Variability in the structures of luminescent [2(Aminomethyl)pyridine] silver(I) complexes:: Effect of ligand ratio, anion, hydrogen bonding, and π-stacking

The reaction of 2-(aminomethyl)pyridine (2-amp) with silver(I) salts of triflate (OTf-), trifluoroacetate (tfa(-)), and tetrafluoroborate (BF4_) produce monomeric, dimeric, bridged, and polymeric structural motifs. The structural characteristics are dependent upon the ratio of ligand/metal in the structure as well as the ability of the anion to coordinate to the metal centers and form hydrogen bonds to the bound ligands. The silver coordination environment takes on several geometries including near linear (6), trigonal (4), tetrahedral (1), and both trigonal-bipyramidal and square-based pyramidal in a single structure (2). Structures 2, 3, and 5 also display short Ag-Ag contacts ranging from 2.8958(3) to 3.0305(4) angstrom. The species with metal-metal interactions, which are connectively very similar to their metal-isolated counterparts of 1, 4, and 6, are held together only by weak pi-stacking interactions or hydrogen bonds to their respective anions. Low-temperature luminescence spectra were collected for all compounds and are compared.