Mechanochemistry for facilitated access to N,N-diaryl NHC metal complexes

Article abstract of DOI:10.1039/C6NJ02895K

A user-friendly and solvent-free mechanosynthetic strategy allowed light-sensitive silver(i) complexes featuring N,N-diaryl N-heterocyclic carbenes (NHC), including challenging and sterically hindered ligands, to be yielded efficiently. The first transmet

Full text of DOI:10.1039/C6NJ02895K

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ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
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Mechanochemistry for a facilitated access to N,N-diaryl NHC
metal complexes
Received 00th January 20xx,
Accepted 00th January 20xx
a
a,
a,
a
Audrey Beillard, Xavier Bantreil, * Thomas-Xavier Métro, * Jean Martinez and Frédéric
a,
Lamaty *
DOI: 10.1039/x0xx00000x
A user-friendly and solvent-free mechanosynthetic strategy allowed to yield efficiently light-sensitive silver(I) complexes
featuring N,N-diaryl N-heterocyclic carbenes (NHC), including challenging and sterically hindered ligands. The first
transmetalations using ball-mill to obtain palladium and copper NHC complexes were performed. A convenient one-pot
www.rsc.org/
two-step
metalation/transmetalation
procedure
was
also
realized.
5
f
could not be obtained under classical solution conditions.
Introduction
Mechanochemistry and more specifically ball-milling is
becoming a more and more valuable technique for solvent-
free and environmentally friendly synthesis of organometallic
1
complexes. Among its advantages, the lowering of solvent
2
use, along with excellent agitation, generally induced
enhanced reaction rates while working without external
heating. Additionally, ball-milling provides user-friendly
procedures with simplified set-up of reactions and recovery of
products, and applications in various domains can be found in
3
literature.
Organometallic
synthesis
was
already
demonstrated to be efficient using solid-state protocols, by
grinding reagents using a mortar and pestle, giving generally
4
better and faster reactions than solution chemistry. With ball-
Scheme 1. Synthetic strategy for NHC-transition metal mechanosynthesis
milling technology, along with a more controlled and
homogeneous agitation, the same advantages were found for In this context, we recently built on our expertise in
6
the synthesis of organometallic complexes featuring a wide mechanochemistry to demonstrate that the synthesis of N,N-
5
variety of metals and ligands. As an example, solvent-free dialkyl-imidazolium salts and corresponding NHC (N-
ball-milling could supersede solution-chemistry in the heterocyclic carbene) silver complexes was extremely efficient
5
d
7
multicomponent synthesis of rhenium species. Similarly, a in a ball-mill. Moreover, the first and only mechano-
one-pot two-step mechanosynthesis of analytically pure salen- transmetalation to date yielded a NHC gold complex, which
5
c
zinc complexes was possible within only 1h milling. As a could also be obtained through a one-pot three-step
demonstration that mechanochemistry could lead to an procedure without isolating intermediates. This report was
enhanced reactivity, a relevant example is the reaction of nevertheless limited to N,N-dialkyl ligands whilst
asymmetrically substituted azobenzene with palladium(II) organometallic complexes featuring N,N-diaryl-NHC are widely
8
acetate. Like in solution, a first cyclopalladated compound described in the literature. In addition, reports involving
could be obtained, but further milling with additional Pd(OAc)2 modification or synthesis of NHC-metal complexes using
yielded quantitatively the doubly palladated complex, which grinding or ball-milling are limited. The group of Nolan
described the modification of [AuCl(NHC)] complexes into the
corresponding [Au(OR)(NHC)] complexes using a mortar and
4
h
pestle. In 2015, Adams et al. demonstrated that the synthesis
of PEPPSI-type compounds could be performed efficiently in
the ball-mill from the imidazolium salt, pyridinium precursor,
9
potassium hydroxide and the appropriate metal source. More
challenging due to their generally lower nucleophilicity and
1
higher steric hindrance, the metalation in solution of N,N-
0
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diaryl imidazolium salts in the presence of silver(I) oxide often of [AgCl(IMes)] for 10h in the vbm gave the pure complex in
required longer reaction times (24h) than their N,N-dialkyl 79% yield, and no degradation was observed.
1
1
analogues. In addition, working in refluxing solvent was
sometimes necessary. We thus wanted to assess if ball-milling
could facilitate this transformation and yield N,N-diaryl-NHC
silver complexes (Scheme 1), opening a synthetic route to
other N,N-diaryl-NHC metal complexes. It is noteworthy that in
addition to their significance as NHC transfer reagents, several
N,N-diaryl-NHCs silver complexes have shown high cytotoxicity Figure 1. Structure of the NHC used in this study
1
2
against cancer cell lines.
In all cases, before performing the work-up on the whole
reaction mixture, a sample was deposited on cotton and CDCl
3
Results and discussion
was added to quickly solubilize and filter the mixture.
1
Conversions were then calculated by H NMR. To ensure that
Classical solvent-free milling conditions, using a stainless steel
ball and jar agitated with a vibratory ball-mill (vbm) at a
frequency of 25 Hz, were firstly applied. To our delight,
the conversion measured was obtained by mixing solid
reagents together, and that the reaction was not happening
during this work-up, a control experiment was performed.
reaction
trimethylphenyl)imidazolium chloride, Figure 1) with Ag
yielded 82% of the corresponding [AgCl(IMes)] complex in only
h40 (Table 1, entry 1). As a comparison, the use of a
planetary ball-mill (pbm) at 450 rpm allowed to obtain
of
IMes
ꢀ
HCl
(1,3-bis(2,4,6-
2
IMesꢀHCl and Ag O were gently mixed together, for less than 1
2
O
min, to obtain a homogeneous mixture. A sample was directly
1
taken and the work-up described above was applied. The H
1
NMR spectra showed 0% conversion, indicating that no
reaction occurred during the work-up. In addition, the same
reaction was performed again and stopped after 15 min of
1
3
[AgCl(IMes)] in a similar manner, thus allowing to envision a
facilitated scale-up. An important feature is that silver(I)
complexes are sensitive to light and reactions in solution must
be protected from light. Stainless steel milling jars are not
transparent to light and no decomposition of the complexes
was observed, which, in addition to a short reaction time,
renders the grinding method even more user-friendly. To
support the robustness of the method, a prolonged synthesis
1
milling. H NMR spectra were recorded before and after work-
up of the whole reaction mixture. In both cases, around 30%
conversion was measured, indicating that no reaction occurred
during the treatment of the reaction using solvent.
a
Table 1. Mechanosynthesis of silver complexes
b
Entry
1
Product
%Vbur
t (h)
1.7
Yield (%)
Conditions from lit.
O (1.15 equiv.), CH Cl , 7h, reflux, 73%
O (0.65 equiv.), H O, 24h, reflux, 92%
O (0.65 equiv.), toluene, 30min, 110°C, MW, 83%
c
14
[AgCl(IMes)]
35.1
82
Ag
Ag
Ag
Ag
Ag
Ag
Ag
Ag
Ag
Ag
Ag
Ag
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
5
2
1
6
1
7
2
3
4
[AgCl(SIMes)]
[AgCl(IPr)]
34.5
42.9
44.0
1.5
3
89
89
73
O (1.5 equiv.), CH
O (0.65 equiv.), H
O (0.65 equiv.), THF, 30min, 110°C, MW, 90%
2
Cl
2
, 24h, rt, 95%
1
5
2
O, 24h, reflux, 88%
1
6
1
8
O (0.5 equiv.), CH
O (0.65 equiv.), H
O (0.65 equiv.), toluene, 30min, 110°C, MW, 85%
2
Cl
2
, 6h, reflux, 94%
15
2
O, 24h, reflux, 87%
1
6
1
7
[AgCl(SIPr)]
3
O (0.5 equiv.), CH
O (0.65 equiv.), H
O (0.65 equiv.), THF, 30min, 110°C, MW, 92%
2
Cl
2
, 24h, rt, 92%
15
2
O, 24h, reflux, 74%
1
6
Me
5
6
7
8
9
[AgCl(IMes )]
n.a.
n.a.
n.a.
44.9
n.a.
n.a.
3
3
3
3
3
3
81
86
86
82
77
89
Unprecedented
Me-cis
19
[AgCl(SIMes
)]
Ag
2
O (1.0 equiv.), CH
2
Cl
2
, 24h, 82%
Me-trans
[AgCl(SIMes
)]
Me
20
[AgCl(IPr )]
Ag
2
O (0.65 equiv.), CH
2
2
Cl , 3h, rt, 82%
Me
[AgCl(SIPr )]
Unprecedented
Unprecedented
1
0
[AgCl(TPT)]
a
b
20
c
Total mass of reactants: 182 mg, vbm = vibratory ball-mill. Data from lit. n.a. = not available. Reaction performed at 25 Hz.
2
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When
trimethylphenyl)imidazolidinium chloride) was used, milling at from literature to obtain the complexes were added to Table
5 Hz did not give reasonable conversions. However, 1. The mechanochemical method was generally found more
SIMes
ꢀ
HCl
(1,3-bis(2,4,6- yields and in short reaction times. To compare, conditions
2
increasing the frequency to 30 Hz, thus transferring more efficient than classical solution conditions, either with
energy to the reaction mixture, allowed to obtain dichloromethane or water, yielding the desired complexes in
[
AgCl(SIMes)] in 89% yield after 1h30 (Table 1, entry 2). IPr
and SIPr HCl (1,3-bis(2,6-diisopropylphenyl)-imidazolium and and no need to protect the reaction mixture from light.
imidazolidinium chlorides), which are known to be more Conditions using microwave activation were found to be faster
ꢀHCl similar yields than in literature, but in reduced reaction times
ꢀ
2
1
sterically hindered, as witnessed by the %Vbur of the ligand as the metalation occurred in 30 minutes but heating at 110°C
0
from literature data,
2
induced
a lowered reactivity. in toxic toluene or THF was necessary. The mechanochemical
Nevertheless, the milling method proved again highly efficient method is thus one of the most efficient to produce NHC silver
when a slightly prolonged reaction time of 3h was applied. complexes.
Under these conditions, [AgCl(IPr)] and [AgCl(SIPr)] were Pleased to find that the mechanosynthesis of [AgCl(NHC)]
obtained in 89% and 73% yield, respectively (Table 1, entries 3- complexes was highly practical, we questioned if
4). Having these results in hand with the most classical NHC transmetalation involving N,N-diaryl NHC could be feasible in
ligands used for organometallic synthesis, we decided to the ball-mill. In particular, transmetalation leading to gold,
extend this methodology to less common and even more copper and palladium complexes was envisioned. Indeed, such
sterically hindered NHC bearing methyl groups on the complexes are widely used in catalysis and [AuCl(IMes)] and
imidazole ring backbone. To ensure full conversion in each [CuCl(IMes)] were also reported to display higher cytotoxicity
1
2b,22
case, reaction conditions were kept at 30Hz for 3h. than cisplatin on various cancer cell lines.
Me
Gratifyingly,
Satisfyingly, [AgCl(IMes )] and its saturated congeners, mechanical agitation allowed to yield almost quantitatively
Me-cis
Me-trans
3
)] could be isolated in [AuCl(IMes)], [CuCl(IMes)] and [PdCl(η -allyl)(IMes)] starting
[AgCl(SIMes
)] and [AgCl(SIMes
8
1-86% yield (Table 1, entries 5-7). It is important to note that from [AgCl(IMes)] in only 1h to 1.5h of reaction, using a
Me-cis
Me-trans
the two isomers, SIMes
ꢀ
HCl and SIMes
ꢀHCl, were stainless steel ball and jar agitated with a vbm at a frequency
separated during their synthesis, characterized and assigned of 25 Hz (Scheme 2). Importantly, the last two examples
thanks to X-Ray diffraction of the trans isomer (Figure 2). To represent the first transmetalations in the ball-mill leading to
the best of our knowledge, it is the first time that they were copper and palladium complexes. Conditions for the synthesis
reacted separately to furnish the two diastereomeric silver(I) of the gold complex were directly applied from our previous
7
report involving N,N-dialkyl NHC ligands. A rapid optimization
complexes.
of the stoichiometry and reaction time allowed to reach full
1
conversion, as confirmed by H NMR, when copper and
palladium reagents were used in slight excess.
Me-trans
Figure 2. ORTEPs (probability at 50% level) of SIMes
. H and Cl atoms are omitted
for clarity.
Me
Me
Similarly, [AgCl(IPr )] and unprecedented [AgCl(SIPr )],
which was obtained as a mixture of isomers, could be
produced in 82% and 77% yield, respectively (Table 1, entries
8-9). Finally, the methodology was also extended to the
triazolium salt TPTꢀHCl (1,3,4-triphenyl-1,2,4-triazolium
chloride, Figure 1), which was converted to the corresponding Scheme 2. Transmetalation of [AgCl(IMes)] using mechanochemistry
silver complex in 89% yield (Table 1, entry 10). The
In order to increase the usefulness of this methodology, we
attempted to perform both metalation and transmetalation in
mechanochemical method appeared to be quite general and
allowed to access previously described as well as
unprecedented NHC-silver(I) complexes in good to excellent
a one-pot two-step process, starting directly from IMesꢀHCl
without isolating the [AgCl(IMes)] intermediate (Scheme 3).
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Using this procedure, both the use of a solvent for isolating the All of reactions mixture were recovered with a solvent and
intermediate and the silver complexes light exposure issue filtrated over celite to remove metallic particles lost by the
could be avoided. Satisfyingly, this one-pot two-step strategy reactor during ball milling.
allowed the isolation of [AuCl(IMes)] in 76% yield, in solely All of the reactions using vibratory ball mill were made at 25
2
h40 reaction in the ball-mill. Similarly, [CuCl(IMes)] and Hz or 30 Hz under air with no interruption of the milling.
3
PdCl(η -allyl)(IMes)] could be synthesized in higher yield than Syntheses
[
with the procedure involving isolation of the intermediate
silver complex (90% and 92% yield vs 81% and 80% yield,
respectively).
General procedure for the synthesis of [AgCl(IMes)] in a vbm
1,3-Bis-(2,4,6-trimethylphenyl)imidazolium chloride (132.4 mg,
0.389 mmol, 1.00 eq) and silver oxide (49.5 mg, 0.214 mmol,
0.55 eq) were introduced in a 10 mL stainless steel grinding
bowl with one stainless steel ball (10 mm diameter). Total
mass of the reagents was calculated so that milling load equals
1
9.2 mg/mL. The bowl was closed and subjected to grinding
for 1 hour and 40 minutes in the vibratory ball mill operated at
5 Hz. The grey powder was recovered with dichloromethane
2
and the suspension was filtrated over celite. The filtrate was
concentrated under vacuum to afford [1,3-bismesitylimidazol-
2
-ylidene]silver chloride (142.3 mg, 0.318 mmol, 82%) as a pale
brown solid.
Synthesis of [AgCl(IMes)] in a pbm
Scheme 3. One-pot two-step synthesis of organometallic complexes from 1,3-Bis-(2,4,6-trimethylphenyl)imidazolium chloride (122.0 mg,
IMesꢀHCl
0
.358 mmol, 1.00 eq) and silver oxide (45.6 mg, 0.197 mmol,
.55 eq) were introduced in a 12 mL stainless steel grinding
0
bowl with fifty stainless steel balls (5 mm diameter). Total
mass of the reagents was calculated so that milling load equals
Conclusion
1
9.2 mg/mL. The bowl was closed and subjected to grinding
In conclusion, silver complexes featuring N,N-diaryl N-
heterocyclic carbenes could be obtained in less than 3h at
room temperature under solvent-free ball-milling. This user-
friendly and highly efficient method allowed the
transmetalation with copper, gold and palladium, without
observable decomposition of the silver complex. Ultimately, a
highly practical one-pot two-step metalation/transmetalation
procedure allowed to yield directly copper, gold and palladium
complexes, in short reaction times and without isolation of the
silver intermediates.
for 2 hours in the planetory ball mill operated at 450 rpm. The
grey powder was recovered with dichloromethane and the
suspension was filtrated over celite. The filtrate was
concentrated under vacuum to afford [1,3-bismesitylimidazol-
2
-ylidene]silver chloride (140.3 mg, 0.313 mmol, 88%) as a pale
brown solid.
1
[
3
AgCl(IMes)]. H NMR (300 MHz, CDCl ) δ 7.14 (d, J = 1.5 Hz,
1
3
2
H), 7.00 (s, 4H), 2.36 (s, 6H), 2.08 (s, 12H); C NMR (101 MHz,
δ 183.1 (dd, J = 256.0, 18.3 Hz), 139.9, 135.3, 134.7,
CDCl
3
)
2
3
1
29.7, 122.9, 122.8, 21.2, 17.8. Data in agreement with lit.
1
AgCl(SIMes)]. White solid, 69% yield. H NMR (400 MHz,
[
1
3
Experimental
CDCl
3
)
δ 6.96 (s, 4H), 4.01 (s, 4H), 2.31 (s, 6H), 2.30 (s, 12H);
C
NMR (101 MHz, CDCl
1.2, 51.1, 21.0, 17.9. Data in agreement with lit.
AgCl(IPr)]. White powder, 89% yield. A mixture of [AgCl(IPr)]
and [Ag(IPr) ]Cl were obtained in 95:5 ratio. Peaks for
AgCl(IPr)] (major product) are reported: H NMR (400 MHz,
CDCl δ 7.50 (t, J = 7.8 Hz, 2H), 7.30 (d, J = 7.8 Hz, 4H), 7.22 (d,
J = 1.8 Hz, 2H), 2.62 – 2.47 (m, 4H), 1.28 (d, J = 6.9 Hz, 12H),
3
)
δ 164.2, 138.9, 135.4, 135.1, 129.9,
General remarks
2
3
5
All reagents were purchased from Aldrich Chemical Co., Fluka
and Alfa Aesar and used without further purification. The
milling treatments were carried out either in a vibrating Retsch
Mixer Mill 200 (vbm) or in a Retsch PM100 Planetary Mill
[
2
1
[
3
)
(
pbm). Milling load is defined as the sum of the mass of the
1
1
3
reactants per free volume in the jar. H NMR spectra were
recorded on a Bruker Avance DPX 300 MHz, 400 MHz or
Bruker Avance III 600 MHz spectrometer and are reported in
1.22 (d, J = 6.9 Hz, 12H); C NMR (101 MHz, CDCl
3
) δ 184.6
(
dd, J = 258.5, 21.4 Hz), 145.7, 134.6, 130.9, 124.5, 123.8,
2
3
1
23.7, 28.8, 24.8, 24.1. Data in agreement with lit.
1
ppm using deuterated solvent used for calibration (CDCl at
3
[AgCl(SIPr)]. White solid, 73% yield. H NMR (400 MHz, CDCl3)
δ 7.42 (t, J = 7.8 Hz, 2H), 7.24 (d, J = 7.8 Hz, 4H), 4.06 (s, 4H),
7.26 ppm or DMSO-d at 2.50 ppm). Data are reported as s =
6
singlet, d = doublet, t = triplet, q = quadruplet, qt = quintuplet,
m = multiplet, sept = septuplet; coupling constant in Hz;
3
.05 (hept, J = 6.9 Hz, 4H), 1.342 (d, J = 6.9 Hz, 12H), 1.337 (d, J
1
3
13
=
3
6.9 Hz, 12H); C NMR (101 MHz, CDCl ) δ C of carbene was
1
3
integration. C NMR spectra were recorded on Bruker Avance
AM 75 MHz or 101 MHz spectrometers and are reported in
not observed, 146.7, 134.6, 130.2, 124.9, 54.1, 54.0, 29.0, 25.6,
3
2
2
4.2. Data in agreement with lit.
Me
ppm using deuterated solvent used for calibration (CDCl at
3
[AgCl(IMes )]. Pale brown solid, 81% yield. A mixture of
Me
Me
77.2 ppm or DMSO-d6 at 39.5 ppm). HRMS analysis was
2
[AgCl(IMes )] and [Ag(IMes ) ]Cl were obtained in 90:10
performed on a Q-Tof (Waters, ESI, 2001) spectrometer.
4
| J. Name., 2012, 00, 1-3
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ARTICLE
Me
ratio. Peaks for [AgCl(IMes )] (major product) are reported: The white powder was recovered with dichloromethane and
1
H NMR (300 MHz, CDCl
3
)
δ 6.99 (s, 4H), 2.35 (s, 6H), 2.01 (s, the suspension was filtrated over celite. The filtrate was
2H), 1.91 (s, 6H); C NMR (101 MHz, CDCl δ 178.8 (dd, J = concentrated under vacuum to afford [1,3-bismesitylimidazol-
58.4, 18.4 Hz), 139.5, 135.0, 134.0, 129.7, 126.13, 126.07, 2-ylidene]copper chloride (122.7 mg, 0.304 mmol, 100%) as a
1
3
1
2
2
3
)
-
+
1.2, 17.8, 9.3. HRMS calcd for C23
H
28
N
2
Ag [M–Cl ] : 439.1303; white powder.
One-pot two-step preparation of [CuCl(IMes)] from IMes
)]. White solid, 86% yield. H NMR (300 MHz, 1,3-bis-(2,4,6-trimethylphenyl)imidazolium chloride (100.6 mg,
δ 6.96 (s, 2H), 6.94 (s, 2H), 4.47 (s, 2H), 2.36 (s, 6H), 2.30 0.295 mmol, 1.00 eq) and silver oxide (37.6 mg, 0.162 mmol,
found: 439.1308.
ꢀHCl
Me-cis
1
[AgCl(SIMes
CDCl
3
)
1
3
(s, 6H), 2.27 (s, 6H), 1.19 (d, J = 5.5 Hz, 6H); C NMR (101 MHz, 0.55 eq) were introduced in a 10 mL stainless steel grinding
CDCl
3
)
δ 206.1 (dd, J = 242.4, 17.4 Hz), 138.5, 136.3, 135.5, bowl with one stainless steel ball (10 mm diameter). The bowl
1
34.1, 130.1, 130.0, 61.4, 61.3, 21.0, 19.1, 18.1, 13.0; HRMS was closed and subjected to grinding for 1 hour and 40
+
calcd for C46
H
60
Me-trans
N
4
Ag [M – Cl] : 775.3869; found: 775.3879.
minutes in the vibratory ball mill operated at 25 Hz. The bowls
)]. White solid, 86% yield. H NMR (400 was open and copper(I) chloride (43.8 mg, 0.442 mmol, 1.50
δ 6.94 (s, 2H), 6.91 (s, 34H), 4.07 – 3.91 (m, 2H), eq) was added. Total mass of the reagents was calculated so
.32 (s, 6H), 2.28 (s, 6H), 2.26 (s, 6H), 1.28 (d, J = 5.8 Hz, 6H); that milling load equals 19.2 mg/mL. The bowl was closed and
1
[
AgCl(SIMes
MHz, CDCl
3
)
2
1
3
C NMR (101 MHz, CDCl
3
) δ 207.64 (dd, J = 242.0, 17.4 Hz), subjected to grinding for 1 hour in the vibratory ball mill
1
1
7
38.6, 136.6, 135.3, 134.0, 130.1, 130.0, 66.64, 66.54, 21.0, operated at 25 Hz. The grey powder was recovered with
+
9.1, 18.4, 18.0; HRMS calcd for C46
H
60
N
4
Ag [M – Cl] : dichloromethane and the suspension was filtrated over celite.
The filtrate was concentrated under vacuum to afford [1,3-
75.3869; found: 775.3870.
Me
[
AgCl(IPr )]. Pale brown solid, 82% yield. After purification, a bismesitylimidazol-2-ylidene]copper chloride (107.2 mg, 0.266
Me
mixture of [AgCl(IPr )] and [Ag(IPr
Me
2
) ]Cl was obtained in 97:3 mmol, 90%) as a white powder.
Me
1
1
ratio. Peaks for [AgCl(IPr )] (major product) are reported:
NMR (400 MHz, DMSO-d δ 7.60 – 7.53 (m, 2H), 7.44 (d, J = 6H), 2.11 (s, 12H); C NMR (75 MHz, CDCl3) δ 179.9, 139.6,
.7 Hz, 4H), 2.39 (sept, J = 6.8 Hz, 4H), 1.95 (s, 6H), 1.22 (d, J = 135.5, 134.5, 129.6, 129.2, 122.6, 121.9, 21.2, 17.8. Data in
H
3
H NMR (300 MHz, CDCl ) δ 7.07 (s, 2H), 7.01 (s, 4H), 2.36 (s,
1
3
6
)
7
6
1
3
24
.8 Hz, 12H), 1.18 (d, J = 6.8 Hz, 12H); C NMR (101 MHz, agreement with lit.
δ 178.9 (dd, J = 253.1, 18.1 Hz), 146.0, 133.2, 131.1,
27.3, 127.2, 124.9, 28.6, 25.5, 23.4, 9.6. Data in agreement Preparation of [AuCl(IMes)] from [AgCl(IMes)]
6
DMSO-d )
1
2
0
with lit.
[1,3-Bismesitylimidazol-2-ylidene]silver chloride (101.7 mg,
Me
[AgCl(SIPr )]. White solid, 77% yield. Mixture of 0.227 mmol, 1.00 eq) and chloro(dimethylsulfide)gold (80.3
1
diastereoisomers (57:43) H NMR (400 MHz, DMSO-d
6
)
δ 7.46 mg, 0.273 mmol, 1.20 eq) were introduced in a 10 mL stainless
t, J = 7.7 Hz, 2H), 7.36 (t, J = 6.7 Hz, 4H), 4.57 (s, 2H, 43%), 4.01 steel grinding bowl with one stainless steel ball (10 mm
s, 2H, 57%), 3.26 (sept, J = 6.8 Hz, 2H, 57%), 3.15 (sept, J = 6.9 diameter). Total mass of the reagents was calculated so that
(
(
Hz, 2H, 43%), 3.06 (sept, J = 6.9 Hz, 2H, 43%), 2.95 (sept, J = 6.8 milling load equals 19.2 mg/mL. The bowl was closed and
Hz, 2H, 57%), 1.35 – 1.26 (m, 18H), 1.23 (d, J = 6.7 Hz, 12H, subjected to grinding for 1 hour in the vibratory ball mill
5
7%), 1.19 (d, J = 6.7 Hz, 6H, 43%), 1.14 (d, J = 4.8 Hz, 6H, 43%); operated at 25 Hz. The yellow powder was recovered with
13
Major diastereoisomer: C NMR (101 MHz, DMSO-d
6
)
δ 206.3 dichloromethane and the suspension was filtrated over silica.
(dd, J = 201.0, 17.2 Hz), 147.5, 146.8, 132.9, 129.8, 124.7, The filtrate was concentrated under vacuum to afford [1,3-
1
24.4, 68.3, 68.2, 28.2, 28.1, 25.9, 25.1, 23.6, 22.8, 17.4; Minor bismesitylimidazol-2-ylidene]gold chloride (117.5 mg, 0.219
13
diastereoisomer: C NMR (101 MHz, DMSO-d
6
)
δ 203.9 (dd, J mmol, 96%) as pale yellow powder.
201.2, 17.8 Hz), 147.4, 146.8, 133.2, 129.6, 124.5, 63.0, 62.9, One-pot two-step preparation of [AuCl(IMes)] from IMes
=
2
ꢀHCl
8.3, 28.0, 25.9, 25.2, 23.4, 23.1, 12.8; HRMS calcd for
+
Ag [M – Cl] : 525.2399; found: 525.2404.
1
,3-Bis-(2,4,6-trimethylphenyl)imidazolium chloride (75.5 mg,
.221 mmol, 1.00) and silver oxide (28.2 mg, 0.122 mmol, 0.55
C
29
H
42
N
2
0
[
AgCl(TPT)]. Brown crystallized powder, 89% yield.
eq) were introduced in a 10 mL stainless steel grinding bowl
with one stainless steel ball (10 mm diameter). The bowl was
closed and subjected to grinding for 1 hour and 40 minutes in
the vibratory ball mill operated at 25 Hz. Afterwards,
chloro(dimethylsulfide)gold (78.3 mg, 0.266 mmol, 1.20 eq)
were added. Total mass of the reagents was calculated so that
milling load equals 19.2 mg/mL. The bowl was closed and
subjected to grinding for 1 hour and 30 minutes in the
1
H NMR (400 MHz, DMSO-d
6
) δ 8.08 – 8.00 (m, 2H), 7.64 –
1
.48 (m, 9H), 7.46 – 7.41 (m, 4H); C NMR (151 MHz, DMSO-
3
7
d
6
)
δ 183.5, 154.1, 139.5, 137.0, 131.6, 130.6, 130.3, 130.0,
1
15 3
29.6, 129.2, 127.5, 124.7, 123.3; HRMS calcd for C20H N Ag
+
M – Cl] : 404.0317; found: 404.0317.
[
Preparation of [CuCl(IMes)] from [AgCl(IMes)]
[1,3-Bismesitylimidazol-2-ylidene]silver chloride (136.6 mg, vibratory ball mill operated at 25 Hz. The grey powder was
0
.305 mmol, 1.00 eq) and copper(I) chloride (45.3 mg, 0.458 recovered with dichloromethane and the suspension was
mmol, 1.50 eq) were introduced in a 10 mL stainless steel filtrated over silica. The filtrate was concentrated under
grinding bowl with one stainless steel ball (10 mm diameter). vacuum to afford [1,3-bismesitylimidazol-2-ylidene]gold
1
Total mass of the reagents was calculated so that milling load chloride (90.2 mg, 0.168 mmol, 76%) as a pale yellow solid.
equals 19.2 mg/mL. The bowl was closed and subjected to NMR (600 MHz, CDCl3) δ 7.10 (s, 1H), 6.99 (s, 2H), 2.35 (s, 3H),
H
grinding for 1 hour in the vibratory ball mill operated at 25 Hz.
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ARTICLE
Journal Name
1
3
2
3
.11 (s, 6H); C NMR (151 MHz, CDCl )
δ 173.5, 139.8, 134.71, 3. (a) D. Braga and F. Grepioni, Angew. Chem. Int. Ed., 2004, 43,
2
5
4
2
002; (b) A. L. Garay, A. Pichon and S. L. James, Chem. Soc. Rev.,
007, 36, 846; (c) S. L. James, C. J. Adams, C. Bolm, D. Braga, P.
1
34.68, 129.5, 122.4, 21.2, 17.8. Data in agreement with lit.
3
Collier, T. Friščić, F. Grepioni, K. D. M. Harris, G. Hyett, W. Jones, A.
Krebs, J. Mack, L. Maini, A. G. Orpen, I. P. Parkin, W. C. Shearouse, J.
W. Steed and D. C. Waddell, Chem. Soc. Rev., 2012, 41, 413; (d) A.
Stolle, B. Ondruschka, A. Krebs and C. Bolm, in Innovative Catalysis
in Organic Synthesis, Wiley-VCH Verlag GmbH & Co. KGaA, 2012,
Preparation of [PdCl(η -allyl)(IMes)] from [AgCl(IMes)]
[
1,3-Bismesitylimidazol-2-ylidene]silver chloride (118.8 mg,
.265 mmol, 1.00 eq) and allylpalladium chloride dimer (63.1
mg, 0.173 mmol, 0.65 eq) were introduced in a 10 mL stainless
0
steel grinding bowl with one stainless steel ball (10 mm pp. 327-349; (e) E. Boldyreva, Chem. Soc. Rev., 2013, 42, 7719; (f) D.
diameter). Total mass of the reagents was calculated so that Braga, L. Maini and F. Grepioni, Chem. Soc. Rev., 2013, 42, 7638; (g)
milling load equals 19.2 mg/mL. The bowl was closed and K. Ralphs, C. Hardacre and S. L. James, Chem. Soc. Rev., 2013, 42,
subjected to grinding for 1 hour and 30 minutes in the 7701; (h) L. Takacs, Chem. Soc. Rev., 2013, 42, 7649; (i) G.-W. Wang,
Chem. Soc. Rev., 2013, 42, 7668; (j) S.-E. Zhu, F. Li and G.-W. Wang,
Chem. Soc. Rev., 2013, 42, 7535; (k) J. G. Hernández and T. Friščić,
Tetrahedron Lett., 2015, 56, 4253; (l) T. Friščić, D. Tan and L. Loots,
Chem. Commun., 2016, 52, 7760.
vibratory ball mill operated at 25 Hz. The black powder was
recovered with dichloromethane and the suspension was
filtrated over celite. The filtrate was concentrated under
vacuum and the resulting solid was put on silica, filtrated with
4
2
.
(a) P. J. Nichols, C. L. Raston and J. W. Steed, Chem. Commun.,
cyclohexane to remove excesses of allylpalladium chloride
dimer and ethyl acetate to collect the desired product. Ethyl
001, 1062; (b) W. J. Belcher, C. A. Longstaff, M. R. Neckenig and J.
W. Steed, Chem. Commun., 2002, 1602; (c) D. Braga, L. Maini, M.
acetate was evaporated to afford [1,3-bismesitylimidazol-2-
3
Polito and F. Grepioni, Chem. Commun., 2002, 2302; (d) A. Orita, L.
ylidene](η -2-propen-1-yl)palladium chloride (122.0 mg, 0.250 Jiang, T. Nakano, N. Ma and J. Otera, Chem. Commun., 2002, 1362;
mmol, 94%) as pale yellow powder.
One-pot two-step preparation of [PdCl(η -allyl)(IMes)] from
IMes HCl
(e) C. J. Adams, H. M. Colquhoun, P. C. Crawford, M. Lusi and A. G.
Orpen, Angew. Chem. Int. Ed., 2007, 46, 1124; (f) C. J. Adams, M. A.
Kurawa, M. Lusi and A. G. Orpen, CrystEngComm, 2008, 10, 1790;
3
ꢀ
(
g) D. Braga, F. Grepioni, L. Maini, R. Brescello and L. Cotarca,
1
,3-Bis-(2,4,6-trimethylphenyl)imidazolium chloride (87.8 mg,
.258 mmol, 1.00) and silver oxide (32.8 mg, 0.142 mmol, 0.55
CrystEngComm, 2008, 10, 469; (h) J. D. Egbert, A. M. Z. Slawin and S.
P. Nolan, Organometallics, 2013, 32, 2271.
5
Chem. Commun., 2002, 1606; (b) C. J. Adams, M. F. Haddow, R. J. I.
Hughes, M. A. Kurawa and A. G. Orpen, Dalton Trans., 2010, 39,
3
0
eq) were introduced in a 10 mL stainless steel grinding bowl
with one stainless steel ball (10 mm diameter). The bowl was
closed and subjected to grinding for 1 hour and 40 minutes in
the vibratory ball mill operated at 25 Hz. Afterwards,
. (a) V. P. Balema, J. W. Wiench, M. Pruski and V. K. Pecharsky,
714; (c) M. Ferguson, N. Giri, X. Huang, D. Apperley and S. L.
allylpalladium chloride dimer (61.3 mg, 0.167 mmol, 0.65 eq) James, Green Chem., 2014, 16, 1374; (d) J. G. Hernández, I. S. Butler
were added. Total mass of the reagents was calculated so that and T. Friščić, Chem. Sci., 2014, 5, 3576; (e) M. Juribašić, I. Halasz, D.
milling load equals 19.2 mg/mL. The bowl was closed and Babić, D. Cinčić, J. Plavec and M. Ćurić, Organometallics, 2014, 33,
1
227; (f) M. Juribašić, K. Užarević, D. Gracin and M. Ćurić, Chem.
subjected to grinding for 1 hour and 30 minutes in the
vibratory ball mill operated at 25 Hz. The black powder was
recovered with dichloromethane and the suspension was
filtrated over celite. The filtrate was concentrated under
vacuum and the resulting solid was put on silica, filtrated with
cyclohexane to remove excesses of allylpalladium chloride
dimer and ethyl acetate to collect the desired product. Ethyl
Commun., 2014, 50, 10287; (g) J. G. Hernández and C. Bolm, Chem.
Commun., 2015, 51, 12582; (h) J. Wang, R. Ganguly, L. Yongxin, J.
Diaz, H. S. Soo and F. Garcia, Dalton Trans., 2016, 45, 7941.
6
. (a) V. Declerck, P. Nun, J. Martinez and F. Lamaty, Angew.
Chem. Int. Ed., 2009, 48, 9318; (b) V. Declerck, E. Colacino, X.
Bantreil, J. Martinez and F. Lamaty, Chem. Commun., 2012, 48,
1
1778; (c) J. Bonnamour, T.-X. Métro, J. Martinez and F. Lamaty,
acetate was evaporated to afford [1,3-bismesitylimidazol-2-
3
Green Chem., 2013, 15, 1116; (d) T.-X. Métro, J. Bonnamour, T.
ylidene](η -2-propen-1-yl)palladium chloride (110.8 mg, 0.227 Reidon, A. Duprez, J. Sarpoulet, J. Martinez and F. Lamaty, Chem.
mmol, 88%) as a pale yellow solid.
1
Eur. J., 2015, 21, 12787; (e) T.-X. Métro, X. J. Salom-Roig, M.
δ 7.09 (s, 2H), 6.97 (s, 4H), 4.93 – Reverte, J. Martinez and F. Lamaty, Green Chem., 2015, 17, 204; (f)
H NMR (400 MHz, CDCl )
3
A. Beillard, X. Bantreil, T.-X. Métro, J. Martinez and F. Lamaty,
Dalton Trans., 2016, 45, 17859.
4
.77 (m, 1H), 3.94 – 3.83 (m, 1H), 3.39 (d, J = 6.1 Hz, 1H, 25%),
.20 (d, J = 6.1 Hz, 1H, 75%), 2.81 (d, J = 13.5 Hz, 1H, 75%), 2.76
3
7
.
A. Beillard, E. Golliard, V. Gillet, X. Bantreil, T.-X. Métro, J.
(d, J = 13.4 Hz, 1H, 25%), 2.33 (s, 6H), 2.23 (s, 6H), 2.20 (s, 6H),
Martinez and F. Lamaty, Chem. Eur. J., 2015, 21, 17614.
1
.87 (d, J = 12.1 Hz, 1H, 25%), 1.80 (d, J = 11.8 Hz, 1H, 75%);
8
8
9
.
S. Díez-González and S. P. Nolan, Coord. Chem. Rev., 2007, 251,
74.
C. J. Adams, M. Lusi, E. M. Mutambi and A. G. Orpen, Chem.
1
Major diastereoisomer: C NMR (101 MHz, CDCl
3
3
)
δ 183.8,
1
2
39.0, 136.0, 135.6, 129.2, 129.1, 123.1, 114.4, 72.5, 49.3,
1
.
3
1.3, 18.43, 18.37; Minor diastereoisomer: C NMR (101 MHz,
δ 183.3, 139.0, 136.0, 135.5, 129.3, 129.2, 123.2, 113.9,
Commun., 2015, 51, 9632.
0. D. G. Gusev, Organometallics, 2009, 28, 6458.
CDCl
3
)
1
2
6
71.7, 52.5, 21.3, 18.71, 18.66. Data in agreement with lit.
11. J. C. Y. Lin, R. T. W. Huang, C. S. Lee, A. Bhattacharyya, W. S.
Hwang and I. J. B. Lin, Chem. Rev., 2009, 109, 3561.
1
2. (a) K. M. Hindi, M. J. Panzner, C. A. Tessier, C. L. Cannon and W.
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J. Youngs, Chem. Rev., 2009, 109, 3859; (b) M.-L. Teyssot, A.-S.
Jarrousse, M. Manin, A. Chevry, S. Roche, F. Norre, C. Beaudoin, L.
Morel, D. Boyer, R. Mahiou and A. Gautier, Dalton Trans., 2009,
1.
.
N. R. Rightmire and T. P. Hanusa, Dalton Trans., 2016, 45, 2352.
G. A. Bowmaker, Chem. Commun., 2013, 49, 334.
2
6
894.
6
| J. Name., 2012, 00, 1-3
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NP lee wa s eJ od uo r nn oa tl aod fj uC s ht em ma ri sg it nr ys
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Journal Name
ARTICLE
1
1
3. See Supporting Information for details
4. T. Ramnial, C. D. Abernethy, M. D. Spicer, I. D. McKenzie, I. D.
Gay and J. A. C. Clyburne, Inorg. Chem., 2003, 42, 1391.
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Cazin, Dalton Trans., 2010, 39, 4489.
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Table of content
A solvent-free synthesis of NHC-silver, gold, copper and palladium complexes was
achieved in a ball-mill.