Oxidation state of Ti in TiCl3 is +3 Electronic configuration is [Ar] 3d14s0. In absence of ligands, no splitting occurs, in d-orbitals of Ti3+ ions. So, no transitions are possible. Hence, TiCl3 is colourless. Oxidation state of Ti in [Ti2H2O6]Cl3 is +3. In presence of a ligand, splitting in d-orbitals occur. Hence, [Ti(H2O)6]Cl3 is coloured. TiCl3(X)→ colourless [Ti(H2O)6]Cl3(Y)→ coloured