Synthesis, spectral, structural and Hirshfeld surface analysis of bis(5-ammonium isophthalic acid) hexabromostannate(IV) tetrahydrate hybrid

Abstract

A Tin(IV)-5-ammonium isophthalic acid hybrid has been successfully synthesized at room temperature using 5-ammonium isophthalic acid hydrobromide and tin (IV) bromide as precursors. Single-crystal X-ray diffraction analysis reveals that the compound crystallizes in a triclinic system with a centrosymmetric space group Pī, where the asymmetric unit consists of one [C₈H₈NO]⁺ cation, half of a [SnBr₆]²⁻ anion, and two water molecules. The crystal cohesion is reinforced by a network of intermolecular interactions, including N–H⋯Br, O–H⋯Br, N–H⋯O, and O–H⋯O hydrogen bonds, which play a crucial role in stabilizing the crystal structure and ensuring its integrity. BVS calculations performed on SnBr₆²⁻ anion resulted in 3.95, it is conclusively shown that tin's near the formal oxidation state is 4+. At room temperature, diffuse reflectance spectral measurements indicated a band gap of 2.93 eV. The ¹H and ¹³C NMR analyses reveal distinct chemical shifts and broadening due to coupling effects, providing critical insights into the structural arrangement and interactions within the compound. Fingerprint plots have been utilized to identify and quantify the percentage of hydrogen bonding interactions.