Copper-induced ammonia N-H functionalization

Article abstract of DOI:10.1039/c5dt04972e

The activation of ammonia has been achieved with the aid of the Tp^MsCu core (Tp^Ms = hydrotris(3-mesityl-pyrazolyl)borate). Complexes of the general composition Tp^MsCu(amine) (1-4) including the ammonia adduct Tp^MsCu(NH₃) (1) have been synthesized and fully spectroscopical- and structurally characterized. Coordinated ammonia in 1 has been reacted with Ph₃CPF₆ yielding Tp^MsCu(NH₂CPh₃) (5) as a result of N-H cleavage and N-C bond formation. In a parallel manner the catalytic functionalization of ammonia with ethyl diazoacetate leading to glycinate derivatives has been developed with Tp^MsCu(THF) as the catalyst, in the first example of this transformation with ammonia and a copper-based system.

Full text of DOI:10.1039/c5dt04972e

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ARTICLE
Copper-Induced Ammonia N-H Functionalization
§
≠
§
§
María Álvarez, Eleuterio Álvarez, Manuel R. Fructos, Juan Urbano and Pedro J. Pérez *
Received 00th January 20xx,
Accepted 00th January 20xx
Ms
Ms
The activation of ammonia has been achieved with the aid of the Tp Cu core (Tp = hydrotris(3-mesytil-pyrazolyl)borate)
Ms
Ms
3
Complexes of general composition Tp Cu(amine) (1-4) including the ammonia adduct Tp Cu(NH ) (1) have been
DOI: 10.1039/x0xx00000x
synthesized and fully spectroscopic- and structurally characterized. Coordinated ammonia in 1 has been reacted with
Ms
www.rsc.org/
3 6 2 3
Ph CPF yielding Tp Cu(NH CPh ) (5) as the result of N-H cleavage and N-C bond formation. In a parallel manner the
catalytic functionalization of ammonia with ethyl diazoacetate leading to glycinate derivatives has been developed with
Ms
Tp Cu(THF) as the catalyst, in the first example of this transformation with
a copper-based system.
reactivity of the N-H bonds, from which we have observed N-H
bond cleavage and subsequent N-C bond formation in a process
Introduction
The activation of the N-H bonds of ammonia yet constitutes a
challenge for current chemistry, particularly in the context of metal-
that provides a net NH
manner, the catalytic functionalization of ammonia upon insertion
of CHCO Et carbene units (from ethyl diazoacetate, N CHCO Et,
3
functionalization. Additionally, in a parallel
1
catalysed (hydro)amination reactions. Ammonia can coordinate a
2
2
2
number of transition metals, and subsequent reactivity may lead to
amido, imido (nitrene) and even nitrido complexes, that could serve
Ms
EDA) has been achieved employing Tp Cu(THF) as the catalyst. The
9
latter has only been described to date with iron-based catalysts,
2
,3
as intermediates in catalytic cycles. During the last decade a
the current work constituting, to the best of our knowledge, the
first example of a copper-catalysed ammonia functionalization with
this strategy, since previous examples with this metal being were
x
x
family of tetracoordinate complexes bearing the Tp Cu moiety (Tp
=
hydrotrispyrazolylborate ligand) and a fourth donor ligand such as
4
5
6
7
8
CH
3
CN, CO, PR
3
alkene or alkyne has been developed (Scheme
10
described only with substituted amines. .
Ms
1). The use of Tp [hydrotris(3-mesitylpyrazolyl)borate] provided
interesting features to those complexes due to the interaction
Results and Discussion
between the aryl rings with olefin/alkyne ligands. Interestingly, we
x
Ms
found that in spite of the large number of Tp CuL complexes Synthesis and characterization of Tp Cu(NH
3
) (1).
reported to date, the ammonia derivative remained yet
Ms
The ammonia adduct Tp Cu(NH ) (1) has been synthesized
3
undescribed. With this idea in mind, we started this work that has
Ms
using Tp Cu(THF) as the starting material, following a
Ms
led to the synthesis and structural characterization of Tp Cu(NH
3
),
x
procedure already described for other olefin or alkyne Tp -
Ms
as well as a series of related Tp Cu(NR
3
) for comparative purposes.
7,8
copper adducts in our group (eqn (1)). Ammonia gas was
The availability of the ammonia adduct has allowed the study of the
Ms
bubbled through a colourless solution of Tp Cu(THF) in
dichloromethane for 15-20 min, and the solution was then
stored in the freezer at -30 ºC from which colourless crystalline
material was collected in 95% isolated yield after three
successive crops. The formulation of this compound as
Ms
3
Tp Cu(NH ) (1) came straightforwardly from its spectroscopic
1
and analytical data. For instance, the H NMR spectrum
H
B
H
B
N
N
N
N
N
N
N
N
N
N
N
N
NH3(g), rt
CH Cl
(
1)
Cu
O
Cu
N
2
2
-THF
1
H
H
H
x
Scheme 1. Previously described Tp CuL complexes.
Ms
showed the typical resonances of the coordinated Tp ligand
with one signal for each independent nucleus of the pyrazolyl
moiety, as the result of a local C3v symmetry that makes the
§
Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro de
Investigación en Química Sostenible and Departamento de Química , Universidad
de Huelva, Campus de El Carmen 21007 Huelva, Spain.
≠
Instituto de Investigaciones Químicas, Centro de Investigaciones Isla de la Cartuja,
Avda Américo Vespucio 49,41092 Sevilla, Spain.
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three pyrazolyl rings equivalents. In addition, a broad singlet mixtures (see Experimental Section). These new copper-amine
located at δ 0.59 ppm that integrated for 3H has been assigned adducts are stable under vacuum in the solid state and even
to coordinated NH
absorption at 3374 cm attributable to
first row transition metal ammonia complexes.
3
. The IR spectrum displayed a broad under air for short periods of time. Their spectroscopic and
-1
ν
(N-H) typical for the analytical data were in agreement with their formulation as
1
1
Ms
the amine adduct of the Tp Cu moiety.
x
Interestingly, attempts to isolate other Tp Cu(NH
3
) complexes X-ray studies carried out with complexes 2-4 have shown in all
Ms
x
using Tp ligands (Tp = Tp* or Tp ) different from Tp have cases a distorted tetrahedral geometry around the copper
x
Br3
failed. It seems that the steric protection provided by the centre. Figure 2 shows the ORTEP view of the molecules of
mesytil substitutent is crucial for the stability of the ammonia a representative example (see ESI for those of complexes
and
angles for complexes
averaged 2.073 Å in , 2.08 Å in
These values are slightly shorter than those found in the olefin
4
as
2
3
). Table 1 contains a list of selected bond distances and
. The Cu(1)-N(pyr) (N1, N3 or N5)
, 2.11 Å in and 2.073 Å in 4.
1-4
1
2
3
Ms
7
adducts Tp Cu(olefin) (2.15-2.21 Å) or in the alkyne adducts
Ms
8
Tp Cu(alkyne) (2.10 Å). This is probably the result of the
exclusive sigma donation of the amine ligand to the metal
centre in contrast with the back-bonding capabilities of both
olefin and alkyne ligands. The Cu-N(amine) distance also
deserves some comment. The Cu(1)-N(7) distance in
7
of
1
.960(2)
Å
is similar to those previously found in
1
2a
CuCl(NH
3
)(olefin) (1.987Å)
2b
3
or Cu(L)(NH ) (1.973 Å, L =
1
bidentate ligand).
Such distance slightly increases when
Ms
3
1. ORTEP view of the molecule of complex Tp Cu(NH ) (1)
Figure
(
Hydrogen atoms of the pyrazolyl groups have been omitted for clarity)
adduct.
Figure 1 shows the structure of the molecules of
result of X-ray diffraction studies. The complex is
1
as the
Ms
3
mononuclear, with the Tp ligand coordinated in a κ -N,N,N
fashion and the NH moiety bonded to the copper centre
3
occupying the fourth coordination site of a slightly distorted
tetrahedron formed by the four N donors. Additional
comments on distances and angles are provided in the next
section.
Ms
2 2
Figure 2. ORTEP view of the molecule of complex Tp Cu(NH CH Ph) (4)
(
Hydrogen atoms of the pyrazolyl groups have been omitted for clarity)
moving from
1 to 4, probably accounting for the augment of
Table 1. List of selected bond distances [Å] and angles [°] for copper compounds 1-4.
1
2
3
4
Cu-N(7)
Cu-N(1)
Cu-N(3)
Cu-N(5)
1.960(2)
1.985(9)
2.082(2)
2.082(2)
2.082(2)
2.006(5)
2.1309(17)
2.090(4)
2.1309(17)
2.011(4)
2.0841(14)
2.0882(16)
2.0538(15)
2.0959(13)
2.0884(13)
2.0505(14)
Ms
Scheme 2. Synthesis of the Tp Cu(amine) adducts 2-4
.
Ms
N(1)-Cu-N(7)
N(3)-Cu-N(7)
N(5)-Cu-N(7)
126.90(12)
115.93(9)
132.22(11)
140.0(4)
115.0(4)
118.9(7)
108.84(15)
129.87(16)
132.96(15)
135.00(12)
121.19(13)
118.85(13)
Synthesis and characterization of complexes Tp Cu(NR ) (2-5).
3
For the sake of comparison with the ammonia adduct
1 we
have prepared a series of amine adduct of general composition
Ms
Tp Cu(NR3) (Scheme 2) upon ligand exchange from
Ms
Tp Cu(THF) at room temperature. Crystalline materials were
collected in 60-80% yield upon direct cooling of the reaction the steric volume of the amine ligand.
2
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The relative reactivity of the above complexes toward amine good agreement with this, two sets of resonances for the
exchange has been studied (Scheme 3). Thus, when complex mesytil pyrazolyl units are observed in the NMR with relative
was reacted with one equiv of either diethyl or benzylamine, ratio 2:1. In addition, a weak NOE effect has been detected
complete conversion into or was respectively observed between the NH hydrogen nuclei and the aromatic
whereas bubbling of ammonia through the solutions of
returned in solution. From these results it seems reasonable
1
3
4
2
3-4
resonances. These data support the proposal of a certain
1
proposing that the substituted amine provides more stable
adducts albeit the difference in energy is not large given the
possibility of reversion with excess of ammonia.
Scheme 3. Amine exchange in complexes 1-4
Scheme 4. Top: the targeted transformation. Bottom: the observed
transformations. Leading to complexes 5 and 6.
Ammonia N-H functionalization.
N-H cleavage and N-C bond formation. On the basis of the
availability of the ammonia complex , we have studied its
2
interaction of the NH hydrogens with the π-system of the
mesytil rings. This would preclude the rotation of the Cu-
1
reactivity toward hydrogen abstraction, with the aim of the
consecutive formal proton and hydride abstraction and final
N(amine) bond, decreasing the symmetry of the molecule. To
2
,3
nitrene formation (Scheme 4). We planned the use of lithium
diisopropylamide (LDA) and a triphenylmethyl salt (Ph CPF ) as
3
6
respective proton and hydride scavengers. The one-pot
reaction, either at low or room temperature, led to a
somewhat dirty reaction mixture from which we have isolated
Ms
Ms
two products: Tp Cu(NH
Separate experiments carried out with
respectively, have afforded compounds
Scheme 4).
The formation of complex
2
CPh
3
) (
5
) and Tp Li(THF) (
6).
1
and LDA and Ph CPF ,
6
3
6
and
CPF
5
, respectively
(
5
from
1
and Ph
3
6
escapes from
the common role of hydride scavenger. Formally, the Ph
group replaces one of the H atoms of ammonia, HPF being
likely formed for reaction balance. Complex was isolated in
6 % yield from that reaction mixture as colourless crystals,
3
C
6
5
1
some of them suitable for an X-ray diffraction studies. Figure 3
shows the ORTEP view where the formation of
triphenylmethylamine is demonstrated. Moreover, this
Ms
2 3
Figure 3. Structure of Tp Cu(NH (CPh )) 5 (Hydrogen atoms of the
compound has been independently prepared upon reacting
Ms
pyrazolyl groups have been omitted for clarity)
Tp Cu(THF) and commercial NH
2
CPh
3
following the
(see
aforementioned procedure described for compounds 2-4
ESI). Spectroscopic, analytical and even structural data for both
samples were identical.
Ms
shed light on this idea, the related complex Tp Cu(NH CHPh )
2
2
(
7
) bearing diphenylmethylamine has been prepared and fully
characterized, including X-ray studies (see ESI for full details).
The absence of the third phenyl group in decreases the steric
The solid-state structure of
interesting features. A similar, distorted tetrahedral geometry
is observed around the copper centre for . However, in the
case of the values of the Cu-N(pyr) distances are somewhat
5 (Figure 3) has shown some
7
1-5
pressure around the metal centre to such extend that the Cu-
N(pyr) distances found are very similar to those already
5
larger: 2.340 Å for Cu(1)-N(1) and 2.301 Å Cu(1)-N(2), the third
commented for complexes 1-4 (Scheme 5).
one yet resembling the values found for 1-4 (See Scheme 5). In
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Complex Tp Li(THF) (
Journal Name
Ms
Ms
) has been isolated as colourless transformations. This is at variance with our Tp Cu-based
6
crystals, from which NMR data showed the typical pattern of system, for which the copper-carbene intermediates have
Ms
14
the coordinated Tp
ligand as well as coordinated already been detected and spectroscopically characterized.
Ms
tetrahydrofuran. The observation of a slight difference in the From this Tp Cu=C(H)CO
2
Et species, it is very likely that a N-
chemical shifts and the lack of good elemental analysis ylide is formed, since a related transformation with esters and
1
5
prompted us to determine its X-ray structure from which the similar catalysts have revealed such behaviour. A final 1,2-
presence of lithium, and not copper, bonded to the ligands shift from the ylide to the formal insertion product would
was assessed. The loss of copper could be related with the account for the formation of the aminoacid derivative.
highly reductant power of LDA, albeit we have not been able
to isolate any copper species from the reaction mixture. We
believe that this finding is of interest for the researchers in the
field of tryspyrazolylborate-containing transition metal
complexes, since this simple “transmetallation” is not
expected
H
N2
NH3(g)
NH2
CO2Et
HN
H
H
+
H
CO2Et
TpMsCu(THF)
CO2Et
H
H
H
CO Et
2
1
:
1
yield > 95%
N
N
Cu
TpMsCu
B
N2
N
H
CO2Et
N2
N
N
N
N
N
N
-
THF
B
Cu
O
CO2Et
H
B
Cu
B
Cu
+
THF
N
N
N
NH3(g)
NH2
CO Et
2
H3N
H
CO2Et
H
H
Scheme 5. Comparison of bond distances (Å) around the copper centre for
Ms
several complexes Tp Cu(amine),
Scheme 6 Top: Formation of glycine derivatives from ammonia. Bottom:
plausible reaction pathway.
Ammonia N-H functionalization by carbene insertion.
Last decade we reported on the catalytic insertion of
carbene CHCO
2
Et units (from ethyl diazoacetate) into N-H
x
bonds of several amines in good yields with several Tp CuL Conclusions
1
0
complexes as the catalyst. In spite of the interest of this
reactions, that lead to aminoacid formation, its application to
ammonia as the substrate is reduced to the work by Gross and
We have prepared and fully characterized the ammonia
Ms
x
3
complex Tp Cu(NH ) (1), that completes a series of Tp CuL
complexes (L = MeCN, CO, olefin, alkyne), a a series of related
Ms
Tp Cu(amine) complexes. The N-H bond of coordinated
9
co-worker with an iron-based catalyst. On the basis of this, we
have now studied the catalytic potential of the complex
Ms
Tp Cu(THF) toward the reaction of ethyl diazoacetate and
ammonia has been replaced with the bulkier Ph
3
C group upon
CPh ) in a rare
example in which the trytil cation does not formally acts as
hydride scavenger. The reaction of with a strong base such as
LDA induced the decomposition of
Ms
reaction with Ph
3
CPF
6
, yielding Tp Cu(NH
2
3
ammonia. The reaction was performed upon dissolving the
catalyst in dichloromethane followed by saturation of the
solution with ammonia gas. After 10 min of bubbling, EDA was
slowly added with the aid of a syringe pump for 1h. After that
time, the reaction mixture was stirred for additional 72h and
the reaction was investigated by GCMS. A mixture of the two
products derived from the formal insertion of one or two
carbene groups into the N-H bonds of ammonia in relative
ratio of 50:50 (Scheme 6) was observed, with an overall yield
of >95% (EDA-based). These results brings copper into line
with iron for the direct transformation of ammonia into glycine
ester.
1
Ms
1
toward Tp Li(THF), an
unexpected case of transmetallation reaction. In addition to
the above stoichiometric N-H functionalization, the first
copper-catalyzed activation of ammonia N-H bonds has been
Ms
achieved with Tp Cu(THF) as the catalyst for the reaction with
ethyl diazoacetate, leading to glycine derivatives.
Experimental
1
3
Gross and co-worker reported on the mechanism of the iron-
based reaction to occur with no formation of iron-carbene
intermediates, at variance of many other metal-diazoacetate
General Methods. All procedures were performed in a
glovebox under an inert atmosphere of dinitrogen or using
standard Schlenk techniques. All substrates were purchased
4
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from Sigma-Aldrich and used without further purification. (d, 2H, J = 6.9 Hz, CHarom amine), 6.79 (s, 6H, CHmesityl), 7.23 (m,
1
3
1
3
H,CHarom amine), 7.79 (d, 3H, J = 2 Hz, CHpyrazol). C{ H} NMR (125
MHz, CD Cl ): δ 20.2 (CH3mesityl), 20.6 (CH3mesityl), 48.8 (CH2amine),
03.6 (CHpyrazol), 126.2 (CHarom amine), 126.9 (Cqarom amine), 127.5
(CHmesityl), 128.3 (CHarom amine), 132.3(Cqmesityl), 133.9 (CHpyrazol), 136.9
Solvents were dried and degassed before use. The
4a
Ms
Tp Cu(THF) complex was prepared according to literature
methods. NMR spectra were recorded on Agilent 400 MR or
2
2
1
1
13
Agilent 500 DD2, H and C NMR shifts are reported relative to
tetramethylsilane. FT-IR spectra were collected on a Nicolet
IR200 FTIR spectrometer. Elemental analyses were performed
on a Perkin-Elmer Series II CHNS/O Analyzer 2400.
(
C
qmesityl), 137.6 (Cqmesityl
)
,
141.4 (Cq arom amine), 149.3 (Cqpyrazol).
Ms
Tp Cu(Triphenylmethylamine) (5). Anal. Calcd for C55
7
H57CuN : C
7
4.19; H, 6.45; N, 11.01. Found: C, 74.36; H, 6.45; N, 11.05. IR(KBr):
-1
-1
1
ν(B-H), 2255 cm ; ν(N-H), 3305, 3255 cm . H NMR (500 MHz,
CD Cl ): δ 1.80 (s, 6H, CH3mesityl), 1.81 (s, 12H, CH3mesityl), 1.93 (s, 6H,
CH3mesityl), 2.30 (s, 3H, CH3mesityl), 3.26 (s, 2H, NH ), 5.98 (d, 2H, J = 2
Ms
Ms
Synthesis of Tp Cu(NH
0
3
) (1). The complex Tp Cu(THF) (0.22g,
was
2
2
.31 mmol) was dissolved in dichloromethane (20 mL) and NH
3
2
bubbled through the solution at room temperature for 10 min. The
solution was cooled at -30ºC leading to the isolation of colourless
crystalline material in 95% yield after successive crops. Anal. Calcd
Hz, CHpyrazol), 6.02 (d, 4H, J = 7.6 Hz, CHarom amine), 6.08 (d, 1H, J = 2
Hz, CHpyrazol), 6.32 (s, 4H, CHmesityl), 6.75 (s, 2H, CHmesityl), 7.07 (t, 4H,
J = 7.6 Hz, CHarom amine), 7.26 (m, 7 H, CHarom amine), 7.78 (d, 2H, J = 2
for C36
H43BCuN
7
•CH
2
Cl
2
: C, 60,62; H, 6.19; N, 13.37. Found: C,
13
1
Hz, CHpyrazol), 7.82 (d, 1H, J = 2 Hz, CHpyrazol). C{ H} NMR (125 MHz,
CD Cl ): δ 20.0 (CH3mesityl), 20.4 (CH3mesityl), 20.6 (CH3mesityl), 20.9
CH3mesityl), 103.9 (CHpyrazol), 106.1 (CHpyrazol), 126.5 (C
-
1
-
6
0.24; H, 6.21; N, 13.17. IR(KBr): ν(B-H), 2434 cm ; ν(N-H), 3375 cm
br). H NMR (500 MHz, CD
CH3mesityl), 2.25 (s, 9H, CH3mesityl), 6.03 (d, 3H, J = 2 Hz, CH pyrazol), 6.81
s, 6H, CHmesityl) 7.77 (d, 3H, J = 2 Hz, CHpyrazol). C{ H} NMR (125
MHz, CD Cl ): δ 20.1 (CH3mesityl), 20.7 CH3mesityl), 103.8 (CHpyrazol),
27.5(CHmesityl), 132.1 (Cqmesityl), 133.8 (CHpyrazol), 136.8 (Cqmesityl
37.5 (Cqmesityl), 149.3 (Cqpyrazol).
2
2
1
1
(
2
Cl
2
): δ 0.59 (s, 3H, NH
3
), 1.92 (s, 18H,
(
(
(
q
), 126.8
CHarom amine), 127.4 (CHarom amine), 127.8 (CHarom amine), 127.8
CHmesityl), 128.0 (CHmesityl), 128.0 (CHarom amine), 128.3 (CHarom amine),
1
3
1
(
2
2
1
1
30.2 (Cq), 131.7 (Cq), 134.9 (CHpyrazol), 135.9 (CHpyrazol), 136.8 (Cq),
37.2 (Cq),137.3 (Cq), 145.8 (Cq), 148.84 (Cq), 150.4 (Cq), 152.5
1
1
)
,
(
Cq).
Ms
General synthetic protocol for complexes Tp Cu[amines] (2-5 and
7
Ms
7
Tp Cu(Diphenylmethylamine) (7). Anal. Calcd for C49H53BCuN : C,
Ms
). To a solution of complex Tp Cu(THF) (0.08 g, 0.114 mmol)
in dichloromethane (15 mL) 4 equiv of the corresponding
amine were added (0.34 mmol). After 5 min of stirring the
solvent was concentrated and the solution cooled at -30ºC
2-5 were collected in 60-80%
yield. The complex was prepared in the same way but adding
only one equivalent of amine. The crystalisation was
performedand in pentane (5-10 mL) to obtain yellow crystals.
7
2.27; H, 6.57; N, 12.04. Found: C,71.92; H, 6.842; N, 11.99. IR(KBr):
-1
-1
1
ν(B-H), 2434 cm ; ν(N-H), 3262, 3311 cm (br). H NMR (500 MHz,
CD Cl ): δ 1.91 (s, 18H, CH3mesityl), 2.09 (s, 9H, CH3mesityl), 3.76 (br, 1H,
CHamine), 6.04 (d, 3H, J = 2 Hz, CHpyrazol), 6.50 (br, 4H, CHarom amine),
.56 (s, 6H, CHmesityl), 7.20 (m, 6H,CHarom amine), 7.80 (d, 3H, J = 2 Hz,
2
2
from which colourless crystals of
7
6
13
1
CHpyrazol). C{ H} NMR (125 MHz, CD
CH3mesityl), 61.4 (CHamine), 104.0 (CHpyrazol), 126.2 (CHarom amine), 126.8
2
2
Cl ): δ 20.3 (CH3mesityl), 20.8
(
(
Cqarom amine), 127.9 (CHmesityl), 128.1 (CHarom amine), 131.9(Cqmesityl),
43 % Yield.
1
1
34.3 (CHpyrazol), 136.9 (Cqmesityl), 137.1 (Cqmesityl
49.9 (Cqpyrazol).
,
) 143.9 (Cqarom amine),
Ms
7 2 2
Tp Cu(ethylamine) (2). Anal. Calcd for C38H47BCuN •½CH Cl : C,
6
4.34; H, 6.73; N, 13.64. Found: C, 64.50; H, 6.75; N, 13.33. IR(KBr):
-1
-1
1
ν(B-H), 2422 cm ; ν(N-H), 3313, 3267 cm (br) H NMR (500 MHz,
CD Cl ): δ 0.12 (br s, 3H, CH3amine), 0.85 (br s, 2 H, NH ), 1.37 (br s,
Ms
2
2
2
Isolation of Tp Li(THF) (6). This complex was isolated from the
reaction of complex 1 (0.1 mmol) and LDA (0.1 mL of a 2 M solution
in THF) or BuLi (0.08 mL of a 2,5 M solution in Hexane). The first
method complex 1 was dissolved in dicloromethane (10 mL) and
cooled to -50 ° C .Next was added LDA. The reaction was stirred for
2
3
H, CH2amine) , 1.89 (s, 18H, CH3mesityl), 2.21 (s, 9H, CH3mesityl), 6.00 (d,
H, J = 2 Hz, CHpyrazol), 6.78 (s, 6H, CHmesityl) 7.74 (d, 3H, J = 2 Hz,
1
3
1
CHpyrazol). C{ H} NMR (125 MHz, CD
2
Cl
2
): δ 16.8 (CH3amine), 20.2
(
(
(
CH3mesityl), 20.6 (CH3mesityl), δ 39.5 (CH2amine), 101.6 (CHpyrazol), 127.4
CHpyrazol), 132.2 (Cqmesityl), 133.8 (CHpyrazol), 136.8 (Cqmesityl), 137.5
Cqmesityl), 149.4 (Cqpyrazol).
3
0 min. After was filtered and concentrated and cooled at -30ºC.
White-Brown crystals were obtained that correspond to compound
6) Yields 32%. the second method to solution of 1 in (15 mL) of
(
Ms
7
Tp Cu(diethylamine) (3). Anal. Calcd for C40H51CuN : C, 68.22; H
tetrahydrofurane was added 100 µL of BuLi .The reaction followed
the same previous procedure to give white crystals. Yield 36%
7.30; N, 13.92. Found: C, 68.03; H, 7.63; N, 13.76. IR(KBr): ν(B-H),
-1
-1 1
6 6
2445 cm ; ν(N-H), 3249, 3264 cm . H NMR (500 MHz, C D ): δ 0.24
(
2
3
t, 6H, CH3amine), 1.28 (s, 1H, NHamine), 1.58 (m, 2H, CH2amine), 1.78 (m,
Anal. Calcd for C40
H
48BLiN
6
O : C 74.3 , H 7.48, N 13.00. Found: C
Cl ): δ 1.22 (s, 4H,
H, CH2amine), 2.06 (s, 9H, CH3mesityl), 2.08 (s, 18H, CH3mesityl), 5.97 (d,
H, J = 2 Hz, CHpyrazol), 6.71 (s, 6H, CHmesityl) 7.77 (d, 3H, J = 2 Hz,
7
4.55, H 7.55, N 13.27. 1H NMR (400 MHz, CD
2
2
CH2thf), 1.85 (s, 18H, CH3mesityl), 2.20 (s, 9H, CH3mesityl), 2.69 (s, 4H,
CH2thf), 5.97 (d, 3H, J = 2 Hz, CHpyrazol), 6.77 (s, 6H, CHmesityl) 7.78 (d,
1
3
1
CHpyrazol). C{ H} NMR (125 MHz, C
6
D
6
): δ 12.6 (CH3amine), 20.6
(
(
(
CH3mesityl), 20.7 (CH3mesityl), 42.9 (CH2amine), 104.0 (CHpyrazol), 127.6
3
2 2
H, J = 2 Hz, CHpyrazol). 13C{1H} NMR (125 MHz, CD Cl ): δ 20.1
CHmesityl), 133.0 (Cqmesityl), 134.9(CHpyrazol), 136.6 (Cqmesityl), 137.8
Cqmesityl), 150.1 (Cqpyrazol).
(
(
(
CH3mesityl), 20.6 (CH3mesityl), 24.9 (CH2thf), 66.9 (CH2thf), 103.9
CHpyrazol), 127.3(CHmesityl), 132.2 (Cqmesityl), 134.8 (CHpyrazol), 136.7
Cqmesityl), 137.5 (Cqmesityl), 150.7 (Cqpyrazol).
Ms
7 2 2
Tp Cu(benzylamine) (4). Anal. Calcd for C43H49BCuN •⅓CH Cl : C,
6
7.92; H, 6.53; N, 12.80. Found: C, 68.36; H, 6.47; N, 12.94. IR(KBr):
X-ray structure determination. The structures of complexes
have been determined and deposited in the CCDC with the
following codes: , CCDC-1443209; , CCDC-1443210; , CCDC-
1-7
-1
-1 1
ν(B-H), 2421 cm , ν(N-H), 3321, 3271 cm . H NMR (500 MHz,
CD Cl ): δ 1.24 (t, 2H, NH2amine), 1.96 (s, 18H, CH3mesityl), 2.15 (s, 9H,
CH3mesityl), 2.39 (t, 2H, CH2amine), 6.06 (d, 3H, J = 2 Hz, CHpyrazol), 6.50
2
2
1
2
3
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
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Dalton Transactions
Page 6 of 6
View Article Online
DOI: 10.1039/C5DT04972E
ARTICLE
Journal Name
1443211;
4, CCDC-1443212; 5, CCDC-1443213; 6, CCDC-
1
443214 and
7
, CCDC-1443215. See ESI for full details on their 10 See for example: M. E. Morilla, M. M. Díaz-Requejo, T. R.
Belderrain, M. C. Nicasio, S. Trofimenko and P. J. Pérez,
Chem. Commun., 2002, 2998 and references cited therein.
determination.
1
1
1 K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds; 5ª ed, John Wiley & Sons:
Hoboken, New Jersey, 2009.
2 (a) G. Groger, F. Olbrich, P. Schulte and U. Behrens, J.
Organomet. Chem., 1998, 557, 251. (b) J. B. Tommasino, F.
Ms
Amine Exchange Reactions. A solution of Tp Cu(NH
.6mL of deuterated solvent dichloromethane was placed in a
NMR tube and one equiv of the corresponding amine was
added. NMR analysis showed the formation of or in a few
minutes. Complex was restored upon bubbling ammonia gas
3
) (1) in
0
3
4
N. R. Renaud, D. Luneau and G. Pilet, Polyhedron, 2011, 30
663.
13 I. Aviv and Z. Gross, Chem. Eur. J., 2008, 14, 3995-4005.
,
1
1
through the solution for several minutes.
1
4 A. Pereira, Y. Champouret, C. Martín, E. Álvarez, M. Etienne,
T. R. Belderraín, and P. J. Pérez, Chem. Eur. J. 2015, 21, 9769.
5 R. Gava, M. A. Fuentes, M. Besora, T. R. Belderrain, K. Jacob,
F. Maseras, M. Etienne, A. Caballero and P. J. Pérez,
Carbene transfer reaction from ethyl diazoacetate (EDA) to
Ms
1
ammonia.
A solution of Tp Cu(THF) (0.08 mmol) in
dichloromethane 20 mL was saturated with ammonia upon
gentle bubbling for 15 min. Then the NH3 supply was
disconnected and a solution of EDA (1.6 mmol in 5 mL of
dichloromethane) was slowly added for 1 h. After an overall 72
h time of stirring, the mixture was taken to dryness and the
residue was investigated by NMR spectroscopy that show the
exclusive formation of ethyl glycinate ester NH CH CO Et and
ChemCatChem 2014, 6, 2206.
2
2
2
the bis-functionalized product NH(CH CO Et) in ca. equimolar
2
2
2
amounts (yields established by GCMS). No carbene dimers nor
unreacted EDA was observed after that time.
Acknowledgements
We thank Prof. Kurt Mereiter for helpful discussions. Support
for this work was provided by the MINECO (CTQ2014-52769-
C3-1-R), and the Junta de Andalucía (P10-FQM-06292).
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6
| J. Name., 2012, 00, 1-3
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