Reactions of [Cu(X)(BPEP-Ph)] (X = PF6, SbF6) with silyl compounds. Cooperative bond activation involving non-coordinating anions

Article abstract of DOI:10.1039/c5dt03166d

Bond activation of silyl compounds, assisted by the cooperative action of non-coordinating anions, is achieved using Cu(i) complexes coordinated with a PNP-pincer type phosphaalkene ligand, [Cu(X)(BPEP-Ph)] (X = PF₆ (1a), SbF₆ (1b); BPEP-Ph = 2,6-bis[1-phenyl-2-(2,4,6-tri-tert-butylphenyl)-2-phosphaethenyl]pyridine). Complexes 1a and 1b react with Me₃SiCN to form Me₃SiF and Cu(i) cyanide complexes of the formula [Cu(CN-EF₅)(BPEP-Ph)] (E = P (2a), Sb (2b)), in which the CN ligand is associated with the EF₅ group arising from EF₆^-. Formation of the intermediary isonitrile complex [Cu(CNSiMe₃)(BPEP-Ph)]⁺SbF₆^- (3b) is confirmed by its isolation. Thus, a two-step reaction process involving coordination of Me₃SiCN, followed by nucleophilic attack of SbF₆^- on the silicon atom of 3b is established for the conversion of 1b to 2b. Complex 1b cleaves the H-Si bond of PhMe₂SiH as well. The isolation and structural identification of [Cu(BPEP-Ph)]⁺BAr^F₄^- (1c) (BAr^F₄ = B{3,5-(CF₃)₂C₆H₃}₄) as a rare example of a T-shaped, three-coordinated Cu(i) complex is reported.

Full text of DOI:10.1039/c5dt03166d

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Reactions of [Cu(X)(BPEP-Ph)] (X = PF , SbF ) with
6
6
silyl compounds. Cooperative bond activation
Cite this: DOI: 10.1039/c5dt03166d
involving non-coordinating anions†
a
b
b
Yumiko Nakajima,* Takahiro Tsuchimoto, Yung-Hung Chang,
b
b
Katsuhiko Takeuchi and Fumiyuki Ozawa*
Bond activation of silyl compounds, assisted by the cooperative action of non-coordinating anions, is
achieved using Cu(I) complexes coordinated with a PNP-pincer type phosphaalkene ligand, [Cu(X)-
(
BPEP-Ph)] (X = PF
ethenyl]pyridine). Complexes 1a and 1b react with Me
the formula [Cu(CN-EF )(BPEP-Ph)] (E = P (2a), Sb (2b)), in which the CN ligand is associated with the EF
group arising from EF −
3b) is confirmed by its isolation. Thus, a two-step reaction process involving coordination of Me
followed by nucleophilic attack of SbF − on the silicon atom of 3b is established for the conversion of 1b to
6
(1a), SbF
6
(1b); BPEP-Ph = 2,6-bis[1-phenyl-2-(2,4,6-tri-tert-butylphenyl)-2-phospha-
3
SiCN to form Me SiF and Cu(I) cyanide complexes of
3
5
5
+
−
6
. Formation of the intermediary isonitrile complex [Cu(CNSiMe
3
)(BPEP-Ph)] SbF
6
(
3
SiCN,
Received 17th August 2015,
6
Accepted 25th September 2015
2
b. Complex 1b cleaves the H–Si bond of PhMe
2
SiH as well. The isolation and structural identification of
DOI: 10.1039/c5dt03166d
+
F −
F
4 4 3 2 6 3 4
[Cu(BPEP-Ph)] BAr
(1c) (BAr = B{3,5-(CF ) C H } ) as a rare example of a T-shaped, three-coordinated
www.rsc.org/dalton
Cu(I) complex is reported.
bonding interactions with PF −
and SbF −
as non-coordinating
6
6
Introduction
anions in nonpolar solvents as well as in the solid state
7
Phosphaalkenes with a PvC bond possess an extremely low- (Scheme 1). DFT calculations have revealed that BPEP-Ph as a
lying π* orbital and exhibit strong π-acceptor properties strong π-acceptor produces a highly electron-deficient Cu(I)
1
−
−
towards transition metals. We have documented that this par- center, which has a strong affinity for PF
6 6
and SbF .
ticular ligand property often provides interesting structures
and reactivities in late transition metal complexes.
This paper describes bond activation of silyl compounds
induced by 1a and 1b. We anticipated that the highly electron-
2
–4
Our current interest is focused on PNP-pincer complexes deficient Cu(I) center in these complexes could enhance the
supported by 2,6-bis[1-phenyl-2-(2,4,6-tri-tert-butylphenyl)-2-
phosphaethenyl]pyridine (BPEP-Ph), in which two PvC bonds
are linked to 2,6-positions of pyridine. We have demonstrated
that this novel tridentate ligand with a highly delocalized
π-electron system successfully stabilizes 3d metal complexes in
low oxidation states. Representative examples include Fe(I) com-
5
plexes with a 15-electron configuration, which exhibit a unique
6
redox behavior. We have also communicated that Cu(I) centers
6 6
in [Cu(X)(BPEP-Ph)] (X = PF (1a), SbF (1b)) establish strong
a
Interdisciplinary Research Center for Catalytic Chemistry, National Institute of
Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565,
Japan. E-mail: yumiko-nakajima@aist.go.jp
b
International Research Center for Elements Science (IRCELS), Institute for Chemical
Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
E-mail: ozawa@scl.kyoto-u.ac.jp
†
Electronic supplementary information (ESI) available: Details of crystal struc-
ture determination and DFT calculations. CCDC 1417449 and 1417450. For ESI
and crystallographic data in CIF or other electronic format see DOI: 10.1039/
c5dt03166d
Scheme 1 Preparation and solution behavior of Cu(I) BPEP-Ph
complexes.
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electrophilicity of silyl substrates to a considerable extent and
Complex 1c exhibited a singlet signal assignable to free
F −
19
31
1
facilitate the external attack of a nucleophile. Actually, we found BAr 4 (δ −62.9) in the F NMR spectrum. The P{ H} NMR
that 1a and 1b cause N–Si bond cleavage of Me SiNC under signal was observed at δ 214.4 in CD Cl , and this value was
as “non-coordinating very close to that of 1a and 1b (δ 213.3). Moreover, the H NMR
3
2
2
−
−
1
mild conditions, where PF
6
and SbF
6
+
anions” act as nucleophiles. We also present the crystal structure spectrum of the [Cu(BPEP-Ph)] moiety was almost identical to
of a rare example of a T-shaped, three-coordinated Cu(I) that of 1a and 1b. Thus, the ionic dissociation of 1a and 1b to
+
F −
F
complex, [Cu(BPEP-Ph)] BAr
4 4 3 2 6 3 4 2 2
(1c) (BAr = B{3,5-(CF ) C H } ). form the T-shaped species in CD Cl was evidenced.
Bond activation of silyl compounds by 1a and 1b
3 3
We previously reported that the Si–N bond of Me SiN is acti-
+
−
−
Results and discussion
Solution structures of [Cu(X)(BPEP-Ph)]
vated by 1a and 1b to form [Cu
2
(BPEP-Ph)
2
(μ-N
PF6 and SbF6−), respectively (eqn (1)). These reactions very
probably involve the by-production of Me SiF and EF (E = P
and Sb). However, while the formation of Me SiF was con-
3
)] X (X
=
−
7
3
5
While 1a and 1b are isolated as crystalline compounds with
tight bonding interactions between Cu and X, they show the
same NMR spectra, except for X, in CD Cl as a polar solvent.
2 2
3
firmed by NMR spectroscopy, EF could not be detected in the
reaction systems. On the other hand, we noticed that the reac-
3
SiCN present all product components including
EF , which is found in an associated form with a cyanido
5
7
Thus, we considered that both complexes change into the
tions with Me
+
2 2
T-shaped species [Cu(BPEP-Ph)] in CD Cl by ionic dis-
5
sociation. However, because a structually well-defined Cu(I)
ligand arising from the activation of the Me
3
Si–CN bond
8
complex with a T-shaped geometry is very rare, we attempted
(
eqn (2)).
+
F −
to isolate [Cu(BPEP-Ph)] using bulky BAr
4
as a counter anion.
Following the synthetic procedures for 1a and 1b, the
+
F −
complex [Cu(BPEP-Ph)] BAr
(1c) was prepared by anionic
4
F
exchange of [CuBr(BPEP-Ph)] with NaBAr
4 2 2
in CH Cl . A single
crystal suitable for X-ray diffraction analysis was grown from a
ð1Þ
CH Cl solution layered with hexane. Fig. 1 presents the X-ray
2
2
structure of 1c, adopting a three-coordinated, T-shaped con-
figuration around Cu. The Cu atom is coordinated only with
BPEP-Ph. The interatomic distance between Cu and the
F
nearest F atom of BAr
4
was 4.46 Å; this value is much larger
9
than the sum of the van der Waals radii of Cu and F (2.52 Å).
The lengths of Cu–P1 (2.206(1) Å), Cu–P2 (2.216(1) Å), and
Cu–N (2.074(3) Å) are in the normal range of dative covalent
ð2Þ
7
,8,10
bonds found in PNP-pincer complexes of Cu(I).
The P1–
Cu–P2 angle is 167.11(5)°, whereas the P1–Cu–N and P2–Cu–N
angles are 84.5(1) and 84.5(1)°, respectively. The sum of the
three angles around Cu is 361.9°, the value of which is almost
the same as that previously reported for a T-shaped Cu(I)
complex (362.3°). Hence, the three-coordinated, T-shaped
structure of 1c was confirmed.
Complex 1a rapidly reacted with Me SiCN in CD Cl at
3
2
2
8
ambient temperature to give 2a quantitatively, as confirmed by
NMR spectroscopy. The by-production of Me SiF (δ 0.23,
3
H
δF −157.9) was observed as well. Complex 2a was isolated as a
light yellow solid in 68% yield. Complex 1b was less reactive
than 1a; however, the reaction with Me
3
SiCN proceeded at
0 °C for 1 h, and the cyanide complex 2b was obtained in
3% yield, along with Me SiF. Although complexes 2a and 2b
5
4
3
did not give a satisfactory elemental analysis, they were
unequivocally characterized by IR and NMR spectroscopy. The
ν(CN) absorption bands of 2a and 2b were observed at 2196
and 2158 cm− , respectively. These wavenumbers are clearly
1
−
1 11
higher than those of common Cu(I) cyanides (ca. 2100 cm ),
reflecting the association with PF and SbF as strong Lewis
5
5
1
2
acids.
Fig. 1 ORTEP drawing of 1c with 50% probability ellipsoids. Hydrogen
31
1
The P{ H} NMR spectrum of 2a exhibited two sets of
signals at δ 264.1 and −151.6. The former signal due to
BPEP-Ph appeared in the typical region for phosphaalkene
ligands. On the other hand, the latter signal assignable to the
F
atoms, BAr
4 2 2
anions and a crystal solvent (CH Cl ) are omitted for
clarity. Selected bond distances (Å) and angles (°): Cu–P1 = 2.206(1),
Cu–P2 = 2.216(1), Cu–N = 2.074(3), P1–C1 = 1.691(4), P2–C2 = 1.711(4),
P1–Cu–N = 84.5(1), P2–Cu–N = 84.5(1), P1–Cu–P2 = 167.09(5).
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5
PF group associated with the CN ligand was split into a
doublet of quintets, due to the coupling with fluorine nuclei
1
( JPF = 774 and 745 Hz). This coupling pattern was consistent
with the octahedral configuration around phosphorus, linked
to one fluorine atom at the apical position and four fluorine
1
9
atoms at the equatorial positions. Indeed, the F NMR spec-
1
trum of 2a displayed two sets of signals at δ −83.6 (dq, JPF
=
2
1
2
7
74 Hz, J = 62 Hz) and −53.1 (dd, J = 745 Hz, J = 62
FF
PF
FF
Hz) in an intensity ratio of 1 : 4, which are assigned to the
apical and equatorial fluorine atoms, respectively.
3
1
1
The P{ H} NMR signal of 2b (δ 262.3) was observed in the
normal range of phosphaalkene complexes as well. Although
Fig. 2 ORTEP drawing of 2b with 50% probability ellipsoids. Hydrogen
atoms are omitted for clarity. Selected bond distances (Å) and angles (°):
1
9
the F NMR signals at δ −131.0 and −108.0 were significantly
1
21
broadened due to the quadrupole moment of antimony ( Sb, Cu–C1 = 1.886(7), Cu–P1 = 2.321(2), Cu–P2 = 2.310(2), Cu–N2 = 2.021
1
23
I = 5/2, Sb, I = 7/2) and were therefore unavailable for struc- (5), C1–N1 = 1.180(8), N1–Sb = 2.043(6), Sb–F1 = 1.843(4), Sb–F2 =
1
1
.858(4), Sb–F3 = 1.849(4), Sb–F4 = 1.847(4), Sb–F5 = 1.861(5), P1–C2 =
.690(6), P2–C3 = 1.705(6), N–Cu–C1 = 126.2(2), P1–Cu–P2 = 135.95
5
tural assignment, the structure associated with the SbF group
could be confirmed by X-ray diffraction analysis (vide infra).
Complex 1b cleaved the Si–H bond of hydrosilanes. For
(7), Cu–C1–N1 = 178.5(6), C1–N1–Sb = 174.5(6), N1–Sb–F1 = 88.3(2),
N1–Sb–F2 = 90.2(2), N1–Sb–F3 = 89.1(2), N1–Sb–F4 = 87.4(2), N1–Sb–
instance, the reaction with PhMe
2
SiH at 40 °C formed bis F5 = 178.6(2).
(
phosphaethenyl)pyridinium (87%) and PhMe SiF (78%),
2
along with insoluble materials (eqn (3)). It is likely that the
pyridinium salt is eliminated from the Cu(I) hydride of the
+
−
formula [CuH(BPEP-Ph)] SbF , generated by Si–H bond clea-
6
vage. It was also confirmed that the reaction of 1b with
PhMe SiD produces a pyridinium salt deuterated at the nitro-
2
gen atom selectively.
ð3Þ
X-ray crystal structure of 2b
Fig. 2 shows the X-ray structure of [Cu(CN-SbF
5
)(BPEP-Ph)]
(
2b), which adopts a distorted tetrahedral configuration
3
Scheme 2 Bond activation of Me SiCN promoted by 1a and 1b.
around Cu. A similar structure has been observed for four-co-
1
0
ordinated Cu(I) complexes with a pincer ligand. The Cu–N2
length (2.021(5) Å) is in the typical range for Cu(I) complexes.
The Cu–P1 and Cu–P2 bonds (2.321(2) and 2.310(2) Å) are
slightly longer than those in PNP-pincer analogues so far
known to undergo 1,2-silyl group migration on transition
15
metals, the formation of isonitrile intermediates 3a and 3b,
7
,8,10
reported.
The Cu–C1 and C1–N1 bond lengths (1.886(7)
instead of nitrile homologues, is presumed. Actually, complex
1
3
and 1.180(8) Å) are ordinary for Cu(I) complexes, and the Cu–
C1–N1 bond (178.5(6)°) retains its linearity. On the other
hand, the N1–Sb bond (2.043(6) Å) is clearly shorter than that
of C N –SbF (2.213(5) Å) and pyrazine–SbF5 (2.172(5) Å).
The Sb atom adopts a distorted octahedral configuration, and
3
b could be prepared by the treatment of 1b with Me
room temperature, and isolated as a light orange compound in
3% yield. The IR spectrum exhibited the ν(CN) absorption
3
SiCN at
8
1
4
–1
2
2
5
band at 2156 cm , and this value is consistent with the iso-
nitrile coordination. Complex 3b was also examined by X-ray
the Sb–F bond lengths (1.843(4)–1.861(5) Å) are in the typical
range for nitrogen-coordinated SbF groups.
diffraction analysis. While the data quality was low (R = 0.1713),
1
1
4
5
the core structure of 3b could be confirmed (see the ESI†).
Isonitrile complexes 3a and 3b then undergo nucleophilic
attack of PF6− and SbF6− ions, respectively, on the silicon atom
3
Bond activation process of Me SiCN
Scheme 2 illustrates a plausible process for the formation of (Aa and Ab), leading to N–Si bond cleavage of the Me
3
SiNC
2
a and 2b from 1a and 1b, respectively. The first step is the ligand. Finally, [Cu(CN)(BPEP-Ph)] thus generated combines
coordination of Me SiCN to 1a and 1b. Since Me SiCN is with PF
and SbF
to form 2a and 2b, respectively.
3
3
5
5
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1
The differences in the relative stability between 3a
H NMR spectra were recorded at 25 °C on a Bruker Avance
1
13
and [2a + Me SiF] and 3b and [2b + Me SiF] were evaluated 400 spectrometer ( H NMR, 400.13 MHz;
SiF] 100.62 MHz; F NMR, 376.46 MHz; P NMR, 161.98 MHz).
was an exothermic process by 4.6 kcal mol , whereas that Chemical shifts are reported in δ (ppm), referenced to H (of
C
NMR,
3
3
1
9
31
by DFT calculations. The conversion of 3a to [2a + Me
3
−1
1
−
1
13
of 3b to [2b + Me SiF] was exothermic by 9.2 kcal mol
.
residual solvent signals) and C signals of deuterated solvents
3
1
9
Principally, the exothermicity observed for both systems must as internal standards or to the F signal of C
6
F
6
(δ 163.0) and
(δ 0.0) as external standards.
On the other hand, the IR spectra were recorded on a Jasco FT/IR-4100 spectrometer.
additional stability of 2b would be derived from the higher Elemental analysis was performed by the ICR Analytical
3
1
3 3 4
be due to the formation of Me SiF with an extremely strong to the P signal of 85% H PO
−1 16
Si–F bond (158 kcal mol ).
association energy of SbF
5
than PF
5
to the CN ligand in Laboratory, Kyoto University.
[
Cu(CN)(BPEP-Ph)], which is caused by the higher Lewis
1
2
5
acidity of SbF .
Preparation of 1c
It should be noted that the thermodynamic features associ-
F
ated with the conversion of isonitrile complexes (3a and 3b) to A suspension of NaBAr (28.0 mg, 0.032 mmol) in CH Cl
2
4
2
cyanide complexes (2a and 2b) are inconsistent with the reac- (3 mL) was added to a solution of [CuBr(BPEP-Ph)] (30.0 mg,
tivity order of the starting complexes (1a and 1b). Thus, it is 0.032 mmol) at room temperature. The mixture was stirred at
reasonable that the much higher reactivity of 1a than 1b room temperature for 1 h, and concentrated to dryness under
3
towards Me SiCN is caused due to a kinetic reason. A plausible vacuum. The residue was extracted with toluene (1 mL) and fil-
explanation may be found in the large difference in the fluor- tered through a Celite pad to remove the precipitate of NaBr
−
−
ide ion affinity between PF (pF = 9.49) and SbF5 (pF
=
formed in the system. The filtrate was concentrated to dryness
is reluctant to eliminate F , compared under reduced pressure, dissolved in CH Cl /hexane, and
is much less reactive stored at −35 °C to give brown crystals of 1c (52.0 mg,
0.030 mmol, 94%).
5
1
2
−
−
1
2.03); namely, SbF
6
2
2
−
with PF
6
−, and therefore 1b with SbF
6
than 1a with PF6−
.
1
t
t
2 2
1c: H NMR (CD Cl ): δ 1.33 (s, 18H, Bu), 1.57 (s, 36H, Bu),
6.75 (d, J = 7.4 Hz, 4H, Ar), 7.10 (t, J = 7.4 Hz, 4H, Ar),
7
.23–7.21 (m, 2H, Ar), 7.27–7.25 (m, 2H, Ar), 7.39 (s, 4H, Ar),
F
Conclusions
7.56 (s, BAr
4
, 4H), 7.66 (t, J = 8.3 Hz, 1H, Ar), 7.73 (s, 8H,
F
13
1
4 2 2
BAr ). C{ H} NMR (CD Cl ): δ 31.5, 34.6, 35.6, 39.2, 118.0,
We have demonstrated that [Cu(X)(BPEP-Ph)] (X = PF6 (1a),
SbF6 (1b)) bearing a PNP-pincer type phosphaalkene ligand
1
1
22.1, 124.1, 125.2, 125.6, 128.8, 129.0, 129.4, 130.2, 135.4,
37.0, 140.9, 155.5, 157.5, 157.7, 162.3, 181.2. P{ H} NMR
31
1
(BPEP-PH) led to the bond activation of Me
3 2 2
SiCN in CD Cl ,
1
9
(
CD
2 2 2 2
Cl ): δ 214.4 (br). F NMR (CD Cl ): δ −62.9 (s). Anal.
giving Cu(I) cyanides of the formula [Cu(CN-EF )(BPEP-Ph)]
5
calcd for C H BCuF NP : C, 60.23; H, 4.82; N, 0.81. Found:
C, 60.11; H, 5.11; N, 0.80.
8
7
83
24
2
(E = P (2a), Sb (2b)), along with the by-production of Me SiF.
3
The reactions proceed via coordination of Me
3
SiCN to give the
isocyanide complexes [Cu(CNSiMe )(BPEP-Ph)]X (X = PF (3a),
3
6
SbF (3b)), followed by Si–N bond cleavage caused by nucleo-
6
Reaction of 1a with Me SiCN
3
−
−
philic attack of PF
6 6
and SbF on the silicon atom. Although
The compounds [CuBr(BPEP)] (15.0 mg, 0.016 mmol) and
AgPF6 (4.7 mg, 0.019 mmol) were mixed in toluene (1 mL) at
PF6 and SbF6− as non-coordinating anions are known to be
−
poorly nucleophilic, complexes 1a and 1b smoothly react with
Me SiCN under mild conditions. This is probably because the
3
strong π-accepting ability of BPEP-Ph reduces the electron
density of the Cu–CN–SiMe3 moiety, and thus facilitates the
novel bond activation process involving cooperative action of
the non-coordinating anions.
7
room temperature. The solution was filtered through a Celite
pad to remove AgBr and unreacted AgPF
6 3
. Me SiCN (4 μL,
0.032 mmol) was added to the filtrate. The solution turned
light orange immediately. The solution was concentrated to
dryness, and the residue was washed with hexane, extracted
with toluene, and filtered through a Celite pad. The filtrate
was concentrated to dryness under vacuum to give 2a as a light
yellow solid (11.0 mg, 0.011 mmol, 68%).
1
t
t
2
a: H NMR (CD Cl ): δ 1.34 (s, 18H, Bu), 1.48 (s, 36H, Bu),
2 2
Experimental
6.66 (brs, 4H, Ar), 7.08 (br, 4H, Ar), 7.14 (m, 2H, Ar), 7.27 (d,
All manipulations were performed under a dry and oxygen-free 2H, J = 6.8 Hz, Ar), 7.36 (s, 4H, Ar), 7.63 (t, 1H, J = 7.8 Hz, Ar).
1
3
1
dinitrogen atmosphere using Schlenk techniques or a glove
C{ H} NMR (CD Cl ): δ 31.7, 34.5, 35.7, 39.1, 123.2, 128.3,
2 2
box. Solvents were dried over sodium/benzophenone ketyl 129.0, 129.7, 129.9, 137.9, 138.3, 153.9, 157.2, 157.6, 158.6,
1
3
(
toluene, C
6 6 2 2 2 2 2
D ) or CaH (hexane, CH Cl , CD Cl ) and dis- 174.9. The C NMR signal of CN was obscure due to low
F
31
1
1
tilled. CuBr, NaBAr , AgPF , Me SiCN, PhMe SiH and tri- signal intensity. P{ H} NMR (CD Cl ): δ −151.6 (dq, JPF
methoxybenzene were obtained from commercial sources and 745, 774 Hz, PF
used without purification. BPEP-Ph and [CuBr(BPEP-Ph)] were (dd, 4F, JPF = 745 Hz, JFF = 62 Hz), −83.6 (dq, 1F, JPF = 774
=
4
6
3
2
2
2
1
9
5
), 264.1 (brs, PvC). F NMR (CD
2
Cl
2
): δ −53.1
1
2
1
5
,7
2
−1
prepared as previously reported.
Hz, J = 62 Hz). IR (ATR): 2196 cm (νCN).
FF
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Reaction of 1b with Me
3
SiCN
immediately. The solution was concentrated to dryness to give
a solid product of 3b (7.6 mg, 0.0063 mmol, 83%).
To an NMR sample tube were charged a CD
2
Cl
2
solution
1
t
3
b: H NMR (CD
2
Cl
2
): δ 0.48 (s, 9H, Me
3
), 1.35 (s, 18H, Bu),
(0.4 mL) of 1b (7.1 mg, 0.0064 mmol) and then Me SiCN (2 μL,
3
t
1
7
7
3
1
.46 (s, 36H, Bu), 6.65 (brs, 4H, Ar), 7.11 (t, 4H, J = 7.0 Hz, Ar),
0
1
.016 mmol). The solution was allowed to stand at 50 °C for
h, and then examined by NMR spectroscopy. The formation
.21 (m, 2H, Ar), 7.30 (d, 2H, J = 7.6 Hz, Ar), 7.37 (s, 4H, Ar),
1
3
1
.68 (t, 1H, J = 7.8 Hz, Ar). C{ H} NMR (CD
2 2
Cl ): δ −1.69,
3 H F
of Me SiF (δ 0.23, δ −157.9) was observed. The solution was
1.4, 34.6, 35.5, 39.0, 123.4, 123.9, 126.4, 128.3, 128.5, 129.7,
concentrated to dryness, and the residue was extracted with
toluene (1 mL) and filtered through a Celite pad. The filtrate
was concentrated and stored at −35 °C to give a light yellow
crystalline solid of 2b (3.1 mg, 0.0028 mmol, 43%).
1
3
37.6, 138.2, 154.3, 156.7, 157.4, 175.5. The C NMR signal of
3
1
1
CN was obscure due to low signal intensity. P{ H} NMR
2 2
CD Cl
, RT): δ 262.3 (brs). IR (ATR): 2156 cm− (νCN).
1
(
1
t
2
b: H NMR (CD
Bu), 6.67 (brs, 4H, Ar), 7.08 (brs, 4H, Ar), 7.15 (m, 2H, Ar), 7.23
d, 2H, J = 7.6 Hz, Ar), 7.36 (s, 4H, Ar), 7.64 (t, 1H, J = 7.9 Hz,
2 2
Cl ): δ 1.33 (s, 18H, Bu), 1.48 (s, 36H,
t
X-ray crystal structure determination
(
1
3
1
t
t
The intensity data for 1c and 3b were collected on a Rigaku
Mercury CCD diffractometer with graphite-monochromated
Mo Kα radiation (λ = 0.71070 Å). For 2b, synchrotron radiation
experiment (λ = 0.71069 Å) was carried out at the BL38B1 of
SPring-8 with the approval of the Japan Synchrotron Radiation
Research Institute (JASRI) (Proposal No. 2010B1488). The data
sets were corrected for Lorentz and polarization effects and
absorption. The structures were solved by direct methods
Ar). C{ H} NMR (CD
2
Cl
Bu), 39.2 (s, Bu), 123.7 (br, Ar), 125.8 (s, Ar), 128.4 (s, Ar),
28.7 (s, Ar), 129.5 (s, Ar), 129.8 (s, Ar), 138.3 (s, Ar), 138.6 (s,
Ar), 154.4 (s, Ar), 157.1 (s, Ar), 157.7 (s, Ar), 175.7 (brs, PvC).
2
): δ 31.6 (s, Bu), 34.6 (s, Bu), 35.6 (s,
t
t
1
1
3
The C NMR signal of CN was obscure due to low signal inten-
sity. P{ H} NMR (CD Cl ): δ 263.5 (brs). F NMR (CD Cl ):
3
1
1
19
2
2
2
2
−
1
δ −108.0 (br, 4F), −131.0 (br, 1F). IR (ATR): 2158 cm (νCN).
1
7
2
(
(
SHELXS-97)
and refined on
F
for all reflections
Reaction of 1b with PhMe SiH
2
18
SHELXL-97). Anisotropic refinement was applied to all non-
To an NMR sample tube was charged a CD Cl solution
2
2
hydrogen atoms. Hydrogen atoms were placed at the calculated
positions. The crystallographic data and the summary of solu-
tion and refinement are listed in Table S1 (see the ESI†).
Further information has been deposited with the Cambridge
Crystallographic Data Centre (CCDC reference numbers
(0.4 mL) of 1b (12.0 mg, 0.011 mmol). PhMe SiH (20 μL,
2
0
.013 mmol) was added, and the solution was allowed to stand
at 40 °C for 24 h. The formation of PhMe SiF (0.0086 mmol,
2
1
7
8%) was confirmed by H NMR analysis using trimethoxy-
benzene (1.2 mg, 0.0071 mmol) as an external standard. The
solution was concentrated to dryness, and the residue was
washed with hexane (2 mL × 3), extracted with toluene, and fil-
tered through a Celite pad. The filtrate was concentrated to
1
417449 for 1c and 1417450 for 2b). The structure of 3b could
not be fully refined due to poor quality of the diffraction data.
+
−
dryness to give [H-BPEP-Ph] SbF (10.0 mg, 0.0096 mmol, DFT calculations
6
1
t
t
8
6
2
1
7%). H NMR (CD Cl ): δ 1.24 (s, 18H, Bu), 1.36 (s, 36H, Bu),
2 2
All calculations were carried out with the Gaussian 09 program
package. Geometry optimization was performed by the DFT
method without any symmetry constraints, where the B3PW91
functional was employed, using the model compounds
.45 (d, 4H, J = 7.2 Hz, Ar), 6.96 (t, 4H, J = 7.8 H, Ar), 7.07 (t,
H, J = 7.4 Hz, Ar), 7.21 (s, 4H, Ar), 8.22 (br, 2H, Ar), 8.31 (t,
19
1
3
1
H, J = 8.0 Hz, Ar), 10.74 (br, 1H, NH). C{ H} NMR (CD Cl ):
2
2
δ 31.3, 34.4, 35.4, 38.7, 123.1, 123.2, 129.3, 129.4, 129.6, 130.1,
36.0, 146.3, 153.5, 154.7, 155.9, 166.9. Anal. calcd for
C H NP SbF : C, 63.22; H, 6.95; N, 1.34. Found: C, 62.80; H,
[Cu(CNSiMe )(BPEP-Ph′)],
[Cu(CN-PF )(BPEP-Ph′)]
and
3
5
1
[Cu(CN-SbF
5
)(BPEP-Ph′)] (BPEP-Ph′
=
2,6-bis(2-mesityl-2-
5
5
72
2
6
phosphaethenyl)pyridine). The Cu and Sb atoms were
described with the SDD basis set and the LANL2DZdp basis
set, respectively. The 6-311G(d) basis sets were applied to P, N,
Si and the C atom of CN. The 6-311G basis sets were applied to
other C and H atoms. The core electrons of Cu and Sb were
replaced with effective core potentials (ECPs).
6
.85; N, 1.36.
Reaction of 1b with PhMe SiD
2
Complex 1b (12.7 mg, 0.012 mmol) was similarly treated with
PhMe
2
SiD (2.4 mg, 0.016 mmol) instead of PhMe
2
SiH, and
+
−
[
D-BPEP-Ph] SbF
6
(10.4 mg, 0.0099 mmol, 83%) was isolated.
1
The H NMR spectrum showed the disappearance of the pyri-
2
dinium proton signal (δ 10.74). Instead, the H NMR spectrum
revealed the formation of the deuterated product Acknowledgements
+
−
[
D-BPEP-Ph] SbF .
6
This work was supported by MEXT Grant-in-Aid for Scientific
Research on Innovative Areas “Stimuli-responsive Chemical
Species” (no. 15H00967 (Y.N.) and 24109010 (F.O.)) and by
Preparation of 3b
A CD Cl
charged into an NMR sample tube, and Me
2
2
solution (0.4 mL) of 1b (8.5 mg, 0.0076 mmol) was KAKENHI (no. 26288050 (F.O.)) from JSPS. We are grateful to
SiCN (5.0 μL, Professor Shigeyoshi Sakaki (Kyoto University) for helpful dis-
.040 mmol) was added. The solution turned light orange cussions on DFT calculations.
3
0
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Paper
Dalton Transactions
1
2 K. O. Christea, D. A. Dixonc, D. McLemorec,
W. W. Wilsonb, J. A. Sheehyb and J. A. Boatz, J. Fluorine
Chem., 2000, 101, 151.
Notes and references
1
J. Dugal-Tessier, E. D. Conrad, G. R. Dake and D. P. Gates,
in Phosphorus(III) Ligands in Homogeneous Catalysis: Design 13 G. C. Fortman, A. M. Z. Slawin and S. P. Nolan, Organome-
and Synthesis, ed. P. C. J. Kamer and P. W. N. M. van
Leeuwen, Wiley, Chichester, UK, 2012, ch. 10.
tallics, 2010, 29, 3966; M. P. Coles and P. B. Hitchcock, Poly-
hedron, 2001, 20, 3027.
2
3
F. Ozawa and M. Yoshifuji, Dalton Trans., 2006, 4987.
For recent examples, see: Y.-H. Chang, Y. Nakajima,
H. Tanaka, K. Yoshizawa and F. Ozawa, J. Am. Chem. Soc.,
14 I. C. Tornieporth-Oetting, T. M. Klapötke, T. S. Cameron,
J. Valkonen, P. Rademacher and K. J. Kowski, J. Chem. Soc.,
Dalton Trans., 1992, 537; D. Mootz and K. Bartmann,
Angew. Chem., Int. Ed. Engl., 1988, 27, 391.
2
013, 135, 11791; Y. Nakajima, Y. Okamoto, Y.-H. Chang
and F. Ozawa, Organometallics, 2013, 32, 2918; Y.-H. Chang, 15 M. Ma, A. Stasch and C. Jones, Chem. – Eur. J., 2012, 18,
Y. Nakajima, M. Tanaka, K. Yoshizawa and F. Ozawa,
Organometallics, 2014, 33, 715; K. Takeuchi, A. Minami,
Y. Nakajima and F. Ozawa, Organometallics, 2014, 33, 5365.
For related studies using phosphaalkene ligands, see:
A. Jouaiti, M. Geoffroy and G. Bernardinelli, Tetrahedron
Lett., 1992, 33, 5071; A. S. Ionkin and W. J. Marshall,
10669; H. Nakazawa, K. Kamata and M. Itazaki, Chem.
Commun., 2005, 4004; M. F. C. Guedes da Silva,
M. A. N. D. A. Lemos, J. J. R. F. da Silva,
A. J. L. Pombeiro, M. A. Pellinghelli and A. Tiripicchio,
J. Chem. Soc., Dalton Trans., 2000, 373; J. S. Thayer,
Inorg. Chem., 1968, 12, 2599.
4
Heteroat. Chem., 2002, 13, 662; S. Ito, M. Nanko and 16 R. Walsh, in The Chemistry of Organic Silicon Compounds,
K. Mikami, ChemCatChem, 2014, 6, 2292.
Y. Nakajima, Y. Nakao, S. Sakaki, Y. Tamada, T. Ono and
ed. S. Patai and Z. Rappoport, Wiley, Chichester, UK, 1989,
ch. 5.
5
6
F. Ozawa, J. Am. Chem. Soc., 2010, 132, 9934; Y. Nakajima 17 G. M. Sheldrick, SHELXS-97, University of Göttingen,
and F. Ozawa, Organometallics, 2012, 31, 2009. Germany, 1997.
Y.-F. Lin, Y. Nakajima and F. Ozawa, Dalton Trans., 2014, 18 G. M. Sheldrick, SHELXL-97, University of Göttingen,
4
3, 9032; Y.-F. Lin, N. Ichihara, Y. Nakajima and F. Ozawa,
Germany, 1997.
Organometallics, 2014, 33, 6700.
Y. Nakajima, Y. Shiraishi, T. Tsuchimoto and F. Ozawa,
Chem. Commun., 2011, 47, 6332.
19 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng,
J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J. A. Montgomery Jr., J. E. Peralta,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers,
K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi,
J. Normand, K. Raghavachari, A. Rendell, J. C. Burant,
S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam,
M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo,
J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev,
A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski,
R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth,
P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels,
O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski and
D. J. Fox, Gaussian 09, Revision C.01, Gaussian, Inc.,
Wallingford, CT, 2010.
7
8
9
J. I. van der Vlugt, E. A. Pidko, D. Vogt, M. Lutz, A. L. Spek
and A. Meetsma, Inorg. Chem., 2008, 47, 4442.
J. Emsley, The Elements, Oxford, New York, 3rd edn, 1998.
0 A. Hayashi, M. Okazaki, F. Ozawa and R. Tanaka, Organo-
metallics, 2007, 26, 5246; C. Müller, E. A. Pidko, M. Lutz,
A. L. Spek and D. Vogt, Chem. – Eur. J., 2008, 14, 8803;
J. I. van der Vlugt, E. A. Pidko, D. Vogt, M. Lutz and
A. L. Spek, Inorg. Chem., 2009, 48, 7513; J. I. van der Vlugt,
E. A. Pidko, R. C. Bauer, Y. Gloaguen, M. K. Rong and
M. Lutz, Chem. – Eur. J., 2011, 17, 3850.
1
1
1 Y. L. Xiao, Q.-H. Jin, Y.-H. Deng, Z.-F. Li, W. Yang,
M.-H. Wu and C.-L. Zhang, Inorg. Chem. Commun., 2012,
1
5, 146; D. Saravanabharathi, Monika, P. Venugopalan and
A. G. Samuelson, Polyhedron, 2002, 21, 2433; J. Ellermann,
F. A. Knoch, K. J. Meier and M. Moll, J. Organomet. Chem.,
1
992, 428, C44.
Dalton Trans.
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