Synthesis of norbornene-based phosphine-stabilized silylium ions behaving as masked frustrated Lewis pairs

Article abstract of DOI:10.1021/acs.organomet.0c00489

A novel architecture of phosphine-stabilized silylium ions is described. The peculiar moderate flexible framework allows an efficient donation of the phosphine group toward the electron-deficient silicon center, thus providing a very good stabilization of

Full text of DOI:10.1021/acs.organomet.0c00489

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Synthesis of Norbornene-Based Phosphine-Stabilized Silylium Ions
Behaving as Masked Frustrated Lewis Pairs
Aymeric Dajnak, Eddy Maerten,* Nathalie Saffon-Merceron, Antoine Baceiredo, and Tsuyoshi Kato*
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ABSTRACT: A novel architecture of phosphine-stabilized silylium
ions is described. The peculiar moderate flexible framework allows
an efficient donation of the phosphine group toward the electron-
deficient silicon center, thus providing a very good stabilization of
the corresponding silylium ions. The P−Si interaction was studied
in solution and in the solid state by NMR spectroscopy and X-ray
diffraction analysis, respectively. The reactivity of silylium ions is
easily improved using less donating phosphine ligands. Of particular interest, thanks to the flexible ligand framework, the phosphine-
stabilized silylium ion 5f behaves as a frustrated Lewis pair instead of a simple Lewis acid and exhibits an original ambiphilic
reactivity with carbonyl derivatives that allows the synthesis of seven- to nine-membered-ring heterocycles.
The applications of these species have generated great deal
ith the synthesis of the first free silylium ion I, the Reed
Wand Lambert groups have achieved a major synthetic of interest in recent years, especially in the field of catalysis. For
challenge.1 Indeed, because of their exceptionally high Lewis
instance, hydrodefluorination (HDF) reactions of alkyl
fluorides were found to be efficiently catalyzed by intra-
molecularly stabilized silyl cations III−V.5 These species are
also capable of catalyzing Diels−Alder reactions, and the
ferrocene-stabilized system VI developed by the Oestreich
group is particularly efficient for low-temperature cycloaddition
reactions with α,β-unsaturated ketones.6 Interestingly, triar-
ylsilylium ions such as I have been used for the rational design
of new frustrated Lewis pair (FLP) systems able to activate
dihydrogen and to sequester carbon dioxide.7
One of our main objectives is the stabilization of electron-
deficient species,8 and recently, a framework based on
norbornene was designed to stabilize silylenes using
phosphines as Lewis bases.9 Of special interest, we have
shown that, due to the weak coordination of the phosphine
ligand, phosphine-stabilized silylenes remain highly reactive.
Moreover, they present, to some extent, “transition-metal-like
behavior”, as demonstrated by the reversible binding of
ethylene to the Si(II) center10 and the reversible oxidation
addition/reductive elimination of R3SiH at the Si(II) center.11
The key features of this system are the moderate structural
flexibility and the rigid planar structure of the enamino
phosphine fragment, which results in a particular P→Si
interaction. We have thus considered the synthesis of the
acidity, silylium ions have remained elusive species for a long
time.2 To take advantage of these unique species in synthesis
or catalysis, their reactivity needs to be tamed.3 The study of
these species has been facilitated by the use of a Lewis base
that can intramolecularly interact with the silylium center, to
afford a good balance between reactivity and stability (II,
Figure 1).4 Following this strategy, several different types of
donor groups have been introduced to achieve this intra-
molecular stabilization (III−VI, Figure 1).
Received: July 21, 2020
Figure 1. The first free silylium ion and intramolecularly stabilized
silylium ions.
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novel phosphine-stabilized silylium ions 4, which despite a
strong P−Si interaction behave as frustrated Lewis pairs and
allows the synthesis of seven- to nine-membered heterocycles.
A straightforward synthesis of the silylium precursors, the
silylated amino(phosphino) derivatives 2, has been developed
from the corresponding iminophosphines 1 (Scheme 1).9
Scheme 1. Synthesis of Silylium Precursors 2
Figure 2. Molecular structure of 3. Thermal ellipsoids represent 30%
probability. H atoms (except on Si1 and C32), solvent molecules, and
the counterion [B(C6F5)4]− are omitted for clarity. Selected bond
lengths (Å): P1−C1 1.777(2), C1−C2 1.380(3), C2−N1 1.391(3),
N1−C18 1.463(3), P1−C32 1.841(2), C32−C33 1.493(3), C33−
C34 1.337(4), C34−C35 1.463(3), C35−C36 1.460(4), C36−C37
1.339(4), C37−C32 1.508(3), C35−C38 1.372(3), C38−C39
1.486(4), C38−C45 1.484(3).
Attempts to generate silylium ions via the classical Bartlett−
Schneider−Condon method2 using trityl tetrakis-
(pentafluorophenyl)borate have failed. Rather than the hydride
abstraction, the phosphonium salt 3 was obtained nearly
quantitatively, by the reaction of the trityl cation at the 4-
position of a phenyl group (Scheme 2). The same type of
reaction between bulky phosphines (PtBu3 and PCy3) and
trityl salts was already observed by Stephan et al.12
Scheme 3. Preparation of Silylium ions 4b−e and 5f,g
Scheme 2. Reaction of 2a with Trityl Cation
Table 1. NMR Data of Silylium Ions 4b−e (in CD2Cl2 at
Phosphonium salt 3 was fully characterized by NMR
spectroscopy, and its structure was confirmed by X-ray
diffraction analysis (Figure 2.) The P1−C32 bond length is
characteristic of a single bond, and the cyclohexadiene ring
shows alternate single- and double-bond lengths, planar
environments around C35 and C38 (∑ = 359.9 and 360.0°,
respectively), and a tetrahedral environment at C32.
The expected silylium ions 4 can be easily obtained
following the methodology of Kira and Sakurai,13 starting
from the corresponding chlorosilanes 2b−e, just by halide
abstraction using potassium borate salt (Scheme 3).
In order to study the phosphorus−silicon interaction, several
silylium ions were prepared (4b−e) and characterized in
solution and in the solid state. The main spectroscopic data are
summarized in Table 1.
Silylium ions 4c,d with two different substituents on the Si
atom (4c, R2 = Cl, R3 = Me; 4d, R2 = Cl, R3 = H) were
expected to be formed as diastereomer couples since the
298 K)
compd
R2
R3
31P (ppm)
29Si (ppm)
JPSi (Hz)
132.0
172.6, 171.2
169.5
4b
Me
Cl
Cl
Cl
b
Me
Me
H
39.6
30.2, 30.0
28.4
6.1
a
4c
−0.3, −2.1
−22.9
−21.6
b
4d
4e
Cl
21.8
237.4
a
dr = 50:50. Only one diastereomer is formed.
silylium center is stereogenic. A 50:50 diastereomeric ratio was
obtained for 4c, but in the case of 4d, a single diastereomer
was formed. With regard to the strong phosphine−silylium ion
interaction (vide infra), the epimerization of 4 at the chiral
silicon center through P−Si bond dissociation is difficult to
consider. Instead, the diastereoselective formation of 4d is
probably due to a selective Cl abstraction from 2d featuring a
pentacoordinate Si center bearing two different Cl atoms
B
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(apical and equatorial positions). Indeed, the pentacoordinate
nature of the Si atom in 2d with a strong P→Si interaction was
clearly indicated by the significantly high field shifted signals in
29Si and 31P NMR (29Si, −87.2 ppm; 31P, 43.1 ppm) with a
large JSi−P coupling constant (223.8 Hz) in comparison to
those observed for 2c showing typical silane and phosphine
signals (29Si, −5.5 ppm; 31P, 111.3 ppm) in agreement with a
tetracoordinate Si atom without a P→Si interaction (Scheme
4). Note that 2d exists as a single diastereomer presenting a
Scheme 4. 29Si and 31P NMR Chemical Shifts of 2c,d and
the Diastereoselective Formation of 4d
pentacoordinate Si center with a strongly electron withdrawing
Cl atom at the apical position and another Cl atom at the less-
hindered equatorial position. The formation of 4d should take
place exclusively, keeping the configuration at the Si center, via
the cleavage of the more strongly polarized apical Si−Cl bond
in 2d, which explains the high diastereoselectivity of the
reaction. In contrast, in the case of 2c, due to the free rotation
at the N−Si bond axis because of the absence of a P→Si
interaction, the abstraction of the Cl anion is not selective and
thus affords 4c as a mixture of two diastereomers.
An analysis of these spectroscopic data indicates that
silylium 4e, which bears two strongly electron withdrawing
chloride atoms, shows the strongest P−Si interaction, as
indicated by a relatively shielded 31P NMR chemical shift (δ
21.8 ppm) and a large silicon−phosphorus coupling constant
(JPSi = 237.4 Hz). The 29Si NMR chemical shift is also a good
probe to evaluate the Lewis acidity of silylium ions.14 In this
series, 4b exhibits an enhanced Lewis acidity, as indicated by
the 29Si NMR chemical shift, which appears at δ 6.1 ppm,
among the more deshielded signals and the smallest silicon−
phosphorus coupling constant (JPSi = 132.0 Hz). The four
silylium ions 4b−e synthesized were also characterized, in the
solid state, by X-ray diffraction analysis (Figure 3 and Table 2).
The X-ray diffraction data are in good agreement with the
spectroscopic data. Indeed, the longest Si1−P1 bond length
(2.322(1) Å) of the series was found in 4b, suggesting a weak
Si−P interaction: in other words, the strongest Lewis acid of
the series. It is worth noting that the modification of the
silylium center substituent (R2 and R3) has a rather weak effect
on the Si−P interaction.
Figure 3. Molecular structures of 4b−e. Thermal ellipsoids represent
30% probability. Counterions, solvent molecules, disordered atoms,
and hydrogen atoms are omitted for clarity (except the hydrogen
atom on the silicon atom of 4d).
NMR signals at δ 27.2 ppm for 5f and δ 15.4 and 15.3 ppm for
5g in comparison to those observed for the corresponding
silylium ions 4b,c stabilized by a more strongly electron
donating diaminophosphino ligand (4b, δ 6.1 ppm; 4c, δ −0.3
and −2.1 ppm). Again, the smallest JPSi coupling constant is
observed for silylium 5f (R2 = R3 = Me).
Although, the ability of these two families of silylium ions as
catalysts of Diels−Alder reactions between cyclohexadiene or
2,3-dimethylbutadiene and methyl acrylate (10 mol % of
silylium 4 or 5 in CDCl3)4a,6,15 was tested, no trace of the
expected cycloadducts could be detected by NMR spectros-
copy, after several hours at 80 °C. Interestingly, in the case of
5f, the 31P NMR analysis shows the complete disappearance of
the silylium signal (−20.8 ppm) and a new single signal
appearing at δ 20.9 ppm. In fact, silylium ion 5f reacts with 1
equiv of methyl acrylate at 50 °C, leading to an insertion
reaction of the conjugated carbonyl into the P→Si dative bond.
Silylium cation 5f, acting as a frustrated Lewis pair (FLP),7b,16
quantitatively affords the original nine-membered heterocycle
6, which loses the Lewis acid character (silane structure),
probably explaining the absence of any catalytic activity
(Scheme 5).
In order to reduce the Si−P interaction, we have considered
the use of a less electron donating phosphine fragment.
Therefore, the cyclic diaminophosphino group was replaced by
a diphenylphosphino moiety, and the corresponding silylium
ions 5f,g (PR2 = PPh2) have been prepared using the same
synthetic methodology as for 4 (Scheme 3).
The new silylium ions 5 were obtained in nearly quantitative
yields, in the case of 5g (R2 = Cl, R3 = Me) as a mixture of two
diastereomers in a 76:24 ratio. The spectroscopic data are
summarized in Table 3. As expected, the weaker donation of
the diphenylphosphino group is evidenced by deshielded 29Si
The 13C NMR spectrum is particularly informative with the
peculiar chemical shift of the ketene acetal type part CHC of
6, with chemical shift at δ 67.8 ppm (JCP = 10.6 Hz) for the
primary and at δ 156.9 ppm (JCP = 5.5 Hz) for the quaternary
carbon atoms, respectively. In the same vein, we observed at
room temperature the immediate and quantitative insertion of
benzaldehyde into the Si−P bond of silylium 5f.17 The
corresponding seven-membered-ring species 7 was isolated as a
mixture of two diastereomers in a 68:32 ratio and fully
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Table 2. Main Bond Lengths (in Å) Obtained from X-ray Diffraction Analysis of 4b−e
a
b
compd
P1−C1
C1−C2
C2−N1
N1−Si1
Si1−P1
Si1−R2
Si1−R3
4b
4c
4d
4e
1.730(3)
1.708(12)
1.737(9)
1.711(4)
1.369(4)
1.383(16)
1.370(10)
1.368(5)
b
1.371(4)
1.423(16)
1.355(6)
1.368(4)
1.781(3)
1.731(11)
1.734(4)
1.730(3)
2.322(1)
2.302(7)
2.287(2)
2.293(1)
1.844(4)
1.952(13)
2.067(2)
2.014(1)
1.844(4)
1.73(3)
1.44(8)
2.011(1)
a
Si1−R2: Si−CH3 (4b); Si−Cl (4c−e). Si1−R3: Si−CH3 (4b,c); Si−H (4d); Si−Cl (4e).
wider interior angles of the P1−C1−C2−N1−Si1 fragment
(P1−C1−C2 132.36°, C1−C2−N1 130.78°, and C2−N1−Si1
122.63°) in 7, in comparison with those of the phosphine-
silylium ion complex 4b (P1−C1−C2 116.82°, C1−C2−N1
125.50°, and C2−N1−Si1 113.84°). However, 5f is not
reactive enough to activate H2, as observed for the previously
reported frustrated Lewis pairs constituted of free silylium ion
and a bulky phosphine. It should be noted that, in contrast to
our system, the phosphine-stabilized silylium ion with a
naphthalene-based rigid ligand framework (type V in Figure 1)
is very stable and no reactivity of such species has been
described to date.18 Similar FLP-type reactions were also
observed for phosphine-stabilized germylene and stannylenes
with a strained three-membered cyclic structure.19
Table 3. Experimental NMR Parameters of Silylium Ions
5f,g (in CD2Cl2 at 298 K)
compd
R2
R3
31P (ppm)
29Si (ppm)
JPSi (Hz)
82.1
124.6, 117.4
5f
Me
Cl
Me
Me
−20.8
−24.3, −24.1
27.2
15.4, 15.3
a
5g
a
dr = 76:24.
Scheme 5. Reaction of Silylium Ion 5f with Carbonyl
Derivatives
The reactions leading to the formation of cyclic
phosphonium borates 6 and 7 are not reversible. Indeed, no
evolution occurs after prolonged heating of the reaction
mixtures. These adducts are so stable that silylium 5f could not
be regenerated when additional reactants such as phenylsilane
were added.
In conclusion, a new type of phosphine-stabilized silylium
ion, based on a norbornene scaffold, has been described. As
expected, the moderate structural flexibility favors the enamino
phosphine donation to the electrophilic silicon center,
affording stable silylium ions. Phosphine−silicon interactions
were studied both in solution and in the solid state. The
reactivity of silylium ions is easily improved using a more
weakly donating phosphine ligand. Of particular interest,
thanks to the flexible ligand framework, and despite an efficient
intramolecular stabilization, the base-stabilized silylium ion 5f
behaves as a frustrated Lewis pair and allows the synthesis of
seven- to nine-membered heterocycles. Further structural
modifications are actually being performed to improve the
potential of this new class of silylium ions.
EXPERIMENTAL SECTION
■
General Procedures. All manipulations were performed under an
inert atmosphere of argon by using standard Schlenk techniques or
high-pressure NMR tube techniques. Dry and oxygen-free solvents
were used. 1H, 11B, 13C, 19F, 28Si, and 31P NMR spectra were recorded
on Bruker Avance II 300 MHz, Avance III HD 400 MHz, and Avance
Figure 4. Molecular structure of 7. Thermal ellipsoids represent 30%
probability. The counterion, disordered atoms, and hydrogen atoms
are omitted for clarity (except H34). Selected bond lengths (Å) and
angles (deg): P1−C1 1.746(2), C1−C2 1.363(3), C2−N1 1.386(2),
N1−Si1 1.763(2), Si1−C32 1.841(3), Si1−C33 1.844(2), Si1−O1
1.650(2), C34−O1 1.393(2), P1−C34 1.864(2), C34−C35 1.509(3);
P1−C1−C2 132.36(15), C1−C2−N1 130.78(17), C2−N1−Si1
122.63(13), N1−Si1−O1 108.17(7), Si1−O1−C34 129.51(13),
O1−C34−P1 103.54(13), C34−P1−C1 109.32(9).
1
I and II 500 MHz spectrometers. H, 29Si, and 13C NMR chemical
shifts are reported in parts per million (ppm) relative to Me4Si as an
internal standard. 11B NMR downfield chemical shifts are expressed in
ppm relative to BF3·Et2O. 19F chemical shifts are reported in ppm
relative to CFCl3 as an external standard. 31P NMR chemical shifts are
expressed in ppm relative to 85% H3PO4. The following abbreviations
and their combinations are used: br, broad; s, singlet; d, doublet; t,
1
triplet; q, quartet; m, multiplet. H and 13C resonance signals were
characterized by NMR spectroscopy; the structure was
confirmed by X-ray diffraction analysis (Figure 4). The high
reactivity of 5f as a masked FLP can be explained by the weak
P→Si interaction as well as the moderate flexibility of the
ligand framework. Indeed, such a flexibility of the ligand was
clearly confirmed by the significantly elongated P1−Si1
distance (3.624 Å in 7 vs 2.322 Å in 4b) and the associated
attributed by means of 2D COSY, HSQC, and HMBC experiments.
Mass spectra were recorded on a Hewlett-Packard 5989A
spectrometer. All commercially available reagents were used without
further purification unless noted otherwise.
Synthesis of 1. PR2 = P(NtBu)2SiMe2. To a stirred solution of
imine20 (10.0 g, 37.1 mmol) in 80 mL of THF at −78 °C was added
n-butyllithium (1.6 M, 24.3 mL, 38.9 mmol), and the mixture was
D
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warmed to room temperature over 1 h with stirring. The solution was
cooled to −78 °C, and chlorophosphine (9.9 g, 37.1 mmol) was
added. The mixture was warmed to room temperature, and the
solvent was removed under vacuum. The solid was washed with
acetonitrile (3 × 20 mL), dried, and dissolved in pentane, and this
solution was then filtered. The volatile substances were removed
under vacuum, and compound 1 (17.4 g, 94%) was obtained as a
white solid. Spectroscopic data of 1 are in perfect agreement with the
values already reported.20
PR2 = PPh2. To a solution of imine (10.00 g, 37.1 mmol) in THF
(80 mL) was added dropwise at −80 °C a solution of n-butyllithium
(1.6 M) in hexane (23.2 mL, 37.1 mmol), and the mixture was stirred
for 1 h. The reaction mixture was warmed to room temperature and
stirred for 1 h and then cooled again to −80 °C, and
chlorodiphenylphosphine (6.84 mL, 37.1 mmol) was added dropwise.
The resulting solution was warmed to room temperature and stirred
for 1 h, and then the solvent was removed under vacuum. Product 1
was extracted with pentane. After evaporation of the solvent, the solid
was washed with a minimum of acetonitrile to give 1 as a white
powder (11.08 g, 66% yield). Spectroscopic data of 1 are in perfect
agreement with the values already reported.21
0.51 (s, 3H, Si−CH3), 0.47 (s, 3H, Si−CH3). 13C NMR (101 MHz,
2
CDCl3, 328 K): δ 161.4 (d, JCP = 26.0 Hz, N−C), 148.4 (s, Cdipp),
147.4 (s, Cdipp), 142.1 (s, N−Cdipp), 127.5 (s, CHdipp), 124.4 (s,
1
CHdipp), 124.2 (s, CHdipp), 121.2 (d, JCP = 58.5 Hz, C-P), 50.9 (d,
2JCP = 13.6 Hz, CtBu), 50.7 (d, 2JCP = 11.5 Hz, CtBu), 48.6 (d, 2JCP = 3.2
3
Hz, CHbridgehead), 46.7 (s, CH2), 42.8 (s, CHbridgehead), 32.6 (d, JCP
=
3
4.6 Hz, CH3tBu), 32.2 (d, JCP = 5.3 Hz, CH3tBu), 28.2 (s, CH2), 27.9
(s, CHiPr), 27.7 (s, CHiPr), 26.8 (s, CH2), 25.5 (s, CH3iPr), 25.2 (s,
3
CH3iPr), 24.9 (s, CH3iPr), 24.9 (s, CH3iPr), 8.0 (d, JCP = 5.3 Hz, Si−
CH3), 6.3 (s, Si−CH3), 6.1 (br d, JCP = 22.0 Hz, 2 SiCl−CH3). 31P
2
NMR (162 MHz, CDCl3, 328 K): δ 114.0 (br). 29Si NMR (80 MHz,
CDCl3, 328 K): δ 10.3 (br, SiMe2Cl), 9.1 (s, SiMe2).
Synthesis of 2c (R1 = R2 = Cl; R3 = Me). To a solution of
iminophosphine 1 (PR2 = cyclic diaminophosphine) (2.00 g, 4.0
mmol) in THF (20 mL) was added dropwise at −80 °C a 1.6 M
solution of n-butyllithium in hexane (2.5 mL, 4.0 mmol), and the
mixture was stirred for 1 h. The crude mixture was warmed to room
temperature and stirred for 1 h and then cooled to −80 °C, and
trichloromethylsilane (0.47 mL, 4.0 mmol) was added dropwise. The
resulting solution was warmed to room temperature and stirred for 1
h, and then the solvent was removed under vacuum. Product 2c was
extracted with heptane, and colorless crystals were obtained from a
Synthesis of 2a (R1 = H; R2 = R3 = Me). To a solution of
iminophosphine 1 (2.00 g, 4.0 mmol) in THF (25 mL) was added
dropwise at −80 °C a 1.6 M solution of n-butyllithium in hexane (2.5
mL, 4.0 mmol), and the mixture was stirred for 1 h. The reaction
mixture was warmed to room temperature and stirred for 1 h and then
cooled again to −80 °C, and chlorodimethylsilane (0.44 mL, 4.0
mmol) was added dropwise. The resulting solution was warmed to
room temperature and stirred for 1 h, and then the solvent was
removed under vacuum. Product 2a was extracted with heptane from
the crude mixture, and pale yellow crystals were obtained from a
1
saturated heptane solution at −30 °C (1.76 g, 72% yield). H NMR
(500 MHz, CD2Cl2): δ 7.33−7.27 (m, 1H, CHdipp), 7.20−7.14 (m,
2H, CHdipp), 3.73 (s, 1H, CHbridgehead), 3.31 (sept, 3JHH = 6.7 Hz, 1H,
3
CHiPr), 3.18 (sept, JHH = 6.8 Hz, 1H, CHiPr), 2.43 (s, 1H,
CHbridgehead), 1.80−1.63 (m, 2H, CH2), 1.47−1.31 (m, 3H, CH2),
1.28 (d, 3JHH = 6.8 Hz, 3H, CH3iPr), 1.26 (s, 9H, CH3tBu), 1.25−1.18
(m, 3 × 3H, CH3iPr overlapped by CH3tBu), 1.23 (s, 9H, CH3tBu), 1.07
(br s, 3H, SiCl2−CH3), 1.03−1.00 (m, 1H, CH2), 0.48 (s, 3H, Si−
CH3), 0.44 (s, 3H, Si−CH3). 13C NMR (126 MHz, CD2Cl2): δ 159.6
1
2
saturated heptane solution at −30 °C (1.20 g, 54% yield). H NMR
(d, JCP = 25.8 Hz, N−C), 148.9 (s, Cdipp), 147.7 (s, Cdipp), 140.9 (s,
(300 MHz, C6D6): δ 7.15−7.01 (m, 3H, CHdipp), 5.55 (dsept, 2JPH
=
N−Cdipp), 128.3 (s, CHdipp), 124.7 (s, CHdipp), 124.6 (s, CHdipp),
3
123.8 (d, 1JCP = 56.5 Hz, C-P), 51.1 (d, 2JCP = 13.4 Hz, CtBu), 50.9 (d,
15.3 Hz, JH−H = 2.7 Hz, 1H, SiH), 3.86 (s, 1H, CHbridgehead), 3.43
3
3
2
2JCP = 11.6 Hz, CtBu), 48.6 (d, JCP = 2.9 Hz, CHbridgehead), 47.1 (s,
(sept, JHH = 6.9 Hz, 1H, CHiPr), 3.32 (sept, JHH = 6.8 Hz, 1H,
CHiPr), 2.56 (s, 1H, CHbridgehead), 1.98−1.71 (m, 2H, CH2), 1.58−
1.47 (m, 1H, CH2), 1.47−1.38 (m, 2H, CH2), 1.34 (s, 9H, CH3tBu),
1.32 (s, 9H, CH3tBu), 1.28−1.16 (m, 12H, CH3iPr), 1.10−1.03 (m, 2H,
CH2), 0.56 (dd, 3JHH = 2.8 Hz, 3JPH = 4.4 Hz, 3H, SiH−CH3), 0.50 (s,
6H, Si−CH3), 0.14 (dd, 3JHH = 3.2 Hz, 3JPH = 1.9 Hz, 3H, SiH−CH3).
13C NMR (75 MHz, C6D6): δ 163.9 (d, 2JCP = 26.5 Hz, N−C), 147.9
(s, Cdipp), 147.0 (s, Cdipp), 142.3 (s, N−Cdipp), 127.4 (s, CHdipp), 124.4
(s, CHdipp), 124.2 (s, CHdipp), 120.1 (d, 1JCP = 56.5 Hz, C-P), 50.9 (d,
3
CH2), 43.1 (s, CHbridgehead), 32.6 (d, JCP = 4.5 Hz, CH3tBu), 32.2 (d,
3JCP = 5.1 Hz, CH3tBu), 28.4 (s, 2 CHiPr), 28.2 (s, CH2), 28.1 (s, 2
CHiPr), 26.9 (s, CH2), 25.7 (s, CH3iPr), 25.3 (s, CH3iPr), 24.7 (s,
2
CH3iPr), 24.6 (s, CH3iPr), 9.7 (d, JCP = 24.9 Hz, SiCl−CH3), 7.9 (d,
3JCP = 5.2 Hz, Si−CH3), 6.2 (s, Si−CH3). 31P NMR (202 MHz,
CD2Cl2): δ 111.3 (s). 29Si NMR (99 MHz, CD2Cl2): δ 10.1 (s,
SiMe2), −5.5 (s, SiMeCl2).
Synthesis of 2d (R1 = R2 = Cl; R3 = H; PR2 = Cyclic
Diaminophosphine). Intense yellow solid (1.728 g, 72%).
Spectroscopic data are in perfect agreement with the values already
reported.10a
2JCP = 13.7 Hz, CtBu), 50.7 (d, 2JCP = 11.3 Hz, CtBu), 48.1 (d, 2JCP = 3.5
3
Hz, CHbridgehead), 47.0 (s, CH2), 42.9 (s, CHbridgehead), 32.7 (d, JCP
=
3
4.9 Hz, CH3tBu), 32.5 (d, JCP = 5.2 Hz, CH3tBu), 28.8 (s, CH2), 27.9
(s, 2 CHiPr), 26.8 (s, CH2), 25.3 (s, CH3iPr), 25.1 (s, CH3iPr), 24.8 (s,
CH3iPr), 24.6 (s, CH3iPr), 8.0 (d, JCP = 5.3 Hz, Si−CH3), 6.3 (s, Si−
CH3), 0.3 (d, JCP = 24.5 Hz, SiH−CH3), 0.0 (d, JCP = 12.5 Hz,
SiH−CH3). 31P NMR (121 MHz, C6D6): δ 114.5 (d, 2JPH = 15.3 Hz).
29Si NMR (60 MHz, C6D6): δ 8.1 (s, SiMe2), −9.2 (d, 1JSiP = 15.8 Hz,
SiMe2H). Mp: 209 °C.
Synthesis of 2e (R1 = R2 = R3 = Cl). Orange crystals (8.6 g, 66%).
Spectroscopic data are in perfect agreement with the values already
reported.22
3
2
2
Synthesis of 2f (R1 = Cl; R2 = R3 = Me). To a solution of
iminophosphine 1 (PR2 = PPh2) (1.01 g, 2.2 mmol) in THF (25 mL)
was added dropwise at −80 °C a 1.6 M solution of n-butyllithium in
hexane (1.4 mL, 2.2 mmol), and the mixture was stirred for 1 h. The
reaction mixture was then warmed to room temperature and stirred
for 1 h and then cooled again to −80 °C and dichlorodimethylsilane
(0.27 mL, 2.2 mmol) was added dropwise. The resulting solution was
warmed to room temperature and stirred for 1 h before removal of the
solvent under vacuum. Product 2f was extracted with heptane and
colorless crystals were obtained from a saturated heptane solution at
−30 °C (1.11 g, 88% yield). 1H NMR (300 MHz, CD2Cl2): δ 7.45−
6.97 (m, 13H, P(C6H5)2 + 3 CHdipp), 3.70 (s, 1H, CHbridgehead), 3.36−
3.12 (br, 2H, CHiPr), 3.06 (s, 1H, CHbridgehead), 1.89−1.71 (m, 1H +
1H, CH2), 1.60−1.42 (m, 2H, CH2), 1.35−1.28 (m, 1H, CH2), 1.25
Synthesis of 2b (R1 = Cl; R2 = R3 = Me). To a solution of
iminophosphine 1 (PR2 = cyclic diaminophosphine) (2.00 g, 4.0
mmol) in THF (20 mL) was added dropwise at −80 °C a 1.6 M
solution of n-butyllithium in hexane (2.5 mL, 4.0 mmol), and the
mixture was stirred for 1 h. The reaction mixture was warmed to room
temperature and stirred for 1 h, and then cooled again to −80 °C, and
dichlorodimethylsilane (0.48 mL, 4.0 mmol) was added dropwise.
The resulting solution was warmed to room temperature and stirred
for 1 h, and then the solvent was removed under vacuum. Product 2b
was extracted with heptane, and colorless crystals were obtained from
a saturated heptane solution at −30 °C (1.45 g, 61% yield). 1H NMR
(400 MHz, CDCl3, 328 K): δ 7.31−7.25 (m, 1H, CHdipp), 7.20−7.14
(m, 2H, CHdipp), 3.77 (s, 1H, CHbridgehead), 3.40 (sept, 3JHH = 6.8 Hz,
3
3
(d, JHH = 6.8 Hz, 3H, CH3iPr), 1.15 (d, JHH = 6.8 Hz, 3H, CH3iPr),
3
1.04 (d, JHH = 6.8 Hz, 3H, CH3iPr), 0.82−0.20 (br, 6H + 1H, 2 Si−
3
3
1H, CHiPr), 3.25 (sept, JHH = 6.8 Hz, 1H, CHiPr), 2.51 (s, 1H,
CH3 + CH2), 0.74 (d, JHH = 6.9 Hz, 3H, CH3iPr). 13C NMR (75
2
CHbridgehead), 1.84−1.65 (m, 2H, CH2), 1.52−1.36 (m, 3H, CH2),
1.35−1.26 (m, 6H, CH3iPr), 1.31 (s, 9H, CH3tBu), 1.28 (s, 9H,
CH3tBu), 1.25 (d, 3JHH = 6.8 Hz, 12H, CH3iPr), 1.24 (d, 3JHH = 6.8 Hz,
12H, CH3iPr), 1.06−1.01 (m, 1H, CH2), 0.72 (br, 6H, SiCl−CH3),
MHz, CD2Cl2): δ 165.0 (d, JCP = 21.2 Hz, N−C), 148.8 (s, Cdipp),
148.7 (s, Cdipp), 146.2 (s, Cdipp), 146.2 (s, Cdipp), 143.7 (d, 1JCP = 12.5
Hz, P−CPh), 140.4 (d, 4JCP = 3.6 Hz, N−Cdipp), 138.6 (d, 1JCP = 17.4
Hz, P−CPh), 136.8 (d, JCP = 25.2 Hz, CHPh), 131.6 (d, JCP = 15.1 Hz,
E
https://dx.doi.org/10.1021/acs.organomet.0c00489
Organometallics XXXX, XXX, XXX−XXX

Organometallics
pubs.acs.org/Organometallics
Article
CHPh), 129.1 (s, CHPh), 128.2 (s, CHPh), 127.9 (d, JCP = 2.5 Hz,
CHPh), 127.8 (d, JCP = 3.0 Hz, CHPh), 126.3 (s, CHdipp), 125.4 (s,
31P NMR (162 MHz, CD2Cl2, 213 K): δ 49.3 (s). 19F NMR (376
MHz, CD2Cl2): δ −132.8 (br, CAr−Fortho), −163.5 (t, JFF = 20.4 Hz,
CAr−Fpara), −167.3 (t, JFF = 18.0 Hz, CAr−Fmeta). 11B NMR (128
MHz, CD2Cl2, 213 K): δ −16.9 (s, BAr). 29Si NMR (80 MHz,
CD2Cl2, 213 K): δ 22.3 (d, 2JSiP = 4.5 Hz, SiMe2), −3.7 (s, SiMe2H).
Synthesis of 4b (R2 = R3 = Me). To a solution of 2b (300 mg,
0.50 mmol) in dichloromethane (3 mL) was added potassium
tetrakis(pentafluorophenyl)borane (0.360, 0.50 mmol). After it was
stirred for 10 min, the solution was filtered then the solvents were
removed under vacuum to give 4b as a white powder (0.490 g, 79%).
Crystals suitable for X-ray diffraction analysis were obtained from a
concentrated dichloromethane solution. 1H NMR (300 MHz,
CD2Cl2): δ 7.45−7.24 (m, 3H, CHdipp), 3.39 (s, 1H, CHbridgehead),
2.96 (sept, 3JHH = 6.7 Hz, 1H, CHiPr), 2.83 (sept, 3JHH = 6.7 Hz, 1H,
CHiPr), 2.71 (s, 1H, CHbridgehead), 2.06−1.83 (m, 2H, CH2), 1.81−
1.66 (m, 2H, CH2), 1.61−1.52 (m, 2H, CH2), 1.40 (s, 9H, CH3tBu),
1
CHdipp), 124.6 (s, CHdipp), 107.2 (d, JCP = 21.5 Hz, C−P), 49.1 (d,
3
3JCP = 5.5 Hz, CHbridgehead), 47.2 (s, CH2), 47.0 (d, JCP = 5.2 Hz,
CHbridgehead), 28.5 (s, CHiPr), 28.2 (s, CHiPr), 27.7 (s, CH2), 27.6 (s,
CH2), 25.9 (s, CH3iPr), 25.0 (s, CH3iPr), 24.9 (s, CH3iPr), 24.6 (d, JCP
=
5.8 Hz, CH3iPr), 5.1 (br, Si−CH3). 31P NMR (121 MHz, CD2Cl2): δ
−25.4. 29Si NMR (60 MHz, CD2Cl2): δ 11.5. Mp: 101.1 °C.
Synthesis of 2g (R1 = R2 = Cl; R3 = Me). To a solution of
iminophosphine 1 (PR2 = PPh2) (2.94 g, 6.5 mmol) in THF (25 mL)
was added dropwise at −80 °C a 1.6 M solution of n-butyllithium in
hexane (4.14 mL, 6.5 mmol), and the mixture was stirred for 1 h. The
reaction mixture was warmed to room temperature and stirred for 1 h
and then cooled again to −80 °C, and trichloromethylsilane (0.78
mL, 6.5 mmol) was added dropwise. The resulting solution was
warmed to room temperature and stirred for 1 h before removal of the
solvent under vacuum. Product 2g was extracted with heptane, and
pale yellow crystals were obtained from a saturated heptane solution
at −30 °C (2.48 g, 67% yield). 1H NMR (300 MHz, C6D6): δ 7.43−
6.90 (m, 13H, P(C6H5)2) + 3 CHdipp), 3.91 (s, 1H, CHbridgehead), 3.42
3
1.37 (s, 9H, CH3tBu), 1.29 (d, JHH = 4.0 Hz, 3H, CH3iPr), 1.26 (d,
3JHH = 6.8 Hz, 3H, CH3iPr), 1.18 (d, 3JHH = 4.0 Hz, 3H, CH3iPr), 1.16
(d, 3JHH = 6.7 Hz, 3H, CH3iPr), 0.82 (d, 3JHP = 6.6 Hz, 3H, Si+−CH3),
0.77 (s, 3H, Si−CH3), 0.69 (d, 3JHP = 6.4 Hz, 3H, Si+−CH3), 0.65 (s,
3
3
2
3H, Si−CH3). 13C NMR (75 MHz, CD2Cl2): δ 192.3 (d, JCP= 25.9
(sept, JHH = 6.7 Hz, 1H, CHiPr), 3.28 (sept, JHH = 6.9 Hz, 1H,
CHiPr), 3.08 (s, 1H, CHbridgehead), 1.91−1.76 (m, 1H, CH2), 1.75−
1.50 (m, 2H, CH2), 1.45−1.30 (m, 1H, CH2), 1.24 (d, 3JHH = 6.7 Hz,
3H, CH3iPr), 1.17 (d, 3JHH = 6.7 Hz, 3H, CH3iPr), 1.09 (d, 3JHH = 6.9
Hz, N−C), 148.6 (br d, JCF = 241.3 Hz, CAr−F), 147.5 (s, Cdipp),
147.3 (s, Cdipp), 138.6 (br d, JCF = 244.8 Hz, CAr−F), 136.7 (br d, JCF
3
= 245.8 Hz, CAr−F), 132.1 (d, JCP = 3.1 Hz, N−Cdipp), 129.9 (s,
3
CHdipp), 125.8 (s, CHdipp), 125.7 (s, CHdipp), 99.0 (d, 1JCP = 68.9 Hz,
Hz, 3H, CH3iPr), 0.95−0.80 (m, 1H, CH2), 0.78 (d, JHH = 6.9 Hz,
3H, CH3iPr), 0.44 (s, 3H, Si−CH3). 13C NMR (75 MHz, C6D6): δ
162.7 (d, 2JCP = 20.7 Hz, N−C), 149.2 (d, 5JCP = 6.2 Hz, Cdipp), 146.2
(d, 5JCP = 2.2 Hz, Cdipp), 143.4 (d, 1JCP = 12.4 Hz, P−CPh), 138.9 (d,
4JCP = 3.8 Hz C−N), 138.1 (d, 1JCP = 17.6 Hz, P−CPh), 136.9 (d, JCP
= 25.4 Hz, CHPh), 131.7 (d, JCP = 15.1 Hz, CHPh), 129.3 (s, CHPh),
129.1 (s, CHPh), 128.0 (d, JCP = 6.1 Hz, CHPh) overlapped by
deuterated solvent), 127.9 (d, JCP = 11.9 Hz, CHPh overlapped by
deuterated solvent), 126.5 (s, CHdipp), 125.4 (s, CHdipp), 125.1 (s,
2
2
C−P), 53.3 (d, JCP = 21.2 Hz, CtBu), 53.2 (d, JCP = 19.4 Hz, CtBu),
3
2
48.7 (d, JCP = 6.0 Hz, CH2), 45.0 (d, JCP = 10.5 Hz, CHbridgehead),
41.5 (s, CHbridgehead), 32.9 (d, JCP = 5.6 Hz, CH3tBu), 32.6 (d, JCP
3
3
=
5.6 Hz, CH3tBu), 28.5 (s, CHiPr), 28.4 (s, CHiPr), 28.1 (s, CH2), 26.1
3
(s, CH3iPr), 25.7 (d, JCP = 1.8 Hz, CH2), 25.3 (s, CH3iPr), 24.5 (s,
3
CH3iPr), 24.4 (s, CH3iPr), 6.1 (s, Si−CH3), 4.3 (d, JCP = 1.8 Hz, Si−
CH3), 1.4 (d, 2JCP = 14.2 Hz, Si+−CH3), 0.7 (d, 2JCP = 13.4 Hz, Si+−
CH3). Cipso attached to the boron atom could not be detected. 31P
NMR (121 MHz, CD2Cl2): δ 39.6 (1JPSi = 132 Hz). 11B NMR (96
MHz, CD2Cl2): δ −16.6 (s, BAr). 19F NMR (282 MHz, CD2Cl2): δ
−133.0 (br, CAr−Fortho), −163.7 (t, JFF = 20.3 Hz, CAr-Fpara), −167.5
(t, JFF = 18.3 Hz, CAr-Fmeta). 29Si NMR (60 MHz, CD2Cl2): δ 21.4 (d,
1
3
CHdipp), 111.1 (d, JCP = 24.0 Hz, C-P), 49.2(d, JCP = 4.9 Hz,
CHbridgehead), 47.4 (s, CH2), 47.1(d, JCP = 5.1 Hz, CHbridgehead), 28.7
2
(s, CHiPr), 28.2 (s, CHiPr), 27.5 (s, CH2), 27.4 (s, CH2), 26.0 (d, JCP
=
6.2 Hz, CH3iPr), 25.1 (s, CH3iPr), 24.8 (s, CH3iPr), 24.6 (s, CH3iPr), 6.9
(s, Si−CH3). 31P NMR (121 MHz, C6D6): δ −26.1. 29Si NMR (60
MHz, C6D6): δ −5.0. Mp: 94.3 °C.
1
2JSiP = 2.9 Hz, SiMe2), 6.1 (d, JSiP = 132.0 Hz, Si+). Anal. Calcd for
C55H55BF20N3PSi2: C, 53.45; H, 4.49; N, 3.40. Found: C, 53.21; H,
4.43; N, 3.38. Mp: 86.1 °C.
Synthesis of 3. To a solution of 2a (300 mg, 0.54 mmol) in
dichloromethane (4 mL) was added trityl cation (496 mg, 0.54
mmol), and the reaction mixture turned red immediately. The
solution was concentrated and cooled as quickly as possible to −30
°C, affording 3 as pink crystals (0.437 g, 55% yield). The product is
not stable in solution at room temperature, and therefore we applied
Synthesis of 4c (R2 = Me; R3 = Cl). White powder (0.504 g,
82%). Crystals suitable for X-ray diffraction analysis were obtained
from a concentrated dichloromethane solution. A 50:50 diastereomer
1
mixture was obtained. H NMR (400 MHz, CD2Cl2): δ 7.47−7.40
(m, 2H, CHdipp), 7.35−7.26 (m, 4H, CHdipp), 3.43 (s, 2H,
1
3
3
low-temperature NMR (213 K) to characterize it. H NMR (400
CHbridgehead), 3.07 (sept, JHH = 6.6 Hz, 1H, CHiPr), 2.91 (sept, JHH
3
MHz, CD2Cl2, 213 K): δ 7.44−7.09 (m, 13H, C(C6H5)2 and CHdipp),
= 6.9 Hz, 1H, CHiPr overlapped with CHiPr), 2.89 (sept, JHH = 6.9
6.95 (br, 2H, P−CH−CHCH), 6.13 (br, 2H, P−CH−CHCH),
Hz, 1H, CHiPr overlapped with CHiPr), 2.83−2.70 (br, 1H, CHiPr
overlapped by CHbridgehead), 2.83−2.70 (br, 2H, CHbridgehead over-
lapped by CHiPr), 2.05−1.89 (m, 4H, CH2), 1.81−1.66 (m, 4H, CH2),
1.64−1.56 (m, 2H, CH2), 1.45 (d, 4JPH = 0.88 Hz, 9H, CH3tBu), 1.44
(d, 4JPH = 0.87 Hz, 3H, CH3tBu), 1.40 (d, 4JPH = 0.98 Hz, 3H, CH3tBu),
140−1.36 (m, 2H, CH2), 1.38 (d, 4JPH = 0.94 Hz, 3H, CH3tBu), 1.32−
1.26 (m, 12H, CH3iPr), 1.21−1.14 (m, 12H, CH3iPr overlapped by
Si+−CH3), 1.21−1.14 (d, 3JPH = 4.1 Hz*, 3H, Si+−CH3 overlapped by
CH3iPr), 1.03 (d, 3JPH = 4.1 Hz, 3H, Si+−CH3), 0.81 (d, 2JPH = 2.2 Hz,
2
5.20 (d, JPH = 36.2 Hz, 1H, P−CH), 5.04 (br s, 1H, SiH), 3.79 (br,
1H, CHbridgehead), 3.22 (br, 1H, CHiPr), 3.06 (br, 1H, CHiPr), 2.96 (br,
1H, CHbridgehead), 2.07−1.61 (br(m), 3H, 2 CH2), 1.57−0.97 (m,
15H, 4 CH3iPr and 2 CH2), 1.41 (s, 9H, CH3tBu), 1.34 (s, 9H, CH3tBu),
0.77 (s, 3H, Si−CH3), 0.76 (s, 3H, Si−CH3), 0.46 (s, 3H, SiH−CH3),
−0.10 (s, 3H, SiH−CH3). 13C NMR (101 MHz, CD2Cl2, 213 K): δ
174.0 (d, 2JCP = 7.1 Hz, N−C), 147.8 (br d, JCF = 240.0 Hz, CAr−F),
147.0 (s, Cdipp), 145.8 (s, Cdipp), 143.4 (d, JCP = 12.7 Hz, C(Ph)2),
140.7 (d, JCP = 4.4 Hz, CPh), 140.6 (d, JCP = 4.3 Hz, CPh), 138.7 (s,
2
6H, Si−CH3), 0.70 (d, JPH = 2.5 Hz, 6H, Si−CH3). * coupling
N−Cdipp), 138.2 (br d, JCF = 245.7 Hz, CAr-F), 136.1 (br d, JCF
=
constant determined by HSQC 29Si−1H. 13C NMR (101 MHz,
CD2Cl2): δ 192.4 (d, 2JCP = 23.2 Hz, N−C), 192.3 (d, 2JCP = 23.2 Hz,
N−C), 148.6 (br d, JCF = 240.4 Hz, CAr-F), 148.1 (s, Cdipp), 147.9 (s,
245.1 Hz, CAr-F), 131.9 (d, 3JCP = 16.3 Hz, P-CH−CHCH), 131.7
3
(d, JCP = 14.1 Hz, P−CH−CHCH), 130.8 (s, CHPh and CHdipp),
128.3 (CHPh), 128.2 (CHPh), 125.8 (d, JCP = 12.5 Hz, CC(Ph)2),
125.6 (s, CHdipp), 125.5 (s, CHdipp), 123.7 (br, B−CAr), 120.9 (br, P−
CH−CHCH), 119.4 (br, P−CH−CHCH), 101.9 (d, 1JCP = 89.7
Hz, C−P), 53.5 (d, CtBu overlapped by deuterated solvant), 53.4 (d,
Cdipp), 147.0 (s, Cdipp), 146.7 (s, Cdipp), 138.6 (br d, JCF = 245.1 Hz,
CAr−F), 136.7 (br d, JCF = 246.4 Hz, CAr−F), 130.7 (d, 3JCP = 2.8 Hz,
N−Cdipp), 130.6 (d, 3JCP = 2.6 Hz, N−Cdipp), 130.4 (s, CHdipp), 130.3
(s, CHdipp), 126.3 (s, CHdipp), 126.2 (s, CHdipp), 125.8 (s, CHdipp),
125.7 (s, CHdi1pp), 124.4 (broad s, B−CAr), 99.3 (d, 1JCP = 74.6 Hz, C−
P), 99.2 (d, JCP = 72.8 Hz, C−P), 54.4 (d, CtBu overlapped by
2
CtBu overlapped by deuterated solvant), 51.9 (d, JCP = 11.6 Hz,
CHbridgehead), 49.1 (d, 2JCP = 8.6 Hz, CHbridgehead), 47.3 (d, 2JCP = 61.5
Hz, P−CH), 43.8 (s, CH2), 32.3 (d, 2 CH3tBu overlapped), 28.4 (s,
CHiPr), 28.0 (s, CH2), 27.9 (s, CHiPr), 26.9 (s, CH2), 25.3 (s, CH3iPr),
25.0 (s, CH3iPr), 24.9 (s, CH3iPr), 24.7 (s, CH3iPr), 4.7 (s, Si−CH3), 3.6
2
2
deuterated solvant), 54.2 (d, JCP = 1.5 Hz, CtBu), 53.7 (d, JCP = 1.2
Hz, CtBu), 53.5 (d, 2JCP = 1.2 Hz, CtBu), 48.9 (d, 3JCP = 6.7 Hz, CH2),
48.4 (d, JCP = 6.1 Hz, CH2), 45.3 (s, CHbridgehead), 45.2 (s,
CHbridgehead), 41.8 (s, CHbridgehead), 41.6 (s, CHbridgehead), 32.8 (d, JCP
3
3
3
(d, JCP = 2.9 Hz, Si−CH3), 2.8 (s, SiH−CH3), −3.4 (s, SiH−CH3).
F
https://dx.doi.org/10.1021/acs.organomet.0c00489
Organometallics XXXX, XXX, XXX−XXX

Organometallics
pubs.acs.org/Organometallics
Article
3
3
= 5.6 Hz, 2 CH3tBu), 32.5 (d, JCP = 5.8 Hz, CH3tBu), 32.4 (d, JCP
=
C53H49BCl2F20N3PSi2: C, 49.86; H, 3.87; N, 3.29. Found: C, 49.79;
H, 3.83; N, 3.35. Mp: 189.4 °C.
5.6 Hz, CH3tBu), 28.8 (s, CHiPr), 28.7 (s, CHiPr), 28.6 (s, CHiPr), 28.5
(s, CHiPr), 27.9 (s, CH2), 27.6 (s, CH2), 26.1 (s, CH3iPr), 25.7 (s,
Synthesis of 5f (R2 = R3 = Me). To a solution of 2f (136 mg, 0.25
mmol) in dichloromethane (2 mL) was added potassium tetrakis-
(pentafluorophenyl)borane (179 mg, 0.25 mmol). After it was stirred
for 10 min, the solution was filtered and all the volatiles were removed
under vacuum to give 5f as a white powder (213 mg, 72%). 1H NMR
(300 MHz, CD2Cl2): δ 7.83−7.56 (m, 10H, P(C6H5)2), 7.45−7.20
(m, 3H, CHdipp), 3.55 (s, 1H, CHbridgehead), 3.06 (sept, 3JHH = 6.7 Hz,
3
3
CH3iPr), 25.5 (d, JCP = 1.8 Hz, CH2), 25.5 (d, JCP = 1.8 Hz, CH2),
25.3 (s, CH3iPr), 25.1 (s, CH3iPr), 25.0 (s, CH3iPr), 24.9 (s, CH3iPr),
24.4 (s, CH3iPr), 24.3 (s, CH3iPr), 6.0 (s, Si−CH3), 5.9 (s, 2 Si−CH3),
4.4 (d, 2JCP = 18.9 Hz, Si+−CH3), 4.3 (d, 3JCP = 1.7 Hz, Si−CH3), 4.2
(d, JCP = 1.7 Hz, Si−CH3), 3.7 (d, JCP = 18.0 Hz, Si+−CH3). 31P
3
2
NMR (162 MHz, CD2Cl2): δ 30.2 (1JPSi = 172.6 Hz), 30.0 (1JPSi
=
171.2 Hz). 11B NMR (160 MHz, CD2Cl2): δ −16.6 (s, BAr). 19F
NMR (471 MHz, CD2Cl2): δ −132.5 (br, CAr−Fortho), −163.3 (t, JFF
= 20.5 Hz, CAr−Fpara), −167.0 (t, JFF = 19.3 Hz, CAr−Fmeta). 29Si
NMR (99 MHz, CD2Cl2): δ 23.8 (d, 2JSiP = 2.5 Hz, SiMe2), 23.8 (d,
3
1H, CHiPr), 2.79 (s, 1H, CHbridgehead), 2.66 (sept, JHH = 6.8 Hz, 1H,
CHiPr), 2.10−1.91 (m, 2 + 1H, CH2), 1.67−1.58 (m, 1H, CH2),
3
1.53−1.41 (m, 2H, CH2), 1.28 (d, JHH = 6.7 Hz, 3H, CH3iPr), 1.26
3
3
(d, JHH = 6.7 Hz, 3H, CH3iPr), 1.14 (d, JHH = 6.8 Hz, 3H, CH3iPr),
2JSiP = 2.7 Hz, SiMe2), −0.3 (d, 1JSiP = 172.6 Hz, Si+), −2.1 (d, 1JSiP
171.2 Hz, Si+). Mp: 157.7 °C.
=
3
3
1.06 (d, JHH = 6.8 Hz, 3H, CH3iPr), 0.81 (d, JPH = 6.6 Hz, 3H, Si−
CH3), 0.51 (d, JPH = 6.6 Hz, 3H, Si−CH3). 13C NMR (75 MHz,
3
Synthesis of 4d (R2 = Cl; R3 = H). White powder (0.511 g, 82%).
Crystals suitable for X-ray diffraction analysis were obtained from a
concentrated chloroform solution. A single diastereomer was
obtained. 1H NMR (400 MHz, CDCl3): δ 7.49−7.43 (m, 1H,
CD2Cl2): δ 187.5 (d, 2JCP = 16.4 Hz, N−C), 148.7 (br d, JCF = 241.3
Hz, CAr−F), 148.0 (s, Cdipp), 147.9 (s, Cdipp), 138.8 (br d, JCF = 244.6
Hz, CAr−F), 136.7 (br d, JCF = 247.3 Hz, CAr−F), 134.5 (d, JCP = 3.4
Hz, CHPh), 134.4 (d, JCP = 3.4 Hz, CHPh), 133.2 (d, JCP = 11.2 Hz,
CHPh), 132.4 (d, JCP = 11.3 Hz, CHPh), 131.6 (d, JCP = 2.2 Hz, N−
2
CHdipp), 7.33−7.28 (m, 2H, CHdipp), 5.90 (d, 1H, JPH = 58.4 Hz,
SiH), 3.45 (s,1H, CHbridgehead), 2.96 (sept, 3JHH = 6.9 Hz, 1H, CHiPr),
2.87 (sept, 3JHH = 6.9 Hz, 1H, CHiPr overlapped by CHbridgehead), 2.83
(s, 1H, CHbridgehead overlapped by CHiPr), 2.07−1.93 (m, 2H, CH2),
1.82−1.60 (m, 4H, 2 CH2), 1.43 (d, 9H, 4JPH = 0.8 Hz, CH3tBu), 1.41
C
dipp), 131.0 (d, JCP = 12.5 Hz, CHPh), 130.9 (d, JCP = 12.7 Hz,
CHPh), 130.0 (s, CHdipp), 125.8 (s, CHdipp), 125.7 (s, CHdipp), 121.7
(d, 1JCP = 70.3 Hz, P−CPh), 119.5 (d, 1JCP = 74.0 Hz, P−CPh), 86.7 (d,
1JCP = 73.2 Hz, C-P), 49.3 (d, 3JCP = 5.0 Hz, CH2), 45.1 (d, 2JCP = 8.9
4
3
3
(d, 9H, JPH = 0.8 Hz, CH3tBu), 1.29 (d, 3H, JHH = 6.8 Hz, CH3iPr),
Hz, CHbridgehead), 42.8 (d, JCP = 1.0 Hz, CHbridgehead), 29.1 (s, CH2),
3
3
28.7 (s, CHiPr), 28.6 (s, CHiPr), 26.4 (d, 3JCP = 2.1 Hz, CH2), 25.6 (s,
CH3iPr), 25.4 (s, CH3iPr), 24.9 (s, CH3iPr), 23.6 (s, CH3iPr), −0.33 (d,
1.27 (d, 3H, JHH = 6.8 Hz, CH3iPr), 1.24 (d, 6H, JHH = 6.8 Hz, 2
CH3iPr), 0.80 (s, 3H, SiMe2), 0.72 (s, 3H, SiMe2). 13C NMR (101
2
MHz, CDCl3): δ 192.3 (d, JCP= 22.2 Hz, N−C), 148.2 (br d, JCF
=
=
2
2JCP = 15.0 Hz, Si+−CH3), −3.0 (d, JCP = 11.0 Hz, Si+−CH3). Cipso
241.3 Hz, CAr−F), 146.7 (s, Cdipp), 146.6 (s, Cdipp), 138.3 (br d, JCF
attached to the boron atom could not be detected. 31P NMR (121
MHz, CD2Cl2): δ −20.8 (1JPSi = 82.1 Hz). 19F NMR (282 MHz,
CD2Cl2): δ −132.9 (br, CAr−Fortho), −163.6 (t, JFF = 20.4 Hz, CAr−
244.9 Hz, CAr−F), 136.2 (br d, JCF = 244.1 Hz, CAr−F), 130.4 (s,
CHdipp), 130.1 (s, N−Cdipp), 125.6 (s, 2 CHdipp), 100.3 (d, 1JCP = 76.7
Hz, C−P), 53.5 (br, CtBu), 53.4 (br, CtBu), 48.3 (d, JCP = 6.4 Hz, CH2),
F
para), −167.4 (t, JFF = 18.1 Hz, CAr−Fmeta). 11B NMR (96 MHz,
3
44.8 (d, JCP = 10.0 Hz, CHbridgehead), 41.6 (s, CHbridgehead), 32.6 (d,
CD2Cl2): δ −16.6 (s, BAr). 29Si NMR (60 MHz, CD2Cl2): δ 27.2 (d,
1JPSi = 82.1 Hz). Mp: 84.6 °C.
3JCP = 5.8 Hz, CH3tBu), 32.4 (d, JCP = 5.8 Hz, CH3tBu), 28.8 (s,
3
CHiPr), 28.6 (s, CHiPr), 27.6 (s, CH2), 25.1 (s, CH3iPr), 24.8 (d, JCP
=
Synthesis of 5g (R2 = Cl; R3 = Me). To a solution of 2g (300 mg,
0.53 mmol) in dichloromethane (2 mL) was added potassium
tetrakis(pentafluorophenyl)borane (380 mg, 0.53 mmol). After it was
stirred for 10 min, the solution was filtered by cannula and evaporated
under vacuum to give 5g as a white powder (484 mg, 76%). Data for
the major isomer (76%) are as follows. 1H NMR (500 MHz,
CD2Cl2): δ 7.89−7.60 (m, 10H, P(C6H5)2), 7.48−7.39 (m, 1H,
CHdipp), 7.37−7.29 (m, 1H, CHdipp), 7.24−7.19 (m, 1H, CHdipp),
3.58 (s, 1H, CHbridgehead), 3.28 (sept, 3JHH = 6.8 Hz, 1H, CHiPr), 2.83
(s, 1H, CHbridgehead), 2.46 (sept, 3JHH = 6.7 Hz, 1H, CHiPr), 2.11- 1.91
1.7 Hz, CH2), 24.7 (s, CH3iPr), 24.5 (s, CH3iPr), 24.2 (s, CH3iPr), 5.1
(s, SiMe2), 3.9 (d, 3JCP = 1.7 Hz, SiMe2). Cipso attached to the boron
atom could not be detected. 31P NMR (162 MHz, CDCl3): δ 28.2
(1JSiP = 169.1 Hz, JPH = 58.5 Hz). 11B NMR (160 MHz, CDCl3): δ
2
−16.6 (s, BAr). 19F NMR (471 MHz, CDCl3): δ −132.5 (br, CAr-
F
ortho), −163.3 (t, JFF = 20.5 Hz, CAr-Fpara), −167.0 (t, JFF = 19.3 Hz,
CAr−Fmeta). 29Si NMR (60 MHz, CDCl3): δ 24.0 (s, SiMe2), −23.3 (d,
1JSiP = 169.1 Hz, Si+). Mp: 150.3 °C.
Synthesis of 4e (R2 = R3 = Cl). White powder (0.466 g, 77%).
Crystals suitable for X-ray diffraction analysis were obtained from a
3
(m, 2H, CH2), 1.68−1.34 (m, 4H, 2 CH2), 1.28 (d, JHH = 6.7 Hz,
1
concentrated chloroform solution. H NMR (300 MHz, CD2Cl2): δ
3H, CH3iPr), 1.27 (d, 3JHH = 6.7 Hz, 3H, CH3iPr), 1.08 (d, 3JHH = 6.8
7.54−7.24 (m, 3H, CHdipp), 3.48 (s, 1H, CHbridgehead), 3.01 (sept, 3JHH
3
Hz, 3H, CH3iPr), 0.94 (d, JHH = 6.8 Hz, 3H, CH3iPr), 0.83 (d, 3JPH
=
3
= 6.8 Hz, 1H, CHiPr), 2.93−2.77 (sept, JHH = 6.7 Hz, 1H, CHiPr
4.3 Hz, 3H, Si−CH3). 13C NMR (126 MHz, CD2Cl2): δ 185.9 (d,
overlapped by CHbridgehead), 2.88−2.77 (s,1H, CHbridgehead overlapped
by CHiPr), 2.12- 1.55 (m, 2H, CH2), 2.12- 1.55 (m, 2H, CH2), 2.12-
1.55 (m, 2H, CH2), 1.46 (s, 9H, CH3tBu), 1.45 (s, 9H, CH3tBu),1.33
2JCP = 13.1 Hz, N−C), 148.6 (br d, JCF = 241.7 Hz, CAr−F), 148.4 (s,
C
dipp), 147.5 (s, Cdipp), 138.7 (br d, JCF = 243.8 Hz, CAr−F), 136.7 (br
d, JCF = 243.8 Hz, CAr−F), 135.4 (d, JCP = 3.4 Hz, CHPh), 135.2 (d,
CP = 3.5 Hz, CHPh), 134.0 (d, JCP = 11.1 Hz, CHPh), 132.6 (d, JCP
3
3
(d, 3H, JHH = 5.5 Hz, CH3iPr), 1.31 (d, 3H, JHH = 5.5 Hz, CH3iPr),
0.80 (d, 6H, 3JHH = 6.7 Hz, CH3iPr), 0.85 (s, 3H, SiMe2), 0.75 (s, 3H,
J
=
SiMe2). 13C NMR (75 MHz, CD2Cl2): δ 191.7 (d, JCP = 20.2 Hz,
2
11.4 Hz, CHPh), 131.5 (d, JCP = 12.8 Hz, CHPh), 130.9 (d, JCP = 13.3
Hz, CHPh), 130.5 (s, CHdipp), 126.2 (s, CHdipp), 125.6 (s, CHdipp),
N−C), 148.0 (br d, JCF = 243.6 Hz, CAr−F), 147.2 (s, Cdipp), 146.9 (s,
124.5 (br, B−CAr), 119.5 (d, 1JCP = 72.5 Hz, P−CPh), 116.4 (d, 1JCP
=
C
dipp), 138.3 (br d, JCF = 245.5 Hz, CAr−F), 136.3 (br d, JCF = 247.4
1
3
77.5 Hz, P−CPh), 89.2 (d, JCP = 74.6 Hz, C−P), 49.1 (d, JCP = 5.5
Hz, CAr−F), 130.3 (s, CHdipp), 129.0 (br, N−Cdipp), 125.8 (s, CHdipp),
Hz, CH2), 45.4 (d, 2JCP = 8.5 Hz, CHbridgehead), 43.1 (d, 3JCP = 1.8 Hz,
1
3
125.7 (s, CHdipp), 98.6 (d, JCP = 80.1 Hz, C−P), 54.3 (d, JCP = 1.9
3
CHbridgehead), 29.0 (s, 2 CHiPr), 28.8 (s, CH2), 26.1 (d, JC = 2.3 Hz,
Hz, CtBu), 54.1 (d, CtBu overlapped by deuterated solvent), 47.9 (d, JCP
2
3
CH2), 25.5 (s, CH3iPr), 25.5 (s, CH3iPr), 24.8 (s, CH3iPr), 23.1 (s,
CH3iPr), 0.0 (d, 2JCP = 15.1 Hz, Si+−CH3). Cipso attached to the boron
atom could not be detected. 31P NMR (202 MHz, CD2Cl2): δ −24.3
(1JPSi = 124.6 Hz). 19F NMR (471 MHz, CD2Cl2): δ −133.0 (br,
CAr−Fortho), −163.6 (t, JFF = 20.4 Hz, CAr−Fpara), −167.4 (t, JFF = 18.1
Hz, CAr−Fmeta). 11B NMR (160 MHz, CD2Cl2): δ −16.6 (s, BAr). 29Si
NMR (99 MHz, CD2Cl2): δ 15.4 (d, 1JPSi = 124.6 Hz). Mp: 78.8 °C.
Data for the minor isomer (24%) are as follows. 1H NMR (500 MHz,
CD2Cl2): δ 7.89−7.59 (m, 10H, P(C6H5)2*), 7.48−7.39 (m, 1H,
CHdipp*), 7.37−7.29 (m, 1H, CHdipp*), 7.24−7.19 (m, 1H, CHdipp*),
= 6.8 Hz, CH2), 45.3 (d, JCP = 9.6 Hz, CHbridgehead), 41.6 (d, JCP
=
=
3
3
1.2 Hz, CHbridgehead), 32.4 (d, JCP = 5.9 Hz, CH3tBu), 31.9 (d, JCP
5.9 Hz, CH3tBu), 28.4 (s, CHiPr), 28.3 (s, CHiPr), 27.1 (s, CH2), 25.3
(s, CH3iPr), 24.9 (d, JCP = 1.9 Hz, CH2), 24.6 (s, CH3iPr), 24.4 (s,
CH3iPr), 24.3 (s, CH3iPr), 5.3 (s, SiMe2), 3.7 (d, 3JCP = 1.4 Hz, SiMe2).
Cipso attached to the boron atom could not be detected. 31P NMR
(121 MHz, CD2Cl2): δ 21.8 (1JSiP = 237.4 Hz). 11B NMR (96 MHz,
CD2Cl2): δ −16.6 (s, BAr). 19F NMR (282 MHz, CD2Cl2): δ −133.0
(br, C−Fortho), −163.7 (t, JFF = 20.3 Hz, CAr−Fpara), −167.5 (t, JFF
=
=
18.3 Hz, CAr−Fmeta). 29Si NMR (60 MHz, CD2Cl2): δ 25.6 (d, 2JSiP
2.88 Hz, SiMe2), −21.6 (d, JSiP = 237.4 Hz, Si+). Anal. Calcd for
3.58 (s, 1H, CHbridgehead*), 2.98 (sept, JHH = 6.7 Hz, 1H, CHiPr),
1
3
G
https://dx.doi.org/10.1021/acs.organomet.0c00489
Organometallics XXXX, XXX, XXX−XXX

Organometallics
pubs.acs.org/Organometallics
Article
2.89−2.79 (br, 1H, CHiPr*), 2.89−2.79 (br, 1H, CHbridgehead*), 2.11−
1.91 (m, 2H, CH2*), 1.68−1.34 (m, 4H, 2 CH2*), 1.31 (d, 3JHH = 6.7
CHPh), 6.93−6.87 (m, 2H, CHPh), 6.39 (broad s, 1H, P−CH−O),
3.58 (sept, 3JHH = 6.9 Hz, 1H, CHiPr), 3.20 (sept, 3JHH = 6.7 Hz, 1H, 2
CHiPr), 2.92 (br, 2H, 2 CHbridgehead), 2.01−1.92 (m, 1H, CH2), 1.81−
1.70 (m, 1H, CH2), 1.58−1.48 (m, 2H, CH2), 1.40 (d, 3JPH = 6.9 Hz,
3H, CH3iPr), 1.37−1.28 (m, 9H, 3 CH3iPr), 1.27−1.23 (m, 1H, CH2),
1.17−1.10 (m, 1H, CH2), 0.67 (s, 3H, Si−CH3), 0.02 (s, 3H, Si−
CH3). 13C NMR (126 MHz, CD2Cl2): δ 177.9 (d, 2JCP = 5.2 Hz, N−
C), 148.6 (br d, JCF = 243.7 Hz, CAr−F), 147.6 (s, Cdipp), 146.8 (s,
3
Hz, 3H, CH3iPr), 1.26 (d, 3H, CH3iPr*), 1.20 (d, JHH = 6.7 Hz, 3H,
CH3iPr), 1.18 (d, 3JPH = 4.4 Hz, 3H, Si−CH3 overlapped with CH3iPr),
3
1.17 (d, JHH = 7.0 Hz, 3H, CH3iPr overlapped with Si−CH3). 13C
NMR (126 MHz, CD2Cl2): δ 187.3 (d, 2JCP = 13.9 Hz, N−C), 148.7
(br d, JCF = 241.7 Hz, CAr−F), 148.6 (s, Cdipp), 147.5 (s, Cdipp*), 138.7
(br d, JCF = 243.8 Hz, CAr−F), 136.7 (br d, JCF = 243.8 Hz, CAr−F),
135.3 (d, JCP = 3.5 Hz, CHPh), 135.1 (d, JCP = 3.4 Hz, CHPh), 133.3
(d, JCP = 11.3 Hz, CHPh), 133.1 (d, JCP = 11.3 Hz, CHPh), 131.4 (d,
CHPh*), 131.0 (d, CHPh*), 129.9 (s, CHdipp), 126.2 (s, CHdipp), 125.8
C
dipp), 138.6 (br d, JCF = 244.4 Hz, CAr−F), 136.6 (s, N−CDipp), 136.5
(br d, JCF = 244.4 Hz, CAr−F), 135.8 (d, JCP = 2.8 Hz, CHPh), 135.7
(d, JCP = 2.8 Hz, CHPh), 134.7 (d, JCP = 9.3 Hz, CHPh), 133.8 (d, JCP
=
1
9.1 Hz, CHPh), 131.2 (s, Cipso(benzaldehyde)), 130.6 (d, JCP = 12.2 Hz,
CHPh), 130.3 (d, JCP = 12.3 Hz, CHPh), 129.7 (d, JCP = 11.9 Hz,
(s, CHdipp), 124.5 (br, B−CAr), 118.8 (d, JCP = 76.4 Hz, P−CPh),
118.3 (d, 1JCP = 75.2 Hz, P−CPh), 87.0 (d, 1JCP = 73.7 Hz, C-P), 49.1
(d, CH2*), 45.5 (d, 2JCP = 8.8 Hz, CHbridgehead), 42.8 (s, CHbridgehead),
28.9 (s, 2 CHiPr), 28.5 (s, CH2), 26.5 (d, 3JC = 2.5 Hz, CH2), 25.8 (s,
CH3iPr), 25.3 (s, CH3iPr), 24.6 (s, CH3iPr), 24.4 (s, CH3iPr), 2.9 (d, 2JCP
CHPh), 129.6 (s, CHPh), 129.1 (d, JCP = 2.6 Hz, CHPh), 127.9 (d, JCP
=
4.8 Hz, CHPh), 126.2 (s, 2 CHdipp), 125.8 (s, 2 CHdipp), 124.4 (br, B−
CAr), 118.7 (d, 1JCP = 86.1 Hz, P−CPh), 116.3 (d, 1JCP = 83.0 Hz, P−
CPh), 90.0 (d, 1JCP = 91.5 Hz, C−P), 73.4 (d, 1JCP = 62.0 Hz, CH−O),
49.1 (d, 2JCP = 10.9 Hz, CHbridgehead), 47.1 (d, JCP = 5.7 Hz, CH2), 46.6
(d, 2JCP = 8.4 Hz, CHbridgehead), 28.7 (s, CHiPr), 28.6 (s, CHiPr), 27.9 (s,
CH2), 26.6 (d, 3JCP = 2.5 Hz, CH2), 25.1 (s, CH3iPr), 24.9 (s, CH3iPr),
24.8 (s, CH3iPr), 24.5 (s, CH3iPr), 0.5 (s, Si−CH3), −1.4 (s, Si−CH3).
31P NMR (202 MHz, CD2Cl2): δ 21.5 (s). 19F NMR (471 MHz,
CD2Cl2): δ −133.0 (br, CAr-Fortho), −163.7 (t, JFF = 20.4 Hz, CAr-
= 17.8 Hz, Si+−CH3). 31P NMR (202 MHz, CD2Cl2): δ −24.1 (1JPSi
=
117.4). 19F NMR (471 MHz, CD2Cl2): δ −132.9 (br, CAr−Fortho),
−163.6 (t, JFF = 20.4 Hz, CAr−Fpara), −167.4 (t, JFF = 18.1 Hz, CAr−
F
meta). 11B NMR (160 MHz, CD2Cl2): δ −16.6 (s, BAr). 29Si NMR
1
(99 MHz, CD2Cl2): δ 15.3 (d, JPSi = 117.4 Hz). All signals marked
with * are overlapped by signals of the major isomer.
Synthesis of 6. In a J. Young NMR tube, to a solution of 5f (50.0
mg, 0.042 mmol) in dichloromethane (0.3 mL) was added methyl
acrylate (3.78 μL, 0.042 mmol), and then the solution was warmed at
50 °C for 4 h. Then the solution was evaporated under vacuum and
the resulting crude product was washed with 3 × 0.3 mL of pentane.
F
para), −167.5 (t, JFF = 18.1 Hz, CAr-Fmeta). 11B NMR (160 MHz,
CD2Cl2): δ −16.6 (s, BAr). 29Si NMR (99 MHz, CD2Cl2): δ 9.5 (s).
Data for the minor isomer (32%) are as follows. 1H NMR (500 MHz,
CD2Cl2): δ 7.91−7.80 (m, 1H, CHPh), 7.78−7.68 (m, 1H, CHPh),
7.68−7.62 (m, 4H, CHPh), 7.51−7.40 (m, 3H, CHPh), 7.38−7.28 (m,
3H, CHPh), 7.23−7.15 (m, 2H, CHPh), 7.10−7.03 (m, 2H, CHPh),
6.85−6.80 (m, 2H, CHPh), 6.39 (broad s, 1H, P−CH−O), 3.27 (sept,
3JHH = 6.7 Hz, 1H, CHiPr), 3.20 (m, 1H, CHiPr), 2.92 (br, 1H,
CHbridgehead), 2.81 (br, 1H, CHbridgehead), 2.01−1.92 (m, 1H, CH2),
1.92−1.82 (m, 1H, CH2), 1.79−1.70 (m, 1H, CH2), 1.58−1.48 (m,
1H, CH2), 1.37−1.28 (m, 9H, 3 CH3iPr), 1.21 (d, 3JPH = 6.8 Hz, 3H,
CH3iPr), 1.17−1.10 (m, 1H, CH2), 1.03−0.96 (m, 1H, CH2), 0.85 (s,
3H, Si−CH3), 0.09 (s, 3H, Si−CH3). 13C NMR (126 MHz, CD2Cl2):
δ 177.7 (d, 2JCP = 5.2 Hz, N−C), 148.6 (br d, JCF = 243.7 Hz, CAr−F),
147.5 (s, Cdipp), 146.5 (s, Cdipp), 138.6 (br d, JCF = 244.4 Hz, CAr−F),
1
Product 6 was isolated as a white powder in 60% yield (32 mg). H
NMR (500 MHz, CD2Cl2): δ 7.83−7.53 (m, 8H, P(C6H5)2), 7.43−
7.36 (m, 1H, CHdipp), 7.32−7.25 (m, 2H, CHdipp overlapped by
P(C6H5)2)), 7.32−7.25 (m, 2H, P(C6H5)2 overlapped by CHdipp),
3
3
3
3.94 (ddd, 1H, JPH = 25.3 Hz, JHH = 6.2 Hz, JHH = 3.2 Hz, CH
C), 3.78 (ddd, 1H, 3JHH = 17.7 Hz, 2JPH = 14.3 Hz, 3JHH = 3.2 Hz, P−
CH2), 3.52 (ddd, 1H, 3JHH = 17.7 Hz, 2JPH = 14.3 Hz, 3JHH = 6.2 Hz,
3
P−CH2), 3.44 (s, 3H, O−CH3), 3.41 (sept, JHH = 6.9 Hz, 1H,
CHiPr), 3.11 (sept, JHH = 6.8 Hz, 1H, CHiPr), 2.93 (br, 1H,
3
CHbridgehead), 2.49 (br, 1H, CHbridgehead), 1.99−1.90 (m, 1H, CH2),
3
1.80−1.52 (m, 3H, CH2), 1.48−1.41 (m, 1H, CH2), 1.38 (d, JPH
=
6.9 Hz, 3H, CH3iPr), 1.31 (d, 3JPH = 6.8 Hz, 3H, CH3iPr), 1.27 (d, 3JPH
= 6.9 Hz, 3H, CH3iPr), 1.24 (d, 3JPH = 6.8 Hz, 3H, CH3iPr), 1.11−1.07
(m, 1H, CH2), 0.40 (s, 3H, Si−CH3), −0.04 (s, Si−CH3). 13C NMR
(126 MHz, CD2Cl2): δ 177.6 (d, 2JCP = 2.9 Hz, N−C), 156.9 (d, 3JCP
= 5.5 Hz, CHC−O), 148.5 (br d, JCF = 243.7 Hz, CAr−F), 147.6 (s,
137.1 (s, CDipp), 136.5 (br d, JCF = 244.4 Hz, CAr−F), 135.7 (d, JCP
=
2.8 Hz, CHPh), 135.4 (d, JCP = 3.0 Hz, CHPh), 134.8 (d, JCP = 9.8 Hz,
CHPh), 133.6 (d, JCP = 9.3 Hz, CHPh), 132.7 (s, ipso of
(C6H5)benzaldehyde), 131.0 (d, JCP = 11.9 Hz, CHPh), 130.8 (d, JCP
=
3.3 Hz, CHPh), 130.5 (d, JCP = 3.8 Hz, CHPh), 129.5 (s, CHPh), 129.3
(d, JCP = 3.1 Hz, CHPh), 126.9 (d, JCP = 4.2 Hz, CHPh), 125.8 (s,
C
C
dipp), 146.7 (s, Cdipp), 138.6 (br d, JCF = 244.4 Hz, CAr−F), 137.4 (s,
Dipp), 136.6 (br d, JCF = 244.4 Hz, CAr−F), 134.3 (d, JCP = 3.1 Hz,
1
CHdipp), 125.7 (s, CHdipp), 124.4 (br, ipso of BAr), 119.7 (d, JCP
=
=
=
1
1
CHPh), 133.9 (d, JCP = 2.8 Hz, CHPh), 131.9 (d, JCP = 10.2 Hz, CHPh),
131.3 (d, JCP = 8.7 Hz, CHPh), 130.3 (d, JCP = 11.9 Hz, CHPh), 130.1
(d, JCP = 13.0 Hz, CHPh), 129.5 (s, CHdipp), 128.6 (d, 1JCP = 91.3 Hz,
P−CPh), 125.9 (s, CHdipp), 125.6 (s, CHdipp), 123.7 (d, 1JCP = 89.6 Hz,
82.2 Hz, P−CPh), 115.2 (d, JCP = 87.4 Hz, P−CPh), 83.8 (d, JCP
1
2
93.5 Hz, C-P), 73.5 (d, JCP = 59.6 Hz, P−CH−O), 49.8 (d, JCP
2
10.5 Hz, CHbridgehead), 48.0 (d, JCP = 10.4 Hz, CHbridgehead), 46.0 (d,
JCP = 4.0 Hz, CH2), 28.7 (s, CHiPr), 28.5 (s, CHiPr), 28.3 (s, CH2),
26.4 (d, 3JCP = 2.5 Hz, CH2), 25.4 (s, CH3iPr), 25.0 (s, CH3iPr), 24.7 (s,
CH3iPr), 24.0 (s, CH3iPr), −1.7 (s, Si−CH3), −3.5 (s, Si−CH3). 31P
NMR (202 MHz, CD2Cl2): δ 22.2 (s). 19F NMR (471 MHz,
CD2Cl2): δ −133.0 (br, CAr−Fortho), −163.7 (t, JFF = 20.4 Hz, CAr−
1
2
P−CPh), 92.2 (d, JCP = 73.2 Hz, C−P), 67.8 (d, JCP = 10.6 Hz,
2
CHC), 56.0 (s, O−CH3), 52.1 (d, JCP = 12.9 Hz, CHbridgehead),
49.9 (d, 3JCP = 10.7 Hz, CHbridgehead), 46.9 (d, JCP = 5.8 Hz, CH2), 28.8
(s, CHiPr), 28.5 (s, CH2), 28.4 (s, CHiPr), 28.3 (d, 1JCP = 58.2 Hz, P−
CH2), 26.2 (d, 3JCP = 2.8 Hz, CH2), 25.5 (s, CH3iPr), 25.1 (s, CH3iPr),
24.8 (s, CH3iPr), 23.7 (s, CH3iPr), −0.8 (s, Si−CH3), −1.6 (s, Si−
CH3). Cipso attached to boron atom could not be detected. 31P NMR
(202 MHz, CD2Cl2): δ 20.9 (s). 19F NMR (471 MHz, CD2Cl2): δ
−133.0 (br, CAr−Fortho), −163.7 (t, JFF = 20.4 Hz, CAr−Fpara), −167.5
(t, JFF = 18.1 Hz, m of CAr−Fmeta). 11B NMR (160 MHz, CD2Cl2): δ
−16.6 (s, BAr). 29Si NMR (99 MHz, CD2Cl2): δ 5.0 (s).
F
para), −167.5 (t, JFF = 18.1 Hz, CAr−Fmeta). 11B NMR (160 MHz,
CD2Cl2): δ −16.6 (s, BAr). 29Si NMR (99 MHz, CD2Cl2): δ 8.9 (s).
ASSOCIATED CONTENT
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.organomet.0c00489.
Synthesis of 7. In a J. Young NMR tube, to a solution of 5f (50.0
mg, 0.042 mmol) in deuterated dichloromethane (0.3 mL) was added
benzaldehyde (4.3 μL, 0.042 mmol). The reaction immediately
proceeded to give adduct 7 as a mixture of two diastereomers in a
68:32 ratio. Suitable crystals for X-ray diffraction were obtained by
layering of pentane in dichloromethane. Product 7 was isolated as a
white powder in 66% yield (36 mg). Data for the major isomer (68%)
Spectroscopic and X-ray data (PDF)
Accession Codes
CCDC 2016527−2016532 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
1
are as follows. H NMR (500 MHz, CD2Cl2): δ 7.91−7.80 (m, 2H,
CHPh), 7.78−7.68 (m, 2H, CHPh), 7.68−7.62 (m, 4H, CHPh), 7.50−
7.40 (m, 3H, CHPh), 7.38−7.28 (m, 3H, CHPh), 7.23−7.15 (m, 2H,
H
https://dx.doi.org/10.1021/acs.organomet.0c00489
Organometallics XXXX, XXX, XXX−XXX

Organometallics
pubs.acs.org/Organometallics
Article
Pair Halogen Coordination of Silylium Ions? J. Am. Chem. Soc. 2011,
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
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AUTHOR INFORMATION
Corresponding Authors
■
́
Eddy Maerten − Universite de Toulouse, UPS, and CNRS,
LHFA UMR 5069, 31062 Toulouse, France; orcid.org/
Schmidtmann, M.; Muller, T.; Robert, F.; Landais, Y. Chiral Memory
̈
0000-0002-4876-7521; Email: maerten@chimie.ups-tlse.fr
in Silyl-Pyridinium and Quinolinium Cations. J. Am. Chem. Soc. 2020,
142, 564−572. (h) Wu, Q.; Roy, A.; Wang, G.; Irran, E.; Klare, H. F.
T.; Oestreich, M. Synthesis of a Counteranion-Stabilized Bis(silylium)
Ion. Angew. Chem., Int. Ed. 2020, 59, 10523−10526. (i) Muller, T.;
Kunzler, S.; Rathjen, S.; Ruger, K.; Wurdemann, M. S.; Wernke, M.;
Tholen, P.; Girschik, C.; Schmidtmann, M.; Landais, Y. Chiral
Chalcogenyl-Substituted Naphthyl- and Acenaphthyl-silanes and their
Cations. Chem. - Eur. J. 2020, DOI: 10.1002/chem.202002977.
(5) (a) Scott, V. J.; Celenligil-Cetin, R.; Ozerov, O. V. Room-
Temperature Catalytic Hydrodefluorination of C(sp3)−F Bonds. J.
Am. Chem. Soc. 2005, 127, 2852−2853. (b) Panisch, R.; Bolte, M.;
́
Tsuyoshi Kato − Universite de Toulouse, UPS, and CNRS,
LHFA UMR 5069, 31062 Toulouse, France; orcid.org/
0000-0001-9003-4455; Email: kato@chimie.ups-tlse.fr
Authors
́
Aymeric Dajnak − Universite de Toulouse, UPS, and CNRS,
LHFA UMR 5069, 31062 Toulouse, France
́
Nathalie Saffon-Merceron − Universite de Toulouse, UPS, and
CNRS, ICT FR2599, 31062 Toulouse, France
́
Antoine Baceiredo − Universite de Toulouse, UPS, and CNRS,
Muller, T. Hydrogen- and Fluorine-Bridged Disilyl Cations and Their
̈
LHFA UMR 5069, 31062 Toulouse, France
Use in Catalytic C−F Activation. J. Am. Chem. Soc. 2006, 128, 9676−
9682. (c) Douvris, C.; Ozerov, O. V. Hydrodefluorination of
Perfluoroalkyl Groups Using Silylium-Carborane Catalysts. Science
2008, 321, 1188−1190. (d) Douvris, C.; Nagaraja, C. M.; Chen, C.-
H.; Foxman, B. M.; Ozerov, O. V. Hydrodefluorination and Other
Hydrodehalogenation of Aliphatic Carbon−Halogen Bonds Using
Silylium Catalysis. J. Am. Chem. Soc. 2010, 132, 4946−4953.
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.organomet.0c00489
Author Contributions
A.D. performed all synthetic work, while N.S.-M. performed all
X-ray structural studies.
(e) Lu
forming reaction between aliphatic fluorohydrocarbons and arylsi-
lanes. Appl. Organomet. Chem. 2010, 24, 533−537. (f) Luhmann, N.;
Hirao, H.; Shaik, S.; Mu
hmann, N.; Panisch, R.; Muller, T. A catalytic C-C bond-
̈ ̈
Notes
The authors declare no competing financial interest.
̈
̈
ller, T. Disilylfluoronium IonsSynthesis,
Structure, and Bonding. Organometallics 2011, 30, 4087−4096.
(g) Allemann, O.; Duttwyler, S.; Romanato, P.; Baldridge, K. K.;
Siegel, J. S. Proton-Catalyzed, Silane-Fueled Friedel-Crafts Coupling
of Fluoroarenes. Science 2011, 332, 574−577. (h) Stahl, T.; Klare, H.
F. T.; Oestreich, M. Main-Group Lewis Acids for C−F Bond
Activation. ACS Catal. 2013, 3, 1578−1587. (i) Kordts, N.; Borner,
ACKNOWLEDGMENTS
The Agence Nationale de la Recherche (ANR-16-CE07-0018-
■
̀
́
01) and the Ministere de l’Enseignement Superieur et de la
Recherche are gratefully acknowledged for a Ph.D. grant to
́
A.D. The authors thank the CNRS and the Universite de
Toulouse, UPS, for financial support.
C.; Panisch, R.; Saak, W.; Mu
Germylsilyl Cations. Organometallics 2014, 33, 1492−1498. (j) Kordts,
N.; Kunzler, S.; Rathjen, S.; Sieling, T.; Groβekappenberg, H.;
Schmidtmann, M.; Muller, T. Silyl Chalconium Ions: Synthesis,
̈
ller, T. Hydrogen-Bridged Digermyl and
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