Carboxylate ligand-induced intramolecular C-H bond activation of iridium complexes with N -phenylperimidine-based carbene ligands

Article abstract of DOI:10.1021/om100604u

We report the synthesis and structure of iridium(I) complexes with N,N′-disubstituted perimidine carbene ligands and halides or carboxylate ligands. Iodo-, chloro-, and acetate-Ir(carbene)(cod) complexes were selectively prepared by changing the bases and silver salts. Intramolecular C-H bond activation to prepare a cyclometalated Ir(III) complex, (C^-C:) ₂Ir(OAc) (6), where C^-C: is a cyclometalated perimidine carbene ligand, was achieved using a carboxylate-ligated iridium complex; otherwise, C-H activation did not proceed. Acetate-Ir(carbene)(cod) (3c) reacted with benzoic anhydride at room temperature to afford benzoate-Ir(carbene)(cod) (3d). A perimidine-carbene- and phenylpyridine-ligated Ir(III) complex, (C ^-C:)(C^-N)Ir(OCOR) (8), where C^-N is a cyclometalated phenylpyridine ligand, was isolated in good yield by mixing 3c or 3d and phenylpyridine under reflux in toluene. On the basis of the formation of 1,3-cyclooctadiene from the reaction mixture, we propose the following reaction mechanism for the intramolecular C-H activation: carboxylate-induced C-H bond activation and subsequent pyridine- or carbene-directed C-H bond oxidative addition, followed by the isomerization of 1,5-cyclooctadiene and reaction with carboxylic acid produces (C^-C:)(N^-C:)Ir(OCOPh). The cyclometalated complex 6 reacts with sodium acetylacetonate to form (C ^-C:)₂Ir(acac) (11), which exhibits phosphorescent emission at _max = 555 nm (τ = 0.65 μs, φ_PL = 0.0018) in CH₂Cl₂ solution at room temperature.

Full text of DOI:10.1021/om100604u

4120 Organometallics 2010, 29, 4120–4129
DOI: 10.1021/om100604u
Carboxylate Ligand-Induced Intramolecular C-H Bond Activation of
Iridium Complexes with N-Phenylperimidine-Based Carbene Ligands
Hayato Tsurugi,† Shingo Fujita,† Gyeongshin Choi,† Tsuneaki Yamagata,† Syoji Ito,‡
Hiroshi Miyasaka,‡ and Kazushi Mashima*,†
†Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka
560-8531, Japan, and ‡Division of Frontier Materials Science, Graduate School of Engineering Science,
Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan
Received June 22, 2010
We report the synthesis and structure of iridium(I) complexes with N,N0-disubstituted perimidine
carbene ligands and halides or carboxylate ligands. Iodo-, chloro-, and acetate-Ir(carbene)(cod)
complexes were selectively prepared by changing the bases and silver salts. Intramolecular C-H
bond activation to prepare a cyclometalated Ir(III) complex, (C∧C:)2Ir(OAc) (6), where C∧C: is a
cyclometalated perimidine carbene ligand, was achieved using a carboxylate-ligated iridium com-
plex; otherwise, C-H activation did not proceed. Acetate-Ir(carbene)(cod) (3c) reacted with benzoic
anhydride at room temperature to afford benzoate-Ir(carbene)(cod) (3d). A perimidine-carbene- and
phenylpyridine-ligated Ir(III) complex, (C∧C:)(C∧N)Ir(OCOR) (8), where C∧N is a cyclometalated
phenylpyridine ligand, was isolated in good yield by mixing 3c or 3d and phenylpyridine under reflux
in toluene. On the basis of the formation of 1,3-cyclooctadiene from the reaction mixture, we propose
the following reaction mechanism for the intramolecular C-H activation: carboxylate-induced C-H
bond activation and subsequent pyridine- or carbene-directed C-H bond oxidative addition,
followed by the isomerization of 1,5-cyclooctadiene and reaction with carboxylic acid produces
(C∧C:)(N∧C:)Ir(OCOPh). The cyclometalated complex 6 reacts with sodium acetylacetonate to form
(C∧C:)2Ir(acac) (11), which exhibits phosphorescent emission at λmax = 555 nm (τ = 0.65 μs, ΦPL
=
0.0018) in CH2Cl2 solution at room temperature.
Introduction
reactions of aromatic and aliphatic C-H bonds2 but also
in highly efficient organometallic-based light-emitting de-
vices possessing bis- and tris-cyclometalated structures with
heavy metal ions,3 such as iridium and platinum. Thus, the
cyclometalation reaction is a key step in both efficient
catalysis and material synthesis, and heteroatom-directed
intramolecular C-H bond activation has been considered
the most straightforward synthetic strategy.
Intramolecular C-H bond activation to produce cyclo-
metalated complexes has been intensively investigated since
the first reports of nickel and platinum complexes in the
1960s.1 This research area has recently attracted increasing
interest because cyclometalated organometallic compounds
are involved not only in various direct functionalization
The use of heteroatoms as a precoordination site before
activation of a C-H bond is a general strategy, and the
carbene-directed C-H bond activation reaction was recently
used as a functional group suitable as a precoordination site
*Corresponding author. E-mail: mashima@chem.es.osaka-u.ac.jp.
Fax: 81-6-6850-6245.
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pubs.acs.org/Organometallics
Published on Web 08/25/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 18, 2010 4121
Chart 1. Cyclometalated Iridium Complexes with Five-Mem-
bered N-Heterocyclic Carbenes
Scheme 1. Preparation of Dissymmetric Peridinium Salts
to prepare phosphorescent cyclometalated iridium com-
plexes that possess a five-membered N-heterocyclic carbene
framework (Chart 1, A-C).4,5 Richeson et al. reported that
six-membered perimidine-based carbene ligands increase
steric congestion and electron-donating ability compared
to five-membered carbene ligands.6 Together with the fact
that the heteroaromatic-directed C-H bond activation re-
action highly depends on the ring size of the hetero-
aromatics,7 we anticipated that perimidine carbene ligands
would affect the intramolecular C-H bond activation reac-
tion of iridium complexes as well as the phosphorescent
properties of the resulting cyclometalated iridium com-
plexes. In fact, most iridium complexes with cyclometalated
phenylcarbene ligands are prepared in a one-pot manner:
simple treatment of IrCl3 or Ir(I) species with silver salt,
carbenium salt, and base in 2-ethoxyethanol produces bis-/
tris(cyclometalated) iridium complexes with five-membered
carbene complexes,4b,c whereas cyclometalation of perimi-
dine carbene ligands is not achieved in a one-pot procedure.
Herein we report the synthesis of iridium complexes
supported by six-membered perimidine carbene ligands
and their intramolecular C-H bond activation reaction. In
contrast to the previously reported five-membered imida-
zole-based carbene complexes, introduction of a carboxylate
ligand to the iridium atom was indispensable for the C-H
bond activation reaction, consistent with recent studies of
direct coupling reactions via C-H bond activation where the
anionic ligands attached to the metal center significantly
accelerated the heteroaromatic-directed C-H bond activation
reaction.8 To clarify the reaction mechanism for the formation
of bis(cyclometalated)iridium complexes, (C∧C:)2IrX (C∧C: =
a cyclometalated perimidine carbene ligand), we conducted a
reaction of carboxylate-Ir(MeNPhNcarbene)(cod) with phenyl-
pyridine, which led to a perimidine-carbene- and phenylpyri-
dine-ligated Ir(III) complex, (C∧C:)(C∧N)Ir(OCOR), where
C∧N is a cyclometalated phenylpyridine ligand. Furthermore,
we prepared an acetylacetonate derivative, (C∧C:)2Ir(acac)
(acac = acetylacetonato), that exhibited phosphorescent emis-
sion at room temperature.
Results and Discussion
Synthesis of Perimidinium Salts as Precursors of N-Hetero-
cyclic Carbene Ligands. The synthesis of dissymmetric peri-
midinium salts is outlined in Scheme 1. Because the perimidine
motif has two types of nitrogen atoms, amine and imine atoms,
stepwise substitution reactions at two nitrogen atoms were easily
conducted. A Cu-catalyzed N-phenylation reaction afforded
N-phenylperimidine,9 which was treated with MeI and iPrI to
give the corresponding salts 1a and 1b. On the other hand,
N-benzyl-N-methyl derivative 2 was synthesized in a one-pot
reaction of the first N-methylation in the presence of KOH
followed by N-benzylation by PhCH2Cl under refluxing
conditions. Both reactions produced perimidinium salts 1
and 2 in moderately good yields, which were spectroscopically
characterized.
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Inorg. Chem. 2005, 44, 7992. (c) Tsuchiya, K.; Yagai, S.; Kitamura, A.;
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2008, 130, 13285, and references therein.
Synthesis and Characterization of Halide-Ir(carbene)(cod)
Complexes. The general synthesis method of late transition
metal carbene complexes is based on the pregeneration of
neutral carbene ligands using an appropriate base or silver
carbene complexes as carbene transfer reagents by treatment
with silver oxide before complexation to the metals.10 Ac-
cording to the reported procedure for forming perimidine-
based carbenes,6 we conducted the reaction of [IrCl(cod)]2
with LiN(SiMe3)2 in the presence of excess perimidinium salt
1a in THF at room temperature. After extraction with
CH2Cl2, an iridium complex with the perimidine carbene
(8) (a) Davis, D. L.; Al-Duaij, O.; Fawcett, J.; Giardiello, M.; Hilton,
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Lafrance, M.; Gorelsky, S. I.; Fagnou, K. J. Am. Chem. Soc. 2007, 129,
(9) deLange, B.; Lambers-Verstappen, M. H.; van de Vondervoort,
L. S.; Sereinig, N.; de Rijk, R.; de Vries, A. H. M.; de Vries, V. J. G.
Synlett 2006, 18, 3105.
(10) (a) Bourissou, D.; Guerret, O.; Gabbai, F. P.; Bertrand, G.
ꢀ
ꢀ
14570. (l) Liegault, B.; Lapointe, D.; Caron, L.; Vlassova, A.; Fagnou, K. J.
Chem. Rev. 2000, 100, 39. (b) Díez-Gonzalez, S.; Marion, N.; Nolan, S. P.
Org. Chem. 2009, 74, 1826.
Chem. Rev. 2009, 109, 3612.

4122 Organometallics, Vol. 29, No. 18, 2010
Tsurugi et al.
Scheme 2. Synthesis of (Iodo)- and (Chloro)Ir(carbene)(cod)
Complexes
Figure 1. ORTEP drawing of the molecular structures of 3a (a)
and 3b (b). All hydrogen atoms are omitted for clarity.
˚
Table 1. Selected Bond Distances (A) and Angles (deg.) of 3a
and 3b
ligand was isolated in good yield (Scheme 2). The iridium
center possessed an iodide anion as the halogen ligand. The
singlet resonance of Ccarbene at δ 205.2 in the 13C NMR
spectrum provided direct spectral evidence for the formation
of 3a. The lower field shift of the carbene carbon signal
compared to the unsaturated five-membered carbene carbon
resonances was ascribed to the strong electron-donating
character of the six-membered carbene ligand in 3a.6,11
Similar to other carbene transfer reactions using silver
carbene complexes, the silver complex of the perimidine
carbene acted as a carbene transfer reagent to the iridium
atom: the reaction of [IrCl(cod)]2 with excess perimidinium
salt 1a in the presence of Ag2O in toluene, followed by the
removal of the silver salt and purification by column chro-
matography, yielded yellow powders of 4a in good yield
(Scheme 2). In contrast to the use of LiN(SiMe3)2, FAB-MS
and elemental analysis confirmed the halogen ligand of 4a
was chloride. The difference in the halide ligand was prob-
ably due to the different solubility of LiI and AgI, which were
formed during the complexation reaction.
Iridium complexes with a more bulky perimidine carbene
ligand derived from 1b were synthesized in a similar manner
to 3a [LiN(SiMe3)2 as the base] and 4a (Ag2O method),
giving the iodo-Ir(carbene)(cod) complex 3b and its chloro
derivative 4b, respectively. In the 1H NMR spectra of 3b and
4b, the proton signal of the NCHMe2 group appeared at a
lower field (δ 6.63 for 3b; 6.93 for 4b) than that of 1b,
probably due to the proximity of the isopropyl group to
the electron-rich metal center.6
3a
Ir-I
2.6746(3)
2.162(4)
2.096(4)
1.366(6)
89.32(12)
123.9(3)
119.0(3)
Ir-C1
2.035(4)
2.213(4)
2.140(4)
1.353(5)
119.1(3)
117.6(3)
Ir-C19
Ir-C20
Ir-C23
C1-N1
C1-Ir-I
Ir-C1-N2
C1-N2-C18
Ir-C24
C1-N2
Ir-C1-N1
C1-N1-C12
3b
Ir-I
2.6845(2)
2.173(3)
2.117(3)
1.368(3)
87.57(7)
123.88(19)
116.0(2)
Ir-C1
2.038(3)
Ir-C21
Ir-C22
2.210(3)
2.129(3)
1.357(3)
119.02(19)
118.3(2)
Ir-C25
Ir-C26
C1-N1
C1-N2
C1-Ir-I
Ir-C1-N2
C1-N2-C18
Ir-C1-N1
C1-N1-C12
are listed in Table 1 (structures of 4a and 4b are given in the
Supporting Information). The coordination environments
around the iridium center of 3a and 3b are essentially the
same, and each iridium atom possesses a square-planar
geometry. The distances of Ir-Ccarbene for 3a and 3b are
˚
2.035(4) and 2.038(3) A, respectively, which are within the
range observed for (X)Ir(carbene)(cod) complexes.11b,d,e,g
The longer distances of Ir-C(19) and Ir-C(20) compared
to those of Ir-C(23) and Ir-C(24) for 3a reflect the strong
trans influence of the carbene ligand. The dihedral angles of
the perimidine ring and phenyl ring attached to the nitrogen
atom are 82.7° for 3a and 76.9° for 3b, and thus, the iridium
atom and the hydrogen atom of the phenyl ring do not
interact in these complexes.
The molecular structures of the iridium complexes 3a, 3b,
4a, and 4b were determined by X-ray crystallographic ana-
lyses. Figure 1 shows the molecular structures of iodide
complexes 3a and 3b, and their bond distances and angles
Ortho C-H Bond Activation: Preparation of a Cyclometa-
lated Ir Complex. We examined an ortho C-H bond activa-
tion of the phenyl ring attached to a nitrogen atom of the
perimidine ligand to prepare a cyclometalated complex. We
previously reported the ortho-metalation of imidazolium-
based carbene ligands by iridium, following the similar
reaction conditions for the synthesis of 3b and 4b.5 The
different reactivity toward the C-H bond activation for
the perimidine carbene ligands was ascribed to the stability
of complexes 3 and 4, and the toluene solutions of 3 and 4
were stable under refluxing conditions.
€
(11) (a) Hermann, W. A.; Elison, M.; Fisher, J.; Kocher, C.; Artus,
G. R. J. Chem.;Eur. J. 1996, 2, 772. (b) Vazquez-Serrano, L. D.; Owens,
B. T.; Buriak, J. M. Chem. Commun. 2002, 21, 2518. (c) Voutchkova, A. M.;
Appelhans, L. N.; Chianese, A. R.; Crabtree, R. H. J. Am. Chem. Soc. 2005,
127, 17624. (d) Prinz, M.; Veiros, L. F.; Calhorda, M. J.; Ramao, C. C.;
Herdtweck, E.; Kuehn, F. E.; Hermann, W. A. J. Organomet. Chem. 2006,
691, 4446. (e) Frey, G. D.; Rentzsch, C. F.; von Preysing, D.; Scherg, T.;
Muhlhofer, M.; Herdtweck, E.; Hermann, W. A. J. Organomet. Chem. 2006,
691, 5725. (f ) Kelly, R. A., III; Clavier, H.; Giudice, S.; Scott, N. M.; Stevens,
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Organometallics 2008, 27, 202. (g) Kownacki, I.; Kubicki, M.; Szubert, K.;
Marciniec, B. J. Organomet. Chem. 2008, 693, 321. (h) Tapu, D.; Dixon,
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We also prepared an iridium complex with an N-benzyl-
substituted perimidine ligand 2 to reduce the steric repulsion
between the nitrogen substituent and the iridium metal

Article
Organometallics, Vol. 29, No. 18, 2010 4123
ring,11 and we thus tried to prepare an acetate-Ir(carbene)
complex. When [IrCl(cod)]2, perimidinium salt, and silver
acetate were mixed in toluene, the product was a complicated
reaction mixture, and no single component was isolated. The
acetate-Ir(carbene) complex was successfully prepared by
treatment with [IrCl(cod)]2, perimidinium salt, LiN(SiMe3)2,
and excess silver acetate in THF at room temperature (eq 2).
The analytically pure compound 3c was obtained by recrys-
tallization from saturated hexane solution. The signal of the
carbonyl carbon was observed at δ 176.9 in the 13C NMR,
clearly indicating the presence of the acetate ligand. The
molecular structure and selected bond distances and angles
are listed in Figure 3 and Table S2, respectively. Similar to
the halide-Ir(carbene)(cod) complexes, the iridium atom
possesses a square-planar geometry and the acetate ligand
attaches to the iridium in an η1-coordination mode.
Figure 2. ORTEP drawing of the molecular structure of 5.
All hydrogen atoms are omitted for clarity.
Compared with the halide-Ir(carbene)(cod) complexes,
the acetate derivative 3c was unstable under toluene reflux-
ing conditions, but isolation and characterization of any
reaction product failed. Ortho C-H bond activation of the
phenyl group attached to the nitrogen atom of the perimidine
proceeded by treatment of complex 3c with 1a, LiN(SiMe3)2,
and a slight excess of silver acetate. The cyclometalated
product, (C∧C:)2Ir(OAc) (6), was isolated in quantitative
yield, where C∧C: is a cyclometalated perimidine carbene
ligand (eq 3).
Figure 3. ORTEP drawing of the molecular structure of 3c.
All hydrogen atoms are omitted for clarity.
During purification of the crude product 6 by silica gel
chromatography, a small amount of 6 was decomposed to
give a chloride-bridged dinuclear Ir complex, [(C∧C:)2Ir(μ-Cl)]2
(7). In the 1H NMR of 7, the resonance corresponding to the
acetate ligand disappeared and a new set of signals assignable to
the perimidine ligand was observed. The formation of 7 from
the acetate derivative 3c is probably due to the preferential
coordination of the halide ligand to the metal center over that of
the acetate ligand, which was also observed for Cp*MX2 (M =
Rh, Ir) complexes.11a,e A single crystal was grown from the
CH2Cl2/hexane solution, and the molecular structure of 7 was
clarified by X-ray crystallographic analysis. The molecular
structure and selected bond distances and angles are listed in
Figure 4 and Table S3, respectively.
center. The corresponding iridium complex 5 was prepared
in a similar manner to the synthesis of 3b and 4b (eq 1).
Crystallographic analysis to determine the molecular struc-
ture of 5 (Figure 2 and Table S1) revealed that the phenyl
moiety of the benzyl group was positioned far from the metal
center due to the flexibility of the benzyl methylene group.
The toluene solution of 5 was stable under refluxing condi-
tions, and no C-H bond activation was observed for 5.
Both of the iridium atoms have a distorted octahedral
geometry, and two cyclometalated perimidine carbene li-
gands coordinate to the metal center. Similar to the pre-
viously reported [(pypi)2Ir(μ-Cl)]2 (pypi = pyridyl[1,2-a]{2-
phenylimidazol}-3-ylidene) complex, the chloride atoms are
Several research groups recently reported that the carbox-
ylate group attached to the metal center is effective for the
intra- and intermolecular C-H activation of the aromatic

4124 Organometallics, Vol. 29, No. 18, 2010
Tsurugi et al.
with 3c and benzoic anhydride produced benzoate-Ir-
MeNPhNcarbene)(cod) (3d) in good yield via an exchange
(
reaction of the carboxylate group (eq 4). Carboxylate deri-
vatives 3c and 3d were reacted with phenylpyridine in
refluxing toluene to give 8c and 8d in good yield (eq 5).
1
The H NMR spectrum of 8 showed one set of the perimi-
dine-based carbene ligand, phenylpyridine, and carboxylate
groups, whereas the resonances corresponding to the cod
ligand were not observed. The X-ray analysis of 8d indicates
the formation of (C∧C:)(C∧N)Ir(OCOPh), where C∧N is a
cyclometalated phenylpyridine ligand (Figure 5; selected
bond distances and angles are listed in Table S4; structure
of 8c is given in the Supporting Information).
Figure 4. ORTEP drawing of the molecular structure of 7.
All hydrogen atoms are omitted for clarity.
1H NMR and GC-MS monitoring of the reaction se-
quence revealed the generation of 1,3-cod, but we did not
observe an intermediate for the formation of 8. To gain
further insight into the reaction mechanism, we perfomed
deuterium labeling experiments (Scheme 3). First, we pre-
pared a perimidinium salt (1a-d5) and an iridium complex
(3d-d5), where the C6D5 group was attached to the nitrogen
atom of the perimidine ring. Under the same conditions in
which 8d was formed, one deuterium atom was incorporated
into 1,3-cod (79% d0 þ 21% d1). 1,3-Cod (82% d0 þ 18% d1)
was also detected by the reaction of 3d with phenylpyridine-
d5, indicating that the deuterium atom of 1,3-cod was due to
the C6D5 group attached to the perimidine and pyridine
ring.
On the basis of the deuterium labeling experiments, we
propose the reaction pathway for the formation of 8 shown
in Scheme 4. Due to the thermal instability of the carboxylate
complexes 3c and 3d compared with the halide complexes 3a
and 3b, carboxylate-induced intramolecular C-H bond
activation may occur at the ortho position of the phenyl
group bound to pyridine or perimidine in the first step to give
9, via a sterically less hindered, acetate-chelated, six-mem-
bered transition state.8b As observed for the oxidative addi-
tion of the C-H bond of R,β-unsaturated imines to rhodium
compounds,12 oxidative addition of the C-H bond of the
other phenyl group affords intermediate 10. Due to the
Figure 5. ORTEP drawing of the molecular structure of 8d.
All hydrogen atoms are omitted for clarity.
positioned trans to the Caryl donor atoms, indicating a
stronger trans influence of Caryl than that of Ccarbene.5 The
distances of Ir-Ccarbene are similar to that in the monomeric
iridium complexes 3 and 4. The ortho position of the phenyl
ring attached to one of two nitrogen atoms of the perimidine
ring is metalated to form a five-membered metallacycle.
The distances of Ir-Caryl for Ir1-C13 and Ir1-C31 are
˚
1.992(13) and 2.019(12) A, respectively, which are within the
range typically observed for ortho-metalated iridium com-
plexes.3e,4,5,11a,11d,11e The planarity of the perimidine backbone
is slightly distorted due to the formation of the ortho-metalated
structure.
Preparation of a Perimidine-carbene- and Phenylpyridine-
Ligated Cyclometalated Ir Complex and the Mechanistic
Study. To clarify the reaction mechanism for the C-H bond
activation of the phenyl group of the perimidine carbene
ligand, we perfomed a controlled experiment: mixing 3c with
the perimidinium salt 1a and LiN(SiMe3)2 without silver
acetate afforded iodo-Ir(MeNPhNcarbene)(cod) (3a) in 60%
yield due to the strong affinity of the halide ligand to the
metal center. Thus, we examined the reaction of 3a with
aromatic substrates having carbonyl or pyridyl groups as
linkers to the central metal, instead of the perimidinium salt.
Although the reaction of 3c with methyl benzoate or phe-
nylpyridine did not proceed at room temperature, treatment
(12) (a) Colby, D. A.; Bergman, R. G.; Ellman, J. A. J. Am. Chem.
Soc. 2006, 128, 5604. (b) Colby, D. A.; Bergman, R. G.; Ellman, J. A. J. Am.
Chem. Soc. 2008, 130, 3645.

Article
Organometallics, Vol. 29, No. 18, 2010 4125
Scheme 3. Deuterium Labeling Experiment for the Formation
of 8d
Figure 6. ORTEP drawing of the molecular structure of 11.
All hydrogen atoms are omitted for clarity.
Scheme 4. Proposed Mechanism for the Formation of 8
˚
Table 2. Selected Bond Distances (A) and Angles (deg.) of 11
Ir-C1
2.057(4)
2.000(4)
2.162(3)
174.43(13)
96.34(14)
83.49(12)
175.60(12)
87.41(10)
126.5(4)
Ir-C19
2.069(4)
1.990(4)
2.164(3)
78.84(15)
99.36(13)
95.44(14)
88.38(12)
126.4(4)
128.6(4)
Ir-C13
Ir-C31
Ir-O1
Ir-O2
C1-Ir-C19
C1-Ir-C31
C1-Ir-O2
C13-Ir-O1
O1-Ir-O2
O2-C40-C39
C1-Ir-C13
C1-Ir-O1
C13-Ir-C32
C13-Ir-O2
O1-C38-C39
C38-C39-C40
carboxylic acid directly reacts with Ir-H species to form 8 and
dihydrogen in the final step. We presume that (C∧C:)2Ir(OAc)
(6) was obtained in same manner, and the excess AgOAc was an
acetate anion source for the reaction.
Preparation of (C∧C:)2Ir(acac) and the Photophysical
Properties. Homoleptic and heteroleptic cyclometalated
phenylpyridine complexes and phenylcarbene complexes of
Ir(III) are strong phosphorescent molecules.3f,i,j,4,13 We thus
attempted to prepare tris(C∧C:)Ir to study the photophysical
properties of perimidine-based carbene iridium complexes,
but the preparation of tris(C∧C:)Ir complexes failed under
the reaction conditions, in which 6 was formed in the
presence of excess perimidinium salt. However, an acetyl-
acetonato ligand was successfully introduced to 6, affording
(C∧C:)2Ir(acac) (11). The mixed-ligated complex 11 was
prepared in a successive manner from [IrCl(cod)]2 by the
in situ generation of 6, followed by the addition of acetyla-
cetone and Na2CO3 (eq 6). In the 1H NMR of 11, the olefinic
proton of the acetylacetonate ligand was observed at δ 5.01.
The olefinic proton of the acetylacetonate ligand and the
methyl protons attached to the perimidine ligand were
observed in 1:6 ratio, indicating that one acetylacetonate
and two perimidine ligands were bound to the iridium atom.
The molecular structure was clarified by X-ray analysis of
single crystals of 11 (Figure 6 and Table 2). The iridium
center has a distorted octahedral geometry, and acetylace-
tonate attaches to the iridium through a η2-(O,O) coordina-
detection of 1,3-cod from the reaction mixture, isomerization of
1,5-cyclooctadiene seems to proceed via migratory insertion of
Ir-H to cyclooctadiene and subsequent β-hydrogen elimina-
tion. Because hydrogen-accepted products by cyclooctadienes,
cyclooctene, or cyclooctane, were not detected in the 1H NMR
and GC-MS analyses, we assume that the in situ generated
(13) (a) Kim, J. I.; Shin, I.-S.; Kim, H.; Lee, J.-K. J. Am. Chem. Soc.
2005, 127, 1614. (b) Thomas, K. R. J.; Velusamy, M.; Lin, J. T.; Chien, C.-H.;
Tao, Y.-T.; Wen, Y. S.; Hu, Y.-H.; Chou, P.-T. Inorg. Chem. 2005, 44, 5677.
(c) Huang, Y.-T.; Chuang, T.-H.; Shu, Y.-L.; Kuo, Y.-C.; Wu, P.-L.; Yang,
C.-H.; Sun, I.-W. Organometallics 2005, 24, 6230. (d) Zhen, H.; Jiang, C.;
Yang, W.; Jiang, J.; Huang, F.; Cao, Y. Chem.;Eur. J. 2005, 11, 5007. (e)
Zhao, A.; Jiang, C.-Y.; Shi, M.; Li, F.-Y.; Yi, T.; Cao, Y.; Huang, C.-H.
Organometallics 2006, 25, 3631. (f ) Zhang, X.; Gao, J.; Yang, C.; Zhu, L.;
Li, Z.; Zhang, K.; Qin, J.; You, Y.; Ma, D. J. Organomet. Chem. 2006, 691,
4312. (g) Yang, C.-H.; Chen, C.-H.; Sun, I.-W. Polyhedron 2006, 25, 2407.
(h) Li, W.; Chen, Z.; Zhao, Q.; Shen, L.; Li, F.; Yi, T.; Cao, Y.; Huang, C.
Inorg. Chem. 2007, 46, 5518. (i) Chen, H.; Zhao, Q.; Wu, Y.; Li, F.; Yang, H.;
Yi, T.; Huang, C. Inorg. Chem. 2007, 46, 11075. ( j) Shin, I.-S.; Kim, J. I.;
Kwon, T.-H.; Hong, J.-I.; Lee, J.-K.; Kim, H. J. Phys. Chem. C 2007, 111,
2280. (k) Velusamy, M.; Thomas, K. R. J.; Chen, C.-H.; Lin, J. T.; Wen, Y. S.;
Hsieh, W.-T.; Lai, C.-H.; Chou, P.-T. Dalton Trans. 2007, 3025. (l) Coughlin,
F. J.; Westrol, M. S.; Oyler, K. D.; Byme, N.; Kraml, C.; Zysman-Colman, E.;
Lowry, M. S.; Bernhard, S. Inorg. Chem. 2008, 47, 2039. (m) Bronstein,
H. A.; Finlayson, C. E.; Kirov, K. R.; Friend, R. H.; Williams, C. K.
Organometallics 2008, 27, 2980. (n) Agarwal, N.; Nayak, P. K. Tetrahedron
Lett. 2008, 49, 2710.
˚
tion mode. The distances of Ir-O1 (2.162(4) A) and Ir-O2
(2.162(4) A) are within the range observed for other Ir(acac)
˚
complexes.3f,4,13b,13c,13e,13g,13k The coordination geometry of

4126 Organometallics, Vol. 29, No. 18, 2010
Tsurugi et al.
carboxylate group bound to the iridium atom, and subse-
quent oxidative addition of the other C-H bonds of the
phenyl group was key to producing complex 8. The acac-
ligated complex 11 exhibited phosphorescent emission at
λmax = 555 nm (τ = 0.65 μs, ΦPL = 0.0018) in CH2Cl2
solution at room temperature.
Experimental Section
General Procedures. All manipulations involving air- and
moisture-sensitive organometallic compounds were operated
using the standard Schlenk techniques under argon.
Perimidine,15 [IrCl(cod)]2,16 and phenylpyridine-d5 were pre-
17
Figure 7. Absorption and emission spectra (excited at 350 nm)
of 11. Both spectra were measured in CH2Cl2 at room temper-
ature.
pared according to the literature. Other chemicals were purchased
and used without further purification. Hexane, THF, toluene, and
ether were dried and deoxygenated by distillation over sodium
benzophenone ketyl under argon. Benzene-d6, toluene-d8, CDCl3,
the perimidine ligand to iridium is similar to the chloro-
bridged dimer 7.
1
CD2Cl2, and DMSO-d6 were degassed and stored under Ar. H
NMR (300 MHz, 400 MHz) and 13C NMR (75 MHz, 100 MHz)
spectra were measured on Varian Unity Inova-300 and Bruker
Avance III-400 spectrometers. Assignments for 1H and 13C NMR
peaks for some of the complexes were aided by 2D 1H-1H COSY,
2D 1H-1H NOESY, 2D 1H-13C HETCOR, and/or 2D 1H-13C
HMBC spectra. The elemental analyses were recorded by using a
Perkin-Elmer 2400 at the Faculty of Engineering Science, Osaka
University. GC-MS measurement was carried out using a DB-1
capillary column (0.25 mm ꢀ 30 m) on a Shimadzu GCMS-
QP2010Plus. All melting points were measured in sealed tubes
under an argon atmosphere. Steady-state absorption spectra
were measured using a UV-vis spectrophotometer (Hitachi,
U-3500). Steady-state emission and excitation spectra were
measured with a spectrofluorometer (Hitachi, F850E). The
emission lifetime of the iridium complexes was measured using
a time-correlated single photon counting (TCSPC) method.
The experimental setup for TCSPC measurement was described
previously.18
The absorption and emission spectra for 11 were measured
in CH2Cl2 at room temperature (Figure 7). The absorption
spectrum shows an intense band at λmax = 234 nm (ε ≈ 5.8 ꢀ
104 M-1 cm-1) assignable to the π-π* transition of the
cyclometalated perimidine ligand and a weaker band at around
300-450 nm (λmax = 349 nm, ε ≈ 2.6 ꢀ 104 M-1 cm-1), which
is assigned to MLCT transition. Both absorptions are typically
observed for cyclometalated Ir(III) complexes.3 The complex
11 was luminescent at room temperature with emission char-
acteristics of phosphorescence at λmax = 555 nm (τ =0.65 μs)14
in CH2Cl2 solution. The excitation spectrum of 11 matches the
absorption spectrum with a maximum efficiency at π-π*
and MLCT transition bands (Figure S4 in Supporting In-
formation). The nonradiative decay rates are comparable to
those of the other cyclometalated Ir(III) complexes, although
the radiative decay rate is lower (kr = 2.8 ꢀ 103 s-1, knr = 1.5 ꢀ
Synthesis of N-Phenylperimidine. Perimidine (3.364 g, 20.0
mmol), Cs2CO3 (6.519 g, 20.0 mmol), and CuCl (0.595 g, 6.01
mmol) were placed in a Schlenk, and a mixture of acetylacetone
(1.512 g, 15.1 mmol) and bromobenzene (4.102 g, 26.2 mmol) in
NMP (40 mL) was added. The reaction mixture was degassed
and heated at 130 °C for 18 h under an argon atmosphere. The
suspension was cooled to ambient temperature, and saturated
NaHCO3(aq) (800 mL) was added. The mixture was filtered,
and the filtrate was washed with saturated NaHCO3(aq) (800
mL). The organic product was extracted with methylene chlo-
ride, and the solvent was evaporated. Purification by flash
column chromatography on silica gel using CH2Cl2-MeOH
as the eluent (v/v = 40:1) gave a brown solid of N-phenylper-
imidine in 58% yield (2.826 g, 11.6 mmol), mp 96 °C. 1H NMR
(CDCl3, 300 MHz, 35 °C): δ 5.90 (d, J = 7.4 Hz, 1H), 6.87 (d,
J = 7.1 Hz, 1H), 6.96 (t, J = 8.0 Hz, 1H), 7.09 (d, J = 8.2 Hz,
1H), 7.15-7.30 (m, 3H), 7.35-7.65 (m, 5H). 13C NMR (CDCl3,
75.5 MHz, 35 °C): δ 102.5, 115.5, 119.8, 121.0, 122.7, 127.1,
127.5, 128.8, 129.1, 130.7, 135.5, 139.2, 139.3, 142.9, 147.4. IR
(NaCl film, cm-1): ν~ 3053, 1629, 1580, 1493, 1395, 1370, 1321,
1278, 1217, 1200, 1165, 823, 767, 698. HRMS (EI): m/z calcd for
C17H12N2 244.1001; found 244.1016.
106 s-1).14 Therefore, the quantum efficiency of 11 (ΦPL
=
0.0018) is very low compared to the phenylpyridine- and
phenylcarbene-based Ir complexes.
Conclusion
In summary, we successfully prepared iridium(I) com-
plexes with N,N0-disubstituted perimidine carbene ligands.
In contrast to other five-membered carbene analogues, the
use of carboxylate ligands is necessary for the perimidine-
carbene-directed C-H bond activation reaction. Investiga-
tion of the formation of (C∧C:)(C∧N)Ir(OCOR) (8) revealed
the dissociation of 1,3-cyclooctadiene from the iridium
center during the C-H bond activation reaction. On the
basis of the deuterium labeling experiments for the forma-
tion of 8, a C-H bond of the phenyl group bound to the
perimidine carbene or pyridine ligand was activated by the
Synthesis of N-Methyl-N-phenylperimidinium Iodide ([MeNPhN
-
carbene-H][I], 1a). Methyl iodide (42 mL, 7.0 ꢀ 102 mmol) was
added to a Schlenk containing N-phenylperimidine (1.671 g, 6.84
(15) Herbert, J. M.; Woodgate, P. D.; Denny, W. A. J. Med. Chem.
1987, 30, 2081.
(16) Herde, J. H.; Lambert, J. C.; Senoff, C. V. Inorg. Synth. 1974,
15, 18.
(17) Kozhushkov, S. I.; Yufit, D. S.; Ackermann, L. Org. Lett. 2008,
10, 3409.
(18) Nagasawa, Y.; Itoh, T.; Yasuda, M.; Ishibashi, Y.; Ito, S.;
(14) See Supporting Information.
Miyasaka, H. J. Phys. Chem. B 2008, 112, 15758.

Article
Organometallics, Vol. 29, No. 18, 2010 4127
mmol). The Schlenk was covered with Al foil, and the mixture was
stirred for 67 h at room temperature. After removal of excess methyl
iodide, the resulting orange solid was washed with ether (50 mL ꢀ 5)
and dried in vacuo to give 1a in 91% yield (2.413 g, 6.25 mmol), mp
255 °C. 1H NMR (CDCl3, 300 MHz, 35 °C): δ 3.77 (s, 3H, CH3),
6.34 (d, J = 7.7 Hz, 1H), 6.85 (d, J = 7.5 Hz, 1H), 7.21-7.27 (m,
1H), 7.40-7.55 (m, 3H), 7.58-7.70 (m, 3H), 7.81-7.87 (m, 2H),
9.58 (s, 1H, NCHN). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ 39.9,
108.0, 109.3, 121.2, 124.4, 124.9, 127.5, 128.0, 128.4, 131.0, 131.3,
133.0, 134.3, 134.9, 135.4, 151.7. IR (KBr tablet, cm-1): ν~ 3061,
3035, 3009, 2948, 1660, 1605, 1587, 1491, 1421, 1379, 817, 760, 693.
HRMS (FAB) for [MeNPhNcarbene-H]þ: m/z calcd for C18H15N2
259.1235; found 259.1202.
gel using CH2Cl2 as the eluent to give a yellow powder of 3a in
1
74% yield (97.0 mg, 1.4 ꢀ 10-1 mmol), mp 265 °C (dec). H
NMR (CDCl3, 300 MHz, 35 °C): δ 0.79-0.95 (m, 1H, CH2 of
cod), 1.10-1.49 (m, 4H, CH2 of cod), 1.69-1.94 (m, 2H, CH2 of
cod), 2.14-2.29 (m, 1H, CH2 of cod), 2.50-2.59 (m, 1H, dCH
of cod), 3.31-3.37 (m, 1H, dCH of cod), 4.16 (s, 3H, CH3),
4.45-4.64 (m, 2H, dCH of cod), 5.98 (d, J = 8.1 Hz, 1H, Ar),
6.72 (m, 1H, Ar), 7.12 (t, J = 7.8 Hz, 1H, Ar), 7.29 (d, J = 8.1
Hz, 1H, Ar), 7.33-7.41 (m, 3H, Ar), 7.48-7.62 (m, 3H, Ar),
8.15-8.20 (m, 1H, Ar). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ
26.5 (CH2 of cod), 27.9 (CH2 of cod), 32.2 (CH2 of cod), 36.4
(CH2 of cod), 43.6 (NCH3), 54.8 (dCH of cod), 56.2 (dCH of
cod), 80.8 (dCH of cod), 84.0 (dCH of cod), 104.7 (N-Ph),
106.7 (CH, perimidine ring), 119.4, 120.7 (CH, permidine ring),
121.3 (CH, N-Ph), 127.5 (CH, perimidine ring), 127.9 (CH),
128.2 (CH), 128.5 (CH, N-Ph), 128.7 (CH, N-Ph), 129.6 (CH,
perimidine ring), 134.3, 134.7 (CH, perimidine ring), 136.1,
137.7, 139.1, 205.2 (IrdC). IR (KBr tablet, cm-1): ν~ 3058,
3041, 3008, 2955, 2935, 2906, 2873, 2826, 1633, 1583, 1492, 1426,
1378, 1399, 1120, 1083, 1074, 814, 767, 759, 696. MS (FAB): m/z
686 (Mþ). Anal. Calcd for C26H26IIrN2: C, 45.55; H, 3.82; N,
4.09. Found: C, 45.43; H, 3.47; N, 4.05.
Synthesis of N-Isopropyl-N-phenylperimidinium Iodide ([iPrNPhN
-
carbene-H][I], 1b). Isopropyl iodide (6.847 g, 40.3 mmol) was
added to a Schlenk containing N-phenylperimidine (0.726 g,
2.97 mmol). The Schlenk was covered with Al foil, and the mixture
was refluxed for 48 h. After removal of excess isopropyl iodide, the
resulting yellow solid was purified by flash chromatography on
silica gel using CH2Cl2-MeOH as the eluent (v/v = 20:1) to give a
yellow powder of 1b in 65% yield (0.800 g, 1.93 mmol), mp 247 °C.
1H NMR (CDCl3, 300 MHz, 35 °C): δ 1.78 (d, J = 6.5 Hz, 6H,
CH(CH3)2), 4.75, (sept, J = 6.5 Hz, 1H, CH(CH3)2), 6.25 (d, J =
7.7 Hz, 1H), 7.11 (d, J = 7.4 Hz, 1H), 7.21 (t, J = 8.4 Hz, 1H),
7.41-7.53 (m, 3H), 7.54-7.66 (m, 3H), 7.84-7.90 (m, 2H), 8.69 (s,
1H, NCHN). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ 19.9, 54.8,
108.9, 109.1, 121.4, 124.2, 124.5, 127.5, 127.6, 128.1, 130.7, 131.0,
131.3, 133.9, 134.8, 135.5, 148.7. IR (NaCl film, cm-1): ν~ 3033,
3009, 2979, 1655, 1604, 1586, 1493, 1466, 1427, 1387, 1377, 1343,
1271, 820, 768, 731, 697. HRMS (FAB) for [iPrNPhNcarbene-H]þ:
m/z calcd for C20H19N2 287.1548, found 287.1548.
Iodo-Ir(iPrNPhNcarbene)(cod) (3b) was prepared in a similar
manner to 3a. Yield: 60%, mp 242 °C (dec). 1H NMR (CDCl3,
300 MHz, 35 °C): δ 0.68-0.82 (m, 1H, CH2 of cod), 0.97-1.25
(m, 3H, CH2 of cod), 1.34-1.47 (m, 1H, CH2 of cod), 1.57-1.86
(m, 2H, CH2 of cod), 1.75 (d, J = 6.9 Hz, 3H, CHMe2), 1.79 (d,
J = 6.9 Hz, 3H, CHMe2), 2.04-2.20 (m, 1H, CH2 of cod),
2.50-2.60 (m, 1H, dCH of cod), 3.39-3.46 (m, 1H, dCH of
cod), 4.27-4.37 (m, 1H, dCH of cod), 4.49-4.57 (m, 1H, dCH
of cod), 5.76 (d, J = 8.1 Hz, 1H, Ar), 6.56 (sep, J = 6.9 Hz, 1H,
CHMe2), 6.91-7.02 (m, 2H, Ar), 7.15 (d, J = 8.4 Hz, 1H, Ar),
7.20-7.29 (m, 3H, Ar), 7.38-7.52 (m, 3H, Ar), 8.14 (d, J = 7.1
Hz, 1H, Ar). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ 18.1, 21.3,
26.3, 28.0, 31.9, 36.5, 55.5, 55.6, 60.7, 79.1, 83.2, 106.5, 108.0,
120.71, 120.73, 120.9, 127.2 (2C), 128.25, 128.32, 128.6, 129.3,
133.4, 134.8, 135.4, 137.3, 138.9, 205.1 (IrdC). IR (NaCl film,
cm-1): ν~ 3060, 2933, 2909, 2877, 2830, 1633, 1580, 1491, 1424,
1375, 1335, 1323, 1265, 1229, 1159, 816, 768, 736, 699. MS
(FAB): m/z 714 (Mþ). Anal. Calcd for C28H30IIrN2: C, 47.12; H,
4.24; N, 3.93. Found: C, 46.89; H, 4.03; N, 3.88.
Synthesis of N-Methylperimidine. To an ethanol solution (36
mL) containing KOH (0.794 g, 12.0 mmol) was added perimi-
dine (1.688 g, 10.0 mmol), and the reaction mixture was stirred
for 1 h at room temperature. Methyl iodide (0.75 mL, 12.0
mmol) was added, and the mixture was refluxed for 3 h. After
removal of the solvent and methyl iodide, the organic compound
was extracted with CH2Cl2. All the solvent was evaporated to
give a brown powder of N-methylperimidine in 61% yield (1.120
g, 6.15 mmol), mp 118 °C. 1H NMR (CDCl3, 300 MHz, 35 °C): δ
3.12 (s, 3H, NCH3), 6.05-6.14 (m, 1H), 6.83 (d, J = 7.0 Hz, 1H),
7.10-7.28 (m, 5H). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ 35.7,
100.1, 114.7, 119.2, 120.0, 122.5, 127.1, 128.4, 135.0, 138.2,
143.2, 148.2. IR (NaCl film, cm-1): ν~ 3093, 3049, 3007, 2958,
2919, 2855, 2818, 1628, 1588, 1334, 1256, 1152, 1083, 822, 768.
HRMS (EI): m/z calcd for C12H10N2 182.0845, found 182.0844.
Synthesis of Chloro-Ir(MeNPhNcarbene)(cod) (4a). Toluene (3 mL)
was added to a Schlenk containing Ag2O (47.0 mg, 2.0 ꢀ 10-1
mmol), [IrCl(cod)]2 (35.0 mg, 5.2 ꢀ 10-2 mmol), and 1a (77.0 mg,
2.0 ꢀ 10-1 mmol) at room temperature. The reaction mixture was
stirred for 1 h at room temperature and then refluxed for 24 h. After
evaporation of all the solvent, the iridium compound was extracted
with CH2Cl2 and purified by flash chromatography on silica gel
using CH2Cl2-MeOH as the eluent (v/v = 80:1) to give a yellow
powder of 4a in 91% yield (56.0 mg, 9.5 ꢀ 10-2 mmol), mp >270 °C.
1H NMR (CDCl3, 300 MHz, 35 °C): δ 0.93-1.09 (m, 1H, CH2 of
cod), 1.16-1.46 (m, 3H, CH2 of cod), 1.59-1.85 (m, 2H, CH2
of cod), 1.88-2.02 (m, 1H, CH2 of cod), 2.23-2.35 (m, 1H, CH2 of
cod), 2.35-2.48 (m, 1H, dCH of cod), 3.17-3.24 (m, 1H, dCH
of cod), 4.21-4.31 (m, 1H, dCH of cod), 4.28 (s, 3H, CH3),
4.39-4.47 (m, 1H, dCH of cod), 6.06 (d, J = 7.5 Hz, 1H, Ar),
6.67-6.75 (m, 1H, Ar), 7.12 (t, J=7.8Hz, 1H, Ar), 7.29(d,J=8.4
Hz, 1H, Ar), 7.33-7.40 (m, 3H, Ar), 7.50-7.68 (m, 3H, Ar),
8.08-8.13 (m, 1H, Ar). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ
26.5 (CH2 of cod), 29.4 (CH2 of cod), 30.6 (CH2 of cod), 36.1 (CH2
of cod), 42.9 (NCH3), 51.0 (dCH of cod), 54.3 (dCH of cod), 82.2
(dCH of cod), 85.6 (dCH of cod), 104.8 (CH, N-Ph), 106.8 (CH,
permidine ring), 119.5, 120.8 (CH, perimidine ring), 121.3 (CH,
N-Ph), 127.5 (CH, permidine ring), 127.7 (CH, N-Ph), 127.9 (CH,
N-Ph), 128.5 (CH), 128.6 (CH), 129.9 (CH, permidine ring), 134.2
(CH, permidine ring), 134.3, 136.0, 137.5, 139.7, 204.7 (IrdC). IR
(KBr tablet, cm-1): ν~ 3060, 3041, 3011, 3000, 2952, 2934, 2909,
2874, 2828, 1634, 1583, 1491, 1428, 1378, 1350, 1340, 1121, 1082, 813,
764, 695. MS (ESI): m/z594 (Mþ).Anal.CalcdforC26H26ClIrN2:C,
52.56; H, 4.41; N, 4.71. Found: C, 52.94; H, 4.08; N, 4.68.
Synthesis of N-Benzyl-N-methylperimidinium Chloride ([MeNBnN
-
carbene-H][Cl], 2). Benzyl chloride (11.0 mmol) was added to a
Schlenk containing N-methylperimidine (1.149 g, 6.31 mmol). The
reaction mixture was refluxed for 22 h. After cooling to room
temperature, hexane (40 mL) was added and a yellow-brown
precipitate was filtered and washed with hexane (40 mL ꢀ 2) and
ether (40 mL ꢀ 3). The solid was dried in vacuo to give a yellow-
brown powder of 2 in 99% yield (1.927 g, 6.24 mmol), mp 232 °C.
1H NMR (CDCl3, 300 MHz, 35 °C): δ 3.90 (s, 3H, CH3), 5.51 (s,
2H, CH2), 6.78 (d, J = 7.6 Hz, 1H), 6.82 (d, J = 7.6 Hz, 1H),
7.26-7.56 (m, 9H), 11.5 (s, 1H, NCHN). 13C NMR (DMSO-d6,75.5
MHz, 35 °C): δ 54.1, 55.1, 108.0, 108.7, 120.9, 123.5, 123.8, 127.6,
128.1, 128.4, 128.4, 128.9, 131.6, 132.8, 133.1, 134.1, 154.1. IR (KBr
tablet, cm-1): ν~ 3030, 2933, 2900, 2820, 1990, 1664, 1604, 1589,
1497, 1466, 1454, 1427, 1377, 1347, 1257, 1231, 1163, 1137, 1081,
1052, 978, 818, 767, 711, 642. HRMS (FAB) for [MeNBnNcarbene-
H]þ: m/z calcd for C19H17N2 273.1392, found 273.1402.
Synthesis of Iodo-Ir(MeNPhNcarbene)(cod) (3a). THF (5.5 mL)
was added to a Schlenk containing LiN(SiMe3)2 (32.0 mg, 1.9 ꢀ
10-1 mmol), [IrCl(cod)]2 (64.0 mg, 9.5 ꢀ 10-2 mmol), and 1a
(73.0 mg, 1.9 ꢀ 10-1 mmol) at room temperature. The reaction
mixture was stirred for 6 h at room temperature, and the solvent
was evaporated. The iridium compound was extracted with
CH2Cl2 and then purified by flash chromatography on silica

4128 Organometallics, Vol. 29, No. 18, 2010
Tsurugi et al.
Chloro-Ir(iPrNPhNcarbene)(cod) (4b) was prepared in a similar
manner to 4a. Yield: 80%, mp 250 °C (dec). 1H NMR (CDCl3,
300 MHz, 35 °C): δ 0.84-1.03 (m, 1H, CH2 of cod), 1.08-1.42
(m, 3H, CH2 of cod), 1.55-1.69 (m, 1H, CH2 of cod), 1.77-1.99
(m, 2H, CH2 of cod), 1.79 (d, J = 7.1 Hz, 3H, CHMe2), 1.88 (d,
J = 7.1 Hz, 3H, CHMe2), 2.18-2.33 (m, 1H, CH2 of cod),
2.42-2.51 (m, 1H, dCH of cod), 3.29-3.36 (m, 1H, dCH of
cod), 4.13-4.22 (m, 1H, dCH of cod), 4.37-4.45 (m, 1H, dCH
of cod), 5.94 (d, J = 8.0 Hz, 1H, Ar), 6.93 (sep, J = 7.1 Hz, 1H,
CHMe2), 6.98-7.09 (m, 2H, Ar), 7.22 (d, J = 8.1 Hz, 1H, Ar),
7.27-7.37 (m, 3H, Ar), 7.48-7.65 (m, 3H, Ar), 8.10-8.15 (m,
1H, Ar). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ 17.7, 21.0, 26.1,
29.4, 30.3, 36.4, 51.7, 53.3, 61.5, 80.3, 84.7, 106.5, 107.9, 120.7,
120.8, 120.9, 127.1, 127.2, 127.8, 128.35, 128.42, 129.6, 133.3,
134.6, 134.9, 137.0, 139.4, 204.4 (IrdC). IR (NaCl film, cm-1):
ν~ 3060, 2970, 2935, 2909, 2877, 2830, 1633, 1581, 1492, 1423,
1375, 1339, 1327, 1230, 1160, 817, 768, 735, 698. MS (FAB): m/z
622 (Mþ). Anal. Calcd for C28H30ClIrN2: C, 54.05; H, 4.86; N,
4.50. Found: C, 54.26; H, 4.63; N, 4.57.
124.3, 127.26, 127.30, 132.6, 134.6, 134.9, 138.6, 151.7, 184.9
(CdO), 207.8 (IrdC). IR (NaCl film, cm-1): ν~ 3051, 2963,
2925, 2850, 1681, 1633, 1585, 1571, 1526, 1480, 1455, 1419, 1383,
1349, 1320, 1264, 1223, 1108, 1078, 817, 744, 673. MS (FAB): m/z
707 ([M - OAc]þ).
Characterization of [(C∧C:)2Ir(μ-Cl)]2 (7). Mp > 270 °C. 1H
NMR (CDCl3, 300 MHz, 35 °C): δ 3.69 (s, 12H, CH3), 5.69 (d,
J = 7.8 Hz, 4H, Ar), 6.37 (t, J = 7.5 Hz, 4H, Ar), 6.49 (dd, J = 1.2
and 7.2 Hz, 4H, Ar), 6.61 (t, J = 6.9 Hz, 4H, Ar), 7.05 (t, J = 7.8
Hz, 4H, Ar), 7.39-7.61 (m, 20H, Ar). 13C NMR (CDCl3, 75.5
MHz, 35 °C): δ 42.6 (NCH3), 106.1, 109.8, 110.9, 120.6, 120.9,
121.1, 121.3, 123.5, 127.2, 127.4, 128.4, 132.6, 134.1, 134.2, 138.1,
151.7, 209.9 (IrdC). IR (KBr tablet, cm-1): ν~ 3053, 2955, 2925,
1632, 1586, 1570, 1525, 1479, 1455, 1442, 1420, 1381, 1350, 1315,
1265, 1216, 1107, 1075, 1031, 816, 768, 743. MS (FAB): m/z 707
([M - Cl]þ).
Synthesis of Benzoate-Ir(MeNPhNcarbene)(cod) (3d). THF (30 mL)
was added to a Schlenk containing 3c (0.57 g, 9.2 ꢀ 10-1 mmol) and
benzoic anhydride (0.21 g, 9.22 ꢀ 10-1 mmol) at room temper-
ature. The reaction mixture was stirred for 24 h at room temper-
ature, and the solvent was evaporated. The solid was washed with
ether (15 mL ꢀ 2) and hexane (15 mL) to give a yellow powder of
3d in 90% yield (0.59 g, 8.5 ꢀ 10-1 mmol), mp 218 °C (dec). 1H
NMR (C6D6, 400 MHz, 35 °C): δ 1.11-1.15 (m, 1H, CH2 of cod),
1.22-1.30 (m, 1H, CH2 of cod), 1.53-1.58 (m, 2H, CH2 of cod)
1.61-1.67 (m, 1H, CH2 of cod), 1.91-2.01 (m, 2H, CH2 of cod),
2.35-2.42 (m, 2H, CH2 and dCH of cod), 2.92-2.96 (m,
1H, dCH of cod), 4.11 (s, 3H, NCH3), 4.52-4.57 (m, 2H, dCH
of cod), 5.93 (d, J = 7.4 Hz, 1H, Ar), 6.24 (d, J = 7.4 Hz, 1H, Ar),
6.75 (t, J = 7.8 Hz, 1H, Ar), 6.99-7.09 (m, 4H, Ar), 7.13-7.21 (m,
6H, Ar), 7.95-7.97 (m, 1H, Ar), 8.44-8.47 (m, 2H, Ar). 13C NMR
(C6D6, 100 MHz, 35 °C): δ 27.2 (CH2 of cod), 30.4 (CH2 of cod),
30.8 (CH2 of cod), 36.7(CH2 of cod), 43.7(NCH3), 49.0 (dCH of
cod), 54.2 (dCH of cod), 82.2 (dCH of cod), 86.6 (dCH of cod),
105.3 (CH), 107.0 (CH), 120.3, 120.8 (CH), 121.2 (CH), 127.7
(CH), 127.9 (CH), 128.9 (CH), 129.2 (CH), 130.8 (CH), 130.8
(CH), 131.0 (CH), 132.3 (CH), 135.3, 137.0, 137.2, 138.4, 141.1,
172.0 (OCOPh), 206.8 (IrdC). IR (KBr tablet, cm-1): ν~ 3447,
3060, 2960, 2912, 2879, 2831, 1635, 1583, 1492, 1426, 1380, 1338,
1121, 1081, 815, 763, 713.
Chloro-Ir(MeNBnNcarbene)(cod) (5) was prepared in a similar
manner to 4a. Yield: 55% , mp 255 °C (dec). 1H NMR (CDCl3,
300 MHz, 35 °C): δ 1.25-1.49 (m, 1H, CH2 of cod), 1.64-1.86
(m, 4H, CH2 of cod), 2.08-2.38 (m, 3H, CH2 of cod), 2.90-2.99
(m, 1H, dCH of cod), 3.13-3.22 (m, 1H, dCH of cod), 4.38 (s,
3H, CH3), 4.59-4.71 (m, 2H, dCH of cod), 6.46 (d, J = 7.5 Hz,
1H, Ar), 6.72 (dd, J = 2.4 and 6.0 Hz, 1H, Ar), 7.13 (t, J = 8.1
Hz, 1H, Ar), 7.18-7.41 (m, 8H, Ar and CH2 of Bn). 13C NMR
(CDCl3, 75.5 MHz, 35 °C): δ 28.6 (CH2 of cod), 29.7 (CH2 of
cod), 32.3 (CH2 of cod), 33.8 (CH2 of cod), 42.8 (NCH3), 54.0,
54.9, 59.2, 84.0, 84.8, 104.6, 107.3, 119.9, 120.7, 121.2, 126.3,
127.1, 127.6, 128.6, 134.3, 134.4, 135.3, 135.6, 205.4 (IrdC). IR
(NaCl film, cm-1): ν~ 3062, 3029, 2958, 2913, 2879, 2831, 1634,
1585, 1429, 1384, 1338, 815, 764, 731. MS (EI): m/z 608 (Mþ).
Anal. Calcd for C27H28ClIrN2(CH2Cl2)0.33: C, 51.58; H, 4.54;
N, 4.40. Found: C, 51.52; H, 4.17; N, 4.46.
Synthesis of Acetate-Ir(MeNPhNcarbene)(cod) (3c). THF (30 mL)
was added to a Schlenk containing LiN(SiMe3)2 (0.167 g,
1.0 mmol), [IrCl(cod)]2 (0.336 g, 5.0 ꢀ 10-1 mmol), 1a (0.389 g,
1.0 mmol), and AgOAc (1.669 g, 10 mmol) at room temperature.
The reaction mixture was stirred for 6 h at room temperature, and
the solvent was evaporated. The iridium compound was extracted
with CH2Cl2, and the extract was concentrated. The resulting solid
was washed with hexane (30 mL ꢀ 2) to give a yellow powder of 3c
Synthesis of (C∧C:)(C∧N)Ir(OAc) (8c). Toluene (30 mL) was
added to a Schlenk containing 3d (0.174 g, 2.8 ꢀ 10-1 mmol) and
2-phenylpyridine (0.043 g, 7.5 ꢀ 10-1 mmol) at room temper-
ature. The reaction mixture was heated at 120 °C for 24 h under
an argon atmosphere. The mixture was cooled to ambient
temperature, and the solvent was evaporated. The resulting
solid was washed with hexane (15 mL) and ether (15 mL) to
give a yellow powder of 8c in 96% yield (0.178 g, 2.7 ꢀ 10-1
mmol), mp >270 °C (dec). 1H NMR (C6D6, 400 MHz, 35 °C): δ
1.87 (s, 3H, CH3COO), 3.90 (s, 3H, NCH3), 6.22 (d, J = 7.2 Hz,
1H, perimidine ring), 6.42 (d, J = 7.1 Hz, 1H, N-Ph), 6.58 (t, J =
6.2 Hz, 1H, py), 6.59 (t, J = 7.3 Hz, 1H, N-Ph), 6.72 (t, J = 6.2
Hz, 1H, N-Ph), 6.74 (t, J = 6.6 Hz, 1H, py-Ph), 6.86 (t, J = 7.4
Hz, 1H, py), 6.96-7.00 (m, 4H, 3H for perimidine ring; 1H for
py-Ph), 7.01 (t, J = 6.7 Hz, 1H, perimidine ring), 7.11 (t, J = 5.8
Hz, 1H, py-Ph), 7.34 (d, J = 6.6 Hz, 1H, py), 7.41 (d, J = 7.9 Hz,
1H, perimidine ring), 7.46 (d, J = 6.6 Hz, 1H, Ph-py), 7.61 (d,
J = 7.9 Hz, 1H, N-Ph), 8.82 (d, J = 5.5 Hz, 1H, py). 13C NMR
(C6D6, 100 MHz, 35 °C): δ 23.3 (OCH3), 42.9 (NCH3), 106.7
(CH, perimidine ring), 110.6, 112.6, 118.9 (py), 121.2 (CH,
perimidine ring), 121.6 (py), 122.0, 122.2, 122.3, 123.9, 124.9,
125.2, 127.6, 127.7, 129.7, 129.9, 130.4, 133.6, 133.8, 135.2,
135.5, 135.8, 137.1 (py), 138.0 (N-Ph), 138.7 (N-Ph), 147.6
(py), 150.0 (N-Ph), 166.0 (py), 191.2 (IrdC); some carbon
resonances are overlapped with C6D6 signals.
1
in 80% yield (0.496 g, 8.0 ꢀ 10-1 mmol), mp 185 °C (dec). H
NMR (CDCl3, 300 MHz, 35 °C): δ 1.03-1.59 (m, 5H, CH2 of
cod), 1.83-2.04 (m, 2H, CH2 of cod), 1.98 (s, 3H, CH3COO),
2.27-2.43 (m, 2H, CH2 and dCH of cod), 2.87-2.96 (m, 1H,
dCH of cod), 4.08-4.17 (m, 2H, dCH of cod), 4.29 (s, 3H,
NCH3), 6.01 (d, J = 7.5 Hz, 1H, Ar), 6.69 (dd, J = 1.8 and 6.9 Hz,
1H), 7.08 (t, J = 8.1 Hz, 1H, Ar), 7.22-7.45 (m, 4H, Ar),
7.51-7.64 (m, 3H, Ar), 7.68-7.76 (m, 1H, Ar). 13C NMR
(CDCl3, 75.5 MHz, 35 °C): δ 23.6 (OCCH3), 26.5 (CH2 of cod),
29.2 (CH2 of cod), 29.9 (CH2 of cod), 35.5 (CH2 of cod), 43.2
(NCH3), 48.5 (dCH of cod), 53.3 (dCH of cod), 81.2 (dCH of
cod), 85.7 (dCH of cod), 104.6 (CH, N-Ph), 106.3 (CH, permidine
ring), 119.4, 120.3 (CH), 120.7 (CH), 127.2 (CH, perimidine ring),
127.7 (CH), 127.8 (CH), 128.5 (CH), 128.6 (CH), 129.9 (CH),
131.3 (CH, permidine ring), 134.3, 136.0, 137.5, 140.1, 176.9
(CdO), 205.5 (IrdC). IR (NaCl film, cm-1): ν~ 3061, 2962,
2933, 2911, 2879, 2831, 1635, 1584, 1528, 1493, 1426, 1380, 1342,
1120, 1082, 815, 760, 719, 697, 669. Anal. Calcd for C28H29IrN2O2-
(CH2Cl2)0.33: C, 52.67; H, 4.63; N, 4.34. Found: C, 52.78; H, 4.39;
N, 4.38.
Synthesis of (C∧C:)2Ir(OAc) (C:∧C = C∧MeNPhNcarbene, 6).
1H NMR (CDCl3, 300 MHz, 35 °C): δ1.81 (s, 6H, CH3COO), 3.97
(s, 12H, NCH3), 6.52 (dd, J = 7.1 and 7.4 Hz, 2H, Ar), 6.67-6.76
(m, 4H, Ar), 6.86 (dd, J = 1.5 and 6.3 Hz, 2H, Ar), 7.40-7.51 (m,
8H, Ar), 7.68 (d, J = 7.8 Hz, 2H, Ar), 7.78 (dd, J = 2.7 and 5.4 Hz,
2H, Ar). 13C NMR (CDCl3, 75.5 MHz, 35 °C): δ 24.5 (OCCH3),
42.4 (NCH3), 106.3, 110.4, 112.0, 120.5, 121.0, 121.4, 122.2, 124.0,
Synthesis of (C∧C:)(C∧N)Ir(OC(O)Ph) (8d). Toluene (30 mL)
was added to a Schlenk containing 3d (0.508 g, 7.5 ꢀ 10-1 mmol)
and 2-phenylpyridine (0.115 g, 7.5 ꢀ 10-1 mmol) at room
temperature. The reaction mixture was heated at 120 °C for
24 h under an argon atmosphere. The mixture was cooled to

Article
Organometallics, Vol. 29, No. 18, 2010 4129
1
ambient temperature, and the solvent was evaporated. The result-
ing solid was washed with hexane (15 mL) and ether (15 mL) to give
a yellow powder of 8d in 94% yield (0.517 g, 7.1 ꢀ 10-1 mmol), mp
>270 °C (dec). 1H NMR (C6D6, 400 MHz, 35 °C): δ 3.91 (s, 3H,
NCH3), 6.10 (d, J = 7.5 Hz, 1H, perimidine ring), 6.36 (t, J = 6.4
Hz,1H,py),6.49(d,J=7.5Hz,1H,N-Ph),6.62(t,J= 7.5 Hz, 1H,
N-Ph), 6.74 (t, J = 7.5 Hz, 1H, py-Ph), 6.76 (t, J = 7.5 Hz, 1H,
N-Ph), 6.87 (t, J = 7.9 Hz, 2H, py and py-Ph), 6.93 (t, J = 8.1 Hz,
1H, perimidine ring), 6.99 (t, J = 8.1 Hz, 1H, perimidine ring),
7.07-7.12 (m, 6H, 1H for Ph-py; 2H for perimidine ring; 3H for m,
p-O2CPh), 7.30 (d, J = 8.2 Hz, 1H, py), 7.42 (d, J = 7.8 Hz, 1H,
perimidine ring), 7.47 (d, J = 7.8 Hz, 1H, Ph-py), 7.64 (d, J = 8.1
Hz, 1H, N-Ph), 8.33-8.34 (m, 2H, o-O2CPh), 8.86 (d, J = 5.3 Hz,
1H, py). 13C NMR (C6D6, 100 MHz, 35 °C): δ 42.8 (NCH3), 107.0
(CH, perimidine ring), 110.7 (CH, perimidine ring), 112.9, 118.9
(py), 121.3 (CH, perimidine ring), 122.6 (py), 124.1 (N-Ph), 124.8,
125.2 (py-Ph), 127.6 (CH, perimidine ring), 127.7 (CH, perimidine
ring), 127.8, 128.3, 128.4, 128.7, 129.9 (CH, O2CPh-o), 130.5 (py-
Ph), 132.6 (CH, O2CPh-p), 133.5, 134.0 (N-Ph), 135.2, 135.8, 138.1
(py), 138.8 (N-Ph), 144.6 (N-Ph), 147.8 (py), 153.0 (N-Ph), 165.9
(py), 193.9 (IrdC); some carbon resonances are overlapped with
C6D6 signals. IR (KBr tablet, cm-1): ν~ 3448, 3050, 1633, 1603,
1586, 1516, 1477, 1421, 1385, 1319, 1265, 1064, 1030, 860, 817, 755,
719, 687. MS (FAB): m/z 725 (Mþ).
(48.0 mg, 5.8 ꢀ 10-2 mmol), mp >270 °C. H NMR (CDCl3,
300 MHz, 35 °C): δ 1.62 (s, 6H, OCCH3), 3.88 (s, 6H, NCH3),
5.01 (s, 1H, OCCH), 6.56 (t, J = 7.5 Hz, 2H, Ar), 6.74 (dd, J =
8.1 and 8.2 Hz, 2H), 6.82 (dd, J = 2.4 and 6.3 Hz, 2H, Ar), 6.87
(dd, J = 1.5 and 7.5 Hz, 2H, Ar), 7.39-7.49 (m, 8H, Ar), 7.69 (d,
J = 8.1 Hz, 2H, Ar), 7.79 (d, J = 7.2 Hz, 2H, Ar). 13C NMR
(CDCl3, 75.5 MHz, 35 °C): δ 28.0 (OCCH), 40.4 (NCH3), 100.8,
106.0, 110.0, 111.6, 120.1, 120.4, 121.3, 121.9, 124.0, 127.26,
127.34, 129.5, 133.1, 134.5, 135.0, 139.5, 152.6, 185.9 (CdO),
206.5 (IrdC). IR (KBr tablet, cm-1): ν~ 3057, 2959, 2907, 1633,
1585, 1516, 1480, 1455, 1420, 1380, 1349, 1318, 1260, 1223, 1108,
1078, 1030, 816, 744. MS (FAB): m/z 707 ([M - acac]þ).
X-ray Crystallographic Analysis. All crystals were handled
similarly. The crystals were mounted on the CryoLoop
(Hampton Research Corp.) with a layer of light mineral oil and
placed in a nitrogen stream at 120(1) K. Measurements were
made on a Rigaku RAXIS-RAPID imaging plate diffrac-
tometer or Rigaku Mercury CCD area detector with graphite-
monochromated Mo KR radiation (λ = 0.71075). Crystal
data and structure refinement parameters are summarized in
Table S5.
The structures were solved by direct methods (SIR 92,19
SIR2004,20 or SHELXS9721) and refined on F2 by full-matrix
least-squares methods, using SHELXL-97.21 Non-hydrogen
atoms were anisotropically refined. H-atoms were included in
Synthesis of N-Methyl-N-pentadeuteriophenylperimidinium
Iodide ([MeNC6D5Ncarbene-H][ I], 1a-d5). 1H NMR (CDCl3, 400
MHz, 35 °C): δ 3.77 (s, 3H, CH3), 6.34 (d, J = 7.7 Hz, 1H, Ar),
6.85 (d, J = 7.5 Hz, 1H, Ar), 7.25 (t, J = 8.0 Hz, 1H, Ar), 7.44 (t,
J = 7.3 Hz, 1H, Ar), 7.48 (d, J = 8.8 Hz, 1H, Ar), 7.54 (d, J = 8.5
Hz, 1H, Ar), 9.60 (s, 1H, NCHN). 13C NMR (CDCl3, 100 MHz,
35 °C): δ 39.9, 108.0, 109.3, 121.2, 124.4, 124.9, 128.0, 128.4, 133.0,
134.3, 134.9, 151.7. IR (KBr tablet, cm-1): ν~ 3448, 3030, 2270,
1661, 1605, 1589, 1555, 1496, 1424, 1384, 1349, 1258, 1228, 1144,
815, 762, 635. MS (FAB): m/z 264 ([MeNC6D5Ncarbene-H]þ).
the refinement on calculated positions riding on their carrier
P
2
2 2
atoms. The function minimized was [ w(Fo - Fc ) ] (w =
1/[σ2(Fo2) þ (aP)2 þ bP]), where P = (Max(Fo2,0) þ 2Fc )/3 with
2
σ2(Fo2) from counting statistics. The functions R1 and wR2 were
P
P
P
P
||Fo| - |Fc||)/ |Fo| and [ w(Fo - Fc ) / (wFo4)]1/2, re-
2
2 2
(
spectively. The ORTEP-3 program22 was used to draw the
molecules.
Emission Lifetime Measurement. The light source for the
picosecond time-resolved measurement was the second harmo-
nic (355 nm) of a Ti:sapphire laser (Spectra Physics, Tsunami)
generated in a type I BBO crystal, and the repetition rate was
reduced to 500 kHz with a power of 1-2 μW by an EO
modulator (Conoptics). The emission band at 550-560 nm of
the iridium complexes was detected at the magic angle config-
uration utilizing a polarizer and a half-wave plate. A photo-
multiplier tube (Hamamatsu Photonics, R3809U-50) with an
amplifier (Hamamatsu Photonics, C5594) and a TCSPC module
(PicoQuant, PicoHarp 300) were used for the signal detection. A
monochromator (Newport, Oriel 77250) was placed in front
of the photomultiplier tube for the wavelength selection. The
system response time was determined to be 32 ps full-width
at half-maximum (fwhm) by scattered light from a colloidal
solution.
1
Synthesis of (C∧C:-d4)(C∧N)Ir(OC(O)Ph) (8-(C∧C:-d4)). H
NMR (C6D6, 400 MHz, 35 °C): δ 3.91 (s, 3H, NCH3), 6.10 (d,
J = 7.5 Hz, 1H, perimidine ring), 6.36 (t, J = 6.4 Hz, 1H, py),
6.74 (t, J = 7.5 Hz, 1H, py-Ph), 6.87 (t, J = 7.9 Hz, 2H, py and
py-Ph), 6.93 (t, J = 8.1 Hz, 1H, perimidine ring), 6.99 (t, J = 8.1
Hz, 1H, perimidine ring), 7.07-7.12 (m, 6H, 1H for Ph-py; 2H
for perimidine ring; 3H for m,p-O2CPh), 7.30 (d, J = 8.2 Hz, 1H,
py), 7.42 (d, J = 7.8 Hz, 1H, perimidine ring), 7.47 (d, J =
7.8 Hz, 1H, Ph-py), 8.33-8.34 (m, 2H, o-O2CPh), 8.86 (d, J =
5.3 Hz, 1H, py).
Synthesis of (C∧C:)(C∧N-d4)Ir(OC(O)Ph) (8-(C∧N-d4)). 1H
NMR (C6D6, 400 MHz, 35 °C): δ 3.91 (s, 3H, NCH3), 6.10 (d,
J = 7.5 Hz, 1H, perimidine ring), 6.36 (t, J = 6.4 Hz, 1H, py),
6.49 (d, J = 7.5 Hz, 1H, N-Ph), 6.62 (t, J = 7.5 Hz, 1H, N-Ph),
6.76 (t, J = 7.5 Hz, 1H, N-Ph), 6.87 (t, J = 7.9 Hz, 1H, py), 6.93
(t, J = 8.1 Hz, 1H, perimidine ring), 6.99 (t, J = 8.1 Hz, 1H,
perimidine ring), 7.07-7.12 (m, 5H, 2H for perimidine ring; 3H
for m,p-O2CPh), 7.30 (d, J = 8.2 Hz, 1H, py), 7.42 (d, J = 7.8
Hz, 1H, perimidine ring), 7.64 (d, J = 8.1 Hz, 1H, N-Ph),
8.33-8.34 (m, 2H, o-O2CPh), 8.86 (d, J = 5.3 Hz, 1H, py).
Synthesis of (C∧C:)2Ir(acac) (11). Toluene (5 mL) was added
to a Schlenk containing LiN(SiMe3)2 (58.0 mg, 3.50 ꢀ 10-1
mmol), [IrCl(cod)]2 (58.0 mg, 8.70 ꢀ 10-2 mmol), 1a (135.0 mg,
3.48 ꢀ 10-2 mmol), and AgOAc (297.0 mg, 1.78 mmol) at room
temperature. The reaction mixture was stirred for 1 h at room
temperature and then refluxed for 24 h. After evaporation of all
the solvent, the iridium compound was extracted with CH2Cl2.
The extract was concentrated, and hexane was added to form a
yellow powder, which was dried in vacuo. The yellow powder
was dissolved in toluene (5 mL), and Na2CO3 (95.0 mg, 8.90 ꢀ
10-1 mmol) and acetylacetone (0.18 mL, 1.70 mmol) were
added. The reaction mixture was stirred for 1 h at room
temperature and then refluxed for 6 h. After evaporation of all
the solvent, the iridium compound was extracted with CH2Cl2.
All the solvent was evaporated, and the resulting solid was
washed with hexane to give a yellow powder of 11 in 33% yield
Acknowledgment. H.T. acknowledges financial sup-
port from a Grant-in-Aid for Young Scientists (B). This
work was supported by the Core Research for Evolu-
tional Science and Technology (CREST) program of the
Japan Science and Technology Agency (JST), Japan.
Supporting Information Available: Molecular structures of 4a,
4b, and 8c, excitation spectra, and emission decay of 11, crystal-
lographic data for 3a, 3b, 3c, 4a, 4b, 5, 7, 8c, 8d, and 11, and their
CIF files. These materials are available free of charge via the
Internet at http://pubs.acs.org.
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