N-{2-(4-Methoxyphenyltelluro)ethyl}morpholine (L1) and bis{2-(N-morpholino)ethyl}telluride (L2): synthesis and complexation with palladium(II) and mercury(II). Crystal structures of trans-[PdCl2(L1)2] and trans-[PdCl2(L2)2]

The reactions of 4-(2-chloroethyl)morpholine hydrochloride with ArTe− and Te2−, generated in situ (under N2 atmosphere) have resulted in N-{2-(4-methoxyphenyltelluro)ethyl}morpholine (L1) and bis{2-(N-morpholino)ethyl}telluride (L2), respectively, which are first tellurated derivatives of morpholine. 1H- and 13C{1H}-NMR spectra of L1 are as expected but HETCOR experiments are used to assign the overlapping signals of CH2Te and CH2N in 1H-NMR spectrum of L2. The complexes of stoichiometries [PdCl2(L1/L2)2] (1/3) and [HgBr2(L1/L2)]2 (2/4) are synthesized. The NMR (1H and 13C{1H}) spectra of all the four complexes have CH2Te and ArCTe signals deshielded with respect to those of free L1/L2, indicating that the two ligands coordinate through Te only. The trans Pd-complexes 1 and 3 are characterized structurally and their PdTe bond lengths (average) are 2.596 and 2.600 Å, respectively. The Pd-Cl bonds in 1 are marginally shorter (average 2.312 Å) in comparison to those of 3 (average 2.325 Å). The geometry of palladium is square planar. The TeC(aryl) is shorter than TeC(alkyl). The dimeric mercury complexes 2 and 4 appear to be formed through the formation two bromo bridges between Hg atoms.