The energetics of formation and X-ray crystal structure of SNSNS(AsF6)2, containing the lattice-stabilized aromatic 6π 1,3,4,2,5-trithiadiazolium(2+) cation formed by the crystal-lattice-energy-driven, symmetry-allowed cycloaddition of SN+ and SNS+

Abstract

We report the preparation, vibrational spectra and X-ray crystal structure of [graphic omitted](AsF₆)₂, containing the 6π 1,3,4,2,5-trithiadiazolium(2+) cation, which dissociates in solution to SN⁺ and SNS⁺, consistent with ab initio 6–31G* calculations (estimated gas-phase dissociation enthalpy: –400 kJ mol^–1); the [graphic omitted]²⁺ ring represents a local energy minimum, and the cycloaddition of SN⁺ and SNS⁺ is driven in the solid state by the high lattice energy of the 1 : 2 salt.