Reactions of (η5-indenyl)Ru(PPh3)2Cl with CH2Cl2 and CHCl3: Formation of (η5-indenyl)Ru{CH2PPh2 (C6H4)} (PPh3) and (η5-indenyl)Ru(PPh3)(CO)Cl

Article abstract of DOI:10.1021/om001003n

A cyclic phosphorus ylide complex, (η⁵-indenyl) Ru{CH₂PPh₂(C₆H₄)}(PPh₃) (2), and (η⁵-indenyl)-Ru(PPh₃)(CO)Cl (3) were formed in the reactions of (η⁵-indenyl)Ru(PPh₃)₂Cl (1) with CH₂Cl₂ and CHCl₃ in the presence of KOH and 2-propanol, respectively.

Full text of DOI:10.1021/om001003n

1892
Organometallics 2001, 20, 1892-1894
Rea ction s of (η5-In d en yl)Ru (P P h 3)2Cl w ith CH2Cl2 a n d
CHCl3: F or m a tion of
(η5-In d en yl)Ru {CH2P P h 2(C6H4)}(P P h 3) a n d
(η5-In d en yl)Ru (P P h 3)(CO)Cl
J ung Hye Park, J eong Hwan Koh, and J aiwook Park*
Department of Chemistry, Center for Integrated Molecular System, Pohang University of
Science and Technology (POSTECH), San 31 Hyoja Dong, Pohang 790-784, Republic of Korea
Received November 27, 2000
Summary: A cyclic phosphorus ylide complex, (η5-
indenyl)Ru{CH2PPh2(C6H4)}(PPh3) (2), and (η5-indenyl)-
Ru(PPh3)(CO)Cl (3) were formed in the reactions of (η5-
indenyl)Ru(PPh3)2Cl (1) with CH2Cl2 and CHCl3 in the
presence of KOH and 2-propanol, respectively.
(η5-Indenyl)Ru(PPh3)2Cl (1) and related half-sandwich
ruthenium complexes have been known as versatile
catalysts in many useful transformations.1 Recently, we
have found it is an effective catalyst for the racemization
of secondary alcohols in the presence of bases,2 which
can be coupled with enzymatic acetylation for dynamic
kinetic resolution of the racemic alcohols to chiral
acetates.3 As an unexpected result from this study,
formation of a noble cyclic ruthenium phosphorus ylide
complex, (η5-indenyl)Ru{CH2PPh2(C6H4)}(PPh3) (2), was
observed when dichloromethane was used as a solvent.
This result implicates the C-Cl bond activation and led
us to the investigation for the reaction of 1 with various
haloalkanes in the presence of potassium hydroxide and
2-propanol (Scheme 1).4,5
F igu r e 1. ORTEP drawing (50% probability) of the
structure of 2 at 293 K. Selected bond distances (Å): Ru-
C(46) ) 2.170(4), Ru-C(11) ) 2.055(4), Ru-P(2) ) 2.2564-
(13), C(46)-P(1) ) 1.743(4), P(1)-C(10) ) 1.768(4), C(10)-
C(11) ) 1.403(6). Selected bond angles (deg): C(46)-Ru-
C(11) ) 85.6(2), C(46)-Ru-P(2) ) 88.36(12), C(11)-Ru-
P(2) ) 91.30(11), Ru-C(46)-P(1) ) 104.9(2), C(46)-P(1)-
C(10) ) 106.0(2), P(1)-C(10)-C(11) ) 112.3(3), C(10)-
C(11)-Ru ) 120.3(3).
Complex 2 was obtained in 95% yield by mixing a
solution of complex 1 in CH2Cl2 and a solution of KOH
in 2-propanol for 6 h at room temperature. Character-
istic peaks for diastereotopic methylene protons were
1
shown at 0.72 and 1.34 ppm in the H NMR spectrum
of 2. By a separate experiment with CD2Cl2, it was
confirmed that the source of the methylene unit is
dichloromethane. Recrystallization of 2 provided single
crystals suitable for X-ray diffraction analysis. The
molecular structure of 2 revealed the incorporation of
a methylene moiety between Ru and P and the ortho-
metalation of the triphenylphosphine ligand to form a
five-membered cyclic phosphorus ylide structure (Figure
1). The indenyl ligand is bound to the ruthenium in an
η5-fashion and shows no significant distortion. The bond
distance between the ruthenium and the ylide carbon
is 2.17 Å, which is almost the same as that found in a
linear phosphorus ylide ruthenium complex.6
To investigate the scope of the phosphorus ylide
complex forming reaction,7,8 dibromomethane, diiodo-
methane, 1,2-dichloroethane, and chloroform were sub-
jected to the reaction with 1 (Scheme 1). Simple
(1) (a) Davies, S. G.; McNally, J . P.; Smallridge, A. J . Adv. Orga-
nomet. Chem. 1990, 30, 1. (b) Consiglio, G.; Morandini, F. Chem. Rev.
1987, 87, 761. (c) Trost, B. M.; Shen, H. C. Org. Lett. 2000, 2, 2523.
(d) Simal, F.; Wlodarczak, L.; Demonceau, A.; Noels, A. F. Tetrahedron
Lett. 2000, 41, 6071. (e) Takahashi, H.; Ando, T.; Kamigaito, M.;
Sawamoto, M. Macromolecules 1999, 32, 3820. (f) Baratta, W.; Zotto,
A. D.; Rigo, P. J . Chem. Soc., Chem. Commun. 1997, 2163.
(2) Koh, J . H.; J eong, H. M.; Park, J . Tetrahedron Lett. 1998, 39,
5545.
(3) Koh, J . H.; J ung, H. M.; Kim, M.-J .; Park, J . Tetrahedron Lett.
1999, 40, 6281.
(4) For the activation of haloalkanes by metal complexes, see: (a)
Simal, F.; Wlodarczak, L.; Demonceau, A.; Noels, A. F. Tetrahedron
Lett. 2000, 41, 6071. (b) Humann-Vincent, J .; Scott, B. L.; Kubas, G.
J . Inorg. Chem. 1999, 38, 115. (c) Oliva´n, M.; Caulton, K. G. Inorg.
Chem. 1999, 38, 566. (d) Marder, T. B.; Fultz, W. C.; Calabrese, J . C.;
Harlow, R. L.; Milstein, D. J . Chem. Soc., Chem. Commun. 1987, 1543.
(e) Weinberger, B.; Tanguy, G.; Abbayes, H. D. J . Organomet. Chem.
1985, 280, C31.
(5) For related reports to show that CH2Cl2 acts as a ligand in metal
complexes, see: Huang, D.; Huffman, J . C.; Bollinger, J . C.; Eisenstein,
O.; Caulton, K. G. J . Am. Chem. Soc. 1997, 119, 7398, and references
therein.
(6) Burrell, A. K.; Clark, G. R.; Rickard, C. E. R.; Roper, W. R.;
Wright, A. H. J . Chem. Soc., Dalton Trans. 1991, 609.
(7) For a review of metal phosphorus ylide complexes, see: Schmid-
baur, H. Angew. Chem., Int. Ed. Engl. 1983, 22, 907.
(8) For examples of the formation of cyclic metal phosphorus ylide
complexes through orthometalation, see: (a) Koch, J . L.; Shapley, P.
A. Organometallics 1999, 18, 814. (b) Caballero, C.; Cha´vez, Go¨knur,
O¨ .; Lo¨chel, I.; Nuber, B.; Pfisterer, H.; Ziegler, M. L. J . Organomet.
Chem. 1989, 371, 329. (c) Clark, G. R.; Roper, W. R.; Wright, A. H. J .
Organomet. Chem. 1984, 273, C17. (d) Illingsworth, M. L.; Teagle, J .
A.; Burmeister, J . L.; Fultz, W. C.; Rheingold, A. L. Organometallics
1983, 2, 1364.
10.1021/om001003n CCC: $20.00 © 2001 American Chemical Society
Publication on Web 03/30/2001

Notes
Organometallics, Vol. 20, No. 9, 2001 1893
Sch em e 1. Rea ction s of 1 w ith Ha loa lk a n es
Sch em e 2. P r op osed P a th w a ys for th e F or m a tion of 2 a n d 3
substitution of the chloride ligand in 1 occurred in the
reactions with dibromomethane and diiodomethane to
give (η5-indenyl)Ru(PPh3)2Br and (η5-indenyl)Ru(PPh3)2I
in 55% and 82% yields,2,9 respectively, while starting
complex 1 was recovered from the reaction with 1,2-
dichloroethane. Meanwhile, (η5-indenyl)Ru(PPh3)(CO)-
Cl (3) was produced in 60% yield in the reaction with
dry chloroform. For the formation of 3, participation of
hydroxide ion was speculated, and, in fact, the yield of
3 increased up to 89% by the use of wet chloroform and
excess KOH. The spectral data of 3 were consistent with
the replacement of one phosphine ligand with CO.
Furthermore, the formation of CpRu(PPh3)(CO)Cl in the
reaction of CpRu(PPh3)2Cl under conditions similar to
that for 3 supported the replacement, which has been
synthesized from CpRu(PPh3)2Cl under CO pressure.10
In attempts to observe any intermediate for the
ture of 1 and 2 when the reaction temperature was
raised to 40 °C.
A proposal for the formation of 2 and 3 is shown in
Scheme 2. The key step for 2 would be the generation
of labile acetone complex 4 with losing one phosphine
ligand,11 from which detachment of acetone provides a
coordinatively unsaturated intermediate to activate the
C-Cl bond of dichloromethane.12 The inhibition effect
of additional PPh3 was clearly observed,13 and the
results from the experiments with (η5-indenyl)Ru-
(PPh3)2H support that the dissociation of PPh3 rather
than indenyl ring slippage would be more responsible
for generating coordinatively unsaturated intermedi-
ates. From chloromethyl intermediate 5, intramolecular
nucleophilic substitution and orthometalation followed
by deprotonation led to the formation of 2.8,14 Mean-
while, dichlorocarbene complex 6 would be a key inter-
mediate for 3,15 of which carbene carbon is attacked by
1
formation of 2 and 3 by H and 31P NMR, only starting
ruthenium complex 1 and the final products 2 and 3
were observed. A speculated intermediate, (η5-indenyl)-
Ru(PPh3)2H, was inert under conditions similar to that
for the transformation of 1 to 2. However, interestingly,
(η5-indenyl)Ru(PPh3)2H was slowly converted to a mix-
(11) Gamasa, M. P.; Gimeno, J .; Gonzalez-Bernardo, C.; Mart´ın-
Vaca, B. M.; Monti, D.; Bassetti, M. Organometallics 1996, 15, 302.
(12) The use of potassium tert-butoxide instead of 2-propanol/KOH
was not effective for the production of 2 in the reaction of 1 with
dichloromethane.
(13) Under the conditions described in the Experimental Section,
complex 2 was not formed when PPh3 (3 equiv) was added.
(14) It is also possible that complex 2 is formed via the formation of
a carbene complex from the chloromethyl intermediate. See refs 4c
and 8c.
(9) Oro, L. A.; Ciriano, M. A.; Campo, M.; Foces-Foces, C.; Cano, F.
H. J . Organomet. Chem. 1985, 289, 117.
(10) Davies, S. G.; Simpson, S. J . J . Chem. Soc., Dalton Trans. 1984,
993.

1894 Organometallics, Vol. 20, No. 9, 2001
Ta ble 1. Cr ysta llogr a p h ic Da ta for 2
Notes
formula
mol wt
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C46H38P2Ru
753.77
P1
radiation (λ, Å)
F(000)
0.71073
386
0.272
293(2)
ω
3309
3206
µ, mm-1
9.669(2)
11.245(2)
17.375(4)
102.05(3)
90.95(3)
94.60(3)
1840.5(6)
1
T, K
scan mode
no. of meads rflns
no. of indep rflns
refinement mothod
goodness of fit on F2
final R indices (I > 2σ(I))
R indices (all data)
full-matrix least-squres on F2
1.105
R1 ) 0.0272, wR2 ) 0.0620
R1 ) 0.0333, wR2 ) 0.0685
Z
d
calcd, g cm-3
0.678
123.8, 127.1 (d, J ) 2.6 Hz), 127.8 (d, J ) 8.7 Hz), 128.4 (d, J
) 7.6 Hz), 128.6 (d, J ) 7.0 Hz), 128.8, 129.8, 130.8 (dd, J )
11.0 Hz, 8.7 Hz), 132.1 (d, J ) 9.1 Hz), 132.2 (d, J ) 2.4 Hz),
132.9 (d, J ) 9.1 Hz), 134.4 (d, J ) 17.1 Hz), 134.9, 138.7 (d,
J ) 34.9 Hz), 140.2, 141.9, 145.5 (dd, J ) 14.8 Hz, 4.8 Hz),
194.7 (dd, J ) 31.1 Hz, 17.1 Hz). 31P NMR (C6D6): δ 32.9 (d,
J ) 3.2 Hz), 68.6 (d, J ) 3.2 Hz). MS (FAB, m/e): 754 (M+).
Anal. Calcd for C46H38P2Ru: C, 73.29; H, 5.08. Found: C,
72.95; H, 5.18.
X-r a y Cr ysta llogr a p h y. A suitable crystal coated with
Paratone was mounted on a Siemens SMART diffractometer
equipped with a graphite-monochromated Mo KR (λ ) 0.71073
Å) radiation source and a CCD detector. Data collection was
performed with a detector distance of 6 cm. The raw data
collected were processed to produce conventional intensity data
by the program SAINT. The intensity data were corrected for
Lorenz and polarization effects. The structure was solved by
a combination of Patterson and difference Fourier methods
provided by the program package SHELEXTL. All the non-
hydrogen atoms were refined anisotropically. Hydrogen atom
positions were calculated and included in the final cycle of
refinement. Crystallographic data of 2 are summarized in
Table 1.
hydroxide, followed by deprotonation and elimination
of chlorides to afford the carbonyl ligand.
In summary, we have found the activation of dichloro-
methane by (η5-indenyl)Ru(PPh3)2Cl in the presence of
KOH and 2-propanol to form a novel cyclic ruthenium
phosphorus ylide complex. In addition, easy ways to
prepare (η5-indenyl)Ru(PPh3)(CO)Cl and CpRu(PPh3)-
(CO)Cl have been introduced from the reactions of
chloroform with (η5-indenyl)Ru(PPh3)2Cl and CpRu-
(PPh3)2Cl, respectively.
Exp er im en ta l Section
All manipulations except workup and purification were
carried out under an atmosphere of argon using standard
Schlenk techniques. Et2O, THF, and hexane were distilled
from sodium-benzophenone ketyl. Dichloromethane and chlo-
roform were distilled from P2O5. (η5-Indenyl)Ru(PPh3)2Cl and
(η5-indenyl)Ru(PPh3)2H were prepared according to the litera-
ture procedures.9
If not otherwise stated, all NMR spectra were recorded on
a Bruker AM 300 or DPX 300. Chemical shifts are given in δ
ppm downfield from tetramethylsilane as an internal standard
and from aqueous 85% phosphoric acid solution (δ 0, 31P) as
an external standard. IR spectra were taken for the thin films
of samples on NaCl plates. Mass spectral analysis was
recorded on a J EOL J MS-AM505WA and is reported in units
of mass to charge (m/e). Melting points were measured on a
Thomas-Hoover capillary melting point apparatus and are
uncorrected. Elemental analyses were performed by the Center
for Biofunctional Molecules at Pohang University of Science
and Technology.
(η5-In d en yl)Ru (P P h 3)(CO)Cl (3). To a solution of 1 (30
mg, 0.040 mmol) in degassed and wet CHCl3 (3.0 mL) was
added a solution of KOH (32 mg, 0.57 mmol) solution in
2-propanol (0.3 mL). After being stirred for 40 h at 30 °C, the
reaction mixture was concentrated, and the residue was
chromatographed to give 19.3 mg (89%) of yellow solid 3, which
was then recrystallized from a mixture of THF and hexane.
1
Mp: 211 °C (dec). H NMR (C6D6): δ 3.72 (s, 1H), 5.03 (t, J )
2.54 Hz), 5.45 (s, 1H), 6.59-7.60 (m, 18H). 13C NMR (C6D6):
δ 67.6, 73.8 (d, J ) 43.5 Hz), 90.9, 114.5, 115.2, 123.1, 126.1,
128.7, 129.0, 129.1, 130.6, 134.4, 134.5, 134.9, 205.2 (d, J )
89.4 Hz). 31P NMR (C6D6): δ 48.88 (s). IR (NaCl, cm-1): ν-
(η5-In d en yl)Ru {CH2P P h 2(C6H4)}(P P h 3) (2). To a solution
of 1 (82 mg, 0.10 mmol) in CH2Cl2 (2.0 mL) was added a
solution of KOH (30 mg, 0.50 mmol) in 2-propanol (0.80 mL,
10 mmol). After being stirred for 6 h at room temperature,
the reaction mixture was concentrated, and the residue was
chromatographed to give 72 mg (95%) of orange solid 2, which
was then recrystallized from a mixture of Et2O and hexane.
(CO) 1944 (s). MS (FAB, m/e): 542 (M+). Anal. Calcd for C28H22
-
ClOPRu: C, 61.99; H, 4.20. Found: C, 61.46; H, 3.96.
Ack n ow led gm en t. We are grateful for the financial
support by Polymer Research Institute and KOSEF
through the Center of Integrated Molecular System.
1
Mp: 185 °C (dec). H NMR (C6D6): δ 0.72 (ddd, J ) 12.4 Hz,
9.7 Hz, 8.3 Hz, 1H), 1.34 (dd, J ) 12.1 Hz, 12.1 Hz, 1H), 3.85
(s, 1H), 5.06 (t, J ) 2.5 Hz, 1H), 5.14 (s, 1H), 6.62-7.14 (m, 30
H), 7.56 (m, 2H), 8.00 (m, 1H). 13C NMR (C6D6): δ -10.0 (dd,
J ) 25.5 Hz, 7.9 Hz), 64.4 (d, J ) 13.3 Hz), 68.4, 92.4, 106.6,
107.7, 119.5 (d, J ) 12.6 Hz), 122.0 (d, J ) 3.4 Hz), 122.4,
Su p p or tin g In for m a tion Ava ila ble: Structural diagrams
with full atom labeling and tables of bond distances, angles,
anisotropic parameters, and atomic coordinates for 2. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(15) For examples of using chloroform and KOH for in situ genera-
tion of metal carbonyl complexes, see: Grushin, V. V.; Alper, H.
Organometallics 1993, 12, 3846, and references therein.
OM001003N