Revealing CSA Tensors and Hydrogen Bonding in Methoxycarbonyl Urea: A combined 13C, 15N and 13C14N2 Dipolar Chemical Shift NMR and DFT Study

Verfasser / Beitragende:
[Sven Macholl, Frank Börner, Gerd Buntkowsky]
Ort, Verlag, Jahr:
2003
Enthalten in:
Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics, 217/12/2003(2003-12-01), 1473-1506
Format:
Artikel (online)
ID: 378862871
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024 7 0 |a 10.1524/zpch.217.12.1473.20470  |2 doi 
035 |a (NATIONALLICENCE)gruyter-10.1524/zpch.217.12.1473.20470 
245 0 0 |a Revealing CSA Tensors and Hydrogen Bonding in Methoxycarbonyl Urea: A combined 13C, 15N and 13C14N2 Dipolar Chemical Shift NMR and DFT Study  |h [Elektronische Daten]  |c [Sven Macholl, Frank Börner, Gerd Buntkowsky] 
520 3 |a 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. 
540 |a © 2003 Oldenbourg Wissenschaftsverlag GmbH 
690 7 |a Thermodynamics & statistical physics  |2 nationallicence 
690 7 |a Laboratory techniques, experiments  |2 nationallicence 
690 7 |a Physical chemistry  |2 nationallicence 
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700 1 |a Börner  |D Frank  |4 aut 
700 1 |a Buntkowsky  |D Gerd  |4 aut 
773 0 |t Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics  |d Oldenbourg Wissenschaftsverlag GmbH  |g 217/12/2003(2003-12-01), 1473-1506  |x 0044-3336  |q 217:12/2003<1473  |1 2003  |2 217  |o zpch 
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950 |B NATIONALLICENCE  |P 700  |E 1-  |a Börner  |D Frank  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Buntkowsky  |D Gerd  |4 aut 
950 |B NATIONALLICENCE  |P 773  |E 0-  |t Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics  |d Oldenbourg Wissenschaftsverlag GmbH  |g 217/12/2003(2003-12-01), 1473-1506  |x 0044-3336  |q 217:12/2003<1473  |1 2003  |2 217  |o zpch 
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