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Jahn-Teller influence

A particularly interesting case is when a set of hydrogens which are chemically equivalent in the unionized molecule become inequivalent in the positive ion. Obvious examples are Jahn-Teller active molecules, but the same phenomenon may be found also in Jahn-Teller inactive systems. Since deuteration fcr practical reasons must be done before ionization, it may happen that a single deuterated molecule may produce several inequivalent isomers of the radical cation, e.g., upon irradiation. This will obviously influence the recorded ESR spectrum. [Pg.340]

A dominant influence of certain electronic configurations on the structure type is represented by the Jahn-Teller effect (173). It shall be discussed here only briefly. For further information the reader is referred to a review by Or gel and Dunitz (241) and as for the general base of ligand field theory to the books of Orgel (240) and Figgis (101). [Pg.62]

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. [Pg.63]

Fig. 7. The influence of the Jahn-Teller effect on bond lengths (A) of copper sulfate trihydrate (top) and pentahydrate (bottom). Note that in the trihydrate one of the Cu(II)-"OSOs bonds is short so that all equatorial Cu(Il)-"0 bonds are 1.94-1.98 A, while the axial bonds are 2.40-2.45 A. Fig. 7. The influence of the Jahn-Teller effect on bond lengths (A) of copper sulfate trihydrate (top) and pentahydrate (bottom). Note that in the trihydrate one of the Cu(II)-"OSOs bonds is short so that all equatorial Cu(Il)-"0 bonds are 1.94-1.98 A, while the axial bonds are 2.40-2.45 A.
IX. Difficult Metals Jahn-Teller Effects in Cu(II) and the trans Influence in Pt(II)... [Pg.1]

For those systems we have studied so far, many classical ligand field features are successfully captured by LFMM e.g., the double hump variation of structural and thermodynamic properties due to the LFSE (73), o- (36,58,78) and -type (77) Jahn-Teller effects, the trans influence (21), and spin state effects (18,33,59). LFMM is equally at home with small molecules and large proteins and potential future coordination chemistry applications are enormous. [Pg.36]

Because the kinetic energy dissipation of an excess electron by surrounding water molecules plays an essential role during the formation of electron-radical pairs, the influence of the quantum polarization of water molecules and OH radical must be investigated in detail. Further experimental studies on the short-time dependence of vibronic couplings in aqueous environment would permit to understand the contribution of Jahn-Teller effects on the crossing of an elementary redox reaction with OH radical. [Pg.236]

In these molecular type lattices the structure of the CuN402 chromophore is independent of the structure of the host lattice, and the effect is referred to as the noncooperative Jahn-Teller effect.514 It applies to the vast majority of low symmetry copper(II) complexes involving organic type ligands, but even here cooperative effects that influence the ESR properties, such... [Pg.705]

The site preferences shown by cations in the spinel structure demonstrate that transition metal ions prefer coordination sites that bestow on them greatest electronic stability. In addition, certain cations deform their surrounding in order to attain enhanced stability by the Jahn-Teller effect. These two features suggest that similar factors may operate and cause enrichments of cations in specific sites in silicate structures, leading to cation ordering or intersite (intracrystalline ) partitioning within individual minerals which, in turn, may influence distribution coefficients of cations between coexisting phases. [Pg.250]


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