Air and moisture stable covalently-bonded tin() coordination polymers

Four covalently-bonded tin( ii ) coordination polymers, (1)-(4) , were hydrothermally prepared in aqueous alkaline media by the reactions of SnSO 4 with 1,2,4,5-benzenetetracarboxylic acid (1) , 1,3,5-benzenetricarboxylic acid (2) , 4-hydroxypyridine-2,6-dicarboxylic acid (3) , and 1,3,5-cyclohexanetricarboxylic acid (4) . All products were structurally authenticated by single-crystal X-ray diffraction, and the number of different tin centres and their oxidation states were confirmed by 119 Sn Mössbauer spectroscopy. In addition, the comparison between experimental and simulated X-ray powder diffraction patterns confirmed the authenticity of the samples. Our crystallographic results for (1)-(4) show that the Sn( ii ) centres are tetracoordinated and exhibit distorted disphenoidal geometries, corroborating the presence of one stereochemically active lone electron pair at each metal site. Products (1) and (2) display bi-dimensional polymeric structures, (3) exhibits a one-dimensional architecture, whereas (4) shows a remarkable three-dimensional coordination network. Hirshfeld surface and supramolecular analyses for the repeating units of (1)-(4) were also performed in order to identify structurally important non-covalent interactions. Compounds (1)-(4) display 1D, 2D or 3D coordination networks, in which the Sn( ii ) cations exhibit distorted disphenoidal geometries due to the stereochemically active electron lone pairs.