Theoretical analysis of the interactions of 2,3-dihydro-3-methyl-2-thioxopyrimidin-4(1H)-one tautomerswith iodine
DFT and ab initio theoretical methods were used to calculate the relative stability of 2,3-dihydro-3-methyl-2-thioxopyrimidin-4(1H)-one molecule (DH-3Me-TPO) and its tautomers, also complexes of it with iodine. This molecule (T) has four tautomers (T1, T2, T3, and T4) and can be used for treatment of hyper thyroidism because of its ability to build complexes with iodine. All tautomers and complexes are optimized using the B3LYP method in conjunction with 6-31+G** and 6-311++G** basis sets. Results indicate that in all tautomers and complexes thione form is more stable than thiol ones. The NBO calculation is carried out on optimized tautomers and complexes to obtain atomic charges and donor-acceptor interaction energies. Results confirm the ability of T tautomers to form complexes and show that the planar complex has more effective interaction than the perpendicular one. The atoms in molecules (AIM) analysis show that the electron charge density (iÂ²) and its laplacian ( 2iÂ²) at the S-I bond critical point of the planar complex is greater than the perpendicular one.