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Electron Density Investigation of a Push–Pull Ethylene (C 14 H 24 N 2 O 2 ⋅H 2 O) by X‐ray Diffraction at T = 21 K
Author(s) -
Forni Alessandra,
Destro Riccardo
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305043
Subject(s) - molecule , crystallography , dipole , charge density , hydrogen bond , ab initio , ab initio quantum chemistry methods , density functional theory , materials science , chemistry , computational chemistry , physics , organic chemistry , quantum mechanics
The electron charge distribution in a strongly twisted push–pull ethylene [PPE, 3‐(1,3‐diisopropyl‐2‐imidazolidinylidene)‐2,4‐pentanedione] has been determined by low temperature ( T = 21 K) single‐crystal X‐ray diffraction analysis. The derived electronic properties are consistent with a zwitterionic molecule, as indicated by a charge transfer of 0.82(16) e from the push to the pull moieties and a charge polarization of 0.29(7) e on the olefinic bond. A dipole moment of 12(3) D has been determined, which compares well with ab initio theoretical results in terms of both modulus and orientation. The second moments, which have also been obtained with good precision, characterize PPE as a highly quadrupolar molecule. The special electronic features of the molecule confer particular topological properties to the electron density distribution, as evidenced by comparison with “standard” organic molecules. The crystallographic asymmetric unit of the present system includes one water molecule, which is hydrogen bonded to PPE. Its topological properties have also been investigated, together with an analysis of the hydrogen bonds involved.