Theoretical analyses of chemical bonding in terminal EThF2 (E = O, S, Se, Te)

Analyses of chemical bonding and geometric structures in species with chalcogen elements EThF2 (E=O, S, Se, Te) are performed by the density functional theory. Kohn-Sham molecular orbitals and Th-E bond lengths of these species both indicate multiple bond character for the terminal chalcogen complexes. This is also confirmed by natural bond orbital analyses using the one-electron density matrix generated by relativistic density functional calculations. Theoretical analyses indicate that electron donation from E to Th increases down the chalcogen group (O<S<Se<Te). These molecules can serve as examples of multiple bonding between actinide elements and selenium or tellurium.