Synthesis and Optoelectronic Properties of Cationic Iridium(III) Complexes with o-Carborane-Based 2-Phenyl Benzothiazole Ligands

Article abstract of DOI:10.1021/acs.inorgchem.0c03625

A series of cationic cyclometalated iridium(III) complexes with o-carborane cage on the main ligand of 2-phenylbenzothiazole were synthesized. The prepared iridium complexes (C1-C6) were fully characterized by UV-vis, NMR, and FT-IR spectra. The exact molecular structure of complex C1 was further studied by single crystal X-ray diffraction analysis. The different substitution position of o-carborane on the 2-phenylbenzothiazole ring lead to obvious differences in the emission properties of the synthesized complexes. The o-carboranyl unit results in a bathochromic shift of 10 nm in the fluorescence emission spectrum of C2. In addition, the presence of an o-carborane fragment promoted the strong fluorescence intensity of C1 and C4, which can be used as a tool to effectively boost the intensity of fluorescence properties. The emission fluorescent behavior of iridium(III) complexes can be facilely tuned by structural variations in the main ligands of these materials.

Full text of DOI:10.1021/acs.inorgchem.0c03625

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Synthesis and Optoelectronic Properties of Cationic Iridium(III)
Complexes with o‑Carborane-Based 2‑Phenyl Benzothiazole Ligands
Zi-Jian Yao,* Yong-Xu Jin, Wei Deng, and Zhen-Jiang Liu*
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ABSTRACT: A series of cationic cyclometalated iridium(III)
complexes with o-carborane cage on the main ligand of 2-
phenylbenzothiazole were synthesized. The prepared iridium
complexes (C1−C6) were fully characterized by UV−vis, NMR,
and FT-IR spectra. The exact molecular structure of complex C1
was further studied by single crystal X-ray diffraction analysis. The
different substitution position of o-carborane on the 2-phenyl-
benzothiazole ring lead to obvious differences in the emission
properties of the synthesized complexes. The o-carboranyl unit
results in a bathochromic shift of 10 nm in the fluorescence
emission spectrum of C2. In addition, the presence of an o-carborane fragment promoted the strong fluorescence intensity of C1 and
C4, which can be used as a tool to effectively boost the intensity of fluorescence properties. The emission fluorescent behavior of
iridium(III) complexes can be facilely tuned by structural variations in the main ligands of these materials.
functionalization on the 2-phenylbenzothiazole ligand ring.
Herein, we prompted to synthesize a new carborane-modified
C^N ligand (2-phenylbenzothiazole ligand) and tried to
introduce the carborane fragment into different positions of
2-phenylbenzothiazole ligands to achieve a new type of
iridium(III) complexes (C1−C6). 2,2-Bipyridine and phenan-
throline are used as the auxiliary ligands, and the structure and
photoelectric properties of the prepared complexes are fully
characterized. The experimental results show that introduction
of a rigid and large carboryl group into the 2-phenyl-
benzothiazole ligand can improve the quantum efficiency of
the generated cationic C,N-chelate iridium(III) complex.
INTRODUCTION
■
Over the past several years, the development and application of
the iridium(III) cyclometalated complexes, as luminescent
materials, have attracted the interest of many researchers.1−3
Iridium(III) coordination compounds have been proven to
exhibit good light and thermal stability, a wide range of tunable
emission colors, and high quantum yields.4−6 They have been
thoroughly used in organic light emitting diodes (OLEDs),7
luminescent probes,8 cell imaging,9 and chemosensing.10 The
structure of ligands in iridium(III) complexes strongly affect
their photophysical properties.11,12 Therefore, the electronic
properties and performance of iridium(III) complexes are
directly affected by the nature, structure, and position of the
introduced ligand substituents.13,14 Thus, the design and
construction of new ligands with unique structures are
attractive.
o-Carborane (1,2-C2B10H12) has a three-dimensional geo-
metric cage-like rigid structure with a large volume group,15−18
providing a unique steric hindrance,19−24 hindering intermo-
lecular interactions, reducing self-quenching, and potential
concentration quenching25 with high chemical and thermal
stability.26−30 The strong electron-withdrawing behavior of the
cage in combination with its steric effects strongly affects the
photoluminescence (PL) characteristics of this compound.31
Therefore, chemical functionalization of carborane has been
the focus of intense research by introducing new carboranyl
groups into the ligands of cyclometalated iridium(III)
complexes.32−42
RESULTS AND DISCUSSION
■
Synthesis and Characterization of Cationic Iridium
Complexes with Functionalized o-Carobrane Ligands.
The o-carborane-modified 2-phenylbenzothiazole ligands
(L1−L3) were prepared through reported synthetic methods
from B10H10(Et4N)2 (see SI), as cheap, commercially available,
stable, and nontoxic starting materials in a good yield.44,45 The
o-carborane-functionalized iridium(III) complexes (C1−C6)
were prepared through the reaction of the o-carborane-
modified 2-phenylbenzothiazole ligands with iridium chlorides
Received: December 11, 2020
Published: January 22, 2021
Up to now, several cyclometalated iridium(III) complexes
with the 2-phenylbenzothiazole ligand were reported.43
However, no research is performed to introduce o-carborane
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Scheme 1. Synthetic Routes of Iridium(III) Complexes C1−C6
to give the dimeric iridium intermediate [(Cb-btz)2Ir(μ-
Cl)]2(Cb = o-carborane, btz = 2-phenyl benzothiazole). The
prepared dimer was then reacted with the corresponding N^N
ligands to yield the corresponding hexafluorophosphate salts
after the addition of KPF6 (Scheme 1). The detailed synthesis
method of these compounds is described in the Experimental
Section.46
crystallographic data in Table S1). The iridium center of C1
adopted a distorted octahedral geometry. The introduction of
o-carborane increased the molecular structure volume, and the
generated large cage occupied a relatively large space. It is
believed that inhibition of metal interactions can effectively
enhance the optical physical properties of the complex, as
previously reported in analogous iridium(III) complexes with
the cyclometalated C^N ligands.48,49
Photophysical Properties of Cationic Cyclometalated
Iridium Complexes. The UV−vis absorption and photo-
luminescence measurements were implemented in water- and
oxygen-free CH2Cl2 solution for all iridium complexes (C1−
C6), and their detailed photophysical data were summarized in
Table 1. All synthesized complexes exhibited similar absorption
The generation of o-carborane functionalized iridium(III)
1
complexes C1−C6 was supported by H NMR and FT-IR
spectroscopic techniques. The 1H NMR spectra of these
iridium complexes exhibited one proton signal at δ 5.00 ppm,
which is the typical signal of o-carboranyl C−H protons.
Meanwhile, a broad B−H proton signal in the high-field range
of δ 3.00−1.00 ppm for C1−C6 also suggested the presence of
an o-carborane cage, as confirmed by similar previous
reports.47 Observation of a characteristic absorption band at
about 2570 cm−1 in the FT-IR spectra of C1−C6 further
confirmed the presence of an o-carborane fragment in these
complexes (see Figure S1).
Table 1. Photophysical and Electrochemical Data of o-
Carborane-Functionalized Iridium(III) Complexes C1−C6
a
a
b
c
ox
λem
Eonset
Eg
HOMO/LUMO
(eV)
a
complex
(nm)
ΦPL
(eV)
(eV)
C1
C2
C3
C4
C5
C6
527.0
535.0
525.0
528.0
534.0
526.0
0.17
0.14
0.19
0.21
0.21
0.26
−0.70
−0.77
−0.72
−0.76
−0.72
2.54
2.62
2.63
2.56
2.63
2.57
−4.10/−1.56
−4.03/−1.41
−4.08/−1.45
−4.04/−1.48
−4.08/−1.45
−4.02/−1.45
In order to clearly elucidate the chemical structure of the
target complexes, a suitable single crystal of complex C1 was
prepared from the saturated Et2O solution by slow evaporation
of the DCM solution. The molecular structure of C1 was
determined via X-ray diffraction analysis (Figure 1 and detailed
−0.78
a
b
In degassed CH2Cl2 at 298 K. In degassed CH3CN at 298 K.
c
HOMO (eV) = −e(Eonsetox + 4.8), Eg = 1240/λ, LUMO (eV) = Eg +
HOMO.
curves. The main strong absorption peaks below 360 nm were
principally ascribed to the π−π* transitions in the carborane-
based ligands. Additionally, weak absorption peaks in the range
of 360−480 nm were assigned to the ligand-to-ligand (LLCT)
and metal-to-ligand (MLCT) charge transfers, which are
referenced in similar previous reports describing photophysical
characteristics of iridium(III) complexes (Figure 2).49
As indicated in Figure 3, C1 and C4, C2 and C5, and C3
and C6 have similar largest emission peaks (λmax) at 528, 526,
and 534 nm, respectively. The emission profiles of the
photoluminescent iridium complexes C2 and C5 were red-
shifted (λmax 535 and 534 nm, respectively) compared to that
of the other complexes, maybe due to the substitution position
of the relatively strong electron-withdrawing carborane in the
L2 ligand. This observation demonstrated that changing the o-
carboranylation position on the ancillary ligand can obviously
tune the phosphorescence efficiency of the cationic cyclo-
metalated iridium(III) complexes.50
−
Figure 1. X-ray crystal structure of C1. All hydrogen atoms and PF6
anions are omitted for clarity. Selected bond lengths (Å) and angles
(deg) for C1: Ir(1)−C(1), 2.018(2); Ir(1)−N(1), 2.061(2); Ir(1)−
N(2), 2.145(2); N(1)−C(7), 1.322(3); N(1)−C(13), 1.397(3);
N(2)−C(20), 1.332(3); N(2)−C(16), 1.363(3); C(1)−C(2),
1.398(4); C(1)−C(6), 1.415(4); C(10)−C(14), 1.505(3); C(14)−
C(15), 1.642(4); C(1)−Ir(1)−N(1), 79.93(9); C(7)−N(1)−C(13),
111.3(2); C(2)−C(1)−C(6), 116.4(2); C(20)−N(2)−C(16),
118.0(2); C(9)−C(10)−C(11), 120.1(2); C(10)−C(14)−C(15),
119.1(2).
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Figure 2. UV−vis absorption spectra of o-carborane-functionalized iridium complexes C1−C6 in the degassed CH2Cl2 (5.0 × 10−5 M, 298 K).
Figure 3. Emission spectra of o-carborane-functionalized iridium complexes C1−C6 in the degassed CH2Cl2 (5.0 × 10−5 M, λem 365 nm, 298 K).
Figure 4 shows the emission spectra of C2 and C4 in various
solvents to study the solvent effects, as is disclosed in recent
papers. Obviously, the intensity of fluorescence emission was
changed with solvent polarity; however, C2 and C4 complexes
displayed little discoloration. The MLCT transitions in
iridium(III) complexes have shown that the solvatochromic
effects would be related to the molecular dipole moments.
Therefore, C2 and C4 complexes were less affected by the
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Figure 4. Emission spectra of C2 and C4 complexesin various degassed solvents: DCM, THF, CH3Cl, acetone, CH3CN, MeOH (1.0 × 10−5 M, λex
365 nm, 298 K).
Figure 5. Emission spectra of C2 and C4 complexes at different O2 concentrations (0 and 21%) in the degassed CH3OH at 298 K (2.5 × 10−5 M,
λex 365 nm).
polarity changes. The o-carborane fragment on the 2-
phenylbenzothiazole ligand induces a powerful electron-
withdrawing environment, which caused a small change in
the molecular dipole moment of these complexes.
Ensuring adequate oxygen is very important to diagnosis and
treatment evaluations. It is rather remarkable that the
fluorescence intensities of both C2 and C4 are very sensitive
to the changes of oxygen concentration from 0 to 21%, though
the emission color of these complexes remained relatively
stable (Figure 5). In the absence of O2, the light intensities of
C2 and C4 were brighter. This means that these complexes
have the potential to monitor a lower level of endocellular
oxygen concentration.
Electrochemical Properties of the Iridium Complexes.
The electrochemical properties of the cationic o-carborane-
based iridium(III) complexes were investigated by cyclic
voltammetry (CV) using n-Bu4NPF6 (0.1 M), as the
supporting electrolyte in the degassed CH3CN solution. All
Figure 6. Cyclic voltammograms of iridium(III) complexes C1−C6 at
a scan rate of 100 mV s−1.
complexes showed reversible oxidation waves with potentials
in the range of 0.4−0.8 V. CV curves are recorded in Figure 6,
and their redox potentials are summarized in Table 1.
Oxidation potentials are almost the same for all of the cationic
o-carborane-based cyclometalated iridium(III) complexes,
consistent with the energy gaps and emissive wavelengths.
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nitrogen and, then, filtered to remove the solvent. The insoluble
inorganic salt was washed with water and ether. Thereafter, the
resulting solid was achieved by the evaporation of solvent under
reduced pressure. Finally, the chlorine-bridged iridium dimer complex
precursor [(Cb-btz)2Ir(μ-Cl)]2 was attained. Then, the complex
precursor (0.5 mg, 0.27 mmol) was reacted with 1,10-phenanthroline
(0.107 g, 0.54 mmol) in THF (15 mL). Thereafter, the reaction
solution was stirred at 80 °C for 16 h under nitrogen and cooled to
room temperature, and KPF6 was added in 10-fold excess. This
mixture was stirred for 2 h, then, evaporated to dryness under reduced
pressure. The residue was chromatographed on silica gel with elution
by 1:3 PE/EA (v/v) to give C1 as an orange-red solid with 32% yield.
1H NMR (500 MHz, (CD3)2CO): δ 8.95 (d, J = 8.0 Hz, 1H), 8.63 (d,
J = 5.0 Hz, 1H), 8.46 (s, 1H), 8.38 (s, 1H), 8.14 (dd, J = 5.0 Hz, 2.5
Hz, 1H), 8.05 (d, J = 7.5 Hz, 1H), 7.22 (d, J = 9.0 Hz, 1H), 7.17 (t, J
= 7.5 Hz, 1H), 6.99 (t, J = 7.5 Hz, 1H), 6.55 (d, J = 7.5 Hz, 1H), 5.91
(d, J = 9.0 Hz, 1H), 5.04 (s, 1H, carborane-CH), 2.81−1.80 (br, 10H,
BH). 13C NMR (125 MHz, (CD3)2CO): 184.46, 152.04, 150.51,
150.09, 147.58, 140.31, 139.65, 133.47, 132.41, 131.45, 130.96,
128.60, 127.44, 127.30, 123.90, 123.56, 117.09, 75.93 (B−C), 61.15
(B−C). IR (KBr): υ 2570 cm−1 (B−H). Elemental analysis calcd (%)
for C42H44B20N4S2IrPF6: C 41.27, H 3.63, N 4.58. Found: C 41.35, H
3.69, N 4.62.
Synthesis of Iridium Complex C2. This complex was prepared
in a manner similar to that of C1. Then, a mixture of the
corresponding precursor complex (0.5 mg, 0.27 mmol) and 1,10-
phenanthroline (0.107 g, 0.54 mmol) was prepared, and KPF6 in THF
(15 mL) was added in 10-fold excess to this mixture to afford an
orange-red solid of C2 with 30% yield. 1H NMR (500 MHz,
(CD3)2CO): δ 8.97 (d, J = 8.0 Hz, 1H), 8.60 (d, J = 5.0 Hz, 1H), 8.39
(s, 1H), 8.21 (d, J = 8.0 Hz, 1H), 8.15 (m, 1H), 8.06 (d, J = 8.0 Hz,
1H), 7.43 (d, J = 8.0 Hz, 2H), 7.11 (d, J = 7.5 Hz, 1H), 6.69 (s, 1H),
6.12 (d, J = 8.5 Hz, 1H), 4.84 (s, 1H, carborane−CH), 2.86−1.47 (br,
10H, BH). 13C NMR (125 MHz, (CD3)2CO): 180.62, 152.08,
149.39, 149.14, 147.64, 142.52, 139.72, 139.53, 135.92, 133.08,
132.13, 131.56, 128.62, 128.44, 127.45, 126.66, 126.63, 124.23,
122.31, 117.75, 76.45 (B−C), 60.76 (B−C). IR (KBr): υ 2559 cm−1
(B−H). Elemental analysis calcd (%) for C42H44B20N4S2IrPF6: C
41.27, H 3.63, N 4.58, Found: C 41.39, H 3.66, N 4.67.
CONCLUSIONS
■
In summary, a series of particular emissive fluorescent
iridium(III) complexes containing o-carborane modified 2-
phenyl benzothiazole ligands has been prepared. The emission
spectra of the prepared iridium(III) complexes were
thoroughly affected by introducing o-carborane on different
positions of 2-phenyl benzothiazole and resulted in a
bathochromic shift of 10 nm. The fluorescence intensity of
the prepared complexes is also affected by the inclusion of o-
carborane at different positions of 2-phenyl benzothiazole.
Additionally, all iridium complexes showed reversible oxidation
waves with potentials in the range of 0.4−0.8 V. The design
and photophysical properties of o-carborane-functionalized
fluorescent materials will be deeply investigated in the near
future.
EXPERIMENTAL SECTION
■
General Data. All reactions were performed under an atmosphere
of nitrogen using standard Schlenk and glovebox techniques unless
otherwise noted. Chemicals were purchased from commercial sources
without further purification. All solvents were treated with a molecular
sieve to remove water. Toluene was freshly distilled on CaH2. 1H and
13C NMR spectra were recorded on a Bruker DMX-500 spectrometer.
UV−vis absorption spectra were attained using a UV 765
spectrophotometer by using a 1 cm path length quartz cuvette. FT-
IR spectra were measured with the Nicolet FT-IR spectrophotometer
by using KBr. Fluorescence measurements were carried out on a
Lengguang Technology F97 fluorescence spectrophotometer.
B10H12(Et2S)2 and intermediate compounds were synthesized by a
1
modified reported method (see Scheme S1). Some impurities in H
NMR spectra in the range of 0.80−1.70 ppm of the ligands and
iridium complexes are assigned to the solvent (petroleum ether) and
H2O peaks.
Synthesis of L1 (2-Phenyl-6-carboranylbenzothiazole). In a 100
mL Schlenk tube, a mixture of 6-ethynyl-2-phenyl-benzothiazole (1.3
g, 5.5 mmol) and the carborane precursor B10H12(Et2S)2 (2.2 g, 5.7
mmol) was mixed in dry toluene (25 mL). The mixture was heated to
120 °C for 72 h under a nitrogen atmosphere. After cooling to room
temperature, the reaction progress was monitored by TLC. Then, the
solvent was evaporated to dryness under reduced pressure, and the
residue was purified by silica gel column chromatography using PE/
EA 1:10 (v/v) as an eluent. Drying in a vacuum afforded L1 as a white
Synthesis of Iridium Complex C3. This complex was prepared
in a manner similar to that of C1. A mixture of the corresponding
precursor complex (0.5 mg, 0.27 mmol) and 1,10-phenanthroline
(0.107 g, 0.54 mmol) was prepared, and KPF6 in THF (15 mL) was
added in 10-fold excess to this mixture to afford an orange solid of C3
1
with 27% yield. H NMR (500 MHz, (CD3)2CO): δ 8.95 (d, J = 8.5
1
Hz, 1H), 8.63 (s, 1H), 8.36 (s, 1H), 8.26 (s, 1H), 8.10 (d, J = 8.0 Hz,
1H), 7.34 (t, J = 7.5 Hz, 1H), 7.24 (d, J = 8.0 Hz, 1H), 6.99 (t, J = 8.0
Hz, 1H), 6.63 (d, J = 6.0 Hz, 1H), 6.02 (d, J = 8.5 Hz, 1H), 5.23 (s,
1H, carborane−CH), 2.87−1.81 (br, 10H, BH). 13C NMR (125
MHz, (CD3)2CO): 180.77, 152.14, 151.80, 148.94, 147.48, 141.63,
139.79, 134.17, 131.83, 131.47, 131.02, 128.89, 128.58, 128.24,
127.46, 126.57, 125.09, 124.21, 117.46, 77.04 (B−C), 61.24 (B−C).
IR (KBr): υ 2570 cm−1 (B−H). Elemental analysis calcd (%) for
C42H44B20N4S2IrPF6: C 41.27, H 3.63, N 4.58. Found: C 41.21, H
3.70, N 4.67.
solid with 46% yield. H NMR (500 MHz, CDCl3): δ 8.08 (s, 3H),
7.98 (d, J = 8.5 Hz, 1H), 7.59 (d, J = 8.0 Hz, 1H), 7.53 (s, 3H), 4.04
(s, carborane-CH, 1H), 3.34−1.69 (br, 10H, BH).
Synthesis of L2 (2-(4-Carboborylphenyl) Benzothiazole). The
compound was prepared in a manner similar to the synthesis of L1
using 2-(4-ethynylphenyl) benzothiazole (1.3 g, 5.5 mmol) and the
carborane precursor B10H12 (Et2S)2(2.2 g, 5.7 mmol) in dry toluene
1
(25 mL). The white solid L2 was attained in 64% yield. H NMR
(500 MHz, CDCl3): δ 8.09 (d, J = 8.0 Hz, 1H), 8.05 (d, J = 8.5 Hz,
2H), 7.92 (d, J = 7.5 Hz, 1H), 7.60 (d, J = 7.5 Hz, 2H), 7.53 (td, J =
8.0 Hz, 1 Hz, 1H), 7.43 (td, J = 8.0 Hz, 1 Hz, 1H), 4.02 (s, carborane-
CH, 1H), 3.23−1.72 (br, 10H, BH).
Synthesis of L3 (2-(3-Carboborylphenyl) Benzothiazole). This
compound was prepared in a manner similar to the synthesis of L1
using 2-(3-ethynylphenyl) benzothiazole (1.3 g, 5.5 mmol) and the
carborane precursor B10H12 (Et2S)2 (2.2 g, 5.7 mmol) in dry toluene
Synthesis of Iridium Complex C4. This complex was prepared
in a manner similar to that of C1. A mixture of the corresponding
precursor complex (0.5 mg, 0.27 mmol) and 2,2′-bipyridine (0.084 g,
0.54 mmol) was prepared, and KPF6 in THF (15 mL) was added in
10-fold excess to this mixture to afford an orange-red solid of C4 with
1
29% yield. H NMR (500 MHz, (CD3)2CO): δ 8.84 (d, J = 8.0 Hz,
1
(25 mL). The light yellow solid L3 was attained in 42% yield. H
1H), 8.56 (s, 1H), 8.35 (t, J = 7.5 Hz, 1H), 8.27 (d, J = 5 Hz, 1H),
8.02 (d, J = 8.0 Hz, 1H), 7.80 (t, J = 6.5 Hz, 1H), 7.45 (dd, J = 9.0
Hz, 1.5 Hz, 1H), 7.15 (t, J = 7.5 Hz, 1H), 6.95 (t, J = 7.0 Hz, 1H),
6.44 (d, J = 7.5 Hz, 1H), 6.24 (d, J = 9.0 Hz, 1H), 5.16 (s, 1H,
carborane−CH), 3.01−1.63 (br, 10H, BH). 13C NMR (125 MHz,
(CD3)2CO): 184.32, 156.58, 151.32, 151.03, 150.04, 140.51, 140.06,
133.18, 132.68, 132.50, 131.13, 129.12, 127.57, 127.45, 124.84,
127.06, 123.47, 117.33, 76.01 (B−C), 61.24 (B−C). IR (KBr): υ
2569 cm−1 (B−H). Elemental analysis calcd (%) for
NMR (500 MHz, CDCl3): δ 8.24 (s, 1H), 8.10 (d, J = 8.0 Hz, 1H),
8.03 (d, J = 8.0 Hz, 1H), 7.93 (d, J = 8.0 Hz, 1H), 7.63 (d, J = 8.0 Hz,
1H), 7.53 (t, J = 7.0 Hz, 1H), 7.47 (t, J = 7.5 Hz, 1H), 7.43 (t, J = 7.5
Hz, 1H), 4.14 (s, carborane-CH, 1H), 3.01−1.80 (br, 10H, BH).
Synthesis of Iridium Complex C1. In a 100 mL Schlenk tube, a
mixture of L1 (0.8 g, 2.30 mmol) and IrCl3·3H2O (0.4 g, 1.14 mmol)
was dissolved in a mixed solvent including 2-ethoxyethanol (30 mL)
and H2O (10 mL). The mixture was stirred at 120 °C for 8 h under
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C40H44B20N4S2IrPF6: C 40.09, H 3.70, N 4.68. Found: C 40.16, H
3.61, N 4.77.
Substances, Shanghai Institute of Organic Chemistry, Chinese
Academy of Sciences, Shanghai 200032, China; orcid.org/
0000-0003-1833-1142; Phone: +86-21-60877231;
Email: zjyao@sit.edu.cn; Fax: +86-21-60873335
Zhen-Jiang Liu − School of Chemical and Environmental
Engineering, Shanghai Institute of Technology, Shanghai
201418, China; orcid.org/0000-0001-6850-9485;
Email: zjliu@sit.edu.cn
Synthesis of Iridium Complex C5. This complex was prepared
in a manner similar to that of C1. A mixture of the corresponding
precursor complex (0.5 mg, 0.27 mmol) and 2,2′-bipyridine (0.084 g,
0.54 mmol) was prepared, and KPF6 in THF (15 mL) was added in
10-fold excess to this mixture to afford an orange-red solid of C5 with
1
34% yield. H NMR (500 MHz, (CD3)2CO): δ 8.88 (d, J = 8.0 Hz,
1H), 8.36 (t, J = 8.0 Hz, 1H), 8.29 (d, J = 8.0 Hz, 1H), 8.21 (d, J = 5.0
Hz, 1H), 8.01 (d, J = 8.0 Hz, 1H), 7.79 (t, J = 8.0 Hz, 1H), 7.55 (t, J =
7.5 Hz, 1H), 7.39 (dd, J = 8.5 Hz, 1.5 Hz, 1H), 7.32 (t, J = 8.0 Hz,
1H), 6.56 (s, 1H), 6.45 (d, J = 8.5 Hz, 1H), 4.84 (s, 1H, carborane−
CH), 2.80−1.46 (br, 1H, BH). 13C NMR (125 MHz, (CD3)2CO):
180.47, 156.72, 151.26, 149.88, 149.10, 142.29, 140.53, 135.96,
132.77, 132.23, 129.11, 128.64, 126.59, 125.00, 124.36, 122.13,
117.98, 76.36 (B−C), 60.64 (B−C). IR (KBr): υ 2570 cm−1 (B−H).
Elemental analysis calcd (%) for C40H44B20N4S2IrPF6: C 40.09, H
3.70, N 4.68. Found: C 40.00, H 3.76, N 4.79.
Authors
Yong-Xu Jin − School of Chemical and Environmental
Engineering, Shanghai Institute of Technology, Shanghai
201418, China
Wei Deng − School of Chemical and Environmental
Engineering, Shanghai Institute of Technology, Shanghai
201418, China
Synthesis of Iridium Complex C6. This complex was prepared
in a manner similar to that of C1. A mixture of the corresponding
precursor complex (0.5 mg, 0.27 mmol) and 2,2′-bipyridine (0.084 g,
0.54 mmol) was prepared, and KPF6 in THF (15 mL) was added in
10-fold excess to this mixture to afford an orange-red solid of C6 with
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c03625
Notes
1
The authors declare no competing financial interest.
36% yield. H NMR (500 MHz, (CD3)2CO): δ 8.83 (d, J = 8.5 Hz,
1H), 8.33 (t, J = 7.5 Hz, 1H), 8.23 (d, J = 5.0 Hz, 1H), 8.21 (s, 1H),
8.20 (d, J = 5.0 Hz, 1H), 7.75 (t, J = 6.5 Hz, 1H), 7.49 (t, J = 7.5 Hz,
1H), 7.23 (t, J = 7.5 Hz, 1H), 7.19 (dd, J = 8.5 Hz, 2.0 Hz, 1H), 6.51
(d, J = 8.0 Hz, 1H), 6.34 (d, J = 8.5 Hz, 1H), 5.20 (s, 1H, carborane−
CH) 2.82−1.70 (br, 1H, BH). 13C NMR (125 MHz, (CD3)2CO):
180.62, 156.53, 152.59, 150.96, 148.90, 141.38, 140.64, 133.90,
131.95, 130.97, 129.12, 128.47, 126.70, 125.05, 124.93, 124.35,
117.75, 76.94 (B−C), 61.13 (B−C). IR (KBr): υ 2581 cm−1 (B−H).
Elemental analysis calcd (%) for C40H44B20N4S2IrPF6: C 40.09, H
3.70, N 4.68. Found: C 40.02, H 3.75, N 4.60.
X-ray Crystallography. Diffraction data of C1 were collected on
a Bruker Smart APEX CCD diffractometer with graphite mono-
chromated Mo Ka radiation (λ 0.71073 Å). All data were collected at
room temperature, and the structures were solved by direct methods
and subsequently refined on F2 by using full-matrix least-squares
techniques (SHELXL).50 SADABS51 absorption corrections were
applied to the data. All non-hydrogen atoms were anisotropically
refined, and hydrogen atoms were located at the calculated positions.
All calculations were performed using the Bruker program Smart.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (No. 21601125), the Chenguang Scholar
of Shanghai Municipal Education Commission (No. 16CG64),
the Shanghai Gaofeng & Gaoyuan Project for University
Academic Program Development, the research funding of
Shanghai Institute of Technology (ZQ2020-10 and
XTCX2020-24).
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c03625.
■
sı
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Accession Codes
CCDC 2047084 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
Corresponding Authors
Zi-Jian Yao − School of Chemical and Environmental
Engineering, Shanghai Institute of Technology, Shanghai
201418, China; Key Lab of Synthetic Chemistry of Natural
■
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