Synthesis and photochemistry of a two-position Ru(terpy)(phen)(L) 2+ scorpionate complex

Article abstract of DOI:10.1021/ic060029p

A dissymmetric 1,10-phenanthroline chelate (N-phen-S) bearing two polyether chains terminated by two monodentate ligands of the benzonitrile (N) and dialkylesulfoxide (S) types was synthesized, characterized, and coordinated to ruthenium. The corresponding Ru(terpy*)(N-phen-S)²⁺ complexes (terpy* = 4′-(3,5-ditertiobutylphenyl)-2,2′;6′,2″- terpyridine) were fully characterized as being two coordination isomers of the scorpionate type with one of the two tails occupying the sixth position on the coordination sphere. Photoexpulsion of the coordinated tail led to opening of the ruthena-macrocycle and subsequent rearrangement of the bidentate chelate. This rearrangement consisted of a 90° rotation of the phenanthroline around the ruthenium atom. Selective irradiation of one isomer in a mixture of the two was undertaken using band-pass filters; this resulted in an enrichment of the nonirradiated isomer in the mixture. Thermal back-coordination of the tail was investigated in the dark. It took place quantitatively from the corresponding ruthenium chloride complex by trapping of the anion with silver salts.

Full text of DOI:10.1021/ic060029p

Inorg. Chem. 2006, 45, 4024−4034
+
Synthesis and Photochemistry of a Two-Position Ru(terpy)(phen)(L)2
Scorpionate Complex
Sylvestre Bonnet, Jean-Paul Collin,* and Jean-Pierre Sauvage*
Laboratoire de Chimie Organo-Mine´rale, UMR 7513 du CNRS, Institut Le Bel, UniVersite´ Louis
Pasteur, 4 rue Blaise Pascal, 67000 Strasbourg Cedex, France
Received January 6, 2006
A dissymmetric 1,10-phenanthroline chelate (N-phen-S) bearing two polyether chains terminated by two monodentate
ligands of the benzonitrile (N) and dialkylesulfoxide (S) types was synthesized, characterized, and coordinated to
+
ruthenium. The corresponding Ru(terpy*)(N-phen-S)2 complexes (terpy*
) 4′-(3,5-ditertiobutylphenyl)-2,2′;6′,2′′-
terpyridine) were fully characterized as being two coordination isomers of the scorpionate type with one of the two
tails occupying the sixth position on the coordination sphere. Photoexpulsion of the coordinated tail led to opening
of the ruthena-macrocycle and subsequent rearrangement of the bidentate chelate. This rearrangement consisted
of a 90° rotation of the phenanthroline around the ruthenium atom. Selective irradiation of one isomer in a mixture
of the two was undertaken using band-pass filters; this resulted in an enrichment of the nonirradiated isomer in the
mixture. Thermal back-coordination of the tail was investigated in the dark. It took place quantitatively from the
corresponding ruthenium chloride complex by trapping of the anion with silver salts.
Introduction
triggered by electrochemical17-21 or chemical22-24 signals.
In particular, light irradiation has also been reported to
produce molecular movements, either alone9,25-30 or in
conjunction with a redox chemical reaction.17,18,31 Purely
photonic stimuli are particularly promising, as the environ-
Induction of molecular motion in a controlled fashion
under the action of an external signal, either to mimic some
of the functions of biological motors or in relation to artificial
molecular switches, machines, and devices, is particularly
challenging.1,2 As far as synthetic systems are concerned,
catenanes and rotaxanes occupy a special position,1,3-9 but
noninterlocking systems such as scorpionates, metal-trans-
locating ligands, or metallamacrocycles based on hemilabile
multidentate ligands have also been investigated.10-16 In
many systems, motion at the molecular level has been
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Commun. 2003, 188.
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(19) Armaroli, N.; Balzani, V.; Collin, J.-P.; Gavina, P.; Sauvage, J.-P.;
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(20) Poleschak, I.; Kern, J.-M.; Sauvage, J.-P. Chem. Commun. 2004, 4,
474.
(21) Korybut-Daszkiewicz, B.; Wieckowska, A.; Bilewicz, R.; Domagala,
S.; Wozniak, K. Angew. Chem., Int. Ed. 2004, 43, 1668.
(22) Jime´nez-Molero, M. C.; Dietrich-Buchecker, C.; Sauvage, J.-P. Angew.
Chem., Int. Ed. 2000, 39, 3284.
* To whom correspondence should be addressed. E-mail: sauvage@
chimie.u-strasbg.fr (J.-P.S.); jpcollin@chimie.u-strasbg.fr (J.-P.C.).
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4024 Inorganic Chemistry, Vol. 45, No. 10, 2006
10.1021/ic060029p CCC: $33.50
© 2006 American Chemical Society
Published on Web 04/21/2006

Two-Position Ru(terpy)(phen)(L)2+ Scorpionate Complex
Figure 1. Design of a two-position molecular scorpionate based on the Ru(terpy)(phen)(L)2+ moiety.
ment of the system in motion is not altered by the addition
of chemical entities. Most of these systems contain a
photoisomerizable group such as azobenzene or alkene. Our
group has proposed another approach for light-driven
machines based on multicomponent ruthenium(II) com-
plexes.26,32,33 In these systems, ligand photosubstitution
reactions are used to set the molecule in motion. Such a
process requires thermal population of the ligand-field excited
state (3LF) from the triplet metal-to-ligand charge-transfer
(3MLCT) excited state. In Ru(diimine)32+-based systems, the
ligand to be photoexpelled is a hindered chelate of the 6,6′-
dimethyl-2,2′-bipyridine type (dmbp) inscribed in a ring.
Another family of complexes with the general formula Ru-
(terpy)(phen)(L)2+ (where L is a monodentate ligand) has
also recently been investigated as new building blocks for
light-controlled molecular machines.11,34-36 Visible light
irradiation of such complexes leads to the selective expulsion
of the monodentate ligand L and subsequent replacement
by a solvent molecule. The syntheses of complexes of the
type Ru(terpy)(phen)(L)2+ were described with a large variety
of monodentate ligands (water, acetonitrile, benzonitrile
derivatives, pyridines substituted in the 3, 4 or 5 positions,
sulfoxides, and thioethers).35,36 The absorption maxima of
these complexes vary with the nature of the monodentate
ligands, from ∼430 nm for dialkylsulfoxides to 515 nm for
the chloride ion. Control of the irradiation wavelength should
allow selective photoexpulsion of one type of ligand in a
mixture of complexes with different coordinated monodentate
ligands, L.
(phen)(L)2+ core.11 It was a scorpionate molecule where a
monodentate ligand, L1, of the benzonitrile type was attached
to the terpyridine ligand by a long and flexible poly(ethylene
glycol) chain. The benzonitrile ligand was shown both in
solution and in the solid state to be coordinated to the
ruthenium atom. White light irradiation of the complex led
to selective and quantitative photoexpulsion of L1, with an
opening of the ruthena-macrocycle and replacement of the
benzonitrile by a solvent molecule. The presence of the
covalent arm allowed the monodentate ligand to stay close
to the complex, which resulted in an easy thermal back-
coordination of the benzonitrile ligand to the ruthenium
center. In neat acetone, the ring-closing reaction was
quantitative within 1 day at room temperature or 2 h at reflux.
This new scorpionate-type complex is based on a dissym-
metric 1,10-phenanthroline chelate bearing two tails func-
tionalized by a benzonitrile group and a dialkylesulfoxide
group (Figure 1).
In a Ru(terpy)(N-N)(L)2+ complex, when the bidentate
chelate N-N is dissymmetric, two different isomers may
exist.34 The change from one isomer to the other implies a
90° rotation of the bidentate chelate around the ruthenium
atom. As depicted in Figure 1, such a rotation changes the
ability of the two monodentate ligands to coordinate, as only
the one which is on the side of the coordination site may
bind to the metal (Figure 1). Once bound, the monodentate
ligands play the role of a wedge that holds the bidentate
chelate in one position or the other. A suitable combination
of monodentate ligands was L1 ) benzonitrile and L2 )
dialkylesulfoxide since it was important to avoid as much
overlapping of the 1MLCT absorption bands of both isomers
as possible so that selective irradiation could be performed.
The model complexes Ru(terpy*)(phen)(MeOBN)2+ and Ru-
(terpy*)(phen)(DMSO)2+ (terpy* ) 4′-(3,5-ditertiobutylphen-
yl)-2,2′;6′,2′′-terpyridine, MeOBN ) 2,6-dimethoxybenzoni-
In 2001, Schofield et al. synthesized one of the first
prototypes of a molecular machine based on the Ru(terpy)-
(25) Muraoka, T.; Kinbara, K.; Kobayashi, Y.; Aida, T. J. Am. Chem. Soc.
2003, 125, 5612.
(26) Collin, J.-P.; Jouvenot, D.; Koizumi, M.; Sauvage, J.-P. Eur. J. Inorg.
Chem. 2005, 1850.
(27) Mobian, P.; Kern, J.-M.; Sauvage, J.-P. Angew. Chem., Int. Ed. 2004,
43, 2392.
1
trile, and DMSO ) dimethyl sulfoxide) showed MLCT
absorption bands far enough from each other in the visible
region (465 and 431 nm, respectively).36 These two ligands
were attached to the phenanthroline chelate by rigid phenyl
linkers followed by flexible polyether “tails” (Scheme 1).
The length of these tails was estimated on CPK models of
both isomers of the ruthenium scorpionate.
(28) Norikane, Y.; Tamaoki, N. Organic Lett. 2004, 6, 2595.
(29) Perez, E. M.; Dryden, D. T. F.; Leigh, D. A.; Teobaldi, G.; Zerbetto,
F. J. Am. Chem. Soc. 2004, 126, 12210.
(30) Leigh, D. A.; Wong, J. K.; Dehez, F.; Zerbetto, F. Nature 2003, 424,
174.
(31) Brouwer, A. M.; Frochot, C.; Gatti, F. G.; Leigh, D. A.; Mottier, L.;
Paolucci, F.; Roffia, S.; Wurpel, G. W. H. Science 2001, 291, 2124.
(32) Baranoff, E.; Collin, J.-P.; Furusho, J.; Furusho, Y.; Laemmel, A.-C.;
Sauvage, J.-P. Inorg. Chem. 2002, 41, 1215.
(33) Mobian, P.; Kern, J.-M.; Sauvage, J.-P. HelV. Chim. Acta 2003, 86,
(35) Bonnet, S.; Collin, J.-P.; Gruber, N.; Sauvage, J.-P.; Schofield, E. R.
J. Chem. Soc., Dalton Trans. 2003, 4654.
4195.
(34) Laemmel, A.-C.; Collin, J.-P.; Sauvage, J.-P. C. R. Acad. Sci. Paris
2000, 3, 43.
(36) Bonnet, S.; Schofield, E. R.; Collin, J.-P.; Sauvage, J.-P. Inorg. Chem.
2004, 43, 8346.
Inorganic Chemistry, Vol. 45, No. 10, 2006 4025

Bonnet et al.
Scheme 1. Two Coordination Isomers of the Target Double-Scorpionate Molecule
Scheme 2. Synthesis of Alkylbromide Chain 4 Bearing a Benzonitrile Ligand, L1
Scheme 3. Synthesis of Alkylbromide Chain 5 Bearing a Dialkylesulfoxide Ligand, L2
In this paper, we describe the synthesis, characterization,
and photoreactivity of the two isomers of a double scorpi-
onate molecule, complexes 12+ and 22+ (Scheme 1). Notably,
the motion of the phenanthroline chelate is reported to take
place during irradiation at room temperature. Thermal
coordination of the tail is also reported, which allows one
to envision future conversion of one isomer into the other.
synthesize the bidentate chelate 3 (see Scheme 4), bearing
the two tails of the scorpionate. The syntheses of the two
alkylbromides 4 and 5 are depicted in Schemes 2 and 3,
respectively.
In the synthesis of 4, the first Williamson reaction led to
an inseparable mixture of the desired benzonitrile derivative
and the starting triethylene glycol monochlorohydrin. This
mixture was used in the mesylation and bromination steps,
and 4 could be obtained after chromatography on a 3 g scale.
In the synthesis of 5, alcohol 8 was tosylated instead of
mesylated as the latter option led to a water soluble
compound; hence it was difficult to extract. The moderate
hydrophilicity of tosylate 9 probably explains the low yield
Results
Synthesis of the 3,8-Dissymmetrically Substituted
Phenanthroline 3. A statistical Williamson reaction between
3,8-di(hydroxyphenyl)-1,10-phenanthroline and an equimolar
mixture of the two alkylbromides 4 and 5 was chosen to
4026 Inorganic Chemistry, Vol. 45, No. 10, 2006

Two-Position Ru(terpy)(phen)(L)2+ Scorpionate Complex
Scheme 4. Synthesis of the Disymmetric Phenanthroline 3 by a Statistical Approach
Scheme 5. Synthesis of the Two Coordination Isomers 12+ and 22+
of this step. The sulfoxide chain 5 was prepared on a 700
mg scale. The main starting material for the 3,8-disubstituted
1,10-phenanthroline is the symmetric 3,8-dibromo-1,10-
phenanthroline (Scheme 4).37
phenyl)-1,10-phenanthroline (compound 10).39 Symmetric
diphenol 10 was further reacted in a dissymmetric William-
son reaction using an equimolar mixture of 4 and 5, bearing
at their ends the two ligands L1 (benzonitrile) and L2
(dialkylesulfoxide). The dissymmetric Williamson reaction
yielded a mixture of three phenanthrolines: the dissymmetric
one bearing two different ligands (L1-phen-L2, compound
3) and two symmetric ones bearing two monodentate ligands
of the same kind (3′ ) L1-phen-L1 and 3′′ ) L2-phen-L2).
Separation of this mixture by chromatography and isolation
This symmetric molecule was turned into 3,8-dianisyl-
1,10-phenanthroline using standard Suzuki cross-coupling
conditions.38 Methoxy groups were efficiently removed in
refluxing pyridinium chloride to produce 3,8-di(parahydroxy-
(37) Saitoh, Y.; Koizumi, T.-a.; Osakada, K.; Yamamoto, T. Can. J. Chem.
1997, 75, 1336.
(38) Dietrich-Buchecker, C.; Jimenez, M. C.; Sauvage, J.-P. Tetrahedron
Lett. 1999, 40, 3395.
(39) Dietrich-Buchecker, C.; Sauvage, J.-P. Tetrahedron Lett. 1983, 24,
5091.
Inorganic Chemistry, Vol. 45, No. 10, 2006 4027

Bonnet et al.
Figure 2. UV-vis spectra of 12+ (blue) and 22+ (violet) in acetone.
of the dissymmetric product was possible because of the
higher polarity of the sulfoxide chain compared to the
benzonitrile chain. The 40% isolated yield of 3 was close to
the maximum theoretical value (50%). Compound 3 was
prepared on a 200 mg scale. It was characterized by 1H 1D
NMR, 2D COSY, ROESY, HSQC, HMBC NMR, and FAB
mass spectrometry.
Figure 3. 1H NMR spectra of 12+ and 22+ in CDCl3 (7.5 to 11 ppm)
showing the signals of the terpyridine (red) and the phenanthroline (blue).
See Scheme 1 for proton assignment.
Coordination of Phenanthroline 3 to the Ruthenium.
Because the two different monodentate ligands of bidentate
chelate 3 were located far from the coordinating nitrogen
atoms, its coordination to Ru(terpy*)Cl3 yielded a statistical
mixture of the two chloro isomers of compound Ru(terpy*)-
(3)(Cl)+, denoted 11+ and 11′+ (Scheme 5). These two
coordination isomers could not be separated at this stage.
After removal of the chloride ion by silver(I) in acetone,
the two complexes 12+ and 22+ of Scheme 1 were isolated
by chromatography.
Complexes 12+ and 22+ displayed identical mass spectra
(an m/z value of 1487.443 instead of the 1487.439 value
obtained by simulation for Ru(terpy*)(3)(PF6)+) but very
different proton NMR and UV-vis spectra.
Scheme 6. Photoinduced Opening of the Scorpion’s Tail
monodentate ligand L1 (or L2) from 12+ (or 22+) at room
temperature resulted in the “open species” Ru(terpy*)(3)-
(L)n+, where L was a solvent molecule or a chloride anion
(Scheme 6). During this process, rearrangement of the
coordination sphere, corresponding to a gliding motion (90°)
of the phen ligand around the rurhenium (II) center, might
also take place. As a result, the irradiation product was a
mixture of two isomers.
(i) The UV-vis spectra in acetone of the two complexes
1
showed a MLCT absorption maximum at 468 nm for 12+
and a shoulder around 430 nm for 22+ (Figure 2). These
values were consistent with a benzonitrile group and a
sulfoxide ligand coordinated to a Ru(terpy)(phen) core.35,36
(ii) In the proton NMR spectrum of 12+, the terpy* moiety
showed symmetric signals, which was consistent with the
diastereogenic sulfoxide ligand being far from the coordina-
tion sphere of the ruthenium; in contrast, both sides of the
terpy* moiety in 22+ were very distinctly different. This is
consistent with the sulfoxide ligand being close to the
coordination sphere of the ruthenium (Figure 3). In particular,
the protons P9 (in 12+) and P2 (in 22+) of the phenanthroline
ligand appear to be strongly shielded as a consequence of
their proximity to the terpyridine nucleus. (iii) ROESY
correlation experiments unambiguously showed the close
proximity of the protons near the ruthenium atom on the
terpy* and phen chelates and the benzonitrile ligand in 12+
and the sulfoxide ligand in 22+. This experimental evidence
clearly showed that complexes 12+ and 22+ are coordination
isomers with the benzonitrile and sulfoxide ligands, respec-
tively, coordinated to the ruthenium.
To study the photochemical isomerization process, a source
of white light filtered by interference filters centered either
at 470 nm or at 430 nm was used. These wavelengths
corresponded to the 1MLCT absorption bands of complexes
1
2+ and 22+, respectively. During the course of the reactions,
1
two H NMR probes were used: (i) the R-proton of 3 that
was on the side of the monodentate ligand (P2 and P9, see
Scheme 1) and (ii) the methyl group of the sulfoxide ligand.
The former was conclusive about the nature of the coordi-
nated monodentate ligand, the latter about the exact nature
of the isomer. They both enabled precise determination of
the number and proportions of species in solution during the
course of the photochemical reaction. The percentages of
isomerization after complete ring-opening were measured,
starting from a pure compound 12+ or 22+, on the photo-
product Ru(terpy*)(3)(L)n+. Representative results are given
Table 1.
Three main tendencies appeared from the analysis of the
1H NMR data. (i) In acetonitrile and acetone/water solutions
(entries I, II, and V), complexes 12+ and 22+ led to a statistical
mixture of the two open isomers of Ru(terpy*)(3)(L)2+. After
Photochemical Reactivity of 12+ and 22+. Irradiation
of 12+ or 22+ in Pure Form. Photoinduced expulsion of the
4028 Inorganic Chemistry, Vol. 45, No. 10, 2006

Two-Position Ru(terpy)(phen)(L)2+ Scorpionate Complex
Table 1. Photoexpulsion of the Tail and Photoisomerization of 12+ and 22+
irradiation time
(wavelength)
entry
complex
solvent system
L
yielda (%)
% isomerization
I
II
III
IV
V
12+
12+
12+
12+
22+
22+
CD3CN
CD3CN
D2O
Cl-
0.5 h (470 nm)
3 h (470 nm)
3 h (470 nm)
3 h (470 nm)
3 h (430 nm)
3 h (430 nm)
100
95
100
100
96
40
39
14
5
43
9
CD3COCD3/20% D2O
+
CD3COCD3/4% D2O + Cl-,N(C2H5)4
+
CD2Cl2/Cl-,N(C2H5)4
Cl-
CD3COCD3/20% D2O
D2O
CD2Cl2/Cl-,N(C2H5)4
Cl-
100
+
VI
a Calculated as the number of moles of both isomers of the photoproduct Ru(terpy*)(3)(L)n+ divided by the number of moles of irradiated complex.
Scheme 7. Thermal Coordination of the Scorpions’ Tails in the Open Isomers of Ru(terpy*)(3)(L)n+
Table 2. Thermal Back-Coordination of the Tail
the total disappearance of the starting product, further
ratio
irradiation led to an increase of the percentage of isomer-
starting
L in
1
2+/22+ scorpionate
ization until a statistical distribution (50:50) was reached.
(ii) In chlorination conditions (entries III, IV, and VI) the
ring-opening process took place with negligible isomeriza-
tion, leading to the open isomer Ru(terpy*)(3)(Cl)+ (com-
pounds 11+ or 11′+) where the chloride was on the same
side as the original monodentate ligand. After the total
disappearance of the starting product, further irradiation did
not lead to an increase of the percentage of isomerization.
(iii) In all cases, the photochemical product without isomer-
ization was produced faster than the photochemical product
with isomerization. Unfortunately, direct production of 22+
after irradiation of 12+, or vice-versa, was never detected. It
is noteworthy that the absence of isomerization during
chlorination experiments (entries IV and VI in Table 1)
permitted independent 1H NMR characterization of the two
chloro isomers 11+ and 11′+.
Irradiation of a Mixture of 12+ and 22+. The following
photochemical and thermal sequence of reactions was
repeated several times on the same sample to test the
efficiency of the selective irradiations: (i) 1 h of band-pass
irradiation at 470 nm in acetone/water, (ii) addition of NEt4-
Cl into the irradiation vessel and stirring 24 h at room
temperature in the dark and isolation of the resulting
complexes, and (iii) 2 h of reflux in acetone with AgBF4
and isolation of the resulting complexes. Because the
replacement of the coordinated solvent (acetone or water)
by Cl- and the thermal coordination of the tails on the
ruthenium chloride species are quantitative processes, (vide
infra) these experiments should allow us to determine if
selective irradiation favors the formation of one isomer with
respect to the other. The 12+/22+ ratios after step 3, starting
from a pure sample of 12+, were measured by 1H NMR, and
the following results were obtained: 62:38 ratio after run 1
and a 44:56 ratio after run 2.
A/B ratio Ru(terpy*)(3)(L)n+
conditions
X′/Y′
yield (%)a
60:40
95:5
D2O
Cl-
acetone 2 h reflux 60:40
60
100
AgBF4 (excess)
acetone 2 h reflux
95:5
40:60
8:92
D2O
Cl-
acetone 2 h reflux 40:60
60
100
AgBF4 (excess)
acetone 2h reflux
8:92
a Calculated by dividing the sum of the numbers of moles of 12+ and
2
2+ by the total number of moles of all Ru(terpy*)(3)(L)n+ species detected
1
by H NMR.
respectively; see Scheme 7) from a mixture of the two open
isomers of Ru(terpy*)(3)(L)n+.
Back-coordination of the scorpion’s tail was too slow at
room temperature to take place during irradiation. Irradiation
of the mixture at 40 °C did not give better results. An X/Y
mixture of the two isomers of Ru(terpy*)(3)(L)n+ generated
photochemically was heated in the dark, yielding a X′/Y′
mixture of the closed scorpionates 12+ and 22+. Within the
experimental uncertainty of 1H NMR analysis, there was no
change of the isomer ratio in thermal conditions (X′ ) X
and Y′ ) Y). The yields and final 12+/22+ compositions are
given in Table 2. No thermal reaction takes place in CH3-
CN, probably because the acetonitrile ligand is so strongly
bound to the ruthenium(II) center that it cannot be displaced
by Cl-, L1, or L2.
Discussion
Ruthenium chemistry is known to be controlled by
kinetics, and because of their polydentate nature, the ter-
dentate and bidentate chelates in Ru(terpy)(phen)(L)n+
complexes are strongly bound to the ruthenium atom. No
detectable Ru(II)-dialkylesulfoxide linkage isomerization was
observed for the monodentate ligand under the experimental
conditions used. In previous works, such an isomerization
process required particular media, such as DMSO solution,
ionic liquid, or polymer films.40-42 In addition, other
published works were consistent with the hypothesis of a
Thermal Coordination of the Scorpion’s Tail. This
reaction yielded the corresponding mixture of the initially
irradiated product (12+ or 22+) and its isomer (22+ or 12+,
Inorganic Chemistry, Vol. 45, No. 10, 2006 4029

Bonnet et al.
L ) Cl-, the use of silver salts enabled trapping of the
chloride ion. As a result, coordination of the tail was fast
and quantitative. In all cases, no significant changes in the
isomer ratios were detected after thermal back-coordination.
As a consequence, one cannot exclude the hypothesis of an
associative mechanism for such intramolecular thermal
reactions.
Scheme 8. Proposed Mechanism for the Photoinduced Isomerization
To take advantage of the efficiency of both photoinduced
isomerization in acetone/water and thermal back-coordination
from L ) chloride, we designed a sequence where (i) the
tail was photoexpelled and replaced by water with isomer-
ization, (ii) the water was replaced by chloride at room
temperature, yielding a mixture of 11+ and 11′+, and (iii)
chloride was trapped by silver(I) in acetone, leading to back-
coordination of the tail. Repeating these three steps on the
same sample allowed us to gradually enrich an initially pure
sample of 12+ in 22+. After two runs, starting from a mixture
of 12+ and 22+, a 44:56 ratio was obtained, which was beyond
the theoretical 50:50 statistical limit. This experiment proves
that the second irradiation with an interference filter centered
at 470 nm was selective on isomer 12+ and left 22+
untouched. However, the inherent experimental complexity
of this photochemical sequence (3 precipitations) obviously
limited the potential of the herein described scorpionate
molecule as a photochemically controlled molecular switch.
The long and flexible nature of the polyether chain may be
a limiting factor for the back-coordination of the tail.
dissociative mechanism for the photosubstitution reaction of
L in Ru(terpy*)(phen)(L)2+ complexes.34,36,43,44 Isomerization
of 3 was supposed to occur on the photochemically produced
pentacoordinated species (see Scheme 8). The longer such
pentacoordinated species last in solution, the higher the
isomerization percentage should be in the reaction. When
the nonhindering and symmetric nature of phenanthroline 3
close to the ruthenium center is considered, a long-lived
unsaturated intermediate would lead to a 1:1 statistical
composition of both isomers of the photoproduct Ru(terpy*)-
(3)(L)n+. In this hypothesis, the kinetics for the coordination
of an entering ligand, L, to the pentacoordinated species is
critical for the degree of isomerization after irradiation. If
coordination of L is slow compared to the isomerization
process (Scheme 8), this latter reaction will take place
preferentially. Thus, a 1:1 mixture of the final isomers (A
and B of Figure 7) will be obtained. This was probably the
case in weakly coordinating solvents (Table 1, entries II and
V). In contrast, if the coordination step leading to the
6-coordinated complex is fast versus isomerization, isomer-
ization will not be favored. The chlorination reactions (Table
1, entries IV and VI) fit well with this interpretation.
The interconversion between 12+ and 22+ would require
the tail of the scorpion to come back thermally. As such a
process did not take place spontaneously during band-pass
irradiation at room temperature, the thermal reaction was
tested in the dark (Table 2). With L ) D2O, the tail slowly
came back to coordinate the ruthenium center in wet acetone.
The moderate yield of this reaction prevented a second
irradiation of the same sample. Because the acetone was wet,
catalytic processes involving Ru(terpy*)(3)(H2O)2+ are sus-
pected to be responsible for secondary reactions.45-48 With
Conclusion
Two ruthenium(II) polypyridyl complexes, 12+ and 22+,
were synthesized and fully characterized by absorption
1
spectroscopy, mass spectrometry, and H and 13C nuclear
magnetic resonance. Their scorpionate nature was demon-
strated, and they were shown to be coordination isomers.
Because of the different natures of their coordinated mono-
dentate ligands, their 1MLCT absorption bands were different
enough to show selective irradiation by wavelength selection.
Photoinduced expulsion of the coordinated tail led to two
processes: (i) opening of the ruthena-macrocycle and
coordination of a solvent molecule, S, to the ruthenium and
(ii) isomerization of the complex, corresponding to a 90°
rotation of the phenanthroline in its plane and around the
ruthenium atom, occurring on the transient pentacoordinated
species. These two processes were studied in different
solvents showing either strong or poor coordinating proper-
ties. Photoinduced opening of the ruthena-macrocycle was
shown to be quantitative, but isomerization was a slower
process. Thermal back-coordination of the tail was investi-
gated in the dark; it was not followed by further rotation of
the bidentate chelate. With water as the monodentate ligand,
isomerization was efficient and led to a statistical mixture
of the two open isomers of Ru(terpy*)(3)(H2O)2+; however,
thermal recoordination had a low yield. In contrast, with
chloride as the monodentate ligand, isomerization did not
take place during irradiation but back-coordination was
quantitative. It was experimentally shown that band-pass
filters permitted selective irradiation of one isomer in a
(40) Smith, M. K.; Gibson, J. A.; Young, C. G.; Broomhead, J. A.; Junk,
P. C.; Keene, F. R. Eur. J. Inorg. Chem. 2000, 1365.
(41) Rack, J. J.; Winkler, J. R.; Gray, H. B. J. Am. Chem. Soc. 2001, 123,
2432.
(42) Rack, J. J.; Rachford, A. A.; Shelker, A. M. Inorg. Chem. 2003, 42,
7357.
(43) Hecker, C. R.; Fanwick, P. E.; McMillin, D. R. Inorg. Chem. 1991,
30, 659.
(44) Adamson, A. W.; Feischauer, P. D. Concepts of Inorganic Photo-
chemistry; Wiley: New York, 1975.
(45) Gerli, A.; Reedijk, J.; Lakin, M. T.; Spek, A. L. Inorg. Chem. 1995,
34, 1836.
(46) Moyer, B. A.; Thompson, M. S.; Meyer, T. J. J. Am. Chem. Soc. 1980,
102, 2310.
(47) Thompson, M. S.; Meyer, T. J. J. Am. Chem. Soc. 1982, 104, 4106.
(48) Thompson, M. S.; Meyer, T. J. J. Am. Chem. Soc. 1982, 104, 5070.
4030 Inorganic Chemistry, Vol. 45, No. 10, 2006

Two-Position Ru(terpy)(phen)(L)2+ Scorpionate Complex
mixture of 12+ and 22+. This led to partial enrichment of the
mixture of the nonirradiated isomer.
containing 0.80 mL of mesyl chloride in 20 mL of dry dichlo-
romethane was added dropwise at 0 °C within 20 min. The solution
was stirred at 1 °C for 4 h and at room temperature overnight.
Fifty milliliters of water was added at 0 °C under vigorous stirring.
The aqueous phase was extracted with dichloromethane, and the
combined organic phases were washed with water and brine, dried
on Na2SO4, and evaporated under vacuum. Yield: 1.57 g of a
yellowish oil. NMR analysis showed the presence of the chloro-
mesyltriethyleneglycol. This mesylate mixture was dissolved in 20
mL of acetone and transferred into a solution of 3.85 g (44.3 mmol)
of lithium bromide in 100 mL of acetone. The solution was refluxed
under argon for 4 h. The acetone was removed under vacuum, water
and DCM were added, and the aqueous phase was extracted with
dichloromethane. The combined organic phases were washed with
water and brine and evaporated to dryness. The crude product was
chromatographed on silica gel (eluent DCM/MeOH 0.5%). The
bromochlorotriethyleneglycol was removed to yield 736 mg of the
Experimental Section
1H NMR spectra were acquired on a Brucker AVANCE 300
(300 MHz) a Bruker AVANCE 400 (400 MHz), or a Bruker
AVANCE 500 (500 MHz) spectrometer, using the deuterated
solvent as the lock and the residual solvent as the internal reference.
Mass spectra were obtained by using a VG ZAB-HF(FAB)
spectrometer, a VG-BIOQ triple quadrupole, positive mode, or a
Bruker MicroTOF spectrometer (ES-MS). UV-vis spectra were
recorded with a Kontron Instruments UVIKON 860 spectrometer
at room temperature.
4′-(2,5-Ditertiobutylphenyl)-2,2′;6′,2′′-terpyridine (terpy*),49 tri-
ethyleneglycol monoiodide (3,6-dioxa-1-hydroxy-8-iodooctane),50
and 3,8-dianisyl-1,10-phenanthroline51 were prepared according to
literature procedures. Tetraethylammonium chloride was dried
overnight under vacuum. 1,10-Phenanthroline hydrochloride, ac-
etonitrile, 2-(2-(2-chloroethoxy)ethoxy)ethanol, 2-methylthioethanol,
and parahydroxybenzonitrile were commercial products. RuCl3‚
xH2O was kindly provided by Johnson Matthey Inc. Dichlo-
romethane was distilled under CaH2. Acetone was distilled and dried
over sodium sulfate. KPF6 was used as a 40 g/L aqueous solution,
and KNO3 was used as a saturated aqueous solution. In every
synthesis of ruthenium complexes, chromatography fractions were
worked up as follows: addition of an excess of KPF6, evaporation
of acetone until precipitation, filtration, washing with water,
recovery from the P4 frit with acetone, and drying under vacuum.
2-(2-(2-Paracyanophenylethoxy)ethoxy)ethanol. A suspension
of 11.3 g of cesium carbonate (34.8 mmol) in 75 mL of
dimethylformamide was put under argon; 2.07 g of parahydroxy-
benzonitrile (17.4 mmol) in 25 mL of DMF was added dropwise
without a noticeable color change. The suspension was heated at
60 °C, and a solution containing 5.86 g of 2-(2-(2-ethoxy)ethoxy)-
chloroethanol (34.8 mmol) in 25 mL of DMF was added dropwise
under argon. The reaction vessel was stirred under argon at 60 °C
overnight (18 h), and the DMF was removed under vacuum. Water
and DCM were added, and the aqueous phase was extracted three
times with dichloromethane. The organic phases were combined,
washed with NaOH (0.1 M), water, and brine, and evaporated to
dryness to yield 6.56 g of crude oil. This material was put on a
silica gel chromatography column using DCM/MeOH (2%) as the
eluent. The main fraction was collected; the solvent evaporated,
and the residue was weighed (5.69 g). NMR analysis revealed that
the oil was a mixture of the product and the starting chlorotrieth-
yleneglycol. TLC (silica, alumina) showed that these two com-
pounds could not be separated by chromatography. The sample was
1
analytically pure bromide 4 (76% from the starting alcohol). H
NMR (300 MHz, CDCl3): δ 7.51 (d, 2H, a, J ) 9.1 Hz), 6.92 (d,
2H, b, J ) 8.9 Hz), 4.12 (t, 2H, ú, J ) 4.7 Hz), 3.83 (t, 2H, ꢀ, J
) 4.9 Hz), 3.75 (t, 2H, â, J ) 6.2 Hz), 3.70-3.60 (m, 4H, γδ),
3.41 (t, 2H, R, J ) 6.2 Hz). 13C NMR (300 MHz CDCl3): δ 162.1
(c), 133.9 (a), 119.2 (d), 115.4 (b), 104.0 (CN), 71.2, 70.8, 70.6,
70.5, 69.4 (âγδꢀ), 67.8 (ú), 30.5 (R). IE-MS: m/z (calcd) 313.0
(313.0 [M]+), 194.9 (195.0 [M - OC6H4CN]+), 145.0 (146.1 [M
- Br(CH2CH2O)2 + H]+), 106.9 (107.0 [M - (OCH2CH2)2OC6H4-
CN]+), 102.0 (102.0 [M - Br(CH2CH2O)3]+).
Compound 6. Potassium hydroxyde (2.74 g, 48.9 mmol) was
ground in a mortar and put into a 50 mL two-necked round-bottom
flask. A condensor was adapted, and the flask was put under argon
and heated to 60 °C. 2-Methylthioethanol (4.25 mL, 48.9 mmol)
was added dropwise under efficient stirring, and the suspension
was stirred for 15 min; 16.8 g (48.9 mmol) of triethylene glycol
monoiodide was then added dropwise to ensure that the internal
temperature did not go higher than 70 °C. The reaction mixture
was stirred at 60 °C for 4 h. The mixture was cooled to room
temperature; 80 mL of water and 80 mL of dichloromethane were
added, and the aqueous phase was extracted three times with
dichloromethane. The combined organic phases were washed with
water and brine and dried over sodium sulfate; the solvent was
removed under vacuum. The crude mixture (14.4 g) was put in an
alumina column and eluted with a DCM/hexane mixture (from 1:1
to 1:0). The starting iodo chain and the elimination product were
removed to yield the substitution product 6 as a colorless oil.
Yield: 5.65 g (38%). 1H NMR (300 MHz, CDCl3): δ 4.60 (t, 1H,
a, J ) 3.5 Hz), 3.88-3.78, 3.67-3.53, 3.52-3.42 (m, 2H, 13H
and 1H resp, R, â, γ, δ, ꢀ, ú, η, e), 2.66 (t, 2H, θ, J ) 6.9 Hz),
2.11 (s, 3H, CH3(SO)), 1.90-1.40 (m, 6H, b, c, d). 13C NMR (300
MHz, CDCl3): δ 99.0 (a), 70.7-70.5 (γδꢀú), 70.4 (η), 66.7 (R),
62.3 (â), 53.5 (e), 33.5 (θ), 30.7, 25.5, 19.6 (b, c, d), 16.1 (CH3-
(SO)). IE-MS: m/z (calcd) 307.1 (308.1 [M - H]+), 233.1 (233.1
[M - CH3SCH2CH2]+), 225.1 (225.1 [M - THP + 2H]+), 206.0
(206.1 [M - THPOH]+), 119.1 (119.1 [M - THPO(CH2CH2O)2]+),
92.0 (92.1 [M - THP(OCH2CH2)3 + H]+), 85.1 (85.1 [M -
CH3S(CH2CH2O)4]+), 75.1 (75.1 [M - THPO(CH2CH2O)4]+).
1
used for the next step without further purification. H NMR (300
MHz, CDCl3): δ 7.54 (d, 2H, a, J ) 8.9 Hz), 6.94 (d, 2H, b, J )
9.0 Hz), 4.15 (t, 2H, R, J ) 4.6 Hz), 3.85 (t, 2H, â, J ) 4.8 Hz),
3.75-3.56 (m, 8H, γδꢀú), 2.53 (s, 1H, OH). 13C NMR (300 MHz,
CDCl3): δ 162.1 (c), 134.0 (a), 119.2 (d), 115.4 (b), 104.2 (CN),
72.6-69.4 (âγδꢀ), 67.7 (ú), 61.7 (R).
Compound 4. The preceding mixture of alcohols (1.01 g) was
dissolved in 50 mL of dichloromethane and cooled to 0 °C under
argon; 10 mL of distilled triethylamine was added. A solution
Compound 7. Thioether 6 (752 mg, 2.44 mmol) was dissolved
under argon in 75 mL of dichloromethane, and the mixture was
cooled to 0 °C; 504 mg of m-chloroperbenzoic acid (75% pure with
25% of m-chlorobenzoic acid, 2.44 mmol) was dissolved in 50 mL
of dichloromethane. This solution was added dropwise to the
thioether solution at 0 °C, and the mixture was stirred at 0 °C for
8 h under argon. The solution was quenched with 50 mL of
saturated aqueous sodium carbonate without letting the temperature
(49) Collin, J.-P.; Dixon, I. M.; Sauvage, J.-P.; Williams, J. A. G.;
Barigelletti, F.; Flamigni, L. J. Am. Chem. Soc. 1999, 121, 5009.
(50) Koizumi, M.; Dietrich-Buchecker, C.; Sauvage, J.-P. Eur. J. Org.
Chem. 2004, 770.
(51) (a) Dietrich-Buchecker, C.; Jime´nez-Molero, M. C.; Sauvage, J.-P.
Tetrahedron Lett. 1999, 3395. (b) Colasson, B. Ph.D. Thesis, Uni-
versite´ Louis Pasteur, Strasbourg, France, 2003.
Inorganic Chemistry, Vol. 45, No. 10, 2006 4031

Bonnet et al.
go over 15 °C. The mixture was extracted three times with
dichloromethane; the combined organic phases were washed with
brine, dried on sodium sulfate, and evaporated. The crude product
was put on an alumina column, and the remaining starting material
was removed with DCM/MeOH (0.5%) The sulfoxide was eluted
with DCM/MeOH (1%). Yield: 746 mg of sulfoxide 7 (94%). 1H
NMR (300 MHz, CDCl3): δ 4.63 (dd, 1H, a, J ) 2.8, 4.2 Hz),
3.95-3.80, 3.70-3.55, 3.55-3.45 (m, 4H, 11H and 1H resp,
Râγδꢀú, e), 3.05-2.85 (m, 2H, θ), 2.64 (s, 3H, CH3(SO)), 1.90-
1.45 (m, 8H, b + c + d). 13C NMR (300 MHz, CDCl3): δ 99.1
(a), 70.7-70.5 (γδꢀú), 66.7 (R), 63.7 (η), 62.4 (â), 54.9 (θ), 53.4
(e), 39.3 (CH3(SO)), 30.7, 25.5, 19.6 (b, c, d). IE-MS: m/z (calcd)
325.2 (325.2 [M + H]+), 307.3 (307.3 [M - OH]+), 295.2 (295.1
[M - CH3O + 2H]+), 241.2 (241.1 [M - THP + 2H]+), 197.1
(197.1 [M - THPOCH2CH2 + 2H]+), 153.1 (153.0 [M - THP-
(OCH2CH2)2 + 2H]+), 85.1 (85.1, [M - CH3S(CH2CH2O)4]+), 63.1
(63.0 [M - THP(OCH2CH2)4]+).
Compound 10. Forty-four milliliters of 37% hydrochloric acid
was slowly added to 40 mL of pyridine in a three-necked 100 mL
round-bottom flask. A distillation apparatus was adapted, and the
water was distilled off under argon until the internal temperature
in the flask reached 220 °C. The pyridinium chloride was cooled
to 140 °C, and 1.00 g (2.56 mmol) of 3,8-dianisylphenanthroline
was added as a solid under argon. The mixture was heated at reflux
(221 °C) for 3 h. The heating was stopped when the temperature
was 140 °C and 100 mL of water was slowly added. The reaction
mixture was homogenized and transferred into a 500 mL Erlen-
meyer flask with 200 mL of water and 100 mL of ethanol. The
yellow suspension was neutralized with 0.1 M sodium hydroxide
solution until the pH of the liquid phase was stable (7.5). The solid
was filtered off using a Millipore filter and dried under vacuum
1
using P2O5 as a drying agent. Yield: 933 mg (100%). H NMR
(300 MHz, DMSO-d6): δ 9.90 (s, 2H, PhOH), 9.38 (s, 2H, P2),
8.84 (d, 2H, P4, J ) 2.2 Hz), 8.11 (s, 2H, P5), 7.83 (d, 4H, Pa, 8.8
Hz), 6.99 (d, 4H, Pb, J ) 8.8 Hz). 13C NMR (500 MHz, DMSO-d6,
assignments were done according to HSQC and HMBC correlation
experiments): δ 158.0 (Pc), 146.6 (P2), 140.7 (P6), 134.7 (P3), 133.1
(P4), 128.3 (Pa), 127.0 (P5), 126.2 (Pd), 116.0 (Pb). P7 could not be
assigned. Anal. Calcd for C24H16N2O2‚HCl‚2H2O: C, 65.98; H,
4.84; N, 6.41. Found: C, 65.49; H, 4.82; N, 6.24.
Compound 8. Protected alcohol 7 (725 mg, 2.24 mmol) was
dissolved in 250 mL of ethanol; a catalytic amount of p-
toluenesulfonic acid was added, and the solution was refluxed under
argon for 5 h. The solvent was evaporated to dryness, and the yield
1
was 533 mg of analytically pure 8 (99%). H NMR (300 MHz,
CDCl3): δ 3.92 (m, 2H, R), 3.71 (t, 2H, â), 3.66 (s, 8H, γδꢀú),
3.59 (t, 2H, η), 3.06-2.84 (m, 2H, θ), 2.63 (s, 3H, CH3(SO)), 2.50
(broad s, 1H, OH). 13C NMR (300 MHz, CDCl3): δ 72.5 (R), 70.6-
70.3 (γδꢀú), 63.6 (η), 61.6 (â), 54.7 (θ), 39.1 (CH3(SO)). FAB-
MS: m/z (calcd) 241.2 (240.1 [M + H]+).
Compound 3. 3,8-Di(parahydroxyphenyl)-1,10-phenanthroline
(20 mg, 55 µmol) was dissolved in 10 mL of DMF. The solution
was put under argon, and 89 mg of cesium carbonate (275 µmol)
was added; in less than two minutes, the yellow solution turned
bright orange. A solution containing 36 mg of 4 (110 µmol) and
34 mg of 5 (110 µmol) in 12 mL of DMF was prepared and added
to the phenolate solution. A condensor was adapted, and the reaction
mixture was degassed and heated at 60 °C under argon for 24 h.
The DMF was pumped under vacuum; water and dichloromethane
were added, and the aqueous phase was extracted three times with
DCM. The organic phases were combined, washed with water and
brine, and evaporated to dryness. This crude material was put on a
neutral alumina column and eluted with DCM/MeOH (1%). The
positions of the three phenanthrolines in the column were followed
with a UV lamp, and the three compounds were collected separately.
Yield: 18 mg of 3 (44%) and 9 mg of each of the two symmetric
Compound 9. Alcohol 8 (516 mg, 2.15 mmol) and p-toluene-
sulfonyl chloride (744 mg, 3.90 mmol) were dissolved in 80 mL
of distilled dichloromethane. The solution was put under argon and
cooled to 0 °C. Four milliliters of triethylamine (28.9 mmol) was
added at 0 °C; the solution was stirred at this temperature for 30
min and then at room temperature for 3 h. The reaction was
quenched by the addition of 408 mg of Na2CO3 in 30 mL of water,
and the mixture was stirred for 30 min at room temperature. Fifty
milliliters of saturated NaHCO3 was added, and the aqueous phase
was extracted three times with dichloromethane. The organic phases
were collected and evaporated, and the crude material was purified
by chromatography on alumina (eluent DCM/MeOH 1%). Yield:
206 mg of tosylate 9 (24%). 1H NMR (300 MHz, CDCl3): δ 7.77
(d, 2H, a, J ) 8.3 Hz), 7.32 (d, 2H, b, J ) 8.0 Hz), 4.13 (t, 2H, â,
J ) 4.2, 5.4 Hz), 3.88 (m, 2H, R), 3.68-3.56 (m, 10H, γδꢀúη),
3.05-2.93, 2.91-2.81 (m, 2H, θ), 2.60 (s, 3H, CH3(SO)), 2.42 (s,
3H, CH3(Ts)). 13C NMR (300 MHz, CDCl3): δ 144.9 (d), 133.0
(c), 129.9 (a), 128.0 (b), 70.8, 70.7, 70.6, 70.5 (γδꢀú), 69.3 (R),
68.8 (â), 63.7 (η), 54.9 (θ), 39.3 (CH3(SO)), 21.7 (CH3(Ts)).
1
phenanthrolines 3′ and 3′′. Characterization of 3. H NMR (400
MHz, CDCl3): δ 9.38 (s, 2H, P2 + P9), 8.32 (d + d, 2H, P4 + P7),
7.84 (s, 2H, P5 + P6), 7.70 (d + d, 4H, Pa3 + Pa8), 7.54 (d, 2H, Pa,
J ) 8.9 Hz), 7.08 (d + d, 4H, Pb3 + Pb8), 6.95 (d, 2H, Pb, J ) 8.9
Hz), 4.23-4.15 (m, 6H, R3 + R8 + ú3), 3.92-3.87 (m, 8H, â3 +
â8 + ꢀ3 + η8), 3.76-3.66 (m, 12H, γ3 + δ3 + γ8 + δ8 + ꢀ8 + ú8),
3.03-2.83 (m, 2H, θ8), 2.61 (s, 3H, CH3(SO)). 13C NMR (400 MHz,
CDCl3, assigments were made according to HSQC and HMBC 2D
1H-13C HETCORR experiments): δ 162.2 (Pc), 159.34, 159.30
(Pc3, Pc8), 149.35 (P2 + P9), 144.8 (P11 + P12), 135.3 (Pd3 + Pd8),
134.1 (Pa), 132.7 (P4 + P7), 130.3 (P3 + P8), 128.7 (Pa3 + Pa8),
128.5 (P13 + P14), 127.2, 127.1 (P5, P6), 119.3 (PCN), 115.5, 115.4
(Pb, Pb3 + Pb8), 104.2 (Pd), 71.1, 71.0, 71.0, 70.8, 70.6 (γ3 + γ8 +
δ3 + δ8 + ꢀ8 + ú8), 69.9, 69.8 (â3 + â8), 69.6 (ꢀ3), 67.9 (ú3), 67.7,
67.7 (R3 + R8), 63.7 (η8), 54.9 (θ8), 39.3 (CH3(SO)). FAB MS:
m/z (calcd) 820.2 (820.3 [M + H]+).
Complex 11+‚PF6-. Seventeen milligrams of Ru(terpy*)Cl3 (27
µmol) and 5 mg of lithium chloride (27 µmol) were weighed in a
50 mL two-necked round-bottom flask; 5 mL of water and 10 mL
of ethanol were added, and the suspension was put under argon.
Eighteen milligrams of phenanthroline 3 (22 µmol) was dissolved
in 10 mL of hot ethanol, and this solution was transferred to the
reaction vessel. The mixture was degassed and heated at reflux
under argon for 5 h. Aqueous KPF6 and distilled water were added
Compound 5. Tosylate 9 (179 mg, 0.454 mmol) and lithium
bromide (395 mg, 4.54 mmol) were dissolved in 25 mL of acetone,
and the mixture was refluxed under argon for 4 h. The acetone
was evaporated, and the crude product was purified by chroma-
tography on silica (eluent DCM/MeOH 5%). Yield: 105 mg of
bromide 5 (76%). 1H NMR (300 MHz, CDCl3): δ 3.92-3.88 (m,
2H, η), 3.80 (t, 2H, â, J ) 6.3 Hz), 3.65 (broad s, 8H, γδꢀú), 3.46
(t, 2H, R, J ) 6.3 Hz), 3.00-2.85 (m, 2H, θ), 2.63 (s, 3H, CH3-
(SO)). 13C NMR (300 MHz, CDCl3): δ 71.3 (â), 70.8 (γ), 70.7
(δ), 70.7 (ꢀ), 70.6 (ú), 63.7 (η), 55.0 (θ), 39.4 (CH3(SO)), 30.5
(R). IE-MS: m/z (calcd) 303.1 (303.0 [M + H]+), 223.0 (223.1 [M
- Br]+), 196.0 (195.0 [M - CH3SOCH2CH2O]+), 179.1 (179.0
[M - BrCH2CH2O]+), 151.0 (151.0 [M - CH3SO(CH2CH2O)2]+),
135.1 (135.1 [M - Br(CH2CH2O)2]+), 107.0 (107.0 [M - CH3-
SO(CH2CH2O)3]+), 91.1 (91.1 [M - Br(CH2CH2O)3]+), 63.1 (63.1
[M - BrCH2CH2(OCH2CH2)3]+).
4032 Inorganic Chemistry, Vol. 45, No. 10, 2006

Two-Position Ru(terpy)(phen)(L)2+ Scorpionate Complex
to the cooled solution; the ethanol was removed under vacuum,
and the violet precipitate was filtered on a P4 frit and washed with
water. The solid was recovered with acetone and evaporated to
dryness. The mixture of chloro isomers was put on a silica gel
column and eluted with an acetone/water/saturated KNO3(aq) mixture
(300:15:2). The violet band was collected, precipitated with KPF6
and water, filtered, washed with water, recovered with acetone, and
evaporated to dryness. Yield: 22 mg of a 1:1 mixture of the two
isomers [11][PF6]. UV-vis (CHCl3): λmax (ꢀ) 367.5 (33 800), 516.5
nm (11 000 M-1 cm-1). ES MS: m/z (calcd) 1377.449 (1377.444
[M - PF6]+).
was transferred into the flask, the reaction mixture was degassed
and refluxed under argon in the dark for 2 h. The silver chloride
precipitate was removed by filtration on Celite, the complexes were
precipitated by the addition of KPF6 and water, filtered, washed
with water, recovered with acetone, and dried under vacuum. The
crude material was put on a fine silica gel column and eluted with
an acetone/water/saturated KNO3 mixture 300:6:1. The yellow band
was collected, precipitated with KPF6, filtered, washed with water,
recovered with acetone, and dried to give 12 mg of [2][PF6]2. The
polarity of the eluent was increased to 75:6:1, and the orange band
on the column was collected, precipitated with KPF6, filtered,
washed with water, recovered with acetone and evaporated to
dryness to yield 12 mg of [1][PF6]2.
Preparation and Characterization of Isomer 11+. Three
milligrams of [1][PF6]2 (1.8 µmol) was weighed in a conical flask;
3 mg (18 µmol) of dry tetraethylammonium chloride was added,
and an NMR tube was prepared using CD2Cl2 as the solvent. The
tube was irradiated for 2 h at 25 °C with a xenon 1000 W lamp
fitted with a water filter and an Andover 470FS10-50 interference
filter. The color of the solution changed from orange to violet. The
solution was transferred into a flask containing 30 mL of saturated
KPF6 aqueous solution, and the ruthenium complex precipitated.
It was filtered, washed thoroughly with water, recovered with
acetone, and vacuum dried. Yield: 2.8 mg (100%) of [11][PF6] as
Characterization of 12+‚2PF6-. H NMR (500 MHz, acetone-
1
d6): δ 10.23 (d, 1H, P2, J ) 1.9 Hz), 9.25 (d, 1H, P4, J ) 2.0 Hz),
9.24 (s, 2H, T3′5′), 8.89 (m, 2H, J ) 8.9, 2.5, 1.3 Hz), 8.52 (d, 1H,
P5, J ) 8.9 Hz), 8.33 (d, 1H, P6, J ) 9.0 Hz), 8.15-8.12 (m, 4H,
T66′′ + T44′′), 8.10 (d, 2H, To, J ) 1.7 Hz), 8.03 (d, 1H, P9), 8.02
(d, 2H, Pa3, J ) 6.6 Hz), 7.82 (t, 1H, Tp, J ) 1.7 Hz), 7.80 (d, 2H,
BNa, J ) 9.1 Hz), 7.41 (m, 4H, T55′′ + Pa8), 7.21 (d, 2H, BNb, J )
9.1 Hz), 7.21 (d, 2H, Pb3, J ) 8.9 Hz), 6.95 (d, 2H, Pb8, J ) 8.9
Hz), 4.39 (m, 2H, ê3, J ) 4.5 Hz), 4.35 (t, 2H, R3, J ) 5.3 Hz),
4.13 (t, 2H, R8, J ) 4.7 Hz), 3.83-3.79 (m, 8H, η8 + ꢀ3 + â3 +
â8), 3.66-3.55 (m, 12H, γ3 + δ3 + γ8 + δ8 + ꢀ8 + ê8), 2.97-
2.90 (m, 1H, θ′′8), 2.82-2.74 (m, 1H, θ′8), 2.50 (s, 3H, CH3(SO)),
1.51 (s, 18H, tBu). 13C NMR (500 MHz, acetone-d6, assigments
were made according to HSQC and HMBC 2D 1H-13C HETCORR
experiments): δ 164.0 (BNc), 160.2 (Pc3), 160.0 (Pc8), 158.5 (T22′′),
157.7 (T2′6′), 154.1(T66′′), 151.3 (P2), 151.1 (T4′), 149.5 (P9), 146.3
(P8), 145.3 (P3), 138.6 (T44′′), 136.6 (Ti), 135.4 (BNa), 133.2 (P7),
133.2 (P14), 132.4 (P13), 132.3 (P4), 131 (P11), 130.3 (P12), 129.3
(Pa3), 128.8 (P5), 128.7 (Pd3), 128.4 (Pa8), 128.4 (T55′′), 128.0 (P6),
127.5 (Pd8), 126.3 (BNd), 124.7 (T33′′), 124.5 (Tp), 122.3 (To), 122.2
(Tm), 122.0 (T3′5′), 116.2 (Pb3), 116.2 (BNb), 115.3 (Pb8), 101.2 (CN),
69 (â3 - ꢀ3), 69 (â8 - ú8), 68.5 (ú3), 68 (R3), 67.6 (R8), 64.3 (η8),
53.9 (θ3), 38.4 (CH3(SO)), 35.0 (C(Me3)), 30.8 (Me3). ES-MS: m/z
(calcd) 1487.42 (1487.44 [M - PF6]+), 671.231 (671.238 [M -
2PF6]2+). UV-vis (acetone): λmax (ꢀ) 362 nm (23 300), 468 nm
(9090 L mol-1 cm-1).
1
a 95:5 mixture of the two isomers 11+/11′+. H NMR (400 MHz,
CD2Cl2): δ 10.77 (d, 1H, P2, J ) 1.9 Hz), 8.89 (d, 1H, P4, J ) 2.0
Hz), 8.63 (s, 2H, T3′5′), 8.49 (d, 2H, T33′′, J ) 8.0 Hz), 8.34-8.32
(m, 2H, P5 + P7), 8.13 (d, 1H, P6, J ) 9.0 Hz), 8.03 (d, 2H, Pa3,
J ) 6.7 Hz), 7.88 (td, 2H, T44′′, J ) 7.6, 1.4 Hz), 7.79 (d, 1H, P9,
J ) 1.9 Hz), 7.78 (d, 2H, To, J ) 1.9 Hz), 7.70 (t, 1H, Tp, J ) 1.7
Hz), 7.62 (m, 2H, T66′′), 7.56 (d, 2H, Pa, J ) 9.0 Hz), 7.23 (d, 2H,
Pa8, J ) 8.9 Hz), 7.21-7.17 (m, 4H, T55′′ + Pb3), 6.99 (d, 2H, Pb,
J ) 9.0 Hz), 6.93 (d, 2H, Pb8, J ) 8.8 Hz), 4.23 (m, 2H, R3), 4.18
(m, ú3), 4.08 (m, 2H, R8), 3.89 (m, 2H, â3), 3.86 (m, 2H, ꢀ3), 3.82
(m, 2H, η8), 3.77 (m, 2H, â8), 3.73 (s, 4H, γ3 + δ3), 3.64-3.62
(m, 2H, γ8), 3.60-3.58 (m, 2H, δ8), 3.58 (s, 4H, ꢀ8 + ú8), 2.96-
2.76 (m, 2H, θ8), 2.53 (s, 3H, CH3(SO)), 1.49 (s, 18H, tBu).
Preparation and Characterization of Isomer 11′+. Three
milligrams (1.8 µmol) of [2][PF6]2 was weighed in a conical flask;
3 mg (18 µmol) of dry tetraethylammonium chloride was added,
and an NMR tube was prepared using CD2Cl2 as the solvent. The
tube was irradiated for 2 h at 25 °C with a xenon 1000 W lamp
fitted with a water filter and an Andover 430FS10-50 interference
filter. The color of the solution changed from yellow to violet. The
solution was transferred into a flask containing 30 mL of saturated
KPF6 aqueous solution, and the ruthenium complex precipitated.
It was filtered, washed thoroughly with water, recovered with
acetone, and vacuum dried. Yield: 2.8 mg of [11][PF6] as a 9:91
Characterization of 22+‚2PF6-. H NMR (500 MHz, acetone-
1
d6): δ 10.84 (d, 1H, P9, J ) 1.9 Hz), 9.37 (d, 1H, T3′, J ) 1.45
Hz), 9.29 (d, 1H, P7, J ) 1.9 Hz), 9.29 (d, 1H, T5′, J ) 1.44 Hz),
8.94 (d, 1H, T3, J ) 7.7 Hz), 8.88 (d, 1H, P4, J ) 1.9 Hz), 8.84 (d,
1H, T3′′, J ) 7.8 Hz), 8.50 (d, 1H, P6, J ) 8.9 Hz), 8.32 (d, 1H, P5,
J ) 8.9 Hz), 8.31 (d, 1H, T6′′, J ) 4.9 Hz), 8.23 (td, 1H, T4, J )
7.9,1.5 Hz), 8.18-8.14 (m, 2H, T6 + T4′′), 8.10 (d, 2H, Pa8, J )
8.8 Hz), 8.09 (d, 2H, To, J ) 1.7 Hz), 7.84 (t, 1H, Tp, J ) 1.7 Hz),
7.80 (d, 1H, P2, J ) 1.9 Hz), 7.57 (d, 2H, BNa, J ) 9.0 Hz), 7.52
(ddd, 1H, T5, J ) 1.3, 5.6, 7.5 Hz), 7.47 (d, 2H, Pb8, J ) 8.9 Hz),
7.44 (ddd, 1H, T5′′), 7.39 (d, 2H, Pa3, J ) 8.9 Hz), 7.06 (d, 2H,
BNb, J ) 9.0 Hz), 6.89 (d, 2H, Pb3, J ) 8.8 Hz), 4.49 (dddd, 2H,
R8, J ) 2.1, 5.8, 13.5, 41.6 Hz), 4.22 (t, 2H, ú3, J ) 4.7 Hz), 4.11
(m, 1H, η8), 4.07 (t, 2H, R3, J ) 4.9 Hz), 4.03 (m, 1H, η′8), 3.88
(m, 2H, â3), 3.86 (m, 1H, â8), 3.83 (m, 2H, ꢀ3), 3.80 (m, 1H, â′8),
3.76 (m, 1H, θ8), 3.66 (m, 2H, γ3), 3.61 (m, 2H, ú8), 3.59 (m, 2H,
δ3), 3.59 (m, 2H, γ8), 3.57 (m, 2H, ꢀ8), 3.52 (m, 2H, δ8), 2.99 (m,
1H, θ′8), 2.63 (s, 3H, CH3(SO)), 1.50 (s, 18H, tBu). 13C NMR (500
MHz, acetone-d6, assignments were done according to HSQC and
HMBC 2D 1H-13C HETCORR experiments): δ 162.4 (BNc), 161.0
(Pc8), 160.2 (Pc3), 157.9 (T6′), 157.7 (T2′), 157.6 (T22′′), 155.1 (P9),
154.7 (T6), 154.2 (T6′′), 152.5 (Tm), 147.4 (P2), 147.1 (P8), 144.5
(P3), 140.1 (T44′′), 136.4 (T4′), 134.5 (P13), 134.4 (P4), 134.0 (BNa),
133.0 (P7), 133.0 (P14), 131.2 (P12), 130.4 (P11), 129.6 (T5′′), 129.5
1
mixture of the two isomers 11+/11′+. H NMR (400 MHz, CD2-
Cl2): δ 10.78 (d, 1H, P2, J ) 1.9 Hz), 8.90 (d, 1H, P4, J ) 2.0
Hz), 8.63 (s, 2H, T3′5′), 8.49 (d, 2H, T33′′, J ) 8.0 Hz), 8.32 (d, 1H,
P5, J ) 9.0 Hz), 8.31 (d, 1H, P7, J ) 1.8 Hz), 8.13 (d, 1H, P6, J )
9.0 Hz), 8.03 (d, 2H, Pa3, J ) 6.7 Hz), 7.88 (td, 2H, T44′′, J ) 7.6,
1.4 Hz), 7.79 (d, 1H, P9, J ) 1.9 Hz), 7.78 (d, 2H, To, J ) 1.9 Hz),
7.70 (t, 1H, Tp, J ) 1.7 Hz), 7.62 (m, 2H, T66′′), 7.51 (d, 2H, Pa,
J ) 9.0 Hz), 7.22-7.17 (m, 6H, Pa8 + T55′′ + Pb3), 6.95 (d, 2H,
Pb, J ) 9.0 Hz), 6.89 (d, 2H, Pb8, J ) 8.8 Hz), 4.25 (m, 2H, R3),
4.13 (m, ú3), 4.04 (m, 2H, R8), 3.90 (m, 2H, â3), 3.86 (m, 2H, ꢀ3),
3.82 (m, 2H, η8), 3.77 (m, 2H, â8), 3.65 (s, 4H, ꢀ8 + ú8), 3.63 (s,
4H, γ3 + δ3), 3.64-3.62 (m, 2H, γ8), 3.60-3.58 (m, 2H, δ8), 3.03-
2.80 (m, 2H, θ8), 2.57 (s, 3H, CH3(SO)), 1.48 (s, 18H, tBu).
-
12+‚2PF6 and 22+‚2PF6-. Eighteen milligrams (93 µmol) of
silver tetrafluoroborate were dissolved in 10 mL of acetone and
put under argon. A solution of 22 mg (15 µmol) of [11][PF6] as an
equimolar mixture of both isomers dissolved in 20 mL of acetone
Inorganic Chemistry, Vol. 45, No. 10, 2006 4033

Bonnet et al.
(T5), 129.0 (P6), 128.8 (Pa8), 128.6 (Pa3), 128.0 (P5), 127.9 (Pd8),
127.1 (Pd3), 126.1 (T3′′), 125.8 (T3), 124.9 (Ti), 124.9 (Tp), 123.7
(T3′), 123.3 (T5′), 122.4 (To), 118.7 (BNd), 117.4 (Pb8), 115.5 (Pb3),
115.5 (BNb), 103.5 (CN), 68.7 (R8), 68.6 (η8), 68.1 (ú3), 67.6 (R3),
54.8 (θ8), 69.3-71.1 (â3 - ꢀ3), 69.1-71.0 (â8 - ú8), 38.5 (CH3-
(SO)), 34.9 (C(Me3)), 31.0 (Me3). ES-MS: m/z (calcd) 1487.443
(1487.439 [M - PF6]+), 671.242 (671.238 [M - 2PF6]2+). UV-
vis (acetone): λmax (ꢀ) 362 (23 400), shoulder at 428 nm (8330 L
mol-1 cm-1).
430 (for 22+) or 470 nm (12+) (reference of the filters, 430FS10-
50 and 470FS10-50, respectively).
1
Characterization of Ru(terpy*)(3)(D2O)2+‚2PF6-. H NMR
(300 MHz, acetone-d6/D2O (20%)): δ 10.26 (d, 1H, P2,9), 9.17 (d,
1H, P4), 9.06 (s, 2H, T3′5′), 8.77 (d, 2H, T33′′), 8.51 (m, 1H, P7),
8.45 (d, 1H, P5), 8.23 (d, 1H, P6), 8.14 (d, 2H, Pa3), 8.01 (td, 2H,
T44′′), 7.99 (d, 2H, To), 7.94 (m, 2H, T66′′), 7.80 (d, 1H, P9), 7.71
(t, 1H, Tp), 7.62 (d, 2H, Pa), 7.36-7.19 (m, 6H, Pa8 + T55′′ + Pb3),
7.09 (d, 2H, Pb), 6.89 (d, 2H, Pb8), 4.31-3.52 (m, 12H, R3 - ú3 +
R8 - η8), 3.13-2.88 (m, 2H, θ8), 2.63 (s, 3H, CH3(SO) on the
side of D2O) or 2.59 (s, 3H, CH3(SO) opposite to D2O), 1.43 (s,
18H, tBu). UV-vis (acetone/water): λmax (ꢀ) 505 nm (7900 L mol-1
cm-1). MS ES: m/z (calcd) 671.26 (671.24 [M - 2PF6 - D2O]2+),
680.8 (681.2 [M - 2PF6]2+).
Irradiation Experiments. In a typical experiment, 3 mg of
-
-
12+‚2PF6 or 22+‚2PF6 (1.8 µmol) was weighed in a vial; the
deuterated solvent was added (CD3CN, an acetone-d6/D2O mixture
9:1, or 20 equiv of tetraethylammonium chloride in CD2Cl2), and
an NMR tube was prepared in the dark. A reference spectrum was
1
taken at t ) 0, and the course of the reaction was followed by H
Acknowledgment. We would like to thank the CNRS
and the European Commission for financial support. The
Re´gion Alsace is also gratefully acknowledged for a fellow-
ship to S.B. We also thank Johnson Matthey Inc. for a loan
of RuCl3.
NMR. Irradiations were performed under the following conditions.
The NMR tubes were fitted to a glass cell thermostated at T ) 25
°C. The lamp was a high pressure 1000 W xenon arc lamp providing
a parallel beam of white light, and the beam was filtered by a 10
cm thick water filter filled with running water at 5 °C and by an
Andover interference filter with ∆λ ) 10 nm, centered either at
IC060029P
4034 Inorganic Chemistry, Vol. 45, No. 10, 2006