N-P bond cleavage induced ring formation of cyclosilazanes from reactions of aryl(phosphanyl)aminotrichlorosilanes with lithium alkynyls

Article abstract of DOI:10.1021/om401095n

The aryl(silyl)aminotrichlorosilane 2,6-iPr₂C₆H ₃N(SiMe₂Ph)SiCl₃ (1) and aryl(phosphanyl) aminotrichlorosilane ArN(PPh₂)SiCl₃ (Ar = 2,6-iPr ₂C₆H₃

Full text of DOI:10.1021/om401095n

Article
pubs.acs.org/Organometallics
N−P Bond Cleavage Induced Ring Formation of Cyclosilazanes from
Reactions of Aryl(phosphanyl)aminotrichlorosilanes with Lithium
Alkynyls
Jinjin Wang,† Rui Liu,† Wenqing Ruan,† Yan Li,† Kartik Chandra Mondal,‡ Herbert W. Roesky,‡
and Hongping Zhu*,†
†State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of
Alcohols−Ethers−Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, People’s Republic of
China
‡Institut fur Anorganische Chemie, Georg-August-Universitat, Tammannstraße 4, 37077 Gottingen, Germany
̈
̈
̈
S
* Supporting Information
ABSTRACT: The aryl(silyl)aminotrichlorosilane 2,6-
iPr2C6H3N(SiMe2Ph)SiCl3 (1) and aryl(phosphanyl)-
aminotrichlorosilane ArN(PPh2)SiCl3 (Ar = 2,6-iPr2C6H3
(2), 4-MeC6H4 (3), 2,4,6-Me3C6H2 (4)) were prepared and
utilized for investigation in reactions with freshly prepared
lithium alkynyls. Reaction of 1 with PhCCLi resulted in the
compounds PhMe2SiCCPh and 2,6-iPr2C6H3N[Li(THF)3]-
Si(CCPh)3 (5), while 2 reacted with R′CCLi to produce
the compounds Ph2PCCR′ and [2,6-iPr2C6H3NSi(CCR′)2]2 (R′ = Ph (6), tBu (7), CH2CH2Ph (8)). Reaction of 3 with
PhCCLi led to the formation of Ph2PCCPh and [4-MeC6H4NSi(CCPh)2]3 (9a) as a major product and {4-
MeC6H4NSi(CCPh)[N(4-MeC6H4)Si(CCPh)3]}2 (9b) as a minor product. When 4 was reacted with PhCCLi, [2,4,6-
Me3C6H2NSi(CCPh)2]2 (10a) was isolated as the major product while [(2,4,6-Me3C6H2)3N3Si2(CCPh)4Li(THF)]−[Li-
(THF)4]+ (10b) was the minor product. The formation of Ph2PCCPh was also detected. All reported compounds were
characterized by multinuclear NMR (1H, 13C, 29Si, and/or 31P) and/or IR spectroscopy, and compounds 2, 5−8, 9a, and 10b
were further distinguished by single-crystal X-ray crystallography. These results exhibit a route to the Si2N2- or Si3N3-based
cyclosilazanes 6−8, 9a, 9b, and 10a via the N−P bond cleavage of the aryl(phosphanyl)aminotrichlorosilanes during multiple
metathesis reactions.
synthesis of cyclosilazanes having different ring or cage
structures. However, cyclosilazanes which are tuned at the Si
atom usually require additional metathesis reactions when
silicon halide is utilized as the precursor. There are also reports
on metathesis reactions at the Si atoms of the preformed Si2N2
ring.4j Herein, we report a direct synthetic route to Si-
alkynylated cyclosilazanes by reacting N-silyl and -phosphanyl
group substituted arylaminotrichlorosilanes, ArN(R)SiCl3 (Ar
= 2,6-iPr2C6H3, R = SiMe2Ph (1), PPh2 (2); Ar = 4-MeC6H4, R
= PPh2 (3); Ar = 2,4,6-Me3C6H2, R = PPh2 (4)), as precursors
with several lithium alkynyls. A series of Si2N2 ring compounds
[2,6-iPr2C6H3NSi(CCR′)2]2 (R′ = Ph (6), tBu (7),
CH2CH2Ph (8)) and {4-MeC6H4NSi(CCPh)[N(4-
MeC6H4)Si(CCPh)3]}2 (9b) and the cyclic Si3N3 compound
[4-MeC6H4NSi(CCPh)2]3 (9a) were produced and structur-
ally characterized together with the lithium derivatives 2,6-
iPr2C6H3N[Li(THF)3]Si(CCPh)3 (5) and [(2,4,6-
Me3C6H2)3N3Si2(CCPh)4Li(THF)]−[Li(THF)4]+ (10).
INTRODUCTION
■
Cyclosilazanes are Si- and N-based cyclic compounds and are
often used as single-source precursors for the preparation of
silicon nitride, an important valuable refractory material.1 This
combination constitutes a special class of compounds with rich
Si−N bonds without any carbon atoms in the ring skeletons.2
Cyclosilazanes with alternating silicon and nitrogen centers are
normally prepared by the reaction of primary amines with
dihalosilanes. Alternatively, they are also synthesized by a
number of other routes (Chart 1).2a,3−5 They consist of a
variety of ring or cage structures which largely depend on the
size of the substituents at either the Si or N atom. By taking
advantage of the sterically demanding groups, acyclic types of
R2SiNR′ (R2, R′ = organic substituent(s)) have also been
obtained.6 The latter compound is known as a silaimine, which
contains a SiN double bond with strongly polar character
and thus is prone to undergo cycloaddition reactions. They are
often considered as intermediates which finally resulted in the
preparation of cyclosilazane.5 Nevertheless, the ring formation
via inter- or intramolecular salt elimination leading to
cyclosilazanes has also been suggested.4b,c It is noted that the
various R′-substituted primary amines can be provided for
Received: November 11, 2013
© XXXX American Chemical Society
A
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raphy. The 29Si NMR spectrum of 1 exhibits a resonance at δ
1.83 ppm corresponding to the silicon atom of the SiMe2Ph
group. The resonance at δ −27.1 ppm is assigned to the silicon
atom for the SiCl3 group, which can be compared with those
observed in silyltrichloride Ar′N(SiMe3)SiCl3 (Ar′ = 2,6-
Me2C6H3, δSiCl −28.2 ppm; 2-iPr-6-MeC6H3, δSiCl −27.9
Chart 1. Some Examples of Cyclosilazanes Prepared from
Chlorosilanes
3
3
ppm; 2,4,6-Me3C6H2, δSiCl −28.3 ppm).7 The 29Si NMR
3
spectra of 2−4 display a resonance of the SiCl3 group (δ
−28.90 ppm and JPSi = 24.10 Hz for 2, −26.65 ppm and 48.90
Hz for 3, and −28.61 ppm and 48.90 Hz for 4). These
resonances each split into a doublet due to the coupling with
the 31P nucleus of PPh2. The 31P NMR spectra exhibit each a
resonance at δ 55.69 ppm for 2, 54.73 ppm for 3, and 42.73
ppm for 4, respectively.
Reaction of 1 with freshly prepared PhCCLi8 in a molar
ratio of 1:4 was carried out in a mixture of solvents (Et2O/
THF). The reaction was performed initially at −78 °C, and the
temperature was slowly raised to room temperature. The
compound 2,6-iPr2C6H3N[Li(THF)3]Si(CCPh)3 (5) was
isolated as the major product. The formation of PhMe2SiC
CPh9 as a side product was also detected, which was concluded
by NMR (1H and 13C) and IR spectral analysis (Scheme 2).
Scheme 2. Reaction of 1 with PhCCLi To Give
Compound 5 and PhMe2SiCCPh
These results show the formation of a variety of cyclosilazanes
originated by multiple metathesis reactions.
RESULTS AND DISCUSSION
■
The N-silyl or -phosphanyl group bonded arylaminotrichlor-
osilanes ArN(R)SiCl3 (Ar = 2,6-iPr2C6H3, R = SiMe2Ph (1),
PPh2 (2); Ar = 4-MeC6H4, R = PPh2 (3); Ar = 2,4,6-Me3C6H2,
R = PPh2 (4)) were prepared by using a consecutive route. The
monosubstituted aryl amine ArNH(R) was prepared from
ArNH2 in situ with nBuLi and then treated with chlorodime-
thylphenylsilane (PhMe2SiCl) or chlorodiphenylphosphine
(Ph2PCl). The deprotonation of ArNH(R) using nBuLi
resulted in Ar(R)NLi. The latter was further employed for
the reaction with SiCl4. By removal of insoluble LiCl and all
volatiles, washing with cold n-hexane, and crystallization of the
n-hexane washing solution at −20 °C, the target compounds
were obtained as off-white solids together with colorless crystals
in good yield (1, 81%; 2, 89%; 3, 74%; 4, 88%). A general
preparative procedure of these compounds is shown in Scheme
1. Compounds 1−4 were characterized by multinuclear NMR
(1H, 13C, 29Si, and/or 31P) spectroscopy and elemental analysis,
and compound 2 was further confirmed by X-ray crystallog-
Under similar conditions, the reaction of 2 with PhCCLi in a
1:3 molar ratio yielded compound [2,6-iPr2C6H3NSi(C
CPh)2]2 (6) with a Si2N2 four-membered ring. By replacing
PhCCLi with tBuCCLi and PhCH2CH2CCLi, similar
products [2,6-iPr2C6H3NSi(CCtBu)2]2 (7) and [2,6-
iPr2C6H3NSi(CCCH2CH2Ph)2]2 (8) were obtained
(Scheme 3). In the last three reactions, the respective
Scheme 3. Reactions of 2 with R′CCLi To Give
Compounds 6−8 and the Corresponding Ph2PCCR′
Scheme 1. Consecutive Route Synthesis of Compounds 1−4
compound Ph2PCCR′ (R′ = Ph during the formation of 6,
tBu for 7, and CH2CH2Ph for 8) was also produced, as
evidenced by the 31P resonance.10
The formation of 5 indicates the substitution of all chlorine
atoms at the Si atom of 1 by three phenylethynyl groups with
PhCCLi. The compound 2,6-iPr2C6H3N(SiMe2Ph)Si(C
CPh)3 (C) probably forms and further reacts by metathesis
with PhCCLi to give 5 and PhMe2SiCCPh (Scheme 4).
Comparable examples have only been observed for reactions of
B
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Scheme 4. Plausible Formation of Compound 5
R1CCSi(SiMe3)3 (R1 = H, Me, Ph, SiMe3, Si(SiMe3)3) with
KOtBu to give R1CCSi(SiMe3)2K and Me3SiOtBu.11 We
performed the reactions of 1 with PhCCLi in a molar ratio of
1:3 or even 1:2 under the same conditions in an attempt to
isolate C, but failed. Compound 5 and PhMe2SiCCPh were
always formed, although in a relatively low yield. Moreover, the
starting material 1 was found unreacted on the basis of 29Si
NMR measurements. The formation of 6−8 might involve an
initial production of the lithium amide 2,6-iPr2C6H3N(Li)SiCl3
(A) with release of Ph2PCCR′. A reacts with elimination of
LiCl to give B, and B is then transferred to 6−8 through further
metathesis with R′CCLi (Scheme 5). The lithium amide A
can be compared with 5, which is well-known as an
intermediate for the formation of cyclosilazanes.4b,c B has
been isolated as a stable compound by treatment of in situ
formed 2,6-iPr2C6H3N(H)SiCl3 with nBuLi or Et3N (see the
synthesis and characterization in the Supporting Information).
Obviously, the formation of 6−8 is different from that of 5,
probably because the N-bonded group is SiMe2Ph in 1 while in
2 it is the PPh2 substituent.12
Figure 1. X-ray single-crystal structure (50% probability level of the
thermal ellipsoids) of 6 with H atoms omitted for clarity. Selected
bond lengths (Å) and angles (deg) (data in brackets are for another
independent molecule): Si(1)−N(1) 1.724(2) [1.721(2)], Si(2)−
N(1) 1.722(2) [1.719(2)], C(1)−C(2) 1.198(3) [1.201(3)], C(11)−
C(12) 1.199(3) [1.210(3)]; N(1)−Si(1)−N(1A) 86.38(13)
[86.60(12)], Si(1)−N(1)−Si(2) 93.55(10) [93.47(9)], Si(1)−
C(1)−C(2) 174.3(2) [175.1(2)], Si(2)−C(11)−C(12) 173.4(2)
1
[169.8(2)]. Symmetry code: (A) −x, y, −z + /2.
Compounds 5−8 were isolated as colorless crystals in
moderate to good yields (72% for 5, 62% for 6, 55% for 7, and
68% for 8). All reported compounds are moisture sensitive.
Compound 5 is thermally unstable and decomposes at 108 °C.
Compounds 6−8 appear stable up to the melting points of 224,
165, and 198 °C, respectively. They have been fully
characterized by NMR (1H, 13C, and 29Si) and IR spectroscopy,
elemental analysis, and X-ray crystallography.
The crystal structure of 5 is shown in Figure 1s (see the
Supporting Information), which clearly reveals that three
phenylethynyl groups are bound to the Si atom. Moreover,
Li(THF)3 is coordinated to the N atom. NMR and IR
spectroscopy shows the 13C resonances (δ 97.04 and 101.80
ppm) and the corresponding IR band (ν 2152.8 cm−1) for the
phenylethynyl CC functionality. The presence of the
coordinated THF molecules is evidenced from the character-
istic H (δ 1.34 and 3.52 ppm) and 13C (δ 25.30 and 68.05
1
ppm) NMR data. The 29Si NMR spectrum displays the silicon
resonance (δ −93.59 ppm), which is comparable to those
found in alkynylsilanes (RCC)4Si (R = 4-MeC6H4, δ −92.63
ppm; R = 4-tBuC6H4, −92.52 ppm; R = 4-PhC6H4, −92.52
ppm).13
Figure 2. X-ray single-crystal structure (50% probability level of the
thermal ellipsoids) of 7 with H atoms omitted for clarity. Selected
bond lengths (Å) and angles (deg): Si(1)−N(1) 1.706(4), Si(1)−
N(1A) 1.660(3), C(1)−C(2) 1.239(6), C(11)−C(12) 1.249(6);
N(1)−Si(1)−N(1A) 79.06(16), Si(1)−N(1)−Si(2) 100.94(16),
Si(1)−C(1)−C(2) 172.4(5), Si(1)−C(11)−C(12) 171.9(4). Symme-
try code: (A) −x + 2, −y, −z + 1.
The crystal structures of 6−8 are displayed in Figures 1−3
with selected bond distances and angles. All compounds
Scheme 5. Reasonable Reaction Pathway to Compounds 6−8
C
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atom. The Si−N bond lengths (1.719(2)−1.724(2) Å in 6,
1.660(3)−1.706(4) Å in 7, and 1.715(5)−1.725(2) Å in 8) are
comparable to those of the previously reported ring compounds
(1.713(1)−1.756(6) Å)4f,g,i,k but longer than those in 5
(1.640(1) Å) as well as in silaimines having Si−N double
bonds (1.5329(16)−1.6209(13) Å).6d−g The 29Si NMR spectra
exhibit resonances at δ −88.33 for 6, −63.12 for 7, and −61.96
ppm for 8, respectively.
We further carried out the reaction of 3 with 3 equiv of
PhCCLi and the isolated compound [4-MeC6H4NSi(C
CPh)2]3 (9a) as colorless square blocks in 52% yield. To our
surprise, another compound {4-MeC6H4NSi(CCPh)[N(4-
MeC6H4)Si(CCPh)3]}2 (9b) was also obtained as colorless
plates in a very low yield (8%, Scheme 6). Similarly, the
reaction of 4 with 3 equiv of PhCCLi was completed and
compound [2,4,6-Me3C6H2NSi(CCPh)2]2 (10a) was ob-
tained as colorless needles of the major part (66%), while
[(2,4,6-Me3C6H2)3N3Si2(CCPh)4Li(THF)]−[Li(THF)4]+
(10b) was produced as colorless arris-piece crystals as the
minor part (8%, Scheme 7). In both reactions Ph2PCCPh
was formed. The formation of 9a or 10a follows the reaction
pathway similarly to those of 6−8. The production of 9b might
undergo an additional metathesis reaction involving the
intermediate 4-MeC6H4NLi[Si(CCPh)3], like that of com-
pound 5. However, compound 10b could be considered as a
result of the further reaction of 10a with the possibly in situ
formed dilithium amide 2,4,6-Me3C6H2NLi2, a known type
species that can be produced from the reaction of primary
amine with nBuLi.14 Nonetheless, due to the very low yield of
9b and 10b, the detailed mechanism for the formation of these
two compounds still needs further investigation.
Compounds 9a,b and 10a,b are moisture sensitive.
Compound 9a melts at 216 °C, while 9b has a melting point
at 257 °C. Correspondingly, 10a has a clear melting point at
242 °C, whereas 10b decomposes when heated to 178 °C, as
indicated by a color change from colorless to yellow and finally
to black. Compounds 9a and 10b have been confirmed by
NMR and IR spectroscopy and elemental analysis as well as by
single-crystal X-ray structures. Compounds 9b and 10a have
been characterized by NMR and IR spectroscopy and elemental
analysis, and their composition and structure have been further
supported by a preliminary structural analysis from X-ray
diffraction studies.15 The crystal structure of 9a is shown in
Figure 4 and that of 10b in Figure 2s in the Supporting
Information. Compound 9a features a Si3N3 six-membered ring
(ΔSi(1)N(1)Si(2)N(2)Si(3)N(3) = 0.0638 Å), which deviates slightly
from the ideal plane in comparison to those of 6−8. In the
similar compounds (ArNSiMe2)3 (Ar = o-MeC6H4, m-MeC6H4,
Figure 3. X-ray single-crystal structure (50% probability level of the
thermal ellipsoids) of 8 with H atoms omitted for clarity. Selected
bond lengths (Å) and angles (deg) (data in brackets are for another
independent molecule): Si(1)−N(1) 1.718(2) [1.725(2)], Si(1)−
N(1A) 1.715(5) [1.720(2)], C(1)−C(2) 1.194(4) [1.199(4)],
C(11)−C(12) 1.203(4) [1.204(4)]; N(1)−Si(1)−N(1A) 86.68(11)
[86.52(11)], Si(1)−N(1)−Si(1A) 93.32(11) [93.48(11)], Si(1)−
C(1)−C(2) 178.3(3) [175.9(3)], Si(1)−C(11)−C(12) 178.0(3)
[174.9(3)]. Symmetry code: (A) −x, −y + 2, −z.
contain an ideal N2Si2 planar four-membered ring with a centro
symmetry (the Δ values of the least-square planes of
Si(1)N(1)Si(2)N(1A) and Si(3)N(2)Si(4)N(2A) in 6, Si(1)-
N(1)Si(1A)N(1A) in 7, and Si(1)N(1)Si(1A)N(1A) and
Si(2)N(2)Si(2A)N(2A) in 8 are all calculated to be 0.0000
Å). This structural feature appears common in (RNSiMe2)2 (R
= SiMe3, Mes, SiH(SiMe3)2, SiMetBu2),4k and (RNSiCl2)2 (R =
tBu,4h 2,6-iPr2C6H3). Exceptional examples are found in the
nonplanar ring compounds [(tBu2ClSi)NSiCl(NH2)]2,4i
(MesNSiClMes)2,4f and MesNSi(tBu)(X)N(Mes)Si(tBu)-
(NHMes) (X = H, Cl; Mes = 2,4,6-Me3C6H2),4g probably
due to the two different groups attached at the Si atoms of the
ring. In these planes the N-aryls are perpendicularly arranged
while two alkynyl groups are located up and down at each Si
Scheme 6. Reaction of 3 and PhCCLi To Give Compounds 9a,b and Ph2PCCPh
D
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Scheme 7. Reaction of 4 with PhCCLi To Give Compounds 10a,b and Ph2PCCPh
CONCLUSION
■
In summary, we have prepared the aryl(silyl)-
aminotrichlorosilane 2,6-iPr2C6H3N(SiMe2Ph)SiCl3 (1) and
aryl(phosphanyl)aminotrichlorosilane ArN(PPh2)SiCl3 (Ar =
2,6-iPr2C6H3 (2), 4-MeC6H4 (3), 2,4,6-Me3C6H2 (4)) and
carried out the reactions of these compounds with several
lithium alkynyls. The reaction of 1 with PhCCLi underwent
the substitution of all the chlorine atoms at the silicon center
with phenylethynyls and moreover a cleavage of the N−SiSiMe Ph
2
bond, leading to the formation of the compounds 2,6-
iPr2C6H3N[Li(THF)3]Si(CCPh)3 (5) and PhMe2SiC
CPh. The reactions of 2−4 with R′CCLi, however, resulted
in the cleavage of the N−PPPh bond and the substitution of the
2
chlorides with alkynyls, producing the cyclosilazanes [2,6-
iPr2C6H3NSi(CCR′)2]2 (R′ = Ph (6), tBu (7), CH2CH2Ph
(8)), [4-MeC6H4NSi(CCPh)2]3 (9a), {4-MeC6H4NSi(C
CPh)[N(4-MeC6H4)Si(CCPh)3]}2 (9b), and [2,4,6-
Me3C6H2NSi(CCPh)2]2 (10a) and the ionic lithium salt
derivative [(2,4,6-Me3C6H2)3N3Si2(CCPh)4Li(THF)]−[Li-
(THF)4]+ (10b). In all cases Ph2PCCR′ (R′ = Ph in the
reactions of 2−4 with PhCCLi, R = tBu in the reaction of 2
with tBuCCLi, and R = CH2CH2Ph in the reaction of 2 with
PhCH2CH2CCLi) was formed. These results reveal a novel
synthetic route for the formation of cyclosilazanes via the N−
Figure 4. X-ray single-crystal structure (50% probability level of the
thermal ellipsoids) of 9a with H atoms omitted for clarity. Selected
bond lengths (Å) and angles (deg): Si(1)−N(1) 1.717(4), N(1)−
Si(2) 1.724(4), Si(2)−N(2) 1.721(4), N(2)−Si(3) 1.722(4), Si(3)−
N(3) 1.719(3), N(3)−Si(1) 1.724(3), C(1)−C(2) 1.166(8), C(11)−
C(12) 1.231(8), C(21)−C(22) 1.200(7), C(31)−C(32) 1.215(7),
C(41)−C(42) 1.199(7), C(51)−C(52) 1.204(7); N(1)−Si(1)−N(3)
108.98(17), Si(1)−N(3)−Si(3) 130.5(2), N(3)−Si(3)−N(2)
108.86(18), Si(3)−N(2)−Si(2) 128.4(2), N(2)−Si(2)−N(1)
108.91(18), Si(2)−N(1)−Si(1) 130.4(2).
PPPh bond cleavage by multiple metathesis reactions when
2
aryl(phosphanyl)aminotrichlorosilanes were utilized as the
starting material and reacted with the lithium alkynyls.
EXPERIMENTAL SECTION
■
Materials and Methods. All manipulations were carried out
under a dry argon or nitrogen atmosphere by using Schlenk line and
glovebox techniques. The organic solvents toluene, n-hexane, diethyl
ether, and tetrahydrofuran were dried by refluxing with sodium/
potassium benzophenone under N2 prior to use. The NMR (1H, 13C,
29Si, and 31P) spectra were recorded on a Bruker Avance II 400 or 500
MHz spectrometer. Infrared spectra were obtained on a Nicolet FT-IR
330 spectrometer. Melting points of compounds were measured in a
p-MeC6H4) the boatlike Si3N3 ring conformations were
indicated.16 Inside the ring, Si−N bond lengths (1.717(4)−
1.724(4) Å) can be compared to those in the Si2N2 four-
membered rings of 6 and 8, but the N−Si−N (108.86(18)−
108.93(17)°) and Si−N−Si bond angles (128.4(2)−130.5(2)°)
become wider (in 6 and 8, N−Si−N 86.38(13)−88.08(5)° and
Si−N−Si 91.92(5)−93.55(10)°). Compound 10b is an ion pair
with the anionic part of the Si2N3Li-fused six-membered ring
and cationic part of [Li(THF)4]+. The N−Li bond lengths are
1.913(6) and 1.941(6) Å and are shorter in comparison to that
in 5 (2.005(3) Å), probably due to the ring restriction and the
lower coordination around the Li atom. The N(1)−Si(1)
(1.638(3) Å) and N(2)−Si(2) (1.654(3) Å) bond lengths are
remarkably shorter than the N(3)−Si(1) (1.729(2) Å) and
N(3)−Si(2) bond lengths (1.745(2) Å) because of the
coordination of both N(1) and N(2) atoms to the Li. The
first two distances are close to that found in 5, while the last
two are comparable to those of the cyclosilazanes 6, 8, and 9a,
respectively.
sealed glass tube using a Buchi-540 instrument. Elemental analysis was
̈
performed on a Thermo Quest Italia SPA EA 1110 instrument.
Commercial reagents were purchased from Aldrich, Acros, or Alfa-
Aesar Chemical Co. and used as received.
Synthesis of 2,6-iPr2C6H3N(SiMe2Ph)SiCl3 (1). At −78 °C nBuLi
(20.83 mL, 2.4 M solution in n-hexane, 50 mmol) was added dropwise
to a solution of 2,6-iPr2C6H3NH2 (9.43 mL, 50 mmol) in diethyl ether
(150 mL). The mixture was warmed to room temperature and stirred
for 12 h to form the lithium salt 2,6-iPr2C6H3NHLi. This solution was
again cooled to −78 °C, and to it was added neat PhMe2SiCl (8.27
mL, 50 mmol). The mixture was warmed to room temperature and
stirred for 12 h to give 2,6-iPr2C6H3NH(SiMe2Ph), which was directly
used for further reaction without isolation. This suspension was cooled
again to −78 °C, and to it was added nBuLi (20.83 mL, 2.4 M solution
E
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in n-hexane, 50 mmol). After the mixture was warmed to room
temperature over 24 h, the lithium salt 2,6-iPr2C6H3N(SiMe2Ph)Li
was formed, which was cooled to −78 °C and to it was added neat
SiCl4 (5.75 mL, 50 mmol). The mixture reacted by naturally warming
to room temperature. After additional stirring for 12 h, all of the
insoluble solids were filtered off and the filtrate was evaporated to
dryness under reduced pressure. The remaining residue was washed
with cold n-hexane (2 × 5 mL) to give an off-white solid of 1 (15.63
g). The n-hexane washing solution was kept at −20 °C for 2 days to
give a second crop of 1 as colorless crystals (2.39 g). Total yield: 18.02
compound PhMe2SiCCPh was analyzed to be the major component
by NMR (1H and 13C) and IR spectral analysis. The extract was stored
at −20 °C for 2 days to give colorless crystals of 5. Yield: 0.63 g, 72%
1
(based on 1). Mp: 108 °C dec. Data for 5 are as follows. H NMR
(400 MHz, C6D6, 298 K, ppm): δ 1.34 (m, 12 H, THF-OCH2CH2),
3
1.55 (d, 12 H, JHH = 6.8 Hz, CHMe2), 3.52 (m, 12 H, THF-
3
OCH2CH2), 4.61 (sept, 2 H, JHH = 6.8 Hz, CHMe2), 6.91 (m), 7.09
(m), 7.30−7.50 (m) (18 H, C6H3 and Ph). 13C NMR (100 MHz,
C6D6, 298 K, ppm): δ = 25.30 (THF-OCH2CH2), 25.36, 28.00
(CHMe2), 68.05 (THF-OCH2CH2), 97.04, 101.80 (CC), 117.57,
122.71, 124.44, 127.67, 127.89, 132.11, 143.28, 151.26 (C6H3 and Ph).
29Si NMR (99 MHz, C6D6, 298 K, ppm): δ −93.59 (SiCCPh). IR
(KBr plate, cm−1): ν 2152.8 (CC). Data for PhMe2SiCCPh are as
1
g, 81%. Mp: 86 °C. H NMR (400 MHz, C6D6, 298 K, ppm): δ 0.63
(s, 6 H, SiMe2Ph), 1.26 (d, 6 H, 3JHH = 6.8 Hz, CHMe2), 1.39 (d, 6 H,
3
3JHH = 6.8 Hz, CHMe2), 3.63 (sept, 2 H, JHH = 6.8 Hz, CHMe2),
7.14−7.24 (m), 7.32 (m), 7.70 (m) (8 H, C6H3 and Ph). 13C NMR
(100 MHz, C6D6, 298 K, ppm): δ −0.18 (SiMe2Ph), 24.25, 25.45,
28.31 (CHMe2), 124.65, 127.09, 127.88, 130.17, 134.81, 135.67,
138.01, 147.38 (C6H3 and Ph). 29Si NMR (99 MHz, C6D6, 298 K,
ppm): δ −27.06 (SiCl3), 1.83 (SiMe2Ph). Anal. Calcd for
C20H28Cl3NSi2 (Mr = 444.97): C, 53.98; H, 6.34; N, 3.15. Found:
C, 53.90; H, 6.29; N, 3.32.
1
follows. H NMR (400 MHz, C6D6, 298 K, ppm): δ 0.46 (s, 6 H,
SiMe2), 6.80−7.54 (m) (10 H, Ph). 13C NMR (100 MHz, C6D6, 298
K, ppm): δ 2.6 (SiMe2), 92.02, 106.80 (CC), 123.45, 127.62, 127.84,
129.21, 129.34, 132.11, 133.57, 148.22 (Ph). IR (KBr plate, cm−1): ν
2158.6 (CC). Anal. Calcd for C48H56LiNO3Si (5, Mr = 729.99): C,
78.98; H, 7.73; N, 1.92. Found: C, 78.49; H, 7.96; N, 1.86. Note: the
initial reaction was carried out between 1 and 3 equiv of PhCCLi,
and 5 was isolated as colorless crystals as well but in a relatively lower
yield (48%) based on PhCCLi.
Synthesis of ArN(PPh2)SiCl3. The synthetic procedure on the
same scale was similar to that of 1, in which in addition to 2,6-
iPr2C6H3NH2 two other primary arylamines were used (4-
MeC6H4NH2, 5.40 g, 50 mmol; 2,4,6-Me3C6H2NH2, 7.02 mL, 50
mmol), and Ph2PCl (8.27 mL, 50 mmol) was used instead of
PhMe2SiCl.
Synthesis of [2,6-iPr2C6H3NSi(CCPh)2]2 (6). PhCCLi (6
mmol in 50 mL of Et2O) was freshly prepared in a manner similar to
that used in the synthesis of 5 and added to a solution of 2 (0.99 g, 2.0
mmol) in THF (6 mL) at −78 °C. The mixture was warmed to room
temperature and stirred for 12 h. The insoluble solid was removed by
filtration, and the filtrate was evaporated to dryness under reduced
pressure. The residue was washed with n-hexane (8 mL) followed by
extraction with a THF/n-hexane (2 mL/6 mL) mixture. The n-hexane
washing solution was dried to give a viscous oil, of which compound
Ph2PCCPh was analyzed to be the major component by 31P NMR.
The extract was stored at −20 °C for 3 days to afford colorless crystals
2,6-iPr2C6H3N(PPh2)SiCl3 (2). Yield: 22.02 g, 89%. Mp: 99 °C. 1H
3
NMR (400 MHz, C6D6, 298 K, ppm): δ 0.56 (d, 6 H, JHH = 6.8 Hz,
CHMe2), 1.23 (d, 6 H, 3JHH = 6.8 Hz, CHMe2), 3.36 (sept, 2 H, 3JHH
=
C
6.8 Hz, CHMe2), 6.97−7.16 (m), 7.65 (m) (13 H, C6H3 and Ph). 13
NMR (100 MHz, C6D6, 298 K, ppm): δ 23.28, 25.52, 29.35 (CHMe2),
124.96, 128.35 (d, JCP = 8.1 Hz), 130.25, 135.14, 135.34, 135.50 (d, JCP
= 25.1 Hz), 138.64 (d, JCP = 2.8 Hz), 148.04 (C6H3 and Ph). 29Si
NMR (99 MHz, C6D6, 298 K, ppm): δ −28.90 (d, JSiP = 24.1 Hz,
SiCl3). 31P NMR (160 MHz, C6D6, 298 K, ppm): δ 54.73. Anal. Calcd
for C24H27Cl3NPSi (Mr = 494.90): C, 58.25; H, 5.50; N, 2.83. Found:
C, 58.32;H, 5.53; N, 2.85.
1
of 6. Yield: 0.50 g, 62% (based on 2). Mp: 224 °C. H NMR (400
3
MHz, C6D6, 298 K, ppm): δ 1.61 (d, 24 H, JHH = 6.8 Hz, CHMe2),
4.68 (sept, 4 H, 3JHH = 6.8 Hz, CHMe2), 6.86 (m), 7.29 (m), 7.39 (m)
(26 H, C6H3 and Ph). 13C NMR (100 MHz, C6D6, 298 K, ppm): δ
26.63, 28.91 (CHMe2), 91.73, 108.37 (CC), 122.24, 124.34, 125.69,
127.67, 128.19, 129.23, 132.37, 148.21 (C6H3 and Ph). 29Si NMR (99
MHz, C6D6, 298 K, ppm): δ −88.33 (SiCCPh). IR (KBr plate,
cm−1): ν 2154.4 (CC). Anal. Calcd for C56H54N2Si2 (Mr = 811.21):
C, 82.91; H, 6.71; N, 3.45. Found: C, 82.98; H, 6.59; N, 3.47.
Synthesis of [2,6-iPr2C6H3NSi(CCtBu)2]2 (7). The preparation
of 7 is similar to that of 6 on the same scale. tBuCCLi was freshly
prepared by reacting tBuCCH (0.49 g, 6 mmol) with nBuLi (2.5
mL, 2.4 M in n-hexane, 6 mmol) in Et2O (50 mL) from −30 °C to
room temperature within 3 h and was used instead of PhCCLi.
Compound Ph2PCCtBu was characterized by 31P NMR, and 7 was
obtained as colorless crystals. Yield: 0.40 g, 55% (based on 2). Mp:
1
4-MeC6H4N(PPh2)SiCl3 (3). Yield: 15.62 g, 74%. Mp: 141 °C. H
NMR (400 MHz, C6D6, 298 K, ppm): δ 1.87 (s, 3 H, 4-MeC6H4), 6.54
(dd, 2 H, 3JHH = 8.0 Hz, JPH = 2.0 Hz, C6H4), 6.65 (d, 2 H, 3JHH = 8.0
Hz, C6H4), 7.03 (m), 7.44 (m) (10 H, Ph). 13C NMR (100 MHz,
C6D6, 298 K, ppm): δ 20.49 (4-MeC6H4), 128.21 (d, JCP = 6.5 Hz),
129.48 (d, JCP = 21.3 Hz), 129.99, 133.65 (d, JCP = 21.5 Hz), 135.89,
136.06, 136.30, 137.80 (d, JCP = 3.6 Hz) (C6H4 and Ph). 29Si NMR
(99 MHz, C6D6, 298 K, ppm): δ = −26.65 (d, JSiP = 48.9 Hz, SiCl3).
31P NMR (160 MHz, C6D6, 298 K, ppm): δ 55.69. Anal. Calcd for
C19H17Cl3NPSi (Mr = 424.76): C, 53.72; H, 4.03; N, 3.30. Found: C,
53.55; H, 4.01; N, 3.25.
2,4,6-Me3C6H2N(PPh2)SiCl3 (4). Yield: 19.92 g, 88%. Mp: 115 °C.
1H NMR (400 MHz, C6D6, 298 K, ppm): δ 1.71 (s, 6 H, 2,6-
Me2C6H2), 2.05 (s, 3 H, 4-MeC6H2), 6.61 (s, 2 H, C6H2), 6.66−7.07
(m), 7.66 (m) (10 H, Ph). 13C NMR (100 MHz, C6D6, 298 K, ppm):
δ 19.72 (2,6-Me2C6H2), 20.59 (4-MeC6H2), 128.15 (d, JCP = 20.0 Hz),
130.01 (d, JCP = 60.6 Hz), 135.14, 135.29, 135.33 (d, JCP = 26.3 Hz),
136.20, 137.53 (d, JCP = 2.2 Hz), 138.10 (C6H2 and Ph). 29Si NMR
1
165 °C. H NMR (400 MHz, C6D6, 298 K, ppm): δ 1.05 (s, 36 H,
3
3
tBu), 1.58 (d, 24 H, JHH = 6.8 Hz, CHMe2), 4.36 (sept, 4 H, JHH
=
6.8 Hz, CHMe2), 7.20−7.30 (m, 6 H, C6H3). 13C NMR (100 MHz,
C6D6, 298 K, ppm): δ 27.09, 27.79, 28.20, 30.16 (tBu and CHMe2),
81.83, 118.62 (CC), 124.06, 125.23, 134.78, 148.04 (C6H3). 29Si
NMR (99 MHz, C6D6, 298 K, ppm): δ −63.12 (SiCCtBu). IR (KBr
plate, cm−1): ν 2149.4 (CC). Anal. Calcd for C48H70N2Si2 (Mr =
731.25): C, 78.84; H, 9.65; N, 3.83. Found: C, 78.95; H, 9.57; N, 3.70.
Synthesis of [2,6-iPr2C6H3NSi(CCCH2CH2Ph)2]2 (8). The
preparation of 8 is similar to that of 6 on the same scale.
PhCH2 CH2 CCLi was freshly prepared by reacting
PhCH2CH2CCH (0.78 g, 6 mmol) with nBuLi (2.5 mL, 2.4 M in
n-hexane, 6 mmol) in Et2O (50 mL) from −30 °C to room
temperature within 3 h and was used instead of PhCCLi. Finally,
compound Ph2PCCCH2CH2Ph was characterized by 31P NMR, and
8 was obtained as colorless crystals. Yield: 0.63 g, 68% (based on 2).
(99 MHz, C6D6, 298 K, ppm): δ −28.61 (d, JSiP = 44.5 Hz, SiCl3). 31
P
NMR (160 MHz, C6D6, 298 K, ppm): δ 42.73. Anal. Calcd for
C21H21Cl3NPSi (Mr = 452.82): C, 55.70; H, 4.67; N, 3.09. Found: C,
55.67; H, 4.71; N, 3.08.
Synthesis of 2,6-iPr2C6H3N[Li(THF)3]Si(CCPh)3 (5). PhC
CLi was freshly prepared by reacting PhCCH (0.49 g, 4.8 mmol)
and nBuLi (2.0 mL, 2.4 M in n-hexane, 4.8 mmol) in Et2O (50 mL)
from −30 °C to room temperature within 3 h and adding this mixture
to a solution of 1 (0.53 g, 1.2 mmol) in THF (6 mL) at −78 °C. The
mixture reacted on warming to room temperature. After the mixture
was stirred for an additional 12 h, the insoluble solid was removed by
filtration and then the filtrate was evaporated to dryness under reduced
pressure. The remaining residue was washed with n-hexane (10 mL)
followed by extraction with a THF/n-hexane (2 mL/4 mL) mixture.
The n-hexane washing solution was dried to give a viscous oil, of which
1
Mp: 198 °C. H NMR (400 MHz, C6D6, 298 K, ppm): δ 1.52 (d, 24
3
3
H, JHH = 6.8 Hz, CHMe2), 2.30 (t, 8 H, JHH = 8.4 Hz, C
CCH2CH2), 2.63 (t, 24 H, 3JHH = 8.4 Hz, CCCH2CH2), 4.43 (sept,
3
4 H, JHH = 6.8 Hz, CHMe2), 6.92 (m), 6.98−7.08 (m), 7.25−7.33
(m) (26 H, C6H3 and Ph). 13C NMR (100 MHz, C6D6, 298 K, ppm):
F
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δ 22.47, 26.38, 28.43, 34.39 (CHMe2 and CCCH2CH2), 83.41,
109.85 (CC), 124.15, 125.28, 126.35, 128.28, 128.44, 134.40,
140.26, 148.05 (C6H3 and Ph). 29Si NMR (99 MHz, C6D6, 298 K,
ppm): δ −61.96 (SiCCCH2CH2Ph). IR (KBr plate, cm−1): ν 2177.1
(CC). Anal. Calcd for C64H70N2Si2 (Mr = 923.40): C, 83.24; H,
7.64; N, 3.03. Found: C, 83.14; H, 7.74; N, 2.98.
2156.9 (CC). Anal. Calcd for C50H42N2Si2 (Mr = 727.05): C, 82.60;
H, 5.82; N, 3.85. Found: C, 82.55; H, 5.59; N, 3.72. Data for 10b·
toluene are as follows. Mp: 178 °C (dec.). 1H NMR (400 MHz, C6D6,
298 K, ppm): δ 1.33 (m, 20 H, THF-OCH2CH2), 2.11 (s, 3 H, MePh),
2.20 (s, 6 H), 2.21 (s, 3 H), 2.27 (s, 6 H), 2.85 (s, 3 H), 3.14 (s, 3 H),
3.21 (s, 6 H) (2,4,6-Me3C6H2), 3.49 (m, 20 H, THF-OCH2CH2),
6.77−7.49 (m, 26 H, C6H2, CCPh, and MePh). 13C NMR (100
MHz, C6D6, 298 K, ppm): δ 19.20, 20.42, 20.75, 20.84, 22.78, 31.70
(2,4,6-Me3C6H2), 25.33 (THF-OCH2CH2), 67.86 (THF-OCH2CH2),
89.98, 94.72, 101.16, 105.47 (CC), 122.31, 122.79, 123.42, 123.77,
124.49, 128.90, 129.24, 129.80, 129.08, 131.37, 132.01, 132.11, 132.19,
132.85, 133.26, 134.64, 136.17, 137.04, 137.71, 138.61 (C6H2, C
CPh, and MePh). 29Si NMR (99 MHz, C6D6, 298 K, ppm): δ −51.15
(SiCCPh). IR (KBr plate, cm−1): ν 2161.3 (CC). Anal. Calcd for
C86H101Li2N3O5Si2 (10b·toluene, Mr = 1326.79): C, 77.85; H, 7.67; N,
3.17. Found: C, 77.45; H, 7.39; N, 3.12.
Synthesis of [4-MeC6H4NSi(CCPh)2]3 (9a) and {4-
MeC6H4NSi(CCPh)[N(4-MeC6H4)Si(CCPh)3]}2 (9b). PhC
CLi (6 mmol in 50 mL of Et2O) was freshly prepared in a manner
similar to that used in the synthesis of 5 and added to a solution of 3
(0.85 g, 2.0 mmol) in THF (6 mL) at −78 °C. The mixture was
warmed to room temperature and stirred for 12 h. The insoluble solid
was removed by filtration, and the filtrate was evaporated to dryness
under reduced pressure. The residue was washed with n-hexane (8
mL) followed by extraction with a THF/n-hexane (2 mL/6 mL)
solvent mixture. The n-hexane washing solution was dried and
analyzed to contain Ph2PCCPh on the basis of 31P NMR data. The
extract was stored at −20 °C for 3 days to give colorless square-block
crystals of 9a·2THF (0.40 g, 52% yield based on 3). The mother
solution was decanted into another bottle and stored at −20 °C for
another 3 days to afford colorless crystalline plates of 9b·THF (0.058
g, 8% yield based on 3). Data for 9a·2THF are as follows. Mp: 216 °C.
1H NMR (400 MHz, C6D6, 298 K, ppm): δ 1.42 (m, 8 H, THF-
ASSOCIATED CONTENT
* Supporting Information
■
S
Text, tables, and CIF files giving crystal data and structure
refinement details and crystal structures of compounds 2, 5,
and 10b·toluene and the synthesis, characterization, and crystal
structure of (2,6-iPr2C6H3NSiCl2)2 (B). This material is
available free of charge via the Internet at http://pubs.acs.org.
OCH2CH2), 2.07 (s, 9 H, 4-MeC6H4), 3.58 (m, 8 H, THF-
OCH2CH2), 6.79−6.87 (m), 7.27 (m) (30 H, Ph), 7.07 (d, 6 H,
3
3JHH = 6.4 Hz, 4-MeC6H4), 8.13 (d, 6 H, JHH = 6.4 Hz, 4-MeC6H4).
13C NMR (100 MHz, C6D6, 298 K, ppm): δ 25.44 (THF-OCH2CH2),
31.57 (4-MeC6H4), 67.47 (THF-OCH2CH2), 91.06, 106.84 (CC),
122.78, 127.96, 128.51, 129.39, 131.14, 132.24, 134.60, 139.75 (4-
MeC6H4 and Ph). 29Si NMR (99 MHz, C6D6, 298 K, ppm): δ −56.37
(SiCCPh). IR (KBr plate, cm−1): ν = 2158.4 (CC). Anal. Calcd
for C77H67N3O2Si3 (9a·2THF, Mr = 1150.63): C, 80.38; H, 5.87; N,
3.65. Found: C, 80.15; H, 5.96; N, 3.62. Data for 9b·THF are as
follows. Mp: 257 °C. 1H NMR (400 MHz, C6D6, 298 K, ppm): δ 1.42
(m, 4 H, THF-OCH2CH2), 1.87 (s, 6 H, 4-MeC6H4), 2.09 (s, 6 H, 4-
AUTHOR INFORMATION
Corresponding Author
*E-mail for H.Z.: hpzhu@xmu.edu.cn.
Notes
■
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
3
This work was supported by the 973 Program
(2012CB821704), the National Nature Science Foundation of
China (20972129), the Science Foundation of Ministry of
Education of China (2009060011500466), and the Innovative
Research Team Program (IRT1036).
MeC6H4), 3.58 (m, 4 H, THF-OCH2CH2), 6.72 (d, 2 H, JHH = 6.4
3
3
Hz), 6.83 (d, 2 H, JHH = 6.4 Hz), 6.89 (d, 2 H, JHH = 6.4 Hz), 6.98
3
3
(d, 2 H, JHH = 6.4 Hz), 7.30 (d, 2 H, JHH = 6.4 Hz), 7.49 (d, 2 H,
3JHH = 6.4 Hz), 7.74 (d, 2 H, 3JHH = 6.4 Hz), 8.11 (d, 2 H, 3JHH = 6.4
Hz) (4-MeC6H4), 6.76−6.94 (m), 7.29 (m) (40 H, Ph). 13C NMR
(100 MHz, C6D6, 298 K, ppm): δ 20.38, 20.47 (4-MeC6H4), 25.44
(THF-OCH2CH2), 67.44 (THF-OCH2CH2), 88.47, 90.21, 107.22,
108.23 (CC), 119.62, 122.47, 122.73, 127.96, 128.28, 128.33,
128.73, 128.87, 129.42, 130.19, 130.35, 132.33, 132.84, 134.17, 139.32,
142.28 (4-MeC6H4 and Ph). 29Si NMR (99 MHz, C6D6, 298 K, ppm):
δ −59.74, −59.61 (SiCCPh). IR (KBr plate, cm−1): ν 2161.3 (C
C). Anal. Calcd for C96H76N4OSi4 (9b·THF, Mr = 1414.00): C, 81.54;
H, 5.42; N, 3.96. Found: C, 81.22; H, 5.47; N, 3.71.
REFERENCES
■
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Synthesis of [2,4,6-Me3C6H2NSi(CCPh)2]2 (10a) and [(2,4,6-
Me3C6H2)3N3Si2(CCPh)4Li(THF)]−[Li(THF)4]+ (10b). PhCCLi
(6 mmol in 50 mL of Et2O) was freshly prepared in a manner similar
to that used in the synthesis of 5 and added to a solution of 4 (0.91 g,
2.0 mmol) in THF (6 mL) at −78 °C. The mixture was warmed to
room temperature and stirred for 12 h. The insoluble solid was
removed by filtration. The filtrate was evaporated to dryness under
reduced pressure. The residue was washed with n-hexane (8 mL)
followed by extraction with a THF/n-hexane (2 mL/6 mL) mixture.
The n-hexane washing solution was dried and analyzed to contain
Ph2PCCPh on the basis of 31P NMR data. The extract was stored at
−20 °C for 2 days to give colorless needle-shaped crystals of 10b·
toluene (0.063 g, 8% yield based on 4). The mother solution was
decanted into another bottle and kept at −20 °C for about 1 week,
producing colorless arris-piece crystals of 10a (0.192 g, 66% yield
(3) For the gas molecule elimination reactions, see: (a) Seyferth, D.;
Wiseman, G. H. Polym. Prepr. (Div. Polym. Chem., Am. Chem. Soc.)
1984, 25, 10−12. (b) Dando, N. R.; Perrotta, A. J.; Strohmann, C.;
Stewart, R. M.; Seyferth, D. Chem. Mater. 1993, 5, 1624−1630.
(4) For the organometallic base assisted reactions, see: (a) Rosenberg,
H.; Tsai, T.-T.; Adams, W. W.; Gehatia, M. T.; Fratini, A. V.; Wiff, D.
R. J. Am. Chem. Soc. 1976, 98, 8083−8087. (b) Klingebiel, U. J.
Organomet. Chem. 1978, 152, 33−38. (c) Wiseman, G. H.; Wheeler, D.
R.; Seyferth, D. Organometallics 1986, 5, 146−152. (d) Kosse, P.;
Popowski, E. Z. Anorg. Allg. Chem. 1992, 613, 137−148. (e) Shibley, J.
L.; West, R.; Tessier, C. A.; Hayashi, R. K. Organometallics 1993, 12,
3480−3484. (f) Shibley, J. L.; West, R.; Powell, D. R.; Tessier, C. A.
Heteroat. Chem. 1994, 5, 205−214. (g) Shibley, J. L.; West, R.; Belz, J.;
1
based on 4). Data for 10a are as follows. Mp: 242 °C. H NMR (400
MHz, C6D6, 298 K, ppm): δ 2.21 (s, 6 H, 4-MeC6H2), 3.20 (s, 12 H,
2,6-Me2C6H2), 6.95 (s, 4 H, C6H2), 6.80−6.90 (m), 7.32 (m) (20 H,
Ph). 13C NMR (100 MHz, C6D6, 298 K, ppm): δ 20.33, 20.69 (2,4,6-
Me3C6H2), 92.14, 107.39 (CC), 122.15, 128.24, 129.19, 129.46,
132.22, 133.65, 135.34, 137.05 (C6H2 and Ph). 29Si NMR (99 MHz,
C6D6, 298 K, ppm): δ −65.09 (SiCCPh). IR (KBr plate, cm−1): ν
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dx.doi.org/10.1021/om401095n | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
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(8) The lithium alkynyls R′CCLi (R′ = Ph, tBu, CH2CH2Ph) were
freshly prepared from the reaction of the corresponding alkynes with
nBuLi from −30 °C to room temperature within 3 h in a way similar
to that which we previously reported; see: Zhao, N.; Zhang, J.; Yang,
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(9) PhMe2SiCCPh can be prepared from double salt metathesis of
Me2SiCl2 with the respective Grignard reagents PhMgBr and PhC
CMgBr or by a direct silylation of terminal alkynes with aminosilanes
in the presence of zinc halides; see: (a) Hoffmann, F.; Wagler, J.;
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Konshin, V. V.; Komorov, N. V.; Rubin, M.; Brouwer, C.; Gevorgyan,
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(10) The 31P NMR data were measured at −32.93 ppm for Ph2PC
CPh, −34.52 ppm for Ph2PCCtBu, and −33.79 ppm for Ph2PC
CCH2CH2Ph. Ph2PCCPh and Ph2PCCtBu have been synthe-
sized from Pd- or Ni-catalyzed cross coupling of terminal alkynes with
chlorophosphanes; see: Beletskaya, I. P.; Afanasiev, V. V.; Kazankova,
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(12) The dissociation energy of the N−P bond is 617 21 kJ/mol,
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(15) Due to the quality of the crystals of 9b and 10a, only the
preliminary structures were given. The CIF data for these two
compounds have been deposited in the CSD as personal
communications (Depositor, Hongping Zhu, 2014, CCDC-986039
for 9b and CCDC-986040 for 10a).
(16) Głow
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ka, M. L.; Olczak, A.; Martynowski, D.; Kozłowska, K.;
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́
H
dx.doi.org/10.1021/om401095n | Organometallics XXXX, XXX, XXX−XXX