Stereoselective ligand-exchange reaction of planar-chiral cyclopentadienyl-ruthenium complexes: Thermodynamic control of configuration at a stereogenic metal center

Article abstract of DOI:10.1039/b314859a

The reaction of planar-chiral cyclopentadienyl-ruthenium complexes with Bu₄NI resulted in the formation of lodo complexes with high diastereoselectivity (up to >99%de). The stereochemistry of the ruthenium center in the starting material did not influence the diastereoselectivity of the products. Epimerization of a diastereomerically pure sample gave a mixture of two diastereomers in the same ratio as with the ligand-exchange reaction, suggesting that the selectivity is determined by the difference in thermodynamic stability between the diastereomeric pair of iodo complexes. The ratio of the products depends on the nature of the substituent on the cyclopentadienyl ring and P ligands on the ruthenium atom. A combination of small substituents on the cyclopentadienyl group and small P ligands with strong electron-donating ability favored the formation of 2-1. The bulkiness of the substituents on the cyclopentadienyl group or of the P ligands, and low electron-donating ability of the P ligands increased the ratio of 2-II complexes to 2-I isomer.

Full text of DOI:10.1039/b314859a

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Stereoselective ligand-exchange reaction of planar-chiral
cyclopentadienyl–ruthenium complexes: thermodynamic control of
configuration at a stereogenic metal center
Yuji Matsushima, Kiyotaka Onitsuka and Shigetoshi Takahashi*
The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki,
Osaka 567-0047, Japan. E-mail: takahashi@sanken.osaka-u.ac.jp
Received 18th November 2003, Accepted 23rd December 2003
First published as an Advance Article on the web 20th January 2004
The reaction of planar-chiral cyclopentadienyl–ruthenium complexes with Bu4NI resulted in the formation of iodo
complexes with high diastereoselectivity (up to >99%de). The stereochemistry of the ruthenium center in the starting
material did not influence the diastereoselectivity of the products. Epimerization of a diastereomerically pure sample
gave a mixture of two diastereomers in the same ratio as with the ligand-exchange reaction, suggesting that the
selectivity is determined by the difference in thermodynamic stability between the diastereomeric pair of iodo
complexes. The ratio of the products depends on the nature of the substituent on the cyclopentadienyl ring and P
ligands on the ruthenium atom. A combination of small substituents on the cyclopentadienyl group and small P
ligands with strong electron-donating ability favored the formation of 2-I. The bulkiness of the substituents on the
cyclopentadienyl group or of the P ligands, and low electron-donating ability of the P ligands increased the ratio of
2-II complexes to 2-I isomer.
Introduction
Results and discussion
Considerable attention has been attracted on chiral half-
sandwich transition-metal complexes, which have been
described as promising catalysts for novel asymmetric organic
syntheses.1 Although most of them have chiral P- or N-ligands,
and/or π-ligands with chiral substituents,2 two other types of
chiral complexes have recently been the subject of special inter-
est; i.e., a metal-centered chiral complex and a planar-chiral
complex. Metal-centered chirality is induced by the coordin-
ation of three different kinds of ligands other than the cyclo-
pentadienyl (Cp) group in CpML3-type complexes, and many
examples of such chiral complexes can be found in the liter-
ature.3 However, the successful application of these complexes
as effective asymmetric catalysts is still limited due to configur-
ational lability at the metal center. Therefore, efficient control
of the geometry around the metal center is important for
the development of new asymmetric catalytic reactions. On the
other hand, planar chirality is generated by coordination
of unsymmetrically substituted π-ligands to metal atoms.4
Although extensive studies have been done on planar-chiral Cp
complexes, most have focused on early transition-metal com-
plexes. Since Cp complexes of late-transition metals often show
interesting reactivities, planar-chiral versions have great poten-
tial as novel asymmetric catalysts.5,6
Treatment of diastereomerically pure ruthenium complex
[(η5,η1-2,4-Me2-C5H2CO2CH2CH2PPh2)Ru(PMe3)(MeCN)]-
[PF6] (1a-I), the configuration of which is SCpRRu/RCpSRu,† with
Bu4NI in refluxing methanol for 3 h gave iodo complex (η5,η1-
2,4-Me2-C5H2CO2CH2CH2PPh2)Ru(PMe3)I (2a) in 94% yield
(Scheme 1).10 Although this ligand-exchange reaction can pos-
sibly form two pairs of diastereomers (SCpRRu/RCpSRu and SCp
-
SRu/RCpRRu),† 31P NMR of 2a clearly showed that the product
consisted of a single diastereomer 2a-I. The configuration of
complex 2a-I was unequivocally determined to be SCpRRu/RCp
-
SRu by X-ray crystallography, with a priority of I > CpЈ >
CH2PPh2 (anchor) > PMe3.† The molecular structure of com-
plex 2a-I is shown in Fig. 1. When complex 1a-II, which is a
diastereomer of 1a-I, was used as a starting material, the same
We have been studying the planar-chiral Cp complexes of
late-transition metals using trisubstituted cyclopentadiene
(CpЈH).7 Recently, we prepared planar-chiral CpЈ–Ru com-
plexes possessing an anchor phosphine ligand to prevent
rotation of the CpЈ ring8 and observed the highly selective
induction of metal-centered chirality in the reaction of
[(CpЈCO2CH2CH2PPh2)Ru(MeCN)2][PF6] with
P
ligands.9
Since multi-step ligand-exchange reactions often play fund-
amental roles in a single catalytic cycle, it would be interesting
to determine if the geometry at the metal center is maintained
in such reactions. We report here the stereochemistry at the
metal center in ligand-exchange reactions of planar-chiral
CpЈ–Ru complexes, which have a stereogenic metal center, with
an iodonium ligand.
Since racemic mixtures were used as starting materials in this
work, all of the complexes presented here consist of a pair of
enantiomers. However, all stereostructures are shown with a
planar chirality of SCp for clarity.
Scheme 1 Reagents and conditions: i, 3 eq of Bu4NI, MeOH, reflux,
3 or 24 h.
† The assignments for the configuration at a metal center (R or S) in
complexes with triphenylphosphine and triphenylphosphite are oppos-
ite those of trimethylphosphine derivatives with the same conformation
due to the difference in the priorities of the anchor phosphine ligand
and the P ligands.
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
D a l t o n T r a n s . , 2 0 0 4 , 5 4 7 – 5 5 3
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Table 1 Reactions of complexes 1-I and/or 1-II with Bu4NI
Entry
Substrate
Product
Yield (%)
%dea, b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1a-I
2a
2a
2a
2b
2c
2d
2d
2e
2e
2f
2g
2g
2h
2i
94
92
91
81
90
89
85
90
92
91
67
65
57
59
>99 (I)
>99 (I)
>99 (I)
>99 (I)
66 (II)c
30 (I)
1a-II
1a-I ϩ 1a-II (50:50)
1b-II
1c-II
1d-II
1d-I ϩ 1d-II (25:75)
30 (I)
1e-II
76 (I)
76 (I)
>99 (II)
68 (II)
68 (II)
32d
1e-I ϩ 1e-II (10:90)
1f-II
1g-I
1g-II
1h-II
1i-II
>99 (II)
a Determined by 31P-NMR spectra. b The symbol in parentheses indi-
cates the configuration of the major products as determined by X-ray
crystallography. c The configuration was determined by NOE spectra.
d The configuration could not be determined.
Fig. 2 Molecular structure of complex 2b-I. Hydrogen atoms are
omitted for clarity.
differential NOE spectra gave good information regarding
stereochemistry. The NOE signals of two CpЈ protons were
observed by irradiation of the t-Bu signal of the major isomer,
while irradiation of the t-Bu signal of the minor isomer gave
NOE signals not only of two CpЈ protons but also of PMe3
protons. These data clearly suggest that the t-Bu group and
PMe3 are close to each other in the minor product compared to
the major product, which means that the major isomer is 2c-II
and the minor one is 2c-I. It may be of interest that the con-
figuration of the major product 2c-II is opposite those of 2a-I
and 2b-I.
Upon treatment of complex 1d-II bearing triphenyl-
phosphine instead of trimethylphosphine, two diastereomers
2d-I and 2d-II were formed with 30%de (entry 6). While the
reaction of complex 1e-II produced an iodo complex (2e) with
76%de (entry 8), the reaction of complex 1f-II gave an iodo
complex (2f-II) as a single diastereomer (entry 10). Single crys-
tals of complexes 2d-I and 2e-I as well as complex 2f-II were
obtained by recrystallization from dichloromethane-methanol.
The 1H NMR spectra clearly showed that the crystals consist of
the major products. Thus, the stereochemistry of these major
products was also determined by X-ray analysis. Figs. 3, 4
and 5 show the molecular structures of 2d-I, 2e-I and 2f-II,
respectively. As seen in the trimethylphosphine complexes, the
configuration of the major complex of the t-Bu analogue is
different from those of the other complexes. The reaction of
complex 1g-I which contains triphenylphosphite proceeded
slowly, and a longer reaction time (24 h) was required for
complete consumption of the starting material to give an
iodo complex (2g-II) in 65% yield with 68%de (entry 11). The
diastereoselectivity of the reaction using complex 1h-II was not
high (32%de, entry 13), and the stereochemistry of the products
could not be determined. In contrast, a single diastereomer
(2i-II) was produced in the reaction of complex 1i-II (entry 14).
Since single crystals of complexes 2g-II and 2i-II,the former of
Fig. 1 Molecular structure of complex 2a-I. Hydrogen atoms are
omitted for clarity.
complex 2a-I was obtained as a sole product in 92% yield. A
similar reaction of a 1 : 1 mixture of 1a-I and 1a-II also gave
complex 2a-I selectively. These results suggest that the stereo-
chemistry of the ruthenium center in the starting material does
not influence the stereoselectivity of the product, and are in
sharp contrast to those for the similar reaction of [CpЉR*Ru-
(CO)(PPh3)(MeCN)]PF6 (CpЉ = η5-C5H4, R* = neomenthyl) to
CpЉR*Ru(CO)(PPh3)I, which proceeded with a retention of
configuration at the metal center.11
To examine the substituent effect on the CpЈ ring and the P
ligands, we performed reactions with several ruthenium com-
plexes. Representative results are given in Table 1, along with
the results described above. The reaction of complex 1b-II,
which has a phenyl group at the 4-position on the CpЈ ring, also
gave an iodo complex (2b-I) as a single diastereomer (entry 4),
the configuration of which was determined by X-ray analysis
(Fig. 2). In contrast, the reaction of t-Bu analogue 1c-II pro-
duced an iodo complex (2c) that contained two diastereomers
in a ratio of 83 : 17 (66%de, entry 5). Since no good crystals of
the products were obtained, we could not determine the stereo-
chemistry of the products by X-ray crystallography. However,
1
which was confirmed to consist of the major product by H
NMR, were obtained, their configurations were also deter-
mined by X-ray analysis (Figs. 6 and 7). In these reactions, the
selectivity of the products is also independent of the stereo-
chemistry of the ruthenium center in the starting complexes
(entries 7, 9 and 12).
When a diastereomerically pure sample of 2d-I was dissolved
in CDCl3, slow epimerization at the Ru center took place to give
a diastereomixture of 2d-I and 2d-II in a ratio of 65:35, which
is the same as the selectivity of the reaction from 1d to 2d
D a l t o n T r a n s . , 2 0 0 4 , 5 4 7 – 5 5 3
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Fig. 3 Molecular structure of complex 2d-I. Hydrogen atoms are
omitted for clarity.
Fig. 5 Molecular structure of complex 2f-II. Hydrogen atoms are
omitted for clarity.
Fig. 6 Molecular structure of complex 2g-II. Hydrogen atoms are
omitted for clarity.
Fig. 4 Molecular structure of complex 2e-I. Hydrogen atoms are
omitted for clarity.
(Scheme 2). Similar phenomena were observed for complexes
2c-I/2c-II, 2e-I/2e-II, and 2g-I/2g-II. These data clearly suggest
that equilibrium between the diastereomers 2-I and 2-II is estab-
lished in solution and the ratio is under thermodynamic con-
trol. Although no epimerization was observed for complexes
2a-I, 2b-I, 2f-II, and 2i-II, it seems reasonable to suppose that
the equilibrium strongly favors a particular isomer due to the
large difference in thermodynamic stability between the two
diastereomers of these complexes. This is consistent with the
fact that the selectivity of the products does not at all depend
on the configuration of the starting complexes. To obtain
information on the mechanism, we examined the epimerization
of pure isomer 2d-I in the presence of 10 equivalents of PPh3 or
Bu4NI. However, no effect on the rate of epimerization was
observed, suggesting that the rate-determining step is neither
dissociation of PPh3 or IϪ to generate a 16e species nor their
coordination to the Ru atom via an associative mechanism.
Table 1 clearly shows that the selectivity of the products is
influenced by both the substituent at the 4-position on the CpЈ
ring and the P ligand on the Ru atom. The selectivity of 2-II
increased in the order Ph < Me < t-Bu for the substituent at the
Fig. 7 Molecular structure of complex 2i-II. Hydrogen atoms are
omitted for clarity.
4-position on the CpЈ ring, suggesting that steric repulsion
between the substituent and the P ligand decreases the stability
of 2-I. Although it may seem strange that the steric repulsion of
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Table 2 Selected bond distances (Å) and angles (Њ) for complexes 2a-I, 2b-I, 2d-I, 2e-I, 2f-II, 2g-II, and 2i-II
2a-I
2b-I
2d-I
2e-I
2f-II
2g-II
2i-II
Ru(1)–I(1)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–C(3)
Ru(1)–C(4)
Ru(1)–C(5)
2.7456(5)
2.307(1)
2.308(1)
2.207(4)
2.296(4)
2.255(4)
2.222(4)
2.169(4)
2.7186(6)
2.326(1)
2.317(2)
2.212(6)
2.297(5)
2.255(5)
2.241(5)
2.148(5)
2.7303(5)
2.337(1)
2.348(1)
2.180(5)
2.275(5)
2.266(5)
2.265(5)
2.183(5)
2.7475(3)
2.3489(9)
2.3799(8)
2.207(3)
2.314(3)
2.295(3)
2.302(3)
2.182(3)
2.7315(4)
2.3590(8)
2.3493(7)
2.171(3)
2.238(3)
2.275(3)
2.330(3)
2.227(3)
2.6997(3)
2.3396(7)
2.209(2)
2.164(3)
2.230(3)
2.261(3)
2.302(3)
2.218(3)
2.724(1)
2.351(2)
2.208(2)
2.167(6)
2.226(7)
2.282(7)
2.347(6)
2.240(6)
I(1)–Ru(1)–P(1)
I(1)–Ru(1)–P(2)
P(1)–Ru(1)–P(2)
92.27(3)
91.34(3)
95.02(4)
90.00(4)
87.71(4)
97.52(5)
86.72(3)
89.88(3)
100.84(5)
88.29(2)
93.92(2)
99.20(3)
87.22(2)
87.12(2)
99.59(3)
89.77(2)
92.51(2)
92.26(3)
88.19(4)
93.93(4)
90.73(6)
2.6997(3) Å, respectively. This sequence correlates with the elec-
tronic properties of P ligands. A similar tendency was found
regarding the Ru–Cl bonds of CpRuL1L2Cl complexes in the
series L1 = L2 = PPh3 > L1 = PPh3, L2 = P(OMe)3 > L1 = L2 =
P(OMe)3.14 The Ru(1)–P(2) bonds of phosphite complexes
2g-II and 2i-II are shorter than those of phosphine complexes,
due to the stronger π-acid character of phosphite.12
In summary, we have described here the highly selective
thermodynamic control of metal-centered chirality by a planar-
chiral cyclopentadienyl ligand. These results should provide
useful information for understanding the mechanism of
asymmetric reactions using planar-chiral cyclopentadienyl–
ruthenium complexes. Further studies on other ligand-
exchange reactions are now in progress.
Experimental
General
Scheme 2 Reagents and conditions: i, CDCl3, room temperature, 12 h.
All reactions were carried out under an argon atmosphere, but
the workup was performed in air. 1H, 13C, and 31P NMR spectra
were measured on JEOL JNM-LA400 and JEOL JNM-LA600
spectrometers using CDCl3 as a solvent. Chemical shifts are
given in ppm based on SiMe4 as an internal standard for 1H and
13C NMR, and 85% H3PO4 as an external standard for 31P
NMR. IR and mass spectra were taken on a Perkin-Elmer
system 2000 FT-IR and JEOL JMS-600H instrument, respect-
ively. Elemental analyses were performed by the Material
Analysis Center, ISIR, Osaka University.
the Me group is greater than that of the Ph group, this is due to
the fact that the Ph group is almost coplanar with the CpЈ ring
due to conjugation between them. In contrast, the selectivity of
2-I increased in the order P(OPh)3 < PPh3 < PMe3. Of course,
the bulkiness of the P ligands affects the selectivity, as found in
the substituent effects on the CpЈ ring. The combination of a
bulky P ligand, P(OPh)3 or PPh3, and the t-Bu group on the CpЈ
ring resulted in the selective formation of complexes 2f-II and
2i-II due to large steric repulsion in the 2-I structure.12 However,
despite the smaller cone angle of P(OPh)3 than of PPh3, 2g-II
was the major product while 2d-I was produced with 30%de.
These results suggest that electron-donating ability also plays
an important role. Less electron-donating P ligands would
stabilize 2-II, which is consistent with the highly selective form-
ation of complexes 2a-I and 2b-I. The greater donating ability
of trimethylphosphine increases the thermal stability of 2-I and
the substituents on both the CpЈ group and P ligand are too
small to show steric interaction.
Table 2 summarizes the structural parameters of seven iodo
complexes, and indicates that they are all independent of not
only the substituents on the CpЈ ring and the P ligand but also
the configuration at the metal center. Especially, the structures
of the CpЈCO2C2H4PPh2Ru skeleton are essentially identical.
The Ru(1)–C(1) and Ru(1)–C(5) bonds are slightly shorter than
the other Ru–C bonds. Similar phenomena were observed for
analogous planar-chiral CpЈ–Ru complexes with phosphine
ligands. Therefore, this is not due to the influence of the ligands
bound to the Ru atom at sites opposite the CpЈ group, but
rather to structural features of the CpЈCO2C2H4PPh2Ru
moiety.9,10,13
Ruthenium complexes 1a–1i were prepared by the method
previously reported.9 All other chemicals available com-
mercially were used without further purification.
Reaction of ruthenium complexes 1a–1c with Bu4NI.
Ruthenium complex 1 (0.10 mmol) was dissolved in methanol
(5 mL), and Bu4NI (0.10 g, 0.30 mmol) was added. After reflux
for 3 h, the solvent was removed under reduced pressure. The
residual solid was dissolved in benzene, and the solution was
placed on a silica gel column. The product was eluted with
hexane–ethyl acetate (V/V = 3/1). The solvents were evaporated
and the resulting red solid was dried in vacuo. Yield and
diastereoselectivity of the products are given in Table 1.
1
(ꢀ5:ꢀ1-2,4-Me2-C5H2CO2CH2CH2PPh2)Ru(PMe3)I (2a-I). H
NMR (400 MHz): δ 7.57–7.49 (m, 5H, Ph), 7.26–7.17 (m, 5H,
Ph), 5.12–5.03 (m, 1H, OCH2), 4.44 (s, 1H, CpЈ), 4.38 (s, 1H,
CpЈ), 3.97–3.90 (m, 1H, OCH2), 3.54–3.46 (m, 1H, CH2P), 2.62
(s, 3H, CpЈCH3), 2.51 (dt, 1H, J = 14.6, 5.4 Hz, CH2P), 2.08 (s,
3H, CpЈCH3), 1.13 (d, 9H, J = 9.0 Hz, PMe3). 13C NMR (150
MHz): δ 163.9 (C᎐O), 141.9–127.5 (Ph), 117.2 (CpЈ), 88.4 (CpЈ),
᎐
82.2 (CpЈ), 82.1 (d, J = 10 Hz, CpЈ), 76.1 (d, J = 7 Hz, CpЈ),
58.3 (d, J = 4 Hz, CH2O), 24.8 (d, J = 31 Hz, CH2P), 21.9 (d,
J = 30 Hz, PMe3), 16.2 (CpЈCH3), 14.2 (CpЈCH3). 31P NMR
(160 MHz): δ 38.4 (d, J = 42 Hz), 0.8 (d, J = 42 Hz). IR [KBr,
The Ru(1)–I(1) bond length tends to decrease in the order of
PMe3, PPh3 and P(OPh)3 analogues with the same substituent
on the CpЈ ring. Thus, the Ru(1)–I(1) bond lengths in
complexes 2a-I, 2d-I and 2g-II are 2.7456(5), 2.7303(5) and
νmax/cmϪ1]: 1704 (C᎐O). FAB MS: m/z 654 (Mϩ). Calc. for
᎐
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C25H31IO2P2Ru: C, 45.95; H, 4.78; I, 19.42%. Found: C, 45.70;
H, 4.55; I, 19.59%.
(Mϩ). Calc. for C45H39IO2P2Ru: C, 59.94; H, 4.36; I, 14.07%.
Found: C, 59.71; H, 4.11; I, 14.12%. Major product (2e-I): H
1
NMR (400 MHz): δ 7.46–6.62 (m, 30H, Ph), 5.40 (s, 1H, CpЈ),
5.09–4.99 (m, 1H, OCH2), 4.46 (s, 1H, CpЈ), 3.97–3.84 (m, 2H,
OCH2, CH2P), 2.81 (s, 3H, CpЈCH3), 2.59–2.53 (m, 1H, CH2P).
(ꢀ5:ꢀ1-2-Me-4-Ph-C5H2CO2CH2CH2PPh2)Ru(PMe3)I (2b-I).
1H NMR (400 MHz): δ 7.58–7.39 (m, 11H, Ph), 7.14–7.12 (br,
4H, Ph), 5.20–5.10 (m, 1H, OCH2), 5.06 (s, 1H, CpЈ), 4.95 (s,
1H, CpЈ), 4.09 (dt, 1H, J = 11.7, 5.1 Hz, OCH2), 3.54–3.45 (m,
1H, CH2P), 2.75 (s, 3H, CpЈCH3), 2.54 (dt, 1H, J = 14.7, 5.1 Hz,
CH2P), 0.81 (d, 9H, J = 9.3 Hz, PMe3). 13C NMR (150 MHz):
13C NMR (150 MHz): δ 167.1 (C᎐O), 152.2–121.5 (Ph), 118.0
᎐
(CpЈ), 92.7 (CpЈ), 84.6 (CpЈ), 82.6 (d, J = 9 Hz, CpЈ), 78.2 (d,
J = 15 Hz, CpЈ), 58.7 (d, J = 4 Hz, OCH2), 24.7 (d, J = 34 Hz,
PCH2), 15.6 (CpЈCH3), 13.7 (CpЈCH3). 31P NMR (160 MHz):
δ 34.0 (d, J = 36 Hz), 27.7 (d, J = 36 Hz). Minor product (2e-II):
31P NMR (160 MHz): δ 38.1 (d, J = 35 Hz), 24.9 (d, J = 35 Hz).
δ 164.0 (C᎐O), 141.8–127.5 (Ph), 126.1 (CpЈ), 117.0 (CpЈ), 90.5
᎐
(CpЈ), 79.0 (CpЈ), 77.2 (CpЈ), 58.5 (d, J = 4 Hz, CH2O), 24.5 (d,
J = 32 Hz, CH2P), 20.7 (d, J = 30 Hz, P(CH3)3), 16.6 (CpЈCH3).
31P NMR (160 MHz): δ 37.1 (d, J = 43 Hz), 0.3 (d, J = 43 Hz).
(ꢀ5:ꢀ1-2-Me-4-But-C5H2CO2CH2CH2PPh2)Ru(PPh3)I (2f-II).
1H NMR (600 MHz): δ 8.12 (br, 2H, Ph), 7.58–7.02 (m, 19H,
Ph), 6.80 (t, 2H, J = 6.6 Hz, Ph), 6.31 (br, 2H, Ph), 5.07–4.97
(m, 2H, CpЈ and OCH2), 3.98 (s, 1H, CpЈ), 3.77–3.73 (m, 1H,
OCH2), 2.98–2.93 (m, 1H, CH2P), 2.10–2.07 (m, 1H, CH2P),
1.48 (s, 9H, But), 1.37 (d, 3H, J = 1.6 Hz, CpЈCH3). 13C NMR
IR [KBr, νmax/cmϪ1]: 1715 (C᎐O). FAB MS: m/z 716 (Mϩ). Calc.
᎐
for C30H33IO2P2Ru: C, 50.36; H, 4.65; I, 17.74%. Found: C,
50.20; H, 4.55; I, 17.77%.
(ꢀ5:ꢀ1-2-Me-4-But-C5H2CO2CH2CH2PPh2)Ru(PMe3)I (2c-I
and 2c-II). IR [KBr, νmax/cmϪ1]: 1731 (C᎐O), 1715 (C᎐O). FAB
(150 MHz): δ 170.3 (C᎐O), 143.0–126.3 (Ph), 98.2 (CpЈ),
᎐
᎐
᎐
MS: m/z 696 (Mϩ). Calc. for C28H37IO2P2Ru: C, 48.35; H, 5.36;
I, 18.25%. Found: C, 48.25; H, 5.25; I, 18.34%. Major product
82.3 (d, J = 12 Hz, CpЈ), 77.2 (CpЈ), 66.9 (d, J = 9.1 Hz, CpЈ),
59.1 (d, J = 4 Hz, OCH2), 34.4 (CMe3), 30.7 (CMe3), 21.4 (d,
J = 26 Hz, PCH2), 12.1 (CpЈCH3). 31P NMR (160 MHz): δ 42.2
(d, J = 34 Hz), 19.8 (d, J = 34 Hz). IR [KBr, νmax/cmϪ1]: 1715
1
(2c-II): H NMR (400 MHz): δ 8.03–7.96 (m, 2H, Ph), 7.43–
7.33 (m, 5H, Ph), 7.26–7.21 (m, 3H, Ph), 5.01–4.87 (m, 1H,
OCH2), 4.93 (s, 1H, CpЈ), 4.53 (s, 1H, CpЈ), 3.62–3.52 (m, 1H,
OCH2), 2.88–2.75 (m, 1H, CH2P), 2.50 (dt, 1H, J = 14.1, 14.2
Hz, CH2P), 2.25 (d, 3H, J = 3.0 Hz, CpЈCH3), 1.52 (s, 9H,
But), 1.14 (d, 9H, J = 8.7, PMe3). 13C NMR (150 MHz): δ 169.3
(C᎐O). FAB MS: m/z 882 (Mϩ). Calc. for C H IO P Ru: C,
᎐
43 43
2
2
58.57; H, 4.92; I, 14.39%. Found: C, 58.55; H, 4.69; I, 14.47%.
Reaction of ruthenium complexes 1g–1i with Bu4NI. To a
methanol solution (5 mL) of ruthenium complex 3 (0.10 mmol)
was added Bu4NI (0.10 g, 0.30 mmol) and the reaction mixture
was refluxed for 24 h. After removal of the solvent under
reduced pressure, the residual solid was dissolved in benzene.
The benzene solution was placed on a silica gel column and
eluted with hexane–ethyl acetate (V/V = 3/1). The solvents were
evaporated and the resulting red solid was dried in vacuo. Yield
and diastereoselectivity of the products are given in Table 1.
(C᎐O), 141.3–127.4 (Ph), 108.8 (CpЈ), 98.3 (CpЈ), 76.0 (CpЈ),
᎐
73.9 (CpЈ), 73.7 (CpЈ), 58.7 (CH2O), 33.8 (CMe3), 31.0 (CMe3),
24.4 (d, J = 31 Hz, CH2P), 20.4 (d, J = 27 Hz, PMe3), 13.3
(CpЈCH3). 31P NMR (160 MHz): δ 26.4 (d, J = 39 Hz), Ϫ1.4 (d,
J = 39 Hz). Minor product (2c-I): 1H NMR (400 MHz): δ 7.78–
7.72 (m, 2H, Ph), 7.54–7.15 (m, 8H, Ph), 5.10–5.05 (m, 1H,
OCH2), 4.43 (s, 2H, CpЈ), 3.94–3.93 (m, 1H, OCH2), 3.66–3.54
(m, 1H, CH2P), 2.68 (s, 3H, CpЈCH3), 2.53–2.47 (m, 1H,
CH2P), 1.37 (s, 9H, But), 1.21 (d, 9H, J = 9.0, PMe3). 31P NMR
(CDCl3, 160 MHz): δ 34.2 (d, J = 42 Hz), Ϫ2.1 (d, J = 42 Hz).
(ꢀ5:ꢀ1-2,4-Me2-C5H2CO2CH2CH2PPh2)Ru[P(OPh)3]I (2g-I
and 2g-II). IR[KBr, νmax/cmϪ1]: 1722 (C᎐O), 1716 (C᎐O) cmϪ1
.
᎐
᎐
Reaction of ruthenium complexes 1d–1f with Bu4NI. To a solu-
tion of ruthenium complex 1 (0.11 mmol) in methanol (5 mL)
was added Bu4NI (0.11 g, 0.33 mmol), and the reaction mixture
was refluxed for 3 h. Resulting red precipitate was collected and
washed with methanol several times. Drying in vacuo gave red
solids. Yield and diastereoselectivity of the products are given
in Table 1.
FAB MS: m/z 888 (Mϩ). Calc. for C40H37IO5P2Ru: C, 54.13; H,
4.20; I, 14.30%. Found: C, 54.40; H, 4.21; I, 14.18%. Major
product (2g-II): 1H NMR (400 MHz): δ 7.93–7.89 (m, 2H, Ph),
7.62 (t, 2H, J = 8.1 Hz, Ph), 7.45 (br, 3H, Ph), 7.26–7.15 (m, 3H,
Ph), 7.09 (t, 6H, J = 7.3 Hz, Ph), 6.97 (t, 3H, J = 7.3 Hz, Ph),
6.88 (d, 6H, J = 8.1 Hz, Ph), 5.07–4.94 (m, 1H, OCH2), 4.96
(s, 1H, CpЈ), 3.76 (br, 1H, OCH2), 3.71 (br, 1H, CpЈ), 3.35–3.27
(m, 1H, CH2P), 2.57 (dt, 1H, J = 14.4, 4.4 Hz, CH2P), 2.44 (br,
3H, CpЈCH3), 2.29 (br, 3H, CpЈCH3). 13C NMR (150 MHz):
(ꢀ5:ꢀ1-2,4-Me2-C5H2CO2CH2CH2PPh2)Ru(PPh3)I (2d-I and
2d-II). IR [KBr, νmax/cmϪ1]: 1714 (C᎐O). FAB MS: m/z 840
δ 165.1 (C᎐O), 143.4–126.7 (Ph), 112.3 (CpЈ), 90.9 (CpЈ), 89.4
᎐
᎐
(Mϩ). Calc. for C40H37IO2P2Ru: C, 57.22; H, 4.44; I, 15.11%.
Found: C, 56.98; H, 4.18; I, 15.02%. 13C NMR (150 MHz):
δ 168.8 (C᎐O), 164.9 (C᎐O), 142.9–127.1 (Ph), 111.4 (d,
(d, J = 10 Hz, CpЈ), 79.9 (CpЈ), 72.1 (d, J = 7 Hz, CpЈ), 58.8 (d,
J = 4 Hz, CH2O), 26.5 (d, J = 34 Hz, CH2P), 16.3 (CpЈCH3),
13.7 (CpЈCH3). 31P NMR (160 MHz): δ 127.6 (d, J = 71 Hz),
31.2 (d, J = 71 Hz). Minor product (2g-I): 1H NMR (400 MHz):
δ 7.81 (br, 2H, Ph), 7.52–6.83 (m, 23H, Ph), 5.15–5.08 (m, 1H,
OCH2), 4.52 (s, 1H, CpЈ), 4.06–4.01 (m, 1H, OCH2), 3.68–3.65
(m, 1H, CH2P), 3.25 (s, 1H, CpЈ), 2.64–2.54 (m, 1H, CH2P),
2.41 (s, 3H, CpЈCH3), 2.16 (s, 3H, CpЈCH3). 31P NMR (160
MHz): δ 132.5 (d, J = 69 Hz), 36.6 (d, J = 69 Hz).
᎐
᎐
J = 4 Hz, CpЈ), 110.8 (CpЈ), 103.2 (CpЈ), 89.8 (d, J = 10 Hz,
CpЈ), 89.4 (CpЈ), 83.5 (d, J = 12 Hz, CpЈ), 83.2 (CpЈ), 78.9 (d, J =
7 Hz, CpЈ), 75.8 (CpЈ), 58.9–58.6 (OCH2), 28.4 (d, J = 34 Hz,
PCH2), 20.8 (d, J = 26 Hz, PCH2), 17.6 (CЈpCH3), 15.6
(CpЈCH3), 11.9 (CpЈCH3), 11.6 (CpЈCH3). Major product (2d-I):
1H NMR (400 MHz): δ 7.91 (br, 2H, Ph), 7.64–6.79 (m, 23H,
Ph), 4.99–4.92 (m, 1H, OCH2), 4.64 (s, 1H, CpЈ), 3.98 (s, 1H,
CpЈ), 3.74–3.71 (m, 1H, OCH2), 2.78–2.66 (m, 1H, CH2P),
2.67 (s, 3H, CpЈCH3), 2.14–2.08 (m, 1H, CH2P), 1.24 (s, 3H,
CpЈCH3). 31P NMR (160 MHz): δ 38.0 (d, J = 35 Hz), 23.5
(ꢀ5:ꢀ1-2-Me-4-Ph-C5H2CO2CH2CH2PPh2)Ru[P(OPh)3]I (2h-
I and 2h-II). IR [KBr, νmax/cmϪ1]: 1717 (C᎐O) cmϪ1. FAB MS:
᎐
m/z 950 (Mϩ). Calc. for C45H39IO5P2Ru: C, 56.91; H, 4.14; I,
13.36%. Found: C, 57.11; H, 3.92; I, 13.11%. Major product: 1H
NMR (400 MHz): δ 7.84–7.76 (m, 2H, Ph), 7.55–6.89 (m, 22H,
Ph), 6.54 (d, 6H, J = 8.1 Hz, Ph), 5.51 (s, 1H, CpЈ), 5.25–5.04
(m, 1H, OCH2), 4.44 (s, 1H, CpЈ), 4.20–4.13 (m, 1H, OCH2),
3.83–3.74 (m, 1H, CH2P), 2.71–2.57 (m, 1H, CH2P), 2.64 (s, 3H,
1
(d, J =35 Hz). Minor product (2d-II): H NMR (400 MHz):
δ 7.64–6.79 (m, 23H, Ph), 6.43 (t, 2H, J = 7.8 Hz, Ph), 4.99–4.92
(m, 1H, OCH2), 4.97 (s, 1H, CpЈ), 3.92 (s, 1H, CpЈ), 3.88 (m,
1H, OCH2), 3.74–3.71 (m, 1H, CH2P), 2.73 (s, 3H, CpЈCH3),
2.44 (m, 1H, CH2P), 1.19 (s, 3H, CpЈCH3). 31P NMR (160
MHz): δ 40.3 (d, J = 36 Hz), 30.3 (d, J = 36 Hz).
CpЈCH3). 13C NMR (150 MHz): δ 167.0 (C᎐O), 152.1–121.3
᎐
(Ph), 117.7 (Cp), 95.4 (CpЈ), 81.9 (CpЈ), 79.7 (CpЈ), 78.4 (d,
J = 9 Hz, CpЈ), 59.0 (d, J = 4 Hz, CH2O), 24.6 (d, J = 34 Hz,
CH2P), 13.2 (CpЈCH3). 31P NMR (160 MHz): δ 126.1 (d,
(ꢀ5:ꢀ1-2-Me-4-Ph-C5H2CO2CH2CH2PPh2)Ru(PPh3)I (2e-I
and 2e-II). IR [KBr, νmax/cmϪ1]: 1715 (C᎐O). FAB MS: m/z 902
᎐
D a l t o n T r a n s . , 2 0 0 4 , 5 4 7 – 5 5 3
551

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1
J = 69 Hz), 35.4 (d, J = 69 Hz). Minor product: H NMR (400
MHz): δ 7.84–7.76 (m, 2H, Ph), 7.55–6.89 (m, 28H, Ph), 5.25–
5.04 (m, 1H, OCH2), 5.16 (s, 1H, CpЈ), 4.27 (s, 1H, CpЈ), 3.83–
3.74 (m, 1H, OCH2), 3.41–3.32 (m, 1H, CH2P), 2.71–2.57 (m,
1H, CH2P), 2.40 (br, 3H, CpЈCH3). 31P NMR (160 MHz):
δ 127.8 (d, J = 69 Hz), 32.8 (d, J = 69 Hz).
(ꢀ5:ꢀ1-2-Me-4-But-C5H2CO2CH2CH2PPh2)Ru[P(OPh)3]I (2i-
II). 1H NMR (400 MHz): δ 8.06–8.01 (m, 2H, Ph), 7.66 (t, 2H,
J = 8.4 Hz, Ph), 7.47–7.40 (m, 3H, Ph), 7.26–7.17 (m, 3H, Ph),
7.08 (t, 6H, J = 7.8 Hz, Ph), 6.96 (t, 3H, J = 7.3 Hz, Ph), 6.89 (d,
6H, J = 7.8 Hz, Ph), 5.14 (dd, 1H, J = 5.6, 2.0 Hz, CpЈ), 5.04–
4.94 (m, 1H, OCH2), 3.74 (t, 1H, J = 2.0 Hz, CpЈ), 3.62–3.60 (m,
1H, OCH2), 3.31–3.22 (m, 1H, CH2P), 2.48 (dt, 1H, J = 14.2,
4.2 Hz, CH2P), 2.40 (d, 3H, J = 4.4 Hz, CpЈCH3), 1.35 (s, 9H,
But). 13C NMR (150 MHz): δ 168.5 (C᎐O), 152.3–121.6 (Ph),
᎐
101.1 (CpЈ), 80.0 (CpЈ), 77.4 (d, J = 3.7 Hz, CpЈ), 75.6 (d, J = 15
Hz, CpЈ), 74.4 (d, J = 11 Hz, CpЈ), 59.4 (d, J = 4 Hz, CH2O),
33.8 (CMe3), 30.5 (CMe3), 22.2 (d, J = 30 Hz, CH2P), 13.2
(CpЈCH3). 31P NMR (160 MHz): δ 128.5 (d, J = 70 Hz), 28.6 (d,
J = 70 Hz). IR [KBr, νmax/cmϪ1]: 1725 (C᎐O). FAB MS: m/z 930
᎐
(Mϩ). Calc. for C43H43IO5P2Ru: C, 55.55; H, 4.66; I, 13.65%.
Found: C, 55.30; H, 4.50; I, 13.80%.
X-ray diffraction analyses of complexes 2a-I, 2b-I, 2d-I, 2e-I,
2f-II, 2g-II, and 2i-II. Crystals suitable for X-ray diffraction
were obtained by recrystallization from the dichloromethane–
hexane solution for 2a-I and 2b-I and from the dichloro-
methane–methanol solution of the diastereomixture for 2e-I,
2f-II, 2g-II, and 2i-II. The crystals were mounted on a glass
fiber with epoxy resin. All measurements were performed on
Rigaku AFC5R or AFC7R automated four-circles diffract-
ometer using graphite monochromated Mo–Kα radiation
(λ = 0.71069 Å) at Ϫ50 or Ϫ70 ЊC in the range of 6Њ < 2θ < 55Њ
with a scan rate of 16Њ minϪ1. Three standard reflections were
monitored at every 150 measurements. Although no damage
was observed for complexes 2a-I, 2d-I, 2e-I, 2f-II, and 2g-II, the
standards decreased during the measurements for complexes
2b-I and 2i-II. Thus, a linear correction was made for the data
of these complexes. Intensities were corrected for Lorentz and
polarization effects, and for absorption using ψ-scan technique.
The structures were solved by Patterson methods and refined by
full-matrix least-squares minimizing of Σω(|Fo| Ϫ |Fc|)2. Aniso-
tropic thermal parameters were used for all non-hydrogen
atoms and hydrogen atoms were located at calculated positions.
The final cycles of full matrix least squares refinement were
converged. Crystallographic data are summarized in Table 3.
CCDC reference numbers 200477–200483.
See http://www.rsc.org/suppdata/dt/b3/b314859a/ for crystal-
lographic data in CIF or other electronic format.
Acknowledgements
This work was supported by a Grant-in-Aid for Scientific
Research on Priority Areas from the Ministry of Education,
Science, Sports and Culture, and by the Tokuyama Science
Foundation (K. O.). The author (Y. M.) gratefully acknow-
ledges a JSPS Fellowship for Japan Junior Scientists. We thank
The Material Analysis Center, ISIR, Osaka University, for their
support with the spectral measurements, X-ray diffraction
studies and elemental analyses.
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