Jahn-Teller effect dynamic

The high lability of cP [Cu(H20)6]2+ is coincident with the operation of a dynamic Jahn-Teller effect which causes its tetragonal distortion to randomly reorientate, or invert, about the x, y, and z axes very rapidly (Fig. 8) so that the lifetime of a given distortion, r, is much less than the lifetime of a given coordinated H20 molecule, THa0 (99,... 

In the limit of strong vibronic coupling, F4S = 0, c = 5 /3, s=, c2 - s2 =, and the dynamic Jahn-Teller effect thus renders nugatory the orbital contributions to the angular momentum, and reduces the splitting, A, by a factor of two. Note in addition that the c and s quantities used in the vibronic treatment do not correspond to those of the adiabatic case, although the expressions are formally similar, so that the static distortion, A, cannot accurately be calculated from the c and s values deduced from the and 4 data. 

To summarize, the dynamical Jahn-Teller effect is found to be more significant (about one order of magnitute larger) than the GP effect as far as the... 

These TR results demonstrate that the localized model of Ru(bpy) + is valid on the timescales of electronic motions and molecular vibrations. It is virtually certain that delocalization (via, for example, intramolecular electron transfer or dynamic Jahn-Teller effects) occurs on some longer timescale. 

Cotton, F. A., and M. D. Meyers Magnetic and spectral properties of the spin-free 3d -systems FeFj" and CoF Probable observation of dynamic Jahn. Teller effects. J. Am. Chem. Soc. 82, 5023 (1960). 

The Cupric, Cu2+ or Cu(II) State, 3d9 The most important and stable oxidation state for copper is divalent. There is a well-defined aqueous chemistry of the Cu2+ ion, which generates the familiar blue solution when complexed with water. A large number of copper coordination compounds exist and these have been studied extensively. A strong Jahn-Teller distortion is associated with the 3d9 electronic configuration of this ion. This implies that a regular tetrahedron or octahedron about the Cu2+ ion is never observed, except in the rare occurrence of a dynamic Jahn-Teller effect. The tetragonal distortion about an octahedron can lead to a square-planar coordination which is often observed in Cu(II) oxides. 

A very similar situation is presented by the dynamic Jahn-Teller effect, in which a trapped electron that has distorted its surroundings hops between two configurations with a frequency given by (6) for a proof see Sturge (1967). 

There is an interesting series of compounds, all of them containing the hexa-nilrocupratefll) ion ([CufNCyj4-). which exhibit the foil range of static and dynamic Jahn-Teller effects described above.30 n some members of the series, such as... 

Figure 69 Vibronic coupling for octahedral copper(II) (a) dynamic Jahn-Teller effect (alg and blg) (b) pseudo...

In connection with the Jahn-Teller effect the role of A may be well defined. It has been shown that if a dynamic Jahn-Teller effect is operative, very substantial quenching of orbital angular momentum may take place — the Ham effect. In the case of T ground terms, if the dynamic Jahn-Teller frequencies bear the right relationship to spin-orbit coupling and temperature, A may be reduced to values well below 0.5.113119... 

Fig. 3.6. Elongations along the three principal axes of the Cu-O bonds in the hexaaqua copper(II) complex due to dynamic Jahn-Teller effects occur randomly with a correlation time of about 5 x 10-12 s.

An interesting aspect of this problem is that posed by the Jahn-Teller effect in the benzene anion. These ions, together with the cations and anions of coronene (Bolton and Carrington, 1961c de Boer and Weissman, 1958), have spectra consisting of unusually broad lines which are very hard to saturate. Theoretical studies (McConnell, 1961 McConnell and McLachlan, 1961) suggest that the broadening is a result of spin-orbit interaction but the relaxation is linked to the dynamic Jahn-Teller effect. 

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