Reaction of Cyclometalated Phosphine Chloride Iridium(III) Complexes with Imidazole

Article abstract of DOI:10.1134/S1070363220060110

Abstract: A series of iridium complexes with various cyclometalated ligands and phosphines [Ir(N^C)₂(PR₃)Cl], where N^C = 2-(benzothiophen-3-yl)pyridine and 2-phenylpyridine and R = phenyl and p-methoxyphenyl, were obtained. It was shown that the complexes of this type react with imidazole under mild conditions. The phosphine and chloride ligands are consecutively substituted to give imidazole-containing derivatives. The photophysical properties of all the synthesized compounds were investigated in detail. The imidazole-containing complexes demonstrate efficient triplet luminescence in solution with quantum yields up to 60percent, which is sensitive to molecular oxygen.

Full text of DOI:10.1134/S1070363220060110

ISSN 1070-3632, Russian Journal of General Chemistry, 2020, Vol. 90, No. 6, pp. 1005–1011. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Obshchei Khimii, 2020, Vol. 90, No. 6, pp. 911–918.
Reaction of Cyclometalated Phosphine Chloride Iridium(III)
Complexes with Imidazole
S. A. Chapaikinaa, A. I. Solomatinaa,*, and S. P. Tunika
a St. Petersburg State University, St. Petersburg, 199034 Russia
*e-mail: nastisol@gmail.com
Received January 29, 2020; revised January 29, 2020; accepted February 29, 2020
Abstract—Aseries of iridium complexes with various cyclometalated ligands and phosphines [Ir(N^C)2(PR3)Cl],
where N^C = 2-(benzothiophen-3-yl)pyridine and 2-phenylpyridine and R = phenyl and p-methoxyphenyl, were
obtained. It was shown that the complexes of this type react with imidazole under mild conditions. The phosphine and
chloride ligands are consecutively substituted to give imidazole-containing derivatives. The photophysical proper-
ties of all the synthesized compounds were investigated in detail. The imidazole-containing complexes demonstrate
efficient triplet luminescence in solution with quantum yields up to 60%, which is sensitive to molecular oxygen.
Keywords: cyclometalated iridium(III) complexes, phosphine ligands, phosphorescence, imidazole
DOI: 10.1134/S1070363220060110
The problem of covalent conjugation of biomolecules
with luminescent markers is extremely urgent for
the research on the behavior of active components of
biosystems (antibodies, peptides) [1], as well as for the
design of dyes for targeted bioimaging [2, 3]. Covalent
conjugation is commonly accomplished by the reaction
of the succinimide ester [4] and isothiocyanate groups
of organic dyes with the amino groups of biomolecules
[1, 5], as well as approaches involving reactions of the
thiol groups of biomolecules with the maleimide function
of dyes or click chemistry reactions [6].
It should be noted that the final result of these reactions
depends on the electronic properties of the phosphine
(PR3); almost all phosphine complexes give the products
of substitution of the chloride ligand by imidazole,
whereas the reaction of the complex containing the most
acceptor perfluorinated triphenylphosphine results in
substitution of both the phosphine and chloride ligands
[12]. We showed that histidine-containing molecules
enter such conjugation reactions too, and the resulting
conjugates can be used as luminescent sensors for
molecular oxygen in biological systems [12]. Therefore,
research into the coordination conjugation of small
molecules and biological compounds with organometallic
luminophores are of considerable interest for coordination
chemistry, as well as for functional bioimaging in terms
of potential application of such conjugates.
However, luminescent transition metal complexes
can conjugate with biomolecules not only by covalent
binding with ligand periphery, but also by coordination
to the metal center, i.e. in this case the protein molecule
acts as a ligand [5, 7].
Cyclometalated iridium solvation complexes
[Ir(N^C)2Solv2]+, where N^C is a cyclometalating ligand
and Solv is solvent, can react with the imidazole ring
of histidine by substituting the solvent molecules in the
complex by the imidazole nitrogen to form luminescent
conjugates [8–10]. In our recent works [11, 12] we
showed that the reactions of nonluminescent or weakly
luminescent cyclometalated phosphine chloride platinum
complexes [Pt(N^C)(PR3)Cl] with imidazole-containing
molecules involve substitution of the chloride ligand by
imidazole, yielding brightly photoluminescent products.
In the present work we synthesized a series of
phosphine chloride iridium complexes [Ir(N^C)2PR3Cl]
similar to as the above-described platinum complexes
and studied their reaction with imidazole. The series
of cyclometalated iridium complexes was prepared
according to Scheme 1.
The complexes were synthesized by a modified
procedure [13] by the reaction of a cyclometalated
dimeric precursor with the corresponding phosphine in
dichloromethane in an inert atmosphere. The reaction
1005

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CHAPAIKINA et al.
Scheme 1.
products were isolated by column chromatography and
recrystallized from dichloromethane–hexane mixture.
The structures of the complexes were determined by
31Pand 1H (1D and 2D 1H–1H COSY) NMR spectroscopy
and ESI+ mass spectrometry. The mass spectra of
complexes 1–3 show signals of molecular fragments
formed by the loss of chloride ion, as well as [M + Na]+ and
[M + K]+ cations. The isotope distributions of the signals
are completely consistent with the stoichiometry of the
corresponding species. The positions of the NMR signals,
as well as their multiplicities and integral intensities are
in full agreement with the molecular structure shown in
Fig. 1 and correlate well with published data for similar
compounds [13, 14]. Thus, the obtained spectral evidence
suggests that complexes 1–3 do not dissociate in solution
and have the same molecular structure as in the solid state.
The structures of complexes 2 and 3 in the solid
state were established by XRD analysis (Fig. 1). The
compounds have an octahedral geometry typical of
Ir(III) and have the two cyclometalated ligands and two
monodentate ligands cis to each other. In view of the
strong trans effect of the donor carbon atoms of the N^C
ligands, the nitrogen atoms are located in trans position
to each other, and the phosphine and chloride ligands
are arranged trans to the coordinated carbon atoms of
the cyclometalated chelate. The bond lengths and angles
in the complexes are typical of compounds of this type
[13–15].
ꢀɚꢁꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢀEꢁ
Fig. 1. Molecular structures of complexes (а) 2 and (b) 3 in the solid phase. Selected bond lengths (Å) and angles (deg): 2, Ir–N1
2.057(2), Ir–C1 2.012(3), Ir–N2 2.064(2), Ir–C2 2.040(2), Ir–Cl 2.4724(6), Ir–P 2.4069(6), C1IrN1 80.6(1), C2IrN2 80.10(9), C2IrC1
88.8(1), ClIrP 88.84(2); 3, Ir–N1 2.059(3), Ir–C1 2.007(4), Ir–N2 2.079(3), Ir–C2 2.057(4), Ir–Cl 2.4705(9), Ir–P 2.428(1), C1IrN1
80.1(1), C2IrN2 80.3(1), C2IrC1 88.2(1), ClIrP 92.29(3).
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REACTION OF CYCLOMETALATED PHOSPHINE CHLORIDE IRIDIUM(III) COMPLEXES
1007
Table 1. Photophysical properties of iridium complexes 1–3 in dichloromethane
Comp.
no.
λmax, nm
λex, nm
λem, nm
Фaer, %
Фdeaer, %
τaer, μs
τdeaer, μs
(ε×10–3, М–1·cm–1)
1
2
3
257 (30), 388 sh (3)
245 (62), 390 (4)
290 (23), 328 sh (16), 437 (5) 290, 330, 440 590, 640
260, 390 sh
250, 390 sh
485, 513
487, 515
0.6±0.1
0.4±0.1
0.9±0.1
0.9±0.1 0.040±0.006 0.056±0.008
1.0±0.2 0.038±0.006 0.15±0.02
13±2
0.65±0.09
9±1
Complexes 1–3 weakly luminesce in solution. The
and their reactions with imidazole lead to consecutive
substitution of the phosphine and chloride ligands.
According to the 31P NMR data, phosphine, having left
the coordination sphere, readily oxidizes to phosphine
oxide. The fact that the synthesized iridium complexes
behave differently from their platinum analogs can be
explained by the higher rigidity of the d6 configuration
of Ir(III) compared to the d8 configuration of Pt(II), as
well as the strong trans effect of the coordinated carbon
atom on the phosphine ligand in iridium complexes. The
main products of the reaction with imidazole in solution
at room temperature are a monosubstituted imidazole
chloride complex, as well as a disubstituted cationic
product (Scheme 2).
photophysical characteristics of these compounds are
listed in Table 1 (see Supplementary materials). All
the complexes show Stokes shifts of about 150 nm,
excited state lifetimes falling in the microsecond range,
and luminescence quenching by molecular oxygen,
which suggests a triplet origin of the excited state and
provides evidence showing that these compounds exhibit
phosphorescence. The emission bands of the complexes
demonstrate fine structure with energy spacing between
the components of about 1100–1350 cm–1 corresponding
to the vibration frequencies of the aromatic systems
of the ortho-metalated ligands. These data point to
preferential localization of the emission excited state
on the cyclometalated ligand, which is typical of
similar ortho-metalated iridium complexes [14, 16–18].
Complexes 1 and 2 with 2-phenylpyridine show similar
photophysical characteristics, whereas complex 3 on the
basis of pyridylbenzothiophene, which has an extended
aromatic system, demonstrates red- shifted excitation
and luminescence bands. These findings provide further
evidence for the ligand-centered nature of the excited state
localized on the cyclometalated fragment. The quantum
yields of the complexes vary from fractions of a percent
to 13%; complex 3 demonstrates the highest luminescence
efficiency both in an aerated and a deaerated solution.
The products of the reaction of complex 1 with
imidazole, specifically monosubstituted [Ir(ppy)2ImCl]
(4) and disubstituted complex [Ir(ppy)2(Im)2]Cl (5),
were isolated pure by recrystallization from a mixture of
dichloromethane and diethyl ether and characterized in
solution by 1Н NMR spectroscopy and mass spectrometry.
The solid-phase structure of complex 4 was established
by XRD analysis (Fig. 2).
Imidazole derivatives 4 and 5 exhibit intense
luminescence in solution at room temperature. The
photophysical characteristics of these compounds in
aerated and deaerated dilute solutions (с = 1–5×10–5 M)
are listed in Table 2. The absorption spectra of both
compounds have similar patterns characteristic of
cyclomelated Ir(III) complexes [19]: the bands near
250 nm relate to π–π* transitions in the aromatic fragments,
and the weaker bands in the range 350–500 nm are
The reaction of complexes 1–3 with imidazole
(Im) was studied in situ by NMR spectroscopy of the
reaction mixtures. It was found that the synthesized
iridium complexes, unlike their platinum analogs, are
more susceptible to substitution of triphenylphohsphine,
Scheme 2.
×
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CHAPAIKINA et al.
ꢀɚꢁꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢂꢀEꢁ
Fig. 2. (а) Molecular structure of complex 4 in the solid phase and (b) packing of molecules of complex 4 in the crystal cell (view
along the c axis). Selected bond lengths (Å) and angles (deg): Ir–N1 2.043(4), Ir–C1 2.033(2), Ir–N2 2.127(4), Ir–Cl 2.492(2), C1IrN1
80.2(1), N2IrN1 97.1(3), ClIrN1 97.3(1).
associated with MLCT excited states. The luminescence
spectra of the complexes show fine vibrational structure
corresponding to the vibration frequencies of the
cyclometalated fragments. The emission maximum
of monoimidazole complex 4 is red-shifted by about
20 nm compared to the respective maxima of phosphine
complexes 1 and 2, and bisimidazole complex 5. The
emission quantum yields of the complexes are about 60%
in degassed solutions, and their excited state lifetimes fall
in the microsecond range. The luminescence quantum
yield and excited state lifetime are sensitive to molecular
oxygen and increase 20 times in a degassed solution,
which suggests a triplet excited state.
with imidazole much differ from those characteristic
of analogous phosphine chloride platinum complexes,
it is obvious that the synthesized iridium complexes
can react with imidazole-containing biomolecules to
form luminescent covalent conjugates. This opens the
way for the use of such complexes as selective labeling
agents for imidazole-containing compounds and as
luminescent sensors for histidine and histidine-containing
biomolecules.
EXPERIMENTAL
2-Phenylpyridine (ppy), 2-(benzo[b]thiophen-2-yl)-
pyridine (btpy), imidazole, triphenylphosphine, tris(4-
methoxyphenyl)phosphine, and IrCl3·6H2O were
purchased from Sigma–Aldrich and Alfa Aesar and
used as received. Dichloromethane was purified by a
conventional procedureи [20]. Iridium cyclometalated
precursors [Ir(N^C)2μ-Cl]2 were prepared by a standard
procedure (100°C, water–2-ehoxyethanol) [21].
Thus, the reaction of phosphine chloride iridium
complexes with imidazole involves elimination of the
phosphine ligand and formation of the monoimidazole
complex [Ir(N^C)2ImCl] and bisimidazole complex
[Ir(N^C)2(Im)2]Cl. Even though the pathway and result of
the reactions of the phosphine chloride iridium complexes
Table 2. Photophysical properties of iridium complexes 4 and 5 in aerated and deaerated solutions
Comp.
no.
λmax, nm
λex, nm
λem, nm
Фaer, % Фdeaer, %
τaer, μs
τdeaer, μs
(ε×10–3, М–1 cm–1)
4a
268 (32), 305 sh (13), 336 (6), 268, 305 sh, 336, 360 506,
360 sh (5), 400 (3.5), 435 sh sh, 400, 435 sh, 450, 530 sh
(2.2), 452 (2.0), 485 sh (0.6) 483
260 (41), 270 sh (36), 292 sh 270, 290 sh, 325 sh, 485, 517,
(19), 325 sh (8,4), 344 (6.4), 345 sh, 388, 420 sh, 555 sh
2.5±0.4
58±8
0.063±0.009
1.3±0.2
5b
1.1±0.2
57±8
0.046±0.007
2.2±0.3
388 (4.4), 425 sh (2.5), 475
(0.3)
a In dichloromethane.
b In methanol.
473
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REACTION OF CYCLOMETALATED PHOSPHINE CHLORIDE IRIDIUM(III) COMPLEXES
1009
The H, H–1H COSY, and 31P NMR spectra were
821.1408 [M + Na]+ (calculated for C40H31ClIrN2NaP:
821.1433).
[Ir(ppy)2(P(Php-OMe)3)Cl] (2) was prepared in
1
1
registered on Bruker Avance III instruments (400 МHz).
The ESI+ mass spectra were measured on MaXis and
Bruker micrOTOF 10223 instruments for methanol and
dichloromethane solutions.
a similar way from tris(4-methoxyphenyl)phosphine.
1
Yield 82%, yellow-green crystals. H NMR spectrum
(acetone-d6), δ, ppm: 9.29 d (1H, 3JHH = 5.9 Hz), 9.00 d
(1H, 3JHH = 5.7 Hz), 8.13 d (1H, 3JHH = 8.2 Hz), 7.92 t. d
Photophysical measurements were performed in
dichloromethane solutions. When necessary, before
measuring the excited state lifetime and the luminescence
quantum yield, the solutions were carefully degassed by
purging with argon.
3
4
3
(1H, JHH = 7.8, JHH = 1.3 Hz), 7.84 d (1H, JHH
=
7.9 Hz), 7.73–7.69 m (2H), 7.58 d (1H, 3JHH = 7.5 Hz),
7.24 m (6H), 6.99 t. d (1H, 3JHH = 6.7, 4JHH = 1.3 Hz),
6.93 t. d (1H, JHH = 6.6, JHH = 1.3 Hz), 6.82–6.77 m
3
4
The UV absorption spectra were run on a Shimadzu
UV-1800 spectrophotometer for 1−5×10–5 М solutions
(l = 1 cm). The emission spectra were obtained on a
Horiba Fluomax-4 spectrofluorimeter for 3×10–5
solutions. The absolute luminescence quantum yields
were determined by the comparison method [22] using
as reference a solution of [Ru(bpy)3] in water (Φlum
0.040) [23]. The refractive indices of dichloromethane
and methanol in calculations were taken to be equal
to 1.424 and 1.328, respectively [24]. The lifetime
in solution was determined by time-correlated single
photon counting (TCSPC) using a system comprising
a DTL-399QT pulsed laser (Laser Export, Russia), a
MUM monochromator (LOMO, Russia), an H10682
photon counting head (Hamamatsu, Japan), and a P7887
multiple-event time digitizer (FAST ComTec Germany).
The luminescence decay curves were fitted using Origin
9.0 software.
3
4
(2H), 6.71 d. d (6H, JHH = 8.8, JHH = 1.4 Hz), 6.65 t
(1H, 3JHH = 7.4 Hz), 6.54 t (1H, 3JHH = 7.4 Hz), 5.99 d
3
3
3
(1H, JHH = 7.7 Hz), 5.83 d. d (1H, JHH = 7.1, JHH
=
М
4.9 Hz), 3.78 с (9H). 31P NMR spectrum (acetone-d6):
δР –7.38. Mass spectrum (ESI), m/z: 853.2169 [M – Cl]+
(calculated for C43H37IrN2O3P: 853.2174).
=
[Ir(btpy)2(PPh3)Cl] (3) was prepared in a similar
way from the dimer [Ir(btpy)2μ-Cl]2. Yield 89%, red
1
crystals. H NMR spectrum (CDCl3), δ, ppm: 9.44 d
(1H, 3JHH = 5.6 Hz), 9.01 d (1H, 3JHH = 5.8 Hz), 7.78 t. d
3
4
3
(1H, JHH = 7.4, JHH = 1.4 Hz), 7.67 d (1H, JHH
=
3
7.1 Hz), 7.62 m (2H), 7.53 t (1H, JHH = 8.2 Hz),
7.40–7.35 m (6H), 7.25–7.20 m (4H), 7.10–6.98 m (8H),
3
4
6.75 t. d (1H, JHH = 7.6, JHH = 0.9 Hz), 6.67–6.60 m
3
3
(3H), 6.05 d (1H, JHH = 8.2 Hz), 5.50 d (1H, JHH
=
8.3 Hz). 31PNMR spectrum (CDCl3): δР –6.68 ppm. Mass
spectrum (ESI), m/z: 875.1262 [M – Cl]+ (calculated
for C44H31IrN2PS2: 875.1295), 933.0854 [M + Na]+
(calculated for C44H31ClIrN2NaPS2: 933.0872).
[Ir(ppy)2(PPh3)Cl] (1). Amixture of [Ir(ppy)2μ-Cl]2
(30 mg, 0.028 mmol) and triphenylphohsphine (15 mg,
0.056 mmol) in 10 mL of degassed dichloromethane
was stirred for 1 h under argon, and then the solvent was
evaporatedtodryness.Thetargetcompoundwaspurifiedby
flash chromatography on silica gel, eluent dichloroethane.
Crystals suitable for XRD analysis were obtained from
dichloroethane–hexane mixture. Yield 38 mg (85%),
[Ir(ppy)2(Im)Cl] (4). Imidazole (2 mg, 0.029 mmol)
was added to a solution of complex 1 (20 mg,
0.025 mmol) in 3 mL of dichloromethane. The target
compound was isolated from the reaction mixture by
recrystallization from dichloromethane–diethyl ether
mixture at room temperature. Yield 10 mg (66%), light
yellow crystals. 1H NMR spectrum (acetone-d6), δ, ppm:
9.97 d. d (1H, 3JHH = 5.8, 4JHH = 0.7 Hz), 8.25 с(1H), 8.15 d
(1H, 3JHH = 5.6 Hz), 8.06 d (1H, 3JHH = 7.4 Hz), 8.00 d (1H,
1
yellow-green crystals. H NMR spectrum (CDCl3), δ,
ppm: 9.34 d (1H, JHH = 5.9 Hz), 8.89 d (1H, JHH
5.8 Hz), 7.93 d (1H, 3JHH = 7.9 Hz), 7.73 t. d (1H, 3JHH
3
3
=
=
3JHH = 8.2 Hz), 7.88–7.82 m (2H), 7.68 d. d (1H, 3JHH
=
=
4
4
3
4
7.8, JHH = 1.3 Hz), 7.61–7.57 m (2H), 7.51–7.47 m
7.5, JHH = 0.7 Hz), 7.64 d. d (1H, JHH = 7.6, JHH
(2H), 7.31–7.23 m (9H), 7.13 m (6H), 6.88 t (1H, 3JHH
7.0 Hz,), 6.85 t (1H, 3JHH = 7.4 Hz), 6.80–6.76 m (2H),
6.74 t. d (1H, 3JHH = 6.7, 4JHH = 1.4 Hz), 6.57 d (1H, 3JHH
=
1.2 Hz), 7.30 t (1H, 3JHH = 6.6, 4JHH = 1.4 Hz), 7.17 t (1H,
3JHH =6.6Hz), 7.12s(1H), 6.96s(1H), 6.83t. d(1H, 3JHH
=
=
4
3
3
=
7.5, JHH = 1.0 Hz), 6.72 t. d (2H, JHH = 7.6, JHH
7.4,4JHH =1.1Hz),5.94d(1H,3JHH =7.8Hz),5.88d.d(1H,
3JHH = 6.8, 3JHH = 4.8 Hz). 31P NMR spectrum (CDCl3):
δР –2.15 ppm. Mass spectrum (ESI), m/z: 763.1829
[M – Cl]+ (calculated for C40H31IrN2P: 763.1857),
1.2 Hz), 6.61 t. d (1H, 3JHH = 7.4, 4JHH = 1.3 Hz), 6.36 d. d
(1H, JHH = 7.7, JHH = 0.8 Hz), 6.22 d (1H, JHH
7.4 Hz). Mass spectrum (ESI), m/z: 569.1311 [M – Cl]+
3
4
3
=
(calculated for C25H20IrN4: 569.1318).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 6 2020

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CHAPAIKINA et al.
[Ir(ppy)2(Im)2]Cl (5) were prepared similarlу from
SUPPLEMENTARY MATERIALS
complex 1 (20 mg, 0.025 mmol) and imidazole (17 mg,
Supplementary materials are available for this article at
https://doi.org/10.1134/S1070363220060110 and are accessible
for authorized users.
0.250 mmol). Yield 12 mg (71%), light yellow crystalline
1
material. H NMR spectrum (methanol-d4), δ, ppm:
8.65 d. d (1H, 3JHH = 5.8, 4JHH = 0.7 Hz), 8.00 d (1H, 3JHH
=
8.0 Hz), 7.88 t. d (1H, 3JHH = 7.9, 4JHH = 1.5 Hz), 7.63 d. d
(1H, 3JHH = 7.7, 4JHH = 1.0 Hz), 7.59 s (1H), 7.29 d. d. d
REFERENCES
1. Connell, T.U. and Donnelly, P.S., Coord. Chem. Rev.,
2018, vol. 375, p. 267.
https://doi.org/10.1016/j.ccr.2017.12.001
2. Gonçalves, M.S.T., Chem. Rev., 2009, vol. 109,
no. 1, p. 190.
https://doi.org/10.1021/cr0783840
3. Zhao, Q., Huang, C., and Li, F., Chem. Soc. Rev., 2011,
vol. 40, no. 5, p. 2508.
(1H, 3JHH = 7.3, 5.8, 4JHH = 1.4 Hz), 7.10 t (1H, 3JHH
1.4 Hz), 6.96 t (1H, 3JHH = 1.3 Hz), 6.88 t. d (1H, 3JHH
=
=
=
4
3
4
7.5, JHH = 1.2 Hz), 6.80 t. d (1H, JHH = 7.4, JHH
1.3 Hz), 6.37 d. d (1H, 3JHH = 7.5, 4JHH = 0.9 Hz). Mass
spectrum (ESI), m/z: 637.1679 [M – Cl]+ (calculated for
C28H24IrN6: 637.1693).
X-ray diffraction analysis. The solid-phase molecular
structures of the synthesized complexes were determined
by XRD analysis on Oxford Diffraction diffractometers
at 100–293 К using CuKα radiation. Data treatment was
performed using CrysAlisPro [25]. The structures were
solved by direct methods or the double-space algorithm
and refined using SHELX programs [26, 27] integrated
into the OLEX2 software package [28]. The unit cell of
a crystal of compound 4 contains a disordered solvent
which was included (using SQUEEZE/PLATON) as a
diffuse scattering without specific atomic positions [29].
The crystallographic data are deposited at the Cambridge
Crystallographic Data Center.
https://doi.org/10.1039/c0cs00114g
4. Hermanson, G.T., Bioconjugate Techniques, London:
Elsevier, 2013, p. 229.
https://doi.org/10.1016/B978-0-12-382239-0.00003-0
5. Hoyt, E.A., Cal, P.M.S.D., Oliveira, B.L.,
and Bernardes, G.J.L., Nat. Rev. Chem., 2019, vol. 3,
no. 3, p. 147.
https://doi.org/10.1038/s41570-019-0079-1
6. Nwe, K. and Brechbiel, M.W., Cancer Biother.
Radiopharm., 2009, vol. 24, no. 3, p. 289.
https://doi.org/10.1089/cbr.2008.0626
7. Lo, K.K.-W., Choi, A.W.-T., and Law, W.H.-T., Dalton
Trans., 2012, vol. 41, no. 20, p. 6021.
https://doi.org/10.1039/c2dt11892k
8. Ma, D.-L., Wong, W.-L., Chung, W.-H., Chan, F.-Y.,
So, P.-K., Lai, T.-S., Zhou, Z.-Y., Leung, Y.-C.,
and Wong, K.-Y., Angew. Chem. Int. Ed., 2008,
vol. 47, no. 20, p. 3735.
Complex 2. Unit cell parameters: space group P121/
n1, a = 14.1462(1) Å, b = 13.4143(1) Å, c = 20.2500(1) Å,
β = 107.211(1)°, V = 3670.61(4) Å3, Z = 4; R1 = 3.8,
CCDC 1979619.
https://doi.org/10.1002/anie.200705319
9. Ma, X., Jia, J., Cao, R., Wang, X., and Fei, H., J. Am.
Chem. Soc., 2014, vol. 136, no. 51, p. 17734.
https://doi.org/10.1021/ja511656q.
10. Wang, X., Jia, J., Huang, Z., Zhou, M., and Fei, H.,
Chem. Eur. J., 2011, vol. 17, no. 29, p. 8028.
https://doi.org/10.1002/chem.201100568
11. Solomatina, A.I., Chelushkin, P.S., Krupenya, D.V., Podko-
rytov, I.S., Artamonova, T.O., Sizov, V.V., Melnikov, A.S.,
Gurzhiy, V. V., Koshel, E.I., Shcheslavskiy, V.I., and
Tunik, S.P., Bioconjug. Chem., 2017, vol. 28, no. 2,
p. 426.
https://doi.org/10.1021/acs.bioconjchem.6b00598
12. Solomatina, A.I., Chelushkin, P.S., Abakumova, T.O.,
Zhemkov, V.A., Kim, M., Bezprozvanny, I., Gurzhiy, V.V.,
Melnikov, A.S., Anufrikov, Y.A., Koshevoy, I.O.,
Su, S.-H., Chou, P.-T., and Tunik, S.P., Inorg. Chem.,
2019, vol. 58, no. 1, p. 204.
Complex 3. Unit cell parameters: space group P212121,
a = 13.1906(7) Å, b = 13.6622(7) Å, c = 19.8994(9) Å, V =
3586.1(3) Å3, Z = 4, R1 = 2.2, CCDC 1979862).
Complex 4. Unit cell parameters: space group R-3c,
a = b = 23.5220(2) Å, c = 25.2745(2) Å, γ = 120°, V =
12110.5(2) Å3, Z = 18, R1 = 3.3, CCDC 1979863.
FUNDING
The research was performed with financial support of
the Russian Foundation for Basic Research (project no.
18-33-00954) using the equipment of the core facilities of
St. Petersburg State University Research Park: Magnetic
Resonance Research Centre, Centre for X-ray Diffraction
Studies, Centre for Optical and Laser Materials Research, and
Chemical Analysis and Materials Research Centre.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
https://doi.org/10.1021/acs.inorgchem.8b02204
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REACTION OF CYCLOMETALATED PHOSPHINE CHLORIDE IRIDIUM(III) COMPLEXES
1011
13. Wang, Y., Teng, F., Tang, A., Wang, Y., and Xu, X.,
Acta Crystallogr. Sect. E, 2005, vol. 61, no. 4, p. 778.
https://doi.org/10.1107/S1600536805008913
21. Nonoyama, M., Bull. Chem. Soc. Jpn., 1974, vol. 47,
no. 3, p. 767.
https://doi.org/10.1246/bcsj.47.767
22. Brouwer, A.M., Pure Appl. Chem., 2011, vol. 83,
no. 12, p. 2213.
14. Wang, Y.M., Teng, F., Gan, L.H., Liu, H.M.,
Zhang, X.H., Fu, W., Wang, Y.S., and Xu, X.R.,
J. Phys. Chem. C, 2008, vol. 112, no. 12, p. 4743.
https://doi.org/10.1021/jp076669a
https://doi.org/10.1351/PAC-REP-10-09-31
23. Suzuki, K., Kobayashi, A., Kaneko, S., Takehira, K., Yo-
shihara, T., Ishida, H., Shiina, Y., Oishi, S., and Tobita, S.,
Phys. Chem. Chem. Phys., 2009, vol. 11, no. 42, p. 9850.
https://doi.org/10.1039/b912178a
15. Chen, Z.Q., Shen, X., Xu, J.X., Zou, H., Wang, X.,
Xu, Y., and Zhu, D.R., Inorg. Chem. Commun.,
2015, vol. 61, p. 152.
24. LeBel, R.G. and Goring, D.A.I., J. Chem. Eng. Data,
1962, vol. 7, no. 1, p. 100.
https://doi.org/10.1016/j.inoche.2015.09.013
16. Zhang, X., Zhang, L.Y., Shi, L.X., Chen Z.N., Inorg.
Chem. Commun., 2009, vol. 12, no. 8, p. 758.
https://doi.org/10.1021/je60012a032
25. CrysAlisPro, Rigaku Oxford Diffraction, Version:
1.171.39.35a, 2017.
https://doi.org/10.1016/j.inoche.2009.06.008
26. Sheldrick, G.M., Acta Crystallogr., Sect. A, 2015,
vol. 71, no. 1, p. 3.
17. Flamigni, L., Barbieri, A., Sabatini, C., Ventura, B., and
Barigelletti, F., Top. Curr. Chem., 2007, vol. 281, p. 143.
https://doi.org/10.1007/128_2007_131
https://doi.org/10.1107/S2053273314026370
27. Sheldrick, G.M., Acta Crystallogr., Sect. C, 2015,
vol. 71, no. 1, p. 3.
18. Huckaba, A.J. and Nazeeruddin, M.K., Comm. Inorg.
Chem., 2017, vol. 37, no. 3, p. 117.
https://doi.org/10.1107/S2053229614024218.
28. Dolomanov, O.V., Bourhis, L.J., Gildea, R.J., How-
ard, J.A.K., and Puschmann, H., J. Appl. Crystallogr.,
2009, vol. 42, no. 2, p. 339.
https://doi.org/10.1080/02603594.2016.1207064
19. Wu, N., Cao, J.J., Wu, X.W., Tan, C.P., Ji, L.N., and
Mao, Z.W., Dalton Trans., 2017, vol. 46, no. 39, p. 13482.
https://doi.org/10.1039/c7dt02477k
https://doi.org/10.1107/S0021889808042726
29. Spek, A.L., Acta Crystallogr., Sect. C, 2015, vol. 71,
no. 1, p. 9.
20. Armarego, W.L.F. and Chai, C.L.L., Purification of
Laboratory Chemicals, Oxford: Elsevier, 2009, p. 88.
https://doi.org/10.1016/B978-1-85617-567-8.50012-3
https://doi.org/10.1107/S2053229614024929
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 6 2020