The structures and stability of HPOS isomers

A singlet potential energy surface (PES) of HPOS system including eighteen isomers, twenty-five transition states and dissociation fragments has been investigated at MP2/6-311 + + G(d, p) and QCISD(T)/6-311 + + G(3df, 2p) (single-point) levels of theory. The structures and isomerizations of the optimized isomers are discussed, while their possible dissociation pathways are predicted, hi all the optimized isomers, eight species, i. e., cis-HOPS, trans-HOPS, trans-HSPO, cis-HSPO, HP(O)S(C₈), trans-HPSO, cis-HPSO and HP(O)S(C₁), can be considered as kinetically stable isomers, and may be detected experimentally. The calculated results indicate that the stronger hypervalent capacities of P and S play an important role in decreasing the energy and increasing kinetic stability of isomers. The comparison among HPOS system and its analogs, HPO₂, HPS₂ and HNOS, is made.