Synthesis and characterization of the inclusion compound of a methyltrioxorhenium(VII) adduct of 4-ferrocenylpyridine with β-cyclodextrin

Article abstract of DOI:10.1016/S0022-328X(02)01635-2

An organometallic Lewis base adduct of methyltrioxorhenium(VII) (MTO), comprising the ligand 4-ferrocenylpyridine, has been isolated and characterized. The binuclear complex and also the precursor free ligand have been immobilized in β-cyclodextrin (CD) t

Full text of DOI:10.1016/S0022-328X(02)01635-2

Journal of Organometallic Chemistry 656 (2002) 281ꢀ287
/
www.elsevier.com/locate/jorganchem
Synthesis and characterization of the inclusion compound of a
methyltrioxorhenium(VII) adduct of 4-ferrocenylpyridine with
b-cyclodextrin
Lu´ıs Cunha-Silva a, Isabel S. Goncalves a,*, Martyn Pillinger a, Wen-Mei Xue b,
¸
Joao Rocha a, Jose´ J.C. Teixeira-Dias a, Fritz E. Kuhn b
˜
¨
a Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
b Anorganisch-Chemisches Institut der Technischen Universitat Munchen, Lichtenbergstrasse 4, D-85747 Garching bei Munchen, Germany
¨
¨
¨
Received 22 April 2002; received in revised form 3 June 2002; accepted 7 June 2002
Abstract
An organometallic Lewis base adduct of methyltrioxorhenium(VII) (MTO), comprising the ligand 4-ferrocenylpyridine, has been
isolated and characterized. The binuclear complex and also the precursor free ligand have been immobilized in b-cyclodextrin (CD)
to give inclusion complexes with a one-to-one stoichiometry. Powder X-ray diffraction (XRD) indicates that the microcrystalline
powders obtained are true homogeneous inclusion complexes. This is corroborated by thermogravimetric analysis (TGA), which
indicates that the ferrocenylpyridine ligand gains an additional thermal stability upon encapsulation. FTIR and 13C- solid-state CP
MAS NMR spectroscopy confirm that the ReꢀN ligation is intact for the included binuclear complex. The NMR results also
/
support the conclusion that the monosubstituted ferrocene derivatives adhere to an inclusion model in which the ferrocene
penetrates deeply into the CD cavity in axial mode while the substituent protrudes out. # 2002 Elsevier Science B.V. All rights
reserved.
Keywords: Cyclodextrins; Inclusion compounds; Lewis base adducts; Methyltrioxorhenium; Ferrocene derivatives
1. Introduction
nonlinear optical properties [7,8], and ligand substitu-
tion/insertion reactions [9,10]. CD are known to bind
Cyclodextrins (CDs) are cyclic oligosaccharides con-
ferrocene and its derivatives [11ꢀ17], titanocene and
/
sisting of six, seven or eight (10
anose units (a-, b- and g-CD, respectively) [1ꢀ
form inclusion complexes with smaller molecules that fit
/
4)-linked a-
D
-glucopyr-
molybdenocene dihalides [18,19], aromatic ruthenium
complexes [20], mixed sandwich complexes such as [(h5-
C5H5)Fe(h6-C6H6)](PF6) [21], and half-sandwich com-
/3]. They
˚
into their 5ꢀ
/
8 A cavity [3ꢀ5]. Suitable guests include
/
plexes such as CpFe(CO)2X (XꢁCl, Me) [9,10,22],
/
[CpFe(CO)2NH3](PF6) [23], CpMn(CO)3 [24], (h6-
C6H6)Cr(CO)3 [25], Cp?Mo(h3-C3H5)(CO)2 [26],
Cp?Mo(h3-C6H7)(CO)2 and [Cp?Mo(h4-C6H8)(CO)2]-
transition metal complexes and organometallic com-
pounds bearing hydrophobic ligands such as cyclopen-
tadienyl (Cpꢁ
h5-C5H5) and h6-arene groups [5,6].
/
With these ligands, the weaker categories of non-
covalent bonding, e.g. van der Waals and charge
transfer interactions, assume considerable importance.
Encapsulated metallo-organic complexes often exhibit
markedly different physical and chemical properties
compared with the bulk material, for example, in their
(BF4) (Cp?ꢁ
(host-to-guest) adduct with a-CD, and 1:1 adducts with
b and g-CD [11ꢀ14]. On the other hand, the interaction
/Cp, Ind) [27]. Ferrocene itself forms a 2:1
/
of CD with binuclear organometallic compounds has
scarcely been studied [28]. In the present work, 4-
ferrocenylpyridine and its 1:1 adduct with methyltriox-
orhenium(VII) (MTO) have been immobilized in b-CD
and the resulting novel inclusion compounds character-
ized by a range of solid-state physicochemical techni-
ques.
* Corresponding author. Tel.: ꢂ
370084
E-mail address: igoncalves@dq.ua.pt (I.S. Goncalves).
/
351-234-370200; fax: ꢂ351-234-
/
¸
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 3 5 - 2

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/
2. Results and discussion
because they are far apart from the ReVII. The proton
NMR signal corresponding to the methyl group of 2
appears at d 1.88 which is shifted notably upfield
compared with the un-coordinated MTO (d 2.67) as a
result of the electron density donated by the N-donor
ligand to the Lewis acidic ReVII. The 1:1 adduct of
pyridine with MTO gave a similar chemical shift for this
resonance (d 1.90) [32].
2.1. Synthesis and characterization of guest species
Lewis base adducts of MTO, particularly pyridine
derivatives, are interesting to study because the addition
of Lewis bases to MTO-catalyzed olefin epoxidations
significantly reduces the formation of diols [29]. Re-
cently, it was shown that MTO forms trigonal-bipyr-
amidal adducts with 1,1?-bis(4-pyridylethynyl)ferrocene
and ferrocenyl-4-pyridylacetylene [30]. These were the
first stable and fully characterized organometallic Lewis
base adducts of MTO to be reported. We have now
prepared another organometallic Lewis base adduct of
MTO, containing the ligand 4-ferrocenylpyridine (1).
The ligand 1 was prepared by nickel-catalyzed coupling
of the Grignard reagent from bromoferrocene with 4-
bromopyridine [31]. Treatment of MTO with one
equivalent of 1 in diethyl ether at room temperature
immediately leads to the formation of complex 2
(Scheme 1), which can be isolated from the orange
suspension as a light orange solid in good yield. The
pyridyl ring stretching vibration of 2 appears at 1606
cmꢃ1, the corresponding band of 1 at 1598 cmꢃ1. A
similar shift in the frequency of this vibration was
observed upon coordination of ferrocenyl-4-pyridylace-
2.2. Synthesis and characterization of b-CD inclusion
compounds
Mixing of an aqueous solution of b-CD with a
solution of 1 or 2 in dichloromethane results in the
formation of an orange precipitate at the interface
between the two solutions. The products 3 and 4 were
isolated by filtration, rinsed with water and dichloro-
methane, and dried in vacuo at ambient temperature
(Scheme 1). Elemental analysis supports the formation
of stoichiometric 1:1 (host-to-guest) inclusion com-
pounds. The washing steps did not liberate the guests
from the host cavities. The products were further
characterized in the solid-state by thermogravimetric
analysis (TGA), powder X-ray diffraction (XRD),
FTIR and 13C- CP MAS NMR spectroscopy.
2.2.1. Powder XRD and TGA
tylene to MTO [30]. The Reꢀ
/
O stretching vibrations are
The b-CD adducts 3 and 4 were obtained as micro-
crystalline powders and examined by powder XRD (Fig.
1). Also shown are the diffraction patterns of plain b-
CD hydrate, 4-ferrocenylpyridine (1) and (4-ferrocenyl-
pyridine)methyltrioxorhenium (2). Clearly, 3 and 4 do
not contain measurable amounts of non-included crys-
talline 1 and 2, respectively. The patterns for 3 and 4 are
quite different from that of b-CD hydrate, suggesting
that true inclusion complexes exist in the solid state [4].
Powder XRD can sometimes be used to quickly identify
the type of crystal packing that exists in cyclodextrin
inclusion compounds. For example, it was possible to
show that channel-type inclusion compounds are
formed after reacting b-CD with the half-sandwich
molybdenum complexes CpMo(h3-C3H5)(CO)2, In-
dMo(h3-C3H5)(CO)2 [26], CpMo(h3-C6H7)(CO)2 and
shifted from 958 (asym.) and 1005 cmꢃ1 (sym.) for
MTO to 930 and 942 cmꢃ1 for 2, reflecting the donor
capacity of ligand 1. The 17O-NMR shift for 2 (d 865) is
significantly down-field shifted compared with free
MTO (d 829), indicating that less electron density is
withdrawn from the terminal oxygen ligands. The
pyridyl protons of 2 [d(Ha) 8.11, d(Hb) 7.40] differ in
their chemical shift from those of 1 [d(Ha) 8.44, d(Hb)
7.30]. On the other hand, the ferrocene proton reso-
nances are comparable with those of the ‘free’ ligand,
[CpMo(h4-C6H8)(CO)2](BF4) (Cpꢁ
/
h5-C5H5, Indꢁ
/
C9H7) [27]. However, in the cases of 3 and 4, no clear
conclusions can be drawn from the powder XRD data
about the type of crystal packing.
Thermal analysis methods can be used for the
recognition of inclusion complexation [33]. Fig. 2 shows
the results of TGA of 4-ferrocenylpyridine (1), 4-
ferrocenylpyridine×b-CD (3), plain b-CD hydrate and
/
a physical mixture of b-CD and 1 in a 1:1 molar ratio.
TGA of b-CD shows loss of hydrated water up to
130 8C (14.4%, 10ꢀ11 water molecules per b-CD
/
molecule), the maximum rate of mass loss occurring at
90 8C. There is no further change until 260 8C when
Scheme 1.

L. Cunha-Silva et al. / Journal of Organometallic Chemistry 656 (2002) 281ꢀ
/287
283
Fig. 1. Powder XRD patterns of (a) plain b-CD hydrate, (b) 4-ferrocenylpyridine (1), (c) 4-ferrocenylpyridine b-CD (3), (d) (4-ferrocenylpyr-
idine)methyltrioxorhenium (2), and (e) (4-ferrocenylpyridine)methyltrioxorhenium×b-CD (4).
/
the compound starts to melt and decompose, character-
ized by an intense, sharp peak in the differential
thermogravimetric (DTG) profile at 287 8C. At
500 8C, 100% mass loss is complete. The organometallic
Lewis base ligand 1 starts to melt at 135 8C and then
decomposes in a single stage, losing 83.5% mass up to
dehydration of b-CD takes place, the organometallic
ligand melts and decomposes, and b-CD melts and
decomposes. The inclusion compound 3 is stable under
N2 up to 250 8C except for loss of water in the
temperature range 25ꢀ175 8C (10%, nine to ten water
/
molecules per b-CD molecule). Unlike the physical
mixture, no clear step is observed corresponding to
decomposition of the ‘free’ ligand 1. Instead, the
liberation of the organometallic ligand and degradation
of the b-CD structure occur in the same temperature
240 8C (DTGmax
ꢁ230 8C). At 360 8C the residual
/
mass is 7%. In the case of the physical mixture each
component behaves independently. Steps are visible in
the TG profile corresponding to the stages where

284
L. Cunha-Silva et al. / Journal of Organometallic Chemistry 656 (2002) 281ꢀ287
/
rupture of the Reꢁ/N bond and sublimation of the now
un-coordinated MTO. Pure MTO sublimes below
100 8C under TG conditions [34]. Coordination of
MTO to 1 obviously improves its thermal stability to a
certain degree. In the case of the physical mixture of b-
CD and 2, two steps are observed below 150 8C
corresponding to loss of hydrated water from b-CD
and the first stage in the decomposition of ‘free’ 2. As
observed for b-CD and 1, decomposition of the physical
mixture can be interpreted in terms of decomposition of
the individual components. The inclusion compound 4
displays a TG profile similar to that observed for 3. A
mass loss of 13% is recorded in the temperature range
25ꢀ210 8C. There is a shallow step centred at about
/
133 8C, presumably due to fragmentation of the
included complex and subsequent sublimation of
MTO. Further heating reveals a very different decom-
position behavior than that observed for the physical
mixture. An abrupt mass loss of 62% occurs in the
Fig. 2. TGA of 4-ferrocenylpyridine×
/
b-CD (3) (*
/
), 4-ferrocenylpyr-
temperature range 210ꢀ
/
250 8C (DTGmax
ꢁ240 8C).
/
idine (1) (ꢀ ), free b-CD hydrate (*
/
ꢀ
/
ꢀ
/
ꢀ
/
/
-*-), and a physical
/
Further heating gives a residual mass of 6.0% at 800 8C.
mixture of b-CD and 1 in a 1:1 molar ratio (Á Á ÁÁ Á ÁÁ Á Á).
2.2.2. FTIR and solid-state 13C- CP MAS NMR
spectroscopy
range and are impossible to distinguish. A very rapid
mass loss of 84% occurs in the temperature range 250ꢀ
/
The KBr IR spectra of the inclusion compounds 3 and
4 show several new absorption bands on top of the
characteristic vibrations of the host. These are assigned
to vibrations of the guest molecules. In the case of 3, the
280 8C (DTGmax 267 8C). These results indicate that
ꢁ
/
the ferrocene derivative gains an additional thermal
stability after inclusion complexation into the b-CD
cavity.
Three main stages are observed in the thermal
decomposition of the adduct (4-ferrocenylpyridi-
ne)methyltrioxorhenium (2) (Fig. 3), characterized by
DTG maximums at 135, 375 and 500 8C. The first
stage, which begins at 105 8C, must correspond to
pyridyl ring stretching vibration appears at 1604 cmꢃ1
,
compared with 1598 cmꢃ1 for the ‘free’ ligand 1. This
shift difference may be due to a number of factors,
including the effect of placing the pyridyl ring in the
constrained environment of the host. There may also be
a hydrogen-bonding interaction with the hydroxyl
groups of the host. Both 3 and 4 display at least one
band in the range 800ꢀ
/
850 cmꢃ1 that can be assigned to
out-of-plane CꢁH deformations of the cyclopentadienyl
/
and/or pyridyl rings of the guest molecules. The pyridyl
ring stretching vibration of 4 appears in the same
position as that for the non-included adduct 2 (1606
cmꢃ1), which is an initial indication that the structural
integrity of the binuclear complex is retained in the
encapsulated state. This is confirmed by the presence of
medium intensity bands for the Reꢀ
/
O stretching vibra-
tions at 930 and 941 cmꢃ1, un-shifted compared with 2.
The solid-state 13C- CP MAS NMR spectra of b-CD
hydrate, 4-ferrocenylpyridine (1) and 4-ferro-
cenylpyridine×b-CD (3) are shown in Fig. 4. The
/
spectrum of b-CD hydrate is similar to that previously
reported and exhibits multiple resonances for each type
of carbon atom [35ꢀ
with different torsion angles about the (10
/
37]. This has been mainly correlated
4) linkages
/
for C-1 and C-4 [35,36], and with torsion angles
describing the orientation of the hydroxyl groups [37].
The different carbon resonances are assigned to C-1
Fig. 3. TGA of (4-ferrocenylpyridine)methyltrioxorhenium×
(*), (4-ferrocenylpyridine)methyltrioxorhenium (2) (ꢀ
CD hydrate (*-*-), and a physical mixture of b-CD and 2 in a 1:1
molar ratio (Á Á ÁÁ Á ÁÁ Á Á).
/
b-CD (4)
), free b-
/
/
ꢀ/
ꢀ/
ꢀ
/
/
/
(101ꢀ
/
104 ppm), C-4 (78ꢀ
/
84 ppm), C-2,3,5 (71ꢀ76 ppm)
/

L. Cunha-Silva et al. / Journal of Organometallic Chemistry 656 (2002) 281ꢀ
/287
285
Fig. 4. Solid-state 13C- CP MAS NMR spectra of (a) plain b-CD
hydrate, (b) 4-ferrocenylpyridine (1), and (c) 4-ferrocenylpyridine×b-
CD (3). Asterisks denote spinning sidebands.
Fig. 5. Solid-state 13C- CP MAS NMR spectra of (a) plain b-CD
hydrate, (b) (4-ferrocenylpyridine)methyltrioxorhenium (2), and (c) (4-
/
ferrocenylpyridine)methyltrioxorhenium×b-CD (4). Asterisks denote
/
spinning sidebands.
and C-6 (57ꢀ65 ppm). Contrastingly, the b-CD carbons
/
C-1, C-2,3,5 and C-6 for complex 3 are observed as
single broad peaks at 103.3, 73.2 and 60.1 ppm,
respectively. This is a clear indication that the ferrocenyl
derivative is included in the cavities of b-CD, as it
implies that b-CD adopts a more symmetrical confor-
mation in the complex, with each glucose unit in a
similar environment [38]. Additional peaks in the
spectrum are readily assigned to the resonances of the
carbon atoms of the guest molecule. The cyclopentadie-
nyl and pyridyl rings give rise to peaks at 65.7 (C5H4),
70.2 (C5H5), 120.3 (C5H4N) and 148.5 ppm (C5H4N),
largely un-shifted compared with the corresponding
resonances for pure 1. Comparable results were ob-
tained for the inclusion complex 4 containing the
binuclear adduct 2 (Fig. 5). The resonances for the Cp
and methyl carbons of the guest molecule are observed
at 70.8 and 30.0 ppm, respectively. These are un-shifted
compared with the corresponding resonances for ‘free’
2.
3. Concluding remarks
An organometallic Lewis base adduct of MTO has
been prepared and successfully immobilized in b-CD to
give a true inclusion complex in a crystalline state.
Spectroscopic evidence confirms that MTO remains
coordinated to the organometallic ligand in the encap-
sulated guest species. The poor solubility of the inclu-
sion complex in most solvents precludes its use in
homogeneous catalysis, or liquid-phase biphasic cataly-
sis. Use of a modified CD may improve this situation
and is the focus of current research in our laboratories.
4. Experimental
4.1. General remarks
All air-sensitive operations were carried out under an
atmosphere of nitrogen or argon using standard Schlenk
techniques. Solvents were dried by standard procedures,
˚
distilled under nitrogen or argon, and stored over 4 A
molecular sieves. Microanalyses were performed at the
ITQB (Oeiras, Portugal) and the Mikroanalytisches
The inclusion complex 4 was not effective as a catalyst
for the heterogeneous epoxidation of cyclooctene by
hydrogen peroxide (see Section 4 for details). After 24 h
reacting, the conversion was 8.8% with selectivity to the
epoxide of 27%.

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/
Labor of the TU Munchen in Garching. TGA studies
¨
6.46; N, 0.77; Fe, 3.32. (C15H13NFe)×
10H2O (1578.25) requires C, 43.38; H, 6.56; N, 0.89;
Fe, 3.54%*
nmax (cmꢃ1) 3381vs, 2925s, 1604m, 1413m,
/
(C42H70O35)×
/
were performed using a Shimadzu TGA-50 system at a
heating rate of 5 K minꢃ1 under a nitrogen atmosphere.
Powder XRD data were collected on a Philips X’pert
/
1385m, 1368m, 1335m, 1302m, 1245m, 1202m, 1157vs,
1104s, 1080vs, 1055s, 1030vs, 1004m, 947m, 939m,
diffractometer using Cuꢀ
/
Ka radiation filtered by Ni
(lꢁ
/
1.5418 A). Infrared spectra were recorded on a
859m, 823m, 756m, 706s, 608m, 579s, 531s (KBr)*13
C-
/
˚
Unican Mattson Mod 7000 FTIR spectrophotometer
using KBr pellets. 1H- and 13C-NMR spectra were
recorded on a Bruker 270 spectrometer, and 17O-
NMR spectra on a Bruker Avance DPX-400 spectro-
meter. 13C- solid-state CP MAS NMR spectra were
recorded at 125.72 MHz on a (11.7 T) Bruker Avance
500 spectrometer, with a 4.5 ms 1H 908 pulse, 2 ms
contact time, a spinning rate of 9 kHz and 12 s recycle
delays. Chemical shifts are quoted in parts per million
from tetramethylsilane (TMS).
b-CD was obtained from Wacker Chemie and recrys-
tallized before use. 4-Ferrocenylpyridine (1) was pre-
pared as described in the literature [31]. 13C- CP MAS
NMR of 1: d 149.7, 147.6 (Ca of C5H4N), 121.7, 118.8
(Cb of C5H4N), 80.8 (C5H4), 70.7 (C5H5), 68.3 (C5H4).
CP MAS NMR (see Fig. 6 for labeling): d 148.5 (s,
C5H4N), 120.3 (s, C5H4N), 103.3 (b-CD, C-1), 81.9, 80.7
(b-CD, C-4), 73.2 (b-CD, C-2,3,5), 70.2 (sh, C5H5), 65.7
(C5H4), 60.1 (b-CD, C-6).
4.4. (4-Ferrocenylpyridine)methyltrioxorhenium×
/b-CD
(4)
A solution of b-CD (0.44 g, 0.39 mmol) in water (18
ml) was treated with a solution of 2 (0.20 g, 0.39 mmol)
in dichloromethane (6 ml) and the mixture kept at r.t.
for 48 h. The suspension was filtered and the pale orange
powder washed several times with water (15 ml),
dichloromethane (5 ml), and vacuum dried. Yield: 0.38
g (55%). Found: C, 39.08; H, 6.00; N, 0.68; Fe, 2.98.
(C16H16NO3FeRe)×
/
(C42H70O35)×
/
8H2O (1791.46) re-
4.2. (4-Ferrocenylpyridine)methyltrioxorhenium (2)
quires C, 38.88; H, 5.74; N, 0.78; Fe, 3.11%*
/nmax
(cmꢃ1) 3374vs, 2926s, 1631m, 1607m, 1520m, 1433m,
1412m, 1384m, 1368m, 1334m, 1300m, 1225m, 1208m,
1157vs, 1106s, 1080vs, 1056s, 1030vs, 1006m, 941m,
930s, 892m, 862m, 840m, 821m, 758m, 705m, 688m,
668m, 609m, 579s, 529m, 497m, 479m, 412m
A solution of CH3ReO3 (0.30 g, 1.2 mmol) in diethyl
ether (15 ml) was treated with 4-ferrocenylpyridine (0.32
g, 1.2 mmol). The color of the solution changed to
orange and immediately a solid started to precipitate.
After 60 min, the solution was evaporated to dryness
and the product washed with n-hexane (20 ml). Yield:
0.59 g (96%). Found: C, 37.52; H, 2.82; N, 2.60; Fe,
10.84. C16H16NO3FeRe (512.35) requires C, 37.51; H,
(KBr)*13
C- CP MAS NMR: d 146.2 (s, C5H4N),
/
120.7 (s, C5H4N), 103.7 (b-CD, C-1), 80.6 (b-CD, C-
4), 72.7 (b-CD, C-2,3,5), 70.8 (sh, C5H5), 65.7 (C5H4),
60.4 (b-CD, C-6), 30.0 (CH3ReO3).
3.15; N, 2.73; Fe, 10.90%*
nmax (cmꢃ1) 3101m, 1606vs,
/
1522m, 1433m, 1388m, 1383m, 1294m, 1225m, 1209m,
1107m, 1066m, 1040m, 1020s, 1011s, 942vs, 930vs,
892m, 862m, 839m, 830m, 820m, 688m, 644m, 562m,
4.5. Catalytic epoxidation of cyclooctene
cis-Cyclooctene (400 mg, 3.65 mmol) and n-dibuty-
lether (400 mg, internal standard), 1 mol% (36 mmol) 4
(as catalyst), appropriate amount of ligand and 2.5 ml of
529m, 517m, 496m, 479m, 436m (KBr)*dH (270 MHz,
/
CD2Cl2, room temperature (r.t.)) 8.11 (d, 2 H, Ha of
C5H4N), 7.40 (d, 2 H, Hb of C5H4N), 4.77 (t, 2 H, Ha of
C5H4), 4.51 (t, 2 H, Hb of C5H4), 4.04 (s, 5 H, C5H5),
1.88 (s, 3 H, CH3ReO3). dC (CD2Cl2, r.t.) 153.25
(C5H4N), 147.05 (C5H4N), 121.97 (C5H4N), 79.41
(C5H4), 71.63 (C5H4), 70.62 (C5H5), 67.73 (C5H4),
CH2Cl2ꢀCHCl3 were added to a thermostated reaction
/
vessel. Hydrogen peroxide (0.8 ml, 35%, 9.3 mmol) was
added to start the reaction. The two phase reaction
system was stirred for 24 h. The course of the reaction
was monitored by quantitative GC analysis; samples
were taken from the organic phase, diluted with CH2Cl2,
and treated with a catalytic amount of MnO2 and
MgSO4 to destroy the hydrogen peroxide and remove
water. The resulting slurry was filtered over a filter
equipped with a Pasteur pipette, and the filtrate injected
24.88 (CH3ReO3)*13
C- CP MAS NMR: d 153.1,
/
146.1, 143.5, 123.2, 122.5, 79.6, 70.7, 68.9, 29.9. dO
(54.14 MHz, CD2Cl2, r.t.) 865.4.
4.3. 4-Ferrocenylpyridine×
/
b-CD (3)
A solution of b-CD (0.21 g, 0.18 mmol) in water (6
ml) was treated with a solution of 4-ferrocenylpyridine
(0.05 g, 0.18 mmol) in dichloromethane (1.5 ml) and the
mixture kept at 40 8C for 17 h. The suspension was
filtered and the pale orange powder washed several
times with water (10 ml), dichloromethane (3 ml), and
vacuum dried. Yield: 0.19 g (68%). Found: C, 42.99; H,
Fig. 6.

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287
[15] A.E. Kaifer, Acc. Chem. Res. 32 (1999) 62.
[16] D. Osella, A. Carretta, C. Nervi, M. Ravera, R. Gobetto,
into a GC column. The conversion of cis-cyclooctene
and the yield of cyclooctene epoxide were calculated
Organometallics 19 (2000) 2791.
[17] P. Ferreira, I.S. Goncalves, M. Pillinger, J. Rocha, P. Santos,
from a calibration curve (r2ꢁ
0.999) recorded prior to
the reaction course.
/
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We are grateful to the FCT for partial funding
(project POCTI/QUI/37990/2001). I.S.G. and W.M.X.
acknowledge the Bayerische Forschungsstiftung for
research grants. F.E.K. is grateful to the FCI for
financial support. We also wish to thank Marta Lopes
and Claudia Morais for assistance in the NMR experi-
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