caa a22 4500 378862871 CHVBK 20180305123350.0 cr unu---uuuuu 161128e20031201xx s 000 0 eng 10.1524/zpch.217.12.1473.20470 doi (NATIONALLICENCE)gruyter-10.1524/zpch.217.12.1473.20470 Revealing CSA Tensors and Hydrogen Bonding in Methoxycarbonyl Urea: A combined 13C, 15N and 13C14N2 Dipolar Chemical Shift NMR and DFT Study [Elektronische Daten] [Sven Macholl, Frank Börner, Gerd Buntkowsky] Methoxycarbonyl urea (MCU), a potential long-term nitrogen fertilizer, is studied by 13C and 15N dipolar chemical shift NMR spectroscopy and ab initio calculations. Employing a combination of dipolar chemical shift NMR, selective isotope labeling and ab initio gas phase calculations, possible molecular structures and chemical shielding tensors of all 15N nuclei and of two out of the three 13C nuclei were revealed. Four possible stable configurations of the molecule with different energies were found in the calculations. The CSA tensors were calculated for these configurations. While the calculated 13C(urea) CSA tensor orientation of the configuration with the lowest energy is in good agreement with the experimental tensor orientation, there are pronounced differences between calculated and experimental tensor eigenvalues. These differences are a clear indication of the presence of intermolecular hydrogen bonds in the experimental sample, which are neglected in the gas phase calculations. Four different possible orientations of the experimental 13C(urea) CSA tensor exist, due to symmetry. This ambiguity is solved by comparison with results from GIAO calculations of the 13C CSA tensor, employing the minimum energy configuration (EEZ). It is found that the orientation, where δ11 points approximately in direction of N(imide), δ22 approximately in direction of the C=O bond, and δ33 is oriented perpendicular to the molecular frame, is adopted in the molecule. © 2003 Oldenbourg Wissenschaftsverlag GmbH Thermodynamics & statistical physics nationallicence Laboratory techniques, experiments nationallicence Physical chemistry nationallicence Macholl Sven aut Börner Frank aut Buntkowsky Gerd aut Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics Oldenbourg Wissenschaftsverlag GmbH 217/12/2003(2003-12-01), 1473-1506 0044-3336 217:12/2003<1473 2003 217 zpch https://doi.org/10.1524/zpch.217.12.1473.20470 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/zpch.217.12.1473.20470 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Macholl Sven aut NATIONALLICENCE 700 1- Börner Frank aut NATIONALLICENCE 700 1- Buntkowsky Gerd aut NATIONALLICENCE 773 0- Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics Oldenbourg Wissenschaftsverlag GmbH 217/12/2003(2003-12-01), 1473-1506 0044-3336 217:12/2003<1473 2003 217 zpch CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter