First ICN adduct with a selenium donor (R=Se): Is it an ionic [RseCN]+I– or a “T-shaped” R(I)SeCN hypervalent compound?

The reaction between 1,3-dimethyl-4-imidazoline-2-selone (2) and ICN gave the adduct 2·ICN, whose crystal structure features dimers made up of two [2·CN]+ and two I− which strongly interact. Hybrid DFT calculations on the adduct 2·ICN, on the cation [2·CN]+, and on the dimer (2·ICN)2 account for a partially hypervalent selenium atom in 2·ICN and for the observed structural features