Select the Incorrect statement from the following for [Ti(H2O)6]Cl3.

The correct answer is Option (3) → On strong heating colour of [Ti(H₂O)₆]Cl₃ changes to yellow.

The colour of most transition metal complexes comes from a d–d transition. The ligands split the d orbitals; in an octahedral field they split into a lower t_2g set and a higher e_g set, separated by Δ_o. An electron absorbs visible light of energy Δ_o and moves from t_2g to e_g; the complex shows the complementary colour.

For \( \ce{[Ti(H2O)6]^{3+}} \), the oxidation state of Ti (\( \ce{H2O} \) is neutral):

    \( \displaystyle x+6(0)=+3 \)

    \( \displaystyle x=+3 \)

Ti (Z = 22) is [Ar]3d²4s²; losing the two 4s electrons and one 3d electron gives Ti³⁺: 3d¹, i.e. t_2g¹e_g⁰. The complex absorbs blue-green light (about 498 nm) and looks violet.

On strong heating the water ligands are lost, so the compound becomes colourless, not yellow.

• Option (1) It is violet in colour. — A correct statement for [Ti(H₂O)₆]Cl₃. It absorbs in the blue-green region, so it appears violet.

• Option (2) Colour of this complex is due to d-d transition of the electron. — A correct statement for [Ti(H₂O)₆]Cl₃. The single 3d electron is promoted from t_2g to e_g.

• Option (3) On strong heating colour of [Ti(H₂O)₆]Cl₃ changes to yellow. — The incorrect statement. Without the water ligands there is no crystal field splitting, so it becomes colourless.

• Option (4) Metal ion ground state electronic configuration is t_2g¹e_g⁰. — A correct statement for [Ti(H₂O)₆]Cl₃. \( \ce{Ti^{3+}} \) (3d¹) places its one electron in the lower-energy t_2g set.

NCERT (2026-27 edition):
Colour in Coordination Compounds – …