Opis

• Tytuł:
  1JCH couplings in Group14/IVA tetramethyls from the gas-phase NMR and DFT structural study: a search for the best computational protocol
• Twórca:
  Nazarski, Ryszard Bolesław;
  Makulski, Włodzimierz
• Współtwórca:
  Ryszard B. Nazarski - University of Łódź, Faculty of Chemistry, Laboratory of Molecular Spectroscopy;
  Włodzimierz Makulski - University of Warsaw, Faculty of Chemistry, Laboratory of NMR Spectroscopy
• Opis:
  Accepted Manuscript;
  Four tetramethyl compounds EMe4 (E = C, Si, Ge, and Pb) were studied by high-resolution NMR spectroscopy in gaseous and liquid states at 300 K. Extrapolation of experimental vapor-phase C-H J-couplings to a zero-pressure limit permitted determining the 1J0,CHs in methyl groups of their nearly isolated molecules. Theoretical predictions of the latter NMR parameters were also performed in a locally dense basis sets/pseudopotential (Sn, Pb) approach, by applying a few DFT methods pre-selected in calculations of other gas-phase molecular properties of all these species and SnMe4 (bond lengths, C-H stretching IR vibrations). A very good agreement theory vs. experiment was achieved with some computational protocols for the all five systems. The trends observed in their geometry and associated coupling constants (1JCHs, 2JHHs) are discussed and rationalized in terms of the substituent-induced rehybridization of the methyl group (treated as a ligand) carbon, by using Bent’s rule and newly proposed, theoretically derived values of the Mulliken electronegativity (χ) of related atoms and groups. All these χ data for the Group-14/IVA entities were under a lot of controversy for a very long time. As a result, the recommended χ values are semi-experimentally confirmed for the first time and only a small correction is suggested for χ(Ge) and χ(GeMe3).;
  Publikacja w ramach programu Royal Society of Chemistry "Gold for Gold" 2014 finansowanego przez Uniwersytet Łódzki
• Dostępność obiektu:
  Dostęp otwarty
• Prawa: http://creativecommons.org/licenses/by-nc/3.0/pl ;
  Uznanie autorstwa-Użycie niekomercyjne 3.0 Polska
• Data:
  2014.06.06;
  2014.05.15
• Typ:
  Article
• Język:
  angielski
• Format:
  application/pdf
• Wydawca:
  The Royal Society of Chemistry
• Relacja:
  Physical Chemistry Chemical Physics;2014
• Temat i słowa kluczowe:
  tetramethyl compounds;
  carbon family;
  tin and lead organoderivatives;
  gas-phase NMR spectra;
  molecular properties;
  carbon-proton coupling constants;
  pseudopotentials;
  local dense basis sets;
  Bent’s rule;
  Mulliken electronegativity;
  tetrahedral distortion
• Identyfikator:
  R. B. Nazarski, W. Makulski, 1JCH couplings in Group14/IVA tetramethyls from the gas-phase NMR and DFT structural study: a search for the best computational protocol in Physical Chemistry Chemical Physics;2014, DOI: 10.1039/C4CP01596G;
  1463-9076;
  DOI: 10.1039/C4CP01596G ;
  ESSN: 1463-9084;
  http://hdl.handle.net/11089/4889
• Dostawca danych:
  Repozytorium Uniwersytetu Łódzkiego
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