Crystal field theory basic principles

Solvent extraction of metals embodies all aspects of coordination chemistry rates, equilibria, stereochemistry, crystal field theory, covalent bonding, hard-soft acid-base theory, hydrogen bonding, steric hindrance, enthalpy and entropy. All of these basic principles can link together to produce pure metals on an industrial scale from dilute aqueous solutions — a remarkable achievement of elegant coordination chemistry. To achieve this result it is only necessary to form within the aqueous medium a neutral species containing the metal to be extracted. 

Valence bond theory, while useful for describing the geometries of the complex ions, caimot explain other properties such as color and magnetism. Crystal field theory (CFT), a bonding model for transition metal complexes, accounts for these properties. To illustrate the basic principles of CFT, we examine the central metal atom s d orbitals in an octahedral complex. 

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