TY - JOUR A1 - Utecht, Manuel Martin A1 - Klamroth, Tillmann T1 - Local resonances in STM manipulation of chlorobenzene on Si(111)-7x7 BT - performance of different cluster models and density functionals JF - Molecular physics N2 - Hot localised charge carriers on the Si(111)-7x7 surface are modelled by small charged clusters. Such resonances induce non-local desorption, i.e. more than 10 nm away from the injection site, of chlorobenzene in scanning tunnelling microscope experiments. We used such a cluster model to characterise resonance localisation and vibrational activation for positive and negative resonances recently. In this work, we investigate to which extent the model depends on details of the used cluster or quantum chemistry methods and try to identify the smallest possible cluster suitable for a description of the neutral surface and the ion resonances. Furthermore, a detailed analysis for different chemisorption orientations is performed. While some properties, as estimates of the resonance energy or absolute values for atomic changes, show such a dependency, the main findings are very robust with respect to changes in the model and/or the chemisorption geometry. [GRAPHICS] . KW - DFT KW - cluster model KW - charge localisation KW - STM Y1 - 2018 U6 - https://doi.org/10.1080/00268976.2018.1442939 SN - 0026-8976 SN - 1362-3028 VL - 116 IS - 13 SP - 1687 EP - 1696 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - GEN A1 - Utecht, Manuel Martin A1 - Klamroth, Tillmann T1 - Local resonances in STM manipulation of chlorobenzene on Si(111)-7×7 BT - performance of different cluster models and density functionals T2 - Molecular Physics N2 - Hot localised charge carriers on the Si(111)-7×7 surface are modelled by small charged clusters. Such resonances induce non-local desorption, i.e. more than 10 nm away from the injection site, of chlorobenzene in scanning tunnelling microscope experiments. We used such a cluster model to characterise resonance localisation and vibrational activation for positive and negative resonances recently. In this work, we investigate to which extent the model depends on details of the used cluster or quantum chemistry methods and try to identify the smallest possible cluster suitable for a description of the neutral surface and the ion resonances. Furthermore, a detailed analysis for different chemisorption orientations is performed. While some properties, as estimates of the resonance energy or absolute values for atomic changes, show such a dependency, the main findings are very robust with respect to changes in the model and/or the chemisorption geometry. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 463 KW - DFT KW - cluster model KW - charge localisation KW - STM Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-412970 ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Suslova, Elena N. A1 - Tran Dinh Phien, A1 - Shlykov, Sergey A. A1 - Kleinpeter, Erich T1 - Synthesis, conformational preferences in gas and solution, and molecular gear rotation in 1-(dimethylamino)-1-phenyl-1-silacyclohexane by gas phase electron diffraction (GED), LT NMR and theoretical calculations JF - Tetrahedron N2 - 1-(Dimethylamino)-1-phenyl-1-silacyclohexane 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED), low temperature C-13 NMR spectroscopy and quantum-chemical calculations. The predominance of the 1-Ph-ax conformer (1-Ph-eq:1-Ph-ax ratio of 20:80%, Delta G degrees (317 K) = -0.87 kcal/mol) in the gas phase is close to the theoretically estimated conformational equilibrium. In solution, low temperature NMR spectroscopy showed analyzable decoalescence of C-ipso and C(1,5) carbon signals in C-13 NMR spectra at 103 K. Opposite to the gas state in the freon solution employed (CD2Cl2/CHFCl2/CHFCl2 = 1:1:3), which is still liquid at 100 K, the 1-Ph-eq conformer was found to be the preferred one [(1-Ph-eq: 1-Ph-ax = 77%: 23%, K = 77/23 = 2.8; -Delta G degrees = -RT In K (at 103 K) = 0.44 +/- 0.1 kcal/mol]. When comparing 1 with 1-phenyl-1-(X)silacylohexanes (X = H, Me, OMe, F, Cl), studied so far, the trend of predominance of the Ph-ax conformer in the gas phase and of the Ph-eq conformer in solution is confirmed. KW - 1-(Dimethylamino)-1-phenyl-1-silacyclohexane KW - Conformational analysis KW - Gas phase electron diffraction KW - Low-temperature d-NMR KW - DFT KW - MP2 KW - M062X/6-311G** calculations Y1 - 2018 U6 - https://doi.org/10.1016/j.tet.2018.06.023 SN - 0040-4020 VL - 74 IS - 32 SP - 4299 EP - 4307 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Kirpichenko, Svetlana A1 - Shainyan, Bagrat A. A1 - Kleinpeter, Erich A1 - Shlykov, Sergey A. A1 - Tran Dinh Phien, A1 - Albanov, Alexander T1 - Synthesis of 3-fluoro-3-methyl-3-silatetrahydropyran and its conformational preferences in gas and solution by GED, NMR and theoretical calculations JF - Tetrahedron N2 - The 3,3-disubstitued 3-silaheterocyclohexane with an electronegative substituent at silicon, 3-fluoro-3-methyl-3-silatetrahydropyran 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED) and low temperature C-13 and F-19 NMR spectroscopy. Quantum-chemical calculations were carried out both for the isolated species and Hcomplexes in gas and in polar medium. The predominance of the 1-FeqMeax conformer (1-F-eq:1-F-ax ratio of 65:35, Delta G degrees = 0.37 kcal/mol) determined from GED is close to the theoretically estimated conformational equilibrium, especially at the DFT level. In solution, low temperature NMR spectroscopy showed no decoalescence of the signals in C-13 (down to 95 K) and F-19 NMR spectra (down to 123 K). However, the calculated F-19 chemical shift of -173.6 ppm for the 1-FeqMeax conformer practically coincides with the experimentally observed value (-173 to -175 ppm) as distinct from that for the 1-FaxMeeq conformer (-188.8 ppm), suggesting compound 1 to be anancomeric in solution, in compliance with its theoretical and experimental preference in the gas phase. KW - 3-Fluoro-3-methyl-3-silatetrahydropyran KW - Conformational analysis KW - Gas phase electron diffraction KW - Low-temperature NMR KW - DFT KW - MP2 and CCSD(T) calculations Y1 - 2018 U6 - https://doi.org/10.1016/j.tet.2018.02.055 SN - 0040-4020 VL - 74 IS - 15 SP - 1859 EP - 1867 PB - Elsevier CY - Oxford ER -