Chapter 2 Organolanthanide Compounds

Frank T. Edelmanna and Peter Porembab

a Chemisches Institut der Otto-von-Guericke Universität, Universitätsplatz 2, D-39106 Magdeburg, Germany

b Institut für Anorganische Chemie der Universität Göttingen, Tammannstraße 4, D-37077 Göttingen, Germany

With contributions from:
Andersen, R. A., Berkeley
Atwood, J. L., Columbia
Basalgina, T. A., Nizhny Novgorod
Bercaw, J. E., Pasadena
Bertolini, G., Milano
Birmingham, J. M., London
Bloom, I., Irvine
Bochkarev, M. N., Nizhny Novgorod
Booiji, M., Groningen
Bruin, P., Groningen
Bruncks, N., Berlin
Bums, C. J., Berkeley
Caro, P. E., Meudon Bellevue
Cesca, S., Milano
Chen, W., Changchun
Choi, H. W., Irvine
Ciliberto, E., Catania
Cloke, F. G. N., Brighton
Cosgriff, J. E., Clayton
Day, C. S., Lincoln
Day, V. W., Lincoln
de Boer, E. J. M., Amsterdam
de Boer, J. L., Groningen
Deacon, G. B., Clayton
Deming, T. J., Irvine
den Haan, K. H., Groningen
Dietrich, A., Berlin
Doedens, R. J., Irvine
Dubeck, M., Detroit
Edelmann, F, T., Göttingen
Emelyanova, N. S., Nizhny Novgorod
Ernst, R. D., Salt Lake City
Evans, W. J., Irvine
Fan, B., Changchun
Fedorova, E. A., Nizhny Novgorod
Fischer, R. D., Hamburg
Forsyth, C. M., Clayton
Fragalà, I., Catania
Girard, P., Orsay
Görlitz, F. H., Berlin
Grate, J. W., Irvine
Greco, A., Milano
Grynkewich, G. W., Evanston
Hanusa, T, P., Irvine
Hayes, R. G., Notre Dame
Hays, G. R., Groningen
Heeres, H. J., Groningen
Herbst-Irmer, R., Göttingen
Herskovitz, T., Wilmington
Hitchcock, P. B., Brighton
Hodgson, K. O., Berkeley
Howard, J. A. Κ., Durham
Huang, Y., Shanghai
Hughes, L. A., Irvine
Huis, R., Amsterdam
Hunter, W. E., University
Jamerson, J. D., Edmonton
Jin, S. C., Changchun
Jin, Z., Changchun
Kagan, H. B., Orsay
Kalinina, G. S., Nizhny Novgorod
Ke, W., Changchun
Kiers, N. H., Groningen
Kilimann, U., Göttingen
Kinsley, S. A., Berkeley
Köhn, R. D., Berlin
Kojic-Prodic, B., Zagreb
Koplick, A. J., Clayton
Lappert, M. F., Brighton
Lauke, H., Berlin
Lawrenz, E. T., Clayton
Levan, K. R., Irvine
Lin, Y., Changchun
Maginn, R. E., Detroit
Manastyrskyj, S., Detroit
Mares, F., Berkeley
Marks, T. J., Evanston
Masino, A. P., Edmonton
Meadows, J. H., Irvine
Meese-Marktscheffel, J. A., Berlin
Meetsma, A., Groningen
Müller, J., Berlin
Namy, J. L., Orsay
Noltemeyer, M., Göttingen
Orpen, A. G., Bristol
Oskam, A., Amsterdam
Pain, G. N., Clayton
Parshall, G., W., Wilmington
Pasman, P., Amsterdam
Peterson, T., T., Irvine
Pickardt, J., Berlin
Prashar, S., Brighton
Qi, G. Z., Changchun
Qian, C., Shanghai
Raymond, K. N., Berkeley
Razuvaev, G. A., Nizhny Novgorod
Recknagel, A., Göttingen
Reier, F.-W., Berlin
Renkema, J., Groningen
Rigsbee, J. T., Berkeley
Roe, C., Wilmington
Ruben, H., Berkeley
Schäfer, M., Göttingen
Schaverien, C. J., Amsterdam
Schmidt, H.-G., Göttingen
Schumann, H., Berlin
Sheldrick, G. M., Göttingen
Shen, Q., Changchun
Singh, A., Brighton
Smith, R. G., Brighton
Spek, A. L., Utrecht
Spencer, B., Berkeley
Stalke, R., Göttingen
Starks, D. F., Berkeley
Steudel, A., Hamburg
Streitwieser, Jr., A., Berkeley
Stults, S. D., Berkeley
Takats, J., Edmonton
Templeton, D. H., Berkeley
Teuben, J. H., Groningen
Thomas, J. L., Fullerton
Thompson, M. E., Pasadena
Tilley, T. D., Berkeley
Trakampruk, W., Salt Lake City
Trifonov, A. A., Nizhny Novgorod
Tuong, T. D., Clayton
Ulibarri, T. A. Irvine
van der Heijden, H., Amsterdam
Vollmer, S. H., Lincoln
Watson, P. L., Wilmington
Wayda, A. L., Irvine
Wilkinson, D. L., Clayton
Wilkinson, G., London
Xie, Z., Shanghai
Zalkin, A., Berkeley
Zhang, H., University
Ziller, J. W., Irvine

2.1 Introduction

2.2 Organolanthanide(0) Complexes

2.3 Organolanthanide(II) Complexes

2.4 Organolanthanide(III) Complexes

2.5 Organolanthanide(IV) Complexes

2.1 Introduction

Organolanthanide chemistry is an area of vigorous development. The number of stable though highly reactive organolanthanide complexes continues to increase at a rapid rate.1–4 However, in several points organolanthanide chemistry differs significantly from the organometallic chemistry of the d-block transition elements. The following general principles can be noted:

1. The bonding in organolanthanide complexes is considered to be predominantly ionic. Thus, there is a strong preference for anionic ligands such as cyclopentadienyl, cyclooctatetraenyl, alkoxides, etc. In fact, the vast majority of all organolanthanide complexes described so far contain cyclopentadienyl and related ligands. This situation is reflected by the choice of preparations in the following chapter.
2. According to Pearson′s HSAB concept the lanthanide ions are hard acids. Stable coordination compounds are generally formed with hard donor ligands which coordinate through oxygen or nitrogen atoms. Coordination compounds containing soft donor ligands bonded via S, Se, Te, P, or As atoms are less frequently observed.
3. Lanthanide ions show little affinity for neutral π-donor ligands. Several classes of coordination compounds which are well known for the c/-block transition metals are virtually unknown for the rare earth elements. Typical examples are metal carbonyls or complexes containing neutral olefins, dienes, or alkynes. Only a few stable complexes with π-interactions between lanthanide ions and neutral arenes have been described.
4. The rare earth elements show a strong tendency to adopt high coordination numbers. Formal coordination numbers in organolanthanide complexes usually fall in the range between 7 and 9, although even higher coordination numbers are possible. Low coordination around lanthanide atoms (coordination numbers ranging from 3 to 6) can be achieved by the use of sterically demanding ligands. In general, steric factors play a much more important role in organolanthanide chemistry than the electron count. Coordinative unsaturation is the main reason for the often encountered formation of solvated species or “ate” complexes. In many cases alkali metal halides formed during a reaction are retained in the product in order to increase the coordination number around the metal atom.
5. With only a few exceptions, the lanthanide ions in their +2 and +3 oxidation states are paramagnetic. However, due to the effective shielding of the ƒ orbitals the 1H NMR spectra of organolanthanide complexes are often well interpretable and exhibit sharp though strongly shifted peaks. The group 3 elements scandium, yttrium, and lanthanum as well as divalent ytterbium are accessible to heteronuclear NMR spectroscopy (45Sc, 89Y, 139La, 171Yb).
6. Lanthanide elements have an extremely high affinity for oxygen. Not surprisingly, organolanthanide chemistry is also strongly influenced by the oxophilic nature of the rare earth metals. As a consequence, all organolanthanide complexes are highly air- and water-sensitive and must be handled under rigorous exclusion of oxygen and moisture. Unless otherwise stated, all operations described in this chapter are carried out under purified (BASF 3/11 oxygen-removal “catalyst” and molecular sieves and/or Sicapent) nitrogen or argon using Schlenk tube or drybox techniques, and all glassware should be thoroughly dried prior to use. All solvents must be carefully dried using sodium/benzophenone (diethyl ether, THF, toluene, hexane, pentane) and freshly distilled under nitrogen before use. For the removal of finely divided alkali metal halide precipitates the use of Celite filter aids is highly recommended. A good introduction to the techniques involved in preparation and handling of organolanthanide complexes is given in ref.5

References

1 F. T. Edelmann, in: Comprehensive Organometallic Chemistry II, (E. W. Abel, F. G. A. Stone, G. Wilkinson, eds.), Vol. 4, Pergamon Press, London, 1995.

2 H. Schumann, J. A. Meese-Marktscheffel, L. Esser, Chem. Rev. 95, 865 (1995).

3 R. D. Köhn, G. Kociok-Köhn, H. Schumann, in: Encyclopedia of Inorganic Chemistry, (R. B. King, ed.), Wiley, London, New York, 1994.

4 C. J. Schaverien, Adv. Organomet. Chem. 36, 283 (1994).

5 A. I. Wayda, M. Y. Darensbourg, (eds.), Experimental Organometallic Chemistry: A Practicum in Synthesis and Characterization, ACS Symposium Series No. 357, American Chemical Society, Washington, 1987.

2.2 Organolanthanide(0) Complexes

Bis(η6-1,3,5-tri-tert.-butylbenzene) Complexes of Dysprosium(0) and Holmium(0) — [(η6-1,3,5-t-Bu3(C6H3)2]Ln(0) (Ln = Dy, Ho)

F. Geoffrey N. Cloke

School of Chemistry and Molecular Sciences, University of Sussex, Brighton BNl 9QJ, U.K.

The preparation of bis(η6-arene)lanthanide...