Unexpected metal-mediated oxidation of hydroxymethyl groups to coordinated carboxylate groups by bis-cyclometalated iridium(iii) centers

Article abstract of DOI:10.1039/b9nj00785g

Two different procedures of the 'click' reaction were applied to synthesize a library of 1-aryl- and 4-aryl-functionalized 1H-[1,2,3]triazoles as new ligands for phosphorescent iridium(iii) complexes. For three examples, single crystal X-ray analysis was

Full text of DOI:10.1039/b9nj00785g

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PAPER
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Unexpected metal-mediated oxidation of hydroxymethyl groups to
coordinated carboxylate groups by bis-cyclometalated iridium(III)
centersw
Beatrice Beyer,a Christoph Ulbricht,bc Andreas Winter,bc Martin D. Hager,ac
Richard Hoogenboom,b Nicole Herzer,b Stefan O. Baumann,d Guido Kickelbick,de
f
abc
¨
Helmar Gorls and Ulrich S. Schubert*
Received (in Montpellier, France) 23rd December 2009, Accepted 5th June 2010
DOI: 10.1039/b9nj00785g
Two different procedures of the ‘click’ reaction were applied to synthesize a library of 1-aryl- and
4-aryl-functionalized 1H-[1,2,3]triazoles as new ligands for phosphorescent iridium(III) complexes.
For three examples, single crystal X-ray analysis was carried out and the structural properties
were discussed. The reactive m-dihydroxy-bridged iridium(III) precursor complex [(ppy)2Ir-m-(OH)]2
(ppy = 2-phenylpyridinato) was prepared for the complexation of the herein described ligands.
During these complexation studies, an unexpected metal-assisted oxidation pathway was observed
for the hydroxymethyl-substituted 1-aryl-1H-[1,2,3]triazoles 2d–f leading selectively to a
[carboxylate-N3,O]-coordination of the ligands to the iridium(III) centers.
ligands.1,2a Generally, emission originates from a triplet
Introduction
state with metal-to-ligand charge-transfer (MLCT) and/or
ligand-centered (LC) character. Furthermore, internal quantum
efficiencies close to 100% can be achieved in electroluminescent
devices doped with these phosphorescent emitters.9,10
Due to their rich photophysical and electrochemical proper-
ties, cyclometalated complexes of heavy transition metal ions
have gained much interest in modern materials research. In
particular, the development of high-performance materials is
of utmost importance for the fabrication of efficient organic
light-emitting diodes (OLEDs).1,2 A wide range of materials,
including organic polymers,3 small organic molecules4 and
coordination compounds,2,5 have been processed successfully
into devices. Besides the transition metal ions with d8 electron
configuration (i.e. PtII, PdII and AuIII),6–8 in particular d6
species have recently experienced increasing attention.1,2 In
contrast to complexes based on other heavy transition metal
ions (e.g., RuII, OsII or RhIII), cyclometalated iridium(III)
complexes exhibit intense phosphorescence even at room
temperature and combine advantageous characteristics such
as short phosphorescence lifetimes in the ms regime due to
strong spin–orbit coupling, as well as emission color tunability
from blue to red depending on the nature of the coordinated
The coordination chemistry of IrIII allows for the selective
synthesis of tris- and bis-cyclometalated complexes.11 The
m-dichloro-bridged dimer complexes (i.e. [Ir(C^N)2-m-Cl]2),
conveniently prepared from a reaction of the respective cyclo-
metalating ligand (HC^N) and iridium(III) chloride hydrate,
play a central role in the chemistry of cyclometalated IrIII
complexes (Scheme 1).1,2a,b In general, the chloro-bridge of
such dimer precursor complexes can be easily split by coordi-
nating solvents (e.g., pyridine, DMSO, CH3CN)12 as well
as chelating ligands leading to neutral (e.g., b-diketonates
or picolinates as ligands) or charged bis-cyclometalated
complexes (e.g., 2,20-bipyridines or 1,10-phenanthrolines as
ligands) by preserving the precursor inherent trans-N,N
configuration of the C^N ligands (path a in Scheme 1).1,2,13
a Laboratory of Organic and Macromolecular Chemistry,
Friedrich-Schiller-University Jena, Humboldtstr. 10, 07743 Jena,
Germany. E-mail: ulrich.schubert@uni-jena.de;
Fax: +49 3641 948202; Tel: +49 3641 948200
b Laboratory of Macromolecular Chemistry and Nanoscience,
Eindhoven University of Technology, P.O. Box 513,
5600 MB Eindhoven, The Netherlands
c Dutch Polymer Institute (DPI), P.O. Box 902,
5600 AZ Eindhoven, The Netherlands
d Institute of Materials Chemistry, Vienna University of Technology,
Getreidemarkt 9/165, 1060 Vienna, Austria
e Inorganic Solid State Chemistry, Saarland University,
Am Markt Zeile 3, 66125 Saarbrucken, Germany
¨
f Laboratory of Inorganic and Analytic Chemistry,
Friedrich-Schiller-University Jena, Lessingstr. 8, 07743 Jena,
Germany
w CCDC 726545–726547 (2d–g). For crystallographic data in CIF or
other electronic format see DOI: 10.1039/b9nj00785g.
Scheme 1 Schematic representation of the synthetic strategies utilized
for the synthesis of cyclometallated iridium(III) complexes.2a
ꢀc
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The coordination of a third cyclometalating ligand to the
m-dichloro-bridged dimer provides access to tris-cyclometalated
IrIII complexes (paths b/c, Scheme 1). With cautious control of
the reaction conditions, the kinetically-preferred meridional
(mer) or the thermodynamically-favored facial (fac) isomers are
accessible, homoleptic as well as heteroleptic ones, with high
selectivity.2a Also, the direct route towards homoleptic tris-
cyclometalated species, fac-Ir(C^N)3, starting from the Ir(acac)3
precursor (acac = acetoacetonate) or IrCl3 ꢁ 3H2O is a common
approach for phenylpyridine (Hppy) and its derivatives (path d,
Scheme 1).2,14 However, this synthesis usually requires harsh
reaction conditions, for example refluxing glycerol or excess of
ligand.15,16 The required large excess of ligand material and the
formation of the m-dichloro-bridged dimer as by-product remain
as major drawbacks of this approach.17 The kinetically favored
mer-isomers can be obtained by performing the reactions at
lower temperatures (e.g., in glycerol at 120 to 150 1C) inhibiting
the formation of the fac-isomers. Generally, the electro-optical
properties of these two configurational isomers differ signifi-
cantly. The fac-isomers feature an order of magnitude longer
emission lifetimes and higher quantum efficiencies compared
to mer-isomers at room temperature making them promising
candidates as emitters in OLEDs and further applications.10,15
Besides the well-established m-dichloro-bridged dimer
complexes, also their m-dihydroxy-bridged counterparts
(i.e. [Ir(C^N)2-m-(OH)]2) have been utilized in particular for
the synthesis of meridional tris-cyclometalated complexes
under comparably mild conditions.10
The recent developments in the field of phosphorescent IrIII
complexes with respect to color tuning have been reviewed
and an enormous structural diversity of cyclometalating ligands
and tris-cyclometalated IrIII complexes is known in the litera-
ture.2a Among others, 1-phenyl-pyrazoles18 and 1-phenyl-1H-
[1,2,4]triazoles19 have recently been introduced as new types of
cyclometalating ligands. Furthermore, 1H-[1,2,3]triazoles—
synthesized by the Huisgen 1,3-dipolar cycloaddition reaction
(the so-called ‘click’ reaction)20—in the coordination sphere of
heavy transition metal ions showed already the promising
potential for serving as a ligand.21–27 And indeed, it was shown
recently that 1-phenyl- and 4-phenyl-1H-[1,2,3]triazoles can be
introduced as new cyclometalating ligands in the synthesis of
various types of charged and neutral bis-cyclometalated IrIII
complexes.28
Scheme 2 Schematic representation of the synthesis of 4-aryl-1H-
[1,2,3]triazoles 1a–d and 4-substituted 1H-[1,2,3]triazoles 1e–g.
2. As depicted in Scheme 2, a variety of alkyl bromides were
converted in situ into the corresponding azides,29 which were
reacted with ethynylbenzene to yield the 4-aryl-substituted
1H-[1,2,3]-triazoles (1) in up to 78% yield (Table 1).21,23,28
A
significant decrease in the isolated yield was observed for the
functionalized derivatives 1b/c (39% and 13%, respectively)
compared to 1a (76%) and the ‘double clicked’ derivative 1d
(63%). Since the generation of the azides from the corres-
ponding bromides was carried out under the same reaction
conditions for all examples, the ‘click’ reaction was apparently
not equally successful. In particular, the low yield for the
derivative 1c was attributed to a deactivation of the in situ
generated copper(I) catalyst by the carboxylic group. It is
noteworthy in this context that no product could be isolated
for the ‘click’ reaction when the ethynylbenzene was replaced
by propargylic acid (entry 1e in Table 1).30 However, the
general protocol could be applied to ‘click’ propargylic
acid ester and propargylic alcohol31 obtaining the ester- and
alcohol-substituted derivatives 1f (47%) and 1g (78%),
respectively.
According to the literature, aromatic azides can be generated
in situ from their respective boronic acids32 or bromides.33 The
latter one was chosen for a two-step one-pot procedure
adapting a protocol introduced by Anderson et al. (Scheme 3).
Both steps, the formation of the azide and the subsequent
‘click’ reaction, are CuI-catalyzed. The progress of the sub-
stitution of bromide by azide was accompanied by a change in
color from blue over green and brown to pale yellow. The
course of the reaction was additionally monitored by GC-MS
measurements. To the best of our knowledge, the mechanism
for this substitution reaction has not been fully clarified.
However, it has been shown that the blue color originates
from an intermediate formed by the copper(I) catalyst, the
bidentate co-ligand (N,N-dimethylethylenediamine, DMEDA)
and the azide anion. Such chelating amino-coligands are known
to accelerate significantly the substitution of bromide.33
For the subsequent azide–alkyne coupling, no additional
copper(I) catalyst was required. Apparently, the CuI was not
fully consumed or oxidized in the first step and, furthermore,
the additional chelating DMEDA ligand did not disturb the
‘click’ reaction. This observation is in agreement with examples
known from the literature, where nitrogen-containing bases
were also used to accelerate the ‘click’ reaction.34
Continuing this prior work, the synthesis of a variety of 4-aryl-
and 1-aryl-1H-[1,2,3]triazole derivatives as well as their ability to
coordinate reactive dimeric precursor complexes [Ir(ppy)2-m-X]2
(X = Cl, OH)—aiming for heteroleptic tris-cyclometalated IrIII
complexes—is described. The unexpected metal-mediated oxida-
tion pathway for the m-hydroxy-bridged dimer complex and
hydroxymethyl-substituted triazole-derivatives yielding neutral
heteroleptic bis-cyclometalated IrIII complexes with 1H-[1,2,3]-
triazole-2-carboxylates as ligands is discussed.
Results and discussion
Synthesis and characterization of phenyl-1H-[1,2,3]-triazoles
The isolated yields of the 1-aryl-substituted derivatives 2
were moderate to good and comparable to those obtained for
their 4-aryl-counterparts 1 (Table 1). The low yield for 2b
Two variants of the ‘click’ reaction were used for the synthesis
of 4-aryl-1H-[1,2,3]triazoles 1a–d and 1-aryl-1H-[1,2,3]triazoles
ꢀc
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Table 1 Synthesis of substituted 1H-[1,2,3]triazoles 1 and 2
Compound Structure
Method Yielda (%)
1a
A
A
A
76
39
13
Scheme 3 Schematic representation of the synthesis of 1-aryl-1H-
[1,2,3]triazoles 2.
1b
1c
(21%) can be explained by the low solubility of the reactants in
the polar protic solvent mixture.
All 1H-[1,2,3]triazole derivatives 1 and 2 were fully charac-
terized by NMR and UV/vis spectroscopy, MALDI-TOF
mass spectrometry as well as elemental analysis. For all
compounds described herein the expected high selectivity of
the ‘click’ reaction towards the 1,4-isomer was observed (the
1d
A
63
1
1,5-isomer could not be detected by H NMR spectroscopy).
The detailed characterization of the isomeric derivatives 1a
and 2a and the applicability as cyclometalating ligands in
phosphorescent iridium(III) complexes is reported elsewhere.28
b
1e
1f
A
A
—
Single-crystal X-ray diffraction analysis
Single crystals of the 1,4-diaryl-substituted 1H-[1,2,3]triazole
2d and the hydroxy-functionalized 1-aryl-1H-[1,2,3]triazoles
2e/g were obtained by slow crystallization from concentrated
CH2Cl2/n-pentane mixtures. Geometric information (atom
distances and bond angles) of the compounds 2d/e/g and their
crystallographic data are summarized in Tables 2 and 3.w The
numbering of the atoms of the common structural motive is
depicted in Fig. 1–3.
47
1g
2a
2b
A
B
B
78
67
21
All structures show the typical bond distances and angles of
substituted triazoles.32,35 Structure 2d (Fig. 1) reveals a triazole
ring which is nearly co-planar to the 3,5-dimethyl-substituted
aryl ring displaying a tilting angle of 6.17(7)1. In contrast, the
plane through the unsubstituted phenyl ring reveals a tilting
angle to the plane through the triazole ring of 28.53(9)1. The
crystal packing shows no interactions between the molecules,
such as p–p-stacking or hydrogen bonds. Here, a better optimal
space filling seems to compensate a loss in conjugation.
As shown in Fig. 2, structure 2e consists of two co-planar
aryl ring systems (C(6)–C(11) and C(14)–C(19), tilting angle:
10.12(9)1). The tilting angle between the plane through the
triazole and the directly connected aryl ring is 25.29(7)1.
The three-dimensional packing of the molecular structures in
the crystal reveals hydrogen bonds between the O(13)–H(13)
groups and neighboring N(3) atoms with a N–H distance of
2.04(2) A.
2c
2d
B
B
63
67
2e
2f
B
B
59
61
The X-ray analysis of 2g (Fig. 3) reveals a similar dihedral
angle (23.7(2)1) between the central triazole and the dimethyl-
benzene ring as for 2e. However, this is in contrast to the solid
state structure of the related compound 2d displaying signifi-
cantly smaller angles. The crystal packing of 2g displays two
kinds of hydrogen bonds. Similar to 2e, hydrogen bonds were
observed between the O(15)–H(15) groups and neighboring
N(3) atoms with a N–H distance of 1.93(3) A. In addition, a
weak hydrogen bond between the O(15) of the OH-group and
the C(5)–H(5) bond of the neighboring aryl ring with a O–H
distance of 2.24(3) A was found.
2g
B
70
a
b
Isolated yield (see Experimental section for details). No product
could be isolated.
ꢀc
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Table 2 Comparison of typical crystal data of compounds 2d/e/g
2d
2e
2g
Distances/A
N(1)–N(2)
N(2)–N(3)
N(1)–C(5)
N(3)–C(4)
C(4)–C(5)
C(5)–H
C(4)–C(12/14)
C(12/14)–O
O–H
N(1)–C(6)
C(6)–C(7)
C(6)–C(11)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
C(7)–H
C(11)–H
1.347(2)
1.304(2)
1.349(2)
1.356(2)
1.358(2)
0.930(0)
1.473(2)
—
1.349(1)
1.310(2)
1.352(2)
1.354(2)
1.363(2)
0.930(0)
1.495(2)
1.412(2)
0.820(0)
1.424(2)
1.380(2)
1.384(2)
1.384(2)
1.394(2)
1.393(2)
1.379(2)
0.930(0)
0.930(0)
1.350(2)
1.315(2)
1.356(2)
1.367(3)
1.364(3)
0.950(2)
1.491(3)
1.424(3)
0.870(3)
1.435(2)
1.390(3)
1.382(3)
1.390(3)
1.391(3)
1.394(3)
1.391(3)
0.970(2)
0.950(2)
—
1.429(2)
1.383(2)
1.391(2)
1.391(2)
1.379(2)
1.387(3)
1.391(2)
0.930(0)
0.930(0)
Angles/1
N(1)–N(2)–N(3)
N(2)–N(3)–C(4)
N(3)–C(4)–C(5)
C(4)–C(5)–N(1)
C(5)–N(1)–N(2)
C(6)–N(1)–N(2)
C(6)–N(1)–C(5)
N(1)–C(6)–C(11)
N(1)–C(6)–C(7)
N(3)–C(4)–C(12/14)
C(5)–C(4)–C(12/14)
C(4)–C(12/14)–O
C(4)–C(14)–C(15)
C(4)–C(14)–C(19)
C(6)–C(7)–C(8)
C(6)–C(11)–C(10)
C(7)–C(6)–C(11)
C(7)–C(8)–C(9)
C(8)–C(9)–C(10)
C(9)–C(10)–C(11)
N(1)–C(5)–H
C(4)–C(5)–H
C(12/14)–O–H
107.64(13)
109.18(14)
107.77(13)
105.78(12)
109.63(13)
120.19(12)
130.16(12)
118.83(14)
120.45(12)
121.72(14)
130.50(13)
—
120.14(15)
121.19(16)
120.01(14)
119.63(15)
120.72(15)
118.79(15)
122.05(16)
118.78(14)
127.10(00)
127.10(00)
—
106.67(10)
109.82(10)
107.87(10)
105.17(11)
110.45(10)
119.64(10)
129.84(10)
119.61(11)
120.84(11)
122.15(11)
129.81(13)
112.21(11)
—
106.58(15)
109.80(16)
107.63(18)
105.34(17)
110.65(15)
120.51(15)
128.82(17)
119.64(17)
118.45(18)
122.44(17)
129.87(18)
112.15(17)
—
Fig. 1 Molecular structure (top) and packing diagram (bottom)
obtained from single-crystal X-ray diffraction analysis of 2d. The
ellipsoids represent a probability of 40%.
—
—
119.70(11)
119.88(11)
119.55(11)
122.31(11)
116.29(11)
122.27(11)
127.40(00)
127.40(00)
109.50(00)
119.33(19)
119.44(19)
121.79(19)
118.68(19)
122.11(19)
118.61(19)
121.30(14)
133.30(14)
106.90(19)
Table 3 Summary of the crystallographic data for 2d/e/g
2d
2e
2g
Empirical formula
M/g molꢂ1
T/K
C16H15N3
249.31
296(2)
C15H13N3O C11N13N3O
203.24
183(2)
251.28
300
Crystal system
Space group
a/A
b/A
c/A
a/1
b/1
orthorhombic orthorhombic monoclinic
Pna21
10.983(2)
10.056(2)
12.375(3)
90
Pbca
P21/c
7.4938(4)
8.0177(3)
9.0879(4)
9.1648(4)
29.4080(14) 17.8009(11)
90
90
90
Fig. 2 Molecular structure (top) and packing diagram (bottom)
obtained from single-crystal X-ray diffraction analysis of 2e. The
ellipsoids represent a probability of 40%.
90
93.744(3)
90
90
90
g/1
V/A3
1366.7(5)
4
2449.36(19) 1067.25(10)
8
l-Dihydroxy bridged dimeric iridium(III) precursor complex
Z
4
r/g cmꢂ3
Reflections
Unique reflections
1.212
19525
1953
1.363
19846
3038
1.265
7341
3038
As pointed out previously, general routes leading to homo-
leptic as well as heteroleptic tris-cyclometalated IrIII complexes
have been reported. A promising approach towards the selective
synthesis of heteroleptic tris-cyclometalated IrIII complexes
was recently introduced by McGee and Mann.10 Utilizing a
more reactive dimeric precursor complex, the formation of the
mer-isomer under mild conditions could be achieved. In order
Final R indices [I 4 2s(I)], 0.0351,
R1, wR2 0.1032
R indices (all data), R1, wR2 0.0515,
0.0461,
0.1252
0.0560,
0.1374
726546
0.0546,
0.1324
0.0964,
0.1537
726547
0.0911
726545
CCDC deposition
number1w
ꢀc
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Fig. 4 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of the precursor
complexes [(ppy)2Ir-m-Cl]2 (bottom) and [(ppy)2Ir-m-(OH)]2 (3, top).
investigated by mass spectrometric techniques. The synthesis
1
and H NMR spectrum of 3 was reported previously.10,12b,36
However, the chemical shift we found for the protons of the
m-hydroxy-bridge (d = ꢂ1.45 ppm, integral: 2 H) is in contra-
diction to two of these references (d = 3.77 ppm),10,12b but
similar to the patent (d = ꢂ1.00 ppm).36 Apparently, due to
strong shielding-effects, the signal originating from the hydroxy-
bridge protons is remarkably shifted to very high field. In
addition, the good agreement of the found elemental composi-
tion with the theoretical values supports the formation of the
desired hydroxy-bridged precursor complex.37 The previously
described preparation of the dimeric precursor with a chemical
shift of d = 3.77 ppm was carried out in methanol starting from
bis-cyclometalated IrIII solvato complexes (i.e. [(ppy)2Ir(L)2]+;
L = H2O and CH3CN, respectively).10,12b Therefore, the
formation of a m-methoxy-bridged precursor rather than a
m-hydroxyl-bridged complex might be speculated under these
reaction conditions.
Fig. 3 Molecular structure (top) and packing diagram (bottom)
obtained from single-crystal X-ray diffraction analysis of 2g. The
ellipsoids represent a probability of 40%.
to investigate if the herein described phenyl-1H-[1,2,3]triazole
derivatives 1 and 2 can be used as cyclometalating ligands
in heteroleptic tris-cyclometalated IrIII complexes, a similar
approach was followed.
The synthesis of 3 was carried out adapting a patent
description (Scheme 4).36 In analogy to this, 2-phenyl-pyridine
as cyclometalating ligand was reacted with IrCl3 ꢁ xH2O in a
refluxing ethoxyethanol/water mixture resulting in the in situ
formation of the m-dichloro-bridged dimer complex [Ir(ppy)2-
m-Cl]2 (step a). The chloro-bridge was subsequently opened
under strong basic conditions (step b: NaOH, water, reflux). 3
was obtained as orange-brown solid in good yield (78%) after
further treatment with aq. NaOH in dichloromethane (step c).
The structure of 3 was confirmed by NMR spectroscopy
(the 1H NMR spectrum is depicted in Fig. 4) as well as by
elemental analysis. Due to the instability of the m-hydroxy-
bridge under the measurement conditions, 3 could not yet be
Phenyl-1H-[1,2,3]-triazoles as potential cyclometalating ligands
It was shown recently that phenyl-1H-[1,2,3]triazoles (i.e. 1a
and 2a) can be used as cyclometalating ligands for the synthesis
of bis-cyclometalated heteroleptic IrIII complexes, including
cationic (e.g., 2,20-bipyridine as ancillary ligand) as well as
neutral ones (e.g., acetylacetone or picolinate as ancillary
ligand).28 The m-dihydroxy-bridged IrIII precursor complex 3
was treated with the triazole derivatives 1 and 2 in order to
obtain the neutral heteroleptic tris-cyclometalated IrIII
complexes (4).38 Following the protocol described by McGee
and Mann,10 the reactions were carried out with stoichio-
metric amounts of the triazole compound (1 or 2) under inert
conditions in refluxing chloroform (Scheme 5).
Surprisingly, only the hydroxymethyl-functionalized 1-phenyl-
1H-[1,2,3]triazole derivatives (R2 = CH2OH, 2e–g) resulted in
the formation of a new and emitting species as monitored by
thin layer chromatography (TLC) using an UV lamp.39 After
full consumption of the triazole ligand, the formed complexes
were isolated, purified by column chromatography and char-
acterized by 1H NMR spectroscopy, mass spectrometry
and elemental analysis. However, not the anticipated tris-
cyclometalated heteroleptic IrIII complexes (4) were obtained.
Scheme 4 Schematic representation of the synthesis of the dimeric
m-hydroxy-bridged IrIII precursor 3.
ꢀc
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Scheme 5 Schematic representation of the coordination reactions performed in this study using [Ir(ppy)2-m-OH]2.
As confirmed by NMR spectroscopy, an unexpected coordi-
nation of the ligands 2e–g via a carboxylic group formed by
oxidation of the hydroxymethyl-function and the N3-atom of
the triazole ring occurred (Scheme 5). In fact, the coordination
of such 1H-[1,2,3]triazole-2-carboxylates to transition metal
the methylene-group were observed by 1H NMR and 13C
NMR spectroscopy. Instead, the low-field signal at 168 ppm
in the 13C NMR spectrum indicated the presence of a carboxy-
group and, therefore, gave further evidence that the
hydroxymethyl-group was oxidized to a carboxylic group
under these reaction conditions.
1
centers has not been reported in the literature before. The H
NMR spectrum of the methoxy-functionalized complex 5b is
depicted in Fig. 5. The characteristic signals for the
ppy-ligands (e.g., d = 6.00–6.50 ppm) and the triazole moiety
(d = 8.40 ppm) can be assigned. Additionally, the distinct
AA0XX0-system of the disubstituted phenyl ring can be
unambiguously verified proving that the expected cyclo-
metalation of 2f did not occur. Furthermore, no signals of
For all complexes of the series (5a–c), high resolution
electrospray ionization mass spectrometry (HR-ESI MS) was
carried out to support the postulated metal-mediated oxida-
tion sequence. All ESI mass spectra showed the characteristic
[Ir(ppy)2]+ fragment in addition to peaks that can be assigned
to [M + Na]+, [M + H]+ and [M + Ir(ppy)2]+ adducts,
respectively.
In a control experiment, (pyridin-2-yl)methanol40 was
coordinated to the IrIII precursor complex 3 applying the same
reaction conditions. Since the coordination pattern in 5 is
analogous to the one of a picolinate (pic) complex, the
previously made assumptions are supported. Apparently the
coordination of (pyridin-2-yl)methanol by 3 was followed by a
metal-supported oxidation of the hydroxymethyl-function to a
carboxylic group, which coordinated to the metal centre. This
led to the formation of 6 as a final species. Independently,
[Ir(ppy)2(pic)] was synthesized according to the literature from
[Ir(ppy)2-m-Cl]2 and picolinic acid under basic conditions
(i.e. Na2CO3 in CH2Cl2).41 Both compounds show identical
1H NMR spectra (Fig. 5). Furthermore, the measured
MALDI-TOF mass spectrum of 6 was in good agreement
with the calculated one.
This coordination study clearly supports the proposed
metal-mediated oxidation of the hydroxymethyl-group to the
corresponding carboxylic acid under the mentioned reaction
conditions. However, the isolated yield (Table 4) of this
sequence of oxidation and coordination was significantly
lower in comparison to the direct coordination of picolinic
Fig. 5 1H NMR spectra (400 MHz, 298 K, aromatic region) of 5b
(CDCl3, top),
bottom).
6 (CD2Cl2, middle) and [Ir(ppy)2(pic)] (CD2Cl2,
ꢀc
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Table
sequence
4
Synthesis of complexes via the oxidation-coordination
4-phenyl-1H-[1,2,3]triazoles (1 and 2). As reactive species, the
m-dihydroxy-bridged IrIII precursor complex [Ir(ppy)2-m-(OH)]2
(3) was prepared and fully characterized for the first time. The
reaction of 3 with hydroxymethyl-functionalized triazoles
followed an unexpected metal-mediated oxidation pathway
Complex
Ligand
Yielda (%)
5a
5b
5c
6
2e
2f
2g
27
39
21
30
yielding
a
new type of neutral bis-cyclometalated IrIII
(Pyridin-2-yl)methanol
1g
complexes with 1H-[1,2,3]triazole-2-carboxylates as ancillary
ligands which were not directly accessible via common
CuI-catalyzed ‘click’ chemistry approaches.
b
7
—
a
b
Isolated yield (see Experimental section for details). No product
could be isolated.
Experimental
acid to the bis-cyclometalated IrIII center. Consistently, low
yields were also observed for the triazole-containing com-
plexes. In addition, complexes 5a–c bearing 1H-[1,2,3]tria-
zole-2-carboxylate ligands were found to be relatively
unstable—partial decomposition in solution was observed
upon purification by column chromatography.42 The reaction
of 4-alkyl-triazole 1g gave an unseparable mixture of com-
plexes; the formation of the complex 7 could not be detected
by NMR spectroscopy and mass spectrometry.
Materials
Solvents were purchased from Biosolve. Chemicals of reagent
grade were obtained from commercial suppliers and were used
as received unless otherwise specified. Column chromato-
graphy was carried out on standardized aluminium oxide 90
(0.063–0.200 mm) or silica gel 60 (0.040–0.063 mm) purchased
from Merck. Thin layer chromatography (TLC) was
performed on Merck 60 F254 precoated silica gel and
aluminium oxide sheets. (Pyridin-2-yl)methanol40 and
[(ppy)2Ir(pic)]41 were synthesized according to the literature.
The mechanistic pathway leading to the formation of
complexes 5 and 6 is not yet fully understood. Nonetheless,
all complexation reactions were carried out under inert condi-
tions and, thus, oxidation by air can be excluded. Since the
utilizing of the m-dichloro-bridged dimer complex (i.e. [Ir(ppy)2-
m-Cl]2) instead of 3 did not lead to the formation of complexes 5
and 6, respectively, the m-hydroxy-bridge seems to play an
important role in the herein described reaction. The catalytic
activity of IrIII complexes with respect to various oxidation
processes, e.g., the conversion of primary and secondary
alcohols to aldehydes and ketones, respectively, is well-known
from the literature.43 In most cases, those oxidations could be
observed in reducing solvents (e.g., acetone) to regenerate the
catalytically active species. Also the oxidation of aldehydes to
the corresponding carboxylic acids in the presence of oxygen
under acidic conditions was reported.43d In the present case, the
reaction was carried out in chlorinated solvents under inert
conditions and, therefore, deriving an explanation of the
mechanism does not appear straightforward. However, we
can summarize that the coordination of the substrate (i.e. the
ligand) to the IrIII center via a N-atom is essential (a related
template driven oxidation of CH2-groups was already reported
for NiII species, see ref. 44). Control experiments with 3 and
benzylic alcohol or benzaldehyde did not indicate the formation
of benzaldehyde or benzoic acid, respectively, as confirmed by
GC-MS measurements. This allows the conclusion that a
coordination of the alcohol is required for the oxidation. The
comparatively low yield of the reaction of 3 and 2e–g might
indicate that another IrIII species might be consumed irrever-
sibly during the process. Detailed investigations to understand
the observed sequence of metal-mediated oxidation and
coordination towards complexes 5—supported by online
NMR and IR spectroscopy—are currently ongoing.
Instrumentation
For the microwave-assisted synthesis a single mode Biotage
Initiator 8 was used. The reactions were performed under
temperature control, the pre-stirring time was 10 s, and the
stirring rate was set to 600 rpm. The electromagnetic field had
a frequency of 2.45 GHz. 1D- (1H and 13C) and 2D-
(1H-1H gCOSY) NMR spectra were recorded on a Varian
Mercury 400 MHz instrument at 298 K. Chemical shifts are
reported in parts per million (ppm) high field to the residual
solvent peaks. Coupling constants are reported in Hertz (Hz).
UV/vis absorption spectra were recorded at sample concen-
trations of 10ꢂ5 to 10ꢂ6 mol Lꢂ1on a Perkin-Elmer Lambda
45 UV/VIS Spectrometer (1 cm cuvettes). A GC-MS-QP5000
instrument was used to monitor the reaction progress and for
electron-ionization mass spectrometry (EI-MS). For standard
measurements the injection and the interface temperature were
set to 300 and 250 1C, respectively. Matrix-assisted laser
desorption-ionization time-of-flight (MALDI-TOF) mass
spectrometry was performed on a Voyager-DE PRO Bio-
spectrometry Workstation (Applied Biosystems) time-of-flight
mass spectrometer, using dithranol as matrix. High resolution
electrospray ionization (HiResESI) mass spectrometry was
carried out on a Finnigan MAT 95XL machine. Elemental
analyses were performed on a EuroVector EuroEA 3000
elemental analyzer (Hekatech) for CHNS-O.
X-Ray crystallography analysis
Selected crystals of 2d and 2e were mounted on a Bruker-AXS
APEX diffractometer with a CCD area detector. For 2g, the
intensity data were collected on a Nonius-Kappa CCD
diffractometer. Graphite-monochromated Mo-Ka radiation
(0.71073 A) was used for all measurements. The data were
corrected for polarization and Lorentz effects, and an
empirical absorption correction (SADABS)45 was applied for
2d and 2e.46 The cell dimensions were refined with all unique
Conclusions
Different CuI-catalyzed ‘click’ chemistry procedures were used
to synthesize a library of functionalized 1-phenyl- and
ꢀc
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reflections. The structures were solved by direct methods
(SHELXS-97).47 Refinement was carried out with the
full-matrix least-squares method based on F2 (SHELXL-97)48
with anisotropic thermal parameters for all non-hydrogen
atoms. The hydrogen atoms of 2g except for the methyl-
groups and the hydrogen of the hydroxy-group of 2e were
located by difference Fourier synthesis and refined isotro-
pically. All other hydrogen atoms were inserted in the calculated
positions and refined riding with the corresponding atom.
MHz; CD2Cl2; Me4Si) 7.84 (d, J = 8.4 Hz, 2 H, aryl-H), 7.80
(s, 1 H, triazole-H), 7.44 (mc, 2 H, aryl-H), 7.34 (t, J = 7.4 Hz,
1 H, aryl-H), 4.39 (t, J = 7.2 Hz, 2 H, alkyl-H), 3.58 (mc, 2 H,
alkyl-H), 1.95 (mc, 2 H, alkyl-H), 1.53 (mc, 2 H, alkyl-H),
1.45–1.26 (m, 14 H, alkyl-H); dC (100 MHz; CD2Cl2; Me4Si)
147.3, 131.0, 128.8, 127.9, 125.5, 119.5, 62.8, 50.4, 32.8, 30.3,
29.5, 29.4, 29.3, 28.9, 26.4, 25.7; m/z (MALDI-TOF MS,
dithranol) 316.06 (100%, [M + H]+); lmax (CH2Cl2)/nm
248 (e/dm3 molꢂ1 cmꢂ1 18 200).
Method A: general procedure for the synthesis of 4-aryl-1H-
11-(4-Phenyl-1H-[1,2,3]triazol-1-yl)undecanoic acid (1c)
[1,2,3]triazoles (1)
According to the general procedure, 1c was isolated as a white
powder (62 mg, 13%). Deviating from the general protocol,
CuI (39 mg, 0.20 mmol) and sodium L-ascorbate (20 mg,
0.10 mmol) were used as catalytic system. The crude product
was dissolved in CH2Cl2 (200 mL) and extracted with water
(100 mL) containing hydroxyethylethylenediaminetriacetic
acid (HEDTA, 4 mL) for 14 h. Afterwards the organic phase
was washed with water (3 ꢁ 60 mL). dH (400 MHz; CD2Cl2;
Me4Si) 7.83 (d, J = 7.2 Hz, 2 H, aryl-H), 7.81 (s, 1 H, triazole-H),
7.44 (mc, 2 H, aryl-H), 7.34 (t, J = 7.4 Hz, 1 H, aryl-H), 4.39
(t, J = 7.2 Hz, 2 H, alkyl-H), 2.37 (mc, 2 H, alkyl-H), 1.94
(mc, 2 H, alkyl-H), 1.63 (mc, 2 H, alkyl-H), 1.36–1.29 (m, 14 H,
alkyl-H); dC (100 MHz; CD2Cl2; Me4Si) 173.8, 147.3, 130.9,
128.8, 127.9, 125.5, 119.6, 50.4, 30.2, 29.2, 29.1, 28.9, 28.9,
26.4; m/z (MALDI-TOF MS, dithranol) 330.51 (100%,
[M + H]+); lmax (CH2Cl2)/nm 248 (e/dm3 molꢂ1 cmꢂ1 12 900).
A suspension of an alkylbromide (5 mmol) and NaN3
(7.5 mmol) in ethanol/water (7 : 3 ratio, 15 mL) was heated
under microwave irradiation for 1 h at 125 1C (absorption
level of the microwave on high).z Subsequently, solutions
of sodium L-ascorbate (1.5 mmol) and CuSO4 ꢁ 5H2O
(0.4 mmol) were added. After the dropwise addition of the
acetylene compound (7.5 mmol), a color change of the reac-
tion mixture to bright yellow was observed and stirring at
room temperature was continued for 15 h. Then, water
(200 mL) was added to precipitate the product. After filtra-
tion, washing with water and drying, the residue was stirred in
CH2Cl2 (200 mL) for one hour and filtered. The organic
solution was washed with water (3 ꢁ 50 mL) and dried over
MgSO4. If necessary, residues of the copper catalyst were
removed by a short gel filtration (silica gel, CH2Cl2 or
CH2Cl2/methanol as eluent). The concentrated CH2Cl2 phase
was dropped into n-pentane (100–150 mL) to yield the desired
4-aryl-1H-[1,2,3]-triazole (1) as precipitate.
(1,3-Bis-1-decyl-1H-[1,2,3]triazol-4-yl)-benzene (1d)
According to the general procedure, 1d was isolated as a white
powder (623 mg, 63%). Deviating from the general protocol,
the reaction was carried out at 65 1C. Ethyl acetate was used as
solvent in the purification step. (Found: C, 73.35; H, 9.97; N,
17.19%. C30H48N6 requires C, 73.13; H, 9.82; N, 17.06%); dH
(400 MHz; CD2Cl2; Me4Si) 8.31 (s, 1 H, aryl-H), 7.90 (s, 2 H,
triazole-H), 7.82 (d, J = 8.0 Hz, 2 H, aryl-H), 7.51 (t, J =
7.8 Hz, 1 H, aryl-H), 4.41 (t, J = 7.2 Hz, 4 H, alkyl-H), 2.02
(mc, 4 H, alkyl-H), 1.40–1.20 (m, 28 H, alkyl-H), 0.89 (m, 6 H,
alkyl-H); dC (100 MHz; CD2Cl2; Me4Si) 147.0, 131.5, 129.3,
125.0, 122.5, 119.8, 50.4, 31.8, 30.3, 29.5, 29.4, 29.2, 29.0, 26.5,
22.6, 13.8; m/z (MALDI-TOF, dithranol) 493.4 (100%,
[M + H]+); lmax (CH2Cl2)/nm = 342 (e/dm3 molꢂ1 cmꢂ1 35 400).
1-Decyl-4-phenyl-1H-[1,2,3]triazole (1a)
According to the general protocol, 1a was obtained as color-
less needles (652 mg, 76%). (Found: C, 75.69; H, 9.83; N,
14.54%. C18H27N3 requires: C, 75.74; H, 9.83; N, 14.54%); dH
(400 MHz; CD2Cl2; Me4Si) 7.84 (d, J = 7.2 Hz, 2 H, aryl-H),
7.80 (s, 1 H, triazole-H), 7.44 (mc, 2 H, aryl-H), 7.34 (t, J =
7.4 Hz, 1 H, aryl-H), 4.39 (t, J = 7.2 Hz, 2 H, alkyl-H), 1.95
(mc, 2 H, alkyl-H), 1.37–1.29 (m, 14 H, alkyl-H), 0.89 (t, J =
7.0 Hz, 3 H, alkyl-H); dC (100 MHz; CD2Cl2; Me4Si) 147.3,
131.0, 128.8, 127.9, 125.5, 119.6, 50.4, 31.9, 30.3, 29.5, 29.4,
29.3, 29.0, 26.5, 22.7, 13.9; m/z (MALDI-TOF MS, dithranol)
286.22 (100%, [M + H]+); lmax (CH2Cl2)/nm 252 (e/dm3
molꢂ1 cmꢂ1 20 100).28
Methyl-1-decyl-1H-[1,2,3]triazole-4-carboxylate (1f)
1-(4-Phenyl-1H-[1,2,3]triazol-1-yl)-undecan-1-ol (1b)
According to the general procedure, 1f was isolated as a
slightly yellow powder (370 mg, 47%). Deviating from the
general protocol, CuI (45 mg, 0.24 mmol) was used as catalyst.
After washing, the CH2Cl2 phase (300 mL) was extracted with
aqueous HEDTA solution (2 ꢁ 100 mL) and water (2 ꢁ
100 mL) to remove the copper. (Found: C, 62.81; H, 9.46; N,
15.82%. C14H25N3O2 requires C, 62.89; H, 9.42; N, 15.72%);
dH (400 MHz; CD2Cl2; Me4Si) 8.08 (s, 1 H, triazole-H), 4.39
(t, J = 7.2 Hz, 2 H, alkyl-H), 3.91 (s, 3 H, ester-H), 1.92 (mc,
2 H, alkyl-H), 1.33–1.27 (m, 14 H, alkyl-H), 0.89 (t, J =
6.8 Hz, 3 H, alkyl-H); dC (100 MHz; CD2Cl2; Me4Si): 161.3,
139.7, 127.3, 51.8, 50.6, 31.8, 30.0, 29.4, 29.3, 29.2, 28.9, 26.3,
two resoluted signals at 22.6, 13.8 (alkyl); m/z (MALDI-TOF,
According to the general procedure, 1b was isolated as a white
powder (361 mg, 39%). Deviating from the general protocol,
the click reaction was performed under microwave irradiation
(3 h, 125 1C). (Found: C, 72.0; H, 9.40; N, 13.30%.
C19H29N3O requires C, 72.3; H, 9.30; N, 13.30%); dH (400
z Safety comment: Sodium azide is a very toxic salt, personal protec-
tion precautions needs to be taken. As low-molar-mass organic azides
are potentially explosive, attention has to be taken during their
handling. Generally, when the total number of carbon (NC) plus
oxygen (NO) atoms is less than three times the total numbers of
nitrogen atoms (NN), the compound is considered as an explosive
hazard. Therefore, the compounds were prepared directly prior to use
if possible.
ꢀc
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dithranol) 268.18 (100%, [M + H]+); lmax (CH2Cl2)/nm =
273 (e/dm3 molꢂ1 cmꢂ1 1160).
1-(Biphenyl-4-yl)-4-butyl-1H-[1,2,3]triazole (2b)
According to the general protocol, 2b was isolated as a white
powder (117 mg, 21%). (Found: C, 77.90; H, 7.10; N, 15.20%.
C18H19N3 requires C, 78.00; H, 6.90; N, 15.20%); dH
(400 MHz; CD2Cl2; Me4Si) 7.84–7.76 (m, 5 H, aryl-H and
triazole-H), 7.67–7.66 (mc, 2 H, aryl-H), 7.52–7.48 (m, 2 H,
aryl-H), 7.43–7.39 (m, 1 H, aryl-H), 2.81 (t, J = 7.6 Hz, 2 H,
alkyl-H), 1.74 (mc, 2 H, alkyl-H), 1.46 (mc, 2 H, alkyl-H), 0.99
(t, J = 7.4 Hz, 3 H, alkyl-H); dC (100 MHz; CD2Cl2; Me4Si)
149.1, 141.1, 139.6, 136.5, 128.9, 128.2, 127.8, 126.9, 120.5,
118.8, 31.5, 25.3, 22.3, 13.6; m/z (MALDI-TOF MS, dithranol)
300.01 (61%, [M + Na]+), 315.95 (100%, [M + K]+); lmax
(CH2Cl2)/nm 277 (e/dm3 molꢂ1 cmꢂ1 25 100).
(1-Decyl-1H-[1,2,3]triazol-4-yl)methanol (1g)
According to the general procedure, 1g was isolated as a white
powder (933 mg, 78%). (Found: C, 65.15; H, 10.88; N,
17.75%. C13H25N3O requires: C, 65.23; H, 10.53; N,
17.56%); dH (400 MHz; CD2Cl2; Me4Si) 7.59 (s, 1 H,
triazole-H), 4.73 (s, 2 H, alkyl-H), 4.32 (t, 2 H, J 7.4, 2 H,
alkyl-H), 3.80 (s, 1 H, hydroxy-H), 1.88 (mc, 2 H, alkyl-H),
1.47–1.18 (m, 14 H, alkyl-H), 0.89 (t, J = 6.8 Hz, 3 H, alkyl-H);
dC (100 MHz; CD2Cl2; Me4Si): 148.1, 121.8, 55.9, 50.3, 31.8,
30.2, 29.5, 29.4, 29.2, 29.0, 26.4, 22.6, 13.8; m/z
(MALDI-TOF, dithranol) 240.24 (100%, [M + H]+); lmax
(CH2Cl2)/nm = 272 (e/dm3 molꢂ1 cmꢂ1 1270).
1-(4-Methoxy-phenyl)-4-phenyl-1H-[1,2,3]triazole (2c)
According to the general protocol, 2c was isolated as a white
powder (478 mg, 63%). (Found: C, 71.40; H, 5.30; N, 16.70%.
C15H14N3O requires C, 71.40; H, 5.60; N, 16.70%); dH
(400 MHz; CD2Cl2; Me4Si) 8.11 (s, 1 H, triazole-H), 7.90
(d, J = 7.6 Hz, 2 H, aryl-H), 7.68 (mc, 2 H, aryl-H), 7.45 (mc,
2 H, aryl-H), 7.36 (mc, 1 H, aryl-H), 7.04 (mc, 2 H, aryl-H),
3.88 (s, 3 H, methoxy-H); dC (100 MHz; CD2Cl2; Me4Si)
159.9, 147.9, 130.6, 128.9, 128.2, 125.6, 122.1, 118.0, 114.7,
55.6; m/z (MALDI-TOF MS, no matrix) 252.11 (100%,
[M + H]+); lmax (CH2Cl2)/nm 256 (e/dm3 molꢂ1 cmꢂ1 22 100).
Method B: general procedure for the synthesis of
1-aryl-1H-[1,2,3]triazoles (2)
Aryl bromide (5 mmol), sodium L-ascorbate (5.5 mol%), CuI
(0.5 mmol) and N,N0-dimethylethylenediamine (DMEDA,
0.8 mmol), suspended in an ethanol/water-mixture (7 : 3 ratio,
20 mL), were placed in an argon flushed flask. Upon addition
of NaN3 (10 mmol), a color change to blue was observed. The
reaction mixture was vigorously stirred under an argon stream
for at least 30 min. Subsequently, the mixture was heated
under reflux until the color changed from blue over green to a
slightly brownish yellow. Depending on the solubility of the
formed azide, the reaction mixture was allowed to cool to
room temperature or was stirred further at 80 1C.z Then the
acetylene compound (20 mmol) was added, and stirring at the
given conditions was continued for 12 h. After cooling to
room temperature, water (200 mL) was added, the precipitated
solid was filtered off and washed with water (3 ꢁ 50 mL). After
drying, the crude product was stirred in CH2Cl2 (200 mL) for 1 h.
Insoluble residues were filtered off. Additionally, the aqueous
phase of the reaction mixture was extracted with ethyl
acetate (3 ꢁ 70 mL). The ethyl acetate was removed under
reduced pressure and the residue was dissolved in CH2Cl2
(100 mL). The organic layers were combined, washed with
water (3 ꢁ 100 mL) and dried over MgSO4. The concentrated
CH2Cl2 solution was precipitated in n-pentane (150 mL)
to yield the desired product 2. When necessary purification
was achieved by flash column chromatography (silica gel,
CH2Cl2/CH3OH as eluent).
1-(3,5-Xylyl)-4-phenyl-1H-[1,2,3]triazole (2d)
According to the general protocol, 2d was isolated as a white
solid (418 mg, 67%). (Found: C, 76.87; H, 6.21; N, 16.57%.
C16H15N3 requires C, 77.08; H, 6.06; N, 16.85%); dH
(400 MHz; CD2Cl2; Me4Si) 7.97 (s, 1 H, triazole-H), 7.66
(mc, 2 H, aryl-H), 7.48 (mc, 2 H, aryl-H), 7.36 (mc, 3 H,
aryl-H), 7.11 (s, 1 H, aryl-H), 2.41 (s, 6 H, methyl-H);
dC (100 MHz; CD2Cl2; Me4Si) 148.2, 139.8, 136.9, 130.6,
130.2, 128.6, 127.9, 127.5, 120.0, 118.1, 21.0; m/z
(MALDI-TOF MS, no matrix) 250.17 (100%, [M + H]+);
lmax (CH2Cl2)/nm 258 (e/dm3 molꢂ1 cmꢂ1 20 500).
(1-Biphenyl-4-yl-1H-[1,2,3]triazol-4-yl)-methanol (2e)
According to the general protocol, 2e was isolated as a white
fibrous solid (594 mg, 59%). (Found: C, 72.10; H, 5.20; N,
16.40%. C15H13N3O requires C, 71.78; H, 5.20; N, 16.70%);
dH (400 MHz; d6-acetone; Me4Si) 8.48 (s, 1 H, triazole-H),
7.85 (mc, 4 H, aryl-H), 7.74 (mc, 2 H, aryl-H), 7.51 (mc, 2 H,
aryl-H), 7.43 (mc, 1 H, aryl-H), 4.78 (d, J = 6.4 Hz, 2 H,
alkyl-H), 4.35 (t, J = 5.8 Hz, 1 H, hydroxy-H); dC (100 MHz;
d6-acetone; Me4Si) 141.0, 139.6, 129.0, 128.1, 127.8, 126.9,
120.5, 120.2, 55.9; m/z (MALDI-TOF MS, no matrix) 252.11
(100%, [M + H]+), 274.09 (5%, [M + Na]+); lmax (CH2Cl2)/nm
275 (e/dm3 molꢂ1 cmꢂ1 24 900).
4-Decyl-1-phenyl-1H-[1,2,3]triazole (2a)
According to the general protocol, 2a was isolated as a white
solid (769 mg, 67%). (Found: C, 75.89; H, 9.64; N, 14.71%.
C18H27N3 requires: C, 75.74; H, 9.83; N, 14.54%); dH
(400 MHz; CD2Cl2; Me4Si): 7.81 (s, 1 H, triazole-H), 7.75
(d, J = 7.6 Hz, 2 H, aryl-H), 7.54 (mc, 2 H, aryl-H), 7.44 (mc,
1 H, aryl-H), 2.78 (t, J = 7.8 Hz, 2 H, alkyl-H), 1.74 (mc, 2 H,
alkyl-H), 1.46–1.23 (m, 14 H, alkyl-H), 0.90 (t, J = 7.2 Hz,
3 H, alkyl-H); dC (100 MHz; CD2Cl2; Me4Si): 149.1, 137.4,
129.6, 128.2, 120.2, 118.8, 31.9, 29.6, 29.4, 23.3, 12.2, 25.6,
22.7, 13.9; m/z (MALDI-TOF MS, dithranol): 286.23 (100%,
[M + H]+); lmax (CH2Cl2)/nm 252 (e/dm3 molꢂ1 cmꢂ1 9300).
(1-(4-Methoxyphenyl)-1H-[1,2,3]triazol-4-yl)methanol (2f)
According to the general protocol, 2f was isolated as a white
solid (386 mg, 61%). (Found: C, 58.60; H, 5.50; N, 20.10%.
C10H11N3O2 requires C, 58.50; H, 5.40; N, 20.50%). dH
(400 MHz; CD2Cl2; Me4Si) 7.93 (s, 1 H, triazole-H), 7.64
(mc, 2 H, aryl-H), 7.05 (mc, 2 H, aryl-H), 4.84 (d, J = 5.6 Hz,
2 H, alkyl-H), 3.88 (s, 3 H, methoxy-H), 2.35 (t, J = 2.0 Hz,
ꢀc
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1 H, hydroxy-H); dC (100 MHz; CD2Cl2; MeSi4) 159.9, 148.1,
130.5, 122.1, 120.1, 114.7, 56.4, 55.6; m/z (MALDI-TOF MS,
no matrix) 205.95 (14, [M + H]+), 227.95 (67, [M + Na]+),
Bis(2-phenylpyridinato-N,C2)((1-biphenyl-4-yl-1H-
[1,2,3]triazol-4-yl) carboxylate-N3,O) iridium(III) (5a)
According to the general protocol, IrIII complex 5a was
isolated after column chromatography (Al2O3, CH2Cl2/
MeOH (98 : 2 ratio)) as a yellow solid (7 mg, 27%). (Found:
C, 58.10; H, 3.80; N, 9.00%. C37H26IrN5O2 requires C: 58.10,
H: 3.43, N: 9.16%); dH (400 MHz; CD2Cl2; Me4Si): 8.81
(d, J = 5.6 Hz, 1 H), 8.57 (s, 1 H), 7.93 (mc, 3 H), 7.84–7.72
(m, 6 H), 7.68–7.62 (m, 4 H), 7.49 (t, J = 8.0 Hz, 2 H), 7.41
(mc, 1 H), 7.22 (mc, 1 H), 7.08 (mc, 1 H), 6.95 (mc, 2 H), 6.80
(mc, 2 H), 6.42 (d, J = 7.6 Hz, 1 H), 6.18 (d, J = 7.6 Hz, 1 H);
dC NMR (CD2Cl2; 100 MHz; Me4Si) 168.2, 167.8, 149.1,
148.8, 148.4, 147.8, 145.6, 144.4, 144.3, 143.6, 142.9, 139.1,
137.5, 137.4, 135.2, 132.5, 132.0, 129.4, 129.2, 129.0, 128.4,
128.2, 127.0, 124.7, 124.0, 122.6, 122.2, 121.8, 121.2, 121.0,
119.1, 118.7; m/z (HiResESI, CH2Cl2/CH3OH): 501.0 (66%,
243.93 (100%, [M
(e/dm3 molꢂ1 cmꢂ1 10 900).
+
K]+); lmax (CH2Cl2)/nm 259
(1-(3,5-Xylyl)-1H-[1,2,3]triazol-4-yl)methanol (2g)
According to the general protocol, 2g was isolated as slightly
pink needles (428 mg, 70%). (Found: C, 64.80; H, 6.50; N,
20.70%. C11H13N3O: requires C, 65.00; H, 6.50; N, 20.70%);
dH (400 MHz; CD2Cl2; Me4Si) 7.97 (s, 1 H, triazole-H), 7.36
(s, 2 H, aryl-H), 7.11 (s, 1 H, aryl-H), 4.84 (d, J = 5.2 Hz, 2 H,
alkyl-H), 2.41 (s, 6 H, methyl-H), 2.23 (t, J = 6.0 Hz, hydroxy-H);
dC (100 MHz; CD2Cl2; Me4Si) 148.2, 139.8, 136.9, 130.2,
120.0, 118.1, 56.3, 21.0; m/z (MALDI-TOF MS, no matrix)
204.02 (12%, [M + H]+), 226.02 (100, [M + Na]+), 241.98
(93%, [M + K]+); lmax (CH2Cl2)/nm 252 (e/dm3 molꢂ1 cmꢂ1
8300) nm.
[Ir(ppy)2]+), 788.0 (100%, [M
+
Na]+), 805.9 (48%,
[M + Na + H2O]+), 820.0 (42%, [M + Na + CH3OH]+),
1265.1 (14%, [M + Ir(ppy)2]+), 1553.0 (38%, [2 ꢁ M + Na]+).
[(ppy)2Ir-l-(OH)]2: Tetrakis(2-phenylpyridinato-N,C2)-
(l-dihydroxy)diiridium(III) (3)
Bis(2-phenylpyridinato-N,C2)((1-(4-methoxyphenyl)-1H-
[1,2,3]triazol-4-yl) carboxylate-N3,O) iridium(III) (5b)
A mixture of IrCl3 ꢁ 3H2O (257 mg, 0.73 mmol) and 2-phenyl-
pyridine (276 mg, 1.71 mmol) in ethoxyethanol/H2O (12.5 mL,
3 : 1 ratio) was refluxed under argon for 4.5 h. Subsequently,
an excess of NaOH (1.25 g, 0.03 mol) dissolved in H2O
(12.5 mL) was added and stirring was continued under reflux
for 2 h. After cooling to room temperature, H2O (25 mL) was
added, and the orange-brown precipitate was filtered off. The
solid was dissolved in CH2Cl2 (15 mL), and the filtered
solution was treated with NaOH solution (1.68 g, 0.04 mol
in 4.5 mL H2O) at reflux for 6 h. Afterwards, the solvent was
evaporated and H2O (125 mL) was added. The crude product
was filtered off and washed with n-pentane (10 mL) and
diethyl ether (10 mL). Further purification was achieved by
redissolving the product in CH2Cl2 followed by precipitation
in n-pentane to yield 3 as a brown powder (295 mg, 78%).
(Found: C, 50.82; H, 3.34; N, 5.24%. C44H34Ir2N4O2 requires:
C, 51.05; H, 3.31; N, 5.41%); dH (400 MHz; CD2Cl2; Me4Si)
8.71 (d, J = 5.7 Hz, 4 H), 7.89 (d, J = 8.1 Hz, 4 H), 7.63 (dd,
J = 7.5 Hz, J = 1.5 Hz, 4 H), 7.57 (d, J = 6.5 Hz, 4 H), 6.75
(mc, 4 H), 6.66 (mc, 4 H), 6.54 (mc, 4 H), 5.94 (d, J = 6.5 Hz, 4 H),
–1.45 (s, 2 H); dC (100 MHz; CD2Cl2; Me4Si) 168.9, 150.2,
148.3, 144.8, 135.6, 131.3, 128.5, 123.6, 121.1, 119.7, 118.0.
According to the general protocol, IrIII complex 5b was
isolated after gradient column chromatography (Al2O3,
CH2Cl2 - CH2Cl2/MeOH (98 : 2 ratio)) as a yellow powder
(11 mg, 39%). Due to the instability of the product, only a
limited characterization could be carried out. dH (400 MHz;
CD2Cl2; Me4Si) 8.79 (d, J = 6.4 Hz, 1 H), 8.40 (s, 1 H),
7.97–7.86 (m, 3 H), 7.84–7.76 (m, 2 H), 7.65 (t, J = 7.6 Hz,
2 H), 7.56 (mc, 2 H), 7.21 (mc, 1 H), 7.08 (mc, 1 H), 7.01
(mc, 2 H), 6.94 (mc, 2 H), 6.79 (mc, 2 H), 6.40 (d, J = 8.0 Hz,
1 H), 6.17 (d, J = 8.0 Hz, 1 H), 3.85 (s, 3 H, methoxy-H); m/z
(HiResESI, CH2Cl2/CH3OH): 501.0 (88%, [Ir(ppy)2]+), 742.0
(100%, [M + Na]+), 760.0 (54%, [M + Na + H2O]+), 774.0
(24%, [M + Na + CH3OH]+), 1220.1 (14%, [M + Ir(ppy)2]+),
1461.1 (20%, [2 ꢁ M + Na]+).
Bis(2-phenylpyridinato-N,C2)((1-(3,5-xylyl)-1H-[1,2,3]triazol-4-yl)
carboxylate-N3,O) iridium(III) (5c)
According to the general protocol, IrIII complex 5c was
isolated after gradient column chromatography (Al2O3,
CH2Cl2 - CH2Cl2/MeOH (95 : 5 ratio)) as yellow solid
(8 mg, 21%). Due to the pronounced instability of the
product, only a limited characterization could be carried out.
m/z (HiRes-ESI, CH2Cl2/MeOH) 501.0 (54%, [Ir(ppy)2]+),
740.0 (100%, [M + Na]+), 758.0 (74%, [M + Na + H2O]+),
General procedure for the synthesis of the IrIII complexes
A 10 mL microwave vial was equipped with 3 (40 mg,
0.04 mmol), 2 (0.10 mmol) and CHCl3 (5 mL) and was sealed.
The reaction mixture was degassed for 30 min with argon at
room temperature and then heated to 70 1C under stirring for
12 h. After cooling to room temperature, the reaction mixture
was added dropwise into n-pentane (30 mL). The yellow
precipitate was collected by filtration and washed with
n-pentane. Subsequently, the precipitate was dissolved in
CH2Cl2 (50 mL), washed with water (3 ꢁ 15 mL) and dried
over MgSO4. The concentrated CH2Cl2 phase was poured into
n-pentane to precipitate the crude product. The iridium(III)
complex was further purified by gradient column chromato-
graphy (Al2O3, CH2Cl2 - CH2Cl2/MeOH (99 : 1 ratio)).
772.0 (48%, [M
+ Na +
CH3OH]+), 1217.1 (28%,
[M + Ir(ppy)2]+), 1455.2 (64%, [2 ꢁ M + Na]+).
[(ppy)2Ir(pic)]: Bis(2-phenylpyridinato-N,C2)(picolinate-N,O)
iridium(III) (6)
According to the general protocol, IrIII complex 6 was isolated
as dark yellow crystals (15 mg, 30%). (Found: C, 54.01; H,
3.24; N, 6.60%. C28H20IrN3O2 requires C, 54.01; H, 3.24; N,
6.75%); dH (400 MHz; CD2Cl2; Me4Si): 8.71 (d, J = 5.6 Hz,
1 H), 8.26 (d, J = 7.6 Hz, 1 H), 7.95 (d, J = 8.0 Hz, 1 H), 7.91
(t, J = 7.6 Hz, 1 H), 7.89 (d, J = 8.0 Hz, 1 H), 7.80–7.73
(m, 3 H), 7.67 (d, J = 8.0 Hz, 2 H), 7.52 (d, J = 6.0 Hz, 1 H),
ꢀc
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7.35 (mc, 1 H), 7.17 (mc, 1 H), 7.00 (mc, 1 H), 6.97 (t, J =
7.2 Hz, 1 H), 6.94 (t, J = 7.2 Hz, 1 H), 6.81 (mc, 2 H), 6.40
(d, J = 6.8 Hz, 1 H), 6.21 (d, J = 7.2 Hz, 1 H); dC (100 MHz;
CD2Cl2; Me4Si): 172.4, 168.6, 167.5, 152.2, 149.6, 148.7, 148.4,
148.2, 147.3, 144.4, 144.2, 137.7, 137.3, 137.2, 132.3, 129.8,
129.4, 128.0, 124.4, 124.1, 122.4, 122.3, 121.5, 121.1, 119.1,
118.6; m/z (MALDI-TOF MS, dithranol) 1124.41 (100,
[M + (ppy)2Ir]+), 646.21 (25, [M + Na]+), 624.21 (52,
[M + H]+), 501.17 (60, [(ppy)2Ir]+); lmax (CH2Cl2)/nm 477
(e/dm3 molꢂ1 cmꢂ1 680), 429 (3350), 398 (4350), 264 (39 500);
lPL (CH2Cl2)/nm 505; FPL (CH2Cl2) 0.29.
8 (a) C. K.-L. Li, R. W.-Y. Sun, S. C.-F. Kui, N. Zhu and
C.-M. Che, Chem.–Eur. J., 2006, 12, 5253; (b) M. A. Ivanov,
M. V. Puzyk and K. P. Balashev, Opt. Spectrosc., 2006, 100, 382;
(c) K. M.-C. Wong, X. Zhu, L.-L. Hung, N. Zhu, V. W.-W. Yam
and H.-S. Kwok, Chem. Commun., 2005, 2906.
9 M. A. Baldo, S. Lamansky, P. E. Burrows, M. E. Thompson and
S. R. Forrest, Appl. Phys. Lett., 1999, 75, 4.
10 K. A. McGee and K. R. Mann, Inorg. Chem., 2007, 46, 7800.
11 I. M. Dixon, J.-P. Collin, J.-P. Sauvage, L. Flamigni, S. Encinas
and F. Barigeletti, Chem. Soc. Rev., 2000, 29, 385.
12 (a) N. D. McDaniel, F. J. Coughlin, L. L. Tinker and S. Bernhard,
J. Am. Chem. Soc., 2008, 130, 210; (b) B. Schmid, F. O. Garces and
R. J. Watts, Inorg. Chem., 1994, 33, 9.
13 (a) X. Gu, T. Fei, H. Zhang, H. Xu, B. Yang, Y. Ma and X. Liu,
J. Phys. Chem. A, 2008, 112, 8387; (b) X. Zeng, M. Tavasli,
I. Perepichka, A. S. Batsanov, M. R. Bryce, C.-J. Chiang,
C. Rothe and A. P. Monkman, Chem.–Eur. J., 2008, 14, 933;
(c) D. Di Censo, S. Fantacci, F. De Angelis, C. Klein, C. Evans,
K. Kalyanasundaram, H. J. Bolink, M. Gratzel and
M. K. Nazeeruddin, Inorg. Chem., 2008, 47, 980.
14 (a) K. Dedeian, P. I. Djurovich, F. O. Garces, G. Carlson and
R. J. Watts, Inorg. Chem., 1991, 30, 1685; (b) M. E. Thompson,
P. I. Djorovic, S. Barlow and S. R. Marder, Organometallic
Complexes for Optoelectronic Applications, in Comprehensive
Organometallic Chemistry, ed. D. O’Hare, Elsevier, Oxford,
2007, vol. 12, ch. 12.4, pp. 101–194.
15 A. B. Tamayo, B. D. Alleyne, P. I. Djurovich, S. Lamansky,
I. Tsyba, N. N. Ho, R. Bau and M. E. Thompson, J. Am. Chem.
Soc., 2003, 125, 7377.
Acknowledgements
The authors acknowledge the Dutch Polymer Institute (DPI),
the Nederlandse Organisatie voor Wetenschappelijk Onderzoek
(NWO, VICI award for U.S.S.) and the Fonds der Chemischen
Industrie for financial support. We also thank Rebecca
Eckardt (elemental analysis) and Tina Erdmenger (MALDI-
TOF MS) for help with the respective measurements and
Dr. Michael Jager for helpful comments.
16 (a) R. Ragni, E. A. Plummer, K. Brunner, J. W. Hofstraat,
F. Babudri, G. F. Farinola, F. Naso and L. De Cola, J. Mater.
Chem., 2006, 16, 1161; (b) A. Tsuboyama, H. Iwawaki,
M. Furugori, T. Mukaide, J. Kamatani, S. Igawa, T. Moriyama,
S. Miura, T. Takiguchi, S. Okada, M. Hoshino and K. Ueno,
J. Am. Chem. Soc., 2003, 125, 12971.
17 (a) K. Saito, N. Matsusue, H. Kanno, Y. Hamada, H. Takahashi
and T. Matsumura, Jpn. J. Appl. Phys., 2004, 43, 2733;
(b) H. Konno and Y. Sasaki, Chem. Lett., 2003, 252.
Notes and references
1 H. Yersin, Highly Efficient OLEDs with Phosphorescent Materials,
Wiley-VCH, Weinheim, Germany, 2008.
2 (a) C. Ulbricht, B. Beyer, C. Friebe, A. Winter and U. S. Schubert,
Adv. Mater., 2009, 21, 4418; (b) E. Holder, B. M. W. Langeveld
and U. S. Schubert, Adv. Mater., 2005, 17, 1109;
(c) R. Shunmugam and G. N. Tew, Macromol. Rapid Commun.,
2008, 29, 1355; (d) P.-T. Chou and Y. Chi, Chem.–Eur. J., 2007, 13,
380; (e) R. Vivas-Reyes, F. Nunez-Zarur and E. Martinez, Org.
Electron., 2008, 9, 625; (f) V. Marin, E. Holder, R. Hoogenboom
and U. S. Schubert, Chem. Soc. Rev., 2007, 36, 618; (g) P.-T. Chou
and Y. Chi, Eur. J. Inorg. Chem., 2006, 3319.
3 (a) A. C. Grimsdale, K. L. Chan, R. E. Martin, P. G. Jokisz and
A. B. Holmes, Chem. Rev., 2009, 109, 897; (b) E. Tekin, D. A. M.
Egbe, J. M. Kranenburg, C. Ulbricht, S. Rathgeber, E. Birckner,
N. Rehmann, K. Meerholz and U. S. Schubert, Chem. Mater.,
2008, 20, 2727; (c) O. Nuyken, S. Jungermann, V. Wiederhirn,
E. Bacher and K. Meerholz, Monatsh. Chem., 2006, 137, 811;
(d) C.-W. Chiu, T. J. Chow, C.-H. Chuen, H.-M. Lin and
Y.-T. Tao, Chem. Mater., 2003, 15, 4527.
4 (a) K. Walzer, B. Maening, M. Pfeiffer and K. Leo, Chem. Rev.,
2007, 107, 1109; (b) N. Koch, ChemPhysChem, 2007, 8, 1438;
(c) M. Pfeiffer, S. R. Forrest, X. Zhou and K. Leo, Org. Electron.,
2003, 4, 21; (d) M. T. Bernius, M. O’Brien, J. Inbasekaran and
W. Wu, Adv. Mater., 2000, 12, 1737; (e) J. H. Burroughes,
D. C. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay,
R. H. Friend, P. L. Burns and A. B. Holmes, Nature, 1990, 347, 539.
5 (a) N. Rehmann, C. Ulbricht, A. Kohnen, P. Zacharias,
M. C. Gather, D. Hertel, E. Holder, K. Meerholz and
U. S. Schubert, Adv. Mater., 2008, 20, 129; (b) B. C. Krummacher,
V.-E. Choong, M. K. Mathai, S. A. Choulis, F. So, F. Jermann,
T. Fiedler and M. Zacahu, Appl. Phys. Lett., 2006, 88, 113506;
(c) R. C. Evans, P. Douglas and C. J. Winscom, Coord. Chem.
Rev., 2006, 250, 2093; (d) J. Slinker, D. Bernards, P. L. Houston,
H. D. Abruna, S. Bernhard and G. G. Malliaras, Chem. Commun.,
2003, 2392; (e) B. W. D’Andrade, J. Brooks, V. Adamovich,
M. E. Thompson and S. R. Forrest, Adv. Mater., 2002, 14, 1032.
6 (a) F. Niedermaier, O. Kwon, K. Zojer, S. Kappaun, G. Trimmel,
K. Mereiter and C. Slugovc, Dalton Trans., 2008, 4006;
(b) Y. Kawamura, J. Brooks, J. J. Brown, H. Sasabe and
C. Adachi, Phys. Rev. Lett., 2006, 96, 017404; (c) B. Ma,
P. I. Djurovich and M. E. Thompson, Coord. Chem. Rev., 2005,
249, 1501.
18 K. Dedeian, J. Shi, N. Shepherd, E. Forsythe and D. C. Morton,
Inorg. Chem., 2005, 44, 4445.
19 (a) E. Orselli, G. S. Kottas, A. E. Konradsson, P. Coppo,
R. Frohlich, L. De Cola, A. Van Dijken, M. Buchel and
H. Borner, Inorg. Chem., 2007, 46, 11082; (b) S. C. Lo,
C. P. Shipley, R. N. Bera, E. Harding, A. R. Cowley, P. L. Burn
and I. D. W. Samuel, Chem. Mater., 2006, 18, 5119.
20 (a) C. R. Becer, R. Hoogenboom and U. S. Schubert, Angew.
Chem., Int. Ed., 2009, 48, 4900; (b) D. Fournier, R. Hoogenboom
and U. S. Schubert, Chem. Soc. Rev., 2007, 36, 1369;
(c) C. W. Tornø, C. Christensen and M. Meldal, J. Org. Chem.,
2002, 67, 3057; (d) V. V. Rostovtsev, L. G. Green, V. V. Fokin and
K. B. Sharpless, Angew. Chem., Int. Ed., 2002, 41, 2596;
(e) H. K. Kolb, M. G. Finn and K. B. Sharpless, Angew. Chem.,
Int. Ed., 2001, 40, 2004; (f) R. Huisgen, Angew. Chem., 1963, 75,
604; (g) R. Huisgen, Angew. Chem., 1963, 75, 742.
21 H. Struthers, T. L. Mindt and R. Schibli, Dalton Trans., 2010, 39,
675.
22 B. Happ, C. Friebe, A. Winter, M. D. Hager, R. Hoogenboom and
U. S. Schubert, Chem.–Asian J., 2009, 4, 154.
23 B. Schulze, C. Friebe, M. D. Hager, A. Winter, R. Hoogenboom,
H. Goerls and U. S. Schubert, Dalton Trans., 2009, 787.
24 Y. Li, J. C. Huffman and A. H. Flood, Chem. Commun., 2007, 2692.
25 R. M. Meudtner, M. Ostermeier, R. Goddard, C. Limberg and
S. Hecht, Chem.–Eur. J., 2007, 13, 9834.
26 D. Schweinfurth, K. I. Hardcastle and U. H. F. Bunz, Chem.
Commun., 2008, 2203.
27 M. Felici, P. Contreras-Carballada, Y. Vida, J. M. M. Smits,
R. J. M. Nolte, L. De Cola, R. M. Williams and M. C. Feiters,
Chem.–Eur. J., 2009, 15, 13124.
28 B. Beyer, C. Ulbricht, C. Friebe, A. Winter, D. Escudero,
L. Gonzalez and U. S. Schubert, Organometallics, 2009, 28, 5478.
29 Y. Ju, D. Kumar and R. S. Varma, J. Org. Chem., 2006, 71, 6697.
30 A stronger deactivation of the CuI catalyst by the propargylic acid
(pKa of 3.40) in comparison to the decanoic acid derivative can be
assumed. For the pKa value see: J. Radell, B. W. Brodman,
A. Hirshfeld and E. D. Bergmann, J. Phys. Chem., 1965, 69, 928.
7 P. Jolliet, M. Gianni, A. von Zelewsky, G. Bernardinelli and
H. Stoeckli-Evans, Inorg. Chem., 1996, 35, 4883.
ꢀc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010
2632 | New J. Chem., 2010, 34, 2622–2633

View Article Online
31 C. Haensch, T. Erdmenger, M. W. M. Fijten, S. Hoeppener and
U. S. Schubert, Langmuir, 2009, 25, 8019.
41 M.-L. Xu, R. Zhou, G.-Y. Wang, Q. Xiao, W.-S. Dua and
G.-B. Che, Inorg. Chim. Acta, 2008, 361, 2407.
32 C.-Z. Tao, X. Cui, J. Li, A.-X. Liu, L. Liu and Q.-X. Guo,
Tetrahedron Lett., 2007, 48, 3525.
33 J. Anderson, U. Madsen, F. Bjorkling and X. Liang, Synlett, 2005,
2209.
42 Remeasuring the NMR sample of 5b after two weeks showed
almost full degradation of the complex; this effect was even
observed after one day for 5c.
43 (a) C. Bianchini, A. Meli, M. Peruzzini and F. Vizza, J. Am. Chem.
Soc., 1990, 112, 6726; (b) M. Ladwig and W. Kaim, J. Organomet.
Chem., 1992, 439, 79; (c) K. Fujita, S. Furukawa and
R. Yamaguchi, J. Organomet. Chem., 2002, 649, 289;
(d) T. Suzuki, K. Morita, M. Tsuchida and K. Hiroi, J. Org.
Chem., 2003, 68, 1601; (e) A. Gabrielsson, P. van Leeuwen and
W. Kaim, Chem. Commun., 2006, 4926; (f) K. Fujita, N. Tanino
and R. Yamaguchi, Org. Lett., 2007, 9, 109; (g) S. Kiyooka,
Y. Wada, M. Ueno, T. Yokoyama and R. Yokoyama, Tetra-
hedron, 2007, 63, 12695.
34 F. Himo, T. Lovell, R. Hilgraf, V. V. Rostovtsev, L. Noodleman,
K. B. Sharpless and V. V. Fokin, J. Am. Chem. Soc., 2005, 127, 210.
35 For single-crystal X-ray diffraction analysis of 1,4-diaryl-
substituted 1H-[1,2,3]triazoles see, e.g.: (a) H. Hu, A. Zhang,
L. Ding, X. Lei and L. Zhang, Molecules, 2008, 13, 556;
(b) W. Qu, M.-P. Kung, C. Hou, S. Oya and H. F. Kung,
J. Med. Chem., 2007, 50, 3380; (c) K. Barral, A. D. Moorhouse
and J. E. Moses, Org. Lett., 2007, 9, 1809; (d) R. E. Marsh,
Acta Crystallogr., Sect. B: Struct. Sci., 2004, 60, 252;
(e) Z.-X. Wang and H.-L. Qin, Chem. Commun., 2003, 2450.
36 V. Grushin, V. A. Petrov, Y. Wang, E. I. du Pont de Nemours and
Company (Wilmington, DE, U.S.), US Pat., 6 979 739, 2005.
37 Recently, the first X-ray structure of a related m-hydroxy-bridged
dimeric IrIII complex was reported. The preparation of this
complex under comparable reaction conditions gave further
evidence for the formation of the expected dimeric species 3. For
the X-ray structure see: S. K. Meier, K. J. H. Young, D. H. Ess,
W. J. Tenn, J. Oxgaard, W. A. William and R. A. Periana,
Organometallics, 2009, 28, 5239.
44 A.
V.
Makarycheva-Mikhailova,
P.
V.
Gushchin,
M. N. Kopylovich, I. N. Ganebnykh, V. N. Charushin,
M. Haukka, A. J. L. Pombeiro and V. Y. Kukushkin, Inorg.
Chem. Commun., 2006, 9, 869.
45 (a) R. H. Blessing, Acta Crystallogr., Sect. A: Fundam. Crystallogr.,
1995, 51, 33; (b) G. M. Sheldrick, SADABS, Bruker AXS Inc,
Madison, WI, 1998.
46 (a) R. W. W. Hooft, COLLECT, Data Collection Software, Nonius
B.V., Delft, The Netherlands, 1998; (b) Z. Otwinowski and
W. Minor, Processing of X-Ray Diffraction Data Collected in
Oscillation Mode in Methods in Enzymology, Macromolecular
Crystallography, Part A, ed. C. W. Carter and R. M. Sweet,
Academic Press, 1997, vol. 276, pp. 307–326.
47 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
48 G. M. Sheldrick, SHELX-97, Programs for Crystal Structure
Analysis (Release 97–2), Gottingen University, Gottingen,
Germany, 1998.
38 For the m-dicholoro-bridged IrIII precursor complex no reaction
with 1H-[1,2,3]triazoles 1 or 2 could be observed.
39 In all other cases no coordination of 1 or 2 to the IrIII center could
be observed under the applied reaction conditions.
40 N. Boechat, J. C. S. da Costa, J. S. Mendonca, K. C. Paes,
E. L. Fernandes, P. S. M. Oliveira, T. R. A. Vasconcelos and
M. V. N de Souza, Synth. Commun., 2005, 35, 3187.
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