Reactivity of Acetylbarbituric Thiosemicarbazone Derivatives with Silver(I) Nitrate and the Influence of Substituents at Nitrogen Atom 4N on the Bonding and Nuclearity of the Resulting Silver(I) Complexes

The reactions of silver-(I) nitrate with N-substituted thiosemicarbazones derived from 5-acetylbarbituric acid (H2Acb4R, R = NH2, NHCH3, N-(CH3)2, piperidine (Pip), or hexamethylenimine (hexim) in the presence of triphenylphosphine and triethylamine form a series of silver-(I) complexes with various structural motifs and different coordination geometries at the metal, with the composition [Ag-(PPh3)2(HAcb4NH2)] (1), [Ag-(PPh3)3(HAcb4NH2)]·EtOH·H2O (2), Ag-(PPh3)-(H2Acb4NHM)-(NO3)·2H2O (3), [Ag-(PPh3)3(HAcb4NHM)]·2EtOH (4), Ag-(PPh3)-(H2Acb4NHM)2(NO3)·3H2O (5), [Ag-(PPh3)3(HAcb4NDM)]·3EtOH (6), [Ag-(PPh3)3(HAcb4NDM)]·2DMSO·H2O (7), [Ag-(PPh3)-(HAcb4Pip)]3·4.5H2O (8) and [Ag-(PPh3)3(HAcb4Hexim)]·3EtOH·3H2O (9), and {[Ag-(H2O)14]-(NO3)}-n, [Ag-(PPh3)4]-(NO3)·EtOH, [AgCl-(PPh3)]4 as byproducts. In many cases, polycrystalline samples of these compounds were characterized using elemental analysis, FT-IR, UV-Visible, 1H, 13C-{1H} and 31P-{1H} NMR spectroscopy, FAB-MS, and single-crystal X-ray crystallography. The spectroscopic properties and structures of these compounds, except 1, 3, and 5, are discussed. Various hydrogen-bonding interactions, such as N-H···O, O-H···O, C-H···O, and π-π stacking interactions, contribute to the crystal packing. The influence of these weak interactions has been addressed with the help of Hirshfeld surface analyses and further analyzed using DFT calculations and Bader's theory of atoms-in-molecules.