Ligand-dependent formation of ion-pair CuI/CuIII trifluoromethyl complexes containing bisphosphines

Article abstract of DOI:10.1039/c6dt03016e

We report novel ion-pair bisphosphine Cu^I/Cu^III trifluoromethyl complexes [(P₂)₂Cu^I]⁺[Cu^III(CF₃)₄]^- (P₂ = DPPE, BINAP or Xantphos) fea

Full text of DOI:10.1039/c6dt03016e

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Ι
ΙΙΙ
Ligand-Dependent Formation of Ion-Pair Cu /Cu Trifluoromethyl
Complexes Containing Bisphosphines†
View Article Online
DOI: 10.1039/C6DT03016E
Song-Lin Zhang* and Wen-Feng Bie
Received (in XXX, XXX) Xth XXXXXXXXX 200X, Accepted Xth XXXXXXXXX 200X
First published on the web Xth XXXXXXXXX 200X
DOI: 10.1039/b000000x
5
Ι
ΙΙΙ
ΙΙΙ
We report novel ion-pair bisphosphine Cu /Cu trifluoromethyl
(bpy)Cu (CF
box). Complexes 1 and 2 were found to be highly efficient for
Xantphos) that are prepared via oxidative trifluoromethylation 55 the trifluoromethylation of arylboronic acids under mild
3 3
) (2) in much higher yields (Scheme 2, red
+
−
complexes [(P ) Cu] [Cu(CF ) ] (P2 = DPPE, BINAP or
2
2
3 4
conditions, but the ion-pair 1′ was unreactive under similar
1
1
2
0
5
0
of CuI with CF SiMe in the presence of AgF. The bisphosphine
3
3
I
III
conditions. These findings provide fundamental information
Cu /Cu
CF
3
complexes are highly reactive for aerobic
ΙΙΙ
about the structures and reactivity of phen-containing Cu -
trifluoromethylation of arylboronic acids to produce
trifluoromethylated arenes in good to quantitative yields, which
3
CF complexes that are closely relevant to a rich branch of
60 trifluoromethylation reactions promoted by Cu/phen system.
I
III
is in sharp contrast to the Cu /Cu complex with phen/PPh3
ligands (1′). These results not only provide strong evidence that
(a) Burton's seminal work
S
III
3
both the neutral and ion-pair Cu CF complexes are competent
N
S
catalytic species for Cu-mediated oxidative trifluoromethylation
reactions, but also have important mechanistic implications that
the active catalyst and reaction mechanism should be distinct
and ligand-dependent for trifluoromethylation reactions with
different types of ancillary ligands.
S
N
S
S
CF
3
S
+
CuΙ]ꢀ
CuΙΙΙ
ArX
[
CdΙ] [(CF
3
)
2
N
Ar-CF
3
o
o
CF3 90-100 C
DMF, -30 C to RT
The first example
(
b)
CF
3 3
SiMe , AgF
F
3
C
CF
CuΙΙΙ
3
N
N
CuΙΙΙ
Copper-mediated trifluoromethylation reactions of aryl halides,
N
P
N
N
N
CuΙ
CH Cl , RT
CuΙ
+
F
3
C
CF3
2
2
boronic acids and other reagents with various CF
3
sources
• precursors) have
In contrast to the flourishing
F3C
Ph
3
P
CF3
Ph
3
Br
CF
3
−
+
PPh
3
(
formally divided into CF
3
1
, CF
3
and CF
3
1'
1
-6
2
3
3
4
4
5
5
0
5
0
5
0
been intensively studied.
ArB(OH)2
ArB(OH)
2
achievements in the development of reaction methodologies,
the mechanisitc aspects have been far less elucidated. The
identity and reactivity properties of the active copper CF3
species remains elusive for many trifluoromethylation
reactions, which are however essential to the understanding
Ar-CF
highly reactive
up to quantitative yields
3
unreactive
ΙΙΙ
3
Scheme 1 Synthesis and reactivity of isolated Cu CF complexes.
L (1 equiv.)
7
,8
3 3
CF SiMe (6 equiv.)
and design of trifluoromethylation chemistry. Particularly,
AgF (4 equiv.)
LCuΙΙΙ(CF3)3
or
[L Cu ] [CuΙΙΙ(CF ) ]
Ι
+
—
CuI
2
3
4
the isolation, characterization and reactivity properties of
DMF, RT, 18 hours
ΙΙΙ
Ligand-dependent chemoselectivity
high-valent Cu -CF
3
complexes, catalytically relevant
intermediates proposed in oxidative or electrophilic
trifluoromethylation reactions, present a challenge awaiting to
+
Ph
P
2
Ph2
CF
3
N
N
P
Ι
—
ꢁ
CuΙΙΙ CF3
Cu
CuΙΙΙ(CF3)4
9
,10
be addressed.
Among the sporadic examples of well-
P
P
ΙΙΙ
10
Ph
Ph
CF
3
2
2
characterized Cu -CF complexes, Burton et al. described a
poineering study on the preparation of a dithiocarbamato Cu
3
ΙΙΙ
3
+
1
2
Ι
Ph
2
2
Ph
P
2
bis-CF
3
complex by oxidation of Cu -CF
3
precursors with
P
CF
3
Ι
ꢁ
—
Cu
CuΙΙΙ(CF
3 4
)
thiuramdisulphide and its reactivity toward aryl iodides to
N
CuΙΙΙ CF
CF3
P
P
o
3
Ph
Ph
2
produce trifluoromethylated arenes at 90-100 C (Scheme
N
1
0a
1
a).
isolation, characeterization and reactivity properties of Cu -
CF complexes proposed in trifluoromethylation chemistry.
More recently, we reported a room-temperature preparation
This seminal work represents the first example of
4
ΙΙΙ
+
PPh
2
2
Ph P
3
CuΙ
CuΙΙΙ(CF3)
ꢁ
4
—
O
O
N,N-ligands
ΙΙΙ
and characterization of both neutral Cu -CF
and ion-pair 1′ containing representative phen ligand (Scheme
b). Our method involves formally oxidative transmelation of
phenCuBr with CF SiMe in the presence of AgF in CH Cl
3
complexes 1
Neutral CuΙΙΙ-CF
PPh
2
Ph P
2
3
complexes
ref.11
5
Ι
ΙΙΙ
1
P,P-ligands
Ion-pair Cu /Cu complexes
3
3
2
2
This study
1
1
(Scheme 1b). By using a sligthly different method starting
Scheme 2 A general and ligand-dependent method for selective synthesis
ΙΙΙ
Ι
ΙΙΙ
from CuI and change of the solvent to more polar DMF, we 65 of either neutral Cu or ion-pair Cu /Cu trifluoromethyl complexes 1-5.
ΙΙΙ
could access selectively neutral phenCu (CF ) (1) and
3
3
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Journal Name, [year], [vol], 00–00 | 1

Dalton Transactions
Page 2 of 6
ΙΙΙ
+
In an attempt to broaden this Cu -CF
3
chemistry and to
anion and
a
tetrahedral [Cu(DPPE)
2
]
counterion are
View Article Online
establish potential ligand-reactivity relationship, other 50 unambugously observed in the crystal structure. The average
DOI: 10.1039/C6DT03016E
ancillary ligands need to be investigated. Considering the
popular use of bisphosphine ligands in trifluoromethylation
and also other transition metal catalysis, it should be of
3
Cu-CF bond lengths are ca 1.952(5) Å, which are disturbed
by the disorders of the carbon atoms of CF ligands.
3
1
2
5
0
5
0
oxidation
broad interest to isolate possible bisphosphine-containing
CuI/L
2CF SiMe3
Ag0 + AgI
CF
3
ΙΙΙ
CuΙΙ
Cu -CF complexes and to study their structural and
L
+
3
+
3
1
CF
3
+ 2 FSiMe
3
reactivity properties. Thus we studied typical bisphosphine
+ 2AgF
transmetalation
A
ligands DPPE, BINAP and Xantphos under the reaction
conditions in Scheme 2. To our surprise, ion-pair Cu /Cu
trifluoromethyl complexes 3-5 (Scheme 2, blue box) were
Ag mirror observed
FSiMe3 detected by 19F NMR
Ι
ΙΙΙ
1
1
2
L = phen, bpy,
DPPE, Xantphos, BINAP
Disproportionation
Equilibrium
Ι +
selectively obtained in high yields without significant
ΙΙΙ
amounts of neutral Cu -CF complexes detected.
CF3
3
ΙΙΙ
Complexes 3-5 were prepared by reaction of CuI with 1
equivalent of bisphosphine (DPPE, BINAP and Xantphos), 6
L
Cu
CF
3
+
L
CuΙ CF3
Cu ] [CuΙΙΙ(CF ]−
)
3 4
[L
2
CF
3
B
C
D
equivalents of CF
AgF in DMF at room temperature under N
Scheme 2). After workup, recrystallization and column
3
SiMe
3
as the CF
3
source in the presence of
atmosphere
Scheme 3 Plausible mechanism for the formation of 1-5.
2
(
1
1
ΙΙ
I
III
55
3
As proposed in our previous study, Cu -CF intermediates
chromatography, ion-pair Cu /Cu CF3 complexes 3-5 with
DPPE, BINAP and Xantphos were isolated and purified in
good to excellent yields of 65%, 93% and 90% (see ESI for
more details of synthesis and purification).†
A should probably be generated initially via oxidation and
transmetalation (Scheme 3). The observation of Ag mirror and
some green impurity during workup, and the detection of
1
9
FSiMe at ca -157 ppm in F NMR supports this proposal. A
3
ΙΙΙ
Ι
6
6
7
7
8
8
9
0
5
0
5
0
5
0
could disproportionate into LCu (CF ) (B) and LCu CF (C)
3
Ι +
3
3
ΙΙΙ
−
that is in equilibrium with [L
2
Cu ] [Cu (CF
3
)
4
]
(D) after
L/CF ligand exchange between B and C (Scheme 3). Due to
3
the much stronger coordinating ability of bisphosphines than
phen or bpy and the polar solvent, this equilibrium should be
irreversibly driven to the side of ion-pair complexes D for
bisphosphines. In constrast, for less electron-rich N,N-
chelates phen and bpy, the left side B + C should instead be
dominant. Moreover, the presence of excess AgF and
CF SiMe may further enable iterative oxidation of C to A
3
3
and disproportionation of
A to B+C, resulting in the
Fig. 1 ORTEP drawing of complex 3 with thermal ellipsoids at 50%
probability. All the hydrogen atoms, one solvent molecule and disorders
of carbon and fluorine atoms of CF s are removed for clarity.
3
accumulation of B. This well rationalizes the selective
formation of neutral type B for phen and bpy while ion-pair D
type complexes for bisphosphines. The proposal of the
equilibrium between B+C and D, and the effect of ancillary
ligand-coordinaing ability on the equilibrium are supported by
the observation that addition of excess phen to the solution of
ion-pair 4 allow the access of neutral 1 in an isolated yield of
2
5
1
9
F NMR spectra of 3-5 show only one singlet resonance
around -34.7 ppm, which corresponds to four equivalent CF
3
ΙΙΙ
−
1
groups in [Cu (CF ) ] . H NMR spectra of 3-5 show
3
4
3
3
4
4
0
5
0
5
characteristic resonances and splittings of protons of
coordinating DPPE, BINAP and Xantphos that are
significantly low-field shifted in the aromatic region
compared to the free ligands (see ESI for more details).† Most
6
0% (please see ESI for more details)†. Possibly, ligand
exchange between 4 and phen results in the formation of
Ι
+
ΙΙΙ
−
transient [(phen)(BINAP)Cu ] [Cu (CF ) ] (which parallels
3
4
3
1
remarkable are the P NMR behaviour of 3-5. 3 shows only
one resonance of broad singlet at +4.7 ppm, consistent with
the tetrahedral geometry where all the four P atoms are totally
closely to complex 1′) that is unstable and equilibriates
ΙΙΙ
preferentially to the neutral phenCu (CF
3
)
3
(1) in the
presence of excess phen. Similar conversion of 1′ to 1 in the
presence of excess phen has already been observed in our
3
1
equivalent. In constrast, P NMR spetrum of 4 shows two
major doublet singnals at +15.9 and +14.4 ppm with coupling
constants of 17.4 Hz in a ratio of 1:1. This may be caused by
the P-P coupling of R- and S-enantiomer of the racemic
11
previous study.
Next, reactivity properties of complexes 3-5 were studied
by reaction with arylboronic acids. For ion-pair complex 3,
14
3
1
BINAP used in our study. In P NMR of 5, there are also two
DMF is ineffective for trifluoromethylation of arylboronic
acid 6a (Table 1, entries 1,2). In nonpolar toluene, it was
exciting to see that reaction of complex 3 with 6a gave the
resonances at -8.2 and -9.7 ppm with doublet splittings
(
coupling constants of 18.0 Hz). This can be rationalized that
the presence of endo/exo face of one Xantphos distinguishes
o
trifluoromethylated product 7a in 76% yield at 80 C for 18
the two P atoms of another Xantphos in the tetrahedral
hours, without the assistance of any additive (entry 3). The
great promotion effect of non-polar toluene implies that
neutral type B and/or C may also be involved in the aerobic
+
geometry of [(Xantphos)
2
Cu] moiety.
The structure of 3 was further confirmed by X-ray
1
3
−
diffraction analysis (Fig 1). A square planar [Cu(CF ) ]
3
4
95 trifluoromethylation since less polar solvent is expected to
2
|
Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 3 of 6
Dalton Transactions
favor their generation from the equilibrium in Scheme 3.
Trifluoromethylated arenes 7 were thus prepraed in generally
View Article Online
good to quantitative yields regardless of the electronic
DOI: 10.1039/C6DT03016E
ab
Table 1 Reactivity studies of 3 with arylboronic acid 6a
2
3
3
5
0
5
properties of the substituents. However, the reaction exhibits a
significant steric effect for ortho-substituted arylboronic acid.
For example, 7m with an ortho-OMe was obtained in only
73%, which is much lower than the quantitative yied of
regiomer 7a with a para-OMe.
Similarly, complexes 4 and 5 also show up to quantitative
reactivity toward aerobic trifluoromethylation of arylboronic
acids under mild conditions. Some selected examples are
summarized in Table 3 and 4 (see ESI for more details).†
These results on the reactivity properties strongly imply that
3-5 are competent as reactive intermediates in oxidative
+
B(OH)
2
CF3
Ph
P
2
2
Ph2
P
Additive, Solvent
Temp, Time
Ι
—
+
ꢁ
Cu
CuΙΙΙ(CF
3 4
)
P
P
Ph
Ph
2
OCH
3
OCH3
3
6a
7a
Entry Additive
Solvent Time (h) T (℃) Yield[%]
1
2
3
4
5
6
7
8
9
KF
PO
--
DMF
DMF
18
18
18
18
18
18
18
10
18
80
80
80
80
80
80
80
80
50
7
K
3
4
6
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
76
84
55
42
99
50
47
AgF
KI
trifluoromethylation reactions. Furthermore, the reactivity of
ΙΙΙ
ion-pari Cu -CF
3
complexes 3-5 are also in sharp contrast to
Cs CO
2
3
the ion-pair complex 1′ containing phen which is unreactive
toward trifluoromethylation of arylboronic acids.
KF
KF
KF
a
4
0
Table 3 Substrate scope for reaction of 4 with various arylboronic acids
+
a
Reaction conditions: 3 (0.1 mmol), 6a (0.2 mmol), additive (0.2 mmol),
B(OH)
2
CF3
1
9
Ph
P
2
2
Ph
P
2
4
,4′-difluorobiphenyl (0.2 mmol, internal standard, ca -117.0 ppm in
F
Ι
ꢁ
—
1 equiv. AgF
toluene, O
b
5
NMR), solvent (1 mL), under dry O
2
atmosphere. Yields determined by
Cu
CuΙΙΙ(CF3)4
+
1
9
P
P
F NMR spectroscopy relative to 6a.
2
,
Ph
Ph
2
R
80 C, 18 h
o
R
Further examination of additive effect (entries 4-7), such as
AgF, KI, Cs CO and KF shows that addition of KF led to the
7
4
6
2
3
CF
3
quantitative trifluoromethylation of 6a in toluene (entry 7).
AgF also shows some promoting effect, but are less efective
than KF (entry 4). Both the reaction temperature and time are
also important for achieving quantitative yields since reduced
temperature and time led to much lower yields (entries 8,9).
This finding achieves for the first time quantitative
trifluoromethylation of arylboronic acids by isolated ion-pair
CF
3
CF
3
CF3
1
0
H
3
CO
O
7
a, 96% b
7b, 99%
7c, 94%
CF
7d, 96%
CF
3
CF
3
3
CF3
O
NC
1
5
O
O
7i, 99%
O
7j, 99%
7
e, 99%
7s, 88%
I
ΙΙΙ
Cu /Cu trifluoromethyl complexes.
O
CF3
a
Table 2 Substrate scope for reaction of 3 with various arylboronic acids
CF
3
S
+
B(OH)
2
7
o, 70%
7p, 72%
Ph
P
2
Ph2
P
CF
3
Ι
—
1 equiv. KF, toluene
ꢁ
4
Cu
CuΙΙΙ(CF
3
)
+
a
19
P
P
O
, 80 C, 18 h
o
Reaction yields were determined by F NMR spectroscopy using 4,4′-
b
2
Ph
2
Ph
2
R
R
difluorobiphenyl as internal standard (ca -117.0 ppm). Using KF in DMF.
3
6
7
The ligand-dependent coordinating structures and distinct
ΙΙΙ
reactivity propreties of Cu -CF
3
complexes 1-5 as well as 1′
CF
3
CF3
CF
3
CF3
4
5
have important mechanistic implications as to the identity and
reactivity patterns of active catalytic species for oxidative
trifluoromethylation reactions. First, it implies that in the
H
3
CO
O
7
a, 99%
7
c, 99%
CF
7d, 93%
OCH
7
b, 99%
CF
presence of different ancillary ligands, distinct copper CF
3
3
3
3
CF
3
CF
3
intermediates with totally different coordinating structures
may be involved as the active catalytic species (or catalyst
resting state). Second, the distinct reactivity propreties of 3-5
O
O
5
0
O
7i, 99%
O
7j, 99%
7e, 99%
7m, 73%
from that of phen-containing complex 1′ suggest that ancillary
O
CF3
ΙΙΙ
CF
3
ligand has a crucial effect on the reactivity of Cu -CF
3
S
complexes. The structures of complexes 3-5 versus 1′ differ
7
o, 60%
7p, 99%
55 only in the Cu(I) cation with different ancillary ligands.
Therefore, the Cu(I) cation must be responsible for the
differences in reactivity of these complexes. Considering the
fact the reactions of 3-5 with arylboronic acids are benefited
a
19
Reaction yields were determined by F NMR spectroscopy using 4,4′-
difluorobiphenyl as internal standard (ca -117.0 ppm).
2
0
With the optimized reaction conditions identified, we next
examined reaction of 3 with a variety of substituted aryl 60 bisphosphine-ligated Cu (CF ) complexes may probably be
in the nonpolar toluene solvent, this may suggest that neural
ΙΙΙ
3
3
boronic acids 6 with diverse electronic properties (Table 2).
the real active species under the reaction conditions, although
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 3

Dalton Transactions
Page 4 of 6
a
Table 4 Substrate scope for reaction of 5 with various arylboronic acids
acids. The ligand-dependent formation, coordinating
View Article Online
structures and reactivity properties of the N,N-bidentate and
+
DOI: 10.1039/C6DT03016E
B(OH)
2
CF3
ΙΙΙ
PPh
2
Ph P
bisphosphine-containing Cu CF complexes have important
2
3
1
equiv. KF
ΙΙΙ
CuΙ
CuΙΙΙ(CF3)4
ꢁ
—
mechanistic implications that distinct reactive Cu
CF3
O
O
+
toluene, O
80 C, 18 h
2
4
5
species and reaction mechanisms may be involved for
trifluoromethylation reactions using different ancillary ligands.
This study was supported by the National Natural Science
Foundation of China (21472068 and 21202062) and the
Natural Science Foundation of Jiangsu Province (BK2012108).
R
o
R
PPh
2
Ph
2
P
5
6
7
CF
3
CF
3
CF
3
CF3
H
3
CO
O
7d, 57% b
7
a, 82% b
7b, 83%
7c, 55% b
5
0
Notes and references
CF
3
CF
3
CF
3
CF
3
a
The Key Laboratory of Food Colloids and Biotechnology, Ministry of
O
NC
Education, School of Chemical and Material Engineering, Jiangnan
University, Wuxi 214122, Jiangsu Province, China. Fax/Tel: +86-510-
O
O
O
7j, 71%
7e, 90%
7i, 83%
7s, 70%
8
5917763; E-mail: slzhang@jiangnan.edu.cn
O
CF3
CF
3
CF
3
5
6
6
7
7
8
8
9
5
0
5
0
5
0
5
0
† Electronic Supplementary Information (ESI) available: Experimental
details, spectroscopic characterization data. See DOI: 10.1039/b000000x/
CF
3
S
OMe
7m, 48%
Cl
7
o, 47%
7
p, 50%
7q, 94%
1
(a) P. Kirsch, Modern Fluoroorganic Chemistry, Wiley-VCH,
Weinheim, Germany, 2004; (b) S. Purser, P. R. Moore, S. Swallow
and V. V. Gouverneur, Chem. Soc. Rev., 2008, 37, 320; (c) Y. Jiang,
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Chen and G. Liu, Synthesis, 2013, 2919; (f) J. Xu, X. Liu and Y. Fu,
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For examples of copper-promoted trifluoromethylation of aryl and
heteroaryl halides, please refer to ref. 3 and references cited therein.
2
For copper trifluoromethylation of ArB(OH) , see: (a) L. Chu and F.-
L. Qing, Org. Lett., 2010, 12, 5060; (b) T. D. Senecal, A. T. Parsons
and S. L. Buchwald, J. Org. Chem., 2011, 76, 1174; (c) T. Liu and Q.
Shen, Org. Lett., 2011, 13, 2342; (d) J. Xu, D.-F. Luo, B. Xiao, Z.-J.
Liu, T.-J. Gong, Y. Fu and L. Liu, Chem. Commun., 2011, 47, 4300;
a
19
Reaction yields were determined by F NMR spectroscopy using 4,4′-
difluorobiphenyl as internal standard (ca -117.0 ppm). Using AgF.
b
2
the concentrations should be very low. Therefore, a possible
Ι
ΙΙΙ
5
0
5
0
5
0
5
0
mechanistic scheme is that the ion-pair Cu /Cu
complexes constitute the Cu-CF resting state, but the real
active species are the neutral (P )Cu (CF ) species that are
equilibrium with the resting state. Although the concentrations
are low, the high reactivity of these (P )Cu (CF ) complexes
renders the steady conversion of the ion-pair complexes to the
neutral complexes to maintain such an equilibrium (Scheme 3).
However, for complex 1′, the conversion to neutral 1 requires
the presence of additional excess phen which is absent in the
aerobic trifluoromethylation reactions. More, the conditions
CF3
3
ΙΙΙ
2
3 3
3
ΙΙΙ
2
3 3
1
1
2
2
3
3
4
4
5
o
(90 C in HOAc solvent) required for the conversion of 1′ to 1
1
1
as shown in our previous study are also different from the
aerobic trifluoromethylation conditions. Therefore, the
unreactive 1′ should be unable to convert to the active neutral
under the aerobic trifluoromethylation reactions. This may
rationalize the cation effect on the reactivity differences of 3-
versus 1′. Finally, the solvent polarity should impart
significant effects on both the active catalyst forms and their
reactivity properties. Further efforts on the elucidation of the
detailed mechanisms for reaction of both the neutral and ion-
1
(e) C.-P. Zhang, J. Cai, C.-B. Zhou, X.-P. Wang, X. Zheng, Y.-C. Gu
and J.-C. Xiao, Chem. Commun., 2011, 47, 9516; (f) X. Jiang, L. Chu
and F.-L. Qing, J. Org. Chem., 2012, 77, 1251; (g) B. A. Khan, A. E.
Buba and L. J. Goossen, Chem. Eur. J., 2012, 18, 1577; (h) N. D.
Litvinas, P. S. Fier and J. F. Hartwig, Angew. Chem., Int. Ed., 2012,
5
5
1, 536; (i) P. Nova′k, A. Lishchynskyi and V. V. Grushin, Angew.
Chem., Int. Ed., 2012, 51, 7767; (j) Y. Ye and M. S. Sanford, J. Am.
Chem. Soc., 2012, 134, 9034.
ΙΙΙ
pair Cu -CF complexes are desirable to clearly resolve these
3
fundamental issues.
6
Copper-mediated trifluoromethylation of arenes, see: (a) R. Koller, K.
Stanek, D. Stolz, R. Aardoom, K. Niedermann and A. Togni, Angew.
Chem., Int. Ed., 2009, 48, 4332; (b) L. Chu and F.-L. Qing, J. Am.
Chem. Soc., 2012, 134, 1298; (c) R. Shimizu, H. Egami, T. Nagi, J.
Chae, Y. Hamashima and M. Sodeoka, Tetrahedron Lett., 2010, 51,
5947; (d) M. S. Wiehn, E. V. Vinogradova and A. Togni, J. Fluorine
Chem., 2010, 131, 951; (e) S. Cai, C. Chen, Z. Sun and C. Xi, Chem.
Commun., 2013, 49, 4552. For alkene trifluoromethylation reactions,
see: (f) H. Egami and M. Sodeoka, Angew. Chem., Int. Ed., 2014, 53,
Ι
ΙΙΙ
In summary, ion-pair Cu /Cu
containing bisphospine ligands DPPE, BINAP and Xantphos
are efficiently and selectively prepared following a general
and mild method. Complexes 3-5 are composed of
tetrahedral [(bisphosphine)
Cu (CF ) ] . Their strucutres have been well characterized
by H, F, P NMR spectroscopy and X-ray crystallography
3 3
for 3. Under similar conditions neutral (L)Cu (CF )
complexes with N,N-bidentante ligands such as phen and bpy 100
were determined previously. Furthermore, all these ion-pair
complexes 3-5 are highly reactive toward arylboronic acids to
produce trifluoromethylated arenes in up to quantitative yields
under mild conditions. This is also in sharp contrast to the
ion-pair complex 1′ that is unreactive toward arylboronic
CF
3
complexes 3-5
a
Ι +
2
Cu ]
and
a
square planar
95
ΙΙΙ
−
[
3
4
1
19
31
8
293; (g) E. Merino and C. Nevado, Chem. Soc. Rev., 2014, 43, 6598.
ΙΙΙ
Copper-mediated trifluoromethylation of alkynes, see: (h) L. Chu and
F.-L. Qing, J. Am. Chem. Soc., 2010, 132, 7262.
7
8
D. M. Wiemers and D. J. Burton, J. Am. Chem. Soc., 1986, 108, 832.
I
For isolated Cu -CF
3
complexes, see: (a) G. G. Dubinina, H.
Furutachi and D. A. Vicic, J. Am. Chem. Soc., 2008, 130, 8600; (b) G.
G. Dubinina, J. Ogikubo and D. A. Vicic, Organometallics, 2008, 27,
6233; (c) H. Morimoto, T. Tsubogo, N. D. Litvinas and J. F. Hartwig,
Angew. Chem., Int. Ed., 2011, 50, 3793; (d) O. A. Tomashenko, E. C.
1
05
4
|
Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 5 of 6
Dalton Transactions
Escudero-Adan, M. M. Belmonte and V. V. Grushin, Angew. Chem.,
Int. Ed., 2011, 50, 7655; (e) Z. Weng, R. Lee, W. Jia, Y. Yuan, W.
Wang, X. Feng and K.-W. Huang, Organometallics, 2011, 30, 3229;
View Article Online
DOI: 10.1039/C6DT03016E
(f) A. I. Konovalov, J. Benet-Buchholz, E. Martin and V. V. Grushin,
5
Angew. Chem., Int. Ed., 2013, 52, 11637; (g) L. I. Panferova, F. M.
Miloserdov, A. Lishchynskyi, M. M. Belmonte, J. Benet-Buchholz
and V. V. Grushin, Angew. Chem., Int. Ed., 2015, 54, 5218.
9
(a) A. J. Hickman and M. S. Sanford, Nature, 2012, 484, 177; (b) A.
Casitas and X. Ribas, Chem. Sci., 2013, 4, 2301.
III
1
1
2
2
0
5
0
5
10 For Cu -CF
3
complexes, see: (a) M. A. Willert-Porada, D. J. Burton
and N. C. Baenziger, J. Chem. Soc. Chem. Commun., 1989, 1633; (b)
D. Naumann, T. Roy, K.-F. Tebbe and W. Crump, Angew. Chem., Int.
Ed. Engl., 1993, 32, 1482; (c) A. M. Romine, N. Nebra, A. I.
Konovalov, E. Martin, J. Benet-Buchholz and V. V. Grushin, Angew.
Chem., Int. Ed., 2015, 54, 2745; (d) J. A. Schlueter, U. Geiser, J. M.
Williams, J. D. Dudek, D. Naumann, T. Roy, J. E. Schirber and W. R.
Bayless, J. Chem. Soc. Chem. Commun., 1994, 1599.
1
1
1
2
S.-L. Zhang and W.-F. Bie, RSC Adv., 2016, 6, 70902.
(a) E. J. Cho, T. D. Senecal, T. Kinzel, Y. Zhang, D. A. Watson and
S. L. Buchwald, Science, 2010, 328, 1679; (b) E. J. Cho and S. L.
Buchwald, Org. Lett., 2011, 13, 6552; (c) V. V. Grushin and W. J.
Marshall, J. Am. Chem. Soc., 2006, 128, 12644; (d) M. C. Nielsen, K.
J. Bonney and F. Schoenebeck, Angew. Chem., Int. Ed., 2014, 53,
5
903.
13 CCDC 1441928 (3) contains the supplementary crystallographic data
which can be obtained free of charge from Cambridge
Crystallographic Data Centre.
1
4 For detailed reaction procedures, please refer to ESI.†
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 5

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Page 6 of 6
View Article Online
DOI: 10.1039/C6DT03016E
ΙΙΙ
L (1 equiv)
LCu (CF )
3
3
CF SiMe (6 equiv)
3
3
L = N,N-ligands:
phen, bpy
AgF (4 equiv)
CuI
DMF, RT, 18 hours
ArB(OH)2
O2
Ι
+
ΙΙΙ
ꢀ
[
L Cu ] [Cu (CF ) ]
Ar-CF3
2
3 4
This work
L = P,P-ligands:
DPPE, BINAP, Xantphos
excellent
reactivity
I
III
Novel ionꢀpair Cu /Cu trifluoromethyl complexes with representative bisphosphines
III
−
are isolated and fully characterized to feature square planar [Cu (CF
3
)
4
] and
+
tetrahedral [L
2
Cu] units. They show unprecedented excellent reactivity for aerobic
trifluoromethylation of arylboronic acids in generally good to quantitative yields.