Abstract
Isatin oxamohydrazide (L) reacted with the aqueous solution of silver nitrate at room temperature afforded the polymeric silver(I) nitrato complex, [Ag2L′(NO3)2]n, (1) of the azine ligand (L′). Similarly, the reaction of L with silver(I) perchlorate gave the [Ag2L′2(ClO4)2]n, (2) coordination polymer. Careful inspection of the crystals from the nitrato complex preparation showed the presence of another crystalline product which is found to be [Ag(Isatin-3-hydrazone)NO3], (3) suggesting that the reaction between silver(I) nitrate and L proceeds first by the hydrolysis of L to the isatin hydrazone which attacks another molecule of L to afford L′. Testing metal salts such as Ni2+, Co2+, Mn2+, Cu2+ and Cd2+ did not undergo any reaction with L either under the same reaction conditions or with heating under reflux up to 24 h. Treatment of the warm alcoholic solution of L with few drops of 1 : 1 (v/v) hydrochloric acid gave the free ligand (L′) in good yield. The [Ag2L′(NO3)2]n complex forms a two-dimensional infinite coordination polymer, while the [Ag2L′2(ClO4)2]n forms one-dimensional infinite chains with an alternating silver-azine backbone. Quantitative analysis of the intermolecular interactions in their crystals is made using Hirshfeld surface analysis. Density functional theory studies were performed to investigate the coordination bonding in the studied complexes.
Highlights
Silver and silver compounds attract great interest from researchers for many reasons
The role of silver ion was to increase the electrophilicity of carbonyl hydrazide carbon and/or to increase the acidity of methanol, so that the hydrazide group was hydrolysed and the resulting hydrazino group could subsequently attack hydrazone carbon in another oxamohydrazide molecule in which Ag(I) might increase its electrophilicity, resulting in the azine product
Via self-assembly, three silver(I) complexes were synthesized by direct mixing of isatin oxamohydrazide (L) and silver(I) salts in the water/methanol solution at room temperature
Summary
Silver and silver compounds attract great interest from researchers for many reasons. They have interesting antimicrobial actions [1,2,3,4]. We report, for the first time, the silver(I) catalysed hydrolytic reaction of the oxamohydrazide L to the corresponding azine ligand L and in situ complexation with Ag(I) via selfassembly (scheme 1). The reactions form polymeric silver(I) complexes with the azine-type ligand (L ) at room temperature in the water/methanol mixture. Trial to synthesize the ligand (L ) is succeeded by the direct reaction of the hot alcoholic solution of oxamohydrazide (L) in the acidic medium (1 : 1 v/v HCl), under reflux for 1 h. The Ag–N and Ag–O coordination interactions were investigated in the framework of atom in molecules (AIM) and natural bond orbital (NBO) analysis
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