Alkyne insertion induced regiospecific C-H activation with [Cp*MCl2]2 (M = Ir, Rh)

Article abstract of DOI:10.1021/om101064v

Regiospecific ortho-C2_pyrene-H bond activation of a pyrene-based imine ligand was first promoted by sodium acetate with [Cp*IrCl ₂]₂ to form a half-sandwich cycloiridation complex. Internal and terminal alkynes were then f

Full text of DOI:10.1021/om101064v

Organometallics 2011, 30, 905–911 905
DOI: 10.1021/om101064v
Alkyne Insertion Induced Regiospecific C-H Activation
with [Cp*MCl2]2 (M = Ir, Rh)
Ying-Feng Han, Hao Li, Ping Hu, and Guo-Xin Jin*
Shanghai Key Laboratory of Molecular Catalysis and Innovative Material, Department of Chemistry,
Fudan University, Shanghai, 200433, People’s Republic of China
Received November 11, 2010
Regiospecific ortho-C2pyrene-H bond activation of a pyrene-based imine ligand was first promoted
by sodium acetate with [Cp*IrCl2]2 to form a half-sandwich cycloiridation complex. Internal and
terminal alkynes were then found to insert into the Ir-C2pyrene bond of a cycloiridation complex,
which induced another regiospecific peri-C80naphthyl-H bond activation: different coordination
modes of the alkynes group were captured. Unlike the iridium-based insertion complex, which is
very stable, the rhodium-catalyzed oxidative coupling of an aromatic imine with an internal alkyne
effectively proceeds via regioselective C-H bond activation to produce an indenone imine
product. All the intermediate compounds following C-H activation, alkyne insertion and reduction,
as well as indenone imine product were fully characterized, including the determination of X-ray
structures.
Introduction
cyclometalation of dimethylbenzylamine with [Cp*IrCl2]2
showed the metal acetate provides electrophilic activation
of the C-H bond and acts as an intramolecular base for the
deprotonation in the process.4 Jones’ group5 has employed a
similar methodology to prepare cyclometalated compounds
with phenylimines and 2-phenylpyridines. Dimethylacetyle-
nedicarboxylate (DMAD) was then found to insert into the
metal-carbon bonds of the cyclometalated compounds, and
then the isoquinoline salts were obtained through oxidative
coupling reactions. Compared to alkyne insertion into pal-
ladium-aryl and nickel-aryl, which often gives multiple-
insertion adducts,6 clean monoinsertion products could be
obtained in high yields when cyclometalated Cp*Rh and
Cp*Ir undergo alkyne insertion reactions.3,5,7
In the past half century, aromatic C-H activation media-
ted by transition metals has been investigated because of
their potential use in many organic reactions and applica-
tions in industry.1 The formation of cyclometalated com-
plexes is a key step for the development of synthetic applica-
tions. In particular, metalation of an ortho C-H bond of a
substituted phenyl to form a five-membered metallacycle
with nitrogen-containing ligands is common.2 Recently, a
new, efficient route to the formation of nitrogen-containing
half-sandwich cyclometalated complexes with [Cp*MCl2]2
(M = Rh, Ir) in the presence of sodium acetate was reported
by the Davies group.3 Density functional calculations on the
Using sodium acetate for certain substrates the C-H bonds
were cleaved at room temperature, and the expected cyclo-
metalated complexes were formed almost stoichiometrically
*Corresponding author. Tel: þ86-21-65643776. Fax:
þ
86-21-
65641740. E-mail: gxjin@fudan.edu.cn.
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2011 American Chemical Society
Published on Web 01/18/2011
pubs.acs.org/Organometallics

906 Organometallics, Vol. 30, No. 4, 2011
Han et al.
with [Cp*MCl2]2 (M = Rh, Ir).3-5 On the other hand, it was
necessary to prepare these cyclometalated complexes sepa-
rately so that the catalytic reactions and mechanisms could
be fully investigated. When a ligand has two or more activ-
ated C-H bonds, the problem of cyclometalation regios-
electivity and subsequent regioselective functionalization at
the metalated carbon can be an issue. The regioselectivity of
the cyclopalladation has two different levels, reviewed by
Ryabov:1b the more trivial level, referred to as enforced
regioselectivity, when electronic, steric, or other factors make
only one route of cyclometalation possible, and the second
level, referred to as regulated regioselectivity, in which any
path of cyclometalation is available through changing the
reaction conditions. Compared to C(phenyl)-H bond activ-
ation, which has been studied extensively,1-7 C(naphthyl)-H
bond activation in peri-(C8naphthyl) position has received less
attention. Two examples of regiospecific peri-C8naphthyl-H
bond activation of 1-(20-X-50-methylphenylazo)naphthalene
(X = OH, OMe) by disodium tetrachloropalladate and one
example of regiospecific peri-C8naphthyl-H bond activa-
tion of N-(naphthyl)picolinamide with [Ir(PPh3)3Cl] were
reported.8a-d Bicyclometalation of aromatic substrates
containing imine anchoring groups has been achieved with
a dimethyliron complex at low temperature.8e
Recently, we have developed an efficient one-pot method
for synthesizing molecular macrocycles of half-sandwich
iridium complexes via C-H activation directed muticompo-
nent self-assembly under mild conditions. An approach for
postsynthetic modification of organometallic macrocycles
through DMAD insertion has been employed.9 Herein, we
report (i) the first example to our knowledge of the con-
trollable iridium-promoted double C-H activation in one
molecule: the alkyne insertion induced a second C-H activ-
ation on the rarely activated peri-C80naphthyl position;
(ii) stabilized by the newly formed Ir-C bond, different
coordination modes of the alkyne groups were captured
when using internal and terminal alkynes, which may pro-
vide information about the mechanism of the alkyne inser-
tion process, (iii) the rhodium-catalyzed oxidative coupling
of an aromatic imine with internal alkyne effectively pro-
ceeds via regioselective C-H bond activation to produce an
indenone imine product.
Scheme 1. Synthesis of 2a-d
the C1, C3, C6, and C8 positions were employed in the synthe-
ses of the σ-bonded organometallic pyrene complexes.11
1-Diphenylphosphinopyrene and 1,6-bis(diphenylphosphino)-
pyrene can be metalated at C5 and C10 to give cycloplatina-
tion complexes.12 The pyridine-substituted pyrene ligand
4-methyl-2-pyren-1-ylpyridine is known to undergo cyclo-
metalation reactions with IrCl3 in trimethyl phosphate.13
The cyclometalation occurred only at the 2-position with the
formation of a five-membered cyclometalated ring, instead
of at the 10-position of the pyrene moiety with formation of a
six-membered cyclometalated ring. From the viewpoint of
synthetic applications, development of C-H activation re-
actions for pyrene-based substrates would substantially im-
prove the versatility and usefulness of this reaction. There-
fore, we chose a series of pyrene-based imines as substrates to
investigate the regioselectivity for C-H activation.
Independent treatment of 1a-d with [Cp*IrCl2]2 in di-
chloromethane at room temperature in the presence of
sodium acetate gave a series of mononuclear complexes in
good yields, as shown in Scheme 1. While the electron-
withdrawing substituent (p-Cl) inhibits C-H activation,
the electron-donating substituent (p-OMe) benefits C-H
activation, which is similar to the effects observed in aro-
matic C-H activation of substituted phenylimines promoted
by sodium acetate with [Cp*MCl2]2 (M = Ir, Rh) to form
monocyclometalated complexes.5b
Crystals of 2b suitable for an X-ray diffraction study were
obtained by slow diffusion of diethyl ether into a concen-
trated solution of the complexes in dichloromethane at low
temperature. According to X-ray crystallographic analysis
of 2b, the cycloiridation reaction takes place at the C2
position with the formation of a five-membered ring, the
same as the expected piano-stool type geometry. A perspec-
tive drawing of 2b with selected atomic numbering scheme,
bond lengths, and angles is given in Figure 1. The Ir(1)-N(1)
Results and Discussion
Because of their intense fluorescence, excimeric formation,
and fluorescence anisotropy, the synthesis of pyrene-based
derivatives has been extensively studied by many groups.10
Bromopyrenes or their corresponding lithiated pyrenes at
˚
bond length [2.087(4) A] and C(3)-Ir(1)-N(1) angle
˚
[77.62(17)°] are very similar to those [2.0881(15) A and
(8) (a) Hugentobler, M.; Klaus, A. J.; Mettler, H.; Rys, P.; Wehrle, G.
Helv. Chim. Acta 1982, 65, 1202. (b) Neogi, D. N.; Das, P.; Biswas, A. N.;
Bandyopadhyay, P. Polyhedron 2006, 25, 2149. (c) Neogi, D. N.; Biswas,
A. N.; Das, P.; Bhawmick, R.; Bandyopadhyay, P. Inorg. Chim. Acta 2007,
360, 2181. (d) Dasgupta, M.; Tadesse, H.; Blake, A. J.; Bhattacharya, S.
J. Organomet. Chem. 2008, 693, 3281. (e) Klein, H.-F.; Camadanli, S.;
77.76(6)°] in the related cycloiridation complex [Cp*Ir(L1)Cl]
(L1H = N-(4-methoxybenzylidene)aniline).5b
The pyrene-based imine ligand 3 is easily synthesized
by the reaction of 1-pyrenecarboxaldehyde with naphtha-
lene-1-amine. As shown in Scheme 2, the C-H activation
in 3 can offer some different positions for cyclometalation:
€
Becka, R.; Florke, U. Chem. Commun. 2005, 381.
(9) Han, Y.-F.; Li, H.; Weng, L.-H.; Jin, G.-X. Chem. Commun. 2010,
3556.
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Interscience: London, 1970. (b) Moon, S.-Y.; Youn, N. J.; Park, S. M.;
Chang, S.-K. J. Org. Chem. 2005, 70, 2394. (c) Fujimoto, K.; Muto, Y.;
Inouye, M. Chem. Commun. 2005, 4780. (d) Sharma, J.; Tleugabulova, D.;
Czardybon, W.; Brennan, J. D. J. Am. Chem. Soc. 2006, 128, 5496.
(e) Mcqueen, E. W.; Goldsmith, J. I. J. Am. Chem. Soc. 2009, 131,
17554. (f) Stylianou, K. C.; Heck, R.; Chong, S. Y.; Bacsa, J.; Jones,
J. T. A.; Khimyak, Y. Z.; Bradshaw, D.; Rosseinsky, M. J. J. Am. Chem.
Soc. 2010, 132, 4119.
(11) (a) Weisemann, C.; Schmidtberg, G.; Brune, H.-A. J. Organo-
met. Chem. 1989, 365, 403. (b) Yam, V. W.-W.; Choi, S. W.-K.; Cheung,
K.-K. Dalton Trans. 1996, 3411. (c) Heng, W. Y.; Hu, J.; Yip, J. H. K.
Organometallics 2007, 26, 6760. (d) Partyka, D. V.; Esswein, A. J.; Zeller,
M.; Hunter, A. D.; Gray, T. G. Organometallics 2007, 26, 3279.
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25, 1461.

Article
Organometallics, Vol. 30, No. 4, 2011 907
ortho-(C2pyrene), peri-(C80naphthyl), and C10pyrene. Cyclome-
talation at the ortho-(C2pyrene) or peri-(C80naphthyl) position
would lead to the formation of a five-membered metalla-
cycle, while cyclometalation at C10pyrene would give a six-
membered metallacycle. In addition, the C-H bond clea-
vage of the imine group can also occur under the right con-
ditions.7e
Actually, when ligand 3 was treated with [Cp*IrCl2]2 in
dichloromethane at room temperature in the presence of
sodium acetate, only the ortho-(C2pyrene) C-H activation
hap0pened, affording complex 4 in high yield. No peri-
(C8 naphthyl) or C10pyrene C-H activation product was found
even on increasing the temperature, using polar solvents, or
using excess [Cp*IrCl2]2. The 1H NMR spectrum of complex
4 showed three singlet resonances at δ 9.28, 8.58, and 1.57 ppm
due to HCdN, H3, and the Cp* ring, respectively. As
expected, two aromatic regions were observed in the ranges
δ 7.92-8.43 and 7.24-7.74 ppm due to the other protons of
the pyrene and naphthalene rings. Crystals of complex 4
suitable for an X-ray diffraction study were obtained by slow
diffusion of diethyl ether into a concentrated solution of the
complex in dichloromethane at low temperature. According
to X-ray crystallographic analysis of complex 4, the cycloir-
idation reaction takes place at the C2 position of the pyrene
group with the formation of a five-membered metallacycle,
the same as that found in complex 2b. A perspective drawing
of complex 4 with selected atomic numbering scheme, bond
lengths, and angles is given in Figure 2. The Ir(1)-N(1) bond
˚
length [2.056(7) A] and C(2)-Ir(1)-N(1) angle [77.8(3)°] are
˚
very similar to those [2.0881(15) A and 77.76(6)°] in the
related cycloiridation complexes.
Reaction of DMAD with complex 4 at 40 °C in dichloro-
methane, as shown in Scheme 2, gave complex 5 in good
yield. Complex 5 is an air and thermally stable red solid that
has been fully characterized by NMR spectroscopy, elemen-
tal analysis, and X-ray crystallography. To our surprise,
besides a single alkyne insertion into Ir-C2pyrene, another
new C-H activation at peri-C80naphthyl-H was also ob-
served. Compared with C(phenyl)-H bond activation,
which has been studied extensively, only a few examples of
the C(naphthyl)-H bond activation in peri-(C80naphthyl
)
position have been reported. As evident by 1H NMR spec-
troscopy in CDCl3, the appearance of two sharp singlets at δ
3.58 and 3.25 ppm were due to the COOMe protons. The
resonances of the HCdN and Cp* protons were shifted from
δ 9.28 and 1.57 to δ 10.05 and 1.13, respectively. As shown in
Figure 3, the molecular structure of complex 5 shows a
distorted seven-membered metallacycle, and a0newly formed
five-membered iridacycle through the peri-(C8 naphthyl) C-H
activation. Such a structure is very similar to the heteroatom-
substituted cyclohept(a)acenaphthylene ring system.14 It is
Figure 1. Molecular structure of 2b with 30% displacement
ellipsoids. All H atoms are omitted for clarity. Selected bond
distances (A) and angles (deg): Ir(1)-C(2) 2.035(5), Ir(1)-N(1)
2.087(4), Ir(1)-Cl(1) 2.3992(14), N(1)-C(17) 1.284(5), N-
(1)-C(18) 1.447(6), C(1)-C(17) 1.413(6), C(1)-C(2) 1.418(7);
C(2)-Ir(1)-N(1) 77.62(17), C(2)-Ir(1)-Cl(1) 86.12(13), N-
(1)-Ir(1)-Cl(1) 85.53(11), C(17)-N(1)-Ir(1) 116.1(3), C-
(18)-N(1)-Ir(1) 125.1(3), C(17)-C(1)-C(2) 113.5(4).
˚
Scheme 2. Synthesis of 4-8

908 Organometallics, Vol. 30, No. 4, 2011
Han et al.
Figure 4. Molecular structure of 6 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity.
Selected distances (A) and angles (deg) for 6: Ir(1)-C(20)
2.047(7), Ir(1)-C(29) 2.056(6), Ir(1)-N(1) 2.142(5), N(1)-
C(17) 1.487(7), C(2)-C(28) 1.479(8), C(28)-C(29) 1.352(8);
C(20)-Ir(1)-C(29) 89.7(2), C(20)-Ir(1)-N(1) 79.3(2), C(29)-
Ir(1)-N(1) 90.8(2).
Figure 2. Molecular structure of 4 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity.
Selected distances (A) and angles (deg): Ir(1)-C(2) 2.029(8),
Ir(1)-N(1) 2.056(7), N(1)-C(17) 1.312(10); C(2)-Ir(1)-N(1)
77.8(3), C(17)-N(1)-Ir(1) 118.8(5), C(2)-C(1)-C(17) 113.3(7),
C(1)-C(2)-Ir(1) 115.4(6), N(1)-C(17)-C(1) 114.6(7). Symme-
try transformations used to generate equivalent atoms: 1-x,
1-y, 2-z.
˚
˚
Figure 5. Molecular structures of 7 with thermal ellipsoids
drawn at the 30% level. Cl and H atoms are omitted for clarity.
˚
Selected distances (A) and angles (deg): Ir(1)-N(1) 2.062(7),
Figure 3. Molecular structure of 5 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity.
Selected distances (A) and angles (deg): Ir(1)-N(1) 2.085(4),
Ir(1)-C(20) 2.044(5), Ir(1)-C(29) 2.046(5), N(1)-C(17) 1.278(6),
C(28)-C(29) 1.350(7); C(20)-Ir(1)-C(29) 92.9(2), C(20)-Ir-
(1)-N(1) 78.8(2), C(29)-Ir(1)-N(1) 84.19(18).
Ir(1)-C(20) 2.076(9), Ir(1)-C(28) 2.130(8), Ir(1)-C(29)
2.179(8), N(1)-C(17) 1.292(9), C(28)-C(29) 1.404(10); N(1)-
Ir(1)-C(20) 78.5(3), N(1)-Ir(1)-C(28) 87.0(3), C(20)-Ir(1)-
C(28) 120.1(3), N(1)-Ir(1)-C(29) 84.0(3), C(20)-Ir(1)-
C(29) 82.5(3), C(28)-Ir(1)-C(29) 38.0(3).
˚
also interesting to note that the newly formed Ir-C80naphthyl
bond was stable and free from further insertion even when an
excess amount of DMAD was used. The sequential reaction of
C-H activation and alkyne insertion in one pot was also exam-
ined, and the expected complex 5 was formed in 76% yield.
In order to explore the reactivity, we treated complex 5
with an excess of sodium borohydride in methanol/dichloro-
methane (v/v = 1:1). A rapid color change from dark red to
pale yellow was observed, affording complex 6 in 95% yield
(Scheme 2). The detailed structure of complex 6 was con-
firmed by the single-crystal X-ray analysis, as shown in
Figure 4, with selected bond distances and angles. The
6 in CDCl3 showed two doublets at δ 5.40 and 5.71 ppm in a
1:1 integration ratio, which indicates the existence of a
methylene group, and one multiplet at approximately δ
4.40 ppm belongs to an NH proton. In addition, the signal
for Cp* was observed at δ 0.98 ppm, more than 0.14 ppm
upfield from the corresponding signal in complex 5.
We also investigated the reaction of a terminal alkyne with
complex 4. When complex 4 was treated with PhCtCH in
1:1 ratio in dichloromethane after 102 h, a monoinsertion-
induced C-H activation at peri-C8 naphthyl-H led to the
1
formation of complex 7 in 71% yield. The H NMR spec-
trum of the product showed two resonances for olefinic
protons at δ 4.28 and 6.08 ppm, indicating that the olefinic
group is coordinating to the metal center. A singlet at δ 1.21
ppm assigned to Cp* protons is 0.38 ppm upfield compared
with complex 4, suggesting the influence of a ring current.
Fortunately, we were able to obtain suitable crystals of
˚
N(1)-C(17) bond length [1.487(7) A] is longer than that in
complex 5 [1.278(6) A], implying the imine group was
˚
reduced to a single bond. The 1H NMR spectrum of complex
(14) White, C.; Yates, A.; Maitles, P. M. Inorg. Synth. 1992, 29, 228.

Article
Organometallics, Vol. 30, No. 4, 2011 909
decrease of conjugation, due to the non-coplannar structure
of the ligand, in complex 5 and reduction of the CdN group
in complex 6. It turns out that the luminescence emission of
the pyrene group is quenched by the direct bonding to the
metal in complex 4 and reappeared after the insertion of
alkyne to the M-C bond. The fact that the UV-vis and
luminescence emission spectra are so different in spite of the
similarity of the organic portion of the molecule suggests that
the differences involve the iridium center.
Conclusion
In conclusion, we have established that regiospecific peri-
C80naphthyl-H bond activation under very mild conditions
was induced by the insertion of alkynes into the Ir-C bond
of half-sandwich cycloiridation complexes. The efficient
rhodium-catalyzed oxidative coupling of an aromatic imine
with an alkyne accompanied by regioselective C-H bond
cleavage also was described. These C-H bond activation
reactions provide efficient routes to pyrene- or/and naphthyl-
based derivatives, which are useful intermediates for organic
materials and medicines. Further studies of the scope and
mechanism of alkyne insertion reaction induced regiospecific
peri-C80naphthyl-H bond activation are currenly under in-
vestigation.
Figure 6. Molecular structure of 8 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity.
Selected distances (A) and angles (deg): C(1)-C(2) 1.408(3),
C(1)-C(17) 1.480(3), C(17)-N(1) 1.283(3), C(17)-C(28)
1.492(3), C(28)-C(29) 1.352(3), C(18)-N(1) 1.419(2); C(1)-C-
(2)-C(29) 107.84(16), N(1)-C(17)-C(1) 124.10(19), N(1)-C-
(17)-C(28) 130.03(18), C(1)-C(17)-C(28) 105.74(16), C(29)-
C(28)-C(17) 108.92(17), C(28)-C(29)-C(2) 109.60(18).
˚
Experimental Section
complex 7 and determined its structure by X-ray crystal-
lographic analysis. As shown in Figure 5, the structure shows
that C-H activation at peri-C80naphthyl-H occurred, form-
ing a new Ir-C80naphthyl bond. However, unlike complex 5,
the structure of 7 shows that the metal centers coordinated
with the inserted alkyne through a π-bonding mode. The
phenyl of the alkyne is on the carbon atom next to the metal
General Comments. General Data. All reactions and manip-
ulations were performed under a nitrogen atmosphere, using
standard Schlenk techniques. However, once the reactions were
completed, subsequent workups were done without precaution,
as the compounds are air-stable. Solvents were purified by
standard methods prior to use. [Cp*MCl2]2 (M = Ir, Rh) were
prepared according to the reported procedures,14 while other
chemicals were obtained commercially and used without further
purification. IR spectra were recorded on a Nicolet AVATAR-
360 IR spectrometer; UV-vis absorption spectra were mea-
sured using an Agilent HP8453 spectrophotometer, and lumi-
nescence emission spectra were recorded on a Vavian Cary
Eclipse fluorescence spectrometer at room temperature under
nitrogen atmosphere. Elemental analyses were carried out with
an Elementar III Vario EI analyzer; the samples were dried
˚
center. The bond lengths of Ir(1)-C(28) [2.130(8) A] and
˚
Ir(1)-C(29) [2.179(8) A] are very close to each other, con-
firming the η2-interaction between the alkene carbon atoms
and metal center.
Complex 5 was also treated with excess CO, PPh3, or
Cu(OAc)2 H2O, but no reaction was observed at high
3
temperature in different solvents. However, the rhodium-
catalyzed oxidative coupling of aromatic imine 1 with
DMAD effectively proceeds via regioselective C-H bond
cleavage to produce indenone imine 8. Actually, when the
reaction of C-H activation and alkyne insertion in one pot
was catalyzed by [Cp*RhCl2]2, after 8 h, though 5b was not
observed, the indenone imine 8 was obtained in good yield.
In addition, the synthesis of indenone imine 8 can be easily
realized via rhodium-catalyzed oxidative coupling of an
aromatic imine with alkyne in the presence of excess Cu-
1
under vacuum for 10 h before analyses. H NMR (400 MHz)
spectra were obtained on a Bruker DMX-400 spectrometer in
CDCl3 (δ 7.26) or CD3OD (δ 3.31) solution.
Procedure for the Reaction of [Cp*IrCl2]2 and Ligands 1a-d. A
mixture of [Cp*IrCl2]2 (40 mg, 0.05 mmol), NaOAc (25 mg, 0.3
mmol), and ligand (0.1 mmol) was stirred at 50 °C in 20 mL of
dichloromethane for 6 h. The mixture was filtered through
Celite and evaporated to afford a red solid, which was further
purified by silica gel column chromatography to afford the
corresponding cyclometalated complex.
(OAc)2 H2O.7e Indenone imine 8 can be recognized and
3
characterized by 1H NMR spectroscopy and its single-crys-
tal X-ray structure (Figure 6).
UV-vis absorbance behaviors of ligand 3 and complexes
4, 5, and 6 were investigated (Figure S1). In the UV-vis
absorption spectrum of complex 4, an obvious metal-ligand
charge transfer (MLCT) absorbance was observed due to the
fact that the metal is connected directly to the carbon atom of
ligand 3. Cutting the direct bonding of metal and pyrene
group by the insertion of alkyne can decrease this kind of
MLCT absorbance. When the imine group was reduced, the
visible absorbance almost disappeared completely. Signifi-
cant change can also be found in the luminescence emission
spectra of 3, 5, and 6 (Figure S2). The blue shift in the
emission spectra of 5 and 6 compared with 3 is caused by the
2a (61 mg, 92%). Anal. Calcd for C33H29ClIrN: C 59.40, H
4.38, N 2.10. Found: C 59.23, H 4.36, N 2.09. H NMR (400
1
MHz, CDCl3, ppm): δ 9.32 (s, 1H, Ha, HCdN); 8.59 (s, 1H, Hb);
8.45 (d, J = 9.3 Hz, 1H, Hc); 8.12 (d, J = 7.8 Hz, 2H, He and Hg);

910 Organometallics, Vol. 30, No. 4, 2011
Han et al.
8.05 (m, 3H, Hd, Hh, andHi); 7.92 (m, 1H, Hf);7.75(d, J =8.3Hz,
(d, J = 8.3 Hz, 1H); 7.57 (m, 3H); 7.24 (d, J = 7.8 Hz, 1H). 13
NMR (CDCl3, ppm): δ 159.23 (HCdN), 150.28, 134.14, 133.63,
131.38, 130.76, 130.71, 129.32, 129.21, 129.14, 128.65, 127.83,
127.61, 127.50, 126.61, 126.38, 126.33, 126.31, 126.09, 126.02,
125.98, 125.18, 125.08, 124.74, 124.32, 122.77, 112.95.
C
2H, Hj); 7.48 (m, 2H, Hk); 7.36 (m, 1H, Hl); 1.56 (s, 15H, C5Me5).
2b (65 mg, 93%). Anal. Calcd for C34H31ClIrNO: C 58.56, H
1
4.48, N 2.01. Found: C 58.66, H 4.24, N 2.12. H NMR (400
MHz, CDCl3, ppm): δ 9.27 (s, 1H, Ha, HCdN); 8.58 (s, 1H, Hb);
8.43 (d, J= 8.8 Hz, 1H, Hc);8.11(d,J= 7.8 Hz, 2H, He and Hg);8.04
(m,3H,Hd,Hh,andHi);7.91(m,1H,Hf);7.71(d,J= 8.8 Hz, 2H, Hj);
6.99 (d, J= 8.8 Hz, 2H, Hk); 3.90 (s, 3H, OMe); 1.57 (s, 15H, C5Me5).
Preparation of 4. A mixture of [Cp*IrCl2]2 (40 mg, 0.05
mmol), NaOAc (25 mg, 0.3 mmol), and 3 (36 mg, 0.1 mmol)
was stirred at 50 °C in 20 mL of dichloromethane for 6 h. The mix-
ture was filtered through Celite and evaporated to afford red solid,
which was further purified by silica gel column chromatography to
afford red cyclometalated compound 4 (65 mg, 91%). Anal. Calcd
for C37H31ClIrN: C 61.95, H 4.36, N 1.95. Found: C 61.77, H 4.21,
1
N1.98. H NMR (400 MHz, CDCl3, ppm): δ 9.28 (s, 1H, Ha,
HCdN); 8.58 (s, 1H, Hb); 8.43 (d, J = 8.8 Hz, 1H, Hc); 8.14 (d, J =
7.8 Hz, 2H, He and Hg); 8.05 (m, 3H, Hd, Hh, and Hi); 7.92 (m, 1H,
Hf); 7.24-7.74 (m, 7H, Hj-p); 1.57 (s, 15H, C5Me5). IR(KBr): ν
3039, 2920, 2854, 1584, 1551, 1384, 1025 cm-1
.
2c (62 mg, 89%). Anal. Calcd for C33H28Cl2IrN: C 56.48, H
1
4.02, N 2.00. Found: C 56.58, H 4.12, N 2.09. H NMR (400
MHz, CDCl3, ppm): δ 9.23 (s, 1H, Ha, HCdN); 8.57 (s, 1H, Hb);
8.42 (d, J = 9.3 Hz, 1H, Hc); 8.10 (d, J = 7.8 Hz, 2H, He and Hg);
8.03 (m, 3H, Hd, Hh, and Hi); 7.90 (m, 1H, Hf); 7.56 (d, J = 8.8 Hz,
2H, Hj); 6.74 (d, J = 8.8 Hz, 2H, Hk); 1.57 (s, 15H, C5Me5).
Preparation of 5. A mixture of 4 (36 mg, 0.05 mmol) and
DMAD (28 mg, 0.2 mmol) was stirred at 40 °C in 20 mL of
dichloromethane for 12 h. The solution was evaporated to
dryness, and the solid was further purified by silica gel column
chromatography to afford red solid 5 (35 mg, 86%). Anal. Calcd
for C43H36IrNO4: C 62.76, H 4.41, N 1.70. Found: C 62.59, H
4.26, N 1.67. 1H NMR (400 MHz, CDCl3, ppm): δ 10.05 (s, 1H,
Ha, HCdN); 8.05-8.30 (m, 8H, Hb-i); 7.84 (d, J = 7.4 Hz, 1H,
Ho); 7.73 (d, J = 7.8 Hz, 1H, Hm); 7.49 (d, J = 6.4 Hz, 1H, Hl);
7.41 (m, 2H, Hk and Hj); 7.35 (m, 1H, Hn); 3.58 (s, 3H, COOMe);
3.25 (s, 3H, COOMe); 1.13 (s, 15H, C5Me5). 13C NMR (CDCl3,
ppm): δ 175.26 (Ir-C), 171.59, 167.68, 163.54, 155.26, 153.09,
142.65, 139.40, 133.35, 132.50, 132.22, 131.34, 130.95, 130.70,
130.09, 129.41, 129.14, 129.09, 129.03, 128.90, 128.82, 127.55,
126.49, 126.24, 124.62, 124.45, 122.91, 121.72, 119.19, 110.00, 91.11
(C5Me5), 51.79 (MeOOC), 49.28 (MeOOC), 8.42 (C5Me5). IR (KBr):
2d (62 mg, 92%). Anal. Calcd for C34H31ClIrN: C 59.94, H
1
4.59, N 2.06. Found: C 59.69, H 4.32, N 2.11. H NMR (400
MHz, CDCl3, ppm): δ 9.29 (s, 1H, Ha, HCdN); 8.58 (s, 1H, Hb);
8.38 (d, J = 8.8 Hz, 1H, Hc); 8.12 (d, J = 7.8 Hz, 2H, He and Hg);
8.03 (m, 3H, Hd, Hh, and Hi); 7.92 (m, 1H, Hf); 7.21-7.37 (m, 4H,
Hj, Hk, Hl, and Hm); 2.42 (s, 3H, Me); 1.57 (s, 15H, C5Me5).
ν 3041, 2944, 2904, 1696, 1560, 1549, 1435, 1384, 1211, 1022 cm-1
.
Preparation of 3. Ligand 3 was prepared by the reaction of
1-pyrenecarboxaldehyde with one equivalent of naphthalen-1-
amine in methanol overnight at room temperature in 89% yield.
Anal. Calcd for C27H17N: C 91.24, H 4.82, N 3.94. Found: C
91.21, H 4.69, N 3.98. 1H NMR (400 MHz, CDCl3, ppm): δ 9.55
(s, 1H, Ha, HCdN); 9.18 (d, J = 9.2 Hz, 1H); 8.87 (d, J = 8.3
Hz, 1H); 8.52 (m, 1H); 8.04-8.29 (m, 7H); 7.91 (m, 1H); 7.79
Preparation of 6. NaBH4 (15 mg, 0.4 mmol) was added to
solution of 5 (41 mg, 0.05 mmol) in 20 mL of chloroform/

Article
Organometallics, Vol. 30, No. 4, 2011 911
methanol (v/v = 1:1). The red solution was changed to yellow
after 5 min, and the solid was further purified by silica gel
column chromatography to afford yellow solid 6 (39 mg, 95%).
Anal. Calcd for C43H38IrNO4: C 62.60, H 4.64, N 1.70. Found:
C 62.42, H 4.71, N 1.63. 1H NMR (400 MHz, CDCl3, ppm): δ
8.05-8.65 (m, 8H, Hb-i); 7.75 (d, J = 7.6 Hz, 1H, Ho); 7.66 (d,
J = 7.6 Hz, 1H, Hj); 7.36-7.41 (m, 4H, Hk-n); 5.71 (d, J = 11.9
Hz, 1H, Ha); 5.40 (d, J = 11.9 Hz, 1H, Ha); 4.40 (m, 1H, N-H);
3.63 (s, 3H, COOMe); 3.35 (s, 3H, COOMe); 0.98 (s, 15H,
C5Me5). IR (KBr): ν 3040, 2942, 2921, 1692, 1556, 1428, 1380,
1H); 7.90 (m, 1H); 7.72 (d, 1H); 7.56-7.60 (m, 2H); 7.43 (m, 1H);
6.83 (d, 1H); 3.97 (s, 3H, COOMe); 2.92 (s, 3H, COOMe). 13
C
NMR (500 MHz, CDCl3, ppm): δ 165.0, 163.4, 162.8, 147.0,
142.4, 136.7, 133.7, 133.3, 131.7, 131.2, 131.0, 130.5, 129.1,
129.0, 128.2, 127.6, 127.2, 126.8, 126.7, 126.5, 126.4, 126.2,
126.0, 125.6, 125.3, 124.7, 124.6, 123.9, 123.7,120.5, 115.5,
52.5 (COOMe), 51.5 (COOMe).
X-ray Structure Determinations. Intensity data for complexes
2b, 4, 5, 6, and 7 were collected on a CCD-Bruker SMART
APEX system. All the determinations of unit cell and intensity
data were performed with graphite-monochromated Mo KR
1242, 1204, 1023 cm-1
.
˚
radiation (λ = 0.71073 A), and the data were collected at room
temperature using the ω scan technique. Intensity data for 8
were collected using an Oxford Diffraction KM-4 CCD dif-
fractometer having kappa geometry and using graphite-mono-
˚
chromated Mo KR radiation (λ = 0.71073 A) at room tem-
perature. Data reduction was carried out with CrysAlis PRO.
All structures were solved by direct methods, using Fourier
techniques, and refined on F2 by a full-matrix least-squares method.
All the calculations were carried out with the SHELXTL pro-
gram.15,16
All non-hydrogen atoms of complexes 2b, 4, 5, 6, 7, and 8 were
refined anisotropically. There exist disordered solvent molecules
in complex 7, which cannot be refined properly. Therefore, the
SQUEEZE algorithm17 had to be used before the structure was
refined to convergence. In all complexes, hydrogen atoms that
could be found were placed in the geometrically calculated
positions with fixed isotropic thermal parameters. However,
the dichloromethane molecule in the asymmetric unit of com-
plex 4 is disordered so that hydrogen atoms could not be found
or calculated.
Preparation of 7. A mixture of 4 (36 mg, 0.05 mmol) and
PhCtCH (20 mg, 0.2 mmol) was stirred at 40 °C in 20 mL of
dichloromethane for 12 h. The solution was evaporated to
dryness, and the solid was further purified by silica gel column
chromatography to afford red solid 7 (29 mg, 71%). Anal. Calcd
for C45H37ClIrN: C 65.96, H 4.55, N 1.71. Found: C 65.83, H
4.26, N 1.65. 1H NMR (400 MHz, CD3OD, ppm): δ 9.18 (s, 1H,
Ha, HCdN); 6.28-8.63 (m, 19H, Hb-o and Ph); 6.08 (d, J =
11.9 Hz, 1H, Hp); 4.28 (d, J = 11.9 Hz, 1H, Hq); 1.23 (s, 15H,
C5Me5).
Acknowledgment. Financial support from the Na-
tional Science Foundation of China (20721063, 20771028,
21001029), the Shanghai Leading Academic Discipline
Project (B108), the Shanghai Municipal Natural Science
Foundation (10ZR1404000), the National Basic Research
Program of China (2009CB825300), and the Shanghai Science
and Technology Committee (08dj1400100) is gratefully
acknowledged.
Supporting Information Available: UV/vis absorbance spec-
tra, luminescence emission spectra, and crystallographic data
for 2b, 4, 5, 6, 7, and 8 are available free of charge via the Internet
at http://pubs.acs.org.
Preparation of 8. A mixture of [Cp*RhCl2]2 (32 mg, 0.05
mmol), NaOAc (25 mg, 0.3 mmol), 3 (36 mg, 0.1 mmol), and
DMAD (14 mg, 0.1 mmol) was stirred at 80 °C in 20 mL of 1,2-
dichloroethane (DCE) for 8 h. The mixture was filtered through
Celite and evaporated to afford a purple solid, which was
washed by hexane three times and further purified by silica gel
column chromatography to afford purple compound 8 (46 mg,
93%). Anal. Calcd for C33H21NO4: C 79.99, H 4.27, N 2.83.
Found: C 79.92, H 4.28, N 2.46. 1H NMR (400 MHz, CDCl3,
ppm): δ 9.63 (d, 1H); 8.55 (s, 1H); 8.12-8.24 (m, 6H); 8.00 (m,
(15) Sheldrick, G. M. SHELXL-97, Program for the Refinement of
€
€
Crystal Structures; Universitat Gottingen: Germany, 1997.
(16) Sheldrick, G. M. SADABS (2.01), Bruker/Siemens Area Detec-
tor Absorption Correction Program; Bruker AXS: Madison, WI, USA,
1998.
(17) van der Sluis, P.; Spek, A. L. Acta Crystallogr. 1990, A46, 194.