ASYMMETRIC DIORGANOTELLURIDES CONTAINING SUBSTITUTED PYRIDYL GROUPS -SYNTHESIS AND LIGATION WITH PALLADIUM(II) AND PLATINUM(II) - CRYSTAL-STRUCTURE OF 6H4TECH(2)CH(2)-2-(C5H4N))CL-2]CENTER-DOT-2CHCL(3)

A (N,Te,N) ligand 2-(2-pyridoethyletelluro)ethylpyridine (1) has been synthesized by reacting in situ generated Na2Te with 2-(2-chloroethyl) pyridine. The Pd-II and Pt-II complexes of stoichiometry [MCl . 1]Cl h ave been studied. The deshielding of ortho protons of pyridine and CH2 Te signal (up to 0.5 ppm) indicate that 1 ligates in a tridentate mode . The red shift (20-25 cm(-1)) in nu(Te-C(alkyl)) supports the involve ment of Te in coordination. Molecular weights and Lambda(M) values of these complexes support their ionic nature (1:1 electrolyte). The reac tions of 2-(chloromethyl)pyridine and 2,6-bis(chloromethyl)pyridine wi th ArTeNa (Ar = 4-MeQC(6)H(4)) could not produce (N,Te) and (Te,N,Te) ligands comprising pyridyl groups. The CHCl3 present as a solvent in t hese reactions reacted with ArTeNa resulting in (ArTe)(2)CH2. To under stand the behaviour of Te donor site vis-a-vis pyridyl group the singl e crystal structure of Pd{4-MeC(6)H(4)TeCH(2)CH(2)-2-(C5H4N)}Cl-2 . 2C HCl(3) was solved. An endo, puckered chelate ring is formed by (N,Te) ligand. The trans influence of the pyridyl group appears to be lower o r comparable to that of tellurium. Copyright (C) 1996 Elsevier Science Ltd