Reaction of imidazoline-2-selone derivatives with mesityltellurenyl iodide: a unique example of a 3c-4e Se→Te←Se three-body system embedding a tellurenyl cation

The reactions of 1,1′-bis(3-methyl-4-imidazolin-2-selone)methane ( L1 ) and 1,2-bis(3-methyl-4-imidazolin-2-selone)ethane ( L2 ) with mesityltellurenyl iodide (MesTeI) [Mes = 2,4,6-Me 3 C 6 H 2 ] yielded the neutral [ L1 ·2MesTeI]·2CH 2 Cl 2 and the ionic [ L2 ·MesTe] 2 (MesTeI 2 ) 2 compounds, respectively, which were characterized by X-ray diffraction analysis. DFT (mPW1PW//LANL08d/def2-SVP) and NBO calculations, supported by structural and FT-Raman measurements, show that the latter compound represents the first example of an authentic mesityltellurenyl cation, [MesTe] + , stabilized within a [MesTe(B) 2 ] + (B = Lewis base) charge transfer adduct featuring a 3c-4e Se→Te←Se three-body system.