Ortho-, meta-, and para-pyridyl oximinoacetoacetates and silver(I)-oximinoacetoacetate networks: Synthesis and X-ray crystallographic analyses

A series of novel oximinoacetoacetate ligands, ortho-, meta-, and para-pyridyloximinoacetoacetates, HL1, HL2 and HL3, respectively, have been synthesized and structurally characterized. Ligands HL2 and HL3 were further used for the synthesis of three new silver(I) complexes: [Ag(HL2)2]·NO3 (1) a pincer-type mononuclear complex, [Ag2(L2)2(HL2)2] (2) a centrosymmetric dimer complex, and [Ag(L3)(HL3)]n (3) a two-dimensional coordination polymer. The ligands, with multiple hydrogen donor and acceptor atoms for the formation of non-covalent hydrogen bonding interactions in the solid state, resulted in the formation of one-dimensional hydrogen bonded chains and helices. The structural studies of the AgI compounds reveal that these ligands can be efficiently used to construct hydrogen bonded two-dimensional networks. In complex 1 an extended two-dimensional network was formed through hydrogen bonds involving the OH group of the oximinoacetoacetate ligand and an O-atom of the NO3− counter anion. Complex 2 assembled into a two-dimensional multi-layered supramolecular network via O–H⋯O hydrogen bonds involving two ligand molecules. In the case of complex 3 a two-dimensional coordination polymer was formed. Unlike in complexes 1 and 2, here no classical hydrogen bonding interactions were observed in the crystal. The presence of non-classical C–H⋯O and C–H⋯N hydrogen bonds leads to the formation of three-dimensional networks in the crystal structures of all three complexes.