1-Methyl-4-ferrocenylmethyl-3,5-diphenylpyrazole: A versatile ligand for palladium(II) and platinum(II)

Article abstract of DOI:10.1016/j.jorganchem.2009.07.006

The syntheses and characterization of two novel ferrocene derivatives containing 3,5-diphenylpyrazole units of general formula [1-R-3,5-Ph₂-(C₃N₂)-CH₂-Fc] {Fc = (η⁵-C₅H₅)Fe(η

Full text of DOI:10.1016/j.jorganchem.2009.07.006

Journal of Organometallic Chemistry 694 (2009) 3633–3642
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
1-Methyl-4-ferrocenylmethyl-3,5-diphenylpyrazole: A versatile ligand
for palladium(II) and platinum(II)
c
c
Pradipta Kumar Basu a, Asensio González a, Concepción López b, , Mercè Font-Bardía , Teresa Calvet
*
a Laboratori de Química Orgànica, Facultat de Farmacia, Universitat de Barcelona, Pl. Pius XII s/n, E-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 Cristalꢀlografia, Mineralogía i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès s/n, E-08028-Barcelona, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
The syntheses and characterization of two novel ferrocene derivatives containing 3,5-diphenylpyrazole
units of general formula [1-R-3,5-Ph2-(C3N2)-CH2-Fc] {Fc = (
5-C5H5)Fe( 5-C5H4) and R = H (2) or Me
Received 3 March 2009
Received in revised form 30 June 2009
Accepted 6 July 2009
g
g
(3)} together with a study of their reactivity with palladium(II) and platinum(II) salts or complexes under
different experimental conditions is described. These studies have allowed us to isolate and characterize
trans-[Pd{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}2Cl2] (4a) and three different types of heterodimetallic com-
plexes: cis-[M{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2(dmso)] {M = Pd (5a) or Pt (5b)}, the cyclometallated
Available online 9 July 2009
Keywords:
Ferrocene derivatives
Cyclometallation
Palladium(II) complexes
Platinum(II) complexes
Activation of sigma(C–H) bonds
products [M{j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-Fc}Cl(L)] with L = PPh3 and M = Pd (6a) or Pt
(6b) or L = dmso and M = Pt (8b) and the trans-isomer of [Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2(dmso)]
(7b). In compounds 4a, 5a, 5b and 7b, the ligand behaves as a neutral N-donor group; while in 6a, 6b
and 8b it acts as a bidentate [C(sp2,phenyl),N(pyrazole)]ꢁ group. A comparative study of the spectroscopic
properties of the compounds, based on NMR, IR and UV–Visible experiments, is also reported.
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
[9] or platinated [10] complexes can also be isolated. The interest
on metallacycles with a r(M–C) (M = Pd or Pt) bond has increased
The synthesis and design of ferrocene derivatives containing
heterocyclic systems have attracted great interest in recent years
[1–3] because of their physical or chemical properties as well as
for their applications in a wide variety of areas including homoge-
neous catalysis [1,2d,3c] and Biomedicine [2e]. In this sort of com-
pounds, the presence of heterocycles with one or more atoms with
good donor abilities is especially interesting in view of their use as
ligands for transition metals to give heteropolymetallic complexes
[1,2d,4] in which the existence of two or more proximal metal ions
may induce a co-operative effect [4].
On the other hand, palladium(II) and platinum(II) complexes
with heterocyclic ligands with two potentially donor atoms is
one of the research areas that has undergone a fast development
during the last years [5–17]. Among all the examples reported so
far those containing pyrazole backbones are specially attractive
[6–8]. Compounds of this kind exhibiting greater antitumoral
activity and lower toxicity than cis-[PtCl2(NH3)2] or antibacterial
activity have been reported [6c,7h]. Furthermore, some examples
of their utility in Macromolecular Chemistry [7a,i–k] or in homoge-
neous catalysis [8a] have also been published.
exponentially due to their properties and applications in different
areas [11–17]. Metallomesogens [11], precursors for homogeneous
catalysis [13], antitumor drugs [14] and ‘‘building blocks” for
Supramolecular Chemistry [15] containing pallada- and platinacy-
cles have been reported. In addition, the high reactivity of the
r(M–C) bond in this sort of compounds makes them valuable pre-
cursors in organic synthesis [11a,12b,c,16] including the total syn-
thesis of natural products [12b,16]. However, and despite the
increasing interest on palladium(II) and platinum(II) complexes
with ligands containing simultaneously a ferrocenyl unit and a
(N,O) or a (N,S) heterocycle [3,4], parallel studies on related com-
pounds with pyrazole rings are scarce [4c,18,19]. A few palla-
dium(II) complexes containing this type of ligands are known
and most of them contain additional allylic ligands [3c,19]. Only
one example of a cyclopalladated complex having simultaneously
the ferrocenyl and the pyrazolyl units has been described so far
[4c], but platinum(II) derivatives are still unknown. In view of
these facts, and as a part of a project centred on the synthesis of
heterodimetallic complexes with heterocycles having ferrocenyl
moieties [3c,d,4,12d], we focused our attention on: (a) the synthe-
sis of novel pyrazolyl containing ferrocene derivatives and (b) the
study of their reactivity towards palladium(II) and platinum(II)
salts or complexes. In this work, we present the syntheses and
In addition, when the pyrazole contains substituents in which
there is a
r(C–H) bond with the proper orientation, cyclopallada-
characterization of [1-R-3,5-Ph2-(C3N2)-CH2-Fc] {Fc = (
g
5-C5H5)Fe
* Corresponding author. Tel.: +34 93 403 91 34; fax: +34 490 77 25.
E-mail address: conchi.lopez@qi.ub.es (C. López).
(g
5-C5H4) and R = H (2) or Me (3)} (Scheme 1) that contain the
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.07.006

3634
P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
Scheme 1. (i) HBF4 (40%)/CH2Cl2. (ii) N2H4, EtOH under reflux. (iii) NaOH (40%), CH2Cl2 and MeI.
3,5-diphenylpyrazolyl group in the pendant arm of the ferrocene as
well as a variety of palladium(II) and platinum(II) complexes de-
rived from these ligands.
trans-isomer (4a). In addition, the IR spectrum of 4a in the range
of metal–ligand vibrations showed two bands at
m = 498 and
334 cmꢁ1. According to Ref. [27] these absorptions are due to the
Pd–N and Pd–Cl stretching vibrations of trans-[Pd(N-donor)2Cl2]
complexes. In view of these findings we assume that 4a is the
trans-isomer of [Pd{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}2Cl2].
2. Results and discussion
In contrast with these results, when the reaction was carried
out using equimolar amounts of 3 and [PdCl2(dmso)2] [24] a differ-
ent product was obtained. Elemental analyses were consistent
with those expected for [Pd{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2
(dmso)] (5a) (Scheme 2, step (ii)) and its 1H NMR spectrum in
CDCl3 at 298 K showed an intense singlet at 3.25 ppm assigned
to the protons of the dmso ligand; however, no evidence of the
existence of NOE peaks between these protons and any of the coor-
dinated ligand 3 were detected in the {1H–1H} NOESY spectrum.
The far IR spectrum of 5a showed two absorption bands of the
Pd–Cl stretching vibrations at 298 and 320 cmꢁ1. Their position
is similar to those reported for [PdCl2(dmso)(L)] with L = 5,7-dit-
ertbutyl-1,2,4-triazolo[1,5-a]pyrimidine, for which: (a) the crystal
structure confirmed a cis-arrangement of the two Clꢁ ligands and
(b) only one singlet due to the protons of the dmso ligand was also
observed in the 1H NMR spectrum [28]. On these bases, we tenta-
tively postulate that in 5a, the Clꢁ ligands are in a cis-disposition.
It is well-known that for N-donor ligands (L), the formation of
the palladacycle usually takes place in two steps, first the coordina-
tion of two (or one) units of the ligand to give trans-[Pd(L)2X2] {or
[Pd(L)X3]ꢁ} species, followed by the subsequent electrophilic
attack of the palladium(II) species formed to the carbon atom
[11a,29]. Despite the arrangement of ligands in 4a is identical to
those of the trans-[Pd(L)2X2] species formed in the first step of
the cyclopalladation process, no evidence of the formation of any
palladacycle were detected by 1H NMR when 4a was refluxed in
toluene for long periods (up to 12 h). In view of these results and
since it is well-known that Pd(OAc)2 is a better metallating agent
than [PdCl2(dmso)2] [11a,29] we also studied the reactivity of 3
with this salt.
2.1. The ligands
The preparation of the new ferrocenyl ligands [1-R-3,5-Ph2-
(C3N2)-CH2-Fc] (R = H or Me) was achieved following the sequence
of reactions presented in Scheme 1. First, 3-ferrocenylmethyl dib-
enzoylmethane (1) was obtained by electrophilic coupling on posi-
tion 3 of the diketone using ferrocenylmethanol (Fc-CH2OH) [20] in
a two-phase CH2Cl2/40% aqueous HBF4 mixture (Scheme 1, step (i))
[21]. Subsequent treatment with hydrazine in ethanol at reflux
temperature (Scheme 1, step (ii)) [4c] followed by purification of
the crude product of the reaction by column chromatography
gave [1-R-3,5-Ph2-(C3N2)-CH2-Fc] with R = H (2). The subsequent
alkylation with methyl iodide (Scheme 1, step (iii)) using the same
procedure as described before for indigo [22], gave [1-Me-3,5-Ph2-
(C3N2)-CH2-Fc] (3) in good yield (98%).
Compounds 1–3 were characterized by elemental analyses,
mass spectrometry, infrared spectra and mono- and two-dimen-
sional NMR experiments. The elemental analyses (Section 3) were
consistent with the proposed formulae and their mass spectra
showed a peak at m/z = 422.1 (for 1), 419.1 (for 2) and 433.1 (for
3) that agree with the values expected for the {[M]+H}+ cations.
Proton NMR spectra of 1–3 showed the typical patterns of mon-
osubstituted ferrocene derivatives [1,23] and the resonances due to
the –CH2– protons appeared as a doublet (in 1) or as a singlet (in 2
and 3) in the range 3.10–4.00 ppm. The signals observed in the
13C{1H} NMR spectra of 1–3 were assigned with the aid of two-
dimensional {1H–13C} HSQC and HMBC experiments. The reso-
nances due to the quaternary carbon nuclei of 1–3 were easily
identified by comparison of the signals detected in the 13C{1H}
and in the {1H–13C} HSQC, and the analyses of the cross peaks be-
tween the –CH2– protons allowed to assign the resonances of the
ipso carbon of the ferrocenyl unit (C1Fc) and of the C3–C5 nuclei.
When ligand 3 was treated with Pd(OAc)2 in toluene under re-
flux for 3.5 h followed by: (a) the addition of PPh3 first and LiCl la-
ter on and (b) a column chromatography on silica gel, the
cyclopalladated complex [Pd{j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-
2.2. Palladium(II) complexes
CH2-Fc}Cl(PPh3)] (6a) (Scheme 2, step (iii)) was isolated in fairly
good yield (74%). In this product, the ligand acts as a bidentate
[C(sp2,phenyl),N(pyrazole)]ꢁ group and the phosphine is in a cis-
arrangement in relation to the metallated carbon atom, in good
agreement with the so-called transphobia effect [30].
It should be noted that when any of the reactions depicted in
Scheme 1, steps (i) and (ii) were performed under identical condi-
tions but using [1-R-(3,5-Ph2-(C3N2)-CH2-Fc] with R = H (2), in-
stead of ligand 3, the starting materials were recovered
unchanged and no evidence of the formation of any palladium(II)
complex was detected by NMR. The well-known tautomeric pro-
cess involving the proton transfer between the two nitrogen atoms
Treatment of [1-Me-3,5-Ph2-(C3N2)-CH2-Fc] (3) with [PdCl2
(dmso)2] [24] (in a 2:1 molar ratio) in refluxing methanol for
3.5 h under reflux produced a pale yellow solid that was identified
as the heterotrimetallic complex [Pd{1-Me-3,5-Ph2-(C3N2)-CH2-
Fc]}2Cl2] (4a) (Scheme 2, step (i)). It is well-known that in
palladium(II) complexes of the type [Pd(L)2Cl2] (with L = planar
N-donor ligand) the ‘‘PdCl2” is nearly orthogonal to the main plane
of the N-donor ligand [25,26]. For this arrangement of groups, the
use of molecular models reveals that in cis-[Pd{1-Me-3,5-Ph2-
(C3N2)-CH2-Fc]}2Cl2], the steric hindrance is greater than in the

P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
3635
Scheme 2. (i) Cis-[PdCl2(dmso)2] (molar ratio 3:Pd = 2)/MeOH under reflux. (ii) Cis-[PdCl2(dmso)2] (molar ratio 3:Pd = 1)/MeOH under reflux. (iii) Pd(OAc)2/toluene under
reflux; PPh3/CH2Cl2; LiCl, acetone and SiO2 column chromatography.
of the pyrazolyl moiety may hinder the coordination of ligand 2 to
palladium(II) [31].
3.31 ppm (3JPt–H = 20.3 Hz)]. This suggested that the two Me groups
of the dmso were not equivalent. A column chromatography on sil-
ica gel allowed to isolate 7b and a bright orange microcrystalline
product (5b). Elemental analyses of 5b also agreed with those ex-
pected for [Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2(dmso)], thus sug-
gesting that 7b and 5b might be two isomers of this compound.
The signal detected in the 195Pt{1H} NMR of 5b (at d = ꢁ2925 ppm)
also is consistent with the values of platinum(II) complexes with a
‘‘N,Cl2,S(dmso)” set of donor atoms but it was downfield shifted in
2.3. Platinum(II) complexes
The reaction of equimolar amounts of [1-Me-3,5-Ph2-(C3N2)-
CH2-Fc] (3) and cis-[PtCl2(dmso)2] [32] in refluxing methanol for
3.5 h followed by column chromatography on silica gel produced
a yellow solid, whose characterization data (see below and Section
3) agreed with those expected for [Pt{1-Me-3,5-Ph2-(C3N2)-CH2-
Fc]}Cl2(dmso)] (7b) (Scheme 3, step (i)).
When the reaction was carried out under identical experimen-
tal conditions but using dry toluene as solvent (Scheme 3, step (ii))
the 1H NMR spectrum of the raw material showed two superim-
posed sets of signals of relative intensities 3.7:1.0 thus indicating
the presence of at least two products. The resonances due to the
major component were identical to those observed for 7b; while
for the minor one (hereinafter referred to as 5b), two singlets of
identical intensity were observed at d = 2.47 (3JPt–H = 20.6 Hz) and
relation to that of 7b (d = ꢁ3015 ppm) and the difference
Dd = d
(for 5b) – d (for 7b) = 90 ppm, falls in the range reported for the
cis- and trans-isomers of [Pt(N-donor ligand)Cl2(dmso)]
{55 ppm < (dcis-ꢁdtrans- < 128 ppm} [34,35a–c,36]. The analysis of
the cross peaks detected in the {1H–1H} NOESY spectrum of 5b
indicated that one of the methyl groups of the dmso ligand (at
d = 2.47 ppm) was close to the ortho protons of the phenyl ring,
which causes the high field shift of this signal, when compared
with that observed for 7b {d = 3.44 ppm (3JPt–H = 20.4 Hz)}, due to
the magnetic anisotropy of the phenyl ring. Furthermore, the far

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P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
Scheme 3. (i) Cis-[PtCl2(dmso)2]/MeOH under reflux. (ii) Cis-[PtCl2(dmso)2]/toluene under reflux. (iii) NaOAc/in MeOH under reflux. (iv) Cis-[PtCl2(dmso)2]/NaOAc/
toluene:MeOH under reflux; SiO2 column chromatography. (v) PPh3/CH2Cl2. (vi) Cis-[PtCl2(dmso)2]/NaOAc/toluene:MeOH/reflux; PPh3/CH2Cl2; SiO2 column chromatography.
IR-spectra of 5b showed two bands due to the stretching of the Pt–
Cl bond (at 348 and 312 cmꢁ1) while that of 7b exhibited only one
(at 355 cmꢁ1). According to Refs. [27,36], all these findings sug-
gested that compounds 5b and 7b differed in the relative arrange-
ment of the Clꢁ ligands {cis-(in 5b) and trans-(in 7b)}.
expected
for
[Pt{j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-
Fc}Cl(dmso)], (8b) (see below and Section 3) in which the ferrocene
derivative 3 behaves as a bidentate {C(sp2,phenyl),N(pyrazole)}ꢁ li-
gand and the dmso group is in a cis-arrangement to the metallated
carbon atom.
In order to confirm the relative arrangement of the Clꢁ ligands
in 5b or 7b, several crystallization procedures were used; however,
most of the experiments failed and only when CH2Cl2 solutions of
5b were evaporated at ꢁ4 °C small crystals were obtained. Unfor-
tunately, they rapidly degraded upon the X-ray radiation at 298 K.
At 243 K unit-cell parameters could be determined (see Section 3)
but even in these conditions, and due to the low stability and poor
quality of the crystal, the number of reflections collected was (951,
Rint = 0.1821) too low as to allow the resolution of the structure.1
On the other hand, the comparison of the results obtained in the
two solvents indicate that the replacement of methanol by toluene
as solvent promotes the preferential formation of the cis-isomer of
[Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2(dmso)]. This result is in good
agreement with those obtained in the reaction of cis-
[PtCl2(dmso)2] with the imine 4Cl–C6H4–CH@N–(CH2)-(40Cl–
C6H4) and related N-donor ferrocenyl ligands [34,37].
Due to the recent interest in platinacycles with heterocyclic li-
gands [10], we attempted the synthesis of cycloplatinated com-
plexes. Since it is well-known that some platinum(II) complexes
of the type [Pt(N-donor ligand)Cl2(dmso)] undergo the intramolec-
ular cycloplatination reaction in the presence of a base, such as
NaOAc [26,33–35,37], we also explored the reactivity of trans-
[Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2(dmso)] (7b) with this salt.
The reaction between equimolar amounts of 7b and NaOAc in
refluxing methanol for 24 h yielded after work up a mixture of
two compounds (Scheme 3, step (iii)). The major component was
identified as 5b. This result is similar to that obtained by Crespo
et al. [37] for the imine 4Cl–C6H4–CH@N–(CH2)-(40Cl–C6H4) and
is consistent with previous studies on the reactivity of related N-
donor ligands with cis-[PtCl2(dmso)2] [35]. Characterization data
of the minor component (see Section 3) were consistent with those
This process (Scheme 3, step (iii)) produced the platinacycle 8b
but the reaction was complex due to the formation of 5b and the
molar ratio 5b:8b was 8.5:1.0. In view of these results and in order
to increase the yield of 8b a different strategy, based on the direct
method reported for the synthesis of a few platinacycles with
bidentate [C(sp2,phenyl or ferrocene), N]ꢁ ligands, was used
[4b,34,35]. Treatment of equimolar amounts of 3, cis-
[PtCl2(dmso)2] and NaOAc in a mixture toluene/methanol under
reflux for 54 h, followed by column chromatography on silica gel,
furnished compounds 8b and 5b (Scheme 3, step (iv)). It should
be noted that the molar ratio 5b:8b decreased as the refluxing time
increased (from 8.5:1.0 for 24 h to 3.7:1.0 for 54 h).
The results obtained in the study of the reactivity of 3 with cis-
[PtCl2(dmso)2] suggest that the formation of the platinacycle 8b is
a multistep process (Scheme 4) in which the main reactions in-
volve, the replacement of one of the dmso ligands of the starting
material by methanol (Scheme 4, A) to give cis-[PtCl2(MeOH)(dm-
so)] which may isomerize to the trans-form (Scheme 4, B). Further
coordination of the N-donor ligand 3, would produce the cis- and
trans-isomers of [Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc]}Cl2(dmso)]
(Scheme 4, steps C and D, respectively) and this may proceed at dif-
ferent rates. Finally, the activation of the r(C–H) bond of the phe-
nyl ring of compound 7b, would produce the platinacycle 8b
(Scheme 4, step E).
It should be noted that the set of reactions presented in Scheme
4 agree with: (a) the mechanism postulated for the cycloplatina-
tion of aryloximes, [38a] (b) the results obtained recently from a
DFT-based theoretical studies of the cycloplatination process
[38b] and previous studies on the cyclometallation of N-donor li-
gands (L) for which it has been demonstrated that trans-
[PtCl2(L)dmso] complexes are the key intermediates of the process
[35a,37].
Further reaction of 8b with the equimolar amount of PPh3 pro-
duced the replacement of the dmso ligand by the phosphine to give
1
A minimum of 2421 reflections were required to achieve a resolution of 1 Å.

P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
3637
Scheme 4.
[Pt{
j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-Fc}Cl(PPh3)],
(6b)
different mode of binding of ligand 3 {N(pyrazole) (in 5b and 7b
or [C(sp2,phenyl),N(pyrazole)]ꢁ (in 6b and 8b)} or (b) the relative
arrangement of the ligands in 5b and 7b. The chemical shift of
the signals follows the trend: 5a < 7b < 6b < 8b. According to the
literature [33,36,41], an up-field shift in 195Pt NMR is related to a
strong interaction between the platinum and its ligands, and since
6b and 8b differ only in the nature of the neutral ligand [PPh3 (in
6b) or dmso (in 8b)], the variations observed in the 195Pt chemical
shift of 6b and 8b can be ascribed to the different donor abilities of
the PPh3 and dmso ligands.
(Scheme 3, step (v)). Characterization data of 6b suggests that this
product is formally identical to the palladacycle 6a, except for the
nature of the metal atom {M = Pd (in 6a) or Pt (in 6b)}. It should be
noted that complex 6b could also be isolated by direct treatment of
3, cis-[PtCl2(dmso)2] and NaOAc under reflux in a toluene:metha-
nol (5:1) mixture, followed by the reaction of the residue obtained
after concentration with an excess (50%) of triphenylphosphine
(Scheme 3, step (vi)).
2.4. Characterization of the palladium(II) and platinum(II) complexes
Due to the ongoing interest of the photophysical properties of
multifunctional heterocyclic ligands and their palladium(II) and
platinum(II) complexes [8,11,42,43] we also studied the Ultravio-
let–Visible spectra of CH2Cl2 solutions of all new products (see
Section 3). The spectra of ligands 2 and 3 showed an intense
The new complexes were characterized by elemental analyses,
mass and infrared spectroscopy and mono-and two-dimensional
NMR spectroscopy. In all cases elemental analyses and mass
spectra (Section 3) were consistent with the proposed formulae.
IR-spectra of the complexes showed the typical bands due to the
S-bonded dmso ligand (5a, 5b, 7b and 8b) [27] or those due to
the PPh3 (in 6a and 6b) [39].
[20 000 <
260 nm. According to the Ref. [8] this absorption is due to a
p* transition of the 3,5-pyrazolyl unit (intraligand transition:
e
< 27 000 Mꢁ1 cm2] band in the range 230 nm < k <
p
?
IT). The palladium(II) and platinum(II) complexes also exhibited a
band in this region and its position did not change appreciably
from those of the free ligand, thus suggesting that it corresponds
to a metal perturbed intraligand transition (MPILT).
The assignment of the signals detected in the 1H and 13C{1H}
NMR spectra (Section 3) of the Pd(II) and Pt(II) complexes was
achieved with the aid of two-dimensional NMR [{1H–1H} NOESY,
COSY and {1H–13C} HSQC and HMBC] experiments. Proton and
13C{1H} NMR spectra of all the compounds exhibited: (a) the typi-
cal pattern of monosubstituted ferrocene derivatives [1,23] and (b)
the resonances due to the dmso (in 4a, 5a, 5b, 7b and 8b) or the
PPh3 (in 6a and 6b) ligands.
In the UV–Vis spectra of ligands 2 and 3 an additional absorp-
tion at 449 nm
(e (e =
= 256 Mꢁ1 cm2, for 2) or 438 nm
269 Mꢁ1 cm2 for 3), due to an electronic d–d transition of the ferr-
ocenyl unit, was also observed. It has been reported that for ferro-
cene derivatives, the presence of electron withdrawing
substituents produce a decrease of the energy of this transition,
while for electron donating groups the effect is opposite [44]. On
this basis, the comparison of the position of band for ligands 2, 3
For the cyclometallated complexes 6a, 6b and 8b the resonance
of the proton in the adjacent position to the metallated carbon
0
(H5 ), was up-field shifted in comparison with its position for the
free ligand and compounds 5a, 5b and 7b, where this ligand be-
haves as a monodentate N-donor group. This trend, that has also
been observed for related [M(C,N)X(L)] complexes with M = Pd(II)
or Pt(II), L = pyridine or phosphines and X = AcOꢁ, Clꢁ, Brꢁ or Iꢁ,
has been attributed to anisotropy of the aromatic rings of the li-
gands L that are close to that proton [15c,33,34,40].
and for the Fc-CH2-NMe2 {k = 402 nm (e
= 302 Mꢁ1 cm2)} [44,45]
suggests that the electron donor ability of the CH2R substituents
increases according to the sequence: 2 < 3 < Fc-CH2-NMe2.
The UV–Vis spectra of compounds 5a, 5b, 6a and 7b also
showed a band in the range 420 nm < k < 440 nm (with extinction
coefficients in the range 165 < e
< 200 Mꢁ1 cm2) and its position
The 195Pt{1H} NMR spectra not only provided convincing evi-
dence for the coordination sphere and structure of the platinum(II)
derivatives but also explained the variations produced by: (a) the
does not vary significantly when ligand 3 binds to the palladium(II)
and platinum(II), thus suggesting that this absorption can be
ascribed to a metal perturbed intraligand transition (MPILT).

3638
P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
Similarly to what happened for the free ligands, for the palla-
dium(II) and platinum(II) complexes presented here this band ap-
pears at lower energies than for their analogues containing the Fc-
CH2-NMe2 as ligand [45].
the solvent for the NMR experiments was CDCl3 (99.9%) and the
references were SiMe4 [for 1H and 13C{1H} NMR], P(OMe)3
[d(31P) = 140.17 ppm] for 31P NMR and H2[PtCl6] [d195Pt{H2-
[PtCl6]} = 0.0 ppm] for 195Pt{1H} NMR experiments. UV–Vis spectra
of 1.6 ꢂ 10ꢁ4 M solutions of the compounds in CH2Cl2 were re-
corded with a Cary 100 scan Varian UV spectrometer. Unit cell
parameters of 5b2 were determined at 243 K with a MAR345 with
an image plate detector diffractometer using 1203 reflections
(3° < h < 31°) and refined by least-squares method.
Finally, it should be noted that for compounds 3, 5b, 6b and 8b,
an additional and poorly defined absorption at 271 nm (for 3) or in
the range 310–320 nm (e
= 1759, 6219, 2338 Mꢁ1 cm2 for 5b, 6b
and 8b, respectively) was also observed in their UV–Vis spectra.
2.5. Conclusions
3.2. Preparation of the compounds
The results presented here have allowed us: (a) to prepare
and characterize the two novel ferrocene derivatives [1-R-3,5-
3.2.1. Preparation of [Fc-CH2-CH{C(O)Ph}2] (1)
Ph2-(C3N2)-CH2-Fc] {Fc = (
g
5-C5H5)Fe(
g
5-C5H4) and R = H (2) or
Dibenzoyl methane (0.68 g, 3.03 ꢂ 10ꢁ3 mol) and Fc-CH2OH
(0.66 g, 3.03 ꢂ 10ꢁ3 mol) were dissolved in 60 mL of CH2Cl2. Then
a solution formed by 12 mL of HBF4 and 8 mL of H2O was added
dropwise under stirring. The resulting mixture was magnetically
stirred at room temperature for 1 h and afterwards it was treated
with 150 mL of H2O. The mixture was extracted with two
(50 mL) portions of CH2Cl2, the organic layer was then dried over
Na2SO4 and the filtrate was concentrated to dryness on a rotary
evaporator. The solid formed was collected and air-dried for one
day. Yield: 1.57 g (84%). Characterization data: Anal. Calc. for
C26H22O2Fe: C, 73.96; H, 5.22. Found: C, 73.81; H, 5.36%. MS
(ESI+): m/z = 422.1 [M+H]+. Rf(CH2Cl2) = 0.62. IR: 1763(w),
1700(s), 1666(s), 1470(s), 1446(w), 1402(w), 1335(s), 1300(s),
1142(s), 1020(s), 990(s), 924(m), 866(m), 821(s), 773(s), 705(s),
645(m), 588(s) and 497(s) cmꢁ1. UV–Vis (c = 1.6 ꢂ 10ꢁ4 M in
Me (3)} that contain a 3,5-diphenyl pyrazole unit and (b) to eval-
uate the coordinating abilities of these ligands with Pd(II) and
Pt(II). The results obtained have shown that compound 3 is more
prone to bind to these ions than the non-methylated derivative
2. The study of the reactivity of
3
with Pd(OAc)2 or
[MCl2(dmso)2] (M = Pd or Pt) under different experimental condi-
tions has allowed us to establish the best experimental condi-
tions to control selectively the preferential formation of the
different sorts of the complexes: trans-[Pd{1-Me-3,5-Ph2-(C3N2)-
CH2-Fc}2Cl2] (4a) or the heterodimetallic products cis-[M{1-Me-
3,5-Ph2-(C3N2)-CH2-Fc}Cl2(dmso)] {M = Pd (5a) or Pt (5b)}, the
trans-isomer of the platinum(II) complex (7b) and the cyclomet-
allated compounds: [M{j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-
Fc}Cl(L)] {with L = PPh3 and M = Pd (6a) or Pt (6b) or L = dmso
and M = Pt (8b)} and to tune the mode of binding of 3 in the
complexes {(N) in 4a, 5a, 5b and 7b or [C(sp2,phenyl),N(pyra-
zole)]ꢁ in 6a, 6b and 8b}.
Since platinum(II) compounds containing pyrazole ligands have
greater antitumoral activity and lower toxicity than cis-
[PtCl2(NH3)2] [6c,7h] and some platinum(II) complexes derived
from N-donor ferrocenyl ligands also exhibit antitumoral activity
[46], the new platinum(II) derivatives presented in this work con-
taining simultaneously a ferrocenyl- and a pyrazolyl units appear
to be specially attractive for further studies as antitumoral drugs.
CH2Cl2): k in nm (e
in Mꢁ1 cm2) = 246(23 150) and 340(1944). 1H
NMR data [48]: d = 3.17(dd, 2H, J = 6.5 and 1.0, –CH2–), 4.00(s,
2H, H3Fc and H4Fc), 4.09(s, 2H, H2Fc and H5Fc), 4.12(s, 5H, Cp),
0
0
0
5.29(t, 1H, J = 6.5, H4), 7.51(m, 2H, H4 ), 7.38(m, 4H, H3 and H5 )
0
0
and 7.86(d, 4H, J = 7.0, H2 and H6 ).13C{1H} NMR data [48]:
d = 30.1(–CH2–), 59.8(C4), 67.7(Cp), 67.8(C3Fc and C4Fc), 69.0(C2Fc
0
0
0
0
and C3Fc), 86.1(C1Fc), 126.4(C4 ), 128.7(C3 and C5 ), 136.1(C1 ),
0
0
139.4(C2 and C6 ), and 195.4(>CO).
3.2.2. Preparation of [1-R-3,5-Ph2-(C3N2)-CH2-Fc] with R = H (2)
A solution formed by 1.27 g (3.01 ꢂ 10ꢁ3 mol) of compound 1
and 35 mL of ethanol was treated with 1.5 mL (30.1 ꢂ 10ꢁ3 mol)
of N2H4ꢀH2O. The resulting solution was refluxed for 3 h and then
allowed to cool to room temperature. The subsequent concentra-
tion of the solution on a rotary evaporator produced a yellow res-
idue. The solid was dissolved in CH2Cl2 (ꢃ15 mL) and passed
through a short SiO2 column (5.0 ꢂ 1.0 cm). Elution with CH2Cl2 re-
leased a yellow band that was collected and concentrated to dry-
ness on a rotary evaporator. The solid formed was collected and
dried in vacuum for 2 days. Yield: 0.975 g (98%). Characterization
data: Anal. Calc. for C26H22N2Fe: C, 74.67; H, 5.27; N, 6.70. Found:
C, 74.6; H, 5.4; N, 6.7%. MS (ESI+): m/z = 419.1 [M+H]+.
Rf(CH2Cl2) = 0.22. IR: 1724(m), 1641(w), 1493(s), 1445(s),
1409(w), 1293(s), 1162(m), 1104(s), 1072(s), 1021(s), 999(s),
3. Experimental
3.1. Materials and methods
Compounds [MCl2(dmso)2] (M = Pd or Pt) were prepared as re-
ported previously [24,32], FcCH2OH was synthesized from the fer-
rocenecarboxaldehyde [20] and the remaining reagents were
obtained from commercial sources and used as received. Except
methanol (which was HPLC-grade), the remaining solvents were
dried and distilled before use [47]. Elemental analyses were carried
out at the Serveis de Cientifico-Tècnics (Universitat de Barcelona).
Mass spectra (ESI+) were performed at the Servei d’Espectrometria
de Masses (Universitat de Barcelona). Infrared spectra in the range
4000–400 cmꢁ1 were obtained with a Nicolet 400FTIR instrument
using KBr pellets; while far IR-spectra of 4a, 5a, 5b and 7b (in
the range 200–400 cmꢁ1) were registered with a Bomen-DA3
instrument using polyethylene discs. Routine 1H and 13C{1H}
NMR spectra were recorded with a Mercury-400 MHz instrument.
High resolution 1H NMR spectra and the two-dimensional
[{1H–1H}-NOESY and COSY and {1H–13C}-HSQC and HMBC] exper-
iments were registered with a Varian VRX-500 or a Bruker Avance
DMX-500 MHz instruments at 298 K. The chemical shifts (d) are gi-
ven in ppm and the coupling constants (J) in Hz. 195Pt{1H} NMR
spectra of compounds 5b–8b were obtained with a Bruker-
250 MHz instrument at 298 K. 31P{1H} NMR spectra of 6a and 6b
were recorded with a Varian-Unity-300 instrument. In all cases
920(m), 833(m), 767(s), 698(s), 568(m), 501(s) and 482(m) cmꢁ1
.
UV–Vis (c = 1.6 ꢂ 10ꢁ4 M in CH2Cl2):
k
in nm
(e
in
M
ꢁ1 cm2) = 248(21 919) and 449(256). 1H NMR data [48]:
d = 3.76(s, 2H, –CH2–), 3.62(s, 2H, H3Fc and H4Fc), 3.68(s, 2H, H2Fc
and H5Fc), 3.87(s, 5H, Cp), 6.50(d, 1H, J = 6.5, NH), 7.35(br.m, 2H,
0
0
0
0
H4 ), 7.40-7.53(br.m, 4H, H3 and H5 ) and 7.57(d, 4H, J = 7.5, H2
0
and H6 ). 13C{1H} NMR data [48]: d = 23.8(–CH2–), 66.8(C2Fc, C3Fc
,
0
C4Fc and C5Fc), 68.6(Cp), 88.9(C1Fc), 115.3(C4), 125.4(C4 ),
0
0
0
0
0
128.1(C3 and C5 ), 128.6(C2 and C6 ), 132.2(C1 ) and 145.2(br., C3
and C5).
2
Cystal system: triclinic, a = 12.210(7) Å, b = 15.806(8) Å, c = 17.562(5) Å,
a
= 109.44(3)°, b = 102.79(2)° and c = 91.07(3)°.

P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
3639
3.2.3. Preparation of [1-Me-3,5-Ph2-(C3N2)-CH2-Fc] (3)
mum amount of CH2Cl2 (ꢃ15 mL) and passed through a SiO2 col-
umn (8.5 cm ꢂ 3.0 cm). Elution with CH2Cl2:MeOH (100:1)
released a reddish yellow band that was collected and concen-
trated to dryness on a rotary evaporator. The solid formed (5a)
was collected and dried in vacuum for 2 days. Yield: 300 mg
(56%). Characterization data: Anal. Calc. for C29H30Cl2N2OPdFeS: C,
50.64; H, 4.37; N, 4.07; S, 4.66. Found: C, 50.48; H, 4.52; N, 3.98;
S, 4.60%. MS (ESI+): m/z = 710.1 {[M]+Na}+. Rf(CH2Cl2) = 0.10. IR:
1636(s), 1501(w), 1444(m), 1373(m), 1297(w), 1105(m),
1076(w), 1022(m), 920(w), 822(w), 755(m), 700(s), 496(Pd-N)
and 320 and 298 (Pd–Cl) cmꢁ1. UV–Vis (c = 1.6 ꢂ 10ꢁ4 M in
To a solution containing 800 mg (1.91 ꢂ 10ꢁ3 mol) of com-
pound 2 and 30 mL of toluene, benzyltriethylammonium chloride
(218 mg, 0.95 ꢂ 10ꢁ3 mol) and 7 mL of an aqueous NaOH (40%)
solution were added. Afterwards, 0.24 mL (3.82 ꢂ 10ꢁ3 mol) of
CH3I were added dropwise in two portions and the resulting mix-
ture was magnetically stirred at 298 K for 24 h. After this period
H2O (50 mL) was added and then the mixture was extracted with
two (25 mL) portions of CH2Cl2. The organic layers were combined
and dried over Na2SO4. The resulting filtrate was concentrated to
dryness on a rotary evaporator. The residue was then dissolved
in the minimum amount of CH2Cl2 (ꢃ10 mL) and passed through
a short neutral alumina column (5.0 ꢂ 2.0 cm). Elution with CH2Cl2
released a yellow band that was collected and concentrated to dry-
ness on a rotary evaporator. The solid formed was then dried in
vacuum for 2 days. Yield: 0.811 g (98%). Characterization data: Anal.
Calc. for C27H24N2Fe: C, 75.03; H, 5.56; N, 6.48. Found: C, 75.2; H,
5.5; N, 6.6%. MS(ESI+): m/z = 433.1[M+H]+. Rf(CH2Cl2) = 0.33. IR:
1957(w), 1724(s), 1637(m), 1459(s), 1429(s), 1408(m), 1291(m),
1159(w), 1104(s), 1049(m), 1028(m), 1000(m), 922(w), 828(m),
CH2Cl2): k in nm (e
in Mꢁ1 cm2) = 239(26 818) and 421(193). 1H
NMR data [48]: d = 3.25(s, 12H, dmso), 3.41(s, 2H, –CH2–),
3.54(br., 2H, H3Fc and H4Fc), 3.83(br.s, 8H, –NMe and Cp),
0
00
3.88(br.s, 2H, H2Fc and H5Fc), 7.10–7.20(br. m, 2H, H4 and H4
)
0
0
0
0
00
00
00
00
and 7.30–7.58(br. m. 8H, H2 , H3 , H5 , H6 , H2 , H3 , H5 and H6 ).
13C{1H} NMR data [48]: d = 23.5(–CH2–), 38.6(NMe), 37.4(dmso),
66.9(C3Fc), 67.1(C4Fc), 68.2(C2Fc), 68.3(C5Fc), 68.6(Cp), 87.2(C1Fc),
00
00
0
0
00
0
119.6(C4), 128.5(C5 ), 128.6(C4 ), 128.7(C3 , C5 and C3 ), 128.9(C4 ),
0
00
0
0
00
00
129.4(C1 ), 129.6(C6 ), 129.9(C2 and C6 ), 129.9(C2 ), 131.8(C1 ),
144.6(C5), and 150.9(C3).
817(s), 754(s), 700(m), 680(m), 611(w), 494(s) and 478(m) cmꢁ1
.
in
UV–Vis (c = 1.6 ꢂ 10ꢁ4 M in CH2Cl2):
k
in nm
(
e
M
ꢁ1 cm2) = 242(26 125), 271sh(ꢃ23 019) and 438(269). 1H NMR
3.2.6. Preparation of [Pd{j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-
Fc}Cl(PPh3)] (6a)
data [48]: d = 3.62(s, 2H, –CH2–), 3.76(s, 5H, Cp), 3.88(s, 3H,
NMe), 3.98(br.s, 4H, H2Fc, H3Fc, H4Fc and H5Fc), 7.30–7.50(br.m,
Pd(OAc)2 (156 mg, 6.9 ꢂ 10ꢁ4 mol) was added to a solution con-
taining 300 mg (6.9 ꢂ 10ꢁ4 mol) of compound 3 and 20 mL of tol-
uene. The reaction mixture was protected from the light with
aluminium foil and refluxed for 3.5 h. During the reflux the depo-
sition of the metallic palladium on the walls of the flask was de-
tected. After this period the resulting hot solution was filtered
through 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 allowed to dry overnight and then it was washed with
CH2Cl2 until nearly colourless washings were obtained. The wash-
ings were collected in the same flask containing the residue and
the resulting solution was concentrated to dryness on a rotary
evaporator. The crude product thus obtained was dissolved in
20 mL of CH2Cl2 and treated with PPh3 (182 mg, 6.9 ꢂ 10ꢁ4 mol)
and the resulting reaction mixture was stirred for 1.5 h at room
temperature. It was then filtered and the filtrate was concentrated
to dryness on a rotary evaporator giving a brownish residue. This
was then suspended in 30 mL of acetone and treated with LiCl
(31 mg, 6.9 ꢂ 10ꢁ4 mol). The resulting suspension was stirred for
2.5 h at room temperature under argon atmosphere. The undis-
solved materials were removed by filtration and the filtrate was
concentrated to dryness on a rotary evaporator and then dried in
vacuum. The yellowish-brown residue was dissolved in minimum
0
0
0
00
0
00
0
0
6H, H3 , H4 , H5 , H3 , H4 and H5 ) and 7.65(d, 4H, J = 7.5, H2 , H6 ,
00
00
H2 and H6 ). 13C{1H} NMR data [48]: d = 23.8(–CH2–), 38.9(NMe),
66.7(C2Fc
,
C3Fc
,
C4Fc and C5Fc), 68.4(Cp), 88.8(C1Fc), 116.9(C4),
0
0
0
0
0
00
128.3(C2 and C6 ), 128.2(C3 and C5 ), 127.4(C4 ), 127.6(C4 ),
00
00
00
00
0
00
128.6(C3 and C5 ), 130.0(C2 and C6 ), 130.2(C1 ), 134.2(C1 ),
142.3(C5) and 149.3(C3).
3.2.4. Preparation of trans-[Pd{1-Me-3,5-Ph2-(C3N2)-CH2-Fc}2Cl2]
(4a)
Cis-[PdCl2(dmso)2] (260 mg, 7.8 ꢂ 10ꢁ4 mol) was suspended in
30 mL of methanol and refluxed until complete dissolution. Then
the hot solution was filtered directly on a solution containing
15.6 ꢂ 10ꢁ4 mol of 3 (672 mg) in 5 mL of methanol. The resulting
reaction mixture was refluxed for 2 h. The precipitate formed
was collected, washed with (2 ꢂ 5 mL) portions of methanol, air-
dried and then dried in vacuum for 2 days. Yield: 640 mg (79%).
Characterization data: Anal. Calc. for C54H50Cl2N4PdFe2: C, 62.12;
H, 4.83; N, 5.37. Found: C, 62.20; H, 4.91; N, 5.45%. MS (ESI+):
m/z = 1042.0 [M]+. IR: 1636(s), 150(m), 1479(m), 1246(s),
1224(m), 1077(m), 1024(m), 923(s), 827(m), 756(m), 70s0(w)
and 498(Pd–N) and 334(Pd–Cl) cmꢁ1
.
1H NMR data [48]:
d = 3.41(s, 4H, 2 –CH2–), 3.54(br., 4H, 2H3Fc and 2H4Fc), 3.84(s,
10H, 2 Cp), 3.89(br.s, 4H, 2 NMe), 3.88(br.s, 4H, H2Fc and H5Fc),
amount of CH2Cl2 and passed through
a
SiO2 column
0
00
3.80(br.s, 4H, H2Fc and H5Fc), 7.09–7.16(br. m, 4H, 2H4 and 2H4
)
(3.0 cm ꢂ 9.0 cm) using CH2Cl2 as eluant. After the removal of the
first band, that contained [PdCl2(PPh3)2], the eluted bands were
collected in ca. 100 mL portions. Then the bright yellow solutions
collected were concentrated to dryness on a rotary evaporator to
give 6a (425 mg, 74%). Characterization data: Anal. Calc. for
C45H38ClN2PFePd: C, 64.69; H, 4.55; N, 3.35. Found: C, 64.54; H,
4.62; N, 3.31%. MS (ESI+): m/z = 799.1 {[M]ꢁCl}+. Rf(CH2Cl2) = 0.31.
IR: 1671(w), 1591(m), 1479(m), 1434(s), 1367(m), 1314(w),
1271(w), 1095(s), 1017(m), 999(m), 818(m), 748(s), 725(m),
0
0
0
0
00
00
00
and 7.40–7.62(br. m. 16H, 2H2 , 2H3 , 2H5 , 2H6 , 2H2 , 2H3 , 2H5 and
00
2H6 ). 13C{1H} NMR data [48]: d = 23.5(–CH2–), 37.4(NMe), 67.0(C3Fc),
67.2(C4Fc), 68.4(C5Fc), 68.6(C2Fc and Cp), 87.4(C1Fc), 119.5(C4),
00
00
0
0
00
0
0
128.1(C5 ), 128.7(C4 ), 128.8(C3 , C5 and C3 ), 128.9(C4 ), 129.6(C1 ),
00
0
0
00
00
129.8(C6 ), 130.1(C2 and C6 ), 131.2(C2 ), 131.9(C1 ), 144.7(C5) and
150.9(C3).
3.2.5. Preparation of cis-[Pd{1-Me-3,5-Ph2-(C3N2)-CH2-Fc}Cl2(dmso)]
(5a)
709(s), 533(s), 515(s) and 494(m) cmꢁ1. UV–Vis (c = 1.6 ꢂ 10ꢁ4
M
[PdCl2(dmso)2] (260 mg, 7.8 ꢂ 10ꢁ4 mol) was suspended in
30 mL of methanol and refluxed until complete dissolution. Then
the hot solution was filtered directly on a solution containing
7.8 ꢂ 10ꢁ4 mol of 3 (337 mg) in 5 mL of methanol. The resulting
reaction mixture was refluxed for 2 h and then allowed to cool at
room temperature. The precipitate formed was collected by filtra-
tion, washed with (2 ꢂ 5 mL) portions of methanol and air-dried
for one day. After this period the solid was dissolved in the mini-
in CH2Cl2): k in nm (e
in Mꢁ1 cm2) = 242(25 256) and 437(192).
1H NMR data [48]: d = 3.80(s, 2H, –CH2–), 3.89(s, 5H, Cp), 3.97(s,
2H, H3Fc and H4Fc), 4.10(s, 2H, H2Fc and H5Fc), 4.33(s, 3H, –NMe),
00
00
6.47(td, 2H, J = 7.5 and 1.0, H5 ), 6.27(td, 1H, J = 7.5 and 1.0, H4 ),
00
0
0
0
0
00
6.82(d, 1H, J = 7.2, H3 ), 7.40-7.51 (br.m, 20H, H3 , H4 , H5 , H6 , H2
and aromatic protons of the PPh3 ligand) and 7.79(d, 2H, J = 7.6,
0
0
H2 and H2 ). 13C{1H} NMR data [48]: d = 23.8(–CH2–), 39.0(NMe),
66.9(C2Fc C3Fc C4Fc and C5Fc), 68.6(Cp), 87.6(C1Fc), 123.9(C4),
,
,

3640
P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
00
0
0
0
00
00
125.8(C4 ), 128.9(C3 and C5 ), 129.4(C4 ), 129.0(C3 ), 129.2(C5 ),
(ESI+): m/z = 794.1 {[M]+NH4}+. Rf(CH2Cl2) = 0.22. IR: 1637(s),
1502(w), 1445(m), 1379(m), 1311(w), 1147(s), 1105(w),
1023(m), 975(w), 822(s), 755(m), 700(s), 497(m), 440(m) and
348 and 312 (Pt–Cl) cmꢁ1. UV–Vis (c = 1.0 ꢂ 10ꢁ4 M in CH2Cl2): k
00
0
0
00
00
130.2(C2 ), 130.6(C2 and C6 ), 138.7(d, JC–P = 14, C6 ), 140.4(C1 ),
3
0
145.9(C5), 150.0(C3), 156.0(C1 ), and four additional doublets cen-
tred at ca. 128.1, 130.7, 131.3 and 135.0 due to due to the four
types of non-equivalent carbon-13 nuclei of the PPh3 ligand).
31P{1H} NMR data: d = 47.6.
in nm (e
in Mꢁ1 cm2) = 435(700), 239(26 656). 1H NMR data [48]:
d = 2.47(s, 3H, 3JH–Pt = 20.6 Hz, dmso) and 3.31(s, 3H,3JH–Pt = 20.3 Hz,
dmso), 3.62(s, 2H, –CH –), 3.69(s, 2H, H3Fc and H4Fc), 3.84(s, 5H, Cp),
2
00
3.2.7. Preparation of [Pt{
Fc}Cl(PPh3)] (6b)
This product was obtained using two different procedures
{methods (a) and (b)}.
Method (a): In this case compound 6b was prepared in NMR
scale and characterized in solution by 1H NMR. Compound 8b
(20 mg, 2.7 ꢂ 10ꢁ5 mol) and PPh3 (7 mg, 2.7 ꢂ 10ꢁ5 mol) were
introduced in a NMR tube and then 0.7 mL of CDCl3 was added.
It was shaken vigorously for 2 min. This produced a bright yellow
solution which gave the desired complex 6b in 84% yield (21 mg)
(after evaporation in vacuum).
j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-
3.88(s, 2H, H2Fc and H5Fc), 4.11(s, 3H, –NMe), 7.30(dd, 2H, H3 and
00
0
0
0
0
0
00
H5 ), 8.00(d, 2H, H2 and H6 ), 7.40-7.65(br. m, 6H, H3 , H4 , H5 , H2
,
00
00
H4 and H6
)
13C{1H} NMR data [48]: d = 23.7(–CH2–), 38.6(NMe),
42.1(dmso), 67.1(C3Fc and C4Fc), 68.3(C2Fc and C5Fc), 68.6(Cp), 87.5
0
0
00
00
(C1Fc), 119.3(C4), 126.5(C5 and C3 ), 127.6(C3 ), 128.3(C4 ),
0
0
0
0
0
0
0
0
128.9(C2 and C6 ), 129.7(C4 ), 129.9(C1 ), 130.1(C2 and C6 )
00
00
131.1(C1 , and C5 ), 145.1(C5) and 151.0(C3). 195Pt{1H} NMR data:
d = ꢁ2925 ppm.
3.2.9. Preparation of trans-[Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc}Cl2-
(dmso)] (7b)
Method (b): Ligand 3 (256 mg, 5.92 ꢂ 10ꢁ4 mol) and cis-[PtCl2
(dmso)2] (250 mg, 5.92 ꢂ 10ꢁ4 mol) were suspended in 20 mL tolu-
ene. Then, a solution containing 49 mg (5.92 ꢂ 10ꢁ4 mol) of sodium
acetate and 4 mL of methanol was added. The resulting reaction
mixture was refluxed for 54 h and then allowed to cool at room tem-
perature. The undissolved materials were removed by filtration and
the filtrate was concentrated to dryness on a rotary evaporator.
Afterwards, the deep-brown residue was dissolved in 20 mL of
CH2Cl2 and treated with 280 mg (8.8 ꢂ 10ꢁ4 mol) of PPh3. The
resulting reaction mixture was magnetically stirred at room tem-
perature for 1.5 h. It was then filtered and the filtrate was concen-
trated to dryness on a rotary evaporator. The deep-brown residue
was dissolved in the minimum amount of CH2Cl2 and passed
through a SiO2 column (3.0 cm ꢂ 9.0 cm) using CH2Cl2 as solvent.
The two bright yellow solutions collected were concentrated to
dryness on a rotary evaporator to give [PtCl2(PPh3)2] (100 mg) and
6b (275 mg, 50%), respectively.
This product was synthesized as described above for 5a, but
using 256 mg (5.92 ꢂ 10ꢁ4 mol) of ligand 3, and 250 mg (5.92 ꢂ
10ꢁ4 mol) of cis-[PtCl2(dmso)2]. Yield: 400 mg (87%). Characteriza-
tion data: Anal. Calc. for C29H30Cl2N2OPtFeS: C, 44.85; H, 3.87; N,
3.61; S, 4.12. Found: C, 44.87; H, 3.91; N, 3.77; S, 3.98%. MS
(ESI+): m/z = 799.0 {[M]+Na}+. Rf(CH2Cl2) = 0.11. IR: 1636(s),
1504(w), 1447(m), 1379(m), 1312(w), 1294(w), 1246(w),
1142(s), 1105(m), 1023(s), 763(m), 702(s), 494(m), 441(m) and
355 (Pt–Cl) cmꢁ1. UV–Vis (c = 1.6 ꢂ 10ꢁ4 M in CH2Cl2): k in nm (
e
in Mꢁ1 cm2) = 238(25 725), 313sh(1759) and 437(200). 1H NMR
3
data [48]: d = 3.44(s, 12H, JH–Pt = 20.4 Hz, dmso), 3.46(br., 4H,
–CH2–, H3Fc and H4Fc), 3.51(br., 2H, H2Fc and H5Fc), 3.84(s, 5H,
0
0
Cp), 4.13(s, 3H, –NMe), 7.30–7.48(br.m. 2H, H3 and H5 ), 7.45–
0
0
0
00
00
000
0
7.62(br. m, 6H, H3 , H4 , H5 , H2 , H4 , H6 ), 7.82(d, 2H, J = 7.6, H2
0
and H6 ). 13C{1H} NMR data [48]: d = 23.7(–CH2–), 38.6(NMe),
42.1(dmso), 67.3(C2Fc, C3Fc, C4Fc and C5Fc), 68.6(Cp), 87.5(C1Fc),
0
00
0
00
0
00
119.3(C4), 128.2(C3 , C3 and C5 ), 128.0(C5 ), 128.5(C4 ), 129.1(C4 ),
00
0
00
00
0
000
Characterization data: Anal. Calc. for C45H38ClN2PPtFe: C, 58.48;
H, 4.14; N, 3.03. Found: C, 58.31; H, 4.02; N, 3.16%. MS (ESI+): m/
z = 888.1 {[M]ꢁCl}+. Rf(CH2Cl2) = 0.71. IR: 1638(s), 1618(s),
1478(m), 1272(w), 1096(m), 1025(w), 999(w), 895(w), 819(m),
129.4(C2 and C6 ), 129.6(C2 and C6 ), 130.2(C1 ), 131.3(C1 ),
148.5(C5) and 152.0(C3). 195Pt{1H} NMR data: d = ꢁ3015 ppm.
3.2.10. Preparation of [Pt{j
2-C,N-[3-(C6H4)-1-Me-5-Ph-(C3N2)]-CH2-
Fc}Cl(dmso)] (8b)
745(s), 691(s), 542(s) and 481(m) cmꢁ1. UV–Vis (c = 1.6 ꢂ 10ꢁ4
M
in CH2Cl2): k in nm (
e
in Mꢁ1 cm2) = 242(30 150), 312(6219),
This product can be isolated by two different methods.
347sh(ꢃ2150) and 452broad (ꢃ165). 1H NMR data [48]:
d = 3.83(s, 2H, –CH2–), 3.89(s, 5H, Cp), 3.96(s, 2H, H3Fc and H4Fc),
4.00(s, 2H, H2Fc and H5Fc), 4.18(s, 3H, –NMe), 6.32(d, 1H, J = 7.2,
Method (a). Compound
3
(256 mg, 5.92 ꢂ 10ꢁ4 mol), cis-
[PtCl2(dmso)2] (250 mg, 5.92 ꢂ 10ꢁ4 mol) and 20 mL of toluene
were introduced in a 100 mL Erlenmeyer flask. Then, a solution
containing 49 mg (5.92 ꢂ 10ꢁ4 mol) of sodium acetate and 4 mL
of methanol was added. The reaction mixture was refluxed for
54 h and then allowed to cool at room temperature. The resulting
solution was filtered and the filtrate was concentrated to dryness
on a rotary evaporator giving a yellowish-brown residue, which la-
ter on was dissolved in the minimum amount of CH2Cl2 and passed
through a SiO2 column (3.0 cm ꢂ 9.0 cm) using CH2Cl2 as solvent,
and the eluted bands were collected in ca. 100 mL portions. The
first bright yellow solutions collected were concentrated to dry-
ness on a rotary evaporator to give 8b (77 mg) as yellow solid.
The orange fractions collected afterwards yielded, compound 7b
(285 mg) (molar ratio 7b:8b = 3.7:1.0).
00
00
H5 ), 6.63(td, 1H, J = 7.5 and 1.0, H4 ), 6.84(td, 2H, J = 7.5 and 1.0,
00
0
0
0
0
H3 ), 7.84(d, 1H, J = 7.5, H2 ), 7.32–7.64(br.m, 18H, H3 , H4 , H5
and aromatic protons of the PPh3). 13C{1H} NMR data [48]:
d = 23.7(–CH2–), 39.4(NMe), 39.8(dmso), 67.0(C2Fc, C3Fc,C4Fc and
0
0
0
C
5Fc), 68.6(Cp), 87.2(C1Fc), 123.2(C4), 130.7(C2 and C6 ), 120.4(C4 ),
0 0 00 00 00 00
128.7(C3 and C5 ), 124.2(C4 ), 129.5(C3 ), 129.3(C5 ), 130.6(C2 ),
00
00
139.8(C1 ), 138.1(d, JC–P = 9 and JC–Pt = 34, C6 ), 149.5(C3),
3
1
0
147.1(C5), 158.0(C1 ), and four additional doublets centred at ca.
128.0, 130.9, 131.0 and 135.1 due to the four types of non-
equivalent carbon-13 nuclei of the PPh3 ligand). 31P{1H} NMR
data: d = 25.6(1JPt–P = 4706). 195Pt{1H} NMR data: d = ꢁ4169 ppm
(1JPt–P = 4706 Hz).
Method (b). A mixture of trans-[Pt{1-Me-3,5-Ph2-(C3N2)-CH2-
Fc}Cl2(dmso)] (7b) (150 mg, 1.93 ꢂ 10ꢁ4 mol) and NaOAc (16 mg,
1.93 ꢂ 10ꢁ4 mol) in dry methanol (15 mL) was heated under reflux
for 30 h. The resulting solution was filtered and the filtrate was
concentrated to dryness on a rotary evaporator. The residue was
dissolved in minimum amount of CH2Cl2 and passed through a
SiO2 column (3.0 cm ꢂ 9.0 cm) using CH2Cl2 as eluant, and the
eluted bands were collected in ca. 100 mL portions. The bright yel-
low solutions collected were concentrated to dryness on a rotary
evaporator to give compounds 8b (10 mg) and 5b (125 mg) in a
3.2.8. Preparation of cis-[Pt{1-Me-3,5-Ph2-(C3N2)-CH2-Fc}Cl2(dmso)]
(5b)
It is basically the same as that described for compound 6b,
{method (b)}, (see above), except that in this case the refluxing per-
iod was decreased to 24 h to increase the yield of 5b. After the
work up of the column the amounts of the isolated compounds
were: 37 mg and 302 mg for 6b and 5b, respectively. Characteriza-
tion data: Anal. Calc. for C29H30Cl2N2OPtFeS: C, 44.85; H, 3.87; N,
3.61; S, 4.12. Found: C, 45.10; H, 3.89; N, 3.75; S, 3.92%. MS

P.K. Basu et al. / Journal of Organometallic Chemistry 694 (2009) 3633–3642
3641
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Dalton Trans. (1989) 1133–1138.
molar ratio of 5b:8b = 8.5:1.0. Characterization data: Anal. Calc. for
C29H29ClN2OPtFeS: C, 47.07; H, 3.95; N, 3.71; S, 4.33. Found: C,
47.24; H, 4.08; N, 3.66; S, 4.24%. MS (ESI+): m/z = 704.0
{[M]ꢁCl}+. Rf(CH2Cl2) = 0.44. IR: 1720(w), 1638(s), 1618(s),
1460(w), 1382(w), 1278(m), 1105(w), 1073(w), 1024(w), 912(w),
764(m), 697(s), 617(w) and 481(m) cmꢁ1. UV–Vis (1.6 ꢂ 10ꢁ4
M
in CH2Cl2):
k
in nm
(
e
in Mꢁ1 cm2) = 255(23 050) and
319sh(ꢃ2338). 1H NMR data [48]: d = 3.72(s, 2H, –CH2–), 3.83(s,
3
3H, JH–Pt = 20.7 Hz, dmso), 3.97(s, 2H, H3Fc and H4Fc), 3.93(s, 5H,
Cp), 3.97(s, 2H, H2Fc and H5Fc), 4.11(s, 3H, –NMe), 5.98(dd, 1H,
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Inorg. Chem. 46 (2007) 11202–11212;
00
00
J = 7.5 and 1.6, H5 ), 6.77td(1H, J = 7.5 and 1.0, H4 ), 6.94(td, 1H,
00
0
0
0
(b) A. Eisenwiener, M. Neuburger, T.A. Kaden, Dalton Trans. (2007) 218–233;
(c) A.V. Khripun, M. Haukka, V.Y. Kukushkin, Russ. Chem. Bull. 55 (2006) 247–
255;
(d) A.V. Khripun, S.I. Selivanov, V.Y. Kukushkin, M. Haukka, Inorg. Chim. Acta 359
(2006) 320–326;
7.5 and 1.0, H3 ), 7.42–7.60(br. m, 3H, H3 , H4 and H5 ), 7.83(d,
0
00
1H, 7.5 and 1.0, H2 ) and 7.89(dd, 1H, J = 7.5 and 1.0, H2 ), 7.52(m,
1H). 13C{1H} NMR data [48]: d = 23.3(–CH2–), 37.6(NMe), 38.6 and
38.9(dmso), 67.1(C2Fc C3Fc C4Fc and C5Fc), 68.5(Cp), 87.5(C1Fc),
, ,
(e) E. Ciesielska, A. Szulawska, K. Studzian, J. Ochocki, K. Malinowska, K. Kik, L.
Szmigiero, J. Inorg. Biochem. 100 (2006) 1579–1585;
0
0
0
0
0
0
0
119.8(C4), 128.6(C3 and C5 ), 127.5(C5 ), 127.9(C 4 ), 129.6(C4 ), 130.3
00
0
0
00
00
(C2 ), 130.7(C2 and C6 ), 139.2(C1 ), 144.2(C5), 145.0(C6 ,1JC–Pt = 31),
(f) K. Sakai, Y. Tomita, T. Ue, K. Goshima, M. Ohminato, T. Tsubomura,
K. Matsumoto, K. Ohmura, K. Kawakami, Inorg. Chim. Acta 297 (2000) 64–71.
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(2002) 201–210;
10
151.2(C3) and 158.4(C ).195Pt{1H} NMR data: d = ꢁ3383 ppm.
(b) X. Gai, R. Grigg, M.I. Ramzan, V. Sridharan, S. Collard, J.E. Muir, Chem.
Commun. (2000) 2053–2054;
Acknowledgements
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We are grateful to the Ministerio de Ciencia y Tecnología of Spain
and to the Generalitat de Catalunya for financial support (Grants:
CTQ2006-02390/BQU, CTQ2006-02007, CTQ2009-11501 (subpro-
gram BQU) and 2005SGR-0603). One of us (P.K.B.) is grateful to
Department of Science and Technology (New Delhi), Government of
India for providing post doctoral research fellowship under BOYS-
CAST Fellowship scheme 2006-07 and he dedicated this paper in
the memory of his late father.
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