Dendritic polyallyl and polyferrocenyl bipyridine ligands: Synthesis, MALDI-TOF characterization and ruthenium(II) complexation studies

Article abstract of DOI:10.1016/j.jorganchem.2008.11.036

A series of 6- and 18-armed dendritic polyallyl- and polyferrocenyl-containing bipyridine ligands were synthesized through the coupling reaction of 4,4′-bis(bromomethyl)-2,2′-bipyridine with AB₃ and AB₉ dendrons. All these bipyridine

Full text of DOI:10.1016/j.jorganchem.2008.11.036

Journal of Organometallic Chemistry 694 (2009) 637–642
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Dendritic polyallyl and polyferrocenyl bipyridine ligands: Synthesis,
MALDI-TOF characterization and ruthenium(II) complexation studies
*
Claire Jahier, Sylvain Nlate
Université de Bordeaux, Nanosciences and Catalysis Group, ISM, UMR CNRS No. 5255, 351 Cours de la Libération, 33405 Talence Cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 October 2008
Received in revised form 7 November 2008
Accepted 14 November 2008
Available online 27 November 2008
A series of 6- and 18-armed dendritic polyallyl- and polyferrocenyl-containing bipyridine ligands were
synthesized through the coupling reaction of 4,40-bis(bromomethyl)-2,20-bipyridine with AB3 and AB9
dendrons. All these bipyridine ligands were successfully characterized using standard physico-chemical
techniques as well as MALDI-TOF mass spectrometric analysis. The complexation studies of these
ligands toward RuCl2(bpy)2 indicated that, in contrast to the bulky 18-ferrocenyl bipyridine ligand 7,
the 6-allyl 4 and the 18-allyl 5 bipyridine ligands react with Ru(bpy)2Cl2 to give the corresponding
ruthenium(II) complexes 9 and 10. In the case of ligand 7, the steric bulk of the two nonaferrocenyl
wedges at the 4,40-position of the bipyridine moiety prevents the conversion of the transoid structure
of the ligand to the cisiod structure needed for chelation to the metal. Thus, the 18-ferrocenyl ruthe-
nium(II) dendrimer was not obtained. Metallodendrimers 9 and 10 have been characterized by a com-
bination of analytical methods, especially MALDI-TOF mass spectrometric techniques. The
hydrogenation of the 6-allyl ruthenium(II) dendrimer 9 in the presence of Pd/C catalyst gave the
expected n-propyl complex 11. This reaction constitutes a new way for the direct synthesis of alkyl
bipyridine metallodendrimers. The coordination of the alkene dendritic bipyridine ligand to the metal
before the catalytic hydrogenation is absolutely necessary, because of their poisoning effect for the
catalyst.
Keywords:
Allyl-bipyridine-ligands
Dendrimers
Ferrocenyl-bipyridine-ligands
Hydrogenation
Ruthenium(II) metallodendrimers
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
such as 2,20-bipyridine to ruthenium(II) have also proven effective-
ness in catalysis [13]. For example, Bruneau et al. have reported the
Construction of organic, inorganic and organometallic dendri-
mers is now a well-established field of research [1]. However, pub-
lications from the last few years demonstrate a continuing interest
in the development of new and ever more efficient synthetic meth-
odologies [2], and a considerable number of dendritic compounds
have been prepared for industrial applications [3] as well as aca-
demic studies [4]. Because of their controlled molecular architec-
tures, dendrimers have found use in various areas such as
catalysis [5], supramolecular chemistry [6], biomimetics [7], sur-
face chemistry [8], light-harvesting materials [9], and medicine
[10]. Among metallodendrimers, ruthenium bipyridine complexes
have been widely studied because of their versatile photo [11] -
and/or electrochemical [12] properties. It has been demonstrated
that the modification of dendritic ligands around the ruthenium(II)
affects the photochemical and electrochemical properties of the
metal [11,12]. Furthermore, chelating bidentate N-donor ligands
efficiency of ruthenium mono(bipyridine) complexes such as
[Cp*( 2-bipy)(CH3CN)Ru(II)][PF6], for the catalytic regioselective
g
nucleophilic substitution of unsymmetrical allylic carbonate
[11a]. In their investigations, they found that the catalytic proper-
ties in this reaction was dependent on the 2,20-bipyridine struc-
ture. Thus, introducing dendritic bipyridine ligands in such
systems should improve the stability, solubility, efficiency and
recyclability of the catalyst [14]. For the above mentioned reasons
and a variety of dendrimers and metallodendrimers application
domains, the design of new organic, inorganic and organometallic
dendritic structures [14,15] is highly desired. In this context, we
have synthesized and characterized new 2,20-bipyridine ligands
carrying AB3 or AB9 polyallyl- and polyferrocenyl dendritic wedge
in their 4,40-positions. We also describe the synthesis of two ruthe-
nium(II)-cored metallodendrimers bearing, respectively, 6- and
18-allyl groups at their periphery, as well as their MALDI-TOF mass
spectrometric analysis. Furthermore, we have shown that in
contrast to free allyl bipyridine ligands that are poison for the
Pd/C catalyst, the corresponding ruthenium(II) complexes were
hydrogenated in similar conditions, leading quantitatively to the
n-propyl counterparts.
* Corresponding author. Fax: +33 540 00 69 94.
E-mail address: s.nlate@ism.u-bordeaux1.fr (S. Nlate).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.11.036

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C. Jahier, S. Nlate / Journal of Organometallic Chemistry 694 (2009) 637–642
2.1.2. Synthesis of 18-ferrocenyl dendritic bipyridine ligand 7
2. Results and discussion
The synthetic procedure to the 18-ferrocenyl bipyridine ligand
7 is summarized in Scheme 2.
2.1. Synthesis and spectroscopic characterization of the 6- and 18-
armed dendritic bipyridine ligands
The coupling reaction of 4,40-bis(bromomethyl)-2,20-bipyridine
1 [17] with excess of nonaferrocenyl dendron 6 [18] in a mixture
of CH3CN and THF (1/1) gave, after purification on a silica gel col-
umn, the 18-ferrocenyl bipyridine ligand 7 as an orange solid in a
89% yield. The characterization of compound 7 was carried out
using standard NMR and MALDI-TOF mass spectrometric tech-
niques, as well as elemental analysis. Their MALDI-TOF mass spec-
trum contains a dominant molecular peak at m/z: 6846.32 [M]+,
and small amount of extra peaks probably due to fragmentation
in the mass spectrometer and traces of impurities left after the sil-
ica gel column. The proton NMR spectra of 7 exhibits three sets of
signals in the aromatic part at 8.68, 8.51 and 7.46 ppm, assigned to
the three protons of the bipyridine moiety. The 18-ferrocenyl
bipyridine 7 represent an interesting polymetallic ligand for the
direct synthesis of hetero polymetallodendrimers having new
photo-, electrochemical and catalytic properties.
2.1.1. Synthesis of 6- and 18-allyl dendritic bipyridine
compounds 4 and 5
Dendritic polyallyl bipyridine ligands 4 and 5 were synthesized
as summarized in Scheme 1, following the literature procedure
[11a].
The excess of 3-allyl phenol dendron 2 [15b,16] and the 9-allyl
phenol dendrons 3 [16] react with 4,40-bis(bromomethyl)-2,20-
bipyridine 1 [17] to give the corresponding dendritic 6-allyl and
18-allyl bipyridine ligands 4 and 5 in 96% and 95% yield, respec-
tively. In this step, the number of peripheral functions is doubled.
The reaction was followed by the complete disappearance of the
1H NMR signal at 4.50 ppm, assigned to the CH2Br group, and
the appearance of a singlet at 5.17 ppm indicative of the CH2O
bond formation. Dendritic bipyridine ligands 4 and 5 were suc-
cessfully characterized by standard NMR and mass spectrometric
analysis. Prominent molecular peaks at m/z: 637.48 [M]+ for 4
and m/z: 2006.38 [M]+ for 5 are present in their mass spectrum.
The aromatic region of 4 and 5 in their 1H NMR spectra exhibits
2.2. Synthesis and characterization of 6- and 18-allyl dendritic
bipyridine ruthenium(II) complexes 9 and 10
The complexation of dendritic bipyridine ligands 4 and 5 with
RuCl2(bpy)2 complex 8 [17] gave the 6-allyl and 18-allyl dendritic
three sets of signals (a doublet at 8.69 ppm,
a singlet at
8.46 ppm and a doublet at 7.45 ppm for 4, and a doublet at
8.69 ppm, a singlet at 8.48 ppm and a doublet at 7.46 ppm for 5)
assigned to the three different aromatic protons of bipyridine moi-
eties. Attempts to prepare the n-propyl counterparts of 4 and 5 by
catalytic hydrogenation of allyl groups, using Pd/C catalyst were
unsuccessful. Indeed, free bipyridine ligands are poison for the
Pd/C catalyst, they inhibit its activity. Thus, the access to n-propyl
bipyridine derivatives is not possible using these reaction
conditions.
bipyridine ruthenium(II) complexes
(Scheme 3).
9 and 10, respectively
The reaction of the readily obtained RuCl2(bpy)2 complex 8 [17]
with, respectively, one equivalent of 6-allyl-2,20-bipyridine ligand
4 or 18-allyl-2,20-bipyridine ligand 5 in boiling ethanol for three
days, gave the hexafluorophosphate salts of 6-allyl-2,20-bipyridine
ruthenium complex 9 and 18-allyl-2,20-bipyridine ruthenium com-
plex 10 in 89 and 92% yield. Compounds 9 and 10 were obtained as
Br
N
N
Br
O
1
N
HO
N
CH3CN
O
80 ˚C, 24h,
85%
2
4
O
O
Br
N
N
O
O
Br
O
1
N
O
HO
N
CH3CN
O
O
80 °C, 24h,
O
90%
5
O
3
O
Scheme 1. Synthesis of the 6- and 18-allyl dendritic bipyridine ligands 4 and 5.

C. Jahier, S. Nlate / Journal of Organometallic Chemistry 694 (2009) 637–642
639
Fe
Si
Fe
Fe
Si
Fe
Si
Si
Fe
Si
Si
Fe
Fe
Fe
Si
Fe
O
Br
Br
O
Si
Si
N
N
Fe
Si
O
Fe
Si
Fe
Si
O
O
O
Fe
1
N
N
HO
O
Fe
Si
Fe
CH3CN/THF
80 °C, 24h
89%
O
Si
Si
Fe
Fe
O
Si
6
Si
Fe
Si
Si
O
Fe
Si
O
Fe
Si
7
Fe
Fe
Si
Fe
Si
Si
Fe
Si
Fe
Fe
Si
Fe
Scheme 2. Synthesis of the 18-ferrocenyl dendritic bipyridine ligand 7.
-
2 PF4
2+
N
Ru
N
O
O
N
N
N
O
8
N
N
N
Ethanol reflux, 72h
NH4PF6
O
89%
4
9
O
-
O
2 PF4
2+
O
O
O
O
N
O
N
N
O
8
N
N
N
N
Ru
Ethanol reflux, 72h
NH4PF6
O
N
O
O
O
92%
O
O
10
O
5
O
8 : Ru(Bipy)2Cl2
Scheme 3. Synthesis of dendritic allyl bipyridine ruthenium(II) complexes 9 and 10.
yellow-orange solids. Due to the presence of allyl dendritic wedge
in their structures, they are soluble in common halogenated hydro-
carbons solvent such as CDCl3 or CD2Cl2. The structure of the den-
dritic complexes 9 and 10 were readily identified by their NMR
spectra and MALDI-TOF mass spectrometry. The MALDI-TOF mass
spectrum of each complex shows two prominent peaks at m/z:
1195.15 (calcd.: 1195.28) and 1050.21 (calcd.: 1050.32) for 9 and
2565.88 (calcd.: 2565.29) and 2418.49 (calcd.: 2420.32) for 10, as-
signed, respectively, to [MꢀPF6]+ and [Mꢀ2PF6]+. The investiga-
tions of photo- and electrochemical behaviors of these
metallodendrimers as well as the use of the above mentioned den-
dritic ligands in catalysis are currently underway. In contrast to al-
lyl bipyridine ligands 4 and 5, the complexation of RuCl2(bpy)2
with the 18-ferrocenyl bipyridine ligand
7 did not proceed

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C. Jahier, S. Nlate / Journal of Organometallic Chemistry 694 (2009) 637–642
-
2+ 2 PF4
N
O
O
O
8
N
N
N
N
N
N
Ru
N
Ethanol reflux, 72h
NH4PF6
O
89%
9
4
cat. Pd/C
RT, 6h
89%
cat. Pd/C
RT, 6h
-
2+
2 PF4
N
O
O
8
N
N
N
N
N
Ru
N
N
NH4PF6
O
O
4a
11
8 :
Ru(Bipy)2Cl2
Scheme 4. Synthesis of the 6-n-propyl dendritic bipyridine ruthenium(II) complex 11.
smoothly under the same experimental conditions. The expected
ruthenium(II) complex was not obtained and the bipyridine nonaf-
errocenyl ligand 7 was quantitatively recovered. Lengthening the
reaction time under hard reaction conditions (reflux of DMF) was
also unsuccessful. This result is probably due to the conversion of
the transoid structure of the free ligand to the cisoid conformation
(needed for metal chelation), prevented from the steric bulk of the
two nonaferrocenyl wedges at the 4,40-positions of the bipyridine
moiety.
dine ligands were successfully characterized by their molecular
peak in MALDI-TOF mass spectrometric analysis. Except for the
18-ferrocenyl compound, the complexation of these ligands to
Ru(bpy)2Cl2 was also successful. The corresponding metallodendri-
mers were obtained and identified by their molecular peak in MAL-
DI-TOF mass spectrometry. In the case of the 18-ferrocenyl ligand,
the steric bulk of the two dendritic wedge at the 4,40-positions of
the bipyridine moiety prevents the transoid free ligand to isomer-
ize to the cisoid form, an essential feature for their chelation to the
metal. Furthermore, we have also shown that the complexation of
allyl bipyridine ligands to the metal follow by hydrogenation of al-
lyl groups is a valuable procedure for the synthesis of various poly-
alkyl bipyridine-based complexes. We are currently investigating
the photochemical and electrochemical properties of these ligands
and metallodendrimers. We are also studied their complexation
behavior as well as their influences on the properties of catalyti-
cally active species.
2.3. Synthesis of 6-n-propyl dendritic bipyridine ruthenium(II)
complexex 11
Pursuing our investigation in the preparation of new organic
and organometallic dendrimers, we have successfully synthesized
the 6-n-propyl dendritic bipyridine ruthenium(II) complex 11 from
their 6-allyl counterpart 9, by hydrogenation using Pd/C catalyst
(10% Pd) as summarized in Scheme 4.
Whereas allyl bipyridine ligands 4 and 5 are inert towards
hydrogen in the presence of Pd/C catalyst, their complexation to
the ruthenium(II) before the hydrogenation of allyl groups repre-
sents a direct and quantitative procedure for the synthesis of
n-polypropyl ruthenium(II) complexes. Thus the complexation of
6-propyl bipyridine ligand 4 to RuCl2(bpy)2 8 followed by the
hydrogenation of allyl groups led to the 6-n-propyl complex 11.
The NMR data of 11 as well as their MALDI-TOF mass spectrum
are consistent with the proposed structure. The MALDI-TOF mass
4. Experimental
4.1. General remarks
Reagent-grade tetrahydrofuran (THF), diethyl ether, and pen-
tane were pre-dried over Na foil and distilled from sodium-benzo-
phenone anion under argon immediately prior to use. Acetonitrile
(CH3CN) was stirred under argon overnight over phosphorus pent-
oxide, distilled from sodium carbonate, and stored under argon.
Methylene chloride (CH2Cl2) was distilled from calcium hydride
just before use. All other chemicals were used as received. The
1H, 13C, 31P NMR spectra were recorded at 25 °C with a Brucker
AC 250 FT spectrometer (1H: 250.13, 13C: 62.91 MHz) and a Bruc-
ker AC 200 FT spectrometer (1H: 200.16, 13C: 50.33, 31P: 81.02,
19F: 188.33 MHz) at the CESAMO. All chemical shifts are reported
in parts per million (d, ppm) with reference to Me4Si (TMS). Ele-
mental analyses were carried out at the Vernaison CNRS center.
The matrix-assisted laser-desorption (MALDI) mass spectra were
recorded using a Perceptive Biosystems Voyager Elite (Framing-
ham, MA) time-of-flight (TOF) mass spectrometer.
spectrum shows
a prominent peak at m/z: 1209.49 (calcd.:
1209.39) assigned to [MꢀPF6]+. The complexation of the bipyridine
moiety to ruthenium(II) is an essential step for the preparation of
11, because its avoids the free ligands poisoning of the Pd/C cata-
lyst, that inhibits the hydrogenation reaction in these conditions.
3. Conclusion
In this paper, we are reporting the synthesis and characteriza-
tion of dendritic 2,20-bipyridine ligands bearing bearing 3-allyl
and 9-allyl as well as 9-ferrocenyl dendritic wedge at their 4,40-
positions. The obtained 6-allyl, 18-allyl and 18-ferrocenyl bipyri-

C. Jahier, S. Nlate / Journal of Organometallic Chemistry 694 (2009) 637–642
641
4.2. General procedure for the synthesis of dendritic bipyridine ligands
4.3. General procedure for the synthesis of dendritic bipyridine
ruthenium(II) (9) and (10)
4.2.1. Dendritic 6- and 18-allyl bipyridine ligands (4) and (5)
One equivalent of 4,40-bis(bromomethyl)-2,20-bipyridine (1)
was treated with two equivalents of dendron in the presence of
three equivalents of K2CO3 in CH3CN. The mixture was stirred at re-
flux for 24 h. After removal of the solvent under vacuum, the prod-
uct was extracted with Et2O and dried over Na2SO4. The solvent
was evaporated and the product was purified by chromatography
(silica gel, pentane/diethyl ether 8:2; then diethyl ether).
One equivalent of Ru(bpy)2Cl2 was added to a solution of one
equivalent of dendritic 2,20-bipyridine ligand in ethanol. The mix-
ture was stirred at reflux for 3 days. After removal of the solvent
under vacuum, the residue was dissolved in CH2Cl2 and the solu-
tion washed with water several times. The solvent was removed
under vacuum and the residue dissolved in a mixture of acetone
and water (v/v 2:1). After addition of NH4PF6, an orange-yellow so-
lid was formed. The later was dissolved in CH2Cl2, the organic layer
was washed with water and dried over Na2SO4. The solvent was re-
moved under vacuum to yield the bipyridine complexes as orange-
yellow solids.
4.2.1.1. Dendritic 6-allyl bipyridine ligand (4). This compound was
obtained as a white solid in 85% yield. 1H NMR (CDCl3, 250 MHz)
3
dppm: 8.69 (d, JH,H = 5 Hz, 2H, pyridine-H), 8.46 (s, 2H, pyridine-
3
3
H), 7.45 (d, JH,H = 5 Hz, 2H, pyridine-H), 7.23 (d, JH,H = 8.3 Hz,
3
4.3.1. Dendritic 6-allyl bipyridine complex (9)
4H, Ar), 6.94 (d, JH,H = 8.7 Hz, 4H, Ar), 5.57 (m, 6H, CH2CH@CH2),
This compound was obtained in 89% yield. 1H NMR (CDCl3,
250 MHz) dppm: 8.55 (s, 2H, pyridine-H), 8.40 (dbroad, 4H, pyri-
dine-H), 7.95 (t, 4H, pyridine-H), 7.77 (t, 4H, pyridine-H), 7.71 (d,
2H, pyridine-H), 7.54 (dbroad, 2H, pyridine-H), 7.42 (tbroad, 4H, pyri-
5.16 (s, 4H, CH2O), 4.96 (m, 12H, CH2CH@CH2), 2.42 (d,
3JH,H = 7.1 Hz, 12H, CH2CH@CH2). 13C NMR (CDCl3, 63 MHz) dppm
:
156.2 (Cq, Ar–O), 156.1 (Cq, Ar–O), 156.0 (C, Ar-pyridine), 153.2
(Cq, Ar), 149.5 (C, Ar-pyridine), 147.6 (Cq, Ar), 139.1 (C, Ar-pyri-
dine), 134.6 (CH2CH@CH2), 127.8 (CH, Ar), 121.8 (C, Ar-pyridine),
119.1 (C, Ar-pyridine), 117.6 (CH2CH@CH2), 114.3 (CH, Ar), 68.4
(CH2-O), 42.5 (C-CH2), 42.8 (C-CH2), 41.9 (CH2). MS (EI, 70 eV) m/
z: 637.43 [M]+ (calcd. 638.87). Elemental Anal. Calc. for
C44H48O2N2 (638.87): C, 82.98; H, 7.60. Found: C, 83.62; H, 7.62%.
3
3
dine-H), 7.24 (d, JH,H = 8.3 Hz, 4H, Ar), 6.96 (d, JH,H = 8.7 Hz, 4H,
Ar), 5.53 (m, 6H, CH2CH@CH2), 5.24 (s, 4H, CH2O), 4.98 (m, 12H,
CH2CH@CH2), 2.42 (d, JH,H = 7.1 Hz, 12H, CH2CH@CH2). 13C NMR
3
(CDCl3, 63 MHz) dppm: 156.4 (Cq, Ar–O), 155.4 (C, Ar-pyridine),
151.4 (Cq, Ar), (C, Ar-pyridine), 151.0 (C, Ar-pyridine), 149.7 (C,
Ar-pyridine), 149.6 (Cq, Ar), 139.3 (C, Ar-pyridine), 137.9 (C, Ar-pyr-
idine), 134.4 (CH2CH@CH2), 128.0 (CH, Ar), 126.0 (C, Ar-pyridine),
124.2 (C, Ar-pyridine), 122.1 (C, Ar-pyridine), 119.1 (C, Ar-pyridine),
117.6 (CH2CH@CH2), 114.3 (CH, Ar), 67.4 (CH2-O), 43.0 (C-CH2),
41.8 (CH2). 31P NMR (CDCl3, 50.33 MHz) dppm: 59.8 (PF6). 19F NMR
(CDCl3, 188.33 MHz) dppm: ꢀ72.2 (PF6). MALDI-TOF mass spectrum,
m/z: 1195.15 [MꢀPF6]+ (calcd.: 1195.28) and 1050.21 [Mꢀ2PF6]+
(calcd.: 1050.32). Elemental Anal. Calc. for C64H64O2N6F12P2Ru
(1340.35): C, 57.35; H, 4.81. Found: C, 57.63; H, 4.66%.
4.2.1.2. Dendritic 18-allyl bipyridine ligand (5). This compound was
obtained as a white solid in 90% yield. 1H NMR (CDCl3, 250 MHz)
3
dppm: 8.70 (d, JH,H = 5 Hz, 2H, pyridine-H), 8.47 (s, 2H, pyridine-
3
3
H), 8.46 (d, JH,H = 5 Hz, 2H, pyridine-H), 7.31 (d, JH,H = 8.3 Hz,
3
3
4H, Ar), 7.19 (d, JH,H = 8.5 Hz, 12H, Ar), 6.95 (d, JH,H = 8.3 Hz, 4H,
3
Ar), 6.81 (d, JH,H = 8.5 Hz, 12H, Ar), 5.57 (m, 18H, CH2CH@CH2),
5.17 (s, 4H, CH2O), 4.96 (m, 36H, CH2CH@CH2), 3.89 (broad, 12H,
3
CH2O), 2.41 (d, JH,H = 6.9 Hz, 12H, CH2CH@CH2), 1.99 (broad,
12H, CH2), 1.60 (broad, 12H, CH2). 13C NMR (CDCl3, 63 MHz) dppm
:
4.3.2. Dendritic 18-allyl dendritic bipyridine complex (10)
This compound was obtained as a white solid in 92% yield. 1H
NMR (CDCl3, 250 MHz) dppm: 8.59 (s, 2H, pyridine-H), 8.36 (d,
156.7 (Cq, Ar–O), 156.1 (Cq, Ar–O), 156.0 (C, Ar-pyridine), 153.2 (Cq,
Ar), 149.4 (C, Ar-pyridine), 147.5 (Cq, Ar), 139.1 (C, Ar-pyridine),
138.3 (Cq, Ar), 137.4 (CH, Ar), 134.5 (CH2CH@CH2), 127.6 (CH,
Ar), 127.5 (CH, Ar), 121.6 (C, Ar-pyridine), 118.8 (C, Ar-pyridine),
117.4 (CH2CH@CH2), 113.7 (CH, Ar), 68.3 (CH2-O), 68.0 (CH2-O),
42.5 (C-CH2), 42.0 (C-CH2), 41.9 (CH2), 33.6 (CH2), 23.6 (CH2). MAL-
DI-TOF mass spectrum, m/z: 2006.4 [M]+ (calcd. 2006.8). Elemental
Anal. Calc. for C140H168O8N2: C, 83.78; H, 8.43. Found: C, 83.62; H,
8.47%.
3
3JH,H = 8.3 Hz, 4H, pyridine-H), 7.97 (t, JH,H = 8 Hz, 4H, pyridine-
H), 7.74 (m, 4+2H, pyridine-H), 7.50 (m, 4+2H, pyridine-H), 7.32
3
3
(d, JH,H = 8.8 Hz, 4H, Ar), 7.19 (d, JH,H = 8.5 Hz, 12H, Ar), 6.95 (d,
3JH,H = 8.3 Hz, 4H, Ar), 6.79 (d, JH,H = 8.5 Hz, 12H, Ar), 5.55 (m,
3
18H, CH2CH@CH2), 5.3 (s, 4H, CH2O), 4.99 (m, 36H, CH2CH@CH2),
3.90 (broad, 12H, CH2O), 2.41 (d, 12H, CH2CH@CH2), 1.86 (broad,
12H, CH2), 1.58 (broad, 12H, CH2). 13C NMR (CDCl3, 63 MHz) dppm
:
157.1 (Cq, Ar–O), 156.3 (Cq, Ar–O), 155.9 (C, Ar-pyridine), 149.1 (C,
Ar-pyridine), 147.5 (Cq, Ar), 139.3 (C, Ar-pyridine), 137.2 (Cq, Ar),
137.4 (CH, Ar), 134.6 (C, CH2CH@CH2), 127.6 (CH, Ar), 127.4 (CH,
Ar), 121.7 (C, Ar-pyridine), 118.5 (C, Ar-pyridine), 116.8
(CH2CH@CH2), 113.7 (CH, Ar), 67.9 (CH2-O), 67.8 (CH2-O), 42.3
(C-CH2), 41.8 (C-CH2), 41.6 (CH2), 33.4 (CH2), 23.5 (CH2); 31P
NMR (CDCl3, 50.33 MHz): d = 59.8 (PF6). 19F NMR (CDCl3,
188.33 MHz) dppm: ꢀ72.2 (PF6). MALDI-TOF mass spectrum, m/z:
2565.49 [MꢀPF6]+ (calcd. 2565.29), 2418.49 [Mꢀ2PF6]+ (calcd.
2420.32). Elemental Anal. Calc. for C160H184F12N6O8P2Ru: C,
70.91; H, 6.84. Found: C, 71.01; H, 6.80%.
4.2.2. Dendritic 18-ferrocenyl bipyridine ligand (7)
This compound was obtained as an orange solid in 89% yield,
according to the procedure described above for 4 and 5, but using
a mixture of CH3CN and THF (v/v 1:1) as solvent, instead of CH3CN.
1H NMR (CDCl3, 250 MHz) dppm: 8.67 (broad, 2H, pyridine-H), 8.48
(broad, 2H, pyridine-H), 7.46 (broad, 2H, pyridine-H), 7.32 (broad,
3
4H, Ar), 7.15 (d, JH,H = 8.5 Hz, 12H, Ar), 6.92 (broad, 4H, Ar), 6.85
3
(d, JH,H = 7.5 Hz, 12H, Ar), 5.15 (s, 4H, CH2O), 4.29 (s, 36H, Cp),
4.08 (s, 90H, Cp), 4.01 (s, 36H, Cp), 3.51 (s, 12H, CH2O), 1.60 (broad,
12H, CH2), 1.21 (broad, 12H, CH2), 0.62 (broad, 24H, CH2Si), 0.16
(broad, 108H, CH3Si), 0.08 (broad, 36H, CH3Si). 13C NMR (CDCl3,
63 MHz) dppm: 159.01 (Cq, Ar–O), 156.1 (Cq, Ar–O), 156.0 (C, Ar-
pyridine), 153.2 (Cq, Ar), 149.4 (C, Ar-pyridine), 139.7 (Cq, Ar),
139.1 (C, Ar-pyridine), 138.3 (Cq, Ar), 127.6 (CH, Ar), 127.2 (CH,
Ar), 121.6 (C, Ar-pyridine), 118.8 (C, Ar-pyridine), 113.7 (CH, Ar),
73.0 (C5H4), 71.4 (CH2-O), 70.6 (CH, C5H4), 68.1 (C5H5), 60.2 (CH2-
O), 43.2 (C-CH2), 42.2 (C-CH2), 18.2 (CH2), 17.6 (CH2Si), 14.5
(CH2), ꢀ1.8 (SiCH3), ꢀ4.5 (SiCH3). MALDI-TOF mass spectrum, m/
z: 6846.2 [M]+ (calcd. 6841.4). Elemental Anal. Calc. for
C374H510O8N2Si24Fe18: C, 65.66; H, 7.51. Found: C, 65.67; H, 7.54%.
4.3.3. 6-n-propyl dendritic bipyridine complex (11)
This compound was obtained as an orange-red oil in 89% yield.
1H NMR (CDCl3, 250 MHz) dppm: 8.52 (s, 2H, pyridine-H), 8.40 (d,
4H, pyridine-H), 7.97 (t, 4H, pyridine-H), 7.74 (t, 4H, pyridine-H),
7.68 (d, 2H, pyridine-H), 7.56 (d, 2H, pyridine-H), 7.46 (m, 4H, pyr-
3
3
idine-H), 7.24 (d, JH,H = 8.3 Hz, 4H, Ar), 6.92 (d, JH,H = 8.7 Hz, 4H,
Ar), 5.24 (s, 4H, CH2O), 1.56 (m, 12H, CH2), 1.03 (m, 12H, CH2),
0.84 (t, 18H, CH3). 13C NMR (CDCl3, 63 MHz) dppm: 156.5 (Cq, Ar–
O), 156.4 C, Ar-pyridine), 155.1 (C, Ar-pyridine), 151.5 (Cq, Ar),

642
C. Jahier, S. Nlate / Journal of Organometallic Chemistry 694 (2009) 637–642
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151.4 (C, Ar-pyridine), 151.0 (C, Ar-pyridine), 149.6 (C, Ar-pyri-
dine), 141.7 (C, Ar-pyridine), 137.9 (C, Ar-pyridine), 128.2 (C,
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42.7 (C-CH2), 40.2 (CH2), 16.7 (CH2), 14.8 (CH3). 31P NMR (CDCl3,
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:
ꢀ72.3 (d, PF6). MALDI-TOF mass spectrum, m/z: 1209.49 [MꢀPF6]+,
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The authors are grateful to Dr. J.-C. Blais for MALDI-TOF mass
spectrometric analyses. Financial support from the University of
Bordeaux, the CNRS, the ANR-06-BLAN-0215 (CJ), is also gratefully
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