2-62-(4-Methoxyphenyltelluro)ethyl9thiophene (L1) bis62-(2-thienyl)ethyl9 telluride (L2) and their metal complexes; crystal structure of trans-dichlorobis$lcurlb;2-(2-(4-methoxyphenyltelluro)ethyl)thiophene-Te$rcurlb;palladium(II) and $lcurlb;bis62-(2-thienyl)ethyl9 telluride$rcurlb;dichloro(p-cymene)ruthenium(II)

Abstract

2-[2-(4-methoxyphenyltelluro)ethyl]thiophene ( L 1 ), bis[2-(2-thienyl)ethyl] telluride ( L 2 ) and their complexes with AG(I), Hg(II) Pd(II), Pt(II) and Ru(II) have been synthesized and characterized by 1 H and 13 C{ 1 H} NMR spectra. The two ligands coordinate only through Te. Single crystal structure of [PdCl 2 ( L 1 ) 2 ] ( 2 ) and [Ru( p -cymene)Cl 2 ( L 2 )] ( 6 ) are solved. The Pd in 2 has square planar geometry and trans arrangement of ligands (Pd–Te=2.5951(7) and 2.5872(7) Å). Unique intermolecular secondary Te⋯Cl interaction (distance=3.450/3.449 Å) between neighbouring molecules in 2 results in the formation of a dimer (Pd–Pd=3.2143(10) Å). In half sandwich compound 6 three coordination sites are occupied by two Cl atoms and Te atom of L 2 (Ru–Te=of 2.6528(9) Å; Ru–Cl=2.415(2)/2.422(2) Å). The reaction of ArTe − (Ar=4-MeOC 6 H 4 ) and Te 2− generated in situ by borohydride reduction of Ar 2 Te 2 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 [AgNO 3 ( L 1 )] ( 1 ) [PdCl 2 ( L 1 ) 2 ] ( 2 ) [PtCl 2 ( L 1 ) 2 ] ( 3 ) [HgBr 2 ( L 1 )] 2 ( 4 ) [Ru( p -cymene)Cl 2 ( L 1 )] ( 5 ) [Ru( p -cymene)Cl 2 ( L 2 )] ( 6 ) and [PdCl 2 ( L 2 ) 2 ] have been synthesized. The ligands and complexes exhibit characteristic 1 H and 13 C{ 1 H} 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 Waal's 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 L 2 with Ru–Te bond distance of 2.6528(9) Å and Ru–Cl, 2.415(2)/2.422(2) Å.