DFT, AIM, AND NBO ANALYSES OF 1-METHYL-2- THIOXOIMIDAZOLIDIN-4-ONE TAUTOMERS
AND THEIR COMPLEXES WITH IODINE

Journal of Structural Chemistry. Vol. 53, No. 4, pp. 649-658, 2012

H. Tavakol,1 T. Hadadi,2 and H. Roohi3 UDC 541.6:541.49:547.33

Abstract
Thioimidazoline derivatives can be used to treat hyperthyroidism due to their ability to make complexes with iodine. In this research designed to find new structures with the same ability, 1-methyl-2- thioxoimidazolidin-4-one (MTIO) and the structures of MTIO tautomers (5 tautomers), their isomers (total 9 isomers) and their complexes with iodine are optimized using the B3LYP method with two different basis sets to obtain their molecular parameters, relative energies, and vibrational frequencies. The relative energies show that in all tautomers and complexes, ketone and thione forms are more stable than enol and thienol forms, and also Z isomers are more stable than E isomers. Moreover, the NBO calculation is carried out for tautomers and complexes to obtain atomic charges and acceptor-donor interactions. These results confirm the ability of MTIO tautomers to form complexes and show that the planar complexes have more effective interaction than the perpendicular complexes. The essence and important complexation properties are also calculated and confirmed using the AIM analysis.