Photoluminescence of a New Material: Cyclometalated C^C? Thiazole-2-ylidene Platinum(II) Complexes

Article abstract of DOI:10.1021/acs.organomet.5b00991

A new class of platinum(II) compounds, the 4,5-dimethyl-3-aryl-thiazole-2-ylidene platinum(II) acetylacetonato complexes, are described. Their efficient phosphorescent emission at room temperature makes them suitable for potential applications in organic light-emitting diodes. A new synthetic pathway that allows the preparation of a broad range of different N-arylthiazole-2-thiones and their subsequent conversion into the corresponding N-arylthiazolium perchlorate and hexafluorophosphate salts has been developed. Not only electron-rich (4-OMe, 4-Me, 3-Me) N-arylthiazoles but also electron-deficient ligands with a cyano or an ester group could be synthesized. From commercially available anilines N-arylthiazolium perchlorate and hexafluorophosphate salts were synthesized via ring-closure of in situ generated N-aryldithiocarbamate salts followed by a sulfur-oxidation/-substitution protocol to the air-stable carbene precursors. All reactions were performed in multigram scale in good yields. The synthesis of the corresponding platinum(II) complexes involves generating the corresponding N-arylthiazole-silver(I)-carbene complexes, transmetalation to platinum, cyclometalation, and reaction with acetylacetonate (acac). Solid-state structures of two N-arylthiazole-2-thiones, one N-arylthiazolium salt, and three N-arylthiazole-2-ylidene-platinum(II) complexes complement the analytic characterization including ¹⁹⁵Pt NMR. The unsubstituted complex 4,5-dimethyl-3-phenylthiazole-2-ylidene-platinum(II)-acac was additionally characterized by 2D-NMR techniques (COSY, HSQC, HMBC, NOESY). Photoluminescence measurements were performed in amorphous poly(methyl methacrylate) films and revealed bluish-green emission maxima (～500 nm) independent of the electronic structure of the thiazoles, whereas the variation of the substitution pattern at the cyclometalating aryl system led to excellent quantum efficiencies and decay lifetimes of 8.1-21.4 μs.

Full text of DOI:10.1021/acs.organomet.5b00991

Article
pubs.acs.org/Organometallics
Photoluminescence of a New Material: Cyclometalated C∧C*
Thiazole-2-ylidene Platinum(II) Complexes
Hendrik Leopold,† Alexander Tronnier,† 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: A new class of platinum(II) compounds, the 4,5-
dimethyl-3-aryl-thiazole-2-ylidene platinum(II) acetylacetonato
complexes, are described. Their efficient phosphorescent
emission at room temperature makes them suitable for potential
applications in organic light-emitting diodes. A new synthetic
pathway that allows the preparation of a broad range of different
N-arylthiazole-2-thiones and their subsequent conversion into
the corresponding N-arylthiazolium perchlorate and hexafluor-
ophosphate salts has been developed. Not only electron-rich (4-
OMe, 4-Me, 3-Me) N-arylthiazoles but also electron-deficient
ligands with a cyano or an ester group could be synthesized.
From commercially available anilines N-arylthiazolium perchlo-
rate and hexafluorophosphate salts were synthesized via ring-
closure of in situ generated N-aryldithiocarbamate salts followed by a sulfur-oxidation/-substitution protocol to the air-stable
carbene precursors. All reactions were performed in multigram scale in good yields. The synthesis of the corresponding
platinum(II) complexes involves generating the corresponding N-arylthiazole-silver(I)-carbene complexes, transmetalation to
platinum, cyclometalation, and reaction with acetylacetonate (acac). Solid-state structures of two N-arylthiazole-2-thiones, one N-
arylthiazolium salt, and three N-arylthiazole-2-ylidene-platinum(II) complexes complement the analytic characterization
including 195Pt NMR. The unsubstituted complex 4,5-dimethyl-3-phenylthiazole-2-ylidene-platinum(II)-acac was additionally
characterized by 2D-NMR techniques (COSY, HSQC, HMBC, NOESY). Photoluminescence measurements were performed in
amorphous poly(methyl methacrylate) films and revealed bluish-green emission maxima (∼500 nm) independent of the
electronic structure of the thiazoles, whereas the variation of the substitution pattern at the cyclometalating aryl system led to
excellent quantum efficiencies and decay lifetimes of 8.1−21.4 μs.
Sulfur-containing heterocycles and foremost their metal
complexes are currently also of great interest because of their
photophysical properties.10 Compared to typical reoccurring
motifs such as pyridine,11 triazole,12 and pyrazole structures,13
only a small percentage of sulfur-containing heterocycles are
found in emitter molecules.14 The most commonly described
structures contain C∧N-coordinated 2-aryl-1,3-thiazoles
(Scheme 1, III) at metals such as iridium15 or platinum16
and were shown to be interesting phosphorescent materials. To
date phosphorescent complexes, used in organic light-emitting
diodes (OLEDs), frequently rely on N-heterocyclic carbenes
(NHCs)17 derived from arylimidazole18 and aryltriazole19
structures to achieve defined emission wavelengths, high
quantum yields, and short decay lifetimes. We could only
find one report on the synthesis of cyclometalated ruthenium
NHC complexes based on the N-aryl-1,3-thiazole-2-ylidene
motif (Scheme 1, general motif IV) but without describing the
photophysical properties.20
INTRODUCTION
■
Sulfur-containing heterocycles have been an interesting and
challenging motif in organic synthesis for more than a century.1
From marine and terrestrial organisms, from simple industrial
products to essential structures and building blocks in the
human immune system, many different compounds have been
isolated and thoroughly investigated.2 Historically thiazole
structures were early found to show interesting properties and
have been studied up until today.3 Structure−activity relation-
ships of thiazole derivatives have been extensively investigated
to explain their biological effects.4 One is attributed to in situ
generated carbene structures (Scheme 1, general structure I)
followed by subsequent C2 substrate binding.5 The most
prominent example, the coenzyme thiamine (Scheme 1, II),
itself represents a thiazole-2-ylidene precursor. Such in situ
generated carbene structures6 and respectively their ruthenium
metal complexes7 have been investigated in detail for their
catalytic activities. Additionally, structurally diverse mesoionic
1,3-thiazole metal complexes were presented by Bertrand8 and
Shi.9
Received: December 4, 2015
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1. Overview of 1,3-Thiazole Compounds I−V
Scheme 2. Postulated Mechanism for the Formation of N-Aryl-thiazolium Salts (MX = NaClO4 or KPF6) with Highlighted
Isolated Compounds
Herein we report the synthesis and the photophysical
properties of a new class of C∧C* cyclometalated platinum(II)
N-arylthiazole-2-ylidene complexes with acetylacetonate ligands
(Scheme 1, V). We developed and optimized a new synthetic
route that allowed us to prepare structurally and electronically
diverse N-arylthiazolium perchlorate and hexafluorophosphate
salts starting from commercial anilines. The different electronic
structure of the N-arylthiazole (compared to typical imidazole
and triazole moieties) allowed us to develop a new type of
efficient blue to green room-temperature emitter molecules. We
studied the effect of electronically different substituents at the
cyclometalating aryl ring on the photoluminescence properties.
atom and two methyl groups in the 4- and 5-position of the
thiazole heterocycle by using 3-chloro-2-butanone (see Scheme
3). But unfortunately we found that the reported route does
Scheme 3. Synthesis of N-Arylthiazole-2-thiones 8−14 and
a
N-Arylthiazole-2-ium Salts 15−24
RESULTS AND DISCUSSION
■
Synthesis. For the synthesis of the general motif of the N-
arylthiazolium salts as carbene precursors there is recent
literature precedent using different approaches.7b,21 In partic-
ular the groups of Bach22 and Glorius23 used a two-step
reaction sequence starting from commercially available anilines.
The first step involves the reaction of different anilines with
carbon disulfide in a basic medium and leads to the formation
of the corresponding dithiocarbamate salts by a nucleophilic
attack on the CS2 carbon atom. The ring-closure is then
achieved by adding an α-haloketone compound. Substitution of
the chlorine atom by the nucleophilic sulfur atom is followed by
another nucleophilic attack of the nitrogen atom onto the
carbonyl function.24 Treatment of the crude N-arylhydroxy-
thiazolidine with hydrochloric acid finally yields the desired N-
arylthiazole-2-thione structures (see Scheme 2 for a possible
mechanism). Some N-arylthiazole structures with (sterically
demanding) alkyl substituents25 have been reported in the
literature, but only a few examples of electronic variations of the
phenyl ring can be found.26
a
(i) NaOH, DMSO, then CS2, 0 °C to rt, then 3-chloro-2-butanone, 0
°C to rt, aqueous workup; (ii) HCl, EtOH, reflux; (iii) 3 equiv of
H2O2, AcOH, rt; (iv) NaClO4 or KPF6, MeOH/H2O, rt.
not allow the synthesis of new compounds with electron-
donating or -withdrawing substituents. We therefore needed to
change the procedure for the N-arylthiazole-2-thione synthesis.
By using freshly ground sodium hydroxide, avoiding an aqueous
solution, we were able to transform even electron-deficient
anilines 2, 4, and 6 (Br, CN, CO2Me) as well as electron-rich
anilines 3, 5, and 7 (OMe, Me) into the desired thiazole
structures 8−14 (see Scheme 3). After the reaction all N-
arylthiazole-2-thiones 8−14 crystallized from the acidic
solution. Filtration, washing with alcohol, and drying gave the
Following the procedure reported by Bach22 and Glorius23
we were able to synthesize compound 8, previously reported by
different groups,27 with a phenyl ring attached to the nitrogen
B
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 4. Synthesized Platinum Complexes 25−31
pure N-arylthiazole-2-thiones 8−14 in good yields from 30% to
68% even on a larger scale of 25 to 50 mmol.
Scheme 5. Synthesis of the Cyclometalated Complexes 25−
a
31
The following generation of the N-arylthiazolium salts has
been described by different groups21−23 and involves an
oxidation/substitution protocol in an acidic medium. Slow
addition of H2O2 to an acetic acid solution of the N-
arylthiazole-2-thiones 8−14 reliably removed the thione sulfur
atom. As mentioned in the literature, this step includes the
stepwise formation of a sulfonic acid derivative by oxidation of
the thione sulfur atom.28 The hydrogen atom at C2 is then
introduced by a substitution/desulfonation process using a
proton from the acidic solution as electrophile (see Scheme
2).29 After evaporation of the solvent a salt metathesis yields
the desired products. Either sodium perchlorate or potassium
hexafluorophosphate was used to give the N-arylthiazolium
perchlorate (ClO4) or hexafluorophosphate (PF6) salts 15−24
(see Scheme 3). After a washing and extraction procedure (see
general procedure B in the Experimental Data section) all N-
arylthiazolium salts were isolated by slow precipitation upon
addition of diethyl ether to a concentrated dichloromethane
solution. Only in the case of the perchlorate salt 23 was a
further purification step using column chromatography
necessary. Overall the hexafluorophosphate salts tend to be
less hygroscopic compared to their perchlorate counterparts.
Therefore, the hexafluorophosphate salts were preferably used
for the complex synthesis, which is in need of dry reaction
conditions. Moreover the advantage of using the N-
arylthiazolium hexafluorophosphate salts over the perchlorate
compounds is that the formation of potentially dangerous silver
perchlorate in the drying process of the platinum(II) complex
synthesis (see Experimental Data section, general procedures C
and D) can be avoided. All N-arylthiazolium salts are obtained
in yields from 10% to 72% on a scale of 5 to 10 mmol.
a
(i) 0.55 equiv of Ag2O, rt to 50 °C, A: 1,4-dioxane (B: DMF) ; (ii)
Pt(COD)Cl2, rt to 115 °C, A: 1,4-dioxane/butanone (B: DMF); (iii)
4 equiv of Hacac, DMF, rt to 100 °C, A: 4 equiv of KOtBu (B: 4 equiv
of K2CO3).
Washing the bright yellow compounds with diethyl ether and
isohexanes yielded the pure complexes 25−31. Over the course
of this study we also focused on improving the yields and the
general experimental procedure of the complex synthesis. We
found DMF to be a superior solvent and lowered the basicity in
the final step by employing K2CO3 as the base (Scheme 5, B).
With this new protocol we were able to improve the yields of
complexes 25−28 by more than 50% (e.g., for complex 26 we
observed a 3-fold increase in comparison to the conventional
synthesis). Complexes 29−31 were subsequently prepared
using the new procedure. Noteworthy, even complex 31,
bearing an ester group, could be isolated analytically pure from
the basic reaction conditions showing no signs of an ester
hydrolysis. In conclusion seven new air-stable platinum(II)
complexes with an acetylacetonate ligand19a,31 based upon N-
arylthiazolium salts as precursors were prepared in good yields
of 24% up to 54% using the optimized one-pot procedure.
Characterization. All N-arylthiazole-2-thiones, N-arylthia-
zolium salts, and N-arylthiazole-2-ylidene platinum(II) com-
All complexes shown in Scheme 4 were prepared using an
established one-pot synthesis developed in our group.30 This
procedure involves the deprotonation of the carbene precursor
(here: N-arylthiazolium salts) in 1,4-dioxane using silver oxide
(Ag2O), transmetalation to dichloro(1,5-cyclooctadiene)-
platinum(II) (Pt(COD)Cl2), and cyclometalation by using a
temperature gradient in a dioxane/butanone mixture. Afterward
the acetylacetonate ligand is added under basic conditions in
dimethylformamide (DMF) using KOtBu as the base (see
Scheme 5, A). All complexes could be isolated by flash
chromatography using dichloromethane as the solvent.
1
plexes were investigated by standard techniques involving H
and 13C NMR, as well as gas chromatography mass
spectrometry (GCMS) for 8−14, electron spray ionization
mass spectrometry (ESI-MS) for 15−24, and 195Pt NMR for all
complexes 25−31. For complex 25 additional 2D-NMR spectra
C
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Figure 1. ORTEP representations of N-arylthiazole-2-thiones 8 and 9 and N-arylthiazolium salt 18. Thermal ellipsoids are drawn at the 50%
probability level.
Figure 2. ORTEP representations of thiazole-2-ylidene platinum(II) complexes 25−27. Thermal ellipsoids are drawn at the 50% probability level.
were recorded (COSY, HSQC, HMBC, and NOESY; see
Supporting Information).
25−31 show chemical shifts between −3346.21 and −3311.01
ppm in the 195Pt NMR. These values are similar to those
previously reported for imidazole- and triazole-based C∧C*
cyclometalated complexes with O∧O ligands.32
Depending on the substitution pattern, the melting points of
these novel platinum(II) complexes are quite different. Values
between 264 and 265 °C for the methoxy-substituted complex
27 and 277−278 °C in case of the bromo-substituted complex
26 can be observed. Complexes 28 and 30 show decomposition
at higher temperatures (>300 °C).
Solid-State Structure Determination. Single crystals of
8, 9, 18, 26, and 27 suitable for X-ray diffraction were obtained
by slow evaporation of a saturated dichloromethane solution
(Figures 1 and 2). Despite being bright yellow powders,
complexes 26 and 27 crystallized as dark green crystals after
evaporation. In the case of complex 25, a concentrated
dichloromethane solution was slowly infused with diethyl
ether to yield bright yellow crystals. Details of the solid-state
structure determination are given in the Supporting Informa-
tion (Tables S1 and S2).
Both N-arylthiazole-2-thiones 8 and 9 as shown in Table 1
reveal similar S1−C1 bond distances of 1.718(6) Å for the
unsubstituted thione 8 and of 1.726(10) Å for the bromo-
substituted compound 9. In addition the C1−N1 bond
distances (1.357(7) Å for 8 and 1.363(12) Å in the case of
compound 9) and S(1)−C(1)−N(1) angles (108.5(4)° for
compound 8 and 107.9(6)° for structure 9) show only minor
structural differences for the thiazole moiety. On the contrary
compounds 8 (−74.1(7)°) and 9 (−79.3(12)°) reveal different
C7−C6−N1−C1 torsions of the phenyl ring. Those values
differ significantly (by more than 10 degrees) from the results
of the DFT calculations, which show a nearly perpendicular
The 1H chemical shifts for the proton at the C2 carbon atom
of the N-arylthiazolium salts 15−24 were detected at 10.20−
10.29 ppm. For those salts the resonance of the C2 carbon
atom in the 13C NMR spectra was found at chemical shifts
between 157.04 and 157.86 ppm. The hexafluorophosphate
salts show melting points between 86 and 166 °C. In
comparison the perchlorate salts 15, 17, and 23 possess even
lower melting points compared to the corresponding
hexafluorophosphate salts. In addition to the cationic N-
arylthiazolium fragment detected by ESI-MS, all N-aryl-
thiazolium salts show higher m/z values that can be matched
to the formation of charged pairs consisting of two positive N-
arylthiazolium fragments and one counterion.
All complexes are bright yellow compounds and tend to
decompose in the NMR solvent CDCl3. As other typical NMR
solvents (MeOD, d3-MeCN, d6-benzene, d6-DMSO) could not
sufficiently dissolve complexes 25−31, all compounds were still
measured in CDCl3 but recorded as fast as possible to avoid
decomposition before or during the acquisition of the spectra.
In addition to the 4-methyl-substituted complex 29, the
regioisomer 31 with the methyl group in the 5-position was
synthesized to investigate the impact of the substitution pattern
on the photoluminescence properties. In principle two different
regioisomers regarding complex 31 could be formed (see DFT
section), but only complex 31, with the methyl group in the 5-
position, was isolated according to the NMR data (see
Experimental Data section).
We additionally recorded 195Pt NMR spectra of all seven N-
arylthiazol-2-ylidene platinum(II) complexes and compared the
resonances with values reported in the literature. Complexes
D
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
interaction of the phenyl ring with a thiazole ring from the
adjacent molecule (3.94 Å). Complex 26 shows a similar
formation of molecular pairs and crystallizes in a zigzag pattern
with an angle of about 53.1° between two molecular pairs.
Pt···Pt distances of about 7.03 Å are revealed as well as π−π
interactions between two N-aryl-thiazol-2-ylidene moieties of
3.68 Å. For complex 27 no pairs are found but a zigzag layer of
molecules with weak interactions between phenyl rings and
thiazole moieties (4.53−5.02 Å) as well as interactions between
the thiazole ring and the acetylacetonate ligand within 3.76 Å.
All Pt···Pt distances of the three complexes exceed the sum of
van der Waals radii for the platinum atom, indicating no
interaction between two platinum metal atoms (see Supporting
Information, Figures S4−S9).
In conclusion the N-arylthiazol-2-ylidene platinum(II)
complexes show similar bond distances and angles regarding
the central metal atom but provide a sterically less demanding
environment at the heterocyclic ring compared to typical
imidazole- and triazole-platinum(II) complexes with O∧O
ligands known from the literature.18b,19a,31−33 This is a very
promising result for the design of new emitter molecules.
Photoluminescence Properties. To investigate the
photophysical behavior for this new class of complexes, the
absorption and emission spectra at room temperature in doped
poly(methyl acrylate) (PMMA) (2 wt % complex) were
measured (see Supporting Information, Figures S12 and S13,
for absorption and emission data for 100% emitter films). For
all complexes a strong absorption between 250 and 280 nm is
observed, and only minor absorptions appear in the region
between 300 to 350 nm. Additionally local maxima in the low-
energy region of 360 to 370 nm can be observed for all
complexes (see Figure 3).
Table 1. Selected Bond Lengths (Å), Angles (deg), and
Dihedral Angles (deg) of the N-Arylthiazole-2-thiones 8 and
9 and the N-Arylthiazolium Salt 18
8
9
18
S1−C1
C1−N1
N1−C6
S1−C1−S2
S1−C1−N1
N1−C1−S2
C7−C6−N1−C1
1.718(6)
1.357(7)
1.434(7)
124.2(4)
108.5(4)
127.3(4)
−74.1(7)
1.726(10)
1.363(12)
1.458(12)
124.4(6)
107.9(6)
127.7(7)
−79.3(12)
1.657(8)
1.320(9)
1.446(9)
a
(124.0)
112.2(5)
−95.6(7)
178.3(4)
a
In the case of compound 18 this refers to S1−C1−H1.
orientation of the phenyl ring to the thiazole moiety (see
Supporting Information, Tables S5 and S6).
In comparison to the N-arylthiazole-2-thione structures 8
and 9 the N-arylthiazolium salt 18 shows shorter S1−C1
(1.657(8) Å) and C1−N1 (1.320(9) Å) bonds and a longer
C1−N1 (1.446(9) Å) bond. Additionally the S1−C1−N1 angle
(112.2(5)°) widens, whereas the N1−C1−S2 angle contracts
(95.6(7)°). These structural changes in bond distances and
angles further involve an almost perpendicular orientation
(95.6(7)°) of the 4-bromophenyl ring to the N,S-heterocycle
(for a comparison with DFT calculations see the Supporting
Information, Table S7). Further investigations of the solid-state
structure showed that no interactions of the ring structures
(carbocycle or thiazole) with neighboring N-arylthiazolium
molecules can be found due to the hexafluorophosphate anion,
which is positioned in between the N-arylthiazolium structures
(see Supporting Information, Figure S3).
Table 2. Selected Bond Lengths (Å), Angles (deg), and
Dihedral Angles (deg) of Complexes 25−27
25
26
27
C1−Pt
C7−Pt
Pt−O1
Pt−O2
1.907(11)
1.957(13)
2.076(8)
2.041(8)
79.9(5)
1.907(5)
1.967(4)
2.082(3)
2.052(3)
79.4(2)
90.61(13)
−2.7(5)
−1.2(4)
7.028
1.905(11)
2.002(11)
2.090(8)
2.044(7)
79.9(5)
91.4(3)
3.6(12)
6.8(9)
C1−Pt−C7
O1−Pt−O2
C1−N1−C6−C7
O2−Pt−O1−C13
90.7(3)
1.5(14)
−3.7(10)
5.338
a
Pt···Pt
7.002
a
Shortest intermolecular Pt−Pt distances.
All three complexes crystallize in a monoclinic crystal system
and reveal a square planar coordination of the platinum(II)
atom but with deviations from the ideal angles. While the O1−
Pt−O2 angles are the closest to 90°, the C1−Pt−C7 angles
(79.4(2)−79.9(5)°) show deviations of about 10 degrees as
also observed for the imidazole- and triazol-based C∧C*
platinum(II) complexes.19b,32a,33 The C1−Pt bond
(1.905(11)−1.907(5) Å) is the shortest of all platinum−ligand
bonds. The oxygen atom bond lengths show only minor
differences (2.041(8)−2.090(8) Å), while the C7−Pt bonds are
slightly shorter (1.957(13)−2.002)11) Å). Complex 25 forms
molecular pairs (Pt···Pt distances 5.34 Å) in the solid state that
are oriented at an angle of 49.19° toward the next molecular
pair (both metallacycles were used for the calculation of the
planes). Within two molecules π−π interactions between the
N-aryl-thiazol-2-ylidene moieties are found, revealing an
Figure 3. Absorption spectra of complexes 25−31 at room
temperature (2 wt % in PMMA).
All new N-arylthiazole-2-ylidene platinum(II) complexes
show interesting photoluminescence data (see Table 3), as
they emit at room temperature and show high quantum yields,
decay lifetimes of 8.1−21.4 μs, and remarkably stable emission
maxima between 508 and 526 nm (see Figure 4). Interestingly
all complexes emit in a very narrow range and retain their blue-
green maximum emission wavelengths, almost independent
from electron-donating or electron-withdrawing groups at the
cyclometalating aryl ring, as only the shape of the emission
spectra changed. Broad unstructured bands can be observed for
E
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
and methyl substitution (complexes 27 and 29) decrease the
overall quantum yield. In contrast negative mesomeric and
inductive effects present in complexes 28 and 30 (CN and
CO2Me substituent) improve the quantum yields and lower the
decay lifetimes. All comparisons are always related to the
unsubstituted complex 25. The bromo-substituted compound
26 has a strong positive mesomeric effect and a small negative
inductive effect showing a higher quantum yield than complex
25 and shorter decay lifetimes.
Comparing complexes 29 and 31, the decay lifetime of
complex 31 could be lowered by 4 μs, but quantum yields and
emission wavelengths are almost identical (see Supporting
Information, Figures S10 and S11 for a direct comparison of
absorption and emission spectra). In conclusion changing the
position of the methyl substituent showed no significant
improvement; hence no further variation was investigated.
Complexes 25−28 show remarkably better photolumines-
cence properties compared to their imidazole analogues.30 Also
complexes 25 and 28, when compared to their triazole-based
equivalents,19b show enhanced quantum yields while maintain-
ing good decay lifetimes. These data are very promising for
developing new highly efficient emitters and their implementa-
tion in modern day phosphorescent OLEDs (PhOLEDs).
Quantum Chemical Calculations. All geometry optimi-
zations including ground-state and triplet-state geometries were
performed using DFT methods. As stated in the Character-
ization section complex 31 could possibly form two different
regioisomers, but only the cyclometalated structure with the
methyl group in the 5-position was isolated (see Figure 5).
Table 3. Photoluminescence Data (2 wt % in PMMA, rt) of
the Cyclometalated Complexes 25−31
λ
λ
τ
kr (103 knr (103
f g
exc a
b
em c
d
0 e
(nm)
CIE x;y
(nm)
ϕ
(μs)
s−1
)
s−1
)
25
26
27
28
29
30
31
370
360
360
370
360
370
360
0.28;0.52
0.32;0.50
0.34;0.55
0.39;0.49
0.30;0.54
0.31;0.55
0.31;0.56
510
508
526
515
516
520
521
0.61
0.67
0.33
0.72
0.51
0.79
0.51
11.64
9.30
85.7
107.0
46.2
2776.8
2065.8
4790.5
2192.4
3273.2
1703.1
2454.9
21.39
10.93
13.09
8.11
92.0
76.3
97.4
9.83
101.8
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 τ0 = τv/ϕ. kr = ϕ/τv. knr = (1 − ϕ)/τv.
f
g
Figure 4. Emission spectra of complexes 25−31 at room temperature
(2 wt % in PMMA).
compounds 25−27, 29, and 31, whereas complexes 28 and 30
show a spectrum with a vibronic coupling (progression
distances of about 1120−1270 cm−1 for complex 28 and
about 1070−1180 cm−1 for complex 30). In addition to the
(global) maximum at 515 nm a second (local) maximum at
about 640 nm can be observed for complex 28. These
observations support a different emission process for complexes
with electron-withdrawing substituents at the aryl system (28,
30) compared to the (mainly) electron-donating substituents
present in complexes 25−27, 29, and 31.
While keeping stable blue-green emissions the substituents at
the cyclometalating aryl ring furthermore enhance the quantum
yields and the decay lifetimes. The unsubstituted complex 25
reveals quantum yields as high as 61%, a much higher intrinsic
value when compared to the analogous triazole or imidazole
complexes.19b,30 Overall quantum yields from 33% up to 79%
and decay lifetimes ranging from 8.1 to 21.4 μs were achieved
by a variation of the substitution pattern at the cyclometalating
aryl ring. We were pleased to find that the ester-substituted
complex 30 not only showed the highest quantum yields and
lowest τ0 value but also retained high quantum yields of about
68% in the 100% film. All other complexes show lower
quantum yields in the pure emitter film and a red-shift of the
emission wavelength maxima (see Supporting Information
Table S3).
Figure 5. DFT (B3LYP/6-31G(d))-calculated geometries of possible
isomers of complex 31.
Quantum chemical calculations support the formation of the 5-
Me isomer, showing an energy difference of about 4 kcal/mol
in favor of the sterically less hindered Pt environment (see
Supporting Information, Table S4).
The calculated geometries and the solid-state structures are
in very good agreement. Calculations on the triple-ζ level using
B3LYP/6-311++G(d,p) show only minor geometrical changes
for bond distances (up to 1%) and angles (up to 2%) compared
to the structures obtained with B3LYP/6-31G(d) or BP86/6-
31G(d). All three methods place the platinum atom in a
perfectly planar environment, whereas the N1−C1−Pt−O1
dihedral angle in the solid-state structures shows a slight torsion
of up to 2.8 degrees (see Supporting Information, Tables S8−
S11, for a direct comparison).
The triplet-state geometries calculated by B3LYP/6-31G(d)
show distortions of the thiazole ring system in comparison to
the calculated singlet structures. Next to the distorted N1−C1−
Pt−O1 dihedral angles, which slightly twist the NHC−ligand
In summary concerning the 2 wt % PMMA films, positive
mesomeric or inductive effects originating from the methoxy
F
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
internally by using the resonances of the solvent (1H: 7.26 ppm, 13C:
(171.1−175.0°), elongated C1−N1 bonds with differences of
0.98−1.17 Å and shortened N1−C6 distances with deviations
of 0.65−0.82 Å are observed (see Supporting Information,
Table S10). There is almost no change in the Pt−C and Pt−O
bond distances, and no out-of-plane bending of the
acetylacetonate ligand can be observed (also in the case of
BP86). Spin densities based on B3LYP/6-31G(d) reveal a
strong influence of the N-arylthiazole ligand and just a small
contribution from the acetylacetonate (acac) system. This
indicates that the main emission process is controlled by the
thiazole-aryl moiety and therefore represents intraligand
charge-transfer (ILCT) or metal-to-ligand charge-transfer
(MLCT) character (see Supporting Information, Figure S15).
Using a previously described method developed in our group
we could successfully predict the emission maxima by BP86/6-
31G(d) and B3LYP/6-31G(d) calculations.34 All complexes
and their emission wavelengths could be well described and
predicted.
1
77.0 ppm for CDCl3; H: 2.50 ppm, 13C: 39.43 ppm for DMSO-d6).
195Pt NMR spectra were referenced externally by using potassium
tetrachloroplatinate(II) in D2O (−1617.2 PtCl42−, −2654.1 PtCl2).
Shifts are given in ppm; coupling constants J in Hz. Mass spectra of
thiones 8−14 were recorded on an Agilent 6890N GC coupled with a
5973N MSD system using electron ionization (EI) as ionization
method. Electrospray ionization (ESI) mass spectra of the N-
arylthiazolium salts 15−24 were measured on a Bruker Esquire MS
with an ion trap detector. Elemental analyses were performed on a
Hekatech elemental analyzer by the microanalytical laboratory of our
institute. Uncorrected melting points have been determined using a
Wagner and Munz Poly Therm A system. The emitter films were
prepared by doctor blading a solution of emitter in a 10 wt % PMMA
solution in dichloromethane on a substrate with a 60 μm doctor blade.
X-ray Crystallography. Preliminary examination and data
collection were carried out on a NONIUS κ-CCD diffraction system
(FR590) equipped with an Oxford Cryosystem cooling system at the
window of a fine-focus sealed tube using graphite-monochromated Mo
Kα radiation (λ = 0.710 73 Å). The reflections were merged and
corrected for Lorentz, polarization, and decay effects. An absorption
correction was applied using SADABS.37 The structures were solved
by a combination of direct methods38 with the aid of difference
Fourier synthesis and were refined against all data using SHELXL-
97.39 Hydrogen atoms were assigned to ideal positions using the
SHELXL-97 riding model. All non-hydrogen atoms were refined with
anisotropic displacement parameters. Full-matrix least-squares refine-
CONCLUSION
■
The first seven C∧C* cyclometalated Pt(II) acetylacetonate
complexes with 1,3-thiazole-based NHC ligands could be
synthesized, and their photophysical properties were inves-
tigated. A series of N-arylthiazole-2-thiones with electron-
donating (OMe, Br, Me) as well as electron-withdrawing
groups (CN, CO2Me) could be synthesized. With overall yields
of up to 48% air-stable N-arylthiazolium perchlorate and
especially hexafluorophosphate salts were accessible in gram
scale. They allowed controlling the electronic effect on the
platinum atom and the overall absorption/emission process by
variation of the substitution at the cyclometalating aryl ring. All
complexes are efficiently emitting at room temperature with
high quantum yields. These newly synthesized N-arylthiazol-2-
ylidene platinum(II) complexes show remarkable stable
emissions of about 508−526 nm independent from the
substitution pattern. Quantum yields could be improved from
33% up to an excellent 79% with decay lifetimes between 8.1
and 21.4 μs in 2% PMMA films. The complex with methyl ester
substituent not only showed the highest quantum yields of 79%
but even retained excellent quantum yields of 68% in the
concentrated film. The solid-state structures of two N-
arylthiazol-2-thiones, one N-arylthiazolium hexafluorophos-
phate salt, and three N-arylthiazol-2-ylidene platinum(II)
complexes provided structural information. In addition all
solid-state structures are in good agreement compared to the
results of quantum chemical DFT calculations. These new
thiazole complexes are promising emitters for applications in
OLEDs.
2
ments were carried out by minimizing ∑w(Fo − Fc2)2 with the
SHELXL-97 weighting scheme. Details of the structure determinations
are given in the Supporting Information. Neutral-atom scattering
factors for all atoms and anomalous dispersion corrections for the non-
hydrogen atoms were taken from the International Tables for
Crystallography.40 All calculations were performed with the programs
COLLECT,41 DIRAX,42 EVALCCD,43 SIR92,38a SIR97,38b SA-
DABS,37 the SHELXL-97 package,39,44 and PLATON.45 Images of
the solid-state structures were generated with ORTEP-346 and
MERCURY.47
Computational Details. The Gaussian09 package48 was used to
perform all quantum chemical calculations employing the density
functional hybrid model B3LYP49 and gradient-corrected BP86.50
Both functionals were combined with a 6-31G(d) basis set51 further
using a double valence basis set for bromine.52 In addition B3LYP was
combined with a 6-311++G(d,p) triple-ζ basis set.53 In all calculations
platinum was described with a decontracted Hay−Wadt(n+1) ECP
and basis set.54 All given structures were verified as true minima by
vibrational frequency analysis and the absence of negative eigenvalues.
By applying thermochemical analysis approximate free energies could
be obtained. Thermal corrections to Gibbs free energy, as reported by
Gaussian09, were taken into account including zero-point effects,
thermal enthalpy corrections, and entropy. All presented energies,
unless otherwise stated, are free energies at standard conditions (T =
298 K, p = 1 atm) using unscaled frequencies. Frontier molecule
orbitals (FMOs) and spin densities were visualized by GaussView.55
Calculated geometries were visualized with CYLview.56
General Procedure A: N-Arylthiazole-2-thiones. According to
a modified literature procedure,22,23 0.4 mL/mmol of DMSO and 1
equiv of the corresponding aniline (1−7) were mixed, and 1 equiv of
freshly ground NaOH was added at room temperature in one portion.
The solution immediately darkened. After 15 min of stirring at room
temperature 1 equiv of CS2 was added at 0 °C. A further 60 min of
stirring at room temperature was followed by the slow addition of 1
equiv of 3-chloro-2-butanone at 0 °C. This led to another color change
and slight evolution of HCl. The solution was diluted with 200 mL of
distilled water after 60 min of stirring at room temperature and then
vigorously stirred for another 30 min. A crude solid precipitated in the
case of aniline 1 and 2, whereas anilines 3−7 yielded a viscous oil.
After 30 min of standing at 5 °C the water phase was decanted and the
remaining oil or solid dissolved in 125 mL of EtOH. The concluding
elimination was performed by refluxing the ethanolic solution with 1.5
mL of concentrated hydrochloric acid (37 wt %) for 1 h. The product
EXPERIMENTAL DATA
■
General Considerations. All complex syntheses were performed
under an argon atmosphere and with exclusion of light, using flame-
dried Schlenk tubes. Unless otherwise stated, all other syntheses were
run without using an inert atmosphere. Solvents of at least 99.0%
purity were used in this study. DMF and 1,4-dioxane were dried using
standard techniques and stored under an argon atmosphere over
molecular sieves (3 Å). Dichloro(1,5-cyclooctadiene)platinum(II)
(Pt(COD)Cl2)35 was prepared following a modified literature
procedure.30 Compound 636 was prepared according to the literature
procedure. Compounds 8,27 9,27c and 1227c have been synthesized
following a modified procedure described below. Chemicals were
obtained from common suppliers and used without further
purification. 1H, 13C, and 195Pt NMR spectra were recorded on Bruker
NMR spectrometers. 1H and 13C NMR spectra were referenced
G
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
crystallized after one night of standing at 5 °C. Filtration of the
remaining solid, washing once with 0.4 mL/mmol of EtOH, and
drying under high vacuum yielded pure 3-aryl-4,5-dimethylthiazole-2-
thiones.
for C12H10N2S2: C, 58.51; H, 4.09; N, 11.37; S, 26.03. Found: C,
58.31; H, 3.98; N, 11.41; S, 25.99.
3-(4-Methylphenyl)-4,5-dimethyl-1,3-thiazole-2(3H)-thione
(12). According to general procedure A 5.34 g (50 mmol) of aniline 5
and 2 g (50 mmol) of NaOH were added to 20 mL of DMSO
followed by 3.02 mL of CS2 (3.81 g, 1 equiv, 50 mmol) and 5.18 mL
of 3-chloro-2-butanone (5.49 g, 1 equiv, 50 mmol, 97 wt %). The next
steps involving removal of the water phase and acidic elimination were
conducted as described in general procedure A. The crystallized
product was filtered, washed with 20 mL of EtOH, and dried under
high vacuum to yield compound 12 as a pale brown solid (5.44 g,
46.2%). Mp: 123−124 °C. 1H NMR (300 MHz, DMSO-d6): δ 1.80 (s,
3H, CH3), 2.18 (s, 3H, CH3), 2.38 (s, 3H, CH3), 7.17 (d, J = 8.3 Hz,
2H, CHarom), 7.36 (d, J = 8.4 Hz, 2H, CHarom). 13C NMR (75 MHz,
DMSO-d6): δ 186.25 (CS), 138.73 (Ci), 135.68 (Ci), 135.46 (Ci),
130.03 (2C, CHarom), 127.95 (2C, CHarom.), 116.61 (Ci), 20.67 (CH3),
13.33 (CH3), 11.18 (CH3). GCMS (EI): m/z (fragment, %) 235 (M+,
100), 220 (M+ − Me, 10). Anal. Calcd for C12H13NS2: C, 61.24; H,
5.57; N, 5.95; S, 27.25. Found: C, 61.58; H, 5.66; N, 5.96; S, 27.12.
3-(4-Benzoic acid methyl ester)-4,5-dimethyl-1,3-thiazole-
2(3H)-thione (13). According to general procedure A 3.78 g (25
mmol) of aniline 6 and 1 g (25 mmol) of NaOH were added to 10 mL
of DMSO followed by 1.51 mL of CS2 (1.90 g, 1 equiv, 25 mmol) and
2.59 mL of 3-chloro-2-butanone (2.75 g, 1 equiv, 25 mmol, 97 wt %).
The next steps involving removal of the water phase and acidic
elimination were conducted as described in general procedure A but
using MeOH instead of EtOH. The crystallized product was filtered,
washed with 10 mL of MeOH, and dried under high vacuum to yield
compound 13 as a brown solid (2.16 g, 30.9%). Mp: 150−151 °C. 1H
NMR (300 MHz, DMSO-d6): δ 1.82 (s, 3H, CH3), 2.20 (s, 3H, CH3),
3.90 (s, 3H, CH3), 7.51 (d, J = 8.4 Hz, 2H, CHarom), 8.12 (d, J = 8.4
Hz, 2H, CHarom). 13C NMR (75 MHz, DMSO-d6): δ 186.24 (CS),
165.40 (Ci), 142.22 (Ci), 134.99 (Ci), 130.40 (2C, CHarom), 130.29
(Ci), 129.28 (2C, CHarom), 117.36 (Ci), 52.39 (CH3), 13.23 (CH3),
11.16 (CH3). GCMS (EI): m/z (fragment, %) 279 (M+, 100), 264
(M+ − Me, 5). Anal. Calcd for C13H13NO2S2: C, 55.89; H, 5.01; N,
5.01; S, 22.95. Found: C, 55.92; H, 4.67; N, 5.09; S, 22.77.
3-(3-Methylphenyl)-4,5-dimethyl-1,3-thiazole-2(3H)-thione
(14). According to general procedure A 5.36 g (50 mmol) of aniline 5
and 2 g (50 mmol) of NaOH were added to 20 mL of DMSO
followed by 3.02 mL of CS2 (3.81 g, 1 equiv, 50 mmol) and 5.18 mL
of 3-chloro-2-butanone (5.49 g, 1 equiv, 50 mmol, 97 wt %). The next
steps involving removal of the water phase and acidic elimination were
conducted as described in general procedure A. The crystallized
product was filtered, washed with 20 mL of EtOH, and dried under
high vacuum to yield compound 14 as a pale brown solid (5.61 g,
47.7%). Mp: 118−119 °C. 1H NMR (300 MHz, DMSO-d6): δ 1.81 (s,
3H, CH3), 2.18 (s, 3H, CH3), 2.37 (s, 3H, CH3), 7.00−7.14 (m, 2H,
CHarom), 7.32 (d, J = 7.6 Hz, 1H, CHarom), 7.45 (d, J = 7.8 Hz, 1H,
CHarom). 13C NMR (75 MHz, DMSO-d6): δ 186.14 (CS), 139.21 (Ci),
138.20 (Ci), 135.39 (Ci), 129.84 (CHarom.), 129.35 (CHarom), 128.52
(CHarom), 125.23 (CHarom), 116.76 (Ci), 20.67 (CH3), 13.32 (CH3),
11.18 (CH3). GCMS (EI): m/z (fragment, %) 235 (M+, 98), 220 (M+
− Me, 5). Anal. Calcd for C12H13NS2: C, 61.24; H, 5.57; N, 5.95; S,
27.25. Found: C, 61.10; H, 5.56; N, 5.86; S, 27.54.
4,5-Dimethyl-3-phenyl-1,3-thiazole-2(3H)-thione (8). Accord-
ing to general procedure A 4.66 g (4.56 mL, 50 mmol) of aniline 1 and
2 g (50 mmol) of NaOH were added to 20 mL of DMSO followed by
3.02 mL of CS2 (3.81 g, 1 equiv, 50 mmol) and 5.18 mL of 3-chloro-2-
butanone (5.49 g, 1 equiv, 50 mmol, 97 wt %). The next steps
involving removal of the water phase and acidic elimination were
conducted as described in general procedure A. The crystallized
product was filtered, washed with 20 mL of EtOH, and dried under
high vacuum to yield compound 8 as a pale brown solid (7.48 g,
1
67.6%). Mp: 87 °C. H NMR (300 MHz, DMSO-d6): δ 1.80 (s, 3H,
CH3), 2.19 (s, 3H, CH3), 7.30 (d, J = 6.8 Hz, 2H, CHarom), 7.41−7.69
(m, 3H, CHarom). 13C NMR (75 MHz, DMSO-d6): δ 186.23 (CS),
138.25 (Ci), 135.35 (Ci), 129.56 (2C, CHarom), 129.18 (CHarom),
128.28 (2C, CHarom), 116.80 (Ci), 13.32 (CH3), 11.18 (CH3). GCMS
(EI): m/z (fragment, %) 221 (M+, 100). Anal. Calcd for C11H11NS2:
C, 59.69; H, 5.01; N, 6.33; S, 28.97. Found: C, 59.49; H 4.98; N, 6.25;
S, 28.93.
3-(4-Bromophenyl)-4,5-dimethyl-1,3-thiazole-2(3H)-thione
(9). According to general procedure A 4.39 g (25 mmol) of aniline 2
and 1 g (25 mmol) of NaOH were added to 10 mL of DMSO
followed by 1.51 mL of CS2 (1.90 g, 1 equiv, 25 mmol) and 2.59 mL
of 3-chloro-2-butanone (2.75 g, 1 equiv, 25 mmol, 97 wt %). The next
steps involving removal of the water phase and acidic elimination were
conducted as described in general procedure A. The crystallized
product was filtered, washed with 10 mL of EtOH, and dried under
high vacuum to yield compound 9 as a brown solid (4.62 g, 61.6%).
1
Mp: 130 °C. H NMR (300 MHz, DMSO-d6): δ 1.83 (s, 3H, CH3),
2.19 (s, 3H, CH3), 7.31 (d, J = 8.7 Hz, 2H, CHarom), 7.77 (d, J = 8.7
Hz, 2H, CHarom). 13C NMR (75 MHz, DMSO-d6): δ 186.34 (CS),
137.47 (Ci), 135.18 (Ci), 132.61 (2C, CHarom), 130.67 (2C, CHarom),
122.49 (Ci), 116.99 (Ci), 13.30 (CH3), 11.17 (CH3). GCMS (EI): m/z
(fragment, %) 300 (M+, 100), 220 (M+ − Br, 31). Anal. Calcd for
C11H10BrNS2: C, 44.00; H, 3.36; N, 4.67; S, 21.36. Found: C, 44.02;
H, 3.35; N, 4.69; S, 21.15.
3-(4-Methoxyphenyl)-4,5-dimethyl-1,3-thiazole-2(3H)-thi-
one (10). According to general procedure A 6.22 g (50 mmol) of
aniline 3 and 2 g (50 mmol) of NaOH were added to 20 mL of
DMSO followed by 3.02 mL of CS2 (3.81 g, 1 equiv, 50 mmol) and
5.18 mL of 3-chloro-2-butanone (5.49 g, 1 equiv, 50 mmol, 97 wt %).
The next steps involving removal of the water phase and acidic
elimination were conducted as described in general procedure A. The
crystallized product was filtered, washed with 20 mL of EtOH, and
dried under high vacuum to yield compound 10 as a violet solid (6.06
g, 48.2%). Mp: 90−91 °C. 1H NMR (300 MHz, DMSO-d6): δ 1.81 (s,
3H, CH3), 2.18 (s, 3H, CH3), 3.82 (s, 3H, CH3), 7.08 (d, J = 9.0 Hz,
2H, CHarom), 7.22 (d, J = 9.0 Hz, 2H, CHarom). 13C NMR (125 MHz,
DMSO-d6): δ 186.48 (CS), 159.33 (Ci), 135.73 (Ci), 130.81 (Ci),
129.42 (2C, CHarom), 116.39 (Ci), 114.64 (2C, CHarom), 55.33 (CH3),
13.39 (CH3), 11.23 (CH3). GCMS (EI): m/z (fragment, %) 251 (M+,
100), 236 (M+ − Me, 33). Anal. Calcd for C12H13NOS2: C, 57.34; H,
5.21; N, 5.57; S, 25.51. Found: C, 57.45; H, 5.24; N, 5.62; S, 25.74.
3-(4-Cyanophenyl)-4,5-dimethyl-1,3-thiazole-2(3H)-thione
(11). According to general procedure A 5.91 g (50 mmol) of aniline 4
and 2 g (50 mmol) of NaOH were added to 20 mL of DMSO
followed by 3.02 mL of CS2 (3.81 g, 1 equiv, 50 mmol) and 5.18 mL
of 3-chloro-2-butanone (5.49 g, 1 equiv, 50 mmol, 97 wt %). The next
steps involving removal of the water phase and acidic elimination were
conducted as described in general procedure A. The crystallized
product was filtered, washed with 20 mL of EtOH, and dried under
high vacuum to yield compound 11 as an off-white solid (6.19 g,
50.3%). Mp: 211 °C. 1H NMR (300 MHz, DMSO-d6): δ 1.82 (s, 3H,
CH3), 2.20 (s, 3H, CH3), 7.61 (d, J = 8.4 Hz, 2H, CHarom), 8.07 (d, J =
8.3 Hz, 2H, CHarom). 13C NMR (125 MHz, DMSO-d6): δ 186.25
(CS), 142.09 (Ci), 134.85 (Ci), 133.69 (2C, CHarom), 129.91 (2C,
CHarom), 117.93 (Ci), 117.39 (Ci), 112.11 (Ci), 13.16 (CH3), 11.09
(CH3). GCMS (EI): m/z (fragment, %) 246 (M+, 100). Anal. Calcd
General Procedure B: N-Arylthiazolium Salts. According to a
modified literature procedure,22,23 a dispersion of the corresponding 3-
aryl-4,5-dimethylthiazole-2-thione (15−24) and 2.5 mL/mmol of
AcOH was slowly treated with 3 equiv of H2O2 (30 wt % in water;
Warning! Exothermic reaction!). The solid dissolved, and the clear
orange solution was stirred at room temperature for another 30 min.
The solvent was removed in vacuo, and the remaining oil dissolved in 2
mL/mmol MeOH. A mixture of 4 mL/mmol MeOH/water (1:1) and
2 equiv KPF6 or 2 equiv NaClO4-monohydrate were added. A salt
precipitated after the addition was completed, and the dispersion was
stirred at room temperature for 16 h. The solids were filtered off, and
the remaining solution was transferred to a separation funnel
containing 100 mL of distilled water. The resulting water phase was
extracted with 50 mL of dichloromethane first, followed by another
extraction with 100 mL of dichloromethane. The combined organic
H
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
−
phases were dried over Na2SO4, and the drying agent was filtered off.
After evaporation of the solvent the resulting oil was dissolved in 2 mL
of dichloromethane and the product was precipitated by slow addition
of diethyl ether. The solid was filtered and washed with ether before
drying under high vacuum.
(2[NHC]+ + PF6 ). Anal. Calcd for C11H11BrF6NPS: C, 31.90; H,
2.68; N, 3.38; S, 7.74. Found: C, 31.66; H, 2.48; N, 3.35; S, 7.88.
3-(4-Methoxyphenyl)-4,5-dimethyl-1,3-thiazolium Hexa-
fluorophosphate (19). According to general procedure B, 1.26 g
(5 mmol) of 3-aryl-4,5-dimethylthiazole-2-thione 10 in 13 mL of
AcOH was treated with 1.53 mL of H2O2 (15 mmol). Following
general procedure B the oil was dissolved in 10 mL of MeOH, and a
mixture of 20 mL MeOH/water (1:1) and 1.84 g of KPF6 (20 mmol, 2
equiv) was added. After extraction the precipitated solid was filtered
and washed with ether before drying under high vacuum. Compound
19 was obtained as a brown solid (889 mg, 48.7%). Mp: 157−159 °C.
1H NMR (300 MHz, DMSO-d6): δ 2.20 (s, 3H, CH3), 2.57 (s, 3H,
4,5-Dimethyl-3-phenyl-1,3-thiazolium Perchlorate (15). Ac-
cording to general procedure B 1.99 g (9 mmol) of 3-aryl-4,5-
dimethylthiazole-2-thione 8 in 23 mL of AcOH was treated with 2.75
mL of H2O2 (27 mmol). Following general procedure B the oil was
dissolved in 18 mL of MeOH, and a mixture of 36 mL MeOH/water
(1:1) and 2.53 g of NaClO4·H2O (18 mmol, 2 equiv) was added. After
extraction the precipitated solid was filtered and washed with ether
before drying under high vacuum. Compound 15 was obtained as a
brown solid (1.87 g, 71.7%). Mp: 104−106 °C. NMR (300 MHz,
DMSO-d6): δ 2.21 (s, 3H, CH3), 2.59 (s, 3H, CH3), 7.68−7.74 (m,
5H, CHarom), 10.25 (s, 1H, N(CH)S). 13C NMR (125 MHz, DMSO-
d6): δ 157.07 (N(CH)S), 142.05 (Ci), 137.01 (Ci), 132.69 (Ci), 131.27
(CHarom), 129.96 (2C, CHarom), 126.14 (2C, CHarom), 12.01(CH3),
11.94 (CH3). MS (ESI): m/z (fragment) 190.0 (M+), 479.0
CH3), 3.87 (s, 3H, CH3), 7.21 (d, J = 8.8 Hz, 2H, CHarom), 7.63 (d, J =
8.8 Hz, 2H, CHarom), 10.19 (s, 1H, N(CH)S). 13C NMR (75 MHz,
DMSO-d6): δ 160.88 (Ci-OCH3), 157.06 (N(CH)S), 142.28 (Ci),
132.36 (Ci), 129.70 (Ci), 127.49 (2C, CHarom), 114.88 (2C, CHarom),
55.71 (OCH3), 12.02 (CH3), 11.91(CH3). MS (ESI): m/z (%) 220.0
([NHC]+), 585.0 (2[NHC]+
+
PF6−). Anal. Calcd for
C12H14F6NOPS: C, 39.46; H, 3.86; N, 3.83; S, 8.78. Found: C,
39.28; H, 3.73; N, 3.56; S, 8.97.
−
(2[NHC]+ + ClO4 ). Anal. Calcd for C11H12ClNO4S: C, 45.60; H,
3-(4-Cyanophenyl)-4,5-dimethyl-1,3-thiazolium Hexafluoro-
phosphate (20). According to general procedure B, 1.23 g (5 mmol)
of 3-aryl-4,5-dimethylthiazole-2-thione 11 in 13 mL of AcOH was
treated with 1.53 mL of H2O2 (15 mmol). Following general
procedure B the oil was dissolved in 10 mL of MeOH, and a mixture
of 20 mL of MeOH/water (1:1) and 1.84 g of KPF6 (20 mmol, 2
equiv) was added. After extraction the precipitated solid was filtered
and washed with ether before drying under high vacuum. Compound
20 was obtained as a brown solid (174 mg, 9.6%). Mp: 125−132 °C.
1H NMR (300 MHz, DMSO-d6): δ 2.21 (s, 3H, CH3), 2.59 (s, 3H,
4.17; N, 4.83; S, 11.07. Found: C, 45.87; H, 4.08; N, 4.56; S, 11.30.
4,5-Dimethyl-3-phenyl-1,3-thiazolium Hexafluorophos-
phate (16). According to general procedure B 2.21 g (10 mmol) of
3-aryl-4,5-dimethylthiazole-2-thione 8 in 25 mL of AcOH was treated
with 3.06 mL of H2O2 (30 mmol). Following general procedure B the
oil was dissolved in 20 mL of MeOH and a mixture of 40 mL of
MeOH/water (1:1) and 3.68 g of KPF6 (20 mmol, 2 equiv) was
added. After extraction the precipitated solid was filtered and washed
with ether before drying under high vacuum. Compound 16 was
obtained as a brown solid (2.14 g, 63.9%). Mp: 115−120 °C. 1H NMR
(300 MHz, DMSO-d6): δ 2.21 (s, 3H, CH3), 2.57 (s, 3H, CH3), 7.66−
7.80 (m, 5H, CHarom) 10.26 (s, 1H, N(CH)S). 13C NMR (75 MHz,
DMSO-d6): δ 157.12 (N(CH)S), 142.03 (Ci), 136.98 (Ci), 132.85
(Ci), 131.25 (CHarom), 129.94 (2C, CHarom), 126.13 (2C, CHarom),
11.98 (CH3), 11.92 (CH3). MS (ESI): m/z (fragment) 190.0 (M+),
CH3), 7.95 (d, J = 8.2 Hz, 2H, CHarom), 8.24 (d, J = 8.3 Hz, 2H,
CHarom.), 10.29 (s, 1H, N(CH)S). 13C NMR (75 MHz, DMSO-d6): δ
157.77 (N(CH)S), 141.90 (Ci), 140.26 (Ci), 134.06 (2C, CHarom),
132.88 (Ci), 127.68 (2C, CHarom), 117.57 (CN), 114.10 (Carom-CN),
11.92 (CH3), 11.87 (CH3). MS (ESI): m/z (fragment) 215.0 (M+),
−
575.0 (2[NHC]+ + PF6 ). Anal. Calcd for C12H11F6N2PS: C, 40.01; H,
−
525.0 (2[NHC]+ + PF6 ). Anal. Calcd for C11H12F6NPS: C, 39.41; H,
3.08; N, 7.78; S, 8.90. Found: C, 40.40; H, 2.97; N, 7.38; S, 9.23.
3-(4-Methylphenyl)-4,5-dimethyl-1,3-thiazolium
Hexafluorophosphate (21). According to general procedure B, 2.35
g (10 mmol) of 3-aryl-4,5-dimethylthiazole-2-thione 9 in 25 mL of
AcOH was treated with 3.06 mL of H2O2 (30 mmol). Following
general procedure B the oil was dissolved in 20 mL of MeOH, and a
mixture of 40 mL of MeOH/water (1:1) and 3.68 g of KPF6 (20
mmol, 2 equiv) was added. After extraction the precipitated solid was
filtered and washed with ether before drying under high vacuum.
Compound 21 was obtained as a pale brown solid (1.74 g, 49.8%).
3.61; N, 4.18; S, 9.56. Found: C, 39.67; H, 3.26; N, 4.22; S, 9.77.
3-(4-Bromophenyl)-4,5-dimethyl-1,3-thiazolium Perchlorate
(17). According to general procedure B 2.99 g (10 mmol) of 3-aryl-
4,5-dimethylthiazole-2-thione 9 in 25 mL of AcOH was treated with
3.06 mL of H2O2 (30 mmol). Following general procedure B the oil
was dissolved in 20 mL of MeOH, and a mixture of 40 mL of MeOH/
water (1:1) and 2.81 g of NaClO4·H2O (20 mmol, 2 equiv) was added.
After extraction the precipitated solid was filtered and washed with
ether before drying under high vacuum. Compound 17 was obtained
1
1
as a brown solid (2.04 g, 55.4%). Mp: 131−134 °C. H NMR (300
Mp: 116−118 °C. H NMR (300 MHz, DMSO-d6): δ 2.20 (s, 3H,
MHz, DMSO-d6): δ 2.22 (s, 3H, CH3), 2.59 (s, 3H, CH3), 7.69 (d, J =
8.7 Hz, 2H, CHarom), 7.94 (d, J = 8.7 Hz, 2H, CHarom.), 10.25 (s, 1H,
N(CH)S). 13C NMR (75 MHz, DMSO-d6): δ 157.41 (N(CH)S),
142.01 (Ci), 136.15 (Ci), 132.86 (2C, CHarom), 132.68 (Ci), 128.41
(2C, CHarom), 124.69 (Ci), 11.96 (CH3), 11.88 (CH3). MS (ESI): m/z
CH3), 2.44 (s, 3H, CH3), 2.58 (s, 3H, CH3), 7.50 (d, J = 8.5 Hz, 2H,
CHarom), 7.58 (d, J = 8.4 Hz, 2H, CHarom), 10.21 (s, 1H, N(CH)S).
13C NMR (75 MHz, DMSO-d6): δ 156.97 (N(CH)S), 142.18 (Ci),
141.27 (Ci), 134.57 (Ci), 132.58 (Ci), 130.26 (2C, CHarom.), 125.83
(2C, CHarom.), 20.67 (CH3), 11.99 (CH3), 11.91 (CH3). MS (ESI): m/
−
(fragment) 268.0 (M+), 636.9 (2[NHC]+ + ClO4 ). Anal. Calcd for
−
z (fragment) 204.0 ([NHC]+), 552.9 (2[NHC]+ + PF6 ). Anal. Calcd
C11H11BrClNO4S: C, 35.84; H, 3.01; N, 3.80; S, 8.70. Found: C,
36.23; H, 2.98; N, 3.70; S, 8.99.
for C12H14F6NPS: C 41.26; H 4.04; N 4.01; S 9.53. Found: C 41.33; H
4.11; N 4.00; S 9.52.
3-(4-Bromophenyl)-4,5-dimethyl-1,3-thiazolium
Hexafluorophosphate (18). According to general procedure B 1.49
g (5 mmol) of 3-aryl-4,5-dimethylthiazole-2-thione 9 in 13 mL of
AcOH was treated with 1.53 mL of H2O2 (15 mmol). Following
general procedure B the oil was dissolved in 10 mL of MeOH, and a
mixture of 20 mL of MeOH/water (1:1) and 1.84 g of KPF6 (20
mmol, 2 equiv) was added. After extraction the precipitated solid was
filtered and washed with ether before drying under high vacuum.
Compound 18 was obtained as a brown solid (631 mg, 30.5%). Mp:
3-(4-Benzoic acid methyl ester)-4,5-dimethyl-1,3-thiazolium
Hexafluorophosphate (22). According to general procedure B 2.79
g (10 mmol) of 3-aryl-4,5-dimethylthiazole-2-thione 9 in 25 mL of
AcOH was treated with 3.06 mL of H2O2 (30 mmol). Following
general procedure B the oil was dissolved in 20 mL of MeOH, and a
mixture of 40 mL of MeOH/water (1:1) and 3.68 g of KPF6 (20
mmol, 2 equiv) was added. After extraction the precipitated solid was
filtered and washed with ether before drying under high vacuum.
Compound 22 was obtained as a brown solid (1.01 g, 25.6%). Mp:
1
1
162−166 °C. H NMR (300 MHz, DMSO-d6): δ 2.21 (s, 3H, CH3),
130−132 °C. H NMR (300 MHz, DMSO-d6): δ 2.21 (s, 3H, CH3),
2.58 (s, 3H, CH3), 7.68 (d, J = 8.6 Hz, 2H, CHarom), 7.93 (d, J = 8.6
Hz, 2H, CHarom.), 10.24 (s, 1H, N(CH)S). 13C NMR (75 MHz,
DMSO-d6): δ 157.43 (N(CH)S), 142.00 (Ci), 136.15 (Ci), 132.85
(2C, CHarom), 132.66 (Ci), 128.41 (2C, CHarom), 124.69 (Ci), 11.95
(CH3), 11.87 (CH3). MS (ESI): m/z (fragment): 268.0 (M+), 680.7
2.59 (s, 3H, CH3), 3.93 (s, 3H, CH3), 7.87 (d, J = 8.4 Hz, 2H,
CHarom), 8.24 (d, J = 8.4 Hz, 2H, CHarom), 10.30 (s, 1H, N(CH)S).
13C NMR (75 MHz, DMSO-d6): δ 165.05 (CO), 157.44 (N(CH)S),
141.89 (Ci), 140.37 (Ci), 132.89 (Ci), 132.04 (Ci), 130.63 (2C,
CHarom), 126.94 (2C, CHarom), 52.65 (CO2CH3), 11.94 (CH3), 11.88
I
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(CH3). MS (ESI): m/z (fragment) 248.1 ([NHC]+). Anal. Calcd for
C13H14F6NO2PS: C, 39.70; H, 3.59; N, 3.56; S, 8.15. Found: C, 39.77;
H, 3.60; N, 3.57; S, 8.46.
and workup steps yielded complex 25 as a bright yellow powder (69
mg, 17.8%). The improved synthesis (general procedure D) using 536
mg (1.6 mmol) of 3-aryl-4,5-dimethylthiazolium salt 16, 204 mg of
Ag2O (0.88 mmol, 0.55 equiv), 598 mg of Pt(COD)Cl2 (1.6 mmol, 1
equiv), 640 mg of acetylacetonate (6.4 mmol, 4.0 equiv), and 884 mg
of K2CO3 (6.4 mmol, 4.0 equiv) in 40 mL of dry DMF gave a bright
3-(3-Methylphenyl)-4,5-dimethyl-1,3-thiazolium Perchlorate
(23). According to general procedure B, 3.53 g (15 mmol) of 3-aryl-
4,5-dimethylthiazole-2-thione 14 in 39 mL of AcOH was treated with
4.59 mL of H2O2 (45 mmol). Following general procedure B the oil
was dissolved in 20 mL of MeOH, and a mixture of 60 mL of MeOH/
water (1:1) and 4.21 g of NaClO4·H2O (30 mmol, 2 equiv) was added.
After extraction no solid could be precipitated. Further purification by
column chromatography using a dichloromethane/methanol (10:1)
mixture yielded a crude oil, which crystallized overnight. Further
stirring of the crude solid in diethyl ether for 24 h and subsequent
filtration gave compound 23 as a pale brown solid (1.31 g, 21.5%).
Mp: 70−71 °C. 1H NMR (300 MHz, DMSO-d6): δ 2.21 (s, 3H, CH3),
2.43 (s, 3H, CH3), 2.58 (s, 3H, CH3), 7.37−7.70 (m, 5H, CHarom),
10.23 (s, 1H, N(CH)S). 13C NMR (75 MHz, DMSO-d6): δ 156.92
(N(CH)S), 142.00 (Ci), 139.90 (Ci), 136.92 (Ci), 132.66 (Ci), 131.80
(CHarom), 129.71 (CHarom), 126.40 (CHarom), 123.10 (CHarom), 20.66
(CH3), 12.00 (CH3), 11.92 (CH3). MS (ESI): m/z (fragment) 204.0
([NHC]+), 507.0 (2[NHC]+ + ClO4−). Anal. Calcd for
C12H14ClNO4S: C, 47.45; H, 4.65; N, 4.61; S, 10.56. Found: C,
47.82; H, 4.81; N, 4.65; S, 10.47.
1
yellow powder (260 mg, 33.7%). Mp: 294−295 °C. H NMR (300
MHz, CDCl3): δ 2.03 (s, 3H, CH3), 2.06 (s, 3H, CH3), 2.26 (s, 3H,
CH3), 2.70 (s, 3H, CH3), 5.49 (s, 1H, CHacac), 6.97−7.16 (m, 2H,
CHarom), 7.32−7.48 (m, 1H, CHarom), 7.73−8.02 (m, 1H, CHarom). 13
C
NMR (75 MHz, CDCl3): δ 186.30 (CO), 185.30 (CO), 178.00
(NCS), 151.35 (Ci-Pt), 136.96 (Ci), 132.53 (CHarom.), 127.76 (Ci),
125.53 (CHarom.), 123.60 (Ci), 123.37 (CHarom.), 113.40 (CHarom.),
102.39 (CHarom.;acac), 28.01 (CH3;acac), 27.85 (CH3;acac), 14.12 (CH3),
12.67 (CH3). 195Pt NMR (64 MHz, CDCl3): δ −3346.22. Anal. Calcd
for C16H17NO2PtS: C, 39.83; H, 3.55; N, 2.90; S, 6.65. Found: C,
39.77; H, 3.70; N, 2.75; S, 6.63.
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-(4-bromo-
phenyl)-κC′-1,3-thiazole-2-ylidene-κC]platinum(II) (26). Accord-
ing to general procedure C 20 mL of dry 1,4-dioxane was added to a
mixture of 331 mg (0.8 mmol) of 3-aryl-4,5-dimethylthiazolium salt 18
and 102 mg of Ag2O (0.44 mmol, 0.55 equiv). Stepwise addition of
299 mg of Pt(COD)Cl2 (0.8 mmol, 1 equiv), 320 mg of
acetylacetonate (3.2 mmol, 4.0 equiv), and 370 mg of KOtBu (3.2
mmol, 4.0 equiv) and following general procedure C in temperature
and workup steps yielded complex 26 as a bright yellow powder (71
mg, 15.8%). The improved synthesis (general procedure D) using 166
mg (0.4 mmol) of 3-aryl-4,5-dimethylthiazolium salt 18, 51 mg of
Ag2O (0.22 mmol, 0.55 equiv), 150 mg of Pt(COD)Cl2 (0.8 mmol, 1
equiv), 160 mg of acetylacetonate (1.6 mmol, 4.0 equiv), and 221 mg
of K2CO3 (1.6 mmol, 4.0 equiv) in 10 mL of dry DMF gave a bright
3-(3-Methylphenyl)-4,5-dimethyl-1,3-thiazolium
Hexafluorophosphate (24). According to general procedure B, 1.18
g (5 mmol) of 3-aryl-4,5-dimethylthiazole-2-thione 14 in 13 mL of
AcOH was treated with 1.53 mL of H2O2 (15 mmol). Following
general procedure B the oil was dissolved in 10 mL of MeOH, and a
mixture of 20 mL of MeOH/water (1:1) and 1.84 g of KPF6 (20
mmol, 2 equiv) was added. After extraction the precipitated solid was
filtered and washed with ether before drying under high vacuum.
Compound 23 was obtained as a pale brown solid (739 mg, 42.3%).
Mp: 86−88 °C. 1H NMR (300 MHz, DMSO-d6): δ 2.21 (s, 3H, CH3),
2.43 (s, 3H, CH3), 2.58 (s, 3H, CH3), 7.37−7.70 (m, 5H, CHarom),
10.23 (s, 1H, N(CH)S). 13C NMR (75 MHz, DMSO-d6): δ 156.95
(N(CH)S), 141.99 (Ci), 139.89 (Ci), 136.92 (Ci), 132.64 (Ci), 131.79
(CHarom.), 129.70 (CHarom.), 126.39 (CHarom.), 123.09 (CHarom.), 20.65
(CH3), 11.97 (CH3), 11.90 (CH3). MS (ESI): m/z (fragment) 204.0
1
yellow powder (122 mg, 54.3%). Mp: 277−279 °C. H NMR (300
MHz, CDCl3): δ 2.03 (s, 3H, CH3), 2.08 (s, 3H, CH3), 2.27 (s, 3H,
CH3), 2.65 (s, 3H, CH3), 5.50 (s, 1H, CHacac), 7.16 (dd, J = 8.6, J = 2.2
Hz, 1H, CHarom), 7.20−7.28 (partially omitted by solvent signal, m, 1H,
CHarom), 7.77−8.05 (m, 1H, CHarom). 13C NMR (75 MHz, CDCl3): δ
186.29 (CO), 185.51 (CO), 177.75 (NCS), 150.19 (Ci-Pt), 136.85
(Ci), 134.65 (CHarom), 131.09 (Ci), 125.84 (CHarom), 124.05 (Ci),
119.25 (Ci), 114.68 (CHarom), 102.51 (CHarom;acac), 27.93 (CH3;acac),
27.88 (CH3;acac), 14.01 (CH3), 12.67 (CH3). 195Pt NMR (64 MHz,
CDCl3): δ −3313.03. Anal. Calcd for C16H16BrNO2PtS: C, 34.17; H,
3.05; N, 2.49; S, 5.70. Found: C, 34.42; H, 2.84; N, 2.56; S, 5.76.
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-(4-
methoxyphenyl)-κC′-1,3-thiazole-2-ylidene-κC]platinum(II)
(27). According to general procedure C 20 mL of dry 1,4-dioxane was
added to a mixture of 292 mg (0.8 mmol) of 3-aryl-4,5-
dimethylthiazolium salt 19 and 102 mg of Ag2O (0.44 mmol, 0.55
equiv). Stepwise addition of 299 mg of Pt(COD)Cl2 (0.8 mmol, 1
equiv), 320 mg of acetylacetonate (3.2 mmol, 4.0 equiv), and 370 mg
of KOtBu (3.2 mmol, 4.0 equiv) and following general procedure C in
temperature and workup steps yielded complex 27 as a bright yellow
powder (85 mg, 20.7%). The improved synthesis (general procedure
D) using 146 mg (0.4 mmol) of 3-aryl-4,5-dimethylthiazolium salt 19,
51 mg of Ag2O (0.22 mmol, 0.55 equiv), 150 mg of Pt(COD)Cl2 (0.8
mmol, 1 equiv), 160 mg of acetylacetonate (1.6 mmol, 4.0 equiv), and
221 mg of K2CO3 (1.6 mmol, 4.0 equiv) in 10 mL of dry DMF gave a
−
([NHC]+), 553.0 (2[NHC]+ + PF6 ). Anal. Calcd for C12H14F6NPS:
C, 41.26; H, 4.04; N, 4.01; S, 9.18. Found: C, 41.46; H, 4.01; N, 4.23;
S, 9.55.
General Procedures C and D: Thiazole-2-ylidene Pt(II)
Complexes. The general procedure C employed in this study starts
by adding 25 mL/mmol of dry 1,4-dioxane to a mixture of 3-aryl-4,5-
dimethylthiazolium salt and 0.55 equiv of Ag2O in a dry Schlenk tube.
The resulting solution was stirred at room temperature for 2 h and for
22 h at 50 °C under the exclusion of light. After addition of 13 mL/
mmol of 2-butanone and 1 equiv of Pt(COD)Cl2 a further 2 h of
stirring at room temperature was followed by 22 h of stirring at 115
°C. The solvent was removed in vacuo, and 25 mL/mmol of dry DMF,
4.0 equiv of acetylacetonate, and 4.0 equiv of KOtBu were added.
Afterward the final mixture was stirred at room temperature for 24 h
and then heated to 100 °C for 6 h. All volatiles were removed in vacuo,
and the remaining solid was dispersed in 50 mL of distilled water and
filtered. The solid residue was dissolved in dichloromethane and the
complex isolated by flash column chromatography using pure
dichloromethane as the eluent. Subsequent washing with isohexanes
and diethyl ether yielded the pure complexes. The improved synthesis
(general procedure D) followed the same time−temperature sequence
but solely uses DMF as the solvent and K2CO3 as the base for
deprotonation of the acetylacetonate ligand. Washing and purification
remain the same as described above.
1
bright yellow powder (69 mg, 33.7%). Mp: 264−268 °C. H NMR
(300 MHz, CDCl3): δ 2.02 (s, 3H, CH3), 2.05 (s, 3H, CH3), 2.26 (s,
3H, CH3), 2.66 (s, 3H, CH3), 3.86 (s, 3H, CH3), 5.48 (s, 1H, CHacac),
6.56 (dd, J = 8.8 Hz, J = 2.9 Hz, 1H, CHarom), 7.31 (d, J = 8.8 Hz, 1H,
CHarom), 7.35−7.56 (m, 1H, CHarom). 13C NMR (75 MHz, CDCl3): δ
186.23 (CO), 185.25 (CO), 175.38 (NCS), 156.82 (Ci-Pt), 145.08
(Ci), 136.65 (Ci), 129.86 (Ci), 123.56 (Ci), 117.40 (CHarom), 114.17
(CHarom), 107.85 (CHarom), 102.40 (CHarom;acac), 55.32 (OCH3), 27.99
(CH3;acac), 27.86 (CH3;acac), 13.94 (CH3), 12.66 (CH3). 195Pt NMR
(64 MHz, CDCl3): δ −3330.75. Anal. Calcd for C17H19NO3PtS: C,
39.76; H, 3.93; N, 2.73; S, 6.24. Found: C, 39.90; H, 3.85; N, 2.74; S,
6.28.
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-phenyl-
κC′-1,3-thiazole-2-ylidene-κC]platinum(II) (25). According to
general procedure C 20 mL of dry 1,4-dioxane was added to a
mixture of 268 mg (0.8 mmol) of 3-aryl-4,5-dimethylthiazolium salt 15
and 102 mg of Ag2O (0.44 mmol, 0.55 equiv). Stepwise addition of
299 mg of Pt(COD)Cl2 (0.8 mmol, 1 equiv), 320 mg of
acetylacetonate (3.2 mmol, 4.0 equiv), and 370 mg of KOtBu (3.2
mmol, 4.0 equiv) and following general procedure C in temperature
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-(4-cyano-
phenyl)-κC′-1,3-thiazole-2-ylidene-κC]platinum(II) (28). Accord-
J
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
ing to general procedure C 20 mL of dry 1,4-dioxane was added to a
mixture of 288 mg (0.8 mmol) of 3-aryl-4,5-dimethylthiazolium salt 20
and 102 mg of Ag2O (0.44 mmol, 0.55 equiv). Stepwise addition of
299 mg of Pt(COD)Cl2 (0.8 mmol, 1 equiv), 320 mg of
acetylacetonate (3.2 mmol, 4.0 equiv), and 370 mg of KOtBu (3.2
mmol, 4.0 equiv) and following general procedure C in temperature
and workup steps yielded complex 28 as a bright yellow powder (86
mg, 20.7%). The improved synthesis (general procedure D) using 144
mg (0.4 mmol) of 3-aryl-4,5-dimethylthiazolium salt 20, 51 mg of
Ag2O (0.22 mmol, 0.55 equiv), 150 mg of Pt(COD)Cl2 (0.8 mmol, 1
equiv), 160 mg of acetylacetonate (1.6 mmol, 4.0 equiv), and 221 mg
of K2CO3 (1.6 mmol, 4.0 equiv) in 10 mL of dry DMF gave a bright
299 mg of Pt(COD)Cl2 (0.8 mmol, 1 equiv), 320 mg of
acetylacetonate (3.2 mmol, 4.0 equiv), and 442 mg of K2CO3 (3.2
mmol, 4.0 equiv) and following general procedure C in temperature
and workup steps yielded complex 31 as a bright yellow powder (95
1
mg, 23.9%). Mp: 318 °C (dec). H NMR (300 MHz, CDCl3): δ 2.02
(s, 3H, CH3), 2.05 (s, 3H, CH3), 2.27 (s, 3H, CH3), 2.35 (s, 3H, CH3),
2.70 (s, 3H, CH3), 5.48 (s, 1H, CHacac), 6.94 (d, J = 6.8 Hz, 1H,
CHarom), 7.17−7.31 (partially under solvent signal, m, 1H, CHarom),
7.58−7.86 (m, 1H, CHarom). 13C NMR (75 MHz, CDCl3): δ 186.21
(CO), 185.26 (CO), 178.12 (Ci), 136.93 (Ci), 132.79 (CHarom),
132.28 (Ci), 126.13 (CHarom), 123.44 (Ci), 123.37 (Ci), 114.53
(CHarom), 102.36 (CHarom;acac), 28.03 (CH3;acac), 27.85 (CH3;acac),
21.72 (CH3), 14.19 (CH3), 12.70 (CH3). 195Pt NMR (64 MHz,
CDCl3): δ −3342.70. Anal. Calcd for C17H19NO2PtS: C, 41.13; H,
3.86; N, 2.82; S, 6.46. Found: C, 40.91; H, 3.98; N, 2.78; S, 6.35.
1
yellow powder (63 mg, 31.0%). Mp: 330 °C (dec). H NMR (300
MHz, CDCl3): δ 2.05 (s, 3H, CH3), 2.10 (s, 3H, CH3), 2.30 (s, 3H,
CH3), 2.70 (s, 3H, CH3), 5.53 (s, 1H, CHacac), 7.35 (dd, J = 8.4 Hz, J =
1.9 Hz, 1H, CHarom), 7.44 (d, J = 8.5 Hz, 1H, CHarom), 7.99−8.26 (m,
1H, CHarom). 13C NMR (75 MHz, CDCl3): δ 186.54 (CO), 185.69
(CO), 176.72 (NCS), 136.92 (Ci), 135.51 (CHarom), 129.69 (Ci),
128.04 (CHarom), 124.59 (Ci), 119.61 (Ci), 113.22 (CHarom), 108.49
(Ci), 102.66 (CHarom;acac), 27.92 (CH3;acac), 27.83 (CH3;acac), 14.16
(CH3), 12.70(CH3). 195Pt NMR (64 MHz, CDCl3): δ −3311.01. Anal.
Calcd for C17H16N2O2PtS: C, 40.24; H, 3.18; N, 5.52; S, 6.32. Found:
C, 40.15; H, 3.15; N, 5.50; S, 6.28.
ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.5b00991.
List of abbreviations, photoluminescence data, details of
the quantum chemical calculations including xyz-
coordinates, and detailed 2D-NMR spectra (PDF)
Crystallographic data (CIF)
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-(4-methyl-
phenyl)-κC′-1,3-thiazole-2-ylidene-κC]platinum(II) (29). Accord-
ing to general procedure D, 20 mL of dry DMF was added to a
mixture of 279 mg (0.8 mmol) of 3-aryl-4,5-dimethylthiazolium salt 21
and 102 mg of Ag2O (0.44 mmol, 0.55 equiv). Stepwise addition of
299 mg of Pt(COD)Cl2 (0.8 mmol, 1 equiv), 320 mg of
acetylacetonate (3.2 mmol, 4.0 equiv), and 442 mg of K2CO3 (3.2
mmol, 4.0 equiv) and following general procedure C in temperature
and workup steps yielded complex 29 as a bright yellow powder (110
Optimized Cartesian coordinates (XYZ)
AUTHOR INFORMATION
Corresponding Author
*Fax: 49 351 46339679. Tel: 49 351 46338571. E-mail: thomas.
strassner@chemie.tu-dresden.de.
■
1
mg, 27.7%). Mp: 268−269 °C. H NMR (300 MHz, CDCl3): δ 2.02
(s, 3H, CH3), 2.08 (s, 3H, CH3), 2.26 (s, 3H, CH3), 2.37 (s, 3H, CH3),
2.67 (s, 3H, CH3), 5.48 (s, 1H, CHacac), 6.83 (dd, J = 8.2 Hz, J = 1.3
Hz, 1H, CHarom), 7.23−7.31 (partially under solvent signal, m, 1H,
CHarom), 7.52−7.80 (m, 1H, CHarom). 13C NMR (75 MHz, CDCl3): δ
186.25 (CO), 185.30 (CO), 177.05 (NCS), 149.09 (Ci-Pt), 136.84
(Ci), 135.30 (Ci), 133.09 (CHarom.), 127.37 (Ci), 123.68 (Ci), 123.49
(CHarom), 113.31 (CHarom), 102.39 (CHarom;acac), 28.02 (CH3;acac),
27.90 (CH3;acac), 21.22 (CH3), 14.05 (CH3), 12.66 (CH3). 195Pt NMR
(64 MHz, CDCl3): δ −3340.04. Anal. Calcd for C17H19NO2PtS: C,
41.13; H, 3.86; N, 2.82; S, 6.46. Found: C, 40.73; H, 3.69; N, 2.87; S,
6.31.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful for the services and the generous allocation of
computer time by the ZIH on their high-performance
computing facility.
REFERENCES
■
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-(4-benzoic
acid methyl ester)-κC′-1,3-thiazole-2-ylidene-κC]platinum(II)
(30). According to general procedure D, 20 mL of dry DMF was
added to a mixture of 315 mg (0.8 mmol) of 3-aryl-4,5-
dimethylthiazolium salt 22 and 102 mg of Ag2O (0.44 mmol, 0.55
equiv). Stepwise addition of 299 mg of Pt(COD)Cl2 (0.8 mmol, 1
equiv), 320 mg of acetylacetonate (3.2 mmol, 4.0 equiv), and 442 mg
of K2CO3 (3.2 mmol, 4.0 equiv) and following general procedure C in
temperature and workup steps yielded complex 30 as a bright yellow
(1) (a) Martin-Smith, M.; Reid, S. T. J. Med. Pharm. Chem. 1959, 1,
507−564. (b) Gibson, D. T. Chem. Rev. 1934, 14, 431−457.
(c) Kausar, A.; Zulfiqar, S.; Sarwar, M. I. Polym. Rev. 2014, 54,
185−267.
(2) (a) Perepichka, I. F.; Perepichka, D. F. Handbook of Thiophene-
Based Materials; John Wiley & Sons, Ltd: Chichester, UK, 2009.
(b) Cinar, M. E.; Ozturk, T. Chem. Rev. 2015, 115, 3036−3140.
(3) (a) Jin, Z. Nat. Prod. Rep. 2011, 28, 1143−1191. (b) Davyt, D.;
Serra, G. Mar. Drugs 2010, 8, 2755−2780.
(4) (a) Ayati, A.; Emami, S.; Asadipour, A.; Shafiee, A.; Foroumadi,
A. Eur. J. Med. Chem. 2015, 97, 699−718. (b) Mishra, C. B.; Kumari,
S.; Tiwari, M. Eur. J. Med. Chem. 2015, 92, 1−34.
(5) Malandrinos, G.; Louloudi, M.; Hadjiliadis, N. Chem. Soc. Rev.
2006, 35, 684−692.
1
powder (202 mg, 46.7%). Mp: 276−278 °C. H NMR (300 MHz,
CDCl3): δ 2.03 (s, 3H, CH3), 2.11 (s, 3H, CH3), 2.24 (s, 3H, CH3),
2.65 (s, 3H, CH3), 3.92 (s, 3H, CH3), 5.50 (s, 1H, CHacac), 7.31−7.46
(m, 1H, CHarom), 7.71 (dd, J = 8.5 Hz, J = 2.0 Hz, 1H, CHarom), 8.31−
8.60 (m, 1H, CHarom). 13C NMR (75 MHz, CDCl3): δ 186.24 (CO),
185.56 (CO), 179.67 (CO), 167.35 (Ci), 154.87 (Ci), 136.98 (Ci),
133.09 (CHarom), 127.94 (Ci), 126.48 (Ci), 125.80 (CHarom), 124.06
(Ci), 112.86 (CHarom), 102.46 (CHarom;acac), 51.90 (CO2CH3), 27.94
(CH3;acac), 27.90 (CH3;acac), 14.15 (CH3), 12.63 (CH3). 195Pt NMR
(64 MHz, CDCl3): δ −3320.80 (d, J = 49.0 Hz). Anal. Calcd for
C18H19NO4PtS: C, 40.00; H, 3.54; N, 2.59; S, 5.93. Found: C, 39.68;
H, 3.47; N, 2.64; S, 6.31.
(6) (a) Flanigan, D. M.; Romanov-Michailidis, F.; White, N. A.;
Rovis, T. Chem. Rev. 2015, 115, 9307−9387. (b) Enders, D.; Niemeier,
O.; Henseler, A. Chem. Rev. 2007, 107, 5606−5655. (c) Yetra, S. R.;
Patra, A.; Biju, A. T. Synthesis 2015, 47, 1357−1378. (d) Benhamou,
́
L.; Chardon, E.; Lavigne, G.; Bellemin-Laponnaz, S.; Cesar, V. Chem.
Rev. 2011, 111, 2705−2733. (e) Wang, G.; Chen, X.; Zhang, Y.; Yao,
W.; Ma, C. Org. Lett. 2013, 15, 3066−3069. (f) Kuhl, N.; Glorius, F.
Chem. Commun. 2011, 47, 573−575. (g) Ahire, M. M.; Mhaske, S. B.
Angew. Chem., Int. Ed. 2014, 53, 7038−7042.
(SP-4-4)-Acetylacetonato-κO,κO′-[4,5-dimethyl-3-(5-methyl-
phenyl)-κC′-1,3-thiazole-2-ylidene-κC]platinum(II) (31). Accord-
ing to general procedure D, 20 mL of dry DMF was added to a
mixture of 279 mg (0.8 mmol) of 3-aryl-4,5-dimethylthiazolium salt 24
and 102 mg of Ag2O (0.44 mmol, 0.55 equiv). Stepwise addition of
(7) (a) Vougioukalakis, G. C.; Grubbs, R. H. Olefin Metathesis
initiatiors bearing thiazol-2-ylidene ligands. WO2008064223A1, 2008.
K
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(b) Vougioukalakis, G. C.; Grubbs, R. H. J. Am. Chem. Soc. 2008, 130,
2234−2245.
6, 251−260. (c) Vozka, J.; Kalíkova,
́
K.; Roussel, C.; Armstrong, D.
W.; Tesarova, E. J. Sep. Sci. 2013, 36, 1711−1719. (d) Sattigeri, V. J.;
̌
́
(8) Mendoza-Espinosa, D.; Ung, G.; Donnadieu, B.; Bertrand, G.
Chem. Commun. 2011, 47, 10614−10616.
Soni, A.; Singhal, S.; Khan, S.; Pandya, M.; Bhateja, P.; Mathur, T.;
Rattan, A.; Khanna, J. M.; Mehta, A. ARKIVOC 2005, 2, 46−49.
(e) Pirkle, W. H.; Brice, L. J.; Terfloth, G. J. J. Chromatogr. A 1996,
753, 109−119. (f) Wang, Z.; Yu, Z.; Wang, Y.; Shi, D. Synthesis 2012,
44, 1559−1568.
(9) Zhang, J.; Fu, J.; Su, X.; Qin, X.; Zhao, M.; Shi, M. Chem.
Commun. 2012, 48, 9625−9627.
(10) (a) Djurovich, P. I.; Murphy, D.; Thompson, M. E.; Hernandez,
B.; Gao, R.; Hunt, P. L.; Selke, M. Dalton Trans. 2007, 3763−3770.
(b) Hui, H.; Wei, L.; Zhentao, L.; Xiangen, H. Spectrochim. Acta, Part
A 2015, 142, 271−278.
(11) (a) Adamovich, V.; Brooks, J.; Tamayo, A.; Alexander, A. M.;
Djurovich, P. I.; D’Andrade, B. W.; Adachi, C.; Forrest, S. R.;
Thompson, M. E. New J. Chem. 2002, 26, 1171−1178. (b) Blight, B.
A.; Ko, S.-B.; Lu, J.-S.; Smith, L. F.; Wang, S. Dalton Trans. 2013, 42,
10089−10092. (c) Bossi, A.; Rausch, A. F.; Leitl, M. J.; Czerwieniec,
R.; Whited, M. T.; Djurovich, P. I.; Yersin, H.; Thompson, M. E. Inorg.
Chem. 2013, 52, 12403−12415.
(26) (a) Pirkle, W. H.; Koscho, M. E.; Wu, Z. J. Chromatogr. A 1996,
726, 91−97. (b) Roussel, C.; Adjimi, M.; Chemlal, A.; Djafri, A. J. Org.
Chem. 1988, 53, 5076−5080. (c) Roussel, C.; Favrou, A. J. Inclusion
Phenom. Mol. Recognit. Chem. 1993, 16, 283−296. (d) Roussel, C.;
Vanthuyne, N.; Bouchekara, M.; Djafri, A.; Elguero, J.; Alkorta, I. J.
Org. Chem. 2008, 73, 403−411. (e) Roussel, C.; Rafii, E.; Del Rio, A.;
Vanthuyne, N. Biomed. Chromatogr. 2005, 19, 434−438.
́
(27) (a) Bellec, N.; Guerin, D.; Lorcy, D.; Robert, A.; Carlier, R.;
Tallec, A. Acta Chem. Scand. 1999, 53, 861−866. (b) Roussel, C.;
Suteu, C. J. Chromatogr. A 1997, 761, 129−138. (c) Tripathy, H.; Das,
M. K.; Sahu, B.; Dash, B. C.; Mahapatra, G. N. J. Indian Chem. Soc.
(12) (a) Fernan
́ ́ ́
dez-Hernandez, J. M.; Beltran, J. I.; Lemaur, V.;
Galvez-Lopez, M.-D.; Chien, C.-H.; Polo, F.; Orselli, E.; Frohlich, R.;
́
́
̈
1973, 1, 417−419. (d) Ruhlmann, K.; Grosalski, A.; Schrapler, U. J.
̈
̈
Cornil, J.; De Cola, L. Inorg. Chem. 2013, 52, 1812−1824. (b) Smith,
A. R. G.; Riley, M. J.; Burn, P. L.; Gentle, I. R.; Lo, S. C.; Powell, B. J.
Inorg. Chem. 2012, 51, 2821−2831.
Prakt. Chem. 1960, 11, 54−62.
(28) Opitz, G. Angew. Chem. 1967, 79, 161−177.
(29) Loosmore, S. M.; McKinnon, D. M. Oxidation Products of
(13) (a) Sajoto, T.; Djurovich, P. I.; Tamayo, A.; Yousufuddin, M.;
Bau, R.; Thompson, M. E.; Holmes, R. J.; Forrest, S. R. Inorg. Chem.
2005, 44, 7992−8003. (b) Wu, W.; Guo, H.; Wu, W.; Ji, S.; Zhao, J.
Inorg. Chem. 2011, 50, 11446−11460.
(14) (a) Kozhevnikov, D. N.; Kozhevnikov, V. N.; Shafikov, M. Z.;
Prokhorov, A. M.; Bruce, D. W.; Williams, J. A. G. Inorg. Chem. 2011,
50, 3804−3815. (b) Fischer, T.; Czerwieniec, R.; Hofbeck, T.;
Osminina, M. M.; Yersin, H. Chem. Phys. Lett. 2010, 486, 53−59.
(c) Fan, C.; Yang, C. Chem. Soc. Rev. 2014, 43, 6439−6469.
(15) (a) Wang, R.; Liu, D.; Ren, H.; Zhang, T.; Wang, X.; Li, J. J.
Mater. Chem. 2011, 21, 15494−15500. (b) Giridhar, T.; Cho, W.; Kim,
Y.-H.; Han, T.-H.; Lee, T.-W.; Jin, S.-H. J. Mater. Chem. C 2014, 2,
9398−9405.
Cyclic Thiones. Phosphorus Sulfur Relat. Elem. 1976, 1, 185−209.
(30) Unger, Y.; Meyer, D.; Molt, O.; Schildknecht, C.; Munster, I.;
Wagenblast, G.; Strassner, T. Angew. Chem., Int. Ed. 2010, 49, 10214−
10216.
̈
́
(31) Fuertes, S.; García, H.; Peralvarez, M.; Hertog, W.; Carreras, J.;
Sicilia, V. Chem. - Eur. J. 2015, 21, 1620−1631.
(32) (a) Tronnier, A.; Metz, S.; Wagenblast, G.; Muenster, I.;
Strassner, T. Dalton Trans. 2014, 43, 3297−3305. (b) Tronnier, A.;
Nischan, N.; Metz, S.; Wagenblast, G.; Munster, I.; Strassner, T. Eur. J.
̈
Inorg. Chem. 2014, 2014, 256−264.
(33) Tronnier, A.; Poethig, A.; Herdtweck, E.; Strassner, T.
Organometallics 2014, 33, 898−908.
(34) Unger, Y.; Strassner, T.; Lennartz, C. J. Organomet. Chem. 2013,
748, 63−67.
(16) (a) Mydlak, M.; Yang, C.-H.; Polo, F.; Galstyan, A.; Daniliuc, C.
G.; Felicetti, M.; Leonhardt, J.; Strassert, C. A.; De Cola, L. Chem. -
Eur. J. 2015, 21, 5161−5172. (b) Brooks, J.; Babayan, Y.; Lamansky,
S.; Djurovich, P. I.; Tsyba, I.; Bau, R.; Thompson, M. E. Inorg. Chem.
2002, 41, 3055−3066.
(35) Drew, D.; Doyle, J. R.; Shaver, A. G. Cyclic Diolefin Complexes
of Platinum and Palladium. In Inorganic Synthesis; John Wiley & Sons,
Inc.: New York, 2007; pp 346−349.
(36) Gansauer, A.; Behlendorf, M.; von Laufenberg, D.; Fleckhaus,
̈
(17) Visbal, R.; Gimeno, M. C. Chem. Soc. Rev. 2014, 43, 3551−3574.
(18) (a) Haneder, S.; Da Como, E.; Feldmann, J.; Lupton, J. M.;
A.; Kube, C.; Sadasivam, D. V.; Flowers, R. A. Angew. Chem., Int. Ed.
2012, 51, 4739−4742.
Lennartz, C.; Erk, P.; Fuchs, E.; Molt, O.; Munster, I.; Schildknecht,
̈
(37) Sheldrick, G. M. SADABS, Version 2.10; University of
Goettingen: Goettingen, Germany, 2002.
C.; Wagenblast, G. Adv. Mater. 2008, 20, 3325−3330. (b) Hudson, Z.
M.; Sun, C.; Helander, M. G.; Chang, Y.-L.; Lu, Z.-H.; Wang, S. J. Am.
Chem. Soc. 2012, 134, 13930−13933.
(38) (a) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J. Appl. Crystallogr. 1994, 27,
435. (b) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.;
Spagna, R. J. Appl. Crystallogr. 1999, 32, 115−119.
(39) Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr.
2008, 64, 112−122.
(40) Wilson, A. J. C. Ed. Mathematical, Physical and Chemical Tables,
International Tables for Crystallography, Vol. C; Kluwer, 1992.
(41) Hooft, R. W. W. Collect, Data Collection Software for Nonius-
Kappa CCD; Nonius B.V.: Delft, The Netherlands, 1999.
(42) Duisenberg, A. J. Appl. Crystallogr. 1992, 25, 92−96.
(43) Duisenberg, A. J. M.; Kroon-Batenburg, L. M. J.; Schreurs, A. M.
M. J. Appl. Crystallogr. 2003, 36, 220−229.
(44) Sheldrick, G. M. SHELXL-97, Program for the Refinement of
Structures; University of Goettingen: Goettingen, Germany, 1997.
(45) Spek, A. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2009, 65,
148−155.
(46) (a) Farrugia, L. J. Appl. Crystallogr. 1997, 30, 565. (b) Burnett,
M. N.; Johnson, C. K. ORTEP-III; Oak Ridge National Laboratory:
Oak Ridge, TN, USA, 2000.
(47) Macrae, C. F.; Bruno, I. J.; Chisholm, J. A.; Edgington, P. R.;
McCabe, P.; Pidcock, E.; Rodriguez-Monge, L.; Taylor, R.; van de
Streek, J.; Wood, P. A. J. Appl. Crystallogr. 2008, 41, 466−470.
(19) (a) Ko, S.-B.; Park, H.-J.; Gong, S.; Wang, X.; Lu, Z.-H.; Wang,
S. Dalton Trans. 2015, 44, 8433−8443. (b) Tenne, M.; Metz, S.;
Munster, I.; Wagenblast, G.; Strassner, T. Organometallics 2013, 32,
̈
6257−6264.
(20) Tsai, J.-Y.; Elshenawy, Z. Thiazole and Oxozole Carbene Metal
Complexes as Phosphorescent OLED Materials. WO2012116242A1,
2012.
(21) (a) Green, R. A.; Pletcher, D.; Leach, S. G.; Brown, R. C. D. Org.
Lett. 2015, 17, 3290−3293. (b) Hovey, M. T.; Check, C. T.; Sipher, A.
F.; Scheidt, K. A. Angew. Chem., Int. Ed. 2014, 53, 9603−9607.
(22) Pesch, J.; Harms, K.; Bach, T. Eur. J. Org. Chem. 2004, 2004,
2025−2035.
(23) (a) Piel, I.; Pawelczyk, M. D.; Hirano, K.; Frohlich, R.; Glorius,
̈
F. Eur. J. Org. Chem. 2011, 2011, 5475−5484. (b) Schedler, M.;
Frohlich, R.; Daniliuc, C.-G.; Glorius, F. Eur. J. Org. Chem. 2012, 2012,
̈
4164−4171.
(24) (a) Kharasch, N.; Meyers, C. Y. The Chemistry of Organic Sulfur
Compounds; Wiley-Blackwell: Oxford, UK, 1966. (b) Vernin, G.
General Synthetic Methods for Thiazole and Thiazolium Salts. In
Chemistry of Heterocyclic Compounds: Thiazole and Its Derivatives;
Hoboken, NJ, USA, 1979; Vol. 19791, pp 165−335.
(25) (a) Djafri, A.; Roussel, C.; Sandstrom, J. J. Chem. Soc., Perkin
̈
Trans. 2 1985, 273−277. (b) Roussel, C.; Popescu, C. Chirality 1994,
L
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(48) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T., Jr.; Peralta, J. E.;
Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.;
Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.;
Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega,
N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.;
Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.;
Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.;
Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.;
Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.;
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09,
Rev. B 0.1; Gaussian, Inc.: Wallingford, CT, 2009.
(49) (a) Vosko, S. H.; Wilk, L.; Nusair, M. Can. J. Phys. 1980, 58,
1200−1211. (b) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B: Condens.
Matter Mater. Phys. 1988, 37, 785−789. (c) Miehlich, B.; Savin, A.;
Stoll, H.; Preuss, H. Chem. Phys. Lett. 1989, 157, 200−206. (d) Becke,
A. D. J. Chem. Phys. 1993, 98, 5648−5652. (e) Stephens, P. J.; Devlin,
F. J.; Chabalowski, C. F.; Frisch, M. J. J. Phys. Chem. 1994, 98, 11623−
11627.
(50) (a) Perdew, J. P. Phys. Rev. B: Condens. Matter Mater. Phys. 1986,
33, 8822−8824. (b) Perdew, J. P. Phys. Rev. B: Condens. Matter Mater.
Phys. 1986, 34, 7406. (c) Becke, A. D. Phys. Rev. A: At., Mol., Opt. Phys.
1988, 38, 3098−3100.
(51) (a) Ditchfield, R.; Hehre, W. J.; Pople, J. A. J. Chem. Phys. 1971,
54, 724−728. (b) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem.
Phys. 1972, 56, 2257−2261. (c) Hariharan, P. C.; Pople, J. A. Chem.
Phys. Lett. 1972, 16, 217−219. (d) Hariharan, P. C.; Pople, J. A. Theor.
Chim. Acta 1973, 28, 213−222. (e) Hariharan, P. C.; Pople, J. A. Mol.
Phys. 1974, 27, 209−214. (f) Rassolov, V. A.; Ratner, M. A.; Pople, J.
A.; Redfern, P. C.; Curtiss, L. A. J. Comput. Chem. 2001, 22, 976−984.
(g) Rassolov, V. A.; Pople, J. A.; Ratner, M. A.; Windus, T. L. J. Chem.
Phys. 1998, 109, 1223−1229.
(52) (a) Dunning, T. H. J. Chem. Phys. 1977, 66, 1382−1383.
(b) Binning, R. C.; Curtiss, L. A. J. Comput. Chem. 1990, 11, 1206−
1216.
(53) (a) Krishnan, R.; Binkley, J. S.; Seeger, R.; Pople, J. A. J. Chem.
Phys. 1980, 72, 650−654. (b) McLean, A. D.; Chandler, G. S. J. Chem.
Phys. 1980, 72, 5639−5648. (c) Clark, T.; Chandrasekhar, J.;
́
Spitznagel, G. W.; von Rague Schleyer, P. J. Comput. Chem. 1983, 4,
294−301. (d) Curtiss, L. A.; McGrath, M. P.; Blaudeau, J. P.; Davis, N.
E.; Binning, R. C.; Radom, L. J. Chem. Phys. 1995, 103, 6104−6113.
(e) Glukhovtsev, M. N.; Pross, A.; McGrath, M. P.; Radom, L. J. Chem.
Phys. 1995, 103, 1878−1885. (f) Blaudeau, J.-P.; McGrath, M. P.;
Curtiss, L. A.; Radom, L. J. Chem. Phys. 1997, 107, 5016−5021.
(54) (a) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299−310.
(b) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 270−283.
(c) Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284−298.
(55) Dennington, R., II; Keith, T.; Millam, J.; Eppinnett, K.; Hovell,
W. L.; Gilliland, R. GaussView, 3.09; Semichem Inc.: Shawnee Mission,
2003.
́
(56) Legault, C. Y. CYLview, 1.0b; Universite de Sherbrooke, 2009.
M
DOI: 10.1021/acs.organomet.5b00991
Organometallics XXXX, XXX, XXX−XXX