Supported organometallic complexes. Part XXX. Hydroformylation of 1-hexene in interphases - the influence of different kinds of inorganic-organic hybrid co-condensation agents on the catalytic activity

Article abstract of DOI:10.1016/S0022-328X(01)01313-4

A novel mono-T-silyl functionalized triphenylphosphine ligand was prepared by a simple coupling reaction of (p-aminophenyl)diphenylphosphine and 3-triethoxysilylpropylisocyanate. The corresponding carbonylchlorobisphosphinerhodium(I) complex ClRh(CO)[PPh<

Full text of DOI:10.1016/S0022-328X(01)01313-4

Journal of Organometallic Chemistry 641 (2002) 165–172
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Supported organometallic complexes
Part XXX. Hydroformylation of 1-hexene in interphases —
the influence of different kinds of inorganic–organic hybrid
co-condensation agents on the catalytic activityꢀ
Ekkehard Lindner *, Thomas Salesch, Stefan Brugger, Frank Hoehn, Peter Wegner,
Hermann A. Mayer
Institut fu¨r Anorganische Chemie der Uni6ersita¨t Tu¨bingen, Auf der Morgenstelle 18, D-72076 Tu¨bingen, Germany
Received 25 July 2001; accepted 10 August 2001
Abstract
A novel mono-T-silyl functionalized triphenylphosphine ligand was prepared by a simple coupling reaction of (p-
aminophenyl)diphenylphosphine and 3-triethoxysilylpropylisocyanate. The corresponding carbonylchlorobisphosphinerhodium(I)
complex ClRh(CO)[PPh2C6H4NHCONH(CH2)3Si(OEt)3]2 was synthesized in order to be sol–gel processed with various amounts
of different D- and T-silyl bifunctionalized co-condensation agents. The polysiloxane matrices and the active rhodium centers were
investigated by means of multinuclear solid state NMR (13C, 29Si, 31P) and dynamic NMR measurements. The rhodium
containing xerogels were applied in the hydroformylation of 1-hexene. These stationary phases show remarkable catalytic activities
independent on the solvent. An enhancement of the activities is achieved when T-silyl bifunctionalized co-condensation agents are
used to build up the carrier matrix. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Sol–gel proccess; Supported complexes; Rhodium(I); Hydroformylation; Solid state NMR spectroscopy
However, there are still specific problems with such
systems which inhibited the commercial breakthrough
1. Introduction
of these types of catalysts. They can leach from the
The anchoring of reactive centers, in particular cata-
support during the catalytic reaction. Furthermore the
lytically active transition metal complexes, to an inert
heterogenization of complexes leads to reduced mobil-
support is a field of increasing interest in terms of
ity of the reactive centers causing lower activities and
academic as well as commercial research [2–9]. Such
selectivities of the anchored catalysts compared to their
materials are able to combine the advantages of ho-
homogenous counterparts [11].
mogenous and heterogeneous catalysis: the catalyst be-
comes easily separable from the reaction products and
A versatile approach to reduce or even eliminate
these problems is the introduction of the concept of
it can be reused in several runs without an essential loss
interphase [12]. In the presence of a stationary phase
of activity. On the other hand, the reactive centers are
(e.g. an anchored metal complex) and a mobile phase
well defined and the improvement of their properties is
(solvent, gaseous or liquid reactant) a penetration of
not only empirical. Due to the homogenous character
both phases on a molecular level takes place. This state
of the catalytic reaction the activities and selectivities
is designated as ‘interphase’ since no homogenous
are high [10].
phase is formed. However, interphases are able to
imitate homogenous conditions providing favorable ac-
ꢀ Part XXIX, see Ref. [1].
* Corresponding author. Tel.: +49-7071-29-72039; fax: +49-
7071-29-5306.
tivities in different types of catalytic reactions without
any essential metal leaching. A typical approach for the
generation of stationary phases in interphase chemistry
E-mail address: ekkehard.lindner@uni-tuebingen.de (E. Lindner).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01313-4

166
E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
clear solid state NMR spectroscopy. To study the mo-
bility of the matrices and active centers detailed
dynamic solid state NMR measurements were under-
taken. The mobility of the rhodium containing xerogels
were compared with the dynamics of the sol–gel pro-
cessed phosphine prior to the employment of these
complexes in the hydroformylation of 1-hexene.
is the sol–gel process, which offers a convenient route
for the preparation of suitable polysiloxane networks
under smooth and low temperature conditions. Simul-
taneous co-condensation of T-silyl functionalized metal
complexes or ligands with various alkoxysilanes or
organosilanes provides materials, in which the reactive
centers are nearly homogeneously distributed across a
chemical and thermal inert carrier matrix [13–20]. Since
the polysiloxane-bound active centers are readily acces-
sible even for larger molecules, those kinds of inor-
ganic–organic hybrid materials are predestinated for
catalytic reactions [21–25].
Due to this fact we transferred the concept of inter-
phase to hydroformylation, which is one of the most
important industrial catalytic processes. For this aim a
novel T-silyl functionalized triphenylphosphine ligand
was prepared, introducing the spacer unit in the para-
position of only one phenyl ring. Subsequently the
catalytically active T-silyl functionalized car-
bonylchloro[bis(phosphine)]rhodium(I) complex was
synthesized. The ligand as well as the Vaska-analogous
rhodium(I) complex were condensed into matrices built
by various D- and T-silyl bifunctionalized co-condensa-
tion agents [20,26]. Structural investigations of these
novel stationary phases were carried out by multinu-
2. Results and discussion
2.1. Synthesis of the T-silyl functionalized ligand 2(T0)
and of the monomeric rhodium(I) complex 3(T0)
The triphenylphosphine analogous ligand 2(T0) was
obtained in good yields as a waxy colorless solid by the
reaction of (p-aminophenyl)diphenylphosphine (1) with
one equivalent of triethoxysilylpropylisocyanate in
dichloromethane. The modified Vaska complex 3(T0)
can be easily prepared by the reaction of 2(T0) with a
half equivalent of [m-ClRh(CO)2]2 in benzene (Scheme
1). Both compounds were characterized by 1H-,
13C{1H}-, 31P{1H}-NMR, and IR spectroscopy, as well
as mass spectrometry, and elemental analysis. In the
31P{1H}- and 29Si{1H}-NMR spectra of 2(T0) each one
signal is observed at l= −5.5 and −45.1, respec-
tively. Compared to triphenylphosphine the para-posi-
tioned spacer function exerts nearly no influence on the
chemical shift of the 31P nucleus in 2(T0). The composi-
tion of the rhodium complex 3(T0) was corroborated by
its EIMS showing the molecular peak at m/z=1214.
1
Only one doublet with a JRhP coupling constant of
124.7 Hz occurs in the 31P{1H}-NMR spectrum of
complex 3(T0), which is indicative of a trans-position of
the phosphine ligands [27]. A characteristic absorption
at 1980 cm−1 in the IR spectrum of 3(T0) is assigned to
the carbonyl stretching vibration. Other analytic data
are summarized in the experimental part.
2.2. Sol–gel processing of 2(T0) and 3(T0)
The xerogels X2a and X2b were prepared by sol–gel
processing of the monomeric T-silyl functionalized lig-
and 2(T0) with the co-condensation agent 4(D0) and
5(D0), respectively. In the case of X3a–d the rhodium
complex 3(T0) was condensed into a matrix consisting
of the co-condensation agents 4(D0), 4(T0), 5(D0), and
5(T0) (Table 1, Scheme 2). The properties of such
materials strongly depend on the reaction conditions
during the entire sol–gel process such as concentration
of the monomers, type of solvent, temperature, and
kind of catalyst. All sol–gel processes were carried out
in THF with an excess of water and tetrabutylammoni-
umfluoride as catalyst. To guarantee reproducible ma-
terials uniform reaction conditions were maintained.
Scheme 1.
Table 1
Labeling of the compounds
Precursor
Co-condensation Ideal T/D or T/T
Xerogel
agent
ratio
2(T0)
2(T0)
3(T0)
3(T0)
3(T0)
3(T0)
4(D0)
5(D0)
4(D0)
5(D0)
4(T0)
5(T0)
1:5
1:5
1:20
1:20
1:20
1:20
X2a
X2b
X3a
X3b
X3c
X3d

E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
167
2.3. Solid state NMR spectroscopic in6estigations
Due to the amorphous nature of these materials,
solid state NMR spectroscopy plays an important role
in investigating the structure and the dynamic behavior
of xerogels [28–30]. 29Si-NMR spectroscopy enables the
characterization of the carrier matrix and the degree of
condensation. 13C- and 31P CP/MAS-NMR spec-
troscopy allows an insight into the hydrocarbon regions
and the reactive center, respectively (Fig. 1).
2.3.1. 29Si CP/MAS-NMR spectroscopy and mobility
of the matrix
Scheme 2.
As a result of an incomplete condensation the 29Si
CP/MAS-NMR spectra of the above-mentioned xe-
rogels reveal signals of various substructures with cor-
responding Di- and Tn-functions. Typical chemical
shifts are l= −4.8 (D0), −14.3 (D1), −22.3 (D2),
−58.2 (T2), and −67.7 (T3). They remain unchanged
with respect to the stoichiometric composition of the
materials and the kind of co-condensate. All silicon
atoms in the polysiloxane matrix are in direct proximity
of protons, thus silyl species are detectable via cross
polarization [31,32]. Therefore the degree of condensa-
tion of D- and T-silyl functions were determined by
contact time variation experiments (Table 2) [20,33].
However, due to the very low concentration of the
T-groups in the xerogels X3a and X3b they can hardly
be detected. Therefore the quantification of these silyl
functions with contact time variation experiments is not
feasible within a reasonable time and hence was carried
out by deconvolution of the 29Si CP/MAS spectra. In
all above-mentioned xerogels the degrees of condensa-
tion range from 74 to 92% and 90 to 96% for the D-
and T-groups, respectively. These results are in agree-
ment with former investigations [34,35].
In the solid state the T/D-materials do not differ
significantly in the cross polarization constant TSiH and
the relaxation time T1rH (via 29Si) indicating that the
mobilities of the matrices in X2a, b and X3a, b are
similar. The T/T-polymers X3c and X3d show differ-
ences in the TSiH values. In both materials the number
and distance of the protons surrounding the 29Si nu-
cleus is very similar which means that the cross polar-
ization constant TSiH is only governed by the mobility.
The higher TSiH values of X3c indicate a more ineffi-
cient transfer of the magnetization of the protons to the
29Si atoms than in X3c and thus a slightly faster
motion.
2.3.2. 31P CP/MAS-NMR spectroscopy and mobility
of the reacti6e center
In the 31P CP/MAS-NMR spectra of the polysilox-
ane-bound phosphines X2a, b one signal is observed at
−6.3 and −6.7 ppm, respectively. Also, only one
broad signal with a chemical shift at about 29 ppm
Fig. 1. Solid state NMR spectra; top: 31P CP/MAS of X3d; middle:
13C CP/MAS of X2a; bottom: 29Si CP/MAS of X3a (* rotational side
bands).

168
E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
Table 2
Relative I0, TSiH, and T1rH data of the silyl species in the xerogels
Xerogel
Relative I0 data of D and T species a
Degree of
TSiH (ms) b
T1rH (ms) c
condensation (%)
D0
1.5
D1
D2
T2
6.1
T3
D
T
D0 D1
D2
T2
T3
d
d
e
e
e
e
d
d
d
d
d
d
X2a
X2b
X3a
X3b
X3c
X3d
17.4
16.1
100
100
20.8
18.7
3.9 f
8.6 f
100
100
92
92
74
82
93
96
95
95
91
90
1.24
1.45
1.28
1.43
1.83
1.11
1.15
2.02
1.52
7.1
6.8
6.3
5.8
6.0
5.1
2.0
2.6
e
100 f
91.3 f
1.3 f
1.02
e
e
e
55.2 f
100 f
1.6 f
0.96
1.22
e
e
e
e
31.6
42.2
1.15
0.67
e
e
e
e
a I0 values calculated according to Ref. [19].
b Determined by contact time variation.
c Determined via 29Si-NMR with the experiment according to Ref. [39].
d Intensity to low for a precise determination of TSiH
.
e Species not detectable.
f Determined via deconvolution of 29Si CP/MAS-NMR spectra (Tc=5 ms).
occurs in the 31P CP/MAS-NMR spectra of the
rhodium containing polymers X3a–d. These results re-
mind of the ligand and the monomeric rhodium(I)
complex measured in solution. No other phosphine
species is detectable in the freshly synthesized polymers,
but exposure to air for some hours leads to the forma-
tion of phosphine oxide.
Due to higher values of the cross polarization con-
stant TPH (Table 3) the reactive centers (free phosphine
ligand) in X2a and X2b show an enhanced mobility
compared to the polysiloxane-bound rhodium com-
plexes in X3a–d. Obviously the P-coordination of the
ligands enables a fast magnetization transfer for all
types of co-condensates. Furthermore it can be demon-
strated, that the rhodium(I) centers in the T/D-materi-
als X3a, b are slightly more mobile than those in the
T/T-polymers X3c, d. These results are in a good
agreement with former investigations [20,35].
2.4. Hydroformylation of 1-hexene in the interphase
Square-planar rhodium(I) complexes have been ap-
plied as catalysts for the hydroformylation of various
olefins for more than three decades [36–38]. In this
work the polysiloxane-bound rhodium(I) complexes
X3a, X3b, X3c, and X3d were employed in the hydro-
formylation of 1-hexene with good turnover numbers
(TON) in dichloromethane and toluene as solvents
(Tables 4 and 5). In the case of dichloromethane a
complete listing of the constituents of the reaction
solution is presented in Fig. 2. Methanol, the most
commonly solvent for catalytic hydroformylations,
leads only to acetalyzation products when the above-
mentioned catalysts were used, which could be demon-
1
strated by H- and 13C{1H}-NMR spectroscopy. It is
remarkable, that the catalytic activity in toluene is
higher than in dichloromethane. In the case of toluene
a conversion of 1-hexene of 100% for the first run of
each catalyst was achieved. This is in contrast com-
pared to the swelling capabilities of the polymers in
each solvent [26]. The selectivity does not change re-
2.3.3. 13C CP/MAS-NMR spectroscopy
The 13C CP/MAS-NMR spectra of X2a, X3a, and
X3c reveal a broad group of signals in the aromatic
region, which stems from the phenyl carbon atoms of
the functionalized phosphine ligand. The aliphatic re-
gion is dominated by three and four major signals,
respectively, which are assigned to the hydrocarbon
chain of the co-condensate. In the case of the hybrid
polymers X2b, X3b, and X3d all main signals can be
traced back to the backbone of the matrix. It is note-
worthy, that the signal occurring at about 155 ppm in
each 13C CP/MAS-NMR spectrum is attributed to the
urea function in the spacer. The weak or missing peaks
for the alkoxysilyl substituent indicate a rather high
degree of hydrolysis.
Table 3
T1rH (via 31P) and TPH parameters of the xerogels
Xerogel
T1rH [ms] a
TPH [ms] b
X2a
X2b
X3a
X3b
X3c
X3d
8.3
6.5
4.6
7.4
10.8
6.9
2.05
1.94
0.52
0.48
0.32
0.29
a Determined via 31P according to Ref. [39].
b Determined via contact time variation.

E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
169
Table 4
Hydroformylation of 1-hexene in toluene a
Catalyst
Conversion (%)
Isomerization (%)
Hydroformylation (%)
n/(n+iso)
TON b
TOF c
3(T0)
X3a
X3b
X3c
X3d
100
100
100
100
100
17.4
33.7
20.9
5.3
82.6
66.3
79.1
94.7
92.5
0.57
0.67
0.58
0.53
0.53
13216
10608
12656
15152
14800
777
624
734
891
870
7.5
a Reaction conditions: 70 °C, 30 bar CO, 30 bar H2, 1020 min, 30 ml solvent, 10 ml (80 mmol) 1-hexene, 5 mmol catalyst, ratio
catalyst–substrate 1:16000.
b Turnover number: [mol (aldehyde)/mol (catalyst)].
c Turnover frequency: {mol (aldehyde)/[mol (catalyst)/h]}.
Table 5
Hydroformylation of 1-hexene in dichloromethane a
Catalysts
Conversion (%)
Isomerization (%)
Hydroformylation (%)
n/(n+iso)
TON b
TOF c
3(T0)
X3a
X3b
X3c
X3d
66.5
88.9
69.3
100
27.7
49.5
30.7
13.0
23.9
72.3
50.5
69.3
87.0
76.1
0.69
0.72
0.69
0.58
0.65
7696
7184
7680
13920
12176
452
423
451
819
716
100
a Reaction conditions: 70 °C, 30 bar CO, 30 bar H2, 1020 min, 30 ml solvent, 10 ml (80 mmol) 1-hexene, 5 mmol catalyst, ratio
catalyst–substrate 1:16000.
b Turnover number: [mol (aldehyde)/mol (catalyst)].
c Turnover frequency: {mol (aldehyde)/[mol (catalyst)/h]}.
markably and is 0.62 (90.1) (n/[n+iso]) for all sta-
tionary phases. However, it was not the target of these
investigations to get high yields of linear aldehydes with
the simple and unspecific square-planar rhodium(I)
complex. A remarkable influence of the TONs by a
modification of the organic part from pure alkyl (X3a,
X3c) to a chain with a phenylene unit (X3b, X3d) could
not be observed. These results are in agreement with
the NMR studies of the mobility of the pure polymers
[26]. By variation of the silyl functionality in the co-
condensation agents higher conversions, in particular in
the case of dichloromethane could be detected. Co-con-
densation agents with T-silyl groups (X3c, X3d) show a
higher catalytic activity than those, which are provided
with D-silyl moieties (X3a, X3b). This result indicates
that a higher cross-linkage of the polymer does not
exert a negative influence on the accessibility of the
reactive centers in the interphase at the described cata-
lytic conditions. The lower mobility of the T-silyl func-
tionalized co-condensation agents, which was observed
by solid state and suspension NMR investigations [26],
and the swelling capability of the polymers, are evi-
dently not the significant criterions for the catalytic
activity of the reactive centers. A comparison of similar
D- and T-silyl bifunctionalized hybrid materials in the
time domain of the NMR spectroscopy is probably
unsuitable. Better comparable are results of mobility
studies, which were derived by dynamic fluorescence
spectroscopy [39]. These investigations revealed, that
polymers with the co-condensation agent 4(T0), which
are including a fluorescence active fluorene molecule,
possess a higher rotational mobility of fluorene than
polymers made of 3(T0) in the time domain of the
fluorescence spectroscopy.
Finally it is noteworthy that no leaching of the
transition metal was detectable by atomic absorption
spectrocopy.
3. Conclusions
A novel T-silyl functionalized triphenylphosphine
2(T0) was prepared by a simple coupling reaction of
Fig. 2. Composition of the solution after hydroformylation of 1-hex-
ene in dichloromethane.

170
E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
(p-aminophenyl)diphenylphosphine (1) and 3-tri-
ethoxysilylpropylisocyanate. Treatment of the modified
phosphine 2(T0) with [m-ClRh(CO)2] gave the T-silyl
functionalized rhodium(I) complex 3(T0). After sol–gel
processing with different co-condensation agents the
polymers were used in the hydroformylation of 1-hex-
ene. Although the urea function in the spacer unit can
represent a different possible reactive center, there was
no evidence of disadvantage in the application of these
kinds of materials in catalysis. For organometallic reac-
tions in interphases with substrates that attack the urea
unit (e.g. methyliodide) the ligand has to be changed
into a system without any further functional group in
the spacer unit [27].
With the application of different D- and T-silyl bi-
functionalized co-condensation agents in the hydro-
formylation of 1-hexene these various stationary phases
could be directly compared for the first time under
catalytic conditions. Altogether a higher cross-linkage
of polymers, which are provided with T-silyl bifunction-
alized copolycondensates, is more advantageous under
a pressure of 60 bar. The D-silyl bifunctionalized silox-
anes, which are more mobile on the NMR time scale
show a lower activity under these medium pressure
conditions. Properties like the swelling capability and
the mobility of the different parts of the polymer be-
come less important. The accessibility of the reactive
centers and thus the catalytic activity increase with the
more rigid polymer backbone of T-silyl bifunctionalized
co-condensation agents under the described conditions.
dard]; 13C-NMR: 50.228 MHz (4.7 T) [Me4Si, carbonyl
resonance of glycine (l=176.0) as second standard];
29Si-NMR: 39.73 MHz (4.7 T) (Q8M8 as second stan-
dard). All samples were packed under exclusion of
molecular oxygen. The cross polarization constants
TXH were determined by variation of the contact time
Tc (14–16 experiments). The proton relaxation times in
the rotating frame T1rH were measured by direct proton
spin lock-~-CP experiments [40] via 29Si-NMR and
31P-NMR. The relaxation parameters were obtained
using Bruker software SIMFIT and WINFIT following the
procedure described in Ref. [20].
All reactions and manipulations were carried out
under Ar with the usual Schlenck techniques. Methanol
was dried with magnesium and distilled prior to use. All
other solvents were distilled from sodium benzophe-
none ketyl or calcium hydride. H2O was distilled under
inert gas prior to use. All solvents and reagents were
stored under Ar. [m-ClRh(CO)]2 [41], (p-amino-
phenyl)diphenylphosphine (1) [42], and the co-conden-
sation agents 4(D0), 4(T0), 5(D0), and 5(T0) [20,26] were
synthesized as described previously.
4.2. Catalysis
The hydroformylation experiments were carried out
in a 100 ml stainless steel autoclave equipped with a
mechanical stirring bar. The autoclave was flushed with
Ar prior to the introduction of the reaction mixture (5
mmol of catalyst with respect to rhodium, 80 mmol of
1-hexene, and 30 ml of the solvent). The reaction
mixture was set under CO pressure and stirred for 30
min prior to hydrogen introduction. After stirring for 5
min the mixture was heated to the required tempera-
ture. The quantitative analyses were performed on a
GC 6000 Vega Series 2 (Carlo Erba Instruments) with
an FID and a capillary column CP Sil 88 [17 m, carrier
gas helium (50 kPa); integrator Hewlett Packard 3390
A]. Leaching investigations were carried out with a
Varian Spectr AA 20 Plus atomic absorption
spectrometer.
4. Experimental
4.1. Materials and instrumentation
Elemental analysis were carried out on a Vario EL
Analyzer (Elementar Analytische Systeme Hanau). IR
data were obtained on a Bruker IFS 48 FT-IR spec-
trometer. Solution nuclear magnetic resonance spectra
were recorded on a Bruker DRX 250 spectrometer
(field strength 5.87 T) at 296 K. Frequencies are as
1
follows: H-NMR: 250.13 MHz (referenced to Me4Si),
4.3. N-[p-(Diphenylphosphinyl)phenyl]-N%-
[(triethoxysilyl)propyl]urea [2(T0)]
13C{1H}-NMR: 62.90 MHz (referenced to Me4Si),
29Si{1H}-NMR: 49.96 MHz (referenced to Me4Si),
31P{1H}-NMR: 101.25 MHz (referenced to 85%
H3PO4), MS: FD, Finnigan MAT 711A (8 kV, 333 K),
EI, TSQ Finnigan (70 eV, 473 K) and reported as
mass/charge (m/z).
To a solution of 1 (12.6 g, 45.4 mmol) in 30 ml of
CH2Cl2 a solution of triethoxysilylpropylisocyanate
(11.2 g, 45.4 mmol) in 10 ml of CH2Cl2 was slowly
added. After stirring overnight the solvent was reduced
in vacuum and 2(T0) was obtained as a colorless waxy
solid which is sensitive to moisture and air. Yield: 21.3
g (89.4%) — 1H-NMR (CDCl3): l=7.69–7.05 (m,
14H, H-phenyl), 3.67 (q, 3JHH=6.91 Hz, 6H,
OꢀCH2ꢀCH3), 3.08 (m, 2H, NHꢀCH2ꢀCH2), 1.51 (m,
2H, CH2ꢀCH2ꢀCH2), 1.11 (t, 3JHH=6.91 Hz, 9H,
OꢀCH2ꢀCH3), 0.52 (m, 2H, CH2ꢀCH2ꢀSi) —
CP/MAS solid state NMR spectra were recorded on
Bruker DSX 200 multinuclear spectrometer equipped
with a wide bore magnet (field strength 4.7 T). Magic
angle spinning was applied at 10 kHz (4 mm ZrO2
rotors) and 3–4 kHz (7 mm ZrO2 rotors), respectively.
Frequencies and standards: 31P-NMR: 81.961 MHz (4.7
T) [85% H3PO4, NH4H2PO4 (l=0.8) as second stan-

E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
171
13C{1H}-NMR (CDCl3): l=156.1 (s, NHꢀCOꢀNH),
140.6–119.2 (m, C-phenyl), 58.5 (s, OꢀCH2ꢀCH3), 42.7
(s, NHꢀCH2ꢀCH2), 23.7 (CH2ꢀCH2ꢀCH2), 18.4 (s,
OꢀCH2ꢀCH3), 7.8 (s, CH2ꢀCH2ꢀSi) — 31P{1H}-NMR
(CDCl3): l= −5.5 — 29Si{1H}-NMR (C6D6): l=
−45.1 — IR (KBr, cm−1): 3311 [w(NH)], 1643
[w(CO)] — MS (FD); m/z: 524 [M+] — Anal.
Found: C, 64.71; H, 6.90; N, 5.07. Calc. for
C28H37N2O4PSi: C, 64.10; H, 7.11; N, 5.34%.
(br, C-phenyl), 57.8 (OꢀCH2ꢀCH3), 42.3–17.8 (br, CH2
of backbone and spacer), −0.3 (SiꢀCH3) — 29Si CP/
MAS-NMR: l= −4.8 (D0), −14.3 (D1), −22.3 (D2),
−58.2 (T2), −67.7 (T3).
Compound X2b: Initial weight of 2(T0) 101 mg (0.2
mmol) and of 5(D0) 184 mg (0.5 mmol). Yield: 162
mg — 31P CP/MAS-NMR: l= −6.7 — 13C CP/
MAS-NMR: l=156.1 (NHꢀCOꢀNH), 133.0–119.0
(br, C-phenyl), 57.7 (OꢀCH2ꢀCH3), 38.9–17.8 (br, CH2
of backbone and spacer), −0.5 (SiꢀCH3) — 29Si CP/
MAS-NMR: l= −4.9 (D0), −14.4 (D1), −21.9 (D2),
−57.5 (T2), −66.8 (T3).
4.4. Chlorocarbonyl-bis{N-[p-(diphenylphosphinyl)-
phenyl]-N%-[(triethoxysilyl)propyl]urea} rhodium(I)
[3(T0)]
Compound X3a: Initial weight of 3(T0) 73 mg (0.06
mmol) and of 4(D0) 353 mg (1.2 mmol). Yield: 321
mg — 31P CP/MAS-NMR: l=29.1 — 13C CP/
MAS-NMR: l=156.0 (NHꢀCOꢀNH), 143.8–117.6
(br, C-phenyl), 55.2 (OꢀCH2ꢀCH3), 33.3–17.6 (br, CH2
of backbone and spacer), −0.4 (SiꢀCH3) — 29Si CP/
MAS-NMR: l= −12.3 (D1), −22.0 (D2), −59.2
(T2), −68.6 (T3) — IR (KBr, cm−1): 1982 [w(CO)].
Compound X3b: Initial weight of 3(T0) 75 mg (0.06
mmol) and of 5(D0) 457 mg (1.2 mmol). Yield: 355
mg — 31P CP/MAS-NMR: l=28.9 — 13C CP/
MAS-NMR: l=156.6 (NHꢀCOꢀNH), 139.5–118.2
(br, C-phenyl), 38.8–17.1 (br, CH2 of backbone and
spacer),−0.5 (SiꢀCH3) — 29Si CP/MAS NMR: l=
−4.9 (D0), −14.4 (D1), −21.9 (D2), −57.5 (T2),
−66.8 (T3) — IR (KBr, cm−1): 1982 [w(CO)].
To a solution of [m-ClRh(CO)2]2 (0.24 g, 0.62 mmol)
in 10 ml of benzene a solution of 2(T0) (1.31 g, 2.49
mmol) in 10 ml of benzene was added dropwise. The
reaction mixture was stirred for 1 h at ambient temper-
ature. The solvent was removed in vacuum and the
residual waxy solid was dissolved in 10 ml of n-hexane.
After stirring for 30 min the solvent was removed under
reduced pressure and 3(T0) was obtained as a yellow
microcrystalline solid which is sensitive to moisture and
air. Yield: 1.49 g (98.4%) — 1H-NMR (CD2Cl2): l=
3
7.97–7.28 (m, 14H, H-phenyl), 3.71 (q, JHH=7.22 Hz,
6H, OꢀCH2ꢀCH3), 3.03 (m, 2H, NHꢀCH2ꢀCH2), 1.48
3
(m, 2H, CH2ꢀCH2ꢀCH2), 1.11 (t, JHH=7.22 Hz, 9H,
OꢀCH2ꢀCH3), 0.52 (m. 2H, CH2ꢀCH2ꢀSi) —
13C{1H}-NMR (CD2Cl2): l=156.0 (s, NHꢀCOꢀNH),
143.0–118.1 (m, C-phenyl), 58.8 (s, OꢀCH2ꢀCH3), 43.0
(s, NHꢀCH2ꢀCH2), 24.1 (CH2ꢀCH2ꢀCH2), 18.6 (s,
OꢀCH2ꢀCH3), 8.0 (s, CH2ꢀCH2ꢀSi) — 31P{1H}-NMR
Compound X3c: Initial weight of 3(T0) 50 mg (0.04
mmol) and of 4(T0) 269 mg (0.8 mmol). Yield: 237
mg — 31P CP/MAS-NMR: l=29.6 — 13C CP/
MAS-NMR: l=155.1 (NHꢀCOꢀNH), 135.8–118.3
(br, C-phenyl), 31.5–12.7 (br, CH2 of backbone and
spacer) — 29Si CP/MAS-NMR: l= −56.6 (T2),
−65.6 (T3) — IR (KBr, cm−1): 1980 [w(CO)].
1
(CD2Cl2): l=29.2 (d, JRhP=124.7 Hz) — IR (KBr,
cm−1): 3331 [w(NH)], 1980, 1693 [w(CO)] — MS (EI);
m/z: 1214 [M+], 1186 [M+−CO] — Anal. Found: C,
55.79;
H,
5.96;
N,
4.28.
Calc.
for
Compound X3d: Initial weight of 3(T0) 75 mg (0.06
mmol) and of 5(T0) 497 mg (1.2 mmol). Yield: 385
mg — 31P CP/MAS-NMR: l=29.0 — 13C CP/
MAS-NMR: l=156.1 (NHꢀCOꢀNH), 139.5–118.0
(br, C-phenyl), 37.4–12.8 (br, CH2 of backbone and
spacer) — 29Si CP/MAS-NMR: l= −56.8 (T2),
−65.6 (T3) — IR (KBr, cm−1): 1981 [w(CO)].
C57H74ClN4O9P2RhSi2: C, 56.31; H, 6.14; N, 4.61%.
4.5. General procedure for the sol–gel processing
To a solution of 2(T0), 3(T0) in 6 ml of THF the
corresponding amount of the co-condensation agent
4(D0), 4(T0), 5(D0), and 5(T0), 1.0 g (56 mmol) of H2O
and the catalyst tetrabutylammoniumfluoride (TBAF)
(0.1 ml of a 1 M solution in THF) was added. The
reaction mixture was stirred at room temperature for 24
h until a gel was formed. Subsequently the solvent was
removed under reduced pressure and the crude product
was dried for 2 h. After washing three times with
MeOH (5 ml) and n-hexane (5 ml) and drying in
vacuum for 4 h the xerogels were obtained as yellow
powders.
Acknowledgements
The support of this research by the Deutsche
Forschungsgemeinschaft (Graduiertenkolleg ‘‘Chemie
in Interphasen’’ Grant No. 441/2, Bonn-Bad Godes-
berg) and by the Fonds der Chemischen Industrie,
Frankfurt/Main is gratefully acknowledged. We thank
M. Henes, Institut fu¨r Anorganische Chemie II, Uni-
versity of Tu¨bingen, for IR measurements. Finally we
thank Degussa AG, Germany, for a generous gift of
RhCl3.
Compound X2a: Initial weight of 2(T0) 101 mg (0.2
mmol) and of 4(D0) 145 mg (0.5 mmol). Yield: 153
mg — 31P CP/MAS-NMR: l= −6.3 — 13C CP/
MAS-NMR: l=156.7 (NHꢀCOꢀNH), 139.0–118.5

172
E. Lindner et al. / Journal of Organometallic Chemistry 641 (2002) 165–172
A. Weber, T.S. Ertel, H. Bertagnolli, J. Mater. Chem. 10 (2000)
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