Synthesis, Crystal Structure and DFT Studies of a New Dinuclear Ag(I)-Malonamide Complex

The synthesis and structural aspects of a new dinuclear silver (I) complex with malonamide type ligand (L) is reported. Each Ag ion in the [Ag(2)L(2)(NO(3))(2)]·H(2)O complex is coordinated to two ligands, L, each acting as a bridged ligand via its two pyridine arms; Ag(I) acts as a connector between them. Two types of Ag-ligands close contacts were detected: Ag–N1, Ag–N4 from the two L units, and Ag–O5, Ag—O6 from the two nitrate anions, wherein both the nitrate ions are inside the cage formed by the [Ag(2)L(2)] unit. The coordination geometry around each Ag(I) is a distorted tetrahedron. The [Ag(2)L(2)(NO(3))(2)] complex units are connected by weak intermolecular C—H…O interactions. The different intermolecular interactions were quantified using Hirshfeld surface analysis. Using two DFT methods (B3LYP and WB97XD), the nature and strength of the Ag–N and Ag–O interactions were described using atoms in molecules (AIM) and natural bond orbital (NBO) analyses. Topological parameters indicated that the strength of the two Ag–N bonds was similar, while that of the two Ag–O interactions were significantly different. Moreover, the Ag–N interactions have a predominant covalent character, while the Ag–O interactions are mainly ionic. The NBO analysis indicated that the most important anti-bonding Ag-orbital in these interactions has an s-orbital character.