Electronic structure and force constants of the dithionitronium cation NS 2+

Abstract

The standard GF method was employed to determine the valence force constants of the dithionitronium cation (NS 2 +), using the experimental IR and Raman frequencies. The calculation force constants ( f NS = 8.256, f NS,NS = 0.663 and f SNS = 0.236 mdyn Å −1) reproduce well the 32SN 34S + frequencies and suggest a bond order greater than 1, as well as a delocalization of the π electrons in the trinuclear system. CNDO/2 calculations reveal positive charges on sulfur atoms, contrary to simple valence electron count rules. The CNDO/2 preferred geometry is D ∞h rather than a C 2V cyclic structure, in agreement with the X-ray diffraction data. A very important S⋯S interaction has been found.