Synthesis, structure, and reactivity of novel ruthenium(II) phenolate complexes

Article abstract of DOI:10.1021/om0491600

Reaction of Ru(η⁶-cot)(dmfm)₂ (1) [cot = 1,3,5-cyclooctatriene, dmfin = dimethyl fumarate] with phenol was investigated. At 110°C, a novel ruthenium(II) phenolate complex, Ru(η⁵- C₆H₅O)(η⁵-C₈H₁₁) (2), was obtained by the reaction of 1 with phenol in an isolated yield of 52% (74% by NMR). When the reaction was carried out at 130°C, further dehydrogenative ring-closure in an η⁵-cyclooctadienyl ligand occurred to give Ru(η⁵-C₆H₅O)(η⁵-C ₈H₉) (3) in an isolated yield of 61% (76% by NMR). For both complexes, the η⁵-oxocyclohexadienyl bonding mode of a phenoxo ligand was clearly shown by X-ray crystallography and DFT calculation. Complex 2 was smoothly transformed into complex 3 in the presence of dmfm at 130°C for 3 h. Selective O-methylation of an η⁵- oxocyclohexadienyl ligand in complex 3 proceeded with methyl p-toluenesulfonate to give a novel cationic ruthenium(II) complex, [Ru(η⁶-C ₆H₅OMe)(η⁵-C₈H ₉)]⁺OTs^- (4), in an isolated yield of 74%.

Full text of DOI:10.1021/om0491600

Organometallics 2005, 24, 905-910
905
Synthesis, Structure, and Reactivity of Novel
Ruthenium(II) Phenolate Complexes
Teruyuki Kondo, Fumiaki Tsunawaki, Yasuyuki Ura, Kazuo Sadaoka,
Tomomichi Iwasa, Kenji Wada, and Take-aki Mitsudo*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering,
Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
Received October 29, 2004
Reaction of Ru(η6-cot)(dmfm)2 (1) [cot ) 1,3,5-cyclooctatriene, dmfm ) dimethyl fumarate]
with phenol was investigated. At 110 °C, a novel ruthenium(II) phenolate complex, Ru(η5-
C6H5O)(η5-C8H11) (2), was obtained by the reaction of 1 with phenol in an isolated yield of
52% (74% by NMR). When the reaction was carried out at 130 °C, further dehydrogenative
ring-closure in an η5-cyclooctadienyl ligand occurred to give Ru(η5-C6H5O)(η5-C8H9) (3) in
an isolated yield of 61% (76% by NMR). For both complexes, the η5-oxocyclohexadienyl
bonding mode of a phenoxo ligand was clearly shown by X-ray crystallography and DFT
calculation. Complex 2 was smoothly transformed into complex 3 in the presence of dmfm
at 130 °C for 3 h. Selective O-methylation of an η5-oxocyclohexadienyl ligand in complex 3
proceeded with methyl p-toluenesulfonate to give a novel cationic ruthenium(II) complex,
[Ru(η6-C6H5OMe)(η5-C8H9)]+OTs- (4), in an isolated yield of 74%.
Introduction
On the other hand, in a continuation of our study of
Ru(η6-cot)(dmfm)2 (1)5 [cot ) 1,3,5-cyclooctatriene, dmfm
) dimethyl fumarate], we recently showed that a variety
of novel zerovalent ruthenium complexes such as mono-
and diphosphine,6 aqua,7 p-quinone,8 amine,9a poly-
(pyridyl),9b,c and η6-arene complexes10 were prepared in
high yields with high selectivity using complex 1 as a
versatile starting material.
Phenols form an interesting class of arenes and are
attractive in coordination chemistry.1 The most obvious
potential anionic π-arene ligand is the phenoxide ion,
C6H5O-. Whether this ion will bind to the metal through
oxygen as in well-known phenoxo complexes2 or will be
π-bonded as in oxocyclohexadienyl complexes3 depends
on the nature of the metal and its ligands. As for the
ruthenium, in a pioneering study by Wilkinson and co-
workers, the first ruthenium(II) phenolate complex,
RuH(C6H5O)(PPh3)2, was synthesized, and its structure
was discussed by the spectroscopic analyses in 1976.4
Herein, we report the synthesis of novel ruthenium-
(II) phenolate complexes, in which a phenoxide ligand
has an η5-oxocyclohexadienyl mode, by the reaction of
complex 1 with phenol. In the present reaction, forced
deprotonation of phenol was not needed, and a cot ligand
smoothly inserted into a hydrido-ruthenium bond,
which was generated by oxidative addition of phenol to
1, to give an η5-cyclooctadienyl ligand. The structures
of new ruthenium(II) phenolate complexes are con-
firmed by IR, NMR, and X-ray analyses as well as DFT
calculation.
* To whom correspondence should be addressed. E-mail: mitsudo@
scl.kyoto-u.ac.jp.
(1) (a) Chisholm, M. H.; Rothwell, I. P. In Comprehensive Coordina-
tion Chemistry; Wilkinson, G., Gillard, T. D., McCleverty, J. A., Eds.;
Pergamon: Oxford, 1987; Vol. 2, pp 336-364. (b) Mehrotra, R. C.;
Agarwal, S. K.; Singh, Y. P. Coord. Chem. Rev. 1985, 68, 101. (c)
Bryndza, H. E.; Tam, W. Chem. Rev. 1988, 88, 1163.
(2) For recent examples for Rh and Ir, see: (a) Green, L. M.; Meek,
D. W. Organometallics 1989, 8, 659. For Ni and Pd, see: (b) Kim, Y.-
J.; Osakada, K.; Takenaka, A.; Yamamoto, A. J. Am. Chem. Soc. 1990,
112, 1096. (c) Klein, H.-F.; Dal, A.; Jung, T.; Braun, S.; Ro¨hr, C.; Flo¨rke,
U.; Haupt, H.-J. Eur. J. Inorg. Chem. 1998, 621. (d) Ca´mpora, J.; Reyes,
M. L.; Mereiter, K. Organometallics 2002, 21, 1014. (e) Mann, G.;
Shelby, Q.; Roy, A. H.; Hartwig, J. F. Organometallics 2003, 22, 2775.
For Pt, see: (f) Dockter, D. W.; Fanwick, P. E.; Kubiak, C. P. J. Am.
Chem. Soc. 1996, 118, 4846. For bridging or chelate-assisted Ru
phenolates, see: (g) Bu¨cken, K.; Koelle, U.; Pasch, R.; Ganter, B.
Organometallics 1996, 15, 3095. (h) Sinha, P. K.; Falvello, L. R.; Peng,
A.-M.; Bhattacharya, S. Polyhedron 2000, 19, 1673, and references
therein.
(3) (a) Ca´mpora, J.; Reyes, M. L.; Hackl, T.; Monge, A.; Ruiz, C.
Organometallics 2000, 19, 2950, and references therein. For Mn, see:
(b) Lee, S.-G.; Kim, J.-A.; Chung, Y. K.; Yoon, T.-S.; Kim, N.; Shin,
W.; Kim, J.; Kim, K. Organometallics 1995, 14, 1023. For Rh and Ir,
see: (c) White, C.; Thompson, S. J.; Maitlis, P. M. J. Organomet. Chem.
1977, 127, 415. (d) Bras, J. L.; Amouri, H. E.; Besace, Y.; Vaissermann,
J.; Jaouen, G. Bull. Soc. Chim. Fr. 1995, 132, 1073. (e) Bras, J. L.;
Amouri, H. E.; Vaissermann, J. Organometallics 1996, 15, 5706. (f)
Bras, J. L.; Amouri, H.; Vaissermann, J. Inorg. Chem. 1998, 37, 5056.
For Ru, see: (g) Koelle, U.; Wang, M. H.; Raabe, G. Organometallics
1991, 10, 2573. (h) Christ, M. L.; Sabo-Etienne, S.; Chung, G.;
Chaudret, B. Inorg. Chem. 1994, 33, 5316. (i) Snelgrove, J. L.; Conrad,
J. C.; Yap, G. P. A.; Fogg, D. E. Inorg. Chim. Acta 2003, 345, 268.
Results and Discussion
Reaction of Ru(η6-cot)(dmfm)2 (1) (0.50 mmol) and an
excess amount of phenol (3.0 g) was carried out at 110
(4) Cole-Hamilton, D. J.; Young, R. J.; Wilkinson, G. J. Chem. Soc.,
Dalton Trans. 1976, 1995.
(5) Mitsudo, T.; Suzuki, T.; Zhang, S.-W.; Imai, D.; Fujita, K.;
Manabe, T.; Shiotsuki, M.; Watanabe, Y.; Wada, K.; Kondo, T. J. Am.
Chem. Soc. 1999, 121, 1839.
(6) Shiotsuki, M.; Suzuki, T.; Kondo, T.; Wada, K.; Mitsudo, T.
Organometallics 2000, 19, 5733.
(7) Shiotsuki, M.; Miyai, H.; Ura, Y.; Suzuki, T.; Kondo, T.; Mitsudo,
T. Organometallics 2002, 21, 4960.
(8) Ura, Y.; Sato, Y.; Shiotsuki, M.; Suzuki, T.; Wada, K.; Kondo,
T.; Mitsudo, T. Organometallics 2003, 22, 77.
(9) (a) Suzuki, T.; Shiotsuki, M.; Wada, K.; Kondo, T.; Mitsudo, T.
J. Chem. Soc., Dalton Trans. 1999, 4231. (b) Suzuki, T.; Shiotsuki,
M.; Wada, K.; Kondo, T.; Mitsudo, T. Organometallics 1999, 18, 3671.
(c) Shiotsuki, M.; Suzuki, T.; Iida, K.; Ura, Y.; Wada, K.; Kondo, T.;
Mitsudo, T. Organometallics 2003, 22, 1332.
(10) Ura, Y.; Shiotsuki, M.; Sadaoka, K.; Suzuki, T.; Kondo, T.;
Mitsudo, T. Organometallics 2003, 22, 1863.
10.1021/om0491600 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 02/02/2005

906 Organometallics, Vol. 24, No. 5, 2005
Kondo et al.
Scheme 1. Synthesis of Novel Ru(II) Phenolate
Complexes
Figure 2. Molecular structure of 3‚2PhOH with thermal
ellipsoids drawn at the 50% probability level. PhOH
molecule and hydrogen atoms are omitted for clarity.
°C for 3 h under an argon atmosphere. After removal
of unreacted phenol at 100 °C under vacuum, the yellow
residue was washed with pentane and diethyl ether and
vacuum-dried to give pale yellow crystals of a novel
ruthenium(II) phenolate complex, Ru(η5-C6H5O)(η5-
C8H11)‚C6H5OH (2‚C6H5OH) [C8H11 ) cyclooctadienyl],
in an isolated yield of 52% (74% by NMR) (Scheme 1,
path A). When the same reaction was carried out at
elevated temperature (at 130 °C), dehydrogenative
ring-closure of an η5-cyclooctadienyl ligand to an η5-
pentalenyl ligand occurred to give Ru(η5-C6H5O)(η5-
C8H9)‚2C6H5OH (3‚2C6H5OH) [C8H9 ) pentalenyl], in
an isolated yield of 61% (76% by NMR) (Scheme 1, path
B). The reaction using phenol as a solvent and a reagent
gave the best result. Concomitant use of other solvents
such as toluene, THF, and 1,2-dichloroethane with
phenol completely suppressed the reaction, and complex
1 was almost recovered without the formation of 2 and
3. In addition, a zerovalent ruthenium complex, Ru(η4-
cod)(η6-cot) [cod ) 1,5-cyclooctadiene], which is the
starting material for the synthesis of complex 1, also
gave 2 and 3 by the reaction of phenol under the same
reaction conditions; however, the yields of 2 and 3 were
quite low (ca. 10% each).
Table 1. Crystallographic Data for the
Structurally Analyzed Complexes 2‚PhOH,
3‚2PhOH, and 4
2‚PhOH
3‚2PhOH
4
empirical
formula
fw
cryst color
habit
cryst size
(mm)
cryst syst
space group
a (Å)
b (Å)
c (Å)
C
20H22O2Ru
C26H26O3Ru C22H24O4RuS
395.46
colorless
needle
0.30 × 0.05
487.56
yellow
block
485.56
colorless
needle
0.30 × 0.30
× 0.10
monoclinic
P21/n (#14)
7.1423(3)
15.720(1)
19.050(1)
90
0.30 × 0.10
× 0.03
× 0.05
monoclinic
P21/c (#14)
6.5555(3)
14.5649(6)
14.6469(6)
90
97.350(1)
90
1387.0(1)
4
monoclinic
P21/n (#14)
6.8703(3)
15.587(1)
18.2670(9)
90
R (deg)
â (deg)
γ (deg)
V (Å3)
94.864(2)
90
93.9791(9)
90
2131.2(2)
4
1951.4(2)
4
Z
Dcalcd (g cm-3
µ(Mo KR)
)
1.894
11.39
1.519
1.653
7.61
9.369
(cm-1
)
λ (Å)
T (°C)
0.71070
-100
0.71070
-100
0.71070
-130
Single crystals of complexes 2 and 3 suitable for X-ray
crystallographic analysis were obtained by slow diffu-
sion of pentane into CH2Cl2 and/or CHCl3 solutions of
2 and 3, respectively. Low-temperature X-ray diffraction
studies of 2 and 3 clearly showed the η5-oxocyclohexa-
dienyl bonding mode of a phenoxo ligand (Figures 1 and
2). The crystal data and the experimental details for 2
and 3 are summarized in Table 1, and lists of the
scan mode
scan width
(deg)
ω-2θ
ω-2θ
ω-2θ
0.9327-1.0431 1.000-1.000 0.8969-1.0721
scan speed
5.0
5.0
5.0
(deg min-1
2θmax (deg)
no. of measd
reflnsa
)
55.0
12 544
55.0
17 486
54.9
17 005
no. of obsd
2320
3746
2180
reflnsb
Rc (%)
3.4
4.5
0.847
3.1
3.5
1.107
3.5
3.7
1.072
Rwc (%)
GOFd
a Total. b I > 3.00σ(I). c R ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) [∑w(|Fo|
- |Fc|)2/∑wFo
]
2
1/2
.
d Goodness of fit.
selected bond distances and angles for both complexes
are provided in Tables 2 and 3.
The average bond distances between Ru and the
five olefinic carbons of a phenoxo ligand (Ru-C2,
Ru-C3, Ru-C4, Ru-C5, and Ru-C6) in 2 and 3 are
2.23 and 2.21 Å, respectively. On the other hand, the
bond lengths between Ru and the carbon bearing the
oxygen atom, i.e., Ru-C1 (2.471(4) and 2.414(2) Å), are
longer than the average distance by ca. 0.2 Å. In
addition, the bond distances of C1-O1 in complexes 2
and 3 are 1.256(5) and 1.283(3) Å, respectively, which
Figure 1. Molecular structure of 2‚PhOH with thermal
ellipsoids drawn at the 50% probability level. PhOH
molecule and hydrogen atoms are omitted for clarity.

Ruthenium(II) Phenolate Complexes
Organometallics, Vol. 24, No. 5, 2005 907
Table 2. Selected Bond Distances (Å) and Angles
(deg) of Complexes 2 and 3
Scheme 2. Resonance Hybrids for π-Complexing
of Phenoxo Group
2‚PhOH
3‚2PhOH
Bond Distances
2.471(4)
2.216(4)
2.209(5)
2.255(5)
2.219(4)
2.248(4)
2.184(4)
2.145(4)
2.193(4)
2.150(5)
2.168(4)
3.277(5)
3.695(5)
3.310(5)
1.256(5)
Ru-C1
Ru-C2
Ru-C3
Ru-C4
Ru-C5
Ru-C6
Ru-C7
Ru-C8
Ru-C9
Ru-C10
Ru-C11
Ru-C12
Ru-C13
Ru-C14
C1-O1
2.414(2)
2.237(3)
2.204(3)
2.198(3)
2.193(2)
2.240(2)
2.184(2)
2.196(2)
2.182(3)
2.193(2)
2.179(2)
3.272(3)
3.605(4)
3.272(3)
1.283(3)
Scheme 3. Ring-Closing Transformation of 2 to 3
in the Presence of Dimethyl Fumarate and Phenol
Bond Angles
137.8(3)
Ru-C1-O1
O1-C1-C2
O1-C1-C6
135.7(2)
122.7(2)
122.2(2)
124.1(4)
122.0(4)
indicates that the C-O bond of the phenoxo moiety has
substantial double-bond character, and this is again best
explained in terms of a large contribution from the
η5-oxocyclohexadienyl bonding mode in Scheme 2. In
addition, 13C NMR spectra of 2 and 3 showed the
carbonyl carbons of an η5-oxocyclohexadienyl ligand at
156.78 and 150.16 ppm, respectively.
Complexes 2 and 3 crystallized with additional mol-
ecules of phenol. The obvious and strong hydrogen
bonding between the O-H hydrogen in phenol molecules
and the oxygen of the η5-oxocyclohexadienyl ligands
plays an important part in stabilization of complexes 2
and 3 as well as controlling the reactivity of the
η5-oxocyclohexadienyl ligands in 2 and 3.
Table 3. Selected Bond Distances (Å) and Angles
(deg) of Complex 4
Bond Distances
Ru-C1
Ru-C2
Ru-C3
Ru-C4
Ru-C5
Ru-C6
Ru-C8
Ru-C9
2.233(4)
2.226(4)
2.214(5)
2.204(5)
2.194(5)
2.216(4)
2.190(4)
2.175(4)
Ru-C10
Ru-C11
Ru-C12
Ru-C13
Ru-C14
Ru-C15
C1-O1
2.167(5)
2.188(5)
2.202(4)
3.301(4)
3.591(4)
3.282(5)
1.357(6)
1.425(7)
O1 -C7
Bond Angles
Ru-C1-O1
C1-O1-C7
131.1(3)
117.8(4)
O1-C1-C2
O1-C1-C6
115.6(4)
123.6(4)
Since complex 3 was considered to be generated
from 1 via 2, transformation of complex 2 to 3 was
investigated. Actually, when complex 2 was treated
with phenol in the presence of dmfm at 130 °C for
3 h, complex 3 was obtained in an NMR yield of 84%
(Scheme 3).
Without dmfm, the yield of 3 was drastically de-
creased. From careful analysis of the reaction mixture
obtained from Scheme 3, dimethyl succinate, which
would be formed by hydrogenation of dmfm, was de-
tected by the 1H NMR spectrum. Synthesis of a pental-
enyl ruthenium complex by gas phase reaction of
cyclooctadienyl ruthenium complex11 or by the reaction
of cyclododeca-1,5,9-triene12 and cyclooctatetraene13
with bis(germyl)ruthenium and osmium complexes has
already been reported. However, the reaction conditions
are sometimes severe and the yields of the product
complexes were not satisfactory. Moreover, the mech-
anism of the ring contraction of cyclododeca-1,5,9-triene
is not yet clear.
are a typical length in transition metal quinone com-
plexes.
Simplified side views of complexes 2 and 3 are shown
in Figure 3. The dihedral angles between the plane of
five olefinic carbons, C2-C6, and the planes that include
C1, C2, and C6 are 17.8° and 11.1°, respectively.
However, these values are small compared to those in
other η5-oxocyclohexadienyl complexes. Thus, we ex-
pect that there should be a small contribution of the
η6-phenoxide bonding mode in the structure (Scheme
2). The hydrogen atoms in the η5-oxocyclohexadienyl
ligands of 2 and 3 are located at slightly leaned positions
toward the ruthenium center, and the η5-oxocyclohexa-
dienyl ligands are shaped like an umbrella, which are
consistent with the DFT optimized structures.
Further information of the phenoxo ligand arises from
the position of ν(C-O) in the complexes. In the IR
spectra, both 2 and 3 showed strong ν(C-O) absorption
bands at 1536 and 1529 cm-1, respectively. In compari-
son, ν(C-O) for complexes of O-bonded phenoxide
usually occur in the region of 1200-1300 cm-1. This
The structures and the electronic characters of the
complexes were optimized by DFT calculation at the
(11) Kirss, R. U.; Quazi, A.; Lake, C. H.; Churchill, M. R. Organo-
metallics 1993, 12, 4145.
(12) (a) Knox, S. A. R.; Phillips, R. P.; Stone, F. G. A. J. Chem. Soc.,
Chem. Commun. 1972, 1227. (b) Knox, S. A. R.; Phillips, R. P.; Stone,
F. G. A. J. Chem. Soc., Dalton Trans. 1974, 658.
(13) (a) Harris, P. J.; Howard, J. A. K.; Knox, S. A. R.; Phillips, R.
P.; Stone, F. G. A.; Woodward, P. J. Chem. Soc., Dalton Trans. 1976,
377. (b) Harris, P. J.; Howard, J. A. K.; Knox, S. A. R.; McKinney, R.
J.; Phillips, R. P.; Stone, F. G. A.; Woodward, P. J. Chem. Soc., Dalton
Trans. 1978, 403. (c) Humphries, A. P.; Knox, S. A. R. J. Chem. Soc.,
Dalton Trans. 1978, 1523.
Figure 3. Simplified side views of 2 and 3. Hydrogen
atoms and η5-cyclooctadienyl and η5-pentalenyl ligands are
omitted for clarity.

908 Organometallics, Vol. 24, No. 5, 2005
Kondo et al.
Figure 4. Drawings of HOMO of (a) 2 and (b) 3, and those
of HOMO-1 of (c) 2 and (d) 3 estimated by DFT calculation
at the B3LYP/SDD + 6-31G(d,p) level.
Figure 5. Molecular structure of 4 with thermal ellipsoids
drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
Scheme 4. Synthesis of 4 by O-Methylation of 3
with Methyl p-Toluenesulfonate
Scheme 5. Plausible Mechanism for the
Formation of 2 and 3 from 1
B3LYP/SDD + 6-31G(d,p) level. The intramolecular
dimensions of the theoretically optimized structures of
2 and 3 are generally comparable to those found in the
solid state structure. For example, the bond distances
between Ru1 and C2-C6 (average) and C1-O1 are 2.28
and 1.23 Å for 2 and 2.24 and 1.23 Å for 3, respectively,
very close to the values found in the solid state struc-
tures. The dihedral angles between the plane of
C2-C6 and that of C1, C2, and C6 are 19.8° for 2 and
20.7° for 3. This indicates that the DFT study slightly
underestimates the contribution of the η6-phenoxide
bonding mode.
The shapes of the HOMOs and sub-HOMOs of 2 and
3 indicate the presence of antibonding repulsions, which
would destabilize the π component of the C1-O1 bonds
to some extent, as shown in Figure 4. Such destabiliza-
tion would increase the nucleophilic character of O1
atoms. The DFT calculation also revealed that the trans-
formation of the complex 2 to 3 is thermodynamically
favored by 34.1 kcal mol-1 based on electronic and zero-
point energies when the two hydrogen atoms are re-
moved by hydrogenation of dmfm to dimethyl succinate.
Further reactivity of complex 3 was shown by the
reaction with methyl p-toluenesulfonate. The oxygen
atom of the η5-oxocyclohexadienyl ligand is still nucleo-
philic (vide supra), and selective O-methylation of
this ligand gave a novel cationic ruthenium(II) complex,
[Ru(η6-C6H5OMe)(η5-C8H9)]+OTs- (4), in an isolated
yield of 74%. Single crystals of complex 4 suitable for
X-ray crystallographic analysis were also obtained by
slow diffusion of pentane into CHCl3 solutions of 4
(Scheme 4 and Figure 5). As can be readily seen from
Figure 5, η6-coordination of the C6H5OMe ligand is
apparent and the six carbons (C1-C6) of the C6H5
moiety are almost in one plane. The bond length of
C1-Ru1 (2.233(4) Å) was shorter than those in 2
(2.471(4) Å) and 3 (2.414(2) Å), while the bond length
of C1-O1 (1.357(6) Å) was longer than those in 2
(1.256(5) Å) and 3 (1.283(3) Å) (see Tables 2 and 3). In
addition, no phenol molecule was observed in the crystal
structure of 4.
Considering the results described above, the most
plausible pathway for the formation of 2 and 3 from 1
is illustrated in Scheme 5. We now believe that the
initial step of the present reaction is oxidative addition
of phenol to 1, which gives a (hydrido)(phenoxo)ruthe-
nium complex with liberation of one dmfm ligand.
Insertion of a 1,3,5-cyclooctatriene ligand into a hy-
drido-ruthenium bond and the subsequent σ-π rear-
rangement of the phenoxo ligand with dissociation of
another dmfm ligand would give the novel ruthenium-
(II) phenolate complex 2 in high yield with high selec-
tivity. Hence, at 130 °C, further dehydrogenative ring-
closure of an η5-cyclooctadienyl ligand in 2 occurs to give
pentalenyl complex 3.
Conclusion
In conclusion, novel ruthenium(II) phenolate com-
plexes, 2 and 3, were synthesized by simple and selec-

Ruthenium(II) Phenolate Complexes
Organometallics, Vol. 24, No. 5, 2005 909
vacuum at 100 °C led to a pale yellow solid of complex
3‚2C6H5OH, which was washed with pentane and diethyl ether
(ca. 5 mL each) and vacuum-dried (150 mg, 61% yield).
Crystals suitable for X-ray analysis were grown by layering
pentane on a concentrated CHCl3 solution at room tempera-
ture. Mp: 96.1-96.8 °C (dec). IR (KBr disk): 1604, 1590, 1522,
tive oxidative transformation of 1 with phenol. The
phenoxo ligand can be considered to be bound as an η6-
phenoxo or more realistically as an η5-oxocyclohexadi-
enyl ligand, even though the oxygen atom showed high
nucleophilicity. Our current interest is now focusing on
the application of these complexes to new catalytic
reactions such as anti-Markovnikov addition of phenol
and/or alcohols to terminal alkenes.
1
1464 cm-1. H NMR (CDCl3, 400 MHz): δ 2.25-2.40 (m, 6H,
CH2 of C8H9), 4.74 (t, 1H, CH of C8H9, J ) 2.0 Hz), 4.79 (d,
2H, CH of C8H9, J ) 2.0 Hz), 5.21 (t, 1H, CH of C6H5O, J )
5.4 Hz), 5.29 (d, 2H, CH of C6H5O, J ) 6.8 Hz), 5.43 (dd, 2H,
CH of C6H5O, J ) 1.5, 5.4 Hz). 13C NMR (CDCl3, 100 MHz):
δ 25.36 (2C), 29.05, 70.00 (2C), 76.59 (2C), 76.59, 78.15 (2C),
84.52, 106.61, 150.16. HR-MS(FAB-m-NBA): m/z calcd for
C14H15ORu 301.0170 (M+ + H), found 301.0165 (M+ + H).
Anal. Calcd for C14H14ORu‚1.5C6H5OH: C, 62.71; H, 5.26.
Found: C, 63.06; H, 5.29.
Experimental Section
General Methods. All experiments and manipulations
were carried out under an atmosphere of argon. Reactions were
performed using standard Schlenk techniques and in dried and
thoroughly deoxygenated solvents. Unless otherwise stated,
all reagents were used as received from commercial suppliers.
Synthesis of [Ru(η6-C6H5OMe)(η5-C8H9)]+OTs- (4). A
mixture of Ru(η5-C6H5O)(η5-C8H9)‚2C6H5OH (3‚2PhOH) (61.9
mg, 0.13 mmol), methyl p-toluenesulfonate (0.20 mL, 1.33
mmol), and THF (2.5 mL) was placed in a two-necked 20 mL
Schlenk flask equipped with a magnetic stirring bar under a
flow of argon. The mixture was stirred at room temperature
for 12 h. The resulting solution was then concentrated to give
the white residue of complex 4, which was washed with
pentane and diethyl ether (ca. 5 mL each) and vacuum-dried
(46.4 mg, 74% yield). Crystals suitable for X-ray analysis were
grown by layering pentane on a concentrated CHCl3 solution
at room temperature. Mp: 142.1-144.5 °C (dec). IR (KBr
disk): 1700, 1683, 1664 cm-1. 1H NMR (CD2Cl2, 400 MHz): δ
2.35 (s, 3H, Me of OTs-), 2.37-2.44 (m, 6H, CH2 of pentalenyl),
3.81 (s, 3H, OMe), 5.22 (dd, 1H, CH of pentalenyl, J ) 1.0,2.0
Hz), 5.23 (d, 2H, CH of pentalenyl, J ) 2.0 Hz), 5.86 (t, 1H,
CH of PhOMe, J ) 5.9 Hz), 6.09 (t, 2H, CH of PhOMe, J ) 5.9
Hz), 6.21 (d, 2H, CH of PhOMe, J ) 6.8 Hz), 7.16 (d, 2H, CH
of OTs-, J ) 8.8 Hz), 7.70 (d, 2H, CH of OTs-, J ) 7.8 Hz).
13C NMR (CD2Cl2, 100 MHz): δ 21.38, 25.62 (2C), 29,42 (2C),
57.76, 73.67 (2C), 75.51 (2C), 82.45, 83.73, 85.30 (2C), 110.33,
125.15 (2C), 128.72, 134.43, 139.31. HR-MS(FAB-m-NBA): m/z
calcd for C15H17ORu 315.0327, found 315.0338 (M+).
Dehydrogenative Ring-Closing Reaction of 2 to 3. A
mixture of Ru(η5-C6H5O)(η5-C8H11)‚C6H5OH (2‚PhOH) (138 mg,
0.35 mmol), phenol (1.0 g), and dimethyl fumarate (72.2 mg,
0.50 mmol) was placed in a two-necked 20 mL Schlenk flask
equipped with a magnetic stirring bar and a reflux condenser
under a flow of argon. The mixture was heated at 130 °C for
3 h with stirring. Then, the reaction mixture was cooled, and
removal of excess phenol under vacuum at 100 °C led to a pale
yellow solid, which was washed with pentane and diethyl ether
(ca. 5 mL each) and vacuum-dried (3‚2PhOH, 84% yield by
NMR).
Ru(η6-cot)(dmfm)2 and Ru(η4-cod)(η6-cot)14 were prepared as
5
described in the literature. The 1H NMR spectra were recorded
at 400 MHz, while 13C NMR spectra were recorded at 100 MHz
with a JEOL EX400 spectrometer at 25 °C. Samples were
analyzed in CDCl3 or CD2Cl2, and the chemical shifts are given
in ppm relative to Me4Si. Dibenzil was used as an internal
standard in order to determine the NMR yields of 2 and 3. IR
spectra were obtained on a Nicolet Impact 410 spectrometer.
GC/MS analyses were performed using a Shimadzu QP5000
mass spectrometer connected with a Shimadzu GC-17A gas
chromatograph [column: J & W Scientific capillary column
DB-1, 0.25 mm i.d. × 25 m (film thickness 0.25 µm)]. Melting
points were measured on a Yanagimoto micro melting point
apparatus under an atmosphere of argon and are uncorrected.
High-resolution mass spectra (FAB) were recorded on a JEOL
SX102A spectrometer with m-nitrobenzyl alcohol (m-NBA)
as a matrix. Elemental analyses were performed at the
Microanalytical Center of Kyoto University.
Synthesis
of
Ru(η5-C6H5O)(η5-C8H11)‚C6H5OH
(2‚C6H5OH). A mixture of Ru(η6-cot)(dmfm)2 (1) (250 mg, 0.50
mmol) and phenol (3.0 g) was placed in a two-necked 50 mL
Schlenk flask equipped with a magnetic stirring bar and a
reflux condenser under a flow of argon. The mixture was
heated at 110 °C for 3 h with stirring. Then, the reaction mix-
ture was cooled, and removal of excess phenol under vacuum
at 100 °C led to a colorless solid of complex 2‚C6H5OH, which
was washed with pentane and diethyl ether (ca.. 5 mL each)
and vacuum-dried (103 mg, 52%). Crystals suitable for X-ray
analysis were grown by layering pentane on a concentrated
CH2Cl2 solution at room temperature. Mp: 122.8-125.2 °C
(dec). IR (KBr disk): 1575, 1527, 1473 cm-1. 1H NMR (CDCl3,
400 MHz): δ 0.03 (tq, 1H, CHH of C8H11, J ) 2.7, 8.3 Hz),
1.17-1.24 (m, 1H, CHH of C8H11), 1.41 (dt, 1H, CHH of C8H11,
J ) 2.9, 7.3 Hz), 1.46 (dt, 1H, CHH of C8H11, J ) 2.9, 7.3 Hz),
1.85-1.92 (m, 2H, CH2 of C8H11), 3.84 (dt, 2H, CH of C8H11, J
) 3.4, 4.4 Hz), 4.47 (t, 2H, CH of C8H11, J ) 7.3 Hz), 5.24 (t,
1H, CH of C8H11, J ) 5.4 Hz), 5.40 (d, 2H, CH of C6H5O,
J ) 6.3 Hz), 5.54 (dd, 2H, CH of C6H5O, J ) 1.5, 5.4 Hz),
6.11 (t, 1H, CH of C6H5O, J ) 6.3 Hz). 13C{1H} NMR (CDCl3,
100 MHz): δ 19.66, 28.97, 29.06, 55.04 (2C), 79.25 (2C),
81.49, 81.70 (2C), 93.56 (2C), 103.53, 156.78. HRMS(FAB-m-
NBA): m/z calcd for C14H15ORu 301.0170 (M+ + H - 2H),
found 301.0178 (M+ + H - 2H). Anal. Calcd for C14H16ORu‚
0.5C6H5OH: C, 58.61; H, 5.50. Found: C, 59.11; H, 5.42.
Crystallographic Study of Complexes 2, 3, and 4. The
crystal data and experimental details for 2, 3, and 4 are
summarized in Table 1. All measurements were made on a
Rigaku RAXIS imaging plate area detector with graphite-
monochromated Mo KR radiation (λ ) 0.71069 Å). The
structures were solved by direct methods using SIR9215 and
expanded using Fourier techniques, DIRDIF99.16 Hydrogen
atoms were refined using the riding model. Neutral atom-
scattering factors were taken from Cromer and Waber.17
18
Anomalous dispersion effects were included in Fcalc
;
the
values for ∆f ′ and ∆f ′′ were those of Creagh and McAuley.19
Synthesis
of
Ru(η5-C6H5O)(η5-C8H9)‚2C6H5OH
The values for the mass attenuation coefficients were those
(3‚2C6H5OH). A mixture of Ru(η6-cot)(dmfm)2 (1) (250 mg, 0.50
mmol) and phenol (3.0 g) was placed in a two-necked 50 mL
Schlenk flask equipped with a magnetic stirring bar and a
reflux condenser under a flow of argon. The mixture was
heated at 130 °C for 3 h with stirring. Then, the reaction
mixture was cooled, and removal of excess phenol under
(15) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.;
Burla, M.; Polidori, G.; Camalli, M. J. Appl. Crystallogr. 1994, 27, 435.
(16) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
de Gelder, R.; Israel, R.; Smits, J. M. M. The DIRDIF-99 program
system; Technical Report of the Crystallography Laboratory: Univer-
sity of Nijmegen, The Netherlands, 1999.
(17) Cromer, D. T.; Waber, J. T. International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, England, Vol. IV,
1974.
(14) Itoh, K.; Nagashima, H.; Ohshima, T.; Oshima, N.; Nishiyama,
H. J. Organomet. Chem. 1984, 272, 179.
(18) Ibers, J. A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.

910 Organometallics, Vol. 24, No. 5, 2005
Kondo et al.
of Creagh and Hubbell.20 All calculations were performed using
the CrystalStructure21,22 crystallographic software package.
Theoretical Calculations. To consistently compare the
single-point energies of model complexes, calculations were
carried out using density functional theory (DFT) optimized
geometries. Calculations were performed using the Gaussian
03 RevB.0423 implementation of B3LYP [Becke three-param-
eter exchange functional (B3)24 and the Lee-Yang-Parr
correlation functional (LYP)25] on Intel PIV computers at the
Kyoto University. The basis set is the combination of the
Stuttgart-Dresden-Bonn energy-consistent pseudopotential
(SDD)26 for Ru and the 6-31G(d,p) basis set for all other
hydrogen, carbon, and oxygen atoms. No constraints were
imposed for all the systems. Frequency calculations on opti-
mized species established that all the transition states pos-
sessed only one imaginary frequency. Zero-point energy and
thermodynamic functions were computed at standard temper-
ature (298.15 K) and pressure (1 atm). Spatial plots of the
optimized geometries and frontier orbitals were obtained from
Gaussian 03 output using Cambridge Soft Corporation’s Chem
3D Pro v4.0 and Fujitsu WinMOPAC v3.5.
(19) Creagh, D. C.; McAuley, W. J. International Tables for X-ray
Crystallography; Kluwer Academic Publishers: Boston, Vol. C, 1992.
(20) Creagh, D. C.; Hubbell, J. H. International Tables for X-ray
Crystallography; Kluwer Academic Publishers: Boston, Vol. C, 1992.
(21) CrystalStructure 2.00, Crystal Structure Analysis Package;
Rigaku and MSC, 2001.
(22) Watkin, D. J.; Prout, C. K.; Carruthers, J. R.; Betteridge, P.
W. CRYSTALS Issue 10; Chemical Crystallography Laboratory: Ox-
ford, UK.
Acknowledgment. This work was supported in part
by Grants-in-Aid for Scientific Research (A), (B) and
Scientific Research on Priority Areas from the Japan
Society for the Promotion of Science and the Ministry
of Education, Culture, Sports, Science and Technology,
Japan. T.K. acknowledges financial support from the
Sumitomo Foundation.
(23) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo,
C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin,
A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma,
K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.;
Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.;
Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui,
Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.;
Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challa-
combe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. Gaussian 03, revision B.04; Gaussian, Inc.:
Pittsburgh, PA, 2003.
Supporting Information Available: X-ray diffraction
data for complexes 2, 3, and 4 in the form of CIF files. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM0491600
(25) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. 1988, B37, 785.
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