Synthesis, structure, and photophysical and electrochemical properties of cyclometallated iridium(III) complexes with phenylated bipyridine ligands

Article abstract of DOI:10.1002/ejic.200400418

A series of cationic diiminoiridium(III) complexes [Ir(ppy-N,C) ₂(L-N,N)](PF₆) has been prepared [Hppy = 2-phenylpyridine; L = 4,4′-tBu₂dpbpy (1), 4,4′-Me₂dpbpy (2), 4,4′-Me₂pbpy (3), 4,4′-Me₂bpy (4)] and their photophysical and electrochemical properties studied. X-ray diffraction studies of complex 1 reveal a dihedral angle of about 33° between the pyridine rings, and that the two phenyl groups are also tilted with respect to the adjacent pyridine rings. All the complexes exhibit moderately intense and long-lived emission. The origin of the emission is tentatively assigned to a triplet metal-to-ligand charge-transfer ³MLCT [dπ(Ir) → π* (diimine)] excited state, although the possibility of a triplet σ-bond-to-ligand charge transfer ³SBLCT [σ(Ir-C) → π* (diimine)] cannot be excluded. The luminescence properties of the complexes are dependent on the substituents on the diimine ligands. Selective N-methylation of the diimine ligands has been achieved and their N,C-coordination to the Ir centre has been attempted. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejic.200400418

FULL PAPER
Synthesis, Structure, and Photophysical and Electrochemical Properties of
Cyclometallated Iridium(III) Complexes with Phenylated Bipyridine Ligands
[a]
[b]
[b]
[c]
Marc Lepeltier, Terence Kwok-Ming Lee, Kenneth Kam-Wing Lo,* Loic Toupet,
[a]
[a]
Hubert Le Bozec, and V e´ ronique Guerchais*
Dedicated to Professor David Carillo on the occasion of his 65th birthday
Keywords: Electrochemistry / Iridium / N ligands / Photochemistry
A series of cationic diiminoiridium(III) complexes [Ir(ppy-
N,C) (L-N,N)](PF ) has been prepared [Hppy = 2-phenylpyr- ine)] excited state, although the possibility of a triplet σ-
idine; L = 4,4Ј-tBu
Me pbpy (3), 4,4Ј-Me
metal-to-ligand charge-transfer 3MLCT [dπ(Ir) Ǟ π*(diim-
2
6
3
2
dpbpy (1), 4,4Ј-Me
2
dpbpy (2), 4,4Ј-
bond-to-ligand charge transfer SBLCT [σ(Ir−C) Ǟ π*(diim-
2
2
bpy (4)] and their photophysical and
ine)] cannot be excluded. The luminescence properties of the
electrochemical properties studied. X-ray diffraction studies complexes are dependent on the substituents on the diimine
of complex 1 reveal a dihedral angle of about 33° between
the pyridine rings, and that the two phenyl groups are also
tilted with respect to the adjacent pyridine rings. All the com-
plexes exhibit moderately intense and long-lived emission.
The origin of the emission is tentatively assigned to a triplet
ligands. Selective N-methylation of the diimine ligands has
been achieved and their N,C-coordination to the Ir centre has
been attempted.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Introduction
in particular, aromatic substituents can be introduced in the
[
9,10]
6- and 6Ј-positions.
Such ligands are particularly at-
Cyclometallated polypyridineiridium(iii) complexes have
tractive since they could adopt both N,N and N,C coordi-
nation. The latter coordination mode, involving orthomet-
allation of the aryl group, requires prior N-protection of
one pyridine ring in order to avoid the more facile N,N-
coordination. It is anticipated that sequential N,C-coordi-
nation would allow access to polymetallic systems. We re-
port herein the preparation, molecular structure, and pho-
tophysical and electrochemical properties of a series of
cyclometallated diiminoiridium(iii) complexes [Ir(ppy-
N,C) (L-N,N)](PF ) containing phenyl, methyl and/or tert-
attracted a great deal of interest due to their photophysical
[
1Ϫ8]
properties.
These systems exhibit luminescence emitted
predominantly from triplet MLCT excited states with high
quantum yields. Another interesting feature of these com-
pounds is the possibility to tune the emission energy by
simply modifying the cyclometallating and/or polypyridine
ligands. One class of compounds that has been particularly
well investigated for their photophysical properties and
their use as dopants in organic light-emitting diode
2
6
(
OLED) devices are homoleptic neutral tris(cyclometal-
butyl substituents at various locations of the diimine li-
gands L. The effects of these different substituents on the
luminescence properties of the complexes are discussed. We
also describe here the selective N-methylation reactions of
these ligands and attempts to coordinate them in an N,C-
mode to the Ir centre.
III
[2Ϫ4]
lated) Ir complexes and related complexes.
The design
III
of cationic cyclometalled Ir complexes [Ir(ppy-N,C) (bpy-
2
ϩ
N,N)] (where bpy is 2,2Ј-bipyridine and Hppy is 2-phenyl-
pyridine) has also been reported and their use as biological
labelling reagents has been described recently.
range of substituted 2,2Ј-bipyridines are now available, and,
[5Ϫ8]
A wide
[
a]
Institut de Chimie de Rennes, UMR CNRS-Universit e´ de
Rennes 1 6509, ‘‘Organom e´ talliques et Catalyse’’
Campus de Beaulieu, 35042 Rennes Cedex, France
E-mail: veronique.guerchais@univ-rennes1.fr
Department of Biology and Chemistry,
Results and Discussion
Synthesis and Characterization
[
[
b]
c]
City University of Hong Kong,
The phenylated bipyridine ligands were prepared by
Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
Groupe Mati e` re Condens e´ e, UMR CNRS-Universit e´ de
Rennes 1 6626, Campus de Beaulieu,
[9,10]
classical procedures.
The phenylation reaction of 4,4Ј-
dimethyl-2,2Ј-bipyridine (Me bpy) affords a mixture of
2
35042 Rennes Cedex, France
monophenylated (Me pbpy) and diphenylated (Me dpbpy)
2
2
110
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400418
Eur. J. Inorg. Chem. 2005, 110Ϫ117

Cyclometallated Iridium(iii) Complexes with Phenylated Bipyridine Ligands
FULL PAPER
derivatives. They are readily separated by column chroma- X-ray Crystal Structure of Complex 1
tography and were isolated in 46% and 25% yield, respec-
Crystals were obtained by slow diffusion of diethyl ether
tively. Diphenylation of 4,4Ј-di-tert-butyl-2,2Ј-bipyridine
into a CH Cl solution of 1. The ORTEP diagram is de-
2
2
[10]
(
tBu bpy) is similar to that of Me bpy.
The reaction is
2
2
picted in Figure 1. Selected bond lengths and angles are
performed in refluxing THF, followed by hydrolysis and
oxidation by manganese dioxide. After chromatographic
listed in Table 1. Complex 1 (containing 1.5 H O molecules)
2
exhibits a pseudo-octahedral geometry around the iridium
centre, the two IrϪC bonds being in a cis position as in the
precursor dimer. The IrϪN distances of the diimine ligand
are similar to those of related complexes, and they are in
accordance with a trans influence of the C-cyclometallating
ligands. The slight lengthening of the IrϪN bond is similar
purification, the diphenylated derivative tBu dpbpy was iso-
2
lated as a white solid in 84% yield; formation of the mono-
phenylated product was not observed in this case.
The corresponding complexes [Ir(ppy-N,C) (L-N,N)]-
2
(
PF ) [L ϭ 4,4Ј-tBu dpbpy (1), 4,4Ј-Me dpbpy (2), 4,4Ј-
6 2 2
Me pbpy (3)] were then obtained from the reaction of the
[5d,5g,6,12]
2
to that observed for related cationic complexes.
ortho-metallated dimer [Ir(ppy-N,C) (µ-Cl)] and the appro-
2
2
The bite angle of the tBu dpbpy ligand is similar to that
2
priate diimine ligand L (Scheme 1). For comparison, the
of [Ir(ppy-N,C) (4Ј-R-6Ј-phenyl-2,2Ј-bipyridine-N,N)](PF )
2
6
non-phenylated complex [Ir(ppy-N,C) (Me bpy-N,N)](PF )
[5g]
2
2
6
(
R ϭ OCOC H OCOC H OC H ) [75.2(4)°].
The bi-
6
4
6
4
6
13
(
4) was also prepared. The chloro-bridged dimer was syn-
pyridine rings are not coplanar (dihedral angle 32.97°) and
the 6,6Ј-diphenyl groups are also tilted with respect to the
adjacent pyridine rings (dihedral angles 45.27° and 93.85°).
This is probably due to steric reasons. Moreover, the phenyl
rings are almost coplanar with the phenyl groups of the ppy
[11]
thesized following the procedure of Nonoyoma. The co-
ordination reactions of the diimine ligands to the Ir centre
were performed in refluxing 1,2-dichloroethane; the use of
methanol was avoided due to a protonation side-reaction of
the diimine ligand. The presence of a silver salt is required,
otherwise the starting material is recovered. All the com-
plexes were crystallized from CH Cl /Et O and isolated as
2
2
2
yellow crystals (yield: 70Ϫ80%). Complexes 1Ϫ4 were
1
13
characterized by H and C NMR spectroscopy, and as-
signments were made on the basis of HMBC, HMQC, and
COSY spectra. The heterocycles of the ppy ligands remain
in a trans configuration as in the precursor dimer. Com-
plexes 1Ϫ4 were formed as one isomer of low symmetry, as
indicated by the NMR spectroscopic data. No N,C-chel-
ation was thus observed under the reaction conditions used.
Figure 1. ORTEP representation of complex 1; the unit cell con-
2
tains 1.5 molecules of H O, which have been omitted for clarity, as
Ϫ
has the PF
6
counteranion
˚
Table 1. Selected bond lengths [A] and angles [°] for complex 1
IrϪN(1)
IrϪN(2)
IrϪN(3)
IrϪN(4)
N(1)ϪIrϪN(4)
N(1)ϪIrϪN(3)
N(3)ϪIrϪN(4)
N(2)ϪIrϪN(4)
N(2)ϪIrϪN(3)
C(11)ϪIrϪC(22)
2.057(6)
2.056(5)
2.262(5)
2.217(5)
90.53(19)
104.3(2)
75.44(18)
94.22(19)
81.69(19)
84.6(2)
IrϪC(11)
IrϪC(22)
1.997(6)
2.014(6)
95.5(2)
80.7(2)
93.7(2)
168.6(2)
80.5(3)
93.4(3)
175.0(3)
168.6(2)
C(22)ϪIrϪN(1)
C(22)ϪIrϪN(2)
C(22)ϪIrϪN(3)
C(22)ϪIrϪN(4)
C(11)ϪIrϪN(1)
C(11)ϪIrϪN(2)
C(11)ϪIrϪN(3)
C(11)ϪIrϪN(4)
Scheme 1
1
The H NMR spectrum of complex 3 shows two different
sets of signals for the phenylpyridine ligands. In addition,
the two N-heterocycles of the unsymmetric Me pbpy ligand
2
are clearly distinguishable.
Eur. J. Inorg. Chem. 2005, 110Ϫ117
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
111

K. Kam-Wing Lo, V. Guerchais et al.
FULL PAPER
ligands. This feature has been previously reported for the
above-mentioned monophenylated derivative.[
5g]
Electronic Absorption Spectroscopy
The electronic absorption spectral data for complexes
1
Ϫ4 in CH Cl are summarized in Table 2. All complexes
2 2
display intense absorption bands in the ultraviolet region
at about 250Ϫ300 nm, which are assigned to spin-allowed
1
intraligand IL [π Ǟ π*(ppy and diimine)] transitions. In
the visible region, weak absorption bands at about
3
45Ϫ445 nm are observed; these bands are attributed to
1
spin-allowed MLCT [dπ(Ir) Ǟ π*(ppy and diimine)] tran-
sitions. In addition, weaker absorption bands and tailing
at lower energy, corresponding to spin-forbidden MLCT
3
Figure 2. Emission spectra of complex 1 in CH
ϪϪϪ) and EtOH/MeOH (4:1, v/v) at 77 K (------)
3
3
3
CN at 298 K
CN at 298 K
CN at 298 K
(
[
dπ(Ir) Ǟ π*(ppy and diimine)] transitions, are also ob-
served. The absorption characteristics of these complexes
are similar to those of related cyclometallated polypyridi-
neiridium complexes.[1,5Ϫ8]
Table 2. Electronic absorption spectral data for complexes 1Ϫ4 at
[
a]
298 K
Complex
λ
abs [nm] (ε [mϪ1 cmϪ1])
1
2
3
4
260 (49000), 300 (32000), 345sh (12000), 385sh (5200),
45sh (1600), 480sh (1000)
260 (48000), 300sh (29000), 345sh (12000), 385sh (5600),
45sh (1600), 475sh (900)
260 (32000), 300sh (21000), 335sh (9400), 370sh (6300),
10sh (3700), 465sh (740)
260 (42000), 300sh (21000), 345sh (12000), 380 (6900),
20 (4100), 470 (1000)
4
4
4
4
Figure 3. Emission spectra of complex 2 in CH
(ϪϪϪ) and EtOH/MeOH (4:1, v/v) at 77 K (------)
[
a]
2 2
Data for deoxygenated CH Cl solutions.
Luminescence Properties
Upon photoexcitation, complexes 1Ϫ4 display moder-
ately intense and long-lived orange-yellow to greenish-yel-
low emission under ambient conditions and in low-tem-
perature glass. The emission spectra of complexes 1Ϫ4 in
CH CN at 298 K and alcohol glass at 77 K are shown in
3
Figures 2Ϫ5. The photophysical data are listed in Table 3.
The observed emission lifetimes in the microsecond and
sub-microsecond time scales indicate the phosphorescent
nature of the emission. The emission maxima occur at
higher energy in less-polar CH Cl than in more-polar
2
2
CH CN. This observation is commonly made in other lumi-
3
nescent cyclometallated diiminoiridium systems.[
1,5Ϫ8]
In
view of the low-lying π*-orbitals of the diimine ligands, the
Figure 4. Emission spectra of complex 3 in CH
emission is assigned to an emissive state of predominately
(
ϪϪϪ) and EtOH/MeOH (4:1, v/v) at 77 K (------)
3
MLCT [dπ(Ir) Ǟ π*(diimine)] character. However, the low
reversibility of the oxidation waves of the complexes (see
below) suggests the involvement of covalent IrϪC bond
character in the HOMOs of the complexes. The possibility Nevertheless, more detailed studies such as MO calcu-
3
of a triplet σ-bond-to-ligand SBLCT [σ(IrϪC) Ǟ π*(diim- lations are required to obtain a clearer picture of the elec-
[
5a,7b,7c]
ine)] emissive state thus cannot be totally ignored.
tronic structures and excited-state nature of the complexes.
112
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org Eur. J. Inorg. Chem. 2005, 110Ϫ117

Cyclometallated Iridium(iii) Complexes with Phenylated Bipyridine Ligands
FULL PAPER
3
3
π*-level, and the MLCT/ SBLCT emission occurs at
higher energy than expected. On the other hand, the di-tert-
butyldiphenyl complex 1 (λem ϭ 566 nm) emits at slightly
higher energy than complex 2 (λem ϭ 571 nm), probably
due to the stronger electron-donating properties of the two
tert-butyl substituents on the bipyridine ligand.
It is noteworthy that complex 1 (λem ϭ 566 nm) emits at
significantly higher energy than its phenyl-free counterpart
ϩ
[8]
[
Ir(ppy-C,N) (tBu bpy-N,N)] (581 nm in CH CN). This
2 2 3
observation is in line with the crystal structure of complex
, which reveals that the two additional phenyl rings lower
1
the π-conjugation between the two pyridine rings, and
thereby destabilize the π*-orbitals of the diimine ligand,
3
3
and increase the MLCT/ SBLCT emissive energy.
Upon cooling to 77 K, all four complexes display struc-
tural spectra and hypsochromic shifts in their emission
maxima. These findings are commonly observed in other
related luminescent cyclometallated polypyridineiridium
3
Figure 5. Emission spectra of complex 4 in CH CN at 298 K
(
ϪϪϪ) and EtOH/MeOH (4:1, v/v) at 77 K (------)
The assignment of a 3MLCT/ SBLCT excited state is
3
[
1,5Ϫ8]
complexes.
The emission decay is strictly single-ex-
supported by the observation that the dimethyl complex 4
λem ϭ 573 nm in CH CN at 298 K) emits at noticeably
ponential, with a lifetime of about 4Ϫ5 µs. In general, the
(
3
emission is tentatively assigned to an excited state of pre-
higher energy than the non-substituted bipyridine analogue
3
3
ϩ
[1d]
dominantly MLCT/ SBLCT character.
[
Ir(ppy-N,C) (bpy-N,N)] (λem ϭ 606 nm).
It is likely
2
that the dimethyl substituents of complex 4 destablize the
π*-orbitals of the Me bpy ligand, and thereby increase the
MLCT emission energy. The observation that the dimeth-
2
Electrochemical Properties
3
ylphenyl complex 3 (λem ϭ 585 nm in CH CN at 298 K)
The electrochemical data for complexes 1Ϫ4 are reported
3
emits at lower energy than complex 4 suggests that the phe- in Table 4. The cyclic voltammograms of the complexes in
nyl ring at the 6-position of the bipyridine ligand of com- CH CN solution exhibit a reversible reduction at about
3
ϩ
plex 3 lowers the energy level of the π*-orbitals due to elec- Ϫ1.90 V vs. Fc/Fc . These waves can be assigned to the
tronic effects. Interestingly, the emission of the dimethyldi- reduction of the bipyridine ligand as the cyclometallating
phenyl complex 2 occurs at almost the same energy as the ppy ligand is known to be reduced at much lower potenti-
[
5d,6d]
dimethyl complex 4, even though the former has two ad- al.
The cyclic voltammograms also exhibit an irrevers-
ditional phenyl rings. The presence of two phenyl substitu- ible oxidation wave at a potential between 0.82 and 0.87 V
ϩ
ents in the 6- and 6Ј-positions does not lead to a batho- vs. Fc/Fc . According to previous electrochemical studies
chromic shift as would be expected for a more extended π- on related complexes, these waves are attributed to metal-
III IV
[5a,7b,7c]
conjugated diimine ligand. A possible explanation is that in centered Ir /Ir oxidation processes.
The irrevers-
complex 2, due to steric reasons, the two phenyl rings are ible nature of this process suggests that the HOMOs may
[
5a,7b,7c]
not coplanar with the bpy moiety, and the degree of coplan- involve some covalent σ(IrϪC) character.
By con-
arity of the bipyridine rings is also substantially reduced, as trast, a quasi-reversible oxidation is observed for complex
observed in the solid-state structure of complex 1 (see 4 containing the non-phenylated 4,4Ј-dimethyl-2,2Ј-bipyri-
above). Thus, the lack of extensive π-conjugation raises the dine ligand. It is noteworthy that the same reversible oxi-
Table 3. Photophysical data for complexes 1Ϫ4
Complex[a]
Medium (T [K])
λ
em [nm]
τ
o
[µs]
Φ
em
k
r
[sϪ1
]
k ]
nr [sϪ1
4
4
5
1
CH
CH
glass (77)
3
CN (298)
Cl (298)
566
555
0.69
0.52
4.44
0.12
0.15
4.48
0.18
0.32
3.95
0.49
0.78
4.83
0.0038
0.0070
3.9 ϫ 10
9.0 ϫ 10
7.9 ϫ 10
1.1ϫ 10
6
2
2
[b]
485, 499, 520 sh, 537 sh
571
564
485, 507, 520 sh 547 sh
585
576
482 sh, 517, 547 sh
573
563
4
4
6
2
3
4
CH
CH
3
CN (298)
Cl (298)
0.0076
0.012
6.3 ϫ 10
8.0 ϫ 10
8.3 ϫ 10
6.6 ϫ 10
6
2
2
[b]
glass (77)
5
5
6
6
CH
CH
3
CN (298)
Cl (298)
0.039
0.12
Ϫ
0.16
0.31
2.2 ϫ 10
3.8 ϫ 10
Ϫ
5.3 ϫ 10
2.8 ϫ 10
Ϫ
2
2
[b]
glass (77)
5
6
CH
CH
3
CN (298)
Cl (298)
3.3 ϫ 10
4.0 ϫ 10
1.7 ϫ 10
8.8 ϫ 10
5
5
2
2
[b]
glass (77)
476 sh, 506, 534 sh, 580 sh
[
a]
Data for deoxygenated solutions. [b] EtOH/MeOH (4:1, v/v).
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 110Ϫ117
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
113

K. Kam-Wing Lo, V. Guerchais et al.
FULL PAPER
Table 4. Electrochemical data for complexes 1Ϫ4 in CH
3
CN (0.1 was found to be inefficient, and the precursor dimer was
partially recovered. Moreover, syntheses starting directly
from IrCl ·nH O to prepare the homoleptic complexes were
Ϫ1
m nBu
4
NPF
6
, Pt electrode, scan rate 100 mV·s )
3
2
ϩ
ϩ
Complex
E
p
[V] vs. Fc/Fc
E1/2 [V] vs. Fc/Fc
also unsuccessful whatever the nature of the ligand. The
fact that the bipyridine ligand may adopt a transoid confor-
mation could induce a steric hindrance due to the presence
of a substituent in the 4-position, especially in the case of
the tBu-substituted derivative.
1
2
3
4
0.83[
a]
Ϫ1.91
Ϫ1.8
[b]
[
a]
a]
c]
[b]
0.82
0.87[
0.86[
Ϫ1.89
Ϫ1.90
[b]
[b]
[
a]
Irreversible process. [b] Quasi-reversible wave. [c] Reversible wave.
Concluding Remarks
dation process has recently been reported for the related
In conclusion, we have isolated a new series of lumi-
nescent cyclometallated diiminoiridium(iii) complexes con-
taining substituted bipyridine ligands. Upon photoexcit-
ation, all the complexes are emissive in fluid solutions under
ambient conditions and in low-temperature glass. The emis-
ϩ [8]
complex [Ir(ppy-N,C) (tBu bpy-N,N)] .
2
2
N-Alkylation Reactions and Attempts to Enforce N,C-
Coordination of the Diimine Ligands
3
sion originates from an excited state of MLCT [dπ(Ir) Ǟ
N-Protection by methylation of one pyridine ring of the
above diimine ligands was performed in order to avoid N,N-
coordination. The methylation reactions were performed
with either MeOTf or (Me O)(BF ) as alkylating reagents
3
π*(diimine)] character, perhaps with some SBLCT
[σ(IrϪC) Ǟ π*(diimine)] character. Interestingly, instead of
lowering the emission energy, addition of two phenyl sub-
stituents at the 6- and 6Ј-positions of the bipyridine ligand
increases the emission energy of the complex. It is likely
that the presence of the phenyl rings significantly lowers the
degree of coplanarity of the bipyridine ligand, and thereby
3
4
in a chlorinated solvent. In the case of tBu dpbpy, the reac-
2
tion gives the dialkylated product. The desired monopro-
tected cations were obtained in a pure form after recrystal-
lisation from a CH Cl /diethyl ether mixture as a white
2
2
3
destabilizes the MLCT emissive state. This is in line with
powder in moderate to good yield (36Ϫ56%). It is note-
the tilting of the two pyridine rings observed in the crystal
structure of complex 1. Our next target is to functionalize
the 4,4Ј-dimethyl groups of the bipyridine ligand so that the
complexes can be immobilized on a solid support. Related
work is in progress.
worthy that the monophenylated derivative Me pbpy un-
2
dergoes selective methylation at the non-phenylated pyri-
dine ring, probably due to steric reasons (Scheme 2). Thus,
the phenylpyridine fragment of this compound is accessible
for N,C-coordination. In addition, the N-methyl group can
be readily removed in the presence of DABCO. A second
N,C-coordination could be subsequently envisaged in the
case of the diphenylated derivatives.
Experimental Section
General Procedures: All manipulations were performed using
Schlenk techniques under Ar. All solvents were dried and purified
by standard procedures. All starting materials were used as re-
ceived, MnO
pyridine (dpbpy),
dpbpy) and 4,4Ј-di-tert-butyl-6,6Ј-diphenyl-2,2Ј-bipyridine
2
was purchased from Merck. 6,6Ј-Diphenyl-2,2Ј-bi-
6,6Ј-diphenyl-4,4Ј-dimethyl-2,2Ј-bipyridine
(
(
Me
tBu
2
[
9,10]
2
dpbpy) were prepared according to literature methods.
NMR spectra were recorded with Bruker DPX-200, AV 300 or AV
Scheme 2
1
13
5
00 MHz spectrometers. H and C NMR chemical shifts are
and were determined by reference to residual
H and C solvent signals. Attribution of carbon atoms was based
It is noteworthy that the coordination of pyridinium li- given versus SiMe
4
1
13
gands has not been reported for Ir so far, whereas examples
are known for Ru, Rh, Pt and Pd complexes.[13,14] The
on HMBC, HMQC and COSY experiments. UV/Vis absorption
spectra were recorded using a UVIKON 9413 spectrophotometer,
and emission spectra were measured with a PTI C 60 fluorescence
spectrophotometer. High-resolution mass spectra (HRMS) were
performed with an MS/MS ZABSpec TOF at the CRMPO (Centre
de Mesures Physiques de l’Ouest) in Rennes. Elemental analyses
were performed by the Service central d’analyse du CNRS at Ver-
naison. Cyclic voltammograms were recorded using a PAR model
classical procedures reported for the preparation of fac-tris-
(cyclometallated) complexes have been applied for the cat-
[
2]
ionic ligands. The dimer [Ir(ppy-N,C) (µ-Cl)] and [N-
2
2
ϩ
Me -Me pbpy](OTf) were refluxed at 200°C in glycerol in
2
the presence of Na CO (Scheme 3). However, this route
2
3
273 Autolab. The working electrode was polished Pt, the counter-
electrode was a Pt wire, and a saturated calomel electrode (SCE)
ϩ
was used as the reference electrode. The Cp
2 2
Fe/Cp Fe redox cou-
ple was used as a secondary internal reference. Luminescence quan-
[
15]
tum yields were measured by the optically dilute method
using
[
16]
an aerated aqueous solution of [Ru(bpy) ]Cl (Φem ϭ 0.028) as
3
2
the standard solution. Low-temperature (77 K) glass photophysical
measurements were performed with the sample loaded in a quartz
Scheme 3
14
1
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 110Ϫ117

Cyclometallated Iridium(iii) Complexes with Phenylated Bipyridine Ligands
FULL PAPER
ϩ
tube inside a quartz-walled Dewar flask filled with liquid nitrogen.
The excitation source for emission lifetime measurements was the
(tBu) ppm; Py* ϭ Ph-Py. HRMS: m/z ϭ 921.3510 [M] ; calcd. for
1
93
C
52
H
48
N
4
Ir 921.3512.
(Me dpbpy-N,N)](PF
300 MHz, CD COCD ): δ ϭ 8.61 (dd, J ϭ 5.8, J ϭ 0.6 Hz, 2
355 nm output (third harmonic) of a Quanta-Ray Q-switched
[Ir(ppy-N,C)
2
2
) (2): Yield 80%. 1H NMR
6
GCR-150-10 pulsed Nd-YAG laser. Luminescence decay signals
from a Hamamatsu R928 photomultiplier tube were converted into
potential changes by a 50 Ω load resistor and then recorded with
a Tektronix Model TDS 620A digital oscilloscope.
3
4
(
3
3
6
4
3
3
H, H -Py), 8.57 (d, J ϭ 1 Hz, 2 H, H -Py*), 7.95 (td, J ϭ 8.3,
3
4
4
3
4
J ϭ 7.6, J ϭ 0.6 Hz, 2 H, H -Py), 7.85 (dd, J ϭ 7.6, J ϭ 1.5 Hz,
3
3
3
4
5
2
H, H -Py), 7.28 (td, J ϭ 8.3, J ϭ 5.8, J ϭ 1.5 Hz, 2 H, H -
4
5
3
4
Py), 7.25 (d, J ϭ 1 Hz, 2 H, H -Py*), 7.19 (dd, J ϭ 7.8, J ϭ
4
(
,4Ј-Di-tert-butyl-6,6Ј-diphenyl-2,2Јbipyridine (tBu
11 mL, 20 mmol; 1.8 m, cyclohexane/diethyl ether) was added to
a solution of 4,4Ј-di-tert-butyl-2,2Ј-bipyridine (1.34 g, 5 mmol) in
0 mL of THF. After stirring at room temperature for 30 min, the
reaction medium was refluxed for 12 h. The reaction mixture was
then hydrolysed at 0°C and the residue extracted with CH Cl (3
ϫ 150 mL). The organic phase was dried with MgSO and MnO
12.5 g, 144 mmol) was added. The reaction medium was stirred
2
dpbpy): PhLi
3
1.3 Hz, 2 H, H -Ph), 6.98 (m, 2 H, Ph* para), 6.71 (m, 4 H, Ph*
3
4
4
ortho and meta), 6.45 (td, J ϭ 7.8, J ϭ 0.7 Hz, 2 H, H -Ph), 6.11
3
4
5
3
4
(
td, J ϭ 7.8, J ϭ 1.3 Hz, 2 H, H -Ph), 5.25 (dd, J ϭ 7.8, J ϭ
2
6
13
1
0.7 Hz, 2 H, H -Ph), 2.57 (s, 6 H, Me) ppm. C { H} NMR
2
6
2
(
3 3
75.4 MHz, CD COCD ): 168.1 (C -Py), 164.4 (C -Py*), 159.1 (C -
2
2
4
6
1
2
Py*), 151.5 (C -Py*), 150.9 (C -Py), 147.2 (C -Ph), 141.9 (C -Ph),
4
2
4
6
5
138.6 (Ph* ipso), 138.0 (C -Py), 130.7 (C -Ph), 130.1 (C -Py*),
(
5
129.1 (C -Ph), 127.9 (Ph para), 127.4 (Ph* ortho/meta), 127.3 (Ph*
for 12 h and then filtered through Celite. Chromatography on silica
gel (heptane/ethyl acetate, 95:5) afforded a white powder (1.34 g,
3
3
5
ortho/meta), 125.2 (C -Py*), 123.9 (C -Ph), 122.1 (C -Py), 120.4
4
3
1
4
(C -Ph), 119.3 (C -Py). 20.9 (Me) ppm; Py* ϭ Ph-Py. HRMS:
3
84%). H NMR (200 MHz, CDCl ): δ ϭ 8.61 (d, J ϭ 1.8 Hz, 2
ϩ
193
3/5
4
m/z
46 36 4
ϭ 837.2574 [M] ; calcd. for C H N Ir 837.2572.
H, H -Py), 8.17 (m, 4 H, Ph ortho), 7.78 (d, J ϭ 1.8 Hz, 2 H,
3
/5
C H F IrN P (982.0): calcd. C 56.26, H 3.70, N 5.71; found C
H
-Py), 7.50 (m, 6 H, Ph meta and para), 1.47 (s, 18 H, tBu) ppm.
46 36
6
4
13
1
2/6
56.32, H 4.06, N 5.62.
Ir(ppy-N,C) (Me pbpy-N,N)](PF
300 MHz, CD COCD
C { H} NMR (75.4 MHz, CDCl
3
): δ ϭ 162.0 (C -Py), 156.9
-Py), 140.6 (C -Py), 129.2 (Ph), 128.8 (Ph), 127.6 (Ph), 127.0
2
/6
4
(
(
C
(3): Yield 80%. 1H NMR
[
2
2
6
)
3/5
3/5
Ph), 118.0 (C -Py), 117.4 (C -Py), 35.7 (tBu), 31.2 (tBu).
3
(
3
3
): δ ϭ 8.78 (s, 1 H, H -Py*), 8.75 (s, 1 H,
ϩ
HRMS: m/z ϭ 420.2563 [M] ; calcd. for C30
(420.6): calcd. C 85.67, H 7.67, N 6.66; found C 85.05,
H 7.94, N 6.27.
H
32
N
2
420.25655.
3
3
3
4/6
H -Py), 8.09 (m, 2 H, H -PyA, H -PyB), 8.00 (m, 2 H, H -PyB),
C
30
H
32
N
2
4/6
3
6
7
.91 (m, 2 H, H -PyA), 7.76 (d, J ϭ 5.7 Hz, 1 H, H -Py), 7.68
3
4
3
5
(dd, J ϭ 7.8, J ϭ 1.2 Hz, 1 H, H -PhA), 7.41 (m, 2 H, H -Py,
5
4
3
3
H -Py*), 7.37 (dd, J ϭ 1.3, J ϭ 7.8 Hz, 1 H, H -PhB), 7.26 (td,
4,4Ј-Dimethyl-6-phenyl-2,2Ј-bipyridine (Me
2
pbpy): The monopheny-
3
3
4
5
4
J ϭ 5.9, J ϭ 7.8, J ϭ 1.4 Hz, 1 H, H -PyA), 7.19 (td, J ϭ 1.6,
J ϭ 5.9, J ϭ 7.8 Hz, 1 H, H -PyB), 6.92 (m, J ϭ 1.2, J ϭ
lated derivative 4,4Ј-dimethyl-6-phenyl-2,2Ј-bipyridine was ob-
3
3
5
4
3
9]
tained during the preparation of Me
silica gel using ethyl acetate as eluent gave pure Me
2
dpbpy.[ Chromatography on
pbpy as a white
COCD ): δ ϭ 8.51
d, J ϭ 4.8 Hz, 1 H, H -Py), 8.49 (d, J ϭ 1.2 Hz, 1 H, H -Py),
4
5
7
6
.8 Hz, 2H, H -PhA, Ph para), 6.78 (m, 3 H, H -PhA, Ph meta),
.66 (m, 2 H, Ph ortho), 6.54 (td, J ϭ 7.6, J ϭ 1.2 Hz, 2 H, H -
2
3
4
4
1
powder. Yield: 46%. H NMR (200 MHz, CD
(
3
3
3
4
5
4
PhB), 6.33 (td, J ϭ 7.6, J ϭ 1.3 Hz, 1 H, H -PhB), 6.00 (dd, J ϭ
3
6
4
3
3
6
3
4
1
.2, J ϭ 7.6 Hz, 1 H, H -PhA), 5.63 (dd, J ϭ 7.7, J ϭ 1.2 Hz, 1
3
/5
4
8
H
.22 (m, 3 H, H -Py* and Ph ortho), 7.79 (d, J ϭ 1.8 Hz, 1 H,
6
13
H, H -PhB), 2.67 (s, 3 H, Me-Py*), 2.57 (s, 3 H, Me-Py) ppm.
H} NMR (75.4 MHz, CD COCD ): 169.0 (C -PyB), 167.2 (C -
3 3
C
3/5
3
4
-Py*), 7.52 (m, 3 H, Ph), 7.22 (dd, J ϭ 4.8, J ϭ 1.2 Hz, 1 H,
1
2
2
{
5
H -Py), 2.50 (s, 3 H, MePy*), 2.48 (s, 3 H, MePy) ppm; (Py* ϭ Ph-
Py). HRMS: m/z ϭ 260.1328 [M] ; calcd. for C18
C H N
18 16 2
H 6.33, N 10.10.
6
2
2
4
PyA), 164.9 (C -Py*), 156.9 (C -Py), 156.7 (C -Py*), 152.0 (C -Py*),
ϩ
16 2
H N 260.13135.
4
1
6
6
6
1
1
1
1
1
1
1
2
7
51.7 (C -Py, C -PhB), 149.8 (C -PyA), 149.3 (C -PyB, C -Py),
47.3 (C -PhA), 143.4 (C -PhA), 143.2 (C -PyB), 138.5 (C -PyA),
38.3 (Ph ipso), 138.2 (C -PyB), 131.4 (C -PhB), 130.5 (C -Py*),
30.3 (C -PhA), 130.2 (C -PhA), 129.0 (C -PyB), 128.6 (Ph para),
28.4 (C -Py), 127.6 (Ph meta), 127.4 (Ph ortho), 125.9 (C -Py),
24.6 (C -Py*), 124.5 (C -PhA), 124.4 (C -PhB), 123.6 (C -PyA),
22.5 (C -PyB), 120.2 (C -PhB), 119.9 (C -PyB), 119.7 (C -PyA),
0.4 (Me-Py), 20.1 (Me-Py*) ppm; Py* ϭ Ph-Py. HRMS: m/z ϭ
(260.3): calcd. C 83.04, H 6.19, N 10.76; found C 82.93,
1
2
2
4
4
6
5
5
6
5
Synthesis of [Ir(ppy-N,C)
2
(L-N,N)](PF
(µ-Cl)] (0.1 mmol), the appropriate bi-
pyridine derivative L (0.2 mmol), and AgPF (0.2 mmol) were
6
) (1؊4): The chloride-
5
3
bridged dimer [Ir(ppy-N,C)
2
2
3
3
3
5
6
5
4
3
3
mixed in 1,2-dichloroethane (10 mL). The reaction mixture was re-
fluxed under Ar for 2 h. The solution was then concentrated to
dryness and the product was extracted with CH
ϩ
193
61.2268 [M] ; calcd. for C40
H
32
N
4
Ir 761.2259.
2
Cl
2
(3 ϫ 5 mL).
Crystallisation from a CH
green powder.
2 2
Cl /diethyl ether mixture gave a yellow-
(4): Yield 80%. 1H NMR
[
(
8
Ir(ppy-N,C)
300 MHz, CD
2
(Me
2
bpy-N,N)](PF
6
)
3
3
3
3
3
COCD ): δ ϭ 8.74 (s, 2 H, H -Py*), 8.27 (d, J ϭ
3
4
.1 Hz, 2 H, H -Py*), 7.97 (m, 4 H, H -Ph, H -Py), 7.86 (m, 4 H,
[
(
Ir(ppy-N,C)
2
(tBu
2
dpbpy-N,N)](PF
): δ ϭ 8.65 (dd, J ϭ 5.8, J ϭ 1.4 Hz, 2
) (1): Yield 76%. 1H NMR
6
6
6
3
5
3
H -Py*, H -Py), 7.50 (d, J ϭ 6.2 Hz, 2 H, H -Py*), 7.19 (td, J ϭ
3
4
300 MHz, CD
3
COCD
3
3
4
5
3
4
5
0
6
.8, J ϭ 7.2, J ϭ 1.1 Hz, 2 H, H -Py), 7.05 (td, J ϭ 7.4, J ϭ
.8 Hz, 2 H, H -Ph), 6.94 (td, J ϭ 7.4, J ϭ 1.2 Hz, 2 H, H -Ph),
.38 (dd, J ϭ 7.4, J ϭ 0.8 Hz, 2 H, H -Ph), 2.59 (s, 6 H, Me)
6
4
3
3
H, H -Py), 8.60 (d, J ϭ 2.0 Hz, 2 H, H -Py*), 7.96 (td, J ϭ 8.2,
4
3
4
5
4
4
3
4
J ϭ 1.4 Hz, 2 H, H -Py), 7.86 (dd, J ϭ 8.2, J ϭ 1.5 Hz, 2 H,
3
4
6
3
4
5
3
3
H -Py), 7.42 (d, J ϭ 2.0 Hz, 2 H, H -Py*), 7.26 (td, J ϭ 8.2, J ϭ
5
H, H -Ph), 6.99 (m, 2 H, Ph* para), 6.76 (m, 8 H, Ph* meta and
ortho), 6.48 (td, J ϭ 7.7, J ϭ 0.8 Hz, 2 H, H -Ph), 6.13 (td, J ϭ
1
3
1
2
ppm. C { H} NMR (75.4 MHz, CD
3
COCD
3
): δ ϭ 167.6 (C -Py),
4
5
3
4
.8, J ϭ 1.5 Hz, 2 H, H -Py), 7.21 (dd, J ϭ 7.7, J ϭ 1.2 Hz, 2
2
4
1
6
1
1
(
55.7 (C -Py*), 152.1 (C -Py*), 149.8 (C -Ph), 149.7 (C -Py*),
49.2 (C -Py), 144.3 (C -Ph), 138.7 (C -Py), 131.0 (C -Ph), 130.4
C -Ph), 129.1 (C -Py*), 125.6 (C -Py*), 125.1 (C -Ph), 123.7 (C -
3
6
2
4
6
3
4
4
3
5
5
3
3
5
4
5
3
4
7
.7, J ϭ 1.2 Hz, 2 H, H -Ph), 5.29 (dd, J ϭ 7.7, J ϭ 0.8 Hz, 2
4
3
Py), 122.6 (C -Ph),120.0 (C -Py), 20.4 (Me) ppm. HRMS: m/z ϭ
6
13
1
H, H -Ph), 1.43 (s, 18 H, tBu) ppm. C { H} NMR (75.4 MHz,
ϩ
193
6
(
85.1939 [M] ; calcd. for C34
829.8): calcd. C 49.50, H 3.68, N 6.64; found C 49.21, H 3.40,
N 6.75.
H
28
N
4
28 6 4
Ir 685.1945. C34H F IrN P
2
4
6
3 3
CD COCD ): δ ϭ 168.0 (C -Py), 163.9 (C -Py*, C -Py*), 160.1
2
6
1
2
(
C -Py*), 150.8 (C -Py), 146.8 (C -Ph), 141.9 (C -Ph), 138.6 (Ph*
4
6
5
ipso), 138.1 (C -Py), 130.8 (C -Ph), 129.1 (C -Ph), 128.0 (Ph* para),
5
3
1
27.4 (Ph* ortho and meta), 125.8 (C -Py*), 124.1 (C -Ph), 121.7 4,4Ј-Di-tert-butyl-1-methyl-6,6Ј-diphenyl-2,2Ј-bipyridinium
Tetra-
5
3
4
3
(C -Py, C -Py*), 120.5 (C -Ph), 119.1 (C -Py), 35.4 (tBu), 29.4 fluoroborate: [Me
3
O][BF
4
] (97 mg, 0.66 mmol) was added to a solu-
Eur. J. Inorg. Chem. 2005, 110Ϫ117
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
115

K. Kam-Wing Lo, V. Guerchais et al.
Cl. 0.46 mmol) were added to a solution of [Ir(ppy-N,C) (µ-Cl)]
FULL PAPER
tion of tBu
After refluxing for 15 h, the solution was concentrated to dryness.
The residue was crystallized from a CH Cl /diethyl ether mixture
2
dpbpy (250 mg, 0.60 mmol) in 10 mL of ClCH
2
CH
2
2
2
(50 mg, 0.046 mmol) in 10 mL of glycerol. The reaction mixture
was then heated to 200 °C for 24 h. Addition of water (10 mL) gave
a brown precipitate, which was washed with diethyl ether (2 ϫ
2
2
in order to separate the N,N-dimethyl adduct and the diimine pre-
cursor. The product was isolated as a white powder by concen-
1
5 mL) and methanol (5 mL). H NMR studies of the crude product
1
tration of the resulting solution (112 mg, 36%).
H
NMR
showed the presence of the dimer precursor and an unidentified
4
3
(
8
1
3 3
300 MHz, CD COCD ): δ ϭ 8.40 (d, J ϭ 2.3 Hz, 1 H, H -Py*), product.
5
5
4
.28Ϫ8.22 (m, 4 H, H -Py*, H -Py, Ph ortho), 8.05 (d, J ϭ 1.4 Hz,
H, H -Py), 7.90Ϫ7.85 (m, 2 H, Ph* ortho), 7.76Ϫ7.66 (m, 3 H,
3
Structural Determination of Complex 1: Single crystals for X-ray
diffraction studies were grown by slow diffusion of diethyl ether
Ph* meta and para), 7.59Ϫ7.50 (m, 3 H, Ph meta and para), 4.13
1
3
into a CH
studied with a NONIUS Kappa CCD with graphite-monochrom-
ated Mo-K radiation. The data collection and refinement param-
eters are presented in Table 5. The structures were solved with SIR-
2 2
Cl solution of complex 1 at 20 °C. The samples were
(
{
(
s, 3 H, N-Me), 1.57 (s, 9 H, tBu*), 1.50 (s, 9 H, tBu) ppm.
C
1
4
3 3
H} NMR (75.4 MHz, CD COCD ): δ ϭ 170.6 (C -Py*), 163.4
4
6
6
2
2
α
C -Py), 157.4 (C -Py), 156.9 (C -Py*), 154.7 (C -Py*), 151.3 (C -
Py), 138.4 (Ph ipso), 133.3 (Ph* ipso), 131.2 (Ph*), 129.8 (Ph), 129.6
Ph*), 129.4 (Ph*), 128.9 (Ph), 127.3 (Ph), 126.8 (C -Py*), 126.1
C -Py*), 121.8 (C -Py), 119.1 (C -Py), 45.0 (N-Me), 36.6 (tBu*),
5.4 (tBu), 29.8 (tBu), 29.2 (tBu*) ppm; Py* ϭ N-MePy. HRMS:
97,[
17a]
which reveals the non-hydrogen atoms of the molecules. The
5
(
(
3
3
5
whole structures were refined by full-matrix, least-squares tech-
2
niques on F , with hydrogen atoms refined using the riding mode.
3
ϩ
Structures were solved by Patterson or direct methods. The struc-
tures were completed by subsequent difference Fourier techniques
m/z ϭ 435.2784 [M] ; calcd. for C31
,4,4Ј-Trimethyl-6,6Ј-diphenyl-2,2Ј-bipyridinium Triflate: Me
0.25 g, 0.74 mmol) was dissolved in 5 mL of ClCH CH Cl in a
35 2
H N 435.2800.
1
(
2
dpbpy
2
and refined by full-matrix least squares on F (SHELXL-97) with
[17]
2
2
initial isotropic parameters.
CCDC-225743 contains the sup-
Schlenk tube and MeOTf (83 µL, 0.74 mmol) was then added. The
reaction mixture was stirred overnight and the solvent evaporated.
The residue was extracted with 5 mL of CH Cl . Addition of di-
2 2
ethyl ether precipitated the precursor compound; the monocation
plementary crystallographic data for this paper. These data can be
obtained free of charge at www.ccdc.cam.ac.uk/conts/retriev-
ing.html [of from Cambridge Crystallographic Data Centre, 12 Un-
ion Road, Cambridge CB2 1EZ; Fax: ϩ 44-1223-336-033; E-mail:
deposit@ccdc.cam.ac.uk].
was then recovered as a white powder (176 mg, 48%) upon evapor-
1
ation of the resulting solution. H NMR (300 MHz, CD
3
COCD
3
):
4
3
δ ϭ 8.27 (d, J ϭ 1.9 Hz, 1 H, H -Py*), 8.22 (m, 2 H, Ph*), 8.13
m, 2 H, H -Py, H -Py*), 7.88 (m, 3 H, Ph ortho, H -Py), 7.75 (m,
Table 5. Crystallographic data and refinement for complex 1
5
5
3
(
3
H, Ph meta and para), 7.55 (m, 3 H, Ph* meta and para), 4.22
Empirical formula
Formula mass
Crystal system
52 51 6 4
C H F N IrO1.5P
1
3
(
{
s, 3 H, N-Me), 2.85 (s, 3 H, Me*), 2.62 (s, 3 H, Me) ppm.
C
1093.14
orthorhombic
P2
1
4
H} NMR (75.4 MHz, CD
3
COCD
3
2
): δ ϭ 159.4 (C -Py*), 156.7
6
2
4
6
(
C -Py*), 154.0 (C -Py*), 150.8 (C -Py, C -Py), 150.4 (C -Py), Space group
1 1 1
2 2
5
˚
1
1
1
2
38.9 (Ph* ipso), 133.0 (Ph ipso), 131.4 (Ph para), 130.3 (C -Py*),
a [A]
13.3214(2)
17.4083(3)
25.0454(3)
4936.1(1)
4
1.471
2196
0.71073
2.48Ϫ27.50
11257
11257
9931
˚
3
b [A]
29.8 (Ph*), 129.6 (C -Py*), 129.4 (Ph), 129.2 (Ph), 128.9 (Ph*),
˚
3
5
c [A]
27.1 (Ph*), 125.3 (C -Py), 122.8 (C -Py), 45.2 (N-Me), 20.9 (Me*),
˚
3
V [A ]
ϩ
0.4 (Me) ppm; Py* ϭ N-MePy. HRMS: m/z ϭ 351.1858 [M] ;
Z
D
calcd. for C25
,4,4Ј-Trimethyl-6Ј-phenyl-2,2Ј-bipyridinium Triflate: Me
0.10 g, 0.38 mmol) was dissolved in 5 mL of CHCl in a Schlenk
tube. The solution was cooled to Ϫ30°C and MeOTf (43 µL,
.38 mmol) was then added. The reaction mixture was warmed up
H
23
N
2
351.18612.
calcd. [g/cm3]
F(000)
λ(Mo-K
1
(
2
pbpy
˚
α
) [A]
3
θ range [°]
No. of reflections collected
No. of unique reflections
No. of observed reflections [I Ͼ 2σ(I)]
No. of parameters
0
to room temperature and the solvent evaporated. The residue was
washed with toluene (2 ϫ 3 mL) and the residue extracted with
5
then concentrated to afford a white powder (90 mg, 56%).
NMR (200 MHz, CD
Py), 8.24 (d, J ϭ 1.8 Hz, 1 H, H -Py), 8.17 (d, J ϭ 1.6 Hz, 1 H,
H
596
1.023
0.044, 0.112
2.4, Ϫ1.126
2
mL of CHCl
3
. The solution was cooled to Ϫ20°C, filtered, and
Goodness of fit on F
1
H
Final R, Rw
3
6
∆ρmax,min [e·AϪ3]
˚
3
COCD
3
): δ ϭ 9.05 (d, J ϭ 6.6 Hz, 1 H, H -
4
3
4
3
/5
3
3
3
4
-Py*), 8.16 (t, J ϭ 6.0 Hz, 2 H, Ph ), 8.12 (dd, J ϭ 6.6, J ϭ
5
4
3/5
1
.8 Hz, 1 H, H -Py), 7.78 (d, J ϭ 1.6 Hz, 1 H, H -Py*), 7.52 (td,
3
4
4
3
4
J ϭ 6.0, J ϭ 1.8 Hz, 1 H, Ph ), 7.49 (dd, J ϭ 6.0, J ϭ 1.8 Hz, Acknowledgments
2
1
H, Ph ), 4.52 (s, 3 H, N-Me), 2.80 (s, 3 H, MePy), 2.60 (s, 3 H,
M. L. thanks the R e´ gion Bretagne for a grant. We also thank Prof.
Vivian W. W. Yam of the University of Hong Kong for access to
equipment for photophysical measurements.
ϩ
MePy*) ppm; Py* ϭ N-MePy. HRMS: m/z ϭ 275.1553 [M] ;
calcd. for C19H N 275.1548.
19 2
Deprotection of 1,4,4Ј-Trimethyl-6,6Ј-diphenyl-2,2Ј-bipyridinium
Triflate: A solution of the salt (120 mg, 0.18 mmol) and DABCO
[1] [1a]
R. J. Watts, Inorg. Chem. 1981, 20, 2302. [1b] S. Sprouse, K.
(
20 mg, 0.18 mmol) in 20 mL of DMF was refluxed for 2 h. After
addition of 30 mL of water, the product was extracted with CH Cl
2 ϫ 20 mL). The organic phase was dried with MgSO . Evapor-
ation of the solvent gave a white powder (50 mg, 82%) which was
A. King, P. J. Spellane, R. J. Watts, J. Am. Chem. Soc. 1984,
106, 6647. [ Y. Ohsawa, S. Sprouse, K. A. King, M. K. DeAr-
mond, K. W. Hanck, R. J. Watts, J. Phys. Chem. 1987, 91, 1047.
1c]
2
2
(
4
[1d]
F. O. Garces, K. A. King, R. J. Watts, Inorg. Chem. 1988,
[1e]
1
27, 3464.
A. P. Wilde, R. J. Watts, J. Phys. Chem. 1991, 95,
identified by H NMR spectroscopy as Me
Attempts at N,C-Coordination: 1,4,4Ј-Trimethyl-6Ј-phenyl-2,2Ј-bi-
pyridinium triflate (49 mg, 0.116 mmol) and Na CO (49 mg,
2
dpbpy.
22. [ A. P. Wilde, K. A. King, R. J. Watts, J. Phys. Chem.
1f]
6
[1g]
1991, 95, 629.
G. Carslon, R. J. Watts, Inorg. Chem. 1991, 30, 1685.
K. Dedeiean, P. I. Djurovich, F. O. Garces,
[
1h]
2
3
P. I .
116
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Eur. J. Inorg. Chem. 2005, 110Ϫ117

Cyclometallated Iridium(iii) Complexes with Phenylated Bipyridine Ligands
FULL PAPER
E. A. Plummer, J. W. Hofstraat, L. De Cola, Dalton Trans.
Djurovich, R. J. Watts, Inorg. Chem. 1993, 32, 4681. [ B.
Schmid, F. O. Garces, R. J. Watts, Inorg. Chem. 1994, 33, 9. [
M. G. Colombo, T. C. Brunold, T. Riedner, H. U. Güdel, M.
Förtsch, H.-B. Bürgi, Inorg. Chem. 1994, 33, 545.
2] [2a]
1i]
[7] [7a]
1j]
[7b]
2003, 2080.
P. Didier, I. Ortmans, A. Kirsh-De Mesmaeker,
[7c]
R. J. Watts, Inorg. Chem. 1993, 32, 5239.
M. Polson, S.
Fracasso, V. Bertolasi, M. Ravaglia, F. Scandola, Inorg. Chem.
2004, 43, 1950.
8]
[
S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq,
H. E. Lee, C. Adachi, P. E. Burrows, S. R. Forrest, M. E.
Thompson, J. Am. Chem. Soc. 2001, 123, 4304. [2b] S. Laman-
sky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, R. Kwong, I.
Tsyba, M. Bortz, B. Mui, R. Bau, M. E. Thompson, Inorg.
Chem. 2001, 40, 1704. [ R. Gao, D. G. Ho, B. Hernandez,
M. Selke, D. Murphy, P. L. Djurovich, J. Am. Chem. Soc. 2002,
[
Such a cationic N,N-complex was used recently as a multifunc-
tional chromophore for single-layer electroluminescent devices:
J. D. Slinker, A. A. Gorodetsky, M. S. Lowry, J. Wang, S.
Parker, R. Rohl, S. Bernhard, G. G. Malliaras, J. Am. Chem.
Soc. 2004, 126, 2763.
2c]
[
9] [9a]
C. O. Dietrich-Buchecker, P. A. Marnot, J. P. Sauvage,
Tetrahedron Lett. 1982, 23, 5291. [ C. Kaes, M. W. Hosseini,
A. De Cian, J. Fisher, Tetrahedron Lett. 1997, 38, 4389.
[10] [10a]
9b]
1
24, 14828.
[
[
3] [3a]
M. A. Baldo, M. E. Thompson, S. R. Forrest, Nature 2000,
[
3b]
4
03.
T. Watanabe, K. Nakamura, S. Kawami, Y. Fukuda,
T. Ben Hadda, I. Zidane, S. A. M. Moya, H. Le Bozec,
Polyhedron 1996, 15, 1571. [
10b]
T. Ben Hadda, State Doctorate,
T. Tsuji, T. Wakimoto, S. Miyaguchi, M. Yahiro, M. J. Yang,
[
3c]
T. Tsutsui, Synth. Met. 2001, 122, 203.
R. Robinson, A. J. Heeger, G. C. Bazan, Chem. Commun.
002, 784.
J. C. Ostrowski, M.
University of Mohamed 1st, Oujda, Morocco, 1995.
M. Nonoyama, Bull. Chem. Soc. Jpn. 1974, 47, 767.
[
[
11]
12] [12a]
2
R. Urban, R. Krämer, S. Mihan, K. Polborn, B. Wagner,
4] [4a]
[12b]
V. V. Grushin, N. Herron, D. D. LeCloux, W. J. Marshall,
W. Beck, J. Organomet. Chem. 1996, 517, 191.
J. H. van
A. Petrov, Y. Wang, Chem. Commun. 2001, 1494. [ H. Z. Xie,
M. W. Liu, O. Y. Wang, X. H. Zhang, C. S. Lee, L. S. Hung,
S. T. Lee, P. F. Teng, H. L. Kwong, H. Zhen, C. M. Che, Adv.
Mater. 2001, 13, 1245. [ J.-P. Duan, P.-P. Sun, C.-H. Cheng,
Adv. Mater. 2003, 15, 224. [ T. Tsuzuki, N. Shirasawa, T.
Suzuki, S. Tokito, Adv. Mater. 2003, 15, 1455. [ I. R. Laskar,
T.-M. Chen, Chem. Mater. 2004, 16, 111.
4b]
Diemen, J. G. Haasnoot, R. Hage, E. Müller, J. Reedjik, Inorg.
Chim. Acta 1991, 181, 245.
[13]
For examples of N-methylation of nitrogen ligands, see, inter
4c]
[13a]
alia:
S. Serroni, G. Denti, Inorg. Chem. 1992, 31, 4251.
J.-M. Lehn, J.-P. Sauvage, J. Simon, R. Ziessel, C. Piccini-
4d]
[13b]
4e]
Leopardi, G. Germain, J.-P. Declercq, M. Van Meerssche,
Nouv. J. Chim. 1983, 7, 413. [
13c]
F. L. Wimmer, S. Wimmer,
F. L. Wimmer, S. Wimmer, J.
[
5] [5a]
[13d]
S. Serroni, A. Juris, S. Campagna, M. Venturi, G. Denti, V.
Balzani, J. Am. Chem. Soc. 1994, 116, 9086. [5b] G. Calogero,
G. Giuffrida, S. Serroni, V. Ricevuto, S. Campagna, Inorg.
Chem. 1995, 34, 541. [ A. Mamo, I. Stefio, M. F. Parisi, A.
Credi, M. Venturi, C. Di Pietro, S. Campagna, Inorg. Chem.
Polyhedron 1985, 4, 1665.
Chem. Soc., Dalton Trans. 1994, 879.
[
[
14]
15]
S. Campagna, G. Denti, S. Serroni, A. Juris, M. Venturi, V.
Ricetto, V. Balzani, Chem. Eur. J. 1995, 1, 211.
J. N. Demas, G. A. Crosby, J. Phys. Chem. 1971, 75, 991.
K. Nakamaru, Bull. Chem. Soc. Jpn. 1982, 55, 2697.
5c]
[
5d]
[16]
[17] [17a]
1
997, 36, 5947.
roni, Inorg. Chem. 1999, 38, 2250.
iseau, F. Puntoriero, S. Serroni, S. Campagna, Chem. Commun.
F. Neve, A. Crispini, S. Campagna, S. Ser-
[5e]
P. M. Griffiths, F. Lo-
A. Altomare, M. C Burla, M. Camalli, G. Cascarano, C.
Giacovazzo, A. Guagliardi, A. G. G Moliterni, G. Polidori, R.
[
5f]
[17b]
2000, 2297.
F. Neve, A. Crispini, F. Loiseau, S. Campagna,
Spagna, J. Appl. Crystallogr. 1998, 31, 74Ϫ77.
rick, SHELX97-2, Program for Crystal Structure Refinement,
Göttingen, Germany, 1997.
Crystallography, vol. C (Ed.: A. J. C. Wilson), Kluwer Aca-
demic Publishers, Dordrecht, 1992.
A Multipurpose Crystallographic Tool, Utrecht University,
Utrecht, The Netherlands. 1998.
Received May 19, 2004
G. Sheld-
[
5g]
J. Chem. Soc., Dalton Trans. 2000, 1399.
F. Neve, A. Cris-
pini, Eur. J. Inorg. Chem. 2000, 1039. [ F. Neve, A. Crispini, S.
5h]
[17c]
International Tables for X-ray
Serroni, F. Loiseau, S. Campagna, Inorg. Chem. 2001, 40, 1093.
[
6] [6a]
[17d]
K. K.-W. Lo, D. C.-M. Ng, C.-K. Chung, Organometallics
A. Spek, L. PLATON,
[
6b]
2001, 20, 4999.
K. K.-W. Lo, C.-K. Chung, D. C.-M. Ng,
[
6c]
N. Zhu, New J. Chem. 2002, 26, 81.
K. K.-W. Lo, C.-K.
Chung, D. C.-M. Ng, N. Zhu, Chem. Eur. J. 2003, 9, 475. [
K. K.-W. Lo, C.-K. Chung, T. K.-M. Lee, L.-H. Lui, K. H.-
K. Tsang, N. Zhu, Inorg. Chem. 2003, 42, 6886.
6d]
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