Ruthenium complexes of easily accessible tridentate ligands based on the 2-aryl-4,6-bis(2-pyridyl)-s-triazine motif: Absorption spectra, luminescence properties, and redox behavior

Article abstract of DOI:10.1002/chem.200400032

A family of tridendate ligands 1a-e, based on the 2-aryl-4,6-di(2-pyridyl)- s-triazine motif, was prepared along with their hetero- and homoleptic Ru ^II complexes 2a-e ([Ru(tpy)(1a-e)]²⁺; tpy = 2,2′:6′,2″-ter-pyridine) and 3a-e ([(Ru(1a-e) ₂]²⁺), respectively. The ligands and their complexes were characterized by ¹H NMR spectroscopy, ES-MS, and elemental analysis. Single-crystal X-ray analysis of 2a and 2e demonstrated that the triazine core is nearly coplanar with the non-coordinating ring, with dihedral angles of 1.2 and 18.6°, respectively. The redox behavior and electronic absorption and luminescence properties (both at room temperature in liquid acetonitrile and at 77 K in butyronitrile rigid matrix) were investigated. Each species undergoes one oxidation process centered on the metal ion, and several (three for 2a-e and four for 3a-e) reduction processes centered on the ligand orbitals. All compounds exhibit intense absorption bands in the UV region, assigned to spin-allowed ligand-centered (LC) transitions, and moderately intense spin-allowed metal-to-ligand charge-transfer (MLCT) absorption bands in the visible region. The compounds exhibit relatively intense emissions, originating from triplet MLCT levels, both at 77 K and at room temperature. The incorporation of triazine rings and the near planarity of the noncoordinating ring increase the luminescence life-times of the complexes by lowering the energy of the ³MLCT state and creating a large energy gap to the dd state.

Full text of DOI:10.1002/chem.200400032

FULL PAPER
Ruthenium Complexes of Easily Accessible Tridentate Ligands Based on the
2-Aryl-4,6-bis(2-pyridyl)-s-triazine Motif: Absorption Spectra, Luminescence
Properties, and Redox Behavior
Matthew I. J. Polson,[a] Elaine A. Medlycott,[a] Garry S. Hanan,*[a] Larisa Mikelsons,[b]
Nick J. Taylor,[b] Masashi Watanabe,[c] Yasutaka Tanaka,[c] Frÿdÿrique Loiseau,*[d]
Rosalba Passalacqua,[d] and Sebastiano Campagna[d]
Dedicated to Professor Jean-Marie Lehn on the occasion of his 65th birthday
Abstract: A family of tridendate li-
gands 1a e, based on the 2-aryl-4,6-
di(2-pyridyl)-s-triazine motif, was pre-
pared along with their hetero- and ho-
tronic absorption and luminescence
properties (both at room temperature
in liquid acetonitrile and at 77 K in bu-
tyronitrile rigid matrix) were investi-
gated. Each species undergoes one oxi-
dation process centered on the metal
ion, and several (three for 2a e and
four for 3a e) reduction processes cen-
tered on the ligand orbitals. All com-
pounds exhibit intense absorption
bands in the UV region, assigned to
spin-allowed ligand-centered (LC)
transitions, and moderately intense
spin-allowed metal-to-ligand charge-
transfer (MLCT) absorption bands in
the visible region. The compounds ex-
hibit relatively intense emissions, origi-
nating from triplet MLCT levels, both
at 77 K and at room temperature. The
incorporation of triazine rings and the
near planarity of the noncoordinating
ring increase the luminescence life-
times of the complexes by lowering the
moleptic
RuII
complexes
tpy=2,2’:6’,2’’-ter-
2a e
([Ru(tpy)(1a e)]2+
;
pyridine) and 3a e ([(Ru(1a e)2]2+),
respectively. The ligands and their
complexes were characterized by 1H
NMR spectroscopy, ES-MS, and ele-
mental analysis. Single-crystal X-ray
analysis of 2a and 2e demonstrated
that the triazine core is nearly coplanar
with the non-coordinating ring, with di-
hedral angles of 1.2 and 18.68, respec-
tively. The redox behavior and elec-
3
energy of the MLCT state and creat-
ing a large energy gap to the dd state.
Keywords: ligand
luminescence
ruthenium ¥ triazines
design
N ligands
¥
¥
¥
Introduction
Over the past two decades, ruthenium polypyridyl com-
plexes have attracted considerable attention due to their
outstanding photophysical properties.[1] The prototypical
[Ru(bpy)3]2+ (bpy=2,2’-bipyridine) and [Ru(tpy)2]2+ (tpy=
2,2’:6’,2’’-terpyridine) complexes are stable to a wide range
of oxidative and reductive conditions, and are also photosta-
ble under suitable experimental conditions. The
[Ru(bpy)3]2+ motif has been studied more extensively due
to its facile synthesis and superior photophysical properties
as compared to [Ru(tpy)2]2+. These enhanced properties in-
clude a longer room-temperature (RT) excited-state life-
time, which is critical for applications in practical devices,[2]
and a higher quantum yield. However, as the [Ru(bpy)3]2+
motif is stereogenic, polymetallic complexes based thereon
will give rise to a complicated mixture of isomers.[3] On the
other hand, the achiral [Ru(tpy)2]2+ motif has the advantage
of forming unique polymetallic complexes when substituted
in the 4’-position,[4] and thus simplifies synthesis. The short
[a] Dr. M. I. J. Polson, E. A. Medlycott, Prof. Dr. G. S. Hanan
Dÿpartement de Chimie, Universitÿ de Montrÿal
2900 Edouard Montpetit, Montrÿal, QC, H3T1J4 (Canada)
Fax : (+1)514-343-7586
E-mail: garry.hanan@umontreal.ca
[b] L. Mikelsons, Dr. N. J. Taylor
Department of Chemistry, University of Waterloo
200 University Ave., Waterloo, Ontario, N2L3G1 (Canada)
[c] M. Watanabe, Prof. Dr. Y. Tanaka
Faculty of Engineering, Shizuoka University
Hamamatsu, 432-8561 (Japan)
[d] Dr. F. Loiseau, R. Passalacqua, Prof. Dr. S. Campagna
Dipartimento di Chimica Inorganica
Chimica Analitica e Chimica Fisica
Universit‡ di Messina, 98166 Messina (Italy)
Fax : (+39)090-393756
E-mail: photochem@chem.unime.it
3640
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/chem.200400032
Chem. Eur. J. 2004, 10, 3640 3648

3640 3648
RT excited-state lifetime of [Ru(tpy)2]2+ has also spurred ef-
forts to develop RT luminescent analogues.[5] These efforts
have met with limited success, usually requiring multistep
syntheses or expensive starting materials.[6]
Here we report the full synthetic details and properties of
triazine-based tridentate ligands that exhibit improved RT
excited-state lifetimes in their RuII complexes compared to
the prototypes [Ru(tpy)2]2+ and [Ru(4’-phenyl-tpy)2]2+
.
We recently reported a new strategy to improve RT lumi-
nescence in [Ru(tpy)2] complexes by using a coplanar ar-
rangement of aromatic substituents on the terpyridine
ligand.[7] The idea was based on the observation that appro-
priately substituted heterocyclic rings lead to a coplanar ar-
rangement of rings, as opposed to the slight twist found be-
tween aromatic hydrocarbon rings (Figure 1).[8] Coplanarity
Their inexpensive starting materials and superior photophys-
ical properties make these new species ideal candidates for
incorporation into larger supramolecular assemblies and de-
vices.[15]
Results and Discussion
Synthesis and characterization: The three ligands with aro-
matic hydrocarbon rings, 1a c, were synthesised by treating
two equivalents of 2-cyanopyridine with the lithium amidi-
nide salt of the appropriate aromatic hydrocarbon in diethyl
ether (Scheme 1). The amidinide salt was obtained in situ
Figure 1. Coplanar and nonplanar arrangements of substituted terpyri-
dines.
of heterocyclic rings has also been found to introduce inter-
esting properties into ruthenium complexes of bidentate li-
gands,[9] including ion-sensing properties in diruthenium
complexes.[10]
The improvement can be seen by comparing the RT excit-
ed-state lifetimes of RuII complexes of 4’-phenyl-tpy (0.5 ns,
Figure 1a) and 4’-p-tolyl-tpy (0.95 ns) to the tpy analogue 4’-
(2-pyrimidyl)-tpy (8 ns, (Figure 1b). The 4’-phenyl-tpy and
4’-p-tolyl-tpy ligands have unfavorable steric interactions be-
tween the H atoms adjacent to the interannular bond that
cause twisting in the rings and less favorable p-orbital over-
lap between them as compared to 4’-(2-pyrimidyl)-tpy. In
the last-named, coplanarity of the rings is achieved by sub-
stituting a series of functionalized 2-pyrimidyl groups in the
4’-position of tpy (Figure 1b). This arrangement allows the
Scheme 1. Preparation of ligands 1a c.
from the appropriate aryl cyanide and lithium dimethyl-
amide. Ligands 1a c were isolated from the reaction mixture
by filtration and purified by recrystallization from EtOH/
H2O. The yield varied from 93% for unsubstituted 1a to
23% for sterically encumbered ortho-methyl-substituted 1b.
The synthesis of 1a is also possible in THF, albeit with a
lower overall yield (70%).
Under the same reaction conditions, heterocyclic cyanides
failed to afford the desired ligands 1d,e. Heterocyclic li-
gands 1d,e could be obtained (Scheme 2) by modifying a lit-
erature procedure (1d) or by a statistical reaction based on
the same procedure (1e). In both cases, two equivalents of
2-cyanopyridine were combined with one equivalent of 2-
cyano- (1d) or 4-cyanopyridine (1e) and heated to 1808C in
the presence of a catalytic amount of NaH. In the case of
1d, the solid mass was extracted with toluene, and the re-
sulting solid recrystallized from EtOH to afford 1d in 67%
yield. In the synthesis of 1e, the resulting solid was treated
with aqueous NiCl2 after toluene extraction.[16] NiCl2 forms
a complex with 1e and any 1d that formed due to the statis-
tical nature of the reaction. The aqueous phase was then ex-
tracted with dichloromethane to remove any bis- or tris(4-
pyridyl)triazine formed during the reaction, and after de-
À
central and noncoordinating rings to undergo favorable C
H¥¥¥N hydrogen bonding and thus lie coplanar with one an-
other, which increases p-orbital overlap between the rings.
Although the RT excited-state lifetimes of the Ru complexes
of the substituted 4’-(2-pyrimidyl)-tpy are increased dramati-
cally (up to 200 ns),[7] six steps are required to obtain these
ligands from commercially available materials. A new ap-
proach to this strategy is to build up ligands with the addi-
tional N atoms on the central ring and not on the noncoor-
dinating ring (Figure 1c). Although the synthesis and com-
plexation of tris-substituted triazines have been described
(e.g., tris-(2-pyrimidyl)-s-triazine[11] and tris-(2-pyridyl)-s-tri-
azine[12]), almost no attention has been paid to the synthesis
of unsymmetrically substituted tridentate ligands containing
a central triazine ring. This stems in part from a relatively
limited set of reaction conditions for building up the bis-(2-
pyridyl)-s-triazine core of the ligands.[13] We recently pre-
sented a straightforward synthesis of unsymmetrically substi-
tuted tridentate triazine-based ligands and showed that their
Ru complexes have interesting photophysical properties that
include RT luminescence in liquid solution.[14]
Chem. Eur. J. 2004, 10, 3640 3648
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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G. S. Hanan, F. Loiseau et al.
FULL PAPER
Scheme 2. Preparation of ligands 1d,e.
Scheme 3. Preparation of ruthenium complexes 2 and 3.
complexation of the Ni complexes with CNÀ, ligands 1d and
1e were collected and separated by recrystallization to
afford 1e in 24% yield.
afforded by elemental analysis. Hydrates of each complex
were obtained, which is typical for ruthenium polypyridyl
complexes.[17]
1
Heteroleptic Ru complexes 2a e were synthesised by
treating [Ru(tpy)Cl3] with ligands 1 in the presence of
AgNO3 in EtOH/H2O (Scheme 3a). The use of silver and an
extended reaction time were critical for disfavoring the for-
mation of two as-yet unidentified purple by-products. The
complexes still required column chromatography to remove
small amounts of these impurities. In the case of homoleptic
complexes 3a e, the formation of purple impurities was un-
avoidable in the traditional one-step synthesis, even with an
excess of silver (Scheme 3b). In a stepwise approach, prepa-
ration of trichlororuthenium(iii) complex 4 (Scheme 3c) fol-
lowed by synthesis of 3a (Scheme 3d) gave an improved
yield of 50% over two steps (vs 35%), as less purple by-
products were formed.
The H NMR resonances for ligands 1 and complexes 2
and 3 are listed in Table 1, and the numbering scheme is
given in Scheme 3. There is a pronounced shift in the
1H NMR resonances of the ligand protons due to several
factors that affect their chemical shifts on metal complexa-
tion. Firstly, the conformation of the pyridine N atoms
changes from transoid to cisoid to permit metal chelation.
As the nitrogen lone pairs deshield the ligand protons adja-
cent to the interannular bond in the transoid form of the li-
gands, metal complexation typically causes an upfield shift
in their resonances in tpy complexes (cf. tpy and
[Ru(tpy)2]2+ in Table 1). In the case of complexes 2 and 3,
the H3,3’’ protons are forced into the plane of the central tria-
zine ring, and this causes significant deshielding compared
to HT3,3’’ on the tpy ligands in complexes 2 (Table 1). Second-
ly, the coordinated metal ion shifts the ligand proton reso-
nances adjacent to the N atom upfield due to the magnetic
anisotropy of the bound metal ion.[18] The H6,6’’ protons of
complexes 2 and 3 clearly follow this trend, although the
Low-resolution electrospray mass spectrometry confirmed
the molecular mass of complexes 2 and 3, which ionize to
their 1+ and 2+ species. In each case, the charge is associ-
À
ated with the successive loss of the PF6 counterions. Fur-
ther confirmation of the purity of the metal complexes was
Table 1. 1H NMR chemical shifts for ligands 1 and Ru complexes 2 and 3.[a]
3,3’’
4,4’’
5,5’’
6,6’’
2’’’
3’’’
4’’’
5’’’
6’’’
Me
T3,3’’
T4,4’’
T5,5’’
T6,6’’
T3’
T4’
1a
1b
1c
1d
8.75
8.75
8.80
8.77
8.79
7.89
7.93
7.94
7.88
7.95
7.47
7.50
7.51
7.46
7.53
8.90
8.92
8.93
8.90
8.91
8.75
7.51
7.43
7.36
8.77
8.56
7.56
7.43
7.51
7.43
7.36
7.46
8.56
8.75
8.26
8.69
8.90
8.85
2.79
2.46
8.69
8.85
7.88
1e
tpy
8.62
8.50
8.50
8.50
8.48
8.50
8.50
7.86
7.42
7.91
7.92
7.91
7.91
7.91
7.33
7.17
7.11
7.13
7.10
7.10
7.10
8.70
7.34
7.44
7.46
7.44
7.41
7.43
8.46
8.76
8.78
8.77
8.77
8.79
8.79
7.96
8.42
8.46
8.45
8.45
8.48
8.49
[Ru(tpy)2]2+
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
9.06
8.98
9.04
9.02
9.10
9.10
9.00
9.07
9.06
9.14
8.11
8.08
8.09
8.11
8.13
8.13
8.10
8.11
8.13
8.15
7.40
7.39
7.38
7.42
7.41
7.38
7.38
7.36
7.39
7.41
7.57
7.55
7.54
7.59
7.59
7.71
7.72
7.67
7.73
7.71
9.06
8.94
7.83
7.69
7.62
9.05
8.85
7.85
7.64
7.63
9.06
8.87
7.83
7.69
7.83
7.69
7.62
7.77
8.85
7.85
7.64
7.63
7.79
8.87
9.06
8.75
8.94
9.12
9.05
9.10
8.78
8.96
9.15
9.08
3.12
2.57
8.23
9.05
9.10
7.85
7.64
3.14
2.59
8.96
9.08
8.25
[a] Ligands 1 and tpy in CDCl3, and complexes 2 3 and [Ru(tpy)2]2+ in CD3CN; see Scheme 3 for numbering scheme. tpy is assigned in an analogous
way to ligands 1 and has the additional prefix T.
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Chem. Eur. J. 2004, 10, 3640 3648

Readily Accessible Tridentate N Ligands
3640 3648
H5,5’’ protons show only a very slight shielding effect due to
metal complexation.
The perpendicular arrangement of the ligands also affects
the proton resonances in complexes 2 and 3. The location of
the protons ortho to the N atom in the peripheral pyridine
rings (H6,6’ and HT6,6’’) above the central heterocycle of the
orthogonal ligand causes a significant upfield shift due to a
ring-current effect. The proton para to the N atom in the
central tpy pyridine ring (HT4’) is held in the deshielding
plane of the two terminal pyridine rings of ligands 1. Both
of these factors have previously been used as a measure of
interligand shielding effects.[19] The external terpyridine res-
T6
onances (HT3 and HT3 T5’) are all within 0.05 ppm of each
other; this indicates almost no difference in their local envi-
ronments.
Variations in the solution concentrations of the ligands
and complexes had very little effect on the chemical shifts
of the protons, except in one particular case. Parent ligand
1a, exhibited large shifts in its proton resonances on dilution
from 10À3 to 10À5 m (Figure 2). Chemical shift changes of up
Figure 3. ORTEP representations of the X-ray crystal structures of com-
plexes 2a (top) and 2e (bottom). The PF6 counteranions have been omit-
ted for clarity.
À
ble for hydrogen bonding to the C H bonds on the phenyl
Figure 2. 1H NMR spectra of ligand 1a at low (top, 5î10À5 m) and high
(bottom, 5î10À3 m) concentration in CDCl3.
substituent of 1a. This also has consequences for the elec-
tro- and photochemistry of complexes 2 and 3 (vide infra).
The X-ray crystal structure of heteroleptic ruthenium
complex 2e (Figure 3, bottom) contains mutually orthogonal
tpy and 1e ligands in a pseudo-octahedral geometry around
to 0.9 ppm were observed, and every proton resonance was
affected. The other ligands in this family displayed shifts of
less than 0.1 ppm on similar dilution. A possible explanation
is that the ligand can effectively dimerize by noncovalent in-
teractions at higher concentrations, whereby the relatively
electron-rich phenyl group associates with the electron-poor
triazine ring. Although several attempts were made to dem-
onstrate potential dimerization by ES-MS, a molecular ion
for twice the molecular mass of ligand 1a was not observed.
À
the metal ion. The Ru N bond length to the triazine ligand
of 1.965(2) ä is identical to that of 2a and slightly shorter
than the Ru N bond length to the tpy ligand (1.989(2) ä).
The pyridine ring is twisted by 17.68 relative to the central
triazine ring. The twist in the dihedral angle (N30-C29-C37-
C38) appears to occur in spite of the favorable C H to N at-
traction between the triazine ring and the 4-pyridyl group.
In addition, crystal-packing forces do not appear to be the
cause, as no close contacts are noted in the extended solid-
state structure of 2e.
À
À
Crystal structure determination of [2a](PF6)2 and
[2e](PF6)2[20]: The X-ray crystal structure of heteroleptic
ruthenium complex 2a (Figure 3, top) contains mutually or-
Electrochemistry: The electrochemistry of complexes 2 and
3 was studied in acetonitrile versus TBAPF6 with ferrocene
as internal standard. The data are gathered in Table 2, along
with reported values for [Ru(tpy)2]2+ as a model.
All the compounds exhibit one one-electron reversible ox-
idation process, except 3e, which undergoes an irreversible
oxidation, and three (2a e) or four (3a e) one-electron re-
versible reduction processes. The oxidation processes are as-
cribed to oxidation of the metal centers, as found for other
RuII polypyridyl complexes,[1,23] whereas the reduction pro-
cesses are all centered on the ligand orbitals.
thogonal tpy and 1a ligands. The pseudo-octahedral geome-
[21]
try around the metal ion is similar to that of [Ru(tpy)2]2+
.
À
The Ru N bond length (central triazine N) of 1.9648(16) ä
is similar to that of 1.9824(16) ä for the central pyridine N
atom in the tpy moiety. The phenyl ring in ligand 1a is twist-
ed by 1.28 relative to the central triazine ring. The dihedral
angle N4-C7-C14-C15 is smaller than that found in any
ruthenium 4’-phenyl-2,2’:6’,2’’-tpy complex.[22] In the case of
À
2a, there are no unfavorable H H interactions ortho to the
interannular bond, and the triazine N lone pairs are availa-
Chem. Eur. J. 2004, 10, 3640 3648
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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G. S. Hanan, F. Loiseau et al.
FULL PAPER
Table 2. Electrochemical redox potentials [V] (DEp) for ligands 1 and complexes 2 and 3 in argon-purged ace-
tion potentials (which is relat-
ed to the interaction between
the not yet reduced ligands).
For example, the third and
fourth reduction processes of
3a are separated by 240 mV,
whereas the first and second
reduction processes are sepa-
rated by 170 mV (Table 2).
This indicates that the interac-
tion between the ligands is in-
creased by reduction processes.
tonitrile.[a]
Oxidation
Reductions
1a
1b
1c
1d
1e
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
À1.50 (60)
À1.51 (75)
À1.51 (84)
À1.44 (90)
À1.36 (83)
À0.77 (77)
À0.78 (72)
À0.78 (75)
À0.74 (70)
À0.69 (72)
À0.71 (65)
À0.73 (70)
À0.74 (64)
À0.67 (66)
À0.64 (56)
À1.24
1.41 (82)
1.39 (78)
1.39 (82)
1.45 (93)
1.46 (94)
1.51 (81)
1.50 (85)
1.50 (101)
1.60 (99)
1.61 (irr)
1.30
À1.38 (66)
À1.64 (80)
À1.64 (78)
À1.64 (80)
À1.62 (97)
À1.59 (74)
À1.51 (74)
À1.52 (76)
À1.53 (84)
À1.49 (97)
À1.43 (81)
À1.38 (69)
À1.39 (89)
À1.37 (76)
À1.34 (70)
À0.88 (69)
À0.90 (75)
À0.90 (70)
À0.86 (71)
À0.82 (74)
À1.49
À1.75 (78)
À1.77 (76)
À1.78 (87)
À1.75 (90)
À1.69 (91)
Electronic absorption spectra:
The electronic absorption spec-
tra of ligands 1 and their metal
complexes 2 and 3 were meas-
ured in acetonitrile (Table 3).
The electronic spectra of li-
[Ru(tpy)2]2+ [b]
[a] Versus SCE with ferrocene as internal standard. [b] From reference [25].
gands
1 are dominated by
The oxidation potentials of all complexes are more posi-
tive than that of [Ru(tpy)2]2+ due to the stabilization of the
metal-based orbitals by the triazine ring of ligands 1. In a
similar fashion, the Ru centers of homoleptic complexes 3a e
are all more difficult to oxidize than those of heteroleptic
complexes 2a e due to stabilization of the metal ion by the
second triazine ring.
Comparison of the reduction potentials of heteroleptic
complexes 2a e with those of [Ru(tpy)2]2+ (Table 2) is
useful for attributing the processes to the various ligand or-
bitals. The first reduction waves of 2a e (around À0.75 V)
occur at potentials much less negative than the first one of
[Ru(tpy)2]2+. The first process can therefore be assigned to
the reduction of the more electron deficient triazine-based
ligand. Complexes 2a e undergo second reduction process-
es, one-electron and reversible, at slightly less negative po-
tentials than the second reduction of [Ru(tpy)2]2+, and these
are attributed to the reduction of the terpyridine ligand. The
third reduction wave around À1.60 V is due to the second
reduction process centered on the triazine-based ligand
(e.g., Figure 4a).
moderately intense absorption bands near 240 and 275 nm
attributed to p p* transitions. Complexes 2 and 3 exhibit
absorption spectra typical of RuII polypyridine com-
pounds,[1,2,26] characterized by ligand-centered p p* transi-
tions in the UV region and metal-to-ligand charge-transfer
(MLCT) transitions in the visible part of the spectrum
(Figure 5). Moreover, additional bands in the UV region
near 300 and 330 nm are ascribed to the lower energy of tri-
azine p p* transitions as compared to terpyridine-based
The reduction pattern of the homoleptic complexes 3a
e[24] shows four reduction processes, all reversible and one-
electron (e.g., Figure 4b). The first two reduction waves can
be attributed to successive reduction processes centered on
the two triazine-based ligands. The first waves occur at
slightly less negative potentials than those of complexes 2,
due to the presence of a second electron-deficient ligand 1
on the metal center. The second ligand becomes more diffi-
cult to reduce after addition of the first electron to the com-
plex, that is, electronic communication between the ligands
is efficient. The next two reduction waves, which present the
same pattern as the first two (cf. the third reduction poten-
tials of complexes 2a e), correspond to the second reduc-
tion processes of each of the two ligands. Interestingly, in
the homoleptic complexes 3 (Table 2), the difference be-
tween the third and fourth reduction potentials (which is re-
lated to the interaction between the monoreduced ligands)
is larger than the difference between first and second reduc-
Figure 4. Cyclic voltammograms in acetonitrile with 0.1m TBAPF6 for
complexes 2a (top) and 3a (bottom) at 100 mVsÀ1
.
3644
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 3640 3648

Readily Accessible Tridentate N Ligands
3640 3648
Table 3. Electronic absorption maxima for ligands 1 and complexes 2 and 3.[a]
Wavelength lmax [nm] (e [103 cmÀ1 molÀ1 dm3]
transition in compounds 2,
which is consistent with their
having two triazine moieties
per complex, as they stabilize
the metal-based orbitals more
than tpy does (cf. electrochem-
ical data above). It is notewor-
thy that the highest energy Ru-
to-1 MLCT transitions occur in
2b and 3b. The aryl group is
no longer coplanar with the tri-
azine ring due to the ortho-
methyl group, and this dimin-
ishes the size of the acceptor
orbital.
1MLCT
Ligand-centered p p* transitions
1a
1b
1c
1d
276 (40.8)
280 (42.2)
278 (40.4)
278 (31.7)
278 (28.5)
243 (25.0)
244 (21.6)
244 (25.0)
244 (26.6)
244 (37.1)
1e
[Ru(tpy)2][b]
474 (10.4)
515 (22.2)
473 (17.7)
514 (12.1)
470 (19.3)
519 (15.4)
473 (16.9)
474 (19.6)[c]
475 (17.6)[c]
481 (24.6)
474 (13.9)
482 (17.8)
500 (21.5)[c]
508 (24.2)[c]
2a
332 (21.1)
331 (25.3)
331 (24.3)
299 (47.9)
279 (50.6)
281 (53.8)
281 (39.0)
272 (48.2)
242 (23.9)
243 (27.7)
243 (21.8)
2b
2c
300 (53.1)
302 (43.3)
273 (53.3)
272 (39.1)
2d
2e
3a
3b
3c
3d
3e
331 (24.5)
331 (21.6)
299 (50.1)
298 (42.1)
280 (51.0)
282 (50.7)
284 (73.2)
277 (41.3)
277 (43.1)
277 (65.4)
284 (82.9)
273 (51.9)
273 (54.2)
242 (27.1)
243 (42.1)
242 (24.4)
243 (21.8)
243 (19.2)
240 (28.6)
253 (33.7)
329 (15.5)
322 (34.4)
338 (15.5)
341 (15.3)
291 (40.3)
295 (40.8)
307 (43.5)
317 (36.0)
Photophysics: Most of the
complexes exhibit lumines-
cence both at room tempera-
ture in liquid acetonitrile and
at 77 K in butyronitrile rigid
matrix. The photophysical data
[a] In acetonitrile. [b] From reference [25]. [c] Broad.
are gathered in Table 4, and the emission spectra of some of
the compounds are shown in Figure 6. It is well known that
the excited state responsible for the luminescence of RuII
polypyridine complexes is the lowest lying triplet MLCT ex-
cited state.[1,2,23] In heteroleptic compounds 2 and homolep-
3
tic complexes 3, the emitting MLCT level involves the tria-
zine-based ligand. At room temperature, the luminescence
quantum yields are between one and two orders of magni-
tude higher than that of [Ru(tpy)2]2+, and the excited state
lifetimes are significantly longer (5 15 ns). For homoleptic
complexes 3b and 3c having less electron withdrawing sub-
stituents on the triazine rings, no luminescence could be de-
tected at room temperature, and the RT emission of com-
pound 3d was too weak to allow the measurement of its life-
time and quantum yield. In all the other cases in which lu-
minescence was recorded, a significant red shift of the emis-
Figure 5. Absorption spectra for complexes 2e (solid line) and 3e (dotted
line) in acetonitrile. Absorption maxima are given in Table 3.
complexes.[27] The MLCT absorption maxima of heteroleptic
sion maximum was observed relative to that of [Ru(tpy)2]2+
,
complexes
2
are very similar to that of [Ru(tpy)2]2+
that is, additional nitrogen atoms on the central ring of the
tridentate ligand stabilize the acceptor orbital of the MLCT
excited state. Moreover, the presence of electron-withdraw-
ing substituents on the triazine moiety further decreases the
emission energy of the complexes. The emission energies of
(Table 3) and are ascribed to a spin-allowed Ru-to-tpy
MLCT transition. Each of complexes 2 has a lower energy
absorption band (ca. 510 520 nm) which is ascribed to a
spin-allowed Ru-to-1 MLCT transition (Figure 5). The lower
energy of these MLCT transi-
tions is due to the low-lying p*
Table 4. Photophysical data for complexes 2 and 3.
Luminescence, 298 K[a]
level of ligands 1, as they con-
tain an electron-deficient tria-
zine ring.[28] The aryl substitu-
ent in the triazine 2-position
also plays a role in lowering
the energy of this band by ex-
tending the acceptor orbitals
over an additional aromatic
ring. The corresponding homo-
leptic complexes 3 all exhibit
MLCT absorption bands at
slightly higher energies with
respect to the Ru-to-1 MLCT
77 K[b]
lmax [nm]
compound
lmax [nm]
t [ns]
f
kr [sÀ1
]
knr [sÀ1
]
t [ms]
2a
2b
2c
2d
2e
3a
740
732
734
745
752
710
9
8
5
11
15
8
5î10À5
4î10À5
2î10À5
6î10À5
7î10À5
9î10À5
5î103
5î103
3î103
5î103
4î103
11î103
11î107
12î107
20î107
9.1î107
6.7î107
1.2î107
695
685
679
700
707
672
677
667
688
686
598
1.1
1.1
1.4
1.0
1.3
1.4
1.7
1.6
1.5
2.2
10.6
3b
3c
3d
3e
730
722
629
4
0.25
10î10À6
3î103
250.0î106
[Ru(tpy)2]2+ [c]
ꢀ5î10À6
[a] In deaerated CH3CN. [b] In butyronitrile. [c] From reference [5].
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2004, 10, 3640 3648
www.chemeurj.org
3645

G. S. Hanan, F. Loiseau et al.
FULL PAPER
to the stabilization of the metal orbitals by the presence of a
second triazine-based ligand.
Conclusion
The synthetic procedures described here give ready access
to a variety of aryl-substituted bis(2-pyridyl)-1,3,5-triazines.
These tridentate ligands are excellent analogues of 2,2’:6’,2’’-
terpyridine, as they readily form transition metal complexes
with a wide variety of metal ions. Both their homo- and het-
eroleptic ruthenium complexes display lower energy light
absorption as compared to [Ru(tpy)2]2+. The concomitant
decrease in the nonradiative decay pathways increases the
room-temperature excited-state lifetimes of the complexes.
All of the heteroleptic RuII complexes 2a e are luminescent
at room temperature. Indeed, complexes 2a e have some of
the longest lifetimes for monochromophoric excited states
that emit beyond 730 nm. In the homoleptic series of RuII
complexes, only complexes 3a and 3e have significant
room-temperature excited-state lifetimes. The incorporation
of triazine-based ligands 1a e into supramolecular assem-
blies by way of their RuCl3 adducts (cf. 4) may increase the
room-temperature lifetime of the assemblies as compared to
tpy or 4’-tolyl-2,2’:6’,2’’-terpyridine analogues. We are cur-
rently exploring the synthetic versatility of ligands 1a e in
assembling supramolecular arrays and will examine their
photophysical properties.
Figure 6. Normalized (uncorrected) emission spectra in liquid acetonitrile
at room temperature (bottom) of 2b (dashed line), 2e (dotted line), and
3e (solid line); and in butyronitrile rigid matrix at 77 K (top) of 2c
(dashed line), 2e (dotted line), and 3c (solid line). Corrected values of
emission maxima are given in Table 4.
homoleptic complexes 3 are higher than those of heterolep-
tic complexes 2; this is explained by the presence of a
second triazine ring on the ruthenium center, which stabiliz-
es the metal-centered orbital. Complex 2e exhibits the lon-
gest excited-state lifetime (15 ns) as a result of the most
electron accepting substituent on the triazine moiety, and
this is the longest lifetime for a long-wavelength emission
(>750 nm) in a [Ru(tpy)2]2+-type complex. As was previ-
ously observed for a series of analogous pyrimidyl terpyri-
dine-based RuII complexes (Figure 1b),[7] the compounds
studied here do not obey the energy-gap law. Indeed, in the
present complexes, as is common for RuII compounds con-
taining tridentate polypyridine ligands, the main pathway
for MLCT decay at RT is activated surface crossing to a
higher lying metal-centered (MC) state.[1d,2a,7,10] Red shift of
emission energy (i.e., of the MLCT state) translates into a
decreased efficiency of this thermally activated process (de-
creased knr), and therefore an increase in luminescence life-
time is obtained. Comparison with results obtained for pyri-
midyl terpyridine analogues of the type shown in Figure 1b
indicates that enhancement of excited-state lifetimes is less
efficient in the present case, most likely because the effect
of enhanced delocalization in the acceptor ligand of the
MLCT state, which is present in the pyrimidyl terpyridine
complexes, is less effective here, since the acceptor orbitals
are mostly centered on the triazine ring. In a rigid matrix at
77 K, all the complexes are luminescent, with emission
Experimental Section
General: Electronic absorption spectra were recorded on a Varian Cary
500 spectrophotometer. For steady-state luminescence measurements, a
Jobin Yvon-Spex Fluoromax 2 spectrofluorimeter was used, equipped
with a Hamamatsu R3896 photomultiplier, and the spectra were correct-
ed for photomultiplier response by using a program purchased with the
fluorimeter. For the luminescence lifetimes, an Edinburgh OB 900 single-
photon-counting spectrometer was used, employing a Hamamatsu PLP2
laser diode as pulse (wavelength output, 408 nm; pulse width, 59 ps).
Emission quantum yields were measured at room temperature using the
optically dilute method.[29] [Ru(bpy)3]2+ in air-equilibrated aqueous solu-
tion and [Ru{Ru(bpy)2(m-2,3-dpp)}3]8+ (2,3-dpp=2,3-bis(2’-pyridyl)pyra-
zine) in deaerated acetonitrile were used as quantum-yield standards
with values of 0.028[30] and 0.005,[31] respectively.
Electrochemical measurements were carried out in argon-purged acetoni-
trile at room temperature with a BAS CV50W multipurpose instrument
interfaced to a PC. The working electrode was a Pt electrode, the coun-
terelectrode was a Pt wire, and the pseudoreference electrode was a
silver wire. The reference was set using an internal 1mm ferrocene/ferro-
cinium sample at 395 mV versus SCE in acetonitrile and 432 mV in
DMF. The concentration of the compounds was about 1mm. Tetrabutyl-
ammonium hexafluorophosphate (TBAPF6) was used as supporting elec-
trolyte at a concentration of 0.10m. Cyclic voltammograms were obtained
at scan rates of 50, 100, 200, and 500 mVsÀ1. For reversible processes,
half-wave potentials (vs SCE) were measured with Osteryoung square-
wave voltammetry (OSWV) experiments performed with a step rate of
4 mV, a pulse height of 25 mV, and a frequency of 15 Hz. For irreversible
oxidation processes, the cathodic peak was used as E, and the anodic
peak was used for irreversible reduction processes. The criteria for rever-
sibility were a separation of 60 mV between cathodic and anodic peaks, a
ratio of the intensities of the cathodic and anodic currents close to unity,
and constancy of the peak potential on changing scan rate. The number
maxima again red-shifted relative to that of [Ru(tpy)2]2+
,
and exhibit longer excited-state lifetimes, on the microsec-
ond timescale. In the case of complexes 2, the emission
energy decreases with increasing electron-withdrawing ca-
pacity of the substituent on the triazine ring, whereas in the
case of homoleptic complexes this effect is less linear, due
3646
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 3640 3648

Readily Accessible Tridentate N Ligands
3640 3648
of exchanged electrons was measured by OSWV and by taking advantage
of the presence of ferrocene used as the internal reference.
8.75 (d, J=8.0 Hz, 1H; H5’’’), 8.50 (d, J=8.5 Hz, 2H; T3,3’’), 8.45 (t, J=
8.5 Hz, 1H; T4’), 8.08 (t, J=8.0 Hz, 2H; H4,4’’), 7.92 (t, J=8.0 Hz, 2H;
T4,4’’), 7.69 (m, 3H; H2’’’,3’’’,4’’’), 7.55 (d, J=5.0 Hz, 2H; H6,6’’), 7.46 (d, J=
5.5 Hz, 2H; T6,6’’), 7.39 (t, J=6.0 Hz, 2H; H5,5’’), 7.13 (t, J=6.5 Hz, 2H;
T5,5’’), 3.12 (s, 3H; CH3); MS (ESI): m/z: 804.1 [MÀPF6]+, 329.6
[MÀ2PF6]2+; elemental analysis calcd (%) for C35H26N8RuP2F12¥H2O: C
43.17, H 3.52, N 11.51; found: C 42.78, H 3.01, N 11.51.
Experimental uncertainties: absorption maxima, Æ2 nm; molar absorp-
tion coefficient, 10; emission maxima, Æ5 nm; excited state lifetimes,
10%; luminescence quantum yields, 20%; redox potentials, Æ10 mV.
Compounds 1d,[32] 2d,[12b] 3d,[24] and [Ru(tpy)Cl3][33] were synthesised as
previously described. Solvents were removed under reduced pressure on
a rotary evaporator unless otherwise stated.
Compound 2c: Yield 128 mg (86%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); d=9.04 (d, J=7.5 Hz, 2H; H3,3’’), 8.94 (d, J=8.0 Hz, 2H;
H2’’’,6’’’), 8.77 (d, J=8.0 Hz, 2H; T3’,5’), 8.48 (d, J=8.5 Hz, 2H; T3,3’’), 8.45
(t, J=8.5 Hz, 1H; T4’), 8.09 (t, J=8.0 Hz, 2H; H4,4’’), 7.91 (t, J=8.0 Hz,
2H; T4,4’’), 7.62 (d, J=8.5 Hz, 2H; H3’’’,5’’’), 7.54 (d, J=5.0 Hz, 2H; H6,6’’),
7.44 (d, J=5.5 Hz, 2H; T6,6’’), 7.38 (t, J=6.0 Hz, 2H; H5,5’’), 7.10 (t, J=
6.5 Hz, 2H; T5,5’’), 2.57 ppm (s, 3H; CH3); MS (ESI): m/z: 804.2
Triazine ligands 1a c: The corresponding aryl cyanide (3.84 mmol) was
added to LiNMe2 (200 mg) in diethyl ether (50 mL). After stirring for
30 min under nitrogen, 2-cyanopyridine was added (800 mg, 7.69 mmol).
A precipitate formed rapidly and the resulting suspension was stirred
overnight. The mixture was then poured into a 1:1 mixture of ethanol
and water (200 mL). The solution was boiled on a hot plate to remove
ethanol and diethyl ether. On cooling, a precipitate formed, which was
collected by filtration.
Compound 1a: Yield 1.12 g (93%); 1H NMR (CDCl3, 300 MHz, TMS):
d=8.90 (d, J=4.5 Hz, 2H; H6,6’’), 8.75 (m, 4H; H3,3’’,2’’’,6’’’), 7.89 (t, J=
7.5 Hz, 2H; H4,4’’), 7.56 (t, J=7.0 Hz, 1H; H4’’’), 7.51 (t, J=7.5 Hz, 2H;
H3’’’,5’’’), 7.47 ppm (dd, J=7.0, 5.0 Hz, 2H; H5,5’’); MS (HREI): m/z:
311.1181 [M]+; elemental analysis calcd (%) for C19H13N5: C 73.29, H
4.21, N 22.49; found: C 73.00, H 4.17, N 22.51.
Compound 1b: Yield 255 mg (23%); 1H NMR (CDCl3, 300 MHz, TMS):
d=8.92 (d, J=5.0 Hz, 2H; H6,6’’), 8.75 (d, J=8.0 Hz, 2H; H3,3’’), 8.26 (d,
J=8.0 Hz, 1H; H6’’’), 7.93 (td, Jt =7.5 Hz, Jd =1.5 Hz, 2H; H4,4’’), 7.50
(ddd, J=7.5, 6.0, 1.0 Hz, 2H; H5,5’’), 7.43 (dd, J=7.5, 1.5 Hz, 1H; H3’’’),
7.43 (m, 2H; H4’’’,5’’’), 2.79 ppm (s, 3H; HMe). MS (HREI): m/z: 325.1316
[M]+; elemental analysis calcd (%) for C20H15N5¥0.5H2O: C 71.84, H
4.82, N 20.94; found: C 71.73, H 4.42, N 21.03.
Compound 1c: Yield 468 mg (42%); 1H NMR (CDCl3, 300 MHz, TMS):
d=8.93 (d, J=4.0 Hz, 2H; H6,6’’), 8.80 (d, J=8.0 Hz, 2H; H3,3’’), 8.69 (d,
J=8.0 Hz, 2H; H2’’’,6’’’), 7.94 (td, Jt =7.5 Hz, Jd =1.5 Hz, 2H; H4,4’’), 7.51
(dd, J=7.5, 5.0 Hz, 2H; H5,5’’), 7.36 (d, J=8.0 Hz, 2H; H3’’’,5’’’), 2.46 ppm
(s, 3 H; HMe). MS (HREI): m/z: 325.1328 [M]+; elemental analysis calcd
(%) for C20H15N5¥H2O: C 69.96, H 4.99, N 20.40; found: C 70.24, H 4.91,
N 20.58.
[MÀPF6]+, 329.7 [MÀ2PF6]2+
; elemental analysis calcd (%) for
C35H26N8RuP2F12: C 43.99, H 3.38, N 11.72; found: C 43.85, H 3.01, N
11.47.
Compound 2e: Yield 165 mg (78%); 1H NMR (CD3CN, 300 MHz,
CD2HCN): d=9.10 (m, J=8.0 Hz, 2H; H3,3’’), 9.05 (m, 2H; H2’’’,6’’’), 8.85
(d, J=7.5 Hz, 2H; H3’’’,5’’’), 8.79 (d, J=8.0 Hz, 2H; T3’,5’), 8.50 (d, J=
8.0 Hz, 2H; T3,3’’), 8.49 (t, J=8.0 Hz, 1H; T4’), 8.13 (td, Jt =8.0 Hz, Jd =
1.5 Hz, 2H; H4,4’’), 7.91 (td, Jt =8.0 Hz, Jd =1.0 Hz, 2H; T4,4’’), 7.59 (d, J=
5.0 Hz, 2H; H6,6’’), 7.43 (d, J=5.5 Hz, 2H; T6,6’’), 7.41 (td, Jt =5.5 Hz, Jd =
1.5 Hz, 2H; H5,5’’), 7.10 ppm (td, Jt =6.0 Hz, Jd =1.0 Hz, 2H; T5,5’’); MS
(ESI): m/z: 792.5 [MÀPF6]+, 323.9 [MÀ2PF6]2+; elemental analysis calcd
(%) for C33H23N9RuP2F12¥H2O: C 41.52, H 2.64, N 13.21; found: C 41.92,
H 2.94, N 13.16.
Homoleptic complexes 3a e: The appropriate ligand (0.64 mmol) and
AgNO3 (160 mg, 0.96 mmol) were added to a solution of RuCl3¥xH2O
(76 mg, 0.32 mmol) in ethanol (50 mL). The mixture was then stirred and
refluxed overnight. After cooling, the solution was filtered to remove
AgCl and evaporated to dryness. The resulting solid was dissolved in ace-
tonitrile and purified by column chromotography (SiO2, acetonitrile/aq.
KNO3 7:1). The nitrate salt was metathesized to the PF6 salt, and the sol-
vent removed under reduced pressure. The solid was dissolved in acetoni-
trile, and the product precipitated by addition to water.
Compound 3a: Yield 105 mg (35%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); d=9.10 (m, 8H; H3,3’’,2’’’,6’’’), 8.13 (td, Jt =8.0 Hz, Jd =1.0 Hz,
4H; H4,4’’), 7.85 (m, 6H; H3’’’,4’’’,5’’’), 7.71 (d, J=5.5 Hz, 4H; H6,6’’), 7.38 ppm
(td, Jt =7.5 Hz, Jd =1.5 Hz, 4H; H5,5’’); MS (ESI): m/z: 868.3 [MÀPF6]+,
361.9 [MÀ2PF6]2+; elemental analysis calcd (%) for C38H34N10RuP2F12¥-
H2O: C 43.98, H 2.30, N 13.49; found: C 43.87, H 2.69, N 13.51.
Compound 1e: A mixture of 4-cyanopyridine (5 g), 2-cyanopyridine
(5 g), and NaH (200 mg) was heated to 1808C for 30 min. After cooling,
the solid was dissolved in hot toluene (500 mL), and the solution filtered.
While still hot, the toluene was extracted with an aqueous Ni solution
(3 g of NiCl2¥6H2O in 200 mL of water). After cooling, KCN (5 g) was
added and a fine precipitate formed. The crude product was collected by
filtration and recrystallized from ethanol. Yield 2.4 g (24%). 1H NMR
(CDCl3, 300 MHz, TMS): d=8.91 (d, J=3.5 Hz, 2H; H6,6’’), 8.85 (d, J=
5.5 Hz, 4H; H2’’’,6’’’), 8.79 (d, J=7.5 Hz, 2H; H3,3’’), 8.56 (t, J=5.0 Hz, 1H;
H3’’’,5’’’), 7.95 (t, J=7.5 Hz, 2H; H4,4’’), 7.53 ppm (t, J=5.0 Hz, 2H; H5,5’’);
MS (HREI): m/z: 312.1123 [M]+; elemental analysis calcd (%) for
C18H12N6¥0.5H2O: C 67.28, H 4.08, N 26.15; found: C 67.44, H 3.74, N
25.97.
Compound 3b: Yield 115 mg (34%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); d=9.00 (d, J=7.5 Hz, 4H; H3,3’’), 8.78 (d, J=7.0 Hz, 2H;
H5’’’), 8.10 (t, J=7.5 Hz, 4H; H4,4’’), 7.72 (d, J=5.5 Hz, 4H; H6,6’’), 7.64
(m, 6H; H2’’’,3’’’,4’’’), 7.38 (t, J=6.5 Hz, 4H; H5,5’’), 3.14 ppm (s, 6H; HMe);
MS (ESI): m/z: 895.8 [MÀPF6]+, 375.8 [MÀ2PF6]2+
.
Compound 3c: Yield 99 mg (86%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); d=9.07 (d, J=8.0 Hz, 4H; H3,3’’), 8.96 (d, J=8.0 Hz, 4H;
H2’’’,6’’’), 8.11 (t, J=7.5 Hz, 4H; H4,4’’), 7.67 (d, J=5.5 Hz, 4H; H6,6’’), 7.63
(d, J=8.5 Hz, 4H; H3’’’,5’’’), 7.36 (t, J=6.5 Hz, 4H; H5,5’’), 2.59 ppm (s, 6H;
Heteroleptic complexes 2a e: The appropriate ligand (0.23 mmol) and
AgNO3 (115 mg, 0.68 mmol) were added to a suspension of [Ru(tpy)Cl3]
(100 mg, 0.23 mmol) in ethanol (50 mL). The mixture was then stirred
and refluxed overnight. After cooling, the solution was filtered to remove
AgCl and evaporated to dryness. The resulting solid was dissolved in ace-
tonitrile and purified by column chromotography (SiO2, acetonitrile/aq.
KNO3 7:1). The nitrate salt was metathesized to the PF6 salt, and the sol-
vent removed under reduced pressure. The solid was dissolved in acetoni-
trile, and the product precipitated by addition to water.
CH3); MS (ESI): m/z: 376.5 [MÀ2PF6]2+
.
Compound 3e: Yield 150 mg (46%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); d=9.14 (d, J=7.5 Hz, 4H; H3,3’’), 9.08 (d, J=4.5 Hz, 4H;
H2’’’,6’’’), 8.87 (d, J=4.5 Hz, 4H; H3’’’,5’’’), 8.15 (t, J=8.0 Hz, 4H; H4,4’’), 7.71
(d, J=5.0 Hz, 4H; H6,6’’), 7.41 ppm (t, J=7.5 Hz, 4H; H5,5’’); MS (ESI):
m/z: 1017.3 [M+H]+, 871.5 [MÀPF6]+, 363.4 [MÀ2PF6]2+; elemental
analysis calcd (%) for C36H24N12RuP2F12¥H2O: C 41.83, H 2.54, N 16.26;
found: C 41.84, H 2.76, N 16.16.
Compound 2a: Yield 190 mg (90%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); d=9.06 (m, 4H; H3,3’’,2’’’,6’’’), 8.78 (d, J=8.0 Hz, 2H; T3’,5’), 8.50
(d, J=7.5 Hz, 2H; T3,3’’), 8.46 (t, J=8.0 Hz, 1H; T4’), 8.11 (td, Jt =8.0 Hz,
Jd =1.0 Hz, 2H; H4,4’’), 7.91 (td, Jt =7.0 Hz, Jd =1.0 Hz, 2H; T4,4’’), 7.83
(m, 3H; H3’’’,4’’’,5’’’), 7.57 (d, J=5.5 Hz, 2H; H6,6’’), 7.44 (d, J=5.5 Hz, 2H;
Hp6,6’’), 7.40 (td, Jt =5.5 Hz, Jd =1.0 Hz, 2H; H5,5’’), 7.11 ppm (t, J=
Compound 4: Lithium chloride (4 g) was dissolved in ethanol (50 mL)
with sonication. To this solution were added 1a (1 g) and RuCl3¥xH2O
(770 mg). The solution was refluxed overnight and was continuously stir-
red by magnetic stirrer. On cooling the fine brown precipitate was col-
lected by filtration. This crude product was suspended in ethanol, sonicat-
ed for 30 min, collected by filtration, and the process repeated. Yield
1.3 g (78%); elemental analysis calcd (%) for C19H13Cl3N5Ru¥3H2O: C
39.84, H 3.34, N 12.23; found: C 38.50, H 2.59, N 11.88.
6.0 Hz, 2H; T5,5’’); MS (ESI): m/z: 791.4 [MÀPF6]+, 323.5 [MÀ2PF6]2+
;
elemental analysis calcd (%) for C34H32N8RuP2F12¥H2O: C 42.55, H 3.21,
N 11.90; found: C 42.53, H 2.91, N 12.39.
Compound 2b: Yield 152 mg (69%); 1H NMR (CD3CN, 300 MHz,
CD2HCN); 8.98 (d, J=7.5 Hz, 2H; H3,3’’), 8.77 (d, J=8.0 Hz, 2H; T3’,5’),
Compound 3a: Compound 1a (0.32 mmol) and AgNO3 (160 mg,
0.96 mmol) were added to a suspension of 4 (100 mg, 0.32 mmol) in etha-
nol (50 mL). The mixture was then stirred and refluxed overnight. After
Chem. Eur. J. 2004, 10, 3640 3648
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3647

G. S. Hanan, F. Loiseau et al.
FULL PAPER
cooling, the solution was filtered to remove AgCl and then evaporated to
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column chromatography (SiO2, acetonitrile/aq. KNO3 7:1). The nitrate
salt was metathesized to the PF6 salt, and the solvent removed under re-
duced pressure. The solid was dissolved in acetonitrile, and the product
was precipitated by addition to water. Yield 125 mg (64%); physical data
agreed with those given above.
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Acknowledgement
G.S.H. thanks the Natural Sciences and Engineering Research Council of
Canada and the Universitÿ de Montrÿal for financial support. E.A.M.
thanks the Commonwealth for a graduate fellowship. S.C. thanks MIUR
and CNR. F.L. is grateful for a Marie Curie fellowship grant. The EC-
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sized Metal Complexes are also thanked.
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Received: January 13, 2004
Published online: June 9, 2004
3648
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www.chemeurj.org
Chem. Eur. J. 2004, 10, 3640 3648