The role of the sulfur d-orbital exponent (αd) is analysed on a series of selected compounds, such as, SH2, SF2, SOH2, SO2, SO2H2, SO3 and SH4, in which sulfur has different formal valences. Closed shell Hartree-Fock calculations have been done using the split valence 3-21G basis set augmented with a single d-function for sulfur. The changes of total energy, geometry, bond order and valence indices are monitored as a function of αd. It is noted that d-orbitals do not have any significant effect in the case of normal valence (bivalent) sulfur compounds but, in the case of hypervalent compounds (where the contributing resonance structures cannot be described without the inclusion of d-orbitals) and in formal hypervalent compounds, they make a substantial difference. One can obtain both the proper geometry and bonding characteristics if two d functions are added on the S atom, with exponents around 0.7 and 0.3.
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry