Synthesis, structures, and unique luminescent properties of tridentate C^C^N cyclometalated complexes of iridium

Article abstract of DOI:10.1002/ejic.201100055

The first C^C^N cyclometalated complexes of iridium that bear tridentate pyridylbiphenylene ligands are reported herein. These complexes were synthesized in good yields by means of the directed C-C bond activation of biphenylene with the assistance of pyr

Full text of DOI:10.1002/ejic.201100055

FULL PAPER
DOI: 10.1002/ejic.201100055
Synthesis, Structures, and Unique Luminescent Properties of Tridentate
∧ ∧
C C N Cyclometalated Complexes of Iridium
Yuji Koga,*[a] Marina Kamo,[a] Yuji Yamada,[a] Taisuke Matsumoto,[b] and
Kouki Matsubara*[a]
Keywords: Synthesis design / Iridium / N ligands / Luminescence / Near-infrared emission
∧
∧
The first C C N cyclometalated complexes of iridium that
bear tridentate pyridylbiphenylene ligands are reported
herein. These complexes were synthesized in good yields by
means of the directed C–C bond activation of biphenylene
with the assistance of pyridyl group precoordination. Their
photoluminescent performances were also studied and show
unique luminescent properties at longer wavelengths in the
near-infrared range than that of previously synthesized
∧
∧
C N C cyclometalated iridium complexes.
alated tridentate ligands allow easy electron transfer be-
tween the conjugated π orbital and the metal d orbital due
to a large overlap, and the rigid structure derived from the
strong tridentate coordination including metal–carbon σ
bonds makes the complex stable[11] and suppresses the radi-
ationless deactivation process.
Introduction
Recently, phosphorescent materials have been widely re-
ported as organic electroluminescent devices,[1,2] sensor ma-
terials,[3] and bioimaging probes.[4] Phosphorescent materi-
als are expected to exhibit higher luminescent efficiency
than fluorescent ones, because both triplet and singlet exci-
tons generate in 3:1 ratios when excited. Iridium,[5] plati-
num,[6] and rhenium compounds[7] are chemically stable
and can emit several colors of light even at room tempera-
ture. Quite recently, luminescence in the near-infrared range
has also been reported.[8] Cyclometalated complexes of irid-
ium that bear conjugated chelate ligands have attracted at-
tention in these studies because these compounds have great
potential to exhibit highly efficient luminescence at room
temperature.[5] Tris(phenylpyridine)iridium, [Ir(ppy)3], in
which ppy is 2-phenylpyridine, and its analogues are well
known as stable and efficient luminescent materials.[5a]
Some examples of these are shown in Figure 1. Williams et
al.[9] have reported that iridium complexes that bear triden-
tate conjugated ligands exhibit higher quantum yields [Φ =
0.76: for [Ir(dpyx)(ppy)Cl], in which dpyx is 1,3-bis(2-pyr-
idyl)-4,6-dimethylbenzene] than that of the bidentate ana-
logue fac-[Ir(ppy)3] (Φ = 0.40). Haga et al. have also shown
the effectiveness of tridentate ligands in other luminescent
organometallic compounds.[10] These high luminescent effi-
ciencies are believed to be derived from two facts: cyclomet-
Figure 1. Structures of bidentate and tridentate complexes of irid-
ium.
∧ ∧
The above findings prompted us to design new C C N-
type tridentate ligands to study the luminescent properties
of iridium complexes. To the best of our knowledge, there
∧ ∧
have been no reported C C N complexes. Previous syn-
thetic approaches using pyridylbiphenyl with iridium chlo-
ride to obtain the iridium complexes have been unsuccess-
ful.[12] Only DFT calculations of a gold complex that bears
such tridentate ligands are reported, and this study com-
pares the orbital relationships and luminescent properties
∧ ∧
∧ ∧
∧ ∧
of C C N with its analogues, C N C, N C N, and
[13]
∧ ∧
N N C.
We describe here a synthetic route to the irid-
∧ ∧
ium C C N cyclometalated complexes using pyridylbi-
[a] Department of Chemistry, Fukuoka University,
8-19-1 Nanakuma, Fukuoka 814-0180, Japan
Fax: +81-92-865-6030
∧ ∧
phenylene as a starting compound to form a C C N cyclo-
metalated moiety, as oxidative addition of the C–C bond of
biphenylene to iridium has been reported previously.[14] As
E-mail: y-koga@fukuoka-u.ac.jp
kmatsuba@fukuoka-u.ac.jp
∧ ∧
a result, we have successfully prepared a series of C C N
[b] Analytical Center, Institute for Materials Chemistry and
Engineering, Kyushu University,
cyclometalated iridium complexes for the first time, deter-
mined these structures, and examined the luminescent prop-
erties.
6-1 Kasuga, Fukuoka 816-8580, Japan
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100055.
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Y. Koga, K. Matsubara et al.
FULL PAPER
The formation of 7 encouraged us to synthesize a new
series of luminescent complexes of iridium by its reaction
with conjugated aromatic compounds. The reaction of 7
with 6-phenyl-2,2Ј-bipyridyl (8) in glycerol at 130–200 °C in
the presence of a base formed a complicated mixture
(Scheme 3). As shown in Table 1, a small amount of the
target product 9 along with byproducts 10–13 were isolated
by chromatography. Unfortunately, the yields of 9 were less
than 5%, and even when the reaction was conducted at
lower temperatures, 160 and 130 °C, the yields did not im-
prove (Table 1, entries 8–10). Under most reaction condi-
Results and Discussion
Syntheses of Pyridylbiphenylene and Iridium Complexes
The synthetic scheme to obtain pyridylbiphenylene (6) is
shown in Scheme 1, in which m-dibromobenzene (1) was
used as the starting material and the target compound 6
was isolated from the reaction of bromobiphenylene (5)
with 2-(tributylstannyl)pyridine by means of Stille coupling
in excellent yield.[9]
∧ ∧
tions, reductive elimination of the C C N ligand occurs to
form iridium complexes 10 and 11 (entry 1) or 3-pyridylbi-
phenyl (13) (entries 2–10) in low to moderate yields, proba-
bly following the oxidative addition of some C–H bonds in
8 to generate a hydride species. Thus, we found that the
bases were not effective for halogen extraction in this reac-
tion. When two equivalents of 8 were used without the base,
only 10 was formed, and the isolated yield was up to 65%
by recrystallization from chloroform/ethyl acetate (entry 2).
Scheme 1. Synthetic route for 6.
The reaction of chloro(1,5-cyclooctadiene)iridium(I) di-
mer [{IrCl(cod)}2] with 6 (2 equiv.) in 1,2-dichloroethane
∧ ∧
under reflux conditions gave the first C C N cyclomet-
∧ ∧
alated complex of iridium, [IrCl(cod)(C C N-pybp)] (7, in
which pybp is pyridylbiphenyl) in 92% yield (Scheme 2). As
1
observed in the H NMR spectra of the crude mixture, no
other complexes were formed through oxidative addition of
the biphenylene C–C bonds in 6, furthest from the pyridine
ring.
Scheme 2. Preparation of 7 from [{IrCl(cod)}2] and 6.
Scheme 3. The reaction of 7 with 8 in the presence of base.
Table 1. The reaction of iridium complex 7 with 6-phenylbipyridyl 8 (1 equiv.).
Entry Solvent
Base
T [°C]
t [h]
Yields [%]
Recovery [%]
9
10
11
12
13
7
8
1
glycerol
glycerol
glycerol
glycerol
glycerol
ethylene glycol
glycerol
glycerol
glycerol
–
–
200
200
200
200
200
195
160
160
130
130
1
1
1
1
1
1
1
24
24
24
0
0
5
2
26(40[a]
69
trace
trace
8[d]
0
11
trace
7
)
trace(22[a]
0
)
0
0
4
3
1
12
3
6
2
15
0
0
0
0
0
0
0
0
–
[c]
2[b]
3
K2CO3
Cs2CO3
K3PO4
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
trace
trace
16[d]
0
trace
trace
trace
0
13
16
34
35
17
7
0
0
4
5
6
7
8
9
10
5
45[d]
9
trace
0
2
3
4
0
21
0
11
0
10
28
19[a]
0
8[a]
5
2-ethoxyethanol
0
[a] The yields were determined by the 1H NMR spectra of the mixture from the integrated ratio of each product. [b] Two equiv. of
compound 8 were used only in this reaction. [c] We did not determine the yield of 8 in this reaction; however, it proceeded almost
quantitatively. [d] The yields were roughly determined including some negligible contaminations.
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∧ ∧
Tridentate C C N Cyclometalated Complexes of Iridium
On the other hand, the undesired directed C–H bond acti- The tridentate ligand, η4-cyclooctadiene, and chlorine made
vation of 8 also proceeded to form 12 in the presence of a distorted octahedral trivalent iridium structure. The bond
base in low yields (entries 3–10).
length between the iridium and the center carbon, Ir1–C11,
Fortunately, we discovered that 10 was an intermediary was 2.002(3) Å, which was in the range of an iridium–car-
product in the generation of 9, which never formed in the bon single bond. Those between the iridium and the side
absence of base. As shown in Scheme 4, when a solution of carbon and nitrogen atoms, Ir1–C17 and Ir1–N1, were
10 was heated with K2CO3 at 200 °C for 1 or 2 h, we ob- 2.112(3) and 2.203(3) Å, respectively. These lengths are a
served two sets of signals assigned as 9 and 10 in a 2:1 ratio little longer than that of the Ir1–C11 bond length,[15] and a
1
in the H NMR spectrum of the crude mixture. By using representative list of the bond lengths and angles in 7 and
silica gel column chromatography we could isolate 9 in 61% the other structures is shown in Table 2.
yield, and the overall yield from 7 was 42 %.
Table 2. Representative bond lengths [Å] and angles [°] for 7, 10,
and 12.
Bond lengths
Bond angles
7
Ir1–Cl1
Ir1–N1
Ir1–C11
Ir1–C17
C5–C6
2.3887(8)
2.203(3)
2.002(3)
2.112(3)
1.459(4)
1.476(5)
1.404(5)
1.381(5)
Cl1–Ir1–C11
N1–Ir1–C11
N1–Ir1–C17
C11–Ir1–C17
96.83(9)
76.75(12)
152.09(12)
78.51(13)
Scheme 4. Preparation of 9.
We also tried a reaction of a bidentate ligand, 2,2Ј-bipyr- C10–C12
C18–C19
C22–C23
idyl, with which ortho-metalation does not proceed, in con-
trast to 6-phenylbipyridyl. Successfully, a simple ligand-ex-
change reaction proceeded to form iridium complex 14 in
29% isolated yield as a result of the reaction of 7 with
2 equiv. of 2,2Ј-bipyridyl in 2-ethoxyethanol at 130 °C for
20 h (Scheme 5).
10
Ir1–Cl1
Ir1–N1
Ir1–N2
Ir1–N3
Ir1–C11
Ir1–C33
C5–C6
2.4916(14)
2.050(5)
2.127(5)
1.984(5)
2.031(5)
2.019(5)
1.462(9)
1.503(9)
Cl1–Ir1–N1
Cl1–Ir1–C11
N1–Ir1–N3
N2–Ir1–C33
93.89(14)
173.53(16)
176.43(19)
160.3(2)
C10–C12
12
Ir1–N1
Ir1–N2
2.165(6)
2.160(6)
1.983(6)
2.075(7)
2.053(7)
1.900(8)
1.133(9)
1.468(10)
N1–Ir1–C11
N1–Ir1–C17
N2–Ir1–C24
Ir1–C34–O1
78.8(3)
159.2(3)
78.3(2)
174.5(6)
Ir1–C11
Ir1–C17
Ir1–C24
Ir1–C34
O1–C34
C27–C28
Scheme 5. Preparation of 14.
Characterization of Iridium Complexes 7, 9–12, and 14
The isolated iridium complexes 7, 9–12, and 14 were
1
1
characterized by H and 13C NMR spectroscopy, IR, UV,
The H NMR spectrum of 9 shown in Figure 2 has all
and ESI-MS. The structures of some complexes (7, 10–12) the signals and coupling patterns assigned by using two-
were determined by single-crystal X-ray diffraction studies. dimensional NMR spectroscopic studies. The full results
The 1H NMR spectrum for 7 demonstrated the existence of from these studies are provided in the Supporting Infor-
1
the biphenylpyridine ligand and cyclooctadiene in a 1:1 ra- mation. All the signals from both the H and 13C NMR
tio, as calculated from the integrated ratios of the assigned spectra were observed independently, thus demonstrating
proton signals in these ligands. The expected formation of its asymmetric structure. The ESI-MS spectrum of the pro-
the tridentate ligand has clearly occurred as determined by tonated compound, calculated as m/z
=
654.1521
detection of the characteristic downfield shift of the 13C (C33H23N3Ir+) and observed as m/z = 654.2411, showed no
resonances due to the two iridium-bound quaternary car- existence of chlorine, and the observed isotopic distribution
bon atoms at δ = 172.4 and 167.0 ppm. Also, the typical was in good agreement with the calculated one.
1
downfield shift of the signals due to the four protons in the
The H NMR spectrum for 10 in the aromatic region
pyridine ring Ϫ δ = 7.86–9.18 ppm in 7, down from δ = showed 23 independent signals, one more than 9. The pres-
7.41–8.71 ppm in 13 Ϫ supported the coordination of the ence of a chlorine atom close to the α-proton in one of
pyridine group. Finally, we confirmed the structure of 7 on the pyridyl groups was indicated by the appearance of a
the basis of X-ray crystallography. As shown in Figure 3 downshifted doublet signal at δ = 10.20 ppm. This was fur-
(a), the pyridylbiphenylene ligand took an almost planar ther supported by two-dimensional NMR spectroscopy and
conformation and shows the conjugated plane as expected. it was confirmed by X-ray crystallography as shown in Fig-
Eur. J. Inorg. Chem. 2011, 2869–2878
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Y. Koga, K. Matsubara et al.
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1
Figure 2. H NMR spectrum for 9 (400 MHz, in CDCl3).
ure 3 (b). The structure showed a pseudo-octahedral con-
∧
formation, composed of a chloride ligand, bidentate C N-
∧ ∧
pyridylbiphenyl, and tridentate N N C-phenylbipyridyl.
Interestingly, one of the phenyl groups in the bidentate
∧
C N-pyridylbiphenyl forms π–π stacking with the center
∧ ∧
pyridyl group of the tridentate N N C-phenylbipyridyl at
a distance of 3.9 Å. In solution, five independent H NMR
1
spectroscopic resonances due to the stacking phenyl group
suggested that the rigid conformation is the same as in the
solid state.
1
Similar signals to those for 10 were observed in the H
NMR spectrum for 11, in that the number of the protons
in 11 was 23, and a doublet signal appeared at δ =
10.24 ppm. ESI-MS spectra for 10 and 11 both showed the
typical separated patterns of the same isotopes, m/z = 654.2
and 652.2 as dechlorinated major signals. These observa-
tions indicate that 10 and 11 are structurally different iso-
1
mers. The equivalent signals in the H NMR spectrum for
11 around δ = 7.3–7.4 ppm are assigned to five protons in
a phenyl group, of which free rotation of the C–C single
bond is possible, which stands in sharp contrast to the case
of 10. Preliminary single-crystal X-ray diffraction study for
11 agreed well with these spectral observations and this is
shown in the Supporting Information.
Figure 3. ORTEP drawings of (a) 7, (b) 10, and (c) 12 (50% prob-
ability of thermal ellipsoids). All hydrogen atoms are omitted for
clarity.
Evidence for the carbonyl ligand in 12 was provided by
several spectroscopic analyses. The IR spectrum showed a
very strong single absorbance at 1995 cm–1, assigned as the
CO stretching band, and a 13C NMR spectroscopic reso-
nance in the lowest field at δ = 174 ppm due to the quater-
nary CO carbon was also observed. The ESI-MS spectrum
supported the atomic composition of [C33H22N3Ir/CO/
Na]+ for 12 as expected. Finally, the structure was con-
firmed by X-ray crystallography as shown in Figure 3 (c).
mation of a carbonyl complex of iridium in 2-ethoxyethanol
with base has previously been reported in the literature.[16]
Nineteen independent signals in the H NMR spectrum of
14 due to 19 aromatic protons indicate that there are no
non-iridium bound aromatic groups. The typical down-field
doublet signal at δ = 10.19 ppm, assigned to an α-proton
of the pyridyl group, strongly indicates the chlorine atom
remains in 14, similar to 10 and 11.
1
∧ ∧
The existence of the tridentate C C N-pyridylbiphenylene
in 12 is significant in that it shows that such coordination
modes are thermally stable in the reaction of 7 with pyridyl
ligands. We assumed that the carbonyl group in 12 was in-
troduced from the alcoholic solvents or M2CO3, in which
Reaction Mechanism to Form 10 and 9
We considered the reaction mechanism in the stepwise
M was K or Cs. A small amount of 12 is formed upon formation of 10 and then 9 from 7. As for the formation of
addition with K3PO4 (Table 1, entry 5), and the dependence 10 in the absence of the base, it is easily imagined that the
of the yield of 12 on the solvents (Table 1, entries 9 and 10) ligand-exchange reaction of η4-cyclooctadiene with the bi-
suggests that the carbonyl group can be derived from the pyridyl group in 8 proceeds to form an unknown product
solvents by means of a C–C bond-cleavage reaction. For- A as an intermediate. The formation of intermediate A was
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∧ ∧
Tridentate C C N Cyclometalated Complexes of Iridium
shown to be possible by the reaction of 7 with 2,2Ј-bipyridyl Luminescence
to form 14, a similar complex to A. However, A was not
Photoluminescent spectroscopy for the complexes 9–12
detected when the reaction was carried out at the same tem-
perature, 130 °C, as that at which 14 formed. Because free
pyridylbiphenyl and any decomposed products were not ob-
served in the crude mixture of the reaction without the base
(Table 1, entry 2), some intramolecular interconversion
could occur after ligand substitution of 7 with phenylbi-
pyridyl. Formation of an iridium(III) intermediate B
(Scheme 6) might be possible through elimination of chlo-
ride anion and pyridinium cation formed by cleavage of the
aromatic C–H bond in phenylbipyridyl from A. Formation
of the cation was partly evidenced by addition of AgOTf
into the reaction mixture to form a complex mixture and
not 10. The high reaction temperature prevented further in-
vestigation. We found that 10 is one of the intermediates for
efficient production of 9, which might be formed through
formation of an intermediate C from 10. Transmetallation
of chloride in 10 and removal of proton accompanied by
the Ir–C bond formation might form 9 as proposed in
Scheme 6. It is noteworthy that 9 is thermally more stable
than 10 in the presence of base, as expected.
and 14 was measured in CH2Cl2 (1.0ϫ 10–5 m) (Figure 4).
The wavelengths at the maximum intensity in the UV/Vis
and luminescent spectra are listed in Table 3. Remarkably,
all the cyclometalated iridium complexes except 12 have
quite unique luminescent wavelengths in the deep red
∧ ∧
(650 nm) to near infrared (730 nm) range. The C C N cy-
clometalated complexes 9 and 14 showed similar weak
broad luminescent spectra from 600 nm to more than
800 nm, in which the wavelengths at the maximum intensity
were both about 730 nm. In contrast, the luminescent spec-
tra for the carbonyl complex 12 showed a characteristic
blueshift to 525 nm as the wavelength at the maximum in-
tensity, apparently due to the existence of the acceptor, CO
ligand.[17] On the other hand, it is interesting that the wave-
lengths in the luminescent spectra for the tridentate
∧ ∧
C N N cyclometalated complexes 10 and 11 were both
650 nm, which were about 80 nm shorter than that observed
∧ ∧
in the spectra for the C C N complexes 9 and 14. The X-
ray diffraction study for 10 indicated the existence of π–
π-stacking interaction between the aromatic groups of the
bidentate pyridylbiphenylene and tridentate phenylbipyridyl
ligands. However, any influence of that interaction on the
luminescence behavior of 10 was not detected compared
with that of 11. This is a similar result to that reported
in a literature,[18] although another recent report showed a
significant effect on the luminescent properties.[19] The lu-
Scheme 6. Proposed reaction mechanism to form 10 and 9.
Although we have poor information to help us to under-
stand why the yields were quite low when the base was ini-
tially added to 7, we found that 7 is unstable in the presence
of base. Addition of K2CO3 to a solution of 7 forms many
decomposed products, such as pyridylbiphenyl 13, upon
heating at 160 °C for 1 h, whereas no decomposition oc-
curred under the same conditions without the base.
Figure 4. Photoluminescence spectra (1.0ϫ10–5 m in CH2Cl2) for
9, 10, 11, 12, and 14, for which the irradiated wavelengths were
400 nm. Another irradiation wavelength around 400 nm did not
affect the shapes of the spectra for all the compounds.
Table 3. Absorption and luminescent properties for 9–12, and 14.
Complex
Absorption
Emission
Φ[c]
[a]
λmax [nm] (ε/103 mol–1 [dm3 cm–1])
λmax [nm][b]
9
272 (36.8), 286 (32.9), 317 (19.9), 405 (12.1), 431 (11.4), 456 (8.4)
272 (32.5), 295 (26.3), 348 (12.7), 396 (5.9), 425 (4.4)
268 (46.1), 398 (35.0), 353 (11.1), 402 (5.7), 430 (4.4)
252 (47.7), 272 (40.4), 310 (21.6), 350 (14.8), 384 (9.7)
287 (36.6), 303 (24.1), 393 (10.3), 418 (10.6), 439 (8.2)
730
655
650
485, 515
725
1.5ϫ10–3
7.4ϫ10–3
9.8ϫ10–3
4.2ϫ10–2
8.5ϫ10–4
10
11
12
14
[a] Absorption data for the iridium complexes in CH2Cl2 solution at room temperature. [b] Luminescence data for the iridium complexes
in CH2Cl2 solution at room temperature. [c] Luminescence quantum yield, measured using Ru(bpy)3Cl2 as the standard (Φ = 0.028).
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Y. Koga, K. Matsubara et al.
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∧ ∧
minescence quantum yields, which were measured using orbitals, d(Ir) and π(C C N ligand), are closely located,
[Ru(bpy)3Cl2] as the standard (Φ = 0.028), were all disap- which resulted in energy transfer from both the metal and
∧ ∧
pointingly small. Such low luminescent efficiency of triden- the ligand to the π*(N N C) orbital in the other ligand.
tate cyclometalated iridium complexes has also been re- Thus they are MLCT and LLCT by irradiation. Such a
ported previously.[5d,20]
high degree of LLCT character in the excited state could
lead to the low luminescent ability of iridium in the relax-
ation process similar to a previously reported iridium
∧ ∧
Consideration for Luminescent Properties
complex that bear tridentate ligands, [Ir(N C N)-
2+ [9]
∧ ∧
(N N N)]
.
The calculated HOMO orbital in 9 showed
Although poor emission intensities of these complexes
disappointed us (for example, the quantum yield Φ of 9 was
under 0.01), the range of the wavelengths for these com-
plexes was characteristic and needs further explanation. On
the basis of DFT calculations, we compared the HOMO
and LUMO energy band gap of 9 with those of an iridium
delocalization of electron density in both the metal and the
∧ ∧
C C N ligand as shown in Figure 6.
∧ ∧
complex X that bear dpyx and dppy as N C N and
∧ ∧
C N C cyclometalated ligands, respectively. Figure 5 illus-
trates the HOMO and LUMO energy correlations of 9 and
X[21] and shows the effects of these tridentate cyclomet-
alated ligands on the frontier orbitals. The energy levels of
the center metal orbital in these complexes are the same
because they have the same numbers of carbon and nitro-
gen atoms bound to iridium. However, it is of interest that
the energy diagram suggests that the high energy levels of
Figure 6. Electron-density maps of the HOMO (left) and LUMO
(right) for 9 calculated by density functional theory (DFT) based
on B3LYP 6-31G for the ligand and LANL2DZ for iridium atom.
∧ ∧
both the π and π* orbitals in the C C N ligand, and the
∧ ∧
low energy levels of those in the N N C of 9, can induce
We also discussed a possibility for the photochemical in-
stability of 9, which could lead to low photoluminescence
intensity. A previous study demonstrated photochemical de-
composition of an iridium complex that bear tridentate
a narrower energy band gap between the HOMO (the occu-
∧ ∧
pied iridium d orbital) and LUMO (π* of N C C ligand)
than that of X. This narrow band gap may result in the
∧ ∧
∧ ∧
∧ ∧
typical redshift we have seen in the C C N cyclometalated
C N C and N C N cyclometalated ligands (X) in CH2Cl2
when irradiated with visible light for 5 min.[9] However, un-
der similar conditions to the literature, photoirradiation of
9 using 400 nm light from a 150 W xenon lamp for 5 min
did not decrease the photoluminescence intensity of 9, as
shown in Figure 7. In addition, we did not detect any
change in the 1H NMR spectra for the solution of 9 in
CDCl3 after photoirradiation for 1 h with the lamp without
any filters, thereby indicating the remarkable toughness of
9 against light, which is in sharp contrast to that of X. Thus,
we concluded that the low luminescent ability in 9 was not
derived from the photochemical decomposition process.
However, the photochemical stability of 9 is good infor-
mation for us to use in the design of new luminescent irid-
ium complexes that bear tridentate ligands.
complexes. A recent calculation study that compared some
gold complexes that bear the same tridentate ligands also
showed a higher energy of the unoccupied MO of the
∧ ∧
∧ ∧
C C N cyclometalated ligand than that of C N C li-
gand.[22]
Figure 5. Simplified schematic energy-level diagram of the iridium
complexes 9 and X. Long-wavelength emission in 9 is attributed to
a narrow-energy band gap of the MLCT between d(Ir) and
∧
∧
π*(N N C). “Double-ζ”-quality basis sets were employed for the
ligands (6-31G) and the Ir (LANL2DZ).
As for the unexpected low photoluminescence intensity
∧ ∧
in these C C N cyclometalated complexes, we considered
that one of the subsequent hypotheses that arose from the
DFT calculation results of 9, which were conducted with
double-ζ-quality basis sets for the ligands (6-31G) and Ir
(LANL2DZ), clearly explains the phenomenon. The energy
∧ ∧
level of the π orbital of the N N C ligand in 9 is lower
Figure 7. Photoluminescent spectra for 9 before (᭺) and after (᭹)
∧ ∧
than that of the π orbital of the N C N ligand in X. The photoirradiation using a 400 nm light for 5 min in CH2Cl2.
2874
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 2869–2878

∧ ∧
Tridentate C C N Cyclometalated Complexes of Iridium
0.6 mmol), lithium chloride (85 mg, 2.0 mmol), and dichlorobis(tri-
phenylphosphane)palladium (7.3 mg, 0.01 mmol) were added to a
20 mL Schlenk tube. The mixture was dissolved in toluene
(2.5 mL). The tube was refilled with argon and equipped with a
reflux condenser. The solution was heated under reflux for 15 h
with stirring. After cooling to room temperature, a saturated aque-
ous solution of potassium fluoride (2.5 mL) was added and stirred
for 30 min. After the suspension was filtered, the solution was ex-
tracted with dichloromethane (2.5 mLϫ3), dried under MgSO4,
and filtered. Removal of the solvent under reduced pressure gave a
yellow liquid. Compound 6 was purified after silica gel column
chromatography by eluting with hexane, as a yellow liquid (110 mg,
Conclusion
∧ ∧
New C C N cyclometalated iridium complexes that bear
tridentate 3-pyridylbiphenyl were synthesized by means of
directed oxidative addition of the C–C bond of pyridylbi-
phenylene with chloro(1,5-cyclooctadiene)iridium(I) dimer,
[{IrCl(cod)}2]. The reaction of the iridium complex,
∧ ∧
[IrCl(cod)(C C N-pyridylbiphenyl)] (7) with 6-phenyl-2,2Ј-
bipyridyl in the presence of base at 130–200 °C formed sev-
eral products, most of which were isolated and structurally
characterized. [Ir(C C N-pyridylbiphenyl)(C N N-phen-
ylbipyridyl)] (9) and [IrCO(C C N-pyridylbiphenyl)(N C-
∧ ∧
∧ ∧
∧ ∧
∧
1
92% yield). H NMR (CDCl3): δ = 8.71 (d, J = 4.4 Hz, 1 H, H6-
∧ ∧
py), 7.76 (t, J = 7.6 Hz, 1 H, H4-py), 7.63 (d, J = 8.0 Hz, 1 H, H3-
py), 7.41 (d, J = 8.4 Hz, 1 H, H2-biph), 7.22 (t, J = 7.6 Hz, 1 H,
H5-py), 6.95–6.93 (m, 1 H, H6-biph), 6.86 (t, J = 7.8 Hz, 1 H, H3-
biph), 6.82–6.80 (m, 2 H, H5/8-biph), 6.69 (m, 1 H, H7-biph), 6.66
(d, J = 6.8 Hz, 1 H, H4-biph) ppm. 13C NMR (CDCl3): δ = 154.7
(C2-py), 151.5 (quat.), 151.4 (quat.), 151.3 (quat.), 149.7 (C6-py),
149.1 (quat.), 136.4 (C4-py), 130.3 (C1-biph), 129.0 (C3-biph), 128.7
(C8-biph), 128.3 (C5-biph), 126.1 (C2-biph), 122.1 (C5-py), 120.7
(C3-py), 118.8 (C6-biph), 117.3 (C4-biph), 117.1 (C7-biph) ppm.
GC–MS (EI): m/z calcd. for C17H11N: 229.089; found 229.018
[M+]. C17H11N + H2O (247.29): calcd. C 82.57, H 5.30, N 5.66;
found C 82.30, H 5.01, N 5.96.
phenylbipyridyl)] (12) were good examples of C C N cy-
clometalated complexes. Two structural isomers of
∧
∧ ∧
∧ ∧
[IrCl(C N-pyridylbiphenyl)(C N N-phenylbipyridyl)] (10
and 11) were two examples of C N N cyclometalated com-
plexes. Compound 9 was afforded in good yield through the
formation of the intermediate 10, which can be isolated in
high yield from the reaction of 7 with 6-phenyl-2,2Ј-bipyr-
idyl (2 equiv.) in the absence of base. The reaction of 7 with
∧ ∧
2,2Ј-bipyridyl also gave a C C N cyclometalated complex,
∧
∧ ∧
[IrCl(N N-bipyridyl)(C C N-pyridylbiphenyl)] (14). The
photoluminescent performances of the isolated complexes
were also studied. Despite low luminescent intensity, 9 and
14 showed luminescence at longer wavelengths than that of
Preparation of 7: 1-(Pyridine-2-yl)biphenylene (0.71 g, 3.1 mmol),
[{IrCl(cod)}2] (1.0 g, 1.6 mmol), and 1,2-dichloroethane (15 mL)
were added to a 20 mL Schlenk tube. The solution was stirred at
room temperature for 30 min and then at 95 °C for 3 h. After cool-
ing to room temperature, the solvent was removed under reduced
pressure. The residual orange solid was dissolved in dichlorometh-
ane. Addition of ethyl acetate lead to precipitation of the product
∧ ∧
previous C N C cyclometalated iridium complexes, due to
∧ ∧
the high π*-orbital energy of C C N pyridylbiphenyl li-
gand.
Experimental Section
1
7 (1.66 g, 92% yield). H NMR (CDCl3): δ = 9.18 (d, J = 5.8 Hz,
General: All experiments for synthesis of the iridium complexes
were carried out under an argon atmosphere using standard
Schlenk techniques unless otherwise noted. The solvents, glycerol,
2-ethoxyethanol, and ethylene glycol, were stored under 4 Å molec-
ular sieves and degassed before use. Other reagents were used as
received. Column chromatography of products was carried out
using silica gel [Kanto Kagaku, silica gel 60N (spherical, neutral)].
Preparative TLC was prepared with the same silica gel on a glass
plate (20 cmϫ20 cm). The 1H NMR spectra were taken with a
VARIAN Mercury Y plus 400 MHz spectrometer at room tem-
perature. Chemical shifts (δ) were recorded in ppm from the solvent
signal. IR spectra were recorded in cm–1 with a Perkin–Elmer Spec-
trum One spectrometer equipped with a universal diamond ATR.
UV/Vis spectra were measured with a JASCO V-550 UV/Vis spec-
trophotometer. Photoluminescent spectra were recorded with a Hi-
tachi F-7000 fluorescence spectrophotometer. All the samples were
dissolved in CH2Cl2. The quantum yields were calculated from the
luminescent spectra, calibrated by the standard solution, [Ru-
(bpy)3Cl2] solution in water (quantum yield 0.028). The elemental
analysis was carried out with a YANACO CHN Corder MT-5
auto-sampler. Electrospray ionization time-of-flight mass spec-
trometry (ESI-TOF MS) was carried out with a JEOL JMS-T100
mass spectrometer. The sample solutions in methanol were directly
infused using methanol as solvent stream. The synthesis of the or-
ganic compounds 2–4 was carried out according to the literature.[23]
Although the synthesis of 5 has been reported previously,[24] we
developed an alternative route to 5 from 4, details of which are
shown in the Supporting Information.
∧ ∧
∧ ∧
∧ ∧
1 H, H6-C C N), 7.97–7.90 (m, 2 H, H3/4-C C N), 7.88–7.86 (m,
∧ ∧
∧ ∧
1 H, H6-C C N), 7.61–7.55 (m, 2 H, H3-C C N/H3-C C N),
∧ ∧
7.52 (d, J = 7.8 Hz, 1 H, H5-C C N), 7.37 (t, J = 6.2 Hz, 1 H,
∧ ∧ ∧ ∧
H5-C C N), 7.20–7.15 (m, 2 H, H4/5-C C N), 7.12 (t, J = 7.6 Hz,
∧ ∧
1 H, H4-C C N), 5.88–5.80 (m, 1 H, CH-cod), 5.16–5.08 (m, 1 H,
CH-cod), 3.16–3.06 (m, 2 H, CH-cod), 2.92–2.72 (m, 2 H, CH2-
cod), 2.45–2.34 (m, 2 H, CH2-cod), 2.33–2.13 (m, 2 H, CH2-cod),
2.01–1.78 (m, 2 H, CH2-cod) ppm. 13C NMR (CDCl3): δ = 172.4
∧ ∧
∧ ∧
∧ ∧
∧ ∧
∧ ∧
(C1-C C N), 167.0 (C1-C C N), 152.3 (C2-C C N), 151.5 (C6-
∧ ∧
C C N), 150.1 (C2-C C N), 140.6 (C6-C C N), 138.7 (C2-
∧ ∧ ∧ ∧ ∧ ∧
C C N), 138.4 (C4-C C N), 135.2 (C6-C C N), 127.4 (C4-
∧ ∧ ∧ ∧ ∧ ∧
C C N), 123.8 (C4-C C N), 123.8 (C5-C C N), 122.9 (C4-
∧ ∧ ∧ ∧ ∧ ∧
C C N), 121.6 (C3-C C N), 121.6 (C3-C C N), 121.3 (C5-
∧ ∧
∧ ∧
C C N), 120.0 (C3-C C N), 105.3 (CH-cod), 104.4 (CH-cod),
85.09 (CH-cod), 79.26 (CH-cod), 33.64 (CH2-cod), 31.54 (CH2-
cod), 27.95 (CH2-cod), 26.34 (CH2-cod) ppm. ESI-MS: m/z calcd.
for [C26H27NClIr + H]+: 566.123; found 566.142. C25H23ClIrN
(565.13): calcd. C 53.13, H 4.10, N 2.48; found C 52.91, H 4.03, N
2.36.
General Reactions of 7 with 1-Phenylbipyridine (8): In a typical ex-
ample,
7
(28 mg, 0.05 mmol), 1-phenylbipyridine (13 mg,
0.055 mmol), K2CO3 (35 mg, 0.25 mmol), and glycerol (1.0 mL)
were added to a 20 mL Schlenk tube. The solution was stirred at
200 °C for 1 h. After cooling, water (5 mL) was added and ex-
tracted with dichloromethane (5 mLϫ3). The solution was dried
under Na2SO4 and filtered. Removal of the solvent under reduced
pressure gave a brown solid. Separation of the products using silica
gel column chromatography by eluting with dichloromethane/
methanol gave 9–13.
Preparation of 1-(Pyridine-2-yl)biphenylene (6): Compound
(120 mg, 0.5 mmol), 2-(tributylstannyl)pyridine (230 mg,
5
Eur. J. Inorg. Chem. 2011, 2869–2878
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2875

Y. Koga, K. Matsubara et al.
FULL PAPER
Compound 11: (orange crystals, trace amount): H NMR (CDCl3):
1
Schlenk tube. The solution was stirred at 200 °C for 1 h. After cool-
∧ ∧
δ = 10.2 (d, J = 6.0 Hz, 1 H, H6-C C N), 8.03 (t, J = 8.2 Hz, 2 ing, water (5 mL) was added and extracted with dichloromethane
∧ ∧
∧ ∧
H, H4-C C N/H3-N N C), 7.92 (d, J = 6.0 Hz, 1 H, H6- (5 mLϫ3). The solution was dried under Na2SO4 and filtered. Re-
∧
∧
∧
∧
∧
∧
∧ ∧
∧ ∧
∧ ∧
N N C), 7.89–7.83 (m,
3
3
H, H4-C C N/H5-N N C/H5-
moval of the solvent under reduced pressure gave a brown solid.
Silica gel column chromatography by eluting with dichloromethane
∧ ∧
N N C), 7.80–7.74 (m,
H, H3-C C N/H4-N N C/H4-
∧ ∧
N N C), 7.55 (d, J = 7.6 Hz, 1 H, H3-N N C), 7.43 (d, J =
gave 9 (20 mg, 61% yield). H NMR (CDCl3): δ = 8.06–8.01 (m, 3
1
∧ ∧
∧ ∧
∧
∧
∧ ∧
8.0 Hz, 2 H, H2/6-C C N), 7.38–7.22 (m, 5 H, H3/5-C C N/H5- H, H3-N N C/H3/5-N N C), 7.94 (d, J = 8.0 Hz, 1 H, H3-
∧
∧
∧
∧
∧
∧ ∧
H, H5-C C N/H5/6
-
∧ ∧
∧ ∧
C N N/H3-N N C), 6.89–6.81 (m,
3
C C N), 7.84 (t, J = 6.8 Hz, 1 H, H4-N N C), 7.77–7.73 (m, 2
∧
∧
∧
∧ ∧
∧ ∧
N N C), 6.34 (d, J = 7.2 Hz, 1 H, H6-N N C), 6.23 (d, J =
H, H3/5-C C N), 7.68 (d, J = 5.6 Hz, 1 H, H6-N N C), 7.63–7.56
∧ ∧
∧ ∧
∧
∧
∧ ∧
7.2 Hz, 1 H H6-C C N) ppm. 13C NMR (CDCl3): δ = 167.8 (m, 3 H, H3-C C N/H4-N N C/H3-N N C), 7.50 (t, J = 7.4 Hz,
∧ ∧ ∧ ∧
1 H, H4-C C N), 7.44 (d, J = 5.6 Hz, 1 H, H6-C C N), 7.30–7.26
(quat.), 166.6 (quat.), 157.7 (quat.), 155.3 (quat.), 151.2, 149.9,
149.8 (quat.), 147.4 (quat.), 144.9 (quat.), 143.6 (quat.), 141.6
(quat.), 137.5, 137.0, 136.3, 133.9 (quat.), 132.5, 131.0, 130.7, 128.6,
∧ ∧
∧ ∧
(m, 1 H, H4-C C N), 6.89 (t, J = 9.8 Hz, 1 H, H5-N N C), 6.74
∧ ∧
∧ ∧
(t, J = 7.6 Hz, 2 H, H4-C C N/H4-N N C), 6.62 (t, J = 6.2 Hz,
∧ ∧
∧ ∧
∧ ∧
∧ ∧
128.5, 126.8 (C2/6-C C N), 126.4 (C3/5-C C N), 126.3, 125.3, 1 H, H5-C C N), 6.56 (t, J = 8.0 Hz, 1 H, H5-N N C), 6.41 (t, J
∧ ∧
∧ ∧
122.8, 122.4, 122.2, 121.4, 118.5, 118.2, 117.2 ppm. ESI-MS: m/z
calcd. for [C33H23N3ClIr
C33H23ClIrN3 + H2O (707.24): calcd. C 56.04, H 3.56, N 5.94; = 186.7 (quat.), 168.0 (quat.), 164.0 (quat.), 158.3 (quat.), 156.1
= 7.2 Hz, 1 H, H5-C C N), 6.26 (t, J = 7.6 Hz, 1 H, H6-N N C),
∧ ∧
Cl]+: 654.152; found 654.148. 5.94 (d, J = 7.6 Hz, 1 H, H6-C C N) ppm. 13C NMR (CDCl3): δ
–
found C 56.20, H 3.65, N 5.83.
(quat.), 152.7 (quat.), 152.6, 152.4 (quat.), 151.3 (quat.), 149.7,
148.2 (quat.), 144.0 (quat.), 138.9 (quat.), 136.3, 135.5, 135.5, 134.5,
132.2, 130.1, 126.1, 124.8, 124.5, 122.3, 120.9, 120.5, 120.2, 120.1,
119.9, 119.8, 119.7, 119.7, 119.0, 117.3, 116.2 ppm. ESI-MS: m/z
calcd. for [C33H22N3Ir + H]+: 654.152; found 654.234. C33H22IrN3
+ H2O (670.78): calcd. C 59.09, H 3.61, N 6.26; found C 59.38, H
3.87, N 6.01.
1
Compound 12: (yellow crystals, 4% yield): H NMR (CDCl3): δ =
∧
∧
9.31 (d, J = 5.6 Hz, 1 H, H6-N N C), 8.74 (d, J = 8.4 Hz, 1 H,
∧
∧
∧ ∧
H3-N N C), 8.11 (t, J = 7.8 Hz, 1 H, H4-N N C), 7.94 (t, J =
∧ ∧
∧
∧
8.4 Hz, 2 H, H3/6-C C N), 7.88 (d, J = 7.2 Hz, 2 H, H2/6-N N C),
∧ ∧
7.71 (t, J = 7.2 Hz, 1 H, H4-C C N), 7.70 (d, J = 7.6 Hz, 1 H,
∧ ∧ ∧ ∧
H3-C C N), 7.65 (d, J = 8.0 Hz, 1 H, H5-C C N), 7.60 (d, J =
∧ ∧
∧ ∧
7.6 Hz, 1 H, H3-C C N), 7.52 (t, J = 6.4 Hz, 1 H, H5-N N C),
Preparation of 14: Compound 7 (0.028 g, 0.050 mmol), 2,2Ј-bipyr-
idine (0.016 g, 0.1 mmol), and 2-ethoxyethanol (5 mL) were added
to a 20 mL Schlenk tube. The solution was stirred at 130 °C for
20 h. After the solvents were evaporated under reduced pressure, a
residual brown solid was obtained. Silica gel column chromatog-
raphy by eluting with dichloromethane and methanol in a 98:2 ratio
and subsequent preparative TLC afforded red crystals of 14
∧ ∧
∧
∧
∧ ∧
7.39–7.30 (m, 3 H, H4-C C N/H3/5-N N C), 7.27 (t, 1 H, H4-
∧
∧
N N C), 7.04 (d, J = 8.0 Hz, 1 H H5-N N C), 6.98–6.89 (m, 2
∧ ∧
∧ ∧
∧ ∧
H, H4-C C N/H5-C C N), 6.68 (t, J = 7.4 Hz, 1 H, H5-C C N),
∧ ∧
6.59 (d, J = 7.2 Hz, 1 H, H6-C C N), 6.42 (d, J = 8.0 Hz, 1 H,
∧
∧
H4-N N C) ppm. 13C NMR (CDCl3): δ = 174.1 (CO), 166.9
(quat.), 164.6 (quat.), 164.2 (quat.), 162.1 (quat.), 159.9 (quat.),
154.4 (quat.), 151.6, 151.4 (quat.), 151.0 (quat.), 150.8, 141.4, 139.9
(quat.), 139.7 (quat.), 137.4, 137.4 (quat.), 137.2, 134.3, 128.4
1
(8.8 mg, 29% yield). H NMR (CDCl3): δ = 10.2 (d, J = 5.2 Hz, 1
∧
∧
H, H6-N N), 8.19 (d, J = 8.4 Hz, 1 H, H3-N N), 8.08 (t, J =
∧
∧
7.8 Hz, 1 H, H4-N N), 7.91 (d, J = 8.0 Hz, 1 H, H3-N N), 7.87
∧ ∧
∧ ∧
(C2/6-C C N), 128.0, 126.3, 125.0 (C3/5-C C N), 123.1, 123.1,
∧ ∧ ∧ ∧
(d, J = 7.6 Hz, 1 H, H3-C C N), 7.83–7.76 (m, 3 H, H6-C C N/
122.8, 122.2, 121.8, 121.5, 121.2, 121.0, 120.0 ppm. IR: ν = 1995
˜
∧
∧
∧ ∧
H5-N N/H4-N N), 7.59 (d, J = 6.6 Hz, 3 H, H3/5-C C N/H6-
(νCO) cm–1. ESI MS: m/z calcd. for [C34H23N3OIr + Na]+: 704.129;
found 704.224. C34H22N3OIr + H2O (698.79): calcd. C 58.44, H
3.46, N 6.01; found C 58.30, H 3.72, N 5.71.
∧
∧ ∧
N N), 7.53 (d, J = 7.2 Hz, 1 H, H3-C C N), 7.42 (t, J = 7.8 Hz,
∧ ∧ ∧ ∧
1 H, H4-C C N), 7.15 (t, J = 7.6 Hz, 1 H, H4-C C N), 6.89 (t, J
∧
∧ ∧
= 6.4 Hz, 1 H, H5-N N), 6.80–6.74 (m, 2 H, H4-C C N/H5-
∧ ∧
∧ ∧
C C N), 6.59 (t, J = 7.4 Hz, 1 H, H5-C C N), 6.22 (d, J = 7.2 Hz,
Preparation of 10: The product was similarly obtained from 7
(28 mg, 0.05 mmol) and 1-phenylbipyridine (26 mg, 0.11 mmol) in
glycerol (1.0 mL). The red crystals of 10 were obtained from the
dichloromethane/ethyl acetate solution (0.24 g, 69% yield). 1H
∧ ∧
1 H, H6-C C N) ppm. 1H NMR ([D6]DMSO): δ = 9.84 (d, J =
∧
∧
5.0 Hz, 1 H, H6-N N), 8.77 (d, J = 8.2 Hz, 1 H, H3-N N), 8.49
∧
∧
(d, J = 8.2 Hz, 1 H, H3-N N), 8.34 (t, J = 7.2 Hz, 1 H, H4-N N),
∧ ∧
NMR (CDCl3): δ = 10.20 (d, J = 8.0 Hz, 1 H, H6-C C N), 8.06
∧ ∧
8.17 (d, J = 8.1 Hz, 1 H, H3-C C N), 8.06 (t, J = 6.5 Hz, 1 H,
∧ ∧
∧ ∧
(d, J = 6.8 Hz, 1 H, H3-C C N), 7.90–7.82 (m, 2 H, H4-C C N/
∧
∧ ∧
∧
H5-N N), 7.84–7.67 (m, 4 H, H4/6-C C N/H4/6-N N), 7.51 (d, J
∧
∧
∧ ∧
H6-N N C), 7.80–7.75 (m, 2 H, H3/5-C C N), 7.70 (d, J = 8.0 Hz,
∧ ∧
∧ ∧
= 7.4 Hz, 1 H, H3-C C N), 7.47 (d, J = 5.8 Hz, 1 H, H5-C C N),
∧ ∧
∧ ∧
∧ ∧
∧ ∧
1 H, H6-C C N), 7.41 (t, J = 8.8 Hz, 2 H, H3-N N C/H3-
∧ ∧
7.40 (d, J = 7.4 Hz, 1 H, H3-C C N), 7.13–7.02 (m, 3 H, H4-
∧
∧
∧ ∧
N N C), 7.30–7.17 (m,
4
4
H, H4-C C N/H5-C C N/H4/5
-
∧ ∧
∧ ∧
∧
C C N/H5-C C N/H5-N N), 6.64 (t, J = 7.3 Hz, 1 H, H4-
∧
∧
∧
∧
∧ ∧
N N C), 6.94–6.78 (m,
H, H4/5-C C N/H4-N N C/H5-
∧ ∧
∧ ∧
C C N), 6.42 (t, J = 7.3 Hz, 1 H, H5-C C N), 5.99 (d, J = 7.2 Hz,
∧ ∧
∧ ∧
N N C), 6.73 (t, J = 7.4 Hz, 2 H, H3-C C N/H4-N N C), 6.40
∧ ∧
1 H, H6-C C N) ppm. 13C NMR ([D6]DMSO): δ = 174.5 (quat.),
∧ ∧
(d, J = 7.5 Hz, 1 H, H4-C C N), 6.34 (d, J = 7.4 Hz, 1 H, H5-
166.4 (quat.), 158.0 (quat.), 156.4 (quat.), 155.2 (quat.), 152.2,
151.4 (quat.), 150.2, 148.2, 145.3 (quat.), 140.5 (quat.), 138.1, 137.7,
135.9, 133.6, 127.9, 127.2, 125.1, 124.0, 123.7, 122.6, 121.9, 121.8,
121.3, 120.2, 120.1, 119.8 ppm. ESI-MS: m/z calcd. for
[C27H19N3ClIr + Na]+: 636.079; found 636.097. C27H19ClN3Ir
(613.13): calcd. C 52.89, H 3.12, N 6.85; found C 53.06, H 3.24, N
6.57.
∧
∧
∧ ∧
N N C), 6.16 (d, J = 7.2 Hz, 1 H, H3-N N C), 6.08 (d, J =
∧
∧
7.5 Hz, 1 H, H6-N N C) ppm. 13C NMR (CDCl3): δ = 167.6
(quat.), 167.0, 159.4 (quat.), 155.7 (quat.), 152.2, 150.0 (quat.),
150.0, 148.1 (quat.), 146.7 (quat.), 145.6 (quat.), 144.5 (quat.),
140.9 (quat.), 137.4 (quat.), 136.6, 136.3, 132.4, 132.3, 130.4, 129.3,
128.0, 127.4, 126.5, 126.2, 125.9, 124.9, 123.0, 122.6, 122.2, 121.6,
120.6, 119.0, 118.2, 117.5 ppm. ESI MS: m/z calcd. for
X-ray Crystallography: Single crystals of 7, 10, and 12 for X-ray
diffraction studies were grown at –30 °C from the dichloromethane/
methanol solutions. All the data were collected at 123 K with a
Rigaku Saturn CCD diffractometer with confocal mirror using
graphite-monochromated Mo-Kα radiation (λ = 0.71070 Å). Data
reductions of the measured reflections were carried out using the
[C33H23N3ClIr – Cl]+: 654.152; found 654.215. C33H23ClIrN3
+
H2O (707.24): calcd. C 56.04, H 3.56, N 5.94; found C 56.05, H
3.56, N 6.02.
Preparation of 9: Compound 10 (35 mg, 0.05 mmol), K2CO3
(35 mg, 0.25 mmol), and glycerol (1.0 mL) were added to a 20 mL
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Eur. J. Inorg. Chem. 2011, 2869–2878

∧ ∧
Tridentate C C N Cyclometalated Complexes of Iridium
Table 4. Crystallographic and measurement data for 7, 10, and 12.
7
10
12
Formula (Mr)
Dimensions [mm]
Crystal system / space group
a [Å]
b [Å]
c [Å]
C25H23NClIr (565.14)
0.15ϫ0.10ϫ0.10
monoclinic / P21/c
13.471(3)
8.2199(15)
17.515(4)
99.2534(8)
1914.1(6)
4
1.961
123(1)
7.126
1096
C33H23N3ClIr (689.19)
0.12ϫ0.10ϫ0.05
monoclinic / P21/c
15.170(4)
11.074(2)
16.250(4)
109.3040(10)
2576.5(10)
4
1.777
123(1)
5.314
1344
C34H22N3OIr (680.75)
0.30ϫ0.04ϫ0.02
orthorhombic / P212121
12.0239(11)
12.1198(13)
17.712(2)
β [°]
V [Å3]
2581.1(5)
4
1.752
123(1)
5.206
1328
Z
Dcalcd. [gcm–3]
T [K]
μcalcd. [mm–1]
F (000)
Scan type
2θmax [°]
ω
55.0
ω
55.0
ω
55.0
Independent reflections
Reflections used [IϾ2σ(I)]
Variables
4388 [R(int) = 0.0477]
4080
254
5904 [R(int) = 0.0826]
5367
343
5746 [R(int) = 0.0344]
5444
352
GOF[a] on F2
R1/wR2 [IϾ2σ(I)][b]
R1/wR2 (all)[c]
ρmax [eÅ–3]
1.061
1.119
1.087
0.0251/0.0576
0.0281/0.0594
1.662 and –0.936
0.0456/0.1068
0.0517/0.1111
2.052 and –1.391
0.0441/0.0781
0.0478/0.0809
2.420 and –1.172
[a] GOF = [Σw(F2o – Fc2)2/(N – P)]1/2. [b] R(F) = Σ||Fo| – |Fc||/Σ|Fo|. [c] wR(F2) = [Σw(F2o – Fc2)2/Σw(F2o)2]1/2
.
[2]
[3]
CrystalStructure (ver. 3.8) software package. The structures were
solved by direct methods (SIR97)[25] and refined by full-matrix le-
ast-squares fitting based on F2 using the PC version of SHELXL
97-2.[26] All non-hydrogen atoms were refined with anisotropic dis-
placement parameters. All hydrogen atoms were located at ideal
positions and were included in the refinement, but were restricted
to ride on the atom to which they were bonded. The crystallo-
graphic and measurement data for these compounds are listed in
Table 4.
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cle): Experimental details for 5, 13C and two-dimensional NMR
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Acknowledgments
We thank Prof. Satoshi Kawata of Fukuoka University for the X-
ray crystallography of compound 11.
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Received: January 16, 2011
Published Online: May 17, 2011
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