Novel ruthenium(II) complexes containing imino- or aminophosphine ligands for catalytic transfer hydrogenation

Article abstract of DOI:10.1039/b206119h

Five- and six-coordinate ruthenium(II) complexes containing imino- and aminophosphines have been prepared by ligand exchange processes. Thus, reactions of [RuCl₂(PPh₃)₃] with 2-Ph₂PC₆H₄CH=NR (R = Ph (1a); 2′,6′-C₆H₃Me₂ (1b); 2′-C₆H₄OMe (1c)) lead to the chelate iminophosphine complexes [RuCl₂(κ²-P,N-2-Ph₂PC₆H ₄CH=NR)(PPh₃)] (R = Ph (3a); 2′,6′-C₆H₃Me₂ (3b)) and [RuCl₂(κ³-P,N,O-2-Ph₂PC₆H ₄CH=N-2′-C₆H₄OMe)(PPh₃)] (3c), respectively. Similarly, reactions with aminophosphine ligands 2-Ph₂PC₆H₄CH₂NHR (R = Ph (2a); ⁱPr (2d); (S)-CHMeCy (2e)) afford the 16-electron complexes [RuCl₂(κ²-P,N-2-Ph₂PC₆H ₄CH₂NHR)(PPh₃)] (R = Ph (5a); ⁱPr (5d); (S)-CHMeCy (5e)). The iminophosphines 2-Ph₂PC₆H₄CH=NR (R = ⁱPr (1d); (S)-CHMeCy (1e)) react with [RuCl₂(DMSO)₄] to lead to the bis-iminophosphine complexes [RuCl₂(κ²-P,N-2-Ph₂PC₆H ₄CH=NR)₂] (R = ⁱPr (4d); (S)-CHMeCy (4e)). The crystal structure of 4d has been determined by X-ray diffraction. Complexes 3a-c, 4d,e and 5a,d,e are active in catalytic transfer hydrogenation of acetophenone. All of them are more efficient than the precursor [RuCl₂(PPh₃)₃].

Full text of DOI:10.1039/b206119h

View Article Online / Journal Homepage / Table of Contents for this issue
Novel ruthenium(II) complexes containing imino- or aminophosphine
ligands for catalytic transfer hydrogenation
a
Pascale Crochet, Jose Gimeno,* Javier Borge and Santiago Garcıa-Granda
a
b
b
´
´
a
´
Instituto Universitario de Quımica Organometalica ‘‘Enrique Moles’’
(Unidad Asociada al CSIC), Departamento de Quımica Organica e Inorganica,
´
´
´
´
´
Facultad de Quımica, Universidad de Oviedo, 33006 Oviedo, Spain
Departamento de Quımica Fısica y Analıtica, Facultad de Quımica, Universidad de Oviedo,
b
´
´
´
´
33006 Oviedo, Spain
Received (in Strasbourg, France) 20th June 2002, Accepted 20th September 2002
First published as an Advance Article on the web 9th December 2002
Five- and six-coordinate ruthenium(II) complexes containing imino- and aminophosphines have been prepared
=
by ligand exchange processes. Thus, reactions of [RuCl2(PPh3)3] with 2-Ph2PC6H4CH NR (R ¼ Ph (1a);
20,60-C6H3Me2 (1b); 20-C6H4OMe (1c)) lead to the chelate iminophosphine complexes [RuCl2(k2-P,N-2-
3
0
0
=
=
Ph2PC6H4CH NR)(PPh3)] (R ¼ Ph (3a); 2 ,6 -C6H3Me2 (3b)) and [RuCl2(k -P,N,O-2-Ph2PC6H4CH
N-20-C6H4OMe)(PPh3)] (3c), respectively. Similarly, reactions with aminophosphine ligands
i
2-Ph2PC6H4CH2NHR (R ¼ Ph (2a); Pr (2d); (S)-CHMeCy (2e)) afford the 16-electron complexes
[RuCl2(k2-P,N-2-Ph2PC6H4CH2NHR)(PPh3)] (R ¼ Ph (5a); iPr (5d); (S)-CHMeCy (5e)). The iminophosphines
i
=
2-Ph2PC6H4CH NR (R ¼ Pr (1d); (S)-CHMeCy (1e)) react with [RuCl2(DMSO)4] to lead to the
2
i
=
bis-iminophosphine complexes [RuCl2(k -P,N-2-Ph2PC6H4CH NR)2] (R ¼ Pr (4d); (S)-CHMeCy (4e)).
The crystal structure of 4d has been determined by X-ray diffraction. Complexes 3a–c, 4d,e and 5a,d,e are active
in catalytic transfer hydrogenation of acetophenone. All of them are more efficient than the precursor
[RuCl2(PPh3)3].
ligands, (ii) the study of their catalytic activity in transfer
hydrogenation of acetophenone.
Introduction
The design of new ligands for promoting high reactivity and
selectivity in metal-catalyzed synthesis is a field of constant
ongoing research activity. Heteroditopic ligands, bearing phos-
phorus and nitrogen atoms, have attracted particular attention
since they can induce increased selectivity owing to the differ-
ent electronic properties of the two donor atoms. Thus, they
have been successfully used in a great variety of transition
metal catalyzed reactions, among others, hydrosilylations of
=
1
C O bonds, allylic substitutions and Heck reactions. In par-
ticular, many ruthenium(II) complexes bearing bidentate or
tridentate P,N ligands such as phosphinooxazolines and
pyridylphosphines have proven to be efficient catalysts in
transfer hydrogenation of ketones1–3 with high rates and con-
versions. In contrast, only a few catalysts containing analo-
gous imino- and aminophosphine ligands have been used to
date in this type of catalytic process.4
Results and discussion
The new ligands 1c,e and 2d,e have been synthesized following
classical methodologies.6 They have been isolated as air-stable
solids (1c) or oils (1e, 2d,e) in good yields and characterized by
IR and 31P{1H}, 1H and 13C{1H} NMR spectroscopy and
mass spectrometry (see Experimental section for details). The
most significant features are: (i) 31P{1H} NMR: a singlet signal
We have recently reported the synthesis of five- and six-
coordinate ruthenium(II) complexes containing 2-Ph2PC6-
1
at ca. ꢀ14 ppm, (ii) H NMR of 1c,e: a doublet at ca. 9 ppm
1
attributed to the iminic proton, and (iii) H NMR of 2d,e: a
t
H4CH N Bu and 2-Ph2PC6H4CH2NH Bu as chelate ligands.
t
5
=
resonance at ca. 4 ppm corresponding to the CH2N hydrogen
nuclei.
Since these complexes have proved to be very active catalysts
in transfer hydrogenation of acetophenone by propan-2-ol,
we believe it of interest to extend these studies with a series
of imino- and aminophosphine complexes by using analogous
P,N ligands in which the imino and amino substituents intro-
duce different steric and/or electronic features. Thus, in this
paper we report: (i) the synthesis of new ruthenium(II) com-
Synthesis of the iminophosphine complexes [RuCl2(k2-P,N-2-
0
0
=
Ph2PC6H4CH NR)(PPh3)] (R ¼ Ph (3a); 2 ,6 -C6H3Me2 (3b))
3
0
=
and [RuCl2(k -P,N,O-2-Ph2PC6H4CH N-2 -
C6H4OMe)(PPh3)] (3c)
=
plexes containing bidentate 2-Ph2PC6H4CH NR (R ¼ Ph
i
(1a); 20,60-C6H3Me2 (1b); Pr (1d); (S)-CHMeCy (1e)) and 2-
As described for the preparation of the complex [RuCl2(k2-
Ph2PC6H4CH2NHR (R ¼ Ph (2a); iPr (2d); (S)-CHMeCy
t
5
P,N-2-Ph2PC6H4CH N Bu)(PPh3)], the iminophosphines
=
0
0
0
=
(2e)), and the tridentate 2-Ph2PC6H4CH N-2 -C6H4OMe (1c)
=
2-Ph2PC6H4CH NR (R ¼ Ph (1a); 2 ,6 -C6H3Me2 (1b)) react
414
New J. Chem., 2003, 27, 414–420
DOI: 10.1039/b206119h
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2003

View Article Online
Scheme 1
with [RuCl2(PPh3)3], in THF at room temperature, affording
Synthesis of the bis-iminophosphine complexes trans,cis,
=
2
2
i
=
complexes [RuCl2(k -P,N-2-Ph2PC6H4CH NR)(PPh3)] (R ¼
Ph (3a); 20,60-C6H3Me2 (3b)). Similarly, the reaction with
the tridentate iminophosphine 2c gives the complex [RuCl2
cis-[RuCl2(j -P,N-2-Ph2PC6H4CH NR)2] (R ¼ Pr (4d);
(S)-CHMeCy (4e))
The treatment of [RuCl2(PPh3)3] with one equivalent of
2-Ph2PC6H4CH NR (R ¼ iPr (1d); (S)-CHMeCy (1e))
3
0
=
(k -P,N,O-2-Ph2PC6H4CH N-2 -C6H4OMe)(PPh3)]
(3c)
=
(Scheme 1).
does not afford the expected derivatives [RuCl2(k2-P,N-2-
Spectroscopic (IR, Far-IR, 31P{1H}, 1H, and 13C{1H}
NMR) and analytical data confirm the proposed formulations.
Complex 3a has been isolated as a mixture of two non-separ-
able stereoisomers (3a0 and 3a00) as inferred by IR and NMR
spectroscopy. In particular, the Far-IR spectrum shows nRu–Cl
absorptions at 320, and at 292 and 245 cmꢀ1 which are consis-
tent with the presence of trans (3a0) and cis (3a00) dichloride
complexes, respectively (Scheme 1).7 In addition, the 31P{1H}
NMR spectrum exhibits the expected resonances for two AX
spin systems at 87.9 (3a0) and 84.2 (3a00) (Ph2P fragment) and
36.2 (3a0) and 43.9 ppm (3a00) (PPh3 ligand). The small cou-
pling constant values (2JPP ¼ 31.3 (3a0) and 39.6 (3a00) Hz)
are in agreement with the cis-disposition of the two P-donor
groups. In contrast, complexes 3b,c are obtained stereoselec-
tively as the trans dichloride isomers. This is assessed by the
Far-IR spectra which display one single nRu–Cl stretching
absorption at ca. 320 cmꢀ1. The 31P{1H} NMR spectra of
3b,c show an AX spin system at 87.5 (3b) and 69.7 (3c)
(PPh2 group) and 35.7 (3b) and 34.7 (3c) ppm (PPh3 ligand)
with a small coupling constant (2JPP ¼ 33.4 (3b) and 32.6
(3c) Hz) indicative of the cis-arrangement of the two phos-
=
Ph2PC6H4CH NR)(PPh3)], leading instead to an equimolar
mixture of the bis-iminophosphine complexes [RuCl2(k2-P,N-
i
=
2-Ph2PC6H4CH NR)2] (R ¼ Pr (4d); (S)-CHMeCy (4e)) and
the ruthenium precursor. Complexes 4d,e were obtained in a
quantitative yield by the reaction of two equivalents of 1d,e
with [RuCl2(DMSO)4] in refluxing THF (Scheme 1).11 All
attempts to synthesize the bis-iminophosphine complexes
2
[RuCl2(k -P,N-2-Ph2PC6H4CH NR)2]
(R ¼ Ph;
20,60-
=
C6H3Me2 ; 20-C6H4OMe) by treatment of either [RuCl2
(PPh3)3] or [RuCl2(DMSO)4] with a large excess of 1a–c in
refluxing THF failed. Monitoring the reaction by 31P{1H}
NMR only the formation of 3a–c is observed.
Complexes 4d,e have been characterized by elemental ana-
lyses, and spectroscopic methods (IR, Far-IR, 31P{1H}, 1H,
and 13C{1H} NMR spectroscopy). Spectroscopic data show
that only one stereoisomer is obtained among the five possible
for 4d (I–V) and the eight possible for 4e (two diastereoisomers
for each of structures I–III plus IV and V).
1
phorus nuclei. The H NMR spectra of the cis and trans iso-
mers also show remarkable differences. Thus, the iminic
proton resonances of the trans complexes 3a0,b,c show a rela-
tively high 4JPH value (8.8–9.1 Hz) characteristic of a trans dis-
position of the imino group and the PPh3 ligand.8 This
contrasts with the corresponding resonance of the cis complex
3a00 which appears as a singlet in accordance with a cis arrange-
ment of these two groups.5,9 Far-IR and NMR spectroscopic
data of trans complexes 3a0,b,c can be compared with those
2
=
reported for the complex [RuCl2(k -P,N-2-Ph2PC6H4CH
NtBu)(PPh3)]10 which has also been characterized by X-ray
diffraction. In general, the chelate coordination of iminophos-
phine ligands leads to a downfield shift of the phosphorus as
=
well as the CH N carbon resonances with respect to the free
ligands (d 166.5 (3a0), 167.1 (3a00), 172.2 (3b) and 166.1 (3c)
vs. 158.9 (1a), 161.1 (1b) and 159.7 (1c) ppm). In addition,
the downfield shift observed for the OMe signal in the
13C{1H} NMR spectrum of 3c with respect to that of the free
ligand is attributed to its coordination to ruthenium (d 63.3
(3c) vs. 55.8 (1c) ppm). This is also in accord with the highfield
resonance (69.7 ppm) of the phosphorus nucleus trans to the
methoxy group. In contrast, the corresponding resonance in
the five coordinate complexes 3a0, 3a00 and 3b appears at
87.9–84.2 ppm.
On the basis of 31P{1H} and 1H NMR data, stereoisomers I,
III and V can be discarded since the spectra display: (a) only a
single phosphorus resonance (d 48.7 (4d) and 48.8(4e)), (b) the
proton iminic resonance as a filled-in doublet owing to virtual
coupling (d 8.78 (4e) and 8.82 (4d)). This suggests a small 2JPP
value12 consistent with a cis-disposition of the phosphorus
nuclei. In order to determine unambiguously the stereochemis-
try of these compounds an X-ray diffraction study was carried
out on 4d.
New J. Chem., 2003, 27, 414–420
415

View Article Online
Scheme 2
Synthesis of the five-coordinate aminophosphine complexes
[RuCl2(k2-P,N-2-Ph2PC6H4CH2NHR)(PPh3)] (R ¼ Ph (5a);
iPr (5d); (S)-CHMeCy (5e))
Reactions of the aminophosphines 2a,d,e with [RuCl2(PPh3)3],
in THF at room temperature, lead to the formation of the five-
coordinate complexes [RuCl2(k2-P,N-2-Ph2PC6H4CH2NHR)
i
(PPh3)] (R ¼ Ph (5a); Pr (5d); (S)-CHMeCy (5e)) (Scheme 2).
They have been characterized by elemental analyses and spec-
troscopic techniques (IR, Far-IR, and 1H, 31P{1H}, and
13C{1H} NMR spectroscopy) all data being in agreement with
the stoichiometry and a trans RuCl2 arrangement. The most
significant features, which can be compared to those shown
by 3a0, 3b and 3c, are: (i) 31P{1H} NMR: an AX spin system
in the range 72.5–77.6 (PPh2 group) and 40.8–42.0 (PPh3
Fig. 1 ORTEP view of the bis-iminophosphine complex 4d. Thermal
ellipsoids are shown at 30% probability. Hydrogen atoms, except
those of the NCHMe2 fragment (H(41) and H(41a)), are omitted for
clarity.
2
ligand) ppm with a small JPP coupling constant (34.2–38.1
Hz) in accordance with a cis-arrangement of two different P-
donor groups, and (ii) Far-IR: an absorption at ca. 320
cmꢀ1 indicative of a trans arrangement of the chloride atoms.
X-Ray crystal structure of complex 4d
1
An ORTEP drawing is shown in Fig. 1 (stereoisomer IV).
Selected bonds and angles are collected in Table 1. The coordi-
nation geometry around the ruthenium atom can be described
as an octahedron with two chloride atoms occupying the apical
In addition, the H NMR spectra exhibit a NH signal at ca.
4.0–4.5 ppm and the two resonances attributable to the two
diastereotopic CH2N protons in the range 4.0–5.2 ppm. The
inequivalence of the methylenic protons arises from the coor-
dination of the amino group which converts the nitrogen
atom in a stereogenic center. Complex 5e incorporating the
chiral aminophosphine (S)-2-Ph2PC6H4CH2NHCHMeCy
was obtained as a non-separable mixture of two diastereo-
isomers, 5e0 and 5e00, in a 20:80 ratio, arising from the R and
S configurations of the nitrogen atom.
positions [Cl–Ru–Cla ¼ 175.58(4)ꢁ]. The equatorial plane is
i
=
formed by the two bidentate 2-Ph2PC6H4CH N Pr ligands,
displaying a bite angle P–Ru–N of 81.30(7)ꢁ. The two phos-
phorus as well as the two nitrogen atoms are in a cis-disposition
[P–Ru–Pa ¼ 106.10(5); N–Ru–Na ¼ 91.3(1)ꢁ]. The ruthenium
atom is contained in the best least-square base plane. The
Ru–N and C(1)–N imine bond lengths, 2.183(2) and 1.290(4)
0
4
0
˚
A, are similar to those found in [RuCl2(k -P,N,N ,P -Ph2-
Catalytic studies
=
=
PC6H4CH NCH2CH2N CHC6H4PPh2)] [2.094(9), 2.097(6),
13
[RuCl2(k4-P,N,N0,P0-(S,S)-
Ph2PC6H4CH NC6H10N CHC6H4PPh2)] [2.100(5), 2.091(5),
˚
and 1.297(9), 1.285(9) A],
=
˚
and 1.273(8), 1.272(8) A],
The catalytic activity in transfer hydrogenation of acetophe-
none by propan-2-ol of all the novel complexes has been inves-
tigated (Scheme 3). In a typical experiment, NaOH was added
to a solution of the ruthenium(II) catalyst precursor and acet-
=
and [RuCl2(k2-P,N-2-
4a
t
5
˚
=
Ph2PC6H4CH N Bu)(PPh3)] [2.082(6) and 1.255(9) A]. In
contrast with the latter iminophosphine ruthenium complex,
the metallacycles deviate strongly from planarity, probably
to minimize the interactions between the two isopropyl groups.
This is also reflected in the relative disposition of the two
NCHMe2 fragments since the hydrogen atoms, H(41) and
H(41a), are facing each other.
i
ophenone (0.1 M) in PrOH (ketone:Ru:base ¼ 500:1:24) at
refluxing temperature, the reaction being monitored by gas
chromatography. Selected results are collected in Table 2.
For comparative purposes, the catalytic activity of complexes
2
t
2
=
[RuCl2(k -P,N-2-Ph2PC6H4CH N Bu)(PPh3)] and [RuCl2(k -
P,N-2-Ph2PC6H4CH2NHtBu)(PPh3)] previously reported by
us5 and that of [RuCl2(PPh3)3] used by Ba¨ckvall,14 have also
been examined under the same conditions.
All the complexes 3a–c, 4d,e and 5a,d,e are more active cat-
alysts than the precursor [RuCl2(PPh3)3] (entries 1–10 vs. entry
11), and afford almost quantitative yields of 1-phenylethanol
within 4 hours. The highest rate is observed for 3a (as a miꢀx1-
ture of 3a0 and 3a00), the turnover frequency being 5220 h
at 50% of conversion (entry 2). The chiral six coordinate com-
plex 4e leads to a moderate enantiomeric excess (44%; entry 6).
In contrast, no chiral induction is observed when the mixture
ꢁ
˚
Table 1 Selected bond lengths (A) and angles ( ) for 4d
Bond lengths
Ru–N
2.183(2)
N–C(1)
1.290(4)
1.504(4)
Ru–P
Ru–Cl
2.2957(9) N–C(41)
2.4164(9)
Bond angles
N–Ru–P
N–Ru–Pa
81.30(7)
172.54(7)
106.10(5)
90.09(7)
N–Ru–Na
P–Ru–Cl
P–Ru–Cla
Cl–Ru–Cla
91.3(1)
94.23(3)
88.43(3)
175.58(4)
P–Ru–Pa
N–Ru–Cl
Torsion angles
Ru–P–C(31)–C(36)
P–C(31)–C(36)–C(1)
43.7(2)
1.8(4)
C(36)–C(1)–N–Ru ꢀ11.1(5)
P–Ru–N–C(1)
N–Ru–P–C(31)
45.4(3)
ꢀ52.0(1)
C(31)–C(36)–C(1)–N ꢀ24.6(5)
Scheme 3
416
New J. Chem., 2003, 27, 414–420

View Article Online
Table 2 Transfer hydrogenation of acetophenonea
Yield (%)b
Time/h
TOF50
ee (%)d
c
Entry
Catalyst
=
Complexes [RuCl2(PPh3)(2-Ph2PC6H4CH NR)]
1
2
3
4
R ¼ tBu5
97
98
98
98
2
1
3
4
1650
5220
590
—
—
—
—
R ¼ Ph, 3a
R ¼ 20,60-C6H3Me2 , 3b
R ¼ 20-C6H4OMe, 3c
730
=
Complexes [RuCl2(2-Ph2PC6H4CH NR)2]
5
R ¼ iPr, 4d
97
97
1
1
1030
820
—
44 (R)
6
Complexes [RuCl2(PPh3)(2-Ph2PC6H4CH2NHR)]
R ¼ (S)-CHMeCy, 4e
7
R ¼ tBu5
97
96
96
98
91
2
2
2
1
5
1610
1680
1040
2500
220
—
—
—
0
8
R ¼ Ph, 5a
9
R ¼ iPr, 5d
10
11
R ¼ (S)-CHMeCy, 5e
[RuCl2(PPh3)3]
—
a
Conditions: reactions were carried out in a Schlenk tube fitted with a condenser at 82 ꢁC using 50 mL of propan-2-ol, 5 mmol of acetophenone,
0.2 mol% of catalyst precursor and 4.8 mol% of NaOH. b Yield of 1-phenylethanol, GC determined. c Turnover frequency ¼ ((mol product/mol
catalyst)/time) at 50% conversion, in hꢀ1
of the sign of optical rotation.
.
Enantiomeric excess, GC determined. Absolute configuration in parenthesis, determined on the basis
d
of diastereoisomers of the five-coordinate complex 5e is used
(entry 10) even at temperatures lower than 82 ꢁC.
the related iminophosphines. The steric properties also seem to
govern the stereoselectivity of the five coordinate iminopho-
sphine complexes 3a,b since, for the bulkier xylyl group, the
trans stereoisomer vs. the mixture of cis and trans for the phe-
nyl substituted iminophosphine, is obtained.
All the complexes 3–5 are efficient catalysts in transfer
hydrogenation of ketones. The catalytic activity can be com-
pared to that observed for analogous ruthenium(II) complexes
bearing other chelating P,N ligands.3 It is interesting to note
The evolution of the conversion as a function of the reaction
time was investigated. In contrast with 16-electron complexes
3a,b and 5a,d,e, the saturated derivatives [RuCl2(k3-P,N,O-2-
2
0
i
=
Ph2PC6H4CH N-2 -C6H4OMe)(PPh3)] (3c), [RuCl2(k -P,N-
2-Ph2PC6H4CH N Pr)2] (4d) and [RuCl2(k2-P,N-(S)-2-
=
Ph2PC6H4CH NCHMeCy)2] (4e) present, before the fast reac-
=
tion of acetophenone, an induction period (of 5, 20 and 30 min
respectively). In addition, during the first thirty minutes, the
enantiomeric excess observed for 4e increases from 16 to
46% and then remains almost constant. This is indicative of
an evolution of the active species. In order to find out how
the chiral catalyst 4e changes as a function of time, the follow-
ing experiments were carried out: (i) the catalyst and NaOH
were refluxed for 30 min, and then acetophenone was added,
and (ii) the catalyst, NaOH and a small quantity of acetophe-
none (Ru:acetophenone ¼ 1:10) were refluxed for 30 min, and
then the rest of acetophenone was added, (iii) the catalyst,
NaOH and a small quantity of racemic 1-phenylethanol
(Ru:1-phenylethanol ¼ 1:10) were refluxed for 30 min, and
then acetophenone was added. In the two former cases the
induction time, the conversion and the enantiomeric excess
are not affected. In the latter case no induction period is
observed but the enantiomeric excess drops dramatically to
2%. This seems to indicate that the initial active species formed
from the precursor and the base reacts with the 1-phenyletha-
nol. When the 1-phenylethanol is enantiomerically enriched
the enantiomeric excess increases with the conversion. A simi-
lar effect has been described previously in hydrogen transfer
reaction of isopropyl phenyl ketone catalyzed by [Ir(COD)Cl]2
associated with a salen type ligand.15
that the mixture of the trans and cis isomers of complex
2
[RuCl2(k -P,N-2-Ph2PC6H4CH NPh)(PPh3)] (3a0 and 3a00
=
respectively) has been found to be by far the most efficient cat-
alyst precursor. Since similar five-coordinate cis-dichloride
complexes [RuCl2(PPh3)(oxazolinylferrocenylphosphine)] have
proved to be particularly active in transfer hydrogenation of
acetophenone3c,d,f we propose that the increased catalytic
activity observed for 3a is probably due to the presence of
the cis-isomer. However, the catalytic results for 3–5 do not
allow us to determine clearly the influence of the steric and
electronic properties of the different ligands on the catalytic
activity.
Experimental
General
The manipulations were performed under an atmosphere of
dry nitrogen using vacuum-line and standard Schlenk techni-
ques. 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],16 [RuCl2(DMSO)4],17 2-
18
19
Ph2PC6H4CH NR (R ¼ Ph, -20,60-C6H3Me2 , iPr20) and
2-Ph2PC6H4CH2NHPh21 were prepared following the methods
previously reported. Gas chromatographic measurements were
made on a Hewlett Packard HP6890 equipment. A HP-INNO-
WAX cross-linked polyethyleneglycol (30 m, 250 mm) or a
Supelco Beta-DexTM 120 (30 m, 250 mm) columns were used.
Infrared spectra were recorded on a Perkin-Elmer 1720-XFT
or a Perkin Elmer FT-IR 1000 spectrometer. The C, H and
N analyses were carried out with a Perkin-Elmer 2400 micro-
analyzer. NMR spectra were recorded on Bruker AC300 or
300DPX instruments at 300 (1H), 121.5 (31P) or 75.4 MHz
(13C) using SiMe4 or 85% H3PO4 as standards. DEPT experi-
ments have been carried out for all the compounds. Coupling
=
Conclusions
In this work new five (3a–b) and six coordinate (3c,4c–d) imi-
nophosphine ruthenium(II) complexes are reported. The stoi-
chiometry seems to depend on the steric hindrance of the
ligands. Thus the bulky iminophosphines 1a–c bearing iminic
aryl groups give rise only to the five coordinate complexes
(3a–b), while the ligands 1d,e, bearing a -CHRR0 substituent
on the nitrogen, lead to the six-coordinate bis-iminophosphine
derivatives (4d,e). In contrast, aminophosphines 2a,d,e only
form five coordinate 16-electron complexes (5a,d,e) reflecting
the higher steric hindrance of these ligands in comparison with
New J. Chem., 2003, 27, 414–420
417

View Article Online
3
constants J are given in Hertz. Abbreviations used: FIR,
Far-infrared; Ar, aromatic; s, singlet; d, doublet; df , filled-in
doublet; sept, septuplet; m, multiplet. Numbering used for
the ligands:
2 H, CH2N), 2.70 (sept, 1 H, JHH ¼ 6.2, CHMe2), 0.93 (d, 6
3
H, JHH ¼ 6.2, CHMe2), the NH proton is not observed.
13C{1H} NMR, CDCl3 , d: 144.2 (d, JPC ¼ 23.5, C-2), 136.5
1
1
2
(d, JPC ¼ 10.2, C-i), 137.7, (d, JPC ¼ 13.4, C-1), 133.8 (d,
2JPC ¼ 20.3, C-o), 133.6 (s, C-4, 5 or 6), 129.6 (d, JPC ¼ 5.1,
2
5.1, C-3), 129.0 (s, C-4, 5 or 6), 128.7 (s, C-p), 128.5 (d,
3JPC ¼ 7.0, C-m), 127.3 (s, C-4, 5 or 6), 50.0 (d, JPC ¼ 21.0,
3
CH2N), 48.0 (s, CHMe2), 22.4 (s, CHMe2). IR (Neat, cmꢀ1),
nN–H : 3312. HRMS m/z calc. for C22H24NP (found):
M+ ¼ 333.16463 (333.16471).
Synthesis of (S)-2-Ph2PC6H4CH2NHCHMeCy, 2e. Follow-
ing the same procedure 2e was obtained as a pale yellow oil
=
using (S)-2-Ph2PC6H4CH NCHMeCy (0.200 g, 0.50 mmol)
and NaBH4 (0.081 g, 2.14 mmol). Yield: 0.193 g (96%).
31P{1H} NMR, CDCl3 , d:ꢀ15.7 (s). 1H NMR, CDCl3 , d:
7.55–7.15 (m, 13 H, ArH), 6.92 (m, 1 H, H-3), 4.05 (part A
2
Synthesis and product characterization
of AB system, 1 H, JHH ¼ 19.7, NCH2), 3.95 (part B of AB
2
system, 1 H, JHH ¼ 19.7, NCH2), 2.42 (m, 1 H, CHMe),
0
=
2-Ph2PC6H4CH N-2 -C6H4OMe, 1c.
A solution of 2-
1.80–0.78 (m, 11 H, Cy), 0.93 (d, 3 H, 3JHH ¼ 6.3 Hz, CHMe),
(diphenylphosphino)benzaldehyde (0.248 g, 0.85 mmol) and
2-anisidine (0.105 g, 0.85 mmol) in a mixture of methanol
(40 mL) and dichloromethane (20 mL) was stirred overnight
at room temperature. After evaporation to dryness, the residue
was washed twice with 5 mL of a mixture of hexane–diethyl
ether (9:1) to afford a pale yellow solid. Yield: 0.321 g (96%).
Found (calc. for C26H22NOP): C, 79.03 (78.97); H, 5.74
the NH proton is not observed. 13C{1H} NMR, CDCl3 , d:
1
1
145.1 (d, JPC ¼ 24.1, C-2), 136.8 (d, JPC ¼ 9.9, C-i), 135.6
2
2
(d, JPC ¼ 12.8, C-1), 133.8 (d, JPC ¼ 19.2, C-o), 133.7 (d,
2JPC ¼ 19.2, C-o), 133.6 (s, C-4, 5 or 6), 129.5 (d, JPC ¼ 5.7,
2
4
5.7, C-3), 129.0 (s, C-4, 5 or 6), 128.6 (d, JPC ¼ 2.1, C-p),
3
128.5 (d, JPC ¼ 7.1, C-m), 127.1 (s, C-4, 5 or 6), 57.0 (s,
3
NCHMe), 50.2 (d, JPC ¼ 21.3, CH2N), 42.6 (s, CH, Cy),
(5.61); N, 3.49 (3.54)%. 31P{1H} NMR, CDCl3 , d: ꢀ13.9 (s).
4
29.7, 27.6, 26.7, 26.6 and 26.4 (all s, CH, Cy), 16.3 (s, Me).
: 3315. HRMS m/z calc. for
1H NMR, CDCl3 , d: 9.18 (d, 1 H, JPH ¼ 5.4 Hz, CH N),
=
IR (Nujol, cmꢀ1), nN–H
8.33 (m, 1 H, H-6), 7.72–6.60 (m, 17 H, ArH), 3.78 (s, 3 H,
3
C27H32NP (found): M+ ¼ 401.22722 (401.22729).
OMe). 13C{1H} NMR, CDCl3 , d: 159.7 (d, JPC ¼ 25.6,
2
0
0
=
CH N), 152.3 (s, C-2 ), 141.4 (s, C-1 ), 139.5 (d, JPC ¼ 16.9,
2
Synthesis of [RuCl2(j -P,N-2-Ph2PC6H4CH NPh)(PPh3)],
3a0 and 3a00. A solution of [RuCl2(PPh3)3] (0.200 g, 0.21 mmol)
=
and 2-Ph2PC6H4CH NPh (0.116 g, 0.32 mmol) in 30 mL of
=
1
1
16.9, C-1), 138.4 (d, JPC ¼ 19.8, C-2), 136.2 (d, JPC ¼ 9.9,
2
C-i), 134.1 (d, JPC ¼ 19.8, C-o), 133.4 (s, C-4, 5 or 6), 130.9
(s, C-4, 5 or 6), 129.0 (s, C-4, 5 or 6), 128.9 (s, C-p), 128.7
3
2
THF was stirred for 2 hours at room temperature. After eva-
poration to dryness, the resulting residue was washed 3 times
with 10 mL of a mixture of hexane and diethyl ether (1:1) to
afford a red solid. A mixture of two non-separable isomers,
3a0 and 3a00, is obtained in a 60:40 ratio. Yield: 0.151 g
(90%). Found (calc. for C43H35Cl2NP2Ru): C, 64.55 (64.58);
(d, JPC ¼ 7.0, C-m), 127.8 (d, JPC ¼ 4.1, C-3), 126.7, 120.9,
120.7 and 111.5 (all s, C-30, 40, 50 and 60), 55.8 (s, OMe). IR
(Nujol, cmꢀ1), nC N : 1607.
=
=
Synthesis of (S)-2-Ph2PC6H4CH NCHMeCy, 1e. Following
H, 4.38 (4.41); N, 1.73 (1.75). P{1H} NMR, CDCl3 , d: 3a0
31
the same procedure 1e was prepared as a colorless oil, using
0.272 g (0.94 mmol) of 2-(diphenylphosphino)benzaldehyde
and 0.2 mL (1.35 mmol) of (S)-(+)-cyclohexylethylamine.
2
2
87.9 (d, JPP ¼ 31.3, PPh2), 36.2 (d, JPP ¼ 31.3, PPh3); 3a00
84.2 (d, JPP ¼ 39.6, PPh2), 43.9 (d, JPP ¼ 39.6, PPh3). 1H
2
2
Yield: 0.365 g (97%). 31P{1H} NMR, CDCl3 , d: ꢀ12.9 (s).
4
NMR, CDCl3 , d: 3a0 9.00 (d, 1 H, JPH ¼ 9.1, CH ¼ N),
4
1H NMR, CDCl3 , d: 8.81 (d, 1 H, JPH ¼ 4.8 Hz, CH N),
=
8.07–6.67 (m, 34 H, ArH); 3a00 8.72 (s, 1 H, CH ¼ N), 8.07–
6.67 (m, 34 H, ArH). C{1H} NMR, CDCl3 , d: 3a0 166.5
13
7.99 (m, 1 H, H-6), 7.60–7.14 (m, 12 H, ArH), 6.86 (m, 1 H,
H-3), 2.89 (m, 1 H, CHMe), 1.70–0.60 (m, 11 H, Cy), 1.03
3
0
=
(d, JPC ¼ 4.5, CH N), 150.9 (s, C-1 ), 136.7–123.1 (m, Ar);
3
(d, 3 H, JHH ¼ 6.3 Hz, CHMe). 13C{1H} NMR, CDCl3 , d:
0
3
3a00 167.1 (d, JPC ¼ 6.0, CH N), 151.9 (s, C-1 ), 136.7–123.1
=
3
2
(m, aromatic). IR and FIR (Nujol, cmꢀ1), nC N : 1608, 1588;
157.3 (d, JPC ¼ 21.2 Hz, CH ¼ N), 139.7 (d, JPC ¼ 16.6
=
1
1
Hz, C-1), 137.1 (d, JPC ¼ 18.9 Hz, C-2), 136.5 (d, JPC ¼ 9.8
n
Cl–Ru–Cl : 323, 292, 245.
1
9.8 Hz, C-i), 136.4 (d, JPC ¼ 9.1 Hz, C-i), 134.2 (d,
2
2JPC ¼ 20.4 Hz, C-o), 134.1 (d, JPC ¼ 20.4 Hz, C-o), 132.8
0
0
2
Synthesis of [RuCl2(j -P,N-2-Ph2PC6H4CH N-2 ,6 -
C6H3Me2)(PPh3)], 3b. Following the same procedure 3b was
prepared as a purple solid using [RuCl2(PPh3)3] (0.200 g,
=
(s, C-4, 5, or 6), 129.8 (s, C-4, 5 or 6), 128.8 (s, 2 C, C-p),
3
128.5 (d, 4 C, JPC ¼ 6.8 Hz, C-m), 128.3 (s, C-4, 5 or 6),
2
127.7 (d, JPC ¼ 4.5 Hz, C-3), 71.9 (s, NCH), 43.4 (s, CH of
0
0
=
0.21 mmol), 2-Ph2PC6H4CH N-2 ,6 -C6H3Me2 (0.116 g, 0.29
mmol) and 20 mL of THF. Yield: 0.132 g (76%). Found (calc.
for C45H39Cl2NP2Ru): C, 65.15 (65.30); H, 4.74 (4.75); N, 1.72
(1.69). 31P{1H} NMR, CD2Cl2 , d: 87.5 (d, 2JPP ¼ 33.4, PPh2),
35.7 (d, 2JPP ¼ 33.4, PPh3). 1H NMR, CD2Cl2 , d: 8.80 (d, 1 H,
4JPH ¼ 8.8, CH ¼ N), 7.76–6.66 (m, 32 H, ArH), 6.66 (dd, 1
Cy), 29.6, 26.5, 26.3 and 26.2 (all s, CH2 of Cy), 19.7 (s,
Me). IR (Nujol, cmꢀ1), nC N : 1638. HRMS m/z calc. for
=
C27H30NP (found): M+ ¼ 399.21120 (399.21139).
Synthesis of 2-Ph2PC6H4CH2NHiPr, 2d. A solution of 2-
i
3
3
=
Ph2PC6H4CH N Pr (0.410 g, 1.24 mmol) in 30 mL of metha-
H, JPH ¼ 10.5, JHH ¼ 7.7, H-3), 1.86 (s,
6
H, Me).
=
3
nol was treated by NaBH4 (0.180 g, 4.76 mmol) at 0 ꢁC. After
stirring 15 min the reaction was quenched with aqueous NaOH
(5 mL, 1 M). The organic layer was extracted with dichloro-
methane (3 ꢂ 15 mL) and the combined phases were dried over
MgSO4 . The solvents were removed to afford a pale yellow oil
which was used without further purification. Yield: 0.390 g
(94%). 31P{1H} NMR, CDCl3 , d: ꢀ15.6 (s). 1H NMR, CDCl3 ,
d: 7.48 (m, 1 H, H-6), 7.36–7.14 (m, 12 H, ArH), 6.89 (ddd,
3JHH ¼ 7.3, 3JPH ¼ 4.6, 4JHH ¼ 1.1, 1 H, H-3), 3.99 (s broad,
13C{1H} NMR, CD2Cl2 , d: 172.2 (d, JPC ¼ 4.1, CH N),
153.2 (s, C-10), 137.3 (d, 1JPC ¼ 12.2, C-2), 134.9 (d, JPC ¼ 9.9,
1
9.9, C-o, PPh3), 133.4 (d, JPC ¼ 55.3, C-i, PPh3), 125.7 (s,
C-40), 137.4–126.7 (m, Ar), 20.4 (s, Me). IR and FIR (Nujol,
cmꢀ1), nC N : 1598; nCl–Ru–Cl : 318.
=
3
[RuCl2(j -P,N,O-2-Ph2PC6H4CH N-2 -
0
=
Synthesis
C6H4OMe)(PPh3)], 3c. Following the same procedure 3c was
prepared as a red solid, using [RuCl2(PPh3)3] (0.181 g, 0.19
of
418
New J. Chem., 2003, 27, 414–420

View Article Online
0
=
mmol) and 2-Ph2PC6H4CH N-2 -C6H4OMe (0.090 g, 0.23
mmol) in 40 mL of THF. Yield: 0.139 g (88%). Found (calc.
for C44H37Cl2NOP2Ru): C, 63.81 (63.70); H, 4.48 (4.50); N,
JPC ¼ 9.0, C-o or -m, PPh3), 127.4 (d, JPC ¼ 10.2, C-o or
-m, PPh2), 125.5 (s, C-40), 121.3 (s, C-20,60), 56.6 (d, JPC ¼ 5.6,
5.6, CH2N). IR and FIR (Nujol, cmꢀ1), nN–H : 3225; nCl–Ru–Cl
319.
:
1.67 (1.70). 31P{1H} NMR, CD2Cl2 , d: 69.7 (d, JPP ¼ 32.6,
2
PPh2), 34.7 (d, JPP ¼ 32.6, PPh3). 1H NMR, CD2Cl2 , d:
2
4
9.03 (d, 1 H, JPH ¼ 8.8, CH ¼ N), 7.77–6.72 (m, 33 H,
ArH), 3.41(s, 3 H, OMe). 13C{1H} NMR, CD2Cl2 , d: 166.1
Synthesis of [RuCl2(j2-P,N-2-Ph2PC6H4CH2NHiPr)(PPh3)],
5d. Following the same procedure [RuCl2(k2-P,N-2-
Ph2PC6H4CH2NHiPr)(PPh3)] was prepared as a green solid,
using [RuCl2(PPh3)3] (0.500 g, 0.52 mmol) and 2-
Ph2PC6H4CH2NHiPr (0.210 g, 0.63 mmol) in 30 mL of
3
0
0
=
(d, JPC ¼ 3.2, CH N), 156.1 (s, C-2 ), 145.7 (s, C-1 ), 137.7
2
2
(d, JPC ¼ 12.7, C-1), 137.5 (d, JPC ¼ 8.3, C-3), 127.7 (d,
3JPC ¼ 8.9, C-m, PPh3), 127.5 (d, JPC ¼ 10.2, C-m, PPh2),
3
124.2, 119.2 and 117.6 (all s, 3 C of C-30, 40, 50 and 60),
135.8–128.9 (m, Ar), 63.3 (s, OMe). IR and FIR (Nujol,
THF. Yield: 0.375
C40H39Cl2NP2Ru): C, 62.63 (62.58); H, 5.10 (5.12); N, 1.85
g
(94%). Found (calc. for
cmꢀ1), nC N : 1608; nCl–Ru–Cl : 319.
=
2
(1.82)%. 31P{1H} NMR, CDCl3 , d: 74.1 (d, JPP ¼ 37.3,
2
PPh2), 41.6 (d, JPP ¼ 37.3, PPh3). 1H NMR, CDCl3 , d:
2
Synthesis of trans,cis,cis-[RuCl2(j -P,N-2-Ph2PC6H4CH
=
2
7.62–6.67 (m, 29 H, ArH), 4.51 (ddd, 1 H, JHH ¼ 11.3,
NiPr)2], 4d. A suspension of [RuCl2(DMSO)4] (0.500 g, 1.03
4JPH ¼ 11.3, J ¼ 2.0, CH2N), 4.01 (m, 2 H, CH2N and NH),
i
mmol) and 2-Ph2PC6H4CH N Pr (0.821 g, 2.48 mmol) in 60
=
3
3.86 (m, 1 H, CHMe2), 1.40 (d, 3 H, JHH ¼ 6.3, CHMe),
mL of THF was refluxed for 6 hours. The resulting red solu-
tion was filtered through kieselguhr and the filtrate was evapo-
rated to dryness. The residue was washed 3 times with 10 mL
of a mixture of hexane–diethyl ether (4:1) to afford a red-
brownish solid. Yield: 0.645 g (75%). Found (calc. for
C44H44Cl2N2P2Ru): C, 63.27 (63.31); H, 5.42 (5.31); N, 3.27
3
0.89 (d, 3 H, JHH ¼ 6.2, CHMe). 13C{1H} NMR, CDCl3 ,
2
2
d: 140.2 (d, JPC ¼ 12.7, C-1), 134.7 (d, JPC ¼ 10.2, C-o,
1
2
PPh3), 134.6 (d, JPC ¼ 39.4, C-i, PPh3), 134.5 (d, JPC ¼ 9.5,
2
9.5, C-o, PPh2), 134.4 (d, JPC ¼ 10.2, C-o, PPh2), 129.9 (d,
4JPC ¼ 2.5, C-p, PPh2), 129.7 (d, JPC ¼ 2.5, C-p, PPh2),
4
4
3
129.1 (d, JPC ¼ 1.9, C-p, PPh3), 127.5 (d, JPC ¼ 9.5, C-m,
(3.36)%. 31P{1H} NMR, CDCl3 , d: 48.7 (s). 1H NMR, CDCl3 ,
3
PPh3), 127.5 (d, JPC ¼ 11.0, C-m, PPh2), 126.9 (d,
4
=
d: 8.78 (df , 2 H, JPH ¼ 6.5, CH N), 7.71–6.31 (m, 28 H,
3JPC ¼ 11.0, C-m, PPh2), 131.9–129.0 (m, Ar), 53.9 (dd,
3
ArH), 4.57 (m, 2 H, CHMe2), 1.51 (d, 6 H, JHH ¼ 6.5, Me),
3JPC ¼ 7.6, JPC ¼ 1.9, CH2N), 51.3 (s, CHMe2), 23.9 (d,
3
0.73 (d, 6 H, JHH ¼ 6.0, Me). 13C{1H} NMR, CD2Cl2 , d:
3
4JPC ¼ 3.2, CHMe), 21.5 (d, JPC ¼ 1.9, CHMe). IR and
4
=
167.4 (broad s, CH N), 139.5–127.2 (m, Ar), 61.7 (s, CHMe2),
FIR (Nujol, cmꢀ1), nN–H : 3197; nCl–Ru–Cl : 317.
28.3 (s, CHMe), 24.1 (s, CHMe). IR and FIR (Nujol, cmꢀ1),
nC N : 1616; nCl–Ru–Cl : 341.
=
Synthesis of [RuCl2(j2-P,N-(S)-2-Ph2PC6H4CH2NHCHMe-
Cy)(PPh3)], 5e0 and 5e00. Prepared following the same proce-
dure as a green solid, using RuCl2(PPh3)3 (0.420 g, 0.44
mmol) and (S)-2-Ph2PC6H4CH2NHCHMeCy (0.210 g, 0.52
mmol) in 30 mL of THF. Compound 5e is obtained as a mix-
ture of two non-separable diastereoisomers, 5e0 and 5e00, in a
2
Synthesis of trans,cis,cis-[RuCl2(j -P,N-(S)-2-Ph2PC6H4CH
NCHMeCy)2], 4e. Following the same procedure 4e was pre-
pared as a red-brownish solid using [RuCl2(DMSO)4] (0.480
=
=
g, 0.99 mmol), (S)-2-Ph2PC6H4CH NCHMeCy (0.950 g,
2.38 mmol) and 60 mL of THF. Yield: 0.640 g (67%). Found
(calc. for C54H60Cl2N2P2Ru): C, 66.73 (66.80); H, 6.31
20:80 ratio. Yield: 0.384 g (90%). Found (calc. for
C44H47Cl2NP2Ru): C, 64.09 (64.15); H, 5.82 (5.75); N, 1.71
(6.23); N, 2.93 (2.88)%. 31P{1H} NMR, CDCl3 , d: 48.8 (s).
4
1H NMR, CDCl3 , d: 8.82 (df , 2 H, JPH ¼ 6.7, CH N),
=
31
2
(1.70)%. P{1H} NMR, CDCl3 , d: 5e0 72.8 (d, JPP ¼ 37.3,
7.71–6.31 (m, 28 H, ArH), 2.42 (m, 1 H, CHMe), 1.80–0.78
2
2
PPh2), 42.0 (d, JPP ¼ 37.3, PPh3), 5e00 72.5 (d, JPP ¼ 34.2,
3
(m, 11 H, Cy), 0.93 (d, 3 H, JHH ¼ 6.3 Hz, CHMe).
2
1
PPh2), 41.7 (d, JPP ¼ 34.2, PPh3). H NMR, CDCl3 , d: 5e0
13
1
=
C{ H} NMR, CD2Cl2 , d: 167.0 (s, CH N), 140.2–127.5
(m, Ar), 69.4 (s, CHN), 40.9 (s, CH, Cy), 31.2, 26.7, 26.6,
3
7.62–6.65 (m, 29 H, ArH), 4.54 (dd, 1 H, JHH ¼ 10.4,
2JHH ¼ 10.4, CH2N), 4.43 (ddd,
1
H, JHH ¼ 10.4,
3
25.6 and 23.7 (all s, CH2 , Cy), 14.9 (s, Me). IR and FIR
(Nujol, cmꢀ1), nC N : 1616.; nCl–Ru–Cl : 335.
3JHH ¼ 10.4, JPH ¼ 3.9, NH), 4.02 (dd, 1 H, JHH ¼ 10.4,
3
2
4JPH ¼ 4.3, CH2N), 3.66 (m, 1 H, CHMe), 2.10–0.87 (m, 11
=
3
H, Cy), 0.68 (d, 3 H, JHH ¼ 6.8, CHMe). 5e00 7.62–6.65 (m,
Synthesis of [RuCl2(j2-P,N-2-Ph2PC6H4CH2NHPh)(PPh3)],
5a. A solution of [RuCl2(PPh3)3] (0.228 g, 0.24 mmol) and 2-
Ph2PC6H4CH2NHPh (0.105 g, 0.29 mmol) in 30 mL of THF
was stirred at room temperature for 2 hours. After evaporation
to dryness, the resulting residue was washed 3 times with 10
mL of a mixture of hexane and diethyl ether (1:1) to afford a
29 H, ArH), 4.28 (m, 2 H, CH2N and NH), 4.08 (m, 1 H,
CH2N), 3.87 (m, 1 H, CHMe), 2.10–0.87 (m, 11 H, Cy), 1.31
3
(d, 3 H, JHH ¼ 6.3, Me). Attribution confirmed by 1H–1H
Cosy. C{1H} NMR, CDCl3 , d: 5e0 140.7–126.9 (m, Ar),
13
3
59.8 (s, NCH), 53.1 (d, JPC ¼ 5.8, NCH2), 38.2 (s, CH, Cy),
30.3, 26.8, 26.6, 26.3 and 25.2 (all s, CH2 , Cy), 15.9 (d,
4JPC ¼ 4.6, Me). 5e00 139.5–127.4 (m, Ar), 58.4 (s, NCH),
green solid. Yield: 0.182
g (95%). Found (calc. for
C43H37Cl2NP2Ru): C, 64.03 (64.42); H, 4.87 (4.65); N, 1.80
3
52.4 (d, JPC ¼ 5.8, NCH2), 43.8 (s, CH, Cy), 31.5, 29.9,
2
(1.75)%. 31P{1H} NMR, CDCl3 , d: 77.6 (d, JPP ¼ 38.1,
4
26.1, 25.6 and 25.3 (all s, CH2 , Cy), 14.7 (d, JPC ¼ 2.3,
2
PPh2), 40.8 (d, JPP ¼ 38.1, PPh3). 1H NMR, CDCl3 , d:
Me). IR and FIR (Nujol, cmꢀ1), nN–H : 3209; nRu–Cl : 320, 315.
7.67–6.35 (m, 34 H, ArH), 5.19 (dd,
1
H, J ¼ 11.5,
3
2JHH ¼ 11.5, CH2N), 4.50* (broad d, 1 H, JHH ¼ 3.8, NH),
2
3
4.32 (dd, 1 H, JHH ¼ 11.5, JHH ¼ 3.8, CH2N).* This signal
disappears when D2O is added. 13C{1H} NMR, CD2Cl2 , d:
General procedure for catalytic transfer hydrogenation
of acetophenone
1
146.9 (s, C-10), 140.1 (d, JPC ¼ 13.6, C-2), 135.0 (d,
1JPC ¼ 41.8, C-i, PPh3), 135.1 (d, JPC ¼ 10.2, C-o or -m,
PPh2), 134.7 (d, JPC ¼ 10.2, C-o or -m, PPh2), 134.6 (d,
Under an inert atmosphere, acetophenone (5 mmol), the ruthe-
nium catalyst precursor (0.01 mmol, 0.2 mol%), and 45 mL of
propan-2-ol were introduced in a Schlenk tube fitted with a
condenser and heated at 82 ꢁC for 15 min. Then NaOH was
added (5 mL of a 0.048 M solution in propan-2-ol, 4.8
mol%) and the reaction was monitored by gas chromatogra-
phy. 1-Phenylethanol and acetone were the only products
detected in all cases.
1
JPC ¼ 10.2, C-o or -m, PPh3), 133.5 (d, JPC ¼ 47.5, C-i,
PPh2), 132.5–132.1 (m, Ar), 132.0 (d, JPC ¼ 3.7, C-3,4,5 or
1
6), 131.4 (d, JPC ¼ 2.4, C-3,4,5 or 6), 130.8 (d, JPC ¼ 54.3,
4
C-i, PPh2), 130.6 (d, JPC ¼ 2.4, C-p, PPh2), 130.3 (d,
4JPC ¼ 2.4, C-p, PPh2), 129.8 (s, C-p, PPh3), 129.0 (s, C-
30,50), 128.2 (d, JPC ¼ 10.2, C-o or -m, PPh2), 128.1 (d,
New J. Chem., 2003, 27, 414–420
419

View Article Online
A. Tiripicchio, Inorg. Chem., 2000, 39, 4468; (i) P. Braunstein,
X-ray diffraction study of 4d
F. Naud, A. Pfaltz and S. J. Rettig, Organometallics, 2000, 19,
2676; ( j) P. Braunstein, F. Naud and S. J. Rettig, New J. Chem.,
2001, 25, 32.
2
=
Suitable single crystals of [RuCl2(k -P,N-2-Ph2PC6H4CH
NiPr)2]ꢃtoluene for X-ray diffraction analyses were obtained
by slow diffusion of hexane into a concentrated solution of
4d in toluene. Data were collected on a Nonius CAD-4 single
crystal diffractometer. The crystal data and structure refine-
ment are: C51H52Cl2N2P2Ru, M ¼ 926.26, monoclinic,
4
(a) J.-X. Gao, T. Ikariya and R. Noyori, Organometallics, 1996,
15, 1087; (b) Y. Jiang, Q. Jiang, G. Zhu and X. Zhang, Tetrahe-
dron Lett., 1997, 38, 6565; (c) J.-X. Gao, X.-D. Yi, P.-P. Xu,
C.-L. Tang, H.-L. Wan and T. Ikariya, J. Organomet. Chem.,
1999, 592, 290; (d ) A. M. Maj, K. M. Pietrusiewicz, I. Suisse,
F. Agbossou and A. Mortreux, J. Organomet. Chem., 2001, 626,
157; (e) C. Standfest-Hauser, C. Slugovc, K. Mereiter, R. Schmid,
K. Kirchner, L. Xiao and W. Weissensteiner, J. Chem. Soc., Dal-
ton Trans., 2001, 2989.
´
P. Crochet, J. Gimeno, S. Garcıa-Granda and J. Borge, Organo-
metallics, 2001, 20, 4369.
(a) H. Brunner and A. F. M. M. Rahman, Chem. Ber., 1984, 117,
710; (b) S. Antonaroli and B. Crociani, J. Organomet. Chem.,
1998, 560, 137.
˚
a ¼ 14.816(3), b ¼ 17.296(4), c ¼ 18.660(5) A, b ¼
3
ꢁ
˚
106.21(3) , U ¼ 4591(2) A , T ¼ 293 K, space group C2/c,
Z ¼ 4, l(Mo-Ka) ¼ 0.564 mmꢀ1. 4952 reflections measured,
4499 unique (Rint ¼ 0.041) which were used in all calculations.
The final wR(F2) was 0.117 (all data).
5
6
CCDC reference number 199894. See http://www.rsc.org/
suppdata/nj/b2/b206119h/ for crystallographic data in CIF
or other electronic format.
7
8
9
(a) M. S. Lupin and B. L. Shaw, J. Chem. Soc. A, 1968, 741;
(b) J. T. Mague and J. P. Mitchener, Inorg. Chem., 1972, 11, 2714.
Coupling to the phosphorus nuclei of the PPh3 ligand as con-
firmed by heteronuclear 1H–31P NMR correlation.
Acknowledgements
4
Typical JPH values for a cis arrangement are in the range 0–4.9
This work was supported by the Ministerio de Ciencia y
´
Tecnologıa (MCyT) of Spain (Projects CAJAL-01-03,
BQU2000-0227 and FEDER 1FD97-0565), the Fundacion
Hz, and in the range 5.8–11.5 Hz for a trans arrangement. See
for example (a) P. Barbaro, C. Bianchini, F. Laschi, S. Midollini,
S. Moneti, G. Scapacci and P. Zanello, Inorg. Chem., 1994, 33,
1622; (b) P. Bhattacharyya, M. L. Loza, J. Parr and A. M. Z.
Slawin, J. Chem. Soc., Dalton Trans., 1999, 2917.
´
´
´
´
para la Investigacion Cientıfica y Tecnica (FICYT) de Asturias
(Project PR-01-GE-4) and the EU (COST programme D12/
0025/99). We thank Dr. E. Lalinde (Universidad de la Rioja)
for Far-IR measurements.
2
cmꢀ1
for
[RuCl2(k -P,N-2-Ph2PC6H4CH
=
10 nRu–Cl ¼ 318
NtBu)(PPh3)]. For NMR data see ref. 5.
11 Complexes 4d,e can also be quantitatively formed starting from
[RuCl2(PPh3)3] and two equivalents of 1d,e. Unfortunately,
attempts to separate 4d,e from free PPh3 failed.
12 D. A. Redfield, L. W. Cary and J. H. Nelson, Inorg. Chem., 1975,
14, 50.
References
1
2
F. Fache, E. Schulz, M. L. Tommasino and M. Lemaire, Chem.
Rev., 2000, 100, 2159 and references therein.
13 W. K. Wong, J.-X. Gao, Z. Y. Zhou and T. C. W. Mak, Polyhe-
dron, 1993, 12, 1415.
14 R. L. Chowdhury and J.-E. Ba¨ckvall, J. Chem. Soc., Chem. Com-
mun., 1991, 1063.
15 D. Maillard, G. Pozzi, S. Quici and D. Sinou, Tetrahedron, 2002,
58, 3971.
16 P. S. Hallman, T. A. Stephenson and G. Wilkinson, Inorg. Synth.,
1970, 12, 237.
17 I. P. Evans, A. Spencer and G. Wilkinson, J. Chem. Soc., Dalton
Trans., 1973, 204.
18 P. Wehman, H. M. A. van Donge, A. Hagos, P. C. J. Kamer and
P. W. N. M. van Leeuwen, J. Organomet. Chem., 1997, 535,
183.
19 B. Crociani, S. Antonaroli, L. Canovese, F. Visentin and P.
Uguagliati, Inorg. Chim. Acta, 2001, 235, 172.
20 C. A. Ghilardi, S. Midollini, S. Moneti, A. Orlandini and
G. Scapacci, J. Chem. Soc., Dalton Trans., 1992, 3371.
21 D. Hedden and D. M. Roundhill, Inorg. Chem., 1985, 24, 4152.
(a) G. Zassinovich, G. Mestroni and S. Gladiani, Chem. Rev.,
1992, 92, 1051; (b) R. Noyori and S. Hashiguchi, Acc. Chem.
Res., 1997, 30, 97; (c) M. J. Palmer and M. Wills, Tetrahedron:
Asymmetry, 1999, 10, 2045; (d ) J.-E. Ba¨ckvall, J. Organomet.
Chem., 2002, 652, 105.
(a) H. Yang, M. Alvarez, N. Lugan and R. Mathieu, J. Chem.
Soc., Chem. Commun., 1995, 1721; (b) Q. Jiang, D. van Plew,
S. Murtuza and X. Zhang, Tetrahedron Lett., 1996, 37, 797; (c)
T. Sammakia and E. L. Stangeland, J. Org. Chem., 1997, 62,
6104; (d ) Y. Arikawa, M. Ueoka, K. Matoba, Y. Nishibayashi,
M. Hidai and S. Uemura, J. Organomet. Chem., 1999, 572, 163;
(e) P. Braunstein, M. D. Fryzuk, F. Naud and S. J. Rettig,
J. Chem. Soc., Dalton Trans., 1999, 589; ( f ) Y. Nishibayashi,
I. Takei, S. Uemura and M. Hidai, Organometallics, 1999, 18,
2291; (g) G. Helmchen and A. Pfaltz, Acc. Chem. Res., 2000,
33, 336; (h) P. Braunstein, C. Graiff, F. Naud, A. Pfaltz and
3
420
New J. Chem., 2003, 27, 414–420