Isomorphously Jahn-Teller distortion

There is agreement over the gross structural features of these linear chain chromium(II) complexes (and the isomorphous copper(II) analogues), but different models have been used for structural refinement. Phase transitions associated with the Jahn-Teller distortion (or to fi to y as the temperature is lowered) complicate the structural studies. 

In order to be sore that a distortion of a Cu compound, for example, is Jahn-Teller induced, a comparison with the isomorphous compounds with Zn or Ni is useful. These ions possess orbitally nondegenerate ground states in octahedral coordination and have nearly the same ionic radii as Cu. If the latter compounds contain Np- - and Zn in regular octahedral coordination, while the ligand enviromnent is strongly distorted in the case of Cu, the Jahn-Teller effect nmst be lespoimble for the symmetry reduction. 

An important aim of the book is then to show how common orbital situations arise throughout the whole chemical spectrum. For example, there are isomorphisms between the electronic structure of CHj, Fe(CO)4, and Ni(PRj)s and between the Jahn-Teller instability in cyclobutadiene and the Peierls distortion in solids, These relationships will be highlighted, and to a certain extent, we have chosen problems that allow us to make such theoretical connections across the traditional boundaries between the subdisciplines of chemistry,... 

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