Jahn-Teller structural distortions

Butterfly. While Tl2Te22- has a (2)(1) + (2)(4) + 2 = 12 skeletal electron count isoelectronic and isolobal with neutral cyclobutadiene, it undergoes a different Jahn-Teller-like distortion to the butterfly structure discussed by Bums and Corbett [81]. 

Cyclopentadienyl radicals are likely to experience Jahn-Teller-type distortion from planarity. The pentafluorocyclopentadienyl radical C5F 5214 was obtained by photolytic dissociation of the chlorine atom of C5F5C1. The fluorine hyperfine structure (A1S0 = 16 G)... 

As we have seen in Sect. 2. the molecular Jahn-Teller effect distorts the molecule into either or Ds symmetry. It is not impossible to place such distorted anions in a lattice so that the overall symmetry remains tetragonal, but the main axis of these distortions cannot coincide with the principal crystallographic axis of the A4C60 crystals. In line with the suggestions by Fabrizio and Tosatti [16], the main distortion axis of the molecule could be disordered or ordered in some way, but the average structure has to be that found by diffraction. 

The Jahn-Teller theorem indicates that when a degenerate shell is not completely filled, a distortion away from spherical symmetry occurs, leading to a loss of degeneracy. The splitting pattern produced by the Jahn-Teller type distortion is identical to that predicted by the crystal field approach used in the structural jellium model. 

Li2[Mn2]04 induces a crystallographic Jahn-Teller (tetragonal) distortion in the spinel structure, which is a consequence of the increased number of (d" ) ions... 

There are many electronically driven structural distortions that meet the spirit but not the letter of the Jahn-Teller theorem, because they do not possess a partially occupied HOMO. These distortions are often referred to as 2nd order Jahn-Teller (SOJT) distortions. Formally, a SOJT is defined as a structural distortion arising from a 2nd order energy change in the HOMO [32]. While, in principle, almost... 

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