Versatile phosphite ligands based on silsesquioxane backbones

Article abstract of DOI:10.1002/adsc.200303186

Silsesquioxanes are employed as ligand backbones for the synthesis of novel phosphite compounds with 3,3′-5,5′-tetrakis(tert-butyl)-2,2′- dioxa-1,1′-biphenyl substituents. Both mono- and bidentate phosphites are prepared in good yields. Two types of silse

Full text of DOI:10.1002/adsc.200303186

FULL PAPERS
Versatile Phosphite Ligands Based on Silsesquioxane Backbones
a
a
a
b
Jarl Ivar van der Vlugt, Jens Ackerstaff, Tessa W. Dijkstra, Allison M. Mills,
b
b
c
Huub Kooijman, Anthony L. Spek, Auke Meetsma, Hendrikus C. L.
Abbenhuis, Dieter Vogt *
Schuit Institute of Catalysis, Laboratory of Homogeneous Catalysis, Eindhoven University of Technology, P. O. Box 513,
600 MB Eindhoven, The Netherlands
a
a,
a
5
Phone: ( ‡ 31)-40-247-2483. fax: ( ‡ 31)-40-245-5054, e-mail: d.vogt@tue.nl
b
c
Bijvoet Research Institute, Laboratory for Crystal and Structural Chemistry, Department of Chemistry, Utrecht
University, Padualaan 8, 3584 CH Utrecht, The Netherlands
Crystal Structure Center, Chemical Physics, Materials Science Center, University of Groningen, Nijenborgh 4,
9747 AG Groningen, The Netherlands
Received: October 21, 2003; Accepted: February 26, 2004
Abstract: Silsesquioxanes are employed as ligand pletely condensed oxo-functionalized silsesquioxane
backbones for the synthesis of novel phosphite framework. The coordination of the bidentate ligand
compounds with3,3 '-5,5'-tetrakis(tert-butyl)-2,2'-di- 3 towards Pd, Mo and Rhis studied, bothby NMR
oxa-1,1'-biphenyl substituents. Both mono- and bi- spectroscopy as well as by X-ray crystallography.
dentate phosphites are prepared in good yields. Two Various modes of coordination are shown to be
types of silsesquioxanes are employed as starting possible. The molecular structures for the complexes
materials. The monophosphinite 1 and the mono- trans-[PdCl (3)] (5), cis-[Mo(CO) (3)] (6) and the
2
4
2
phosphite 2 are prepared from the thallium silsesqui- dinuclear complex [{Rh(m-Cl)(CO)} (k -3)] (7) have
2
oxide derived from a completely condensed silses- been determined. In the rhodium-catalyzed hydro-
quioxane framework (c-C H ) Si O SiOTl. The di- formylation of 1-octene high activities, with turnover
5
9
7
7
12
À1
phosphite 3 is synthesized starting with the incom- frequencies of up to 6800 h , are obtained witht he se
pletely condensed monosilylated disilanol (c- new nanosized phosphorus ligands.
C H ) Si O (OSiMePh )(OH) . For monophosphite
5
9
7
7
9
2
2
2
, the corresponding trans-[PtCl (2)] complex 4 is
2
characterized by NMR spectroscopy as well as by X- Keywords: coordination chemistry; homogeneous cat-
ray crystallography, as the first example of a com- alysis; ligand design; phosphorus; silsesquioxanes
Introduction
Polyhedral oligomeric silsesquioxanes (or POSS for
short)[ have now been well established as versatile,
nanostructured and oxidatively inert materials that can
1,2]
[
3]
bereadilysynthesizedonalargescale. Thesemolecular
spherosilicates with the general formula [RSiO ] ,
3
/2 n
in which R stands for an (in)organic group and with
typical values for n of 6, 8, 10 or 12, can be obtained with
a closed or completely condensed framework or withan
Figure 1. Representations of a completely condensed silses-
quioxane witha monosilanol functionality (left) and an
incompletely condensed silsesquioxane structure (Fig- incompletely condensed trisilanol silsesquioxane (right).
ure 1). Usually, withR being a (cyclo)alkyl unit, these
compounds are well soluble in a range of organic
solvents (e.g., THF, toluene, CH Cl , hexane, Et O),
They have been extensively studied for several years
2
2
2
[
4]
and they show good stability in acidic and moderate as homogeneous models for silica supports and as
stability in basic reaction media. Together with their building blocks for inorganic or hybrid materials. The
thermal stability up to temperatures above 200 8C, richsilanolate coordination chemistry, involving main
[5]
[
6]
these characteristics provide a good basis for further group but also early and late transition metals, as well as
investigation of the applicability of these well-defined the applications of silsesquioxanes in both homogene-
7]
structures.
ous and heterogeneous catalysis have been reviewed.[
Adv. Synth. Catal. 2004, 346, 399 ± 412
DOI: 10.1002/adsc.200303186
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
399

FULL PAPERS
Jarl Ivar van der Vlugt et al.
Particularly the area of catalytic epoxidation is subject reported by Pruett and Smithat Union Carbide. [17]
[
8]
of ongoing investigation by several groups, with Phosphites are generally better p-acceptors than phos-
silsesquioxane metal complexes reported to be stable phines and therefore have great potential in hydro-
[
8a]
in 1 M hydrochloric acid. However, the synthesis and formylation. The metal-CO bond is weakened, leading
application of phosphorus ligands based on silsesquiox- to accelerated CO dissociation and hence higher
ane frameworks has hardly received any attention to reaction rates compared to phosphines. Other advan-
[9]
date. In addition, most of the systems reported to date tages include the generally straightforward synthesis of
are peripherally functionalized (dendritic) silsesquiox- phosphites and their stability towards oxidation. Re-
[
18]
anes containing phosphine moieties, tethered by various ports based on bulky monophosphites often showed
[
10,11]
(
mainly alkyl) spacers.
high reaction rates, but most systems suffered from a low
Silsesquioxanes are reported to have electron-with- regioselectivity, which is still a common feature of
[
12]
drawing character similar to conventional silica.
Previous studies withsimple electron-wi tdh rawing
monodentate ligands. Bidentate diphosphite ligands
have been developed to circumvent this problem.[
19]
phosphites already showed interesting effects on the Based on catalytic tests the bridge length between the
regioselectivity and reaction rates in hydroformyla- two phosphorus atoms appeared to have a large
tion.[ Our research goal was therefore the develop- influence on the selectivity of linear aldehyde.
ment of new P-containing ligands, based on these stable
13]
silsesquioxane backbones witht he ir unique properties,
by functionalization of silanol groups withsuitable
phosphorus moieties. This would open up a rather
Results and Discussion
unexplored field of ligand design, leading to new
possibilities for coordination chemistry and homoge- Synthesis of Ligands 1 ± 3
neous catalysis. Due to their nanoscopic dimensions,
these molecules might lead to new, stable catalyst The incompletely condensed silsesquioxane trisilanol
supports for continuous homogeneous catalysis with (c-C H ) Si O (OH) can be corner-capped withSiCl ,
5
9 7
7
9
3
4
[
14]
integrated membrane separation. Since these silses- leaving a chloro-functionalized silsesquioxane. By hy-
quioxanes are also good models for silica surfaces, even drolysis the corresponding monosilanol can be ob-
[
20]
a link towards heterogeneous phase catalysis can be tained. To enhance the reactivity of the siloxy group
foreseen. the silanol is best converted into thallium silsesquioxide
[
21]
We have previously reported on the synthesis and A. The reaction of this thallium silsesquioxide with
application of incompletely condensed silsesquioxane- ClPPh led to the sole formation of the corresponding
2
[
15]
based monophosphites as well as on the synthesis, monophosphinite 1. This compound was fully character-
electronic properties and coordination chemistry of a izedusing H, Cand P NMRspectroscopy aswellasby
1
13
31
[
16]
novel silsesquioxane-based diphosphinite ligand. In elemental analysis. Encouraged by this proof of principle
the present work we describe the design of two mono- that a completely condensed silsesquioxane can be
dentate compounds 1 and 2 as well as a bidentate modified with a phosphorus unit, we decided to synthe-
phosphite compound 3 (Figure 2). The synthesis of the size a bulky monophosphite compound by reaction of the
three ligands is presented together with the coordina- thallium silsesquioxide A withdibenzo[ d, f]-3,3',5,5'-
tion behaviour of diphosphite 3 towards palladium, tetra-tert-butyl[1,3,2]dioxaphosphepin chloride, yielding
molybdenum and rhodium. As a first and preliminary the desired compound 2 in high yield (Scheme 1).
1
3
test reaction to show the applicability of both phosphite
The C NMR spectrum of silsesquioxanes is known to
compounds we have chosen the rhodium-catalyzed be very indicative of the obtained purity and geometry
hydroformylation of 1-octene, a well-known and widely of the product, since the ipso-carbons of the silicon
studied model reaction withindustrial relevance.
The first applications of phosphite ligands in the environment. As expected, the C NMR spectrum of
organic side-groups are very sensitive to their respective
1
3
rhodium-catalyzed hydroformylation of 1-alkenes were compound 2 reflected the 1:3:3 ratio between the ipso-
Figure 2.
400
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Phosphite Ligands Based on Silsesquioxane Backbones
FULL PAPERS
Scheme 1. Synthetic route to compounds 1 and 2: i) SiCl , 3 equivs. NEt , THF; ii) H O; iii) TlOEt, toluene; iv) for 1): ClPPh ,
4
3
2
2
NEt , toluene, r.t. (16 h); for 2): phosphorochloridite, NEt , toluene, r.t. (16 h); R ˆ c-C H .
3
3
5
9
carbons of the cyclopentyl groups, indicative of a C3v
symmetry for the obtained product. In the correspond-
ing 31P NMR spectrum a singlet was present at d ˆ
132.6 ppm, which is a normal chemical shift value for
phosphites. Very recently, the group of Edelmann
published the synthesis of a phosphorus diamide based
on the same structural skeleton as present in 1 and 2, by
reaction of the monosilanol shown in Scheme 1 with
[9c]
P(NMe ) .
2
3
For comparison witht he monodentate compound
based on this completely condensed thallium silsesqui-
oxide framework, diphosphite 3 was synthesized
(
Scheme 2) using a similar procedure as for the diphos-
[
16]
phinites reported previously by our group.
Com-
Scheme 2. Synthetic route to compound 3: i) ClSiMePPh2,
pound 3 was prepared in a one-step reaction in 79%
yield from the incompletely condensed silsesquioxane
disilanol (c-C H ) Si O (OH) OSiMePh (B). This com-
NEt , THF, D (5 min), r.t. (16 h), ii) 2 equivs. phosphoro-
3
chloridite, NEt , toluene, r.t. (16 h); R ˆ c-C H .
3
5
9
5
9
7
7
9
2
2
pound is readily available by selective monosilylation of
[
22]
the corresponding trisilanol (c-C H ) Si O (OH) .
5
9
7
7
9
3
The SiMePh protecting group is used instead of the
2
more commonly used SiMe unit because of crystal
3
engineering reasons, as silsesquioxanes containing this
[
23]
former group have a higher tendency to crystallize.
1
13
Also compound 3 was fully characterized by H, C and
P NMR spectroscopy as well as by elemental analysis.
In the C NMR spectrum of compound 3, th e
31
13
expected 2:2:1:1:1 ratio was observed for the signals
of the ipso-carbons of the cyclopentyl groups on the
silicon atoms in the silsesquioxane framework. Single
crystals, suitable for X-ray analysis, were obtained by
recrystallization from a hot dichloromethane/acetoni-
trile mixture. The molecular structure for this com-
pound is depicted in Figure 3 together with selected
bond lengths and angles.
Figure 3. ORTEP representation of compound 3. Displace-
ment ellipsoids are drawn at the 50% probability level. All
hydrogens atoms are omitted for clarity. Selected bond
lengths (ä) and angles (8):P1ÀO2 1.5911(18); P2ÀO1
Due
to
rotational
freedom
around
the
PÀO(silsesquioxane) bonds, the phosphite groups are
1
1
.589(2); Si5ÀO2 1.6404(18); Si6ÀO1 1.636(2); Si4ÀO9
not constrained to any particular mutual orientation.
À
À
À
.6217(18); Si5 O9 1.6149(18); Si7 O3 1.609(3); Si8 O3
The intramolecular PÀP distance of 7.6782(8) ä in the 1.630(2); P1ÀP2 7.6782(8); Si5ÀO2ÀP1 144.11(11);
solid state seems rather large, but coordination to Si6ÀO1ÀP2 143.17(13); Si4ÀO9ÀSi5 152.30(11); Si7ÀO3ÀSi8
transition metals in a chelating manner may still be 150.05(14).
Adv. Synth. Catal. 2004, 346, 399 ± 412
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FULL PAPERS
Jarl Ivar van der Vlugt et al.
possible and cannot be excluded as yet. As is normally
The geometry around the platinum atom in complex 4
observed for silsesquioxane framework structures the is only slightly distorted square planar, as can be
SiÀOÀSi bonds are slightly bent outward, with an concluded from the angles P1ÀPtÀP2 of 178.36(9)8 and
[
4a]
average angle of around 1508. Total sums around the Cl1ÀPtÀCl2 of 178.74(12)8. Bothsilsesquioxane groups
phosphorus atoms are 299.768 for P1 and 298.948 for P2. are located on the same side of the molecule. This rather
The bond lengths for the −termina× Si5À02 and Si6ÀO1 unexpected phenomenon must result from favourable
bond [1.6404(18) ä and 1.636(2) ä, respectively9 are packing interactions that dominate over steric con-
slightly longer than those for the inter-framework bonds straints in the solid state configuration only. The closest
Si4ÀO9 and Si5ÀO9 of 1.6217(18) ä and 1.6149(18) ä. intramolecular SiÀSi distance between the two silses-
This is an indication of the electron-withdrawing quioxane moieties is Si7ÀSi10 of 7.635(5) ä. The slight
character of the silsesquioxane framework.[16]
distortion from ideal square planarity is also apparent
from the angles P1ÀPtÀCl1 [91.00(10)8] and P1ÀPtÀCl2
[
87.82(10)8]. The intramolecular PÀP distance is
Platinum Complex 4
4.529(4) ä. The PtÀP bond lengths [2.267(3) ä for
Edelmann and co-workers have recently claimed the
formation of a cis-PtCl (P) compound, P being their
2
2
silsesquioxane based phosphorodiamide (c-C H )
6
11 7
[
9c]
Si O OP(NMe ) . However, their conclusions were
8
12
2 2
based on an incorrect interpretation of the observed
coupling constant JPt-P of 2730 Hz, since sucha value
typically indicates a complex with both phosphorus
ligands in a mutual trans fashion.[24] Based on these
findings, we decided to investigate the coordination
behaviour of ligand 2 towards platinum (Scheme 3).
After reaction of 2 equivalents of compound 2 with
PtCl (cod) in CH Cl for 2 hours at room temperature
2
2
2
and subsequent removal of the solvent, a white solid was
obtained. The 31P NMR spectrum showed a singlet at
195
d ˆ 80.3 ppm, together with Pt satellites and a cou-
pling constant J of 4680 Hz, which is characteristic for
Pt-P
Figure 4. ORTEP representation of complex 4, trans-
[
24]
two phosphites coordinated in a trans-fashion.
By [PtCl (2) ]. Displacement ellipsoids are drawn at the 50%
2
2
slow diffusion of CH CN into a CH Cl solution of this probability level. All hydrogen atoms and all cyclopentyl
3
2
2
compound, single crystals could be grown that were substituents are omitted for clarity. Selected bond lengths (ä)
and angles (8): PtÀP1 2.267(3); PtÀP2 2.262(3); PtÀCl1
.279(3); PtÀCl2 2.304(3); P1ÀO1 1.567(6); P2ÀO2 1.569(6);
suitable for X-ray analysis. From the crystallographic
study, it is clear that this complex is indeed trans-
2
Si1ÀO1 1.635(6); Si2ÀO2 1.646(6); Si1ÀO3 1.601(7); Si2ÀO15
[
PtCl (2) ], as is evident from the molecular structure,
2 2
1
1
1
.604(7); P1ÀO27 1.583(7); P1ÀO28 1.601(7); P2ÀO29
.581(7); P2ÀO30 1.598(7); P1ÀP2 4.529(4); Cl1ÀPtÀCl2
78.74(12); P1ÀPtÀP2 178.36(9); P1ÀPtÀCl1 91.00(10);
depicted in Figure 4, together with relevant bond
lengths and bond angles. It is only the second crystal
structure of a monofunctionalized, completely con-
densed silsesquioxane framework, the first one bearing
P1ÀPtÀCl2 87.82(10); P2ÀPtÀCl1 90.31(10); P2ÀPtÀCl2
9
0.87(10); Si1 O1 P1 139.6(4); Si2 O2 P2 141.4(4);
PtÀP1ÀO1 118.4(3); PtÀP2ÀO2 117.4(3); Si1ÀO3ÀSi3
45.3(4); Si2ÀO15ÀSi10 150.2(5).
À
À
À
À
[
25]
an alkyl linker instead of the oxo group.
1
Scheme 3. Reaction of compound 2 withPtCl (cod) to form complex 4, trans-[PtCl (2) ].
2
2
2
402
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Phosphite Ligands Based on Silsesquioxane Backbones
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PtÀP1 and 2.262(3) ä for PtÀP2] are slightly but
significantly longer than for other platinum-phosphite
complexes reported in the literature, while the PtÀCl
bond lengths [2.279(3) ä for PtÀCl1 and 2.304(3) ä for
PtÀCl2) on the contrary are somewhat elongated in
[
26]
comparison withthese reference compounds.
This is a
clear indication of the electron-withdrawing character
of the silsesquioxane framework.
To evaluate whether the diphosphite 3, withteh
sterically constrained 1,1'-biphenyldioxaphosphepin
substituents, would show a different coordination be-
haviour in comparison to the previously reported
diphosphinite
compound
(c-C H ) Si O (OPPh)
5 9 7 7 9 2
OSiMePh2,[ complexation reactions were carried out
16]
withpalladium, molybdenum and rhodium precursors.
Figure 5. ORTEP representation of complex 5, trans-
Palladium Complex 5
[
PdCl (3)]. Displacement ellipsoids are drawn at the 50%
2
probability level. All hydrogen atoms, cyclopentyl sidegroups
and solvent molecules are omitted for clarity. Selected bond
lengths (ä) and angles (8): PdÀP1 2.2859(12); PdÀP2
Complexation of 3 withPdCl (cod) at room temper-
2
31
ature resulted in a fine yellow powder and the P NMR
spectrum showed a singlet at d ˆ 88.9 ppm (Scheme 4).
From this finding alone, no conclusion can be drawn as
to which isomer is formed. There is no general relation-
ship for the chemical shifts of either cis or trans
2
1
.2821(10); PdÀCl1 2.2980(13); PdÀCl2 2.2924(13); P1ÀO2
.560(3); P2ÀO1 1.560(3); Si5ÀO2 1.654(3); Si6ÀO1 1.654(3);
Si4ÀO9 1.623(3); Si5ÀO9 1.603(3); Si7ÀO3 1.610(3); Si8ÀO3
1
.633(3); P1 P2 4.5554(15); Cl1 Pd Cl2 171.55(4);
À
À
À
(
palladium) complexes, to validate the mode of coordi- P1ÀPdÀP2 171.45(5); Cl1ÀPdÀP1 90.41(4); Cl2ÀPdÀP2
nation of the bidentate ligand, on the basis of the 85.12(4;) P1
ÀPdÀCl2 90.69(4); P2ÀPdÀCl1 94.82(5);
Si5ÀO2ÀP1 144.9(2); Si6ÀO1ÀP2 151.3(2); PdÀP1ÀO2
15.98(12); PdÀP2ÀO1 112.63(11); Si4ÀO9ÀSi5 154.7(2);
Si7ÀO3ÀSi8 152.0(2).
position of the NMR signal alone. In order to deduce the
exact configuration of complex 5, a crystallographic
study was carried out on single crystals obtained from
slow diffusion of acetonitrile into a dichloromethane
1
solution of PdCl (2). The molecular structure for com- 2.2924(13) ä (PdÀCl2) correspond well withot eh r
2
[
27]
plex 5 is depicted in Figure 5.
complexes with (bulky) diphosphite structures. Deh-
The molecular structure shows that the palladium nicke has reported on the synthesis and X-ray structural
atom of complex 5 is in a square planar coordination. In analysis of PdCl {P(OSiMe ) }. The PdÀP [2.229(1) ä],
2
3 3
contrast to our earlier studies with the diphosphinite PdÀCl [2.342(2) ä] and PÀO [1.543(3) ä] bond lengths
[
16]
[28]
equivalent where we obtained only the cis-isomer, in are all comparable. The various bond lengths and
the present complex the phosphite units are in a mutual bond angles for the silsesquioxane framework are in the
trans relationship, giving rise to a bite angle for the normal ranges withlittle difference to t he case of free
diphosphite ligand P1ÀPdÀP2 of 171.45(5)8 while the ligand 3 (vide supra).
Cl1ÀPdÀCl2 angle is 171.55(4)8. Th e PÀPdÀCl angles
correspond to 85.12(4)8 and 90.41(4)8. To date, charac-
terization of palladium-diphosphite complexes by X-ray Molybdenum Complex 6
analysis has been rare. The PdÀP bond lengths of
2
.2859(12) ä (PdÀP1) and 2.2821(10) ä (PdÀP ) as well To examine if bidentate coordination in a cis-fashion is
2
as the PdÀCl bond lengths of 2.2980(13) ä (PdÀCl1) allowed for with this sterically congested diphosphite
Scheme 4.
Adv. Synth. Catal. 2004, 346, 399 ± 412
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FULL PAPERS
Jarl Ivar van der Vlugt et al.
Scheme 5.
ligand, Mo(CO) (pip) (pip ˆ piperidine) was reacted
4
2
witha small excess of ligand 3 in dichloromethane for 4
hours at room temperature (Scheme 5). From the
concentrated solution a white powder, complex 6, was
obtained after addition of acetonitrile.
The FT-IR spectrum of 6 showed four absorption
Figure 6. ORTEP representation of complex 6, cis-
bands in the carbonyl region, at 2041.3, 1947.9, 1935.2 [Mo(CO) (3)]. Displacement ellipsoids are drawn at the
4
À1
and 1922.3 cm . These values agree reasonably well 50% probability level. All hydrogen atoms, cyclopentyl
[
29,30]
sidegroups and solvent molecules are omitted for clarity.
Selected bond lengths (ä) and angles(8): MoÀP1 2.4771(10);
MoÀP2 2.4509(10); MoÀC105 2.0471(5); MoÀC106 2.050(4);
MoÀC107 2.023(4); MoÀC108 2.009(4); CÀO 1.13À1.15; P1ÀO3
withot he r cis-Mo(CO) (phosphite) complexes.
In
4
2
31
the P NMR spectrum of the crude reaction mixture a
singlet was observed at d ˆ 149.6 ppm together with a
minor peak at d ˆ 131.3 ppm indicating the small excess
of free ligand. To get a confirmation of the actual
coordination of the ligand to the molybdenum atom, a
crystallographic study was undertaken, since single
crystals could be grown by slow diffusion of acetonitrile
1
.574(3); P2ÀO6 1.575(3); Si1ÀO3 1.653(3); Si5ÀO6 1.650(3);
Si5ÀO10 1.614(3); Si4ÀO10 1.627(4); Si3ÀO16 1.615(5);
Si8ÀO16 1.628(5); P1ÀP2 3.7661(14); P1ÀMoÀP2 99.67(3);
C107-Mo-C108 82.00(16); C105-Mo-C106 171.07(16); C108-
Mo-P1 169.69(13); C107 Mo P2 171.76(11); P1 Mo C105
À
À
À
À
into a dichloromethane solution of Mo(CO) (3). The 88.99(11); P2ÀMoÀC106 89.77(12); P1ÀMoÀC106 87.90(11);
4
molecular structure, as determined by X-ray diffraction, P2ÀMoÀC105 83.09(12);
MoÀC107ÀO13
MoÀP1ÀO3
173.62(17);
119.14(11);
MoÀC105ÀO14
176.61(19);
is depicted in Figure 6. To date, the number of X-ray
structures, found in the Cambridge Crystallographic
MoÀP2ÀO6 118.35(11); P1ÀO3ÀSi1 147.62(19); P2ÀO6ÀSi5
1
46.0(2); Si5ÀO10ÀSi4 150.3(2); Si3ÀO16ÀSi8 161.4(3).
Database, for other Mo(CO) -(di)phosphite complexes
4
is limited to thirteen, of which only four contain
P(OR)(OAr) moieties, (Arˆ any aryl group, R ˆ any
2
non-aryl related substituent).
MoÀP bond lengths of 2.4771(10) ä (MoÀP1) and
The geometry around the molybdenum atom of 2.4509(10) ä (MoÀP2) are in good agreement withthe
[
29,32]
complex 6 is distorted octahedral. In agreement with structures reported by Gray et al.
and by Kee and
[
30]
the IR spectrum measured, the ligand coordinates in a co-workers on Mo complexes containing silyldiphos-
bidentate manner to the molybdenum atom, adopting a phites. The phosphorus-oxygen bond lengths of 1.574(3)
cis-conformation. This means however, that there is ä for P1ÀO3 and 1.575(3) ä for P2ÀO6 are slightly
significant crowding around the center of the molecule, shorter than in the silylphosphite systems (generally
with the dioxaphosphepin moieties repositioned at the above 1.60 ä). These latter ligands are structurally
[
33]
far sides of the molecule. The bite angle P1ÀMoÀP2 is identical to a compound used by Pringle. This implies
9
9.67(3)8, which causes the C107ÀMoÀC108 angle to that the PÀOÀSi angles found in complex 6, P1ÀO3ÀSi1
become as small as 82.00(16)8. This bite angle is at 147.62(19)8 and P2ÀO6ÀSi5 at 146.0(2)8, are consid-
significantly larger than the ideal 908 for a true cis- erably larger than found in the literature, where the
coordination, most likely due to steric constraints of the PÀOÀSi angles are in between 129.98 and 138.58.
phosphite moieties. The geometry around the Mo in the Compared to the Mo complex described by Kee et al.,
equatorial plane (MoÀP1ÀP2ÀC107ÀC108) is slightly the difference is even larger, since the PÀOÀSi angles
deviated from-planarity, as evidenced by the angles within the silyltriphosphite SiR(OP) are around 124 ±
3
[
30c]
C108ÀMoÀP1 of 169.69(13)8 and C107ÀMoÀP2 of 1258.
1
71.76(11)8, leading to a dihedral angle between the
MoÀP1ÀP2 plane and the MoÀC107ÀC108 plane of 3.48.
The CO ligands in the axial positions deviate from the Rhodium Complex 7
ideal plane because the C105ÀMoÀC106 angle is only
1
71.76(11)8. This distortion is significantly larger than The completely different coordination behaviour of
those found for cis-[Mo(CO) (P(OPh) ) ] for which an ligand 3 in Pd complex 5 and Mo complex 6 indicates a
4
3 2
[
31]
angle C ÀMoÀC of 175.5(2)8 was reported.
The high level of flexibility in the chelate ring of this
ax
ax
404
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Phosphite Ligands Based on Silsesquioxane Backbones
FULL PAPERS
diphosphite. We were therefore interested to study the
coordination with a third metal species, the rhodium
[
16,34,35]
[36]
dimer [Rh(m-Cl)(CO) ] . As we
and others have
2
2
previously reported, the corresponding RhCl(CO)(P)2-
complexes normally exhibit trans-coordination of two
phosphorus moieties, although some cis complexes have
[
37]
also been described. Upon reaction of 2 equivalents of
with 1 equivalent of this rhodium precursor in
3
refluxing toluene overnight and subsequent removal of
the solvent a yellow-brown solid was obtained. The
31
P NMR spectrum showed the presence of two prod-
ucts, bothdoublets, and no signal of uncoordinated or
decomposed ligand. The major product ( ꢀ 90% by
integration) appeared at d ˆ 111.9 ppm and is assigned Figure 7. ORTEP representation of complex 7, [{Rh(m-Cl)
2
(
CO)} (k -3)]. Displacement ellipsoids are drawn at the 50%
to trans-[RhCl(CO)(3)]. The value of the coupling
2
probability level. All hydrogens atoms and cyclopentyl
sidegroups omitted for clarity. Selected bond lengths (ä)
and angles(8): Rh1ÀP1 2.1820(8); Rh2ÀP2 2.1768(8);
Rh1ÀCl1 2.4135(8); Rh1ÀCl2 2.4213(10); Rh2ÀCl1
constant J
of 278 Hz is typical for Rh-phosphite
Rh-P
38]
complexes.[ Besides, a minor product at d ˆ 120.9 ppm
was present, witha coupling constant J
of 217 Hz.
Rh-P
The IR spectrum of the solid showed two CO stretch
2
1
1
.4179(9); Rh2ÀCl2 2.4154(10); Rh1ÀC1 1.809(3); Rh2ÀC2
.814(3); C1ÀO17 1.155(4); C2ÀO18 1.140(4); P1ÀO2
À1
vibrations at 2019 and 2009 cm . As withot eh r
literature references on this point, this complex was
À
À
À
.563(2); P2 O1 1.564(2); Si5 O2 1.650(2); Si6 O1
measured in dichloromethane and not as a powder. To 1.652(2); Si4ÀO9 1.630(2); Si5ÀO9 1.619(2); Si7ÀO3
interpret the spectroscopic data correctly, a crystallo- 1.612(2); Si8ÀO3 1.643(2); P1ÀP2 6.5417(14); Rh1ÀRh2
graphicstudy was performed on single crystals, grown by 3.5163(5); P1
ÀRh1ÀCl2 177.70(3); P2ÀRh2ÀCl2 176.82(3);
Cl1ÀRh1ÀC1
P1ÀRh1ÀCl1 93.51(3); P2ÀRh2ÀCl1 92.65(3); C1ÀRh1ÀCl2
2.41(10); C2ÀRh2ÀCl2 93.50(10); Cl1ÀRh1ÀCl2 84.18(3);
Cl1ÀRh2ÀCl2 84.22(3); P1ÀRh1ÀC1 89.90(10); P2ÀRh2ÀC2
176.58(10);
Cl1ÀRh2ÀC2
177.58(11);
slow diffusion of acetonitrile into a concentrated CH Cl
2
2
solution of the product. The molecular structure of this
species, complex 7, is depicted in Figure 7, together with
selected bond lengths and angles.
9
8
9.64(10); Rh1ÀCl1ÀRh2 93.40(3); Rh1ÀCl2ÀRh2 93.27(4);
Complex 7 is a rhodium dimer, with the two phosphite
moieties of the ligand spanning the dinuclear metal
center. There is one terminal CO molecule present per
rhodium atom, with two bridging chlorine atoms. The
two phosphorus atoms are mutually cis to one another.
This structure is in agreement with the two observed CO
bands in the IR spectrum. This is due to the distortion of
the Rh1ÀCl1ÀRh2ÀCl2 plane, leading to a so-called
Si5ÀO2ÀP1 156.62(14); Si6ÀO1ÀP2 155.57(15); Rh1ÀP1ÀO2
−
butterfly ± angleh between the Cl1ÀRh1ÀCl2 plane and
the Cl1ÀRh2ÀCl2 plane of 20.58. This existence of two
vibrations was already observed by the group of
Poilblanc.[ Since no uncoordinated ligand was detect-
ed after reaction, complex 7 represents the minor
39]
31
species observed in the P NMR spectrum. The geom-
etry around eachr ho dium atom is square planar, with
the P1ÀRhÀP2 angles at 177.70(3)8 and 176.82(3)8.
These features of the molecular structure of complex 7
are especially visible from a side-view, as presented in
Figure 8.
The skeletal core of the molecule, not regarding any
cyclopentyl groups or the biphenyl derivatives on the
phosphorus atoms, has a high degree of symmetry. The
Cl1ÀRhÀC angles are nearly identical at 176.58(10)8 and
Figure 8. Side view of complex 7, showing the symmetry of
the rhodium atoms in the dimeric species and the butterfly
shape of the Cl1ÀRh1ÀCl2ÀRh2 cycle.
1
77.58(11)8. Th e RhÀP bond lengths are around 2.18 ä,
while the RhÀC and RhÀCl lengths are around 1.80 ±
.81 ä and 2.41 ± 2.42 ä, respectively. All these data complex 7. Th e RÀhCl bond lengths are slightly
compare well with the values found in the mononuclear elongated in comparison to the value [2.370(3) ä] for
1
[
40]
complex [RhCl(CO){P(OPh) } ] witht he exception
the terminal Cl in [RhCl(CO){P(OPh) } ]. The intra-
3
2
3 2
of the Rh-P bonds, which are around ꢀ 0.1 ä shorter in molecular Rh1ÀRh2 distance is 3.5163 ä, which might
Adv. Synth. Catal. 2004, 346, 399 ± 412
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¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
405

FULL PAPERS
Jarl Ivar van der Vlugt et al.
indicate a weak metal-metal interaction. The geometry
around each phosphorus atom is tetrahedral, as indi-
cated by the angles Rh1ÀP1ÀO2 of 115.89(8)8 and
Rh2ÀP2ÀO1 of 114.10(8)8.
Two other dinuclear rhodium-phosphite complexes
with a similar conformation have been characterized by
X-ray crystallography. Cobley et al. have described the
reaction of a calixarene based monophosphite with
Scheme 6.
[
RhCl(CO) ] at different stoichiometries, always end-
2 2
ing up witha mixture of two complexes in the ratio 1 to 4,
31
[41]
based on the P NMR spectrum. The authors pro-
posed an equilibrium between the trans and cis-isomer.
The only product obtained as crystals turned out to be
the cis-isomer. The existence of such an equilibrium in
solution between the two isomers was also proposed by
Poilblanc for other dinuclear rhodium phosphite com-
plexes.[ Furthermore, Gavrilov and co-workers have
published a similar structural motif, employing a
catechol-based monophosphite. The RhÀCl bond
39]
Figure 9.
lengths were around 2.40 ä, the RhÀP bond lengths
With the monophosphite 2, a high activity is achieved
around 2.15 ä.[ Tilley recently reported on a rhodium (entry 1), withan initial turnover frequency of around
42]
À1
dimer withtwo ligand molecules present, together with
5100 h . In addition, an influence of the ligand to metal
two bridging Cl atoms, originating from the rhodium ratio on the catalytic performance was observed. While
[
43]
precursor RhCl (cod) .
Similar bond lengths as in increasing this ratio from 5 to 10, the activity was also
2
2
À1
complex 7 are found for these structures, especially the increased by 33% to a turnover frequency of 6800 h
RhÀP bond lengthand Rh ÀRhdistance.
(entry 2). This activity is an order higher as observed
withcatalysts based on electron-wit hd rawing mono-
[13]
phosphites such as the ligand P(OCH CF ) (I).
2
3 3
Hydroformylation of 1-Octene
However, it does not compete yet witht he sterically
constrained ligand (II) in terms of activity (Figure 9).[
18b]
Since previously reported (di)phosphites have proven to
The regioselectivity remained low, as expected for a
be valuable ligands for the rhodium-catalyzed hydro- monodentate ligand, withan l/b ratio of around 2.2. With
formylation (vide supra), we decided to use this reaction the bidentate ligand 3, a significantly lower activity is
to test the potential application of ligands 1 and 2 in observed (entry 3). This is expected for such a sterically
homogeneous catalysis. The hydroformylation of 1- constrained chelating ligand, yet the regioselectivity
octene was carried out withR (h acac)(CO)
as the remains low, which might be related to too much steric
2
precursor. Because of the often deleterious effect of crowding around the metal centre, leading to an
chlorides on catalytic activity, an RhCl(CO) complex is unselective catalyst and a low activity.
less suitable as catalyst precursor. Standard reaction
conditions of 20 bar of syngas (CO/H ˆ 1/1), a catalyst
2
preformation time of 1 hour and a reaction temperature Conclusions
of 808C were used (Scheme 6). Results of these catalytic
tests withbothligands
Table 1.
2 and 3 are summarized in The synthesis of a monodentate phosphinite 1 and
phosphite 2 as well as the bidentate phosphite com-
Table 1. Rhodium-catalyzed hydroformylation of 1-octene using ligands 2 and 3.[a]
Entry
Ligand
Time [min]
Conversion [%][b]
Selectivity [%][b]
l/b[b]
TOF[c]
1
2
3
2
2
3
20
20
60
41.7
55.2
11.3
68.7
63.7
80.1
2.2
2.2
2.3
5100
6800
500
[
d]
[
a]
Reaction conditions: 1-octene (31.0 mmol), decane (12.5 mmol), toluene (12.7 mL), p ˆ 20 bar, Tˆ 808C,
[
Rh(acac)(CO) ] ˆ 0.39 mM, S:Rh ˆ 4000: 1, ligand:Rh ˆ 5: 1.
2
[
[
[
b]
c]
d]
Determined by GC analysis.
Turnover frequency, defined as (mol substrate converted) ¥ (mol rhodium) h .
À1 À1
Ligand:Rh ˆ 10: 1.
406
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Adv. Synth. Catal. 2004, 346, 399 ± 412

Phosphite Ligands Based on Silsesquioxane Backbones
FULL PAPERS
1
3
pound 3, all based on stable silsesquioxane frameworks, m, c-C
H
), 1.00 (m, c-C
H
9
). C{1H} NMR (CDCl
): d ˆ 132.6
3
5
9
5
(
d, JP-C ˆ 2.4 Hz), 130.7(d, J ˆ 11.4 Hz), 129.5, 129.3, 129.0,
has been described. The coordination chemistry with the
bidentate ligand 3 proved very interesting, as indicated
by the molecular structures obtained for the palladium,
platinum, molybdenum and rhodium complexes. Vari-
ous modes of coordination, including cis, trans and a
bridged dimer, were determined. This can be rational-
ized in terms of steric crowding and an intrinsic large
flexibility range for the silyloxy-functionalized ligands.
In the rhodium-catalyzed hydroformylation of 1-octene,
high activities were obtained for the catalyst containing
P-C
1
3
28.8, 128.1 (d, J ˆ 7.6 Hz), 126.4, 125.3, 124.9, 124.0, 31.6,
P-C
1.5, 31.3, 29.7, 27.3, 27.2, 27.1, 27.0, 26.9, 22.2, 22.1, 22.0 (1:3:3
3
1
ratio for CipsoH). P{1H} NMR (CDCl ): d ˆ 101.6 (s). Anal.
3
calcd. for C H O PSi :C 51.24, H 6.68; found: C 51.35, H 6.78.
4
7
73 13
8
(
c-C H ) Si O O-dibenzo[d, f]-2,2',4,4'-tetra-tert-
5 9 7 8 12
butyl-[1,3,2]dioxaphosphepin (2)
A (0.37 g, 0.39 mmol) was dissolved under moderate heating in
ligand 2. We believe that the structural diversity of 20 mL toluene giving a turbid white suspension. While stirring
silsesquioxanes together with their unique properties at r.t. a solution of dibenzo[d, f]-3,3',5,5'-tetra-tert-butyl-
may offer many new possibilities for the development of [1,3,2]dioxaphosphepin P-chloride (0.16 g, 0.39 mmol) in
4
mL toluene was added dropwise via a syringe and the
new versatile families of phosphorus ligands, with
additional new opportunities for catalyst immobiliza-
tion and recycling.
reaction mixture was stirred for 16 hours. Then salts were
removed by filtration by cannula and the filtrate was concen-
trated by removal of the solvents under vacuum. The product
was extracted by addition of 15 mL hexanes. Solvents were
removed by evaporation, leaving 2 as a brown solid. Yield:
1
0
.42 g (0.31 mmol, 79%). H NMR (CDCl ): d ˆ 7.44 (d, 4H,
Experimental Section
3
1
1
J ˆ 2.4 Hz), 7.18 (d, 4H, J ˆ 2.4 Hz), 1.78 ± 1.33 (br m, c-
1
3
C H ), 1.00 (m, c-C H ). C{1H} NMR (CDCl ): d ˆ 146.0,
5
9
5
9
3
General Remarks
145.3 (d, JP-C ˆ 16.8 Hz), 126.4, 125.3, 124.9, 124.0, 31.6, 31.5,
3
1.3, 29.7, 27.3, 27.2, 27.0, 26.9, 22.2, 22.1, 22.0 (1:3:3 ratio for
Chemicals were purchased from Aldrich, Acros or Merck and
used as received. All preparations were carried out under an
argon atmosphere using standard Schlenk techniques. Solvents
were distilled from sodium/benzophenone (THF, ether, tol-
3
1
CipsoH). P{1H} NMR (CDCl ): d ˆ 132.6 (s).
3
uene and hexanes) or calcium hydride (CH Cl and CDCl ) (c-C H ) Si O (OSiMePh )-bis-dibenzo[d, f]-2,2',4,4'-
2
2
3
5
9
7
7
9
2
prior to use. All glassware was dried by heating under vacuum. tetra-tert-butyl-[1,3,2]dioxaphosphepin (3)
The NMR spectra were recorded on a Varian Mercury 400
1
13
1
B (1.30 g, 1.21 mmol) was dissolved in 20 mL toluene and NEt3
(0.36 g, 3.59 mmol) was added. While stirring at r.t. diben-
spectrometer, referenced to deuterated solvent ( H, C{ H})
31
1
or 85% H PO ( P{ H}) and chemical shifts are given in ppm.
3
4
zo[d, f]-3,3',5,5'-tetra-tert-butyl-[1,3,2]dioxaphosphepin
P-
GC analyses were performed on a Shimadzu 17A chromato-
graphequipped witha 50 m PONA column. Elemental
analysis was performed by Kolbe Mikroanalytisches Labora-
torium, Germany. IR spectra were taken on an AVATAR
E.S.P. 360 FTIR spectrometer. Dibenzo[d, f]-3,3',5,5'-tetra-
chloride (1.15 g, 2.42 mmol) in 5 mL toluene was added
dropwise via a syringe and the reaction continued for 16 hours.
The solution was concentrated to about 5 mL and then
extracted by addition of 10 mL hexanes. After removal of
solvents under vacuum 3 was obtained as a slightly brown solid.
Yield: 2.12 g (90%). Recrystallization from a hot mixture of
CH Cl /CH CN (1:2) afforded colourless rectangular single
[44]
tert-butyl-[1,3,2]dioxaphosphepin P-chloride as well as the
[45]
[46]
metal precursors PdCl (cod), and Mo(CO) (pip)2 were
2
4
2
2
3
prepared according to literature procedures. Also (c-
C H ) Si O Tl (A) and (c-C H ) Si O (OH) (OSiMePh ) (B)
1
crystals, suitable for X-ray analysis. H NMR (CDCl ): d ˆ 7.64
3
5
9
7
8
13
5
9
7
7
9
2
2
1
1
1
[21,22]
(d, 2H, J ˆ 2.4 Hz), 7.62 (d, 2H, J ˆ 2.4 Hz), 7.45 (d, 2H, J ˆ
were prepared according to literature procedures.
1
1
2
2
2
1
.4 Hz), 7.38 (d, 2H, J ˆ 2.4 Hz), 7.32 (dd, 6H, J ˆ 5.6 Hz, J ˆ
CAUTION: Thallium-containing compounds are poison-
ous. Handling of such compounds should be done with utmost
care, also regarding the waste disposal of thallium-containing
compounds.
1
1
.4 Hz), 7.16 (d, 2H, J ˆ 2.4 Hz), 7.14 (d, 2H, J ˆ 2.4 Hz),
.82 ± 1.68 (brs, c-C H ), 1.63 ± 1.40 (br m, c-C H ), 1.56 (s), 1.38
5
9
5
9
(
s), 1.36 (s), 1.28 (s), 0.98 ± 0.89 (br m, c-C H ), 0.15 (s,
5 9
1
3
SiMePh ). C{1H} NMR (CDCl ): d ˆ 152.8, 146.0, 145.6 (d, J
2
3
P-
ˆ
16.8 Hz), 140.5 (d, J ˆ 24.5 Hz), 137.8, 134.1, 133.5, 129.2,
C
P-C
1
(
2
27.7, 126.1 (d, J ˆ 13.7 Hz), 123.8, 35.4, 35.0, 34.6 (d), 31.6
P-C
(
c-C H ) Si O OPPh (1)
5 9 7 8 12 2
d), 31.2 (d), 27.8 (d, JP-C ˆ 3.0 Hz), 27.6 (d, J ˆ 4.5 Hz), 27.3,
P-C
7.0, 26.9, 26.8, 26.7, 24.8, 24.2, 24.1, 23.6, 22.4 (2:1:1:2:1 ratio
(
c-C H ) Si O (OTl) (0.42 g, 0.37 mmol) was dissolved under
5 9 7 8 12
heating in 20 mL toluene giving a colloidal white solution.
3
1
for CipsoH), À 0.4 (SiMePh ). P{1H} NMR (CDCl ): d ˆ 131.3
2
3
(
s). Anal. calcd. for C H O P Si : C 64.09, H 8.07; found: C
104 156 16 2 8
ClPPh (0.08 g, 0.37 mmol) was dissolved in 4 mL hexanes and
2
6
3.85, H 7.95.
this solution was added dropwise to the stirred suspension via a
syringe. The reaction mixture was stirred overnight at r.t. and
the suspension was filtered to remove salts over celite. After
evaporation of the solvents under vacuum 1 was obtained pure
trans-[PtCl (2) ] (complex 4)
1
2
2
as a white powder. Yield: 1.33 g (1.07 mmol, 82%). H NMR
1
2
(
6
CDCl ): ˆ d 7.54 (dt, 4H, J ˆ 7.6 Hz, J ˆ 1.6 Hz), 7.35 (dq,
PtCl (cod) (22.4 mg, 0.06 mmol) and 2 (162.7 mg, 0.12 mmol)
3
2
1
1
H, J ˆ 7.6 Hz, J ˆ 1.6 Hz), 1.77 (br s, c-C H ), 1.61 ± 1.49 (br
were dissolved in 5 mL CH Cl and stirred for 2 hours at r.t.
5
9
2
2
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¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
407

FULL PAPERS
Jarl Ivar van der Vlugt et al.
After removal of the solvent, 4 was obtained as a yellow solid. Rh(Cl)(CO)(3)] (complex 7):
By slow diffusion of CH CN into a CH Cl solution of this
compound, colourless cubic single crystals could be grown,
3
2
2
[
Rh(m-Cl)(CO)2]2 (13.6 mg, 34.9 mmol) and 3 (136.6 mg,
1
70.1 mmol) were stirred in 5 mL of refluxing toluene for 16
suitable for X-ray analysis. H NMR (CDCl ): d ˆ 7.43 (d, 2H,
3
3
1
1
1
1
hours, giving a reddish brown solution. The P{1H} NMR
showed the existence of two species, both doublets. The major
product A ( ꢀ 90% based on NMR intensity) appeared at
111.9 ppm witha coupling constant JRh-P of 278 Hz, while the
minor product B appeared at 120.7 ppm witha coupling
constant JRh-P of 217 Hz. Layering a dichloromethane solution
of the yellow-brown solid with acetonitrile yielded yellow
cubic single crystals. From the X-ray crystallographic analysis
these were shown to be the minor product B (complex 7).
J ˆ 2.4 Hz), 7.41 (d, 2H, J ˆ 2.4 Hz), 7.15 (d, 2H, J ˆ 2.4 Hz),
1
7
.10 (d, 2H, J ˆ 2.4 Hz), 1.83 ± 1.26 (br m, c-C H ), 1.63 (s, t-
5
9
Bu), 1.60 (s, t-Bu), 1.47 (s, t-Bu), 1.36 (s, t-Bu), 1.34 (s, t-Bu),
3
1
1
.06 ± 0.85 (br m, c-C H ). P{1H} NMR (toluene-d ): d ˆ 81.5
5
9
8
(
s, J ˆ 4680 Hz). Anal. calcd for C
H
126 206
Cl O P PtSi : C
Pt-P
2
30
2
16
5
0.81, H 6.97; found: C 50.68, H 7.10.
1
2
1
H NMR (CDCl ): d ˆ 7.78 (br s, 2H), 7.66 (dd, 2H, J ˆ 7.6 Hz,
3
1
J ˆ 2.4 Hz), 7.55 (br d, 2H), 7.49 (br s, 2H), 7.42 (br d, 4H, J ˆ
trans-[PdCl (3)] (complex 5)
7.2 Hz), 7.37 (br d, 2H), 7.15 (br s, 2H), 7.12 (br s, 2H), 1.83 ±
2
1
.18 (br m, c-C H ), 1.61 (s, t-Bu), 1.49 (s, t-Bu), 1.36 (s, t-Bu),
5 9
PdCl (cod) (8.4 mg, 29.4 mmol) and 3 (58.7 mg, 30.1 mmol)
2
1
.34 (s, t-Bu), 1.31 (br s), 0.92 (s, SiMePh ), 0.80 (m, c-C H ).
2
5
9
were stirred in 5 mL CH Cl for 1.5 hto leave 5 as a yellow solid
2
2
31
P{1H} NMR (CDCl ): d ˆ 120.7 (d, J
ˆ 217 Hz), 111.9 (d,
3
Rh-P
after removal of the solvent. Layering with CH Cl /CH CN
2
2
3
À1
J
[
7
ˆ278 Hz). FTIR (ATR mode, solid): n ˆ 2019, 2009 cm
Rh-P
gave yellow rectangular single crystals, suitable for X-ray
st, Rh(CO)]. Anal. calcd. for C H ClO P RhSi : C 59.62, H
1
1
2
105 156 17 2 8
analysis. H NMR (CDCl ): d ˆ 7.66 (dd, 4H, J ˆ 7 6 Hz, J ˆ
3
.43; found: C 58.86, H 7.45.
1
1
1
.2 Hz), 7.43 (d, 2H, J ˆ 2.4 Hz), 7.38 (t, 8H, J ˆ 7.2 Hz), 7.19
1
1
(
d, 2H, J ˆ 2.4 Hz), 7.04 (d, 2H, J ˆ 2.4 Hz), 1.83 ± 1.18 (br m,
c-C H ), 1.61 (s, t-Bu), 1.49 (s, t-Bu), 1.36 (s, t-Bu), 1.34 (s, t-Bu),
5
9
1
3
1
.31 (br s), 0.92 (s, SiMePh ), 0.80 (m, c-C H ). C{1H} NMR
2 5 9
Hydroformylation of 1-Octene
(
CDCl ): d ˆ 146.7, 141.3, 139.7, 137.7, 134.4, 134.1, 132.5,
3
1
3
2
30.9, 129.3, 128.8, 127.5, 126.3, 124.9, 124.1, 36.1, 35.3, 34.6,
2.4, 31.5 (d), 31.2, 30.4, 28.9, 27.9, 27.7, 27.6, 27.5, 27.3, 27.1,
7.0, 26.9, 26.4, 26.3, 24.4, 24.3, 23.8, 23.0, 22.5 (1:2:2:1:1 ratio
The 1-octene was dried by flushing over neutral activated
alumina to remove peroxide impurities. A 75-mL stainless steel
autoclave withinner glass beaker and magnetic stirrer inside
was used. Rh(acac)(CO) (2.00 mg, 7.75 mmol) and the ligand
(
combined and transferred to the autoclave under argon. The
autoclave was purged three times with syngas and then
pressurized to 20 bar. After 1 hof preformation the substrate
solution, containing 1-octene (31.0 mmol), n-decane
3
1
for CipsoH); 1.1 (SiMePh ). P{1H} NMR (CDCl ): d ˆ 88.9 (s).
2
3
2
Anal. calcd for C1
H Cl O P PdSi : C 58.75, H 7.39; found: C
156 2 16 2 8
04
10 equivs.) were dissolved separately in 5 mL toluene, then
58.68, H 7.42.
(
12.5 mmol) and toluene (2.7 mL) was added, 20 bar of syngas
was applied at 808C and the reaction was run for the
appropriate time. The reaction was stopped immediately by
cooling down the autoclave in an ice bath to r.t. and then slowly
depressurizing it. A sample was withdrawn for GC analysis.
cis-[Mo(CO) (3)] (complex 6)
4
Mo(CO) (pip)2 (27.2 mg, 71.9 mmol) and
3
(154.6 mg,
4
79.0 mmol) were dissolved in 10 mL CH Cl and stirred for 2
2
2
hours at r.t. Then the solvent was concentrated to approx. 3 mL
under vacuum, 5 mL of acetonitrile were added to precipitate
the desired product as an off-white powder. After isolation of
the powder, further washing with 4 mL of acetonitrile followed
by drying under vacuum yielded 6 as a light-yellow solid. Upon
slow diffusion of acetonitrile into a dichloromethane solution,
yellow, parallelepiped single crystals were obtained, suitable
Crystal Structure Determination of 4
Intensity data were collected on a Nonius Kappa CCD
diffractometer withrotating anode. T he structure was solved
1
1
by direct methods using SHELXS86,[ and refined on F by
47a]
2
for X-ray analysis. H NMR (CDCl ): d ˆ 7.68 (dd, 4H, J ˆ 7
3
2
1
1
[48]
6
(
2
Hz, J ˆ 1.2 Hz), 7.44 (dd, 6H, J ˆ 7.6 Hz, J ˆ 3.2 Hz), 7.41
least-squares procedures using SHELXL97. All non-hydro-
1
1
1
d, 4H, J ˆ 7.2 Hz), 7.10 (d, 2H, J ˆ 2.4 Hz), 7.01 (d, 2H, J ˆ
gen atoms were refined withanisotropic displacement param-
eters. Hydrogen atoms were constrained to idealized geo-
metries and allowed to ride on their carrier atoms with an
isotropic displacement parameter related to the equivalent
displacement parameter of their carrier atoms. Most cyclo-
pentyl and tert-butyl groups were disordered and restraints
were necessary to obtain reasonable geometries. The unit cells
also contained voids filled withdisordered solvent (CH Cl /
.4 Hz), 1.84 ± 1.68 (br m, c-C H ), 1.62 (s, t-Bu), 1.61 ± 1.07 (br
5
9
m, c-C H ), 1.50 (s, t-Bu), 1.35 (s, t-Bu), 1.32 (s, t-Bu), 1.05 ± 0.83
5
9
(
br m, c-C H ), 0.80 (br m, c-C H ), 0.75 (s, t-Bu), 0.11 (s,
5 9 5 9
13
SiCH Ph ). C{1H} NMR (CDCl ): d ˆ 146.7, 146.3, 140.0,
3
2
3
1
1
2
2
1
39.4, 137.5, 134.3, 134.0, 133.0, 132.1, 129.5, 127.8, 127.6, 126.7,
26.0, 123.8, 36.2, 35.7, 34.5, 34.4, 33.0, 32.3, 31.5 (d), 31.3, 31.2,
8.2, 28.1, 28.0, 27.7, 27.4, 27.2, 27.1, 27.0, 26.9, 26.8, 26.7, 26.6,
6.2 (d), 25.7, 24.9, 24.0, 22.6, 22.1 (1:2:2:1:1 ratio for CipsoH);
2
2
CH CN). The solvent contribution was taken into account
3
31
3
.1 (SiMePh ). P{1H} NMR (CDCl ): d ˆ 149.6 (s). FTIR
using PLATON/SQUEEZE (1920 ä /unit cell and 629 elec-
2
3
(
1
ATR mode, solid): n ˆ 2041.3 (st), 1947.9 (st), 1935.2 (st) and
trons). Structure validation and molecular graphics prepara-
À1
[49]
922.3 cm (st). Anal. calcd. for C
H
MoO P Si : C 60.14,
tion were performed witht he PLATON package.
data are given in Table 2.
Crystal
1
08 156
20
2
8
H 7.29; found: C 60.05, H 7.80.
408
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 399 ± 412

Phosphite Ligands Based on Silsesquioxane Backbones
FULL PAPERS
Table 2. Selected crystallographic data for complex 4.
Crystal Structure Determinations of 3, 5 and 7
4
Diffraction data were collected on a Nonius Kappa CCD
diffractometer withrotating anode at 150 K. PLATON/
DELABS was used to correct the data of complex 3 for
absorption. The structures were solved by direct methods
Formula
C126H206Cl O P PtSi
2 30 2 16
2978.31
Monoclinic
À1
FW (g ¥ mol )
Crystal system
Space group
a (ä)
[47b]
[47c]
(
SHELXS97
methods (DIRDIF99
was done withSHELXL97.
for 3 and SIR97
for 5) and Patterson2
P2 /c (no. 14)
[47d]
1
for 7). Least-squares refinement of F
13.486(2)
27.985(4)
42.300(7)
90.730(10)
15963(4)
4
[48]
Hydrogen atoms were intro-
b (ä)
c (ä)
duced at calculated positions and refined riding on their carrier
atom. Several of the tert-butyl and cyclopentyl moieties were
refined witha disorder model in all three structures. Structures
b (8)
V (ä )
3
3
3
3
and 7 contain voids (393 ä /unit cell for 3 and 2460 ä for 7,
Z
with83 and 418 recovered electrons, respectively) filled with
severely disordered solvents (CH Cl /CH CN). Their contri-
À3
dcalc (g cm )
1.2393(3)
1.115
150
2
2
3
À1
m (Mo-Ka) (mm )
T (K)
bution to the structure factors was taken into account in the
[49]
least-squares refinement using the PLATON/SQUEEZE
Total reflections
164471
25029 (0.143)
0.299
procedure. Structure validation and molecular graphics were
Unique reflections (R )
[49]
int
performed witht he PLATON package.
given in Table 3.
Crystal data are
2
wR (F ) (all data)
2
l (ä)
0.71073
0.098
R (F)
1
F(000)
6272
Crystal Structure Determination of 6
R ˆ S[ j F ± F 2 (mean) j ]S[F ];
2
2
int
o
o
o
The data were collected on a Bruker SMART APEX CCD.
Data integration and global cell refinement was performed
witht he program SAINT. Intensity data were corrected for
Lorentz and polarization effects. The structure was solved by
Patterson methods and extension of the model was accom-
2
2
2
2
2
2
1/2
wR(F ) ˆ [S[w(F ± F ) ]/S[w(F ) ]] ;
o
c
o
R(F) ˆ S( jj F j± j F jj )/S j F j .
o
c
o
Table 3. Selected crystallographic data for ligand 3 and the complexes 5 ±7.
3
5
6
7
Formula
C104H156O P Si
C104H156Cl O P Si Pd
C108H156MoO P Si ¥ 2 C106H156Cl O P Rh Si
20 2 8 2 18 2 2
16
2
8
2
16
2
8
8
‡
solvent
1948.95
¥ 2.52 (CH Cl ) ¥ 1.96 (CH CN) ¥ (CH Cl )
‡ solvent
2
2
3
2
2
À1
a
a
FW (g ¥ mol )
Crystal size (mm)
Crystal system
Space group
a (ä)
b (ä)
c (ä)
a (8)
b (8)
2420.86
2326.86
2281.70
0.24 Â 0.36 Â 0.66 0.09 Â 0.27 Â 0.52
0.52 Â 0.44 Â 0.27
0.05 Â 0.10 Â 0.30
Orthorhombic
P2 2 2 (no. 19)
Triclinic
Monoclinic
Monoclinic
PS (no. 2)
13.5395(1)
14.2578(1)
29.4554(2)
85.7071(3)
88.9721(3)
87.7415(3)
5665.17(7)
2
1.143
0.181
150
93379
P2 /c (no. 14)
P2 /a (no. 14)
1
1
1 1 1
13.7930(1)
32.0407(3)
31.6221(3)
24.605(1)
18.882(1)
25.723(1)
14.2366(10)
27.516(3)
33.591(3)
114.492(10)
90.162(5)
g (8)
V (ä )
3
12717.5(2)
4
11950.6(9)
4
13159(2)
4
Z
À3
a
[a]
dcalc (g cm )
1.265
0.452
150
1.279
0.326
100
1.1517
0.442
À1
a
a
m (Mo-Ka) (mm )
T (K)
Total reflections
150
a
75341
22387 (0.054)
0.1441
0.71073
0.0564
5116
108533
331952
30194 (0.062)
0.110
Unique reflections (R ) 22295 (0.061)
29433 (0.057)
0.2312
0.71073
0.0808
int
2
wR (F ) (all data)
0.1471
0.71073
0.0533
2
l (ä)
0.71073
0.041
R (F)
1
a
a
F(000)
2100
4916
4808
R ˆ S[ j F ± F 2 (mean) j ]/S[F ];
2
2
int
o
o
o
2
2
2
2
2
2
1/2
wR(F ) ˆ [S[w(F ± F ) ]/S[w(F ) ]] ;
o
c
o
R(F) ˆ S( jj F j± j F jj )/S j F j .
o
c
o
[
a]
Without disordered solvent contribution.
Adv. Synth. Catal. 2004, 346, 399 ± 412
asc.wiley-vch.de
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
409

FULL PAPERS
Jarl Ivar van der Vlugt et al.
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dichloromethane solvent molecules was highly disordered and
probably partly occupied. The BYPASS procedure[ was used
to take into account the electron density in the potential
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3
volume of 269 ä in the unit cell. The hydrogen atoms were
included in the final refinement riding on the C-atom as
2
appropriate with U ˆ c  Uequiv. Final refinement on F
iso
carried out by full-matrix least-squares techniques converged
2
at wR(F ) ˆ 0.1057 for 21387 reflections and R(F) ˆ 0.0375 for
1
8554 reflections with F ꢁ in 4.0 s%s(F ) and 975 parameters.
[7] H. C. L. Abbenhuis, Chem. Eur. J. 2000, 6, 25.
o
o
Crystal data are given in Table 3.
[
8] a) H. C. L. Abbenhuis, S. Krijnen, R. A. van Santen,
Chem. Commun. 1997, 331; b) M. Crocker, R. H. Herold,
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Crystallographic data (excluding structure factors) for the
structure(s) reported in this paper have been deposited with
the Cambridge Crystallographic Data Centre as supplemen-
tary publication no. CCDC-220025 (3), 222225 (4), 220026 ±
1
999, 3791; c) S. Krijnen, B. L. Mojet, H. C. L. Abben-
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on application to CCDC, 12 Union Road, Cambridge CB2
1
EZ, UK [fax.: (internat.) ( ‡ 44)-1223/336 ± 033; e-mail:
deposit@ccdc.cam.ac.uk.
6
37; P. P. Pescarmona, T. Maschmeyer, J. C. van der
Acknowledgements
Waal, Chem. Eng. Commun. 2004, 191, 68.
[
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This research was financially supported by the National
Research School Combination for Catalysis (NRSCC) and in
part (A. M. M. and A. L. S.) by the Netherlands Foundation of
Chemical Research (SON) with financial aid from the Nether-
lands Organisation for Scientific Research (CW-NWO). OMG
is acknowledged for a generous gift of various transition metal
precursors. The Erasmus Program of the European Union is
thanked for a travel grant (J. A.). Drs. Michiel Grutters is
thanked for scientific discussions.
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