Octahedral complexes valence bond description

The extended valence bond description of inner shell and outer shell bonding for octahedral cobalt(III) complexes, required as a result of different d-electron arrangements on the metal. The six empty hybridized orbitals can in each case accommodate six bonding lone pairs from six ligand donor atoms. 

Under what conditions are the molecular-orbital and valence-bond descriptions of the c bonding in an octahedral complex equivalent Derive the valence-bond functions shown in Fig. 9-7 from the general molecular-orbital functions. 

The sequence of energy levels obtained from a simple molecular orbital analysis of an octahedral complex is presented in Fig. 1-12. The central portion of this diagram, with the t2g and e levels, closely resembles that derived from the crystal field model, although some differences are now apparent. The t2g level is now seen to be non-bonding, whilst the antibonding nature of the e levels (with respect to the metal-ligand interaction) is stressed. If the calculations can be performed to a sufficiently high level that the numerical results can be believed, they provide a complete description of the molecule. Such a description does not possess the benefit of the simplicity of the valence bond model. 

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