Synthesis and Catalytic Applications of Multinuclear Gold(I)-1,2,3-Triazolylidene Complexes

Article abstract of DOI:10.1002/ejic.202001022

A series of mono- to trinuclear gold(I) complexes (1–3) supported by oxo-functionalized 1,2,3-triazolylidenes have been prepared. All new compounds were fully characterized by means of ¹H and ¹³C NMR spectroscopy, elemental analyses, and in the case of complexes 1 and 2 by x-ray diffraction. The catalytic performance of the new triazolylidene gold complexes was tested in several hydroelementation and cyclization processes employing a variety of alkynes as starting materials. According to the overall results, the trinuclear complex 3 displayed the highest catalytic activity in all processes, providing good to excellent yields under mild reaction conditions.

Full text of DOI:10.1002/ejic.202001022

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Synthesis and Catalytic Applications of Multinuclear Gold
(
I)-1,2,3-Triazolylidene Complexes
[a]
[a]
[a]
David Rendón-Nava, Alejandro Álvarez-Hernández,* and Daniel Mendoza-Espinosa*
A series of mono- to trinuclear gold(I) complexes (1–3)
supported by oxo-functionalized 1,2,3-triazolylidenes have been
prepared. All new compounds were fully characterized by
means of H and C NMR spectroscopy, elemental analyses, and
in the case of complexes 1 and 2 by x-ray diffraction. The
catalytic performance of the new triazolylidene gold complexes
was tested in several hydroelementation and cyclization
processes employing a variety of alkynes as starting materials.
According to the overall results, the trinuclear complex 3
displayed the highest catalytic activity in all processes, provid-
ing good to excellent yields under mild reaction conditions.
1
1
1
1
1
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13
Introduction
In general, the coordination chemistry of 1,2,3-triazolyli-
[7]
denes is dominated by monotopic species. The development
and preparation of ligand platforms allowing the generation of
Since the discovery of bottleable N-heterocyclic carbenes
[
8]
[9]
[10]
(NHCs) in 1991, they have attracted extraordinary attention in
di- trinuclear and tetranuclear metal complexes based on
MICs have been reported recently in the literature. Along with
the increasing interest on developing cleaner chemical proc-
esses, particular attention has targeted the design and synthesis
of multinuclear metal complexes as they usually display
enhanced reactivity and selectivity over their monometallic
homogeneous catalysis either as free-ligands or when coordi-
nated to transition o main group metals.[1] Owing to their
strong σ-donor capacity, air stability, and low toxicity, NHCs
have been considered as ideal alternatives to the more
commonly used phosphines and amino monodentate li-
gands.[2] Due to the particular features of these carbon-based
species, the design and preparation of new types of NHC
ligands is a constant effort in organometallic chemistry.
[11]
counterparts.
A number of these multinuclear complexes
have demonstrated to be highly efficient as catalysts for a
variety of chemical reactions including several cross coupling
processes, hydroaminations, olefin polymerizations, among
[2]
Mesoionic (MIC) 1,2,3-Triazolylidenes are an important
subclass of NHC ligands that has presented an exponential
[12]
others.
The improvement in the catalytic and selectivity
[3]
growth in recent years. These type of ligands where the
carbene center is not flanked by heteroatoms in both sides of
their structures, have attracted a great deal of attention as they
display enhanced σ-donor properties compared to classical N-
heterocyclic carbenes while, their mesoionic character improves
their ability to stabilize different oxidation states. Their 1,2,3-
triazolium precursors, can be easily prepared by means of the
copper(I) catalyzed “click” cycloaddition of alkynes and azides
achieved by these catalysts is attributed mainly to cooperative
interactions between proximal metal centers where features
such as intermetallic distances, three-dimensional structures,
and the enhanced probability of interaction with the substrates
[13]
play a key role.
[4]
In line with our interest in multimetallic complexes for
catalytic applications, we report herein the preparation and full
characterization of a series of mono- to tri-triazolylidene gold
complexes (1–3) which are obtained by the one step treatment
of triazolium precursors (I–III) with KHMDS in presence of the
[5]
[6]
(CuAAC) and their subsequent N-alkylation. Because of the
ease in structural modification in the triazolylidene frameworks,
great topological diversity is achieved by modification of the
substituent appended at the N1-, N3- and C4-positions. This
level of substitution strongly affects the electronic and steric
properties of the resulting mesoionic carbenes and their
respective metal complexes.
AuCl(SMe ). Complexes 1–3 were tested in the hydration and
2
hydroamination of terminal alkynes and in the preparation of
oxazolines by the cyclization of propargylic amines. In all
catalytic processes, the trinuclear complex 3 displayed the best
performance of the series, suggesting cooperative effects in the
multinuclear complexes. Details of the full characterization of
the new complexes and their catalytic comparison will be
discussed.
[
a] D. Rendón-Nava, A. Álvarez-Hernández, Dr. D. Mendoza-Espinosa
Área Académica de Química
Universidad Autónoma del Estado de Hidalgo
Carretera Pachuca-Tulancingo Km. 4.5, Mineral de la Reforma, Hidalgo
4
2090, Mexico
E-mail: alvarez@uaeh.edu.mx
daniel_mendoza@uaeh.edu.mx
Results and Discussion
The synthesis of the 1,2,3-triazolium salt precursors I–III was
performed according to the literature procedure by means of a
copper catalyzed cycloaddition (CuAAC) of mesityl azide with
the appropriate alkyne, followed by N-quaternarization with
https://www.uaeh.edu.mx/campus/icbi/investigacion/quimica/index.html
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/ejic.202001022
Part of the “Inorganic Chemistry in Latin America” Special Collection.
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[
14]
methyl iodide. A comparison of the sigma-donation of the
complex 1 by the reaction of triazolium I with Ag O and the
2
1
2
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4
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8
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0
1
2
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0
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0
1
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0
1
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5
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7
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0
1
2
3
4
5
6
7
1
MIC salts I–III, using the already available JCH coupling
constants from 1H NMR spectra was obtained.
subsequent addition of AuCl(SMe ) resulted in yields lower than
2
[14b]
The coupling
35%.
values for I (202.76 Hz), II (201.81 Hz) and III (200.42 Hz) are
consistent with a higher σ-donation compared to classical NHC
ligands (208–223 Hz). In order to get access to the desired gold
NMR spectroscopy studies confirmed the formation of
complex 1 by the disappearance of the acidic CH+ proton in
1
the H-NMR spectra (around 9 ppm) and the observation of a
1
3
(I) triazolylidene complexes, we initially tested the reaction of
low field signal at 173.2 ppm in C NMR, corresponding to the
carbenic carbon bound to gold. To gain further insight into the
structural features of complex 1, single crystals were grown
from a mixture of dichloromethane-THF at room temperature
(Figure 1).
the triazolium salt I with slight excess of potassium hexameth-
yldisilazane (1.3 equiv.) and one equivalent of AuCl(SMe ) in
2
THF at À 78°C. After work up and purification by column
chromatography, complex 1 was isolated in 63% yield as an air
stable yellow solid (Scheme 1). Our attempts to generate
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
Complex 1 crystallizes in the triclinic system with the P-1
space group, and the monomeric structure display a carbene-
gold bond distance of 2.028(11) Å and a AuÀ I bond distance of
2
.5412(9) Å, which are in the range of recently reported MICÀ Au
[15]
analogues.
The coordination of the gold center to the
triazolylidene and the iodine atom results in a slightly distorted
linear geometry with a C5À Au1À I1 angle of 176.5(2)°, and no
short contact with the phenoxy moiety is observed.
Motivated by the successful metalation of the monotriazo-
lium salt I, we followed a similar strategy for the preparation of
the multinuclear triazolylidene complexes. Thus, as shown in
Scheme 2, the one-pot reaction of the triazolium salts II and III
with excess of KHMDS and the required amounts of the AuCl
Scheme 1. Synthesis of triazolylidene complex 1.
(
SMe ), produces complexes 2 and 3 in adequate yields (73–
2
8
1%). Purification of the complexes was achieved by chroma-
tography column using a mixture of dicloromethane/ethanol as
eluent and interestingly, despite of the high degree of metal-
ation in complexes 2 and 3, all of them display excellent
solubility in benzene, toluene and a variety of chlorinated
solvents.
Characterization of complexes was achieved by NMR
spectroscopy, melting point, and elemental analysis. As ex-
1
pected for complexes 2 and 3, the H NMR spectra no longer
display the acidic CH-imidazolium protons while, only one set
of resonances for the N-methyl, methylene and mesityl are
Figure 1. Molecular structure of the of complex 1. Ellipsoids are shown at
5
0% probability.
Scheme 2. Synthesis of complexes 2 and 3.
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1
3
observed. C-NMR spectroscopy shows a single carbene-gold
peak located at 173.1 and 173.2 for the di- and trinuclear
complexes, respectively. Overall, the NMR patters of 2 and 3 are
consistent with a C and C symmetry in solution, respectively,
Table 1. Hydroamination of phenylacetylene with several aniline substra-
tes.
1
2
3
4
5
6
7
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0
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0
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7
8
9
0
1
2
3
4
5
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2
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5
6
7
[
a]
2
3
and discard the presence of conformational isomers.
Despite the numerous attempts to crystallize complexes 2
and 3, we were unsuccessful on obtaining appropriate x-ray
quality samples. The best set of single crystals for complex 2
were obtained from the slow evaporation of a mixture of THF-
dichloromethane yielding colorless needles. Although full
refinement could not be obtained owing to the low quality of
Entry
R
[Cat]
Conversion
6 h [%]
Conversion
3 h [%]
[
b]
[b]
1
2
3
4
5
6
7
8
9
10
Ph
Ph
Ph
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
96
99
99
69
82
93
87
92
95
70
84
96
56
81
89
62
88
96
48
70
88
55
78
91
46
77
92
37
66
82
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
4-(OMe)Ph
4-(OMe)Ph
4-(OMe)Ph
4-(NO
4-(NO )Ph
4-(NO
2,4,6-(Me )Ph
3
2,4,6-(Me )Ph
2,4,6-(Me )Ph
[16]
the crystals, the molecular structure and atom connectivity of
complex 2 is unambiguous and allow its discussion and
comparison. As depicted in Figure 2, complex 2 crystallizes in
the triclinic P-1 space group with the asymmetric unit
displaying Au1À C1 and Au2À C2 bond distances of 2.07(2) and
2
)Ph
2
2
)Ph
3
11
[
15]
2
.16(3) Å similar to previously reported MICÀ Au(I) complexes.
12
3
i
13
2,6-(Pr) Ph
2,6-(Pr) Ph
2,6-(Pr) Ph
2
2
The metal centers display a slightly distorted linear geometry
and likewise as observed in complex 1, no coordination via the
oxygen atom is observed.
i
14
2
i
15
[a] Reaction conditions: Phenylacetylene (0.5 mmol), substituted aniline
0.55 mmol), catalytic system based in complex 1 (0.5 mol%)/AgSbF
During the last two decades gold(I) complexes have
demonstrated their excellent Lewis acidity for the selective
(
6
(1.0 mol%) system based in complex 2 (0.25 mol%)/AgSbF6 (0.5 mol%);
;
[17]
system based in complex 3 (0.167 mol%)/AgSbF (0.334 mol%). [b] Isolated
activation of alkenes and alkynes under mild conditions. In
particular, NHC-based gold(I) complexes have shown applic-
ability as precatalysts in various processes such as CÀ H bond
functionalizations, cyclization of enynes, hydroaminations, hy-
6
yields as the average of two runs.
[18]
drazination, cross-coupling reactions, among others. Taking
in consideration the hitherto documented enhanced catalytic
performance of multinuclear complexes compared to their
conversions to product in both cases. A decrease in reaction
time to 3 h shows higher conversions for the di- (88%) and
trinuclear complexes (96%) compared to the mononuclear
complex 1 (62%). Furthermore, the trinuclear complex 3 proved
to be the most effective precatalyst of the series converting
challenging substrates such as bulky anilines (bearing the 2,4,6-
timethyl and 2,4-diisopropylphenyl groups) into the desired
products in good yields (entries 10–15).
[11]
mononuclear analogues,
we proceeded to compare the
catalytic efficiencies of complexes 1–3 in several gold(I)-
catalyzed hydroelementation and cyclization processes.
As a first benchmark reaction, we chose the hydroamination
of terminal alkynes with aniline derivatives for which several
[19]
gold-carbene complexes have proved effective. As depicted
in Table 1, under neat conditions, the reaction between phenyl-
acetylene and aniline for 6 h proceed smoothly at low temper-
ature (40°C), using 0.5 mol% of mononuclear catalyst 1 and
The hydration of alkynes which provides the respective
ketone derivatives, is a well-known an a highly valuable reaction
in organic synthesis. In fact, several metals (mainly mercury
[
20]
salts) are known to catalyze the hydration of alkynes,
however, relatively harsh reaction conditions are usually
AgSbF (1 mol%) as halide scavenger. The reaction was also
6
[
21]
carried out using 0.25 mol% and 0.167 mol% of 2 and 3 (same
amount of gold for both complexes), respectively, providing full
required to achieve good yields.
The pivotal discovery of
[
22]
HAuCl for alkyne hydration by Utimoto and coworkers and
4
of the more effective “cationic” gold-catalyzed alkyne hydration
[23]
[24]
reactions led to the seminal findings by Nolan of highly
efficient NHC-gold complexes for the hydration of terminal and
internal alkynes. Motivated by high stability and success of
NHC-gold complexes in the hydration of alkynes, we decided to
conduct a comparative study of the catalytic performance
between the multinuclear complexes 1–3 in this process. Hence,
the hydration of phenylacetylene using the catalytic system
MICÀ Au(I)/AgSbF salt in methanol was chosen as the model
6
reaction.
As observed in Table 2, complexes 1–3 convert phenyl-
acetylene into the corresponding ketone in yields above 90%
(
entries 1–3) when the reaction is carried out at 90°C and with
catalyst loadings of 3 mol% (based in the metal). A decrease of
the temperature to 60°C results in appreciable decrease of the
yields for the mononuclear (44%) and dinuclear (69%) while,
Figure 2. Molecular structure of the of complex 2. Ellipsoids are shown at
5
0% probability. Hydrogens omitted for clarity.
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[
a]
the trinuclear complex 3 conserve its catalytic efficiency with a
conversion of 93%. The trinuclear gold complex also shows the
best performance of the series with more challenging sub-
strates including 4-methoxy-, 4-trifluoromethane- and 2,4,6-
trimetyl-substituted phenylacetylenes.
To get more insight into the catalytic behavior of the
multinuclear gold complexes 1–3, the catalytic profiles for the
hydration of phenylacetylene at 60°C were performed with the
reaction conditions presented in Table 2 (entries 1–3). As
depicted in Figure 3, complex 3 reaches conversion over 50%
after 4 h of reaction and its maximum conversion is observed in
12 h. In case of the bimetallic complex, the maximum
conversion is reached after 16 h of reaction while, the
conversion to products by complex 1 is much slower reaching
maximum conversions after 20 h and remaining unchanged
after that time.
Table 2. Hydration of phenylacetylene catalyzed by complexes 1–3.
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
Entry
Ar
[Cat]
Conversion
90°C [%]
Conversion
[b]
[b]
60° [%]
1
2
3
4
5
6
7
8
Ph
Ph
Ph
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
94
97
99
91
97
99
74
88
93
49
69
87
69
82
95
44
69
93
28
64
87
23
71
86
18
57
82
55
71
90
4-(Br)Ph
4-(Br)Ph
4-(Br)Ph
4-(OMe)Ph
4-(OMe)Ph
4-(OMe)Ph
4-(CF )Ph
4-(CF
4-(CF
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
9
10
3
1
1
1
1
2
3
3
)Ph
)Ph
3
2,4,6-(Me
2,4,6-(Me )Ph
2,4,6-(Me )Ph
3
3
)Ph
14
3
The full set of results of the catalytic profiles suggest that
1
5
[25]
the concentration of active species provided by the multi-
nuclear complex 3 has an important effect in the efficiency and
stability of the catalytic species.
[a] Reaction conditions: Phenylacetylene (1.0 mmol), water (4.0 mmol),
catalytic system based in complex 1/AgSbF (3.0 mol%, each); system
based in complex 2/AgSbF (1.5 mol%, each); system based in complex 3/
AgSbF (1.0 mol%, each); [b] Isolated yields as the average of two runs.
6
6
6
Triazolylidene-gold(I) complexes have shown to be efficient
catalysts in the synthesis of oxazolines either by the cyclization
of propargylic amides or the condensation of isocyanoacetate
[26]
and aldehydes.
As relatively few examples of oxazoline
synthesis via NHCÀ Au catalyzed processes have been reported
in the literature, we were interested in testing multinuclear gold
(I) complexes as precatalysts for the above-mentioned reaction.
Thus, the catalytic performance of complexes 1–3 was tested in
the cyclization of N-2(propyn-1-yl)benzamide to produce the
corresponding oxazoline. The reactions were performed at
room temperature with an initial complex loading of 3 mol%
(
based in the metal) and the addition of AgBF (equal mol%
4
based in the amount of gold contained in complexes 1–3) to
render catalytically active cationic Au(I) species. As observed in
Table 3, the initial conditions clearly demonstrate the enhanced
performance of the dinuclear and trinuclear complexes com-
Figure 3. Hydration of phenylacetylene using precatalysts 1–3. Reactions
1
carried out at 60°C. Conversions determined by H NMR spectroscopy based
on the amount of phenylacetylene remaining in solution using mesitylene as
internal standard.
[27]
Figure 4. Determination of reaction order in catalyst 3 by the normalized scale method.
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Conclusions
Table 3. Synthesis of substituted oxazolines using MICÀ Au complexes 1–3
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
[
a]
as precatalysts.
In summary, we have reported the convenient synthesis of a
series of mono to trinuclear gold(I) complexes bearing
phenoxy-functionalized triazolylidenes. All new compounds
have been properly characterized by NMR spectroscopy,
elemental analysis and in the case of complexes 1 and 2 by x-
ray diffraction. The catalytic performance of the new air and
moisture stable triazolylidene complexes (1–3) was tested in the
hydration and hydroamination of terminal alkynes and in the
preparation of oxazolines by the cyclization of propargylic
amines. In general, the catalytic trials established the enhanced
catalytic performance of the di- and trinuclear complexes 2 and
[b]
[b]
Entry
R
[Cat]
Conv [%] at
Conv [%] at
3[mol%] [Cat]
1[mol%] [Cat]
1
2
3
4
5
6
7
8
9
10
1
1
Ph
Ph
Ph
1
2
3
1
2
3
1
2
3
1
2
3
76
97
99
72
95
95
68
98
98
70
90
96
47
88
93
46
87
89
49
90
94
52
83
92
4-(Br)Ph
4-(Br)Ph
4-(Br)Ph
4-(OMe)Ph
4-(OMe)Ph
4-(OMe)Ph
n-hexyl
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
3
compared with the mononuclear complex 1. The increased
efficiency of complexes 2 and 3 suggest the possibility of
cooperative effects in these multinuclear complexes provided
by a higher concentration of catalytically active species. The
reaction scope and catalytic processes described in the present
study demonstrate the broad applicability of the new multi-
nuclear gold complexes. Continuous efforts related to the
exploration of the catalytic potential of complexes 1–3 is
currently being explored in our laboratory.
1
2
n-hexyl
n-hexyl
[
(
a] Reaction conditions: N-propargyl amide (1.0 mmol), dichloromethane
3 mL), room temperature, catalyst and AgBF (equal mol% based in the
4
amount of gold contained in complexes 1–3). [b] Isolated yields as the
average of two runs.
pared to the mononuclear analogue 1 (entries 1–3). Challenging
the performance of the gold precatalysts by decreasing the
complexes loading to 1 mol% (based in the metal) does not Experimental Section
affect drastically the conversion percentages of 2 and 3;
Commercially available reagents and solvents were used as
received. Triazolium salts I–III were synthesized as reported in the
however, at 1 mol% loading, complex 1 decreases its con-
version to a minimum of 47%. Furthermore, complexes 2 and 3
are highly successful in the cyclization of several propargylated
amines rendering good to excellent yields with precatalyst 3
showing a slightly better performance. The catalytic perform-
ance of complexes 2 and 3 is comparable to the recently
[10]
literature. Synthesis of all metal complexes was performed under
an atmosphere of dry nitrogen using standard Schlenk techniques.
Solvents were dried by standard methods and distilled under
nitrogen. Melting points were determined on a Fisher-Johns
apparatus and are uncorrected. NMR spectra were obtained with a
Bruker Ascend (400 MHz) spectrometer. Elemental analyses were
obtained with a Thermo Finnegan CHNSO-1112 apparatus and a
Perkin Elmer Series II CHNS/O 2400 instruments. X-Ray diffraction
analyses were collected in an Agilent Gemini Diffractometer using
Mo Kα radiation (l=0.71073 Å). Data were integrated, scaled,
sorted, and averaged using the CrysAlisPro software package. The
structures we solved using direct methods, using SHELX 2014 and
[26,27]
reported gold triazolylidene complexes.
To gain deeper insight into the enhanced catalytic perform-
ance of complex 3, we sought to explore the reaction order
with respect to the catalyst. Hence, we have performed a study
on the hydroamination of phenylacetylene with aniline using
different concentrations (0.5 mol% and 0.25 mol%) of catalyst 3
2 [29]
refined by full matrix least squares against F . All non hydrogen
and with a starting concentration of phenylacetylene of
atoms were refined anisotropically. The position of the hydrogen
atoms was kept fixed with common isotropic display parameters.
The crystallographic data and some details of the data collection
and refinement are given in Table 4.
n
1
.63 mmol. Following the normalized time scale method t[cat]
T
[28]
reported by Bures and coworkers,
the overall data is
consistent with a second order reaction with respect to the
catalyst (Figure 4). Although catalytic cooperativity in multi-
metallic metal complexes is very difficult to prove, and in most
cases, the difference in the catalytic behavior between catalysts
with a different number of metal centers is only due to subtle
differences in the steric and/or electronic properties of the
catalysts, or simply to their different thermal stabilities, the
kinetic results of the catalyst order suggest that the presence of
various metals in the same ligand exert a positive effect in the
catalytic performance, suggesting an increased local concen-
tration of active catalytic sites under homogeneous conditions.
Deposition Number 2042495 (for 1) contains the supplementary
crystallographic data for this paper. These data are provided free of
charge by the joint Cambridge Crystallographic Data Centre and
Fachinformationszentrum Karlsruhe Access Structures service
www.ccdc.cam.ac.uk/structures.
General procedure for the synthesis of gold complexes 1–3
Complex 1. Chloro(dimethylsulfide)gold (34 mg, 0.114 mmol), potas-
sium hexamethyl disylazide (30 mg, 0.149 mmol) and triazolium salt
I (50 mg, 0.115 mmol) were combined in a Schlenk flask and
dissolved in THF (9 mL) at À 78°C. The resulting mixture was stirred
for 18 h while reaching room temperature. The final clear
suspension was dried under vacuum and the residue was extracted
with benzene (10 mL). After cannula filtration and removal of the
solvent, the crude material was purified via chromatography
Eur. J. Inorg. Chem. 2021, 840–847
www.eurjic.org
844
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/ejic.202001022
Catalytic procedure for the hydroamination of
phenylacetylene using complexes 1–3
Table 4. Crystallographic Data and Summary of Data Collection and
Structure Refinement.
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
Complex 1
Typical procedure for catalytic hydroamination of alkynes: A
Schlenk flask was charged with the proper catalyst/AgSbF mixture
6
Formula
Fw
cryst syst
Space group
T, K
19 21 3
C H AuIN O
[
complex 1 (0.5 mol%)/AgSbF (1.0 mol%) complex 2 (0.25 mol%)/
6
;
631.25
Triclinic
P-1
293(2)
8.8041(9)
AgSbF6
(0.5 mol%)
or
complex 3
(0.167 mol%)/AgSbF6
(0.334 mol%)] and evacuated and filled with nitrogen three times.
Afterward, the corresponding arylamine (0.55 mmol), phenylacety-
lene (0.5 mmol) were subsequently added. The resulting mixture
was stirred at 40°C for 3 h. The final reaction mixture was filtered
through celite and the supernatant concentrated under vacuum.
The products were purified directly by column chromatography on
silica gel using appropriate mixtures of petroleum ether/diethyl
ether as eluent.
a, Å
b, Å
c, Å
α, deg
β, deg
γ, deg
11.1241(12)
11.8001(10)
112.284(9)
90.660(7)
103.686(9)
1032.39(19)
2
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
3
V, Å
Z
À 3
dcalc g.cm
2.031
8.631
À 1
μ, mm
General procedure for the hydration of alkynes catalysed by
complexes 1–3
refl collected
Tmin/Tmax
8642
0.922
4670
N
measd
To a 20 mL scintillation vial equipped with stirring bar was first
added the corresponding alkyne (1.0 mmol) followed by MeOH
[
R
int
]
0.0711
0.0554
0.1033
0.0975
0.1307
1.043
R[I>2sigma(I)]
R (all data)
R
R
(
5 mL) and water (4.0 mmol). In the case of insoluble alkynes,
CH Cl (1 mL) can be added to improve solubility. Afterward, the
2
2
w
[I>2sigma(I)]
(all data)
proper catalyst/AgSbF mixture [complex 1/AgSbF (3 mol% each);
6
6
w
complex 2/AgSbF6 (1.5 mol% each); complex 3/AgSbF6 (1.0 mol%
GOF
each)] was added and the reaction mixture was stirred at 60°C for
2
4 h. After the reaction was completed, the solvents were
evaporated. The residue was dissolved in DCM (10 mL) and the
resulting solution filtered over a short plug of silica, which was
washed with DCM (5 mL). The combined filtrates were evaporated
under reduced pressure to afford the respective ketone.
column using a mixture of dicloromethane/ethanol (95:5) provid-
ing the title product as white solid in 63% yield (45 mg,
1
0.72 mmol). m.p.=172–174°C. H NMR (400 MHz, CDCl
) δ: 7.29–
3
7
2
.23 (m, 2H, CH ), 7.02–6.94 (m, 3H, CH ), 6.89 (s, 2H, CH ), 5.32 (s,
ar ar mes
13
H, CH ), 4.22 (s, 3H, NCH ), 2.27 (s, 3H, CH ), 1.92 (s, 6H, CH ).
C
2
3
3
3
NMR (100 MHz, CDCl ) δ: 173.2 (CÀ Au), 157.0 (C ), 142.0 (C ), 140.9
3
ar
tz
General procedure for the catalytic cyclization of
propargylated amides using complexes 1–3
(
C ), 135.2 (C ), 134.3 (C ), 129.9 (CH ), 129.5 (CH ), 122.4 (CH ),
ar ar ar ar ar ar
1
15.1 (CH ), 60.1 (CH ), 38.2 (NCH ), 21.3 (CH ), 17.9 (CH ). Found: C,
ar 2 3 3 3
36.42; H, 3.56; N, 6.39; Calc for: C H AuIN O C, 36.15; H, 3.35; N,
The proper catalyst/AgBF
each);
0.34 mol% each)] and 3 mL of dry dichloromethane were charged
4
mixture [complex 1/AgBF
(0.5 mol% each);
4
(1 mol%
complex 3/AgBF4
19
21
3
6.66.
complex 2/AgBF4
(
Complex 2. According to the general procedure but using chloro
(dimethylsulfide)gold (37 mg, 0.126 mmol), potassium hexamethyl
disylazide (33 mg, 0.164 mmol), and bis-triazolium salt (50 mg,
in a 5 ml screw capped scintillation vial. After the mixture was
stirred 10 min, the proper propargylated amide was added
(
1.0 mmol) and the mixture stirred for 24 h at room temperature.
0
.063 mmol), the title product was obtained as a white solid in 81%
The solvent was removed under vacuum and the residue was
extracted with diethyl ether, washed with brine, and dried with
Na SO . The organic layer was evaporated, and the crude product
yield (60 mg, 0.051 mmol) after purification via chromatography
column using a mixture of dicloromethane/ethanol (90:10). m.p.=
2
4
1
1
7
95–197°C. H NMR (400 MHz, CDCl ) δ: 7.21 (t, J=8.2 Hz, 1H, CH ),
3
ar
was purified by silica gel column using ethyl acetate/petroleum
ether as eluent.
.08 (t, J=2.2 Hz, 1H, CH ), 6.96 (s, 4H, CH ), 6.69 (dd, J=8.2,
2.3 Hz, 2H, CH ), 5.44 (s, 4H, CH ), 4.33 (s, 6H, NCH ), 2.32 (s, 6H,
ar
mes
ar
2
3
13
CH
), 1.98 (s, 12H, CH
). C NMR (100 MHz, CDCl
) δ: 173.1 (CÀ Au),
3
3
3
1
58.4 (C ), 141.7 (C ), 140.8 (C ), 135.1 (C ), 134.3 (C ), 130.7 (CH ),
ar tz ar ar ar ar
1
29.5 (CH ), 109.7 (CH ), 101.8 (CH ), 60.3 (CH ), 38.5 (NCH ), 21.3 Acknowledgements
ar
ar
ar
2
3
(
CH ), 17.9 (CH ). Found: C, 35.11; H, 3.34; N, 7.00; Calc for:
3
3
C H Au I N O C, 32.45; H, 3.06; N, 7.10.
3
2
36
2 2
6
2
We are grateful to CONACYT (project A1-S-8892) for financial
support.
Complex 3. According to the general procedure but using chloro
dimethylsulfide)gold (38 mg, 0.130 mmol), potassium hexamethyl
disylazide (33 mg, 0.167 mmol), and bis-triazolium salt (50 mg,
.043 mmol), the title product was obtained as a white solid in 73%
(
0
Conflict of Interest
yield (54 mg, 0.031 mmol) after after purification via chromatog-
raphy column using a mixture of dicloromethane/ethanol (90:10).
1
The authors declare no conflict of interest.
m.p.=214–216°C. H NMR (400 MHz, CDCl ) δ: 6.97 (s, 6H, CHmes),
3
6
.67 (s, 3H, CH ), 5.45 (s, 6H, CH ), 4.36 (s, 9H, NCH ), 2.34 (s, 9H,
ar 2 3
13
CH ), 1.99 (s, 18H, CH ). C NMR (100 MHz, CDCl ) δ: 173.1 (CÀ Au),
3
3
3
Keywords: Triazolylidenes
· Gold · Catalysis · Alkynes ·
1
59.0 (C ), 141.5 (C ), 140.8 (C ), 135.1 (C ), 134.2 (C ), 129.4
ar tz mes mes mes
Multinuclear
(
CHmes), 96.7 (CH ), 60.1 (CH ), 38.6 (NCH ), 21.2 (CH ), 17.9 (CH ).
ar 2 3 3 3
Found: C, 31.82; H, 3.55; N, 6.98; Calc for: C H Au I N O C, 31.52;
46
54
3 3
9
3
H, 3.11; N, 7.19.
Eur. J. Inorg. Chem. 2021, 840–847
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© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/ejic.202001022
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