Synthesis and catalytic properties of cationic palladium(II) and rhodium(I) complexes bearing diphosphinidinecyclobutene ligands

Article abstract of DOI:10.1016/j.jorganchem.2006.04.048

Cationic palladium(II) and rhodium(I) complexes bearing 1,2-diaryl-3,4-bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobutene ligands (DPCB-Y) were prepared and their structures and catalytic activity were examined (aryl = phenyl (DPCB), 4-methoxyphenyl (DPCB-OMe), 4-(trifluoromethyl)phenyl (DPCB-CF₃)). The palladium complexes [Pd(MeCN)₂(DPCB-Y)]X₂ (X = OTf, BF₄, BAr₄ (Ar = 3,5-bis(trifluoromethyl)phenyl)) were prepared by the reactions of DPCB-Y with [Pd(MeCN)₄]X₂, which were generated from Pd(OAc)₂ and HX in MeCN. On the other hand, the rhodium complexes [Rh(MeCN)₂(DPCB-Y)]OTf were prepared by the treatment of [Rh(μ-Cl)(cyclooctene)₂]₂ with DPCB-Y in CH₂Cl₂, followed by treatment with AgOTf in the presence of MeCN. The cationic complexes catalyzed conjugate addition of benzyl carbamate to α,β-unsaturated ketones.

Full text of DOI:10.1016/j.jorganchem.2006.04.048

Journal of Organometallic Chemistry 692 (2007) 286–294
www.elsevier.com/locate/jorganchem
Synthesis and catalytic properties of cationic palladium(II) and
rhodium(I) complexes bearing diphosphinidinecyclobutene ligands
a
a
a,
*
Rader S. Jensen a,b, Kazutoshi Umeda , Masaaki Okazaki , Fumiyuki Ozawa
,
b,1
Masaaki Yoshifuji
a
International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
b
Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
Received 14 March 2006; received in revised form 13 April 2006; accepted 24 April 2006
Available online 1 September 2006
Abstract
Cationic palladium(II) and rhodium(I) complexes bearing 1,2-diaryl-3,4-bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobutene
ligands (DPCB–Y) were prepared and their structures and catalytic activity were examined (aryl = phenyl (DPCB), 4-methoxyphenyl
(DPCB–OMe), 4-(trifluoromethyl)phenyl (DPCB–CF3)). The palladium complexes [Pd(MeCN)2(DPCB–Y)]X2 (X = OTf, BF4, BAr4
(Ar = 3,5-bis(trifluoromethyl)phenyl)) were prepared by the reactions of DPCB–Y with [Pd(MeCN)4]X2, which were generated from
Pd(OAc)2 and HX in MeCN. On the other hand, the rhodium complexes [Rh(MeCN)2(DPCB–Y)]OTf were prepared by the treatment
of [Rh(l-Cl)(cyclooctene)2]2 with DPCB–Y in CH2Cl2, followed by treatment with AgOTf in the presence of MeCN. The cationic com-
plexes catalyzed conjugate addition of benzyl carbamate to a,b-unsaturated ketones.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Cationic complex; Palladium; Rhodium; Low-coordinated phosphorus ligand; Conjugate addition to enones
1. Introduction
ing to hitherto unknown reactivity and selectivity in hydro-
amination of dienes [4], direct conversion of allylic alcohols
into N- and C-allylation products [5], (Z)-selective hydrosi-
lylation of alkynes [6], cross-coupling reactions [7], and so
on.
There has been considerable recent interest in the
coordination chemistry of low-coordinate phosphorus
compounds due to their unique electronic properties, differ-
ing significantly from common tertiary phosphine ligands
[1]. We recently found that the 1,2-diaryl-3,4-bis[(2,4,6-
tri-t-butylphenyl)phosphinidene]cyclobutenes (DPCB–Y)
shown in Chart 1 serve as particularly useful ligands [2].
Thus, while the DPCB–Y ligands structurally resemble di-
imine ligands, they possess extremely low-lying p* orbitals
located around the phosphorus, and exhibit a strong p-
acceptor property towards transition metals [3]. We have
documented that this property is useful for catalysis, lead-
In effort to further explore the coordination behavior of
this unique class of ligand and the reactivity of the resulting
compounds, we prepared in this study a series of dicationic
palladium(II) and cationic rhodium(I) complexes bearing
DPCB–Y ligands listed in Chart 1. Dicationic palla-
dium(II) complexes have proven to be efficient catalysts
for copolymerization of CO and alkenes [8] and for conju-
gate addition of C- and N-nucleophiles to a,b-unsaturated
carbonyl compounds [9,10]. For the latter catalysis, the
electron-deficient nature of the dicationic palladium center
should be of particular importance. Therefore, we have
been interested in the construction of dicationic palladium
complexes bearing DPCB–Y ligands with strong p-accept-
ing ability. As described below, DPCB–Y ligands have
*
Corresponding author. Tel.: +81 774 76 3035; fax: +81 774 76 3039.
E-mail address: ozawa@scl.kyoto-u.ac.jp (F. Ozawa).
Present address: Department of Chemistry, The University of Ala-
1
bama, Tuscaloosa, AL 35487-0336, USA.
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.04.048

R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
287
31P NMR signals appeared at d 135.7 (1a), 127.3 (1b),
and 143.1 (1c), respectively. The chemical shifts are
34–38, 28–31, and 8–12 ppm higher than that of free
DPCB–Y [3], PdMe2(DPCB–Y) [3], and [Pd(g3-allyl)-
(DPCB–Y)]OTf [5b], respectively.
Y
Y
Mes*
P
DPCB-Y ligands (L)
Y = H (DPCB)
Y = OMe (DPCB-OMe)
Y = CF3 (DPCB-CF3)
Mes* = 2,4,6-tri-t-butylphenyl
P
Mes*
2.2. Preparation of [Rh(MeCN)2(DPCB–Y)]OTf (2a–c)
and related complexes (2d,e)
1a: X = OTf; L = DPCB
1b: X = OTf; L = DPCB-OMe
1c: X = OTf; L = DPCB-CF3
1d: X = BF4; L = DPCB
1e: X = BAr4; L = DPCB
2+
P
NCMe
NCMe
Pd
Rh
(X–)2
P
Rhodium DPCB–Y complexes 2a–e were prepared from
[Rh(l-Cl)(olefin)2]2 complexes [(olefin)2 = (cyclooctene)2,
1,5-cyclooctadiene (cod), norbornadiene (nbd)] [13]. The
cyclooctene ligands of [Rh(l-Cl)(cyclooctene)2]2 were read-
ily replaced by DPCB–Y in CH2Cl2 at room temperature
to afford [Rh(l-Cl)(DPCB–Y)]2 in quantitative yields,
which were treated subsequently with AgOTf (1 equiv/
Rh) in CH2Cl2 in the presence of MeCN to give the MeCN
complexes 2a–c. On the other hand, since [Rh(l-Cl)(cod)]2
and [Rh(l-Cl)(nbd)]2 bearing diene ligands were unreactive
towards direct ligand displacement, they were treated with
DPCB–Y in the presence of AgOTf to provide
[Rh(cod)(DPCB–Y)]OTf (2d,e) and [Rh(nbd)(DPCB)]OTf
(2e). Complexes 2a–e were isolated as purple crystalline
solids by recrystallization from CH2Cl2/Et2O.
Unlike the palladium complex 1a, the rhodium analog
2a showed an MeCN proton signal in a coordination
region without broadening (d 2.35 at 20 ꢁC), suggesting
lower reactivity of 2a than 1a towards ligand exchange.
The IR spectrum displayed two mC„N bands at 2316 and
2279 cmꢀ1. The 31P NMR signal appeared at d 162.4 in
CD3CN; the chemical shift is lower than that of 1a
(135.7), 2d (152.4), and 2e (153.1). It was further noted that
the 1JRhP values are strongly dependent on trans influence:
2a (228 Hz), 2d (176 Hz), 2e (189 Hz).
+
P
P
NCMe
NCMe
2a: L = DPCB
2b: L = DPCB-OMe
2c: L = DPCB-CF3
OTf–
+
P
P
2d: diene = cod; L = DPCB
2e: diene = nbd; L = DPCB
Rh(diene)
OTf–
Chart 1. Listing of DPCB–Y ligands and cationic complexes.
been successfully coordinated with the [Pd(MeCN)2]2+
moiety, and the resulting complexes exhibit high catalytic
performance towards conjugate addition of benzyl carba-
mate to enones [11].
2. Results and discussion
2.1. Preparation of [Pd(MeCN)2(DPCB–Y)](X)2 (1a–e)
Palladium complexes having OTf as counter anions
(1a–c) were synthesized by ligand displacement of
[Pd(MeCN)4](OTf)2 with DPCB–Y in MeCN/Et2O at
room temperature. The starting complex was prepared
from Pd(OAc)2 and 2 equiv of TfOH in MeCN [12], and
then combined with DPCB–Y without isolation. Com-
plexes 1a–c were obtained as purple crystalline solids by
recrystallization from MeCN/Et2O. The DPCB complexes
having BF4 and BAr4 (Ar = 3,5-(CF3)2C6H3) anions (1d
and 1e, respectively) were similarly prepared by using the
corresponding boric acids instead of TfOH. Complexes
1a–e were identified by IR and NMR spectroscopy and/
or elemental analysis.
2.3. X-ray structures
ORTEP drawings of 1a, 2a, and 2d are given in Fig. 1.
Selected bond distances and angles are listed in Table 1.
Complex 1a adopts a twisted square planar arrangement
around palladium; the dihedral angle between the PdP2
(A) and PdN2 (G) planes is 6.78(3)ꢁ. The C„N bonds of
˚
the MeCN ligands (2.059(3) A) are somewhat shorter than
those reported for [Pd(MeCN)2(diphosphine)]2+ complexes
˚
(2.07–2.12 A) [14]. Furthermore, the Pd–P distance
3
˚
The IR spectrum of 1a exhibited two mC„N bands at
2332 and 2303 cmꢀ1; the absorption pattern was consistent
with cis arrangement of the two MeCN ligands. In the H
(2.264(1) A) is considerably shorter than that of [Pd(g -
˚
allyl)(DPCB–Y)]OTf (2.322(1), 3.326(1) A) [4].
1
It has been documented that the phenyl groups at the
1,2-positions of DPCB ligands (E and F in Fig. 1) tend
to adopt a parallel orientation with respect to the diphos-
phinidenecyclobutene skeleton (B) upon coordination [3].
This is due to the occurrence of strong p-back donation
from metal to DPCB ligand. Thus, DPCB complexes are
stabilized by the formation of a widely spread p-conjuga-
tion system including the metal, diphosphinidenecyclobu-
tene skeleton, and phenyl groups. Accordingly, dihedral
angles between the DPCB skeleton (B) and the two benzene
NMR spectrum recorded in CDCl3, the methyl proton sig-
nal of MeCN appeared as a sharp singlet (d 2.46) at
ꢀ40 ꢁC, but was significantly broadened and shifted upfield
(ca. d 2.ꢀ1) at room temperature. Because complex 1d hav-
ing BF4 anions showed a singlet in a coordination region
(d 2.39) even at room temperature, it is considered that 1a
undergoes rapid ligand exchange between MeCN and
OTfꢀ on an NMR time scale. The loss of MeCN from
the complex was observed in the solid state as well. The

288
R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
Fig. 1. X-ray structures of 1a, 2a Æ CH2Cl2, and 2d Æ (2THF). Crystal solvents, counter anions, and hydrogen atoms are omitted for clarity.
complex, in reality it is possible that p-back donation takes
Table 1
Comparison of bond distances (A) and angles (deg) for 1a, 2a, and 2d
˚
place more efficiently in 1a. Probably, dp orbital levels of
square planar complexes are not so sensitive to r-donors
on the coordination plane, and therefore the dp–pp interac-
tion is highly dependent on the Pd–P bond length. The
occurrence of strong p-back donation in 1a is also
evidenced by the purple color of this complex, which is
markedly red-shifted from the yellow color of [Pd(g3-
allyl)(DPCB–Y)]OTf.
Description
M–P
1a
2a
2d
2.264(1)
1.662(4)
1.801(3)
2.059(3)
1.128(5)
2.2251(9)
2.2260(8)
1.670(2)
1.674(2)
1.829(2)
1.822(2)
2.068(2)
2.068(2)
1.135(3)
1.133(3)
2.334(1)
2.268(1)
1.674(3)
1.671(3)
1.828(3)
1.817(3)
–
–
–
–
P@C
P–C(Mes*)
M–N
Complex 2a has distorted square planar geometry
around rhodium; the dihedral angle between the RhP2
(A) and RhN2 (G) plane is 10.33(2)ꢁ. The C„N bonds
N„C
P–M–P
N–M–N
M–N„C
84.92(5)
88.2(2)
167.9(4)
83.53(2)
86.86(8)
166.3(2)
169.9(2)
1.6(1)
88.37(6)
96.37(6)
10.33(2)
27.2(1)
82.37(4)
–
–
˚
(1.135(3), 1.133(3) A) are comparable to those of
[Rh(MeCN)2(diphosphine)]+ complexes (1.13–1.14 A)
˚
˚
[15]. The Rh–P bond lengths (2.2251(9), 2.260(8) A) are
–
˚
[A]–[B]
[A]–[C]
[A]–[D]
[A]–[G]
[B]–[E]
[B]–[F]
5.3(1)
83.9(1)
83.9(1)
6.78(3)
24.7(2)
24.7(2)
3.1(1)
90.04(9)
84.46(8)
–
20.2(2)
27.3(2)
shorter than those of 2d (2.334(1), 2.268(1) A), and this ten-
dency is consistent with the larger Rh–P coupling of 2a
than 2d (vide supra).
2.4. Reactions with active methylene compounds
23.6(1)
X-ray diffraction studies suggested the occurrence of
strong p-back bonding interaction in 1a, which possibly
leads to the highly acidic nature of the palladium center.
The Lewis acidity was further evidenced by the reactivity
towards b-diketones (Eq. (1)). Thus, treatment of 1a with
acetylacetone (2 equiv) in Et2O at room temperature
formed a cationic complex bearing an acetylacetonato
ligand (3a). The reaction proceeded in the absence of added
base, showing the solvent Et2O to be sufficiently basic.
rings (E, F) can be used as an index of the p-back donation
intensity.
As for 1a, the dihedral angle is 24.7(2)ꢁ; the value is
notably smaller than that of [Pd(g3-allyl)(DPCB–Y)]OTf
(32.2(2), 28.2(1)ꢁ). Considering the highly electron-donat-
ing nature of g3-allyl ligand as well as the weak donating
ability of MeCN, this phenomenon seems unlikely. How-
ever, because 1a has shorter Pd–P bonds than the g3-allyl

R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
289
Similarly, 1a reacted with benzoylacetone and dib-
enzoylmethane to afford the corresponding b-diketonate
complexes (3b, 3c). Complexes 3a–c were isolated as deep
red solids in 68–83% yields.
considerable recent interest because of the prominence of
such structures in natural products and medicinal chemis-
try [10,11]. Although a number of Lewis acids have been
tested as catalysts, the present system is closely related to
those using PdCl2(MeCN)2 or [Pd(MeCN)4](BF4)2 as a cat-
alyst [10a].
P
NCMe
R1
R2
2+
Pd
+
(OTf–)2
Initially, the catalytic activity of 1a–e and 2a–d was com-
pared under controlled conditions (Eq. (2)). A 1:1 mixture
of 2-cyclohexenone (4a) and CbzNH2 in toluene was trea-
ted with 1 mol% of catalyst at room temperature for
30 min, and the yield of addition product 5a was deter-
O
O
P
NCMe
1a
R1
R2
P
P
O
O
Et2O
–Et2O·HOTf
+
Pd
1
OTf–
mined by H NMR spectroscopy using anisole as an inter-
nal standard. The results are listed in Table 2. Complex 1a
having DPCB ligand and OTf anions gave 5a in 65% yield;
the product yield reached 97% in 2 h (entry 1). The reaction
was notably slower in THF and CH2Cl2 (entries 10–12),
but ran to completion after prolonged reaction time (entry
11). The reaction proceeded smoothly in the absence of sol-
vent (entry 13), and 5a was obtained in 91% yield using
only 0.1 mol% of 1a (entry 14).
3a: R1 = R2 = Me
3b: R1 = Me, R2 = Ph
3c: R1 = R2 = Ph
ð1Þ
Although b-diketones readily reacted with 1a, a- and
c-diketones proved to be unreactive. Moreover, methyl ace-
toacetate as a b-keto ester and dimethyl malonate as a b-
diester did not react with 1a. These tendencies are consistent
with the pKa values of dicarbonyl compounds [e.g, acetylac-
etone (8.8), methyl acetoacetate (10.6), dimethyl malonate
(13.5)]. On the other hand, the rhodium analogue 2a was
unreactive towards b-diketones under similar conditions.
O
O
1a (1 mol%)
+ CbzNH2
ð2Þ
room temp.
toluene
NHCbz
65% for 30 min
(97% for 2 h)
2.5. Conjugate addition of benzyl carbamate to enones
Complexes 1c (DPCB–CF3/OTf) and 1e (DPCB/BAr4)
exhibited slightly higher catalytic activity than 1a, while
1b (DPCB–OMe/OTf) and 1d (DPCB/BF4) were less
reactive (entries 2–5). The rhodium complexes 2a–d also
performed poorly (entries 6–7). In particular, diene-coordi-
nated 2d was totally inactive under the catalytic conditions
employed (entry 9). Since the cationic rhodium complex
generated in situ from [Rh(l-Cl)(DPCB)]2 and AgOTf
(1 equiv/Rh) more efficiently promoted the reaction (91%
in 8 h) than 2a (96% in 18 h, entry 6), it is considered that
the relatively low catalytic activity of 2a–d is partly due to
the inert nature of rhodium complexes towards ligand dis-
placement as compared with the palladium analogues.
Next, the catalytic performance of 1a was examined for
a variety of cyclic and acyclic enones (Table 3). All reac-
tions were conducted at room temperature without solvent.
Unlike 2-cyclohexenone (4a) (entry 1), 2-cyclepentenone
(4b) did not react (entry 2). On the other hand, acyclic
enones having methyl substituent(s) at the b-position(s)
(4c–e) successfully reacted with CbzNH2 to give the corre-
sponding addition products (5c–e) in high yields (entries 3–
5), while compound 4f bearing a phenyl-substituent at the
b-position and methyl cyclohexenyl ketone (4g) were unre-
active (entries 6 and 7).
Catalytic activity of 1a–e and 2a–e was evaluated in con-
jugate addition of benzyl carbamate (CbzNH2) to a,b-
unsaturated ketones (4). This type of reaction provides easy
access to b-amino carbonyl compounds and has received
Table 2
Relative catalytic activity for hydroamidation of cyclohexenone (4a)a
Entry
Catalyst
Solvent
Yield of 5ab (%)
1
2
3
4
5
6
7
8
9
1a
1b
1c
1d
1e
2a
2b
2c
2d
1a
1a
1a
1a
1ae
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
THF
65 (97)c
33
70
14
67
25 (96)d
17
20
0
26
46 (95)c
62
10
11
12
13
14
a
CH2Cl2
Acetone
f
–
95
(91)c
f
–
The reactions were run at room temperature for 30 min using
cyclohexenone (1 mmol), CbzNH2 (1 mmol), catalyst (1 mol%), and sol-
vent (1 mL) unless otherwise noted.
b
Determined by 1H NMR spectroscopy using anisole as an internal
3. Conclusion
standard.
c
The yield after 2 h.
The yield after 18 h.
Catalyst amount: 0.1 mol%.
The reaction was performed without solvent.
The DPCB–Y ligands were successfully introduced to
cationic palladium(II) and rhodium(I) centers bearing
MeCN ligands, and their coordination structures were
d
e
f

290
R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
Table 3
Mercury 300 spectrometer. Chemical shifts are reported in
Hydroamidation of enones with CbzNH2 catalyzed by 1aa
1
d (ppm), referenced to H (of residual protons) and 13C
Entry
1
Enone
Time (h)
0.5
Product
Yieldb (%)
95 (92)
signals of deuterated solvents as internal standards or to
the 31P signal of 85% H3PO4 as an external standard.
GLC analysis was performed on a Shimadzu GC-8A
instrument equipped with a TCD and a Silicone OV-1
column. DPCB–Y ligands were prepared as previously
reported [3].
O
O
(5a)
NHCbz
(4a)
O
2
3
3
2
No reaction
(4b)
4.2. Preparation of [Pd(MeCN)2(DPCB–Y)](X)2 (1a–e)
O
O
NHCbz
92 (79)
82 (75)
88 (87)
A typical procedure is reported for 1a. A suspension of
Pd(OAc)2 (50 mg, 0.233 mmol) in MeCN (1 mL) was stir-
red for 30 min at room temperature. To the orange solu-
tion thus prepared was added a 1.16 M solution of
trifluoromethanesulfonic acid (TfOH) in Et2O (0.38 mL,
0.446 mmol) at ꢀ20 ꢁC; the solution instantly turned yel-
low. After stirring at ambient temperature for 45 min, the
solution was concentrated to 1/4 volume. Addition of
5 mL of Et2O resulted in an orange/tan precipitate of
[Pd(MeCN)4](OTf)2, which was collected by filtration and
washed with Et2O (5 mL · 2). This product was used in
the next step without further purification.
To the solid [Pd(MeCN)4](OTf)2 were added MeCN
(2 mL), Et2O (4 mL), and DPCB (168 mg, 0.233 mmol).
The resulting purple solution was stirred for 2 h at ambient
temperature, and then concentrated to 1 mL. Addition of
Et2O (5 mL) with gentle stirring resulted in precipitation
of the desired product 1a as a purple solid. Solvent was
removed by filtration using a filter-paper-tipped cannula,
and the product was washed with Et2O (5 mL · 3) at
ꢀ20 ꢁC and dried under vacuum (236 mg, 85%). Recrystal-
lization from MeCN/Et2O gave purple crystals suitable for
X-ray crystallography (194 mg, 70%).
(4c)
(4d)
(5c)
O
O
NHCbz
4
5
6
2
0.5
24
Ph
Ph
Ph
(5d)
O
O
NHCbz
(5e)
(4e)
O
O
No reaction
No reaction
Ph
(4f)
7
24
(4g)
a
All reactions were run at room temperature using 1a (1.0 mol%), 4
(1.0 mmol), and CbzNH2 (1.0 mmol) without solvent.
b
Determined by 1H NMR spectroscopy using anisole as an internal
standard. The values in parentheses are isolated yields after silica gel
column chromatography.
Complexes 1b and 1c were similarly prepared in 65 and
52% yields, respectively. These complexes did not give sat-
isfactory elemental analysis, but their formation was
unequivocally confirmed by NMR and IR spectroscopy.
The borate complexes 1d (86%) and 1e (94%) were synthe-
sized using HBF4 and HBAr4 [16] instead of HOTf,
respectively.
examined by NMR and X-ray diffraction analysis. The pal-
ladium complexes were highly reactive towards ligand dis-
placement, and therefore exhibited high catalytic
performance towards conjugate addition of benzyl carba-
mate (CbzNH2) to enones. The observed activity was much
higher than that of PdCl2(MeCN)2, and was comparable or
slightly higher than that of [Pd(MeCN)4](BF4)2 [10a]. It has
been noted that the addition of CbzNH2 to 2-cyclohexe-
none catalyzed by [Pd(MeCN)4](BF4)2 occasionally
involves the deposition of palladium black, which causes
disproportionation of 2-cyclohexenone to give a mixture
of cyclohexanone and phenol. Conversely, DPCB–Y com-
plexes were found to be fairly stable in this catalytic system,
and gave no sign of such side reaction.
1
1a: Mp 128–130 ꢁC (dec). H NMR (CD3CN, 20 ꢁC): d
1.45 (s, 18H), 1.70 (s, 36H), 6.92 (d, J = 7.9 Hz, 4H), 7.14
(t, J = 7.8 Hz, 4H), 7.44 (t, J = 7.5 Hz, 2H), 7.78 (virtual
triplet, Japp = 2.7 Hz, 4H). 13C{1H} NMR (CD3CN,
20 ꢁC): d 31.1 (s), 34.7 (s), 36.7 (s), 40.0 (s), 120.6 (virtual
triplet, Japp = 12 Hz), 121.9 (q, J = 320 Hz, OTf), 125.7 (t,
J = 6 Hz), 128.6 (s), 129.2 (t, J = 3 Hz), 130.1 (s), 134.3 (s),
156.2 (m, J = 81, 47 Hz), 159.0 (t, J = 2 Hz), 159.7 (s),
167.0 (m, J = 51, 46 Hz). 31P{1H} NMR (CD3CN, 20 ꢁC):
d 135.7 (s). Anal. Calc. for C58H74F6N2O6P2S2Pd: C,
56.10; H, 6.01; N, 2.26. Found: C, 56.33; H, 6.08; N,
2.58%. IR (KBr): 2332, 2303 cmꢀ1 (mC„N).
4. Experimental
4.1. General considerations
1
Compound 1b: Mp 95–97 ꢁC (dec). H NMR (CD3CN,
All manipulations were carried out under a nitrogen
atmosphere using standard Schlenk techniques unless
otherwise noted. NMR spectra were recorded on a Varian
20 ꢁC): d 1.46 (s, 18H), 1.70 (s, 36H), 3.77 (s, 6H), 6.64 (d,
J = 8.8 Hz, 4H), 6.89 (d, J = 8.8 Hz, 4H), 7.80 (virtual trip-
let, Japp = 2.7 Hz, 4H). 13C{1H} NMR (CD3CN, 20 ꢁC): d

R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
291
31.2 (s), 34.6 (s), 36.8 (s), 40.1 (s), 56.6 (s), 115.9 (s), 121.3
(s), 121.5 (virtual triplet, Japp = 11 Hz), 122.1 (q,
J = 321 Hz, OTf), 125.8 (t, J = 6 Hz), 132.1 (t, J = 2 Hz),
155.0 (m, J = 72, 36 Hz), 159.2 (t, J = 2 Hz), 159.6 (s),
164.9 (t, J = 2 Hz), 167.9 (m). 31P{1H} NMR (CD3CN,
20 ꢁC): d 127.3 (s). IR (KBr): 2324, 2296 cmꢀ1 (mC„N).
Compound 1c: Mp 136–138 ꢁC (dec). 1H NMR
(CD3CN, 20 ꢁC): d 1.45 (s, 18H), 1.70 (s, 36H), 7.01 (d,
J = 8.1 Hz, 4H), 7.43 (t, J = 8.4 Hz, 4H), 7.80 (virtual trip-
let, J = 2.8 Hz, 4H). 13C{1H} NMR (CD3CN, 20 ꢁC): d
31.0 (s), 34.8 (s), 36.7 (s), 40.1 (s), 120.0 (virtual triplet,
Japp = 12 Hz), 121.9 (q, J = 320 Hz, OTf), 124.2 (q,
J = 271 Hz, CF3), 126.0 (t, J = 6 Hz), 126.9 (q, J = 4 Hz),
129.7 (t, J = 2 Hz), 132.0 (s), 133.7 (q, J = 33 Hz), 155.0
(m, J = 88, 53 Hz), 159.2 (t, J = 2 Hz), 160.0 (s), 165.7
(m, J = 50, 46 Hz). 31P{1H} NMR (CD3CN, 20 ꢁC): d
143.1 (s). IR (KBr): 2324, 2298 cmꢀ1 (mC„N).
sure. The resulting solid was recrystallized from CH2Cl2/
Et2O to give 2a as dark red crystals, suitable for X-ray dif-
fraction analysis (185 mg, 85%).
1
Compound 2a: H NMR (CD3CN, 20 ꢁC): d 1.42 (s,
18H), 1.72 (s, 36H), 6.77 (d, J = 7.8 Hz, 4H), 6.94 (t,
J = 7.5 Hz, 4H), 7.19 (t, J = 7.5 Hz, 2H), 7.64 (virtual trip-
let, Japp = 1.7 Hz, 4H). 13C{1H} NMR (CD3CN, 20 ꢁC): d
31.5 (s), 34.4 (s), 36.2 (s), 39.6 (s), 124.3 (t, J = 4 Hz), 125.9
(m), 128.0 (s), 129.6 (s), 130.7 (s), 131.7 (s), 147.7 (m,
J = 64, 35 Hz), 155.3 (s). 157.3 (s), 163.3 (m, J = 89,
10 Hz). 31P{1H} NMR (CD3CN, 20 ꢁC): d 162.4 (d,
J = 228 Hz). IR (KBr): 2316, 2279 cmꢀ1 (mC„N). Anal.
Calc. for C57H74F3N2O3P2RhS Æ CH2Cl2: C, 59.34; H,
6.52; N, 2.39. Found: C, 59.91; H, 6.55; N, 2.37%.
1
Compound 2b: H NMR (CD3CN, 20 ꢁC): d 1.44 (s,
18H), 1.73 (s, 36H), 3.68 (s, 6H), 6.48 (d, J = 9.0 Hz,
4H), 6.71 (d, J = 9.0 Hz, 4H), 7.66 (s, 4H, PAr). 13C{1H}
NMR (CD3CN, 20 ꢁC): d 31.5 (s), 34.4 (s), 36.2 (s), 39.7
(s), 56.1 (s), 115.0 (s), 124.3 (t, J = 4 Hz), 124.4 (s), 126.2
(m), 129.9 (s), 146.8 (m, J = 64, 35 Hz), 155.1 (s), 157.4
(s), 161.5 (s), 164.2 (m, J = 90, 10 Hz). 31P{1H} NMR
(CD3CN, 20 ꢁC): d 154.7 (d, J = 228 Hz). IR (KBr):
2314, 2285 cmꢀ1 (mC„N).
Compound 1d: Mp 127–129 ꢁC (dec). 1H NMR
(CD3CN, 20 ꢁC): d 1.46 (s, 18H), 1.70 (s, 36H), 6.94 (d,
J = 7.9 Hz, 4H), 7.14 (t, J = 7.9 Hz, 4H), 7.44 (t,
J = 7.5 Hz, 2H), 7.79 (virtual triplet, Japp = 2.7 Hz, 4H).
13C{1H} NMR (CD3CN, 20 ꢁC): d 31.1 (s), 34.7 (s), 36.7
(s), 40.0 (s), 120.6 (virtual triplet, Japp = 12 Hz), 125.7 (t,
J = 6 Hz), 128.6 (s), 129.2 (t, J = 3 Hz), 130.1 (s), 134.3
(s), 156.2 (m, J = 82, 47 Hz), 159.0 (t, J = 2 Hz), 159.7
(s), 167.0 (m, J = 51, 47 Hz). 31P{1H} NMR (CD3CN,
20 ꢁC): d 135.8 (s). IR (KBr): 2332, 2303 cmꢀ1 (mC„N).
Anal. Calc. for C56H74B2F8N2P2Pd: C, 60.21; H, 6.68; N,
2.51. Found: C, 60.39; H, 6.61; N, 2.53%.
1
Compound 2c: H NMR (CD3CN, 20 ꢁC): d 1.42 (s,
18H), 1.73 (s, 36H), 6.87 (d, J = 8.1 Hz, 4H), 7.24 (d,
J = 8.1 Hz, 4H), 7.65 (virtual triplet, Japp = 1.5 Hz, 4H).
13C{1H} NMR (CD3CN, 20 ꢁC): d 31.4 (s), 34.5 (s), 36.2
(s), 39.7 (s), 124.5 (t, J = 4 Hz), 124.9 (q, J = 271 Hz,
CF3), 125.4 (m), 126.5 (q, J = 3 Hz), 128.3 (s), 130.8 (q,
J = 32 Hz), 135.3 (s), 146.3 (dd, J = 63, 33 Hz), 155.6 (s),
157.4 (s), 162.9 (m). 31P{1H} NMR (CD3CN, 20 ꢁC): d
168.6 (d, J = 230 Hz). IR (KBr): 2321, 2286 cmꢀ1 (mC„N).
Anal. Calc. for C59H72F9O3N2P2RhS: C, 57.84; H, 5.92;
N, 2.29. Found: C, 57.28; H, 6.03; N, 2.20%.
1
Compound 1e: Mp 69–70 ꢁC (dec). H NMR (CD3CN,
20 ꢁC): d 1.43 (s, 18H), 1.68 (s, 36H), 6.93 (d, J = 7.7 Hz,
4H), 7.11 (t, J = 7.9 Hz, 4H), 7.39 (t, J = 7.5 Hz, 2H),
7.64 (s, 8H), 7.71 (s, 16H), 7.78 (virtual triplet,
Japp = 2.7 Hz, 4H). 13C{1H} NMR (CD3CN, 20 ꢁC): d
31.1 (s), 34.7 (s), 36.7 (s), 40.0 (s), 118.5 (qui, J = 4 Hz),
120.6 (virtual triplet, Japp = 12 Hz), 125.3 (q, J = 272 Hz,
CF3), 125.8 (t, J = 6 Hz), 128.6 (s), 129.3 (t, J = 2 Hz),
129.7 (qq, J = 32, 3 Hz), 130.1 (s), 134.3 (s), 135.4 (s),
156.4 (m, J = 81, 46 Hz), 159.0 (t, J = 2 Hz), 159.8 (s),
162.4 (q, JBC = 50 Hz; septet, JBC = 17 Hz), 167.1(m,
J = 51, 46 Hz). 31P{1H} NMR (CD3CN, 20 ꢁC): d 135.6
(s). IR (KBr): 2332, 2303 cmꢀ1 (mC„N). Anal. Calc. for
4.4. Preparation of [Rh(diene)2(DPCB–Y)]OTf (2d,e)
The preparation of 2d (diene = 1,5-cyclooctadiene) is
given as a representative example. A 25 mL Schlenk tube
was charged with [Rh(l-Cl)(cod)]2 (60 mg, 0.122 mmol),
DPCB (184 mg, 0.244 mmol) and CH2Cl2 (2 mL), forming
a homogeneous solution. After 20 min, AgOTf (65 mg,
0.253 mmol) was added, and the solution was stirred for
1 h. Removal of silver salts by filtration through a Celite-
padded glass filter, followed by evaporation of solvent
under reduced pressure provided crude product as a purple
solid, which was washed with Et2O, and then recrystallized
from THF/Et2O affording the desired complex as a dark
red crystalline solid (197 mg, 70%). Complex 2e was simi-
larly prepared from [Rh(l-Cl)(nbd)]2 in 49% yield.
C
120H98 B2F48N2P2Pd: C, 53.98; H, 3.70; N, 1.05. Found:
C, 54.08; H, 3.70; N, 1.08%.
4.3. Preparation of [Rh(MeCN)2(DPCB–Y)]OTf (2a–c)
A typical procedure is reported for 2a. To a solution of
[Rh(l-Cl)(cyclooctene)2]2 (70 mg, 0.1 mmol) in CH2Cl2
(5 mL) was added DPCB (150 mg, 0.2 mmol). After stir-
ring at ambient temperature for 2 h, solvent was removed
under reduced pressure to provide [Rh(l-Cl)(DPCB)]2 as
a black precipitate. This product was dissolved in CH2Cl2
(2 mL), then MeCN (100 lL, 2 mmol) and AgOTf
(52 mg, 0.2 mmol) were added. After stirring for 2 h, the
solution was filtered through a Celite-padded glass filter
to remove silver salts and concentrated under reduced pres-
Compound 2d: 1H NMR (CDCl3, 20 ꢁC): d 1.41 (s,
18H), 1.61 (s, 36H), 2.41 (s, 8H), 5.26 (s, 4H), 7.00 (m,
8H), 7.27 (m, 2H), 7.65 (d, J = 2.4 Hz). 13C{1H} NMR
(CDCl3, 20 ꢁC): d 30.4 (s), 31.1 (s), 34.5 (s), 35.4 (s), 39.5
(s), 96.3 (m), 121.0 (q, J = 321 Hz, OTf), 122.0 (d,
J = 5 Hz), 124.9 (t, J = 4.1 Hz), 128.4 (m), 128.6 (s),
129.4 (s), 131.4 (s), 150.8 (dd, J = 59, 32 Hz), 154.8 (s),

292
R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
155.6 (s), 169.6 (m). 31P{1H} NMR (CDCl3, 20 ꢁC): d 152.4
(d, J = 176 Hz). Anal. Calc. for C61H80F3O3P2RhS: C,
65.70; H, 7.23. Found: C, 65.55; H, 7.23%.
6 Hz), 120.5 (q, J = 319 Hz, OTf), 124.0 (t, J = 5 Hz),
128.0 (s), 129.1 (s), 128.6 (s), 132.2 (s), 153.1 (m, J = 64,
37 Hz), 157.1 (s), 158.4 (s), 167.6 (m), 186.2 (t, J = 3 Hz).
31P{1H} NMR (CDCl3, 20 ꢁC): d 138.3 (s). Anal. Calc.
for C58H75F3O5P2SPd Æ C4H10O: C, 62.91; H, 7.24. Found:
C, 62.81; H, 7.05%.
Compound 2e: 1H NMR (CDCl3, 20 ꢁC): d 1.43 (s,
18H), 1.61 (s, 36H), 1.74 (s, 2H), 4.10 (m, 2H), 5.11 (m,
4H), 6.76 (d, J = 7.8 Hz, 4H), 6.94 (t, J = 7.8 Hz, 4H),
7.24 (t, J = 7.5 Hz, 2H), 7.62 (virtual triplet, Japp = 1.2 Hz,
4H). 13C{1H} NMR (CDCl3, 20 ꢁC): d 31.2 (s), 33.5 (s),
35.5 (s), 38.6 (s), 53.0 (q, J = 2 Hz), 67.6 (q, J = 4 Hz),
75.0 (q, J = 13 Hz), 121.0 (q, J = 321 Hz, OTf), 123.3
(m), 123.7 (t, J = 4 Hz), 128.3 (s), 128.6 (s), 129.1 (s),
131.4 (s), 151.6 (m, J = 60, 34 Hz), 154.9 (s). 156.6 (s),
173.2 (m). 31P{1H} NMR (CDCl3, 20 ꢁC): d 153.1 (d,
J = 189 Hz). Anal. Calc. for C60H76F3O3P2RhS: C, 65.56;
H, 6.97. Found: C, 65.75; H, 7.04%.
1H NMR (CDCl3, 20 ꢁC): d 1.48 (s, 9H), 1.50 (s, 9H), 1.68
(s, 9H), 1.69 (s, 9H), 1.70 (s, 9H), 1.71 (s, 9H), 2.21 (s, 3H),
6.29 (s, 1H), 6.84 (d, J = 7.7 Hz, 2H), 6.97 (d, J = 8.1 Hz,
2H), 7.06 (dt, J = 7.7, 2.4 Hz, 4H), 7.24 (t, J = 7.3 Hz,
2H), 7.35 (t, J = 7.5 Hz, 2H), 7.45 (t, J = 7.5 Hz, 1H), 7.52
(dd, J = 8.4, 1.3 Hz, 2H), 7.68 (d, J = 4.4 Hz, 2H), 7.73 (d,
J = 4.4 Hz, 2H).
Compound 3b: 13C{1H} NMR (CD2Cl2, 0 ꢁC): d 28.0
(dd, J = 10, 3 Hz), 31.2 (s), 31.2 (s), 34.0 (s), 34.1 (s),
36.0 (s), 36.1 (s), 39.0 (d, J = 1 Hz), 39.2 (d, J = 2 Hz),
97.3 (s), 118.4 (dd, J = 16, 1 Hz), 119.3 (dd, J = 16,
1 Hz), 120.7 (q, J = 320 Hz, OTf), 124.1 (t, J = 11 Hz),
127.5 (s), 128.0 (dd, J = 6, 1 Hz), 128.2 (dd, J = 7, 1 Hz),
128.6 (m), 129.1 (s), 129.1(s), 129.3 (s), 132.3 (s), 132.3
(dd, J = 13, 4 Hz), 135.8 (dd, J = 10, 4 Hz), 152.7 (dd,
J = 31, 25 Hz), 153.5 (dd, J = 31, 26 Hz), 157.2 (d,
J = 4 Hz), 157.5 (d, J = 4 Hz), 158.2 (d, J = 2 Hz), 158.5
(d, J = 2 Hz), 166.5 (dd, J = 64, 23 Hz), 167.8 (dd,
J = 64, 23 Hz), 177.6 (d, J = 3 Hz), 188.6 (d, J = 5 Hz).
31P{1H} NMR (CDCl3, 20 ꢁC): d 137.9 (d, J = 22 Hz),
140.2 (d, J = 22 Hz). Anal. Calc. for C63H77F3O5P2SPd:
C, 64.58; H, 6.62. Found: C, 64.50; H, 6.61%.
4.5. Preparation of [Pd(b-diketonato)(DPCB)]OTf
(3a–c)
A typical procedure is reported for 3a. To a suspension
of 1a (50 mg, 0.040 mmol) in Et2O (3 mL) was added acet-
ylacetone (8.2 lL, 80 lmol) at room temperature. The mix-
ture was stirred for 12 h, and solvent was removed by
filtration, giving 3a as a deep red solid. The product was
washed with Et2O and dried under vacuum (37 mg, 83%).
Complexes 3b (81%) and 3c (68%) were similarly prepared
using benzoylacetone and dibenzoylmethane instead of
acetylacetone, respectively.
Compound 3a: 1H NMR (CDCl3, 20 ꢁC): d 1.47 (s,
18H), 1.67 (s, 36H), 2.05 (s, 6H), 5.61 (s, 1H), 6.79 (d,
J = 8.4 Hz, 4H), 7.03 (t, J = 7.8 Hz, 4H), 7.32 (t,
J = 7.8 Hz, 2H), 7.66 (virtual triplet, Japp = 2.2 Hz, 4H).
13C{1H} NMR (CD2Cl2, 0 ꢁC): d 27.1 (t, J = 7 Hz), 31.2
(s), 34.0 (s), 36.0 (s), 39.0 (s), 100.6 (s), 119.1 (dd, J = 8,
Compound 3c: 1H NMR (CDCl3, 20 ꢁC): d 1.47 (s,
18H), 1.68 (s, 36H), 6.90 (s, 1H), 6.95 (d, J = 8.4 Hz,
4H), 7.06 (t, J = 8.0 Hz, 4H), 7.27 (t, J = 7.8 Hz, 4H),
7.34 (t, J = 7.2 Hz, 2H), 7.46 (tt, J = 7.4, 1.3 Hz, 2H),
7.60 (dd, J = 8.4, 1.5 Hz, 4H), 7.71 (virtual triplet,
Japp = 2.2 Hz, 4H). 13C{1H} NMR (CD2Cl2, 0 ꢁC): d 15.4
Table 4
Crystallographic data for 1a, 2a Æ CH2Cl2, and 2d Æ (2THF)
1a
2a Æ CH2Cl2
2d Æ (2THF)
Color
Red
Red
Red
Habit
Block
Block
Block
Crystal size (mm)
Formula
Fw
0.25 · 0.25 · 0.25
0.40 · 0.30 · 0.20
C58H76RhCl2F3N2O3P2S
1174.02
10.767(4)
17.705(7)
17.991(6)
113.857(4)
90.402(3)
105.877(4)
2989.9(18)
0.40 · 0.13 · 0.13
C69H96RhF3O5P2S
1259.37
14.399(6)
14.543(5)
17.349(6)
76.936(16)
74.875(16)
77.592(17)
3369(2)
C
58H74PdF6N2O6P2S2
1241.65
25.567(8)
14.757(4)
18.345(6)
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
120.6824(9)
90
5953(3)
3
˚
Volume (A )
ꢀ
ꢀ
Crystal system
C2/c (No. 15)
P1 (No. 2)
P1 (No. 2)
Space Group
Monoclinic
Triclinic
Triclinic
Z
4
2
2
h Range (ꢁ)
3.05–27.48
23250
6784 [Rint = 0.0564]
99.4%
1.113
3.06–27.48
24095
13139 [Rint = 0.0249]
96.0%
0.989
3.05–27.48
27326
14713 [Rint = 0.0318]
95.2%
1.091
Reflections collected
Independent reflections
Completeness to h
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
R1 = 0.0643, wR2 = 0.1811
R1 = 0.0719, wR2 = 0.1867
R1 = 0.0442, wR2 = 0.1193
R1 = 0.0481, wR2 = 0.1235
R1 = 0.0571, wR2 = 0.1521
R1 = 0.0678, wR2 = 0.1610

R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
(d) M. Yoshifuji, J. Synth. Org. Chem. 61 (2003) 1116;
293
(s), 31.0 (s), 34.1 (s), 36.2 (s), 39.2 (s), 65.9 (s), 94.5 (s),
118.6 (dd, J = 9, 6 Hz), 120.5 (q, J = 319 Hz, OTf), 124.2
(t, J = 5 Hz), 124.7 (d, J = 11 Hz), 127.6 (s), 127.9 (s),
128.6 (s), 128.7 (s), 129.1 (s), 129.3 (s), 128.2 (s), 128.3
(s), 132.4 (s), 133.5 (br), 136.6 (t, J = 7 Hz), 153.1 (m,
J = 64, 36 Hz), 157.5 (s), 158.3 (s), 158.4 (s), 166.9 (m),
180.1 (s). 31P{1H} NMR (CDCl3, 20 ꢁC): d 139.2 (s). Anal.
Calc. for C68H79F3O5P2SPd: C, 66.20; H, 6.45. Found: C,
66.02; H, 6.48%.
(e) M. Yoshifuji, Pure Appl. Chem. 77 (2005) 2011.
[2] F. Ozawa, M. Yoshifuji, C.R. Chimie 7 (2004) 747.
[3] F. Ozawa, S. Kawagishi, T. Ishiyama, M. Yoshifuji, Organometallics
23 (2004) 1325.
[4] T. Minami, H. Okamoto, S. Ikeda, R. Tanaka, F. Ozawa,
M. Yoshifuji, Angew. Chem., Int. Ed. 40 (2001) 4501.
[5] (a) F. Ozawa, H. Okamoto, S. Kawagishi, S. Yamamoto, T. Minami,
M. Yoshifuji, J. Am. Chem. Soc. 124 (2002) 10968;
(b) F. Ozawa, T. Ishiyama, S. Yamamoto, S. Kawagishi,
H. Murakami, M. Yoshifuji, Organometallics 23 (2004) 1698;
(c) H. Murakami, T. Minami, F. Ozawa, J. Org. Chem. 69 (2004)
4482;
4.6. Catalytic addition of benzyl carbamate to enones
(d) H. Murakami, Y. Matsui, F. Ozawa, M. Yoshifuji, J. Organomet.
Chem., 691 (2006) 3151.
A 10 mL Schlenk tube was charged with benzyl carba-
mate (CbzNH2, 151 mg, 1 mmol), toluene (1 mL),
2-cyclohexenone (96 mg, 1 mmol), and anisole (30 lL) as
an internal reference. After stirring the mixture for 5 min,
catalyst (0.01 mmol) was added. For screening reactions,
[6] (a) H. Katayama, M. Nagao, T. Nishimura, Y. Matsui, K. Umeda,
K. Akamatsu, T. Tsuruoka, H. Nawafune, F. Ozawa, J. Am. Chem.
Soc. 127 (2005) 4350;
(b) M. Nagao, K. Asano, K. Umeda, H. Katayama, F. Ozawa,
J. Org. Chem. 70 (2005) 10511.
[7] (a) K. Toyota, K. Masaki, T. Abe, M. Yoshifuji, Chem. Lett. (1995)
221;
1
conversion was determined at 30 min by H NMR. For
reactions in which the product was isolated, after comple-
tion of the reaction, solvent (if used) was removed in vacuo,
and the crude product was purified by flash chromatogra-
phy on silica gel. For reactions that were run to comple-
tion, reaction progress was monitored by GLC or 1H
NMR using anisol as an internal standard. The addition
products (5a, 5b–e) are known compounds [10a].
(b) A.S. Gajare, K. Toyota, M. Yoshifuji, F. Ozawa, Chem.
Commun. (2004) 1994;
(c) A.S. Gajare, K. Toyota, M. Yoshifuji, F. Ozawa, J. Org. Chem.
69 (2004) 6504;
(d) A.S. Gajare, R.S. Jensen, K. Toyota, M. Yoshifuji, F. Ozawa,
Synlett (2005) 144;
(e) R.S. Jensen, A.S. Gajare, K. Toyota, M. Yoshifuji, F. Ozawa,
Tetrahedron Lett. 46 (2005) 8645.
[8] A. Sen, Catalytic Synthesis of Alkene–Carbon Monoxide Coply-
mers and Coologimers, Kluwer Academic Publishers, Dordrecht,
2003.
4.7. X-ray diffraction analysis
[9] (a) T. Nishikata, Y. Yamamoto, N. Miyaura, Angew. Chem., Int.
Ed. 42 (2003) 2768;
Single crystals of 1a, 2a, and 2d were obtained by slow
diffusion of Et2O into MeCN, CH2Cl2, and THF solutions
of those complexes. The intensity data were collected on a
Rigaku Mercury CCD diffractometer at 173 K with graph-
(b) T. Nishikata, Y. Yamamoto, N. Miyaura, Organometallics 23
(2003) 4317;
(c) T. Nishikata, Y. Yamamoto, N. Miyaura, Chem. Lett. 32 (2003)
752;
(d) L. Kelin, H.K. Kuok, Chem. Commun. (2003) 1132;
(e) T. Nishikata, Y. Yamamoto, N. Miyaura, Chem. Commun.
(2004) 1822;
(f) T. Nishikata, Y. Yamamoto, N. Miyaura, Chem. Lett. 34 (2005)
720;
˚
ite-monochromated Mo Ka radiation (k = 0.71070 A).
The structures were solved by DIRDIF99 [17a] and refined
by full-matrix least-squares procedures on F2 for all reflec-
tions (SHELXL-97) [17b]. All hydrogen atoms were placed
using AFIX instructions, while other atoms were refined
anisotropically. Crystallographic data for the structural
analysis have been deposited with the Cambridge Crystal-
lographic Center: CCDC No. 600047 (1a), No. 600048
(2a Æ CH2Cl2), and No. 600049 (2d Æ (2THF)). The sum-
mary is listed in Table 4.
(g) T. Nishikata, Y. Yamamoto, I.D. Gridnev, N. Miyaura,
Organometallics 24 (2005) 5025.
[10] (a) M.J. Gaunt, J.B. Spencer, Org. Lett. 3 (2001) 25;
(b) K. Takasu, N. Nishida, M. Ihara, Synlett 10 (2004) 1844;
(c) W.J. Li, X.F. Lin, J. Wang, G.L. Li, Y.G. Wang, Synlett 13
(2005) 2003.
[11] (a) S. Kobayashi, K. Kakumoto, M. Sugiura, Org. Lett. 4 (2002)
1319;
Acknowledgement
(b) L.W. Xu, C.G. Xia, Synthesis 13 (2004) 2191;
(c) T.C. Wabnitz, J.B. Spencer, Tetrahedron Lett. 43 (2002) 3891;
(d) T.C. Wabnitz, J.B. Spencer, Org. Lett. 5 (2003) 2141;
(e) L.W. Xu, C.G. Xia, J.W. Li, S.L. Zhou, Synlett 14 (2003) 2246;
(f) L.W. Xu, C.G. Xia, X.X. Hu, Chem. Comm. 20 (2003) 2570;
(g) T.C. Wabnitz, J.Q. Yu, J.B. Spencer, Synlett 7 (2003) 1070;
(h) C. Palomo, M. Oiarbide, R. Halder, M. Kelso, E. Gomez-
Bengoa, J.M. Garcia, J. Am. Chem. Soc. 126 (2004) 9188;
(i) L.W. Xu, C.G. Xia, Tetrahedron Lett. 45 (2004) 4507;
(j) T.C. Wabnitz, J.Q. Yu, J.B. Spencer, Chem. Eur. J. 10 (2004)
484.
This work was supported by Grant-in-Aid for Scientific
Research on Priority Areas (No. 14078222, ‘‘Reaction
Control of Dynamic Complexes’’) from the Ministry of
Education, Culture, Sports, Science and Technology,
Japan.
References
[12] S. Murata, Y. Ido, Bull. Chem. Soc. Jpn. 67 (1994) 1746.
[13] (a) A. van der Ent, A.L. Onderdelinden, Inorg. Synth. 28 (1990)
90;
[1] (a) F. Mathey, Angew. Chem., Int. Ed. 42 (2003) 1578;
(b) L. Weber, Angew. Chem., Int. Ed. 41 (2002) 563;
(c) M. Doux, A. Moores, N. Mezailles, L. Ricard, Y. Jean,
P. Le Floch, J. Organomet. Chem. 690 (2005) 2407;
(b) G. Giordano, R.H. Crabtree, Inorg. Synth. 28 (1990) 88;
(c) E.W. Abel, J. Chem. Soc. A (1971) 3696.

294
R.S. Jensen et al. / Journal of Organometallic Chemistry 692 (2007) 286–294
[14] (a) K. Mikami, K. Aikawa, Y. Yusa, M. Hatano, Org. Lett. 4 (2002)
91;
(c) T.A. Betley, J.C. Peters, Angew. Chem., Int. Ed. 42 (2003)
2385.
(b) C. Bianchini, H.M. Lee, A. Meli, W. Oberhauser, F. Vizza,
P. Bruggeller, R. Haid, C. Langes, Chem. Commun. (2000) 777;
(c) E. Lindner, M. Schmid, J. Wald, J.A. Queisser, M. Geprags,
P. Wegner, C. Nachtigal, J. Organomet. Chem. 602 (2000) 173;
(d) D. Drago, P.S. Pregosin, Organometallics 21 (2002) 1208.
[15] (a) H. Wang, R.J. Barton, B.E. Robertson, Acta Crystallogr., Sect.
C: Cryst. Struct. Commun. 47 (1991) 504;
[16] (a) S.R. Bahr, P. Boudjouk, J. Org. Chem. 57 (1992) 5545;
(b) M. Brookhart, B. Grant, A.F. Volpe Jr., Organometallics 11
(1992) 3920.
´
[17] (a) P.T. Beurskens, G. Beurskens, R. de Gelder, S. Garcıa-Granda,
R.O. Gould, R. Israel, J.M.M. Smits. The DIRDIF99 Program System.
Technical Report of the Crystallography Laboratory, University of
Nijmegen, The Netherlands, 1999.;
(b) C. Carcedo, A. Dervisi, I.A. Fallis, L. Ooi, K.M.A. Malik, Chem.
Commun. (2004) 1236;
(b) G.M. Sheldrick, SHELXL-97, Programs for Refining X-ray Crystal
Structures, University of Go¨ttingen, 1997.