Asymmetric diorganotellurides containing substituted pyridyl groups - Synthesis and ligation with palladium(II) and platinum(II). Crystal structure of [Pd{4-MeC6H4TeCH(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 have been studied. The deshielding of ortho protons of pyridine and CH2Te 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 involvement of Te in coordination. Molecular weights and Lambda(M) values of these complexes support their ionic nature (1:1 electrolyte). The reactions of 2-(chloromethyl)pyridine and 2,6-bis(chloromethyl)pyridine with 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 these reactions reacted with ArTeNa resulting in (ArTe)(2)CH2. To understand the behaviour of Te donor site vis-a-vis pyridyl group the single crystal structure of Pd{4-MeC(6)H(4)TeCH(2)CH(2)-2-(C5H4N)}Cl-2 . 2CHCl(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 or comparable to that of tellurium. Copyright (C) 1996 Elsevier Science Ltd