New ligands for Rh-catalysed hydroformylation of 1-octene in supercritical carbon dioxide - X-ray structure of [Rh{PPh2(OC9H 19)}4]PF6

Article abstract of DOI:10.1002/ejic.200500790

The new P-donor ligands PPh_3-n(OC₉H ₁₉)_n (n = 3, 2, 1) containing branched alkyl chains were synthesised and their coordination to Rh^II and PdII studied. The X-ray structure of [Rh{PPh₂(OC<

Full text of DOI:10.1002/ejic.200500790

FULL PAPER
DOI: 10.1002/ejic.200500790
New Ligands for Rh-Catalysed Hydroformylation of 1-Octene in Supercritical
Carbon Dioxide – X-ray Structure of [Rh{PPh2(OC9H19)}4]PF6
Marta Giménez-Pedrós,[a] Ali Aghmiz,[a] Núria Ruiz,[a] and Anna M. Masdeu-Bultó*[a]
Keywords: Alkenes / Hydroformylation / P ligands / Rhodium / Supercritical fluids
The new P-donor ligands PPh3–n(OC9H19 n
)
(n = 3, 2, 1) con-
gated in supercritical carbon dioxide (scCO2) and toluene as
solvents. Although the catalytic systems are not soluble in
scCO2, they are active. The activities are higher in toluene
than in scCO2 but the selectivities for aldehydes in the case
of the phosphonite derivative are higher in the supercritical
medium than in toluene.
taining branched alkyl chains were synthesised and their co-
ordination to RhI and PdII studied. The X-ray structure of
[Rh{PPh2(OC9H19)}4]PF6 was determined. Reaction of the
[Rh(acac)(CO)2]/PPh3–n(OC9H19 n
5 atm and 80 °C in toluene led to the formation of [RhH(CO)-
{PPh3–n(OC9H19)n}3] as the main species. The Rh-catalysed
)
systems with CO/H2 at
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
hydroformylation of 1-octene with these ligands was investi-
crease the solubility of the catalytic systems. The most suc-
cessful approach is to introduce perfluoroalkyl chains in the
ligand.[5] However, the synthesis of perfluorinated ligands
is difficult and expensive.
Introduction
In the last few years supercritical carbon dioxide (scCO2)
has received growing attention as an alternative reaction
medium for homogeneous catalysis[1] as it is an environmen-
tally friendly and cheap solvent. More important, however,
are its gas-like properties, especially in reactions in which
the reactants are gases. scCO2 is highly miscible with gases
such as hydrogen and carbon monoxide (it can therefore
avoid the gas–liquid mass transfer) and is highly compress-
ible. It also has a low viscosity and therefore a high diffusiv-
ity. Moreover, its ability as an extraction solvent has proved
useful for separating the products from the catalysts with-
out the need for harsher conditions such as those used for
the distillation of higher alkenes.[2]
The catalytic hydroformylation of long-chain alkenes is
an interesting reaction for transforming alkenes into alde-
hydes using carbon monoxide and hydrogen.[3] The alde-
hydes obtained allow the synthesis of oxo alcohols used in
the detergent industry and as plasticizers in the polymer
industry. Rhodium catalysts associated with P-donor li-
gands are the most successful system for the hydrofor-
mylation of alkenes under mild conditions. Water can be
used as a “green” solvent in this reaction, but this process
is limited to short-chain alkenes (propene and 1-butene) be-
cause a certain degree of solubility of the alkene in water is
required.[4] scCO2 is a non-polar solvent in which alkenes
are soluble, but ligand modification is often needed to in-
Cole-Hamilton and co-workers obtained good activities
when they used alkylated phosphanes such as [Rh2(OAc)4]/
PEt3 systems, which are soluble in scCO2, in the hydrofor-
mylation of 1-hexene, but the n/iso ratios were modest (2.1–
2.6).[6] Ligands containing alkyl groups, preferably
branched, with a chain length of eight carbon atoms have
reportedly shown high solubility in supercritical carbon di-
oxide.[7] In the case of alkylphosphanes, such as P(C8H17)3,
the Rh systems were not soluble under the conditions
studied and the turnover frequency (TOF) was low (3–7 h–1,
8–20% conversion in 2 h), although the n/iso ratios were
high (up to 3.9).[6] When linear alkylated groups were intro-
duced into the aromatic rings [P(C6H4C6H13)3,
P(C6H4C10H21)3, and P(C6H4C16H33)3], the corresponding
rhodium systems, which are partially soluble in scCO2,
showed activities in the hydroformylation of 1-hexadecene
with average TOFs of 150, 350 and 20 h–1, respectively. This
correlated with a maximum solubility of the C10H21 deriva-
tive.[5c] Other scCO2-insoluble systems, such as P(OPh)3,
P(p-OC6H4-C9H19)3 and PPh2[CH2CH(CO2C16H33)CH2-
CO2C16H33], have been reported to show good activity in
the hydroformylation of 1-hexene. The advantage of insolu-
ble systems is that the products can be flushed away from
the insoluble catalyst system by taking advantage of the ex-
cellent extraction ability of scCO2.[8]
[a] Departament de Química Física i Inorgànica, Facultat de
Química, Universitat Rovira i Virgili,
The incorporation of tert-butyl substituents into the
alkyl chains of P-donor ligands has been reported to in-
crease their solubility in scCO2.[7,9] Introducing branched
chains in surfactants derived from sodium bis(2-ethyl-1-
hexyl)sulfosuccinate increases their solubility in scCO2.[10]
C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
Fax: +34-977-559-563
E-mail: annamaria.masdeu@urv.net
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2006, 1067–1075
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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M. Giménez-Pedrós, A. Aghmiz, N. Ruiz, A. M. Masdeu-Bultó
FULL PAPER
In this paper we present the synthesis of three new P-donor perature should proceed by displacement of the 1,5-cyclooc-
ligands with nine-carbon, branched alkyl substituents (Fig- tadiene ligand, followed by coordination of two P-donor
ure 1) and their application to the rhodium-catalysed hy- ligands. With tris(3,5,5-trimethylhexyl) phosphite (1) in a
droformylation of 1-octene in scCO2 and in toluene as sol- P/Rh molar ratio of 2:1, the complex [Rh(cod)(1)2]PF6 (4)
vents. Phosphite (1), phosphonite (2) and phosphinite (3) was obtained as a relatively air-stable, yellow oil in high
ligands were selected because the introduction of oxy yield. Several attempts to solidify the complex were unsuc-
groups has a positive effect on activity and regioselectivi- cessful. Its 31P{1H} NMR spectrum shows a doublet at δ
ty.[3b,11] Bulky monophosphonite ligands have shown very = 116.1 ppm (JP,Rh = 244.0 Hz), which corresponds to the
high activities in the isomerisation/hydroformylation of oc- coordinated phosphite ligand, and the characteristic sep-
–
tene.[11] We also studied the coordination of the new ligands tuplet of the PF6 counteranion at δ = –143.2 ppm (JP,F
=
to rhodium() and palladium().
711.5 Hz). The presence of coordinated cyclooctadiene was
confirmed by the H NMR spectrum, which shows signals
1
at δ = 4.05 ppm (HC=CH) and 2.57 and 2.36 ppm
(-CH2-). The 1H NMR signals corresponding to the coordi-
nated ligand are shifted slightly with respect to those of the
free ligand. The mass spectrum shows a signal at m/z =
1129.5 corresponding to the [Rh(cod)(1)2]+ fragment.
Figure 1. P-donor ligands.
Results and Discussion
Synthesis of Ligands
Ligands 1–3 were prepared from the commercially avail-
able alcohol 3,5,5-trimethylhexanol by reaction with phos-
phorus trichloride or the corresponding chlorophenylphos-
phane in diethyl ether in the presence of pyridine Scheme 2. Syntheses of 4–6.
(Scheme 1). The ligands were purified by flash chromatog-
raphy on basic alumina eluting with hexane under an inert
However, upon treatment of the same precursor complex
gas and obtained as air- and moisture-sensitive colourless [Rh(cod)2]PF6 with the same P/Rh molar ratio but using
oils in good yields (56–80%). The 1H NNMR spectra show phosphonite 2, the 31P{1H} NMR spectrum shows two
the methylene (-OCH2-) signals at δ = 3.8 ppm, the methyl- doublets in the region of coordinated phosphorus atoms at
ene and methine signals between δ = 1.6 and 1.0 ppm, and δ = 146.0 (JP,Rh = 165.9 Hz) and 138.5 (JP,Rh = 170.8 Hz)
the methyl doublet and singlet from the tert-butyl group at ppm and the 1H NMR spectrum shows signals correspond-
δ = 0.9 ppm. The signals were assigned by means of COSY ing to coordinated cyclooctadiene (at δ = 4.0 and 2.5–
and HETCOR experiments. The 31P{1H} NMR singlet sig- 2.7 ppm). When the P/Rh molar ratio is 4:1, the 31P{1H}
nals appear at δ = 139.9, 156.6 and 112.5 ppm for 1–3, NMR spectrum shows only the signal at δ = 146.0 ppm.
respectively, which are typical values for this kind of phos- There was no evidence of coordinated COD in the 1H
phorus compounds.[12]
NMR spectrum, and only signals attributable to the coordi-
nated ligand were detected. In this case, a relatively air-
stable, yellow, oily solid was obtained in 76% yield. The
mass spectrum of the isolated product has a signal m/z =
1679.7 corresponding to the cationic fragment [Rh(2)4]+.
We propose that, at a P/Rh ratio of 2:1, a mixture of
[Rh(cod)(2)2]PF6 and [Rh(2)4]PF6 (5) is formed and the tot-
ally substituted species 5 is formed at a P/Rh ratio of 4.
Similar [RhL4]+ species have been obtained with
PPh(OCH3)2,[13] with similar 31P NMR spectroscopic data
(δ = 148 ppm, JP,Rh = 170 Hz).[14]
Scheme 1. Synthesis of 1–3.
Synthesis of Complexes
In the reaction of [Rh(cod)2]PF6 with ligand 3 only one
To explore the coordination chemistry of the P-donor doublet is observed in the 31P{1H} NMR spectrum at P/Rh
ligands 1–3 we decided to study their reactivity with rhodi- ratios of 2:1 and 4:1 [δ = 132.3 ppm (JP,Rh = 162.2 Hz)],
um() and palladium() complexes. We chose [Rh(cod)2]PF6 which agrees with the data reported for [Rh{PPh2(OR)}4]+
(cod = 1,5-cyclooctadiene) as a model for cationic com- (R = Me: δ = 132.2 ppm, JP,Rh = 159 Hz; R = Et: δ =
plexes (Scheme 2). The reaction of ligands 1–3 with 130.5 ppm, JP,Rh = 156 Hz),[15] along with a septuplet signal
–
1
[Rh(cod)2]PF6 in anhydrous dichloromethane at room tem- for PF6 at δ = –143.1 ppm (JF,P = 712.6 Hz). In the H
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Rh-Catalysed Hydroformylation of 1-Octene
FULL PAPER
NMR spectrum there are only signals corresponding to the
coordinated ligand 3. A relatively air-stable, yellow solid
was isolated in 73% yield. The X-ray crystal structure (see
below) shows that this complex is [Rh(3)4]PF6 (6).
To prepare neutral palladium complexes, we chose
[PdCl2(PhCN)2] as a model precursor. The reaction of li-
gands 1–3 with [PdCl2(PhCN)2] in anhydrous dichloro-
methane at room temperature proceeds by the displacement
of two molecules of PhCN followed by the coordination of
two P ligands to afford [PdCl2(1–3)2] (7–9, Scheme 3),
which were obtained as relatively air-stable, yellow oils in
good yields, with mass spectra in agreement with a mono-
nuclear formulation. The 1H NMR spectra of 7–9 show sig-
nals corresponding to the coordinated ligands. The 31P{1H}
NMR spectra show only one singlet at δ = 94.2 (7), 122.2
(8) and 110.2 ppm (9), which indicates that only one of the
two possible isomers (cis or trans) is formed. The difference
between the 31P NMR signal of the complex and that of
the free ligand, known as the coordination chemical shift,
∆ (= δcoord – δfree), for similar palladium() complexes is
indicative of the stereochemistry of these complexes. The
lowest (negative) values of ∆ are found for cis isomers con-
taining ligands with Tolman angles, Θ, of less than 140°,
and high values (positive) of ∆ are found for trans isomers
containing ligands with Tolman angles higher than 140°.[16]
Based on this observation, since the values of ∆ for com-
plexes 7 and 8 are –45.7 and –34.4 ppm, respectively, we
propose that the cis isomers are present in these complexes.
In the case of complex 9 the value of ∆ is –2.3 ppm. Taking
into account that the estimated value of Θ from the X-ray
structure is 128° (see below), we also propose the formation
of the cis isomer for complex 9.
Figure 2. ORTEP drawing of complex 6. PF6– and hydrogen atoms
have been omitted for clarity.
Table 1. Selected bond lengths [Å] and angles [°] of complex 6.[a]
Rh1–P2
P2–C3
P2–C9
P2–O15
O15–C16
2.2848(6)
1.8222(25)
1.815(2)
1.6170(17)
1.447(3)
P2i–Rh1–P2iii
P2i–Rh1–P2ii
C3–P2–Rh1
C9–P2–Rh1
O15–P2–Rh1
C9–P2–C3
90.776(3)
166.64(3)
115.75(8)
118.97(8)
107.03(6)
105.14(11)
[a] Estimated standard deviations are given in parentheses. P2i,
P2iii: phosphorus atoms located in cis position; P2i, P2ii: phospho-
rus atoms located in trans position.
greater extent, has been reported for [Rh(PMe3)4]+ (trans P–
Rh–P angles of 148.29 and 151.46°).[18] The C–P–Rh angles
[115.75(8) and 118.97(8)°] deviate from the ideal tetrahedral
value, as observed in coordinated P-donor ligands. The esti-
mated Tolman angle for 3, calculated in accordance with
the reported method,[19] is 128°. The alkoxy chains are in a
staggered arrangement above and below the coordination
plane in order to minimise repulsion. There is a disorder in
Scheme 3. Syntheses of 7–9.
–
the tBu fragments. The PF6 anions are located in the cavi-
ties formed between the four tBu groups from two different
cationic units.
X-ray Structure of 6
The crystal structure of complex 6 was solved with crys-
tals obtained by slow diffusion of diethyl ether into a
dichloromethane solution of the complex. The X-ray struc-
ture is shown in Figure 2 and selected bond lengths and
angles are given in Table 1.
Reactivity of [Rh(acac)(CO)2]/1–3 with CO and H2
The reactivity of the systems [Rh(acac)(CO)2]/1–3 with
CO and H2 was analysed by high-pressure NMR
This cationic rhodium complex contains four coordi- (HPNMR) and IR (HPIR) spectroscopy. The 31P{1H} and
nated phosphinite ligands 3, as observed in solution. The 1H NMR spectra were recorded for the complex
Rh–P bond lengths [2.2848(6) Å] are in the range reported [Rh(acac)(CO)2] in the presence of 4 equiv. of ligand 1–3 in
for other RhI complexes with phosphinite ligands.[17] The [D6]toluene ([Rh] = 2×10–2 ) with stepwise addition of H2
cation has a slightly tetrahedrally distorted square-planar and CO. As the IR technique is more sensitive, the IR spec-
geometry [trans P–Rh–P angles of 166.64(3)°] due to intra- tra could be recorded at concentrations closer to the cata-
molecular ligand repulsion. A similar distortion, but to a lytic value (2–5×10–3 ) in methyltetrahydrofuran under
Eur. J. Inorg. Chem. 2006, 1067–1075
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M. Giménez-Pedrós, A. Aghmiz, N. Ruiz, A. M. Masdeu-Bultó
FULL PAPER
the same conditions. A list of identified species is given in JP,H = 3 Hz) ppm].[20] The minor signal at δ = 154.6 (JRh,P
Table 2.
= 194.6 Hz) ppm is attributed to the dicarbonyl species
[RhH(CO)2(1)2] (12), whose hydride signal is not detected
in the 1H NMR spectrum due to its low concentration. The
signals at δ = 140.8 and 70.2 ppm could correspond to
mixed complexes with phosphite/phosphonate and carbon
monoxide ligands formed by the partially decomposed li-
gand. Coordination of phosphonates to rhodium complexes
has been described in the literature[21] and the chemical
shifts observed here correlate with those reported for mixed
species. At the end of the experiment, the pressure was re-
leased and water was added to decompose the remaining
ligand. The signals at δ = 140.8 and 70.2 ppm disappeared
and new signals appeared, which could correspond to spe-
cies with only phosphonate ligands.
The HPIR spectra of [Rh(acac)(CO)2]/1 at 5 atm CO/H2
(1:1) in the ν(CO) region initially show signals at 2049,
2025, 2005, 1980 and 1960 cm–1. By comparison with pub-
lished data for [RhH(CO){P(OPh)3}3] [ν(CO) = 2060 (m)
cm–1],[22] the band at 2025 cm–1 was assigned to 11. The
absorptions at 2049 and 1980 cm–1 could correspond to the
equatorial/equatorial isomer ee-12 and those at 2005 and
1960 cm–1 could correspond to the equatorial/axial isomer
ea-12. The bands reported for ee-[RhH(CO)2{P(OPh)3}2]
appear at 2053 and 2018 cm–1 and for the isomer ea-
[RhH(CO)2{P(OPh)3}2] at 2034 and 1992 cm–1.[23] After 2 h
at 80 °C, bands appeared at 1991 and 1828 cm–1 attributed
Table 2. Identified species for [Rh(acac)(CO)2]/1–3 (P/Rh = 4) sys-
tems at 5 atm CO/H2 (1:1) after 1 h at 80 °C.
Complex
δ(31P)
[ppm]
(JRh,P
[Hz])
δ(1H) (hydride)
[ppm]
(JP,H, JRh,H [Hz])
ν(CO)
[cm–1]
[RhH(1)4] (10)
157.9 d
(207.8)
158.9 d
–11.8 dq
(33.7, 9.4)
–10.7 quint
–
[RhH(CO)(1)3]
(11)
2025
(212.3)
154.6 d
(7.8, 7.8)
n.d.[a]
[RhH(CO)2(1)2]
(12)
2049,
2005,
1980, 1960
2065
(194.6)
169.8 d
[RhH(CO)(2)3]
(13)
–10.0 quint
(189.0)
168.2 d
(7.7, 7.7)
n.d.[a]
[RhH(CO)2(2)2]
(14)
2073,
2042,
2029, 1991
2025
(145.7)
138.1 d
[RhH(CO)(3)3]
(15)
–9.4 dq
(163.3)
136.8 d
(12.3, 4.7)
–9.1 dt
[RhH(CO)2(3)2]
(16)
2044,
2006,
1996, 1918
(147.2)
(11.7, 6.3)
[a] n.d. = not detected.
Upon addition of 4 mol-equiv. of 1 to [Rh(acac)(CO)2] to rhodium species with bridging carbonyl ligands.
in toluene, the 31P{1H} spectrum shows a major, broad The 31P{1H} and 1H NMR spectra of the [Rh(acac)-
doublet signal at δ = 140 ppm, attributed to a mixture of (CO)2]/2 system (P/Rh = 4) in toluene under 5 atm of CO/H2
the species [Rh(acac)(CO)n(1)2–n], along with a small mul- (1:1), after heating at 80 °C for 1 h, show signals assigned
tiplet at δ = 80 ppm and a singlet at δ = 0 ppm due to to [RhH(CO)(2)3] (13) and [RhH(CO)2(2)2] (14; Table 2);
1
decomposed ligand. Addition of 2.5 atm of H2 to this solu- the hydride signals could not be detected in the H NMR
tion caused two new doublet signals to appear in the spectrum. The signal of the remaining unreacted species
31P{1H} NMR spectrum at δ = 158.9 ppm (J = 212.3 Hz) [Rh(acac)(CO)n(2)2–n] appears at δ = 156 ppm. The slow re-
and δ = 157.9 ppm (J = 207.8 Hz). Two new signals also action rate of similar precursors containing phosphite li-
1
appear in the hydride region of the H NMR spectrum at δ gands with CO/H2 has been reported.[24] The broad doublet
= –10.7 ppm (quint, J = 7.8 Hz) and δ = –11.8 ppm (dq, J at δ = 144.1 (JRh,P = 168.7 Hz) ppm is better resolved at
= 33.7, 9.4 Hz). After further addition of 2.5 atm of CO –60 °C and could correspond to dimeric Rh0 complexes
(5 atm total pressure) and heating of the system at 80 °C [Rh2(CO)6(2)2] or [Rh2(CO)4(2)4], as has been observed for
for 1 h, the doublet signal in the 31P{1H} NMR spectrum other P-donor–rhodium systems.[25] The broad multiplets at
at δ = 157.9 ppm, the multiplet signal at δ = 80 ppm and the δ = 120 and 82 ppm were attributed to mixed phosphonite/
1
hydride signal at δ = –11.8 ppm in the H NMR spectrum phosphonate species.
disappear and new signals are observed at δ =154.6 (d, JRh,P
The HPIR spectrum, after 1 h under these reaction con-
= 194.6 Hz), 140.8 (dd, J = 273.6, 164.7 Hz), 138.1 (s, free ditions, shows several absorptions in the 2200–1800 cm–1
1) and 70.2 (dt, J = 273.4, 94.3 Hz) ppm. We assigned the region that were difficult to assign. The band at 2065 could
signals at δ = 157.9 ppm and the hydride doublet of quintu- correspond to compound 13 and the ones at 2073 and
plets at δ = –11.8 ppm to the species [RhH(1)4] (10) by com- 2029 cm–1 and 2042 and 1991 cm–1 could correspond to the
parison with published data for the analogous species ee and ea isomers of 14, respectively. The absorptions
[RhH{P(OPh)3}4] [δP = 129.7 (JRh,P = 232.8 Hz) ppm; around 1800 cm–1 could correspond to the Rh0 dimeric spe-
δH(hydride) = –10.6 (JRh,H = 44, JP,H = 7 Hz) ppm].[20] We cies.
assigned the major doublet signal at δ = 158.9 ppm in the
The 31P{1H} NMR spectrum of [Rh(acac)(CO)2]/3
31P{1H} NMR spectrum together with the quintuplet at δ (P/Rh = 4) at 5 atm CO/H2 (1:1), after 1 h at 80 °C, shows
1
= –10.7 ppm in the H NMR spectrum to [RhH(CO)(1)3] a major signal at δ = 138.1 ppm, which, together with a
(11). The multiplicity of the hydride signal (quintuplet) is hydride signal at δ = –9.4 ppm, was attributed to the species
1
explained by the accidentally identical values of JRh,H and [RhH(CO)(3)3] (15) by comparison with published data.[26]
2JP,H, as was also reported for [RhH(CO){P(OPh)3}3] [δP = A minor, partially overlapped doublet at δ = 136.8 ppm,
141.1 (JRh,P = 240 Hz) ppm; δH(hydride) = –10.9 (JRh,H
=
together with a hydride doublet of triplets at δ = –9.1 ppm,
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Rh-Catalysed Hydroformylation of 1-Octene
FULL PAPER
was attributed to the species [RhH(CO)2(3)2] (16). In com-
parison, [RhH(CO){PPh2(OPh)}3] shows signals at δP
=
142 (JP,Rh = 169 Hz) ppm and δH = –9.4 (dq, JH,P = 13,
JH,Rh = 3 Hz) ppm and [RhH(CO)2{PPh2(OPh)}2] shows
signals at δP = 145 (JP,Rh = 165 Hz) ppm and δH
=
Scheme 4. Hydroformylation of 1-octene using different
[Rh(acac)(CO)2]/1–3 systems.
–9.5 ppm.[27] The signals at δ = 130.8 and 84.9 ppm in the
31P{1H} spectrum may correspond to mixed phosphinite/
phosphonate species, as proposed for the other systems.
The IR spectrum of [Rh(acac)(CO)2]/3, under the same Hydroformylation of 1-Octene in Toluene
conditions, initially shows only one band at 1987 cm–1 in
Table 3 (Entries 1–7) shows the results of 1-octene hydro-
the 2200–1800 cm–1 region. After 1 h of stirring at 80 °C,
five absorptions are present at 2044, 2025, 2006, 1966 and
1918 cm–1. The band at 2025 cm–1 was assigned to 15, the
absorptions at 2044 and 1966 cm–1 were attributed to iso-
mer ee-16, since they are similar to ones reported for the
equatorial/equatorial isomer of [RhH(CO)2{PPh2(OPh)}2]
(2045, 1970 cm–1),[27] the ones at 2006 and 1918 cm–1 could
correspond to the isomer ea-16.
formylation in toluene using [Rh(acac)(CO)2]/1–3 as the
catalyst precursor. The products obtained were the isomeric
aldehydes n-nonanal (18) and isononanal (19) and the isom-
erised products 2-octene [(E) and (Z)], (3E)-3-octene and
(4E)-4-octene. No hydrogenated products were observed.
The selectivity towards isomerised products is also listed.
Hydroformylation with [Rh(acac)(CO)2]/1 in toluene
(Entry 1, Table 3) shows high activity (conversion = 98%)
with a high selectivity for aldehydes at a P/Rh molar ratio
of 4, although isomerised octenes were also formed. The
n/iso ratio is relatively high (3.5), as is observed for other
rhodium/phosphite systems.[3b] When the P/Rh ratio was re-
duced to 2, the conversion, and especially the selectivity,
decreased (Entry 2, Table 3).
In summary, the study of the reactivity of [Rh(acac)-
(CO)2]/1–3 with CO and H2 at 5 atm (CO/H2 = 1:1) and
80 °C has shown that the precursors [RhH(CO)(1–3)3] are
formed as the main species in all cases.
The catalyst precursors with ligands 2 and 3 provided
very low selectivity for the aldehydes and produced octene
isomers as the main products (Entries 3–7, Table 3). Since
Hydroformylation of 1-Octene
We studied the hydroformylation of 1-octene (17) to ob- these poor donor ligands tend to form rhodium species with
tain the corresponding linear (18) and branched (19) alde- a high number of coordinated ligands per rhodium atom
hydes (Scheme 4) in toluene as a model solvent and in (see synthesis section above), which can inhibit hydrofor-
scCO2.
mylation,[28] we performed an experiment with a lower
Table 3. Hydroformylation of 1-octene using [Rh(acac)(CO)2]/1–3 catalyst precursors in scCO2.[a]
Conv.[c]
[%]
Sa
18/19
[%]
Si[e]
[%]
[b]
[d]
Entry
L
Solvent
L/Rh
T
[°C]
P(H2)
[atm]
P(CO)
[atm]
Ptot
[atm]
[%]
1
2
1
1
2
2
3
3
3
1
1
1
1
1
1
2
2
2
3
3
3
toluene
toluene
toluene
toluene
toluene
toluene
toluene
–
scCO2
scCO2
scCO2
scCO2
scCO2
scCO2
scCO2
scCO2
scCO2
scCO2
scCO2
4
2
4
4
4
2
4
4
4
6
6
6
6
4
4
6
4
2
6
80
80
80
80
80
80
80
80
80
80
80
100
100
80
80
100
80
80
100
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
10
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
10
5
5
5
5
5
5
5
5
167
167
167
167
250
167
167
250
167
167
250
98
85
89
95
95
95
98
88
57
20
6
49
82
40
15
70
13
35
24
86
24
21
47
38
6
36
80
25
68
86
90
89
76
12
94
41
9
78:22
74:26
77:23
53:47
71:29
57:37[h]
63:27
74:24[h]
81:19
85:15
81:19
80:20
78:22
76:24
45:55
77:23
85:15
77:23
75:25
10
75
79
53
58
93
64
20
74
30
14
10
11
24
79
6
3
4[f]
5
6
7[f]
8
9
10
11
12
13
14
15[g]
16
17
18
19
10
10
10
10
2.5
2.5
10
2.5
2.5
10
2.5
2.5
10
2.5
2.5
10
59
91
19
79
[a] Reaction conditions: toluene: [Rh(acac)(CO)2] = 0.024 mmol, alkene = 4.8 mmol, alkene/Rh = 200, V = 10 mL, t = 3 h; scCO2:
[Rh(acac)(CO)2] = 0.06 mmol, alkene = 12 mmol, alkene/Rh = 200, V = 25 mL, t = 3 h. [b] Total pressure. [c] Total conversion measured
by GC. [d] Selectivity for aldehydes. [e] Selectivity for isomerized products (internal octenes). [f] Preactivated system at 5 atm (CO/H2 =
1), T = 80 °C for 1 h. [g] Preactivated system at 5 atm (CO/H2 = 1), T = 80 °C for 1 h in diethyl ether. [h] 2-Ethylheptanal was also
detected.
Eur. J. Inorg. Chem. 2006, 1067–1075
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1071

M. Giménez-Pedrós, A. Aghmiz, N. Ruiz, A. M. Masdeu-Bultó
FULL PAPER
P/Rh ratio (Entry 6, Table 3); the selectivity for aldehydes Table 3). To favour the formation of the active species in
decreased dramatically. one of the experiments (Entry 15, Table 3), the system was
The low selectivity for aldehydes has been attributed to preactivated in diethyl ether at 5 atm (CO/H2 = 1) at 80 °C
the nonformation of the active species [RhH(CO)(L)3]. Our for 1 h. The solvent was then evaporated and 1-octene was
HPIR experiments showed that, in the case of systems with added. The system was pressurised and heated again to
2 and 3, an activation time is needed before these species 80 °C and the reaction started. In this case the conversion
are detected. The system [Rh(acac)(CO)2]/2 was therefore and selectivity decreased considerably and decomposition
preactivated in toluene at 5 atm (CO/H2 = 1) and 80 °C for of the catalyst was observed at the end of the reaction. Un-
1 h. 1-Octene was then added, the system was pressurised der the optimised conditions, we obtained high selectivity
and again heated to 80 °C, and the reaction started. The for aldehydes (94%) and a conversion of 70%.
conversion was slightly higher and the selectivity for alde-
When the system [Rh(acac)(CO)2]/3 (Entries 17–19,
hydes increased from 21 to 47% (Entry 4, Table 3). Similar Table 3) was used, the best results were also obtained under
results were obtained when the preactivated catalyst precur- the optimised conditions (selectivity for aldehydes 79% and
sor with ligand 3 was used (Entry 7, Table 3).
conversion of 24%).
Rhodium catalysts with phosphonite ligands have been
In summary, the catalyst precursors formed with
shown to have very high activity in the isomerisation/hydro- [Rh(acac)(CO)2]/1–3 are active in the hydroformylation of
formylation of internal alkenes.[11] When we used 1-octene in scCO2. In the catalyst system with the phosphite
[Rh(acac)(CO)2]/2 under the same conditions as for the hy- 1, similar conversion and selectivities to those of the toluene
droformylation of (2E)-2-hexene, 17% total conversion was reaction can be achieved by optimising the reaction condi-
obtained with a selectivity of 45% for aldehydes and a 1- tions. The selectivity for aldehyde of the rhodium catalyst
heptanal/2-methylhexanal/3-ethylpentanal ratio of 24:54:22, precursors with ligands 2 and 3 increases, especially with
which indicates that the isomerisation rate is slower than ligand 2, when scCO2 is used as the reaction medium in-
the hydroformylation rate for these systems.
stead of toluene.
Hydroformylation of 1-Octene in Supercritical CO2
The solubility of the catalyst precursors in scCO2 was
studied using a Thar autoclave equipped with sapphire win-
dows. The purged autoclave was charged with
[Rh(acac)(CO)2]/1–3 (P/Rh = 4), filled with CO/H2 at 5 atm
(CO/H2 = 1:1) and pressurised with CO2 up to 240 atm at
80 °C. Visual inspection through the windows showed that
the supercritical phase is colourless, which indicates that
there is no apparent solubility of these systems.
The catalytic experiments using scCO2 with systems
[Rh(acac)(CO)2]/1–3 are summarised in Table 3 (Entries 9–
19). A reference experiment with the system [Rh(acac)-
(CO)2]/1 without solvent provided lower conversion and se-
lectivity than when toluene was used as a solvent (Entry 8,
Table 3).
Conclusions
We have synthesised new P-donor ligands 1–3 with
branched substituents and studied their coordination to
RhI and PdII. We have characterised complexes [Rh(cod)-
(1)2]PF6, [Rh(2,3)4]PF6 and [PdCl2(1–3)2]. We have deter-
mined the X-ray structure of [Rh(3)4]PF6 and confirmed
the formation of the tetrakis(phosphite) complex. The reac-
tivity of [Rh(acac)(CO)2]/1–3 with CO/H2 at 5 atm (CO/H2
= 1) and 80 °C indicates that [RhH(CO)(1–3)3] is the main
species formed in solution. The solubility of the catalyst
precursors [Rh(acac)(CO)2]/1–3 in scCO2 is low but they
are active in the hydroformylation of 1-octene in scCO2. In
this solvent, the catalyst precursor with ligand 1 gives sim-
ilar activities and selectivities to those in toluene. Catalyst
precursors with ligands 2 and 3 give lower conversions than
in toluene but the aldehyde selectivity is higher.
As expected due to the low solubility of the catalyst pre-
cursors, the conversions with scCO2 were lower than for the
toluene systems under similar conditions. However, conver-
sion was good with the catalyst system [Rh(acac)(CO)2]/1
(Entry 9, Table 3), although the selectivity for aldehydes fell
to 25%. This led the linear/branched ratio to increase to
4.2. We optimised the conditions with this system by mod-
ifying the P/Rh ratio (Entry 10, Table 3), partial CO/H2
Experimental Section
General: All reactions were carried out under nitrogen using stan-
dard Schlenk techniques. Solvents were distilled and degassed prior
pressure (Entry 11, Table 3), temperature (Entry 12, to use. 1H, 13C{1H}, 19F and 31P{1H} NMR spectra were recorded
with Varian Gemini spectrometers operating at 300 or 400 MHz
(1H), 75.43 or 100.57 MHz (13C), 376.3 MHz (19F) or 121.44 or
161.92 MHz (31P). Chemical shifts are reported relative to tet-
ramethylsilane for 1H and 13C{1H} as internal reference, 85%
H3PO4 for 31P{1H} and CFCl3 for 19F. Mass spectrometry was per-
formed with either an AUTOSPEC (EI-HR) or an AUTOFLEX
spectrometer (MALDI-TOF). High-pressure NMR experiments
(HPNMR) were carried out in a 10-mm-diameter sapphire tube
with a titanium cap equipped with a Teflon/polycarbonate protec-
tion.[29] High-pressure IR experiments were performed in situ with
Table 3) and total pressure (Entry 13, Table 3). Under the
best conditions (P/Rh = 6, CO/H2 = 20 atm, T = 100 °C,
total pressure 250 atm), we achieved high conversion (82%)
and high selectivity for aldehydes (89%; Entry 13, Table 3)
probably because of the greater solubility of this system in
scCO2. Under these conditions, the linear/branched ratio
was similar to that of the toluene system.
When the system [Rh(acac)(CO)2]/2 was used in scCO2,
the selectivity for aldehydes increased from 47% to 76%,
although the conversion was lower (Entry 14 vs. Entry 4, an infrared autoclave.[30] Gas chromatography analyses were per-
1072
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Eur. J. Inorg. Chem. 2006, 1067–1075

Rh-Catalysed Hydroformylation of 1-Octene
FULL PAPER
formed with a Hewlett–Packard 5890A apparatus in an HP-5 (5%
diphenylsilicone/95% dimethylsilicone) column (25 m×0.2 mm) for
the separation of the products.
3JH,H = 6.0 Hz, 3 H, CH(CH3)CHH], 0.86 [d, 3JH,H = 6.4 Hz, 9 H,
CH(CH3)], 0.82 [s, 27 H, C(CH3)3] ppm. 13C NMR (100.5 MHz,
2
CDCl3, 20 °C): δ = 60.49 (d, JP,C = 10.6 Hz, POCH2), 51.21 [s,
3
CH(CH3)CH2], 40.52 (d, JP,C = 4.6 Hz, POCH2CH2), 31.11 [s,
Catalysis: Hydroformylation experiments were carried out in a Parr
autoclave (25 mL) with magnetic stirring. The autoclave was
equipped with a liquid inlet, a gas inlet, a CO2 inlet and a thermo-
couple. An electric heating mantle kept the temperature constant.
C(CH3)3], 29.99 [s, C(CH3)3], 25.91 [s, CH(CH3)], 22.53 [s,
CH(CH3)] ppm. 31P{1H} NMR (161.9 MHz, CDCl3, 20 °C): δ =
139.9 ppm. EIMS: m/z = 461 [M + H]+. High-resolution EIMS:
461.4120 (C27H58O3P).
Standard Hydroformylation Experiment in Toluene: The reactions in
toluene were carried out in the same Parr autoclave. The complex
[Rh(acac)(CO)2] (0.024 mmol) and the ligand (0.096 mmol) in tolu-
ene (10 mL) were stirred at room temperature for 1 h. The substrate
(4.8 mmol) was then added and the resulting solution was intro-
duced into the evacuated autoclave. The system was pressurised
and heated. When thermal equilibrium was reached, more gas mix-
ture was introduced until the desired pressure was attained. After
the required reaction time, the autoclave was cooled to room tem-
perature and depressurised. The products were identified by GC/
MS.
Preparation of Bis(3,5,5-trimethylhexyl) Phenylphosphonite (2): A
solution of dichloro(phenyl)phosphane (1.79 g, 0.010 mol) in
6.5 mL of diethyl ether was added dropwise to a solution of 3,5,5-
trimethylhexanol (2.88 g, 0.02 mol) and pyridine (1.58 g, 0.02 mol)
in 12 mL of diethyl ether at –10 °C. The solution was stirred at
room temperature for 7 h and then filtered. After all the solvent
had been removed under reduced pressure, the resulting colourless
oil was purified by flash chromatography on basic alumina eluting
with hexane. Yield: 2.21 g (56%) (colourless oil). 1H NMR
(400 MHz, CDCl3, 20 °C): δ = 7.59 (m, 2 H, Ph), 7.38 (m, 3 H,
Ph), 3.87 (m, 2 H, POCHH), 3.75 (m, 2 H, POCHH), 1.64 (m, 4
H, POCH2CHH + CHCH3), 1.43 (m, 2 H, POCH2CHH), 1.19 [m,
2 H, CH(CH3)CHH], 1.05 [m, 2 H, CH(CH3)CHH], 0.91 [d, 3JH,H
= 8.4 Hz, 6 H, CH(CH3)], 0.87 [s, 18 H, C(CH3)3] ppm. 13C NMR
(100.5 MHz, CDCl3, 20 °C): δ = 141.25 (d, 1JP,C = 19.2 Hz, Ci Ph),
129.84 (s, Cp Ph), 129.65 (d, 3JP,C = 2.3 Hz, Cm Ph), 128.08 (d, 2JC,P
Standard Hydroformylation Experiment in scCO2: The complex
[Rh(acac)(CO)2] (0.06 mmol) and the ligand (0.24 mmol) in diethyl
ether (2 mL) were stirred at room temperature for 30 min. The re-
sulting solution was introduced into the evacuated autoclave, and
the solvent was removed in vacuo. 1-Octene (12 mmol) was then
added. The system was pressurised with 5 atm of CO/H2 (1:1), and
liquid CO2 was introduced until a total pressure of 60 bar was
reached. The autoclave was heated to the desired temperature.
When thermal equilibrium was reached, the total pressure was ad-
justed with a Thar syringe pump. After the reaction time, the auto-
clave was cooled down to –10 °C and depressurised. The final mix-
ture was analysed by GC. The products were identified by GC/MS.
2
2
= 4.5 Hz, Co Ph), 65.04 (d, JP,C = 9.2 Hz, POCH2), 64.99 (d, JP,C
= 8.4 Hz, POCH2), 51.26 [s, CH(CH3)CH2], 51.22 [s, CH(CH3)
3
3
CH2], 40.77 (d, JC,P = 4.6 Hz, POCH2CH2), 40.72 (d, JC,P
=
4.3 Hz, POCH2CH2), 31.1 [s, C(CH3)3], 29.97 [s, C(CH3)3], 25.92
[s, CH(CH3)], 22.54 [s, CH(CH3)], 22.48 [s, CH(CH3)] ppm.
31P{1H} NMR (161.9 MHz, CDCl3, 20 °C): δ = 156.6 ppm. EIMS:
m/z = 394.3 [M]+. High-resolution EIMS: 394.2991 (C24H43O2P).
Solubility Studies: The solubility studies were carried out in a Thar
reactor (100 mL) equipped with sapphire windows and magnetic
stirring. The autoclave was charged with a solution of the ligand
(0.220 mmol) and [Rh(acac)(CO)2] (0.055 mmol) in diethyl ether.
The solvent was removed in vacuo, the reactor was pressurised with
syn-gas and CO2, the system was heated to 80 °C, and the total
pressure was adjusted to 240 atm. Solubility was monitored by vis-
ual inspection through the sapphire windows with a mirror due to
safety requirements.
Synthesis of 3,5,5-Trimethylhexyl Diphenylphosphinite (3): A solu-
tion of chlorodiphenylphosphane (1.00 g, 4.6 mmol) in 6.5 mL of
diethyl ether was added dropwise to a solution of 3,5,5-trimeth-
ylhexanol (0.66 g, 4.6 mmol) and pyridine (0.36 g, 4.6 mmol) in
12 mL of diethyl ether at –10 °C. The solution was stirred at room
temperature for 2 h and then filtered. After all the solvent had been
removed under reduced pressure, the resulting colourless oil was
purified by chromatography on basic alumina eluting with hexane.
Yield: 1.01 g (67%) (colourless oil). 1H NMR (400 MHz, CDCl3,
20 °C): δ = 7.40 (m, 4 H, Ph), 7.22 (m, 6 H, Ph), 3.78, (m, 2 H,
POCH2), 1.64 (m, 1 H, POCH2CHH), 1.55 [m, 1 H, CH(CH3)],
HPNMR: In a typical experiment, the NMR tube was filled under
N2 with a solution of [Rh(acac)(CO)2] (0.04 mmol), the ligand 1–3
(0.16 mmol) and [D8]toluene (2 mL). The tube was pressurised to
5 atm of CO/H2 (1:1) and left at 80 °C for 1 h. The NMR spectra
were then recorded.
2
3
1.40 (m, 1 H, POCH2CHH), 1.13 [dd, JH,H = 13.8 Hz, JH,H
=
=
2
3
3.8 Hz, 1 H, CH(CH3)CHH], 0.96 [dd, JH,H = 14.2 Hz, JH,H
3
6.8 Hz, 1 H, CH(CH3)CHH], 0.82 [d, JH,H = 6.2 Hz, 3 H,
CH(CH3)], 0.77 [s, 9 H, C(CH3)3] ppm. 13C NMR (100.5 MHz,
HPIR: In a typical experiment, the HPIR cell was filled under N2
with a solution of [Rh(acac)(CO)2] (0.036 mmol), the ligand 1–3
(0.144 mmol) and methyltetrahydrofuran (15 mL). The cell was
pressurised to 5 atm of CO/H2 (1:1) and left at 80 °C for 1 h. The
IR spectra were then recorded.
2
CDCl3, 20 °C): δ = 142.28 (d, JP,C = 18.8 Hz, Ci Ph), 130.54 (d,
2
2JP,C = 7.6 Hz, Co Ph), 130.33 (d, JP,C = 7.6 Hz, Co Ph), 129.12
3
(d, JP,C = 5.3 Hz, Cm Ph), 128.26 (s, Cp Ph), 128.19 (s, Cp Ph),
2
68.50 (d, JP,C = 19,1 Hz, POCH2), 51.21 [s, CH(CH3)CH2], 40.83
3
(d, JP,C = 7.6 Hz, POCH2CH2) 31.08 [s, C(CH3)3], 29.99 [s,
Preparation of Tris(3,5,5-trimethylhexyl) Phosphite (1): A solution
of phosphorus trichloride (0.87 g, 6.3 mmol) in 6.5 mL of diethyl
ether was added dropwise to a solution of 3,5,5-trimethylhexanol
(2.74 g, 0.019 mol) and pyridine (1.50 g, 0.019 mol) in 12 mL of
diethyl ether at –10 °C. The solution was stirred at room tempera-
ture for 2 h. The solution was filtered and the solvent was removed.
The resulting colourless oil was purified by flash chromatography
C(CH3)3] 29.95 [s, C(CH3)3], 25.92 [s, CH(CH3)], 22.50 [s,
CH(CH3)] ppm. 31P{1H} NMR (161.9 MHz, CDCl3, 20 °C): δ =
112.5 ppm. EIMS: m/z = 328.2 [M]+. High-resolution EIMS:
328.1961 (C21H29OP).
Preparation of [Rh(C8H12)(1)2]PF6 (4): Ligand
1 (221 mg,
0.48 mmol) was added to a solution of [Rh(cod)2]PF6 (93 mg,
0.20 mmol) in 2 mL of anhydrous dichloromethane. The solution
turned yellow immediately and was stirred for 1 h. The solvent was
on basic alumina eluting with hexane. Yield: 2.33 g (80%) (colour-
1
less oil). H NMR (400 MHz, CDCl3, 20 °C): δ = 3.74 (q, JH,P
=
JH,H = 7.1 Hz, 6 H, POCH2), 1.57 (m, 6 H, POCH2CHH + then evaporated in vacuo and the product washed with cold meth-
2
CHCH3) 1.36 (m, 3 H, POCH2CHH), 1.15 [dd, JH,H = 14.0 Hz,
anol. The product was obtained as a yellow oil. Yield: 219 mg
2
3JH,H = 3.4 Hz, 3 H, CH(CH3)CHH], 1.00 [dd, JH,H = 14.0 Hz, (86%). 1H NMR (400 MHz, CDCl3, 20 °C): δ = 4.05 (m, 16 H,
Eur. J. Inorg. Chem. 2006, 1067–1075
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1073

M. Giménez-Pedrós, A. Aghmiz, N. Ruiz, A. M. Masdeu-Bultó
FULL PAPER
POCH2 + CH= cod), 2.57 (m, 4 H, CH2 cod), 2.36 (m, 4 H, CH2
CH(CH3)] 22.67 [s, CH(CH3)] ppm. 31P{1H} NMR (161.9 MHz,
CDCl3, 20 °C): δ = 94.2 (s) ppm. MS (MALDI-TOF): m/z = 1063.7
[M – Cl]+, 1026.7 [M – 2 Cl]+.
2
cod), 1.60 (m, 18 H, POCH2CH2 + CHCH3), 1.22 [dd, JH,H
=
=
=
3
2
14.0 Hz, JH,H = 3.6 Hz, 6 H, CH(CH3)CHH], 1.14 [dd, JH,H
3
3
14.0 Hz, JH,H = 6.0 Hz, 6 H, CH(CH3)CHH], 0.97 [d, JH,H
Preparation of [PdCl2(2)2] (8): Ligand 2 (51 mg, 0.12 mmol) was
added to a solution of [PdCl2(PhCN)2] (25 mg, 0.06 mmol) in 2 mL
of anhydrous dichloromethane. The solution was stirred for 1 h,
then the solvent was evaporated in vacuo and the product was
washed with cold methanol and dried under vacuum overnight.
6.4 Hz, 18 H, CH(CH3)], 0.90 [s, 54 H, C(CH3)3] ppm. 13C NMR
(100.5 MHz, CDCl3, 20 °C): δ = 106.2 (m, CH= cod), 65.2 (d, JC,P
= 6.1 Hz, POCH2), 51.3 [s, CH(CH3)CH2], 39.8 (d, POCH2CH2),
31.1 [s, C(CH3)3], 29.9 [s, C(CH3)3] 26.1 [s, CH(CH3)], 22.5 [s,
CH(CH3)] ppm. 19F NMR (376.3 MHz, CDCl3, 20 °C): δ = –73.11
(d, JP,F = 715.4 Hz) ppm. 31P{1H} NMR (161.9 MHz, CDCl3,
1
The product was obtained as a yellow oil. Yield: 47 mg (81%). H
NMR (400 MHz, CDCl3, 20 °C): δ = 7.75 (m, 4 H, Ph), 7.45 (m,
6 H, Ph), 4.20 (br. m, 4 H, POCHH), 3.95 (br. m, 4 H, POCHH),
1.71 (br. m, 4 H, POCH2CHH), 1.54 (br. m, 8 H, POCH2CHH +
CHCH3), 1.13 [br. m, 8 H, CH(CH3)CH2], 0.90 [d, 3JH,H = 6.4 Hz,
12 H, CH(CH3)] 0.87 [s, 36 H, C(CH3)3] ppm. 13C NMR
(100.5 MHz, CDCl3, 20 °C): δ = 140.70 (br., Ci Ph), 132.55 (s, Co
Ph), 131.74 (s, Cm Ph), 129.07, (s, Cp Ph), 67.83 (s, POCH2), 50.93
[s, CH(CH3)CH2], 39.22 (s, POCH2CH2), 30.88 [s, C(CH3)3], 29.77
[s, C(CH3)3], 25.82 [s, CH(CH3)], 22.26 [s, CH(CH3)] ppm. 31P{1H}
NMR (161.9 MHz, CDCl3, 20 °C): δ = 122.2 (s) ppm. MS
(MALDI-TOF): m/z = 929.4 [M – Cl]+, 894.4 [M – 2 Cl]+.
20 °C): δ = 116.1 (d, JRh,P = 244.0 Hz), –143.2 [sept, JF,P
=
711.5 Hz] ppm. MS (MALDI-TOF): m/z = 1129.54 [M – PF6 – 3
H]+, 1003.45 [M – PF6 – C9H20 – H]+.
Preparation of [Rh(2)4]PF6 (5): Ligand 2 (316 mg, 0.80 mmol) was
added to a solution of [Rh(cod)2]PF6 (46.5 mg, 0.20 mmol) in 2 mL
of anhydrous dichloromethane. The solution turned yellow imme-
diately and was stirred for 1 h. The solvent was evaporated and the
residue washed with cold methanol and dried in vacuo overnight
to give the product as a yellow oily solid. Yield: 277 mg (76%). 1H
NMR (400 MHz, CDCl3, 20 °C): δ = 7.5 (m, 20 H, Ph), 3.47 (br.
m, 8 H, POCHH), 3.16 (br., 8 H, POCHH), 1.38 (br. m, 24 H,
POCH2CH2 + CHCH3), 1.02 [br. m, 16 H, CH(CH3)CH2], 0.85 [d,
Preparation of [PdCl2(3)2] (9): Ligand 3 (85.63 mg, 0.26 mmol) was
added to a solution of [PdCl2(PhCN)2] (50 mg, 0.13 mmol) in 2 mL
of anhydrous dichloromethane. The solution was stirred for 1 h,
the solvent was evaporated in vacuo and the residue was washed
with methanol. The product was obtained as a yellow oil. Yield:
3JH,H = 5.6 Hz, 24 H, CH(CH3)], 0.87 [s, 72 H, C(CH3)3] ppm. 13
C
NMR (100.5 MHz, CDCl3, 20 °C): δ = 137.74 (br., Ci Ph), 131.47
(s, Co Ph), 130.33 (s, Cm Ph) 128.34 (s, Cp Ph), 66.00 (br., POCH2)
51.19 [s, CH(CH3)CH2], 39.91 (s, POCH2CH2), 31.01 [s, C(CH3)3],
29.90 [s, C(CH3)3], 26.21 [s, CH(CH3)], 22.65 [s, CH(CH3)] ppm.
1
98 mg (91%). H NMR (400 MHz, CDCl3, 20 °C): δ = 7.81 (m, 8
H, Ph), 7.46 (m, 12 H, Ph), 3.63 (m, 4 H, POCH2), 1.31–1.19 [m,
19F NMR (376.3 MHz, CDCl3, 20 °C): δ = –74.32 (d, JF,P
=
3
6 H, POCH2CH2 + CH(CH3) + CH(CH3)CH2], 0.92 [d, JH,H
=
710.8 Hz) ppm. 31P{1H} NMR (161.9 MHz, CDCl3, 20 °C): δ =
146.0 (d, JP,Rh = 169.7 Hz), –143.2 (sept, JP,F = 711.5 Hz) ppm. MS
(MALDI-TOF): m/z = 1679.7 [M – PF6 – 2 H]+ 1285.56 [M –
PF6 – 4 H]+.
4.4 Hz, 6 H, CH(CH3)], 0.78 [s, C(CH3)3] ppm. 13C NMR
(100.5 MHz, CDCl3, 20 °C): δ = 140.4 (br. Ci Ph), 132.58 (d, JP,C
2
= 6.1 Hz, Co Ph), 132.52 (d, 2JP,C = 6.1 Hz, Co Ph), 131.75 (br., Cm
Ph), 128.20 (br., Cp Ph), 67.86 (s, POCH2), 50.93 [s, CH(CH3)CH2],
39.22 (POCH2CH2), 30.87 [s, C(CH3)3], 29.76 [s, C(CH3)3], 25.81
[s, CH(CH3)], 22.26 [s, CH(CH3)] ppm. 31P NMR (161.9 MHz,
CDCl3, 20 °C): δ = 110.21 (s) ppm. MS (MALDI-TOF): m/z =
796.9 [M – Cl]+, 762.0 [M – 2 Cl]+.
Preparation of [Rh(3)4]PF6 (6): Ligand 3 (158 mg, 0.47 mmol) was
added to a solution of [Rh(cod)2]PF6 (80 mg, 0.20 mmol) in 2 mL
of anhydrous dichloromethane. The solution turned yellow imme-
diately and was stirred for 1 h. Diethyl ether was then added to the
solution to afford a yellow solid. Yield: 228 mg (73%). 1H NMR
(400 MHz, CDCl3, 20 °C): δ = 7.2–7.3 (m, 40 H, Ph), 2.78 (br. m,
8 H, POCH2), 0.80 [m, 12 H, POCH2CH2CH(CH3)], 0.67 [dd,
Crystal Data for Complex 6: Suitable crystals of complex 6 were
grown by slow diffusion of diethyl ether into a solution of the com-
plex in dichloromethane and mounted on a glass fibre. The mea-
surements were taken at 120 K with a Bruker SMART CCD1000
diffractometer equipped with a graphite-monochromated Mo-Kα
radiation source (λ = 0.71073 Å). Data collection and processing
were carried out with Smart and Saint from Bruker. Complex 6
(C84H112O4P4Rh·PF6) crystallised in a tetragonal P4/n space group
with a = 18.021 (2), c = 13.431 (3) Å, V = 4361.8 (12) Å3, M =
1557.50, Z = 2, ρcalcd. = 1.186 mgm–3, µ = 0.345 mm–1. The yellow
crystal was prismatic and of dimensions 0.6×0.52×0.48 mm. The
θ range for measurement was 1.52–26.37° and 4471 unique reflec-
tions were measured at 120 K (Rint = 0.0381). The structure was
solved by direct methods (SHELXS-97)[31] and refined on F2 by
full-matrix least squares (SHELXL-97)[32] of 278 parameters. All
non-hydrogen atoms were refined anisotropically. The data were
corrected for absorption effects with SADABS.[33] The final param-
eters were R = ∑||Fo| – |Fc||/∑|Fo| = 0.0393 for 3571 reflections with
3
2JH,H = 13.8 Hz, JH,H = 5.6 Hz, 4 H, CH(CH3)CHH], 0.60 [s, 36
2
3
H, C(CH3)3], 0.54 [dd, JH,H = 14.0 Hz, JH,H = 3 Hz, 4 H,
3
CH(CH3)CHH], 0.42 [d, JH,H = 6.4 Hz, 12 H, CH(CH3)] ppm.
13C NMR (100.5 MHz, CDCl3, 20 °C): δ = 133.25 (br., Ci Ph),
133.01 (s, Co Ph), 131.06 (s, Cm Ph), 128.27 (s, Cp Ph), 66.53 (s,
POCH2), 51.08 [s, CH(CH3)CH2], 37.85 (s, POCH2CH2), 31.06 [s,
C(CH3)3], 29.83 [s, C(CH3)3], 26.02 [s, CH(CH3)], 22.86 [s,
CH(CH3)] ppm. 31P{1H} NMR (161.9 MHz, CDCl3, 20 °C): δ =
132.3 (d, JP,Rh = 162.2 Hz), –143.1 (sept. JP,F = 712.6 Hz) ppm.
Preparation of [PdCl2(1)2] (7): Ligand 1 (120 mg, 0.26 mmol) was
added to a solution of [PdCl2(PhCN)2] (50 mg, 0.13 mmol) in 2 mL
of anhydrous dichloromethane. The solution was stirred for 1 h,
then the solvent was evaporated in vacuo and the product was
washed with cold methanol and dried under vacuum overnight.
The product was obtained as a light-yellow oil. Yield: 124 mg
(87%). 1H NMR (400 MHz, CDCl3, 20 °C): δ = 4.15 (m, 12 H,
POCH2) 1.64 (m, 6 H, POCH2CHH), 1.55 (m, 6 H, CHCH3), 1.46
2
2
2
Fo Ͼ 2σ(Fo2) and wR2 = [∑w(Fo – Fc )/∑w(Fo2)2]1/2 = 0.1178.
Goodness-of-fit = 1.1. The ORTEP diagram was generated with
ORTEP-3.[34] CCDC-270199 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
2
3
(m, 6 H, POCH2CHH), 1.44 [dd, JH,H = 14.0 Hz, JH,H = 3.6 Hz,
2
3
6 H, CH(CH3)CHH], 1.03 [dd, JH,H = 14.0 Hz, JH,H = 6.4 Hz, 6
H, CH(CH3)CHH], 0.88 [d, 3JH,H = 3.2 Hz, 18 H, CH(CH3)], 0.83
[s, 54 H, C(CH3)3] ppm. 13C NMR (100.5 MHz, CDCl3, 20 °C): δ
=
66.60 (s, POCH2), 51.35 [s, CH(CH3)CH2], 39.77 (s,
Supporting Information (see footnote on the first page of this arti-
POCH2CH2), 31.29 [s, C(CH3)3], 30.18 [s, C(CH3)3], 26.15 [s, cle): HPNMR and HPIR spectra of systems [Rh(acac)(CO)2]/1–3.
1074 Eur. J. Inorg. Chem. 2006, 1067–1075
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Rh-Catalysed Hydroformylation of 1-Octene
FULL PAPER
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Received: September 7, 2005
Published Online: January 3, 2006
Eur. J. Inorg. Chem. 2006, 1067–1075
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1075