Accessibility studies of sol-gel processed phosphane-substituted iridium(I) complexes in the interphase

Article abstract of DOI:10.1002/1099-0682(200208)2002:8<1998::AID-EJIC1998>3.0.CO;2-X

The synthesis of the T-silyl functionalized, and therefore sol-gel processable, Vaska complex [IrCl(CO){(C₆H₅)₂PC₆ H_4- (CH₂)₄Si(OMe)₃}₂] [4(T⁰)]

Full text of DOI:10.1002/1099-0682(200208)2002:8<1998::AID-EJIC1998>3.0.CO;2-X

FULL PAPER
Accessibility Studies of Sol-Gel Processed Phosphane-Substituted Iridium(I)
Complexes in the Interphase[‡]
Ekkehard Lindner,*[a] Thomas Salesch,[a] Stefan Brugger,[a] Stefan Steinbrecher,[b]
Erich Plies,[b] Michael Seiler,[c] Helmut Bertagnolli,[c] and Hermann A. Mayer[a]
Dedicated to Professor Gottfried Huttner on the occasion of his 65th birthday
Keywords: Iridium / Immobilization / Sol-gel processes / Accessibility studies / NMR spectroscopy
The synthesis of the T-silyl functionalized, and therefore sol-
gel processable, Vaska complex [IrCl(CO){(C6H5)2PC6H4-
(CH2)4Si(OMe)3}2] [4(T0)] succeeded by reaction of [Ir(µ-
Cl)(COE)2]2 (COE = cyclooctene; 1) with the phosphane
(C6H5)2PC6H4(CH2)4Si(OMe)3 [3(T0)] in the presence of car-
bon monoxide. Subsequently, 4(T0) was co-polycondensed
reacted in the interphase systems gas/solid and liquid/solid
with HCl, Cl2, CH3I (13CH3I), Cl2HCCHCl2, SO2, O2, and
NCCϵCCN, in the course of which the xerogels X2−X7 were
formed. With the exception of the reversible species X5 (SO2)
and X6 (O2) the reactions proceeded quantitatively. The com-
position of the polymers and the structures of the reactive
with five equivalents of (MeO)3Si(CH2)3C6H4(CH2)3Si(OMe)3 centers were elucidated by means of multinuclear solid-state
{5[Ph(1,4-C3T0)2]} to give the polysiloxane-bound complex
X1. For accessibility studies of the reactive centers, X1 was
NMR (13C, 29Si, 31P), IR, EDX, and EXAFS spectroscopy.
the introduction of the concept of an interphase.[11Ϫ14] In-
terphases are systems in which a stationary phase (com-
prised of a polymer, space, and reactive centers) and a mo-
bile component (gas, liquid, or dissolved reactants) penet-
rate each other on a molecular scale without forming a
homogeneous phase. Stationary phases are usually gener-
ated by simultaneous co-condensation of T-silyl-func-
tionalized transition metal complexes with various bifunc-
tionalized alkoxysilanes.[15Ϫ20] This procedure affords the
possibility of modifying materials by controlling the mobil-
ity of the entire polymer, the density, and the distance of
the reactive centers as well as swelling capabilities.
A major problem intrinsic to interphases is that of low
diffusion, which adversely influences the activity of the
catalysts as not all reactive centers are readily accessible for
the substrates. Excellent model systems for accessibility
studies are iridium complexes, which are much more stable
than their corresponding rhodium congeners.
The objective of this work was to study the performance
of organometallic model reactions in interphases. Therefore
the reactive behavior of an iridium(I) complex incorporated
into a stationary phase towards a series of molecules with
different shapes and sizes like oxygen, sulfur dioxide, dicy-
anoethyne, and different halogenated substrates was exam-
ined. The resulting products were characterized by several
spectroscopic methods as well as by EXAFS and EDX.
Introduction
In the last few years polymer-supported catalysts have
evolved into an area of intensive research with the goal of
combining the advantages of homogeneous and heterogen-
eous catalysis.[1Ϫ10] The catalysts are easily separable from
the reaction products and they can be used for several runs,
although frequently with some loss of activity due to metal
leaching. In addition the reactive centers are very often not
well defined, which also causes a decrease of the activity
and selectivity. So far these drawbacks have prevented a
commercial application of heterogenized catalysts. A versat-
ile approach to reduce or even eliminate these problems is
[‡]
Supported Organometallic Complexes, 33. Part 32:
E. Holder, D. Oelkrug, H.-J. Egelhaaf, H. A. Mayer, E. Lindner,
J. Fluorescence, submitted for publication.
[a]
Institut für Anorganische Chemie der Universität,
Auf der Morgenstelle 18, 72076 Tübingen, Germany
Fax: (internat.) ϩ49-(0)7071/295-306
E-mail: ekkehard.lindner@uni-tuebingen.de
[b]
Institut für Angewandte Physik der Universität,
Auf der Morgenstelle 10, 72076 Tübingen, Germany
Fax: (internat.) ϩ49-(0)7071/295-400
E-mail: erich.plies@uni-tuebingen.de
[c]
Institut für Physikalische Chemie der Universität,
Pfaffenwaldring 55, 70569 Stuttgart, Germany
Fax: (internat.) ϩ49-(0)711/685-4443
E-mail: h.bertagnolli@ipc.uni-stuttgart.de
1998
 WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0808Ϫ1998 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 1998Ϫ2006

Sol-Gel Processed Phosphane-Substituted IrI Complexes
FULL PAPER
Results and Discussion
tionalized phosphane ligand 3(T0)[22] was added to an ace-
tonitrile solution of [Ir(µ-Cl)(CO)2]2 (2) to give a light
brown solution of 4(T0) which was subjected to the sol-gel
process directly. A single peak in the 31P{1H} NMR spec-
trum of 4(T0) at δ ϭ 24.7 ppm and one ν(CO) absorption
in the IR spectrum at 1966 cmϪ1 indicated the completeness
of the reaction.[23,24]
Sol-Gel Processing of the Monomeric Iridium(I) Precursor
Complex 4(T0)
The iridium(I) complex 4(T0) was obtained by a modi-
fication of the synthetic pathway of Roberto et al.
(Scheme 1).[21] A stoichiometric amount of the T-silyl-func-
A 1:5 mixture of the iridium complex 4(T0) and of the
co-condensation agent 5[Ph(1,4-C3T0)2][18] was hydrolyzed
and polycondensed in water/THF in the presence of tetra-
butylammonium fluoride (TBAF) as catalyst at room tem-
perature (Scheme 2). The resulting xerogel X1 was isolated
as a pale yellow powder which is rather air stable. Only one
signal, with a chemical shift of δ ϭ 24.4 ppm, is observed
in the 31P CP/MAS NMR spectrum of the polysiloxane-
bound iridium(I) complex X1, in agreement with the spec-
trum of the monomeric complex 4(T0) measured in solution
(Figure 1). To decide whether the phosphanes in X1 are cis
or trans oriented to each other a J-resolved 2D 31P CP/
MAS NMR spectrum according to a phase-cycled spin-
echo-experiment was recorded (Figure 2).[25] The observed
2JP,P coupling constant of approximately 400 Hz is consist-
ent with a trans configuration. In the 13C CP/MAS NMR
spectrum of X1 all main signals stem from the co-condens-
ing moiety. The missing signal for the SiϪOMe function
indicates a high degree of hydrolysis. All silicon atoms in
the polysiloxane matrix are in the direct proximity of pro-
tons, therefore silyl species are detectable by cross polariza-
tion (CP). The signals in the 29Si CP/MAS NMR spectrum
of the copolymer X1 are located in the typical range for T-
silyl functions and their substructures T2 and T3 [δ ϭ Ϫ57.3
Scheme 1
Scheme 2
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E. Lindner et al.
FULL PAPER
(T2), Ϫ65.7 ppm (T3)]. The degree of condensation, which
was determined by commonly used methods,[26,27] is 87%.
Spin-lattice relaxation times of the protons in the rotating
frame (T1ρH) were determined by a direct spin lock-τ-CP
experiment[28] via the 29Si and 31P nuclei. In all cases the
observed decays of the magnetization were monoexponen-
tial. Thus the relaxation mechanism is spin-diffusion con-
trolled and the material can be considered as homogenous.
The formation of domains larger than 1Ϫ2 nm in diameter
is excluded.
Figure 2. J-resolved 2D 31P CP/MAS NMR spectrum of X1
The ν(CO) vibration (1965 cmϪ1) in the IR spectrum of
X1 is similar to that of 4(T0) in solution (Figure 3). The
elemental composition of the stationary phase X1 was de-
termined by EDX (Table 1).
Oxidative Addition Reactions on the Stationary Phase X1
with Hydrogen Chloride, Chlorine, Tetrachloroethane, and
Methyl iodide (13C-Methyl Iodide)
Treatment of the solid X1 with hydrogen chloride or
chlorine (interphase system: solid/gas) led to a color change
from yellow to white and the polymer-anchored iridium
complexes X2 and X3, respectively, were formed quantitat-
ively. The 31P CP/MAS NMR and IR spectra are in full
agreement with the data recorded for the corresponding
monomeric complexes in solution (see Exp. Sect. and Fig-
ure 1 and 3).[29]
In the case of the reaction between X1 and tetrachloroe-
thane in benzene (interphase system: solid/liquid) a mixture
of two different products was obtained. One component
proved to be the meridional trichloroiridium(III) complex
X3, the monomeric congener of which was described in
earlier work by Al-Najjar.[30] Interestingly the second spe-
cies turned out to be complex X2, already isolated from the
reaction between hydrogen chloride and X1. Obviously
after initial oxidative addition of the CϪCl bond both a β-
CϪCl and a β-CϪH elimination take place at room temper-
ature in a competitive reaction path. The 31P CP/MAS
NMR spectrum reveals two resonances at δ ϭ Ϫ3.0 (X2)
and Ϫ18.2 ppm (X3) (Figure 1).[31] An unresolved broad
absorption in the CϵO region between 2030 and 2080 cmϪ1
was found in the IR spectrum of this mixture (Figure 3). A
direct comparison of these results with those of the known
monomeric iridium(III) complexes[29] confirms the adopted
structures depicted in Scheme 3.
Methyl iodide could also be oxidatively added in benzene
to the iridium complex in X1 in the interphase (solid/liquid)
to give the air-stable light brown polymer X4 (Scheme 3).
The carbonyl ligand gives rise to a strong absorption band
at 2042 cmϪ1, which is in accordance with literature values
Figure 1. 31P CP/MAS NMR spectra of the stationary phases
X1ϪX7
2000
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Sol-Gel Processed Phosphane-Substituted IrI Complexes
FULL PAPER
for the corresponding monomeric complex in solution.[32]
Only one resonance is observed in the 31P CP/MAS NMR
of X4 (Figure 1), indicating a complete conversion in the
reaction. If 13C-labeled methyl iodide was used an addi-
tional intense signal was observed in the 13C CP/MAS
NMR spectrum, which is consistent with an iridium-bound
methyl group (Figure 4).
Reactions of the Stationary Phase X1 with Sulfur Dioxide,
Oxygen, and Dicyanoethyne
In the solid/gas and solid/liquid interphase systems the
polysiloxane-bound iridium(I) complex X1 was reacted
with sulfur dioxide, oxygen, and dicyanoethyne to give the
polymeric products X5, X6, and X7, respectively
(Scheme 3). The CϵO stretching vibration in the IR spectra
of these materials confirmed a complete conversion. Ab-
sorptions at 2018, 2008, and 2014 cmϪ1 (Figure 3) were ob-
served, which are shifted to higher wave numbers relative to
X1 (1966 cmϪ1). These spectra were recorded under a sulfur
dioxide (X5) or oxygen (X6) atmosphere. If these gases are
removed, the spectrum of the starting compound X1 ap-
pears again. However, the 31P CP/MAS NMR spectra of
X5 and X6 reveal two 31P resonances (Figure 1). Since the
rotors could not be packed under an oxygen or sulfur diox-
ide atmosphere a reversible reaction took place resulting in
partial formation of the starting material X1. In contrast
to this observation the dicyanoethyneiridium(I) complex X7
shows only one 31P signal at δ ϭ Ϫ3.3 ppm (Figure 1).
These findings are in agreement with literature data[33] for
the monomeric congeners in which oxygen, dicyanoethyne,
and sulfur dioxide are η2-, ηz-, and η1-coordinated, respect-
ively.
EXAFS and EDX Measurements of Selected Stationary
Phases
One of the most powerful methods to obtain interatomic
distances of amorphous materials is extended X-ray absorp-
tion fine structure spectroscopy (EXAFS). The xerogel X4
was chosen as an example to determine the bond lengths
between the metal center and the coordinating atoms of the
ligand. The k3-weighted EXAFS function (see a in Fig-
ure 5) of X4 can be described best by six different atom
shells. The first intensive peak in the corresponding Fourier
transform (see b in Figure 5) is mainly due to the carbon
atoms. Chlorine and phosphorus atoms were found in the
case of the most intense peak, and the third intense peak
belongs to the iodine and oxygen atoms. For the most in-
tense peak of the Fourier transform (see b in Figure 5), two
equivalent phosphorus atoms and one chlorine atom, with
˚
IrϪP and IrϪCl bond lengths of 2.40 and 2.46 A, were
found. These results reveal a good agreement between the
experimental and the calculated functions. A significant im-
provement in the fit of the first intense peak was obtained
if two carbon atoms with IrϪC1 (IrϪCO bond) and IrϪC2
˚
(IrϪCH3) bond lengths of 1.86 and 2.19 A, respectively, are
considered (see b in Figure 5). Additionally, one iodine and
one oxygen atom, with an IrϪI bond length of 2.63 A and
Figure 3. IR spectra of the stationary phases X1ϪX7
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˚
2001

E. Lindner et al.
FULL PAPER
Table 1. Elemental analysis of compounds X1ϪX4 by EDX; hydrogen cannot be measured by X-ray emission spectroscopy therefore the
reference data have been renormalized to exclude hydrogen
Xerogel
Reference data[a]
Composition [%]
EDX[b]
Composition [%]
C
O
Si
P
Cl
Ir
I
C
O
Si
P
Cl
Ir
I
X1
X2
X3
X4
57.54
56.62
55.74
54.63
13.87
13.65
13.43
13.04
15.38
15.13
14.89
14.46
2.83
2.78
2.74
2.66
1.62
3.18
4.70
1.52
8.77
8.63
8.50
8.25
Ϫ
Ϫ
Ϫ
59.33
56.59
58.78
54.55
15.54
11.16
14.58
13.37
13.87
17.77
13.14
14.89
2.60
3.51
3.18
2.97
1.19
2.89
4.76
1.14
7.47
8.08
5.56
8.57
Ϫ
Ϫ
Ϫ
4.50
5.44
[a]
[b]
Calculated from theory. Complete condensation was assumed. Quantified by the ZAF correction procedure.
Scheme 3
˚
an IrϪO bond length of 3.08 A, were detected, leading to
The EDX spectra of compounds X3 and X4 are displayed
an improvement of 7.4 and 18.9% in the fit, respectively. in Figure 6. The Kα lines of carbon, oxygen, silicon, phos-
The interatomic distances of X4 are similar to those in sim- phorus, and chlorine and the Lα line of iridium are clearly
ilar iridium(III) complexes such as [IrCl3(CO)(PPh3)2],[34] visible. The Mα and Mβ lines of iridium are overlapped by
[IrCl(H)(SH)CO(PPh3)2],[35] and [Ir(OClO3)(CH3)(H2O)- the Kα peak of phosphorus. In the case of X4, the L line
[36]
(CO)(PPh3)2]ClO4
(Table 2).
series of iodine also appears in the spectrum. The increasing
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Sol-Gel Processed Phosphane-Substituted IrI Complexes
FULL PAPER
Table 2. EXAFS-determined structural data of X4
[b]
[c]
N[a]
r [A]
σ [A]
˚
˚
IrϪC1 (CO)[d]
IrϪC2 (CH3)[d]
IrϪP[d]
1
1
2
1
1
1
1.86 Ϯ 0.02
2.19 Ϯ 0.02
2.40 Ϯ 0.02
2.46 Ϯ 0.03
2.63 Ϯ 0.03
3.08 Ϯ 0.03
0.050 Ϯ 0.005
0.095 Ϯ 0.010
0.067 Ϯ 0.010
0.097 Ϯ 0.010
0.118 Ϯ 0.012
0.050 Ϯ 0.005
IrϪCl[d]
IrϪI[d]
IrϪO[d]
[a]
[b]
[c]
Coordination number N.
Interatomic distance r.
[d]
DebyeϪWaller factor σ. Absorber backscatterer.
Quantification of the EDX spectra was carried out using
the ZAF correction procedure. However, as this correction
procedure is valid only for flat specimens, and as the xerog-
els exhibit a pronounced morphology (Figure 7), special
care had to be taken to find a locally flat specimen area
larger than the expected electron range, which is certainly
below 10 µm under the present conditions. Other sources of
error, especially in light element analysis, are uncertainties
in fundamental parameters and spectrometer calibration at
X-ray energies below 1 keV. Spectral interference occurring
between iridium and phosphorus can be corrected by peak
deconvolution. Due to its high fluorescence yield, the Au-
Mα line also appears under the Kβ emission of phosphorus.
However, the gold coating can be neglected with respect
to quantification as, owing to its thickness of only 20 nm,
additional absorption effects are not introduced.
Figure 4. 13C CP/MAS NMR spectra of the stationary phase X4
(top: without 13C labeling of the methyl iridium group; bottom:
with 13C labeling of the methyl iridium group)
Despite the numerous sources of error simultaneous
quantification of all the elements present was carried out
content of chlorine in the xerogels X1ϪX3 is evident as the successfully. The elemental analyses by EDX are summar-
intensity of the chlorine K line emission increases in the ized in Table 1 and compared to data obtained from theory.
same direction.
These have been renormalized to exclude hydrogen as a
3
Figure 5. Experimental (dotted line) and calculated (solid line) k χ (k) functions (a) (k range: 2.99Ϫ15.14 AϪ1) and their Fourier trans-
˚
forms (b) for X4 (Ir- L3-edge) (see Table 2 for fit parameter)
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E. Lindner et al.
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Conclusion
For successful catalytic processes in interphases the
polysiloxane-bound reactive centers should be completely
accessible for substrate molecules. Therefore catalytic model
reactions, for example the activation of small and larger
molecules, are of great importance for the better under-
standing of catalytic reactions in interphases. To introduce
reactive centers a phosphaneiridium(I) complex has been
chosen because such a system is suitable for the envisaged
model reactions. For the construction of a mobile station-
ary phase the T-silyl functionalized iridium complex 4(T0)
was co-polycondensed with the bifunctionalized co-con-
densation agent (MeO)3Si(CH2)3C6H4(CH2)3Si(OMe)3
{5[Ph(1,4؊C3T0)2]} which has already been successfully
employed in the rhodium-catalyzed hydroformylation of 1-
hexene. The iridium-containing xerogel X1 was then sub-
jected to various oxidative additions and to the coordina-
tion of an alkyne. It could be unequivocally demonstrated
that the iridium centers in X1 were completely accessible
for a variety of substrates with different shapes and sizes.
The higher cross linkage of the T-silyl bifunctionalized co-
condensation agent in the hybrid polymer matrix does not
exert a disadvantageous effect on the accessibility of the
metal centers. This fact presents a necessary precondition
for a successful catalytic process. With the examples of the
reactions with sulfur dioxide and dioxygen it could be
shown that substrate molecules are also able to leave the
polysiloxane matrix reversibly without any interference.
Most of these model reactions were also carried out with
the corresponding rhodium(I) interphase system. However,
the formed complexes proved to be unstable and partially
decomposed.
Figure 6. Energy-dispersive X-ray spectra of compounds X3 (top)
and X4 (bottom); as shown by comparison of the Cl-Kα emission
line intensities in the inlay, the chlorine content clearly increases
from X1ϪX3; quantification results are summarized in Table 1
Experimental Section
General: IR data were obtained on a Bruker IFS 48 FTϪIR spec-
trometer. CP/MAS solid state NMR spectra were recorded on a
Bruker DSX 200 multinuclear spectrometer equipped with a wide-
bore magnet (field strength 4.7 T). Magic angle spinning was ap-
plied up to 10 kHz (4 mm ZrO2 rotors) and 3Ϫ4 kHz (7 mm ZrO2
rotors). Frequencies and standards: 31P: 81.961 MHz (4.7 T) [85%
H3PO4, NH4H2PO4 (δ ϭ 0.8 ppm) as second standard]; 13C:
50.228 MHz (4.7 T), [TMS, carbonyl resonance of glycine (δ ϭ
176.05 ppm) as second standard]; 29Si: 39.73 MHz (4.7 T), (Q8M8
as second standard). All samples were packed with exclusion of
molecular oxygen. The J-resolved 2D phase-cycled spin-echo-ex-
periment was carried out according to ref.[25] [90° proton pulse
length 3.8 µs, 180° proton pulse length 7.6 µs, contact time Tc 1
ms, recycle delay 1.5 s, time domain (F1) 64, time domain (F2)
2048, number of scans 512]. The cross polarization constants TXH
were determined by variation of the contact time Tc (14Ϫ16 experi-
ments). The proton relaxation times in the rotating frame T1ρΗ
were measured by direct proton spin lock-τ-CP experiments[28] via
31P. The relaxation parameters were obtained using Bruker soft-
ware SIMFIT and WINFIT following the procedure described in
ref.[15]
Figure 7. Scanning electron micrograph of X1
single-electron atom does not emit characteristic X-rays.
Except for the iridium content in xerogel X3 the elemental
analyses support the reference data within the limits of
error with the given samples.
The EXAFS measurements were performed at the IrϪL3-edge at
11215 eV on the beamline X1.1 at the Hamburger Synchrotron-
2004
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Sol-Gel Processed Phosphane-Substituted IrI Complexes
FULL PAPER
strahlungslabor (HASYLAB) at DESY, Hamburg at 20 °C, with a
Si(111) double crystal monochromator under ambient conditions
(5.46 GeV, beam current 120 mA). Data were collected in transmis-
Xerogel X1: In a 100 mL Schlenk-tube 5 mL of the crude solution
of 4(T0) in acetonitrile (441.7 mg, 0.39 mmol) was added to 4 mL
of THF. Subsequently, the co-condensation agent 5[Ph(1,4-C3T0)2]
sion mode with ion chambers. Energy calibration was monitored (784.9 mg, 195 mmol) was reacted with the above-mentioned mix-
with 20 µm thick platinum metal foil at the L3-edge at 11564 eV. ture in the presence of 1 mL of water and 0.1 mL of a 0.1  solu-
All measurements were performed under an inert gas atmosphere.
tion of tetrabutylammonium fluoride (TBAF) in THF as the cata-
The samples were prepared from a mixture of X4 and polyethylene. lyst. Stirring overnight afforded a light yellow gel. The liquid con-
Data were analyzed with a program package specially developed
for the requirements of amorphous samples.[37] The program
AUTOBK of the University of Washington[38] was used for back-
ground removal, and the program EXCURV92[39] was used for the
evaluation of the XAFS function. The resulting EXAFS function
was weighted with k3. Data analysis in k space was performed ac-
cording to the curved-wave multiple-scattering formalism of the
program EXCURV92. The mean free path of the scattered electrons
was calculated from the imaginary part of the potential (VPI was
set to Ϫ4.00), the amplitude reduction factor AFAC was fixed at
0.8, and an overall energy shift ∆E0 was introduced to fit the data.
In the fitting procedure the intermolecular coordination numbers
were varied and the intramolecular coordination numbers were
fixed according to the known values of the ligands around the iri-
dium atom of X4.
stituents were separated from the crude gel by filtration (P3) and
the product was washed three times each with 10 mL of THF and
10 mL of n-hexane. Finally the xerogel was dried under vacuum for
4 h to give a yellow powder. Yield: 895.1 mg. 13C CP/MAS NMR:
δ ϭ 139.3, 128.3 (C-phenyl, backbone and ligand), 37.9, 25.2, 12.9
(CH2, backbone and spacer) ppm. 29Si CP/MAS NMR: δ ϭ Ϫ56.6
(T2), Ϫ65.7 (T3) ppm. 31P CP/MAS NMR: δ ϭ 24.4 ppm. IR
(KBr): ν˜ ϭ 1965 (CϵO) cmϪ1
.
General Procedure for the Synthesis of the Xerogels X2, X3, X5, and
X6 (Gas/Solid Interphases): X1 (100.0 mg) was placed in a 100 mL
Schlenk tube with a magnetic stirring bar. Subsequently argon was
replaced by the respective gaseous reactants at room temperature.
After removal of excess reactant by argon the xerogels X2, X3, X5,
and X6 were obtained. In the case of the polymers X2 and X3 the
yields were quantitative.
Scanning electron microscopy[40] was performed on an XL 30 scan-
ning electron microscope from Philips equipped with an DX-4 en-
ergy dispersive X-ray detection system by EDAX. This consists of
a liquid-nitrogen-cooled lithium-drifted silicon detector with an
active area of 10 mm2 and the eDXi 2.11 software package. The
detector resolution is 149 eV at Mn-Kα (5.984 keV) and the sample-
detector distance is 50 mm in the present system. The sample pow-
der was placed on a commercial specimen stub covered with an
adhesive tab and subsequently covered with a sputtered 20 nm gold
layer to ensure conductivity. The primary beam energy was 20 keV
during all investigations. A probe current of 192 pA was applied
for recording electron micrographs, whereas X-ray emission spectra
were acquired under spot illumination applying a probe current of
569 pA for 400 live seconds (dead time approx. 33%). Measure-
ments were repeated several times at various specimen positions to
ensure reproducibility. Quantification of the X-ray spectra was car-
ried out employing the ZAF correction procedure[41Ϫ43] after sub-
traction of the Bremsstrahlung background.
X2: X1 was treated with hydrogen chloride. Yield: 101.2 mg. 31P
CP/MAS NMR: δ ϭ Ϫ3.2 ppm. IR (KBr): ν˜ ϭ 2043 (CϵO) cmϪ1
.
X3: X1 was treated with chlorine. Yield: 102.1 mg. 31P CP/MAS
NMR: δ ϭ Ϫ20.4 ppm. IR (KBr): ν˜ ϭ 2071 (CϵO) cmϪ1
.
X5: X1 was treated with sulfur dioxide. Yield: 101.6 mg. 31P CP/
MAS NMR: δ ϭ 23.9 (X1), 7.8 (X5) ppm. IR (KBr): ν˜ ϭ 2018
(CϵO) cmϪ1
.
X6: X1 was treated with oxygen. Yield: 101.6 mg. 31P CP/MAS
NMR: δ ϭ 24.1 (X1), 3.0 (X6) ppm. IR (KBr): ν˜ ϭ 2008 (CϵO)
cmϪ1
.
General Procedure for the Synthesis of the Xerogels X4 and X7 and
Treatment of X1 with Tetrachloroethane (Liquid/Solid Interphases):
A suspension of X1 (100.0 mg) in 5 mL of benzene was treated with
0.5 mL of methyl iodide, 13CH3I, dicyanoethyne, or tetrachloro-
ethane, and the mixture stirred for 24 h at ambient temperature.
The liquid constituents were removed by filtration (P3) and, after
drying under vacuum, the respective xerogels were obtained.
All reactions and manipulations were carried out under argon with
usual Schlenk techniques. All solvents were distilled from sodium
benzophenone or calcium hydride. H2O was distilled under inert
gas prior to use. All solvents and reagents were stored under argon.
[IrCl(COE)2]2 was purchased from Aldrich, all other chemicals
were bought from Fluka. The T-silyl functionalized triphenylpho-
shine 3(T0) and dicyanoethyne were prepared according to literat-
ure methods.[22,44]
X4: X1 was reacted with CH3I or 13CH3I. Yield: 96.4 mg (96.3 mg
for 13CH3I). 13C CP/MAS NMR: δ ϭ 139.1 (139.4*), 128.6 (128.3*)
(C-phenyl, backbone and ligand), 50.1 (50.1*) (OCH3), 37.6
(38.2*), 24.5 (24.9*), 12.5 (12.7*) (CH2, backbone and spacer),
Ϫ5.1 (13CH3-Ir) ppm. The asterisk indicates data for the 13C la-
beled compound. 31P CP/MAS NMR: δ ϭ Ϫ20.2 ppm. IR (KBr):
ν˜ ϭ 2042 (CϵO) cmϪ1
.
Carbonylchlorobis[diphenyl{4-[4-(trimethoxysilyl)butyl]-
phenyl}phosphane-κP]iridium(I) [4(T0)]: In a three-necked flask
[IrCl(COE)2]2 (350.0 mg, 0.390 mmol) was suspended in 10 mL of
acetonitrile. After 10 min the argon was replaced by carbon monox-
ide. Undissolved [IrCl(COE)2]2 disappeared immediately, and a yel-
low solution was obtained, which indicated the formation of
[IrCl(CO)2]2. After 10 min under an atmosphere of CO the T-silyl
functionalized triphenylphosphane 3(T0) (684.3 mg, 156 mmol) was
added. The color of the solution changed to brown yellow. Accord-
ing to the 31P{1H} NMR and IR spectra the reaction was finished
after 20 min. The complex 4(T0) was sol-gel processed without fur-
ther purification. 31P{1H} NMR (C6D6): δ ϭ 24.7 (s) ppm. IR
X6: X1 was reacted with dicyanoethyne. Yield: 95.8 mg. 31P CP/
MAS NMR: δ ϭ Ϫ3.3 ppm. IR (KBr): ν˜ ϭ 2192 (CϵN), 2014
(CϵO) cmϪ1
.
Behavior of X1 Toward Tetrachloroethane: X1 was reacted with
tetrachloroethane. Yield: 96.7. 31P CP/MAS NMR: δ ϭ Ϫ3.5 (X2),
Ϫ18.3 (X3) ppm. IR (KBr): ν˜ ϭ 2070, 2043 (CϵO) cmϪ1
.
Acknowledgments
This work was supported by the Deutsche Forschungsgemeinschaft
(KBr): ν˜ ϭ 1966 (CϵO) cmϪ1
.
(Graduiertenkolleg ‘‘Chemie in Interphasen’’, Grant No. 441/2,
Eur. J. Inorg. Chem. 2002, 1998Ϫ2006
2005

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[I01507]
2006
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