Octahedral , vibrational

Fie- 3.23. The emission speetrum of Ba2ZnWOft U " at 4.2 K. The zero-phonon line is indicated by O, the vibronic lines are indicated by the octahedral vibrational modes with which the coupling with the electronic transition takes place... 

For a spherical rotor belonging to the octahedral Of, point group, Table A.43 in Appendix A, in conjunction with the vibrational selection rules of Equation (6.56), show that the only allowed transitions are... 

All the forbidden electronic transitions of regular octahedral transition metal complexes, mentioned in Section 7.3.1.4, are induced by non-totally symmetric vibrations. 

Vibrational spectra and F nmr studies on all three cations XFe+ and the 1 Mdssbauer spectmm of [lF6][AsF6] establish octahedral (Oh) symmetry as expected for species isoelectronic with SFfi, SeFfi and TeFg respectively. 

Now consider a molecular stretching vibration that alternately elongates and compresses axial (parallel to z, let s say) and equatorial bonds as outlined in Fig. 7-3. Imagine an extreme vibration of this kind that eventually distorts an octahedral molecule so as to gradually remove two trans ligands (again, let this direction be... 

Diffraction patterns and FTIR spectra of skeletal vibrations of the ZSM-5 and ferrierite zeolites indicated high crystallinity of the analyzed samples. The strong band with a chemical shift of about 55 ppm in the 27Al MAS NMR spectra of hydrated zeolites indicated the presence of more than 97 % Al in the framework in tetrahedral coordination the very low intensity of the peak at 0 ppm indicated less than 3 % rel. of Al in octahedral coordination. 

The above results mainly apply to the Longuet-Higgins E x e problem, but this historical survey would be incomplete without reference to early work on the much more challenging problems posed by threefold or higher electronic degeneracies in molecules with tetrahedral or octahedral symmetry [3]. For example, tetrahedral species, with electronic symmetry T or T2, have at least five Jahn-Teller active vibrations belonging to the representations E and T with individual coordinates (Qa,Qb) and (Qx. Qx. Q ) say. The linear terms in the nine Hamiltonian matrix elements were shown in 1957 [3] to be... 

Swanson, B. I. and S. K. Satija. 1977. Molecular vibrations and reaction pathways. Minimum energy coordinates and compliance constants for some tetrahedral and octahedral complexes. J. Am. Chem. Soc. 99 987-991. 

Flint end Matthews (148) have used the AOM in a qualitative way in the analysis of the vibronic structure in the 4A2g -+ 2Eg absorption and 2Eg -> 4A2g luminiscence of octahedral Cr(III) chromophores. It can be predicted that ligand vibrational modes... 

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