Structural characterization of rare intramolecularly (1,4-Te⋯N) bonded diorganotellurides and their monomeric complexes with mercury(II) halides: Metal assisted C–H⋯X (Hg) interactions leading to supramolecular architecture

Monomeric tellurides 4-RC6H4(SB)Te [SB = 2-(4,4′-NO2C6H4CHdouble bond; length as m-dashNC6H3–Me); R = H, 1a; Me, 1b; OMe, 1c], which incidentally represent the first example of a telluride with 1,4-Te⋯N intramolecular interaction, have been prepared and characterized by solution and solid-state 125Te NMR, 13C NMR and X-ray crystallography. Interplay of weak C–H⋯O and C–H⋯π interactions in the crystal lattice of 1b and 1c are responsible for the formation of supramolecular motifs. These tellurides undergo expected oxidative addition reactions with halogens and interhalogens and also interact coordinatively with mercury(II) halides to give 1:2 complexes, HgX2[4-RC6H4(SB)Te]2 (X = Cl, R = H, 2a; Me, 2b; OMe, 2c and X = Br, R = H, 3a; Me, 3b; and OMe, 3c) with no sign of Te–C bond cleavage, as has been reported for some 1,5-Te⋯N(O) intramolecularly bonded tellurides. The complexes 2a and 3c are the first structurally characterized monomeric 1:2 adducts of mercury(II) halides with Te ligands. The 1,4-Te⋯N intramolecular interactions in the solid-state are retained in the complexes highlighting simultaneously the Lewis acid and base character of the Te(II) atom. Packing of molecules in the crystal lattice of 2a and 3c reveals that non-covalent C–H⋯Cl/Br interactions involving metal-bound halogen atoms possess significant directionality and in combination with coordinative covalent interactions may be of potential use in creating inorganic supramolecular synthons.