Synthesis and transition metal chemistry of 'phosphomide' ligands: A comparison of the reactivity and electronic properties of diphenyl-P-perfluoro-octanoyl-phosphine, P-acetyl-dyphenylphophine and P-anisoyl-diphenylphosphine. X-ray crystal structure of [RhCp*(Ph2PC(O)CH3)Cl2]

Article abstract of DOI:10.1016/S0022-328X(02)02152-6

A convenient synthesis of several 'phosphomide' ligands (P adjacent to carbonyl group) from secondary phosphines is reported. The new anisoyl substituted phosphines are considerable more stable to hydrolysis, and are stronger σ-donor ligands than P-acetyldiphenylphosphine as determined by the measurement of ν(CO) for the corresponding rhodium carbonyl complexes trans - [RhL2(CO)Cl]. In contrast, a new phosphomide derived from perfluoro-octanoyl chloride was found to be a highly unstable, electron poor π-acceptor ligand. The crystal structure of [RhCp*Cl₂{Ph₂PC(O)CH₃}] showed a normal pseudo-octahedral pianostool molecular geometry with a Rh-P bond length of 2.3186(5) A?. The extra stability observed for the P-anisoyl phosphomides has led us to apply this class of ligand in rhodium catalysed hydroformylation for the first time.

Full text of DOI:10.1016/S0022-328X(02)02152-6

Journal of Organometallic Chemistry 667 (2003) 112Á119
/
www.elsevier.com/locate/jorganchem
Synthesis and transition metal chemistry of ‘phosphomide’ ligands: a
comparison of the reactivity and electronic properties of diphenyl-P-
perfluoro-octanoyl-phosphine, P-acetyl-diphenylphosphine and P-
anisoyl-diphenylphosphine. X-ray crystal structure of
[RhCp*(Ph2PC(O)CH3)Cl2]
R. Angharad Baber, Matthew L. Clarke *, A. Guy Orpen, David A. Ratcliffe
University of Bristol, School of Chemistry, Bristol BS8 1TS, UK
Received 5 August 2002; received in revised form 27 November 2002; accepted 30 November 2002
Abstract
A convenient synthesis of several ‘phosphomide’ ligands (P adjacent to carbonyl group) from secondary phosphines is reported.
The new anisoyl substituted phosphines are considerable more stable to hydrolysis, and are stronger s-donor ligands than P-acetyl-
diphenylphosphine as determined by the measurement of n(CO) for the corresponding rhodium carbonyl complexes trans-
[RhL2(CO)Cl]. In contrast, a new phosphomide derived from perfluoro-octanoyl chloride was found to be a highly unstable,
electron poor p-acceptor ligand. The crystal structure of [RhCp*Cl2{Ph2PC(O)CH3}] showed a normal pseudo-octahedral piano-
˚
P bond length of 2.3186(5) A. The extra stability observed for the P-anisoyl phosphomides has
stool molecular geometry with a RhÃ
/
led us to apply this class of ligand in rhodium catalysed hydroformylation for the first time.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Co-ordination chemistry; Hydroformylation; Phosphines; Rhodium complexes
1. Introduction
applications in catalysis [2,3]. The chemistry of fluoro-
carbylphosphines has also been a subject of considerable
interest in the last 10 years [4]. Phosphorus ligands that
contain the phosphorus adjacent to a carbonyl group
have been almost completely neglected in organometal-
lic chemistry and catalysis. This may stem from concerns
Phosphorus ligands play an enormously important
role in catalysis and organometallic chemistry. Subtle
changes in ligand structure often leads to improved
catalytic processes and organometallic complexes with
interesting properties. The synthesis of new types of
phosphorus ligands with unusual stereo-electronic prop-
erties is therefore an important goal. In particular, there
is currently great interest in p-accepting phosphorus
ligands in both organometallic chemistry and catalysis.
Electron withdrawing phosphite ligands are well estab-
lished as ligands of choice in several catalytic reactions
[1]. Phospha-benzenes and some p-accepting phosphino-
amines are more recent discoveries that are finding
regarding the stability of the PÃ/C bond, which has been
shown to undergo degradation reactions in the presence
of water or oxygen [5]. We envisaged that one of the
consequences of a carbonyl group adjacent to a
phosphorus atom would be an inductive electron with-
drawing effect, and a tendency for the phosphorus lone
pair to delocalise towards the carbonyl group (as shown
below). In this paper, we report our initial efforts in
* Corresponding author. Tel.:
1179290509.
ꢀ
/
44-1179546341; fax:
ꢀ/44-
E-mail address: matt.clarke@bristol.ac.uk (M.L. Clarke).
Fig. 1.
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 1 5 2 - 6

R. Angharad Baber et al. / Journal of Organometallic Chemistry 667 (2003) 112Á
/119
113
developing the transition metal and catalytic chemistry
of phosphomide ligands.
2. Results and discussion
Scheme 2.
A glance through the literature suggests that phos-
phomides are most effectively prepared from a tri-
methylsilylphosphine and acid chloride [6]. Acetyl-
diphenylphosphine has also been prepared by the
reaction of diphenylphosphine with ketene [7], or by
the reaction of various metallated phosphides with
acetyl chloride [8].
We felt that the reaction of an acid chloride with a
secondary phosphine would be a very mild, efficient
method to form a PÃ
/
C bond, thus allowing easy access
to a range of interesting phosphorus ligands. Moreover,
there are now many functionalised acid chlorides and
primary or secondary phosphines commercially avail-
able, and this method of synthesis should be capable of
tolerating a variety of functional groups. A simple and
quantitative ligand synthesis is very desirable for rapid
catalytic screening. We have found that reaction of
acetyl chloride with diphenylphosphine in the presence
of triethylamine immediately gives a white precipitate
Fig. 2. 31P{1H} NMR spectrum of Ph2PC(O)(CF2)6CF3, (4).
contribution from ‘through space’ interaction between
the bending fluorinated tail. The 31P-NMR spectrum is
an apparent 21 line signal is derived from a ‘triplet of
triplet of triplets’ splitting pattern (Fig. 1). Peak
intensities are fully consistent with this being a simple
first order spectrum in which 6 lines are hidden (Section
3).
(Et3N×
/
HCl) and a bright yellow solution of P-acetyl-
diphenylphosphine as the only phosphorus-containing
product. We have also prepared ether functionalised
phosphomides, (1)Á
/
(3) as we were intrigued by a recent
Delocalisation of the phosphorus lone pair towards
the carbonyl group (c.f. low nucleophilicity of amides)
or conjugation between carbonyl group and phosphorus
antibonding/3d hybrid orbitals [7] has been observed in
some of the fundamental examples of phosphomides
paper that suggested hemilabile PfflO phosphine ligands
may have a positive effect on both activity and
selectivity in rhodium catalysed hydroformylation of
olefins [9]. The reactions between o-anisoylchloride and
a range of secondary phosphines proceeded smoothly to
give the new phosphomides in essentially quantitative
yield and high purity by filtration and removal of
solvent Scheme 1.
reported to date and is reflected in the CÄ
frequency being found in the same region as amides
(n(CO) of Ph2PC(O)CH3ꢁ
1670 cmꢂ1). However, the
/O stretching
/
IR spectra of (1), (2) and (3) show a medium bands at
1781, 1739 and 1730 cmꢂ1, respectively which we assign
Diphenyl-perfluoro-octanoylphosphine could also be
prepared cleanly from readily available diphenylpho-
sphine, perfluoro-octanoylchloride and pyridine (or by
reaction of Ph2PSiMe3 with the acid chloride). Phos-
phines containing perfluorinated alkyl chains are cur-
rently attracting considerable attention as a result of
their applications in catalysis in perfluorinated solvent
systems and supercritical CO2 [4] Scheme 2.
as the CÄ
/
O stretch. We have assigned the strong doublet
band at ca. 1625 and 1595 cmꢂ1 as aromatic CÃ
/C
vibrations, as these are observed in this region for other
derivatives of anisoic acid. This is at significantly higher
wavenumber than in many amides (e.g. n(CO) of Et2NÁ
/
anisoylꢁ
/
1640 cmꢂ1) [10], and may reflect that the
phosphorus lone pair is not delocalised onto the
carbonyl group to a measurable extent. The position
of n(CO) in the IR spectrum of (4) (1686 cmꢂ1) suggest
that the phosphorus lone pair is partially delocalised
into the carbonyl group.
Perfluoroalkylphosphines frequently show long range
PÁF coupling in their NMR spectra, and (4) is no
/
exception. The longest range couplings may contain a
The series of phosphomide ligands we have prepared
also all differ in their sensitivity to moisture. Acetyl-
diphenylphosphine is instantly hydrolysed/alcoholysed
on treatment with water or methanol, respectively to
give the secondary phosphine (detected by 31P and
31P{1H} NMR) and presumably acetic acid or methyl
Scheme 1.

114
R. Angharad Baber et al. / Journal of Organometallic Chemistry 667 (2003) 112Á119
/
acetate. Although the cyclohexyl-substituted ligand is
somewhat oxygen sensitive, ligands (1) and (2) appear
stable to air, moisture or methanol for several days. It is
only on addition of p-toluenesulfonic acid to a metha-
nolic solution of (2), that extensive decomposition takes
place (within hours). One possible explanation for this
extra stability may stem from steric shielding from the
methoxy group. Indeed, this may also prevent the co-
planar orientation between phosphorus lone pair and
carbonyl group required for conjugation/delocalisation.
Alternatively, aryl phosphomides may have increased
stability w.r.t. alkyl phosphomides. The perfluorinated
ligand (4) is particularly sensitive, and is hydrolysed
within seconds of being exposed to the atmosphere, even
in the solid state. Presumably, the electronegative
perfluorinated chain strongly activates the carbonyl
group towards nucleophillic attack by adventitious
Scheme 3.
n(CO) trans-[Rh[Ph3P]2(CO)Cl]ꢁ
1965 cmꢂ1]. An in-
/
crease in the position of n(CO) for the carbonyl group
within the phosphomide on co-ordination to the metal is
also observed. Reaction of anisoyldiphenylphosphine
with [Rh(CO)2Cl]2 also gave the desired complex trans-
[Rh(Ph2Panisoyl)2Rh(CO)Cl], (7). The value of n(CO)
(1974 cmꢂ1) for the carbonyl ligand in this complex
suggests that the anisoyl group is less electron with-
drawing than the acetyl group, possible due to the steric
requirements of the PÃ
The band associated with the PÃ
tively assigned at 1725 cmꢂ1, but is of similar intensity
to the CÃC overtone bands that are also observed in this
region.
We have also studied the reactions of the diphenyl-
phosphino-substituted series of ligands with
/
CÄ/O bond as described above.
/
CÄO bond is tenta-
/
water. It remains to be seen if the PÃ
be transformed to other functional groups without PÃ
bond breakage.
/
CÄ
/
O bond can
/C
/
We have speculated on the electronic properties of the
free phosphomide ligands but also wished to investigate
the nature of MÃ/P bonding in transition metal com-
[RhCp*Cl2]2. All of the ligands react in the expected
way to produce complexes of type [RhCp*Cl2(h1-L)].
However, the reaction with the perfluorinated ligand is
unusually slow requiring a couple of hours to go to
completion Scheme 4.
All of the complexes show doublets in their 31P-NMR
spectra. The resonance’s are shifted ca. 30 ppm down-
plexes of phosphomides. There is very little is known
about the organometallic chemistry of this type of
ligand [11,12], so we have studied the reactions of the
diphenylphosphino-substituted ligands with organome-
tallic Rh(I) and Rh(III) precursors. We report here the
preparation of the first rhodium carbonyl complexes of
phosphomides, (5), (6) and (7), which has allowed us to
evaluate the s-donor/p-acceptor properties of these
ligands. These were prepared from [Rh(CO)2Cl]2 as
described in Scheme 3. The complexes were readily
isolated in high purity and yield as yellow solids. The
field from the free ligands. The PÁF couplings are not
resolvable in the rhodium complexes of ligand (4). The
1
magnitude of JPÁRh is somewhat larger than those
/
observed in complexes (5)Á
Rh(III) complexes. It is more difficult to assign the PÃ
CÄO bands in the IR spectra of these complexes as they
are of reduced intensity. However, the possibility of
delocalisation within the PÃCÄO bond is clearly less
/(7) as is expected for these
1
/
values of JPÁRh are fairly typical for this type of
complex and show the expected downfield co-ordination
/
shift (Ddꢀ
/
30 ppm) in going from free ligand to Rh(I)
complex. The values of n(CO) for the carbonyl ligand in
trans-[Rh(Ph2Pacetyl)2(CO)Cl] (1984 cmꢂ1) is consis-
tent with the acetyl group acting as a very strongly
electron withdrawing group. This is presumably due to
inductive effects caused by the electronegative carbonyl
/
/
likely if the phosphomides are complexed to a transition
metal. The rhodium complexes in this study show
similar relative stabilities to those found in the free
ligands: Complex (9) slowly and selectively decomposed
to [RhCp*Cl2(h1-PPh2H)] which was easily identified by
the distinctive doublet of doublets in it’s 31P (1H
coupled) NMR spectrum [14]. In contrast,
functionality. The value of n(PÃ
/
CO) in the IR spectrum
is increased by 30 cmꢂ1 on co-ordination to the metal,
which is consistent with the resonance structure contain-
ing CÃ/O single bonds making a lesser contribution in
the metal complexes of acetyl-diphenylphosphine. The
position of n(CO) of the carbon monoxide ligand in
complex (6) is at 1990 cmꢂ1. This value suggests that the
perfluoro-octanoyl group does indeed have a pro-
nounced effect on the p-accepting properties of ligand
(4). The position of this band shows that the perfluoro-
octanoyl substituent has a similar effect to very strongly
electron withdrawing pyrrolyl substituent. [n(CO) trans-
[Rh(Ph2P(pyrrolyl)(CO)Cl]ꢁ
trans-[Rh[Ph2P(C6F5)]2(CO)Cl]ꢁ
/
1990 cmꢂ1 [3]; n(CO)
1974 [13];
cmꢂ1
/
Scheme 4.

R. Angharad Baber et al. / Journal of Organometallic Chemistry 667 (2003) 112Á
/119
115
Scheme 5.
[Cp*RhCl2(h1-1)] and [Cp*RhCl2(h1-Ph2PC(O)CH3)]
were found to be air stable solids Scheme 5.
Crystals of complex (8) were grown by layering a
CH2Cl2 solution with diethyl ether. The X-ray structure
of complex (8) confirms the spectroscopic data that
show the phosphomides co-ordinated to Rh(III) in a
monodentate fashion. The complex has the expected
octahedral pianostool structure with the RhÃ
/
C bonds
varying in length depending on whether they are trans to
Fig. 3. Molecular structure of [Cp*RhCl2{Ph2PC(O)CH3}] . All
hydrogen atoms have been omitted for clarity. Important molecular
˚
parameters: bond lengths (A) Rh(1)-P(1) 2.3188(5), Rh(1)-Cl(1)
the phosphomide or chloride ligands. From the 21 X-ray
structures of transition metal that contain PÃ
bonds in the Cambridge crystallographic database, the
average PÃC bond length of the PÃCÄO substituent is
1.87 A. The PÃC bond length within the structure
/
CÄ
/
O
2.4132(6), Rh(1)-Cl(2) 2.4060(6), P(1)-C(1) 1.833(2), P(1)-C(12)
1.816(2), P(1)-C(23) 1.917(2); bond angles (8) P(1)-Rh(1)-Cl(1)
91.11(2), P(1)-Rh(1)-Cl(2) 84.68(2), Cl(1)-Rh(1)-Cl(2) 93.33(2).
/
/
/
˚
/
˚
reported here (1.917(2) A) is somewhat longer than in
any of the structures previously reported, which may be
consistent with our observations regarding the stability
of this phosphomide and its metal complexes, which are
rates of reaction and yield and selectivity are shown in
Table 1 and Scheme 6.
The new phosphomides ligands do give active rho-
dium catalysts for hydroformylation of hex-1-ene.
However, the reactions were catalysed more efficiently
using the commercially applied catalyst Rh(CO)2acac/
PPh3. Graphs of syngas uptake for the first 2 h of the
readily cleaved by adventitious water. In (8) this PÃ
length is significantly longer than the two PÃPh bonds
(Fig. 2). This implies little contribution of a resonance
structure that involves a PÄCÃ
Oꢂ bond in phospho-
/C
/
/
/
mide ligands. A structural comparison between free
ligands and metal complexes has not proved possible
due to the lack of crystallinity for the ligands prepared
so far. The RhÃ
/
P and RhÃ/Cl bond lengths are similar to
other [RhCp*Cl2(PR3)] complexes that we have re-
ported [15] (Fig. 3).
The extra stability of ligands (1), (2) and (3) suggested
to us that these ligands might be sufficiently stable for
catalytic applications. Hydroformylation of olefins is
one of the most important homogeneously catalysed
reactions in industry and there is currently considerable
Scheme 6.
Table 1
Hydroformylation of hex-1-ene using new phosphomide ligands and
Rh(acac)(CO)2 as catalyst
interest in obtaining structureÁactivity/selectivity rela-
/
a,b
a
c
tionships for the wide array of phosphine ligands that
are known. A study of this nature may, in addition to
improving understanding, lead to improved ligand
modified catalysts for this reaction.
Somewhat surprisingly, phosphomides are quite pos-
sibly unreported as ligands for homogeneous catalysis.
Catalysts prepared in situ from the new ligands and
[Rh(acac)(CO)2] were tested in hydroformylation of hex-
1-ene. The two phosphomides were tested under the
same conditions alongside triphenylphosphine. Rates of
reaction could be estimated by following syngas uptake
over time. Yield and selectivity were determined by G.
C. M. S. at the end of the 3 h reaction period. Relative
Ligand
Conversion of hexene (%)
n:i
T.O.F.
PPh3
(1)
(2)
95
60
77
85
0
2.9
2.6
2.0
2.1
ND
380
ND
157
200
ND
(3)
(4)
Reactions were carried out under identical conditions: 60 8C, 20
bar CO/H2 (1:1), 3 h, 0.2 mol% catalyst, L/Rhꢁ4.5. The values are
taken from the first 50% of the reaction where gas uptake is linear (mol
/
prod/molscatalysts/h). NDꢁ
/
not determined.
determined by G. C. M. S. using biphenyl as an internal standard.
a
b
no other products except aldehydes could be detected by G. C. M.
S.
c
calculated from a graph of syngas uptake over time.

116
R. Angharad Baber et al. / Journal of Organometallic Chemistry 667 (2003) 112Á119
/
reaction show gas consumption is still proceeding for the
phosphomides, which suggests that complete conversion
would be reached under more forcing conditions or
longer reaction times. G. C. M. S. analysis of the
reaction mixtures at the end of the reaction showed all
three catalysts showed good selectivity towards alde-
hydes, while the two phosphomide derived catalysts
show a greater proportion of branched aldehyde than
triphenylphosphine catalysts. Catalysts derived from the
perfluorinated ligand (4), do not show any catalytic
activity in hydroformylation, presumably due to the
intrinsic instability of the ligand.
lytical Laboratory. E.I. and F.A.B. mass spectra were
recorded by the University of Bristol mass spectrometry
service using a ‘VG Analytical Autospec’ mass spectro-
meter. IR were recorded on NaCl discs as CH2Cl2
solutions (rhodium complexes) or neat thin films
(ligands), on a PerkinÁElmer 1600 Series FTIR (samples
/
were prepared in air immediately prior to running
spectra). All other chemicals were obtained commer-
cially (Aldrich, Lancaster, Fluorochem).
3.2. Ph2PCOCH3
Since (2) gives a greater proportion of branched
products than triphenylphosphine, we have also tested
this ligand in hydroformylation of 4-vinylanisole: a
reaction in which the branched isomer is favoured and
of more synthetic value. We have found that phospho-
mide (2) gives high conversions (80%) of vinylanisole to
give the desired branched 2-aryl-propanal products with
a branched to linear ratio of ca. 19:1. A triphenylpho-
sphine based system gave 95% yield of 2-aryl-propanal
with branched to linear ratio of 13:1 under similar
conditions.
Acetyl chloride (0.220 g, 2.81 mmol) was added
dropwise over ca. 20 min to a solution of diphenylpho-
sphine (0.524 g, 2.81 mmol) and triethylamine (0.284 g,
2.81 mmol) in diethyl ether (20 ml) and stirred for 2 h.
The reaction mixture was filtered to remove the
triethylamine hydrochloride and solvent was removed
in vacuo leaving a yellow oil in essentially quantitative
yield. This compound has been reported previously. It
was identified by comparison of NMR and MS data
with those reported in Refs. [7,8]. 31P-NMR (121.4
MHz, CDCl3), d 19. IR n(CO)ꢁ
/
1670 cmꢂ1. EIMS: 320
Although this new ligand modified catalyst offers no
real advantages in hydroformylation, we have demon-
strated that phosphomides can be used as ligands for
this reaction. Since these ligands are so readily prepared,
it should be straightforward to prepare a family of
mono-, di- and hemi-labile phosphines that can be
screened as ligands in homogeneous catalysis. We have
also shown that the presence of the carbonyl group does
not interfere with the ability of the phosphorus to act as
a ligand for rhodium complexes, and that the stability of
the phosphomide may be strongly influenced by the
substituents that are nearby the carbonyl group. We are
currently investigating the scope of the primary/second-
(Mꢀ).
/
3.3. Ph2Panisoyl, (1)
o-Anisoyl chloride (0.480 g, 2.813 mmol) was added
dropwise over ca. 20 min to a solution of diphenylpho-
sphine (0.524 g, 2.81 mmol) and triethylamine (0.284 g,
2.81 mmol) in diethyl ether (20 ml) and stirred for 2 h.
The reaction mixture was filtered to remove the
triethylamine hydrochloride and solvent was removed
in vacuo leaving a yellow oil in essentially quantitative
yield. This compound has been reported previously by
the addition of trimethylsilyldiphenylphosphine to ani-
soic acid in 37% yield. It was identified by comparison
of NMR and MS data with those reported in Ref. [16].
ary phosphineꢀacid chloride route for the synthesis of a
/
variety of phosphorus ligands, and applying them in
homogeneous catalysis.
31P-NMR (121.4 MHz, CDCl3), d 25. IR n(CO)ꢁ
/
1782
cmꢂ1. EIMS: 320 (Mꢀ
/).
3. Experimental
3.4. (NCCH2CH2)2Panisoyl, (2)
3.1. General
o-Anisoyl chloride (2.05 ml, 1.79 g, 10.5 mmol) was
added dropwise over ca. 20 min to a solution of
diethylcyanophosphine (1.47 g, 10.5 mmol) and triethy-
lamine (0.77 ml, 1.06 g, 10.5 mmol) in toluene (30 ml)
and stirred for 2 h. The reaction mixture was filtered to
remove the triethylamine hydrochloride and solvent was
removed in vacuo leaving a yellow oil (yield: 2.53 g, 9.2
mmol, 88%). This synthesis always gave material that
was of very high purity, as determined spectroscopically.
All manipulations were carried out under an atmo-
sphere of nitrogen, using standard Schlenk line techni-
ques, and at room temperature unless otherwise stated.
All solvents were dried and degassed by elution through
an alumina column impregnated with deoxygenating
catalysts under nitrogen, and stored under nitrogen. 31P-
NMR spectra were recorded using an Eclipse 300
spectrometer. H and 13C-NMR spectra were recorded
by the University of Bristol NMR Service using a
Lambda 300 MHz spectrometer. Chemical analyses
were performed by the School of Chemistry Microana-
1
IR n(CÄ
/
O): 1730 cm,ꢂ1 n(CN): 2248 cmꢂ1 31P-NMR
.
(121.4 MHz, CDCl3), d 9.6. 1H-NMR (400 MHz,
CDCl3), d 1.82 (2H, m, CH2CH2CN), 2.2 (2H, m,
CH2CH2CN), 2.42 (2H, m, CH2CH2CN), 2.54 (2H, m,

R. Angharad Baber et al. / Journal of Organometallic Chemistry 667 (2003) 112Á
/119
117
CH2CH2CN), 3.9 (3H, s, OCH3), 6.7Á
/
8.0 (4H, m,
the desired complex as the only product. Analytically
pure material was obtained by removing solvent and
aromatic). 13C-NMR (75.4 MHz, CDCl3), d 15.1,
20.7, 56.2, 112.3, 121.5 (m), 128.9, 135.1 (m), 158.5,
215.3. EIMS: Found: m/z 275 (MH)ꢀ requires 275.
washing the orange precipitate with diethyl ether (3ꢃ
ml). Yield: 40 mg, 6.42ꢃ
10ꢂ5 mol, 34%.
C29H26O3P2ClRh requires: C, 55.92; H, 4.21. Found:
C, 55.76; H, 3.96%. n(CÄ
O): 1984, 1699 cmꢂ1 31P-
NMR (121.4 MHz, CH2Cl2), d 42.3, (1JPÁRh
125 Hz).
1H-NMR (300 MHz, CDCl3), d 2.96, (6H, t. app., Jꢁ
2.2 Hz, C(O)CH3), 7.30 (12H, m, ArH), 8.3 (8H, m,
ArH). FABMS: 588 (MÃCl)ꢀ
/3
/
/
.
3.5. Cy2Panisoyl, (3)
ꢁ
/
/
o-Anisoyl chloride (0.74 ml, 0.85 g, 4.9 mmol) was
added dropwise over ca. 20 min to a solution of
dicyclohexylphosphine (1 ml, 0.98 g, 4.9 mmol) and
triethylamine (0.69 ml, 4.9 mmol) in toluene (20 ml) and
stirred for 2 h. The reaction mixture was filtered to
remove the triethylamine hydrochloride and solvent was
removed in vacuo leaving a yellow oil (yield: 1.49 g, 4.5
mmol, 91%). C20H29O2P requires: C, 72.26; H, 8.79.
/
/
.
3.8. Trans-[Rh(diphenyl-perfluoro-
octanoylphosphine)2(CO)Cl], (6)
Solid (RhCl2(CO)]2 (26 mg, 6.698ꢃ
added in one portion to a solution of ligand (1) ( 156 mg,
2.679ꢃ
10ꢂ6 mol) in THF. Removal of solvent and
/
10ꢂ5 mol) was
Found: C, 71.80; H, 9.35%. n(CÄ
NMR (121.4 MHz, CH2Cl2), d 32.1. 1H-NMR (300
MHz, CDCl3), d 1.0Á2.3 (12H, m, Cy), 3.8 (3H, s,
OCH3), 6.8Á7.7 (4H, m, aromatic). EIMS: Found: m/z
332 (Mꢀ).
/
O): 1739 cmꢂ1 31P-
.
/
drying in vacuo gave the desired compound in quanti-
tative yield as an air sensitive yellow powder.
/
/
Anal. C41H20F30P2O3Cl1Rh1 requires: C, 37.00; H,
1.51; Found: C, 37.25; H, 1.50. IR (nmax/cmꢂ1) 1990
(RhÃ
d 51.8 (d, JPÁRh
CDCl3), d: 6.7Á
7.6 (10H, ArH). 19F NMR (282.2 MHz,
C6D6) d: ꢂ81.1, (qnt, app., JFÁF 10.2 Hz), ꢂ109.1 (s,
br), ꢂ120.3 (s, br), ꢂ121.6 (s, br), ꢂ122.0 (s, br),
122.8 (s, br), ꢂ126.3 (s, br.).
/
CO), 1724 (PÃ
/
CO). 31P-NMR (121.4 MHz; C6D6):
3.6. Diphenyl-perfluoro-octanoylphosphine, (4)
ꢁ
131.9 Hz). 1H-NMR (300 MHz,
/
1
/
Neat diphenyl-trimethylsilylphosphine ( 0.516 ml,
2.02 mmol) was added dropwise to an ice cold solution
of perfluoro-octanoyl chloride (0.5 ml, 2.02 mmol) in
THF. After stirring for 1 h, all volatiles were removed in
vacuo to give a quantitative yield of the title compound
as an air sensitive, analytically pure white powder. This
ligand was also prepared in essentially quantitative yield
/
ꢁ
/
/
/
/
/
ꢂ
/
/
3.9. Trans-[Rh(Ph2Panisoyl)2(CO)Cl], (7)
Solid [Rh(CO)2Cl]2 (28 mg, 7.1ꢃ
10ꢂ5 mol) was
/
by the reaction of Ph2PÃ
/
H with the acid chloride under
added in one portion to a dichloromethane solution of
anisoyldiphenylphosphine (91 mg, 0.284 mmol in 5 ml
CH2Cl2). Removal of solvent gave the desired complex
in high purity as determined spectroscopically. How-
ever, samples isolated in this way always gave chemical
analyses that were too low for carbon (by c. 1%).
Layering a CH2Cl2 solution with diethyl ether gave a
few yellow crystals of the desired complex that analyses
similar conditions to those described for the other
phosphomides above.
Anal. C20H10F15P1O1 requires: C, 41.26; H, 1.73;
Found: C, 41.07; H, 1.71. IR (nmax/cmꢂ1) 1686 (CO).
31P-NMR (121.4 MHz; CDCl3): d 23.3 (21 lines, app.-
4
5
ttt) (3JPÁF
ꢁ
/
23.3, JPÁF
ꢁ
/
10.2, JPÁF
sities: septets (app.) are derived from tt
ꢁ5.6 Hz). Inten-
/
as the ether solvate. C41H34O5P2Cl1Rh×
C, 61.3; H, 5.15. Found: C, 62.1; H, 5.14%. n(CÄ
1976 cmꢂ1 31P-NMR (121.4 MHz, CH2Cl2) d 47.5,
(1JPÁRh 130 Hz). 1H-NMR (300 MHz, CDCl3), d 3.46
(6H, s, OMe), 6.75 (2H, d, Jꢁ8.3 Hz, 3-anisoylH), 6.97
(2H, t, Jꢁ7.5 Hz, 4-anisoylArH), 7.44 (14H, m, ArH),
7.71 (8H, m, ArH), 7.88 (2H, dd, Jꢁ1.7, 7.7 Hz,
6anisoylArH). FABMS 829 (MꢀNa)ꢀ, 778 (MÃCO)ꢀ
, 771 (MÃCOÃCl)ꢀ
/
Et2O requires:
/
O):
1 2 3 4 3 2 1
1 2 3 4 3 2 1
.
2 4 6 8 6 4 2
ꢁ
/
1H-NMR (300 MHz; C6D6): d 7.2Á
/
7.8 (10H, m,
82.6 tt (3Jꢁ
9 Hz),
/
ArH). 19F NMR (282.2 MHz, C6D6) d: ꢂ
10.0 Hz, 3Jꢁ
1.9 Hz), ꢂ115.5 qnt. App. Jꢁ
120.2(s, br.), 120.3(s, br.), 123.4(s, br.),
124.1(s., br.), ꢂ127.7 (m, br.) MS (FABꢀ) 601
(MꢀNaꢀ), 583 (MHꢀ).
/
/
/
/
/
/
/
ꢂ
/
ꢂ
/
ꢂ
/
/
/
/
/
ꢂ
/
/
/
/
/
/
.
/
/
/
3.10. [RhCp*Cl2(Ph2C(O)CH3)], (8)
3.7. Trans-[Rh(Ph2Pacetyl)2(CO)Cl], (5)
Solid [Rh(CO)2Cl]2 (37 mg, 9.53ꢃ
10ꢂ5 mol) was
To a Schlenk tube containing [Cp*RhCl2]2 (116 mg,
0.188 mmol) and Ph2PC(O)CH3 (86 mg, 0.377ꢃ
10ꢂ3
/
/
added in one portion to a dichloromethane solution of
acetyldiphenylphosphine (87 mg, 0.382 mmol in 5 ml
CH2Cl2). This immediately gave a solution containing
mol) was added CH2Cl2 (3 ml). The resulting solution
was stirred for 2 h prior to removal of solvent. NMR
spectroscopy revealed the desired complex in essentially

118
R. Angharad Baber et al. / Journal of Organometallic Chemistry 667 (2003) 112Á119
/
quantitiative yield and purity. Recrystallisation of some
of this product by layering a CH2Cl2 solution with
diethyl ether gave good quality red crystals suitable for
X-ray diffraction. C24H28P1O1Rh1Cl2 requires: C, 53.65;
rates were determined by measuring gas uptake over
time up to 50% conversion, and further confirmed by
GCÁMS analysis of the reaction products. The identities
/
of the reaction products were established by comparison
of retention times and mass spectra with authentic
samples.
H, 5.25. Found: C, 53.90; H, 5.56. n(Cꢁ
/
O): 1654 cmꢂ1
142
.
31P-NMR (121.4 MHz, CD2Cl2) d 39.3, (1JPÁRh
ꢁ
/
Hz). 1H-NMR (300 MHz, CDCl3), d: 1.4 (15H, d,
Rh(acac)CO2 (5.0 mg, 1.9ꢃ
/
10ꢂ5 mol, 0.2%), ligand
3
4JHÁP
ꢁ/3.5 Hz), 2.45 (3H, d, JHÁP
ꢁ
/
4.6 Hz), 7.4Á
/7.7
(8.6ꢃ
/
10ꢂ5 mol, 0.9%) biphenyl (0.468 g, 3.038 mmol)
(10H, m, ArH). FABMS: 501 (MÃ
/
Cl)ꢀ
/
.
in toluene (4 ml), were added to the autoclave which was
then flushed with syngas. The autoclave was then
pressurised (10 bar) and stirred at 60 8C for 1 h to
allow the catalyst to form. Hex-1-ene (1.2 ml) was
injected and the pressure adjusted to 20 bar. The gas
uptake was followed over time.
3.11. [RhCp*Cl2(Ph2C(O)(CF2)6CF3)], (9)
To a Schlenk tube containing [Cp*RhCl2]2 (41 mg,
6.61ꢃ
10ꢂ5 mol) and ligand (4) (77 mg, 1.322ꢃ10ꢂ4
/
/
mol) was added THF (3 ml) and CH2Cl2 (3 ml). After
heating to reflux, the resulting solution was stirred for 2
h (Longer reaction times lead to decomposition).
Removal of solvent gave the desired complex in
Hydroformylation of 4-vinylanisole was carried out
using the same apparatus using Rh(acac)CO2 (13.0 mg,
5.1ꢃ
/
10ꢂ5 mol, 1%), ligand (1.02ꢃ10ꢂ4 mol, 2%) in
/
C6D6 (4 ml). The reactions were carried out at 50 8C, 30
bar syngas for 16 h and analysed by 1H-NMR at the end
of the reaction time.
essentially
C30H25F15P1O1Rh1Cl2 requires: C, 40.43; H, 2.83.
Found: C, 40.91; H, 3.24. n(CÄ
O): 1730 cmꢂ1 31P-
NMR (121.4 MHz, CD2Cl2) d 45.5, (1JPÁRh
145 Hz).
1H-NMR (300 MHz, CDCl3), d 1.3 (15H, d, JHÁP
2.7
Hz), 7.3Á
7.9 (10H, m, ArH). 19F NMR (282.2 MHz,
C6D6) d: ꢂ
120.3 (s, br), ꢂ
quantitiative
yield
and
purity.
/
.
ꢁ
/
3.14. X-ray crystallography
ꢁ
/
/
X-ray diffraction experiments on 8 were carried out at
3
/
81.0 (t, br Jꢁ
/
10.0 Hz), ꢂ
122.3 (s, br), ꢂ
. This red
/
110.0 (s, br),
ꢂ100 8C on a Bruker SMART diffractometer. Crystal
/
data: red block, 0.2ꢃ
aꢁ11.9443(13), bꢁ
/
0.5ꢃ
/
0.5 mm3, C24H28Cl2OPRh;
˚
ꢂ
br), ꢂ
/
/
121.5 (s, br), ꢂ
/
/123.0 (s,
/
126.3 (m, br). FABMS: 855 (MÃ
/
Cl)ꢀ
/
/
/
15.492917, cꢁ
/
12.6695(14) A, bꢁ
/
solid slowly decomposed in air to [Cp*RhCl2(h1-
91.515(2)8, monoclinic, space group P21/n (No. 14),
Zꢁ4, Bruker SMART diffractometer scan,
MoÁ 0.71073 A, 24550 intensity data,
5366 unique, Rint 0.0381, 99.9% complete to uꢁ27.58,
absorption correction based on equivalent reflections,
R1ꢁ0.0232 [for 4335 reflections with I ꢀ2s(I)], 374
parameters, Largest difference map peak and hole 0.462
Ph2PH); 31P-NMR (121.4 MHz, CD2Cl2 1H coupled)
/
v
d 14.8, (dd, 1JPÁRh
d 13.5, (1JPÁRh
ꢁ
/
143 Hz, 1JPÁH
142 Hz).
ꢁ
/
388 Hz). Lit.14ꢁ
/
˚
/
Karadiation lꢁ
/
ꢁ
/
ꢁ
/
/
3.12. [RhCp*Cl2(Ph2Panisoyl)], (10)
/
/
To a Schlenk tube containing [Cp*RhCl2]2 (42 mg,
7.02ꢃ
10ꢂ5 mol) and Ph2Panisoyl (45 mg, 1.405ꢃ10ꢂ4
˚
and ꢂ
/
0.346 e Aꢂ3, wR2ꢁ
0.0530 for all data refined
/
against F2o with hydrogen atoms riding in calculated
positions.
/
/
mol) was added CH2Cl2 (3 ml). The resulting solution
was stirred for 2 h prior to removal of solvent. The red
ppte was washed with diethyl ether and dried in vacuo.
NMR spectroscopy revealed the desired complex in
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC 198449 for compound (8).
essentially
C24H28P1O1Rh1Cl2×
quantitiative
yield
0.2CH2Cl2 (solvent present in
and
purity.
/
NMR spectrum) requires: C, 56.16; H, 5.05. Found:
C, 55.33; H, 4.92. 31P-NMR (121.4 MHz, CD2Cl2) d:
Acknowledgements
40.1(1JPÁRh
ꢁ
141 Hz). 1H-NMR (300 MHz, CDCl3), d:
/
We would like to thank Prof. Paul Pringle (University
of Bristol) for useful discussions. We also wish to thank
the Leverhulme Trust and University of Bristol for
financial support.
4
1.5 (15H, d, JPÁRh
0.2 CH2Cl2), 6.48 (1H, d, Jꢁ
(1H, t, Jꢁ7.5 Hz, 4-anisoylH), 7.2Á
7.6 (1H, dd, Jꢁ1.7, 7.5 Hz, 6-anisoylH), 7.8 (4H, m,
ArH). FABMS: 593 (MÃCl).
ꢁ
/
3.3 Hz), 3.4 (3H, s), 5.3 (0.4H, s,
8.6 Hz, 3-anisoylH), 6.8
7.35 (7H, m, ArH),
/
/
/
/
/
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