Using density functional theory, 13CNMR chemical shifts, IR spectra, electrode potential and structural parameters of 6,7-dihydroxy-9- thia-1,4a-diaza fluoren-2-one (DTDFO) as an important derivative of the thiadiazaflourenone compounds are calculated. The calculated electrochemical properties are compared with those obtained by cyclic voltammetry showing 9% and 6% error for the MPW1PW91 and B3LYP levels of theory, respectively. Furthermore, actual IR and 13CNMR spectra are obtained and compared with the theoretical results at both the levels; linear correlations between the experimental IR and 13CNMR data and their corresponding theoretical ones are found with R2 > 0.90. Other helpful descriptors such as Fukui functions, delocalization stability energies, and molecular electrostatic potentials are used to characterize the reactivity and electronic properties of the title structure. The two employed computational methods, namely B3LYP/6-311++G(d,p) and MPW1PW91/6- 311++G(d,p) are also compared with each other. Statistical methods such as root mean squared errors (RMSE), and mean absolute errors (MAE) are adopted to measure the errors arising from the computations. In conclusion, an acceptable agreement between the theoretical and experimental data shows the reliability of the employed computational methods in this study. Moreover, this work provides a detailed theoretical insight into the different aspects of DTDFO, some of which are supported by experimental evidence.
