C∧C Cyclometalated Platinum(II) Complexes with Dibenzofuranyl-1,2,4-triazol-5-ylidene Ligands: Synthesis, Characterization, and Photoluminescent Properties

Article abstract of DOI:10.1021/acs.organomet.5b00136

Two series of new platinum(II) NHC complexes with C^∧C cyclometalating 1-(dibenzo[b,d]furan-4-yl)-4-methyl-1H-1,2,4-triazole and 1-(dibenzo[b,d]furan-2-yl)-4-methyl-1H-1,2,4-triazole ligands and several β-diketonato auxiliary ligands (acetylacetonato, dibenzoylmethanato, and dimesitoylmethanato) were synthesized, characterized (NMR spectroscopy, elemental analysis, and X-ray crystallography for two complexes) and investigated in terms of their photoluminescence properties. All complexes are strongly emissive at room temperature in a 2 wt % complex doped poly(methyl methacrylate) film at room temperature. Using dibenzoylmethanato as auxiliary ligand leads to a broad emssion band with a maximum in the green region of the spectrum, whereas the complexes with acetylacetonato and dimesitoylmethanato ligands reveal structured blue emissions with wavelengths that strongly depend on the arrangement of the dibenzo[b,d]furan (DBF) unit.

Full text of DOI:10.1021/acs.organomet.5b00136

Article
pubs.acs.org/Organometallics
C∧C* Cyclometalated Platinum(II) Complexes with Dibenzofuranyl-
1,2,4-triazol-5-ylidene Ligands: Synthesis, Characterization, and
Photoluminescent Properties
Mario Tenne,† Stefan Metz,‡ Gerhard Wagenblast,‡ Ingo Munster,‡ and Thomas Strassner*,†
̈
†Physikalische Organische Chemie, Technische Universitat Dresden, 01069 Dresden, Germany
̈
‡BASF SE, 67056 Ludwigshafen, Germany
S
* Supporting Information
ABSTRACT: Two series of new platinum(II) NHC complexes
with C∧C* cyclometalating 1-(dibenzo[b,d]furan-4-yl)-4-methyl-
1H-1,2,4-triazole and 1-(dibenzo[b,d]furan-2-yl)-4-methyl-1H-
1,2,4-triazole ligands and several β-diketonato auxiliary ligands
(acetylacetonato, dibenzoylmethanato, and dimesitoylmethana-
to) were synthesized, characterized (NMR spectroscopy,
elemental analysis, and X-ray crystallography for two complexes)
and investigated in terms of their photoluminescence properties.
All complexes are strongly emissive at room temperature in a 2
wt % complex doped poly(methyl methacrylate) film at room
temperature. Using dibenzoylmethanato as auxiliary ligand leads
to a broad emssion band with a maximum in the green region of
the spectrum, whereas the complexes with acetylacetonato and
dimesitoylmethanato ligands reveal structured blue emissions with wavelengths that strongly depend on the arrangement of the
dibenzo[b,d]furan (DBF) unit.
on 1-phenylimidazole.30,31 These emitters reveal intense
phosphorescence at room temperature in the blue to green
INTRODUCTION
■
Phosphorescent transition-metal complexes are known for their
region of the spectrum, with emission properties that strongly
depend on the substitution pattern of the C∧C* cyclo-
metalating ligand. Due to the promising results, a varity of
platinum(II) complexes with modified C∧C* cyclometalating
ligands and chelating ancillary ligands were developed to
investigate their influence on the photophysical properties.32−40
Among those are very efficient blue emitters showing QYs
above 90%, which are very attractive for applications in
OLEDs.30,35,39 Two of them contain a cyclometalating ligand
derived from dibenzo[b,d]furanylimidazole, a motif that also
emerged as a convenient ligand to obtain strong blue emissions
from platinum and iridium complexes.30,39,41 To obtain emitter
molecules with improved photoluminescence properties,
especially a reduced lifetime of the excited state, we developed
two new triazol-5-ylidene ligands containing a 2-dibenzo[b,d]-
furanyl unit and a 4-dibenzo[b,d]furanyl unit and investigated
their influence on the photophysical properties of platinum(II)
complexes with a set of different β-diketonate auxiliary ligands
(acetylacetonato, dibenzoylmethanato, and dimesitoylmethana-
to).
extraordinary photoluminescence properties. In contrast to
most of the conventional purely organic emitter molecules,
transition-metal complexes are not limited to a quantum yield
(QY) of 25%. The heavy-metal-induced strong spin−orbit
coupling (SOC) results in an admixture of the metal-centered d
orbitals to the orbitals of the ligands, which increases the rate of
intersystem crossing (ISC) from the excited singlet state to the
triplet state and therefore allows quantum efficiencies of up to
100%.1 Especially complexes with iridium and platinum have
been found to be promising emitters for potential application in
the fields of bioimaging2−5 and organic light emitting devices
(OLEDs) for displays and lighting panels.6−13 Among those,
cyclometalated complexes of the general structure [M-
(C∧N)1−2(O∧O)] have been proven to be efficient emit-
ters,14−24 showing photophysical properties that strongly
depend on the C∧N cyclometalating ligands. In the last few
years a multitude of efficient emitter molecules have been
developed containing C∧N ligands especially based on 2-
phenylpyridine,9,16,25 but also on phenylazoles such as 2-
phenylbenzimidazole.26,27 Lately, platinum(II) complexes with
C∧C* cyclometalating NHC ligands of the general structure
[Pt(C∧C*)(O∧O)] have also attracted a lot of scientific interest
due to their extraordinary emission properties. After these
complexes were reported in patents in 2006,28,29 we and others
synthesized and investigated the first emitters of this class based
Received: February 17, 2015
© XXXX American Chemical Society
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Scheme 1. Preparation of the Ligand Precursors 3 and 6
11, and 12 were obtained in yields of 17−23%, whereas 10 was
obtained in a yield of only 7%.
RESULTS AND DISCUSSION
■
Synthesis and Characterization. The ligand precursors 3
and 6 were synthesized in three steps (Scheme 1). The
synthesis of 1-(dibenzo[b,d]furan-4-yl)-4-methyl-1,2,4-triazo-
lium iodide (3) started with a selective lithiation reaction of
dibenzo[b,d]furan followed by bromination, leading to 4-
bromodibenzo[b,d]furan (1). 1-(Dibenzo[b,d]furan-4-yl)-1H-
1,2,4-triazole (2) was obtained by a copper-catalyzed coupling
reaction of 1 with 1H-1,2,4-triazole. Subsequent quaternization
using iodomethane gave the ligand precursor 3. In contrast, the
synthesis of 1-(dibenzo[b,d]furan-2-yl)-4-methyl-1,2,4-triazo-
lium iodide (6) started with iodination of DBF using
benzyltrimethylammonium dichloroiodate. The following
steps to obtain 6 are the same as those for the preparation of 3.
Three β-diketonato auxiliary ligands (acetylacetonato,
dibenzoylmethanato, and dimesitoylmethanato) with varying
steric demands were selected to investigate their influence on
the photoluminescence properties of the emitters. All
complexes were synthesized according to a modified synthetic
procedure for C∧C* cyclometalated platinum(II) complexes
(Scheme 2).30 The ligand precursors 3 and 6 were
All complexes were characterized by NMR spectroscopy and
1
elemental analysis. The absence of a proton signal in the H
NMR revealed the formation of a carbene carbon. Signals of the
carbene carbons were found for 7−9 and 11,12 between 150.5
and 154.3 ppm in the 13C NMR spectra. Due to the low
solubility of 10, a respective 13C resonance for the carbene
carbon could not be identified. Cyclometalation through the C3
atom of the DBF unit was confirmed by the coupling pattern
1
observed from H NMR, COSY, and NOESY experiments. In
principle, it would also be possible that a five-membered
metallacycle via the DBF-C1 atom is formed for 10−12 but was
not observed. In all spectra we detected a singlet proton signal,
which could be assigned to the aromatic C1H group of the
1
DBF unit by a H−13C HSQC experiment. 195Pt NMR spectra
revealed signals that are characteristic for this class of
platinum(II) triazolylidene complexes in the range of −3345
to −3426 ppm.
Single crystals suitable for X-ray diffraction could be obtained
of 8 (Figure 1) and 11 (Figure 2) by slow vapor diffusion of
diethyl ether into highly concentrated solutions of the
Scheme 2. Complexes 7−12
Figure 1. Solid-state structure of 8. Thermal ellipsoids are drawn at the
50% probability level. Selected bond distances (Å) and angles (deg):
Pt(1)−C(1) 1.944(19), Pt(1)−C(5) 2.02(3), Pt(1)−O(1) 2.116(16),
Pt(1)−O(2) 2.050(11); C(1)−Pt(1)−C(5) 80.9(9), C(1)−Pt(1)−
O(1) 98.5(7), C(5)−Pt(1)−O(2) 91.0(7), O(1)−Pt(1)−O(2)
89.5(5), C(5)−Pt(1)−C(1)-N(2) −180(2), O(1)−Pt(1)−C(1)−
N(1) −179.1(14), O(2)−Pt(1)−O(1)−C(16) 3.3(12).
deprotonated with silver(I) oxide to form a silver(I) carbene
complex. Transmetalation with dichloro(cycloocta-1,5-diene)-
platinum(II) was followed by cyclometalation at elevated
temperatures. The complexes 7−9 and 10−12 were then
obtained by reaction with the respective β-diketone in the
presence of potassium tert-butoxide. Thus, the complexes 7−9,
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Figure 4. Emission spectra of 7−12 (2 wt % in PMMA) at room
temperature.
Figure 2. Solid-state structure of 11. Thermal ellipsoids are drawn at
the 50% probability level. Selected bond distances (Å) and angles
(deg): Pt(1)−C(1) 1.931(7), Pt(1)−C(5) 2.001(7), Pt(1)−O(1)
2.083(4), Pt(1)−O(2) 2.050(4); C(1)−Pt(1)−C(5) 80.0(3), C(1)−
Pt(1)−O(1) 97.2(2), C(5)−Pt(1)−O(2) 92.4(2), O(1)−Pt(1)−O(2)
90.30(16), C(5)−Pt(1)−C(1)−N(2) 178(9), O(1)−Pt(1)−C(1)−
N(1) 172.9(5), O(2)−Pt(1)−O(1)−C(16) 5.9(5).
All complexes are strongly emissive at room temperature,
with emission properties depending on the β-diketonato
auxiliary ligand as well as on the cyclometalating DBF-NHC
ligand (Table 1). Complexes 8 and 11, with a dibenzoyl-
Table 1. Photoluminescent Data of 7−12 (2 wt % in PMMA)
at Room Temperature
complexes in dichloromethane. Details of the structure
determination are given in Table S1 in the Supporting
Information. Both complexes crystallize in the monoclinic
space group P21/c without any solvent molecules, and their
solid-state structures exhibit a quasi square-planar coordination
environment. As in similar complexes of the type [Pt(C∧C*)-
(O∧O)]37,42 the ideal value of 90° is nearly retained for the
O1−Pt1−O2 angles of 8 (89.5°) and 11 (90.3°), whereas the
C1−Pt1−C5 angle is significantly smaller (8, 80.9°; 11, 80.0°).
Pt1−C1 and Pt1−C5 bond lengths also lie in the range of
similar complexes. The Pt1−O1 bonds of both complexes are
slightly elongated in comparison to the Pt1−O2 bonds due to
the trans influence of the DBF unit. The phenyl rings of the β-
diketonato auxiliary ligand are significantly rotated into the
coordination plane and therefore support molecular stacking of
the complexes (see Figures S1 and S2 in the Supporting
Information).
a
b
c
d
e
λexc (nm)
CIE x; y
λem (nm)
Φ
τ0 (μs)
7
370
360
355
330
370
340
0.196; 0.431
0.337; 0.556
0.184; 0.419
0.154; 0.185
0.331; 0.560
474, 506, 542
526
0.70
0.41
0.76
0.71
0.45
0.87
26
6
8
9
473, 505, 541
446, 474
524
26
24
7
10
11
12
0.173; 0.259
445, 474
10
a
b
Excitation wavelength. CIE coordinates at room temperature.
c
d
Maximum emission wavelength. Quantum yield at λexc, N2
e
atmosphere. Decay lifetimes (excited by laser pulses (355 nm, 1
ns)) given as τo = τv/ϕ.
methanato auxiliary ligand, exhibit emission bands with only
one maximum in the green region of the spectrum and
quantum efficiencies between 41% and 45%. In contrast to the
case for 8 and 11, all other complexes were found to be efficient
blue emitters, showing quantum efficiencies between 70% and
87% (12). The PL spectra of these complexes display
structured emission profiles with vibronic progressions of
1318−1340 cm−1. The first report on C∧C*-cyclometalated
triazole complexes37 demonstrated that the complexes based on
1-aryl-1H-1,2,4-triazole showed significantly better quantum
yields (30−41%) in comparison to those based on 4-aryl-4H-
1,2,4-triazole (11−14%), depending on the substitution in the
para position of the phenyl unit. Therefore, we decided to
concentrate on the more promising isomer in combination with
the extended π system of the dibenzofuran. The quantum yield
increased significantly to 70%, but unfortunately the decay time
also increased in comparison to those for the first triazole-based
examples.37 As we had observed a significant effect of the
dimesitoylmethanato ligand for the imidazolium-based com-
plexes,39 which led to an increase in the quantum yield together
with a shorter decay time, we investigated the effect of this
ligand on the parent triazole complexes. Unfortunately the
complexes based on triazolium salt and imidazolium salts differ
in their photophysics; we found the expected behavior only for
12, not for the regular isomer 9.
Photophysical Properties. All complexes were examined
in terms of their photophysical properties from amorphous
films of 2 wt % emitter in poly(methyl methacrylate) (PMMA).
Absorption spectra (Figure 3) and emission spectra (Figure 4)
were measured at room temperature.
Figure 3. Absorption spectra of 7−12 (2 wt % in PMMA) at room
temperature.
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A blue shift of the emission wavelength of 10 and 12 by
about 30 nm in comparison to 7 and 9 shows the influence of
the DBF bonding positions on the emission wavelength. The
emission properties of complexes 9 and 12, with a
dimesitoylmethanato ligand, also significantly differ from each
other. In contrast to the case for 9, complex 12 reveals a less
structured emission band and an increased quantum efficiency
of 87%. To investigate the effect of interactions between the
complexes on their photoluminescence properties, emission
spectra of neat emitter films of 7−9, 11, and 12 were measured;
of these, 8, 9, and 11 are not emissive (see Figures S3−S6 and
Table S2 in the Supporting Information). A neat film of 10
could not be obtained, due to crystallization of the emitter
during film preparation. Complex 7 shows a low-energy
emission of a multimolecular complex species at 612 nm with
a quantum efficiency of 4%. It is important to note that the
planar structure of the complex supports molecular stacking.
However, shielding of the platinum center by a sterically
demanding dimesitoylmethanato ligand may efficiently sup-
press molecular stacking, as can be seen from the PL spectra of
12. The neat emitter film reveals an emission profile similar to
that of 2 wt % of the complex in a PMMA matrix, which proves
that 12 exists as a monomeric species even at high emitter
concentrations.
Figure 6. Optimized ground-state geometries (B3LYP/6-31G(d)) of
the DBF-C1 cyclometalated complex 10 (left) and the related DBF-C1
cyclometalated isomer (right).
thermodynamically more favored than their DBF-C1 cyclo-
metalated analogues by 6.2 (10), 6.3 (11), and 6.1 kcal mol−1
(12).
CONCLUSION
■
Two series of new platinum(II) NHC complexes [Pt(C∧C*)-
(O∧O)] with C∧C* cyclometalating 1-(dibenzo[b,d]furan-4-
yl)-4-methyl-1,2,4-triazol-5-ylidene ligands (O∧O = acetylace-
tonato (7), dibenzoylmethanato (8), dimesitoylmethanato (9))
and 1-(dibenzo[b,d]furan-2-yl)-4-methyl-1,2,4-triazol-5-ylidene
ligand (O∧O = acetylacetonato (10), dibenzoylmethanato (11),
dimesitoylmethanato (12)) were successfully synthesized and
characterized. The structures of 8 and 11 were additionally
determined by X-ray crystallography. All complexes are strongly
phosphorescent at room temperature in a PMMA film in the
green (8 and 11) and blue regions of the visual spectrum (7, 9,
10, and 12). The 1-(dibenzo[b,d]furan-2-yl)-4-methyl-1,2,4-
triazol-5-ylidene ligand shifts the emission wavelengths of 10
and 12 to higher energies by about 30 nm and increases the
quantum yield in comparison to 7 and 9. The highest quantum
efficiency of 87% was found for 12.
DFT Calculations. DFT calculations were performed to get
an insight into the emission process of all the complexes and to
understand the selectivity in the cyclometalation position of the
complexes 10−12. The ground-state geometries of all
complexes were optimized in the gas phase on B3LYP/6-
31G(d) level with Hay−Wadt ECP for platinum. The
optimized structures obtained for 8 and 11 are in good
agreement with the structural data determined by X-ray
crystallography.
To shed light on the emission process, the Kohn−Sham
orbitals (HOMO-2 to LUMO+2) of the ground states were
computed for all complexes (see Figure 5 and Figures S7−S12
EXPERIMENTAL DETAILS
■
General Considerations. DMF and 1,4-dioxane were dried by
using standard procedures and stored over molecular sieves (4 Å)
under an argon atmosphere. Potassium tetrachloroplatinate(II) was
purchased from Pressure Chemicals Co. Other reagents and solvents
were used as received from commercial suppliers. Benzyltrimethy-
lammonium dichloroiodate,43 4-bromodibenzo[b,d]furan,30 and dime-
sitoylmethane44 were synthesized according to reported procedures.
Dichloro(cycloocta-1,5-diene)platinum(II)45 was prepared following a
modified literature procedure.30 NMR spectra were recorded on a
Bruker NMR spectrometer. The NMR chemical shifts (δ) are given in
ppm and referenced to residual solvents: CDCl3 (1H, 7.26 ppm; 13C,
77.0 ppm) and DMSO-d6 (1H, 2.50 ppm; 13C, 39.4 ppm). The 195Pt
NMR shifts are referenced to potassium tetrachloroplatinate(II) as an
external standard ([PtCl4]2−, −1617.2 ppm; [PtCl2], −2654.1 ppm).
The coupling constants (J) are given in Hz, and the signal splitting is
abbreviated as follows: s = singlet, d = doublet, t = triplet, m =
multiplet. Elemental analyses were performed on a Hekatech
elemental analyzer by the microanalytical laboratory of our institute.
Melting points were measured on a Wagner and Munz Poly Therm A
system and were not corrected. Emitter films used for PL
measurements were prepared by doctor-blading a solution of the
emitter (2 mg/mL) in a 10 wt % PMMA solution in dichloromethane
on a substrate with a 60 μm doctor blade. The excitation was carried
out at a wavelength of 330−370 nm (Xe lamp with monochromator),
and the emission was detected with a calibrated quantum-yield
detection system (Hamamatsu, Model C9920-02). The phosphor-
escence decay was measured by excitation with pulses of a THG-
NdYAG laser (355 nm, 1 ns) and time-resolved photon counting by
multichannel scaling (MCS) techniques.
Figure 5. HOMO, LUMO, and LUMO+1 plots of 7 (B3LYP/6-
31G(d), isovalue 0.02).
in the Supporting Information). A comparison of the frontier
molecular orbitals (FMOs) of 7 indicates a strong contribution
of a ligand-centered state (LC) in the DBF unit with an
admixture of a metal to ligand charge transfer (MLCT), which
is in agreement with the intensely structured emission band of
7. The LUMO of all other complexes is mostly located on the
O∧O ligand.
The geometries of the isomers with a cyclometalated DBF-
C1 atom were also optimized to get an insight into the
selectivity of the cyclometalating position for 10−12. In
contrast to the case for complexes 10−12, the DBF units of
the DBF-C1 cyclometalated isomers are significantly bent due
to steric crowding (see Figure 6 and Figure S13 and S14 in the
Supporting Information), which leads to an inconvenient
distortion of the cyclometalating ring. A comparison of the free
energies reveals that the DBF-C3 cyclometalated complexes are
General Procedure for Complex Synthesis. A Schlenk tube was
charged with triazolium salt, silver(I) oxide, and dry 1,4-dioxane. The
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mixture was stirred for 21 h at room temperature under a positive
pressure of argon. Afterward, dichloro(cycloocta-1,5-diene)platinum-
(II) and dry butanone were added and the mixture was stirred for 3 h
at room temperature and another 21 h at 100 °C. After the mixture
was cooled to ambient temperature, the solvents were removed in
vacuo. Potassium tert-butoxide, β-diketone, and dry DMF were added
to the remaining solid, and the mixture was stirred for 21 h at room
temperature and then heated to 100 °C for 6 h. Afterward, all volatile
components were removed under reduced pressure and the solid
residue was washed with water and dried at 60 °C. The crude product
was then purified by column chromatography, washed with isohexanes,
and dried in vacuo.
respectively. The collected organic phase was dried with sodium
sulfate, and the solvent was removed under reduced pressure. Drying
in vacuo afforded 2.01 g of a 2-iododibenzo[b,d]furan/dibenzo[b,d]-
furan mixture as a yellow solid (ratio 1:1.9, yield of 4 33%). The
product was used for the synthesis of 5 without further purification. 1H
NMR (300.13 MHz, DMSO-d6): δ 8.21 (d, JHH = 1.8 Hz, 1 H,
CHarom); 7.84 (d, 3JHH = 8.2 Hz, 1 H, CHarom); 7.66 (dd, JHH = 1.8 Hz,
3
3JHH = 8.6 Hz, 1 H, CHarom); 7.50 (d, JHH = 8.3 Hz, 1 H, CHarom),
7.42 (dt, JHH = 1.3 Hz, 3JHH = 7.2 Hz, 1 H, CHarom); 7.33−7.22 (m, 2
H, CHarom) ppm. MS (GC-MS): m/z (%) 294 (M+), 167 (M+ − I),
139 (M+ − I − CO).
Synthesis of 1-(Dibenzo[b,d]furan-2-yl)-1H-1,2,4-triazole (5).
A Schlenk tube was charged with 2013 mg of the 2-iododibenzo-
[b,d]furan/dibenzo[b,d]furan mixture (34 mol % of 2-iododibenzo-
[b,d]furan 4: 3.3 mmol), 271 mg of 1H-1,2,4-triazole (3.9 mmol, 1.2
equiv), 904 mg of potassium carbonate (6.6 mmol, 2.0 equiv), 3 mg of
copper(I) iodide (5 mol %), and 2 mg of hexamethylenetetramine (5
mol %). A 40 mL portion of dry DMF was added, and the mixture was
stirred for 48 h at 130 °C under an argon atmosphere. After it was
cooled to room temperature, the mixture was filtered over a plug of
Celite and rinsed with 100 mL of ethyl acetate. The filtrate was washed
three times with 100 mL of water, respectively, and once with 100 mL
of brine. The organic phase was then dried over sodium sulfate, all
volatiles were removed under reduced pressure, and the solid residue
was purified by column chromatography (KG60, ethyl acetate). After
recrystallization from ethanol the product was obtained as 258 mg of a
Synthesis of 1-(Dibenzo[b,d]furan-4-yl)-1H-1,2,4-triazole (2).
A Schlenk tube was charged with 9.88 g of 4-bromodibenzofuran (1;
40.0 mmol), 3.32 g of 1H-1,2,4-triazole (1.2 equiv, 48.0 mmol), 11.06
g of potassium carbonate (2 equiv, 80.0 mmol), 0.57 g of copper(I)
iodide (10 mol %, 4.0 mmol) and 0.56 g of hexamethylenetetramine
(10 mol %, 4.0 mmol). A 40 mL portion of dry DMF was added, and
the mixture was stirred for 72 h at 150 °C under an argon atmosphere.
After it was cooled to room temperature, the mixture was filtered
through a plug of Celite and rinsed with 100 mL of dichloromethane.
The filtrate was washed three times with 100 mL of water, respectively,
and once with 100 mL of brine. The organic phase was then dried over
sodium sulfate, all volatiles were removed under reduced pressure, and
the remaining solid was purified by column chromatography (KG60,
ethyl acetate/isohexanes solvent mixture (1/1)). After recrystallization
from ethanol the product was obtained as 2.25 g of a yellow solid
1
yellow solid (34%). Mp: 115 °C. H NMR (500.13 MHz, CDCl3): δ
1
(24%). Mp: 72 °C. H NMR (500.13 MHz, CDCl3): δ 9.28 (s, 1 H,
8.66 (s, 1 H, NCHN); 8.26 (d, JHH = 2.2 Hz, 1 H, CHarom); 8.17 (s, 1
H, NCHN); 8.00 (d, 3JHH = 7.8 Hz, 1 H, CHarom); 7.74 (dd, JHH = 2.3
Hz, 3JHH = 8.7 Hz, 1 H, CHarom); 7.68 (d, 3JHH = 8.8 Hz, 1 H, CHarom);
NCHN); 8.19 (s, 1 H, NCHN); 8.05 (dd, 3JHH = 8.0 Hz, JHH = 1.0 Hz,
3
1 H, CHarom); 8.00 (d, 3JHH = 7.6 Hz, 1 H, CHarom); 7.94 (dd, JHH
=
3
3
4
3
7.7 Hz, JHH = 1.0 Hz, 1 H, CHarom); 7.86 (d, JHH = 8.3 Hz, 1 H,
CHarom); 7.73 (dt, JHH = 1.3 Hz, 3JHH = 7.8 Hz, 1 H, CHarom); 7.48 (t,
3JHH = 7.8 Hz, 1 H, CHarom), 7.42 (t, 3JHH = 7.5 Hz, 1 H, CHarom) ppm.
13C NMR (125.77 MHz, CDCl3): δ 156.2 (Carom); 152.0 (NCHN);
7.62 (d, JHH = 8.3 Hz, 1 H, CHarom), 7.53 (dt, JHH = 1.3 Hz, JHH
=
4
3
7.8 Hz, 1 H, CHarom), 7.40 (dt, JHH = 0.8 Hz, JHH = 7.5 Hz, 1 H,
CHarom) ppm. 13C NMR (125.77 MHz, CDCl3): δ 157.1 (Carom);
155.4 (Carom); 152.4 (NCHN); 141.1 (NCHN); 132.5 (Carom); 128.3
(CHarom); 125.5 (Carom); 123.5 (Carom); 123.3 (CHarom); 121.1
(CHarom); 119.6 (CHarom); 113.1 (CHarom); 112.7 (CHarom); 112.1
(CHarom) ppm. Anal. Calcd for C14H9N3O·0.1H2O: C, 70.94; H, 3.91;
N, 17.73. Found: C, 70.91; H, 3.75; N, 17.81.
145.6 (Carom); 143.9 (NCHN); 128.2 (CHarom); 126.5 (Carom); 123.8
(CHarom); 123.7 (CHarom); 123.5 (Carom); 122.3 (Carom); 121.0
(CHarom); 119.7 (CHarom); 119.0 (CHarom); 112.0 (CHarom) ppm.
Anal. Calcd for C14H9N3O: C, 71.48; H, 3.86; N, 17.86. Found: C,
71.15; H, 3.82; N, 17.96.
Synthesis of 1-(Dibenzo[b,d]furan-2-yl)-4-methyl-1H-1,2,4-
triazolium Iodide (6). A pressure tube was charged with 1.88 g of
triazole 5 (8.0 mmol) and 8 mL of THF. A 1.01 mL portion of
iodomethane (2.29 g, 16 mmol, 2.0 equiv) was added, the pressure
tube was sealed, and the reaction mixture was stirred for 21 h at 110
°C. After the mixture was cooled to room temperature, the obtained
solid was filtered, washed with THF, and dried in vacuo to yield 2.50 g
Synthesis of 1-(Dibenzo[b,d]furan-4-yl)-4-methyl-1H-1,2,4-
triazolium Iodide (3). A pressure tube was charged with 1.88 g of
triazole 2 (8.0 mmol) and 10 mL of THF. A 1.01 mL portion of
iodomethane (2.29 g, 16.0 mmol, 2 equiv) was added, the pressure
tube was sealed, and the reaction mixture was stirred for 24 h at 110
°C. After the mixture was cooled to room temperature, the obtained
solid was filtered, washed with THF, and dried in vacuo to yield 2.73 g
1
of the product as a white powder (83%). Mp: 232 °C. H NMR
1
of the product as a yellow powder (90%). Mp: 210 °C. H NMR
(300.13 MHz, CDCl3): δ 10.90 (s, 1 H, NCHN); 9.44 (s, 1 H,
NCHN); 8.76 (s, 1 H, CHarom); 8.30 (d, 3JHH = 7.7 Hz, 1 H, CHarom);
(500.13 MHz, DMSO-d6): δ 10.99 (s, 1 H, NCHN); 9.52 (s, 1 H,
NCHN); 8.45 (dd, JHH = 1.0 Hz, 3JHH = 7.8 Hz, 1 H, CHarom); 8.30 (d,
3JHH = 7.8 Hz, 1 H, CHarom); 8.07 (dd, JHH = 0.9 Hz, 3JHH = 8.0 Hz, 1
3
8.10−8.03 (m, 2 H, CHarom); 7.84 (d, JHH = 8.3 Hz, 1 H, CHarom);
3
3
7.67 (t, JHH = 7.8 Hz, 1 H, CHarom), 7.52 (t, JHH = 7.5 Hz, 1 H,
CHarom), 4.04 (s, 3 H, CH3) ppm. 13C NMR (125.77 MHz, CDCl3): δ
156.5 (CO); 155.6 (CO); 145.9 (NCHN); 142.3 (NCHN); 130.7
(Carom); 129.1 (Carom); 124.8 (Carom); 124.0 (Carom); 122.7 (Carom);
121.8 (Carom); 120.5 (Carom); 114.4 (Carom); 113.3 (Carom); 112.2
(Carom); 34.4 (CH3) ppm. Anal. Calcd for C15H12IN3O: C, 47.77; H
3.21; N 11.14. Found: C, 47.50; H, 3.26; N, 11.49.
3
3
H, CHarom); 7.84 (d, JHH = 8.3 Hz, 1 H, CHarom); 7.71 (t, JHH = 7.9
4
3
Hz, 1 H, CHarom); 7.48 (dt, JHH = 1.3 Hz, JHH = 7.8 Hz, 1 H,
CHarom), 7.42 (dt, 4JHH = 0.7 Hz, 3JHH = 7.5 Hz, 1 H, CHarom), 4.40 (s,
3 H, CH3) ppm. 13C NMR (125.77 MHz, DMSO-d6): δ 155.7 (Carom);
145.9 (NCHN) 145.6 (Carom); 144.0 (NCHN); 129.1 (CHarom); 126.4
(Carom); 124.4 (CHarom); 124.3 (CHarom); 123.4 (CHarom); 122.6
(Carom); 122.1 (CHarom); 120.4 (CHarom); 120.0 (Carom); 112.1
(CHarom) 34.9 (CH3) ppm. Anal. Calcd for C15H12IN3O: C, 47.77;
H, 3.21; N, 11.14. Found: C, 47.50; H, 3.00; N, 11.05.
Synthesis of (1-(Dibenzo[b,d]furan-4-yl)-κC3-4-methyl-1,2,4-
triazol-5-ylidene-κC5)(pentane-2,4-dionato-κ2O,O)platinum(II)
(7). Compound 7 was synthesized according to the general procedure
using 603 mg of the triazolium salt 3 (1.6 mmol), 185 mg of silver(I)
oxide (0.8 mmol, 0.5 equiv), 599 mg of dichloro(cycloocta-1,5-
diene)platinum(II) (1.6 mmol, 1.0 equiv), 718 mg of potassium tert-
butoxide (6.4 mmol, 4.0 equiv), 641 mg of pentane-2,4-dione (6.4
mmol, 4.0 equiv), 40 mL of dry 1,4-dioxane, 20 mL of dry butanone,
and 40 mL of dry DMF. The product was purified by column
chromatography (KG60, dichloromethane), washed with isohexanes,
and dried in vacuo to yield 150 mg of a yellow powder (17%).
Decomposition occurred above 250 °C. 1H NMR (300.13 MHz,
Synthesis of 2-Iododibenzo[b,d]furan (4). In a round-bottom
flask fitted with a reflux condenser 1.68 g of dibenzo[b,d]furan (10.0
mmol) was dissolved in 100 mL of acetic acid. A 4.17 g portion of
benzyltrimethylammonium dichloroiodate (12.0 mmol, 1.2 equiv) and
1.64 g of zinc chloride (12.0 mmol, 1.2 equiv) were added, and the
reaction mixture was stirred at 75 °C. After 24 h, another 4.17 g of
benzyltrimethylammonium dichloroiodate (12.0 mmol, 1.2 equiv) was
added and the mixture was stirred for another 24 h at 75 °C. After the
mixture was cooled to room temperature, 100 mL of water and 24 mL
of a sodium bisulfite solution (5% in water) were added and the water
phase was extracted three times with 100 mL of dichloromethane,
3
CDCl3): δ 8.04 (s, 1 H, NCHN); 7.94 (dd, JHH = 1.1 Hz, JHH = 7.5
Hz, 1 H, CHarom); 7.83 (d, 3JHH = 7.8 Hz, 1 H, CHarom); 7.70−7.65 (m,
E
DOI: 10.1021/acs.organomet.5b00136
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
4
3
2 H, CHa4rom); 7.42 (dt, JHH = 1.1 Hz, JHH = 7.4 Hz, 1 H, CHarom);
(CHarom); 128.1 (CHarom); 126.5 (CHarom); 125.8 (CHarom); 124.6
(Carom); 123.5 (Carom); 122.8 (CHarom); 121.7 (Carom); 120.1 (CHarom);
116.9 (CHarom); 111.8 (CHarom); 107.3 ((CO)CH(CO)); 32.9 (CH3);
21.1 (CH3); 21.1 (CH3); 19.9 (CH3); 19.5 (CH3) ppm. 195Pt NMR
(64.33 MHz, CDCl3): δ −3381 ppm. Anal. Calcd for C36H33N3O3Pt·
0.4CH2Cl2: C, 55.71; H, 4.34; N, 5.35. Found: C, 55.76; H, 4.44; N,
5.45.
3
7.33 (dt, JHH = 0.9 Hz, JHH = 7.4 Hz, 1 H, CHarom); 5.56 (s, 1 H,
(CO)CH(CO)); 4.16 (s, 3 H, CH3); 2.14 (s, 3 H, CH3); 2.01 (s, 3 H,
CH3) ppm. 13C NMR (150.93 MHz, CDCl3): δ 185.2 (CO); 156.1
(CO); 154.3 (NCN); 142.6 (Carom); 142.3 (NCHN); 128.8 (Carom);
126.5 (CHarom); 125.4 (CHarom); 124.6 (Carom); 123.3 (Carom); 122.8
(CHarom); 122.1 (Carom); 120.1 (CHarom); 116.8 (CHarom); 111.9
(CHarom); 102.2 ((CO)CH(CO)); 32.8 (NCH3); 27.9 (CCH3) ppm.
Signals for one CO and one CCH3 were not observed in the 13C NMR
spectrum. 195Pt NMR (128.56 MHz, CDCl3): δ −3426 ppm. Anal.
Calcd for C20H17N3O3Pt: C, 44.28; H, 3.16; N, 7.75. Found: C, 44.27;
H, 3.28; N, 7.40.
Synthesis of (1-(Dibenzo[b,d]furan-2-yl)-κC3-4-methyl-1,2,4-
triazol-5-ylidene-κC5)(pentane-1,3-dionato-κ2O,O)platinum(II)
(10). Compound 10 was synthesized according to the general
procedure using 278 mg of the triazolium salt 6 (0.74 mmol), 85
mg of silver(I) oxide (0.37 mmol, 0.5 equiv), 276 mg of
dichloro(cycloocta-1,5-diene)platinum(II) (0.74 mmol, 1.0 equiv),
331 mg of potassium tert-butoxide (2.97 mmol, 4.0 equiv), 295 mg of
pentane-2,4-dione (2.97 mmol, 4.0 equiv), 40 mL of dry 1,4-dioxane,
20 mL of dry butanone, and 40 mL of dry DMF. The product was
purified by column chromatography (KG60, dichloromethane),
washed with isohexanes, and dried in vacuo to yield 29 mg of a
yellow powder (7%). Decomposition occurred above 250 °C. 1H
NMR (300.13 MHz, CDCl3): δ 7.97−7.75 (m, 4 H, NCHN and
CHarom); 7.48 (d, 3JHH = 8.3 Hz, 1 H, CHarom); 7.34 (dt, 4JHH = 1.3 Hz,
3JHH = 7.7 Hz, 1 H, CHarom); 7.24 (t, 3JHH = 7.8 Hz, 1 H, CHarom); 5.50
(s, 1 H, (CO)CH(CO)); 4.05 (s, 3 H, CH3); 2.08 (s, 3 H, CH3); 1.94
(s, 3 H, CH3) ppm. 13C NMR (125.77 MHz, CDCl3): δ 156.0 (CO);
152.7 (CO); 141.0 (CHarom); 125.9 (CHarom); 125.3 (Carom); 122.4
(CHarom); 119.8 (CHarom); 119.6 (Carom); 114.1 (CHarom); 111.6
(CHarom); 102.2 (CH); 32.8 (CH3); 27.8 (CH3) ppm. Signals for two
CO, the NCN, one CH3, two Carom, and one CH were not observed in
the 13C NMR spectrum. 195Pt NMR (64.33 MHz, CDCl3): δ −3410
ppm. Anal. Calcd for C20H17N3O3Pt·0.25CH2Cl2: C, 43.15; H, 3.13;
N, 7.45. Found: C, 43.13; H, 2.95; N, 7.54.
Synthesis of (1-(Dibenzo[b,d]furan-4-yl)-κC3-4-methyl-1,2,4-
triazol-5-ylidene-κC5)(1,3-diphenylpropane-1,3-dionato-
κ2O,O)platinum(II) (8). A Schlenk tube was charged with 603 mg of
triazolium salt 3 (1.6 mmol), 185 mg of silver(I) oxide (0.8 mmol, 0.5
equiv), and 40 mL of dry DMF. The mixture was stirred for 21 h at 60
°C under an argon atmosphere. A 599 mg portion of dichloro-
(cycloocta-1,5-diene)platinum(II) (1.6 mmol, 1.0 equiv) was added,
and the mixture was stirred for 3 h at room temperature and another
21 h at 140 °C. After the mixture was cooled to room temperature,
718 mg of potassium tert-butoxide (6.4 mmol, 4.0 equiv) and 1465 mg
of dibenzoylmethane (6.4 mmol, 4.0 equiv) were added and the
mixture was stirred for 21 h at room temperature and then heated to
100 °C for 6 h. Afterward, all volatile components were removed
under reduced pressure and the remaining solid was washed with
water and dried at 60 °C. The crude product was purified by column
chromatography (KG60, dichloromethane), washed with isohexanes,
and dried in vacuo to yield 202 mg of a yellow powder (19%).
Decomposition occurred above 250 °C. 1H NMR (600.16 MHz,
3
DMSO-d6): δ 8.93 (s, 1 H, NCHN); 8.28 (d, JHH = 7.2 Hz, 2 H,
CHarom); 8.14 (d, 3JHH = 8.2 Hz, 2 H, CHarom); 8.10 (d, 3JHH = 7.5 Hz,
Synthesis of (1-(Dibenzo[b,d]furan-2-yl)-κC3-4-methyl-1,2,4-
triazol-5-ylidene-κC5)(1,3-diphenylpropane-1,3-dionato-
κ2O,O)platinum(II) (11). Compound 11 was synthesized according
to the general procedure using 603 mg of the triazolium salt 6 (1.6
mmol), 185 mg of silver(I) oxide (0.8 mmol, 0.5 equiv), 599 mg of
dichloro(cycloocta-1,5-diene)platinum(II) (1.6 mmol, 1.0 equiv), 359
mg of potassium tert-butoxide (3.2 mmol, 2.0 equiv), 732 mg of
dibenzoylmethane (3.2 mmol, 2.0 equiv), 40 mL of dry 1,4-dioxane, 20
mL of dry butanone, and 40 mL of dry DMF. The product was
purified by column chromatography (KG60, dichloromethane),
washed with isohexanes, and dried in vacuo to yield 248 mg of a
yellow powder (23%). Mp: 309 °C. 1H NMR (600.16 MHz, CDCl3):
δ 8.85 (s, 1 H, NCHN); 8.27 (d, 3JHH = 8.0 Hz, 2 H, CHarom); 8.18 (d,
1 H, CHarom); 7.95−7.90 (m, 2 H, CHarom); 7.74 (d, 3JHH = 8.1 Hz, 1
3
3
H; CHarom); 7.69 (t, JHH = 7.3 Hz, 1 H, CHarom); 7.65 (t, JHH = 7.4
Hz, 1 H, CHarom); 7.62 (t, 3JHH = 7.6 Hz, 2 H, CHarom); 7.55 (t, 3JHH
=
4
3
7.7 Hz, 2 H, CHarom); 7.52 (dt, JHH = 1.7 Hz, JHH = 7.7 Hz, 1 H,
CHarom); 7.41 (t, JHH = 7.5 Hz, 1 H, CHarom); 7.05 (s, 1 H,
3
(CO)CH(CO)); 4.23 (s, 3 H; CH3) ppm. 13C NMR (150.93 MHz,
DMSO-d6): δ 180.2 (CO); 178.6 (CO); 157.8 (CO); 151.1 (NCN);
144.8 (NCHN); 141.7 (Carom); 139.6 (Carom); 138.7 (Carom); 131.67
(CHarom); 131.5 (CHarom); 129.0 (CHarom); 129.0 (CHarom); 127.3
(CHarom); 127.3 (CHarom); 127.2 (CHarom); 125.4 (CHarom); 124.0
(Carom); 123.3 (CHarom); 122.7 (Carom); 120.6 (CHarom); 116.8
(CHarom); 111.6 (CHarom); 96.6 ((CO)CH(CO)); 33.0 (CH3) ppm.
Signals for two Carom were not observed in the 13C NMR spectrum.
195Pt NMR (128.56 MHz, CDCl3): δ −3369 ppm. Anal. Calcd for
3
3JHH = 7.6 Hz, 1 H, CHarom); 8.12 (d, JHH = 8.0 Hz, 2 H, CHarom);
8.03 (s, 1 H; CHarom); 7.96 (s, 1 H; CHarom); 7.75−7.60 (m, 5 H,
CHarom); 7.54 (t, 3JHH = 7.4 Hz, 2 H, CHarom); 7.48 (t, 3JHH = 7.71 Hz,
C30H21N3O3Pt: C, 54.06; H, 3.18; N, 6.30. Found: C, 53.69; H, 3.31;
N, 6.29.
3
1 H, CHarom); 7.36 (t, JHH = 7.41 Hz, 1 H, CHarom); 7.02 (s, 1 H,
Synthesis of (1-(Dibenzo[b,d]furan-4-yl)-κC3-4-methyl-1,2,4-
triazol-5-ylidene-κC5)(1,3-bis(2,4,6-trimethylphenyl)propane-
1,3-dionato-κ2O,O)platinum(II) (9). Compound 9 was synthesized
according to the general procedure using 603 mg of the triazolium salt
3 (1.6 mmol), 185 mg of silver(I) oxide (0.8 mmol, 0.5 equiv), 599 mg
of dichloro(cycloocta-1,5-diene)platinum(II) (1.6 mmol, 1 equiv), 359
mg of potassium tert-butoxide (3.2 mmol, 2.0 equiv), 987 mg of
dimesitoylmethane (3.2 mmol, 2.0 equiv), 40 mL of dry 1,4-dioxane,
20 mL of dry butanone, and 40 mL of dry DMF. The product was
purified by column chromatography (KG60, dichloromethane/
isohexanes solvent mixture (1/1)), washed with isohexanes, and
dried in vacuo to yield 261 mg of a yellow powder (22%). Mp: 218 °C.
1H NMR (600.16 MHz, CDCl3): δ 8.02 (s, 1 H, NCHN); 7.89 (d,
(CO)CH(CO)); 4.17 (s, 3 H; CH3) ppm. 13C NMR (150.93 MHz,
CDCl3): δ 180.1 (CO); 178.6 (CO); 155.3 (CO); 153.1 (CO); 150.5
(NCN); 144.4 (NCHN); 141.1 (Carom); 139.6 (Carom); 138.7 (Carom);
131.7 (CHarom); 131.5 (CHarom phenyl); 129.1 (CHarom); 128.9
(CHarom); 127.3 (CHarom); 127.2 (CHarom); 126.5 (CHarom); 124.6
(Carom); 123.8 (Carom); 122.9 (CHarom); 120.7 (CHarom); 119.2 (Carom);
113.4 (CHarom); 111.6 (CHarom); 103.9 (CHarom); 96.7 ((CO)
CH(CO)); 33.0 (CH3). 195Pt NMR (128.63 MHz, CDCl3): δ
−3345 ppm. Anal. Calcd for C30H21N3O3Pt: C, 54.06; H, 3.18; N,
6.30. Found: C, 53.68; H, 3.05; N, 6.13.
Synthesis of (1-(Dibenzo[b,d]furan-2-yl)-κC3-4-methyl-1,2,4-
triazol-5-ylidene-κC5)(1,3-bis(2,4,6-trimethylphenyl)propane-
1,3-dionato-κ2O,O)platinum(II) (12). Compound 12 was synthe-
sized according to the general procedure using 220 mg of the
triazolium salt 6 (0.58 mmol), 50 mg of silver(I) oxide (0.29 mmol,
0.5 equiv), 327 mg of dichloro(cycloocta-1,5-diene)platinum(II) (0.87
mmol, 1.5 equiv), 262 mg of potassium tert-butoxide (2.33 mmol, 4.0
equiv), 720 mg of dimesitoylmethane (2.33 mmol, 4.0 equiv), 20 mL
of dry 1,4-dioxane, 10 mL of dry butanone, and 20 mL of dry DMF.
The product was purified by column chromatography (KG60,
dichloromethane/isohexanes solvent mixture (1/1)), washed with
isohexanes, and dried in vacuo to yield 92 mg of a yellow powder
3
3JHH = 7.6 Hz, 1 H, CHarom); 7.75 (d, JHH = 7.8 Hz, 1 H, CHarom);
3
3
7.67 (d, JHH = 8.2 Hz, 1 H, CHarom); 7.60 (d, JHH = 7.8 Hz, 1 H,
CHarom); 7.40 (t, 3JHH = 7.7 Hz, 1 H, CHarom); 7.30 (t, 3JHH = 7.5 Hz, 1
H, CHarom); 6.89 (s, 2 H, CHarom); 6.84 (s, 2 H, CHarom); 5.74 (s, 1 H,
(CO)CH(CO)); 4.01 (s, 3 H, CH3); 2.37 (s, 6 H, CH3); 2.32 (s, 9 H,
3 CH3); 2.29 (s, 3 H, CH3) ppm. 13C NMR (150.93 MHz, CDCl3): δ
185.3 (CO); 185.7 (CO); 156.1 (Carom); 154.05 (NCN); 142.6
(Carom); 142.3 (NCHN); 139.3 (Carom); 138.9 (Carom); 137.9 (Carom);
137.6 (Carom); 134.2 (Carom); 133.6 (Carom); 128.7 (Carom); 128.3
F
DOI: 10.1021/acs.organomet.5b00136
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(21%). Decomposition occurred above 300 °C. 1H NMR (600.16
MHz, CDCl3): δ 7.92 (s, 1 H, CHarom); 7.90 (s, 1 H, NCHN); 7.89 (d,
3JHH = 8.8 Hz, 1 H, CHarom); 7.87 (s, 1 H, CHarom); 7.49 (d, 3JHH = 8.2
Notes
The authors declare no competing financial interest.
3
Hz, 1 H, CHarom); 7.38 (t, 1 H, JHH = 7.7 Hz, 1 H, CHarom); 7.28 (t,
3JHH = 7.6 Hz, 1 H, CHarom); 6.89 (s, 2 H, CHarom); 6.85 (s, 2 H,
CHarom); 5.75 (s, 1 H, (CO)CH(CO)); 3.98 (s, 3 H, CH3); 2.37 (s, 6
H, CH3); 2.33 (s, 9 H, CH3); 2.30 (s, 3 H, CH3) ppm. 13C NMR
(150.93 MHz, CDCl3): δ 185.3 (CO); 184.9 (CO); 156.0 (CO); 154.2
(Carom); 152.4 (NCN); 141.6 (Carom); 140.9 (Carom); 139.4 (Carom);
138.8 (Carom); 137.9 (Carom); 137.6 (Carom); 134.1 (Carom); 133.7
(Carom); 128.3 (CHarom); 128.1 (CHarom); 126.0 (CHarom); 125.2
(Carom); 122.4 (CHarom); 119.8 (CHarom); 114.4 (CHarom); 111.6
(CHarom); 107.3 ((CO)CH(CO)); 103.9 (CHarom); 32.9 (NCH3);
21.1 (CH3); 21.1 (CH3); 19.9 (CH3); 19.6 (CH3) ppm. Signals for
one CH and 1 Carom were not observed in the 13C NMR spectrum.
195Pt NMR (128.56 MHz, CDCl3): δ −3363 ppm. Anal. Calcd for
C36H33N3O3Pt: C, 57.59; H, 4.43; N, 5.60. Found: C, 57.55; H, 4.32;
N, 5.47.
ACKNOWLEDGMENTS
■
We are grateful to the BMBF for support this project (FKZ:
13N10477) and the ZIH for computation time on their high-
performance computing facility. We also thank Dr. Benjamin
Breiten (BASF SE) and Dr. Christian Lennartz (BASF SE) for
helpful discussions and suggestions.
REFERENCES
■
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.5b00136.
■
S
Refinement details and X-ray crystallographic data for 8
and 11, emission spectra and data of the neat films of 7−
9, 11, and 12 at room temperature, 1H NMR, 13C NMR,
and 195Pt NMR spectra of 7−12 as well as several
different 2D spectra of 7-9, 11, and 12, full ref 46,
Cartesian coordinates and energies for all optimized
structures, and spatial plots of selected Kohn−Sham
orbitals of the optimized ground states of 7−12 (PDF)
X-ray crystallographic data for 8 and 11 (CIF)
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AUTHOR INFORMATION
Corresponding Author
*T.S.: thomas.strassner@chemie.tu-dresden.de; fax, 49 351
46339679; tel, 49 351 46338571.
■
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