Crystal Jahn-Teller effect

R. Englman, The Jahn-Teller effect in Molecules and Crystals, Wiley-1 nterscience. New York, 1972. 

R, Englman, The Jahn-Teller Effect in Molecules and Crystals, John Wiley. Sons, Inc., Interscience, New York, 1972 I, B. Bersucker and V. Z. Polinger, Vibronic Interactions in Molecules and Crystab, Springer Verlag, 1989. 

The Jahn-Teller effect in crystal chemistry and spectroscopy. I. B. Bersuker, Coord. Chem. Rev., 1975,14,357-412(105). 

Engleman, R., "The Jahn-Teller Effect in Molecules and Crystals", Wiley, New York, 1972. 

Some metal oxide structures are unstable when over-delithiated, and as a consequence, the crystal lattice collapses to form a new phase that is electrochemically inactive. Examples are the so-called Jahn—Teller effect for spinel cathodes and similar behavior for LiNi02 and LiCo02 materials as well. These irreversible processes are considered to be caused by the intrinsic properties of the crystalline materials instead of electrolytes and are, therefore, beyond the scope of the current review. See ref 46 for a detailed review. 

Ghose S., Kersten M., Langer K., Rossi G. and Ungaretti L. (1986). Crystal field spectra and Jahn-Teller effect of Mn in clinopyroxene and clinoamphiboles from India. Phys. Chem. Minerals, 13 291-305. 

In the following Table 12 there is also listed the compound K2NaMnFe, which is tetragonally distorted by the Jahn-Teller effect (Mn—F 4 X 1.86 A, 2 X 2.06 A) and crystallizes in the space group F4jmmm (200). 

A group of 8 ternary fluorides containing the transition metal ions Cr2+ and Cu + crystallizes in a tetragonedly distorted perovskite lattice. This distortion is caused by the Jahn-Teller effect displayed by the configurations d% d (Cr +) and d d (Cu2+) resp., rather than by geometrical reasons. As for their space requirements the ions Cr + and Cu + are very close in size to Mn2+ and Co + resp. and as a consequence the corresponding compounds do not differ in their tolerance factors. 

In the following Table 27 two compounds, NaCuFs (271) and NaCrFs (316), both distorted by the Jahn-Teller effect, have been listed also. They are isostructural with each other and crystallize monoclinicly, but are closely related to the GdFeOs-type. Probably the Jahn-Teller distortion elongates the MeFe-octahedra, as stated in the corresponding compounds Na2MeF4 (page 35). 

Considering the influence of electronic configurations on crystal structures it may be asked, whether certain structure t5rpes are restricted to fluorine compounds of the transition elements. Apart from the structure types distorted by the Jahn-Teller effect such a limitation is not obvious at all. On the contrary quite a number of structure prototypes are represented by compounds of the main group elements. Bonding thus must be similar in both, main group and transition element fluorides, at least as for the factors that influence crystal structmes. 

Englman, R. (1972) The Jahn-Teller Effect in Molecules and Crystals, Wiley, London. Etemad, S., Heeger, A. J. MacDiarmid, A. G. (1982) Ann. Rev. Phys. Chem. 33,443. Eyring, L. (1974) in Solid State Chemistry ed. Rao, C. N. R.) Marcel Dekker, New York. Eyring, L. (1979) in Handbook on the Physics and Chemistry of Rare Earths (eds Gschneidner Jr, K. A. Eyring, L.) North-Holland, Amsterdam. 

Englman R. (1972). The Jahn-Teller Effect in Molecules and Crystals, Chap. II. Wiley, London. Englman, R. (1977). J. Chem. Phys. 66, 2212. 

Jahn-Teller Effect. With the exception of d3, d5, and d8 configurations, the ground state in an octahedral crystal field is still orbitally degenerate. Some of this degeneracy is removed by the spin-orbit interaction. 

TL OEt) ]224 with distortions due to M—M bonding. Crystal structure analysis of [W4(OEt)i6] (Figure 22) reveals the presence of two short W—W bonds (2.645 and 2.76 A) and two long bonds of 2.93 A. In this structure, there is a total of five possible W—W interactions, and thus, to form five bonds of order one, ten electrons are required. Only eight metal electrons are available for metal-metal bonding, which leads to the observed distortions. It has been suggested that this distortion results from a novel second order Jahn-Teller effect.225... 

R. Engelman, The Jahn-Teller Effect in Molecules and Crystals , Wiley-Interscience, London, 1972. 

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