Three electron bonds. I. The H2SSH radical cation

Ab initio molecular orbital calculations are reported for H2S, its radical cation, and the H2SSH radical cation. At the MP2/4‐31G level the SS three‐electron bond is 2.85 Å long, and has a dissociation energy of 31.2 kcal mole−1. The performance of MNDO semiempirical molecular orbital theory is compared with the ab initio results.