Complexation on rhodium of bidentate and potentially hemilabile phosphorous ligands

Article abstract of DOI:10.1016/S0022-328X(98)00662-7

Various bifunctional potentially hemilabile ligands bearing phosphorous groups have been prepared and their coordination to rhodium has been studied.Their effect on the hydroformylation of styrene has been assessed.Keywords: Hemilabile ligand; Rhodium; Phosphonate; Hydroformylation

Full text of DOI:10.1016/S0022-328X(98)00662-7

Journal of Organometallic Chemistry 567 (1998) 13–20
Complexation on rhodium of bidentate and potentially hemilabile
phosphorous ligands
Ire`ne Le Gall, Pascale Laurent, Eric Soulier, Jean-Yves Salau¨n, Herve´ des Abbayes *
Laboratoire de Chimie, Electrochimie Mole´culaires et Chimie Analytique, UMR CNRS 6521, Uni6ersite´ de Bretagne Occidentale,
UFR Sciences et Techniques, 6 a6enue Le Gorgeu, BP 809, 29285 Brest Cedex, France
Received 30 September 1997
Abstract
Various bifunctional potentially hemilabile ligands bearing phosphorous groups have been prepared and their coordination to
rhodium has been studied. Their effect on the hydroformylation of styrene has been assessed. © 1998 Elsevier Science S.A. All
rights reserved.
Keywords: Hemilabile ligand; Rhodium; Phosphonate; Hydroformylation
1. Introduction
[RhCl(CO)2]2 1 or the di-v-chloro-di-(1,5-cyclooctadi-
ene)dirhodium(I) [RhCl(COD)]2 2.
Since the introduction of the concept of hemilability
in coordination chemistry at the end of the 1970s [1],
there has been considerable interest in the use of so-
called hemilabile ligands in recent years [2–5]. They
have two different coordination centers: one functional
group strongly bound to a transition metal and another
coordinatively labile. The latter can dissociate from the
metal allowing the formation of a free coordination
site, which may be important in homogeneous catalysis
for incorporation of substrates; whereas the chelate
effect of these ligands confers stability on the catalyst
precursor in the absence of the substrate [6,7]
Their effect on the hydroformylation of styrene with
a rhodium catalyst has been assessed.
2. Results and discussion
2.1. Complexation of phosphine-phosphonate and
ether-phosphine ligands
Treatment of [RhCl(CO)2]2 1 with two equivalents of
phosphine-phosphonate in CH2Cl2 at r.t. leads, by
cleavage of the chloro-bridges, to mononuclear deriva-
We have used a series of mixed bidentate potentially
hemilabile ligands (Scheme 1)—ether-phosphine [3–9]
or amine-phosphine [10], and ligands bearing the less
studied phosphonate groups like phosphine-phospho-
nate [11], amine-phosphonate and allyl-phosphonate—
to study their complexation on rhodium dimeric
compounds: the tetracarbonyl-di-v-chlorodirhodium(I)
* Corresponding author. Tel.: +33 298016127; fax: +33
298016594; e-mail: abbayes@univ-brest.fr
Scheme 1.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S 0 0 2 2 - 3 2 8 X ( 9 8 ) 0 0 6 6 2 - 7

14
I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
tives whose spectroscopic data show the coordination of
the phosphine group [12,13].
These compounds 3 easily undergo a decarbonylation
process to give rise to the chelate complexes 4 [14]. This
type of reaction is generally observed in the reaction of
dimer 1 with most usual bidentate ligands [16].
Indeed, at 0°C, the 31P-NMR spectrum of 8 in CDCl3
presents three signals at 42.9, 27.1 and 19.0 ppm,
respectively ascribed to the phosphine, the free phos-
phonate and the coordinated phosphonate groups. An
increase in the temperature produces the coalescence of
the two later, and only one signal at 22.4 ppm is
observed for the phosphonate groups at 60°C, indicat-
ing the equivalence of these two functions. This rapid
exchange between the phosphonates highlights their
great lability.
The addition of the phosphonate-phosphine on dimer
2 has been recently described by Bischoff et al. [11]. The
monodentate and bidentate complexation of the ligand
have been observed and the hemilability of the ligand
has been brought to the fore by reaction with carbon
monoxide.
This structure has been confirmed by the single crystal
structure determination of complex 4b (reaction 2, R=
iPr) (Fig. 1). It shows that the phosphine group is trans
to the chlorine. The coordination of the phosphoryl
˚
(PꢀO) is indicated by a longer bond length (1.490(7) A)
than the PꢀO bond length of an uncoordinated phospho-
nate group [17]. Such a coordination of the phosphoryl
group is shown on complex cis-RhCl(CO)Ph2PCH2
P(O)Ph2, obtained by reaction of the phosphine-phos-
phine oxide ligand Ph2PꢁCH2ꢁP(O)Ph2 on dimer 1 [15].
Analogous results are obtained by reaction of dimer
1 with the ether-phosphine ligands. Indeed, the spectro-
scopic data of the obtained compounds [18] are in
accordance with the formation of complexes 5 and 6.
The hemilabile behaviour of the ligands is illustrated
by the reaction of the chelate complexes with carbon mo-
noxide: bubbling CO at r.t. through a dichloromethane
solution of 4 or 6 quantitatively affords the complexes
3 or 5 and purging with N2 regenerates the chelates.
2.2. Complexation of amine-phosphine ligands
Reaction of 1 with two equivalents of Ph2PꢁCH2ꢁ
CH2ꢁNMe2 under the precedently described conditions
instantaneously affords the cyclic complex 9 [20].
The lability of the phosphonate function is also
well-established by the 31P-NMR spectroscopic study of
complex 8, similarly obtained by reaction of dimer 1 with
two equivalents of the phosphine-diphosphonate ligand
Ph2PꢁCH2ꢁCH(P(O)(OEt)2)2 [19].
A careful monitoring of the reaction at low temperature
has not allowed the spectroscopic observation of a
transient compound bearing a monodentate ligand.

I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
15
2.3. Complexation of amine-phosphonate ligands
Concerning the amine-phosphonate ligands, the na-
ture of the amino group is of importance. Indeed, when
a tertiary amine-phosphonate is used, complexes ob-
tained from reaction with dimer 1 or 2 are found very
unstable and cannot be characterised. Similar reaction
on 1 has been studied by Abu-Gnim and Amer with the
tertiary amino-phosphine oxide ligand Me2Nꢁ
CH2ꢁP(O)Ph2. It allows the characterisation of a com-
pound which seems to be the chelate complex cis-
¸¹¹¹¹¹¹¹¹¹¹¹¹¹º
RhCl(CO)Me2NCH2P(O)Ph2 [23].
On the other hand, when the amino-phosphonate
ligands bears a secondary or a primary amine function,
complexes in which the ligand is monodentate and
bound by the amino group [24] are isolated from
reaction with dimer 1 or 2.
˚
Fig. 1. Molecular structure of 4b. Selected bond lengths (A): RhꢁCl,
2.364(2); RhꢁP(1), 2.206(2); RhꢁO(2), 2.123(7); RhꢁC(1), 1.79(1);
P(2)ꢁO(2), 1.490(7). Selected bond angles (°): ClꢁRhꢁO(2), 88.2(2);
ClꢁRhꢁP(1), 174.52(8); ClꢁRhꢁC(1), 93.9(3); P(1)ꢁRhꢁO(2), 88.1(2);
RhꢁO(2)ꢁP(2), 117.3(3).
On the other hand, reaction of this amine-phosphine
with dimer 2 allows the isolation of monodentate com-
plex 10, with the phosphine group bound to the
rhodium centre [21].
The single crystal structure for complex 12 confirms
this structure (Fig. 2). The PꢀO bond length (1.438(6)
˚
A) is shorter than the one observed for the coordinated
phosphonato group of 4b. However, this value is identi-
cal to the one usually observed for free phosphonates
[18].
Addition of AgBF4 on 10 leads to the chelate cation
11 [21]. A similar cyclic complex has been directly
obtained by Anderson and Kumar by reaction of dimer
2 with Ph2PCH2NMe2 in the presence of NaBPh4 in
acetonitrile [22].
Since the amino group of complexes 9 and 11 re-
mains bound to the metal centre in the presence of
carbon monoxide pressure, this amine-phosphine ligand
cannot be considered as hemilabile under these experi-
mental conditions.
These complexes, 12–14, are very stable, and what-
ever the conditions (heating under vacuum or reaction
with the CO trap Me3NO for 12 and 13, reaction with
AgBF4 for 14), do not evolve toward the formation of
the cyclic form with a bidentate ligand. Therefore, the
amine-phosphonate compounds cannot be regarded as
hemilabile bidentate ligands under the experimental
conditions of this work.

16
I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
2.4. Complexation of allyl-phosphonate ligands
and two bridging mixed bidentate ligands in the cis
position. Indeed, if Ph2PꢁCH2ꢁP(S)Ph2 (dppms) is
A more original result is observed in the reaction of
the allyl phosphonate CH2ꢀCHꢁCH2ꢁP(O)(OEt)2 with
dimer 1 [24].
known to give the cyclic monomer complex
¸¹¹¹¹¹¹¹¹¹¹¹¹¹¹º
[Rh(Cl)(CO)(Ph2PꢁCH2ꢁP(S)Ph2) by reaction with 1
Indeed, if the first step is similar: cut of chloro-bridges
and allyl coordination, the decarbonylation process
does not lead to the chelate mononuclear complex, but
to the dimer 16, in which the two rhodium centres are
bridged by two allyl-phosphonate ligands in the cis
position. The single crystal structure for this original
complex 16 has been realised (Fig. 3).
[25], in particular conditions it leads to the dimeric
complex [Rh(Cl)(CO)(v-dppms)2Rh(Cl)(CO)], with the
phosphine trans to the thiophosphoryl [26]. Similarly,
the reaction of the rhodium carbonyl chloride dimer 1
To our knowledge, 16 is the first bimetallic rho-
dium complex bearing chlorine and carbonyl ligands
˚
Fig. 3. Molecular structure of 16. Selected bond lengths (A):
Rh(1)ꢁCl(1), 2.327(3); Rh(1)ꢁO(2), 2.092(7); Rh(1)ꢁC(1), 1.76(1);
Rh(1)ꢁC(2), 2.12(1); Rh(1)ꢁC(3), 2.13(1); O(2)ꢁP(1), 1.482(7). Se-
lected bond angles (°): Cl(1)ꢁRh(1)ꢁO(2), 90.6(2); Cl(1)ꢁRh(1)ꢁC(1),
92.0(4); Cl(1)ꢁRh(1)ꢁC(2), 165.9(3); Cl(1)ꢁRh(1)ꢁC(3), 155.6(3);
˚
Fig. 2. Molecular structure of 12. Selected bond lengths (A): RhꢁCl,
2.335(2); RhꢁN, 2.118(2); RhꢁC(1), 1.802(9); RhꢁC(2), 1.849(8);
PꢁO(3), 1.438(6). Selected bond angles (°): ClꢁRhꢁN, 89.1(1);
ClꢁRhꢁC(1), 88.4(2); ClꢁRhꢁC(2), 178.1(3); NꢁRhꢁC(1), 177.1(3);
NꢁRhꢁC(2), 92.8(3); C(1)ꢁRhꢁC(2), 89.7(4).
O(2)ꢁRh(1)ꢁC(1),
175.1(4);
C(2)ꢁRh(1)ꢁC(3),
38.1(4);
Rh(1)ꢁO(2)ꢁP(1), 145.4(4).

I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
17
with Ph2PꢁCH2ꢁSMe has been shown to give the binu-
clear face-to-face complex with the phosphine trans to
the thioether group [27].
The distance between the allyl and the phosphonate
groups does not seem to be responsible for the forma-
and excellent selectivity at 25°C for some of our lig-
ands, in particular the amino-phosphine and the amino-
phosphonate compounds, whereas PPh3 remains
inactive under the same conditions.
It is noteworthy that the best results are obtained
with the tertiary amine-phosphonate ligand, which is
the only one to give no stable complex with dimer 1 or
2. This can show the importance of the lability of the
ligands in catalytic reactions.
tion of 16 since the cyclic monomeric complex
¸¹¹¹¹¹¹¹¹¹¹¹º
[Rh(Cl)(L)(CH2ꢀCHꢁNHPh)], bearing a shorter biden-
tate ligand, has been described [28].
The hemilabile behaviour of the allyl-phosphonate
ligand in complex 16 is illustrated by its reaction with
carbon monoxide (below). Bubbling CO at r.t. through
a dichloromethane solution of 16 affords the mononu-
clear complex 15 bearing the monodentate allyl-phos-
phonate ligand for which reversible coordination of the
oxygen is observed; whereas the metal–olefin bond
remains intact. Purging with nitrogen regenerates com-
plex 16 indicating that the reaction is reversible.
3. Conclusion
We have studied the coordination to rhodium of
various bifunctional potentially hemilabile ligands.
Thus, some compounds like amino-phosphonates, ex-
To our knowledge, this reaction is the first example
that shows the hemilability of a mixed bidentate ligand
with an allyl moiety. Consequently, this new type of
complex represents an interesting potential model for
the study of catalytic functionalisation of olefins involv-
ing labile ligands.
clusively give monodentate complexes. Conversely, the
amino-phosphine ligands lead to bidentate complexes.
In these model studies, we have seen no evidence for
hemilabile behaviour of the ligands.
On the other hand, compounds like ether-phosphine,
phosphine-phosphonate and allyl-phosphonate are per-
fectly hemilabile and the monodentate and bidentate
forms of the ligands can be observed by complexation
on rhodium. Moreover, this study has allowed the
synthesis of original complexes that represent interest-
ing models for the study of catalytic reactions.
Examination of the catalytic activity of the mixed
ligands on the hydroformylation of styrene has shown
promising results.
2.5. E6aluation of the catalytic acti6ity of the
bifunctional ligands
We have studied the activity of the above described
mixed-donor ligands on the catalytic hydroformylation
of styrene. The transformation of styrene under carbon
monoxide and dihydrogen pressure with dimer 2 leads
to two isomeric aldehydes.
Under the conditions usually used for the study of
this reaction (CH2Cl2, 80°C, 1 h, 40 bar), Table 1 shows
that if the conversion of styrene into aldehydes is high,
the selectivity (B/L) is lower than the one obtained with
the reference PPh3.
4. Experimental
All manipulations were performed under an atmo-
sphere of nitrogen with standard Schlenk techniques,
and all solvents were distilled under an inert atmo-
sphere from an appropriate drying agent [29].
More interestingly, Table 2 shows good conversion

18
I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
Table 2
IR spectra were recorded in dichloromethane on a
Hydroformylation of styrene at 25°Ca
Perkin-Elmer 1430 spectrophotometer. The 31P-NMR
(121.49MHz) spectra were obtained in CDCl3 on a
Bruker AC300 spectrometer using 87% HPO4 as an
external standard.
Ligand
Conversion (%)
Selectivity (%)
Without ligand
0
0
—
—
The hydroformylation experiments were conducted
in a stainless steel autoclave equipped with a mechani-
cal stirrer. The styrene in dichloromethane was progres-
sively introduce with a HPLC Gilson 307 pump.
GC analysis were made on a HP5890 equipped with
a 25×0.25 mm SE30 capillary column. Quantitative
measurements used toluene as internal standard.
PPh3
1
8
100/0
100/0
4.1. General procedure for the preparation of
complexes 4, 6, 8, 9, 12, 13 and 16
To a solution of [RhCl(CO)2]2 1 (0.25 mmol, 97 mg)
in 10 ml of dichloromethane, two equivalents of ligand
30
99/1
Table 1
Hydroformylation of styrene at 80°Ca
Ligand
PPh3
Conversion (%)
Selectivity (%)
60
67
99/1
99/1
77
75
92/8
64/36
55
82
65/35
66/34
Pressure CO/H2 (1:1)=40 atm, 15 h; [RhCl(COD)2]/ligand/styrene=
1:4:167, for a monofunctional ligand; [RhCl(COD)2]/ligand/styrene=
1:2:167, for a bifunctional ligand.
(0.50 mmol) are added at r.t. The reaction is monitored
by IR spectroscopy. After 30 min stirring, the two
bands w(CO) of 1 (2080, 2030 cm−1) have disappeared
and the solvent is removed under vacuum. The residue
is washed with hexane and recrystallised in a mixture of
hexane:dichloromethane 2:1.
80
84
87/13
63/37
4.2. General procedure for the preparation of
complexes 10, 14 and 15
Two equivalents of ligands (0.40 mmol) are added in
a dichloromethane solution (10 ml) of [RhCl(COD)]2 2
(100 mg, 0.20 mmol) at r.t. After 1 h stirring, the
solvent is removed and the residue washed with hexane.
The complexes are recrystallised in a mixture of hex-
ane:dichloromethane 2:1.
a Pressure CO/H2 (1:1)=40 atm,
styrene=1:4:167, for a monofunctional ligand; [RhCl(COD)2]/ligand/
styrene=1: 2:167, for a bifunctional ligand.
1
h; [RhCl(COD)2]/ligand/

I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
19
Table 3
Crystal data and structure refinement for 4b
Table 4
Crystal data and structure refinement for 12
Formula
RhClP2C20H26O4
Formula
RhClPC10H18NO5
Molecular weight
Crystal system
Space group
530.73
Triclinic
P1
Molecular weight
Crystal system
Space group
401.59
Triclinic
P1
˚
˚
a (A)
8.988(6)
11.586(7)
12.621(6)
66.16(5)
73.14(4)
83.21(5)
1150(1)
2
1.532
270
10.057
294
a (A)
8.888(2)
10.547(3)
10.804(4)
61.89(3)
68.13(3)
74.04(3)
822.9(5)
2
1.621
404
12.923
294
˚
˚
b (A)
b (A)
˚
˚
c (A)
c (A)
h (°)
i (°)
k (°)
h (°)
i (°)
k (°)
3
3
˚
˚
V (A )
V (A )
Z
Z
zcalc (g cm−3
F(000)
)
zcalc (g cm−3
F(000)
)
v(Mo–Kh)
T (K)
v(Mo–Kh) (cm−1
T (K)
)
Crystal size (mm)
Radiation
Max 2q (°)
0.25×0.28×0.30
Mo–Kh
50
Crystal size (mm)
Radiation
Max 2q (°)
0.20×0.30×0.30
Mo–Kh
50
Range of hkl
0–10; −13–13;
−14–14
4324
Range of hkl
0–10; −12–12;
−12–12
4235
No. of reflections measured
No. of reflections measured
no. of reflections observed (I\|(I))
Rint (from merging equiv. reflections)
2495 (4|)
0.024
No. of reflections observed (I\|(I))
Rint (from merging equiv. reflections)
1873 (3|)
0.026
R (isotropic)
0.088
R (isotropic)
0.085
R (anisotropic)
0.072
R (anisotropic)
0.057
N(obs.)/N(var.)
R
2495/331
0.061
N(obs.)/N(var.)
R
1873/197
0.045
Rw
0.053
Rw
0.045
w=1/|(Fo)2=[|2(I)+(0.004F2o)2]−1/2
w=1/|(Fo)2=[|2(I)+(0.004F2o)2]−1/2
Sw
2.156
1.41
2.11
Sw
0.785
0.66
0.02
−3
−3
˚
˚
Max residual (e A
D/|
)
Max residual (e A
D/|
)
4.3. General procedure for the preparation of complex
11
determined by least-squares fitting of a set of 25 high-q
reflections. After Lorentz and polarisation corrections,
the structures were solved with direct methods, scale
factor refinement and Fourier differences. The entire
structures were refined by full-matrix least-squares tech-
niques. Atomic scattering factors were taken from [30].
All calculations were performed on a digital Microvax
3100 computer with the MolEN package (Enraf-Non-
ius, 1990). The graphic illustrations have been realised
by the ORTEP program.
To a solution of [RhCl(COD)] 2 (80 mg, 0.16 mmol)
in 10 ml of dichloromethane two equivalents of ligand
(0. 32 mmol) are added. After 1 h stirring, the solution
is cooled to −5°C and AgBF4 (63 mg, 0.32 mmol) in
15 ml of THF is added. After 30 min stirring, the
mixture of solvents is removed. The residue is dissolved
in 10 ml of dichloromethane and the solution is filtered
to eliminate any AgCl formed. The complex is recrys-
tallised in a mixture of hexane:dichloromethane 2:1.
4.5. General procedure for the hydroformylation
reactions
4.4. Crystal structure analysis for complexes 4b, 12
and 16
In a typical run, 0.012 mmol of [RhCl(COD)]2 (5.9
mg) and 0.024 mmol of bifunctional ligand (or 0.048
mmol of monofunctional ligand) in 4 ml of di-
choromethane were placed in the autoclave under nitro-
gen atmosphere. The autoclave was pressurised with
CO (20 bar) and H2 (20 bar) and thermostated at the
required temperature. The solution of styrene (25.3
mmol, 2.9 ml) and toluene (25.4 mmol, 2.7 ml) in 25 ml
of dichloromethane was introduced with the high pres-
The microcrystals used for the X-ray studies have
been obtained by recrystallisation in a mixture of
dichloromethane:hexane 1:2.
The data were collected on a CAD-4 Enraf-Nonius
difractometer with graphite-monochromated Mo–Kh
radiation. Tables 3–5 give the experimental data for the
structures of 4b, 12 and 16. The unit cell parameters are

20
I. Le Gall et al. / Journal of Organometallic Chemistry 567 (1998) 13–20
Table 5
[11] S. Bischoff, A. Weigt, H. Miessner, B. Lu¨cke, J. Mol. Catal. A:
Chem. 107 (1996) 339.
[12] (a) 3a: w(CO): 2085, 2000 cm−1, w(PO): 1260 cm−1. (b) 3b:
w(CO): 2090, 2000 cm−1, w(PO): 1260 cm−1 31P-NMR, l: 24.1
Crystal data and structure refinement for 16
Formula
Rh2Cl2P2C16H30O8
689.08
Orthorhombic
Pbca
13.289(3)
17.511(9)
22.538(5)
5245(3)
8
1.745
2752
16.00
293
0.15×0.30×0.40
Mo–Kh
50
0–15; 0–20; 0–26
5124
2603 (4.0|)
0.095
0.072
;
Molecular weight
Crystal system
Space group
ppm (dd, 1JPRh=115.9 Hz, 3JPP(O)=47.8 Hz), 25.5 ppm (d,
3JPP(O)=47.8 Hz). The observation of two almost equally in-
tense bands in the (CO) region of the IR spectrum (:2090,
2000 cm−1, CH2Cl2) is in accord with cis Rh(Cl)(CO)2(L) com-
plexes [13]. A 31P-NMR shift downfield from the corresponding
˚
a (A)
˚
b (A)
1
˚
c (A)
resonance of uncoordinated phosphine and a JPRh of 115–125
3
˚
V (A )
Hz are observed.
Z
[13] (a) A.J. Pribula, R.S. Drago, J. Am. Chem. Soc. 98 (1976) 2784.
(b) R. Poilblanc, J. Gallay, J. Organomet. Chem. 21 (1971) C53.
[14] (a) 4a: w(CO): 1990 cm−1, w(PO): 1160 cm−1. (b) 4b: w(CO):
zcalc (g cm−3
F(000)
)
v(Mo–Kh) (cm−1
T (K)
)
1990 cm−1, w(PO): 1160 cm−1 31P-NMR, l: 33.3 ppm (d,
;
1JPRh=158 Hz), 45.7 ppm (s). The observation of one intense
band in the (CO) region of the IR spectrum (:1990 cm−1
,
Crystal size (mm)
Radiation
Max 2q (°)
Range of hkl
No. of reflections measured
No. of reflections observed (I\|(I))
R (isotropic)
R (anisotropic)
CH2Cl2) is in accord with cis-Rh(Cl)(CO)(L)(L%) complexes [15].
The value of the IR frequency w(PꢀO) represents an energy
decrease of ca. 100 cm−1 showing the coordination of the
phosphonate group [11]. A 31P-NMR shift downfield from the
corresponding resonance of free phosphonate is observed.
[15] R.W. Wegman, A.G. Abatjoglou, A.M. Harisson, J. Chem. Soc.
Chem. Commun. (1987) 1891.
Fourier difference
N(obs.)/N(var.)
R
0.36–0.15
2603/256
0.061
[16] P.R. Sharp, in: E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.),
Comprehensive Organometallic Chemistry, vol. 8, Pergamon,
Oxford, 1985, p. 115.
Rw
0.048
[17] S. Ganguly, J.T. Mague, D.M. Roundhill, Inorg. Chem. 31
(1992) 3500.
w=1/|(Fo)2=[|2(I)+(0.004F2o)2]−1/2
[18] (a) 5a: w(CO): 2095, 2000 cm−1
;
31P-NMR, l: 28.0 ppm (d,
31P-NMR, l:
31.3 ppm (d, 1JPRh=124.8Hz). (c) 6a: w(CO): 1990 cm−1
31P-NMR, l: 38.1 ppm (d, 1JPRh=173.7Hz). (d) 6b: w(CO): 1970
Sw
3.37
0.48
0.02
3
˚
1JPRh=125.0Hz). (b) 5b: w(CO): 2080, 2000 cm−1
;
Max residual (e A )
D/|
;
cm−1
;
31P-NMR, l: 43.0 ppm (d, 1JPRh=173.2Hz).
[19] 8: w(CO): 1990 cm−1
;
31P-NMR (273 K), l: 42.9 ppm (dd,
1JPRh=167.7Hz, 3JPP(O)=45.5Hz), 27.1 ppm (d, JP(O)P(O)
=
2
sure pump. After the reaction time quoted in Tables 1
and 2, the autoclave was cooled and flushed with
nitrogen. The reaction products were analysed by GC.
7.5Hz), 19.0 ppm (dd, 3JP(O)P=45.5Hz, 2JP(O)P(O)=45.5Hz).
[20] One band is observed in the (CO) region of the IR spectrum;
the 31P-NMR resonance of the phosphine (60.6 ppm) is shift
downfield from the corresponding resonance of free phosphine
(−20.0 ppm), 1JPRh=172.5Hz.
[21] (a) 10: 31P-NMR (CDCl3), l: 26.3 ppm (d, J=149.2Hz). (b) 11:
31P-NMR (CDCl3), l: 41.7 ppm (d, J=160.4Hz).
[22] G.K. Anderson, R. Kumar, Inorg. Chim. Acta 146 (1988) 89.
[23] C. Abu-Gnim, I. Amer, J. Chem. Soc. Chem. Commun. (1994)
115.
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