Anion-assisted silver(I) coordination complexes from flexible unsymmetrical bis(pyridyl) ligands: Syntheses, structures and luminescent properties

摘要

The reaction of AgX (X = NO_3 ~- and ClO _4 ~-) salts, triphenylphosphine (PPh_3) and four flexible unsymmetrical bis(pyridyl) ligands, namely N-(pyridin-2-ylmethyl) pyridin-2-amine (L1), N-(pyridin-3-ylmethyl)pyridin-3-amine (L2), N-(pyridin-2-ylmethyl)pyridin-3-amine (L3) and N-(pyridin-4-ylmethyl)pyridin-3- amine (L4), leads to the formation of six complexes, [Ag_2(L1) _2(ClO_4)_2]_n (1), [Ag _2(L_2)_2(ClO_4)_2]_n· n(CH_3CN) (2), [Ag(L1)(NO_3)]_n (3), [Ag(L2)(NO_3)]_n (4), [Ag(L3)(NO_3)(PPh _3)]_n (5) and [Ag(L4)(NO_3)(PPh _3)]_n (6), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. In contrast to the chain structure of complexes 1 and 2, induced by the weakly coordinated perchlorate anion, the nitrate anion can coordinate to the Ag(I) cation in monodentate, chelating and even more intricate μ_2- κ~3 modes, thus defining dinuclear (complex 3), various chain motif (complexes 5 and 6) and layer structures (complex 4). The four ligands in the six complexes present diverse cis-cis, cis-trans and trans-trans conformations, which are responsible for the structural diversities and, together with the nature of the inorganic anions, the coordination spheres of the Ag(I) cations. Moreover, solid-state luminescent properties demonstrate that the emission intensities of the perchlorate-containing complexes are stronger than those of the nitrate-containing complexes.