Based on the crystal field theory, why does the color of thecobalt complex, (cob

Question

Based on the crystal field theory, why does the color of thecobalt complex, (cobalt acetonate) (Co(acac)3) change when it is oxidized from Co 2+ to Co3+? *I don't really understand CFT, and I really would appreciatesomeone explaining why this happens. Thanks! Based on the crystal field theory, why does the color of thecobalt complex, (cobalt acetonate) (Co(acac)3) change when it is oxidized from Co 2+ to Co3+? *I don't really understand CFT, and I really would appreciatesomeone explaining why this happens. Thanks!

Explanation / Answer

The d-orbitals of a free transition metal atom or ionare degenerate (all have the same energy.) However, when transitionmetals form coordination complexes, the d-orbitals of the metalinteract with the electron cloud of the ligands in such a mannerthat the d-orbitals become non-degenerate (not all having the sameenergy.) The way in which the orbitals are split into differentenergy levels is dependent on the geometry of the complex. Crystalfield theory can be used to predict the energies of the differentd-orbitals, and how the d-electrons of a transition metal aredistributed among them. When the d-level is not completely filled,it is possible to promote and electron from a lower energyd-orbital to a higher energy d-orbital by absorption of a photon ofelectromagnetic radiation having an appropriate energy.Electromagnetic radiations in the visible region of the spectrumoften possess the appropriate energy for suchtransitions.
In case of Co+3 There is a possibility of electron transfer fromt2g orbital to eg orbital. This casues to thecolor to complex. There is a possibility of electron transfer fromt2g orbital to eg orbital. This casues to thecolor to complex.

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