Synthesis, structure, immobilization and solid-state NMR of new dppp- and tripod-type chelate linkers

Article abstract of DOI:10.1016/j.jorganchem.2005.04.021

Chelating phosphines incorporating ethoxysilane functions for immobilizations have been synthesized and fully characterized. (EtO)Si(CH ₂PPh₂)₃, (EtO)₂Si(CH ₂PPh₂)₂, and Si(CH₂PPh ₂)₄ could be prepared in high yields from cheap starting materials. The ethoxysilanes, as well as a Pd complex thereof have been characterized by X-ray structures, and immobilized on silica. The success of the immobilization was proved by ³¹P solid-state NMR of the dry materials and of the suspensions. Two representative chelate metal complexes, (EtO)₂Si(CH₂PPh₂)₂PdCl₂ and (EtO)Si(CH₂PPh₂)₃W(CO)₃ have been synthesized, characterized and immobilized.

Full text of DOI:10.1016/j.jorganchem.2005.04.021

Journal of Organometallic Chemistry 690 (2005) 3383–3389
www.elsevier.com/locate/jorganchem
Synthesis, structure, immobilization and solid-state NMR of new
dppp- and tripod-type chelate linkers
*
Mona Bogza, Thomas Oeser, Janet Blumel
¨
Department of Organic Chemistry, Organisch-Chemisches Institut der Universita¨t Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
Received 25 January 2005; revised 8 April 2005; accepted 11 April 2005
Available online 2 June 2005
Abstract
Chelating phosphines incorporating ethoxysilane functions for immobilizations have been synthesized and fully characterized.
(EtO)Si(CH2PPh2)3, (EtO)2Si(CH2PPh2)2, and Si(CH2PPh2)4 could be prepared in high yields from cheap starting materials. The
ethoxysilanes, as well as a Pd complex thereof have been characterized by X-ray structures, and immobilized on silica. The success
of the immobilization was proved by 31P solid-state NMR of the dry materials and of the suspensions. Two representative chelate
metal complexes, (EtO)2Si(CH2PPh2)2PdCl2 and (EtO)Si(CH2PPh2)3W(CO)3 have been synthesized, characterized and immobilized.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ethoxysilanes; Chelating phosphines; Solid-state NMR; Immobilization; Linkers; Pd catalyst
1. Introduction
as well as their reactivity with oxidic surfaces, and their
structural nature.
The success of immobilized species is crucially depen-
dent on the behavior of the linker, no matter whether
they are applied for combinatorial chemistry [1], solid-
phase synthesis [2], chromatography [3], or catalysis
[4]. We, and also many other groups [5] have striven
to improve the recyclability and lifetime of immobilized
catalysts by anchoring them on oxidic supports via link-
ers [6–8]. For such surface chemistry solid-state NMR
spectroscopy [9] proves to be an indispensable and pow-
erful analytical method. For our systems we recently
optimized the cross polarization (CP) process at high
magic angle spinning (MAS) frequencies [10] for getting
better signal to noise ratios (S/N), and implemented sta-
tionary [11a,11b] and HR-MAS suspension NMR spec-
troscopy [11c] to study the mobilities of surface species,
There with we could clarify the reaction of the popu-
lar Ph2P(CH2)3Si(OEt)3 or of chelating phosphines with
the silica surface [6–8,12,13]. The solvent turned out to
be important for the immobilization process [14], while
the strongest bonding takes place with silica [11b]. Fur-
thermore, metal complexes with two monodentate link-
ers are not necessarily bound in a chelating manner [15],
making them vulnerable to leaching [8,11]. This problem
can for example be solved by using chelating linkers that
prolong the lifetimes of the catalysts substantially [6–
8,11c,12]. Surprisingly, chelate phosphine linkers incor-
porating ethoxysilane groups for immobilizations on
silica are still rare [6,7,12,17], and many, e.g. bisphosph-
inoamine linkers [11c], even decompose during the
immobilization process or form phosphonium salts as
side-products [11c,16]. In earlier studies on Ni and Rh
complexes we showed that dppp-type linkers gave the
best immobilized catalysts [6–8], while the length of
the spacer did not display a visible effect. However, rigid
spacers that reduced the contact of the metal complex
*
Corresponding author. Tel.: +49 6221 548470; fax: +49 6221
544904.
E-mail address: J.Bluemel@urz.uni-heidelberg.de (J. Blumel).
¨
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.04.021

3384
M. Bogza et al. / Journal of Organometallic Chemistry 690 (2005) 3383–3389
with the surface led to more active catalysts. Therefore,
in this work, we will present a new class of rigid bi- and
tridentate dppp-type linkers incorporating the ethoxysi-
lane group in the center of the chelate backbone. These
linkers, in contrast to previous ones [12] are symmetric,
which is desirable from an analytical point of view, and
it will be demonstrated that they can coordinate and an-
chor metal complexes in a clean and well-defined
manner.
Dppp-type ligands with heteroatoms in the center of
the backbone are enjoying growing interest, because
they allow the fine-tuning of their electronic properties.
In the case of the borate ligands [Ph2B(CH2PPh2)2]À for
example, even a negative charge can be introduced [18].
Although dppp-type phosphine chelate ligands with a
silicon atom in the center, such as Ph2Si(CH2PPh2)2 pro-
vide useful neutral versions of electron-rich ligands, and
are known to produce, e.g., highly active Wilkinson cat-
alysts for hydrogenations [18], to the best of our knowl-
edge there are no versions incorporating ethoxysilane
groups for immobilization.
The same accounts for tripodal phosphines. For
example, the silicon and tin versions of triphos, Me-
Si(CH2PPh2)3 and MeSn(CH2PPh2)3, are known, and
their Rh(I) and Ru(II) coordination chemistry has been
explored [19]. Recently, in addition the tridentate ligand
tBuSi(CH2PMe2)3, and the reactivity of vanadium com-
plexes thereof, has been studied [20], but again no alk-
oxy derivative is known.
For later comparisons of our immobilized catalysts
with their homogeneous versions, we also sought to syn-
thesize a dppp-type ligand with Si in the center, but
without ethoxy groups, namely Si(CH2PPh2)4. The lat-
ter can function both as bi- and tridentate ligand, and
will later also allow the study of cooperative effects. Fur-
thermore, it might be useful as a building block for den-
drimers, as the known Si(CH2CH2PPh2)4 already is
[21,22].
1.0:0.2:1.1, with traces of (EtO)3SiCl, could easily
be separated by distillation with a vigreux column at
ambient pressure. So, 1 has been obtained in analytically
pure form in about 61% yield with respect to SiCl4
(Scheme 1).
The new ligands, with the names we suggest to be Si-
bisphos (2), Sitriphos (3) and Quadruphos (4), were syn-
thesized according to the route given in Scheme 2, with
typical, unoptimized yields of 84%, 82%, and 66%,
respectively. The lithium salt Ph2PCH2Li(TMEDA) (5)
was obtained as described in the literature [23]. It should
be mentioned that an attempt to obtain 2 along with
Si(OEt)4 by disproportionation of Ph2PCH2Si(OEt)3
[17] using CsF, as successfully applied to HSi(OEt)3
[24], unfortunately did not work.
The NMR signal assignments of all the compounds in
this work have been done by standard 1D and 2D tech-
niques, and by comparison with previously described
linkers with Ph2PR moieties [6a,11c,12,17]. The triplet
and quartet of the 29Si NMR signals of 2 and 3, respec-
tively, are in nice agreement with the multiplicities ex-
pected for two and three equivalent 31P nuclei in the
alpha position to silicon. Taking a look at the 13C
NMR spectra of 2–4, 6, and 7, the most interesting fea-
ture is found for the aryl carbon signals, many of which
display ‘‘virtual 31P couplings’’ [25]. This is confirmed by
various 1H and 31P decoupling experiments, in which the
corresponding aryl carbon signals appear equally cou-
pled to all phosphorus nuclei within the molecules [25].
Although linkers incorporating ethoxysilane groups
are usually viscous liquids and thus hard to crystallize,
compounds 2 and 3 do so readily, and they could be
subjected to X-ray analyses (Figs. 1 and 2).
In both cases, as expected, the substituents at the Si
center are arranged in a tetrahedral manner, and the
diphenylphosphine moieties assume the positions im-
posed on them by the packing demands in the crystals.
Although the ligands, out of the ensembles of confor-
mation that one would expect to be populated in solu-
2. Results and discussion
Ph2P
Si(OEt)2
The starting material for our synthesis, (EtO)2SiCl2,
(1), could not be obtained by comproportionation of
(EtO)4Si with SiCl4, because the resulting mixture, due
to similar boiling points of the products, turned out to
be inseparable. Therefore, we synthesized 1 by stirring
equimolar amounts of SiCl4 and Me2Si(OEt)2 in a sealed
tube for 5 h at 165 ꢁC (Scheme 1). The resulting mixture
of 1, EtOSiCl3, and Me2SiCl2, in a typical ratio of
a
Ph2P
Ph2P
2
(EtO)2SiCl2
b
1
Si(OEt)
Ph2P
Ph2P
3
Ph2P
Ph2P
PPh2
PPh2
c
Si
SiCl4
4
SiCl4 + Me2Si(OEt)2 → (EtO)2SiCl2 + Me2SiCl2
Scheme 2. Synthesis of the phosphine ligands 2, 3, and 4 (pentane,
RT): a: 2 equivalents of Ph2PCH2Li(TMEDA) (5) [23], 1 h; b: 3
equivalents of 5, 4 h; c: 4 equivalents of 5,1 h, pentane.
1
Scheme 1. Synthesis of (EtO)2SiCl2.

M. Bogza et al. / Journal of Organometallic Chemistry 690 (2005) 3383–3389
3385
Ph2P
PPh2
SiO2
2
Si
2i
O
O
a
PdCl2
PPh2
PdCl2
Ph2P
SiO2
Ph2P
PPh2
Si
Fig. 1. Crystal structure of 2.
6i
Si(OEt)2
O
O
6
Scheme 3. Synthesis of the molecular and immobilized species 2i, 6
and 6i. a: PdCl2(NCPh)2.
Ph2P PPh2
PPh2
SiO
2
3
Si
3i
O
W(CO)
hv
6
W(CO)3
W(CO)3
Ph2P PPh2
Ph2P PPh2
PPh2
PPh2
SiO
2
Si
Fig. 2. Crystal structure of 3.
Si
7
O
7i
OEt
tion, crystallize in forms that are not preorganized for
coordination, they readily bind in a chelating, not in a
bridging manner, and provide only well-defined mono-
nuclear complexes. This coordination preference of li-
gands 2 and 3 could be demonstrated by transforming
them into the Pd and W complexes 6 and 7 (Schemes
3 and 4). The complexation proceeds smoothly, and
the ligands do not have to be recrystallized prior to
reacting them with the proper metal precursors. As their
data show, both ligands coordinate in the desired bi-
and tridentate manner without forming dinuclear
bridged species or involving the ethoxysilane groups.
For 6 this is additionally proven by an X-ray analysis
(Fig. 3), which shows that ligand 2 readily accommo-
dates the square planar coordination at the Pd center.
The phenyl groups are arranged in a way to make space
for the Cl atoms, while the Si atom deviates about
Scheme 4. Synthesis of the molecular and immobilized species 3i, 7
and 7i.
˚
0.89 A perpendicular out of the least squares plane de-
fined by the Pd(PC)2 fragment. Secondary interactions
of the ethoxy oxygen atoms with the metal center obvi-
ously do not take place.
Fig. 3. Crystal structure of the palladium complex 6. The cocrystal-
lized acetone solvent molecule is not shown for clarity.

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M. Bogza et al. / Journal of Organometallic Chemistry 690 (2005) 3383–3389
Due to the rigid geometry of the linkers, as well as the
steric demand of the phenyl substituents at the phos-
phine moieties the ligands should protect immobilized
metal complexes from each other, as well as from the sil-
ica surface, thus preventing their premature deactivation
and leading to recyclable catalysts with longer lifetimes.
This option will be explored in our future work, along
with potential cooperative effects in homogeneous cata-
lysts derived from 4.
*
*
*
*
4. Experimental
All reactions were carried out in Schlenk flasks under
purified nitrogen. The solvents were dried and distilled
according to standard procedures prior to use. Support
material: Silica gel 40 (Merck, specific surface area
ppm
50
0
-50
-100
Fig. 4. 31P CP/MAS (top, 4 kHz) and 31P suspension HR MAS
(bottom, 2 kHz, in toluene as the suspension medium) spectra of 3i on
silica. Asterisks denote rotational sidebands. For details of the
measurements see [10] and [11c].
2
˚
750 m /g, average pore diameter 40 A, particle size
0.063–0.2 mm). The solution NMR spectra were re-
corded on routine Bruker spectrometers at field
strengths corresponding to 250, 300, and 500 MHz.
The solid-state NMR spectra were recorded on a fully
digital Bruker Avance 400 NMR spectrometer equipped
with a 4 mm MAS probehead. This probehead was used
for both, classical and suspension MAS measurements.
For CP/MAS parameters see [10], for suspension HR-
MAS measurement conditions see [11c]. The signal
assignments are based on comparisons with previous
phosphine linkers [6a,12], 31P-decoupled, and 2D corre-
lation spectra.
The linkers 2 and 3 can be immobilized on silica in a
clean and well-defined manner, giving 2i and 3i. The sur-
face coverages are in the typical range [6–8,10–14], for
example 63 mg (0.092 mmol) of 3 are immobilized on
1 g of silica. The 31P CP/MAS spectra show no signals
of ligand destruction [11c], phosphine oxide [16a] or
phosphonium salts [16b], which often occur as side
products in the cases of other linkers. Furthermore, they
are strongly bound in a covalent manner, and after thor-
ough washing do not show leaching from the support.
Fig. 4, for example, shows the 31P CP/MAS spectrum
of 3i on silica at 4 kHz rotational speed (top spectrum).
The halfwidth of the CP/MAS signal is about 800 Hz.
The suspension HR MAS spectrum of 3i in toluene gives
a much narrower line with a halfwidth of merely 335 Hz
even at the low spinning frequency of 2 kHz [11c]. Thus,
any phosphonium- or phosphine oxide-type side-prod-
ucts from the immobilization would not escape our
attention.
Since the ethoxysilane groups are not involved in the
coordination of the metal complexes 6 and 7, they can
function as the usual anchors when immobilizing these
on silica as 6i and 7i (Scheme 3 and 4). The clean and
well-defined immobilization is again proven by 31P CP/
MAS NMR, which demonstrates the absence of any
uncomplexed phosphines, as well as other unwanted
species (see above). Therefore, we conclude that the link-
ers 2 and 3 are ready to be applied for example as metal
scavengers, or linkers for immobilized catalysts.
4.1. (EtO)2SiCl2 (1)
SiCl4 (8.00 g, 47.09 mmol) was combined with 6.98 g
(47.09 mmol) of (CH3)2Si(OEt)2, and stirred in a sealed
tube for 5 h at 165 ꢁC. After distillation with a standard
vigreux column (length 16 cm, diameter 1 cm) at ambi-
ent pressure, 5.4 g (28.55 mmol) of 1 could be collected
at a bath temperature range of 150–160 ꢁC, correspond-
ing to a yield of 60.6%. As a minor impurity (EtO)3SiCl
could occur in up to 5%.
4.2. (EtO)2Si(CH2PPh2)2 (2)
Ph2PCH2Li(TMEDA) (5) (2.34 g, 7.26 mmol) was
suspended in 20 ml of pentane and combined with
0.64 g (3.39 mmol) of (EtO)2SiCl2 (1) dissolved in
10 ml of pentane. After stirring the reaction mixture
for 1 h, it was filtered, and the solvent was partially re-
moved in vacuo. Ligand 2 was obtained in 84.4% yield
(1.48 g, 2.86 mmol) as a colorless powder that could be
1
3. Conclusion
recrystallized from hot pentane. Mp 69 ꢁC. H NMR
(acetone-d6,
500.1 MHz):
d
7.43
(t,
broad,
3J(P,H) = 7.4 Hz, 3J(H,H) = 7.4 Hz, 8H, Ho), 7.32–
A new type of linker for immobilization of metal
complexes on oxidic supports has been described and
fully characterized, including their X-ray structures.
3
7.28 (m, 12H, Hm, Hp), 3.63 (q, 4H, J(H,H) = 7.0 Hz,
OCH2), 1.36 (s, broad, 4H, PCH2), 1.01 (t,

M. Bogza et al. / Journal of Organometallic Chemistry 690 (2005) 3383–3389
3387
3J(H,H) = 7.0 Hz, 6H, CH3). 13C NMR (acetone-d6,
125.8 MHz):
142.71 (dd, 1J(P,C) = 17.0 Hz,
2.3 Hz, OCH2), 18.95 (s, CH3), 15.35 (dt,
3
d
1J(P,C) = 32.2 Hz, J(P,C) = 4.0 Hz, PCH2). 31P NMR
5J(P,C) = 1.7 Hz, Ci), 134.02 (dd, 2J(P,C) = 20.8 Hz,
6J(P,C) = 0.6 Hz, Co), 129.80 (s, Cp), 129.69 (virtual
m, distance of outer lines: J(P,C) = 10.7 Hz, Cm),
59.72 (t, 4J(P,C) = 1.9 Hz, OCH2), 19.11 (s, CH3),
(acetone-d6, 121.5 MHz) d À23.49. 29Si NMR (C6D6,
99.3 MHz) d 7.29 (q, 2J(P,Si) = 15.3 Hz). HR-MS
(FAB) m/z (%): 671.2217 ([M + H]+, 33.8), calc.
671.2212; 593.1703 ([M+H-C6H5]+, 49.2), calc.
593.1742. Elemental Anal. Calc.: C, 73.41; H, 6.16; P,
13.85. Found: C, 73.53; H, 6.19; P, 13.76. 31P CP/
MAS of polycrystalline 3: À15.3/À26.9/À46.2. 31P CP/
MAS of 3i: d À25.04.
1
3
13.76 (dd, J(P,C) = 31.6 Hz, J(P,C) = 3.2 Hz, PCH2).
31P NMR (acetone-d6, 202.5 MHz) d À23.29. 29Si
NMR (C6D6, 99.3 MHz)
d
À15.46 (t, 2J(P,Si) =
15.4 Hz). HR-MS (FAB) m/z (%): 517.1855
([M + H]+, 19.5), calc. 517.1882; 471.1486 ([M À OEt]+,
4.16), calc. 471.1463. Elemental Anal. Calc.: C, 69.75;
H, 6.63; P, 11.99. Found: C, 69.78; H, 6.71; P, 11.92.
31P CP/MAS of polycrystalline 2: À22.9/À24.1. 31P
CP/MAS of 2i: d À25.38.
X-ray data for 3: C41H41OP3Si, colorless crystal
(irregular), dimensions 0.26 · 0.22 · 0.08 mm3, crystal
ꢀ
system triclinic, space group P1, Z = 2, a = 11.2457(8)
˚
˚
˚
A, b = 12.1789(9) A, c = 14.528(1) A, a = 81.112(2)ꢁ,
3
˚
b = 80.782(1)ꢁ, c = 67.705(1)ꢁ, V = 1807.7(2) A ,
X-ray data for 2: C30H34O2P2Si, colorless crystal
(irregular plate), dimensions 0.28 · 0.20 · 0.05 mm3,
crystal system monoclinic, space group P21/n, Z = 4,
q = 1.232 g/cm3, T = 200(2) K, hmax = 28.31ꢁ, radiation
˚
Mo Ka, k = 0.71073 A, 0.3ꢁ x-scans with CCD area
detector, 18531 reflections measured, 8765 unique
(R(int) = 0.029), 6989 observed (I > 2r(I)), intensities
were corrected for Lorentz and polarization effects, an
empirical absorption correction was applied using SAD-
ABS [26] based on the Laue symmetry of the reciprocal
space, l = 0.23 mmÀ1, Tmin = 0.94, Tmax = 0.98, struc-
ture solved by direct methods and refined against F2
with a full-matrix least-squares algorithm using the
SHELXTL (6.12) software package [27], 570 parameters re-
fined, the terminal carbon atom at the ethoxy group is
disordered over two positions (55:45%), hydrogen atoms
at disorder and neighbouring positions were treated
using appropriate riding models all other HÕs were re-
fined isotropically, goodness-of-fit 1.10 for observed
reflections, final residual values R1(F) = 0.056,
˚
˚
˚
˚
a = 14.572(1) A, b = 12.183(1) A, c = 15.963(2) A,
b = 104.353(2)ꢁ, V = 2745.5(5) A , q = 1.250 g/cm3,
3
T = 100(2) K,
hmax = 26.37ꢁ, radiation Mo Ka,
˚
k = 0.71073 A, 0.3ꢁ x-scans with CCD area detector,
covering a whole sphere in reciprocal space, 24093
reflections measured, 5581 unique (R(int) = 0.055),
4630 observed (I > 2r(I)), intensities were corrected
for Lorentz and polarization effects, an empirical
absorption correction was applied using SADABS [26]
based on the Laue symmetry of the reciprocal space,
l = 0.23 mmÀ1
,
Tmin = 0.94, Tmax = 0.99, structure
solved by direct methods and refined against F2 with
a full-matrix least-squares algorithm using the SHELXTL
(6.12) software package [27], 452 parameters refined,
all hydrogen atoms were refined isotropically, good-
ness-of-fit 1.09 for observed reflections, final residual
values R1(F) = 0.050, wR(F2) = 0.106 for observed
reflections, residual electron density À0.30 to
wR(F2) = 0.125 for observed Àr3eflections, residual elec-
˚
tron density À0.33 to 0.55 eA
.
4.4. Si(CH2PPh2)4 (4)
À3
˚
0.58 eA
.
Ph2PCH2Li(TMEDA) (1.76 g, 5.44 mmol) was dis-
solved in a mixture of 10 ml pentane and 5 ml THF,
and subsequently treated with SiCl4 (0.23 g, 1.36 mmol).
After stirring the reaction mixture for 2 h at RT, the
resulting colorless precipitate was filtered, washed with
pentane, and dried in vacuo. Compound 4 was thus ob-
tained as a colorless powder in a yield of 64.5% (0.74 g,
0.89 mmol). Mp 157 ꢁC. 1H NMR (CDCl3, 300.1 MHz):
d 7.23 (m, broad, 40H, phenyl-H), 1.01 (s, 8H). 13C
4.3. (EtO)Si(CH2PPh2)3 (3)
Ph2PCH2Li(TMEDA) (5) (3.02 g, 9.37 mmol) was
suspended in 20 ml of pentane and combined with
0.56 g (2.98 mmol) of (EtO)2SiCl2 (1), dissolved in
10 ml of pentane. After stirring the reaction mixture
for 4 h, the colorless precipitate was collected on a frit,
and 1.65 g (2.45 mmol) of 3 could be extracted in
82.2% yield as a colorless powder with toluene, and sub-
sequently dried in vacuo. Mp 99 ꢁC. 1H NMR (acetone-
d6, 500.1 MHz): d 7.36–7.32 (m, broad, 12H, Ho), 7.31–
NMR (CDCl3, 75.5 MHz):
d 140.78 (d, broad,
1J(P,C) = 14.2 Hz, Ci), 132.62 (d, 2J(P,C) = 20.9 Hz,
Co), 128.34 (s, Cp), 128.20 (virtual t, distance of outer
lines: J(P,C) = 6.9 Hz, Cm), 12.26 (d, broad,
1J(P,C) = 32.6 Hz, PCH2). 31P NMR (CDCl3,
121.5 MHz) d À23.96. 29Si NMR (CDCl3, 99.3 MHz):
d 2.68 (quin, 2J(P,Si) = 15.8 Hz). HR-MS (FAB) m/z
(%): 825.2585 ([M + H]+, 54.8), calc. 825.2549;
747.2132 ([M À C6H5]+, 100.0), calc. 747.2084. 31P CP/
MAS of polycrystalline 4: À29.6.
3
7.28 (m, 18H, Hm, Hp), 3.42 (q, J(H,H) = 7.0 Hz, 2H,
OCH2), 1.28 (s, broad, 6H, PCH2), 0.82 (t,
3J(H,H) = 7.0 Hz, 3H, CH3). 13C NMR (acetone-d6,
1
125.8 MHz): d 142.57 (d, J(P,C) = 17.3 Hz, Ci), 133.97
(virtual dd, distance of outer lines: J(P,C) = 23.2 Hz,
Co), 129.82 (s, Cp), 129.71 (virtual m, distance of
4
outer lines: J(P,C) = 14.5 Hz, Cm), 60.20 (q, J(P,C) =

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M. Bogza et al. / Journal of Organometallic Chemistry 690 (2005) 3383–3389
4.5. [(EtO)2Si(CH2PPh2)2]PdCl2 (6)
and then filtered to remove residual W(CO)6. After re-
moval of the solvent in vacuo 20 ml of toluene was
added. Complex 7 could be obtained in 63.8% yield
(192 mg, 0.20 mmol) as a pale yellow powder after
adding 30 ml of pentane, washing the precipitate
with pentane, and drying it in vacuo. 1H NMR
(CDCl3, 500.1 MHz): d 7.42 (t, broad, 3J(P,H) =
To a solution of (PhCN)2PdCl2 (60 mg, 0.16 mmol)
in toluene (8 ml), 82 mg (0.16 mmol) of 2 was added in
a dropwise manner. After stirring the mixture for 3 h
at RT, about 80% of the solvent was removed and
20 ml of pentane was added. Complex 6 precipitated
as a colorless powder, which was collected on a frit,
washed with pentane and dried in vacuo to give 94 mg
(0.14 mmol) of material, corresponding to a yield of
3
3J(H,H) = 7.5 Hz, 12H, Ho), 7.25 (t, J(H,H) = 7.0 Hz,
3
6H, Hp), 7.16 (t, J(H,H) = 7.0 Hz, 12H, Hm), 3.70 (q,
3J(H,H) = 7.0 Hz, 2H, OCH2), 1.78 (d, 2J(P,H) =
7.0 Hz, 6H, PCH2), 1.20 (t, 3J(H,H) = 7.0 Hz, 3H,
CH3). 13C NMR (CDCl3, 125.8 MHz): d 211.50 (s,
1
85.3%. H NMR (acetone-d6, 300.1 MHz): d 7.84 (dd,
3J(P,H) = 12.0 Hz, 3J(H,H) = 6.0 Hz, 8H, Ho), 7.51–
3
7.48 (m, 12H, Hm, Hp), 3.49 (q, 4H, J(H,H) = 7.0 Hz,
1
CO), 139.21 (d, J(P,C) = 40.2 Hz, Ci), 131.77 (virtual
2
OCH2), 1.87 (dd, J(P,H) = 15.6 Hz, J(P,H) = 5.7 Hz,
4
m, distance of outer lines: J(P,C) = 13.0 Hz, Co),
129.06 (s, Cp), 128.19 (virtual m, distance of outer lines:
J(P,C) = 9.5 Hz, Cm), 59.97 (s, OCH2), 18.18 (s, CH3),
11.89 (s, broad, PCH2). 31P NMR (CDCl3,
202.5 MHz) d À4.59 (s with satellites, 1J(W,C) =
219.3 Hz). HR-MS (FAB) m/z (%): 938.1448 ([M]+,
100.0), calc. 938.1496; 910.1398 ([M À CO]+, 36.1), calc.
3
4H, PCH2), 0.94 (t, J(H,H) = 7.0 Hz, 6H, CH3). 13C
NMR (acetone-d6, 75.5 MHz): d 135.36 (virtual m, dis-
tance of outer lines: J(P,C) = 14.4 Hz, Co), 134.37 (d,
1J(P,C) = 57.6 Hz, Ci), 132.44 (virtual t, distance of out-
er lines: J(P,C) = 2.6 Hz, Cp), 129.61 (virtual m, distance
of outer lines: J(P,C) = 14.6 Hz, Cm), 59.92 (s, OCH2),
1
18.87 (s, CH3), 13.64 (d, J(P,C) = 24.5 Hz, PCH2). 31P
910.1547; 833.1011 ([M À CO À C6H5]+, 16.51), calc.
À1
~
NMR (acetone-d6, 121.5 MHz)
d
23.40. HR-MS
833.1156. IR (KBr): m 1929; 1833 cm
.
UV/Vis
(FAB) m/z (%): 692.0245 ([M]+, 2.0), calc. 692.0215;
659.0538 ([M À Cl]+, 100.0), calc. 659.0531. 31P CP/
MAS of 6i: d 24.86.
(CH2Cl2): kmax (e) 256 nm (14682), 282 (11011), 404
(8768). 31P CP/MAS of 7i: d À2.9, À8.4 (4 kHz).
X-ray data for 6: C30H34Cl2O2P2PdSi + C3H6O,
colorless crystal (prism), dimensions 0.24 · 0.12 ·
0.08 mm3, crystal system monoclinic, space group
5. Supporting information
˚
˚
3
P21/n, Z = 4, a = 10.515(1) A, b = 20.817(2) A, c =
˚
Crystallographic data for the structural analyses of 2,
3, and 6 has been deposited with the Cambridge Crystal-
lographic Data Centre, CCDC No. 260233 for 2, No.
260234 for 3, and No. 260235 for 6.
˚
15.597(2) A, b = 96.813(2)ꢁ, V = 3390.0(6) A , q =
1.473 g/cm3, T = 100(2) K, hmax = 28.34ꢁ, radiation Mo
˚
Ka, k = 0.71073 A, 0.3ꢁ x-scans with CCD area detec-
tor, covering a whole sphere in reciprocal space, 34582
reflections measured, 8391 unique (R(int) = 0.036), 7303
observed (I > 2r(I)), intensities were corrected for Lor-
entz and polarization effects, an empirical absorption
correction was applied using SADABS [26] based on the
Copies of this information may be obtained free of
charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ UK, fax: (int code) +44 1223
336 033 or e-mail: deposit@ccdc.cam.ac.uk, or on the
web http://www.ccdc.cam.ac.uk.
Laue symmetry of the reciprocal space l = 0.87 mmÀ1
,
Tmin = 0.82, Tmax = 0.93, structure solved by direct
methods and refined against F2 with a full-matrix
least-squares algorithm using the SHELXTL (6.12) soft-
ware package [27], 539 parameters refined, the carbon
atoms of one ethoxy group are disordered over two posi-
tions (60:40%), hydrogen atoms at disordered groups
were treated using appropriate riding models, all other
were refined isotropically, goodness-of-fit 1.02 for ob-
served reflections, final residual values R1(F) = 0.025,
wR(F2) = 0.059 for observed reflections, residual elec-
Acknowledgments
We thank the Deutsche Forschungsgemeinschaft
(SFB 623) and INSTRACTION AG for financial sup-
port, F. Piestert for the results of one experiment, and
Dr. J. Furrer for valuable advice on suspension NMR
spectroscopy.
3
˚
tron density À0.26 to 0.66 e/A .
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