Tripodal phosphane ligands with novel linker units and their rhodium complexes as building blocks for dendrimer catalysts

Article abstract of DOI:10.1002/ejic.200390019

An efficient strategy for the backbone functionalization of a tripodal phosphane ligand which allows its attachment to solid supports and polymers has been developed. Using pentaerythrol (1) as the starting material, the functionalized phosphane tripod HO

Full text of DOI:10.1002/ejic.200390019

FULL PAPER
Tripodal Phosphane Ligands with Novel Linker Units and Their Rhodium
Complexes as Building Blocks for Dendrimer Catalysts
Ralf A. Findeis[a] and Lutz H. Gade*[a]
Dedicated to Professor Gottfried Huttner on the occasion of his 65th birthday
Keywords: Phosphane ligands / Hydrogenation / Catalysis / Dendrimers / Rhodium
An efficient strategy for the backbone functionalization of a
tripodal phosphane ligand which allows its attachment to
solid supports and polymers has been developed. Using
pentaerythrol (1) as the starting material, the functionalized
lents of the lithium alkoxy derivative of 9 giving the two
functionalized dendrimers G[0]-[OCH2CH2Otriphos]4 (13)
and G[1]-[OCH2CH2Otriphos]8 (16). These were metallated
with four and eight molar equivalents of [Rh(COD)2][BF4] in
phosphane tripod HOCH2CH2OCH2C(CH2PPh2)3 (9) was ob- CH2Cl2, selectively yielding the metallated dendrimers G[0]-
tained in good yield in a four-step synthesis. Reaction of 9
with [Mo(CO)3(MeCN)3] and [Rh(COD)2][A] gave the com-
plexes [{HOCH2CH2OCH2C(CH2PPh2)3}Mo(CO)3] (10) and
[{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)][A] (A = BF4: 11a,
[OCH2CH2OtriphosRh(COD)BF4]4 (14) and G[1]-[OCH2CH2O-
triphosRh(COD)BF4]8 (17). Comparative catalytic hydrogena-
tion of styrene and 1-hexene using [Rh(triphos)(COD)][BF4]
(11a) and the metallodendrimers 14 and 17 showed that the
PF6: 11b), respectively, two of which were characterised fixation to the low generation dendrimers did not alter the
by X-ray diffraction. The carbosilane dendrimer
Si{(CH2)3SiMe2Cl}4 ‘‘G[0]-[Cl]4’’ (12) and its first generation
analogue Si[(CH2)3SiMe{(CH2)3SiMe2Cl}2]4 ‘‘G[1]-[Cl]8’’ (15)
were reacted with, respectively, four and eight molar equiva-
catalytic hydrogenation properties of the catalysts.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
merization of allylic alcohols.[6] Additionally, backbone-
functionalized triphos complexes have been employed in
two-phase catalysis.[7]
The immobilization of molecular catalysts may lead to
catalytic phases which combine the virtues of homogeneous
catalysis (high activity and selectivity, directed catalyst de-
sign) with those of heterogeneous catalysts (e.g. facile cata-
lyst separation and recycling).[1] However, leaching of the
metal is a major practical problem, regardless of the
method of catalyst fixation and the nature of the support
material.[2] This may be suppressed to various degrees by
using polydentate ligands which form thermally and kin-
etically stable complexes with the catalyst metal. Polydent-
ate phosphanes have been widely employed in this context
and tripodal systems, such as the ‘‘triphos’’ ligand
MeC(CH2PPh2)3, are good examples of this capacity.[3]
Their use as ligands in heterogenized metal catalysts re-
quires the functionalization of their backbone structure,
preferentially in the apical position. Modified triphos li-
gands have been employed for the physisorption of Ru and
Rh complexes on oxidic supports[4] and the covalent fixa-
tion of such catalyst precursors to polystyrene.[5] Immobil-
ized triphos-based catalysts have been studied in catalytic
hydrogenation and hydroformylation as well as the iso-
Since the first reports of the dendrimer fixation of mo-
lecular catalysts,[8] a variety of ligands and catalytically act-
ive complexes has been immobilized on the inside and out-
side of dendritic polymers.[9] Due to the importance of pho-
sphanes in homogeneous catalysis, the immobilization of
both chiral and achiral phosphane ligands has been studied
in a range of such systems.[10] However, there is as yet no
report of the fixation of triphos derivatives to dendrimers.
To this end, efficient preparative methods for the synthesis
of functionalized triphos ligands were required. Important
contributions to this field have been reported by Bianchini
and Huttner and their co-workers in recent years.[3Ϫ7,11Ϫ16]
Previously published syntheses of such derivatives partially
suffer from the nontolerance of certain functional groups
(e.g. C-C multiple bonds)[11] or the fact that the phosphanyl
groups are introduced at a very early stage of the reaction
sequence, making subsequent work up more difficult.[12Ϫ16]
Moreover, if expensive (chiral) phosphanyl functions are to
be introduced in an early reaction step of the synthetic path-
way[17] the loss of phosphane during the overall sequence
may be considerable. A strategy in which the phosphane is
introduced in the final step of the ligand-linker synthesis, was
therefore an important objective of our work. In this paper
[a]
´
Laboratoire de Chimie Organometallique et de Catalyse, CNRS
´
UMR 7513, Institut Le Bel, Universite Louis Pasteur,
4, rue Blaise Pascal, 67070 Strasbourg, France
Eur. J. Inorg. Chem. 2003, 99Ϫ110  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0101Ϫ0099 $ 20.00ϩ.50/0
99

R. A. Findeis, L. H. Gade
FULL PAPER
we report the efficient synthesis of triphos derivatives con-
taining an ether-alcohol function in the apical position of the
ligand backbone, their fixation to zeroth- and first-genera-
tion carbosilane dendrimers and their metallation to give cat-
ionic rhodium complexes. These were then employed in a
comparative study as hydrogenation catalysts.
Synthesis and Structural Characterization of the Tripod-
Metal Complexes [{HOCH2CH2OCH2C(CH2PPh2)3}-
Mo(CO)3] (10) and [{HOCH2CH2OCH2C-(CH2PPh2)3}-
Rh(COD)][A] (A؊ ؍ BF4؊: 11a; A؊ ؍ PF6؊: 11b).
In order to assess the structural details and the ligand
properties
of
the
triphosphane
HOCH2CH2-
OCH2C(CH2PPh2)3 (9), it was reacted with one molar
equivalent of [Mo(CO)3(MeCN)3] to yield the yellow, air
stable triphosphane-molybdenum complex [{HOCH2CH2-
OCH2C(CH2PPh2)3}Mo(CO)3] (10; Scheme 2). The 31P
NMR resonance of the coordinated phosphane ligand is
observed at δ ϭ 15.6 ppm (9: δ ϭ Ϫ25.8 ppm) and the
ν(CO) bands appear in the IR spectrum at 1929 and 1834
cmϪ1. The molecular ion peak at m/z ϭ 866 in the mass
spectrum confirms the formulation of the complex.
Results and Discussion
Synthesis of the Tripodal Phosphane
HOCH2CH2OCH2C(CH2PPh2)3 (9)
We chose pentaerythol (1) as the starting material for the
Single crystals of complex 10, which were suitable for an
synthesis of an apically functionalized triphos ligand. This X-ray diffraction study, were obtained by slow diffusion of
tetraalcohol is a cheap basic chemical which possesses a diethyl ether into a CH2Cl2 solution of the compound. The
functionalized neopentane structure and thus appears to be molecular structure of 10 is displayed in Figure 1a along
well suited for the synthetic objective. There are several re- with its principal bond lengths and angles. The phosphane
ports in the literature, namely from Huttner and co- ligand adopts the expected facial coordination mode in a
workers, of the use of this starting material in triphos chem- molybdenum complex having a slightly distorted octahedral
istry; however, these workers decided to functionalize the coordination geometry. The MoϪP distances of 2.5242(9)
˚
apical position after introduction of the phosphane to 2.5302(8) A and the MϪCO bond lengths of 1.965(3) to
groups.[13Ϫ16] As stated above, this sequence will reduce the 1.968(3) A are within the expected range. Both the
˚
overall yields based upon the phosphane starting material. PϪMoϪP and the CϪMoϪC angles, which lie in the
Since the diphenylphosphanyl groups referred to in this ranges of 81.11(3) to 84.67(3)° and 84.4(1) to 86.8(1)°, re-
work are model systems for more complex tridentate P- spectively, are below 90° defining a slightly elongated tri-
donor ligands, this point was of particular importance to us. gonal antiprismatic first coordination sphere (Figure 1b).
The four hydroxyl functions in 1 are chemically equiva-
lent, and in order to attach a linker group to only one of
these it had to be differentiated with respect to the others.
This is readily achieved by reaction of 1 with triethyl or-
thoacetate in toluene to give the known methyl trioxabicy-
clooctane derivative 2 (Scheme 1).[18] The unchanged ‘‘ap-
ical’’ OH-function was then coupled with benzyl-protected
2-chloroethanol[19] as a linker unit to give BzOCH2CH2-
OCH2C(CH2O)3CCH3 (3), which, in turn, was hydrolysed
yielding the triol BzOCH2CH2OCH2C(CH2OH)3 (4). After
functional group interconversion with SOCl2 in dry pyrid-
ine, giving the trichloride 5, and hydrogenolytic deprotec-
tion, compound 6 was reacted with Ph2PH under strongly
basic reaction conditions to yield the target phosphane
HOCH2CH2OCH2C(CH2PPh2)3 (9) in good yield.
The differentiation of the OH groups by orthoester pro-
tection requires the multistep sequence in the synthesis of 9
as discussed above. This leads to moderate overall yields of
the triphos derivative in spite of the relatively high yields in
each individual reaction step. It was therefore desirable to
devise a shorter route to compound 9. This was possible via
the 3-chloro-2,2-bis(chloromethyl)propan-1-ol (7), which is
directly accessible from pentaerythrol (Scheme 1).[20] Reac-
In view of the principal objective of this work, the syn-
thesis of cationic triphos-rhodium hydrogenation catalysts
attached to dendritic supports, the ligand-linker unit 9 was
reacted with [Rh(COD)2]BF4 to give the RhI complex
[{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)][BF4] (11a;
Scheme 2) which was characterised by elemental analysis
1
and H, 13C and 31P NMR spectroscopy. The most charac-
teristic spectroscopic feature is the doublet at δ ϭ 4.3 ppm
in the 31P NMR spectrum (1JRh,P ϭ 106.8 Hz) indicating
the equivalence of all three phosphorus nuclei on the NMR
time scale at 293 K. The observation of an essentially un-
changed single phosphorus resonance even at Ϫ80 °C is
consistent with a rapid dynamic exchange, probably accord-
ing to a turnstile mechanism, as was previously observed
for [Rh(triphos)(COD)]PF6 and [Ir(triphos)(COD)]PF6.[21]
We were unable to obtain single crystals of compound 11a
which were suitable for X-ray diffraction. This was
achieved, however, after anion exchange with NH4[PF6] giv-
ing the yellow crystalline complex [{HOCH2CH2-
OCH2C(CH2PPh2)3}Rh(COD)][PF6] (11b; Scheme 2). A
single crystal X-ray structure analysis of complex 11b estab-
lished its molecular structure, which is displayed in Fig-
ure 2a, while the inner coordination environment of the
rhodium atom is highlighted in Figure 2b.
tion of
7 with THP-protected 2-bromoethanol gave
THPOCH2CH2OCH2C(CH2Cl)3 (8), which was converted
The coordination geometry of the complex displayed in
into compound 6 by hydrolytic deprotection. This strategy Figure 2b is a distorted trigonal bipyramid, the apical posi-
provided a facile access to large quantities of the key inter- tion being occupied by the phosphorus atom P(1) and the
mediate 6.
centroid of the olefinic double bond C(5)ϪC(6). Whereas
100
Eur. J. Inorg. Chem. 2003, 99Ϫ110

Tripodal Phosphane Ligands with Novel Linker Units
FULL PAPER
Scheme 1. The two synthetic strategies for the preparation of the ligand-linker 9
As observed in the crystal structure of the molybdenum
complex 10, the oxygen atoms in the HOCH2CH2O- spacer
in 11b adopt a gauche conformation.
The packing of the molecules of 11b in the unit cell is
displayed in Figure 2c. For the sake of clarity, the phenyl
groups of the diphenylphosphane units, and the lattice solv-
ent molecules (CH2Cl2), have been omitted. The molecules
are arranged in such a way that the apical alcohol units of
the tripod ligands face each other forming intermolecular
hydrogen bonds while the PF6 anions are arranged along
channels in the crystal near to the positively charged rhod-
ium complex units.
Scheme 2. Synthesis of the tripod-metal complexes 10 and 11a/b
the RhϪP bond length to the apical phosphane unit
Fixation of [{HOCH2CH2OCH2C(CH2PPh2)3}-
Rh(COD)][BF4] (11a) to Zeroth and First Generation
Carbosilane Dendrimers
˚
[RhϪP(1) 2.303(2) A] is significantly shorter than for those
of the two equatorial phosphanes [RhϪP(2) 2.405(2),
In order to asses the suitability of the apically derivatized
˚
RhϪP(3) 2.406(2) A], the RhϪC distances to the apical triphos ligand 9 for the fixation of rhodium hydrogenation
olefin carbon atoms [RhϪC(5) 2.264(6), RhϪC(6) 2.327(6) catalysts to carbosilane dendrimers, the known zeroth gen-
˚
A] are significantly greater than for the equatorial π-olefin eration dendrimer Si{(CH2)3SiMe2Cl}4, ‘‘G[0]-[Cl]4’’ (12)
˚
ligands [RhϪC(1) 2.180(6), RhϪC(2) 2.155(6) A]. The and
its
first
generation
analogue
Si[(CH2)3-
P(1)ϪRhϪcentroid{C(5)/C(6)} angle of 170.13(4) deviates SiMe{(CH2)3SiMe2Cl}2]4, ‘‘G[1]-[Cl]8’’ (15) [22] were reacted
slightly from the ideal of 180°, while the P(1)ϪRhϪP(2/3) with, respectively, four and eight molar equivalents of the
and P(1)ϪRhϪcentroid{C(1)/C(2)} angles are close to 90°. lithium alkoxy derivative of 9. After work up the two func-
Eur. J. Inorg. Chem. 2003, 99Ϫ110
101

R. A. Findeis, L. H. Gade
FULL PAPER
Figure 1. a) Molecular structure of complex 10; principal bond
˚
lengths (A) and angles (°): MoϪP(1) 2.5292(7), MoϪC(3) 1.966(3),
O(4)ϪC(6) 1.427(4), MoϪP(2) 2.5242(9), C(1)ϪO(1) 1.165(3),
C(6)ϪC(7) 1.497(5), MoϪP(3) 2.5302(8), C(2)ϪO(2), 1.164(4),
C(7)ϪO(5) 1.423(4), MoϪC(1) 1.968(3), C(3)ϪO(3) 1.155(3),
O(4)ϪO(5) 2.751(3), MoϪC(2) 1.965(3), C(5)ϪO(4) 1.403(4);
P(1)ϪMoϪP(2) 84.67(3), C(1)ϪMoϪC(2) 84.4(1), C(4)ϪC(8)Ϫ
P(1) 116.4(4), P(1)ϪMoϪP(3) 84.49(2), C(1)ϪMoϪC(3) 84.9(1),
C(4)ϪC(21)ϪP(2)
117.3(2),
P(2)ϪMoϪP(3)
81.11(3),
C(2)ϪMoϪC(3) 86.8(1), C(4)ϪC(34)ϪP(3) 116.7(2); b) view along
the virtual threefold molecular axis of the tripohos-Mo(CO)3 unit
tionalized dendrimers G[0]-[OCH2CH2Otriphos]4 (13) and
G[1]-[OCH2CH2Otriphos]8 (16) were isolated in high yield
(Scheme 3 and 4).
Figure 2. a) Molecular structure of complex 11b; principal bond
˚
lengths (A) and angles (°):RhϪP(1) 2.303(2), RhϪC(5) 2.264(6),
The dendrimer phosphanes 13 and 16 were characterised
O(1)ϪC(49) 1.411(7), RhϪP(2) 2.405(2), RhϪC(6) 2.327(6),
O(1)ϪC(50) 1.412(7), RhϪP(3) 2.406(2), P(1)ϪC(46) 1.851(5),
C(50)ϪC(51) 1.53(1), RhϪC(1) 2.180(6), P(2)ϪC(48) 1.843(6),
O(2)ϪC(51) 1.55(2), RhϪC(2) 2.155(6), P(3)ϪC(47) 1.849(6);
1
by elemental analysis, H, 13C, 29Si and 31P NMR spectro-
scopy as well as FAB (13) and MALDI-TOF (16) mass
spectrometry. Stirring of 13 and 16 with, respectively, four
and eight molar equivalents of [Rh(COD)2][BF4] in CH2Cl2
selectively gave the metallated dendrimers G[0]-[OCH2CH2-
OtriphosRh(COD)BF4]4 (14) (Scheme 3) and G[1]-[OCH2-
CH2OtriphosRh(COD)BF4]8 (17) (Figure 3). These were
characterised by the analytical and NMR spectroscopic
techniques applied to the phosphane precursors as well as
P(1)ϪRhϪP(2)
87.56(6),
112.9(5),
P(1)ϪC(46)ϪC(45)
P(1)ϪRhϪP(3)
O(1)ϪC(50)ϪC(51)
P(3)ϪC(47)ϪC(45)
115.0(4),
87.11(5),
109.5(6),
117.4(4),
C(49)ϪO(1)ϪC(50)
P(2)ϪC(48)ϪC(45) 116.8(4),
P(2)ϪRhϪP(3)
89.52(5),
C(50)ϪC(51)ϪO(2) 100.8(9); b) ligand arrangement in the first co-
ordination sphere of complex 11b; c) the packing of the molecules
of 11b in the unit cell; for the sake of clarity, the phenyl groups
of the diphenylphosphane units, and the lattice solvent molecules
(CH2Cl2) have been omitted
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Tripodal Phosphane Ligands with Novel Linker Units
FULL PAPER
Comparison of the Catalytic Behavior of the Rhodium
Complexes [Rh(triphos)(COD)][BF4], 11a, 14 and 16
(cat1؊4) in the Hydrogenation of Styrene and 1-Hexene
As outlined in the introduction, the hydrogenation of ol-
efins was to be investigated in a comparative study of the
catalytic properties of the mononuclear triphos-rhodium
complexes [Rh(triphos)(COD)][BF4] (cat1) and 11a (cat2)
as well as their dendrimer-linked derivatives 14 (cat3) and
16 (cat4). Mononuclear triphos-rhodium catalysts have
been studied previously and were found to be active hydro-
genation catalysts for simple nonfunctionalized al-
kenes.[17,21a,23,24] All catalytic tests were carried out at 1 bar
of H2 pressure and 20 Ϯ 1 °C with an equivalent amount
of catalyst (1 mol %), i.e. a constant number of catalytic
sites in the system.
As simple substrates for catalytic hydrogenations styrene
and 1-hexene are frequently chosen, the latter in order to
assess the competition between hydrogenation and alkene
isomerization within the coordination sphere of the cata-
lyst.[25] After an initial induction period, during which the
COD ligand is reduced, the hydrogenation of the styrene
occurs at a constant rate until an almost quantitative con-
version of the substrate. The catalytic activities of the cata-
lysts cat1 Ϫ cat4 did not vary significantly and were found
to be at TOF ϭ 10 hϪ1 under the standard conditions
cited above.
As has been shown by van Leeuwen and co-workers, car-
bosilane metallodendrimer catalysts of the first and second
generation may possess the required molecular dimensions
to allow recycling by membrane filtration.[11] If performed
in batch reactors, this requires catalysts which retain their
original activity after separation and reintroduction to a
catalytic conversion. The dendrimer catalysts cat3 and cat4
were found to be isolable (removal of the solvent and reac-
tion product under vacuum) after a complete conversion
and re-usable for a subsequent cycle without significant de-
crease in activity during the first three cycles of catalyst
isolation and reintroduction to a new batch of substrates.
In order to test the activity of the new dendritic catalysts
towards a second standard substrate employed in hydro-
genation tests, the hydrogenation at 1 bar H2 pressure was
carried out using 1-hexene. A competing reaction in this
transformation is the isomerization of the alkene to a mix-
ture of (E)- and (Z)-2-hexene. The typical course of this
reaction, as followed by GC-MS, is again represented for
cat4 in Figure 4.
Scheme 3. Fixation of 9 to the end groups of the zeroth generation
dendrimer G[0]-[SiMe2Cl]4 (12) to give G[0]-[OCH2CH2Otriphos]4
(13) and subsequent metallation yielding G[0]-[OCH2CH2Otri-
phosRh(COD)BF4]4 (14)
After an induction period, during which the catalytically
active species is generated, the conversion of 1-hexene sets
in, giving hexane, (Z)-2-hexene and (E)-2-hexene with a
turnover frequency of 30 hϪ1 based on the 1-hexene con-
sumed. After the complete consumption of 1-hexene, the
by electrospray mass spectrometry, which confirmed the hydrogenation of (Z)-2-hexene leads to the further produc-
uniformity of the products. The molecular ion peaks were tion of hexane, albeit at a lower rate. The curve representing
observed at m/z ϭ 1002.2 for compound 14, corresponding the generation of hexane levels off when the concentration
to the [(M Ϫ 4BF4)/4]ϩ ion, and at m/z ϭ 1041.3 for the of the Z-isomer has dropped to about 30% of its maximum
octametallated dendrimer 17, corresponding to the [(M Ϫ value. As observed for practically all cationic rhodium hy-
8BF4)/8]ϩ ion.
drogenation catalysts, the conversion of the E-isomer is
Eur. J. Inorg. Chem. 2003, 99Ϫ110
103

R. A. Findeis, L. H. Gade
FULL PAPER
Scheme 4. Fixation of 9 to the end groups of the first generation dendrimer G[1]-[SiMe2Cl]8 (15) to give G[1]-[OCH2CH2Otriphos]8 (16)
Conclusions
much slower and essentially insignificant on the chosen
time scale.[25] Comparison of cat1 Ϫ cat4 showed an overall
In this paper we have presented an efficient strategy for
identical catalytic behaviour.
the backbone functionalization of the triphos ligand which
104
Eur. J. Inorg. Chem. 2003, 99Ϫ110

Tripodal Phosphane Ligands with Novel Linker Units
FULL PAPER
Figure 3. First generation rhododendrimer G[1]-[OCH2CH2OtriphosRh(COD)BF4]8 (17)
robust to allow for several recycling steps. Fixation to the
low-generation dendrimers did not alter the catalytic hydro-
genation properties of the triphos-rhodium catalyst. This
constitutes the basis for the extension of this work to higher
dendrimer generations which is currently under way.
Experimental Section
All manipulations were performed under nitrogen (desiccant P4O10,
Granusic, J. T. Baker) on a high vacuum line using standard
Schlenk techniques, or in a glovebox. All reaction flasks were
heated prior to use by means of three evacuation-refill cycles. Sol-
vents and solutions were transferred by needle-septa techniques.
Solvents were dried according to standard methods and saturated
with nitrogen. The deuterated solvents used for the NMR spectro-
scopic measurements were degassed by three successive ‘‘freeze-
Figure 4. A typical conversion diagram for the hydrogenation of 1-
hexene, represented here for the rhododendrimer 16 (cat4)
˚
pump-thaw’’ cycles and stored over 4 A molecular sieves. Solids
were separated from suspensions by filtration through dried Celite
or by centrifugation. The H, 13C, 19F, 29Si and 31P NMR spectra
1
allows its attachment to solid supports and polymers. We
have also been able to completely characterise two carbosil-
were recorded on Bruker AC 200, Bruker Avance 250 and Bruker
1
AMX 400 FT NMR spectrometers. H and 13C data are listed in
ane dendrimer derivatives and found them to be sufficiently parts per million [ppm] relative to tetramethylsilane and were refer-
Eur. J. Inorg. Chem. 2003, 99Ϫ110 105

R. A. Findeis, L. H. Gade
FULL PAPER
enced using the residual protonated solvent peak (1H) or the car-
bon resonance (13C). 29Si, 19F and 31P NMR spectroscopic data
are listed in ppm relative to, respectively, tetramethylsilane, FCCl3
and 85% H3PO4 as external standards. Infrared spectra were re-
corded on a Nicolet Magna IRTM 750 spectrometer. Elemental
analyses were carried out by the microanalytical service at the
chemistry department at Strasbourg. 4-(Hydroxymethyl)-1-methyl-
2,6,7-trioxabicyclo[2.2.2]octane (2),[18] benzyl 2-chloroethyl
(CH, C-9), 128.4 (CH, C-8), 137.6 (C, C-7) ppm. IR (film): ν˜ ϭ
3413 (vs), 2931 (s), 2878 (s), 1448 (s), 1410 (s), 1094 (s), 1040 (s),
837 (m), 746 (m), 699 (s) cmϪ1. C14H22O5 (270.33) calcd. C 62.20,
H 8.20; found C 61.88, H 8.03.
ether,[19]
diphenylphosphane,[26]
(7),[20] 2-(2-Bromoethoxy)tetrahydropyran,[27]
3-chloro-(2,2-chloromethyl)-
propan-1-ol
[(MeCN)3Mo(CO)3],[28] [Rh(COD)2]BF4,[29] G[0]-[Cl]4 (12),[30]
[31]
[21]
G[1]-[Cl]8 (15)
and [CH3C(CH2PPh2)3Rh(COD)]BF4
were
prepared according to published procedures. All other chemicals
used as starting materials were obtained commercially and used
without further purification.
Preparation of BzOCH2CH2OCH2C(CH2Cl)3 (5): SOCl2 (20.5 g,
172 mmol) was added dropwise to a stirred mixture of BzOCH2CH2-
OCH2C(CH2OH)3 (4; 14.1 g, 52.2 mmol) and dry pyridine (13.6 g,
172 mmol) at 0 °C. After complete addition, the reaction mixture
was stirred for 30 min at 0 °C, then for 30 min at room temperature,
and finally at 110Ϫ120 °C for 2.5 h. After cooling to 0 °C 150 mL
of iced water was added and the aqueous phase thus obtained was
twice extracted with 50 mL of CH2Cl2. The combined organic layers
were treated with 100 mL of dilute HCl and with 2 ϫ 100 mL of
water and were then dried over Na2SO4. The solvent was removed
by distillation at normal pressure, and the residue was purified by
column chromatography to give BzOCH2CH2OCH2C(CH2Cl)3 (5)
as a colourless liquid. Yield: 9.52 g (29.2 mmol, 56%). Rf (Kieselgel,
EtOAc/n-hexane ϭ 1:9) ϭ 0.34. 1H NMR (300.17 MHz, CDCl3,
295 K): δ ϭ 3.53 (s, 2 H, H-3), 3.59Ϫ3.67 (m, 4 H, H-4,5), 3.64 (s,
6 H, H-1), 4.54 (s, 2 H, H-6), 7.25Ϫ7.34 (m, 5 H, H-8,9,10) ppm.
13C{1H} NMR (75.48 MHz, CDCl3, 295 K): δ ϭ 44.3 (CH2, C-1),
46.3 (C, C-2), 68.6 (CH2, C-4/5), 69.3 (CH2, C-4/5), 71.0 (CH2, C-
6), 73.2 (CH2, C-3), 127.6 (CH, C-10), 127.7 (CH, C-9), 128.4 (CH,
C-8), 138.2 (C, C-7) ppm. IR (film): ν˜ ϭ 3029 (w), 2920 (m), 1495
(w), 1453 (m), 1434 (m), 1354 (m), 1307 (m), 1267 (m), 1104 (s), 871
(m), 798 (m), 741 (m), 698 (s), 616 (w) cmϪ1. C14H19Cl3O2 (325.66):
calcd. C 51.63, H 5.88; found C 51.89, H 5.74.
Preparation of BzOCH2CH2OCH2C(CH2O)3CCH3 (3): 4-(Hydro-
xymethyl)-1-methyl-2,6,7-trioxabicyclo[2.2.2]octane (2; 14.3 g,
89.0 mmol) was added to a stirred suspension of finely powdered
KOH (11.2 g, 200 mmol) and benzyl 2-chloroethyl ether (30.9 g,
181 mmol) in 150 mL of DMSO. The reaction mixture was stirred
at 60 °C for 2 h and then cooled to room temperature. Water (500
mL) was then added and the solution thus obtained was extracted
with three portions of Et2O (200 mL). The combined organic ex-
tracts were washed with 100 mL of a saturated aqueous solution
of NaCl, then with 100 mL of water and subsequently dried over
Na2SO4. After removal of the solvent by distillation, the yellow oily
residue was purified by column chromatography to yield BzOCH2-
CH2OCH2C(CH2O)3CCH3 (3) as a colourless, viscous liquid.
Yield: 20.5 g (70.2 mmol, 79%). Rf (Al2O3 60 neutral, EtOAc/n-
1
hexane ϭ 2:8): 0.49. H NMR (300.17 MHz, CDCl3, 295 K): δ ϭ
1.42 (s, 3 H, H-1), 3.23 (s, 2 H, H-5), 3.54Ϫ3.60 (m, 4 H, H-6,7),
4.00 (s, 6 H, H-3), 4.54 (s, 2 H, H-8), 7.25Ϫ7.35 (m, 5 H, H-
10,11,12) ppm. 13C{1H} NMR (75.48 MHz, CDCl3, 295 K): δ ϭ
23.2 (CH3, C-1), 34.6 (C, C-4), 69.0 (CH2, C-3), 69.1(CH2, C-6/7),
69.3 (CH2, C-6/7), 70.9 (CH2, C-8), 72.8 (CH2, C-5), 108.1 (C, C-
2), 127.2 (CH, C-12), 127.3 (CH, C-11), 128.1 (CH, C-10), 137.9
(C, C-9) ppm. IR (film): ν˜ ϭ 3007 (w), 2876 (m), 1485 (m), 1453
(m), 1401 (s) 1354 (m), 1296 (m), 1209 (m), 1165 (m), 1127 (s), 1055
(s), 989 (m), 930 (m), 864 (s), 739 (m), 698 (m), 617 (m) cmϪ1
C16H22O5 (294.35) calcd. C 65.29, H 7.53; found C 65.41, H 7.62.
.
Preparation of HOCH2CH2OCH2C(CH2Cl)3 (6) by Deprotection of
BzOCH2CH2OCH2C(CH2Cl)3 (5): A mixture of BzOCH2CH2-
Preparation of BzOCH2CH2OCH2C(CH2OH)3 (4): A solution of OCH2C(CH2Cl)3 (5; (8.32 mg 25.5 mmol) and 310 mg of Pd/C was
(18.2 g, 61.8 mmol) of BzOCH2CH2OCH2C(CH2O)3CCH3 (3) in stirred in THF at room temp under 1 bar of H2 for 12 h. The reac-
40 mL of methanol and 50 mL of 2  HCl was stirred at room tion mixture was then filtered through celite, the solvent removed by
temperature for 6 h. Solid Na2CO3 (7.51 g, 71.3 mmol) was care-
fully added to the reaction mixture in small portions and the solu-
tion was subsequently stirred for another 18 h at ambient temper-
distillation at normal pressure and the oily residue purified by frac-
tional distillation at reduced pressure giving compound HOCH2-
CH2OCH2C(CH2Cl)3 (6) as a colourless liquid. Yield: 4.88 g
ature. The solvents were removed by distillation, the residue was (20.7 mmol, 81%). B.p.: 97Ϫ99 °C/0.64 Torr. 1H NMR (400.1 MHz,
3
extracted with methanol and the solution was evaporated to dry-
CDCl3, 295 K): δ ϭ 3.48 (s, 2 H, H-3), 3.54 (t, JH,H ϭ 4.3 Hz, 2
3
ness to yield pure BzOCH2CH2OCH2C(CH2OH)3 (4) as a soft
H, H-4/5), 3.59 (s, 6 H, H-1), 3.68 (t, JH,H ϭ 4.3 Hz, 2 H, H-4/5)
amorphous solid. Yield: 14.4 g (53.1 mmol, 86%). 1H NMR ppm. 13C{1H} NMR (100.6 MHz, CDCl3, 295 K): δ ϭ 44.5 (CH2,
(300.17 MHz, CDCl3, 295 K): δ ϭ 3.53 (s, 2 H, H-3), 3.60 (br. s, 4
C-1), 46.5 (C, C-2), 62.0 (CH2, C-5), 68.8 (CH2, C-4), 73.0 (CH2, C-
H, H-4,5), 3.65 (s, 6 H, H-1), 4.54 (s, 2 H, H-6), 7.25Ϫ7.35 (m, 5 3) ppm. IR (film): ν˜ ϭ 3373 (br), 2962 (s), 2877 (s), 1476 (m), 1434
H, H-8,9,10) ppm. 13C{1H} NMR (75.48 MHz, CDCl3, 295 K):
δ ϭ 45.0 (C, C-2), 64.5 (CH2, C-4/5), 69.0 (CH2, C-4/5), 70.8 (CH2,
(s), 1360 (m), 1308 (m), 1126 (s), 1062 (s), 871 (s), 806 (m), 759 (m),
742 (m), 701 (m) cmϪ1. C7H13Cl3O2 (235.54): calcd. C 35.69, H 5.56;
C-6), 72.8 (CH2, C-3), 73.2 (CH2, C-1) 127.7 (CH, C-10), 127.8 found C 35.23, H 5.50.
106
Eur. J. Inorg. Chem. 2003, 99Ϫ110

Tripodal Phosphane Ligands with Novel Linker Units
FULL PAPER
solid directly from the extract. Yield: 6.64 g (9.71 mmol, 73%).
M.p.: 138 °C. 1H NMR (400.14 MHz, CDCl3, 295 K): δ ϭ 2.38 (d,
3
1JP,H ϭ 2.9 Hz, 6 H, H-1), 2.81 (t, JH,H ϭ 4.4 Hz, 2 H, H-4/5),
3
3.24 (s, 2 H, H-3), 3.27 (t, JH,H ϭ 4.4 Hz, 2 H, H-4/5), 7.16Ϫ7.25
(m, 30 H, aromat. H) ppm. 13C{1H} NMR (100.63 MHz, CDCl3,
2
295 K): δ ϭ 37.5Ϫ37.9 (m, CH2, C-1), 41.7 (q, C, JPC ϭ 11.4 Hz,
3
C-2), 60.0 (s, CH2, C-5), 70.5 (s, CH2, C-4), 76.5 (q, CH2, JPC
ϭ
7.6 Hz, C-3), 127.2Ϫ127.5 (m, CH, aromat. C), 131.8Ϫ132.1 (m,
CH, aromat. C), 138.3 (m, C, aromat. C) ppm. 31P{1H} NMR
(161.9 MHz, CDCl3, 295 K): δ ϭ Ϫ25.8 (s) ppm. IR (CH2Cl2): ν˜ ϭ
3395 (br), 3072 (m), 2864 (m), 1585 (w), 1481 (m), 1434 (s), 1405
(m), 1307 (w), 1259 (m), 1120 (s), 1061 (s), 1026 (m), 999 (m), 869
(m), 831 (m), 693 (m) cmϪ1. C43H43O2P3 (684.73): calcd. C 75.43,
H 6.33; found C 75.26, H 6.42.
Preparation of THPOCH2CH2OCH2C(CH2Cl)3 (8): Finely pow-
dered KOH (9.45 g, 168 mmol) was added at room temperature to a
vigorously stirred solution of 3-chloro-2,2-bis(chloromethyl)propan-
1-ol (7; 8.02 g, 41.9 mmol) and (2-bromoethoxy)tetrahydropyran
(26.2 g, 125 mmol) in 40 mL of DMSO. There was a strong evolution
of heat during the addition and the temperature was controlled by
occasional cooling with an ice bath. After complete addition of the
solid KOH the reaction mixture was stirred at 60 °C for another 2 h
and then cooled to room temperature. Water (180 mL) was added,
and the aqueous phase was extracted with 3 ϫ 50 mL of CH2Cl2.
The combined organic extracts were washed with 3 ϫ 50 mL H2O
and then dried over Na2SO4. After removal of the solvent by distilla-
tion the residue was subjected to fractional distillation under reduced
pressure to give THPOCH2CH2OCH2C(CH2Cl)3 (10) as a colourless
liquid. Yield: 9.78 g (30.6 mmol, 73%). B.p.: 115 °C/0.19 Torr. 1H
NMR (400.1 MHz, CDCl3, 295 K): δ ϭ 1.43Ϫ1.57 (m, 6 H, H-7,8,9),
3.44 (s, 2 H, H-3), 3.46Ϫ3.62 (m, 4 H, H-4,5), 3.59 (s, 6 H, H-1),
Preparation of [{HOCH2CH2OCH2C(CH2PPh2)3}Mo(CO)3] (10):
A solution of [(MeCN)3Mo(CO)3] (368 mg, 1.21 mmol) in 5 mL of
acetonitrile was slowly added to a stirred suspension of HOCH2-
CH2OCH2C(CH2PPh2)3 (9; 831 mg, 1.21 mmol) in 10 mL of ace-
tonitrile. The reaction mixture was stirred at ambient temperature
for 16 h and the product was then precipitated by addition of Et2O.
The light brown solid was isolated by filtration, washed with Et2O
and dried under vacuum. Complex [{HOCH2CH2OCH2C(CH2-
PPh2)3}Mo(CO)3] (10) was obtained as an ochre microcrystalline
solid after recrystallisation from acetonitrile/Et2O. Yield: 963 mg
(1.11 mmol, 92%). M.p.: 293 °C (dec.). 1H NMR (300.17 MHz,
CD2Cl2, 295 K): δ ϭ 2.36 (m, 6 H, H-1), 3.43 (s, 2 H, H-3), 3.69
3
3.77Ϫ3.85 (m, 2 H, H-10), 4.69 (t, JH,H ϭ 3.3 Hz, 1 H, H-6) ppm.
13C{1H} NMR (100.6 MHz, CDCl3, 295 K): δ ϭ 19.5 (CH2, C-7/8/
9), 25.6 (CH2, C-7/8/9), 30.8 (CH2, C-7/8/9), 44.5 (CH2, C-1), 46.5
(C, C-2), 62.3 (CH2, C-5), 66.7 (CH2, C-10), 68.8 (CH2, C-4), 70.8
(CH2, C-3), 99.1 (CH, C-6) ppm. IR (film): ν˜ ϭ2942 (s), 2871 (m),
1440 (m), 1352 (m), 1260 (m), 1201 (m), 1128 (s), 1076 (s), 1036 (s),
1020 (m), 986 (m), 871 (m), 814 (w), 742 (w), 702 (w) cmϪ1
.
C12H21Cl3O3 (319.66): calcd. C 45.09, H 6.62; found C 45.39, H 6.38.
3
3
(t, JH,H ϭ 5.6 Hz, 2 H, H-4/5), 3.81 (t, JH,H ϭ 5.6 Hz, 2 H, H-4/
5), 7.08Ϫ7.39 (m, 30 H, aromat. H) ppm. 13C{1H} NMR
(75.48 MHz, CD2Cl2, 295 K): δ ϭ 31.2 (m, CH2, C-1), 41.7 (q, C,
2JPC ϭ 7.1 Hz, C-2), 62.4 (s, CH2, C-5), 73.3 (s, CH2, C-4), 84.4
3
(q, CH2, JPC ϭ 9.8 Hz, C-3), 128.4Ϫ129.3 (m, aromat. C),
132.0Ϫ132.2 (m, aromat. C), 138.8Ϫ139.2 (m, aromat. C), 221.3
(m, CO, C-6) ppm. 31P{1H} NMR (161.9 MHz, CD2Cl2, 295 K):
δ ϭ 15.6 (s) ppm. IR (KBr): ν˜ ϭ 3444 (br), 3057 (w), 2901 (w),
1929 (vs), 1834 (vs), 1481 (m), 1433 (s), 1118 (m), 1082 (m), 999
(w), 831 (m), 737 (m), 697 (s), 623 (m) cmϪ1. MS (FAB): m/z ϭ
866.0 [M ϩ H]ϩ. C46H43MoO5P3 (864.71): calcd. C 63.90, H 5.01;
found C 63.72, H 4.88.
Preparation of HOCH2CH2OCH2C(CH2Cl)3 (6) by Deprotection of
THPOCH2CH2OCH2C(CH2Cl)3 (8): Solid p-toluenesulfonic acid
(220 mg) was added to
a
solution of THPOCH2CH2-
OCH2C(CH2Cl)3 (10; 11.2 g, 35.1 mmol) in 50 mL of methanol.
The reaction mixture was stirred at room temperature for 15 h,
neutralised with solid K2CO3 and the solvent removed by distilla-
tion. The remaining residue was subjected to a fractional distilla-
tion as described above to give 6. Yield: 7.78 g (32.9 mmol, 93%).
Preparation of HOCH2CH2OCH2C(CH2PPh2)3 (9): A solution of
HPPh2 (7.80 g, 41.9 mmol) in 10 mL of DMSO was added to a
vigorously stirred suspension of K2CO3 (32.1 g, 233 mmol) in 45
mL of DMSO and this was followed by the addition of KOH
(3.95 g, 70.4 mmol) in 3.0 mL of degassed water. The deep-red sus-
pension thus obtained was stirred for 30 min at room temperature
and then a solution of of HOCH2CH2OCH2C(CH2Cl)3 (6; 3.14 g,
13.3 mmol) in 15 mL of DMSO was added with a syringe. The
reaction mixture was stirred at 90 °C for 2 h and then at 110 °C
Preparation of [{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)]BF4
(11a) and of [{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)]PF6
(11b): A solution of HOCH2CH2OCH2C(CH2PPh2)3 (9; 766.9 mg,
1.12 mmol) in 15 mL of CH2Cl2 was slowly added to a stirred solu-
for another hour. After cooling, 250 mL of water was added, the tion of [Rh(COD)2]BF4 (454.8 mg, 1.12 mmol) in 15 mL of
aqueous phase separated and the volatile organic components re-
moved in vacuo. The residue was extracted with 2 ϫ 20 mL of
toluene, the solution treated with 2 ϫ 10 mL of degassed water
and then dried over Na2SO4. After removal of the solvent the res-
idue was extracted with methanol and the target compound
HOCH2CH2OCH2C(CH2PPh2)3 (9) was obtained as a colourless
CH2Cl2. The reaction mixture was stirred at room temperature for
14 h, accompanied by a change of colour from red-brown to orange
and the product was then precipitated by addition of pentane. The
yellow, microcrystalline solid obtained after washing with n-pent-
ane and drying in vacuo was the pure complex [{HOCH2CH2-
OCH2C(CH2PPh2)3Rh(COD)}]BF4 (11a).
Eur. J. Inorg. Chem. 2003, 99Ϫ110
107

R. A. Findeis, L. H. Gade
CH2, JPC ϭ 12.4 Hz, C-2), 63.2 (s, CH2, C-4/5), 73.5 (s, CH2, C-
FULL PAPER
11a: Yield: 1.03 g (1.05 mmol, 94%). M.p.: 165 °C (dec.). 1H NMR
2
(300.17 MHz, CD2Cl2, 295 K): δ ϭ 2.41Ϫ2.46 (m, 4 H, H-7exo), 4/5), 79.5 (q, CH2, 3JPC ϭ 17.0 Hz, C-3), 129.8Ϫ135.2 (m, aromat.
2.60 (s, 6 H, H-1), 2.76Ϫ2.82 (m, 4 H, H-7endo), 3.65 (s, 2 H, H-3),
C) ppm. 29Si{1H} NMR (79.49 MHz, CD2Cl2, 295 K): δ ϭ 0.4
3.75 (t, JH,H ϭ 5.2 Hz, 2 H, H-4/5), 3.84 (t, JH,H ϭ 5.2 Hz, 2 H, (s, Si), 18.7 (s, SiϪO) ppm. 31P{1H} NMR (121.51 MHz, CD2Cl2,
H-4/5), 4.08 (s, 4 H, H-6), 7.10Ϫ7.39 (m, 30 H, aromat. H) ppm. 295 K): δ ϭ Ϫ26.9 (s) ppm. MS (FAB): m/z ϭ 3164.3 [M ϩ H]ϩ.
13C{1H} NMR (75.48 MHz, CD2Cl2, 295 K): δ ϭ 30.8 (m, CH2, C192H216O8P12Si5 (3163.93): calcd. C 72.89, H 6.88; found C 72.41,
C-1), 33.6 (s, CH2, C-6), 41.0 (m, C, C-2), 62.3 (s, CH2, C-5), 73.6 H 6.76.
3
3
3
(s, CH2, C-4), 83.3 (q, CH2, JPC ϭ 11.0 Hz C-3), 84.8 (m, CH,
C-7), 128Ϫ135 (m, aromat. C) ppm. 31P{1H} NMR (121.5 MHz,
CD2Cl2, 295 K): δ ϭ 4.3 (d, 1JRhP ϭ 106.8 Hz) ppm. IR (film): ν˜ ϭ
3418 (br), 3051 (w), 2933 (w), 2870 (w), 1483 (m), 1433 (s), 1083
(vs), 1054 (s), 830 (m), 744 (m), 696 (s) cmϪ1. C51H55BF4O2P3Rh
(982.63): calcd. C 62.34, H 5.64; found C 62.11, H 5.75.
Preparation of G[0]-[OCH2CH2OtriphosRh(COD)BF4]4 (14): A so-
lution of G[0]-[OCH2CH2Otriphos]4 (13; 305 mg, 96.3 µmol) in 15
mL of CH2Cl2 was slowly added with a cannula to a stirred solu-
tion of [Rh(COD)2]BF4 (385 mg, 949 µmol) in 10 mL of CH2Cl2.
The reaction mixture was stirred at room temperature for 24 h and
the product was then precipitated by addition of n-pentane. The
precipitate was separated by filtration, washed with 3 ϫ 10 mL
of n-pentane and then dried in vacuo. The reaction product G[0]-
Complex 11b was obtained by addition of NH4PF6 (163 mg,
[OCH2CH2OtriphosRh(COD)BF4]4 (14) was obtained as a yellow
3.46 mmol) in
5
mL of methanol to
a
solution of
solid. Yield: 369 mg (84.7 µmol, 88%). M.p.: 161 °C (dec.). 1H
NMR (300.17 MHz, CD2Cl2, 295 K): δ ϭ 0.01 (s, 24 H, H-6),
0.49Ϫ0.55 (m, 8 H, H-9), 0.60Ϫ0.66 (m, 8 H, H-8), 0.86Ϫ0.91 (m,
8 H, H-7), 2.43 (br. s, 16 H, H-11exo), 2.58 (s, 24 H, H-1), 2.77 (br.
[{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)]BF4 (11a; 170 mg,
0.173 mmol) in 5 mL of methanol. The reaction mixture was stirred
at room temperature for 15 h, the precipitate separated by filtra-
tion, washed with 2 ϫ 3 mL of methanol and 2 ϫ 5 mL of
n-pentane and then dried in vacuo. The complex
[{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)]PF6 (11b) was isol-
3
s, 16 H, H-11endo), 3.61 (s, 8 H, H-3), 3.69 (t, JH,H ϭ 4.9 Hz, 8 H,
3
H-4/5), 3.82 (t, JH,H ϭ 4.9 Hz, 8 H, H-4/5), 4.09 (br. s, 16 H, H-
10), 7.09Ϫ7.37 (m, 120 H, aromat. H) ppm. 13C{1H} NMR
(75.48 MHz, CD2Cl2, 295 K): δ ϭ Ϫ2.0 (s, CH3, C-6), 17.3 (s, CH2,
C-7/8/9), 17.9 (s, CH2, C-7/8/9), 21.1 (s, CH2, C-7/8/9), 30.8 (m,
CH2, C-1), 33.2 (s, CH2, C-10), 40.6 (m, C, C-2), 61.9 (s, CH2, C-
ated as
a
yellow microcrystalline solid. Yield: 160.3 mg
(0.153 mmol, 89%). M.p.: 185 °C (dec.). 1H NMR (300.17 MHz,
CD2Cl2, 295 K): δ ϭ 2.43Ϫ2.49 (m, 4 H, H-7exo), 2.63 (s, 6 H, H-
1), 2.78Ϫ2.85 (m, 4 H, H-7endo), 3.67 (s, 2 H, H-3), 3.78 (t, 3JH,H ϭ
3
3
5), 73.1 (s, CH2, C-4), 83.0 (q, JP,C ϭ 10.2 Hz, CH2, C-3), 84.5
5.2 Hz, 2 H, H-4/5), 3.85 (t, JH,H ϭ 5.2 Hz, 2 H, H-4/5), 4.11 (s,
(m, CH, C-10), 128.2Ϫ135.5 (m, aromat. C) ppm. 29Si{1H} NMR
(79.49 MHz, CD2Cl2, 295 K): δ ϭ 0.2 (s, Si), 17.8 (s, SiϪO) ppm.
31P{1H} NMR (121.51 MHz, CD2Cl2, 295 K): δ ϭ 4.5 (d, 1JRh,P ϭ
4 H, H-6), 7.11Ϫ7.42 (m, 30 H, aromat. H) ppm. 13C{1H} NMR
(75.48 MHz, CD2Cl2, 295 K): δ ϭ 31.2 (m, CH2, C-1), 33.2 (CH2,
C-6), 41.1 (m, C, C-2), 62.5 (CH2, C-5), 73.7 (CH2, C-4), 83.5 (q,
3
˜
104.3 Hz) ppm. IR (KBr): ν ϭ 2913 (m), 2870 (m), 1432 (m), 1250
CH2, JPC ϭ 10.9 Hz C-3), 85.0 (m, CH, C-7), 128Ϫ135 (m,
(w), 1084 (s), 1047 (m), 833 (m), 737 (m), 696 (s) cmϪ1. MS (ESI):
aromat. C) ppm. 19F{1H} NMR (376.47 MHz, CD2Cl2, 295 K):
ϭ 1002.2 [(M Ϫ
4BF4)/4]ϩ. C224H264B4F16O8P12Rh4Si5
δ ϭ Ϫ73.8 (d, JP,F ϭ 715 Hz) ppm. 31P{1H} NMR (121.51 MHz,
1
m/z
CD2Cl2, 295 K): δ ϭ Ϫ143.2 (sept), 5.5 (d, 1JRh,P ϭ 104.4 Hz) ppm.
IR (film): ν˜ ϭ 3419 (br), 2929 (w), 2862 (w), 2815 (w), 1482 (m),
(4355.50): calcd. C 61.77, H 6.11; found C 61.32, H 6.02.
1434 (s), 1122 (m), 1085 (m), 844 (s), 745 (m), 697 (m) cmϪ1
.
C51H55F6O2P4Rh (1040.79): calcd. C 58.86, H 5.33; found C 59.10,
H 5.21.
Preparation of G[0]-[OCH2CH2Otriphos]4 (13): A 1.6  solution of
nBuLi in hexanes (1.40 mL, 2.23 mmol) was added to a stirred
solution of HOCH2CH2OCH2C(CH2PPh2)3 (9; 1.53 mg,
2.23 mmol) in 15 mL of DME at Ϫ78 °C. The reaction mixture
was warmed to ambient temperature and then stirred for another
30 min. After re-cooling to Ϫ78 °C a solution of G[0]-[Cl]4 (12;
Preparation of G[1]-[OCH2CH2Otriphos]8 (16): A 1.6  solution of
318.9 mg, 559 µmol) in 10 mL of DME was added dropwise and nBuLi in n-hexane (1.77 mL, 2.83 mmol) was added to a solution
the reaction mixture was then stirred at ambient temperature for
36 h. After removal of the volatiles, the residue was extracted with
toluene and the extract filtered through Celite. Compound G[0]-
of HOCH2CH2OCH2C(CH2PPh2)3 (9; 1.94 g, 2.83 mmol) in 10 mL
of DME at Ϫ78 °C. The reaction mixture was warmed to room
temperature and then subsequently stirred for 30 min. After re-
[OCH2CH2Otriphos]4 (13) was obtained as a soft amorphous solid cooling to Ϫ78 °C, a solution of G[1]-[Cl]8 (15; 514.0 mg, 353
after removal of the solvent and drying under vacuum. Yield: 1.66 g
µmol) in 15 mL of DME was added with the aid of a syringe and
the reaction mixture was then stirred for 36 h at ambient temper-
(525 µmol, 94%). 1H NMR (300.17 MHz, CDCl3, 295 K): δ ϭ 0.04
(s, 24 H, H-6), 0.50Ϫ0.61 (m, 16 H, H-7, 9), 1.22Ϫ1.35 (m, 8 H, ature. After removal of the volatiles, the residue was extracted with
H-8), 2.55 (s, 24 H, H-1), 2.76 (t, 3JH,H ϭ 4.3 Hz, 8 H, H-4/5), 3.15 toluene and the extract filtered through Celite. After removing the
3
(s, 8 H, H-3), 3.21 (t, JH,H ϭ 4.3 Hz, 8 H, H-4/5), 7.21Ϫ7.36 (m, solvent in vacuo, the reaction product G[1]-[OCH2CH2Otriphos]8
120 H, aromat. H) ppm. 13C{1H} NMR (75.48 MHz, CDCl3,
(16) was obtained as an analytically pure soft solid. Yield: 2.13 g
295 K): δ ϭ Ϫ0.1 (s, CH3, C-6), 19.3 (s, CH2, C-7/8/9), 20.0 (s, (321 µmol, 91%). 1H NMR (300.17 MHz, CDCl3, 295 K): δ ϭ 0.16
CH2, C-7/8/9), 27.3 (s, CH2, C-7/8/9), 40.4 (m, CH2, C-1), 44.9 (q,
108
(s, 48 H, H-6), 0.20 (s, 12 H, H-10), 0.67Ϫ0.77 (m, 48 H, H-7, 9,
Eur. J. Inorg. Chem. 2003, 99Ϫ110

Tripodal Phosphane Ligands with Novel Linker Units
FULL PAPER
11, 13), 1.41Ϫ1.51 (m, 24 H, H-8, 12), 2.71 (s, 48 H, H-1), 2.92 (t,
parison of the recorded mass spectra and retention times with those
3JH,H ϭ 5.4 Hz, 16 H, H-4/5), 3.29 (s, 16 H, H-3), 3.37 92 (t, of authentic samples. The measured relative ratio of the products
3JH,H ϭ 5.4 Hz, 16 H, H-4/5), 7.33Ϫ7.51 (m, 240 H, aromat. H) was calibrated by comparative measurements with known sub-
ppm. 13C{1H} NMR (75.48 MHz, CDCl3, 295 K): δ ϭ Ϫ1.9 (s,
CH3, C-10), Ϫ1.5 (s, CH3, C-6), 17.7 (s, CH2, C-7/8/9), 17.8 (s,
CH2, C-11/12/13), 20.8 (s, CH2, C-7/8/9), 21.8 (s, CH2, C-7/8/9),
22.3 (s, CH2, C-11/12/13), 22.9 (s, CH2, C-11/12/13), 38.1 (m, CH2,
stance ratios using pure substances.
X-ray Diffraction Study of Compounds 10 and 11b: Suitable crystals
of the complexes 10 and 11b were obtained by layering concentrated
solutions of the compounds in dichloromethane with hexanes and
allowing slow diffusion at room temperature. The crystal data were
collected on a Nonius Kappa CCD diffractometer at Ϫ100 °C and
transferred to a DEC Alpha workstation; for all subsequent calcula-
tions the Nonius OpenMoleN package was used.[32] The structures
were solved by direct methods with absorption corrections being part
of the scaling procedure of the data reductions. After refinement of
the heavy atoms, difference Fourier maps revealed the maxima of
residual electron density close to the positions expected for the hydro-
gen atoms; they were introduced as fixed contributors in the structure
2
C-1), 42.8 (q, JP,C ϭ 12.5 Hz, C, C-2), 61.3 (s, CH2, C-4/5), 71.5
3
(s, CH2, C-4/5), 77.4 (q, JP,C ϭ 12.5 Hz, CH2, C-2), 128.1Ϫ140.0
(m, aromat. C) ppm. 29Si{1H} NMR (79.49 MHz, CD2Cl2, 295 K):
δ ϭ0.5 (s, Si), 0.9 (s, SiMe), 17.6 (s, SiMe2O) ppm. 31P{1H} NMR
(121.51 MHz, CDCl3, 295 K): δ ϭ Ϫ27.3 (s) ppm. MS (MALDI-
TOF): m/z ϭ 6642.9 [M]ϩ. C400H468O16P24Si13 (6640.59): calcd. C
72.35, H 7.10; found C 71.83, H 6.93.
˚
factor calculations with fixed coordinates (CϪH: 0.95 A) and iso-
2
˚
tropic temperature factors [B(H) ϭ 1.3 Beqv(C) A ] but not refined.
Full least-square refinements on F2. A final difference map revealed
no significant maxima of electron density. The scattering factor coef-
ficients and the anomalous dispersion coefficients were taken from
ref.[33] Crystal data and experimental details for the crystals of 10 and
11b are given in Table 1.
Preparation of G[1]-[OCH2CH2OtriphosRh(COD)BF4]8 (17): A so-
lution of G[1]-[OCH2CH2Otriphos]8 (16; 717.2 mg, 108 µmol) in 15
mL of CH2Cl2 was added to a stirred solution of [Rh(COD)2]BF4
(351 mg, 864 µmol) in 10 mL of CH2Cl2. The reaction mixture was
stirred at ambient temperature for 24 h and the product sub-
sequently precipitated by addition of pentane. After centrifugation,
the precipitate was washed with 3 ϫ 10 mL of n-pentane and then
dried in vacuo. The metallodendrimer G[1]-[OCH2CH2Otri-
phosRh(COD)BF4]8 (17) was obtained as a yellow powder. Yield:
945 mg (97.2 µmol, 90%). M.p.: 156C (dec.). 1H NMR (400.2 MHz,
CD2Cl2, 295 K): δ ϭ 0.09 (s, 12 H, H-10), 0.20 (s, 48 H, H-6),
0.51Ϫ0.67 (m, 48 H, H-7,9,11,13), 1.28Ϫ1.38 (m, 24 H, H-8,12),
2.45 (m, 32 H, H-15), 2.60 (s, 48 H, H-1), 2.78 (m, 32 H, H-15), 3.62
Table 1. X-ray experimental data of compounds 10 and 11b
10
11b
Formula
C46H43MoO5P3
864.7
monoclinic
P21/n
11.1938(2)
21.3216(4)
17.5362(3)
97.901(5)
4145.6(1)
4
C52H57Cl2F6O2P4Rh
11125.73
monoclinic
C2/c
24.0051(5)
23.5811(5)
18.9749(5)
114.302(5)
9789.3(4)
8
Molecular weight
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
3
(s, 16 H, H-3), 3.70 (m, JH,H ϭ 6.1 Hz, 32 H, H-14), 7.08Ϫ7.50
β (deg)
(m, 120 H, aromat. H) ppm. 13C{1H} NMR (75.48 MHz, CD2Cl2,
295 K): δ ϭ δ ϭ Ϫ1.6 (s, CH3, C-6), 17.9 (s, CH2, C-7/8/9), 18.2
(s, CH2, C-11/12/13), 18.6 (s, CH2, C-7/8/9), 18.6 (s, CH2, C-11/12/
13), 20.9 (s, CH2, C-7/8/9), 23.2 (s, CH2, C-11/12/13), 31.2 (m, CH2,
C-1), 33.5 (s, CH2, C-15), 41.1 (m, C, C-2), 62.3 (s, CH2, C-5), 73.7
3
˚
V (A )
Z
Dcalcd. (g·cmϪ3
F000
)
1.39
1784
0.477
1.53
4624
0.653
173
µ (mmϪ1
)
Temperature (K)
Wavelength (A)
Radiation
Theta limits (deg)
173
3
(s, CH2, C-4), 83.4 (q, JP,C ϭ 10.2 Hz, CH2, C-3), 84.9 (m, CH,
˚
0.71073
Mo-Kα
2.5/27.50
17070
0.71073
Mo-Kα
2.5/27.46
18508
C-14), 128.2Ϫ135.3 (m, aromat. C) ppm. 29Si{1H} NMR
(79.49 MHz, CD2Cl2, 295 K): δ ϭ 0.5 (s, SiMe), 17.6 (s, SiMe2O)
ppm. 31P{1H} NMR (121.51 MHz, CD2Cl2, 295 K): δ ϭ 4.4 (d,
1JRh,P ϭ 106.8 Hz) ppm. IR (KBr): ν˜ ϭ 2912 (m), 2870 (m), 1482
(m), 1433 (s), 1250 (m), 1084 (s), 1051 (s), 833 (m), 743 (m), 695
Number of data measd.
Number of data with I Ͼ 3σ(I)
5986
5327
614
0.042
0.067
1.118
0.338
Number of variables
496
(s), cmϪ1
. MS (ESI): m/z ϭ 1041.3 [(M Ϫ 8
BF4)/8]ϩ.
R
0.036
Rw
0.046
C464H564B8F32O16P24Rh8Si13 (9023.73) calcd. C 61.76, H 6.30;
found C 61.21, H 6.09.
GOF
1.058
Largest peak in final
0.743
Ϫ3
˚
difference (e A
)
CCDC-190059 (10) and -190060 (11b) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or
from the Cambridge Crystallographic Data Center, 12, Union
Road, Cambridge CB2 1EZ, UK; Fax: (internat.) ϩ44Ϫ1223/
336Ϫ033; E-mail: deposit@ccdc.cam.ac.uk].
Catalyst Testing: The catalyst tests were carried out in THF at 1
bar H2 pressure using 1 mol % of rhodium. The course of the cata-
lytic hydrogenation was monitored by GC/MS spectrometry per-
formed with a Shimadzu GC-17A/GCMS-QP5050A. Column:
SGE BPX5, 5% phenyl, polysilyphenylene-siloxane, nonpolar, 30
m, 0.22 mm, carrier gas He. The products were analysed by com-
Acknowledgments
We thank the Deutsche Forschungsgemeinschaft, the CNRS, and
the Institut Universitaire de France for funding and Wacker
Eur. J. Inorg. Chem. 2003, 99Ϫ110
109

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