Synthesis and characterization of sterically congested mesityltris(imidazolium) salts and the corresponding highly crystalline tris-selone derivatives

The tandem synthesis of 1,1′,1″-[mesityltris(methylene)tris(3-R-1H-imidazolium)] bromides (3a–f; R=methyl, isopropyl, vinyl, allyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl) and corresponding tris-selones 4a–f starting from tris(bromomethyl)mesitylene was investigated. The compounds were characterized by ¹H, ¹³C, DEPT-135, HSQC, and HMBC NMR spectroscopy; IR spectroscopy; and elemental analysis. The unprecedented crystalline structures of the sterically hindered and synthetically challenging tris-selones possessing different geometrical orientations (with the exception of 4 f) were further corroborated by single-crystal X-ray diffraction analysis. Comparative UV/Vis analysis of 4a–f was also demonstrated.