SIGN-IN

Publication: Singlet-triplet excitation energies of R1R2Si=Si silylene derivatives: A G4/W1BD theoretical study

All || By Area || By Year

Title Singlet-triplet excitation energies of R1R2Si=Si silylene derivatives: A G4/W1BD theoretical study
Authors/Editors* S Rayne, K Forest
Where published* Nature Precedings
How published* Other
Year* 2011
Volume
Number
Pages
Publisher Nature Publishing Group
Keywords Silylenes, Singlet-triplet excitation energies, Theoretical estimates, Gaussian-4, W1BD
Link http://dx.doi.org/10.1038/npre.2011.6465.1
Abstract
Well-to-well (WWES-T) and adiabatic (AES-T) singlet-triplet excitation energies were calculated at the Gaussian-4 (G4) and W1BD levels of theory for a suite of mono- and disubstituted R1R2Si=Si silylene derivatives (where R1/R2=H, CH3, NH2, OH, and F), as well as H2C=Si and HN=Si. Reasonable agreement was obtained with prior ES-T estimates at the CCSD(T)/6-311++G(d,p)//QCISD/6-31G(d) and B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G(d) levels of theory. The G4/W1BD ES-T are systematically higher than these prior estimates by between 1 to 5 kcal/mol, averaging positive deviations of about 1-2 and 3-4 kcal/mol from the CCSD(T) and B3LYP estimates, respectively. Qualitative ground state multiplicity agreement between the four levels of theory was found for H2C=Si, H2Si=Si, HN=Si, (H3C)HSi=Si, (H3C)2Si=Si, (H2N)HSi=Si, (H2N)2Si=Si, (HO)2Si=Si, and F2Si=Si. However, there is disagreement as to the ground state multiplicity for (HO)HSi=Si and FHSi=Si using the different theoretical methods. For (HO)HSi=Si, G4 and W1BD methods predict either a slightly energetically favored ground state singlet (G4) or an energetic degeneracy between the two multiplicities (W1BD). For FHSi=Si, both the G4 and W1BD methods predict a clear ground state singlet, whereas the CCSD(T)/6-311++G(d,p)//QCISD/6-31G(d) method predicts effective energetic degeneracy, and the B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G(d) method predicts a clear ground state triplet. In light of the current high-level calculations, the ground state multiplicities of (HO)HSi=Si and FHSi=Si should be considered uncertain due to disagreement among various levels of theory. Resolution of the actual ground state multiplicities of these compounds will likely need to await experimental data.
Go to Computational Physical Organic Chemistry For The Energy And Environmental Sciences
Back to page 7 of list