Neutral and cationic (η6-arene)-ruthenium(II) complexes containing the iminophosphorane - Phosphine ligand the arene ring in catalytic transfer hydrogenation of cyclohexanone

Article abstract of DOI:10.1016/S0022-328X(02)01641-8

Ruthenium(II) dimers [{Ru(η⁶-arene)(μ-Cl) Cl}₂] (1a-f) readily react with the iminophosphorane-phosphine ligand Ph₂PCH₂P(=N-p-C₅F₄N) Ph₂ (2), in dichloromethane at room temperatu

Full text of DOI:10.1016/S0022-328X(02)01641-8

Journal of Organometallic Chemistry 663 (2002) 32ꢀ39
/
www.elsevier.com/locate/jorganchem
Neutral and cationic (h6-arene)-ruthenium(II) complexes containing
the iminophosphoraneꢀ N-p-
C5F4N)Ph2: influence of the arene ring in catalytic transfer
/
phosphine ligand Ph2PCH2P(Ä
/
hydrogenation of cyclohexanone
´
Victorio Cadierno, Pascale Crochet, Joaqu´ın Garc´ıa-Alvarez, Sergio E. Garc´ıa-Garrido,
Jose´ Gimeno ꢁ
´ ´ ´ ´ ´ ´
Departamento de Quımica Organica e Inorganica, Facultad de Quımica, Instituto Universitario de Quımica Organometalica ‘Enrique Moles’
(Unidad Asociada al CSIC), Universidad de Oviedo, E-33071 Oviedo, Spain
Received 5 April 2002; accepted 14 June 2002
Dedicated to Professor Pascual Royo in recognition of his pioneering work and leadership in the field of Organometallic Chemistry in Spain
Abstract
Ruthenium(II) dimers [{Ru(h6-arene)(m-Cl)Cl}2] (1aꢀ
N-p-C5F4N)Ph2 (2), in dichloromethane at room temperature, to afford the neutral derivatives [Ru(h6-arene)Cl2{k1-P-
Ph2PCH2P(ÄN-p-C5F4N)Ph2}] (areneꢂ
C6H6 (3a), 1-i Pr-4-C6H4Me (3b), 1,3,5-C6H3Me3 (3c), 1,2,3,4-C6H2Me4 (3d), 1,2,4,5-
C6H2Me4 (3e), C6Me6 (3f)). Treatment of 3aꢀ
f with AgSbF6 in dichloromethane yields the cationic species [Ru(h6-arene)Cl{k2-
P,N-Ph2PCH2P(ÄN-p-C5F4N)Ph2}][SbF6] (4aꢀf). The catalytic activity of complexes 3 and 4 in transfer hydrogenation of
cyclohexanone by propan-2-ol has been studied. Among them, the cationic derivative [Ru(h6-C6Me6)Cl{k2-P,N-Ph2PCH2P(Ä
N-p-
/
f) readily react with the iminophosphoraneꢀ
/
phosphine ligand Ph2PCH2P(Ä
/
/
/
/
/
/
/
C5F4N)Ph2}][SbF6] (4f) shows the highest activity. Electrochemical data for 3 and 4 are also reported.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Hemilabile ligands; (h6-Arene)-ruthenium(II) complexes; Catalytic transfer hydrogenation; Iminophosphoranes
1. Introduction
nophosphoraneꢀ
/
phosphine ligands R2P(CH2)nP(Ä
/
NR)R2, readily accessible via monoimination of dipho-
sphines with azides [3], have shown a great ability for
binding to a wide variety of transition metals [3,4], only
a few complexes have been used as catalysts. To the best
of our knowledge only the catalytic activity of rhodium
(methanol carbonylation and hydrogenation of olefins)
[4e,4h], and nickel and cobalt compounds (methanol
carbonylation) [4e] has been reported to date.
The coordination and organometallic chemistry of
heterodifunctional chelating ligands has been exten-
sively studied. Of special interest are those behaving as
hemilabile ligands, because they can selectively liberate a
coordination site at the metal for substrate binding [1].
The reversible dissociation of one arm of the ligand
provides a highly desirable feature in homogeneous
Recently, we described the preparation of the first
ruthenium(II) complexes containing hemilabile imi-
catalysis. The chemistry of diphosphineꢀ
/
monoxide
ligands R2P(CH2)nP(ÄO)R2 illustrates successful appli-
/
nophosphoraneꢀ
two types of derivatives: (a) neutral k1-P-monodentate
complexes
[Ru(h6-p-cymene)Cl2{k1-P-Ph2PCH2P(Ä
NR)Ph2}] and (b) cationic k2-P,N-bidentate complexes
/phosphine ligands [5]. They belong to
cations in a large number of catalytic transformations
[2]. Although the related heterodifunctional imi-
/
[Ru(h6-p-cymene)Cl{k2-P,N-Ph2PCH2P(Ä
/
NR)Ph2}]ꢃ.
ꢁ Corresponding author. Tel.: ꢃ
446
E-mail address: jgh@sauron.quimica.uniovi.es (J. Gimeno).
/
34-985-103-461; fax: ꢃ34-985-103-
/
The well-known ability of (h6-arene)-ruthenium(II)
species to act as efficient catalysts in hydrogen transfer
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 4 1 - 8

V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ
/39
33
reactions between alcohols and ketones [6] prompted us
to study the catalytic activity of the afore-mentioned
and analogous derivatives. Thus, in this paper we
report: (i) the synthesis and characterization of novel
neutral and cationic ruthenium(II) complexes [Ru(h6-
arene)Cl2(k1-P-PN)] and [Ru(h6-arene)Cl(k2-P,N-
31P{1H}-NMR spectra of all these complexes exhibit the
expected two doublet signals of an AX spin system in
accord with the proposed formulations. Resonance for
the neutral complexes 3aꢀ
8.30ꢀ9.20 (Ph2PÄN) and 22.61ꢀ
37.4ꢀ39.4 Hz) than those of the corresponding cationic
derivatives 4aꢀf (d 52.88ꢀ55.38 (Ph2PÄN) and 45.92ꢀ
17.7 Hz). 19F-NMR spectra
confirm also the mono- or bidentate coordination mode
of the iminophosphoraneꢀphosphine ligand 2. Thus, the
spectra of 3aꢀf display two signals (AA?BB? spin system;
ca. ꢄ157 and ꢄ98 ppm) which appear at similar
chemical shifts to those reported for the free ligand
[4b]. In contrast, the spectra of cationic complexes 4aꢀ
/
f appear at higher fields (d
2
/
/
/
25.40 (Ph2P); JPP
ꢂ
/
/
PN)][SbF6] (PNÄ
/
Ph2PCH2P(Ä
/N-p-C5F4N)Ph2) and (ii)
/
/
/
/
2
the catalytic activity of iminophosphoraneꢀ
/
phosphine
47.90 (Ph2P); JPP
ꢂ
/
14.0ꢀ
/
ruthenium(II) complexes in the transfer hydrogenation
of cyclohexanone by propan-2-ol.
/
/
/
/
2. Results
/f
show four sets of multiplets indicating the inequivalence
of the fluorine nuclei which arises probably from the
presence of stereogenic ruthenium atoms. 1H- and
13C{1H}-NMR spectra exhibit signals in accordance
with the proposed structures (see Section 4), being the
most significant features those concerning the methyle-
2.1. Synthesis and characterization of complexes
[Ru(h6-arene)Cl2{k1-P-Ph2PCH2P(Ä
/
N-p-
C5F4N)Ph2}] and [Ru(h6-arene)Cl{k2-P,N-
Ph2PCH2P(ÄN-p-C5F4N)Ph2}][SbF6]
/
The reaction of the dimers [{Ru(h6-arene)(m-Cl)Cl}2]
(1aꢀf) [7] with two equivalents of the imi-
nophosphoraneꢀphosphine ligand Ph2PCH2P(ÄN-p-
nic group of the iminophosphoraneꢀ
/
phosphine ligand 2:
(i) (1H-NMR), a doublet of doublets signal for 3aꢀ
/
/
f (d
10.8 Hz) and one or two
2
4.42; JHPꢂ2
/
J
HP?ꢂ
/
9.9ꢀ
/
/
/
4.25ꢀ
/
C5F4N)Ph2 (2) [4b], in dichloromethane at room tem-
perature, leads to complexes [Ru(h6-arene)Cl2{k1-P-
unresolved multiplets for 4aꢀ
(13C{1H}-NMR), a characteristic doublet of doublets
resonance in the ranges 22.16ꢀ25.82 (3aꢀf; JCP 50.7ꢀ
57.1 and 16.9ꢀ19.2 Hz) and 30.10ꢀ33.44 (4aꢀf; JCP
77.4ꢀ79.8 and 19.2ꢀ20.6 Hz) ppm.
/
f (d 3.46ꢀ4.18). (ii)
/
Ph2PCH2P(Ä
/
N-p-C5F4N)Ph2}] (areneꢂC6H6 (3a),
/
/
/
ꢂ
/
/
1-iPr-4-C6H4Me (3b) [5], 1,3,5-C6H3Me3 (3c), 1,2,3,4-
C6H2Me4 (3d), 1,2,4,5-C6H2Me4 (3e), C6Me6 (3f)) in
/
/
/
ꢂ
/
/
/
81ꢀ
slight excess of AgSbF6 gives the cationic deriva-
tives N-p-
[Ru(h6-arene)Cl{k2-P,N-Ph2PCH2P(Ä
C5F4N)Ph2}][SbF6] (4aꢀf) (77ꢀ86%, Scheme 1), which
/
91% yield (see Scheme 1). Treatment of 3aꢀf with a
/
2.2. Electrochemical studies of complexes [Ru(h6-
arene)Cl2{k1-P-Ph2PCH2P(Ä
N-p-C5F4N)Ph2}] and
[Ru(h6-arene)Cl{k2-P,N-Ph2PCH2P(Ä
N-p-
C5F4N)Ph2}][SbF6]
/
/
/
/
/
are readily formed via N-coordination of the free
iminophosphorane group.
Compounds 3aꢀ
/
f, 4aꢀf have been isolated as air-
/
The redox behavior of complexes 3aꢀ
/
f, 4aꢀ
/
f has been
investigated using CV. The CV of all the complexes
stable orange solids. They have been characterized by
elemental analyses, conductance measurements and
NMR (1H-, 31P{1H}-, 19F-, 13C{1H}-) spectroscopy
(details are given in Section 4). The room-temperature
showed a quasi-reversible oxidation wave corresponding
to the Ru2ꢃ ꢀRu3ꢃ redox system. Formal potentials
/
(E8?) values (see Table 1) are given versus the [Cp2Fe]ꢀ
/
Table 1
Electrochemical data for complexes 3aꢀ
a
/
f and 4aꢀf
/
Neutral complexes 3aꢀ
/f
Cationic complexes 4aꢀf
/
b
b
Complex
E8? (V)
Complex
E8? (V)
3a
3b
3c
3d
3e
3f
1.09
0.79
0.76
0.65
0.74
0.66
4a
4b
4c
4d
4e
4f
1.06
0.98
0.92
0.56
0.78
0.61
a
Measured at 0.1 V sꢄ1 in dichloromethane with a 0.03 M solution
of [n Bu4N][PF6] as the supporting electrolyte.
b
Scheme 1. Synthesis of (h6-arene)-ruthenium(II) complexes contain-
Formal potentials (E8?) are referenced relative to potential of the
ing the iminophosphorane-phosphine ligand Ph2PCH2P(ꢂ
/N-p-
[Cp2Fe]ꢀ
/
[Cp2Fe]ꢃ couple (E8ꢂ0.26 V). E8?ꢂE8(Complexꢃ/Com-
C5F4N)Ph2.
plex)ꢄE8([Cp2Fe]ꢃ/[Cp2Fe]).

34
V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ39
/
[Cp2Fe]ꢃ redox couple [8]. For both neutral and
Table 2
Transfer hydrogenation of cyclohexanone
a
cationic complexes, E8? decreases in the sequence
C6H6 (a)ꢀ
/
1-iPr-4-C6H4Me (b)ꢀ
/
1,3,5-C6H3Me3 (c)ꢀ
/
b
c
Entry
Catalyst
Yield (%)
TOF50 (hꢄ1
)
1,2,4,5-C6H2Me4 (e)ꢀ
/
C6Me6 (f). Similar trends have
[Ru(h6 -arene)Cl2 {k1 -P-Ph2 PCH2 P(ÄN-p-C5 F4 N)Ph2 }]
been reported for analogous (h6-arene)-ruthenium(II)
complexes [9] in accord with the increasing electron-
releasing properties of the arene ring. These observa-
tions are also consistent with theoretical studies which
indicate that the HOMO energy level decreases when
substituting Me by H in an arene-complex [10]. How-
ever, E8? values found for compounds 3d and 4d,
containing the 1,2,3,4-C6H2Me4 ligand, are unexpect-
edly lower than those of their hexamethylbenzene
counterparts 3f and 4f, i.e. 0.65 versus 0.66 V and 0.56
versus 0.61 V, respectively. Although we have no
explanation for this feature, it is apparent that the
hexamethylbenzene derivatives are prone to reduce the
electron density of the ruthenium atom in a greater
extent than their 1,2,3,4-C6H2Me4 counterparts [11].
1
2
3
4
5
6
3a
3b
3c
3d
3e
3f
68 (ꢀ99)
29 (88)
38 (95)
77
23
29
59
37
153
55 (ꢀ99)
43 (98)
73 (ꢀ99)
[Ru(h6 -arene)Cl{k2 -P,N-Ph2 PCH2 P(ꢂN-p-C5 F4 N)Ph2 }][SbF6 ]
7
4a
4b
4c
4d
4e
4f
71 (ꢀ99)
22 (ꢀ99)
33 (ꢀ99)
53 (ꢀ99)
38 (95)
82
20
28
53
26
249
8
9
10
11
12
d
ꢀ99
a
Conditions: reactions were carried out at 82 8C using 5 mmol of
i
cyclohexanone (0.2 M in PrOH). Ketone/catalyst/NaOH ratio: 250/1/
24.
b
Yield of cyclohexanol after 2.5 h (yield after 24 h in parentheses).
GC determined.
c
2.3. Catalytic transfer hydrogenation of cyclohexanone
Turnover frequencies ((mol product/mol catalyst)/time) were
calculated at 50% conversion.
d
The catalytic activity of complexes 3aꢀ
/
f and 4aꢀf in
/
Yield after 1 h.
the transfer hydrogenation of cyclohexanone by propan-
2-ol has been investigated (Scheme 2). In a typical
experiment, the ruthenium(II) catalyst precursor (0.4
mol%) and NaOH (9.6 mol%) were added to a 0.2 M
solution of cyclohexanone in iPrOH at 82 8C, the
reaction being monitored by gas chromatography.
Selected results are shown in Table 2.
ing h6-methyl-substituted arene rings, i.e. [Ru(h6-are-
ne)Cl2{k1-P-Ph2PCH2P(Ä
/
N-p-C5F4N)Ph2}] (3a, cꢀ
and [Ru(h6-arene)Cl{k2-P,N-Ph2PCH2P(Ä
N-p-C5F4-
N)Ph2}][SbF6] (4a, cꢀf) (areneꢂC6HnMe6ꢄn; nꢂ0, 2,
/f)
/
/
/
/
3, 6), have been prepared in good yields [12]. As
expected, in accord with the catalytic activity shown
by ruthenium(II) complexes bearing heterodifunctional
Both neutral 3aꢀ
/
e and cationic 4aꢀe complexes have
/
proven to be active and efficient catalysts leading to
nearly quantitative conversions after 24 h, with no
significant difference between the catalytic activity of
neutral and the corresponding cationic complex (see
P,N-ligands [13,14], compounds 3aꢀ
/
f and 4aꢀf are
/
active in the catalytic transfer hydrogenation of cyclo-
hexanone leading to nearly quantitative formation of
cyclohexanol after 24 h. With regard to comparative
catalytic performance with respect to analogous com-
plexes, the following features are worth to be noted: (a)
in general, the efficiencies are lower than those of
neutral octahedral ruthenium(II) complexes bearing bi-
or tridentate phosphino-oxazolines, pyridyl-phosphines
and imino-phosphines [13]. (b) The catalytic perfor-
mance shown by the cationic complex 4f is higher to that
recently reported for the related half-sandwich cationic
entries 1ꢀ
/
5 vs. 7ꢀ11). However, this does not hold for
/
the complex 3f with respect to the cationic analogue 4f
(TOF50 of 153 vs. 249 hꢄ1; entries 6 and 12) since for the
latter a complete conversion of cyclohexanone into
cyclohexanol is accomplished after 1 h (entry 12).
3. Discussion
species
[Ru(h6-1-iPr-4-C6H4Me)Cl{k2-P,N-(N,N-di-
Following the synthetic procedure described for the
phosphine complexes [Ru(h6-1-iPr-
/
methyl-2-diphenylphosphinoethyl)amine}][CF3SO3]
[14a] and [Ru(h6-1-i Pr-4-C6H4Me)Cl{k2-P,N-2-(1-
N,N-dimethylaminoethyl)-1-diphenylphosphinoferroce-
ne}][CF3SO3] [14a], and comparable to that of cationic
iminophosphoraneꢀ
/
4-C6H4Me)Cl2{k1-P-Ph2PCH2P(Ä
NR)Ph2}]
and
NR)-
Ph2}][PF6] [5], a series of analogous derivatives contain-
[Ru(h6-1-iPr-4-C6H4Me)Cl{k2-P,N-Ph2PCH2P(Ä
/
phosphinoꢀ
oxazoline complexes [Ru(h6-C6H6)Cl{k2-
/
P,N-bis(2-oxazolin-2-ylmethyl)phenylphosphine}][CF3-
SO3] [14b] and [Ru(h6-1-iPr-4-C6H4Me)Cl{k2-P,N-(2-
oxazolin-2-ylmethyl)diphenylphosphine}][CF3SO3]
[14c]. In general, the catalytic efficiency seems to be
strongly dependent on the arene ligand, the rate order
Scheme 2. Catalytic transfer hydrogenation of cyclohexanone by
propan-2-ol.
observed being: C6Me6 (f)
ꢀ/C6H6 (a)
ꢀ1,2,3,4-
/

V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ
/39
35
C6H2Me4 (d) ꢀ
/
1,2,4,5-C6H2Me4 (e) :
/
1,3,5-C6H3Me3
4. Experimental
(c) ꢀ
/
1-iPr-4-C6H4Me (b).
The manipulations were performed under an atmo-
sphere of dry nitrogen using vacuum-line and standard
Schlenk techniques. Solvents were dried by standard
methods and distilled under nitrogen before use. Com-
Although no mechanistic studies have been per-
formed, the catalytic transformation most probably
follows the classical pathway as is summarized in
Scheme 3 [14a]. The active species consists of an iso-
propoxide complex A which, is readily formed from 4 in
the presence of a base. Complexes 3 are also suitable
precatalysts through an initial chloride dissociation,
favored by the polar solvent, which readily leads to
complexes 4. b-elimination from A generates the hydride
complex B [15] to which cyclohexanone coordinates via
pounds [{Ru(h6-arene)(m-Cl)Cl}2] (1) [17], Ph2PCH2P(Ä
N-p-C5F4N)Ph2 (2) [4b] and [Ru(h6-p-cymene)Cl2{k1-
P-Ph2PCH2P(ÄN-p-C5F4N)Ph2}] (3b) [5] were prepared
by following the methods reported in the literature. Gas
chromatographic measurements were made on
HewlettꢀPackard HP6890 equipment. A HP-INNO-
/
/
a
/
WAX cross-linked poly(ethylene glycol) column (30 m,
250 mm) was used. The C, H and N analyses were carried
RuÃ/N cleavage leading to intermediate C [16]. Finally,
hydride transfer from ruthenium to the carbonyl group
occurs to yield E which regenerates A by alkoxide
exchange.
An experimental support of this mechanism relies in
the fact that the catalytic activity remains unaffected in
out with a PerkinꢀElmer 2400 microanalyzer. Conduc-
/
tivity was measured at room temperature (r.t.), in ca.
10ꢄ3 mol dmꢄ3 acetone solutions, with a Jenway PCM3
conductometer. NMR spectra were recorded on a
Bruker DPX-300 instrument at 300 MHz (1H), 121.5
MHz (31P), 282.4 MHz (19F) or 75.4 MHz (13C) using
SiMe4, C6F6 or 85% H3PO4 as standards. DEPT
experiments have been carried out for all the compounds
reported. Abbreviations used: s, singlet; d, doublet; dd,
doublet of doublets; m, multiplet.
the presence of free arene ([arene]/[Ru]ꢂ/250/1) or free
iminophosphoraneꢀphosphine ligand ([2]/[Ru]ꢂ
/
/3/1).
This clearly indicates that the active species does not
result from the dissociation of these ligands in the
catalyst precursors 3aꢀ
/
f, 4aꢀf. Apparently, the catalytic
/
activity of these species does not depend exclusively on
the steric or electronic properties of the metal fragment
since: (i) the best results have been obtained when
benzene and hexamethylbenzene are used (see entries
1, 6, 7 and 12 in Table 2), and (ii) the catalytic rate (see
above) does not follow the same trend observed for the
4.1. Synthesis of [Ru(h6-arene)Cl2{k1-P-Ph2PCH2P(Ä
N-p-C5F4N)Ph2}] (areneꢂC6H6 (3a), 1,3,5-C6H3Me3
(3c), 1,2,3,4-C6H2Me4 (3d), 1,2,4,5-C6H2Me4 (3e),
/
/
C6Me6 (3f))
oxidation potentials (1,2,3,4-C6H2Me4 (d) ꢀ
1,2,4,5-C6H2Me4 (e) ꢀ1,3,5-C6H3Me3 (c) ꢀ
C6H4Me (b) ꢀC6H6 (a)).
/
C6Me6 (f)
A solution of the iminophosphorane-phosphine li-
gand Ph2PCH2P(ÄN-p-C5F4N)Ph2 (2) (1.1 g, 2 mmol)
and the corresponding dimer [{Ru(h6-arene)(m-Cl)Cl}2]
ꢀ
/
/
/
1-iPr-4-
/
/
Scheme 3. Proposed catalytic cycle for the transfer hydrogenation of cyclohexanone by propan-2-ol.

36
V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ39
/
(1) (1 mmol) in 50 ml of dichloromethane was stirred at
r.t. for 4 h and then evaporated to dryness. The orange
Compound 3f: yield, 1.430 g (81%). Anal. Calc. for
RuC42H40F4Cl2N2P2 (882.72 g molꢄ1): C, 57.15; H,
4.57; N, 3.17. Found: C, 57.11; H, 4.48; N, 3.22%;
solid residue was washed with pentane (3ꢅ/10 ml) and
2
dried in vacuo. Compound 3a: yield, 1.389 g (87%).
Anal. Calc. for RuC36H28F4Cl2N2P2 (798.55 g molꢄ1):
C, 54.15; H, 3.53; N, 3.51. Found: C, 54.01; H, 3.45; N,
31P{1H}-NMR (CDCl3) dꢂ
/
9.02 (d, JPP
ꢂ38.1 Hz,
/
2
Ph2PÄ
NMR (CDCl3) dꢂ
C5F4N) ppm; 1H-NMR (CDCl3) dꢂ
/
N), 24.70 (d, JPP
ꢂ
/
38.1 Hz, Ph2P) ppm; 19F-
98.85 (m, 2F each,
1.60 (s, 18H, CH3),
10.2 Hz, PCH2P),
8.02 (m, 4H, Ph) ppm;
15.34 (s, CH3), 25.82 (dd,
17.5 Hz, PCH2P), 96.74 (d, 2JCP
2.9 Hz, C6Me6), 126.93ꢀ149.37 (m, Ph and C5F4N)
ppm.
/
ꢄ
/
157.33 and ꢄ
/
2
9.20 (d, JPP
3.47%; 31P{1H}-NMR (CDCl3) dꢂ
/
ꢂ
/
37.4
/
2
2
Hz, Ph2PÄ
NMR (CDCl3) dꢂ
C5F4N) ppm; 1H-NMR (CDCl3) dꢂ
/
N), 22.61 (d, 2JPP
ꢂ
/
37.4 Hz, Ph2P) ppm; 19F-
98.43 (m, 2F each,
4.42 (dd, 2H, JHP
7.13ꢀ7.49 (m, 16H, Ph), 7.97ꢀ
13C{1H}-NMR (CDCl3) dꢂ
JCP 50.7 Hz, JCP
ꢂ
/
10.2 Hz, JHP
ꢂ
/
/
ꢄ
/
157.13 and ꢄ
/
/
/
/4.25 (dd, 2H,
/
2JHP
C6H6), 7.19ꢀ
ppm; 13C{1H}-NMR (CDCl3) dꢂ
Hz, JCP 19.2 Hz, PCH2P), 88.92 (d, JCP
C6H6), 128.20ꢀ150.01 (m, Ph and C5F4N) ppm. Com-
ꢂ
/
10.8 Hz, JHP
ꢂ
/
10.8 Hz, PCH2P), 5.24 (s, 6H,
ꢂ
/
ꢂ
/
ꢂ
/
2
/
7.47 (m, 16H, Ph), 7.89ꢀ
/
7.95 (m, 4H, Ph)
57.1
3.5 Hz,
/
/
22.16 (dd, JCP
ꢂ
/
2
ꢂ
/
ꢂ
/
/
4.2. Synthesis of [Ru(h6-arene)Cl{k2-P,N-
Ph2PCH2P(ÄN-p-C5F4N)Ph2}][SbF6] (areneꢂ
(4a), 1-iPr-4-C6H4Me (4b), 1,3,5-C6H3Me3 (4c),
pound 3c: yield, 1.530 g (91%). Anal. Calc. for
RuC39H34F4Cl2N2P2 (840.63 g molꢄ1): C, 55.72; H,
4.08; N, 3.33. Found: C, 55.64; H, 4.12; N, 3.19%;
/
/C6H6
1,2,3,4-C6H2Me4 (4d), 1,2,4,5-C6H2Me4 (4e), C6Me6
(4f))
2
31P{1H}-NMR (CDCl3) dꢂ
/
9.12 (d, JPP
ꢂ37.4 Hz,
/
2
Ph2PÄ
/
N), 24.02 (d, JPP
157.18 and ꢄ
C5F4N) ppm; H-NMR (CDCl3) dꢂ
ꢂ
/
37.4 Hz, Ph2P) ppm; 19F-
98.60 (m, 2F each,
1.75 (s, 9H, CH3),
10.5 Hz, PCH2P),
7.50 (m, 16H, Ph), 7.99ꢀ
8.06 (m, 4H, Ph) ppm; 13C{1H}-NMR (CDCl3) dꢂ
18.61 (s, CH3), 24.05 (dd, JCP 52.4 Hz, JCP 18.6
Hz, PCH2P), 86.26 (d, 2JCP
4.1 Hz, CH of C6H3Me3),
103.25 (d, 2JCP
2.3 Hz, C of C6H3Me3), 127.98ꢀ146.09
NMR (CDCl3) dꢂ
/
ꢄ
/
/
A suspension of complexes 3aꢀf (1 mmol) and
/
1
/
AgSbF6 (0.378 g, 1.1 mmol) in 40 ml of dichloro-
methane was stirred in the dark, at r.t., for 4 h. The
reaction mixture was then filtered through Kieselguhr
and the filtrate concentrated to dryness. The resulting
2
2
4.38 (dd, 2H, JHP
ꢂ
/
10.5 Hz, JHP
ꢂ
/
4.57 (s, 3H, C6H3Me3), 7.13ꢀ
/
/
/
ꢂ
/
ꢂ
/
orange solid residue was washed with diethyl ether (3ꢅ
/
ꢂ
/
20 ml) and dried in vacuo. Compound 4a: yield, 0.799 g
(80%). Anal. Calc. for RuC36H28F10N2P2ClSb (998.84 g
molꢄ1): C, 43.29; H, 2.82; N, 2.80. Found: C, 43.45; H,
ꢂ
/
/
(m, Ph and C5F4N) ppm. Compound 3d: yield, 1.453 g
(85%). Anal. Calc. for RuC40H36F4Cl2N2P2 (854.66 g
molꢄ1): C, 56.21; H, 4.24; N, 3.28. Found: C, 56.02; H,
2.73; N, 2.78%; conductivity: 110 Vꢄ1 cm2 molꢄ1
;
2
31P{1H}-NMR (CD2Cl2) dꢂ
/
45.92 (d, JPP
ꢂ
/
17.7 Hz,
N) ppm; 19F-
138.13, ꢄ89.42 and
89.12 (m, 1F each, C5F4N) ppm; H-NMR (CD2Cl2)
dꢂ3.65 and 4.13 (m, 1H each, PCH2P), 5.51 (s, 6H,
C6H6), 6.74 (m, 2H, Ph), 7.26ꢀ7.77 (m, 18H, Ph) ppm;
13C{1H}-NMR (CD2Cl2) dꢂ
30.10 (dd, JCP 78.6 Hz,
JCP 19.8 Hz, PCH2P), 89.45 (d, JCP 1.7 Hz, C6H6),
124.01ꢀ147.04 (m, Ph and C5F4N) ppm. Compound 4b:
4.15; N, 3.40%; 31P{1H}-NMR (CDCl3) dꢂ
/
8.30 (d,
Ph2P), 55.38 (d, JPP
ꢂ
/
17.7 Hz, Ph2Pꢂ
/
2
2
N), 25.40 (d, JPP
2JPP
Ph2P) ppm; 19F-NMR (CDCl3) dꢂ
ꢂ
/
39.4 Hz, Ph2PÄ
/
ꢂ
/
39.4 Hz,
NMR (CD2Cl2) dꢂ
/
ꢄ
/
143.30, ꢄ
/
/
1
/
ꢄ
/
157.15 and ꢄ
98.50 (m, 2F each, C5F4N) ppm; 1H-NMR (CDCl3)
dꢂ1.54 (s, 6H, CH3), 2.05 (d, 6H, JHH 1.9 Hz, CH3),
4.13 (d, 2H, JHH 1.9 Hz, C6H2Me4), 4.40 (dd, 2H,
10.2 Hz, JHP 10.2 Hz, PCH2P), 7.17ꢀ7.54 (m,
16H, Ph), 7.85ꢀ
7.93 (m, 4H, Ph) ppm; 13C{1H}-NMR
(CDCl3) dꢂ14.04 and 17.49 (s, CH3), 23.22 (dd, JCP
53.1 Hz, JCP 16.9 Hz, PCH2P), 84.12 (s, CH of
C6H2Me4), 94.92 (s, C of C6H2Me4), 105.05 (d, JCP
11.3 Hz, C of C6H2Me4), 127.86ꢀ146.13 (m, Ph and
/
ꢄ
/
/
/
ꢂ
/
/
ꢂ
/
/
ꢂ
/
2
2
2JHP
ꢂ
/
ꢂ
/
/
ꢂ
/
ꢂ
/
/
/
/
ꢂ
/
yield, 0.886 g (84%). Anal. Calc. for RuC40H36-
F10N2P2ClSb (1054.95 g molꢄ1): C, 45.54; H, 3.44; N,
2.65. Found: C, 45.37; H, 3.39; N, 2.50%; conductivity:
107 Vꢄ1 cm2 molꢄ1; NMR data in accord with those
/
ꢂ
/
2
ꢂ
/
/
C5F4N) ppm. Compound 3e: yield, 1.504 g (88%). Anal.
Calc. for RuC40H36F4Cl2N2P2 (854.66 g molꢄ1): C,
56.21; H, 4.24; N, 3.28. Found: C, 56.30; H, 4.11; N,
reported for [Ru(h6-p-cymene)Cl{k2-P,N-Ph2PCH2P(Ä
N-p-C5F4N)Ph2}][PF6] [5]. Compound 4c: yield, 0.822 g
(79%). Anal. Calc. for RuC39H34F10N2P2ClSb (1040.92
g molꢄ1): C, 45.00; H, 3.29; N, 2.69. Found: C, 44.82;
2
3.20%; 31P{1H}-NMR (CDCl3) dꢂ
/
8.98 (d, JPP
ꢂ37.4
/
Hz, Ph2PÄ
NMR (CDCl3) dꢂ
C5F4N) ppm; 1H-NMR (CDCl3) dꢂ
/
N), 23.02 (d, 2JPP
ꢂ
/
37.4 Hz, Ph2P) ppm; 19F-
98.71 (m, 2F each,
1.54 (s, 12H, CH3),
9.9 Hz, PCH2P),
7.45 (m, 16H, Ph), 7.92 (m,
4H, Ph) ppm; 13C{1H}-NMR (CDCl3) dꢂ
16.22 (s,
CH3), 23.68 (dd, JCP 54.2 Hz, JCP 18.0 Hz, PCH2P),
92.18 (d, 2JCP
5.8 Hz, CH of C6H2Me4), 97.50 (s, C of
C6H2Me4), 127.94ꢀ146.10 (m, Ph and C5F4N) ppm.
H, 3.17; N, 2.77%; conductivity: 114 Vꢄ1 cm2 molꢄ1
;
2
/
ꢄ
/
157.21 and ꢄ
/
31P{1H}-NMR (CD2Cl2) dꢂ
/
47.10 (d, JPP
ꢂ
/
14.0 Hz,
N) ppm; 19F-
135.97, ꢄ90.46 and
89.42 (m, 1F each, C5F4N) ppm; H-NMR (CD2Cl2)
dꢂ1.85 (s, 9H, CH3), 3.86 (m, 2H, PCH2P), 4.84 (s, 3H,
C6H3Me3), 6.68 (m, 2H, Ph), 7.21ꢀ7.96 (m, 18H, Ph)
ppm; 13C{1H}-NMR (CD2Cl2) dꢂ
18.35 (s, CH3), 33.15
(dd, JCP 79.8 Hz, JCP 19.2 Hz, PCH2P), 87.86 (s,
2
/
Ph2P), 53.58 (d, JPP
ꢂ
/
14.0 Hz, Ph2Pꢂ
/
2
2
4.35 (dd, 2H, JHP
ꢂ
/
9.9 Hz, JHP
ꢂ
/
NMR (CD2Cl2) dꢂ
/
ꢄ
/
141.43, ꢄ
/
/
1
4.73 (s, 2H, C6H2Me4), 7.18ꢀ
/
ꢄ
/
/
/
ꢂ
/
ꢂ
/
/
ꢂ
/
/
/
ꢂ
/
ꢂ
/

V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ
/39
37
CH of C6H3Me3), 103.98 (s, C of C6H3Me3), 128.67ꢀ
/
10 ml) and dried in vacuo. Compound 5: yield, 1.023 g
(90%). Anal. Calc. for RuC28H29Cl2P (568.49 g molꢄ1):
150.55 (m, Ph and C5F4N) ppm. Compound 4d: yield,
0.907 g (86%). Anal. Calc. for RuC40H36F10N2P2ClSb
(1054.95 g molꢄ1): C, 45.54; H, 3.44; N, 2.65. Found: C,
45.42; H, 3.47; N, 2.56%; conductivity: 111 Vꢄ1 cm2
C, 59.16; H, 5.14. Found: C, 58.91; H, 5.20%; 31P{1H}-
1
NMR (CDCl3) dꢂ
dꢂ
C6H2Me4), 7.35 (m, 9H, Ph), 7.77 (m, 6H, Ph) ppm;
13C{1H}-NMR (CDCl3) dꢂ
13.61 and 17.36 (s, CH3),
83.72 (s, CH of C6H2Me4), 95.21 (s, C of C6H2Me4),
/29.30 (s) ppm; H-NMR (CDCl3)
/
1.84 and 2.08 (s, 6H each, CH3), 4.04 (s, 2H,
2
46.55 (d, JPP
molꢄ1
;
31P{1H}-NMR (CD2Cl2) dꢂ
/
ꢂ
N)
/
2
15.7 Hz, Ph2P), 52.99 (d, JPP
ppm; 19F-NMR (CD2Cl2) dꢂ
90.11 and ꢄ
89.80 (m, 1F each, C5F4N) ppm; 1H-
NMR (CD2Cl2) dꢂ1.47, 1.54, 1.84 and 1.88 (s, 3H
each, CH3), 3.60 and 4.18 (m, 1H each, PCH2P), 4.92
and 5.18 (d, 1H each, JHH 5.6 Hz, C6H2Me4), 6.54 (m,
2H, Ph), 7.11ꢀ
7.95 (m, 18H, Ph) ppm; 13C{1H}-NMR
(CD2Cl2) dꢂ14.39, 14.50, 17.14 and 18.52 (s, CH3),
32.67 (dd, JCP 78.1 Hz, JCP 19.9 Hz, PCH2P), 82.17
(s, CH of C6H2Me4), 91.90 (d, JCP
C6H2Me4), 95.78 and 96.26 (s, C of C6H2Me4), 104.83
ꢂ
/
15.7 Hz, Ph2Pꢂ
/
/
/
ꢄ
/
142.20, ꢄ138.71, ꢄ
/
/
2
/
104.71 (d, JCP
JCP 9.9 Hz, CH of Ph), 129.94 (s, CH of Ph), 134.08
(d, JCP 9.3 Hz, CH of Ph), 134.79 (d, JCP 45.4 Hz, C
ꢂ
/
10.5 Hz, C of C6H2Me4), 127.78 (d,
/
ꢂ
/
ꢂ
/
ꢂ
/
ꢂ
/
of Ph) ppm. Compound 6: yield, 0.711 g (93%). Anal.
Calc. for RuC13H23Cl2P (382.28 g molꢄ1): C, 40.85; H,
6.06. Found: C, 40.71; H, 5.99%; 31P{1H}-NMR
/
/
1
ꢂ
/
ꢂ
/
(CDCl3) dꢂ
/
6.55 (s) ppm; H-NMR (CDCl3) dꢂ
/1.57
2
2
ꢂ2.8 Hz, CH of
/
(d, 9H, JHP
(d, 6H, JHH
C6H2Me4) ppm; 13C{1H}-NMR (CDCl3) dꢂ
18.08 (s, CH3), 16.96 (d, JCP 32.6 Hz, PCH3), 79.16 (s,
CH of C6H2Me4), 93.68 (s, C of C6H2Me4), 105.76 (d,
2JCP
10.3 Hz, C of C6H2Me4) ppm.
ꢂ
ꢂ
/
10.2 Hz, PCH3), 1.90 (s, 6H, CH3), 2.10
2.8 Hz, CH3), 4.79 (d, 2H, JHH 2.8 Hz,
13.75 and
/
ꢂ
/
2
2
(d, JCP
ꢂ
/
5.0 Hz, C of C6H2Me4), 106.38 (d, JCP
ꢂ7.8
/
/
Hz, C of C6H2Me4), 124.31ꢀ/147.78 (m, Ph and C5F4N)
ꢂ
/
ppm. Compound 4e: yield, 0.897 g (85%). Anal. Calc.
for RuC40H36F10N2P2ClSb (1054.95 g molꢄ1): C, 45.54;
H, 3.44; N, 2.65. Found: C, 45.39; H, 3.40; N, 2.71%;
ꢂ
/
conductivity: 105 Vꢄ1 cm2 molꢄ1
;
31P{1H}-NMR
2
(CD2Cl2) dꢂ
2JPP
dꢂ
each, C5F4N) ppm; 1H-NMR (CD2Cl2) dꢂ
1.86 (s, 6H each, CH3), 3.96 (m, 2H, PCH2P), 4.86 (s,
2H, C6H2Me4), 6.59 (m, 2H, Ph), 7.21ꢀ7.77 (m, 18H,
Ph) ppm; 13C{1H}-NMR (CD2Cl2) dꢂ
15.71 and 16.65
(s, CH3), 30.33 (dd, JCP 78.1 Hz, JCP 20.6 Hz,
3.5 Hz, CH of C6H2Me4),
/
47.90 (d, JPP
ꢂ
/
14.6 Hz, Ph2P), 53.67 (d,
N) ppm; 19F-NMR (CD2Cl2)
136.71, ꢄ90.21 and ꢄ89.42 (m, 1F
1.46 and
4.4. Electrochemistry
ꢂ
/
14.6 Hz, Ph2Pꢂ
/
/
ꢄ142.83, ꢄ
/
/
/
/
CV measurements (25 8C) were carried out with a
three-electrode system. The working electrode was a
platinum disk electrode, the counter electrode was a
platinum spiral, and the reference electrode was an
aqueous saturated calomel electrode (SCE) separated
from the solution by a porous septum. Current and
voltage parameters were controlled using a PAR system
M273. In a typical experiment, 0.15 mmol of the
complex was dissolved under a nitrogen atmosphere in
10 ml of freshly distilled and deoxygenated dichloro-
methane containing 1.15 g of pure [nBu4N][PF6] (0.3
mmol) as electrolyte. Formal CV potentials (E8?) are
/
/
/
ꢂ
/
ꢂ
/
2
PCH2P), 91.08 (d, JCP
94.65 (s, C of C6H2Me4), 104.01 (d, JCP
C6H2Me4), 124.83ꢀ147.05 (m, Ph and C5F4N) ppm.
ꢂ
/
2
ꢂ5.7 Hz, C of
/
/
Compound 4f: yield, 0.834 g (77%). Anal. Calc. for
RuC42H40F10N2P2ClSb (1083.00 g molꢄ1): C, 46.58; H,
3.72; N, 2.59. Found: C, 46.31; H, 3.66; N, 2.70%;
conductivity: 108 Vꢄ1 cm2 molꢄ1
;
31P{1H}-NMR
2
referenced relative to potential of the [Cp2Fe]ꢀ
couple (E8ꢂ0.26 V) run under identical condi-
tions (E8?ꢂ
E8(Complexꢃ/Complex)ꢄE8([Cp2Fe]ꢃ/
[Cp2Fe])) [8].
/
[Cp2Fe]ꢃ
(CD2Cl2) dꢂ
2JPP
dꢂ
each, C5F4N) ppm; 1H-NMR (CD2Cl2) dꢂ
CH3), 3.46 and 4.06 (m, 1H each, PCH2P), 6.22 (m, 2H,
Ph), 7.04ꢀ
7.99 (m, 18H, Ph) ppm; 13C{1H}-NMR
(CD2Cl2) dꢂ15.80 (s, CH3), 33.44 (dd, JCP 77.4 Hz,
JCP 19.7 Hz, PCH2P), 98.61 (d, JCP 2.6 Hz,
C6Me6), 126.95ꢀ148.50 (m, Ph and C5F4N) ppm.
/
47.67 (d, JPP
ꢂ
/
14.6 Hz, Ph2P), 52.82 (d,
N) ppm; 19F-NMR (CD2Cl2)
136.80, ꢄ90.12 and ꢄ89.31 (m, 1F
1.66 (s, 18H,
ꢂ
/
14.6 Hz, Ph2Pꢂ
/
/
/
ꢄ142.77, ꢄ
/
/
/
/
/
/
/
/
/
ꢂ
/
2
4.5. General procedure for catalytic transfer
hydrogenation of cyclohexanone
ꢂ
/
ꢂ
/
/
4.3. Synthesis of [Ru(h6-1,2,3,4-C6H2Me4)Cl2(PR3)]
(PR3ꢂPPh3 (5), PMe3 (6))
Under inert atmosphere cyclohexanone (0.49 g, 5
mmol), the ruthenium catalyst precursor (0.02 mmol, 0.4
mol%), and 20 ml of propan-2-ol are introduced in a
Schlenk tube fitted with a condenser and heated at
82 8C for 15 min. Then NaOH is added (5 ml of a 0.096
M solution in propan-2-ol, 9.6 mol%) and the reaction is
monitored by gas chomatography. Cyclohexanol and
acetone are the only products detected in all cases.
/
A solution of the corresponding phosphine (2 mmol)
and the dimer [{Ru(h6-1,2,3,4-C6H2Me4)(m-Cl)Cl}2]
(1d) (0.612 g, 1 mmol) in 50 ml of dichloromethane
was stirred at r.t. for 3 h and then evaporated to dryness.
The orange solid residue was washed with pentane (3ꢅ
/

38
V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ39
/
(c) T. Naota, H. Takaya, S.-I. Murahashi, Chem. Rev. 98 (1998)
2599;
Acknowledgements
(d) M.J. Palmer, M. Wills, Tetrahedron Asymm. 10 (1999) 2045;
(e) F. Fache, E. Schulz, M.L. Tommasino, M. Lemaire, Chem.
Rev. 100 (2000) 2159;
This work was supported by the Ministerio de Ciencia
y Tecnolog´ıa (MCyT) of Spain (Projects BQU2000-0227
and FEDER 1FD97-0565), the Fundacio´n para la
Investigacio´n Cient´ıfica y Te´cnica (FICYT) de Asturias
(Project PR-01-GE-4) and the EU (COST programme
D12/0025/99). S.E.G.-G. thanks the MCyT for the
award of a Ph.D. grant.
(f) R. Noyori, M. Yamakawa, S. Hashiguchi, J. Org. Chem. 66
(2001) 7931.
[7] For reviews on the chemistry of dimers [{Ru(h6-arene)(m-Cl)Cl}2]
see: (a) H. Le Bozec, D. Touchard, P.H. Dixneuf, Adv.
Organomet. Chem. 29 (1989) 163;
(b) M.A. Bennett, in: E.W. Abel, F.G.A. Stone, G. Wilkinson
(Eds.), Comprehensive Organometallic Chemistry II, vol. 7,
Pergamon Press, Oxford, 1995, p. 549;
(c) M.A. Bennett, Coord. Chem. Rev. 166 (1997) 225.
[8] (a) G. Gritzner, J. Kuta, Pure Appl. Chem. 56 (1984) 461;
(b) N.G. Connelly, W.E. Geiger, Chem. Rev. 96 (1996) 877.
[9] (a) See for example: D. Devanne, P.H. Dixneuf, J. Organomet.
Chem. 390 (1990) 371;
References
[1] For general reviews see: (a) A. Bader, E. Lindner, Coord. Chem.
Rev. 108 (1991) 27;
(b) H. Le Bozec, K. Ouzzine, P.H. Dixneuf, Organometallics 10
(1991) 2768;
(b) C.S. Slone, D.A. Weinberger, C.A. Mirkin, Prog. Inorg.
Chem. 48 (1999) 233.
(c) R. Dussel, D. Pilette, P.H. Dixneuf, W.P. Fehlhammer,
Organometallics 10 (1991) 3287;
[2] V.V. Grushin, Organometallics 20 (2001) 3950 (and references
cited therein).
(d) H. Kucukbay, B. Cetinkaya, S. Guesmi, P. H. Dixneuf,
¨ ¨
Organometallics 15 (1996) 2434;
[3] See for example: (a) V.A. Gilyarov, V.Y. Kovtum, M.I. Kabach-
mich, Izv. Akad. Nauk SSSR, Ser. Khim. 5 (1967) 1159;
(b) K.V. Katti, R.G. Cavell, Inorg. Chem. 28 (1989) 413;
(c) K.V. Katti, R.J. Batchelor, F.W.B. Einstein, R.G. Cavell,
Inorg. Chem. 29 (1990) 808;
(e) J.-F. Mai, Y. Yamamoto, J. Organomet. Chem. 560 (1998)
223;
(f) Y. Yamamoto, H. Nakamura, J.-F. Mai, J. Organomet. Chem.
640 (2001) 10;
(d) R.G. Cavell, R.W. Reed, K.V. Katti, M.S. Balakrishna, P.W.
Collins, V. Mozol, I. Bartz, Phosphorus, Sulfur, Silicon 76 (1993)
9;
(g) R. Bhalla, C.J. Boxwell, S.B. Duckett, P.J. Dyson, D.G.
Humphrey, J.W. Steed, P. Suman, Organometallics 21 (2002) 924;
(h) P. Valerga, M.C. Puerta, D.S. Pandey, J. Organomet. Chem.
648 (2002) 27.
(e) M.W. Avis, M. Goosen, C.J. Elsevier, N. Veldman, H.
Kooijman, A.L. Spek, Inorg. Chim. Acta 264 (1997) 43;
(f) P. Molina, A. Arques, A. Garc´ıa, M.C. Ram´ırez de Arellano,
Tetrahedron Lett. 38 (1997) 7613.
[10] (a) E.T. Singewald, C.S. Slone, C.L. Stern, C.A. Mirkin, G.P.A.
Yap, L.M. Liable-Sands, A.L. Rheingold, J. Am. Chem. Soc. 119
(1997) 3048;
[4] (a) K.V. Katti, R.G. Cavell, Organometallics 7 (1988) 2236;
(b) K.V. Katti, R.G. Cavell, Organometallics 8 (1989) 2147;
(c) K.V. Katti, R.G. Cavell, Inorg. Chem. 28 (1989) 3033;
(d) K.V. Katti, R.G. Cavell, Organometallics 10 (1991) 539;
(e) R.G. Cavell, K.V. Katti, Can. Pat. Appl. CA 2,024,284, 1992;
(f) A. Saravanamuthu, D.M. Ho, M.E. Kerr, C. Fitzgerald,
M.R.M. Bruce, A.E. Bruce, Inorg. Chem. 32 (1993) 2202;
(g) K.V. Katti, B.D. Santarsiero, A.A. Pinkerton, R.G. Cavell,
Inorg. Chem. 32 (1993) 5919;
(b) See also: W.J. Bowyer, J.W. Merket, W.E. Geiger, A.L.
Rheingold, Organometallics 8 (1989) 191.
[11] This feature is also observed in analogous areneꢀ
complexes such as [Ru(h6-1,2,3,4-C6H2Me4)Cl2(PR3)] (PR3ꢂ
PPh3 (5), PMe3 (6)) (see Section 4) which can be also oxidized
at lower potentials (5: E8?ꢂ0.70 V; 6: E8?ꢂ0.44 V) than those of
[Ru(h6-C6Me6)Cl2(PR3)] (PPh3: E8?ꢂ
0.92 V; PMe3: E8?ꢂ0.77
V) 9b.
/phosphine
/
/
/
/
/
[12] The use of AgSbF6 as chloride extractor instead of NaPF6,
previously used in ref [5], allows the formation of cationic species
(h) D.J. Law, R.G. Cavell, J. Mol. Catal. 91 (1994) 175;
(i) D.J. Law, G. Bigam, R.G. Cavell, Can. J. Chem. 73 (1995) 635;
(j) J. Li, R. McDonald, R.G. Cavell, Organometallics 15 (1996)
1033;
4aꢀf in higher yields.
/
[13] See for example: (a) H. Yang, M. Alvarez, N. Lugan, R. Mathieu,
J. Chem. Soc. Chem. Commun. (1995) 1721;
(k) R.W. Reed, B. Santarsiero, R.G. Cavell, Inorg. Chem. 35
(1996) 4292;
(b) Q. Jiang, D. van Plew, S. Murtuza, X. Zhang, Tetrahedron
Lett. 37 (1996) 797;
(l) R.G. Cavell, B. Creed, L. Gelmini, D.J. Law, R. McDonald,
A.R. Sanger, A. Somogyvari, Inorg. Chem. 37 (1998) 757;
(m) P. Molina, A. Arques, A. Garc´ıa, M.C. Ram´ırez de Arellano,
Eur. J. Inorg. Chem. (1998) 1359;
(c) H. Yang, M. Alvarez-Gressier, N. Lugan, R. Mathieu,
Organometallics 16 (1997) 1401;
(d) T. Sammakia, E.L. Stangeland, J. Org. Chem. 62 (1997) 6104;
(e) Y. Nishibayashi, I. Takei, S. Uemura, M. Hidai, Organome-
tallics 18 (1999) 2291;
(n) J. Vicente, A. Arcas, D. Bautista, M.C. Ram´ırez de Arellano,
Organometallics 17 (1998) 4544;
(f) P. Braunstein, C. Graiff, F. Naud, A. Pfaltz, A. Tiripicchio,
Inorg. Chem. 39 (2000) 4468;
(o) R.S. Pandurangi, K.V. Katti, L. Stillwell, C.L. Barnes, J. Am.
Chem. Soc. 120 (1998) 11364;
(p) A. Arques, P. Molina, D. Auno´n, M.J. Vilaplana, M.
˜
(g) P. Braunstein, F. Naud, A. Pfaltz, S.J. Rettig, Organometallics
19 (2000) 2676;
Desamparados Velasco, F. Mart´ınez, D. Bautista, F.J. Lahoz, J.
Organomet. Chem. 598 (2000) 329;
(h) G. Helmchen, A. Pfaltz, Acc. Chem. Res. 33 (2000) 336;
(i) P. Crochet, J. Gimeno, S. Garc´ıa-Granda, J. Borge, Organo-
metallics 20 (2001) 4369;
(q) M. Alajar´ın, C. Lo´pez-Leonardo, P. Llamas-Lorente, Tetra-
hedron Lett. 42 (2001) 605.
[5] V. Cadierno, J. D´ıez, S.E. Garc´ıa-Garrido, S. Garc´ıa-Granda, J.
Gimeno, J. Chem. Soc. Dalton Trans. (2002) 1465.
[6] See for example: (a) G. Zassinovich, G. Mestroni, S. Gladiani,
Chem. Rev. 92 (1992) 1051;
(j) A.M. Maj, K.M. Pietrusiewicz, I. Suisse, F. Agbossou, A.
Mortreux, J. Organomet. Chem. 626 (2001) 157.
[14] (a) C. Standfest-Hauser, C. Slugovc, K. Mereiter, R. Schmid, K.
Kirchner, L. Xiao, W. Weissensteiner, J. Chem. Soc. Dalton
Trans. (2001) 2989;
(b) R. Noyori, S. Hashiguchi, Acc. Chem. Res. 30 (1997) 97;

V. Cadierno et al. / Journal of Organometallic Chemistry 663 (2002) 32ꢀ
/39
39
(b) P. Braunstein, M.D. Fryzuk, F. Naud, S.J. Rettig, J. Chem.
Soc. Dalton Trans. (1999) 589;
chelate ring openning. In fact, 31P{1H}-NMR spectra of the
catalytic reaction mixtures showed, after 15 min, resonances
(c) P. Braunstein, F. Naud, S.J. Rettig, New J. Chem. 25 (2001)
32.
typical of two AB systems at ca. 28 and 4 ppm (2JPP
21 and 1 ppm (2JPP
ꢂ/24 Hz), and
ꢂ/27 Hz), which are consistent with a
[15] Attempts to synthesize hydride derivatives B by reaction of
complexes 4 with one equivalent of NaOH in propan-2-ol failed
obtaining instead complicated mixtures of uncharacterized spe-
cies.
monodentate coordination of the ligand 2 [5].
[17] (a) M.A. Bennett, A.K. Smith, J. Chem. Soc. Dalton Trans.
(1974) 233;
(b) M.A. Bennett, T.-N. Huang, T.W. Matheson, A.K. Smith,
Inorg. Synth. 21 (1982) 74;
(c) J.W. Hull, W.L. Gladfelter, Organometallics 3 (1984) 605.
[16] Alternatively, transformation of A into C could involve inter-
mediate D formed by coordination of cyclohexanone to A via