Synthesis and structural studies of 1-naphthyl and mesityl ligand bearing organotellurium(II and IV) derivatives

Abstract

We report the synthesis and single crystal X-ray studies of air- and moisture-stable unsymmetrical organotellurium(II) and organotellurium(IV) derivatives bearing mesityl and 1-naphthyl ligands. The organotellurium(IV) derivatives, RR’TeCl₂ (1) and RR“TeCl₂ (2), [R = 2-(4,4′-NO₂C₆H₄CH = NC₆H₃-Me), R′ = 1-naphthyl, R″ = mesityl], were prepared by the treatment of RHgCl with R’TeCl₃ and R”TeCl₃ respectively in chloroform solvent at room temperature. The organotellurium(II) derivatives, RR’Te (3) and RR“Te (4) were prepared by reducing compounds 1 and 2 in dichloromethane:water solvent. Along with these we also developed compound R’(CH₃COCH₂)TeCl₂ (5) through the treatment of R’TeCl₃ with acetone at room temperature. All five compounds were characterized using ¹H NMR, ¹³C{¹H}-NMR, ¹²⁵Te{¹H}-NMR, IR, ES-MS and UV spectroscopic techniques and elemental analysis. Additionally, compounds 3, 4 and 5 were confirmed by single-crystal X-ray studies. The crystal packing diagram of 3 shows intermolecular CH∙∙∙O and CH∙∙∙Te interactions that are within the Σ rvdw (H,O) of 2.72 Å and (H,Te) of 3.28 Å for the two atoms, giving rise to 1D supramolecular motifs via self-assembly. The crystal packing of 3 also displays an interesting centrosymmetric dimeric unit via CH∙∙∙O interactions. This synthon is based on reciprocal CH···O H-bonding interactions of the nitro ligand bearing phenyl fragment. Based on Bent’s rule, we also conclude that the sharing of s-character in these molecules is greater through the mesityl ligand than the tolyl, 1-naphthyl and 4-anisyl organic fragments. The order of electronegativity of these organic fragments in these telluroethers will be mesityl < 4-tolyl < 1-naphthyl < 4-anisyl.