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The Jahn–Teller effect (JT effect or JTE) is an important mechanism of spontaneous symmetry breaking in molecular and solid-state systems which has far-reaching consequences in different fields, and is responsible for a variety of phenomena in spectroscopy, stereochemistry, crystal chemistry, molecular and solid-state physics, and materials science.
Second-order Jahn-Teller distortion provides a rigorous and first-principles approach to the distortion problem. The interactions between the HOMOs and LUMOs to afford a new set of molecular orbitals is an example of second-order Jahn-Teller distortion.
In their early 1957 paper on what is now called pseudo Jahn–Teller effect (PJTE), Öpik and Pryce [2] showed that a small splitting of the degenerate electronic term does not necessarily remove the instability and distortion of a polyatomic system induced by the Jahn–Teller effect (JTE), provided that the splitting is sufficiently small (the two split states remain "pseudo degenerate ...
Another example is [Co(H 2 O) 6] 2+. [14] Note that the ligand is the same as the last example. Here the cobalt ion has the oxidation state of +2, and it is a d 7 ion. From the high-spin (left) side of the d 7 Tanabe–Sugano diagram, the ground state is 4 T 1 (F), and the spin multiplicity is a quartet.
Complexes such as this are called "low spin". For example, NO 2 − is a strong-field ligand and produces a large Δ. The octahedral ion [Fe(NO 2) 6] 3−, which has 5 d-electrons, would have the octahedral splitting diagram shown at right with all five electrons in the t 2g level. This low spin state therefore does not follow Hund's rule.
Known for his "life-long years of experience in theoretical chemistry" [1] working on the electronic structure and properties of coordination compounds, Isaac B. Bersuker is “one of the most widely recognized authorities” [2] in the theory of the Jahn–Teller effect (JTE) and the pseudo-Jahn–Teller effect (PJTE).
The Renner-Teller effect is a phenomenon in molecular spectroscopy where a pair of electronic states that become degenerate at linearity are coupled by rovibrational motion. [ 1 ] The Renner-Teller effect is observed in the spectra of molecules that have electronic states that allow vibration through a linear configuration.
the Jahn-Teller effect is a pretty advanced topic in chemistry and a reader would really benefit from some groundwork, octahedral complex would be preferable over octahedral complex. See also the AXE method, most molecular geometries are still missing. V8rik 20:07, 12 July 2005 (UTC)