Iridium(III) complexes with sulfonyl and fluorine substituents: Synthesis, stereochemistry and effect of functionalisation on their photophysical properties

Article abstract of DOI:10.1002/chem.200801270

The synthesis and photophysical and electrochemical characterisation of new heteroleptic iridium complexes with electron-withdrawing sulfonyl groups and fluorine atoms bound to phenylpyridine ligands are reported. The emission energy of these materials st

Full text of DOI:10.1002/chem.200801270

DOI: 10.1002/chem.200801270
IridiumACHTUNGTRENNUNG(III) Complexes with Sulfonyl and Fluorine Substituents: Synthesis,
Stereochemistry and Effect of Functionalisation on their Photophysical
Properties
Roberta Ragni,[a] Enrico Orselli,[b, c] Gregg S. Kottas,[b, c] Omar Hassan Omar,[d]
Francesco Babudri,[a, d] Adriana Pedone,[a] Francesco Naso,[a, d]
Gianluca M. Farinola,*[a] and Luisa De Cola*[b, c]
This paper is dedicated to Professor Jan Reedijk on the occasion of his 65th birthday
Abstract: The synthesis and photophys-
ical and electrochemical characterisa-
tion of new heteroleptic iridium com-
plexes with electron-withdrawing sulfo-
nyl groups and fluorine atoms bound
to phenylpyridine ligands are reported.
The emission energy of these materials
strongly depends on the position of the
sulfonyl groups and on the number of
fluorine substituents. A 90 nm wide
tuning range of photoluminescence
from the blue-green (lem =468 nm)
the orange (lem =558 nm) of iridi-
um(III)bis[2-(3’-benzylsulfonyl)phenyl-
pyridinato-N,C2’](2,4-decanedionate)
has been achieved. Emission quantum
yields ranging from 47 to 71% have
also been found for degassed solutions
of the complexes, and a surprisingly
high value of 16% was recorded for iri-
dium(III)bis[2-(5’-benzylsulfonyl-3’,6’-
difluoro)phenylpyridinato-N,C2’](2,4-
decanedionate) in air-equilibrated di-
chloromethane. A unusual stereochem-
istry of the benzylsulfonyl-substituted
dimer and heteroleptic complexes has
1
been detected by H NMR spectrosco-
py, and is characterised by the mutual
cis disposition of the pyridyl nitrogen
atoms of the phenylpyridine ligands,
which differs from the most common
trans arrangement reported in the liter-
ature.
Keywords: fluorine
·
iridium
·
·
luminescence phenylpyridines
·
of iridiumACHTUNGTRENNUNG(III)bis[2-(4’-benzylsulfonyl)-
phenylpyridinato-N,C2’][3-(pentafluoro-
phenyl)-pyridin-2-yl-1,2,4-triazolate] to
stereochemistry · sulfonyl deriva-
tives
Introduction
Recently, cyclometalated iridiumACTHNUTRGNEUNG(III) complexes have
[a] R. Ragni, F. Babudri, A. Pedone, F. Naso, Prof. Dr. G. M. Farinola
Dipartimento di Chimica
emerged as a very interesting class of compounds for various
applications. They can be used as biological labelling re-
agents,[1] photoreductants,[2] singlet oxygen sensitisers[3] and
metal-cation sensing phosphorescent agents,[4] and they rep-
resent, up to now, the most promising phosphorescent dop-
ants for organic light-emitting diodes (OLEDs)[5] because of
their relatively short excited-state lifetime, high photolumi-
nescence efficiency and excellent colour tunability. The tun-
ability of the emission colour is particularly interesting for
applications in photonics and optoelectronics, such as flat-
panel displays and lighting sources. In this context, hetero-
Universitꢀ degli Studi di Bari
via Orabona 4, 70126 Bari (Italy)
Fax : (+39)0805442076
E-mail: farinola@chimica.uniba.it
[b] E. Orselli, G. S. Kottas, Prof. Dr. L. De Cola
Physikalisches Institut
Westfꢁlische Wilhelms-Universitꢁt Mꢂnster
Mendelstrasse 7, 48149 Mꢂnster (Germany)
Fax : (+49)2519802834
E-mail: decola@uni-muenster.de
[c] E. Orselli, G. S. Kottas, Prof. Dr. L. De Cola
Center for Nanotechnology (CeNTech)
leptic iridium complexes [IrACHTNUTRGNENG(U C^N)2(LX)] are very promising
phosphors because, in addition to their easy synthetic acces-
sibility compared with the corresponding homoleptic [Ir-
Heisenbergstrasse 11, 48149 Mꢂnster (Germany)
[d] O. H. Omar, F. Babudri, F. Naso
CNR-ICCOM, Dipartimento di Chimica
Universitꢀ degli Studi di Bari
AHCTUNGRTEG(NNUN C^N)3] materials, they allow fine-tuning of the emission
via Orabona 4, 70126 Bari (Italy)
colour by appropriate design of the chemical structure[6] of
136
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Chem. Eur. J. 2009, 15, 136 – 148

FULL PAPER
the cyclometalating ligands C^N, the most common being 2-
phenylpyridine (ppy), or by systematic control of the
nature[7] and position[8] of substituents on these ligands. The
N,C2’](2,4-decanedionate) 1, Scheme 1) to orange (lmax
558 nm for iridium(III)bis[2-(3’-benzylsulfonyl)phenylpyridi-
nato-N,C2’](2,4-decanedionate) 2, Scheme 1).
=
AHCTUNGTRENNUNG
emission energies of [IrACTHNUTRGNE(NUG C^N)2(LX)] complexes are mainly
determined by both C^N ligand- and metal-based orbitals,
whereas the nature of the ancillary LX ligand plays, with
few exceptions,[9] a secondary role in tuning the photophysi-
cal properties.
In the case of heteroleptic complexes that contain the 2-
phenylpyridine ligand, [Ir(LX)ACHTNUGTRENUNG(ppy)2], the highest occupied
molecular orbital (HOMO) mainly comprises the iridium d
orbitals and the phenyl p orbitals on the 2-phenylpyridines,
and the lowest unoccupied molecular orbital (LUMO) is
mainly comprised of the p* orbitals on the pyridyl rings.[6e]
Therefore, the functionalisation of phenylpyridine ligands
with electron-donating or -withdrawing groups results in sig-
nificant changes in the HOMO–LUMO energy gap and, as
a consequence, fine-tuning of the emission energy of iridium
complexes in the visible spectral region. In particular, much
effort has been devoted to the design and synthesis of blue-
emitting iridium phosphors that also have high emission
quantum yields and good stability for applications in phos-
phorescent organic light-emitting devices (PHOLEDs).[10]
Moreover, the synthesis of efficient “deep blue” emitters
represents a very important step towards the creation of
white-light-emitting diodes (WOLEDs).[11]
The introduction of electron-withdrawing substituents to
the phenyl rings of ppy ligands represents a convenient
structural modification that leads to [Ir(LX)ACTHNUGTRENUNG(ppy)2] com-
plexes with blueshifted emissions (increased HOMO–
LUMO energy gap) by decreasing the HOMO energy while
keeping the LUMO level relatively unchanged. The elec-
tron-withdrawing groups used so far have been fluorine
atoms[7,10] and, in few cases, trifluoromethyl[7f–h] or penta-
fluorophenyl,[8c] acetyl or cyano[12] groups, whereas the effect
of alternative substituents, such as sulfonyl groups, still re-
mains almost completely unexplored.[13]
Herein, we report the synthesis, photophysical and elec-
trochemical characterisation of a new series of heteroleptic
Scheme 1. Schematic formulas and numbering of the synthesised iridium
complexes.
[IrACHTUNGTRENNUNG(C^N)2(LX)] complexes with an electron-withdrawing
benzylsulfonyl group on the C^N ligands and 2,4-decandio-
nate as the third ancillary ligand LX, which was introduced
in place of the more common acetylacetonate to improve
the solubility of these compounds. In particular, we have de-
veloped a straightforward and general synthetic protocol for
the preparation of 2-phenylpyridines with a benzylsulfonyl
group in different positions on the phenyl rings. This meth-
odology has also been extended to the simultaneous func-
tionalisation of the ligands with sulfonyl and fluorine sub-
stituents, to evaluate the combined effect of these electron-
withdrawing groups on the photophysical properties of the
resulting iridium complexes. We found that the emission
energy of these compounds strongly depends on both the
position of sulfonyl groups and the number of fluorine
atoms in the ligands, and this resulted in a wide tuning of
photoluminescence from blue-green (lem =498 nm for
To the best of our knowledge, such a wide shift in the
emission energy that is solely due to the position of the elec-
tron-withdrawing benzylsulfonyl substituent on the cyclome-
talating ligand has never been observed before. The func-
tionalisation of phenylpyridines with other substituents, such
as fluorine atoms,[8a] pentafluorophenyl rings[8c] or methyl
groups[8d] in different positions in the cyclometalating li-
gands, has been reported to tune photoluminescence wave-
length, but only to a lesser extent. Moreover, we have
shown that by replacing the 2,4-decandionate ancillary
ligand with the 2-[5-(perfluorophenyl)-2H-1,2,4-triazol-3-yl]-
pyridine ligand,[10a] a further blueshift in the emission energy
can be attained.
iridiumACHTUNGTRENNUNG(III)bis[2-(4’-benzylsulfonyl)phenylpyridinato-
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137

G. M. Farinola, L. De Cola et al.
Results and Discussion
Synthesis of ligands and complexes: Cyclometalating ligands
18–22 (Table 1) were synthesised by using the general proce-
dure shown in Scheme 2. Following a synthetic route for
Table 1. Cyclometalating ligands 18–22 with the corresponding benzylphenyl
sulfones (12–16) and sulfonyl chlorides (7–11).
7–11
12–16
18–22
A
ACHTUNGTRENNUNG
(63)
(70)
Scheme 2. General procedure for the synthesis of ligands 18–22; dba=di-
benzylideneacetone, TBAB=tetra-N-butyl ammonium bromide.
Substituted 2-phenylpyridines 18–22 were used in the syn-
thesis of the novel heteroleptic iridium complexes 1–5 with
the 2,4-decandione anion as the third ancillary ligand
(Scheme 1). Complexes 1–5 were prepared by a two-step
synthetic protocol that involved the preliminary synthesis of
the corresponding dichloro-bridged dimer complexes 23–27,
and subsequent reaction of these intermediates with the
anionic diketonate ligand derived from the deprotonation of
2,4-decandione 28 by sodium carbonate in ethoxyethanol
(Scheme 3).
(76)
(74)
(40)
(71)
2,4-Decandione 28 was prepared by Claisen-type conden-
sation of 2-octanone with ethyl acetate in the presence of
sodium (Scheme 4) and it was selected as the ancillary
ligand in place of the commonly used acetylacetone[6a] to im-
prove the solubility of the resulting complexes. The synthesis
of isomeric complexes 1, 2 and 3, characterised by the same
b-diketonate ancillary ligand, allows the study of the effect
of the position of the electron-withdrawing benzylsulfonyl
substituent on the phenylpyridine ligands on the photophysi-
cal properties.
(82)
(73)
(70)
(78)
Furthermore, the synthesis of complexes 4 and 5, enabled
the photophysical investigation of the combined effects of
the functionalisation of phenylpyridine ligands with two
electron-withdrawing moieties, that is, benzylsulfonyl groups
and fluorine atoms. In these complexes the b-diketonate an-
cillary ligand and the position of the benzylsulfonyl moiety
were kept unchanged.
In the case of complex 6 (Scheme 1), 2-[5-(perfluoro-
phenyl)-2H-1,2,4-triazol-3-yl]pyridine was used as the third
ancillary ligand, which was synthesised according to the lit-
erature procedure.[10a] The reaction of 2-[5-(perfluoro-
phenyl)-2H-1,2,4-triazol-3-yl]pyridine with iridium dimer
complex 23 was performed under mild conditions and led to
heteroleptic complex 6 in 60% yield (Scheme 5).
chloromethylsulfones reported in the literature,[14] function-
alised phenylbenzylsulfones 12–16 were prepared by using a
one-pot procedure that involved the reaction of a series of
commercially available sulfonyl chlorides 7–11 (Table 1)
with sodium sulfite and sodium hydrogen carbonate in
water at 1008C for three hours. This was followed by nucle-
ophilic substitution of the resulting sulfinate intermediate
salts with benzylbromide in the presence of tetra-N-butyl
ammonium bromide as the phase-transfer catalyst. Finally,
cyclometalating ligands 18–22 were synthesised in good
yields by a Stille cross-coupling reaction of the isolated bro-
mophenyl benzyl sulfones 12–16 with tributyl(pyridin-2-yl)-
stannane 17 in toluene with [Pd
(AsPh3)4] as the catalyst,
The synthesis of 6 allowed us to study the effect of the
change of the ancillary ligand on the photophysical proper-
generated in situ.[15]
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Chem. Eur. J. 2009, 15, 136 – 148

IridiumACHTUNGTRENNUNG(III) Complexes with Sulfonyl and Fluorine Substituents
FULL PAPER
1H NMR spectroscopic characterisation of iridium dimer
complexes 23–27: Information on the stereochemistry of iri-
dium dimer complexes 23–27 can be derived from the inter-
1
pretation of their H NMR spectra and from the comparison
of these spectra with those recorded for the corresponding
ligands 18–22. Figure 1 shows the comparison between
ligand 20 and the corresponding dimer complex 25.
1
The H NMR spectrum of 25 shows two distinct sets of
resonances that correspond to two non-equivalent pairs of
cyclometalated ligands present in the complex. This observa-
1
tion is quite unusual because the H NMR spectra of all iri-
dium dichloro-bridged dimer complexes reported in the lit-
erature[6a,b,16] show only one set of protonic resonances, due
to the equivalence of the four ligands in their structure.
The presence of two sets of protonic signals here observed
can be explained by assuming that the two cyclometalated
ligands bound to each iridium ion are in a mutually cis dis-
position with respect to the nitrogen atoms, contrary to the
trans
arrangement
reported
in
the
literature
(Scheme 6a).[6a,b,16] Furthermore, the 1H NMR spectrum of
25 (Figure 1b) reveals that the two benzyl protons belonging
to each non-equivalent ligand are diastereotopic because
they have two distinct AB signals in the spectral range d=
4.14–4.46 ppm.
This observation implies that dimer complex 25 is chiral
and that it has been obtained as a racemic mixture of two
enantiomers, which thus excludes any achiral cis arrange-
ment and is in accordance with the two alternative chiral cis
structures shown in Scheme 6b and c, and described in
detail in Scheme 7.
Scheme 3. General procedure for the synthesis of the iridium complexes
1–5.
1
As confirmed by the H NMR spectra of 23–27 in the Ex-
perimental Section, the conclusion drawn from the spectro-
scopic analysis of 25 can be extended to the other iridium
dimer complexes reported herein.
Scheme 4. Synthetic route to 2,4-decandione (28).
In agreement with their NMR spectra, the mutual cis dis-
position of the two phenylpyridine ligands is maintained in
heteroleptic complexes 1–6 (Scheme 1).
Absorption and emission spectroscopy: Figure 2 shows
the absorption spectra of all the complexes measured at
ties aiming to a further blue shift in photoluminescence and
to more efficient emission colour tuning.
Scheme 5. Synthetic route for complex 6.
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139

G. M. Farinola, L. De Cola et al.
glet and triplet metal-to-ligand
charge
(1,3MLCT). All complexes with
benzylsulfonyl substituents
transfer
transitions
show similar features, with
maxima at around l=250 and
280 nm and a shoulder at lower
energy. Small shifts in the spec-
tral shape can be attributed to
the substitution pattern on the
phenylpyridine. The absorption
spectrum of complex 6 is simi-
lar to those previously reported
for iridium complexes with tri-
AHCTUNGTRENNUNG
ised emission spectra of com-
plexes 1–6, and all emission
data are summarised in Table 2.
All complexes are highly lumi-
nescent at room temperature in
dichloromethane solutions, and
their emission intensities are
strongly affected by the pres-
ence of oxygen, which is known
to be responsible for triplet-ex-
cited-state emission quench-
ing.[18] The emission maxima
cover a wide window of the
visible spectrum between l=
468 and 560 nm, and the emis-
sion colours vary from blue to
green and orange.
In addition, complexes that
emit at lower energies, such as
2 and 3, show broader and less
structured bands if compared
with, for example, 1 and 6,
which show more structured
bands. According to previously
reported work,[6a,19] 3LC states
normally give emission spectra
with
vibronic
progressions,
whereas 3MLCT states give
broader, featureless bands. In
our case, the emission spectra
measured at 298 K indicate that
for complexes emitting at low
Figure 1. a) 1H NMR spectrum of cyclometalating ligand 20 in [D6]DMSO; b) 1H NMR spectrum of dichloro-
bridged dimer 25 in [D6]DMSO.
room temperature in dichloromethane solutions. All com-
plexes display intense absorption bands in the UV (e=
20000–50000 mÀ1 cmÀ1) and weaker absorption structures in
the visible region (e=700–6000 mÀ1 cmÀ1), similar to those
reported for other iridium complexes.[17,18]
The strong absorption bands in the UV region between
l=240 and 340 nm are attributed to p–p* ligand-centred
(LC) transitions. The weaker transitions observed at lower
energies between l=340 and 530 nm can be ascribed to sin-
energy, the emitting triplet excited state has a substantial
3MLCT character, whereas on going to “bluer” emitting
3
complexes, the contribution from the MLCT state is dimin-
ished, as confirmed by the vibronic structures of 3 and 6.
The substitution of the phenylpyridine moiety with sulfonyl
groups in different positions noticeably affects the emission
colours.
For isomers 1–3, a remarkable shift that depends on the
substitution position of the sulfonyl group on the ppy ligand
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IridiumACHTUNGTRENNUNG(III) Complexes with Sulfonyl and Fluorine Substituents
FULL PAPER
Scheme 6. Schematic representation of the stereochemistry of the di-
chloro-bridged iridium dimer complexes: a) trans arrangement reported
in the literature;[6a,b,16] b and c) cis chiral arrangements.
is noted, with a trend that can be summarised as follows: If
the benzylsulfonyl substituent is ortho to the pyridine ring,
the complex shows the lowest energy emission (l=558 nm)
of the whole series, which is also lower than that of [Ir-
ACHTUNGTRENNUNG(acac)ACHTUNGTRENNUNG
(ppy)2] (lmax =516 nm);[6b] if the sulfonyl moiety is
para to the pyridine ring, a blueshift to l=546 nm is ob-
served; and finally, if the benzylsulfonyl group is meta to the
pyridine (para to the iridium), the bluest emission is ob-
served at l=498 nm. Clearly, the sulfonyl unit has a destabi-
lizing effect on the HOMO when it is meta to the iridium
ion (causing a redshift), whereas a stabilizing effect is ob-
served when the sulfonyl moiety is para to the iridium ion
(blueshift). This was previously observed in similar systems
with electron-withdrawing pentafluorophenyl (F5Ph-) substi-
tuents.[8c]
This trend can be rationalised by taking into account the
charge delocalisation on the SO2-substituted phenyl ring. As
reported earlier for similar compounds,[13b,d] the electron-
withdrawing character of SO2 manifests itself by reducing
the electron density on the iridium centre, which induces a
partial positive charge in the phenyl ring. For complexes 2
and 3, the formal positive charge is mainly localised at the
ortho and para positions with respect to the iridium core,
and never resides on the carbon covalently bound to the iri-
dium atom, whereas for 1 the charge mainly resides on the
carbon directly bound to the iridium and on the meta posi-
tion. This likely lowers the energy of the HOMO, and thus
enhances the HOMO–LUMO gap and shifts the emission
towards the blue region. This is supported by the oxidation
potential measured for these complexes (see Table 2), as dis-
cussed later. It is worth noting that the emission maximum
of 2 is blueshifted by 12 nm with respect to 3, although for
both these complexes the sulfonyl group is in the meta posi-
tion; this difference can be attributed to a steric effect of
the pyridine ring in the ppy ligand.
Scheme 7. Alternative cis chiral arrangements of the dichloro-bridged
dimer 25.
zylsulfonyl group meta to the iridium, so the emission maxi-
mum of complex 5 (lmax =515 nm) is identical to that of [Ir-
A
(ppy)2] (lmax =516 nm).[6b]
ACHTUNGTRENNUNG
shifted by substituting the 2,4-decandionate ancillary ligand
by a 2-[5-(perfluorophenyl)-2H-1,2,4-triazol-3-yl]pyridine to
give complex 6. This ligand was previously reported for
other blue-emitting iridium complexes that displayed intense
blue emission.[10a] In particular, 6 shows a 30 nm hypsochro-
mic shift with respect to analogue 1. This increase in emis-
sion energy on going from 2,4-decandionate to a triazole
Addition of one (4) or two (5) fluorine atoms to the sulfo-
nyl-substituted ppy ligands leads to a further blueshift com-
pared with non-fluorinated analogue 3. However, in compar-
ison with the parent [IrACHTNUTRGENNG(U acac)CAHTUNGTERN(NUGN ppy)2], the hypsochromic shift
induced by the electron-withdrawing fluorine atoms is ne-
gated by the bathochromic shift imposed by having the ben-
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141

G. M. Farinola, L. De Cola et al.
Table 2. Emission spectral data and redox potentials for complexes 1–6.[a]
De-aerated
F[c]
t [ms]
Aerated
[b]
[b,d]
[e]
F[c]
t [ms]
kr [105 sÀ1
]
knr [105 sÀ1
]
lmax
[nm]
t[d] [ms]
E = ACTHNGUTERNNUG
(Red)[e,d] [V]
2
E = (Ox) [V]
1
1
lmax [nm]
2
1
2
3
4
5
6
498
558
546
533
515
468
0.68
0.47
0.71
0.62
0.65
0.55
1.5
2.3
2.7
2.7
3.0
2.0
0.05
0.07
0.08
0.09
0.16
0.08
0.11
0.29
0.26
0.37
0.56
0.28
4.53
2.04
2.62
2.29
2.16
2.75
2.13
2.30
1.07
1.40
1.16
2.25
484
535
533
523
502
460
4.8
8.7
7.6
7.2
6.9
3.6
À1.50[f]
À1.41[f]
À1.33[f]
À1.26[f]
À1.42[f]
À2.33[f]
0.76
0.69
0.67
0.77
0.98
1.04
[a] All data for complexes in CH2Cl2. [b] lex =350 nm. [c] Quantum yields (F) are measured versus quinine bisulfate in 1n H2SO4 (F=0.546). [d] Re-
corded at 77 K in a butyronitrile matrix. [e] Recorded in nitrogen-equilibrated acetonitrile at RT. All data are displayed versus Fc/Fc+. Scan rate:
100 mVsÀ1. [f] Irreversible.
tron-donating effect induced by the ancillary ligand usually
destabilises the 1MLCT state and results in less 1MLCT
character mixed into the lowest-energy excited triplet state
and leading to higher emission energies. This statement is in
agreement with the fact that, as mentioned above, the emis-
sion spectra of 6 indicates an admixture of MLCT and LC
states, with the latter being predominant.
All complexes also exhibit very high quantum yield values
(F) between 40 and 70% in de-aerated conditions (Table 2).
Interestingly, emission quantum yields measured for air-
equilibrated solutions also show remarkably high values
along the series. All complexes display values that are in
general higher than those reported in the literature, which
are typically below 5%.[18] Complex 5 has a quantum yield
Figure 2. Absorption spectra of complexes 1–6 recorded in CH2Cl2 at RT.
The inset shows a magnified view of the spectra between l=350 and
of 16% in aerated conditions, a value almost three times
higher than expected, and, to the best of our knowledge, the
!
~
!
&
^
*
550 nm. : 1, : 2, : 3, : 4, : 5, : 6.
highest reported in the literature for iridium complexes in
the presence of oxygen. We believe that this unexpected be-
haviour could be related to a combination of several factors
that more efficiently prevent oxygen quenching, such as
steric hindrance around the iridium core, the presence of
two F atoms known to have hydrophobic character,[10c] an
electronic effect due to the simultaneous presence of two F
atoms and a sulfonyl group, the position of the substituents
on the ppy ligand or, more important, the lack of a thermal-
ly activated state responsible for the quenching of the emis-
sion at room temperature.
The excited-state lifetimes measured in de-aerated sam-
ples are in the microsecond range between 1.5 and 3 ms, and
they are shortened in the presence of oxygen. However, we
also observed abnormally long lifetimes for several of the
complexes in the aerated solution. For example, complex 5
has an excited-state lifetime of 0.56 ms in air-equilibrated
solutions, which is extraordinarily long for iridium emitters
in the presence of dioxygen.
When frozen at 77 K in a butyronitrile glass matrix, the
emission spectra of complexes 1–6 exhibit a typical rigido-
chromic shift toward higher energies (see Table 2 and
Figure 3. Normalised RT emission spectra of complexes 1–6 recorded in
!
~
!
&
^
*
CH2Cl2 (lex =350 nm). : 1, : 2, : 3, : 4, : 5, : 6.
3
Figure 4), which further indicates the partial MLCT charac-
3
ter of the excited state together with LC character, as sug-
ligand can be attributed to the higher s-donating capability
of the triazole,[20] which mainly results in increased stability
of the HOMO, pushing it to lower energies and increasing
the HOMO–LUMO gap. As already reported,[9b] this elec-
gested by the structure of both emission spectra at 298 and
77 K (vide supra). The lifetimes for the complexes in the
frozen matrices range between 3.6 and 8.7 ms and emission
maxima span from l=460 (6) to 535 nm (2).
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IridiumACHTUNGTRENNUNG(III) Complexes with Sulfonyl and Fluorine Substituents
FULL PAPER
Conclusion
In summary, we have synthesised and characterised a new
series of heteroleptic iridium complexes with benzylsulfonyl
and fluorine substituents on the phenylpyridine ligands and
2,4-decandionate or perfluorophenylpyridinetriazolate as
the ancillary ligand. We have demonstrated that functionali-
sation with two electron-withdrawing moieties, that is, the
fluorine and benzylsulfonyl groups, leads to the ability to
widely tune the photoluminescence from blue to orange, de-
pending on the position in which these substituents are
bound to the phenylpyridines. A further blueshift in emis-
sion is also induced by the choice of the third ancillary
ligand. Surprisingly, a high emission quantum yield and life-
time have also been found in air-equilibrated solutions for
heteroleptic complex 5, which make it a good candidate for
use in biomedical applications.[21]
Figure 4. Normalised emission spectra of complexes 1–6 measured at
!
~
:
&
^
*
77 K (lex =350 nm) in butyronitrile glass matrix. : 1, : 2, : 3, : 4,
!
5, : 6.
Experimental Section
Electrochemistry: The redox properties of complexes 1–6
were studied by cyclic voltammetry (CV) in acetonitrile sol-
utions at room temperature. All the data were measured rel-
ative to an internal ferrocenium/ferrocene (Fc+/Fc) refer-
ence. The results obtained are collected in Table 2. At a
scan rate of 100 mVsÀ1, all reduction processes are irreversi-
ble and the reported values are thus approximate, whereas
the oxidation processes are all reversible and span a rela-
tively wide potential range (0.67–1.04 V).
As anticipated above, the electron-withdrawing capabili-
ties of the sulfonyl group likely manifest themselves in the
oxidation potential values; in particular, looking at isomers
1, 2 and 3, the former exhibits an oxidation potential that is
70 and 90 mV higher than those of 2 and 3, respectively.
This is in agreement with the emission spectral shifts seen
for these complexes, which were examined by considering
the charge delocalisation on the SO2-substituted phenyl
(vide supra). Considering the chemical structure of 3 as the
basic unit for 4 and 5 can be useful for understanding the
electrochemical and photophysical data measured for such
complexes. For 3, the oxidation potential is 0.67 V, whereas
for 4 and 5 it is 0.77 and 0.98 V, respectively, which implies
that addition of one and two fluorine atoms onto the ppy
phenyl ring further lowers the energy of the HOMO level of
the iridium complex.
Spectroscopy: Absorption spectra were measured by using a Varian
Cary 5000 double-beam UV/Vis/NIR spectrometer and baseline correct-
ed. Steady-state emission spectra were recorded by using a HORIBA
Jobin–Yvon IBH FL-322 Fluorolog 3 spectrometer equipped with
a
450 W xenon arc lamp, double grating excitation and emission monochro-
mators (2.1 nmmmÀ1 dispersion; 1200 groovesmmÀ1) and a Hamama-
AHCTUNGERTGtNNUN su R928 photomultiplier tube or a TBX-4-X single-photon-counting de-
tector. Emission and excitation spectra were corrected for source intensi-
ty (lamp and grating) and emission spectral response (detector and gra-
ting) by standard correction curves. Time-resolved measurements were
performed by using the time-correlated single-photon counting (TCSPC)
option on the Fluorolog 3. NanoLEDs (l=295, 402 or 431 nm; full width
at half maximum <750 ps) with repetition rates between 10 kHz and
1 MHz were used to excite the sample. The excitation sources were
mounted directly in the sample chamber at 908 to a double grating emis-
sion monochromator (2.1 nmmmÀ1 dispersion; 1200 groovesmmÀ1) and
collected by a TBX-4-X single-photon-counting detector. The photons
collected at the detector are correlated by a time-to-amplitude converter
to the excitation pulse. Signals were collected by using an IBH DataSta-
tion Hub photon-counting module and data analysis was performed by
using the commercially available DAS6 software (HORIBA, Jobin Yvon
IBH). The goodness of fit was assessed by minimizing the reduced chi-
squared function (c2) and visual inspection of the weighted residuals. The
error on the excited-state lifetimes is estimated to be <8%. Emission
quantum yields were measured by using the method of Demas and
Crosby[22] with quinine bisulfate in 1.0n sulfuric acid as the standard
(F=0.546). The error on the calculated emission quantum yields is about
15%. All solvents were spectrometric grade and all solutions were fil-
tered through a 0.2 mmL syringe filter before measurement. De-aerated
samples were prepared by the freeze-pump-thaw technique. Low-temper-
ature (77 K) emission spectra for glasses and solid-state samples were re-
corded in 5 mm diameter quartz tubes that were placed in a liquid nitro-
gen Dewar with quartz walls.
Finally, as expected, by replacing 2,4-decanedionate (28)
with
2-[5-(perfluorophenyl)-2H-1,2,4-triazol-3-yl]pyridine,
and thus increasing the ancillary ligand field strength, the
oxidation potential on going from 1 to 6 is enhanced by
about 300 mV. This once more clearly indicates that the an-
cillary triazole ligand has the effect of lowering the HOMO
energy, which results in a more blue-emitting complex
(Figure 3).
CV studies: CV was performed by using a Voltalab 40 system from Ra-
diometer Analytical, which consists of a PGZ301 potentiostat and Volta-
master 4 software.[26] The working and counter electrodes were a Pt-disc
and a Pt wire, respectively, and Ag wire was used as a pseudoreference
electrode. All glassware was dried prior to use. The dry electrolyte tetra-
butyl ammonium hexafluorophosphate (>99.0% purity), the analyte and
ferrocene (FeCp2; used as the reference) were dried and degassed at high
temperature and at reduced pressure in a Schlenk flask to eliminate any
moisture and oxygen. The flask was then evacuated and filled three times
with N2. Acetonitrile, freshly distilled from P2O5, was added directly to
Chem. Eur. J. 2009, 15, 136 – 148
ꢃ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
143

G. M. Farinola, L. De Cola et al.
the sealed Schlenk flask by syringe, the solution was sonicated if necessa-
ry and then degassed for ten minutes with a gentle stream of nitrogen.
The degassed solution was injected into the electrochemical cell and,
after the introduction of electrodes, measurements were performed
under a nitrogen atmosphere.
ꢀ8 Hz, 2H); 13C NMR (100 MHz, CDCl3, 258C): d=62.84, 127.76,
128.68, 128.92, 129.08, 130.15, 130.75, 132.14, 136.72 ppm; FTIR (KBr):
n˜ =1390, 1313, 1272, 1149, 1085, 1068, 1012, 829, 774, 751, 697, 637, 549,
525 cmÀ1; elemental analysis calcd (%) for C13H11BrO2S: C 50.17, H 3.56,
S 10.30; found: C 49.90, H 3.76, S 10.21.
Synthesis of ligands and complexes: IrCl3·3H2O was purchased from
Alpha Aesar. Arylsulfonyl chlorides 7–11 and all reagents used in the
syntheses of ligands and complexes were purchased from Aldrich. Tribu-
tyl(pyridin-2-yl)stannane[23] 17 and 2-(5-(perfluorophenyl)-2H-1,2,4-tri-
2-Fluoro-4-(phenylmethanesulfonyl)bromobenzene (15): Yield 82%; m.p.
161–1628C (crystallised from CH3OH); 1H NMR (500 MHz, CDCl3,
258C): d=4.26 (s, 2H), 7.04 (app. d, Jꢀ8.0 Hz, 2H), 7.16–7.33 (m, 5H),
4
7.58 ppm (dd, J=8.3, J
G
ACHTUNGTRENNUNG
azol-3-yl)pyridine[10a] were synthesised according to the literature proce-
2
2
258C): d=62.84, 116.22 (d, J
125.35 (d, 3J
(C,F)=3.8 Hz), 127.52, 128.83, 129.17, 130.77, 134.28, 138.87
(d, 3J(C,F)=5.5 Hz), 158.74 ppm (d, 1J(C,F)=253.5 Hz); 19F NMR
dures and 17 was also purified by distillation in a Bꢂchi GKR-51 appara-
tus (10À3 mbar, 1158C). Toluene, used as the solvent for the Stille cross-
coupling reactions, was freshly distilled from sodium and benzophenone
under a nitrogen atmosphere immediately prior to use. As noted in the
literature,[6,24,25] all reactions involving IrCl3·3H2O were carried out under
a nitrogen atmosphere and with previously degassed solvents. Column
chromatography was performed by using silica gel 60, (40–63 mm) from
Merck, and Merck silica gel 60 F254 aluminium sheets were used for ana-
lytical TLC. FTIR spectra were measured by using a Perkin–Elmer Spec-
trum BX spectrophotometer with dry KBr pellets. 1H, 13C and 19F NMR
spectra were recorded at 400, 100 and 376 MHz, respectively, by using a
Varian Inova 400 spectrometer. 1H and 13C NMR were also recorded at
500 and 125 MHz, respectively, by using a Bruker AM 500 spectrometer.
The residual proton signals of CDCl3, CD2Cl2 and [D6]DMSO at d=7.26,
5.36 and 2.50 ppm, respectively, were used as references for the 1H NMR
spectra, and the signals of CDCl3, CD2Cl2 and [D6]DMSO at d=77.0,
53.8 and 39.43 ppm, respectively, were used as references for the
13C NMR spectra. The 19F signal of trichlorofluoromethane was used as
an internal standard at d=0.0 ppm for the 19F NMR spectra. Melting
points (uncorrected) were obtained on a capillary melting point appara-
tus. Elemental analyses were performed by using a Carlo Erba CHNS-O
EA1108-Elemental Analyzer. Electrospray ionisation (ESI) mass spectra
were recorded in methanol by using a Bruker Daltonics (Bremen, Ger-
many) MicroTof with loop injection.
AHCTUNGTRENNUNG
G
(376 MHz, CDCl3, 258C): d=À103.54 ppm (app. t, Jꢀ7.0 Hz, 1F); FTIR
(KBr): n˜ =1471, 1399, 1315, 1284, 1233, 1149, 1039, 899, 775, 729, 700,
636, 592, 512 cmÀ1; elemental analysis calcd (%) for C13H10BrFO2S: C
47.43, H 3.06, S 9.74; found: C 47.17, H 3.19, S 9.92.
2,5-Difluoro-4-(phenylmethanesulfonyl)bromobenzene (16): Yield 70%;
m.p. 118–1208C (crystallised from CH3OH); 1H NMR (400 MHz, CDCl3,
258C): d=4.53 (s, 2H), 7.19–7.21 (m, 2H), 7.27–7.36 (m, 3H), 7.38 (dd,
3J
A
(H,F)=7.1, 4J
E
G
4
(H,F)=5.0 Hz, 1H); 13C NMR (100 MHz, CD2Cl2, 258C): d=62.26 (d, J-
A
A
R
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
(C,F)=3.2 Hz), 155.59 ppm (dd, 1J(C,F)=249.0, 4J
AHCTUNGTREUNNGN ACHTUNGTRENNUNG ACHTUNGTRENNUNG
3.0 Hz); 19F NMR (376 MHz, CDCl3, 258C): d=À114.20 (ddd, 5J
ACHTUNGTRENNUNG
17.0, 3J
(H,F)=8.4, 4J
(H,F)=6.0 Hz, 1F), À110.05–À109.91 ppm (m, 1F);
FTIR (KBr): n˜ =1471, 1381, 1329, 1320, 1190, 1148, 960, 907, 857, 791,
777, 696, 643, 524 cmÀ1; elemental analysis calcd (%) for C13H9BrF2O2S:
C 44.97, H 2.61, S 9.24; found: C 44.79, H 2.61, S 9.34.
General synthesis of functionalised 2-phenylpyridine ligands 18–22: The
catalyst [PdACHTUNTGRENNUG(AsPh3)4] was synthesised in situ by reacting [Pd2ACHTUNGTRENNUNG(dba)3]
(0.082 g, 0.09 mmol) and trisphenylarsine (0.21 g, 0.7 mmol) in dry tolu-
ene (7 mL) at RT under a nitrogen atmosphere. After few minutes, the
aryl halide (12–16; 3.0 mmol) and a solution of tributyl(pyridin-2-yl)stan-
nane 17 (1.18 g, 3.2 mmol) in toluene (13 mL) were added in sequence,
under a nitrogen atmosphere. The resulting reaction mixture was stirred
for 12 h at 1108C. After cooling to RT, the solvent was removed under
reduced pressure. H2O (20 mL) was then added and the crude product
was extracted with ethyl acetate (3ꢄ15 mL). The organic extracts were
combined and dried with anhydrous Na2SO4. After filtration, the solvent
was distilled in vacuo. In the case of reactions leading to the ligands 20,
21 and 22, a further washing with hexane and subsequent filtration of the
crude products allowed the removal of the soluble organotin byproducts.
Finally, the resulting ligands 18–22 were isolated by column chromatogra-
phy over silica gel.
General synthesis of the aryl bromides 12–16: The sulfonyl chloride (7–
11; 8.0 mmol), sodium sulfite heptahydrate (4.0 g, 16.0 mmol) and sodium
bicarbonate (1.3 g, 16.0 mmol) were dissolved in water (30 mL) under a
nitrogen atmosphere and heated at 1008C for three hours. After cooling
the solution to RT, benzylbromide (8.3 mL, 70 mmol) and the phase-
transfer catalyst tetra-N-butyl ammonium bromide (0.23 g, 0.7 mmol)
were added under a nitrogen flow. The reaction mixture was stirred over-
night at 708C. After cooling to RT, the solid product (12–16) slowly pre-
cipitated from solution. It was isolated by filtration and directly purified
on a Bꢂchner funnel by washing with water (5ꢄ10 mL) and hexane (5ꢄ
10 mL). The product was used in the Stille cross-coupling procedure
without further purification.
3-(Phenylmethanesulfonyl)bromobenzene (12): Yield 63%; m.p. 116–
1178C (crystallised from CH3OH); 1H NMR (400 MHz, CD2Cl2, 258C):
d=4.36 (s, 2H), 7.13–7.19 (m, 2H), 7.32–7.37 (m, 2H), 7.37–7.43 (m,
2H), 7.57–7.62 (m, 1H), 7.78–7.83 ppm (m, 2H); 13C NMR (100 MHz,
CD2Cl2, 258C): d=63.06, 123.18, 127.53, 128.18, 128.95, 129.27, 130.87,
131.20, 131.74, 137.11, 140.23 ppm; FTIR (KBr): n˜ =1455, 1406, 1318,
1294, 1152, 768, 694, 673, 623, 520 cmÀ1; elemental analysis calcd (%) for
C13H11BrO2S: C 50.17, H 3.56, S 10.30; found: C 49.83, H 3.73, S 10.15.
2-(3-Phenylmethanesulfonylphenyl)pyridine (18): Yield 70% (eluent: pe-
troleum ether/ethyl acetate 2:8); m.p.: 91–928C (crystallised from
CH3OH); 1H NMR (400 MHz, CD2Cl2, 258C): d=4.41 (s, 2H), 7.17–7.23
(m, 2H), 7.30–7.40 (m, 4H), 7.62 (t, J=8.0 Hz, 1H), 7.70 (brdt, J=7.7,
1.5 Hz, 1H), 7.73 (brdt, J=8.0, 0.9 Hz, 1H), 7.84 (td, J=7.7, 1.8 Hz, 1H),
8.32–8.34 (m, 1H), 8.36 (brdt, J=7.7, 1.5 Hz, 1H), 8.74 ppm (ddd, J=4.8,
1.8, 0.9 Hz, 1H); 13C NMR (100 MHz, CD2Cl2, 258C): d=63.01, 120.80,
123.43, 127.02, 128.62, 128.87, 128.97, 129.07, 129.72, 131.27, 132.20,
137.35, 139.12, 140.68, 150.17, 155.20 ppm; FTIR (KBr): n˜ =1585, 1494,
1458, 1302, 1277, 1146, 1083, 829, 770, 701, 623, 525 cmÀ1; elemental anal-
ysis calcd (%) for C18H15NO2S: C 69.88, H 4.89, N 4.53, S 10.36; found: C
69.99, H 4.92, N 4.65, S 10.16.
2-(Phenylmethanesulfonyl)bromobenzene (13): Yield 76%; m.p. 88–898C
(crystallised from CH3OH); 1H NMR (400 MHz, CD2Cl2, 258C): d=4.71
(s, 2H), 7.24 (app. d, Jꢀ8 Hz, 2H), 7.27–7.37 (m, 3H), 7.40 (td, J=7.6,
1.1 Hz, 1H), 7.49 (td, J=7.6, 1.7 Hz, 1H), 7.81 (dd, J=7.8, 1.7 Hz, 1H),
7.84 ppm (dd, J=7.8, 1.1 Hz, 1H); 13C NMR (100 MHz, CD2Cl2, 258C):
d=60.09, 121.16, 128.05, 128.18, 128.86, 129.12, 131.14, 132.83, 135.14,
135.67, 137.71 ppm; FTIR (KBr): n˜ =1455, 1429, 1317, 1250, 1200, 1155,
1120, 1024, 882, 790, 762, 705, 601, 549, 529 cmÀ1; elemental analysis
calcd (%) for C13H11BrO2S: C 50.17, H 3.56, S 10.30; found: C 49.92, H
3.67, S 10.60.
2-(2-Phenylmethanesulfonylphenyl)pyridine (19): Yield 40% (eluent: pe-
troleum ether/ethyl acetate 7:3); m.p. 169–1718C (crystallised from
CH3OH); 1H NMR (500 MHz, CDCl3 258C): d=4.86 (s, 2H), 7.20–7.31
(m, 5H), 7.33–7.40 (m, 2H), 7.45 (app. t, Jꢀ8 Hz, 2H), 7.61 (app. t, J
ꢀ8 Hz, 1H), 7.68 (app. d, Jꢀ8 Hz, 1H), 7.80 (app. t, Jꢀ8 Hz, 1H), 8.70–
8.72 ppm (m, 1H); 13C NMR (125 MHz, CDCl3): d=63.52, 112.84,
124.34, 128.09, 128.24, 128.32, 128.49, 130.94, 131.30, 131.47, 133.13,
136.56, 136.64, 141.28, 148.12, 158.01 ppm; FTIR (KBr): n˜ =1582, 1462,
1424, 1309, 1250, 1199, 1155, 1117, 881, 794, 768, 751, 703, 600, 549, 538,
4-(Phenylmethanesulfonyl)bromobenzene (14): Yield 74%; m.p. 158–
1598C (crystallised from CH3OH); 1H NMR (400 MHz, CDCl3, 258C):
d=4.23 (s, 2H), 7.01 (app. d, Jꢀ8 Hz, 2H), 7.21 (app. t, Jꢀ8 Hz, 2H),
7.27 (app. t, Jꢀ8 Hz, 1H), 7.38 (app. d, Jꢀ8 Hz, 2H), 7.51 ppm (app. d, J
144
www.chemeurj.org
ꢃ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 136 – 148

IridiumACHTUNGTRENNUNG(III) Complexes with Sulfonyl and Fluorine Substituents
FULL PAPER
524 cmÀ1; elemental analysis calcd (%) for C18H15NO2S: C 69.88, H 4.89,
N 4.53, S 10.36; found: C 69.89, H 5.06, N 4.50, S 10.21.
128.91, 129.97, 130.80, 130.95, 131.73, 132.14, 133.46, 139.06, 140.11,
144.07, 144.64, 150.89, 152.24, 154.60, 159.96, 164.85, 165.26 ppm; FTIR
(KBr): n˜ =1608, 1575, 1478, 1422, 1303, 1148, 1029, 831, 779, 697, 629,
610, 531, 516 cmÀ1; elemental analysis calcd (%) for C72H56Cl2Ir2N4O8S4:
C 51.20, H 3.34, N 3.32, S 7.59; found: C 51.07, H 3.54, N 3.19, S 7.38;
2-(4-Phenylmethanesulfonylphenyl)pyridine (20): Yield 71% (eluent: pe-
troleum ether/ethyl acetate 1:1); m.p. 173–1768C (crystallised from
CH3OH); 1H NMR (500 MHz, [D6]DMSO, 258C): d=4.73 (s, 2H), 7.17–
7.21 (m, 2H), 7.27–7.33 (m, 3H), 7.45 (ddd, J=7.7, 4.7, 1.0 Hz, 1H), 7.81
(app. d, Jꢀ9 Hz, 2H), 7.95 (td, J=7.7, 1.8 Hz, 1H), 8.09 (dt, J=7.7, 1.0,
1H), 8.29 (app. d, Jꢀ9 Hz, 2H), 8.73 ppm (ddd, J=4.7, 1.8, 1.0 Hz, 1H);
13C NMR (100 MHz, CD2Cl2, 258C): d=63.08, 121.36, 123.74, 127.56,
128.64, 128.89, 129.08, 129.29, 131.23, 137.38, 138.49, 144.72, 150.33,
155.36 ppm; FTIR (KBr): n˜ =1585, 1560, 1491, 1464, 1455, 1434, 1406,
1392, 1304, 1284, 1085, 1026, 1013, 862, 825, 770, 730, 695, 635, 627, 561,
537, 521 cmÀ1; elemental analysis calcd (%) for C18H15NO2S: C 69.88, H
4.89, N 4.53, S 10.36; found: C 69.85, H 5.12, N 4.30, S 10.19.
ESI-MS (+ve, MeOH): m/z (%): 867.3 (100) [M+2Na]2+
.
Tetrakis[2-(3’-benzylsulfonyl)phenylpyridinato-N,C2’](m-dichloro)diiridi-
1
um (24): Yield 78%; H NMR (500 MHz, [D6]DMSO, 258C): d=4.70 (d,
J=13.8 Hz, 2H), 4.74 (s, 2H), 4.77 (s, 2H), 4.87 (d, J=13.8 Hz, 2H), 5.82
(d, J=7.7 Hz, 2H), 6.66 (d, J=7.7 Hz, 2H), 6.84 (t, J=7.8 Hz, 2H), 6.99
(t, J=7.8 Hz, 2H), 7.05 (app. d, Jꢀ7 Hz, 4H), 7.12 (app. t, Jꢀ7 Hz, 4H),
7.19–7.35 (m, 12H), 7.46 (d, J=7.6 Hz, 2H), 7.63–7.71 (m, 4H), 7.76
(app. t, Jꢀ7 Hz, 2H), 8.23 (app. t, Jꢀ8 Hz, 2H), 8.31 (app. t, Jꢀ8 Hz,
2H), 9.29 (d, J=8.4 Hz, 2H), 9.33 (d, J=8.4 Hz, 2H), 9.78 (d, J=5.6 Hz,
2H), 9.98 ppm (d, J=5.6, 2H);13C NMR (125 MHz, [D6]DMSO, 258C):
d=59.10, 59.15, 124.48, 125.21, 125.33, 125.73, 126.64, 127.50, 127.72,
128.07, 128.24, 128.31, 128.50, 129.21, 131.16, 131.31, 134.59, 135.85,
136.76, 137.25, 138.47, 139.46, 140.03, 140.22, 150.13, 151.99, 153.02,
155.25, 163.21, 163.69 ppm; FTIR (KBr): n˜ =1602, 1560, 1475, 1420, 1390,
1317, 1297, 1274, 1153, 1138, 1121, 1060, 787, 769, 696, 619, 527 cmÀ1; ele-
mental analysis calcd (%) for C72H56Cl2Ir2N4O8S4: C 51.20, H 3.34, N
3.32, S 7.59; found: C 51.05, H 3.20, N 3.10, S 7.46; ESI-MS (+ve,
MeOH): m/z (%): 867.3 (100) [M+2Na]2+, 1711.3 (30) [M+Na]+.
2-(2-Fluoro-4-phenylmethanesulfonylphenyl)pyridine (21): Yield 73%
(eluent: petroleum ether/ethyl acetate 4:6); m.p. 151–1538C (crystallised
1
from CH3OH); H NMR (500 MHz, CDCl3 258C): d=4.28 (s, 2H), 7.02–
7.09 (m, 2H), 7.16–7.28 (m, 4H), 7.33 (dd, J=10.2, 1.7 Hz, 1H), 7.44 (dd,
J=8.2, 1.7 Hz, 1H), 7.70 (td, J=7.2, 1.7 Hz, 1H) 7.72–7.77 (m, 1H), 8.05
(t, J=7.7 Hz, 1H), 8.66 ppm (ddd, J=4.8, 1.5, 1.0 Hz, 1H); 13C NMR
(125 MHz, CDCl3, 258C): d=62.71, 116.91 (d, 2J
ACHTUNGTRENNUNG
124.46 (d, 4J
128.93, 130.74, 131.82 (d, 3J
136.64, 139.35 (d, 3J
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
(C,F)=3.4 Hz), 124.84 (d, 4J
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
Tetrakis[2-(5’-benzylsulfonyl)phenylpyridinato-N,C2’](m-dichloro)diiridi-
1
G
um (25): Yield 80%; H NMR (500 MHz, [D6]DMSO, 258C): d=4.16 (d,
À114.40 ppm (m, 1F); FTIR (KBr): n˜ =1585, 1458, 1437, 1398, 1306,
1200, 1146, 1120, 784, 699, 624, 530, 509 cmÀ1; elemental analysis calcd
(%) for C18H14FNO2S: C 66.04, H 4.31, N 4.28, S 9.79; found: C 65.85, H
4.66, N 4.28, S 9.59.
J=13.8 Hz, 2H), 4.34 (d, J=13.8 Hz, 2H), 4.40 (d, J=14.0 Hz, 2H), 4.44
(d, J=14.0 Hz, 2H), 5.79 (d, J=1.8 Hz, 2H), 6.38 (d, J=1.8 Hz, 2H),
6.73 (d, J=7.3 Hz, 4H), 6.87 (d, J=7.3 Hz, 4H), 7.01–7.10 (m, 8H), 7.20
(dd, J=8.1, 1.8 Hz, 2H), 7.23–7.29 (m, 6H), 7.60 (app. t, Jꢀ7 Hz, 2H),
7.65 (app. t, Jꢀ7 Hz, 2H), 7.97 (d, J=8.3 Hz, 2H), 8.00 (d, J=8.3 Hz,
2H), 8.13 (app. t, Jꢀ8 Hz, 2H), 8.19 (app. t, Jꢀ8 Hz, 2H), 8.34 (app. d, J
ꢀ8 Hz, 2H), 8.38 (app. d, Jꢀ8 Hz, 2H), 9.45 (app. d, Jꢀ7 Hz, 2H),
9.73 ppm (app. d, Jꢀ7 Hz, 2H); 13C NMR (100 MHz, [D6]DMSO, 258C):
d=60.74, 60.81, 121.26, 121.84, 121.97, 122.27, 124.08, 124.69, 125.06,
125.37, 128.06, 128.15, 128.20, 128.28, 128.53, 129.64, 130.48, 137.02,
137.88, 138.84, 139.82, 145.04, 148.16, 148.86, 151.29, 164.69, 165.05 ppm;
FTIR (KBr): n˜ =1608, 1562, 1476, 1455, 1427, 1374, 1314, 1298, 1269,
1198, 1151, 1125, 1087, 873, 808, 776, 727, 697, 666, 652, 614, 541,
505 cmÀ1; elemental analysis calcd (%) for C72H56Cl2Ir2N4O8S4: C 51.20,
H 3.34, N 3.32, S 7.59; found: C 51.03, H 3.54, N 3.47, S 7.50; ESI-MS
(+ve, MeOH): m/z (%): 867.3 (100) [M+2Na]2+, 1711.1 (20) [M+Na]+.
2-(2,5-difluoro-4-phenylmethanesulfonylphenyl)pyridine (22): Yield 78%
(eluent: petroleum ether/ethyl acetate 7:3); m.p. 136–1378C (crystallised
from CH3OH); 1H NMR (400 MHz, CD2Cl2, 258C): d=4.62 (s, 2H),
7.29–7.45 (m, 6H), 7.49 (dd, J=9.9, 5.5 Hz, 1H), 7.87 (td, J=7.7, 1.8 Hz,
1H), 7.92–7.97 (m, 1H), 8.14 (dd, J=10.6, 5.7 Hz, 1H), 8.80 ppm (ddd,
J=4.8, 1.7, 1.0 Hz, 1H); 13C NMR (125 MHz, CDCl3, 258C): d=61.71 (d,
4J
25.8, 3J
2J(C,F)=18.2, 3J
(dd, 2J(C,F)=13.6, 3J(C,F)=7.8 Hz), 136.82, 149.80 (app. d, 3J
ACHTUNGTRENNUNG ACHTUNGTRENNUNG ACTUHNGTRENNNGU
A
R
ACHTUNGTRNE(NUNG C,F)=
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
ꢀ2.0 Hz), 149.97, 155.26 (dd, 1J
(C,F)=251.2, 4J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
155.41 ppm (dd, 1J(C,F)=251.9, 4J(C,F)=2.3 Hz); 19F NMR (376 MHz,
ACHTUNGTRENNUNG ACHTUNGTRENNUGN
CD2Cl2, 258C): d=À119.42–À119.23 (m, 1F), À115.05 ppm (ddd, J=19.1,
10.5, 5.5 Hz, 1F). FTIR (KBr): n˜ =1484, 1459, 1442, 1394, 1318, 1145, 895,
789, 696, 632, 527 cmÀ1; elemental analysis calcd (%) for C18H13F2NO2S:
C 62.60, H 3.79, N 4.06, S 9.28; found: C 62.83, H 3.97, N 4.01, S 9.57.
Tetrakis[2-(5’-benzylsulfonyl-3’-fluoro)phenylpyridinato-N,C2’](m-di-
AHCTUNGTRENNUNG
chloro)diiridium (26): Yield 90%; 1H NMR (500 MHz, [D6]DMSO,
258C): d=4.33 (d, J=14.0 Hz, 2H), 4.49 (d, J=14.0 Hz, 2H), 4.50 (d, J=
14.0 Hz, 2H), 4.56 (d, J=14.0 Hz, 2H), 5.46 (brs, 2H), 6.12 (brs, 2H),
6.79 (brd, J=7.9 Hz, 4H), 6.89 (brd, J=7.9 Hz, 4H), 7.01–7.12 (m, 8H),
7.18–7.30 (m, 8H), 7.61–7.70 (m, 4H), 8.14–8.25 (m, 4H), 8.33 (brt, J=
8.2 Hz, 4H), 9.5 (brd, J=5.8 Hz, 2H), 9.7 ppm (brd, J=5.8 Hz, 2H);
13C NMR (100 MHz, [D6]DMSO, 258C): d=60.48 (br), 109.88 (d, 2J-
General synthesis of iridium dimer complexes 23–27:[16,25] Dichloro-bridg-
ed dimer complexes 23–27 were synthesised by treating IrCl3·3H2O
(0.35 g, 1.0 mmol) with the ligand (18–22; 2.5 mmol) in a 2-ethoxyetha-
nol/H2O mixture (3:1, 25 mL) at reflux under a nitrogen atmosphere for
12 h. After cooling to RT, water (25 mL) was added to the reaction mix-
ture and the product was filtered in a Bꢂchner funnel and then washed
with hexane (25 mL) and ethanol (5 mL). The product was dissolved in
dichloromethane (100 mL), dried with anhydrous Na2SO4 and isolated by
filtration and distillation of the solvent under reduced pressure. In the
case of dimer complexes 26 and 27, further purification by column chro-
matography over silica gel was carried out. In particular, the residual
ligand was first recovered by using petroleum ether/ethyl acetate (1:1) as
the eluent, then the iridium dimer complex was isolated by eluting with
acetone/petroleum ether (6:4).
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
[D6]DMSO, 258C): d=À107.58 (d, J=11.8 Hz, 2F), À106.19 ppm (d, J=
11.8 Hz, 2F); FTIR (KBr): n˜ =1601, 1583, 1558, 1473, 1391, 1306, 1225,
1146, 1121, 932, 774, 697, 624, 534 cmÀ1; elemental analysis calcd (%) for
C72H52Cl2F4Ir2N4O8S4: C 49.11, H 2.98, N 3.18, S 7.28; found: C 49.07, H
3.21, N 3.23, S 7.53; ESI-MS (+ve, MeOH): m/z (%): 903.3 (100)
[M+2Na]2+, 1783.3 (10) [M+Na]+.
Tetrakis[2-(4’-benzylsulfonyl)phenylpyridinato-N,C2’](m-dichloro)diiridi-
um (23): Yield 74%; 1H NMR (400 MHz, [D6]DMSO, 258C): d=4.48 (s,
4H), 4.49 (d, J=13.8, 2H), 4.55 (d, J=13.8, 2H), 5.78 (d, J=8.2 Hz, 2H),
6.36 (d, J=8.1 Hz, 2H), 6.90–7.25 (m, 24H), 7.57 (app. t, Jꢀ7 Hz, 2H),
7.66 (app. t, Jꢀ7 Hz, 2H), 7.98 (brs, 2H), 8.03 (brs, 2H), 8.09 (app. t, J
ꢀ8 Hz, 2H), 8.16 (app. t, Jꢀ8 Hz, 2H), 8.26 (d, J=8.5 Hz, 2H), 8.30 (d,
J=8.0 Hz, 2H), 9.50 (d, J=6.0 Hz, 2H), 9.75 ppm (d, J=6.0 Hz, 2H);
13C NMR (100 MHz, [D6] DMSO, 258C): d=60.61, 60.64, 120.51, 121.15,
122.60, 123.82, 124.32, 125.04, 127.42, 128.05, 128.11, 128.52, 128.59,
Tetrakis[2-(5’-benzylsulfonyl-3’,6’-difluoro)phenylpyridinato-N,C2’](m-di-
chloro)diiridium (27): Yield 85%; 1H NMR (400 MHz, CD2Cl2, 258C):
d=4.09–4.25 (s, 8H), 6.87–6.97 (m, 12H), 7.02 (dd, J=10.8, 4.5 Hz, 4H),
7.13 (app. t, Jꢀ7.5 Hz, 8H), 7.19–7.25 (m, 4H), 8.02 (app. t, Jꢀ8 Hz,
4H), 8.56 (brd, Jꢀ8 Hz, 4H), 9.13 ppm (brd, J= ꢀ5 Hz, 4H); 13C NMR
Chem. Eur. J. 2009, 15, 136 – 148
ꢃ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
145

G. M. Farinola, L. De Cola et al.
(100 MHz, CD2Cl2, 258C): d=61.81, 113.00, 113.29, 116.01, 119.35,
(400 MHz, CDCl3, 258C): d=14.16, 22.87, 27.76, 28.70, 29.01, 32.00,
42.22, 60.31, 60.39, 100.55, 123.69, 123.74, 125.74, 125.76, 125.82, 125.96,
127.89, 127.96, 128.14, 128.26, 128.73, 128.96, 131.22, 131.26, 136.11,
136.21, 138.44, 138.49, 139.32, 139.55, 142.02, 142.08, 149.35, 149.44,
154.22, 154.34, 165.11, 165.16, 185.71, 189.39 ppm; FTIR (KBr): n˜ =1575,
1561, 1512, 1474, 1404, 1316, 1296, 1271, 1152, 1139, 1121, 785, 768, 696,
619, 527 cmÀ1; elemental analysis calcd (%) for C46H45IrN2O6S2: C 56.48,
H 4.64, N 2.86, S 6.56; found: C 56.46, H 4.45, N 2.88, S 6.58; HRMS:
m/z calcd for C46H45IrN2O6S2: 1001.2240 [M+Na]+; found 1001.2235.
124.61, 125.30, 125.52, 125.78–126.28 (m), 126.32, 126.69, 127.64, 128.90,
129,12, 130.78, 138.86, 141.67 (dd, 2J(C,F)=14.5, 3J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
152.84, 155.44 (d, 1J
(C,F)=256.1 Hz), 160.20 (d, 1J
E
3
164.25 ppm (d, J
N
À116.35, (dd, J=21.1, 10.8 Hz, 2F), À108.60 ppm (dd, J=21.1, 4.5 Hz,
2F); FTIR (KBr): n˜ =1478, 1424, 1371, 1317, 1149, 1120, 827, 792, 698,
542,
533,
497 cmÀ1
;
elemental
analysis
calcd
(%)
for
C72H48Cl2F8Ir2N4O8S4: C 47.18, H 2.64, N 3.06, S 7.00; found: C 46.93, H
2.55, N 3.01, S 6.76; ESI-MS (+ve, MeOH): m/z (%): 939.3 (100)
[M+2Na]2+, 1855.3 (10) [M+Na]+.
IridiumACTHNUTRGNE(NUG III)bis[2-(5’-benzylsulfonyl)phenylpyridinato-N,C2’](2,4-decanedi-
onate) (3): Yield 52%; 1H NMR (400 MHz, CD2Cl2, 258C): d=0.87 (t,
J=7.0 Hz, 3H), 0.97–1.48 (m, 8H), 1.87 (s, 3H), 2.07 (t, J=7.3 Hz, 2H),
4.06–4.22 (m, 4H), 5.33 (s, 1H), 6.40 (d, J=1.7 Hz, 1H), 6.45 (d, J=
1.7 Hz, 1H), 6.89 (app. t, Jꢀ8 Hz, 4H), 7.13 (app. t, Jꢀ8 Hz, 4H), 7.19–
7.40 (m, 6H), 7.69 (d, J=8.1 Hz, 1H), 7.72 (d, J=8.1 Hz, 1H), 7.86–8.10
(m, 4H), 8.43 ppm (app. t, Jꢀ6 Hz, 2H); 13C NMR (100 MHz, CD2Cl2,
258C): d=14.22, 22.89, 27.40, 28.63, 28.92, 31.99, 41.94, 62.73, 100.53,
120.31, 120.48, 121.28, 121.31, 123.87, 123.94, 123.98, 124.04, 128.58,
128.61, 128.75, 130.92, 130.96, 132.05, 132.40, 137.09, 137.22, 138.29,
138.33, 148.19, 148.28, 148.86, 148.98, 150.92, 166.32, 166.37, 185.37,
189.12 ppm; FTIR (KBr): n˜ =1607, 1574, 1512, 1475, 1428, 1403, 1311,
Synthesis of decane-2,4-dione (28): 2-Octanone (8.0 mL, 51.0 mmol) was
dissolved in dry ethyl acetate (130 mL) under a nitrogen atmosphere and,
after cooling to 08C, sodium (2.3 g, 102.0 mmol) was added. The reaction
mixture was stirred at 08C for one hour, then allowed to warm to RT and
stirred overnight. The resulting yellow solution was quenched with ice
and aqueous HCl (1.2m). The crude product was extracted with ethyl
acetate (100 mL), and the organic extract dried with anhydrous Na2SO4,
filtered and distilled under vacuo. The liquid crude product was first puri-
fied by distillation in a Bꢂchi GKR-51 apparatus (11 torr, 115–1208C)
and then by column chromatography over silica gel, eluting with a mix-
ture of petroleum ether and ethyl acetate (95:5) as eluent (yield 95%).
This compound exists as a mixture of keto (15%) and enol (85%) forms,
as determined by the integral values of proton resonance peaks at d=
3.54 (for the keto form) and 5.46 ppm (for the enol form). 1H NMR
(500 MHz, CDCl3/D2O, 25 8C): d=0.80–0.90 (m, 3H), 1.20–1.36 (m, 6H),
1.50–1.62 (m, 2H), 2.02 (s, 3H; enol form), 2.20 (s, 3H; keto form), 2.23
(t, J=7.6 Hz, 2H; enol form), 2.47 (t, J=7.4 Hz, 2H; keto form), 3.54 (s,
2H; keto form), 5.46 ppm (s, 1H; enol form); 13C NMR (400 MHz,
CDCl3, 258C): d=13.87, 22.36, 24.80, 25.54, 28.76, 31.42, 38.10, 43.67
(keto form), 57.68 (keto form), 99.58 (enol form), 191.29 (enol form),
194.14 (enol form), 202.05 (keto form), 204.16 ppm (keto form).
1297, 1149, 774, 696, 540 cmÀ1
C46H45IrN2O6S2: C 56.48, H 4.64, N 2.86, S 6.56; found: C 56.26, H 4.44,
2.85, 6.78; HRMS: m/z calcd for C46H45IrN2O6S2: 1001.2240
[M+Na]+; found 1001.2213.
Iridium(III)bis[2-(5’-benzylsulfonyl-3’-fluoro)phenylpyridinato-N,C2’](2,4-
; elemental analysis calcd (%) for
N
S
AHCTUNGTRENNUNG
decanedionate) (4): Yield 50%; 1H NMR (500 MHz, CD2Cl2, 258C): d=
0.88 (t, J=7.1 Hz, 3H), 0.91–1.46 (m, 8H), 1.87 (s, 3H), 2.07 (t, J=
7.3 Hz, 2H), 4.16 (brs, 2H), 4.17 (brs, 2H), 5.32 (s, 1H), 6.09–6.13 (m,
1H), 6.15–6.18 (m, 1H), 6.93 (t, J=7.0 Hz, 4H), 7.02 (d, J=11.4 Hz,
1H), 7.05 (d, J=11.2 Hz, 1H), 7.13 (t, J=7.0 Hz, 4H), 7.27–7.39 (m,
4H), 7.91–7.99 (m, 2H), 7.36–7.46 ppm (m, 4H); 13C NMR (100 MHz,
CD2Cl2, 258C): d=14.19, 22.87, 27.26, 28.58, 28.86, 31.97, 41.77, 62.73,
General synthesis of acac-type iridium complexes 1–5: The dichloro-
bridged dimer complex (0.1 mmol), decane-2,4-dione 28 (0.042 g,
0.25 mmol) and sodium carbonate (0.12 g, 1.1 mmol) were suspended in
2-ethoxyethanol (6 mL) and stirred for 12 h at 1208C under a nitrogen at-
mosphere. After cooling to RT, the reaction mixture was diluted with di-
chloromethane and water was added. The reaction product was extracted
with dichloromethane (3ꢄ15 mL) and the organic phase was dried with
anhydrous Na2SO4. After the distillation of the solvent at reduced pres-
sure, the heteroleptic iridium complex (1–5) was isolated by column chro-
matography over silica gel with petroleum ether/acetone (7:3) as the
eluent.
100.60, 108.84 (d, 4J
124.08, 124.63 (d, 2J(C,F)=15.2 Hz), 124.82 (d, 2J
(d, 2J(C,F)=31.4 Hz), 128.25 (d, 2J
(C,F)=31.5 Hz), 128.47, 128.57,
128.74, 128.77, 130.90, 130.94, 137.92 (d, 3J(C,F)=7.6 Hz), 138.06 (d, 3J-
(C,F)=7.6 Hz), 138.29 (d, 3J(C,F)=4.5 Hz), 138.34 (d, 3J
(C,F)=4.5 Hz),
138.82, 138.86, 148.87, 148.97, 151.74, 151.79, 159.88 (d, 1J
(C,F)=
260.4 Hz), 159.92 (d, 1J(C,F)=260.7 Hz), 163.96 (d, 3J
(C,F)=7.2 Hz),
164.03 (d, 3J(C,F)=7.3 Hz), 185.56, 189.26 ppm; 19F NMR (376 MHz,
A
ACHTUNGERTN(NUNG C,F)=2.7 Hz), 123.97,
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
CD2Cl2, 258C): d=À112.70 (d, J=11.2 Hz, 1F), À112.48 ppm (d, J=
11.4 Hz, 1F); FTIR (KBr): n˜ =1576, 1513, 1473, 1390, 1307, 1221, 1143,
1121, 930, 791, 773, 696, 626, 533 cmÀ1; elemental analysis calcd (%) for
C46H43F2IrN2O6S2: C 54.48, H 4.27, N 2.76, S 6.32; found: C 54.29, H 4.49,
IridiumACHTUNGTRENNUNG(III)bis[2-(4’-benzylsulfonyl)phenylpyridinato-N,C2’](2,4-decanedi-
onate) (1): yield: 55%; 1H NMR (500 MHz, CDCl3, 258C): d=0.81 (t,
J=7.2 Hz, 3H), 0.86–1.10 (m, 4H), 1.13 (q, J=7.0 Hz, 2H), 1.21–1.35 (m,
2H), 1.82 (s, 3H), 2.01 (t, J=7.3, 2H), 4.15–4.23 (m, 4H), 5.25 (s, 1H),
6.32 (d, J=8.0 Hz, 1H), 6.39 (d, J=8.0 Hz, 1H), 6.70 (t, J=2.1 Hz, 1H),
7.00–7.05 (m, 5H), 7.15 (td, J=7.7, 1.5 Hz, 4H), 7.21–7.32 (m, 4H), 7.59
(d, J=1.9 Hz, 1H), 7.64 (d, J=1.9 Hz, 1H), 7.71–7.86 (m, 4H), 8.43–
8.47 ppm (m, 2H); 13C NMR (125 MHz, CDCl3, 258C): d=14.07, 22.50,
26.85, 28.51, 28.65, 31.63, 41.46, 63.01, 100.35, 119.02, 119.22, 122.69,
122.78, 123.42, 123.54, 127.55, 127.67, 128.34, 128.44, 128.49, 128.59,
130.22, 130.29, 130.93, 133.48, 133.74, 137.83, 137.89, 145.62, 145.70,
148.31, 148.40, 158.72, 158.82, 166.48, 166.56, 185.13, 188.73 ppm; FTIR
(KBr): n˜ =1573, 1512, 1423, 1403, 1305, 1148, 1030, 779, 696, 629, 610,
531 cmÀ1; elemental analysis calcd (%) for C46H45IrN2O6S2: C 56.48, H
4.64, N 2.86, S 6.56; found: C 56.38, H 4.78, N 2.96, S 6.82; HRMS: m/z
calcd for C46H45IrN2O6S2: 1001.2240 [M+Na]+; found 1001.2255.
N
2.81,
[M+Na]+; found 1037.2070.
Iridium(III)bis[2-(5’-benzylsulfonyl-3’,6’-difluoro)phenylpyridinato-
S 6.15; HRMS: m/z calcd for C46H43F2IrN2O6S2: 1037.2052
AHCTUNGTRENNUNG
N,C2’](2,4-decanedionate) (5): Yield 72%; 1H NMR (500 MHz, CD2Cl2,
258C): d=0.87 (t, J=7.2 Hz, 3H), 0.90–1.41 (m, 8H), 1.90 (s, 3H), 2.11
(t, J=7.0 Hz, 2H), 4.28 (s, 4H), 5.42 (s, 1H), 6.93–7.03 (m, 6H), 7.18
(app. t, Jꢀ8 Hz, 4H), 7.23–7.30 (m, 2H), 7.34–7.41 (m, 2H), 7.94–8.02
(m, 2H), 8.44 (app. t, Jꢀ8 Hz, 2H), 8.52 ppm (app. d, Jꢀ6 Hz, 2H);
13C NMR (100 MHz, CD2Cl2): d=14.20, 22.85, 27.21, 28.54, 28.78, 31.96,
41.69, 61.69 (br), 100.91, 111.51, 111.74, 127.67, 123.79, 124.72 (d, 2J-
A
ACHTUNGTRENUN(NG C,F)=20.9 Hz), 125.00–125.50 (m), 127.80,
2
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
IridiumACHTUNGTRENNUNG(III)bis[2-(3’-benzylsulfonyl)phenylpyridinato-N,C2’](2,4-decanedi-
onate) (2): yield: 60%; 1H NMR (400 MHz, CD2Cl2, 258C): d=0.83 (t,
J=7.1 Hz, 3H), 1.00–1.42 (m, 8H), 1.87 (s, 3H), 2.00–2.14 (m, 2H), 4.49
(d, J=13.7 Hz, 2H), 4.56 (d, J=13.7 Hz, 2H), 4.56 (s, 2H), 5.37 (s, 1H),
6.58 (dd, J=7.6, 1.3 Hz, 1H), 6.67 (dd, J=7.6, 1.4 Hz, 1H), 6.74 (t, J=
7.7 Hz, 2H), 7.09 (app. t, Jꢀ7 Hz, 4H), 7.17 (app. t, Jꢀ7.5 Hz, 2H),
7.23–7.30 (m, 2H), 7.35–7.42 (m, 2H), 7.55 (dd, J=5.0, 1.4 Hz, 1H), 7.57
(dd, J=5.0, 1.4 Hz, 1H), 8.01–8.06 (m, 2H), 8.68 (dd, J=5.7, 0.7 Hz,
1H), 8.69 (dd, J=5.7, 0.7 Hz, 1H), 9.63–9.69 ppm (m, 2H); 13C NMR
AHCTUNGTRENNUNG
CD2Cl2, 258C): d=À117.66 (dd, J=22.0, 11.0 Hz, 1F), À117.58 (dd, J=
22.0, 11.0 Hz, 1F), À107.26 (dd, J=22.0, 4.5 Hz, 1F), À106.49 ppm (dd,
J=22.0, 4.7 Hz, 1F); FTIR (KBr): n˜ =1569, 1514, 1423, 1404, 1369, 1319,
1151, 1121, 826, 791, 697, 543, 497 cmÀ1; elemental analysis calcd (%) for
C46H41F4IrN2O6S2: C 52.61, H 3.94, N 2.67, S 6.11; found: C 52.72, H 4.21,
N 2.71, S 6.26; HRMS: m/z calcd for C46H41F4IrN2O6S2: 1073.1864 [M
+Na]+; found 1073.1849.
146
www.chemeurj.org
ꢃ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 136 – 148

IridiumACHTUNGTRENNUNG(III) Complexes with Sulfonyl and Fluorine Substituents
FULL PAPER
Synthesis of iridium
G
Fukuda, T. Wakimoto, S. Miyaguchi, Jpn. J. Appl. Phys. 1999, 38,
L1502 L1504.
[3-(pentafluoro-phenyl)-pyridin-2-yl-1,2,4-triazolate] (6): Dimer complex
23 (0.17 g, 0.1 mmol) and 3-(2,3,4,5,6-pentafluorophenyl)-pyridin-2-yl-
1,2,4-triazole (0.066 mg, 0.21 mmol) were dissolved under a nitrogen at-
mosphere in dichloromethane (6 mL) and ethanol (6 mL). The solution
was stirred for 24 h at 408C under a nitrogen atmosphere. After cooling
to RT, the reaction mixture was diluted with dichloromethane and water
was added. The reaction product was extracted three times with dichloro-
methane (3ꢄ10 mL) and the organic extracts were dried with anhydrous
Na2SO4. Then the solvent was removed by distillation under reduced
pressure and complex 6 was isolated by using column chromatography
over silica gel with a mixture of petroleum ether/acetone (1:1) as the
eluent (60% yield). 1H NMR (500 MHz, CD2Cl2, 258C): d=4.27 (d, J=
13.6 Hz, 1H), 4.28 (d, J=14.0 Hz, 1H), 4.30 (d, J=14.0 Hz, 1H), 4.32 (d,
J=13.6 Hz, 1H), 6.50 (d, J=8.0 Hz, 1H), 6.57 (d, J=8.0 Hz, 1H), 7.07–
7.16 (m, 6H), 7.18 (dd, J=8.05, 1.9, 1H), 7.20–7.34 (m, 8H), 7.67 (ddd
J=5.8, 1.4, 0.7 Hz, 1H), 7.74 (ddd J=5.5, 1.5, 0.9 Hz, 1H), 7.77–7.92 (m,
7H), 7.98 (td, J=7.8, 1.6 Hz, 1H), 8.32 ppm (brd, J=8.0 Hz, 1H);
13C NMR (125 MHz, CD2Cl2, 258C): d=63.13, 63.16, 109.95 (td, J=16.7,
3.8 Hz), 120.25, 120.30, 122.17, 124.11, 124.22, 124.39, 124.68, 125.50,
128.46, 128.67, 128.71, 128.83, 128.92, 128.94, 129.18, 131.22, 131.37,
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1774–1775; b) H.-C. Li, P.-T. Chou, Y.-H. Hu, Y.-M. Cheng, R.-S.
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131.81, 132.38, 132.55, 133.09, 138.06 (dm (doublet of multiplet), 1J
ACHTUNGTRENNUNG
ꢀ251 Hz), 138.33, 138.62, 139.68, 141.05 (dm, 1J
ACHTUNGTRENNUNG
(dm, 1J
(C,F)ꢀ251 Hz), 145.15, 146.03, 149.23, 149.95, 150.32, 151.54,
153.70 (br), 159.40, 163.69, 164.12, 166.31, 166.53 ppm; 19F NMR
(376 MHz, CD2Cl2): d=À163.00 (td, J=21.0, 7.0 Hz, 2F), À155.32 (t, J=
21.0 Hz, 1F), À139.67 ppm (dd, J=21.0, 7.0 Hz, 2F); FTIR (KBr): 1610,
1576, 1536, 1517, 1496, 1477, 1438, 1424, 1305, 1149, 1091, 1030, 990, 841,
779, 754, 697, 629, 610, 531 cmÀ1; elemental analysis calcd (%) for
C49H32F5IrN6O4S2: C 52.54, H 2.88, N 7.50, S 5.73; found: C 52.68, H 3.07,
N
7.45,
S 5.94; HRMS: m/z calcd for C49H32F5IrN6O4S2: 1143.1368
[M+Na]+; found 1143.1474.
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This work was financially supported by the Ministero dell’Istruzione, del-
lꢅUniversitꢀ e della Ricerca (MIUR; Progetto FIRB 2003 SYNERGY
RBNE03S7XZ), by Philips Research (SENTER; TRIPLED RWC-061-
JH-04063-jh) and by the Conferenza dei Rettori delle Universitꢀ Italiane
(CRUI) and Deutscher Akademischer Austauschdienst (DAAD) (Pro-
gramma Vigoni D/05/54254).
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Received: June 25, 2008
Published online: November 19, 2008
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