Single-site catalysts on a cylindrical support beyond nanosize

Organometallics

Volumn 22, Issue 21, 2003, Pages 4175-4177

  Suijkerbuijk, Bart M J M ^a   Shu, Lijin ^b   Gebbink, Robertus J M Klein ^a   Schlüter, A Dieter ^b   Van Koten, Gerard ^a  

^a UTRECHT UNIVERSITY   (Netherlands)

^b FREIE UNIVERSITÄT BERLIN   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

CHEMICAL ANALYSIS; COMPLEXATION; CONDENSATION; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; PALLADIUM; PLATINUM; POLYMERS; SYNTHESIS (CHEMICAL);

ALDOL CONDENSATION; BENZALDEHYDE; DENDRONIZED POLYMERS; ELEMENTAL ANALYSIS; METHYL ISOCYANOACETATE;

CATALYSTS;

EID: 0142258794     PISSN: 02767333     EISSN: None     Source Type: Journal    
DOI: 10.1021/om034078a     Document Type: Article

References (24)

1. (a) Bosman, A. W.; Janssen, H. M.; Meijer, E. W. Chem. Rev. 1999, 99, 1665-1688.
2. (b) Fischer, M.; Vögtle, F. Angew. Chem., Int. Ed. 1999, 38, 884-905.
3. (c) Hecht, S.; Fréchet, J. M. J. Angew. Chem., Int. Ed. 2001, 40, 74-91.
4. (d) Grayson, S. M.; Fréchet, J. M. J. Chem. Rev. 2001, 101, 3819-3868.
5. (a) Sheiko, S. S.; Möller, M. Chem. Rev. 2001, 101, 4099-4123.
6. (b) Hawker, C. J.; Bosman, A. W.; Harth, E. Chem. Rev. 2001, 101, 3661-3688.
7. (c) Hedrick, J. L.; Magbitang, T.; Connor, E. F.; Glauser, T.; Volksen, W.; Hawker, C. J.; Lee, V. Y.; Miller, R. D. Chem. Eur. J. 2002, 8, 3308-3319.
8. (a) Schlüter, A. D.; Rabe, J. P. Angew. Chem., Int. Ed. 2000, 39, 865-883.
9. (b) Zhang, A.; Shu, L.; Bo, Z.; Schlüter, A. D. Macromol. Chem. Phys. 2003, 328-339.
10. (a) Shu, L.; Schäfer, A.; Schlüter, A. D. Macromolecules 2000, 33, 4321-4328.
11. (b) Shu, L.; Schlüter, A. D. Ecker, C.; Severin, N.; Rabe, J. P. Angew. Chem., Int. Ed. 2001, 40, 4666-4669.
12. (c) Shu, L.; Gössl, I.; Rabe, J. P.; Schlüter, A. D. Macromol. Chem. Phys. 2002, 2540-2550.
13. (d) Gössl, I.; Shu, L.; Schlüter, A. D.; Rabe, J. P. J. Am. Chem. Soc. 2002, 124, 6860-6865.
14. Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 40, 3750-3781.
15. The platinum compounds were initially prepared because of their robustness and in order to optimize the coupling conditions. The palladium analogues, however, are of interest from a catalytic point of view. Experimental details for the syntheses of PG1PdBr, PG2PdBr, PG3PdBr, PG1PtCl, PG2PtCl, and PG3PtCl as well as their full characterization data are given in the Supporting Information.
16. Suijkerbuijk, B. M. J. M.; Slagt, M. Q.; Klein Gebbink, R. J. M.; Lutz, M.; Spek, A. L.; Van Koten, G. Tetrahedron Lett. 2002, 43, 6565-6568.
17. 2 binding to occur: (a) Terheijden, J.; van Koten, G.; Mul, W. P.; Stufkens, D. J.; Muller, F.; Stam, C. H. Organometallics 1986, 5, 519-525.
18. 8 metal binding and the resulting induced coloration are specific for the NCN-platinum halide and -nickel halide compounds.
19. Upon treatment of PGnPdBr with a silver-based dehalogenating agent, the silver halide formed could not be separated from the dehalogenated product. Recently, however, we discovered that NCN-palladium halide complexes catalyze this aldol condensation reaction, albeit with lower initial rates than for their "activated" cationic analogues. Actually, one molecule of methyl isocyanoacetate inserts into the palladium-carbon bond and a second one displaces one amino ligand. (Zografidis, A.; Polborn, K.; Beck, W.; Markies, B.; van Koten, G. Z. Naturforsch. 1994, 49b, 1494-1498). This insertion reaction may furthermore account for the drop in catalytic activity during the second run, due to a decreased stability of the organometallic moiety with a C,N-bidentate coordination geometry with respect to that of one with a N,C,N′-tridentate coordinate geometry. Cf.: Mehendale, N.; Klein Gebbink, R. J. M.; van Koten, G. Manuscript in preparation.
20. Negative effects of active site proximity have earlier been observed by us for dentritic catalysts derived from a single-site homogeneous catalyst: (a) Kleij, A. W.; Gossage, R. A.; Jastrzebski, J. T. B. H.; Boersma, J.; van Koten, G. Angew. Chem., Int. Ed. 2000, 39, 176-178.
21. (b) Kleij, A. W.; Gossage, R. A.; Klein Gebbink, R. J. M.; Brinkmann, N.; Reijerse, E. J.; Lutz, M.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 2000, 122, 12112-12214.
22. This contrasts with the behavior of the end groups of regular dendrimers, which have a more globular, three-dimensional (and thus larger) space at their disposal, whereas the DenPol end groups have one dimension less (namely a two-dimensional disklike space); Karakaya, B.; Claussen, W.; Gessler, K.; Saenger, W.; Schlüter, A. D. J. Am. Chem. Soc. 1997, 119, 3296-3301.
23. For a review on dendrimer-encapsulated cataysts, see: Twyman, L. J.; King, A. S. H.; Martin, I. K.; Chem. Soc. Rev. 2002, 31, 69-82.
24. For very recent, comprehensive reviews on "conventional" polymer- and dendrimer-supported catalysts, see: Recoverable Catalysts and Reagents. Chem. Rev. 2002, 102 (Gladysz, J. A., Ed.).