Macrocyclic complexes of [Ru(N-N)2]2+ units [N-N = 1,10 phenanthroline or 4-(p-anisyl)-1,10-phenanthroline]: Synthesis and photochemical expulsion studies

Article abstract of DOI:10.1002/ejic.200390066

Two ruthenium complexes [Ru(phen)₂(m-36)]²⁺ and [Ru(aphen)₂(m-36)]²⁺, indicated as 1 and 2 respectively, which contain a 36-membered macrocycle incorporating a sterically hindered bipyridine (m-36), and two 1,10-phenanthroline (phen) or 4-(p-anisyl)-1,10-phenanthroline (aphen) ligands, have been synthesised. Under light irradiation, as seen from the metal-to-ligand-charge-transfer (MLCT) bands of the visible spectral region, the [Ru(phen)]₂²⁺ core of 1 and 2 is selectively expelled from the macrocycle to give the corresponding bis-acetonitrile derivative. This photochemical process was found to be notably less efficient than that observed in a simpler related complex [Ru(phen)₂dmbp]²⁺ (dmbp = 6,6′dimethyl-2,2′-bipyridine), that lacks the macrocyclic motif. In the case of 1 thermal back reaction takes place quantitatively affording a completely reversible system. The isolation, by chromatographic techniques, of the axial-axial cis-[(a,a)Ru(aphen)₂Cl₂] isomer, where the two aphen ligands bear two p-anisyl groups disposed trans to one another enabled the preparation of 2. This type of complex undergoes a more complicated photochemical process, in fact, following the expected photolabilisation of the [Ru(aphen)₂]²⁺ unit, photoisomerisation of the primary photo-product occurs and gives a statistical mixture of the three geometrical isomers: cis-[(a,a)Ru(aphen)₂(CH₃CN)₂] (PF₆)₂, cis-[(a,e)Ru(aphen)₂(CH₃CN)₂] (PF₆)₂ and cis-[(e,e)Ru(aphen)₂(CH₃CN)₂] (PF₆)₂. This side-reaction precludes its use as rotaxane precursor suggesting that, for this purpose, a bis-phenanthroline ligand stabilising the ruthenium core is needed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejic.200390066

FULL PAPER
Macrocyclic Complexes of [Ru(N-N)2]2؉ Units [N-N ؍ 1,10 Phenanthroline or
4-(p-Anisyl)-1,10-Phenanthroline]: Synthesis and Photochemical Expulsion Studies
Anne-Chantal Laemmel,[a] Jean-Paul Collin,*[a] Jean-Pierre Sauvage,*[a] Gianluca Accorsi,[b]
and Nicola Armaroli*[b]
Keywords: Ruthenium / Macrocycles / Receptors / Photochemistry / Molecular machines
Two ruthenium complexes [Ru(phen)2(m-36)]2+ and [Ru-
(aphen)2(m-36)]2+, indicated as 1 and 2 respectively, which
contain a 36-membered macrocycle incorporating a sterically
hindered bipyridine (m-36), and two 1,10-phenanthroline
isolation, by chromatographic techniques, of the axial-axial
cis-[(a,a)Ru(aphen)2Cl2] isomer, where the two aphen ligands
bear two p-anisyl groups disposed trans to one another en-
abled the preparation of 2. This type of complex undergoes
(phen) or 4-(p-anisyl)-1,10-phenanthroline (aphen) ligands, a more complicated photochemical process, in fact, following
have been synthesised. Under light irradiation, as seen from
the expected photolabilisation of the [Ru(aphen)2]2+ unit,
photoisomerisation of the primary photo-product occurs and
the metal-to-ligand-charge-transfer (MLCT) bands of the vis-
2+
ible spectral region, the [Ru(phen)]2 core of 1 and 2 is se- gives a statistical mixture of the three geometrical isomers:
lectively expelled from the macrocycle to give the corres- cis-[(a,a)Ru(aphen)2(CH3CN)2](PF6)2, cis-[(a,e)Ru(aphen)2-
ponding bis-acetonitrile derivative. This photochemical pro-
(CH3CN)2](PF6)2 and cis-[(e,e)Ru(aphen)2(CH3CN)2](PF6)2.
cess was found to be notably less efficient than that observed This side-reaction precludes its use as rotaxane precursor
in a simpler related complex [Ru(phen)2dmbp]2+ (dmbp =
6,6Јdimethyl-2,2Ј-bipyridine), that lacks the macrocyclic
motif. In the case of 1 thermal back reaction takes place
quantitatively affording a completely reversible system. The
suggesting that, for this purpose, a bis-phenanthroline ligand
stabilising the ruthenium core is needed.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
with a [Ru(phen)2]2ϩ core (phen ϭ 1,10-phenanthroline)
leads to the specific and quantitative photolabilisation of
the chelate.[7] Indeed, excitation into the absorption bands
of RuII-polyimine complexes corresponding to the singlet
metal-to-ligand-charge-transfer transitions (1MLCT) is fol-
lowed by intersystem crossing to the lowest-lying triplet
level (3MLCT) which, by thermal redistribution, may popu-
late upper-lying dissociative d-d metal centred (MC)
states.[8] The MC/MLCT energy gap is small and the ther-
mal deactivation of the 3MLCT state is particularly effective
when the ligand field is weakened by distortions due to the
sterically hindering ligands. A recent communication de-
scribed a system constituted by a [Ru(phen)2]2ϩ-type frag-
ment hosted in a macrocyclic receptor.[9] The present article
extends this previous example to a possible rotaxane pre-
cursor and evidences the limitations brought by a competit-
ive photoisomerisation reaction. Figure 1 displays the basis
of the photochemical expulsion of the ruthenium unit from
a macrocycle and its thermal back re-coordination.
The accessibility to rotaxanes and catenanes by strategies
based on various template effects allowed their involvement
in different research fields such as photo-induced energy
and electron transfer or molecular machines.[1] The pres-
ence of mechanical bonds, an intrinsic property of such spe-
cies, should confer good reversibility to systems designed
for specific tasks related to large amplitude movements. The
control of molecular motion for example is an essential
function in artificial[2] as well as in biological systems[3]
(ATPsynthase, myosin-actin, etc.).Very often, motions in
the molecules or molecular assemblies have been triggered
by chemical[4] or electrochemical signals.[5] Relatively few
systems rely on purely photonic input.[6] We now report on
a transition metal light-driven system based on dissociative
photoexcited states. RuII complexes of the [Ru(diimine)3]2ϩ
family (diimine ϭ bidentate ligand) seem to be promising in
building light-driven machines, since the use of a sterically
hindered chelate (e.g. a 6,6Ј substituted bipy) associated
Results and Discussion
[a]
´
Laboratoire de Chimie Organo-minerale, Institut Le Bel,
´
Universite Louis Pasteur,
The ruthenium complexes [Ru(phen)2(m-36)]2ϩ (1) and
[Ru(aphen)2(m-36)]2ϩ (2) [see a) in Figure 2] in which a bi-
pyridine unit is incorporated in a macrocycle have been syn-
thesised as possible rotaxane precursors. Indeed, the re-
4 rue Blaise Pascal, 67 070 Strasbourg, France
E-mail: sauvage@chimie.u-strasbg.fr
Istituto per la Sintesi Organica e la Fotoreattivita del CNR,
[b]
`
via Gobetti 101, 40129 Bologna, Italy
E-mail: armaroli@frae.bo.cnr.it
Eur. J. Inorg. Chem. 2003, 467Ϫ474  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0203Ϫ0467 $ 20.00ϩ.50/0
467

A.-C. Laemmel, J.-P. Collin, J.-P. Sauvage, G. Accorsi, N. Armaroli
FULL PAPER
Figure 1. Principle of the photochemically driven motion and the
thermal backward reaction
Scheme 1
Figure 2. (a) Chemical structures of complexes 1 and 2. (b) Possible
photochemical reaction leading to a rotaxane if bulky stoppers are
attached in the 4 positions
placement of the R group by bulky substituents and the
photosubstitution of the bipyridine-based macrocycle by
two molecules of solvent (CH3CN) could lead to a real rot-
axane as depicted in Figure 2, b). The synthesis of 1 and 2
is accomplished by applying the strategy of threading or
clipping.
In this latter strategy the complexation of an appropriate
bipyridine derivative bearing terminal olefins (3) precedes
the closure of the macrocycle (Scheme 1 and 2).
The 2,2Ј-bipyridine ligand 3 substituted at its 6 and 6Ј
positions by two long chains terminated by olefinic groups
was prepared in five steps from the 6,6Ј-dimethyl-2,2Ј-bi-
pyridine (dmbp).[10] By deprotonation of dmbp with LDA
in THF and reaction with two equivalents of THP-pro-
tected bromoethanol (THP ϭ tetrahydropyran-2-yl) 4 was
Scheme 2
obtained in 63% yield. Deprotection of 4 afforded 5 in 70% toluenesulfonic acid (pTsOH) in ethanol led to the corres-
yield. This alcohol was converted into 6 following the Willi- ponding diol 7 in good yield (84%). The conversion of 7 to
amson methodology (NaH/DME) by reaction with 2-{2-[2- ligand 3 bearing terminal olefins was achieved with a large
(2-chloroethoxy)ethoxy)]ethoxy}tetrahydro-2H-pyran (53% excess of allyl bromide in the presence of NaH in DME
yield). Deprotection with catalytic amounts of para- (75% yield).
468
Eur. J. Inorg. Chem. 2003, 467Ϫ474

Macrocyclic Complexes of [Ru(N-N)2]2ϩ Units
FULL PAPER
It was recently shown that cis-[Ru(phen)2(CH3CN)2]2ϩ is method is compatible with a large variety of functions and
a more efficient starting material than the classical bis- has also been proved to be well suited to the synthesis of
chloro derivative cis-[Ru(phen)2Cl2] for introducing a third catenanes and molecular knots.[17] By using a relatively high
chelate onto the ruthenium centre.[11] Good yields of 8 were concentration of the precursor complexes 8 and 9 (0.01 ,
obtained by heating a stoichiometric mixture of cis- CH2Cl2 solution) and 7% of the ruthenium complex [Ru]
[Ru(phen)2(CH3CN)2]2ϩ [12] and 3 in ethylene glycol at 140 (Scheme 2) as a catalyst the targeted complexes 1 and 2
°C for 2 h. After column chromatography and anion ex- were obtained in 67 and 45% yield, respectively. The pro-
change with PF6Ϫ, 8 was recovered as a red powder. The gress of the cyclisation reactions can be monitored by the
1
preparation of the analogous precursor 9 requires the iso- disappearance of the characteristic H NMR signals of the
meric form cis-[(a,a)Ru(aphen)2(CH3CN)2](PF6)2 as the terminal olefins and the concomitant appearance of signals
axle of the rotaxane (see b in Figure 2). It is itself obtained corresponding to the cyclic olefin in its cis and trans iso-
by solvolysis of the dichloride derivative cis-[(a,a)Ru(a- meric forms. The electronic and mass spectra (FAB-MS) as
1
phen)2Cl2] (Figure 3).
well as the assignment of their H NMR spectra (ROESY
experiments) confirm the expected structures of 1 and 2.
Upon irradiation at 404 nm (isosbestic point, see below)
of an acetonitrile solution of 1, a photochemical reaction is
triggered that can be monitored by absorption and 1H
NMR spectroscopy. The starting 2.5 ϫ 10Ϫ5  red solution
of 1 gradually changes its colour into yellow, as a con-
sequence of the changes in position and intensity of the
MLCT absorption bands. In particular, the band that
peaked at 450 nm decreases with irradiation time and a new
absorption band with a maximum at 380 nm grows (Fig-
ure 4).
Figure 3. Schematic view of the isomeric complexes for the general
species cis-[Ru(aphen)2Cl2]2ϩ (a for axial, e for equatorial)
The use of an unsymmetrical ligand such as 4-(p-anisyl)-
1,10-phenanthroline (aphen) is a challenging task since ste-
reo- and geometric isomers are expected. The sequential ad-
dition of different bidentate polypyridyl ligands onto the
ruthenium centre is actually described in the literature but
several attempts following these methodologies failed.[13,14]
Recently, [Ru(CH3CN)4Cl2] was used by von Zelewsky et
al.[15] to prepare ruthenium bis-chloro complexes with a bis-
bidentate ligand (chiragen). With this starting material and
two equivalents of aphen a statistical mixture of three iso-
mers as represented in Figure 3 was recovered in 46% yield.
The separation of the geometric isomer cis-[(a,a)Ru-
(aphen)2Cl2] from the mixture turned out to be possible on
Figure 4. Changes in the electronic absorption spectra of a 2.5 ϫ
10Ϫ5  acetonitrile solution of 1 under irradiation with a 150 W
xenon lamp at 404 nm. Spectra are recorded at t ϭ 0, 2, 5, 10, 15,
20, 30, 45, 60, 90, 120 min of irradiation
Neat isosbestic points appear at 342 and 404 nm, em-
silica columns and on numerous acidic alumina columns phasising the selectivity of the photochemical process and
with a yield of 87% being obtained. The identification of the final spectrum (Figure 4) is identical to that of the cis-
each isomer was made possible by analysing their 1H NMR [Ru(phen)2(CH3CN)2]2ϩ species. Importantly, 1 is stable
spectra (COSY and ROESY experiments). On heating the when kept in the dark for indefinite periods. The experi-
cis-[(a,a)Ru(aphen)2Cl2] isomer in a CH3CN/H2O (50:50) mental data led us to conclude that an efficient photolabilis-
mixture the bis-acetonitrile derivative cis-[(a,a)Ru- ation of the [Ru(phen)2]2ϩ unit takes place, analogous with
(aphen)2(CH3CN)2] was isolated as a single isomer proving the results obtained for the simpler [Ru(phen)2(dmbp)]2ϩ
that no isomerisation occurs under these conditions. The complex.[7] Notably, in the case of 1, under the same experi-
reaction of ligand 7 with the complex cis-[(a,a)Ru- mental conditions (150 W xenon lamp, λexc ϭ 404 nm) the
(aphen)2(CH3CN)2](PF6)2 gave the precursor complex 9 in time required to complete the reaction (120 min) is longer
90% yield.
than that for [Ru(phen)2(dmbp)]2ϩ (50 min), suggesting that
The cyclisation of the two terminal olefinic functions fol- the expulsion of the dmbp-containing macrocycle is kin-
lowing the method developed by Grubbs et al.[16] (ring clos- etically less favoured than the loss of a plain dmbp ligand
ing metathesis or RCM) turned out to be efficient. This in [Ru(phen)2(dmbp)]2ϩ, due to steric hindrance.
Eur. J. Inorg. Chem. 2003, 467Ϫ474
469

A.-C. Laemmel, J.-P. Collin, J.-P. Sauvage, G. Accorsi, N. Armaroli
FULL PAPER
1
Experiments performed by H NMR spectroscopy con- [Ru(phen)2dmbp]2ϩ and 1, respectively. Since the steric
firmed the above results. The spectrum obtained after irra- hindrance is more pronounced in than in
1
diating an NMR tube containing 1 in CD3CN corresponds [Ru(phen)2dmbp]2ϩ, it seems that some decoordination
to a mixture of cis-[Ru(phen)2(CD3CN)2]2ϩ and the free steps of the chelate unit are slower due to the presence of
macrocycle m-36. Once again, the efficiency of this photo- the macrocyclic chain. The cyclic nature of the complex is
chemical reaction is found to decrease in comparison with also expected to favour a cis conformation of the alkene
the previously studied system in which a [Ru(phen)2]2ϩ core group of the bipy-based macrocycle, making the stepwise
is associated with dmbp.[7]
Complexes 1 and [Ru(phen)2dmbp]2ϩ are not lumines- constrained analogue, dmbp.
decomplexation slightly more difficult than it is with its un-
cent at room temperature due to thermally induced deac-
After irradiation, it was possible to quantitatively recover
tivation of the potentially luminescent MLCT state via the complex 1 by refluxing the equimolar mixture of cis-
upper lying MC level (possibly leading to photodissoci- [Ru(phen)2(CH3CN)2]2ϩ and macrocycle m-36 in ethylene
ation, see above). Lowering the temperature prevents this glycol for two hours. The principle of the photochemically
thermal deactivation process. Very intense, long-lived lu- driven motion and the thermal backward reaction is indic-
minescence is observed at 77 K for both compounds ated in Scheme 3.
(Table 1, Figure 5). cis-[Ru(phen)2(CH3CN)2]2ϩ also ex-
hibits intense MLCT luminescence at 77 K, and its max-
imum peak is substantially blue-shifted relative to 1 and
[Ru(phen)2dmbp]2ϩ [18]
Notably, after irradiation the emis-
.
sion spectra of 1 and [Ru(phen)2dmbp]2ϩ strongly resemble
that of cis-[Ru(phen)2(CH3CN)2]2ϩ, revealing the presence
of only a small residual amount (Ͻ 10%) of starting mat-
erial (see spectral shoulder at 625 nm, Table 1). The excited
state lifetime (3.0 µs) also strongly supports the view that
photochemical induced expulsion of the bipy-type fragment
has occurred, leading to the formation of
a cis-
[Ru(phen)2(CH3CN)2]2ϩ coordination centre for both com-
plexes.
Scheme 3
The photochemical behaviour of complex 2 has also been
studied under similar conditions as for complex 1, i.e. with
an efficiency similar to that observed for the same process
in 1. However, a careful examination of the area around the
isosbestic point (417 nm) shows that some by-products were
formed during the photoirradiation. By monitoring the
photochemical reaction using 1H NMR spectroscopy
(CD3CN, 500 MHz) the appearance of the free macrocycle
is concomitant with the formation of the three isomeric
forms of the complex cis-[Ru(aphen)2(CD3CN)2]2ϩ in the
ratio 1(a,a)/2(a,e)/1(e,e). This experiment suggests that a
photochemical isomerisation of the primary photo-product
cis-[(a,a)Ru(aphen)2(CD3CN)2]2ϩ takes place at a similar or
higher rate than that of the photosubstitution of the macro-
Figure 5. Emission spectra at 77 K of a CH3CN rigid matrix of 1
before (full line, λexc ϭ 449 nm) and after (dotted line, λexc
ϭ
420 nm) irradiation and of cis-[Ru(phen)2(CH3CN)2]2ϩ (dashed
line, λexc ϭ 420 nm). O. D. ϭ 0.5 for all samples at the excitation
wavelength
At 25 °C, quantum yields for photolabilisation are cycle m-36. A bis-phenanthroline ligand[19], that is able to
0.020 Ϯ 0.002 and 0.008 Ϯ 0.001 in the case of stabilise the ruthenium core in a single isomeric form, is
Table 1. Luminescence Properties of the CH3CN rigid matrix at 77 K
[Ru(phen)2dmbp]2ϩ
before irradiation
592, 644
[Ru(phen)2dmbp]2ϩ
after irradiation
545, 584, 625(sh)
1
1
[Ru(phen)2(CH3CN)2]2ϩ
before irradiation
584, 634
after irradiation
545, 584, 625(sh)
[a]
λmax
545, 584
3.0
(nm)
τ[b] (µs)
2.7
3.0
5.7
3.0
[a]
Band maxima from uncorrected emission spectra, excitation wavelengths are the maxima of the room temperature MLCT absorption
spectra, namely 450 nm for [Ru(phen)2dmbp]2ϩ and 1 before irradiation and 420 nm for these compounds after irradiation and
[Ru(phen)2(CH3CN)2]2ϩ
.
Excited state lifetimes, λexc ϭ 337 nm.
[b]
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Eur. J. Inorg. Chem. 2003, 467Ϫ474

Macrocyclic Complexes of [Ru(N-N)2]2ϩ Units
FULL PAPER
and recrystallised from ethyl acetate. A sand-brown powder was
isolated (10.0 g, 0.035 mol) in 25% yield. Sand-brown powder (m.p.
138 °C). 1H NMR (CD2Cl2, 200 MHz): δ ϭ 9.14 (dd, J ϭ 4.18 and
1.48 Hz, 1 H, 9-H), 9.12 (d, J ϭ 4.42 Hz, 1 H, 2-H), 8.26 (dd, J ϭ
7.99 and 1.85 Hz, 1 H, 7-H), 7.75 (d, J ϭ 9.10 Hz, 1 H, 5-H), 7.68
(d, J ϭ 9.10 Hz, 1 H, 6-H), 7.64 (ddJ ϭ 7.99 and 4.31 Hz, 1 H, 8-
H,), 7.55 (d, J ϭ 4.66 Hz, 1 H, 3-H), 7.49 (d, J ϭ 8.84 Hz, 2 H,
Ho), 7.09, J ϭ 8.86 Hz(d, 2 H, Hm), 3.90 (s, 3 H, Me) ppm.
C19H14N20: calcd. C 79.70, H 4.93, N 9.78; found C 78.74, H 5.05,
N 8.23.
needed to circumvent this undesirable process. Preliminary
experiments show that no photoisomerisation occurs when
the phenanthroline ligands are linked by a p-xylyl bridge.
We are currently working on a ruthenium complex that in-
corporates both this bis-phenanthroline ligand and a bipy-
based macrocycle.
Experimental Section
Physical Measurements: 1H NMR spectra were obtained with
Bruker WP200 SY (200 MHz), Bruker AM 400 and ARX 500(400
and 500 MHz, respectively) spectrometers. Chemical shifts reported
are referenced to Me4Si as an internal standard. All the photo-
chemical and photophysical experiments were carried out in ace-
tonitrile (CarloϪErba for spectroscopy). The absorption spectra
were recorded with a PerkinϪElmer λ5 spectrophotometer. Emis-
sion spectra were obtained with a Spex Fluorolog II spectrofluori-
meter (continuous 150-W Xe lamp), equipped with a Hamamatsu
R-928 photomultiplier tube. Excited state lifetimes were determined
with an IBH single photon counting spectrometer equipped with a
thyratron gated nitrogen lamp working in the 4Ϫ30 kHz range
(λexc ϭ 337 nm, 0.5 ns time resolution); the detector was a red-
sensitive (185Ϫ850 nm) Hamamatsu R-3237Ϫ01 photomultiplier
tube.
6,6Ј-Bis(γ-tetrahydropyranylpropyl)-2,2Ј-bipyridine (4): A 1.64 
nBuLi (14.0 mL, 23.0 mmol) solution was added dropwise to a so-
lution of diisopropylamine (3.4 mL, 24.3 mmol) in THF (21 mL),
under argon. A degassed solution of 6,6Ј-dmbp (2.0 g, 10.8 mmol)
in anhydrous THF (20 mL) was cooled to Ϫ 78 °C and the freshly
prepared LDA solution was added via a cannula. The solution
turned from yellow to blue-purple and was stirred for a further 2 h
at Ϫ 78 °C, after which the temperature was allowed to rise to 5
°C. The deep red solution was once again cooled to Ϫ 78 °C. Mean-
while, a solution of tetrahydropyrannyl-2-bromoethyl-ethyl (4.7 g,
24.0 mmol) in anhydrous THF (5 mL) was cooled to Ϫ 78 °C and
degassed. This solution was then transferred, under argon, to the
solution of 6,6Ј-dmbp at Ϫ 78 °C and the mixture turned deep
green. The solution was then stirred for 16 h at room temperature.
The clear orange-brown solution was hydrolysed with water (80
mL) and turned yellow. After the solvent was removed and the
residue treated with CH2Cl2, the organic layers were washed with
water, dried over MgSO4, and the solvent was evaporated. The re-
sulting orange oil was purified by column chromatography on alu-
mina (eluent: hexane/diethyl ether, 50:50). The product was ob-
tained in 63% yield (3.0 g, 6.8 mmol). Yellow oil. 1H NMR
(CD2Cl2, 200 MHz): δ ϭ 8.26 (dd, J ϭ 7.87 Hz, 0.99 Hz, 2 H, 3,3Ј-
H), 7.71 (t, J ϭ 7.74 Hz, 2 H, 4,4Ј-H), 7.18 (dd, J ϭ 7.60 and
0.99 Hz, 2 H, 5,5Ј-H), 4.57 (t, J ϭ 3.44 Hz, 2 H, Ha), 3.80 (m, 4
H, He), 3.41 (m, 4 H, Hγ), 2.93 (t, J ϭ 7.75 Hz, 4 H, Hα), 2.12 (m,
4 H, Hβ), 1.59 (m, 12 H, Hb,c,d) ppm.
Photochemical reactions were performed as follows: dilute solu-
tions of the complexes (about 2.5 ϫ 10Ϫ5 ), were put into 1 cm
path spectrophotometric cuvettes and irradiated under continuous
stirring with a 150 W xenon lamp (Osram XBOW/1) at 404 nm
using slits of 2.5 mm (9.4 nm) at the entrance and exit of a Spex
1681 0.22M monochromator. At the end of the photoreaction, after
removing CH3CN under vacuum, the orange residue was dried
under
vacuum to give, quantitatively, the complex
[Ru(phen)2(CH3CN)2]2ϩ and the macrocycle.
Quantum yields of the photoreaction at 436 nm were obtained by
measuring the intensity of the light source with the ‘‘micro-version’’
of the ferric oxalate actinometer.[20]
6,6Ј-Bis(γ-hydroxypropyl)-2,2Ј-bipyridine (5): The bipyridine deriv-
ative 4 (2.90 g, 6.61 mmol) was dissolved in 95% EtOH (45 mL)
and heated to reflux. A spatula of p-toluenesulfonic acid (1.27 g,
6.54 mmol) was then added. The reaction was followed by TLC
(SiO2, eluent: CH2Cl2/5% MeOH) and the reflux was maintained
for 4 h. Additional aliquots of acid (0.80 g, 4.12 mmol) were added
Synthesis of Ligands and Complexes
Some ligands and complexes were prepared following literature
procedures: 3-chloro-1-(p-methoxyphenyl)propanone,[21] 6,6Ј-di-
methyl-2,2Ј-bipyridine (6,6Ј-dmbp),[10] cis-[Ru(phen)2(CH3CN)2]- and the solution was refluxed for a further 4 h. The ethanol was
(PF6)2,[12] [Ru(phen)2(6,6Ј-dmbp)](PF6)2.[7] All charged species
then removed and the residue was dissolved in a CH2Cl2/H2O mix-
ture. After neutralisation by an aqueous solution of K2CO3, the
aqueous phase was extracted 3 times with CH2Cl2 and the organic
layers were washed with water, dried over MgSO4, filtered and the
solvent evaporated. The crude mixture was purified by column
chromatography on silica (eluent: CH2Cl2/MeOH, 94.5:5.5) to give
Ϫ
were isolated as PF6 salts. The solvents were distilled over the
appropriate drying agents.
4-(p-Anisyl)-1,10-phenanthroline (aphen): In a three-neck round-
bottomed flask equipped with a reflux condenser and a thermo-
meter, a mixture of 8-aminoquinoline (20.0 g, 0.139 mol), arsenic
pentoxide As2O5 (18.7 g, 0.081 mol), concentrated H2SO4 (30 mL)
and H2O (10 mL) was heated to 100 °C under strong magnetic
stirring. 3-chloro-1-(p-methoxyphenyl)propanone (39.0 g, 0.197
mol) was then added rapidly. The reaction mixture was heated at
reflux for 2.5 h, and then poured onto ice and made alkaline with
1
the product (1.24 g, 4.55 mmol) in 69% yield. Yellow oil. H NMR
(CD2Cl2, 200 MHz): δ ϭ 8.09 (dd, J ϭ 7.75 Hz, 0.61 Hz, 2 H, 3,3Ј-
H), 7.75 (t, J ϭ 7.74 Hz, 2 H, 4,4Ј-H), 7.21 (dd, J ϭ 7.75 Hz,
0.87 Hz, 2 H, 5,5Ј-H), 3.90 (br. s, 2 H, OH), 3.68 (t, J ϭ 5.91 Hz,
4 H, Hγ), 3.01 (t, J ϭ 6.89 Hz, 4 H, Hα), 2.01 (m, 4 H, Hβ) ppm.
concentrated aqueous 7  KOH. After addition of CH2Cl2, the Bis-THP Derivative of 2,2Ј-Bipyridine (6): A degassed solution of 5
organic phase was separated, the aqueous layer was extracted 5 (1.19 g, 4.36 mmol) in DME (25 mL) was added dropwise at 0 °C
times with CH2Cl2 (500 mL) and the combined organic layers were
washed with water (3 times), then dried over MgSO4. The black oil
was collected by filtration, washed with CH2Cl2 and was purified
by repeated chromatography (silica, CH2Cl2, eluent: CH2Cl2/
MeOH, 97:3; alumina, hexane/ether, 50:50, eluent: CH2Cl2/MeOH,
under argon to a suspension of NaH (0.60 g, 13.7 mmol) in DME
(50 mL) for 40 min, upon which the mixture turned white. The ice
bath was removed and at room temperature a degassed solution
of 2-[2-(chloroethoxy)ethoxy)]ethoxy}tetrahydro-2H-pyran (3.64 g,
14.40 mmol) in DME (35 mL) was added dropwise to the mixture
95:5; alumina, ether/EtOAc, 50:50, eluent: CH2Cl2/MeOH, 99:1) which was then heated at 50 °C for 3 h after which the temperature
Eur. J. Inorg. Chem. 2003, 467Ϫ474 471

A.-C. Laemmel, J.-P. Collin, J.-P. Sauvage, G. Accorsi, N. Armaroli
FULL PAPER
was increased and the reaction heated at reflux for 14 h. The reac-
tion was monitored by TLC (Alumina, eluent: CH2Cl2/5% MeOH).
More NaH (0.21 g, 4.80 mmol) and a solution of tetrahydropyran-
nyl derivative (2.00 g, 7.91 mmol) in DME (20 mL) was added. The
reaction mixture was maintained under reflux under argon for a
further 34 h, then it was cooled to 0 °C. Excess NaH was neut-
ralised by the gradual addition of EtOH until no further evolution
of gas was observed (12 mL overall). The solvent was then evapor-
ated and the residue was dissolved in a 1:1 H2O/CH2Cl2 mixture.
The organic layer was separated, and the aqueous layer was ex-
filtration of the solution and removal of the solvent, the oily residue
was purified twice by column chromatography on alumina (eluent:
CH2Cl2/MeOH, 99.5:0.5) to afford 3 (0.89 g, 1.44 mmol) in 75%
1
yield. Pale yellow oil. H NMR (CDCl3, 200 MHz): δ ϭ 8.24 (d,
J ϭ 7.86 Hz, 2 H, 3,3Ј-H), 7.68 (t, J ϭ 7.75 Hz, 2 H, 4,4Ј-H), 7.14
(dd, J ϭ 7.62 and 0.98 Hz, 2 H, 5,5Ј-H), 5.91 (ddt, J ϭ 17.22, 10.32
and 5.66 Hz, 2 H, HЈ), 5.26 (dtd, J ϭ 17.10, 3.44 and 1.60 Hz,
2 H, Ht), 5.16 (m, J ϭ 10.32, 1.72 and 1 Hz, 2 Hc), 4.01 (dt,
J ϭ 5.66 and 1.36 Hz, 4 H, Hg), 3.67Ϫ3.50 (m, 28 H, Ha,b,c,d,e,f
,
4 Hγ), 2.92 (t, J ϭ 7.50 Hz, 4 H, Hα), 2.11 (tt, J ϭ 6.52 and 6.88 Hz,
tracted 4 times with CH2Cl2. The organic layers were combined, 4 Hβ) ppm. FAB-MS for C34H52N2O8: m/z ϭ 617.5 [M ϩ H]ϩ,
washed with water, dried over MgSO4 and filtered. Following evap-
oration of the solvent, the orange oil was purified twice by column
chromatography on alumina eluting with a CH2Cl2/MeOH mixture
(98.7:1.3; 99.9:0.1). Pure 6 was isolated (0.65 g, 0.92 mmol) along
with a mixture of the starting material and of the monosubstituted
product (1.30 g) which was treated as follows. This mixture was
added to a suspension of DMSO (10 mL) containing KOH powder
(3.16 g, 47.60 mmol). To this orange-brown solution, tetrahydropy-
rannyl derivative (4.81 g, 19.04 mmol) was added and the stirring
was maintained for 3.5 h.. The mixture was then heated at 50 °C
for 35 min. After cooling and addition of H2O/CH2Cl2, the organic
phase was separated and the aqueous phase was extracted with
CHCl3 (twice, 150 mL) and also CH2Cl2 (twice, 150 mL). The com-
bined organic layers were washed, dried over MgSO4, filtered and
the solvents evaporated. The crude oil was purified four times by
column chromatography on alumina (CH2Cl2/MeOH, 98:0.2;
99.6:0.4) to give pure 7 (0.99 g, 1.41 mmol). The overall yield of 7
(1.64 g, 2.33 mmol) from the two reactions was 53%. Colourless
calcd. 617.4, 100%.
cis-[Ru(aphen)2Cl2]: Following the complete dissolution of complex
[Ru(CH3CN)4Cl2] (410.0 mg, 1.22 mmol) in a degassed solution of
1,2-dichloroethane (130 mL), the ligand aphen (684.0 mg,
2.39 mmol) was added and the orange-brown mixture was heated
at reflux for 2 h. After evaporation of the solvent, the purple-brown
residue was purified twice by flash chromatography on silica gel
(Silica gel 60, 0.063Ϫ0.200 mm, Merck 7734) eluting with EtOH.
The mixture of isomeric complexes cis-[Ru(aphen)2Cl2] was ob-
tained in 46% yield (412.5 mg, 0.55 mmol). The complexes ob-
tained were purple in colour.
Separation of the Three Isomers of cis-[Ru(aphen)2Cl2]
The three isomers (460 mg, 0.620 mmol) were separated 13 times
by flash chromatography on alumina (aluminium oxide 90, acidic,
activity I, 0.063Ϫ0.200 mm, Merck 1078). The eluent was a mixture
of CH2Cl2/MeOH (3%). The purple isomer (a,a), which migrates
as the first band, (100 mg, 0.134 mmol) was isolated as 87% of the
theoretical yield (25%).
1
oil. H NMR (CDCl3, 200 MHz): δ ϭ 8.23 (d, J ϭ 7.51 Hz, 2 H,
3,3Ј-H), 7.68 (t, J ϭ 7.75 Hz, 2 H, 4,4Ј-H), 7.14 (d, J ϭ 7.62 Hz, 2
H, 5,5Ј-H), 4.62 (t, J ϭ 3.32 Hz, 2 H, Ha), 3.84 (m, 4 H, He), 3.64
(m, 24 H, 6 ϫ ϪCH2ϪCH2Ϫ), 3.55 (t, 4 H, Hγ), 2.92 (t, J ϭ
7.63 Hz, 4 H, Hα), 2.11 (tt, 4 H, Hβ), 1.90Ϫ1.30 (m, 12 H, 4 Hb, 4
Hc, 4 Hd) ppm.
Isomer (a,a): 1H NMR (CD2Cl2, 400 MHz): δ ϭ 10.50 (d, J ϭ
5.56 Hz, 2 H, 2-H), 8.23 (, J ϭ 9.04 Hz d, 2 H, 5-H), 7.98 (d, J ϭ
5.52 Hz, 2 H, 3-H), 7.97 (dd, J ϭ 7.96 and 1.12 Hz, 2 H, 7-H),
7.93 (dd, J ϭ 5.44 and 1.00 Hz, 2 H, 9-H), 7.88 (d, J ϭ 9.28 Hz, 2
H, 6-H), 7.71 (d, J ϭ 8.64 Hz, 4 H, Ho), 7.21 (d, J ϭ 8.60 Hz, 4
H, Hm), 7.19 (m, 2 H, 8-H), 3.96 (s, 6 H, 2 Me) ppm. UV/Vis
(CH2Cl2): λ ϭ 553 (7400) nm. Isomer (a,e): 1H NMR (CD2Cl2, 200
MHz): δ ϭ 10.43 (m, 2 H, 2-Ha, 9-He), 8.43 (dd, J ϭ 8.12 Hz, 1
H, 7-He), 8.23 (d, J ϭ 9.10 Hz, 1 H, 5-Ha), 8.04 (dd, 2 H, 5-He, 6-
He), 8.00Ϫ7.85 (m, 4 H, 3-Ha, 7-Ha, 9-Ha, 8-He), 7.86 (d, J ϭ
9.10 Hz, 1 H, 6-Ha), 7.70 (d, J ϭ 8.86 Hz, 2 H, Ho,a), 7.70 (m, 1
H, 2-He), 7.38 (d, J ϭ 8.86 Hz, 2 H, Ho,e), 7.20 (d, J ϭ 8.86 Hz, 2
H, Hm,a), 7.19 (m, 2 H, 8-Ha, 3-He), 7.04 (d, J ϭ 8.86 Hz, 2 H,
Hm,e), 3.95 (s, 3 H, Me a), 3.86 (s, 3 H, Mee) ppm. UV/Vis
(CH2Cl2): λ ϭ 550 (9200) nm. Isomer (e,e): 1H NMR (CD2Cl2, 400
MHz): δ ϭ 10.48 (m, 2 ϫ 9-H), 8.43 (d, J ϭ 7.72 Hz, 2 H, 7-H),
8.06 (d,J ϭ 8.80 Hz, 2 H, 6-H), 8.03 (, J ϭ 9.16 Hz d, 2 H, 5-H),
8.01 (m, 2 H, 8-H), 7.71 (d, J ϭ 8.80 Hz, 2 H, 2-H), 7.38 (dd, J ϭ
8.44 Hz, 4 H, Ho), 7.20 (d, J ϭ 8.80 Hz, 2 H, 3-H), 7.04 (d, J ϭ
8.44 Hz, 4 H, Hm), 3.86 (s, 6 H, 2 Me) ppm. UV/Vis (CH2Cl2): λ ϭ
547 (5800) nm.
2,2’-Bipyridine 7: 6 (1.62 g, 2.30 mmol) was heated to reflux in 95%
EtOH (16 mL) and then p-toluenesulfonic acid (0.45 g, 2.30 mmol)
was added. The reaction was followed by TLC (SiO2; eluent:
CH2Cl2/5% MeOH) and reflux was maintained for 27 h. After
evaporation of the solvent, the residue was dissolved in a CH2Cl2/
H2O mixture and neutralised with an aqueous solution of
NaHCO3. The aqueous phase was extracted 3 times with CH2Cl2
and the organic layers were combined, washed with water, dried
over MgSO4 and the solvent was evaporated. 6 was isolated (1.03 g,
1.92 mmol) in 84% yield and was used without further purification
(purity Ͼ 95% by NMR). Colourless oil. 1H NMR (CDCl3,
200 MHz): δ ϭ 8.23 (d, J ϭ 7.25 Hz, 2 H, 3,3Ј-H), 7.69 (t, J ϭ
7.75 Hz, 2 H, 4,4Ј-H), 7.15 (dd, J ϭ 7.64 and 0.77 Hz, 2 H, 3,3Ј-
H), 3.80Ϫ3.52 (m, 26 H, 2 ϫ ϪOH, 6 ϫ ϪCH2ϪCH2Ϫ), 3.56 (m,
4 H, Hγ), 2.92 (t, J ϭ 7.63 Hz, 4 H, Hα), 2.12 (tt, 4 H, Hβ) ppm.
3: In a degassed solution of 7 (1.03 g, 1.92 mmol) in DME (45 mL),
NaH (0.93 g, 21.3 mmol) was added with a spatula and the mixture
was heated to 50 °C. Allyl bromide (16 mL, 181.00 mmol) was then
added via the cannula transfer technique. The reaction mixture was
heated at reflux for 20 h and then monitored by TLC (Alumina;
cis-[(a,a)Ru(aphen)2(CH3CN)2](PF6)2: In a round bottomed flask,
cis-[(a,a)Ru(aphen)2Cl2] (80 mg, 0.107 mmol) was heated at reflux
under argon in a mixture of CH3CN/H2O 50:50 (12 mL) for 2.5 h.
After cooling to room temperature, a saturated solution of aqueous
CH2Cl2/5% MeOH). The white solution was cooled to 0 °C and KPF6 (10 mL) and CH3CN (5 mL) were added. The evaporation
excess NaH was neutralised by adding small portions (3 mL) of of the solvent caused a brown-orange solid to precipitate that was
absolute ethanol until there was no further evolution of gas. The
solvent was then evaporated and the residue dissolved in a CH2Cl2/
H2O (1:1) mixture. The organic phase was separated and the aque- in a yield of 45% (50 mg, 0.048 mmol). Brown-orange powder. H
separated by filtration, washed with water and diethyl ether and
then air-dried. cis-[(a,a)Ru(aphen)2(CH3CN)2](PF6)2 was obtained
1
ous phase was extracted 4 times with CH2Cl2. The organic phases
NMR (CD2Cl2, 200 MHz): δ ϭ 9.76 (d, J ϭ 5.40 Hz, 2 H, 2-H),
were combined, washed with H2O and dried over MgSO4. After 8.38 (d, J ϭ 9.10 Hz, 2 H, 5-H), 8.35 (dd, J ϭ 8.36 Hz, 1.24 Hz, 2
472
Eur. J. Inorg. Chem. 2003, 467Ϫ474

Macrocyclic Complexes of [Ru(N-N)2]2ϩ Units
FULL PAPER
H, 7-H), 8.20 (d, J ϭ 5.42 Hz, 2 H, 3-H), 8.04 (d, J ϭ 9.10 Hz, 2
1435.3 [M Ϫ PF6]ϩ, calcd. 1435.4, 5%, 1289.4 [M Ϫ 2 PF6 ϩ eϪ]ϩ,
H, 6-H), 7.87 (dd, J ϭ 5.41 and 1.23 Hz, 2 H, 9-H), 7.76 (d, J ϭ calcd. 1290.5, 6%; 674.1 [M Ϫ 2 PF6Ϫ3 ϩ eϪ]ϩ, calcd. 674.1, 46%.
8.84 Hz, 4 H, Ho), 7.50 (dd, J ϭ 5.29 and 8.25 Hz, 2 H, 8-H), 7.25
[Ru(aphen)2(m-36)](PF6)2 (2): To a degassed Schlenk containing 9
(d, J ϭ 8.60 Hz, 4 H, Hm), 3.97 (s, 6 H, 2 Me) ppm.
(68.8 mg, 0.044 mmol) and the catalyst [Ru], 3 mg, 8% mol), freshly
distilled and degassed CH2Cl2 (5 mL) was added via a cannula to
Compound 8:
(CH3CN)2](PF6)2 (69.7 mg, 0.084 mmol) and
A
stoichiometric mixture of cis-[Ru(phen)2-
(51.8 mg,
obtain a 0.01  solution. This mixture was stirred at room temper-
ature for one day during which a syringe needle was periodically
inserted into the reaction vessel to allow the escape of ethylene gas.
A further 9 mol percent of the catalyst (3.5 mg) was added and
after 4 days further solvent added in order to maintain the desired
concentration of the reaction mixture. Further catalyst (5 mg, 14%
mol) was added. The stirring was continued for 1 day (overall dura-
tion of reaction: 6 days). The solvent was then evaporated and ad-
dition of water (3 mL) and a saturated solution of aqueous KPF6
(5 mL) allowed the precipitation of a crude product which was col-
lected by filtration, washed with water and diethyl ether and was
purified by chromatography (silica, eluent: acetone/H2O/KNO3,
100:7:0.7; alumina, eluent: toluene/CH3CN 35:65; alumina, eluent:
toluene/CH3CN, 40:60). 2, not completely pure, was isolated
(30.4 mg, 0.020 mmol) in 45% yield. Preparative chromatography
on silica (eluent: CH3CN/H2O/KPF6, 100:10:2), performed twice,
afforded pure 2. Red compound. 1H NMR (CD3CN, 500 MHz):
δ ϭ 8.45 (dd, J ϭ 8.25 and 1.15 Hz, 2 H, 7-H), 8.42 (dd, J ϭ
5.55 Hz, 2 H, 2-H), 8.36 (d, J ϭ 9.55 Hz, 2 H, 3,3Ј-H), 8.34 (d,
J ϭ 9.10 Hz, 2 H, 5-H), 8.16 (d, J ϭ 9.25 Hz, 2 H, 6-H), 7.97 (dd,
J ϭ 7.85 and 8.15 Hz, 2 H, 4,4Ј-H), 7.80 (d, J ϭ 5.55 Hz, 2 H, 3-
H), 7.74 (dd, J ϭ 5.32 and 1.17 Hz, 2 H, 9-H), 7.67 (d, J ϭ 8.75 Hz,
4 H, Ho), 7.46 (dd, J ϭ 5.37 and 8.17 Hz, 2 H, 8-H), 7.29 (d, J ϭ
7.85 Hz, 2 H, 5,5Ј-H), 7.23 (d, J ϭ 8.95 Hz, 4 H, Hm), 5.34 (m, 2
H, Hc), 5.21 (m, 2 H, Ht,), 3.92 (s, 6 H, 2 OMe), 4.30Ϫ0.08 (m, 40
H, Ha,b,c,d,e,f,g,α,β,γ) ppm. FAB-MS for RuC70H76N6O10P2F12: m/z ϭ
1407.2 [M Ϫ PF6]ϩ, calcd. 1407.4, 8%; 1262.3 [M Ϫ 2 PF6 ϩ eϪ]ϩ,
calcd. 1262.4, 9%; 674.0 [M Ϫ 2 PF6 Ϫ m-36 ϩ eϪ]ϩ, calcd. 674.1,
78%. UV/Vis (CH3CN): λ ϭ 457 (9700) nm.
3
0.084 mmol) was heated at 140 °C in degassed ethylene glycol
(6 mL) for 2 h. After cooling to room temperature, water (8 mL)
and then a saturated solution of aqueous KPF6 (6 mL) were added.
The precipitate obtained was collected by filtration and washed
with water and diethyl ether. The crude product was purified by
chromatography on silica gel eluting with an acetone/water/aque-
ous saturated KNO3 (100:4:2) mixture. The cation was precipitated
from the eluent by addition of an aqueous solution of KPF6 and
the resultant solid was filtered off to give 8 (86.2 mg, 0.063 mmol)
1
in 75% yield. Red compound. H NMR ([D6]acetone, 200 MHz):
δ ϭ 8.94 (dd, J ϭ 8.15 and 1.10 Hz, 2 H, 4-H), 8.74 (dd, J ϭ 5.17
and 1.22 Hz, 2 H, 2-H), 8.67 (dd, J ϭ 8.35 and 1.22 Hz, 2 H, 7-
H), 8.63 (d, J ϭ 8.86 Hz, 2 H, 3,3Ј-H), 8.47 (d, J ϭ 8.86 Hz, 2 H,
5-H), 8.38 (d, J ϭ 8.86 Hz, 2 H, 6-H), 8.10 (dd, J ϭ 7.86 and
7.88 Hz, 2 H, 4,4Ј-H), 8.10 (dd, J ϭ 5.23 and 8.24 Hz, 2 H, 3-H),
7.97 (dd, J ϭ 5.40 and 1.23 Hz, 2 H, 9-H), 7.62 (dd, J ϭ 5.28 and
8.24 Hz, 2 H, 8-H), 7.44 (dd, J ϭ 7.87 and 0.99 Hz, 2 H, 5,5Ј-H),
5.82 (, J ϭ 17.34, 10.44 and 5.23 Hz ddt, 2 H, HЈ), 5.18 (m, 2 H,
Ht), 5.04 (m, 2 H, Hc), 3.88 (dt, J ϭ 5.42 and 1.54 Hz, 4 H, Hg),
3.60Ϫ3.20 (m, 24 H, Ha,b,c,d,e,f), 3.20Ϫ1.00 (12 H, Hα,β,γ) ppm.
[Ru(phen)2(m-36)](PF6)2 (1): To a degassed Schlenk containing 8
(117.0 mg, 0.086 mmol) and the catalyst (Grubbs ruthenium() car-
bene: [Ru], (Scheme 2), 4.9 mg, 7% mol), freshly distilled and de-
gassed CH2Cl2 (8.5 mL) was added via a cannula to obtain a 0.01
 solution. This mixture was stirred at room temperature for 18 h
during which a syringe needle was periodically inserted into the
reaction vessel to allow the ethylene gas to escape. The reaction
1
was monitored by H NMR spectroscopy. A further 7 mol percent
of the catalyst was added and further solvent was added in order
to maintain the desired concentration of the reaction mixture. The
stirring was continued for 5 days. The solvent was then evaporated
and the crude product was purified by chromatography on silica
gel (eluent: acetone/H2O/KNO3, 100:5:2). Pure 1 was isolated
(77.2 mg, 0.058 mmol) in 67% yield. Red compound. 1H NMR
([D6]acetone, 200 MHz): δ ϭ 8.94 (dd, J ϭ 8.36 and 1.24 Hz, 2 H,
4-H), 8.76 (dd, J ϭ 5.41 and 1.23 Hz, 2 H, 2-H), 8.68 (dd, J ϭ 8.37
and 1.23 Hz, 2 H, 7-H), 8.62 (d, J ϭ 7.38 Hz, 2 H, 3,3Ј-H), 8.47
(d, J ϭ 8.86 Hz, 2 H, 5-H), 8.38 (d, J ϭ 8.86 Hz, 2 H, 6-H), 8.09
(dd, J ϭ 8.12 and 7.14 Hz, 2 H, 4,4Ј-H), 8.09 (dd, 2 H, 3-H), 7.92
(dd, J ϭ 5.29 and 1.11 Hz, 2 H, 9-H), 7.67 (dd, J ϭ 5.42 and
8.12 Hz, 2 H, 8-H), 7.43 (d, J ϭ 7.88 Hz, 2 H, 5,5Ј-H), 5.39 (m, 2
H, Hcis, 75%), 5.31 (m, 2 H, Htrans, 25%), 3.90Ϫ1.50 (m, 40 H, Hg,
Ha,b,c,d,e,f, Hα,β,γ) ppm. FAB-MS for RuC56H64N6O8P2F12: m/z ϭ
1195.3 [M Ϫ PF6]ϩ, calcd. 1195.3, 8%; 1049.3 [M Ϫ 2 PF6 ϩ eϪ]ϩ,
calcd. 1050.3, 11%; 462.0 [M Ϫ 2 PF6 Ϫ m36 ϩ eϪ]ϩ, calcd. 462.0,
32%. UV/Vis (CH3CN): 450 nm (9200).
Acknowledgments
This work was supported by the French CNRS and the Italian
CNR. We thank the European Commission COST programme
D11/0004/98, the French Ministry of Education, Research and
Technology for a fellowship to A.C.L., and the Italian MIUR for
a fellowship to G.A. (Progetto 5%). We are also grateful to Johnson
Matthey for a loan of RuCl3.
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