Computational characterization of the charge transfer (CT) and T-shaped molecular complexes of N-methyl imidazoline-2-thione and N-methyl imidazolidine-2-thione with the dihalogens Br2 and I2

Agnie M Kosmas (1) , Demetrios K Papayannis

1 Department of Chemistry [Ioannina]

The computational characterization of the molecular complexes of N-methyl imidazoline-2-thione (methimazole) and the related saturated analog, N-methyl imidazolidine-2-thione with Br2 and I2 is carried out using quantum mechanical electronic structure methods. Two kinds of molecular connectivity have been examined. The first displays a collinear S-X-X geometry (X=Br, I) and leads to charge-transfer type (CT) adducts, possible in two stereoisomeric conformations depending on the direction of the X2 axis, either planar or perpendicular to the NCS plane. The second kind correspondsto T-shaped hypervalent complexes in which sulfur is connected to both X atoms forming the linear X-S-X arrangement. The structural changes, the spectroscopic findings, the NBO analysis and the examination of the MO second order perturbation energies give interesting information about the nature of the halogen bonding interaction between the electron donor organic species and the electron acceptor dihalogen molecule. Similar trends are followed by the energy and relative stability results including BSSE corrections, which show the larger stabilization of the planar CT conformers of both dihalogens vs. the perpendicular configurations. They also indicate the higher stability of the T-shaped bromine complexes relative to the CT species, opposite to the energy order of the corresponding diiodine adducts. A critical comparison is carried out with literature results on similar systems.

Mots clés: Physical Sciences

Agnie M Kosmas, Demetrios K Papayannis. Computational characterization of the charge transfer (CT) and T-shaped molecular complexes of N-methyl imidazoline-2-thione and N-methyl imidazolidine-2-thione with the dihalogens Br2 and I2. Molecular Simulation, 2010, 36 (03), pp.212-220. ⟨10.1080/08927020903186592⟩. ⟨hal-00568946⟩