Chemistry · Ch 5 — Coordination Chemistry
Crystal Field Splitting in Tetrahedral Complexes
Crystal Field Splitting in Tetrahedral Complexes
In a tetrahedral field, the four ligands can be visualised approaching along four alternate corners of a cube that has the metal ion at its centre -- i.e. along the cube's leading body diagonals. In this geometry none of the five d orbitals point directly at a ligand, but the t2 orbitals (dxy, dyz, dzx) lie closer to the ligand-approach directions than the e orbitals (dx²-y², dz²) do. Consequently the splitting pattern inverts relative to the octahedral case: the t2 set rises by 2/5 Δt while the e set falls by 3/5 Δt. Because none of the orbitals point directly at any ligand in a tetrahedral field (unlike the axial eg orbitals in an octahedral field), the overall splitting is both inverted in order and smaller in magnitude; the two splitting energies are related by Δt = …
What this figure shows. A cube with the central metal atom placed at its centre (the origin of the coordinate axes X, Y, Y', X', Z, Z'), and four ligands L1-L4 approaching along four alternate corners of the cube -- the leading diagonal directions -- rather than along the face-centre axes used in the …
What this figure shows. The same cube-and-metal-centre setup as Figure 5.11, now with the five d orbital lobes superimposed at the centre (dxy, dxz, dyz, dz², dx²-y²) and the four ligands L1-L4 approaching along the cube's leading diagonals -- illustrating that the t2 orbitals (dxy, dyz, dxz) lie closer to these diagonal approach directions than the e orbitals (dz² …
What this figure shows. An energy-level diagram analogous to Figure 5.10 but for the tetrahedral case: starting from the five degenerate free-ion d orbitals, then the raised, still-degenerate average energy in a spherical field, then the final tetrahedral split -- here the t2 set (dxy, dyz, dxz) is raised by 2/5 Δt ABOVE the average while the e set (dx²-y², dz²) is lowered by 3/5 Δt below it, the reverse ordering from the octahedral case, with the overall gap Δt shown small …