Computational Methods and Molecular Modelling for Some Predicted Tautomers of Pyrimidine compounds
Introduction: Several molecular modelling techniques and quantum chemical methods have been performed to correlate the chemical structures of the compounds with their physical molecular properties. Methods: Using theoretical parameters help to characterize the molecular structure of the investigated ligands and to study their equlibria mechanism. Molecular modelling data such as the bond length, bond order, bond angles and dihedral angles values were estimated for some pyrimidine compounds, where the data suggested the presence of tautomerism and a dynamic equilibria are deduced between all the detected tautomers in the solid state. Results: Four main tautomers are predicted for barbital and thiobarbituric acid while three tautomers are for thiouracil. Quantum chemical parameters such as the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (µ ), sum of the total negative charge (STNC), electronegativity (Χ), chemical potential (Pi), global hardness (η) and softness (σ ) were calculated.