Properties and catalytic activities of new easily-made amphiphilic phosphanes for aqueous organometallic catalysis

Article abstract of DOI:10.1002/adsc.201000014

Mono- and disulfonated amphiphilic versions of triphenylphosphane (PPh ₃) and cyclohexyl(phenyl)phosphane were easily synthesized from commercial reagents and sulfuric acid. The behaviour of these phosphanes in solution was investigated by surf

Full text of DOI:10.1002/adsc.201000014

FULL PAPERS
DOI: 10.1002/adsc.201000014
Properties and Catalytic Activities of New Easily-Made
Amphiphilic Phosphanes for Aqueous Organometallic
Catalysis
Michel Ferreira,a,b,f Hervꢀ Bricout,a,b,f Nathalie Azaroual,a,c,g Cꢀdric Gaillard,e
David Landy,a,d Sꢀbastien Tilloy,a,b,f and Eric Monfliera,b,f,
*
a
Universitꢀ Lille Nord de France, 59000 Lille, France
b
UArtois, UCCS, rue Jean Souvraz, 62300 Lens, France
Fax : (+33)-3-2179-1755; phone: (+33)-3-2179-1772; e-mail: eric.monflier@univ-artois.fr
UDSL, Facultꢀ de Pharmacie, BP 83, 59006 Lille, France
ULCO, LSOE, 145, Avenue Maurice Schumann, MREI 1, 59140 Dunkerque, France
INRA, UR1268 Biopolymꢁres Interactions Assemblages, BP 71 627, Rue de la Gꢀraudiꢁre, 44316 Nantes Cedex 3, France
CNRS, UMR 8181
c
d
e
f
g
CNRS, UMR 8009
Received: January 7, 2010; Revised: April 7, 2010; Published online: April 23, 2010
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.201000014.
Abstract: Mono- and disulfonated amphiphilic ver- formed well organized micelle-like aggregates while
sions of triphenylphosphane (PPh3) and cyclohexyl- the disulfonated phosphanes formed heterogeneous
ACHTUNGTRENNUNG(phenyl)phosphane were easily synthesized from and disorganized vesicle-like assemblies. The effi-
commercial reagents and sulfuric acid. The behav- ciency of these amphiphilic phosphanes was evaluat-
iour of these phosphanes in solution was investigated ed in the aqueous biphasic, palladium-catalyzed
by surface tension, isothermal titration calorimetry, cleavage of allyl alkyl carbonates.
nuclear magnetic resonance and cryo-transmission
electron microscopy. Two different supramolecular
assemblies were evidenced according to the degree Keywords: amphiphiles; aqueous-phase catalysis;
of sulfonation. The monosulfonated phosphanes phosphane ligands; Tsuji–Trost reaction; water
Introduction
amphiphilic phosphanes are often time-consuming, la-
borious and expensive. We have recently reported
During these last years, catalytic processes conducted that a highly water-soluble analogue of PPh3 can be
in biphasic aqueous media have garnered more and easily obtained by sulfonation of tris-
more attention. The main interest of aqueous biphasic
(biphenyl)phosphane.[4] Conceptually, this method
AHCTUNGTRENNUNG
catalysis is the attractive possibility to recover and to consists to introduce a phenyl group on each PPh3 ar-
recycle the transition metal by a simple decantation omatic ring and then to sulfonate it. The main interest
at the end of the reaction.[1] The transition metal is of this procedure is to perform the sulfonation reac-
contained in the aqueous phase by water-soluble li- tion under milder conditions compared to the classical
gands. The most widely widespread ligands are phos- conditions (concentrated oleum, elevated temperature
phanes possessing hydrophilic groups.[2] Nevertheless, and long reaction times) and so to avoid competitive
the main disadvantage of aqueous biphasic catalysis is oxidation of the phosphorus atom. Indeed, the sulfo-
the low reaction rates observed with hydrophobic sub- nation reaction takes place only on the activated aro-
strates. Among the various solutions to circumvent matic rings, i.e., on the phenyl groups which are not
this problem, the use of amphiphilic phosphanes is attached to the phosphorus atom. We report here that
very interesting because it simplifies the reaction our approach is also efficient to synthesize amphiphil-
system by incorporating the surface-active property ic versions of PPh3 and cyclohexylACTHNUTRGNE(UNG phenyl)phosphane
and the coordination ability towards the metal into (1, 2, 3 and 4) (Scheme 1). Their properties were stud-
the same compound.[3] Unfortunately, the syntheses of ied by measuring surface tension and self-diffusion
Adv. Synth. Catal. 2010, 352, 1193 – 1203
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1193

Michel Ferreira et al.
FULL PAPERS
Scheme 1. Structures of phosphanes 1, 2, 3 and 4.
coefficients; isothermal titration calorimetry (ITC), to the reaction medium to form the ammonium salt
and cryo-transmission electron microscopy analysis of the sulfonated phosphane.[5] This salt was recov-
were also performed. Finally, their behaviour was ex- ered by addition of chloroform and the resulting solu-
amined in the aqueous biphasic, palladium-catalyzed tion was washed with sodium hydroxide solutions to
cleavage of allyl alkyl carbonates.
give phosphanes 3 and 4 (yields: 70% and 65%, re-
spectively). Contrary to monosulfonated phosphanes,
addition of trioctylamine was required to obtain these
disulfonated phosphanes. Indeed, experiments have
shown that disulfonated phosphanes were more diffi-
Results and Discussion
The amphiphilic phosphanes 1–4 were synthesized in cult to isolate from the crude reaction mixture than
a two-step procedure (Scheme 2). Firstly, the reaction the monosulfonated phosphanes due to their more hy-
of biphenylmagnesium bromide with the appropriate drophilic character.
phosphorus chloride derivative gave the phosphanes
As expected, the disulfonated phosphanes 3 and 4
(para-PhPh)P(Cy)2, (para-PhPh)P(Ph)2, (para- are more water-soluble than the monosulfonated
PhPh)2PCy and (para-PhPh)2PPh. Each phosphane phosphanes 1 and 2. Indeed, the water solubilities of
was then dissolved in commercial sulfuric acid (96%). the phosphanes 1, 2, 3 and 4 at 258C are equal to
The reaction mixture was kept at room temperature 50 g/L, 280 g/L, 520 g/L and 850 g/L, respectively.
during 72 h under a nitrogen atmosphere. Phosphanes
1 and 2 were then obtained by addition of a sodium by measuring the JP,Se coupling constant of the sele-
The basicity of these phosphanes was determined
1
hydroxide solution (yields: 80% and 62%, respective- nides prepared from the reaction of the phosphanes
1
ly). For phosphanes 3 and 4, trioctylamine was added with elemental selenium.[6] The JP,Se coupling con-
Scheme 2. General procedure for the synthesis of phosphanes 1, 2, 3 and 4.
1194
asc.wiley-vch.de
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2010, 352, 1193 – 1203

Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes
stants for ligands 1, 2, 3 and 4 are equal to 707, 739,
Aggregation phenomena might also be studied by
734 and 739 Hz, respectively. The presence of elec- isothermal titration calorimetry (ITC), especially in
tron-withdrawing groups on phosphorus increases the the case of the formation of micelles.[7] Figure 2 de-
coupling constant whereas the presence of electron- scribes the ITC enthalpogram for dilution of phos-
donating groups decreases it. So, the replacement of a phanes 2 and 4 in water. On one hand, results for
phenyl group by an electron-donating cyclohexyl phosphane 2 are consistent with what could be ex-
group increases the basicity of the phosphanes 1 and pected for a surfactant: the whole enthalpy course
3 compared to 2 and 4. We can notice that the ligands consists of two horizontal parts connected by a sharp-
2 and 4 exhibit the same basicity indicating that a ly declining one. Indeed, before the phosphane CMC
para-PhPhSO3Na group has the same electronic influ- is reached inside the ITC cell, each enthalpy change
ence on the phosphorus atom as a phenyl group. is mainly due to total demicellization of injected
Indeed, the presence of an additional phenyl group phosphane and is thus nearly constant. Above the
on 4 counterbalanced the electron-withdrawing effect CMC, the energy change is principally resulting from
of the sulfonate group.
micellar dilution, which might be negligible if com-
The behaviour of these water-soluble phosphanes pared to demicellization and which might be consid-
was first investigated by surface tension measure- ered as constant. As a consequence, the difference be-
ments. The evolution of the surface tension (g) versus tween the final and initial linear parts of the enthalpo-
the phosphane concentration in water is presented in gram corresponds to the enthalpy of micellization:
the Figure 1. The profiles of the curves for the phos- DHmic is close to À4.7 kcalmolÀ1 for phosphane 2.
phanes 1 and 2 are typical of a surfactant since the Moreover, the intermediate region between these
surface tension showed a gradual decrease and re- linear parts allows the determination of the phos-
mained constant after the critical micellar concentra- phane CMC, defined as the midpoint of this transition
tion (CMC). The CMCs for phosphanes 1 and 2 are range. The plot of the heat second derivative against
equal to 0.4 and 0.6 mM, respectively. Surprisingly, for total phosphane concentration leads to a CMC value
the phosphanes 3 and 4, the surface tension gradually of 0.9 mM for phosphane 2, which is close to the
decreased until a break in the slope of the curve but value obtained by surface tension measurements. On
no plateau was observed. This breaking point in the the other hand, the enthalpogram of phosphane 4 is
surface tension profile was identified as a critical ag- rather different from the sigmoidal curve generally
gregation concentration (CAC). The CACs for phos- observed for a surfactant, since a continuous dimin-
phanes 3 and 4 are equal to 0.9 and 2.0 mM, respec- ishing heat is obtained. No horizontal part or point of
tively. These two different curve profiles are synony- inflexion is observed, whatever phosphane concentra-
mous of the formation of two kinds of aggregates ac- tion is employed in the syringe. If the important heats
cording to sulfonation degree. To better understand obtained during the titration demonstrate that inter-
the nature of these aggregates, phosphanes 2 and 4 molecular interactions occur, it seems that it does not
were chosen to be studied more deeply.
correspond to a classical demicellization process.
These ITC results confirm that the nature of the mo-
lecular assemblies is different for the phosphanes 2
and 4.
The self-diffusion coefficient by pulse-gradient
spin-echo NMR spectroscopy experiments (PGSE-
NMR) is also an appropriate technique for the study
of supramolecular assemblies.[8] We measured the
self-diffusion coefficient of aqueous solutions contain-
ing phosphanes 2 and 4 under and above the CMC
and CAC values (Table 1). In a solution in which the
solute does not associate, it is expected that the self-
diffusion coefficient will be independent of the con-
centration.[9] As it can be seen from Table 1, this is
not the case for the phosphanes 2 and 4 in D2O.
The value of self-diffusion coefficients decreased
from 3.62ꢃ10À10 m2 sÀ1 and 3.10ꢃ10À10 m2 sÀ1 at the
lowest concentration of 2 and 4 to 1.08ꢃ10À10 m2 sÀ1
and 1.97ꢃ10À10 m2 sÀ1 at the highest concentration of
2 and 4, respectively. This behaviour confirms that an
aggregation phenomenon occurs. Interestingly, the de-
crease is less important in the case of phosphane 4
suggesting the formation of less structured assemblies.
Figure 1. Surface tension curves of aqueous solutions of
phosphanes 1, 2, 3 and 4 at 258C.
Adv. Synth. Catal. 2010, 352, 1193 – 1203
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1195

Michel Ferreira et al.
FULL PAPERS
Figure 2. ITC raw heats (upper part) and ITC enthalpogram (lower part) of phosphane 2 (a) and phosphane 4 (b) dilution in
water at 258C.
Table 1. Self-diffusion coefficients of phosphanes 2 and 4 2 assemblies are clearly seen as relatively spherical-
measured by PGSE-NMR at 258C.
shaped dense assemblies (Figure 3, a, b, b’) while the
phosphane 4 assemblies appear as elongated and
often hollow structures with very weak density
(Figure 3, c, d, d’). The average particle sizes of phos-
phane 2 and phosphane 4 that were determined from
experimental size distributions were equal to 10.6Æ
5.6 nm and 13.4Æ8.1 nm, respectively.[11] Phosphane 4
samples display the higher mean diameter and the
morphologies of the assemblies are more lengthened
and heterogeneous. These observations undoubtedly
suggest that phosphanes 2 form well organized mi-
celle-like aggregates. In the case of phosphanes 4, the
structures are heterogeneous, disorganized and corre-
Phosphane Concentration
[mM]
Self-diffusion coefficient
[m2 sÀ1]
2
2
4
4
0.1[a]
5.0[b]
0.1[a]
5.0[b]
3.62ꢃ10À10
1.08ꢃ10À10
3.10ꢃ10À10
1.97ꢃ10À10
[a]
[b]
Under the CMC or CAC.
Above the CMC or CAC.
To investigate the size and morphology of the spond to vesicle-like assemblies.
formed aggregates, aqueous solutions of phosphanes 2 To investigate the effect of aggregate formation on
and 4 were studied by cryo-transmission electron mi- the reaction rate, the cleavage of allyl alkyl carbo-
croscopy (cryoTEM) which is now accepted as the nates (Tsuji–Trost reaction) was used as a model reac-
most useful tool for the direct imaging of self-aggre- tion.[12] The catalytic experiments were performed in
gation in aqueous systems.[10] For that, cryoTEM mi- an aqueous-organic two-phase system using Pd
ACHTUNGTRENNUNG(OAc)2
crographs series were recorded from vitreous thin as catalytic precursor at 258C. It is important to un-
films prepared by fast freezing of drops of the aque- derline that the phosphane concentration in the cata-
ous solution of phosphanes (Figure 3). These images lytic solution was sufficient to generate aggregates in
show nano-sized objects with a relatively narrow poly- solution (see Experimental Section for calculations).
dispersity that appear with a darker contrast as com- Allyl butyl carbonate (C4) and allyl undecyl carbonate
pared to the bright contrast of the surrounding solid (C11) were chosen as substrates to study the effect of
vitreous water. Specific morphologies can be deduced the chain length. Indeed, allyl butyl carbonate is more
from each cryoTEM image series and then related to soluble in the aqueous layer than allyl undecyl car-
the phosphane assemblies in solution. The phosphane bonate since its alkyl chain is shorter.
1196
asc.wiley-vch.de
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2010, 352, 1193 – 1203

Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes
Figure 3. Cryo-TEM of phosphane 2 (a, b) and phosphane 4 (c, d). (a) Typical raw cryo-TEM image of a vitreous thin film
from an aqueous dispersion of phosphane 2; (b) higher magnification view of a phosphane 2 vitreous thin film after contrast
enhancing with ImageJ. (c) Typical raw cryo-TEM image of a vitreous thin film from an aqueous dispersion of phosphane 4;
(d) higher magnification view of a phosphane 4 vitreous thin film after contrast enhancing with ImageJ. Insets (b’) and (d’)
show false-colour contrast-enhancing of a higher magnification zone of, respectively, images (b) and (d). The areas indicated
by c.f. on images (a) and (c) correspond to the holey carbon film support.
The conversions and the turnover frequencies sion after 1 h. A total conversion was obtained in 7,
(TOFs) obtained in the presence of these phosphanes 12, 17 and 30 min, for the phosphanes 1, 2, 3 and 4,
are presented in the Figure 4 and Table 2. For compa- respectively. The TOFs for the phosphanes 1, 2, 3 and
rative data, the same experiment was performed in 4 are 9.5, 8.2, 3.4 and 2.1 times higher than those ob-
the presence of the sodium salt of trisulfonated tri- served with TPPTS (Table 2). In the case of allyl un-
phenylphosphane (TPPTS). This ligand is non-amphi- decyl carbonate (Figure 4, b), the conversion was
philic and does not form aggregates.[3e,h] In the case of about 1% in the presence of TPPTS after 7 h of reac-
allyl butyl carbonate (Figure 4, a), the combination tion. In opposition, the complete conversion required
Pd/TPPTS allows the achievement of 100% conver- only 3 h in the presence of phosphane 1 as ligand. For
Adv. Synth. Catal. 2010, 352, 1193 – 1203
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1197

Michel Ferreira et al.
FULL PAPERS
the phosphanes 2, 3 and 4, conversions of 80%, 25%
and 15% were reached after 7 h. The TOFs for the
phosphanes 1, 2, 3 and 4 are 740, 160, 40 and 20 times
higher than those observed with TPPTS (Table 2).
These data indicate that the couple Pd/TPPTS allows
the realization of high conversion in the case of a par-
tially water-soluble substrate (allyl butyl carbonate)
whereas the conversion is very low with a substrate
that is insoluble in water (allyl undecyl carbonate). In
contrast, the cleavage reaction is always possible in
the presence of phosphane 1, 2, 3 or 4 whatever the
chain length of the substrate. This difference of be-
haviour can be illustrated by calculating for each
phosphane the ratio between the TOF obtained for
the cleavage of allyl butyl carbonate and that for allyl
undecyl carbonate (Table 2). This ratio is equal to
2200 in the case of TPPTS compared to 28, 113, 185
and 230 for the phosphanes 1–4, respectively. This de-
crease in activity is largely higher in the case of
TPPTS compared to the four amphiphilic phosphanes.
All these data confirm that, contrary to TPPTS, the
phosphanes 1–4 are still efficient with a highly hydro-
phobic substrate. Indeed, it was already demonstrated
that in the case of allyl undecyl carbonate, the limit-
ing step of this reaction is the mass transfer.[13] The
presence of these amphiphilic phosphanes 1–4 in-
creases the compatibility between the organic and
aqueous phases. However, it is worth mentioning that
the formation of a stable emulsion was observed in
the presence of phosphanes 1 and 2, so preventing the
recyclability of the catalytic system. Contrariwise, the
use of phosphanes 3 and 4 as ligands allowed an easy
separation of the two phases. Indeed, the slight emul-
sion observed between the two layers quickly disap-
peared when the stirring was stopped. So, among the
four phosphanes synthesized, the disulfonated phos-
phanes (3 and 4) appear as the best candidates for
aqueous organometallic catalysis since no emulsion
was observed at the end of the reaction.
Figure 4. Allyl alkyl carbonate conversion using phosphanes
1, 2, 3, 4 or TPPTS as ligand.
Conclusions
Table 2. TOF and ratio of TOF for phosphane 1, 2, 3, 4 and
TPPTS.
Amphiphilic
phenyl-
or
cyclohexylACTHNGUTRENNU(G biphenyl)-
phosphanes were easily synthesized from their hydro-
phobic equivalents by only using concentrated sulfuric
acid. The monosulfonated phosphanes are able to
form small micelle-like assemblies whereas the disul-
fonated ones form vesicle-like assemblies. The effi-
ciency of these amphiphilic phosphanes was proven in
the aqueous biphasic, palladium-catalyzed cleavage of
allyl alkyl carbonates. The disulfonated phosphanes
allowed the realization of high catalytic activity while
no emulsion appeared. These two last phosphanes are
good partners for aqueous organometallic catalytic
processes. Finally, it is also important to underline
that these ligands formed less widespread vesicle-like
Ligand TOF (C4)[a] TOF (C11)[a] Ratio TOF (C4)/TOF
[hÀ1]
[hÀ1]
(C11)[b]
1
2
3
4
2100
1800
740
74
16
4
2
0.1
28
113
185
230
2200
460
TPPTS 220
[a]
Initial TOF calculated for the cleavage of allyl butyl car-
bonate (C4) or allyl undecyl carbonate (C11).
Ratio between the TOF obtained for the cleavage of allyl
butyl carbonate (C4) and the TOF obtained for the cleav-
age of allyl undecyl carbonate (C11).
[b]
1198
asc.wiley-vch.de
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2010, 352, 1193 – 1203

Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes
(d, 3JP,C =6.8 Hz, C-7), 127.47 (s, C-10), 127.85 (s, C-12),
assemblies. Experiments are currently in progress to
induce a specific selectivity during aqueous organo-
metallic catalytic processes on the basis of these par-
ticular assemblies.
129.21 (s, C-11), 133.93 (d, 1JP, C =17.4 Hz, C-5), 135.58 (d,
2JP, C =18.9 Hz, C-6), 141.10 (s, C-8), 141.78 (s, C-9); 31P{1H}
NMR (121.5 MHz, CDCl3, 258C): d=3.38 (s).
The phosphane (para-PhPh)P(Cy)2 (4.2 g, 12 mmol) was
dissolved in 13 mL of commercial sulfuric acid (96%,
235 mmol, large excess) cooled by an ice bath. The reaction
mixture was then kept at room temperature for 72 h under a
nitrogen atmosphere. A 1N sodium hydroxide solution was
then added in the mixture, cooled by an ice bath, up to neu-
tral pH. During introduction of the sodium hydroxide solu-
tion, a precipitate appeared. After filtration and two wash-
ings with ice-cold water, phosphane 1 was obtained as a
white solid and dried under vacuum; yield: 80%.
Experimental Section
General Remarks
1
The H, 13C and 31P NMR spectra were recorded at 300.13,
75.47 and 121.49 MHz on a Bruker Avance DRX spectrom-
eter, respectively. Mass spectra were recorded on a MALDI
TOF TOF Bruker Daltonics Ultraflex II. Gas chromato-
graphic analyses were carried out on a Shimadzu GC-17A
gas chromatograph equipped with a methyl silicone capillary
column (30 mꢃ0.25 mmꢃ0.25 mm) and a flame ionization
detector (GC:FID).
D2O (99.95% isotopic purity) was obtained from Merck.
All reactants were purchased from Aldrich Chemicals or
Acros in their highest purity and used without further purifi-
cation. Distilled deionized water was used in all experi-
ments. All solvents and liquid reagents were degassed by
bubbling N2 for 15 min before each use or by two freeze-
pump-thaw cycles before use.
1H NMR (300 MHz, D2O, 25 8C): d=0.2–2.0 (broad m,
22H, H-1, H-2, H-2’, H-3, H-3’, H-4), 6.75–7.40 (broad s,
6H, H-6, H-7, H-10), 7.4–7.8 (broad s, 2H, H-11); 13C{1H}
2
NMR (75.5 MHz, DMSO, 258C): d=26.22 (d, JP, C
=
25.9 Hz, C-3, C-3’), 26.42 (d, 3JP, C =26.4 Hz, C-2 or C-2’),
Phosphane Synthesis
1
3
27.61 (s, C-1), 28.57 (d, JP, C =3.9 Hz, C-4), 29.79 (d, JP, C
=
All NMR spectra are available in the Supporting Informa-
tion.
21.4 Hz, C-2 or C-2’), 127.20 (s, C-11), 127.32 (s, C-10),
3
2
128.16 (d, JP, C =10.6 Hz, C-7), 135.79 (d, JP,C =12.8 Hz, C-
6), 139.67 (s, C-8 and C-9), 144.01 (broad s, C-5), 148.59 (s,
C-12); 31P{1H} NMR (121.5 MHz, D2O, 25 8C): d=0.42 (s).
MS (MALDI-TOF): m/z=431.08 [PÀNa+2H]+, 453.08
[P+H]+, 475.04 [P+Na]+, 491.11 [P+K]+.
Phosphane 1
A solution of 4-bromobiphenyl (4.8 g, 21 mmol) in anhy-
drous THF (40 mL) was added dropwise to magnesium turn-
ings (0.6 g, 24 mmol, 1.2 equiv.). After the addition was com-
pleted, the reaction mixture was heated under reflux for 1
hour. After cooling, dicyclohexylphosphorus chloride (4.8 g,
21 mmol, 1 equiv.) in THF (10 mL) was added dropwise and
the medium was then heated under reflux for 1 hour. The
mixture was poured into a mixture of ice (10 g) and water
(10 mL). The organic phase was concentrated by rotary
evaporation and the resulting solid was recrystallized from
methanol-THF mixture to give (para-PhPh)P(Cy)2 as white
crystals; yield: 70%.
Phosphane 2
A solution of 4-bromobiphenyl (25 g, 107 mmol) in anhy-
drous THF (190 mL) was added dropwise to magnesium
turnings (3.1 g, 129 mmol, 1.2 equiv.). After the addition was
completed, the reaction mixture was heated under reflux for
1 hour. After cooling, diphenylphosphorus chloride (23.7 g,
107 mmol, 1 equiv.) in THF (30 mL) was added dropwise
and the medium was then heated under reflux for 1 hour.
The mixture was poured into a mixture of ice (40 g) and
water (40 mL). The organic phase was concentrated by
rotary evaporation and the resulting solid was recrystallized
from methanol-THF mixture to give (para-PhPh)P(Ph)2 as
white crystals; yield: 51%.
1H NMR (300 MHz, CDCl3, 258C): d=0.90–1.50 (m,
11H) and 1.50–2.10 (m, 11H) (H-1, H-2, H-2’, H-3, H-3’, H-
3
3
4), 7.36 (t, JH,H =7.3 Hz, 1H, H-12), 7.46 (t, JH,H =7.3 Hz,
2H, H-11), 7.51–7.68 (m, 6H, H-6, H-7, H-10); 13C{1H}
NMR (75.5 MHz, CDCl3, 258C): d=26.86 (s, C-1), 27.46 (d,
1H NMR (300 MHz, CDCl3, 258C): d =7.35–7.52 (m,
3JP, C =7.4 Hz, C-2 or C-2’), 27.70 (d, JP,C =12.45 Hz, C-3 or
C-3’), 29.25 (d, JP, C =7.2 Hz, C-2 or C-2’), 30.47 (d, JP, C
16.1 Hz, C-3 or C-3’), 32.92 (d, JP, C =11.4 Hz, C-4), 126.87
2
3
2
3
=
15H, H-1, H-2, H-6, H-7, H-10, H-11, H-12), 7.63 (t, JH,H
=
1
2JH,P =6.3 Hz, 4H, H-3); 13C{1H} NMR (75.5 MHz, CDCl3,
Adv. Synth. Catal. 2010, 352, 1193 – 1203
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1199

Michel Ferreira et al.
FULL PAPERS
3
258C): d =127.50 (s, C-1), 127.56 (s, C-10), 127.66 (s, C-11),
127.99 (s, C-12), 128.99 (d, 3JP, C =6.7 Hz, C-2), 129.24 (d,
3JH,H =7.2 Hz, 2H, H-12), 7.46 (t, JH,H =7.2 Hz, 4H, H-11),
7.58–7.65 (m, 12H, H-6, H-7, H-10); 13C{1H} NMR
(75.5 MHz, CDCl3, 258C): d=26.40 (s, C-1), 26.87 (d, JP, C
11.25 Hz, C-2), 29.66 (d, JP, C =15.2 Hz, C-3), 35.58 (d, JP, C
8.7 Hz, C-4), 127.04 (d, JP,C =7.8 Hz, C-7), 127.09 (s, C-10),
3
2
3JP, C =2.9 Hz, C-7), 134.19 (d, JP,C =19.6 Hz, C-3), 134.54 (d,
=
=
2
1
2JP, C =19.6 Hz, C-6), 136.70 (d, 1JP, C =10.6 Hz, C-5), 137.54
(d, 1JP, C =10.3 Hz, C-4), 140.91 (s, C-8), 141.91 (s, C-9);
31P{1H} NMR (121.5 MHz, CDCl3, 258C): d =À4.89 (s).
The phosphane (para-PhPh)P(Ph)2 (5 g, 15 mmol) was dis-
solved in 15 mL of commercial sulfuric acid (96%,
270 mmol, large excess) cooled by an ice bath. The reaction
mixture was then kept at room temperature for 72 h under a
nitrogen atmosphere. A 3N sodium hydroxide solution was
then added in the mixture, cooled by an ice bath, up to neu-
tral pH. After complete rotary evaporation, the phosphorus
derivative was extracted by methanol on the obtained solid.
Rotary evaporation followed by recrystallization in an etha-
nol-methanol mixture gave phosphane 2 as a white solid,
yield: 62%.
3
2
127.51 (s, C-12), 128.84 (s, C-11), 134.15 (d, JP, C =18.7 Hz,
1
C-6), 135.98 (d, JP, C =13.9 Hz, C-5), 140.62 (s, C-8), 141.41
(s, C-9); 31P{1H} NMR (121.5 MHz, CDCl3, 258C): d=À5.31
(s).
The phosphane (para-PhPh)2PCy (5 g, 12 mmol) was dis-
solved in 15 mL of commercial sulfuric acid (96%,
270 mmol, large excess) cooled by an ice bath. The reaction
mixture was then kept at room temperature for 72 h under a
nitrogen atmosphere. The medium was poured into a mix-
ture of water and ice (150 mL/150 g), and trioctylamine
(8.6 g, 24 mmol, 2.04 equiv.) was then added. The ammoni-
um salt of the sulfonated phosphane was recovered from the
acidic aqueous layer by addition of chloroform (100 mL)
and the organic layer was washed with water up to neutral
pH. The sodium salt was recovered by a succession of ex-
tractions with NaOH aqueous solution (0.2N). Each fraction
(5 mL) was analyzed by 31P{1H} NMR spectroscopy and the
fractions where a unique signal was observed were com-
bined and washed by chloroform. Phosphane 3 was obtained
after rotary evaporation as a white solid; yield: 70%.
1H NMR (300 MHz, D2O, 25 8C): d=6.4–6.9 (broad m,
3
16H, H-1, H-2, H-3, H-6, H-7, H-10), 7.35 (d, JH,H =7.5 Hz,
2H, H-11); 13C{1H} NMR (75.5 MHz, DMSO-d6, 258C): d=
3
126.92 (s, C-10), 127.07 (s, C-11), 127.88 (d, JP, C =6.8 Hz, C-
3
7), 129.81 (d, JP, C =6.8 Hz, C-2), 129.92 (s, C-1), 134.16 (d,
2JP, C =19.6 Hz, C-3), 134.70 (d, 2JP, C =19.6 Hz, C-6), 136.73
(d, 1JP, C =11.3 Hz, C-5), 137.42 (d, 1JP, C =11.3 Hz, C-4),
140.17 (s, C-8), 141.01 (s, C-9), 148.53 (s, C-12); 31P{1H}
NMR (121.5 MHz, D2O, 25 8C): d=À5.96 (s); MS (MALDI-
TOF): m/z=440.87 [P+H]+, 462.86 [P+Na]+.
1H NMR (300 MHz, D2O, 25 8C): d=0.98 (broad s, 5H)
and 1.46 (broad s, 5H) (H-1, H-2, H-3), 2.02 (broad s, 1H,
3
H-4), 7.10 (d, 3JH,H =8.1 Hz, 4H, H-10), 7.15 (d, JH,H
=
7.5 Hz, 4H, H-7), 7.27 (t, 3JH,H =3JP, H =7.5 Hz, 4H, H-6),
7.61 (d, JH,H =8.1 Hz, 4H, H-11); 13C{1H} NMR (75.5 MHz,
3
Phosphane 3
D2O, 25 8C): d=26.68 (broad s, C-1, C-2), 29.53 (broad s, C-
A solution of 4-bromobiphenyl (12.6 g, 54 mmol) in anhy-
drous THF (100 mL) was added dropwise to magnesium
turnings (1.6 g, 64 mmol, 1.2 equiv.). After the addition was
completed, the reaction mixture was heated under reflux for
3), 34.68 (s, C-4), 125.81 (s, C-11), 126.73 (s, C-10), 126.96
1
(d, C-7), 133.71 (d, 2JP, C =18.6 Hz, C-6), 136.67 (d, JP, C
=
15.3 Hz, C-5), 139.51 (s, C-8), 141.49 (s, C-9), 142.02 (s, C-
12); 31P{1H} NMR (121.5 MHz, D2O, 25 8C): d=À6.49 (s).
MS (MALDI-TOF): m/z=602.95 [P+2HÀNa+]+, 625.06
[P+H]+, 647.02 [P+Na]+, 1271.03 [2P+Na]+.
1
hour. After cooling, cyclohexylphosphorus dichloride
(5.0 g, 27 mmol, 0.5 equiv.) in THF (10 mL) was added drop-
wise and the medium was then heated under reflux for 1
hour. The mixture was poured into a mixture of ice (20 g)
and water (20 mL). The organic phase was concentrated by
rotary evaporation and the resulting solid was recrystallized
from methanol-THF mixture to give (para-PhPh)2PCy as
white crystals; yield: 84%.
Phosphane 4
A solution of 4-bromobiphenyl (25 g, 107 mmol) in anhy-
drous THF (190 mL) was added dropwise to magnesium
turnings (3.1 g, 129 mmol, 1.2 equiv.). After the addition was
completed, the reaction mixture was heated under reflux for
1 hour. After cooling, phenylphosphorus dichloride (9.6 g,
54 mmol, 0.5 equiv.) in THF (15 mL) was added dropwise
1H NMR (300 MHz, CDCl3, 258C): d=1.32 (m, 5H) and
1.80 (m, 5H) (H-1, H-2, H-3), 2.30 (m, 1H, H-4), 7.37 (t,
1200
asc.wiley-vch.de
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2010, 352, 1193 – 1203

Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes
and the medium was then heated under reflux for 1 hour.
The mixture was poured into a mixture of ice (40 g) and
water (40 mL). The organic phase was concentrated by
rotary evaporation and the resulting solid was recrystallized
from methanol-THF mixture to give (para-PhPh)2PPh as
white crystals; yield: 44%.
gently stirred for 30 s. Surface tension was measured for
each concentration. The temperature stabilization can be es-
timated as better than Æ0.058C with a thermoregulated
bath Lauda RC6.
NMR Self-Diffusion Coefficient
1H NMR (300 MHz, CDCl3, 258C): d =7.35–7.60 (m,
12H, H-2, H-3, H-7, H-10), 7.60–7.67 (m, 7H, H-1, H-11, H-
12), 7.72–7.86 (m, 4H, H-6); 13C{1H} NMR (75.5 MHz,
CDCl3, 258C): d =127.46 (s, C-1), 127.56 (s, C-10), 127.65 (s,
The self-diffusion coefficients were determined by the
PGSE-NMR technique on a Bruker Avance 500 spectrome-
ter equipped with a TXI probe at 258C. The field gradient
was varied from 1 to 35 GcmÀ1 and the parameters gradient
pulse duration (d) and diffusion times (D) have been adjust-
ed (d=6 ms and D=150 ms) in order to obtain a full de-
cease of the spin echo signal. The field gradient was calibrat-
ed with the diffusion of H2O in H2O/D2O mixtures. For the
two concentrations 0.1 mM and 5 mM, 24 experiments were
realized with 256 and 608 accumulations, respectively.
3
C-11), 127.96 (s, C-12), 128.98 (d, JP, C =6,7 Hz, C-2), 129.22
2
(s, C-7), 134.13 (d, 2JP, C =19.6 Hz, C-3), 134.57 (d, JP, C
=
19.6 Hz, C-6), 136.35 (d, 1JP, C =10.6 Hz, C-5), 137.45 (d,
1JP, C =10.3 Hz, C-4), 140.87 (s, C-8), 141.92 (s, C-9); 31P{1H}
NMR (121.5 MHz, CDCl3, 258C): d =À5.67 (s).
The phosphane (para-PhPh)2PPh (5 g, 12 mmol) was dis-
solved in 15 mL of commercial sulfuric acid (96%,
270 mmol, large excess) cooled by an ice bath. The reaction
mixture was then kept at room temperature for 72 h under a
nitrogen atmosphere. The medium was poured into a mix-
ture of water and ice (150 mL/150 g), and trioctylamine
(8.7 g, 25 mmol, 2.04 equiv.) was then added. The ammoni-
um salt of the sulfonated phosphane was recovered from the
acidic aqueous layer by addition of chloroform (100 mL)
and the organic layer was washed with water up to neutral
pH. The sodium salt was recovered by a succession of ex-
tractions with NaOH aqueous solution (0.2N). Each fraction
(5 mL) was analyzed by 31P{1H} NMR spectroscopy and the
fractions where a unique signal was observed were com-
bined and washed by chloroform. Phosphane 4 was obtained
after rotary evaporation as a white solid; yield: 65%.
ITC Measurements
An isothermal calorimeter (ITC200, MicroCal Inc., USA)
was used for determining simultaneously the CMC and mi-
cellization enthalpy DHmic from titration curves. 204.5 mL of
demineralised and degassed water was titrated at 258C with
degassed phosphane solution in a 40 mL syringe. Concentra-
tions of phosphane were approximately 10 times higher than
the expected CMC. Aliquots of 1.1 mL of phosphane solu-
tion were delivered over 2 s and the corresponding heat
flow was recorded as a function of time. The time interval
between two consecutive injections was 150 s and agitation
speed was 1000 rpm for all experiments. The area under the
peak following each injection of the phosphane solution (ob-
tained by integration of the raw signal) is then expressed as
the heat effect per mole of added phosphane. Data analysis
was carried out using Microcal ORIGIN 7 software. Each ti-
tration was performed three times to ensure reproducibility
of the results. The reported CMC values are the meanÆ
standard deviation of the three experiments.
Cryo-TEM
1H NMR (300 MHz, D2O, 25 8C): d=6.96–7.10 (m, 13H,
Sample preparation: Specimens for cryo-TEM observation
were prepared using a cryoplunge cryo-fixation device
(Gatan, USA) in which a drop of the aqueous suspension
was deposited on to glow-discharged holey-type carbon-
coated grids (Ted Pella Inc., USA). The phosphane concen-
tration was 4 mM. The TEM grid was then prepared by blot-
ting the drop containing the specimen to a thin liquid layer
remained across the holes in the support carbon film. The
liquid film was vitrified by rapidly plunging the grid into
liquid ethane cooled by liquid nitrogen. The vitrified speci-
mens were mounted in a Gatan 910 specimen holder
(Gatan, USA) that was inserted in the microscope using a
CT-3500-cryotransfer system (Gatan, USA) and cooled with
liquid nitrogen. TEM images were then obtained from speci-
mens preserved in vitreous ice and suspended across a hole
in the supporting carbon substrate.
3
H-1, H-2, H-3, H-6, H-7), 7.09 (d, JH,H =8.0 Hz, 4H, H-10),
3
7.51 (d, JH,H =8.0 Hz, 4H, H-11); 13C{1H} NMR (75.5 MHz,
D2O, 25 8C): d=125.84 (s, C-11), 126.77 (s, C-10), 126.78
2
(broad d, C-7), 128.82 (broad d, C-1, C-2), 133.77 (d, JP, C
=
13.7 Hz, C-3, C-6), 136.57 (broad d, C-4, C-5), 139.35 (s, C-
8), 141.49 (s, C-9), 141.91 (s, C-12); 31P{1H} NMR
(121.5 MHz, D2O, 25 8C): d=À7.70 (s). MS (MALDI-TOF):
m/z=575.02 [PÀ2Na+3H]+, 597.02 [PÀNa+2H]+, 619.03
[P+H]+, 641.13 [P+Na]+, 1259.19 [2P+Na]+.
Surface Tension Measurements
The processor tensiometer Sigma 70 (KSV) and the Wilhel-
my plate method for air-water interface have been used for
the surface tension measurements at 258C. The precision of
the force transducer of the surface tension apparatus was
0.1 mN/m and, before each measurement, the platinum
plate was cleaned in a red/orange coloured flame. A concen-
trated solution of phosphane was installed in a syringe and
the addition of small volumes to ultrapure water enhanced
the solution concentration. After addition, the solution was
Microscopy: The samples were observed under low dose
conditions (<10 eÀ/A2), at À1788C, using a JEM 1230
ꢄCryoꢅ microscope (Jeol, Japan) operated at 80 kV and
equipped with a LaB6 filament. All the micrographs were
recorded on a Gatan 1.35 Kꢃ1.04 Kꢃ12 bit ES500W CCD
camera.
Adv. Synth. Catal. 2010, 352, 1193 – 1203
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1201

Michel Ferreira et al.
FULL PAPERS
Image analysis: The software ImageJ has been systemati-
cally used for enhancing the contrast and for image analysis
in order to get the particle size distributions from 5 cryo-
TEM micrographs (see Supporting Information).[14]
1995, 128, 275–279; g) T. Bartik, B. E. Hanson, J. Mol.
Catal. A: Chem. 1995, 98, 117–122; h) A. Andriollo, J.
Carrasquel, J. MariÇo, F. A. Lꢆpez, D. E. Pꢇez, I.
Rojas, N. Valencia, J. Mol. Catal. A: Chem. 1997, 116,
157–165; i) H. Ding, J. Kang, B. E. Hanson, C. W.
Kohlpaintner, J. Mol. Catal. A: Chem. 1997, 124, 21–
28; j) R. Chen, X. Liu, Z. Jin, J. Organomet. Chem.
1998, 571, 201–204; k) B. E. Hanson, H. Ding, C. W.
Kohlpaintner, Catal. Today 1998, 42, 421–429; l) J.
Jiang, Y. Wang, C. Liu, F. Han, Z. Jin, J. Mol. Catal. A:
Chem. 1999, 147, 131–136; m) E. Valls, J. Suades, R.
Suades, Organometallics 1999, 18, 5475–5483; n) S. Bis-
choff, M. Kant, Ind. Eng. Chem. Res. 2000, 39, 4908–
4913; o) S. Bischoff, A. Kçckritz, M. Kant, Top. Catal.
2000, 13, 327–334; p) M. S. Goedheijt, B. E. Hanson,
J. N. H. Reek, P. C. J Kamer, P. W. N. M. van Leeuwen,
J. Am. Chem. Soc. 2000, 122, 1650–1657; q) S. Bischoff,
M. Kant, Catal. Today 2001, 66, 183–189; r) L. Caron,
M. Canipelle, S. Tilloy, H. Bricout, E. Monflier, Tetra-
hedron Lett. 2001, 42, 8837–8840; s) X. Ma, X. Fu, J.
Mol. Catal. A: Chem. 2003, 195, 47–53; t) E. Paetzold,
G. Oehme, C. Fischer, M. Frank, J. Mol. Catal. A:
Chem. 2003, 200, 95–103; u) Q. Peng, Y. Yang, C.
Wang, X. Liao, Y. Yuan, Catal. Lett. 2003, 88, 219–225;
v) A. Solsona, J. Suades, R. Mathieu, J. Organomet.
Chem. 2003, 669, 172–181; w) Q. Peng, X. Liao, Y.
Yuan, Catal. Commun. 2004, 5, 447–451; x) M. Karls-
son, A. Ionescu, C. Andersson, J. Mol. Catal. A: Chem.
2006, 259, 231–237; y) S. Tilloy, E. Genin, F. Hapiot, D.
Landy, S. Fourmentin, J. P. GenÞt, V. Michelet, E. Mon-
flier, Adv. Synth. Catal. 2006, 348, 1547–1552; z) H. Fu,
M. Li, J. Chen, R. Zhang, W. Jiang, M. Yuan, H. Chen,
X. Li, J. Mol. Catal. A: Chem. 2008, 292, 21–27.
Catalytic Experiments
PdACHTUNGTRENNUNG(OAc)2 (4.5 mmol, 1 mg) and phosphane (40 mmol) were
introduced under a nitrogen atmosphere into a Schlenk tube
containing water (4 g). After stirring with a magnetic bar for
16 h, the yellow solution was transferred into a mixture of
butyl or allyl undecyl carbonate (450 mmol), diethylamine
(900 mmol), heptane (4 g) and dodecane (200 mmol) as inter-
nal standard. The medium was stirred at 1250 rpm at room
temperature and the reaction was monitored by quantitative
gas chromatographic analysis of the organic layer.
The phosphane concentration was equal to 10 mM but it
was considered that only five equivalents (ꢀ5.5 mM) from
the nine of phosphane (relative to Pd) are available in solu-
tion and can form aggregates. In fact, three equivalents were
used to stabilize the palladium(0) species Pd(phosphane)3
and one equivalent of phosphane was oxidized during reduc-
tion of the PdACHTUNGTRENNUNG(OAc)2 according to the following equation.
Acknowledgements
This work was supported by the Centre National de la Re-
cherche Scientifique (CNRS). M. Ferreira is grateful to the
Ministꢀre de l’Education et de la Recherche for financial sup-
port (2005–2008). The authors are grateful to CAPA (Centre
d’Analyse Protꢁomique de l’Artois) for mass spectrometry
analysis. The mass spectrometry facility used for this study
was funded by the European Community (FEDER), the
Fonds d’Industrialisation du Bassin Minier (FIBM), the Min-
istꢀre de l’Education Nationale, de l’Enseignement Supꢁrieur
et de la Recherche and the Universitꢁ d’Artois. The 500 MHz
NMR facilities were funded by the Rꢁgion Nord-Pas de
Calais (France), the Ministꢀre de la Jeunesse, de l’Education
Nationale et de la Recherche (MJENR) and the Fonds Eu-
ropꢁens de Dꢁveloppement Rꢁgional (FEDER).
[4] M. Ferreira, H. Bricout, F. Hapiot, A. Sayede, S. Tilloy,
E. Monflier, ChemSusChem 2008, 1, 631–636.
[5] M. Ferreira, H. Bricout, A. Sayede, A. Ponchel, S.
Fourmentin, S. Tilloy, E. Monflier, Adv. Synth. Catal.
2008, 350, 609–618.
1
[6] For examples of the use of JP,Se coupling constants to
determine phosphane basicity, see: E. Genin, R. Amen-
gual, V. Michelet, M. Savignac, A. Jutand, L. Neuville,
J. P. GenÞt, Adv. Synth. Catal. 2004, 346, 1733, and ref-
erences cited therein.
[7] K. Bouchemal, F. Agnely, A. Koffi, G. Ponchel, J. Col-
loid Interface Sci. 2009, 338, 169–176.
[8] Y. Cohen, L. Avram, L. Frish, Angew. Chem. 2005, 117,
524–560; Angew. Chem. Int. Ed. 2005, 44, 520–554.
[9] D. G. Regan, B. E. Chapman, P. W. Kuchel Magn.
Reson. Chem. 2002; 40: S115–S121.
[10] J. Harris, M. Adrian, in: Electron Microscopy Methods
and Protocols, Methods in Molecular Biology Series,
Vol. 117, (Ed. M. A. N. Hajibagheri), Humana press,
Totowa, NJ, 1999, pp 31–48.
References
[1] B. Cornils, W. A. Herrmann, in: Aqueous-Phase Organ-
ometallic Catalysis, (Eds.: B. Cornils, W. A. Herrmann),
Wiley-VCH, 2004, pp 3–16.
[11] Supplementary data are available in the Supporting In-
formation. Other cryoTEM images of phosphanes 2
and 4 and TEM images (negative staining) of phos-
phane 2 are presented. Interestingly, the average parti-
cle size of phosphane 2 determined from negative
staining TEM data was equal to 8.8Æ4.8 nm which is
close to the value obtained from cryoTEM data.
[12] a) S. Lemaire-Audoire, M. Savignac, E. Blart, G. Pour-
celot, J. P. GenÞt, J. M. Bernard, Tetrahedron Lett.
[2] K. H. Shaughnessy, Chem. Rev. 2009, 109, 643–710.
[3] a) A. F. Borowski, D. J. Cole-Hamilton, G. Wilkinson,
Nouv. J. Chim. 1978, 2, 137–144; b) B. Fell, G. Papado-
gianakis, J. Mol. Catal. 1991, 66, 143–154; c) T. Bartik,
B. Bartik, B. E. Hanson, J. Mol. Catal. 1994, 88, 43–56;
d) H. Ding, B. E. Hanson, J. Chem. Soc. Chem.
Commun. 1994, 2747–2748; e) H. Ding, B. E. Hanson,
T. Bartik, B. Bartik, Organometallics 1994, 13, 3761–
3763; f) F. Bitterer, S. Kucken, O. Stelzer, Chem. Ber.
1202
asc.wiley-vch.de
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2010, 352, 1193 – 1203

Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes
1994, 35, 8783–8786; b) J. P. GenÞt, E. Blart, M. Savi-
gnac, S. Lemeune, S. Lemaire-Audoire, J. M. Paris,
J. M. Bernard, Tetrahedron 1994, 50, 497–503; c) S.
Lemaire-Audoire, M. Savignac, G. Pourcelot, J. P.
GenÞt, J. M. Bernard, J. Mol. Catal. A. Chem. 1997,
116, 247–258; d) J. P. GenÞt, M. Savignac, J. Organo-
met. Chem. 1999, 576, 305–317.
[13] C. Binkowski, J. Cabou, H. Bricout, F. Hapiot, E. Mon-
flier, J. Mol. Catal. A: Chem. 2004, 215, 23–32.
[14] Research Services Branch NIMH & NINDS. ImageJ –
Image processing and analysis in Java. Web site: http://
rsb.info.nih.gov/ij.
Adv. Synth. Catal. 2010, 352, 1193 – 1203
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1203