DFT,AIMand NBOanalysis of 3-methyl-2-thioxo imidazoldin-4-one tautomers and their complexes with iodine

Author(s): TayebehHadadi, PouyaKarimi

DFT and ab initio theoretical methods were used to calculate the relative stability of complexes of 3-methyl-2-thioxoimidazoldin-4-one (3Me- TIO) with iodine. This molecule (T) has four tautomers (T1, T2, T3, and T4) and can be used for treatment of hyper thyroidism due to its ability to make complexes with iodine. All tautomers and complexes are optimized using the B3LYP method in conjunction with two different basis sets. The relative energies show that in all tautomers and complexes thione forms are more stable than thiol forms. The NBO calculation is carried out on the tautomers and complexes to obtain atomic charges and find donoracceptor interactions. These results confirm the ability of 3Me-TIO tautomers to form complexes with iodine and show that the planar complex has more effective interactions than the perpendicular one. The atoms in molecules (AIM) analysis show that the electron charge density and its laplacian at the S-I bond critical point of the planar complex is higher than the perpendicular one.

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