In [Ti(H2O)6]3+, oxidation state of Titanium is +3.
Thus, electronic configuration:
Ti+3:3d1⇒t2g1,0,0,eg0,0
We know CFSE =[−0.4nt2g+0.6neg]Δo ( Δo=Octahedralsplittingenergy)
Δo=0.4×6×102396×103=4×10−19J
Using planck's equation and fact that octahedral splitting energy per complex is:
⇒Δo=λhc=4×10−19J
⇒λ=4×10−196.4×10−34×3×108=4.8×10−7m
⇒λ=480×10−9m
∴λ=480nm