Crystalline hydrates and polymeric Ag(I) complexes of isomeric flexible double betaines 1,4-bis( n-picolyloxyl)benzene- N, N′-diacetate ( n = 2,3,4)

Abstract

The isomeric flexible double betaines 1,4-bis(2-picolyloxyl)benzene- N, N′-diacetate (L 1), 1,4-bis(3-picolyloxyl)benzene- N, N′-diacetate (L 2) and 1,4-bis(4-picolyloxyl)benzene- N, N′-diacetate (L 3) were used to react with AgNO 3, affording coordination polymeric complexes {[Ag 2L 1](NO 3) 2 · 3.5H 2O} n ( 1), {[Ag 2L 1](NO 3) 2 · 6H 2O} n ( 2) and {[Ag 3L 3](NO 3) 3 · 3H 2O} n ( 3). The crystal structures of the betaine hydrates L 1 · 8H 2O, L 2 · 6H 2O, L 3 · 5H 2O and the silver(I) complexes have been determined. L 1 · 8H 2O consists of a hydrogen-bonded three-dimensional network, whereas both L 2 · 6H 2O and L 3 · 5H 2O feature hydrogen bonded two-dimensional frameworks. In complex 1, the Ag(I) ions in the dimeric unit have different coordination environments; through the linkage of L 1 ligands and nitrates, the dimeric units are extended into a polymeric double chain. In complex 2, each Ag(I) ion of the centrosymmetric dimeric unit adopts a severely distorted tetrahedral coordination geometry; the dimeric subunits are connected by the L 2 ligands, giving an infinite one-dimensional chain, and the chains are further connected through hydrogen bonding to generate an infinite three-dimensional network. In complex 3, three Ag(I) ions constitute an isosceles triangle consolidated by weak Ag⋯Ag interactions, and such trinuclear subunits are further connected by the L 3 ligands, nitrate ions and water molecules through coordination and hydrogen bonding, yielding a three-dimensional network.