Search results
Results From The WOW.Com Content Network
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.
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.
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.
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 ...
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 picture below is shown the splitting of the d subshell in low-spin square-planar complexes.
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 .
Due to a smaller crystal field splitting energy, the homoleptic halide complexes of the first transition series are all high spin. Only [CrCl 6 ] 3− is exchange inert. Homoleptic metal halide complexes are known with several stoichiometries, but the main ones are the hexahalometallates and the tetrahalometallates.
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 ...