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)ethyll telluride} dichloro(p-cymene)ruthenium(II)

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 (L-1) and bis[2-(2-thienyl)ethyl] telluride (L-2), respectively. Their complexes [AgNO3(L-1)] (1) [PdCl2(L-1)(2)] (2) [PtCl2(L-1)(2)] (3) [HgBr2(L-1)](2) (4) [Ru(p-cymene)Cl-2(L-1)] (5) [Ru(p-cymene)Cl-2(L-2)] (6) and [PdCl2(L-2)(2)] have been synthesized. The ligands and complexes exhibit characteristic H-1 and C-13{H-1} 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) Angstrom are longer than the values expected due to strong trans influence. The unique intermolecular secondary Te...Cl interaction (distance = 3.450/3.449 Angstrom) between neighbouring molecules has been observed in the crystal structure of 2. The distance between Pd atoms of two neighbouring molecules 3.2143(10) Angstrom has also been found less than the sum of van der Waal's radii 3.26 Angstrom. 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 L-2 with Ru-Te bond distance of 2.6528(9) Angstrom and Ru-Cl, 2.415(2)/2.422(2) Angstrom. (C) 2004 Elsevier B.V. All rights reserved.