Allenylidenes: their multifaceted chemistry at rhodium

Abstract

Rhodium allenylidenes, which represent a class of ‘flat’ metallabutatrienes, are useful tools for the generation of metal-bound species that are hardly accessible (sometimes not accessible at all) by other synthetic routes. In contrast to various octahedral allenylidene metal complexes, e.g. of Cr⁰, Mn^I or Ru^II, the square-planar rhodium compounds trans- [RhX(=C=C=CRR′)(PPrⁱ₃) ₂] are attacked by both nucleophiles and electrophiles. Moreover, non-polar substrates such as H₂ or Cl₂ react cleanly with the title complexes to give products in which the allenylidene unit is preserved as part of a newly formed ligand. Attempts to prepare a square-planar cationic metallaheptahexaene, trans-[Rh(=C=C=CRR′)₂(PP r ⁱ₃)₂]⁺, unexpectedly led to the formation of two isomeric hexapentaenerhodium(I) complexes of which the isomer having the polyene coordinated in an unsymmetrical fashion is the thermodynamically more stable. C–C coupling reactions also occur on treatment of trans-[RhCl(=C=C=CPh₂)(PPrⁱ ₃)₂] with vinyl Grignard reagents or phenylacetylene leading to highly unsaturated RhC₅ and RhC₅P frameworks from which vinylallenes and phosphacumuleneylides are obtained.

References

1. K. H. Dötz, H. Fischer, P. Hofmann, F. R. Kreissl, U. Schubert and K. Weiss, Transition Metal Carbene Complexes, Verlag Chemie, Weinheim, 1983; Advances in Metal Carbene Chemistry, ed. U. Schubert, Kluwer Academic, Dordrecht, 1989.
2. E. O. Fischer and A. Maasböl, Angew. Chem., 1964, 76, 645; Angew. Chem., Int. Ed. Engl., 1964, 3, 580.
3. E. O. Fischer, Angew. Chem., 1974, 86, 651; Adv. Organomet. Chem., 1976, 14, 1.
4. J. P. Selegue, Organometallics, 1982, 1, 217 for an earlier variant of this preparative route see: H. Berke, Chem. Ber., 1980, 113, 1370.
5. M. I. Bruce, Chem. Rev., 1991, 91, 197.
6. H. Werner, Nachr. Chem. Tech. Lab., 1992, 40, 435; H. Werner, J. Organomet. Chem., 1994, 475, 45.
7. T. Rappert, O. Nürnberg, N. Mahr, J. Wolf and H. Werner, Organometallics, 1992, 11, 4156; H. Werner and T. Rappert, Chem. Ber., 1993, 126, 669.
8. H. Werner, T. Rappert, R. Wiedemann, J. Wolf and N. Mahr, Organometallics, 1994, 13, 2721.
9. For the preparation of 12 see: M. Laubender, Diploma Thesis, Universität Würzburg, 1995.
10. B. E. R. Schilling, R. Hoffmann and D. L. Lichtenberger, J. Am. Chem. Soc., 1979, 101, 585.
11. H. E. Bryndza and W. Tam, Chem. Rev., 1988, 88, 1163.
12. H. Werner, R. Wiedemann, M. Laubender, J. Wolf and B. Windmüller, Chem. Commun., 1996, 1413.
13. H. Werner, R. Wiedemann, N. Mahr, P. Steinert and J. Wolf, Chem. Eur. J., 1996, 2, 561.
14. T. Yoshida, T. Okano, Y. Ueda and S. Otsuka, J. Am. Chem. Soc., 1981, 103, 3411.
15. R. Wiedemann, Dissertation, Universität Würzburg, 1995.
16. R. Wiedemann, P. Steinert, O. Gevert and H. Werner, J. Am. Chem. Soc., 1996, 118, 2495.
17. R. Wiedemann, P. Steinert, M. Schäfer and H. Werner, J. Am. Chem. Soc., 1993, 115, 9864; R. Wiedemann, J. Wolf and H. Werner, Angew. Chem., 1995, 107, 1359; Angew. Chem., Int. Ed. Engl., 1995, 34, 1244.
18. H. Werner, N. Mahr, G. Frenking and V. Jonas, Organometallics, 1995, 14, 619.
19. N. M. Kostic and R. F. Fenske, Organometallics, 1982, 1, 974.
20. C. Busetto, A. D'Alfonso, F. Maspero, G. Perego and A. Zazetta, J. Chem. Soc., Dalton Trans., 1977, 1828; K. Wang, G. P. Rosini, S. P. Nolan and A. S. Goldman, J. Am. Chem. Soc., 1995, 117, 5082.
21. For a related, formally isoelectronic neutral ruthenium(II) species see: M. A. Esteruelas and H. Werner, J. Organomet. Chem., 1986, 303, 221.
22. H. Werner, A. Stark, P. Steinert, C. Grünwald and J. Wolf, Chem. Ber., 1995, 128, 49.
23. H. Werner, M. Laubender, R. Wiedemann and B. Windmüller, Angew. Chem., 1996, 108, 1330; Angew. Chem., Int. Ed. Engl., 1996, 35, 1237.
24. A. Höhn and H. Werner, J. Organomet. Chem., 1990, 382, 255; M. D. Fryzuk, L. Huang, N. T. McManus, P. Paglia, S. J. Rettig and G. S. White, Organometallics, 1992, 11, 2979.
25. H. Werner, D. Schneider and M. Schulz, J. Organomet. Chem., 1993, 451, 175; H. Werner, P. Schwab, N. Mahr and J. Wolf, Chem. Ber., 1992, 125, 2641.
26. L. Hagelee, R. West, J. Calabrese and J. Norman, J. Am. Chem. Soc., 1979, 101, 4888; P. J. Stang, M. R. White and G. Maas, Organometallics, 1983, 2, 720.
27. M. R. White and P. J. Stang, Organometallics, 1983, 2, 1654.
28. M. Laubender, O. Gevert and H. Werner, unpublished work.
29. H. Berke, P. Härter, G. Huttner and L. Zsolnai, Z. Naturforsch. B, 1981, 36, 929; N. E. Kolobova, L. L. Ivanov, O. S. Zhvanko, O. M. Khitrova, A. S. Batsanov and Yu. T. Struchkov, J. Organomet. Chem., 1984, 265, 271.
30. O. Nürnberg and H. Werner, J. Organomet. Chem., 1993, 460, 163.
31. M. Schäfer, N. Mahr, J. Wolf and H. Werner, Angew. Chem., 1993, 105, 1377; Angew. Chem., Int. Ed. Engl., 1993, 32, 1315.
32. P. Chow, D. Zargarian, N. J. Taylor and T. B. Marder, J. Chem. Soc., Chem. Commun., 1989, 1545.
33. R. L. Harlow, D. L. Thorn, R. T. Baker and N. L. Jones, Inorg. Chem., 1992, 31, 993; B. Windmüller, J. Wolf and H. Werner, J. Organomet. Chem., 1995, 502, 147.
34. H. Berke, Angew. Chem., 1976, 88, 684; Angew. Chem., Int. Ed. Engl., 1976, 15, 624.
35. R. W. Lass, Dissertation, Universität Würzburg, 1996.
36. H. Le Bozec, K. Ouzzine and P. H. Dixneuf, J. Chem. Soc., Chem. Commun., 1989, 219; D. Pilette, K. Ouzzine, H. Le Bozec, P. H. Dixneuf, C. E. F. Rickard and W. R. Roper, Organometallics, 1992, 11, 809; N. Pirio, D. Touchard and P. H. Dixneuf, J. Organomet. Chem., 1993, 462, C18.
37. V. Cadierno, M. P. Gamasa, J. Gimeno and E. Lastra, J. Organomet. Chem., 1994, 474, C27.
38. T. Braun, P. Meuer and H. Werner, Organometallics, 1996, 15 in the press.