Regioselectivity of reduction of nitro groups in 3, 5-dinitrosalicylic acid monohydrate explored by experimental and theoretical charge density analysis

Abstract

Preferential reduction of one of the two nitro groups in 3, 5-dinitrosalicylic acid monohydrate has been investigated using experimental charge density analysis from a high-resolution X-rays diffraction data at 100K combined with DFT theoretical calculations. The structure was refined using the classical Independent Atom Model as well as the Multipolar Atom Model. Bond characterization is performed in terms of charge density distribution and the associated topological properties. The theoretical (B3LYP/6-311++G(d,p), SMD/water) electrostatic potential molecular surfaces and atomic charges complimented the mechanism where one of the two nitro groups with higher negative charge gets preferentially reduced. The weak intermolecular interactions and hydrogen bonding are further quantified by the Hirshfeld surface analysis.