Synthesis and Photophysical Properties of Phenyleneethynylenes Containing a Combination of Two Main Group Element Moieties of B, Si, or P on the Side Chain

Article abstract of DOI:10.1021/acs.organomet.7b00768

X-shaped 1,4-phenyleneethynylenes containing a combination of two main group element moieties of B, Si, or P as part of the side chain have been synthesized. The halogen-lithium exchange of 2-bromo-5-dimethylphenylsilyl-1,4-bis(phenylethynyl)benzene followed by addition of fluorodimesitylborane or chlorodiphenylphosphine gave the X-shaped B/Si and Si/P, respectively. The P-containing molecule was oxidized to afford a P(=O) derivative. The B/PO moieties were introduced to the 1,4-phenyleneethynylene unit by 3 steps, i.e., the halogen-lithium exchange of 2,5-dibromo-1,4-bis(trimethylsilylethynyl)benzene followed by sequential addition of fluorodimesitylborane and chlorodiphenylphosphine oxide, desilylation, and the Sonogashira coupling with aryl iodides. Then, the reduction of the B/PO gave X-shaped B/P derivative. The absorption and fluorescence spectra of the X-shaped molecules showed the molecules have two-dimensional conjugation systems, i.e., the π-conjugation of the original π-conjugation backbone and p(B)π-π? conjugation of B, σ?-π? conjugation of Si, and n-π and σ?-π? conjugation of P, extended from the π-core. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy levels are significantly altered because of a lowering of the LUMO level due to p-π? conjugation for B and σ?-π? conjugation for Si and P compared with the parent phenyleneethynylene, which are also supported by density functional theory calculations.

Full text of DOI:10.1021/acs.organomet.7b00768

Article
Cite This: Organometallics XXXX, XXX, XXX−XXX
Synthesis and Photophysical Properties of Phenyleneethynylenes
Containing a Combination of Two Main Group Element Moieties of B,
Si, or P on the Side Chain
Takanobu Sanji,* Akemi Fuchigami, and Masato Tanaka
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
S
* Supporting Information
ABSTRACT: X-shaped 1,4-phenyleneethynylenes containing a combination of two main group
element moieties of B, Si, or P as part of the side chain have been synthesized. The halogen−
lithium exchange of 2-bromo-5-dimethylphenylsilyl-1,4-bis(phenylethynyl)benzene followed
by addition of fluorodimesitylborane or chlorodiphenylphosphine gave the “X-shaped” B/Si
and Si/P, respectively. The P-containing molecule was oxidized to afford a P(O) derivative.
The B/PO moieties were introduced to the 1,4-phenyleneethynylene unit by 3 steps, i.e., the
halogen−lithium exchange of 2,5-dibromo-1,4-bis(trimethylsilylethynyl)benzene followed by
sequential addition of fluorodimesitylborane and chlorodiphenylphosphine oxide, desilylation,
and the Sonogashira coupling with aryl iodides. Then, the reduction of the B/PO gave
“X-shaped” B/P derivative. The absorption and fluorescence spectra of the “X-shaped” mole-
cules showed the molecules have two-dimensional conjugation systems, i.e., the π-conjugation
of the original π-conjugation backbone and p(B)π−π* conjugation of B, σ*−π* conjugation
of Si, and n−π and σ*−π* conjugation of P, extended from the π-core. The highest occupied
molecular orbital (HOMO)−lowest unoccupied molecular orbital (LUMO) energy levels
are significantly altered because of a lowering of the LUMO level due to p−π* conjugation for B and σ*−π* conjugation for Si
and P compared with the parent phenyleneethynylene, which are also supported by density functional theory calculations.
Chart 1. Chemical Structures of 1,4-Pehenyleneethylenes
Containing a Combination of Main Group Element Moieties
of B, Si, or P as Part of the Side Chain
INTRODUCTION
■
Over the past decades, the design and synthesis of π-conjugated
polymers and oligomers have been active areas of research
because of their applications as optoelectronic materials, such as
organic field-effect transistors and organic electroluminescent
devices. In this regard, main group element-containing π-conju-
gated molecules are interesting.1 When some types of main
group elements, especially those in the group 13, B, 14, Si, and
15, P, are incorporated into the π-conjugated framework, the
orbital interactions, p−π* conjugation for B, σ−π and σ*−π*
conjugation for Si, and n−π conjugation for P, lead to a reduc-
tion in the highest occupied molecular orbital (HOMO)−
lowest unoccupied molecular orbital (LUMO) gaps compared
with the parent π-system. In addition, chemical modifications
such as the oxidation of P can also change the electronic state.
This strategy has been employed to control the electro- and
optical properties, for example, the absorption or emission wave-
lengths, and improved the fluorescence quantum yield, as well
as the solubility of the polymers. Along this line, some examples
of B, Si, and P contained in π-conjugated systems including the
main chain type2,3 and side group type4−6 have been reported.7
In addition, incorporation of two main group elements into
π-conjugated molecules is also reported.8−10
The HOMO−LUMO energy levels are altered due to a rise of
the HOMO level Y(P) or a lowering of the LUMO level (Y(B)
and Y(PO)) compared with the parent phenyleneethynylene,
which is also supported by molecular orbital calculations. At the
same time, the design and synthesis of X-shaped 1,4-phenyl-
eneethynylenes have been extensively studied.12,13 In X-shaped
1,4-phenyleneethynylenes, depending upon their substituents,
We also reported the synthesis and optical properties of
a series of phenyleneethynylenes containing a main group ele-
ment moiety of B, Si, or P on the side chain, which could be
a simple model of the B, Si, and P contained in π-conju-
gated systems (Y(B), Y(Si), Y(P), and Y(PO), Chart 1).11
Received: October 15, 2017
© XXXX American Chemical Society
A
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the frontier molecular orbitals are either congruent, i.e., HOMO
and LUMO occupy the same real space, or disjointed, i.e., the
HOMO is located on one branch of them while the LUMO is
located on the second one. Then, we decided to synthesize
X-shaped 1,4-phenyleneethynylenes containing a combination
of two main group element moieties of B, Si, or P as part of the
side chain, because exploiting a combination of two main group
element groups could be interesting.
Scheme 2. Synthesis of X(B/PO)a−d and X(B/P)a
Here, we show the design, synthesis, and optical properties of
a series of “X-shaped” phenyleneethynylenes containing two
main group element moieties with combinations of B/Si, B/P,
and Si/P on the side chain (Chart 1). The “X-shaped” mole-
cules have two-dimensional conjugation systems, i.e., one is the
original π-conjugation backbone and the other is the p−π*
conjugation of B, σ*−π* conjugation of Si and P, or n−π
conjugation of P, extended from the π-core. These conjugated
molecules with two main group elements across the periodic
table could be an alternative example for conjugated systems.
butyllithium followed by sequential addition of fluorodimesityl-
borane and chlorodiphenylphosphine oxide gave 4. After desily-
lation, the Sonogashira coupling of 5 with aryl iodides gave
X(B/PO). Using this coupling method, X(B/PO)a−e with a
wide variety of aromatic end groups including 4-trifluorophenyl,
4-anisyl-, 2-thienyl, and 4-(N′,N′-diphenylamino)phenyl were
synthesized. Because the B/PO groups as part of the side chain
on the 1,4-phenyleneethynylene could act as an electron-with-
drawing group (vide infra), the electron-donating groups, anisyl,
thienyl, and diphenyaminophenyl groups, were introduced to
X(B/PO) among others. Furthermore, X(B/P)a was obtained
by the reaction of X(B/PO)a with trichlorosilane in good yield.
All compounds were fully characterized (also see the Supporting
Information).
RESULTS AND DISCUSSION
Synthesis. The synthesis of “X-shaped” B/Si, Si/P, and Si/PO
is shown in Scheme 1. In this study, the 1,4-phenyleneethynylene
■
Scheme 1. Synthesis of X(B/Si), X(Si/P), and X(Si/PO)
Optical Properties. The optical properties of “X-shaped”
B/Si, B/P, B/PO, Si/P, and Si/PO are of interest. The optical
data in solution, along with those of a parent compound, 2,5-bis-
(phenylethynyl)benzene (BPEB), are summarized in Table 1.
The absorption and fluorescence spectra of X(B/Si) and also
BPEB are shown in Figure 1. The spectral features of X(B/Si)
are much different from those of BPEB. In the absorption
spectra of X(B/Si), an absorption maximum at 323 nm with an
absorption shoulder at 360 nm is found. The absorption shoulder
is assigned to a cross-conjugated state with orbital contributions
from the empty p-orbital on B along the phenyleneethynylene
framework. When excited at the absorption edge, X(B/Si)
displays a broad emission at around 489 nm with a large Stokes
shift (7330 cm−1 in CH2Cl2). In hexane, a broad emission is
blue-shifted by 30 nm relative to that in CH2Cl2. This band is
assignable to the intramolecular charge transfer emission, where
the dimesitylboryl group could act as a π-acceptor. A peak at
370 nm is found in the excitation spectrum (Figure S1).
Next, the absorption and fluorescence spectra of X(Si/P)
and X(Si/PO) in dichloromethane are shown in Figure 2.
In the absorption of X(Si/P) are found an absorption maximum
at 335 nm and a weak additional absorption band at around
410 nm (ε = 300 cm−1 M−1) assignable to the n−π* transition.
The absorption at around 400 nm is dependent on the solvent
polarity and clearly observed in methanol (Figure S2). When
excited at the n−π* transition, X(Si/P) exhibits a broad emis-
sion at around 509 nm. The excitation spectrum monitored at
this emission shows a peak at 400 nm, which is in good agree-
ment with the n−π* transition in the absorption. It is noted
that a structured emission was found at 390 nm when excited at
310 nm. In contrast, X(Si/PO) displays an absorption maxi-
mum at 345 nm, which is red-shifted by 25 nm relative to that
unit is selected as the parent π-conjugated framework. The reac-
tion of 1,4-dibromo-2,5-bis(phenylethynyl)benzene 1 and butyl-
lithium followed by addition of chlorodimethylphenylsilane gave 2.
The second lithiation followed by addition of fluorodimesityl-
borane (mesityl = 2,4,6-trimethylphenyl) or chlorodiphenylphos-
phine gave the “X-shaped” B/Si or Si/P, respectively. The P-con-
taining molecule, X(Si/P), was oxidized with hydrogen peroxide
to afford X(Si/PO).
The next example is X-shaped conjugated molecules with
B and P, where B is electro-deficient and shows Lewis acid
nature but P is electron-rich and shows Lewis basic nature.
This combination could be interesting. Scheme 2 shows the
synthesis of “X-shaped” B/PO and B/P. The synthesis route
is slightly different from the mentioned above. The reaction
of 1,4-dibromo-2,5-bis(trimethylsilylethynyl)benzene (3) and
B
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Table 1. Optical Data for X(B/Si), X(B/PO), X(B/P), X(Si/P), X(Si/PO), and Model Compounds
a
a
absorption
fluorescence
b
c
d
d
e
compound
λabs (nm)
323
ε (cm−1 M−1
)
λFL (nm)
ΦFL
Stokes shift (cm−1
7330
)
HOMO (eV)
LUMO (eV)
Eg (eV)
51000
X(B/Si)
489
0.01
−5.33
−5.39
−1.95
−2.07
3.38
3.32
360
16000
X(B/PO)a
362
15000
527
520
521
537
0.01
8650
8700
6850
7350
5570
9300, 4100
4740
2100
7890
2030
4690
1770
2800
b
358
23000
0.01
c
384
21000
0.06
d
385
15000
0.01
e
440
34000
583
0.65
f
g
X(B/P)a
X(Si/P)
X(Si/PO)
327, 430 (sh)
335, 410
345
36000, 3000
45000, 300
39000
470, 523
509
0.01, 0.01
0.34
−5.31
−5.35
−5.41
−5.37
−5.41
−5.37
−5.46
−5.43
−1.94
−1.73
−1.85
−1.91
−1.72
−1.73
−1.83
−1.74
3.37
3.62
3.56
3.46
3.69
3.64
3.63
3.69
372, 390
476
0.81
e
Y(B)
305, 345
326
30000, 17000
34700
0.08
e
Y(Si)
354, 371
500
0.29
e
Y(P)
325, 405 (sh)
342
28000, 300
34000
0.13
e
Y(PO)
383, 405
356
0.05
BPEB
320
60300
0.64
c
a
b
d
In CH2Cl2. Excited at the longest absorption maximum wavelengths. Quantum yield determined with quinine sulfate as a standard. Calculated
HOMO−LUMO energy levels at the B3LYP/6-31G* level. From ref 11. Excited at 350 nm. Excited at 430 nm
e
f
g
Figure 3 shows the absorption and fluorescence spectra of X(B/
PO)a−e. The controlled samples for 1,4-pehenyleneethylenes
Figure 1. Absorption and fluorescence spectra of X(B/Si) in hexane
and dichloromethane and BPEB in hexane.
Figure 3. (a) Absorption and (b) fluorescence spectra of X(B/PO)a−e
in dichloromethane.
Figure 2. Absorption and fluorescence spectra of X(Si/P) and
X(Si/PO) in dichloromethane.
with electron-donating groups as the side chain could also
be referred.15 In the absorption, the phenyl-substituted com-
pound, X(B/PO)a, displays two absorption bands at 322 and
362 nm. The longer absorption band observed at 362 nm is
primary ascribed to the cross-conjugated state with orbital
contributions from the empty p-orbital on B with attached
π-systems. When substituted with the electron-withdrawing
of BPEB because of the strong electron-withdrawing P(O)
moiety.14 In the fluorescence spectrum, X(Si/PO) shows a
structured emission at 390 nm. Noted that the absorption and
fluorescence spectra in dichloromethane and THF were not
nearly solvent dependent (Figure S3).
C
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trifluoromethylphenyl group, X(B/PO)b shows an absorption
that is almost the same as that of X(B/PO)a. However, when
substituted with electron-donating groups, anisyl, thienyl, and
diphenyaminophenyl groups, X(B/PO)c−e show red-shifted
absorptions compared to that observed for X(B/PO)a. In the
fluorescence spectra, X(B/PO)a−d show emissions at around
550 nm. X(B/PO)e with the strong electron-donating group
shows an emission at around 600 nm. Furthermore, the fluores-
cence is strongly dependent on the solvent used. For example,
Figure 4 shows the solvent-dependent fluorescence spectra of
Note that introducing B most often provided significant
reducing the quantum yields (∼0.01). Further study of the
detail photophysical process are required.
The conformal films of X(B/Si), X(B/PO), X(B/P), X(Si/P),
and X(Si/PO) on a quartz plate were obtained by casting a
toluene solution and explored the optical properties in the solid
state (Table S1 and Figures S4 and S5). It is noted that in the
fluorescence spectrum the emission of the film of X(B/Si) is
blue-shifted by 43 nm relative to that observed in solution.
X(Si/PO) displays an emission at 399 and 417 nm with a red-
shift of 27 nm relative to that in solution, but X(Si/P) shows an
emission at around 513 nm likewise in solution. The emissions
of the film of X(B/PO)a−e are blue-shifted by 50 nm relative
to that observed in solution. However, the absorption of the
film of X(B/P)a is almost the same as that observed in solution.
Unfortunately, the measurement of the quantum yields in the
solid state, whose information are important for further applica-
tion of the present materials, are not available in our laboratory
at this time.
Density Functional Theory (DFT) Calculations. For
further understanding of the electronic structures, DFT calcula-
tions were performed at the B3LYP/6-31G* level. The mole-
cular orbital (MO) diagrams are shown in Figure 6 and the cal-
culated HOMO and LUMO energy levels are also listed in
Table 1.
Figure 4. Solvent-dependent fluorescence spectra of X(B/PO)e.
The HOMO energy levels of the five compounds, X(B/Si),
X(B/P), X(B/PO), X(Si/P), and X(Si/PO), are almost similar
and distribute on the phenyleneethynylene unit mostly and are
slightly raised relative to that of BPEB (−5.43 eV). When sub-
stituted with phosphorus on the phenyleneethynylene unit, i.e.,
in X(B/P) and X(Si/P), the n orbital of the phosphorus center
slightly contributes to the HOMO.
X(B/PO)e. With increasing the solvent polarity, from hexane
and dichloromethane to methanol, the fluorescence shifts to the
longer wavelengths, and the color of the solution under UV
irradiation is changed from blue to dark orange as shown in the
inset in Figure 4. Thus, the absorption and emission of X(B/PO)
has a charge-transfer character.
However, the effects of substituent are significant on the
LUMO energies. For example, in X(B/Si), the LUMO energy
level is lowered because of p(B)π−π* conjugation and also
σ*(Si−C)−π* conjugation (−1.74 eV for BPEB). The LUMO
energy level of X(B/P) is stabilized p(B)π−π* and σ*(P−C)−π*
orbital interactions. When substituted with large electron-
withdrawing PO group, the LUMO energy level of X(B/PO)
is even more lowered probably because of the increase in the
interactions between the p(B)π or σ*(P−C) orbitals and adjust
π-orbital of the phenyleneethynylene unit. In addition, the
LUMO energy level of X(Si/PO) is still lowered, attributable
to enhancement of the interactions between the σ*(Si−C and
P−C) and adjust π orbitals of the core.
Figure 5 shows the absorption, fluorescence, and excitation
spectra of X(B/P)a. In the absorption spectrum, X(B/P)a
Time-dependent (TD)−DFT calculation data are summarized
in Table 2. The TD−DFT calculation of X(B/Si) suggests
the absorption band is assignable to the intramolecular charge
transfer transition from the HOMO delocalized over the phenyl-
eneethynylene unit to the LUMO and LUMO+1 of the signifi-
cant contribution of the B moiety. The calculated transition
energy (2.95 eV, 421 nm) is similar to the observed value
(∼410 nm). In X(B/P), the absorption originates from the
HOMO partially localized on P to LUMO transition along with
the HOMO to the LUMO+1 of the important contribution of
the B moiety. The absorption of X(B/PO) is associated with
the transition from the HOMO to the LUMO and LUMO+1,
where the calculated HOMO−LUMO energy gap is 2.89 eV
(429 nm). Then, these transitions could involve the intra-
molecular charge transfer nature. Alternatively, the TD−DFT
calculation on X(Si/P) indicates that the absorption originates
from the HOMO partially localized on the P to LUMO transi-
tion along with the HOMO−1 localized on the P to the LUMO.
Figure 5. Absorption, fluorescence, and excitation spectra of X(B/P)a.
displays an absorption maximum at 327 nm along with an
absorption shoulder at around 420 nm, which are associated
with the transitions largely arising from the p−π* conjugation
with B and the n−π conjugation with P extended from the
π-core, respectively. In the fluorescence spectra, when excited at
430 nm, this emission at 523 nm is observed. The excitation
spectra monitored at this emission shows a peak at around
400 nm, which matches the n−π* transition in the absorp-
tion. In contrast, when excited at 350 nm, an emission at
470 nm is observed, and the excitation spectra monitored at
this emission shows a peak at around 370 nm as observed in the
absorption.
D
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Figure 6. MO diagrams of X(B/Si), X(B/PO)a, X(B/P)a, X(Si/P), and X(Si/PO) (B3LYP/6-31G*).
Table 2. Selected Excitation Energies of X(B/Si), X(Si/P), X(Si/PO), and Model Compounds Assigned by TD−DFT
Calculations (B3LYP/6-31G*//B3LYP/6-31G*)
a
compound
energy (eV)
λcalc (nm)
f
transition
HOMO → LUMO (0.67768)
HOMO → LUMO+1 (−0.1711)
HOMO−1 → LUMO (0.68855)
2.95
421
0.3561
X(B/Si)
3.31
2.89
2.94
3.31
375
429
422
375
0.0668
0.3571
0.3404
1.0285
HOMO−1 → LUMO+1 (−0.11397)
HOMO → LUMO (0.68274)
HOMO → LUMO+1 (−0.1711)
HOMO → LUMO (0.68274)
HOMO → LUMO+1 (−0.1711)
HOMO → LUMO (0.67812)
HOMO−1 → LUMO (0.16923)
HOMO → LUMO (0.66946)
HOMO−1 → LUMO (−0.17652)
HOMO → LUMO (0.69959)
X(B/PO)a
X(B/P)a
X(Si/P)
3.52
3.28
353
378
0.3713
1.3232
X(Si/PO)
a
Oscillator strength.
The calculated HOMO−LUMO energy gaps are 3.62 eV for
X(Si/P) and 3.56 eV for X(Si/PO), which are similar to the
observed absorption (335 nm (3.70 eV) for X(Si/P) and 345 nm
(3.59 eV) for X(Si/PO)).
the dimesitylboryl group especially stabilize the LUMO by 0.23,
0.22, and 0.35 eV, respectively (E(LUMO) = −1.72 eV for Y(Si)),
where the vacant p orbital of the B center apparently contributes.
The diphenylphosphinyl group slightly raises the HOMO energy
levels in X(Si/P) and X(B/P) owing to the n−π interaction.
In addition, the LUMOs of X(B/Si), X(Si/P), and X(Si/PO)
show the marginally orbital interactions of the silyl group.
Thus, the “X-shaped” conjugation path is clearly observed for
the LUMOs of the B/Si, B/P, B/PO, and Si/P derivatives and
the HOMO−1 of the Si/P derivative according to DFT calcula-
tions although the role of the silyl group appears to be limited
in comparison to the other substituents.
As mentioned above, we have reported the synthesis and
optical properties of a series of “Y-shaped” phenyleneethynylenes
containing a main group element moiety of B, Si, or P on the
side chain, which could be a model of the “X-shaped” Si/B, Si/P,
and Si/PO (Chart 1).11 The optical properties are listed for
references in Table 1. The absorption and emission maxima
of X-shaped molecules are a red-shifted (5−15 nm) compared
with that of Y(B), Y(P), and Y(PO), along with high molar
absorptivity. The calculated HOMO−LUMO energy gaps of
X(B/Si), X(B/PO), X(B/P), X(Si/P), and X(Si/PO) are nar-
rower than those of the Y-shaped molecules. For example,
when compared to the electronic states of Y(Si), the substi-
tution effects of the B and P moieties on the HOMO and
LUMO are significant. In X(B/Si), X(B/P), and X(B/PO),
CONCLUSIONS
■
We have demonstrated the design and synthesis of “X-shaped”
B/Si/P conjugated molecules. The electronic states could be
controlled by incorporation of B, Si, P, and P(O) groups
compared with the parent π-system, owing to a rise of the
E
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2-bromo-5-dimethylphenylsilyl-1,4-bis(phenylethynyl)benzene (2)
(0.89 g, 1.82 mmol) in THF (5 mL) at −78 °C. After stirring at
−78 °C for 1 h, chlorodiphenylphosphine (0.39 mL, 2.18 mmol) was
added to the mixture at −78 °C. The reaction mixture was allowed to
warm to room temperature and stirred for 26 h. The volatiles were
removed under reduced pressure; then, toluene (20 mL) was added to
the residue. After filtration and removal of the solvent, the residue was
chromatographed on silica gel (hexane/dichloromethane = 5/1, Rf =
0.47) to give X(Si/P) (0.75 g, 1.32 mmol, 72% yield). Yellow powder.
HOMO level (P) or a lowering of the LUMO level (B and
PO), which are also supported by the DFT calculations.
We believe these results have furnished an alternative example
of main group element-containing π-conjugated molecules to
control optical properties. A variety of the structural designs,
for example, side- and end-group-type “X-shaped” conjugation
systems and the combination of the main group elements and
aromatic groups and also further chemical modifications of
B and P moieties could be possible. Further study along this
line is in progress.
1
Mp = 123.5−125.9 °C. H NMR (CDCl3, 300 MHz) δ 0.67 (s, 6H,
3
SiMe), 6.97 (d, JP−H = 3.9 Hz, 1H, C6HH), 7.10−7.23 (m, 8H, Ar),
7.31−7.39 (m, 15H, Ar), 7.53−7.57 (m, 2H, o-CH (SiAr)), 7.64
4
(d, JP−H = 3.9 Hz, 1H, C6HH). 13C NMR (CDCl3, 75 MHz) δ −2.1
EXPERIMENTAL SECTION
3
■
(SiMe), 88.8 (d, JP−C = 6.9 Hz, ethynyl), 90.9 (ethynyl), 94.4
(ethynyl), 98.1 (ethynyl), 122.8, 122.9, 126.5 (d, 2JP−C = 26.3 Hz, P(o-C)),
Measurements. 1H, 11B, 13C, 19F, and 29Si NMR spectra were
recorded using a Bruker DPX 300 FT-NMR spectrometer at 300, 96.3,
75.4, 282, and 60 MHz, respectively. 11B and 31P NMR spectra
were recorded on a Bruker AVANCE 400 spectrometer at 128 and
162 MHz, respectively. 1H and 13C chemical shifts (ppm) were
referenced to solvent residues. 11B, 19F, 29Si, and 31P NMR chemical
shifts (ppm) were referenced to external BF3·Et2O, CFCl3, Me4Si, and
85% H3PO4 (aqueous), respectively. GC−MS were obtained using a
Shimadzu GC−MS 17A/QP-5000 mass spectrometer. High-resolution
and fast atom bombardment (FAB, matrix: 3-nitrobenzyl alcohol)
mass spectra were obtained with a JEOL JMS-700 mass spectrometer
at an ionization potential of 70 eV. Melting points were measured on a
micromelting point apparatus (As-one IA9100). UV−vis spectra were
recorded using an Agilent 8453 spectrometer. Fluorescence spectra
were recorded using a Hitachi F 4500 spectrometer. Fluorescence
quantum yield was determined with quinine sulfate as a standard.
Elemental analysis was performed at the Center for Advanced
Materials Analysis, Technical Department, Tokyo Tech.
3
127.8, 128.1 (d, JP−C = 8.7 Hz, P(m-C)), 128.4, 128.5, 128.6, 128.7,
2
129.0, 129.1, 131.3 (d, JP−C = 17.7 Hz, P(o-C)), 134.1, 134.3, 134.5,
3
135.6, 135.8 (d, JP−C = 6.3 Hz, P(m-C)), 137.4, 138.8, 140.3, 142.0
1
(d, JP−C = 14.6 Hz, P(ipso-C)), several peaks overlapped. 31P{1H}
NMR (CDCl3, 162 MHz) δ −7.8. 29Si{1H} NMR (CDCl3, 60 MHz)
δ −4.7. HR−MS (FAB, matrix = 3-nitrobenzyl alcohol) calcd for
C42H33PSi ([M]+) m/z 596.2089, found 596.2089. Elemental analysis
calculated (%) for C42H33PSi: C, 84.53; H, 5.57. Found: C, 84.25; H,
5.59.
Synthesis of X(Si/PO). A mixture of X(Si/P) (510 mg, 0.85 mmol)
and 30% H2O2 (0.08 mL, 0.93 mmol) in dichloromethane (30 mL)
was stirred at room temperature for 2.5 h. The reaction mixture was
washed with water (30 mL × 2), saturated NH4Cl (aqueous) (40 mL),
and saturated NaCl (aqueous) (30 mL); the organic layer was dried
over anhydrous MgSO4. After filtration and removal of the solvent, the
residue was chromatographed on silica gel (hexane/ethyl acetate =
2/1, Rf = 0.23) to give X(Si/PO) (280 mg, 0.45 mmol, 53% yield).
Yellow powder. Mp = 197.1−198.0 °C. 1H NMR (CDCl3, 300 MHz)
δ 0.70 (s, 6H, SiMe), 6.96−6.99 (m, 2H, p-CH (Ar)), 7.16−7.58 (m,
Materials. All manipulations involving air- and moisture-sensitive
compounds were carried out under an atmosphere of dry nitrogen gas.
All solvents and reagents were of reagent quality, purchased from
commercial sources and used without further purification, unless
otherwise noted below. Toluene, diethyl ether, and THF were dried
and distilled from sodium/benzophenone just before use. Fluoro-
dimesitylborane,16 2,5-dibromo-1,4-bis(phenylethynyl)benzene (1),17
2-bromo-5-dimethylphenylsilyl-1,4-bis(phenylethynyl)benzene (2),11
and 2-bromo-5-dimesitylboryl-1,4-bis(trimethisilylethynyl)benzene (3)18
were prepared using literature procedures.
3
19H, Ar), 7.68 (d, JP−H = 4.2 Hz, 1H, C6HH), 7.78−7.85 (m, 4H,
o-CH (Ar)), 8.11 (d, 4JP−H = 12.9 Hz, 1H, C6HH). 13C NMR (CDCl3,
3
75 MHz) δ −2.3 (SiMe), 88.9 (d, JP−C = 5.2 Hz, ethynyl), 90.2
(ethynyl), 95.6 (ethynyl), 98.7 (ethynyl), 122.3, 122.7, 124.3, 127.9,
3
128.0, 128.3, 128.5, 128.6, 128.8 (d, JP−C = 12.2 Hz, P(m-C)), 129.3,
4
3
131.2, 131.9 (d, JP−C = 2.8 Hz, P(p-C)), 132.2 (d, JP−C = 10.1 Hz,
1
P(m-C)), 132.6, 134.3, 134.6 (d, JP−C = 99.2 Hz, P(ipso-C)), 136.7,
2
2
137.4 (d, JP−C = 9.0 Hz, P(o-C)), 140.5 (d, JP−C = 8.8 Hz, P(o-C)),
144.6 (d, JP−C = 2.1 Hz, P(p-C)), several peaks overlapped. 31P{1H}
4
Synthesis of X(B/Si). A solution of 1.67 M n-butyllithium in hexane
(1.05 mL, 1.75 mmol) was added to a solution of 2-bromo-5-dimethyl-
phenylsilyl-1,4-bis(phenylethynyl)benzene (2) (0.71 g, 1.46 mmol) in
THF (5 mL) at −78 °C. After stirring at −78 °C for 1 h, fluorodimesityl-
borane (0.51 g, 1.90 mmol) in THF (2.5 mL) was added to the
mixture at −78 °C. The reaction mixture was allowed to warm to
room temperature and stirred for 28 h. After addition of water, the
product was extracted with ether (30 mL), and the organic layer was
washed with saturated NH4Cl (aqueous) and saturated NaCl
(aqueous), and dried over anhydrous Na2SO4. After filtration and
removal of the solvent, the residue was chromatographed on silica gel
(hexane/dichloromethane = 5/1, Rf = 0.7) to give X(B/Si) (0.55 g,
0.83 mmol, 57% yield). Pale yellow powder. Mp = 144.5−145.2 °C.
1H NMR (CDCl3, 300 MHz) δ 0.68 (s, 6H, SiMe), 2.01 (s, 12H,
o-Me × 4), 2.24 (s, 6H, p-Me × 2), 6.74 (s, 4H, m-CH (Mes)), 6.97−
7.00 (m, 2H, p-CH (Ar)), 7.17−7.21 (m, 4H, m-CH (Ar)), 7.31−7.34
(m, 5H, o,m-CH (Ar) + p-CH (SiAr)), 7.44 (s, 1H, C6HH), 7.52−7.56
(m, 4H, o-CH (Ar)), 7.62 (s, 1H, C6HH). 13C NMR (CDCl3, 75 MHz)
δ −2.0 (SiMe), 21.2 (o-Me × 4), 23.3 (p-Me × 2), 90.1 (ethynyl), 91.3
(ethynyl), 93.0 (ethynyl), 94.0 (ethynyl), 123.0, 123.2, 125.7, 127.8,
127.9, 128.0, 128.2, 128.3, 128.4, 129.1, 131.2, 131.57, 131.63, 134.3,
137.4, 137.6, 139.2, 139.4, 140.9, 142.2, several peaks overlapped.
11B{1H} NMR (CDCl3, 128 MHz) δ 73.9. 29Si{1H} NMR (CDCl3,
60 MHz) δ −7.2. HR−MS (FAB, matrix = 3-nitrobenzyl alcohol) calcd
for C48H45BSi ([M]+) m/z 660.3384, found 660.3387. Elemental analysis
calculated (%) for C48H45BSi: C, 87.25; H, 6.86. Found: C, 86.90; H, 6.90.
Synthesis of X(Si/P). A solution of 1.67 M n-butyllithium
in hexane (1.31 mL, 2.19 mmol) was added to a solution of
NMR (CDCl3, 162 MHz) δ 28.0. 29Si{1H} NMR (CDCl3, 60 MHz)
δ −6.2. HR−MS (FAB, matrix = 3-nitrobenzyl alcohol) calcd for
C42H33OPSi ([M]+) m/z 612.2038, found 612.2031. Elemental analysis
calculated (%) for C42H33OPSi: C, 82.32; H, 5.43. Found: C, 76.22;
H, 4.00. Low carbon and hydrogen values were obtained even after
multiple analysis attempts using different batches of samples, suggest-
ing incomplete combustion occurs with this compound. Although these
results are outside the range viewed as establishing analytical purity, they
are provided to illustrate the best values obtained to date.
Synthesis of 2-Dimesitylboryl-5-diphenylphosphoryl-1,4-
bis(trimethisilylethynyl)benzene (4). To a solution of 2,5-
dibromo-1,4-bis(trimethylsilylethynyl)benzene (3) (4.04 g, 9.42 mmol)
in ether (80 mL) was added a solution of 1.65 M n-butyllithium
in hexane (6.8 mL, 11.3 mmol) in ether (100 mL) at −78 °C.
After stirring for 1 h, fluorodimesitylborane (3.04 g, 11.3 mmol) was
added to the mixture at −78 °C. The reaction mixture was allowed to
come room temperature and stirred for 6 h. After addition of saturated
NH4Cl (aqueous) (150 mL), the product was extracted with methyl
t-butyl ether, and the organic layer was dried over anhydrous Na2SO4.
After filtration and removal of the solvent, the residue was chromato-
graphed over silica gel (hexane/dichloromethane = 2/1, Rf = 0.73) to
give 2-bromo-5-dimesitylboryl-1,4-bis(trimethisilylethynyl)benzene
(4.82 g, 8.07 mmol, 86% yield). White powder. Mp = 113−115 °C.
1H NMR (CDCl3, 300 MHz) δ −0.04 (s, 9H, SiMe3), 0.23 (s, 9H,
SiMe3), 1.94 (s, 12H, o-Me), 2.26 (s, 12H, p-Me), 6.73 (s, 4H, m-CH),
7.31 (s, 1H, C6H2), 7.69 (s, 1H, C6H2). 13C NMR (CDCl3, 75 MHz)
δ −0.5 (SiMe3), −0.2 (SiMe3), 21.3 (o-Me), 23.3 (p-Me), 100.9 (ethynyl),
F
DOI: 10.1021/acs.organomet.7b00768
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
101.5 (ethynyl), 102.8 (ethynyl), 103.0 (ethynyl), 124.7, 127.7, 127.9,
128.3, 136.9, 137.8, 139.5, 140.9. 11B{1H} NMR (CDCl3, 128 MHz)
δ 72.3. 29Si{1H} NMR (CDCl3, 60 MHz) δ −17.7, −16.6. The physical
and spectral characteristics of the obtained are identical with those
described in the literature.18
solvent, the residue was chromatographed over silica gel (ethyl acetate,
Rf = 0.77) to give X(B/PO)a (320 mg, 0.45 mmol, 89% yield). Yellow
1
powder. Mp = 262.3−263.5 °C. H NMR (CDCl3, 300 MHz) δ 2.03
(s, 12H, o-Me), 2.25 (s, 6H, p-Me), 6.77 (s, 4H, m-CH (Mes)),
6.96−7.20 (m, 10H, Ph), 7.40−7.54 (m, 7H, C6HH + m,p-CH (Ar)),
3
Next, to a solution of 2-bromo-5-dimesitylboryl-1,4-bis-
(trimethisilylethynyl)benzene (6.41 g, 10.7 mmol) in THF (80 mL)
was added a solution of 1.55 M t-butyllithium in pentane (13.8 mL,
21.4 mmol) at −78 °C. After stirring for 1.5 h at the temperature,
diphenylphosphoryl chloride (5.06 g, 21.4 mmol) in THF (20 mL)
was added to the mixture at −78 °C. The reaction mixture was allowed
to come to room temperature and stirred for 22 h. After addition of
H2O (10 mL), the product was extracted with ether (50 mL), and the
organic layer was washed with saturated NaHCO3 (aqueous) (30 mL)
and saturated NaCl (aqueous) (10 mL). The combined organic layer
was dried over anhydrous Na2SO4. After filtration and removal of the
solvent, the residue was chromatographed over silica gel (hexane/ethyl
acetate = 2/1, Rf = 0.27) to give 4 (6.44 g, 8.96 mmol, 84% yield).
7.76−7.82 (m, 4H, o-CH (Ar)), 7.90 (d, JP−H = 13.2 Hz, C6HH).
13C NMR (CDCl3, 75 MHz) δ 21.2 (p-Me), 23.3 (o-Me), 88.7 (d,
3JP−C = 5.6 Hz, ethynyl), 89.0 (ethynyl), 95.3 (ethynyl), 98.6 (ethynyl),
4
3
122.3, 122.7, 125.0 (d, JP−C = 6.2 Hz, P(p-C)), 126.2 (d, JP−C
=
12.6 Hz, P(m-C)), 127.8, 128.0, 128.2, 128.3, 128.5, 128.6, 131.3,
131.5, 131.85 (d, 4JP−C = 2.3 Hz, P(p-C)), 131.91 (d, 1JP−C = 105.8 Hz,
3
1
P(ipso-C)), 132.0 (d, JP−C = 10.0 Hz, P(m-C)), 135.2 (d, JP−C
99.2 Hz, P(ipso-C)), 137.7 (d, 2JP−C = 9.7 Hz, P(o-C)), 138.4 (d, 2JP−C
=
=
8.7 Hz, P(o-C)), 139.6, 140.9. 31P{1H} NMR (CDCl3, 162 MHz)
δ 28.5. 11B{1H} NMR (CDCl3, 128 MHz) δ 72.3. HRMS (FAB,
matrix = 3-nitrobenzyl alcohol) calcd for C52H45BOP (11B, [M + H]+)
m/z 727.3261, found 727.3253. Elemental analysis calculated (%) for
C52H44BOP: C, 85.95; H, 6.10. Found: C, 84.48; H, 6.13. Although
these results are outside the range viewed as establishing analytical
purity, they are provided to illustrate the best values obtained to date.
The NMR spectra are provided in the Supporting Information as
alternative characterization data.
1
White powder. Mp = 237.5−239.8 °C. H NMR (CDCl3, 300 MHz)
δ −0.09 (s, 9H, SiMe), −0.08 (s, 9H, SiMe), 1.96 (s, 12H), 2.26 (s,
6H), 6.74 (s, 6H), 7.42−7.46 (m, 5H, Ar + C6HH), 7.50−7.55 (m,
4
2H, Ar), 7.69−7.76 (m, 4H, Ar), 7.85 (d, JP−H = 13.2 Hz, 1H,
C6HH). 13C NMR (CDCl3, 75 MHz) δ −0.7 (SiMe), −0.5 (SiMe),
Synthesis of X(B/PO)b. A mixture of 5 (230 mg, 0.48 mmol),
4-trifluoroiodobenzene (0.3 mL, 2.10 mmol), Pd(PPh3)4 (56 mg,
0.049 mmol), and CuI (56 mg, 0.29 mmol) in THF/i-Pr2EtN (v. 3/1,
5 mL) was stirred at room temperature for 10 min and then at 50 °C
for 24 h. After addition of dichloromethane (20 mL) and saturated
NH4Cl (aqueous) (20 mL), the aqueous layer was washed with
dichloromethane (5 mL × 2). The combine organic layer was dried
over anhydrous Na2SO4. After filtration and removal of the solvent, the
residue was chromatographed over silica gel (ethyl acetate, Rf = 0.90)
to give X(B/PO)b (280 mg, 0.33 mmol, 69% yield). White powder.
3
21.3 (Me), 23.4 (Me), 101.2 (ethynyl), 103.3 (d, JP−C = 5.3 Hz,
2
ethynyl), 103.5 (ethynyl), 104.7 (ethynyl), 124.8 (d, JP−C = 6.0 Hz,
3
P(o-C)), 126.2 (d, JP−C = 12.0 Hz, P(m-C)), 128.3, 128.4, 131.8, (d,
4JP−C = 3.0 Hz, P(p-C)), 132.0 (d, 1JP−C = 106.5 Hz, P(ipso-C)), 132.2
3
1
(d, JP−C = 9.8 Hz, P(m-C)), 135.2 (d, JP−C = 99.0 Hz, P(ipso-C)),
2
4
138.4 (d, JP−C = 5.3 Hz, P(o-C)), 138.5 (d, JP−C = 3.8 Hz, P(o-C)),
139.7, 141.0, several peaks overlapped. 31P{1H} NMR (CDCl3, 162 MHz)
δ 28.2. 11B{1H} NMR (CDCl3, 128 MHz) δ 72.8. 29Si{1H} NMR
(CDCl3, 60 MHz) δ −17.8, −17.3. HRMS (FAB, matrix = 3-nitroben-
zyl alcohol) calcd for C46H53BOPSi2 (11B. [M + H]+) m/z 719.3465,
found 719.3464. Elemental analysis calculated (%) for C46H52BOPSi2:
C, 76.86; H, 7.29. Found: C, 75.43; H, 7.06. Although these results are
outside the range viewed as establishing analytical purity, they are
provided to illustrate the best values obtained to date.
1
Mp = 211.8−213.9 °C. H NMR (CDCl3, 300 MHz) δ 2.01 (s, 12H,
o-Me), 2.25 (s, 6H, p-Me), 6.77 (s, 4H, m-CH (Mes)), 7.03−7.34 (m,
6H, o,m-CH (p-CF3C6H4)), 7.43−7.53 (m, 9H, C6HH + m,p-CH (Ar) +
m-CH (p-CF3C6H4)), 7.57 (d, 3JP−H = 4.2 Hz, C6HH), 7.72−7.80 (m,
4H, o-CH (Ar)). 13C{1H} NMR (CDCl3, 75 MHz) δ 21.2
(p-Me), 23.4 (o-Me), 90.6 (d, 3JP−C = 5.4 Hz, ethynyl), 91.0 (ethynyl),
Synthesis of 2-Dimesitylboryl-5-diphenylphosphoryl-1,4-
bis(ethynyl)benzene (5). A solution of 1 M TBAF in THF
(60 mL, 60 mmol) was added to 4 (2.03 g, 2.82 mmol) at room
temperature, and the mixture was stirred for 3 h. After addition of H2O
(60 mL) and dichloromethane (20 mL), the aqueous layer was washed
with dichloromethane (10 mL × 2). The combined organic layer was
dried over Na2SO4. After filtration and removal of the solvent, the
residue was chromatographed over silica gel (ethyl acetate, Rf = 0.77)
to give 5 (0.73 g, 1.28 mmol, 85% yield). Pale yellow powder. Mp =
189.4−190.5 °C. 1H NMR (CDCl3, 300 MHz) δ 1.96 (s, 12H, o-Me),
2.24 (s, 6H, p-Me), 2.78 (s, 1H, ethynyl), 3.01 (s, 1H, ethynyl), 6.73
(s, 4H, m−CH(Mes)), 7.41−7.53 (m, 7H, m,p−CH(Ar) + C6HH),7.58
3
93.9 (ethynyl), 97.2 (ethynyl), 124.8 (quart, JF−C = 3.7 Hz,
3
p-CF3C6H4), 125.0 (quart, JF−C = 4.1 Hz, p-CF3C6H4), 125.6 (d,
3
4JP−C = 3.8 Hz, P(p-C)), 125.9 (d, JP−C = 12.4 Hz, P(m-C)), 127.2
1
(quart, JF−C = 259.5 Hz, p-CF3C6H4), 128.5, 128.6, 128.7, 129.8
(quart, 2JF−C = 30.3 Hz, p-CF3C6H4), 130.0, 131.60, 131.61 (d, 1JP−C
=
106.3 Hz, P(ipso-C)), 131.8, 132.0 (d, 3JP−C = 9.4 Hz, P(m-C)), 132.1
4
1
(d, JP−C = 2.8 Hz, P(p-C)), 135.8 (d, JP−C = 98.8 Hz, P(ipso-C)),
137.8 (d, 2JP−C = 10.1 Hz, P(o-C)), 138.7 (d, 2JP−C = 8.4 Hz, P(o-C)),
139.9, 141.0, several peaks overlapped. 19F NMR (CDCl3, 282 MHz)
δ −62.8, −62.8. 11B{1H} NMR (CDCl3, 128 MHz) δ 75.1. 31P{1H}
NMR (CDCl3, 162 MHz) δ 28.8. HRMS (FAB, matrix = 3-nitrobenzyl
alcohol) calcd for C54H43BF6OP (11B, [M + H]+) m/z 863.3049,
found 863.3054. Elemental analysis calculated (%) for C54H42BF6OP:
C, 75.18; H, 4.91. Found: C, 71.58; H, 4.85. Although these results are
outside the range viewed as establishing analytical purity, they are
provided to illustrate the best values obtained to date. The NMR
spectra are provided in the Supporting Information as alternative
characterization data.
3
(d, JP−H = 13.2 Hz, 2H), 7.65−7.72 (m, 4H, o−CH(Ph)). 13C NMR
4
(CDCl3, 75 MHz) δ 21.2 (p-Me), 23.2 (o-Me), 81.4 (d, JP−C
=
5.8 Hz, ethynyl), 81.8 (ethynyl), 83.1 (ethynyl), 86.5 (ethynyl), 124.5
4
3
(d, JP−C = 5.8 Hz, P(p-C)), 125.4 (d, JP−C = 12.6 Hz, P(m-C)),
1
128.2, 128.3, 128.5, 131.6 (d, JP−C = 98.6 Hz, P(ipso-C)), 137.7 (d,
2JP−C = 10.1 Hz, P(o-C)), 139.2 (d, JP−C = 8.6 Hz, P(o-C)), 139.8,
2
140.9, several peaks overlapped. 31P{1H} NMR (CDCl3, 162 MHz)
δ 28.7. 11B{1H} NMR (CDCl3, 128 MHz) δ 72.3. HRMS (FAB,
matrix = 3-nitrobenzyl alcohol) calcd for C40H37BOP (11B, [M + H]+)
m/z 575.2675, found 575.2682. Elemental analysis calculated (%) for
C40H36BOP: C, 83.63; H, 6.32. Found: C, 81.91; H, 6.42. Satisfactory
elemental analysis data could not be obtained. The NMR spectra are
provided in the Supporting Information as alternative characterization
data.
Synthesis of X(B/PO)c. A mixture of 5 (290 mg, 0.50 mmol),
4-iodoanisole (490 mg, 2.11 mmol), Pd(PPh3)4 (58 mg, 0.050 mmol),
and CuI (55 mg, 0.29 mmol) in THF/i-Pr2EtN (v. 3/1, 5 mL) was
stirred at room temperature for 10 min and then at 50 °C for 22 h.
After addition of dichloromethane (30 mL) and saturated NH4Cl
(aqueous) (30 mL), the aqueous layer was washed with dichloro-
methane (5 mL × 2). The combine organic layer was dried over
anhydrous Na2SO4. After filtration and removal of the solvent, the
residue was chromatographed over silica gel (ethyl acetate, Rf = 0.57)
to give X(B/PO)c (280 mg, 0.36 mmol, 71% yield). Yellow powder.
Synthesis of X(B/PO)a. A mixture of 5 (290 mg, 0.50 mmol),
iodobenzene (0.25 mL, 2.24 mmol), Pd(PPh3)4 (60 mg, 0.052 mmol),
and CuI (55 mg, 0.29 mmol) in THF/i-Pr2EtN (v. 3/1, 5 mL) was
stirred at 50 °C for 15 h. After addition of dichloromethane (30 mL)
and saturated NH4Cl (aqueous) (30 mL), the aqueous layer was
washed with dichloromethane (5 mL × 2). The combine organic layer
was dried over anhydrous Na2SO4. After filtration and removal of the
1
Mp = 189.4−190.5 °C. H NMR (CDCl3, 300 MHz) δ 2.01 (s, 12H,
o-Me × 4), 2.25 (s, 6H, p-Me × 2), 3.75 (s, 3H, OMe), 3.76 (s, 3H,
OMe), 6.68−6.71 (m, 4H, m-CH (p-An)), 6.76 (s, 4H, m-CH (Mes)),
6.89−6.98 (m, 4H, o-CH (An)), 7.38−7.52 (m, 7H, C6HH + m,p-CH
G
DOI: 10.1021/acs.organomet.7b00768
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Organometallics
Article
(Ph)), 7.73−7.82 (m, 4H, o-CH (Ar)), 7.84(d, 3JP−H = 13.2 Hz, C6HH).
147.1, 147.8, 148.1, several peaks overlapped. 11B{1H} NMR (CDCl3,
128 MHz) δ 78.5. 31P{1H} NMR (CDCl3, 162 MHz) δ 28.7.
HRMS (FAB, matrix = 3-nitrobenzyl alcohol/NaCl) calcd for
C76H62BN2OPNa (11B, [M + Na]+) m/z 1083.4590, found 1083.4637.
Satisfactory elemental analysis data could not be obtained. The NMR
spectra are provided in the Supporting Information as alternative
characterization data.
13C NMR (CDCl3, 75 MHz) δ 21.2 (p-Me), 23.3 (o-Me), 55.2(0)
3
(OMe), 55.2(3) (OMe), 87.8 (d, JP−C = 5.5 Hz, ethynyl), 88.0
(ethynyl), 95.4 (ethynyl), 98.8 (ethynyl), 113.5 (m-C (p-An)), 113.6
(m-C (p-An)), 114.5 (ipso-C (p-An)), 115.0 (ipso-C (p-An)), 125.5 (d,
4
4JP−C = 6.6 Hz, P(p-C)), 128.3, 128.5, 131.8 (d, JP−C = 2.6 Hz,
1
3
P(p-C)), 132.07 (d, JP−C = 105.8 Hz, P(ipso-C)), 132.09 (d, JP−C
=
Synthesis of X(B/P)a. A toluene-d8 solution (0.30 mL) of X(B/P)a
(44.2 mg, 0.061 mmol) and trichlorosilane (0.03 mL, 0.297 mmol)
was heated at 100 °C for 23 h. After evaporation, to the residue was
added chloroform-d (0.50 mL), and the soluble part was subjected to
the NMR measurement. After evaporation under reduced pressure,
X(B/P)a was obtained (25.9 mg, 0.036 mmol, 60% yield). Yellow
9.9 Hz, P(m-C)), 132.9 (o-C (p-An)), 133.1 (o-C (p-An)), 134.9 (d,
2
1JP−C = 99.5 Hz, P(ipso-C)), 137.6 (d, JP−C = 9.8 Hz, P(o-C)), 138.2
2
(d, JP−C = 9.1 Hz, P(o-C)), 139.5, 140.9, 159.5 (p-C (p-An)), 159.8
(p-C(p-An)), several peaks overlapped. 11B{1H} NMR (CDCl3,
128 MHz) δ 74.6. 31P{1H} NMR (CDCl3, 162 MHz) δ 28.7.
HRMS (FAB, matrix = 3-nitrobenzyl alcohol) calcd for C54H49BO3P
(11B, [M + H]+) m/z 787.3512, found 787.3515. Elemental analysis
calculated (%) for C54H48BO3P: C, 82.44; H, 6.15. Found: C, 82.11;
H, 6.44.
1
powder. Mp = 192.8−195.6 °C. H NMR (CDCl3, 300 MHz) δ 2.08
(s, 12H, o-Me), 2.27 (s, 6H, p-Me), 6.78 (s, 4H, m-CH (Mes)),
6.92−6.95 (m, 2H, p-CH (Ph)), 7.06 (d, 3JP−H = 4.5 Hz, 1H, C6HH),
7.16−7.37 (m, 17H, C6HH + Ph), 7.61−7.73 (m, 2H). 13C NMR
(CDCl3, 75 MHz) δ 21.2 (p-Me), 23.3 (o-Me), 90.1 (ethynyl), 93.3
(ethynyl), 123.2, 125.9, 126.7, 127.0, 127.7, 128.4, 128.5, 128.7, 128.8,
129.1, 130.88 (d, 2JP−C = 26.9 Hz, P(o-C)), 130.93 (d, 2JP−C = 25.4 Hz,
P(o-C)), 131.5, 134.0, 134.3, 135.3 (d, 3JP−C = 8.3 Hz, P(m-C)), 137.2
Synthesis of X(B/PO)d. A mixture of 5 (270 mg, 0.47 mmol),
2-iodothiophene (0.20 mL, 2.0 mmol), Pd(PPh3)4 (59 mg, 0.051 mmol),
and CuI (54 mg, 0.28 mmol) in THF/i-Pr2EtN (v. 3/1, 5 mL) was
stirred at room temperature for 10 min and then at 50 °C for 21 h.
After addition of dichloromethane (20 mL) and saturated NH4Cl
(aqueous) (20 mL), the aqueous layer was washed with dichloro-
methane (5 mL × 2). The combine organic layer was dried over
anhydrous Na2SO4. After filtration and removal of the solvent, the
residue was chromatographed over silica gel (ethyl acetate, Rf = 0.63)
to give X(B/PO)d (270 mg, 0.36 mmol, 76% yield). Yellow powder.
3
1
(d, JP−C = 6.4 Hz, P(m-C)), 138.0 (d, JP−C = 14.4 Hz, P(ipso-C)),
1
139.1, 140.7 (d, JP−C = 20.3 Hz, P(ipso-C)), 140.9, 142.6, several
peaks overlapped. 11B{1H} NMR (CDCl3, 128 MHz) δ 72.3. 31P{1H}
NMR (CDCl3, 162 MHz) δ −12.78. HRMS (FAB, matrix = 3-nitro-
benzyl alcohol) calcd for C52H45BP (11B, [M + H]+) m/z 712.3430,
found 712.3388. Satisfactory elemental analysis data could not be
obtained. The NMR spectra are provided in the Supporting Information
as alternative characterization data.
1
Mp = 265.9−267.5 °C. H NMR (CDCl3, 300 MHz) δ 2.02 (s, 12H,
o-Me), 2.25 (s, 6H, p-Me), 6.78 (s, 4H, m-CH (Mes)), 6.83−6.88 (m,
4H, 4,5-CH (thienyl)), 7.18 (dd, JH−H = 4.7 and 1.2 Hz, 1H, 3-CH
(thienyl)), 7.20 (dd, JH−H = 4.5, 1.2 Hz, 1H, 3-CH (thienyl)), 7.40−
7.54 (m, 7H, C6HH + m,p-CH (Ar)), 7.74−7.81 (m, 4H, o-CH (Ar)),
DFT and TD−DFT Calculations. The geometries and electronic
structures of the molecules were calculated using DFT with B3LYP/
6-31G*//B3LYP/6-31G* as the basis set of the Gaussian program.19
3
7.95 (d, JP−H = 13.2 Hz, 1H, C6HH). 13C{1H} NMR (CDCl3,
75 MHz) δ 21.3 (m-Me), 23.3 (p-Me), 88.8 (ethynyl), 92.1 (ethynyl),
3
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the ACS
Publications website at DOI: 10.1021/acs.organomet.7b00768.
92.4 (d, JP−C = 5.4 Hz, ethynyl), 92.7 (ethynyl), 122.2, 122.8, 124.4
■
4
3
(d, JP−C = 6.3 Hz, P(p-C)), 126.1 (d, JP−C = 12.5 Hz, P(m-C)),
S
1
126.8, 126.9, 127.8, 128.2, 128.4, 128.6, 131.7 (d, JP−C = 106.1 Hz,
P(ipso-C)), 131.9 (d, JP−C = 2.8 Hz, P(p-C)), 132.1 (d, JP−C
4
3
=
10.1 Hz, P(m-C)), 132.5, 135.1 (d, 1JP−C = 98.7 Hz, P(ipso-C)), 137.5
(d, 2JP−C = 9.5 Hz, P(o-C)), 138.1 (d, 2JP−C = 8.6 Hz, P(o-C)), 139.7,
140.8, several peaks overlapped. 11B{1H} NMR (CDCl3, 128 MHz)
δ 72.6. 31P{1H} NMR (CDCl3, 162 MHz) δ 28.2. HRMS (FAB,
matrix = 3-nitrobenzyl alcohol) calcd for C48H41BOPS2 (11B, [M +
H]+) m/z 740.2508, found 740.2477. Elemental analysis calculated
(%) for C48H40BOPS2: C, 78.04; H, 5.46. Found: C, 77.14; H, 5.47.
Although these results are outside the range viewed as establishing
analytical purity, they are provided to illustrate the best values
obtained to date. The NMR spectra are provided in the Supporting
Information as alternative characterization data.
Detail of photophysical properties and NMR spectra for
all new compounds(PDF)
Computed Cartesian coordinates of X(B/Si), X(B/PO)a,
X(B/P)a, X(Si/P), and X(Si/PO) (XYZ)
AUTHOR INFORMATION
Corresponding Author
*E-mail: takanobu.sanji@jst.go.jp.
ORCID
Takanobu Sanji: 0000-0003-1211-8279
Notes
The authors declare no competing financial interest.
■
Synthesis of X(B/PO)e. A mixture of 5 (290 mg, 0.50 mmol),
4-iodotriphenylamine (730 mg, 2.0 mmol), Pd(PPh3)4 (58 mg,
0.050 mmol), and CuI (48 mg, 0.25 mmol) in THF/i-Pr2EtN (v. 3/1,
6 mL) was stirred at room temperature for 10 min and then at 50 °C
for 26 h. After addition of dichloromethane (20 mL) and saturated
NH4Cl (aqueous) (30 mL), the aqueous layer was washed with
dichloromethane (10 mL × 4). The combined organic layer was dried
over anhydrous Na2SO4. After filtration and removal of the solvent, the
residue was chromatographed over silica gel (ethyl acetate, Rf = 0.83)
to give X(B/PO)e (440 mg, 0.42 mmol, 83% yield). Pale yellow
ACKNOWLEDGMENTS
This work was supported by Grants-in-Aids from JSPS
KAKENHI, No. 24550042 and 15H03813.
■
1
powder. Mp = 264.9−266.5 °C. H NMR (CDCl3, 300 MHz) δ 2.04
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I
DOI: 10.1021/acs.organomet.7b00768
Organometallics XXXX, XXX, XXX−XXX