Phosphorescence of iridium(III) complexes with 2-(2-pyridyl)-1,3,4- oxadiazoles

Article abstract of DOI:10.1016/j.ica.2012.07.026

Cationic bis-cyclometalated iridium(III) complexes [(C^N) ₂Ir(N^N)](PF₆) with 2-(2′-pyridyl)-5-R-1,3,4- oxadiazoles (N^N; R = 1-adamantyl, mesityl, N-diphenylamino) have a redox gap of 2.58-2.68 V and exhibit orange-red phosphorescence in argon-saturated dichloromethane solution with a maximum, quantum yield, and excited-state lifetime of 613-644 nm, 2-6%, and 90-280 ns.

Full text of DOI:10.1016/j.ica.2012.07.026

Inorganica Chimica Acta 394 (2013) 295–299
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Note
Phosphorescence of iridium(III) complexes with 2-(2-pyridyl)-1,3,4-oxadiazoles
⇑
⇑
Nail M. Shavaleev , Rosario Scopelliti, Michael Grätzel, Mohammad K. Nazeeruddin
Laboratory of Photonics and Interfaces, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
a r t i c l e i n f o
a b s t r a c t
Cationic bis-cyclometalated iridium(III) complexes [(C^N)2Ir(N^N)](PF6) with 2-(20-pyridyl)-5-R-1,3,4-
oxadiazoles (N^N; R = 1-adamantyl, mesityl, N-diphenylamino) have a redox gap of 2.58–2.68 V and
exhibit orange–red phosphorescence in argon-saturated dichloromethane solution with a maximum,
quantum yield, and excited-state lifetime of 613–644 nm, 2–6%, and 90–280 ns.
Ó 2012 Elsevier B.V. All rights reserved.
Article history:
Received 29 April 2012
Received in revised form 23 July 2012
Accepted 27 July 2012
Available online 3 August 2012
Keywords:
Iridium
1,3,4-Oxadiazole
Ligand
Complex
Cyclometalation
Phosphorescence
1. Introduction
on silica (Scheme 1). All new compounds were characterized by
elemental analysis, 1H, 13C, and 19F NMR spectroscopy, and mass-
Tuning of the photophysical properties of phosphorescent cat-
ionic iridium(III) complexes [(C^N)2Ir(N^N)]+ can be achieved by
changing the cyclometalating C^N and neutral N^N ligands [1–
10]. Here, we report phosphorescent cationic Ir(III) complexes with
alkyl, aryl, or diarylamino substituted 2-(20-pyridyl)-1,3,4-oxadiaz-
oles—a class of easy-to-make neutral N^N ligands rarely used in
coordination chemistry (Scheme 1) [11–16]. 1,3,4-Oxadiazole is
an electron-deficient heterocycle that finds application as an elec-
tron-transport group in organic electronics [17,18]. We note that
several research labs recently investigated neutral [19–21] and cat-
ionic [22,23] Ir(III) complexes with 1,3,4-oxadiazole-modified
cyclometalating ligands.
spectrometry.
Fig. 1 shows the X-ray structure of 3. The Ir(III) ion is in a dis-
torted octahedral [(C^N)2Ir(N^N)]+ coordination environment.
The two nitrogen atoms of the C^N ligands are in trans-position
to each other. The Ir–(C^N) bonds are shorter than the Ir–(N^N)
ones are (Table 1). The Ir–N (N^N) bond to oxadiazole is shorter
than that to pyridine by 0.032 Å (Table 1). The dihedral angles be-
tween the rings of the ligands are 6.22° (pyridyl and oxadiazole,
N^N) and 1.45° or 13.15° (phenyl and pyridine, C^N). The cations
of 3 do not participate in face-to-face
p–p stacking, and have the
minimum inter-metallic Irꢀ ꢀ ꢀIr distance 9.090(2) Å.
Redox potentials of 1–3 (relative to Fc+/Fc [26]) were measured
with cyclic voltammetry in acetonitrile and DMF and were found to
be solvent-independent (Fig. 2 and Fig. S1, Supporting informa-
tion). The complexes exhibit a reversible/quasi-reversible reduc-
tion of N^N ligand at ꢁ1.73 to ꢁ1.64 V; an irreversible oxidation
of Ir–phenyl fragment at 0.93–0.98 V; and the redox gap,
2. Results and discussion
Three new N^N ligands L1–L3 were prepared by reaction of 5-
(20-pyridyl)-1H-tetrazole with an acyl chloride in pyridine at reflux
(Scheme 1) [24]. We chose bulky 1-admantyl (L1) and mesityl (L2)
groups to reduce solid state interaction and to increase solubility of
the complexes. We chose a diphenylamino group (L3) because it
D
E = Eox ꢁ E1/2red, 2.58–2.68 V (Table 2). The observed variation of
reduction potentials,
3
(ꢁ1.73 V) < 1 (ꢁ1.68 V) < 2 (ꢁ1.64 V),
reflects the electron-donor strength of substituents in the N^N
ligand: diphenylamino (3) > 1-adamantyl (1) > mesityl (2).
1–3 exhibit more positive redox potentials than does the refer-
ence complex [(ppy)2Ir(2,20-bipyridine)](PF6), ꢁ1.77 and 0.84 V in
DMF [27] or ꢁ1.78 and 0.88 V in acetonitrile [28]; therefore, we
conclude that 1,3,4-oxadiazole is a stronger electron-acceptor
facilitates hole-transport in electroluminescent metal complexes
0
[25]. The reaction of L1–L3 with [(ppy)2Ir(
l
-Cl)]2 (ppy = N,C2 -2-
phenylpyridyl) gave three new Ir(III) complexes [(ppy)2Ir
(N^N)](PF6), 1–3, after purification by column chromatography
[17,18] and a weaker
Ligands L1–L3 are white solids; their electronic absorption
spectra exhibit bands at k < 375 nm that are enhanced and
r-electron-donor than is the pyridine.
⇑
Corresponding authors. Tel.: +41 21 693 6124; fax: +41 21 693 4111.
E-mail addresses: nail.shavaleev@epfl.ch (N.M. Shavaleev), mdkhaja.
nazeeruddin@epfl.ch (M.K. Nazeeruddin).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.07.026

296
N.M. Shavaleev et al. / Inorganica Chimica Acta 394 (2013) 295–299
O
N
a
b
N
N
R
+
L1, L2, L3
1, 2, 3
N
H
N
N
Cl
N
O
N
O
O
N
N
N
N
N
N
N
L1
L2
L3
N
N
N
Ir
N
Ir
N
N
N
N
N
N
O
O
O
C
C
C
C
C
Ir
C
N
N
N
N
N
N
PF6
PF6
PF6
1
2
3
Scheme 1. Synthesis of new ligands and Ir(III) complexes: (a) pyridine, under argon, reflux; (b) [(C^N)2Ir(
l-Cl)]2, under argon, 40 °C, dichloromethane/methanol, KPF6.
3
2
I
1
-2
-1
0
1
Fig. 1. Structure of 3 (CCDC 878933; 50% probability ellipsoids; H atoms and PF6
anion are omitted; ORTEP). Heteroatoms are shown as octant ellipsoids: Ir and N,
black; O, clear.
E/V vs Fc+/Fc in ACN
Fig. 2. Cyclic voltammograms of 1–3 in acetonitrile (glassy carbon electrode, 0.1 M
NBu4PF6, 100 mV/s). The unit on the vertical axis is 10
shown in the Supporting information.
lA. CVs of 1–3 in DMF are
Table 1
Bond lengths (Å) in 3a.
C^N
Ir–C
N^N
Table 2
b
Redox propertiesa.
Ir–N
Ir–N(py)b
Ir–N(oda)
2.163(5)
2.000(5)
2.022(6)
2.040(6)
2.064(5)
2.195(5)
Complex
Solvent
E1/2red/Vb
E
ox/Vc
D
E/Vd
1
DMF
ACN
DMF
ACN
DMF
ACN
ꢁ1.68 (98)e
ꢁ1.68 (78)
ꢁ1.64 (88)
ꢁ1.64 (78)
ꢁ1.73 (83)
ꢁ1.73 (83)
0.96
0.98
0.94
0.98
0.93
0.95
2.64
2.66
2.58
2.62
2.66
2.68
a
Each row corresponds to one ligand in the complex.
N(py) and N(oda) are nitrogen atoms of pyridine and 1,3,4-oxadiazole,
b
2
3
respectively.
a
In acetonitrile (ACN) or DMF. Relative to Fc+/Fc. Error: 50 mV. On glassy carbon
red-shifted when 1-adamantyl group in L1 is replaced with
aromatic (mesityl or diphenylamino) and charge-transfer (diphen-
ylamino-to-oxadiazole) chromophores in L2 and L3 (Fig. 3 and
Table 3).
working electrode, with 0.1 M (NBu4)PF6, at scan rate 100 mV/s. The anodic/
cathodic peak separation for the standard, Fc+/Fc couple, was 78–88 mV.
b
Reversible process (unless stated otherwise). The anodic/cathodic peak sepa-
ration is given in brackets.
c
Irreversible process. The return wave was observed in acetonitrile with anodic/
The complexes are yellow (1) or orange (2, 3) solids; their
electronic spectra in dichloromethane (Fig. 4, Table 3, and Fig. S2,
Supporting information) display an (Ir–phenyl)-to-(N^N) charge
transfer transition at k > 450 nm with molar absorption coefficients
cathodic peak separation of more than 150 mV at 100 mV/s. The oxidation peak
potential is reported.
d
e
red
D
E = Eox ꢁ E1/2
.
Quasi-reversible process; the anodic/cathodic peak separation is given in
(e
) of less than 103 Mꢁ1 cmꢁ1 [5]. The charge-transfer (MLCT, ILCT)
brackets.

N.M. Shavaleev et al. / Inorganica Chimica Acta 394 (2013) 295–299
297
18
16
14
12
10
8
3
2
6
4
ε
2
0
L1
L2
L3
350
1
250
275
300
325
375
500 550 600 650 700 750 800
Wavelength/nm
Wavelength/nm
Fig. 3. Absorption spectra of ligands L1 (2.67 ꢂ 10ꢁ4 M), L2 (3.51 ꢂ 10ꢁ4 M), and L3
(1.92 ꢂ 10ꢁ4 M) in dichloromethane.
Fig. 5. Corrected and normalized emission spectra of 1–3 at 10ꢁ5 M in argon-
saturated dichloromethane at room temperature (kexc = 350 nm;
Dkem = 1 nm).
Table 3
UV–Vis absorption maximaa.
Table 4
Photophysical propertiesa.
kabs/nm (e )
/103 Mꢁ1 cmꢁ1
Complex
kem/nm
U
/%
s
/ns
srad/ls
L1
L2
L3
1
2
3
278 (11), 289 (7.2, sh)
281 (16)
314 (17)
269 (46), 359 (7.9), 376 (8.0), 468 (0.8)
253 (48), 264 (47), 376 (8.3), 468 (0.8)
254 (55), 375 (13, sh), 466 (0.9, sh)
1
2
3
627
644
613
4
2
6
170
90
280
4
5
5
In argon-saturated dichloromethane at 10ꢁ5 M at room temperature. Estimated
errors: 2 nm for kem
a
; 20% for U and srad; 10 ns for s.
a
In dichloromethane at room temperature, 250–
800 nm. Errors: 2 nm for kabs 5% for
;
e.
threefold drop in
U from 3 to 2 (Table 4), because the contribution
of non-radiative processes to the excited state decay increases
when the emission energy of Ir(III) complex decreases [5].
The emission maxima of 1–3 are red-shifted and the quantum
yields are quenched when compared with those of the reference
[(ppy)2Ir(2,20-bipyridine)](PF6), 585 nm and 14% in acetonitrile
[27].
and ligand
p–
p⁄ transitions of 1–3 are observed at 350–450 nm
(e
< 13 ꢂ 103 Mꢁ1 cmꢁ1
)
and below 350 nm
(
e
< 55 ꢂ 103 Mꢁ1
cmꢁ1), respectively.
Complexes 1–3 in argon-saturated dichloromethane solution
exhibit orange–red phosphorescence with a maximum, quantum
yield (U), and excited-state lifetime (s) of 613–644 nm, 2–6%,
and 90–280 ns (Fig. 5 and Table 4). The excitation spectra of 1–3
match the absorption spectra (Fig. S3, Supporting information).
The luminescence decays are single exponential functions suggest-
ing the presence of one emissive center in solution (Fig. S4,
Supporting information).
The broad emission spectra, the relatively short calculated radi-
ative lifetimes (srad = s/U < 5 ls), and a direct correlation between
In conclusion, neutral 2-(20-pyridyl)-1,3,4-oxadiazole ligands,
which can be modified in a facile way with functional groups, give
phosphorescent cationic bis-cyclometalated Ir(III) complexes. Fur-
ther tuning of the redox and photophysical properties of these
complexes can be achieved by variation of the cyclometalating li-
gands. We expect 2-(20-pyridyl)-1,3,4-oxadiazoles to gain wider
application in coordination chemistry.
the emission energy and the electrochemical gap suggest that 1–3
emit from an [(Ir–phenyl)-to-(N^N)] charge-transfer excited state
[1,5]. The excited-state deactivation in 1–3 is dominated by
3. Experimental
The following data are provided in the Supporting information:
experimental techniques; synthesis of [(ppy)2Ir(l-Cl)]2; crystallo-
non-radiative processes, hence
U
6 6% (Table 4). We observe a
graphic data (Table S1); cyclic voltammograms (Fig. S1); absorp-
tion spectra (Fig. S2); excitation spectra (Fig. S3); luminescence
decays (Fig. S4); 1H, 13C, and 19F NMR spectra.
Purification, crystal growth, and handling of all compounds
were carried out under air. All products were stored in the dark.
Chemicals from commercial suppliers were used without purifica-
tion. Chromatography was performed on a column with an i.d. of
30 mm on silica gel 60 (Fluka, Nr 60752). The progress of reactions
and the elution of products were followed on TLC plates (silica gel
60 F254 on aluminum sheets, Merck).
50
40
30
20
2
ε
x10
10
3.1. Synthesis of the ligands
0
250 300 350 400 450 500 550 600
Wavelength/nm
The structures of L1–L3 are shown in Scheme 1. The reactions
were performed under argon. 5-(20-Pyridyl)-1H-tetrazole (AlfaAe-
sar) was dissolved in pyridine (99.5%, Extra Dry over Molecular
Sieves, AcroSeal, Acros). The required acyl chloride was added.
Fig. 4. Absorption spectrum of 2 (6.94 ꢂ 10ꢁ5 M) in dichloromethane. Additional
absorption spectra are shown in the Supporting information.

298
N.M. Shavaleev et al. / Inorganica Chimica Acta 394 (2013) 295–299
The reaction mixture was stirred at reflux overnight to give pale
yellow (L1), orange (L2), or dark red (L3) solution. It was cooled
to RT. Further details for the work-up and purification are provided
below.
hexane. White solid: 839 mg (2.67 mmol, 90%). Anal. Calc. for
19H14N4O (MW 314.34): C, 72.60; H, 4.49; N, 17.82. Found: C,
C
72.66; H, 4.54; N, 17.54%. 1H NMR (400 MHz, [D6]dmso):
d = 8.66–8.62 (m, 1H), 8.03–7.94 (m, 2H), 7.55–7.51 (m, 1H),
7.50–7.44 (m, 4H), 7.43–7.38 (m, 4H), 7.35–7.29 (m, 2H) ppm.
13C NMR (100 MHz, CD2Cl2): d = 163.34, 159.67, 150.20, 144.03,
142.58, 137.16, 129.79, 126.69, 125.64, 125.24, 122.19 ppm. ESI+
TOF MS: m/z 314 (M+, 70%).
3.1.1. Ligand L1
The reaction was performed with 5-(20-pyridyl)-1H-tetrazole
(500 mg, 3.40 mmol) and 1-adamantanecarboxylic acid chloride
(675 mg, 3.40 mmol, Acros) in pyridine (3.5 mL). The reaction mix-
ture was extracted with ether/H2O. The organic layer was washed
with water (to remove pyridine) and evaporated. Purification by
column chromatography was performed on silica (10 g). Elution
with CH2Cl2 removed the impurities. Elution with 0.5% of CH3OH
in CH2Cl2 recovered the product. It was re-dissolved in ether, and
hexane (20 mL) was added. The ether was rotor-evaporated to
leave a suspension of the product in hexane. The suspension was
cooled to ꢁ15 °C overnight and filtered. The product was washed
with cold hexane. The product purified in this way contained
10% of 1-adamantanecarboxylic acid (detected by 1H and 13C
NMR). To remove the acid, the product was sonicated in saturated
aqueous solution of Na2CO3 for 10 min and extracted with ether.
The organic layer was washed with saturated aqueous solution of
Na2CO3 and water. It was evaporated, and the extraction with
Na2CO3 (aq. sat.) and ether was repeated one more time. White so-
lid: 477 mg (1.70 mmol, 50%). Anal. Calc. for C17H19N3O (MW
281.35): C, 72.57; H, 6.81; N, 14.94. Found: C, 72.54; H, 6.87; N,
14.74%. 1H NMR (400 MHz, [D6]dmso): d = 8.79–8.74 (m, 1H),
8.19–8.13 (m, 1H), 8.03 (td, J = 8.0, 1.6 Hz, 1H), 7.62 (ddd, J = 7.6,
4.8, 1.2 Hz, 1H), 2.10–2.04 (m, br, 9H), 1.77 (br, 6H) ppm. 13C
NMR (100 MHz, CD2Cl2): d = 173.68, 163.90, 150.34, 144.25,
137.28, 125.72, 123.00, 40.12, 36.44, 34.71, 28.13 ppm. GC–EI+
MS: m/z 281 (M+, 100%).
3.2. Synthesis of the complexes
The structures of 1–3 are shown in Scheme 1. The reactions
were performed under argon. The solvents were deoxygenated
by bubbling with Ar, but they were not dried. [(ppy)2Ir(l-Cl)]2
(100 mg, 0.093 mmol; Supporting information) and N^N ligand
(L1, 56 mg; L2, 53 mg; L3, 60 mg; 0.19–0.20 mmol, small excess)
in CH2Cl2/CH3OH (20/4 mL) were stirred overnight at 40 °C to give
orange or red solution. It was evaporated. The residue was purified
by column chromatography (silica, 15 g). Elution with 2.0–4.0%
CH3OH in CH2Cl2 removed the impurities. Elution with 4.0–5.0%
CH3OH in CH2Cl2 recovered the product as yellow or orange frac-
tions (these were followed by green/yellow emissive impurities).
The desired fractions were evaporated. The product was dissolved
in CH3OH (3 mL), and added drop-wise to a stirred aqueous solu-
tion of KPF6 (390–730 mg, 2.12–3.97 mmol, in 25 mL of water,
large excess; Alfa Aesar) in order to convert the complex to the
hexafluorophosphate salt. The resulting suspension was stirred
for 30 min and filtered. The complex was washed with water, hex-
ane, and ether. 1–3 in dichloromethane solution and 2 and 3 in
powder exhibit orange–red phosphorescence. 1 exhibits yellow
phosphorescence in powder.
3.2.1. Complex 1
3.1.2. Ligand L2
Yellow solid: 70 mg (0.076 mmol, 41%). Anal. Calc. for
The reaction was performed with 5-(20-pyridyl)-1H-tetrazole
(730 mg, 4.96 mmol) and 2,4,6-trimethylbenzoyl chloride
(906 mg, 0.83 mL, 4.96 mmol, AlfaAesar) in pyridine (3.5 mL). The
reaction mixture was diluted with water (50 mL) to give suspen-
sion. It was stirred for 10 min. The precipitate of the crude product
was filtered, washed with water, and extracted with ether/H2O.
The organic layer was washed with water and evaporated. Purifica-
tion by column chromatography was performed on silica (15 g).
Elution with CH2Cl2 removed pale yellow impurity. Elution with
0.5% CH3OH in CH2Cl2 recovered the product. White solid: 1.10 g
(4.15 mmol, 84%). Anal. Calc. for C16H15N3O (MW 265.31): C,
72.43; H, 5.70; N, 15.84. Found: C, 72.24; H, 5.74; N, 15.53%. 1H
NMR (400 MHz, [D6]dmso): d = 8.79 (dd, J = 4.8, 0.8 Hz, 1H), 8.24
(dd, J = 8.0, 0.8 Hz, 1H), 8.12–8.04 (m, 1H), 7.69–7.62 (m, 1H),
7.09 (s, 2H), 2.33 (s, 3H), 2.25 (s, 6H) ppm. 13C NMR (100 MHz,
CD2Cl2): d = 164.96, 164.51, 150.52, 144.09, 141.48, 138.98,
137.39, 129.06, 125.98, 123.13, 121.19, 21.26, 20.44 ppm. GC–EI+
MS: m/z 265 (M+, 100%).
C39H35F6IrN5OP (MW 926.91): C, 50.54; H, 3.81; N, 7.56. Found:
C, 50.78; H, 3.92; N, 7.55%. 1H NMR (400 MHz, CD2Cl2): d = 8.37
(d, J = 7.6 Hz, 1H), 8.25 (t, J = 7.6 Hz, 1H), 8.03–7.95 (m, 3H),
7.90–7.82 (m, 3H), 7.74 (d, J = 8.0 Hz, 2H), 7.64 (dd, J = 7.6, 5.2 Hz,
1H), 7.44 (d, J = 5.2 Hz, 1H), 7.18–7.04 (m, 4H), 6.97 (td, J = 7.6,
1.6 Hz, 1H), 6.92 (td, J = 7.6, 1.2 Hz, 1H), 6.31–6.22 (m, 2H), 2.15
(s, br, 9H), 1.90–1.77 (m, 6H) ppm. 13C NMR (100 MHz, CD2Cl2):
all of the expected signals in the aromatic (29C) and aliphatic
(4C) regions were observed, d = 176.88, 168.42, 167.79, 167.15,
151.66, 150.08, 149.01, 146.41, 144.15, 143.96, 143.92, 141.05,
140.25, 138.50, 138.40, 131.80, 131.42, 130.73, 130.48, 129.97,
125.80, 124.88, 124.47, 123.81, 123.48, 123.28, 122.69, 119.87,
119.73, 39.39, 35.83, 35.58, 27.60 ppm. 19F NMR (376 MHz,
CD2Cl2): d = ꢁ73.36 (d, JP–F = 710 Hz, PF6) ppm. ESI+ TOF MS: m/z
782.24 ({MꢁPF6}+, 100%).
3.2.2. Complex 2
Orange solid: 103 mg (0.113 mmol, 61%). Anal. Calc. for
C38H31F6IrN5OP (MW 910.87): C, 50.11; H, 3.43; N, 7.69. Found:
3.1.3. Ligand L3
C, 50.35; H, 3.48; N, 7.64%. 1H NMR (400 MHz, CD2Cl2): d = 8.39
(d, J = 7.6 Hz, 1H), 8.27 (t, J = 7.6 Hz, 1H), 8.07–7.97 (m, 4H),
7.92–7.83 (m, 2H), 7.79 (dd, J = 8.0, 1.2 Hz, 1H), 7.73 (dd, J = 7.6,
1.2 Hz, 1H), 7.71–7.64 (m, 1H), 7.51 (d, J = 5.2 Hz, 1H), 7.19–7.02
(m, 4H), 7.05 (s, 2H), 7.00 (td, J = 7.6, 1.2 Hz, 1H), 6.92 (td, J = 7.6,
1.2 Hz, 1H), 6.39 (dd, J = 7.6, 0.8 Hz, 1H), 6.32 (dd, J = 8.0, 0.8 Hz,
1H), 2.37 (s, 3H), 2.23 (s, 6H) ppm. 13C NMR (100 MHz, CD2Cl2):
only 31C out of the expected 33C signals were observed in the aro-
matic region; the expected 2C signals were observed in the ali-
phatic region; d = 169.05, 168.05, 167.80, 167.28, 151.79, 150.02,
148.81, 146.72, 143.98, 143.85, 143.25, 140.87, 140.35, 139.21,
138.57, 138.51, 131.82, 130.74, 130.69, 130.03, 129.35, 126.13,
124.96, 124.46, 123.78, 123.56, 123.30, 122.80, 119.97, 119.63,
The reaction was performed with 5-(20-pyridyl)-1H-tetrazole
(437 mg, 2.97 mmol) and diphenylcarbamoyl chloride (693 mg,
2.99 mmol, AlfaAesar) in pyridine (3 mL). The reaction mixture
on cooling to RT gave suspension. It was diluted with solution of
Na2CO3 (sat. aq.) and extracted with CH2Cl2. The organic layer
was washed with water and evaporated. Purification by column
chromatography was performed on silica (15 g). Elution with
CH2Cl2 removed yellow impurity. Elution with 0.5–1.0% CH3OH
in CH2Cl2 recovered the product. It was re-dissolved in CH2Cl2,
and ethanol (20 mL) was added. Dichloromethane was rotor-
evaporated to leave a suspension of the product in ethanol. It
was cooled to room temperature, filtered, and washed with

N.M. Shavaleev et al. / Inorganica Chimica Acta 394 (2013) 295–299
299
118.12, 21.15 (CH3), 20.24 (CH3) ppm. 19F NMR (376 MHz, CD2Cl2):
References
d = ꢁ73.33 (d, JP–F = 710 Hz, PF6) ppm. ESI+ TOF MS: m/z 766.20
({MꢁPF6}+, 100%).
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3.2.3. Complex 3
Orange solid: 124 mg (0.129 mmol, 69%). Anal. Calc. for
C
41H30F6IrN6OP (MW 959.90): C, 51.30; H, 3.15; N, 8.76. Found:
C, 51.26; H, 3.16; N, 8.58%. 1H NMR (400 MHz, CD2Cl2): d = 8.16
(d, J = 5.2 Hz, 1H), 8.08 (t, J = 7.2 Hz, 1H), 8.03–7.92 (m, 3H),
7.92–7.84 (m, 3H), 7.76–7.68 (m, 2H), 7.54–7.43 (m, 6H), 7.43–
7.35 (m, 6H), 7.27–7.20 (m, 1H), 7.15–7.07 (m, 2H), 7.02 (td,
J = 7.6, 0.8 Hz, 1H), 6.96 (td, J = 7.6, 1.6 Hz, 1H), 6.88 (td, J = 7.6,
1.2 Hz, 1H), 6.28–6.22 (m, 2H) ppm. 13C NMR (100 MHz, CD2Cl2):
only 32C out of the expected 33C signals were observed in the aro-
matic region, d = 167.87, 166.96, 164.14, 162.94, 151.36, 150.60,
149.00, 146.60, 144.42, 144.02, 143.73, 141.28, 140.68, 139.84,
138.41, 138.34, 131.71, 131.43, 130.61, 129.94, 129.15, 128.02,
125.93, 124.79, 124.40, 124.07, 123.96, 123.43, 123.16, 122.63,
119.72, 119.67 ppm. 19F NMR (376 MHz, CD2Cl2): d = ꢁ73.33 (d,
JP–F = 710 Hz, PF6) ppm. ESI+ TOF MS: m/z 815.2 ({MꢁPF6}+, 100%).
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Acknowledgment
European Union (CELLO, STRP 248043; http://www.cello-
project.eu/).
Appendix A. Supplementary material
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CCDC 878933 contains the supplementary crystallographic data
for complex 3. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at http://dx.doi.org/10.1016/
j.ica.2012.07.026.