Synthesis, characterization and X-ray crystal structure determination of cyclopalladated [Csp2,N,N′]-, zwitterionic and chelated compounds in the reaction of 3,5-diphenyl-N-alkylaminopyrazole derived ligands with Pd(II)

Article abstract of DOI:10.1016/j.jorganchem.2008.07.038

The synthesis of two N-alkylaminopyrazole ligands, 1-[2-(diethylamino)ethyl]-3,5-diphenylpyrazole (L1) and 1-[2-(dioctylamino)ethyl]-3,5-diphenylpyrazole (L2), is reported. These ligands present, a priori, one pyrazole nitrogen and one amine nitrogen as potential donor atoms. However, in the reaction of the ligands (L1 and L2) with [PdCl₂(CH₃CN)₂] one of the C_phenyl atoms can also behave as a donor atom. As a result, we have obtained the formation of three different compounds for each one of the ligands: chelated ([PdCl₂(L)] L = L1 (1a), L2 (2a)), zwitterionic ([PdCl₃(LH)] LH = LH1 (1b), LH2 (2b)), and cyclopalladated compounds ([PdCl(LC)] (LC = LC1 (1c), LC2 (2c)). The solid-state structures for 1a, 1b and 1c were determined by single crystal X-ray diffraction methods. The potentially [C,N,N′]^- ligand is coordinated through the N_pz and the N_amino to the metal atom for 1a, through the N_pz for 1b, and through the N_pz, the N_amino and a C_phenyl for 1c.

Full text of DOI:10.1016/j.jorganchem.2008.07.038

Journal of Organometallic Chemistry 693 (2008) 3396–3404
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, characterizationꢀand X-ray crystal structure determination of
cyclopalladated [Csp2,N,N0] , zwitterionic and chelated compounds in the
reaction of 3,5-diphenyl-N-alkylaminopyrazole derived ligands with Pd(II)
a
Gemma Aragay a, Josefina Pons a, , Jordi García-Antón , Xavier Solans b,1, Mercè Font-Bardia b, Josep Ros a,
*
*
a Departament de Química, Unitat de Química Inorgànica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
b Cristal.lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 July 2008
Received in revised form 24 July 2008
Accepted 28 July 2008
Available online 5 August 2008
The synthesis of two N-alkylaminopyrazole ligands, 1-[2-(diethylamino)ethyl]-3,5-diphenylpyrazole (L1)
and 1-[2-(dioctylamino)ethyl]-3,5-diphenylpyrazole (L2), is reported. These ligands present, a priori, one
pyrazole nitrogen and one amine nitrogen as potential donor atoms. However, in the reaction of the
ligands (L1 and L2) with [PdCl2(CH3CN)2] one of the Cphenyl atoms can also behave as a donor atom. As
a result, we have obtained the formation of three different compounds for each one of the ligands: che-
lated ([PdCl2(L)] L = L1 (1a), L2 (2a)), zwitterionic ([PdCl3(LH)] LH = LH1 (1b), LH2 (2b)), and cyclopalla-
dated compounds ([PdCl(LC)] (LC = LC1 (1c), LC2 (2c)). The solid-state structures fꢀor 1a, 1b and 1c
were determined by single crystal X-ray diffraction methods. The potentially [C,N,N0] ligand is coordi-
nated through the Npz and the Namino to the metal atom for 1a, through the Npz for 1b, and through
the Npz, the Namino and a Cphenyl for 1c.
Keywords:
Cyclopalladated
Zwitterionic
Chelates
N-alkylaminopyrazole ligands
Crystal structures
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
thesized with phenyl and pyridyl groups in positions 3 and 5 of the
pyrazole ring: 2-(1-ethyl-5-phenyl-1H-pyrazol-3-yl)pyridine and
Cyclometallated compounds have been widely studied over the
last three decades [1], and have acquired great interest because of
the applications of metallacycles in many areas including organic
synthesis [2], catalysis [3] and material science [4], and as biolog-
ically active compounds [5].
2-(1-octyl-5-phenyl-1H-pyrazol-3-yl)pyridine. Their reactivity
with Pd(II) and Pt(II) has also been studied, yielding cis-[MCl2(L)]
complexes [12]. The allylpalladium complexes of these ligands
have also been obtained [13]. Some of these pyridylpyrazole palla-
dium complexes have been tested as catalysts in the Heck reaction
giving rise to highly efficient catalytic results [14].
Moreover, we have described the synthesis of ligands contain-
ing a phenyl and a methyl group in positions 3 and 5 of the pyra-
zole ring (1-ethyl-5-methyl-3-phenyl-1H-pyrazole and 5-methyl-
1-octyl-3-phenyl-1H-pyrazole) and we have studied their reactiv-
ity with [PdCl2(CH3CN)2] and K2PtCl4, resulting in trans-[MCl2(L)2]
complexes [15].
Palladium compounds containing at least one metal–carbon
bond intramolecularly stabilized by at least one donor atom,
termed cyclopalladated compounds or palladacycles, are one of
the most popular classes of cyclometallated compounds [6].
A wide variety of palladacycles containing a
r
(Pd–Csp2) or a
r
(Pd–Csp3) bond from a bidentate [C,X]ꢀ {X = N,P,O,S} or a triden-
tate [C,X,Y]ꢀ or [X,C,Y]ꢀ {X,Y = N,P,O,S} ligand, including palladacy-
cles containing heterocyclic system, have been described so far [7].
In particular, studies of tridentate intramolecular coordination
systems [N,C,N]ꢀ have become one of the central themes in the
development of organometallic chemistry [8]. Besides that, cyclo-
palladated non-symmetrical compounds containing a [Csp2,N,N]ꢀ
chelating ligand with mixed five- and six-membered rings are
not common [9].
In this paper, we present the synthesis and characterization of
two 3,5-diphenyl-N-alkylaminopyrazole ligands containing
a
dialkylaminoethyl group at the N1 position, 1-[2-(diethylamino)-
ethyl]-3,5-diphenylpyrazole (L1) and 1-[2-(dioctylamino)ethyl]-
3,5-diphenylpyrazole (L2), and the study of their reactivity with
Pd(II). The ligands make use of one pyrazole nitrogen, one amine
nitrogen, and/or one Cphenyl as donor atoms (Scheme 1).
Our group has previously reported the synthesis of 3,5-di-
methyl-N-alkylaminopyrazole ligands, and studied their reactivity
with Pd(II), Pt(II) [10] and Rh(I) [11]. Other ligands have been syn-
2. Results and discussion
2.1. Synthesis of the ligands
* Corresponding authors. Fax: +34 93 581 31 01 (J. Pons).
E-mail address: Josefina.Pons@uab.es (J. Pons).
Deceased September 3, 2007.
Although 1-[2-(diethylamino)ethyl]-3,5-diphenylpyrazole (L1)
has already been described in the literature [16], a modified
1
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.07.038

G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
3397
[PdCl2(CH3CN)2]
N
N
N
Cl
Cl
N
N
CH2Cl2, 24 h
Pd
R
R = Et; L1
R = Oct; L2
N
R = Et; 1a
R = Oct; 2a
R
R
R
[PdCl2(CH3CN)2]
CH2Cl2, 72 h
Method A: Method B:
[PdCl2(CH3CN)2] [PdCl2(CH3CN)2]
Et3N CH3CN (reflux), 24 h
CH2Cl2, 24 h
CH2Cl2, 48 h
R = Et; 1b
R = Oct; 2b
N
N
Cl
Cl
-
Pd
R
H
+
N
N
R
N
Cl
Pd
R
Cl
N
+
R
R = Et; 1c
R = Oct; 2c
N
N
R = Et; 1c
R = Oct; 2c
Pd
Cl
N
R
R
Scheme 1.
pathway for its synthesis is presented here. This new method is
also useful to develop a new ligand that had not been previously
described: 1-[2-(dioctylamino)ethyl]-3,5-diphenylpyrazole (L2).
The synthesis of the two ligands consists of the treatment of 1-
(2-toluene-p-sulfonyloxyethyl)-3,5-diphenylpyrazole [17] with
the appropriate secondary amine (L1: diethylamine; L2: dioctyl-
amine) in the presence of sodium hydroxide in a mixture of tetra-
hydrofuran and water (L1, 4:1; L2, 7:3). Each product is obtained as
yellow oil. L2 ligand is further purified by chromatography (silica
gel 60 Å) with ethyl acetate as the eluent.
cationic ligand. The most interesting products of these reactions
are complexes 1c and 2c which are cyclopalladated species. These
metallated compounds can be easily separated from zwitterionic
derivatives (1b and 2b, respectively) due to their high solubility
in dichloromethane. Therefore, zwitterionic compounds are iso-
lated by precipitation from the reaction medium (1b) or forcing
the precipitation with dry and cool diethyl ether (2b). The filtered
solutions contain compounds with Pd–C bond (1c and 2c, respec-
tively) (Scheme 1).
In the literature, cyclopalladation reactions are known to pro-
ceed through a wide variety of mechanisms such as C–H activation,
oxidative addition, transmetallation or nucleophilic addition onto
an unsaturated bond [1a,6]. In general, cyclopalladation of aro-
matic derivates complexes is considered to occur by a simple elec-
trophilic aromatic substitution pathway [20].
Ligands were characterized by elemental analyses, mass spec-
trometry and IR, 1H and 13C{1H} NMR spectroscopies. The NMR sig-
nals were assigned by reference to the literature [18] and from
DEPT, COSY and HMQC NMR experiments.
2.2. Synthesis and characterisation of the complexes
Most of palladium assisted palladation of C–H bonds include
chloropalladium compounds with a base or acetate derivatives that
act as proton acceptors. In our case, the reaction works because the
amino group of a chelated complex acts as a phenyl proton accep-
tor leading to zwitterionic compounds 1b and 2b and to cyclomet-
allated 1c and 2c, respectively, so no extra base is needed.
In order to improve the yield of the cyclometallated compounds
described in this paper, different experiments were performed. On
one hand, reactions at higher temperature (reflux in dry acetoni-
trile for 24 h) were carried out. In this study, the cyclometallated
compound is the only species obtained with a yield of 42% for 1c
and 46% for 2c. On the other hand, reactions with additional trieth-
ylamine base with ligands L1 and L2 were also performed in dry
dichloromethane. In both cases, chloro salts precipitated and met-
allated 1c and 2c compounds were formed in a shorter time. No
zwitterionic complexes were detected during the reaction. These
Complexes [PdCl2(L)] (L = L1 (1a), L2 (2a)) were obtained by
treatment of the corresponding ligand with [PdCl2(CH3CN)2] [19]
in a 1:1 or 1:2 M/L ratio in dry dichloromethane for 24 h. If this
reaction is continued for 72 h at room temperature, compounds
1a and 2a practically disappear, leading to the formation of com-
pounds [PdCl3(L1H)] 1b, [PdCl(L1C)] 1c (1b/1c, 1:1) and
[PdCl3(L2H)] 2b, [PdCl(L2C)] 2c (2b/2c, 1:1), respectively (Scheme
1). 1H NMR controls were performed to follow the reaction evolu-
tion. L1H and L2H correspond to L1 and L2 ligands, respectively,
with the amine group protonated; L1C and L2C correspond to L1
and L2 ligands, respectively, with a carbon atom deprotonated in
an ortho position of one phenyl group.
Complexes 1a and 2a have a chelated N,N0 ligand, whereas com-
plexes 1b and 2b are zwitterionic species with a Npz-coordinated

3398
G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
results suggest that the presence of a proton acceptor is indeed
needed in the formation of these metallated complexes and com-
plexes 1a and 2a or bases such as triethylamine can play this role.
Several techniques were used for the characterization of all
complexes: elemental analyses, mass spectrometry, conductivity
measurements, IR, 1H and 13C{1H} NMR spectroscopies and X-ray
diffraction, when possible.
The elemental analyses for complexes 1a and 2a are consistent
with the formula [PdCl2(L)] (L = L1, L2), for 1b and 2b with
[PdCl3(LH)] (LH = L1H, L2H) and for 1c and 2c with [PdCl(LC)]
(LC = L1C, L2C). The positive ionization spectra MSꢀ(ESI+) of com-
pounds 1a, 1b, and 1c give a peak with a m/z value of 424.1 (100%)
attributable to (Pd(L1C)+), and for 2a, 2b, and 2c a peak at 592.3
(100%), attributable to (Pd(L2C)+) is observed.
band corresponding to
and two bands for
(Pd–Cl) between 335–330 and 326–319 cmꢀ1
which are typical of compounds with a cis disposition of the chloro
m
(Pd–N) at 449 and 441 cmꢀ1, respectively,
m
,
ligands around the Pd(II) [22]. For complexes 1b and 2b, only two
bands were assigned, one for
tively, and another one for
m
(Pd–N) at 411 and 444 cmꢀ1, respec-
m
(Pd–Cl) at 335 and 340 cmꢀ1, respec-
tively [22]. For complexes 1c and 2c, one band was observed for
m
m
(Pd–N) at 418 and 417 cmꢀ1, respectively, and one band for
(Pd–Cl) at 279 cmꢀ1 for both complexes [23].
The 1H, 13C{1H}NMR, DEPT, COSY, HMQC, and NOESY spectra
were recorded in CDCl3 for 1a, 1c, 2a, and 2c, and in CD3CN for
1b and 2b due to the poor solubility of these complexes in CDCl3
and other solvents.
The 1H NMR spectra of complexes 1a and 2a at room tempera-
ture show the ethylene protons of the Npz–CH2–CH2–Namino chain
as two poorly defined broad signals. This behaviour implies that
a dynamic process is taking place in solution at this temperature.
For this reason, we recorded variable temperature spectra (233–
298 K) (Fig. 1).
Conductivity values in acetonitrile for all complexes are in
agreement with the presence of non-electrolyte compounds (6.7–
84.0
In the IR spectra of 1b and 2b, some distinguished signals ap-
X
ꢀ1 cm2 molꢀ1) [21].
pear corresponding to the protonated amino group, m
(N–H+) and
d(N–H+) (2695, 1613 cmꢀ1 for 1b and 2693, 1624 cmꢀ1 for 2b)
[18]. The IR spectra for all complexes in the region 600–100 cmꢀ1
were also studied. Complexes 1a and 2a show one well-defined
Lowering of the temperature provokes a progressive splitting of
the two signals corresponding to each CH2. At 233 K, four well-de-
fined bands are observed at d = 5.25, 4.48, 3.76 and 3.17 ppm for 1a
10
16
11
17
9
15
4
6
12
3
5
14
8
13
7
H
18b
N
N
H
1
2
19b
18aH
N
20
H
19a
298 K
H18
H19
253 K
H18a
H19a
H19b
H18b
233 K
273 K
H18a
H18b
H19a
H19b
H19a
H19b
H18a
H18b
5.2
5.0
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
(ppm)
Fig. 1. 1H NMR spectra (250 MHz) of complex 1a in CDCl3 at various temperatures (233–298 K) and numbering scheme for all the compounds.

G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
3399
Table 1
and at d = 5.23, 4.51, 3.79 and 3.14 ppm for 1b. The fluxional pro-
cess takes place with
D
Gà values of ca. 57 kJ molꢀ1 for 1a and ca.
Selected bond lengths (Å) and bond angles (°) for 1a, 1b ꢁ 1/4CH2Cl2 ꢁ 1/4CH3CN and
1c
58 kJ molꢀ1 for 2a, as deduced from the coalescence behaviour of
the ethylene resonances [24]. These values are consistent with
other data described in the literature attributable to the ring-flip-
ping of six-membered rings [11b,25].
1a
Pd–N(1)
Pd–N(3)
N(1)–Pd–N(3)
N(1)–Pd–Cl(2)
N(3)–Pd–Cl(2)
1b
2.037(5)
2.114(6)
90.3(2)
171.95(15)
91.92(17)
Pd–Cl(2)
Pd–Cl(1)
N(1)–Pd–Cl(1)
N(3)–Pd–Cl(1)
Cl(2)–Pd–Cl(1)
2.2935(18)
2.301(2)
88.96(15)
170.26(15)
90.19(7)
In the 1H NMR spectra of 1b and 2b, protons H18 of the Npz
–
CH2–CH2–Namino chain can be assigned as
d = 4.49 ppm for 1b and at d = 4.54 ppm for 2b. On the other hand,
protons corresponding to H19 appear as quadruplet at
a
triplet at
Molecule A
Molecule B
Pd(2)–N(21)
Pd(2)–Cl(22)
Pd(2)–Cl(21)
a
Pd(1)–N(11)
Pd(1)–Cl(12)
Pd(1)–Cl(11)
Pd(1)–Cl(13)
N(11)–Pd(1)–Cl(12)
N(11)–Pd(1)–Cl(11)
Cl(12)–Pd(1)–Cl(11)
N(11)–Pd(1)–Cl(13)
Cl(12)–Pd(1)–Cl(13)
Cl(11)–Pd(1)–Cl(13)
1c
Pd–N(1)
Pd–N(3)
N(1)–Pd–C(1)
N(1)–Pd–N(3)
C(1)–Pd–N(3)
2.033(4)
2.037(4)
d = 3.58 ppm for 1b and at d = 3.61 ppm for 2b (H19 protons are
coupled with H18 protons and the hydrogen of the amino moiety
with similar coupling constants) (numbering from Fig. 1). More-
over, a broad band can be observed at d = 8.65 ppm for 1b and
d = 9.05 ppm for 2b, attributable to the protonated amine nitrogen
(N–H+) (H20).
2.2967(16)
2.3035(15)
2.3083(15)
89.74(12)
87.99(12)
177.25(5)
179.51(12)
90.73(6)
2.3208(16)
2.3007(16)
2.2771(14)
89.59(13)
89.74(13)
178.24(5)
178.72(11)
89.61(6)
Pd(2)–Cl(23)
N(21)–Pd(2)–Cl(22)
N(21)–Pd(2)–Cl(21)
Cl(21)–Pd(2)–Cl(22)
N(21)–Pd(2)–Cl(23)
Cl(23)–Pd(2)–Cl(22)
Cl(23)–Pd(2)–Cl(21)
No significant differences between 13C{1H} NMR spectra for free
and coordinated ligands were observed for complexes 1a, 1b, 2a
and 2b.
91.55(6)
91.03(6)
1.977(3)
2.207(4)
80.06(17)
90.77(14)
168.84(16)
Pd–C(1)
Pd–Cl
N(1)–Pd–Cl
C(1)–Pd–Cl
N(3)–Pd–Cl
2.014(5)
Finally, the 1H NMR spectra for complexes 1c and 2c have also
been studied. The CH2 protons of the Npz–CH2–CH2–Namino chain
2.3108(16)
174.58(11)
95.80(14)
93.72(10)
appear as two sharp signals at d = 4.30 ppm (H18
)
)
and
and
d = 3.13 ppm (H19 for 1c and at d = 4.28 ppm (H18
)
d = 3.15 ppm (H19) for 2c (numbering from Fig. 1). The signals that
appear at d = 7.93 ppm for 1c and at d = 7.92 ppm for 2c, which
integrate only one proton, are attributable to H11 (numbering from
Fig. 1). This observation is consistent with the ortho-palladation of
the 3-phenyl ring. In the 13C{1H} NMR spectra for compounds 1c
and 2c, the signals corresponding to the terminal chain and the
phenyl carbons, except C–Pd, do not show significant differences
compared to the same signals in the free ligands. The signal for
C–Pd of these complexes appears at lower fields (d = 136.8 ppm
for 1c and d = 145.2 ppm for 2c) compared to the same signals
for the free ligands (d = 129.5–126.0 ppm). The signal for pyrazolic
carbon C–H is observed at d = 101.2 ppm for 1c and 2c and for the
free ligands it appears at d = 103.7 ppm. These values are also con-
sistent with the ortho-palladation of the 3-phenyl ring [9,26].
with a tetrahedral distortion. This distortion can be observed in the
mean separation (0.018(3) Å) of the atoms coordinated to the Pd
atom. The environment consists of two chlorine atoms in cis dispo-
sition and one ligand coordinated via one Npz and one Namino to the
Pd(II). Selected bond lengths and angles data are gathered in
Table 1. Ligand L1 acts as a bidentated chelate, forming a six-
membered metallacycle ring, with twist boat conformation.
The PdCl2(Npz)(N) core (containing terminal chlorine atoms) is
found in the literature as part of 43 crystal structures [27], but only
two of them contain an aliphatic amine [10a,b]. The Pd–Namino
bond length (2.114(6) Å) is clearly longer than Pd–Npz bond length
(2.037(5) Å), and also longer than those reported for other struc-
tures described in the literature with the same environment,
[PdCl2(NN0)] (NN0 = 1-[2-(ethylamino)ethyl]-3,5-dimethylpyrazole
and 1-[2-(tert-butylamino)ethyl]-3,5-dimethylpyrazole, whose
Pd–Namino distances are 2.061(5) and 2.097(4) Å, respectively
2.3. Crystal and molecular structure of [PdCl2(L1)] (1a)
Compound 1a consists of monomeric cis-[PdCl2(L1)] molecules
(Fig. 2). The palladium centre has a typical square-planar geometry
[10a,b]. Both distances, (Pd–Namino and Pd–Npz), are consistent
with previously described values for Pd–Namino (2.017–2.280 Å)
[10a,b,28], and for Pd–Npz (1.979–2.141 Å) bonds [15,25b,29].
The Pd–Cl bond lengths (2.301(2), 2.2935(18) Å) can also be re-
garded as normal compared with distances found in the literature
(2.280–2.341 Å) [10a,b,15,25b,29a–g]. The value of N–Pd–N bite
angle is 90.3(2)°. Moreover, the Cl–Pd–Cl angle is 90.19(7)°, show-
ing the small deviation from the square-planar geometry. The bite
angle is slightly bigger than those found in the literature for com-
plexes [PdCl2(NN0)] (NN0 = 1-[2-(ethylamino)ethyl]-3,5-dimethyl-
pyrazole and 1-[2-(tert-butylamino)ethyl]-3,5-dimethylpyrazole),
89.3(2)° and 88.16(18)°, respectively [10a,b].
2.4. Crystal and molecular structure of [PdCl3(L1H)] ꢁ 1/4CH2Cl2 ꢁ
1/4CH3CN (1b ꢁ 1/4CH2Cl2 ꢁ 1/4CH3CN)
Compound 1b ꢁ 1/4CH2Cl2 ꢁ 1/4CH3CN consists of two molecules
(A and B) of [Pd2+(L1H)+(Clꢀ)3] (Fig. 3), and solvent molecules. In
each molecule, the palladium ion is surrounded by one pyrazole
nitrogen and three chlorine atoms in a distorted square-planar
geometry (with a tetrahedral distortion, where the metallic atom
lies 0.014 Å (molecule A) and 0.026 Å (molecule B) out of the coor-
dination plane). Selected bond lengths and angles data are gath-
ered in Table 1.
Fig. 2. ORTEP drawing of complex 1a, showing all non-hydrogen atoms and the
atom numbering scheme; 50% probability amplitude displacement ellipsoids are
shown.

3400
G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
Fig. 4. ORTEP drawing of complex 1c, showing all non-hydrogen atoms and the
atom numbering scheme; 50% probability amplitude displacement ellipsoids are
shown.
between N(13)–H(13)N and Cl(13) are 2.34 Å for Hꢁ ꢁ ꢁCl(13),
3.231(5) Å for N(13)ꢁ ꢁ ꢁCl(13) and 164° for N(13)–Hꢁ ꢁ ꢁCl(13). The
symmetry code for molecule A is 1/2 ꢀ x, 1/2 + y, 1 ꢀ z. In molecule
B the N(23)–H bond length has been geometrically fixed in the
refinement (0.91 Å) and the contact parameters between N(23)–
H(23)N and Cl(22) are 2.32 Å for Hꢁ ꢁ ꢁCl(22), 3.184(4) Å for
N(13)ꢁ ꢁ ꢁCl(22) and 158° for N(23)–Hꢁ ꢁ ꢁCl(22). The symmetry code
for molecule B is 1/2 ꢀ x, 1/2 + y, ꢀz.
2.5. Crystal and molecular structure of [PdCl(L1C)] (1c)
The crystal structure of 1c consists of monomeric [PdCl(L1C)]
molecules (Fig. 4). The palladium centre is coordinated to L1 ligand
by three atoms (one nitrogen atom of the pyrazolyl group, one
nitrogen atom of the amine moiety and one deprotonated carbon
of the phenyl group), along with one chlorine atom in a slightly dis-
torted square-planar geometry. The tetrahedral distortion can be
observed from the bond angles and from the mean separation
(0.025 Å) of the atoms coordinated to the Pd atom in relation to
the mean plane that contains these four atoms and the Pd atom.
The dihedral angle between the planes N(3)–Pd–Cl and N(1)–Pd–
Cl is 12.13(17)°. In this structure, L1 ligand acts as a tridentated
chelate and forms a six-membered ring and a five-membered ring,
with an envelope conformation for Pd–N(1)–N(2)–C(16)–C(17)–
N(3) and a plane conformation for Pd–C(1)–C(6)–C(7)–N(1), which
share an edge (Pd–Npz). Some selected bond lengths and bond an-
gles for this complex are listed in Table 1.
The PdClC(Npz)(N) core is present in five complexes previously
described in the literature [8a–c,32]. Three of them present a Pd–
C bond forming a cyclopalladated compound. Two of these com-
pounds are [N,Csp2, N] [8a,b] and the other one is [N,Csp3,N] [8c].
The Pd–Npz (1.977(3) Å), the Pd–Namino (2.207(4) Å), the Pd–Cl
(2.3108(16) Å), and the Pd–C bond length (2.014(5) Å) can be re-
garded as normal compared to the distances found in the litera-
ture. The Pd–C and Pd–N bond distances are consistent with
those reported for aꢀwide variety of palladacycles holding [C,N]ꢀ,
[C,N,N]ꢀ or [C,N,N0] ligands [27]. For Pd–Cl, the literature de-
scribed values between 2.280 and 2.341 Å [8b,10a,b,15,29a–g].
Fig. 3. ORTEP drawing of the two different molecules of complex 1b, showing all
non-hydrogen atoms and the atom numbering scheme; 50% probability amplitude
displacement ellipsoids are shown.
The Pd–N and Pd–Cl bond lengths are normal compared to the
values described in the literature. These values lay between 1.979–
2.141 Å for Pd–Npz [15,25b,29] and 2.280–2.341 Å for Pd–Cl
[10a,b,15,25b,29a–g]. The N–Pd–Cl and Cl–Pd–Cl bond angles
slightly deviate from the square-planar angles. The Namino atom
(N(13), molecule A; N(23), molecule B) is protonated. Only one
structure with PdCl3(Npz) core (containing terminal chlorine
atoms) had been previously described in the literature. This com-
pound is [PdCl3L0] (L0 = 1-[2-(3,5-dimethylpyrazol-1-yl)ethyl]-3-
(4-fluorobenzyl)-3H-imidazol-1-ium) [30]. Two other zwitterionic
structures with pyrazolic derived ligands have been found in the
literature, ([MCl3(L00)]: M = Cu(II), L00 = 2-(3,5-dimethyl-1-pyrazol-
yl)ethylamine [31]; M = Ni(II) , L00 = 1-10-(dithiodiethylene)-bis-
(3,5-dimethylpyrazole) [29e]).
In molecules A and B, the Namino–H proton (N(13) (A), N(23) (B))
is intermolecularly hydrogen bridged to a chlorine atom (Cl(13)
(A), Cl(22) (B)), from another molecule, linking the molecules into
a chain. In molecule A, the N(13)–H bond length has been geomet-
rically fixed in the refinement (0.91 Å) and the contact parameters
3. Conclusions
The reaction of 3,5-diphenyl-N-alkylaminopyrazole ligands, L1
and L2, with [PdCl2(CH3CN)2] yields three different compounds for

G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
3401
each ligand, in one pot but two steps reaction. The reaction begins
with the formation of a N,N0 chelated compound (1a and 2a) as it
happens with other N-alkylamine ligands reported in our group.
Pd–Namino bond lengths of compounds 1a and 2a are longer than
the ones that have already been reported [10a,b]. The rearrange-
ment of the chelated compounds produces two different new spe-
cies in a 1:1 ratio, zwitterionic compounds (1b and 2b) and
cyclopalladated compounds (1c and 2c). In zwitterionic complexes,
the ligand is coordinated through the Npz and displays the amino
group in the protonated form, and Pd(II) is bonded to three chloro li-
gands that confer a formal negative charge to the metal centre. On
the other hand, in cyclometallated compounds 1c and 2c, the metal
centre is coordinated through the Npz, the Namino and a Cphenyl. It con-
sists of a non-symmetrical [Csp2,N,N0]ꢀ pincer-type palladacycle.
The simultaneous formation of zwitterionic and metallated prod-
ucts is explained by the need of acid acceptor molecules (complexes
1a and 2a) in the reaction medium. They act as bases that capture the
aromatic proton and that are the driving force towards the cyclopal-
ladation reaction. The method we report here is a simple pathway to
obtain cyclopalladated compounds in mild conditions.
fractions containing L2 pure were gathered and the solvent was re-
moved under vacuum. After evaporation pale-yellow oil was ob-
tained. (Yield: L1, 47% (0.54 g); L2, 43% (0.75 g)).
L1: Anal. Calc. for C21H25N3 (319.2): C, 78.96; H, 7.89; N, 13.15.
Found: C, 78.73; H, 7.61; N, 12.95%. mmax (NaCl)/cmꢀ1 3040
m
(C–
(C@N)pz
1460, 1432 d(C@C)ar, d(C@N)ar, 1070 d(C–H)ip, 761, 693 d(C–H)oop ar
H)ar, 2971–2806
m
(C–H)al, 1602
m
(C@C)ph, 1547
m
(C@C)pz
,
m
,
.
1H NMR (250 MHz, CDCl3; 298 K): 7.78 (d, 2H, 3J = 8.1 Hz, H7, H11),
7.39 (m, 8H, H8–10 , H13–17), 6.49 (s, 1H, H4), 4.14 (t, 2H, 3J = 7.2 Hz,
H18), 3.37 (q, 4H, 3J = 7.1 Hz, Namino(CH2CH3)2), 2.82 (t, 2H,
3J = 7.2 Hz, H19), 0.82 (t, 6H, 3J = 7.1 Hz, Namino(CH2CH3)2) ppm.
13C NMR (63 MHz, CDCl3; 298 K): 151.0, 145.7, 134.1, 131.4 (C3,
C5, C6, C12), 129.5–126.0 (C7–11, C13–17), 103.7 (C4), 53.4 (C19), 48.7
(C18), 48.0 (Namino(CH2CH3)2), 12.3 (Namino(CH2CH3)2) ppm. m/z
(ESI+) 342.1 (MNa+) (33%), 326.1 (MLi+) (100%), 320.1 (MH+) (88%).
L2: Anal. Calc. for C33H49N3 (487.4): C, 81.26; H, 10.13; N, 8.61.
Found: C, 80.99; H, 9.84; N, 8.59%.
2925–2854 (C–H)al, 1607 (C@C)ph, 1549
1485, 1462 d(C@C)ar, d(C@N)ar, 760, 693 d(C–H)oop
m
max (NaCl)/cmꢀ1 3061
m
(C–H)ar,
(C@N)pz
1H NMR
m
m
m
(C@C)pz
,
m
,
.
ar
(250 MHz, CDCl3; 298 K): 7.89 (d, 2H, 3J = 7.2 Hz, H7, H11), 7.44
(m, 8H, H8–10, H13–17), 6.61 (s, 1H, H4), 4.25 (t, 2H, 3J = 7.1 Hz,
H18), 2.91 (t, 2H, 3J = 7.1 Hz, H19), 2.35 (t, 4H, 3J = 7.0 Hz,
Namino(CH2(CH2)6CH3)2), 1.26 (br, 24H, Namino(CH2(CH2)6CH3)2),
0.93 (t, 6H, 3J = 7.0 Hz, Namino(CH2(CH2)6CH3)2) ppm. 13C NMR
(63 MHz, CDCl3; 298 K): 151.0, 145.6, 134.1, 131.4 (C3, C5, C6,
4. Experimental
4.1. General details
C12), 129.5–126.0 (C7–11, C13–17), 103.7 (C4), 55.2 (C18), 54.4
All reagents were commercial grade materials and were used
without further purification. The reactions were carried out under
nitrogen using vacuum-line and Schlenk techniques. Solvents were
dried and distilled according to standard procedures and stored
under nitrogen. Elemental analyses (C, H, N) were carried out by
the staff of the Chemical Analyses Service of Universitat Autònoma
de Barcelona on an EuroVector 3011 instrument. Conductivity
(Namino(CH2(CH2)6CH3)2), 48.7 (C19), 32.3–23.1 (Namino(CH2(CH2)6-
CH3)2), 14.5 (Namino(CH2(CH2)6CH3)2) ppm. m/z (ESI+) 488.4 (MH+)
(100%).
4.3. Synthesis of the complexes [PdCl2(L)] (L = L1 (1a), L = L2 (2a)),
[PdCl3LH] (LH = L1H (1b), L = L2H (2b)), [PdCl(LC)] (LC = L1C (1c),
L = L2C (2c))
measurements were performed at room temperature in 10ꢀ3
M
acetonitrile solutions employing a CyberScan CON 500 (Euthech
Instruments) conductimeter. Infrared spectra were run on a Per-
kin–Elmer FT spectrophotometer, series 2000 cmꢀ1 as NaCl disks,
4.3.1. Synthesis of complexes 1a and 2a
A solution of 0.27 mmols of the corresponding ligand (L1
(0.086 g); L2 (0.130 g)) dissolved in 10 mL of dry dichloromethane
was added to a solution of 0.27 mmols (0.070 g) of [PdCl2(CH3CN)2]
in 10 mL of the same solvent. The solution was stirred for 24 h at
room temperature. The resultant solution was concentrated to
5 mL under vacuum and 3 mL of cool and dry diethyl ether was
added to induce precipitation. The resulting precipitate (1a and
2a, respectively) was filtered and washed twice with 3 mL of cool
and dry diethyl ether, and dried under vacuum. The ratio 1 M:2 L
has also been tested, and showed the same results. (Yield: 1a,
48% (0.064 g); 2a, 55% (0.098%)).
KBr pellets or polyethylene films in the range 4000–100 cmꢀ1
.
1H, 13C{1H}, DEPT, COSY, HMQC, and NOESY NMR spectra were re-
corded with a NMR-FT Bruker 250 MHz spectrometer in CDCl3 or
CD3CN solutions at room temperature. All chemical shift values
(d) are given in ppm. Mass spectra (ESI+) were obtained with an Es-
quire 3000 ion-trap mass spectrometer from Bruker Daltonics in
methanol. The complex [PdCl2(CH3CN)2] was synthesized accord-
ing to published methods [19]. The precursor 1-(2-toluene-p-sulfo-
nyloxyethyl)-3,5-diphenylpyrazole was prepared as described in
the literature [17].
4.3.2. Synthesis of complexes 1b, 2b and 1c, 2c
4.2. Synthesis of the ligands 1-[2-(diethylamino)ethyl]-3,5-
diphenylpyrazole (L1) and 1-[2-(dioctylamino)ethyl]-3,5-
diphenylpyrazole (L2)
A solution of 0.27 mmols of the corresponding ligand (L1
(0.086 g); L2 (0.130 g)) dissolved in 10 mL of dry dichloromethane
was added to a solution of 0.27 mmol (0.070 g) of [PdCl2(CH3CN)2]
in 10 mL of the same solvent. The solution was stirred at room
temperature for 72 h and 1H NMR controls were made every
24 h. Controls show the evolution of three species on the reaction.
As the reaction progresses, the molar ratios 1b:1a, 1c:1a and 2b:2a
and 2c:2a increase. For the reaction with the ligand L1 a precipitate
appeared in the solutions (1b), and for the reaction with the ligand
L2 the precipitation of 2b was induced by adding 5 mL of cool and
dry diethyl ether to the solution. Solids were filtered off and
washed three times with 5 mL of dry dichloromethane and dried
under vacuum. The resultant solutions were reduced to 5 mL,
and 3 mL of cool and dry diethyl ether was added to induce the
precipitation of a brown solid. The resulting precipitate (1c/2c)
was filtered and washed twice with 3 mL of cool and dry diethyl
The synthesis consists of the reaction between 1-(2-toluene-p-
sulfonyloxyethyl)-3,5-diphenylpyrazole
(1.50 g,
3.58 mmol),
23.6 mmol of the appropriate secondary amine (L1: diethylamine
99% , 2.5 mL; L2: dioctylamine 97%, 7.3 mL), and sodium hydroxide
(98%, 0.85 g, 20.8 mmol). The reaction was carried out in a 20 mL
solution of tetrahydrofuran:water (L1: 4:1; L2: 7:3) with continu-
ous stirring at reflux for 48 h. The mixture was then cooled down
to room temperature and extracted three times with 10 mL of chlo-
roform. The organic phase was collected and dried overnight with
anhydrous Na2SO4. The solution was filtered off and the solvent
was removed under vacuum. L1 ligand was obtained as pure
pale-yellow oil. L2 ligand was obtained as yellow oil that consists
of a mixture of L2 and initial secondary amine. In order to purify
L2, a silica gel column with ethyl acetate as eluent was used. The

3402
G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
ether and dried under vacuum. (Yield: 1b, 39% (0.059 g), 1c, 30%
(0.037 g); 2b, 45% (0.085 g), 2c 23% (0.039 g)).
3J = 7.1 Hz, H11), 7.46, 7.01 (m, 8H, H8–10, H13–17), 6.49 (s, 1H, H4),
4.30 (m, 2H, H18), 3.46 (m, 2H, Namino(CH2CH3)2), 3.13 (m, 2H,
H19), 3.01 (m, 2H, Namino(CH2CH3)2), 1.32 (t, 6H, 3J = 7.1 Hz,
4.3.3. Alternative synthesis of complexes 1c and 2c
N
amino(CH2CH3)2) ppm. 13C NMR (63 MHz, CDCl3; 298 K): 159.4,
(a) A solution of 0.27 mmols of the corresponding ligand (L1
(0.086 g); L2 (0.130 g)) dissolved in 10 mL of dry acetonitrile was
added to a solution of 0.27 mmol (0.070 g) of [PdCl2(CH3CN)2] in
10 mL of the same solvent. The solution is left under reflux for
24 h giving rise to the carbopalladated species. The solution was
reduced to 5 mL, and 3 mL of cool and dry diethyl ether was added
to induce the precipitation of 1c and 2c, respectively. Solids were
washed twice with 3 mL of cool and dry diethyl ether and dried un-
der vacuum. (Yield: 1c, 42% (0.052 g), 2c, 46% (0.078 g)).
(b) A solution of 0.27 mmols of the corresponding ligand (L1
(0.086 g); L2 (0.130 g)) dissolved in 10 mL of dry dichloromethane
was added to a solution of 0.27 mmol (0.070 g) of [PdCl2(CH3CN)2]
in 10 mL of the same solvent. 0.27 mmol of triethylamine (99%,
0.028 g) was added to the solution and almost immediately a white
solid corresponding to Et3HNCl appeared. The solution was filtered
and stirred at room temperature for 24 h. 1H NMR controls show
the evolution of two species on the reaction. As the reaction pro-
gresses the molar ratio 1c/2c:1a/2a (carbopalladated com-
pounds:chelated compounds) increases. The solution was
reduced to 5 mL, and 3 mL of cool and dry diethyl ether was added
to induce the precipitation of some impurities. The resulting fil-
tered solutions containing 1c and 2c, respectively, were reduced
to 5 mL and 5 mL of dry diethyl ether were added to induce precip-
itation of 1c/2c. Solids were washed twice with 3 mL of cool and
dry diethyl ether and dried under vacuum. (Yield: 1c, 50%
(0.062 g), 2c, 49% (0.083 g)).
148.6, 145.2, 137.5 (C3, C5, C6, C12), 136.8 (C7), 129.9–122.2 (C8–11,
C13–17), 101.2 (C4), 50.9 (Namino(CH2CH3)2), 50.7 (C19), 44.8 (C18),
10.4 (Namino(CH2CH3)2) ppm. m/z (ESI+) 424.1 (Pd(L1C)+) (100%).
2a: Anal. Calc. for C33H49Cl2N3Pd (663.2): C, 59.59; H, 7.43; N,
6.32. Found: C, 59.71; H, 7.41; N, 6.56%.
X
ꢀ1 cm2 molꢀ1
(9.8 ꢂ 10ꢀ4 M in acetonitrile) 11.4. mmax (KBr)/cmꢀ1 3048
m(C–H)ar,
2924, 2853
m(C–H)al, 1605
m
(C@C)ph, 1552
m
(C@C)pz
,
m
(C@N)pz,
1480, 1467, 1453 d(C@C)ar, d(C@N)ar, 1019 d(C–H)ip, 762, 693
mmax (polyethylene)/cmꢀ1 441
d(C–H)oop (Pd–N), 330, 319
m
(Pd–Cl). 1H NMR (250 MHz, CDCl3; 298 K): 8.33 (d, 2H,
.
ar
m
3J = 7.6 Hz, H7, H11), 7.33 (m, 8H, H8–10 , H13–17), 6.61 (s, 1H, H4),
4.86 (br, 2H, H18), 3.51 (br, 2H, H19), 2.63 (br, 4H, Nami-
no(CH2(CH2)6CH3)2), 1.27 (br, 24H, Namino(CH2(CH2)6CH3)2), 0.88
(t, 6H, 3J = 7.0 Hz, Namino(CH2(CH2)6CH3)2) ppm. 13C NMR
(63 MHz, CDCl3; 298 K): 156.9, 147.8, 131.3, 130.4 (C3, C5, C6,
C12), 129.6–125.4 (C7–11, C13–17), 107.7 (C4), 58.4 (C19), 49.9 (Nami-
no(CH2(CH2)6CH3)2), 31.9 (C18), 31.7–21.6 (Namino(CH2(CH2)6CH3)2),
14.2 (Namino(CH2(CH2)6CH3)2) ppm. m/z (ESI+) 592.3 (Pd(L2C)+)
(100%).
2b: Anal. Calc. for C33H50Cl3N3Pd (699.2): C, 56.50; H, 7.18; N,
5.99. Found: C, 56.71; H, 7.28; N, 6.06%.
X
ꢀ1 cm2 molꢀ1
(1.2 ꢂ 10ꢀ3 M in acetonitrile) 68.2. mmax (KBr)/cmꢀ1 3114–3040
m
(C–H)ar, 2984–2855
m
(C–H)al, 2693
m
,
(N–H+), 1624 d(N–H+),1609
1451 d(C@C)ar, d(C@N)ar,
m(C@C)ph
,
1553
m(C@C)pz
,
m
(C@N)pz
1076 d(C–H)ip, 759, 696 d(C–H)oop
444
.
mmax (polyethylene)/cmꢀ1
ar
m
(Pd–N), 340
m
(Pd–Cl). 1H NMR (250 MHz, CD3CN; 298 K):
1a: Anal. Calc. for C21H25Cl2N3Pd (495.0): C, 50.77; H, 5.07; N,
9.05 (br, 1H, H20), 7.89 (d, 2H, 3J = 7.2 Hz, H7, H11), 7.58 (m, 8H,
H8–10, H13–17), 6.89 (s, 1H, H4), 4.54 (t, 2H, 3J = 4.4 Hz, H18), 3.61
(q, 2H, 3J = 4.4 Hz, H19), 3.23 (br, 8H, Namino((CH2)2(CH2)5CH3)2),
1.30 (br, 20H, Namino((CH2)2(CH2)5CH3)2), 0.89 (t, 6H, 3J = 7.2 Hz,
8.46. Found: C, 50.83; H, 5.32; N, 8.17%.
X
ꢀ1 cm2 molꢀ1
(1.1 ꢂ 10ꢀ3 M in acetonitrile) 7.5. mmax (KBr)/cmꢀ1 3058
m
(C–H)ar,
2959–2853
m(C–H)al, 1620
m(C@C)ph, 1547
m
(C@C)pz
,
m
(C@N)pz,
1476, 1469, 1447 d(C@C)ar, d(C@N)ar, 1004 d(C–H)ip, 760, 695
d(C–H)oop (Pd–N), 335, 326
mmax (polyethylene)/cmꢀ1 449
(Pd–Cl). 1H NMR (250 MHz, CDCl3; 298 K): 8.31 (d, 2H,
N
amino(CH2(CH2)6CH3)2) ppm. 13C NMR (63 MHz, CD3CN; 298 K):
.
m
155.6, 148.3, 131.4, 130.7 (C3, C5, C6, C12), 130.0–128.9 (C7–11,
ar
m
C13–17), 108.9 (C4), 54.2 (Namino(CH2(CH2)6CH3)2), 52.8 (C19), 45.3
(C18), 32.1, 23.0 (Namino(CH2(CH2)6CH3)2), 14.5 (Namino(CH2(CH2)6-
CH3)2) ppm. m/z (ESI+) 592.3 (Pd(L2C)+) (100%).
3J = 7.1 Hz, H7, H11), 7.53 (m, 8H, H8–10, H13–17), 6.81 (s, 1H, H4),
4.87 (br, 2H, H18), 3.42 (br, 2H, H19), 2.87 (m, 2H, Namino(CH2CH3)2),
2.65 (br, 2H, Namino(CH2CH3)2), 1.57 (br, 6H, Namino(CH2CH3)2) ppm.
13C NMR (63 MHz, CDCl3; 298 K): 156.6, 148.6, 132.7, 130.5 (C3, C5,
C6, C12), 129.5–125.7 (C7–11, C13–17), 107.5 (C4), 56.5 (C18), 50.6 (C19),
47.6 (Namino(CH2CH3)2), 12.2 (Namino(CH2CH3)2) ppm. m/z (ESI+)
424.1 (Pd(L1C)+) (100%).
2c: Anal. Calc. for C33H48ClN3Pd (627.3): C, 63.05; H, 7.70; N,
6.68. Found: C, 62.73; H, 7.61; N, 6.57%.
X
ꢀ1 cm2 molꢀ1
(1.1 ꢂ 10ꢀ3 M in acetonitrile) 19.5. mmax (KBr)/cmꢀ1 3108–3054
m(C–H)ar, 2956–2853 m(C–H)al, 1587, 1540 m(C@C)ph, 1511
m
(C@C)pz
,
m
(C@N)pz, 1465, 1454, 1421 d(C@C)ar, d(C@N)ar, 1025
1b: Anal. Calc. for
(564.7): C, 46.29; H, 4.86; N, 8.06. Found: C, 46.58; H, 4.84; N,
C
21H26Cl3N3Pd ꢁ 1/4CH2Cl2 ꢁ 1/4 CH3CN
d(C–H)ip, 759, 689 d(C–H)oop
.
ar
mmax (polyethylene)/cmꢀ1 417
m(Pd–N), 279 m
(Pd–Cl). 1H NMR (250 MHz, CDCl3; 298 K): 7.92
8.05%.
X
ꢀ1 cm2 molꢀ1 (1.0 ꢂ 10ꢀ3 M in acetonitrile) 84.0. mmax
(1H, m, H11), 7.33 (8H, m, H8–10, H13–17), 6.49 (1H, s, H4), 4.28
(2H, m, H18), 3.33 (2H, m, Namino(CH2(CH2)6CH3)2), 3.15 (2H, m,
H19), 2.62 (2H, m, Namino(CH2(CH2)6CH3)2), 1.25 (24H, br, Namino-
(KBr)/cmꢀ1 3114
m(C–H)ar, 2983–2849 m(C–H)al, 2695 m
(N–H+),
1613 d(N–H+), 1587
1462, 1443 d(C@C)ar, d(C@N)ar, 1378 d(CH3), 1016 d(C–H)ip, 771,
698 d(C–H)oop (Pd–N), 335
mmax (polyethylene)/cmꢀ1 411
m
(C@C)ph, 1554
m
(C@C)pz
,
m
(C@N)pz, 1482,
(CH2(CH2)6CH3)2), 0.87 (6H, t, 3J = 7.0 Hz, Namino(CH2(CH2)6CH3)2)
ppm. 13C NMR (63 MHz, CDCl3; 298 K): 159.5, 148.6, 137.5, 136.9
(C3, C5, C6, C12), 145.2 (C7), 130.0–122.2 (C8–11, C13–17), 101.2 (C4),
57.6 (Namino(CH2(CH2)6CH3)2), 51.9 (C19), 45.0 (C18), 31.9–22.8
(Namino(CH2(CH2)6CH3)2), 10.4 (Namino(CH2(CH2)6CH3)2) ppm. m/z
(ESI+) 592.3 (Pd(L2C)+) (100%).
.
m
ar
m
(Pd–Cl). 1H NMR (250 MHz, CD3CN; 298 K): 8.65 (br, 1H, H20),
7.87 (d, 2H, 3J = 7.6 Hz, H7, H11), 7.55 (m, 8H, H8–10, H13–17), 6.86
(s, 1H, H4), 4.49 (t, 2H, 3J = 4.7 Hz, H18), 3.58 (q, 2H, 3J = 4.7 Hz,
H19), 3.34 (m, 4H, Namino(CH2CH3)2), 1.32 (t, 6H, 3J = 7.0 Hz,
N
amino(CH2CH3)2) ppm. 13C NMR (63 MHz, CD3CN; 298 K): 129.8–
126.0 (C3, C5–11, C12–17), 104.3 (C4), 52.5 (Namino(CH2CH3)2), 48.2
(C18), 30.3 (C19), 8.8 (Namino(CH2CH3)2) ppm. m/z (ESI+) 424.1
(Pd(L1C)+) (100%).
4.4. X-ray crystal structure analyses of complexes 1a, 1b ꢁ 1/
4CH2Cl2 ꢁ 1/4CH3CN and 1c
1c: Anal. Calc. for C21H24ClN3Pd (459.1): C, 54.79; H, 5.26; N,
Suitable crystals for X-ray diffraction of compounds 1a, 1b and
1c were obtained through crystallization from a dichloromethane/
diethyl ether (2:1) mixture.
For compound 1a, a prismatic crystal was selected and mounted
on an Enraf-Nonius CAD4 four-circle diffractometer. Unit-cell
parameters were determined from automatic centring of 25 reflec-
tions (12 < h < 21°) and refined by least-squares method. For com-
9.13. Found: C, 54.62; H, 5.55; N, 9.09%.
X
ꢀ1 cm2 molꢀ1
(1.4 ꢂ 10ꢀ3 M in acetonitrile) 6.7. mmax (KBr)/cmꢀ1 3114–3040
m
m
(C–H)ar, 2959–2853
m
(C–H)al, 1580, 1539
m
(C@C)ph
,
1506
(C@C)pz
724, 695 d(C–H)oop ar
,
m
(C@N)pz, 1451 d(C@C)ar, d(C@N)ar, 1015 d(C–H)ip, 761,
mmax (polyethylene)/cmꢀ1 418
(Pd–N), 279
(Pd–Cl). 1H NMR (250 MHz, CDCl3; 298 K): 7.93 (d, 1H,
.
m
m

G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
3403
pounds 1b ꢁ 1/4CH2Cl2 ꢁ 1/4CH3CN and 1c, a prismatic crystal was
selected and mounted on a MAR 345 diffractometer with an image
plate detector. Unit-cell parameters were determined from 2594
reflections for 1b and 2167 reflections for 1c (3 < h < 31°) and re-
fined by least-squares method.
Intensities were collected with graphite monochromatized Mo
Ka radiation, using x/2h scan-technique. For 1a, 13118 reflections
fined, using a riding model, with an isotropic temperature factor
equal to 1.2 times the equivalent temperature factor of the atom
which is linked. For 1b, all H atoms were computed and refined
with an overall isotropic temperature.
The final R(F) factor and Rw(F2) values as well as the number of
parameters refined and other details concerning the refinement of
the crystal structure are gathered in Table 2.
were measured in the range 2.24 6 h 6 29.99 and 6193 of which
were non-equivalent by symmetry (Rint(on I) = 0.037). Reflections
Supplementary material
(2250) were assumed as observed applying the condition I P 2
r
(I). Three reflections were measured every two hours as orientation
and intensity control, significant intensity decay was not observed.
For 1b, 59442 reflections were measured in the range 2.63 6
h 6 30.00 and 15023 reflections of which were non-equivalent by
symmetry (Rint(on I) = 0.098). Reflections (10116) were assumed
CCDC 675557, 675558 and 675559 contains the supplementary
crystallographic data for 1a, 1b and 1c. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
as observed applying the condition I > 2r (I). For 1c, 34736 reflec-
tions were measured in the range 2.83 6 h 6 30.00 and 5649 of
which were non-equivalent by symmetry (Rint(on I) = 0.055).
Reflections (5627) were assumed as observed applying the condi-
Acknowledgements
In memory of Dr. Xavier Solans Huguet. The Support by the
Spanish Ministerio de Educación y Cultura (project CTQ2007
63913/BQU) is gratefully acknowledged.
tion I P 2r (I). Lorentz-polarization but no absorption corrections
were made.
The structures were solved by direct methods, using SHELXS com-
puter program (SHELXS-97) [33] and refined by full matrix least-
squares method with SHELXL-97 [34] computer program using
13118 reflections for 1a, 59442 reflections for 1b and 34736
References
[1] (a) A.D. Ryabov, Chem. Rev. (1990) 403–424;
reflections for 1c (very negative intensities were not assumed).
(b) E.C. Constable, D.G.F. Rees, Polyhedron 17 (1998) 3281–3289;
(c) I. Omae, Coord. Chem. Rev. 248 (2004) 995–1023;
(d) I. Omae, J. Organomet. Chem. 692 (2007) 2608–2632;
(e) K. Godula, D. Sames, Science 312 (2006) 67–72.
[2] (a) A.D. Ryabov, Synthesis 3 (1985) 233–252;
P
2
2
The function minimized was
wjjF2O ꢀ jFCj j , where for 1a w =
[
r
2(I) + 0.0432P]2]ꢀ1 , for 1b w = [
r
2(I) + (0.0907P)2 + 0.5167P]ꢀ1
and for 1c w = [
r
2(I) + 5.4658P]ꢀ1 and P = (|FO|2 + 2|FC|2)/3 for all
(b) M. Pfeffer, Recl. Trav. Chim. Pay-Bas 109 (1990) 567–576;
(c) M. Pfeffer, Pure Appl. Chem. 64 (1992) 335–342;
(d) J. Spencer, M. Pfeffer, Adv. Met. Org. Chem. 6 (1998) 103–144;
(e) V.V. Dunina, O.N. Gorunova, Russ. Chem. Rev. 73 (2004) 309–350.
[3] (a) W.A. Herrmann, V.P.W. Bohm, C.P. Reisinger, J. Organomet. Chem. 576
(1999) 23–41;
the structures. For 1a and 1c, all H atoms were computed and re-
Table 2
Crystallographic data for 1a, 1b ꢁ 1/4 CH2Cl2 ꢁ 1/4 CH3CN and 1c
1a
1b
1c
(b) R.B. Bedford, C.S.J. Cazin, D. Holder, Coord. Chem. Rev 248 (2004) 2283–
2321;
(c) F. Bellina, A. Carpita, R. Rossi, Synthesis 15 (2004) 2419–2440;
(d) I.P. Beletskaya, A.V. Cheprakov, J. Organomet. Chem. 689 (2004) 4055–
4082.
Formula
C21H25Cl2N3Pd C87H109N13Cl14Pd4 C21H24N3ClPd
Formula weight
496.74
293(2)
0.71073
Orthorhombic Monoclinic
Pbca
2258.77
293(2)
0.71073
460.28
293(2)
0.71073
Orthorhombic
Pbca
Temperature (K)
0
Wavelength (AÅ)
System, space group
[4] J. Buey, P. Espinet, J. Organomet. Chem. 507 (1996) 137–145.
[5] K.K. Lo, C. Chung, T.K. Lee, L. Lui, K.H. Tang, N. Zhu, Inorg. Chem. 42 (2003)
6886–6897.
[6] (a) J. Dupont, C.S. Consorti, J. Spencer, Chem. Rev. 105 (2005) 2527–2571;
(b) I. Favier, M. Gómez, J. Granell, M. Martínez, X. Solans, M. Font-Bardía,
Dalton Trans. (2005) 123–132.
[7] (a) S.B. Wild, Coord. Chem. Rev. 166 (1997) 291–311;
(b) C. López, S. Pérez, X. Solans, M. Font-Bardía, J. Organomet. Chem. 650
(2002) 258–267. and references therein;
P21/a
Unit-cell dimensions
0
a (AÅ)
14.705(7)
20.909(7)
13.832(6)
90
20.553(7)
13.765(4)
20.546(4)
90
12.578(6)
14.840(5)
21.747(8)
90
0
b (AÅ)
0
c (AÅ)
a
(°)
b (°)
90
90
114.62(2)
90
5284(3)
2
1.420
1.069
90
90
4059(3)
8
1.506
c
(°)
0
(c) J. Albert, J. Granell, G. Muller, J. Organomet. Chem. 691 (2006) 2101–2106;
(d) J.J. Li, G.W. Gribble, Palladium in Heterocyclic Chemistry, Pergamon, NY,
USA, 2000.
U (AÅ3)
4253(3)
8
1.552
1.135
2016
Z
Dcalc (g cmꢀ3
)
[8] (a) A.J. Canty, J. Patel, B.W. Skelton, A.H. White, J. Organomet. Chem. 599
(2000) 195–199;
l
(mmꢀ1
)
1.055
1872
(b) A.J. Canty, J. Patel, B.W. Skelton, A.H. White, J. Organomet. Chem. 607
(2000) 194–202;
(c) M.Q. Slagt, D.A.P. Zwieten, A.J.C.M. Moerkerk, R.J.M.K. Gebbink, G. Van
Koten, Coord. Chem. Rev. 248 (2004) 2275–2282;
F(000)
2288
Crystal size (mm3)
0.2 ꢂ 0.1 ꢂ 0.1 0.2 ꢂ 0.1 ꢂ 0.1
0.2 ꢂ 0.1 ꢂ 0.1
ꢀ17 6 h 6 18,
ꢀ22 6 k 6 22,
ꢀ32 6 l 6 32
2.83–30.00
34736/5649
[0.0552]
95.4%
hkl ranges
ꢀ19 6 h 6 19,
0 6 k 6 29,
0 6 l 6 20
2.24–29.99
13118/6193
[0.0379]
ꢀ30 6 h 6 30,
ꢀ20 6 k 6 20,
ꢀ30 6 l 6 30
2.63–30.00
59442/15023
[0.0983]
(d) C.M. Hartshorn, P.J. Steel, Organometallics 17 (1998) 3487–3496.
[9] (a) C. Bianchini, G. Lenoble, W. Oberhauser, S. Parisel, F. Zanobini, Eur. J. Inorg.
Chem. (2005) 4794–4800;
2h Range (°)
Reflections collected/
unique [R(int)
Completeness to h (%)
(b) A.J. Deeming, I.P. Rothwell, J. Organomet. Chem. 205 (1981) 117–131;
(c) S.W. Lai, T.C. Cheung, M.C.W. Chan, K.K. Cheung, S.M. Peng, C.M. Che, Inorg.
Chem. 39 (2000) 255–262.
]
99.9%
97.4%
(h = 29.99°)
None
0.337 and
0.282
(h = 30.00°)
Empirical
0.89 and 0.87
(h = 30.00°)
Empirical
0.901 and 0.87
[10] (a) A. Pañella, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía, J. Ros, Inorg.
Chim. Acta 359 (2006) 2343–2349;
Absorption correction
Maximum and minimum
transmission
(b) A. Pañella, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía, J. Ros, Inorg.
Chim. Acta 359 (2006) 4477–4483;
(c) M.C. Castellano, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía, J. Ros,
Inorg. Chim. Acta 361 (2008) 2491–2498.
Data/restrains/parameters
6193/0/244
15023/6/562
1.120
5649/2/237
1.549
Goodness-of-fit on F2 (GOF) 0.930
[11] (a) G. Esquius, J. Pons, R. Yáñez, J. Ros, J. Organomet. Chem. 619 (2001) 14–23;
(b) G. Esquius, J. Pons, R. Yanez, J. Ros, R. Mathieu, N. Lugan, B. Donnadieu, Eur.
J. Inorg. Chem. (2002) 2999–3006.
[12] V. Montoya, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 359
(2006) 25–34.
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0578,
wR2 = 0.1101
R1 = 0.2220,
wR2 = 0.1518
R1 = 0.0667,
wR2 = 0.1749
R1 = 0.1116,
wR2 = 0.1963
R1 = 0.0659,
wR2 = 0.0976
R1 = 0.0659,
wR2 = 0.0976
Largest diff0erence peak and 0.978 and
0.924 and ꢀ0.699 0.517 and
[13] V. Montoya, J. Pons, J. García-Antón, X. Solans, M. Font-Bardía, J. Ros,
Organometallics 26 (2007) 3183–3190.
hole (e ÅAꢀ3
)
ꢀ0.804
ꢀ0.354

3404
G. Aragay et al. / Journal of Organometallic Chemistry 693 (2008) 3396–3404
[14] V. Montoya, J. Pons, V. Branchadell, J. García-Antón, X. Solans, M. Font-Bardía, J.
Ros, Organometallics 27 (2008) 1084–1091.
(b) S. Dey, V.K. Jain, A. Knoedler, W. Kaim, X-Ray Struct. Anal. Online 20 (2004)
x127–x128;
[15] V. Montoya, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 358
(2005) 2312–2318.
(c) K.I. Gasanov, A.S. Antsyshkina, G.G. Sadikov, N.A. Ivanova, D.I. Mirzai, I.A.
Efimenko, V.S. Sergienko, Crystallogr. Rep. 47 (2002) 603–609;
(d) L. Pech, Y. Boukousky, A. Kemme, E. Silina, J. Ashaks, A. Sturis, Latuijos
Kimijas Zurnals 4 (2000) 19–25;
(e) G. Zhao, H. Lin, P. Yu, H. Sun, S. Zhu, X. Su, Y. Chen, J. Inorg. Biochem. 73
(1999) 145–149;
[16] F. Bondavalli, O. Bruno, A. Ranise, P. Schenone, S. Russo, A. Loffreda, V. de
Novellis, C. Lo Sasso, E. Marmo, Farm. Ed. Sci. 43 (1988) 725–743.
[17] W.G. Haanstra, W.L. Driessen, R.A.G. de Graff, G.C. Sebregts, J. Suriano, J.
Reedijk, U. Turpeinen, R. Hämäläinen, J.S. Wood, Inorg. Chim. Acta 189 (1991)
243–251.
[18] (a) 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;
(f) E.C. Alyea, S.A. Dias, G. Ferguson, A.J. McAlees, R. McCrindle, P.J. Roberts, J.
Am. Chem. Soc. (1977) 4985–4989.
[29] (a) J. García-Anton, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Eur. J. Inorg. Chem.
(2002) 3319–3327;
(b) D.H. Williams, I. Fleming, Spectroscopic Methods in Organic Chemistry,
McGraw-Hill, London, UK, 1995.
(b) A. Boixassa, J. Pons, A. Virgili, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim.
Acta 340 (2002) 49–55;
[19] S. Komiya, Synthesis of Organometallic Compounds: A Practice Guide, Board,
NY, USA, 1997.
(c) A. Boixassa, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 346
(2003) 151–157;
[20] (a) G.W. Parshall, Acc. Chem. Res. 3 (1970) 139–144;
(b) A. Crispini, M. Ghedini, J. Chem. Soc., Dalton Trans. (1996) 75–80;
(c) J. Albert, J. Granell, R. Tavera, J. Organomet. Chem. 667 (2003) 192–196.
[21] (a) W.J. Geary, Coord. Chem. Rev. 7 (1971) 81–122;
(b) L.K. Thompson, F.L. Lee, E.J. Gabe, Inorg. Chem. 27 (1988) 39–46.
[22] K. Nakamoto, Infrared and Raman spectra of Inorganic and Coordination
Compounds, Wiley & Sons, NY, USA, 1997.
[23] (a) M. Lousame, A. Fernández, M. López-Torres, D. Vázquez-García, J.M. Vila, A.
Suárez, J.M. Ortigueira, J.J. Fernández, Eur. J. Inorg. Chem. (2000) 2055–2062;
(b) S.A. Kurzeev, G.M. Kazankov, A.D. Ryabov, Inorg. Chim. Acta 340 (2002)
192–196.
[24] H. Friebolin, Basic One- and Two-Dimensional NMR Spectroscopy, Willey-VCH
Verlag GmbH, Weinheim, Germany, 1998.
[25] (a) A. Boixassa, J. Pons, J. Ros, R. Mathieu, N. Lugan, J. Organomet. Chem. (2003)
233–239;
(b) J. García-Antón, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Eur. J. Inorg. Chem.
(2003) 2992–3000.
[26] A. Fernandez, E. Pereira, J.J. Fernandez, M. Lopez-Torres, A. Suarez, R. Mosteiro,
J.M. Vila, Polyhedron 21 (2002) 39–48.
(d) J. García-Anton, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Eur. J. Inorg. Chem.
(2003) 3657–3952;
(e) J. García-Anton, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta
355 (2003) 87–94;
(f) A. Boixassa, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 357
(2004) 733–738;
(g) J.A. Pérez, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Inorg. Chim. Acta 358
(2005) 617–622;
(h) J. García-Anton, J. Pons, X. Solans, M. Font-Bardía, J. Ros, Acta Crystallogr. E
60 (2004) m1087–m1089.
[30] H.M. Lee, P.L. Chiu, C. Hu, C. Lai, Y. Chou, J. Organomet. Chem. 690 (2005) 403–
414.
[31] W.L. Driessen, R. M de Vos, A. Etz, J. Reedijk, Inorg. Chim. Acta 235 (1995) 127–
133.
[32] (a) J. Elguero, A. Guerrero, F. Gómez de la Torre, A. de la Hoz, F.A. Jalón, B.R.
Manzano, A. Rodríguez, New J. Chem. 25 (2001) 1050–1060;
(b) K. Li, J. Darkwa, I.A. Guzei, S.F. Mapolie, J. Organomet. Chem. 660 (2002)
108–115.
[33] G.M. Sheldrick, SHELXS-97: Program for Crystal Structure Determination,
University of Göttingen, Göttingen, Germany, 1997.
[34] G.M. Sheldrick, SHELXL-97: Program for Crystal Structure Refinement, University
of Göttingen, Göttingen, Germany, 1997.
[27] F.A. Allen, Acta Crystallogr. B 58 (2002) 380–388.
[28] (a) R.P. Hughes, M.A. Meyer, M.D. Tawa, A.J. Ward, A. Williamson, A.L.
Rheingold, L.N. Zakharov, Inorg. Chem. 43 (2004) 747–756;