Anion-dependent soft metal complexes with an O2S3-macrocycle: From monomer and dimer to polymer with endo-, exo-, and endo/exocyclic coordination modes

Abstract

Listen

Translate article

Five soft metal complexes (1–5) of a 16-membered O2S3-macrocycle (L) with different topologies and coordination modes, including discrete to infinite forms, and endo-, exo-, and endo/exo-coordination, were prepared and structurally characterized. Both mercury(II) complexes, [Hg(L)(NO3)2] (1) and [Hg(L)(DMF)2](ClO4)2·DMF (2), with nitrate and perchlorate anions, respectively, show a typical endocyclic structure. Two nitrate ions in 1 occupy the coordination sites, while two DMF molecules participate to the coordination sphere in 2 remaining two perchlorate ions uncoordinated. It is found that the anion-exchange of 2 in the solid state induced the conversion to 1 which involves the rearrangement of the coordination sphere. In silver(I) complexations, nitrate afforded a cyclic dimer complex [Ag2(L)2(NO3)2] (3). While hexafluorophosphate gave a 1-D zigzag coordination polymer {[Ag(L)]PF6}n (4). Interestingly, triflate led to the isolation of a tetranuclear bis(macrocycle) complex, {[endoAg(L)(CF3SO3)]2[μ-exoAg2(CF3SO3)2]} (5), which are dominated by the coordination modes (endoAg and exoAg) of L toward two types of silver(I) centers. For instance, two endocyclic complex units, endoAg2(L)2(CF3SO3)2, are linked by exocyclic metallacycle, [μ-exoAg2(CF3SO3)2], to give a 4:2 (metal-to-ligand) stoichiometry. From the results, it is obviously clear that the role of anions mostly is responsible to such structural diversity based on the exo-coordination mode.