Consider the three ligand field spectra corresponding to octahedral complexes A, B, and C, all formed from the same metal ion.

From the following list, Ti3, Ni2, Pt4, Cu2, to which metal ions could the spectra correspond and to which would it be very unlikely

Ni^2 + is most likely

Ti^3 + is very unlikely

Explanation:

The Crystal Field Stabilization Energy almost always favors octahedral over tetrahedral in very many cases, but the degree of this favorability varies with the electronic configuration. In other words, for d1 there is only a small gap between the octahedral and tetrahedral lines, whereas at d3 and d8 is a very big gap. However, for d0, d5 high spin and d10, there is no crystal field stabilization energy difference between octahedral and tetrahedral. The ordering of favorability of octahedral over tetrahedral is:

d3, d8 > d4, d9> d2, d7 > d1, d6 > d0, d5, d10. This explains the answer choices above.

Ti^3 + being a d1 specie is least likely to exist in octahedral shape while Ni2 + a d8 specie is more likely to exist in octahedral shape.