Fluorosilane Activation by Pd/Ni→Si-F→Lewis Acid Interaction: An Entry to Catalytic Sila-Negishi Coupling

Article abstract of DOI:10.1021/jacs.0c04690

A new mode of bond activation involving M→Z interactions is disclosed. Coordination to transition metals as σ-Acceptor ligands was found to enable the activation of fluorosilanes, opening the way to the first transition-metal-catalyzed Si-F bond activation. Using phosphines as directing groups, sila-Negishi couplings were developed by combining Pd and Ni complexes with external Lewis acids such as MgBr2. Several key catalytic intermediates have been authenticated spectroscopically and crystallographically. Combined with DFT calculations, all data support cooperative activation of the fluorosilane via Pd/Ni→Si-F→Lewis acid interaction with conversion of the Z-Type fluorosilane ligand into an X-Type silyl moiety.

Full text of DOI:10.1021/jacs.0c04690

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Communication
Fluoro Silane Activation by Pd/Ni#Si#F#Lewis Acid
Interaction: an Entry to Catalytic Sila-Negishi Coupling
Hajime Kameo, Hiroki Yamamoto, Koki Ikeda, Tomohito Isasa, Shigeyoshi Sakaki,
Hiroyuki Matsuzaka, Yago García-Rodeja, Karinne Miqueu, and Didier Bourissou
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.0c04690 • Publication Date (Web): 24 Jul 2020
Downloaded from pubs.acs.org on July 24, 2020
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Fluoro Silane Activation by Pd/Ni→Si‒F→Lewis Acid Interaction:
an Entry to Catalytic Sila-Negishi Coupling
Hajime Kameo,*† Hiroki Yamamoto,† Koki Ikeda,† Tomohito Isasa,† Shigeyoshi Sakaki,§ Hiroyuki
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Matsuzaka,† Yago García-Rodeja,# Karinne Miqueu,# and Didier Bourissou*‡
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†Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho, Naka-ku, Sakai, Osaka
599-8531 Japan
§Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-nishihiraki-cho 34-4, Sakyo-ku Kyoto 606-8103
Japan
#CNRS/Université de Pau et des Pays de l’Adour, Institut des Sciences Analytiques et de Physico-Chimie pour
l’Environnement et les Matériaux, IPREM UMR 5254, Hélioparc, 2 Avenue du Président Angot, 64053 Pau Cedex 09,
France
‡CNRS/Université Toulouse III - Paul Sabatier, Laboratoire Hétérochimie Fondamentale et Appliquée, LHFA UMR 5069,
118 Route de Narbonne, 31062 Toulouse Cedex 09 France
Supporting Information Placeholder
activation (Figure 1D).9,10 In this case, the transition metal acts
ABSTRACT: A new mode of bond activation involving M→Z
as a Lewis base and M→*(Si‒F) donation weakens the Si‒F
bond. Synergistic action of an external Lewis acid was
envisioned to enable bond cleavage and converts the Z-type
fluoro silane ligand into an X-type silyl moiety which may then
be engaged in Si‒C cross-coupling.11 Note that the conversion
of Z-type ligands into X and L-type ligands has been previously
reported by Gabbaï with antimony.12
interactions is disclosed. Coordination to transition metals as
-acceptor ligands was found to enable the activation of fluoro
silanes, opening the way to the first transition metal-catalyzed
Si‒F bond activation. Using phosphines as directing groups,
sila-Negishi couplings were developed by combining Pd and Ni
complexes with external Lewis acids such as MgBr2. Several
key catalytic intermediates have been authenticated
spectroscopically and crystallographically. Combined with
DFT calculations, all data support cooperative activation of the
fluoro silane via Pd/Ni→Si‒F→Lewis acid interaction with
conversion of the Z-type fluoro silane ligand into an X-type silyl
moiety.
[A]
LA
TM
electrophilic TM
• Takaya
• Gabbaï
PPh2
• Inagaki
PPh2
PhB Au
N
Sb Au
F3
Rh
In
Cl
The recent discovery that main-group based Lewis acids are
able to act as -acceptor Z-type ligands for transition metals has
opened new avenues in organometallic chemistry.1 The
resulting MZ interactions offer new ways to tune the
properties of metal centers and the Lewis acid moiety can
actively participate in bond activation via so-called metal-
ligand cooperation.2 To date, Z-type ligands have been mostly
used to modulate the Lewis acidity of electrophilic metal
centers (Figure 1A). This approach has been employed to
activate (C=C) bonds towards cycloisomerization and
nucleophilic addition.3 Recently, it was further extended to C‒H
activation and applied in catalysis to the amidation of arenes
featuring N directing groups.4 Addition of E‒H bonds across
MZ interactions also attracts much interest and offers
interesting perspectives in catalysis (Figure 1B).5,6 Besides the
development of these two scenarios, efforts are made to
discover new modes of cooperation between transition metals
and Lewis acids, such as the one involving hydride insertion
into a PdB interaction we recently reported and applied to the
catalytic hydro/deutero-dechlorination of arenes (Figure 1C).7
PPh2
hydroamination
PPh2
Cl
nitrene insertion
into C-H bonds
cycloisomerization
[B]
[C]
H
E
LA
TM
This work
[D]
LA
LA
TM
H
E = H, C, Si
H
F
Si
TM
H
E
electron flow
LAF and SiTM
LA
LA
TM
TM
• Peters
• Kameo/Bourissou
LA F
Si
TM
B
P
B
Ni
P
Pd
Ph2
Ph2
sila-Negishi coupling
TM = Ni, Pd
PPh3
PPh2
PPh2
hydrogenation
hydro/deutero
dechlorination
Figure 1. Representative modes of bond activation involving
M→Z interactions, with selected examples of complexes applied
in catalysis.
In this work, we reasoned that the ability of fluoro silanes to
coordinate as Z-type ligands8 may open a new approach of bond
Here, we demonstrate the feasibility and catalytic
applicability of such an approach. It enables to achieve for the
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Page 2 of 6
c93% isolated yield.
first time catalytic cross-coupling from fluoro silanes. The use
1
2
3
4
5
6
7
8
of Si-based electrophiles in Si‒C cross-couplings has recently
witnessed an upsurge of interest, and spectacular achievements
have been reported with Si‒I, Si‒OTf and Si‒Cl substrates.13
The activation of Si‒F bonds is more challenging due to their
very high bond strengths.14
Next, the scope of the Pd- and Ni-catalyzed reactions was
explored employing the optimal conditions determined before
(Table 1, Entries 11 and 13).16 As shown in Table 2, very high
conversions were achieved with the fluoro silanes 5 and 6
featuring alkyl substitutents at silicon (R = Me, Et). The
reaction works with a variety of diaryl zinc reagents. It proceeds
smoothly with electron-withdrawing (CF3, F, Cl) as well as
electron-donating substituents (OMe, NMe2), and ortho-
substituents are tolerated. In all cases, very high yields were
observed with 2-4 mol% Pd (>90%). Comparatively, nickel
catalysis was less effective but nevertheless gave the coupling
products in moderate to excellent yields (51-94%), except for
the zinc reagent bearing an o-Me2N substituent.
The known ability of phosphines to support M→Si‒F
interactions8 prompted us to use fluoro silanes 1-2 as substrates
(Table 1). Under typical conditions for Negishi-type coupling,
using ZnPh2, no reaction occurred from 1 (Entry 1). Inspired by
the positive influence of lithium iodide noticed by Ohashi and
Ogoshi in the Pd-catalyzed arylation of tetrafluoroethylene
(C‒F bond activation and coupling with ZnAr2),15 the addition
of various lithium and magnesium salts was tested.16
Gratifyingly, the desired coupling product 3 was formed in 29%
yield in the presence of LiI (Entry 4) and quantitative reactions
were observed using MgBr2 or MgI2 (Entries 7 and 8). The
addition of B(C6F5)3 also enables the catalysis to proceed (Entry
9),17 while no reaction was observed with BPh3 (Entry 10). Even
magnesium salts generated in situ upon formation of ZnPh2 (by
reacting ZnCl2 with PhMgBr) proved efficient (Entry 11).
Nickel catalysis was also possible under the same conditions,
with Ni(cod)2 as precursor. In situ generation of the aryl zinc
species (from ZnCl2 + 2 PhMgBr) and the use of B(C6F5)3 gave
the best result in this case (Entry 13). The diphosphine fluoro
silane 2 was found to undergo Si‒F activation and Si‒Ph
coupling too (Entries 14-17). It is worth noting that the catalysis
worked as well (Pd) or even better (Ni) with only one phosphine
anchoring group. Conversely, no Si−C coupling was observed
starting from Ph3SiF under the same conditions, substantiating
the crucial influence of the phosphine directing groups.
9
10
11
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TABLE 2. Scope of zinc reagents for the sila-Negishi coupling
of fluoro silanes 5-6.a
R
F
R
Ar
R
Si
Si
R
Method A or B
THF, 100 °C, 18 h
PPh2
PPh2
5
6
7-Ar
8-Ar
R = Me
R = Et
Method A: 1 mol% Pd2(dba)3, 3 equiv ZnAr2 (ZnCl2 + 2 ArMgBr)
Method B: 2 mol% Ni(cod)2, 3 equiv ZnAr2 (ZnCl2 + 2 ArMgBr), 2 mol% B(C6F5)3
6
8
R = Et (  )
Ar =
Method A
Method B
97% (96%)
96% (89%)b
95% (91%)b
60%c
94%
91%b
7-Naph
8-Ph
7-Ph
TABLE 1. Screening of conditions for the sila-Negishi coupling
of fluoro silanes 1-2.
MeO
Me2N
Ar =
OMe
Pd(0)a or Ni(0) (2 mol%)
R
F
R
Ph
Ph
Method A
Method B
97% (84%)d
76%c,e
94% (81%)d
93%b
91% (53%)b,d
22%c,e
Si
Si
Zn reagent (2 equiv)
Lewis Acid (1 equiv)
Ph
7-p-Anisyl
7-o-Anisyl
7-(o-Me2N)C6H4
THF, 100 °C, 18 h
F3C
Cl
PPh2
PPh2
1
2
3
4
R = Ph
R = (o-Ph2P)C6H4
Ar =
CF3
F
Method A
Method B
96% (59%)b,d
51%c,e
98% (65%)d
69%c,e
96% (73%)b
80%c,e
Entry
1
Substrate
Catalysta
Zn reagent, LA additive
Yieldb
7-(p-CF3)C6H4
7-(o-CF3)C6H4
7-(3-Cl-4-F)C6H3
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Ni(COD)2
Ni(COD)2
Pd2(dba)3
Pd(PPh3)4
Ni(COD)2
Ni(COD)2
9
ZnPh2, none
ZnPh2, LiCl
0
7
aR = Me (57), unless otherwise stated; spectroscopic yields, as
2
determined by 31P NMR spectroscopy (isolated yields are given in
3
ZnPh2, LiBr
7
b
c
d
parentheses). 5 equiv ZnR2. 10 equiv ZnR2. 2 mol% Pd2(dba)3.
4
ZnPh2, LiI
29
3
e5 mol% Ni(cod)2, 5 mol% B(C6F5)3.
5
ZnPh2, Li(OTf)
ZnPh2, MgCl2
ZnPh2, MgBr2
ZnPh2, MgI2
6
4
To shed light into the involved catalytic cycle and decipher
the way the Si‒F bond is activated, a series of stoichiometric
reactions were performed with the diphosphine fluoro silane 2
(Scheme 1). The two coordinating arms were hoped to stabilize
some reactive intermediates and facilitate their characterization.
First, complex 9 was obtained in excellent yield (91%) by
phosphine exchange from Pd(PPh3)4.16 As shown by X-ray
diffraction analysis (Figure 2a), the Pd center adopts a
tetrahedral arrangement with the fluoro silane moiety
coordinated via weak Pd∙∙∙Si and Pd∙∙∙Cipso contacts.18 Most
diagnostic are the relatively short Pd‒Si distance [2.9770(8) Å,
as to compared with the sum of van der Waals radii at 4.15 Å19],
the elongation of the Si‒F bond [1.6339(17) vs 1.606(2) Å in
{(o-Ph2P)C6H4}3SiF] and the trigonal pyramidal environment
around Si [the sum of C‒Si‒C angles = 352.36(21)°, PdSi‒F
7
99
99
82
0
99c
65
96
97
76
25
21
66
84
8
9
ZnPh2, B(C6F5)3
ZnPh2, BPh3
ZnCl2 + 2 PhMgBr
ZnCl2 + 2 PhMgBr
10
11
12
13
14
15
16
17
18
19
ZnCl2
B(C F )
ZnCl2 + 2 PhMgBr
ZnCl2 + 2 PhMgBr
ZnCl2 + 2 PhMgBr
+
2
PhMgBr,
PhMgBr,
ZnCl2
B(C F )
ZnCl2 + 2 PhMgBr
+
2
11Pd-Br
ZnCl2 + 2 PhMgBr
a1 mol% catalyst for Pd2(dba)3. bDetermined by 31P NMR.
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BPh4 anion and hydrogen atoms are omitted, the phenyl groups at
P and Si are simplified for clarity.
bond angle = 161.67(8)°]. The presence of substantial PdSi‒F
interaction in 9 was further supported by 29Si NMR
spectroscopy20 and DFT calculations.16
1
2
3
4
5
6
7
8
Not surprisingly, related Ni species were more difficult to
study. A complex akin to 9 could be detected by NMR
spectroscopy upon reacting 2 with Ni(COD)2 in the presence of
DMAP.16 The feasibility and easiness of Si‒F cleavage by
cooperation between nickel and Lewis acids could also be
substantiated. Indeed, addition of lithium or magnesium salts to
a 1:1 mixture of 2 and Ni(COD)2 resulted in the fast and
selective formation of the corresponding (diphosphine-
silyl)(halogeno)nickel(II) complexes 11Ni-X (X = Cl, Br, I). The
structure and square-planar arrangement of complex 11Ni-Cl
were confirmed crystallographically (Figure 2d).16
Remarkably, addition of LiX (X = Cl, Br, I) and MgX2 (X =
Cl, Br) salts at room temperature spontaneously induced Si‒F
bond cleavage and afforded the corresponding square-planar
(diphosphine-silyl)(halogeno)palladium(II) complexes 11Pd-X
(X = Cl, Br, I), all authenticated crystallographically (Figure
21
2b).16 Similarly, reacting 9 with the boranes BF3 and B(C6F5)3
at room temperature rapidly and cleanly led to the cationic silyl
complex [(PSiP)Pd(PPh3)][FBX3] 10a,b, whose structure was
authenticated by X-ray diffraction after counter-anion exchange
(complex 10c, Figure 2c, BPh4 salt). Of note, complexes 11Pd-
Cl and 10c readily react with MgBr2 to afford 11Pd-Br, making
the latter complex a likely intermediate of the catalytic
coupling. Interestingly, the conversion between the Z-type
fluoro silane and X-type silyl moieties is reversible. Treatment
of 11Pd-Br with tetrabutylammonium fluoride (TBAF) in the
presence of PPh3 regenerated the silane complex 9.
9
10
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The Si‒F bond cleavage at Pd / Ni assisted by BF3 was
studied computationally.16 The key structures are depicted in
Figure 3 for Pd. The Si‒F bond significantly elongates upon
interaction with BF3 (from 1.693 to 2.012 Å) while the Pd‒Si
distance substantially shortens (from 2.770 to 2.490 Å).
Ultimately, BF3 abstracts the fluoride. The electron flow
associated with the M→Si‒F→BF3 interaction is clearly
apparent from the NBO analyses16 and the intrinsic bond
orbitals (IBOs). The Pdsilane dative interaction turns into a
covalent Pd‒silyl bond while the (Si‒F) bond evolves into a
(B‒F) bond. Despite the strength of the Si‒F bond, the
concomitant participation of Pd / Ni and BF3 makes its cleavage
very easy, with an activation barrier of only 3–5 kcal/mol.16
BF3 or
F
B(C6F5)3
Ph
Si
Si
Ph
PPh2
[FBR3]
PPh2
TBAF
Pd
Pd
Ph2P
Ph2P
9
PPh3
PPh3
L
i
X
o
10a,b
R = F, C6F5
r
M
T
B
g
A
X
Pd(PPh3)4
F
2
,
P
P
h
3
PPh2
Ph
F
F
Ni(cod)2
LiX or MgX2
B
Ph
Si
F
Si
F
BF4
Si
Pd
PPh3
F
PPh2
M
F
Ph
Si
Ph
PPh2
Ph2P
PPh2
Si
X
Ph
PPh2
PPh2
11M-X
Pd
2
Ph2P
Ph2P
M = Ni, Pd
X = Cl, Br, I
Pd
ZnPh2 or
Zn(C6F5)2
Ph2P
10a
PPh3
9
PPh3
WBI
PPh2
Ph
d
WBI
d
d
WBI
0.45
0.08
0.59
2 
,
Ph
Si
M
Ar
Pd‒Si
Si‒F
F‒B
2.770
1.693
-
0.22
0.49
-
2.490
2.012
1.561
0.38
0.24
0.46
2.405
2.670
1.460
Si
PPh2
Ph
Ar = Ph
Ph2P
PPh2
12M-Ar
4
M = Ni, Pd
Ar = Ph, C6F5
Scheme 1. Pd and Ni complexes deriving from the diphosphine
fluoro silane 2.
Pd‒Si
(a)
(b)
Si‒F/F‒B
Figure 3. Key structures computed for the Si‒F bond cleavage
mediated by Pd and BF3. Selected distances (in Å), Wiberg
bond indexes (WBI) and intrinsic bond orbitals (IBOs).16
(d)
The transmetalation and reductive elimination steps were
studied then. Complex 11Pd-Br was found to react smoothly
with ZnPh2 to give the corresponding phenyl complex
(PSiP)Pd(Ph) 12Pd-Ph, obtained as a 2:1 mixture with 11Pd-Br
using 10 equiv. of ZnPh2 (1:3 ratio with 3 equiv. of ZnPh2). The
structure of the analogous pentafluorophenyl complex 12Pd-
C6F5 prepared with Zn(C6F5)2 was unambiguously
authenticated by X-ray diffraction analysis.16 The nickel
complex 11Ni-Br also readily undergoes transmetalation when
reacted with 10 equiv. of ZnPh2. The phenyl complex
(PSiP)Ni(Ph) 12Ni-Ph was obtained quantitatively in this case.16
(c)
Figure 2. Molecular structures of complexes 9 (a), 11Pd-Br (b), 10c
(c) and 11Ni-Cl (d). Thermal ellipsoids at 40% probability. The
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Finally, thermolysis of both complexes 12Pd-Ph and 12Ni-Ph at
Page 4 of 6
1
2
3
4
5
6
7
8
60-80 °C in the presence of 2 afforded the Si‒Ph coupling
product 4 within 2-16 hours. In line with the rather forcing
conditions required to achieve these reductive eliminations
(compared to the Si‒F bond cleavage), the activation barriers
computed by DFT are relatively large (20-23 kcal/mol).16
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the ACS
Publications website.
Based on all experimental and computational data, the sila-
Negishi coupling is proposed to occur following the 4-step
catalytic cycle disclosed in Figure 4 for the diphosphine fluoro
silane 2: (i) P-directed coordination of the fluoro-silane to Pd as
a -acceptor ligand, (ii) Si‒F bond cleavage by cooperation
between Pd and the Lewis acid, (iii) transmetalation by ZnPh2;
(iv) reductive elimination and ligand exchange at Pd to release
the coupling product 4 and turnover. Of note, the isolated Pd
Experimental methods and DFT calculations (PDF)
Crystallographic data (CIF)
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10
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AUTHOR INFORMATION
Corresponding Author
h.kameo@c.s.osakafu-u.ac.jp
dbouriss@chimie.ups-tlse.fr
complexes
9
and 11Pd-Br showed catalytic activities
comparable to Pd(PPh3)4 (Table 1, Entries 18-19), supporting
their relevance. In addition, direct transmetalation from Zn to
Si, once the fluoro-silane is coordinated to Pd as a Z-type
ligand, seems unlikely. Indeed, no reaction was observed
between complex 9 and ZnPh2. The presence of a Lewis acid
ACKNOWLEDGMENT
This work was supported by Grant-in-Aid for Scientific Research
(C) (No. 18K05151 and 18K05152) of the Ministry of Education,
Culture, Sports, Science and Technology (MEXT), Japan. H.K.
acknowledges the financial support from the Tonen general sekiyu
research/development encouragement & scholarship foundation.
The Centre National de la Recherche Scientifique (CNRS), the
Université Paul Sabatier (UPS) and the Agence Nationale de la
Recherche (ANR-15-CE07-0003) are acknowledged for financial
support of this work. The "Direction du Numérique" of the
Université de Pau et des Pays de l'Adour and CINES under
allocation A007080045 made by Grand Equipement National de
Calcul Intensif (GENCI) are acknowledged for computational
facilities.
and activation of the Si‒F bond are required. Note also that 31
P
NMR monitoring a catalytic reaction performed with the fluoro
silane 2 as substrate and Pd(PPh3)4 as catalyst (reaction
conditions of entry 15, Table 1) showed the presence of
complexes 11Pd-Br and 12Pd-Ph in about 3:1 ratio as resting
states.
Pd(PPh3)4
3 PPh3
+
MgBr2
2
(i)
F
(ii)
Ph
Si
Pd
Br
Si
Ph
PPh2
PPh2
Pd
Ph2P
Ph2P
11Pd-Br
9
PPh3
REFERENCES
PPh2
(1) (a) Amgoune, A.; Bourissou, D. -Acceptor, Z-type Ligands for
Transition Metals. Chem. Commun. 2011, 47, 859–871. (b) Bouhadir, G.;
Bourissou, D. Coordination of Lewis Acids to Transition Metals: Z-type
Ligands. In the Structure and Bonding book entitled “The Chemical Bond
III - 100 years old and getting stronger” (Ed.: Mingos, D. M. P.) 2017, 171,
pp. 141‒201.
(iii)
ZnPh2
Ph
Ph
Si
(iv)
PPh2
Ph
Si
4
2
+ PPh3
PPh2
12Pd-Ph
Pd
Ph
Ph2P
(2) (a) Bouhadir, G.; Bourissou, D. Complexes of Ambiphilic Ligands:
Reactivity and Catalytic Applications. Chem. Soc. Rev. 2016, 45,
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S.; Bouhadir, G.; Slootweg, J. C.; Uhl, W.; Bourissou, D. Novel
Zwitterionic Complexes Arising from the Coordination of an Ambiphilic
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Promoting Enyne Cyclizations Angew. Chem. Int. Ed. 2015, 54, 818–822.
(c) Yang, H.; Gabbaï, F. P. Activation of a Hydroamination Gold Catalyst
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Chem. Soc. 2015, 137, 13425–13432. (d) You, D.; Gabbai, F. P. Activation
of a Hydroamination Gold Catalyst by Oxidation of a Redox-Noninnocent
Chlorostibine Z-Ligand J. Am. Chem. Soc. 2017, 139, 6843‒6846. (e)
Cammarota, R. C.; Vollmer, M. V.; Xie, J.; Ye, J.; Linehan, J. C.; Burgess,
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Complex Catalyzes CO2 Hydrogenation via the Intermediacy of an Anionic
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Figure 4. Plausible catalytic cycle for the Si‒F bond activation
/ arylation of 2 co-catalyzed by Pd(PPh3)4 and MgBr2 (as
representative examples).
In conclusion, the coordination of fluoro silanes as -
acceptor ligands was shown to enable Si‒F bond activation
under mild conditions. When combined with external Lewis
acids such as MgBr2, palladium and nickel are able to readily
cleave Si‒F bonds thanks to Pd/NiSi‒FLA interactions.
The process was turned to catalysis and sila-Negishi cross-
coupling starting from fluoro silanes was actually achieved for
the first time. The activation of Si‒F bonds is of major interest
because many transformations involving silicon derivatives end
in fluoro silanes (the strength of the Si‒F bond being used as a
driving force). Developing catalytic Si‒C cross-couplings from
fluoro silanes may enable to recycle Si by-products and
contribute to circular silicon chemistry.22
(4) Yamada, R.; Iwasawa, N.; Takaya, J. Rhodium-Catalyzed C-H
Activation Enabled by an Indium Metalloligand. Angew. Chem. Int. Ed.
2019, 58, 17251‒17254.
(5) (a) Harman, W. H.; Peters, J. C. Reversible H2 Addition across a
Nickel-borane Unit as a Promising Strategy for Catalysis. J. Am. Chem. Soc.
2012, 134, 5080–5082. (b) Harman, W. H.; Lin, T.-P.; Peters, J. C. A d10
The new mode of activation evidenced here for Si‒F bonds
expands further the chemistry arising from MZ interactions
and may be generalized to other directing groups and other
strong polar bonds.
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Ni–(H2) Adduct as an Intermediate in H‒H Oxidative Addition across a
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6638. (b) Kirai, N.; Takaya, J.; Iwasawa, N. Two Reversible σ‑Bond
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Mediated Reversible -Hydrogen Elimination and Hydrometalation at
Palladium Chem. Eur. J. 2014, 20, 1181 –11819. (d) Kim, J.; Kim, Y.-E.;
Park, K.; Lee, Y. A Silyl-Nickel Moiety as a Metal–Ligand Cooperative
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(12) (a) Ke, I.‐S.; Jones, J. S.; Gabbaï, F. P. Anion-Controlled Switching
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J. S.; Wade, C. R.; Gabbaï, F. P. Redox and Anion Exchange Chemistry of
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Single Element. Angew. Chem. Int. Ed. 2014, 53, 8876–8879.
Ni‒B Bond. Angew. Chem. Int. Ed. 2014, 53, 1081–1086. (c) MacMillan,
S. N.; Harman, W. H.; Peters, J. C. Facile Si–H Bond Activation and
Hydrosilylation Catalysis Mediated by a Nickel–borane Complex. Chem.
Sci. 2014, 5, 590–597. (d) Cowie, B. E.; Emslie, D. J. H. Platinum
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2
3
4
5
6
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8
Complexes
of
a
Borane-Appended
Analogue
of
1,1’-
Bis(diphenylphosphino)ferrocene: Flexible Borane Coordination Modes
and in situ Vinylborane Formation. Chem. Eur. J. 2014, 20, 16899–16912.
(e) Barnett, B. R.; Moore, C. E.; Rheingold, A. L.; Figueroa, J. S.
Cooperative Transition Metal/Lewis Acid Bond-Activation Reactions by a
Bidentate (Boryl)iminomethane Complex: A Significant Metal–Borane
Interaction Promoted by a Small Bite-Angle LZ Chelate. J. Am. Chem. Soc.
2014, 136, 10262–10265. (f) Devillard, M.; Declercq, R.; Nicolas, E.;
Ehlers, A. W.; Backs, J.; Saffon-Merceron, N.; Bouhadir, G.; Slootweg, J.
C.; Uhl, W.; Bourissou, D. A Significant but Constrained Geometry PtAl
Interaction: Fixation of CO2 and CS2, Activation of H2 and PhCONH2. J.
Am. Chem. Soc. 2016, 138, 4917–4926. (g) Li, Y.; Hou, C.; Jiang, J.; Zhang,
Z.; Zhao, C.; Page, A. J.; Ke, Z. General H2 Activation Modes for Lewis
Acid-Transition Metal Bifunctional Catalysts. ACS Catal. 2016, 6, 1655–
1662. (h) Cammarota, R. C.; Lu, C. C. Tuning Nickel with Lewis Acidic
Group 13 Metalloligands for Catalytic Olefin Hydrogenation. J. Am. Chem.
Soc. 2015, 137, 12486–12489. (i) Ramirez, B. L.; Lu, C. C. Rare-Earth
Supported Nickel Catalysts for Alkyne Semihydrogenation: Chemo- and
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Am. Chem. Soc. 2020, 142, 5396−5407.
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Transition Metals and Lewis Acids: a New Way to Activate H2 and H–E
bonds. Angew. Chem. Int. Ed. 2015, 54, 730–732.
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Palladium-Borane Cooperation: Evidence for an Anionic Pathway and its
Application to Catalytic Hydro- / Deutero-dechlorination. Angew. Chem.
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9
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2653‒2656. (c) McAtee, J. R.; Martin, S. E. S.; Ahneman, D. T.; Johnson,
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‐Catalyzed Silylation of Terminal Olefins: A Silyl-Heck
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Catalyzed Cross-Coupling of Silyl Electrophiles with Alkylzinc Halides: A
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(14) Bond dissociation energies for R3Si‒F bonds > 150 kcal/mol, see Y.-
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CRC press, 2002.
(15) Ohashi, M.; Kambara, T.; Hatanaka, T.; Saijo, H.; Doi, R.; Ogoshi,
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(16) See Supporting Information for details.
(17) Abstraction of the fluoride at Si was supported in this case by the
characterization of the fluoroborate [FB(C6F5)3]‒ upon monitoring the
reaction by 19F{1H} NMR spectroscopy (Figure S1A).16
(18) Analogous 2-coordination is known for aryl-boranes, see: Emslie,
D. J. H.; Cowie, B. E.; Kolpin, K. B. Acyclic Boron-Containing -Ligand
Complexes: 2- and 3-Coordination Modes. Dalton Trans. 2012, 41,
1101–1117.
(10) For stoichiometric activations of B‒F, P‒F, Sb‒F bonds at transition
metals involving Z-type coordination, see: (a) Bauer, J.; Braunschweig, H.;
Kraft, K.; Radacki, K. Oxidative Addition of Boron Trifluoride to a
Transition Metal Angew. Chem. Int. Ed. 2011, 50, 10457‒10460. (b) Bauer,
J.; Braunschweig, H.; Dewhurst, R. D.; Radacki, K. Reactivity of Lewis
Basic Platinum Complexes Towards Fluoroboranes Chem. Eur. J. 2013, 19,
8797–8805. (c) Arnold, N.; Bertermann, R.; Bickelhaupt, F. M.;
Braunschweig, H.; Drisch, M.; Finze, M.; Hupp, F.; Poater, J.; Sprenger, J.
A. P. Formation of a Trifluorophosphane Platinum(II) Complex by P−F
Bond Activation of Phosphorus Pentafluoride with a Pt0 Complex. Chem.
Eur. J. 2017, 23, 5948‒5952. (d) You, D.; Yang, H.; Sen, S.; Gabbaï, F. P.
Modulating the σ-Accepting Properties of an Antimony Z-type Ligand via
Anion Abstraction: Remote-Controlled Reactivity of the Coordinated
Platinum Atom. J. Am. Chem. Soc. 2018, 140, 9644‒9651.
(19) Batsanov, S. S. Van der Waals Radii of Elements. Inorg. Mater.
2001, 37, 871‒885.
(20) The 29Si NMR signal is shifted to higher field and the JSi-F coupling
constant is reduced upon coordination of 2 to Pd, in line with that reported
previously for related gold complexes.8a,b
(21) For fluoride abstraction from a PtSb‒F complex with B(C6F5)3,
see ref. 10d.
(22) (a) Withers, P. J. A.; Elser, J. J.; Hilton, J.; Ohtake, H.; J. Schipper,
W. J.; van Dijk, K. C. Greening the Global Phosphorus Cycle: How Green
Chemistry can Help Achieve Planetary P Sustainability. Green Chem. 2015,
17, 2087‒2099. (b) Keijer, T.; Bakker. V.; Slootweg, J. C. Circular
Chemistry to Enable a Circular Economy. Nat. Chem. 2019, 11, 190‒195.
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Table of Contents artwork
1
2
3
4
5
6
F
R1
R2
Ar
R1
R2
Pd(0) or
Ni(0) cat.
Si
Si
+
ZnAr2
7
8
MgBr2
PR2
PR2
9
R1
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
LA
F
 MSi−FLA electron flow
R2
Si
 M / LA cooperation for easy Si−F activation
 from Z-type fluoro silane to X-type silyl
 catalytic Si−F arylation
M
P
R2
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