Non-Metal-Catalyzed Heterodehydrocoupling of Phosphines and Hydrosilanes: Mechanistic Studies of B(C6F5)3-Mediated Formation of P-Si Bonds

Article abstract of DOI:10.1021/jacs.7b09175

Non-metal-catalyzed heterodehydrocoupling of primary and secondary phosphines (R¹R²PH, R² = H or R¹) with hydrosilanes (R³R⁴R⁵SiH, R⁴, R⁵ = H or R³) to produce synthetically useful silylphosphines (R¹R²P-SiR³R⁴R⁵) has been achieved using B(C₆F₅)₃ as the catalyst (10 mol %, 100 °C). Kinetic studies demonstrated that the reaction is first-order in hydrosilane and B(C₆F₅)₃ but zero-order in phosphine. Control experiments, DFT calculations, and DOSY NMR studies suggest that a R¹R²HP·B(C₆F₅)₃ adduct is initially formed and undergoes partial dissociation to form an "encounter complex". The latter mediates frustrated Lewis pair type Si-H bond activation of the silane substrates. We also found that B(C₆F₅)₃ catalyzes the homodehydrocoupling of primary phosphines to form cyclic phosphine rings and the first example of a non-metal-catalyzed hydrosilylation of P-P bonds to produce silylphosphines (R¹R²P-SiR³R⁴R⁵). Moreover, the introduction of PhCN to the reactions involving secondary phosphines with hydrosilanes allowed the heterodehydrocoupling reaction to proceed efficiently under much milder conditions (1.0 mol % B(C₆F₅)₃ at 25 °C). Mechanistic studies, as well as DFT calculations, revealed that PhCN plays a key mechanistic role in facilitating the dehydrocoupling reactions rather than simply functioning as H₂-acceptor.

Full text of DOI:10.1021/jacs.7b09175

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Article
Non-Metal Catalysed Heterodehydrocoupling of
Phosphines and Hydrosilanes: Mechanistic Studies
of B(C6F5)3-Mediated Formation of P-Si Bonds
Lipeng Wu, Saurabh S. Chitnis, Haijun Jiao, Vincent T. Annibale, and Ian Manners
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.7b09175 • Publication Date (Web): 09 Oct 2017
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Non-Metal Catalysed Heterodehydrocoupling of Phosphines
and Hydrosilanes: Mechanistic Studies of B(C6F5)3-Mediated
Formation of P-Si Bonds
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Lipeng Wu,& Saurabh S. Chitnis,& Haijun Jiao,# Vincent T. Annibale,& and Ian Manners*,&
&School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
#Leibniz-Institut für Katalyse e. V. Albert-Einstein-Straße 29a, 18059 Rostock, Germany
ABSTRACT: Non-metal catalysed heterodehydrocoupling of primary and secondary phosphines (R1R2PH, R2 = H or R1)
with hydrosilanes (R3R4R5SiH, R4, R5 = H or R3) to produce synthetically useful silylphosphanes (R1R2P-SiR3R4R5) has been
o
achieved using B(C6F5)3 as the catalyst (10 mol%, 100 C). Kinetic studies demonstrated that the reaction is first-order in
hydrosilane and B(C6F5)3 but zero-order in phosphine. Control experiments, DFT calculations as well as DOSY NMR stud-
ies suggest that a R1R2HP•B(C6F5)3 adduct is initially formed and which subsequently undergoes partial dissociation to
form an “encounter complex”. The latter mediates Frustrated Lewis Pair-type Si-H bond activation of the silane sub-
strates. We also found that B(C6F5)3 catalyses the homodehydrocoupling of primary phosphines to form cyclic phosphine
rings and the first example of a non-metal catalysed hydrosilylation of P-P bonds to produce silylphosphanes (R1R2P-
SiR3R4R5). Moreover, the introduction of PhCN to the reactions involving secondary phosphines with hydrosilanes al-
lowed the heterodehydrocoupling reaction to proceed efficiently under much milder conditions (1.0 mol% B(C6F5)3 at 25
°C). Mechanistic studies, as well as DFT calculations, revealed that PhCN plays a key mechanistic role in facilitating the
dehydrocoupling reactions rather than simply functioning as H2-acceptor.
(Scheme 1, D).20 Complexation of cyclic silylphosphanes
INTRODUCTION
Molecular and macromolecular species containing
with transition metal centers has also been reported
(Scheme 1, E).21
bonds between main-group elements (E-E') (E = p-block
element) represent attractive synthetic targets due to
their interesting reactivity and useful properties.1-15 For
example, main group polymers containing Si-O,8 Si-N,14
Si-Si,15 or P=N6-7 bonds in the main chain and related ma-
terials have found applications as elastomers, lithographic
resists, biomaterials, polyelectrolytes, ceramic precursors,
optoelectronics, and several other materials are of explor-
atory interest.3-5, 9-13 As the second most abundant element
in the earth’s crust, silicon introduces useful functionality
and transformations, the construction of Si-E bonds has
received considerable attention. However, compared with
the large number of well-known species containing Si-O
or Si-N bonds, compounds containing P-Si bonds (si-
lylphosphanes) have received much less attention.16
Silylphosphanes have considerable potential utility in
chemical synthesis, for example, as silyl cation equiva-
lents in the silylation of alcohols (Scheme 1, A);17 through
their reaction with acid chlorides to yield acylphosphides
(Scheme 1, B)18 and their palladium-catalysed reaction
with aryl halides to produce aryl(diphenyl)phosphines
(Scheme 1, C).19 Very recently, Miura and Hirano reported
the diphosphination of alkenes using silylphosphanes to
Scheme 1. Transformations of silylphosphanes and com-
afford
dppe-type
(dppe
=
1,2-
plexation with transition metals species.
bis(diphenylphosphino)ethane)
bidentate
ligands
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Traditionally, silylphosphanes have been prepared by dition of B(C6F5)3 even at 130 °C (Table 1, entry 1). Further
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the reaction of chlorosilanes with alkali metal phospha-
nides, a process that generates at least one equivalent of
salt waste and has limited functional group tolerance.16, 22
The recent expansion in catalytic dehydrocoupling meth-
ods has provided a much milder and general route to
form E-E' bonds.23-29 Surprisingly, the catalytic heterode-
hydrocoupling of phosphines (R1R2PH) with hydrosilanes
(R3R4R5SiH, R4, R5 = H or R3) has only been reported using
titanocene for secondary phosphines30 (Scheme 2, equa-
tion 1) or triamidoamine-supported zirconium complexes
for primary phosphines31 (Scheme 2, equation 2), and the
reactions were limited to primary and secondary silanes.
Significantly, the synthetically useful silylphosphanes il-
lustrated in Scheme 1 are all derived from tertiary silanes.
As part of our interest in catalytic reactions of main group
substrates we have explored the development of new
catalytic dehydrocoupling routes to silylphosphanes.
Here, we chose the well-known Lewis acid B(C6F5)3
(tris(pentafluorophenyl)borane) as the catalyst for this
transformation.32-34 The B(C6F5)3-mediated activation of
Si-H bonds has been well-studied in the pioneering work
by Piers34-41 and more recently by Ostreich,42-45 Chang46-48
and others in the context of hydrosilylation of C=X (X = O
and NR)37, 44, 49-52 and C≡N47-48 containing substrates as
experiments showed that this reaction was sensitive to
temperature: at 80 °C after 16 h only 50% of 1a was con-
sumed albeit with 100% selectivity to 3a (Table 1, entry 4).
The reaction conditions were optimized with 10 mol%
B(C6F5)3, at 100 °C for 16 h in benzene to give 95% conver-
sion of 1a and 98% selectivity for 3a (Table 1, entry 5).
After completion the 19F NMR spectrum of the reaction
mixture showed two major species that were identified as
being the adducts of B(C6F5)3 with either 1a or 3a.57-58 No
signals due to Piers’ borane (HB(C6F5)2)59 or adducts
thereof were observed. Higher temperature (130 °C) or
catalyst loading (20 mol%) produced more of 4a (Table 1,
entries 6 and 8).
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Table 1. B(C6F5)3-catalysed heterodehydrocoupling of
PhPH2 with Et3SiH – effect of catalyst loading and tem-
perature. a
Entries
x
T
[°C]
Conversion
[%]b
Selectivity
[%]b
[mol%]
well as in the dehydrocoupling of silanes with –OH,36, 53
–
3a
-
4a
NHR54 and aromatic C-H bonds.55 Surprisingly, the relat-
ed dehydrocoupling of phosphines R1R2PH with hy-
drosilanes using B(C6F5)3 or any other non-metal species
has not been reported. Herein, we report the first non-
metal catalysed heterodehydrocoupling of primary and
secondary phosphines (R1R2PH, R2 = H or R1) with prima-
ry, secondary, and tertiary hydrosilanes (R3R4R5SiH, R4, R5
= H or R3).
1
0
10
10
10
10
10
2
130
25
0
0
-
-
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-
50
3
100
100
98
80
100
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0
0
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80
50
95
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99
100
130
100
100
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0
7
20
aPhPH2 (0.1 mmol, 11 µl), Et3SiH (0.3 mmol, 48 µl),
B(C6F5)3 (0.1x mmol), benzene 0.5 mL in J. Young NMR
b
tube, 16 h; determined by 31P NMR spectroscopy using a
sealed capillary of PCl3 as an integration standard.
Scheme 2. Previous work on the transition-metal-
catalysed heterodehydrocoupling of phosphines with hy-
drosilanes.
RESULTS AND DISCUSSION
Conditions optimization: We first examined the reac-
tion between PhPH2 (1a) and Et3SiH (2a) in the presence
of catalytic amounts of various Lewis acids
([Ph3C][B(C6F5)4], AgNO3, Zn(OAc)2), carbene (IMes) or
combinations of B(C6F5)3 with different bulky Lewis bases
(P(tBu)3, 2,6-di-tert-butylpyridine - DTBP) to form typical
Frustrated Lewis Pairs (FLPs)56 (Table S1). We found that
B(C6F5)3 alone gave superior results and produced mono-
silylation product 3a and bis-silylation product 4a. It is
worth noting that no reaction took place without the ad-
Figure 1. Time-dependent 31P{1H} NMR spectra of the
B(C6F5)3 (0.01 mmol) catalysed heterodehydrocoupling of
PhPH2 (1a, 0.1 mmol) with Et3SiH (2a, 0.3 mmol) in 0.5 mL
benzene at 100 °C.
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0.45
0.4
0.1
0.08
0.06
0.04
0.02
0
0.35
0.3
0.25
0.2
0.15
0.1
0.05
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0
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200
Time (Min)
Time [Min]
0.0004
0.00035
0.0003
0.00025
0.0002
0.00015
0.0001
0.00005
0
0.00025
0.0002
0.00015
0.0001
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0.015
0.02
0.025
0.03
0.035
[Silane] [M]
[Cat] [M]
Figure 2. Kinetic studies of B(C6F5)3-catalyzed heterodehydrocoupling of PhPH2 with Et3SiH: (A) Decay of PhPH2 during the
reaction at 100 °C with the release of H2 every 20 min; (B) Zero-order reaction rate in PhPH2, (initial concentration of PhPH2:
blue line 0.05 M, orange line 0.1 M, purple line 0.4 M); (C) First-order reaction rate in Et3SiH; (D) First-order reaction rate in
B(C6F5)3.
Although 1a has two potentially reactive P-H bonds, we
found that the reaction did not yield more than 8% of the
bis-silylation product 4a even after 120 h at 100 °C. Moni-
Under pseudo-first order conditions generated using
excess 2a (8-60 fold), we varied the concentration of 1a
from 0.05 M to 0.1 M and 0.4 M and obtained same kobs
which indicated a zero-order reaction rate in 1a (Figure
2B). This implied that 1a was not involved in the rate de-
termining step. The reaction order in 2a was determined
using 1.5 – 12 equivalents of 2a with respect to 1a, with the
concentration of 1a = 0.1 M, and that of B(C6F5)3 = 0.01 M
at 100 °C. A linear correlation between kobs and [2a] (R2 =
0.9924) revealed a first-order dependence of the reaction
on the concentration of 2a (Figure 2C). Changing the
concentration of B(C6F5)3 and keeping the concentration
of 1a at 0.2 M and 2a at 0.6 M, a plot of kobs versus the
concentration of B(C6F5)3 also yielded a straight line (R2 =
0.9986) that passed through the origin, in accordance
with a first-order reaction in B(C6F5)3 (Figure 2D).
31
toring the reaction by P NMR spectroscopy showed that
4a did not appear until 90% of 1a had been consumed
(Figure 1), which implies that the mono-silylation product
3a is much less reactive than 1a. This could be attributed
to the enhanced steric and/or changed electron density
on the phosphorus atom. By heating the reaction to 130 °C
for 48 h, we could obtain 4a with 78% selectivity together
with 14% of the homodehydrocoupling product from 1a
and minor amount of an unassigned product. This finding
is in agreement with the computed thermodynamics: the
formation of 3a (1a + 2a = 3a + H2) is only marginally ex-
ergonic (ΔG = -0.33 kcal/mol) and slightly favoured ther-
modynamically. However, the formation of 4a (3a + 2a =
4a + H2) is endergonic (ΔG = 3.73 kcal/mol) and is not
favoured thermodynamically.
As the reaction was found to be first-order in silane,
deuterium-labelling experiments using Et3SiD (2a') were
performed to gain further insight into the reaction mech-
anism. Using standard reaction conditions determined in
Table 1, entry 5 (0.2 M 1a and 0.6 M 2a' with 0.02 M
B(C6F5)3, in benzene at 100 °C), we were surprised to find
that H/D-scrambling was detected by 31P NMR spectros-
copy (characterized by the appearance of the PhPHD tri-
plet at -124.7 ppm with a J(P−D) spin−spin coupling con-
stant of 31.8 Hz and PhPD2 quintet at -125.8 ppm) (Figure
3A). In addition, we could also observe H2 and HD (char-
acterized by the appearance of the HD triplet at 4.44 ppm
with a J(H−D) spin−spin coupling constant of 42.7 Hz in
the 1H NMR spectrum) (Figure 3B). Nevertheless, we were
Kinetic studies and isotope labelling experiments:
While monitoring the B(C6F5)3-mediated reaction of
PhPH2 (1a) and Et3SiH (2a) in benzene we found that the
reaction rate was constant for the first 100 min (Figure S1),
which motivated detailed kinetic studies. The initial reac-
tion rate was recorded to avoid the possible reverse hy-
drogenation reaction. In fact, we found that the reaction
rate did not change with H2 ventilation every 20 mins
compared to a closed system and we could still detect the
deviation from the constant reaction rate after 100 mins
(Figure 2A).
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Figure 3. Deuterium labelling experiments: (A) 31P{1H} NMR spectrum of the reaction PhPH2 0.2 M, Et3SiD 0.6 M, and 0.02 M
1
B(C6F5)3 in 0.5 mL benzene after 4 h at 100 °C; (B) H NMR spectrum of the reaction PhPH2 0.2 M, Et3SiD 0.6 M, and 0.02 M
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B(C6F5)3 in 0.5 mL benzene after 10 h at 100 °C; (C) B NMR spectrum of the reaction PhPH2 0.2 M, Et3SiH 0.6 M, and 0.02 M
B(C6F5)3 in 0.5 mL benzene before heating; (D) 11B NMR spectrum of the reaction PhPH2 0.2 M, Et3SiD 0.6 M, and 0.02 M
B(C6F5)3 in 0.5 mL benzene before heating.
able to run the deuterium-labelling experiments at a
lower catalyst loading (0.01 M, 5 mol%) while keeping the
concentration of other reactants the same and halting the
reaction before the H/D-scrambling was observed (100
min). This led to the determination of a kinetic isotope
effect 1.5. Isotope effects of 1.4-1.9 have been reported for
the hydrosilylation of carbonyl compounds and were in-
terpreted in terms of hydride transfer.37, 60 Additional ex-
periments showed that the H/D-scrambling did not take
place in the absence of B(C6F5)3 or when the temperature
was reduced to 25 °C. This observation together with the
fact that we could detect [HB(C6F5)3]− and [DB(C6F5)3]− at
room temperature (Figure 3C-D) support the assertion
that hydride transfer was involved in the rate determining
step. Based on these observations, and that formation of
[HB(C6F5)3]− only occurs in the presence of phosphine 1a,
we propose that both 1a and deuterated hydrosilane 2a'
are each activated by B(C6F5)3 with the assistance of Lewis
base (1a) at high temperature to generate [HB(C6F5)3]−
and [DB(C6F5)3]− (Scheme 3, equations 1-3), followed by
anion exchange (Scheme 3, equation 4) which eventually
gives the H/D-scrambling products PhPHD and Et3SiH
(Scheme 3, equation 5). We discuss further evidence to
support B(C6F5)3–mediated activation of 1a in the follow-
ing section.
Scheme 3. Proposed reaction pathway for the H/D-
scrambling of PhPH2 with Et3SiD.
B(C6F5)3-catalyzed homodehydrocoupling of PhPH2
and hydrosilylation of P-P bonds. As our kinetic stud-
ies and deuterium labelling experiments suggested that
PhPH2 (1a) was activated by B(C6F5)3, and since previous
work by Stephan and co-workers has demonstrated the
catalytic homodehydrocoupling of 1a with B(p-C6F4H)3 at
130 °C to give cyclophosphines, (PhP)5,61 we considered
the possibility that homodehydrocoupling products from
1a were formed initially, followed by B(C6F5)3-catalyzed
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hydrosilylation of the skeletal P-P bonds62 to produce the
silylphosphane (Scheme 4). To test our hypothesis, the
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reaction was repeated without 2a but under otherwise
identical conditions (0.2 M 1a and 0.02 M B(C6F5)3 in 0.5
mL benzene), we found that no reaction took place at 100
°C after 16 h. However, on raising the reaction tempera-
ture to 130 °C we observed the homodehydrocoupling of
1a. Monitoring the reaction showed that the (PhPH)2 and
a mixture of cyclic phosphine products (PhP)x (x = 4-6)
were produced initially and eventually all converted to
the cyclic products, predominantly (PhP)5 (89% selectivi-
ty) (Figure 4). The computed homodehydrocoupling of
PhPH2 [2PhPH2 = PhPH-PHPh + H2] is slightly endergonic
(ΔG = 0.84 kcal/mol) and such endergonic characteristics
explain the need of higher temperature experimentally.
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Figure 5. Time-dependent 31P{1H} NMR spectra of B(C6F5)3-
catalysed hydrosilylation of phosphine rings: (PhP)4-6 (0.02
mmol, cal. 10.8 mg), Et3SiH (0.3 mmol, 48 µl), B(C6F5)3 (0.01
mmol) in 0.5 mL benzene in a J. Young NMR tube at 130 °C. a
Selectivity was calculated as a sum of 4a + 5a (where 5a is the
adduct PhP(SiEt3)2•B(C6F5)3).
Scheme 4. Proposed reaction pathway involving ho-
modehydrocoupling of 1a with subsequent hydrosilylation
of the P-P bonds.
Figure 4. Time-dependent 31P{1H} NMR spectra of B(C6F5)3-
catalyzed homodehydrocoupling of 1a: B(C6F5)3 (0.01 mmol),
1a (0.1 mmol) in 0.5 mL benzene at 130 °C.
Figure 6. Time-dependent 31P{1H} NMR spectra of B(C6F5)3-
catalysed hydrosilylation of tetraphenylbiphosphine 6a:
(Ph2P)2 (0.05 mmol, 18.5 mg), Et3SiH (0.3 mmol, 48 µl),
B(C6F5)3 (0.01 mmol), benzene 0.5 mL in a J. Young NMR
tube, 130 °C.
Next, we explored the catalytic hydrosilylation of the
isolated phosphine rings (91% (PhP)5) with 3 equivalents
2a and 10 mol% B(C6F5)3. Once again, under our catalytic
conditions (100 °C, 16 h) no reaction was detected and
heating to 130 °C was necessary for the hydrosilylation of
P-P bonds to take place. After 200 h, 96% conversion was
achieved, with the mono-silylation product 3a formed
with 43% and the bis-silylation product 4a with 45% se-
lectivity (Figure 5). We also found that the reaction
worked as well for the isolated (PnHex)5 rings (Figure S5).
In contrast, catalytic hydrosilylation of the bulkier cyclic
phosphines (PtBu)4 or (PtBu)3 was unsuccessful. The hy-
drosilylation of tetraphenyldiphosphine (6a), on the other
hand, gave rise to 45% silylation product 8a together with
14% diphenylphosphine (7a) and other unidentified side
products which indicated that some of the silylation
product arises from the dehydrocoupling of the silane
with 7a generated by the hydrosilylation (Figure 6).
From these experiments, we concluded that although
the reaction pathway described in Scheme 4 is feasible, it
is not operative in our catalytic reaction since the
B(C6F5)3-catalysed homodehydrocoupling of 1a requires a
higher temperature (130 °C vs 100 °C) and a longer reac-
tion time (120 h vs 16 h). In addition, the similar distribu-
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tion of mono- and bis-silylphosphane products 3a (43%)
Page 6 of 13
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and 4a (45%) observed in the catalytic hydrosilylation of
the skeletal P-P bonds of the (PhP)X rings and the higher
temperature required (130 °C) further ruled out the path-
way in Scheme 4 as a possibility in our catalytic experi-
ments. Nevertheless, our experiments represent the first
examples of B(C6F5)3-catalyzed homodehydrocoupling of
phenylphosphine as well as the first catalytic hydrosilyla-
tion of P-P bonds (Scheme 4).
9
The phosphine-borane adduct PhH2P•B(C6F5)3 as a
thermally generated FLP catalyst: The observed zero-
order reaction in PhPH2 prompted us to investigate an-
other possible reaction pathway involving an intermedi-
ate adduct derived from PhPH2 and B(C6F5)3. DFT calcula-
tions show that PhPH2 (1a) and B(C6F5)3 can form a stable
complex PhH2P•B(C6F5)3 (9a) based on the computed ex-
ergonic (ΔG = -7.53 kcal/mol). In contrast, the formation
of the complex Et3Si-H•B(C6F5)3 between Et3SiH (2a) and
B(C6F5)3 is endergonic (ΔG = 5.85 kcal/mol) and not fa-
voured thermodynamically. Furthermore, we failed to
optimize a stable complex Et3Si-H•PH2Ph between 1a and
2a. This shows that 9a should be one of the principal in-
termediates in the reaction. Since the loading of B(C6F5)3
is only 10% of the concentration of 1a, the formation 9a
explains the zero-order dependence of [1a] and the first
order dependence of [B(C6F5)3]. That 2a cannot form sta-
ble complexes with B(C6F5)3 and 1a also explains the first
order dependence of 2a. In addition, we computed the
adducts of 3a and 4a with B(C6F5)3. It was found that that
formation of 3a•B(C6F5)3 and 4a•B(C6F5)3 is exergonic by
10.64 and 3.90 kcal/mol, respectively. 3a Coordinates
more strongly to B(C6F5)3 than 1a is consistent with the
kinetic behaviour in Figure 2A after 100 min, where 1a is
liberated from B(C6F5)3 by the subsequently formed 3a.
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Scheme 5. Synthesis of PhH2P•B(C6F5)3 adduct and its
catalytic and stoichiometric reaction with Et3SiH: (A)
PhPH2 (1 mmol, 110 µl), B(C6F5)3 (1 mmol, 510 mg), ben-
zene 10 mL 25 °C; (B) PhPH2 (0.1 mmol, 11 µl), Et3SiH (0.3
mmol, 48 µl), PhH2P•B(C6F5)3 (0.01 mmol, 6.22 mg), ben-
zene 0.5 mL in J. Young NMR tube, 100 °C, 16 h; (C)
PhH2P•B(C6F5)3 (0.02 mmol, 12.4 mg), Et3SiH (0.06 mmol,
9.6 µl), benzene 0.5 mL in J. Young NMR tube, 16 h.
interactions that activates the Si-H before dissociation to
form free PhPH2 and B(C6F5)3 (Scheme 6).34, 63-64
Diffusion-Ordered Spectroscopy (DOSY) NMR studies
were conducted to detect the potential dissociation of
PhH2P•B(C6F5)3 adduct (9a) and further understand the
nature of the interactions (Figure S9-12).63 At a concentra-
tion of 0.04 M in benzene at 25 °C, we found that 1a pos-
sesses a diffusion coefficient (D) of 17.0 x 10−10 m2 s−1 and
for B(C6F5)3 a value of 7.1 x 10−10 m2 s−1. DOSY NMR analysis
of a solution of 0.04 M 9a in benzene gave values of D =
6.3 x 10−10 m2 s−1 and 5.1 x 10−10 m2 s−1 for PhPH2 and
B(C6F5)3, respectively. The smaller diffusion coefficients in
both cases compared to the separate species indicated an
interaction in solution consistent with our variable tem-
perature 31P NMR spectroscopy studies (Scheme S7).
To obtain more insights into the reaction mechanism, a
series of stoichiometric reactions were carried out. Upon
mixing equimolar amounts of 1a and B(C6F5)3 in benzene
we found the formation of 9a in quantitative yield (triplet
at -48.0 ppm with a J(P−H) = 423 Hz).57 Furthermore, we
found that 9a is very stable even at 100 °C, and neither
free phenylphosphine (1a) nor B(C6F5)3 was observed in a
high temperature NMR experiment (Figure S7). We thus
considered whether 9a is directly involved in the catalytic
cycle. To explore this possibility, 9a was isolated as a
white solid and used as the catalyst (10 mol%) for the het-
erodehydrocoupling of 1a and 2a at 100 °C. Significantly,
we observed a similar reaction yield and selectivity to 3a
(Scheme 5B). We were also interested to explore whether
9a was reactive towards Et3SiH in the absence of 1a. Our
experiments indeed demonstrated that 9a reacts readily
with Et3SiH in benzene and that this yields
PhP(H)SiEt3•B(C6F5)3 (10a) in high yield at 100 °C over 16 h
(Scheme 5C, Figure S8). Furthermore, the reaction also
worked at 25 °C, albeit with a significantly reduced reac-
tion rate (Scheme 5C). These results suggest that 9a is
involved in the Si-H bond activation in our catalytic reac-
tion. We propose that the process involves an “encounter
complex” generated from the 9a via secondary
Scheme 6. Formation of a classical Lewis acid/base ad-
duct and dissociation to form the “encounter complex”
and activatation of the Si-H bond.
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Table 2. B(C6F5)3-catalysed heterodehydrocoupling of PhPH2 with different hydrosilanes.a
1
2
3
4
5
6
7
8
9
Entries hydrosilanes
1
Time [h]
16
T [°C]
100
Products
Yields [%]b
93 (89)c
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
3a
3b
3c
3d
2a
2
16
16
100
100
76
77
2b
3
2c
4
16
130
100
91
2d
5
36
92 (85)
2e
3e
6
4
8
130
130
54
2f
3f
7
62 (55)
2g
3g:3g' = 4:1
aPhPH2 (0.1 mmol, 11 µl), hydrosilanes (0.3 mmol, 48 µl), B(C6F5)3 (0.01 mmol), benzene 0.5 mL in J. Young NMR tube,
100-130 °C; bdetermined by 31P NMR spectroscopy using a sealed capillary of PCl3 as an integration standard; isolated
c
yields.
On the other hand, the different values for the two
species (6.3 x 10−10 m2 s−1 vs 5.1 x 10−10 m2 s−1) using 9a
indicated that the P-B interaction is dynamic with the
equilibrium highly favouring 9a.
studied over the past decade in cases where the Lewis
acid and base do not form a classical adduct.56, 65 When
B(C6F5)3 is used with oxygen- or nitrogen-containing
compounds (e.g. alcohols, amines, imines) as bases and
reactants, labile Lewis acid/base adduct formation is
generally observed prior to subsequent reactivity (e.g.
The activation of E-H bonds using B(C6F5)3/bulky
phosphine via FLP-type combinations has been well-
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Page 8 of 13
imine reduction with H2, dehydrocoupling of hydrosilanes
B(C6F5)3-catalyzed heterodehydrocoupling of sec-
with alcohols).36, 64, 66 Our system represents the first case
for phosphines where a classical Lewis acid/base adduct
(9a) is observed and can be isolated prior to its thermally-
ondary phosphines with Et3SiH in the presence of
PhCN. When we attempted to extend the B(C6F5)3-
catalysed heterodehydrocoupling chemistry to the sec-
ondary phosphine, Ph2PH (7a) with Et3SiH (2a) in ben-
zene, we found that the reaction proceeded very slowly.
Even with 20 mol% B(C6F5)3 at 100 °C, only 10% of the
heterodehydrocoupling product 8a was produced after 16
h. Heating the reaction to 130 °C for 48 h increased the
yield of 8a to ca. 60%. Analysis of the reaction mixture by
31P NMR spectroscopy revealed the appearance of multi-
ple peaks around -24.4 ppm which might arise from the
thermal rearrangement of the adduct Ph2HP•B(C6F5)3.68
This was further confirmed via the independent reaction
of equimolar amounts of Ph2PH and B(C6F5)3 at 130 °C for
24 h (Figure S13). Compared with the formation of
PhH2P•B(C6F5)3 (ΔG = -7.53 kcal/mol), the formation of
Ph2HP•B(C6F5)3 is even more exergonic (ΔG = -9.38
kcal/mol), indicating that Ph2HP•B(C6F5)3 is more stable
than PhH2P•B(C6F5)3 by 1.85 kcal/mol. In addition, the
formation of 8a [7a + 2a = 8a + H2] is computed to be en-
dergonic by 1.64 kcal/mol and therefore thermodynami-
cally not favoured thus rationalizing the need of high
temperature.
1
2
3
4
5
6
7
8
induced concerted reaction with
a third substrate
(Et3SiH). The observed reaction of the thermally stable
adduct PhH2P•B(C6F5)3 with Et3SiH, the zero-order
reaction in PhPH2, and DOSY NMR studies indicate that
the rupture of the P-B dative bond to form an “encounter
complex” is responsible for the Si-H activation and in this
manner is analogous to the activations of H-H and Sn-H
bonds using FLPs (e.g. B(C6F5)3/Mes3P) (Scheme 6).34, 67
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Synthesis of different silylphosphanes. After
establishing the mechanism for the B(C6F5)3-catalysed
heterodehydrocoupling between 1a with 2a, hydrosilanes
with different substituents were applied to study the
generality of our strategy (Table 2). We found that
hydrosilanes 2b and 2c with small substituents on silicon
gave the products 3b and 3c with yields 76% and 77%,
respectively. Bulky silanes such as triphenylsilane 2d led
to a much lower reaction rate and required higher
temperature (130 °C) to produce the corresponding
silylphosphane 3d in good yield (91%). 1,4-
Bis(dimethylsilyl)benzene 2e reacted with 1a at 100 °C
after 36 h produce the cyclic product 3e in very good yield
(92%). Moreover, when using secondary silanes 2f or
primary silane 2g, 6 and 4-membered rings 3f-3g were
obtained at 130 °C with moderate yield (54-62%). The
structures of 3e and 3g were confirmed by single-crystal
X-ray diffraction as shown in Figure 7.
In order to obtain a higher yield of 8a, we attempted to
avoid the side reaction involved Ph2HP•B(C6F5)3 by lower-
ing the reaction temperature. Stephan69 and Oestreich70
have previously introduced alkenes as H2-acceptors to
allow the homodehydrocoupling reactions of phosphines
and heterodehydrocoupling of aromatic C-H and B-H
bonds to take place under milder conditions. Adopting
this strategy, we explored the addition of different poten-
tial H2-acceptors to the reaction of 7a with 2a. Initially,
we added different alkenes, unfortunately, cyclohexene, 1-
octene, and 1, 1-diphenylethylene all failed to affect the
reaction rate. Other types of H2-acceptor such as phenyla-
cetylene, benzophenone, nitrobenzene, azobenzene also
failed as H2-acceptors (Table S2). Remarkably, we found
that by using PhCN as the H2-acceptor we could obtain 8a
in 99% yield within 20 min at 25°C (Scheme 7). This is a
dramatic acceleration effect and allowed the reaction to
be performed with only 1 mol% catalyst loading and still
gave 99% yield at 25°C, furthermore, with even 0.5 mol%
catalyst loading at 50 °C the reaction was essentially com-
plete in 3 h with 99% yield (Table S3).
Figure 7. Molecular structures of 3e and 3g determined by
single-crystal X-ray Diffraction. For 3e non-hydrogen atoms
shown as 30% probability ellipsoids and all H-atoms are
omitted for clarity, the molecule possesses a crystallograph-
ically imposed inversion centre in the middle of the ring. For
3g non-hydrogen atoms are shown as 30% probability ellip-
soids, and H atoms bound to Si are shown as spheres of arbi-
trary radius. All other H atoms, and the second component
of the disordered central 6-membered [Si-P]3 ring are omit-
ted for clarity.
Scheme 7. PhCN accelerated B(C6F5)3-catalyzed heter-
odehydrocoupling of Ph2PH with Et3SiH: Ph2PH (0.1
mmol, 17.4 µl), Et3SiH (0.3 mmol, 48 µl), PhCN (0.1 mmol,
10.3 µl), B(C6F5)3 (0.01 mmol), 0.5 mL benzene in a J.
Young NMR tube, 20 min, 25 °C.
The dramatic acceleration effect of PhCN suggested
that rather than simply functioning as an H2-acceptor, a
new reaction pathway may be operative. We therefore
carried out competitive binding experiments to explore
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We then carried out a kinetic study by monitoring the
the role of PhCN. As shown in Figure 8, combining 7a and
1
2
3
4
5
6
7
8
B(C6F5)3 gave rise to the classical adduct. Addition of 1
equiv. of PhCN to the adduct and monitoring the reaction
by 31P NMR spectroscopy after 1 h showed 40% free Ph2PH
which indicated 60% Ph2HP•B(C6F5)3 adduct and 40%
PhCN•B(C6F5)3 adduct (11B NMR, -12.6 ppm) existed(Figure
8 and S14). These ratios give a Keq of 0.44 for the dis-
placement of the phosphine from Ph2HP•B(C6F5)3 by
PhCN, indicating that the binding of the phosphine to
B(C6F5)3 is 0.5 kcal mol-1 more favorable. Indeed, this val-
ue is in excellent agreement with our calculation that
Ph2PH binding to B(C6F5)3 is 0.6 kcal mol-1 more favorable
than PhCN (Scheme 8).
reaction of 0.1 mmol 7a, 0.3 mmol 2a and 0.1 mmol PhCN
with 2.5 mol% B(C6F5)3 at 25 °C using 31P NMR spectrosco-
py. We observed two new peaks at 15.7 ppm (int1) and 7.7
ppm (int2) after 30 min. The intensity of these peaks in-
creased initially and decreased after 120 min before com-
plete conversion to 8a (Figure 9). The absence of those
two peaks when no PhCN is present and the reaction pro-
file of the reaction with PhCN suggested that they repre-
sent intermediates arising from reactions involving PhCN.
As we have demonstrated binding of both Ph2PH and
PhCN to B(C6F5)3 and since it is known that hydrosilyla-
tion of PhCN can produce imines or amines (Scheme 9,
equation 1),48 we proposed that one of the intermediates
might be a silylimine that undergoes hydrophosphination
with 7a (Scheme 9, equation 2).
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Ph2PH
Ph2HP B(C6F5)3
C
B
A
To test our hypothesis, the corresponding stepwise re-
actions were conducted (Scheme 9). First, the hydrosilyla-
tion of PhCN by Et3SiH in the presence of B(C6F5)3 was
conducted yielding the imine 11a as the only product at 25
°C. Only after heating at above 50 °C, the saturated silyl-
amine (11b) could be detected (Scheme 9, equation 1). As
a control experiment no hydrosilylation occured without
B(C6F5)3. Then the reaction between 11a and 7a was tested
and again we found no reaction in the absence of B(C6F5)3.
However, upon addition of 10 mol% B(C6F5)3 a new peak
appeared at 7.7 ppm (int2 in catalytic experiments) in the
31P NMR spectrum within 5 min. The species giving rise to
this signal was isolated and identified as the silylimine
hydrophosphination product 12a (Scheme 9, equation 2).
Finally, reaction of 12a with 2a gave rise to the dehydro-
coupling product 8a (Scheme 9, equation 3). These step-
wise experiments confirmed our hypothesis that PhCN
functions as a precursor to 11a which undergoes hydro-
phosphination with 7a to produce 12a, the latter species
subsequently reacts with 2a to give the final product.
B(C6F5)3
15 10
5
0
-5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65
f1 (ppm)
Figure 8. 31P{1H} NMR spectra of competitive binding
experiments of Ph2PH and PhCN with B(C6F5)3: (A) Ph2PH
(0.01 mmol, 1.7 µl), benzene 0.5 mL in a J. Young NMR
tube, 25 °C; (B) after addition of B(C6F5)3 (0.01 mmol, 5.1
mg); (C) 1 h after addition of PhCN (0.01 mmol, 1.1 µl).
Ph2PH
+
B(C6F5)3
Ph2HP B(C6F5)3
ꢀG = − 9.38 kcal/mol
PhCN
+
B(C6F5)3
PhCN B(C6F5)3
ꢀG = − 8.78 kcal/mol
Ph2PH
+
PhCN B(C6F5)3
Ph2HP B(C6F5)3
+
PhCN
SiEt3
SiEt3
10 mol%
Ph
N
ꢀ
−
Ph
N
G = 0.6 kcal/mol
(1)
PhCN
+
Et3SiH
SiEt3
benzene
25 °C, 120 min
2a
11b
11a
heat at 50 °C
PPh2
quantitative yield
Scheme 8. Thermodynamics of Ph2PH and PhCN binding
to B(C6F5)3.
B(C6F5)3
10 mol%
(2)
SiEt3
SiEt3
N
Ph
N
Ph
+
Ph2PH
H
benzene
11a
7a
25 °C, 5 min
12a
quantitative yield
B(C6F5)3
10 mol%
PPh2
SiEt3
SiEt3
SiEt3
Ph
N
H
(3)
+
Et3SiH
+
Ph
N
H
P
benzene
25 °C, 30 min
Ph
Ph
12 a
2a
8a 99%
13a
Scheme 9. The stepwise reaction of the B(C6F5)3-
catalyzed heterodehydrocoupling of Ph2PH with Et3SiH in
the presence of PhCN: (1) PhCN (0.1 mmol, 10.3 µl), Et3SiH
(0.3 mmol, 48 µl), B(C6F5)3 (0.01 mmol), benzene 0.5 mL in
J. Young NMR tube, 25 °C; (2) 11a (0.1 mmol, 22 µl), Ph2PH
(0.1 mmol, 17.4 µl), B(C6F5)3 (0.01 mmol), benzene 0.5 mL
in J. Young NMR tube, 25 °C; (3) 12a (0.1 mmol, 40.5 mg),
Et3SiH (0.2 mmol, 32 µl), B(C6F5)3 (0.01 mmol), benzene
0.5 mL in J. Young NMR tube, 25 °C.
Figure 9. Reaction profile of B(C6F5)3-catalyzed heterodehy-
drocoupling of Ph2PH with Et3SiH in the presence of PhCN:
Ph2PH (0.1 mmol, 17.4 µl), Et3SiH (0.3 mmol, 48 µl), B(C6F5)3
(0.0025 mmol), PhCN (0.1 mmol, 10.3 µl), benzene 0.5 mL in
J. Young NMR tube, 25 °C.
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Figure 10. Energy profile (kcal/mol) for the B(C6F5)3-
catalyzed heterodehydrocoupling of Ph2PH with Et3SiH with
and without PhCN.
Figure 11. 11B NMR spectra of the reactions: (A) Ph2PH 0.1
Although no peak at 15.7 ppm (int 1) was observed in the-
se control experiments, we tentatively assign it to be the
further dehydrocoupling product from the –NH of 12a
with 2a.
mmol, B(C6F5)3 0.025 mmol in 0.5 mL benzene at 25 °C; (B)
after addition of 0.1 mmol PhCN to A at 25 °C; (C) addition of
0.3 mmol Et3SiH to B and monitor after 30 min; (D) addition
of 0.3 mmol Et3SiH to B and monitor after 12 h.
We performed DFT calculations to assess the viability
of the proposed reaction pathway (Figure 10). Hydrosilyla-
tion of the PhCN with Et3SiH is exergonic with ΔG = -9.59
kcal·mol−1 and further hydrophosphination with Ph2PH is
also exergonic with ΔG = −6.28 kcal·mol−1, this are con-
sistent with our experimental results (Scheme 9, equa-
tions 1-2). The final step, surprisingly, is even more exer-
gonic with a value of ΔG = −7.30 kcal·mol−1 and confirms
again that the presence of PhCN allows the reaction to be
performed under substantially milder conditions and with
shorter reaction times. The PhCN free system, on the oth-
er hand, is endergonic by 1.64 kcal·mol−1 (Figure 10). This
calculation is in line with our experimental findings that
without PhCN higher temperatures are needed for the
dehydrocoupling of phosphine with hydrosilane to take
place.
11
by B NMR throughout the reaction (Figure 11) supports
the FLP mechanism.
CONCLUSION
The first non-metal catalysed heterodehydrocouplings
of phosphines (R1R2PH, R2 = H or R1) with primary, sec-
ondary, and tertiary hydrosilanes (R3R4R5SiH, R4, R5 = H
or R3) to produce synthetically useful silylphosphanes
(R1R2P-SiR3R4R5) has been achieved using B(C6F5)3. De-
tailed mechanistic studies (kinetic studies, variable tem-
perature NMR spectroscopy) have shown that the reac-
tion relies on the key Lewis acid/base adduct,
R1R2HP•B(C6F5)3. Under the reaction conditions this clas-
sical Lewis adduct functions as a precursor to a thermally
generated FLP to activate Si-H bonds and enable heter-
odehydrogenative P-Si coupling. Through DOSY NMR
spectroscopy experiments we have shown that the inter-
action of phosphines with B(C6F5)3 is dynamic and leads
to the formation of an “encounter complex” which is re-
sponsible for the reactivity. We have also demonstrated
the B(C6F5)3-catalysed homodehydrocoupling of phos-
phines to produce cyclic phosphine rings and the first
non-metal catalytic hydrosilylation of P-P bonds. Moreo-
ver, we have successfully introduced PhCN in the reaction
of secondary phosphines Ph2PH with Et3SiH to avoid the
thermal rearrangement side products from the
Ph2HP•B(C6F5)3 adduct and this allows the reaction to
take place under much milder conditions (100 °C reduced
to 25 °C and catalyst loading from 10 mol% to 0.5 mol%).
Control experiments have revealed that PhCN is involved
in the formation of key intermediate (12a), which will
react with hydrosilanes to give the final heterodehydro-
coupling products via an FLP-type activation. The excel-
lent agreement between calculated and experimental
thermodynamics provides a convincing rationalization of
the experimental results.
11
We also followed the reaction using B NMR spectros-
copy in order to further understand the mechanism and
the fate of B(C6F5)3 (Figure 11). We found that by adding
Et3SiH to a solution containing Ph2PH, PhCN, and
B(C6F5)3 the anion [HB(C6F5)3]- was formed and persisted
throughout the reaction (Figure 11C). After the reaction
was complete, we could also observe the accumulation of
the [HB(C6F5)3]- (Figure 11D), which might arise from the
activation of excess amount of Et3SiH in the presence of
phosphines or amines.
Compound 12a could interact with Et3SiH to yield
product 8a via two different mechanisms: a) σ-bond me-
tathesis of the Si-H bond with the C-P bond from 12a,
which has previously been proposed30,31 or b) coordination
of 12a with B(C6F5)3 either through the P or N atom or
both to form a frustrated “encounter complex” capable of
activating the Si-H bond and forming an ionic intermedi-
ate 14a. The latter species could undergo hydride attack at
the carbon of the C-P bond of 12a to form the product 8a
and release amine 13a (Figure 12). The σ-bond exchange
mechanism features a symmetry forbidden metathesis
reaction and the fact that we could observe [HB(C6F5)3]-
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Figure 12. Proposed reaction mechanism for the reaction of 12a to 8a: left, sigma-bond metathesis route; right, FLP route.
Owen. M. J.; Smith, S. D., Eds. ACS Symposium Series; American
Chemical Society: Washington, DC, 2000.
ASSOCIATED CONTENT
9.
R.; Manners, I., Chem. Soc. Rev. 2016, 45, 5358-5407.
10. Schäfer, A.; Jurca, T.; Turner, J.; Vance, J. R.; Lee, K.;
Du, V. A.; Haddow, M. F.; Whittell, G. R.; Manners, I., Angew.
Chem. Int. Ed. 2015, 54, 4836-4841.
Hailes, R. L. N.; Oliver, A. M.; Gwyther, J.; Whittell, G.
Supporting Information. Experimental details, products
characterizations, computational chemistry, crystallographic
data for 3e and 3g, this material is available free of charge via
the Internet at http://pubs.acs.org.
11.
Priegert, A. M.; Rawe, B. W.; Serin, S. C.; Gates, D. P.,
AUTHOR INFORMATION
Chem. Soc. Rev. 2016, 45, 922-953.
Corresponding Author
12.
Greenberg, S.; Stephan, D. W., Chem. Soc. Rev. 2008,
37, 1482-1489.
*ian.manners@bristol.ac.uk
13.
Staubitz, A.; Sloan, M. E.; Robertson, A. P. M.; Frie-
drich, A.; Schneider, S.; Gates, P. J.; Günne, J. S. a. d.; Manners, I.,
Notes
J. Am. Chem. Soc. 2010, 132, 13332-13345.
The authors declare no competing financial interest.
14.
Birot, M.; Pillot, J.-P.; Dunogues, J., Chem. Rev. 1995,
95, 1443-1477.
ACKNOWLEDGMENT
15.
16.
17.
Miller, R. D.; Michl, J., Chem. Rev. 1989, 89, 1359-1410.
Fritz, G.; Scheer, P., Chem. Rev. 2000, 100, 3341-3402.
Hayashi, M.; Matsuura, Y.; Watanabe, Y., Tetrahedron
L.W. and V.T.A. are grateful to the European Union for Marie
Curie Fellowships (H2020-MSCA-IF-2015_701972 and H2020-
MSCA-IF-2016_748371). S.S.C. and V.T.A. acknowledge the
Government of Canada for the award of a Banting Postdoc-
toral Fellowship and an NSERC Postdoctoral fellowship re-
spectively. We would like to thank Dr. Craig Butts and Paul
Lawrence for their input on the DOSY experiments and Dr.
Hazel A. Sparkes for help with X-ray crystallography.
Lett. 2004, 45, 1409-1411.
18.
106, 177-187.
19.
753.
20.
Ed. 2016, 55, 13558-13561.
Becher, H. J.; Fenske, D.; Langer, E., Chem. Ber. 1973,
Tunney, S. E.; Stille, J. K., J. Org. Chem. 1987, 52, 748-
Okugawa, Y.; Hirano, K.; Miura, M., Angew. Chem. Int.
21.
Driess, M.; Reisgys, M.; Pritzkow, H., Angew. Chem.
REFERENCES
Int. Ed. 1992, 31, 1510-1513.
22.
23.
Fritz, G., Adv. Inorg. Chem. 1987, 31, 171–214.
Gauvin, F.; Harrod, J. F.; Woo, H. G., Adv. Organomet.
1.
Donath, M.; Hennersdorf, F.; Weigand, J. J., Chem. Soc.
Rev. 2016, 45, 1145-1172.
Chem. 1998, 42, 363–405.
2.
3.
Manners, I., Angew. Chem. Int. Ed. 1996, 35, 1602-1621.
Imori, T.; Lu, V.; Cai, H.; Tilley, T. D., J. Am. Chem. Soc.
24.
Less, R. J.; Melen, R. L.; Naseri, V.; Wright, D. S., Chem.
Commun. 2009, 45, 4929-4937.
1995, 117, 9931-9940.
25.
26.
Waterman, R., Chem. Soc. Rev. 2013, 42, 5629-5641.
Leitao, E. M.; Jurca, T.; Manners, I., Nat. Chem. 2013, 5,
4.
5.
Cheng, F.; Jakle, F., Polym. Chem. 2011, 2, 2122-2132.
Nunns, A.; Gwyther, J.; Manners, I., Polymer 2013, 54,
817-829.
27.
1269-1284.
Melen, R. L., Chem. Soc. Rev. 2016, 45, 775-788.
6.
Allcock, H. R., Dalton Trans. 2016, 45, 1856-1862.
28.
Marquardt, C.; Jurca, T.; Schwan, K.-C.; Stauber, A.; Vi-
7.
Rothemund, S.; Teasdale, I., Chem. Soc. Rev. 2016, 45,
rovets, A. V.; Whittell, G. R.; Manners, I.; Scheer, M., Angew.
Chem. Int. Ed. 2015, 54, 13782-13786.
5200-5215.
8.
Mark, J. E., Overview of Siloxane Polymers. In Silicones
and Silicone-Modified Materials, Clarson, S. J.; Fitzgerald. J. J.;
11
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 12 of 13
29.
Johnson, H. C.; Leitao, E. M.; Whittell, G. R.; Manners,
50.
51.
Ren, X.; Du, H., J. Am. Chem. Soc. 2016, 138, 810-813.
Lipke, M. C.; Liberman-Martin, A. L.; Tilley, T. D., An-
1
2
3
4
5
6
7
8
I.; Lloyd-Jones, G. C.; Weller, A. S., J. Am. Chem. Soc. 2014, 136,
9078-9093.
gew. Chem. Int. Ed. 2017, 56, 2260-2294.
52. Chong, C. C.; Hirao, H.; Kinjo, R., Angew. Chem. Int.
Ed. 2015, 54, 190-194.
30.
J. Am. Chem. Soc. 1998, 120, 12988-12989.
31. Roering, A. J.; MacMillan, S. N.; Tanski, J. M.; Water-
man, R., Inorg. Chem. 2007, 46, 6855-6857.
Shu, R.; Hao, L.; Harrod, J. F.; Woo, H.-G.; Samuel, E.,
53.
54.
Gao, D.; Cui, C., Chem. Eur. J. 2013, 19, 11143-11147.
Greb, L.; Tamke, S.; Paradies, J., Chem. Commun. 2014,
32.
354.
33.
8643.
34.
Piers, W. E.; Chivers, T., Chem. Soc. Rev. 1997, 26, 345-
Lawson, J. R.; Melen, R. L., Inorg. Chem. 2017, 56, 8627-
Piers, W. E.; Marwitz, A. J. V.; Mercier, L. G., Inorg.
50, 2318-2320.
55.
Ma, Y.; Wang, B.; Zhang, L.; Hou, Z., J. Am. Chem. Soc.
2016, 138, 3663-3666.
9
56.
Stephan, D. W.; Erker, G., Angew. Chem. Int. Ed. 2015,
54, 6400-6441.
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
Chem. 2011, 50, 12252-12262.
57.
Denis, J.-M.; Forintos, H.; Szelke, H.; Toupet, L.; Pham,
35.
Kenward, A. L.; Piers, W. E., Angew. Chem. Int. Ed.
T.-N.; Madec, P.-J.; Gaumont, A.-C., Chem. Commun. 2003, 39,
54-55.
58.
1026-1028.
59.
Chem. Int. Ed. 1995, 34, 809-811.
60.
114, 3060-3066.
61.
2008, 47, 38-41.
36.
Blackwell, J. M.; Foster, K. L.; Beck, V. H.; Piers, W. E.,
Geier, S. J.; Stephan, D. W., Chem. Commun. 2010, 46,
J. Org. Chem. 1999, 64, 4887-4892.
37.
Parks, D. J.; Blackwell, J. M.; Piers, W. E., J. Org. Chem.
Parks, D. J.; von H. Spence, R. E.; Piers, W. E., Angew.
2000, 65, 3090-3098.
38.
Parks, D. J.; Piers, W. E., J. Am. Chem. Soc. 1996, 118,
Mayr, H.; Basso, N.; Hagen, G., J. Am. Chem. Soc. 1992,
9440-9441.
39.
Houghton, A. Y.; Hurmalainen, J.; Mansikkamäki, A.;
Dobrovetsky, R.; Takeuchi, K.; Stephan, D. W., Chem.
Piers, W. E.; Tuononen, H. M., Nat. Chem. 2014, 6, 983-988.
Commun. 2015, 51, 2396-2398.
62.
40.
Blackwell, J. M.; Sonmor, E. R.; Scoccitti, T.; Piers, W.
The stoichmetric amount of B(C6F5)3 (5 equivalent) re-
E., Org. Lett. 2000, 2, 3921-3923.
action with P-P bonds was reported by Stephan more detail
please see: Geier, S. J.; Stephan, D. W., Chem. Commun. 2010,
46, 1026-1028.
63.
chioni, A., J. Am. Chem. Soc. 2014, 136, 112-115.
64. Rokob, T. A.; Hamza, A.; Stirling, A.; Pápai, I., J. Am.
Chem. Soc. 2009, 131, 2029-2036.
41.
Blackwell, J. M.; Morrison, D. J.; Piers, W. E., Tetrahe-
dron 2002, 58, 8247-8254.
42.
Oestreich, M.; Hermeke, J.; Mohr, J., Chem. Soc. Rev.
Rocchigiani, L.; Ciancaleoni, G.; Zuccaccia, C.; Mac-
2015, 44, 2202-2220.
43.
Chatterjee, I.; Porwal, D.; Oestreich, M., Angew. Chem.
Int. Ed. 2017, 56, 3389-3391.
44.
Hog, D. T.; Oestreich, M., Eur. J. Org. Chem. 2009,
65.
66.
Stephan, D. W., Org. Biomol. Chem. 2008, 6, 1535-1539.
Fasano, V.; Radcliffe, J. E.; Ingleson, M. J., ACS Catal.
2009, 5047-5056.
45.
Rendler, S.; Oestreich, M., Angew. Chem. Int. Ed. 2008,
2016, 6, 1793-1798.
67.
W., Chem, 2017, 3, 259-267.
68.
W., Inorg. Chem. 2008, 47, 1904-1906.
69.
W., Proc. Natl. Acad. Sci. 2014, 111, 10917-10921.
70.
47, 5997-6000.
Liu, L.; Cao, L. L.; Shao, Y.; Ménard, G.; Stephan, D.
46.
Gandhamsetty, N.; Park, S.; Chang, S., J. Am. Chem.
Soc. 2015, 137, 15176-15184.
Welch, G. C.; Holtrichter-Roessmann, T.; Stephan, D.
47.
Gandhamsetty, N.; Park, J.; Jeong, J.; Park, S.-W.; Park,
S.; Chang, S., Angew. Chem. Int. Ed. 2015, 54, 6832-6836.
Pérez, M.; Caputo, C. B.; Dobrovetsky, R.; Stephan, D.
48.
Gandhamsetty, N.; Jeong, J.; Park, J.; Park, S.; Chang,
S., J. Org. Chem. 2015, 80, 7281-7287.
Yin, Q.; Klare, H. F.; Oestreich, M., Angew. Chem. Int.
49.
Hermeke, J.; Mewald, M.; Oestreich, M., J. Am. Chem.
Ed. 2017, 56, 3712-3717.
Soc. 2013, 135, 17537-17546.
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