f electron systems: the lanthanides and actinides
In recent years there has been an increasing study of compounds of the lanthanides and, to a lesser extent, of the actinides. These two groups of elements have varying numbers of electrons in their f orbitals (4f for the lanthanides and 5f for the actinides), thus inviting a comparison with the transition metal elements, discussed in Chapters 6–9, with their varying number of d electrons. However, as we shall see, such a comparison is not particularly helpful, a situation which has contributed to an attitude commonly encountered—that f electron systems are difficult to understand, that the theory is difficult. It is hoped that it will be possible to demonstrate in this chapter that this is not the case. Indeed, it is hoped to convince the reader that a study of f electron systems is not only of value in its own right but that such a study helps in the understanding of d electron systems. It does this by its concern with phenomena which also exist in d electron systems but which are currently largely ignored when discussing them.
KeywordsAngular Momentum Electron System Crystal Field Orbital Angular Momentum Spin Multiplicity
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- A good, if at some points rather dated, survey is Complexes of the Rare Earths,S. P. Sinha, Pergamon, Oxford, 1966. An excellent recent account of the chemistry of the lanthanides and actinides is to be found in Lanthanides and Actinides,S. Cotton, Macmillan, London, 1991. An excellent series of brief review articles is to be found in Radiochim. Acta (1993) 61. Three examples are `Overview of the Actinide and Lanthanide (the f) Elements’ by G. T. Seaborg (p 115), `Systematics of Lanthanide Coordination’ by E. N. Rizkalla (p 118) and, for those who are interested in learning how to study the chemistry of a couple of dozen atoms, ‘Atom-at-a-Time Chemistry’ by D. C. Hoffman (p 123).Google Scholar
- The shapes of f orbitals is discussed in readable fashion in two adjacent papers: H. G. Friedman, G. R. Choppin and D. G. Feuerbacher, J. Chem. Educ. (1964) 41, 354, and C. Becker, J. Chem. Educ. (1964) 41, 358. See also C. A. L. Becker, J. Chem. Educ. (1979) 56, 511, and O. Kikuchi and K. Suzuki, J. Chem. Educ. (1985) 62, 206.CrossRefGoogle Scholar
- For spectra, a useful compilation is Spectra and Energy Levels of Rare Earth Ions in Crystals,G. H. Dieeke, Interscience, New York, 1968. Particularly valuable is an article `Optical Properties of Actinide and Lanthanide Ions’ by J. P. Hessler and W. T. Carnal] in the American Chemical Society Symposium Series, 1980, Vol 131, 349. The interpretation goes well beyond the content of the present chapter but the article contains energy level diagrams and other very useful and accessible data.Google Scholar
- Many of the topics touched on in this chapter are treated in more detail and depth in some issues of Structure and Bonding,notably 13, 22, 25, 30 and 59/60(actinides). A reference that contains more than its title indicates is `Lanthanide Ion Luminescence in Coordination Chemistry and Biochemistry’, W. D. Horrocks and M. Albin, Prog. Inorg. Chem. (1984) 31,1.Google Scholar
- Two articles that provide an overview of the current situation on f orbital involvement in bonding in the actinides are: Cyclopentadienyl-Actinide Complexes: Bonding and Electronic Structure’ by B. E. Bursten and R. J. Strittmatter, Angew. Chem. Int. Ed. (1991) 30, 1069 (in its last couple of pages this provides a brief overview of all the theoretical methods being employed) and `The Electronic Structure of Actinide-Containing Molecules: A Challenge to Applied Quantum Chemistry’ by M. Pepper and B. E. Bursten, Chem. Rev. (1991) 91, 719. A reference given at the end of Chapter 6 is also relevant, although some of the relevant articles are more readable than others The Challenge of d and f Electrons, D. R. Salahub and M. C. Zerner (eds.) American Chemical Society Symposium Series, 1989, Vol. 394.Google Scholar