Reactivity of the pyrazolatopalladium(II) complexes [Pd(dmpz) 2(Hdmpz)2] and [Pd2(μ-dmpz) 2(dmpz)2(Hdmpz)2] towards carboxylic acids: Hydrogen bonds as the driving force that determines the nature of the final products

Article abstract of DOI:10.1002/ejic.200500791

The compound [Pd(Hdmpz)₄](O₂CCH ₂NHCOCH₃)₂ (1; (Hdmpz = 3,5-dimethylpyrazole) has been obtained by treatment of [Pd(dmpz)₂(Hdmpz)₂] (A) with two equivalents of N-acetylglycine (HO₂CCH ₂NHCOCH₃). The X-ray study on a crystal of 1 revealed that the N-acetylglycinate anion links to the cationic complex [Pd(Hdmpz) ₄]²⁺ through the carboxylate group by charge assisted N-H⁽⁺⁾...O^(-) hydrogen bonds. Additionally, the remaining N-H and C=O groups allow the N-acetylglycinate anions to self-assemble through N-H...O hydrogen bonds to generate infinite chains. The compounds [Pd₂(μ-dmpz)₂(O₂CCH₂NHCOCH ₃-κO)₂(Hdmpz)₂] (2) and [Pd ₂(μ-dmpz)₂(O₂CC₆H ₄-R-κO)₂(Hdmpz)₂] [R = m-NO₂ (3a), p-N(CH₃)₂ (3b), p-NH₂ (3c), p-OCH ₃ (3d), p-OH (3e)] have been obtained by treatment of [Pd ₂(μ-dmpz)₂(dmpz)₂-(Hdmpz)₂] (B) with two equivalents of the monocarboxylic acids N-acetylglycine (HO ₂CCH₂NHCOCH₃) and the benzoic derivatives HO₂CC₆H₄R [R = m-NO₂, p-N(CH ₃)₂, P-NH₂, p-OCH₃, p-OH] respectively. The X-ray study on complexes 3d and 3e shows that in these complexes the carboxylate anion bonded to one Pd atom and the terminal Hdmpz group bonded to the other one have the right arrangement to establish an N-H...O hydrogen bond. The H...O and N...O distances are in the range of those corresponding to charge-assisted N-H⁽⁺⁾...O ^(-) interactions. In complexes 3a-3e, the H atoms of the terminal Hdmpz groups can be replaced by Ag⁺ to give the mixed-metal complexes [Pd₂Ag₂(μ-dmpz)₄(μ-O₂CC ₆H₄-R-κO)₂(Hdmpz)₂] [R = m-NO₂ (4a), p-N(CH₃)₂ (4b), p-NH₂ (4c), p-OCH₃ (4d), p-OH (4e)]. Compounds 4a-4e, which exhibit a transoid conformation of the carboxylate groups with respect to the Pd...Pd line, isomerise to the cisoid species (4a′-4e′). The X-ray structure of the DMSO adduct of 4d′ is also reported. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200500791

FULL PAPER
DOI: 10.1002/ejic.200500791
Reactivity of the Pyrazolatopalladium(II) Complexes [Pd(dmpz)2(Hdmpz)2] and
[Pd2(µ-dmpz)2(dmpz)2(Hdmpz)2] towards Carboxylic Acids: Hydrogen Bonds as
the Driving Force That Determines the Nature of the Final Products
Irene Ara,[a] Juan Forniés,*[a] Roberto Lasheras,[b] Antonio Martín,[a] and Violeta Sicilia*[b]
Keywords: Carboxylate ligands / Heterometallic complexes / Hydrogen bonds / N ligands / Palladium
The compound [Pd(Hdmpz)4](O2CCH2NHCOCH3)2 (1;
(Hdmpz = 3,5-dimethylpyrazole) has been obtained by treat-
ment of [Pd(dmpz)2(Hdmpz)2] (A) with two equivalents of N-
acetylglycine (HO2CCH2NHCOCH3). The X-ray study on a
crystal of 1 revealed that the N-acetylglycinate anion links to
the cationic complex [Pd(Hdmpz)4]2+ through the carboxylate
group by charge assisted N–H(+)···O(–) hydrogen bonds. Ad-
ditionally, the remaining N–H and C=O groups allow the N-
acetylglycinate anions to self-assemble through N–H···O hy-
drogen bonds to generate infinite chains. The compounds
[Pd2(µ-dmpz)2(O2CCH2NHCOCH3-κO)2(Hdmpz)2] (2) and
[Pd2(µ-dmpz)2(O2CC6H4-R-κO)2(Hdmpz)2] [R = m-NO2 (3a),
p-N(CH3)2 (3b), p-NH2 (3c), p-OCH3 (3d), p-OH (3e)] have
been obtained by treatment of [Pd2(µ-dmpz)2(dmpz)2-
(Hdmpz)2] (B) with two equivalents of the monocarboxylic
acids N-acetylglycine (HO2CCH2NHCOCH3) and the ben-
zoic derivatives HO2CC6H4R [R = m-NO2, p-N(CH3)2, p-NH2,
p-OCH3, p-OH] respectively. The X-ray study on complexes
3d and 3e shows that in these complexes the carboxylate
anion bonded to one Pd atom and the terminal Hdmpz group
bonded to the other one have the right arrangement to estab-
lish an N–H···O hydrogen bond. The H···O and N···O dis-
tances are in the range of those corresponding to charge-
assisted N–H(+)···O(–) interactions. In complexes 3a–3e, the H
atoms of the terminal Hdmpz groups can be replaced by Ag+
to give the mixed-metal complexes [Pd2Ag2(µ-dmpz)4(µ-
O2CC6H4-R-κO)2(Hdmpz)2] [R = m-NO2 (4a), p-N(CH3)2 (4b),
p-NH2 (4c), p-OCH3 (4d), p-OH (4e)]. Compounds 4a–4e,
which exhibit a transoid conformation of the carboxylate
groups with respect to the Pd···Pd line, isomerise to the cisoid
species (4aЈ–4eЈ). The X-ray structure of the DMSO adduct
of 4dЈ is also reported.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
azoles (HRpz) and/or pyrazolates (Rpz) as ligands have been
reported up to now, one of them, [Pd2(µ-dmpz)2(dmpz)2-
(Hdmpz)2] having been published recently by us.[14] This
kind of compound often contains inter-[11–13] or intramol-
ecular[12,14] N–H···N hydrogen bonds involving neutral pyr-
azole (HRpz) and anionic pyrazolate (Rpz) groups, and the
protons of the coordinated pyrazoles can be replaced by
metal ions as CuI, AgI and AuI to give heterometallic poly-
nuclear complexes.[12–14]
The mono- and dinuclear complexes [Pd(dmpz)2-
(Hdmpz)2] (A)[13] and [Pd2(µ-dmpz)2(dmpz)2(Hdmpz)2]
(B)[14] have terminal dmpz and Hdmpz ligands bonded to
each palladium centre, that is, on each side of both com-
plexes there is a dmpz group, which is a hydrogen-bond
acceptor, and an Hdmpz ligand, which is a hydrogen-bond
donor. We therefore considered it of interest to use these
compounds as starting materials to obtain organic–organo-
metallic hydrogen-bonded networks by reaction of both
complexes with carboxylic acids. A carboxylic acid group
(COOH) can form complementary hydrogen bonds with the
dmpz and Hdmpz ligands on the same side of each complex
(Figure 1a) or transfer its proton to the dmpz ligand.
Should this be the case, charge-assisted N–H(+)···O(–) hydro-
gen bonds would be formed between complex cations and
Introduction
The coordination chemistry of neutral pyrazole (HRpz)
or anionic pyrazolate (Rpz) ligands has been intensively de-
veloped over many years[1] and has been thoroughly re-
viewed.[2–5] Recently, unprecedented compounds showing
new bonding modes for pyrazolate ligands have been re-
ported.[6–10] In spite of this, the number of palladium and
platinum compounds is rather low. Only a few examples of
mono- ([Pt(pz)2(Hpz)2],[11,12] [Pt(Hpz)4]Cl2,[11] [Pd(Hpz)4]-
Cl2,[12] [Pd(dmpz)2(Hdmpz)2][13]), di- {[Pd2(µ-dmpz)2(dmpz)2-
(Hdmpz)2],[14] [Pd2(µ-3-tBupz)2(3-tBupz)2(H3-tBupz)2],[12]
[15]
[Pd2(µ-pz)2(Hpz)4](BF4)2
}
or
trinuclear
([{Pt(µ-
pz)2}3],[12,16]
[{Pd(µ-pz)2}3],[12]
[{Pd(µ-4-Mepz)2}3],[12]
[{Pd(µ-3-Phpz)2}3][17]) compounds containing only pyr-
[a] Departamento de Química Inorgánica, Instituto de Ciencia de
Materiales de Aragón, Facultad de Ciencias, Universidad de
Zaragoza-CSIC,
Pl. S. Francisco s/n 50009 Zaragoza, Spain
E-mail: juan.fornies@unizar.es
[b] Departamento de Química Inorgánica, Instituto de Ciencia de
Materiales de Aragón, Escuela Universitaria de Ingeniería
Técnica Industrial, Universidad de Zaragoza-CSIC,
Campus Universitario del Actur, Edificio Torres Quevedo,
50018, Zaragoza, Spain
E-mail: sicilia@unizar.es
948
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Reactivity of Pyrazolatopalladium() Complexes towards Carboxylic Acids
FULL PAPER
carboxylate anions yielding a heteromeric synthon of type of coordinated Hdmpz in the dinuclear complexes by AgI
R2(10)[18,19] (Figure 1b). Additionally, the substitution of gives new heteropolynuclear Pd-Ag ones.
dmpz by carboxylate groups could also take place.
Results and Discussion
Reactivity of [Pd(dmpz)2(Hdmpz)2] (A) towards the
Monoprotic Weak Acids N-Acetylglycine and HO2CC6H4-
R [R = m-NO2, p-N(CH3)2, p-NH2, p-OCH3, p-OH]
[Pd(dmpz)2(Hdmpz)2] (A) reacts with two equivalents of
N-acetylglycine in dichloromethane/methanol solution to
give [Pd(Hdmpz)4](O2CCH2NHCOCH3)2 (1) as a pure
compound in a very high yield (path a in Scheme 1) by se-
lective protonation of the anionic monodentate dmpz li-
Figure 1. a) Complementary hydrogen bonds between the neutral
gands. The X-ray study of a crystal of 1 revealed that the
carboxylic group and the “cis-Pd(dmpz)(Hdmpz)” fragment. b)
N-acetylglycinate anion interacts with the cationic complex
Charge-assisted N–H(+)···O(–) hydrogen bonds between a carboxyl-
[Pd(Hdmpz)4]2+ through N–H···O hydrogen bonds.
ate anion and the cationic “cis-Pd(Hdmpz)2” fragment.
The reactions of [Pd(dmpz)2(Hdmpz)2] (A) with the ben-
In this paper we report the reactivity of complexes zoic derivatives HO2CC6H4-R [R = m-NO2, p-N(CH3)2, p-
[Pd(dmpz)2(Hdmpz)2] (A) and [Pd2(µ-dmpz)2(dmpz)2- NH2, p-OCH3, p-OH] under similar conditions do not give
1
(Hdmpz)2] (B) towards monocarboxylic acids such as N- rise to pure compounds: their H NMR spectra seem to
acetylglycine (HO2CCH2NHCOCH3) and benzoic acid de- indicate that species of stoichiometry [Pd(Hdmpz)4]-
rivatives [HO2CC6H4-R, R = m-NO2, p-N(CH3)2, p-NH2, (O2CC6H4-R)2 [R = m-NO2, p-N(CH3)2, p-NH2, p-OCH3,
p-OCH3, p-OH]. Some of these carboxylic acids contain an p-OH] could be present in all mixtures, but we have not
additional functional group that is able to form an extra been able to separate and characterise them.
1
molecular hydrogen bond. As a result, a new mononuclear
Elemental analyses and the IR and H NMR spectro-
complex and new dinuclear heteroleptic compounds con- scopic data of [Pd(Hdmpz)4](O2CCH2NHCOCH3)2 (1) (see
taining pyrazolate and carboxylate ligands in the same Experimental Section) are in agreement with this stoichi-
molecule have been obtained. Replacement of the protons ometry, which was confirmed later by an X-ray diffraction
Scheme 1.
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I. Ara, J. Forniés, R. Lasheras, A. Martín, V. Sicilia
FULL PAPER
1
study. The H NMR spectrum of 1 in solution reveals the
equivalence of the four Hdmpz ligands since only one set
of signals is observed [δ = 15.45 (s, 4 H, N–H), 5.72 (s, 4
H, H4), 2.49 (s, 12 H, CH3), 2.25 (s, 12 H, CH3) ppm]. The
two N-acetylglycinate anions also give only one set of sig-
3
nals [δ = 6.56 (s, 2 H, N–H), 4.05 (d, JH,H = 3.74 Hz, 4 H,
CH2), 2.06 (s, 6 H, CH3) ppm].
The molecular and supramolecular structures of com-
pound 1 are shown in Figures 2 and 3, respectively. Table 1
lists a selection of intra- and intermolecular bond distances
and angles.
Figure 2. Molecular structure of 1 (50% probability ellipsoids).
In the [Pd(Hdmpz)4]2+ part of the complex the Pd centre
shows an almost square-planar coordination environment
with all the Pd–N bond lengths in the range of those found
in palladium complexes with this kind of li-
gand.[6,11–13,15–17,20,21] Each pair of mutually trans Hdmpz
groups are coplanar to each other (interplanar angle of 0°
between planes 2 and 2Ј and planes 3 and 3Ј. See Table 1
for the definition of the planes used in this discussion) and
almost perpendicular to the other pair of Hdmpz groups
[interplanar angle of 86.6(1)°]. All Hdmpz ligands are al-
most perpendicular to the best least-squares coordination
plane of the metal centre (plane 1), since the interplanar
angles are 80.9(1)° [planes 1 and 2 (2Ј)] and 76.7(1)° [planes
1 and 3 (3Ј)].[22] The Hdmpz groups are turned in such a
way that the N–H bonds of the two Hdmpz ligands in the
cis positions point roughly to the same side of the palla-
dium coordination plane.
The N-acetylglycinate anions are bonded to the cation
through hydrogen bonds. The two N–H groups pointing to
the same side of the palladium coordination plane form N–
H···O hydrogen bonds with the two oxygen atoms of the
same carboxylate group. These N–H···O hydrogen bonds
seem to be quite strong as the H···O and N···O distances
are perceptibly shorter than those involved in neutral mole-
Figure 3. Supramolecular structure of 1.
Table 1. Bond lengths [Å] and angles [°] for [Pd(Hdmpz)4]-
(O2CCH2NHCOCH3)2 (1).[a]
Pd–N(1)
C(11)–O(1)
N(1)–Pd–N(3)
2.029(2)
1.252(4)
Pd–N(3)
C(11)–O(2)
2.018(2)
1.247(3)
91.16(9) N(1)–Pd–N(3Ј) 88.84(9)
N–(H)···O
d(N–H) d(H···O) d(N···O) Ͻ(NHO)
N(2)–(H2N)···O(1) 0.89(4)
N(4)–(H4N)···O(2) 0.95(4)
N(5)–(H5N)···O(3) 0.79(3)
1.76(4)
1.73(4)
2.16(3)
2.647(3) 166(3)
2.645(3) 164(4)
2.937(3) 168(3)
Plane1: Pd, N(1), N(3), N(1Ј), N(3Ј)
Plane2: N(1), N(2), C(1), C(2), C(3)
Plane2Ј: N(1Ј), N(2Ј), C(1Ј), C(2Ј), C(3Ј)
Plane3: N(3), N(4), C(6), C(7), C(8)
Plane3Ј: N(3Ј), N(4Ј), C(6Ј), C(7Ј), C(8Ј)
[a] The symmetry transformation used to generate the equivalent
primed atoms is –x, –y + 1, –z + 1.
cules[23,24] and are even at the lower end of the range ob- been transferred to the monodentate dmpz groups[31] such
served for charge-assisted N–H(+)···O(–) hydrogen that the complex cations and the carboxylate anions are
bonds.[24–30] According to these structural data, the C–O joined by a heteromeric synthon of type R2(10)[18,19] (Fig-
distances within the COO– moieties indicate that the car- ure 1b). Compound 1 is a new example in which the N–
boxylic acid does not retain its acidic hydrogen, which has H···O interaction is reinforced by an electrostatic one, the
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Reactivity of Pyrazolatopalladium() Complexes towards Carboxylic Acids
FULL PAPER
H-bond acceptor being a carboxylate anion and the H- of the pyrazolate anion Rpz– to the metal centre.[33,34] The
bond donor an organometallic cation containing N–H substitution of Rpz– anions by carboxylate groups has sel-
groups.
dom been used as carboxylate complexes are much easier
In addition, the N-acetylglycinate anions self-assemble to make than pyrazolates. As far as we know, only [Ru2(µ-
through N–H···O links to generate infinite chains. The O2CR)2(Hpz)2(CO)4] has been prepared in such a way;[35]
H···O and N···O distances are longer than those involving the carboxylic acid is added in a large excess to induce pro-
the carboxylate group, but within the range observed for tonation of all Rpz groups in the starting material. How-
this kind of interaction between neutral molecules.[23,25] The ever, in the synthesis of complexes 2 and 3a–3e the carbox-
supramolecular architecture of compound 1 is a 2D net- ylic acids are added to compound B in a stoichiometric
work which can be described as being formed by infinite manner (1:2) and selective protonation of the terminal
chains of N-acetylglycinate anions (CH3CONHCH2COO–) dmpz groups takes place. Thus, the selectivity of this pro-
linked through the carboxylate group (COO–) to the cess is the key to synthesising mixed-ligand complexes.
[Pd(Hdmpz)4]2+ cations by charge-assisted N–H(+)···O(–)
hydrogen bonds.
An X-ray study was performed on complexes 3d and 3e
to try to ascertain if the OH groups of the carboxylate
anions of different complexes are involved in hydrogen-
bonding interactions to generate supramolecular structures.
Unfortunately, no supramolecular aggregates were found
and both complexes show discrete dinuclear structures. The
molecular structures of complexes 3d and 3e are shown in
Figures 4 and 5, respectively, and a selection of bond
lengths and angles is given in Tables 2 and 3.
Reactivity of [Pd2(µ-dmpz)2(dmpz)2(Hdmpz)2] (B) towards
the Monoprotic Weak Acids N-Acetylglycine and
HO2CC6H4-R [R = m-NO2, p-N(CH3)2, p-NH2, p-OCH3,
p-OH]
[Pd2(µ-dmpz)2(dmpz)2(Hdmpz)2] (B) reacts with the mo-
nocarboxylic acids N-acetylglycine and the benzoic deriva-
tives HO2CC6H4-R [R = m-NO2, p-N(CH3)2, p-NH2, p-
OCH3, p-OH] in a 1:2 molar ratio, but in a different way to
[Pd(dmpz)2(Hdmpz)2] (A). In these cases selective proton-
ation of the monodentate dmpz groups (one from each pal-
ladium atom), their elimination as Hdmpz, and their fur-
ther displacement by the carboxylate anions generated takes
place. These carboxylate groups interact with the palladium
atoms in a monodentate way to give compounds [Pd2(µ-
dmpz)2(O2CCH2NHCOCH3-κO)2(Hdmpz)2]
(2)
and
[Pd2(µ-dmpz)2(O2CC6H4-R-κO)2(Hdmpz)2] [R = m-NO2
(3a), p-N(CH3)2 (3b), p-NH2 (3c), p-OCH3 (3d), p-OH (3e)]
(paths b and c in Scheme 1).
The IR absorptions corresponding to the carboxylate
groups (see Experimental Section) are in agreement with
the monodentate coordination mode of these anions,[32] as
confirmed by the X-ray structures of compounds 3d and 3e.
According to the symmetry of these compounds (C2),
Figure 4. Molecular structure of 3d.
1
their H NMR spectra show a set of signals corresponding
to one half of each complex, namely “Pd(µ-
dmpz)(O2CC6H4-R-κO)(Hdmpz)” (see Experimental Sec-
tion, Scheme 2). The methyl signals corresponding to bridg-
ing dmpz or terminal Hdmpz groups were unambiguously
assigned by NOE experiments.
Scheme 2.
A common way to synthesise pyrazolate complexes is by
treating carboxylate derivatives with the neutral pyrazole
(HRpz) in the presence of NEt3. These reactions proceed
Figure 5. Molecular structure of 3e.
Complexes 3d and 3e are dinuclear species of PdII with
with elimination of the carboxylic acid and coordination two 3,5-dmpz groups bridging the two metal atoms, which
Eur. J. Inorg. Chem. 2006, 948–957
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951

I. Ara, J. Forniés, R. Lasheras, A. Martín, V. Sicilia
FULL PAPER
Table 2. Bond lengths [Å] and angles [°] for [Pd2(µ-dmpz)2(O2C- do not retain their acidic hydrogen, which has been trans-
C6H4OCH3-κO)2(Hdmpz)2] (3d).
ferred to the monodentate dmpz groups to generate Hdmpz
ones.[31]
Pd(1)–O(1)
2.001(2)
1.989(2)
2.015(2)
2.001(2)
1.271(3)
1.278(3)
92.74(8)
89.04(9)
89.90(8)
89.97(9)
122.89
Pd(1)–N(1)
Pd(1)–N(7)
Pd(2)–N(3)
Pd(2)–N(8)
C(21)–O(2)
C(29)–O(5)
O(1)–Pd(1)–N(1)
N(7)–Pd(1)–N(1)
O(4)–Pd(2)–N(3)
N(6)–Pd(2)–N(3)
C(29)–O(4)–Pd(2)
2.016(2)
1.994(2)
2.011(2)
1.989(2)
1.234(3)
1.232(3)
86.06(9)
92.64(9)
90.26(8)
90.00(9)
116.60
Pd(1)–N(5)
The monodentate carboxylate anion bonded to a Pd
atom and the terminal Hdmpz group bonded to the other
Pd atom have an adequate arrangement to establish an N–
H···O hydrogen bond. The H···O and N···O distances are in
the range of those corresponding to charge-assisted N–H(+)
···O(–) bonds. In addition, the N–H···O angles are in the
range observed for these kinds of interactions.[24–30]
Pd(2)–O(4)
Pd(2)–N(6)
C(21)–O(1)
C(29)–O(4)
N(5)–Pd(1)–O(1)
N(5)–Pd(1)–N(7)
N(8)–Pd(2)–O(4)
N(8)–Pd(2)–N(6)
C(21)–O(1)–Pd(1)
N–(H)···O
d(N–H)
d(H···O) d(N···O)
Ͻ(NHO)
Reactivity of [Pd2(µ-dmpz)2(O2CC6H4-R-κO)2(Hdmpz)2] [R
= m-NO2 (3a), p-N(CH3)2 (3b), p-NH2(3c), p-OCH3 (3d),
p-OH (3e)] towards AgClO4
N(2)-(H2)···O(5)
N(4)-(H4)···O(2)
0.88
0.88
1.85
1.85
2.725(3)
2.703(3)
173.8(2)
163.3(2)
The reactions of [Pd2(µ-dmpz)2(O2CC6H4-R-κO)2-
(Hdmpz)2] [R = m-NO2 (3a), p-N(CH3)2 (3b), p-NH2 (3c),
p-OCH3 (3d), p-OH (3e)] with AgClO4 in a 1:2 molar ratio
in the presence of NEt3 produce the deprotonation of the
terminal Hdmpz groups and formation of [Pd2Ag2(µ-dmpz)4-
(O2CC6H4-R-κO)2] [R = m-NO2 (4a), p-N(CH3)2 (4b), p-
NH2(4c), p-OCH3 (4d), p-OH (4e)]. In these reactions the
NHEt3ClO4 by-product is eliminated by washing with
methanol, where compounds 4a–4e are insoluble.
Table 3. Bond lengths [Å] and angles [°] for [Pd2(µ-dmpz)2(O2C-
C6H4OH-κO)2(Hdmpz)2] (3e).
Pd(1)–N(1)
Pd(1)–O(1)
Pd(2)–N(4)
Pd(2)–N(6)
C(1)–O(1)
C(28)–O(4)
N(3)–Pd(1)–O(1)
N(3)–Pd(1)–N(5)
N(6)–Pd(2)–O(4)
N(4)–Pd(2)–N(6)
2.017(2)
2.004(2)
1.986(2)
1.995(2)
1.289(3)
1.292(3)
91.72(8)
89.76(8)
89.92(8)
89.75(8)
Pd(1)–N(5)
Pd(1)–N(3)
Pd(2)–O(4)
Pd(2)–N(7)
C(1)–O(2)
C(28)–O(5)
O(1)–Pd(1)–N(1)
N(5)–Pd(1)–N(1)
O(4)–Pd(2)–N(7)
N(4)–Pd(2)–N(7)
1.998(2)
1.988(2)
2.0098(17)
2.014(2)
1.239(3)
1.234(3)
88.06(8)
90.48(8)
90.03(8)
90.39(8)
This method has previously been used in the synthesis
of the Pd-Ag pyrazolate complexes [Pd2Ag4(dmpz)8][13] and
[Pd2Ag2(dmpz)6][14] from [Pd(dmpz)2(Hdmpz)2] and [Pd(µ-
dmpz)2(dmpz)2(Hdmpz)2], respectively.
C(1)–O(1)–Pd(1) 124.29(16)
C(28)–O(4)–Pd(2) 118.23(16)
N-(H)···O
d(N–H)
d(H···O)
d(N···O)
Ͻ(NHO)
1
Elemental analysis and IR and H NMR spectroscopic
N(2)–(H2)···O(5)
N(8)–(H8)···O(2)
0.88
0.88
1.827(2)
1.852(2)
2.704(3)
2.729(3)
174.26(18)
174.47(18)
data (Experimental Section, Scheme 2) are in agreement
with the stoichiometry proposed and presented in
Scheme 1. With the exception of the signal corresponding
to the acidic N–H protons, the number of signals observed
are located at 3.269 (3d) and 3.272 Å (3e). The Pd2N4 ring
shows a typical boat-like conformation, the dihedral angle
between both Pd–N–N–Pd fragments being 73.5(1)° (3d)
and 72.9(1)° (3e).[22] In addition, each Pd atom is bonded
to a nitrogen of a neutral, monodentate 3,5-dimethylpyra-
zole and to an oxygen of the carboxylate anion to complete
a square-planar coordination environment. The angles de-
fined by two ligands in cis positions and the metal centre
are close to 90°. The Pd–N distances are in the range of
distances found in other complexes with this kind of li-
gand.[6,11–17,20,21,36] No significant differences are observed
in the Pd–N distances corresponding to terminal Hdmpz or
bridging dmpz groups. The Pd–O bond lengths (ca. 2.00 Å)
are similar to those observed in palladium complexes with
monodentate carboxylate groups.[37–43] The two Pd–O–C
angles are surprisingly different to each other: while one of
them is smaller than 120° [C(29)–O(4)–Pd(2): 116.6° (3d);
C(28)–O(4)–Pd(2): 118.2° (3e)] and similar to those found
in other complexes with this type of ligand, such as
[Pd(phen)(MeCO2)2] (Pd–O–C: 114.3° and 118.5°),[37]
[Pd{3,3Ј-[CH2CH(COOEt)2]-2,2Ј-byp-κN,NЈCβ}(O2CCH3)]
(Pd–O–C: 116.9°–119.9°),[38] the other is, unusually, greater
than 120° [C(21)–O(1)–Pd(1): 122.9° (3d); C(1)–O(1)–Pd(1):
124.3° (3e)]. The C–O distances within the COO– moieties
1
in the H NMR spectra of compounds 4a–e is the same as
that observed in the spectra of the starting complexes (3a–
3e). We thus propose the molecular structure represented in
Scheme 3a for compounds 4a–e, in which the two acidic H
atoms of complexes 3a–3e have been replaced by Ag ones,
keeping the carboxylate groups in a transoid conformation
with respect to the Pd···Pd axis. If acetone solutions of com-
pounds 4a–4e are left at room temperature until the solvent
has completely evaporated the resulting solids exhibit dif-
1
ferent H NMR spectra (Experimental Section, Scheme 2)
to those shown by the starting compounds (4a–4e), reveal-
ing a change in the molecular structure to give the isomers
1
4aЈ–4eЈ (Scheme 3b). The H NMR spectra of these com-
plexes display two signals corresponding to the H4 atoms
(1.232–1.292 Å) indicate that the carboxylic acid molecules Scheme 3.
952
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Eur. J. Inorg. Chem. 2006, 948–957

Reactivity of Pyrazolatopalladium() Complexes towards Carboxylic Acids
FULL PAPER
of the Pd2(µ-dmpz)2 groups. A cisoid arrangement of the dium atoms bridged by two 3,5-dmpz groups in such a way
carboxylate groups with respect to the Pd···Pd axis could that the Pd2N4 ring shows a typical boat-like conformation,
account for these two signals.
the dihedral angle between both Pd–N–N–Pd fragments be-
Single crystals of [Pd2Ag2(µ-dmpz)4(p-O2CC6H4OCH3- ing 70.5(2)°.[22] Both palladium atoms complete their
κO)2(DMSO)] were obtained from a solution of 4d in square-planar coordination environments by bonding to
1
DMSO. Its H NMR spectrum is similar to that of 4dЈ in one nitrogen of another 3,5-dmpz group and one oxygen of
DMSO, indicating that the structure of the skeleton of both the carboxylate anion. In this complex the two 3,5-dmpz
complexes is the same. The X-ray study of a single crystal groups outside the Pd2N4 ring are in cisoid positions with
allowed us to unambiguously establish the structure pro- respect to the Pd···Pd axis, as are both carboxylate groups,
posed for these compounds. The molecular structure of although in the starting complex [Pd2(µ-dmpz)2(O2CC6H4-
[Pd2Ag2(µ-dmpz)4(p-O2CC6H4OCH3-κO)2(DMSO)]
is OCH3-κO)2(Hdmpz)2] (3d) transoid positions are observed.
shown in Figure 6, and Table 4 contains a selection of bond The Pd–N[6,11–17,20,21,36] and Pd–O[44,45]distances are in the
lengths and angles in the complex.
range of those found in palladium compounds with the
same kind of ligands.
One of the silver atoms, Ag(2), is bonded to two 3,5-
dmpz groups in an almost linear coordination environment
[N(8)–Ag(2)–N(6) = 176.9(3)°]. The 3,5-dmpz groups bridg-
ing Ag(2) and both palladium atoms are almost coplanar
[interplanar angle of 4.7(3)°] and the dihedral angles be-
tween them and the coordination planes of the correspond-
ing palladium atoms are 52.3(3)° [Pd(1)] and 51.5(3)°
[Pd(2)].[22] The Ag–N distances are similar to those found
in other silver pyrazolate complexes.[13]
The other silver atom, Ag(1), is coordinated to two oxy-
gen atoms, one from each carboxylate group, which act as a
bridge between this atom] and both palladium atoms. Ag(1)
completes its coordination environment with the oxygen of
one molecule of DMSO used as crystallisation solvent. All
Ag–O distances are in the range of those observed in silver
complexes with these kinds of ligands.[44–49] Ag(1) also con-
tacts with Ag(2), the Ag(1)···Ag(2) distance being
2.9208(12) Å, which is similar to distances found in other
complexes with Ag···Ag interactions.[50–53] In addition,
Ag(1) contacts with Pd(1) [Ag(1)···Pd(1) = 3.0652(12) Å]
and Pd(2) [Ag(1)···Pd(2) = 2.9586(12) Å] and the Ag–Pd
vectors are nearly perpendicular to the square coordination
planes of the Pd(1) and Pd(2) centres [9.2(1)° and 9.7(1)°
respectively]. Both facts indicate weak Pd···Ag interac-
tions.[54,55]
The planar “C–CO2” fragment from the carboxylate
group bonded to Pd(1) forms angles of 69.8(3)° and
72.3(4)° with the palladium coordination plane and the 3,5-
dmpz group outside the Pd2N4 ring, respectively.[22] The
same parameters for Pd(2) are 86.6(3)° and 87.1(4)°. The
interplanar angle between both “C–CO2” fragments is
68.1(4)°.
Figure 6. Molecular structure of [Pd2Ag2(µ-dmpz)4(µ-O2CC6H4-
OCH3)2(DMSO)].
Table 4. Bond lengths [Å] and angles [°] for [Pd2Ag2(µ-
dmpz)4(O2CC6H4OCH3-κO)2(DMSO)] from 4dЈ.
Pd(1)–N(1)
Pd(1)–N(5)
Pd(2)–N(2)
Pd(2)–N(7)
Ag(1)–O(2)
Ag(1)–O(7)
Ag(2)–N(8)
Ag(1)···Pd(2)
O(4)–Pd(1)–N(5)
N(3)–Pd(1)–N(1)
O(1)–Pd(2)–N(7)
N(7)–Pd(2)–N(4)
O(2)–Ag(1)–O(7)
O(5)–Ag(1)–O(7)
O(5)–Ag(1)–Ag(2)
O(2)–Ag(1)–Pd(2)
O(7)–Ag(1)–Pd(2)
2.025(7) Pd(1)–N(3)
2.020(6) Pd(1)–O(4)
1.991(7) Pd(2)–N(4)
2.019(7) Pd(2)–O(1)
2.259(6) Ag(1)–O(5)
2.409(8) Ag(2)–N(6)
2.075(6) Ag(1)···Ag(2)
2.9586(12) Ag(1)···Pd(1)
2.002(6)
2.007(6)
1.994(6)
2.008(6)
2.262(6)
2.069(7)
2.9208(12)
3.0652(12)
90.8(3)
90.5(3)
88.8(3)
89.2(3)
91.3(3)
98.4(3)
98.8(2)
N(5)–Pd(1)–N(3)
N(1)–Pd(1)–O(4)
O(1)–Pd(2)–N(2)
N(4)–Pd(2)–N(2)
O(2)–Ag(1)–O(5)
O(2)–Ag(1)–Ag(2)
89.9(2)
90.2(3)
89.4(3)
117.2(3)
136.4(2)
73.8(2)
136.96(16)
72.27(3)
70.22(17)
69.57(3)
176.9(3)
85.45(18)
Conclusion
106.4(2) O(7)–Ag(1)–Ag(2)
76.0(2) O(5)–Ag(1)–Pd(2)
120.6(2) Ag(2)–Ag(1)–Pd(2)
In summary, N-acetylglycine reacts with [Pd(dmpz)2-
(Hdmpz)2] (A) in a 2:1 molar ratio to give [Pd(Hdmpz)4]-
(O2CCH2NHCOCH3)2 (1) by selective protonation of the
anionic monodentate dmpz ligands. The cationic complex
[Pd(Hdmpz)4]2+ is bonded to the N-acetylglycinate anion
through charge-assisted N–H(+)···O(–) hydrogen bonds. N-
O(2)–Ag(1)–Pd(1) 124.67(19) O(5)–Ag(1)–Pd(1)
O(7)–Ag(1)–Pd(1)
Pd(2)–Ag(1)–Pd(1)
136.2(2) Ag(2)–Ag(1)–Pd(1)
69.33(3) N(6)–Ag(2)–N(8)
N(6)–Ag(2)–Ag(1) 94.03(19) N(8)–Ag(2)–Ag(1)
[Pd2Ag2(µ-dmpz)4(p-O2CC6H4OCH3-κO)2(DMSO)] is a acetylglycine also reacts with [Pd2(µ-dmpz)2(dmpz)2-
palladium/silver tetranuclear compound with both palla- (Hdmpz)2] (B) in a 2:1 molar ratio, but in this case, the
Eur. J. Inorg. Chem. 2006, 948–957
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953

I. Ara, J. Forniés, R. Lasheras, A. Martín, V. Sicilia
FULL PAPER
added to a yellow solution of B (0.2496 g, 0.318 mmol) in CH2Cl2
(35 mL). The mixture was stirred at room temperature for 2 h and
the solvent was then evaporated to dryness. Addition of diethyl
ether (12 mL) to the residue gave 3a as a yellow solid, which was
filtered off and dried (0.055 g, 32% yield). C34H38N10O8Pd2
(927.54): calcd. C 44.03, H 4.13, N 15.09; found C 43.93, H 4.27,
selective protonation of the monodentate dmpz groups (one
from each palladium atom) is followed by their displace-
ment by the carboxylate anions generated and their elimi-
nation as Hdmpz. In the resulting compound, [Pd2(µ-dmpz)2-
(O2CCH2NHCOCH3-κO)2(Hdmpz)2] (2), the monodentate
carboxylate groups exhibit a transoid conformation with re-
spect to the Pd···Pd axis. The benzoic derivatives,
HO2CC6H4-R [R = m-NO2, p-N(CH3)2, p-NH2, p-OCH3,
p-OH] react with B in the same way that N-acetylglycine
N 14.83. IR: ν
= 1631 cm–1 (vs), 1586 (s), 1531 (s), 1378 (vs),
˜
max
1
1348 (s), 1155 (m), 1072 (m), 820 (m), 782 (m), 760 (m). H NMR
(300 MHz, [D6]acetone, 23 °C): δ = 1.94 (s, 6 H, CH3, dmpz), 2.36
(s, 6 H, CH3, Hdmpz), 2.40 (s, 6 H, CH3, dmpz), 2.93 (s, 6 H, CH3,
does to give compounds [Pd2(µ-dmpz)2(O2CC6H4-R-κO)2- Hdmpz), 5.47 (s, 2 H, 4-H, dmpz), 6.10 (s, 2 H, 4-H, Hdmpz), 7.70
3
(t, 3JH,H = 7.7 Hz, 2 H, 5-H), 8.33 (d, JH6,H5 = 7.7 Hz, 2 H, 6-H),
(Hdmpz)2] [R = m-NO2 (3a), p-N(CH3)2 (3b), p-NH2 (3c),
3
8.40 (d, JH4,H5 = 7.7 Hz, 2 H, 4-H), 8.80 (s, 2 H, 2-H), 13.78 (s, 2
p-OCH3 (3d), p-OH (3e)]. In the complexes 3a–3e, the H
H, N-H, Hdmpz) ppm.
atoms of the terminal Hdmpz groups can be replaced by
Ag+ to give [Pd2Ag2(µ-dmpz)4(µ-O2CC6H4-R-κO)2-
[Pd2(µ-dmpz)2{O2CC6H4N(CH3)2-κO}2(Hdmpz)2] (3b): Prepared
similarly to 3a from B (0.3000 g, 0.382 mmol) and p-dimethylami-
nobenzoic acid (0.1262 g, 0.764 mmol). Addition of methanol
(7 mL) to the residue gave 3b (0.2904 g, 82%). C38H50N10O4Pd2
(923.68): calcd. C 49.41, H 5.46, N 15.16; found C 49.15, H 5.45,
(Hdmpz)2] [R = m-NO2 (4a), p-N(CH3)2 (4b), p-NH2 (4c),
p-OCH3 (4d), p-OH (4e)], keeping the carboxylate groups
in a transoid conformation. Compounds 4a–4e isomerise in
acetone solution at room temperature to the cisoid species
4aЈ–4eЈ.
N 15.17. IR: ν
= 1609 cm–1 (vs), 1589 (s), 1543 (s), 1525 (s),
˜
max
1356 (vs), 1307 (s), 1230 (m), 1194 (vs), 1140 (m), 1063 (m), 946
1
(m), 837 (m), 810 (m), 778 (vs). H NMR (300 MHz, [D6]DMSO,
23 °C): δ = 1.83 (s, 6 H, CH3, dmpz), 2.25 (s, 6 H, CH3, Hdmpz),
2.30 (s, 6 H, CH3, dmpz), 2.78 (s, 6 H, CH3, Hdmpz), 2.92 (s, 12
H, NMe2), 5.45 (s, 2 H, 4-H, dmpz), 6.07 (s, 2 H, 4-H, Hdmpz),
Experimental Section
General Procedures and Materials: [Pd2(µ-dmpz)2(dmpz)2-
(Hdmpz)2][14] and [Pd(dmpz)2(Hdmpz)2][13] were prepared as de-
scribed elsewhere. All reagents were commercially available and
used as received from Aldrich. Elemental analyses were performed
with a Perkin–Elmer 240-B microanalyser. IR spectra were re-
corded with a Perkin–Elmer 599 spectrophotometer (Nujol mulls
between polyethylene plates in the range 400–4000 cm–1). NMR
spectra were recorded with a Varian Unity-300 spectrometer using
standard references.
3
6.65 (d, JH2,H3 = JH5,H6 = 8.8 Hz, 4 H, 3-H, 5-H), 7.71 (d, 3JH2,H3
= JH5,H6 = 8.8 Hz, 4 H, 2-H, 6-H), 14.00 (s, 2 H, N-H, Hdmpz)
ppm.
[Pd2(µ-dmpz)2(O2CC6H4NH2-κO)2(Hdmpz)2] (3c): Prepared simi-
larly to 3a from B (0.2027 g, 0.258 mmol) and p-aminobenzoic acid
(0.071 g, 0.516 mmol). Yield: 0.2017 g (90%). C34H42N10O4Pd2
(867.58): calcd. C 47.07, H 4.88, N 16.14; found C 46.76, H 4.72,
N 15.83. IR: ν
= 3386 cm–1 (m), 3329 (m), 3176 (m), 3125 (m),
˜
max
1642 (m), 1600 (vs), 1548 (m), 1513 (m), 1376 (vs), 1297 (s), 1174
(s), 1066 (m), 849 (m), 813 (m), 782 (m), 649 (m), 505 (m). 1H NMR
(300 MHz, [D6]acetone, 23 °C): δ = 1.94 (s, 6 H, CH3, dmpz), 2.36
(s, 12 H, CH3, dmpz, Hdmpz), 2.89 (s, 6 H, CH3, Hdmpz), 4.98 (s,
4 H, NH2), 5.41 (s, 2 H, 4-H, dmpz), 6.00 (s, 2 H, 4-H, Hdmpz),
6.60 (m, 4 H, 3-H, 5-H), 7.77 (m, 4 H, 2-H, 6-H), 14.34 (s, 2 H,
N-H, Hdmpz) ppm.
[Pd(Hdmpz)4](O2CCH2NHCOCH3)2 (1): N-acetylglycine (0.12 g,
1.0227 mmol) was added to a solution of [Pd(dmpz)2(Hdmpz)2] (A;
0.250 g, 0.5113 mmol) in CH2Cl2/MeOH (25:5 mL). The mixture
was stirred at room temperature for 2 h and then the solvent was
evaporated to dryness. Addition of Et2O (5 mL) to the residue
yielded 1 (0.3436 g, 93%). C28H44N10O6Pd (723.12): calcd. C 46.51,
H 6.13, N 19.36; found C 46.63, H 5.90, N 19.07. IR: νmax = 3450–
˜
3000 cm–1 (s, br), 1667 (m), 1628 (vs), 1583 (s), 1376 (s), 1287 (s),
1068 (m), 1035 (m), 783 (m, sh), 650 (m), 597 (m), 555 (m), 517
(m).
[Pd2(µ-dmpz)2(O2CC6H4OCH3-κO)2(Hdmpz)2] (3d): Prepared simi-
larly to 3a from B (0.2995 g, 0.381 mmol) and p-methoxybenzoic
acid (0.1161 g, 0.763 mmol). The addition of methanol (8 mL) to
the residue gave 3d as
a yellow solid (0.2165 g, 63%).
[Pd2(µ-dmpz)2(O2CCH2NHCOCH3)2(Hdmpz)2] (2): A solution of
N-acetylglycine (0.06 g, 0.51 mmol) in methanol (10 mL) was
C36H44N8O6Pd2 (897.60): calcd. C 48.17, H 4.94, N 12.48; found
C 47.87, H 4.82, N 12.35. IR: νmax = 1609 cm–1 (vs), 1586 (s), 1570
˜
added to
a solution of [Pd2(µ-dmpz)2(dmpz)2(Hdmpz)2] (B;
(s), 1533 (s), 1509 (s), 1364 (vs), 1305 (s), 1253 (s), 1168 (s), 1031
(s), 851 (m), 819 (m), 778 (s). 1H NMR (300 MHz, [D6]acetone,
23 °C): δ = 1.94 (s, 6 H, CH3, dmpz), 2.35 (s, 6 H, CH3, Hdmpz),
2.36 (s, 6 H, CH3, dmpz), 2.89 (s, 6 H, CH3, Hdmpz), 3.81 (s, 6 H,
OCH3), 5.42 (s, 2 H, 4-H, dmpz), 6.02 (s, 2 H, 4-H, Hdmpz), 6.91
0.200 g, 0.2546 mmol) in CH2Cl2 (50 mL). The mixture was stirred
at room temperature for 2 h and the solution was then filtered
through celite and the solvent evaporated to dryness. Addition of
Et2O (5 mL) to the residue yielded
C28H42N10O6Pd2 (721.11): calcd. C 40.64, H 5.12, N 16.92; found
C 40.71, H 5.08, N 16.60. IR: ν
= 3450–3000 cm–1 (s, br), 1627
2
(0.110 g, 51%).
3
3
(d, JH2,H3 = JH5,H6 = 8.8 Hz, 4 H, 3-H, 5-H), 7.97 (d, JH2,H3
=
˜
max
JH5,H6 = 8.8 Hz, 4 H, 2-H, 6-H), 14.16 (s, 2 H, N-H, Hdmpz) ppm.
(vs), 1583 (vs), 1376 (s), 1282 (s), 1175 (m), 1035 (m), 814 (m), 775
(m), 660 (w). 1H NMR (300 MHz, CDCl3, 23 °C): δ = 1.80 (s, 6
H, CH3, dmpz), 1.86 (s, 6 H, CH3, N-acetylglycine), 2,18 (s, 6 H,
CH3, Hdmpz), 2.26 (s, 6 H, CH3, dmpz), 2.64 (s, 6 H, CH3,
[Pd2(µ-dmpz)2(O2CC6H4OH-κO)2(Hdmpz)2] (3e): Prepared simi-
larly to 3a from B (0.2120 g, 0.269 mmol) and p-hydroxybenzoic
acid
C34H40N8O6Pd2 (869.54): calcd. C 46.96, H 4.60, N 12.89; found
C 47.23, H 5.00, N 12.93. IR: ν
= 3331 cm–1 (m), 1610 (vs),
(0.0745 g,
0.539 mmol).
Yield:
0.2211 g
(94%).
2
Hdmpz), 3.74 (νA, JH,H = 4.0 Hz, 2 H, CH2, acetylglycine), 3.76
(νB, 2 H, CH2, acetylglycine), 5.41 (s, 2 H, 4-H, dmpz), 5.80 (s, 2
H, 4-H, Hdmpz), 5.99 (s, 2 H, N-H, acetylglycine), 13.07 (s, 2 H,
N-H, Hdmpz) ppm.
˜
max
1597 (vs), 1537 (vs), 1503 (vs), 1377 (vs), 1288 (vs), 1234 (vs), 1167
(vs), 1054 (m), 857 (m), 788 (s), 777 (s), 651 (m). 1H NMR
(300 MHz, [D6]acetone, 23 °C): δ = 1.94 (s, 6 H, CH3, dmpz), 2.35
(s, 12 H, CH3, dmpz, Hdmpz), 2.88 (s, 6 H, CH3, Hdmpz), 5.42 (s,
[Pd2(µ-dmpz)2(O2CC6H4NO2-κO)2(Hdmpz)2] (3a): A solution of m-
nitrobenzoic acid (0.1067 g, 0.638 mmol) in methanol (3 mL) was
954
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Eur. J. Inorg. Chem. 2006, 948–957

Reactivity of Pyrazolatopalladium() Complexes towards Carboxylic Acids
FULL PAPER
3
2 H, 4-H, dmpz), 6.00 (s, 2 H, 4-H, Hdmpz), 6.80 (d, JH2,H3
=
[s, 6 H, CH3, Pd2(µ-dmpz)2], 2.63 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2],
3.92 (s, 4 H, NH2), 5.60 [s, 1 H, 4-H, Pd2(µ-dmpz)2], 5.63 [s, 1 H,
JH5,H6 = 8.4 Hz, 4 H, 3-H, 5-H), 7.89 (d, 3JH2,H3 = JH5,H6 = 8.4 Hz,
4 H, 2-H, 6-H), 14.19 (s, 2 H, N-H, Hdmpz) ppm.
4-H, Pd2(µ-dmpz)2], 5.81 [s, 2 H, 4-H, Pd2Ag(µ-dmpz)2], 6.60 (d,
3
3JH2,H3
=
3JH5,H6 = 8.4 Hz, 4 H, 3-H, 5-H), 7.75 (d, JH2,H3
=
[Pd2Ag2(µ-dmpz)4(O2CC6H4NO2-κO)2] (4a): AgClO4 (0.0663 g,
0.3198 mmol) and NEt3 (0.5 mL) were added to a solution of 3a
(0.1412 g, 0.152 mmol) in acetone (12 mL). The resulting solution
was stirred for 75 min and then filtered through celite to eliminate
some impurities. The solution was evaporated to dryness and
MeOH (15 mL) added to the residue. The yellow solid was filtered
and washed with diethyl ether (6 mL). Yield of 4a: (0.165 g, 74%).
C34H36Ag2N10O8Pd2 (1141.3): calcd. C 35.78, H 3.18, N 12.27;
3JH5,H6 = 8.4 Hz, 4 H, 2-H, 6-H) ppm.
[Pd2Ag2(µ-dmpz)4(O2CC6H4OCH3-κO)2] (4d): Prepared similarly
to 4a from 3d (0.1810 g, 0.202 mmol), AgClO4 (0.0836 g,
0.403 mmol) and NEt3 (0.7 mL). Yield of 4d: 0.165 g (74%).
C36H42Ag2N8O6Pd2 (1111.3): calcd. C 38.91, H 3.81, N 10.08;
found C 38.91, H 3.78, N 10.03. IR: νmax = 1610 cm–1 (s), 1591 (s),
˜
1546 (s), 1378 (s), 1260 (s), 1171 (m), 1032 (m), 848 (m), 778 (s), 765
1
found C 35.58, H 2.95, N 12.08. IR: ν
= 1598 cm–1 (vs), 1564 (m), 642 (m), 628 (m). H NMR (300 MHz, [D6]DMSO, 23 °C): δ
˜
max
(vs), 1399 (vs), 1349 (vs), 1160 (m), 1081 (m), 1050 (m), 780 (m), = 2.02 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.24 [s, 6 H, CH3, Pd2Ag(µ-
654 (w). 1H NMR (300 MHz, [D6]acetone, 23 °C): δ = 2.17 [s, 6 H,
CH3, Pd2(µ-dmpz)2], 2.52 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 2.60 [s,
6 H, CH3, Pd2(µ-dmpz)2], 2.85 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 5.64
dmpz)2], 2.47 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.60 [s, 6 H, CH3,
Pd2Ag(µ-dmpz)2], 3.91 (s, 6 H, OCH3), 5.70 [s, 2 H, 4-H, Pd2(µ-
3
dmpz)2], 5.83 [s, 2 H, 4-H, Pd2Ag(µ-dmpz)2], 7.09 (d, JH2,H3
=
[s, 2 H, 4-H, Pd2(µ-dmpz)2], 5.74 [s, 2 H, 4-H, Pd2Ag(µ-dmpz)2], JH5,H6 = 9.1 Hz, 4 H, 3-H, 5-H), 7.99 (d, 3JH2,H3 = JH5,H6 = 9.1 Hz,
7.80 (m, 2 H, 5-H), 8.43 (m, 4 H, 4-H, 6-H), 8.80 (m, 2 H, 2- 4 H, 2-H, 6-H) ppm. Slow evaporation of a solution of 4d in ace-
H) ppm. Slow evaporation of a solution of 4a in acetone at room
tone at room temperature gave 4dЈ. 1H NMR (300 MHz, [D6]
DMSO, 23 °C): δ = 1.77 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.18 [s, 6 H,
1
temperature gave 4aЈ. H NMR (300 MHz, [D6]acetone, 23 °C): δ
= 1.90 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.22 [s, 6 H, CH3, Pd2Ag(µ- CH3, Pd2Ag(µ-dmpz)2], 2.46 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.59 [s,
dmpz)2], 2.58 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.66 [s, 6 H, CH3,
Pd2Ag(µ-dmpz)2], 5.62 [s, 1 H, 4-H, Pd2(µ-dmpz)2], 5.64 [s, 1 H, 4-
H, Pd2(µ-dmpz)2],5.86 [s, 2 H, 4-H, Pd2Ag(µ-dmpz)2], 7.75 (m, 2
6 H, CH3, Pd2Ag(µ-dmpz)2], 3.80 (s, 6 H, OCH3), 5.59 [s, 1 H, 4-
H, Pd2(µ-dmpz)2], 5.60 [s, 1 H, 4-H, Pd2(µ-dmpz)2], 5.83 [s, 2 H, 4-
3
3
H, Pd2Ag(µ-dmpz)2], 6.94 (d, JH2,H3 = JH5,H6 = 8.7 Hz, 4 H, 3-
3
4
4
3
3
H, 5-H), 8.37 (ddd, JH4,H5 = 8.2, JH4,H2 = 2.4, JH4,H6 = 1.2 Hz,
H, 5-H), 7.89 (d, JH2,H3 = JH5,H6 = 8.7 Hz, 4 H, 2-H, 6-H) ppm.
4
2 H, 4-H), 8.41 (dt, 3JH6,H5 = 7.8, JH6,H4 = 4JH6,H2 = 1.2 Hz, 2 H,
[Pd2Ag2(µ-dmpz)4(O2CC6H4OH-κO)2] (4e): Prepared similarly to
4a from 3e (0.17 g, 0.196 mmol), AgClO4 (0.0812 g, 0.392 mmol)
and NEt3 (0.75 mL). Yield of 4e: 0.08 g (38%). C34H38Ag2N8O6Pd2
(1083.3): calcd. C 37.70, H 3.53, N 10.34; found C 37.39, H 3.16,
6-H), 8.77 (m, 2 H, 2-H) ppm.
[Pd2Ag2(µ-dmpz)4{O2CC6H4N(CH3)2-κO}2] (4b): Prepared simi-
larly to 4a from 3b (0.2001 g, 0.202 mmol), AgClO4 (0.0893 g,
0.431 mmol) and NEt3 (0.7 mL). Yield of 4b: 0.1753 g (79%).
C38H48Ag2N10O4Pd2 (1137.4): calcd. C 40.06, H 4.24, N 12.29;
N 10.51. IR: νmax = 3606 cm–1 (m), 1610 (m), 1594 (s), 1538 (s, sh),
˜
1377 (s), 1274 (m), 1236 (m), 1166 (m), 1095 (m), 848 (m), 780 (s),
found C 40.41, H 4.41, N 11.99. IR: ν
= 1603 cm–1 (m), 1566 768 (s), 643 (m). 1H NMR (300 MHz, [D6]acetone, 23 °C): δ = 2.04
˜
max
(m), 1512 (m), 1379 (s), 1366 (m), 1196 (m), 779 (m). 1H NMR [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.16 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2],
(300 MHz, CH2Cl2, 23 °C): δ = 2.04 [s, 6 H, CH3, Pd2(µ-dmpz)2],
2.21 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 2.51 [s, 6 H, CH3, Pd2(µ-
dmpz)2], 2.53 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 3.02 (s, 12 H, NMe2),
5.61 [s, 2 H, 4-H, Pd2(µ-dmpz)2], 5.73 [s, 2 H, 4-H, Pd2Ag(µ-dmpz)
2.51 [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.57 [s, 6 H, CH3, Pd2Ag(µ-
dmpz)2], 5.60 [s, 2 H, 4-H, Pd2(µ-dmpz)2], 5.72 [s, 2 H, 4-H,
3
Pd2Ag(µ-dmpz)2], 6.87 (d, JH2,H3 = JH5,H6 = 8.9 Hz, 4 H, 3-H, 5-
3
H), 7.93 (d, JH2,H3 = JH5,H6 = 8.9 Hz, 4 H, 2-H, 6-H) ppm. Slow
3
2], 6.63 (d, JH2,H3 = JH5,H6 = 9.1 Hz, 4 H, 3-H, 5-H), 7.87 (d,
evaporation of a solution of 4e in acetone at room temperature
gave 4eЈ. 1H NMR (300 MHz, [D6]acetone, 23 °C): δ = 1.88 [s, 6
H, CH3, Pd2(µ-dmpz)2], 2.21 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 2.57
3JH2,H3 = JH5,H6 = 9.1 Hz, 4 H, 2-H, 6-H) ppm. Slow evaporation
of a solution of 4b in acetone at room temperature gave 4bЈ. 1H
NMR (300 MHz, CD2Cl2, 23 °C): δ = 1.89 [s, 6 H, CH3, Pd2(µ- [s, 6 H, CH3, Pd2(µ-dmpz)2], 2.64 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2],
dmpz)2], 2.25 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 2.59 [s, 12 H, CH3, 5.61 [s, 1 H, 4-H, Pd2(µ-dmpz)2], 5.64 [s, 1 H, 4-H, Pd2(µ-dmpz)2],
3
Pd2(µ-dmpz)2, Pd2Ag(µ-dmpz)2], 3.02 (s, 12 H, NMe2), 5.62 [s, 1 5.83 [s, 2 H, 4-H, Pd2Ag(µ-dmpz)2], 6.82 (d, JH2,H3
= =
3JH5,H6
3
3
H, 4-H, Pd2(µ-dmpz)2], 5.71 [s, 1 H, 4-H, Pd2(µ-dmpz)2], 5.82 [s, 2 8.9 Hz, 4 H, 3-H, 5-H), 7.89 (d, JH2,H3 = JH5,H6 = 8.7 Hz, 4 H,
3
H, 4-H, Pd2Ag(µ-dmpz)2], 6.63 (d, JH2,H3
=
3JH5,H6 = 8.9 Hz, 4
2-H, 6-H) ppm.
3
3
H, 3-H, 5-H), 7.86 (d, JH2,H3 = JH5,H6 = 8.9 Hz, 4 H, 2-H, 6-H)
X-ray Structure Determination: Crystal data and other details of
the structure analysis are presented in Table 5. Single crystals of 1
ppm.
[Pd2Ag2(µ-dmpz)4(O2CC6H4NH2-κO)2] (4c): Prepared similarly to were obtained by slow diffusion of n-hexane into a solution of 1 in
4a from 3c (0.08 g, 0.0922 mmol), AgClO4 (0.0382 g, 0.1844 mmol) chloroform at room temperature. Single crystals of 3d and 3e were
and NEt3 (0.5 mL). Yield of 4c: 0.009 g (9%). C34H40Ag2N10O4Pd2 obtained by slow diffusion of n-hexane into their respective solu-
(1081.3): calcd. C 37.77, H 3.73, N 12.95; found C 37.68, H 3.67, tions in acetone at room temperature. Single crystals of 4dЈ were
N 12.65. IR: ν
= 3363 cm–1 (m), 1619(m), 1602 (m), 1584 (s), obtained by slow diffusion of diethyl ether into a solution of 4d in
˜
max
1523 (m, sh), 1377 (s), 1299 (m), 1176 (m), 841 (w), 776 (m), 641
(w), 500 (w). H NMR (300 MHz, CDCl3, 23 °C): δ = 2.02 [s, 6 H, molecule was found to be disordered over two sets of positions that
DMSO at room temperature. For 3d·Me2CO, the acetone solvent
1
CH3, Pd2(µ-dmpz)2], 2.16 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 2.47 [s,
6 H, CH3, Pd2(µ-dmpz)2], 2.49 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 3.92
were refined with partial occupancy 0.50:0.50. A common set of
anisotropic parameters was used for each pair of homologous
(s, 4 H, NH2), 5.30 [s, 2 H, 4-H, Pd2(µ-dmpz)2], 5.55 [s, 2 H, 4-H, atoms. For 3e·2Me2CO, one of the acetone solvent molecules was
3
Pd2Ag(µ-dmpz)2], 6.58 (d, JH2,H3 = JH5,H6 = 8.4 Hz, 4 H, 3-H, 5-
modelled as disordered over two positions with partial occupancy
0.75:0.25, with the central C atom (C38) being common for the two
sets. For 4dЈ·0.7Me2SO, the sulfur atom of the Me2SO molecule
coordinated to Ag(1) was disordered over two positions [S(1)/S(1Ј)]
refined with partial occupancy 0.80:0.20. For this molecule, all the
3
H), 7.81 (d, JH2,H3 = JH5,H6 = 8.4 Hz, 4 H, 2-H, 6-H) ppm. Slow
evaporation of a solution of 4c in acetone at room temperature
gave 4cЈ. 1H NMR (300 MHz, [D6]acetone, 23 °C): δ = 1.87 [s, 6
H, CH3, Pd2(µ-dmpz)2], 2.21 [s, 6 H, CH3, Pd2Ag(µ-dmpz)2], 2.57
Eur. J. Inorg. Chem. 2006, 948–957
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
955

I. Ara, J. Forniés, R. Lasheras, A. Martín, V. Sicilia
Table 5. Crystal data and structure refinement for complexes 1, 3d·Me2CO, 3e·2Me2CO and 4dЈ·0.7Me2SO.
FULL PAPER
Complex
1
3d·Me2CO
3e·2Me2CO
4dЈ·0.7Me2SO
Empirical formula
Formula mass
T [K]
C28H44N10O6Pd
723.13
150(1)
C36H44N8O6Pd2·Me2CO
955.67
173(1)
C34H40N8O6Pd2·2Me2CO
985.7
100(1)
C38H48Ag2N8O7Pd2S·0.7Me2SO
1244.13
173(1)
λ [Å]
0.71073
monoclinic
P21/n
8.3462(6)
9.4493(5)
20.7037(15)
90
0.71073
monoclinic
P21/n
8.5194(6)
22.1527(15)
22.9327(16)
90
0.71073
monoclinic
Cc
17.8303(7)
12.8679(5)
20.9510(9)
90
0.71073
triclinic
P1
12.867(5)
13.823(5)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
¯
14.585(5)
99.922(7)
α [°]
β [°]
95.491(10)
90
1625.32(19)
2
1.478
0.628
96.938(1)
90
4614.5(5)
4
1.477
0.892
2.01–25.03
32062
113.957(1)
90
4392.8(3)
4
1.490
0.877
2.02–28.47
19098
101.816(8)
100.341(6)
2438.3(15)
2
1.695
1.643
γ [°]
V [Å3]
Z
Dc [gcm–3
]
µ (Mo-Kα) [mm–1
θ range [°]
]
2.37–24.97
3045
1.93–25.03
13477
Data collected
Independent data (Rint
)
2835 (0.0222)
1.050
7570 (0.0336)
1.010
R1 = 0.0305; wR2 = 0.0687
R1 = 0.0374; wR2 = 0.0710
9547 (0.0232)
1.030
R1 = 0.0230; wR2 = 0.0583
R1 = 0.0234; wR2 = 0.0585
8529 (0.0330)
1.032
R1 = 0.0589; wR2 = 0.1344
R1 = 0.0806; wR2 = 0.1476
Goodness-of-fit on F2[a]
Final R indices [I Ͼ 2σ(I)][b] R1 = 0.0292; wR2 = 0.0722
R indices (all data)[c]
R1 = 0.0438; wR2 = 0.0782
2
2 2
2
2 2
[a] Goodness-of-fit = [Σw (Fo – Fc ) /(Nobs – Nparam)]0.5. [b] R1 = Σ(|Fo| – |Fc|)/Σ|Fo|. [c] wR2 = [Σw(Fo – Fc ) /Σw(Fo2)2]0.5
.
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Reactivity of Pyrazolatopalladium() Complexes towards Carboxylic Acids
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