Heteroatom-substituted secondary phosphine oxides (HASPOs) as decomposition products and preligands in rhodium-catalysed hydroformylation

Article abstract of DOI:10.1002/chem.201002823

O,O′-3,3′-Di-tert-butyl-5,5′-dimethoxy-1, 1′-biphenyl-2,2′-diyl phosphonate (1) is the hydrolysis product of several mono- and bis-phosphites used as ligands in industrial hydroformylation and other catalytic reactions. As a result of a tautomeric equilibrium, this pentavalent heteroatom-substituted phosphine oxide (HASPO) can rearrange to the corresponding trivalent phosphorus compound. The latter is able to react with typical rhodium-containing precursors frequently used for the generation of catalysts. The resulting species were characterised by NMR spectroscopy and X-ray structure analysis. Proof is given that a rhodium complex of 1 forms an active hydroformylation catalyst. Moreover, 1 can add to aldehydes, which are generated as products in the hydroformylation. Thus a broad range of subsequent reactions can be associated with the degradation of the original phosphite ligands, which has a strong influence on the overall outcome of the hydroformylation reaction.

Full text of DOI:10.1002/chem.201002823

DOI: 10.1002/chem.201002823
Heteroatom-Substituted Secondary Phosphine Oxides (HASPOs) as
Decomposition Products and Preligands in Rhodium-Catalysed
Hydroformylation**
[
a, b]
[a]
[a]
[c]
Andrea Christiansen,
Detlef Selent, Anke Spannenberg, Martin Kçckerling,
[a] [a] [b]
[
c]
Helmut Reinke, Wolfgang Baumann, Haijun Jiao, Robert Franke, and
[
a, c]
Armin Bçrner*
Dedicated to Dr. Klaus-Diether Wiese, who initiated the “Hydroformylation Project”
Abstract: O,O’-3,3’-Di-tert-butyl-5,5’-di-
methoxy-1,1’-biphenyl-2,2’-diyl phos-
able to react with typical rhodium-con-
taining precursors frequently used for
the generation of catalysts. The result-
ing species were characterised by NMR
spectroscopy and X-ray structure anal-
ysis. Proof is given that a rhodium com-
plex of 1 forms an active hydroformy-
lation catalyst. Moreover, 1 can add to
aldehydes, which are generated as
products in the hydroformylation. Thus
a broad range of subsequent reactions
can be associated with the degradation
of the original phosphite ligands, which
has a strong influence on the overall
outcome of the hydroformylation reac-
tion.
phonate (1) is the hydrolysis product of
several mono- and bis-phosphites used
as ligands in industrial hydroformyla-
tion and other catalytic reactions. As a
result of a tautomeric equilibrium, this
pentavalent
heteroatom-substituted
Keywords: homogeneous catalysis ·
phosphine oxide (HASPO) can rear-
range to the corresponding trivalent
phosphorus compound. The latter is
hydroformylation
·
phosphorus
heterocycles · P ligands · rhodium
Introduction
the price of the catalytically active metal, the cost of the
phosphorus ligand also plays a pivotal role in evaluating the
economic set-up of a hydroformylation process in industry.
Interestingly, up to now the stability of phosphorus li-
The n-regioselective hydroformylation of olefins in the pres-
ence of cobalt or rhodium complexes is the most industrially
applied homogeneous catalysed reaction.
[1,2]
[3]
To adapt the
gands has seldom been a focus of empiric studies. In par-
stereochemical and electronic properties of the metal centre
to the olefinic substrate mainly trivalent phosphorus ligands
with varying steric and electronic properties are employed.
As a result of this fine-tuning, excellent yields and selectivi-
ties of the desired aldehydes can be achieved. Apart from
ticular, the interest of academic researchers has been low. In
the literature it is mainly the effects of reaction parameters
like regioselectivity, turnover frequency (TOF) or turnover
number (TON) that have been addressed. In general it is as-
sumed that the catalytic properties induced by the ligand
stay constant throughout the whole reaction process. This
assumption does not reflect the possibility of ligand degra-
dation under real reaction conditions. For example, most
phosphines are prone to oxidation, which leads to pentava-
lent phosphorus compounds. Hence the coordination ability
of the phosphorus is lost. As a result, unmodified metal car-
bonyl complexes emerge and dominate the hydroformyla-
tion reaction. In the worst case, a loss of the precious metal
by the formation of catalytically inactive clusters and final
metal deposition take place.
[
a] Dr. A. Christiansen, Dr. D. Selent, Dr. A. Spannenberg,
Dr. W. Baumann, Dr. H. Jiao, Prof. Dr. A. Bçrner
Leibniz-Institut fꢀr Katalyse an der Universitꢁt Rostock e.V.
A.-Einstein-Str. 29a, 18059 Rostock (Germany)
Fax : (+49)381-12815202
E-mail: armin.boerner@catalysis.de
[
b] Dr. A. Christiansen, Priv.-Doz. Dr. R. Franke
Evonik Oxeno GmbH, Paul-Baumann-Str. 1, 45772 Marl (Germany)
[
c] Prof. Dr. M. Kçckerling, Prof. Dr. H. Reinke, Prof. Dr. A. Bçrner
Institut fꢀr Chemie, Universitꢁt Rostock
In particular, ligands with PÀO bonds, like phosphinites,
A.-Einstein-Str. 3a, 18059 Rostock (Germany)
phosphonites and phosphites, readily react with water,
which is increasingly generated by aldol condensation of
[
**] Decomposition of P-Ligands During Rh-Catalysed Hydroformylation,
Part IV; for Parts I–III, see refs. [8],[9a],[10].
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FULL PAPER
product aldehydes under the elevated temperatures usually
employed. The hydrolysis produces in the first step pentava-
lent phosphorus compounds (B, Scheme 1), which can be ab-
breviated as SPOs (secondary phosphine oxides) or
HASPOs (heteroatom-substituted phosphine oxides) ac-
The aim of our research was to investigate the equilibrium
of 1B and 1C and to study the coordination properties of
1C with typical rhodium complexes. Moreover, the reactivi-
ty of 1 towards olefins and aldehydes, which are key players
in the hydroformylation reaction, was elucidated. Finally,
the effect of a typical metal complex in the hydroformyla-
tion of selected linear olefins will be discussed.
[4]
cording to Ackermannꢃs suggestion.
Results and Discussion
State of the equilibrium: The free-energy difference for the
equilibrium between 1B and 1C in the gas phase was calcu-
À1
Scheme 1. Formation of trivalent PÀOH species by hydrolysis of PÀOR
lated by DFT methods to be À5.56 kJmol (Scheme 3).
bonds and subsequent coordination to rhodium.
This corresponds to a strong dominance of 1B (90%).
As a result of the tautomeric equilibrium shown in
Scheme 1, the (HA)SPOs (B) can coordinate to metal
atoms through their trivalent tautomers C, therefore we pro-
[5]
posed the term pre
ACHTUNGTRENNUNGl i ACHTUNGTRENNUgGN and. For a few years their ability to
act as ancillary ligands in a number of metal-catalysed reac-
[4,6]
tion has been evidenced.
Remarkably, van Leeuwen and
co-workers utilised HASPOs in platinum-catalysed hydro-
Scheme 3. Tautomeric equilibrium between 1B and 1C.
[7]
formylation reactions, which suggests that the catalytic
impact of such degradation products should not be underes-
timated.
In THF solution this equilibrium is shifted even more to-
3
1
wards 1B: in the P NMR spectrum only the resonance of
31
Recently we investigated the electronic and steric effects
of a set of SPOs that can be considered as decomposition
the pentavalent tautomer 1B was observed [ P NMR
[15,16]
(162 MHz, CD Cl , 258C): d=11.3 ppm].
2
2
[8]
products of phosphinites. Typical features like NMR and
IR spectroscopic properties as well as the shift of the equi-
librium depicted in Scheme 1 were considered. Subsequent-
ly, the reactions of SPOs with different rhodium sources
The structure of the pentavalent tautomer 1B was unam-
biguously proven by X-ray structure analysis. Figure 1 shows
the molecular structure; important bond lengths and angles
derived from the crystal structure as well as those calculated
at the B3LYP/6-311+G* level of theory are detailed in the
legend; good agreement is found between the calculated
and measured values with differences of less than 0.04 ꢄ.
The PÀO distance of 1.455(3) ꢄ clearly indicates a double
[9]
were elucidated. Moreover, it was found that, depending
upon their coordination properties, most of these SPOs
[10]
form active hydroformylation catalysts.
As a result of the known high sensitivity towards oxygen
and the relatively low activity of pertinent rhodium–phos-
bond between the phosphorus and oxygen atoms. The dihe-
dral angle between the two aromatic planes is 51.0(1)8.
[11]
phinite or –phosphine catalysts,
search has been dominated by phosphites.
hydroformylation re-
[1,2]
For example,
I
ligands bearing the bulky O,O’-3,3’-di-tert-butyl-5,5’-dime-
thoxy-1,1’-biphenyl-2,2’-diyl phosphite subunit I (Scheme 2)
have been extensively studied in technical hydroformylation
Reactions with metal complexes: For the preparation of Rh
complexes two different pathways were investigated. To
avoid the subtle equilibrium shown in Scheme 3, in the first
approach the corresponding trivalent phosphorchloridite 2
[12,13]
[14]
reactions
and also in other metal-catalysed reactions.
I
Cleavage of the POÀR bond of I by hydrolysis gives
was treated with Rh precursors. In accordance with the syn-
[17]
HASPO 1B.
thesis of a related Pt ACHUTNGRNEUNG( HASPO) complex we aimed to re-
place the halogen by hydrolysis
with water after coordination to
the metal.
In the first trial, [Rh-
AHCTUNGRTNNEG(U C H ) Cl] was treated with
2 4 2 2
4
equiv of 2 to yield the orange-
coloured dinuclear rhodium
complex 3 with the liberation of
highly
volatile
ethylene
(
Scheme 4).
Scheme 2. Ligands based on the products of the hydrolysis of the O,O’-3,3’-di-tert-butyl-5,5’-dimethoxy-1,1’-bi-
phenyl-2,2’-diyl phosphite unit (I).
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2121

A. Bçrner et al.
2
Scheme 6. Reaction of HASPO 1 with [Rh ACTHUNGTRNEUNG( cod)Cl] at room tempera-
ture.
precipitation and the resulting orange crystals could be han-
dled in air without decomposition.
Figure 1. Molecular structure of 1B (thermal ellipsoids at the 30% prob-
ability level). Selected bond lengths [ꢄ] and angles [8]: a) determined by
X-ray analysis: P1ÀO1 1.455(3), P1ÀO2 1.583(2), P1ÀO3 1.583(2), O2-P1-
O3 106.4(1); b) calculated by DFT: P1ÀO1 1.4718, P1ÀO2 1.6219, P1ÀO3
Crystals of the dimeric rhodium complexes 3 and 4 suita-
ble for X-ray analysis were obtained. Comparable PÀRh
and PÀO bond lengths as well as P-Rh-P angles are noted
1
.6207, O2-P1-O3 104.83.
for both complexes (Figure 2).
Unfortunately, all attempts
to selectively hydrolyse the PÀ
Cl bonds in complexes 3–5
failed. Neither the reaction in
aqueous alcoholic solution nor
the presence of amines as HCl
scavengers gave the desired
complexes. In several instances
decomposition took place.
As an alternative to the for-
mation of the targeted rhodi-
um complexes of 1 the direct
complexation of HASPO
with rhodium was elucidated.
The reaction of [Rh(cod)Cl]
1
2 2
Scheme 4. Synthesis of [Rh(2) Cl] (3).
ACHTUNGTRENNUNG
2
with 2 equiv of 1 in THF yield-
The same complex could be generated from the reaction
of [Rh(cod)Cl] with a six-fold amount of phosphorchlori-
dite 2. However, the yield of 3 was only moderate (50%).
When the ratio of ligand to [Rh(cod)Cl] was reduced to 1,
in addition to orange [Rh (2) (cod)Cl ] (4), the mono
ed several rhodium complexes (Scheme 6). In addition to
[9a]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
quasi-chelate
crystals from the reaction of 1 with [Rh
complex 6, which was also isolated as red
(acac)(cod)] (see
2
A
H
U
G
E
N
N
ACHTUNGTRENNUNG
A
H
U
G
R
N
U
G
below), the dimeric “head-to-head” complex 7 was pro-
2
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
A
H
U
G
R
N
U
G
duced as yellow crystals. The latter has been already charac-
2
2
2
[19,20]
terised by Faraone and co-workers.
Our own single-crys-
[18]
90% (Scheme 5).
All new compounds were isolated by
tal X-ray determination of the dimeric complex 7 confirmed
[21]
their results.
In the reaction of HASPO 1
with [Rh(acac)(cod)] in THF at
A
H
U
G
R
N
U
G
ACHTUNGTRENNUNG
room temperature the initially
generated rhodium complex 6
formed an equilibrium with
complex
8
(Scheme 7). The
latter belongs to the class of
rarely observed head-to-tail
[22]
complexes; it was isolated by
precipitation after a few hours
of reaction. The head-to-tail
complex 8 and the head-to-
head dimer 7 exhibit almost the
2
Scheme 5. Reaction of phosphorchloridite 2 with [Rh ACHTUGNTRNEUN(G cod)Cl] .
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Rhodium-Catalysed Hydroformylation
FULL PAPER
Figure 3. Molecular structure of the homobimetallic complex 8 (thermal
ellipsoids at the 30% probability level; hydrogen atoms have been omit-
ted for clarity). Selected bond lengths [ꢄ] and angles [8]: Rh1ÀP1
2
9
.271(1), Rh1ÀO3 2.090(2), P1ÀO3 1.509(3), P1ÀO2 1.626(2), P1-Rh1-O3
2.83(7), O1-P1-O2 100.5(1).
metric “head-to-tail” complex 8, as determined by single-
crystal X-ray analysis, is shown in Figure 3.
In addition to the employment of different Rh catalyst
I
precursors for the formation of Rh–HASPO complexes,
their coordination chemistry, depending on temperature and
solvent, was the subject of our investigations. Whereas the
reaction of HASPO 1 ith [Rh ACHNTUGRENNUG( acac) ACHTNUGTRENNGNU( cod)] in THF at room
temperature generated rhodium complex 6 in equilibrium
with complex 8 (Scheme 7), treatment of HASPO 1 with
[Rh
ACTHUNGTNERNUNG( acac) ACHTUNGERTNNUNG( cod)] in toluene at 1208C led to the initial forma-
tion of the quasi-chelate cod complex 6 (Scheme 8) as well
Figure 2. Molecular structures of 3 and 4 with selected bond lengths [ꢄ]
and angles [8] (thermal ellipsoids at the 30% probability level; for better
visibility the hydrogen atoms have been omitted and two of the four li-
gands in 3 are drawn in a lighter colour). Complex 3: Rh1ÀP1 2.1502(6),
Rh1ÀP2 2.1496(6), P1ÀCl2 2.0501(9), P2ÀCl3 2.0481(9), P1-Rh1-P2
9
2
7.48(2). Complex 4: Rh1ÀP1 2.1439(8), Rh1ÀP2 2.1532(8), P1ÀCl3
Scheme 8. Reaction of HASPO 1 with [Rh
208C.
ACTHUNGTRENNUNG( cod) ACHTUGNTRENNUNG( acac)] in toluene at
.052(1), P2ÀCl4 2.044(1), P1-Rh1-P2 98.37(3).
1
as some dimeric species. After prolonged heating at 1208C,
6
cod complex 6 was converted into the rhodium–h -toluene
complex 9, as was evident by monitoring the reaction by
[23,24]
NMR spectroscopy.
À
In several cases cationic rhodium complexes with BF4 as
counterion were used as catalyst precursors in the hydrofor-
mylation reactions. When we treated HASPO 1 with [Rh-
Scheme 7. Reaction of HASPO 1 with [Rh ACHUTNGRENNUG( cod) ACTHUNGTRENNUNG( acac)] in THF at room
temperature.
AHCTUNGTNERNUG( cod) ]BF , instead of the quasi-chelate complex 6, the zwit-
2 4
terionic BF -bridged complex 10 was isolated as an orange
2
[25–27]
solid in a yield of 92% (Scheme 9),
the reactions of related SPO–Rh complexes.
The reaction of [Rh(CO) (acac)] with 4 equiv of HASPO
which is similar to
3
1
[9a]
same chemical shifts in the P NMR spectra (112.6 and
14.0 ppm, respectively), but are easily distinguished by
1
ACHTUNGTRENNUNG
2
their different line patterns. An AA’XX’ pattern is observed
for complex 8 but a simple doublet of doublets for 7 because
the rhodium nuclei are chemically and magnetically non-
equivalent in the latter. The molecular structure of the sym-
1 gave the corresponding dicarbonyl rhodium complex 11 as
yellow crystals, as has already been described by Faraone
[19]
and co-workers (Scheme 10).
The formation of this bis-
ligand complex is in contrast to the reactions of sterically
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2123

A. Bçrner et al.
[
a]
Table 1. Results of the hydroformylation of n-octenes with a catalyst
[
b]
based on HASPO 1 and “naked” rhodium.
Run Ligand (CO/H Aldehyde
bar]
p
[
A
H
U
G
R
N
N
2
)
n-Regioselectivity
[c]
[d]
[%]
[%]
1
2
3
4
1
1
20
50
29
93
26
93
31
28
30
29
none 20
none 48
2 4
Scheme 9. Reaction of HASPO 1 with [Rh ACHTUNGTRENNNU(G cod) ]BF .
[
a] Composition: 3.3% 1-octene, 48.4% (Z/E)-2-octene, 29.2% (Z/E)-3-
octene, 16.4% (Z/E)-4-octene. [b] Conditions: precatalyst: [Rh(acac)-
(cod)] in toluene at 1208C, 4 h; Rh/L=1:4, Rh/olefin=1:2000, 100 ppm
Rh]. [c] Determined by GC with toluene as internal standard. [d] Pro-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
[
portion of n-nonanal relative to the overall yield of aldehydes.
As clearly indicated in Table 1, the two catalytic systems
show similar results at 20 and 50 bar after four hours of re-
action time; after raising the syngas pressure fast conver-
sions were obtained. However, the gas consumption curves
in Figure 4 show clearly that in the presence of HASPO 1
Scheme 10. Reaction of HASPO 1 with [Rh(CO) ACHUTNRGNENUG( acac)].
less demanding SPOs in which tetra-ligand complexes were
[9a]
formed.
Unfortunately, several attempts at recrystallisa-
tion did not liberate complex 11 from minor contamination
with other rhodium complexes.
HASPO 1 as pre
prove the catalytic effect of rhodium complexes of HASPO
the latter was tested as a preligand in the hydroformyla-
ACHTUNGTRENNUNGl i ACHTUNGTRENNUNGg and in hydroformylation reactions: To
1
A
T
U
G
T
E
N
N
A
H
T
N
T
R
N
U
G
tion of linear olefins. In preliminary investigations, Faraone
and co-workers used rhodium complexes of 1 in the hydro-
[19]
formylation of the less reactive substrate styrene. In com-
parison with an unmodified catalyst generated from [Rh-
ACHTUNGTRENNUNG( acac) ACHTUNGTRENNUNG( cod)] and syngas they did not observe any catalytic
Figure 4. Consumption of syngas in the hydroformylation of n-octenes
with a rhodium catalyst based on HASPO 1 (Rh/1=1:4) and “naked”
rhodium (50 and 48 bar, respectively; T=1208C; t=0 min corresponds to
[28]
effect.
In our investigations the precatalyst was likewise generat-
ed in situ by the reaction of 1 with [Rh(acac)(cod)]. Surpris-
ingly, in the reaction of 1-octene [THF, 1008C, 50 bar syngas
CO/H =1:1), 4 h, Rh/olefin=1:8000, 26 ppm (wt.) Rh, Rh/
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
the addition of olefins to the preformed catalyst solution). Gas consump-
À1
tion was measured with a mass flow meter in mLmin
.
(
2
1
=1:4)], the olefin underwent a conversion of 91% to give
aldehydes with 38% regioselectivity in favour of the forma-
tion of the terminal aldehyde. Under identical reaction con-
ditions the isolated rhodium complex 6 showed a similar hy-
droformylation performance, whereas application of head-
to-tail complex 8 led to a dramatic decrease in olefin con-
version.
In a subsequent trial a mixture of n-octenes, which repre-
sents a starting material of industrial importance, was sub-
jected to the same conditions (Table 1). At 20 bar syngas
pressure in toluene as solvent only a low yield of aldehydes
was obtained. In contrast, hydroformylation at 50 bar syngas
pressure led to a dramatic increase in catalyst activity, as
was evident from gas consumption curves and GC product
analysis (Table 1, runs 1 and 2). To determine whether the
formation of the Rh–1 catalyst can compete with an un-
modified rhodium catalyst, the latter, which can be consid-
ered as an inorganic degradation product of the original P-
ligand-modified catalysts, was also employed under these
conditions (runs 3 and 4).
the hydroformylation of n-octenes is catalysed faster than
[29]
with “naked” rhodium.
The rate constant observed for
the reaction with the ligand-modified rhodium complex is
À1
0.03523 min , whereas that of the unmodified catalyst is
À1
only 0.02038 min . This comparison shows the accelerating
effect of HASPO 1. After 4 h of reaction, the same yields
were noted. Also, the n-regioselectivities did not differ sig-
nificantly, which indicates that an n-regiodirecting effect of
the mutual quasi-chelate in the rhodium complex of 1 does
not operate under these conditions.
Reaction of HASPO 1 with product aldehydes and olefins:
HASPOs bearing acidic PÀH units are able to react with al-
[
30–32]
dehydes and olefins.
In contrast to the reactions of re-
[10]
lated SPOs, HASPO 1 added to n-nonanal or n-hexanal
only at temperatures above 1008C to give a-hydroxyphos-
phonic acid diesters 12a,b (Scheme 11).
Reaction of 1 with a 10-fold excess of aldehyde at 1008C
in toluene as solvent for 12 h gave only a yield of 52% for
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Rhodium-Catalysed Hydroformylation
FULL PAPER
ester. Therefore this side-reaction can be excluded with
HASPO 1.
Conclusion
Scheme 11. Reaction of HASPO 1 with n-nonanal and n-hexanal.
The catalytic importance of O,O’-3,3’-di-tert-butyl-5,5’-dime-
thoxy-1,1’-biphenyl-2,2’-diyl phosphonate (1) as a decompo-
sition product of prominent mono- and bidentate ligands
used in hydroformylation catalysts has been investigated.
Although the tautomeric equilibrium of this HASPO 1 is
dominated by the pentavalent structure 1B, it is capable of
both a-hydroxyphosphonic acid diesters 12a,b. In neat alde-
hyde solution the same yield was noted after only 4 h, which
shows a remarkable dependency of the reaction rate on the
[33]
aldehyde concentration. As illustrated in Figure 5 the re-
I
coordinating as trivalent phosphoric acid ester 1C to Rh
complexes to form several ligand-modified mono- and dinu-
clear rhodium complexes. Some of the investigated rhodium
complexes are typical precursors of active hydroformylation
catalysts. Exemplarily, such a catalyst was formed by the re-
action of [Rh ACHUTNERGNNUG( acac) ACHTUNGERTNNUNG( cod)] with 1 and exhibited in compari-
son with “naked” rhodium a superior initial activity and
moderate n-regioselectivity in the hydroformylation of 1-
octene and n-octenes. Moreover, HASPO 1 can react with
aldehyde products to form strongly acidic a-hydroxyphos-
phonic acid diesters. The latter are able to promote the
cleavage of PÀO bonds and hence the concentration of P-li-
gands in the reaction mixture is lowered. This may finally
lead to the loss of catalytically active rhodium species
through the formation of clusters and metal deposition.
Therefore such degradation procedures should be taken into
account when considering the overall catalytic effect of li-
Figure 5. Reverse PÀH addition of HASPO 1 from a-hydroxyphosphonic
acid diesters 12a,b in toluene at 1208C.
[36]
gands containing hydrolysable PÀO bonds.
[34]
action is reversible. At a conversion of 52%, excess of the
aldehyde was distilled off in vacuo at 608C and the remain-
ing mixture of HASPO 1 and a-hydroxyphosphonic acid
diester was dissolved in toluene. Under stirring at 1208C the
reverse reaction of the a-hydroxyphosphonic acid diesters
took place to yield HASPO 1. The chain length of the alde-
hydes clearly has no effect.
Experimental Section
General procedures: Unless stated otherwise, all the reactions were car-
ried out under an inert atmosphere (argon 5.0) using standard Schlenk
techniques. The solvents were dried by conventional procedures and dis-
tilled under an argon atmosphere. When possible, the reactions were
monitored by NMR spectroscopy. The yields listed below are isolated
yields, melting points are uncorrected. NMR spectra were recorded at
ambient temperature on Bruker AC 250, AV 300 and AV 400 MHz spec-
trometers. Chemical shifts are reported in ppm relative to TMS, solvent
signals (dichloromethane, d =5.32 ppm, d =53.8 ppm) were used as sec-
Interestingly, the illustrated reverse PÀH addition reaction
also occurred in the presence of aldehyde. With a 10-fold
excess of aldehyde in a solution of 12a and 12b in toluene
at 1008C the equilibrium reached 86% conversion. It was
shifted towards HASPO 1 at 1208C, the mixture now con-
taining only 74% of the a-hydroxyphosphonous acid die-
ster.
H
C
1
13
31
ondary reference for H and C NMR spectroscopy. P NMR spectra are
referenced to external H PO and Rh NMR spectra to X=3.16 MHz.
3 4
1
03
Mass spectra were recorded on an AMD 402 spectrometer.
Hydroformylation procedure: Hydroformylation experiments were car-
ried out in a 200 mL autoclave equipped with a thermocouple, a Bronk-
horst hitec mass flow meter and a Bronkhorst pressure controller at 100–
Irrespective of the equilibrium depicted above it can be
assumed that a certain amount of a-hydroxyphosphonic acid
diester is always present in the reaction mixture during the
hydroformylation reaction. Owing to the acidic nature of
these compounds they are able to catalyse the decomposi-
tion of the originally applied ligand by hydrolysis!
2
1208C and 20–50 bar syngas (99.997%; CO/H =1:1) for 4 h at constant
pressure. Synthesis gas was introduced through a gas entrainment impel-
ler at 1500 rpm. The autoclave with the storage vessel for olefin addition
under pressure was purged and filled with argon before the catalyst solu-
tion was introduced into the reactor and the olefin to the storage vessel
(argon counter-current). In a typical experiment, olefin (15 mL) and cata-
lyst solution (41 mL) were used with an olefin/rhodium ratio of 2000. The
catalyst solution was heated under synthesis gas to the desired reaction
temperature for 30 min. After olefin addition the pressure was kept at 20
or 50 bar and gas consumption was measured with a mass flow meter.
After 4 h of reaction the autoclave was cooled to room temperature and
then the pressure was released. Product analysis was performed by gas
Finally, the addition of HASPO 1 to 1-octene was tested.
As described by Han and Carpentier and their co-workers,
HASPOs can add to olefins and thus in our case a further
[35]
loss of ligating P-compounds would occur. However, the
reaction in neither the absence nor the presence of rhodium
complexes afforded the expected alkyl phosphorous acid
Chem. Eur. J. 2011, 17, 2120 – 2129
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2125

A. Bçrner et al.
1
3
chromatography on a HP 5890 Series II equipped with a PONA column
0.5 mm, length 50 m; 0.2 mm diameter). For this purpose the reaction so-
72H; C
A
H
U
G
R
N
N
(CH
3
)
3
); C NMR (76 MHz, CD
2
Cl
2
): d=156.3, 143.3, 132.5,
(
6 2
114.0 (4 m, C H , several quaternary C atoms could not be detected due
lution (1 mL) was diluted with n-pentane (10 mL) and toluene was used
as internal standard.
3 3 3
to low signal intensity), 55.8 (OCH ), 35.6 (m, C ACHNUTGTNERN(GU CH ) ), 32.1 ppm (m, C-
3
1
A
H
U
G
R
N
U
G
3
3
P NMR (121 MHz, CD Cl ): d=158.2 ppm (d, JRh,P
2
2
=
3
23.0 Hz); elemental analysis calcd (%) for C88
H
112Cl
6
O
16
P
4
Rh
2
: C 53.70,
X-ray crystal structure analysis: X-ray Diffraction data of single crystals
of compounds 1, 3, and 4 were measured on a APEX-X8 diffractometer
H 5.74, P 6.29, Rh 10.46, Cl 10.81; found: C 53.64, H 5.85, P 6.15, Rh
10.52, Cl 10.93.
[
21]
(
Bruker-Nonius), those of compounds 7
and 8 were measured on a
STOE-IPDS diffractometer, all with graphite monochromated MoKa radi-
Rhodium dimer 4: Chloridite 2 (9.9 mL, 0.1m in THF, 0.99 mmol) was
ation (l = 0.71073 ꢄ). All structures were solved by direct methods by
2
added slowly to a solution of [Rh ACHTUNGTRENNUNG( cod)Cl] (243 mg, 0.49 mmol) in THF
[
37]
[38]
using the SHELXS-97 program or SIR2004. Refinements were car-
(5 mL) at À408C. A change of colour from light yellow to orange imme-
diately occurred. After stirring for 1 h the solution was warmed to room
temperature overnight. The volatiles were removed in vacuo and the resi-
due dissolved in CH Cl (2 mL). After careful addition of Et O (22 mL)
2 2 2
and n-heptane (10 mL) 4 (309 mg, 51%) precipitated as an orange solid
2
ried out on F by full-matrix least-squares using all data (SHELXL-97
program) with all non-hydrogen atoms being treated anisotropically.
[
42]
[43]
XP and DIAMOND were used for graphical representations.
3
HASPO 1B: C22
P2
047.45(7) ꢄ , Z=2, 1calcd =1.282 gcm , m=0.161 mm , 13025 collected
H
29
O
5
P, crystal size 0.24ꢅ0.10ꢅ0.05 mm , monoclinic,
, a=9.2021(3), b=11.5043(5), c=10.2494(4) ꢄ, b=105.126(2)8, V=
after several days. Crystals suitable for X-ray structural analysis were ob-
1
3
À3
À1
1
tained by crystallisation from THF/diethyl ether. M.p. 201–2038C;
1
reflections, 3226 independent reflections (Rint =0.0946), 266 parameters,
T=173(2) K, R1=0.0444 with I>2s(I), wR2=0.0958 (all data), GOF on
H NMR (300 MHz, CD
2
Cl
2
): d=6.83 (m, 8H; C
6
H
2
), 4.29 (m, 4H;
C
C
8
H
12), 3.80 (br, 12H; OCH
3
), 2.55 (m, 4H; C H12), 1.41 ppm (m, 40H;
8
2
À3
13
F 1.033, residual electron density 0.217/À0.212 eꢄ
.
A
H
U
G
R
N
N
(CH ) and C H ); C NMR (76 MHz, CD Cl ): d=156.6, 143.2, 132.4,
3
3
8
12
2
2
3
114.1 (4 m, C H ), 79.0 (m, C H ), 55.9 (OCH ), 35.7 (m, C
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH ) ),
Complex 3: C44
H
56Cl
3
O
8
P
2
Rh, crystal size 0.28ꢅ0.20ꢅ0.13 mm , mono-
6
2
8
12
3
3 3
3
1
3
1.6 ppm (m, C
A
H
U
T
N
U
G
3
)
3
and C
8
H
2 2
12); P NMR (121 MHz, CD Cl ): d=
clinic, P2/c, a=15.7483(6), b=10.8941(4), c=28.0953(9) ꢄ, b=
3
À3
À1
1
57.9 ppm (d,
J
Rh-P =325.5 Hz); elemental analysis calcd (%) for
1
7
5
05.805(2)8, V=4637.9(3) ꢄ , Z=4, 1calcd =1.409 gcm , m=0.659 mm ,
6538 collected reflections, 11522 independent reflections (Rint =0.066),
23 parameters, T=293(2) K, R1=0.0368 with I>2s(I), wR2=0.0903
C
52
H
68Cl
4
O
8
P
2
Rh
2
: C 50.75, H 5.57, P 5.03, Rh 16.72; found: C 51.01, H
5.69, P 4.96, Rh 16.69.
[Rh(cod)(C H ClO P)Cl] (5): Choridite 2 (1.3 mL, 0.26 mmol, 0.2m in
2
THF) was slowly added dropwise to a solution of [Rh AHCUTNGRENNUG( cod)Cl] (64 mg,
2
À3
(
all data), GOF on F 1.016, residual electron density 0.559/À0.433 eꢄ
.
ACHTUNGTRENNUNG
2
2
28
4
3
Complex 4: C52
H
68Cl
4
O
8
P
2
Rh
2
, crystal size 0.31ꢅ0.26ꢅ0.19 mm , ortho-
rhombic, Pbca, a=16.1842(3), b=21.6583(3), c=31.1979(5) ꢄ, V=
0.13 mmol) in THF (1.5 mL). A change of colour from light yellow to
orange immediately occurred. After stirring for 20 min the volatiles were
3
À3
À1
1
0935.6(3) ꢄ , Z=8, 1calcd =1.495 gcm , m=0.908 mm , 149839 collect-
ed reflections, 11948 independent reflections (Rint =0.0518), 609 parame-
ters, T=295(2) K, R1=0.0346 with I>2s(I), wR2=0.0881 (all data),
removed under reduced pressure to give 150 mg (86%) of complex 5.
1
M.p. 92–938C; H NMR (300 MHz, CD
4-H), 6.70 (d, J=3.1 Hz, 2H; 6-H), 5.76 (br, 2H; C H
8
2
Cl
2
): d=7.02 (d, J=3.1 Hz, 2H;
12), 3.98 (br, 2H;
C H ), 3.81 (s, 6H; OCH ), 2.43, 2.19 (2 m, 8H; C H ), 1.59 ppm (s,
2
À3
GOF on F 1.014, residual electron density 1.150/À0.600 eꢄ
.
3
Complex 8: C60
ic, P2
804.9(10) ꢄ , Z=2, 1calcd =1.455 gcm m=0.703 mm , 41161 collected
H
80
O
10
P
2
Rh
2
, crystal size 0.35ꢅ0.15ꢅ0.10 mm , monoclin-
8
12
3
8
12
1
3
1
8H; C
C-2 and C-3), 132.3 (C-1), 115.2 (C 4), 114.8 (m, cod-CH), 113.9 (C-6),
3.6 (d, J=13 Hz, cod-CH), 55.9 (OCH ), 35.9 (C(CH ), 33.2 (m, cod-
CH ), 31.9 (C(CH ), 28.6 ppm (m, cod-CH ); P NMR (121 MHz,
3 3 2 2
ACHTUNGTRENNU(GN CH ) ); C NMR (75 MHz, CD Cl ): d=157.1 (C-5), 142.7 (2 m,
1
/n, a=9.773(2), b=13.662(3), c=21.042(4) ꢄ, b=93.36(3)8, V=
3
À3
À1
2
7
3
A
H
U
G
R
N
N
3 3
)
reflections, 6117 independent reflections (Rint =0.1102), 334 parameters,
T=200(2) K, R1=0.0422 with I>2s(I), wR2=0.0742 (all data), GOF on
3
1
2
A
H
U
G
R
N
U
G
3
)
3
2
2
À3
2 2 P, Rh
CD Cl ): d=153.1 ppm (d, J =285 Hz); elemental analysis calcd (%)
F 0.898, residual electron density 0.892/À0.730 eꢄ
.
for C30H
40Cl
2
O
4
PRh: C 53.83, H 6.02, P 4.63, Rh 15.37, Cl 10.59; found:
CCDC-741897 (1B), CCDC-741925 (3), CCDC-742835 (4) and CCDC-
C 53.89, H 6.18, P 4.56, Rh 15.66, Cl 10.48.
[Rh(cod)(C22 PO) H] (6): HASPO
added with stirring to [Rh(acac)(cod)] (50 mg, 0.16 mmol) in THF
7
40824 (8) contain the supplementary crystallographic 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.
A
H
U
G
R
N
N
H
28
O
4
2
1 (130 mg, 0.32 mmol) was
A
H
U
G
R
N
U
G
ACHTUNGTRENNUNG
(
3 mL) at À508C. Then the mixture was slowly warmed to room temp.
O,O’-3,3’-Di-tert-butyl-5,5’-dimethoxy-1,1’-biphenyl-2,2’-diyl phosphonate
After 4 days, diethyl ether (16 mL) was carefully added. The orange pre-
cipitate formed was filtered off and dried in vacuo. The mononuclear
complex 6 contained traces of the dinuclear complex 8. After recrystalli-
sation from THF/n-heptane, 122 mg (74%) of 6 were obtained. M.p. 234–
2
(
1): tert-Butanol (27 mL) was added to 6-chloro-4,8-di-tert-butyl-2,10-
[
39]
dimethoxydibenzo
A[ d,f]
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[1,3,2]dioxaphosphepine (2;
98 mg, 2.32 mmol).
The reaction vessel was closed and the solution stirred for 12 min at
room temperature. After 20 min stirring at 508C the volatiles were re-
moved in vacuo and 1 was obtained quantitatively as a white solid. M.p.
1
358C; H NMR (300 MHz, CD
2
Cl
2
): d=15.5 (very br, 1H; OH), 7.01 (d,
1
J=3.1 Hz, 4H; 4-H), 6.67 (d, J=3.1 Hz, 4H; 6-H), 5.10 (br, 4H; CH,
C H ), 3.80 (s, 12H; OCH ), 2.02 (br, 8H; CH , C H ), 1.61 ppm (s,
1
1
3
59–1618C; H NMR (400 MHz, CD
2
Cl
H,P =0.6 Hz, 2H; 4-H), 6.79 (d, J=
.1 Hz, 2H; 6-H), 3.82 (s, 6H; OCH ), 1.46 ppm (s, 18H; C(CH );
P, C =1.5 Hz, C-5), 143.3 (d,
2
): d=7.20 (d, JP-H =728.5 Hz,
4
5
H; PH), 7.04 (dd,
J
H,H =3.1 Hz,
J
8
12
3
2
8
12
1
3
3
6H; C
C-3), 142.6 (m, C-2), 132.7 (C-1), 114.6 (C-4), 113.5 (C-6), 100.8 (m,
C H ), 56.0 (OCH ), 35.9 (C(CH ) ), 32.1 (C(CH ) ), 30.4 ppm (C H );
3 3 2 2
ACHTUNGTRENNU(GN CH ) ); C NMR (75 MHz, CD Cl ): d=156.3 (C-5), 142.9 (m,
3
A
H
U
G
R
N
U
G
3 3
)
1
3
4
2 2
C NMR (75 MHz, CD Cl ): d=157.1 (d, J
P, C =3.9 Hz, C-3), 139.5 (d, JP, C =10.4 Hz, C-2), 131.9 (C-1), 115.2 (C-4),
3
2
A
H
U
G
R
N
U
ACHTUNGTRENNUNG
J
8
12
3
3
3
3
3
8
12
3
1
4
2 2 P, Rh
P NMR (121 MHz, CD Cl ): d=119.5 ppm (d, J =239 Hz); elemental
1
13.3 (d,
J
P, C =1.5 Hz, C-6), 53.0 (s, OCH
3
), 35.7 (s, C
): d=11.3 ppm; IR (KBr): n˜ =
449 cm (PÀH); elemental analysis calcd (%) for C22
P: C 65.33,
A
H
U
G
E
U
G
3
)
3
), 30.8 ppm
3
1
52 69 10 2
analysis calcd (%) for C H O P Rh: C 61.29, H 6.83, P 6.08, Rh 10.10;
found: C 61.53, H 7.16, P 5.64, Rh 10.14.
(
s, C(CH
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
À1
)
3
); P NMR (162 MHz, CD
2
Cl
2
2
H
29
O
5
H 7.23, P 7.66; found: C 65.4, H 7.10, P 7.86.
Rhodium dimer (head-to-head) (7): HASPO 1 (2 mL, 0.2m in THF,
Rhodium dimer 3: Chloridite 2 (5.14 mL, 0.1m in THF, 0.514 mmol) was
0.4 mmol) was slowly added with stirring to a solution of [Rh ACHTUNGTRENNUNG( cod)Cl]
2
[
40]
added carefully through a syringe to a solution of [Rh
A
H
U
G
R
N
N
(C
2
H
4
)
2
Cl]
2
(100 mg, 0.2 mmol) in THF (2 mL) at À788C. After stirring for 1 h at this
temperature the solution was warmed to room temp. and kept overnight.
Then the solvent were removed in vacuo and the residue dissolved in
(
0.05 g, 0.129 mmol) in THF (2 mL) at room temp. The use of a pop
valve is recommended to allow ethylene to escape in a controlled
manner. When the red reaction solution was stirred overnight complex 3
2 2
CH Cl (1 mL). After careful addition of diethyl ether (3 mL) red crystals
crystallised slowly as an orange precipitate. For complete precipitation
were formed. Addition of n-heptane (8 mL) to the mother liquor led to
the formation of crystals suitable for X-ray structural analysis within
1
the solvent was reduced to =
4
of the original volume. The solid was fil-
1
tered off, washed with diethyl ether and dried in vacuo to give 0.241 g,
95%) of 3. Crystals suitable for X-ray analysis were obtained by crystal-
20 days. H NMR (300 MHz, CD
2
Cl
2
): d=6.98 (d, J = 3.1 Hz, 4H; 4-H),
12), 3.79 (s, 12H;
, C 12), 1.83 (br,
)), 1.28 ppm (m, 4H; CH , C 12);
(
6.65 (d, J=3.1 Hz, 4H; 6-H), 4.71 (br, 4H; CH, C
OCH ), 3.50 (br, 4H; CH, C 12), 2.23 (m, 4H; CH
8H; CH , C 12), 1.72 (s, 36H; C(CH
8
H
1
lisation from CH
CD Cl ): d=6.75 (m, 16H; C
2
Cl
2
or toluene. M.p. 2958C; H NMR (300 MHz,
), 3.78 (br, 24H; OCH ), 1.39 ppm (m,
3
8
H
2
8
H
2
2
6
H
2
3
2
8
H
A
H
U
G
R
N
U
G
3
2
8
H
2126
www.chemeurj.org
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 2120 – 2129

Rhodium-Catalysed Hydroformylation
FULL PAPER
3
1
1
2
31
P NMR (121 MHz, CD
.5 Hz).
Rhodium dimer (head-to-tail) (8):
2
Cl
2
): d=114.0 ppm (dd, JRh-P =243.3 Hz, JRh-P
=
found; P NMR (121 MHz, CD
2
Cl
2
): d=117.0 ppm (d, JRh,P =197 Hz);
À1
2
IR (KBr): n˜ =2091.7, 2050.5 cm (CO).
A
solution of [(Rh
100 mg, 0.32 mmol) in THF (3 mL) was cooled to À788C. HASPO 1
261 mg, 0.64 mmol, in 3.5 mL THF) was slowly added with stirring. Then
A
H
U
G
R
N
U
G
A
H
U
G
E
N
N
n-Nonyl a-hydroxyphosphonate 12a: Nonanal (0.32 mL, 2 mmol) was
added to a solution of HASPO 1 (81 mg, 0.2 mmol) in toluene (3 mL)
and the solution was stirred for 75 h at 1008C; 85% conversion of
HASPO 1 was achieved. The solvent and excess aldehyde were distilled
off at 608C in vacuo. The product obtained contained around 15% of un-
(
(
the mixture was warmed to room temp. After 22 h, the cloudy solution
was diluted with THF (4 mL). After stirring for 23 h, a clear yellow solu-
tion was obtained. The volatiles were removed to
volume. After addition of diethyl ether (40 mL) the yellow precipitate
was filtered off and dried in vacuo to give 175 mg (88% related on rhodi-
um) of complex 8. Complex 7 and unreacted HASPO 1 were found in
the mother liquor. The formation of complex 8 was observed even at a L/
Rh ratio of 1. M.p. 3308C (decomp.); H NMR (250 MHz, CD
1
1
reacted HASPO 1. H NMR (300 MHz, CD Cl ): d=7.06 (d, J=3 Hz,
H), 7.04 (d, J=3 Hz, 1H), 6.74 (d, J=3 Hz, 1H), 6.73 (d, J=3 Hz, 1H),
=
3
of the original
2
2
1
5
1
2
3
3
.25 (br, 1H; OH), 4.17 (ddd, JH,P =3.8 Hz, JH,H =4.6 Hz, JH,H =10.1 Hz,
H; CH-OH), 3.83 and 3.82 (2 s, 6H; OCH ), 1.73 (m, 2H; CH ), 1.49
(CH ), 1.3–1.2 (m, 12H; CH ), 0.88 ppm (t, 3H;
3
2
and 1.48 (2 s, 18H; C
A
H
U
G
R
N
U
G
3
)
3
2
1
3
1
CH ); C NMR (75 MHz, CD Cl ): d=156.7 (s, C H ), 142.6 (m, C H ),
Cl
2
): d=
3
2
2
6
2
6
2
2
1
40.8 (dd, J=11.0 Hz, J=34.1 Hz, C
15.4 (d, J=14.7 Hz, CH, C ), 113.7 (d, J=22.0 Hz, CH, C
), 35.8 (d, J=15.2 Hz, C
), 31.1 (d, J=13.7 Hz, C(CH ), 29.6, 29.5, 29.4 (3
), 25.9 (d, J=13.8 Hz, CH ), 23.0 (s, CH ), 14.2 ppm (s, CH );
P NMR (121 MHz, CD Cl ): d=29.7 ppm (dt,
7.5 Hz). MS (CI pos): m/z: 433 [M+H] .
6
H
2
), 131.3 (d, J=28.0 Hz, C
6
H
2
),
7
.00 (d, J=3.1 Hz, 4H; 4-H), 6.64 (d, J=3.1 Hz, 4H; 6-H), 4.79 (br, 4H;
CH, C 12), 3.79 (s, 12H; OCH ), 3.34 (br, 4H; CH, C 12), 2.10 (m, 8H;
CH , C 12), 1.73 ppm (8H; CH 36H;
122 MHz, CD Cl ): d=155.3 (C-5), 143.2 (2 m, C-2 and C-3), 133.5 (C-
), 114.5 (C-4), 113.0 (C-6), 109.7 (m, CH, C 12), 65.4 (d, J=15 Hz, CH
12), 55.9 (OCH ), 36.2 (C(CH ), 33.6 (CH , C 12), 32.6 (C(CH ),
7.5 ppm (CH 12); P NMR (121 MHz, CD Cl ): d=112.6 ppm
AAꢃXXꢃ,
Rh-P ꢀ244 Hz); elemental analysis calcd (%) for
Rh : C 58.64, H 6.56, P 5.04, Rh 16.75; found: C 58.28, H
1
6
H
2
6
H
2
), 67.9
8
H
3
8
H
1
3
(d, JP-C =149.2 Hz, CH), 55.9 (br, OCH
2.6, 32.1 (2 s, 2 CH
br, 3 CH
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH ),
3 3
)
2
8
H
2
,
C
8
H
12
,
3
C ACHTUNGTNERUNG( CH )); C NMR
3
2
A
H
U
G
R
N
U
G
3 3
)
(
1
C
2
(
C
6
2
2
2
2
2
3
8
H
3
1
2
3
2
2
J
P, H =3.8 Hz,
P, H
J =
8
H
3
A
H
U
T
E
N
N
3
)
3
2
8
H
A
H
U
G
R
N
U
3 3
)
+
3
1
2
C
8
H
2
2
n-Hexyl a-hydroxyphosphonate 12b: The compound was obtained under
similar conditions to those described for the preparation of 12a by reac-
tion of HASPO 1 with n-hexanal. P NMR (121 MHz, CD
9.7 ppm.
J
60
H
80
O
10
P
2
2
1
2
Cl
2
): d=
.49, P 5.28, Rh 16.69.
2
6
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[h -
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH
3
C
6
H
5
)Rh(C22
H
28
O
4
PO)
(acac)(cod)] (60 mg, 0.193 mmol) in toluene
15 mL) was stirred for 35 h at 1208C. Then the solvents were removed.
2
H] (9): A solution of HASPO 1 (301 mg,
Computations: The equilibrium structures of 1B and 1C were optimised
first by performing density functional calculations at the B3LYP/6-31G*
level of theory and characterised as energy minima through frequency
calculations using the same method. The B3LYP/6-31G* structures were
further refined at the B3LYP/6-311+G* level of theory for comparison
with the X-ray data. The thermal energy correction of the frequency cal-
culations at the B3LYP/6-31G* level was added to the final Gibbs free
energies to analyse the energy equilibrium. The final Gibbs energy (G) is
the sum of relative energies from the B3LYP/6-311+G* and the thermal
corrections at B3LYP/6-31G* scaled at 298 K. The equilibrium of 1B and
0
(
.744 mmol) and [Rh
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
ACHTUNGTRENNUNG
The residue was recrystallised several times from boiling diethyl ether to
give 168 mg of complex 9 (86%). H NMR (300 MHz, CD
1
2
Cl
2
): d=14
(
very br, 1H; OH), 7.05 (d, J=3.1 Hz, 4H; 4-H), 6.74 (d, J=3.1 Hz, 4H;
-H), 5.82 (m, 1H; C ), 5.32, 5.27 (2 m, 2 H each, C ), 3.83 (s, 12H;
OCH ), 1.87 (s, 3H; CH -C ), 1.53 ppm (s, 36H; C(CH
75 MHz, CD Cl ): d=156.0 (C-5), 143.2 (m, C-2 and C-3), 133.3 (C-1),
20.5 (C toluene), 114.6 (C-4), 113.1 (C-6), 102.6, 102.1, 100.5 (3 m, CH
), 35.9 (C(CH ), 32.2 (C(CH ), 20.3 ppm (s, CH
toluene); P NMR (121 MHz, CD Cl ): d=125.3 ppm (d, JP,Rh =312 Hz).
Rh(cod)(C22 PO) BF ] (10): [Rh(cod) ]BF (121 mg, 0.3 mmol) and
6
6
H
5
6 5
H
1
3
3
3
6
H
5
A
H
N
T
E
N
G
3 3
) ); C NMR
(
1
2
2
toluene), 56.1 (OCH
3
A
H
U
G
R
N
N
3
)
3
A
H
U
G
R
N
N
3
)
3
3
1
(
C was computed on the basis of the calculated free-energy difference
3
1
2
2
DG) by the relationship DG=ÀRTlnK. All calculations were carried
[41]
[
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
H
28
O
4
2
2
A
H
U
G
R
N
N
2
4
out by using the Gaussian 03 program.
HASPO 1 (242 mg, 0.6 mmol) were dissolved in THF (11 mL) and stirred
at room temp. for 4 h. A change of colour from brown to yellow was ob-
served. Then the volatiles were distilled off and the residue dissolved in
THF. After stirring for 4 h and removal of the solvent in vacuo, the re-
Acknowledgements
sulting solid was dissolved in CH
2 2
Cl (5 mL). The solution was stirred for
3
days at room temp. and evaporated to half of the original volume. On
Financial support for this experimental research was provided by Evonik
Oxeno GmbH. One of us (A.C.) is grateful for a research scholarship
from the Degussa Stiftung. We thank Dr. O. Zayas and H. Borgwald for
their skilled technical assistance.
addition of diethyl ether (20 mL) a solid precipitated, which was filtered
off and dried in vacuo at 40–508C to give 292 mg (92%) of complex 10.
M.p. 2728C; H NMR (300 MHz, CD
1
2
Cl
2
): d=7.03 (d, J=3.1 Hz, 4H; 4-
12), 3.81 (s, 12H;
H), 6.68 (d, J=3.1 Hz, 4H; 6-H), 5.19 (br, 4H; C
OCH ), 2.09 (br, 8H; C 12), 1.61 ppm (s, 36H; C
75 MHz, CD Cl ): d=156.5 (C-5), 142.7 (C-3), 142.0 (“t”, C-2), 132.7
C-1), 114.9 (C-4), 113.7 (C-6), 104.3 (m, CH, C 12), 56.0 (OCH ), 35.9
(CH ), 31.9 (C(CH ), 30.2 ppm (CH , C 12); F NMR (282.4 MHz,
Cl B isotopomers, JP-F =7 Hz);
): d=À139.5 ppm (2 t due to
P NMR (121 MHz, CD Cl ): d=114.7 ppm (d, Rh,P =246 Hz);
]THF): d=À298 ppm; elemental analysis
Rh plus 0.3 molequiv. of CD Cl : C 57.40,
H 6.32, P 5.66, Rh 9.40; found: C 57.39, H 6.45, P 5.10, Rh 9.40.
(CO) Rh(C22 PO) H] (11): A solution of [(acac)Rh(CO)
.22 mmol) and HASPO 1 (351 mg, 0.87 mmol) in toluene (2 mL) was
8
H
1
3
3
8
H
3 3
ACHTUNGTRNENU(G CH ) ); C NMR
(
(
(
2
2
[
1] For reviews, see: a) P. W. N. M. van Leeuwen, G. van Koten in Cat-
alysis: An Integrated Approach to Homogeneous, Heterogeneous and
Industrial Catalysis (Eds.: J. A. Moulijn, P. W. N. M. van Leeuwen,
R. A. van Santen), Elsevier, Amsterdam, 1993, pp. 201–222; b) M.
Beller, B. Cornils, C. D. Frohning, C. W. Kohlpaintner, J. Mol. Catal.
A 1995, 104, 17–85; c) C. D. Frohning, C. W. Kohlpaintner in Ap-
plied Homogeneous Catalysis with Organometallic Compounds: A
Comprehensive Handbook in Two Volumes, Vol. 1 (Eds.: B. Cornils,
W. A. Herrmann), VCH, Weinheim, 1996, pp. 27–104.
8
H
3
1
9
C
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
)
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
)
3
2
8
H
1
0/11
CD
2
2
3
1
2
2
J
1
03
Rh NMR (12.6 MHz, [D
8
calcd (%) for C52
H
68BF
2
O
10
P
2
2
2
[
0
2
H
28
O
4
2
2
] (56 mg,
[
2] For reviews, see: a) Rhodium-Catalyzed Hydroformylation (Eds.:
P. W. N. M. van Leeuwen, C. Claver), Kluwer, Dordrecht, 2000;
b) G. Protzmann, K.-D. Wiese, Erdoel Erdgas Kohle 2001, 117, 235–
stirred at room temp. and after 2 h a colourless solid precipitated. Addi-
tion of toluene (0.5 mL) and brief heating to the boiling point afforded
after cooling yellow crystals of complex 11 that contained HASPO 1 as
an impurity. The latter could not be removed, even after repeated recrys-
tallisation from toluene. A comparison with literature data confirmed the
identity of 11.
7
OCH
1
1
2
40.
[3] a) P. W. N. M. van Leeuwen in Rhodium-Catalyzed Hydroformyla-
tion (Eds.: P. W. N. M. van Leeuwen, C. Claver), Kluwer, Dordrecht,
2000, pp. 243–246; b) P. W. N. M. van Leeuwen, Appl. Catal. A 2001,
212, 61–81.
[4] For reviews, see: a) L. Ackermann, Synthesis 2006, 1557–1571; b) L.
Ackermann, Synlett 2007, 0507–0526; c) L. Ackermann, R. Born,
J. H. Spatz, A. Althammer, C. J. Gschrei, Pure Appl. Chem. 2006,
[
19] 1
H NMR (300 MHz, CD
2 2
Cl ): d=16 (very br, 1H; OH),
.03 (d, J=3 Hz, 4H; 4-H), 6.75 (d, J=3 Hz, 4H; 6-H), 3.81 (s, 12H;
1
3
3
), 1.51 ppm (s, 36H; C
A
H
U
G
R
N
U
G
3
)
3
); C NMR (75 MHz, CD
2
Cl
2
): d=
56.7 (C-5), 143.0 (“t”, C-3), 141.4 (“t”, C-2), 133.4 (C-1), 115.1 (C-4),
13.6 (C-6), 56.0 (OCH ), 36.0 (C(CH ), 31.9 ppm (C(CH ); CO not
3
A
H
U
G
R
N
U
G
3
)
3
A
H
U
G
R
N
U
3 3
)
Chem. Eur. J. 2011, 17, 2120 – 2129
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2127

A. Bçrner et al.
7
8, 209–214; d) L. Ackermann in Phosphorus Ligands in Asymmet-
stituents. 1,1’-Biphenyl-2,2’-diyl phosphonate: ratio of B/C=43:57
À1
ric Catalysis, Vols. I–III (Ed.: A. Bçrner), Wiley-VCH, Weinheim,
(DG=0.17 kcalmol );
phosphonate: ratio of B/C=5:95 (DG=1.81 kcalmol ); 3,3’,5,5’-tet-
rakis(trifluoromethyl)-1,1’-biphenyl-2,2’-diyl phosphonate: ratio of
3,3’,5,5’-tetrafluoro-1,1’-biphenyl-2,2’-diyl
À1
2
1
2
008, pp. 831–847. L. Ackermann, Pure Appl. Chem. 2010, 82,
403–1413; e) L. Ackermann, A. Althammer, Chem. Unserer Zeit
009, 43, 74–83.
À1
B/C=1:99 (DG=3.49 kcalmol ).
[
[
5] N. V. Dubrovina, A. Bçrner, Angew. Chem. 2004, 116, 6007–6010;
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1
007; e) L. Ackermann, C. Wecjler, A. R. Kapdi, A. Althammer,
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7
025–7028; Angew. Chem. Int. Ed. 2010, 49, 6873–6876.
[
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[21] X-ray diffraction on crystals of 7 with n-heptane in the lattice gave a
2 2
unit cell isomorphous with that from 7 with CH Cl in the lattice ob-
[
19]
tained by Faraone and co-workers. Crystallographic data for 7 can
be obtained from the authors on request.
[
8] A. Christiansen, C. Li, M. Garland, D. Selent, R. Ludwig, A. Span-
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2
010, 2733–2741.
[
9] a) A. Christiansen, M. Garland, C. Li, D. Selent, R. Ludwig, R.
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6
[23] The h coordination mode was evidenced by a preliminary X-ray
structural analysis.
[24] There are some hints in the literature that the formation of arene
complexes can inhibit catalytic reactions, for example, the homoge-
2
010, 29, 3936–3950, and references therein.
I
[
[
[
10] A. Christiansen, C. Li, M. Garland, D. Selent, R. Ludwig, R.
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8
487–8499, and references therein.
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[26] Remarkably, only a single example of a mononuclear rhodium com-
2 2 2 2
plex has been described up to now. The [Rh(CO) ACHTUNGTRENUNNG( PR O) BF ] com-
plex was isolated in a yield of only 30%, whereas similar complexes
with metals other than rhodium could be prepared in yields of
[
18]
>75%.
[27] A second equivalent of HBF
BF : C. J. den Reijer, H. Rꢀegger, P. S. Pregosin, Organometallics
4
possibly assists in the esterification of
4
1998, 17, 5213–5215.
[28] Interestingly, DFT calculations on the catalytic cycle of ethylene hy-
[
[
droformylation on organoplatinum hydride [{(H
suggested a high efficiency of the platinum catalyst due to the rever-
sible shifts of proton in the PH OH···O=P chain inside the quasi-
2 2 3
PO) H}Pt ACHTUNGTRENNUNG( PH )(H)]
2
chelate ligand acting therefore as a molecular switch. Thus, fine-
tuning of the electron density at the catalytic centre in each reaction
step is provided. Yu. A. Ustynyuk, Yu. V. Babin, Ross. Khim. Zh.
2007, 51, 130–138.
2
95.
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4
3
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5
1
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3
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[
15] DFT calculations on related HASPOs gave evidence that the equi-
librium is strongly dependent on the electronic effects of aryl sub-
2128
www.chemeurj.org
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 2120 – 2129

Rhodium-Catalysed Hydroformylation
FULL PAPER
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[
1
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[
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[
[
[
39] For the synthesis, see: D. Selent, D. Hess, K.-D. Wiese, D. Rçttger,
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3
1
1
P{ H} NMR (162 MHz, CD
2
Cl
2
): d=172.9 ppm.
[
[
40] R. Cramer, Inorg. Chem. 1962, 1, 722–723.
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Received: October 1, 2010
Published online: January 17, 2011
Chem. Eur. J. 2011, 17, 2120 – 2129
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2129