Endo- and/or exocyclic silver(i) and mercury(ii) complexes of an NO2S2-macrocycle: effect of ligand ratio and anion

Abstract

Synthesis and structural behaviours of a pyridine-containing NO₂S₂-macrocycle L and its soft metal complexes 1–4 with different types of coordination modes and topologies are presented. The reactions of L with AgPF₆ in different ligand-to-metal ratios lead to the formation of two solid complexes with different topologies: an endocyclic 1 : 1 (L : M) complex 1a and an unprecedented 2 : 1 endo/exo-type complex 2. NMR titrations confirm that both silver(I) complexes with 1 : 1 and 2 : 1 ratios also retain in solution. In the reactions of L with HgCl₂ and Hg(ClO₄)₂, anion-controlled exo- and endocyclic 1 : 1 complexes were afforded, respectively. The tendency to adopt this respective arrangement suggests the possibility that metal coordination modes and/or topologies including the stoichiometries can be controlled by varying ligand-to-metal ratios and anions.