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Spin crossover is sometimes referred to as spin transition or spin equilibrium behavior. The change in spin state usually involves interchange of low spin (LS) and high spin (HS) configuration. [2] Spin crossover is commonly observed with first row transition metal complexes with a d 4 through d 7 electron configuration in an octahedral ligand ...
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 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 ...
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.
A consequence of the much smaller size of Δ T results in (almost) all tetrahedral complexes being high spin and therefore the change in the ground state term seen on the X-axis for octahedral d 4-d 7 diagrams is not required for interpreting spectra of tetrahedral complexes.
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.
Inverse spinel structures have a different cation distribution in that all of the A cations and half of the B cations occupy octahedral sites, while the other half of the B cations occupy tetrahedral sites. An example of an inverse spinel is Fe 3 O 4, if the Fe 2+ (A 2+) ions are d 6 high-spin and the Fe 3+ (B 3+) ions are d 5 high-spin.
The spin transition is an example of transition between two electronic states in molecular chemistry. The ability of an electron to transit from a stable to another stable (or metastable ) electronic state in a reversible and detectable fashion, makes these molecular systems appealing in the field of molecular electronics .