Electronic structure of H2CS3 and H2CS4: An experimental and theoretical study

The HeI photoelectron spectra of H2CS3 and H2CS4 in the gas phase have been obtained for the first time. A complete theoretical study involving the calculation of the ionization energies using orbital valence Green's functional (OVGF) and population analysis was performed. Calculations of cation-radical forms were carried out in order to interpret the main characters of the six highest occupied molecular orbitals (HOMOs). The first vertical ionization potentials are 8.74 and 8.56 eV for H2CS3 and H2CS4, and attributed to {9b2(nS(CS))}−1 and {8a″(3pπ(S–S)*,nS)}−1, respectively. Meanwhile, the energy sequence of three types of sulfur 3p lone-pair have been discussed: 3pπ(S−S)* < nS(CS) < n(S3p), and an energy splitting ΔE = 2.06 eV of 3pπ(S–S) and 3pπ(S−S)* orbitals in H2CS4 is observed.