5,11,17,23-tetraiodo-25,26,27,28-tetrapropoxythiacalix[4]arene exhibited I⋯I interactions which are ca. 2% shorter than the sum of their respective van der Waals atomic radii. 5,11,17,23-tetraiodo-25,26,27,28-tetrabutoxythiacalix[4]arene were identified to have S⋯I interactions that are ca. 4.5% shorter than the sum of their respective van der Waals atomic radii. We have elucidated both interactions by computational approaches.