Insertion reactions of allenes with palladium aryl complexes [PdI(Ph)(PPh3)]2 and PdI(Ph)(dppe)

Article abstract of DOI:10.1021/om800030a

Treatment of [PdI(Ph)(PPh₃)]₂ with allenes CH ₂=C=CHR (R = CMe₃, CO₂Et, P(O)(OEt) ₂, and SO₂Ph) in dichloromethane at room temperature produces a mixture of cis and trans isomers of the π-allyl palladium complexes PdI(η³-CH₂C(Ph)CHR)(PPh₃) in which the R group is anti to the Ph group. The disubstituted alienes MeCH=C=CHR (R = P(O)(OEt)₂ and SO₂Ph) similarly react with [PdI(Ph)(PPh₃)]₂ to give the π-allyl palladium complexes PdI(η³-MeCHC(Ph)CHR)(PPh₃) in which the R group is anti and the Me group is syn to the Ph group. PdI(Ph)(dppe) alone was found to be unreactive toward allenes such as CH₂=C=CHSO ₂Ph and MeCH=C=CHSO₂Ph at room temperature. In contrast, in the presence of TIPF₆, PdI(Ph)(dppe) readily reacts with allenes CH₂=C=CHR (R = CMe₃, CO₂Et, COPh, and SO ₂Ph) and MeCH=C=CHSO₂Ph to give the π-allyl palladium complexes [Pd(η³-CH₂C(Ph)CHR)(dppe)]PF₆ and [Pd(η³-MeCHC(Ph)CHR)(dppe)]PF₆, respectively. Although mechanistically possible, vinyl complexes were not observed as the insertion products in all cases. The substituents of allenes appear to have no effect on the reaction pathways, at least for the allenes used in this study. The insertion reactions involving PdI(Ph)(PR₃)(allene) have been studied by computational chemistry using the model complex PdI(Ph)(MeCH=C= CHSO₂H)(PH₃).

Full text of DOI:10.1021/om800030a

2614
Organometallics 2008, 27, 2614–2626
Insertion Reactions of Allenes with Palladium Aryl Complexes
[PdI(Ph)(PPh3)]2 and PdI(Ph)(dppe)
Tao Bai,† Liqin Xue,‡ Peng Xue,‡ Jun Zhu,‡ Herman Ho-Yung Sung,‡ Shengming Ma,*,†
Ian Duncan Wiliams,‡ Zhenyang Lin,*,‡ and Guochen Jia*,‡
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese
Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, People’s Republic of China, and Department of
Chemistry, The Hong Kong UniVersity of Science and Technology, Clear Water Bay, Kowloon,
Hong Kong, People’s Republic of China
ReceiVed January 12, 2008
Treatment of [PdI(Ph)(PPh3)]2 with allenes CH2dCdCHR (R ) CMe3, CO2Et, P(O)(OEt)2, and SO2Ph)
in dichloromethane at room temperature produces a mixture of cis and trans isomers of the π-allyl palladium
complexes PdI(η3-CH2C(Ph)CHR)(PPh3) in which the R group is anti to the Ph group. The disubstituted
allenes MeCHdCdCHR (R ) P(O)(OEt)2 and SO2Ph) similarly react with [PdI(Ph)(PPh3)]2 to give the
π-allyl palladium complexes PdI(η3-MeCHC(Ph)CHR)(PPh3) in which the R group is anti and the Me
group is syn to the Ph group. PdI(Ph)(dppe) alone was found to be unreactive toward allenes such as
CH2dCdCHSO2Ph and MeCHdCdCHSO2Ph at room temperature. In contrast, in the presence of TlPF6,
PdI(Ph)(dppe) readily reacts with allenes CH2dCdCHR (R ) CMe3, CO2Et, COPh, and SO2Ph) and
MeCHdCdCHSO2Ph to give the π-allyl palladium complexes [Pd(η3-CH2C(Ph)CHR)(dppe)]PF6 and
[Pd(η3-MeCHC(Ph)CHR)(dppe)]PF6, respectively. Although mechanistically possible, vinyl complexes
were not observed as the insertion products in all cases. The substituents of allenes appear to have no
effect on the reaction pathways, at least for the allenes used in this study. The insertion reactions involving
PdI(Ph)(PR3)(allene) have been studied by computational chemistry using the model complex
PdI(Ph)(MeCHdCdCHSO2H)(PH3).
of allenes. Occasionally attachment of aryl to the terminal
carbons of allenes was also observed.17,18 The substituents of
Introduction
Allenes are an interesting class of organic compounds with
unusual chemical properties due to their two cumulated double
bonds. There have been much interest in using them as starting
materials for the synthesis of various target molecules of
industrial and biological significance.1,2 Among their various
reactions, palladium-catalyzed coupling reactions of allenes with
aryl halides and related substrates have received much attention.
These reactions are usually initiated by palladium phosphine
complexes such as Pd(PPh3)4, Pd(dba)2/PPh3, and Pd(OAc)2/
PPh3. A variety of products can be obtained from the coupling
reactions, for example, 1,3-dienes,3 2-arylamines,4 butenolides,5
furans,6 dihydrofuran,7 benzofuran,8 pyrrolidines,9 tetrasubsti-
tuted allenes,10 cyclopropane or cyclopentene derivatives,11
iminolactones and γ-hydroxy-γ-lactams,12 4-substituted-2,5-
dihydrofurans or vinylic epoxides,13 oxazolines,14 epoxyoxin-
doles,15 and other interesting polycyclic compounds,16 to name
a few.
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2007, 9, 529. (b) Chang, H.-T.; Jayanth, T. T.; Cheng, C.-H. J. Am. Chem.
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Lett. 2006, 8, 3627. (p) Liu, Z.; Wasmuth, A. S.; Nelson, S. G. J. Am.
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128, 1139. (t) Sieber, J. D.; Morken, J. P. J. Am. Chem. Soc. 2006, 128,
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In most of the catalytic reactions mediated by these phosphine
complexes, the aryl group is transferred to the central carbon
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128, 1464. (b) Evans, P.; Hogg, P.; Grigg, R.; Nurnab, M.; Hinsley, J.;
Sridharan, V.; Suganthan, S.; Korn, S.; Collard, S.; Miur, J. E. Tetrahedron
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* Corresponding authors. E-mail: masm@mail.sioc.ac.cn (S.M.); chzln@
ust.hk (Z.L.); chjiag@ust.hk (G.J.).
† Shanghai Institute of Organic Chemistry.
‡ The Hong Kong University of Science and Technology.
(1) Selected recent reviews: (a) Yamamoto, Y.; Radhakrishnan, U. Chem.
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10.1021/om800030a CCC: $40.75
2008 American Chemical Society
Publication on Web 05/03/2008

Insertion Reactions of Allenes with Pd Aryl Complexes
Organometallics, Vol. 27, No. 11, 2008 2615
complexes such as [PdCl(C6H4C5H4N)]220 and from the reaction
of CH2dCdCHPh with PdI(C6H3-3,5-Me2)(bipy)/AgBF4.21 The
reaction of PdX(Ph)(PEt3)2 with 1,2-propadiene in the presence
of silver tetrafluoroborate to give the cationic η3-allylic complex
[Pd(PEt3)2(η3-CH2CPhCH2)]BF4 was briefly mentioned by
Stevens et al.22 We noted that insertion of simple allenes such
as CH2dCdCH2 and CH2dCdCMe2 into Pd-H, Pd-Me,
Pd-vinyl, Pd-acyl, and Pd-allyl complexes containing phos-
phine ligands to give allyl complexes has been reported for
complexes such as PdH(PCy3)2(P(O)(OCMe2CMe2O)),23 Pd-
ClMe(PPh3)2,24 [PdMe(MeCN)(dppp)]BF4,24 Pd(O2CCF3)-
Scheme 1
allenes as well as reaction conditions could have a drastic effect
on the regiochemistry of the coupling reactions, as illustrated
in Scheme 1 by the reactions of A3 and B10 with PhI catalyzed
by Pd(PPh3)4 to give C and D, respectively.
( C ( P h ) d C H 2 ) ( P P h 2 P y ) 2 , 2 5
[ P d ( C ( O ) C 6 H 4 - p -
Me)(MeCN)(PPh3)2]BF4,24 and PdCl(η3-C3H5)(PPh3).26
To better understand the mechanisms of coupling reactions
of aryl halide and allenes catalyzed by Pd/PPh3 systems, it is
obviously of interest to further study the insertion reactions of
allenes with complexes containing phosphine ligands. In
reported coupling reactions of aryl halides with allenes catalyzed
by Pd/PPh3 systems, the Pd/PPh3 ratio varies from 1:1 to 1:4.
Insertion reactions of Pd(II) complexes with unsaturated sub-
strates usually proceed through four-coordinate species,28 while
the possibility involving five-coordinate species has also been
occasionally proposed.29 Thus it is reasonable to imagine that
the insertion reactions involved in catalytic coupling reactions
of aryl halide (ArX) with allenes catalyzed by Pd/PPh3 systems
could proceed through neutral four-coordinate monophosphine
intermediates PdX(Ar)(PR3)(allene), five-coordinate bisphos-
phine intermediates PdX(Ar)(PR3)2(allene), or cationic four-
coordinate bisphosphine intermediates [Pd(Ar)(PR3)2(allene)]+.
For this purpose, we have studied the reactions of a series of
allenes with [PdI(Ph)(PPh3)]2 and PdI(Ph)(dppe) in either the
absence or presence of an iodide abstractor. Through the study,
we hope (i) to provide supporting evidence for the insertion
reactions of allenes into Pd-Ar bonds proposed in the mech-
anisms of coupling reactions of aryl halides with allenes and
(ii) to find out if substituents on allenes affect the pathways of
allene insertions, thereby causing the different regiochemistry
observed in the coupling reactions of allenes with aryl halides.
It is generally believed that the catalytic reactions proceed
by initial oxidative addition of aryl halides to Pd(0) species to
give aryl palladium complexes. For reactions giving products
with the aryl group attached to the central carbon of allenes,
insertion of allenes into Pd-Ar bonds to give π-allyl intermedi-
ates has often been proposed as one of the most important
fundamental steps. For reactions giving products with the aryl
group attached to the terminal carbon of allenes, insertion of
allenes into Pd-Ar bonds to give vinyl intermediates has been
proposed or implied as one of the most important fundamental
steps in some of the catalytic reactions.
In supporting the proposed mechanism, oxidative addition
of aryl halide to palladium(0) phosphine complexes has been
established; for example, Pd(PPh3)4 readily undergoes oxidative
addition to ArI to give aryl complexes Pd(Ar)I(PPh3)2.19 How-
ever, experimental evidence for the insertion of allenes into
Pd-Ar bonds is still weak since reported examples of insertion
reactions of Pd-aryl complexes containing phosphine ligands
are surprisingly still very rare, despite their importance in
catalytic reactions and a substantial amount of reported work
on allene insertion reactions of palladium complexes.20–27 In
fact, only a few examples of insertion of allenes into Pd-aryl
bonds have been reported. Allyl complexes were obtained from
the reactions of CH2dCdCMe2 with cyclometalated palladium
Results and Discussion
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Reactions of Allenes with [PdI(Ph)(PPh3)]2. To study allene
insertion reactions involving neutral four-coordinate monophos-
phine intermediates PdX(Ar)(PR3)(allene), we have studied the
reactions of [PdI(Ph)(PPh3)]2 (1) with allenes containing either
electron-donating or electron-withdrawing groups. The chloro-
bridged dinuclear complexes [PdCl(Ph)L]2 (L ) PPh3, PMePh,
or PBu3) readily undergo bridge cleavage reactions with L to
give trans-PdCl(Ph)L2.30 Thus we expected that the iodo-bridged
dinuclear complex [PdI(Ph)(PPh3)]2 (1)31 will react with allenes
to give intermediates PdI(Ph)(PPh3)(allene), which may undergo
allene insertion reactions.
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When a mixture of [PdI(Ph)(PPh3)]2 (1) and 1,2-cyclonona-
diene (2) in dichloromethane was stirred at room temperature
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2616 Organometallics, Vol. 27, No. 11, 2008
Bai et al.
Consistent with the solid state structure, the 31P{1H} NMR
spectrum shows a singlet at 24.5 ppm. The 1H NMR spectrum
shows two H signals of the allylic protons at ca. 4.7 and 5.9
Scheme 2
1
ppm.
Treatment of 1 with tert-butylallene (4) produces the allyl
complex PdI(η3-CH2CPhC(Ph)CHCMe3)(PPh3) (5), which was
isolated as a bright yellow solid in 84% yield. There are four
possible isomers for 5 because the CMe3 group can be in anti
or syn positions relative to the Ph group of the allyl ligand, and
the PPh3 ligand can be trans or cis to the allylic carbon having
the CMe3 group. The NMR data suggest that the isolated solid
contains two isomers in a ratio of 4.5:1. The 31P{1H} NMR
spectrum shows two singlets at 22.5 (major) and 23.1 (minor)
1
ppm. In the H NMR spectrum, the major isomer shows the
allylic proton signals at 3.63 (br s, 1 H, CH2), 3.70 (br m, 1 H,
CH2), and 5.68 (dd, J(PH) ) 6.6 Hz, J(HH) ) 1.8 Hz, CHCMe3)
ppm. The minor isomer shows the allylic proton signals at 4.06
(dd, J(PH) ) 11.0 Hz, J(HH) ) 2.4 Hz, 1 H, CH2), 4.68 (br dt,
J(PH) ) 7.2 Hz, J(HH) ) 2.1 Hz, CH2), and 4.87 (br m, 1 H,
CHCMe3) ppm.
for 30 min, the allyl complex PdI(η3-cyclo-CHC(Ph)CH-
(CH2)6)(PPh3) (3) was produced (Scheme 2). Complex 3 was
isolated as a pale yellow solid. Its structure has been confirmed
by an X-ray diffraction study. The molecular structure of 3 is
shown in Figure 1. The crystallographic details and selected
bond distances and angles are given in Tables 1 and 2,
respectively. The X-ray structure shown in Figure 1 clearly
reveals that the complex contains an allyl, a PPh3, and an iodide
ligand. In complex 3, the two terminal Pd-C(allyl) bond
distances (2.197(4) Å for Pd-C(1) and 2.182(4) Å for Pd-C(3))
are noticeably longer than that of the central Pd-C(2) bond
(2.147(4) Å). The Pd-C(1) bond is slightly longer than the
Pd-C(3) bond. Similar to what has been observed in complexes
such as PdI(CH2CHCH2)(PPh(t-Bu)(O-menthyl),32 PdBr(al-
lyl)(PR3),33 PdCl(CH2CHCH2)(PR3),34 and PdCl(CH2CMe-
CH2)(PR3),35 the Pd-C(allyl) bond trans to PR3 is usually longer
than the Pd-C(allyl) bond trans to halide, due to the difference
in trans influence.
The structures of the isomers can be assigned on the basis of
the magnitude of the P-H coupling constants. It has been noted
that palladium complexes of the type PdCl(η3-allyl)(PR3)36 and
Pd[(η3-allyl)(PR3)2]+ 37 have a J(Hanti-Ptrans) coupling constant
of 11–13 Hz, a J(Hsyn-Ptrans) coupling constant of 6–8 Hz, and
a J(Hanti or syn-Pcis) coupling constant of ca. 0 Hz. Thus the 1H
NMR data suggest that the major isomer of 5 can be assigned
to trans-5, in which the PPh3 ligand is trans to CHCMe3 and
CMe3 is anti to Ph, while the minor isomer can be assigned to
cis-5, in which the PPh3 ligand is cis to CHCMe3 and CMe3 is
also anti to Ph, as shown in Scheme 2.
The structure of trans-5 has been confirmed by X-ray
diffraction. As shown in Figure 2, the allylic ligand is bound to
Pd unsymmetrically with the more substituted terminal allylic
carbon (C(3)) trans to PPh3 and the CH2 group (C(1)) trans to
iodide. The Pd-C(1) and Pd-C(3) bond distances are 2.143(2)
and 2.2363(19) Å, respectively. The longer Pd-C(3) bond
compared with Pd-C(1) is expected because of the greater trans
influence of PPh3 compared with I.
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(c) Brumbaugh, J. S.; Whittle, R. R.; Parvez, M.; Sen, A. Organometallics
1990, 9, 1735.
The fact that trans-5 is more abundant than cis-5 in
solution is probably not surprising when the steric effect of
PPh3 is considered. It has been reported that solutions of
(34) See for example: (a) Zubiri, M. R.; Milton, H. L.; Slawin, A. M. Z.;
Woollins, J. D. Polyhedron 2004, 23, 865. (b) Milton, H. L.; Wheatley,
M. V.; Slawin, A. M. Z.; Woollins, J. D. Polyhedron 2004, 23, 3211. (c)
Boele, M. D. K.; Kamer, P. C. J.; Lutz, M.; Spek, A. L.; de Vries, J. G.;
van Leeuwen, P. W. N. M.; van Strijdonck, G. P. F. Chem.-Eur. J. 2004,
10, 6232. (d) Kumar, P. G. A.; Dotta, P.; Hermatschweiler, R.; Pregosin,
P. S.; Albinati, A.; Rizzato, S. Organometallics 2005, 24, 1306. (e) Milton,
H. L.; Wheatley, M. V.; Slawin, A. M. Z.; Woollins, J. D. Polyhedron
2004, 23, 2575. (f) Fuji, K.; Sakurai, M.; Kinoshita, T.; Kawabata, T.
Tetrahedron Lett. 1998, 39, 6323. (g) Leznoff, D. B.; Rancurel, C.; Sutter,
J. P.; Rettig, S. J.; Pink, M.; Kahn, O. Organometallics 1999, 18, 5097. (h)
Dinger, M. B.; Scott, M. J. Inorg. Chem. 2001, 40, 856. (i) Andrieu, J.;
Camus, J. M.; Dietz, J.; Richard, P.; Poli, R. Inorg. Chem. 2001, 40, 1597.
(j) Shi, W. J.; Xie, J. H.; Zhou, Q. L. Tetrahedron: Asymmetry 2005, 16,
705. (k) Marinetti, A.; Kruger, V.; Ricard, L. J. Organomet. Chem. 1997,
529, 465.
(35) See for example: (a) Albert, J.; Bosque, R.; Cadena, J. M.; Delgado,
S.; Granell, J.; Muller, G.; Ordinas, J. I.; Bardia, M. F.; Solans, X. Chem.-
Eur. J. 2002, 8, 2279. (b) Faller, J. W.; Blankenship, C.; Whitmore, B.;
Sena, S. Inorg. Chem. 1985, 24, 4483. (c) Albert, J.; Cadena, J. M.; Granell,
J.; Muller, G.; Ordinas, J. I.; .Panyella, D.; Puerta, C.; Sanudo, C.; Valerga,
P. Organometallics 1999, 18, 3511.
(29) See for example: (a) Groen, J. H.; Delis, J. G. P.; van Leeuwen,
P. W. N. M.; Vrieze, K. Organometallics 1997, 16, 68.
(30) Anderson, G. K. Organometallics 1983, 2, 665.
(31) Grushin, V. V.; Alper, H. Organometallics 1993, 12, 1890.
(32) Bayersdorfer, R.; Ganter, B.; Englert, U.; Keim, W.; Vogt, D. J.
Organomet. Chem. 1998, 522, 187.
(36) Kumar, P. G.; Dotta, P.; Hermatschweiler, R.; Pregosin, P. S.
Organometallics 2005, 24, 1306.
(33) Alberti, D.; Goddard, R.; Porschke, K. R. Organometallics 2005,
24, 3907.
(37) Malet, R.; Moreno-Manas, M.; Parella, T.; Pleixats, R. R. Orga-
nometallics 1995, 14, 2463.

Insertion Reactions of Allenes with Pd Aryl Complexes
Organometallics, Vol. 27, No. 11, 2008 2617
Figure 1. X-ray structure of compound 3 with thermal ellipsoids shown at the 40% probability level.
Table 1. Crystallographic Data and Structure Refinement Details for PdI(η3-cyclo-CHC(Ph)CH(CH)2)6)(PPh3) (3),
PdI(η3-(CH2CHC(Ph)CHCMe3)(PPh3) (trans-5), PdI(η3-CH2C(Ph)CH(SO2Ph))(PPh3) (cis-13), PdI(η3-MeCHC(Ph)CH(SO2Ph))PPh3 (cis-15),
PdI(η3-(CH2C(Ph)CH(P(O)(OEt)2))(PPh3) (trans-9), and PdI(η3-MeCHC(Ph)CH(P(O)(OEt)2))(PPh3) (cis-11)
3
trans-5
cis-13
cis-15
trans-9
cis-11
empirical formula
fw
cryst syst
space group
a, Å
b, Å
C33H34IPPd
694.87
monoclinic
P2(1)
8.6509(17)
19.449)4)
9.4379(19)
90
116.13(3)
90
1425.6(5)
2
C31H32IPPd
668.84
C33H28IO2PPdS
752.88
C34H30IO2PPdS
766.91
C31H33IO3P2Pd
748.81
C32H35IO3P2Pd
762.84
monoclinic
P2(1)/c
14.8326(11)
10.1125(7)
18.9106(14)
90
95.5750(10)
90
2823.1(4)
4
monoclinic
P2(1)/n
9.8674(8)
17.5903(14)
17.8699(14)
90
98.8060
90
3065.1(4)
4
monoclinic
P2(1)/c
15.5188(11)
17.4313(13)
23.4898(16)
90
91.454(2)
90
6452.2(8)
8
monoclinic
P2(1)/c
17.7153(12)
9.8948(6)
19.5425(13)
90
115.7450(10)
90
3085.6(3)
4
monoclinic
P2(1)/n
12.2084(13)
14.0521(15)
19.558(2)
90
105.207(2)
90
3237.7(6)
4
c, Å
R, deg
ꢀ, deg
γ, deg
V, Å3
Z
Dcalcd, g cm-3
1.619
1.810
1.574
1.824
1.632
1.761
1.604
1.701
1.612
1.735
1.565
1.655
µ, mm-1
2θ range, deg
no. of data collected
no. of unique data
no. of params/restraints
goodness of fit on F2
R1 (I > 2σ(I))
wR2 (I > 2σ(I))
peak/hole, e Å-3
2.62–25.00
12765
4795
325/1
1.009
0.0243
0.0422
0.740/-0.407
2.29–26.00
15844
5514
307/0
1.046
0.0197
0.0484
0.689/-0.371
2.23–27.00
17634
6653
364/0
1.006
0.0432
0.0939
1.049/-0.482
1.31–27.50
37681
14 342
723/0
1.001
0.0444
0.0855
0.838/-0.624
1.28–27.00
17661
6669
349/0
1.029
0.0440
0.1254
1.155/-0.838
1.78–27.00
18703
7057
353/5
0.914
0.0492
0.1173
0.955/-0.640
complexes such as PdCl(CH2C(Fc)CHCOFc)(PPh3),38 PdX(CH2-
CHCHPh)(PPh3) (X ) Cl, I),39 PdCl(CH2CHCHMe)(PCy2R)
(R ) Cy, 2-biphenyl),40 PdCl(CH2CHCMe(SiMe3)(PPh3),41 and
PdCl(CH2CHCHMe)(MOP)42 contain only the trans isomer in
which the PR3 is trans to the more substituted alyllic carbon.
Both trans and cis isomers were previously observed in
complexes PdCl(CH2CHCHPh)(PPh(1-naphthyl)(R)) (R ) Me,
i-Pr).43
The substitutents R in allyl complexes PdCl(CH2CHCHR)-
(PR′3) are usually at a position syn to the proton of the central
allyllic carbon. However, only isomers with the CMe3 group at
the anti position were observed for 5, probably due to the steric
effect of the Ph and CMe3 groups. We noted that
CH2dCdCHPh undergoes an insertion reaction with PdI(C6H3-
3,5-Me2)(bipy) in the presence of AgBF4 to give the allyl
complex [Pd(CH2C(C6H3-3,5-Me2)CHPh)(bipy)]BF4 as a 2:1
mixture of syn and anti isomers.21 Like complex 5, the C(O)Fc
group in complex PdCl(CH2C(Fc)CHC(O)Fc)(PPh3) is also in
the anti position.38
(38) Wu, R. J.; Liu, Y. H.; Yuan, H. Z.; Mao, X. A. J. Organomet.
Chem. 1996, 519, 237.
(39) Kawatsuhira, M.; Uozumi, Y.; Hayashi, T. Chem. Commun. 1998,
217.
Similar reaction occurred between 1 and CH2dCdCHCO2Et
(6), which has the electron-withdrawing group CO2Et, giving
the allyl complex PdI(η3-CH2CPhC(Ph)CHCO2Et)(PPh3) (7) as
a mixture of trans-7 and cis-7 in a ratio of 1.7:1 (Scheme 2).
The structures of the isomers can be readily assigned on the
basis of their NMR data. In the room-temperature 31P{1H} NMR
(40) Faller, J. W.; Sarantopoulos, N. Organometallics 2004, 23, 2179.
(41) Ohta, T.; Hosokawa, T.; Murahashi, S. I. Organometallics 1985,
4, 2080.
(42) Hayashi, T.; Iwamura, H.; Naito, M.; Matsumoto, Y.; Uozumi, Y.
J. Am. Chem. Soc. 1994, 116, 775.
(43) Grabulosa, A.; Muller, G.; Ordinas, J. I.; Mezzetti, A.; Maestro,
M. A.; Font-Bardia, M.; Solans, X. Organometallics 2005, 24, 4961.

2618 Organometallics, Vol. 27, No. 11, 2008
Bai et al.
Table 2. Selected Bond Distances (Å) and Angles (deg) for Complexes 3, trans-5, trans-9, cis-11, cis-13, and cis-15
spectrum, the signals of the major isomer trans-7 and the minor
isomer cis-7 were observed at 26.9 and 24.0 ppm, respectively.
In the room-temperature 1H NMR spectrum, the minor isomer
cis-7 exhibits sharp allylic signals at 4.91 ppm with a J(PH) of
9.9 Hz for anti-CH2, 5.08 ppm with a J(PH) of 6.0 Hz for syn-
CH2, and 4.68 ppm for CHCO2Et with unresolvable P-H
coupling, confirming that PPh3 is trans to CH2 and that CO2Et
is anti to Ph. The major isomer trans-7 is fluxional above 258
pm for CH2. It should be noted that two sharp 1H NMR signals
were observed for the allylic CH2 of cis-7 at room temperature,
indicating that the two protons are not exchanging with each
other. The observation that trans-7 is fluxional but cis-7 is not
at room temperature can be related to the trans effect of PPh3.
Exchange of CH2 in PdI(η3-CH2C(Ph)CHCO2Et)(PPh3) presum-
ably proceeds through a PdI(η1-CH2C(Ph)dCHCO2Et)(PPh3)
intermediate (eq 1). Due to the stronger trans influence of PPh3,
the opening of the substituted end of the allyl group in PdI(η3-
CH2C(Ph)CHCO2Et)(PPh3) to give PdI(η1-CH2C(Ph)dCHC-
O2Et)(PPh3) is more favorable for the trans isomer. It is noted
that the analogous allyl complex trans-PdCl(η3-CH2C-
(Ph)CHCMe3)(PPh3) (trans-5) is not fluxional at room temper-
ature. Probably, the CO2Et group of trans-7 can help to stabilize
the η1-allyl intermediate through π-conjugation, thus making
the fluxional process easier.
1
K, as indicated by the H NMR spectrum. Thus, in the room-
1
temperature H NMR spectrum, the allylic CHCO2Et proton
signal of trans-7 was observed at 5.39 ppm with a J(PH)
coupling constant of 8.5 Hz, while the 1H signals of the allylic
CH2 are too broad to be observed due to fast exchange of the
two protons. When the temperature is lowered below 258 K,
the signals of the CH2 group appeared. At 218 K, the 1H NMR
spectrum showed the allylic signals at 5.35 ppm with a J(PH)
coupling constant of 8.5 Hz for CHCO2Et and at 4.90 and 3.88
Figure 2. X-ray structure of compound trans-5 with thermal ellipsoids shown at the 40% probability level.

Insertion Reactions of Allenes with Pd Aryl Complexes
Organometallics, Vol. 27, No. 11, 2008 2619
Scheme 3
(1)
1,2-Allenyl diethylphosphonate 8 reacts with 1 to give the
allyl complex PdI(η3-CH2CPhC(Ph)CHP(O)(OEt)2)(PPh3) (9)
as a mixture of trans-9 and cis-9 in a ratio of 3.5:1 (Scheme
3). The presence of these isomers can be readily identified by
the 31P{1H} NMR spectrum, in which trans-9 shows two
doublets at 17.4 (P(O)(OEt)2) and 25.8 (PPh3) ppm with a J(PP)
coupling constant of 19.0 Hz. cis-9 shows two singlets at 19.0
(P(O)(OEt)2) and 25.3 (PPh3) ppm. The chemical shifts of the
palladium-bound PPh3 are similar to those of complexes 5 and
7, indicating that they have similar coordination spheres. In the
1H NMR spectrum, the allylic CHP signal of trans-9 was
observed at 4.96 ppm with a J(H-P(PPh3)) coupling constant
of 7.0 Hz, and that of cis-9 was observed at 4.16 ppm without
J(H-P(PPh3)) coupling. The 1H NMR data are consistent with
the structures in which the P(O)(OEt)2 substituent in 9 is anti
to the Ph group.
An X-ray diffraction study of trans-9 confirms that P(O)(O-
Et)2 is indeed anti to the Ph group in the complex (Figure 3).
trans-9 is structurally closely related to trans-5. Some differ-
ences in the structural features associated with Pd(η3-allyl) were
noted for trans-9 and trans-5 (Table 2). In particular, the
Pd-C(1) bond (2.162(4) Å) in trans-9 is slightly longer than
that in trans-5 (2.143(2) Å), while the Pd-C(3) bond (2.183(4)
Å) in trans-9 is appreciable shorter than that in trans-5
(2.2363(19) Å). As expected, the Pd-C(1) bond (2.162(4) Å)
is shorter than the Pd-C(3) bond (2.183(4) Å) in trans-9 due
to stronger trans influence of PPh3 compared with iodide.
However the difference is not as significant as that observed
for trans-5. The structural data may suggest that CH(P(O)(OEt)2
in trans-9 is bound to Pd more strongly than CHCMe3 in trans-
5. Apparently, the electron-withdrawing nature of P(O)(OEt)2
strengthens the bonding interaction between Pd and the allylic
carbon.
the major one. Thus one might expect that reaction of
CH2dCdCHSO2Ph (12) with 1 would give similar results.
Indeed, 12 readily reacts with 1 to produce a mixture of two
isomers of PdI(η3-CH2C(Ph)CHSO2Ph)(PPh3) (13). However,
the cis isomer cis-13 was found to be the major isomer (trans-
13:cis-13 ) 1:2.3). The isomer ratio remained unchanged after
standing the reaction mixture for more than 2 days. Therefore
the ratio must be related to relative thermodynamic stability.
The result implies that the -SO2Ph-substituted carbon ligand
could exert the largest trans influence among the carbon ligands
studied here with various substituents such as CO2Et and
P(O)(OEt)2) and destabilize the trans isomer that has a PPh3
ligand trans to it. Among the several X-ray structures of the
allyl complexes reported here, we indeed found that the
Pd-C(H)(SO2Ph) bonds are the shortest (Table 2).
The structures of the two isomers can be assigned on the
basis of their NMR data, as described previously for analogous
When the methyl-substituted allene MeCHdCdCHP(O)-
(OEt)2 (10) was allowed to react with 1, a mixture of two
isomers of the palladium allyl complex PdI(η3-MeCHC(Ph)-
CHP(O)(OEt)2)(PPh3) (11) was obtained as one might expect
(Scheme 3). However, different from the previous cases, the
major isomer is the cis isomer cis-11 rather than the trans isomer
trans-11 (trans-11/cis-11 ) 1:4.3). It appears that the Me group
decreases the stability of the trans isomer. The presence of the
methyl substituent introduces a strong repulsive interaction with
the PPh3 ligand in the trans isomer (not in the cis isomer),
weakens the Pd-C(H)(Me) bonding interaction, and therefore
decreases the stability.
The structure of cis-11 has been determined by X-ray
diffraction. As revealed by the structure shown in Figure 4, the
P(O)(OEt)2 substituent is anti to the Ph, while Me is syn to Ph.
The allyl ligand is unsymmetrically bound to Pd with the
Pd-C(1) bond (2.263(5) Å) being significantly longer than the
Pd-C(3) bond (2.085(5) Å). A large difference in the Pd-C
bond distances can be related to the fact that PPh3 is a stronger
trans influence ligand than iodide and that P(O)(OEt)2 is
electron-withdrawing, while Me is electron-donating.
In the insertion reactions of 1 with CH2dCdCHR (R )
CMe3, CO2Et, P(O)(OEt)2), the reaction products are a mixture
of two isomeric allyl complexes, with the trans isomer being
Figure 3. X-ray structure of compound trans-9 with thermal
ellipsoids shown at the 30% probability level.

2620 Organometallics, Vol. 27, No. 11, 2008
Bai et al.
Figure 6. X-ray structure of compound cis-15 with thermal
ellipsoids shown at the 30% probability level.
Figure 4. X-ray structure of compound cis-11 with thermal
ellipsoids shown at the 30% probability level.
The structure of cis-15 has also been determined by an X-ray
diffraction study, which indicates that the SO2Ph group is anti
while Me is syn to the Ph group (Figure 6). The structural
features associated with the Pd(η3-allyl) moiety in cis-15 are
very similar to those in PdI(η3-MeCHC(Ph)CHP(O)(OE-
t)2)(PPh3) (cis-11). The only noticeable differences are that the
Pd-C(1) bond distance of cis-15 (2.314(5) Å) is appreciably
longer than that of cis-11 (2.263(5) Å), while the Pd-C(3) bond
distance of cis-15 (2.073(5) Å) is slightly shorter than that of
cis-11 (2.085(5) Å), suggesting that SO2Ph is more electron-
withdrawing than P(O)(OEt)2. The solid state structure is fully
supported by the solution NMR data.
Reactions of Allenes with [PdPhI(dppe)] in the
Presence of TlPF6. To model insertion reactions involving Pd
species containing two phosphine ligands, we have carried out
reactions of allenes with PdI(Ph)(dppe) (16). In catalytic
reactions using Pd/PPh3 as the catalyst, PdI(Ph)(PPh3)2 could
be generated. However, PdI(Ph)(dppe) instead of PdI(Ph)(PPh3)2
was used in our study, because we want to minimize the chance
of phosphine dissociation to give monophosphine species. The
starting material PdI(Ph)(dppe) was prepared by reaction of
Pd(PPh3)4 with dppe followed by PhI.44
It is generally believed that insertion reactions of Pd(II)
complexes with unsaturated substrates usually proceed through
four-coordinate species, although reactions involving five-
coordinated species have also been proposed occasionally in
the literature. Thus, without dissociation of phosphine, PdI(Ph-
)(dppe) may undergo insertion reactions with allenes through
four-coordinate intermediates [PdPh(dppe)(allene)]+ or five-
coordinate intermediates PdI(Ph)(dppe)(allene).
To test if facile insertion reactions can occur through five-
coordinate intermediates PdI(Ph)(dppe)(allene), we have moni-
tored by NMR the reactions of PdI(Ph)(dppe) with allenes
CH2dCdCHSO2Ph and MeCHdCdCHSO2Ph. As indicated
by in situ 31P{1H} NMR, no appreciable reactions occurred after
a 1:2 (molar ratio) mixture of PdI(Ph)(dppe) and an allene
(CH2dCdCHSO2Ph or MeCH2dCdCHSO2Ph) in benzene or
Figure 5. X-ray structure of compound cis-13 with thermal
ellipsoids shown at the 30% probability level.
complexes. In addition, the structure of cis-13 has also been
confirmed by an X-ray diffraction study (Figure 5). Overall,
the structural features associated with the Pd(η3-allyl) moiety
in cis-13 are very similar to those of the analogous complex
cis-11, except that the Pd-C(1) bond (2.218(5) Å) in cis-13 is
slightly shorter than that (2.263(5) Å) in cis-11.
The methyl-substituted allene MeCH2dCdCHSO2Ph (14)
undergoes insertion with 1 to give only the cis isomer (cis-15)
of the allyl complex PdI(η3-MeCHC(Ph)CHSO2Ph)(PPh3). As
mentioned previously, a mixture of cis and trans isomers (in a
ratio of 2.3:1) was observed for the analogous complex PdI(η3-
CH2CPhC(Ph)CHSO2Ph)(PPh3) (13). The result is consistent
with the stabilizing effect of a methyl group for the cis isomer
noted for allyl complexes with a P(O)(OEt)2 substituent (see
discussion above).
(44) Owen, G. R.; Vilar, R.; White, A. J. P.; Williams, D. J. Organo-
metallics 2003, 22, 4511.

Insertion Reactions of Allenes with Pd Aryl Complexes
Organometallics, Vol. 27, No. 11, 2008 2621
Scheme 4
Scheme 5
complexes were not observed in our experiments in this study
for all the allenes used in this study.
In order to examine the relative barriers for the formation of
allyl complexes, which were observed in the present systems,
and vinyl complexes, a computational study was carried out.
In the computational study, we used the model complex
PdI(Ph)(η2-MeCHdCdCHSO2H)(PH3) (22), which is related
to the reaction intermediate in the reaction of [PdI(Ph)(PPh3)]2
with MeCHdCdCHSO2Ph. Scheme 6 shows four structural
isomers of PdI(Ph)(η2-MeCHdCdCHSO2H)(PH3) (22) that are
possible precursor complexes for allene insertion. In both the
precursor complexes 22A and 22B, the Ph ligand is trans to I
and the allene ligand is trans to PH3. In 22A, the allene is bound
to Pd via the CdC double bond having an –SO2H substituent.
In 22B, the allene is bound to Pd via the CdC double bond
having a methyl substitutent. In both the precursor complexes
22C and 22D, the Ph ligand is trans to PH3 and the allene ligand
is trans to I. In 22C, the allene is bound to Pd via the CdC
double bond having an –SO2H substituent. In 22D, the allene
is bound to Pd via the CdC double bond having a methyl
substituent.
dichloromethane was stood at room temperature for 12 h. The
observation suggests that insertion reactions through five-
coordinate intermediates PdI(Ph)(dppe)(allene) cannot occur
readily.
In contrast, facile insertion reactions were observed when the
reactions were carried out in the presence of TlPF6, which can
help to remove the iodide to generate [Pd(Ph)(dppe)]+ and
[PdPh(dppe)(allene)]+ subsequently in situ. Treatment of PdI(Ph-
)(dppe) (16) with CH2dCdCHR (R ) CMe3, CO2Et, COPh,
SO2Ph) in dichloromethane in the presence of TlPF6 rapidly
produced the cationic allyl complexes [Pd(η3-CH2C(Ph)-
CHR)(dppe)]PF6 (17PF6, R ) CMe3; 18PF6, R ) CO2Et;
19PF6, R ) COPh; 20PF6, R ) SO2Ph). Reaction of 16 with
MeCHdCdCHSO2Ph in the presence of TlPF6 produced the
analogous allyl complex [Pd(η3-MeCHC(Ph)CHSO2Ph)(dppe)]-
PF6 (21PF6) (Schemes 4 and 5). The complexes can be
converted to the corresponding BPh4 salts on treatment with
NaBPh4.
The structures of these allyl complexes can be deduced on
the basis of their NMR data. Consistent with the unsymmetrical
nature of the structures shown in Schemes 4 and 5, the 31P{1H}
NMR spectrum of each of the allyl complexes exhibits two
doublet signals. The presence of an η3-allyl ligand and the
stereochemistry of the allyl ligand are clearly indicated by the
1H NMR data. For example, the 1H NMR spectrum of 17BPh4
displayed two allylic proton signals of CH2 at 4.15 and 4.49
ppm and that of CHCMe3 at 5.58 ppm with a J(PH) coupling
constant of 5.8 Hz. The magnitude of the J(PH) coupling
constant suggests that the CMe3 group is anti to the Ph group.
The room-temperature 1H NMR spectrum of [Pd(η3-
CH2C(Ph)CHCO2Et)(dppe)]BPh4 (18BPh4) shows the signal of
the allylic proton of CHCO2Et at 5.41 ppm with a J(PH) coupling
constant of 6.8 Hz, again suggesting that the allylic proton is syn
to the Ph group and that the CO2Et group is anti to the Ph group.
At room temperature, only one signal at 5.01 ppm was observed
for the two CH2 protons of 18BPh4, suggesting that the two protons
are exchanging rapidly. Similarly, the analogous allyl complex
[Pd(η3-CH2C(Ph)CHCO2Et)(dppe)]BPh4 (19BPh4) displayed the
CHCOPh proton signal at 6.32 ppm and the CH2 signal at 5.19
ppm. The NMR data of 20 and 21 are in agreement with the
structures shown in Scheme 5.
The four precursor complexes have comparable stabilities,
with 22A being the most stable one. Since a coordinated allene
can switch the coordinated CdC double bond rapidly, it is
reasonable to assume that the four precursor complexes can all
participate in the insertion reaction. Figure 7 shows the relevant
energy profiles for the eight possible reaction pathways of the
insertion reactions from the four precursor complexes. Each
precursor complex gives rise to two possible pathways, one
leading to the formation of an allyl complex and the other
leading to the formation of a vinyl complex.
The calculation results show that the reaction pathway from
22A to give first the intermediate 23A, then trans-24, and finally
the allyl complex cis-24 is both thermodynamically and kineti-
cally the most favorable among all the reaction pathways
studied. The allyl complex cis-24 is a model complex for the
product cis-15 observed in the reaction of [PdI(Ph)(PPh3)]2 with
MeCHdCdCHSO2Ph (see Scheme 3). The calculation results
are clearly consistent with the experimental observation dis-
cussed above.
The insertion reactions from the precursor complexes 22A
and 22C, whose coordinated CdC double bond has an –SO2H
substituent, give the allyl complexes favorably. However, the
insertion reactions from the precursor complexes 22B and 22D,
whose coordinated CdC double bond has a methyl substituent,
give the vinyl complexes kinetically favorably. In an early study
on allene insertion into a metal-hydride bond, we have
established that the migratory hydride acts as a nucleophile,
attacking one of the two carbons in the η2-coordinated CdC
Theoretical Study. In the discussion above, we have
presented our experimental results of insertion reactions of
[PdIPh(PR3)]2 and PdI(Ph)(dppe) with a series of allenes
containing either an electron-withdrawing or an electron-
donating group. The results clearly show that insertion reactions
of allenes involving both neutral species PdI(Ph)(PR3)(allene)
and the cationic species [Pd(Ph)(dppe)(allene)]+ always give
allyl complexes. The possible insertion products of vinyl

2622 Organometallics, Vol. 27, No. 11, 2008
Bai et al.
Scheme 6
bond.45 The preferred reaction pathways observed here can also
be understood when we also consider the migratory phenyl
ligand acting as a nucleophile. It is known that the central carbon
of allene is electron-deficient. The –SO2H substituent is an
electron-withdrawing group, while methyl is an electron-
donating group. Therefore, the inductive effect of the SO2H at
the coordinated CdC π bond and the methyl group at the
noncoordinated CdC π bond will make the central carbon of
the allene ligand in 22A and 22C even more electron-deficient
than the -SO2H-substituted carbon when the π-electron density
of the coordinated CdC π bond is considered. As a result, the
phenyl ligand migrates preferentially to the central carbon,
leading to the formation of an allyl complex. In 22B and 22D,
in contrast, the central carbon of the allene ligand may become
more electron-rich than the methyl-substituted carbon when the
π electron density of the coordinated CdC π bond is considered,
due to the inductive effect of the methyl at the coordinated CdC
π bond and the SO2H group at the noncoordinated CdC π bond.
Therefore, the phenyl ligand migrates preferentially to the
methyl-substituted carbon to give a vinyl complex if the insertion
reaction occurs in the precursor complex 22B or 22D.
It is noted that reaction pathways involving 22C and 22D
have a higher barrier than the corresponding pathways involving
22A and 22B; that is, TSC and TSC′ are higher in energy than
TSA and TSA′, respectively, and TSD and TSD′ are higher in
energy than TSB and TSB′, respectively. It is likely that the
trans arrangement of the iodide ligand with respect to the allene
ligand in 22C and 22D constitutes a push–pull scenario that
enhances the metal(d)-to-allene(π*) back-bonding interactions,
increases the π electron density of the two carbons in the
coordinated CdC bond, and thus increases the phenyl migration
energy barriers. Earlier theoretical studies have already shown
that olefin insertion into an M-R bond is kinetically and
thermodynamically less favorable when a metal(d)-to-olefin(π*)
back-bonding interaction is present.46
In the calculations, we used PH3 as a model phosphine for
PPh3 employed in the experiments. It is necessary to examine
whether the simple model is sufficient. Employing PPh3 as the
phosphine ligand, we optimized the species corresponding to
22A, TSA′, TSA, trans-24, and cis-24 in Figure 7. In the PH3-
based models, the relative electronic energies of 22A, TSA′,
TSA, trans-24, and cis-24 are 0.0, 14.7, 6.7, -39.7, and -45.4
kcal/mol, respectively. With PPh3 used as the phosphine ligand,
the relative electronic energies are, 0.0, 17.8, 9.8, -40.3, and
-45.3 kcal/mol, respectively. The barriers increase slightly from
the simple models to the realistic models. The additional
calculations based on the realistic PPh3 ligand indicate that the
conclusions derived from the simple model calculations are
valid. The results are understandable because the steric and
electronic effects of the PPh3 ligands are similar for the reactants
and the transition states.
Conclusion
We have studied the insertion reactions of [PdI(Ph)(PPh3)]2
and PhI(Pd)(dppe) with allenes containing various substituents.
While PdI(Ph)(dppe) was found to be unreactive toward allenes
such as CH2dCdCHSO2Ph and MeCHdCdCHSO2Ph at room
temperature, [PdI(Ph)(PPh3)]2 and PhI(Pd)(dppe)/TlPF6 readily
react with allenes to give η3-allyl complexes, presumably
through the intermediates PdI(Ph)(PPh3)(allene) and [PdI(Ph-
)(dppe)(allene)]+, respectively. The mechanistically possible
insertion products of vinyl complexes were never observed in
our experiments in this study. The substituents of allenes appear
to have no effect on the reaction pathways, at least for the allenes
used in this study. A computational study shows that formation
of allyl complex PdI(η3-MeCHC(Ph)CHSO2H)(PH3) from
PdI(Ph)(MeCHdCdCHSO2H)(PH3) is both thermodynamically
and kinetically favored.
Clearly, the regioselectivity uncovered from the calculation
results is a result of both the -SO2H and -Me substituents
being capable of polarizing the π electron density in the
coordinated CdC π bond of the allene ligand, making one
carbon of the coordinated CdC bond more π-electron-deficient
and the other more π-electron-rich, and thus giving rise to the
discrimination against the π-electron-rich carbon to which the
phenyl ligand migrates. TSA′ is higher in energy than TSB′,
but TSA is lower than TSB (Figure 7a). TSC′ is higher in
energy than TSD′, but TSC and TSD are comparable in stability
(Figure 7b). These results indicate that the -SO2H substituent
of the coordinated CdC π bond has a greater polarizing power
than the -Me substituent. The lower barrier for the formation
of an allyl complex from 22A via TSA compared with that for
the formation of a vinyl complex from 22B via TSB is
apparently related to the difference in the π electron density of
the cabron atom to which the Ph migrates.
Experimental Section
All manipulations were carried out under an argon atmosphere
using standard Schlenk techniques, unless otherwise stated. Solvents
were distilled under nitrogen from sodium benzophenone (hexane,
ether, THF) or calcium hydride (CH2Cl2). The starting materials
[PdI(Ph)(PPh3)]2,31 PdI(Ph)(dppe),44 CH2dCdCHR (R ) CMe3,
CO2Et, P(O)(OEt)2, and SO2Ph), and MeCHdCdCHR (R )
P(O)(OEt)2 and SO2Ph)47 were prepared following the procedures
described in the literature. Microanalyses were performed by MHW
Laboratory (Phoenix, AZ) or collected on a Vario EL III analyzer
at Shanghai Institute of Organic Chemistry. 1H, 13C{1H}, and
31P{1H} spectra were collected on a Varian Mercury spectrometer
(300 MHz) or a Bruker spectrometer (300, 500 MHz). 1H and 13
C
chemical shifts are relative to TMS, and 31P chemical shifts are
relative to 85% H3PO4.
PdI(η3-cyclo-CHC(Ph)CH(CH2)6)(PPh3) (3). A solution of
[PdI(Ph)(PPh3)]2 (151 mg, 0.130 mmol) and 1,2-cyclononadiene
(45) Bai, T.; Zhu, J.; Xue, P.; Sung, H H.-Y.; Williams, I. D.; Ma, S.;
Lin, Z.; Jia, G. Organometallics 2007, 26, 5581.
(47) (a) Brandsma, L.; Verkruijsse, H. D. Studies in Organic Chemistry
8, Synthesis of Acetylene, Allenes and Cumulenes; Elsevier: Amsterdam,
1981. (b) Trost, B. M.; Pinkerton, A. B.; Seidel, M. J. Am. Chem. Soc.
2001, 123, 12466.
(46) (a) Margl, P.; Deng, L.; Ziegler, T. J. Am. Chem. Soc. 1998, 120,
5517. (b) Niu, S.; Hall, M. B. Chem. ReV. 2000, 100, 353.

Insertion Reactions of Allenes with Pd Aryl Complexes
Organometallics, Vol. 27, No. 11, 2008 2623
Figure 7. Energy profiles calculated for the insertion reactions of PdI(Ph)(PH3)(η2-MeCHdCdCHSO2H). The relative free energies and
electronic energies (in parentheses) are given in kcal/mol.

2624 Organometallics, Vol. 27, No. 11, 2008
Bai et al.
(0.040 mL, 0.32 mmol) in CH2Cl2 (8 mL) was stirred at room
temperature for 30 min. The reaction mixture was concentrated to
dryness. The residue was washed with diethyl ether (3 mL × 3)
and dried under vacuum to afford a pale yellow solid. Yield: 0.14 g,
filtration, washed with ether (3 mL), and dried under vacuum. Yield:
41 mg, 63%. NMR data show that the product is an isomeric
mixture of trans-9 and cis-9 in a ratio of 3.5:1. 1H NMR (500 MHz,
CDCl3) of trans-9 (major isomer): δ 1.22 (br s, 3 H, CH2CH3),
1.32 (br s, 1.32, 3 H, CH2CH3), 4.16 (br s, 2 H, CH2CH3), 3.88 (br
s, 1 H, CH2), 4.26 (br s, 1 H, CH2CH3), 4.35 (br, 1 H, CH2CH3),
4.52 (br s, 1 H, CH2), 4.96 (dd, J(PH) ) 7.0, 5.5 Hz, CHP),
7.22–7.54 (m, 20 H, PPh, Ph, mixed with those of cis-9). 1H NMR
(500 MHz, CDCl3) of cis-9 (minor isomer): δ 0.91 (t, J(HH) )
7.1 Hz, 3 H, CH2CH3), 1.13 (t, J(HH) ) 7.1 Hz, 3 H, CH2CH3),
3.62 (m, 1 H, CH2CH3), 3.76 (m, 1 H, CH2CH3), 3.86 (m, 2 H,
CH2CH3), 4.16 (dd, J(PH) ) 5.2 Hz, J(HH) ) 2.5 Hz, CHP), 4.59
(d, J(PH) ) 10.0 Hz, 1 H, dCH2), 5.05 (dd, J(PH) ) 6.2, J(HH)
) 2.5 Hz, 1 H, CH2), 7.12–7.53 (m, 20 H, PPh, Ph, mixed with
those of trans-9). 31P{1H} NMR (121.5 MHz, CDCl3): δ 17.4 (d,
J(PP) ) 19.0 Hz (trans-9)), 19.0 (s, (cis-9)), 25.3 (s, (cis-9)), 25.8
(d, J(PP) ) 19.0 Hz (trans-9)). Anal. Calcd for C31H33IO3P2Pd: C,
49.72; H, 4.44. Found: C, 49.78; H, 4.72.
1
76%. H NMR (300 MHz, C6D6, 298 K): δ 1.08–1.36 (m, 5 H,
CH2), 1.38–1.54 (m, 1 H, CH2), 1.54–1.80 (m, 3 H, CH2), 1.82–2.04
(m, 1 H, CH2), 2.22–2.46 (m, 1 H, CH2), 3.18–3.38 (m, 1 H, CH2),
4.58–4.78 (m, 1 H, CH), 5.78–5.98 (m, 1 H, CH), 7.00–7.26 (m,
14 H, m,p-PhP, Ph), 7.78–8.02 (m, 6 H, o-PhP). 31P{1H} NMR
(121.5 MHz, CDCl3, 298 K): δ 24.5 (s). Anal. Calcd for
C33H34IPPd · 0.25CH2Cl2: C, 55.76; H, 4.86. Found: C, 55.92; H,
5.06.
PdI(η3-CH2C(Ph)CHCMe3)(PPh3) (5). A suspension of [PdI-
(Ph)(PPh3)]2 (233 mg, 0.20 mmol) and tert-butylallene (0.040 g,
0.42 mmol) in benzene (10 mL) and CH2Cl2 (5 mL) was stirred at
room temperature for 2 h to give a clear solution. The mixture was
concentrated to dryness under vacuum to give a yellow oil, to which
was added diethyl ether (4 mL) to give a precipitate. This precipitate
was collected by filtration and washed with ether (2 mL × 2) and
dried under vacuum to give a bright yellow solid. Yield: 0.23 g,
84%. NMR data show that the product is a mixture of trans-5 and
PdI(η3-MeCHC(Ph)CHP(O)(OEt)2)(PPh3) (11). A mixture of
[PdI(Ph)(PPh3)]2 (203 mg, 0.177 mmol) and 1,2-butadiethyl di-
enylphosphonate (81 mg, 0.426 mmol) in dichloromethane (10 mL)
was stirred at room temperature for 10 h to give a clear yellow
solution. The resulting solution was concentrated to dryness under
vacuum to give an oily residue, which was treated with n-hexane
(6 mL × 2) to give a yellow precipitate. The solid was collected
by filtration, washed with n-hexane (6 mL), and dried under
vacuum. The NMR data show that the product is an isomeric
mixture of trans-11 and cis-11 in a ratio of 1:4, Total yield: 186
mg, 70%. 1H NMR (500 MHz, CDCl3) of trans-9 (minor isomer):
δ 1.22 (t, J(HH) ) 7.0 Hz, 3 H, CH2CH3), 1.29 (t, J(HH) ) 7.0
Hz, 3 H, CH2CH3), 1.67 (m, 3 H, CHCH3), 3.5–4.08 (m, 3 H,
CHCH3 and 2 H of CH2CH3), 4.62 (dd, J(PH) ) 7.8, 5.3 Hz, 1 H,
CHP), 7.20–7.82 (m, 20 H, PPh, Ph, mixed with those of cis-11).
1H NMR (500 MHz, CDCl3) of cis-9 (major isomer): δ 0.88 (t,
J(HH) ) 7.1 Hz, 3 H, CH2CH3), 1.14 (t, J(HH) ) 7.1 Hz, 3 H,
CH2CH3), 2.16 (dd, J(PH) ) 7.9 Hz, J(HH) ) 6.8 Hz, CHCH3),
3.54 (m, 1 H, CH2CH3), 3.67 (d, J(PH) ) 4.9 Hz, 1 H, CHP), 3.84
(m, 2 H, CH2CH3), 5.42–5.48 (m, 2 H, CHCH3), 7.20–7.82 (m, 20
H, PPh, Ph, mixed with those of trans-11). 31P{1H} NMR (121.5
MHz, CDCl3): δ 17.0 (d, J(PP) ) 18.4 Hz, trans-11), 19.5 (s, cis-
11), 27.9 (s, cis-11), 30.0 (d, J(PP) ) 18.4 Hz, trans-11). Anal.
Calcd for C32H35IO3P2Pd: C, 50.38; H, 4.62. Found: C, 50.12; H,
4.61.
1
cis-5 in a ratio of 4.5:1. H NMR (300 MHz, CD2Cl2, 298 K) of
trans-5 (major isomer): δ 1.26 (s, 9 H, CH3), 3.63 (br s, 1 H, CH2),
3.70 (br m, 1 H, CH2), 5.68 (dd, J(PH) ) 6.6 Hz, J(HH) ) 1.8 Hz,
1 H, CH), 7.12–7.58 (m, 20 H, PPh, Ph, mixed with those of cis-
1
5). H NMR (300 MHz, CD2Cl2, 298 K) of cis-5 (minor isomer):
δ 0.82 (s, 9 H, CH3), 4.06 (dd, J(PH) ) 11.0 Hz, J(HH) ) 2.4 Hz,
CH2), 4.68 (br d t, J(PH) ) 7.2 Hz, J(HH) ) 2.1 Hz, CH2)), 4.87
(br s, 1 H, CH), 7.12–7.58 (m, 20 H, PPh, Ph, mixed with those of
trans-5). 1H{31P} NMR (300 MHz, CD2Cl2, 298 K) of trans-5: δ
1.26 (s, 9 H, CH3), 3.62 (d, J(HH) ) 1.9 Hz, 1 H, CH2), 3.70 (t,
J(HH) ) 1.9 Hz, 1 H, CH2), 5.68 (d, J(HH) ) 1.9 Hz, 1 H, CH),
7.12–7.58 (m, 20 H, PPh, Ph, mixed with those of cis-5). 1H{31P}
NMR (300 MHz, CD2Cl2, 298 K) of cis-5: δ 0.83 (s, 9 H, CH3),
4.07 (d, J(HH) ) 2.3 Hz, 1 H, CH2), 4.67 (t, J(HH) ) 2.3,1.9 Hz,
1 H, CH2), 4.87 (d, J(HH) ) 1.9 Hz, 1 H, CH), 7.12–7.58 (m, 20
H, PPh, 2-Ph, mixed with those of trans-5). 31P{1H} NMR (121.5
MHz, CD2Cl2, 298 K): δ 22.5 (s, trans-5), 23.1 (s, cis-5). Anal.
Calcd for C31H32IPPd: C, 55.66; H, 4.82. Found: C, 55.71; H, 5.07.
PdI(η3-CH2C(Ph)CHCO2Et)(PPh3) (7). A suspension of [PdI-
(Ph)(PPh3)]2 (225 mg, 0.200 mmol) and ethyl 2,3-butadienoate
(0.050 g, 0.44 mmol) in benzene (10 mL) was stirred at room
temperature for 2 h to give a clear orange solution. The mixture
was concentrated to dryness, and diethyl ether (2 mL) was added
to give a yellow solid. The solid was collected by filtration, washed
with hexane (2 mL × 3), and dried under vacuum. Yield: 0.22 g,
80%. The NMR data show that the product is an isomeric mixture
of trans-7 and cis-7 in a ratio of 1.7:1. 1H NMR (300 MHz, CD2Cl2,
218 K) of trans-7 (major isomer): δ 1.20 (t, J(HH) ) 7.1 Hz, 3 H,
CH2CH3), 3.88 (br s, 1 H, CH2), 3.94–4.22 (m, 2 H, CH2CH3),
4.90 (br s, 1 H, CH2), 5.35 (d, J(PH) ) 8.5 Hz, 1 H, CH), 7.04–7.50
(m, 20 H, PPh, Ph, mixed with those of cis-7). 1H NMR (300 MHz,
CD2Cl2, 218 K) of cis-7 (minor isomer): δ 0.64 (t, J(HH) ) 7.1
Hz, 3 H, CH2CH3), 3.20–3.38 (m, 1 H, CH2CH3), 3.58–3.76 (m, 1
H, CH2CH3), 4.63 (br s, 1 H, CHCO2Et), 4.85 (d, J(PH) ) 9.9 Hz,
1 H, CH2), 5.07 (br d, J(PH) ) 5.7 Hz, 1 H, CH2), 7.04–7.50 (m,
20 H, PPh, Ph, mixed with those of cis-7). 31P{1H} NMR (121.5
MHz, CD2Cl2, 218 K): δ 26.6 (s, trans-7), 24.0 (s, cis-7). Anal.
Calcd for C30H28IO2PPd: C, 52.61; H, 4.12. Found: C, 52.74; H,
4.30.
PdI(η3-CH2C(Ph)CHSO2Ph)(PPh3) (13). A mixture of [PdI(Ph)-
(PPh3)]2 (500 mg, 0.435 mmol) and 1,2-propadienylsulfonylbenzene
(200 mg, 1.11 mmol) in dichloromethane (30 mL) was stirred at
room temperature for 3 h to give a clear yellow solution. The
resulting solution was concentrated to dryness under vacuum to
give an oily residue, which was treated with ether (25 mL × 2) to
give a yellow precipitate. The solid was collected by filtration,
washed with n-hexane (25 mL), and dried under vacuum. Yield:
590 mg, 90%. The NMR data show that the product is an isomeric
1
mixture of trans-13 and cis-13 in a ratio of 1:2.3. H NMR (300
MHz, CDCl3) of trans-13 (minor isomer): δ 3.97 (s, 1 H, CH2),
5.03 (s, 1 H, CH2), 5.93 (dd, 1 H, J(PH) ) 7.2 Hz, J(HH) ) 1.8
Hz, 1 H, CH), 7.92–6.92 (m, 25 H, Ph and PPh, mixed with those
1
cis-13). H NMR (300 MHz, CDCl3) of cis-13 (major isomer): δ
4.96 (d, J(HH) ) 1.5 Hz, 1 H, CH), 5.16 (dt, 1 H, J(PH) ) 9.3
Hz, J(HH) ) 1.8 Hz, 1 H, CH2), 5.30 (dd, J(PH) ) 8.4 Hz, J(HH)
) 1.8 Hz, 1 H, CH2), 7.92–6.92 (m, 25 H, Ph and PPh3, mixed
with those of trans-13). 31P{1H} NMR (121.5 MHz, CDCl3): 24.7
(s, trans-4a), 27.0 (s, cis-4a). Anal. Calcd for C33H28IO2PPdS: C,
52.64; H, 3.75. Found: C, 52.53; H, 3.82.
PdI(η3-CH2C(Ph)CHP(O)(OEt)2)(PPh3) (9). A mixture of
[PdI(Ph)(PPh3)]2 (50 mg, 0.0435 mmol) and 1,2-propadiethyl
dienylphosphonate (19 mg, 0.107 mmol) in dichloromethane (2 mL)
was stirred at room temperature for 8 h to give a clear yellow
solution. The resulting solution was concentrated to dryness under
vacuum to give an oily residue, which was treated with ether (3
mL × 2) to give a yellow precipitate. The solid was collected by
PdI(η3-MeCHC(Ph)CHSO2Ph)(PPh3) (cis-15). A mixture of
[PdI(Ph)(PPh3)]2 (2.00 g, 1.746 mmol) and 1,2-butadienylsulfo-
nylbenzene (712 mg, 3.67 mmol) in dichloromethane (60 mL) was
stirred at room temperature for 8 h to give a clear yellow solution.

Insertion Reactions of Allenes with Pd Aryl Complexes
Organometallics, Vol. 27, No. 11, 2008 2625
The resulting solution was concentrated to dryness under vacuum.
The oily residue was treated with n-hexane (35 mL × 2) to give a
yellow precipitate. The solid was collected by filtration, washed
with n-hexane (35 mL), and dried under vacuum. Yield: 2.628 g,
solvents, CH2Cl2 (5 mL) was added. The mixture was filtered
through a pad of Celite, and the Celite was washed with CH2Cl2
(1 mL) and filtered. The combined filtrates were concentrated to
dryness. The residue was washed with hexane (2 mL × 2) and a
mixture of hexane/ether (5 mL, 2/3, v/v) and then dried under
vacuum to give an orange solid. Yield: 0.22 g, 96%. 1H NMR (300
MHz, CD2Cl2, 298 K): δ 0.85 (t, J(HH) ) 7.1 Hz, CH2CH3, OEt),
2.42–2.68 (m, 4 H, PCH2), 3.50–3.78 (br, 2 H, CH2CH3), 4.98 (d,
J(PH) ) 6.6 Hz, 2 H, CH2), 5.37 (d, J(PH) ) 6.8 Hz, 1 H, CH),
6.93 (d, J(HH) ) 7.6 Hz, 2 H, 2-Ph), 7.21 (dd, J(HH) ) 7.6, 7.7
Hz, Ph), 7.24–7.66 (m, 20 H, PPh). 31P{1H} NMR (121.5 MHz,
CD2Cl2, 298 K): δ –143.2 (septet, J(PF) ) 713 Hz, PF6), 53.9 (d,
J(PP) ) 37.9 Hz), 57.8 (d, J(PP) ) 37.9 Hz).
1
97%. H NMR (300 MHz, CDCl3): δ 2.21 (dd, 3 H, J(PH) ) 7.8
Hz, J(HH) ) 6.7 Hz, CH-CH3), 4.59 (s, 1 H, CHSO2Ph), 6.19 (dt,
J(PH) ) 8.4 Hz, J(HH) ) 6.7 Hz, 1 H, CH-CH3), 7.74–6.87 (m,
25 H, Ph and PPh3). 13C{1H}NMR (75.47 MHz, CDCl3): δ 17.1
(d, J(PC) ) 4.0 Hz, CH3), 53.4 (s, allylic-C), 98.3 (d, J(PC) )
25.9 Hz, allylic-C), 83.1 (d, J(PC) ) 4.6 Hz, allylic-C), 126.9–142.53
(m, Ph and PPh3). 31P{1H} NMR (121.5 MHz, CDCl3): δ 29.8 (s).
Anal. Calcd for C34H30IO2PPdS: C, 53.24; H, 3.94. Found: C, 50.16;
H, 4.08. As indicated by 1H NMR, the sample contains dichlo-
romethane. Anal. Calcd for C34H30IO2PPdS · 0.75CH2Cl2: C, 50.23;
H, 3.82.
[Pd(η3-CH2C(Ph)CHCO2Et)(dppe)]BPh4 (18BPh4). To a solu-
tion of [Pd(η3-CH2C(Ph)CHCOOEt)(dppe)]PF6 (217 mg, 0.26
mmol) in MeOH (5 mL) was added dropwise a solution of NaBPh4
(107 mg, 0.31 mmol) in MeOH (4 mL). After the addition was
completed, the resulting mixture was stirred for 30 min. The formed
orange precipitate was collected by filtration, washed with MeOH
(2 mL × 3), then redissolved in CH2Cl2 (5 mL). The solution was
filtered through a pad of Celite. The solvent of the filtrate was
removed under vacuum to give an orange solid. Yield: 0.15 g, 57%.
1H NMR (300 MHz, CD2Cl2, 298 K): δ 0.92 (t, J(HH) ) 7.1 Hz,
CH2CH3), 2.14–2.44 (m, 4 H, PCH2), 3.46–3.90 (br, 2 H, CH2CH3),
5.01 (d, J(PH) ) 6.5 Hz, 2 H, CH2), 5.41 (d, J(PH) ) 6.8 Hz, 1 H,
CH), 6.72–7.68 (m, 45 H, Ph). 31P{1H} NMR (121.5 MHz, CD2Cl2,
298 K): δ 54.0 (d, J(PP) ) 37.8 Hz), 57.9 (d, J(PP) ) 37.8 Hz).
Anal. Calcd for C62H57BO2P2Pd: C, 73.49; H, 5.67. Found: C, 73.63;
H, 5.82.
PdI(Ph)(dppe) (16). A mixture of Pd(PPh3)4 (0.500 g, 0.433
mmol) and Ph2PCH2CH2PPh2 (175 mg, 0.44 mmol) in benzene (12
mL) was stirred for 1 h, then PhI (0.056 mL, 0.50 mmol) was added
to the mixture at room temperature. The mixture was stirred for
further 10 min. The resulting solution was allowed to stand
overnight without agitation, during which time yellow crystallites
were formed. They were collected by filtration, washed with diethyl
ether (2 mL × 3), and dried under vacuum. Yield: 0.22 g, 71%.
1H NMR (300 MHz, CD2Cl2, 298 K): δ 2.00–2.48 (m, 4 H, PCH2),
6.50–6.72 (m, 3 H, m, p- Pd-Ph), 6.97(t, J(HH) ) 7.6 Hz, 2 H,
o-Pd-Ph), 7.14–7.62 (m, 16 H, PPh), 7.72–7.96 (m, 4 H, PPh).
31P{1H} NMR (121.5 MHz, CD2Cl2, 298 K): δ 34.7 (d, J(PP) )
27.1 Hz), 49.5 (d, J(PP) ) 27.1 Hz). The NMR data are identical
to the reported ones.44
[Pd(η3-CH2C(Ph)CHCMe3)(dppe)]PF6 (17PF6). To a solution
of PdI(Ph)(dppe) (190 mg, 0.268 mmol) and tert-butylallene (27
mg, 0.28 mmol) in CH2Cl2 (8 mL) was added dropwise a solution
of TlPF6 (96 mg, 0.28 mmol) in acetone (2 mL). The resulting
yellow suspension was stirred for 30 min. The mixture was
concentrated to dryness, and CH2Cl2 (5 mL) was added. The
resulting mixture was filtered through a pad of Celite, and the Celite
was washed with CH2Cl2 (1 mL). The combined filtrates were
concentrated to dryness. The residue was washed with diethyl ether
(2 mL × 3) and dried under vacuum to give a yellow solid. Yield:
0.18 g, 82%. 1H NMR (300 MHz, CD2Cl2, 298 K): δ 0.85 (s, 9 H,
CH3), 1.94–2.18 (m, 1 H, PCH2), 2.26–2.48 (m, 1 H, PCH2),
2.54–2.88 (m, 2 H, PCH2), 4.15 (br d, J(PH) ) 9.4 Hz, 1 H, CH2),
4.49 (br m, 1 H, CH2), 5.59 (br d, J(PH) ) 5.7 Hz, CH), 6.82–7.78
(m, 25 H, Ph). 31P{1H} NMR (121.5 MHz, CD2Cl2, 298 K): δ
–143.2 (septet, J(PF) ) 713 Hz, PF6), 49.0 (d, J(PP) ) 34.3 Hz),
49.7 (d, J(PP) ) 34.3 Hz).
[Pd(η3-CH2C(Ph)CHC(O)Ph)(dppe)]PF6 (19PF6). To a solu-
tion of PdI(Ph)(dppe) (190 mg, 0.268 mmol) and 1-phenylbuta-
2,3-dien-1-one (43 mg, 0.29 mmol) in CH2Cl2 (8 mL) was added
dropwise a solution of TlPF6 (96 mg, 0.28 mmol) in acetone (2
mL). The resulting yellow suspension was stirred for 2 h. The
mixture was concentrated to dryness, and CH2Cl2 (5 mL) was added.
The resulting mixture was filtered through a pad of Celite, and the
Celite was washed with CH2Cl2 (5 mL). The combined filtrates
were concentrated to dryness. The residue was washed with diethyl
ether (5 mL × 3) and dried under vacuum to give a yellow solid.
Yield: 0.15 g, 64%. 1H NMR (300 MHz, CDCl3, 298 K): δ
2.44–2.71 (m, 4 H, PCH2), 5.19 (d, 2 H, J(PH) ) 5.4 Hz, CH2),
6.32 (d, 1 H, J(PH) ) 6.9 Hz, CH), 6.96–7.66 (m, 30 H, Ph). 31P
{1H} NMR (121.5 MHz, CDCl3, 298 K): δ –143.2 (septet, J(PF)
) 712.8 Hz, PF6), 55.5 (d, J(PP) ) 38.2 Hz), 62.3 (d, J(PP) )
38.2 Hz). Anal. Calcd for C45H44F6OP3Pd: C, 57.91; H, 4.28. Found:
C, 58.38; H, 4.63.
[Pd(η3-CH2C(Ph)CHCMe3)(dppe)]BPh4 (17BPh4). To a solu-
tion of [Pd(η3-CH2C(Ph)CHCMe3)(dppe)]PF6 (174 mg, 0.21 mmol)
in MeOH (4 mL) was added dropwise a solution of NaBPh4 (87
mg, 0.25 mmol) in MeOH (3 mL). After the addition was
completed, the resulting mixture was stirred for 2 h. The resulting
precipitate was collected by filtration, washed with MeOH (2 mL
× 3), and dried under vacuum. Column chromatography on silica
with CH2Cl2 as the eluent gave a white solid after removal of the
[Pd(η3-CH2C(Ph)CH(SO2Ph))(dppe)]BPh4 (20BPh4). To a
solution of PdI(Ph)(dppe) (190 mg, 0.268 mmol) and (propa-1,2-
dienylsulfonyl)benzene (60 mg, 0.33 mmol) in CH2Cl2 (8 mL) was
added dropwise a solution of TlPF6 (110.2 mg, 0.32 mmol) in
acetone (2 mL). The resulting yellow suspension was stirred for
2 h. The mixture was concentrated to dryness, and CH2Cl2 (6 mL)
was added. The resulting mixture was filtered through a pad of
Celite, and the Celite was washed with CH2Cl2 (5 mL × 2). The
combined filtrates were concentrated to dryness. The residue was
washed with diethyl ether (2 mL × 3) and dried under vacuum to
give 177 mg of a yellow solid. The 31P{1H} NMR (121.5 MHz,
CDCl3, 298 K) shows major peaks at δ 58.1 (d, J(PP) ) 35.4 Hz)
and 57.4 (d, J(PP) ) 35.4 Hz), -143.2 (septet, J(PF) ) 713 Hz,
PF6) ppm assignable to mainly [Pdη3-CH2C(Ph)CH(SO2Ph))-
(dppe)]PF6 and other minor peaks of unknown species at δ 56.9,
56.6, 56.3, 55.6, and 55.3 ppm. To further purify the product, the
solid was redissolved in methanol (4 mL). To the methanol solution
of [Pdη3-CH2C(Ph)CH(SO2Ph))(dppe)]PF6 (177 mg, ca. 0.20 mmol)
was added dropwise a solution of NaBPh4 (83 mg, 0.24 mmol) in
MeOH (3 mL). After the addition was completed, the resulting
mixture was stirred for 2 h. The resulting precipitate was collected
1
solvents. Yield: 145 mg, 69%. H NMR (300 MHz, CD2Cl2, 298
K): δ 0.85 (s, 9 H, CH3), 1.80–2.02 (m, 1 H, PCH2), 2.08–2.34
(m, 1 H, PCH2), 2.34–2.72 (m, 2 H, PCH2), 4.14 (br dt, J(PH) )
9.5 Hz, J(HH) ) 1.7 Hz, 1 H, CH2), 4.47 (br m, 1 H, CH2), 5.58
(br dd, J(PH) ) 5.7 Hz, J(HH) ) 1.7 Hz, CH), 6.74–7.78 (m, 45
H, Ph). 31P{1H} NMR (121.5 MHz, CD2Cl2, 298 K): δ 49.0 (d,
J(PP) ) 34.3 Hz), 49.7 (d, J(PP) ) 34.3 Hz). Anal. Calcd for
C63H61BP2Pd: C, 75.87; H, 6.16. Found: C, 75.76; H, 6.41.
[Pd(η3-CH2C(Ph)CHCO2Et)(dppe)]PF6 (18PF6). To a solution
of PdI(Ph)(dppe) (190 mg, 0.268 mmol) and ethyl 2,3-butadienoate
(31 mg, 0.28 mmol) in CH2Cl2 (8 mL) was added dropwise a
solution of TlPF6 (96 mg, 0.28 mmol) in acetone (1.5 mL). The
resulting suspension was stirred for 30 min. After removal of the

2626 Organometallics, Vol. 27, No. 11, 2008
Bai et al.
by filtration, washed with MeOH (2 mL × 3), and dried under
vacuum. Column chromatography on silica gel with CH2Cl2 as the
eluent gave a yellow solid after removal of the solvents. Yield:
137 mg, overall yield, 47%. 1H NMR (300 MHz, CDCl3, 298 K):
δ 1.65–2.30 (m, br, 4 H, PCH2), 4.78–4.85 (br m 1 H, CH2),
5.08–5.17 (br m, 1 H, CH2), 5.36–5.44 (m, br, 1 H, CH), 6.51 (d,
2 H, J(HH) ) 6.9 Hz, Ph), 6.72–7.85 (m, 48 H, PPh, Ph). 31P{1H}
NMR (121.5 MHz, CDCl3, 298 K): δ 58.2 (d, J(PP) ) 35.0 Hz),
57.7 (d, J(PP) ) 35.0 Hz). Anal. Calcd for C65H57BO2P2PdS: C,
72.19; H, 5.31. Found: C, 71.70; H, 5.58.
structures were all solved by direct methods. All of the structures
were refined smoothly. Otherwise, all non-hydrogen atoms were
refined anisotropically by full-matrix least-squares, with a riding
model for the hydrogen atoms.
Computational Details. Molecular geometries were optimized
at the Becke3LYP (B3LYP) level of density functional theory.
Frequency calculations at the same level of theory have also been
performed to identify all stationary points as minima (zero
imaginary frequency). The effective core potentials (ECPs) of Hay
and Wadt with a double- valence basis set (LanL2DZ) were used
to describe Pd, P, S, and I atoms,48 while the standard 6-31G basis
set was used for C, O, and H atoms. Polarization functions were
added for P ( (d) ) 0.34), S ( (d) ) 0.421), I ( (d) ) 0.266), the
three allene carbon atoms, and the metal-bonded carbon atom of
the phenyl ligand (C (d) ) 0.8).49 Calculations of intrinsic reaction
coordinates (IRC)50 were also performed on transition states to
confirm that such structures are indeed connecting two minima.
All the calculations were performed with the Gaussian 03 software
package.51 The natural bond orbital (NBO) program,52 as imple-
mented in Gaussian 03, was also used to obtain natural populations
of atoms.53
[Pd(η3-CH(Me)C(Ph)CH(SO2Ph))(dppe)]PF6 (21PF6). To a
solution of PdI(Ph)(dppe) (190 mg, 0.268 mmol) and (buta-1,2-
dienylsulfonyl)benzene (56 mg, 0.29 mmol) in CH2Cl2 (8 mL) was
added dropwise a solution of TlPF6 (96 mg, 0.28 mmol) in acetone
(2 mL). The resulting green suspension was stirred for 2 h. The
mixture was concentrated to dryness, and CH2Cl2 (6 mL) was added.
The resulting mixture was filtered through a pad of Celite, and the
Celite was washed with CH2Cl2 (6 mL). The combined filtrates
were concentrated to dryness. Column chromatography on silica
with CH2Cl2 as the eluent gave a yellow solid after removal of the
1
solvents. Yield: 157 mg, 64%. H NMR (300 MHz, CDCl3, 298
K): δ 1.36 (dd, 3 H, J(PH) ) 12.9 Hz, J(HH) ) 6.6 Hz, CH3),
2.45–2.74 (m, 2 H, PCH2), 2.95–3.10 (m, 2 H, PCH2), 4.84 (d, 1
H, J(PH) ) 6.3 Hz, CHdCPh), 6.24–6.34 (m, 1 H, CHMe), 6.39
(d, J(HH) ) 7.2 Hz, Ph), 7.00–7.91 (m, 28 H, PPh2, Ph). 31P{1H}
NMR (121.5 MHz, CDCl3, 298 K): δ –143.2 (septet, J(PF) ) 713
Hz, PF6), 56.5 (d, J(PP) ) 33.4 Hz), 56.8 (d, J(PP) ) 33.4 Hz).
Anal. Calcd for C42H39F6O2P3PdS: C, 54.76; H, 4.27. Found: C,
54.32; H, 4.75.
Crystal Structure Analyses of 3, trans-5, trans-9, cis-11,
cis-13, and cis-15. Single crystals of 3 suitable for X-ray diffraction
were obtained by slow evaporation of solvent from a CH3CN
solution. Single crystals of trans-5, trans-9, cis-11, cis-13, and cis-
15 suitable for X-ray diffraction were obtained by layering ether
(cis-13, trans-9) or n-hexane (trans-5, cis-11, cis-15) on top of their
CH2Cl2 solutions. The compounds are sufficiently air stable to be
mounted on glass fibers with epoxy adhesive. The diffraction
intensity data were collected with a Bruker Smart APEX CCD
diffractometer with graphite-monochromated Mo KR radiation (λ
) 0.71073 Å) at 100 K for 3 and trans-5 and 298 K for the rest.
Lattice determination and data collection were carried out using
SMART v.5.625 software. Data reduction and absorption correction
by empirical methods were performed using SAINT v 6.26 and
SADABS v 2.03, respectively. Structure solution and refinement
were performed using the SHELXTL v.6.10 software package. The
Acknowledgment. We are thankful for the financial
support from the National Natural Science Foundation of
China (20429201), the Chinese Academy of Sciences, and
Hong Kong Research Grant Council (601505).
Supporting Information Available: Complete ref 51, tables
giving Cartesian coordinates and electronic energies for all of the
calculated structures, and CIF files giving X-ray crystallographic
data. This material is available free of charge via the Internet at
http://pubs.acs.org.
OM800030A
(48) (a) Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284. (b) Hay,
P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299.
(49) Huzinaga, S. Gaussian Basis Sets for Molecular Calculations;
Elsevier Science Pub. Co.: Amsterdam, 1984..
(50) (a) Fukui, K. J. Phys. Chem. 1970, 74, 4161. (b) Fukui, K. Acc.
Chem. Res. 1981, 14, 363.
(51) Frisch, M. J.; et al. Gaussian 03, reVision B05; Gaussian, Inc.:
Pittsburgh, PA, 2003.
(52) Glendening, E. D.; Reed, A. E.; Capenter, J. E.; Weinhold, F. NBO
Version 3.1.
(53) Wiberg, K. B. Tetrahedron 1968, 24, 1083.