The silaformyl radical HSiO and its energetically lower-lying isomer SiOH

Ab initio investigations with a double-zeta plus polarization basis set extended by configuration interation (single and double excitations) predict that the SiOH isomer is 11 kcal/mol lower in energy than HSiO. The barrier for hydrogen rearrangement is found to be substantial and both isomers should be observed experimentally. Two structures HSiO(A) and HSiO(B) were detected for HSiO with ²A′ symmetry and nearly the same energy but different geometry at the DZ+P SCF level. However, HSiO(A) is clearly favored relative to HSiO(B) at higher levels of theory and might be the only true minimum for HSiO.