Water-soluble iridium and rhodium complexes with tris(hydroxymethyl)phosphine and their catalysis in biphasic hydrogenation and hydroformylation

Article abstract of DOI:10.1039/a808350i

Novel water-soluble Ir and Rh complexes with tris(hydroxymethyl)phosphine catalyse the selective hydrogenation of the C=O bond of cinnamaldehyde and the hydroformylation of pent-l-ene both under biphasic conditions.

Full text of DOI:10.1039/a808350i

Water-soluble iridium and rhodium complexes with
tris(hydroxymethyl)phosphine and their catalysis in biphasic hydrogenation
and hydroformylation
a
a
a
a
b
Atsushi Fukuoka,* † Wataru Kosugi, Fumiaki Morishita, Masafumi Hirano, Louise McCaffrey, William
b
a
Henderson and Sanshiro Komiya*
a
Department of Applied Chemistry, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588,
Japan
b
Department of Chemistry, University of Waikato, Private Bag 3105, Hamilton, New Zealand
Received (in Cambridge, UK) 28th October 1998, Accepted 5th February 1999
Novel water-soluble Ir and Rh complexes with tris(hydroxy-
methyl)phosphine catalyse the selective hydrogenation of
the CNO bond of cinnamaldehyde and the hydroformylation
of pent-1-ene both under biphasic conditions.
3
using CD OD as a solvent. Similarly, only a singlet peak was
observed at d 217.6 with a half width of 5 Hz at 20 °C. On
cooling to 280 °C, the singlet peak was gradually shifted lower
to d 215.7 and slightly broadened (half width 12 Hz), and the
NMR spectral change was reversible on warming again to
20 °C. The broadening of the peak suggests that 1 is fluxional in
this temperature range. When THMP was added to 1, the peaks
of 1 and THMP were independently seen at 20 °C in the
The use of aqueous/organic biphasic systems is attracting
growing interest in catalytic reactions by transition metal
1
complexes. The biphasic systems have benefits in catalyst
3
1
1
separation and recycling, and the reduction or elimination of
organic solvents is also advantageous for the development of
economical and environmentally friendly processes. The key
for such biphasic catalysis is to use water-soluble phosphines as
ligands. Since the launch of the commercial propylene hydro-
P{ H} NMR, thus excluding the intermolecular exchange of
the ligands. In accordance with the 31P{ H} NMR, the H NMR
of 1 gave a doublet (JHP 4.5 Hz) due to CH of THMP at d 4.12
and a broad peak due to OH at d 5.53, and these peaks were
shifted to lower field than those of free THMP [CH at d 3.85 (t,
J 5.1 Hz) and OH at d 4.68 (q, J 5.1 Hz)]. The H NMR data
including integrals and elemental analysis also support the
formation of five-coordinate complex 1.
1
1
2
2
2
1
formylation process by Ruhrchemie/Rhône-Poulenc, sulfo-
nated derivatives of PPh
TPPMS) and P(C -m-SO
3
such as PPh
2 6 4 3
(C H -m-SO Na)
(
6
H
4
3
Na) (TPPTS) have been widely
3
used as ligands in hydroformylation, hydrogenation, and related
One might expect that [IrCl(THMP)
(cod)(THMP) ]Cl would also be formed in the reaction of
[IrCl(cod)] and THMP; however, in the presence of 3 equiv. of
THMP complex 1 is exclusively formed. This type of
2
]
2
or [Ir-
reactions catalysed by transition metals.1
,3
2
Tris(hydroxymethyl)phosphine, P(CH
2
OH)
3
(THMP) is a
2
highly water-soluble phosphine and has unique reactivity
towards a number of reagents to give functionalised hydroxy-
+
8a
[Ir(cod)L
[Ir(cod)(PMe
(cod)] with 3 equiv. of PMe
Similar reaction of [RhCl(cod)]
3) in THF at room temperature under N
3
] complex is known for compact phosphines, and
4
methylphosphines. Although many transition metal complexes
3 3
)
]Cl was prepared from the reaction of [IrCl-
5
8b
of THMP are known, there are limited examples of catalytic
2
3
.
reactions using the THMP complexes. Chatt et al. reported the
first examples of THMP complexes of Rh, Pd and Pt; however,
these complexes showed low catalytic activities in hydro-
genation and hydroformylation of olefins.5a Recently, Pringle
and coworkers showed high efficiency of THMP complexes of
Pt, Pd and Ni in catalytic hydrophosphination of formaldehyde,6
and biphasic hydrogenation of sorbic acid was reported using
2
with THMP (P/Rh ratio =
gave a complicated
2
mixture, and isolation of products was unsuccessful. On the
other hand, the reaction with 4 equiv. of THMP precipitated a
yellow powder, and recrystallisation from EtOH–CH
2 2
Cl gave
cis-[RhH {P(CH OH) ]Cl 2 in 74% yield based on Rh.‡ The
2
2
3 4
}
formation of the hydride complex was unexpected; however,
7
1
THMP complexes of Ru. In this study, we have prepared novel
the presence of Rh–H was confirmed by H NMR and IR. In the
1
THMP complexes of Ir and Rh, and their catalytic performances
have been tested for hydrogenation of cinnamaldehyde and
hydroformylation of pent-1-ene.
3 2
H NMR of 2 in (CD ) SO, RhH was observed at d 211.26 with
couplings to Rh and P (JRhH 120.8 Hz, JPH 12.9 Hz), which is
characteristic for cis-[RhH (PR ) ] . In the IR spectrum, nRhH
2 3 4
appeared at 2007 cm . The P{ H} NMR gave two doublets
of triplets with equal intensity at d 21.2 (JRhP 86, JPP 22 Hz) and
34.9 (JRhP 97, JPP 22 Hz), showing the cis geometry of 2. ESMS
and elemental analysis also support the structure of 2.
+
9
2
1
31
1
Reaction of [IrCl(cod)]
2
(cod = cycloocta-1,5-diene) with
THMP5 (P/Ir ratio = 3) in THF at room temperature under N
readily precipitated a white powder, which was purified by
recrystallisation from EtOH–Et to give [Ir(cod){P-
CH OH) ]Cl 1 in 91% yield [eqn. (1)]. Complex 1 was
c
2
2
O
(
2
3
}
3
The hydride origin is not clear at this moment. THMP itself
is a reactive agent, and the reactions of THMP such as
deprotonation and elimination of formaldehyde were reported
characterised by analytical and spectroscopic methods.‡ Elec-
trospray mass spectroscopy (ESMS) of 1 in MeOH at a cone
6
5f
voltage of 20 V gave a single peak at m/z 673 due to
in the preparation of THMP complexes of Pt and Ru. Other
possible hydride sources are the cod ligand, the solvents (THF,
+
[
Ir(cod)(THMP)
3
] with the same isotope pattern as calculated.
31
1
In the P{ H} NMR of 1 in (CD
3
)
2
SO, only a singlet peak was
2 2 2
EtOH, Et O and CH Cl ), or a trace of water included in the
observed at d 217.5, which was shifted lower than free THMP
reaction mixture.§ The possibility of cod is excluded, since a
quantitative amount of free cod was observed in the reaction of
at d 225.7. A variable-temperature NMR study was performed
[
RhCl(cod)]
2
with THMP (P/Rh = 4) in (CD
3 2
) SO. In the
THF
31
1
P{ H} NMR of this reaction, the resonances of 2 and THMP
[
IrCl(cod)]2 + 6 P(CH2OH)3
2 3 3
2 [Ir(cod){P(CH OH) } ]Cl (1)
room temp.
oxide (d 44) were detected, thus suggesting that a trace of water
can react with Ru intermediates to give 2 and THMP oxide.
1
When D
2
O was added to 2 in (CD
3
)
2
SO, the Rh–H and OH
peaks in H NMR were significantly decreased, and the peaks
completely disappeared in pure D O. This result shows a facile
1
†
Present address: Catalysis Research Center, Hokkaido University,
Sapporo 060-0811, Japan. E-mail: fukuoka@cat.hokudai.ac.jp
2
Chem. Commun., 1999, 489–490
489

Ph
Ph
OH
O
We are grateful to the Asia 2000 Foundation of New Zealand
for financial support.
H2
H2
4
5
Ph
O
Ph
OH
3
6
Notes and references
1
‡
Selected data: 1: H NMR [300 MHz, (CD
3
)
2
SO]: d 2.12 and 2.41 (br,
total 8H, cod CH
P(CH OH) ], 5.53 [br, 9H, P(CH
SO]: d 217.5 (s). ESMS (20 V, MeOH) m/z 673 ([Ir(cod){P-
2
), 3.90 (br, 4H, cod CHN), 4.12 [d, JPH 4.5 Hz, 18H,
31 1
2
3
2 3
OH) ]. P{ H} NMR [122 MHz,
Scheme 1
(
(
CD
CH
3
)
2
OH)
+
2
3
}
3
] ). Mp 115–117 °C (decomp.). Anal. Found: C, 29.05; H,
ClIr: C, 28.84; H, 5.55%. Molar electrical
conductivity L (MeOH, 24 °C) 9.05 S cm mol . Halogen check (the
5
.41. Calc. for C17
H O
39 9
P
3
Table 1 Biphasic hydrogenation of cinnamaldehyde catalysed by [Ir-
2
21
a
(
2 3 3
cod){P(CH OH) } ]Cl 1
Beilstein test): positive. Air-stable. Soluble in water, MeOH, EtOH,
Selectivity (%)d
2-PrOH, and Me
SO, but insoluble in benzene, hexane, acetone, or CH
Cl
SO]: d 211.26
(m, JRhH 120.8, JPH 12.9 Hz, 2H, RhH), 3.91 and 3.99 [d, JPH 4.5 Hz, total
2
.
2
1
2
2
1
2
3 2
: IR (KBr, cm ) 2007 (nRhH). H NMR [300 MHz, (CD )
Conv.
of 3 (%)
THMP/1b
c/atm
Run
H
2
T/°C
4
5
6
1
2
4H, P(CH
122 MHz, (CD
dt, JRhP 97, JPP 22 Hz, 2P, trans to P). ESMS (20 V, MeOH) m/z 601
2
OH)
3
], 5.45 and 5.51 [br, 12H, P(CH
2 3
OH)
]. 31P{ H} NMR
[
(
(
3 2
) SO]: d 21.2 (dt, JRhP 86, JPP 22 Hz, 2P, trans to H), 34.9
1
2
3
4
a
0
0
5
5
30
100
90
100
100
100
125
90
99
20
97
76
88
97
97
2
2
3
2
22
9
0
+
[RhH
2
{P(CH
2
OH)
3
}
4
] ). Mp 145–150 °C (decomp.). Anal. Found: C,
ClRh: C, 22.64; H, 6.02%. L (MeOH,
4 °C) 8.04 S cm2 mol . Halogen check (the Beilstein test): positive.
2
2
2.48; H, 5.82. Calc. for C12H O P
38 4 4
90
0.3
21
Conditions: 1 0.015 mmol, cinnamaldehyde 7.5 mmol, water/benzene = 5
Stability and solubility are similar to those of 1.
The THF solvent had no contamination of alcohols, which was confirmed
by NMR. In the preparation of 2, RhCl(THMP) was not observed in the
b
c
ml/5 ml, reaction time 24 h. Molar ratio of added THMP to 1. Initial
§
d
pressure at room temperature. (Mol of product)/(mol of converted 3) 3
4
100.
crude product but 2 was already formed in 70–80% yield with other
uncharacterised species.
H–D exchange of Rh–H with D
protic character.
2
O, indicating that Rh–H has
1 B. Cornils and W. A. Herrmann, in Applied Homogeneous Catalysis with
Organometallic Compounds, ed. B. Cornils and W. A. Herrmann, VCH,
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Adv. Organomet. Chem., 1992, 34, 219; I. T. Horvath, J. Mol. Catal. A,
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benzene media was performed as a test reaction of the catalysis
using complex 1 (Scheme 1). Selective hydrogenation of the
CNO bond would give cinnamyl alcohol 4, which is more
valuable than hydrocinnamaldehyde 5 from the CNC bond
hydrogenation and hydrocinnamyl alcohol 6 from the complete
hydrogenation of both the CNO and CNC bonds. Under the
conditions of 100 °C and 30 atm, with complex 1, the
conversion of 3 was 90% and the proportion of 4:5:6 was
1
997, 117; K. Nomura, J. Mol. Catal. A, 1998, 130, 1.
2
E. G. Kuntz, CHEMTECH, 1987, 570; B. Cornils and E. Wiebus,
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3c
1
991, 10, 2126; (d) E. Fache, C. Santini, F. Senocq and J. M. Basset,
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Sheldon, J. Chem. Soc., Chem. Commun., 1994, 2659.
2
76:2:22 (Table 1, run 1). At the H pressure of 100 atm, the
proportion was 88:2:9, with 99% conversion (run 2). The
addition of 5 equiv. of THMP to 1 at 90 atm decreased the
conversion to 20%; however, the selectivity of 4 was increased
to 97% (run 3). Interestingly, under the conditions of 125 °C and
4
5
N. J. Goodwin, W. Henderson and J. K. Sarfo, Chem. Commun., 1996,
1
551; N. J. Goodwin, W. Henderson, B. K. Nicholson, J. K. Sarfo, J.
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9
9
0 atm in the presence of 5 equiv. of THMP, the conversion was
7% and the proportion of 4:5:6 was 97:2:0.3 (run 4). The
role of added THMP in the catalytic mechanism is being
studied.
Rh complex 2 catalysed the biphasic hydroformylation
of pent-1-ene to give oxo aldehydes. Under the conditions of
2
01; (e) V. S. Reddy, D. E. Berning, K. V. Katti, C. L. Barnes, W. A.
Volkert and A. R. Ketring, Inorg. Chem., 1996, 35, 1753; (f) L. Higham,
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Commun., 1998, 1107.
1
2
00 °C, CO/H 20 atm/20 atm, water/benzene 4 ml/4 ml, and
substrate/catalyst ratio 90, pent-1-ene was quantitatively con-
verted to hexanal (43% yield) and 2-methylpentanal (57%) in
6
P. A. T. Hoye, P. G. Pringle, M. B. Smith and K. Worboys, J. Chem. Soc.,
Dalton Trans., 1993, 269.
20 h.
7 B. Drießen-Hölscher and J. Heinen, J. Organomet. Chem., 1998, 570,
141.
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Chemistry, ed. G. Wilkinson, F. G. A. Stone and E. W. Abel, 1982, vol.
In all the catalytic hydrogenation and hydroformylation
reactions, the substrates and products were recovered from the
benzene layer, and the catalysts were present in the water layer.
In order to test the catalyst stability three catalytic runs were
repeated, recycling the same water layer containing 1 or 2. No
decrease was observed in the reaction rates and product
selectivities, showing the reliable stability of THMP complexes
5
, p. 600; (b) J. S. Merola and R. T. Kacmarcik, Organometallics, 1989,
8
, 778.
9
R. A. Jones, F. M. Real, G. Wilkinson, A. M. R. Galas, M. B. Hursthouse
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1
and 2.
Communication 8/08350I
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Chem. Commun., 1999, 489–490