Ensslin, WaltherBock, HansBecker, Gerd2010-10-192016-03-312010-10-192016-03-311974348346271http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-57238http://elib.uni-stuttgart.de/handle/11682/7403http://dx.doi.org/10.18419/opus-7386The photoelectron (pe) spectra of mono- and disubstituted silyl- and methylacetylenes are assigned by comparison with the corresponding ionization potentials of acetylene, disilane, and ethane. The observed π splittings can be rationalized within a parameterized hyperconjugation model. Calculations using a modified CND0/2 procedure with and without inclusion of 3d orbitals in the basis set demonstrate that the usual parameters tend to overemphasize p,d, back-bonding. To rationalize available experimental data, 3d si orbitals need not to be considered explicitly-neither for the different dipole moments of methyl- and silylacetylenes nor for the general pe spectroscopic pattern of silicon compounds, i.e., high first ionization potential, reduced spin-orbit coupling, or band broadening.eninfo:eu-repo/semantics/openAccessAlkine , Substitutionsreaktion , Photoelektronenspektroskopie540article2011-08-08