Synthesis and coordination of the bifunctionalized ylides Ph2P(CH2)n(Ph)2P{double bond, long}CHCOOMe (n = 1, 2) and ketenylidene Ph2P(CH2)2(Ph)2P{double bond, long}C{double bond, long}C{double bond, long}O to Pd and Pt complexes

Article abstract of DOI:10.1016/j.ica.2007.10.055

In this paper it is reported the synthesis of the phosphonium salts [Ph₂P(CH₂)_n(Ph)₂PCH₂COOMe]Br (n = 1 (1), 2 (2)) and [Ph₂P(CH₂COOMe)(CH₂)_n(Ph)₂PCH₂COOMe]Br₂ (n = 3 (3)) derived from the reactions of the diphosphines dppm, dppe and dppp with methyl bromoacetate. By reaction of the monophosphonium salt of dppm and dppe with the strong base Na[N(SiMe₃)₂] the corresponding carbonyl stabilized ylides Ph₂P(CH₂)_n(Ph)₂P{double bond, long}CHCOOMe (n = 1 (4), 2 (5)) were obtained. The Ph₂P(CH₂)₂(Ph)₂P{double bond, long}CHCOOMe (5) ylide was reacted with Pd(II) and Pt(II) substrates. From these reactions were isolated exclusively complexes in which the ylide was chelated to the metal through the free phosphine group and the ylidic carbon atom. A further reaction of the Ph₂P(CH₂)₂(Ph)₂P{double bond, long}CHCOOMe (5) ylide with 1.5 equiv. of Na[N(SiMe₃)₂] gives the bifunctionalized ketenylidene Ph₂P(CH₂)₂(Ph)₂P{double bond, long}C{double bond, long}C{double bond, long}O (6) system. This cumulenic ylide reacts with Pt(II) complexes to form a chelated derivative in which IR and NMR spectra suggest the breaking of the C{double bond, long}C bond of the -C{double bond, long}C{double bond, long}O group.

Full text of DOI:10.1016/j.ica.2007.10.055

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 3177–3183
www.elsevier.com/locate/ica
Synthesis and coordination of the bifunctionalized ylides
Ph2P(CH2)n(Ph)2P@CHCOOMe (n = 1, 2) and ketenylidene
Ph2P(CH2)2(Ph)2P@C@C@O to Pd and Pt complexes
Silvia Mazzega Sbovata a, Augusto Tassan a, Giacomo Facchin b,*
a
`
Dipartimento dei Processi Chimici dell’Ingegneria, Universita di Padova, Via F. Marzolo, 9, I-35131 Padova, Italy
b
`
Istituto di Scienze e Tecnologie Molecolari, ISTM-CNR, c/o Dipartimento dei Processi Chimici dell’Ingegneria, Universita di Padova, Via F.
Marzolo, 9, I-35131 Padova, Italy
Received 29 September 2007; accepted 30 October 2007
Available online 13 February 2008
Dedicated to Professor Robert J. Angelici, in recognition of his many important contributions to the field of inorganic chemistry.
Abstract
In this paper it is reported the synthesis of the phosphonium salts [Ph2P(CH2)n(Ph)2PCH2COOMe]Br (n = 1 (1), 2 (2)) and
[Ph2P(CH2COOMe)(CH2)n(Ph)2PCH2COOMe]Br2 (n = 3 (3)) derived from the reactions of the diphosphines dppm, dppe and dppp with
methyl bromoacetate. By reaction of the monophosphonium salt of dppm and dppe with the strong base Na[N(SiMe3)2] the correspond-
ing carbonyl stabilized ylides Ph2P(CH2)n(Ph)2P@CHCOOMe (n = 1 (4), 2 (5)) were obtained. The Ph2P(CH2)2(Ph)2P@CHCOOMe (5)
ylide was reacted with Pd(II) and Pt(II) substrates. From these reactions were isolated exclusively complexes in which the ylide was che-
lated to the metal through the free phosphine group and the ylidic carbon atom. A further reaction of the Ph2P(CH2)2(Ph)2P@CHCO-
OMe (5) ylide with 1.5 equiv. of Na[N(SiMe3)2] gives the bifunctionalized ketenylidene Ph2P(CH2)2(Ph)2P@C@C@O (6) system. This
cumulenic ylide reacts with Pt(II) complexes to form a chelated derivative in which IR and NMR spectra suggest the breaking of the
C@C bond of the –C@C@O group.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: Ylides; Ketenylidene; Platinum complexes; Palladium complexes
1. Introduction
of the type Ph2P(CH2)n(Ph)2P@C@C@O functionalized
with a free phosphine. These systems, could potentially
give a more versatile reactivity than Ph3P@C@C@O
through the peculiar coordination ability of each group
to form different metallic derivatives with Pd(II) and Pt(II)
frameworks as depicted in Chart 1.
In this paper we report the one step synthesis of the
(Ph)2P(CH2)2(Ph)2P@C@C@O ylide starting from the
monophosphonium salt [Ph2PCH2CH2(Ph)2PCH2COO-
Me]Br by reaction with 2.5 equiv. of Na[N(SiMe3)2]. How-
ever, the same bifunctionalized ylide can be prepared also
step by step isolating first the carbonyl stabilized bifunc-
tional ylide Ph2P(CH2)2(Ph)2P@CHCOOMe by treatment
of the monophosphonium salt with an equivalent of
Na[N(SiMe3)2] and then by subsequent addition of further
The reactivity and coordination chemistry of carbonyl
stabilized [1] and bifunctionalized [2] ylides is an important
research field of our group. In recent years this area was
developed studying the organometallic chemistry of kete-
nylidenetriphenylphosphorane Ph3P@C@C@O towards Pt
substrates obtaining complexes in which the ylide was
r-bonded to the metal through the ylidic carbon atom
[3]. With the aim to expand this research theme, we have
examined the possibility to prepare and investigate the
chemistry of ketenylidenetriphenylphosphorane systems
*
Corresponding author. Tel.: +39 0498275516; fax: +39 0498275515.
E-mail address: giacomo.facchin@unipd.it (G. Facchin).
0020-1693/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.10.055

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S. Mazzega Sbovata et al. / Inorganica Chimica Acta 361 (2008) 3177–3183
as a single product also under more drastic experimental
conditions such as in the presence of a 10-fold excess of
methyl bromoacetate or carrying out the reaction at an
higher temperature or using different solvents than THF
such as chloroform or dichloromethane.
The analogous reaction between dppe, in which the two
phosphine groups are separated by a –CH2CH2– chain,
and 1 equiv. of methyl bromoacetate gives rise to a mixture
of the monophosphonium [Ph2PCH2CH2(Ph)2PCH2COO-
Me]Br (2) and diphosphonium [Ph2P(CH2COOMe)-
CH2CH2(Ph)2PCH2COOMe]Br2 salts in a ratio of ca. 4:1
as obtained by the integration of the corresponding signals
in the 31P NMR spectrum. This latter shows the character-
istic two doublets at 25.82 ppm and ꢀ12.25 ppm (3JP–P
=
43.73 Hz) relative to the monophosphonium salt and a sin-
glet at 26.80 ppm attributable to the diphosphonium com-
pound. This assignment was made by comparison with the
spectrum of a diphosphonium salt obtained by an indepen-
dent reaction between dppe and 2 equiv. of methyl bromo-
acetate. The monophosphonium salt can be easily
separated and purified from the diphosphonium salt by
treatment of the reaction mixture with ethanol in which
the diphosphonium salt is insoluble, while the disphospho-
nium could not be isolated in a pure form.
Chart 1.
1.5 equiv. of Na[N(SiMe3)2] to this carbonyl stabilized
ylide intermediate. The coordination chemistry of the ylide
Ph2P(CH2)2(Ph)2P@CHCOOMe with Pd and Pt complexes
and of (Ph)2P(CH2)2(Ph)2P@C@C@O with Pt complexes
was tested. In this latter case, surprisingly, the cumulenic
ylide coordinates in a chelating mode breaking the
–C@C@O system.
Finally, the reaction between dppp and methyl bromo-
acetate gives a mixture of mono- and diphosphonium salts
using amount of ester lower than 2 equiv. which we did not
succeed to separate. Such a mixture of salts was always
obtained under other different experimental conditions
such as, for example, at low temperature (ꢀ15 °C) or
changing the reaction solvents. In fact, the 31P NMR spec-
tra of the reaction products show always three singlets: one
at 24.02 ppm attributable to the diphosphonium salt, by
comparison with an independent preparation of this com-
pound, and two at 24.34 ppm and at ꢀ18.35 ppm for the
monophosphonium derivative. These results show that in
these reactions the two phosphine sites, which are sepa-
rated by the –CH2CH2CH2– group, have a reactivity inde-
pendent each other unlike that observed for dppm and
dppe. The only product of dppp, which was isolated in a
2. Results and discussion
2.1. Synthesis of the phosphonium salts
The preparation of the phosphonium salts of dppm,
dppe, dppp was carried out by reaction of the correspond-
ing diphosphine with methyl bromoacetate. However, from
these reactions different salts were obtained depending on
the diphosphine used as shown in Scheme 1.
The reaction with dppm, in which only one CH2 group
separates the two phosphorus atoms, gives exclusively the
monophosphonium bromide [Ph2PCH2(Ph)2PCH2COO-
Me]Br (1). This compound exhibits in the 31P NMR spec-
trum two doublets at 23.12 ppm and ꢀ26.66 ppm, with a
2
coupling constant JP–P of 64.35 Hz, attributable to the
phosphonium phosphorous and to the free phosphine
atoms, respectively. The H NMR spectrum shows a dou-
pure
form,
is
the
diphenylphosphonium
salt
1
[Ph2P(CH2COOMe)CH2CH2CH2(Ph)2PCH2COOMe]Br2
(3) obtained by reaction with an excess (>2 equiv.) of
methyl bromoacetate.
The different reactivity of the three diphosphines
towards the electrophilic addition of methyl bromoacetate
to form the corresponding phosphonium salts can be
blet at 5.12 ppm, with a 2JP–P of 13.34 Hz, relative to a CH2
group of a methoxycarbonylic system bonded to a phos-
phonium moiety [4] while the IR spectrum shows a strong
band at 1733 cmꢀ1 characteristic of a carbonylic group in a
phosphonium salt. The monophosphonium salt is obtained
Scheme 1.

S. Mazzega Sbovata et al. / Inorganica Chimica Acta 361 (2008) 3177–3183
3179
reasonably explained assuming that the transformation of
the first phosphine group into a phosphonium moiety can
influence the subsequent reactivity of the second phosphine
group. Such hypothesis is supported by the data reported
some years ago by Angelici et al. in a detailed paper regard-
ing the measurement of the basicity of a series of diphos-
phines by calorimetric determination of their DH of
protonation [5]. In this work it was demonstrated that there
is a linear correlation between the values of the DH of pro-
tonation of diphosphines and their pKa values as already
found in an analogous work regarding the monophos-
phines [6]. In particular, it was observed that, after the pro-
tonation of the first phosphine site (DHHP1), the value of
DHHP2 strongly depends on the length of the alkyl chain
that links the two phosphorous atoms. These results were
explained assuming that the electron-withdrawing effect
of the Ph2PH+ group, on the second phosphine system,
rapidly weakens upon increasing the CH2 groups between
the two phosphorous atoms of the diphosphine. In our
case, the alkylation of diphosphines with methyl bromo-
acetate can be seen similarly to the protonation reactions.
For the dppm the electron-withdrawing influence of the
monophosphonium cation is so strong that prevents the
reactivity of the second phosphine with methyl bromoace-
tate to give the diphosphonium derivative. This effect, how-
ever, shows a decreasing importance with the dppe and
dppp ligands so that the 1:1 reaction of the former diphos-
phine with methyl bromoacetate gives a mixture containing
the monophosphonium salt as the major product, while
dppp forms a more variable mixtures of the mono- and
diphosphonium derivatives together with unreacted start-
ing free diphosphine.
To prevent these problems and improve the synthesis of
these ylides, the deprotonation reaction of the phospho-
nium salt was carried out using Na[N(SiMe3)2] as a base
in a 1:1 ratio (see Section 3). The use of the strong base
Na[N(SiMe3)2] allows to perform the synthesis of the
carbonylic ylides derived from the monophosphonium salts
of dppm and dppe in a shorter time (ca. 10 min) with
respect to that required (2 h) using NEt3 and in higher
yields. The 31P NMR spectra of the obtained products
exhibit only the two doublets relative to the Ph2P-
(CH2)n(Ph)2P@CHCOOMe (n = 1 (4), 2 (5)) system. The
IR data confirm the complete formation of the carbonylic
ylides with the disappearance of the phosphonium CO
band at 1730 cmꢀ1 and the presence of a new strong CO
band relative to a carbonyl stabilized ylide at 1608 cmꢀ1
1
(n = 1) and 1607 cmꢀ1 (n = 2). Finally, the H NMR spec-
trum of 4 shows a doublet at 2.89 ppm attributable to the
2
ylidic proton with a coupling constant JH–P of 22.15 Hz.
On the contrary, for the ylide derived from the dppe, the
ylidic proton is masked by the –CH2CH2– group of the
diphosphine. The analogous reaction starting from the iso-
lated diphosphonium salt of the diphenylphosphinopro-
pane with 2 equiv. of Na[N(SiMe3)2], with the aim to
obtain the corresponding diylide, did not give a clean reac-
tion. This synthesis although carried out under different
experimental conditions (solvent, temperature, reaction
time), always shows, in the IR and NMR spectra, the for-
mation of complex mixtures in which are present various
species which could not be separated.
2.3. Synthesis of the ketenylidene Ph2PCH2CH2(Ph)2P@
C@C@O (6)
2.2. Synthesis of the carbonylic ylides
The synthesis of the ylide Ph2PCH2CH2(Ph)2P@C@
C@O (6) was carried out by reaction of the carbonyl stabi-
lized ylide 5 with 1.5 equiv. of Na[N(SiMe3)2] in a similar
manner to the procedure reported in the literature for the
preparation of Ph3P@C@C@O [8]. The progress of the
reaction was monitored by IR following the disappearance
of the carbonyl band at 1616 cmꢀ1 and the contemporary
formation of the new strong band due to the –C@C@O
moiety at 2103 cmꢀ1 in toluene. The 31P NMR spectrum
of 6 presents two doublets at 7.06 ppm and ꢀ12.47 ppm
attributable to the ylidic phosphorous and to free phos-
phine phosphorous atoms, respectively, with a coupling
The carbonylic ylides of the type Ph2P(CH2)n(Ph)2P@
CHCOOMe (n = 1 (4), 2 (5)) can be prepared starting from
the corresponding phosphonium salt by reaction with an
appropriate base. This synthesis was reported in the litera-
ture [7] and involves the reaction of the phosphonium salt
with a strong excess (10 equiv.) of NEt3. However, the use
of NEt3 as a base for the deprotonation of the phospho-
nium salt presents some problems regarding the purity of
the final ylide. The resulting product shows to be a mixture
formed mainly by the desired carbonylic ylide having a free
phosphine group and by a carbonylic ylide with the second
phosphine group oxidized to phosphine oxide. The forma-
tion of such a mixture is evidenced by 31P NMR. The
spectra show the characteristic doublets of the system
Ph2P(CH2)n(Ph)2P@CHCOOMe at ꢀ27.83 ppm and
15.76 ppm (2JP–P = 64.26 Hz) for the free phosphine and
ylidic phosphorous in the case of compound 4 and at
ꢀ12.14 ppm and 18.57 ppm (3JP–P = 48.18 Hz) for the free
phosphine and ylidic phosphorous in the case of compound
5. In addition, in both spectra is always present a doublet
due to the phosphine oxide at 29.32 ppm (4) and at
33.40 ppm (5).
3
constant JP–P of 48.96 Hz. The preparation of the keteny-
lidene 6 can be performed also starting directly from the
monophosphonium salt of dppe by adding to its toluene
suspension 2.5 equiv. of Na[N(SiMe3)2]. The spectroscopic
features of the product obtained by this reaction are iden-
tical to those of the same ylide obtained step by step start-
ing from the phosphonium salt through the carbonyl
stabilized ylide. The ketenylidene is very reactive and must
be managed with care. In chlorinated organic solvents it is
quickly protonated to form a mixture of the carbonyl
stabilized ylide and the corresponding phosphonium salt
probably due to the reaction with traces of HCl. In

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addition, in presence of traces of water, the spectroscopic
data of the mixture show more signals which can be
assigned to chemical species having a phosphine oxide
functionality.
[M(COD)Cl2] (M = Pd, Pt) and [Pt(CH3)(COD)Cl]. The
structure of the compounds obtained from these reactions
is reported in Fig. 1 and were characterized by IR and
31P NMR spectra.
Unlike the synthesis of Ph2PCH2CH2(Ph)2P@C@C@O
(6), the preparation of the ketenylidene derivatives derived
from the dppm and dppp presents various problems. In the
case of dppm, the reaction of the phosphonium salt or of
the corresponding carbonyl stabilized ylide with a suitable
amount of Na[N(SiMe3)2], did not give any evidence of the
formation of the ketenyl –C@C@O group. The reason can
be likely ascribed to the presence of two similar CH2 group
which can compete with the base in the deprotonation reac-
tion giving rise to different reactions. On the contrary,
reacting the diphosphonium salt of dppp with Na[N-
(SiMe3)2], also in excess of base, it was always obtained a
complex mixture that, on the basis of IR spectra, shows
to contain species with carbonyl and ketenyl groups. How-
ever, all attempts to separate these compounds failed.
The IR spectrum of 7, in Nujol, exhibits a CO band at
1694 cmꢀ1 in the typical range for the C-coordinated car-
bonyl ylides [4b]. The 31P NMR spectrum shows the pres-
ence of two set of signals, the first centred at 2.25 ppm, with
1
3
þ
a coupling constants JP–Pt of 3947.70 Hz and a JP–P of
17.99 Hz. The second set appears at 18.11 ppm with a cou-
2
þ–Pt
pling constant JP
of 129.5 Hz due to a phosphine and
to a ylidic phosphorous, respectively. A similar result is
obtained with the corresponding palladium complex (8):
the corresponding 31P NMR spectrum shows one doublet
at 21.78 ppm and the other at 25.22 ppm with a coupling
3
þ
constant JP–P of 24.5 Hz.
The analogous reaction carried out between
[Pt(CH3)(COD)Cl] and the bifunctional carbonyl stabilized
ylide gives rise to a mixture of two compounds (9a, 9b) in
both of which the ylide is chelated to the metal centre. The
31P NMR spectrum (see Section 3) suggests that the two
complexes differs only for the ancillary ligands on the plat-
inum as displayed in Scheme 2.
2.4. Reactivity of Ph2PCH2CH2(Ph)2P@CHCOOMe with
metal complexes
With the aim to investigate the reactivity of Ph2-
PCH2CH2(Ph)2P@CHCOOMe (5) towards metallic sub-
strates, we have reacted this ylide with the complexes
Such a reaction scheme is supported also by the reaction
of this mixture with PPh3. In fact, only one derivative (10)
was isolated having a structure with the chelated ylide, the
methyl and the triphenylphosphine groups coordinated to
the platinum atom (see Scheme 2).
2.5. Coordination of Ph2PCH2CH2(Ph)2P@C@C@O (6)
The Ph2PCH2CH2(Ph)2P@C@C@O (6) presents two
potentially sites of coordination towards a Pd(II) and Pt(II)
metal centre: (i) the phosphorous atom of the free phos-
phine and (ii) the ylidic carbon atom (see Chart 1, struc-
tures I and II).
Fig. 1. Structure of compounds 7–10.
Scheme 2.

S. Mazzega Sbovata et al. / Inorganica Chimica Acta 361 (2008) 3177–3183
3181
To test the reactivity of the ketenylidene 6 towards
metallic substrates we have carried out the reaction with
the cationic dimer [(dppe)Pt(l-Cl)]2[BF4]2. It was reported
that this dimer adds the ketenylide Ph3P@C@C@O [3c] giv-
ing a ylide metal–carbon r-bond complex. This compound
(11) exhibits in the IR spectrum a strong band –C@C@O at
2080 cmꢀ1 shifted 15 cmꢀ1 lower than the free ylide and in
the 31P NMR spectrum a signal at 27.79 ppm characteristic
of the ylidic phosphorous. The product obtained by the
reaction between [(dppe)Pt(l-Cl)]2[BF4]2 and the bifunc-
tionalized ylide Ph2PCH2CH2(Ph)2P@C@C@O does not
of the ylide with the cationic dimer of platinum previously
described. In particular, also in this case, we have observed,
in the IR spectrum in solution, the formation of the CO2
band at 2335 cmꢀ1 suggesting that the reaction proceeds
similarly to that reported above. These data seem to
indicate that during the coordination of the ylide to the
platinum centre, the ketenyl system undergoes the
same processes that give rise to the breaking of
the Cylide–Ccarbonyl bond with formation of CO2. A possible
mechanism of these processes could involve a nucleophilic
attack of traces of water, present in the solvent, to the car-
bonyl carbon of the ketenyl group, transfer of water hydro-
gen atoms to the ylidic carbon and subsequent formation
of CO2. In all these processes the platinum atom could play
a catalytic role.
show in the IR spectrum any band around 2100 cmꢀ1
,
attributable to a m(C@C@O) stretching, as well as, in the
range 1800–1600 cmꢀ1, indicating the presence of a CO
band characteristic of a carbonylic group. Moreover, fol-
lowing the reaction in CH2Cl2 solution by IR technique,
it was noted the rapid formation after the addition of the
ylide to the platinum dimer of a new band at 2335 cmꢀ1
which suggests the formation of CO2 [9]. The IR spectrum
of the isolated compound does not display bands at wave-
lengths characteristic for ketenyl or carbonyl stretchings as
well as in the range between 350 and 250 cmꢀ1 where usu-
ally fall the Pt–Cl bands [9]. In addition, in the 31C NMR
spectrum no signals appear at higher field indicating the
absence of carbonyl functionalities. Finally, the 31P NMR
spectrum shows an interesting pattern of signals which
allows to assign definitely the structure of this compound.
This spectrum exhibits two doublets at 50.73 ppm and
On this base we attribute to the complex (11) obtained in
the reaction between the [(dppe)Pt(l-Cl)]2[BF4]2 and the
ketenylidene Ph2PCH2CH2(Ph)2P@C@C@O the cyclic
structure reported in Fig. 2.
3. Experimental
3.1. General procedures
Manipulations were performed in typical Schlenk sys-
tems, under an atmosphere of dry nitrogen, and the pro-
gress of reactions was monitored by IR and NMR
spectroscopies. All solvents and reagents were used as pur-
chased without purification.
2
44.97 ppm with a coupling constant JP–P of 347.3 Hz
and 19.4 Hz each coupled with the platinum atom with a
1JP–Pt of 2404 Hz and 2288 Hz, respectively. These two
doublets can be assigned to the two coordinated diphos-
phine phosphorous atoms: the first to the Pa atom (see
Fig. 2) by its higher 2JP–P characteristic of two phosphorus
in trans position [10], the other to the phosphorous Pb
which is coupled with the cis phosphorous Pc. This Pc phos-
phorous atom shows a signal centred at 2.53 ppm which is
a doublet of doublets of doublets. In fact, it couples with
the two diphosphine atoms Pa and Pb, and also with the
phosphonium phosphorous atom with a coupling constant
IR spectra were taken by a FT-IR AVATAR 320 of the
Nicolet Instrument Corporation (4000–400 cmꢀ1) spectro-
1
photometer. H and 31P NMR spectra were run on a Bru-
ker 200 AC spectrometer operating at 200.133 and
81.015 MHz, respectively. The chemical shifts (d) are
referred to Me4Si (using the residual proton peaks of deu-
terated solvents) and to external 85% H3PO4. The elemen-
tal analyses were performed by the Microanalysis
Laboratory of the Department of Chemical Sciences, Uni-
versity of Padova.
The starting complex [PtCl2(COD)] [11], [PdCl2(COD)]
[12], [PtCl(COD)Me] [13] and [PtCl2(dppe)] [14] were pre-
pared according to published procedures.
of 2JPc–P ¼ 29:7 Hz. The phosphonium phosphorous atom
þ
2
signal at 20.82 ppm shows a JP–Pt of 79.0 Hz. A further
support regarding the coordination of Ph2PCH2CH2-
(Ph)2P@C@C@O to the ‘‘(dppe)Pt” metallic fragment to
give the chelated derivatives reported in Fig. 2, comes from
the reaction between the dicationic [(dppe)Pt(solv)2][BF4]2
complex with 1 equiv. of ketenylidene. The product of this
reaction shows the IR and 31P NMR spectroscopic data
identical to those of the derivative isolated in the reaction
The dimer [Pt(dppe)(l-Cl)]2[BF4]2 was obtained by stir-
ring a dichloromethane solution of [PtCl2(dppe)] with an
equivalent amount of AgBF4 (0.65 M in acetone) at room
temperature for 30 min. The resulting AgCl was removed
by filtration and [[Pt(dppe)(l-Cl)]2[BF4]2 was precipitated
with diethyl ether, filtered and dried under vacuum. The
complex [Pt(dppe)(solv)2][BF4]2 was prepared analogously
to the above derivative by reaction with 2 equiv. of AgBF4.
3.2. Synthesis of the phosphonium salts
3.2.1. [Ph2PCH2(Ph)2PCH2COOMe]Br (1)
To a suspension of Ph2PCH2PPh2 (1.00 g, 2.60 mmol) in
THF (20 ml) was added a-methylbromoacetate (0.26 ml,
2.65 mmol). After 10 min a white solid appeared and the
Fig. 2. Structure of compound (11).

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S. Mazzega Sbovata et al. / Inorganica Chimica Acta 361 (2008) 3177–3183
resulting suspension was stirred for 2 h. The mixture was
concentrated to about half of its initial volume and Et2O
was added to complete the precipitation. The white solid
was filtered, washed with Et2O (3 ꢁ 5 ml) and dried under
vacuum. Yield 1.36 g, 97%. Anal. Calc. for C28H27O2P2Br:
C, 62.58; H, 5.06. Found: C, 62.01; H, 5.26%. IR (Nujol):
3.3.2. [Ph2PCH2CH2(Ph)2P@CHCOOMe] (5)
This compound was synthetized following the procedure
described for the derivative 4. Yield 0.463 g, 65%. Anal.
Calc. for C29H32O2P2: C, 73.40; H, 6.80. Found: C,
73.65; H, 6.35%. IR (CH2Cl2): m(CO) 1615 cmꢀ1 1H
.
NMR (CDCl3): d = 2.23 (m, CH2), 2.61 (m, CH2), n.d.
m(CO) 1735 cmꢀ1. H NMR (CDCl3): d = 4.47 (dd, CH2,
(P@CH), 3.57 (s, OCH3). 31P NMR (CDCl3): d = 18.57
1
2
2
3
2JH–P 1.01 Hz, JHP 15.12 Hz), 5.16 (d, CH2, JH–P
(d, P, JP–P 48.18 Hz), ꢀ12.56 (d, P+).
13.34 Hz), 3.51 (s, OCH3). 31P NMR (CDCl3): d = 23.12
2
2
(d, JP–P 64.35 Hz ), ꢀ26.66 (d, JP–P 64.35 Hz).
3.4. Synthesis of the ketenylide
3.2.2. [Ph2PCH2CH2(Ph)2PCH2COOMe]Br (2)
3.4.1. [Ph2PCH2CH2(Ph)2P@C@C@O] (6)
Ph2P(CH2)2PPh2 (2.17 g, 5.45 mmol) was dissolved in
25 ml of THF and then a-methylbromoacetate (0.52 ml,
5.49 mmol) was added. After 10 min a white solid appeared
and the resulting suspension was stirred for 2 h. The mix-
ture was concentrated to about half of its initial volume
and Et2O was added to complete the precipitation. The
resulting solid is a mixture of mono- and diphosphonium
salts. The monophosphonium salt was separated by treat-
ment of the mixture with ethyl alcohol and filtration of
the insoluble diphosphonium salt; then the solution was
taken to dryness. Yield 1.52 g, 51%. Anal. Calc. for
C29H29O2P2Br: C, 63.17; H, 5.30. Found: C, 62.88; H,
To a suspension of compound 5 (0.467 g, 0.99 mmol) in
toluene were added NaN(SiMe3)2 (1.5 ml, 1.5 mmol) in
THF solution. After 3 h the yellow solution was filtered
under nitrogen to remove the NaOMe and concentrated
to a small volume (ca. 5 ml). n-Pentane was added and
the white precipitate was filtered, washed with n-pentane
(3 ꢁ 5 ml) and dried under vacuum. Yield 0.315 g, 72%.
Anal. Calc. for C28H24OP2: C, 76.70; H, 5.52. Found: C,
73.86; H, 5.35%. IR (CH2Cl2): m(CO) 2103 cmꢀ1 1H
.
NMR (CDCl3): d = 2.32 (m, CH2). 31P NMR (CDCl3):
3
d = 7.01 (d, P, JP–P 48.96 Hz), ꢀ12.47 (d, P+).
The ketenylide can be also obtained starting directly
from the monophosphonium salt (0.553 g, 1 mmol) by
reaction with 2.5 equiv. of NaN(SiMe3)2 in toluene follow-
ing the method described above. Yield 0.319 g, 72%.
1
5.51%. IR (Nujol): m(CO) 1723 cmꢀ1. H NMR (CDCl3):
2
d = 3.32 (m, CH2), 2.24 (m, CH2), 5.25 (d, CH2, JH–P
13.33 Hz), 3.50 (s, OCH3). 31P NMR (CDCl3): d = 25.82
2
2
(d, JP–P 43.73 Hz), ꢀ12.55 (d, JP–P 43.73 Hz).
3.5. Reactivity of the ylide Ph2P(CH2)2(Ph)2P@CHCOO-
Me (5) with transition metal complexes
3.2.3. [MeOOCCH2(Ph)2PCH2CH2CH2(Ph)2PCH2-
COOMe]Br2 (3)
To a suspension of dppp (0.424 g, 1.03 mmol) in THF
(20 ml) was added a-methylbromoacetate (0.25 ml,
2.64 mmol). The mixture was stirred for 12 h, than the
white precipitate was filtered, washed with Et2O
(3 ꢁ 5 ml) and dried under vacuum. Yield 0.735 g, 99%.
Anal. Calc. for C33H26O4P2Br2: C, 55.17; H, 5.05. Found:
3.5.1. Synthesis of [PtCl2(ylide)] (7)
To a solution of [PtCl2COD] (0.373 g, 0.40 mmol) in
25 ml of dichloromethane was added compound
5
(0.470 g, 0.40 mmol). The solution was stirred for 2 h at
room temperature, concentrated to a small volume (ca.
5 ml) and treated with n-hexane (ca. 30 ml) to afford a
white solid. The product was collected and dried under vac-
uum. Yield 0.246 g, 77%. IR (Nujol): m(CO) 1694 cmꢀ1. 1H
NMR (CD2Cl2): d = 2.3 (m, CH2), 3.31 (s, OCH3), 4.99 (m,
C, 55.48; H, 5.11%. IR (Nujol): m(CO) 1715 cmꢀ1 1H
.
NMR (CDCl3): d = 2.28 (m, CH2), 3.95 (m, CH2), 4.99
2
(d, CH2, JH–P 13.41 Hz) 3.51 (s, OCH3). 31P NMR
(CDCl3): d = 24.02 (s).
2
2
CH, JH–Pt 115.6 Hz, JH–P 5.5 Hz). 31P NMR (CD2Cl2):
1
3
3.3. Synthesis of the ylides
d = 2.25 (d, P, JP–Pt 3947.70 Hz, JP–P 17.99 Hz), 18.11
(d, P+, JP–Pt 129.5 Hz).
2
3.3.1. [Ph2PCH2(Ph)2P@CHCOOMe] (4)
To a suspension of the phosphonium salt 1 (0.538 g,
1.00 mmol) in toluene (25 ml) was added NaN(SiMe3)2
(1 ml, 1 mmol) in THF solution. The suspension was stir-
red for 10 min, then filtered to remove NaBr, concentrated
under vacuum to ca. 5 ml and treated with n-pentane. The
white solid obtained was filtered, washed with n-pentane
(3 ꢁ 5 ml) and dried under vacuum. Yield 0.343 g, 75%.
Anal. Calc. for C28H30O2P2: C, 73.03; H, 6.57. Found: C,
3.5.2. Synthesis of [PdCl2(ylide)] (8)
This product was synthetized as described for the com-
plex 7.Yield 0.240 g, 83%. IR (Nujol): m(CO) 1687 cmꢀ1
.
1H NMR (CD2Cl2): d = 2.3 (m, CH2), 3.34 (s, OCH3),
3
4.93 (s, CH). 31P NMR (CD2Cl2): d = 21.78 (d, P, JP–P
24.5), 25.22 (d, P+).
3.5.3. Synthesis of [PtCl(ylide)CH3] (9a) and
[Pt(solv)(Me)(ylide)] (9b)
The reaction was carried out as reported for compound
7. The product obtained results to be a mixture of
[PtCl(Me)(ylide)] (a) and [Pt(solv)(Me)(ylide)] (b). IR
1
73.65; H, 6.22%. IR (Nujol): m(CO) 1608 cmꢀ1. H NMR
2
(CDCl3): d = 3.54 (d, CH2, JH–P 13.83 Hz), 2.89 (d,
2
P@CH, JH–P 22.15 Hz), 3.53 (s, OCH3). 31P NMR
2
(CDCl3): d = 15.76 (d, P, JP–P 64.26 Hz), ꢀ27.83 (d, P+).

S. Mazzega Sbovata et al. / Inorganica Chimica Acta 361 (2008) 3177–3183
3183
(Nujol): m(CO) 1672 cmꢀ1. (a): 31P NMR (CD2Cl2):
(c) P. Uguagliati, L. Canovese, G. Facchin, L. Zanotto, Inorg. Chim.
Acta 192 (1992) 283;
(d) G. Facchin, L. Zanotto, R. Bertani, L. Canovese, P. Uguagliati, J.
Chem. Soc., Dalton Trans. (1993) 2871;
(e) L. Pandolfo, G. Facchin, R. Bertani, P. Ganis, G. Valle, Angew.
Chem., Int. Ed. Engl. 33 (1994) 576;
1
3
d = 12.64 (s, P, JP–Pt 4619.9 Hz, JP–P 12.2 Hz), 19.41 (s,
2
P+, JP–Pt 74.62 Hz). (b): 31P NMR (CD2Cl2): d = 2.24
1
3
(d, P, JP–Pt 4139.9 Hz, JP–P 18.8 Hz), 18.10 (d, P+,
2JP–Pt 83.8 Hz).
(f) R. Bertani, G. Cavinato, G. Facchin, L. Toniolo, A. Vavassori, J.
Organomet. Chem. 466 (1994) 273;
(g) L. Pandolfo, R. Bertani, G. Facchin, L. Zanotto, P. Ganis, G.
Valle, R. Seraglia, Inorg. Chim. Acta 237 (1995) 27;
(h) L. Pandolfo, G. Facchin, R. Bertani, P. Ganis, G. Valle, Angew.
Chem., Int. Ed. Engl. 35 (1996) 83;
(i) G. Facchin, L. Zanotto, R. Bertani, G. Nardin, Inorg. Chim. Acta
245 (1996) 157;
(j) U. Belluco, R.A. Michelin, R. Bertani, G. Facchin, G. Pace, L.
Zanotto, M. Mozzon, M. Furlan, E. Zangrando, Inorg. Chim. Acta
252 (1996) 355.
3.5.4. Synthesis of [Pt(PPh3)(ylide)CH3][Cl] (10)
The solution of the mixture 9 (100 mg) was treated with
triphenylphosphine in CH2Cl2. It was stirred for 2 h at
room temperature, concentrated to a small volume (ca.
5 ml) and precipitated with n-pentane (25 ml). The product
obtained was filtered, washed with n-pentane and dried
under vacuum. Yield 0.115 g, 71%. IR (Nujol): m(CO)
1
2
1682 cmꢀ1. H NMR (CD2Cl2): d = ꢀ0.13 (m, CH3, JH–
62.74 Hz), 2.3 (m, CH2), 2.96 (s, OCH3), 3.5 (m, CH).
[2] (a) G. Facchin, R. Campostrini, R.A. Michelin, J. Organomet. Chem.
294 (1985) C21;
Pt
1
31P NMR (CD2Cl2): d = 16.36 (d, P1, JP1–Pt 3031.71 Hz,
3
2
JP1–P2 7.75 Hz, JP1–PPh 419.47 Hz), 21.0 (dd, P+, JP–Pt
2
(b) R.A. Michelin, G. Facchin, D. Braga, P. Sabatino, Organome-
tallics 5 (1986) 2265;
(c) R.A. Michelin, M. Mozzon, G. Facchin, D. Braga, P. Sabatino, J.
Chem. Soc., Dalton Trans. (1988) 1803;
3
1
3
82.58 Hz, JP1–PPh 16.71 Hz), 33.77 (dd, PPh3, JP–Pt
3
2924.1 Hz).
(d) G. Facchin, M. Mozzon, R.A. Michelin, M.T.A. Ribeiro, A.J.L.
Pombeiro, J. Chem. Soc., Dalton Trans. (1992) 2827;
(e) U. Belluco, R.A. Michelin, R. Ros, R. Bertani, G. Facchin, M.
Mozzon, L. Zanotto, Inorg. Chim. Acta 198–200 (1992) 883;
(f) M.T.A. Ribeiro, A.J.L. Pombeiro, G. Facchin, M. Mozzon, R.A.
Michelin, Mol. Electrochem. Inorg. Bioinorg. Organomet. Compd.
385 (1993) 57;
(g) U. Belluco, R.A. Michelin, M. Mozzon, R. Bertani, G. Facchin,
L. Zanotto, L. Pandolfo, J. Organomet. Chem. 557 (1998) 37;
(h) M. Basato, G. Facchin, R.A. Michelin, M. Mozzon, S. Pugliese,
P. Sgarbossa, A. Tassan, Inorg. Chim. Acta 356 (2003) 349;
(i) M. Basato, F. Benetollo, G. Facchin, R.A. Michelin, M. Mozzon,
S. Pugliese, P. Sgarbossa, S. Mazzega Sbovata, A. Tassan, J.
Organomet. Chem. 689 (2004) 454;
3.6. Reactivity of ketenylide
3.6.1. {Pt(dppe)[(Ph)2P(CH2)2(Ph)2PCH2]} (11)
Method A. To a solution of [Pt(dppe)(l-Cl)]2[BF4]2
(0.198 g, 0.28 mmol) in 10 ml of CHCl3 was added drop-
wise a solution (5 ml) of ketenylylide Ph2P(CH2)2(Ph)2-
P@C@C@O (0.130 g, 0.30 mmol). The yellow solution
was stirred for 30 min, concentrated to a small volume
(3 ml) and the compound precipitated by addition of
Et2O. The yellow derivative was filtered off, washed with
Et2O (3 ꢁ 3 ml) and dried under vacuum. Yield 0.245 g,
87%. Anal. Calc. for C53H50P4Pt: C, 63.28; H, 5.01. Found:
(j) G. Facchin, R.A. Michelin, M. Mozzon, P. Sgarbossa, A. Tassan,
Inorg. Chim. Acta 357 (2004) 3385.
C, 62.88; H, 5.51%. 31P NMR (CDCl3): 44.97 (d, Pa, JP–P
2
[3] (a) L. Pandolfo, G. Paiaro, L.K. Dragani, C. Maccato, R. Bertani, G.
Facchin, L. Zanotto, P. Ganis, G. Valle, Organometallics 15 (1996)
3250;
1
2
19.41 Hz, JP–Pt 2404.5 Hz), 50.73 (d, Pb, JP–P 347.3 Hz,
1JP–Pt 2404.5 Hz), 2.53 (d, Pc, JP–P 19.41 Hz, JP–P
2
3
1
+
2
(b) F. Benetollo, R. Bertani, P. Ganis, L. Pandolfo, L. Zanotto, J.
Organomet. Chem. 629 (2001) 201;
þ–Pt
29.71 Hz, JP–Pt 2497.2 Hz), 20.82 (d, P , JP
79.0 Hz).
Method B. The complex [(dppe)Pt(solv)2]2[BF4]2
(0.256 g) was reacted with Ph2P(CH2)2(Ph)2P@C@C@O
(0.168 g, 0.38 mmol) in 15 ml of CHCl3. The mixture was
stirred for 30 min, concentrated to a small volume (ca.
3 ml) and precipitated with Et2O. The compound obtained
was filtered, washed with Et2O (3 ꢁ 3 ml) and dried under
vacuum. Yield 0.241 g. The spectroscopic data of the
obtained compound are identical to those of the above
derivative.
(c) R. Bertani, L. Pandolfo, L. Zanotto, Inorg. Chim. Acta 330 (2002)
213.
[4] (a) H.J. Bestmann, Angew. Chem., Int. Ed. Engl. 16 (1977) 349;
(b) A.W. Johnson, W.C. Kaska, K.A.O. Starzewski, D.A.
Dixon, Ylides and Imines of Phosphorus, Wiley, New York,
1993;
(c) O.I. Kolodazhnyi, Phosphorus Ylides, Wiley-VCH, Weinheim,
1999.
[5] J.R. Sowa, R.J. Angelici, Inorg. Chem. 30 (1991) 3534.
[6] R.C. Bush, R.J. Angelici, Inorg. Chem. 27 (1988) 681.
[7] Y. Oosawa, H. Urabe, T. Saito, Y. Sasaki, J. Organomet. Chem. 122
(1976) 113.
Acknowledgements
[8] H.J. Bestmann, D. Sandmeier, Angew. Chem., Int. Ed. Engl. 14
(1975) 634.
Financial support from CNR and the University of
Padova is acknowledged.
[9] L.J. Bellamy, Advance in Infrared Group Frequencies, Methuen,
London, 1968.
[10] T.G. Appleton, H.C. Clark, L.E. Manzer, Coord. Chem. Rev. 10
(1973) 335.
[11] P.B. Chock, J. Halpern, F.E. Paulik, Inorg. Synth. 14 (1973)
90.
[12] D. Drew, J.R. Doyle, Inorg. Synth. 13 (1972) 52.
[13] H.C. Clark, L.E. Manzer, J. Organomet. Chem. 59 (1973) 411.
[14] G. Booth, J. Chatt, J. Chem. Soc. A 1 (1966) 636.
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