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In molecular physics, crystal field theory (CFT) describes the breaking of degeneracies of electron orbital states, ... In a tetrahedral crystal field splitting, ...
Low-spin [Fe(NO 2) 6] 3− crystal field diagram. The Δ splitting of the d orbitals plays an important role in the electron spin state of a coordination complex. Three factors affect Δ: the period (row in periodic table) of the metal ion, the charge of the metal ion, and the field strength of the complex's ligands as described by the spectrochemical series.
This rationale can explain anomalies in the spinel structures that crystal-field theory cannot, such as the marked preference of Al 3+ cations for octahedral sites or of Zn 2+ for tetrahedral sites, which crystal field theory would predict neither has a site preference.
Other common coordination geometries are tetrahedral and square planar. Crystal field theory may be used to explain the relative stabilities of transition metal compounds of different coordination geometry, as well as the presence or absence of paramagnetism, whereas VSEPR may be used for complexes of main group element to predict geometry.
John Stanley Griffith and Leslie Orgel [6] championed ligand field theory as a more accurate description of such complexes, although the theory originated in the 1930s with the work on magnetism by John Hasbrouck Van Vleck. Griffith and Orgel used the electrostatic principles established in crystal field theory to describe transition metal ions ...
The left depicts the relative energies of the d 7 ion states as functions of crystal field strength (Dq), showing an intersection of the 4 T 1 and the 2 E states near Dq/B ~ 2.1. Subtracting the ground state energy produces the standard Tanabe–Sugano diagram shown on the right.
Ligand field scheme summarizing σ-bonding in the octahedral complex [Ti(H 2 O) 6] 3+.. According to Ligand Field Theory, the ns orbital is involved in bonding to the ligands and forms a strongly bonding orbital which has predominantly ligand character and the correspondingly strong anti-bonding orbital which is unfilled and usually well above the lowest unoccupied molecular orbital (LUMO).
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.