N. Millot, C. C. Santini, B. Fenet, J. M. Basset
FULL PAPER
3
8.2 Hz, 2 H, o-C6H5), 2.80 (q, JH-H ϭ 7.1 Hz, 4 H, CH2), 0.82 (t,
Conclusion
3JH-H ϭ 7.1 Hz, 6 H, CH3) ppm. 13C NMR: δ ϭ 142.4 (s, i-C6H5),
130.3 (s, m-C6H5), 123.1 (br. s, p-C6H5), 116.4 (s, o-C6H5), 49.4 (s,
CH2), 11.4 (s, CH3) ppm. 15N NMR: δ ϭ 71 (s, NEt2Ph) ppm.
The presence of several species in equilibrium in a solu-
tion of (C6F5)3B and R2NPh (1: 1) has been established by
several NMR experiments. In the case of dimethylaniline,
besides free B(C6F5)3 and Me2NPh, the 1:1 adduct
(C6F5)3B·NMe2Ph and an iminium salt [PhCH3Nϭ
CH2]ϩ[HB(C6F5)3]Ϫ have been identified. With diethyl-
aniline, 40% of the products were unchanged (C6F5)3B
B(C6F5)3: 11B NMR: δ ϭ 59 (br. s, B(C6F5)3] ppm. 13C NMR: δ ϭ
1
1
148.8 (d, JC-F ϭ 243 Hz, o-C6F5), 141.5 (d, JC-F ϭ 230 Hz, p-
C6F5), 137.7 (d, JC-F ϭ 247 Hz, m-C6F5) ppm. 19F NMR: δ ϭ
1
Ϫ128.6 (br. s, 6 F, o-C6F5), Ϫ141.7 (br. s, 3 F, p-C6F5), Ϫ160.0 (br.
s, 6 F, m-C6F5) ppm.
[A1, (E)-isomer]: 1H NMR (20%): δ ϭ 7.88 (t, 3JH-H ϭ 7.9 Hz, 1 H,
and
Et2NPh,
30%
were
the
iminium
salt
3
H-CϭN), 6.92 (m, m- and p-C6H5), 6.17 (d, JH-H ϭ 7.2 Hz, 2 H,
[HB(C6F5)3]Ϫ(HNEt2Ph)ϩ, and the remaining 30% were
converted into the zwitterionic stereoisomers (E)- and (Z)-
[PhEtNϩϭCH-CH2BϪ(C6F5)3] in a 3:2 ratio. In the pres-
ence of a protic compound this equilibrium is totally dis-
placed towards the ionic form [RO-B(C6F5)3]Ϫ[HNEt2Ph]ϩ.
3
o-C6H5), 3.15 (br. m, 2 H, CH2-B), 2.60 (q, JH-H ϭ 7.25 Hz, 2 H,
CH2), 0.40 (t, JH-H ϭ 7.2 Hz, 3 H, CH3) ppm. 11B NMR: δ ϭ
3
Ϫ12.9 (s, [-CH2-B(C6F5)3]Ϫ) ppm. 13C NMR: δ ϭ 188.6 (s, CϭN),
136.5 (s, i-C6H5), 131 (s, m-C6H5), 130.2 (s, p-C6H5), 124.2 (s, o-
C6H5), 58.5 (s, CH2), 34.5 (br, CH2-B), 12.7 (s, CH3) ppm; C6F5
signals not resolved. 15N NMR: δ ϭ 209.5 (s, EtPhNϩϭCH-) ppm.
3
19F NMR: δ ϭ Ϫ132.6 (d, JF-F ϭ 19 Hz, 6 F, o-C6F5), Ϫ158.6
Experimental Section
(br. s, 3 F, p-C6F5), Ϫ164.8 (br. s, 6 F, m-C6F5) ppm.
3
[A2, (Z)-isomer]: 1H NMR (10%): δ ϭ 7.91 (t, JH-H ϭ 8.5 Hz, 1
All operations were carried out under an argon atmosphere using
glovebox (Jacomex or MBraun) or vacuum-line techniques. Tolu-
ene and pentane were distilled under argon from Na/K alloy, de-
gassed and stored under argon over Na (toluene) or 3 A molecular
sieves (pentane). C6D6 (SDS Ϫ 99.6%) and CD2Cl2 (SDS Ϫ 99.6%)
3
H, H-CϭN), 6.92 (m, m-C6H5), 6.85 (t, JH-H ϭ 7.7 Hz, 1 H, p-
3
C6H5), 6.36 (d, JH-H ϭ 7.9 Hz, 2 H, o-C6H5), 3.45 (br.m, 2 H,
3
3
CH2-B), 3.10 (q, JH-H ϭ 7.4 Hz, 2 H, CH2), 0.35 (t, JH-H
ϭ
˚
7.2 Hz, 3 H, CH3) ppm. 11B NMR: δ ϭ Ϫ12.6 (s, [-CH2-
B(C6F5)3]Ϫ) ppm. 13C NMR: δ ϭ 189.2 (s, CϭN), 142.4 (s, i-C6H5),
130.9 (s, m-C6H5), 130.5 (s, p-C6H5), 122.9 (s, o-C6H5), 48.3 (s,
CH2), 34.5 (br, CH2-B), 11.8 (s, CH3) ppm; C6F5 signals not re-
were degassed by three ‘‘freeze-pump-thaw’’ cycles and dried over
˚
freshly regenerated 3 A molecular sieves. NEt2Ph (Aldrich Chem-
icals, 98%) and NMe2Ph (Aldrich Chemicals, 99%) were dried over
KOH, distilled under vacuum and used immediately. B(C6F5)3
(Merck Chemicals, Ͼ 97%) was dried using Me3SiCl,[38] purified
by vacuum sublimation and controlled by 19F NMR spectroscopy
before use. The NMR spectra were recorded with Bruker AC
200 MHz (19F), AC 300 MHz (1H, 13C), DRX 300 MHz (11B) and
DRX 500 MHz (1H, 13C, 11B, 15N 2D NMR) spectrometers. Chem-
ical shifts are reported in ppm and referenced to residual solvent
resonances (C6D6: δ ϭ 7.15 ppm for 1H, δ ϭ 128 ppm for 13C;
3
solved. 19F NMR: δ ϭ Ϫ132.6 (d, JF-F ϭ 19 Hz, 6 F, o-C6F5),
Ϫ158.6 (br. s, 3 F, p-C6F5), Ϫ164.8 (br. s, 6 F, m-C6F5) ppm. 15N
NMR: δ ϭ 210.2 (s, EtPhNϩϭCH-) ppm.
1
[HB(C6F5)3]؊: H NMR: δ ϭ 3.90 (br, 1 H) ppm. 11B NMR: δ ϭ
1
3
Ϫ23.6 (d, JB-H ϭ 77.5 Hz) ppm. 19F NMR: δ ϭ Ϫ132.2 (d, JF-
3
ϭ 22 Hz, 6 F, o-C6F5), Ϫ159.5 (t, JF-F ϭ 22 Hz, 3 F, p-C6F5),
F
Ϫ164.3 (m, 6 F, m-C6F5) ppm; δ ϭ Ϫ133.5 (br. m, 6 F, o-C6F5),
Ϫ161.2 (br. m, 3 F, p-C6F5), Ϫ165.4 (br. m, 6 F, m-C6F5) ppm.
1
CD2Cl2: δ ϭ 5.32 ppm for H, δ ϭ 53.8 ppm for 13C), or external
Preparation of IMe: In an NMR tube, B(C6F5)3 (97 mg, 0.19 mmol)
was dissolved in 0.4 mL of C6D6. NMe2Ph (24 µL, 0.19 mmol) was
then added with a syringe to give a pale pink solution.
standards (19F: CFCl3; 11B: BF3·OEt2; 15N: N,N-dimethylformam-
ide).
1
3
2D COSY experiments were acquired with the standard Bruker
COSYgp experiment and processed in absolute mode. 2D HSQC
experiment were acquired with the standard Bruker inviegts experi-
NMe2Ph: H NMR: δ ϭ 7.31 (dd, JH-H ϭ 7.0 Hz, 2 H, m-C6H5),
3
3
6.88 (t, JH-H ϭ 7.0 Hz, 1 H, p-C6H5), 6.72 (d, JH-H ϭ 8.5 Hz,
2 H, o-C6H5), 2.62 (s, 3 H, CH3) ppm. 15N NMR: δ ϭ 43.7 (s,
ment and processed in phases mode. 2D HMBC experiment were NMe2Ph) ppm.
acquired with the standard Bruker inv4gplrnd and processed in ab-
3
(C6F5)3B·NMe2Ph: 1H NMR: δ ϭ 7.17 (d, JH-H ϭ 8.5 Hz, 2 H, o-
solute mode, as shown in Table 2.
3
3
C6H5), 6.8 (t, JH-H ϭ 8.2 Hz, 1 H, p-C6H5), 6.67 (t, JH-H
ϭ
8.4 Hz, 2 H, m-C6H5), 2.55 (s, 6 H, CH3) ppm. 11B NMR: δ ϭ
Ϫ2.9 (s, (C6F5)3B-NMe2Ph) ppm. 15N NMR: δ ϭ 52.3 [s, (C6F5)3B-
Table 2. Standard parameters for the 2D NMR experiments
NMe2Ph] ppm. 19F NMR: δ ϭ Ϫ132.7 (d, JF-F ϭ 20 Hz, 6 F, o-
3
1H-13C
1H-15N
1H-11B
3
C6F5), Ϫ159.1 (t, JF-F ϭ 20 Hz, 3 F, p-C6F5), Ϫ165.4 (m, 6 F, m-
C6F5) ppm.
D6
50ms
100 ms
25 ms
[PhMe(N؍
CH2)]؉[HB(C6F5)3]؊: 11B NMR:
δ ϭ Ϫ23.9 (s,
Gradients
Row data size
20Ϫ20Ϫ10
4096 ϫ 1024
70Ϫ30Ϫ50
4096 ϫ 256
60Ϫ20Ϫ6567
2048 ϫ 512
3
[HB(C6F5)3]Ϫ) ppm. 19F NMR: δ ϭ Ϫ132.1 (d, JF-F ϭ 22 Hz, 6
3
F, o-C6F5), Ϫ159.7 (t, JF-F ϭ 22 Hz, 3 F, p-C6F5), Ϫ164.4 (m, 6
F, p-C6F5); δ ϭ Ϫ133.3 (br. m, 6 F, o-C6F5), Ϫ161.6 (br. m, 3 F,
p-C6F5), Ϫ165.4 (br. m, 6 F, m-C6F5) ppm.
Reactions of Equimolar Amounts of [B(C6F5)3؉NEt2Ph] (I) and
[B(C6F5)3؉NMe2Ph] (IMe
)
Preparation of I: In an NMR tube, B(C6F5)3 (75 mg, 0.15 mmol) Acknowledgments
was dissolved in 0.4 mL of C6D6. NEt2Ph (23.3 µL, 0.15 mmol) was
We thank Dr. R. Andersen, Pr. M. Ciufolini and Pr. A. Smith for
then added with a syringe to give a pink solution after agitation.
fruitful discussions. We are also grateful to CNRS and ESCPE
Lyon for financial support, and to the French Ministry for Educa-
tion and Research for a fellowship (N. M.).
1
3
NEt2Ph: H NMR (C6D6): δ ϭ 7.17 (dd, JH-H ϭ 7.9 Hz, 2 H, m-
3
3
C6H5), 6.9 (t, JH-H ϭ 7.2 Hz, 1 H, p-C6H5), 6.66 (d, JH-H
ϭ
3334
Eur. J. Inorg. Chem. 2002, 3328Ϫ3335