Introduction Jahn-Teller distortion

The introduction of hydroxide as a unique ligand into the inner-coordination sphere of solvated Cu(II) should diminish Jahn-Teller distortion and notably decrease the rate of inner-sphere substitution. This presumably accounts for the fact that no evidence has been found for a unique contribution of the Cu2(OH)2 " ion in reactions involving solvated Cu(II) up to pH 5.8 [162]. (At higher pH, Cu(OH)2 precipitates.)... 

The spectroscopic properties that derive from these arguments for perfectly symmetrical antiaromatic systems are of limited practical interest since [4A/]annulenes are subject to Jahn-Teller and pseudo-Jahn-Teller distortions and do not have C symmetry in reality. What makes these results useful is that they provide a starting point for the introduction of perturbations that convert the parent perimeters into n systems of real interest. 

Affer the introduction of zinc info fhe spinel structure, there is no Jahn-Teller distortion since Zn + is in the 3di configuration. Similar to the effects of doping with lithium and magnesium, the Jahn-Teller effect is blocked, and cycling behavior improves. The reversible capacity of LiZno 05Mni95O4 remains at 102 mAh/g after 20 cycles. 

It seems natural to suppose that the tetragonal distortion of the tri-anion results from the Jahn-Teller effect. In order to study the problem more thoroughly we undertook recently the DFT calculations of this cluster as well as of several other hexanuclear rhenium chalcohalide clusters. The technical details of these calculations can be found in the original publication [8]. Here we only want to note that the introduction of relativistic corrections for Re atoms is crucial for the correct reproduction of the geometry of clusters. In our calculations, this was done by the zero order regular approximation (ZORA) Hamiltonian [9] within ADF 2000.02 package [10]. 

Consequently, the introduction of copper in the chrysotile stucture appears very difficult. This fact has already been pointed out by Wey et al. (ref. 16) and explained by a Jahn-Teller effect, which makes the structure distorted and creates an unstability for the whole crystal. 

---