Conformationally rigid diphosphine arene-ruthenium(II) complexes as catalysts for transfer hydrogenation of ketones

Article abstract of DOI:10.1016/S0022-328X(02)02216-7

Conformationally rigid [(η⁶-arene)Ru (P-P)Cl]CF₃SO₃ (arene=C₆H₆ (1), p-MeC₆H₅CHMe₂ (2), 1,3,5-Me₃C₆H₃ (3), and Me₆C₆ (4); P-P is 2-diphenylphosphino-5, 6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene) compounds have been synthesized from [(η⁶-arene)RuCl₂(DMPP)] (DMPP=3,4-dimethyl-1-phenylphosphole) and diphenylvinylphosphine (DPVP) in the presence of AgCF3_SO₃. The structures of 2, 3 and 4 were determined by X-ray crystallography. These complexes have been found to be quite effective catalysts for the transfer hydrogenation of ketones in 2-propanol in the presence of KOH.

Full text of DOI:10.1016/S0022-328X(02)02216-7

Journal of Organometallic Chemistry 669 (2003) 48Á56
/
www.elsevier.com/locate/jorganchem
Conformationally rigid diphosphine areneÁ
/
ruthenium(II) complexes
as catalysts for transfer hydrogenation of ketones
Kesete Y. Ghebreyessus, John H. Nelson *
Department of Chemistry/216, University of Nevada-Reno, Reno, NV 89557-0020, USA
Received 8 November 2002; received in revised form 17 December 2002; accepted 17 December 2002
Abstract
Conformationally rigid [(h6-arene)Ru(PÃ
(4); PÃP is 2-diphenylphosphino-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene) compounds have been synthesized from
[(h6-arene)RuCl2(DMPP)] (DMPPꢀ
3,4-dimethyl-1-phenylphosphole) and diphenylvinylphosphine (DPVP) in the presence of
/
P)Cl]CF3SO3 (areneꢀ/C6H6 (1), p-MeC6H5CHMe2 (2), 1,3,5-Me3C6H3 (3), and Me6C6
/
/
AgCF3SO3. The structures of 2, 3 and 4 were determined by X-ray crystallography. These complexes have been found to be quite
effective catalysts for the transfer hydrogenation of ketones in 2-propanol in the presence of KOH.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Phosphole; Vinylphosphine; [4ꢁ
/
2]DielsÁAlder cycloaddition; Ruthenium; Transfer hydrogenation
/
1. Introduction
tem reported by Noyori et al., is among the more
recently developed and efficient catalysts [4aÁe]. Besides
electronic effects, rigid or restrained ligands have been
identified to be of pivotal importance [5aÁe]. Recently,
we have reported the synthesis and characterization of a
variety of [(h6-arene)Ru(PÃ
P)Cl]PF6 (where PÃP is 2-
diphenylphosphino-5,6-dimethyl-7-phenyl-7-phosphabi-
cyclo[2.2.1]hept-5-ene) complexes and have succeeded in
the isolation of their diastereomerically pure forms [6].
However, the use of these complexes with the PF6ꢂ
counter ion as catalysts may not be judicious, because
the PF6ꢂ anion is prone to base promoted hydrolysis
under the reaction conditions used during the catalytic
process. To avoid this complication and as part of a
study aimed at expanding the synthetic utility of these
/
Transition-metal catalyzed transfer hydrogenation
using 2-propanol as a hydrogen source has become an
efficient method in organic synthesis as illustrated by
several useful applications reported in recent years
[1a,1b]. The reaction conditions for this important
process are economic, relatively mild and environmen-
tally friendly. The most commonly used catalysts for
this reaction are ruthenium(II) complexes, but some
rhodium, iridium and samarium derivatives have also
/
/
/
been used [2aÁ
m(II) complexes of the type [(h6-arene)Ru(AÃ
B is an optically pure chiral
/
g]. In particular, half-sandwich rutheniu-
/
B)X]ꢁXꢂ (where AÃ
/
bidentate ligand and X is a halide have been found to
be efficient catalyst precursors for these reactions [3].
Specifically, the (h6-arene)Ru(TsDPEN)Cl (TsDPENꢀ
N-(p-tolylsulponyl)-1,2-diphenylethylenediamine) sys-
areneÁ
synthesis of conformationally rigid [(h6-arene)-
Ru(II)(PÃP)Cl]CF3SO3 (areneꢀC6H6 (1), p-MeC6H5-
/ruthenium(II) complexes, herein, we report the
/
/
/
CHMe2 (2), 1,3,5-Me3C6H3 (3), and Me6C6 (4)) com-
plexes (with triflate as a counter ion) and their applica-
tion for the transfer hydrogenation of ketones. The
* Corresponding author. Tel.: ꢁ
6804.
E-mail address: jhnelson@equinox.unr.edu (J.H. Nelson).
/
1-775-784-6588; fax: ꢁ1-775-784-
/
highly efficient and diastereoselective [4ꢁ
/
2] DielsÁ
/
Alder cyclo-addition methodology was employed for
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(02)02216-7

K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á
/56
49
the synthesis of these complexes [7aÁ
plexes are easily prepared and are air and moisture
stable crystalline materials.
/
g]. These com-
figuration of the C(1) and C(4) stereocenters are fixed
relative to P(7) and only those at the C(2) (the ring
conjunction carbon) and P(7) may vary. For these
complexes the stereochemistry of C(2) is the same as
that of P(7). Thus, for ease of discussion, we will refer to
the absolute configuration of the chiral ligand by a
single descriptor R or S. Ruthenium becomes a stereo-
center in the products and may have either R or S
absolute configuration leading to racemic diastereomers
A (RRuRP7RC2/SRuSP7SC2) and B (RRuSP7SC2/SRuRP7-
RC2). Crystallization of the diastereomeric mixtures
2. Results and discussion
2.1. Synthesis and characterization of 1Á4
/
The complexes were prepared by treating a dichlor-
omethane solution of [(h6-arene)Ru(DMPP)Cl2] (arene
ꢀC6H6 (1), p-MeC6H5CHMe2 (2), 1,3,5-Me3C6H3 (3),
/
from nitromethaneÁether solution afforded orange
/
and Me6C6 (4)) with one equivalent of diphenylvinyl-
phosphine (DPVP) in the presence of AgCF3SO3
(Scheme 1).
After addition of the DPVP the reaction mixtures
were stirred for 72 h at ambient temperature in the dark.
crystals which correspond to the major diastereomers
as confirmed by X-ray crystallography and 31P{1H}-
NMR spectroscopy. The structures of 2, 3 and 4 were
determined by X-ray crystallography. In all the three
structures, the geometry around the ruthenium center is
pseudo-octahedral with the h6-arene, the asymmetric
bidentate phosphine and the chloride atom completing
the coordination sphere. Views of the cations are given
Upon workup the products were isolated as orangeÁ
/
yellow air and moisture stable powders. Preliminary,
31P{1H}-NMR analysis of the crude reaction mixture
suggested the presence of two diastereomers in the
in Figs. 1Á3. Crystallographic data are summarized in
/
ratios: 1a:1bꢀ
/
1:100, 2a:2b 1:9, 3a:3bꢀ1:100 and
/
Table 1 and selected bond lengths and angles are
presented in Table 2. Although the complexed aromatic
rings in 2, 3 and 4 are almost planar, there is a
4a:4b 1:19. These two racemic diastereomers illustrated
below, and for simplicity designated as A and B,
respectively, may be distinguished by 31P{1H}-NMR
spectroscopy. In general [6] the chemical shift difference
significant variation in the RuÃ
/
C (arene) bond dis-
tances. As can be seen from Table 2 the Ru(1)Ã
/C(1)
of the phosphorus resonances, Ddꢀ
/
dP7ꢂdP2 is greater
/
˚
˚
(2.340(5) A), Ru(1)Ã
/
C(2) (2.296(6) A) and Ru(1)Ã
/C(4)
for diastereomer A than for diastereomer B (vide infra).
On this basis, we conclude that the major diastereomer
is B in each case, the thermodynamically more stable
diastereomer as was also found for the PF6ꢂ analogs [6].
˚
(2.304(5) A) bond distances for 2 are significantly longer
˚
than the Ru(1)Ã
/
C(5) (2.205(5) A) and Ru(1)Ã
/
C(6)
C(3)
C(5)
˚
(2.224(5) A) bond distances. Similarly the Ru(1)Ã
/
˚
˚
(2.299(8) A), Ru(1)Ã
/
C(4) (2.298(8) A) and Ru(1)Ã
/
˚
(2.313(7) A) bond distances for 3 are significantly longer
˚
than the Ru(1)Ã
/
C(1) (2.236(7) A) and Ru(1)Ã
/
C(6)
˚
(2.224(7) A) bond distances. And, for 4 the Ru(1)Ã
/
˚
˚
C(3) (2.336(8) A), Ru(1)Ã
/
C(4) (2.321(8) A), Ru(1)Ã
/
˚
˚
C(6) (2.329(7) A) bond
C(5) (2.310(7) A) and Ru(1)Ã
/
Because the [4ꢁ
/
2] DielsÁ/Alder cycloadditions all
occur intramolecularly [7aÁ/f] within the ruthenium
coordination sphere to form the syn-exo-7-phosphanor-
bornene skeleton (illustrated above) the absolute con-
Fig. 1. Structural drawing of the cation of 2 showing the atom
numbering scheme (20% probability thermal ellipsoids). Hydrogen
atoms are omitted for clarity.
Scheme 1.

50
K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á56
/
ing alcohols via hydrogen transfer from 2-propanol with
KOH as the promoter. As the starting point, the
performance of the catalysts in the transfer hydrogena-
tion was screened by using acetophenone as a model
substrate (Eq. (1)).
ð1Þ
In a typical experiment the preformed, isolated
crystalline catalyst (0.05 mmol) was dissolved by heating
in 2-propanol for 15 min. After the catalysts had
completely dissolved, acetophenone (10.0 mmol) and a
solution of KOH (0.25 mmol) in 2-propanol were
successively added and the reaction was performed at
82 8C. The reactions were conducted at a substrate/
catalyst/base (S/C/base) molar ratio of 200:1:5. Under
the reaction conditions complex 3 proved to be most
effective catalyst relative to 1, 2 and 4. For instance the
observed turnover frequency (TOF) measured during
the first 10 min for 3 is 1004 per h whereas those of 1, 2
and 4 are 115, 308 and 571 hꢂ1, respectively. The
reduction of acetophenone with 3 was completed within
1/2 h in 98% isolated yield. In contrast, acetophenone
Fig. 2. Structural drawing of the cation of 3 showing the atom
numbering scheme (20% probability thermal ellipsoids). Hydrogen
atoms are omitted for clarity.
was reduced within 3Á5 h using 1, 2, and 4 in 95, 93 and
/
95% isolated yield, respectively. The progress of the
transfer hydrogenation of acetophenone using 3 as a
catalyst is shown in Fig. 4.
As the cationic Ru(II) complex 3 appeared to be the
most active precursor for the transfer hydrogenation,
the reduction of ketones other than acetophenone was
attempted in the presence of 3. A variety of ketones (S/
C/base molar ratio 200:1:5) were transformed to the
corresponding secondary alcohols. Typical results are
shown in Table 3. The catalyst performed similarly with
m-methoxy acetophenone. However, the reduction of p-
methoxy acetophenone tends to proceed at significantly
lower rate and yield. Complex 3 also catalyzed the
transfer hydrogenation of 1- or 2-acetonaphthone very
effectively but at different rates (Table 3, entries 5 and
6). Moreover, complex 3 shows good activity in the
transfer hydrogenation of both five- and six-membered
cyclic ketones (Table 3, entries 7 and 8). Interestingly, 3
also catalyzed the reduction of methyl isobutyl ketone
(Table 3, entry 9). In most cases, the conversions to the
respective alcohols were essentially quantitative and
comparable to those found for acetophenone. The
reaction proceeds even at a lower catalyst loading (S/
C/base ratio 1000:1:5) although at a lower rate (required
4 h reaction time with 3). The influence of different
inorganic bases on the catalytic activity was also
investigated. Addition of bases like KOH, NaOH or
Na-(iOPr) leads to similar final conversion, but the
highest rate was observed when KOH was employed. In
contrast to what is observed for Noyori’s [4e] catalysts,
Fig. 3. Structural drawing of the cation of 4 showing the atom
numbering scheme (30% probability thermal ellipsoids). Hydrogen
atoms are omitted for clarity.
distances are significantly longer than the Ru(1)Ã
/
C(1)
C(2) (2.280(8) A) bond dis-
˚
˚
(2.262(7) A) and Ru(1)Ã
/
tances. These distortions probably arise from the steric
constraints imposed by the asymmetric bidentate phos-
hine and the trans influence of the phosphorus ligands
[8]. These bond length data indicate that the complexes
could easily slide across the face of the arene to reach the
h4-coordination mode (during the catalytic process) and
hence provide access to a vacant coordination site on the
metal [9aÁ
c]. As expected, their 1H-, 13C{1H}-, and
/
31P{1H}-NMR spectra are consistent with those re-
ported for the analogous complexes with the PF6ꢂ
counter ion [6].
2.2. Catalytic transfer hydrogenation of ketones
The conformationally rigid ruthenium(II) complexes
1Á4 catalyze the reduction of ketones to the correspond-
/

K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á
/56
51
Table 1
Crystallographic data and structure refinement for 2, 3 and 4
Compound
Formula
Mw
2
3
4
C
881.25
38H43ClF3O3P2RuS
C36H38ClF3O3P2RuS
806.18
Triclinic
C39H44ClF3O3P2RuS
848.26
Triclinic
Crystal system
Space group
Triclinic
¯
¯
¯
1
P
/1/
P
/
1
/
P/ /
˚
a (A)
11.4694(14)
12.3129(18)
15.6882(10)
2
11.177(3)
11.412(3)
14.943(3)
2
11.233(3)
11.3207(19)
16.010(2)
2
˚
b (A)
˚
c (A)
Z
a (8)
b (8)
g (8)
Volume (A )
rcalc (g cmꢂ3
Reflections collected
96.943(9)
105.962(8)
107.839(12)
1976.1(4)
1.481
84.112(15)
86.446(18)
72.76(2)
1809.8(7)
1.479
92.906(14)
93.934(14)
104.874(17)
1958.2(7)
1.439
3
˚
)
7917
6881
7501
6352
7913
6804
Independent reflections
a
R1
0.0566
0.1598
1.057
0.0681
0.1470
1.044
0.0709
0.1677
1.026
b
wR2
Goodness-of-fit
a
The data were refined by the method of full-matrix least-squares on F2, with the final R indices having I ꢀ
/
2.00s(I), R1ꢀ
/
ajjFojꢂjFcjj/aFo.
/
wR2(F2)ꢀ
/
{a[w(F2oꢂ
/
F2c)]/a[w(Fo2)2]}1/2
.
b
Table 2
˚
Selected bond distances (A) and bond angles (8) for 2, 3 and 4
2
3
4
Bond distances
RuÃ
RuÃ
RuÃ
RuÃ
RuÃ
RuÃ
RuÃ
RuÃ
RuÃ
/
P(1)
P(2)
Cl
2.3004(4)
2.3310(13)
2.3925(13)
2.340(5)
2.296(6)
2.274(5)
2.304(5)
2.205(5)
2.224(5)
2.308(2)
2.324(2)
2.401(2)
2.236(7)
2.259(7)
2.299(8)
2.298(8)
2.313(7)
2.224(7)
2.293(2)
2.3395(19)
2.405(2)
2.262(7)
2.280(8)
2.336(8)
2.321(8)
2.310(8)
2.329(7)
/
/
/
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
/
/
/
/
/
Bond angles
P(1)Ã
P(2)Ã
P(1)Ã
/
RuÃ
RuÃ
RuÃ
/
Cl
87.34(5)
91.34(5)
79.94(5)
86.99(8)
91.42(7)
79.82(7)
87.05(7)
90.54(7)
79.29(7)
Fig. 4. Time course of the transfer hydrogenation of acetophenone
using 0.5 mol% of 3 as a catalyst in 2-propanol.
/
/Cl
/
/P(2)
reaction time are (5:6:7:8) 2.7:1.8:1.7:1, respectively.
These results indicate that the reduction of the activated
in the absence of a base no transfer hydrogenation of the
ketones was observed. This suggests that a different
mechanism operates than the concerted proton-transfer
proposed for many Ru(aminoalcohol) systems [10].
Furthermore, the catalysts were inactive with the formic
double bond is preferred to CÄ
/
O reduction which is in
agreement with the general trends seen with other
hydrogen transfer catalysts [11].
In contrast to what is observed for most other
catalysts, a significant advantage of these catalysts is
their insensitivity toward air and moisture. In this way
rigorous pretreatment of solvents and substrates is
avoided. Thus, reaction mixtures can be loaded into
the reaction vessel in the open air and monitoring of the
reaction progress also becomes very convenient.
Furthermore, the ease by which these catalysts are
prepared offers another important advantage.
acidÁ
The a, b-unsaturated ketone substrates are reduced
/
/triethylamine azeotrope [4d] as a hydrogen source.
both at the CÄ
/
O bond and the CÄ
/
C moiety; with the CÄ
C bond being more easily reduced. Initial analysis
revealed that ketones resulting from the reduction of
the CÄ
formed are unsaturated and saturated alcohols resulting
from the reduction of the CÄO of the starting substrates
/C were the major products. Other products
/
or the subsequent reduction of the saturated ketone
produced during the catalytic process (Scheme 2). The
ratios of the starting ketone and the products after 48 h
As to the mechanism, we postulate that the active
species in the reduction is a ruthenium(II) monohydride
(Scheme 3). Pa´mies and Backvall [12] studied the
¨

52
K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á56
/
Table 3
Hydrogenation of ketones in 2-propanol catalyzed by diphosphine Ru(II) Complexa
3
aReaction conditions: 0.2 M substrate solution, molar ratio S/C/base 200:1:5 and 82 8C temperature.
bIsolated yield and the bracket product yield determined by GC.
cProduct yield determined by 1H-NMR.
dProduct yield determined by GC.
eTurnover frequency: moles of product per mole of catalyst per hour, in hꢂ1 measured during the first 10 and
f30 min, respectively.
mechanism for a number of bisphosphineruthenium(II)
complexes by monitoring the racemization of mono-
deuterated S-phenylethyl alcohol with acetophenone
and found that the catalysts under study in most of
the cases followed the monohydride pathway.
involving a concerted addition of a proton and hydride
via a six-membered transition state. In our system, this
special case of the concerted hydride and proton transfer
can be excluded, since we do not have a pendant proton
carrier group (e.g. NH) in our bidentate ligand. It is
conceivable that a vacant coordination site on ruthe-
nium could also arise from dissociation of one end of the
diphosphine ligand. Since this diphosphine ligand is
both a very good ligand and conformationally rigid we
believe that the proposed ring slippage is more likely.
Since our catalysts are similar to those studied by
Pa´mies and Backvall we assume that they follow the
¨
monohydride pathway. More recently, Noyori et al. [13]
revealed that the Ru(II) catalyzed transfer hydrogena-
tion in 2-propanol proceeded by a hydride route

K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á
/56
53
preparing optically pure forms of complexes 1Á
/
4 so that
we may probe enantiomeric excesses in these reactions.
4. Experimental
4.1. Reagents and physical measurements
All chemicals were reagent grade and were used as
received or synthesized as described below. DMPP, [14]
DPVP, [15] 1,3,5-trimethylcyclohexa-1,4-diene, [16] [(h6-
arene)RuCl2]2, [17] and [(h6-arene)Ru(DMPP)Cl2] [18]
were synthesized by literature procedures. Elemental
analysis were performed by Galbraith Laboratories,
Knoxville, TN. Melting points were obtained using a
Mel-Temp apparatus and are uncorrected. NMR spec-
tra were recorded on a Varian Unity Plus-500 FT-NMR
Scheme 2.
3. Concluding remarks
We have demonstrated that the racemic complex 3 is
easily prepared and isolated in a diastereomerically pure
form. It is an excellent catalyst for the transfer hydro-
genation of a variety of ketones. We are at present
1
spectrometer operating at 500 MHz for H, 125.7 MHz
for 13C and 202.3 MHz for 31P. Proton and carbon
Scheme 3. Proposed schematic catalytic cycle for the transfer hydrogenation of ketones catalyzed by [(h6-arene)Ru(PÃ
monohydride species.
/
P)Cl]ꢁ involving a

54
K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á56
/
chemical shifts are relative to internal Me4Si, while
phosphorus chemical shifts are relative to external 85%
H3PO4 (aq) with positive values being downfield of the
respective reference. Gas chromatographic measure-
ments were made isothermally at 215 8C on a GOW-
MAC series 150 or at 280 8C on a Hewlett-Packard
4J(PC)ꢀ
4J(PC)ꢀ
/
2.3 Hz, Cp), 131.34 (dd, 2J(PC)ꢀ
/
17.0 Hz,
4
/
1.3 Hz, C6), 131.04 (d, J(PC)ꢀ
/
2.8 Hz, Cp),
2
2
130.98 (d, J(PC)ꢀ
9.2 Hz, Co), 129. 17 (d, J(PC)ꢀ
(bd, 3J(PC)ꢀ8.8 Hz, Cm), 128.74 (d, 3J(PC)ꢀ
Cm), 128.25 (d, 1J(PC)ꢀ
51.8 Hz, Ci), 121.07 (q,
1J(CF)ꢀ
320.9 Hz, CF3), 95.63 (t, J(PC)ꢀ2.3 Hz, C,
arene), 57.45 (dd, J(PC)ꢀ
/
9.2 Hz, Co), 130.92 (bd, J(PC)ꢀ
/
3
/
10.1 Hz, Cm), 129.10
/
/
10.9 Hz,
/
HP5890 GCÁ
/
MS instrument, 20% DC200 on Chromo-
sorb P (10.16, 0.64 cm) or HP-1 (cross linked methyl
/
/
1
2
/
37.6 Hz, J(PC)ꢀ
/12.7 Hz,
1
3
siloxane) columns (2.5 m, 0.11 mm) were used.
C1), 47.66 (dd, J(PC)ꢀ
/
33.4 Hz, J(PC)ꢀ
/1.6 Hz, C4),
31.09 (dd, 1J(PC)ꢀ39.2 Hz, 2J(PC)ꢀ
/
/
30.8 Hz, C2),
2
2
30.23 (dd, J(PC)ꢀ
(appt, 3J(PC)ꢀ4
J(PC)ꢀ
3J(PC)ꢀ
3.4 Hz, CH3).
31P{1H}-NMR (202.329 MHz, CD3NO2, 25 8C).
d 141.99 (d, 2J(PP)ꢀ
58.1 Hz, 1P, P7), 59.51 (d,
2J(PP)ꢀ
58.1 Hz, 1P, P2).
Compound 2: m.p. 201Á
/
9.2 Hz, J(PC)ꢀ
/
2.1 Hz, C3), 13.89
4.2. General procedure for the synthesis of the complexes
/
/2.1 Hz, CH3), 12.35 (d,
/
The complexes were all synthesized by the following
general procedure. To a solution containing 0.5 mmol of
the [(h6-arene)Ru(DMPP)Cl2] complex in 40 ml CH2Cl2
was added 0.5 mmol of solid AgCF3SO3 in the dark.
The reaction mixture was purged with nitrogen for 15
min. Then 0.6 mmol of diphenylvinylphosphine (DPVP)
was added via syringe. After the addition of the DPVP
the solution was stirred for 72 h under nitrogen at
ambient temperature. The red color of the solution
gradually became orange during the progress of the
reaction. The solution was filtered through celite to
remove AgCl. The volume of the filtrate was reduced to
ca. 5 ml by rotary evaporation and ether was added to
/
/
/
203 8C (72% yield); Anal.
Calc. for C37H40ClF3O3P2RuS: C, 54.18; H, 4.92.
Found: C, 53.96; H, 5.08%.
1H-NMR (499.827 MHz, CD3NO2, 25 8C)
d 7.93 (m, 2H, Ho), 7.79 (m, 2H, Ho), 7.66 (m, 2H,
3
Hp), 7.56 (m, 9H, Ho,m,p), 5.91 (dd, J(HH)ꢀ
/
6.5 Hz,
6.5
6.5 Hz, 1H, CH,
6.5 Hz, CH, arene), 3.87 (app
J(H1H)ꢀ2
J(PH)ꢀ2.0 Hz, 1H, H1),
3.56 (dddd, 3J(PH)ꢀ41.5 Hz,, 3J(H2H4)ꢀ
9.5 Hz,
2J(PH)ꢀ5.5 Hz,, 3J(H1H2)ꢀ2.0 Hz, 3J(H2H3)ꢀ
0.5
Hz,1H, H2), 3.19 (dd, J(H3H5)ꢀ4.0 Hz, J(H1H5)ꢀ
2.0 Hz, 1H, H5), 2.40 (dddd, 3J(PH)ꢀ
23.5 Hz,
2J(H3H4)ꢀ13.3 Hz, 3J(H3H5)ꢀ4.0 Hz, 3J(H2H3)ꢀ
0.5 Hz, 1H, H3), 2.10 (septet, 3J(HH)ꢀ
7.0 Hz, 1H,
CH), 1.94 (s, 3H, CH3), 1.71 9 (s, 3H, CH3), 1.49 (s, 3H,
CH3), 1.09 (d, 3J(HH)ꢀ
7.0 Hz, 3H, CH3), 0.93 (d,
3J(HH)ꢀ
7.0 Hz, 3H, CH3).
13C{1H}-NMR (125.691 MHz, CD3NO2, 25 8C).
3
J(PH)ꢀ
/
1.0 Hz, 1H, CH, arene), 5.62 (d, J)HH)ꢀ
/
Hz, 1H, CH, arene), 5.45 (d, 3J(HH)ꢀ
/
3
arene), 5.22 (d, J(HH)ꢀ
/
q, 4J(H1H5)ꢀ3
/
/
/
precipitate the products. The resulting orangeÁyellow
/
/
/
precipitates were isolated by filtration, washed with
ether and dried under vacuum at ambient temperature.
/
/
/
4
4
/
/
/
/
/
/
/
/
/
Compound 1: m.p. 258Á260 8C (59% yield); Anal.
/
2
3
Calc. for C33H32ClF3O3P2RuS: C, 51.87; H, 4.22.
d 139.05 (dd, J(PC)ꢀ
/
2.6 Hz, J(PC)ꢀ1.3 Hz, C6),
/
Found: C, 51.54; H, 4.38%.
134.80 (d, 1J(PC)ꢀ44.5 Hz, Ci), 134.53 (d, 2J(PC)ꢀ
/
/9.8
1H-NMR (499.827 MHz, CD3NO2, 25 8C).
d 7.99 (m, 2H, Ho), 7.83 (m, 2H, Ho), 7.63 (m, 6H,
Hm), 7.52 (m, 5H, Ho, p), 5.65 (s, 6H, CH, arene), 3.94
Hz, Co), 131.99 (d, J(PC)ꢀ
1J(PC)ꢀ41.2 Hz, 3J(PC)ꢀ
4J(PC)ꢀ
131.31 (d, 3J(PC)ꢀ
Hz, Co), 131.00 (dd, 2J(PC)ꢀ
C5), 129.41 (d, 1J(PC)ꢀ
49.5 Hz, Ci), 129.25 (d,
3J(PC)ꢀ10.1 Hz, Cm), 128.63 (d, 3J(PC)ꢀ
Cm), 121.06 (q, J(PC)ꢀ
arene), 106.59 (d, J(PC)ꢀ
J(PC)ꢀ3.0,1.6 Hz, C, arene), 95.57 (dd, J(PC)ꢀ
Hz, C, arene), 94.99 (dd, J(PC)ꢀ4.4, 2.5 Hz, C, arene),
91.60 (d, J(PC)ꢀ
4.9 Hz, C,arene), 57.45 (dd, 1J(PC)ꢀ
36.6 Hz, 2J(PC)ꢀ12.6 Hz, C1), 48.71 (dd, 1J(PC)ꢀ
33.4
/2.6 Hz, Cp), 131.70 (dd,
4
/
/
1.6 Hz, Ci), 131.42 (d,
4
/
2.3 Hz, Cp), 131.36 (d, J(PC)ꢀ
2.3 Hz, Cm), 131.03 (d, 2J(PC)ꢀ
15.6 Hz, 4J(PC)ꢀ
1.1 Hz,
/2.5 Hz, C1),
3
2
(appt td, J(H1H2)ꢀ4
/
J(H1H5)ꢀ
/
2.0 Hz, J(PH)ꢀ
/
1.5
/
/8.0
Hz, 1H, H1), 3.53 (appt ddtt, 3J(PH)ꢀ
/42.5 Hz,
/
/
2J(PH)ꢀ
Hz, 3J(H1H2)ꢀ
2J(PH)ꢀ3.5 Hz, 4J(H1H5)ꢀ3
H5), 2.39 (dddd, 3J(PH)ꢀ23.5 Hz, 2J(H3H4)ꢀ
3J(H2H3)ꢀ3.0 Hz, 3J(H3H5)ꢀ
1.5 Hz, 1H, H3), 1.88 (s,
3H, CH3), 1.73 (dddd, 3J(PH)ꢀ
/
10.0 Hz, J(H2H4)ꢀ
1.5 Hz, 1H, H2), 3.27 (appt dt,
J(H3H5)ꢀ1.5 Hz, 1H,
13.0 Hz,
/
8.5 Hz, J(H2H3)ꢀ
/
3.0
/
3
3
/
/
/
10.8 Hz,
1
/
/
/
/320.8 Hz, CF3), 118.63 (s, C,
/
/
/1.3 Hz, C, arene), 98.20 (dd,
/
/
/
/
2.8,1.6
/
24.5 Hz, 3J(PH)ꢀ
13.0 Hz, J(H2H4)ꢀ
1.54 (s, 3H, CH3).
13C{1H}-NMR (125.692 MHz, CD3NO2, 25 8C).
/
20.5
/
2
3
Hz, J(H3H4)ꢀ
/
/
8.5 Hz, 1H, H4),
/
/
/
/
3
1
Hz, J(PC)ꢀ
2J(PC)ꢀ30.3 Hz, C2), 30.43 (dd, 2J(PC)ꢀ
2J(PC)ꢀ
(s, CH3), 17.76 (s, CH3),13.89 (appt, 3J(PC)ꢀ4
/
1.5 Hz, C4), 31.25 (dd, J(PC)ꢀ
/39.6 Hz,
2
4
d 138.97 (dd, J(PC)ꢀ
135.09 (d, 1J(PC)ꢀ
Hz, Co), 131.92 (dd, 1J(PC)ꢀ
Ci), 131.57 (d, 4J(PC)ꢀ
2.4 Hz, Cp), 131.46 (d,
/
2.8 Hz, J(PC)ꢀ
/
1.5 Hz, C5),
/
/
10.9 Hz,
/
46.0 Hz, Ci), 134.78 (d, 2J(PC)ꢀ
/
9.9
/
2.3 Hz, C3), 29.82 (s, CH), 21.20 (s, CH), 20.64
J(PC)ꢀ
3.5 Hz, CH3).
/
43.1 Hz, 3J(PC)ꢀ
/1.4 Hz,
/
/
3
/
1.6 Hz, CH3), 12.31 (d, J(PC)ꢀ
/

K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á
/56
55
31P{1H}-NMR (202.329 MHz, CD3NO2, 25 8C).
13C{1H}-NMR (125.691 MHz, CD3NO2, 25 8C).
2
2
Major: d 142.07 (d, J(PP)ꢀ
/
56.4 Hz, 1P, P7), 58.38
d 140.20 (s, Co), 134.05 (d, J(PC)ꢀ
/
41.6 Hz, Ci),
(d, 2J(PP)ꢀ
2J(PP)ꢀ
51.3 Hz, 1P, P7), 46.30 (d, J(PP)ꢀ
1P, P2).
Compound 3: m.p. 250Á
/
56.4 Hz, 1P, P2); Minor: 140.20 (d,
132.77 (bs, Co), 132.65 (d, 2J(PC)ꢀ
/
12.4 Hz, Co), 131.52
2
4
4
/
/51.3 Hz,
(d, J(PC)ꢀ
Cp), 131.20 (d, 3J(PC)ꢀ
2J(PC)ꢀ15.6 Hz, C6), 129.62 (d, 2J(PC)ꢀ
Ci), 129.13 (d, 3J(PC)ꢀ
10.9 Hz, Cm), 129.01 (d,
3J(PC)ꢀ
9.6 Hz, Cm), 128.89 (bs, Cp), 128.60 (d,
4J(PC)ꢀ
123.60 (q, 1J(CF)ꢀ
J(PC)ꢀ
2.0, Hz, C arene), 58.19 (dd, 1J(PC)ꢀ
Hz, 2J(PC)ꢀ12.9 Hz, C1), 50.12 (dd, 1J(PC)ꢀ
35.6 Hz,
3J(PC)ꢀ1.4 Hz, C4), 34.26 (dd, 1J(PC)ꢀ
40.0 Hz,
2J(PC)ꢀ29.2 Hz, C2), 31.17 (dd, 2J(PC)ꢀ
9.7 Hz,
2J(PC)ꢀ
1.1 Hz, C3), 14.64 (s, CH3, arene), 13.95
(appt, 3J(PC)ꢀ4
J(PC)ꢀ1.7 Hz, CH3), 12.21 (d,
3.3 Hz, CH3).
/
3.6 Hz, Cp), 131.243 (d, J(PC)ꢀ
8.2 Hz, Cm), 130.74 (d,
50.9 Hz,
/
2.6 Hz,
/
/
252 8C (62% yield); Anal.
/
/
Calc. for C36H38ClF3O3P2RuS: C, 51.63; H, 4.75;
/
Found: C, 51.45; H, 4.62%.
1H-NMR (499.827 MHz, CD3NO2, 25 8C).
d 7.95 (m, 2H, Ho), 7.79 (bs, 2H, Ho), 7.68 (m, 6H,
/
2
/
1.2 Hz, Cp), 128.49 (d, J(PC)ꢀ
320.8 Hz, CF3), 106.32 (appt,
33.8
/8.0 Hz, Co),
/
H
m,p), 7.55 (m,3H, Hm,p), 7.36 (m, 2H, Ho), 5.91 (dd,
3J(HH)ꢀ
6.5 Hz, J(PH)ꢀ1.0 Hz, 1H, CH, arene), 5.62
(d, J)HH)ꢀ6.5 Hz, 1H, CH, arene), 5.12 (s, 3H, CH,
arene), 3.87 (app t, J(H1H2)ꢀ4
H1), 3.35 (dddd, 3J(P7H)ꢀ42.5 Hz,, 3J(H2H4)ꢀ
8.0 Hz, J(H1H2)ꢀ2.0 Hz, 1H, H2), 3.09
3.8 Hz, J(H1H5)ꢀ2.0 Hz, 1H, H5),
2.30 (ddd, 3J(PH)ꢀ24.0 Hz, 2J(H3H4)ꢀ
13.3 Hz,
3J(H3H5)ꢀ
3.8 Hz,1H, H3), 1.95 (s, 9H, CH3,
arene),1.91 (s, 3H, CH3), 1.57 (dddd, 3J(P7H)ꢀ
24.5
Hz, 3J(PH)ꢀ19.5 Hz, 2J(H3H4)ꢀ
9.0 Hz, 1H, H4), 1.41 (s, 3H, CH3).
13C{1H}-NMR (125.691 MHz, CD3NO2, 25 8C).
/
/
/
/
/
/
3
/
/
/
3
/
J(H1H5)ꢀ
/
2.0 Hz, 1H,
9.0
/
/
/
/
/
2
3
Hz, J(PH)ꢀ
/
/
/
/
4
4
(dd, J(H3H5)ꢀ
/
/
3J(PC)ꢀ
/
/
/
31P{1H}-NMR (202.329 MHz, CD3NO2, 25 8C).
2
/
Major: d 148.05 (d, J(PP)ꢀ
/
54.8 Hz, 1P, P7), 63.93
/
(d, 2J(PP)ꢀ
2J(PP)ꢀ
53.0 Hz, 1P, P7), 58.70 (d, J(PP)ꢀ
1P, P2).
/
54.8 Hz, 1P, P2); Minor: 153.29 (d,
2
/
/
13.3 Hz, 3J(H2H4)ꢀ
/
/
/
53.0 Hz,
2
3
d 138.84 (dd, J(PC)ꢀ
/
2.6 Hz, J(PC)ꢀ
/
1.0 Hz, C6),
4.3. Typical procedure for the transfer hydrogenation of
ketones
135.39 (bs, Co), 135.03 (d, 1J(PC)ꢀ
/
43.4 Hz, Ci), 132.03
4
2
(d, J(PC)ꢀ
/
9.0 Hz, Co), 131.70 (d, J(PC)ꢀ
/2.5 Hz,
Cp), 131.43 (d, 4J(PC)ꢀ
4J(PC)ꢀ2.4 Hz, Cp), 131,39 (dd, 1J(PC)ꢀ
3J(PC)ꢀ
/
2.6 Hz, Cp), 131.40 (d,
The catalyst precursors (0.05 mmol) and 2-propanol
(40 ml) were added to a three necked round bottom flask
and heated under reflux for 15 min. Then the ketone (10
mmol) and KOH solution in 10 ml of 2-propanol (0.25
mmol) were introduced successively into the solution.
The reaction mixture was stirred for the required
reaction time. Once the reaction was complete (mon-
itored by GC analysis) the solution was subjected to
flash chromatography or filtered through silica gel. The
solvent was removed by rotary evaporation to yield
clear liquids or white powders. The liquids were distilled
using a distillation apparatus under reduced pressure
(high boiling ketones), or subjected to GC analysis
(volatile ketones). The solids were analyzed by 1H-NMR
spectroscopy. All data are averages of two runs.
/
/30.7 Hz,
2
/
1.6 Hz, Ci), 130.70 (d, J(PC)ꢀ
/
15.3 Hz, C5),
3
3
129.10 (d, J(PC)ꢀ
/
9.8 Hz, Cm), 128.81 (d, J(PC)ꢀ
/
1
10.8 Hz, Cm), 128.30 (bs, Cm), 126.88 (d, J(PC)ꢀ
Hz, Ci), 121.04 (q, 1J(CF)ꢀ
320.9 Hz, CF3), 108.65 (dd,
J(PC)ꢀ2.4, 1.1 Hz, Cq), 97.47 (t, J(PC)ꢀ0.5 Hz, CH),
55.71 (dd, 1J(PC)ꢀ35.9 Hz, 2J(PC)ꢀ
12.2 Hz, C1),
49.02 (dd, 1J(PC)ꢀ34.4 Hz, 3J(PC)ꢀ
1.4 Hz, C4), 33.42
(dd, 1J(PC)ꢀ40.3 Hz, 2J(PC)ꢀ
2J(PC)ꢀ
9.9 Hz, J(PC)ꢀ
/
51.4
/
/
/
/
/
/
/
/
/
29.9 Hz, C2), 31.09 (dd,
2
/
/
1.9 Hz, C3), 17.41 (s, CH3,
arene), 13.82 (appt, 3J(PC)ꢀ4
/
J(PC)ꢀ
3.5 Hz, CH3).
31P{1H}-NMR (202.329 MHz, CD3NO2, 25 8C).
d 141.93 (d, 2J(PP)ꢀ
58.0 Hz, 1P, P7), 59.68 (d,
2J(PP)ꢀ
58.0 Hz, 1P, P2).
Compound 4: m.p. 283Á
/1.9 Hz, CH3),
3
12.27 (d, J(PC)ꢀ
/
/
/
/
285 8C, (80% yield); Anal.
4.4. X-ray data collection and processing
Calc. for C39H44ClF3O3P2RuS: C, 55.22; H, 5.22.
Found: C, 55.39; H, 5.18%.
1H-NMR (499.827 MHz, CD3NO2, 25 8C).
Crystals of the complexes, obtained from
nitromethaneÁether solvent mixtures were mounted on
/
d
7.83Á
3J(H1H2)ꢀ4
3J(PH)ꢀ41.0 Hz, 3J(H2H4)ꢀ
3J(H1H2)ꢀ
/
7.35 (m, 15H, Ph), 5.91, 3.97 (app t,
J(H1H5)ꢀ2.0 Hz, 1H, H1), 3.33 (ddddd,
9.0 Hz, 2J(PH)ꢀ
6.5 Hz,
3.0 Hz, J(H1H2)ꢀ0.5 Hz, 1H, H2), 3.06
4.0 Hz, J(H1H5)ꢀ2.0 Hz, 1H, H5),
2.26 (dddd, 3J(PH)ꢀ23.5 Hz, 2J(H3H4)ꢀ
13.5 Hz,
3J(H3H5)ꢀ
4.0 Hz, 1H, H3), 2.08 (s, 3H, CH3), 1.71
(s, 18H, CH3), 1.53 (dddd, 3J(PH)ꢀ23.5 Hz, 3J(PH)ꢀ
13.5 Hz, J(H2H4)ꢀ9.0 Hz, 1H,
H4), 1.36 (s, 3H, CH3).
glass fibers, coated with epoxy, and placed on a Siemens
P4 diffractometer. Intensity data were taken in the v-
/
/
/
/
/
mode at 298 K with MoÁKa graphite monochromated
/
3
˚
0.71073 A). Three check reflections
/
/
radiation (lꢀ
monitored every 100 reflections showed random
(B2%) variation during the data collections. The data
/
4
4
(dd, J(H3H5)ꢀ
/
/
/
/
/
/
were corrected for Lorentz polarization effects and
absorption, except for 2, using an empirical model
derived from azimuthal data collections. Scattering
factors and corrections for anomalous dispersion were
/
/
2
3
20.0 Hz, J(H3H4)ꢀ
/
/

56
K.Y. Ghebreyessus, J.H. Nelson / Journal of Organometallic Chemistry 669 (2003) 48Á56
/
(b) K.-J. Haack, S. Hashiguchi, A. Fujii, T. Ikariya, R. Noyori,
Angew. Chem. Int. Ed. Engl. 36 (1997) 285;
taken from a standard source [19]. Calculations were
performed with the Siemens SHELXTL plus version 5.10
software package on a personal computer. The struc-
tures were solved by Patterson methods. Anisotropic
thermal parameters were assigned to all non-hydrogen
atoms. Hydrogen atoms were refined at calculated
(c) S. Hashiguchi, A. Fujii, K.-J. Haack, K. Matsumura, T.
Ikariya, R. Noyori, Angew. Chem. Int. Ed. Engl. 36 (1997) 288;
(d) A. Fujii, S. Hashiguchi, N. Uematsu, T. Ikariya, R. Noyori, J.
Am. Chem. Soc. 118 (1996) 2521;
(e) S. Hashiguchi, A. Fujii, J. Takehara, T. Ikariya, R. Noyori, J.
Am. Chem. Soc. 117 (1995) 7562.
positions with a riding model in which the CÃ
/
H vector
[5] (a) M. Palmer, T. Walsgrove, M. Wills, J. Org. Chem. 62 (1997)
5226;
˚
was fixed at 0.96 A. Compound 2 crystallized as a
nitromethane solvate.
(b) A. Katho´, D.J. Carmana, F. Viguri, C.D. Remacha, J.
Kova´cs, F. Joo´, L.A. Oro, J. Organomet. Chem. 593Á
/594
(2000) 299;
(c) Y.-G. Zhou, W. Tang, W.-B. Wang, W. Li, X. Zhang, J. Am.
Chem. Soc. 124 (2002) 4952;
5. Supporting material
(d) P. Dierkes, P.W.N.M. van Leeuwen, J. Chem. Soc. Dalton
Trans. (1999) 1519.;
Tables of X-ray data in CIF format for compounds 2,
3 and 4 have been deposited with the Cambridge
(e) R. Kadyrov, A. Borner, R. Selke, Eur. J. Inorg. Chem. (1999)
¨
705.
Crystallographic Data Center, nos. CCDC 196714Á
/
[6] K.D. Redwine, J.H. Nelson, J. Organomet. Chem. 613 (2000) 177.
[7] (a) L. Solujic´, E.B. Milosavljevic´, J.H. Nelson, N.-W. Alcock, J.
Fisher, Inorg. Chem. 28 (1989) 3453;
196716. Copies of this information may be obtained
free of charges from the Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (Fax: ꢁ44-1223-
/
(b) S. Affandi, J.H. Nelson, J. Fisher, Inorg. Chem. 28 (1989)
4536;
336033; e-mail: deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
(c) D. Bhaduri, J.H. Nelson, C.L. Day, R.A. Jacobson, L. Solujic´,
E.B. Milosavljevic´, Organometallics 11 (1992) 4069;
(d) H.L. Ji, J.H. Nelson, A. DeCian, J. Fisher, L. Solujic´, E.B.
Milosavljevic´, Organometallics 11 (1992) 1840;
(e) J.H. Nelson, in: L.D. Quin, J.G. Verkade (Eds.), Phosphorus-
31 NMR Spectral Properties in Compound Characterization and
Acknowledgements
This research was supported by an award from the
Research Corporation and by the donors of the
Petroleum Research Fund Administered by the Amer-
ican Chemical Society. We are grateful for this support.
Structural Analysis, VCH, Deerfield Beach, FL, 1994, pp. 203Á
214;
/
(f) K.D. Redwine, V.J. Catalano, J.H. Nelson, Syn. React. Inorg.
Met.-Org. Chem. 29 (1999) 395;
(g) K. Maitra, V.J. Catalano, J.H. Nelson, J. Am. Chem. Soc. 119
(1997) 12560.
[8] I.D.-L. Rios, M.J. Tenorio, M.A.J. Tenrio, M.C. Puetra, P.
Valerga, J. Organomet. Chem. 525 (1996) 57.
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(b) F. Gasolv, New J. Chem. 18 (1994) 19;
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