Effect of Symmetry State and Electron Delocalization on the Conformational and Structural Properties of S2X2 (S2F2/S2Cl2/S2Br2)

Disulfide dihalides with XYYX structures [S2F2 (1), S2Cl2 (2), S2Br2 (3)] have ground state skew (C2) and transition state trans (C2h) and cis (C2v) conformations. Natural bond orbital (NBO) analysis have shown that the stability energy is higher for LP2S2 → $$\sigma _{{{\text{S3}} - {\text{X4}}}}^{*}$$ electron delocalization from donor to acceptor orbitals in the form of skew. The generalized anomeric effect (GAE) associated with LP2S2 → $$\sigma _{{{\text{S3}} - {\text{X4}}}}^{*}$$ (* – anti bonding symbol) and LP3X4 → $$\sigma _{{{\text{S2}} - {\text{S3}}}}^{*}$$ electron delocalization of GAE (C2)-GAE (C2h) and GAE (C2)-GAE (C2v) decreased from compound 1 to 3. ΔWBI, ΔG, ΔH, ΔE0 and Δη and the conformational and structural characters of compounds 1 to 3 were calculated and discussed by various ab initio methods.