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Orgel diagrams are restricted to only show weak field (i.e. high spin) cases, and offer no information about strong field (low spin) cases. Because Orgel diagrams are qualitative, no energy calculations can be performed from these diagrams; also, Orgel diagrams only show the symmetry states of the highest spin multiplicity instead of all ...
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.
In this case, Orgel diagrams are restricted to only high spin complexes. [8] Tanabe–Sugano diagrams do not have this restriction, and can be applied to situations when 10Dq is significantly greater than electron repulsion. Thus, Tanabe–Sugano diagrams are utilized in determining electron placements for high spin and low spin metal complexes.
In an octahedral complex, the molecular orbitals created by coordination can be seen as resulting from the donation of two electrons by each of six σ-donor ligands to the d-orbitals on the metal. In octahedral complexes, ligands approach along the x -, y - and z -axes, so their σ-symmetry orbitals form bonding and anti-bonding combinations ...
Complexes which are d 8 high-spin are usually octahedral (or tetrahedral) while low-spin d 8 complexes are generally 16-electron square planar complexes. For first row transition metal complexes such as Ni 2+ and Cu + also form five-coordinate 18-electron species which vary from square pyramidal to trigonal bipyramidal .
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. High Spin [FeBr 6] 3− crystal field diagram
Crystal field diagram for octahedral low-spin d 5 Crystal field diagram for octahedral high-spin d 5. According to crystal field theory, the d orbitals of a transition metal ion in an octahedal complex are split into two groups in a crystal field. If the splitting is large enough to overcome the energy needed to place electrons in the same ...
An important class of complexes that violate the 18e rule are the 16-electron complexes with metal d 8 configurations. All high-spin d 8 metal ions are octahedral (or tetrahedral), but the low-spin d 8 metal ions are all square planar. Important examples of square-planar low-spin d 8 metal Ions are Rh(I), Ir(I), Ni(II), Pd(II), and Pt(II). At ...