Presentation on theme: "Colour and the d block. UV / Vis frequencies are have photons with energies of the sort of values needed to promote electrons from their ground state."— Presentation transcript:
UV / Vis frequencies are have photons with energies of the sort of values needed to promote electrons from their ground state energy level to a higher level. A typical substance will require UV photons so does not absorb Visible light. Most substances are colourless.
d – block metal complexes These have unusually close energy levels due to the splitting of the 3d orbitals in a non spherical environment.
But in an octahedral complex two of the orbitals will be closer to ligands than the other three. But ligands usually have a negative charge …..so electrons in the d orbitals are repelled. They have a higher energy
3d orbitals in complex Energy Further from ligands Closer to ligands
d electrons will tend to go preferentially into the lower energy orbitals further from the ligands. Ti has the electron configuration [Ar] 3d 2 4s 2 So Ti 3+ has the electron configuration [Ar] 3d 1