LAUSR

A comparative investigation of the coordination behaviour of a 19-membered NO2S2-macrocycle (L1) and a 20-membered NO2S3-macrocycle (L2) is reported. On silver(i) complexation, L1 yields a discrete endocyclic mononuclear complex, whereas L2 affords a one-dimensional coordination polymer in which the endo-coordinated macrocyclic complex units are linked by silver(i) ions outside the cavity via endo–exo-coordination. The larger ring cavity along with the flexible nature of L2 may induce the weaker endocyclic complexation and contribute to exocyclic coordination as well. In NMR titration studies for the corresponding complex system, however, no evidence of exocyclic coordination was observed. Instead, L1 and L2 form a stable endocyclic 1 : 1 silver(i) nitrate complex, with a higher affinity for the former ligand.