Mononuclear ruthenium complexes containing two different phosphines in trans position: I. Synthesis and spectroscopic characterization

Article abstract of DOI:10.1016/j.jorganchem.2005.07.100

New mononuclear ruthenium complexes Ru(CO)₂(Y)(Y′)(P ⁿBu₃)[P(p-XC₆H₄)₃] (Y, Y′ = H, CH₃COO; X = CH₃O, CH₃, H, F, Cl), all containing a PⁿBu₃ in trans position to a triarylphosphinic ligand differently substituted in the para position, were synthesized. These ligands were chosen in order to change the basicity of the phosphine in trans to the PⁿBu₃, without relevant steric changes. Spectroscopic data of the new complexes were correlated with the basicity of the triarylphosphines or with the mesomer effect of the substituent in the para position of the aromatic ring. The presence of two different phosphines into a mononuclear ruthenium complex seems an interesting model to study the trans effect for octahedral species.

Full text of DOI:10.1016/j.jorganchem.2005.07.100

Journal of Organometallic Chemistry 690 (2005) 4867–4877
www.elsevier.com/locate/jorganchem
Mononuclear ruthenium complexes containing
two different phosphines in trans position: I. Synthesis
and spectroscopic characterization
*
F. Micoli, L. Salvi, A. Salvini , P. Frediani, C. Giannelli
Department of Organic Chemistry, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Florence, Italy
Received 1 July 2005; received in revised form 26 July 2005; accepted 26 July 2005
Available online 12 September 2005
Abstract
New mononuclear ruthenium complexes Ru(CO)2(Y)(Y0)(PnBu3)[P(p-XC6H4)3] (Y, Y0 = H, CH3COO; X = CH3O, CH3, H, F,
Cl), all containing a PnBu3 in trans position to a triarylphosphinic ligand differently substituted in the para position, were synthe-
sized. These ligands were chosen in order to change the basicity of the phosphine in trans to the PnBu3, without relevant steric
changes. Spectroscopic data of the new complexes were correlated with the basicity of the triarylphosphines or with the mesomer
effect of the substituent in the para position of the aromatic ring. The presence of two different phosphines into a mononuclear ruthe-
nium complex seems an interesting model to study the ‘‘trans effect’’ for octahedral species.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; Mononuclear complexes; Octahedral complexes; trans Effect; Phosphinic ligands
1. Introduction
tion sphere, but also the mobility of the other ligands,
particularly those in trans position.
Recently, we have studied the reaction of the binu-
clear ruthenium carbonylcarboxylato Ru2(CO)4(CH3-
COO)2(PnBu3)2 with acetic acid and we have observed,
through NMR spectroscopy, the formation of a mono-
nuclear specie containing a j1 acetato ligand and a j2
coordinated one, Ru(CO)2(j1-O-CH3COO)(j2-O,O0-
CH3COO)(PnBu3). This complex has been used as
intermediate for the synthesis of Ru(CO)2(CH3COO)2-
(PnBu3)(PPh3), containing two different phosphinic
ligands in trans position [1] (Fig. 1).
The ‘‘trans effect’’ is a well-known phenomenon for
ligand substitution in square-planar complexes of Pt(II)
[2], Rh(I) [3], Pd(II) and Ni(II) [4], while it has been
much less investigated for octahedral complexes [5]. In
particular, the ‘‘trans influence’’ has been well estab-
lished for ruthenium octahedral silyl complexes
[5o,5p,5q,6]. The ‘‘trans effect’’ in octahedral complexes
is analogous to that of square-planar ones. However,
Bersuker [7] reports that the ‘‘trans effect’’ of octahedral
complexes is lower and further it is complicated by the
effect of cis neighbors and steric hindrance.
A ‘‘trans effect’’ may influence the reactivity and the
catalytic activity of a mixed biphosphine-substituted
mononuclear ruthenium complex. For example, in a
process involving a dissociative mechanism, the synergic
effect of trans phosphines would make easier the forma-
tion of a coordinatively unsaturated specie, available for
the activation of reagents and substrates. In fact the
The presence of two different phosphines is an inter-
esting model to study the ‘‘trans effect’’ for octahedral
species. In fact the r-donor and the p-acceptor ability
of a ligand influence its stability in the metal coordina-
*
Corresponding author. Tel.: +39 55 4573455; fax: +39 55 4573531.
E-mail address: antonella.salvini@unifi.it (A. Salvini).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.07.100

4868
F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
PnBu3
Table 2
Steric and electronic properties of the employed phosphinesa
CO
CH3COO
CH3COO
Ru
Ligand
v
pKa
#
CO
P(nBu)3
P(p-CH3OC6H4)3
P(p-CH3C6H4)3
PPh3
5.25
10.50
–
13.25
15.70
16.80
8.43
4.59
3.84
2.73
1.97
1.03
132
145
145
145
145
145
PPh3
Fig. 1. Structure of Ru(CO)2(CH3COO)2(PnBu3)(PPh3).
P(p-FC6H4)3
P(p-ClC6H4)3
a
contemporary presence of the significantly more basic
PnBu3 and of the good leaving ligand PPh3 facilitates
the less basic phosphine dissociation.
See [9d] for the discussion about phosphines basicity values.
To study how the presence of two different phosphi-
nic ligands on the same metal centre affects the reactivity
and the catalytic activity, we have synthesized several
mononuclear ruthenium complexes (Table 1), contain-
ing different para substituted triarylphosphinic ligands
in trans position to the PnBu3 (Fig. 2).
Tolman [8] made a practical and useful separation be-
tween electronic and steric effects, introducing the cone
angle # and the electronic parameter v, as measures of,
respectively, the steric bulk and the electronic properties
of phosphorus ligands.
research, while it is negligible their dependence to steric
effects. The pKa values decrease with enhancement of the
v values (Table 2).
The substituent in the para position of the aromatic
ring gradually modulates the basicity of the triarylphos-
phines, without relevant steric changes. In fact, the
employed triarylphosphines are characterized by the
same cone angle value (#), but show different pKa values
(Table 2).
These para substituted triarylphosphines are useful to
change the electronic contribute of the ligand, without
significant steric variations.
The basicity of the phosphinic ligands has been often
used as a measure of r-donor power of these ligands to-
ward transition metals [9]. In the literature, many studies
are reported about the correlation between basicity of
phosphines and their stereoelectronic effects. Rahman
et al. [10] found a linear relation between pKa values
and v parameters for the triarylphosphines used in our
2. Results and discussion
2.1. Synthesis of Ru(CO)2(CH3COO)2(PnBu3)-
[P(p-XC6H4)3] (1a–1e)
Table 1
Ru(CO)2(Y)(Y0)(PnBu3)[P(p-XC6H4)3] complexes
Ru(CO)2(CH3COO)2(PnBu3)[P(p-XC6H4)3] (1a–1e)
have been synthesized from a tributylphosphine substi-
tuted binuclear ruthenium carbonylcarboxylato com-
plex. Ru2(CO)4(CH3COO)2(PnBu3)2 reacts at 40 ꢁC
with acetic acid [1] giving the unstable specie Ru-
(CO)2(j1-O-CH3COO)(j2-O,O0-CH3COO)(PnBu3), con-
taining one j1 and one j2 acetato ligand (Scheme 1). The
conversion is 100% after 48 h.
Adding an equimolecular amount of a triarylphos-
phine to the solution of this intermediate specie, the
complexes 1a–1e are obtained (Scheme 2) together with
a small amount of the two mononuclear Ru(CO)2-
(CH3COO)2(PnBu3)2 and Ru(CO)2(CH3COO)2[P(p-
XC6H4)3]2 (4a–4e), containing two identical phosphines.
The reaction is carried out at 40 ꢁC, in order to minimize
their formation. The conversion is 100% after 6 h. It is
interesting to observe that a shorter time (2 h) has been
sufficient for the formation of the complex 1a, in agree-
ment with P(p-CH3OC6H4)3 easier coordination to the
ruthenium due to the electron donating power of the
CH3O substituent. A longer reaction time (14 days) is
required to obtain the analogous complex containing
the P(OPh)3 in trans position to the PnBu3, due to phos-
phito less basicity (pKa = ꢀ2).
Code
X
Y
Y0
1a
2a
3a
CH3O
CH3COO
H
H
CH3COO
H
CH3COO
1b
2b
3b
CH3
H
CH3COO
H
H
CH3COO
H
CH3COO
1c
2c
3c
CH3COO
H
H
CH3COO
H
CH3COO
1d
2d
3d
F
CH3COO
H
H
CH3COO
H
CH3COO
1e
2e
3e
Cl
CH3COO
H
H
CH3COO
H
CH3COO
PnBu3
Y'
Y
X = CH3O, CH3, H, F, Cl
Y, Y' = H, CH3COO
CO
CO
P(p-XC6H4)3
Fig. 2. Structure of Ru(CO)2(Y)(Y0)(PnBu3)[P(p-XC6H4)3].
Ru

F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
4869
CH3
H3C
C
CH3
+
C
C
O
O
O
O
O
CH3COO
nBu3P
AcOH, n-heptane
nBu3P
PnBu3
2
Ru
Ru
CO
Ru
O
H2
40 ˚C
CO CO
CO
CO CO
Scheme 1.
Table 3
IR stretching frequencies of carbonyl groupsa
2.2. Spectroscopic characterization of
Ru(CO)2(CH3COO)2(PnBu3)[P(p-XC6H4)3] (1a–1e)
Complex
mCO (cmꢀ1
)
Triarylphosphine pKa
All Ru(CO)2(CH3COO)2(PnBu3)[P(p-XC6H4)3] com-
plexes (1a–1e) have been characterized by IR and multi-
nuclear NMR spectroscopy and the collected data are in
agreement with an octahedral structure containing two
phosphines in trans position, two cis carbonyl groups
and two cis acetato ligands (Fig. 2, Y = Y0 =
CH3COO).
The spectroscopic data have been correlated with the
basicity of the triarylphosphines or with the mesomer ef-
fect of the substituent in the para position of the aro-
matic ring.
1a
1b
1c
1d
1e
2a
2b
2c
2d
2e
2040 (vs) 1976 (vs)
2041 (vs) 1977 (vs)
2042 (vs) 1979 (vs)
2043 (vs) 1980 (vs)
2044 (vs) 1981 (vs)
2002 (s) 1961 (vs)
2003 (s) 1962 (vs)
2005 (s) 1964 (vs)
2007 (s) 1966 (vs)
2008 (s) 1967 (vs)
4.59
3.84
2.73
1.97
1.03
4.59
3.84
2.73
1.97
1.03
4a
4b
4c
4d
4e
a
1942
1943
1947
1950
1953
4.59
3.84
2.73
1.97
1.03
In the IR spectra, the CO stretching frequencies for
the species 1a–1e are similar, nevertheless a slight reduc-
tion of the frequencies has been observed increasing the
triarylphosphine basicity (Table 3).
Solvent: CH2Cl2 for 1a–1e and 4a–4e, C6D6 for 2a–2e.
When the r-donor power of the phosphinic ligand in-
creases, the electron density on the ruthenium enhances
and the backdonation from the metal to the carbonyl
group increases; so the bond order of the CO is reduced.
Increasing the basicity of the P(p-XC6H4)3 the 31P
chemical shift of the coordinated PnBu3 decreases (Table
4). In fact, when the basicity of the P(p-XC6H4)3 en-
hances, the strength of the Ru–PnBu3 bond is weaker,
causing an increase of the phosphorus electron density,
thus a higher shielding, and the PnBu331P d shifts to low-
er frequency. It is interesting to observe that the specie
Ru(CO)2(CH3COO)2(PnBu3)2 shows, in the 31P NMR
spectrum, a signal at 17.4 ppm, in agreement with the
presence of the two more basic ligands PnBu3.
Table 4
31P NMR d of 1a–1e and of free triarylphosphinesa
Complex
d PnBu3
d P(p-XC6H4)3
d Free P(p-XC6H4)3
1a
1d
1e
1b
1c
a
21.7
23.7
24.3
22.7
23.0
26.2
27.1
27.4
27.9
29.2
ꢀ10.7
ꢀ9.6 (d; JPF = 4.1 Hz)
ꢀ9.0
ꢀ8.3
ꢀ5.8
Solvent: C6D6.
to the mesomer effect +M of the substituent in the para
position (CH3O > F > Cl > CH3 > H). In fact, increas-
ing the electron-donating ability of the substituent, the
electron density on the para carbons increases and 31P
d is shifted to lower values.
The 31P chemical shifts (Table 4) of para-substituted
triarylphosphines (free and coordinated) are correlated
The resonance of PPh3 in the complex Ru(CO)2(CH3-
COO)2(PPh3)2 (33.0 ppm) is more deshielded than in the
complex 1c, where the PPh3 is trans to the more basic
PnBu3, in agreement with the stronger ‘‘trans effect’’ of
PnBu3.
Increasing the basicity of the triarylphosphine, the
acetato CH3 d is less shielded (Table 5). This trend is
in agreement with the 1H NMR spectra of the complexes
Ru(CO)2(CH3COO)2(PnBu3)2 and Ru(CO)2(CH3COO)2-
(PPh3)2, having the acetato chemical shifts at 2.25 and
1.62 ppm, respectively.
CH3
C
O
CH3COO
nBu3P
PnBu3
CH3COO
CH3COO
CO
P(p-XC6H4)3
Ru
Ru
O
40 ˚C
CO
P(p-XC6H4)3
CO
CO
X = CH3O (1a), CH3 (1b), H (1c), F (1d), Cl (1e)
Scheme 2.

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F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
Table 5
P(p-XC6H4)3
P(p-XC6H4)3
1H NMR d of 1a–1e acetato groupsa
CO
CH3COO
CH3COO
CO
CH3COO
OC
Ru
Ru
Complex
d
Triarylphosphine pKa
OOCCH3
CO
1a
1b
1c
1d
1e
a
1.99
1.95
1.87
1.85
1.84
4.59
3.84
2.73
1.97
1.03
P(p-XC6H4)3
(a)
P(p-XC6H4)3
(b)
P(p-XC6H4)3
P(p-XC6H4)3
Ru
P(p-XC6H4)3
Solvent: C6D6.
OC
P(p-XC6H4)3
CH3COO
CH3COO
Ru
CH3COO
CO
CO
In the 1H NMR spectra of all complexes, among 6.50
and 8.00 ppm, the most deshielded signal is assigned to
protons in orto position, due to the electron-withdraw-
ing effect of the phosphorus atom. Furthermore, when
phosphorus is coordinated to the metal, there is not elec-
tron delocalization of the phosphorus lone pair on the
orto carbons due to the mesomer effect, as in the free
ligand.
OOCCH3
CO
(d)
(c)
P(p-XC6H4)3
P(p-XC6H4)3
CH3COO
OC
Ru
OOCCH3
CO
(e)
The higher r-donor ability of the phosphine reduces
the electron density on the phosphorus atom which ex-
erts a greater electron-withdrawing effect on the aro-
matic system. Consequently, increasing the basicity of
the phosphine, the orto H d shifts to higher frequencies
(Table 6).
Any correlation was not found between meta H d and
the basicity of the coordinated phosphine P(p-XC6H4)3
(Table 6).
X = CH3O, CH3, H, F, Cl
Fig. 3. Possible structures of 4a–4e.
equivalent acetato ligands; the triplet at higher frequen-
cies than 200 ppm in the 13C NMR spectra may be as-
cribed to the carbon atoms of two equivalent carbonyl
groups coupled with two cis phosphines; the 31P NMR
spectra show only one resonance, in agreement with
the presence of two equivalent phosphines. With the
collected spectroscopic data we are not able to discrim-
inate among the structures (b) or (d) for these
complexes.
The formation of the species Ru(CO)2(CH3-
COO)2[P(p-XC6H4)3]2 (X = CH3, F, Cl) (4b, 4d, 4e) in
the synthesis of Ru(CO)2(CH3COO)2(PnBu3)[P(p-
XC6H4)3] (1b, 1d, 1e) has been evidenced only through
IR and 31P NMR spectroscopy.
2.3. Spectroscopic characterization of
Ru(CO)2(CH3COO)2[P(p-XC6H4)3]2 (4a–4e)
Ru(CO)2(CH3COO)2[P(p-XC6H4)3]2 (4a–4e) com-
plexes were found as by-products in the synthesis
of Ru(CO)2(CH3COO)2(PnBu3)[P(p-XC6H4)3] (1a–1e).
The complexes Ru(CO)2(CH3COO)2[P(p-XC6H4)3]2
(X = CH3O, H) (4a, 4c) were isolated and characterized
through IR and multinuclear NMR spectroscopy.
The elemental analysis confirmed the reported
formulation.
The data collected are in agreement with an octahe-
dral structure. The possible structures (a), (c), (e), re-
ported in Fig. 3, can be ruled out according to the
following considerations: the presence of a single band
in the carbonyl stretching region of the IR spectra is
in agreement with two carbonyl groups in trans position;
the 1H and 13C NMR spectra are in agreement with two
Increasing the triarylphosphine basicity, the CO
stretching frequency decreases (Table 3), also for the
complexes 4a–4e.
The 31P chemical shifts of the triarylphosphines coor-
dinated to the ruthenium (Table 7) have the same trend
observed for the free phosphines (Table 4), in agreement
with a mesomer effect +M of the substituent in the para
position (CH3O > F > Cl > CH3 > H).
Table 7
31P NMR d of 4a–4ea
Table 6
1H NMR d of 1a–1e phosphine aromatic ringsa
Complex
d
Complex
Triarylphosphine pKa
d Ho
d Hm
4a
4b
4c
4d
4e
a
35.5
38.4
39.0
37.5
38.3
1a
1b
1d
1e
a
4.59
3.84
1.97
1.03
7.96
7.94
7.73
7.64
6.77
6.99
6.76
7.07
Solvent: C6D6.
Solvent: C6D6.

F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
4871
2.4. Synthesis of RuH2(CO)2(PnBu3)[P(p-XC6H4)3]
(2a–2e)
complexes containing two identical phosphines Ru
(CO)2(CH3COO)2(PnBu3)2 [11] and Ru(CO)2(CH3-
COO)2(PPh3)2 [12]: lower temperatures and shorter
times are needed for 1a–1e transformation into the
corresponding 2a–2e.
Ru(CO)2(CH3COO)2(PnBu3)[P(p-XC6H4)3] (1a–1e)
have been quantitatively transformed into the corre-
sponding dihydride RuH2(CO)2(PnBu3)[P(p-XC6H4)3]
(2a–2e), according to Scheme 3. These reactions have
been performed into an autoclave, with 100 bar of
hydrogen, at 60 ꢁC for 14 h (2a, 2b, 2d, 2e) or at 40
ꢁC for 16 h (2c).
The formation of the dihydride complexes from the
diacetato species with hydrogen is reversible, so the reac-
tion is carried out in the presence of anhydrous sodium
carbonate to neutralize the free acetic acid and to shift
the equilibrium.
The reaction conditions have been chosen in order to
have the complete conversion of 1a–1e, minimizing the
concomitant phosphine redistribution to give bis-tribut-
ylphosphino and bis-triarylphosphino diacetato and
dihydrido complexes.
The presence of two different phosphines in the coor-
dination sphere of the metal has a positive effect on
hydrogen activation. In fact these diacetato complexes
are more reactive with hydrogen than the analogous
This behavior suggests the formation of dihydride
complexes through the dissociation of triarylphosphine,
then the formation of a dihydrogen complex, that elim-
inates acetic acid and finally the recoordination of the
phosphinic ligand (Scheme 4). The formation of the
dihydride complex is preceded by the formation of a
ruthenium hydroacetate. The monohydrido complex
1
has been evidenced in the 31P and H NMR spectra
when the reaction with hydrogen is not completed.
RuH(CO)2(CH3COO)(PnBu3)[P(p-CH3OC6H4)3] (3a)
and RuH(CO)2(CH3COO)(PnBu3)(PPh3) (3c), likewise
the species RuH(CO)2(CH3COO)(PnBu3)2 [13] and
RuH(CO)2(CH3COO)(PPh3)2 [14], were synthesized
and characterized.
For a better characterization 3a, 3c (Fig. 2, Y = H,
Y0 = CH3COO), intermediates of the reaction between
1a, 1c and hydrogen, have been synthesized by reaction
of the RuH2(CO)2(PnBu3)[P(p-XC6H4)3] (2a, 2c) with
acetic acid (Scheme 5).
H2, Na2CO3
CH3COONa
Ru(CO)2(CH3COO)2(PnBu3)[P(p-XC6H4)3]
RuH2(CO)2(PnBu3)[P(p-XC6H4)3]
X = CH3O, CH3, H, F, Cl
Scheme 3.
PnBu3
P(p-XC6H4)3
PnBu3
H2
OOCCH3
OOCCH3
OOCCH3
OC
OC
OC
OC
Ru(CO)2(CH3COO)2(PnBu3)
Ru
Ru
OOCCH3
H
H
P(p-XC6H4)3
1a-1e
PnBu3
CH3COOH
P(p-XC6H4)3
OOCCH3
OC
OC
Ru
Ru(H)(CO)2(CH3COO)(PnBu3)
H
P(p-XC6H4)3
3a-3e
H2
H2
P(p-XC6H4)3
PnBu3
P(p-XC6H4)3
CH3COOH
PnBu3
H
OC
OC
OC
OC
OOCCH3
H
Ru(H)2(CO)2(PnBu3)
Ru
Ru
H
H
H
P(p-XC6H4)3
2a-2e
Scheme 4.

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F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
RuH2(CO)2(PnBu3)[P(p-XC6H4)3] + CH3COOH
RuH(CO)2(CH3COO)(PnBu3)[P(p-XC6H4)3] + H2
Scheme 5.
2.5. Spectroscopic characterization of
RuH2(CO)2(PnBu3)[P(p-XC6H4)3] (2a–2e)
Table 9
1H NMR d of 2a–2e hydridesa
Complex
Triarylphosphine pKa
d
The complexes RuH2(CO)2(PnBu3)[P(p-XC6H4)3]
(2a–2e) have been characterized through IR and multi-
nuclear NMR spectroscopy and the collected data are
in agreement with an octahedral structure containing
the PnBu3 in trans position to the P(p-XC6H4)3, two
cis carbonyl groups and two cis hydridic ligands
(Fig. 2, Y = Y0 = H).
The CO stretching frequencies, in the IR spectra of
the dihydride complexes, have values correlated with
P(p-XC6H4)3 pKa (Table 3). The same explanation re-
ported for the 1a–1e CO stretching frequencies trend
may be claimed.
2a
2b
2c
2d
2e
a
4.59
3.8
2.73
1.97
1.03
ꢀ6.87
ꢀ6.93
ꢀ7.04
ꢀ7.17
ꢀ7.27
Solvent: C6D6.
are at ꢀ7.73 and ꢀ6.35 ppm, respectively, in agreement
with the phosphine basicity.
3. Summary
31P NMR d trend of the two phosphinic ligands is dif-
ferent from that observed for the corresponding acetato
complexes, showing as the distribution of electronic den-
sity in the complexes is the result of the global effect of
all ligands.
New mononuclear ruthenium complexes Ru
(CO)2(Y)(Y0)(PnBu3)[P(p-XC6H4)3] (Y, Y0 = H, CH3-
COO; X = CH3O, CH3, H, F, Cl), containing two
different phosphinic ligands in trans position, have been
synthesized and spectroscopically characterized. These
complexes contain, in trans position to the PnBu3, differ-
ent para substituted triarylphosphinic ligands, having
the same cone angle value, but different pKa values.
The electronic properties of these complexes change
gradually, without relevant steric changes, offering an
interesting model to study the ‘‘trans effect’’ in octahe-
dral species. The presence of two different phosphines
on the same metal centre affects the reactivity with
hydrogen of these mixed biphosphine-substituted ruthe-
nium complexes, that may be ascribed to ‘‘trans effect’’.
In fact the complexes 1a–1e react with hydrogen at low-
er temperatures and with shorter times with respect to
the analogous Ru(CO)2(CH3COO)2(PnBu3)2 and
Ru(CO)2(CH3COO)2(PPh3)2.
The spectroscopic properties of these complexes
Ru(CO)2(Y)(Y0)(PnBu3)[P(p-XC6H4)3] have been corre-
lated with the triarylphosphines basicity or with the me-
somer effect of the para substituent of the aromatic ring.
The collected data indicate that the phosphines ‘‘trans
effect’’ is evident above all in the acetato 1a–1e. This
effect may be correlated with the reactivity and the cat-
alytic activity of these complexes.
In fact the presence of different P(p-XC6H4)3 in trans
does not seem to have any influence on d 31P values of
the PnBu3, while chemical shifts of the P(p-XC6H4)3 in-
crease as the basicity of the phosphine decreases, except
for PPh3 (2c), that shows highest value (Table 8).
Spectroscopic data seem to indicate that the phos-
phines ‘‘trans effect’’ is more evident in the acetato com-
plexes 1a–1e that in the dihydride 2a–2e. It is known
that in octahedral complexes the ‘‘trans effect’’ can be
complicated by the influence of cis neighbors and steric
hindrance [7]. The ‘‘trans influence’’ of a ligand depends
not only upon the nature and properties of the ligand it-
self but by the metal, its oxidation state, the other li-
gands and the degree of coordination of the metal.
Analogous considerations rise from the analysis of the
1H NMR spectra. The chemical shifts of the hydrides 2a–
2e are among ꢀ7.73 and ꢀ6.35 ppm and, increasing the
r-donor power of the P(p-XC6H4)3, the resonance of the
hydride shifts to higher frequencies (Table 9). This trend
is unexpected; in fact in 1H NMR spectra of RuH2-
(CO)2(PnBu3)2 and RuH2(CO)2(PPh3)2, the hydride d
Table 8
31P NMR d of 2a–2ea
4. Experimental
Complex
d PnBu3
d P(p-XC6H4)3
Triarylphosphine pKa
2a
2b
2c
2d
2e
a
35.3
35.5
35.6
35.2
35.4
49.8
52.4
55.6
53.3
54.7
4.59
3.84
2.73
1.97
1.03
4.1. Materials
Ru2(CO)4(CH3COO)2(PnBu3)2
according to the procedure reported by Crooks et al.
[15].
was
synthesised
Solvent: C6D6.

F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
4873
n-Hexane (95%), n-heptane (99%), methylene chlo-
ride (99.9%), n-pentane (99%), C6D6 (99.8%), sodium
carbonate (99.5%) were reagent grade and used without
further purification.
Acetic acid was distilled under nitrogen prior to use
(b.p. 118 ꢁC).
Triphenylphosphine (98%), tris(4-methoxyphenyl)-
phosphine (95%), tris(4-fluorophenyl)phosphine (99%),
tris(4-chlorophenyl)phosphine (97%) and tris(4-methyl-
phenyl)phosphine (98%) were used without further
purification.
O0-CH3COO), 174.5 (s, j1-O-CH3COO), 24.9 (m,
CH2CH2P), 24.3 (s, CH3CH2), 24.1 (m, CH2P), 23.5
(s, j1-O-CH3COO), 20.1 (s, j2-O,O0-CH3COO), 13.4
(s, CH3CH2). 31P{1H} NMR (C6D6, 121.421 MHz): d
44.4 (43.5 in the presence of acetic acid). IR (n-heptane)
2064 (s), 1999 (vs), 1579 (w), 1517 (vw) cmꢀ1 (spectrum
recorded in the presence of acetic acid).
4.3.2. Ru(CO)2(CH3COO)2(PnBu3)[P(p-CH3O-
C6H4)3] (1a)
350.96 mg of tris(4-methoxyphenyl)phosphine (0.996
mmol) were added to the solution of [Ru(CO)2(j1-O-
CH3COO)(j2-O,O0-CH3COO)(PnBu3)] (0.996 mmol),
in acetic acid (1.8 mL) and n-heptane (40 mL).
The solution was stirred and heated at 40 ꢁC, for 2 h.
A pale yellow solid in small amount was formed. This
solid was filtered, washed with n-heptane, dried and
characterized as Ru(CO)2(CH3COO)2[P(p-CH3OC6-
H4)3]2 (4a).
The washing n-heptane was combined with the color-
less solution; the solvent was distilled under reduced
pressure (temperature lower than 40 ꢁC). The oily resi-
due was dissolved in CH2Cl2, then n-heptane was added.
The solution was concentrated by bubbling nitrogen and
the complex crystallized by cooling to ꢀ20 ꢁC. The
white solid was filtered, washed with n-pentane and
dried under vacuum (639 mg; 0.77 mmol; yield 77.3%).
The mother liquor contained Ru(CO)2(CH3COO)2-
(PnBu3)2.
4.2. Instruments
IR spectra were recorded on a FT-IR Perkin–Elmer
Spectrum BX model, using the Spectrum v. 3.02.02 pro-
gram. The solutions were analyzed using KBr or CaF2
cells having 0.1 mm path.
1H NMR and 1H NMR COSY spectra were recorded
at 399.92 MHz on a Varian Mercury 400 or at 199.985
MHz on a Varian VXR 200, using solvent residual peak
as reference. 13C NMR spectra were collected at 100.57
MHz on a Varian Mercury 400 and at 50.286 MHz on a
Varian VXR 200, using solvent residual peak as refer-
ence. 31P NMR spectra were registered at 121.421
MHz on a Varian VXR 300, using H3PO4 (85%) as
external standard: downfield values were taken as posi-
tive. All 13C and 31P NMR spectra were acquired using
a broad band decoupler. The solvent was choosen in or-
der to avoid the overlap between the solvent residual
peak and complex signals.
Anal. Calc. for C39H54O9P2Ru (MW = 829.863 g
molꢀ1): C, 56.45; H, 6.56. Found: C, 56.51; H, 6.50%.
1
Elemental analyses were performed with a Perkin–
Elmer 2400 Series II CHNS/O analyzer.
NMR and IR data for 1a: H NMR (C6D6, 399.92
MHz): d 7.96 (m, 6H, Ho, P(p-CH3OC6H4)3), 6.77 (m,
6H, Hm, P(p-CH3OC6H4)3), 3.17 (s, 9H, CH3O), 1.99
(s, 6H, CH3COO), 1.97 (m, 6H, CH2P), 1.52 (m, 6H,
CH2CH2P), 1.28 (pq, JHH = 7.3 Hz, 6H, CH3CH2),
0.85 (t, JHH = 7.3 Hz, 9H, CH3CH2). 13C{1H} NMR
(CDCl3, 100.57 MHz): d 197.8 (pt, JCP = 11.4 Hz,
CO), 176.6 (s, CH3COO), 161.1 (d, JCP = 2.1 Hz, Cp,
P(p-CH3OC6H4)3), 135.7 (dd, JCP = 11.5 Hz, JCP = 0.9
Hz, Co, P(p-CH3OC6H4)3), 122.1 (dd, JCP = 44.5 Hz,
JCP = 5.1 Hz, Ci, P(p-CH3OC6H4)3), 113.8 (d,
JCP = 10.4 Hz, Cm, P(p-CH3OC6H4)3), 55.2 (s, CH3O),
25.0 (d, JCP = 3.5 Hz,CH2CH2P), 24.4 (d, JCP = 12.3
Hz, CH3CH2), 23.6 (dd, JCP = 23.5 Hz, JCP = 3.3 Hz,
CH2P), 13.7 (s, CH3CH2), 23.1 (s, CH3COO). 31P{1H}
NMR (C6D6, 121.421 MHz): d 26.8 (A part of an AB
spin system, JPP = 322.3 Hz, 1P, P(p-CH3OC6H4)3),
21.6 (B part of an AB spin system, JPP = 322.3 Hz,
1P, PnBu3). IR (CH2Cl2) 2040 (vs), 1976 (vs), 1595 (s),
4.3. Synthetic procedure
All reactions and manipulations were performed un-
der dry nitrogen by the Schlenk tube technique.
4.3.1. [Ru(CO)2(j1-O-CH3COO)(j2-O,O0-CH3COO)-
(PnBu3)]
A n-heptane (40 mL) solution of Ru2(CO)4(CH3-
COO)2(PnBu3)2 (0.4165 g; 0.498 mmol) and acetic acid
(1.8 mL, 31.5 mmol) was stirred at 40 ꢁC. The reaction
mixture became colorless and the conversion was full
after 48 h.
The new specie [1] was unstable in absence of acetic
acid, even under nitrogen, so the n-heptane solution
was used immediately for the subsequent synthesis of
the mixed complexes.
NMR and IR data for [Ru(CO)2(j1-O-CH3COO)-
1570 (w) cmꢀ1
.
(j2-O,O0-CH3COO)(PnBu3)]: H NMR (C6D6, 199.985
1
MHz): d 2.06 (s broad, 6H, CH3COO), 1.63 (m, 6H,
CH2P), 1.30 (m, 6H, CH2CH2P), 1.16 (m, 6H,
CH3CH2), 0.77 (m, 9H, CH3CH2). 13C{1H} NMR
(C6D6, 50.286 MHz): d 195.9 (m, CO), 183.0 (s, j2-O,
4.3.3. Ru(CO)2(CH3COO)2(PnBu3)[P(p-CH3C6H4)3]
(1b)
303.2 mg of tris(4-methylphenyl)phosphine (0.996
mmol) were added to a solution of [Ru(CO)2(j1-O-

4874
F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
CH3COO)(j2-O,O0-CH3COO)(PnBu3)] (0.996 mmol) in
acetic acid (1.8 mL) and n-heptane (40 mL). The solu-
tion was stirred and heated at 40 ꢁC, for 6 h.
filtered, washed with n-heptane, dried and identified as
Ru(CO)2(CH3COO)2(PPh3)2 (4c).
The washing n-heptane was combined with the pale
yellow solution; the solvent and acetic acid were distilled
under reduced pressure (temperature lower than 40 ꢁC).
n-Heptane was added to the oily residue, at room tem-
perature, and the formation of a white solid (1c) was ob-
served. This product was filtered, washed with n-pentane
and dried under vacuum (321.7 mg; 0.435 mmol).
The mother liquor and the washing n-heptane solu-
tion were concentrated under vacuum and other 198
mg of 1c were collected by filtration (total yield 70.6%).
The mother liquor and the washing n-heptane, ana-
lyzed through IR and multinuclear NMR spectroscopy,
contain Ru(CO)2(CH3COO)2(PnBu3)2.
The solvent and the acetic acid were distilled under
reduced pressure (temperature lower than 40 ꢁC). The
yellow oily residue was dissolved in CH2Cl2 and n-hep-
tane was added. This solution was concentrated by bub-
bling nitrogen and the complex was crystallized by
cooling to ꢀ20 ꢁC. A white solid product was filtered,
washed with n-pentane and dried under vacuum, obtain-
ing 778.7 mg of 1b, impure for Ru(CO)2(CH3-
COO)2[P(p-CH3C6H4)3]2 (4b).
The solid was purified by several extractions with n-
hexane, under nitrogen, at 40 ꢁC. After each extraction
the yellow solution was separated by filtration, under in-
ert atmosphere. The n-hexane solutions were collected,
cooled to ꢀ20 ꢁC, and the white crystals (1b) were fil-
tered, washed with n-pentane and dried under vacuum
(389.4 mg; 0.50 mmol; yield 50.2%).
Anal. Calc. for C36H48O6P2Ru (MW = 739.79 g
molꢀ1): C, 58.45; H, 6.54. Found: C, 58.36; H, 6.54%.
1
NMR and IR data for 1c: H NMR (C6D6, 399.92
MHz): d 7.96 (m, 6H, Ho, PPh3), 7.10 (m, 6H, Hm,
PPh3), 7.02 (m, 3H, Hp, PPh3), 1.94 (m, 6H, CH2P),
1.88 (s, 6H, CH3COO), 1.49 (m, 6H, CH2CH2P), 1.24
(q, JHH = 7.3 Hz, 6H, CH3CH2), 0.82 (t, JHH = 7.3
Hz, 9H, CH3CH2). 13C{1H} NMR (CDCl3, 100.57
MHz): d 197.6 (dd, JCP = 12.2 Hz, JCP = 10.5 Hz,
CO), 176.6 (s, CH3COO), 134.2 (d, JCP = 10.2 Hz, Co,
PPh3), 130.3 (dd, JCP = 40.7 Hz, JCP = 3.2 Hz, Ci,
PPh3), 130.3 (d, JCP = 2.2 Hz, Cp, PPh3), 128.2 (d,
JCP = 9.6 Hz, Cm, PPh3), 25.0 (d, JCP = 3.7 Hz,
CH2CH2P), 24.4 (d, JCP = 12.6 Hz, CH3CH2), 23.6
(dd, JCP = 24.6 Hz, JCP = 2.7 Hz, CH2P), 23.0 (s,
CH3COO), 13.6 (s, CH3CH2). 31P{1H} NMR (C6D6,
121.421 MHz): d 29.7 (A part of an AB spin system,
JPP = 317.4 Hz, 1P, PPh3), 23.0 (B part of an AB spin
system, JPP = 317.4 Hz, 1P, PnBu3). IR (n-heptane)
Further, 194.3 mg of complex 1b was recovered by
cooling to ꢀ20 ꢁC the concentrated mother liquor, with
a total yield of 74.9%.
Anal. Calc. for C39H54O6P2Ru (MW = 781.87 g
molꢀ1): C, 59.91; H, 6.96. Found: C, 60.30; H, 6.97%.
1
NMR and IR data for 1b: H NMR (C6D6, 399.92
MHz): d 7.94 (m, 6H, Ho, P(p-CH3C6H4)3), 6.99 (m,
6H, Hm, P(p-CH3C6H4)3), 1.95 (m, 21H, P(p-
CH3C6H4)3, CH2P, CH3COO), 1.53 (m, 6H,
CH2CH2P), 1.28 (m, 6H, CH3CH2), 0.86 (m, 9H,
1
CH3CH2). H NMR (CDCl3, 399.92 MHz): d 7.94 (m,
6H, Ho, P(p-CH3C6H4)3), 6.99 (m, 6H, Hm, P(p-
CH3C6H4)3), 2.40 (s, 9H, P(p-CH3C6H4)3), 1.92 (m,
6H, CH2P), 1.56 (s, CH3COO), 1.51 (m, 6H,
CH2CH2P), 1.42 (m, 6H, CH3CH2), 0.95 (t, JHH = 7.2
Hz, 9H, CH3CH2). 13C{1H} NMR (CDCl3, 100.57
MHz): 197.7 (pt, JCP = 11.3 Hz, CO), d 176.5 (s,
CH3COO), 140.3 (d, JCP = 1.6 Hz, Cp, P(p-CH3C6H4)3),
134.1 (d, JCP = 10.3 Hz, Co, P(p-CH3C6H4)3), 128.9 (d,
JCP = 9.9 Hz, Cm, P(p-CH3C6H4)3), 127.3 (dd,
JCP = 42.1 Hz, JCP = 4.0 Hz, Ci, P(p-CH3C6H4)3), 25.0
(d, JCP = 3.5 Hz, CH2CH2P), 24.4 (d, JCP = 12.4 Hz,
CH3CH2), 23.6 (dd, JCP = 24.0 Hz, JCP = 2.8 Hz,
CH2P), 23.0 (s, CH3COO), 21.4 (s, P(p-CH3C6H4)3),
13.7 (s, CH3CH2). 31P{1H} NMR (C6D6, 121.421
MHz): d 28.1 (A part of an AB spin system,
JPP = 319.8 Hz, 1P, P(p-CH3C6H4)3), 22.3 (B part of
an AB spin system, JPP = 319.8 Hz, 1P, PnBu3). IR
2044 (vs), 1982 (vs), 1624 (m) cmꢀ1
.
4.3.5. Ru(CO)2(CH3COO)2(PnBu3)[P(p-FC6H4)3]
(1d)
315 mg of tris(4-fluorophenyl)phosphine (0.996
mmol) were added to a solution of [Ru(CO)2(j1-O-
CH3COO)(j2-O,O0-CH3COO)(PnBu3)] (0.996 mmol) in
acetic acid (1.8 mL) and n-heptane (40 mL). The solu-
tion was stirred and heated at 40 ꢁC, for 6 h.
The solvent and the acetic acid were distilled under
reduced pressure (temperature lower than 40 ꢁC); the
yellow oily residue was dissolved in CH2Cl2 and n-hep-
tane was added. The solution was concentrated by bub-
bling nitrogen, at room temperature. The formed pale
yellow solid was filtered, washed with n-pentane and
dried under vacuum, obtaining 537.6 mg of 1d, impure
for Ru(CO)2(CH3COO)2[P(p-FC6H4)3]2 (4d).
The solid was purified by several extractions with n-
hexane, under nitrogen, at 40 ꢁC. After each extraction
the yellow solution was separated by hot filtration,
under inert atmosphere, from the residual white solid
Ru(CO)2(CH3COO)2[P(p-FC6H4)3]2 (4d).
(CH2Cl2) 2041 (vs), 1977 (vs), 1598 (m) cmꢀ1
.
4.3.4. Ru(CO)2(CH3COO)2(PnBu3)(PPh3) (1c)
261 mg of triphenylphosphine (0.996 mmol) were
added to a solution of [Ru(CO)2(j1-O-CH3COO)(j2-
O,O0-CH3COO)(PnBu3)] (0.996 mmol), in acetic acid
(1.8 mL) and n-heptane (40 mL).
The solution was stirred and heated at 40 ꢁC, for 6 h.
A small amount of a white solid was formed and it was

F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
4875
The n-hexane solutions collected were cooled to ꢀ20
ꢁC and a white solid was crystallized (1d), filtered,
washed with n-pentane and dried under vacuum (423.1
mg; 0.533 mmol; yield 53.5%).
P(p-ClC6H4)3), 128.9 (d, JCP = 9.7 Hz, Cm, P(p-
ClC6H4)3), 128.3 (dd, JCP = 39.2 Hz, JCP = 5.4 Hz, Ci,
P(p-ClC6H4)3), 25.0 (d, JCP = 3.4 Hz, CH2CH2P), 24.4
(d, JCP = 13.1 Hz, CH3CH2), 23.6 (dd, JCP = 23.9 Hz,
JCP = 4.0 Hz, CH2P), 23.1 (s, CH3COO), 13.6 (s,
CH3CH2). 31P{1H} NMR (C6D6, 121.421 MHz): d
27.8 (A part of an AB spin system, JPP = 318.6 Hz,
1P, [P(p-ClC6H4)3]), 23.7 (B part of an AB spin system,
JPP = 318.6 Hz, 1P, PnBu3). IR (CH2Cl2) 2044 (vs), 1981
Anal. Calc. for C36H45O6P2F3Ru (MW = 793.76 g
molꢀ1): C, 54.47; H, 5.71. Found: C, 54.42; H, 6.03%.
1
NMR and IR data for 1d: H NMR (C6D6, 399.92
MHz): d 7.73 (m, 6H, Ho, P(p-FC6H4)3), 6.76 (m, 6H,
Hm, P(p-FC6H4)3), 1.89 (m, 6H, CH2P), 1.85 (s, 6H,
CH3COO), 1.45 (m, 6H, CH2CH2P), 1.25 (q,
JHH = 7.3 Hz, 6H, CH3CH2), 0.84 (t, JHH = 7.3 Hz,
9H, CH3CH2). 13C{1H} NMR (CDCl3, 100.57 MHz):
d 197.3 (pt, JCP = 11.4 Hz, CO), 176.6 (s, CH3COO),
164.2 (dd, JCF = 252.8 Hz, JCP = 2.0 Hz, Cp, P(p-
FC6H4)3), 136.3 (ddd, JCP = 11.4 Hz, JCF = 8.5 Hz,
JCP = 1.2 Hz, Co, P(p-FC6H4)3), 125.9 (ddd,
JCP = 40.5 Hz, JCF = 5.3 Hz, JCP = 3.6 Hz, Ci, P(p-
FC6H4)3), 115.8 (dd, JCF = 21.2 Hz, JCP = 10.3 Hz,
Cm, P(p-FC6H4)3), 25.0 (d, JCP = 3.3 Hz, CH2CH2P),
24.4 (d, JCP = 12.5 Hz, CH3CH2), 23.6 (dd, JCP = 23.8
Hz, JCP = 3.9 Hz, CH2P), 23.0 (s, CH3COO), 13.6 (s,
CH3CH2). 31P{1H} NMR (C6D6, 121.421 MHz): d
27.4 (A part of an AB spin system, JPP = 321.1 Hz,
1P, P(p-FC6H4)3), 23.2 (B part of an AB spin system,
JPP = 321.1 Hz, 1P, PnBu3). IR (CH2Cl2) 2043 (vs),
(vs), 1597 (m) cmꢀ1
.
4.3.7. Ru(CO)2(CH3COO)2[P(p-XC6H4)3]2
[X = CH3O, CH3, H, F, Cl] (4a–4e)
All complexes 4a–4e have been obtained as by-prod-
ucts in the synthesis of the corresponding 1a–1e
complexes.
Compounds 4a (59 mg) and 4c (56 mg) are insoluble
in acetic acid and n-heptane and are separated from the
reaction mixture by filtration under nitrogen. They are
purified by washing with n-heptane.
Anal. Calc. for C48H48O12P2Ru (4a) (MW = 979.92 g
molꢀ1): C, 58.83; H, 4.94. Found: C, 59.17; H, 5.28%.
1
NMR and IR data for 4a: H NMR (C6D6, 399.92
MHz): d 7.89 (m, 12H, Ho, P(p-CH3OC6H4)3), 6.78
(m, 12H, Hm, P(p-CH3OC6H4)3), 3.18 (s, 18H, CH3O),
1.23 (s, 6H, CH3COO). 13C{1H} NMR (C6D6, 100.57
MHz): d 209.2 (t, JCP = 13.2 Hz, CO), 182.2 (s,
CH3COO), 162.5 (s, Cp, P(p-CH3OC6H4)3), 137.8 (m,
Co, P(p-CH3OC6H4)3), 123.7 (t, JCP = 24.2 Hz, Ci,
P(p-CH3OC6H4)3), 115.0 (m, Cm, P(p-CH3OC6H4)3),
55.6 (s, CH3O), 23.6 (s, CH3COO). 31P{1H} NMR
(C6D6, 121.421 MHz): d 35.5. IR (CH2Cl2) 1942 (s),
1980 (vs), 1592 (s) cmꢀ1
.
4.3.6. Ru(CO)2(CH3COO)2(PnBu3)[P(p-ClC6H4)3]
(1e)
364.17 mg of tris(4-chlorophenyl)phosphine (0.996
mmol) were added to a solution of [Ru(CO)2(j1-O-
CH3COO)(j2-O,O0-CH3COO)(PnBu3)] (0.996 mmol) in
acetic acid (1.8 mL) and n-heptane (40 mL). The solu-
tion was stirred and heated at 40 ꢁC, for 6 h.
The solvent and the acetic acid were distilled under
reduced pressure (temperature lower than 40 ꢁC). The
oily residue was dissolved in CH2Cl2 and n-heptane
was added. The solution was concentrated by bubbling
nitrogen and cooled to ꢀ20 ꢁC. The white precipitate
was filtered, washed with cold n-pentane and dried un-
der vacuum. 614.3 mg of 1e, impure for Ru(CO)2(CH3-
COO)2[P(p-ClC6H4)3]2 (4e), were obtained. The product
was purified by an other crystallization from CH2Cl2/n-
heptane at ꢀ20 ꢁC, obtaining 528 mg of 1e (yield
62.9%).
1594 (vs), 1569 (m) cmꢀ1
.
Anal. Calc. for C42H36O6P2Ru (4c) (MW = 799.76 g
molꢀ1): C, 63.08; H, 4.54. Found: C, 62.78; H, 4.52%.
NMR and IR data for 4c: 1H NMR (CD2Cl2, 399.92
MHz): d 7.50 (m, 30H, PPh3), 1.50 (s, 6H, CH3COO).
13C{1H} NMR (CD2Cl2, 100.57 MHz): d 207.6 (t,
JCP = 13.9 Hz, CO), 181.6 (s, CH3COO), 135.0 (m, Co,
PPh3), 130.5 (m, Ci, Cp, PPh3), 128.4 (m, Cm, PPh3),
22.2 (s, CH3COO). 31P{1H} NMR (CD2Cl2, 121.421
MHz): d 40.9. IR (CH2Cl2) 1947 (s), 1620 (w), 1603
(w) cmꢀ1
.
Compounds 4b (62 mg) and 4d (105 mg) have been
obtained in the synthesis of the corresponding 1b and
1d removing the mixed complexes by several extractions
with n-hexane, under nitrogen, at 40 ꢁC. The solid resi-
due was separated by filtration, washed with n-pentane.
NMR and IR data for 4b: 31P{1H} NMR (C6D6,
Anal. Calc. for C36H45O6P2Cl3Ru (MW = 843.13 g
molꢀ1): C, 51.28; H, 5.38. Found: C, 51.55; H, 5.19%.
1
NMR and IR data for 1e: H NMR (C6D6, 399.92
MHz): d 7.64 (m, 6H, Ho, P(p-ClC6H4)3), 7.07 (m, 6H,
Hm, P(p-ClC6H4)3), 1.87 (m, 6H, CH2P), 1.84 (s, 6H,
CH3COO), 1.43 (m, 6H, CH2CH2P), 1.23 (pq,
JHH = 7.3 Hz, 6H, CH3CH2), 0.83 (t, JHH = 7.3 Hz,
9H, CH3CH2). 13C{1H} NMR (CDCl3, 100.57 MHz):
d 197.1 (dd, JCP = 11.9 Hz, JCP = 10.3 Hz, CO), 176.7
(s, CH3COO), 137.4 (d, JCP = 2.5 Hz, Cp, P(p-
ClC6H4)3), 135.3 (dd, JCP = 10.6 Hz, JCP = 1.7 Hz, Co,
121.421 MHz): d 38.4. IR (CH2Cl2) 1944 (s) cmꢀ1
.
NMR and IR data for 4d: 31P{1H} NMR (C6D6,
121.421 MHz): d 37.5. IR (CH2Cl2) 1950 (s), 1591 (vs),
1497 (vs) cmꢀ1
.
Compound 4e (100.2 mg) was collected from the
mother liquor after recrystallization of 1e from
CH2Cl2/n-heptane at ꢀ20 ꢁC.

4876
F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
NMR and IR data for 4e: 31P{1H} NMR (C6D6,
121.421 MHz): d 38.3. IR (CH2Cl2) 1953 (s) cmꢀ1
MHz): d 52.6 (A part of an AB spin system,
JPP = 213.8 Hz, 1P, P(p-CH3C6H4)3), 35.5 (B part of
an AB spin system, JPP = 213.8 Hz, PnBu3, 1P). IR
.
4.3.8. RuH2(CO)2(PnBu3)[P(p-XC6H4)3] [X = CH3O,
CH3, H, F, Cl] (2a–2e)
These compounds were synthesized using a modifica-
tion to the procedure reported by Salvini et al. [16] for
RuH2(CO)2(PnBu3)2.
(C6D6) 2036 (d), 2003 (w), 1962 (vs) cmꢀ1
.
1
NMR and IR data for 2c: H NMR (C6D6, 199.985
MHz): d 7.85 (m, 6H, Ho, PPh3), 7.10 (m, 9H, Hp, Hm,
PPh3), 1.64 (m, 12H, CH2CH2P), 1.31 (q, JHH = 7.8
Hz, 6H, CH3CH2), 0.87 (t, JHH = 7.8 Hz, 9H,
CH3CH2), ꢀ7.04 (t, JHP = 23.9 Hz, 2H, HRu).
13C{1H} NMR (C6D6, 50.286 MHz): d 203.6 (pt,
JCP = 8.0 Hz, CO) [the Cp signal is overlapped with
the solvent peak], 135.5 (m, Ci, PPh3), 135.0 (m, Co,
PPh3), 130.4 (m, Cm, PPh3), 33.2 (d, CH2P, JCP = 27.8
Hz), 27.4 (s, CH2CH2P), 25.4 (d, CH3CH2, JCP = 12.8
Hz), 14.8 (s, CH3CH2). 31P{1H} NMR (C6D6, 121.421
MHz): d 55.6 (A part of an AB spin system,
JPP = 213.6 Hz, 1P, PPh3), 35.6 (B part of an AB spin
system, JPP = 213.6 Hz, 1P, PnBu3). IR (C6D6) 2036
In a glass vial 1.50 · 10ꢀ5 mol of Ru(CO)2(CH3-
COO)2(PnBu3)[P(p-XC6H4)3] (1a–1e) and 150 mg of so-
dium carbonate were introduced. The vial was inserted
in a stainless steel autoclave under nitrogen atmosphere.
2 mL of C6D6 were added.
Hydrogen (100 bar) was introduced in the vessel and
the reactor was heated at 60 ꢁC for 14 h (2a, 2b, 2d, 2e),
or at 40 ꢁC for 16 h (2c). Then it was cooled rapidly to
room temperature, the gas vented and the reaction prod-
uct filtered, under nitrogen atmosphere, to eliminate
residual Na2CO3 and CH3COONa; the light yellow
solution was transferred in a NMR tube.
(d), 2005 (w), 1964 (vs) cmꢀ1
.
1
NMR and IR data for 2d: H NMR (C6D6, 199.985
MHz): d 7.54 (m, 6H, Ho, P(p-FC6H4)3), 6.72 (m, 6H,
Hm, P(p-FC6H4)3), 1.62 (m, 6H, CH2P), 1.33 (m, 12H,
CH3CH2CH2), 0.88 (t, JHH = 6.8 Hz, 9H, CH3CH2),
ꢀ7.17 (pt, JHP = 23.8 Hz, 2H, HRu). 13C{1H} NMR
(C6D6, 50.286 MHz): d 202.1 (m, CO), 163.7 (d,
JCF = 256.3 Hz, Cp, P(p-FC6H4)3), 136.0 (m, Co, P(p-
FC6H4)3), 134.8 (d, JCP = 10.3 Hz, Ci, P(p-FC6H4)3),
115.7 (m, Cm, P(p-FC6H4)3), 32.1 (d, JCP = 27.3,
CH2P), 26.5 (s, CH2CH2P), 24.7 (d, JCP = 13.6 Hz,
CH3CH2), 14.0 (s, CH3CH2). 31P{1H} NMR (C6D6,
121.421 MHz): d 53.3 (A part of an AB spin system,
JPP = 212.4 Hz, 1P, P(p-FC6H4)3), 35.2 (B part of an
AB spin system, JPP = 212.4 Hz, 1P, PnBu3). IR
1
IR, H, 31P, 13C NMR spectra were then recorded.
The data obtained indicated quantitative transforma-
tion of the starting complexes 1a–1e in the correspond-
ing dihydrides 2a–2e. Spectroscopic analyses show the
contemporary formation of small amounts of Ru-
(CO)2(CH3COO)2(PnBu3)2
XC6H4)3]2.
and
RuH2(CO)2[P(p-
1
NMR and IR data for 2a: H NMR (C6D6, 199.985
MHz): d 7.85 (m, 6H, Ho, P(p-CH3OC6H4)3), 6.72 (m,
6H, Hm, P(p-CH3OC6H4)3), 3.18 (s, 9H, CH3O), 1.68
(m, 6H, CH2P), 1.36 (m, 12H, CH3CH2CH2), 0.89 (t,
JHH = 6.8 Hz, 9H, CH3CH2), ꢀ6.87 (pt, 2H, HRu,
JHP = 23.8 Hz). 13C{1H} NMR (C6D6, 50.286 MHz): d
203.1 (m, CO), 160.9 (s, Cp, P(p-CH3OC6H4)3), 135.6
(d, JCP = 13.7 Hz, Co, P(p-CH3OC6H4)3), 130.8 (m, Ci,
P(p-CH3OC6H4)3), 113.7 (d, JCP = 10.3 Hz, Cm, P(p-
CH3OC6H4)3), 54.6 (s, P(p-CH3OC6H4)3), 32.3 (d,
JCP = 27.3 Hz, CH2P), 26.5 (s, CH2CH2P), 24.6 (d,
JCP = 13.7 Hz, CH3CH2), 14.0 (s, CH3CH2). 31P{1H}
NMR (C6D6, 121.421 MHz): d 49.8 (A part of an AB
spin system, JPP = 215.0 Hz, 1P, P(p-CH3OC6H4)3),
35.2 (B part of an AB spin system, JPP = 215.0 Hz, 1P,
(C6D6) 2036 (d), 2007 (w), 1966 (vs) cmꢀ1
.
1
NMR and IR data for 2e: H NMR (C6D6, 199.985
MHz): d 7.47 (m, 6H, Ho, P(p-ClC6H4)3), 7.03 (m, 6H,
Hm, P(p-ClC6H4)3), 1.58 (m, 6H, CH2P), 1.36 (m, 12H,
CH3CH2CH2), 0.87 (m, 9H, CH3CH2), ꢀ7.27 (pt,
JHP = 23.8 Hz, 2H, HRu). 13C{1H} NMR (C6D6,
50.286 MHz): d 202.5 (t, JCP = 9.3 Hz, CO), 136.7 (s,
Cp, P(p-ClC6H4)3), 135.6 (d, JCP = 13.7, Co, P(p-
ClC6H4)3), 133.9 (d, JCP = 13.7 Hz, Ci, P(p-ClC6H4)3),
128.9 (d, JCP = 20.5 Hz, Cm, P(p-ClC6H4)3), 32.6 (d,
JCP = 27.3 Hz, CH2P), 26.9 (m, CH2CH2P), 25.0 (d,
JCP = 13.7 Hz, CH3CH2), 14.4 (s, CH3CH2). 31P{1H}
NMR (C6D6, 121.421 MHz): d 54.6 (A part of an AB
spin system, JPP = 214.7 Hz, 1P, P(p-ClC6H4)3), 35.3
(B part of an AB spin system, JPP = 214.7 Hz, 1P,
PnBu3). IR (C6D6) 2036 (d), 2002 (w), 1961 (vs) cmꢀ1
.
1
NMR and IR data for 2b: H NMR (C6D6, 199.985
MHz): d 7.87 (m, 6H, Ho, P(p-CH3C6H4)3), 6.94 (m,
6H, Hm, P(p-CH3C6H4)3), 1.97 (s, 9H, P(p-CH3C6H4)3),
1.66 (m, 6H, CH2P), 1.36 (m, 12H, CH3CH2CH2), 0.89
(t, JHH = 7.2 Hz, 9H, CH3CH2), ꢀ6.93 (pt, JHP = 23.8
Hz, 2H, HRu). 13C{1H} NMR (C6D6, 50.286 MHz): d
202.5 (m, CO) [the Ci signal is probably overlapped with
the Cp one], 138.8 (s, Cp, P(p-CH3C6H4)3), 133.6
(d, JCP = 10.3 Hz, Co, P(p-CH3C6H4)3), 128.4 (d,
PnBu3). IR (C6D6) 2036 (d), 2008 (w), 1967 (vs) cmꢀ1
.
4.3.9. RuH(CO)2(CH3COO)(PnBu3)[P(p-XC6H4)3]
[X = CH3O, H] (3a, 3c)
JCP = 10.3 Hz, Cm, P(p-CH3C6H4)3), 31.8 (d, JCP
=
A
solution of RuH2(CO)2(PnBu3)[P(p-XC6H4)3]
27.3 Hz, CH2P), 26.0 (m, CH2CH2P), 24.2 (d,
JCP = 13.7 Hz, CH3CH2), 20.6 (s, P(p-CH3C6H4)3),
13.5 (s, CH3CH2). 31P{1H} NMR (C6D6, 121.421
(X = CH3O, H) (2a, 2c) (33 mmol) in C6D6 (2 mL)
has been transferred in the NMR sample tube and an
equimolecular amount of acetic acid was added, leaving

F. Micoli et al. / Journal of Organometallic Chemistry 690 (2005) 4867–4877
4877
(q) G.G. Mather, A. Pidcock, G.J.N. Rapsey, J. Chem. Soc.,
Dalton Trans. (1973) 2095;
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10 (1973) 335;
11 mL of free volume. The formation of the specie
RuH(CO)2(CH3COO)(PnBu3)[P(p-XC6H4)3] (3a, 3c) at
1
room temperature was checked by H and 31P NMR
spectroscopy. After 48 h the conversion reached 32%
for 3a and 45% for 3c and the new complexes were spec-
troscopically characterized.
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1
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NMR and IR data for 3a: H NMR (C6D6, 399.92
MHz): d ꢀ4.45 (pt, JHP = 20.1 Hz, 1H, HRu) (only hy-
dride region was reported). 31P{1H} NMR (C6D6,
121.421 MHz): d 37.5 (A part of an AB spin system,
JPP = 260.4 Hz, 1P, P(p-CH3OC6H4)3), 29.3 (B part of
an AB spin system, JPP = 260.4 Hz, 1P, PnBu3).
1
NMR and IR data for 3c: H NMR (C6D6, 399.92
MHz): d ꢀ4.20 (pt, JHP = 20.0 Hz, 1H, HRu) (only hy-
dride region was reported). 31P{1H} NMR (C6D6,
121.421 MHz): d 43.4 (A part of an AB spin system,
JPP = 254.6 Hz, 1P, PPh3), 30.8 (B part of an AB spin
system, JPP = 254.6 Hz, 1P, PnBu3).
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Acknowledgements
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The authors thank the University of Florence and the
Ministero della Istruzione, UniversitaÕ
e Ricerca
(M.I.U.R.), Programmi di Ricerca Scientifica di Notev-
ole Interesse Nazionale, Cofinanziamento 2003–04, for
financial support. We also thank the Ente Cassa di
Risparmio di Firenze (Italy) for granting a 400 MHz
NMR spectrometer and Maurizio Passaponti, Depart-
ment of Organic Chemistry, University of Florence,
for elemental analysis.
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