielding J = ꢁ286(3) cmꢁ1 and
olyl group, [m(C@C), m(C@N)], [d(C@C), d(C@N)], and d(C–H)oop [9].
q
= 0.08(1) (Fig. 3). A fixed g value of 2.10 was employed in this cal-
It is word noting that, in the IR spectra of compounds 1 and 2, a
broad band appears between 3500 and 3400 cmꢁ1, showing the
culation, based on the EPR spectrum of the compound (see below).
This J value is in good agreement with Haase’s magnetostructural
correlation for [Cu2(OR)2]2+ complexes (R = alkyl), which predicts
J ꢂ ꢁ310 cmꢁ1 for the observed average Cu–O–Cu bridge angle in
3 of 100.6° (see below) [12].
presence of the alcohol group
and position of this band could indicate if hydrogen bond interac-
tions are present [10]. In 3, the band attributable to (O–H) is not
m(O–H). Interestingly, the shape
m
observed, due to that in this complex the group O–H is
The X-band EPR spectrum of a powder sample of 3 at 120 K
shows a weak unsymmetric peak at g = 2.10, a typical value for a
Cu(II) compound (Fig. 4, top) [13]. There is some structure on the
low-field side of this peak, which may correspond to a poorly re-
solved g|| component of the resonance, split by hyperfine coupling
to one or both of the copper nuclei (63Cu and 65Cu both have nucle-
ar spin I = 3/2). However, this could not be unambiguously inter-
preted. Dicopper(II) compounds often show a characteristic ‘‘half-
field’’ resonance near 1500 G, corresponding to a spin-forbidden
deprotonated.
The 1H, 13C{1H} and bidimensional NMR studies (COSY, NOESY
and HSQC) of 1 and 2 give information about the disposition of
the ligand connected to the metal in solution. The 1H and 13C{1H}
NMR of 1 and 2 do not show important differences against the
D
mS = 2 transition between the mS = ꢁ1 and +1 Zeeman levels
[13]. Such a peak was not detected for 3. This behaviour is consis-
tent with a strong antiferromagnetism. The S = 0 magnetic ground
state of the compound is essentially fully populated at the temper-
ature of the EPR measurement (120 K), so the spin-forbidden tran-
sition between the Zeeman levels of the S = 1 excited spin state was
not observed.
In frozen nitromethane solution, the EPR spectrum of 3 now has
resolved axial symmetry, with g|| = 2.24, g\ = 2.07 and
A||{63,65Cu} = 170 G (Fig. 4, bottom). This spectrum is typical of a
mononuclear Cu(II) centre, with a square planar, square pyramidal
1
or octahedral coordination geometry (and a fdx2
g
electron con-
ꢁy2
figuration) [13]. This spectrum strongly implies that 3 does not re-
tain its dinuclear structure in this solvent, because decomposes to
one or more mononuclear species.
Fig. 3. Plot of vMT vs. T (circles) for compound 3. The solid lines represent best fits
of the data to the Bleaney–Bowers equation; see text for details and fitting
parameters.

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S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
C8
C7
C9
C16
C17
C4
C15
C3
C5
C6
C10
C12
C11
C14
C13
N2
N1
Zn1
C2
Cl1
C1
Cl2
O1
2
Fig. 6. ORTEP drawing of 2 showing all non-hydrogen atoms and numbering
scheme; 50% probability amplitude displacement ellipsoid shown.
Fig. 4. X-band EPR spectra of
3 at 120 K. Top, a powder sample; bottom, a
nitromethane solution of the compound.
N9
N28
N8
N29
2.4. Crystal and molecular structure of 1–3
Cu2
The structures of 1–3 were confirmed by single crystal X-ray
diffraction.
ORTEP pictures and selected bond lengths (Å) and angles values
(°) are shown in Figs. 5–7 and Table 2.
O5
O25
Prismatic orange crystals of 1 have been obtained by the slow
evaporation of a chloroform solution of this compound. The struc-
ture of 1 (Fig. 5, table 2) consists of discrete Pd(II) molecules con-
nected by hydrogen bonds. The Pd(II) is linked to two molecules of
Cu1
Cl3
Cl4
3
Fig. 7. ORTEP drawing of 3 showing all non-hydrogen atoms and numbering
scheme; 50% probability amplitude displacement ellipsoid shown. Solvent mole-
cules are omitted for clarity.
O1
N2
Pd1
L via
j
1-Npyrazole and finishes its coordination with two chlorine
Cl1
atoms in a trans disposition. The Pd(II) atom has a square-planar
geometry. The values of distances Pd–N [2.033(2), 2.009(3) Å]
and Pd–Cl [2.2972(13), 2.3118(13) Å] are in agreement with the
values described in the literature: Pd–N [1.989–2.042 Å] and Pd–
Cl [2.280–2.349 Å] [6]. Moreover, 1 presents intermolecular hydro-
gen bonds interactions between O(1)–H(10)ꢀꢀꢀCl(2) creating a 1-D
chain (Fig. 8). The distances H(10)ꢀꢀꢀCl(2) [2.491 Å] and O(1)ꢀꢀꢀCl(2)
[3.245 Å] and the value of the angle O(1)–H(10)ꢀꢀꢀCl(2) [163.25°]
are in agreement with the values described in the literature [7].
As our knowledge, 56 crystalline structures of Pd(II) compounds
with the [2Npz, 2Cl] core are described in the literature [7]. Twenty-
six of them show an empirical formula [PdCl2B2] (B = derived pyr-
azole ligand), where the metallic centre is connected to ligands B
N22
Pd2
O2
Cl2
via
j
1-Npz and finishes its coordination with two chlorine atoms
1
in a -trans disposition [7].
Prismatic colourless crystals of 2 where obtained from a meth-
anol:diethyl ether solution. The structure consists of discrete Zn(II)
Fig. 5. ORTEP drawing of
scheme; 50% probability amplitude displacement ellipsoid shown.
1 showing all non-hydrogen atoms and numbering

S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
215
Table 2
Selected bond lengths (Å) and angles (°) of 1–3.
1
2
3
Pd(1)–N(2)
Pd(2)–N(22)
Pd(1)–Cl(1)
Pd(2)–Cl(2)
2.033(2)
2.009(3)
2.2972(13)
2.3118(13)
0.78(5)
2.491(5)
3.245(3)
180.00(12)
180.00(14)
180.0
Zn(1)–N(2)
Zn(1)–O(1)
Zn(1)–Cl(1)
Zn(1)–Cl(2)
N(2)–Zn(1)–O(1)
N(2)–Zn(1)–Cl(1)
O(1)–Zn(1)–Cl(1)
N(2)–Zn(1)–Cl(2)
2.025(3)
2.105(3)
Cu(1)–O(5)
Cu(1)–O(25)
Cu(1)–Cl(4)
Cu(1)–Cl(3)
Cu(2)–O(5)
Cu(2)–O(25)
Cu(2)–N(29)
Cu(2)–N(9)
O(5)–Cu(1)–O(25)
Cl(3)–Cu(1)–Cl(4)
O(5)–Cu(2)–O(25)
N(9)–Cu(2)–N(29)
1.9631(17)
1.9815(17)
2.2473(7)
2.2565(7)
1.8982(17)
1.9115(17)
1.957(2)
1.982(2)
75.59(7)
98.31(3)
78.77(7)
2.1981(13)
2.2007(13)
92.15(12)
114.59(11)
100.78(11)
115.66(11)
O(1)–H(10)
H(10)ꢀꢀꢀCl(2)
O(1)ꢀꢀꢀCl(2)
N(2)–Pd(1)–N(2)
N(22)–Pd(2)–N(22)
Cl(1)–Pd(1)–Cl(1)
Cl(2)–Pd(2)–Cl(2)
O(1)–H(10)ꢀꢀꢀCl(2)
180.0
163.25(5)
99.43(9)
Fig. 8. 1-D chain of 1 created by hydrogen bonds.
molecules linked by van der Waals forces (Fig. 6, Table 2). The envi-
ronment around Zn(II) centre consists of two chlorine atoms and
[2.025(3) Å] and Zn–Cl [2.1981(13), 2.2007(13) Å] and the angles
N–Zn–O [92.15(12)°] and N–Zn–Cl [114.59(11)°, 115.66(11)°] are
in agreement with the values described for similar compounds in
the literature: Zn–N [1.997–2.144 Å], Zn–Cl [2.144–2.269 Å], N–
Zn–O [83.379°–99.439°] and N–Zn–Cl [101.299°–122.894°] [7].
one L ligand coordinated via
metallocycle with a distorted boat conformation. The Zn(II) centre
has distorted tetrahedral geometry. The distances Zn–N
j
2-N,O building a six-membered
a
Fig. 9. View of Cu1ꢀꢀꢀCl4 interaction of 3.

216
S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
However, the distance Zn1–O1 [2.105(3) Å] presents a higher value
than the values described in the literature: Zn–O and Zn–OH
[1.915–2.060 Å] [7].
plexes 1 and 2 that maintain the same structure in solid and
solution.
In the literature, there are described 96 compounds of Zn(II)
with the [Npz, Oalcohol, 2Cl] core [7], 34 of them are monomeric com-
4. Experimental
pounds and the metallic centre is linked by ligand via j
2-N,O form-
4.1. General details
ing metallocycles of five, six and seven members. In all cases, the
geometry around Zn(II) is distorted tetrahedral.
All reagents were commercial grade and were used without
further purification. The elemental analyses (C, H, N) were carried
out by the staff of the Chemical Analysis Service of the Universi-
tat Autònoma de Barcelona, or the University of Leeds microana-
lytical service, using a Carlo Erba CHNS EA-1108 instrument
separated by chromatographic column and thermoconductivity
detector. Conductivity measurements were performed at room
temperature in 10ꢁ3 M acetonitrile or acetone solutions employ-
ing a CyberScan CON 500 (Eutech Instrument) conductimeter.
Infrared spectra were run on a Perkin Elmer FT-2000 spectropho-
tometer as KBr pellets. The 1H and 13C{1H} NMR spectra and bidi-
mensional NMR spectra were run on a NMR-FT Bruker AC-250
spectrometer. All NMR experiments were recorded on CDCl3 or
CD3OD solvents under nitrogen. 1H and 13C{1H} NMR chemical
shifts (d) were determined relative to internal TMS and are given
in ppm. Electrospray Mass spectra (ESI+) were carried out by the
staff of the Chemical Analysis Service of the Universitat Autòno-
ma de Barcelona on an Esquire 3000 ion trap mass spectrometer
from Bruker Daltonics. Mass experiments were done on CH3CN,
CH3CN/H2O or CH3NO2 solvents. Variable temperature magnetic
susceptibility measurements were performed by Dr. Harry Blythe
(University of Sheffield, UK). A Quantum Design SQUID magne-
tometer was employed, using an applied field of 1000 G. A dia-
magnetic correction for the sample was estimated from Pascal’s
constants [11]. A diamagnetic correction for the sample holder
was also applied. Observed and calculated data were refined
using the program SIGMAPLOT [15]. X-band EPR spectra were run
using a Bruker EMX spectrometer, at a microwave frequency of
9.54 GHz. The precursor compounds ZnCl2 and CuCl2 are com-
mercially available and the compound [PdCl2(CH3CN)2] is pre-
Finally, green prismatic crystals of 3 were obtained by slow evap-
oration of a solution of nitromethane:diethyl ether of 3. The struc-
ture consists of a bimetallic Cu(II) complex linked by van der
Waals forces and the crystalline structure contains nitromethane
molecules (Fig. 7, Table 2). The Cu2 is connected via j
2-N,O to two li-
gands in a head-to-head arrangement generating two six-mem-
bered metallocycles with a distorted boat conformation. Each
ligand has lost its hydroxyl group proton and the oxygen connects
the Cu2 with Cu1 building a new four-membered metallocycle. Fi-
nally, Cu1 finishes its coordination with two chlorines in a cis dispo-
sition. The Cu(II) centres have a distorted square-planar geometry
observed by the values of the angles Cl(3)–Cu(1)–Cl(4) [98.31(3)°],
O(5)–Cu(1)–O(25) [75.59(7)°], O(5)–Cu(2)–O(25) [78.77(7)°] and
N(9)–Cu(2)–N29 [99.43(9)°] and by the values of the distances be-
tween Cu1 and the plane O(5)–O(25)–Cl(3)–Cl(4) [0.109 Å] and
Cu2 and the plane N(9)–N(29)–O(5)–O(25) [0.044 Å]. The values of
the distances Cu(2)–N(9) [1.982(2) Å], Cu(2)–N(29) [1.957(2) Å],
Cu(1)–Cl(3) [2.2565(7) Å], Cu(1)–Cl(4) [2.2473(7) Å], Cu(1)ꢀꢀꢀCu(2)
[2.9831(4) Å], the dihedral angle between the planes O(5)–O(25)–
Cl(3)–Cl(4) and N(9)–N(29)–O(5)–O(25) [27.93°]. All the data de-
scribed below are in agreement with the values of similar structures
described in the literature [14].
The oxo bridges Cu(2)–O(25)–Cu(1) and Cu(2)–O(5)–Cu(1) are
asymmetric and the values of the distances Cu(1)–O(5)
[1.9631(17) Å] and Cu(1)–O(25) [1.9815(17) Å] are slightly higher
than the values of the distances Cu(2)–O(5) [1.8982(17) Å] and
Cu(2)–O(25) [1.9115(17) Å]. Finally, compound 3 shows a weak ax-
ial intermolecular interaction Cu(1)ꢀꢀꢀCl(4i) [3.068 Å; symmetry
code (i) ꢁx, 1 ꢁ y, ꢁz] that associates the molecules into dimers
in the crystal lattice (Fig. 9).
pared as described in the literature [16]. The ligand
L is
reported in the literature [4,5], but it has been obtained by a
new synthetic route.
3. Conclusion
4.2. Synthesis of 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol (L)
A new easily one-step synthetic route with 96% yield of hybrid
ligand 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol (L) is presented.
Also, three new complexes with transition metals containing L
are reported. The noticeable different coordination capability of L
and the geometry imposed by the metallic centre lead to a diver-
sity of structures and characteristics for each compound. In
[PdCl2(L)2] (1), the metallic centre has the preference to be coordi-
A solution of 1,3-diphenylpropan-1,3-dione (8.92 mmol, 2.00 g)
and 2-hydroxiethylhydrazine (11.56 mmol, 0.88 g) in dry toluene
(50 mL) in a Dean-Stark apparatus during 12 h. The resulting solu-
tion is evaporated to dryness obtaining a white crystalline solid
that corresponds to
L
(2.26 g, 8.56 mmol, 96%). Calc. for
nated to two ligands L via j
1-N generating an ideal square planar
C
17H16N2O: C, 77.25; H, 6.10; N, 10.60. Found: C, 77.20; H, 6.09;
N, 10.94%.
m
m
max(KBr)/cmꢁ1 3241
(C–H)al, 1548 m(C@C/C@N)ar, 1483–1438 d(C@C/C@N)ar, 1076
m(JY), 3015 m(C–H)ar, 2950–2846
geometry. Also, the ligand disposition permits to build hydrogen
bonds creating a 1-D chain. The interaction is observed in solid
and solution. Complex [ZnCl2(L)] (2) presents ligand L connected
d(C–H)ip, 810, 765 d(C–H)oop; dH (250 MHz; CDCl3 at 298 K; Me4Si)
to Zn(II) via
j
2-N,O building a six-membered metallocycle ring
7.80–7.70 (m, 2H, orto-C6H5), 7.54–7.20 (m, 8H, C6H5), 6.56 (s, 1H,
3
pz-CH), 4.20 (t, JHH = 5.0 Hz, 2H, pz-CH2CH2-OH), 3.96 (t,
with a distorted boat conformation and distorted tetrahedral
geometry. Although a large quantity of structures are collected in
the literature, the distance Zn–OH presents higher values than
the values described in the literature. Finally, [CuCl(L0)]2 (3) pre-
sents a dinuclear compound where one of the Cu(II) atom is con-
3JHH = 5.0 Hz, 2H, pz-CH2CH2–OH); dC (63 MHz; CDCl3 at 298 K;
Me4Si) 151.4, 146.1 (pzC-Ph), 133.3, 130.6 (pz-CPh), 129.9–125.9
(C6H5), 103.7 (pz-CH), 62.5 (pz-CH2CH2–OH), 51.3 (pz-CH2CH2–
OH); m/z (ESI+) 265 (37%, [LH]+), 233 (100, [L-CH2OH]+), 219 (79,
[L-CH2CH2OH]+).
nected via
j
2-N,O to two ligands in a head-to-head arrangement
generating two metallocycles of six members with a distorted boat
conformation. Each ligand has lost its alcohol group proton and the
oxygen connects stronger to metallic centres. Also, magnetic stud-
ies reveal 3 is an antiferromagnetic compound and EPR implies 3
does not retain its dinuclear structure in the solvent, but decom-
poses to one or more mononuclear species, in contrast with com-
4.3. Synthesis of the complexes
4.3.1. Synthesis of [PdCl2(L)2] (1)
A solution of L (2.00 mmol, 0.529 g) dissolved in dichlorometh-
ane (10 mL) was added to
a solution of [PdCl2(CH3CN)2]

S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
217
Table 3
Crystallographic data for L, 1, 2 and 3.
L
1
2
3
Formula
C
17H16N2O
C34H32Cl2N4O2Pd
C17H16Cl2N2OZn
C34H30Cl2N4O2Cu2ꢀ1.15
CH3NO2
Formula weight
Temperature (K)
Wavelength (Å)
System, space group
Unit cell dimensions
a (Å)
264.32
150(2)
0.71073
705.96
293(2)
0.71073
400.61
293(2)
0.71073
orthorhombic, P212121
794.82
150(2)
0.71073
monoclinic, P21/c
ꢀ
ꢀ
triclinic, P1
triclinic, P1
10.5557(1)
11.603(5)
7.748(3)
14.0637(11)
b (Å)
12.2791(2)
11.679(4)
13.492(5)
12.2620(10)
c (Å)
22.0690(3)
13.443(5)
16.156(4)
21.8142(16)
a
(°)
b (°)
(°)
85.0305(6)
76.3817(6)
89.6723(8)
2769.28(6)
87.09(2)
88.52(3)
61.24(2)
1594.9(11)
90.00
90.00
90.00
1688.9(10)
90.00
98.824(3)
90.00
3717.3(5)
c
V (Å
3
)
Z
8
2
4
4
Dcalc (g cmꢁ3
)
1.268
0.080
1120
1.470
0.786
720
1.575
1.775
816
1.420
1.332
1627
l
(mmꢁ1
F(0 0 0)
)
Crystal size (mm3)
Crystal colour
hkl ranges
0.36 ꢃ 0.30 ꢃ 0.22
0.2 ꢃ 0.1 ꢃ 0.1
0.2 ꢃ 0.1 ꢃ 0.1
0.16 ꢃ 0.15 ꢃ 0.03
colourless
orange
colourless
green
ꢁ13 6 h 6 13, ꢁ15 6 k 6 15,
ꢁ28 6 l 6 28
1.84–27.48
ꢁ16 6 h 6 16, ꢁ16 6 k 6 16,
ꢁ18 6 l 6 18
ꢁ10 6 h 6 10, ꢁ18 6 k 6 16,
ꢁ22 6 l 6 22
ꢁ18 6 h 6 18, ꢁ16 6 k 6 16,
ꢁ29 6 l 6 29
2h range (°)
1.52–30.00
2.92–29.99
2.21–28.52
Reflections collected/unique/
59 193/12 649
[R(int) = 0.0996]
99.8
16 405/8410 [R(int) = 0.0347]
16 505/4799 [R(int) = 0.0455]
85 535/9190 [R(int) = 0.0495]
[Rint
]
Completeness to h (%)
90.3
98.0
97.3
Absorption correction
multi-scan
none
none
multi-scan
Data/restrains/Parameters
12 649/0/734
1.004
8410/0/470
1.188
4799/0/212
1.246
9190/30/474
1.078
Goodness-of-fit (GOF) on F2
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0480, wR2 = 0.1129
R1 = 0.0868, wR2 = 0.1305
0.235 and ꢁ0.242
R1 = 0.0503, wR2 = 0.0966
R1 = 0.0636, wR2 = 0.1031
0.909 and ꢁ0.947
R1 = 0.0515, wR2 = 0.1344
R1 = 0.0574, wR2 = 0.1454
0.841 and ꢁ1.107
R1 = 0.0380, wR2 = 0.1054
R1 = 0.0497, wR2 = 0.1114
1.062 and ꢁ0.352
Largest difference in peak and
hole (e Åꢁ3
)
(1.00 mmol, 0.259 g) in dichloromethane (15 mL). The mixture was
stirred during 12 h and the solution was concentrated to 5 mL and
precipitated with 10 mL of cold diethyl ether obtaining an orange
crystalline powder that corresponds to 1 (0.80 mmol, 0.565 g,
80%). Calc. for C34H32N4O2Cl2Pd: C, 57.84; H, 4.57; N, 7.94. Found:
(pzC-Ph), 133.5, 130.8 (pz-CPh), 129.6–125.5 (C6H5), 103.6 (pz-
CH), 61.1 (pz-CH2CH2–OH), 51.5 (pz-CH2CH2–OH); m/z (ESI+) 363
(100%, [ZnClL]+).
4.3.3. Synthesis of [CuCl(L0)]2 (3)
C, 58.09; H, 4.41; N, 7.81%. Conductivity
(
X
ꢁ1 cm2 molꢁ1
max(KBr)/cmꢁ1 3497
(OH), 3060
(C–H)ar, 2944, 2884 m(C–H)al, 1554 m(C@C/C@N)ar, 1482–1447
;
1.00 ꢃ 10ꢁ3 M in acetone) 4;
m
m
A solution of L (1.00 mmol, 0.264 g) dissolved in nitromethane
(10 mL) was added to a solution of CuCl2 (1.00 mmol, 0.134 g) dis-
solved in nitromethane (15 mL). The mixture was stirred during
12 h and the solution was concentrated to dryness and a green so-
lid was obtained. The solid is redissolved in 5 mL of nitromethane
and 50 mL of diethyl ether were added slowly. After 24 h green
prismatic crystals were obtained corresponding to 3 (0.80 mmol,
0.298 g, 11%); Calc. for C34H30N4O2Cl2Cu2ꢀ1.15CH3NO2: C, 53.12;
m
d(C@C/C@N)ar, 1074 d(C–H)ip, 761, 698 d(C–H)oop; dH (250 MHz;
CDCl3 at 298 K; Me4Si) 8.12–8.04 (m, 4H, orto-C6H5), 7.59–7.34
3
(m, 16H, C6H5), 6.34 (s, 2H, pz-CH), 4.73 (t, JHH = 11.9 Hz, 4H, pz-
CH2CH2–OH), 3.93 (m, 4H, pz-CH2CH2–OH), 2.07 (m, 2H,
CH2CH2–OH); dC (63 MHz; CDCl3 at 298 K; Me4Si) 155.1, 150.4
(pzC-Ph), 133.1 (pz-CPh), 130.8–128.8 (C6H5), 109.3 (pz-CH), 59.7
(pz-CH2CH2–OH), 52.1 (pz-CH2CH2–OH); m/z (ESI+) 671 (100%;
[PdCl(L)2]+), 633 (85%, [Pd(L)2–H]+).
H, 4.24; N, 9.08. Found: C, 53.35; H, 4.15; N, 8.75 %.
mmax(KBr)/
cmꢁ1 3059
m
(C–H)ar, 2924, 2846 (C–H)al, 1550 (C@C/C@N)ar,
m
m
1481–1451 d(C@C/C@N)ar, 1075 d(C–H)ip, 763, 698 d(C–H)oop; m/
z (ESI+) 691 (4%, [Cu2ClL2]+), 591 (100, [CuL2]+).
4.3.2. Synthesis of [ZnCl2(L)] (2)
A solution of L (1.00 mmol, 0.264 g) dissolved in absolute etha-
nol (10 mL) was added to a solution of ZnCl2 (1.00 mmol, 0.146 g)
dissolved in absolute ethanol (15 mL). Also, 3 mL of triethylortho-
formiate were added to the previous solution and the mixture was
stirred during 12 h. The solution was evaporated to dryness and
the white powder obtained was washed with cold diethyl ether
leading to 2 (0.30 mmol, 0.120 g, 94%). Calc. for C17H16N2OCl2Zn:
C, 50.97; H, 4.03; N, 6.99. Found: C, 50.79; H, 4.05; N, 7.25%. Con-
4.4. X-ray crystal structures of L and 1–3
Suitable prismatic crystals for X-ray diffraction of L (colourless)
and 1 (orange), 2 (colourless) and 3 (green) were obtained by slow
evaporation of the following solutions: nitromethane (L), chloro-
form (1), methanol:diethyl ether (2) and nitromethane:diethyl
ether (3).
Diffraction data for L and 3 were measured using Bruker X8
Apex diffractometer, with graphite-monochromated Mo Ka radia-
ductivity
(X
ꢁ1 cm2 molꢁ1
;
1.03 ꢃ 10ꢁ3
M
in acetonitrile) 12;
(C–H)al,
m
max(KBr)/cmꢁ1 3446
m
(O–H), 3060
m
(C–H)ar, 2931, 2861
m
1551
m
(C@C/C@N)ar, 1481–1453 d(C@C/C@N)ar, 1077 d(C–H)ip,
tion generated by a rotating anode and was fitted with an Oxford
Cryostream low temperature device. Diffraction data for 1 and 2
were measured on a MAR 345 diffractometer with an image plate
detector and intensities were collected with graphite monochro-
763, 698 d(C–H)oop; dH (250 MHz; CD3OD at 298 K; Me4Si) 7.76–
7.67 (m, 2H, orto-C6H5), 7.52–7.17 (m, 8H, C6H5), 6.58 (s, 1H, pz-
CH), 4.15 (t, JHH = 11.5 Hz, 2H, pz-CH2CH2–OH), 3.87 (m, 2H, pz-
3
CH2CH2–OH); dC (63 MHz; CD3OD at 298 K; Me4Si) 151.5, 146.8
matized Mo Ka radiation.

218
S. Muñoz et al. / Inorganica Chimica Acta 373 (2011) 211–218
(c) C. Pettinari, R. Pettinari, Coord. Chem. Rev. 249 (2005) 663;
Unit-cell parameters were determined from 59 193 (L), 217 (1),
(d) A.L. Gavrilova, B. Bosnich, Chem. Rev. 104 (2004) 349;
(e) V.V. Grushin, Chem. Rev. 104 (2004) 1629;
(f) P. Braunstein, J. Organomet. Chem. 689 (2004) 3953;
(g) R.W. Date, E.F. Iglesias, K.E. Rowe, J.M. Elliott, D.W. Bruce, Dalton Trans.
(2003) 1914;
(h) X. Morise, P. Braunstein, R. Welter, Inorg. Chem. 42 (2003) 7752;
(h) C.J. Elsevier, J. Reedijk, P.H. Walton, M.D. Ward, Dalton Trans. (2003) 1869–
1880.;
(i) N. Robertson, L. Cronin, Coord. Chem. Rev. 227 (2002) 93;
(j) R. Mukherjee, Coord. Chem. Rev. 203 (2000) 151;
(k) E. Lindler, T. Schneller, F. Auer, H.A. Mayer, Angew. Chem., Int. Ed. 38 (1999)
2155;
4197 (2) and 85 535 (3) reflections [2 < h < 28 (L), 3 < h < 31 (1),
3 < h < 30 (2) and 2 < h < 29 (3)] and refined by least-squares
method.
For L, 59 193 reflections were measured in the range
1.84 < h < 27.48 and 12 649 of them were non-equivalent by sym-
metry [Rint (on I) = 0.0996]. Eight thousand one hundred and five
reflections were assumed as observed applying the condition
I > 2r (I). Lorentz-polarisation and multi-scan absorption correc-
tions were made.
For 1, 16 405 reflections were measured in the range
1.52 < h < 30.00 and 8410 of them were non-equivalent by symme-
try [Rint (on I) = 0.0347]. Eight thousand four hundred and ten
reflections were assumed as observed applying the condition
(l) G. La Monica, G.A. Ardizzoia, Prog. Inorg. Chem. 46 (1997) 151;
(m) S. Trofimenko, Prog. Inorg. Chem. 34 (1986) 115;
(n) S. Trofimenko, Chem. Rev. 72 (1972) 497.
[2] (a) G. Aragay, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-Bardia,
J. Ros, Aust. J. Chem. 63 (2010) 257;
(b) M. Guerrero, J. Pons, T. Parella, M. Font-Bardia, T. Calvet, J. Ros, Inorg. Chem.
48 (2009) 8736;
I > 2
made.
r(I). Lorentz-polarisation but no absorption corrections were
(c) M. Guerrero, J. Pons, V. Branchadell, T. Parella, X. Solans, M. Font-Bardia, J.
Ros, Inorg. Chem. 47 (2008) 11084;
(d) G. Aragay, J. Pons, J. García-Antón, X. Solans, M. Font-Bardia, J. Ros, J.
Organomet. Chem. 693 (2008) 3396;
For 2, 16 505 reflections were measured in the range
2.92 < h < 29.99 and 4799 of them were non-equivalent by symme-
try [Rint (on I) = 0.0455]. Four thousand five hundred and forty five
(e) S. Muñoz, J. Pons, X. Solans, M. Font-Bardia, J. Ros, J. Organomet. Chem. 693
(2008) 2132;
(f) M. Espinal, J. Pons, J. García-Antón, X. Solans, M. Font-Bardia, J. Ros, Inorg.
Chim. Acta 361 (2008) 2648;
reflections were assumed as observed applying the condition I > 2
r
(I). Lorentz-polarisation but no absorption corrections were made.
For 3, 85 535 reflections were measured in the range
2.21 < h < 28.52 and 9190 of them were non-equivalent by symme-
try [Rint (on I) = 0.0495]. Seven thousand five hundred and seventy
seven reflections were assumed as observed applying the condition
(g) A. de León, J. Pons, J. García-Antón, X. Solans, M. Font-Bardia, J. Ros, Inorg.
Chim. Acta 360 (2007) 2071;
(h) A. Panella, J. Pons, J. García-Antón, X. Solans, M. Font-Bardia, J. Ros, Eur. J.
Inorg. Chem. (2006) 1678.
[3] (a) M. Guerrero, J. Pons, M. Font-Bardia, T. Calvet, J. Ros, Aust. J. Chem. 63
(2010) 958;
I > 2
r (I). Lorentz-polarisation and multi-scan absorption correc-
(b) V. Montoya, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-
Bardia, J. Ros, Organometallics 27 (2008) 1084;
tions were made.
The structures of L, 1–3 were solved by direct methods, using
SHELXS-97 computer program [17] and refined by full-matrix least-
squares method with SHELXL-97 computer program [18], using
59 193 (L), 16 405 (1), 16 505 (2) and 85 535 (3) reflections. The
(c) V. Montoya, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-
Bardia, J. Ros, J. Fluorine Chem. 128 (2007) 1007;
(d) V. Montoya, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-
Bardia, J. Ros, Organometallics 26 (2007) 3183;
(e) V. Montoya, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-
Bardia, J. Ros, Inorg. Chim. Acta 360 (2007) 625;
(f) A. Boixassa, J. Pons, X. Solans, M. Font-Bardia, J. Ros, Inorg. Chim. Acta 357
(2004) 733–738.;
function minimised was
R
w||FO|2 ꢁ |FC|2|2, where w = [
r
2(I) +
(0.0691P)2]ꢁ1 (L), w = [
r
2(I) + (0.0200P)2 + 2.0772P]ꢁ1 (1), w =
[r r
2(I) + (0.0709)2 + 1.3269P]ꢁ1 (2) and w = [ 2(I) + (0.0515P)2 +
(g) A. Boixassa, J. Pons, X. Solans, M. Font-Bardia, J. Ros, Inorg. Chim. Acta 355
(2003) 254;
(h) J. García-Antón, J. Pons, X. Solans, M. Font-Bardia, J. Ros, Eur. J. Inorg. Chem.
(2003) 2992;
(i) A. Boixassa, J. Pons, A. Virgili, X. Solans, M. Font-Bardia, J. Ros, Inorg. Chim.
Acta 340 (2002) 49.
4.9940P]ꢁ1 (3). For the four crystalline structures P = (|FO|2 + 2
|FC|2)/3.
All hydrogen atoms were computed using a riding model, ex-
cept the O-bound H atoms in L, which were located in the Fourier
map and allowed to refine freely with a refined common Uiso ther-
mal parameter of 0.069(3) Å2. The refined O–H distances in that
structure range from 0.90(2)–0.93(2) Å. The rest of the parameters
refined and other details concerning the refinement of the crystal
structures are gathered in Table 3.
[4] (a) F. Bondavelli, O. Bruno, A. Ranise, P. Schenone, D. Donnoli, M. Cenicola, C.
Matera, S. Russo, E. Marmo, Farmaco 44 (1989) 655;
(b) F. Bondavalli, O. Bruno, A. Ranise, P. Schenone, P. Addonizio, V. DeNovellis,
A. Loffreda, E. Marmo, Farmaco, Edizione Scientifica 43 (1988) 725.
[5] Hai-Ling Liu, Huan-Feng Jiang, Min Zhang, Wen-Juan Yao, Quin Hua Zhu, Zhon
Tang, Tetrahedron Lett. 49 (2008) 3805.
[6] D.H. Williams, I. Fleming, Spectroscopic Methods in Organic Chemistry,
McGrawHill, London, UK, 1995.
[7] F.H. Allen, Acta Crystallogr., Sect. B 58 (2002) 380.
[8] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
Supplementary material
[9] D.H. Williams, I. Fleming, Spectroscopic Methods in Organic Chemistry,
McGrau-Hill, London, UK, 1995;
Crystallographic data for the structural analysis has been depos-
ited with the Cambridge Crystallographic Data Centre, CCDC refer-
ence number 794898 for compound L, 794899 for compound 1,
794900 for compound 2 and 794901 for compound 3. Copies of this
information may be obtained free of charge from The Director,
E. Pretch, T. Clerc, J. Seibl, W. Simon, Tables of Determination of Organic
Compounds. 13C NMR, 1H NMR IR, MS, UV/Vis, Chemical Laboratory Practice,
Springer, Berlin, Germany, 1989.
[10] (a) A.R. Katritzky, C.W. Rees, Comprehensive Heterocyclic Chemistry: The
Structure, Reactions, Synthesis, Uses of Heterocyclic Compounds, Pergamon
Press, Oxford, UK, 1984;
CCDC, 12 Union Road, Cambridge, CB2 1EZ. UK: fax:
+ 44
(b) D. Carmona, L.A. Oro, M.P. Lamala, J. Elguero, M.C. Apreda, C. Foces-Foces,
F.H. Cano, Angew. Chem., Int. Ed. Engl. 25 (1986) 1114.
[11] C.J. O’Connor, Prog. Inorg. Chem. 29 (1982) 203.
[12] L. Merz, W. Haase, J. Chem. Soc., Dalton Trans. (1980) 875.
[13] B.A. Goodman, J.B. Raynor, Adv. Inorg. Chem. 13 (1970) 135.
[14] (a) Z. You, W. Liu, H. Zhu, Transition. Met. Chem. 39 (2004) 653;
(b) C.A. Bear, J.M. Waters, T.N. Waters, J. Chem. Soc., Dalton Trans. (1974) 1059;
(c) E. Sinn, W.T. Robinson, J. Chem. Soc., Chem. Commun. 6 (1972) 359.
[15] SIGMAPLOT, Program for Tabulating, Modelling and Displaying Data (v. 8.02), SPSS
Inc., Chicago IL, USA, 2002.
[16] S. Komiya, in: Synthesis of Organometallic Compounds: A Practice Guide, Ed.
Board, New York, USA, 1997.
[17] G.M. Sheldrick, SHELXS-97, Program for Crystal Structure Determination,
University of Göttingen, Germany, 1997.
[18] G.M. Sheldrick, SHELXL-97, Program for Crystal Structure Refinement, University
of Göttingen, Germany, 1997.
1223336033; e-mail: diposit@ccdc.cam.acuk or www.htpp://
ccdc.cam.ac.uk.
Acknowledgements
Support by the Spanish Ministerio de Educacion y Cultura (pro-
jecte CTQ2007-63913 BQU) and the UK Engineering and Physical
Sciences Research Council is gratefully acknowledged. In memory
of Prof. Xavier Solans i Huguet
References
[1] (a) M.A. Halcrow, Dalton Trans. (2009) 2059;
(b) C. Pettinari, R. Pettinari, Coord. Chem. Rev. 249 (2005) 525;