Doubly-bridged PNP-lariat ethers and their complexes with silver( i ) ions in methanol solution

We report the preparation of four new double-bridged PNP-lariat ether derivatives L1-L4 synthesized from precursor 1 by the subsequent substitution of chlorine atoms. The process consists of two steps. In the first one two reactive chlorine atoms of the-PCl2 exocyclic moiety are substituted with respective nucleophiles: 2,2'-thiodiethanethiol 2 and 2,2'-oxydiethanethiol 3. In the second step the other chlorine atoms are substituted by aziridynyl 6 and pyrrolidinyl 7 groups, respectively. Their structures were established by MS, H-1 NMR, P-31 NMR, C-13 NMR spectroscopy. Furthermore, this work includes the investigation of complexation of silver(I) ions with the new ligands L1-L4 in methanol solution. The formation of the novel tetra-nuclear silver(I) complexes were observed. Stability constants were determined using a simple potentiometric titration. H-1 NMR, P-31 NMR, C-13 NMR spectra were recorded to investigate how the complexation of silver(I) ions by the investigated macrocyclic ligands occurs.