Alternative Synthesis and Structures of C-monoacetylenic Phosphaalkenes
4
14.1 Hz, P=C-CH3), 31.3 (s, para-C(CH3)3), 32.6 (d, JPC = 6.2 Hz, sured, 7784 unique (Rint = 0.0838) R1 = 0.0434 (IϾ2.0σ(I)), Rw =
meta-C(CH3)3), 35.0 (s, para-C(CH3)3), 38.0 (s, meta-C(CH3)3), 94.7
0.1267 (all data), GooF = 1.008, 257 parameters, 0 restraints.
2
3
(d, JPC = 28.2 Hz, acetylenic-C), 96.9 (d, JPC = 18.9 Hz, acetylenic-
4
Synthesis of Phosphaalkene Dimer (4): Bu4NF (1.0 M in THF, 0.17
mL, 0.17 mmol) was added to a THF solution (10 mL) of phosphaalk-
ene 3b (69 mg, 0.17 mmol). After stirring at room temperature for 30
min, the reaction mixture was filtered through a plug of silica (ethyl
acetate, 1% H2O). Cu(OAc)2·H2O (7 mg, 0.034 mmol) and TMEDA
(500μL) were added and the suspension was vigorously stirred. The
reaction was monitored by TLC and was complete after 12 h. The
organic phase was washed with saturated aqueous NH4Cl solution and
brine. The collected organic phases were dried (MgSO4) and purified
on a short silica column (pentane/ethyl acetate 95:5), yielding pure
bisphosphaalkene 4 as a slightly yellow solid in moderate yields
(29 mg, 0.044 mmol). Yield: 52%.
C), 121.7 (s, arom. meta-C, Mes*), 123.8 (d, JPC = 6.9 Hz, arom.
ipso-C, Ph), 128.0 (s, para-C, Ph), 128.2 (s, meta-C, Ph), 131.5 (d,
1
5JPC = 5.3 Hz, arom. ortho-C, Ph), 135.90 (d, JPC = 60.4 Hz, arom.
ipso C), 150.5 (s, arom. para-C, Mes*) 153.8 (s, arom. ortho-C, Mes*),
1
160.5 (d, JPC = 33.7 Hz, P=C). 31P{1H} NMR (161.8 MHz, CDCl3,
23 °C): δ = 284.0 (s). HR-MS (ESI): m/z 427.25261 [M+Na]+; calcd
for C28H37PNa 427.2521. Anal. Calcd. for [C28H37P·2H2O]; C, 76.33;
H, 9.38. Found C, 76.39; H, 9.84. λmax (CH2Cl2): 335 nm
Crystal Structure Analysis of (3a): Single crystals of 3a suitable for
X-ray diffraction were obtained by slow evaporation of a saturated
dichloromethane/acetonitrile solution. Compound 3a crystallized in the
monoclinic space group C2/c (No. 15), C28H37P, M = 404.55, crystal
dimensions = 0.20 ϫ 0.20 ϫ 0.30 mm, a = 53.882(3) Å, b = 6.1348(3)
Å, c = 36.151(2) Å, β = 122.653(2)°, V = 10061.3(10) Å3, Z = 16,
2θmax = 55.42°, ρ = 1.068 g·cm–1, μ(Mo-Kα) = 0.120 mm–1, F(000) =
3520.0, 60462 reflections measured, 11706 unique (Rint = 0.0670), R1
= 0.0505 (IϾ2.0σ(I)), Rw = 0.1517, GooF = 1.033), 557 parameters,
0 restraints.
1H NMR (399.8 MHz, CDCl3, 23 °C): δ = 1.32 (s, 18H, para-tert-
butyl), 1.34 (d, 4JPH = 15.8 Hz, 6H, P=CCH3), 1.45 (s, 36H, meta-tert-
butyl), 7.40 (s, 4H, arom. Mes*).13C NMR (100.5 MHz, CDCl3): δ =
3
0.27 (SiMe3), 25.9 (d, JPC = 14.2 Hz, P=C-CH3), 30.64 (s, para-
C(CH3)3), 32.82 (br.s., meta-C(CH3)3), 35.23 (br.s., para-C(CH3)3),
38.16 (br. s., meta-C(CH3)3), 92.80 (br.s, acetylenic), 96.13 (d, JPC
3
=
12.3 Hz, acetylenic), 119.70 (s, Mes*), 135.16 (br.s., Mes*) 153.40 (s,
1
Mes*) 154.02 (s, Mes*), 166.01 (d, JPC = 68.8 Hz, P=C). 31P{1H}
Synthesis of Phosphaalkene (3b): Phosphaalkene 2a (40 mg,
0.10 mmol) was dissolved in deaerated THF:DMF (5:5 mL). After ad-
dition of the catalyst, either [PdCl2(PPh3)] (3.5 mg, 0.005 mmol) or
[PdCl2(dppf)]·CH2Cl2 ((4 mg, 0.005 mmol) and CuI (2 mg,
0.01 mmol), NEt3/pyridine (1 mL of a 3:1 mixture) and ethynyltri-
methylsilane were added (35 mg 0.36 mmol). The reaction was moni-
tored by TLC until the starting material had disappeared (approxi-
mately 5 min for [PdCl2(dppf)]·CH2Cl2). The organic phase was
washed with saturated aqueous NH4Cl solution and brine. The organic
phases were dried (MgSO4). The residue was purified on a silica col-
umn (pentane) Phosphaalkene 3b was isolated in good yield as a color-
less solid (32 mg 0.078 mmol) Yield: 78%.
NMR (161.8 MHz, CDCl3, 23 °C): δ = 302.9 ppm. HR-MS (ESI):
m/z 677.43762 [M+Na]+; calcd for C44H64P2Na 677.43755. λmax
(CH2Cl2): 359 nm.
Crystal Structure Analysis of (4): Single crystals of 4 suitable for
X-ray diffraction were obtained by slow evaporation of a chloroform
solution at 4 °C. Compound 4 crystallized in the monoclinic space
group P21 (No. 4) as slightly yellow prisms, C44H64P2, M = 654.89,
crystal dimensions 0.13 ϫ 0.1 ϫ 0.07 mm, a = 18.683(4) Å, b =
12.223(3) Å, c = 18.775(4) Å, β = 106.539(3)°, V = 4110.0(16) Å3, Z
= 4, 2θmax= 53.1°, ρ = 1.058 g·cm–1, μ(Mo-Kα) = 0.133 mm–1, F(000)
= 1432, 60200 reflections measured, 16886 unique (Rint = 0.1021) R1
= 0.1497 (IϾ2.0σ(I)), Rw = 0.4337 (all data), GooF = 1.519, 742 pa-
rameters, 73 restraints.
Alternative Synthesis of (3b): To phosphaalkene 2a (390 mg,
1 mmol), [PdCl2(PPh3)2] (35 mg, 0.050 mmol) and CuI (19 mg,
0.10 mmol) deaerated NEt3 (15 mL) was added. Ethynyltrimethylsil-
ane (0.71 mL, 5 mmol) was added to the yellow suspension which
upon stirring overnight changed to a brown color. The solvent was
removed and the solid was redissolved in pentane and purified on a
silica column (pentane). 3b was isolated as a white solid (251 mg,
0.63 mmol). Yield 63%.
Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge Crystal-
lographic Data Centre as supplementary publication numbers CCDC-
890282 (2a), CCDC-890280 (2b), CCDC-890129 (3a), CCDC-890283
(3b) and CCDC-890281 (4). These data can be obtained free of
data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crys-
tallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK;
Fax: +44 1223 336033.
1H NMR (399.8 MHz, CDCl3, 23 °C): δ = 0.23 (s, 9H, SiMe3), 1.29
4
(d, JPH = 13.5 Hz, 3H, P=CCH3), 1.33 (s, 9H, para-tert-butyl), 1.48
(s, 18H, meta-tert-butyl), 7.41 (br. s., 2H, arom. Mes*).13C NMR
3
(100.5 MHz, CDCl3): δ = 0.27 (SiMe3), 25.1 (d, JPC = 13.8 Hz,
4
P=C-CH3), 31.44 (s, para-C(CH3)3), 32.70 (d, JPC = 6.9 Hz, meta-
Acknowledgment
C(CH3)3), 35.10 (s, para-C(CH3)3), 38.03 (br. s., meta-C(CH3)3),
4
3
101.46 (d, JPC = 16.1 Hz, acetylenic C2), 109.57 (d, JPC = 27.7 Hz,
The work was supported by COST initiative PhoSciNet (CM0802),
Uppsala University U3MEC Molecular Electronics Priority Initiative,
Swedish Research Council, the Göran Gustafsson Foundation. A.O.
would like to thank the Austrian Science Fund (FWF) for financial
support through an Erwin-Schrödinger Fellowship (J 3193). We thank
H. Luftmann for HR-MS.
1
acetylenic C1), 121.76 (s, arom. meta C), 135.90 (d, JPC = 60.7 Hz,
arom. ipso-C), 150.53 (s, arom. para-C) 153.76 (s, arom. ortho-C),
1
160.78 (d, JPC = 34.6 Hz, P=C). 31P{1H} NMR (161.8 MHz, CDCl3,
23 °C): δ = 288.5 (s). λmax (CH2Cl2): 309 nm
Crystal Structure Analysis of (3b): Single crystals suitable for X-ray
diffraction were obtained by slow evaporation of pentane/chloroform
at 4 °C. Phosphaalkene 3b crystallized in the monoclinic space group
P21/c (No. 14), C25H41PSi, M = 400.64, crystal dimensions 0.18 ϫ
0.2 ϫ 0.2 mm, a = 9.2485(6) Å, b = 21.6460(15) Å, c = 12.7440(9)
Å, β = 98.688(1)°, V = 2522.0(3) Å3, Z = 4, 2θmax= 62.5°, ρ = 1.055
g·cm–1, μ(Mo-Kα) = 0.164 mm-1, F(000) = 880, 47957 reflections mea-
References
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Chem. Soc. 2006, 128, 8836–8844; b) V. A. Wright, D. P. Gates,
Angew. Chem. Int. Ed. 2002, 41, 2389–2392; c) D. P. Gates, in
Z. Anorg. Allg. Chem. 2012, 2219–2224
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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