Solid state and coordination compounds

Where do coordination compounds come in At several points in this text there have been discussed either molecular aggregates—Chapter 15 is devoted to them—or crystalline species. In this section some general points 

A different orientation of the crystal with respect to the magnetic field would lead to a different oscillation pattern and thus provide information on the topoloa of the Fermi surface (adapted from Ashcroft and Mermin). 

There are aspects of the discussion in the last paragraph which can be extended well beyond the compounds covered by the Robins and Day classification. Consider the following problem. NiO, when pure, is a pale solid. TiO and VO both have the same structure as NiO but are black and are almost metallic conductors of electricity, whereas NiO, when pure, is an insulator. That there is some electronic explanation for this pattern is made evident by the observation that when suitably doped with an impurity (Li20 is the one usually cited) NiO also becomes black and highly electrically 

Some generalizations have been made about those features which enhance the probability of band formation of the type just discussed in transition metal compounds  

the cation occurs early in the transition metal series  

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