Supported organometallic complexes XVI1: A T-silyl functionalized dppp palladium complex as a precursor for catalysis in interphases

Article abstract of DOI:10.1016/S0022-328X(98)00374-X

The dppp ligand 4(T⁰) being provided with a T-silylfunctionalized (CH₂)₆ spacer in the symmetric position of the C3 bridge is obtained by a simple three step reaction starting with 2-hydroxymethyl-1-hydroxy-7-octene (1) (). 1 is chlorinated to the dichloride 2 which can be hydrosilylated with HSi(OMe)₃ to give 3(T⁰). Finally both chlorine atoms in 3(T⁰) are exchanged by PPh₂. Treatment of (COD)PdCl₂ with 4(T⁰) results in the formation of the T-silylfunctionalized palladium complex 5(T⁰).

Full text of DOI:10.1016/S0022-328X(98)00374-X

Journal of Organometallic Chemistry 558 (1998) 235–237
Preliminary communication
Supported organometallic complexes XVI1
A T-silyl functionalized dppp palladium complex as a precursor for
catalysis in interphases
Ekkehard Lindner *, Anja Enderle, Andreas Baumann
Institut fu¨r Anorganische Chemie der Uni6ersita¨t Tu¨bingen, Auf der Morgenstelle 18, D-72076, Tu¨bingen, Germany
Received 12 November 1997
Abstract
The dppp ligand 4(T0) being provided with a T-silylfunctionalized (CH2)6 spacer in the symmetric position of the C3 bridge is
obtained by a simple three step reaction starting with 2-hydroxymethyl-1-hydroxy-7-octene (1) (Scheme 1). 1 is chlorinated to the
dichloride 2 which can be hydrosilylated with HSi(OMe)3 to give 3(T0). Finally both chlorine atoms in 3(T0) are exchanged by
PPh2. Treatment of (COD)PdCl2 with 4(T0) results in the formation of the T-silylfunctionalized palladium complex 5(T0). © 1998
Elsevier Science S.A. All rights reserved.
Keywords: Phosphines; Immobilized complex; Palladium
1. Introduction
The functionalized ligand was introduced in a palla-
dium complex.
The application of hybrid organometallic catalysts
has recently attracted much interest, since they combine
both the advantages of homogeneous and heteroge-
neous catalysis [1,2]. In the concept of interphases,
which we have recently introduced [1], the catalytically
active center is incorporated in a stationary phase con-
sisting of a swellable polymer, a spacer unit and the
reactive organometallic complex. To achieve high mo-
bility it is of importance in which way the spacer is
connected to the complex center and the matrix. In this
communication we want to introduce a modified bis
(diphenylphosphino)propane ligand (dppp) carrying a
T-silylfunctionalized spacer fragment in the symmetric
position of the C3 bridge. Diphos ligands play an
important role in several catalytic processes like hydro-
formylation [3] and CO/alkene copolymerization [4].
2. Results and discussion
A suitable starting compound for the generation of
the T-silylfunctionalized ligand 4(T0) is the diol 1 [5],
since it already contains the main building blocks of
4(T0) (T denotes alkoxylsilanes with three Si–O bonds,
the superscript denotes the number of Si–O–Si bonds).
It can easily be chlorinated with SOCl2 to the dichloride
2 with preservation of the terminal double bond. In the
following step the hydrosilylation is successfully carried
out by using hexachloroplatinic(IV) acid as a catalyst.
Although trichlorosilane generally leads to higher yields
[6,7], trimethoxysilane was employed, because the nec-
essary alkoholysis would substitute all chlorine atoms.
The reaction can easily be monitored 1H-NMR spectro-
scopically, in the course of which the signals of the
allylic groups disappear. Due to its T-silylfunction com-
* Corresponding author. Fax: +49 7071 295306.
1 Part XV, see Ref. [1].
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00374-X

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E. Lindner et al. / Journal of Organometallic Chemistry 558 (1998) 235–237
pound 3(T0) is sensitive toward moisture and must be
handled under a dry inert gas atmosphere.
the two phosphorus atoms reduces leaching and cata-
lyst deactivation. In contrast to our previous work [1,2],
the spacer unit was not attached directly to both phos-
phorus atoms. By connecting it with the symmetric
position of the C3 bridge, the highest possible mobility
of the ligand is guaranteed, since flexibility in the
interphase strongly controls the catalytic activity of the
reactive center.
Since cationic palladium dppp complexes play an
important role in the alkene/CO copolymerization [4]
the diphos ligand 4(T0) was reacted with (COD)PdCl2
in THF. After a short time the T-silylfunctionalized
palladium complex 5(T0) was obtained as a yellow
highly viscous oil. The 31P{1H} NMR spectrum of 5(T0)
displays the expected resonance at l 18.7. The chemical
shift corresponds well with that one of (dppp)PdCl2 [8].
Further investigations are devoted to the catalytic
activity of a cationic variant of complex 5(T0) in inter-
phases and will be published elsewhere.
In a final step the colorless diphos ligand 4(T0) is
obtained by treatment of 3(T0) with LiPPh2 in THF.
Because of the high boiling point (\220°C in a vac-
uum of 0.5 mbar) and the presence of a T-silylfunction
it is not possible to purify 4(T0) by distillation or
chromatography. Therefore the crude product was ex-
tracted with n-pentane from the reaction mixture lead-
ing to a wax-like compound, which is sensitive toward
air and moisture.
The substitution of the chlorines for diphenylphos-
phino groups leads to a splitting of the 13C signals in
the 13C{1H} NMR spectrum caused by the interaction
of carbon atoms C1–C3 and those of the aromatic
skeleton with the phosphorus nuclei. The C1 methylene
groups and the ipso carbon atoms of the phenyl rings
are magnetically inequivalent and give rise to AXX%
multiplet patterns.
The presented synthesis of diphos with a T-silylfunc-
tionalized spacer unit is not only limited to obtain the
ligand 4(T0), it also allows several modifications, which
we are currently working on: according to Scheme 1 it
is possible to realize a general route for the access to
diphos ligands with different spacer lengths and
organophosphines. A variation of the substituents at
both phosphorus atoms enables to select an electronic
and stereochemical environment corresponding to the
chosen transition metal complex. The chelating effect of
3. Experimental section
3.1. General remarks
All experiments were carried out under an atmo-
sphere of argon, if not stated otherwise. Tetrahydro-
furan, diethyl ether and n-pentane were distilled from
sodium benzophenone ketyl. PdCl2 was a gift from
Degussa AG. HSi(OCH3)3 was obtained from Fluka.
(COD)PdCl2 [9] and the starting compound 1 [5] were
prepared according to the literature. Elemental analyses
were carried out on a Carlo Erba analyzer, model 1106;
Cl analyses were carried out according to Dirschel and
Erne [10] and Scho¨niger [11]. The high resolution
29Si{1H}, 31P{1H}, and 13C{1H} NMR spectra were
recorded on a Bruker DRX 250 spectrometer at 296 K.
Frequencies and standards are as follows: 29Si{1H}
NMR (DEPT45 pulse sequence): 49.69 MHz, 31P{1H}
NMR: 101.25 MHz, and 13C{1H} NMR 62.90 MHz.
Chemical shifts in the 29Si{1H}, 31P{1H}, and 13C{1H}
NMR spectra were measured relative to partially
deuterated solvent peaks which are reported relative to
DMS. Mass spectra were acquired on a Finnigan MAT
711A modified by AMD ‘Meß- und Datensysteme’ (8
kV, 303 K) and reported as mass/charge (m/z). The IR
spectrum was measured on a Bruker IFS 48 instrument.
3.2. 2-chloromethyl-1-chloro-7-octene (2)
Under ambient atmosphere an excess of SOCl2 (22.2
g, 186.8 mmol) was added dropwise at 0°C to 11.8 g
(74.7 mmol) of 2-hydroxymethyl-1-hydroxy-7-octene
(1). After stirring the solution over night at room
temperature unreacted SOCl2 was removed in vacuo.
Distillation under vacuum gave 9.5 g (65.1%) of 2; b.p.
Scheme 1.

E. Lindner et al. / Journal of Organometallic Chemistry 558 (1998) 235–237
237
3.5. 2-dichloro-(2-diphenylphosphinomethyl-1-diphenyl-
54–60°C (0.5 mbar). Anal. Found: C, 55.37; H, 8.18;
Cl, 36.38. C9H16Cl2 (195.13) Calc.: C, 55.40; H, 8.27;
Cl, 36.34%. MS (EI) m/z 193.4 [M+]. IR (film):
w(CH2ꢀ) 3077 (m), w(–CHꢀ) 2934 (m), w(CH2) 2861
phosphine-8-trimethoxysily loctane) palladium(II)
[5(T0)]
A solution of 1.3 g (2.17 mmol) of 4(T0) in 5 ml of
THF was added dropwise to a suspension of 0.62 g
(2.17 mmol) of (COD)PdCl2 in 10 ml of THF. The
mixture was stirred for 3 h at ambient temperature.
Subsequently THF was removed in vacuo and the
reaction mixture was treated with 10 ml of a n-pen-
tane/diethyl ether mixture (1/3) over night. After dry-
ing the product for 3 h in vacuo a yellow viscous oil
was obtained. Anal. Found: C, 53.38 [12]; H, 5.97; Cl,
9.07. C36H46Cl2O3P2PdSi (794.1) Calc.: C, 54.48; H,
5.84; Cl, 8.93%. MS (FD) m/z 793.7 [M+]. 13C{1H}
NMR (CDCl3): l 135.0–128.9 (m, C-phenyl), 51.0
(OCH3), 34.1 (C1), 31.6 (C2), 9.5 (C8). 31P{1H} NMR
(CDCl3): l 18.7.
(w), w(CꢀC) 1640 (m), l(CH2) 1463 (m) cm−1
.
13C{1H} NMR (CDCl3): l 137.8 (C7), 113.8 (C8), 44.7
(C1), 41.6 (C2), 32.7 (C6), 28.6, 28.0 (C3, C5), 25.3
(C4).
3.3. 2-chloromethyl-1-chloro-8-trimethoxysilyloctane
[3(T0)]
A solution of 6.0 g (30.7 mmol) of 2 in 20 ml of
THF was treated with 4.2
g (34.1 mmol) of
trimethoxysilane. Then a suspension of 20 mg (0.039
mmol) of chloroplatinic acid in 20 ml of THF was
added and the reaction mixture was stirred for 3d.
After evaportion of the solvent and distillation under
vacuo 5.6 g (57.3%) of 3(T0) were obtained as a color-
less liquid; b.p. 111–120°C (0.5 mbar). Anal. Found:
C, 45.42; H, 8.26; Cl, 22.34. C12H26Cl2O3Si (317.33)
Calc.: C, 45.70; H, 8.06; Cl, 22.08%. MS (EI) m/z
317.0 [M+]. 13C{1H} NMR (CDCl3): l 50.94 (C9),
45.91 (C1), 42.84 (C2), 33.29, 29.92, 29.59, 26.95,
22.96 (C2 to C6), 9.55 (C8).
Acknowledgements
The support of this research by the Deutsche
Forschungsgemeinschaft (Forschergruppe, Grant No.
154/41-3) Bonn/Bad Godesberg, and by the Fonds der
Chemischen Industrie, Frankfurt/Main is gratefully ac-
knowledged. We are grateful to Degussa AG, Ger-
many, for a generous gift of PdCl2. The authors wish
to thank Priv.-Doz. Dr H.A. Mayer for the helpful
discussion of the NMR spectra.
3.4. 2-(diphenylphosphinomethyl)-1-diphenylphosphine-
8-trimethoxysilyloctane [4(T0)]
A solution of n-BuLi in n-hexane (18.8 ml of a 1.6
M solution) was added dropwise to a solution of 5.6 g
(30.1 mmol) of HPPh2 in 30 ml of THF at 0°C. After
stirring the reaction mixture for 30 min 4.8 g (15.0
mmol) of 3(T0) was added dropwise. The solution was
stirred over night and became almost colorless. 5 ml
of methanol was added and 4(T0) was extracted three
times with 30 ml of n-pentane. After removal of n-
pentane in vacuo 5.8 g (62.4%) of 4(T0) were obtained.
Anal. Found: C, 70.10; H, 7.52. C36H46O3P2Si (616.80)
Calc.: C, 70.03; H, 7.40%. MS (FD) m/z 616.1 [M+].
29Si{1H} NMR (CDCl3): l −41.00. 13C{1H} NMR
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2
(CDCl3): l 139.5 (m, ipso-C-phenyl), 133.3 (d, J(PC)
3
19.2 Hz, o-C-phenyl), 128.9 (d, J(PC) 1.42 Hz, m-C-
phenyl), 128.8 (d, 4J(PC) 1.42 Hz, p-C-phenyl), 51.0
3
(C9), 36.3 (t, J(PC) 9.3 Hz, C3), 35.6 (A part of an
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1
AXX% pattern, ꢀ J(PC)+3J(PC)ꢀ=22.05 Hz, C1), 33.0
(t, 2J(PC) 12.8 Hz, C2), 33.6, 29.9, 29.6, 26.2, 23.0
(C4–C7), 9.6 (C8). 31P{1H} NMR (CDCl3): l −21.0.
.