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

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 C[sbnd]H∙∙∙O and C[sbnd]H∙∙∙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 C[sbnd]H∙∙∙O interactions. This synthon is based on reciprocal C[sbnd]H···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.