Communications
our knowledge, the 1·2 supramolecular entity is the first
water-soluble self-assembled P,N mixed donor described. Its
chelating properties have been demonstrated on platinum
and lead to three different coordination complexes. On the
basis of these encouraging results, we are currently compiling
a library of heterobidentate ligands to evaluate their perform-
ances in biphasic organometallic catalysis.
Received: December 21, 2006
Published online: March 16, 2007
3
1
Figure 4. P NMR spectrum (recorded at room temperature in D O)
2
Keywords: cyclodextrins ·hydrogenation ·N,P ligands ·
platinum ·self-assembly
of the brown precipitate resulting from the addition of methanol to the
initial mixture of 3, 4,and 5.
.
The broad signal at d = 14 ppm (line width > 200 Hz) in
Figure 1 (violet peak) was attributed to 5 by comparison with
[
1] E. Monflier, F. Hapiot, D. OꢀHare in Comprehensive Organo-
metallic Chemistry III, Vol. 12 (Eds.: R. H. Crabtree, D. M. P.
Mingos) Elsevier, Oxford, 2006, pp. 781 – 834.
[
9]
1
previous data (see Supporting Information). The JP, P t
coupling constant of 3755 Hzwas characteristic of two
phosphanes oriented cis to each other. One of the platinum-
coordinated phosphanes was included in 1, which conse-
[2] a) M. J. Wilkinson, P. W. N. M. van Leeuwen, J. N. H. Reek, Org.
Biomol. Chem. 2005, 3, 2371 – 2383; b) A. J. Sandee, J. N. H.
Reek, Dalton Trans. 2006, 3385 – 3391.
[3] P. W. N. M. van Leeuwen, P. C. J. Kamer, J. N. H. Reek, P.
Dierkes, Chem. Rev. 2000, 100, 2741 – 2770.
[
13]
quently acted as a second-sphere ligand. The broadening of
the peak at d = 14 ppm is a consequence of the dynamic
[
4] a) B. Breit, W. Seiche, Pure Appl. Chem. 2006, 78, 249 – 256;
b) M. Kuil, T. Soltner, P. W. N. M. van Leeuwen, J. N. H. Reek, J.
Am. Chem. Soc. 2006, 128, 11344 – 11345; c) M. Kuil, P. E.
Goudriaan, P. W. N. M. van Leeuwen, J. N. H. Reek, Chem.
Commun. 2006, 4679 – 4681; d) J. M. Takacs, K. Chaiseeda,
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Jiang, L. Lefort, P. E. Goudriaan, A. H. M. de Vries, P. W. N. M.
van Leeuwen, J. G. de Vries, J. N. H. Reek, Angew. Chem. 2006,
[
14]
inclusion of 2 in the cavity of 1
and also arises from
À
[16]
chemical exchange of Cl for H O.
2
Experiments were performed to evaluate the efficiency of
the above-described coordination complexes as catalysts in
the hydrogenation reaction of 2-methyl-3-buten-2-ol
(
Scheme 3). This substrate was chosen to avoid mass-transfer
118, 1245 – 1249; Angew. Chem. Int. Ed. 2006, 45, 1223 – 1227;
f) M. Weis, C. Waloch, W. Seiche, B. Breit, J. Am. Chem. Soc.
2006, 128, 4188 – 4189; g) F. Chevallier, B. Breit, Angew. Chem.
2006, 118, 1629 – 1632; Angew. Chem. Int. Ed. 2006, 45, 1599 –
1602.
[
5] D. L. Kirschner, T. K. Green, F. Hapiot, S. Tilloy, L. Leclercq, H.
Bricout, E. Monflier, Adv. Synth. Catal. 2006, 348, 379 – 386.
6] A sulfonated phosphane was preferred to water-insoluble
Scheme 3. Platinum-catalyzed hydrogenation of 2-methyl-3-buten-2-ol
in water at room temperature with K [PtCl ] and 1·2 as catalyst.
2
4
[
phosphanes such as PPh , as we previously demonstrated that
3
the solubilization of such phosphanes using cyclodextrins in
aqueous bulk solution was impossible.
1
limitations and double-bond isomerization. First, H NMR
measurements were carried out to check that the reactant and
the product of the hydrogenation reaction were unable to
displace the phosphane from the CD cavity. Indeed, in the
reverse case, the 1·2 supramolecular bidentate structure
would be destroyed and the concept would be unusable.
Thus, 2-methyl-3-buten-2-ol or 2-methylbutan-2-ol was suc-
cessively mixed with aqueous solutions of 1·2 or a mixture of
[7] K. Matsumoto, Y. Nogushi, N. Yoshida, Inorg. Chim. Acta 1998,
72, 162 – 167.
2
[
8] L. Caron, M. Canipelle, S. Tilloy, H. Bricout, E. Monflier,
Tetrahedron Lett. 2001, 42, 8837 – 8840.
9] C. Binkowski-Machut, M. Canipelle, H. Bricout, S. Tilloy, F.
Hapiot, E. Monflier, Eur. J. Inorg. Chem. 2006, 1611 – 1619.
10] F. J. Ramos-Lima, A. G. Quiroga, J. M. PØrez, M. Font-Bardia,
X. Solans, C. Navarro-Ranninger, Eur. J. Inorg. Chem. 2003,
1591 – 1598.
[
[
3
, 4, and 5. As no variation in chemical shift could be detected,
[
11] M. L. Clarke, A. M. Z. Slawin, J. D. Woollins, Polyhedron 2003,
this clearly showed that the reactant and the product were
unable to interact with those species and that the 1·2
supramolecular complex remained stable under the exper-
imental conditions. Then, hydrogenation reactions were
performed with various amounts of 2. When 2 (2 equiv) was
mixed with 1 (1 equiv) and K [PtCl ] (1 equiv), no reaction
occurred (initial activity < 10 h ) regardless of the order in
which the components were added. Conversely, when the
brown precipitate that contained predominantly 4 was
22, 19 – 26.
[
12] E. W. Ainscough, A. M. Brodie, A. K. Burrell, A. Derwahl, G. B.
Jameson, S. K. Taylor, Polyhedron 2004, 23, 1159 – 1168.
13] F. Hapiot, S. Tilloy, E. Monflier, Chem. Rev. 2006, 106, 767 – 781.
14] F. J. Ramos-Lima, A. G. Quiroga, J. M. PØrez, M. Font-Bardia,
X. Solans, C. Navarro-Ranninger, Eur. J. Inorg. Chem. 2003,
1591 – 1598.
15] L. Caron, M. Canipelle, S. Tilloy, H. Bricout, E. Monflier, Eur. J.
Inorg. Chem. 2003, 595 – 599.
16] L. W. Francisco, D. A. Moreno, J. D. Atwood, Organometallics
[
[
2
4
À1
[
[
dissolved in water and used as a catalyst an initial activity of
2001, 20, 4237 – 4245.
À1
2
600 h was measured.
In summary, the cyclodextrin–phosphane assembly con-
stitutes a new class of supramolecular bidentate ligands. To
3
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2007, 46, 3040 –3042