Density functional theory study of Te(CN)2, Te(CN)(NC), and Te(NC)2 and their isomerizations

Abstract

The equilibrium structures of Te(CN)2, Te(CN)(NC), and Te(NC)2 and three isomerization reactions: Te(CN)2 ⇌ Te(CN)(NC), Te(CN)(NC) ⇌ Te(NC)2, and Te(CN)2 ⇌ Te(NC)2 were studied in the gas-phase using density functional theory. Three functionals (B3LYP, BLYP, and BHLYP) were employed to characterize the low-lying electronic singlet and triplet TeC2N2 isomers. The basis sets for carbon and nitrogen used were of double-ζ plus polarization quality with additional s- and p-type diffuse functions, DZP++. For the tellurium atom, the LANL2DZ (ECP) basis set was used. The energetic ordering (kcal mol−1) (B3LYP) including zero-point vibrational energy corrections for the singlet ground state isomers follows: Te(CN)2 (0.0, global minimum) < Te(CN)(NC) (15.4) < Te(NC)2 (29.8). Electrostatic potentials and average local ionization energies of the ground state Te(CN)2, Te(CN)(NC), and Te(NC)2 isomers provide some guidance as to sites for noncovalent and covalent interactions. Energetics such as the different forms of electron affinities, ionization energies, and singlet–triplet gaps were also reported. Further the theoretical rate constants for the isomerization reactions were evaluated using transition state theory. We predict that these isomers may crystallize in similar patterns, if stable, as does Se(CN)2.