Silver(i) supramolecular complexes generated from polydentate ligands containing cyano and pyridyl groups

Abstract

A series of silver(I) complexes of the type {[Ag(L1)][X]}_∞ (L1 = 2,6-dimethyl-3,5-dicyano-4-(4-pyridyl)-1,4-dihydropyridine; X = BF₄⁻, 1; ClO₄⁻, 2; and NO₃⁻, 3); {[Ag₂(L2)₄][SO₄]}_n, 4; and [Ag₂(L2)₂(NO₃)₂]_n, 5 (L2 = 2,6-dimethyl-3,5-dicyano-4-(3-pyridyl)-1,4-dihydropyridine) have been prepared by reactions of various Ag(I) salts with L1 or L2 in MeOH–H₂O. All the complexes have been structurally characterized by X-ray crystallography confirming that complexes 1–3 are two-dimensional coordination polymeric nets, while complexes 4 and 5 are one-dimensional coordination polymeric chains. All the L1 ligands in complexes 1–3 act as tridentate ligands to bridge Ag(I) ions. The anions BF₄⁻ and ClO₄⁻ in complexes 1 and 2 are not coordinated to the Ag(I) atoms while the NO₃⁻ anions in complex 3 are coordinated to the metal centers through one of the three oxygen atoms. The tridentate L2 ligands in complex 4 bind soft acid Ag(I) ions through the cyano and pyridyl groups forming the 1-D polymeric chain, while in complex 5, the L2 ligands bind to Ag(I) centers in bi- and tri-dentate coordination modes. The SO₄²⁻ anions in complex 4 are not coordinated to the Ag(I) atoms whereas the NO₃⁻ anions in complex 5 are coordinated to the metal centers through one of the three oxygens. The anions in complexes 4–5 play important roles in linking cationic chains or layers into 3-D supramolecular structures.