Crystal field theory applications

See discussion by W. Moffitt and C. J. Ballhauscn, Ann. Rev. Phys. Ou rn.f 7, 107 (1956), for a summary of what has become popularly referred to as crystal field theory. Applications to inorganic chemistry will be found in F. Basolo and R. G. Pearson, Mechanisms of Inorganic Reactions, John Wiley Sons, Inc., New York, 1958. 

Much useful understanding of the processes of crystal-field theory, however, can be had from a study of just the free-ion ground terms. Application of the simple process in Section 3.7 identifies the ground terms for d free ions as D, D,... 

Burns, R. G. Mineralogical Applications of Crystal Field Theory, Cambridge University Press New York, 1970, 1993 p 22. 

Figure 1,17 Absorption spectrum of a forsteritic olivine under polarized light. Ordinate axis represents optical density (relative absorption intensity, ///q). From R. G. Burns (1970), Mineralogical Applications of Crystal Field Theory. Reprinted with the permission of Cambridge University Press.

Nevertheless, the application of crystal field theory to natural compounds... 

The Jahn-Teller principle finds applications both in the framework of crystal field theory and in the evaluation of energy levels through the LCAO-MO approach. In both cases, practical apphcations are restricted to 3d transition elements. 

Burns R. G. (1970). Mineralogical Application of Crystal Field Theory Cambridge University Press, Cambridge. 

Crystal Field Theory (CFT) has also been used considerably to rationalize visible absorption spectra, hydration energies, stabilities of complexes, rates and mechanism of reaction, and redox potentials of transition element ions. These applications of CFT are summarized in a book by Basolo and Pearson 1B6). 

We may anticipate an eventual consensus on the amount and place of symmetry in the chemistry curriculum, but for now we have assumed no prior background in the subject- We have thus tried to illustrate a wide variety of uses of symmetry without delving deeply into the background theory. We hope that those new to the topic can find a useful introduction to the application of symmetry to problems in inorganic chemistry. On the other hand, those having previous experience with the subject may wish to use this chapter as a brief review. And, recognizing that things are in a state of flux, we have attempted to make it possible to study various topics such as orbital overlap, crystal field theory, and related material, as in the past, with minimal reference to symmetry if desired... 

Applications of Among the early successes of crystal field theory was its ability to account for... 

The foregoing discussion of valence is. of course, a simplified one. From ihe development of the quantum theory and its application to the structure of the atom, there has ensued a quantum theory of valence and of the structure of the molecule, discussed in this hook under Molecule. Topics thal are basically important to modem views of molecular structure include, in addition to those already indicated the Schroedinger wave equation the molecular orbital method (introduced in the article on Molecule) as well as directed valence bonds bond energies, hybrid orbitals, the effect of Van der Waals forces and electron-dcticiem molecules. Some of these subjects are clearly beyond the space available in this book and its scope of treatment. Even more so is their use in interpretation of molecular structure. [However, sec Crystal Field Theory and Ligand.)... 

Crystal field theory is one of several chemical bonding models and one that is applicable solely to the transition metal and lanthanide elements. The theory, which utilizes thermodynamic data obtained from absorption bands in the visible and near-infrared regions of the electromagnetic spectrum, has met with widespread applications and successful interpretations of diverse physical and chemical properties of elements of the first transition series. These elements comprise scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper. The position of the first transition series in the periodic table is shown in fig. 1.1. Transition elements constitute almost forty weight per cent, or eighteen atom per cent, of the Earth (Appendix 1) and occur in most minerals in the Crust, Mantle and Core. As a result, there are many aspects of transition metal geochemistry that are amenable to interpretation by crystal field theory. 

The major focus of the book is on mineral crystal structures that provide an ordered array of anions forming coordination polyhedra around the central cations. The thermodynamic data underlying many of the geochemical applications described in the first ten chapters are derived from energies of absorption bands in the optical spectra of minerals, which are most simply explained by crystal field theory. Use of experimentally determined energy level data rather than energy separations computed in molecular orbital diagrams is the emphasis of these early chapters. 

Bums, R. G., Clark, R. H. Fyfe, W. S. (1964) Crystal field theory and applications to problems in geochemistry. In Chemistry of the Earth s Crust, Proceedings of the Vernadsky Centennial Symposium. (A. P. Vinogradov, ed. Science Press, Moscow), 2, 88-106. [Transl.-. Israel Progr. Sci. Transl., Jerusalem, pp. 93-112 (1967).]... 

Perhaps a more fundamental application of crystal field spectral measurements, and the one that heralded the re-discovery of crystal field theory by Orgel in 1952, is the evaluation of thermodynamic data for transition metal ions in minerals. Energy separations between the 3d orbital energy levels may be deduced from the positions of crystal field bands in an optical spectrum, malting it potentially possible to estimate relative crystal field stabilization energies (CFSE s) of the cations in each coordination site of a mineral structure. These data, once obtained, form the basis for discussions of thermodynamic properties of minerals and interpretations of transition metal geochemistry described in later chapters. 

One of the most successful applications of crystal field theory to transition metal chemistry, and the one that heralded the re-discovery of the theory by Orgel in 1952, has been the rationalization of observed thermodynamic properties of transition metal ions. Examples include explanations of trends in heats of hydration and lattice energies of transition metal compounds. These and other thermodynamic properties which are influenced by crystal field stabilization energies, including ideal solid-solution behaviour and distribution coefficients of transition metals between coexisting phases, are described in this chapter. 

Bums, R. G. (1965a) Electronic Spectra of Silicate Minerals Applications of Crystal Field Theory to Aspects of Geochemistry. Ph.D. Diss., Univ. Calif. Berkeley, California. 

Curtis, C. D. (1964) Applications of the crystal-field theory to the inclusion of trace transition elements in minerals during magmatic differentiation. Geochim. Cosmochim. Acta, 28, 389-403. 

Mineralogical applications of crystal field theory, Second Edition ROGER G. BURNS... 

Burns, Roger G (Roger George), 1937-Mineralogical applications of crystal field theory/Roger G. Bums. - 2nd ed. p. cm. - (Cambridge topics in mineral physics and chemistry 5)... 

The choice of topics is largely governed by the author s interests. Following a brief introduction the crystal field model is described non-mathematically in chapter 2. This treatment is extended to chapter 3, which outlines the theory of crystal field spectra of transition elements. Chapter 4 describes the information that can be obtained from measurements of absorption spectra of minerals, and chapter 5 describes the electronic spectra of suites of common, rock-forming silicates. The crystal chemistry of transition metal compounds and minerals is reviewed in chapter 6, while chapter 7 discusses thermodynamic properties of minerals using data derived from the spectra in chapter 5. Applications of crystal field theory to the distribution of transition elements in the crust are described in chapter 8, and properties of the mantle are considered in chapter 9. The final chapter is devoted to a brief outline of the molecular orbital theory, which is used to interpret some aspects of the sulphide mineralogy of transition elements. 

These groups are complex groups and find application in quantum chemistry or in Crystal Field theory and Ligand Field theory that too in a different format. 

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