Аннотация:Crystal and electronic structures of a newly synthesized thiazolium pentaiodide, C3H4NS(I5), were examined in detail. Thetitle pentaiodide crystallizes in the monoclinic space group P21/m with the unit cell volume of 1289.27(6) Å3. Its crystal structurefeatures branched pentaiodide chains composed of alternating I3− and I2building units, whereas the chains are furtherlinked into a 3D array by thiazolium cations with the help of (N)H⋅⋅⋅I and S⋅⋅⋅I bonds. The electronic structure and bondingassessed by DFT calculations show that covalent interactions within the I2and I3− units are supplemented by non-covalent (N)H⋅⋅⋅I and S⋅⋅⋅I interactions, which were revealed by the electron localization function and reduced density gradient analyses.