Counteranion's effects on the structures of supramolecular silver coordination compounds of one asymmetric and one biting organic ligands

Abstract

Reactions of one asymmetric ligand 1,6-dihydro-2-methyl-6-oxo-(3,4′-bipyridine)-5-carbonitrile (L¹) with AgX (X = NO₃⁻, BF₄⁻, AsF₆⁻, SbF₆⁻) afforded two 1-D interpenetrating coordination polymers {[Ag₂(L¹)₃]₂·(CH₃OH)₃·(AsF₆)₄}_n (1) and {[Ag₂(L¹)₃]₂·(SbF₆)₄}_n (2), and two monomers [Ag(L¹)₂]·(NO₃) (3) and [Ag(L¹)₂]·(CH₃OH) (BF₄) (4). The structural similarity between compounds 1 and 2, and the structural difference between compounds 1 and 2 and compounds 3 and 4 give evidences that the sizes of counteranions with the same polyhedron sometimes can not affect the supramolecular structures, but the polyhedra of counteranions sometimes can. The self-assembly of one angular ligand 1,3,4-thiadiazole-2,5-di-2-pyridyl (L²) with AgX (X = BF₄⁻, ClO₄⁻, PF₆⁻, AsF₆⁻, NO₃⁻, SbF₆⁻) produced five di-nuclear and one mono-nuclear silver(I) coordination compounds. In the three dinuclear compounds [Ag₂(L²)₂](BF₄)₂ (5), [Ag₂(L²)₂](ClO₄)₂ (6), and [Ag₂(L²)₂](PF₆)₂ (7), there are medium Ag–Ag interactions between two adjacent dimers, leading to a 1-D supramolecular chain. In the other two dimers [Ag₂(L²)₂](AsF₆)₂ (8) and [Ag₂(L²)₂](NO₃)₂(CH₃OH) (9), however, no Ag–Ag interactions were found. When changing counteranion to the very large one SbF₆⁻, the silver complex of L² is a monomer [Ag(L²)₂](SbF₆) (10). The supramolecular structural diversity of compounds 7, 8, and 10, resulting from the volume changes of the octahedral counteranions shows that the sizes of counteranions with the same polyhedron can sometimes affect the supramolecular structures.