Ligand field theory, application

One way that molecular mechanics methods have been adapted to transition metal applications is by including one orbital-based term in the force field to describe the metal center. These terms are typically based on semiempirical methods or even some variation of ligand field theory. 

Real irreducible tensorial sets and their application to ligand field theory. S. E. Harnung and C. E. Schaffer, Struct. Bonding (Berlin), 1972,12, 257-295 (26). 

Gazquez JL (1993) Hardness and Softness in Density Functional Theory. 80 27-44 Gerloch M, Harding JH, Woolley RG (1981) The Context and Application of Ligand Field Theory. 46 1-46... 

Harnung SE, Schaffer CE (1972) Real Irreducible Tensorial Sets and their Application to the Ligand-Field Theory. 12 257-295... 

Warren KD (1984) Calculations of the Jahn-Teller Coupling Constants for d Systems in Octahedral Symmetry via the Angular Overlap Model. 57 119-145 Warren KD (1977) Ligand Field Theory off-Orbital Sandwich Complexes. 33 97-137 Warren KD (1976) Ligand Field Theory of Metal Sandwich Complexes. 27 45-159 Watson RE, Perlman ML (1975) X-Ray Photoelectron Spectroscopy. Application to Metals and Alloys. 24 83-132... 

Figgis, B. N.j Hitchman, M. A. Ligand field theory and its applications-, Wiley-VCH New York, 2000. 

B. N. Figgis, M. A. Hitchman, Ligand Field Theory and its Applications. Wiley-VCH, 2000. 

Although the application of elementary ligand field theory is adequate to explain many properties of complexes, there are other factors that come into play in some cases. One of those cases involves complexes that have structures that are distorted from regular symmetry. Complexes of copper(II) are among the most common ones that exhibit such a distortion. 

Several copper enzymes will be discussed in detail in subsequent sections of this chapter. Information about major classes of copper enzymes, most of which will not be discussed, is collected in Table 5.1 as adapted from Chapter 14 of reference 49. Table 1 of reference 4 describes additional copper proteins such as the blue copper electron transfer proteins stellacyanin, amicyanin, auracyanin, rusticyanin, and so on. Nitrite reductase contains both normal and blue copper enzymes and facilitates the important biological reaction NO) — NO. Solomon s Chemical Reviews article4 contains extensive information on ligand field theory in relation to ground-state electronic properties of copper complexes and the application of... 

The fact that the ligand field theory can account for the fractional character of the bond through the a parameter (cf. eq. 1.137 and 1.138) leads to important applications for covalent compounds, for which electrostatic theory is not adequate. 

An X-ray atomic orbital (XAO) [77] method has also been adopted to refine electronic states directly. The method is applicable mainly to analyse the electron-density distribution in ionic solids of transition or rare earth metals, given that it is based on an atomic orbital assumption, neglecting molecular orbitals. The expansion coefficients of each atomic orbital are calculated with a perturbation theory and the coefficients of each orbital are refined to fit the observed structure factors keeping the orthonormal relationships among them. This model is somewhat similar to the valence orbital model (VOM), earlier introduced by Figgis et al. [78] to study transition metal complexes, within the Ligand field theory approach. The VOM could be applied in such complexes, within the assumption that the metal and the... 

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