A Theoretical DFT Study on the Structural Parameters and Intramolecular Hydrogen-Bond Strength in Substituted (Z)-N-(Thionitrosomethylene)-thiohydroxylamine Systems

The effect of substitution (F, Cl, SH, NO2, CH2F, CH2Cl, CH2COOH, CH2OCH3, and SCOCH3) on the hydrogen-bond strengths, vibrational frequencies, and physical properties such as dipole moment, chemical potential, and chemical hardness of substituted (Z)-N-(thionitrosomethylene)thiohydroxylamine compound has been systematically explored. All the studied derivatives have been optimized at the B3LYP/6-311++G** level of theory in gas phase, water and carbon tetrachloride solutions. The aromaticity of the formed ring is measured through the structurally based harmonic oscillator model of aromaticity (HOMA), and the magnetic based nucleus independent chemical shift (NICS) measurements. The topological properties of the electron density distributions for S-H center dot center dot center dot S intramolecular bridges have been analyzed in terms of the Bader theory of atoms in molecules (AIM). Natural population analysis data, the electron density and Laplacian properties, as well as nu((S-H)) have been used to evaluate the hydrogen-bonding interactions. Furthermore, calculated H-1 NMR chemical shifts (delta(H)) correlate well with the hydrogen-bond distance and nu((S-H)) as well as electron density at the bond critical points in the molecular electron density topography.