Jahn-Teller splittings

The splitting of the asymmetric peak is ascribed to a Jahn-Teller splitting of the excited state which latter involves the open e configuration e ... 

Figure 1. Potential energy diagram for cyclopropane in its ground state ( A/) and the two lowest states of its radical cation ( A, and 82). The vertical transition yields two bands (Jahn-Teller split) in the photoelectron spectrum.

Robert Plane I would like to comment on the photochemistry of these complexes, particularly the chromium which I think are well chosen for at least two of Dr. Gray s reasons. First, in the case of chromium, unlike cobalt, the charge transfer band is well separated, so that one can study the d-d transitions, at least in certain systems where one has six ligands all alike, and there is no Jahn-Teller splitting, and one has a fairly good idea as to the assignment of bands. 

Fig. 8.6. Energy levels showing the Jahn-Teller splitting in octahedrally coordinated transition metal cations (a) d" (Mn +), (b) d (Cu +). The energy levels are shown (i) in a spherical field, (ii) in a regular octahedral field, and (iii) in a tetragonally distorted octahedral field.

E. W. Schlag Yes, we do see splitting of the ion states. In particular, we see the Jahn-Teller splitting for the first time for benzene ions and in great detail. 

Figure 21 Qualitative representation of the origin of the Jahn-Teller splitting of orbitally degenerate ground terms. On the right the net lowering of energy is jAJT( E)...

Formally octahedral VL6 complexes give a band rather like that of TiL6 ones, but the splitting is rather larger (2000—6000 cm-1).38 Tetrahedral VC14 gives a very broad band (e 100) at —9000 cm"1, which has a structure which may arise from Jahn-Teller splitting.140 The band is of course 2T2(t2)<-2E(e), with Dq = —900 cm-1. 

ENERGY SURFACES FOR DYNAMIC JAHN-TELLER SPLITTING IN THE A — T TRANSITIONS IN TETRAHEORAL Co(ll)... 

Jones, G. D. (1967) Jahn-Teller splittings in the optical absorption spectra of divalent iron compounds. Phys. Rev., 155,259-61. 

FIGURE 3. (a) Comparison of the He(I) PE spectra of the >3d-symmetric molecules ethane and disilane, which exhibit Jahn/Teller splitting (J/T) of their M (e) states with dominant contributions ( ) to positive hole delocalization, based on their quantitative radical cation state assignment (see text), (b) United Atom correlation for the isoelectronic 18-electron species from Ar to SiFLj including the iso(valence)electronic 10-electron molecule CH4 with average atomic ionization energies... 

Apart from spectroscopic constants, other observable spectroscopic features may be studied by consideration of calculated potential-energy surfaces. Notable in this respect is the understanding of observed Jahn-Teller splittings, a good example being the methane ion, CH4+.ia... 

Fig. 47. Normal vibrational modes Qi and Qi compatible with Jahn-Teller splitting of the degenerate ground state of an octahedral-site 3d4 and 3d cation, (a) Definition of modes for a free ion complex. (See following pages for Figs. 47(b) and 47(c).)...

The electronic spectrum of RhF6 has not been reported, but ligand field calculations have been used to predict its spectrum.1279 The IR spectrum of RhF6 has been reported,1280 and it is consistent with the expected Oh symmetry. Like IrF6, the rhodium hexafluoride does not show the Jahn-Teller splittings of the Eg mode observed for the analogous Tc, Re and Os hexafluorides. 

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