2-[2-(4-Methoxyphenyltelluro)ethyl]thiophene (L1) bis[2-(2-thienyl)ethyl] telluride (L2) and their metal complexes; crystal structure of trans-dichlorobis{2-(2-(4-methoxyphenyltelluro)ethyl)thiophene-Te}palladium(II) and {bis[2-(2-thienyl)ethyl] telluride

The reaction of ArTe− (Ar=4-MeOC6H4) and Te2− generated in situ by borohydride reduction of Ar2Te2 and Te, respectively, with 2-(2-thienyl)ethyl chloride has resulted in 2-[2-(4-methoxyphenyltelluro)ethyl]thiophene (L1) and bis[2-(2-thienyl)ethyl] telluride (L2), respectively. Their complexes [AgNO3(L1)] (1) [PdCl2(L1)2] (2) [PtCl2(L1)2] (3) [HgBr2(L1)]2 (4) [Ru(p-cymene)Cl2(L1)] (5) [Ru(p-cymene)Cl2(L2)] (6) and [PdCl2(L2)2] have been synthesized. The ligands and complexes exhibit characteristic 1H and 13C{1H} NMR spectra. Both the ligands coordinate only through Te in all the complexes. The single crystals of 2 and 6 are characterized by X-ray diffraction. Compound 2 has square planar geometry around Pd and trans arrangement of ligands. The Pd–Te bond distances 2.5951(7) and 2.5872(7) Å are longer than the values expected due to strong trans influence. The unique intermolecular secondary Te⋯Cl interaction (distance=3.450/3.449 Å) between neighbouring molecules has been observed in the crystal structure of 2. The distance between Pd atoms of two neighbouring molecules 3.2143(10) Å has also been found less than the sum of van der Waalʹs radii 3.26 Å. These secondary interactions in 2 result in the formation of a dimeric species, which remains intact even in the solution. Compound 6 is a half sandwich having three coordination sites occupied by two Cl atoms and the Te atom of L2 with Ru–Te bond distance of 2.6528(9) Å and Ru–Cl, 2.415(2)/2.422(2) Å.