Cyclopalladation of N-phenyl-4-ferrocenylmethylpyrazoles: Crystal structure of [Pd{κ2-C,N-C6H4-1-[(3,5-Me 2-C3N2)-CH2-(η5-C 5H4)Fe(η5-C5H5)] }Cl(PPh3)] · CH2Cl2

Article abstract of DOI:10.1016/j.jorganchem.2008.02.033

The synthesis and characterization of pyrazole derivatives of general formula [C₆H₄-4-R-1-{(3,5-Me₂-C₃N ₂)-CH₂-(η⁵-C₅H₄) Fe(η⁵-C₅H₅)}] [R = OMe (1a) or H (1b)] with a ferrocenylmethyl substituent are described.The study of the reactivity of compounds 1 with palladium(II) acetate has allowed the isolation of complexes (μ-AcO)₂[Pd{κ²-C,N-C₆H ₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH ₂-(η⁵-C₅H₄)Fe(η⁵-C ₅H₅)]}]₂ (2) [R = OMe (2a) or H (2b)] that contain a bidentate [C(sp², phenyl), N]^- ligand and a central Pd(μ-AcO)₂Pd unit.Furthermore, treatment of 2 with LiCl produced complexes (μ-Cl)₂[Pd{κ²-C,N-C₆H ₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH ₂-(η⁵-C₅H₄)Fe(η⁵- C₅H₅)]}]₂ (3) [R = OMe (3a) or H (3b)] that arise from the replacement of the acetato ligands by the Cl^-.Compounds 2 and 3 also react with PPh₃ giving the monomeric complexes [Pd{κ²-C,N-C₆H₃-4-R-1-[(3,5-Me ₂-C₃N₂)-CH₂-(η⁵- C₅H₄)Fe(η⁵-C₅H ₅)]}X(PPh₃)] {X^- = AcO^- and R = OMe (5a) or H (5b) or X^- = Cl^- and R = OMe (6a) or H (6b)}, where the phosphine is in a cis-arrangement to the metallated carbon atom. Treatment of 3 with thallium(I) acetylacetonate produced [Pd{κ²-C,N-C₆H₃-4-R-1-[(3,5-Me ₂-C₃N₂)-CH₂-(η⁵- C₅H₄)Fe(η⁵-C₅H ₅)]}(acac)] (7) [R = OMe (7a) or H (7b)]. Electrochemical studies of the free ligands and the cyclopalladated complexes are also reported. The dimeric complexes 3 also react with MeO₂C-C{triple bond, long}C-CO₂Me (in a 1:4 molar ratio) giving [Pd{(MeO₂C-C{double bond, long}C-CO₂Me)₂C₆H₃-4-R-1-[(3 ,5-Me₂-C₃N₂)-CH₂-(η ⁵-C₅H₄)Fe(η⁵-C₅H ₅)]}Cl] (8) [R = OMe (8a) or H (8b)], which arise from the bis(insertion) of the alkyne into the σ{Pd-C(sp², phenyl)} bond of 3.

Full text of DOI:10.1016/j.jorganchem.2008.02.033

Journal of Organometallic Chemistry 693 (2008) 2119–2131
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Cyclopalladation of N-phenyl-4-ferrocenylmethylpyrazoles: Crystal
structure of [Pd{j2-C,N–C6H4-1-[(3,5-Me2–C3N2)
–CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl(PPh3)] ꢀ CH2Cl2
c
c
d
Asensio González a, Concepción López b, , Xavier Solans , Mercè Font-Bardía , Elies Molins
*
a Laboratori Química Orgánica, Facultat de Farmàcia, Universitat de Barcelona, Pl. Pius XII s/n, 08028 Barcelona, Spain
b Departament de Química Inorgànica, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
c Departament de Cristal.lografia Mineralogía i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès s/n, E-08028 Barcelona, Spain
d Institut de Ciència de Materials de Barcelona (ICMAB-CSIC). Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis and characterization of pyrazole derivatives of general formula [C6H4-4-R-1-{(3,5-Me2–
C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)}] [R = OMe (1a) or H (1b)] with a ferrocenylmethyl substituent are
described.The study of the reactivity of compounds 1 with palladium(II) acetate has allowed the isolation
of complexes (l-AcO)2[Pd{j2-C,N-C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}]2 (2)
[R = OMe (2a) or H (2b)] that contain a bidentate [C(sp2,phenyl),N]ꢁ ligand and a central ‘‘Pd(l-AcO)2Pd”
unit.Furthermore, treatment of 2 with LiCl produced complexes (l-Cl)2[Pd{j2-C,N-C6H3-4-R-1-[(3,5-Me2–
C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}]2 (3) [R = OMe (3a) or H (3b)] that arise from the replacement of the
acetato ligands by the Clꢁ.Compounds 2 and 3 also react with PPh3 giving the monomeric complexes
[Pd{j2-C,N-C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}X(PPh3)] {Xꢁ = AcOꢁ and R = OMe
(5a) or H (5b) or Xꢁ = Clꢁ and R = OMe (6a) or H (6b)}, where the phosphine is in a cis-arrangement to
the metallated carbon atom. Treatment of 3 with thallium(I) acetylacetonate produced [Pd{j2-C,N-
C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}(acac)] (7) [R = OMe (7a) or H (7b)]. Electro-
chemical studies of the free ligands and the cyclopalladated complexes are also reported. The dimeric
complexes 3 also react with MeO2C–C„C–CO2Me (in a 1:4 molar ratio) giving [Pd{(MeO2C–C@C–
CO2Me)2C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl] (8) [R = OMe (8a) or H (8b)], which
arise from the bis(insertion) of the alkyne into the r{Pd–C(sp2,phenyl)} bond of 3.
Received 15 January 2008
Received in revised form 22 February 2008
Accepted 22 February 2008
Available online 10 March 2008
Keywords:
Cyclopalladation
Ferrocene derivatives
Alkyne insertios
Palladacycles
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
On the other hand, ferrocene derivatives containing heterocy-
clic systems have attracted great interest in recent years
An important area of organometallic chemistry is that focused
on cyclopalladated complexes. Interest in such compounds has
increased exponentially due to their physical and/or chemical
properties or their applications in different areas [1–6]. Metallo-
mesogens [1c] and antitumor drugs containing palladacycles [3]
have been reported. The use of chiral cyclopalladated complexes
for the determination of enantiomeric excesses of chiral reagents
has also been described [1d]. More recently, examples of their util-
ity in homogeneous catalysis or as building blocks in macromolec-
ular chemistry have also been published [4,6g,6h]. In addition, the
high reactivity of the Pd–C bond in this sort of compounds makes
them valuable precursors in organic synthesis [1e,1f,5,6b] includ-
ing the total synthesis of natural products [1e,1f,1g,5d,6b].
[5d,6d,6g,6h,6i–8] because of their physical or chemical physical
properties as well as for their applications in a wide variety of areas
including homogeneous catalysis [5d,6h,6i] and Bio-Medicine [8]. In
this sort of compounds, the presence of a heterocycle with one or
more atoms with good donor abilities is especially relevant in view
to their use as ligands for transition metals to give heteropolyme-
tallic complexes [6g,9,10] in which the existence of two or more
metal ions in close vicinity may induce a co-operative effect.
Among all the examples reported so far, those containing oxazoline
or oxazine rings (Fig. 1A and B) and palladium(II) are specially rel-
evant for different reasons [6g,6h,9]. This type of ligands exhibit an
interesting, and sometimes unexpected, coordination modes to-
ward palladium(II). For instance, the reaction of the 4-ferrocenyl-
1,3-oxazolines shown in Fig. 1A with palladium(II) acetate gave
the unexpected transannular metallation of the non-substituted
ring of the ferrocenyl unit giving the pentametallic complex de-
picted in Fig. 1C [6h].
* Corresponding author.
E-mail address: conchi.lopez@qi.ub.es (C. López).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.02.033

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A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
Fig. 1. Ferrocenyl ligands containing oxazoline and oxazine rings (A and B) used previously in the cyclopalladation reaction together with the chemical formulae of some of
their palladated derivatives (C and D).
These transition metal complexes may also present interesting
electrochemical properties. For instance, electrochemical studies
of the tetrametallic complex [Pd{(g5-C5H3)–CH@N–(C6H4–
2CH2O)}] (Fig. 1D), formed by cyclopalladation of the 2-ferroce-
nyl-2,4-dihydro-1H-3,1-benzoxazine (Fig. 1B) have shown that
the central ‘‘Pd(l-O)2Pd” moiety allows electronic communication
between two iron(II) centres [6g]. However, and despite of the
increasing interest on palladium(II) complexes with ligands con-
taining simultaneously a ferrocenyl unit and a (N,O) or (N,S) het-
erocycle [6g,6h,6i,6j,9,10] parallel studies on related compounds
with azole rings are scarce [6i,11] and only one of them refers to
palladium(II) complexes containing simultaneously a bidentate
[C,N(pyrazole)]ꢁ ligand and a ferrocenyl unit [6i].
In view of these facts, we focused our attention on the synthesis
of novel ferrocene derivatives containing pyrazolyl units and to
study their reactivity towards transition metals. In this work, we
present the syntheses and characterization of compounds [C6H4-
4-R-1-{(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)}] (1) [with
R = OMe (1a) or H (1b)] (Fig. 2), that contain a N-phenyl substituted
pyrazolyl group in the pendant arm of the ferrocene. The study of
their reactivity to palladium(II) acetate and a preliminary account
of the reactivity of the palladium(II) complexes obtained with di-
methyl acetylenedicarboxylate is also reported.
2. Results and discussion
2.1. The ligands
Compounds 1 were prepared from pentane-2,4-dione using a
straightforward two-step procedure (Scheme 1). First, 3-ferroce-
nylmethyl-pentane-2,4-dione was obtained by electrophilic cou-
pling on position 3 of the diketone using ferrocenylmethanol in a
two-phase dichloromethane/40% aqueous tetrafluoroboric acid
mixture [12]. Subsequent treatment with either 4-methoxyphenyl-
hydrazine or phenylhydrazine at 120 °C [13] followed by the puri-
fication of the crude product of the reaction by column
chromatography gave the pyrazole-containing ferrocenyl ligands
in good yields [84% (for 1a) and 95% (for 1b)].
Ligands 1 were characterized by elemental analyses, mass spec-
trometry, infrared spectra and mono- and two-dimensional NMR
experiments. The elemental analyses (Section 3) were consistent
with the proposed formulae and their mass spectra showed a peak
at m/z = 401 (for 1a) or at 371 (for 1b) that agree with the values
expected for the cations {[M]+H}+.
Proton-NMR spectra of 1 showed the typical pattern of mono-
substituted ferrocene derivatives [6d,6g,14,15]. It consists of a
group of three signals of relative intensities 5:2:2 in the range
4.00–4.20 ppm which are assigned to protons of the C5H5 moiety
and to the pairs of protons (H2 and H5) and (H3 and H4) of the other
ring. The resonances arising from the methylenic protons appeared
as a singlet at around 3.50 ppm. The two additional singlets, at
2.15 ppm < d < 2.30 ppm, were assigned to methyl groups of the
heterocycle. The singlet at higher fields showed NOE peaks with
Fig. 2. New ferrocenyl ligands (1a and 1b) containing pyrazolyl units under study.

A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
2121
Scheme 1.
those from the –CH2– unit and with the proton on the ortho site
(H600) of the aromatic ring. This coupling is only possible for the
particular [6g,6h,14,16] we also undertook electrochemical studies
on ligands 1. Electrochemical data were obtained by cyclic voltam-
metric studies of freshly prepared solutions (10ꢁ3 M) in acetoni-
trile using (Bu4N)[PF6] as supporting electrolyte. The cyclic
voltammograms of 1 (Fig. 3) showed an anodic peak with a directly
associated reduction peak in the reverse scan and for the two li-
gands the positions of these peaks (Table 1) are very similar [the
differences do not exceed 3r (r = 5 mV)]. Since 1a and 1b differ
in the nature of the substituent on the meta-position of the phenyl
ring, which is far away from the ferrocenyl unit, the replacement of
the OMe (in 1a) by the hydrogen (in 1b) is not expected to produce
significant variations on the electronic environment of the iron(II).
In both cases the DE parameter departs appreciably from the value
of 59 mV (theoretically expected for a one electron-step oxidation–
reduction process [17]), suggesting that a structural reorganization
takes place on oxidation.
Previous electrochemical studies of ferrocene derivatives have
shown that the presence of electron-withdrawing groups inhibits
the oxidation of the iron(II) while the electron–donor substituents
facilitate the oxidation [18,19]. For 1, the position of the anodic
peaks appears at slightly higher potentials than for ferrocene. This
characteristic indicates that the substituent ‘‘C6H3-4-R-1-[(3,5-
Me2–C3N2)–CH2–” is slightly more electron-donating that the
hydrogen in ferrocene.
methyl group bound to the C5 carbon of the pyrazolyl unit
0
(Meb). Two doublets and one triplet (for 1a) or a triplet and a broad
multiplet (for 1b) arising from the protons of the phenyl ring were
also observed in the low field region of the spectra. The resonance
of the protons of the OMe unit of 1a appeared as a singlet at
3.81 ppm.
The assignment of the signals observed in 13C{1H} NMR spectra
of 1 (Section 3) was carried out with the aid of two-dimensional
{1H–13C} HSQC and HMBC experiments. The resonances corre-
sponding to the quaternary carbon nuclei of 1 were easily detected
by comparison of the signals detected in the 13C{1H} and in the
HSQC spectra. The analyses of the cross-peaks, detected in the
HMBC spectra, between the signal of the –CH2– protons allowed
to assign the resonances of the ipso carbon of the ferrocenyl unit
(C1) and of the C4 nuclei. The singlet of the Meb protons also
0
showed two cross-peaks with the quaternary carbon atoms C4
0
5
0
a
(previously identified) and C ; while the Me protons correlated
with the C3 and C4 atoms.
0
0
As a result of the increasing interest in the electrochemistry of
organometallic compounds [16] and of ferrocene derivatives in
Another interesting feature arises from the comparison of the
electrochemical behaviour of 1 and other ferrocene derivatives
with azole groups, such as 4-ferrocenylpyrazol (1c) or 4-ferroce-
nyl-1-tritylpyrazol (1d), ferrocenyltriazole (1e), or ferrocenyltet-
razole (1f), depicted in Fig. 4 [20a,20b]. The comparison of the
half-wave potentials {E1/2} for 1a, 1b, 1c (E1/2 = ꢁ30 mV [20a])
and 1d (E1/2 = ꢁ40 mV [20a]) reveals that the incorporation of
the –CH2– moiety between the ferrocenyl ligand and the pyrazole
ring reduces the proclivity of the iron(II) to oxidize, but this effect
is smaller than for the systems containing tri- or tetrazole units (1c
and 1d, with E1/2 = 0.21 and 0.27 V, respectively) [20b].
Table 1
Summary of electrochemical data [anodic and cathodic potentials (Epa and Epc
,
respectively, referred to the ferrocene/ferricinium couple) and separation between
peaks (DE) in mV] for ligands 1a and 1b and for their cyclopalladated complexes:
[Pd{C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl(PPh3)]
[Pd{C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}(acac)] (7)
(6)
and
Compound
R
Epa
Epc
DE
1a
1b
6a
6b
7a
7b
OMe
H
OMe
H
OMe
H
30
34
132
140
163
171
ꢁ41
ꢁ46
22
12
64
71
80
110
128
99
Fig. 3. Cyclic voltammograms of ligands 1a and 1b in acetonitrile at 298 K at a scan
speed t = 100 mV/s.
84
87

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A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
Fig. 4. Related ferrocenyl ligands containing azole units studied previously.
2.2. Palladium(II) compounds
In order to study the potential binding ability of ligands 1 to-
wards palladium(II) their reactivity with Pd(AcO)2 was studied un-
der different experimental conditions. Treatment of 1 with the
equimolar amount of Pd(AcO)2 in a mixture of glacial acetic acid
and acetic anhydride (5:1) under reflux for 3 h produced the for-
mation of large amounts of metallic palladium and a nearly black
solution. The subsequent concentration to dryness of the filtrate
and the work up of a SiO2 column gave small amounts of a bright
yellow solid [hereafter referred to as 2a or 2b (for 1a and 1b,
respectively)] (Scheme 2). Characterization data of 2 (Section 3)
were consistent with those expected for the dimeric complexes:
(l-AcO)2[Pd{j2–C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)-
Fe(g5-C5H5)]}]2 (2) [R = OMe (2a) or H (2b)] that arise from the
metallation of the phenyl ring. Unfortunately, the yields of 2 were
extremely low (20% for 2a and 16% for 2b) and clearly smaller than
those reported by Mendoza et al. [11] for the cyclometallation of 3-
Fig. 5. Organic ligands containing pyrazolyl units described by Mendoza et al. [11]
and their dinuclear cyclopalladated derivatives containing bridging acetato groups.
phenylpyrazole derivatives (Fig. 5) under identical experimental
conditions.
Scheme 2.

A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
2123
More interesting were the results obtained when these reac-
tions were performed using toluene as solvent (Scheme 2). In these
cases, and after a similar work-up, compounds 2 were isolated in
higher yields (ca. 60%). The comparison of the results obtained
from the reactions presented in Scheme 2, indicates that the opti-
mization of the synthetic method of 2 can be easily achieved by
replacement of the mixture acetic acid/acetic anhydride (5:1) by
toluene.
The infrared spectra of 2 showed two bands arising from the
symmetric and asymmetric stretchings of the carboxylato groups
at 1563 and 1431 cmꢁ1 (for 1a) or at 1576 and 1444 cmꢁ1 (for
1b). The separation between these two absorption bands sug-
gested, according to the bibliography [21], that the AcOꢁ behaved
as a (O,O0) bridging ligand.
the resonances arising from the aromatic protons of ligands 1, and
(c) a significant decrease of the intensity of the resonance due to
the carbon-13 nuclei on the ortho site of the phenyl ring (C2
)
00
and shifted downfield when compared with the free ligand. The
observations are similar to those reported for other N-donor
phenyl ligands and their cyclopalladated complexes with a r[Pd–
C(sp2, phenyl)] bond [24]. Furthermore, {1H–13C} HSQC NMR spec-
tra of 2 showed only three (for 2a) or four (for 2b) cross peaks in
the aromatic region, which is consistent with the metallation of
the aromatic ring on position 200. The assignments of the signals
of the protons and carbon nuclei of compounds 2a and 2b pre-
sented in Section 3 was carried out with the aid of the two dimen-
sional experiments: {1H–1H} NOESY and COSY and {1H–13C}
NOESY.
It is well-known that the dimeric cyclopalladated complexes
with acetato groups as bridging ligands may exhibit different iso-
meric forms [6f,22,23]. In these isomers, the two halves of the mol-
ecule could be in a cis- or trans-arrangement. It has been reported
that for the trans-isomers the resonance of the methyl groups of
the bridging ligands appear as one singlet [22,23]; but it splits into
two singlets in the cis-isomers. The 1H NMR spectra of 2 showed
only one singlet [at 2.16 (for 2a) or 2.14 ppm (for 2b)], suggesting
that in 2 the two halves are in a trans-arrangement. The high field
shift of the resonance of the methylic protons Mea of the pyrazolyl
unit is also consistent with a trans-structure [22,23]. Most of the
acetato-bridged cyclopalladated dimers described before show a
folded structure (commonly known as open-book structure) in
solution as well as in the solid state [22,23]. On this basis we as-
sumed that in 2 the relative orientation of the acetato ligands cor-
responds to the open-book type with a C2 symmetry.
We also studied the reactivity of the cyclopalladated complexes
with LiCl and triphenylphosphine (Scheme 2). The action of an ex-
cess of LiCl to acetone solutions of 2 at 298 K for 10 h produced yel-
low precipitates. These solids, that were identified as (l-Cl)2[Pd{j2-
C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}]2
(3) [R = OMe (3a) or H (3b)], arise from the substitution of the two
bridging acetato units by the chloride ligands. Elemental analyses
of 3 (Section 3) were consistent with those expected for the di-
meric products (l-Cl)2[Pd{j2-C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–
CH2–(g5-C5H4)Fe(g5-C5H5)]}]2 (3) [R = OMe (3a) or H (3b)]. Unfor-
tunately, compounds 3 are extremely insoluble in the most com-
mon solvents used for NMR studies, and this precluded their
characterization by NMR. However, the addition of a few drops
of pyridine (py-d5) to a suspension of 3a or 3b in CDCl3, produced
the complete dissolution of the palladium(II) complex and the
proton NMR spectra of the resulting bright yellow solutions sug-
gested the presence of the monomeric derivatives [Pd{j2-C,N–
C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]Cl(py-d5)]
(4) [Scheme 2].
The most relevant features detected in the 1H and 13C{1H} NMR
spectra of 2 were: (a) the absence of the signal ascribed to the pro-
ton H2 on the ortho site of the phenyl ring, (b) a high-field shift of
00
Fig. 6. ORTEP plot of the crystal structure of compound [Pd{j2-C,N-C6H4-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl(PPh3)] (6b) ꢀ 1/2CH2Cl2. The molecule of CH2Cl2
and hydrogen atoms have been omitted for clarity. Selected bond lengths (in Å) and angles (in °): Pd–C(22), 2.035(5); Pd–N(1), 2.104(4); Pd–P, 2.2683(17); Pd–Cl(1), 2.389(2);
C(10)–C(11), 1.504(6); C(11)–C(12), 1.507(5); N(1)–N(2), 1.401(4); N(1)–C(13), 1.331(5); C(12)–C(13), 1.416(6); C(12)–C(14), 1.381(6); C(14)–N(2), 1.376(5); N(2)–C(17),
1.394(5); C(17)–C(22), 1.406(6); C(17)–C(18), 1.394(5); C(18)–C(19), 1.378(6); C(19)–C(20), 1.384(7); C(20)–C(21), 1.407(6); C(21)–C(22), 1.359(6); N(1)–Pd–C(22), 79.68-
(17); C(22)–Pd–P, 95.18(14); P–Pd–Cl(1), 89.64(8); Cl(1)–Pd–N(1), 97.25(12); C(10)–C(11)–C(12), 109.6(3); C(14)–C(12)–C(11), 126.5(4); C(13)–C(12)–C(11), 126.3(4); N(1)–
C(13)–C(12), 109.4(4); N(1)–C(13)–C(15), 122.9(4); C(12)–C(13)–C(15), 127.7(4); N(2)–C(14)–C(12), 107.1(3); N(2)–C(14)–C(16), 124.3(4); C(12)–C(14)–C(16), 128.6(4),
N(2)–C(17)–C(18), 121.1(4); N(2)–C(17)–C(22), 117.0(3); N(2)–N(1)–Pd, 112.6(3), C(14)–N(2)–N(1), 109.3(3); C(14)–N(2)–C(17), 134.5(3); N(2)–N(1)–C(13), 107.2(3).

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A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
The dinuclear complexes 2 and 3 reacted with triphenylphos-
a cis-arrangement between the phosphorus and the metallated car-
bon (C200) in good agreement with the so-called transphobia effect
[27].
In order to confirm the mode of binding of the ligand in the pal-
ladium(II) complexes a crystal of 6b was grown. Unfortunately, the
quality of the crystal was poor but attempts to isolate a better crys-
tal using other precipitating agents or experimental conditions did
not succeed.
phine [in a molar ratio PPh3: (2 or 3) = 2] in CH2Cl2 at 298 K giving
the monomeric derivatives [Pd{j2-C,N–C6H3-4-R-1-[(3,5-Me2–
C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}(X)(PPh3)] [X = AcOꢁ (5) or Clꢁ
(6)] (Scheme 2). The formation of 4, 5 and 6 requires the splitting
of the central ‘‘Pd(l-X)2Pd” units of 2 (Xꢁ = AcOꢁ) or 3 (Xꢁ = Clꢁ)
and the incorporation of a molecule of deuterated pyridine (in 4)
or of PPh3 (in 5 and 6) in the coordination sphere of the palla-
dium(II). A metathesis reaction between 4 and LiCl in acetone at
298 K also gave products 6 (Scheme 2).
The crystal structure contains molecules of [Pd{j2-C,N–C6H4-1-
[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl(PPh3)] (Fig. 6) and
CH2Cl2. In the heterodimetallic molecules the palladium is bound
to the N(1) atom and the carbon {C(22)} on the ortho site of the
phenyl ring. Thus, confirming a [C(sp2,phenyl),N]ꢁ mode of bind-
ing of the ligand. The Pd–N(1) bond length [2.104(4) Å] is longer
than the single bond predicted value of 2.011 Å and the Pd–C(22)
bond distance [2.035(5) Å] falls in the range reported for related
palladacycles containing bidentate [C(sp2,phenyl),N]ꢁ ligands
[11,22].
A chloride atom and the phosphorus of the PPh3 ligand com-
plete the coordination sphere of the metal which is in a slightly-
distorted square-planar environment. The Pd–P and Pd–Cl bond
distances [2.2683(17) Å and 2.389(2) Å, respectively] are similar
to the values obtained for compounds of the type [Pd{C(sp2,phe-
nyl)},N}Cl(PPh3)] [22,24,25]. The value of the P–Pd–C(22) angle
[95.09(17)°] confirms a cis-arrangement between the metallated
carbon and the phosphine ligand, in good agreement with the
transphobia effect [27]. The angles between adjacent atoms in
Compounds 5 and 6 were characterized by elemental analyses,
mass and IR spectra and mono-[1H, 13C{1H} and 31P{1H}] and bidi-
mensional NMR studies. Elemental analyses and mass spectra of 5–
6 were consistent with the proposed formulae. The IR spectra of 5
and 6 showed the typical bands due to the coordinated PPh3 li-
gands [21,25] and for 5 the difference between the position of
the bands due to the symmetric and asymmetric stretching of
the ˜CO2– unit agreed with the values reported for palladium(II)
complexes with acetato group acting as a monodentate ligand
[21]. 31P{1H} NMR spectra of 5 and 6 showed a singlet in the range
44–45 ppm. The replacement of the acetato ligand (in 5a or 5b) by
the chloro (in 6a or 6b) produces a small downfield shift of the sig-
nal [26]. The {1H–1H} NOESY spectra of 5 and 6 showed the exis-
tence of a NOE peak between the resonance due to H3 and one
00
aromatic proton of the phosphine. Besides that in the 13C{1H}NMR
spectra the signal due to the metallated carbon (C200) appeared as a
doublet due to phosphorus coupling. These results are indicative of
Fig. 7. Schematic view of the arrangement of the heterodimetallic molecules [Pd{j2-C,N–C6H3-1-[(3,5-Me2–C3N2)–CH2–(g5–C5H4)Fe(g5-C5H5)]}Cl(PPh3)] (6b) in the crystal.
(Hydrogen atoms have been omitted for clarity).

A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
2125
the coordination sphere of palladium(II) lie in the range 79.68(17)–
95.25(12)°, the smallest angle corresponding to the metallacycle
and the largest to the N–Pd–Cl angle.
van der Waals radii of these atoms (C, 1.70 and H, 1.10 Å [28]). This
is suggests of a weak C–Hꢀ ꢀ ꢀCl interaction which connects the pairs
forming a chain (Fig. 7).
Each molecule contains a [5.5.6] tricyclic system formed by a
five-membered palladacycle, the pyrazole ring and the phenyl
group. The metallacycle, which is formed by the set of atoms [Pd,
N(1), N(2), C(17) and C(18)], is practically planar and the distance
between the palladium(II) and the iron(II) atoms (8.141 Å) ex-
cludes the existence of any direct interaction [28]. As expected
bond lengths and angles of the two ferrocenyl units are consistent
with the values reported for most ferrocene derivatives [22]. In
both cases the pentagonal rings of the ferrocenyl unit are planar,
practically parallel (tilt angle of 4.3°) and they deviate from the
ideal eclipsed conformation by 2.1(4)°.
In the crystal, two vicinal molecules are associated in a head to
tail arrangement and the separation between the phenyl ring of
one of these units and the pyrazolyl group of the unit located at
(ꢁx, 1 ꢁ y, ꢁz) is indicative of p-stacking of these cycles (Fig. 7).
In addition, the distance between the chloride of one of these mol-
ecules and the hydrogen H(31) of the phosphine ligand of another
molecule of a neighbouring couple (2.801 Å) equals the sum of the
The action of thallium(I) acetylacetonate upon acetone suspen-
sions of 3 at 298 K produced the precipitation of thallium(I) chlo-
ride and the formation of a yellow solution which gave, after
concentration, [Pd{j2–C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-
C5H4)Fe(g5-C5H5)]}(acac)] (7) [R = OMe (7a) or H (7b)] (Scheme
3). Characterization data of 7 (Section 3) agreed with the proposed
formulae. Their IR spectra showed the typical bands due to the
acetylacetonato(ꢁ1) ligand acting as a bidentate (O,O)ꢁ group
[21]. The resonances of the methyl protons of the acac ligand
(Mec and Med) appeared as two singlets in the range 1.8–2.1 ppm
and the analysis of cross-peaks detected in the 1H–1H NOESY spec-
tra suggested that the signal at higher fields was due to the Mec
protons. The differences detected in the chemical shifts of the car-
bon nuclei of the two ˜CO units can be ascribed to the different
trans-influence of the two donor atoms of the bidentate
[C(sp2,phenyl),N]ꢁ ligands [29].
In order to elucidate the effect produced by the coordination of
the palladium(II) and the nature of the ligands bound to it upon the
Scheme 3.

2126
A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
electronic environment of the iron we also studied the electro-
chemical properties of a selection of the new cyclopalladated com-
plexes using the same methodology as for the free ligands (see
above and Section 3). Unfortunately, the instability of compounds
2 in acetonitrile [30] and the low solubility of the dimeric com-
plexes 3 did not allow us to include these products in this study.
In all the remaining cases the cyclic voltammograms showed one
oxidation and one reduction peak. The electrochemical parameters
presented in Table 1, show that the binding of the palladium(II)
produces a slight decrease of the proclivity of the iron(II) to be oxi-
dized when compared with that of the corresponding free ligand in
good agreement with the results reported for related palladium(II)
complexes containing N-donor ferrocenyl ligands [6g,6h,31]. Also
in these cases the magnitude of the DE (>59 mV) suggests that a
structural reorganization takes place on oxidation. The differences
in the backbone of the ferrocenyl ligand do not affect significatively
the electrochemical behaviour of the palladium(II) compounds. In
addition, data of Table 1, reveals that the replacement of the two
monodentate ligands (Clꢁ and PPh3) (in 6) by the bidentate acetyl-
acetonato(ꢁ1) ligand (in 7) (Table 1 and Fig. 8) produces a slight
shift (of ca. 30 mV) of the wave to the more anodic region. It should
be noted that in the two pairs of compounds changes take place at
a seven-bond length distance from the iron(II) and consequently
the effect induced by the replacement of the ligands bound to
the palladium(II) ion the Fe(II) ion is expected to be weak.
dimethyl acetylenedicarboxylate. When suspensions of 3a (or 3b)
in CH2Cl2 were treated separately with MeO2C–C„C–CO2Me (in
a molar ratio alkyne: Pd(II) = 4) under reflux for 24 h a deep orange
solution was formed (Scheme 3). Further evaporation of the sol-
vent followed by a short SiO2-column chromatography using a
CH2Cl2:MeOH (100:0.1) mixture as eluant yield a yellow band that
gave after concentration to dryness orange solids (8). These prod-
ucts, that were identified as [Pd{(MeO2C–C@C–CO2Me)2(C6H3-4-
R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl] (8) [R = OMe
(8a) or H (8b), Scheme 3], arise from the bis(insertion) of the
MeO2C–C„C–CO2Me into the r[Pd–C(sp2, phenyl)] bond of 3 and
contain a [5.9.6] tricyclic system and a g3-butadienyl unit. Molar
conductivities of 10ꢁ3 M solutions of 8 in acetone were consistent
with the values expected for non-electrolytes [33]. The most rele-
vant features observed in the 1H NMR spectra of 8 is the presence
of four singlets of identical intensity in the range: 3.0–4.0 ppm. In
the HSQC spectra these signals showed cross-peaks with four sing-
lets observed in the 13C NMR spectra at 50 < d < 53 ppm. In addi-
tion, the 13C{1H} NMR spectra showed four singlets in the low-
field region that are due to the carbon atoms of the COO units.
The resonances of the central carbon of the inserted butadienyl
unit Ca–Cc appeared at lower fields and exhibited low intensity.
All these findings are similar to those reported for related pallada-
cycles arising from the bis(insertion) of alkynes in which the two
substituents close to the phenyl ring are in a trans-arrangement
while the remaining two are on a cis-arrangement. This is the typ-
ical arrangement of groups found in the majority of palladacycles
formed by a bis(insertion) process of alkynes into the r(Pd–C)
bond [34].
2.3. Study of the reactivity of the r(Pd–C) bond of 3
As mentioned above one of the main applications of palladacy-
cles is their use as precursors in organic and organometallic
synthesis [1a,1e,1f,1g,6b,6c,32]. Commonly in these processes
the first step consists on the insertion of small molecules (i.e. CO,
alkenes, alkynes or isonitriles) into the r(Pd–C) bond
[1a,1e,1f,1g,6b,6c,32]. In view of this fact and as a first attempt to
evaluate the potential utility of the new cyclopalladated complexes
prepared in this work as precursors in synthesis, we decided to
study the reactivity of the di-l-chloro derivatives (3) towards
2.4. Conclusions
The studies presented here have allowed the isolation and char-
acterization of two novel ferrocene derivatives containing pyrazolyl
units. The study of their reactivity with Pd(AcO)2 has provided con-
clusive evidence of the advantages of the use of toluene as solvent
to achieve the cyclopalladated products: (l-AcO)2[Pd{j2-C,N–C6H3-
4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}]2 (2). These
compounds were easily transformed into the dimeric derivative
(l-Cl)2[Pd{j2-C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe-
(g5-C5H5)]}]2 (3) or the mononuclear complexes [Pd{{j2-C,N–C6H3-
4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}X(PPh3)] [Xꢁ
= AcOꢁ (5) or Clꢁ (6)] and [Pd{{j2-C,N–C6H3-4-R-1-[(3,5-Me2–
C3N2)–CH2–(g5-C5H4)Fe(g5-C5H5)]}(acac)] (7).
Electrochemical studies of the ligands as well as of the selected
cyclopalladated compounds have shown that in all the new prod-
ucts the iron(II) is less prone to oxidation than in ferrocene, and
the proclivity to be oxidized increases according to the sequence
7 6 6 < 1. Besides that, for 1, 6 and 7, the change of the nature of
the substituent (OMe or H) on the phenyl ring does not introduce
significant variations in the electrochemical behaviour of these
products.
The reactions of 3 with MeO2C–C„C–CO2Me lead the neutral
palladacycles: [Pd{(MeO2C–C@C–CO2Me)2–C6H3-4-R-1-[(3,5-Me2–
C3N2)–CH2-(g5-C5H4)Fe(g5-C5H5)]}Cl] (8) that contain
a nine-
membered ring formed by the bis(insertion) of the alkyne into
the r(Pd–C) bond indicating a high reactivity of this bond. Despite
the large amount of papers centred on the study of the reactivity of
palladacycles containing bidentate (C,N)ꢁ ligands in none of the
examples reported so far the nitrogen atom belongs to an azole
ring. Thus, the results presented here constitute the first step for
further work on this field mainly centred on the insertion of other
molecules (i.e. alkynes, alkenes, isonitriles, etc.) into the r(Pd–C)
bond. In addition, since it is well-known that palladacycles arising
from the insertion of alkynes into the r(Pd–C) bond may undergo
depalladation reactions to give new organic compounds (i.e. func-
Fig. 8. Cyclic voltammograms of compounds 6a and 7a in acetonitrile at 298 K at a
scan speed t = 100 mV/s.

A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
2127
tionalized heterocycles) [1e,1f,1g,6b], compounds 8 described here
appear to be excellent candidates to be studied in this field.
lar amount of 3-ferrocenylmethyl-pentane-2,4-dione (0.792 g)
[yield: 0.953 g (95%)].
Compounds 1 were recrystallized as follows: a 200 mg amount
of 1 was dissolved in methanol (ca. 25 mL) and filtered out. Slow
evaporation of the bright yellow solution at 298 K produced the
precipitation of the desired product that was collected and air-
dried.
3. Experimental
3.1. Materials and methods
Characterization data for 1a: Anal. Calc. for C23H24N2OFe: C,
69.01; H, 6.04; N, 7.00. Found C, 68.87; H, 6.12; N, 6.88%. MS
(ESI+): 401{[M]+H}+. IR: 3080(m), 2910(m), 1588(s), 1516(s),
Acetylacetone, ferrocenylmethanol, 4-methoxyphenylhydra-
zine and phenylhydrazine, triphenylphosphine, HBF4, Pd(AcO)2,
LiCl, and thallium(I) acetylacetonate were obtained from commer-
cial sources and used as received. Solvents were distilled and dried
before use [35]. Some of the preparations require the use of thal-
lium(I) salts that should be handled with CAUTION!.
1248(s), 1176(m), 1022(m), 835(s), 813(s), 608(m), 478(m) cmꢁ1
.
1H NMR data [36]: d = 7.24 (d, 2H, J = 8.0, H2 and H600), 6.91 (d,
00
2H, J = 8.0, H3 and H500), 4.12 (s, 5H, C5H5), 4.09 (s, 2H, H and
2
00
H5), 4.03 (s, 2H, H3 and H4), 3.46 (s, 2H, –CH2–), 3.81 (s, 3H,
OMe), 2.25 (s, 3H, Mea) and 2.16 (s, 3H, Meb). 13C{1H} NMR data
Elemental analyses were carried out at the Serveis de Recursos
Cientifics i Tècnics (Universitat Rovira i Virgili). Mass spectra (ESI+)
were performed at the Servei d’Espectrometria de Masses (Univer-
sitat de Barcelona). Infrared spectra were obtained with a Niccolet
400FTIR instrument using NaCl discs (for the 3-ferrocenylmethyl-
pentane 2,4-dione) and KBr pellets for the remaining compounds.
Routine 1H and 13C{1H} NMR spectra were recorded with a Gem-
ini-200 MHz or a Mercury-400 MHz instruments, respectively.
31P{1H} NMR of 5 and 6 were recorded with a Varian-Unity-300
instrument using P(OMe3) as reference [d (31P) = 140.17 ppm]. High
resolution 1H NMR spectra and the two-dimensional [{1H–1H}
NOESY, {1H–13C} HSQC and HMBC] were registered with a Varian
VRX-500 or a Bruker Avance DMX-500 MHz instruments at 298 K.
The chemical shifts (d) are given in ppm and the coupling constants
(J) in Hz. The solvent for the NMR experiments was CDCl3 (99.9%)
and SiMe4 was used as reference. Molar conductivity measure-
ments of 10ꢁ3 M solutions of compounds 8 in acetone were deter-
mined at 298 K with a Crison microMC2200 conductivity-meter.
[36]: d = 158.5 (C400), 146.9 (C ), 135.9 (C ), 133.2 (C 00), 126.0
3
0
5
0
1
6
4
0
3
1
2
(C200and C 00), 117.6 (C ), 113.9 (C and C500), 88.4 (C ), 68.4 (C
00
and C5), 68.3 (C5H5), 67.9 (C3 and C4), 23.9 (–CH2–), 11.9 (Meb)
and 10.7 (Mea). For 1b: Anal. Calc. for C22H22N2Fe: C, 71.36; H,
5.99; N, 7.57. Found: C, 71.01; H, 6.05; N, 7.42%. MS (ESI+): 371
[M+H]+. IR: 3067(m), 2909(m), 2839(m), 1596(m), 1504(s),
1430(m), 1384(m), 1105(m), 1020(m), 817(s), 694(s) and 478(m)
cmꢁ1 1H NMR data [36]: d = 7.35–7.41 (m, 4H, H2–H600), 7.30 (td,
.
1H, J = 7.5 and 2.0, H400), 4.13 (s, 5H, C5H5), 4.11 (t, 2H, J = 1.5, H2
and H5), 4.04 (t, 2H, J = 1.5, H3 and H4), 3.47 (s, 2H, –CH2–), 2.23
(s, 3H, Mea) and 2.26 (s, 3H, Meb) and 13C{1H} NMR data [36]:
d = 147.8 (C ), 140.0 (C 00), 136.1 (C ), 128.8 (C and C600), 126.9
3
1
5
0
2
00
0
(C400), 124.8 (C and C500), 121.9 (C ), 88.4 (C ), 68.5 (C5H5), 68.4
(C2 and C5), 67.2 (C3 and C4), 24.3 (–CH2–), 12.2 (Mea) and 11.1
(Meb).
3
00
4
0
1
3.2.3. (l-AcO)2[Pd{j2-C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-
C5H4)Fe(g5-C5H5)]}]2 (2) [R = OMe (2a) or H (2b)]
A 6.8 ꢂ 10ꢁ4 mol amount of 1a (271 mg) or 1b (251 mg) was
3.2. Synthesis of the compounds
dissolved in 10 mL of toluene. Then,
a solution containing
152 mg (6.8 ꢂ 10ꢁ4 mol) of Pd(AcO)2 and 10 mL of toluene was
added. The reaction mixture was protected from the light with alu-
minium foil and refluxed for 3.5 h. During the reflux the deposition
of metallic palladium on the walls of the flask was detected. After
this period the resulting hot solution was filtered though a small
plug (2.0 cm ꢂ 3.5 cm) of Celite. The bright yellow solution was
concentrated to dryness and kept for further use. The Celite was al-
lowed to dry overnight and then washed with CH2Cl2 until nearly
colourless washings were obtained. The washings were poured
into the flask containing the residue and then the resulting solution
was concentrated to ca. 10 mL on a rotary evaporator and passed
through a SiO2 column (5.0 cm ꢂ 3.5 cm). Elution with a CH2Cl2/
MeOH (100:0.4) solution produced the release of a wide and bright
yellow band that was collected and concentrated to dryness on a
rotary evaporator. The solid isolated were collected and dried in
vacuum for 2 days [Yields: 236 mg (62%) and 212 mg (59%) for
2a and 2b, respectively]. Characterization data for 2a: Anal. Calc.
for C50H52N4Fe2O6Pd2: C, 53.17; H, 4.64; N, 4.96. Found: C, 52.91;
H, 4.53; N, 5.06%. MS (ESI+): MS (ESI+): 1082.1 {[M]ꢁAcOꢁ}+ and
517.5 {[M]ꢁ2AcOꢁ}2+/2. IR-data: 3066(m), 2909(m), 1591(s),
1568(s), 1483(m), 1431(m), 1410(s), 1282(m), 1262(m), 1224(m),
3.2.1. 3-Ferrocenylmethyl-pentane 2,4-dione
To a solution of pentane-2,4-dione (0.272 g, 2.72 ꢂ 10ꢁ3 mol)
and ferrocenylmethanol (0.588 g, 2.72 ꢂ 10ꢁ3 mol) in 25 mL of
CH2Cl2, HBF4 [40% in water (10 mL)] was added dropwise. Once
the addition had finished the reaction mixture was stirred at room
temperature for 1 h, diluted with water 40 mL and then extracted
with 15 mL of CH2Cl2. The organic layer was dried over Na2SO4, fil-
tered and concentrated in vacuo. The resulting oil (0.792 g, 98%)
was characterized by mass spectra (ESI+), IR and NMR and used
in the next step without further purification. Characterization data:
MS (ESI+): 299 {[M]+H}+. IR: 3092(m), 3000(m), 2956(m), 2924(m),
1724(s), 1701(s), 1421(m), 1357(m), 1254(m), 1186(m), 1149(m),
1039(m), 1023(m), 1001(m), 821(s), and 618(m) cmꢁ1 1H NMR
.
data [36]: d = 4.12 (s, 5H, C5H5), 4.06 (s, 2H, H2 and H5), 4.03 (s,
2H, H3 and H4), 3.79 (t, 1H, J = 7.2, ˜CH–), 2.89 (d, 2H, J = 7.2, –
CH2–) and 2.12 (s, 6H, Mea and Meb). 13C{1H} NMR data: d = 203
(˜CO), 84.8 (C1), 70.79 (˜CH–), 68.8 (C5H5), 68.5 (C2 and C5), 67.9
(C3 and C4) and 29.8 and 29.0 (Mea and Meb).
3.2.2. [C6H4-4-R-1-{(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5–C5H5)}]
[R = OMe (1a) or H (1b)]
1211(m), 1104(m), 1038(m), 795(s), 684(m) and 482(m) cmꢁ1
.
For R = 4-OMe (1a): 4-methoxyphenylhydrazine (0.469 g,
3.39 ꢂ 10ꢁ3 mol) dissolved in 5 mL of CH2Cl2 was added to 3-ferr-
ocenylmethyl-pentane-2,4-dione (1.02 g, 3.39 ꢂ 10ꢁ3 mol) and the
solvent was evaporated under reduced pressure. The mixture was
then heated for 2 h at 120 °C and cooled. The crude was taken up in
CH2Cl2 and chromatographed on silica gel using diethylether as
eluant. The band released was collected and concentrated to dry-
ness giving a yellowish oily residue [yield: 1.222 g (84%)].
Ligand 1b was synthesized following the same procedure but
using phenylhydrazine (0.287 g, 2.65 ꢂ 10ꢁ3 mol) and the equimo-
1H NMR data [36]: d = 7.10 (dd, 2H, J = 7.5 and 2.0, 2 H600), 6.59
(td, 2H, J = 7.5 and 2.0, 2H500), 6.40 (dd, 2H, J = 7.5 and 2.0, 2H300),
4.12 (s, 10H, 2C5H5), 4.01 (d, 4H, J = 1.5, 2H2 and 2H5), 3.90
(t, 2H, J = 1.5, 2H3 and 2H4), 3.77 (s, 6H, 2 OMe), 3.10 (s, 4H, 2-
CH2–), 2.21 (s, 3H, 2Meb), 2.16 [s, 6H, 2Me(AcO)] and 1.80 (s, 3H,
2Mea). 13C{1H} NMR data [36]: d = 181.0 [˜COO( AcO)], 157.4
(C400), 154.1 (C ), 149.4 (C 00), 138.3 (C 00), 134.4 (C 00), 134.3 (C ),
3
0
2
1
6
5
0
4
0
5
3
1
117.9 (C ), 112.2 (C 00), 109.5 (C 00), 87.3 (C ), 68.9 (C5H5), 68.5
(C5), 68.3 (C2), 67.5 (C3 and C4), 55.5 (OMe), 24.5 (–CH2–), 23.1

2128
A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
[Me(AcO)], 12.1 (Mea) and 11.0 (Meb). For 2b: Anal. Calc. for
tered out. The filtrate was then concentrated to dryness on a rotary
evaporator giving 5a and 5b as yellowish solid, that were collected
and dried in vacuum for 5 h. [Yields: 89 mg (87%) and 82 mg (85%)
and for 5a and 5b, respectively]. Characterization data for 5a: Anal.
Calc. for C43H41N2FeO3Pd: C, 62.45; H, 5.00; N, 3.39. Found: C, 62.0;
H, 5.18; N, 3.18%. MS(ESI+): 767{[M]–AcO}+. IR-data: 3076(m),
3048(m), 2966(m), 2931(m), 1578(s), 1480(s), 1434(s), 1384(s),
1322(m), 1224(m), 1095(m) 721(s), 694(s), 542(s), 534(s),
C
48H48N4Fe2O4Pd2: C, 54.07; H, 4.52; N, 5.24. Found: C, 53.91; H,
4.70; N, 5.19%. 1022.1 {[M]ꢁAcOꢁ}+ and 486.1 {[M]ꢁ2AcOꢁ}2+/2.
IR-data: 3072(m), 2920(m), 2906(m), 1588(s), 1576(s), 1563(s),
1480(m), 1444(s), 1392(s), 1030(m), 815(m), 744(m), 495(m) and
482(m) cmꢁ1 1H NMR data [36]: d = 6.92 (dd, 2H, J = 7.5 and 2,
.
2H600), 6.82 (td, 2H, J = 7.5 and 2.0, H500), 6.63 (td, 2H, J = 7.5 and
2.0, H400), 6.60 (dd, 2H, J = 7.5 and 2.0, 2H300), 4.08 (s, 10H, 2C5H5),
4.05 (d, 4H, J = 1.5, 2H2 and 2H5), 3.90 (t, 4H, J = 1.5, 2H3 and
2H4), 3.07 (–CH2–), 2.26 (s, 3H, 2Meb), 2.14 [s, 6H, 2Me(AcO)]
and 1.77 (s, 3H, 2Mea). 13C{1H} NMR data [36]: d = 182.3
511(m) and 498(m) cmꢁ1 1H NMR data [36]: d = 7.10 (dd, 1H,
.
J = 7.5 and 2.0, H600), 6.60 (dd, 1H, J = 7.5 and 2.0, H300), 6.41 (td,
1H, J = 7.5 and 2.0, H500), 4.13 (s, 5H, C5H5), 4.06 (s, 2H, H2 and
H5), 4.03 (s, 2H, H3 and H4), 3.48 (s, 2H, –CH2–), 2.87 (s, 3H,
OMe), 2.55 (s, 3H, 2Mea), 2.39 (s, 3H, 2Meb) and 1.24 [s, 3H, Me-
(AcO)]. 13C{1H} NMR data [36]: d = 181.4 [˜COO(AcO)], 158.4
3
0
2
1
5
[˜COO(AcO)], 151.8 (C ), 140.8 (C 00), 139.7 (C 00), 136.1 (C ),
0
132.4 (C600), 124.0 (C 00), 122.5 (C 00), 118.8 (C ), 109.2 (C 00), 87.7
(C1), 68.8 (C5H5), 68.4 (C2 and C5), 67.6 (C3 and C4), 24.1 [Me(AcO)],
23.5 (–CH2–), 11.6 (Mea) and 11.2 (Meb).
5
4
4
0
3
3
2
1
(C300), 154.0 (C ), 149.3 (d, JPꢁC = 10.6 C200), 138.2 (C 00), 136.5
0
(C ), 135.1, 131.2, 129.3 and 128.2 (d, aromatic 13C nuclei of the
5
0
3.2.4. (l-Cl)2[Pd{j2-C,N-C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-
C5H4)Fe(g5-C5H5)]}]2 (3) [R = OMe (3a) or H (3b)]
PPh3 ligand), 130.5 (C600), 117.9 (C ), 117.4 (C 00), 111.2 (C 00), 87.7
(C1), 68.9 (C5H5), 68.4 (C2 and C5), 67.5 (C3 and C4), 55.0 (OMe),
23.6 (–CH2–), 23.4 [Me(AcO)], 13.8 (Mea) and 13.2 (Meb). 31P{1H}
NMR data: 44.6. For 5b: Anal. Calc. for C42H39N2FeO2Pd: C, 63.29;
H, 4.93; N, 3.51. Found: C, 63.32; H, 5.10; N, 3.44%. MS (ESI+):
737 {[M]ꢁAcO}+. IR data: 3073(m), 3042(m), 2917(m), 2847(m),
1476(s), 1435(s), 1382(s), 1366(s), 1094(m), 1020(m), 894(m),
4
5
4
0
A 90 mg (7.96 ꢂ 10ꢁ5 mol) amount of 2a or the equimolar
amount of 2b (85 mg) was suspended in 30 mL of acetone, then
LiCl (10 mg, 2.38 ꢂ 10ꢁ4 mol) was added. The resulting suspension
was stirred for 12 h at 298 K. The solid formed was filtered out, air-
dried and then dried in vacuum for 1 day [yields: 69 mg (80%) and
62 mg (76%) for 3a and 3b, respectively]. Characterization data for
3a: Anal. Calc. for C46H46Cl2N4Fe2O2Pd2: C, 51.05; H, 4.28; N,
5.18. Found: C, 49.74; H, 4.35; N, 4.87%. MS (ESI+): m/z = 1047.0
[MꢁCl]+ and 506.0 {[Mꢁ2Clꢁ]2+/2}. IR-data: 3071(m), 2918(m),
1484(s), 1420(s), 1284(m), 1216(m), 1040(s), 728(m), 526(m) and
478(m) cmꢁ1. For 3b: Anal. Calc. for C44H42Cl2N4Fe2Pd2: C, 51.70;
H, 4.14; N, 5.48. Found: C, 51.89; H, 4.20; N, 5.34%. MS (ESI+): m/
z = 987.0 [MꢁCl]+ and 475.0 {[Mꢁ2Clꢁ]2+/2}. IR-data: 3061(m),
2915(m), 1484(s), 1399(s), 1275(m), 815(m), 744(s), 495(m) and
743(s), 691(s), 532(m), 512(m) and 496(m) cmꢁ1 1H NMR data
.
[36]: d = 7.20 (dd, 1H, J = 7.5 and 2, H600), 6.83 (td, 2H, J = 7.5 and
2, H400), 6.52 (dd, 2H, JPꢁH = 6.5 and JHꢁH = 2.0, H300), 6.28 (td, 2H,
J = 7.5 and 2, H400), 4.14 (s, 5H, C5H5), 4.07 (s, 2H, H2 and H5), 4.02
(s, 2H, H3 and H4), 3.42 (s, 2H, –CH2–), 2.52 (s, 3H, 2Mea), 2.33 (s,
3H, 2Meb), and 1.16 [s, 3H, Me(AcO)]. 13C{1H} NMR data [36]:
d = 182.5 [˜COO(AcO)], 153.1 (C ), 140.1 (d, JPꢁC = 10.1 C200),
3
0
2
138.6 (C100), 135.4 (C ), 131.8 (C 00), 135.0, 131.3, 129.2 and 128.4
5
0
6
(d, aromatic 13C nuclei of the PPh3 ligand), 124.6 (C500), 123.7
482(m) cmꢁ1
.
(C400), 120.1 (C ), 113.7 (C 00), 88.0 (C ), 69.2 (C5H5), 68.1 (C and
C5), 67.7 (C3 and C4), 23.9 (–CH2–), 23.0 [Me(AcO)], 13.8 (Meb)
and 13.7 (Mea). 31P{1H} NMR data: 44.3.
4
0
3
1
2
3.2.5. [Pd{j2–C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-C5H4)Fe(g5-
C5H5)]}Cl(py-d5)] (4) [R = OMe (4a) or H (4b)]
These products were prepared in a NMR scale and characterized
in solution by 1H NMR. A 2.0 ꢂ 10ꢁ4 mol amount of the corre-
sponding di-l-chloro-bridged complex 3 (21 mg of 3a or 22 mg
of 3b) was introduced in a NMR tube, then 0.7 mL of CDCl3 were
added. The resulting suspension was then treated with three drops
of deuterated pyridine (py-d5) and shaked for 2 min. This produced
a bright yellow solution that contained the corresponding complex
4a or 4b. 1H NMR data for 4a [36]: d = 7.13 (dd, 1H, H600), 6.58 (dd,
2H, J = 7.5 and 2.0, H500), 5.54 (s, 1H, H300), 4.14 (s, 5H, C5H5), 4.06
(br, 2H, H2 and H5), 4.04 (br, 2H, H3 and H5), 3.58 (s, 3H, OMe),
3.2.7. [Pd{j2–C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2-(g5-C5H4)Fe(g5-
C5H5)]}Cl(PPh3)] (6) [R = OMe (6a) or H (6b)]
These products can be obtained by two different procedures
using either the corresponding complex 3 or the monomeric deriv-
ative 4 [methods (a) and (b), respectively].
Method (a): To a solution containing a 50 mg (4.61 ꢂ 10ꢁ5 mol)
of 3a [or 30 mg (2.93 ꢂ 10ꢁ5 mol) of 3b] and 50 mL
of
CH2Cl2,
triphenylphosphine
for 6a or
[24 mg
15 mg
(9.16 ꢂ 10ꢁ5 mol)
3.49 (s, 2H, –CH2–), 2.77 (s, 3H, 2Mea) and 2.56 (s, 3H, 2Meb).
(5.72 ꢂ 10ꢁ5 mol) for 6b] was added. The resulting
mixture was stirred at 298 K for 1 h and filtered.
The filtrate was concentrated to dryness on a
rotary evaporator and the solid formed was passed
through a short SiO2 column (1.0 cm ꢂ 2.0 cm).
Elution with a mixture of CH2Cl2:MeOH (100:0.2)
produced the release of a yellow band which was
collected and concentrated to dryness on a rotary
evaporator. The solid formed was dried in vacuum
for one day [yields: 52 mg (70%) and 33 mg (72%)
for 6a and 6b, respectively].
3
13C{1H} NMR data for 4a [36]: d = 155.2 (C400), 152.6 (C ), 147.3
0
1
6
5
5
4
(C200), 138.3 (C 00), 136.2 (C 00), 135.9 (C ), 112.6 (C 00), 119.9 (C ),
108.7 (C300), 87.6 (C1), 68.9 (C5H5), 68.4 (C2 and C5), 67.7 (C3 and
C4), 23.7 (–CH2–), 13.7 (Mea) and 12.8 (Meb). 1H NMR data for 4b
[36]: d = 7.21 (dd, J = 7.0 and 1.5, 1H, H600), 7.06 (td, 2H, J = 7.0
and 1.5, H400), 6.71 (td, 2H, J = 7.0 and 1.5, H500), 6.07 (dd, 1H, H300),
4.14 (s, 5H, C5H5), 4.06 (s, 2H, H2 and H5), 4.03 (s, 2H, H3 and
0
0
H4), 3.48 (s, 2H, –CH2–), 2.78 (s, 3H, 2Mea) and 2.60 (s, 3H,
2Meb). 13C{1H} NMR data for 4b [36]: d = 158.4 (C300), 153.5 (C ),
3
0
145.2 (C200), 137.0 (C 00), 133.4 (C ), 130.5 (C 00), 125.2 (C 00), 112.4
1
5
0
6
5
4
0
4
1
2
(C ), 112.2 (C 00), 87.6 (C ), 68.9 (C5H5), 68.4 (C and C5), 67.5 (C3
Method (b): A 50 mg amount (6.2 ꢂ 10ꢁ5 mol of 5a or
6.5 ꢂ 10ꢁ5 mol of 5b) the corresponding complex
[Pd{j2-C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5-
C5H4)Fe(g5-C5H5)]}(AcO)(PPh3)] (5) [R = OMe (5a)
or H (5b)] was dissolved in 10 mL of acetone. Then,
10 mg (9.5 ꢂ 10ꢁ5 mol) of LiCl was added. The
reaction mixture was stirred at 298 K for 2 h and
then filtered out. The resulting yellow filtrate was
concentrated to ca. 2 mL on a rotary evaporator.
and C4), 23.6 (–CH2–), 13.8 (Mea) and 13.1 (Meb).
3.2.6. [Pd{j2–C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2–(g5–
C5H4)Fe(g5–C5H5)]}(AcO)(PPh3)] (5) [R = OMe (5a) or H (5b)]
Compound 2a (70 mg, 6.2 ꢂ 10ꢁ5 mol) or 2b (65 mg, 6.1 ꢂ 10ꢁ5
mol) or was dissolved in 20 mL of CH2Cl2, then PPh3 [33 mg
(12.6 ꢂ 10ꢁ5 mol) for 5a or 32 mg (12.2 ꢂ 10ꢁ5 mol) for 5b] was
added. The reaction mixture was stirred at 298 K for 20 min and fil-

A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
2129
Addition of n-hexane followed by slow evaporation
of the solvents at 4 °C produced the precipitation of
the complexes. The solids were collected by filtra-
tion and then dried in vacuum for one day [yields:
34 mg (70%) and 31 mg (67%) for 6a and 6b,
respectively]. Characterization data for 6a: Anal.
Calc. for C41H38ClN2FeOPPd: C, 61.29; H, 4.77; N,
3.49. Found: C, 61.06; H, 4.68; N, 3.27%. MS
(ESI+): 767 {[M]ꢁCl}+. IR-data: 3060(m), 3048(m),
2958(m), 2917(m), 1576(s), 1474(s), 1429(m),
122(s), 1095(s), 1038(s), 692(s), 530(m), 510(m)
7.06 (dd, J = 7.5 and 2.0, H500), 6.60 (d, J = 2.0, H300), 5.38 [s, 1H,
˜CH(acac)], 4.13 (s, 5H, C5H5), 4.06 (t, 2H, J = 1.5, H2 and H5), 4.03
(t, 2H, J = 1.5, H3 and H4), 3.51 (s, 3H, OMe), 3.48 (s, 2H, -CH2-),
2.55(s, 3H, Mea), 2.52 (s, 3H, Meb), 2.07 (s, 3H, Mec) and 1.99 (s,
3H, Med). 13C{1H} NMR data [36]: d = 188.5 and 188.9 [˜CO(acac)],
3
4
2
1
5
0
0
151.1 (C ), 150.2 (C 00), 145.3 (C 00), 136.4 (C 00), 135.6 (C ), 128.6
4
5
3
(C600), 119.0 (C ), 116.3 (C 00), 111.6 (C 00), 100.2 [˜CH(acac)], 87.7
0
(C ), 69.9 (C5H5), 68.4 (C and C ), 67.7 (C and C4), 55.6 (OMe),
27.8 (Mec and Med), 23.5 (–CH2–), 12.4 (Meb) and 10.6 (Mea). For
7b: Anal. Calc. for C27H28N2O2FePd: C, 56.42; H, 4.91; N, 4.87.
Found: C, 56.31; H, 5.05; N, 4.62%. MS (ESI+): m/z = 574.1 [M+].
IR: 3067(m), 2956(m), 2922(m), 1587(s), 1513(s), 1463(m),
1
0
2
5
0
3
0
and 493(m) cmꢁ1 1H NMR data [36]: d = 7.30–
.
7.68 (m, 15H, aromatic protons of the PPh3 ligand),
7.04 (dd, 1H, J = 7.5 and 2, H600), 6.38 (dd, 1H, J = 7.5
and 2, H500), 6.16 (d, 1H, J = 7.5, H300), 4.12 (s, 5H,
C5H5), 4.09 (s, 2H, H2 and H5), 4.04 (s, 2H, H3 and
H4), 3.45 (s, 2H, –CH2–), 2.94 (s,3H, OMe), 2.69 (s,
1443(m), 1399(m), 1019(m), 1034(m), 503(m) and 485(m) cmꢁ1
.
1H NMR data [36]: 7.57 (td, 1H, 3J = 7.5 and 2.0, H600), 7.06 (td,
J = 7.5, 2.0, H500), 7.13 (dd, J = 7.5, 2.0, H300), 6.97 (td, J = 7.5, 2.0,
H400), 5.36 [s, 1H, ˜CH(acac)], 4.14 (s, 5H, C5H5), 4.02 (t, 2H,
3J = 1.5, H2 and H5), 3.97 (t, 2H, 3J = 1.5, H3 and H4), 3.57 (s, 2H, –
CH2–), 2.57 (s, 3H, Mea), 2.53 (s, 3H, Meb), 2.06 (s, 3H, Mec) and
1.98 (s, 3H, Med). 13C{1H} NMR data [36]: 188.0 and 188.3
3H, 2Mea) and 2.42 (s, 3H, 2Meb). 13C{1H} NMR
3
0
data [36]: d = 154.9 (C300), 153.8 (C ), 147.3 (d,
5
0
3
2
1
5
JPꢁC = 9.6, C200), 136.1 (C ), 135.3 (C100), 135.1,
[˜CO(acac)], 151.1 (C ), 145.3 (C 00), 136.3 (C 00), 135.1 (C ), 131.8
0
0
131.2, 129.0 and 128.2 (d, aromatic 13C nuclei of
(C600), 124.8 (C 00), 123.7 (C 00), 119.5 (C ), 112.9 (C 00), 100.1
5
4
4
3
0
the PPh3 ligand), 125.9 (C600), 120.2 (C500), 114.8
[˜CH(acac)], 87.8 (C ), 69.8 (C5H5), 68.4 (C and C ), 67.7 (C
1
0
2
5
0
3
0
4
4
1
2
(C ), 111.2 (C 00), 88.0 (C ), 68.9 (C5H5), 68.5 (C
and C4), 23.7 (–CH2–), 27.1 (Mec and Med), 10.5 (Mea) and 12.4
0
and C5), 67.6 (C3 and C4), 55.0 (OMe) 23.8 (–CH2–
), 13.4 (Mea) and 13.0 (Meb).31P{1H} NMR data:
d = 45.82. For 6b: Anal. Calc. for C40H36ClN2FePPd:
C, 62.10; H, 4.69; N, 3.62. Found: C, 62.35; H,
4.80; N, 3.73%. MS (ESI+): 737 {[M]ꢁCl}+. IR-data:
3090(w), 3053(w), 2904(w), 1476(s), 1433(s),
1383(m), 1097(s), 1020(m), 997(m), 744(s),
701(s), 688(s), 560(s), 514(s), 496(s) and 483(m)
(Meb).
3.2.9. [Pd{(MeO2C–C@C–CO2Me)2(C6H3-4-R-1-[(3,5-Me2–C3N2)–
CH2–(g5-C5H4)Fe(g5-C5H5)]}Cl] (8) [R = OMe (8a) or H (8b)]
A 8.1 ꢂ 10ꢁ4 mol amount of the corresponding di-l-chloro-
bridged complex (3) [83 mg of 3a or 88 mg of 3b] was suspended
in 30 mL of CH2Cl2. Then MeO2C–C„C–CO2Me [0.4 mL
(32.5 ꢂ 10ꢁ4 mol)] was added dropwise under vigorous stirring at
298 K. Once the addition had finished the reaction mixture was re-
fluxed for one day and then concentrated on a rotary evaporator to
ca. 5 mL. The deep-orange solution was passed through a short
cmꢁ1 1H NMR data [36]: d = 7.30–7.72 (m, 15H,
.
aromatic protons of the PPh3 ligand), 7.14 (dd,
1H, J = 7.5 and 2, H600), 6.85 (td, 1H, J = 7.5 and 2,
H500), 6.57 (d, J = 7.5, H300), 6.29 (td, 2H, J = 7.5 and
2, H400), 4.13 (s, 5H, C5H5), 4.10 (s, 2H, H2 and H5),
4.04 (s, 2H, H3 and H4), 3.51 (s, 2H, –CH2–), 2.73
SiO2 colum (1.0 cm ꢂ 2.0 cm). Elution with
a CH2Cl2:MeOH
(100:0.1) mixture produced the release of a bright orange band
that was collected and concentrated to dryness on a rotary evapo-
rator. The residue was then dried under reduced pressure for one
day [yields: 87 mg (67%) and 91 mg (68%) for 8a and 8b, respec-
tively]. Characterization data for 8a: Anal. Calc. for C35H35N2O9-
FePdCl: C, 59.93; H, 4.27; N, 3.39. Found: C, 60.0; H, 4.30; N,
3.30%. MS (ESI+): m/z = 789.1 {[M]ꢁClꢁ]+. IR data: 3084(m),
2997(m), 2947(m), 1731(broad, s), 1436(s), 1390(m), 1258(s),
1227(s), 1104(m), 1051(m), 1000(s), 819(m), 801(s) 499(m) and
481(m) cmꢁ1. K (10ꢁ3 M in acetone at 298 K) = 12 Xꢁ1 cm2. 1H
NMR data [36]: d = 7.12 (d, 1H, H600), 6.62 (d, 1H, H600), 6.50 (d,
1H, J = 7.5 and 2.0, H300), 4.10 (s, 5H, C5H5), 4.03 (t, 2H, J = 1.5, H2
and H5), 3.98 (t, 2H, J = 1.5, H3 and H4), 3.77 (s, 3H, OMe), 3.71 (s,
3H, OMe), 3.69 (s, 3H, OMe), 3.52 (s, 2H, –CH2–), 3.04 (s, 3H,
OMe). 2.38 (s, 3H, Mea) and 2.24 (s, 3H, Meb). 13C{1H} NMR data
[36]: d = 170.0, 165.9, 163.4 and 162.0 (4 ˜CO2), 158.8 (Cc), 154.6
(s, 3H, 2Mea) and 2.51 (s, 3H, 2Meb). 13C{1H}
3
0
NMR data [36]: d = 155.1 (C300), 152.4 (C ), 146.1
1
5
(C200), 140.3 (C 00), 135.8 (C ), 135.1, 131.2, 129.3
and 128.2 (d, aromatic 13C nuclei of the PPh3
ligand), 130.7 (C600), 124.3 (C500), 123.8 (C400), 114.4
0
(C ), 87.2 (C ), 69.6 (C5H5), 68.6 (C and C5), 67.6
(C3 and C4), 23.9 (–CH2–), 13.5 (Meb), and 13.3
(Mea). 31P{1H} NMR data: d = 45.70.
4
0
1
2
3.2.8. [Pd{j2–C,N–C6H3-4-R-1-[(3,5-Me2–C3N2)–CH2-(g5-C5H4)Fe(g5-
C5H5)]}(acac)] (7) [R = OMe (7a) or H (7b)]
A mixture formed by the corresponding complex 3 [80 mg
(7.4 ꢂ 10ꢁ5 mol) of 3a or 75 mg (7.3 ꢂ 10ꢁ5 mol) of 3b] and
40 mL of acetone was treated carefully with thallium(I) acetylace-
tonate [45 mg (14.8 ꢂ 10ꢁ5 mol) for 7a or 44 mg (14.5 ꢂ 10ꢁ5 mol)
for 7b]. The resulting mixtures were stirred overnight at 298 K. The
precipitate formed (TlCl) was removed by filtration with Whatman
paper and the filtrate was concentrated to dryness on a rotary
evaporator. The residue formed was treated with ca. 5 mL of CH2Cl2
and the undissolved material were removed by filtration with
Whatman paper. Concentration of the filtrate to dryness on a ro-
tary evaporator produced compounds 7 as yellow solids [yields:
60 mg (67%) for 7a and 58 mg (69%) for 7b]. Characterization data
for 7a: Anal. Calc. for C28H30N2O3FePd: C, 55.60; H, 5.00; N, 4.63.
Found: C, 55.32; H, 5.18; N, 4.50%. MS (ESI+): m/z = 604.1 [M+]. IR
data: 3092(m), 3068(m), 2942(m), 2828(m), 1571(s), 1518(s),
1396(s), 1270(s), 1225(s), 1050(m), 1018(m), 782(m), 473(m) and
3
2
5
d
1
(C400), 151.6 (C ), 151.4 (C 00), 140.1 (C ), 139.4 (C ), 139.2 (C 00),
0
0
137.2 (Cb), 127.4 (C600), 122.3 (C ) 116.7 (C 00), 112.9 (C ), 111.7
a
5
4
0
(C300), 86.7 (C ), 69.8 (C5H5), 68.4 (C and C ), 67.5 (C and C4),
58.7, 53.8, 53.2 and 53.0 (4 OMe), 24.5 (–CH2–), 12.6 (Meb) and
11.7 (Mea). For 8b: Anal. Calc. for C34H33N2O8FePdCl: C, 51.34; H,
4.18; N, 3.52. Found: C, 51.27; H, 4.22; N, 3.50%. (ESI+): m/
z = 759.0 {[M]ꢁClꢁ}+. IR: 3088(m), 2991(m), 2950(m), 1724(s),
1432(s), 1376(m), 1260(s), 1226(s), 1103(m), 1021(m), 801(s)
and 481(m) cmꢁ1. K (10ꢁ3 M in acetone at 298 K) = 18 Xꢁ1 cm2.
1
2
0
5
0
3
0
1H NMR data [36]: d = 7.21 (dd, 1H, J = 7.5 and 2.0, H600), 7.02–
7.15 (m, 2H, H4 and H500), 6.53 (d, 1H, J = 7.5 and 2.0, H 00), 4.08
3
00
(s, 5H, C5H5), 4.02 (t, 2H, J = 1.5, H2 and H5), 3.97 (t, 2H, J = 1.5,
H3 and H4), 3.78 (s, 3H, OMe), 3.74 (s, 3H, OMe), 3.72 (s, 3H,
OMe), 3.50 (s, 2H, –CH2–), 3.05 (s, 3H, OMe), 2.40 (s, 3H, Mea)
and 2.26 (s, 3H, Meb). 13C{1H} NMR data [36]: 169.9, 165.8, 163.2
489(m) cmꢁ1 1H NMR data [36]: d = 7.16 (td, J = 7.5 and 2.0, H600),
.

2130
A. González et al. / Journal of Organometallic Chemistry 693 (2008) 2119–2131
3
2
and 161.1 (4 ˜CO2), 157.9 (Cc), 151.9 (C300), 151.4 (C ), 142.5 (C 00),
which 5092 were assumed as observed applying the condition
I > 2r(I). Three reflections were measured every 2 h as orientation
and intensity control, significant intensity decay was not observed.
Lorentz-polarization and absorption corrections were made.
The structure was solved by Direct methods, using SHELXS com-
puter program [37] and refined by full-matrix least-squares meth-
od with SHELX97 computer program [38] using 17813 reflections,
0
5
0
1
d
b
6
139.9 (C ), 139.2 (C 00), 138.2 (C ), 137.0 (C ), 128.5 (C 00), 123.9
(C500), 123.0 (C ’), 119.1 (C ), 112.0 (C 00), 86.8 (C ), 69.8 (C5H5),
4
a
4
1
0
68.5 (C2 and C ), 67.5 (C and C4), 58.8, 52.8, 53.1 and 53.8 (4
5
0
3
0
OMe), 24.6 (–CH2–), 12.6 (Meb) and 12.1 (Mea).
3.3. Electrochemical studies
(very negative intensities were not assumed). The function mini-
P
2
2 2
Electrochemical data were obtained by cyclic voltammetry un-
der nitrogen at 298 K using acetonitrile (HPLC grade) as solvent,
tetrabutylamonium hexafluorophosphate {(Bu4N)[PF6], 0.1 M} as
supporting electrolyte and a potentiostat M263A from EG&G
instruments. The potentials were referred to an Ag–AgNO3 (0.1 M
in acetonitrile) electrode separated from the solution by a medium
porosity fritted disk. A platinum wire auxiliary electrode was used
in conjunction with a platinum disc working Tacussel-Edi rotatory
electrode (3.14 mm2). Cyclic voltammograms of ferrocene were re-
corded before and after each sample to ensure the stability of the
Ag–AgNO3 electrode. Cyclic voltammograms of freshly prepared
solutions (10ꢁ3 M) of the samples in acetonitrile were run and
the average values of the potentials were then referred to ferro-
cene, which was used as internal reference. Under these experi-
mental conditions the standard error of the measured potentials
was 5 mV. In all the experiments, cyclic voltammograms were
registered using scan speeds (t) varying from 10 mV/sꢁ1 to
mized was wkFoj ꢁ jFcj j , where w = [r2(I) + (0.0657P)2]ꢁ1, and
2
2
P = (jFoj + 2jFcj )/3; f, f0 and f00 were taken from the bibliography
[39]. The molecule of CH2Cl2 was disordered and the positions of
its atoms were fixed. The remaining hydrogen atoms were com-
puted and refined, using a riding model, with an isotropic temper-
ature factor equal to 1.2 time the equivalent temperature factor of
the atom which are linked. The final R (on F) factor was 0.043, wR
2
(on jFj ) = 0.141 and goodness of fit = 0.889 for all observed reflec-
tions. Number of refined parameters was 449. Max. shift/
esd = 0.00, Mean shift/esd = 0.00. Max. and min. peaks in final dif-
ference synthesis was 0.783 and ꢁ0.608 e Åꢁ3, respectively. Fur-
ther details concerning the solution and refinement of this
crystal structure are presented in Table 2.
Acknowledgements
Financial support from the Ministry of Science and Technology
(CTQ2006-0207
acknowledged.
100 mV/sꢁ1
.
and
CTQ2006-02390/BQU)
is
gratefully
3.4. Crystallography
Appendix A. Supplementary material
A prismatic crystal of 6b ꢀ CH2Cl2 (sizes in Table 2) was selected
and mounted on a Enraf-Nonius CAD4 four-circle diffractometer.
Unit-cell parameters were determined from automatic centering
of 25 reflections (12° < h < 21°) and refined by least-squares meth-
od. Intensities were collected with graphite monochromatized Mo
Ka radiation, using x/2h scan-technique. The number of reflections
measured in the range 2.14° 6 h 6 29.97° was 12292 reflections of
CCDC 673141 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2008.02.033.
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Table 2
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