l₂ is violet in the solid as well as in the gas phase. However, in acetone or ethanol, it turns brown. Choose the correct statement(s) for this color change:

(a) Dissociation of 12 in atomic state

(b) Interaction of low-lying σ*-orbital of iodine with lone pair of O (solvent)

(c) Formation of a charge-transfer complex

Concept:

Charge Transfer complex:

• A charge transfer complex is an association of two or more molecules. The complex results in an electrostatic attraction and undergoes an electronic transition into an excited electronic state.  

Explanation:

• Iodine is a chemical element with atomic number 53. Iodine belongs to group 17 in the periodic table.
• The violet color of l2 gas is due to the absorption of visible light by l2 gas resulting in an electronic transition between the highest and lowest molecular orbitals. For this electronic transition, l2 absorbs red light from visible light and emits a violet color.
• The color of the l2 solution depends upon the nature of the solvent. Iodine gas is highly soluble in non-polar solvents like hexane and carbon tetrachloride.
• When l2 gas is dissolved in polar solvents like acetone or ethanol, this results in a charge transfer complex. The interaction of low-lying σ*-orbital of iodine with lone pair of O (solvent) results in the brown color of l2 gas.

​Conclusion:

• Hence, the correct statement(s) for this color change (b) and (c) only