Heterofunctionalised phosphites built on a calix[4]arene scaffold and their use in 1-octene hydroformylation. Formation of 12-membered P,O-chelate rings

Article abstract of DOI:10.1039/b204604k

The calixarene phosphites L¹-L⁴ were obtained in high yield through reaction of PCl₃/NEt₃ with the mono-functionalised cone-calixarenes p-tert-butylcalix[4]arene(OH)₃OR, in which the R substituents bear an oxygen donor ligand [R = CH₂P(O)Ph₂ (L¹), CH₂CO₂Et (L²), CH₂C(O)NEt₂ (L³), CH₂CH₂OMe (L⁴)]. The calixarene core of the four ligands adopts a cone conformation and, hence, the phosphites become potential P,O-chelating systems. Phosphite L¹ is remarkably stable towards aqueous NaOH, but the presence of slightly acidic water results in phosphonate formation. Slow oxidation of L¹ in air afforded the corresponding mixed phosphine oxide-phosphate. In the complexes [RuCl₂(p-cymene)L¹], [cis-PtCl₂(L¹)₂] (9), trans-[PdCl₂(L¹)₂], [Pd(8-mq)Cl(Lⁿ)] (8-mqH = 8-methyl-quinoline, n = 1-3), [Pd(dmba)Cl(L¹)] (dmbaH = N,N-dimethylbenzylamine), [Pd(η³-C₄H₇)Cl(L²)], [Rh(acac)(CO)Lⁿ] (n = 1-3) and [RhCl(CO)(L¹)₂], the phosphites behave as a monodentate phosphorus donor ligands. Owing to their steric crowding, the two cis-disposed ligands of complex 9 cannot freely rotate about their coordination axis. In the solid state, the calixarene backbones of complex 9 display a so-called 'up-up-out-up' conformation. Chelating phosphite behaviour was found in the cationic complexes [Pd(8-mq)Lⁿ]BF₄ (n = 1-3). In solution, the large, chelating P,O-loop of the latter complexes swings from one side of the metal plane to the other, the dynamics possibly being facilitated by the flexibility of the calixarene backbone. The four oxo-functionalised phosphites were tested as catalysts for 1-octene hydroformylation. The observed reaction rates lie in the range reported for other medium-bulky phosphites. Furthermore, the hydroformylation rate decreases as the donor strength of the side group increases, suggesting binding of the O-donor during catalysis. The L/B ratios lie in the range 1.4-3.6, the highest linear aldehyde selectivity being observed with the phosphite ester L³.

Full text of DOI:10.1039/b204604k

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Heterofunctionalised phosphites built on a calix[4]arene scaffold
and their use in 1-octene hydroformylation. Formation of 12-
membered P,O-chelate rings
Stéphane Steyer,a Catherine Jeunesse,a Dominique Matt,*a Richard Welterb and
Marcel Wesolekc
a Laboratoire de Chimie Inorganique Moléculaire, Université Louis Pasteur, UMR 7513 CNRS,
1 rue Blaise Pascal, F-67008 Strasbourg cedex, France. E-mail: dmatt@chimie.u-strasbg.fr
b Service de Cristallographie, Université Louis Pasteur, Faculté de Chimie, 4 rue Blaise Pascal,
F-67008 Strasbourg cedex, France
c Laboratoire de Chimie des Métaux de Transition et de Catalyse, Université Louis Pasteur,
UMR 7513 CNRS, 4 rue Blaise Pascal, F-67008 Strasbourg cedex, France
Received 13th May 2002, Accepted 11th September 2002
First published as an Advance Article on the web 22nd October 2002
The calixarene phosphites L1–L4 were obtained in high yield through reaction of PCl3/NEt3 with the mono-
functionalised cone-calixarenes p-tert-butylcalix[4]arene(OH)3OR, in which the R substituents bear an oxygen donor
ligand [R = CH2P(O)Ph2 (L1), CH2CO2Et (L2), CH2C(O)NEt2 (L3), CH2CH2OMe (L4)]. The calixarene core of the
four ligands adopts a cone conformation and, hence, the phosphites become potential P,O-chelating systems.
Phosphite L1 is remarkably stable towards aqueous NaOH, but the presence of slightly acidic water results in
phosphonate formation. Slow oxidation of L1 in air afforded the corresponding mixed phosphine oxide–phosphate.
In the complexes [RuCl2(p-cymene)L1], [cis-PtCl2(L1)2] (9), trans-[PdCl2(L1)2], [Pd(8-mq)Cl(Ln)] (8-mqH = 8-methyl-
quinoline, n = 1–3), [Pd(dmba)Cl(L1)] (dmbaH = N,N-dimethylbenzylamine), [Pd(η3-C4H7)Cl(L2)], [Rh(acac)(CO)Ln]
(n = 1–3) and [RhCl(CO)(L1)2], the phosphites behave as a monodentate phosphorus donor ligands. Owing to their
steric crowding, the two cis-disposed ligands of complex 9 cannot freely rotate about their coordination axis. In the
solid state, the calixarene backbones of complex 9 display a so-called ‘up-up-out-up’ conformation. Chelating
phosphite behaviour was found in the cationic complexes [Pd(8-mq)Ln]BF4 (n = 1–3). In solution, the large, chelating
P,O-loop of the latter complexes swings from one side of the metal plane to the other, the dynamics possibly being
facilitated by the flexibility of the calixarene backbone. The four oxo-functionalised phosphites were tested as
catalysts for 1-octene hydroformylation. The observed reaction rates lie in the range reported for other medium-bulky
phosphites. Furthermore, the hydroformylation rate decreases as the donor strength of the side group increases,
suggesting binding of the O-donor during catalysis. The L/B ratios lie in the range 1.4–3.6, the highest linear aldehyde
selectivity being observed with the phosphite ester L3.
Ligands which combine a P() centre with an oxygen-donor
functionality have been intensively investigated over the last
twenty years.1–6 Prominent applications for such ligands are, e.g.
the nickel-catalysed oligomerisation of ethylene with enolato-
phosphine complexes7–9 or the hydroformylation of propene
with rhodium complexes made water-soluble with sulfonato-
phosphines.10 Hybrid P,O-ligands offer distinct advantages over
conventional phosphines or diphosphines. For example, they
may act towards naked d8 metal ions as unsymmetrical chelates
capable of directing an incoming substrate specifically towards
one of the two opposite coordination sites, i.e. trans to P or
trans to O.11 Another important feature of mixed P,O-ligands
concerns their ability to display hemilabile behaviour, a
property which is frequently observed for neutral P,O-chelators
in which the oxygen atom is a weak donor (e.g. an ether
group) and, therefore, may reversibly be substituted.12–16 Such
bidentate ligands have proved useful for increasing the rate of
catalytic reactions by stabilisation of transient key inter-
mediates.17,18 It should also be mentioned that P,O-ligands in
which the oxygen atom is part of a water-solubilising fragment
have attracted much attention in recent years owing to their
potential utility in biphasic catalysis. Interestingly, to date, most
mixed P,O-ligands are based on tertiary phosphines, while
phosphite ligands comprising additional oxygen donors have
scarcely been studied.19–21 This is rather surprising considering
the above-mentioned industrial applications of P,O-phosphine
ligands.
The present work deals with the synthesis, characterisation
and co-ordinative properties of phosphite ligands that contain
a secondary ‘oxygen’ function (amide, ester, phosphine oxide,
ether). The new ligands are based on a calix[4]arene scaffold on
which the auxiliary function has been introduced prior to
P-functionalisation. This work also reports the first example of
a structurally characterised chelate complex derived from
a calixarene-based phosphite. The new P,O-phosphites, which
may form 12-membered chelate complexes, were used in octene
hydroformylation and the influence of the side group was
determined. Phosphites based on a calix[4]arene scaffold
were first reported by Lattman et al.22 Recent publications by
the groups of Pringle,23,24 van Leeuwen25,26 and Röper27 report
the coordination and catalytic chemistry of other calix[n]arene
phosphites (n = 4, 6), but none of these ligands is suitable for the
formation of an unsymmetrical chelate.
Results and discussion
Synthesis and stability of the ligands
In this work, the nomenclature ‘m-H’ specifically refers to
aromatic protons in meta positions on phenolic rings of the
4264
J. Chem. Soc., Dalton Trans., 2002, 4264–4274
This journal is © The Royal Society of Chemistry 2002
DOI: 10.1039/b204604k

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calixarene backbone. The following results illustrate how a
calix[4]arene bearing a single substituent tethered at the lower
rim can be used for the preparation of functional phosphites.
All calixarene phosphites presented herein adopt a cone
conformation.
Reaction of the mono-functionalised calixarene 128 with
PCl3/NEt3 in toluene afforded phosphite L1 in quantitative yield
(eqn. 1). Compound L1 is highly soluble in all common organic
solvents, a property that makes recrystallisation difficult. It
turned out that after careful elimination of NEt3HCl and NEt3
from the reaction mixture (see Experimental section), the
product did not require further purification. The 31P NMR
spectrum of L1 shows two signals, at 107 and 26.1 ppm, corre-
sponding to the phosphite and phosphine oxide fragments,
respectively (cf. 128 ppm for P(OPh)3 and 23 ppm for O=PPh3).
PH proton gives a characteristic doublet at 6.01 ppm [J(PH) =
792 Hz]. The 1H NMR spectrum shows four distinct AB
patterns for the ArCH2 bridging units. All AB separations
were found to be ≥ 0.7 ppm, suggesting a cone conformation.
However, 2D NOESY experiments clearly indicate that a cone
⇔ partial cone exchange, as shown in Scheme 1, takes place.
1
The H NMR spectrum, which displays three But signals of
relative intensity 1:1:2 and two AB patterns for the ArCH2
groups, is consistent with the existence of a symmetry plane. As
revealed by 2D ROESY experiments, the ‘m-H’ protons of the
calixarene unit correlate exclusively with equatorial ArCH2Ar
atoms. This observation unambiguously establishes the cone
structure of L1. Note that this conformation contrasts with that
of Lattman’s calixarene 2, obtained by reacting p-tert-butyl-
calix[4]arene with hexamethylphosphorus triamide/CF3CO2-
H.22 Clearly, the steric crowding of the phosphine oxide group
in precursor 1 prevents trans annulus inversion and, hence,
leads to the selective formation of a cone conformer. It should
be stressed that the use of PCl3/NEt3 for the preparation of
cone-L1 does not result in the formation of a second (isomeric)
product, in contrast to the observations made by Parlevliet
et al., who applied the same methodology to the synthesis of
other calix-phosphites.26 Thus, starting from a monoprotected
calixarene appears to be advantageous for synthesising calix-
[4]arene-based phosphites. Molecular mechanics calculations
have shown that the calixarene core of cone-L1 is significantly
more strained than the hypothetical partial-cone analogue,
paco-L1.29 Corroborating the observations made by Pringle
et al. for another calixarene phosphite,23 we found that dichloro-
methane solutions of L1 were quite stable towards aqueous
NaOH. However, L1 decomposes instantly on treatment with
slightly acidic water (vide infra).
Scheme 1 Proposed dynamics for compound 3.
This was easily deduced from the number of correlations
involving the two methylene groups bordering the phenol ring;
indeed, both possess a CH atom correlating with two aromatic
‘m-H’ protons of the calixarene core, while the other CH
correlates with a single ‘m-H’ (Fig. 1). The other two methylene
Fig. 1 ROESY spectrum of phosphonate 3 (CDCl3).
groups show NOEs, exactly as expected for CH2 groups linking
syn-oriented aryl rings (i.e. the equatorial CHe atoms correlate
with two ‘m-H’ protons, while no cross-peaks involving
axial CHa atoms are observed). The same 2D experiment
also revealed a spatial proximity between the PH group
and the hydroxy group, indicating that the phosphorus atom
Treatment of a dichloromethane solution of L1 with aqueous
NH4Cl results in cleavage of a P–O bond and selective forma-
tion of phosphonate 3 (eqn. 2). This compound was charac-
1
terised by H, 13C, 31P and IR spectroscopy. The phosphonate
signal appears at 1.4 ppm in the 31P NMR spectrum, while the
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is positioned below the cavity. Finally, the 2D spectrum
established a proximity between the PH group and the PPh2
protons. These data allow assignment of structure b (Scheme
2). Note, 3 is a chiral molecule and therefore exists as a mixture
of two enantiomers (not drawn).
Scheme 2 The four possible orientations of the phosphonate group in
paco-3.
Slow oxidation occurred when a solution of L1 was allowed
to stand in air for several days, affording the mixed phosphine
oxide–phosphate 4 (eqn. 3). The phosphate unit is characterised
by a peak at Ϫ23.3 ppm in the 31P NMR spectrum. As expected,
the IR spectrum of 4 shows a strong phosphate band near
1300 cmϪ1 [ν(P᎐O)].
᎐
Scheme 3 The two known cone conformations of calix[4]arene
phosphites.
than an up-out-up-up conformation (Scheme 3). As shown by
van Leeuwen et al., higher δ values are expected (ca. 116 ppm)
for the latter conformation.26
Complexes obtained from phosphites L1–L3
L1 reacts with [RuCl2(p-cymene)]2 to quantitatively afford the
red phosphite complex 8 characterised by a singlet at 92.6 ppm
in the 31P NMR spectrum. This signal is highfield-shifted with
respect to that of free L1 (107 ppm), but this is not unusual for
coordinated phosphites.34 Furthermore, no significant shift was
observed for the phosphine oxide signal upon complexation,
hence ruling out bonding of the phosphoryl unit.
The related ligands L2, L3 and L4 were prepared by a method
similar to that outlined for L1, but starting from the mono-
functionalised cone-calixarenes 5,30 6 and 7,31 respectively (see
Experimental section). As for L1, the three 31P{1H} NMR
spectra show a phosphite signal near 106 ppm and the 1H
NMR spectra are in keeping with cone conformations. The IR
Reaction of L1 with [PtCl2(1,5-cyclooctadiene)] afforded
complex 9 in high yield. Its 31P NMR spectrum shows a singlet
at 32.7 ppm with the corresponding Pt satellites. The observed
J(PPt) coupling constant, 6736 Hz, is nearly identical to the
value (6629 Hz) recently reported by Pringle et al. for cis-
[PtCl2(paco-2Ј)] (2Ј is the non-butylated analogue of 2).23 An X-
ray diffraction study (vide infra) confirmed the cis stereo-
chemistry. Unlike that of L1, the 1H NMR spectrum of 9 shows
four distinct AB patterns for the bridging methylene units, as
well as an AB spectrum for the PCH2 protons, in keeping with
two calixarene subunits that are no longer Cs-symmetric. This
observation reflects the important steric crowding of the two
calixarene fragments, preventing the cis-arranged phosphites
freely rotating about the MP bonds. Fig. 2 shows the solid state
structure of the complex. The platinum centre has, as expected,
a planar coordination environment, the metal lying only ca.
0.010 Å out of the least-squares P2Cl2 plane. The PPtP angle
lies 6Њ over the ideal 90Њ value. The Pt–P bond lengths [2.218(2)
and 2.224(2) Å] are comparable to those found in other
[PtCl2(phosphite)2] complexes.35,36 Both calixarene cores adopt
a cone conformation, but are highly distorted with respect to
calix[4]arenes containing uncapped phenol units. Thus, as
spectrum of L2 displays a strong absorption band at 1760 cmϪ1
,
typical for an ester function, while the amide strech vibration of
L3 appears at 1653 cmϪ1
.
As already mentioned, the four calixarenes L1–L4 possess a
conical shape. Many studies have established that, for syn
ArCH2Ar arrangements, the 13C chemical shift of the
bridging methylene carbon lies between ca. 29 and 33 ppm, while
for an anti arrangement, the methylene signal appears in the
37–39 ppm region.31,32 Interestingly, for each of the four Cs-
symmetrical ligands described in this work, one ArCH2 signal
lies exactly between these two regions (near 36.5 ppm), while
the other one appears in the range expected for syn-arranged
ArCH2Ar moieties (ca. 33 ppm). The observation of a signal
with an ‘intermediate’ chemical shift may be interpreted in
terms of partial flattening of the calix core as a consequence of
the strain imposed by the very short µ3-P capping unit. Shape
modification of calixarenes through µ3-P caps has already been
described in detail, including for larger calixarenes.23,26,33 In
fact, the observed 31P chemical shifts, near 106 ppm, suggest
that calixarenes L1–L4 adopt a so-called up-up-out-up rather
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rotation of the ligands about their coordination axis generates
a cone having an opening angle (Ω) larger than 180Њ, hence
implying mutual steric hindrance between the phosphites.
Finally, we note that both calixarene cavities contain an
acetonitrile guest. This is not unusual with calix[4]arenes that
are somewhat flattened.37 The molecule crystallises with three
further CH3CN molecules as well as a water molecule.
Reaction of L1 with [PdCl2(1,5-cyclooctadiene)] yielded
complex trans-10 quantitatively. The assignment of a trans
stereochemistry was inferred from the NMR spectra which
show that the calixarene fragments retain a Cs-symmetrical
structure upon complexation. Obviously, owing to the large
separation between the two calixarene fragments, there is, in
this case, no barrier to rotation about the M–P bond.
Further examples where the ligand symmetry remains
unaffected upon complexation are the complexes 11–13,
obtained by reaction of [Pd(8-mq)Cl]2 (8-mqH = 8-methyl-
quinoline) with L1, L2 and L3, respectively, and complex 14
resulting from the reaction of L1 with the cyclometallated Pd()
complex [PdCl(o-C6H4CH2NMe2)]2.
Reaction of L2 with [PdCl(η3-C4H7)] afforded the allylic
complex 15. The metal plane is not a symmetry element of
this molecule, hence the corresponding 1H NMR spectrum
exhibits four distinct ArCH2Ar groups and an AB pattern for
the methylenic OCH2CO2Et protons.
Reaction of [Rh(acac)(CO)2] with one equiv. of L1–L3 gave
the highly soluble complexes 16, 17 and 18, respectively.
Phosphite bonding in these complexes was deduced from the
presence of a doublet in their 31P NMR spectra [J(PRh) =
ca. 305 Hz]. The corresponding IR spectra show a strong ν(CO)
carbonyl band near 2000 cmϪ1. The bis-phosphite 19 was
obtained in high yield by reaction of [RhCl(CO)2]2 with 4 equiv.
of L1. Characterisation data are reported in the Experimental
section. It is worth mentioning here that small amounts of 19
were formed in hydroformylation experiments (vide infra) when
using insufficiently purified samples of L1, i.e. containing
residual amounts of NEt3HCl.
In order to force bonding of the auxiliary groups, the three
complexes 11–13 were treated with silver tetrafluroborate
(eqn. 4). These reactions afforded the cationic complexes 20–22,
respectively, which were authenticated by elemental analysis
and mass and multinuclear NMR spectroscopies. Coordination
of the carbonyl functions of 21 and 22 was inferred from their
IR spectra. Thus, the ν(C᎐O) stretching vibrations of these two
᎐
complexes are lowered by more than 50 cmϪ1 when compared to
the corresponding starting complexes, 12 and 13, respectively.
In the 13P NMR spectrum of complex 20, the phosphine
oxide signal underwent a downfield shift of ca. 5 ppm upon
complexation, in accord with bonding of the phosphoryl
fragment. Owing to the presence of broad calixarene bands in
the ν(P᎐O) region, we were unable to confirm by IR the co-
᎐
ordination of the phosphoryl unit.
The ultimate proof for chelate formation in complex 22 came
from a single crystal X-ray diffraction study. The molecular
structure of the complex is shown in Fig. 3. Again, the calix-
arene core adopts an up-up-out-up cone conformation [‘out’
refers to the phenol ring bearing O(3)], but the deviation from
a typical cone is more pronounced than in 9, as revealed by
the dihedral angle of only 10Њ between the O(3) phenol ring and
the calix reference plane. The coordination plane is strongly
inclined with respect to the calix reference plane (dihedral angle
ca. 68Њ). All metal–ligand bond distances are normal, but, as
frequently observed in chelate complexes, the palladium stereo-
chemistry deviates somewhat from an ideal square planar
coordination geometry. Thus, the P–Pd–O angle is 7Њ greater
than 90Њ, reflecting the strain imposed on the P,O-chelate by
amide coordination. In fact, Pd–O bond formation forces the
amide plane to be nearly perpendicular to the coordination
plane, so as to optimise overlap of an oxygen lone pair with the
in-plane metal d-orbital. Incidently, the particular orientation
Fig.
2
Molecular structure of cis-[PtCl2(L1 )]. Each calixarene
contains an acetonitrile molecule (other solvents2 not shown). The But
groups have been ommitted for clarity. The most inclined phenol units
are those containing C(26) and C(83). Selected bond lengths (Å): Pt–
Cl(1) 2.342(1), Pt–Cl(2) 2.339(1), Pt–P(1) 2.217(1), Pt–P(3) 2.224(1)
anticipated, each calixarene contains an aryl–OP ring whose
orientation approaches that of the calixarene reference plane
[dihedral angles 26.2(2) and 27.9(3)Њ], resulting in an up-up-
out-up26 conformation (Fig. 2). The fact that rotation of a
particular phosphite about its Pt–P axis is hindered by the
neighbouring ligand becomes obvious if one considers the
spatial expansion of the ligands. The latter is particularly
important in the region containing the phosphine oxide arm.
For example, the P(1)–Pt–C(47) angle is 123Њ. Thus, virtual
J. Chem. Soc., Dalton Trans., 2002, 4264–4274
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and O(3) phenol rings equivalent on the NMR timescale. It
is noteworthy that equilibrating up-up-out-up/out-up-up-up con-
formations of calix[4]arenes have already been evidenced by
van Leeuwen et al.26 It appears very plausible that this fluxion-
ality induces the displacement of the amide arm from one side of
the coordination plane to the other. As verified by IR spectro-
scopy (in CH2Cl2 and CH3CN), there is no amide labilisation
during this process, ruling out hemilabile38 ligand behaviour.
Hydroformylation with heterodifunctional calix phosphites
In the present study, 1-octene was hydroformylated in toluene at
80 ЊC under 22 bar CO–H2 pressure (initial pressure at 80 ЊC).
The phosphite:metal:substrate ratio was 10:1:5000. The results
obtained for the four phosphites are summarised in Table 1 and
Fig. 4. It should be emphasised that these experiments were
Fig. 4 Conversion of 1-octene as a function of time using phosphites
L1–L4.
carried out with rigorously pure samples of phosphites, free of
NEt3HCl in particular. The presence of the latter in ligand
samples resulted in the formation of undesirable side products,
e.g. 19 (when starting from L1).
As expected for bulky phosphites, the reaction rates were
higher than those observed using P(OPh)3. The higher activity
is generally explained by a lower number of coordinated phos-
phites. The fastest catalysis occurred with the ether phosphite
L4. The corresponding activity (TOF ca. 4500) is, however,
1.6 times lower than that recently reported by van Leuwen et al.
Fig. 3 Molecular structure of the chelate complex 22. The calixarene
contains a CH2Cl2 guest. The O(3) atom is opposite to O(2). Selected
bond lengths (Å): Pd–N(1) 2.089(3), Pd–O(4) 2.148(3), Pd–P
2.2041(11).
of the amide induces an increased distortion of the calixarene
shape, as revealed by the strong inclination of the O(5) phenol
plane with respect to the calix reference plane (dihedral angle
ca. 80Њ vs. 61Њ for the O(1) phenol plane). Complex 22 displays
an apparent Cs symmetry in solution, in keeping with the
dynamics shown in Scheme 4, in which the chelate loop rapidly
i
for the related phosphite 23 bearing an Pr group instead of –
CH2CH2OMe. For comparison, the TOF found for PPh3 under
similar conditions is 2200 (L/B = 2.8), while the highest rates
reported to date were those for the bulky phosphite 24 (ca.
40000 mol RhϪ1 Ϫ1; L/B = 1.9).39 Interestingly, the activity
h
decreases in the order L4 > L1 > L2 > L3, that is, with
increasing donor strength of the oxygen-containing side group.
The aldehyde selectivity also changes significantly, those of
ligands L1–L3 being higher than those observed for 23 and L4.
The reason for these variations is a matter for discussion. A
logical explanation for an activity decrease is that confor-
mational changes within the calixarene backbone occur
during catalysis which incidently change the electronic and
steric properties of the ligand. Such a shape modification
appears, however, questionable since ligands 23 and L4 have
similar structures but different activities. Note in particular that
both ligands adopt an up-up-out-up conformation, at least
at room temperature.26 The observed changes could also arise
from the formation of P,O-chelate† complexes during catalysis.
Scheme 4 Swinging of the P–O(amide) loop from one side of the
metal plane to the other.
† Molecular mechanics calculations show that for a hypothetical
chelate complex [RhH(CO)2(P–O)] with tbp structure, the bisequatorial
P,O-coordination (ee) is favored over equatorial apical (ae) coordin-
ation.29 For this calculation, the calixarene was maintained in an up-up-
out-up conformation.
swings from one side of the metal plane to the other. This
motion implies restricted rotation of the two chelate ends about
the Pd–P and Pd–O(4) bonds, respectively, as well as a struc-
tural rearrangement of the calixarene core, rendering the O(2)
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Table 1 Hydroformylation of 1-octene with calixarene phosphitesa
Ligand
TOFb
L/Bc
L/all productsd (%)
Isomerisatione (%)
PPh3
P(OPh)3
Alkylphosphite 23
Ether phosphite L4
PV(O)-phosphite L1
Ester phosphite L2
Amide phosphite L3
2200
—
7300
4400
2450
1300
950
2.8
2.8f
1.4
1.4
2.4
3.6
2.7
1.5
—
6
3.5
11.2
9.6
13.6
54
53
58
57
57
a Conditions: L/Rh = 10, 1-octene/Rh = 5000, [Rh] = ca. 0.11 mM, initial pressure (at 20 ЊC) P = 20 bar CO–H2 (1:1), T = 80 ЊC, toluene–n-decane
(15 cm3, 0.5 cm3). b Turnover frequency, determined at ca. 30% conversion. c The L/B ratio takes into account all possible branched aldehydes.
d At ca. 95% conversion. e Isomerised 1-octene/all octenes. f At 40 bar. See also Experimental section.
Indeed, it should be recalled that, as shown by Lindner and
Norz, ether phosphines may act as transient chelate ligands
Experimental
when used in methanol carbonylation.17 Furthermore, Alper
et al. recently established that phosphine oxides may coordinate
to rhodium centres during olefin hydroformylation.40 Note that
the L/B variation (Table 1) does not rigorously parallel the
donor strength of the side group (ether < phosphine oxide <
ester < amide). The reason why ester L2 gives a higher L/B ratio
than amide L3 (the amide is a stronger donor than the ester
group) remains unclear and suggests that other factors (prob-
ably steric) have to be taken into account. At the end of the
catalytic runs performed with L1, the reaction mixture con-
tained, beside unmodified L1, trace amounts of compounds 3
and 4.
General procedures
Unless otherwise stated, materials were obtained from
commercial suppliers and used without further purification.
Solvents were dried over suitable reagents and freshly distilled
under dry nitrogen before use. CDCl3 was passed through a 5
cm thick alumina column and stored under N2 over molecular
sieves (4 Å). All reactions were carried out using modified
Schlenk tube techniques under a dry nitrogen atmosphere. IR
spectra were recorded on a Perkin-Elmer 1600 spectrometer
(4000–400 cmϪ1). Routine 1H, 13C{1H} and 31P{1H} NMR
spectra were recorded on Bruker AC-200 (1H: 200.1 MHz; 13C:
50.3 MHz), AC-300 (1H: 300.1 MHz; 31P: 121.5 MHz) and
ARX-500 (1H: 500.1 MHz) spectrometers. The 2D (1H–1H
NOESY and ROESY) NMR spectra were recorded on a
Bruker ARX-500 using a standard pulse sequence and Bruker
software for treatment of the acquired data. Proton chemical
shifts are reported relative to residual protiated solvents
(CHCl3, δ 7.26). The 13C chemical shifts are referenced relative
to deuterated solvents (CDCl3, δ 77.00) and the 31P NMR data
are given relative to external H3PO4. A positive sign denotes
a value downfield from the reference. Abbreviations used are
s = singlet, d = doublet, t = triplet, q = quartet, br = broad.
The mass spectra were recorded on a ZAB HF VG analytical
spectrometer using m-nitrobenzyl alcohol as a matrix. For
column chromatography, Geduran SI (E. Merck, 0.040–0.063
mm) was used. Routine thin layer chromatographic analyses
were carried out using plates coated with Merck Kieselgel
60 GF254. Elemental analyses were performed by the Service
de Microanalyse, Centre de Recherche Chimie, Université
Louis Pasteur, Strasbourg. Melting points were determined
with a Büchi 535 capillary melting point apparatus and are
uncorrected. The abbreviation 8-mq stands for the 8-methyl-
quinolinyl fragment.
Conclusion
In the present study we have described the high yield synthesis
of four new heterofunctionalised P,O-phosphites based on a
calix[4]arene backbone. The mixed phosphine oxide–phosphite
L1 is stable towards aqueous NaOH, but decomposes instantly
in the presence of slightly acidic water. All calixarenes adopt
a
cone conformation, making the phosphites potential
chelating systems. The ability to behave as a P,O-chelate was
unambiguously demonstrated for three of them, L1–L3, which
form 12-membered palladacycles with the ‘Pd(8-mq)ϩ’ unit.
In the latter complexes, the chelating P,O-loop swings from
one side of the metal plane to the other, the whole dynamics
possibly being facilitated by the flexibility of the calixarene.
In keeping with their steric crowding, the rates of hydrofor-
mylation for the ligands are higher than those observed for
P(OPh)3, but remain lower than that found for the bulky phos-
phite P{O(2-But,4-MeC6H3)}3. The activity decreases with the
donor strength of the oxo side group, suggesting that, during
catalysis, P,O-chelates are formed. Furthermore, with the
‘good’ O-donors, the L/B ratios are significantly higher than
with the ether phosphite L4. However, the observed selectivities
cannot be explained solely in terms of the donor properties of
the side group and further experiments, including IR studies
under CO/H2, with other heterofunctionalised phosphites
need to be performed to ascertain the reasons for these
observations.
Syntheses
5,11,17,23-Tetra-tert-butyl-25-(diphenylphosphinoyl-
methoxy)-26,27,28-(ꢀ3-phosphorustrioxy)calix[4]arene (L1). To
a cold (Ϫ40 ЊC) solution of 1 (1.000 g, 1.16 mmol) in a NEt3–
toluene mixture (2 cm3, 14.35 mmol NEt3; 100 cm3 toluene) was
added dropwise a solution of PCl3 (0.1 cm3, 1.16 mmol) in
toluene (5 cm3) maintained at ca. Ϫ40 ЊC. The mixture was then
heated at 80 ЊC for 20 h. The NEt3HCl salt formed was removed
by filtration, first through a bed of Celite, then through a 2 cm
layer of SiO2 and finally washed with cold toluene (2 × 10 cm3).
Filtration over SiO2 was required for complete removal of the
ammonium salt. The filtrate and washing solutions were evap-
orated under vacuum. Drying under vacuum for 2 h is sufficient
for complete removal of the remaining amine. Yield: 1.000 g,
1.12 mmol, 97%. Mp 105 ЊC. IR (KBr) νmax/cmϪ1: 1194 (s, P᎐O,
᎐
tentative assignment). 1H NMR (500 MHz, CDCl3): δ 8.11–8.07
4
and 7.45–7.37 [10 H, P(O)Ph2], 7.10 and 7.01 (AB q, J = 2.5,
2H each, m-ArH), 7.02 (s, 2H, m-ArH), 6.66 (s, 2H, m-ArH),
J. Chem. Soc., Dalton Trans., 2002, 4264–4274
4269

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4.58 [d, 2J = 7.7, 2H, P(O)CH2], 4.38 and 3.45 (AB q, 2J = 14.7,
4H, ArCH2Ar), 4.11 and 3.34 (AB q, 2J = 14.4 Hz, 4H,
ArCH2Ar), 1.36 [s, 18H, C(CH3)3], 1.16 [s, 9H, C(CH3)3], 0.86
[s, 9H, C(CH3)3]. 13C{1H} NMR (50 MHz, CDCl3): δ 153.38–
124.56 (aryl C), 73.48 [d, J(PC) 83 Hz, P(O)CH2], 36.42 (s × 2,
ArCH2Ar), 34.23 [s, C(CH3)3], 34.03 [s × 2, C(CH3)3], 33.86
[s, C(CH3)3], 33.11 (s × 2, ArCH2Ar), 31.42 [s × 3, C(CH3)3)],
30.94 [s, C(CH3)3]. 31P{1H} NMR (121 MHz, CDCl3): δ 107.0
[s, P(OAr)3], 26.1 [s, P(O)Ph2]. Found: C, 76.04; H, 7.44; calc.
for C57H64O5P2ؒH2O (Mr = 900.07): C, 76.06; H, 7.28%.
5,11,17,23-Tetra-tert-butyl-25-(ethoxycarbonylmethoxy)-
26,27,28-(ꢀ3-phosphorustrioxy)calix[4]arene (L2). PCl3 (0.17
cm3, 1.94 mmol) was added dropwise to a solution of 5 (1.420 g,
1.93 mmol) and NEt3 (2.0 cm3, 14.35 mmol) in toluene (100
cm3). The mixture was stirred at room temperature for 4 days.
The NEt3HCl salt formed was filtered off using a bed of Celite
and washed with toluene (2 × 10 cm3). The filtrate and washing
solutions were evaporated under vacuum. Analytically pure L2
was obtained as a white solid by recrystallisation from CH2Cl2–
methanol at Ϫ78 ЊC. Yield: 0.984 g, 1.29 mmol, 67%. Mp > 240
ЊC. IR (KBr) νmax/cmϪ1: 1760 (m s, C᎐O). 1H NMR (300 MHz,
᎐
Racemic mixture of 5,11,17,23-tetra-tert-butyl-25-(diphenyl-
phosphinoylmethoxy)-(ꢀ2-26,27-phosphonato)-28-hydroxycalix-
[4]arene and 5,11,17,23-tetra-tert-butyl-25-(diphenylphosphino-
ylmethoxy)-26-hydroxy-(ꢀ2-27,28-phosphonato)calix[4]arene
(3). A solution of L1 (1.000 g, 1.13 mmol) in CH2Cl2 (20 cm3)
was shaken in the presence of a 0.1 M solution of NH4Cl
in water (20 cm3). After 0.5 h, the organic component was sep-
arated and washed twice with water (2 × 10 cm3). The organic
phase was then dried over MgSO4. After filtration, the solution
was evapored to dryness. Recrystallisation from CH2Cl2–
pentane at Ϫ78 ЊC afforded 3 as a white, analytically pure solid.
CDCl3): δ 7.17–7.10 (m, 4H, m-ArH), 7.04 (s, 2H, m-ArH),
6.77 (s, 2H, m-ArH), 4.73 and 3.56 (AB q, 2J = 14.4, 4H,
ArCH2Ar), 4.56 (s, 2H, OCH2CO2), 4.39 and 3.44 (AB q,
2J = 14.3, 4H, ArCH2Ar), 4.25 (q, 3J = 7.1, 2H, CH2CH3), 1.36
3
[s, 18H, C(CH3)3], 1.30 (t, J = 7.1 Hz, 3H, CH2CH3), 1.19 [s,
9H, C(CH3)3], 0.94 [s, 9H, C(CH3)3]. 13C{1H} NMR (50 MHz,
CDCl3): δ 169.44 (s, CO2), 148.13–124.60 (aryl C), 72.04 (s,
OCH2CO2), 61.00 (s, CH2CH3), 36.57 (s × 2, ArCH2Ar), 34.32
[s, C(CH3)3], 34.09 [s × 2, C(CH3)3], 33.99 [s, C(CH3)3], 33.86
[s, C(CH3)3], 33.86 (s × 2, ArCH2Ar), 31.51 [s × 3, C(CH3)3)],
31.14 [s, C(CH3)3], 14.29 (s, CH2CH3); 31P{1H} NMR (121
MHz, CDCl3): δ 106.3 [s, P(OAr)3]. Found: C, 75.61; H, 7.88;
calc. for C48H59O6P (Mr = 762.95): C, 75.56; H, 7.79%.
Yield: 0.803 g, 0.88 mmol, 78%. Mp 175–182 ЊC. IR (KBr) νmax
/
1
cmϪ1: 1194 (P᎐O, tentative assignment). H NMR (500 MHz,
᎐
CDCl3): δ 8.00–7.93, 7.83–7.77 and 7.64–7.33 [10H, P(O)Ph2],
7.27 and 7.16 (AB q, 4J = 2.2, 2H, m-ArH), 7.14 and 7.08 (AB q,
5,11,17,23-Tetra-tert-butyl-25-(diethylcarbamoylmethoxy)-
26,27,28-trihydroxycalix[4]arene (6). A suspension of p-tert-
butylcalix[4]arene (1.000 g, 1.54 mmol) and K2CO3 (0.115 g,
0.83 mmol) in acetonitrile (50 cm3) was refluxed for 2 h.
2-Bromo-N,N-diethylacetamide (1.000 g, 5.15 mmol) was then
added and the mixture refluxed for a further 10 days. After
cooling, the solvent was removed under reduced pressure. The
residue was taken up in CH2Cl2 (30 cm3) and washed with 1 M
HCl (30 cm3), then with water (30 cm3). The organic layer was
dried over MgSO4, filtered and evaporated. The crude product
was purified by column chromatography using AcOEt–hexane
(30:70, v/v) as eluent. Unreacted p-tert-butylcalix[4]arene eluted
first followed by 6 (SiO2, Rf = 0.38, AcOEt–hexane, 30:70,
v/v). After evaporation, the residue was taken up in CH2Cl2.
Addition of ethanol at Ϫ78 ЊC afforded the product as a white
powder. Yield: 0.274 g, 0.36 mmol, 23%. Mp 149 ЊC. IR (KBr)
νmax/cmϪ1: 1653 (s, C᎐O). 1H NMR (300 MHz, CDCl ): δ 10.43
4
4J = 2.0, 2H, m-ArH), 7.02 and 6.42 (AB q, J = 2.2, 2H, m-
4
ArH), 6.82 and 6.77 (AB q, J = 2.4, 2H, m-ArH), 6.01 [d,
J(PH) 792, 1H, P(OAr)2(O)H], 5.27 (s, 1H, OH, exchanges with
D2O), 4.79 and 4.60 [ABX system with X = P, 2JAB = 13.2, 2JAX
=
7.6, 2JBX = 0, 2H, P(O)CH2], 4.47 and 3.45 (AB q, 2J = 14.7, 2H,
ArCH2Ar), 4.25 and 3.54 (AB q, 2J = 14.0, 2H, ArCH2Ar), 4.20
and 3.50 (AB q, 2J = 14.0, 2H, ArCH2Ar), 4.16 and 3.22 (AB q,
2J = 14.4 Hz, 2H, ArCH2Ar), 1.33 [s, 9H, C(CH3)3], 1.25 [s, 9H,
C(CH3)3], 1.06 [s, 9H, C(CH3)3], 0.84 [s, 9H, C(CH3)3]. 13C{1H}
NMR (50 MHz, CDCl3): δ 152.98–125.06 (aryl C), 73.92
[d, J(PC) = 82 Hz, P(O)CH2], 35.83 (s × 2, ArCH2Ar), 34.19
[s, C(CH3)3], 34.03 (s, ArCH2Ar), 33.93, 33.83, 33.76 [s × 3,
C(CH3)3], 33.53 (s, ArCH2Ar), 31.60, 31.40, 31.11, 30.79 [s × 4,
C(CH3)3)]. 31P{1H} NMR (121 MHz, CDCl3): δ 25.8 [s, P(O)-
Ph2], 1.4 [s, P(OAr)2(O)H]. 31P NMR (121 MHz, CDCl3): δ 25.9
[br s, P(O)Ph2], 1.4 [d, J(PH) 792 Hz, P(OAr)2(O)H]. Found:
C, 75.12; H, 7.48; calc. for C57H64O6P2 (Mr = 909.08): C, 75.31;
H, 7.44%.
᎐
3
(s, 1H, OH, exchanges with D2O), 9.73 (s, 2H, OH, exchanges
with D2O), 7.08 (s, 2H, m-ArH), 7.04 (m, 4H, m-ArH), 6.95
4
(d, J = 2.4, 2H, m-ArH), 4.96 (s, 2H, OCH2), 4.60 and 3.37
5,11,17,23-Tetra-tert-butyl-25-(diphenylphosphinoylmeth-
(AB q, 2J = 12.9, 4H, ArCH2Ar), 4.34 and 3.40 (AB q, 2J = 13.6,
4H, ArCH2Ar), 3.55 (q, 3J = 7.2, 2H, NCH2CH3), 3.29 (q, 3J =
7 Hz, 2H, NCH2CH3), 1.29–1.20 [overlapping signals, 42H,
C(CH3)3 and NCH2CH3]; 13C{1H} NMR (50 MHz, CDCl3):
oxy)-26,27,28-(ꢀ3-phosphato)calix[4]arene (4).
A
CH2Cl2–
ethanol solution (1:1, v/v, 50 cm3) of L1 (3.000 g, 3.37 mmol)
was left standing in air for 4 days. The solvent was then evapor-
ated and the residue was subjected to flash chromatography
using AcOEt–hexane (40:60, v/v) as eluent. Unreacted L1 eluted
first (Rf = 0.50, AcOEt–hexane, 40:60, v/v) followed by 4 (Rf =
0.30, AcOEt–hexane, 40:60, v/v). Analytically pure 4 (white
solid) was obtained by recrystallisation in CH2Cl2–pentane.
δ 168.85 (s, C᎐O), 148.31, 142.76, 134.03, 127.95 (s × 4,
᎐
aromatic Cquat), 126.34–125.61 (aryl C), 72.26 (s, OCH2CO),
40.68 and 40.42 (s × 2, CH2CH3), 33.96 [s, C(CH3)3], 33.16 (s ×
2, ArCH2Ar), 32.94 (s × 2, ArCH2Ar), 31.50 [s, C(CH3)3)],
31.33 [s, C(CH3)3], 14.06 and 12.94 (s × 2, CH2CH3). Only one
C(CH3)3 signal could be detected. Found: C, 78.71; H, 8.83;
N, 1.77; calc. for C50H67NO5 (Mr = 762.07): C, 78.80; H, 8.86;
N, 1.84%.
Yield: 0.600 g, 0.66 mmol, 19%. Mp > 240 ЊC. IR (KBr) νmax
/
cmϪ1: 1307 (s, P᎐O
), 1187 (s, P᎐O
oxide, tentative
᎐
᎐
phosphate
phosphine
1
assignment). H NMR (300 MHz, CDCl3): δ 8.37–8.31 and
7.50–7.48 [10 H, P(O)Ph2], 7.10 and 7.06 (AB q, 4J = 2.2,
4H, m-ArH), 7.06 (s, 2H, m-ArH), 6.48 (s, 2H, m-ArH), 4.55 [d,
5,11,17,23-Tetra-tert-butyl-25-(diethylcarbamoylmethoxy)-
26,27,28-(ꢀ3-phosphorustrioxy)calix[4]arene (L3). To a solution
of 6 (0.611 g, 0.802 mmol) in an NEt3–toluene mixture (NEt3,
1 cm3, 7.17 mmol; toluene, 50 cm3) was added dropwise PCl3
(0.070 cm3, 0.802 mmol) under stirring. After 3 h, the NEt3HCl
salt formed was removed by filtration through a bed of Celite
and washed with toluene (2 × 15 cm3). The filtrate and washing
solutions were evaporated under vacuum. Yield: 0.620 g,
2J = 7.7, 2H, P(O)CH2], 4.53 and 3.51 (AB q, J = 14.6, 4H,
2
ArCH2Ar), 4.24 and 3.27 (AB q, 2J = 14.8 Hz, 4H, ArCH2Ar),
1.35 [s, 18H, C(CH3)3], 1.15 [s, 9H, C(CH3)3], 0.71 [s, 9H,
C(CH3)3]. 13C{1H} NMR (50 MHz, CDCl3): δ 155.11–124.72
(aryl C), 74.08 [d, J(PC) 84 Hz, P(O)CH2], 35.36 (s × 2,
ArCH2Ar), 34.38 [s, C(CH3)3], 34.16 [s × 2, C(CH3)3], 33.76
[s, C(CH3)3], 32.31 (s × 2, ArCH2Ar), 31.36 [s × 3, C(CH3)3)],
30.82 [s, C(CH3)3]. 31P{1H} NMR (121 MHz, CDCl3):
0.79 mmol, 98%. Mp 88–90 ЊC. IR (KBr) νmax/cmϪ1: 1653 (s, C᎐
᎐
δ
24.9 [s, P(O)Ph2], Ϫ23.3 [s, P(O)(OAr)3]. Found: C,
O). 1H NMR (300 MHz, CDCl3): δ 7.16 (m, 2H, m-ArH), 7.09
75.67; H, 7.35; calc. for C57H64O6P2 (Mr = 907.06): C, 75.48;
H, 7.11%.
(d, 4J = 2.5 Hz, 2H, m-ArH), 7.04 (s, 2H, m-ArH), 6.77 (s, 2H,
2
m-ArH), 4.64 and 3.43 (AB q, J = 14.1, 2H each, ArCH2Ar),
4270
J. Chem. Soc., Dalton Trans., 2002, 4264–4274

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2
4.55 (s, 2H, OCH2), 4.39 and 3.56 (AB q, J = 14.3, 2H each,
under vacuum. Addition of pentane and cooling to Ϫ20 ЊC
ArCH2Ar), 3.58 (q, 3J = 6.9, 2H, NCH2CH3), 3.45 (q, 3J = 7.1,
2H, NCH2CH3), 1.35 [s, 18H, C(CH3)3], 1.24 (t, J = 6.9, 3H,
afforded 9 as a white solid. Yield: 0.130 g, 0.06 mmol, 79%. Mp
3
> 240 ЊC. IR (KBr) νmax/cmϪ1: 1179.2 (P᎐O, tentative assign-
᎐
3
NCH2CH3), 1.18 [s, 9H, C(CH3)3], 1.17 (t, J = 6.9 Hz, 3H,
ment). 1H NMR (300 MHz, CDCl3): δ 7.89–7.68 and 7.46–7.31
[20 H, P(O)Ph2], 7.06–6.98 (6H, m-ArH), 6.91 (4H, m-ArH),
6.70 (s, 2H, m-ArH), 6.57 (s, 2H, m-ArH), 6.45 (s, 2H, m-ArH),
NCH2CH3), 0.95 [s, 9H, C(CH3)3]. 13C{1H} NMR (75 MHz,
CDCl ): δ 167.15 (s, C᎐O), 155.43–124.54 (aryl C), 74.36
᎐
3
2
2
(s, OCH2CO), 41.54 and 39.90 (s × 2, CH2CH3), 36.49 (s × 2,
ArCH2Ar), 34.23, 34.00 and 33.90 [s × 3, C(CH3)3], 33.82 (s ×
2, ArCH2Ar), 31.40 and 31.06 [s × 2, C(CH3)3], 14.40 and 12.83
(s × 2, CH2CH3). 31P{1H} NMR (121 MHz, CDCl3): δ 106.1
[s, P(OAr)3]. Found: C, 76.22; H, 8.65; N, 1.51; calc. for
C50H64NO5P (Mr = 790.02): C, 76.02; H, 8.17; N, 1.77%.
5.78 and 5.54 [ABX system with X = P, JAB = 12.9, JAX = 0,
2JBX = 6.5, 4H, P(O)CH2], 4.89 and 3.34 (AB q, J = 12.8, 4H,
2
ArCH2Ar), 4.60 and 3.22 (AB q, 2J = 13.9, 4H, ArCH2Ar), 4.60
and 2.90 (AB q, 2J = 12.8, 4H, ArCH2Ar), 3.98 and 2.49 (AB q,
2J = 12.2 Hz, 4H, ArCH2Ar), 1.28 [s, 18H, C(CH3)3], 1.23 [s,
18H, C(CH3)3], 1.20 [s, 18H, C(CH3)3], 0.96 [s, 18H, C(CH3)3].
13C{1H} NMR (50 MHz, CDCl3): δ 150.75–124.07 (aryl C),
71.69 [d, J(PC) = 72.6 Hz, P(O)CH2], 37.76 (s, ArCH2Ar), 35.40
[s, C(CH3)3], 34.81 [s, C(CH3)3], 33.27 (s, ArCH2Ar), 32.27
[s, C(CH3)3], 32.07 [s, C(CH3)3]. 31P{1H} NMR (121 MHz,
CDCl3): δ 32.7 [s with Pt satellites, J(PPt) = 6736 Hz, P(OAr)3],
5,11,17,23-Tetra-tert-butyl-25-(3-oxabutyloxy)-26,27,28-
(ꢀ3-phosphorustrioxy)calix[4]arene (L4). PCl3 (0.027 cm3, 0.31
mmol) was added dropwise to a toluene (100 cm3) solution con-
taining 7 (0.217 g, 0.31 mmol) and NEt3 (0.5 cm3, 3.59 mmol).
The mixture was stirred at room temperature for 18 h. The
NEt3HCl salt formed was filtered off using a bed of Celite and
washed with toluene (2 × 10 cm3). The filtrate and washing
solutions were evaporated under vacuum. Yield: 0.194 g, 0.264
mmol, 86%. Mp 91–92 ЊC. 1H NMR (200 MHz, CDCl3): δ 7.18
and 7.11 (AB q, 4J = 2.2 Hz, 4H, m-ArH), 7.06 (s, 2H, m-ArH),
6.80 (s, 2H, m-ArH), 4.67 and 3.52 (AB q, 2J = 14.5, 4H,
ArCH2Ar), 4.45 and 3.48 (AB q, 2J = 14.3 Hz, 4H, ArCH2Ar),
4.03 (m, 2H, OCH2), 3.78 (m, 2H, OCH2), 3.47 (s, 3H, OCH3),
1.51 [s, 18H, C(CH3)3], 1.20 [s, 9H, C(CH3)3], 0.98 [s, 9H,
C(CH3)3]. 13C{1H} NMR (50 MHz, CDCl3): δ 152.22–143.00
and 134.15–124.40 (aryl C), 74.26 (s, OCH2), 71.67 (s, OCH2),
59.39 (s, OCH3), 36.56 (s × 2, ArCH2Ar), 34.27 [s, C(CH3)3],
34.04 [s, C(CH3)3], 33.62 (s × 2, ArCH2Ar), 31.47 [s × 3,
C(CH3)3], 31.17 [s, C(CH3)3]. 31P{1H} NMR (121 MHz,
CDCl3): δ 105.6 [s, P(OAr)3]. Found: C, 76.95; H, 8.24; calc. for
C47H59O5P (Mr = 734.942): C, 76.81; H, 8.09%.
26.5 [s, P(O)Ph2]. Found: C, 66.70; H, 6.52; calc. for C114
-
H128Cl2O10P4Pt (Mr = 2048.11): C, 66.85; H, 6.30%.
trans-Dichlorobis{5,11,17,23-tetra-tert-butyl-25-(diphenyl-
phosphinoylmethoxy-26,27,28-(ꢀ3-phosphorustrioxy)calix[4]-
arene}palladium(II) (10). L1 (0.150 g, 0.168 mmol) was added to
a solution of [PdCl2(1,5-cyclooctadiene)] (0.024 g, 0.08 mmol)
in CH2Cl2 (15 cm3). After stirring for 1 h, the solution was
concentrated under vacuum. Addition of pentane and cooling
to Ϫ20 ЊC afforded 10 as a pale yellow solid. Yield: 0.224 g,
0.11 mmol, 68%. Mp > 240 ЊC. IR (KBr) νmax/cmϪ1: 1183.1
(P᎐O, tentative assignment). 1H NMR (300 MHz, CDCl3):
᎐
δ 7.90–7.84 and 7.23–7.18 [20 H, P(O)Ph2], 7.05 (s, 4H, m-ArH),
7.00 (d, 4J = 2.9, 4H, m-ArH), 6.93 (s, 4H, m-ArH), 6.60 (s, 4H,
m-ArH), 5.56 [s, 4H, P(O)CH2], 4.82 and 3.26 (AB q, 2J = 14.1,
2H, ArCH2Ar), 4.45 and 3.18 (AB q, 2J = 14.3 Hz, 2H,
ArCH2Ar), 1.28 [s, 36H, C(CH3)3], 1.20 [s, 18H, C(CH3)3], 0.93
[s, 18H, C(CH3)3]. 13C{1H} NMR (50 MHz, CDCl3): δ 146.43–
124.63 (aryl C), 72.88 [d, J(PC) = 74 Hz, P(O)CH2], 36.42
(s, ArCH2Ar), 35.66 [s, C(CH3)3], 34.45 [s, C(CH3)3], 33.99 [s,
C(CH3)3], 33.83 [s, ArCH2Ar], 31.40 [s × 3, C(CH3)3], 31.17
[s, C(CH3)3]. 31P{1H} NMR (121 MHz, CDCl3): δ 58.8 [s,
P(OAr)3], 27.6 [s, P(O)Ph2]. Found: C, 69.56; H, 6.58; calc. for
C114H128Cl2O10P4Pd (Mr = 1959.45): C, 69.88; H, 6.58%.
(ꢁ6-p-Cymene)dichloro{5,11,17,23-tetra-tert-butyl-25-(di-
phenylphosphinoylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)-
calix[4]arene}ruthenium(II) (8). L1 (0.250 g, 0.28 mmol) was
added to a solution of [RuCl2(p-cymene)]2 (0.086 g, 0.14 mmol)
in CH2Cl2 (40 cm3). After stirring for 2 h, the solvent was
removed under vacuum. Recrystallisation from AcOEt–
hexane. Yield: 0.190 g, 0.16 mmol, 57%. Mp 219–223 ЊC (slow
decomp.). IR (KBr) νmax/cmϪ1: 1195 (P᎐O, tentative assign-
Chloro(8-methylquinolinylmethyl-C,N){5,11,17,23-tetra-tert-
butyl-25-(diphenylphosphinoylmethoxy)-26,27,28-(ꢀ3-phos
phorustrioxy)calix[4]arene}palladium(II) (11). L1 (0.151 g,
0.169 mmol) was added to a solution of [Pd(8-mq)Cl]2 (0.048 g,
0.08 mmol) in CH2Cl2 (15 cm3). After stirring for 1 h, the
solution was concentrated under vacuum. Addition of pentane
and cooling to Ϫ20 ЊC afforded 11 as a pale yellow solid. Yield:
0.160 g, 0.136 mmol, 60%. Mp > 168–169 ЊC (decomp). IR
᎐
ment). 1H NMR (300 MHz, CDCl3): δ 7.78–7.71 and 7.52–7.42
[10 H, P(O)Ph2], 7.10 (s, 2H, m-ArH), 7.05 (s, 2H, m-ArH), 6.88
(s, 2H, m-ArH), 6.21 (s, 2H, m-ArH), 5.82 and 5.70 (AA’BB’
3
system, J = 5.9, 2H each, C6H4 of p-cymene), 4.90 and 3.50
(AB q, J = 14.3, 2H each, ArCH2Ar), 4.82 [s, 2H, P(O)CH2],
2
4.76 and 3.23 (AB q, 2J = 15, 2H each, ArCH2Ar), 2.76 [m, 1H,
CH(CH3)2 of p-cymene], 1.80 (s, 3H, ArCH3 of p-cymene), 1.33
[s × 2, 18H, C(CH3)3], 1.13 [s, 9H, C(CH3)3], 1.05 [d, 3J = 6.9 Hz,
6H, CH(CH3)2 of p-cymene], 0.59 [s, 9H, C(CH3)3]. 13C{1H}
NMR (50 MHz, CDCl3): δ 148.29–123.87 (aryl C), 108.99
and 96.54 (s × 2, Cquat of p-cymene), 91.69, 91.56, 87.33 and
87.16 (s × 4, aryl CH of p-cymene), 73.28 [d, J(PC) = 80.3 Hz,
P(O)CH2], 35.99 (s, ArCH2Ar), 34.16 [s, C(CH3)3], 33.80 [s,
C(CH3)3], 33.27 (s, ArCH2Ar), 31.31 [s, C(CH3)3)], 31.21 [s × 2,
C(CH3)3)], 30.74 [s, C(CH3)3], 21.27 [s, CH(CH3)2 of p-
cymene], 17.93 (s, ArCH3 of p-cymene). 31P{1H} NMR (121
MHz, CDCl3): δ 92.56 [s, P(OAr)3], 24.75 [s, P(O)Ph2]. Found:
C, 67.47; H, 7.64; calc. for C67H78Cl2O5P2Ru (Mr = 1197.29): C,
67.21; H, 6.57%. Despite several purifications (recrystallisation
followed by chromatography), the samples always contained
free p-cymene.
(KBr) νmax/cmϪ1: 1187.3 (P᎐O, tentative assignment). 1H NMR
᎐
(200 MHz, CDCl3): δ 9.60–9.54 (1H, arom. H of 8-mq), 8.31–
8.26 (1H, arom H of 8-mq), 7.65–7.43 and 7.13–6.99 [20 H,
P(O)Ph2, arom. H of 8-mq and m-ArH of calix], 6.51 (s, 2H,
m-ArH), 4.95 [d, 2J = 1.7, 2H, P(O)CH2], 4.82 and 3.45 (AB q,
2J = 14, 4H, ArCH2Ar), 4.65 and 3.41 (AB q, 2J = 14.1 Hz, 4H,
ArCH2Ar), 1.36 [s, 18H, C(CH3)3], 1.18 [s, 9H, C(CH3)3], 0.82
[s, 9H, C(CH3)3]. 13C{1H} NMR (50 MHz, CDCl3): δ 154.16–
121.09 (aryl C), 72.82 [d, J(PC) = 80 Hz, P(O)CH2], 35.99 (s × 2,
ArCH2Ar), 34.35 [s, C(CH3)3], 34.03 [s, C(CH3)3], 33.70 (s × 2,
ArCH2Ar), 31.40 [s, C(CH3)3], 31.01 [s, C(CH3)3], 26.39
(s, CH2 8-mq); 31P{1H} NMR (121 MHz, CDCl3): δ 89.8 [s,
P(OAr)3], 26.3 [s, P(O)Ph2]. Found: C, 64.52; H, 6.17; calc. for
C67H72ClNO5P2Pd.CH2Cl2 (Mr = 1260.04): C, 64.82; H, 6.17%.
cis-Dichlorobis{5,11,17,23-tetra-tert-butyl-25-(diphenylphos-
phinoylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)calix[4]arene}-
platinum(II) (9). L1 (0.143 g, 0.16 mmol) was added to a solution
of [PtCl2(1,5-cyclooctadiene)] (0.030 g, 0.08 mmol) in CH2Cl2
(30 cm3). After stirring for 1 h, the solution was concentrated
Chloro(8-methylquinolinylmethyl-C,N){5,11,17,23-tetra-tert-
butyl-25-(ethoxycarbonylmethoxy)-26,27,28-(ꢀ3-phosphorustri-
oxy)calix[4]arene}palladium(II) (12). L2 (0.175 g, 0.23 mmol)
was added to a solution of [Pd(8-mq)Cl]2 (0.065 g, 0.114 mmol)
in CH2Cl2 (50 cm3). After stirring for 24 h, the solution was
J. Chem. Soc., Dalton Trans., 2002, 4264–4274
4271

View Article Online
concentrated under vacuum. Addition of MeOH and cooling
to Ϫ78 ЊC afforded 12 as a pale yellow solid. Yield: 0.163 g,
0.156 mmol, 68%. Mp > 240 ЊC. IR (CH2Cl2) νmax/cmϪ1: 1755
(C᎐O). 1H NMR (300 MHz, CDCl ): δ 9.64–9.60 (m, 1H, arom.
Chloro(ꢁ3-2-methylallyl){5,11,17,23-tetra-tert-butyl-25-
(ethoxycarbonylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)-
calix[4]arene}palladium(II) (15). L2 (0.186 g, 0.244 mmol) was
added to a solution of [Pd(η3-C4H7)Cl]2 (0.048 g, 0.12 mmol)
in CH2Cl2 (10 cm3). After stirring for 15 h, the solution was
concentrated to ca. 50%. Addition of hexane and cooling to
Ϫ78 ЊC gave 15 as a white powder. Yield: 0.160 g, 0.167 mmol,
᎐
3
H of 8-mq), 8.28 (d, 3J = 7.1, 1H, arom. H of 8-mq), 7.61–7.44
(m, 4H, arom. H of 8-mq), 7.21–7.05 (m, 6H, m-ArH), 6.77 (s,
2
2H, m-ArH), 5.07 and 3.54 (AB q, J = 13.9, 4H, ArCH2Ar),
2
4.71 and 3.49 (AB q, J = 14.0, 4H, ArCH2Ar), 4.71 (s, 2H,
68%. Mp > 240 ЊC. IR (nujol) νmax/cmϪ1: 1734 (C᎐O). 1H NMR
᎐
OCH2CO2), 3.84 (s, 2H, CH2 of 8-mq), 3.66 (q, 3J = 7.2 Hz, 2H,
CH2CH3), 1.36 [s, 18H, C(CH3)3], 1.22 [s, 9H, C(CH3)3], 0.96
(400 MHz, CDCl3): δ 7.22–7.19 and 7.11–7.10 (2 overlapping
AB q, 4H, m-ArH), 7.07 (s, 2H, m-ArH), 6.73 and 6.71 (AB q,
3
2
[s, 9H, C(CH3)3], 0.88 (t, J = 7.1 Hz, 3H, CH2CH3); 13C{1H}
2H, m-ArH), 5.01 and 3.54 (AB q, J = 14.4, 2H, ArCH2Ar),
2
NMR (50 MHz, CDCl3): δ 169.77 (s, CO), 153.25–121.19
(aryl C), 71.62 (s, OCH2CO2), 60.25 (s, CH2CH3), 36.12 (s,
ArCH2Ar), 34.42 [s, C(CH3)3], 34.12 [s, ArCH2Ar and
C(CH3)3], 33.93 [s × 2, C(CH3)3], 31.40 [s × 3, C(CH3)3], 31.11
[s, C(CH3)3], 13.80 (s, CH2CH3), the CH2 signal of 8-mq was
not detected. 31P{1H} NMR (121 MHz, CDCl3): δ 88.7 [s,
P(OAr)3]. Found: C, 66.80; H, 6.43; N, 1.42; calc. for
C58H67ClNO6PPd (Mr = 1047.00): C, 66.53; H, 6.45; N, 1.34%.
5.00 and 4.72 (AB q, J = 16.4, 2H, OCH2CO2), 4.93 and 3.56
(AB q, 2J = 15.0, 2H, ArCH2Ar), 4.45 and 3.46 (AB q, 2J = 13.6,
2H, ArCH2Ar), 4.43 (br s, 1H, H-allyl), 4.41 and 3.49 (AB q,
2J = 13.2, 2H, ArCH2Ar), 4.14 (q, 3J = 7.2, 2H, OCH2CH3), 3.47
(br s, 1H, H-allyl), 3.16 (br s, 1H, H-allyl), 2.55 (br s, 1H,
H-allyl), 1.85 (s, 3H, CH3-allyl), 1.37 [s, 9H, C(CH3)3], 1.36 [s,
3
9H, C(CH3)3], 1.25 (t, J = 7.2 Hz, OCH2CH3), 1.18 [s, 9H,
C(CH3)3], 0.90 [s, 9H, C(CH3)3]; 13C{1H} NMR (50 MHz,
CDCl3): δ 170.73 (s, CO2), 153.77–124.60 (aryl C and Cquat
-
Chloro(8-methylquinolinylmethyl-C,N){5,11,17,23-tetra-tert-
butyl-25-(diethylcarbamoylmethoxy)-26,27,28-(ꢀ3-phosphorus-
trioxy)calix[4]arene}palladium(II) (13). L3 (0.175 g, 0.22 mmol)
was added to a solution of [Pd(8-mq)Cl]2 (0.063 g, 0.111 mmol)
in CH2Cl2 (20 cm3). After stirring for 24 h, the solution was
concentrated under vacuum. Addition of hexane and cooling to
Ϫ78 ЊC afforded 13 as a pale yellow solid. Yield: 0.170 g, 0.158
allyl), 78.62 and 77.54 (s × 2, CH2-allyl), 71.95 (s, OCH2CO2),
60.73 (s, OCH2CH3), 36.31 and 35.99 (s × 2, ArCH2Ar), 34.45
[s × 2, C(CH3)3], 34.18 [s × 2, C(CH3)3], 33.98 (s × 2,
ArCH2Ar), 31.49 [s × 3, C(CH3)3], 31.11 [s, C(CH3)3], 23.27 (s,
CH3-allyl), 14.24 (s, OCH2CH3); 31P{1H} NMR (121 MHz,
CDCl3): δ 107.0 [s, P(OAr)3]. Found: C, 67.23; H, 7.10; calc. for
C52H66ClO6PPd (Mr = 959.92): C, 67.06; H, 6.93%.
mmol, 71%. Mp > 233 ЊC (decomp.). IR (CH2Cl2) νmax/cmϪ1
:
1655 (C᎐O). 1H NMR (300 MHz, CDCl ): δ 9.66–9.62 (m, 1H,
Acetylacetonatocarbonyl{5,11,17,23-tetra-tert-butyl-25-(di-
᎐
3
arom. H of 8-mq), 8.29–8.26 (m, 1H, arom. H of 8-mq), 7.61–
7.44 (m, 4H, arom. H of 8-mq), 7.20 (br s, 2H, m-ArH), 7.12
(s, 2H, m-ArH), 7.10 (s, 2H, m-ArH), 6.75 (s, 2H, m-ArH), 5.10
phenylphosphinoylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)-
calix[4]arene}rhodium(I) (16). L1 (0.134 g, 0.15 mmol) was
added‡ to a solution of [Rh(acac)(CO)2] [acac = MeC(O)-
CHC(O)Me] (0.040 g, 0.151 mmol) in CH2Cl2 (30 cm3). After
stirring for 12 h, the volatiles were evaporated under vacuum to
give 16 as a yellow powder. Owing to its high solubility in all
common organic solvents, 16 was not purified further. Yield:
2
and 3.56 (AB q, J = 13.9, 4H, ArCH2Ar), 4.79 (s, 2H, OCH2-
CON), 4.70 and 3.49 (AB q, 2J = 14.0, 4H, ArCH2Ar), 3.82 (s,
3
3
2H, CH2Pd), 3.07 (q, J = 7.1, 2H, CH2CH3), 2.87 (q, J = 7.1
Hz, 2H, CH2CH3), 1.36 [s, 18H, C(CH3)3], 1.21 [s, 9H,
C(CH3)3], 0.95 [s, 9H, C(CH3)3], 0.67 (t, 3J = 7.1 Hz, 3H,
0.156 g, 0.139 mmol, 92%. Mp 76–78 ЊC. IR (CH2
Cl ) ν
/
2
max
cmϪ1: 2004s (CO), 1182 (s, P᎐O, tentative assignment). 1H
3
CH2CH3), 0.48 (t, J = 7.1 Hz, 3H, CH2CH3). 13C{1H} NMR
᎐
NMR (300 MHz, CDCl3): δ 8.00–7.93 and 7.53–7.44 [10 H,
P(O)Ph2], 7.05 (s, 4H, m-ArH), 7.02 (s, 2H, m-ArH), 6.35 (s, 2H,
m-ArH), 5.37 (s, 1H, CH-acac), 4.79 [d, 2J = 4.4, 2H, P(O)CH2],
(50 MHz, CDCl3): δ 167.64 (s, CO), 153.71–121.19 (aryl C),
72.86 (s, OCH2), 41.35 and 39.89 (s × 2, CH2CH3), 36.16 (s,
ArCH2Ar), 34.45 [s, C(CH3)3], 34.31 (s, ArCH2Ar), 34.10 [s ×
2, C(CH3)3], 33.93 [s, C(CH3)3], 31.48 [s × 3, C(CH3)3], 31.15
[s, C(CH3)3], 27.12 (s, CH2 of 8-mq), 13.77 and 12.61 (s × 2,
CH2CH3); 31P{1H} NMR (121 MHz, CDCl3): δ 88.1 [s,
P(OAr)3]. Found: C, 67.14; H, 6.60; N, 2.48; calc. for C60H72-
ClN2O5PPd (Mr = 1074.07): C, 67.09; H, 6.79; N, 2.61%.
2
4.52 and 3.40 [AB q, J = 14.6, 4H, ArCH2Ar], 4.52 and 3.29
2
[AB q, J = 14.9 Hz, 4H, ArCH2Ar], 1.99 (s, 3H, CH3-acac),
1.36 (s, 3H, CH3-acac), 1.33 [s, 18H, C(CH3)3], 1.17 [s, 9H,
C(CH3)3], 0.70 [s, 9H, C(CH3)3]. 13C{1H} NMR (75 MHz,
CDCl3): δ 187.23 and 187.00 (s × 2, CO), 146.29–124.13 (aryl
C), 101.65 (s, CH-acac), 73.21 [d, J(PC) = 56 Hz, P(O)CH2],
35.83 and 35.34 (s × 2, ArCH2Ar), 34.08 [s × 2, C(CH3)3], 33.63
Chloro(o-dimethylaminomethylphenyl-C,N){5,11,17,23-tetra-
tert-butyl-25-(diphenylphosphinoylmethoxy)-26,27,28-(ꢀ3-phos-
phorustrioxy)calix[4]arene}palladium(II) (14). L1 (0.107 g,
0.12 mmol) was added to a solution of [Pd(o-C6H4CH2-
NMe2)Cl]2 (0.031 g, 0.06 mmol) in CH2Cl2 (10 cm3). After
stirring for 1 h, the solvent was removed under vacuum. Re-
crystallisation from CH2Cl2–hexane at Ϫ78 ЊC gave 14 as a pale
yellow solid. Yield: 0.072 g, 0.062 mmol, 52%. Mp > 186 ЊC
[s × 2, C(CH3
) ], 33.11 (s × 2, ArCH Ar), 31.42 [s × 3,
3
2
C(CH3)3], 31.33 [s, C(CH3)3], 26.94 (CH3-acac), 25.46 (CH3-
acac). 31P{1H} NMR (121 MHz, CDCl3): δ 104.0 [d, J(PRh) =
300 Hz, P(OAr)3], 28.0 [s, P(O)Ph2]. Found: C, 67.66; H, 6.53;
calc. for C63H71O8P2Rh (Mr = 1121.09): C, 67.49; H, 6.38%.
Acetylacetonatocarbonyl{5,11,17,23-tetra-tert-butyl-25-
(ethoxycarbonylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)calix-
[4]arene}rhodium(I) (17). L2 (0.111 g, 0.15 mmol) was added
to a solution of [Rh(acac)(CO)2] (0.040 g, 0.15 mmol) in
CH2Cl2 (30 cm3). After stirring for 12 h, the volatiles were
evaporated under vacuum to give 17 as a yellow powder. Yield:
(decomp). IR (KBr) νmax/cmϪ1: 1185 (P᎐O, tentative assign-
᎐
ment). 1H NMR (200 MHz, CDCl3): δ 7.64–7.38, 7.28–7.19 and
7.06–6.62 (20 H, arom. H), 6.41 (s, 2H, m-ArH of calix), 5.17 (s,
2H, P(O)CH2), 4.77–4.70 (m, 4H, ArCH2Ar), 3.93 (s, 2H,
2
2
NCH2), 3.44 (d, J = 14, 2H, ArCH2Ar), 3.01 (d, J = 14, 2H,
4
0.135 g, 0.136 mmol, 90%. Mp 109–111 ЊC. IR (CH2Cl2) νmax
/
ArCH2Ar), 2.76 [d, J(PH) = 4.2 Hz, 6H, N(CH3)2], 1.31 [s,
1
cmϪ1: 2001s (CO), 1755m (C᎐O ester). H NMR (200 MHz,
18H, C(CH3)3], 1.19 [s, 9H, C(CH3)3], 0.86 [s, 9H, C(CH3)3].
᎐
2
13C{1H} NMR (50 MHz, CDCl3): δ 153.90–122.60 (aryl C),
CDCl3): δ 7.18 and 7.07 (AB q, J = 2.4, 4H, m-ArH), 7.05
3
(s, 2H, m-ArH), 6.59 (s, 2H, m-ArH), 5.36 (s, 1H, CH-acac),
72.90 [d, J(PC) = 4.9 Hz, NCH2], 72.65 [d, J(PC) = 80.8 Hz,
2
4.98 and 3.57 (AB q, J = 14.6, 4H, ArCH2Ar), 4.64 (s, 2H,
P(O)CH2], 50.38 [s × 2, N(CH3)2], 36.16 (s × 2, ArCH2Ar),
34.32 [s, C(CH3)3], 33.93 [s, C(CH3)3], 33.67 (s × 2, ArCH2Ar),
31.34 [s × 3, C(CH3)3], 31.01 [s, C(CH3)3]. 31P{1H} NMR (121
MHz, CDCl3): δ 82.3 [s, P(OAr)3], 26.5 [s, P(O)Ph2]. Found:
C, 68.10; H, 6.86; N, 1.24; calc. for C66H76ClNO5P2Pd (Mr =
1167.13): C, 67.92; H, 6.56; N, 1.20%.
OCH2CO2), 4.58 and 3.43 (AB q, 2J = 14.6, 4H, ArCH2Ar), 4.19
3
(q, J = 7.1, OCH2CH3), 2.03 (s, 3H, CH3-acac), 1.45 (s, 3H,
‡ L1 needs to be free of NEt3HCl. The presence of the latter leads to
formation of complex 19.
4272
J. Chem. Soc., Dalton Trans., 2002, 4264–4274

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3
CH3-acac), 1.35 [s, 18H, C(CH3)3], 1.28 (t, J = 7.1 Hz, OCH2-
164 ЊC (decomp). IR (KBr) νmax/cmϪ1: 1197.5 (P᎐O, tentative
᎐
1
CH3), 1.18 [s, 9H, C(CH3)3], 0.79 [s, 9H, C(CH3)3]. 13C{1H}
NMR (75 MHz, CDCl3): δ 186.91 and 185.70 (s × 2, CO),
170.00 (s, CO2), 153.61–124.20 (aryl C), 100.85 (s, CH-acac),
71.52 (s, OCH2CO2), 60.80 (s, OCH2CH3), 36.31 and 36.00 (s ×
2, ArCH2Ar), 34.42 [s × 2, C(CH3)3], 34.09 [s × 2, C(CH3)3],
33.77 (s × 2, ArCH2Ar), 31.47 [s × 3, C(CH3)3], 31.04
[s, C(CH3)3], 26.94 (CH3-acac), 25.58 (CH3-acac), 14.25 (s,
OCH2CH3). 31P{1H} NMR (121 MHz, CDCl3): δ 103.1 [d,
J(PRh) = 309 Hz, P(OAr)3]. Found: C, 65.48; H, 6.85; calc. for
C54H66O9PRh (Mr = 992.98): C, 65.32; H, 6.70%.
assignment). H NMR (200 MHz, CDCl3): δ 9.60–9.54 (1H,
arom. H of 8-mq), 8.31–8.26 (1H, arom. H of 8-mq), 7.65–7.43
and 7.13–6.99 [20 H, P(O)Ph2, arom. H of 8-mq and m-ArH],
2
6.51 (s, 2H, m-ArH), 4.95 [d, J = 1.7 Hz, 2H, P(O)CH2], 4.82
and 3.45 (AB q, 2J = 14, 2H each, ArCH2Ar), 4.65 and 3.41 (AB
q, 2J = 14.1 Hz, 2H each, ArCH2Ar), 1.36 [s × 2, 18H, C(CH3)3],
1.18 [s, 9H, C(CH3)3], 0.82 [s, 9H, C(CH3)3]. 13C{1H} NMR (50
MHz, CDCl3): δ 154.16–121.09 (aryl C), 72.82 [d, J(PC) = 80
Hz, P(O)CH2], 35.99 (s × 2, ArCH2Ar), 34.35 [s, C(CH3)3],
34.03 [s, C(CH3)3], 33.70 (s × 2, ArCH2Ar), 31.40 [s, C(CH3)3],
31.01 [s, C(CH3)3], 26.39 (s, CH2-8-mq). 31P{1H} NMR (121
MHz, CDCl3): δ 88.5 [s, P(OAr)3], 31.0 [br s, P(O)Ph2]. Found:
C, 63.30; H, 5.96; calc. for C67H72ClNO5P2PdؒCH2Cl2 (Mr =
1283.09) C, 63.34; H, 5.76%.
Acetylacetonatocarbonyl{5,11,17,23-tetra-tert-butyl-25-(di-
ethylcarbamoylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)calix-
[4]arene}rhodium(I) (18). L3 (0.119 g, 0.15 mmol) was added
to a solution of [Rh(acac)(CO)2] (0.040 g, 0.15 mmol) in
CH2Cl2 (30 cm3). After stirring for 12 h, the volatiles were
evaporated under vacuum to afford 18 as a yellow powder.
Yield: 0.143 g, 0.14 mmol, 93%. Mp 90–92 ЊC. IR (CH2Cl2)
(8-Methylquinolinylmethyl-C,N){5,11,17,23-tetra-tert-butyl-
25-(ethoxycarbonylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)-
calix[4]arene}palladium(II) tetrafluoroborate (21). A solution of
AgBF4 (0.017 g, 0.09 mmol) in THF (1 cm3) was added to a
solution of 12 (0.093 g, 0.09 mmol) in CH2Cl2 (20 cm3). After
stirring for 5 min, the solution was filtered through Celite and
concentrated under vacuum. Addition of hexane afforded 21 as
a pale yellow powder. Yield: 0.080 g, 0.073 mmol, 81%. Mp >
νmax/cmϪ1: 2000s (CO), 1634 (C᎐O amide). 1H NMR (300 MHz,
CDCl3): δ 7.17 and 7.07 (AB q, J = 2.5, 4H, m-ArH), 7.05
(s, 2H, m-ArH), 6.57 (s, 2H, m-ArH), 5.36 (s, 1H, CH-acac),
4.83 and 3.43 (AB q, J = 14.3, 4H, ArCH2Ar), 4.60 (s, 2H,
᎐
2
2
2
OCH2), 4.58 and 3.55 (AB q, J = 14.6, 4H, ArCH2Ar), 3.77
3
3
(q, J = 7.1, 2H, NCH2CH3), 3.41 (q, J = 7.3 Hz, 2H, NCH2-
CH3), 2.02 (s, 3H, CH3-acac), 1.40 (s, 3H, CH3-acac), 1.35 [s,
18H, C(CH3)3], 1.24–1.16 [m, 15H, C(CH3)3 and NCH2CH3],
0.79 [s, 9H, C(CH3)3]. 13C{1H} NMR (75 MHz, CDCl3): δ
187.23 and 186.74 (s × 2, CO), 167.69 [s, C(O)N], 153.69–
124.12 (aryl C), 101.59 (s, CH-acac), 73.90 (s, OCH2CONEt2),
41.92 and 39.90 (s × 2, CH2CH3), 35.89 (s × 2, ArCH2Ar),
34.36 [s, C(CH3)3], 34.04 [s × 2, C(CH3)3], 33.73 [s, C(CH3)3],
33.57 (s × 2, ArCH2Ar), 31.40 [s × 3, C(CH3)3], 30.99 [s,
C(CH3)3], 26.92 and 25.43 (s × 2, CH3-acac), 14.26 and 12.88
(s × 2, CH2CH3). 31P{1H} NMR (121 MHz, CDCl3): δ 102.7
[d, J(PRh) = 306 Hz, P(OAr)3]. Found: C, 66.22; H, 7.15; N,
1.21; calc. for C56H71NO8PRh (Mr = 1020.04): C, 65.94; H, 7.02;
N, 1.37%.
196–197 ЊC (decomp.). IR (CH2Cl2) νmax/cmϪ1: 1685 (C᎐O). 1H
᎐
NMR (300 MHz, CDCl3): δ 8.95–8.93, (m, 1H, arom. H of
8-mq), 8.35 (d, 3J = 8.2 Hz, 1H, arom. H of 8-mq), 7.65 (d, 3J =
8.0 Hz, 1H, arom. H of 8-mq), 7.45–7.30 (m, 3H, arom. H of
4
8-mq), 7.21 and 7.19 (AB q, J = 0, 4H, m-ArH), 7.13 (s, 2H,
m-ArH), 6.77 (s, 2H, m-ArH), 4.70 (s, 2H, OCH2CO2), 4.61 and
3.61 (AB q, 2J = 14.5, 4H, ArCH2Ar), 4.56 and 3.61 (AB q, 2J =
3
14.5, 4H, ArCH2Ar), 4.44 (q, J = 6.8, 2H, CH2CH3), 3.51 (s,
3
2H, CH2 of 8-mq), 1.35 (t, J = 6.8 Hz, 3H, CH2CH3), 1.35 [s,
18H, C(CH3)3], 1.21 [s, 9H, C(CH3)3], 0.94 [s, 9H, C(CH3)3].
13C{1H} NMR (50 MHz, CDCl3): δ 150.36–122.89 (aryl C),
71.95 (s, OCH2CO2), 63.53 (s, CH2CH3), 36.02 (s × 2,
ArCH2Ar), 34.45 [s, C(CH3)3], 34.16 [s × 2, C(CH3)3], 33.96 [s,
C(CH3)3], 33.70 (s × 2, ArCH2Ar), 31.27 [s × 3, C(CH3)3], 30.98
[s, C(CH3)3], 14.90 (s, CH2CH3), the CH2 signal of 8-mq was
not detected. 31P{1H} NMR (121 MHz, CDCl3): δ 87.8 [s,
P(OAr)3]. FAB mass spectrum: m/z 1010.4 ([M Ϫ BF4]ϩ, 100%).
Found: C, 63.21; H, 6.43; N, 1.32; calc. for C58H67BF4NO6PPd
(Mr = 1098.354): C, 63.42; H, 6.15; N, 1.28%.
Chlorocarbonylbis{5,11,17,23-tetra-tert-butyl-25-(diphenyl-
phosphinoylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)calix[4]-
arene}rhodium(I) (19). L1 (0.200 g, 0.11 mmol) was added to
a solution of [RhCl(CO)2]2 (0.022 g, 0.056 mmol) in CH2Cl2
(30 cm3). After stirring for 1 h, hexane was added to precipitate
the product. Yield: 0.189 g, 0.097 mmol, 88%. Mp 235–237 ЊC.
IR (KBr) νmax/cmϪ1: 1989s (CO). 1H NMR (300 MHz, CDCl3):
δ 7.87–6.93 (m, 32H, PPh2 and m-ArH), 6.58 (s, 4H, m-ArH),
(8-Methylquinolinylmethyl-C,N){5,11,17,23-tetra-tert-butyl-
25-(diethylcarbamoylmethoxy)-26,27,28-(ꢀ3-phosphorustrioxy)-
calix[4]arene}palladium(II) tetrafluoroborate (22). A solution of
AgBF4 (0.017 g, 0.09 mmol) in THF (1 cm3) was added to a
solution of 13 (0.095 g, 0.09 mmol) in CH2Cl2 (20 cm3). After
stirring for 5 min, the solution was filtered through Celite and
concentrated under vacuum. Addition of hexane afforded 22 as
a pale yellow powder. Yield: 0.094 g, 0.08 mmol, 95%. Mp >
2
5.40 (br s, 4H, PCH2), 4.70 and 3.26 (AB q, J = 13.9, 8H,
ArCH2Ar), 4.45 and 3.23 (AB q, 2J = 14.1 Hz, 8H, ArCH2Ar),
1.27 [s, 36H, C(CH3)3], 1.21 [s, 18H, C(CH3)3], 0.91[s, 18H,
C(CH3)3]. 13C{1H} NMR (50 MHz, CDCl3): δ 152.72–124.46
(aryl C), 72.53 [d, J(PC) = 77 Hz, P(O)CH2], 36.12 (s × 2,
ArCH2Ar), 34.49 [s, C(CH3)3], 34.25 (s × 2, ArCH2Ar), 34.00
[s × 2, C(CH3)3], 33.85 [s, C(CH3)3], 31.37 [s × 3, C(CH3)3],
31.14 [s, C(CH3)3]. 31P{1H} NMR (121 MHz, CDCl3): δ 93.4 [d,
J(PRh) = 223 Hz, P(OAr)3], 26.9 [s, P(O)Ph2]. FAB mass
spectrum: m/z 1021.3 ([M Ϫ L1 – Cl]ϩ, 73%), 1884.8 ([M Ϫ CO
Ϫ Cl ϩ H]ϩ, 75%), 1919.7 ([M Ϫ Cl ϩ H]ϩ, 9%). Found: C,
71.05; H, 6.84; calc. for C115H129O11P4Rh (Mr = 1948.49): C,
70.89; H, 6.62%.
229 ЊC (decomp.). IR (CH2Cl2) νmax/cmϪ1: 1603 (C᎐O). 1H
᎐
NMR (300 MHz, CDCl3): δ 8.68–8.64, 8.34–8.31, 7.90–7.85,
7.65–7.61 and 7.44–7.36 (6H, arom. H of 8-mq), 7.19 and 7.15
(AB q, 4J = 2.4, 4H, m-ArH), 7.17 (s, 2H, m-ArH), 6.98 (s, 2H,
2
m-ArH), 4.93 [s, 2H, OCH2C(O)N, 4.62 and 3.62 (AB q, J =
13.9, 4H, ArCH2Ar), 4.49 and 3.55 (AB q, 2J = 13.5, 4H,
3
ArCH2Ar), 3.72 (q, J = 7.2 Hz, 2H, CH2CH3), 3.58 (m, 4H,
CH2CH3 and CH2 of 8-mq), 1.31 (t, 6H, CH2CH3), 1.31 [s, 18H,
C(CH3)3], 1.24 [s, 9H, C(CH3)3], 1.13 [s, 9H, C(CH3)3]. 13C{1H}
NMR (50 MHz, CDCl3): δ 171.04 (s, CO), 151.47–123.36 (aryl
C), 71.14 [s, OCH2C(O)N], 42.84 and 42.26 (s × 2, CH2CH3),
36.32 (s × 2, ArCH2Ar), 34.60 (s × 2, ArCH2Ar), 34.50 [s,
C(CH3)3], 34.22 [s, C(CH3)3], 34.15 [s × 2, C(CH3)3], 31.32 [s,
C(CH3)3], 31.24 [s × 3, C(CH3)3], 20.02 (s, CH2-8-mq), 13.87
and 13.14 (s × 2, CH2CH3). 31P{1H} NMR (121 MHz, CDCl3):
δ 87.0 [s, P(OAr)3]. Found: C, 63.82; H, 6.46; N, 2.47; calc. for
C60H72BF4N2O5PPd (Mr = 1124.424): C, 64.03; H, 6.45; N,
2.49%.
(8-Methylquinolinylmethyl-C,N){5,11,17,23-tetra-tert-butyl-
25-(diphenylphosphinoylmethoxy)-26,27,28-(ꢀ3-phosphorustri-
oxy)calix[4]arene}palladium(II) tetrafluoroborate (20). A solu-
tion of AgBF4 (0.016 g, 0.082 mmol) in THF (1 cm3) was added
to a solution of 11 (0.100 g, 0.085 mmol) in CH2Cl2 (20 cm3).
After stirring for 5 min, the solution was filtered through Celite
and evaporated to dryness. 20 Was obtained as a pale yellow
powder by recrystallisation from an ethyl acetate–hexane
mixture at Ϫ78 ЊC. Yield: 0.53 g, 0.043 mmol, 51%. Mp > 163–
J. Chem. Soc., Dalton Trans., 2002, 4264–4274
4273

View Article Online
Hydroformylation experiments
References
The hydroformylation experiments were carried out in a glass-
lined, 100 cm3 stainless steel autoclave containing a magnetic
stirring bar. In a typical run, the autoclave was charged under
nitrogen with 0.5 cm3 of a 4 mM toluene solution of [Rh-
(acac)(CO)2], 10 equiv. of ligand (0.02 mmol) and 14.5 cm3 of
toluene. Once closed, the autoclave was flushed twice with syn-
gas (CO–H2 1:1 v/v), then pressurised with 15 bar of the CO–H2
mixture and heated for 2 h at 80 ЊC. The autoclave was then
allowed to cool to room temperature and depressurised. A
mixture of internal standard (decane, 0.5 cm3, 2.56 mmol) and
1-octene (1.57 cm3, 10 mmol) was then added to the catalyst
mixture. The autoclave was pressurised to 20 bar, then heated to
80 ЊC (leading to a 22 bar pressure). Progress of the reaction
was checked by monitoring the pressure decrease. During the
experiments, several samples were taken, which were diluted
with toluene and analysed by GC. In view of the relatively low
isomerisation observed, the reaction was not quenched with
P(OBun)3 at the end of the catalytic run.
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X-Ray crystallography
Crystal data for 9. Crystals suitable for X-ray diffraction were
obtained by slow evaporation of an acetonitrile solution of
the complex: C114H128Cl2O10P4Ptؒ5CH3CNؒH2O, M = 2271.46,
¯
triclinic, space group P1, colourless, a = 16.3979(1), b =
17.5637(1), c = 24.1629(1) Å, α = 71.905(6), β = 84.340(6), γ =
65.213(6)Њ, U = 6001.5(1) Å3, Dc = 1.26, Z = 2, µ = 1.325 mmϪ1
,
F(000) = 2368. Data were collected on a Nonius KappaCCD
diffractometer (graphite Mo-Kα radiation, λ = 0.71073 Å) at
Ϫ100 ЊC. 37630 Reflections collected with (2.5 < θ < 27.53Њ),
22183 data with I > 3σ(I). The structure was solved by direct
methods and refined anisotropically on F 2 using the Open-
MoleN package.41 Hydrogen atoms were included using a
riding model or rigid methyl groups. No hydrogen atoms were
located by Fourier difference for either the acetonitrile or
the water molecules. Some atoms were refined isotropically
[C(108)–C(113), C(117), C(118), N(2), O(11)]. The molecule
crystallises with 5 acetonitrile molecules, two of which are
located inside the two calixarene cavities, and one water
molecule. Final results: R(F) = 0.060, wR(F) = 0.074, good-
ness of fit = 1.077, 1256 parameters, largest difference peak =
1.3 e ÅϪ3
.
Crystal data for 22. Crystals suitable for X-ray diffraction
were obtained by slow diffusion of hexane into a dichloro-
methane solution of the complex: C60H72BF4N2O5PPdؒ
27 R. Paciello, L. Siggel and M. Röper, Angew. Chem., Int. Ed., 1999,
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USA, 1998.
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Perkin Trans 2, 2000, 1315–1321.
¯
3CH2Cl2ؒ0.5C6H14, M = 1423.24, triclinic, space group P1, pale
yellow, a = 13.7230(4), b = 14.6378(4), c = 18.4221(6) Å, α =
87.411(2), β = 88.7070(13), γ = 78.6180(13)Њ, U = 3623.70(19)
Å3, Dc = 1.304, Z = 2, µ = 0.555 mmϪ1, F(000) = 1478. Data were
collected on a Nonius KappaCCD diffractometer (graphite
Mo-Kα radiation, λ = 0.71073 Å) at Ϫ90 ЊC. 21214 Reflections
collected with (1.02 < θ < 27.48Њ), 9432 data with I > 2σ(I). The
structure was solved by direct methods and refined anisotropic-
ally on F 2 using the SHELXL-97 procedure.42 Hydrogen atoms
were included using a riding model or rigid methyl groups.
The hexane molecule has been idealised. Final results: R(F 2) =
0.063, wR(F 2) = 0.176, goodness of fit = 1.048, 773 parameters,
largest difference peak = 1.56 e ÅϪ3
.
CCDC reference numbers 184801 and 184802.
See http://www.rsc.org/suppdata/dt/b2/b204604k/ for crystal-
lographic data in CIF or other electronic format.
38 P. Braunstein and F. Naud, Angew. Chem., Int. Ed., 2001, 40, 680.
39 A. van Rooy, E. N. Orij, P. C. J. Kamer and P. W. N. M. van
Leeuwen, Organometallics, 1995, 14, 34.
40 H. J. Clark, R. Wang and H. Alper, J. Org. Chem., 2002, 67, 6224.
41 OpenMoleN, Interactive Structure Solution, Nonius B.V., Delft,
The Netherlands, 1997.
42 G. M. Sheldrick, SHELX-97, Program for the Refinement of
Crystal Structures, University of Göttingen, Germany, 1997.
Acknowledgements
We are grateful to Johnson Mathey for a generous loan of
precious metals.
4274
J. Chem. Soc., Dalton Trans., 2002, 4264–4274