Pre-organisation of ligand donor sets modulates the supramolecular structure of bis(pyridyl–imine) silver(i) chelates

Abstract

Three bis(pyridyl–imine) ligands 1,2-bis(2-pyridyliminomethyl)benzene (L1), 1,3-bis(2-pyridyliminomethyl)benzene (L2) and 1,4-bis(2-pyridyliminomethyl)benzene (L3) were synthesised and complexed to silver(I) salts forming four novel complexes; 1,2-bis(2-pyridyliminomethyl)benzene-silver(I) hexafluoroantimonate(V) [Ag(L1)](SbF₆), bis(1,3-bis(2-pyridyliminomethyl)benzene-di-silver(I)) bis(hexafluoroantimonate(V)) [Ag₂-μ-(L2)₂](SbF₆)₂, catena-1,4-bis(2-pyridyliminomethyl)benzene-silver(I) hexafluoroantimonate(V) [Ag-μ-(L3)](SbF₆) and catena-1,4-bis(2-pyridyliminomethyl)benzene-silver(I) tetraphenylborate(III) [Ag-μ-(L3)](BPh₄). All four complexes were characterized by ¹H and ¹³C NMR, IR, mass spectrometry and UV/visible spectroscopy as well as X-ray crystallography. The ligands were designed to preorganise the atom donor sets to control the structures of the metal chelates. The pre-organised ligands control the supramolecular structure of the bis(pyridyl–imine) silver(I) chelates, which results in the formation of a monomeric structure for chelate [Ag(L1)](SbF₆), a dimeric structure for chelate [Ag₂-μ-(L2)₂](SbF₆)₂, and polymeric structures for chelates [Ag-μ-(L3)](SbF₆) and [Ag-μ-(L3)](BPh₄). The d¹⁰ electronic configuration of silver allows the metal ion to adopt both tetrahedral and square planar coordination geometries in the above compounds, assisting the formation of the various compounds. Additionally, the stabilising effects of the intermolecular interactions were studied using DFT methods.