Cyclopenta[J.]phenanthrenyl and Cyclopenta[a]acenaphthylenyl Half-Sandwich Complexes of Ruthenium as Racemization Catalysts for Secondary Alcohols

Article abstract of DOI:10.1021/om8009393

Several half-sandwich complexes of ruthenium with cyclopenta[J.] phenanthrenyl and cyclopen-ta[α]acenaphthylenyl ligands containing fused aromatic ring substituents on the cyclopentadienyl ring were prepared and characterized by NMR and X-ray crystallogra

Full text of DOI:10.1021/om8009393

598
Organometallics 2009, 28, 598–605
Cyclopenta[l]phenanthrenyl and Cyclopenta[a]acenaphthylenyl
Half-Sandwich Complexes of Ruthenium as Racemization Catalysts
for Secondary Alcohols
Denys Mavrynsky,† Reijo Sillanpa¨a¨,‡ and Reko Leino*,†
Laboratory of Organic Chemistry, Åbo Akademi UniVersity, FI-20500 Åbo, Finland, and Department of
Chemistry, UniVersity of JyVa¨skyla¨, FI-40351 JyVa¨skyla¨, Finland
ReceiVed September 27, 2008
Several half-sandwich complexes of ruthenium with cyclopenta[l]phenanthrenyl and cyclopen-
ta[a]acenaphthylenyl ligands containing fused aromatic ring substituents on the cyclopentadienyl ring
were prepared and characterized by NMR and X-ray crystallography. Activities of the complexes as
racemization catalysts for secondary alcohols were preliminarily screened by using (S)-phenylethanol as
the substrate. The catalytic activities of the fused-ring complexes depend strongly on the number of
other substituents in the five-membered ring and are inferior to those reported earlier for chlorodicar-
bonyl(pentaphenylcyclopentadienyl)ruthenium, currently considered as the best catalyst candidate for
dynamic kinetic resolution of secondary alcohols by combined enzyme/metal catalysis.
been reported in one case only: Hagiwara and co-workers
recently utilized the 1,2,3-triphenyl cyclopenta[l]phenanthrenyl
moiety as a ligand in their catalyst design for Suzuki-Miyara
coupling.7
Introduction
Dynamic kinetic resolution (DKR) of secondary alcohols
based on combined enzyme and metallocene catalysis was
originally developed more than 10 years ago.1 The use of
efficient organometallic catalysts for racemization allows one
to perform the resolutions under sufficiently mild conditions
required for enzyme functioning. In recent years, this approach
has been extensively investigated. Predominantly, pentasubsti-
tuted monocyclopentadienyl complexes of ruthenium have been
utilized as racemization catalysts for alcohols.2 Only a few
examples based on indenyl3 and aryl4 ruthenium complexes have
been described.
For further structural tuning as well as improvements in
activities and stabilities of the racemization catalysts, the
screening of new ligand modifications is desirable. Here, the
indenyl ligand platform provides a number of opportunities for
structural variation. Examples of transition metal complexes
containing fused-ring, polycylic indenyl-type ligands, such as
cyclopenta[l]phenanthrenyl5 and cyclopenta[a]acenaphthylenyl,6
are relatively scarce, but have been, in the context of catalytic
R-olefin polymerization (mainly M ) Zr),5b,c shown to result
in enhanced catalyst properties. To our knowledge, ruthenium
complexes containing cyclopenta[l]phenanthrenyl ligands have
In the present paper we describe our initial results in the use
of cyclopenta[l]phenanthrenyl and cyclopenta[a]acenaphthylenyl
ligands as structural motifs for alcohol racemization catalysts
with potential applications in DKR in combination with
enzymes. The resulting monocyclopentadienyl ruthenium com-
plexes combine the elements of the previously reported metal-
locene racemization catalysts containing polysubstituted Cp
ligands with a flat polycyclic part. The specific purpose of the
work was to investigate the relationships between the structures
and catalytic activities of such half-sandwich metallocene
complexes.
Results and Discussion
Synthesis and Characterization of the Catalysts and
Ligand Pecursors. The substituted cyclopenta[l]phenanthrenyl
ligand precursors 4a and 4b and the triphenyl-substituted
cyclopenta[a]acenaphthylenyl ligand precursor 7 were prepared
according to previously reported procedures.5a,8 The tert-
butyldimethylsiloxy-substituted ligand 4d was synthesized by
* Corresponding author. E-mail: reko.leino@abo.fi.
† Åbo Akademi University.
(5) (a) Schneider, N.; Prosenc, M.-H.; Brintzinger, H.-H. J. Organomet.
Chem. 1997, 545-546, 291. (b) Schneider, N.; Huttenloch, M. E.; Stehling,
U.; Kirsten, R.; Schaper, F.; Brintzinger, H. H. Organometallics 1997, 16,
3413. (c) Schneider, N.; Schaper, F.; Schmidt, K.; Kirsten, R.; Geyer, A.;
Brintzinger, H. H. Organometallics 2000, 19, 3597. (d) Luttikhedde, H. J. G.;
Leino, R.; Wile´n, C.-E.; Na¨sman, J. H. Polym. Prepr. (Am. Chem. Soc.,
DiV. Polym. Chem.) 1998, 39 (1), 229. (e) Rigby, S. S.; Decken, A.; Bain,
A. D.; McGlinchey, M. J. J. Organomet. Chem. 2001, 637-639, 372. (f)
Sun, J.; Berg, D. J.; Twamley, B. Organometallics 2008, 27, 683.
(6) (a) Repo, T.; Jany, G.; Hakala, K.; Klinga, M.; Polamo, M.; Leskela¨,
M.; Rieger, B. J. Organomet. Chem. 1997, 549, 177. (b) Aitola, E.; Hakala,
K.; Byman-Fagerholm, H.; Leskela¨, M.; Repo, T. J. Polym. Sci., Part A:
Polym. Chem. 2008, 46, 373.
‡ University of Jyva¨skyla¨.
(1) (a) Larsson, A. L. E.; Persson, B. A.; Ba¨ckvall, J.-E. Angew. Chem.,
Int. Ed. Engl. 1997, 36, 1211. For reviews, see: (b) Pa`mies, O.; Ba¨ckvall,
J.-E. Chem. ReV. 2003, 103, 3247. (c) Martín-Matute, B.; Ba¨ckvall, J.-E.
Curr. Opin. Chem. Biol. 2007, 11, 226.
(2) (a) Leijondahl, K.; Bore´n, L.; Braun, R.; Ba¨ckvall, J.-E. Org. Lett.
2008, 10, 2027. (b) Kim, M. J.; Choi, K. Y.; Kim, S.; Kim, D.; Han, K.;
Ko, S.-B.; Park, J. Org. Lett. 2008, 10, 1295. (c) Eckert, M.; Brethon, A.;
Li, Y.-X.; Sheldon, R. A.; Arends, I. W. C. E. AdV. Synth. Catal. 2007,
349, 2603. (d) Choi, J. H.; Choi, Y. K.; Kim, Y. H.; Park, E. S.; Kim, E. J.;
Kim, M. J.; Park, J. J. Org. Chem. 2004, 69, 1972.
(3) (a) Koh, J. H.; Jung, H. M.; Kim, M. J.; Park, J. Tetrahedron Lett.
1999, 40, 6281. (b) Xi, Q.; Zhang, W.; Zhang, X. Synlett 2006, 945.
(4) (a) Lee, D.; Huh, E. A.; Kim, J. M.; Jung, H. M.; Koh, J. H.; Park,
J. Org. Lett. 2000, 2, 2377. (b) Dijksman, A.; Elzinga, J. M.; Li, Y.-X.;
Arends, I. W. C. E.; Sheldon, R. A. Tetrahedron: Asymmetry 2002, 13,
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(7) Hoshi, T.; Nakazawa, T.; Saitoh, I.; Mori, A.; Suzuki, T.; Sakai,
J.-i.; Hagiwara, H. Org. Lett. 2008, 10, 2063.
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Komatsu, K.; Fujiura, R.; Okamoto, K. Chem. Lett. 1988, 265.
10.1021/om8009393 CCC: $40.75
2009 American Chemical Society
Publication on Web 12/15/2008

Half-Sandwich Complexes of Ruthenium
Organometallics, Vol. 28, No. 2, 2009 599
Scheme 1. Synthesis of the Ligand Precursors 4c and 4da
Scheme 2. Synthesis of the Ruthenium Complexes 6a-da
a
Conditions: (i) n-BuLi/THF, -78 °C to RT. (ii) [Ru(CO)3Cl2]2,
RT.
Scheme 3. Synthesis of the Ruthenium Complex 8a
a
Conditions: (i) Zn/AcOH, reflux. (ii) NaH, THF, RT. (iii) TBDM-
SCl, THF, RT. (iv) NaBH4, dioxane, reflux. (v) P2O5, benzene, reflux.
a
Conditions: (i) n-BuLi/THF, -78 °C to RT. (ii) [Ru(CO)3Cl2]2,
RT.
Scheme 4. Synthesis of the Ruthenium Complexes 6e and
6fa
Figure 1. Lithium salts of the cyclopenta[l]phenanthrenyl ligand
precursors 4c and 5.
silylation of the corresponding enolized ketone in a manner
similar to that reported earlier for 1,3-dihydro-2-oxocyclo-
penta[l]phenanthrene,5d 2-indanone, and its analogues (Scheme
1).9 The preparation of the diphenyl-substituted ligand precursor
4c is likewise illustrated in Scheme 1. A similar transformation
has been described earlier,10 where the authors claimed the
formation of the symmetrical 1,3-(diphenyl)cyclopenta[l]phenan-
threne 5. In our work, however, we observed a rearrangement
taking place leading to a mixture of the 1,3- and 1,2-substituted
products 5 and 4c in 1:3 ratio. A similar rearrangement in the
case of a trisubstituted analogue under acidic conditions has
been described earlier.11
a
Conditions: (i) Ru3(CO)12, mesitylene, 150 °C. (ii) RCOCl, toluene,
90 °C.
ligands were prepared by reactions of dichlorotricarbonylru-
thenium dimer with the corresponding ligand precursors depro-
tonated with butyllithium (Schemes 1 and 2). The fairly low
yields obtained represent the nonoptimized reaction conditions
for metalation. In all cases siginificant amounts of starting ligand
precursor were recovered during the reaction workup. Complex
6a is unstable, decomposing rapidly in solutions and slowly in
the solid state during storage at ambient temperature. All other
polysubstituted complexes are stable when stored in air.
The synthesis of the trisubstituted cyclopenta[l]phenanthrenyl
ruthenium complexes 6e and 6f containing an acyl substituent
in position 2 of the C5 ring commenced, in turn, from the
phencyclone precursor 1 followed by oxidative acylation of the
Ru(0) diene complex 9 with the corresponding acyl chlorides
(Scheme 4).
Structures of the compounds isolated here were also con-
firmed by NMR analysis of the corresponding anions. Upon
deprotonation with n-BuLi in THF-d8, compound 5 produced a
highly symmetrical anion, while compound 4c gave an unsym-
metrical structure (Figure 1). The position of the double bond
in 4c was likewise confirmed by NMR spectroscopy. The two
protons of the C5 ring give rise to two doublets (4J ) 1.1 Hz)
1
in the H NMR spectrum at 5.42 and 7.81 ppm, respectively.
In addition, a weak interaction (typical for allyl or W-coupling)
between these protons was observed in the COSY spectrum,
while a geminal coupling typical for a CH2 group was absent.
Next, the new ruthenium complexes 6a-d and 8 containing
cyclopenta[l]phenanthrenyl and cyclopenta[a]acenaphthylenyl
1
In the H NMR spectra of 6d and 6f two kinds of o- and
m-protons and carbons were observed indicating restricted
rotation of the phenyl rings. This rotation remained blocked in
VT NMR experiments at 50 °C. The lithium salt of 4d obtained
by deprotonation with n-BuLi, however, showed in the 1H NMR
spectrum time-averaged symmetry with only one type of o- and
m-protons and carbons (Figures 2 and 3). This observation may
be due to rapid rotation of the phenyl rings in solution at ambient
temperature, resulting in coinciding resonances. Another ex-
planation, however, is the potential lability of the ionically bound
lithium cation: a rapid exchange of Li+ transitorily bound on
(9) See for example: (a) Leino, R.; Luttikhedde, H.; Wile´n, C.-E.;
Sillanpa¨a¨, R.; Na¨sman, J. H. Organometallics 1996, 15, 2450. (b) Leino,
R.; Luttikhedde, H. J. G.; Lehtonen, A.; Sillanpa¨a¨, R.; Penninkangas, A.;
Strande´n, J.; Mattinen, J.; Na¨sman, J. H. J. Organomet. Chem. 1998, 558,
171. (c) Leino, R.; Luttikhedde, H. J. G.; Långstedt, L.; Penninkangas, A.
Tetrahedron Lett. 2002, 43, 4149.
(10) Kreicberga, J.; Neilands, O.; Kampars, V. Zh. Org. Khim. 1975,
11, 1941.
(11) Dennis, G. D.; Edward-Davis, D.; Field, L. D.; Masters, A. F.;
Maschmeyer, T.; Ward, A. J.; Buys, I. E.; Turner, P. Aust. J. Chem. 2006,
59, 135.

600 Organometallics, Vol. 28, No. 2, 2009
MaVrynsky et al.
Figure 2. Top views of 6d, 6f, and 4d-Li. Carbonyls and chlorine
are omitted for clarity.
one side of the ligand and the other (even being located in the
solvent independently from the anion) may also result in time-
averaging of the NMR signals without rotation about the C-Ph
bond.
Figure 4. Molecular structure of 6b (hydrogen atoms excluded for
clarity, 50% probability ellipsoids). Selected distances (Å): Ru-C1
2.281(3), Ru-C2 2.196(3), Ru-C3 2.253(3), Ru-C4 1.898(3),
Ru-C5 1.889(3), Ru-Cl 2.3988(7), Ru-Ct 1.899, C6-Pl1 0.078.
Ct is the C5 ring centroid. Pl1 is the plane calculated for the C5
ring and two other C6 rings.
X-ray Structures of Ruthenium Complexes. The molecular
structures of the ruthenium complexes 6b, 8, and 9 were
determined by X-ray crystallography and are elucidated, together
with selected bond lengths and angles, in Figures 4-6. The
ruthenium metal is η5-coordinated in complexes 6b and 8 (with
similar Ru-C bond distances to all carbon atoms of the five-
membered ring and η4-coordinated in complex 9 with the longest
Ru-C distance to the carbonyl carbon of the C5 ring. The
Ru-CO bond lengths are similar in all three complexes. In the
η5-coordinated complexes 6b and 8 the cyclopenta[l]phenan-
threnyl and cyclopenta[a]acenaphthylenyl moieties are nearly
planar. A small distortion from planarity for the terminal C6
ring of 6b is observed, possibly due to repulsion of the partial
negative charge on the ligand and the electronegative chlorine
atom. In the η4-diene complex 9 the ligand plane is significantly
distorted, with one terminal C6 ring tilted and the coordinated
C5 ring showing envelope geometry. The formal oxidation states
+2 for 6b and 8 and 0 for 9 are in good accordance with the
elongated Ru-carbonyl and Ru-C5 centroid distances in the
latter complex. The Ru-C5, Ru-carbonyl, and Ru-Cl distances
are similar to those in analogous complexes containing (pen-
taphenyl)cyclopentadienyl12 and (triphenyl)indenyl2d ligands.
Racemization of (S)-Phenylethanol. All ruthenium com-
plexes prepared from 6a-f and 8 were screened as catalysts
for the racemization of (S)-R-phenylethanol 10, a standard
reference substrate utilized for initial investigation of catalytic
activities in alcohol racemization and DKR (Scheme 5). The
racemization reactions were carried out in toluene at ambient
temperature by following the procedure described earlier by
Ba¨ckvall and co-workers.12
The unsubstituted cyclopenta[l]phenanthrenyl complex 6a was
found to be inefficient as a catalyst for the racemization reaction.
With this complex, the racemization stops at 70% ee after 2
days. Somewhat better activities were obtained with the mono-
and disubstituted complexes 6b and 6c. The racemization
remained, however, fairly low, with 50% ee reached only after
4 and 2 days of reaction, respectively. Only in the case of the
fully substituted complexes 6d and 8 were acceptable activities
obtained. The results are summarized in Figure 7.
The proposed mechanism for the racemization of secondary
alcohols catalyzed by monoCp-ruthenium complexes has been
1
Figure 3. H and HSQC-NMR of 6d and 4d-Li.

Half-Sandwich Complexes of Ruthenium
Organometallics, Vol. 28, No. 2, 2009 601
Figure 5. Molecular structure of 8 (hydrogen atoms excluded for
clarity, 50% probability ellipsoids). Selected distances (Å): Ru-C1
2.293(4), Ru-C2 2.284(4), Ru-C3 2.204(3), Ru-C4 1.874(5),
Ru-C5 1.902(5), Ru-Cl 2.4030(10), Ru-Ct 1.904. Ct is the closest
C5 ring centroid.
Figure 7. Racemization of (S)-phenylethanol catalyzed by 6d and
8 (1 mol %).
Scheme 6. Racemization of (S)-Phenylethanol
η5 to η3. It is well known that the stabilities of Cp complexes
generally increase with the increasing amount of substituents.13
It is conceivable that in the case of the less substituted complexes
6a-c the η3-coordinated intermediate of type 10 (Scheme 6)
might undergo further ring slippage and dissociation via η1-
coordination, leading to full decomposition of the catalyst. The
low stability of 6a in solution and the decomposition of 6b and
6c during the racemization reaction further support this hypoth-
esis. The complexes prepared can be arranged in a series
according to their phenylethanol racemization activities as 6a
< 6b < 6c , 6d, 8, clearly demonstrating increasing activities
with increasing number of C5 ring substituents. Only the fully
substituted complexes show acceptable activities. Accordingly,
our attention next turned to the bulkier catalyst variants 6e and
6f of this type.
Both complexes 6e and 6f show activities similar to 6d and
8 in the racemization of (S)-phenylethanol (Figure 8). The
2-benzoyl-substituted complex 6e performs better when com-
pared to its more congested adamantyl analogue 6f, indicating
that steric factors cannot be the only reason governing the
catalytic activities. It might be speculated that the pendant phenyl
functionality of the 2-benzoyl substituent may have a through-
space stabilizing, coordinative intereaction with the ruthenium
metal center. Similar intramolecular arene coordination is well
known for Ti- and Zr-based mono(cyclopentadienyl) olefin
polymerization catalysts.14
Figure 6. Molecular structure of 9 (hydrogen atoms excluded for
clarity, 50% probability ellipsoids). Selected distances (Å): Ru-C1
2.2673(17), Ru-C2 2.2139, Ru-C3 2.2186, Ru-C4 2.4896(18),
Ru-C5 2.220(7), Ru-C6 1.932(2), Ru-C7 1.936(2), Ru-C8
1.928(2), C4-O 1.227(2), Ru-Ct 1.919, C9-Pl1 0.493. Selected
angles (deg): Pl2-Pl3 17.96. Ct is the C5 ring centroid. Pl1 is the
plane calculated for the two flat C6 rings; Pl2 for C1, C2, C3, C4;
Pl3 for C3, C4, C5, O.
Scheme 5. Racemization of (S)-Phenylethanola
The racemization rates obtained with 6e are, however, slower
than those reported for the (pentaphenyl)cyclopentadienyl-based
complex 12 (0.5 mol % of catalyst, 50% ee reached after ca. 5
min), currently considered as the lead catalyst structure, under
similar reaction conditions.12 On the other hand, complex 13,
structurally similar to 6e, was by Park and co-workers reported
a
Conditions: (i) Catalyst 6a-f or 8 1 mol %, t-BuOK 3 mol %,
toluene, RT.
elucidated earlier by Ba¨ckvall and co-workers (Scheme 6). The
reaction involves a shift of hydrogen from the alcohol to
ruthenium accompanied by ring slippage of the Cp ring from

602 Organometallics, Vol. 28, No. 2, 2009
MaVrynsky et al.
Figure 10. Labeling of substituted cyclopenta[l]phenanthrenyl
fragments in the NMR spectral data.
neither extended investigations with other secondary alcohols
nor attempts to pursue dymanic kinetic resolutions in combina-
tion with enzymes were carried out with these catalysts. In the
present work, best performance was observed with a ligand
structure containing a pendant aromatic moiety (benzoyloxy).
Detailed NMR studies were carried out on a number of
complexes and their cyclopenta[l]phenanthrenyl ligand anion
lithium salts. Restricted rotation of phenyl substituents in the
ligand five-membered rings was observed in some cases when
moving from the lithium salts to transition metal coordination.
Figure 8. Racemization of (S)-phenylethanol catalyzed by 6e and
6f (1 mol %).
Experimental Section
General Remarks. All manipulations with air- and moisture-
sensitive compounds were performed under an inert atmosphere
of argon using standard Schlenk techniques. Solvents were pur-
chased from standard vendors and dried by standard procedures
(THF, benzene, toluene were redistilled from Na/benzophenone
ketyl, DCM was redistilled from calcium hydride, and pentane,
hexane, heptane were redistilled from sodium). NMR spectra were
recorded on a Bruker Avance 600 MHz spectrometer. Assignment
of NMR signals is based on 1DTOCSY, NOE-diff, COSY, and
HSQC experiments. Chiral GC analyses were performed on a HP
5890 series II gas chromatograph equipped with a Varian capillary
column CP7502. Phencyclone (1) was prepared according to a
litterature procedure.11,16 Solutions of anions of 4c,d and 5 in THF-
d8 were prepared directly in NMR tubes from the corresponding
cyclopentadienes and n-BuLi using syringe-septum techniques. (S)-
R-Phenylethanol was obtained by enzymatic kinetic resolution of
the racemate and purified by column chromatography. Com-
mercially available (S)-R-phenylethanol (Aldrich, 97%) yielded
unreproducible results. Potassium tert-butoxide, required for activa-
tion of the racemization catalyst, should be freshly sublimated in
order to obtain reproducible results.
Figure 9. Structures of complexes 12 and 13 (structural analogues
of 6e).
to provide similar activities at 4 mol % concentration15 to those
observed here for 6e at 1 mol % loading (for structures of 12
and 13, see Figure 9).
The results obtained here may nevertheless be considered
promising, clearly demonstrating variable racemization perfor-
mance as a function of the ligand sterics, providing structure/
reactivity trends to aid in future catalyst design.
Summary and Conclusions
To summarize, a series of half-sandwich ruthenium complexes
with substituted cyclopenta[l]phenanthrenyl and cyclopen-
ta[a]acenaphthylenyl ligands were prepared and characterized
by NMR and in three cases by X-ray crystallography. The
catalytic activities of the complexes in racemization of (S)-
phenylethanol were investigated and were shown to depend
strongly on the substitution pattern of the ligand framework.
Acceptable racemization results were obtained with fully
substituted complexes only. The racemization activities were,
however, lower than those reported for chlorodicarbonyl(pen-
taphenyl)cyclopentadienylruthenium (12), currently considered
as the best-performance catalyst for secondary alcohol racem-
ization in DKR applications with enzymes. For this reason,
The following labeling of the cyclopenta[l]phenanthrene deriva-
tives was applied in the assignment of NMR signals (Figure 10):
General Procedures for Preparation of the Complexes
6a-d and 8. A solution of ligand precursor 1a-d or 3 (0.5 mmol)
in 3 mL of THF was cooled to -78 °C followed by addition of
0.31 mL (0.5 mmol) of a 1.6 M solution of n-BuLi in hexane via
syringe. The reaction mixture was stirred for 15 min at -78 °C
and allowed to warm to RT. Next, a solution of tricarbonyldichlo-
roruthenium(II) dimer (128 mg, 0.25 mmol) in 2 mL of THF was
added via syringe. The mixture was stirred for 2 h at RT, then
evaporated with silica and purified by column chromatography using
DCM-hexane as eluent. All products were obtained as yellow
(6a-d) or brown (8) microcrystalline powders. Yields: 6a 30%,
6b 30%, 6c 26%, 6d 7%, 8 27%.
(12) Mart´ın-Matute, B.; Edin, M.; Boga´r, K.; Kaynak, B.; Ba¨ckvall, J.-
E. J. Am. Chem. Soc. 2005, 127, 8817.
(13) (a) Heeg, M. J.; Janiak, C.; Zuckerman, J. J. J. Am. Chem. Soc.
1984, 106, 4529. (b) Bercaw, J. E.; Marvich, R. H.; Bell, L. G.; Brintzinger,
H. H. J. Am. Chem. Soc. 1972, 94, 1219. (c) Miller, E. J.; Landon, S. J.;
Brill, T. B. Organometallics 1985, 4, 533. (d) Calabro, D. C.; Hubbard,
J. L.; Blevins, C. H.; Campbell, A. C.; Lichtenberger, D. L. J. Am. Chem.
Soc. 1981, 103, 6839.
(14) (a) Sassmannshausen, J.; Powell, A. K.; Anson, C. E.; Wocadlo,
S.; Bochmann, M. J. Organomet. Chem. 1999, 592, 84. (b) Deckers, P. J. W.;
Hessen, B.; Teuben, J. H. Angew. Chem. 2001, 40, 2516. (c) Deckers,
P. J. W.; Hessen, B.; Teuben, J. H. Organometallics 2002, 21, 5122.
(15) Kim, N.; Ko, S.-B.; Kwon, M. S.; Kim, M.-J.; Park, J. Org. Lett.
2005, 7, 4523.
Chlorodicarbonyl(η5-cyclopenta[l]phenanthryl)ruthenium(II) (6a).
1H NMR (CDCl3, 600.13 MHz): δ 5.82 (t, 3J ) 2.7 Hz 1H, Cp-H),
3
3
5.95 (d, J ) 2,7 Hz, 2H, Cp-H), 7.66 (dd, J ) 7.2, 7.9 Hz, 2H,
3-H), 7,72 (ddd, 2H, 3J ) 8.4, 7.2, 4J ) 1.4, 2-H), 7.98 (dd, 2H, 3J
(16) Wooi, G. Y.; White, J. M. Org. Biomol. Chem. 2005, 3, 972.

Half-Sandwich Complexes of Ruthenium
Organometallics, Vol. 28, No. 2, 2009 603
4
3
) 7.9, J ) 1.4 Hz, 4-H), 8.54 (d, J ) 8.4 Hz, 1-H). 13C NMR
(CDCl3, 150.9 MHz): δ 72.34 (Cp), 89.59 (Cp), 107.30, 124.28,
125.02, 125.42, 128.26, 129.35, 131.15, 195.76 (CdO). MS: exact
mass calcd. for C19H11102Ru35ClO2 407.9491, found 407.9490; 380
(M+ - CO), 352 (M+ - 2CO).
to RT, the mixture was diluted with 5 mL of hexane. The precipitate
was separated by filtration, redissolved in 10 mL of toluene, and
separated from a small amount of insoluble byproduct 2 by filtration.
Finally, 0.7 g (82%) of 9 was obtained as a greenish microcrystalline
1
3
solid. H NMR (CDCl3, 600.13 MHz): δ 7.26 (dd, J ) 8.2, 7.6
3
3
Chlorodicarbonyl(η5-2-phenylcyclopenta[l]phenanthryl)ruth-
Hz, 2H, 3-H), 7.45 (d, J ) 8.2 Hz, 2H, 4-H), 7.48 (dd, J ) 8.2,
8.0 Hz, 2H, m-Ph), 7.49 (dd, 3J ) 8.2, 7.5 Hz, 2H, m-Ph), 7.54 (d,
3J ) 8.0 Hz, 2H, o-Ph), 7.55 (d, 3J ) 7.5 Hz, 2H, o-Ph), 7.57 (dd,
1
enium(II) (6b). H NMR (CDCl3, 600.13 MHz): δ 6.34 (s, 2H,
Cp-H), 7.46 (dd, 3J ) 8.0, 6.6 Hz, 2H, m-Ph), 7.47 (t, 3J ) 6.6 Hz,
3J ) 8.2, 7.6 Hz, 2H, 2-H), 7.58 (t, J ) 8.2 Hz, 2H, p-Ph), 8.52
3
1H, p-Ph), 7.66 (d, 3J ) 8.0 Hz, 2H, o-Ph), 7.68 (dd, 3J ) 7.8, 7.7
(d, 3J ) 8.2 Hz, 2H, 1-H). 13C NMR (CDCl3, 150.9 MHz): δ 82.14
(cyclopentadienone), 97.54 (cyclopentadienone), 124.06 (1-C),
126.00, 126.50 (4-H), 127.87 (3-H), 128.34 (m-Ph), 128.86 (m-
Ph), 128.92 (1-H), 129.42 (p-Ph), 130.94, 131.33 (o-Ph), 132.83,
134.75 (o-Ph), 177.58 (dC-CO-Cd), 193.64 (CdO). MS: exact
mass calcd for C32H19102RuO4(+H) 569.0327, found 569.0330; exact
mass calcd for C32H19102RuO4(+H - CO) 541.0378, found 541.0394;
exact mass calcd for C32H19102RuO4(+H - 2CO) 513.0429, found
513.0410.
3
4
Hz, 2H, 3-H), 7.72 (ddd, J ) 8.0, 7.7 Hz, J ) 1,1 Hz, 2H, 2-H)
3
4
3
8.06 (dd, J ) 7.8, J ) 1.1 Hz, 2H, 4-H), 8.54 (d, J ) 8.0 Hz,
2H, 1-H). 13C NMR (CDCl3, 150.9 MHz): δ 69.46 (Cp-C), 106.01,
113.69, 124.31 (1-C), 125.19, 125.34 (4-C), 126.82 (o-C), 128.25
(2-C), 129.18 (p-C), 129.25 (3-C), 130.05, 130.28 (m-C), 131.10,
195.60 (CdO). MS: exact mass calcd for C25H15102Ru35ClO2
483.9804, found 483.9600; 455.97 (M+-CO), 427.97 (M+ - 2CO).
Chlorodicarbonyl(η5-1,2-diphenylcyclopenta[l]phenan-
thryl)ruthenium(II) (6c). 1H NMR (CDCl3, 600.13 MHz): δ 7.22
3
General Procedures for Preparation of the Complexes 6e and
6f. A mixture of 57 mg (0.1 mmol) of 9, 0.1 mmol of the
corresponding acyl chloride, and 2 mL of toluene was heated at 90
°C for 12 h. The solvent was evaporated and the residue purified
by column chromatography using DCM-hexane as eluent. The
products were obtained as yellow microcrystalline solids. Yields:
6e 15%, 6f 27%.
(ur, 1H, Ph), 7.23 (d, J ) 7.0 Hz, 1H, o-Ph(c)), 7.26-7.30 (m,
3H, Ph), 7.27 (d, 3J ) 7.0 Hz, 1H, o-Ph (c)), 7.35 (d, 3J ) 8.0 Hz,
3
1H, o-Ph (d)), 7.40 (ur, 1H, Ph), 7.43 (d, J ) 8.0 Hz, 1H, o-Ph
3
(d)), 7.52 (dd, J ) 7.6, 7.6 Hz, 1H, 2b- or 3b-H), 7.60 (ur, 1H,
3
3
Ph), 7.61 (dd, J ) 7.6, 7.6 Hz, 1H, 2b- or 3b-H), 7.70 (dd, J )
3
7.8, 7.8 Hz, 1H, 2a- or 3a-H), 7.73 (dd, J ) 7.8, 7.8 Hz, 1H, 2a-
3
3
or 3a-H), 7.97 (d, J ) 7.6 Hz, 1H, 4b-H), 8.12 (d, J ) 7.8 Hz,
1H, 4a-H), 8.54 (d, 3J ) 7.6 Hz, 1H, 1b-H), 8.55 (d, 3J ) 7.8, 1H,
1a-H). 13C NMR (CDCl3, 150.9 MHz): δ 70.94 (Cp), 95.68 (Cp),
103.32, 105.72, 116.06, 124.16 (1a-C), 124.18 (1b-C), 125.05,
125.36 (4a-C), 125.89, 126.52 (o-Ph), 127.64 (Ph), 128.23 (2a- or
3a-C), 128.35 (2 carbons, o-Ph), 128.80 (Ph), 128.99 (Ph), 129.12
(2b- or 3b-C), 129.22 (2a- or 3a-C), 129.25 (o-Ph), 129.45 (Ph),
129.76 (2b- or 3b-C), 129.98, 131.11, 131.25 (o-Ph), 131.72, 132.18,
134.71 (4b-C), 196.04 (CdO), 196.29 (CdO). MS: exact mass
calcd for C31H19102Ru35ClO2(+Na) 583.0015, found 583.0010; exact
mass calcd for C31H19102Ru35ClO2(+K) 598.9754, found 598.9727.
Chlorodicarbonyl(η5-2-benzoyloxy-1,3-diphenylcyclopenta[l]-
phenanthryl)ruthenium(II) (6e). 1H NMR (CDCl3, 600.13 MHz):
3
3
δ 7.30 (dd, J ) 8.1, 7.5 Hz, 2H, m-Bz), 7.33 (dd, J ) 7.5, 7.8
3
3
Hz, 2H, 3-H), 7.37 (dd, J ) 8.2, 8.0 Hz, 2H, m-Ph), 7.41 (dd, J
) 8.2, 7.6 Hz, 2H, m-Ph), 7.49 (t, 3J ) 8.0 Hz, 2H, p-Ph), 7.49 (t,
3J ) 7.5 Hz, 2H, p-Bz), 7.59 (d, J ) 8.2 Hz, 2H, o-Ph), 7.59 (d,
3
3J ) 7.5 Hz, 2H, o-Ph) 7.62 (dd, 3J ) 8.2, 7.8 Hz, 2H, 2-H), 7.70
3
3
(d, J ) 7.9 Hz, 2H, o-Bz), 7.92 (d, J ) 7.5 Hz, 2H, 4-H), 8.54
(d, 3J ) 8.2 Hz, 2H, 1-H). 13C NMR (CDCl3, 150.9 MHz): δ 89.31
(Cp), 99.06 (Cp), 124.09 (1-C), 125.06, 126.91 (o-Ph), 127.69 (3-
C), 128.51 (m-Bz), 128.63 (m-Ph), 128.78, 129.01(2-C), 129.29
(m-Ph), 129.38 (p-Ph), 129.97 (o-Bz), 131.40 (o-Ph), 131.58,
133.35, 133.57 (4-C), 134.16 (p-Bz), 163.24 (Ph-CdO), 195.61
(CdO). MS: exact mass calcd for C38H23102Ru35ClO4(+Na) 703.0226,
found 703.0227.
Chlorodicarbonyl(η5-2-(tert-butyldimethylsiloxy)-1,3-diphenyl-
cyclopenta[l]phenanthryl)ruthenium(II) (6d). H NMR (CDCl3,
1
600.13 MHz): δ -0.55 (s, 6H, Si-CH3), 0.46 (s, 9H, t-Bu), 7.27
3
3
(t, J ) 7.7 Hz, 2H, p-Ph), 7.44 (d, J ) 8.5 Hz, 2H, o-Ph), 7.45
3
3
(dd, J ) 7.7, 8.5 Hz, 2H, m-Ph), 7.50 (d, J ) 8.5, 2H, o-Ph),
7.51 (dd, 3J ) 7.7, 8.5 Hz, 2H, m-Ph), 7.55 (dd, 3J ) 8.1, 7.6 Hz,
Chlorodicarbonyl(η5-2-adamantanoyloxy-1,3-diphenylcyclopen-
ta[l]phenanthryl)ruthenium(II) (6f). 1H NMR (CDCl3, 600.13
MHz): δ 1.28 (d, 3J ) 2.5 Hz, 6H, R-adamantyl-H). 1.46 (d, 2J )
3
3
2H, 2-H), 7.62 (dd, J ) 7.6, 7.6 Hz, 2H, 3-H), 8.01 (d, J ) 7.6
Hz, 2H, 4-H), 8.49 (d, J ) 8.1 Hz, 2H, 1-H). 13C NMR (CDCl3,
3
2
150.9 MHz): δ -4.65 (Si-CH3), 18.01 (C(CH3)3), 24.87 (C(CH3)3),
86.00, 123.86 (1-C), 125.62, 126.99 (o-Ph), 127.35 (p-C), 128.39
(2-C), 128.44 (m-Ph), 129.22 (m-Ph), 129.93 (3-C), 130.39, 131.10,
131.68 (o-Ph), 135.42 (4-C), 196.49 (CdO). MS: exact mass calcd
for C37H33102Ru35ClO3(+Na) 713.0829, found 713.0802; exact mass
calcd for C37H33102Ru35ClO3(+Na - CO) 685.0880, found 685.0860.
12.5 Hz, 3H, equatorial δ-adamantyl-H), 1.57 (d, J ) 12.5 Hz,
3H, axial δ-adamantyl-H), 1.80 (t, 3J ) 2.5 Hz, 3H, ꢀ-adamantyl-
3
3
H), 7.32 (dd, J ) 8.2, 7.5 Hz, 2H, 2-H), 7.42 (t, J ) 7.2 Hz,
p-Ph), 7.50 (dd, 3J ) 8.1, 7.2 Hz, 2H, m-Ph), 7.51 (d, J ) 8.1, 2H,
3
3
o-Ph), 7.56 (dd, J ) 8.1, 7.2, 2H, m-Ph), 7.60 (d, J ) 8.1 Hz,
2H, o-Ph), 7.61 (dd, 3J ) 7.5, 7.5 Hz, 2H, 3-H), 7.84 (d, 3J ) 7.5
Hz, 2H, 4-H), 8.54 (d, J ) 8.2 Hz, 2H, 1-H). 13C NMR (CDCl3,
3
Chlorodicarbonyl(η5-1,2,3-triphenylcyclopenta[a]acenaphth-
ylenyl)ruthenium(II) (8). 1H NMR (CDCl3, 600.13 MHz): δ 7,17
(ur, 2H, Ph), 7.24-7.27 (m, 1H, Ph), 7.35-7.39 (m, 6H, Ph), 7.54
150.9 MHz): δ 27.39 (ꢀ-adamantyl-C), 35.98 (δ-adamantyl-C, a,e),
37.85 (R-adamantyl-C), 40.52 (γ-adamantyl-C), 88.97 (Cp), 99.68
(Cp), 124.06 (1-C), 125.07, 126.93 (o-Ph), 127.65 (1-C), 128.51
(p-Ph), 128.89, 128.95 (4-C), 129.22 (2 carbons, m-Ph), 131.66
(o-Ph), 131.58, 133.22, 133.78 (3-C), 174.12 (Ad-CdO), 195.55
(CdO). MS: exact mass calcd for C42H33102Ru35ClO4(+Na) 761.1009,
found 761.0999, exact mass calcd for C42H33102Ru35ClO4(+K)
777.0748, found 777.0728.
(dd, 3J ) 7.1, 8.1 Hz, 2H, 2-H) 7.55-7.57 (m, 4H), 7.79 (d, J )
3
7.1 Hz, 2H, 3-H), 7.89 (d, 3J ) 8.1 Hz, 2H, 1-H). 13C NMR (CDCl3,
150.9 MHz): δ 100.38 (Cp), 106.77 (Cp), 108.06, 123.19 (3-C),
128.00 (1-C), 128.15 (Ph), 128.20 (2-C), 128.48 (Ph), 128.65 (Ph),
129.11 (Ph), 129.66, 129.90, 130.26, 130.68 (Ph), 130.77, 132.21
(Ph), 138.53, 197.03 (CdO). MS: exact mass calcd for
C35H21102Ru35ClO2(+Na) 633.0171, found 633.0167; exact mass
calcd for C35H21102Ru35ClO2(+K) 648.9911, found 648.9892.
1,3-Dihydro-1,3-diphenyl-2H-cyclopenta[l]phenanthren-2-one (2,5-
dihydrophencyclone) (2). A suspension of 1.91 g (5 mmol) of
phencyclone 1 and 0.98 g (15 mmol) of zinc powder in 50 mL of
glacial acetic acid was refluxed until the green color of 5
dissappeared (ca. 2 h). The mixture was evaporated, and the residue
boiled with 200 mL of xylene and filtered hot from zinc powder.
Xylene was evaporated, the residue was suspended in a small
amount of DCM, and the precipitate was separated by filtration
giving fraction A, enriched in the cis-isomer. The filtrate was
Tricarbonyl(η4-1,3-diphenylcylopenta[l]phenanthren-2-one)ru-
thenium(0) (9). A mixture of 0.76 g (2 mmol) of phencyclone (5),
0.32 g (0.5 mmol) of triruthenium dodecacarbonyl, and 5 mL of
mesitylene was heated to 150 °C with stirring for 24 h. The reaction
mixture was cooled to RT, and argon was bubbled through the
mixture to remove the carbon monoxide released followed by
heating at the same temperature for an additional 4 h. After cooling

604 Organometallics, Vol. 28, No. 2, 2009
MaVrynsky et al.
evaporated, the residue was suspended in a small amount of acetone,
and the precipitate formed was separated by filtration, giving
fraction B, enriched in the trans-isomer. Configurational assignment
of the NMR spectra has been reported earlier.17 trans-2 was
obtained as a mixture with cis-2 with some NMR signals overlap-
lated: 30 mg (11%) of 5 (first band, dark blue in UV) and 85 mg
(30%) of 4c (second band, bright blue in UV) as white solids. 4c
4
1H NMR (CDCl3, 600.13 MHz): δ 5.37 (d, J ) 1.1 Hz, Cp-H),
3
3
7.07 (t, J ) 7.3 Hz, 1H, p-Ph), 7.14 (dd, J ) 7.9, 7.3 Hz, 2H,
3
3
m-Ph), 7.18 (t, J ) 7.3 Hz, 1H, p-Ph), 7.20 (d, J ) 7.9 Hz, 2H,
1
3
3
ping. Total yield: 1.14 g (60%). cis-2 H NMR (CDCl3, 600.13
o-Ph), 7.29 (dd, J ) 8.4, 7.3 Hz, 2H, m-Ph), 7.38 (dd, J ) 8.0,
7.5 Hz, 1H, 3b-H), 7.46 (dd, 3J ) 8.3, 7.5 Hz, 1H, 2b-H), 7.61 (d,
MHz): δ 5.20 (s, 2H, Ph-CH), 7.17-7.27 (m, 8H, Ph), 7.49 (dd, 3J
) 8.1, 7.0, 2H phenanthrene-H), 7.58 (d, 3J ) 8.1 Hz, 2H,
3J ) 8.4 Hz, 1H, o-Ph), 7.66 (dd, J ) 7.8, 8.0 Hz, 1H, 2a-H),
3
3
3
4
phenanthrene-H), 7.68 (dd, J ) 8.4, 7.0, 2H, phenanthrene-H),
7.69 (dd, J ) 7.8, 8.3 Hz, 1H, 3a-H), 7.76 (d, J ) 1.1 Hz, 1H,
Cp-H), 7.83 (d, 3J ) 8.0 Hz, 1H, 4b-H), 8.28 (d, 3J ) 8.0 Hz, 1H,
4a-H), 8.64 (d, 3J ) 8.3 Hz, 1H, 1b-H), 8.71 (d, 3J ) 8.3 Hz, 1H,
1a-H). 13C NMR (CDCl3, 150.9 MHz): δ 57.42 (Cp-CH), 123.38
(1a-C), 123.44 (1b-C), 123.86 (4b-C), 124.63 (4a-C), 124.69 (Cp-
CH), 125.25 (2b-C), 126.20 (2a-C), 126.59 (o-Ph), 126.63 (3a-C),
126.70 (p-Ph), 126.73 (3b-C), 127.35 (p-Ph), 128.50 (m-Ph), 128.52
(o-Ph), 128.84 (m-Ph), 128.86, 129.44, 130.76, 135.15, 138.96,
139.48, 143.13, 153.20. Due to complexity of the spectrum, one
signal corresponding to a quaternary carbon atom is not visible.
8.82 (d, 3J ) 8.4 Hz, 2H, phenanthrene-H). 13C NMR (CDCl3, 150.9
MHz): δ 58.93, 123.38, 126.52, 126.95, 127.12, 127.27, 128.17,
1
128.56, 128.76, 131.21, 135.53, 137.37, 210.55. trans-2 H NMR
(CDCl3, 600.13 MHz): δ 5.26 (s, 2H, Ph-CH), 7.14-7.29 (m, 8H,
3
Ph-H), 7.49 (ur, 2H), 7.58 (d, J ) 8.0 Hz, 2H), 7.69 (ur, 2H),
3
8.79 (d, J ) 8.4 Hz, 2H).
2-(tert-Butyldimethylsiloxy)-(1,3-diphenyl)cyclopenta[l]phenan-
threne (4d) and 2-(tert-Butyldimethylsiloxy)(1,3-diphenyl)cyclo-
penta[l]phenanthrenyllithium (4d-Li). A suspension of 100 mg
(0.26 mmol) of 2 (mixture of isomers) and 40 mg (1 mmol) of
60% sodium hydride in mineral oil in 3 mL of THF was stirred
overnight. Then 75 mg (0.5 mmol) of TBDMSCl was added, and
the obtained clear solution was stirred for 24 h. The reaction mixture
was distributed between chloroform and water, the organic phase
was separated, dried over sodium sulfate, and evaporated, and the
residuewaspurifiedbycolumnchromatography(eluentDCM-hexane).
4d (85 mg, 66%) was obtained as an oil, solidifying upon storage.
1H NMR (CDCl3, 600.13 MHz): δ -0.34 (s, 3H, Si-CH3), -0.11
(s, 3H, Si-CH3), 0.66 (s, 9H, tBu), 4.80 (s, 1H, Cp-H), 7.19-7.22
(m, 1H), 7.26-7.28 (m, 5H), 7.37 (ur, 1H), 7.40-7.55 (m, 8H),
1
Compound 4c-Li: H NMR (THF-d8, 600.13 MHz): δ 6.71 (t,
3
3J ) 7.3 Hz, 1H, p-Ph), 6.79 (dd, J ) 8.1, 7.4 Hz, 1H, 3b-H),
3
6.83 (dd, J ) 8.1, 7.4 Hz, 1H, 2b-H), 6.85 (s, 1H, Cp-H), 6.91
3
3
(dd, J ) 8.1, 7.4 Hz, 1H, 2a-H), 6.91 (dd, J ) 8.2, 7.3 Hz, 2H,
m-Ph), 7.10 (t,
3J ) 7.3 Hz, 1H, p-Ph), 7.15 (dd, 3J ) 8.1, 7.4 Hz,
1H, 3a-H), 7.18 (d, 3J ) 8.2 Hz, 2H, o-Ph), 7.20 (dd, 3J ) 8.0, 7.3
Hz, 2H, m-Ph), 7.37 (d, 3J ) 8.0 Hz, 2H, o-Ph), 7.78 (d, 3J ) 8.1
Hz, 1H, 4b-H), 8.07 (d, 3J ) 8.1 Hz, 1H, 4a-H), 8.26 (d, 3J ) 8.1
Hz, 1H, 1a-H), 8.27 (d, 3J ) 8.1 Hz, 1H, 1b-H). 13C NMR (THF-
d8, 150.9 MHz): δ 98.74 (Cp-CH), 115.24, 117.62 (2b-C), 117.93
(2a-C), 120.64 (p-Ph), 121.33, 121.37 (4a-C), 122.17 (1b-C), 122.23
(1a-C), 122.79 (4b-C), 123.00 (p-Ph), 123.37 (3b-C), 124.06, 124.18
(3a-C), 124.96, 125.94, 126.59 (m-Ph), 127.11 (m-Ph), 127.63,
127.75 (o-Ph), 132.39 (o-Ph), 133.01, 133.74.
3
3
7.72 (d, J ) 8.3 Hz, 2H, 4-H), 8.64 (d, J ) 8.2 Hz, 1H, 1-H),
8.72 (d, 3J ) 8.2 Hz, 1H, 1-H). 13C NMR (CDCl3, 150.9 MHz): δ
-4.62 (Si-CH3), -4.23 (Si-CH3), 18.08 (Si-C(CH3)3), 25.40 (Si-
C(CH3)3), 56.01 (Cp, C-O-Si), 122.42, 123.20, 123.24, 123.38,
124.32, 125.44, 125.49, 125.59, 126.58, 126.98, 127.33, 127.84,
128.56, 128.76, 128.90, 131.06, 134.34, 136.31, 138.41, 138.71,
162.72.
1
3
Compound 5: H NMR (CDCl3, 600.13 MHz): δ 5.09 (d, J )
3
1.8 Hz, 1H, Cp-H), 6.58 (d, J ) 1.8 Hz, 1H, Cp-H), 7.16 (ur,
2H), 7.20 (ur, 1H), 7.26 (ur, 2H), 7.34 (ur, 1H), 7.40-7.48 (m,
3
3
4H), 7.58 (ur, 1H), 7.75 (d, J ) 8.2 Hz, 1H, 4-H), 7.86 (d, J )
8.2 Hz, 1H, 4-H), 8.71 (d, 3J ) 8.2 Hz, 1H, 1-H), 8.76 (d, 3J ) 8.2
Hz, 1H, 1-H). 13C NMR (CDCl3, 150.9 MHz): δ 55.70 (Cp-CH),
123.25, 123.34, 124.86, 125.33, 125.55, 125.75, 125.88, 126.67,
126.79, 127.55, 128.03, 128.12, 128.32, 128.84, 128.97, 129.66,
131.21, 138.27, 138.73, 139.14, 140.73, 143.25, 145.15. Due to
complexity of the spectrum, one signal corresponding to a
quaternary carbon atom is not visible.
4d-Li. 1H NMR (THF-d8, 600.13 MHz, aromatic part): δ
3
6.83δ6.86 (m, 4H, 2- and 3-H), 6.97 (t, J ) 7.3 Hz, 2H, p-Ph),
3
3
7.21 (dd, J ) 7.9, 7.3 Hz, 4H, m-Ph), 7.59 (d, J ) 7.9 Hz, 4H,
o-Ph), 8.20-8.22 (m, 2H, 4-H), 8.33-8.35 (m, 2H, 1-H). 13C NMR
(THF-d8, 150.9 MHz, aromatic part): δ 105.50, 113.58, 116.91(2-
or 3-C), 121.84 (p-Ph), 122.02 (1-C), 122.52 (2- or 3-C), 123.15
(4-C), 124.07, 125.17, 126.61 (m-Ph), 132.29 (o-Ph), 132.43,
143.67.
1
Compound 5-Li: H NMR (THF-d8, 600.13 MHz): δ 6.39 (s,
3
2,3-Dihydro-1,3-diphenyl-1H-cyclopenta[l]phenanthren-2-ol (3).
Sodium borohydride (0.4 g, 10 mmol) was added to a boiling
suspension of 0.5 g (1.3 mmol) of 2 (mixture of isomers) in dioxane.
The mixture was refluxed for 1 h, cooled to RT, quenched with
5% HCl, and evaporated. The residue was treated with DCM, and
the insoluble portion was filtered off. The filtrate was evaporated.
3 (0.47 g, 94%; mixture of stereoisomers) was obtained as a white
1H, Cp-H), 6.90 (ur, 2H, 2-H), 6.91 (t, J ) 7.0 Hz, 2H, p-Ph),
6.92 (ur, 2H, 3-H), 7.16 (dd, 3J ) 7.0, 7.4 Hz, 4H, m-Ph), 7.58 (d,
3J ) 7.4 Hz, 4H, o-Ph), 8.32 (d, 3J ) 7.7 Hz, 2H, 4-H), 8.33 (d, 3J
) 7.7 Hz, 2H, 1-H). 13C NMR (THF-d8, 150.9 MHz): δ 117.86,
117.87, 117.89 (2-C), 121.29 (p-Ph), 122.23 (1-C + Cp-CH), 123.09
(3-C), 123.20 (4-C), 126.02, 126.87 (m-Ph), 128.57 (o-Ph), 133.25,
145.72.
1
powder. H NMR (CDCl3, 600.13 MHz): δ 4.77-4.82 (m, 1H),
General Procedure for the Racemization Reactions. Potassium
tert-butoxide (0.7 mg, 6 µmol) and 2 µmol of complex (6a-f or
8) were mixed in 1 mL of toluene. The mixture was stirred for 5
min at RT. Then a solution of 24 mg (200 µmol) of (S)-R-
phenylethanol 10 in 1 mL of toluene was added. Derivatization of
samples (propionic anhydride in the presence of pyridine and
DMAP) was performed in order to achieve a better resolution and
to stop the racemization process. The ratio of the enantiomers
formed was determined by chiral GC (oven temperature 100 °C,
retention times 10.13 min (S) and 11.30 min (R)).
5.20-5.22 (m, 1.5H), 5.35-5.39 (m, 0.5 H), 7.14-7.21 (m, 7H),
7.29-7.33 (m, 2H), 7.38-7.42 (m, 2H), 7.46-7.55 (m, 2H),
3
3
7.61-7.66 (m, 3H), 8.76 (d, J ) 8.3 Hz, 1H), 8.80 (d, J ) 8.3
Hz, 1H).
1,2-Diphenylcyclopenta[l]phenanthrene (4c), 1,2-diphenylcyclo-
penta[l]phenanthrenyllithium (4c-Li), 1,3-diphenylcyclopenta[l]-
phenanthrene (5), and 1,3-diphenylcyclopenta[l]phenanthre-
nyllithium (5-Li). Phosphorus pentoxide (0.3 g, 2 mmol) was added
to a boiling solution of 0.3 g (0.78 mmol) of 3 in 30 mL of benzene.
The mixture was refluxed for 5 min, cooled to RT, washed with
water, and evaporated. The residue was purified by column
chromatography (eluent DCM-hexane). Two fractions were iso-
Acknowledgment. Financial support from the Finnish
Funding Agency for Technology and Innovation (Technology
Programme SYMBIO Project #40168/07: Developing New
Chemoenzymatic Methods and Biocatalysts) is gratefully
acknowledged. The authors thank Prof. Liisa Kanerva and
(17) Schuster, I. I.; Craciun, L.; Ho, D. M.; Pascal, R. A., Jr. Tetrahedron
2002, 58, 8875.

Half-Sandwich Complexes of Ruthenium
Organometallics, Vol. 28, No. 2, 2009 605
Supporting Information Available: X-ray diffraction data for
complexes 4b, 8, and 9 in CIF format and copies of NMR spectra
of the complexes prepared. This material is available free of charge
via the Internet at http://pubs.acs.org.
Mari Pa¨ivio¨ (University of Turku) for fruitful discussions
and for providing the (S)-R-phenylethanol utilized in the
racemization experiments. Markku Reunanen is thanked for
recording the HRMS analyses. We also thank the reviewers
of this paper for their valuable suggestions and comments
on improving the manuscript.
OM8009393