Mono- and dipalladium movement on the π-conjugated five-carbon chain

Article abstract of DOI:10.1021/om700909k

We prepared new mono- and dipalladium complexes containing a highly conjugated pentadiynyl ligand where the palladium movement to the C5 position with the bonding rearrangement provided the first cumulenyl-type complexes.

Full text of DOI:10.1021/om700909k

276
Organometallics 2008, 27, 276–280
Mono- and Dipalladium Movement on the π-Conjugated
Five-Carbon Chain
Yoshiteru Takahashi,† Ken Tsutsumi,*,† Yuzo Nakagai,† Tsumoru Morimoto,†
Kiyomi Kakiuchi,† Sensuke Ogoshi,§ and Hideo Kurosawa§
Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), Takayama,
Ikoma, Nara 630-0192, Japan, and Department of Applied Chemistry, Faculty of Engineering, Osaka
UniVersity, Suita, Osaka 565-0871, Japan
ReceiVed September 12, 2007
We prepared new mono- and dipalladium complexes containing a highly conjugated pentadiynyl ligand
where the palladium movement to the C5 position with the bonding rearrangement provided the first
cumulenyl-type complexes.
Chart 1. Palladium Movements on Five-Carbon Chain
Introduction
The 1,3-metal shift on an allyl, a propargyl, and an allenyl
ligand is very common for both transition metals and typical
metals.1 Usually, the metal moves reversibly on three carbons
and the position of the metal is governed by the thermodynamic
stability of the complex. We reported the synthesis of mono-
and dinuclear palladium complexes containing a propargyl/
allenyl ligand.2 Dinuclear complexes reveal the unique µ-η3-
coordination of the Pd-Pd unit to three carbons. In an extension
of these studies, we focused on the metal dynamics of the more
expanded sp-hybridized polyyne system pentadiyne.3 In this
system metal movements of a longer distance (A-C) as well
as novel dimetal movements (D-G) are possible, which may
be referred to as metal trains on a rail such as those found in
new switchable-type devices (Chart 1).4 Notably, Pd movement
to the C5 position with the bonding rearrangement may afford
first cumulenyl-type complexes C and G. Herein, we report the
synthesis of palladium complexes bearing a pentadiynyl ligand
and the controlling of the palladium movement on the π-con-
jugated five-carbon chain.
temperature gave a mixture of complexes η1-(penta-2,4-diyn-
1-yl)- and η1-(penta-1,2-dien-4-yn-3-yl)palladium (2a, 3a) in a
ratio of 44:56 (Table 1, entry 1). Elemental analysis on the
mixture shows that the expected composition and NMR spectral
data of 2a and 3a are very close to those of the reported η1-
propargyl- and η1-allenylpalladium complexes.2a,5 To the best
of our knowledge, reported η1-pentadiynyl transition-metal
complexes have been limited to Mo and Fe, where 1,3-metal
shift on the diynyl ligand has not been observed.6 Similarly
bromide analogues 2b and 3b were obtained (entry 2). In
contrast, the methyl-substituted pentadiynyl chlorides 1c or 1d
afforded only η1-(penta-1,2-dien-4-yn-3-yl)palladium 3c or 3d
quantitatively (entries 3 and 4). Further isomerization to the
cumulenyl-type complexes 4 did not occur even at 50 °C in
CDCl3 for 12 h. The structure of 3a was confirmed by X-ray
crystallography (Figure 1). X-ray study shows that the five
carbons in the allenyl-yne unit and the terminal phenyl ring in
complex 3a exist approximately on one plane, which suggests
the presence of an extended π orbital at the C2-C11 moiety.
The reaction of 1a or 1d with 2 equiv of Pd(PPh3) complex
generated from 1 equiv of Pd2(dba)3 and 2 equiv of PPh3 in
CDCl3 at room temperature gave dipalladium complex 5a or
5d as the sole product (Scheme 1). The structure of 5d was
confirmed by X-ray crystallography (Figure 2). The spectral data
are completely consistent with those of the reported µ-η3-
propargyl/allenyldipalladium complexes.2c These palladium
complexes did not isomerize to the cumulenyl complexes 6 even
at 50 °C in CDCl3 for 12 h.
Results and Discussion
The reactions of pentadiynyl halide 1a with Pd(PPh3)2
complex generated from 0.5 equiv of Pd2(dba)3 · CHCl3 (dba )
dibenzylideneacetone) and 2 equiv of PPh3 in CDCl3 at room
* To whom correspondence should be addressed. Phone: +81-743-72-
6084. Fax: +81-743-72-6089. E-mail: tsutsumi@ms.naist.jp.
† Nara Institute of Science and Technology (NAIST).
§ Osaka University.
(1) (a) Principles and Applications of Organotransition Metal Chemistry;
Collman, J. P., Hegedus, L. S., Norton, J. R., Finke, R. G., Eds.; University
Science Books, 1987. (b) AdVances in Organometallic Chemistry, Vol. 37;
Stone, F. G., West, R., Eds.; Academic Press: New York, 1995; pp 39–
130. (c) Liang, K.-W.; Lee, G.-H.; Peng, S.-M.; Liu, R.-S. Organometallics
1995, 14, 2353–2360, and references therein.
(2) Mononuclear complexes: (a) Tsutsumi, K.; Kawase, T.; Kakiuchi,
K.; Ogoshi, S.; Okada, Y.; Kurosawa, H. Bull. Chem. Soc. Jpn. 1999, 72,
2687–2692. (b) Tsutsumi, K.; Ogoshi, S.; Nishiguchi, S.; Kurosawa, H.
J. Am. Chem. Soc. 1998, 120, 1938–1939. Dinuclear complexes: (c) Ogoshi,
S.; Nishida, T.; Tsutsumi, K.; Ooi, M.; Shinagawa, T.; Akasaka, T.; Yamane,
M.; Kurosawa, H. J. Am. Chem. Soc. 2001, 123, 3223–3228.
(3) Acetylene Chemistry: Chemistry, Biology, and Material Science;
Diederich, F., Stang, P. J., Tykwinski, R. R., Eds.; Wiley-VCH: Weinheim,
Germany, 2005; pp 397–426.
For attaining the coordination of the C5 atom to the palladium
unit, the steric repulsion between the substituent at the acetylene
(5) Elsevier, C. J.; Kleijn, H.; Boersma, J.; Vermeer, P. Organometallics
1986, 5, 716–720.
(4) Amendola, V.; Fabbrizzi, L; Mangano, C.; Pallavicini, P Acc. Chem.
Res. 2001, 34, 488–493, and references therein.
(6) Giulieri, F.; Benaim, J. J. Organomet. Chem. 1984, 276, 367–376.
10.1021/om700909k CCC: $40.75
2008 American Chemical Society
Publication on Web 01/04/2008

Mono- and Dipalladium Complexes
Organometallics, Vol. 27, No. 2, 2008 277
Table 1. Reaction of Pentadiynyl Halides with Pd(PPh3)2
entry
1
R1
R2
R3
Ph
X
yield (%)a
complex
2
:
3
:
4
1
2
3
4
1a
1b
1c
1d
H
H
Me
Me
H
H
H
Me
Cl
Br
Cl
Cl
77
74
quant.
quant.
2a + 3a
2b + 3b
3c
44
46
0
:
:
:
:
56
54
100
100
:
:
:
:
0
0
0
0
Ph
Ph
TESb
3d
0
1
a Determined by H NMR spectroscopy. b TES ) Et3Si.
Figure 1. Molecular structure of 3a drawn with thermal ellipsoids
at the 50% probability level. All hydrogen atoms are omitted for
clarity. Selected bond distances (Å) and angles (deg): C(1)-C(2)
) 1.312(9), C(2)-C(3) ) 1.286(7), C(3)-C(4) ) 1.430(8),
C(4)-C(5) ) 1.199(9), C(3)-Pd ) 2.025(4), C(1)-C(2)-C(3) )
178.9(6), C(2)-C(3)-C(4) ) 126.4(4), C(3)-C(4)-C(5) )
174.5(5).
Figure 2. Molecular structure of 5d drawn with thermal ellipsoids
at the 50% probability level. All hydrogen atoms are omitted for
clarity. Selected bond distances (Å) and angles (deg): C(1)-C(2)
) 1.408(9), C(2)-C(3) ) 1.274(9), C(3)-C(4) ) 1.419(10),
C(4)-C(5) ) 1.177(11), Pd(1)-Pd(2) ) 2.6443(5), Pd(1)-C(1)
) 2.083(6), Pd(1)-C(2) ) 2.229(7), Pd(2)-C(2) ) 2.339(6),
Pd(2)-C(3) ) 2.000(6), C(1)-C(2)-C(3) ) 165.2(7).
Scheme 1. Reaction of Pentadiynyl Chlorides with 2Pd(PPh3)
Scheme 2. Desilylation of 5e with Silica Gel
when smaller amounts of HCl were added. We previously found
that the protonation of µ-η3-propargyl/allenyldipalladium with
HCl gave µ-vinylcarbenedipalladium,2c so the corresponding
complex 8 may be produced first. A second protonation may
occur at the C5 carbon to give η3-allylmonopalladium 9,
followed by protonation again at the C5 carbon to provide 7.
The reaction of 3d with HCl produced the dien-yne compound
(Me2CdCdCHCt CTES). Therefore the triprotonation is based
on the dipalladium coordination.
terminal and the phosphine Ph group seems too large, so we
planned to reduce the steric repulsion in order to cause the Pd
unit to migrate. However no diynyl halide without protection
at the acetylene terminal is available due to its low stability.
Thus we first prepared the triethylsilyl (TES)-protected complex
5d from the comparably stable 1d7 and then examined the
desilylation to reduce the steric repulsion. We found that the
treatment of silyl-substituted propargyl/allenyldipalladium com-
plex 5e2c with silica gel provided the desilylated complex 5e-H
(Scheme 2). However TES group of 5d could not be removed
under similar conditions.
Finally, the TES group could be removed by adding tetrabu-
tylammonium fluoride (TBAF) (Scheme 4). In the reaction of
1
5d the H NMR spectrum shows a new double-doublet signal
at 5.93 ppm with 31.5 and 2.8 Hz coupling constants (JHP),
which is very close to the methyne proton signal of the reported
µ-η3-propargyl/allenyldipalladium complex 5e-H.2c The P-P
coupling constant is extremely large (74.4 Hz), which indicates
that the four atoms P-Pd-Pd-P exist almost in a straight line.2c
In 13C NMR C-P couplings are observed on three signals at
73.00, 76.98, and 87.37 ppm, which are assigned to the µ-η3-
coodinating carbons, while a free cumulenyl carbon (C2)
observed at 187.68 ppm also shows a C-P coupling. The methyl
More surprisingly, when we treated 5d with HCl (generated
from a reaction of H2O with Me3SiCl in situ), desilylation
reaction did not take place, but an unexpected product 7 from
triprotonation at the C2 and C5 carbons was obtained (Scheme
3). Unfortunately, reaction intermediates were not detected even
(7) Triethylsilyl-protected pentadiynyl alcohol, which is a pre-material
of 1d, was prepared according to the literature procedure; see: Marino, J. P.;
Nguyen, H. N. J. Org. Chem. 2002, 67, 6841–6844.

278 Organometallics, Vol. 27, No. 2, 2008
Takahashi et al.
Scheme 3. Reaction of 5d with HCl
penta-2,4-diyn-1-ol10 and 6-phenylhexa-3,5-diyn-2-ol11 were pre-
pared according to the published methods.
Preparation of (5-Chloropenta-1,3-diynyl)benzene/ClCH2C
t CCt CPh (1a). To a solution of 1.00 g (6.40 mmol) of
5-phenylpenta-2,4-diyn-1-ol and 1.70 g (6.48 mmol) of Ph3P in
300 mL of dry THF was added 0.855 g (6.40 mmol) of NCS under
nitrogen atmosphere. The reaction mixture was stirred at room
temperature for 1 h. The mixture was diluted with hexane and
passed through a pad of silica gel to remove the precipitated Ph3PO.
The obtained residue was purified by a silica gel column (silica
gel 60N, hexane/Et2O, 9:1) to give 860 mg (77% isolated yield) of
1a as a yellow oil. HRMS calcd for C11H7Cl: 174.0236. Found:
1
174.0228. H NMR (500.16 MHz, CDCl3): δ 4.29 (s, 2H), 7.33
Scheme 4. Desilylation of 5d and 3d Using TBAF
(dd, 3JHH ) 7.3 Hz, 7.3 Hz, 2H), 7.39 (t, 3JHH ) 7.3 Hz, 1H), 7.50
(d, 3JHH ) 7.3 Hz, 2H). 13C NMR (125.77 MHz, CDCl3): δ 30.8,
71.0, 72.9, 76.5, 79.5, 121.1, 128.4, 129.5, 132.6.
Preparation of (5-Bromopenta-1,3-diynyl)benzene/BrCH2C
t CCt CPh (1b). Bromination of 5-phenylpenta-2,4-diyn-1-ol using
NBS gave 1b (69% isolated yield, yellow oil). HRMS calcd for
C11H7Br: 217.9731. Found: 217.9605. 1H NMR (500.16 MHz,
CDCl3): δ 4.06 (s, 2H), 7.34 (dd, 3JHH ) 7.3 Hz, 7.3 Hz, 2H), 7.39
3
3
(t, JHH ) 7.3 Hz, 1H), 7.51 (d, JHH ) 7.3 Hz, 2H). 13C NMR
(125.77 MHz, CDCl3): δ 14.6, 71.3, 73.1, 76.8, 79.8, 121.0, 128.3,
129.4, 132.5.
Preparation of (5-Chlorohexa-1,3-diynyl)benzene/ClCH-
(Me)Ct CCt CPh (1c). Chlorination of 6-phenylhexa-3,5-diyn-
2-ol gave 1c (70% isolated yield, yellow oil). HRMS Calcd for
C12H9Cl: 188.0393. Found: 188.0395. 1H NMR (500.16 MHz,
proton and carbon resonances of 5d have phosphorus couplings:
4
1H NMR δ 1.08 (d, JHP ) 4.3 Hz, (CH3)2CCC); 13C NMR δ
3
CDCl3): δ 1.83 (d,3JHH ) 6.8 Hz, 3H), 4.80 (q, JHH ) 6.8 Hz,
25.38 (d, 3JCP ) 4.8 Hz, (CH3)2CCC). For 6-H the correspond-
ing phosphorus couplings disappear. These spectral data and
elemental analysis may correspond with a novel cumulenyldi-
palladium complex, 6-H. Other isomers were not observed in
this reaction, so the Pd-Pd unit might move on the five-carbon
unit as soon as the silyl-stopper is taken off. On the contrary,
the similar desilylation reaction of 3d gave the mixture of dien-
yn-yl complex 3-H and tetraenyl complex 4-H, which is the
first example of η1-cumulenyl metal complexes (3-H:4-H )
52:48). These complexes gradually decompose in a solution
without changing the ratio, which indicates that monopalladium
moves reversibly between the C3 and C5 carbons. 1,3-Metal
shift on the propargyl/allenyl transition-metal complexes has
been discussed including the mechanistic aspects in both metal
complexes8 and catalytic reactions.9 To the best of our
knowledge, this is the first report of the dimetal movement on
a five-carbon unit, so-called (1–3),(3–5)-dimetal shift.
1H), 7.36 (dd, 3JHH ) 7.3 Hz, 7.3 Hz, 2H), 7.41 (t, 3JHH ) 7.3 Hz,
1H), 7.52 (d, 2JHH ) 7.3 Hz, 2H). 13C NMR (125.77 MHz, CDCl3):
δ 26.1, 44.0, 70.0, 72.8, 80.0, 80.7, 121.1, 128.4, 129.5, 132.6.
Preparation of (5-Chloro-5-methylhexa-1,3-diynyl)triethyl-
silane/ClCMe2Ct CCt CSiEt3 (1d). The preparation of 1d was
carried out similarly to the literature procedure.12 CuCl (0.10 g,
1.01 mmol) was added to a 30% n-BuNH2 (42.1 mL) aqueous
solution at room temperature, which resulted in the formation of a
blue solution immediately. A few crystals of hydroxylamine
hydrochloride were added to discharge the blue color. Triethyl-
(ethynyl)silane (8.5 g, 60.6 mmol) was added to the solution at
room temperature, forming a yellow acetylide suspension, which
was immediately cooled with an ice–water mixture. 1-Bromo-3-
chloro-3-methylbut-1-yne (9.19 g, 50.5 mmol) was added at once,
and the ice bath was removed. More crystals of hydroxylamine
hydrochloride were added throughout the reaction as necessary to
prevent the solution from turning blue. After several additions of
hydroxylamine hydrochloride crystals, the reaction mixture had a
rusty color. After 30 min, the reaction was complete according to
TLC. The product was repeatedly extracted with diethyl ether, dried
over MgSO4, and concentrated under reduced pressure. The crude
product could be purified by a silica gel column (silica gel 60N,
hexane only) to give 5.91 g (49% isolated yield) of 1d as a colorless
In conclusion, we prepared new mono- and dipalladium
complexes containing a pentadiynyl ligand and found palladium
movement on the conjugated five-carbon unit.
Experimental Section
1
oil. HRMS calcd for C13H21ClSi: 240.1101. Found: 240.1102. H
General Procedures. Most of the commercially available
reagents were used without further purification. All reactions and
manipulations of air- and moisture-sensitive compounds were
carried out under an atmosphere of dry N2 by use of standard
vacuum line techniques. 1H NMR, 31P NMR, and 13C NMR were
recorded on a JEOL JNM-ECP500 spectrometer. The H and C
contents were determined from an elemental analysis using a Perkin-
Elmer 2900II CHNS/O analyzer. Melting points were determined
on a Yanaco MP-500D micro melting point apparatus. 5-Phenyl-
NMR (500.16 MHz, CDCl3): δ 0.62 (q, 3JHH ) 7.9 Hz, 6H), 0.99
3
(t, JHH ) 7.9 Hz, 9H), 1.86 (s, 6H). 13C NMR (125.77 MHz,
CDCl3): δ 4.1, 7.3, 34.3, 57.4, 69.0, 78.3, 87.7, 87.8.
Preparation of η1-(Penta-2,4-diyn-1-yl)palladium Complex/
(PPh3)2ClPdCH2Ct CCt CPh (2a) and η1-(Penta-1,2-dien-4-
yn-3-yl)palladium Complex/[CH2dCdC(Ct CPh)]PdCl(PPh3)2
(3a). To a dry THF solution (50 mL) of 772 mg (0.668 mmol) of
Pd(PPh3)4 was added 129 mg (0.739 mmol) of (5-chloropenta-1,3-
diynyl)benzene 1a under nitrogen atmosphere. After 15 min at room
temperature, the volume of the solvent was reduced to half by a
rotary evaporator. After the addition of 600 mL of pentane, the
(8) Ogoshi, S.; Fukunishi, Y.; Tsutsumi, K.; Kurosawa, H. Inorg. Chim.
Acta 1997, 265, 9–15, and references therein.
(9) Tsuji, J. Palladium Reagents and Catalysts; John Wiley & Sons:
Chichester, 1995; pp 453–471.
(10) Bradsma, L. PreparatiVe Acetylenic Chemistry; Elsevier: New York,
1971.
(11) Nash, B. W.; Thomas, D. A.; Warburton, W. K.; Williams, T. D.
J. Chem. Soc. 1965, 2983–2988.
(12) Marino, J. P.; Nguyen, H. N. J. Org. Chem. 2002, 67, 6841–6844.

Mono- and Dipalladium Complexes
Organometallics, Vol. 27, No. 2, 2008 279
yellow precipitate obtained was collected on a glass filter and
washed with diethyl ether and pentane. The yellow mixture of 2a
and 3a was dried under vacuum in 69% isolated yield (369 mg).
In the case of the NMR study, to a CDCl3 solution (0.6 mL) of 3.5
mg (0.020 mmol) of diynylchloride 1a were added 10.4 mg (0.010
mmol) of Pd2(dba)3 · CHCl3 and 10.5 mg (0.040 mmol) of PPh3
under nitrogen atmosphere. The reaction was monitored by 1H and
31P NMR. After 30 min at room temperature, 2a and 3a were
yielded (77%, 2a:3a ) 44:56); mp 148.8–151.5 °C (dec). Anal.
Calcd for C47H37ClP2Pd · CH2Cl2: C 64.79, H 4.41. Found: C 64.53,
2JHH ) 7.3 Hz, 2H), 7.09 (dd, 2JHH ) 7.3 Hz,2JHH ) 7.3 Hz, 2H),
2
7.16 (t, JHH ) 7.3 Hz, 1H), 7.30–7.37 (m, 9H), 7.39–7.43 (m,
9H), 7.63–7.71 (m, 12H). 31P NMR (202.46 MHz, CDCl3): δ 27.7
3
3
(d, JPP ) 83.0 Hz), 32.1 (d, JPP ) 83.0 Hz). 13C NMR (125.77
MHz, CDCl3): δ 9.34 (d, 2JCP ) 2.5 Hz), 81.3 (d, 3JCP ) 19.9 Hz),
98.6 (d, JCP ) 1.7 Hz), 109.6 (dd,
2
2,2
J
CP
) 12.4, 3.3 Hz), 123.8.
TES-Ethynyl-Dipalladium Complex/(PPh3)2ClPd2[Me2CCC-
(Ct CSiEt3)] (5d): 61% isolated yield (85% NMR yield); mp
160.3–166.9 °C (dec). Anal. Calcd for C49H51ClP2Pd2Si: C 60.16,
H 5.25. Found: C 60.19, H 5.16. 1H NMR (500.16 MHz, CDCl3):
1
3
H 4.39. 2a: H NMR (500.16 MHz, CDCl3) δ 1.32 (t, JHP ) 6.4
Hz, 2H), 7.32–7.38 (m, 9H), 7.40–7.46 (m, 14H), 7.77–7.82 (m,
12H). 31P NMR (202.46 MHz, CDCl3): δ 26.9 (s). 13C NMR
(125.77 MHz, CDCl3): δ 5.71, 70.0, 83.5 (t, 3JCP ) 2.5 Hz), 94.3,
3
3
δ 0.29 (q, JHH ) 7.8 Hz, 6H), 0.73 (t, JHH ) 7.8 Hz, 9H), 1.08
4
(d, JHP ) 4.3 Hz, 6H), 7.33–7.39 (m, 18H), 7.64–7.73 (m, 12H).
31P NMR (202.46 MHz, CDCl3): δ 25.27 (d, 3JPP ) 60.5 Hz), 33.64
(d, 3JPP ) 60.5 Hz). 13C NMR (125.77 MHz, CDCl3): δ 4.06, 7.38,
1
5
124.9. 3a: H NMR (500.16 MHz, CDCl3) δ 3.31 (t, JHP ) 2.8
Hz, 2H), 6.96–6.99 (m, 2H), 7.18–7.21 (m, 3H), 7.32–7.38 (m, 6H),
7.40–7.46 (m, 12H), 7.77–7.82 (m, 12H). 31P NMR (202.46 MHz,
CDCl3): δ 23.1 (s). 13C NMR (125.77 MHz, CDCl3): δ 67.1, 86.4
3
2
25.38 (d, JCP ) 4.8 Hz), 34.47, 79.37, 97.20 (d, JCP ) 18.23
2,2
Hz), 104.38, 110.54 (dd,
J
CP
) 16.79, 8.16 Hz). Crystal data for
5d: M ) 978.23, yellow, triclinic, a ) 9.161(4) Å, b )15.238(6)
Å, c ) 18.554(9) Å, R ) 94.636(18)°, ꢀ ) 97.931(18)°, γ )
91.766(15)°, V ) 2554.8(19) Å3, Z ) 2, Dcalcd ) 1.272 g/cm3, T
) 296.1 K, R(Rw) ) 0.0775 (0.0652), CCDC file number 281585.
Reaction of 5d with HCl. To a solution of 9.8 mg (0.010 mmol)
of 5d in 0.6 mL of CDCl3 were added ca. 1 µL of H2O and 3.8 mg
(0.035 mmol) of (CH3)3SiCl under nitrogen atmosphere. The
mixture changed to a yellow suspension within 10 min. The reaction
was monitored by 1H and 31P NMR. After 2 h at room temperature,
ene-yne compound 7 was yielded (54%). HRMS calcd for C13H24Si:
208.1647. Found: 208.1646. 1H NMR (500.16 MHz, CDCl3): δ
0.64 (q, 3JHH ) 7.9 Hz, 6H), 0.97 (t, 3JHH ) 7.9 Hz, 9H), 1.64 (d,
5JHH ) 1.8 Hz, 2H), 1.76 (s, 3H), 1.85 (s, 3H), 5.23–5.22 (m, 1H).
13C NMR (125.77 MHz, CDCl3): δ 2.67, 3.18, 7.28, 20.60, 24.56,
89.76, 106.07, 106.11, 145.21.
3
3
(t, JCP ) 2.4 Hz), 88.7, 123.3, 205.4 (t, JCP ) 4.1 Hz). Crystal
data for 3a: M ) 890.54, yellow, monoclinic, a ) 12.987(4) Å, b
)17.217(5) Å, c ) 19.018(5) Å, R ) 90.0000°, ꢀ ) 100.673(11)°,
γ ) 90.0000°, V ) 4179(2) Å3, Z ) 4, Dcalcd ) 1.415 g/cm3, T )
243.1 K, R(Rw) ) 0.0682 (0.0829), CCDC file number 281584.
η1-(Penta-2,4-diyn-1-yl)palladium Complex/(PPh3)2BrPd-
CH2Ct CCt CPh (2b) and η1-(Penta-1,2-dien-4-yn-3-yl)palla-
dium Complex/[CH2dCdC(Ct CPh)]PdBr(PPh3)2 (3b): 71%
isolated yield (74% NMR yield, 2b:3b ) 46:54); mp 137.8–139.4
°C (dec). Anal. Calcd for C47H37BrP2Pd: C 66.41, H 4.39. Found:
1
C 66.56, H 4.55. 2b: H NMR (500.16 MHz, CDCl3) δ 1.51 (t,
3JHP ) 5.9 Hz, 2H), 7.28–7.57 (m, 23H), 7.65–7.81 (m, 12H). 31
P
NMR (202.46 MHz, CDCl3): δ 26.8 (s). 13C NMR (125.77 MHz,
CDCl3): δ 8.77, 70.7, 86.0, 94.8, 124.9. 3b: 1H NMR (500.16 MHz,
CDCl3) δ 3.37 (t, 5JHP ) 2.8 Hz, 2H), 6.96–6.98 (m, 2H), 7.17–7.22
(m, 3H), 7.28–7.57 (m, 18H), 7.65–7.81 (m, 12H). 31P NMR
(202.46 MHz, CDCl3): δ 23.1 (s). 13C NMR (125.77 MHz, CDCl3):
Reaction of 3d with HCl. To a solution of 8.7 mg (0.010 mmol)
of 3d in 0.6 mL of CDCl3 were added ca. 1 µL of H2O and 1.2 mg
(0.011 mmol) of (CH3)3SiCl under nitrogen atmosphere. The
mixture changed to a yellow suspension within 10 min. The reaction
was monitored by 1H and 31P NMR. After 30 min at room
temperature, a diene-yne compound was yielded (89%). HRMS
calcd for C13H22Si: 206.1491. Found: 206.1490. 1H NMR (500.16
3
δ 67.2, 86.1, 88.3, 123.3, 205.2 (t, JCP ) 4.9 Hz).
η1-(Penta-1,2-dien-4-yn-3-yl)palladium Complex/[MeCHd
CdC(Ct CPh)]PdCl(PPh3)2 (3c): 72% isolated yield (>99%
NMR yield); mp 145.1–147.6 °C (dec). Anal. Calcd for
C48H39ClP2Pd: C 70.34, H 4.80. Found: C 70.36, H 4.81. 1H NMR
3
3
MHz, CDCl3): δ 0.66 (q, JHH ) 7.9 Hz, 6H), 0.98 (t, JHH ) 7.9
5
5
Hz, 9H), 1.88 (d, JHH ) 3.1 Hz, 6H), 5.64 (sept, JHH ) 3.1 Hz,
1H).
3
(500.16 MHz, CDCl3): δ 0.87 (d, JHH ) 7.0 Hz, 3H), 3.86 (q,
3JHH ) 7.0 Hz, 1H), 6.93–6.96 (m, 2H), 7.16–7.20 (m, 3H),
7.34–7.44 (m, 12H), 7.61–7.65 (m, 6H), 7.77–7.81 (m, 12H). 31P
NMR (202.46 MHz, CDCl3): δ 20.0 (brs), 20.4 (brs). 13C NMR
(125.77 MHz, CDCl3): δ 12.4, 79.9, 82.6, 87.3, 93.2, 202.7 (t, 3JCP
) 3.9 Hz).
Desilylation of 5d with TBAF. A 50 mL three-necked flask
equipped with a magnetic bar was charged with 97.8 mg (0.100
mmol) of 5d and 20.0 mL of THF. The flask was degassed with
nitrogen and placed into a cooling bath at -40 °C. After the solution
was stirred vigorously for 5 min, 110 µL (0.110 mmol) of TBAF
(in 1 M THF) was added to it, and the temperature was allowed to
rise at -20 °C (it took 30 min). Then 2.0 mL of H2O was added
dropwise to the solution, and the resulting mixture was stirred for
10 min at -20 °C. The reaction mixture was extracted with CH2Cl2,
and the combined organic layers were washed with brine and dried
over anhydrous Mg2SO4. Removal of the solvents under vacuum
afforded a residue that was chromatographed on silica gel (Wakogel
C200) with benzene; 6-H was yielded (58%). In the case of the
NMR study, to a solution of 4.9 mg (0.0050 mmol) of 5d in 0.5
mL of THF-d8 was added 4.4 mg (0.0055 mmol) of TBAF (on
silica gel, 1.0–1.5 mmol F/g resin) under nitrogen atmosphere. The
reaction was monitored by 1H and 31P NMR. After 30 min at room
temperature, 6-H was yielded (62%); mp 129.7–132.0 °C (dec).
Anal. Calcd for C43H37ClP2Pd2: C 59.78, H 4.32. Found: C 59.76,
η1-(Penta-1,2-dien-4-yn-3-yl)palladium Complex/[Me2Cd
CdC(Ct CSiEt3)]PdCl(PPh3)2 (3d): 73% isolated yield (>99%
NMR yield); mp 141.2–143.9 °C (dec). Anal. Calcd for
C49H51ClP2PdSi: C 67.50, H 5.90. Found: C 67.45, H 5.87. 1H NMR
(500.16 MHz, CDCl3): δ 0.86 (t, 3JHH ) 7.8 Hz, 9H), 0.71 (s, 6H),
3
0.40 (q, JHH ) 7.8 Hz, 6H), 7.33–7.41 (m, 18H), 7.71–7.76 (m,
12H). 31P NMR (202.46 MHz, CDCl3): δ 21.34 (s). 13C NMR
(125.77 MHz, CDCl3): δ 4.5, 7.6, 18.9, 79.5, 91.2, 95.6, 104.4 (t,
3
4JCP ) 3.4 Hz), 200.0 (t, JCP ) 3.8 Hz).
Preparation of Ph-Ethynyl-Dipalladium Complex/(PPh3)2-
ClPd2[CH2CC(Ct CPh)] (5a). To a dry CH2Cl2 solution (5.0 mL)
of 120 mg (0.116 mmol) of Pd2(dba)3CHCl3 and 68.7 mg (0.262
mmol) of PPh3 was added 22.0 mg (0.126 mmol) of diynylchloride
1a under nitrogen atmosphere. After 1 h at room temperature, the
reaction mixture was purified by a silica gel column (Wakogel
C-200, CH2Cl2, Rf ) 0.83), and the first yellow-orange eluent was
concentrated to give 5a (58.8 mg) in 56% isolated yield. The same
reaction was carried out in an NMR tube (82% NMR yield, after
1 h); mp 166.4–167.5 °C (dec). Anal. Calcd for C47H37ClP2Pd2 · 2/
3CH2Cl2: C 60.83, H 4.11. Found: C 60.83, H 4.13. 1H NMR
H 4.38. 1H NMR (500.16 MHz, CDCl3): δ 1.13 (s, 6H), 5.93 (dd,
3,4
J
HP
) 31.5, 2.8 Hz, 1H), 7.34–7.42 (m, 18H), 7.56–7.63 (m,
12H). 31P NMR (202.46 MHz, CDCl3): δ 31.24 (d, JPP ) 74.4
3
Hz), 32.66 (d, JPP ) 74.4 Hz). 13C NMR (125.77 MHz, CDCl3):
3
δ 18.75, 73.00 (d, 2JCP ) 3.8 Hz), 76.98 (dd,
J
CP
) 8.6, 4.8 Hz),
2,2
2,3
3
87.37 (dd,
Hz).
J
CP
) 6.2, 6.2 Hz), 99.01, 187.68 (d, JCP ) 13.4
3
(500.16 MHz, CDCl3): δ 2.18 (d, JHP ) 5.5 Hz, 2H), 6.77 (d,

280 Organometallics, Vol. 27, No. 2, 2008
Takahashi et al.
Desilylation of 3d with TBAF. A 5 mL two-necked flask
equipped with a magnetic bar was charged with 43.6 mg (0.050
mmol) of 3d and 1.0 mL of THF. The flask was degassed with
nitrogen. After the solution was stirred vigorously for 20 min, 80.0
mg (0.080–0.12 mmol) of TBAF (on silica gel, 1.0–1.5 mmol F/g
resin) under nitrogen atmosphere was added to it. Then 0.1 mL of
H2O was added to the solution. The reaction mixture was filtered
and added to pentane (200 mL) to give a light brown precipitate.
After washing with diethyl ether and pentane, the precipitate was
dried under vacuum to give a mixture of complexes 3-H and 4-H
(3.8 mg, 10%). Because of their instability, complexes 3-H and
4-H could be characterized only spectroscopically. In the case of
the NMR study, to a solution of 43.6 mg (0.050 mmol) of 3d in
0.5 mL of THF-d8 was added 80.0 mg (0.080–0.12 mmol) of TBAF
(on silica gel, 1.0–1.5 mmol F/g resin) under nitrogen atmosphere.
The reaction was monitored by 1H and 31P NMR. After 10 min at
room temperature, 3-H and 4-H were yielded (95%) in a ratio of
52:48; mp 121.7–124.3 °C (dec). 3-H: 1H NMR (500.16 MHz,
THF-d8) δ 0.8 (s, 6H), 3.0 (s, 1H), 7.30–7.39 (m, 18H), 7.68–7.77
MHz, THF-d8): δ 19.1 (s). 1H NMR (500.16 MHz, CDCl3): δ 1.7
(s, 6H), 5.6 (m, 1H), 7.34–7.41 (m, 18H), 7.65–7.77 (m, 12H). 31
P
NMR (202.46 MHz, CDCl3): δ 22.7 (s).
Acknowledgment. This work was supported in part by a
Grant-in-Aid for Scientific Research on Priority Areas (No.
15036247 and 16033243, “Reaction Control of Dynamic
Complexes”) from Ministry of Education, Culture, Sports,
Science, and Technology, Japan. Financial support has been
provided partially though a Grant-in-Aid for Scientific
Research on Priority Areas “Advanced Molecular Transfor-
mations of Carbon Resources” from MEXT. We also thank
Ms. Yoshiko Nishikawa and Mr. Shouhei Katao for as-
sistance in obtaining HRMS spectra and X-ray data, respec-
tively. This paper is dedicated to the memory of Professor
Yoshihiko Ito.
Supporting Information Available: Cif files giving X-ray
crystallographic data and PXRD patterns for complexes 3a and 5d.
This material is available free of charge via the Internet at
http://pubs.acs.org.
1
(m, 12H). 31P NMR (202.46 MHz, THF-d8): δ 19.0 (s). H NMR
(500.16 MHz, CDCl3): δ 0.8 (s, 6H), 2.7 (s, 1H), 7.34–7.41 (m,
18H), 7.65–7.77 (m, 12H). 31P NMR (202.46 MHz, CDCl3): δ 22.6
1
(s). 4-H: H NMR (500.16 MHz, THF-d8) δ 1.7 (s, 6H), 5.6 (brs,
1H), 7.30–7.39 (m, 18H), 7.68–7.77 (m, 12H). 31P NMR (202.46
OM700909K