η2-Phosponioalkene-Palladium(0) Complexes
Organometallics, Vol. 17, No. 4, 1998 681
synthesis;21 the present catalysis is a general and
convenient method for the preparation of these salts.
In conclusion, we have shown that η2-phosphonioalk-
ene-palladium(0) complexes were readily produced
from oxidative addition of haloalkenes to palladium(0)-
phosphine complexes, from the interaction of haloalk-
enes with palladium(II) species, and from direct reac-
tions of alkenylphosphonium halides with palladium(0)
species. In the catalytic synthesis of alkenylphospho-
nium halides from alkenyl halides and triphenylphos-
phine, η2-phosphonioalkene-palladium(0) complexes
and the corresponding oxidative-addition products ap-
pear to be the main intermediates in solutions. In view
of the large number of palladium-phosphine-mediated
coupling reactions involving haloalkenes, it is important
to see the effect of the formation of η2-phosphonioalkene-
palladium(0) complexes on the catalytic activity of these
reactions. Investigations in this direction are underway.
(300 MHz, CDCl3): δ 2.35 (m, 9 H), 3.69 (m, 1 H), 3.96 (m, 1
H), 6.29 (m, 5 H), 6.05-7.17 (m, 36 H). 13C{1H} NMR (75 MHz,
1
2
CDCl3): δ 21.22 (m), 34.54 (m, J CP ) 78.0 Hz, J CP ) 33.2
2
2
2
Hz, J CP ) 6.7 Hz), 69.83 (q, J CP ) 29.0 Hz, J CP ) 2.9 Hz).
IR (KBr): 1596, 1495, 1449, 1397 cm-1. MS (FAB): m/e 1121
(M+), 817, 407.
Important
spectral
data
for
[Pd(CH3CHd
CHPPh3)(PPh3)2]+Br- (3) are as follows. 1H NMR (300 MHz,
CDCl3): δ 1.37 (q, 1J HP ) 7.1 Hz, 4J HP ) 5.9 Hz, 3 H), 2.55 (m,
1 H), 3.62 (m, 1 H), 7.03-7.3 (m, 45 H). 13C{1H} NMR (75
MHz, CDCl3): δ 21.48 (dt, 3J CP ) 13.5 Hz, 3J CP ) 4.5 Hz), 39.62
1
2
2
(m, J CP ) 76.7 Hz, J CP ) 31.4 Hz, J CP ) 6.7 Hz), 68.82 (d,
2J CP ) 28.0 Hz). IR (KBr): 1637, 1588, 1481, 1435 cm-1. MS
(FAB): m/e 933 (M+), 630, 303.
Syn th esis of (tr a n s-P h CHdCHP P h 3)P d (P P h 3)(X) (5).
A round-bottom flask containing Pd(PPh3)2(p-CH3OC6H4)I
(0.432 g, 0.50 mmol) and â-bromostyrene (0.182 g, 1.00 mmol)
was purged by nitrogen gas three times. THF (5 mL) was then
syringed into the flask, and the solution was stirred at room
temperature for 105 h. During the reaction period, the color
of the solution changed gradually from pale yellow to orange
red and a precipitate was formed. The precipitate was filtered
off, and the filtrate was concentrated. Addition of hexane led
to the formation of orange precipitate, which was collected on
a glass filter and was washed with ether (20 mL). Recrystal-
lization from a mixture of dichloromethane and hexane gave
deep orange-red and yellow crystals. A yellow crystal was
selected for X-ray analysis. The yield of the yellow crystals
[(E)-PhCHdCHPPh3+]Pd(PPh3)(X) (0.095 g), where X is a
mixture of Br and I, is 24% assuming that X ) I.
Syn th esis of P d (tr a n s-P h CHdCHP P h 3)(P P h 3)Br (5)
fr om P d (d b a )2 a n d tr a n s-P h CH dCHP P h 3+Br -. To a
round-bottom flask containing Pd(dba)2 (0.287 g, 0.50 mmol),
triphenylphosphine (0.131 g, 0.50 mmol), and trans-
PhCHdCHPPh3+Br- (0.50 mmol) under nitrogen was added
CH2Cl2 (5 mL). The solution was then stirred at room
temperature for 3 h. During the reaction period, the color of
the solution changed gradually from red-brown to deep yellow
and a small amount of black precipitate was also produced.
The solid was filtered off, and the solvent was removed in
vacuo. The residue was collected on a glass filter and was then
washed by ether (ca. 10 mL) three times to give the crude
product. Recrystallization from dichloromethane and ether
afforded the desired pure product in 81% yield. 1H NMR (400
MHz, CDCl3): δ 3.24 (ddd, J ) 19.0 Hz, J ) 10.3 Hz, J ) 4.4
Hz, 1 H), 3.53 (ddd, J ) 12.6 Hz, J ) 10.3 Hz, J ) 7.6 Hz, 1
H), 5.31 (s, 2 H), 6.57 (d, J ) 7.6 Hz, 2 H), 6.88 (t, J ) 7.4 Hz,
2 H), 6.96 (t, J ) 7.2 Hz, 1 H), 7.00 (dd, J ) 10.0 Hz, J ) 7.6
Hz, 6 H), 7.12 (t, J ) 6.8 Hz, 6 H), 7.21 (t, J ) 6.8 Hz, 3 H),
7.46 (td, J ) 7.8 Hz, J ) 2.9 Hz, 6 H), 7.59 (td, J ) 7.4 Hz, J
) 1.2 Hz, 3 H), 7.97 (dd, J ) 12.4 Hz, J ) 8.0 Hz, 6 H). 13C{1H}
Exp er im en ta l Section
All reactions were performed under dry nitrogen, and all
solvents were dried by standard methods. 1H and 13C NMR
experiments were performed on a Varian Gemini 300 or a
Varian Unity 400 spectrometer, while 31P NMR experiments
were recorded on a Bruker AM-400 spectrometer using 85%
H3PO4 as an external standard. Infrared spectra were ob-
tained on a Bomem MB-100 spectrophotometer, while mass
spectra were recorded on a J EOL J MS-D100 system. Melting
point measurements were carried out on a Mel-Temp ap-
paratus and are uncorrected. Microanalytical data were
obtained on a Heraeus CHN-O-RAPID instrument.
1-Bromopropene and R-bromostyrene (Aldrich), 2-bromo-2-
butene (mixture of isomers), cis-2-ethoxybromoethylene, 2-bro-
mopropene, and triphenylphosphine (J anssen), and â-bro-
mostyrene (mixture of isomers) (TCI) were used as purchased.
Pd(PPh3)4,23 Pd(dba)2,24 and PdI(p-CH3OC6H4)(PPh3)2 were
prepared according to reported methods.25
Syn th esis of [(tr a n s-P h CHdCHP P h 3)P d (P P h 3)2]+Br -
(1) fr om P d (P P h 3)4 a n d P h CHdCHBr . To a round-bottom
flask containing Pd(PPh3)4 (0.55 g, 0.48 mmol) and â-bro-
mostyrene (mixture of trans and cis isomers, 0.13 g, 0.71 mmol)
under nitrogen was added THF (5 mL) via a syringe. The
system was further purged by nitrogen gas three times and
was heated at 43 °C for 18 h. The precipitate was filtered and
was washed by ether to afford an air-sensitive pale yellow
product (0.45 g) in 88% yield. Crystals suitable for X-ray
analysis were grown from an acetonitrile/ether mixture.
Selected spectral data and microanalysis data for this complex
are as follows. 1H NMR (300 MHz, CDCl3): δ 3.62 (m, 1 H),
4.27 (m, 1 H), 6.4 (m, 5 H), 6.86-7.65 (m, 45 H). 13C{1H} NMR
1
2
NMR (75 MHz, CD2Cl2): δ 27.17 (dd, J PC ) 80.6 Hz, J PC
)
)
37.6 Hz), 53.44 (s), 61.35 (d, 2J PC ) 6.1 Hz), 124.57 (dd, 1J PC
1
2
(75 MHz, CDCl3): δ 33.72 (m, J CP ) 78.0 Hz, J CP ) 33.1 Hz,
4
3
88.5 Hz, J PC ) 3.5 Hz), 124.85, 125.23, 128.01 (d, J PC ) 9.2
2J CP ) 2.7 Hz), 69.99 (q, J CP ) 34.8 Hz, J CP ) 6.6 Hz). 31P-
{1H} NMR (162 MHz, CDCl3): δ 22.24 (dd, 3J PP ) 5.5 Hz, 3J PP
) 1.7 Hz), 26.25 (dd, 3J PP ) 15.2 Hz, 3J PP ) 1.7 Hz), 27.33 (dd,
2
2
Hz), 128.33, 129.02, 129.26 (d, 2J PC ) 12.1 Hz), 133.43 (d, 4J PC
2
3
) 2.8 Hz), 134.20 (d, J PC ) 14.0 Hz), 134.49 (d, J PC ) 9.8
1
3
Hz), 135.89 (d, J PC ) 29.6 Hz), 143.88 (d, J PC )12.2 Hz).
3J PP ) 15.2 Hz, J PP ) 5.5 Hz). IR (KBr): 1618, 1586, 1478,
3
31P{1H} NMR (121 MHz, CD2Cl2): δ 21.20 (d, J PP ) 7.0 Hz),
3
1427 cm-1
.
MS (FAB): m/e 996 (M+ - Br + 1), 365. Anal.
3
21.68 (d, J PP ) 7.0 Hz). IR (KBr): 3039, 1586, 1480, 1434,
Calcd for C62H52BrP3Pd: C, 69.18; H, 4.87. Found: C, 68.47;
H, 4.98.
1181, 1099, 849, 746, 720, 691 cm-1. MS (FAB): m/z 733 [M
- Br]+. Anal. Calcd for PdBrP2C44H37‚CH2Cl2: C, 60.12; H,
4.37. Found: C, 60.34; H, 4.40. Mp: 120-122 °C dec.
Syn th esis of tr a n s-P h CHdCHP P h 3+Br -. A round-bot-
tom flask containing Pd(PPh3)4 (0.0577 g, 0.050 mmol), â-bro-
mostyrene (0.183 g, 1.00 mmol), and triphenylphosphine (0.262
g, 1.00 mmol) was purged with nitrogen gas three times.
Toluene (5 mL) was then syringed into the flask, and the
solution was heated to 100 °C with stirring for 15 h. The
solvent was removed in vacuo, and the residue was then
washed with ether (ca. 10 mL) three times to give the desired
pure product (0.278 g, 63% yield). Spectral data for trans-
The
complexes
{Pd[trans-PhCHdCHP(p-tolyl)3][P(p-
tolyl)3]2}+Br- (2) and [Pd(CH3CHdCHPPh3)(PPh3)2]+Br- (3)
were prepared in a manner similar to the above procedure.
Both 2 and 3 are thermally unstable and decompose even in
the solid state. Complete characterization of these species is
difficult. Important spectral data for 2 are as follows: 1H NMR
(23) Coulson, D. R. Inorg. Synth. 1972, 13, 121.
(24) Takahashi, Y.; Ito, T.; Sakai, S.; Ishii, Y. J . Chem. Soc. D 1970,
1065.
(25) Fitton, P.; Rick, E. A. J . Organomet. Chem. 1971, 28, 287.
Huang, Chien-Chih
