This work is devoted to the discussion of structural changes in crystalline iodine under low temperature studied from experimental and theoretic points of view. Experimental Raman spectra in the temperature range 5-300 K demonstrated unusual behavior of stretching vibration at similar to 180 cm(-1) with temperature. The data allowed obtaining of omega(T) functions for both external translational and internal stretching modes of I-2. It was found that omega(T) trends significantly differ in comparison to typical van der Waals crystal alpha-S-8. The observed anomalies are explained from a theoretic point of view because of the strengthening of intralayer halogen bonding between I-2 molecules.