Oxidative addition of iodine, iodomethane and iodobenzene to the rhodium phosphino enolate complex [Rh{Ph2PCH - C(- O)Ph} (CO)(PPh3)] and carbon monoxide insertion into the resulting Rh-carbon bond of [Rh{Ph2PCH - C(- O)Ph} Me(I)(CO)(PPh3)]

Article abstract of DOI:10.1039/b000961j

The oxidative addition of homo- and heteronuclear molecules XI (X = I, Me, Ph) to the square planar rhodium phosphino enolate complex [Rh{Ph₂PCH - C(- O)Ph}(CO)(PPh₃)] 1 afforded the hexacoordinate Rh(III) complexes [Rh{Ph₂PCH -C(- O)Ph}X(I)(CO)(PPh₃)] (X = Me 2; X = Ph 3.; X = I 4). Complex 2 undergoes CO insertion into the Rh-Me bond to afford three isomers of the acetyl species [Rh{Ph₂PCH - C(- O)Ph}-{C(O)Me}(I)(CO)(PPh₃)] 5a- c. Two of these isomers lose acetyl iodide to regenerate 1 and these transformations were followed by NMR and IR spectroscopic methods. The reaction of 1 with acetyl chloride results in rapid formation of the acetyl complex [Rh{Ph₂PCH - C(- O)Ph}{C(O)Me}(Cl)(CO)(PPh₃)] 6. When left in solution, 6 isomerizes to give two additional isomeric acetyl species. All three isomers rapidly decompose to a Rh(I) species. The crystal structures of 1-3 have been determined by X-ray diffraction. The coordination geometry around the rhodium atom of 2 and 3 is distorted octahedral and the alkyl and halide ligands are in a mutually trans position.

Full text of DOI:10.1039/b000961j

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Oxidative addition of iodine, iodomethane and iodobenzene to the
rhodium phosphino enolate
complex[Rh{Ph PCHbC(bO)Ph}(CO)(PPh )] and carbon
w
z
2
3
monoxide insertion into the resulting Rh–carbon bond of
[Rh{Ph PCHbC(bO)Ph}Me(I)(CO)(PPh )]
w
z
2
3
Pierre Braunstein,*a Yves Chauvin,b Jean Fischer,c Helene Olivier,*b Carsten Strohmannd and
Dawn V. Torontob
a L aboratoire de Chimie de Coordination (CNRS UMR 7513), Universite L ouis Pasteur, 4 rue
Blaise Pascal, F-67070 Strasbourg cedex, France. E-mail: braunst=chimie.u-strasbg.fr
b Institut Francais du Petrole, BP 311, F-92506 Rueil-Malmaison, France
c L aboratoire de Cristallochimie et de Chimie Structurale (CNRS UMR 7513), Universite L ouis
Pasteur, 4 rue Blaise Pascal, F-67070 Strasbourg cedex, France
d Institut fur Anorganische Chemie, Universitat W urzburg, Am Hubland, D-97074 W urzburg,
Germany
Received (in Montpellier, France) 2nd February 2000, Accepted 27th March 2000
The oxidative addition of homo- and heteronuclear molecules XI (X \ I, Me, Ph) to the square planar rhodium
phosphino enolate complex [Rw hMPh PCHbC(bOz )PhN(CO)(PPh )] 1 a†orded the hexacoordinate Rh(III)
2
3
complexes [Rw hMPh PCHbC(bOz )PhNX(I)(CO)(PPh )] (X \ Me 2; X \ Ph 3; X \ I 4). Complex 2 undergoes CO
2
3
insertion into the RhÈMe bond to a†ord three isomers of the acetyl species [Rw hMPh PCHbC(bOz )PhN-
2
MC(O)MeN(I)(CO)(PPh )] 5aÈc. Two of these isomers lose acetyl iodide to regenerate 1 and these transformations
3
were followed by NMR and IR spectroscopic methods. The reaction of 1 with acetyl chloride results in rapid
formation of the acetyl complex [Rw hMPh PCHbC(bOz )PhNMC(O)MeN(Cl)(CO)(PPh )] 6. When left in solution, 6
2
3
isomerizes to give two additional isomeric acetyl species. All three isomers rapidly decompose to a Rh(I) species.
The crystal structures of 1–3 have been determined by X-ray di†raction. The coordination geometry around the
rhodium atom of 2 and 3 is distorted octahedral and the alkyl and halide ligands are in a mutually trans position.
thermore, ylide-substituted Ni phosphino enolates are highly
active catalysts for acetylene polymerization.7
Introduction
b-Ketophosphines such as Ph PCH C(O)Ph and keto (or
imino) phosphorus ylides such as Ph P2CHC(O)Ph represent
key ligands for the formation of phosphino enolate metal
Recent work in our laboratories has produced a variety of
phosphino enolate derivatives of Ni(II), Pd(II), Rh(I), Rh(III),
Ru(II) and Ir(I);8,9 some of them led to active homogeneous
catalysts. For example, Rh(I) complexes such as
[Rw hMPh PCHbC(bOz )PhN(CO)(PPh )] 1 have proved to be
2
2
3
complexes, a class of compounds of growing importance. Such
complexes may be obtained by deprotonation of the a-
methylene group of (coordinated) b-ketophosphines1 or by
oxidative addition of a PÈaryl bond of phosphorus ylides
across a transition metal complex, respectively, although only
Ni(0) complexes have been reported to perform this reaction.2
Phosphino enolate complexes have been described for many
transition metals, such as Re, Fe, Ru, Co, Rh, Ni, Pd and
Pt.1,3 They contain one or more planar chelate rings and are
generally very stable, although they display interesting reacti-
vity patterns. Provided that such complexes contain a metalÈ
carbon or metalÈhydrogen bond (or that such bonds could be
formed in an activation step), a catalytic species may be
obtained whose reactivity can be tuned by the steric and elec-
tronic properties of the substituents on the phosphino enolate
chelating ligand. Thus, nickel phosphino enolate complexes
are known to catalyze the oligomerization of ethylene into a-
oleÐns2,4 (Shell Higher OleÐn Process), the polymerization of
ethylene to high molecular weight polyethylene5 and the co-
oligomerization with polar monomers.6 Catalyst activity,
average chain length and degree of branching of the polymer
are strongly dependent on the phosphino enolate ligand. Fur-
2
3
active in catalytic hydrogenation of alkenes and in transfer
dehydrogenation of alkanes to alkenes.9 These results led us
to develop the chemistry of phosphino enolate Rh(I) complex-
es more extensively. Since oxidative addition reactions across
a transition metal centre represent key processes in many
catalytic reactions, such as carbonylation, hydrogenation or
oligomerization, our aim was to investigate the activity of
phosphino enolate complexes in such reactions. We Ðrst
studied the addition of iodine derivatives and then the activity
of the Rh(III) complexes thus obtained as regards insertion
reactions. The oxidative addition of various organic halides to
Rh(I) carbonyl phosphine complexes has been extensively
studied, particularly in the case of iodomethane, largely
because of its relevance to the catalytic carbonylation of meth-
anol.10h15 The e†ect of monoanionic bidendate ligands con-
taining donor atoms, such as O, N, or S, in Ðve- or
six-membered chelate rings on the formation of isomeric
forms of methyl, carbonyl or acetyl Rh(III) complexes has been
widely discussed.16h20 Chelating ligands of the phosphino
enolate type (P,O) are expected to induce more selectivity in
DOI: 10.1039/b000961j
New J. Chem., 2000, 24, 437È445
437
This journal is ( The Royal Society of Chemistry and the Centre National de la Recherche ScientiÐque 2000

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the coordination sphere of a metal than chelates with identical
donor atoms. Here, we focus on the reactivity of 19 towards
the oxidative addition of iodine derivatives and the possible
insertion of carbon monoxide into the newly formed metalÈ
carbon bond.
has also been observed with complexes of the form
[Rh(quinaldinate)(CO)(PR )] and in their oxidative addition
3
products.19
The 31PM1HN NMR spectra of complexes 2È4 show an ABX
(A, B \ P, X \ Rh) pattern with a strong 2J(P,P) coupling
diagnostic of a trans arrangement of the phosphorus atoms. In
the parent complex 1, a doublet for the enolate phosphorus
atom and a broad singlet for the triphenylphosphine ligand
were observed, indicating that, at room temperature, disso-
ciation of triphenylphosphine occurred.9 The presence of dis-
sociated triphenylphosphine always resulted in the formation
Results and discussion
Synthesis of complexes resulting from oxidative addition
Complex 1, whose crystal structure is described below, reacted
with an excess of MeI, PhI, or one equivalent of I to give
of a small quantity (\5%) of [MePPh ]`I~ during the syn-
2
3
Rh(III) complexes, as shown in eqn. (1). In all these products,
thesis of 2. Increasing the MeI : 1 molar ratio above 100 : 1
the ligands X and I are trans with respect to each other.
lowered the yield of 2 and increased the percentage of phos-
phonium salt produced.
The 1H NMR spectra of CD Cl solutions of 2 and 3
2
2
contain characteristic resonances, conÐrming the addition of
the methyl and phenyl group, respectively. For 2, the methyl
protons give rise to a triplet of doublets at d 0.78 as a result of
coupling to rhodium and the cis-phosphorus atoms. For all
three complexes, the signal corresponding to the enolate
proton appears as a doublet of doublets around d 5.30. These
NMR data are consistent with the presence of only one
isomer in solution. Spectroscopic details for complexes 2È4 are
given in the Experimental section.
(1)
The addition of a 10-fold excess of iodomethane to a
dichloromethane solution of 1 resulted in a colour change
from pale orange to yellow. Concentration of the solution and
addition of diethyl ether a†orded yellow crystals of
[Rw hMPh PCHbC(bOz )PhNMe(I)(CO)(PPh )] 2, whose struc-
Reaction of complex 2 with carbon monoxide
The reaction was monitored by 31PM1HN NMR spectroscopy.
When 0.2 MPa of carbon monoxide was applied to a CD Cl
2
2
solution of 2 at room temperature for 1 h, its characteristic
doublet of doublets resonance at d 14.5 and 46.1 with
1J(Rh,P) \ 92 and 89 Hz and 2J(P,P) \ 412 Hz was depleted
while new ABX patterns (A \ B \ P, X \ Rh) appeared,
2
3
ture has been determined crystallographically (vide infra). The
PhI analogue was synthesized by dissolving 1 in neat iodoben-
zene and heating under light reÑux. The formation of
[Rw hMPh PCHbC(bOz )PhNPh(I)(CO)(PPh )] 3 was accompa-
which
were
assigned
to
the
acetyl
complex
(3
2
3
nied by a darkening of the yellow solution. Concentration of
the solution led to the formation of yellow crystals of 3, which
were analyzed by X-ray di†raction to unambiguously deter-
mine the molecular stereochemistry (vide infra). IR monitoring
of the formation of 2 and 3 showed the reaction to be com-
plete when the l(CO) absorption at 1969 cm~1 was replaced
by a new band at 2046 or 2051 cm~1, respectively.
[Rw hMPh PCHbC(bOz )PhNMC(O)MeN(I)(CO)(PPh )]
5
2
3
stereoisomers 5aÈc) and 1 (Scheme 1). The magnitude of 2J(P,
P) (between 340 and 410 Hz) suggests that the phosphorus
atoms retain the trans arrangement present in 2. The acetyl,
carbonyl and iodo ligands therefore occupy positions cis to
both the phosphino enolate phosphorus atom and the tri-
phenylphosphine ligand. For such an arrangement, there are
six possible isomeric structures representing three pairs of
enantiomers and this is consistent with the spectroscopic data.
The IR spectrum exhibits a characteristic band at 1679 cm~1
for an acetyl ligand on Rh(III) that is very strong and slightly
asymmetric and may thus contain the absorptions corre-
sponding to each isomer.
Addition of one equivalent of I to a dichloromethane solu-
tion of 1 made the yellow solution turn red and IR spectros-
2
copy [l(CO), 2080 cm~1] showed the immediate formation of
a Rh(III) oxidative addition product. Addition of diethyl ether
produced a red powder that has been characterized as
[Rw hMPh PCHbC(bOz )PhN(I) (CO)(PPh )] 4, based on its
2
2
3
similar spectroscopic properties, compared to 2 and 3. The
ligand arrangement was conÐrmed by X-ray di†raction,
although the quality of the structure is too poor for pub-
lication.21
Based on similar carbonylation studies and the kinetic pref-
erence for the cis isomer over the trans isomer,22,23 the Ðrst
set of resonances seen in the 31PM1HN NMR spectrum is
assigned to one of the two structures with a mutual cis
arrangement of the acetyl and iodide ligands (5a d 8.5, d
41.0; Scheme 1), but the exact stereochemistry is uncertain.
The other sets were assigned to 5b (d 5.4, d 45.4) and 5c
The l(CbO) ] l(CbC) absorption of the phosphino
enolate ligand in the Rh(III) complexes 2È4 appears to be unaf-
fected by the change in electron density at the rhodium centre
and remains at 1525 cm~1, as found in the precursor complex
1. This has also been observed for the Rh(I) square planar
complexes [Rw hMPh PCHbC(bOz )PhN(CO)(L)] [L \ PMe ,
A
B
A
B
(d [ 1.8, d 40.2). Unfortunately, IR and 13C NMR studies
A
B
(vide infra) did not provide spectroscopic data allowing us to
distinguish between the stereoisomers. As the reaction con-
tinues, the resonances for 5a and 5b reach a maximum inten-
sity and then begin to diminish, those for 5c reach a maximum
and remain constant and the resonances due to 1 continue to
grow. Eventually, the two species remaining in solution are 5c
and 1, implying that reductive elimination of acetyl iodide has
occurred from 5a and/or 5b. It is well established that a con-
certed reductive elimination process can only occur between
cis ligands and that the trans conÐguration is thermodynami-
cally more stable; therefore, the remaining set of ABX reso-
nances in the NMR spectrum is assigned to the trans isomer
5c. The mechanism of the elimination reaction of acetyl iodide
has been well established in the catalytic carbonylation of
2
3
P(o-tolyl) , PPh (p-tolyl), P(p-FC H ) ],9 where the enolate
3
2
6 4 3
system delocalizes the electron density at the metal centre,
which results in a carbonyl stretching frequency almost inde-
pendent of the Bronsted basicity of the phosphine ligand (at
least in the range explored). When the oxidation state of the
metal is increased, the donor properties of the phosphino
enolate ligand do not compensate for the decrease in electron
density and this is reÑected in an increase of the stretching
frequency of the carbonyl group. The trend in l(CO) absorp-
tion, I [ Ph [ Me, agrees with the higher oxidative character
of iodine compared to phenyl iodide and methyl iodide and
reÑects the slightly p acidic nature of the phenyl group. This
438
New J. Chem., 2000, 24, 437È445

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Scheme 1
methanol by rhodium complexes.24 Scheme 1 depicts a similar
route, with the formation of complex 1 arising from the elimi-
nation of acetyl iodide from either of the cis intermediates 5a
or 5b.
ligand or through formal CO insertion into a cis-methylÈ
rhodium bond.27,28 Although our studies do not distinguish
between the two pathways, methyl migration has been shown
to predominate in a variety of carbonylation studies and is the
most common mechanism of the alkylÈacyl rearrangement
observed with organometallic complexes,29 including a variety
of [Rh(Y)Me(I)(CO)(PR ) ] and [RhMe(I)(CO)(PPh )(MBL)]
Isomerization of 5a could also account for the formation of
5b and 5c. Separate studies show that, while 5a isomerizes in
solution, the rate of this process is too slow to contribute sig-
niÐcantly to the formation of 5b and 5c. A CD Cl solution of
3 2
3
species (Y \ anionic ligand, MBL \ monoanionic bidentate
ligand).17,18 There are two possible routes available for
methyl migration, depending mainly on the ease of substitut-
ion of one of the anionic ligands by carbon monoxide and on
the solvent used.23 Acyl formation can occur either through
an ionic intermediate by reversible substitution of the anionic
ligand by CO, methyl migration to the cis-carbonyl and
recoordination of the anion (Scheme 2) or through direct
methyl migration to a cis-carbonyl group via an unsaturated
5-coordinated intermediate (presumably square pyramidal for
low spin rhodium d6 complexes), which rapidly isomerizes and
adds carbon monoxide (Scheme 3).23,30
2
2
2 was reacted with 0.2 MPa of carbon monoxide for a period
of 1È4 h after which time the reaction was quenched. The best
results were found after a reaction period of 4 h under CO,
although the kinetic isomer 5a was never formed exclusively
without 5b and 5c. Shorter reaction times did not allow a suf-
Ðcient build-up of 5a. After 4 h under CO, 5a accounts for
approximately 1/3 of the organometallic products visible. The
remaining constituents 2, 5c, 5b, and 1 are present in the ratio
8 : 2 : 1 : 2. Quenching the reaction by release of CO pressure
did not result in decarbonylation of the acyl species 5aÈc and
monitoring by both 1H NMR and 31PM1HN NMR spectro-
scopies showed that after three days there is very little change
in the resonance intensities for either the acetyl proton peaks
or the phosphorus peaks. While interconversion does occur
amongst the three isomers, the rate is too slow to contribute
signiÐcantly to the formation of these isomers during the car-
bonylation reaction. It is interesting that the more reactive
ruthenium complex [Ru(Me)(I)(CO) (PMe ) ] readily adds
For example, carbonylation of the ruthenium compounds
[RuMe(Y)(CO) (PMe ) ] (Y \ I, CN),23 in which the metalÈ
2
3 2
anion bond strengths are high, proceeds via a mechanism
similar to that in Scheme 3 rather than via anion substitution.
For the phosphino enolate compound 2, CO insertion is
likely to occur according to Scheme 3, assuming that the soft
iodide dissociates less readily from the rhodium atom,
as found in ruthenium complexes. In fact, this appears
to be consistent with the lower reactivity of 2 (ca. 4 h)
2
3 2
carbon monoxide at [30 ¡C to give cis-[RuMC(O)MeN(I)-
(CO) (PMe ) ], which rapidly converts to the trans isomer at
10 ¡C.25 Under similar conditions, 2 was found to be unre-
active towards carbon monoxide.
2
3 2
with AgOTf in CH Cl
to give the triÑate salt
2
2
[Rw hMPh PCHbC(bOz )PhNMe(CO)(PPh )](OTf) 731 when
2
3
Under reaction conditions similar to those used for 2,
complex 3 was found to be unreactive towards carbon mon-
oxide insertion. This appears to be due to a relatively strong
RhÈphenyl bond,25 which favours the phenyl over the benzoyl
complex. Kinetic and mechanistic studies of the acyl(benzoyl)-
alkyl(aryl) rearrangement of para-substituted benzoyl rhodium
complexes have shown that this rearrangement is irreversible
and proceeds in only one direction to yield the aryl
complex,26a whereas the reaction of the methyl complex pro-
ceeds only in the opposite direction and favours formation of
the acetylrhodium complex. Similarly, in the reactions
[RhR(CO)(PPh ) Cl ] H [RhMC(O)RN(PPh ) Cl ] the acyl
compared to the ruthenium complex [RuMe(I)(CO) (Pri-
2
DAB)] (Pri-DAB \ PriN2CHCH2NPri), which reacts with
AgOTf quantitatively after 15 min to form [RuMe(CO) (Pri-
2
Scheme 2
Scheme 3
3 2
2
3 2 2
form is favoured for R \ Me while the equilibrium is strongly
shifted to the left when R \ Ph.26bhd Note, however, that
faster migration of phenyl over methyl in a direct transform-
ation, RhR(CO) ] L ] RhMC(O)RNL, has been observed in
other rhodium complexes.26e,f
The stereochemical pathway to carbonylation can occur
either through methyl migration to a cis-carbon monoxide
New J. Chem., 2000, 24, 437È445
439

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20.1, which correspond to the increasing formation of isomers
5b and 5c, respectively, while eventually only the peak at d
20.1 remains. IdentiÐcation of the acyl carbon by 13CM1HN
NMR spectroscopy was unsuccessful due to insufficient inten-
sity of the unlabeled carbonyl group signal and the distribu-
tion of its intensity over three isomers with di†erent chemical
shifts. Details of the 13CM1HN NMR data for complex 2 are
reported in the Experimental section.
To complement the NMR studies, IR monitoring of the car-
bonylation of 2 was carried out in CD Cl at room tem-
2
2
perature. Upon addition of carbon monoxide, a new band
grows at 1679 cm~1, characteristic of an acyl complex. As the
reaction progresses, this band increases in intensity and the
carbonyl band of 2 at 2045 cm~1 broadens and shifts to
higher energy as 2 is consumed and replaced by the less elec-
tron rich acyl complexes 5aÈc. The l(CbO) ] l(CbC)
enolate absorption at 1525 cm~1 remains unchanged. After a
short induction period, an additional carbon monoxide
absorption appears at 1969 cm~1. This peak is characteristic
of the Rh(I) complex 1, which is formed upon reductive elimi-
nation of acetyl iodide. Throughout the course of the reaction,
only one observable acyl stretch at 1679 cm~1 and one car-
bonyl stretch at 2050 cm~1 appear in the IR spectrum, indi-
cating that the three isomers are indistinguishable by IR. Very
similar observations have been made for the two isomers of
[RhMC(O)MeN(I) MPh PCH P(S)Ph N(CO)].22 In agreement
Fig. 1 View
(Schakal)
of
the
structure
of
[Rw hMPh PCHbC(bOz )PhN(CO)(PPh )] 1.
2
3
2
2
2
2
with the NMR results, the IR spectrum at the end of the reac-
tion shows absorptions due mainly to the presence of 1, and
low intensity carbon monoxide and acyl absorptions due to
the remaining isomer 5c.
DAB)](OTf).32 Assuming that the pathway in Scheme 3 is
operative in the carbonylation of 2, methyl migration to give
a
5-coordinate square pyramidal intermediate followed
by isomerization and then coordination of the incoming
CO group would explain the formation of the three
isomers seen in the NMR spectrum. Such a behaviour Ðnds
precedent in a recent study by Baker et al.22 in which spectro-
Isolation of the acyl complexes for further characterization
was unsuccessful. We therefore attempted the direct synthesis
of [Rw hMPh PCHbC(bOz )PhNMC(O)MeNCl(CO)(PPh )] by
2
3
addition of acetyl chloride to 1 [eqn. (2)]. 31PM1HN NMR
scopic data consistent with
that adds CO to give
[RhMC(O)MeN(I) MPh PCH P(S)Ph N(CO)] were reported.
a
5-coordinate intermediate
monitoring of this reaction in CD Cl at room temperature
2
2
two stereoisomers of
indicated the formation of a rhodium acetyl species 6a with an
ABX pattern centered at d 3.7 and d 45.0.
2
2
2
2
A
B
Based on NMR data, these authors suggested a mutual trans
arrangement of the phosphorus and iodide ligands, thus pro-
viding a system in which all three enantiomeric pairs of
isomers possible would have the correct cis arrangement of
acetyl and iodide ligands to reductively eliminate acetyl
iodide. However, spectroscopic evidence for only two such
isomers was obtained.
Rw hMPh PCHbC(bOz )PhN(CO)(PPh ) ] MeC(O)Cl ]
2
3
1
Rw hMPh PCHbC(bOz )PhNMC(O)MeNCl(CO)(PPh ) (2)
2
3
6
A new 1H NMR resonance appeared as a singlet at d 2.19
whereas the enolate resonance gave rise to a doublet of doub-
lets at d 5.42. The IR spectrum showed a carbon monoxide
absorption at 2075 cm~1 and an absorption around 1675
cm~1 arising from the acetyl group. This acyl complex is not
stable, and within 10 min a light yellow powder begins to pre-
cipitate and the 31PM1HN NMR resonances due to 6a diminish
while a doublet at d 27 and two new complexes with an ABX
pattern appear. As the sample ages, other unidentiÐed
phosphine-containing products are formed. Filtration and
Unlike in other studies,15d,22 a 5-coordinate intermediate
and its isomerization products have not been observed by
spectroscopic methods. Thus, whether isomerization occurs
before or after CO insertion cannot be speciÐed. Several
studies in the past few years have emphasized the importance
of the former isomerization process in establishing the identity
of the mechanism of oxidative addition of iodomethane to
Rh(I) complexes.33 Isomerization from the primary oxidative
addition product is always an available pathway, resulting in
a di†erent ground state structure for the thermodynamic
product. While the solid state structure of 2 suggests an ionic
spectroscopic analysis of the yellow powder in CDCl showed
3
it to be responsible for the doublet at d 27 [1J(Rh,P) \ 127
S 2 two-step mechanism, the Ðnal trans arrangement of the
Hz]. The 1H NMR spectrum shows only aromatic protons
and the IR spectrum contains a carbon monoxide absorption
at 1975 cm~1, indicative of a Rh(I) complex. These data are
N
methyl and iodide ligands could have resulted from a con-
certed three-centre cis-addition followed by rapid isomer-
ization. That no intermediate could be detected during the
synthesis of 2 or during its carbonylation could be due to the
relatively slow oxidative addition reaction of 1 with MeI and
the slow rate of carbonylation of 2.
consistent with the presence of [RhCl(CO)(PPh ) ]. Analysis
3 2
of the mother liquor by IR and NMR revealed that a rhodium
acyl complex remained in solution. Similar to the reactions
studied by Wilkinson and coworkers on acyl halide addition
to Rh(I) complexes,26b,34 the acyl complex 6a is unstable with
respect to isomerization and decomposition, as shown in the
31P NMR spectrum by the growth of the peaks at d 24.4, d
In an attempt to follow the reaction by 13CM1HN NMR
spectroscopy, labeled 13CH I was used in the synthesis of 2.
3
The 13C analogue of 2 shows coupling to rhodium and two
A
B
phosphorus atoms, resulting in a doublet of triplets centered
at d 14. Mirroring both the 1H and 31PM1HN NMR data, the
13CM1HN NMR study shows the immediate formation of a
singlet at d 20.2 assigned to the acetyl ligand of isomer 5a. As
the reaction progresses, two new singlets grow at d 20.3 and
42.9 (6b) and d 18.5, d 45.1 (6c).
A
B
Solid 6a was isolated as a slightly impure Ñaky solid upon
immediate solvent removal at the end of the reaction. If placed
in dichloromethane, a similar sequence of decomposition and
isomerization occurs as was found during the synthesis. Like
440
New J. Chem., 2000, 24, 437È445

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Table
2
Selected bond lengths (A) and angles (deg) for
6a, 6b and 6c are unstable and readily decompose. Bearing in
mind literature reports, this instability is not surprising.34,35
For the formation of stable rhodium complexes of this type to
occur a delicate balance must exist between steric and elec-
tronic factors.36 Without a crystal structure of either 5 or 6 it
is difficult to evaluate the di†erent steric demands of the
ligands. On purely steric grounds, the larger iodide ion should
lead to greater steric crowding and result in an acyl complex
less stable than the chloride derivative. In fact, our results
show the opposite. Note, however, that steric e†ects may be
more complicated to analyze and conformational e†ects have
also been found to play a considerable role on the rate of
migratory CO insertion on rhodium.15d The greater stability
of 5aÈc over 6a–c suggests the participation of electronic
e†ects.
[Rw hMPh PCHbC(bOz )PhNMe(I)(CO)(PPh )] 2
2
3
RhÈP(1)
2.318(1)
2.418(1)
2.104(6)
2.7854(5)
1.824(5)
168.1(2)
101.0(2)
85.0(1)
83.2(2)
173.0(2)
90.7(2)
176.53(5)
82.5(1)
89.98(4)
RhÈO(1)
2.079(3)
1.123(6)
1.314(6)
1.368(7)
1.741(5)
86.8(2)
93.7(2)
89.51(3)
94.1(1)
93.0(2)
89.8(2)
176.0(2)
116.5(4)
123.3(4)
118.0(2)
RhÈP(2)
C(22)ÈO(2)
RhÈC(21)
C(1)ÈO(1)
RhÈI
C(1)ÈC(2)
RhÈC(22)
P(1)ÈC(2)
IÈRhÈC(21)
IÈRhÈC(22)
IÈRhÈO(1)
O(1)ÈRhÈC(21)
O(1)ÈRhÈC(22)
C(21)ÈRhÈC(22)
P(1)ÈRhÈP(2)
P(1)ÈRhÈO(1)
P(1)ÈRhÈI
P(1)ÈRhÈC(21)
P(1)ÈRhÈC(22)
P(2)ÈRhÈI
P(2)ÈRhÈO(1)
P(2)ÈRhÈC(21)
P(2)ÈRhÈC(22)
RhÈC(22)ÈO(2)
P(1)ÈC(2)ÈC(1)
C(2)ÈC(1)ÈO(1)
C(1)ÈO(1)ÈRh
Crystal structures
which there is a mutual trans relationship between the oxygen
atom of the bidentate enolate ligand and the carbon atom of
the CO ligand, the methyl and the iodide ligands, the tri-
phenylphosphine ligand and the phosphorus atom of the
enolate. The largest distortions from octahedral geometry are
seen in the following angles: O(1)ÈRhÈC(21) 83.2(2)¡, P(1)È
RhÈO(1) 82.5(1)¡ and IÈRhÈC(22) 101.0(2)¡. The non-bonded
distance between C(22)É É ÉC(21), 2.80 A, when compared to the
computed van der Waals distance, 3.6 A, indicates a strong
repulsive interaction between the methyl and carbon mon-
oxide ligand. Other neighbouring contacts are also repulsive
in nature: O(1)É É ÉI 3.33 A (vdW \ 3.55 A), O(1)É É ÉC(21) 2.78
A (vdW \ 3.40 A), IÉ É ÉC(22) 3.61 A (vdW \ 3.75 A), with the
latter interaction being the least repulsive due to the widening
of the IÈRhÈC(22) angle by 11¡. The rhodiumÈligand bond
distances observed in 2 are compared in Table 3 to those of
the related Rh(III) complexes trans-[RhMe(I)(ox)(CO)-
[Rw h{Ph PCHbC(bOz )Ph}(CO)(PPh )] 1. This complex
2
3
crystallizes with half a molecule of diethyl ether per formula
unit. Selected interatomic distances and angles are given in
Table 1. The molecular structure is shown in Fig. 1. The
square planar environment of the rhodium atom is similar to
that in [Rw hMPh PCH C(Oz )PhN(CO)(PPh )]PF , which, in
2
2
3
6
contrast to 1, contains a neutral ketophosphine ligand.9 As
expected, the RhÈO(1) bond is shorter in 1 [2.059(2) A] than
in [Rw hMPh PCH C(Oz )PhN(CO)(PPh )]PF
[2.084(4) A],
2
2
3
6
whereas in both complexes the carbonÈoxygen distances in
the CO ligand are similar [1.151(4) and 1.144(9) A,
respectively]. In both complexes, the RhÈP distance involving
the chelating ligand is shorter than that to the PPh ligand,
3
2.2793(9) vs. 2.3588(8) A in 1 and 2.281(3) vs. 2.343(3) A in
[Rw hMPh PCH C(Oz )PhN(CO)(PPh )]PF . The CÈH bond of
2
2
3
6
the enolato moiety is localized in the P(2)ÈC(3)ÈC(2) plane.
The P(2)ÈC(3) distance of 1.761(3) A is slightly longer
(PPh )],37 where ox is 8-hydroxyquinoline, and cis-[RhMe(I)-
3
(quin)(CO)MP(4-MeC H ) N],19 where quin is 2-quinaldinate
than
the
corresponding
PÈCH
distance
in
6
4 3
2
[Rw hMPh PCH C(Oz )PhN(CO)(PPh )]PF , consistent with the
2
2
3
6
sp2 character of the carbon atom in the former case. When
compared with the CH ÈC(Ph) and C2O distances in
2
[Rw hMPh PCH C(Oz )PhN(CO)(PPh )]PF , the C(2)ÈC(3) and
2
2
3
6
C(2)ÈO(1) distances in 1 are, respectively, shorter [1.363(4) vs.
1.505(9) A] and longer [1.320(4) vs. 1.252(6) A], which is con-
sistent with the electronic delocalization within the enolate
moiety and a strong double bond character for the C(2)ÈC(3)
bond.
[Rw h{Ph PCHbC(bOz )Ph}Me(I)(CO)(PPh )]
2.
This
2
3
complex crystallizes with one molecule in the asymmetric unit.
Selected interatomic distances and angles are given in Table 2.
The molecular structure is shown in Fig. 2. The coordination
polyhedron corresponds to a distorted octahedral geometry in
Table
1 Selected bond lengths (A) and angles (deg) for
[Rw hMPh PCHbC(bOz )PhN(CO)(PPh )] 1
2
3
RhÈC(1)
1.803(3)
2.059(2)
2.2793(9)
2.3588(8)
1.824(3)
1.826(3)
1.834(3)
174.16(11)
91.61(10)
82.54(6)
97.46(10)
88.38(6)
170.92(3)
106.8(2)
109.1(2)
P(2)ÈC(3)
1.761(3)
1.823(3)
1.825(3)
1.320(4)
1.151(4)
1.363(4)
1.491(4)
103.67(14)
100.61(11)
118.7(2)
175.1(3)
122.9(3)
114.4(2)
122.5(3)
114.7(2)
RhÈO(1)
P(2)ÈC(10)
Fig. 2 View
(ORTEP)
of
the
structure
of
RhÈP(2)
P(2)ÈC(16)
[Rw hMPh PCHbC(bOz )PhNMe(I)(CO)(PPh )] 2. Thermal ellipsoids
2
3
RhÈP(1)
O(1)ÈC(2)
are drawn at the 30% probability level.
P(1)ÈC(28)
O(2)ÈC(1)
P(1)ÈC(22)
C(2)ÈC(3)
Table 3 Comparison of bond lengths (A) between 2, cis-[RhMe(I)-
(quin)(CO)MP(4-MeC H )N] A and trans-[RhMe(I)(ox)(CO)(PPh )] B
P(1)ÈC(34)
C(2)ÈC(4)
6
4
3
C(1)ÈRhÈO(1)
C(1)ÈRhÈP(2)
O(1)ÈRhÈP(2)
C(1)ÈRhÈP(1)
O(1)ÈRhÈP(1)
P(2)ÈRhÈP(1)
C(3)ÈP(2)ÈC(10)
C(3)ÈP(2)ÈC(16)
C(10)ÈP(2)ÈC(16)
C(3)ÈP(2)ÈRh
C(2)ÈO(1)ÈRh
O(2)ÈC(1)ÈRh
O(1)ÈC(2)ÈC(3)
0(1)ÈC(2)ÈC(4)
C(3)ÈC(2)ÈC(4)
C(2)ÈC(3)ÈP(2)
2
A
B
RhÈI
RhÈCH
RhÈO
RhÈPPh
RhÈCO
2.7854(5)
2.104(6)
2.079(3)
2.418(1)
1.824(5)
2.701(2)
2.11(1)
2.039(9)
2.334(3)
1.81(1)
2.809(1)
2.104(8)
2.036(4)
2.317(2)
1.866(7)
3
3
New J. Chem., 2000, 24, 437È445
441

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anion. The overall structure of 2 is typical of alkyl halide
Rh(III) oxidative addition products. The RhÈC(21)H bond
3
distance in 2 [2.104(6) A] compares well with the values
observed in both the quin and ox complexes cited above. The
RhÈI bond [2.7854(5) A] is elongated with respect to the quin
complex by 0.084 A due to the strong trans inÑuence of the
methyl group but agrees well with the RhÈI distance found in
trans-[RhMe(I)(ox)(CO)(PPh )] [2.809(1) A].
3
The lengthening of the rhodiumÈtriphenylphosphine bond
in 2 distinguishes this complex from the quin and ox ana-
logues. The RhÈPPh bond distance in 2 [2.418(1) A] is sig-
3
niÐcantly longer than the RhÈPPh distances in cis-[RhMe(I)-
3
(quin)(CO)MP(4-MeC H ) N] [2.334(3) A] or trans-[RhMe(I)-
6
4 3
(ox)(CO)(PPh )] [2.317(2) A]. This trend complies with the
3
decreasing trans inÑuence P [ N [ I. The RhÈP(2) distance is
also 0.10 A longer than the bond between the rhodium and
the phosphorus atom of the enolate ligand; thus the trans
inÑuence of the two phosphorus atoms results in
a
lengthening of the RhÈP bond of the triphenylphosphine
ligand, while the RhÈP bond of the phosphino enolate ligand
is relatively una†ected.
The RhÈC(22)O and RhÈO(1) bond distances are similar to
those found in the cis and trans adducts. The remaining dis-
tances and angles found in the phosphino enolate ligand and
triphenylphosphine ligand are unexceptional. The CÈO
[1.314(6) A] and CÈC [1.368(7) A] bond distances within the
enolate ligand compare well with those in 1 and in other
Rh(III) enolate complexes in which electronic delocalization
leads to bond orders intermediate between single and double
bonds.
Fig. 3 View
(ORTEP)
of
the
structure
of
[Rw hMPh PCHbC(bOz )PhNPh(I)(CO)(PPh )] 3. Thermal ellipsoids are
2
3
drawn at the 30% probability level.
The metalÈligand bond distances in complex 3 are similar
to those in complex 2. The RhÈI bond distance [2.7752(3) A]
indicates that the phenyl, like the methyl group [RhÈI bond
2.7854(5) A], exerts a large trans inÑuence. Complexes having
a ligand with a small trans inÑuence opposite the RhÈI bond
usually have this bond falling within the 2.60È2.69 A range.
The RhÈC(21) distance in 3 [2.078(3) A] is shorter than the
[Rw h{Ph PCHbC(bOz )Ph}Ph(I)(CO)(PPh )]
3.
This
2
3
complex crystallizes with one molecule in the asymmetric unit.
Selected interatomic distances and angles are given in Table 4.
The molecular structure is shown in Fig. 3.
RhÈC(21)H distance in 2 [2.104(6) A] as a result of the
3
carbon sp2 hybridized orbital used in forming the metalÈ
ligand bond of the former. The shorter, stronger bond is also
responsible for the failure of 3 to insert carbon monoxide. The
rhodiumÈtriphenylphosphine bond in 3 [RhÈP(2) 2.4164(8) A]
is also elongated with respect to the rhodiumÈphosphino
enolate bond [RhÈP(1) 2.3285(8) A] and like 2, is considerably
longer than the metalÈphosphine distances found for the
related complexes tabulated in Table 3. The RhÈP bond in
both 2 and 3 is also approximately 0.03 A longer than the
corresponding bonds in [Rh(acac)(I) (PPh ) ] containing the
The coordination geometry is similar to the corresponding
iodomethane oxidative addition product. The C(21), C(27), I,
O(1) array is relatively planar although signiÐcant distortion
is observable in the compression of the P(2)ÈRhÈO(1) angle
[83.61(6)¡] and the accompanying widening of the P(2)ÈRhÈ
C(27) angle [99.8(1)¡). As a result of the bidentate nature of the
phosphino enolate ligand, the P(1)ÈRhÈO(1) bond angle is
also compressed [83.34(6)¡]. These distortions result in a 13¡
deviation from linearity for the P(1)ÈRhÈP(2) bond axis.
Overall a change from methyl to phenyl does not greatly
disturb the system. Non-bonding interactions between the
carbon monoxide and the alkyl or aryl ligands are observed in
2
3 2
trans-oriented PÈRhÈP unit.38 The bond distances within the
enolate ligand again indicate electronic delocalization.
2 and 3, respectively. The distances for the CH É É ÉCO inter-
Conclusions
3
action (2.80 A) and the PhÉ É ÉCO interaction (2.81 A) show
Previous studies have shown that the oxidative addition of a
covalent molecule to square planar carbonylphosphine
rhodium(I) complexes containing a monoanionic bidentate
ligand results in the formation of either cis/trans addition pro-
ducts or acyl complexes. Ligand variations have a marked
e†ect on the Lewis basicity of the metal centre and thus play a
major role in determining the reactivity, mechanism and Ðnal
ground state stereochemistry of the products formed. The oxi-
dative addition reactions to the enolate complex 1 were there-
fore of interest due to the di†erent r and p properties given by
the P,O ligand and the e†ects of this new metalÈligand inter-
action on the nucleophilicity of the metal complex. In addi-
tion, the presence of the carbon monoxide ligand o†ered the
interesting possibility of obtaining the 5-coordinate acetyl
complex [Rw hMPh PCHbC(bOz )PhNMC(O)RN(I)(PPh )] as the
that these groups Ðt snugly between neighbouring atoms.
Table
4 Selected bond lengths (A) and angles (deg) for
[Rw hMPh PCHbC(bOz )PhNPh(I)(CO)(PPh )] 3
2
3
RhÈP(1)
2.3285(8)
2.4164(8)
2.078(3)
2.7752(3)
1.859(4)
RhÈO(1)
2.052(2)
1.128(5)
1.308(4)
1.364(5)
1.749(4)
93.4(1)
89.75(9)
93.28(2)
83.61(6)
87.48(9)
99.8(1)
RhÈP(2)
C(27)ÈO(2)
RhÈC(21)
C(2)ÈO(1)
RhÈI
C(1)ÈC(2)
RhÈC(27)
P(1)ÈC(1)
IÈRhÈC(21)
IÈRhÈC(27)
IÈRhÈO(1)
O(1)ÈRhÈC(21)
O(1)ÈRhÈC(27)
C(21)ÈRhÈC(27)
P(1)ÈRhÈP(2)
P(1)ÈRhÈO(1)
P(1)ÈRhÈI
175.9(1)
P(1)ÈRhÈC(27)
P(1)ÈRhÈC(21)
P(2)ÈRhÈI
84.9(1)
92.67(7)
91.5(1)
175.9(1)
90.9(2)
166.59(3)
83.34(6)
90.43(2)
P(2)ÈRhÈO(1)
P(2)ÈRhÈC(21)
P(2)ÈRhÈC(27)
RhÈC(27)ÈO(2)
P(1)ÈC(1)ÈC(2)
C(1)ÈC(2)ÈO(1)
C(2)ÈO(1)ÈRh
2
3
Ðnal product.
176.1(1)
116.8(3)
123.7(3)
117.9(1)
Our results show that 1 readily adds a variety of XI-type
substrates to give stable oxidative addition products, resulting
in all cases from a net trans addition of XI. For X \ Me and
Ph, the molecular structures were determined crystallo-
442
New J. Chem., 2000, 24, 437È445

View Article Online
graphically and show that for both 2 and 3 the rhodium atom
is placed in a distorted octahedral coordination sphere with
similar bond distances and angles within the two structures.
The shorter RhÈC(21) bond found in the phenyl analogue
[2.078(3) A, 3 vs. 2.104(6) A, 2] results from greater orbital
Method 1: A CD Cl solution of 2 (143 mmol) was intro-
2
2
duced into a 0.106 mm KBr cell and a CO pressure of 0.16
MPa was applied. Spectra were taken approximately every
hour on a digilab FTS80 IR spectrometer. Method 2: A
sample was prepared as described in the NMR section and at
various time intervals the reaction was arrested by releasing
overlap between the empty rhodium d orbital and the sp2
z2
hybrid orbital of the phenyl carbon. In 2 the RhÈC(21)H
the CO pressure. This solution was then placed into a CaF
IR cell and the spectrum was recorded. Both methods gave
3
bond is formed between the rhodium d orbital and the sp3
z2
2
hybrid orbital of the methyl carbon. The stronger bond of the
identical results, however the reaction proceeded more rapidly
with method 2 due to the greater CO pressure that is acces-
sible with the NMR tube and the greater surface area of
mixing between the gas and the liquid in the NMR tube.
former becomes important during the carbonylation studies
where CO insertion reactions do not occur. On the other
hand, if 2 is placed under 0.2 MPa carbon monoxide, insertion
occurs to give three isomers of the acetyl complex
[Rw hMPh PCHbC(bOz )PhNMC(O)MeN(I)(CO)(PPh )]
5.
2
3
Synthesis
Although the mechanism of insertion was not determined, it
likely occurs by formal methyl migration to a cis carbon mon-
oxide ligand, generating a dynamic 5-coordinate square pyr-
amidal intermediate; isomerization and coordination of
carbon monoxide results in the formation of the three isomers.
Formation of complex 1 by reductive elimination of acetyl
iodide was observed. If one assumes a concerted process for
the elimination of acetyl iodide from the cis isomers of 5, a cis
geometry of 5a and 5b and a trans geometry of 5c result. The
latter is the sole isomer left in solution at the end of the reac-
tion.
Published methods were used to prepare 1.9
[Rw h{Ph PCHbC(bOz )Ph}Me(I)(CO)(PPh )] 2. To 250
2
3
mg (0.358 mmol) of complex 1 dissolved in 5 mL of dichloro-
methane was added 224 lL (3.60 mmol) of MeI. After 1 h of
stirring, the light orange solution turned yellow; the volume
was reduced to 2 mL and diethyl ether added to precipitate
the yellow crystalline powder: 265 mg (89%); This compound
can be recrystallized from dichloromethaneÈdiethyl ether. IR
(CH Cl ): l(CO) 2046(vs), l(CbO) ] l(CbC) 1525(s) cm~1.
Interestingly, the reaction between 1 and acetyl chloride
also leads to the formation of three isomers, 6aÈc. These
isomers share similar spectroscopic properties with 5aÈc.
Isomers 6b and 6c are generated by isomerization of 6a, which
can be isolated in an impure state. If 6a is left in solution, it
2
2
1H NMR (CD Cl ): d 0.78 (m, 3H, CH ),5.29 [dd, 2J(P,H)
2
2
3
\ 5.4, 3J(Rh,H) \ 2.2 Hz, 1H, PCH], 7.2È8.0 (m, 30H, Ph).
13CM1HN NMR (CD Cl ): d 14.2 [dt, 1J(Rh,C) \ 21, 2J(P,C)
2
2
\ 3 Hz, CH ], 70.1 [dd, 1J(P,C) \ 67, 2J(Rh,C) \ 1 Hz,
3
PCH], 184.0 [d, 1J(Rh,C) \ 16, 2J(P,C) \ 7 Hz, PhCO], 187.2
isomerizes and decomposes to [RhCl(CO)(PPh ) ]; after for-
3 2
[dt, 1J(Rh,C) \ 60, 2J(P,C) \ 11 Hz, CO]. 31PM1HN NMR
(CD Cl ): d 14.5 [dd, PPh , 1J(Rh,P) \ 92 Hz], d 46.1 [dd,
mation, the isomers 6b and 6c also quickly decompose. The
decomposition pathway remains undetermined but clearly
involves loss of the enolate ligand and a redistribution of
ligands.
2
2
A
3
B
PCH, 1J(Rh,P) \ 89, 2J(P ,P ) \ 412 Hz].
A
B
[Rw h{Ph PCHbC(bOz )Ph}Ph(I)(CO)(PPh )] 3. To 226 mg
The acetyl complexes generated by reaction of 2 with CO
are signiÐcantly more stable than their chloride analogues,
which were synthesized directly by oxidative addition of acetyl
chloride to 1. This di†erence suggests the involvement of elec-
tronic e†ects, rather than steric considerations.
2
3
(0.321 mmol) of complex 1 was added 5 mL of PhI. A gentle
reÑux was applied for 2 h, after which time the yellow solution
darkened. The progress of this reaction was monitored by IR
and was complete when the CO stretch at 1979 cm~1 was
replaced by the new CO stretch at 2051 cm~1. Excess PhI was
removed by distillation to give a mixture of yellow crystals
and a brown yellow gum. The mixture was dissolved in a
minimum of dichloromethane and diethyl ether was added to
precipitate the yellow crystalline powder: 202 mg (77%). IR
(CH Cl ): l(CO) 2051(vs), l(CbO) ] l(CbC) 1525(s) cm~1.
Experimental
Reagents and physical measurements
All operations were performed in Schlenk-type Ñasks under
high purity argon although complexes 2È4, 5 and 6 appear to
be air stable. Solvents were dried and distilled under argon:
toluene and diethyl ether from sodiumÈbenzophenone,
dichloromethane over NaH, methanol, iodomethane, and
iodobenzene from 3 A molecular sieves. Acetyl chloride was
distilled prior to use. 1H NMR spectra were recorded on a FT
Bruker AC-F 200 NMR spectrometer that operates at 200
MHz. 31PM1HN NMR were recorded on a FT Bruker CXP
200 NMR spectrometer that operates at 81 MHz. Carbonyl-
ation studies were made using a high pressure NMR tube,
which contained ca. 148 mmol of complex 2 in 0.5 mL
CD Cl . The sample was degassed on the line three times by
2
2
1H NMR (CD Cl ): d 6.2È6.6 (m, 5H, Ph), 5.25 [dd, 2J(P,H)
2
2
\ 5.4, 3J(Rh,H) \ 3.5 Hz, 1H, PCH], 6.8È7.9 (m, 30H, Ph).
31PM1HN NMR (CD Cl ): d 13.9 [dd, PPh , 1J(Rh,P) \ 89
2
2
A
3
Hz], d 49.4 [dd, PCH, 1J(Rh,P) \ 87, 2J(P ,P ) \ 408 Hz].
B
A
B
[Rw h{Ph PCHbC(bOz )Ph}(I) (CO)(PPh )] 4. To 222 mg
2
2
3
(0.320 mmol) of complex 1 dissolved in 5 mL of dichloro-
methane was added 0.081 mg (0.320 mmol) of I . Upon addi-
2
tion the pale yellow solution turned red. After stirring for 30
min, the volume was reduced to 2 mL and diethyl ether was
added to precipitate the dark red crystalline powder: 262 mg
(86%). This compound can be recrystallized from
dichloromethaneÈdiethyl ether. IR (CH Cl ): l(CO) 2080(vs),
2
2
freezeÈpump thawing and then 0.25 MPa carbon monoxide
was added. Both 1H and 31PM1HN NMR spectra of the car-
bonylation reaction of 2 were taken every 1 to 4 h up to com-
pletion of the reaction (ca. 60 h). Chemical shifts (in ppm) are
referenced to deuterated solvent for 1H and 13CM1HN NMR
spectra and to external 85% phosphoric acid standard for
31PM1HN NMR spectra using the highÐeld positive convention
for reporting chemical shifts. IR spectra were recorded in the
4000È200 cm~1 region on a Perkin Elmer 883 IR spectro-
meter. Samples were prepared as Nujol mulls or in CD Cl
2
2
l(CbO) ] l(CbC) 1525(s) cm~1. 1H NMR (CD Cl ): d 5.45
2
2
[dd, 2J(P,H) \ 6.6, 3J(Rh,H) \ 2.4 Hz, 1H, PCH], 6.2È7.2 (m,
30H, Ph). 31PM1HN NMR (CD Cl ): d 1.3 [dd, PPh ,1J(Rh,
2
2
A
3
A
P) \ 79 Hz], d 34.9 [dd, PCH, 1J(Rh,P) \ 76, 2J(P ,P ) \
B
B
469 Hz].
[Rw h{Ph PCHbC(bOz )Ph}{C(O)Me}Cl(CO)(PPh )] 6a–c.
2
3
To 300 mg (0.431 mmol) of complex 1 dissolved in 7 mL of
dichloromethane was added 30 lL (0.422 mmol) of MeC(O)Cl.
After stirring for ca. 10 min, the solvent was quickly removed
by vacuum techniques to give 311 mg (93%) of a yellow Ñaky
2
2
solution using CaF cells. IR spectra of the carbonylation
2
reaction of 2 were taken using two di†erent methods.
New J. Chem., 2000, 24, 437È445
443

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Navarro, I. Pascual and E. P. Urriolabeitia, J. Chem. Soc., Dalton
T rans., 1997, 763; ( f ) P. Crochet, B. Demerseman, M. I. Vallejo,
M. P. Gamasa, J. Gimeno, J. Borge and S. GarciaÈGranda,
Organometallics, 1997, 16, 5406.
solid. This compound cannot be recrystallized due to its insta-
bility in solution and is always contaminated with small quan-
tities of decomposition products. IR (CH Cl ): l(CO)
2
2
2075(vs), 1675 (vs), l(CbO) ] l(CbC) 1525(s) cm~1. 1H
NMR (CD Cl ): 6a, d 2.19 [s, C(O)CH ],5.42 [dd, 2J(P,H)
2
3
2
2
3
\ 5.4, 3J(Rh,H) \ 2.2 Hz, PCH], 7.2È8.0 (m, 30H, Ph).
31PM1HN NMR (CD Cl ): d 11.7 [dd, PPh , 1J(Rh,P) \ 100
2
2
A
3
Hz], d 45.0 [dd, PCH, 1J(Rh,P) \ 95, 2J(P ,P ) \ 347 Hz].
B
A
B
6b, 31PM1HN NMR (CD Cl ): d 24.4 [dd, PPh ,1J(Rh,P)
2
2
A
3
\ 93 Hz], d 42.9 [dd, PCH, 1J(Rh,P) \ 91, 2J(P ,P ) \ 312
B
A
B
Hz]. 6c, 31PM1HN NMR (CD Cl ): d 18.5 [dd, PPh ,1J(Rh,
2
2
A
3
A
P) \ 100 Hz], d 45.1 [dd, PCH, 1J(Rh,P) \ 95, 2J(P ,P ) \
B
B
344 Hz].
[Rw h{Ph PCHbC(bOz )Ph}Me(CO)(PPh )](OSO CF ) 7.
2
3
2
3
To 300 mg (0.431 mmol) of complex 2 dissolved in 50 mL of
dichloromethane was added 440 mg (1.71 mmol) solid
AgOSO CF . After 5 h of stirring, the yellow solution dark-
4
5
P. Braunstein, Y. Chauvin, S. Mercier, L. Saussine, A. DeCian
and J. Fischer, J. Chem. Soc., Chem Commun., 1994, 2203.
K. A. O. Starzewski and J. Witte, Angew. Chem., Int. Ed. Engl.,
1987, 26, 63.
2
3
ened and AgI precipitated. The solution was Ðltered over
Celite and reduced to dryness to give a Ñaky yellow solid. The
formation of this complex was accompanied by a small
amount of [MePPh ]I: 185 mg (51%). IR (CH Cl ): l(CO)
2090(vs), l(CbO) ] l(CbC) 1550(s), v(OTf) 1280(vs) cm~1.
1H NMR (CD Cl ): d 1.55 (br s, 3H, CH ), 5.13 [d, 2J(P,H)
\ 7 Hz, 1H, PCH], 6.9È8.0 (m, 30H, Ph). 31PM1HN NMR
(CD Cl ): d 15.6 (br s), d 55.8 [d, 1J(Rh,P ) \ 129 Hz].
6
7
U. Klabunde and S. D. Ittel, J. Mol. Catal., 1987, 41, 123.
K. A. O. Starzewski, in Ziegler Catalysts, eds. G. Fink, R.
Mulhaupt and H. H. Brintzinger, Springer Verlag, Berlin, 1995.
(a) P. Braunstein, J. Pietsch, Y. Chauvin, S. Mercier, L. Saussine,
A. DeCian and J. Fischer, J. Chem. Soc., Dalton T rans., 1996,
3571; (b) J. Andrieu, P. Braunstein and F. Naud, J. Chem. Soc.,
Dalton T rans., 1996, 2903; (c) P. Braunstein, Y. Chauvin, J.
Nahring, Y. Dusausoy, D. Bayeul, A. Tiripicchio and F. Uggo-
zoli, J. Chem. Soc., Dalton T rans., 1995, 851; (d) P. Braunstein, Y.
Chauvin, J. Nahring, A. DeCian and J. Fischer, J. Chem. Soc.,
Dalton T rans., 1995, 863.
3
2 2
2
2
3
8
2
2
A
B
B
Crystal structure determinations
Crystal data for 1. C
H
O P Rh É 0.5Et O, M \ 733.6,
39 31 2 2
2
monoclinic, space group P2 /n, a \ 13.864(3), b \ 8.859(2),
1
c \ 29.696(6) A, b \ 101.27(3)¡, U \ 3577.0(13) A
Ž
3, Z \ 4,
9
P. Braunstein, Y. Chauvin, J. Nahring, A. DeCian, J. Fischer, A.
Tiripicchio and F. Uggozoli, Organometallics, 1996, 15, 5551.
k(Mo-K ) \ 0.602 mm~1, T \ 293 K. A total of 25 660 reÑec-
a
tions with 6624 [R(int) \ 0.0536] independent reÑections were
10 D. N. Lawson, J. A. Osborn and G. Wilkinson, J. Chem. Soc. A,
1966, 1733.
collected, with 5690 reÑections having F [ 4p(F ). R \ 0.0365
o
o
11 A. J. Deeming and B. L. Shaw, J. Chem. Soc. A, 1969, 598.
12 G. Deganello, P. Uguagliati, B. Crociani and U. Belluco, J. Chem.
Soc. A, 1969, 2726.
13 D. Forster, J. Am. Chem. Soc., 1975, 97, 951.
14 S. Franks, F. R. Hartley and J. R. ChipperÐeld, Inorg. Chem.,
1981, 20, 3238.
[I [ 2p(I)], wR \ 0.1066 (all data).39
2
Crystal data for 2. C
H O P RhI, M \ 838.5, mono-
40 34 2 2
clinic, space group P2 /n, a \ 12.054(3), b \ 24.130(3),
1
c \ 12.213(3) A, b \ 92.25(2)¡ U \ 3549(2) A
Ž
3, Z \ 4, k(Mo-
K ) \ 1.455 mm~1, T \ 294 K. A total of 8297 reÑections
15 (a) J. R. Dilworth, J. R. Miller, N. Wheatley, M. J. Baker and J.
G. Sunley, J. Chem. Soc., Chem. Commun., 1995, 1579; (b) P. M.
Maitlis, A. Haynes, G. J. Sunley and M. J. Howard, J. Chem.
Soc., Dalton T rans., 1996, 2187; (c) J. Rankin, A. C. Benyei, A. D.
Poole and D. J. ColeÈHamilton, J. Chem. Soc., Dalton T rans.,
1999, 3771; (d) L. Gonsalvi, H. Adams, G. J. Sunley, E. Ditzel and
A. Haynes, J. Am. Chem. Soc., 1999, 121, 11233.
16 S. S. Basson, J. G. Leipoldt and J. T. Nel, Inorg. Chim. Acta,
1984, 84, 167.
a
with 4491 [R(int) \ 0.032] independent reÑections were col-
lected with 4991 reÑections having I [ 3p(I). R(F) \ 0.039,
Rw(F) \ 0.055.40
Crystal data for 3. C
H O P RhI, M \ 900.5, ortho-
45 36 2 2
rhombic, space group Pna2 , a \ 17.887(5), b \ 18.538(5),
1
c \ 11.515(5) A, U \ 3818(3) A
Ž
3, Z \ 4, k(Mo-K ) \ 1.377
a
17 J. A. Venter, J. G. Leipoldt and R. van Eldick, Inorg. Chem., 1991,
30, 2207.
mm~1, T \ 294 K. A total of 6390 reÑections were collected
with 5141 reÑections having I [ 3p(I). R(F) \ 0.022,
Rw(F) \ 0.027.40 The absolute structure was determined by
reÐning FlackÏs x parameter.
18 G. J. J. Steyn, A. Roodt and J. G. Leipoldt, Inorg. Chem., 1992,
31, 3477.
19 M. Cano, J. V. Heras, M. A. Lobo, E. Pinilla and M. A. Monge,
Polyhedron, 1992, 11, 2679.
CCDC reference number 440/178. See http://www.rsc.org/
suppdata/nj/b0/b000961j/ for crystallographic Ðles in .cif
format.
20 (a) Y. S. Varshavsky, T. G. Cherkasova, N. A. Buzina and L. S.
Bresler, J. Organomet. Chem., 1994, 464, 239; (b) M. R. Galding,
T. G. Cherkasova, Y. S. Varshavsky, L. V. Osetrova and A.
Roodt, Rhodium Express, 1995, 36.
Notes and references
21 Crystal data for 4:
C H O P RhI , M \ 950.34, crystal
39 31 2 2
2
1
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Berno, P. Braunstein, C. Floriani, A. ChiesiÈVilla and C. Guas-
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S. Coco Cea, M. I. Bruce, B. W. Skelton and A. H. White, J.
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system monoclinic, space group P2 /c, a \ 13.317(2),
1
b \ 34.898(6), c \ 16.655 (3) A, b \ 90.22(1)¡, U \ 7740(2) A
Ž
3,
Z \ 8, D \ 1.747 g cm~3, k(MoK ) \ 2.290 mm~1, T \ 293 K.
c
a
22 M. J. Baker, M. F. Giles, A. G. Orpen, M. J. Taylor and R. J.
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31 The synthesis of this compound is reported in the Experimental
section and it was only characterized by spectroscopic methods
due to puriÐcation and crystallization problems.
New J. Chem., 2000, 24, 437È445
445