Five- and six-coordinate ruthenium(II) complexes containing 2-Ph2PC6H4CH=NtBu and 2-Ph2PC6H4CH2NHtBu as chelate ligands: Synthesis, characterization, and catalytic activity in transfer hydrogenation of ketones

Article abstract of DOI:10.1021/om010443r

Five- and six-coordinate ruthenium(II) complexes containing imino- and aminophosphines have been prepared by ligand exchange processes. Thus, reactions of [RuCl₂(PPh₃)₃] and [RuCl₂(DMSO)₄] with 2-Ph₂PC₆H₄CH=N^tBu (a) lead to [RuCl₂(κ²-P,N-2-Ph₂PC₆ H₄CH=N^tBu)(PPh₃)] (1a) and trans-[RuCl₂(κ²-P,N-2-Ph₂PC₆ H₄CH=N^tBu)(DMSO)₂] (2a), respectively. Similarly, reactions with 2-Ph₂PC₆H₄CH₂NH^tBu (b) afford complexes [RuCl₂(κ²-P,N-2-Ph₂PC₆ H₄CH₂NH^tBu)(PPh₃)] (5b) and [RuCl₂(κ²-P,N-2-Ph₂PC₆ H₄CH₂NH^tBu)(DMSO)] (6b) in good yield. The crystal structures of 1a and 5b have been determined by X-ray diffraction. Compound 2a, containing two labile DMSO ligands, has been used as a precursor to synthesize the derivatives [RuCl₂(κ²-P,N-2-Ph₂PC₆ H₄CH=N^tBu)L] [L = PPh₃ (1a); PPh₂Me (3a); PMe₂Ph (4a)]. Complexes 1a, 2a, 5b, and 6b are active in catalytic transfer hydrogenation of aryl-alkyl and dialkyl ketones in propan-2-ol. The five-coordinate complexes 1a, 5b, and 6b show higher catalytic activity than the octahedral complex 2a. Complexes 1a and 5b are more efficient catalysts than the precursor complex [RuCl₂ (PPh₃)₃]. For the best catalyst, 1a, yields up to 91% were obtained and turnover frequencies may be as high as 41 400 h^-1.

Full text of DOI:10.1021/om010443r

Organometallics 2001, 20, 4369-4377
4369
F ive- a n d Six-Coor d in a te Ru th en iu m (II) Com p lexes
Con ta in in g 2-P h 2P C6H4CHdNtBu a n d
2-P h 2P C6H4CH2NHtBu a s Ch ela te Liga n d s: Syn th esis,
Ch a r a cter iza tion , a n d Ca ta lytic Activity in Tr a n sfer
Hyd r ogen a tion of Keton es
Pascale Crochet,† J ose´ Gimeno,*,† Santiago Garc´ıa-Granda,‡ and J avier Borge‡
Instituto Universitario de Quı´mica Organometa´lica “Enrique Moles” (Unidad Asociada al
CSIC), Departamento de Quı´mica Orga´nica e Inorga´nica, Facultad de Quı´mica, Universidad
de Oviedo, 33006 Oviedo, Spain, and Departamento de Qu´ımica Fı´sica y Analı´tica, Facultad
de Quı´mica, Universidad de Oviedo, 33006 Oviedo, Spain
Received May 25, 2001
Five- and six-coordinate ruthenium(II) complexes containing imino- and aminophosphines
have been prepared by ligand exchange processes. Thus, reactions of [RuCl2(PPh3)3] and
[RuCl2(DMSO)4] with 2-Ph2PC6H4CHdNtBu (a ) lead to [RuCl2(κ2-P,N-2-Ph2PC6H4CHdNt-
Bu)(PPh3)] (1a ) and trans-[RuCl2(κ2-P,N-2-Ph2PC6H4CHdNtBu)(DMSO)2] (2a ), respectively.
Similarly, reactions with 2-Ph2PC6H4CH2NHtBu (b) afford complexes [RuCl2(κ2-P,N-2-Ph2-
PC6H4CH2NHtBu)(PPh3)] (5b) and [RuCl2(κ2-P,N-2-Ph2PC6H4CH2NHtBu)(DMSO)] (6b) in
good yield. The crystal structures of 1a and 5b have been determined by X-ray diffraction.
Compound 2a , containing two labile DMSO ligands, has been used as a precursor to
synthesize the derivatives [RuCl2(κ2-P,N-2-Ph2PC6H4CHdNtBu)L] [L ) PPh3 (1a ); PPh2Me
(3a ); PMe2Ph (4a )]. Complexes 1a , 2a , 5b, and 6b are active in catalytic transfer
hydrogenation of aryl-alkyl and dialkyl ketones in propan-2-ol. The five-coordinate complexes
1a , 5b, and 6b show higher catalytic activity than the octahedral complex 2a . Complexes
1a and 5b are more efficient catalysts than the precursor complex [RuCl2(PPh3)3]. For the
best catalyst, 1a , yields up to 91% were obtained and turnover frequencies may be as high
as 41 400 h-1
.
In tr od u ction
In contrast, to the best of our knowledge very few imino-
or aminophosphine ligands have been used for this type
of catalytic transformations. The first complexes, re-
cently reported by Noyori and co-workers, contain the
tetradentate C2-diphosphine/diimine and diphosphine/
diamine ligands N,N′-(S,S)-bis[o-(diphenylphosphino)-
benzylidene]cyclohexane-1,2-diamine (A) and N,N′-(S,S)-
bis[o-(diphenylphosphino)benzyl]cyclohexane-1,2-di-
amine (B).6 Interestingly, marked differences in activity
are observed between the sp2-N and the sp3-N ligands,
the iminophosphine complex being almost inactive in
the reduction of acetophenone, whereas the aminophos-
phine complex leads to a high conversion. The high
catalytic activity is attributed to the presence of the
amino N-H group in the ligand. Rhodium(I) complexes
containing these ligands have also shown a similar
behavior, i.e., a higher activity for the complex with the
diaminodiphosphine ligand.7 Moreover, ruthenium(II)
complexes containing an analogous tridentate NPN-type
ligand, which also bears two secondary amino groups,
have also been shown to catalyze the reduction of aryl-
alkyl or dialkyl ketones by 2-propanol.8
The catalytic hydride transfer reduction of ketones
has been largely investigated among those catalytic
processes with potential applications. Although phos-
phines were historically the first type of ligands used
in transition metal catalysts,1 it is now well-established
that the use of mixed phosphorus-nitrogen (P-N)
ligands has led to an increased activity.2 In particular,
many ruthenium(II) complexes bearing bidentate or
tridentate phosphinooxazoline as well as pyridylphos-
phine ligands have proved to be very efficient catalysts.2-5
† Instituto Universitario de Qu´ımica Organometa´lica “Enrique
Moles”.
‡ Departamento de Qu´ımica F´ısica y Anal´ıtica.
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10.1021/om010443r CCC: $20.00 © 2001 American Chemical Society
Publication on Web 09/12/2001

4370 Organometallics, Vol. 20, No. 21, 2001
Crochet et al.
ing related amino- and iminophosphines prompted us
to prepare new ruthenium(II) complexes incorporating
this type of ligand in order to enable comparative
studies on their catalytic activity. Since the iminophos-
phine a and its aminophosphine derivative b are readily
accessible16,17 in high yield and can be handled in air,
we believed it to be of interest to use them as ligands of
ruthenium(II) catalysts. Although a wide series of
palladium(II)18 and other transition metal complexes19
have been reported, as far as we know, no ruthenium-
(II) complexes containing bidentate iminophosphine
ligands 2-Ph2PC6H4CHdNR have been described to
date.20 Only some examples containing related tet-
radentate diimino/diphosphines Ph2PC6H4CHdN-X-
NdCHC6H4PPh2 (X ) C2H4, C3H6, C6H12, C6H10, dim-
ethylbiphenylene, binaphthylene)6,21 and tridentate
anionic Ph2PC6H4CHdN-Y (Y)C6H4O-,CHMeCHPhO-)22
ligands are known.
In addition to this type of catalyst, other complexes
bearing a wide variety of similar ligands such as
diamines,2,3,9 amino alcohols,2,10 amino acids,11 bisox-
azolines,2 phenanthrolines,2 diimines,2,12 imino alcohols,10g
aminosulfides,13 and iminopyridines2 have also proved
to be good catalysts in transfer hydrogenation of ke-
tones. Once again, the presence of an N-H group seems
to be crucial to obtain good activity.2b,9f,10c,g,14 The
acceleration effect of primary and secondary amines has
been explained on the basis of their ability to deliver
the hydrogen atom from the metal-hydride catalysts to
the ketones via a six-membered transition structure
involving the N-H moiety (structure C). This mecha-
nism has been supported by theoretical calculations.15
We report herein (i) the synthesis and characteriza-
tion of five- and six-coordinate novel ruthenium(II)
complexes containing the iminophosphine 2-Ph2PC6H4-
CHdNtBu (a ) and the related aminophosphine 2-Ph2-
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Transfer Hydrogenation of Ketones
Organometallics, Vol. 20, No. 21, 2001 4371
Sch em e 1
Sch em e 2
PC6H4CH2NHtBu (b) as ligands and (ii) a preliminary
study of their catalytic activity in hydrogen transfer
reactions to ketones.
the free ligand.23 Similarly, IR spectra show a slight
lowering of the ν(CdN) absorption (1634 cm-1 (a ) vs
1629 (1a ) and 1627 cm-1 (2a )). The presence of two
inequivalent phosphorus nuclei in complex 1a gives rise
to the expected AB pattern which appears at δ 81.6 and
35.7 (2J PP ) 33.4 Hz). The small value of the coupling
constant is consistent with a cis disposition of the two
1
phosphorus atoms. H and 13C{1H} NMR spectra of 2a
show the expected resonances arising from the presence
of the iminophosphine and DMSO ligands. They show
only two sets of proton and carbon resonances for the
methyl groups of the DMSO ligands, which is consistent
with a cis disposition. Furthermore, the far-infrared
(FIR) spectrum, which shows an absorption at 327 cm-1
(with a shoulder at 317 cm-1), indicates a trans ar-
rangement of the chloride ligands. No absorptions below
300 cm-1 are observed. All of these data support the
stereochemistry shown in Scheme 2.
Resu lts a n d Discu ssion
Syn t h esis of t h e Im in op h osp h in e Com p lexes
[Ru Cl2(K2-P ,N-2-P h 2P C6H4CHdNtBu )L] (L ) P P h 3
(1a ); P P h 2Me (3a ); P Me2P h (4a )) a n d tr a n s-[Ru Cl2-
(K2-P ,N-2-P h 2P C6H4CHdNtBu )(DMSO)2] (2a ). The
treatment of ruthenium(II) precursors [RuCl2(PPh3)3]
and [RuCl2(DMSO)4] with the iminophosphine a 16 yields
the desired ruthenium(II) complexes via ligand ex-
change processes. Thus, the reaction of [RuCl2(PPh3)3]
with 1 equiv of a in THF results in the formation of the
five-coordinate complex [RuCl2(κ2-P,N-2-Ph2PC6H4CHd
NtBu)(PPh3)] (1a ) (Scheme 1).
Similarly the hexacoordinate complex trans-[RuCl2-
(κ2-P,N-2-Ph2PC6H4CHdNtBu)(DMSO)2] (2a ) is ob-
tained from the reaction of [RuCl2(DMSO)4] with 1 equiv
of a (Scheme 2). All attempts to synthesize the bis-
(iminophosphine) complex [RuCl2(κ2-P,N-2-Ph2PC6H4-
CHdNtBu)2] by treatment of either [RuCl2(PPh3)3] or
[RuCl2(DMSO)4] with a large excess of 2-Ph2PC6H4CHd
NtBu in refluxing THF failed. Monitoring the reaction
by 31P{1H} NMR the formation of only 1a or 2a is
observed. This behavior reflects the steric requirements
of the iminophosphine ligand a .
To determine unambiguously the stereochemistry of
1a , an X-ray diffraction study was carried out. An
ORTEP drawing of 1a is shown in Figure 1, and selected
bond lengths and angles are collected in Table 1. As for
the precursor [RuCl2(PPh3)3],24 the coordination geom-
etry around the ruthenium atom in 1a can be described
as a distorted square pyramid, with the phosphorus
atom [P(2)] of the PPh2 group at the apical position. The
base of the pyramid is formed by the two chloride atoms
occupying opposite sites [Cl(1)-Ru-Cl(2) ) 167.39 (6)°]
and by the nitrogen of the imino group in trans position
to the triphenylphosphine ligand [N-Ru-P(1) ) 166.02
(15)°]. The ruthenium atom is 0.2470 Å above the best
least-squares base plane. The metallacycle formed by
the iminophosphine ligand is almost planar. The devia-
tions from the best plane are -0.00167 (Ru), -0.01597
[P(2)], 0.002009 [C(61)], 0.00220 [C(66)], -0.03356
[C(67)], and 0.02890 (N) Å. The Ru-N and C(67)-N
bond lengths, 2.082(6) and 1.255(9) Å, respectively, are
similar to those found in [RuCl2(κ4-P,N,N′,P′-Ph2PC6H4-
CHdNCH2CH2NdCHC6H4PPh2)] [2.094(9), 2.097(6) and
The stoichiometry of the five- and six-coordinate
complexes 1a and 2a , respectively, is supported by
1
elemental analysis and IR, 31P{1H}, H, and 13C{1H}
NMR spectroscopic data (see Experimental Section for
details), which are also consistent with a chelate coor-
dination of the iminophosphine ligand. This is readily
assessed by the NMR spectra which show a downfield
shifting of the phosphorus resonances as well as those
of carbon and proton of the imino group with respect to
4
(23) For the free ligand, in CDCl3, δCHdN, 8.78 (d, J PH ) 4.8 Hz);
3
δCHdN, 154.4 (d, J PC ) 20.3 Hz); δ31P{1H}, -11.7 (s).
(24) La Placa, S. J .; Ibers, J . A. Inorg. Chem. 1965, 4, 778.

4372 Organometallics, Vol. 20, No. 21, 2001
Crochet et al.
phosphine. Similar coupling constant values are found
for 1a and in a series of palladium(II)18f,n and iridium-
(I)19f complexes in which the imino group is also located
trans to a phosphorus.25
Syn th esis of th e Am in op h osp h in e Com p lexes
[Ru Cl2(K2-P ,N-2-P h 2P C6H4CH2NHtBu )L] (L ) P P h 3
(5b); DMSO (6b)). Reactions of 1 equiv of the amino-
phosphine b17 with [RuCl2(PPh3)3] and [RuCl2(DMSO)4]
in THF lead to the formation of the five-coordinate
complexes [RuCl2(κ2-P,N-2-Ph2PC6H4CH2NHtBu)(PPh3)]
(5b, 85%) and [RuCl2(κ2-P,N-2-Ph2PC6H4CH2NHtBu)-
(DMSO)] (6b, 92%), respectively (Schemes 4 and 5).
Complexes 5b and 6b have been characterized by
1
elemental analysis, IR, and 31P{1H}, H, and 13C{1H}
1
NMR spectroscopy. In particular, the H NMR spectra
show the NH resonance at δ 4.71 (5b) and 4.46 (6b) ppm
and two signals at δ 4.46 and 4.00 (5b) ppm, and 4.38
and 4.06 (6b) ppm attributable to the two diastereotopic
CH2N protons. The inequivalence of the methylene
protons arises from the coordination of the amino group,
which converts the nitrogen atom in a stereogenic
center. Therefore no cleavage of the Ru-N bond, which
would lead to an inversion of the configuration around
the N atom, is taking place on the NMR time scale. The
X-ray crystal structure determination of 5b confirms the
presence of a pair of enantiomers (see below). The 31P-
{1H} NMR spectrum of 5b exhibits as for the analogous
F igu r e 1. ORTEP view of the iminophosphine complex
1a . Thermal ellipsoids are shown at 30% probability.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 1a
Bond Lengths
Ru-N
Ru-P(1)
Ru-P(2)
2.082(6)
2.362(4)
2.203(3)
Ru-Cl(1)
Ru-Cl(2)
C(67)-N
2.398(4)
2.401(4)
1.255(9)
Bond Angles
complex 1a an AB pattern at δ 73.4 and 40.1 (2J PP
)
N-Ru-P(1)
N-Ru-P(2)
P(2)-Ru-P(1)
N-Ru-Cl(1)
166.02(15)
94.53(18)
99.17(10)
87.0(2)
N-Ru-Cl(2)
P(2)-Ru-Cl(1)
P(2)-Ru-Cl(2)
Cl(1)-Ru-Cl(2)
85.8(2)
98.05(11)
92.82(11)
167.39(6)
37.3 Hz) indicating a cis arrangement of the two
phosphorus atoms. Although the spectroscopic data of
complex 6b do not allow us to assess unambiguously
its stereochemistry, an analogous trans arrangement for
both chloride ligands and DMSO-amine group is pro-
posed.
Torsion Angles
-0.6(3) C(66)-C(67)-N-Ru 7.8(12)
N-Ru-P(2)-C(61)
Ru-P(2)-C(61)-C(66) 2.6(6) P(2)-Ru-N-C(67) -4.3(7)
C(61)-C(66)-C(67)-N -4.9(12)
The structure of complex 5b was confirmed by X-ray
diffraction. An ORTEP drawing of 5b is shown in Figure
2, and selected bond lengths and angles are collected
in Table 2. Similarly to 1a , the coordination geometry
around the ruthenium atom in 5b can be described as
a distorted square pyramid, with the phosphorus atom
[P(2)] of the PPh2 group at the apical position. The base
of the pyramid is formed by the two chloride atoms
occupying opposite sites [Cl(2)-Ru-Cl(1) ) 164.61(3)°]
and by the nitrogen in trans position to the triph-
enylphosphine ligand [N-Ru-P(1) ) 169.87(6)°]. The
deviations from the best plane are -0.0317 [P(1)],
0.0349 [Cl(1)], 0.0354 [Cl(2)], and -0.0386 (N) Å. The
ruthenium atom is -0.2356 Å above this plane. The
Ru-N bond length, 2.225(2) Å, which is longer than that
of the imino complex 1a , is similar to those found in
[RuCl2(κ3-P,N,N′-(S,S )-Ph 2PC6H 4CH 2NH C6H 10NH -
CH2C6H4PPh2)] [2.157(9) and 2.231(8) Å],21d [RuCl2
(κ4-P ,N ,N ′,P ′-P h 2P C6H 4CH 2N H C2H 4N H CH 2C6H 4-
PPh2)] [2.177(1) and 2.16(1) Å],21b and [RuCl2(κ4-P,N,
N ′,P ′-(S ,S )-P h 2 P C6 H 4 CH 2 N H C6 H 1 0 N H CH 2 C6 H 4 -
PPh2)].6 As expected, the planarity of the metallacycle
found in complex 1a is no longer observed in complex
5b due to the transformation of the sp2-N imino to sp3-N
amino group. It is worth drawing attention to the very
short Cl(1)‚‚‚HN distance of 2.43(3) Å (expected van der
Waals separation, 3.0 Å), which is ascribed to an
1.297(9), 1.285(9) Å],21a [RuCl2(κ4-P,N,N′,P′-(S,S)-Ph2-
PC6H4CHdNC6H10NdCHC6H4PPh2)] [2.100(5), 2.091-
(5) and 1.273(8), 1.272(8) Å],6 and [Ru(κ3-P,N,O-(S,R)-
Ph2PC6H4CHdNCHMeCHPhO)2] [2.059(5) and 1.303(8)
Å].22
The lability of DMSO ligands in complex 2a allows
their substitution by phosphines with relatively small
cone angles. Thus, the reaction of 2a with 1 equiv of
PPh3, in toluene at room temperature, leads to the
displacement of both DMSO ligands to afford 1a .
Similarly, PPh2Me and PMe2Ph react with 2a to afford
the related complexes [RuCl2(κ2-P,N-2-Ph2PC6H4CHd
NtBu)(PPh2Me)] (3a , 88%) and [RuCl2(κ2-P,N-2-Ph2-
PC6H4CHdNtBu)(PMe2Ph)] (4a , 89%), respectively
(Scheme 3). In contrast no reaction is observed when
the bulkier phosphine PiPr3 is used.
Complexes 3a and 4a are fully characterized by
1
elemental analyses and spectroscopic methods (IR, H,
31P{1H}, and 13C{1H} NMR). The following features
from the NMR spectra are noteworthy: (a) the 31P{1H}
NMR spectra show resonances of an AB system [86.3
2
and 24.7 (3a ); 86.2 and 19.3 (4a ) ppm]. The small J PP
value (36.7 Hz) is consistent with the cis disposition of
both P-donor fragments. (b) The CHdN resonance in
the 1H NMR spectra appears as a doublet with an
appreciable coupling to the phosphorus nuclei of PPh2-
Me or PMe2Ph (4J PH ) 9.7 Hz), as confirmed by
1
heteronuclear H-31P NMR correlation. This coupling
(25) 4J PH values for cis arrangement in the range 0-4.9 Hz. For
references see for example 19c,e, 20g, and 22.
constant suggests that the CHdN group is trans to the

Transfer Hydrogenation of Ketones
Organometallics, Vol. 20, No. 21, 2001 4373
Sch em e 3
Sch em e 4
Sch em e 5
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 5b
Bond Lengths
Ru-N
Ru-P(1)
Ru-P(2)
2.225(2)
2.3318(7)
2.1943(7)
Ru-Cl(1)
Ru-Cl(2)
N-H
2.4020(7)
2.3727(7)
0.86(3)
Bond Angles
N-Ru-P(1)
NRu-P(2)
P(2)-Ru-P(1)
N-Ru-Cl(1)
169.87(6)
91.94(6)
98.16(3)
80.22(7)
N-Ru-Cl(2)
P(2)-Ru-Cl(1)
P(2)-Ru-Cl(2)
Cl(1)-Ru-Cl(2)
90.48(7)
95.38(3)
97.19(2)
164.61(3)
Torsion Angles
29.95(1) C(66)-C(67)-N-Ru -71.5(3)
Ru-P(2)-C(61)-C(66) -47.5(2) P(2)-Ru-N-C(67) -155.1(3)
C(61)-C(66)-C(67)-N 65.4(3)
N-Ru-P(2)-C(61)
The formation of the aminophosphine five-coordinate
complex [RuCl2(κ2-P,N-2-Ph2PC6H4CH2NHtBu)(DMSO)]
(6b) containing only one DMSO ligand contrasts with
that of the six-coordinate complex [RuCl2(κ2-P,N-2-Ph2-
PC6H4CHdNtBu)(DMSO)2] (1a ), probably reflecting the
higher steric hindrance induced by the aminophosphine
b.
Ca ta lytic Tr a n sfer Hyd r ogen a tion of Keton es.
Preliminary catalytic studies on the transfer hydroge-
nation of CdO bonds by propan-2-ol using the complexes
1a , 2a , 5b, and 6b as catalysts have been performed.
The coordination of the chelate imino- and aminophos-
phine ligands in the identical ruthenium moiety [RuCl2-
(PPh3)] allows comparative studies. In a typical experi-
ment, the ruthenium(II) catalyst precursor (0.2 mol %)
F igu r e 2. ORTEP view of the aminophosphine complex
5b. Hydrogen atoms except NH have been omitted for
clarity. Thermal ellipsoids are shown at 30% probability.
intramolecular hydrogen bond.26 Another indication of
the bonding interaction between the hydrogen and the
chlorine is the fact that the amine hydrogen lies in the
plane of N, Cl(1), and Ru, thus minimizing the NH‚‚‚
Cl(1) distance [Cl(1)-Ru-N-H ) 5.88 (2.23)°].
(26) (a) Fryzuk, M. D.; Montgomery, C. D.; Rettig, S. J . Organome-
tallics 1991, 10, 467. (b) Haack, K.-J .; Hashiguchi, S.; Fujii, A.; Ikariya,
T.; Noyori, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 285.

4374 Organometallics, Vol. 20, No. 21, 2001
Crochet et al.
Ta ble 3. Tr a n sfer Hyd r ogen a tion of
Acetop h en on ea ,b
Since the nature of the base induces in some cases a
change in the catalytic activity of the system,28 we have
investigated the transfer hydrogenation of acetophenone
in the presence of different bases (no reduction of the
ketone is observed in the absence of base). Selected
results are summarized in Table 5. Addition of inorganic
bases, like NaOH, K2CO3, or NaCO2H, leads to similar
final conversions (entries 15-17), but the highest rate
is observed when sodium hydroxide is employed. In
contrast, the use of an organic base such as Et3N leads
to only very low conversions even when a high concen-
tration is used.
entry
catalyst
T [°C] yield [%]c time [min]
TOFd
1
2
3
4
5
6
7
8
9
1a
5b
2a
6b
90
90
90
90
90
70
70
50
50
81.1 (91.4)
79.4 (91.4)
25.8 (64.2)
27.5 (87.9)
27.0 (89.9)
33.6 (80.1)
23.9 (72.9)
17.5 (30.8)
10.1 (26.4)
5 (30)
5 (30)
5070 (910)
4960 (910)
760 (40)
10 (450)
10 (450)
5 (115)
5 (200)
5 (285)
10 (120)
10 (330)
810 (60)
[RuCl2(PPh3)3]
1690 (230)
2100 (120)
1500(80)
520 (80)
1a
5b
1a
5b
300 (20)
a
Conditions: reactions were carried out in a sealed tube at the
indicated temperature using 7 mL of propan-2-ol, 5 mmol of
acetophenone, 0.2 mol % of catalyst precursor, and 0.5 mol % of
Con clu sion s
b
NaOH. Values in parentheses refer to results obtained after
prolonged reaction time. c Yield of 1-phenylethanol, GC deter-
We have prepared the first ruthenium(II) complexes
containing non-oxazoline bidentate iminophosphines
[RuCl2(κ2-P,N-2-Ph2PC6H4CHdNtBu)L] (L ) PPh3 (1a );
PPh2Me (3a ); PMe2Ph (4a )) and the related aminophos-
phine derivatives [RuCl2(κ2-P,N-2-Ph2PC6H4CH2NHt-
Bu)L] (L ) PPh3 (5b); DMSO (6b)). The steric hindrance
of the bidentate ligands 2-Ph2PC6H4CHdNtBu (a ) and
2-Ph2PC6H4CH2NHtBu (b) seems to govern the stoichi-
ometry of the resulting complexes, giving rise prefer-
entially to five-coordinate complexes. Only one six-
coordinate derivative trans-[RuCl2(κ2-P,N-2-Ph2PC6-
H4CHdNtBu)(DMSO)2] (2a ) is obtained with the less
sterically demanding iminophosphine ligand. The fol-
lowing features are noteworthy in these complexes: (i)
All the five-coordinate complexes [RuCl2(κ2-P-N)L]
have been obtained stereoselectively with the monoden-
tate ligand in trans position to the imino or amino group.
(ii) These complexes provide a series of related imino-
and aminophosphine complexes active in transfer hy-
drogen reactions of ketones. They are unusual examples
where the influence of the imino -CHdNR and amino
-CH2-NHR groups on the catalytic activity can be
directly compared.
Complexes 1a , 2a , 5b, and 6b in the presence of base
are active catalysts in transfer hydrogenation of ke-
tones. In particular the catalytic activity of 1a and 5b
is higher than that found for the phosphine complex
[RuCl2(PPh3)3],27 and the observed conversions can be
compared to those found for other octahedral and five-
coordinate ruthenium(II) complexes with analogous
tridentate ligands.4a,5a,29 As expected, the iminophos-
phine complex 1a and the related aminophosphine
derivative 5b exhibit different catalytic activity. Nev-
ertheless, as far as we know, this is the first example
where an imino complex proves to be more efficient than
the corresponding amino derivative. Indeed, previous
comparative studies between imino- and aminophos-
phine,6 or imino and amino alcohol,10g have both con-
cluded that amino ligands lead to better activity.
Further enantioselective transfer hydrogen reactions
using chiral imino- and aminophosphines are currently
under investigation.
d
mined. Turnover frequency: moles of product per mole of catalyst
per hour, in h-1
.
and base (NaOH, 0.5 mol %) were added to a 0.71 M
solution of the ketone in iPrOH, the reaction being
monitored by gas chromatography. Selected results for
the reduction of acetophenone at different temperatures
are reported in Table 3. For comparative purposes the
catalytic activity of the complex [RuCl2(PPh3)3], which
has been previously studied by Ba¨ckvall and co-work-
ers,27 has been also examined under the same condi-
tions. The substitution in [RuCl2(PPh3)3] of two PPh3
ligands by one P-N chelate iminophosphine (a ) or
aminophosphine ligand (b) in complexes 1a and 5b,
respectively, induces an increase of the catalytic activ-
ity: 81.1% and 79.4% vs 27.0% of conversion in 5 min
(entries 1, 2, and 5) at 90 °C. On the basis of Noyori’s
results,6,15a a marked increase in activity should be
expected for the aminophosphine complex 5b, with
respect to the iminophosphine derivative 1a . Neverthe-
less, the rates observed at 90 °C for 1a and 5b are
similar. Moreover, complex 1a becomes more efficient
than 5b when the reaction is carried out at lower
temperature (70 or 50 °C): TOF value of 520 h-1 vs 300
h-1 after 10 min at 50 °C. As far as we know, this is the
first example where an imino complex proves to be more
active than the corresponding amino derivative. These
results seem to indicate that the NH group does not
participate in the interaction with the ketone through-
out the catalytic cycle.
Complexes 2a and 6b, containing DMSO ligands, are
less efficient than [RuCl2(PPh3)3] and afford only 25.8%
and 27.5% yield after 10 min (entries 3 and 4), the rate
observed for the aminophosphine complex 6b being
slightly higher than that for the iminophosphine deriva-
tive 2a . However this difference is most probably due
to the presence of a free coordination site in complex
6b rather than an effect of the NH group. Since the
coordination of the substrate on the ruthenium catalyst
is generally proposed during the catalytic cycle, it is not
surprising that the five-coordinate complexes 1a , 5b, 6b,
and [RuCl2(PPh3)3] are all more efficient than the six-
coordinate complex 2a .Complexes 1a and 5b also show
good catalytic activity in the transfer hydrogenation of
2-methoxyacetophenone, ethyl methyl ketone, and cy-
clohexanone, as shown in Table 4. The conversions can
be compared to those found for acetophenone at 90 °C
(Table 3).
Exp er im en ta l Section
The manipulations were performed under an atmosphere
of dry nitrogen using vacuum-line and standard Schlenk
(28) Carmona, D.; Lahoz, F. J .; Atencio, R.; Oro, L. A.; Lamata, M.
P.; Viguri, F.; San, J ose´, E.; Vege, C.; Reyes, J .; J oo´, F.; Katho´, A. Chem.
Eur. J . 1999, 5, 1544.
(27) Chowdhury, R. L.; Ba¨ckvall, J .-E. J . Chem. Soc., Chem. Com-
mun. 1991, 1063.
(29) Dani, P.; Karlen, T.; Gossage, R. A.; Gladiani, S.; van Koten,
G. Angew. Chem., Int. Ed. 2000, 39, 743.

Transfer Hydrogenation of Ketones
Organometallics, Vol. 20, No. 21, 2001 4375
Sch em e 6
mL) was stirred for 2 h at room temperature. After evaporation
to dryness, the resulting residue was washed 3 times with 10
mL of a mixture of hexane and ether (1:1) to afford a dark red
solid. Yield: 0.86 g (93%). Anal. Found (calcd for C41H39Cl2-
NP2Ru): C, 63.01 (63.16); H, 5.27 (5.04); N, 1.65 (1.80). 31P-
{1H} NMR, CDCl3, δ: 81.6 (d, 2J PP ) 33.4, PPh2), 35.7 (d, 2J PP
Sch em e 7
1
4
) 33.4, PPh3). H NMR, CDCl3, δ: 8.99 (d, 1 H, J PH ) 9.7,32
CHdN), 7.65-7.05 (m, 29 H, ArH), 1.55 (s, 9 H, tBu). 13C{1H}
NMR, CDCl3, δ: 162.8 (d, 3J PC ) 4.5, CHdN), 135.1 (d, 2J PC
)
9.9, C-o, PPh3), 129.1 (s, C-p, PPh3), 127.4 (d, 3J PC ) 9.9, C-m,
PPh3), 137.1-125.2 (other aromatic carbons), 68.2 (s, CMe3),
28.3 (s, CMe3). IR (Nujol, cm-1), νCdN: 1629.
Syn th esis of [Ru Cl2(K2-P ,N-2-P h 2P C6H4CHdNtBu )(DM-
SO)2] (2a ). A mixture of [RuCl2(DMSO)4] (0.126 g, 0.26 mmol)
and 2-Ph2PC6H4CHdNtBu (0.108 g, 0.31 mmol) in 30 mL of
THF was refluxed for 5 h. The resulting dark red solution was
evaporated to dryness and the residue washed twice with 10
mL of a mixture of hexane and ether (1:1) to afford a red solid.
Yield: 0.150 g (86%). Anal. Found (calcd for C27H36Cl2NO2-
PRuS2): C, 48.01 (48.14); H, 5.28 (5.39); N, 1.97 (2.08). 31P-
techniques. All reagents were obtained from commercial
suppliers and used without further purification. Solvents were
dried by standard methods and distilled under nitrogen before
use. The compounds [RuCl2(PPh3)3],30 [RuCl2(DMSO)4],31 2-Ph2-
PC6H4CHdNHtBu,16 and 2-Ph2PC6H4CH2NHtBu17 were pre-
pared by following the methods previously reported. Since only
the hydrochloride salt of 2-Ph2PC6H4CH2NHtBu is spectro-
scopically described in the literature,17 we report herein the
full characterization. Gas chromatographic measurements
were made on Hewlett-Packard HP6890 equipment. A HP-
INNOWAX cross-linked poly(ethylene glycol) column (30 m,
250 µm) was used. Infrared spectra were recorded on a Perkin-
Elmer 1720-XFT or a Perkin-Elmer 599 IR spectrometer. The
C, H, and N analyses were carried out with a Perkin-Elmer
240-B microanalyzer. NMR spectra were recorded on a Bruker
AC300 or 300DPX instrument at 300 MHz (1H), 121.5 MHz
(31P), or 75.4 MHz (13C) using SiMe4 or 85% H3PO4 as standard.
DEPT experiments have been carried out for all the com-
pounds. Coupling constants J are given in hertz. Abbreviations
used: Ar, aromatic; s, singlet; d, doublet; vt, virtual triplet;
m, multiplet. Numbering used for the ligands:
1
{1H} NMR, CDCl3, δ: 80.3 (s). H NMR, CDCl3, δ: 8.88 (s br,
1 H, CHdN), 8.10-6.98 (m, 14 H, ArH), 2.97 (s, 6 H, Me), 2.62
(s, 6 H, Me), 1.70 (s, 9 H, tBu). 13C{1H} NMR, CDCl3, δ: 164.2
3
2
(d, J PC ) 5.3, CHdN), 137.8 (d, J PC ) 14.4, C-1), 137.0 (d,
2J PC ) 9.1, C-3), 134.9 (s, C-4, 5, or 6), 134.4 (d, J PC ) 9.8,
2
1
C-o), 132.7 (d, J PC ) 58.2, C-i), 131.6 (s, C-4, 5, or 6), 131.5
4
(d, J PC ) 7.6, C-4 or 6), 130.2 (d, J PC ) 2.3, C-p), 127.6 (d,
3J PC ) 11.3, C-m), 123.9 (d, J PC ) 50.6, C-2), 70.3 (s, CMe3),
1
44.4 (s, Me2SO), 41.0 (s, Me2SO),27.6 (s, CMe3). IR (Nujol,
cm-1): νCdN 1627; νRuCl 327 (with shoulder at 217).
Syn th esis of [Ru Cl2(K2-P ,N-2-P h 2P C6H4CHdNtBu )L] [L
) P P h 3 (1a ); P P h 2Me (3a ); P Me2P h (4a )] fr om 2a . 1a : A
solution of 2a (0.085 g, 0.13 mmol) in 10 mL of toluene was
treated with a solution of triphenylphosphine in toluene (0.07
M, 1.8 mL, 0.13 mmol) and stirred at room temperature for 8
h. After evaporation to dryness, the residue was washed twice
with 4 mL of a mixture of hexane/ether (1:1) and vacuum-
dried. Yield: 0.088 g (87%). 3a : Following the same procedure
using 0.097 g (0.14 mmol) of 2a and PPh2Me (26 µL, 0.14
mmol). Reaction time: 1 h. Yield: 0.088 g (88%). Anal. Found
(calcd for C36H37Cl2NP2Ru): C, 60.31 (60.25); H, 5.14 (5.20);
2
N, 2.00 (1.95). 31P{1H} NMR, C6D6, δ: 86.3 (d, J PP ) 36.7,
2
1
PPh2), 24.7 (d, J PP ) 36.7, PPh2Me). H NMR, C6D6, δ: 8.64
(d, 1 H, J PH ) 9.7,32 CHdN), 8.07-6.75 (m, 24 H, ArH), 1.62
4
(d, 3 H, 2J PH ) 8.8, PPh2Me), 1.50 (s, 9 H, tBu). 13C{1H} NMR,
3
1
CDCl3, δ: 162.4 (d, J PC ) 4.7, CHdN), 137.7 (d, J PC ) 12.8,
C-1), 136.7 (d, 2J PC ) 9.3, C-3), 135.9 (d, 1J PC ) 37.3, C-2), 134.8
(d, 1J PC ) 55.3, C-i), 134.5 (s, C-4, 5, or 6), 133.9 (d, 2J PC ) 9.3,
Sp ectr oscop ic Da ta of 2-P h 2P C6H4CH2NHtBu (b). 31P-
{1H} NMR, CDCl3, δ: -15.2 (s). 1H NMR, CDCl3, δ: 7.51-
6.83 (m, 14 H, ArH), 3.91 (s br, 2 H, NCH2), 1.02 (s, 9 H, tBu),
the NH proton is not observed. 13C{1H} NMR, C6D6, δ: 146.6
(d, 1J PC ) 23.4, C-2), 138.0 (d, 1J PC ) 11.3, C-i), 136.3 (d, 2J PC
2
C-o), 132.7 (d, J PC ) 8.7, C-o), 130.9 (s, C-4, 5, or 6), 130.8 (s,
C-4, 5, or 6), 129.4 (d, 4J PC ) 2.3, C-p), 129.1 (s, C-p), 127.9 (d,
3J PC ) 8.2, C-m), 127.3 (d, J PC ) 11.1, C-m), 125.5 (d, J PC
)
3
1
2
) 14.3, C-1), 134.4 (d, J PC ) 20.4, C-o), 133.8 (s, C-4, 5, or 6),
1
46.6, C-i), 68.5 (s, CMe3), 28.0 (s, CMe3), 9.57 (d, J PC ) 31.4,
PMe). IR (Nujol, cm-1), νCdN: 1623. 4a : Following the same
procedure using 0.100 g (0.15 mmol) of 2a and 21 µL (0.15
mmol) of PMe2Ph. Reaction time: 1 h. Yield: 0.088 g (89%).
Anal. Found (calcd for C31H35Cl2NP2Ru): C, 58.73 (58.80); H,
5.29 (5.38); N, 1.97 (2.14). 31P{1H} NMR, CDCl3, δ: 86.2 (d,
2
3
130.0 (d, J PC ) 5.3, C-3), 129.2 (s, C-4, 5, or 6), 128.9 (d, J PC
) 6.8, C-m), 128.8 (s, C-p), 127.3 (s, C-4, 5, or 6), 50.6 (s, CMe3),
46.1 (d, J PC ) 22.7, CH2N), 29.1 (s, CMe3). IR (Nujol, cm-1),
3
ν
N-H: 3312. HRMS m/z calcd. for C23H26NP (found): M+
)
347.18028 (347.18011).
Syn th esis of [Ru Cl2(K2-P ,N-2-P h 2P C6H4CHdNtBu )(P -
P h 3)] (1a ). A solution of [RuCl2(PPh3)3] (1.127 g, 1.18 mmol)
and 2-Ph2PC6H4CHdNtBu (0.435 g, 1.27 mmol) in THF (100
2J PP ) 36.7, PPh2), 19.3 (d, J PP ) 36.7, PMe2Ph). 1H NMR,
2
CDCl3, δ: 8.89 (d, 1 H, J PH ) 9.7,32 CHdN), 7.72-6.96 (m,
4
2
19 H, ArH), 1.51 (d, 6 H, J PH ) 9.1, PMe2Ph), 1.44 (s, 9 H,
(30) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth.
1970, 12, 237.
(31) Evans, I. P.; Spencer, A.; Wilkinson, G. J . Chem. Soc., Dalton
Trans. 1973, 204.
(32) Coupling with the phosphorus of PPh3, PPh2Me, or PMePh2 but
not with the phosphorus of the iminophosphine as confirmed by
heteronuclear 1H-31P NMR correlation.

4376 Organometallics, Vol. 20, No. 21, 2001
Ta ble 4. Tr a n sfer Hyd r ogen a tion of Keton es RR′CdOa ,b
Crochet et al.
entry
R, R′
catalyst
yield [%]
time [min]
TOF
10
11
12
13
2-MeOC6H4, Me
2-MeOC6H4, Me
Et, Me
1a
5b
1a
1a
73.7 (98.1)
63.7 (97.7)
70.3 (94.7)
69.0 (99.4)
10 (90)
10 (60)
10 (45)
0.5 (5)
2170 (330)
1870 (490)
2070 (630)
41400 (6230)
cyclohexanone
a
Conditions: reactions were carried out in a sealed tube at 90 °C using 7 mL of propan-2-ol, 5 mmol of substrate, 0.2 mol % of catalyst
b
precursor, and 0.5 mol % of NaOH. Values in parentheses refer to results obtained after prolonged reaction time.
Ta ble 5. Tr a n sfer Hyd r ogen a tion of Acetop h en on e
in th e P r esen ce of Differ en t Ba sesa ,b
X-r a y Diffr a ction Stu d ies of 1a a n d 5b. Crystals suitable
for X-ray diffraction analyses were obtained by slow diffusion
of hexane into a concentrated solution of the complexes in
toluene. Data collection, crystal, and refinement parameters
are collected in Table 6. The structures were solved by
DIRDIF-99.233 (Patterson methods and phase expansion). An
empirical absorption correction was applied using XABS2.34
Full-matrix least-squares refinement on Fo2 using SHELX9735
was performed. During the final stages of the refinement, the
positional parameters and the anisotropic thermal parameters
of the non-H atoms were refined. Atomic scattering factors
were taken from International Tables for X-ray Crystal-
lography (1974).36 Geometrical calculations were made with
PARST97.37 The crystallographic plots were made with PLA-
TON.38 All calculations were made at the University of Oviedo
on the X-ray group computers. This work was partially
supported by CICYT (BQU2000-0219).
entry
base
yield [%]
time [min]
TOF
14
15
16
17
18
without
NaOH
K2CO3
NaCO2H
NEt3
0
240
5 (30)
30 (210)
10 (195)
5 (240)
81.1 (91.4)
1.5 (92.4)
2.7 (92.5)
0.5 (6.4)
5070 (910)
20 (130)
80 (140)
30 (10)
a
Conditions: reactions were carried out at 90 °C with 5 mmol
b
of acetophenone, 0.2 mol % of 1a , and 0.5 mol % of base. Values
in parentheses refer to results obtained after prolonged reaction
time.
3
tBu). 13C{1H} NMR, CDCl3, δ: 162.0 (d, J PC ) 4.1, CHdN),
143.0-126.2 (m, aromatic carbons), 68.5 (s, CMe3), 27.9 (s,
CMe3), 11.9 (d, 1J PC ) 28.5, PMe2). IR (Nujol, cm-1), νCdN: 1621.
Syn t h esis of [R u Cl2(K2-P ,N-2-P h 2P C6H 4CH 2NH t Bu )-
(P P h 3)] (5b). Following the same procedure as for 1a , 5b was
prepared as a green solid, using [RuCl2(PPh3)3] (0.392 g, 0.41
mmol) and 2-Ph2PC6H4CH2NHtBu (0.263 g, 0.76 mmol) in 40
Cr ysta l Da ta for 1a . Data collection was performed on a
Nonius CAD-4 single-crystal diffractometer. Data were col-
lected with the ω-2θ scan technique and a variable scan rate,
with a maximum scan time of 60 s per reflection. The final
drift correction factors were between 0.97 and 1.06. On all
reflections, profile analysis39,40 was performed. Lorentz and
polarization corrections were applied, and the data were
reduced to Fo2 values. The unit cell parameters were obtained
from the least-squares fit of 25 reflections (with θ between 15°
and 19°). H atoms were geometrically placed riding on their
parent atoms with isotropic displacement parameters set to
1.2 times the Ueq of the atoms to which they are attached (1.5
for methyl groups).
mL of THF. Yield: 0.208 g (85%). Anal. Found (calcd for C41H41
-
Cl2NP2Ru): C, 62.87 (63.00); H, 5.42 (5.29); N, 1.77 (1.79). 31P-
{1H} NMR, CDCl3, δ: 73.4 (d, 2J PP ) 37.3, PPh2), 40.1 (d, 2J PP
1
) 37.3, PPh3). H NMR, CDCl3, δ: 7.64-6.54 (m, 29 H, ArH),
4.71 (br s, 1 H, NH), 4.46 (vt, 1 H, 2J HH ) 3J HH ) 10.1, NCH2),
3
2
4.00 (dd, 1 H, J HH ) 10.1, J HH ) 2.0, NCH2), 1.41 (s, 9 H,
tBu). 13C{1H} NMR, CDCl3, δ: 141.9 (d, 1J PC ) 12.8, C-1), 135.0
2
(d, J PC ) 9.8, C-o, PPh3), 131.7 (d, J PC ) 3.8, C-4, 5, or 6),
131.4 (d, J PC ) 2.3, C-4, 5, or 6), 130.5 (d, J PC ) 2.3, C-p PPh2),
130.1 (d, J PC ) 2.3, C-p PPh2), 129.6 (d, 4J PC ) 1.5, C-p, PPh3),
2
3
128.5 (d, J PC ) 7.8, C-3), 128.0 (d, J PC ) 9.1, C-m, PPh3),
3
127.3 (d, J PC ) 10.6, C-m, PPh2), 135.5-129.2 (m, other
2
The function minimized was [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2, w
3
aromatic carbons), 59.2 (s, CMe3), 52.6 (d, J PC ) 6.8, CH2N),
) 1/[σ2(Fo2) + (0.2000P)2 + 0.0000P], where P ) (Fo + 2Fc2)/3
2
28.9 (s, CMe3). IR (Nujol, cm-1), νN-H: 3192.
with σ2(Fo2) from counting statistics. The maximum shift-to-
Syn th esis of Ru Cl2(K2-P ,N-2-P h 2P C6H4CH2NHtBu )(DM-
SO) (6b). Following the same procedure as for 2a , 6b was
prepared as a purple solid (green in solution), using RuCl2-
(DMSO)4 (0.186 g, 0.38 mmol) and 2-Ph2PC6H4CH2NHtBu
(0.210 g, 0.60 mmol) in 40 mL of THF. Yield: 0.204 g (92 %).
Anal. Found (calcd for C25H32Cl2NOPRuS): C, 51.42 (51.46);
H, 5.62 (5.53); N, 2.51 (2.40). 31P{1H} NMR, CD2Cl2, δ: 73.7
esd ratio in the last full-matrix least-squares cycle was 0.000.
Cr ysta l Da ta for 5b. Data collection was performed on a
Nonius KappaCCD single-crystal diffractometer. Crystal-
detector distance was fixed at 29 mm, and a total of 1078
images were collected using the oscillation method (æ and ω
scans), with 2° oscillation and 40 s exposure time per image.
Data collection strategy was calculated with the program
COLLECT.41 Data reduction and cell refinement were per-
formed with the programs HKL DENZO and SCALEPACK.42
Unit cell dimensions were determined from 6493 reflections
1
(s). H NMR, CD2Cl2, δ: 7.65-6.89 (m, 14 H, ArH), 4.46 (d, 1
H, 3J HH ) 11.2, NH), 4.38 (vt, 1 H, 2J HH ) 3J HH ) 11.2, CH2N),
4.06 (d, 1 H, 2J HH ) 11.2, CH2N), 3.33 (s, 3 H, Me2SO), 2.56 (s,
3 H, Me2SO), 1.41 (s, 9 H, tBu). 13C{1H} NMR, CD2Cl2, δ: 142.4
1
2
1
(d, J PC ) 12.8, C-1), 135.0 (d, J PC ) 9.8, C-o), 133.2 (d, J PC
4
) 58.2, C-i), 133.0 (d, J PC ) 3.0, C-4, 5, or 6), 132.2 (d, J PC
)
(33) Beurskens, P. T.; Beurskens, G.; Gelder, R. de; Garc´ıa-Granda,
S.; Gould, R. O.; Israel, R.; Smits, J . M. M. The DIRDIF-99 program
system; Crystallography Laboratory, University of Nijmegen: The
Netherlands, 1999.
(34) Parkin, S.; Moezzi, B.; Hope, H. J . Appl. Crystallogr. 1995, 28,
53.
(35) Sheldrick, G. M. SHELXL97, A computer program for refine-
ment of crystal structures; University of Gottingen, 1997.
(36) International Tables for X-ray Crystallography; Kynoch Press:
Birmingham, 1974; Vol. IV (Present distributor: Kluwer Academic
Publishers: Dordrecht).
(37) Nardelli, M. J . Appl. Crystallogr. 1995, 28, 659.
(38) Spek, A. L. PLATON, A Multipurpose Crystallographic Tool;
Utrecht University: Utrecht, The Netherlands, 2001.
(39) Lehman, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A 1974,
30, 580.
2
4
2.3, C-p), 131.9 (d, J PC ) 9.8, C-3), 131.2 (d, J PC ) 2.3, C-p),
1
130.7 (d, J PC ) 3.0, C-4, 5, or 6), 130.0 (d, J PC ) 49.1, C-2),
1
129.3 (d, J PC ) 56.6, C-i), 129.1 (d, J PC ) 8.3, C-4, 5, or 6),
3
3
128.5 (d, J PC ) 11.3, C-m), 127.7 (d, J PC ) 11.3, C-m), 61.3
3
(s, CMe3), 58.8 (d, J PC ) 6.8, CH2N), 46.6 (s, Me2SO), 44.5 (s,
Me2SO), 27.8 (s, CMe3). IR (Nujol, cm-1), νN-H: 3166.
Gen er a l P r oced u r e for Ru th en iu m (II)-Ca ta lyzed Hy-
d r ogen Tr a n sfer Rea ction s. Under inert atmosphere the
ketone (5 mmol), the ruthenium catalyst precursor (0.01 mmol,
0.2 mol %), and 6 mL of propan-2-ol are introduced in a sealed
tube and heated at working temperature for 20 min. Then the
base, NaOH unless otherwise specified, is added (1 mL of a
0.025 M solution in propan-2-ol, 0.5 mol %) and the reaction
is monitored by gas chromatography. Corresponding alcohol
and acetone are the only products detected in all cases.
(40) Grant, D. F.; Gabe, E. J . J . Appl. Crystallogr. 1978, 11, 114.
(41) COLLECT; Nonius BV, 1997-2000.
(42) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.

Transfer Hydrogenation of Ketones
Organometallics, Vol. 20, No. 21, 2001 4377
Ta ble 6. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for 1a a n d 5b
1a
5b
empirical formula
fw
temperature
wavelength
cryst syst
space group
unit cell dimens
C
41H39Cl2NP2Ru‚C7H8
C41H41Cl2NP2Ru
781.66
871.78
200 (2) K
200 (2) K
0.71073 Å
1.5418 Å
triclinic
triclinic
P1h
P1h
a ) 10.55 (1) Å
b ) 10.66 (1) Å
c ) 19.17 (3) Å
R ) 104.8 (1)°
â ) 92.54 (8)°
γ ) 98.02 (9)°
2058 (5) Å3
a ) 10.5799 (3) Å
b ) 13.2989 (3) Å
c ) 13.8899 (3) Å
R ) 107.635 (2)°
â ) 93.764 (1)°
γ ) 91.728 (2)°
1855.89 (8) Å3
2
volume
Z
2
density (calcd)
1.407 Mg m-3
1.399 Mg m-3
5.779 mm-1
804
abs coeff
0.624 mm-1
F(000)
900
cryst size
0.40 × 0.16 × 0.13 mm
0.17 × 0.12 × 0.12 mm
θ range for data collection
1.10 f 26.0
3.35 f 69.81
index ranges
-12 e h e 12, -13 e k e 12, 0 e l e 23
8484
-12 e h e 12, -16 e k e 15, 0 e l e 16
32 322
no. of reflns collected
no. of ind reflns
completeness to θ
abs corr
7632 [R(int) ) 0.0600]
26.00°, 94.4%
empirical
6945 [R(int) ) 0.0360]
69.81°, 99.0%
empirical
max. and min. transmn
refinement method
no. of data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
largest diff peak and hole
0.686 and 1.000
full-matrix least-squares on F2
7632/0/487
0.515 and 1.000
full-matrix least-squares on F2
6945/0/436
1.128
1.161
R1 ) 0.0660, wR2 ) 0.1925
R1 ) 0.0999, wR2 ) 0.2583
2.185 and -3.208 e Å-3
R1 ) 0.0328, wR2 ) 0.0925
R1 ) 0.0349, wR2 ) 0.0938
0.547 and -0.567 e Å-3
between θ ) 1.000° and 70.000°. Final mosaicity was 0.389-
(3)°. All data completeness was 99.0%. Intensity-error ratio
for all reflections was 299.5:8.8. H atoms (except H, H67A, and
H67B, which were detected by difference Fourier synthesis and
isotropically refined with an independent thermal parameter)
were geometrically placed riding on their parent atoms with
isotropic displacement parameters set to 1.2 times the Ueq of
the atoms to which they are attached (1.5 for methyl groups).
Ack n ow led gm en t. This work was supported by
fonds from FEDER (1FD97-0565).
Su p p or tin g In for m a tion Ava ila ble: Crystal structure
data for 1a and 5b including tables of atomic parameters,
anisotropic thermal parameters, bond distances, and bond
angles. This material is available free of charge via the
Internet at http://pubs.acs.org.
The function minimized was [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2, w
2
) 1/[σ2(Fo2) + (0.0434P)2 + 1.6695P], where P ) (Fo + 2Fc2)/3
2
with σ2(Fo2) from counting statistics. The maximum shift-to-
OM010443R
esd ratio in the last full-matrix least-squares cycle was 0.001.